View source for Biology:Fusiform gyrus

{{short description|Gyrus of the temporal and occipital lobes of the brain}}
{{Infobox brain
| Name            = Fusiform gyrus
| Latin           = gyrus fusiformis
| Image           = Gray727 fusiform gyrus.png
| Caption         = Medial surface of left cerebral hemisphere. (Fusiform gyrus shown in orange)
| Image2          = Medial surface of cerebral cortex - fusiform gyrus.png
| Caption2        = Medial surface of right cerebral hemisphere. (Fusiform gyrus visible near bottom
| IsPartOf        =
| Components      =
| Artery          =
| Vein            =
}}
The '''fusiform gyrus''', also known as the ''lateral occipitotemporal gyrus'',<ref>{{cite book |last1=Rajakumar |first1=Raj |last2=Kiernan |first2=John |title=BARR's The Human Nervous System |year=2014 |isbn=978-1-4511-7327-7 |page=219 |edition=10}}</ref><ref name=":1" />'' ''is part of the [[Biology:Temporal lobe|temporal lobe]] and [[Biology:Occipital lobe|occipital lobe]] in [[Biology:Brodmann area 37|Brodmann area 37]].<ref>Nature Neuroscience, vol7, 2004</ref> The fusiform [[Biology:Gyrus|gyrus]] is located between the [[Biology:Lingual gyrus|lingual gyrus]] and [[Biology:Parahippocampal gyrus|parahippocampal gyrus]] above, and the [[Biology:Inferior temporal gyrus|inferior temporal gyrus]] below.<ref>{{cite web | url=http://medical-dictionary.thefreedictionary.com/fusiform+gyrus | title=Gyrus | publisher=The free dictionary | access-date=2013-06-19}}</ref> Though the functionality of the fusiform gyrus is not fully understood, it has been linked with various neural pathways related to recognition. Additionally, it has been linked to various neurological phenomena such as [[Philosophy:Synesthesia|synesthesia]], [[Medicine:Dyslexia|dyslexia]], and [[Medicine:Prosopagnosia|prosopagnosia]].

==Anatomy==
Anatomically, the fusiform gyrus is the largest macro-anatomical structure within the [[Biology:Two-streams hypothesis#Ventral stream|ventral temporal cortex]], which mainly includes structures involved in [[Biology:Cognitive neuroscience of visual object recognition|high-level vision]].<ref name="Weiner2014">{{cite journal|last1=Grill-Spector|first1=Kalanit|last2=Weiner|first2=Kevin S.|year=2014|title=The functional architecture of the ventral temporal cortex and its role in categorization|journal=Nature Reviews Neuroscience|volume=15|issue=8|pages=536–548|doi=10.1038/nrn3747|pmc=4143420|pmid=24962370}}</ref><ref name=Weiner2015>{{cite journal | last1 = Zilles | first1= Weiner | year = 2015 | title = The anatomical and functional specialization of the fusiform gyrus | journal = Neuropsychologia | volume= 83 | pages= 48–62 |  doi = 10.1016/j.neuropsychologia.2015.06.033| pmid= 26119921 | pmc = 4714959}}</ref> 
The term fusiform gyrus (lit. "spindle-shaped convolution") refers to the fact that the shape of the gyrus is wider at its centre than at its ends. This term is based on the description of the gyrus by Emil Huschke in 1854.<ref name=Weiner2015/> (see also section on [[Biology:Fusiform gyrus#History|history]]). 
The fusiform gyrus is situated at the basal surface of the temporal and occipital lobes and is
delineated by the collateral sulcus (CoS) and occipitotemporal sulcus (OTS), respectively.<ref name=":1">{{cite web|url=http://www.medbookfree.com/grays-anatomy-the-anatomical-basis-of-clinical-practice-41st-edition-2016-pdf/|title=Gray's Anatomy – The Anatomical Basis of Clinical Practice 41st edition|date=26 September 2015|access-date=18 November 2015}}</ref> The OTS separates the fusiform gyrus from the [[Biology:Inferior temporal gyrus|inferior temporal gyrus]] (located laterally in respect to the fusiform gyrus) and the CoS separates the fusiform gyrus from the [[Biology:Parahippocampal gyrus|parahippocampal gyrus]] (located medially in respect to the fusiform gyrus).

{{Gallery
|title=Inferior views of the fusiform gyrus
|width=250
|height=250
|align=center
|File:Fusiform Gyrus on 3D-printed brain, inferior view.png|alt1=The Fusiform gyrus and all gyri adjacent to it, displayed on a 3D-printed brain of a healthy adult. As we view the brain from below, the right hemisphere is on the left side of the image|'''Fusiform gyrus and adjacent gyri.''' {{font color|crimson|fusiform gyrus}}; {{font color|limegreen|inferior temporal gyrus}}; {{font color|midnightblue|parahippocampal gyrus}}; {{font color|darkgoldenrod|lingual gyrus}}; {{font color|darkturquoise|inferior occipital gyrus}}.
|File:Fusiform Gyrus and its Sulci on 3D-printed brain, inferior view.png|alt2=The Fusiform gyrus with all major sulci delimiting it, displayed on a 3D-printed brain of a healthy adult. As we view the brain from below, the right hemisphere is on the left side of the image|'''Fusiform gyrus and delimiting sulci.''' {{font color|crimson|fusiform gyrus}}; {{font color|darkgoldenrod|occipitotemporal sulcus (OTS)}}; {{font color|limegreen|collateral sulcus (CoS)}}; {{font color|midnightblue|mid-fusiform sulcus (MFS)}}.
}}

The fusiform gyrus can be further delineated into a lateral and medial portion, as it is separated in its middle by the relatively shallow [[Biology:Mid-fusiform sulcus|mid-fusiform sulcus]] (MFS).<ref>{{cite journal | first1 = Weiner | last1 = Grill-Spector | display-authors = etal   | year = 2013 | title = The mid-fusiform sulcus: A landmark identifying both cyotarchitectonic and functional divisions of human ventral temporal cortex | journal = NeuroImage | volume = 84| pages = 453–465| doi = 10.1016/j.neuroimage.2013.08.068 | pmid=24021838 | pmc=3962787}}</ref><ref name = Nasr2011 >{{cite journal | last1 = Nasr | year = 2011 | title = Scene-selective cortical regions in human and nonhuman primates | journal = J Neurosci | volume = 31 | issue = 39| pages = 13771–85 | doi=10.1523/jneurosci.2792-11.2011 | pmid=21957240 | pmc=3489186}}</ref><ref>{{cite journal | first1 = Weiner | last1 = Grill-Spector | date = 2010 | title = Sparsely-distributed organization of face and limb activations in human ventral temporal cortex | journal = NeuroImage | volume = 52 | issue = 4| pages = 1559–73 | doi=10.1016/j.neuroimage.2010.04.262 | pmid=20457261 | pmc=3122128}}</ref> Thus, the lateral fusiform gyrus is delineated by the OTS laterally and the MFS medially. Likewise, the medial fusiform gyrus is delineated by the MFS laterally and the CoS medially.

Importantly, the mid-fusiform sulcus serves as a macroanatomical landmark for the [[Biology:Fusiform face area|fusiform face area]] (FFA), a functional subregion of the fusiform gyrus assumed to play a key role in [[Biology:Fusiform gyrus#Face and body recognition|processing faces]].<ref name=Weiner2014 /><ref>{{cite journal | last1 = Grill-Spector | first1 = Weiner | year = 2012 | title = The improbable simplicity of the fusiform face area | journal = Trends in Cognitive Sciences |  doi = 10.1016/j.tics.2012.03.003 | pmid = 22481071 | volume=16 | issue = 5 | pages=251–254| s2cid = 17376865 }}</ref>

==History==
The fusiform gyrus has a contentious history that has recently been clarified. The term was first used in 1854 by Emil Huschke from Jena, Germany, who called the fusiform gyrus a "Spindelwulst" (lit. spindle bulge). He chose this term because of the similarity that the respective cerebral gyrus bears to the shape of a spindle, or fusil, due to its wider central section.<ref name=Weiner2015 /> 
At first, researchers located the fusiform gyrus in other mammals as well, without taking into account the variations in gross organizations of other species' brains. Today, the fusiform gyrus is considered to be specific to hominoids. This is supported by research showing only three temporal gyri and no fusiform gyrus in macaques.<ref name = Nasr2011 />

The first accurate definition of the mid-fusiform sulcus was coined by Gustav Retzius in 1896. He was the first to describe the sulcus sagittalis gyri fusiformis (today: mid-fusiform sulcus), and correctly determined that a sulcus divides the fusiform gyrus into lateral and
medial partitions. W. Julius Mickle mentioned the mid-fusiform sulcus in 1897 and attempted to
clarify the relation between temporal sulci and the fusiform gyrus, calling it the
"intra-gyral sulcus of the fusiform lobule".<ref name=Weiner2015 />

==Function==
The exact functionality of the fusiform gyrus is still disputed, but there is relative consensus on its involvement in the following pathways:

===Processing of color information===
In 2003, [[Biography:V. S. Ramachandran|V. S. Ramachandran]] collaborated with scientists from the Salk Institute for Biological Studies in order to identify the potential role of the fusiform gyrus within the color processing pathway in the brain. Examining the relationship within the pathway specifically in cases of synesthesia, Ramachandran found that synesthetes on average have a higher density of fibers surrounding the [[Biology:Angular gyrus|angular gyrus]]. The angular gyrus is involved in higher processing of colors.<ref name="Tell Tale Brain">{{cite book|last=Ramachandran|first=V.S.|url=https://archive.org/details/telltalebrainneu0000rama|title=The Tell Tale Brain|date=January 17, 2011|publisher=W. W. Norton & Company, Inc.|isbn=978-0-393-34062-4|location=New York|url-access=registration}}<!--|access-date= March 13, 2015--></ref> The fibers relay shape information from the fusiform gyrus to the angular gyrus in order to produce the association of colors and shapes in grapheme-color synesthesia.<ref name="Tell Tale Brain" /> Cross-activation between the angular and fusiform gyri has been observed in the average brain, implying that the fusiform gyrus regularly communicates with the visual pathway.<ref name="pmid16269367">{{cite journal |author=Hubbard EM, Ramachandran VS |title=Neurocognitive mechanisms of synesthesia |journal=Neuron |volume=48 |issue=3 |pages=509–20 |date=November 2005 |pmid= 16269367 |doi=10.1016/j.neuron.2005.10.012 |type= Review|doi-access=free }}</ref>

===Face and body recognition===
{{Further|Biology:Fusiform face area}}
Portions of the fusiform gyrus are critical for face and body recognition.

===Word recognition===
{{Further|Biology:Visual word form area}}
It is believed that portions of the left hemisphere fusiform gyrus are used in word recognition.

===Within-category identification===

Further research by MIT scientists showed that the left and right fusiform gyri played different roles, which subsequently interlinked. The left fusiform gyrus recognizes "face-like" features in objects that may or may not be actual faces, whereas the right fusiform gyrus determines if that recognized face-like feature is, in fact, a face.<ref>[http://web.mit.edu/newsoffice/2011/face-perception-0109.html Trafton, A. "How does our brain know what is a face and what's not?" MIT News]</ref>

== Related neural transmitter system ==
In a 2015 study, [[Biology:Dopamine|dopamine]] was proposed to play a key role in [[Facial recognition system|face recognition]] task and was considered to be related to neural activity in fusiform gyrus. By studying the correlation between the binding potential (BP) of dopamine D1 receptor by PET and blood-oxygen-level-dependent (BOLD) in fMRI scan during a face recognition task, higher availability of D1 receptor was shown to be associated with higher BOLD level. This study showed that this association with D1 BP is only significant for FFG, not other brain regions. The researchers also showed the possibility that higher availability of dopamine D1 receptor may underlie better performance in face recognition task.<ref name=":0">{{Cite journal|last1=Rypma|first1=Bart|last2=Fischer|first2=Håkan|last3=Rieckmann|first3=Anna|last4=Hubbard|first4=Nicholas A.|last5=Nyberg|first5=Lars|last6=Bäckman|first6=Lars|date=2015-11-04|title=Dopamine D1 Binding Potential Predicts Fusiform BOLD Activity during Face-Recognition Performance|journal=The Journal of Neuroscience|volume=35|issue=44|pages=14702–14707|doi=10.1523/JNEUROSCI.1298-15.2015|issn=1529-2401|pmc=4635124|pmid=26538642}}</ref> Dopamine is known to be related to the reward system. The dopaminergic system shows an active response to stimuli that predict possible rewards. As a social demand, a face recognition task could be a cognition process that involves dopamine, which can elicit a reinforcement feedback.<ref name=":0" /><ref>{{Cite journal|last=Schultz|first=Wolfram|date=2007-05-01|title=Behavioral dopamine signals|journal=Trends in Neurosciences|language=en|volume=30|issue=5|pages=203–210|doi=10.1016/j.tins.2007.03.007|issn=0166-2236|pmid= 17400301|s2cid=11965742}}</ref>

A 2007 study investigated how dopamine may regulate FFG activity during a face recognition task. It indicated that BOLD activity can be modulated by dopamine's influence on postsynaptic D1 receptors. The regulation is achieved in a way that dopamine first influence post-synaptic potential, and then further cause BOLD activity increase in the local area. This link between post-synaptic BOLD activity increase and dopamine release can be explained by blockage of dopamine reuptake.<ref>{{Cite journal|last1=Knutson|first1=Brian|last2=Gibbs|first2=Sasha E. B.|date=2007-02-06|title=Linking nucleus accumbens dopamine and blood oxygenation|journal=Psychopharmacology|language=en|volume=191|issue=3|pages=813–822|doi=10.1007/s00213-006-0686-7|issn=0033-3158|pmid=17279377|s2cid=2614688}}</ref>

==Associated neurological phenomena==
The fusiform gyrus has been speculated to be associated with various neurological phenomena.

===Prosopagnosia===
Some researchers think that the fusiform gyrus may be related to the disorder known as [[Medicine:Prosopagnosia|prosopagnosia]], or face blindness. Research has also shown that the fusiform face area, the area within the fusiform gyrus, is heavily involved in [[Face perception|face perception]] but only to any generic within-category identification that is shown to be one of the functions of the fusiform gyrus.<ref>{{cite journal | last1 = McCarthy | first1 = G |display-authors=0 | year = 1997 | title = Face-specific processing in the fuman fusform gyrus | journal = Journal of Cognitive Neuroscience | volume = 9 | issue = 5| pages = 605–610 | doi=10.1162/jocn.1997.9.5.605| pmid = 23965119 | hdl = 2022/22741 | s2cid = 23333049 | hdl-access = free }}</ref> Abnormalities of the fusiform gyrus have also been linked to [[Unsolved:Williams syndrome|Williams syndrome]].<ref>A. L. Reiss, et al. Preliminary Evidence Of Abnormal White Matter Related To The Fusiform Gyrus In Williams Syndrome: A Diffusion Tensor Imaging Tractography Study.''Genes, Brain & Behavior 11.1, 62–68(2012)''</ref> Fusiform gyrus has also been involved in the perception of emotions in facial stimuli.<ref name="radua2010">{{Cite journal
| last1           = Radua | first1 = Joaquim
| last2           = Phillips | first2 = Mary L.
| last3           = Russell | first3 = Tamara
| last4           = Lawrence | first4 = Natalia
| last5           = Marshall | first5 = Nicolette
| last6           = Kalidindi | first6 = Sridevi
| last7           = El-Hage | first7 = Wissam
| last8           = McDonald | first8 = Colm
| last9           = Giampietro | first9 = Vincent
| title           = Neural response to specific components of fearful faces in healthy and schizophrenic adults
| journal         = NeuroImage
| volume          = 49
| issue           = 1
| pages           = 939–946
| year            = 2010
| pmid            = 19699306
| doi             = 10.1016/j.neuroimage.2009.08.030 | s2cid = 6209163
| url=https://zenodo.org/record/1066228
 }}
</ref>  However, individuals with [[Medicine:Autism|autism]] show little to no activation in the fusiform gyrus in response to seeing a human face.<ref>{{cite book|last=Carter|first=Rita|title=The Human Brain Book|pages=241}}</ref>

===Synaesthesia===
Recent research has seen activation of the fusiform gyrus during subjective grapheme–color perception in people with synaesthesia.<ref>[http://neurophilosophy.wordpress.com/2007/05/29/imaging-of-connectivity-in-the-synaesthetic-brain/ Imaging of connectivity in the synaesthetic brain ]</ref> The effect of the fusiform gyrus in grapheme sense seems somewhat more clear as the fusiform gyrus seems to play a key role in word recognition. The connection to color may be due to cross wiring of (being directly connected to) areas of the fusiform gyrus and other areas of the [[Biology:Visual cortex|visual cortex]] associated with experiencing color.<ref name="Pujol">{{Cite journal|last=Pujol|first=J.|date=2009-04-30|title=Study data from J. Pujol and colleagues update understanding of life sciences|url=http://go.galegroup.com/ps/i.do?id=GALE%7CA202892461&v=2.1&it=r&p=AONE&sw=w&asid=e3cc7811e5eaf10537956f5e1f76bdcb|journal=Science Letter}}</ref>

===Dyslexia===
For those with dyslexia, it has been seen that the fusiform gyrus is underactivated and has reduced gray matter density.<ref>{{Cite book|title = The Brain and Behavior|last = Clark|first = David|publisher = Cambridge University Press|year = 2005|isbn = 978-0-521-54984-4}}</ref>

===Face hallucinations===
Increased neurophysiological activity in the fusiform face area may produce hallucinations of faces, whether realistic or cartoonesque, as seen in Charles Bonnet syndrome, [[Biology:Hypnagogia|hypnagogic hallucinations]], [[Medicine:Peduncular hallucinosis|peduncular hallucinations]], or drug-induced hallucinations.<ref>Jan Dirk Blom. ''A Dictionary of Hallucinations''. Springer, 2010, p. 187. {{ISBN|978-1-4419-1222-0}}</ref>

==Additional images==
<gallery>

File:Slide10ee.JPG|Fusiform gyrus
File:Fusiform_gyrus_animation.gif|Fusiform gyrus animation
File:Slide2PIT.JPG|Cerebrum.Inferior view. Deep dissection
File:Sobo 1909 629.png|Fusiform gyrus in a ventral view (from below, diagrammatic), labeled at left
File:Sobo 1909 630.png|Fusiform gyrus seen in a ventral view
File:Fusiform_-_DK_ATLAS_05.png|Fusiform gyrus, in the right cerebral hemisphere.
File:Fusiform gyrus.gif|3D view of the fusiform gyrus. Yellow: temporal section, red: occipito-temporal section, green: occipital section
</gallery>

==References==
{{Reflist}}

==External links==
* {{UMichAtlas|n1a2p13}} – "Cerebral Hemisphere, Inferior View"
* [http://www.mattababy.org/~belmonte/Talks/63_Girelli_slice_location.gif Location] at mattababy.org
* {{TED talk|vilayanur_ramachandran_on_your_mind| 3 clues to understanding your brain |Vilayanur Ramachandran}}
* {{TED talk|oliver_sacks_what_hallucination_reveals_about_our_minds|What hallucination reveals about our minds|Oliver Sacks}}
* [https://www.neuinfo.org/mynif/search.php?q=Fusiform%20Gyrus&t=data&s=cover&b=0&r=20 NIF Search – Fusiform Gyrus] via the [[Biology:Neuroscience Information Framework|Neuroscience Information Framework]]


[[Category:Gyri]]
[[Category:Temporal lobe]]
[[Category:Occipital lobe]]

{{Sourceattribution|Fusiform gyrus}}