Updating peripersonal space and body representation whilst experiencing pain

The multisensory representations of our body and its surrounding space are constantly updated as we interact with objects in our environment, for instance during active tool-use. People with certain painful conditions often present with distorted representations of their body and peripersonal space, compared to pain-free individuals. It has been proposed that disruption to the processes involved in updating these representations could underlie some painful conditions. For instance, we have demonstrated that people with Complex Regional Pain Syndrome have difficulties with updating the representation of their affected limb. However, it is not known how such updating problems may arise: for example, if they reflect a difference in cognitive processing that pre-dated the development of pain, or if they are a consequence of pain. To test the latter, we induced pain in healthy individuals using 1% Capsaicin cream and examined its effect on participants’ abilities to update the representation of their body and peripersonal space during tool-use. Updating of the body representation was examined by comparing tactile distance judgements on participant’s arms before and after tool-use. Updating of peripersonal space representation was examined during active tool-use by measuring changes in reaction times and error rates to vibro-tactile stimulation at the handles of the tools in the presence of visual distractors. Induced pain did not alter performance on either task when compared to control conditions. This suggests that acute pain is not sufficient to account for the distorted representations of the body and its surrounding space commonly observed in people with painful conditions.