Abstract
It has revealed that neurons in the caudal part of intraparietal sulcus (caudal intraparietal, CIP) selectivity respond to 3D axis and surface orientation, suggesting that this region might be important for processing of visual information of 3D structure. To elucidate the importance of CIP in 3D vision further, we investigated response of CIP neurons to more integrated structure–3D curvature. A set of 3D curvatures, such as ellipsoids, cylinders and saddles, was presented to a monkey performing fixation task. Single unit activity was recorded from CIP of the animal during the task. Some CIP neurons showed significant response to one of curvatures. We defined these neurons as curvature selective neurons (CSN). Notably, some CSN were highly selective to a particular shape. The preferred shapes of CSN were biased toward convex and concave ellipsoid, whereas they were distributed over all shapes tested. These results suggest that 3D curvature might be represented in CIP as well as axis and surface orientation. We also investigated architectonic structure of CIP using immunohistochemical staining with SMI-32 antibody. We observed a thick immunoreactive band of SMI-32 in layer 3 and 5 of the lateral bank of intraparietal sulcus (IPS) near the fundus, and found that most of recording sites of CSN fell in that region. These results suggest that CIP might be an architectonically distinct visual area in IPS and might be functionally specialized for 3D vision. [J Physiol Sci. 2007;57 Suppl:S47]
