Central sensitization of the spino‐parabrachial‐amygdala pathway that outlasts a brief nociceptive stimulus

Chronic pain is disabling because sufferers form negative associations between pain and activities, such as work, leading to the sufferer limiting these activities. Pain information arriving in the amygdala is responsible for forming these associations and contributes to us feeling bad when we are in pain. Ongoing injuries enhance the delivery of pain information to the amygdala. If we want to understand why chronic pain can continue without ongoing injury, it is important to know whether this facilitation continues once the injury has healed. In the present study, we show that a 2 min noxious heat stimulus, without ongoing injury, is able to enhance delivery of pain information to the amygdala for 3 days. If the noxious heat stimulus is repeated, this enhancement persists even longer. These changes may prime this information pathway so that subsequent injuries may feel even worse and the associative learning that results in pain‐related avoidance may be promoted.