Somatosensation and Pain

The somatosensory system is responsible for processing proprioceptive, thermal, touch, and pain information from the body surface and internal tissues. The skin is in fact the largest sensory organ in the body. Braille readers demonstrate a capacity to use discriminative touch in ways most of us will never develop, yet all of us can appreciate different textures. Somatosensation provides sensory feedback which, although mostly subconscious, is crucial for many motor activities. Among somatic modalities, pain is notable for attracting our immediate attention. Normal pain caused by intense (noxious) stimuli alerts us to danger and thus serves an important adaptive role, and the heightened sensitivity associated with inflammatory pain facilitates our recovery from injury. But abnormal processing of somatosensory information can result in chronic neuropathic pain, a disease in its own right. This chapter addresses normal somatosensation and how its disruption can result in chronic pain.