A flattened representation of the neocortical areas of Macaca mulatta as obtained from combined MRI and histology

The macaque cerebral cortex corresponds to a disk of roughly 130 mm diameter and constitutes of possibly over one hundred different areas as described by a wealth of anatomical, electrophysiological and neurochemical studies. Based on the recently published MRI and histology atlas (Saleem and Logothetis, A combined MRI and histology atlas of the rhesus monkey brain in stereotaxic coordinates. London: Academic Press; 2007) we provide a flattened representation of these areas using techniques implemented in the mrVISTA software suite (Wandel et al., J Cogn Neurosci 12, 739-752, 2000). For this we segmented 125 areas of the neocortex on MR sections based on corresponding histological sections of the same monkey. The border between white and grey matter was also marked and used for surface mesh and flat map generation. The segmented areas were then projected onto the flat maps. Our results show that the surface area on these flat maps are in good agreement with previously published data for areas such as V1, V2 and also for the total neocortex. The differences ranging in these cases were between 3 and 6%. The average size of an area was 140 mm^2 and the seven largest areas were V1, V2, V4,1-2, 3a-b, and F1. These results confirms previous work that in the macaques the largest brain regions are devoted to vision, followed by regions devoted to somatosensation and motor control. Figure legend: On the left the flat map of a Macaca mulatta cerebral cortex is shown with the main sulci, and the occipital gyrus (OG) marked. Darker regions of the image correspond to the sulci, while lighter regions correspond to the gyri. On the right we show the flattened map with different neocortical areas