Intro | A-Delta Fiber | C Fiber | Somatosensory Cortex | Midbrain | Midline Nucleus of the Thalamus | Ventrobasal Nucleus of the Thalamus | Descending Neural Pathway | Spinal Cord | Thalamus
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
Somatosensory Cortex is responsible for the perception of several sensations: tactile pressure or touch, temperature, and pain. Somatosensory cortex is located in the parietal lobe just behind the central sulcus that separates frontal lobe from parietal lobe. Somatosensory cortex is organized according to receptive fields that represent the activity within particular regions of skin.
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Somatosensory cortex is organized with the representation of body structures occurring within specific regions of the gyrus. This distribution of body representation is called a homunculus (or a "dwarf" of disproportionate parts). Regions of the body with the greatest sensitivity to somatosensation, are represented by the largest amount of cortical tissue; with the lips, tongue, hands, and fingers representing the largest proportion of tissue and the genitalia following closely behind. Damage to somatosensory cortex results in remarkably mild deficits. Surgical removal of this region in one hemisphere results in a reduced ability on the opposite side of the body in the detection of light touch and some difficulty identifying objects by touch (stereognosis). Two specific stereognoses that may follow damage to somatosensory cortex are asterognosia, the inability to recognize objects by touch, and asomatognosia, the inability to recognize parts of one's own body. Damage that extends further into parietal lobe may result in anosognosia, the inability to recognize one's own neurological symptoms, and contralateral neglect, the tendency to ignore stimuli on the opposite side of the body. Contralateral neglect occurs more frequently following damage to the right hemisphere.