Characterising temporal delay filters in biological motion detectors

Abstract

Motion detection requires the comparison of spatially and temporally displaced samples of the image. Here, we discuss the problems associated with measuring the delay between spatially displaced signals within biological motion detectors. Data are presented from direction-selective neurons in the nucleus of the optic tract of the wallaby, Macropus eugenii. Their motion responses depend on stimulus contrast and the adapted state of the cells. At low contrasts or in an adapted state, it appears that the input to the motion detectors is a temporally low-passed version of the image. At high contrasts or in the unadapted state, the input signals appear to be temporally band-pass-filtered. Contrar..