CSRC Colloquium
Models for Propagating Facilitation in the Insect Visual System
Friday, March 13, 2020
3:00 PM
Dr. Patrick Shoemaker, Research Associate Professor, Computational Science Research Center, SDSU
Insects that chase prey or mates on the wing do so under visual guidance. Small target motion-detecting (STMD) neurons found in the visual pathways of several flying insects display remarkable selectivity and sensitivity to small moving targets, and are thought to support these behaviors. Contributing to their sensitivity is a form of facilitation, in which the responsiveness of an STMD is enhanced by prior exposure to a small target moving along a continuous path in visual space. The locus of facilitation in the receptive field is found to be local to the area of the target, and to continue propagating in the direction of target motion even after a stimulus ceases. We are modeling this phenomenon with the propagation of traveling waves in densely interconnected, retinotopic layers of cells. We hypothesize that waves are initiated and reinforced by presence of a moving target stimulus, and the network in turn interacts with STMDs to modulate their excitability. Membrane potentials travel too fast to play this role, so we are studying calcium waves as one possible mechanism. In addition, electrical signals that are delayed by frequent synapses (interconnections) with slow kinetics are under consideration.

Jose Castillo