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angular gyrus: Definition and Much More from Answers.com

  • ️Wed Jul 01 2015
Brain: Angular gyrus

Surfacegyri.jpg

Figure one illustrates significant language areas of the brain. Brodmann area 39 is highlighted in red.

Gray1197.png

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
Dorlands/Elsevier g_13/12405109

The angular gyrus is a region of the brain that is part of the limbic system 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 and cognition. It is Brodmann area 39 of the human brain.

Function

Use in language

Geschwind proposes 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 left angular gyrus and whose speaking and comprehending English was 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.

In another exercise, the patients all failed to be able to describe a bulbous object as "booba" and a jagged object as "kiki," whereas more than 90% of unaffected subjects succeeded in the test. 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.

Out-of-body experiences

Recent experiments have demonstrated the possibility that stimulation of the angular gyrus is the cause of out-of-body experiences. [1] Stimulation of the angular gyrus in one experiment caused a woman to perceive a phantom existence behind her.[2] Another such experiment gave the test subject the feeling 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. This phenomenon is similar to phantom limb syndrome.

Additional images

Lateral surface of left cerebral hemisphere, viewed from above.

Lateral surface of left cerebral hemisphere, viewed from the side.

References

    External links

    Brain: telencephalon (cerebrum, cerebral cortex, cerebral hemispheres)
    Primary sulci/fissures Medial longitudinal, Lateral, Central, Parietoöccipital, Calcarine, Cingulate, Callosal Collateral fissure
    Frontal lobe Precentral gyrus (Primary motor cortex, 4), Precentral sulcus, Superior frontal gyrus/Frontal eye fields (6, 8, 9), Middle frontal gyrus (46), Inferior frontal gyrus (44-Pars opercularis, 45-Pars triangularis), Orbitofrontal cortex (10, 11, 12, 47)
    Parietal lobe Somatosensory cortex (Primary (1, 2, 3, 43), Secondary (5)), Precuneus (7m), Parietal lobules (Superior (7l), Inferior (40)), Angular gyrus (39), Intraparietal sulcus, Marginal sulcus
    Occipital lobe Primary visual cortex (17), Cuneus, Lingual gyrus, 18, 19 - Lateral occipital sulcus
    Temporal lobe Primary auditory cortex (41, 42), Superior temporal gyrus (38, 22), Middle temporal gyrus (21), Inferior temporal gyrus (20), Fusiform gyrus (37) Medial temporal lobe (Amygdala, Hippocampus, Parahippocampal gyrus (27, 28, 34, 35, 36)
    Cingulate cortex/gyrus Subgenual area (25), anterior cingulate (24, 32, 33), Posterior cingulate (23, 31), Retrosplenial cortex (26, 29, 30), Supracallosal gyrus
    white matter tracts Corpus callosum (Splenium, Genu, Rostrum, Tapetum), Septum pellucidum, Ependyma, Internal capsule, Corona radiata, External capsule, Olfactory tract, Fornix (Commissure of fornix), Anterior commissure, Posterior commissure Terminal stria
    Basal ganglia Striatum (Putamen,Caudate nucleus, Nucleus accumbens), Globus pallidus, Claustrum, Subthalamic nucleus, Substantia nigra
    Other Insular cortex Olfactory bulb, Anterior olfactory nucleus Septal nuclei Basal optic nucleus of Meynert
    Some categorizations are approximations, and some Brodmann areas span gyri.

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