Theoretical and Experimental Determination of the Robust Biological Mechanism ofDirectional Selectivity

摘要

Physiological experimentation ana electrotonic modeling and simulation of On-Offdirectionally selective ganglion cells of the rabbit retina were interactively conducted to determine (1) the computational algorithms used by these cells to achieve their robust selectivity for direction of motion, (2) the synaptic circuitry which biophysically implements the directional-selective mechanism. The research showed that retinal directional selectivity Was based on both a last facilitative and slower, sustained inhibitory mechanism involving asymmetric contacts from retinal interneurons (amacrine cells). The research showed that this combination of interacting mechanisms could produce robust directionality independent of stimulus contrast sign and amount, speed, and shape. The mechanisms used by these cells perform direction selectivity more precisely and robustly than prior, extant theoretical mechanisms such as Reichardt correlation detectors. As such, artificial mechanisms built to detect direction of motion may fruitfully use the biological mechanisms studied in this research.