Brodmann area 13

Brodmann area 13 is a subdivision of the cerebral cortex as defined on the guenon monkey and on the basis of cytoarchitecture. Along with Brodmann area 14 and 15, Brodmann area 13 is found only in primates and no equivalent structure exists in humans.

Location
Located in the posterior of the insular cortex, Brodmann area 13 shares with other parts of the insular cortex a wide molecular layer (I) and very wide multiform layer (VI).

Layers
The external granular layer (II) is relatively dense. The external pyramidal layer (III) has a central stripe of less cellular density that separates two sublayers, IIIa and IIIb. The internal granular layer (IV) is sufficiently wide and dense to separate clearly sublayer IIIb from layer V. The boundary between layers V and VI is defined by larger ganglion cells, more pyramidal in shape, in layer V giving way to smaller, more spindle-shaped cells that become denser and more homogeneous deeper in layer VI. Often the spindle cells are arrayed horizontally as in the claustrum (VICl), which Brodmann considered a likely extension of layer VI beyond the extreme capsule (VICe) (Brodmann-1905).