Understanding location- and feature-based processing along the human intraparietal sulcus.

Based on different cognitive tasks and mapping methods, the human intraparietal sulcus (IPS) has been subdivided according to multiple different organizational schemes. The presence of topographically organized regions throughout IPS indicates a strong location-based processing in this brain region. However, visual short-term memory (VSTM) studies have shown that while a region in the inferior IPS region (inferior IPS) is involved in object individuation and selection based on location, a region in the superior IPS (superior IPS) primarily encodes and stores object featural information. Here, we determined the localization of these two VSTM IPS regions with respect to the topographic IPS regions in individual participants and the role of different IPS regions in location- and feature-based processing. Anatomically, inferior IPS showed an 85.2% overlap with topographic IPS regions, with the greatest overlap seen in V3A and V3B, and superior IPS showed a 73.6% overall overlap, with the greatest overlap seen in IPS0-2. Functionally, there appeared to be a partial overlap between IPS regions involved in location- and feature-based processing, with more inferior and medial regions showing a stronger location-based processing and more superior and lateral regions showing a stronger feature-based processing. Together, these results suggest that understanding the multiplex nature of IPS in visual cognition may not be reduced to examining the functions of the different IPS topographic regions, but rather, it can only be accomplished by understanding how regions identified by different tasks and methods may colocalize with each other.