| Brain: Angular gyrus | ||
|---|---|---|
|
Angular gyrus
|
||
| Drawing of a cast to illustrate the relations of the brain to the skull. (Angular gyrus labeled at upper left, in yellow section.) | ||
| Latin | gyrus angularis | |
| NeuroNames | hier-91 | |
| NeuroLex ID | birnlex_1376 | |
The angular gyrus is a region of the brain in the parietal lobe, that lies near the superior edge of the temporal lobe, and immediately posterior to the supramarginal gyrus; it is involved in a number of processes related to language, mathematics and cognition. It is Brodmann area 39 of the human brain.
Contents |
Geschwind proposed that written word is translated to internal monologue via the angular gyrus.
V. S. Ramachandran, director of the Center for Brain and Cognition at the University of California, San Diego, directed a study that showed that the angular gyrus is at least partially responsible for understanding metaphors. Right-handed patients who had damage to their right angular gyrus, and whose speaking and comprehending English were seemingly unaffected, could not grasp the dual nature of metaphor. Given a common metaphorical phrase, each patient could give only a literal meaning. If pressed, they could invent a wild interpretation but it was well off the mark[1]
In another exercise, the patients did not recognise a bulbous object as "bouba" and a jagged object as "kiki," whereas more than 90% of unaffected subjects did so in the test (See Bouba/kiki effect). This showed an inability to connect visual stimuli to language.
The fact that the angular gyrus is proportionately much larger in hominids than other primates, and its strategic location at the crossroads of areas specialized for processing touch, hearing and vision, leads Ramachandran to believe that it is critical both to conceptual metaphors and to cross-modal abstractions more generally.
Damage to the angular gyrus manifests as Gerstmann syndrome.
Recent experiments have demonstrated the possibility that stimulation of the angular gyrus is the cause of out-of-body experiences. [2] Stimulation of the angular gyrus in one experiment caused a woman to perceive a phantom existence behind her.[3] Another such experiment gave the test subject the sensation of being on the ceiling. This is attributed to a discrepancy in the actual position of the body, and the mind's perceived location of the body.
Since 1919, brain injuries to the angular gyrus have been known to often cause arithmetic deficits.[4][5] Functional imaging has shown that while other parts of the parietal lobe bilaterally are involved in approximate calculations due to its link with spatiovisual abilities, the left angular gyrus together with left Inferior frontal gyrus are involved in exact calculation due to verbal arithmetic fact retrieval[6] and when this is greater, a person's mathematical abilities are also greater.[7]
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||