High-Resolution Cortical Imaging

Structure of the cortex The adult cerebral cortex is a complex convoluted multilayered structure averaging around 2.3mm thick, but thinner (≤ 2mm) in the depths of the sulcal folds and thicker (3-4mm) at the crown of the gyri. It is typically divided into 6 layers depending upon the constituent cell types. On examination a section of the cortex, it is seen to consist of alternating white and gray layers from the surface inward: (1) a thin layer of white substance; (2) a layer of gray substance; (3) a second white layer (outer band of Baillarger or band of Gennari); (4) a second gray layer; (5) a third white layer (inner band of Baillarger); (6) a third gray layer, which rests on the medullary substance of the gyrus (1). Cortical neurons form a highly organized laminar and radial structure with extensive efferents. Long association fibers connect to distant regions of the ipsilateral hemisphere, while short fibers connect to nearby ipsilateral regions. Commissural fibers connect to the cortical regions of the contralateral hemisphere, and projection fibers reach from the cortex into the subcortical structures e.g., corticothalamic/subthalamic projections, etc.