ABSTRACT
Theory of Mind (ToM) is the ability to infer other people's mental states like intentions or desires. ToM can be differentiated into affective (i.e., recognizing the feelings of another person) and cognitive (i.e., inferring the mental state of the counterpart) subcomponents. Recently, subcortical structures such as the basal ganglia (BG) have also been ascribed to the multifaceted concept ToM and most BG disorders have been reported to elicit ToM deficits. In order to assess both the correlates of affective and cognitive ToM as well as involvement of the basal ganglia, 30 healthy participants underwent event-related fMRI scanning, neuropsychological testing, and filled in questionnaires concerning different aspects of ToM and empathy. Directly contrasting affective (aff) as well as cognitive (cog) ToM to the control (phy) condition, activation was found in classical ToM regions, namely parts of the temporal lobe including the superior temporal sulcus, the supplementary motor area, and parietal structures in the right hemisphere. The contrast aff > phy yielded additional activation in the orbitofrontal cortex on the right and the cingulate cortex, the precentral and inferior frontal gyrus and the cerebellum on the left. The right BG were recruited in this contrast as well. The direct contrast aff > cog showed activation in the temporoparietal junction and the cingulate cortex on the right as well as in the left supplementary motor area. The reverse contrast cog > aff however did not yield any significant clusters. In summary, affective and cognitive ToM partly share neural correlates but can also be differentiated anatomically. Furthermore, the BG are involved in affective ToM and thus their contribution is discussed as possibly providing a motor component of simulation processes, particularly in affective ToM.
ABSTRACT
Theory of Mind (ToM), which is the ability to infer other people's mental states such as beliefs or desires, is an important prerequisite for social interaction. Affective and cognitive subcomponents of ToM can be impaired selectively in neurological and psychiatric disorders. This study examines ToM in 21 Parkinson's disease (PD) patients and 21 healthy control (HC) subjects, using the computerized "Yoni task" that assesses affective and cognitive ToM abilities and an extensive battery of neuropsychological tests. Furthermore, questionnaires to assess health-related quality of life and depressive symptoms were applied and correlations to ToM were investigated. Compared to the control subjects, PD patients scored lower on both the affective (PD: 76% versus HC: 89%; p = 0.006) and cognitive (PD: 80% versus HC: 92%; p = 0.002) ToM subscales but not on control items (PD: 90% versus HC: 95%; p = 0.077). The ToM abilities were not associated with other cognitive functions, depressive symptoms or clinical data. However, affective ToM was correlated with health-related quality of life (p = 0.01). Parkinson patients are impaired in affective as well as cognitive ToM. These deficits are largely independent from other cognitive impairments, depressive symptoms and motor impairment. The relationship of affective ToM to the health-related quality of life of PD patients points to a clinical relevance of this issue and suggests that ToM dysfunctions must be regarded as an important non-motor feature of Parkinson's disease.
