Biological Basis of Mind-Blindness
Neural correlates of the ToM point towards three regions of the brains. The anterior paracingulate cortex (Brodmann), is considered at the key region of mentalizing. It is located anterior corpus callosum and the anterior cingulate cortex. This cortex is associated with the medial frontal cortex where activation is associated with the mentalization of states. The cells of the ACC develops at the age of 4 months suggesting that the manifestations of mind-blindness may occur around this time.
In addition to the anterior paracingulate cortex is the superior temporal sulcus and the temporal poles that are involved with the ToM and it’s pathology. However, these areas are not uniquely associated with mentalization. They aid in the activation of the regions that are associated with the ToM. The superior temporal sulcus is involved in the processing of behavioural information while the temporal poles are involved in the retrieval of personal experiences. These are considered important regions for the activation of the ToM regions and are associated with the mind-blindness. The temporal poles provide personal experiences for mentalization such as facial recognition, emotional memory and familiar voices. In patients suffering from semantic dementia, the temporal regions of these patients undergo atrophy and lead to certain deficits which can cause mind-blindness.
The amygdala and the orbitofrontal cortex also are a part of the ToM. It is in involved in the interpretation of behaviour which plays an important role in social cognition and therefore contributes to the theory of the mind. It is suspected that the damage to the orbitofrontal cortex brings upon subtle impairments, but not a total loss of the ToM that would to mind-blindness. Some studies over the years have shown that the orbitofrontal cortex is not directly associated with the theory of the mind or mind-blindness**. However a study by Stone and fellow colleagues were able to show impaired ToM on mentalisation tasks.
Since the frontal lobe is associated with executive function, researchers theorize that the frontal lobe plays an important role in ToM and its associated pathology. It has also been suggested that the executive function and the theory of mind share the same regions. Despite the fact that ToM and mind-blindness can explain executive function deficits, it is argued that autism is not identified with the failure of the executive function.
Lesion studies show that when lesions are imposed to the medial frontal lobe, performance on mentalization tasks is reduced, similar to typical mind-blindness cases. Patients that experienced frontal lobe injuries due to severe head trauma showed signs of mind blindness, as a result of a lost ToM. However it is still debated whether the inactivation of the medial frontal lobe is involved in the mind-blindness.
Frith and Frith proposed that a neural network that comprised the medial prefrontal cortex, the anterior cingulate cortex and the STS, is crucial for the normal functioning of ToM and self monitoring. This so formed dorsal system is crucial for social cognition. Disruption of this neural network leads to mind-blindness in schizophrenic individuals.
Another clue towards a possible explanation of mind-blindness in autism was done by Castelli and colleagues. They were able to show that the connectivity between occipital and the tempero-parietal regions were weaker in the autistic group than the control group. The under activation of this network may inhibit the interactive influences between regions that process higher and lower perceptual items.
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