The temporal poles (TPs) are among the brain regions that are often considered as the brain network sustaining our ability to understand other people's mental states or “Theory of Mind” (ToM). However, so far the functional role of the left and right TPs in ToM is still debated, and it is even not clear yet whether these regions are necessary for ToM. In this study, we tested whether the left TP is necessary for ToM by assessing the mentalizing abilities of a patient (C.M.) diagnosed with semantic dementia. Converging evidence from detailed MRI and 18 F-fluoro-2-deoxy- d -glucose PET examinations showed a massive atrophy of the left TP with the right TP being relatively unaffected. Furthermore, C.M.'s atrophy encompassed most regions of the left TP usually activated in neuroimaging studies investigating ToM. Given C.M.'s language impairments, we used a battery of entirely nonverbal ToM tasks. Across five tasks encompassing 100 trials, which probed the patient's ability to attribute various mental states (intentions, knowledge, and beliefs), C.M. showed a totally spared performance. This finding suggests that, despite its consistently observed activation in neuroimaging studies involving ToM tasks, the left TP is not necessary for ToM reasoning, at least in nonverbal conditions and as long as its right counterpart is preserved. Implications for understanding the social abilities of patients with semantic dementia are discussed.

A hallmark of human social interaction is the ability to consider other people's mental states, such as what they see, believe, or desire. Prior neuroimaging research has predominantly investigated the neural mechanisms involved in computing one's own or another person's perspective and largely ignored the question of perspective selection. That is, which brain regions are engaged in the process of selecting between self and other perspectives? To address this question, the current fMRI study used a behavioral paradigm that required participants to select between competing visual perspectives. We provide two main extensions to current knowledge. First, we demonstrate that brain regions within dorsolateral prefrontal and parietal cortices respond in a viewpoint-independent manner during the selection of task-relevant over task-irrelevant perspectives. More specifically, following the computation of two competing visual perspectives, common regions of frontoparietal cortex are engaged to select one's own viewpoint over another's as well as select another's viewpoint over one's own. Second, in the absence of conflict between the content of competing perspectives, we showed a reduced engagement of frontoparietal cortex when judging another's visual perspective relative to one's own. This latter finding provides the first brain-based evidence for the hypothesis that, in some situations, another person's perspective is automatically and effortlessly computed, and thus, less cognitive control is required to select it over one's own perspective. In doing so, we provide stronger evidence for the claim that we not only automatically compute what other people see but also, in some cases, we compute this even before we are explicitly aware of our own perspective.

A model of the functional and anatomical basis of belief reasoning is essential for understanding the relationship between belief reasoning and other cognitive processes in both normal development and pathology. Studies of brain-damaged patients can give valuable insights into the nature of belief processing but pose unique methodological problems. The current study addresses these problems by using a nonlinguistic belief-reasoning task with substantially reduced executive demands. A case series of 12 brain-damaged patients is presented. The belief-reasoning errors of four patients with damage to the prefrontal cortex appeared to arise from these patients' executive function problems. The belief-reasoning errors of three patients with damage to the temporo-parietal junction could not easily be accounted for in this way, raising the possibility that this brain region has a necessary role in representing beliefs, rather than handling the executive demands of belief-reasoning tasks. We discuss the importance of gaining empirical evidence about the scope of “theory of mind” impairments, and the important role for neuropsychological studies in this project.