Periarchicortex is one of two subtypes of
periallocortex
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 (whic ...
,
the other being
peripaleocortex Peripaleocortex is one of two subtypes of periallocortex, the other being periarchicortex. Peripaleocortex is formed at borders between isocortex (neocortex) and paleocortex (a subtype of allocortex). It shows slow histological transition from the ...
.
It is formed at borders between
archicortex
The archicortex, or archipallium, is the phylogenetically oldest region of the brain's cerebral cortex. It is often considered contiguous with the olfactory cortex, but its extent varies among species. In older species, such as fish, the archipa ...
(a subtype of
allocortex
The allocortex or heterogenetic cortex, and neocortex are the two types of cerebral cortex in the brain. The allocortex is the much smaller area of cortex taking up just 10 %, the neocortex takes up the remaining 90 %. It is characterized by havi ...
) and
isocortex
The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, s ...
and shows slow
histological
Histology,
also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...
transition from the four-layered structure typical for archicortex to the six-layered structure typical for isocortex.
Cortical areas that are generally considered to belong to periarchicortex, include
presubiculum,
parasubiculum,
entorhinal cortex
The entorhinal cortex (EC) is an area of the brain's allocortex, located in the medial temporal lobe, whose functions include being a widespread network hub for memory, navigation, and the perception of time.Integrating time from experience in ...
,
perirhinal cortex
The perirhinal cortex is a cortical region in the medial temporal lobe that is made up of Brodmann areas 35 and 36. It receives highly processed sensory information from all sensory regions, and is generally accepted to be an important region ...
,
retrosplenial cortex, periarchicortical part of
cingulate cortex
The cingulate cortex is a part of the brain situated in the medial aspect of the cerebral cortex. The cingulate cortex includes the entire cingulate gyrus, which lies immediately above the corpus callosum, and the continuation of this in the ...
, posterior part of
subcallosal area, and
subgenual area.
Periarchicortex does not contact immediately at borders with the true isocortex and does not transit directly into it. Instead, another transitional area from the isocortex side, called
proisocortex Proisocortex or pro-isocortex is one of two subtypes of cortical areas in the areas belonging to the neocortex. The other subtype is termed the true isocortex. Proisocortical areas are transitional areas placed between areas of true isocortex and a ...
, is formed at such borders.
So, at borders between "true" archicortex and true isocortex, there are two transitional areas. One such area, which is anatomically located closer to the archicortex side and histologically more resembling it, is called periarchicortex.
Another transitional area, which is anatomically located closer to the true isocortex and histologically more resembling it, is called proisocortex.
References
{{neuroanatomy-stub
Cerebral cortex