Dissociation, Hemispheric Asymmetry, and Dysfunction of Hemispheric Interaction: A Transcranial Magnetic Stimulation Approach

The authors investigated the hypothesis that dissociation may represent a functional dysconnectivity syndrome using a transcranial magnetic stimulation (TMS) approach. Transcranial magnetic stimulation investigations that included motor thresholds and the transcallosal conduction time (TCT) reflecting the interhemispheric transfer were performed in 74 right-handed students. All subjects completed the Dissociative Experience Scale. The high dissociators had a significantly lower left hemispheric excitability than right hemispheric excitability. They also had a significantly shorter TCT from the left to the right hemisphere than did the low dissociators. These results suggest that the neural basis of dissociation may involve a cortical asymmetry with a left hemispheric superiority or, alternatively, a lack of right hemispheric integration.