Gross anatomy of the squirrel monkey brain. The top panel displays a digital 3D reconstruction of the left hemisphere of a squirrel monkey derived from magnetic resonance imaging. The bottom panel shows post mortem coronal sections (modified from and Gergen and MacLean atlas (Gergen and MacLean, 1962) demonstrating the existence of sulci in the squirrel monkey brain and the close similarity of the subcortical anatomy with humans.