Parahippocampal gyrus

Parahippocampal gyrus

Infobox Anatomy
Name = PAGENAME
Latin = gyrus parahippocampalis
GraySubject =
GrayPage =


Caption = Medial surface of left cerebral hemisphere. ("Hippocampal gyrus" visible near bottom.)


Caption2 = Parahippocampal gyrus labeled at bottom center.
System =
Precursor =
MeshName = Parahippocampal+Gyrus
MeshNumber = A08.186.211.577.710
DorlandsPre = g_13
DorlandsSuf = 14816442
The parahippocampal gyrus (or hippocampal gyrus) is a grey matter cortical region of the brain that surrounds the hippocampus. This region plays an important role in memory encoding and retrieval. The anterior part of the gyrus includes the perirhinal and entorhinal cortices. The term parahippocampal cortex is used to refer to an area that encompasses both the posterior portion of the parahippocampal gyrus and the medial portion of the fusiform gyrus.

The parahippocampal place area (PPA) is a subregion of the parahippocampal cortex that plays an important role in the encoding and recognition of scenes (rather than faces or objects). 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"). The region was first described by Russell Epstein (currently at the University of Pennsylvania) and Nancy Kanwisher (currently at MIT) in 1998 ( [http://www.nature.com/nature/journal/v392/n6676/abs/392598a0_fs.html] , see also other similar reports by Geoffrey Aguirre [http://www.neuron.org/content/article/abstract?uid=PIIS0896627300805462] and Alumit Ishai [http://www.pnas.org/cgi/content/abstract/96/16/9379?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Ishai&searchid=1&FIRSTINDEX=0&resourcetype=HWCI] ). 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 (FFA), a nearby cortical region that responds strongly whenever faces are viewed, and which is believed to be important for face recognition.

Additional research has increased the probability that the right parahippocampal gyrus in particular has functions beyong the contextualising 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 [ [http://www.nytimes.com/2008/06/03/health/research/03sarc.html?em&ex=1212724800&en=51b0f096761db2f9&ei=5087%0A NY Times] ]


=Additional

References

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* http://www2.umdnj.edu/~neuro/studyaid/Practical2000/Q35.htm
* [http://www.temporal-lobe.com Temporal-lobe.com An interactive diagram of the rat parahippocampal-hippocampal region]


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