Cross references: Vertebrates Anamniotes Amniote Fish Teleosts
Teleost Hormones Teleost Serotonin Teleost Cortisol Teleost Muscles
Teleost Dominance Hierarchies Neuroethology Anurian Prey Catching
Initiation of Locomotion in Lampreys Predatory Behavior
An adult female zebrafish
zebrafish (Danio rerio) is a tropical freshwater fish belonging to the minnow family (Cyprinidae) of the order Cypriniformes. Native to the Himalayan region, it is a popular aquarium fish, frequently sold under the trade name zebra danio. The zebrafish is also an important vertebrate model organism in scientific research. It is particularly notable for its regenerative abilities, and has been modified by researchers to produce several transgenic strains.
Brain neurons which project to the spinal cord in young larvae of the zebrafish
"A small number of brain neurons project to caudal levels of the spinal cord in the larva of the teleost Brachydanio rerio. These cells were identified in animals 6 days after fertilization by backfilling with horseradish peroxidase following transection of the cord at the level of the cloaca. In preparations with the most labeled cells a total of 30-40 were present on each side of the midline. They were located within three regions of the brainstem: the midbrain nucleus of origin of the medial longitudinal fascicle (mlf), the hindbrain reticular formation, and the hindbrain vestibular nucleus. A total of 15 classes of cells could be distinguished by soma positions, dendritic fields, and axonal pathways. For some of these classes only one or two cells were usually present on each side of the brain. Most of the labeled cells contributed axons to the mlf ipsilateral to the soma; however, the Mauthner cells and three new types of hindbrain reticulospinal reticulospinal cells have decussating axons that enter the contralateral mlf. The observed distribution of labeled reticulospinal cells is similar to that previously described for large reticular cells in adult teleosts and to the system of identified Mauthner and Müller cells in the lamprey."
187 Related citations:
and 22 Cited by's.
Visual prey capture in larval zebrafish is controlled by identified reticulospinal neurons downstream of the tectum.
from the Abstract:
"Seven-day-old zebrafish oriented toward, chased, and consumed paramecia with high accuracy. Lesions of the retinotectal neuropil primarily abolished orienting movements toward the prey."
"To trace the pathway further, we examined the role of two pairs of identified reticulospinal neurons, MeLc and MeLr, located in the nucleus of the medial longitudinal fasciculus of the tegmentum. These two neurons extend dendrites into the ipsilateral tectum and project axons into the spinal cord."
"These results suggest that MeLc and MeLr function in series with the tectum, as part of a circuit that coordinates prey capture movements."
My comments on the Abstract of "Visual prey capture ...," above:
1. I need to look at the full text.
2. The sub-reference, below, was labeled a "Comment In" to this article. The sub-reference did not have an Abstract but was available as a Full Free Text.
Appetite for Destruction: Neuron Ablations, Prey Capture, and Sensorimotor Integration in Larval Zebrafish
from the Free Full Text of the Sub-reference:
"Neuroethology has developed as a branch of neuroscience with the explicit goal of linking neural activities to behavior."
"Although much is known about the morphological aspects of sensory and motor systems in zebrafish, we are just beginning to learn about sensorimotor integration, i.e., how sensory signals are translated into neuronal responses (Niell and Smith, 2005) and then into motor commands that direct behaviors."
"In their recent Journal of Neuroscience article, Gahtan et al. (2005) (http://www.jneurosci.org/cgi/content/full/25/40/9294) present research that has uncovered a putative small neural circuit that is responsible for visually mediated prey-capture behaviors in larval zebrafish."
"The authors have provided strong evidence for a neural pathway involved in visually mediated prey capture. The MeL neurons represent a point at which visual information is transmitted to the motor system to generate an appropriate response to the stimuli."
I need to look into "neuroethology" as described above.
3<132from the Abstract:
A dedicated visual pathway for prey detection in larval zebrafish
http://www.ncbi.nlm.nih.gov/pubmed/25490154 - Free Full Text -
"Two-photon calcium imaging revealed a small visual area, AF7, that was activated specifically by the optimal prey stimulus. This pretectal region is innervated by two types of retinal ganglion cells, which also send collaterals to the optic tectum. Laser ablation of AF7 markedly reduced prey capture behavior. We identified neurons with arbors in AF7 and found that they projected to multiple sensory and premotor areas: the optic tectum, the nucleus of the medial longitudinal fasciculus (nMLF) and the hindbrain. These findings indicate that computations in the retina give rise to a visual stream which transforms sensory information into a directed prey capture response."
My comment:As a first order approximation I'm going to assume that the "hindbrain" referred to, above, includes:
Visuomotor transformations underlying hunting behavior in zebrafish.
from the Abstract:
"In summary, the optic tectum contains non-linear mixed selectivity neurons that are likely to mediate reliable detection of ethologically relevant sensory stimuli. Recruitment of small tectal assemblies appears to link perception to action by providing the premotor commands that release hunting responses. These findings allow us to propose a model circuit for the visuomotor transformations underlying a natural behavior. "
I'm assuming that the "hunting responses" released by the "premotor commands" are mediated by the: