Paralimbic cortex

The paralimbic cortex 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.[1][2]

Paralimbic cortex
Piriform cortex from a 14-day-old mouse, stained for D2-eGFP (green), enkephalin (red) and DAPI (blue) to show nuclei. Epifluorescence.
Details
Identifiers
Latin	Cortex paralimbicus
Anatomical terms of neuroanatomy

The paralimbic cortex lies close to, and is directly connected with, the structures of the limbic system.[1] (The prefix para meaning beside or adjacent to.) The paralimbic cortex, also referred to as the mesocortex, or juxtallocortex, is interposed between the neocortex and the allocortex.[3] The paralimbic cortex provides a gradual transition from primary limbic regions, including the septal region, substantia innominata, and the amygdala nuclei, to higher neocortical regions.[4]

There are dense connections between the paralimbic cortex 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.[5] 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 (less than six layers) and the neocortex (six distinct layers). It is found within the limbic system, representing the border between neocortical and allocortical parts.[6][7] It has been hypothesized that the cortex should be viewed as concentric rings of allocortex, mesocortex (paralimbic cortex), and isocortex (neocortex).[8]