Fig. 2. A common pathophysiology for irritable bowel syndrome (IBS) and functional movement disorders (FMD) in a Bayesian perspective. Recent hypotheses in psychosomatic medicine suggest that functional symptoms might arise when excessive attention is granted to abnormal prior beliefs, located at an intermediate level in the cortical hierarchy. In line with this framework, here we propose that the aberrant frontal activation shown by both patients with FMD and with IBS may account for the abnormal attention allocated to the aberrant priors, which may be located in supplementary motor area (SMA) in FMD, and in the insula and secondary somatosensory cortex (S2) in IBS.
79,81 Anterior insula has been hypothesized by several authors as a possible neural substrate for the comparator system between predictions and errors in the interoceptive domain.
82,83 Finally, the amygdala may have a predominant role in the creation and maintenance of these priors.
79 PFC, prefrontal cortex.
