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RESEARCH PRODUCT

Pain, Neural Basis of

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description

The term ‘pain’ refers on one hand to a subjective state of suffering, which is a conscious personal experience. On the other hand, pain is the percept that results from the activation of the nociceptive system. This specific sensory system is specialized for the detection of external stimuli and internal tissue states that threaten the integrity of the body. It is a part of the somatosensory system, but its peripheral and central neurons are separate from the tactile system. Functions such as the localization of painful stimuli or the discrimination of pain intensities are subserved by a projection pathway from thin peripheral nerve fibers, via processing centers in the spinal cord and lateral thalamus, to the somatosensory cortex. Other functions such as the negative hedonic quality or the motor drive to terminate the painful state are subserved by a parallel projection pathway involving medial thalamic nuclei, the insula and the limbic system. The nociceptive system is subject to neural plasticity, which enhances its sensitivity both in the peripheral and the central nervous system, and to a predominantly inhibitory descending control. A state of enhanced (hyperalgesia) or reduced pain sensitivity (analgesia) may occur, depending on the balance between these modulatory influences.