Dissociating cognitive from affective theory of mind: A TMS study

Investigated the role of the right dorsolateral prefrontal cortex (DLPFC) in cognitive theory-of-mind (ToM) as opposed to affective ToM processes. Subjects included 28 males with a mean age of 24 years who were screened for cognitive dysfunction using a reasoning subtest of the German intelligence test battery Leistungspruefungssystem (LPS), and the Trail Making Test A and B (TMT). The site used for repeated transcranial magnetic stimulation (rTMS) was located in subjects using MRI. 1 Hz rTMS was used to interfere offline with cortical function of the right DLPFC. Immediately following stimulation, subjects were tested with the German version of the Yoni ToM task in which ability to judge mental states via the analysis of verbal cues, eye gaze, and facial expression was assessed. Items on the task were categorized as either cognitive ToM items, affective ToM items, or control physical condition. Results showed a selective effect of rTMS over the right DLPFC on performance in cognitive ToM items but not in affective ToM items. Furthermore, rTMS over the right DLPFC was associated with an acceleration of reaction times in cognitive ToM items. In addition, the reaction times in affective ToM items were consistently faster than reaction times in cognitive ToM items in both conditions. It is concluded that the exact role of the right DLPFC in networks mediating ToM was unidentifiable, and possible explanations of the results are discussed. Cognitive ToM functions are assumed to be independent from affective ToM, and the important role of the right DLPFC in ToM should be further explored.