Emotional regulation of pain: the role of noradrenaline in the amygdala.

The perception of pain involves the activation of the spinal pathway as well as the supra-spinal pathway, which targets brain regions involved in affective and cognitive processes. Pain and emotions have the capacity to influence each other reciprocally; negative emotions, such as depression and anxiety, increase the risk for chronic pain, which may lead to anxiety and depression. The amygdala is a key-player in the expression of emotions, receives direct nociceptive information from the parabrachial nucleus, and is densely innervated by noradrenergic brain centers. In recent years, the amygdala has attracted increasing interest for its role in pain perception and modulation. In this review, we will give a short overview of structures involved in the pain pathway, zoom in to afferent and efferent connections to and from the amygdala, with emphasis on the direct parabrachio-amygdaloid pathway and discuss the evidence for amygdala's role in pain processing and modulation. In addition to the involvement of the amygdala in negative emotions during the perception of pain, this brain structure is also a target site for many neuromodulators to regulate the perception of pain. We will end this article with a short review on the effects of noradrenaline and its role in hypoalgesia and analgesia.