THE SPEED TUNING OF MEDIAL SUPERIOR TEMPORAL (MST) CELL RESPONSES TO OPTIC-FLOW COMPONENTS

The responses of macaque medial superior temporal (MST) cells to trans lation and to the optic-flow components-rotation, expansion/contractio n, and deformation-were examined with particular regard to the speed t uning of MST cells for optic-flow stimuli and the effect of removing s peed gradients from those stimuli. The use of position invariance as a n indispensable criterion for assessing the authenticity of responses to optic flow is reviewed. By extending the scope of testing to includ e higher speeds it is found, in contrast to in previous reports, that MST cells generally respond to optic-flow components with a speed-resp onse profile which is tuned for a particular range of speeds. Removal of the speed gradient had little effect on this observation. These and other properties of MST cells lead to the conclusion that one of the major functions of MST is the detection and encoding of self-motion.