Believing is seeing: an fMRI study of thought-action fusion in healthy male adults.

Thought-action fusion (TAF) is a tendency of individuals to establish causal relations between their own thoughts and external reality. TAF can lead to maladaptive behaviors typically observed in obsessional thoughts. However, neural mechanisms underlying TAF are still unknown. In this study, 38 healthy men were informed that MR signals were able to detect thoughts of the word 'apple' and that this recognition could result in the administration of electrical shocks to a person outside the scanner. During MR acquisition, they were asked to suppress or not suppress the thought of 'apple' while sham electrical shocks were or were not administered to the other person. The main effect of the sham administration of electrical shock to another person was shown in the bilateral lingual gyri, fusiform gyri, and middle occipital cortices (FDR corrected p < 0.05). Also, fusiform gyrus, lingual gyrus, and middle occipital cortex activity correlated with scores of guilty feeling only when participants consciously tried to think of apple as less as possible. Our study demonstrates that visual association areas may play primary roles in TAF. The simple belief and visual imagery that one's thought may lead to someone's injury activated visual areas of the brain where, in turn, brain activity is associated with feelings of guilt.