Individual differences in alexithymia and brain response to masked emotion faces

Alexithymia is considered a dimensional personality trait that refers to a cluster of deficits in the recognition, differentiation, and verbalization of emotions. Research on the neurobiology of alexithymia has focused hitherto on impairments in the controlled processing of emotional information. In the present study automatic brain reactivity to facial emotion was investigated as a function of alexithymia (as assessed by the 20-Item Toronto Alexithymia Scale - TAS-20). During 3T fMRI scanning, pictures of sad, happy, and neutral facial expression masked by neutral faces were presented to 33 healthy women. A priori regions of interest in the whole brain analysis were cerebral structures that are known to be crucially involved in the emotion perception from the face. Independently from trait anxiety and depression TAS-20 alexithymia was negatively correlated with activation to masked sad and happy faces in several regions of interest (in particular, insula, superior temporal gyrus, middle occipital and parahippocampal gyrus). In addition, the TAS-20 score was negatively correlated with response of the left amygdala to masked sad faces. A reduced automatic reactivity of the amygdala and visual occipito-temporal areas could implicate less automated engagement in the encoding of emotional stimuli in high alexithymia. In addition, a low spontaneous insular and amygdalar responsivity in high alexithymia individuals could be related to an attenuation of basic emotional experiences which may contribute to problems in identifying and differentiating one's feelings.