Abstract list:

Keynote Speaker

Michael A. Fox

Dean, College of Natural Sciences,  University of Massachusetts Amherst

“Shedding light on mechanisms that wire the brain”

Distinct features of the visual world are transmitted from the retina to the brain through anatomically segregated circuits. Despite this being an organizing principle of visual pathways in mammals, we lack an understanding of the signaling mechanisms guiding axons of different types of retinal neurons into different regions of the brain, and in some cases segregated layers of those brain regions. Understanding this process, called axonal targeting, has been a major thrust in my lab for the past two decades. In a set of recent studies, we explored this question by identifying how axons from the ipsilateral retina innervate a specific lamina of the superior colliculus. Our studies reveal a unique cell-extracellular matrix (ECM) recognition mechanism that specifies precise targeting of these axons to the superior colliculus. Loss of this mechanism not only resulted in the absence of this eye-specific visual circuit, but it led to an impairment of innate predatory visual behavior.  

Poster Abstracts

1: Alexandrou-Majaj, Nadia

PBS, UMass

Testing transgenic strategies for the selective targeting and inactivation of the Indusium Griseum, and its effects on social memory

Alexandrou-Majaj N; Lalsare A; Durham J; Moorman D

First described in the 18th century, the indusium griseum (IG) has long been a region both contentious and overlooked. The IG is a thin column of gray matter overlying the rostrocaudal length of the corpus callosum (CC), spanning from the anterior hippocampal continuation (AHC), which wraps around the anterior genu of the CC, to the midbrain region where it terminates among the cortical layers overlying the hippocampal formation. Its narrow midline structure, combined with the belief that the IG is little more than a vestigial structure has led it to remain understudied until fairly recently. Morphologically and genetically, the IG bears striking similarities to two particular hippocampal subfields: the dentate gyrus (DG) and CA2. Although recent studies of protein expression have solidified the IG’s identity as a distinct hippocampal subfield, there has been little investigation into its function. Based on its genetic resemblance to area CA2, we hypothesize that the IG serves a similar function in the creation and consolidation of social memory. To address this hypothesis, we identified three molecular markers specific to the IG and bred corresponding transgenic mouse lines (Amigo2-Cre, IL16-eGFP, and Avpr1b-Cre) to selectively target the IG using Cre-dependent AAV. Injections in Amigo2-Cre mice showed strong expression in the IG, but also a high level of non-selective expression in the surrounding cortex and septal nuclei, excluding them from use in further studies. AAV delivered to the IG of IL16-eGFP and Avpr1b-Cre mice resulted in selective IG expression. To functionally test the impact of selective IG inactivation, we used AAV to drive IG neuronal expression of either inhibitory DREADDs or caspase, and tested their social memory in a 7-trial habituation/dishabituation task. Mice with IG inactivated during the task using either strategy were unable to habituate to the repeated presence of another mouse and did not increase exploration when subsequently presented with a novel mouse, thereby demonstrating a disruption of social learning. These results demonstrate novel strategies for targeting the indusium griseum, opening the door to new avenues of functional and behavioral research into social cognition. 

2: Amirault, Jayden

PBS, UMass

Investigating the changes in myelin dynamics in the mPFC following binge-drinking in adolescent mice

Amirault, Jayden; Senthilkumar, Rithika; Nouduri, Sirisha; Akli, Saïd; Teves, Catarina; Richardson, Heather

Studies in humans and rodents have shown that binge-drinking in can lead to cognitive impairments and loss of white matter and myelin. Myelin is produced by oligodendrocytes, which differentiate from oligodendrocyte precursor cells (OPCs), and wraps around axons, allowing for faster propagation of electrical impulses. The mechanisms by which myelin is lost due to alcohol consumption are not well understood. A recent study found that alcohol exposure in adults did not alter OPC cell density, suggesting that oligodendrocyte differentiation might be interrupted. We hypothesize that alcohol exposure in adolescence affect myelin through a similar mechanism. To study this, we used a transgenic mouse model (NG2-CreER:Tau-mGFP) that allows for tamoxifen-induced expression of GFP in OPCs, and administered alcohol for four weeks during adolescence using the drinking in the dark paradigm. We have performed immunohistochemistry and are using confocal imaging to visualize and quantify newly developing myelin and oligodendrocytes and preexisting myelin in the prefrontal cortex. This will help us understand how alcohol consumption interrupts the developmental process of myelin generation in adolescence. 

3: Anderson, Azaria

NSB UMASS

Activation of maternally-responsive estrogen receptor alpha-expressing cells in the medial preoptic area is reduced in mother rats exhibiting a depression-like phenotype

*A. A. ANDERSON, A. CONTRERAS, K. A. COPELAS, E. ROBINSON, M. PEREIRA;
Mothers who experience postpartum depression often exhibit deficits in parenting. However, the brain mechanisms by which postpartum depression impact parenting abilities are not well understood. Our prior work using the Wistar-Kyoto (WKY) well-validated animal model of depression revealed that, consistent with clinical reports, deficits in maternal behavior in WKY mothers are associated with increased peripartum levels of the steroid hormone estradiol. In addition, our prior research showed that chemogenetic activation of the medial preoptic area (mPOA), a brain region essential for maternal behavior, in WKY mothers ameliorates deficits in parenting and biases choice toward pup-associated cues in a pup-induced conditioned place preference (CPP). The goal of the present study was to examine whether hyporesponsiveness to the stimulatory effects of estradiol in the mPOA underlies the deficits in maternal motivation in WKY mothers. To this aim, we used immunohistochemistry for estrogen receptor alpha (ERα) and cFos (a marker of neuronal activity) to examine the expression levels of ERα in maternally-responsive neurons in the mPOA of WKY and control Sprague-Dawley (SD) mother. An additional experiment examined the expression of ERα in mPOA cells that are activated when WKY mothers expressed a pup-CPP versus when they did not. As expected, and consistent with our prior results, WKY mothers exhibited severe deficits in parenting and reduced pup-CPP compared with control SD mother rats. In addition, these maternal motivation deficits in WKY mothers were associated with altered activation of mPOA cells containing ERα. Together, the results suggest that estradiol-mediated altered activity of the mPOA may underlie depression-related parenting deficits.

4: Copelas, Katie

Psychological and Brain Sciences, UMass Amherst

Chemogenetic inhibition of medial preoptic area projections to the infralimbic cortex impairs maternal sensitivity in rats

Copelas K., Pereira M.

Maternal behavior that is sensitive to the needs of the offspring in everyday interactions is essential for the healthy development and well-being in mammals. However, the brain mechanisms that allow the critical maternal ability to dynamically couple caregiving and affective interactions to resolve the needs of their offspring (referred to here as maternal sensitivity) are not well understood. Our prior work shows that the medial preoptic area (mPOA), a critical node of the circuitry regulating maternal behavior, is required for maternal sensitivity. The objective of this study was to determine the role of the mPOA neurons projecting to the infralimbic medial prefrontal cortex, a critical site involved in cognitive and executive functions necessary for optimal selection of behaviors, in maternal sensitivity. To this aim, we used an intersectional viral strategy to inhibit monosynaptic communication between mPOA and IL neurons during maternal interaction with offspring with varying needs. Primiparous female rats received Cre-dependent hM4Di Designer Receptors Exclusively Activated by Designer Drugs (DREADs) into the mPOA, combined with retrograde AAV expressing Cre recombinase into the IL before mating. Maternal behavior testing occurred on postpartum days 7 and 8, 6-8 weeks after viral infusions. The study used a within-subject design to evaluate mothers interacting with offspring with varying needs following CNO inhibition of IL-projecting mPOA neurons. Our findings show that chemogenetic inactivation of IL-projecting mPOA neurons disrupts the ability of multiparous mothers to dynamically modify caregiving decisions and time commitment to resolve the needs of their offspring, highly contrasting the attuned behavior of control mothers. Together, this new work expands our understanding of the mPOA contribution to the expression of sensitive caregiving decisions.

5: DeAmicis, Sarah

Biology Department, UMass Amherst

A connectomics approach to determine the neural architecture of the chemosensory system of the gastropod mollusc Berghia stephanieae 

DeAmicis S, Dhiman K, Cook A, Gandikote N, Glover A, Sant H, Katz P

Although the chemosensory system in gastropod molluscs is associated with behavior and decision making, little is known about its neural architecture. Advances in imaging and computational approaches allow the reconstruction of neuronal connectivity from serially sectioned brains. Here, we took such a connectomics approach to determine the neuronal architecture and connectivity in the rhinophore ganglion (rhg), which sits at the base of the rhinophore, the chemosensory appendage, in the nudibranch, Berghia stephanieae. We segmented and made 3D reconstructions of several cells from electron micrographic images obtained from a rhg that was serially cut into 2175 sections at 33 nm thickness and imaged at 4x4 nm lateral resolution. The rhg had a variety of regions including distinctive clusters of somata, axon tracts, and neuropil. We discovered possible non-neuronal cells, interneurons and projection neurons. Additionally, we identified non-branching axons possibly projecting from the cerebral ganglion. Across this variety of neurons, distinct characteristics were observed, including electron-dense granules and vesicles of different sizes. Machine learning algorithms will be applied to automatically segment all the cells to provide a first draft of the connectome. A complete connectome of this enigmatic ganglion will provide insights into its structural organization, which is likely to be involved in higher order olfactory processing.

6: English, Jay

MCB, Umass Amherst

Electrophysiological Characterization of Autism Patient Derived Induced Neurons in a Mixed Glutamatergic-GABAergic Culture Scheme

English J, McSweeney D, Howell E, Sebastian R, Ribbe F, Geng J, Sharf T, Pang Z, Pak C

Autism spectrum disorders (ASDs) are a group of related neurodevelopmental disorders characterized by learning disability, hyper fixation, sensitivity to stimuli, and social impairment. Currently, there are no effective treatments for ASDs and the mechanisms by which they develop are poorly understood. Studies indicate pathology stems largely from gene by environment interactions, with dysregulation of over 100 genes associated with higher risk for developing ASDs, most of which are involved in either gene regulation or neuronal communication. One such gene, NRXN1, encodes neurexin 1 (NRXN1), a presynaptic cell adhesion molecular important for synapse specification and maintenance. Albeit rare, heterozygous deletions of this gene have been found to occur at higher rates in ASD individuals versus the general population. The NRXN1 gene has six canonical splice sites and three alternative promoters, which in combination with post-translational modifications can encode thousands of possible splice variants. The composition and structure of the resulting presynaptic NRXN1 isoforms dictate which postsynaptic ligands NRXN1 can interact with, conferring synaptic specificity and function. Using whole-cell patch clamp electrophysiology and High-Density Multi-Electrode Arrays (HD-MEAs), we have undertaken a comprehensive electrophysiological characterization of three novel ASD patient induced pluripotent stem cell (iPSC) derived induced neurons (iNs) paired with healthy control donors, as well as an isogenic conditional heterozygous NRXN1 knockout iN system in a mixed glutamatergic-GABAergic 2D culturing scheme. Results indicate changes in excitatory-inhibitory synaptic signaling and a disruption in neuronal network communication. Further experiments will probe changes in alternative splicing in the disease background and seek to elucidate the mechanisms by which these occur and how they contribute to disorder development. 

7: Falcy, Brennan

NSB, UMass Amherst 

Metabolic Disruption Following Circadian Desynchronization is Mediated by Endocannabinoid Signaling

Falcy B, Phillips D, Denaroso G, Pearson G, Wang J, Karatsoreos I

Central and peripheral endocannabinoid (eCB) signaling modulates metabolism, and manipulating eCBs can ameliorate symptoms of metabolic dysfunction. Circadian (daily) rhythms are critical for homeostasis, including normal metabolism, and disruption of these rhythms, genetically or environmentally, can lead to cardiometabolic disease in both human and non-human animals. In humans, sleep misalignment prompts an increase in circulating eCBs. We have shown that environmental circadian desynchronization (ECD), by housing mice in 20h cycles (10h light – 10h dark), leads to weight gain and altered metabolic hormone levels. Our goal was to determine if eCBs are a causal connection between ECD and metabolic disruption.

Male and female C57BL/6J global cannabinoid type 1 receptor (CB1r) or liver specific (LCB1r) WT and KO mice (8-10wks) were used. Following 7d “baseline” (T24) conditions mice were exposed to ECD (T20; 10h light, 10h dark) for 42d. Gas calorimetry, food and water intake, body weight, and activity were continuously measured using a TSE Phenomaster. For transcriptomics, liver RNA extracted, and qRT-PCR undertaken. Plasma measures were assessed using multiplexed Luminex MagPix kits. Data analysis and statistics were undertaken with R.

ECD causes significant changes in rhythms of feeding, drinking, locomotor activity and RER. Global CB1r KO mice are largely protected from many of the negative effects of ECD (e.g., weight, plasma measures), even though ECD effects on these behaviors are similar in both strains. The contribution of LCB1r KO, is mixed and will be discussed in detail.

Global CB1r KO male mice are protected against the adverse metabolic effects of ECD, but this does not appear to be mediated through a difference in gross behaviors. Additionally, data show LCB1r KO animals are also resistant to the metabolic effects of ECD, suggesting that the protective effect of CB1r KO likely includes a peripherally mediated effect.

8: Florees Bonilla, Annabelle

Psychological and Brain Science, UMass

Determine how adolescent alcohol drinking alters corticotropin releasing factor (CRF) and axonal myelination in the central amygdala in adulthood in male and female mice

Flores-Bonilla A, Akli S, Senthikumar R, De Oliveira B, Rajvanshi A, Amira N, Richardson HN.

Neural circuits involved in regulating stress responses undergo maturational processes during adolescence including myelination of axons, and new myelin formation may also be an adaptive and experience-driven process. Indeed, early life adversity leads to higher functional connectivity between the prefrontal cortex and central amygdala (CeA) later in adulthood, which is accompanied by heightened corticotropin releasing factor (CRF) stress peptide in this region. Alternatively, chronic alcohol exposure reduces myelin and oligodendrocyte gene expression and CRF peptide levels in the CeA, but these effects may rebound following removal of alcohol. The goal of the current study was to test the following hypotheses: 1) new myelin is added to CeA axons following a history of adolescent alcohol drinking, and 2) a proportion of these myelinated axons contain CRF peptide. We used our inducible transgenic mouse reporter line (NG2CreERt: Tau-mGFP) to tag and track oligodendrocytes forming new myelin in the CeA following adolescent binge drinking. Adolescent male and female mice were exposed to 20% v/v alcohol or water (n=9-11 per group) starting at postnatal day 28 using a modified drinking in the dark (DID) paradigm for 2 weeks. Cumulatively, mice consumed an average of 38.66 g/kg of alcohol with an average of 4.16 g/kg/4h per session. Following 2 months of abstinence, mice were intracardially perfused, and brains were extracted and sectioned. Immunohistochemistry was used to fluorescently co-label GFP (“new myelin”) and CRF. Our results indicate that myelinated axons coming into or going out from the CeA is colocalized with CRF peptide expression. Further analyses will determine if a history of alcohol exposure during adolescence followed by long-term abstinence is sufficient to induce increase myelination of these CeA axons, which could lead to changes in stress responsivity. 

9: García Álvarez, Iván

Psychology and Brain Sciences, UMass Amherst

Role of rat frontal association area in response inhibition in a GoNoGo task

Iván García Álvarez, Christopher G. Perk, David E. Moorman

The prefrontal cortex is well known to be involved in response inhibition. However, the role of the frontal association area (FrA), the most anterior part of this region in rodents has not been characterized. To investigate the role of this brain region in response inhibition we bilaterally injected adeno-associated viruses containing inhibitory Designer Receptors Activated Only by Designer Drugs (DREADD) into the FrA of adult Long-Evans rats (n = 6, 200 nl/hemisphere) and implanted a stimulating electrode onto the right median forebrain bundle (MFB), to enable intra-cranial self-stimulation behavior.

Animals were trained to perform a Go No-Go task (50:50 trial ratio) using an operant chamber with 2 nose-poke holes, each positioned on the left and right side of one wall. During Go trials animals were required to enter the left nose-poke when illuminated, which produced a 500 ms tone cue (1kHz). Rats were required to hold the nose-poke for the duration of the cue, immediately after which the light extinguished and the right nose-poke would illuminate. Rats received MBF stimulation, accompanied by three tone pips (100ms each, 2.5kHz), if they entered the right nose-poke within 2s of it becoming illuminated. During No-Go trials, rats were required to enter the illuminated left nose-poke immediately after which a unique 500ms cue tone (3.5kHz) indicated that they needed to hold for an additional 500ms after the termination of the compound tone/light cue to receive MFB stimulation and tone pips.

We found DREADD-mediated inhibition of the FrA via the ligand deschloroclozapine (DCZ) increased Go poke hold times vs. dimethyl sulfoxide (DMSO) vehicle. DCZ significantly increased hold times (DCZ, 574 ± 32ms, DMSO, 558 ± 23ms, t(5) = 3.378, p=0.0197), and we also saw a trend towards reduced Go tone errors during FrA inactivation (DCZ, 15.3 ± 3.0% of total Go trials, DMSO, 19.6 ± 4.9%, t(5)=2.327, p=0.0675). DCZ had no effect on measures of No-Go trial performance. These data indicate a specific role for FrA in improving the initiation window of behavior required to obtain positive reinforcement.

10: Harmon, Leah

Departments of Neuroscience and Neurology, Yale University

Methods to image the dopamine transporter (DAT) in vitro and its applications in Parkinson's disease research

Harmon, LE; Khezerlou, E; Saenz, J; Brown, C; Pan, PY; Chandra, SS

Parkinson's Disease (PD) is characterized by the selective degeneration of dopaminergic neurons (DA neurons) in the substantia nigra pars compacta. The underlying mechanisms for this dopaminergic vulnerability are incompletely understood but may involve defects in sorting and recycling at the synapse. Recently, our lab observed that the dopamine transporter (DAT) appears to be trapped in axonal membrane deformities in a PD mouse model lacking auxilin, an endocytic chaperone. This DAT mislocalization is accompanied by delayed DA reuptake, suggesting a link between endocytic proteins, trafficking/recycling of DAT, and dopaminergic vulnerability in PD. Previous studies have observed DAT trafficking and recycling via immunostaining and localization experiments with time-course analyses. However, live imaging of DAT in vitro will contribute greatly to our understanding of DAT dynamics. pHluorins, pH-sensitive GFPs, are an effective tool for studying endo- and exocytosis of cell surface proteins. Therefore, in conjunction with the Pan Lab, we have developed a mouse DAT-pHluorin probe (mDAT-phluorin), in which a superecliptic pHluorin is inserted into the extracellular domain of mouse DAT. The mDAT-pHluorin has been validated in N2A and primary neuronal cells to ensure proper expression and function. In N2A cells, the fraction of surface mDAT-pHluorin and its vesicular pH is comparable to the Pan Lab's previously validated human DAT-pHluorin. mDAT-pHluorin demonstrated fluorescence decreases in response to PMA (phorbol myristate acetate) and amphetamine, signifying its sensitivity to induced internalization and substrate binding, respectively. In neurons, mDAT-pHluorin also showed robust expression and pH responsiveness in the cell body, axons, and dendrites. One limitation of pHluorins is their loss of fluorescence once internalized. As an alternative method, we are employing PRIME (probe incorporation mediated by enzymes) imaging, in which a ligand acceptor peptide is fused to DAT (LAP-DAT), allowing its ligation to a fluorescent probe. We have successfully synthesized all necessary components for PRIME, include a picolyl azide compound necessary for ligation and shown that LAP-DAT colocalizes with DAT antibodies in transfected HEK293T cells, validating the specificity of fluorophore ligation. Our next step will be to perform PRIME in primary dopaminergic neurons derived from mouse substantia nigra. This will allow us to live-track DAT upon internalization in conjunction with organelle markers and to perform multi-protein immunofluorescence in fixed cells. Use of these DAT imaging techniques in primary neurons from auxilin knockout mice, other PD mice, and patient iPSC-derived DA neurons will allow us to understand whether DAT recycling and trafficking defects are present across PD models and possibly contributing to dopaminergic vulnerability. 

11: Kamara, Vanessa

Biomedical Engineering, WPI

Influence of Orientation on Neural Excitability During Electrical Stimulation in C. elegans

Kamara, V; Rothschild, J; Albrecht, D

Deep brain stimulation (DBS) has emerged as a promising therapeutic approach for a range of neurodegenerative and psychiatric disorders not limited to Parkinson’s disorder, obsessive-compulsive disorder, and epilepsy. However, as the human brain is an incredibly complex and dynamic organ, the physiological mechanisms underlying therapeutic effects remain largely unknown. C. elegans, a transparent nematode that’s previously been used as an animal model for Parkinson’s and epilepsy allows for the study of neurological modulation at the single-neuron level. The C. elegans strain used features GCaMP2.2b and Chrimson channel rhodopsin (Chr) within its AWA neuron; Chr allows for depolarization of the neuron using red light and GCaMP allows for quantification of signal dynamics using fluorescent imaging. Microfluidic arrays forced animals into one of two orientations removing orientation variability. This study utilized computer-automated electrical and optical stimulation to examine how electrical stimulation modulates the responses of optogenetically stimulated neurons. Prior to electrical stimulation typical response dynamics were determined using red light stimulation. Modulation during electrical stimulation was assessed by comparing basal responses to responses generated during the application of electrical stimulation. As a physiologically relevant voltage amplitude has yet to be determined in this model, a voltage sweep from 0-15V in increments of 3V was completed using a stimulation waveform with a duty cycle of 25% and a frequency of 80Hz. It was found that applying a voltage greater than 6V induces basal fluctuations in membrane potential indicative of direct depolarization. Animals oriented with the head closer to the positive electrode (head positive) experienced an increase in basal potential while animals facing the opposite direction (head negative) experienced a decrease in basal potential. Head positive (negative) animals showcased increased (decreased) maximal potentials and excitability for voltages greater than 3V. Both orientations exhibited history dependence and adaptation of response modulation during electrical stimulation. These results showcase that electrical stimulation of C. elegans generates orientation-dependent changes in neural response dynamics as seen in humans and other model systems.

12: Lê, Jason

Biology, University of Massachusetts Amherst

Investigating the role of AgRP neurons in the metabolic gating of reproduction during caloric restriction and postpartum lactation 

Le J, Gangireddy K, Solipa J, Padilla SL

Chronic undernutrition and negative energy balance during lactation are metabolic stressors that modulate behavior and reproductive health. Agouti-related peptide (AgRP)-expressing neurons are essential for mediating feeding behavior and have been implicated in leptin-associated infertility demonstrated by the loss of estrous cyclicity. AgRP neurons are activated during starvation and attenuate fertility by inhibiting Kiss1 neuron signaling. AgRP neurons may be ablated using diphtheria toxin (DT) in transgenic mice that express the human form of the diphtheria toxin receptor (AgrphDtr). Ablating AgRP neurons results in lethal aphagia in adult mice, however, if AgRP neurons are ablated earlier in development (juvenile mice), animals survive and have a similar growth trajectory to non-ablated controls. In this study, we examine the effect of ablating AgRP neurons in females during two states of metabolic stress; 1) caloric restriction, and 2) lactation. We compared two cohorts of mice in which diphtheria was administered to ablate AgRP neurons: 1) adult mice, and 2) adolescent mice. Consistent with previous literature, DT-induced ablation of AgRP neurons in adult animals results in a cessation of feeding and mortality. DT ablation in adolescent animals did not alter mortality. Our results indicate that juvenile ablated mice are resistant to caloric restriction-associated infertility. If AgRP neurons are necessary to gate the reproductive axis in the face of metabolic stress, then we predict a similar restoration of fertility in females during the negative energy balance of lactation. 

13: Martinez-Martin, Beatriz 

Molecular and Cellular Biology, University of Massachusetts-Amherst

Engineering Next Generation Cerebral Organoids

Beatriz Martinez-Martin, Narciso Pavon, Yubing Sun, ChangHui Pak

Neurodevelopmental disorders historically have been difficult to study and treat due to limitations in access to human samples and relatability of non-human disease models. Rodent brains have been the primary model for studying these disorders, but rodent brains develop differently from human brains in some key ways, limiting their translatability to clinical settings. Brain organoids derived from human induced pluripotent stem cells (iPSCs) have been explored for the potential to model neurodevelopmental brain disorders, because they recapitulate early embryonic disease phenotypes and reproduce some key developing brain structural features, like cortical layering and proliferative zones. Although organoids show much promise as a neurodevelopmental disease model, organoids are still not the perfect replica of the human brain, including, but not limited to, the lack of vascularization and effective delivery of nutrients to the inner layers of the organoid, leading to a necrotic core. It also remains a challenge to develop brain organoids that are not heterogeneous, a result from the stochastic nature of iPSC differentiation. Currently, quantifying electrical properties during development is limited by measurement techniques that do not provide long-term stable 3D bioelectrical interfaces with developing organoids. In light of these challenges, this study aims to enhance the brain organoid model by addressing current limitations, striving for greater homogeneity and electrical activity. Cerebral brain organoids were grown using an unguided differentiation approach. Biosilk was employed to simulate an extracellular matrix, facilitating the diffusion of small molecules throughout the organoid and mitigating the necrotic core, ultimately promoting a more homogeneous cell population. The increased diffusion of molecules is anticipated to enhance overall organoid activity. To assess the efficacy of the biosilk protocol in enhancing organoid development, we conducted calcium imaging using the equipment located at the Light Microscopy Center (A1R25) to capture heightened activity.

14: Naughton, Emily

Psychological and Brain Sciences, University of Massachusetts Amherst

Tracking New Myelin Formation During Adolescence and Across the Lifespan

De Anda Gamboa, C; Naughton, E; Schmitt, M; Flores Bonilla, A; Kelly, D; Akli, S; Bergan, J; Richardson, H

In periods of rapid growth and development, myelin-producing glial cells (oligodendrocytes, OLs) wrap lipid-rich myelin segments around axons, supporting fast communication across different regions of the brain. White matter increases in frontotemporal brain regions during adolescence, and this corresponds with improvements in executive functioning, complex cognitive processing, and stress regulation. These functions are impacted early in degenerative diseases like Frontotemporal Dementia and Alzheimer’s Disease, suggesting the integrity of white matter tracts interconnecting these regions may be impaired. It is therefore important to better understand the cellular dynamics of OLs during adolescence and the temporal and spatial patterns of new myelin formation during this critical developmental period. A major challenge in the field has been visualizing and tracking de novo myelin sheath formation. Herein we have successfully distinguished between new and previously formed myelin using a double transgenic conditional mouse reporter line (NG2-CreERt: Tau-mGFP). By combining this approach with double/triple immunofluorescent labeling and confocal imaging, we have discovered that there is rapid differentiation of OLs and formation of new myelin throughout frontotemporal white matter regions including the forceps minor of the corpus callosum, the anterior commissure, as well as white matter tracts of the hippocampus and amygdala. Using CLARITY and light sheet microscopy we generated a 3D map of myelinated tracts that were formed during adolescence and remain in these frontotemporal regions well into adulthood at 6 months of age. The cellular dynamics of OLs may change across the lifespan and affect myelin maintenance and the function of these frontotemporal circuits, leaving these pathways susceptible to degeneration. These findings could have significant implications for identifying targets and timelines of therapeutic intervention as individuals age.

15. Noh, Eunsol

PBS (NSB), College of Natural Sciences

Associations between Sleep Slow Oscillation-Spindle Coupling and Declarative Memory in Early Childhood 

Sanna L, Eunsol N, Tracy R and Rebecca M.C.S

INTRODUCTION: Naps benefit memory in early childhood (3-5 years) even as children transition from biphasic to monophasic sleep. This memory benefit is thought to reflect sleep-dependent memory consolidation orchestrated by three oscillations in the sleep EEG1. Recent studies have observed the simultaneous activity of slow oscillations (SOs) and sleep spindles (SPs), referred to as SO-SP coupling, during childhood2,3,4. This coupling may be strengthened with development as it has been shown to be greater in adolescence relative to childhood4. Further, coupling strength has been shown to be positively related to memory consolidation3,4. How SO-SP coupling strength changes during early childhood and how it relates to memory consolidation remains unexamined. We hypothesize that coupling strength increases with development, thus benefiting memory consolidation. Alternatively, naps may not be sufficient to observe changes in coupling strength. METHODS: Study Design: This is a preliminary analysis of data from a longitudinal study examining polysomnography (PSG), memory, and brain development. Important to current analyses, there were 2-3 sleep and memory assessments over the course of a year (Wave 1: baseline; Wave 2: 6 months after Wave 1; and Wave 3: 12 months after Wave 1). Analysis involves two groups - children with Wave 1 and Wave 2 data (W1-2 group) and a separate group of children with Wave 2 and Wave 3 data (W2-3 group). Participants: Participants were 20 preschool-aged children. The W1-2 group included 10 children (6 female, Mage = 4.03, SD = 0.60 at Wave 1) and the W2-3 group also included 10 children (5 female, Mage = 4.66, SD = 0.41 at Wave 2). Memory task: The task was a visuospatial learning task, similar to the game “Memory”5. Children learned image locations on a grid (see below). Subsequently, the images were “turned over” and children located the position of each image. Images were presented again, one at a time, and children were asked to recall the location of the corresponding image. To examine memory consolidation over the nap, change in memory performance was calculated as accuracy at Delayed recall – accuracy at Immediate recall. PSG acquisition: PSG was recorded over the mid-day nap (~2 hours starting around 12pm) using a 14-electrode Embletta NPR ambulatory PSG system. Event Detection: Spectral analysis focused on frontal, frontocentral and central regions. SOs were detected in the frequency range of 0.16-1.25 Hz and sleep spindles (10-13 Hz) were detected ±1.5 Hz around the center peak of 11.5 Hz5. Artifact-free SO segments (i.e., ± 2.5 sec around the SO trough) were extracted from the raw signal. Phase-amplitude coupling7,8,9: The SO segments were filtered in the SO frequency band (0.16-1.25 Hz) and then the phase angle was detected using the Hilbert transform function. The same segments were also filtered in the SP frequency band (10-13 Hz) and the amplitude was extracted using the Hilbert transform function. Phase locking of SOs at the peak amplitude of SPs was assessed in each region of interest within each participant. From the mean SO phase in each region in each participant, we conducted circular statistics in MATLAB to calculate the resultant vector length, which indicates the strength of phase locking. RESULTS: What is slow oscillation-spindle (SO-SP) coupling strength? Fig A is an example of the fine-tuned coupling between SOs and SPs. A single subject will have a range of coupling of SO-SP events (Fig B, blue histogram) with the mean of these (angle of the pink line) representing their preferred phase and the variability of these (length of the pink line) reflecting the coupling strength. Does coupling strength increase with development? We did not observe a significant change in coupling strength from Wave 1 to Wave 2 (ps > 0.67; above left). This remained the case even after controlling for age and gender (ps > 0.28). In the W2-3 group, while coupling strength overall was not significantly different between Wave 2 and Wave 3 (ps > 0.41; above right), there was a main effect of gender such that males had greater coupling strength in frontal derivations than females at Wave 2 (F(1,9) = 6.93, p = 0.03). How does coupling strength relate to memory consolidation over the nap? In the W1-2 group, coupling strength at Wave 1 was not associated with memory consolidation over the nap at Wave 1. Similarly, coupling strength at Wave 2 was not associated with memory consolidation over the nap at Wave 2. In the W2-3 group, coupling strength in central derivations at Wave 2 was marginally and negatively associated with memory consolidation over the nap at Wave 2 (r = -0.62, p = 0.054). However, at Wave 3, coupling strength in frontal and fronto-central regions was positively associated with memory consolidation over the nap (ps < 0.013). What is coupling strength at each ROI at each Wave? The figure at the right illustrates coupling strength for frontal, fronto-central, and central regions at each wave. There was no systematic change in coupling strength across waves. DISCUSSION: Our findings indicate that SO-SP coupling strength did not significantly change in the developing brain over a year. However, by Wave 3, we see that coupling strength in frontal regions during a nap became positively related to memory consolidation over the nap. This provides preliminary support that SO-SP coupling strength in naps in early childhood may contribute to the strength of memory consolidation to some extent. Further, our results indicate that males had greater frontal strength than females. This finding is in line with work highlighting that between the ages of 12-14 years, there is a longitudinal increase in SP density in males, 31% greater compared to females10. This suggests that there may be sex differences in the maturational trajectories of SPs that may affect coupling strength of SO-SP events in early childhood. Overall, these results suggest that physiological markers of brain and memory development may undergo changes during the biphasic to monophasic sleep transition. Specifically, these changes may reflect a molding of a more efficient frontal neural network that benefits memory consolidation. Future research with a greater sample size will allow us to disentangle effects of sex and nap transition status on coupling strength and the relationship between strength and memory consolidation. 

16: Pavon, Narciso 

Department of Biochemistry and Molecular Biology

Patterning ganglionic eminences in developing human brain organoids using morphogen gradient inducing device

Pavon, N; Diep, K; Yang, F; Sebastian, R; Martinex-Martin, B; Ranjan, R; Sun, Y; Pak, C

In early neurodevelopment, the central nervous system is established through the coordination of various neural organizers directing tissue patterning and cell differentiation. Better recapitulation of morphogen gradient production and signaling will be crucial for establishing improved developmental models of the brain in vitro. Here, we developed a method by assembling polydimethylsiloxane (PDMS) devices capable of generating a sustained chemical gradient to produce patterned brain organoids, which we termed Morphogen-gradient Induced Brain Organoids (MIBOs). At 3.5 weeks, MIBOs replicated Dorsal-Ventral patterning observed in the Ganglionic Eminence (GE). Analysis of matured MIBOs through single-cell RNA sequencing revealed distinct Dorsal GE derived CALB2+ interneurons (INs), Medium Spiny Neurons (MSNs), and MGE derived cell types. Finally, we demonstrate long term culturing capabilities with MIBOs maintaining stable neural activity in cultures grown up to 5.5 months. MIBOs demonstrate a versatile approach for generating spatially patterned brain organoids for embryonic development and disease modeling.

17: Pearson, Gregory

Neuroscience & Behavior, UMass Amherst

 Intranasal poly(I:C)-induced neuroimmune responses are primed by time of day

Pearson G; Santos N, Wang J, Falcy B, Gottwals S, Denaroso G, Akli S, Karatsoreos I

BACKGROUND. Neuroimmune responses are critical for resilience against neurotropic infections and can be modulated by time of day. Here, we investigate how time of day impacts neuroimmune responses of the olfactory bulb (OB), the site of neurotropic virus entry into the brain via the olfactory pathway. Our preliminary work demonstrated that 20% of the neuroinflammation-related transcriptional profile in the OB is rhythmically expressed. Given these daily baseline changes, we hypothesized that neuroimmune responses of the OB to an intranasal virus-like challenge would be primed by time of day.

METHODS. For Experiment 1, we intranasally challenged male mice at the start of the resting phase (ZT0) or the start of the active phase (ZT12) with poly(I:C) and collected tissues at 3-, 12-, and 24-hours post-inoculation. OB transcriptional responses were measured using NanoString technology. For Experiment 2, we intranasally challenged male mice with vehicle or poly(I:C) at ZT0 or ZT12. We then isolated OB microglia at 24 hours post-inoculation and used imaging flow cytometry to analyze microglia.

RESULTS. For Experiment 1, we determined that time of day altered the OB’s neuroinflammation-related transcriptional response to intranasal poly(I:C). Specifically, intranasal poly(I:C) induced antiviral and innate immune pathway responses in the olfactory bulb, and these responses unfolded more rapidly in mice challenged at ZT12 compared to ZT0. For Experiment 2, we analyzed a population of cells isolated from OBs that were characteristic of microglia (CD11b+, CD45low). This population of microglia consisted of 670±94 cells, including 64±7% that were positive for P2RY12, a microglia-specific marker. Among other findings, time of day altered the effect of intranasal poly(I:C) on CD45 expression by OB microglia.

CONCLUSION. Time of day primes the OB to mount differential neuroimmune responses to intranasal inflammatory stimuli. This priming may provide a gating mechanism underlying differential susceptibility to neurotropic virus exposure via the nasal route. 

18: Proskauer, Lydia

BMB

The role of CASK in canonical Wnt signaling during forebrain development

Proskauer L., McSweeney D., Ortiz-Gonzalez X., Pak C.

The early development of the brain is a highly intricate process involving precise coordination of specific transcription factors and regulatory mechanisms that determine cell fate and brain structuring. Disruptions in these processes can lead to a wide range of neurodevelopmental disorders (NDDs), including autism spectrum disorders (ASDs) and schizophrenia. Unfortunately, due to the inaccessibility of tissue samples at early developmental stages, NDDs have proven difficult to study in humans. To combat this problem, the Pak lab employs transcription factor based guided differentiation techniques to generate neural cell types from human embryonic stem cells (hESCs) and human induced pluripotent stem cells (iPSCs). These induced neurons (iNs) can be used to shed light on the genetic and mechanistic drivers of NDDs in representative human genetic backgrounds. Here, we use cortical excitatory iNs to study calcium/calmodulin-dependent serine protein kinase (CASK), an X-linked pseudokinase which has been linked to numerous NDDs, such as ASDs, microcephaly with pontine and cerebellar hypoplasia (MICPCH), and various intellectual disabilities. CASK is generally thought of as a synaptic scaffolding molecule, however, its function varies greatly across developmental stages. During neuronal growth and maturation, CASK has been shown to be important for the transcriptional activation of genes necessary for cortical development. In mature neurons that have formed synapses, the scaffolding function of CASK aids in neurotransmitter release is required for successful synaptic signaling. While the importance of CASK in neurodevelopment is apparent, the exact mechanisms through which CASK mutations lead to such a wide range of NDDs are still unclear. Previous bulk RNA sequencing (RNAseq) of immature CASK deficient iNs (CASK-KO) performed by our lab suggests hyperactivity of the Wnt signaling pathway in these samples. While Wnt signaling is known to be an important pathway in facilitating cell division and early brain patterning, it has not previously been linked to CASK. Further investigation of this novel finding is essential for the understanding of CASK-related syndromes and generation of potential treatment strategies. Here, protein level analysis of CRISPR/Cas9 engineered CASK-KO iNs supports Wnt hyperactivity in response to CASK deficiency. Additionally, immunoprecipitation paired with mass spectrometry (IP-LC-MS/MS) identifies heterogeneous nuclear ribonucleoprotein U (HNRNPU), which has previously been implicated in Wnt signaling, as a putative CASK binding partner. Further work characterizing this novel link in iNs generated from both engineered CASK-KO hESCs and CASK patient derived iPSCs will help contribute to the understanding of a diverse range of NDDs. 

19: Ragoonaden, Shanthini

Mount Holyoke College

Maternal Allergic Asthma and IL-4 Signaling: Impact on Offspring Neurodevelopment and Behavior

Ragoonaden S., Schwartzer J.J

Introduction. Clinical studies have shown that allergic asthma during pregnancy is associated with an increased risk of neurodevelopmental and neuropsychiatric disorders in offspring. It is hypothesized that maternal interleukin-4 (IL-4) signaling is a causal mechanism linking maternal allergic asthma (MAA) to offspring neurodevelopmental deficits.

Methods. To test the role of maternal IL-4 in offspring brain development, we induce an allergic asthma response in pregnant C57Bl/6J and IL-4 Knockout (KO) mice on gestational days 9.5, 12.5, and 17.5. Offspring were evaluated for differences in arousal, social, motor, and cognitive behavioral tasks.

Results. We observed behavioral deficits in social interaction and memory performance in C57 offspring born from MAA-exposed dams compared to genotype-matched controls. However, these behavioral deficits were not present in IL4 KO offspring of either MAA or control dams.

Discussion. Our findings suggest a causal link between IL-4 signaling, a critical factor in the activation of allergic asthma inflammation, and neurodevelopmental deficits in offspring from MAA. Future studies should focus on the impact of transient elevations in IL4 signaling during critical developmental windows and their effects on offspring neurodevelopmental deficits.

20: Robinson , Emily

NSB

catFISH analysis of medial preoptic area neuronal activation during maternal interactions with offspring of varying needs 

Lopez Robinson E; Copelas K; Gadekar A, Pereira M

Maternal behavior that is sensitive to the needs of the offspring in everyday interactions is essential for healthy development in mammals. Postpartum depression (PPD) is a serious health problem that has a tragic impact on the mother’s ability to sensitively care for her child, with life-long consequences for both mother and child. Our prior work demonstrated that the medial Preoptic Area (mPOA), a critical node in the circuitry regulating maternal behavior, is required for this critical maternal ability (i.e. maternal sensitivity). The objective of this study was to examine the contribution of mPOA cells to maternal sensitivity. To this aim, we leveraged the well-validated Wistar-Kyoto (WKY) rat model of depression and used cellular compartment analysis of temporal activity by fluorescence in situ hybridization (catFISH) technique to assess overlap between mPOA population of cells during maternal interactions with offspring with varying needs. WKY and control Sprague-Dawley (SD) mother rats experienced two 10-min interaction episodes, 20 min apart with normal vs increased needs pups. Mothers were perfused immediately after the second episode and their brains processed to quantify nuclear c-fos pre-mRNA and cytoplasmic mRNA transcripts in the mPOA. Consistent with our prior results, WKY mothers exhibited similar caregiving behaviors regardless of offspring needs, highly contrasting the sensitive parenting of SD mothers, indicative of deficits in maternal sensitivity. c-fos catFISH analysis revealed overlapping but distinct neuronal populations involved in adjustments of care that resolve the needs of the offspring. Together, this new work expands our understanding of the mPOA contribution to parenting. 

21: Rodberg, Ellen

NSB, University of Massachusetts Amherst

Locus coeruleus activity differs as a function of species, sex, age, and genetic manipulation

Rodberg E*, Kelberman M*, Arabzadeh E, Bair-Marshall C.J., Berridge C.W., Berrocoso E, Breton-Provencher V, Chandler D.J., Davy O, Devilbiss D.M., Downs A.M., Drummond G, Dvorkin R, Fazlali Z, Froemke R.C., Glennon E, Gold J.I., Ito H, Jiang X, Johansen J.P., Joshi S, Kaye A, Kim J.R., Kuo C.-C., Liu R.-J., Liu Y, Llorca-Torralba M, McCall J.G., McElligott Z.A., McKinney A.M., Miguelez C, Min M.-Y., Nowlan A.C.,Omrani M, Pickering A.E., Poe G.R., Ranjbar-Slamloo Y, Razquin J, Rodenkirch C, Sales A.C., Satyasambit R, Shea S.D., Sur M, Torres-Sanchez S, Uematsu A, Vazquez C.R., Vreven A, Wang Q, Waterhouse B.D., Yang H.-W., Yang J.-H., Zhao L, Zouridis I.S., Weinshenker D, Vazey E, Totah N.K.

Locus coeruleus (LC) neurons are intimately connected with diverse brain functions, most prominently attention, arousal, stress responses, and cognition. Published studies of LC activity cover many traits (species, sex, etc.) but rely on small sample sizes (usually tens of neurons), which has precluded a systematic and robust assessment of how these features affect LC activity. Here, we leverage a pooled dataset of 1,855 single units from 20 laboratories to comprehensively compare LC activity. Verified LC activity was recorded from deafferenated brain slices and intact animals during wakefulness or under different anesthetics. Samples included male non-human primates and rats and mice of both sexes. In some cases, LC activity was recorded from disease models and cell-type selective genetic modifications. We used a negative binomial regression model to identify the individual and combined effects of various attributes on firing rate. This powerful analysis revealed important species-, sex-, age-, and disease model-specific activity, as well as significant effects in Cre-expressing lines. Lastly, in contrast to the foundational concept of two-mode (tonic-phasic) LC activity, we discovered multiple bursting sub-modes and complex second order spike train patterns associated with different LC preparations. In sum, inherent differences in LC activity result from species-, age- and sex-dependent factors, as well as genetic modification. Our findings offer insight into why LC-dependent behavioral and cognitive functions depend on sex and age and may help explain the known association of sex and age with psychiatric disorders.

22: Sebastian, Rebecca

BMB and NSB

Mapping the Functions of schizophrenia-associated NRXN1 in forebrain organoids

Sebastian, Jin, Pavon, Bansal, Potter, Song, Gabriel, Sun, Aronow & Pak. 

Neurexin-1 is a presynaptic cell adhesion molecule that binds to multiple postsynaptic ligands to mediate proper neuronal signaling at the synapse. Notably, large scale human genetic studies have placed the Neurexin-1 gene (NRXN1) as the most frequently deleted single gene mutation for schizophrenia (SCZ). Loss of NRXN1 has been shown to increase susceptibility to the disease by 10-fold. Past studies have shown that the loss of NRXN1, independent of genetic background, resulted in neurotransmission defects in mature human iPSC-derived glutamatergic neurons. Besides that, knockdown of NRXN1 showed a disruption in neuron-glial fate determination. However, up to date, no studies have examined the role of NRXN1 in early brain development. Here we utilized human pluripotent stem cell derived forebrain organoids differentiated from an isogenic line engineered to carry heterozygous loss of NRXN1 (isogenic-NRXN1 del), as well as schizophrenia patients with heterozygous loss of NRXN1 (SCZ-NRXN1 del) to study the functions of NRXN1 during forebrain development. Our single cell transcriptomic data showed most significant perturbations elicited by NRXN1 mutations at a more mature time point (3.5 months), compared to earlier time points (3 weeks and 2 months). However, in a genetic background dependent manner, we observed precocious development of early cell types (such as neuroepithelial cells) and other maturing cell types in the SCZ-NRXN1 del forebrain organoids, but not in the isogenic-NRXN1 del organoids. Moreover, we also observed variable dysregulations in overall spontaneous and synchronous network activity in organoids from both isogenic- and SCZ-NRXN1 del organoids, compared to controls. In contrast, independent of genetic background, the loss of NRXN1 impaired gene regulation related to alternative splicing, and ubiquitin-proteasome activity. Altogether, our findings provide evidence that NRXN1, in addition to having disease and non-disease specific functions, also have convergent functions regardless of genetic background during brain development.

23: Shaila, Shariqa

Neuroscience, Smith College

Investigating the roles of Meteorin and Meteorin-like in early CNS development of zebrafish (Danio rerio)

Shaila S

Within the developing vertebrate central nervous system (CNS), neural progenitor cells give rise to a diverse array of neurons and glial cells. The most prominent progenitor cells, radial glia, are key for cell differentiation and specialization within the CNS. Studies on the differentiation and proliferation of radial glia provide evidence that Meteorin (metrn) may be a novel morphogenic factor for radial glia cells. Meteorin-like (metrnl) is a paralog of metrn. Gain of expression studies through mRNA injections of both metrn and metrnl are indicative that these genes function synergistically. This is evident by changes in phenotypes, such as the production of cyclopia and abnormalities in mid-hindbrain, which are analogous to disruptions in signaling morphogens, such as Sonic hedgehog (Shh) and Nodal. Conversely, morpholino-induced knockdown of metrn alone induced significant reduction in brain size with no cyclopia. Currently, we are trying to characterize metrn and metrnl expression through hybridization chain reaction (HCR) at different time-points of development. We are also attempting to create promoter-less knockouts for metrn and metrnl genes using CRISPR Cas-9 technology to study the effects of the absence of these genes. Furthermore, we are attempting to create a transgenic reporter line using a plasmid constructed in the Tol2 gateway cloning system. This will allow us to track metrn and metrnl expression via intrinsic fluorescence in vivo. Overall, we hypothesize that 1) metrn and metrnl directly function as morphogens or indirectly converge within morphogen signaling pathways, and 2) during normal CNS development, expression of metrn and metrnl genes is a tightly regulated process.

24: Sudana, Korey

Department of Biology, University of Massachusetts Amherst

Refinement and maintenance of receptive field size in V1 neurons of mice occurs despite the absence of visual experience.

Pedro Fernández-Aburto, Korey Sudana, and Sarah L. Pallas.

The role of visual experience in the refinement of visual receptive fields has been studied for years using models with well-developed vision (e.g., carnivores, primates) but more recently in rodents exhibiting less elaborate visual processing circuitry. In nocturnal rodents, such as hamsters and mice, receptive fields refine completely before adulthood. However, hamsters dark reared from birth exhibit a reversion to large receptive fields by adulthood if kept in the dark. We demonstrated previously that in normally reared hamsters, the progressive decrease in receptive field (RF) size of visual neurons in the primary visual cortex (V1) and superior colliculus is achieved before adulthood. Dark reared hamsters also refine their RFs to adult size by adulthood (~60 postnatal days (pnd)), but then exhibit a gradual increase in RF size if kept in the dark after 60 pnd, suggesting a role of visual experience in the maintenance but not in the refinement of the RF sizes. We have now examined whether this difference from carnivores and primates is common to other nocturnal rodents. Abnormally large V1 RF sizes have been reported in dark reared mice around puberty, however, a more detailed study reporting the progression of RF size across different ages is still lacking. We investigated the changes in RF size of single unit V1 neurons (layer 2/3) in anesthetized mice at 30, 60 and 90 pnd. Our preliminary data show progressive refinement of V1 RF sizes between 30 and 60 pnd in normally reared mice (30 pnd: 145 ± 16.8 deg² , n=35; 60 pnd= 116 ± 16.8 deg² , n= 37). Dark-reared mice exhibit a similar trend, showing increasingly refined RFs from P30 to P60 (DR RF areas at 30 pnd: 147 ± 24.1 deg² , n=31; DR RF areas at 60 pnd: 121± 7.6 deg² , n=73). Unlike hamsters, however, dark and normally reared mice retain refined RFs long into adulthood (Normal RF areas at 90 pnd: 96 ± 18.3 deg² n= 15, DR RF areas at 90 pnd: 83 ± 7.8 deg² , n=70). Within each age group, no significant differences were observed between normal and dark-reared individuals. These results suggest that in mice, both refinement and maintenance of RFs in V1 neurons are independent of visual experience. Our study is an important step in developing a better understanding of the role of visual experience in the development of visual processing circuitry in a commonly studied species.

25: White, Hamilton

WPI and UMass Chan Medical School

Microfluidic High-Throughput Methods for the Induction and Characterization of Repeatable, Titratable Traumatic Neural Injury in the Nematode Caenorhabditis elegans

White H., Albrecht, D.

Traumatic brain injury (TBI) causes polymodal trauma leading to persistent changes in brain

function, behavior, cellular structure, and is a known risk factor for neurodegenerative disease. Current injury models correlate the presence and duration of injury conditions with animal behavior, but they do not reveal underlying effects on brain function at the cellular and subcellular scale. To identify underlying mechanisms relating acute brain injury with functional outcomes, we developed a scalable TBI model in nematodes to directly observe injury progression at behavioral, neurofunctional and structural levels. Previously, ultrasonic shock waves and vortex-induced blunt force trauma caused paralysis in thrashing animals, with broad population variability. We investigated ultrasonic cavitation as a repeatable and titratable TBI induction method using computer-controlled bath sonication. Video recordings during sonication revealed animals injured in post-array microfluidic devices were uniformly injured. Repeated assessment of neural function of up to 24 hours allowed examination of neurofunctional recovery. Using this platform, we identified sexually dimorphic outcomes in injury response, a channel inhibitor potentially modulating neural activity recovery, and assayed a model of FHM1 proposed to modulate injury outcome. Overall, sonication-induced TBI provides repeatable assays for real-time, in vivo assessments of injury outcomes, enabling further study on mechanisms, progression, and potential therapies to minimize damage and enhance recovery.

PBS UMass