Les bases anatomiques de la Théorie de l'Esprit: une revue de la littérature

Abstract

The theory of mind is the ability of human beings to mentalise about themselves and others in order to adapt their social behaviour. It is the principal element of social cognition. By understanding what people think, feel and intend, we can predict how people will behave and then, adapt our own behaviour. Even if the rudiments of the theory of mind are present early in life, usually only 4-year-old and older children are able to solve the false-belief tasks. At the moment, it is difficult to prove whether it is an independent cognitive function or whether it belongs to a more global cognitive process. It is necessary to learn the basis of social cognition and to understand the intentions of other individuals. More and more studies have tried to evaluate and analyse the neurophysiological and anatomical basis of the theory of mind. With different brain imaging studies the functions of the theory of mind become more and more evident. Today 13 functional MRI studies emphasise the critical role of medial prefrontal cortex in the theory of mind mechanism (Brodmann area 8/9). In fact, all the studies that used written theory of mind stories show that medial prefrontal cortex (BA8; extending into area BA9 and the anterior cingulated cortex) is activated while reading this type of stories. However, there is still some discrepancy concerning hemispheric dominance. Moreover, the medial prefrontal cortex is also activated in other cognitive tasks, especially concerning self-control, and the anterior paracingulate cortex plays a part in the cognitive aspects of emotions. Other brain regions, such as the temporal pole, the temporo-parietal junction, the amygdala, take also part in the mechanisms of mentalising and according to these different studies there is no predominant cerebral hemisphere. The activation of the temporal pole confirms the role of this brain part to generate the emotional and semantic context of our thoughts on the basis of our past experience. This information is necessary to adapt our behaviour to a new situation. The role of the superior temporal sulcus is not completely elucidated. It analyses the complex behaviour patterns, especially those of human beings. The amygdala takes part in the development of the theory of mind and helps to recognise the emotional expression of faces. In the studies of mentalising abilities in patients with acquired brain lesions, some results are even in contradiction with the functional MRI data and reveal mixed patterns of results. This can be explained by the biases in patient selection and the assessment methods used. In brain injury patients lesions of the orbito-frontal cortex result in theory-of-mind deficits, but the extension of lesions could influence these results. In a study with more circumscribed lesions the site of lesions does not reveal a link between the location of lesion and first- or second-order theory of mind impairment. On the contrary, this link is established between right prefrontal cortex and impairments in perspective taking and between medial frontal cortex and impairment in detection of deception. A ventral frontal lesion could disturb the ability to recognise facial emotional expressions. Further studies with larger groups of patients will be necessary to elucidate the theory of mind mechanisms and to determine their repercussions on social behaviour in case of brain injuries, especially frontal lesions.