Periallocortex is one of three subtypes of allocortex, the other two subtypes being paleocortex and archicortex. The periallocortex is formed at transition areas where any of the other two subtypes of allocortex borders with the neocortex (which is also called isocortex).[1]
No one allocortex or even periallocortex area borders, contacts or transitions immediately to the so-called true isocortex. Instead, they border and slowly transition to another transitional area from the neocortex side, called proisocortex, which then slowly transitions to the true isocortex. Thus, at borders between isocortex and allocortex there are two transitional areas, one from allocortex side and histologically more resembling allocortex, so it is called periallocortex, and another from isocortex side, histologically more resembling true isocortex, so it is called proisocortex.[4]
Those two transitional areas (one from isocortex or neocortex side, called proisocortex, and another from allocortex side, called periallocortex) together form what is called mesocortex.[5]
References
^"Periallocortex". BrainInfo. University of Washington. Retrieved 13 October 2017.
^"Peripaleocortex". BrainInfo. University of Washington. Retrieved 13 October 2017.
^"Periarchicortex". BrainInfo. University of Washington. Retrieved 13 October 2017.
^"Proisocortex". BrainInfo. University of Washington. Retrieved 13 October 2017.
^"Mesocortex". BrainInfo. University of Washington. Retrieved 13 October 2017.