Patrick Shoemaker
Tanner Research Laboratories
Pasadena, CA

Modeling Adaptation in Insect Visual Motion Processing

It has been known since the early 1980s that adaptation occurs in the neural pathways that detect and process visual motion in insects. Until recently, it was believed that this adaptation was due to adjustment of the time constant of the delay that is an essential feature of the correlational elementary motion detector (EMD), the putative ``front-end'' for all higher-level motion processing. However, convincing evidence has been developed by David O'Carroll of Adelaide University and coworkers that this is not the case and, furthermore, that the primary mechanismn of adaptation is adjustment of contrast gain early in the motion processing pathway. This has interesting implications for the processing performed by EMDs and subsequent motion-sensitive neurons. I describe a collaborative effort with Dr. O'Carroll to model the adaptive EMD in biology and in the medium of analog integrated circuitry.