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PARIETAL LOBE
The parietal lobe is a lobe in the brain. It is positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe.
Anatomy
The central sulcus separates the parietal lobe from the frontal lobe, and the parieto-occipital sulcus separates the parietal and occipital lobe.
The parietal lobe can be subdivided into the superior parietal lobule and the inferior parietal lobule with the two separated by the intraparietal sulcus.
The parietal operculum forms the superior wall of sylvian fissure.
It includes Brodmann areas 3, 5, 7, 39 and 40.
Function
The parietal lobe plays important roles in integrating sensory information from various parts of the body, and in the manipulation of objects. Portions of the parietal lobe are involved with visuospatial processing. Much less is known about this lobe than the other three in the cerebrum.
Various studies in the 1990s found that different regions of the parietal cortex in Macaques represent different parts of space.
- The lateral intraparietal (LIP) contains a 2-dimensional topographic map of retinotopically-coded space representing the saliency of spatial locations. It can be used by the oculomotor system for targeting eye movements, when appropriate.
- The ventral intraparietal (VIP) area contains a map of space within roughly 5cm of the mouth.
- The medial intraparietal (MIP) area maps space within range of the Macaque's reach. Interestingly, this map changes if the monkey is given a tool to increase its reach.
- The anterior intraparietal (AIP) helps map object location and shape into grasping coordinates.
Pathology
Gerstmann's syndrome is associated with lesion to the dominant (usually left) parietal lobe. Balint's syndrome is associated with bilateral lesions. The syndrome of hemispatial neglect is usually associated with large lesions of the non-dominant hemisphere.
| Telencephalon (cerebrum, cerebral cortex, cerebral hemispheres) - edit |
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primary sulci/fissures: medial longitudinal, lateral, central, parietoöccipital, calcarine, cingulate
frontal lobe: precentral gyrus (primary motor cortex, 4), precentral sulcus, superior frontal gyrus (6, 8), middle frontal gyrus (46), inferior frontal gyrus (Broca's area, 44-pars opercularis, 45-pars triangularis), prefrontal cortex (orbitofrontal cortex, 9, 10, 11, 12, 47)
parietal lobe: postcentral sulcus, postcentral gyrus (1, 2, 3, 43), superior parietal lobule (5), inferior parietal lobule (39-angular gyrus, 40), precuneus (7), intraparietal sulcus
occipital lobe: primary visual cortex (17), cuneus, lingual gyrus, 18, 19 (18 and 19 span whole lobe)
temporal lobe: transverse temporal gyrus (41-42-primary auditory cortex), superior temporal gyrus (38, 22-Wernicke's area), middle temporal gyrus (21), inferior temporal gyrus (20), fusiform gyrus (36, 37)
limbic lobe/fornicate gyrus: cingulate cortex/cingulate gyrus, anterior cingulate (24, 32, 33), posterior cingulate (23, 31),
isthmus (26, 29, 30), parahippocampal gyrus (piriform cortex, 25, 27, 35), entorhinal cortex (28, 34)
subcortical/insular cortex: rhinencephalon, olfactory bulb, corpus callosum, lateral ventricles, septum pellucidum, ependyma, internal capsule, corona radiata, external capsule
hippocampal formation: dentate gyrus, hippocampus, subiculum
basal ganglia: striatum (caudate nucleus, putamen), lentiform nucleus (putamen, globus pallidus), claustrum, extreme capsule, amygdala, nucleus accumbens
Some categorizations are approximations, and some Brodmann areas span gyri.
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