Abstract
Impaired Theory of Mind (ToM) has been repeatedly reported as a feature of psychotic disorders. ToM is crucial in social interactions and for the development of social behavior. It has been suggested that reasoning about the belief of others, requires inhibition of the self-perspective. We investigated the neural correlates of self-inhibition in nineteen low psychosis prone (PP) and eighteen high PP subjects presenting with subclinical features. High PP subjects have a more than tenfold increased risk of developing a schizophrenia-spectrum disorder. Brain activation was measured with functional Magnetic Resonance Imaging during a ToM task differentiating between self-perspective inhibition and belief reasoning. Furthermore, to test underlying inhibitory mechanisms, we included a stop-signal task. We predicted worse behavioral performance for high compared to low PP subjects on both tasks. Moreover, based on previous neuroimaging results, different activation patterns were expected in the inferior frontal gyrus (IFG) in high versus low PP subjects in self-perspective inhibition and simple response inhibition. Results showed increased activation in left IFG during self-perspective inhibition, but not during simple response inhibition, for high PP subjects as compared to low PP subjects. High and low PP subjects showed equal behavioral performance. The results suggest that at a neural level, high PP subjects need more resources for inhibiting the self-perspective, but not for simple motor response inhibition, to equal the performance of low PP subjects. This may reflect a compensatory mechanism, which may no longer be available for patients with schizophrenia-spectrum disorders resulting in ToM impairments.
Highlights
The capacity to understand other people’s mental states or Theory of Mind (ToM) is crucial in social interactions and for the development of social behavior
In line with Samsons results, self-perspective inhibition was mediated by the bilateral inferior frontal gyrus (IFG) with a more prominent role for the left IFG [39], while belief reasoning was mediated by the left superior temporal gyrus (STG), temporoparietal junction (TPJ) and middle temporal gyrus (MTG)
The data revealed more activation in the left IFG for high compared to low psychosis prone (PP) individuals on ToM during selfperspective inhibition, despite equal behavioral performance
Summary
The capacity to understand other people’s mental states or Theory of Mind (ToM) is crucial in social interactions and for the development of social behavior. ToM is a broad concept referring to the ability to understand other people’s mental state, the understanding that another person may have a different belief, and the understanding of the others’ subsequent behavior [1]. This ToM ability relies upon a wide network of brain areas, most importantly encompassing lateral frontal, medial frontal and temporal areas (see [2] and [3] for a more detailed account of the neurobiological underpinnings of ToM). Even though patients in the acute phase of the disorder are more impaired than remitted patients, the latter group still demonstrates significant impairments in ToM [5]
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