We combine electrophysiological studies with functional anatomical approaches to investigate the organisation and activation of descending control systems that originate in the midbrain and hypothalamus which act to modulate spinal nociception and autonomic outflow. These systems most likely underlie the co-ordinated patterns of change in nociceptive responsiveness and autonomic outflow that occur:
• during fever, as part of a sickness response
• in different behavioural states, such as fear and anxiety
• in certain pathophysiological conditions, such as stress related disorders and chronic pain.
We have recently developed a technique to preferentially activate different classes of nociceptive afferents; A- and C- nociceptors. These afferents signal different qualities of the pain message and have diferent roles in the initiation and maintenance of chronic pain states. As such, this new approach provides a very powerful tool with which to study mechanisms of acute and chronic pain, including the role of descending control.