Central Neural Mechanisms that Interrelate Sensory and Affective Dimensions of Pain

Afferent pathways for pain and descending brain-to-spinal cord modulatory pathways. Left: ascending pathways for pain, including receptors and primary afferent neurons, ascending spinothalamic tract, and thalamocortical pathways to somatosensory cortex. Right: descending pain modulatory pathways. This system originates in cerebral cortical areas, including amygdala, and projects to central grey. The latter, in turn projects to cells of the rostroventral medulla, which in turn project to the dorsal horn. Both inhibitory and facilitatory effects are exerted at the level of the dorsal horn. Thus, there is bi-directional control of nociceptive transmission at this level.