The supramarginal gyrus is a portion of the
parietal lobe
The parietal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integra ...
. This area of the brain is also known as
Brodmann area 40 based on the brain map created by
Korbinian Brodmann to define the structures in the cerebral cortex. It is probably involved with language perception and processing, and lesions in it may cause
receptive aphasia
Wernicke's aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding Written language, written and spoken language. Patients with Wern ...
.
Important functions
The supramarginal gyrus is part of the
somatosensory association cortex, which interprets tactile sensory data and is involved in perception of space and limbs location. It is also involved in identifying postures and gestures of other people and is thus a part of the
mirror neuron system.
The right-hemisphere supramarginal gyrus appears to play a central role in controlling
empathy
Empathy is generally described as the ability to take on another person's perspective, to understand, feel, and possibly share and respond to their experience. There are more (sometimes conflicting) definitions of empathy that include but are ...
towards other people. When this structure is not working properly or when individuals have to make very quick judgements, empathy becomes severely limited. Research has shown that disrupting the neurons in the right supramarginal gyrus causes humans to project emotions on others, inhibiting the ability to be empathetic. In addition, this disruption also causes people to be more egocentric, mainly because they are not able to perceive the emotions of those around them. Both the left and right supramarginal gyri of healthy, right-handed individuals are shown to be active when making phonological word choices. Individuals who had lesions to the left hemisphere had more difficulty than those with lesions to the right hemisphere, reinforcing the dominance of the left hemisphere in language.
Relationships to surrounding structures
The supramarginal gyrus is located just
anterior
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
to 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 ...
allowing these two structures (which comprise the
inferior parietal lobule
The inferior parietal lobule (subparietal district) lies below the horizontal portion of the intraparietal sulcus, and behind the lower part of the postcentral sulcus. Also known as Geschwind's territory after Norman Geschwind, an American neu ...
) to form a multimodal complex that receives somatosensory, visual, and auditory inputs from the brain.
Although the supramarginal gyrus is not considered a major portion of the language circuit, it still works with the angular gyrus to attempt to link words with meanings. It is also bound caudally by the
lateral sulcus
The lateral sulcus (or lateral fissure, also called Sylvian fissure, after Franciscus Sylvius) is the most prominent sulcus (neuroanatomy), sulcus of each cerebral hemisphere in the human brain. The lateral sulcus (neuroanatomy), sulcus is a deep ...
, one of the most prominent structures found in the brain.
Additional images
File:Supramarginal gyrus animation small.gif, Position of supramarginal gyrus (shown in red).
See also
*
Brodmann area 40
References
External links
* http://braininfo.rprc.washington.edu/centraldirectory.aspx?ID=108
*http://thebrain.mcgill.ca/flash/a/a_10/a_10_cr/a_10_cr_lan/a_10_cr_lan.html
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Gyri
Parietal lobe