The effects of pain on behavior resonate far beyond the immediate pain experience. Indeed, very often the mere prospect of future pain is sufficient to drive avoidance. While avoiding future pain may appear like a reasonable biological imperative, this often comes at a cost and excessive pain avoidance can have disastrous effects on health and well-being and contribute to pain-related disability. Unfortunately, little is known about the way that pain is represented in the human brain when making decisions about future pain outcomes.
Goal
The main objective of this study was to examine how the brain represents future painful outcomes when making decisions about pain. The research team further aimed to test whether this representation was similar or distinct to the representation of monetary rewards, experienced pain and negative emotions elicited by aversive pictures.
Methodology
The researchers designed a functional magnetic resonance study in which participants were asked to choose between one of 10 levels of pain induced by electrical stimulations and one of 10 levels of monetary rewards. In order to obtain the rewards, participants had to experience the pain. Machine learning was used to identify a multivariate brain signature predicting the intensity of the potential future pain involved in each decision. The research team then compared this representation to the multivariate signatures predicting the amount of monetary reward, the intensity of experienced shocks and the intensity of aversive pictures.
Results
Results show that a distributed pattern of activity encodes the value of future pain comprising both unsigned saliency signals (positively related to more pain and more money) and signed valuation signals (positively related to money and negatively related to pain). This pattern can predict the intensity of future pain involved in economic decisions and participants’ decisions to accept or avoid the pain stimulation. This representation is partly related to the representation of monetary reward and negative valence but distinct from the representation of physical pain.
Take home message
These results identify a specific representation of the value of future pain in the brain and significantly contribute to further our understanding of the cerebral mechanisms responsible for making decisions about future pain. These findings could have potentially important implications for our understanding of disorders characterized by excessive or insufficient pain avoidance.
