The role of the frontal lobes in anosognosia for Theory of Mind deficit: A single case study

Theory of Mind (ToM) refers to the ability to understand and predict others’ mental states. Frontal regions play a key role in ToM and lesion studies reported damages within the anterior cingulate and orbitofrontal cortices in adults showing ToM deficits. However, it is still debated the role of patients’ awareness of ToM deficits and its neural substrates. In this study, we investigated the anosognosia for ToM deficits. In this single-case study, we tested A.P., a traumatic brain injury (TBI) patient. The ToM abilities were investigated through ToM-test, Faux Pas, Eye Reading, and Irony-Comprehension test. The awareness was assessed by means of a non-structured interview, the Dysexecutive- Questionnaire, and the Patient-Competency-Rating-Scale. The Behavioral- Assessment-of-Dysexecutive-Syndrome was assessed as to control for the executive functioning. The neural correlates of patient’s specific deficits were investigated through a neuroanatomical study. The patient showed impaired performance during ToM assessments. Interestingly, he presented a selective lack of awareness for ToM deficits. His performance in the executive functions assessment was spared. The lesion analysis showed bilateral lesions in the orbitofrontal and lateral basal temporal regions. An explorative tracts analysis suggested damage of the arcuate fasciculus and the anterior cingulum. We reported a specific deficit in awareness regarding ToM impairment in a TBI patient. The lesion analysis suggested a role of the frontal lobe in anosognosia for ToM and supported the hypothesis of functional modularity in anosognosia (Mograbi & Morris, 2013). Further investigations are needed in order to better understand the networks involved in deficits of awareness.