Objectives: To assess the association between dMPFC function and individual differences in alexithymia during high-level self-representation.
Methods: 29 adult males (18-45 years old) with a diagnosis of an autism spectrum condition (ASC), and 33 age-, sex-, and IQ-matched neurotypical adults were scanned with fMRI at 3T while making mentalizing or physical judgments about themselves or a non-close other. Regions analyzed were dMPFC, medial orbitofrontal cortex (mOFC), bilateral anterior insula (AI), and bilateral amygdala (Amyg).
Results: Replicating past research, individuals with ASC report more alexithymic traits than neurotypical individuals. In the neurotypical group, Increases in alexithymia were associated with increases in dMPFC activity (r = 0.57, p = 0.0005). However, in the ASC group this association was absent (r = -0.01, p = 0.95). The difference in these correlations between-groups was significant (z = 2.45, p = 0.01). No other region was associated with individual differences in alexithymia in either group (-0.16 < r < 0.21, p > 0.23).
Conclusions: The dMPFC is critical for metarepresentational ability; particularly in appraising subjective emotional experience. In the absence of stimulus-driven processing, increasing alexithymia was strongly associated with increased recruitment of dMPFC during self-mentalizing in the neurotypical group. However, although individuals with ASC report more alexithymia than that of neurotypical individuals, the magnitude of alexithymia was not associated with dMPFC activity. It is likely that the altered neurodevelopment of dMPFC in autism derails the normative role of dMPFC in metarepresentational function. However, the magnitude of alexithymic difficulty in ASC is likely to involve deficits in other aspects of emotion processing besides metarepresentation (e.g., bottom-up emotion processing).