Objectives: To assess how the neural response to self-mentalizing is modulated by individual differences in alexithymia.
Methods: 23 adult males (18-45 years old) with a diagnosis of Asperger Syndrome and 23 age-, sex-, and IQ-matched neurotypical adults were scanned at 3T during fMRI while making mentalizing judgments about themselves or a non-close other. Alexithymia was measured using the Toronto Alexithymia Scale (TAS-20).
Results: Among neurotypical adults, alexithymia positively correlated with self-mentalizing BOLD response in the caudal anterior cingulate cortex (cACC; r = 0.78) and anterior insula (AI; r = 0.59). In ASC, alexithymia positively correlated with self-mentalizing BOLD response in ventral medial prefrontal cortex (VMPFC; r = 0.62). Alexithymia differently modulated activity in cACC depending on diagnostic status. Neurotypical participants activated cACC more with increasing alexithymia, while in ASC, cACC was less active with increasing alexithymia.
Conclusions: Our results highlight the importance of cACC in self-referential cognitive difficulties. The cACC is highly involved during interoceptive awareness (Critchley et al., 2004, Nat Neurosci) and affective processing of pain (Singer et al., 2004, Science). While neurotypical individuals tend to use cACC more with increasing levels of alexithymia, individuals with ASC use cACC less as alexithymia increases. We conclude that mindblindness in relation to the self in ASC is related to decreased recruitment of a brain region essential for reading one's own bodily states and emotions.