cerebral cortex

cerebral cortex

We follow NIFSTD in defining cerebral cortex and including both neocortex and hippocampal formation (DG+hippocampus).

cortex of cerebral hemisphere

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The cerebral cortex is a structure within the brain that plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It constitutes the outermost layer of the cerebrum. In preserved brains, it has a grey color, hence the name 'grey matter'. Grey matter is formed by neurons and their unmyelinated fibers, whereas the white matter below the grey matter of the cortex is formed predominantly by myelinated axons interconnecting different regions of the central nervous system. The human cerebral cortex is 2-4 mm (0.08-0.16 inches) thick. The surface of the cerebral cortex is folded in large mammals, such that more than two-thirds of the cortical surface is buried in the grooves, called 'sulci. ' The phylogenetically most recent part of the cerebral cortex, the neocortex, also called isocortex, is differentiated into six horizontal layers; the more ancient part of the cerebral cortex, the hippocampus (also called archicortex), has at most three cellular layers, and is divided into subfields. Relative variations in thickness or cell type (among other parameters) allow us to distinguish between different neocortical architectonic fields. The geometry of at least some of these fields seems to be related to the anatomy of the cortical folds, and, for example, layers in the upper part of the cortical ridges seem to be more clearly differentiated than in its deeper parts. [WP,unvetted][Wikipedia:Cerebral_cortex].

uberon

Migration of neurons from the basal or striatal portions of the anterior part of the neural tube occurs to varying degrees in different vertebrate classes, but a true cerebral cortex is generally acknowledged to have made its first appearance in reptiles. The definition can be unambiguous, since 'cortex' simply implies the existence of a surface neuronal layer with an overlying 'zonal lamina' or 'molecular' layer containing dendrites and axons, which is separated from the underlying basal 'matrix' by white matter. Although reptilian cerebral cortex does indeed fulfill these conditions in certain locations, the separation from striatal structures is often indistinct, so that it may even be argued that some primitive dipnoans possess a pallium or cortex. Nevertheless, an extensive laminated layer separated by underlying white matter is well represented only in reptiles and mammals.[well established][VHOG]

UBERON:0000956

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UBERON:0000956

hagfishes have independently evolved a highly laminated cerebral cortex, comparable in many ways to the cerebral cortex of mammals [http://icb.oxfordjournals.org/content/42/4/743]