Secondary somatosensory cortex

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S2 is colored green and the insular cortex brown in the top right image (coronal section) of the human brain. S1 is green in the top left, and the supplementary somatosensory area is green in the bottom left. Schematic of cortical areas involved with pain processing and fMRI cropped.jpg
S2 is colored green and the insular cortex brown in the top right image (coronal section) of the human brain. S1 is green in the top left, and the supplementary somatosensory area is green in the bottom left.

The human secondary somatosensory cortex (S2, SII) is a region of cortex in the parietal operculum on the ceiling of the lateral sulcus.

Region S2 was first described by Adrian in 1940, who found that feeling in cats' feet was not only represented in the primary somatosensory cortex (S1) but also in a second region adjacent to S1. [1] In 1954, Penfield and Jasper evoked somatosensory sensations in human patients during neurosurgery by electrically stimulating the ceiling of the lateral sulcus, which lies adjacent to S1, and their findings were confirmed in 1979 by Woolsey et al. using evoked potentials and electrical stimulation. [2] [3] Experiments involving ablation of the second somatosensory cortex in primates indicate that this cortical area is involved in remembering the differences between tactile shapes and textures. [4] [5] Functional neuroimaging studies have found S2 activation in response to light touch, pain, visceral sensation, and tactile attention. [6]

In monkeys, apes and hominids, including humans, region S2 is divided into several "areas". An area at the entrance to the lateral sulcus, adjoining the primary somatosensory cortex (S1), is called the parietal ventral (PV) area. Posterior to PV is the secondary somatosensory area (area S2, which must not be confused with "region S2" which designates the entire secondary somatosensory cortex, of which area S2 is a part). Deeper in the lateral sulcus lies the ventral somatosensory (VS) area, whose outer edge adjoins areas PV and S2 and inner edge adjoins the insular cortex.

In humans, the secondary somatosensory cortex includes parts of Brodmann area (BA) 40 and 43. [7]

Areas PV and S2 both map the body surface. Functional neuroimaging in humans has revealed that in areas PV and S2 the face is represented near the entrance to the lateral sulcus, and the hands and feet deeper in the fissure. Individual neurons in areas PV and S2 receive input from wide areas of the body surface (they have large "receptive fields"), and respond readily to stimuli such as wiping a sponge over a large area of skin. [7]

Area PV connects densely with BA 5 and the premotor cortex. Area S2 is interconnected with BA 1 and densely so with BA 3b, and projects to PV, BA 7b, insular cortex, amygdala and hippocampus. Areas S2 in the left and right hemispheres are densely interconnected, and stimulation on one side of the body will activate area S2 in both hemispheres. [7]

See also

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A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells.

<span class="mw-page-title-main">Parietal lobe</span> Part of the brain responsible for sensory input and some language processing

The parietal lobe is one of the four 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.

<span class="mw-page-title-main">Precuneus</span> Region of the parietal lobe of the brain

In neuroanatomy, the precuneus is the portion of the superior parietal lobule on the medial surface of each brain hemisphere. It is located in front of the cuneus. The precuneus is bounded in front by the marginal branch of the cingulate sulcus, at the rear by the parieto-occipital sulcus, and underneath by the subparietal sulcus. It is involved with episodic memory, visuospatial processing, reflections upon self, and aspects of consciousness.

<span class="mw-page-title-main">Brodmann area 10</span>

Brodmann area 10 is the anterior-most portion of the prefrontal cortex in the human brain. BA10 was originally defined broadly in terms of its cytoarchitectonic traits as they were observed in the brains of cadavers, but because modern functional imaging cannot precisely identify these boundaries, the terms anterior prefrontal cortex, rostral prefrontal cortex and frontopolar prefrontal cortex are used to refer to the area in the most anterior part of the frontal cortex that approximately covers BA10—simply to emphasize the fact that BA10 does not include all parts of the prefrontal cortex.

<span class="mw-page-title-main">Brodmann area 44</span> Brain area

Brodmann area 44, or BA44, is part of the frontal cortex in the human brain. Situated just anterior to premotor cortex (BA6) and on the lateral surface, inferior to BA9.

<span class="mw-page-title-main">Brodmann area 5</span> Brain area

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<span class="mw-page-title-main">Brodmann area 40</span> Part of the parietal cortex in the human brain

Brodmann area 40 (BA40) is part of the parietal cortex in the human brain. The inferior part of BA40 is in the area of the supramarginal gyrus, which lies at the posterior end of the lateral fissure, in the inferior lateral part of the parietal lobe.

<span class="mw-page-title-main">Postcentral gyrus</span> Region of the parietal lobe of the brain

In neuroanatomy, the postcentral gyrus is a prominent gyrus in the lateral parietal lobe of the human brain. It is the location of the primary somatosensory cortex, the main sensory receptive area for the sense of touch. Like other sensory areas, there is a map of sensory space in this location, called the sensory homunculus.

<span class="mw-page-title-main">Lateral sulcus</span> Crevice in the brain separating the frontal and parietal lobes from the temporal

In neuroanatomy, the lateral sulcus is one of the most prominent features of the human brain. The lateral sulcus is a deep fissure in each hemisphere that separates the frontal and parietal lobes from the temporal lobe. The insular cortex lies deep within the lateral sulcus.

<span class="mw-page-title-main">Inferior frontal gyrus</span> Part of the brains prefrontal cortex

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<span class="mw-page-title-main">Primary somatosensory cortex</span> Region of the brain which processes touch

In neuroanatomy, the primary somatosensory cortex is located in the postcentral gyrus of the brain's parietal lobe, and is part of the somatosensory system. It was initially defined from surface stimulation studies of Wilder Penfield, and parallel surface potential studies of Bard, Woolsey, and Marshall. Although initially defined to be roughly the same as Brodmann areas 3, 1 and 2, more recent work by Kaas has suggested that for homogeny with other sensory fields only area 3 should be referred to as "primary somatosensory cortex", as it receives the bulk of the thalamocortical projections from the sensory input fields.

<span class="mw-page-title-main">Motor cortex</span> Region of the cerebral cortex

The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus.

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<span class="mw-page-title-main">Supramarginal gyrus</span> Gyrus of the parietal lobe of the brain

The supramarginal gyrus is a portion of the parietal lobe. 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.

<span class="mw-page-title-main">Lobes of the brain</span> Parts of the cerebrum

The lobes of the brain are the major identifiable zones of the cerebral cortex, and they comprise the surface of each hemisphere of the cerebrum. The two hemispheres are roughly symmetrical in structure, and are connected by the corpus callosum. They traditionally have been divided into four lobes, but are today considered as having six lobes each. The lobes are large areas that are anatomically distinguishable, and are also functionally distinct to some degree. Each lobe of the brain has numerous ridges, or gyri, and furrows, the sulci that constitute further subzones of the cortex. The expression "lobes of the brain" usually refers only to those of the cerebrum, not to the distinct areas of the cerebellum.

<span class="mw-page-title-main">Brodmann area 43</span> Brain area

Brodmann area 43, the subcentral area, is a structurally distinct area of the cerebral cortex defined on the basis of cytoarchitecture. Along with Brodmann Area 1, 2, and 3, Brodmann area 43 is a subdivision of the postcentral region of the brain, suggesting a somatosensory function. The histological structure of Area 43 was initially described by Korbinian Brodmann, but it was not labeled on his map of cortical areas.

<span class="mw-page-title-main">Premotor cortex</span>

The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks. Different subregions of the premotor cortex have different properties and presumably emphasize different functions. Nerve signals generated in the premotor cortex cause much more complex patterns of movement than the discrete patterns generated in the primary motor cortex.

The sensory cortex can refer informally to the primary somatosensory cortex, or it can be used as a term for the primary and secondary cortices of the different senses : the visual cortex on the occipital lobes, the auditory cortex on the temporal lobes, the primary olfactory cortex on the uncus of the piriform region of the temporal lobes, the gustatory cortex on the insular lobe, and the primary somatosensory cortex on the anterior parietal lobes. Just posterior to the primary somatosensory cortex lies the somatosensory association cortex, which integrates sensory information from the primary somatosensory cortex to construct an understanding of the object being felt. Inferior to the frontal lobes are found the olfactory bulbs, which receive sensory input from the olfactory nerves and route those signals throughout the brain. Not all olfactory information is routed to the olfactory cortex: some neural fibers are routed to the supraorbital region of the frontal lobe, while others are routed directly to limbic structures. The direct limbic connection makes the olfactory sense unique.

<span class="mw-page-title-main">Somatosensory system</span> Nerve system for sensing touch, temperature, body position, and pain

In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch, as well as temperature (thermoception), body position (proprioception), and pain. It is a subset of the sensory nervous system, which also represents visual, auditory, olfactory, and gustatory stimuli.

<span class="mw-page-title-main">Primary motor cortex</span> Brain region

The primary motor cortex is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region of the motor system and works in association with other motor areas including premotor cortex, the supplementary motor area, posterior parietal cortex, and several subcortical brain regions, to plan and execute voluntary movements. Primary motor cortex is defined anatomically as the region of cortex that contains large neurons known as Betz cells, which, along with other cortical neurons, send long axons down the spinal cord to synapse onto the interneuron circuitry of the spinal cord and also directly onto the alpha motor neurons in the spinal cord which connect to the muscles.

References

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  4. Ridley, R.M. and Ettlinger, G. (1976). "Impaired tactile learning and retention after removals of the second somatic sensory projection cortex (S11) in the monkey". Brain Research. 109 (3): 656–660. doi:10.1016/0006-8993(76)90048-2. PMID   819106. S2CID   34457858.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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