View source for Piriform cortex

{{Short description|Region of the brain}}
{{Infobox Brain
| Name        = Piriform cortex
| Latin       = cortex piriformis 
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| Image       = Human brainstem anterior view 2 description.JPG
| Caption     = Human brainstem anterior (piriform cortex not labeled, but most of it is visible near #7)
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The '''piriform cortex''', or '''pyriform cortex''', is a region in the [[brain]], part of the [[rhinencephalon]] situated in the [[cerebrum]]. The function of the piriform cortex relates to [[olfaction|the sense of smell]].

==Structure==
The piriform cortex is part of the [[rhinencephalon]] situated in the [[cerebrum]].

In human anatomy, the piriform cortex has been described as consisting of the cortical [[amygdala]], [[uncus]], and anterior [[parahippocampal gyrus]].<ref name="isbn1-4160-3445-5">{{cite book |author1=Estomih Mtui |author2=Gregory Gruener |title=Clinical Neuroanatomy and Neuroscience: With STUDENT CONSULT Online Access |publisher=Saunders |location=Philadelphia |year=2006 |pages=368 |isbn=978-1-4160-3445-2 }}</ref> More specifically, the human piriform cortex is located between the [[insular cortex|insula]] and the [[temporal lobe]], anteriorly and laterally of the amygdala.<ref name = "Howard-2009">Howard, J. D., Plailly, J., Grueschow, M., Haynes, J. D., & Gottfried, J. A. (2009). Odor quality coding and categorization in human posterior piriform cortex. Nature neuroscience, 12(7), 932-938. Supplementary material, p.4</ref><ref>Mai, J. K. & Paxinos, G. (2008). Atlas of the human brain, 3rd edition. San Diego:: Academic Press. Coronal Atlas – Plate 8 (anterior view). online: http://www.thehumanbrain.info/head_brain/hn_horizontal_atlas/horizontal.html</ref>

==Function==
The function of the piriform cortex relates to [[olfaction]], which is the perception of [[odor|smell]]. This has been particularly shown in humans for the posterior piriform cortex.<ref name="Howard-2009" />

The piriform cortex in rodents and some primates has been shown to harbor cells expressing markers of plasticity such as [[doublecortin]] and PSA-NCAM which are modulated by the noradrenergic neurotransmitter system.<ref>{{Cite journal|title=Elsevier: Article Locator|journal=Neuroscience|volume=372|pages=46–57|doi=10.1016/j.neuroscience.2017.12.037|pmid=29289719|year=2018|last1=Fasemore|first1=Thandi M.|last2=Patzke|first2=Nina|last3=Kaswera-Kyamakya|first3=Consolate|last4=Gilissen|first4=Emmanuel|last5=Manger|first5=Paul R.|last6=Ihunwo|first6=Amadi O.}}</ref><ref>{{Cite journal|last=Vadodaria|first=Krishna C.|last2=Yanpallewar|first2=Sudhirkumar U.|last3=Vadhvani|first3=Mayur|last4=Toshniwal|first4=Devyani|last5=Liles|first5=L. Cameron|last6=Rommelfanger|first6=Karen S.|last7=Weinshenker|first7=David|last8=Vaidya|first8=Vidita A.|date=2017-03-22|title=Noradrenergic regulation of plasticity marker expression in the adult rodent piriform cortex|journal=Neuroscience Letters|volume=644|pages=76–82|doi=10.1016/j.neulet.2017.02.060|pmid=28237805|pmc=5526722}}</ref>

==Clinical significance==
The piriform cortex contains a critical, functionally defined [[epileptogenesis|epileptogenic]] trigger zone, "Area Tempestas".<ref>{{cite journal |vauthors=Piredda S, Gale K |title = A crucial epileptogeneic site in the deep prepiriform cortex|journal = Nature|volume = 317|issue = 6038|pages = 623–5|date=October 1985|pmid = 4058572|doi=10.1038/317623a0}}</ref>  From this site in piriform cortex chemical and electrically evoked seizures can be triggered.  It is the site of action for the proconvulsant action of chemoconvulsants.<ref>{{cite journal |vauthors=Löscher W, Ebert U |title=The role of the piriform cortex in kindling |journal=Prog. Neurobiol. |volume=50 |issue=5–6 |pages=427–81 |date=December 1996 |pmid=9015822 |doi=10.1016/s0301-0082(96)00036-6}}</ref>

==Other animals==
[[Image:Piriform cortex of a mouse.jpg|thumb|Piriform cortex from a 14-day-old D2-eGFP (green) mouse stained for [[enkephalin]] (red) and DAPI (blue) to show nuclei. [[Fluorescence microscope|Epifluorescence]].]]
Sometimes called the ''olfactory cortex'', ''olfactory lobe'' or ''paleopallium'', piriform cortical regions are present in the brains of [[amphibians]], [[reptile]]s and [[mammal]]s.

The piriform cortex is among three areas that emerge in the [[telencephalon]] of amphibians, situated [[Caudal (anatomical term)|caudally]] to a dorsal area, which is caudal to a hippocampal area. Further along the [[phylogeny|phylogenic timeline]], the telencephalic bulb of reptiles as viewed in a cross section of the transverse plane extends with the [[archipallium|archipallial]] hippocampus folding toward the midline and down as the dorsal area begins to form a recognizable cortex.

As mammalian brains developed, volume of the dorsal cortex increased in slightly greater proportion, as compared proportionally with increased overall brain volume, until it enveloped the [[hippocampus|hippocampal]] regions. Recognized as [[neopallium]] or [[neocortex]], enlarged dorsal areas envelop the [[paleopallium|paleopallial]] piriform cortex in [[human]]s and [[Old World monkey]]s.

Among [[scientific classification|taxonomic groupings]] of mammals, the piriform cortex and the [[olfactory bulb]] become proportionally smaller in the brains of [[phylogeny|phylogenically]] younger species. The piriform cortex occupies a greater proportion of the overall brain and of the telencephalic brains of [[insectivore]]s than in [[primate]]s. The piriform cortex continues to occupy a consistent albeit small and declining proportion of the increasingly large [[telencephalon]] in the most recent primate species while the volume of the olfactory bulb becomes less in proportion.

==See also==
* [[List of regions in the human brain|Regions in the human brain]]

==References==
{{reflist}}

==External links==
* {{BrainInfo|hier|147}}
* [http://www.newmanveterinary.com/CerebralCortex.html Diagram]
* [http://brainmaps.org/index.php?i=piriform%20cortex High Resolution Images of Piriform Cortex]

{{Olfactory_system}}
{{Prosencephalon}}

[[Category:Cerebral cortex]]
[[Category:Olfactory system]]