“Optic flow circuits and the visual guidance of avian flight”
Douglas L. Altshuler, Ph.D.
Professor, Department of Zoology, University of British Columbia
Abstract: As an animal moves through the world, surfaces and edges in the environment appear to move along the retina, a visual signal known as optic flow. All vertebrates have a rapid pathway for optic flow encoding. From the retina, ganglion cell axons project to two regions in the midbrain, the lentiformis mesencephali and the nucleus of the basal optic root, which respond only to optic flow signals. In mammals, these regions are called the nucleus of the optic tract and the terminal nuclei, respectively. The optic flow information is transmitted to several pre-motor regions in the hindbrain including the inferior olive, the vestibulocerebellum, and the oculomotor cerebellum. The circuit has a well-known role in stabilizing eye movements, and has been thought be highly conserved in its anatomy, neural response properties, and visually-mediated behavior. My collaborators and I have found evidence that this optic flow pathway has a much larger role, also controlling stabilization of the whole body, and the inverse function, maneuverability in response to salient visual signals. I will present evidence that the anatomy of this midbrain optic flow circuit, its neural response properties, and visual guidance strategies are all tuned to differences in species visual ecology and mode of locomotion.
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