Brodmann area 23 is a subdivision of the cerebral cortex of the guenon defined on the basis of cytoarchitecture. Brodmann regarded it as topographically and cytoarchitecturally homologous to the combined ventral posterior cingulate area 23 and dorsal posterior cingulate Brodmann area 31 of the human (Brodmann-1909). Distinctive Features (Brodmann-1905): the cortex is relatively thin; smaller cells predominate; the cell density of the multiform layer (VI) is great, producing a distinct boundary with the subcortical white matter; the internal granular layer (IV) is rather well developed; the internal pyramidal layer (V) contains a dense population of round, medium-sized ganglion cells concentrated at the border with layer IV; layers V and VI are narrow with a distinct mutual boundary.
Macaque
In the macaque the researchers Bonin and Bailey describe an area they term LC which is in agreement with Brodmann area 23. The LC area
covers the posterior part of the cingulate gyrus and extends into the cingulate sulcus where, on the inferior wall, it is continuous with the frontal cortex FDL.[1]
Subdivisions
The area has been subdivided further: In the macaque (Macaca fascicularis) the following subdivisions have been suggested:[2]
23i (internal)
23e (external)
23v (ventral), the most caudalventral (inferior) portion and with most highly developed layer IV.
