The term area 11 of Walker refers to a subdivision of the frontal lobe of the macaque (Macaca) defined on the basis of cytoarchitecture. The third layer contains small, evenly arranged cells. In the fifth layer there is a "heaping up" of medium-sized pyramidal cells. The fourth layer, internal granular layer, is well-defined, an observation which Walker cites as contrary to the description of cortex in the corresponding location in the guenon (Cercopithecus; Brodmann-1905). Walker regarded the most likely cytoarchitecural homologue in the human to be area 11 of Brodmann (human) ( Walker-1940 ).