Lack of selectivity for simple shapes defined by motion and luminance in STPa of the behaving macaque

The anterior superior temporal polysensory area (STPa) has been hypothesized to be an integration site for signals coming from the dorsal and ventral visual pathways. To determine whether neurons in STPa were selective for simple two-dimensional geometrical shapes and whether this area might integrate different visual cues, cells were tested with motion- and luminance-defined shapes. Many neurons were activated by the shape stimuli under at least one condition; however, very few showed selectivity for a particular shape under either condition. Only one neuron responded selectively to shapes defined by both cues. Thus selectivity for simple shapes is not a prevalent property of STPa neurons and the integration of luminance and motion signals does not appear to occur at the single neuron level in STPa.