Primary somatosensory cortex
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.[1] 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).Each cerebral hemisphere of the primary somatosensory cortex only contains a tactile representation of the opposite (contralateral) side of the body.[3][4] 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 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.
Anatomical terms of neuroanatomyneuroanatomypostcentral gyrusparietal lobesomatosensory systemWilder PenfieldBrodmann areas 3, 1 and 2thalamocortical projectionscerebral hemispheretactile receptorsBrodmannposterioragraphesthesiaastereognosiahemihypesthesiavibrationproprioceptionfine touchhemineglectnociceptionthermoceptioncrude touchspinothalamic tractinsular cortexcingulate gyrusList of regions in the human brainNeuroNamescerebral cortexhuman brainFrontal lobePrefrontalSuperior frontal gyrusMiddle frontal gyrusInferior frontal gyrusPars orbitalisBroca's areaPars opercularisPars triangularisSuperior frontal sulcusInferior frontal sulcusPrecentralPrecentral gyrusPrecentral sulcusMedial frontal gyrusParaterminal gyrusParaolfactory areaStraight gyrusOrbital gyriOrbitofrontal cortexVentromedial prefrontal cortexSubcallosal areaOlfactory sulcusOrbital sulcusParacentral lobuleParacentral sulcusPrimary motor cortexPremotor cortexSupplementary motor areaSupplementary eye fieldFrontal eye fieldsSuperior parietal lobuleInferior parietal lobuleSupramarginal gyrusAngular gyrusParietal operculumIntraparietal sulcusPrecuneusMarginal sulcus3, 1 and 2Secondary somatosensory cortexPosterior parietal cortexOccipital lobeOccipital gyriLateral occipital gyrusLunate sulcusTransverse occipital sulcusVisual cortexCuneusLingual gyrusCalcarine sulcusTemporal lobeTransverse temporal gyrusAuditory cortex41 and 42Superior temporal gyrusWernicke's areaPlanum temporaleSuperior temporal sulcusMiddle temporal gyrusOccipitotemporal sulcusFusiform gyrusMedial temporal lobeInferior temporal sulcusInferior temporal gyrusInterlobarsulci/fissuresCentral (frontal+parietal)Lateral (frontal+parietal+temporal)Parieto-occipitalPreoccipital notchLongitudinal fissureCingulate (frontal+cingulate)Collateral (temporal+occipital)Callosal sulcusLimbic lobeParahippocampal gyrusEntorhinal cortexPerirhinal cortexPostrhinal cortexPosterior parahippocampal gyrusPrepyriform areaCingulate cortexSubgenual areaAnterior cingulatePosterior cingulateIsthmus of cingulate gyrusRetrosplenial cortexHippocampal formationHippocampal sulcusFimbria of hippocampusDentate gyrusRhinal sulcusIndusium griseumAmygdalaOperculumBrodmann areasspinal cord