Dissociative Tendency, Anger Expression, and Frontal Activation During a Verbal Fluency Task

Abstract

Background: Brain mechanisms underlying dissociation or impulsivity have been a focus of research in adolescent mental health. Functional imaging studies have shown an association of both behaviors with frontal functioning. Methods: We investigated frontal lobe activation during word productions using 16-channel near infrared spectroscopy (NIRS), and examined correlations between relative changes in cerebral blood volume and behaviors according to the state-trait anger expression inventory (STAXI-1) and the adolescent dissociative experience scale (ADES) in 44 healthy university students (mean age 20.2 years; 29 females). In addition, we compared frontal activations by dissociation levels. All subjects gave written informed consent according to the provisions of the Declaration of Helsinki revised in Edinburgh in 2000. We strictly protected privacy, and anonymity was carefully preserved. Results: Verbal fluency provided widespread and gradual frontal activations in general, and significant differences in activations were noted in the right prefrontal cortex (PFC), lower in ch1, 2 and 7 (dorsolateral to the ventral portion), and higher in ch13 and lower in ch16 (left PFC) with stronger dissociation tendencies. Total ADES and Anger-in scale (the frequency with which angry feelings are suppressed) of the STAXI correlated significantly and negatively with frontal pole activation (ch8). Conclusions: Differences in frontal activation suggest that dissociation might be related to the PFC. The present study also suggests that lack of anger suppression could be associated with stronger rostral PFC activation.