ポスター発表

In animal psychology, video image have often been used in experiments to show objects, conspecifics and heterospecifics to examine response of animals. In such experiments, video images are represented as “real world” for animals, although some factors such as color and depth could be different from actual scenes. Examining similarity and intensity of animal responses evoked by real or video stimuli would give suggestions for further studies. Here we investigated the responses of twenty-eight domestic cats (Felis catus), by showing a sequence of mouse toy rapidly moving from left to right, and left to right. The sequences were shown by video image and in real for twice each. Results showed cats searched the mouse more frequently to directions it disappeared from the scene in Real condition than in Video condition(x2(2) = 12.7, p <.01, Residual analysis: p <.05 in all comparison between conditions). Moreover, cats which were in Video condition showed “no search” more often, which may suggest video image less motivated cats than in real situation. However, other factors, such as background noise, could explain this difference between the two conditions. Further experiment with more controlled environment will be introduced.

Social hierarchy within a group is necessary for survival in many animals. It helps to avoid unnecessary conflicts and establish good relationships with others. Recently oxytocin has received increasing attention for its function in social cognition. However, the relationship between oxytocin and social hierarchy has remained unknown. Here we examined the effects of pharmacological manipulations of oxytocin on social hierarchy using a tube task. In the tube test, mice in the same cage were ranked in a round robin competition. The one that pushed out its opponent was determined as the dominant individual, and the one that got pushed out was determined as the subordinate individual. After letting mice get used to the tube, we tested which mouse is dominant in order. First, we investigated the social hierarchy in a non-oxytocin operational condition. Second, we examined the change of the social hierarchy and social behaviors of the most dominant mouse in the tube test after systemic injection of oxytocin agonist and antagonist. This behavioral and neuroendocrinological approach is an important step to understand the mechanism of the social hierarchy.

Learning is a process where organisms adjust their behavior based on their own experiences. Accumulating evidence suggests that dopamine plays critical roles in the learning process ranging from computing reward prediction error, representing reward value and salience, and modulating motor outputs (Berke, 2018). Learning processes consist of acquisition of new behavior, maintenance of the learned behavior, and adjusting it when the environments change. Each subtype of dopamine receptors play differential roles in various processes of learning. Here we examined the effects of dopamine receptor manipulations on maintenance of learned behavior with a trace conditioning task in head-fixed mice. We presented a 6000 Hz tone for 1-second that is followed by 1-second blank duration, and 10% sucrose solution was delivered while the mice were head-fixed. After the training, mice acquired licking responses to the tone. We conducted pharmacological manipulations of dopamine with each subtype of agonists and antagonists, and investigated how these manipulations affect maintenance of the learned licking responses. We also analyzed the microstructure of licking responses to assess the effect of drugs on the motor control. This research will serve a fundamental challenge to bridge the gap between the behavioral processes of learning and its neural underpinnings.

A variety of behaviors in the rodent pups toward mother have been described by many researchers, however, little is known about mother preference behavior of mouse pups. In this study, we found that C57BL/6 mouse pups at post-neonatal day (PND) 16 showed large variation in mother preference test. Then, pups were classified into three groups based on contact ratio for mother or stranger mother: mother preference (MP) group, non-preference (NP) group, and stranger preference (SP) group.

To reveal the mechanism underlying the individual difference in mother preference, we investigated which brain region has associated these differences. The brain sections from pups in these groups with or without exposure to mother were examined with immunohistochemistry for c-Fos and calculated the densities of c-Fos-immunopositive cells in several brain regions. We found that there is no difference among each group without exposed to mother, whereas NP and SP groups with exposing to mother showed the increase of number of c-Fos-immunopositive cells in anterior cingulate cortex (ACC) and bed nucleus of the stria terminalis (BNST) compared with MP group with exposing to mother. These results suggest that activation of ACC and BNST negatively correlate to pup’s preference for mother in mouse.

Although there are consistent observations in rodents that post-weaning social isolation escalates aggressive behavior, this pro-aggressive effect of social isolation is often limited to fear–induced aggression in the mouse. In this study, we examined the effect of social instigation, a model that induces aggressive arousal and causes escalation of aggressive behavior, in the socially isolated mouse. ICR/Jcl male mice were divided into four groups: experimental groups socially isolated from 3 weeks old (SI-3W), 6 weeks old (SI-6W), and group-housed controls for each condition. At 10 weeks old, their territorial aggression towards a male intruder mouse was examined in the resident–intruder test for 5 min over 3 consecutive days. On the fourth day, the social instigation test was performed. In this procedure, a perforated cylinder containing a male instigator mouse was placed in the resident’s homecage for 5 min followed by the 5-min resident–intruder test. As a result, only the SI-6W group showed a significant increase of aggressive behaviors compared to control in the resident-intruder test, but this was due to low aggressive behavior in the control. On the other hand, we found that social instigation significantly escalated aggressive behavior in both SI-3W and SI-6W groups compared to controls. We also investigated c-fos expression in the lateral habenula (LHb), the brain area which is related to aversive emotion, but there was no statistical significance in the activation of LHb neurons by social instigation between control and isolation groups. These results suggest that socially isolated mice had an enhanced aggressive arousal induced by social instigation and showed heightened aggressive behaviors.

Sensitivity to conspecific’s gaze direction is useful, not only for social interactions but also for foraging and danger avoidance. Therefore, sensitivity to gaze may be a common cognitive function in many species, including those that do not show complex sociality. This study investigated whether attention of pigeons could be captured by the direction of conspecifics’ head (presumably equivalent to “gaze” direction for pigeons) presented on the screen. First, we trained pigeons to peck on the target to gain food. Next, we added cues, which were pictures of pigeon’s head, shortly before presentation of the target. Pigeon’s head was displayed either facing the target (congruent) or away from it (incongruent) and the frequency of each conditions was 50%. Comparison of the reaction times of the two conditions revealed no significant difference, suggesting that pigeons have no predisposition in where to direct their attention. In the second phase of the experiment, we tested whether the subjects would learn to use the same stimuli as cues when they predict the target location with high probability. The pigeons’ reaction times decreased in the cue-predicted condition, suggesting that pigeons can learn to use the gaze direction of conspecifics when anticipating the location of the target stimulus.

Recent studies using operant paradigms has shown the vocal control ability of birds to emit different vocalizations depending on different visual or sound cues. However, it remains unclear for what environmental information individual birds differentially encode in vocalizations under natural settings. Crows, a bird species living in urban areas closely to humans, are found to be able to visually discriminate human individuals and also known to have the flexible audio-vocal ability. These previous findings raise the possibility that vocal signals of crows encode different human individuals. However, no previous study has tested this possibility. Here we investigated the acoustical difference of a specific call type (sequential ka call) emitted by group-housed large-billed crows in response to different human individuals in an experimental setting. The sequential ka call consists of 3 – 15 elements with 0.2 – 0.5 sec intervals in a sequence. In the experiment, we recorded calls in response to a familiar / unfamiliar person approaching to the crows’ home aviary. Then, we analyzed the acoustical differences of calls recorded from the same crow between familiar and unfamiliar human stimuli. Crows produced calls more often to unfamiliar stimuli than to familiar ones. Furthermore, the calls to unfamiliar stimuli consist of longer elements and shorter inter-element intervals. These results suggest that crows encode different human individuals in their vocalizations.

Time-restricted feeding (TRF: access to food during only the active phase) can improve metabolic health in mice and rats. This study investigated the effects of TRF of sugar on free-feeding rats’ body weight gain. Rats were housed individually in the modified operant chambers for 8 weeks. Standard food chow and water was always available to all rats. Operant-feeding sessions (60min long) were given four times each day. During the operant-feeding sessions, every lever-press response was reinforced by a sugar pellet (continuous reinforcement schedule). In the TRF group, all four operant-feeding sessions were provided during the dark phase of the day. In the control group, two operant-feeding sessions were provided during the dark phase and the remaining two operant-feeding sessions were provided during the light phase. Sugar consumption in the operant-feeding sessions was larger in the TRF than the control groups. Chow consumption was not different between the groups. Body-weight gain were similar in the TRF and the control groups. These results suggest that TRF affects energy metabolism.

Vocalization subserves social interactions, while social cues elicit vocal interactions. Songbirds vocalize specific sounds to evoke other conspecifics' social behavior, e.g., gathering each other when they are alone. This suggests that birds can learn to associate vocalizations with social feedback. The present study assessed whether a social songbird, the zebra finch, can learn to modify vocalization according to social feedback. We utilized the vocal operant conditioning paradigm with the social reward, where the bird can see its cagemate when the bird vocalizes appropriately after LED or tone cues. Preliminary data showed increases in vocalization rates immediately after LED/tone presentations associated with the social reward. The possibility of modifying acoustical features of vocalizations will also be discussed.

Age differences in the development of the symptoms of PTSD were suggested in previous human questionnaire survey studies. To examine whether such age-dependent symptoms are also observed in an animal PTSD model, anxiety-like behaviors measured by the open field test, light/dark transition test, and elevated plus maze test were compared between preadolescent- and adolescent rats exposed to a single prolonged stress (SPS) procedure (sequential exposure to restraint, forced swimming, and agents inducing anesthesia). For anesthesia in the SPS procedure, we used a mixture of three anesthetic agents (medetomidine, midazolam, and butorphanol) for safety purposes instead of ether. Although the effects of SPS on the anxiety-like behaviors were not detected regardless of age, anxiety-like behaviors measured by the light/dark transition test and elevated plus maze test demonstrated an opposite age-dependency irrespective of SPS; in the light/dark transition test, adolescent rats exhibited lower anxiety, whereas in the elevated plus maze test, preadolescent rats exhibited lower anxiety. This suggested that the usage of a mixture of three anesthetic agents as anesthesia in the SPS procedure was insufficient for PTSD induction, and these agents may have had therapeutic effects on PTSD. As the age-dependency of anxiety-like behaviors differed among behavioral tests, usage of multiple behavioral tests to examine the age-dependency of PTSD is desirable.

During behavioral coordination, we represent the action of the partner. We examined whether rats show such co-representation of the action toward the common goal by joint Simon task. Rats were reported to show Simon effect, which is the compatibility effect occurs when the stimulus was presented at the opposite side to the required response. Studies on human showed this effect disappears when performing only either the half side of the task (go/nogo task). However, the compatibility effect reappears when this half task was performed with another person side by side.

Here, pair housed rats learned to respond by right lever to 12kHz tone, and by left lever to 3kHz tone. In the test, an auditory stimulus was presented from either the left or right speaker. They were tested on a full Simon task and its half task in both single and joint conditions. Rats showed lower correct rates when the stimulus and response were incongruent in full Simon and the paired half task, whereas such effect was not observed in the single half or paired control task. Thus, rats were not able to ignore the stimulus irrelevant to their own action in joint task. This finding indicates the possibility that basic ability for behavioral coordination is shared with nonhuman mammals.

Lactobacillus reuteri is a species of lactobacillus and oral administration of L.reuteri has been found to stimulate the oxytocin secretion in mice. Since oxytocin has a stress-relieving effect and is expected to reduce anxiety behaviors, the present study aimed to examine whether administration of L.reuteri reduced stress and improved anxiety behaviors in dogs. Six dogs exhibiting behavioral problems in anxiety were orally administered with L.reuteri 6475 (0.0025g/kg) twice a day for 4 weeks. We collected dog’s urine once before administration and once every two weeks during administration and urinary oxytocin and cortisol levels were measured. The assessments of dog’s behavior (C-barq) were conducted by their owners before and after administration. The results showed that oxytocin levels were elevated in 4 out of 6 dogs and cortisol levels were reduced in 5 dogs after administration of L.reuteri. In addition, the negative correlation between oxytocin levels and the score of fear of other dogs and the positive correlation between cortisol levels and aggression toward strangers were found, indicating that each hormone is related to dog’s behavior and temperament. These results suggested that the action of L.reuteri on the oxytocin nervous system to promote oxytocin secretion and reduce cortisol secretion, may have reduced the fear and aggressive behavior in the dogs.

Cats are naturally solitary animals, but nowadays they have come to live in groups. We found the negative correlations of cortisol and food share, and oxytocin and affinity contact in group-living cats, suggesting that these hormones are involved in social behavior of cats. Thermoregulation by social contact is one of the basic functions of group formation, and both cortisol and oxytocin have a thermogenic function. We examined the changes of endocrine and social behavior caused by lower environmental temperature. We analyzed cats’ group behavior, oxytocin and cortisol from urine collected in the morning, and body weight and temperature in two temperature conditions, 20 and 26°C. The results showed no difference in endocrine between temperatures, but food share was observed more at 20°C and rubbing body was more at 26°C. There was a positive correlation between oxytocin and sniff, and body temperature and follow, entering bed and food share at 20°C. At 26°C, there was a positive correlation between cortisol and play and a negative correlation between body weight and both grooming and entering bed. In total, it was shown that the factors related to the social behavior expression differed by the degree of thermoregulatory demand depending on environmental temperature.

Both physical and cognitive changes were led by aging. It is still unknown how aging -induced brain changes affected locomotive activity, mood, and cognitive performance. In this study, we investigated the differences of behavior and brain between old and young by using multimodal analysis. Male C57BL/6J mice were used (2-month-old, n = 10; 27-month-old, n = 9). Firstly, general health check and behavioral test battery were conducted. Secondly structural T2W-MRI were acquired under isoflurane anesthesia in 7T-MRI (PharmaScan, Bruker Biospin). In the behavioral result, old mice showed lower muscle strength regardless of their body weight. Higher anxiety-like behaviors were shown in old mice by the open-field test and light-dark transition test. In the result of MRI, the regional white matter volumes were increased in old mice’s brain. On the other hand, the ratio of gray matter volumes of old mice was lower than young mice. In the regression analysis of MRI and behavior, larger volume of auditory cortex was positively correlated with locomotive activity. As a conclusion, the inflammation of white matter could affect the mood and cognitive changes caused by aging. We further continue to analyze the postmortem brains especially in fiber tract.

It has been suggested that chimpanzees and newborn chicks have tendencies to map smaller numbers on the left and larger ones on the right in a mental number line. The present study examined whether rats have any directional tendencies of mapping numerical values mentally. Rats were trained to respond to a third cup in a line of nine cups vertically arranged from a start box in an open field. In a test conducted after the acquisition training, a row of the nine cups horizontally arranged in front of the start box was presented and responses to both the third cups from the left and the right were rewarded equally. Rats’ responses were significantly biased to the third cup from the right end. The results suggest that rats counted the cups from the right end of the row. This result is incompatible with findings in other nonhuman animals. We will report additional results with control of a simple preference for a specific position in the open field.

Modulating social behaviour is essential to maintain affiliative relationships and to avoid conflicts, for animals having prolonged stable relationships, like social monogamous pairs observed in human societies and nonhuman primate species. In social conflicting situation, faster settlement is desirable to reduce both mental and physical health risks of spouses. We examined how pairs of marmosets modulated their behaviour in conflicting situations where they could choose to share rewards, compete for them, or obtain them by domination. Three pairs engaged in the trained tasks for up to 10 sessions. They were free to choose which one would respond to the monitor and which would consume the reward. Three pairs developed differential patterns over sessions: One pair showed monopoly relationships in both responding and reward consumption, the other pairs competed for responses and rewards throughout almost all testing, and showed servitude relationship (where one partner responded and the other consumed the rewards) by the female. The index, “rewards per unit work” successfully differentiated these patterns. The study showed continuous social modulation and resulting dynamic change in the interactions of the pairs, providing evidence of their coping abilities even in high-conflict situations.

Animals selectively direct their gaze attention toward specific targets in their environments. Also, they detect others’ gaze direction to have adaptive behavior. Because birds’ large eyes are less mobile in their sockets, they change the field of view of their eyes by moving their head more extremely (Land, 1999). Thus, we suppose that face direction will be crucial when birds are detecting others’ gaze direction. In this research, we used Bengalese finches (Lonchura striata var. domestica) to examine whether songbirds can discriminate conspecific frontal and lateral face and whether a clear discriminant boundary exists. In our experiment, subjects were trained on a Go/Nogo task to discriminate stimuli composed of conspecific frontal and lateral pictures. In the training phase, we prepared four sets of stimuli captured from different individuals. We started the training with one set of stimuli. When subjects achieved the criteria of 90 percent accuracy, we added one more set and repeated this procedure until four sets were done. After the training, the subjects will be tested with different face angles between the front and side. Currently, four out of seven females have finished discrimination training, which suggests that songbirds can discriminate face angles regardless of individuals. Further details of the test phase will be reported in the poster. (Work supported by JSPS grant #4903, 17H06380)

The genus Macaca consists of many species, and it is known for the wide range geographical distribution, its diverse habitat, and ecology. Because of these characteristics, many comparative studies have been conducted on Macaca species. Regarding their social life, previous studies have focused on social organization, mating systems, and social structures. Authors have categorized Macaca species into four grades based on their social style. According to this 4-grade scale, grade 1 includes the most despotic species, and grade 4 includes the least despotic species.

In this study, a portable touch monitor was introduced to zoo-housed macaques at Japan Monkey Centre and compared their social style under an experimental setting. All procedures were conducted as the open lab style experiment. Participants included six Macaca species, rhesus macaque (Macaca mulatta), Japanese macaque (Macaca fuscata), southern pig-tailed macaque (Macaca nemestrina), Tibetan macaque (Macaca thibetana), bonnet macaque (Macaca radiata), and toque macaque (Macaca sinica). The study started with a habituation phase, then moved to a touch monitor task phase with the tasks gradually becoming more difficult.

The experimenter counted the number of individuals who were able to ‘approach’ the apparatus (touched the apparatus or stayed in front of the monitor) and measured the length of ‘approach’ time. There are differences among species both in the number of individuals and approach time. Moreover, these differences fit the grades presented in previous studies. Thus, this study revealed that macaques’ social style can be duplicated under the experimental setting with zoo-housed captive groups. In addition, zoo visitors can get an opportunity to observe macaques in a new way and to learn about their social styles through the open lab style experiment.

"Animal therapy" is used to support people especially elderly. Breeding relatively large mammals, such as dogs and cats, takes many costs, so it is desirable to use small animals instead. Humans and small animals (i.e., rodents), however, do not share similar social signals, and it makes difficult to empathize mutually. The purpose of this experiment was to establish acoustic parameters that enable small animals and humans to share emotions. Of the ultrasonic sounds of Mongolian gerbil, greeting call (pleasant call), vocalized in friendly contact, and the screaming call (unpleasant call), vocalized in minor conflicts, were converted into the human audible range by the heterodyne method. In order to investigate the effects of frequency and sound pressure, the peak frequency was changed to 5 levels of 2kHz-10kHz, and the sound pressure level of the stimulus was changed to 5 levels of 60dB SPL-70dB SPL. The "negative-positive" and "active-inactive" of the voice were evaluated by human participants using the semantic differential technique. The results showed that simply converting gerbils vocalizations to the human’s audible range makes greeting call and screaming call understood as pleasant and unpleasant respectively. Additionally, humans perceive the arousal of the gerbil's voice based on the sound pressure level.

Paradis and Cabanac (2004) reported reliable food aversion conditioning in reptiles but not in amphibians such as toads and newts. In contrast, Taniuchi (2018, JSAP) showed significant food aversion conditioning to kamaboko CS in Japanese fire-bellied newts. Taniuchi (2019, JSAP) also confirmed reliable food aversion conditioning not only for kamaboko CS but also for pieces of 40 mg beef and mealworms used in the previous study which reported absence of food aversion conditioning in newts. The present study found that the amount of consumed CS food might be a determinant of food aversion conditioning in newts. Experiment 1 was designed to examine latent inhibition, and groups with different treatment of pre-exposure of CS were presented with only three pieces of 40 mg of beef as CS to control the amount of consumed CS across groups. Any sign of food aversion not only in the Control group (CS-saline) but also in the Experimental group (CS-LiCl) was not observed. In Experiment 2, news were presented with ten or three pieces of 40 mg beef and administered with LiCl or saline. Results showed that reliable food aversion conditioning could be found only in the group given ten pieces of CS food. Paradis and Cabanac (2004) reported that their newts did not eat much CS food, but they did not report absolute quantities of consumed CS food. These results suggest that the discrepancy between Paradis and Cabanac (2004) and Taniuchi (2018, 2019) might be explained in terms of differences between the studies in amounts of consumed CS.

The purpose of this study was to examine the association between autonomic responses and body movement synchronization and affiliative relationship between owners and dogs by using heart rate variability and composite acceleration. A previous study showed that emotional contagion from owners to dogs is facilitated by duration of ownership. We hypothesized that a dog's affiliation or duration of ownership are positively correlated with autonomic responses and body movement synchronization between owners and dogs. We attached electrocardiographs and accelerometers to owners and dogs and performed four conditions: resting, separation from owner, motion and search condition. Time domain analysis was used for heart rate variability analysis. We found that the longer duration of ownership, the higher the owner-dog acceleration synchronization in the search condition. Furthermore, the higher the dog’s anxiety from separation, the higher the owner-dog SDNN synchronization in the motion condition, indicating that separation anxiety may be related to attachment. However, there was a negative correlation between duration of ownership and owner-dog rMSSD synchronization in the separation condition. Collectively, there was an association between autonomic responses and body movement synchronization and affiliative relationship, in some conditions and indices.

The present study examined inference in a social situation in rats. First, rats were trained on three daily trials to learn type of food sites. On the first trial, rats were allowed to eat at four food sites in an experimental field. On the second and third trials, two food sites were replenished with foods (replenished sites) but the other two sites were not (depleted sites). All rats learned the type of the food sites and came to visit replenished sites earlier and depleted sites later on the second and third trials. In the test conducted after the training, another demonstrator visited one of the two sites of either site type first, and then a subject rat was given choice between the two sites of same site type; the site of the demonstrator visited and the unvisited one. In Experiment 1 in which other rats served as the demonstrator, rats did not show any sign of social inference; they had a tendency to follow the demonstrator regardless of the type of the food sites. However, in Experiment 2 in which mice were used as demonstrators, subject rats had a tendency to avoid the depleted site visited by the demonstrator and such a tendency was not observed for the replenished sites. These results suggest rats can make some kind of social inference by combining information about behavior of other animals and type of food sites.

Dogs (Canis familiaris) and Cats (Felis silvestris catus) are unique animals that have merged into human society most profoundly. One of the bases for these coexistence is their non-verbal communication. In humans, an eyeblink, as well as a gaze, is an important social signal in communications. Blinks synchronize between two individuals which relate to effective communication and mutual understanding. Dogs and cats also communicate with humans through their gaze. Unconscious eyeblinks in gaze may be an important signal between dogs/cats and humans as well. In the current study, the temporal relationships of eyeblinks between dogs/cats and humans during mutual gaze were analyzed to investigate whether there is synchronization. The human had five episodes of one-minutes of mutual gaze interactions with the dog/cat. Their blinks were recorded during the tests. To account for the effects of relationships between individuals, the owners and strangers participated. As results, owners blinked immediately after dogs/cats blinked and dogs/cats blinked with about one-second delay from humans. The stranger blinked a little later than the blinks of dogs/cats. We found that the mutual and unintentional synchronization of eyeblinks and the time lag depending on familiarity. Although the important issue of what is the biological function of the eyeblinks synchronize remains, these results demonstrate that the dog and cat acquired communication skills using blinks during their domestication process and integration into human society.

The verbal processing of visual objects is known to have influences on subsequent perceptual/cognitive processing of the labeled items in humans. Nonhuman animals are also able to learn visual symbols to classify objects; however, it remains to be understood whether their symbolic labeling affects their visual representation of the labeled items as in humans. In this study, we investigated the effect of categorical labeling on face identity recognition in six capuchin monkeys using symbolic and identity matching-to-sample tasks. Monkeys were required to categorize a face picture into two age classes and then to identify it in one of two faces that belonged to the same or different age categories. In the control condition, the intermediate labeling task was replaced with a face-irrelevant visual detection task. Results showed that in comparison with the control task, age categorization of the faces impaired face identification performance regardless of the within- or between-category condition. We will discuss the results in terms of putative mechanisms of the labeling effect proposed in human studies.

To investigate the spatial ability of rats, we created a complex maze. The maze was a square shape (130 cm x 130 cm) and the internal structure could be freely reconfigured. Each of the four corners of the maze was connected to a box that would be a start box or a goal box. We required rats to go from the start box to the remaining three-goal boxes. When the rats reached one of the goal boxes, a pellet was granted as a reward. A trial consisted of visits of all the goal boxes in any order. The trials were repeated using the last of the three goals boxes visited by the rats as the start box and the remaining three boxes as the goal boxes in the next trial. The configuration of the maze was changed day by day. Thus, the rats had to learn the configuration every day. The performance of the rats suggests that they learn the configuration of the maze and choose a pathway that avoids dead ends. However, the rats might have difficulty maintaining motivation to task for a long period.

Matching-to-sample (MTS) has been often used in animal studies, such as memory and abstract concept ability. Many animals can acquire the MTS task, but there are three strategies by which MTS may be solved: configural strategy, if-then strategy and abstract concept learning.

In this experiment, we examined how rats solve the MTS task with visual stimuli. Four Long-Evans rats were trained on an identity MTS task with patterned black-and-white visual stimuli in an operant chamber attached with an LCD display. A trial began with the presentation of a sample, and a response to the sample resulted in the appearance of the two comparisons. A response to the identical stimulus with the sample was reinforced. The training was started with one stimulus-set (sample: A, comparisons: A and B), and another stimulus-set (sample: C, comparisons: C and D) was added after rats had accomplished the criteria of 90% correct in two successive sessions. After the training, the transfer tests with novel stimuli and another three tests were conducted. Three rats showed the significant transfer to novel stimuli and one also responded correctly without simultaneous sample presentation. These results suggest rats can acquire the abstract concept with the MTS task. (Supported by JSPS grant #4903, 17H06380).

It is known that rats’ radial maze performance becomes less accurate over successive trials in a daily session. Roberts and Dale (1981) hypothesized this proactive interference effect in the radial maze task in terms of failure of discrimination of spatial memories of current and preceding trials. This view predicts that increasing inter-trial interval (ITI) alleviates the proactive interference effect since increasing ITI makes memories in different trials more discriminable. However, Roberts and Dale (1981) failed to find any alleviation of proactive interference by lengthening ITI from one to four minutes. The present study examined effects of longer ITIs on the proactive interference effect in rats’ radial maze performances. In a trial, rats were allowed to enter four arms of an eight arm radial maze in a designated order and then search four unvisited arms among the eight arms. A delay of 60 s separated the forced- and the free-choice trial. During the test period after acquisition training with one daily trial, rats received two trials in a daily session with 5, 30, 60, or 120 min ITI. Rats showed reliably poorer performance on the second trial than on the first trial and no alleviation of proactive inference under 5, 30, or 60 min was found. In contrast, rats showed almost equal performance in the first and the second trials under 120 min ITI. The results suggest that proactive inference persists over an hour but it disappears if ITI is extended to two hours.

Visual motion perception in mice has been investigated by training them to discriminate random dots moving horizontally from those moving vertically. We similarly trained six mice to discriminate random dots moving leftward from those moving upward in a touch screen chamber. Mice were assigned to one of the two groups: one group was trained with a leftward movement as S+ and with an upward one as S-, whereas the reverse was true for the other group. Mice successfully acquired the discrimination by gradually increasing the speed of S- motion. The discrimination performance deteriorated as the directional difference of movement became smaller. When presenting plaid motion stimuli created by superimposing two drifting gratings, mice discriminated them based on the plaid orientation irrespective of drifting direction. Moreover, mice discriminated static plaid stimuli based on their orientation. These results suggest that mice use the plaid orientation solely even when discriminating plaid motion, possibly because of motion blur due to the poor temporal resolution of mouse vision, and that the resulting discriminative behavior might not necessarily reflect the characteristics of visual motion processing.

Oberliessen et al. (2016) compared rats’ choices between two goals: one “equal” goal, where they could get one food pellet and they faced another conspecific rat also rewarded with one food pellet, and one “inequal” goal, where they could get one food pellet and they faced another rat rewarded with three food pellets. Rats preferred the goal with the equal reward with the conspecific but such a tendency was not observed in a control condition in which a toy rat replaced the conspecific. The results of Oberliessen et al. (2016) suggests inequity aversion in rats. However, the absolute difference in choice rate between the equal (52%) and the inequal (48%) goals was very small, albeit statistically significant. The present study replicated the procedure of Oberliessen et al. (2016) using larger differences in amount of food reward given to the conspecific between the equal (one pellet) and inequal (nine pellets) conditions. Two male subject rats tested in a within-subject design showed clear inequity aversion in the social condition in which other conspecifics were rewarded in front of them but such a tendency disappeared completely when the conspecifics were replaced with ceramic objects. These results support the view that rats have inequality aversion.

In human infants, temperament partly predicts core pre-academic skills, such as basic level categories, in the preschool period. We investigated whether in degus temperament in infancy might predict cognitive abilities in the juvenile period. At three weeks of age, nine degus underwent an open-field test and an object-exploration test to measure their temperament, including activity, boldness, and impulsivity. To measure their fundamental cognitive abilities, we used a spatial working memory task for seven days at 5 and 12 weeks of age, respectively. In the working memory task, we set nine identical baited containers with a swing lid in the open field. We analyzed how many times the degus visited each container before they ate all rewards (the number of errors) and the order in which they visited the containers. Although the order of visits tended to be consistent with increasing age, there was no correlation between temperament in infancy and the number of errors in the working memory tasks. Future work should test degus in a greater age range and also take into account individual differences.

Knowledge about body parts helps animals understand others’ behavior and make their owns. Humans have the knowledge about appearances and locations of our body parts. However, it is not clear whether other animals also have this knowledge. In this study, we tested whether chimpanzees can detect strange body parts using eye-tracking. We tested six individuals with pictures of chimpanzee bodies. We focused on manipulations of arms or legs. For either arms or legs, there were four conditions. The first was normal bodies as a control condition. In the second condition, we misplaced one arm or a leg to a strange position. In the third condition, we replaced an arm with a leg, or vice versa. In the fourth condition, we replaced an arm or a leg with a human arm or leg. The AOIs (areas of interest) were the strange body parts in the manipulated conditions or the corresponding ones in the control condition. We found that there were more trials in which chimpanzees had looked at the AOIs in the second and fourth conditions than control. We also found that all the manipulated conditions had longer fixation durations of AOIs than control. In general, chimpanzees paid more attention to the strange body parts than control. This suggests that chimpanzees have the knowledge of the locations and appearances of body parts, as humans do.

Humans have preferences for certain cross-modality combinations. For example, they associate higher-pitched sounds with higher position, and they associate lower-pitched sound with lower position. It seems that other animals also have such preferences. It is because in nature, the sunlight comes from above the sky and many flying animals are small and sing in a high pitch; therefore, high pitch associates with blight, spatially high, and small. However, few studies have examined correspondence between pitch and position and between pitch and size in non-human animals. In this study, three male Long-Evans rats were required to discriminate two visual stimuluses. One was a small black circle which located higher in the white screen. The another was a large black circle which located lower in the screen. We are examining the discriminations which use white circles in the black screen. After they achieved the learning criteria, they heard irrelevant background sounds that were either high (4000 Hz) or low-pitched (2000 Hz) and discriminated these stimuluses. We expected that if rats had the cross-modal correspondence, they performed better (react faster or correctly) in congruent condition (high-pitched for small/spatially high stimulus and low-pitched for large/ spatially low stimulus). As a result, two of them performed significantly better in congruent condition than incongruent condition.

Metamemory, namely the recognition of one's own memory, is a kind of metacognition. Studies of metamemory in non-human animals have been advanced in primates, birds, and rodents. However, it is difficult to approach the evolution of this ability through animal experiments. In this study, we consist of a computational model of metamemory based on existing hypotheses and use evolutionary simulations to reveal its adaptive function. In our model, we will consider the rat as the smallest system capable of metamemory as a mammal and will correspond to the findings. We define metamemory as the system that monitor the rate of agreement between the correct template for the task stored in long-term memory and the sample in short-term memory and promote us to reconfirm the sample if the rate of agreement is below a certain level. We expect that two abilities, short-term memory for retaining sample and metamemory for reconfirming sample, are in evolutionarily competitive relationship. In other words, when the capacity for memory retaining in short-term memory is high, metamemory is not necessary. In our evolutionary simulation, we take two abilities' costs and benefits as parameters and search the conditions and processes under which metamemory emerges in addition to short-term memory.

Our world is full of uncertainties. Animals including humans need to adjust their behavior flexibly in ever-changing environments. Reversal learning task has been used for capturing the ability of cognitive flexibility in many species. Here we established a new spatio-temporal reversal learning task for head-fixed mice. Using the head-fix experimental design, behavioral measures can be simplified by eliminating complex behavioral sequences observed in freely moving animals. First, we trained head fixed mice on a fixed-time (FT) schedule task. We delivered 10% sucrose solution every 10 seconds with a single licking spout placed within licking distance of the mice. After the mice showed anticipatory licking toward the timing of the sucrose solution delivery, we started to train the mice on the FT schedule task with two licking spouts. In this task, we delivered the sucrose solution through one of the two spouts. Every 10 trials, the rewarding spout was switched. Mice quickly learned to switch the anticipatory licking to the rewarding side of the spouts, suggesting that they learned this head-fixed reversal learning task. This novel head-fixed reversal learning task is a useful approach to study the neurobiological mechanism of cognitive flexibility.

Conspecific faces attract more attention than other body parts in many animals. Behavioural and neurological studies have shown that the eye is the important element for attention to the face. Some species (human, chimpanzees) can utilize the gaze direction to know the interest of another individual, therefore it has been interpreted that animals prefer the eyes among the faces. However, eye preference has been reported in non-gaze-following species (macaque, sheep and birds), and these evolutionary origin and ecological significance are still unclear. Recently, it is revealed that a species of cichlid fish, Neolamprologus pulcher, focus on the face. However, it has not been clarified what kind of facial elements are key for such gaze preference. Therefore, we took pictures of N. pulcher’s face and combined or removed these elements (e.g. eye, contour, and patterns) to create face-like stimuli. Then we presented these stimuli to N. pulcher and observed which body parts they gazed. Comparing the duration and number of gazing for the head (face) area, we assessed the influence of the presence of each element on their preference for faces. Our results show that the presence or absence of eye has a significant effect on gazing behaviour and it might suggests that such eye preference had been acquired in the early stage of the evolution in vertebrates.

Tameness is a major behavioral parameter which largely associate with domestication of animals. It has already been reported that domestication of animals has changed not only tameness but also other morphological characteristics and vocal communication. For example, it is known that domesticated animals generally have shorter muzzle and smaller body size. It has also been reported that many poultry utter complex songs more frequently than wild species. In the previous study, we compared ultrasonic vocalizations (USV) between wild and laboratory mouse strains, and showed that the laboratory strains emit USV more frequently. In the recent study, we have succeeded in selective breeding of wild mouse populations for tameness and established domesticated mouse populations in a relatively small number of generations. Therefore, we investigated whether changes in morphology and USV were observed in these domesticated mouse populations. As a result, it was revealed that selective breeding for tameness did not result in significant changes in morphology and ultrasonic vocalization so far.

The spatial-numerical association of response codes (SNARC) refers to a spatial organization of numerical information. When making numerical judgments, humans typically respond faster to small numbers presented on the left and to large numbers presented on the right. We examined whether mice show the SNARC effect like that of humans. Mice were first trained to discriminate eight dots from four dots in a two alternative forced choice task. We then tested mice in a series of generalization tests and showed that mice used relative numerosity in the discrimination. We further tested the SNARC effect by presenting equal numbers of dots (2, 4, 8, or 16) side by side. Unlike humans, mice showed a tendency to choose right when the number of dots increased but the trend was not consistent at the group level.

The mechanism of autism spectrum disorders (ASD) is still unclear, and the major causative genes have not yet been identified. Under such circumstances, attention is started being paid to the increased risk of developing autism due to drug intake. It has been confirmed in humans that the use of selective serotonin reuptake inhibitors (SSRIs) and Valproates (VPAs) during pregnancy increases the risk of developing autism in their offspring. In addition, it was also found in animal model studies that pups mice born from the mother mice that were exposed to VPA during pregnancy showed significantly more autism-like behavior than wild type pup mice up to the third generation. In the present study, to verify how exposing to SSRIs during pregnancy period of female mice affects offspring, we observed a mouse model delivered from female mice that exposed to Fluoxetine (FLX), which is a kind of SSRIs, during pregnancy. As indicators of autism-like behavior, we analyzed ultrasonic vocalizations (USVs) in different age stages, which have been increasingly used in basic research on autism in recent years. As a result, the developmental change and its trends of vocal activity in pups (measured at postnatal day 5, 7, 9) differed among the groups exposed to FLX and control.

Nakamura et al. (2008) demonstrated a reversed Ebbinghaus-Titchener illusion in pigeons, suggesting that when the target circle is surrounded by larger inducers, pigeons perceived the target to be larger than its actual size. Pigeons have local oriented perception (Cook, 1992) such that the target size may be assimilated to surrounding circles. Shorter target-inducer distances may force pigeons to process the global configuration of the stimuli, enhancing the pigeons to perceive the illusion in a similar way as humans do. We first trained pigeons to report the target size with a constant target-inducer distance and, then, tested them by manipulating the target-inducer distance and the inducer size. The discrimination accuracy deteriorated in the long-distance condition, whereas the effect of the inducer size was inconsistent between the subjects. To investigate the role of inducers in the training phase, we trained new pigeons with the target circle only, without the inducers, and then tested them in the same way as in the previous test. The low discrimination accuracy in the short-distance condition suggests that the inducers hinder pigeons’ performance on the target size discrimination. In contrast, the results in the long-distance condition suggest an assimilation illusion occurred when the inducers were far enough not to interfere with the target size discrimination.

Humans have both emotional connections based on kinship and cognitive connections that are built on reciprocal interests. While dogs lack the tightness of intraspecies or kinship-based groups, they also have the ability to form affiliative relationships with heterogeneous, such as humans. Therefore, this study aimed to investigate whether dogs have the ability to exchange objects with unfamiliar humans based on the dog’s value as a basis for cognitive connections. In Experiment 1, the dogs were presented with five types of toys to rank their preference. Then, the toys of different rankings were exchanged between the dogs and human partners. The results showed that the difference in the rankings of the toys presented were related with the latency to exchange, suggesting that the dogs understand the value of what they and their partners have and exhibit appropriate exchanging behavior. In Experiment 2, we examined whether the human partner's preference in the toy affected the dog's exchanging behavior. The dogs tended to change their exchanging behavior after they were presented with the partner's preference of the toy; however, did not change their behavior to match the degree of the partners' preference.

The present study examined whether rats can utilize different sets of extra-maze cues to discriminate memories between two successive trials in a radial-maze task. A trial consisted of a first four forced arm choices as a learning phase, followed by a free choice test on the unvisited four arms among all of the eight arms. Two different sets of extra-maze-cues consisted of four different objects, each of which was presented on the white walls surrounding the radial maze. Rats’ performances reached better than 75% correct for either of these stimuli-sets. However, removal of the extra-maze cues did not affect rats’ performances; they kept their same 75% correct maze performance as in the normal training trial with the stimulus-sets. The results suggest that rats performed this task using some unidentified cues but not the intended stimuli-sets. In order to investigate whether rats can utilize different extra-maze cues for different trials in order to reduce proactive interference, improvement of experimental procedures to make rats utilize the intended extra-maze cues is needed.

There have been many researches that investigating the ability of pictures’ recognition in the Jungle crows (Corvus macrorynchos), but it is little known what kind of factors in the picture they adopt for the recognition. In this research, we trained crows to select the pictures of specific species of bird, and examined the effects of the pictures’ modification on their selection. Four adult Jungle crows were used. Two of them were trained to select a picture of sparrow from other species of birds in the two choice test, and other two crows were trained to select a picture of pigeon. After they got to select the ‘correct bird’ by the binominal test, they were tasked to select the modified pictures.

Novel photos and variously modified images were tried: normal but unfamiliar pictures, grayscale, line drawing, illustration, color-pattern exchanged pictures, extracted five colors, scrambled pictures, and blurred pictures. Our results show that crows' discrimination is greatly influenced by information about the color of the image. It was also found that crows did not judge the correct answer by color alone, but also by the shape of the image.

Previous studies have shown that living with dogs result in changes of endocrine responses, gut microbiota, and behavioral and emotional synchronization in both humans and dogs. However, it is unclear how these changes occur. The purpose of this study is to examine the changes in endocrine secretion, gut microbiota, and behavioral interaction between humans and dogs in 6-month follow-up study after adoption of shelter dogs, and to clarify the mechanisms of how the human-dog relationship forms. We collected urine and fecal samples from both humans and dogs once a month. Urinary cortisol levels were measured and composition of gut microbiota were analyzed. The mood states in behavior, temperament in dogs, and the activity levels in both humans and dogs were also measured. The results showed that cortisol levels in dogs decreased while human cortisol levels tended to increase. The positive correlation was found between human cortisol levels and positive mood states, suggesting that increase of cortisol level was not due to stress, but rather than effect of increased activity as a metabolic hormone. We also found that some species of gut microbiota related to both the mood state such as vitality and friendship in humans and aggressive behavior in dogs. In our future studies, we will analyze the activity level to examine the effect on the physical and mental changes.

We examined whether cats understand the referential meaning of human utterances. We used family’s faces and names as visual or auditory stimuli using a cross-modal expectancy violation method. Cats were presented with a blank monitor and either family A’s or family B’s name were played back four times. Soon after that, either family A’s or family B’s photo appeared in the monitor; there were four conditions in total. If cats knew the family names referred to “the family”, they would look at the monitor longer in incongruent conditions. Results showed that time spent looking at the monitor was longer in incongruent condition in the cats who live with more than 3 human family members. Cats living with just 2 human family members did not show the tendency probably because the frequency of calling each other’s names was lower. Furthermore, we found more time spent together lead to more time looking in the incongruent condition. These results suggested that cats know family’s names through their daily life and its referential meaning without an extensive training with reward.

In situations where an anticipated reward presentation is delayed, various behaviors that do not directly contribute to appetitive results are observed in an operant conditioning task. We determined how sign-tracking and goal-tracking behaviors would change depending on the length of the reward delay. We measured both lever-pressing and nose-poke responses to acquire a pellet in a Skinner box by using well-trained mice under five delay lengths of 0 (no delay), 10, 20, 30, and 40 seconds from pressing the lever to the presentation of a food pellet. The frequency of lever-pressing and nose-poke responses at the second, third, and fourth 10-second intervals within the five reward delays was estimated by calculating the difference between the number of these responses observed in the trials with the different delay lengths of 10 and 20 seconds, 20 and 30 seconds, and 30 and 40 seconds. The results showed that nose-poke responses appeared most frequently at the fourth 10-second interval, while lever-pressing responses were more frequent at the first and second intervals. Furthermore, the estimated number of lever-pressing responses at the second 10-second interval was negatively correlated with the estimated number of lever-pressing responses at the third. However, the former correlated positively with the estimated number of nose-poke responses at the fourth interval. It suggests that the animals who pressed the lever more frequently at the earlier period showed the same response less frequently later, followed by a higher increase in nose-poke responses. A transition process from sign-tracking to goal-tracking when withholding a reward could be affected by the response frequency of a frustrated animal in the earlier period.

Physical features of detained dogs in local health office in Shunan, Yamaguchi are compared with the registered dogs. The results indicate that these detained dogs are not the lost dogs waiting for the owners to claim, but are dogs reproducing on their own in the area for generations, so-called free-ranging dogs (FRDs).

While 70-80% of dogs in the world are known to be FRDs (Kaminski & Marshall-Pescini, 2014) and various studies have been conducted recently. Japan could provide a new perspectives on how the recent emergence of FRDs and how they manage to survive with the protection of locals.

The relationship between nicotine ingestion and depressive-like behavior in rats remains controversial. Considering the factors of duration and preference of nicotine ingestion, we examined the effects of chronic nicotine ingestion and its withdrawal on rat depressive-like behavior using a two-bottle (nicotine solution and water) procedure to provide the subjects with voluntary nicotine ingestion according to their preference. The subjects were divided into three groups (chronic/abstinence/control) according to nicotine presentation and its duration, and behavioral tests were conducted two weeks after the nicotine presentation periods. As a result, (a) in comparison with the abstinence group, the chronic group had a higher preference for sucrose solution in the sucrose preference test on the day after the forced swim test. (b) When comparing the sucrose preferences between the baseline trial and the post-stress trial, there was an increase in the chronic group, whereas neither the abstinence nor control group exhibited any changes. (c) There was no difference among groups in the immobility time or latency to the expression of the immobile state. (d) No correlation between depressive-like behavior and nicotine preference was found. In conclusion, this study demonstrated that chronic oral ingestion of nicotine reduces anhedonic behavior, but it does not affect learned helplessness behavior.

In humans, attention improves perceptual performance on visual detection and discrimination tasks (reviewed in Carrasco & Barbot, 2019). In addition, attention alters the appearance of the visual stimuli on those tasks. For example, transient attention increases the apparent spatial frequency of Gabor stimuli (Gobell & Carrasco, 2005). However, little has been reported on whether similar phenomenon can be seen in other animal species.

In the present study, we investigated whether attention improves the accuracy of discrimination of Gabor stimuli and increases their apparent spatial frequency.

We presented one of six Gabor stimulus differing in spatial frequency and trained pigeons to report whether the frequency of the stimuli was high or low. After pigeons learned the task, we presented a valid transient precue that appeared at the same location as the following Gabor stimulus. If attention in pigeons would enhance the accuracy of spatial frequency discrimination and affect the appearance of spatial frequency in a similar way to humans, the curve of psychometric function should be steeper and PSE (point of subjective equality) should be lower in valid cue condition than those in no-cue condition. The results will be presented at the meeting.

Interval timing in the seconds to minutes range is essential to survival in many species, yet the underlying mechanisms remain unknown (Buhusi and Meck, 2005). The hippocampus is one of the several brain regions that is thought to be involved in interval timing. Here we examined the effects of optogenetic manipulations of GABAergic neurons in the hippocampus on interval timing using head-fixed mice. Using a head-fixed setup, we trained water-deprived mice on temporal conditioning tasks. In the fixed-time (FT) schedule task, we delivered 10% sucrose solution every 10 seconds with a blunt-tipped needle placed within the licking distance of the mice. Early in the training, mice showed robust consumption licking but no anticipatory licking. After the training, mice showed anticipatory licking. In peak trials, sucrose solution delivery was omitted and 30-40 seconds of probe trials were inserted up to 20% probability to assess the temporal prediction of the mice. After the mice were trained both on the FT schedule and the peak procedure, we either stimulated or inhibited the GABAergic neurons in the hippocampus using optogenetics while the mice underwent the FT schedule task with peak trials. This will be an important step to understand the causal relationship between the hippocampus and interval timing.

The internal physiological state of the body has a strong influence on behavior of animals. Recent studies in mammals have shown that the visceral cortex plays an important role not only in top-down control of autonomic functions but also in decision making and learning. In birds, earlier tract-tracing studies suggested Nidopallium Intermedium medialis (NIM) receiving visceral sensory inputs from the thalamus via pons and medulla. However, no studies have yet examined the visceral function of the NIM. Intraperitoneal (i.p.) injection of LiCl solution, a stimulant of visceral organs causing aversive malaise state, was found to increase neural activities in the visceral cortex of the rodents.ﾊIn the previous study of pigeons, we found that i.p. injection of LiCl decreased feeding behavior and heart rate with increasing c-fos immunoreactivity in the NIM. The present study aimed to investigate the role of the NIM in feeding behavior of pigeons by bilateral chemical lesions of the NIM. We predicted that LiCl-induced malaise would be attenuated by NIM-lesion compared to the sham-lesion of NIM. The result of the lesion study would be reported on the day of this conference.

Studies of empathy reported that rats demonstrate empathy-driven prosocial behavior. However, prosocial behavior in mice is not well known. In this study, we examined prosocial behavior in selectively bred wild-derived heterogeneous stock (WHS) S2 mice that is known to demonstrate active contact behavior toward human hand. An experimental box consisted of ground and pool areas. A hole connecting the two areas were locked by a sliding door, and the door automatically opened when a helper pulled down a latch bar in front of the door. A WHS-S2 mouse assigned as a helper was placed in the ground area, and its same-sex cagemate assigned as a distressed demonstrator was locked in the pool area. The helper was repetitively tested whether it opens the door to release its cagemate from the pool area. Compared with C57BL/6NCrSlc mice used as a control group, the WHS-S2 mice quickly showed the door-opening behavior. This result suggests that WHS-S2 mice have an ability to demonstrate helping behavior toward distressed conspecifics.

In this study, we examined the cognitive function of Alzheimer’s Disease (AD) model rat. In addition, the relationship between cognitive task performance and brain morphology was analyzed. Rats injected amyloid-beta into their brain ventricles were used as AD model rats (n=8). To investigate their cognitive function, we used spontaneous object recognition task, that is a one of the memory tasks that utilize animal’s innate tendency to explore novel object compared to familiar object. The task was constructed sample phase and test phase, and a delay period was inserted between them. In the sample phase, rat introduced to an open field where two identical objects were placed to arbitrary points. The rat explored the field freely, and the duration of exploration to the objects was measured. In the test phase, following delay period, the rat was introduced to the same field again, but one object was replaced with a novel object. Whereas control rats (n=7) showed longer exploration behavior to the novel object than familiar one, AD model rats did not distinguish between the novel and familiar objects. Structural brain images obtained by MRI were analyzed by voxel-based morphometry. Correlation analysis revealed positive correlation between task performance and gray matter volume (r=.411, p=.128), and negative correlation between task performance and ventricles volume (r=-.448, p=.094). These results suggest that AD model rats in this study showed cognitive disfunction. Further analysis is necessary to elucidate the relationship between cognitive disfunction and brain morphological change induced by amyloid-beta injection.

We trained rats to respond to a “third” stimulus among six same objects arranged in a row. The objects were put on one of ten goal wells filled with sand in a rectangular open field. A food reward was placed at the bottom of a correct well (under the third object). Since the assignment of objects to the wells was changed trial to trial, rats could identify the correct stimulus based on neither location of specific goal box nor distance from start point. Additionally, inaccessible food rewards put in wire mesh tea strainers were set in the incorrect wells to control possible odor cues. Rats learned the numerical discrimination task reliably. In the next phase, partitions with openings were inserted between the goal wells and thus rats could encounter the object stimuli only sequentially. Although rats’ performances deteriorated initially, they recovered rapidly and reached reliable levels. When different types of objects were introduced to the task, rats kept their good performance. These results suggest that rats can mentally enumerate the number of object stimuli in an abstract manner.

In primate, recognition of facial expressions at a glance is assumed to rely on neural mechanisms in the temporal lobe where characteristics of faces are processed. The temporal cortex is also known to be involved in visual processing about material properties of objects. To investigate how the temporal cortex represents differences in facial surface properties, we recorded neuronal activity in two monkeys while presenting monkey/human faces (three individuals and three expressions each) with different textures (high-gloss, low-gloss, and style-transferred images) in a fixation task. Almost half of the face-responsive neurons showed significant changes in responses to the different textures. The amount of mutual information in the neural responses suggested that the strength of the expression representation was reduced in the style-transferred images, compared to the original. To find behavioral correlates of these neuronal findings, we further investigated effects of the different facial textures on learning processes in a discrimination task. The monkeys were trained to choose one of two facial images by directing a saccade. Their performance was partially impaired in discriminating the expressions of the style-transferred images. Our results indicated that the temporal cortex might play a key role in processing the physical surface properties of faces associated with age, health and emotional states.

Animals tend to reduce consumption of a new tastant due to prevent the ingestion of large amounts of potentially toxic stimuli (taste neophobia). Here, we analyzed ingestive behaviors of rats at the exposure to a novel taste solution. For the neophobia test, water-deprived rats were presented with one bottle filled with novel taste solution (25 mM saccharin) for 20 minutes in the experimental chamber for analysis of the behavior to approach and lick a spout of bottle. In this test, numbers of licking were significantly decreased comparing with those in the water baseline trial, while frequency and duration of approaches to the vicinity of the spout were not, indicating that the rats showed a reluctance to consume the novel tastant without avoiding it. These behavioral analysis will help to promote future investigation into neural mechanisms underlying expression of taste neophobia.

The present study examined the preference in rats of different age groups for solutions that have been used in typical anticipatory contrast experiments. Experiment 1 examined the preference for 0.15% saccharin and 32% sucrose solutions. Old group (24 mo, n=11), middle-aged group (13 mo, n=12), and young group (2 mo, n=12) were presented with water and either of the sweet solutions (two bottle test) or with water and both of the two solutions (three bottle test) for 48 hours. In Experiment 2, tests identical to those in Experiment 1 were repeated by shortening the duration of the tests to 5 minutes, as in the anticipatory contrast experiments. Experiment 3 examined the preference for 4% sucrose and 32% sucrose solutions for 5 minutes. In Experiment 1, intake of the sucrose was higher than the saccharin only in the three-bottle tests of old and middle-aged groups, regardless of restriction of daily food. However, in the food restricted condition in which rats allowed one hour access to food, rats consumed 32% sucrose solution more than 0.15% saccharin (Experiment 2) or 4% sucrose solutions (Experiment 3) regardless of age conditions. These results show that rats prefer 32% sucrose solution than 0.15% saccharin or 4% sucrose solutions regardless of age in the typical experimental condition of anticipatory contrast. The present results ensure the validity of comparing anticipatory contrast in rats of different ages through the typical anticipatory contrast procedure.

Recently drones are used to analyze the spatial positioning of individuals in horses and GPS location to analyze the locomotion of the dogs, and these elucidated the dynamic movement of group behavior. In this study, we used drones to establish a method for analyzing the dynamic locomotion of dogs in a group and to examine how they show dynamic locomotion in response to external stimuli. A drone was used to record the locomotion of the dogs. Tracking software was used to analyze the trajectory against aggressive dog barks playbacked through speakers. We also examined the influence of the owner's presence on the dogs’ movement .As a result, we were able to analyze the dynamic of locomotion of dogs, such as the distance and the interaction of movement between individuals using the video taken from drones. In the group with their owners, the dogs moved away from the human more immediately after the barking sound was playbacked than with an unfamiliar person. After one of the dogs in the group stopped, the dogs moved back to its owner. These results show that the trajectory of the dog groups can be analyzed in detail and that the movement of the dog groups changes depending on the presence of the owner.

The current experiment used a concurrent-chains procedure to examine ‘the sunk time effect’, persistence in a suboptimal option due to prior investments of time, in pigeons. After an initial investment of Z-s fixed interval (FI) on center red key, two side keys were concurrently available in the terminal link. Responses on the left red key made food available after a short fixed interval of time (FI 8-s) on random half of the trials, or no food (Extinction) after a longer time on remaining trials. Two pecks on the right green key allowed pigeons to abort the trial and start a new one. In this situation, proportions of “persistence” trials in extinction were taken as a measure of sunk time effect. All subjects experienced three phases where the ratio of the short-FI/Extinction duration was manipulated (1:4, 1:8, 1:16, respectively) while maintaining the short-FI at a fixed duration. When the ratio was relatively low, all pigeons showed high percentage of persistence and displayed the characteristic peak timing function which peaked at approximately same time in both short-FI and Extinction trials. Nevertheless, when the ratio of duration grew larger, all subjects started responding optimally. Manipulating Z value, an initial link investment, however, did not affect the choice pattern between groups.

We can gain behavioral benefit such as increased accuracy and rapid response by integrating auditory and visual information. Three principles, temporal rule, spatial rule and principle of inverse effectiveness, influence the audio-visual integration. As far as we know, however, few researches examine three principals at the same species. We focused on Mongolian gerbil (Meriones unguiculatus) and investigated whether gerbil’s behavior follows these principles. We first trained head-fixed gerbils to lick when detected a brief flash or sound, and then measured the detection threshold. Auditory and visual stimuli of various intensity were presented simultaneously to investigate inverse effectiveness in gerbil. As a result, gerbil revealed higher detection rate to audiovisual stimuli compared to unisensory stimuli when their intensities were around the perceptual threshold. Next, we examine temporal rule. Different time of onset between auditory and visual stimuli were presented. Gerbil more rapidly responded to temporally congruent audiovisual stimuli than incongruent stimuli. These results suggest that the behavior follows the principle of inverse effectiveness and temporal rule. In current study, we investigate whether gerbil follows “spatial rule”. Our head-fixed setup was useful to study three principles, and we plan to examine how these principles interact with each other in the neural level in the future study.

Many cat owners report their cats watch television programs, especially those that involve motion. The objective of the current study was to investigate what kind of object motion presented on the screen domestic cats pay attention and emit spontaneous responses to. Random movements, which more closely resemble animal movements, may attract more attention compared to objects moving at a constant speed. We tested pet cats in their homes using a tablet PC and observed their spontaneous reactions to moving images on the screen. Cats were free to move around the room during the experiment and the tablet PC was placed on the floor where they could see. On the screen, a green circle moved with 3 different types of motions in a rectangular path against a black background: constant speed, fast-to-slow alternate, and fast-to-slow random. In addition to recording touch responses directed to the screen, we used video cameras to record time to approach the screen and duration and timing of looks to the screen. We will discuss the effect of motion type on the cats’ behavioural measures above, as well as how their behavior relates to the scores on the personality questionnaire answered by the owners.

In recent primates’ studies, curiosity is defined as a motivational state that prompt organisms to explore around themselves and to gather information to reduce uncertainty. However, there are few researches about curiosity in rodents. We examined whether rats show behavior by which uncertainty of information is reduced. First, the rats were trained to choose one of three spouts to obtain a drop of water as a reward. The correct spout was cued by visual stimuli presented above the spouts. The criterion for the training was more than 80 % of the correct responses in a session for four consecutive days. Next, all of the visual stimuli above the three spouts were presented. The rats could turn off incorrect visual cues by briefly staying at the start area, that is, the rats could obtain information excluded uncertainty about reward acquisition. As a result, the rats stayed the start area in a half of trials in a session. However, the rats obtained the rewards only in 60 % of those trials. This result suggests that the rats did not fully use the information for reward acquisition yielded by the staying behavior. It is necessary to train the rats to fully utilize the information.

Dyadic dominance relationship in mammals and birds is formed based on memory of win / loss experiences at the first encounter between individuals. The defeated individuals, defined as subordinates, become suppress aggressive behavior and to express submissive behavior to the dominants in the subsequent encounters. These suggest that memory of defeated experience of subordinates is formed after the first encounter to change their behavior in the subsequent encounters. In rodents, previous studies using a social defeat paradigm suggested the involvement of the corticosteroid system in memory formation of defeated experience. In birds, however, the involvement of this system in the dominance formation remains unclear. This study investigated the effects of peripheral corticosteroid blocking on subordinates’ behavioral changes associated with the dominance formation in crows. For the experimental group, we injected metyrapone peripherally to the defeated individuals immediately after the first encounter. Defeated individuals of a control group received no injection. We compared the two groups base on the degree of the change of aggressive and of submissive behavior from the first to the subsequent two encounters. Although subordinates in the control group showed no aggression in the subsequent encounters, those in the experimental group retained aggression. No difference between the groups was found in submissive behavior. These results suggest the involvement of the corticosteroid system in memory-based suppression of aggressive behavior in subordinates.

In many species, the allocation of exploration and exploitation responses to environmental stimuli is important for survival. In this exploratory study, dogs (Canis familiaris) were tested whether they explore novel stimuli or not in a visual discrimination task using food reinforcers. Initially, the dogs were trained with two pairs of simultaneous visual discrimination tasks. Having achieved the learning criterion, they were presented with a pair of stimuli consisting of a novel stimulus and a previously reinforced stimulus on the probe trials. Dogs were reinforced by 50 % for novel stimuli and 100 % for the familiar stimuli. The proportions of responses to novel and familiar stimuli in probe trials were considered to reflect propensity for exploration and exploitation, respectively. As a result, the novel stimulus was selected overall more frequently in 22 of the total 30 probe trials across the five dogs tested (the binomial test, p = .016). Dogs prefer novel stimuli to familiar stimuli, suggesting that this species, with its reduced neophobia compared to wolves (Canis lupus), could allocate more responses to exploration. Comparisons among breeds or with wolves will be needed in future studies.

In everyday life, we stop on-going activity when we hear a scary sound. Conditioned suppression is a procedure to examine the effect of pavlovian conditioning on behavioral performance. Here we established the conditioned suppression procedure in head-fixed mice. First we trained mice on a fixed-time (FT) schedule using a head-fixed setup. We delivered a 10% sucrose solution every 10 seconds with a blunt tipped needle placed within licking distance of the mice. After the training, the mice showed anticipatory and consummatory licking. Second, we trained the mice with eye-blink delayed conditioning using an auditory stimulus and an air-puff delivery in the same head-fixed situation. We paired a 6000Hz tone for 1s presentation with 100 ms air-puff delivery to the face of the mice. Mice learned the relationship between the two stimuli, and showed the anticipatory eye-blink responses after the presentation of the tone. Finally, we occasionally presented the tone associated with the air-puff delivery while the mice perform the FT schedule. Licking of the mice was suppressed after the presentation of the tone. Combining this approach with pharmacological, optogenetic, and chemogenetic manipulations and single-unit or calcium imaging neuronal recording will pave a way forward to study the neuronal circuits underlying the conditioned suppression.

Predicting the timing of events is essential for survival in many animals including humans. Several theories state that interval timing and temporal properties of memory are closely related (e.g. Staddon, 2005). Systemic injections of drugs that cause memory deficits are known to reduce temporal accuracy and precision. However, the interpretation of previous experiments on timing studied with free-moving animals are confused, because factors of movement and interval timing are intermixed there. Here we examined the effects of pharmacological manipulations on timing behavior with head-fixed mice. We trained head-fixed mice on a temporal conditioning task with a peak procedure. After the training, the mice showed ramping anticipatory licking toward the timing of sucrose delivery, suggesting that mice can predict the timing of the reward. Pharmacological manipulations of scopolamine, a muscarinic cholinergic receptor antagonist, and MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist disrupted the temporal precision of anticipatory licking. We verified the effects of these pharmacological manipulations on timing behavior by comparing the results with spontaneous activities in an open-field task and maintenance, extinction, and re-acquisition of learned behavior in an auditory delay conditioning. Understanding the pharmacological basis of timing behavior allows us to unweave the intricate relationships between prediction, timing, movement, learning, and memory.

Dopamine is hypothesized to play multiple roles in (supra-second) interval timing, especially adjusting an internal clock's speed. As one target of the mesocortical dopamine projection in a rodent brain, the medial prefrontal cortex was also repetitively proved to participate in temporal control. However, in most of those research, temporal accuracy that is a critical property in the clock speed hypothesis, has not been evaluated. In the current experiment, we used a peak interval procedure to assess the effect of medial prefrontal D1 dopamine receptor (mPFC D1DR) inhibition (with SCH23390) on temporal accuracy and precision. As a result, only the low dose (0.5 μg) temporarily induced a rightward shift of the peak time and broadened the response curve, suggesting a transient decrease in clock speed. On the other hand, the high dose (1.5 μg) varied the trial-by-trial response time, indicating an impaired precision. These results manifest the dose-specific effects of the mPFC D1DR inhibition on temporal accuracy and precision.

We examined sex differences in helping behavior in prairie voles. An experimental apparatus consisted of a pool area and a ground area. Two to six prairie voles that were all littermates were housed together in cages. We formed pairs of littermate voles. One of a pair was assigned as a helper vole and the other was assigned as a soaked vole. There were four groups of all possible sex combinations (a male helps a male; a male helps a female; a female helps a female; a female helps a male). Each group consisted of seven pairs. A helper vole in the ground area rescued a soaked vole in the pool area by opening a circular door. In addition, we measured duration of huddling as an indicator of social attachment after the helper opened the door. The door-opening latency decreased as the progress of the task sessions, suggesting that prairie voles learn helping behavior. However, we could not find differences either in the latency of door-opening behavior nor in the duration of huddling among all of the groups. This suggests no sex differences in helping behavior toward a littermate. In the future, examination of helping behavior toward a stranger may be needed.

Ohkita, Nihei, Nishiyama, and Sawa (2018) revealed that riders feel a “sense of unity with horse[s] (Jinba-ittai in Japanese)” when riding due to the human-horse interaction in training. Additionally, we revealed that one component of Jinba-ittai was a sense of smooth interaction. (“We understand each other very well.”) Humans might come to perceive more of the horse’s mind through interaction with the horse.

The present study revealed differences in the perception of animals (humans, dogs, cats, and horses) between those who had dogs and/or cats and those who did not. We used a questionnaire from Gray et al. (2007), which allowed the assessment of how individuals perceive the minds of various entities from two dimensions “experience (e.g., capacity for anger)” and “agency (e.g., capacity for morals)” The factor scores of the experience of a dog (or cat) were higher in those who had dogs (or cats) than in those who had never had one. Factor scores for the agency of dogs and horses were higher in those who had cats than in those who had never had one. These results suggest that humans perceive more experience in dogs and cats by interacting with them. In contrast, there might be species differences in the effects of interaction on the perception of agency.

Group living animals form dominance hierarchies. A dominance hierarchy is a social structure that is described by an asymmetry in agonistic interactions between the group members. The rank of members in a dominance hierarchy has been studied with a focus on reproductive success. However, it remains unclear which member(s) is crucial to maintain a hierarchical structure in a fission-fusion society. One hypothesis is that the higher-ranked member plays a crucial role in maintaining the social structure by interacting with lower-ranking members. This hypothesis has been argued base on the observational study in various mammals and birds. Yet, not many studies have experimentally tested. This study aimed to test this hypothesis by the temporal removal of the top-ranked male from a captive group of large-billed crows (Corvus macrorhynchos). From group-housed crows those ranks of which were determined prior to the experiment, we temporarily removed the top-ranked individual and compared behaviors of remaining individuals during the removal with those before the removal. We found that the amount of subordinate’s sequential calls, assumed as a status vocal signal, increased during the removal. No such increase of calls was found during the removal of a middle-ranked individual. This result supports the hypothesis that the top-ranked individual accounts for the maintenance of the dominance hierarchy.

Recently, Urcuioli (2008) demonstrated symmetry in pigeons using a successive (go/no-go) matching-to-sample procedure and pointed out that one of the control variables is that pigeons continue to experience non-reinforced trials until later in the training. The present study replicated Urcuioli's experiment and examined the influence of non-reinforced trials through direct observation of behavior. Five pigeons were trained hue-form arbitrary, hue-hue identity, and form-form identity matching using successive matching-to-sample procedure. In the reinforced trials, the reinforcers were presented on a fixed-interval 5-s schedule. After the discrimination ratios stabilized at 0.8 or higher, each pigeon received the tests for form-hue symmetry. The results showed that 3/5 pigeons demonstrated the symmetry with larger differences in response rate between positive and negative trials--which is successful replication of Urcuioli. The direct observations revealed that such response rate differences corresponded to differences in the time spent engaged in other behaviors, rather than to differences in response patterns shaped under the fixed interval schedule. This latter results seems to enhance the validity of the symmetry in the successive matching-to-sample procedures.

Dysfunctions of body image are often observed in persons with autism spectrum disorder (ASD). We have developed a rubber tail task in mice by stroking a real tail and a rubber tail (Wada et al., 2016), aiming to evaluate dysfunctions of body image, and found that the rubber tail response was not obvious in Ca2+-dependent activator protein for secretion 2 (Caps2) KO mice (Wada et al., 2019), which show autistic-like phenotypes. On the other hand, SH3 and multiple ankyrin repeat domains 3 (Shank3) is known as one of the most popular autism-related genes. In present study, we investigated rubber tail responses of the Shank3 KO mice. After synchronous stroking of rubber and real tails, wild type mice responded as if their own tails were touched, when the rubber tails were grasped. In contrast, difference in the response rates between the synchronous and asynchronous stroking were not observed in Shank3 KO mice. The preliminary result was similar to that of Caps2 KO mice. This indicates dysfunctions in body ownership in ASD were partly mimicked in the mouse model of ASD, but the response rates seem to be low in the Shank3 KO mice, compared with wild type mice.

Domesticated animals commonly display low cortisol secretion, reduced aggression and juvenilized head known as the domestication syndrome. Previous studies have shown that domestic cats have low cortisol levels than wildcats; however, their behavior and morphology have not been investigated in a comparative way. In this study we compared facial morphology of four categories in cats: African wildcats (Felis lybica), feral mongrels, owned domestic mongrels, and owned domestic purebred cats (Felis catus). We measured their facial depth (nose length adjusted by distance between eyes) and eye angle. We also collected feces from owned domestic mongrels and owned domestic purebred cats to measure cortisol levels, and investigated behavioral characteristics by questionnaires to the owners. The results showed that face depth of domestic cats was shorter than that of African wildcats and the distance of owned domestic purebred cats was significantly shorter than that of owned domestic mongrels. In terms of the angle, owned domestic purebred cats was found to be lower than owned domestic mongrels. There were no significant differences in fecal cortisol levels, sociability, and aggression. These results suggest that domestication causes the facial morphology of domestic cats to be more juvenilized than African wildcats but further studies are needed to investigate its effects on their endocrine and behavior.

Biological motion (BM) perception critically contributes to of social recognition in humans, and those individuals with autism-spectrum disorder (ASD) have lower BM scores than typically developing children (Blake et al. 2003). Prenatal exposure of an anti-epileptic drug (sodium valproate, VPA) is reported to be a risk factor of ASD, presumably through its inhibitory action on histone deacetylases (HDACs). In a good accordance, in ovo injection of VPA on embryonic 14 days (~7 days before hatch) impairs social behaviors (Nishigori et al. 2013) and social predisposition (Sgadò et al. 2018) in post-hatch chicks, while sparing the imprinting (learned preference). In this study, we examined alternative mechanism rather than the epigenetic action of VPA, namely acute suppression of neural activities by comparing the effects of ketamine with those by VPA. Preliminary results showed that both VPA and ketamine effectively suppressed BM preference and imprinting, quantitatively not identically; VPA suppressed imprinting more, whereas ketamine’s suppression on BM preference was more potent. Infusion of VPA and ketamine on embryonic 18 days (~3 days before hatch) had weaker effect. These results suggest that neural activities during the late developmental stage are critical for induction of BM preference in early post-hatch period.

Behavior of rodents is much affected by their social environment. Here, we examined how social behavior in male mice is changed by housing condition. Mature male ICR mice were assigned into 3 conditions: group housing, living alone, and isolation after mating experience. More than 2 weeks after each housing started, the behavioral tests consisted of 3 weeks sessions (each comprised of 3 day repetitions) were conducted in an observation apparatus (square box, 45 x 45 cm) with the floor sheet of absorbent paper and a cylindrical stimulus cage (diameter of 10 cm) in the center. In each session, we recorded their response to the empty stimulus cage (1st session), with stranger males (2nd) or with estrous females (3rd), and measured nose-contact time to the stimulus cage and area size on scent marking (stained by ninhydrin reaction) for 5 min. All mice showed significantly longer nose-contact time to the cage with estrous female than that of empty or male, no matter which housing condition. On the other hand, sexually naive isolated males showed significantly larger scent marking when presented estrous females, but not males and empty, while group housing males showed almost no scent marking in any stimulus cage. In contrast, sexually experienced isolated males showed significantly larger scent marking in empty cage than the cage containing males or females. These results demonstrated that social behavior was affected by social environment in housing, and also by their mating experience.