Nociception and pain
One of the essential functions of the nervous system is to give a sensing interface that provides information about the environment. The somatosensory system thus responds to changes on the surface or within the body, and when these environmental changes are harmful or potentially harmful, this nociceptive information can result in pain. This unpleasant experience involves several components (sensory discriminative, emotional, behavioural, cognitive and adaptive) and results from complex processing in sets of brain structures often referred to as the "pain matrix". While acute pain has an adaptive value, chronic pain is a pathological state that alters the quality of life and is often associated with co-morbid disorders (e.g. anxiety, depression, cognitive disorders, risk of addiction...).