Imagining pain can make it so

Perhaps one of the ways in which chronic pain reinforces itself is because people are exposed to the pain either constantly or repeatedly (in the case of recurring pain conditions) and so become exceedingly familiar with how it feels. This familiarity can fuel more complete and vivid imagining of the pain experience, which may very well exacerbate the pain. Indeed, it may very well that it is not fear per se that is the problem when people anticipate pain, but rather than they are imagining what the pain will feel like and it is the mental “picture” of the pain in advance of any actual pain, which evokes fear.

Evidence now exists that simply imagining pain can actually activate much of the same pain circuits in the brain that are typically involved during the experiencing of painful stimuli.

Allodynia is a condition in which normally innocuous or even pleasurable tactile sensations are perceived as painful. Kramer et al (2008) showed that by imagining touch as painful (imagined allodynia) activates the same neural structures as actual allodynia. They divided healthy participants into two groups. The first group had previously been exposed to experimentally induced allodynia within the past 6 months. The second group had no experience with allodynia and so did not know what touch-evoked pain is like. Both groups received tactile stimulation on hand and then the other, but they were asked to imagine that the sensation on the right hand was painful. Non-painful tactile stimulation activated contralateral S1 and S2 (see top panel of figure below). During imagination of allodynic pain in the right hand, there was activation in the ACC and Insula and medial frontal cortex in addition to contralateral S1 and bilateral S2 (see lower panel of figure below).



Thus, people who have had prior experience with allodynia are able to conjure up the experience in their imaginations and when they do, the brain regions normally associated with painful touch sensations become activated. Those with more allodynia experience showed more pronounced activation in the contralateral S1, mid insula, inferior frontal cortices, ACC and ipsilateral amygdala (see figure below):