Relative motion sensitivity in cat striate cortex as a function of stimulus direction

Abstract

This paper presents the second stage of an investigation into the relative motion sensitivity of complex cells in the striate cortex of lightly anaesthetized adult cats. Relative motion between an oriented bar and a background of random visual texture was generated by moving both stimuli, in-phase or in antiphase, with dissimilar speed. Three configurations were compared: motion of both foreground bar and background texture in preferred directions for either (a) the bar or (b) the background, and also (c) where background motion was other than orthogonal to bar orientation. Providing foreground stimuli elicited substantial responses, sensitivity to relative motion was qualitatively but not quantitatively predictable from discrete responses to foreground or background alone, whatever the angular inclination between their respective directions, suggestive of strongly non-linear interactions between the two. Where the foreground evoked no response, or depressed firing, the pattern of sensitivity to relative motion could not be predicted.