Seminar | March 19 | 12-1 p.m. | 489 Minor Hall
Dr. David Berson, Professor of Medical Science, Chair of NeuroScience, Brown University
Abstract: Self-motion triggers complementary visual and vestibular reflexes supporting image-stabilization and balance. Translation through space produces one global pattern of retinal image motion (optic flow), rotation another. We show that each subtype of direction-selective ganglion cell (DSGC) adjusts its direction preference topographically to align with specific translatory optic flow fields, creating a neural ensemble tuned for a specific direction of motion through space. Four cardinal translatory directions are represented, aligned with two axes of high adaptive relevance: the body and gravitational axes. One subtype maximizes its output when the mouse advances, others when it retreats, rises, or falls. ON-DSGCs and ON-OFF-DSGCs share the same spatial geometry but weight the four channels differently. Each subtype ensemble is also tuned for rotation. The relative activation of DSGC channels uniquely encodes every translation and rotation. Though retinal and vestibular systems both encode translatory and rotatory self-motion, their coordinate systems differ.