# Periallocortex

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Type of cortex between the allocortex and neocortex

Periallocortex Details Part of Allocortex Identifiers Latin Periallocortex NeuroNames 2315 Anatomical terms of neuroanatomy [edit on Wikidata]

**Periallocortex** is one of three subtypes of [allocortex](/source/Allocortex), the other two subtypes being [paleocortex](/source/Paleocortex) and [archicortex](/source/Archicortex). The periallocortex is formed at transition areas where any of the other two subtypes of allocortex borders with the [neocortex](/source/Neocortex) (which is also called isocortex).[1]

Thus, the periallocortex is also subdivided to two subtypes. One subtype is called [peripaleocortex](/source/Peripaleocortex), which is formed at borders between paleocortex and neocortex. Areas considered to belong to peripaleocortex are for example anterior [insular cortex](/source/Insular_cortex).[2] Another subtype of periallocortex is called [periarchicortex](/source/Periarchicortex). It is formed at borders between archicortex and neocortex. Areas considered to belong to periarchicortex include [entorhinal cortex](/source/Entorhinal_cortex), [perirhinal cortex](/source/Perirhinal_cortex), [presubiculum](/source/Presubiculum), [parasubiculum](/source/Parasubiculum), [retrosplenial cortex](/source/Retrosplenial_cortex), [subcallosal area](/source/Subcallosal_area) and [subgenual area](/source/Subgenual_area).[3]

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](/source/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](/source/Mesocortex).[5]

## References

1. **[^](#cite_ref-BrainInfo_Periallocortex_1-0)** ["Periallocortex"](http://braininfo.rprc.washington.edu/CentralDirectory.aspx?ID=2315). *BrainInfo*. University of Washington. Retrieved 13 October 2017.

1. **[^](#cite_ref-BrainInfo_Peripaleocortex_2-0)** ["Peripaleocortex"](http://braininfo.rprc.washington.edu/CentralDirectory.aspx?ID=2337). *BrainInfo*. University of Washington. Retrieved 13 October 2017.

1. **[^](#cite_ref-BrainInfo_Periarchicortex_3-0)** ["Periarchicortex"](http://braininfo.rprc.washington.edu/CentralDirectory.aspx?ID=2302). *BrainInfo*. University of Washington. Retrieved 13 October 2017.

1. **[^](#cite_ref-BrainInfo_Proisocortex_4-0)** ["Proisocortex"](http://braininfo.rprc.washington.edu/CentralDirectory.aspx?ID=2311). *BrainInfo*. University of Washington. Retrieved 13 October 2017.

1. **[^](#cite_ref-BrainInfo_Mesocortex_5-0)** ["Mesocortex"](http://braininfo.rprc.washington.edu/CentralDirectory.aspx?ID=2335). *BrainInfo*. University of Washington. Retrieved 13 October 2017.

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Adapted from the Wikipedia article [Periallocortex](https://en.wikipedia.org/wiki/Periallocortex) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Periallocortex?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.