Connectivity-Based Parcellation of the Human Inferior Parietal Cortex - New Insights into the Problem of Structure-Function Relationships in Humans and Macaques
Ruschel, M., Anwander, A., Knösche, T. R., Turner, R., Geyer, S.
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig
Introduction: The human inferior parietal cortex (IPC) is a hotly debated region. Cytoarchitectonic parcellations of this functionally complex region range from two up to seven areas and homologies between IPC areas in humans and macaques are unclear.
Methods: We used connectivity-based cortex parcellation. Regions of interest (ROIs) were defined between the intraparietal sulcus, the postcentral sulcus, the lateral fissure and the angular gyrus. Probabilistic tractography was performed followed by clustering of the data. An average tractogram was computed for each region to analyze the connectivity.
Results: Within each ROI in the left and right IPC, we found three regions of comparable size in a rostro-caudal arrangement.
Conclusions: Converging evidence from cytoarchitecture, tract tracing, and electrophysiology support a subdivision of the macaque anterior IPC into a rostro-caudal sequence of three regions. This similarity in the IPC structural organization between macaques and humans suggests substantial conservatism in IPC evolution.