| Parahippocampal gyrus | |
|---|---|
 Human brain seen from below. Parahippocampal gyrus shown in blue | |
 Medial view of leftcerebral hemisphere. Parahippocampal gyrus shown in orange. | |
| Details | |
| Identifiers | |
| Latin | gyrus parahippocampalis |
| MeSH | D020534 |
| NeuroNames | 164 |
| NeuroLex ID | birnlex_807 |
| TA98 | A14.1.09.234 |
| TA2 | 5515 |
| FMA | 61918 |
| Anatomical terminology | |
Theparahippocampal gyrus (orhippocampal gyrus[1]) is agrey mattercortical region, agyrus of thebrain that surrounds thehippocampus and is part of thelimbic system. The region plays an important role inmemoryencoding andretrieval. It has been involved in some cases ofhippocampal sclerosis.[2] Asymmetry has been observed inschizophrenia.[3]
The anterior part of the gyrus includes theperirhinal andentorhinal cortices[citation needed].
The termparahippocampal cortex is used to refer to an area that encompasses both theposterior parahippocampal gyrus and the medial portion of thefusiform gyrus[citation needed].
Theparahippocampal 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 andrecognition of environmental scenes (rather than faces).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 byPierre Mégevand et al. in 2014, stimulation of the region via intracranial electrodes yields intense topographical visual hallucinations of places and situations.[4] The region was first described byRussell Epstein andNancy Kanwisher in 1998 at MIT,[5] see also other similar reports byGeoffrey Aguirre[6][7] andAlumit Ishai.[8]
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 thefusiform face area (FFA), a nearby cortical region that responds strongly whenever faces are viewed, and that is believed to be important for face recognition.
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.[9] For example, Rankin's research suggests that the right parahippocampal gyrus enables people to detect sarcasm.
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