EEG complexity and attentional processes related to dissociative states.

Reported findings indicate that attentional narrowing is related to decreased complexity and increased inhibition of neural assemblies. These findings suggest that analysis of electroencephalogram (EEG) complexity could present a useful method for research of attentional changes related to dissociation. To examine this model we used a case study to test the two hypotheses: (1) that successful anticonvulsant medication would result in dissociative symptom alleviation, improvement of inhibitory neural functions, and decreased EEG complexity, and (2) that cognitive conflict, related to aversive events in the patient's past experience, during reliving of a dissociative state would lead to greater allocation of attention and decreased EEG complexity. Three EEG studies recorded in the eyes closed non-drowsy state were performed: (1) at baseline, (2) post-induction of dissociative state, and (3) post-anticonvulsant medication following induction of dissociative state. A dissociative state was achieved following an interview regarding the patient's aversive past experiences through use of the Peritraumatic Dissociative Experiences Questionnaire (PDEQ). The patient's level of dissociation was measured using the Dissociative Experiences Scale-II (DES-II). The PDEQ interview and DES-II assessment were also used one hour following the oral consumption of an anticonvulsant medication (clonazepam 2mg). Analysis of the data revealed that complexity values (PD2) are significantly lower following the oral consumption of clonazepam (2mg) in the majority of EEG channels. Additionally, complexity during the reliving of a dissociative state was statistically significantly lower than both the baseline and post-medication conditions in all but two EEG channels. Results of the case study suggest that changes in attentional processes linked to dissociation are related to: (1) decreased complexity when attention is extremely focused because of attentional narrowing to the disturbing past experience, and (2) increased complexity during ordinary experiences when attention is less narrowly focused.