同: 中心後回

WordNet

a convex fold or elevation in the surface of the brain (同)convolution

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/10/16 02:50:48」(JST)

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Postcentral gyrus (animation)

The lateral postcentral gyrus is a prominent structure in the 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.

The primary somatosensory cortex 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.

At the primary somatosensory cortex, tactile representation is orderly arranged (in an inverted fashion) from the toe (at the top of the cerebral hemisphere) to mouth (at the bottom). However, some body parts may be controlled by partially overlapping regions of cortex. Each cerebral hemisphere of the primary somatosensory cortex only contains a tactile representation of the opposite (contralateral) side of the body. The amount of primary somatosensory cortex devoted to a body part is not proportional to the absolute size of the body surface, but, instead, to the relative density of cutaneous tactile receptors on that body part. The density of cutaneous tactile receptors on a body part is generally indicative of the degree of sensitivity of tactile stimulation experienced at said body part. For this reason, the human lip and hands have a larger representation than other body parts.

Structure

The lateral postcentral gyrus is bounded by:

medial longitudinal fissure medially (to the middle)
central sulcus rostrally (in front)
postcentral sulcus caudally (in back)
lateral sulcus inferiorly (underneath)

Brodmann areas 3, 1 and 2

Brodmann areas 3, 1, and 2 make up the primary somatosensory cortex of the human brain (or S1). Because Brodmann sliced the brain somewhat obliquely, he encountered area 1 first; however, from anterior to posterior, the Brodmann designations are 3, 1, and 2, respectively.

Brodmann area (BA) 3 is subdivided into areas 3a and 3b. Where BA 1 occupies the apex of the postcentral gyrus, the rostral border of BA 3a is in the nadir of the Central sulcus, and is caudally followed by BA 3b, then BA 1, with BA 2 following and ending in the nadir of the postcentral sulcus. BA 3b is now conceived as the primary somatosensory cortex because 1) it receives dense inputs from the NP nucleus of the thalamus; 2) its neurons are highly responsive to somatosensory stimuli, but not other stimuli; 3) lesions here impair somatic sensation; and 4) electrical stimulation evokes somatic sensory experience. BA 3a also receives dense input from the thalamus; however, this area is concerned with proprioception.

Areas 1 and 2 receive dense inputs from BA 3b. The projection from 3b to 1 primarily relays texture information; the projection to area 2 emphasizes size and shape. Lesions confined to these areas produce predictable dysfunction in texture, size, and shape discrimination.

Somatosensory cortex, like other neocortex, is layered. Like other sensory cortex (i.e., visual and auditory) the thalamic inputs project into layer IV, which in turn project into other layers. As in other sensory cortices, S1 neurons are grouped together with similar inputs and responses into vertical columns that extend across cortical layers (e.g., As shown by Vernon Mountcastle, into alternating layers of slowly adapting and rapidly adapting neurons; or spatial segmentation of the vibrissae on mouse/rat cerebral cortex).

This area of cortex, as shown by Wilder Penfield and others, is organized somatotopically, having the pattern of a homunculus. That is, the legs and trunk fold over the midline; the arms and hands are along the middle of the area shown here; and the face is near the bottom of the figure. While it is not well-shown here, the lips and hands are enlarged on a proper homunculus, since a larger number of neurons in the cerebral cortex are devoted to processing information from these areas.

The positions of Brodmann areas 3, 1, and 2 are - from the nadir of the central sulcus toward the apex of the postcentral gyrus - 3a, 3b, 1, and 2, respectively.

These areas contain cells that project to the secondary somatosensory cortex.

Clinical significance

Lesions affecting the primary somatosensory cortex produce characteristic symptoms including: agraphesthesia, astereognosia, hemihypesthesia, and loss of vibration, proprioception and fine touch (because the third-order neuron of the medial-lemniscal pathway cannot synapse in the cortex). It can also produce hemineglect, if it affects the non-dominant hemisphere. Destruction of brodmann area 3, 1, and 2 results in contralateral hemihypesthesia and astereognosis.

It could also reduce nociception, thermoception, and crude touch, but, since information from the spinothalamic tract is interpreted mainly by other areas of the brain (see insular cortex and cingulate gyrus), it is not as relevant as the other symptoms^{[citation needed]}.

Additional images

Lateral surface of left cerebral hemisphere, viewed from the side.
Drawing to illustrate the relations of the brain to the skull.
Sensory homunculus of the human brain.
Lateral view of a human brain, main gyri labeled.
Cerebrum. Lateral view.Deep dissection.
Cerebrum. Lateral view.Deep dissection.
Cerebrum. Lateral view.Deep dissection.
Primary cortici, including primary somatosensory cortex (labeled in purple)

External links

ancil-1040 at NeuroNames - area 1
ancil-1041 at NeuroNames - area 2
ancil-1042 at NeuroNames - area 3

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English Journal

Changes in neural mechanisms of cognitive control during the transition from late adolescence to young adulthood.

Veroude K, Jolles J, Croiset G, Krabbendam L.SourceDepartment of Educational Neuroscience, Faculty of Psychology and Education & LEARN! Institute, VU University Amsterdam, The Netherlands. Electronic address: k.veroude@vu.nl.
Developmental cognitive neuroscience.Dev Cogn Neurosci.2013 Jul;5:63-70. doi: 10.1016/j.dcn.2012.12.002. Epub 2013 Jan 11.
The transition from late adolescence to young adulthood is marked by anatomical maturation of various brain regions. In parallel, defining life changes take place, such as entrance into college. Up till now research has not focused on functional brain differences during this particular developmental
PMID 23376475

Somatosensory mechanical response and digit somatotopy within cortical areas of the postcentral gyrus in humans: An MEG study.

Inoue K, Nakanishi K, Hadoush H, Kurumadani H, Hashizume A, Sunagawa T, Ochi M.SourceDepartment of Neurology, Hiroshima Prefectural Hospital, Minami-ku, Hiroshima, Japan. kenin_04@yahoo.co.jp.
Human brain mapping.Hum Brain Mapp.2013 Jul;34(7):1559-67. doi: 10.1002/hbm.22012. Epub 2012 Mar 16.
Somatosensory evoked fields in response to compression (termed as Co) and decompression (termed as De) of glabrous skin (D1, thumb; D2, index finger; D5, little finger) were recorded. Although estimated equivalent current dipoles (ECDs) following stimulation of D1 and D5 were larger, but not signifi
PMID 22422717

Visual sensitivity shifts with perceived eye position.

Odoj B, Balslev D.SourceCenter of Neurology, University of Tübingen.
Journal of cognitive neuroscience.J Cogn Neurosci.2013 Jul;25(7):1180-9. doi: 10.1162/jocn_a_00382. Epub 2013 Mar 7.
Spatial attention can be defined as the selection of a location for privileged stimulus processing. Most oculomotor structures, such as the superior colliculus or the FEFs, play an additional role in visuospatial attention. Indeed, electrical stimulation of these structures can cause changes in visu
PMID 23469887

Japanese Journal

近赤外分光法を用いたウエストベルトによる被服圧下における脳活動計測

上前真弓,上前知洋,上條正義,井上正雄
日本感性工学会論文誌 14(3), 361-367, 2015
… In the somatotopic map of the postcentral gyrus by Penfield and Rasmussen, trunk sensations are located near the parietal region and intra-abdominal sensations are located near the lateral sulcus. …
NAID 130005095661

近赤外分光法を用いたウエストベルトによる被服圧下における脳活動計測

上前真弓,上前知洋,上條正義,井上正雄
日本感性工学会論文誌 advpub(0), 2015
… In the somatotopic map of the postcentral gyrus by Penfield and Rasmussen, trunk sensations are located near the parietal region and intra-abdominal sensations are located near the lateral sulcus. …
NAID 130005075197

Neural correlates of perceptual grouping effects in the processing of sound omission by musicians and nonmusicians.

Ono Kentaro,Altmann Christian F,Matsuhashi Masao,Mima Tatsuya,Fukuyama Hidenao
Hearing research 319, 25-31, 2014-11-07
… Omissions in the regular sequences were detected faster and evoked greater activity in the left Heschl's gyrus (HG), right postcentral gyrus, and bilateral superior temporal gyrus (STG) than did omissions in the irregular sequences. …
NAID 120005522497

Related Pictures

Postcentral Gyrus postcentral gyrus - Google Search | Brain anatomy, Brain diagram, Brain parts Level 2 - Sulci and Gyri - Human Neuroanatomy - Memrise PPT - precentral gyrus postcentral gyrus PowerPoint Presentation, free download - ID Precentral Gyrus, Central Sulcus, Postcentral Gyrus | Anatomy | Pinterest | Nervous Post Central Gyrus | Neurolink

★リンクテーブル★

リンク元	「中心後回」
関連記事	「postcentral」

「中心後回」

Postcentral gyrus
	Postcentral gyrus of the human brain
	Brodmann areas 3, 1 and 2 of human brain. Brodmann area 3 is in red, area 1 in green, and area 2 in yellow.
Details
Identifiers
Latin	Gyrus postcentralis
NeuroNames	hier-87
NeuroLex ID	Postcentral gyrus
TA	A14.1.09.128
FMA	61896
	Anatomical terms of neuroanatomy [edit on Wikidata]