The brain mechanisms related to formal thought disorders (FTD) and auditory verbal hallucinations (AVH) appear to be closely linked to structural and functional abnormalities of the language system.

In particular, functional imaging data indicate that several components of the language system are involved in the generation of both, FTD and AVH. Co-activation of the primary auditory cortex (Heschl's gyrus) during verbal thoughts appears to be crucial for the subjective perception of an externally generated voice, and DTI studies indicated that the intrahemispheric fronto-temporal connectivity of the language system is specifically increased in hallucinating patients. On the other hand, FTD are significantly correlated to a gray matter reduction in Wernicke's region along with a hyperactivation of frontal and temporal components of the language system.

AVH are intimately related to a dysfunction of the left hemispheric language system, including the primary auditory cortex and the fronto-temporal fibre tracts connecting Broca's and Wernicke's regions. Co-activation of the primary auditory cortex during verbal thoughts appears to be the basis of the pathological network dynamics during AVH, while FTD are linked to a pathological hyperactivity of central components of the language system. Both phenomena are related to functional imbalances of the language system, and phenomenological differences may depend on the different contributions of the system components.