The fusiform gyrus, also known as the ''lateral occipitotemporal gyrus'',
'' ''is part of the
temporal lobe
The temporal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe ...
and
occipital lobe
The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head".
The occipital lobe is the vi ...
in
Brodmann area 37
Brodmann area 37, or BA37, is part of the temporal cortex in the human brain. It contains the fusiform gyrus which in turn contains the fusiform face area, an area important for the recognition of faces.
This area is also known as occipitotempor ...
. The
fusiform
Fusiform means having a spindle-like shape that is wide in the middle and tapers at both ends. It is similar to the lemon-shape, but often implies a focal broadening of a structure that continues from one or both ends, such as an aneurysm on a b ...
gyrus
In neuroanatomy, a gyrus (pl. gyri) is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci (depressions or furrows; sg. ''sulcus''). Gyri and sulci create the folded appearance of the brain in humans and other ma ...
is located between the
lingual gyrus
The lingual gyrus, also known as the ''medial'' occipitotemporal gyrus, is a brain structure that is linked to processing vision, especially related to letters. It is thought to also play a role in analysis of logical conditions (i.e., logical ord ...
and
parahippocampal gyrus
The parahippocampal gyrus (or hippocampal gyrus') is a grey matter cortical region of the brain that surrounds the hippocampus and is part of the limbic system. The region plays an important role in memory encoding and retrieval. It has been in ...
above, and the
inferior temporal gyrus
The inferior temporal gyrus is one of three gyri of the temporal lobe and is located below the middle temporal gyrus, connected behind with the inferior occipital gyrus; it also extends around the infero-lateral border on to the inferior surface ...
below. Though the functionality of the fusiform gyrus is not fully understood, it has been linked with various
neural pathways
In neuroanatomy, a neural pathway is the connection formed by axons that project from neurons to make synapses onto neurons in another location, to enable neurotransmission (the sending of a signal from one region of the nervous system to an ...
related to recognition. Additionally, it has been linked to various neurological phenomena such as
synesthesia
Synesthesia (American English) or synaesthesia (British English) is a perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway. People who re ...
,
dyslexia
Dyslexia, also known until the 1960s as word blindness, is a disorder characterized by reading below the expected level for one's age. Different people are affected to different degrees. Problems may include difficulties in spelling words, r ...
, and
prosopagnosia
Prosopagnosia (from Greek ''prósōpon'', meaning "face", and ''agnōsía'', meaning "non-knowledge"), also called face blindness, ("illChoisser had even begun tpopularizea name for the condition: face blindness.") is a cognitive disorder of fac ...
.
Anatomy
Anatomically, the fusiform gyrus is the largest macro-anatomical structure within the
ventral temporal cortex, which mainly includes structures involved in
high-level vision.
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
Emil Huschke (December 14, 1797 – June 19, 1858) was a German anatomist and embryologist who was a native of Weimar.
He studied medicine at the University of Jena, and spent most of his professional career at Jena. In 1827 he was appointe ...
in 1854.
[ (see also section on ]history
History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the History of writing#Inventions of writing, invention of writing systems is considered prehistory. "History" is an umbr ...
).
The fusiform gyrus is situated at the basal surface of the temporal and occipital lobes and is
delineated by the collateral sulcus
The collateral fissure (or sulcus) is on the tentorial surface of the hemisphere and extends from near the occipital pole to within a short distance of the temporal pole.
Behind, it lies below and lateral to the calcarine fissure, from which it ...
(CoS) and occipitotemporal sulcus (OTS), respectively. The OTS separates the fusiform gyrus from the inferior temporal gyrus
The inferior temporal gyrus is one of three gyri of the temporal lobe and is located below the middle temporal gyrus, connected behind with the inferior occipital gyrus; it also extends around the infero-lateral border on to the inferior surface ...
(located laterally in respect to the fusiform gyrus) and the CoS separates the fusiform gyrus from the parahippocampal gyrus
The parahippocampal gyrus (or hippocampal gyrus') is a grey matter cortical region of the brain that surrounds the hippocampus and is part of the limbic system. The region plays an important role in memory encoding and retrieval. It has been in ...
(located medially in respect to the fusiform gyrus).
The fusiform gyrus can be further delineated into a lateral and medial portion, as it is separated in its middle by the relatively shallow mid-fusiform sulcus
The mid-fusiform sulcus is a shallow sulcus that divides the fusiform gyrus into lateral and medial partitions. Functionally, the MFS divides both large-scale functional maps and identifies fine-scale functional regions such as the anterior portion ...
(MFS). 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 fusiform face area
The fusiform face area (FFA, meaning spindle-shaped face area) is a part of the human visual system (while also activated in people blind from birth) that is specialized for facial recognition. It is located in the inferior temporal cortex ( ...
(FFA), a functional subregion of the fusiform gyrus assumed to play a key role in processing faces.
History
The fusiform gyrus has a contentious history that has recently been clarified. The term was first used in 1854 by Emil Huschke
Emil Huschke (December 14, 1797 – June 19, 1858) was a German anatomist and embryologist who was a native of Weimar.
He studied medicine at the University of Jena, and spent most of his professional career at Jena. In 1827 he was appointe ...
from Jena, Germany
Jena () is a German city and the second largest city in Thuringia. Together with the nearby cities of Erfurt and Weimar, it forms the central metropolitan area of Thuringia with approximately 500,000 inhabitants, while the city itself has a popu ...
, 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.
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
Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its siste ...
. This is supported by research showing only three temporal gyri and no fusiform gyrus in macaques.
The first accurate definition of the mid-fusiform sulcus was coined by Gustav Retzius
Prof Magnus Gustaf (or Gustav) Retzius FRSFor HFRSE MSA (17 October 1842 – 21 July 1919) was a Swedish physician and anatomist who dedicated a large part of his life to researching the histology of the sense organs and nervous system.
Li ...
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".
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, V. S. Ramachandran
Vilayanur Subramanian Ramachandran (born 10 August 1951) is an Indian-American neuroscientist. He is known for his wide-ranging experiments and theories in behavioral neurology, including the invention of the mirror box. Ramachandran is a disti ...
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 angular gyrus
The angular gyrus is a region of the brain lying mainly in the posteroinferior region of the parietal lobe, occupying the posterior part of the inferior parietal lobule. It represents the Brodmann area 39.
Its significance is in transferring vis ...
. The angular gyrus is involved in higher processing of colors. 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. 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.
Face and body recognition
Portions of the fusiform gyrus are critical for face and body recognition.
Word recognition
It is believed that portions of the left hemisphere fusiform gyrus are used in word recognition.
Within-category identification
Further research by MIT
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the m ...
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.
Related neural transmitter system
In a 2015 study, dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...
was proposed to play a key role in face recognition
A facial recognition system is a technology capable of matching a human face from a digital image or a video frame against a database of faces. Such a system is typically employed to authenticate users through ID verification services, and wo ...
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. 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.
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.
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 prosopagnosia
Prosopagnosia (from Greek ''prósōpon'', meaning "face", and ''agnōsía'', meaning "non-knowledge"), also called face blindness, ("illChoisser had even begun tpopularizea name for the condition: face blindness.") is a cognitive disorder of fac ...
, or face blindness. Research has also shown that the fusiform face area, the area within the fusiform gyrus, is heavily involved in face perception
Facial perception is an individual's understanding and interpretation of the face. Here, perception implies the presence of consciousness and hence excludes automated facial recognition systems. Although facial recognition is found in other spec ...
but only to any generic within-category identification that is shown to be one of the functions of the fusiform gyrus. Abnormalities of the fusiform gyrus have also been linked to Williams syndrome
Williams syndrome (WS) is a genetic disorder that affects many parts of the body. Facial features frequently include a broad forehead, underdeveloped chin, short nose, and full cheeks. Mild to moderate intellectual disability is observed in people ...
. Fusiform gyrus has also been involved in the perception of emotions in facial stimuli.[
] However, individuals with autism
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
show little to no activation in the fusiform gyrus in response to seeing a human face.
Synaesthesia
Recent research has seen activation of the fusiform gyrus during subjective grapheme–color perception in people with synaesthesia. 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 visual cortex
The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...
associated with experiencing color.
Dyslexia
For those with dyslexia, it has been seen that the fusiform gyrus is underactivated and has reduced gray matter density.
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
Visual release hallucinations, also known as Charles Bonnet syndrome or CBS, are a type of psychophysical visual disturbance in which a person with partial or severe blindness experiences visual hallucinations.
First described by Charles Bonnet in ...
, hypnagogic hallucinations
Hypnagogia is the experience of the transitional state from wakefulness to sleep: the ''hypnagogic'' state of consciousness, during the onset of sleep. Its opposite state is described as the transitional state from sleep into wakefulness. Mental ...
, peduncular hallucinations, or drug-induced hallucinations.[Jan Dirk Blom. ''A Dictionary of Hallucinations''. Springer, 2010, p. 187. ]
Additional images
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
References
External links
* – "Cerebral Hemisphere, Inferior View"
Location
at mattababy.org
*
*
NIF Search – Fusiform Gyrus
via the Neuroscience Information Framework
The Neuroscience Information Framework is a repository of global neuroscience web resources, including experimental, clinical, and translational neuroscience databases, knowledge bases, atlases, and genetic/ genomic resources and provides many aut ...
{{Authority control
Gyri
Temporal lobe
Occipital lobe