The term Brodmann area 12 refers to a subdivision of the cerebral cortex of the guenon defined on the basis of cytoarchitecture. It occupies the most rostral portion of the frontal lobe. Brodmann-1909 did not regard it as homologous, either topographically or cytoarchitecturally, to rostral area 12 of the human. Distinctive features (Brodmann-1905): a quite distinct internal granular layer (IV) separates slender pyramidal cells of the external pyramidal layer (III) and the internal pyramidal layer (V); the multiform layer (VI) is expanded, contains widely dispersed spindle cells and merges gradually with the underlying cortical white matter; all cells, including the pyramidal cells of the external and internal pyramidal layers are inordinately small; the internal pyramidal layer (V) also contains spindle cells in groups of two to five located close to its border with the internal granular layer (IV).
Brodmannarea 20, or BA20, is part of the temporal cortex in the human brain.
Cytoarchitecturally it is bounded medially by the ectorhinal area 36 (H), laterally by the middle temporal area 21, rostrally by the temporopolar area 38 (H) and caudally by the occipitotemporal area 37 (H) (Brodmann-1909).
Brodmannarea 20 is a subdivision of the cerebral cortex of the guenon defined on the basis of cytoarchitecture.