Caudal Intraparietal Sulcus and three-dimensional vision: A combined functional magnetic resonance imaging and single-cell study

摘要

The cortical network processing three-dimensional (3D) object structure defined by binocular disparity spans boththe ventral and dorsal visual streams. However, very little is known about the neural representation of 3Dstructure at intermediate levels of the visual hierarchy. Here, we investigated the neural selectivity for 3D surfacesin the macaque Posterior Intraparietal area (PIP) in the medial bank of the caudal intraparietal sulcus (IPS). Wefirst identified a region sensitive to depth-structure information in the medial bank of the caudal IPS usingfunctional Magnetic Resonance Imaging (fMRI), and then recorded single-cell activity within this fMRI activationin the same animals. Most PIP neurons were selective for the 3D orientation of planar surfaces (first-orderdisparity) at very short latencies, whereas a very small fraction of PIP neurons were selective for curved surfaces(second-order disparity). A linear support vector machine classifier could reliably identify the direction of thedisparity gradient in planar and curved surfaces based on the responses of a population of disparity-selective PIPneurons. These results provide the first detailed account of the neuronal properties in area PIP, which occupies anintermediate position in the hierarchy of visual areas involved in processing depth structure from disparity.