Movement Detection Properties and Structure of Stationary Receptive Fields of Single Neurons in the Cat Extrastriate Area 21a

Response patterns of single neurons in the extrastriate area 21a of the cat cortex to moving visual stimuli were studied, along with juxtaposition to the structure of their stationary receptive fields. First, the precise mapping of stationary RFs was performed by flashing bright spots; then, moving visual stimuli of different shapes and sizes with two opposite contrasts were presented. We found that the majority of investigated neurons with a homogenous stationary RF organization demonstrate significant differences in their activity profiles depending on the size, shape, and contrast of the applied moving visual stimulus. The data obtained support a model in which the RF stationary structure undergoes specific dynamic changes due to simultaneous activation of the RF surround by the moving visual image; this provides more accurate incorporation of moving image information in movement detection.