Altered neural synchrony during semantic processing of nonverbal emotional expressions in individuals with alexithymia

Alexithymia is a subclinical personality trait characterized by difficulty in identifying and describing feelings and has been linked to deficits in processing nonverbal emotional expressions. However, the neural mechanisms through which alexithymia affects the semantic processing of such expressions remain unclear. To address this gap, 57 participants were recruited and categorized into high alexithymia (HA; n = 29) and low alexithymia (LA; n = 28) groups based on their scores on the Toronto Alexithymia Scale. We utilized task-based functional magnetic resonance imaging to assess group differences in inter-subject neural synchrony during the semantic processing of nonverbal emotional expressions. The results revealed significantly greater inter-subject correlation (ISC) in the HA group than in the LA group, indicating enhanced neural synchrony among individuals with HA. Specifically, increased ISC was observed in the cuneus and the orbital part of the inferior frontal gyrus. Further analyses demonstrated that the supramarginal gyrus and the temporal pole of the middle temporal gyrus may be involved in the semantic processing of nonverbal emotional expressions. These findings provide evidence for altered neural synchrony during the semantic processing of nonverbal emotional expressions in individuals with HA and offer new insights into the neural mechanisms underlying individual differences in the processing of nonverbal emotional expressions.