Juxtallocortex

The mésocortex is an area of three-layered cortex that includes the following regions: the piriform cortex, entorhinal cortex, the parahippocampal cortex on the medial surface of the temporal lobe, and the cingulate cortex just above the corpus callosum.

The mésocortex lies close to, and is directly connected with, the structures of the limbic system. The mesocortex, is interposed between the neocortex and the allocortex. The mesocortex provides a gradual transition from primary limbic regions, including the septal region, substantia innominata, and the amygdala nuclei, to higher neocortical regions.

There are dense connections between the mesocortex and core limbic structures, in particular the amygdala. The amygdaloid complex comprises both nuclear and cortical layers. These cortical features of the amygdala often extend into the paralimbic areas, blurring the boundaries between limbic and paralimbic regions. Thus, these regions may collectively be termed the ‘paralimbic system’.

It is cytoarchitecturally defined: it has three layers, where layer 2,3 and 4 are merged, and is intermediate in form between the allocortex and the neocortex. It is found within the limbic system, representing the border between neocortical and allocortical parts. It has been hypothesized that the cortex should be viewed as concentric rings of allocortex, mesocortex and isocortex.