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The parahippocampal gyrus (or hippocampal gyrus') is a
grey matter Grey matter (or gray matter) is a major component of the central nervous system The central nervous system (CNS) is the part of the nervous system In biology Biology is the natural science that studies life and living organisms, ...
cortical Cortex or cortical may refer to: Science Anatomy * Cortex (anatomy), the outermost or superficial layer of an organ * Cortex (hair), the middle layer of a strand of hair * Adrenal cortex, the portion of the adrenal gland that produces cortisol and ...
region of the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
that surrounds the
hippocampus The hippocampus (via Latin from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its popul ...

hippocampus
and is part of the
limbic system The limbic system, also known as the paleomammalian cortex, is a set of brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and anim ...
. The region plays an important role in
memory Memory is the faculty of the brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exis ...

memory
encoding In communication Communication (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', mean ...
and retrieval. It has been involved in some cases of hippocampal sclerosis. Asymmetry has been observed in
schizophrenia Schizophrenia is a mental disorder A mental disorder, also called a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may b ...

schizophrenia
.


Structure

The anterior part of the gyrus includes the perirhinal and
entorhinal The entorhinal cortex (EC) is an area of the brain's allocortex, located in the medial temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer ...
cortices. The term parahippocampal cortex is used to refer to an area that encompasses both the posterior parahippocampal gyrus and the medial portion of the
fusiform gyrus The fusiform gyrus, also known as the ''lateral occipitotemporal gyrus'','' ''is part of the temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the o ...

fusiform gyrus
.


Function


Scene recognition

The parahippocampal place area (PPA) is a sub-region of the parahippocampal cortex that lies medially in the inferior temporo-occipital cortex. PPA plays an important role in the encoding and
recognition Recognition may refer to: *Award, something given in recognition of an achievement In science and technology In computer science *Pattern recognition, a branch of machine learning which encompasses the meanings below Biometric *Recognition of h ...
of environmental scenes (rather than faces).
fMRI Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynami ...

fMRI
studies indicate that this region of the brain becomes highly active when human subjects view topographical scene stimuli such as images of landscapes, cityscapes, or rooms (i.e. images of "places"). Furthermore, according to work by Pierre Mégevand et al. in 2014, stimulation of the region via intracranial electrodes yields intense topographical visual hallucinations of places and situations. The region was first described by Russell Epstein and
Nancy Kanwisher Nancy Gail Kanwisher FBA (born 1958) is the Ellen Swallow Richards Professor in the Department of Brain and Cognitive Sciences at the Massachusetts Institute of Technology Massachusetts Institute of Technology (MIT) is a private land-gr ...
in 1998 at MIT, see also other similar reports by Geoffrey Aguirre and Alumit Ishai. Damage to the PPA (for example, due to stroke) often leads to a syndrome in which patients cannot visually recognize scenes even though they can recognize the individual objects in the scenes (such as people, furniture, etc.). The PPA is often considered the complement of the
fusiform face area The fusiform face area (FFA, meaning fusiform, spindle-shaped face area) is a part of the human visual system (while also activated in people blind from birth) that is specialized for face perception, facial recognition. It is located in the Infer ...
(FFA), a nearby cortical region that responds strongly whenever faces are viewed, and that is believed to be important for face recognition.


Social context

Additional research has suggested that the right parahippocampal gyrus in particular has functions beyond the contextualizing of visual background. Tests by a California-based group led by Katherine P. Rankin indicate that the lobe may play a crucial role in identifying social context as well, including paralinguistic elements of verbal communication. For example, Rankin's research suggests that the right parahippocampal gyrus enables people to detect sarcasm.


Additional images

File:Parahippocampal gyrus animation.gif, Animation. Parahippocampal gyrus shown red. File:Gray727 parahippocampal gyrus.png, Medial surface of left cerebral hemisphere. Parahippocampal gyrus shown in orange. File:Human brain inferior-medial view description.JPG, Human brain inferior-medial view. Parahippocampal gyrus labelled as #5 File:Gehirn Frontalschnitt hippocampus.png, Coronal section. Parahippocampal gyrus labelled at bottom center. File:Hippocampus (brain).jpg, Coronal section of
hippocampus The hippocampus (via Latin from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its popul ...

hippocampus
. Parahippocampal gyrus labelled at bottom. File:Gehirn, basal - beschriftet lat.svg, Basal view of a human brain. File:Parahippocampal gyrus.jpg, Basal view of a human brain. Parahippocampal gyrus shown in yellow. File:Slide4MIR.JPG, Close up of parahippocampal gyrus. Parahippocampal - DK ATLAS.png, Parahippocampal gyrus, shown in right cerebral hemisphere. File:Parahippocampal gyrus coronal sections.gif, Parahippocampal gyrus highlighted in green on coronal T1 MRI images File:Parahippocampal gyrus sagittal sections.gif, Parahippocampal gyrus highlighted in green on sagittal T1 MRI images File:Parahippocampal gyrus transversal sections.gif, Parahippocampal gyrus highlighted in green on transversal T1 MRI images


References


External links

* * https://web.archive.org/web/20090505072544/http://www2.umdnj.edu/~neuro/studyaid/Practical2000/Q35.htm
Temporal-lobe.com An interactive diagram of the rat parahippocampal-hippocampal region
{{Authority control Hippocampus (brain) Gyri