Dictionary of Biological Psychology
Touch is the class of sensations produced by mechanical disturbances of the skin from physical contact or thermal stimulation. Vibration, PAIN, pressure, and TEMPERATURE are encoded via fine nerve endings and the MECHANORECEPTOR system. The most sensitive body regions (tongue, lips, fingers) have the greatest density of mechanoreceptors and the largest cortical representation. Impulses travel along sensory nerve fibres to SOMATOSENSORY PATHWAYS, the THALAMUS, and SOMATOSENSORY CORTEX (Kaas, 1988).
Somatosensory cortex maintains somatotopic organization. Primary somatosensory cortex (S-I) processes primary sensations; damage to S-I produces numbness. Secondary somatosensory cortex (S-II) processes complex tactile information; damage to S-II or higher-level association areas may produce TACTILE AGNOSIA.
See also: haptic; homunculus; sensory transduction;
Reference
Iwamura Y. (1998) Hierarchical somatosensory processing. Current Opinion in Neurobiology 8:522–528.
CATHERINE L.REED
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