Neurophysiology of Pain

Abstract

Psychiatry and pain are both complex phenomena that required a functional approach taking into account physiological, psychological and contextual domains. It is then not surprising that mental health and pain problems may have common sources. However, they can also be independents health problems that are interacting. The scientific literature is rich of example of comorbidity between mental health and pain problems. Moreover, the interaction is bidirectional. For instance, depression will increase the risk of developing chronic pain problems and vice versa. Some mental health problems such as schizophrenia or autism spectrum disorders have been linked to hypoalgesia while other mental disorders, such as anxiety or depression, are more related to hypoalgesia. As it will be developed in the other chapters, this linear relation between specific mental health problems and hypo- or hyperalgesia is too simplistic and not always true. In this chapter, we will introduce the neurophysiological basis of pain with an emphasis on endogenous excitatory and inhibitory mechanisms that share common basis in mental health and pain. We will discuss the mechanisms implicated in the development, persistency and treatment of pain. The main goal is to introduce the mechanisms of pain in functional terms so that the clinician can appropriate the link between pain and mental health.