Neurophysiological correlates of increased verbal working memory in high-dissociative participants: a functional MRI study.
BACKGROUND
Dissociation, defined as a disruption in usually integrated mental functions, is found not only in DSM-IV dissociative disorders, but also in post-traumatic stress disorder and eating disorders. Dissociative phenomena are also common in the general population, and may reflect a constitutionally determined cognitive style rather than a pathological trait acquired through experiencing adverse life events. In pathological dissociation, evidence has been presented for episodic memory dysfunction. In contrast, in high-dissociative subjects increased performance has been found for episodic memory and dual task performance. These findings have been linked to changes in working memory capacity.


METHODS
In the present study, the authors sought to extend these findings by using functional magnetic resonance imaging during performance of two parametric working memory tasks. We tested 21 healthy low- and high-dissociative participants.


RESULTS
High-dissociative participants performed slightly better during both tasks. Imaging data showed that both groups activated similar networks for both tasks, i.e. (bilateral) dorsolateral (DL) and ventrolateral prefrontal cortex (PFC), parietal cortex, and supplementary motor area. Group x task interactions were found in the high-dissociative group in L DLPFC and L parietal cortex; in the low-dissociative group in R fusiform gyrus. The differences in the high-dissociative group were independent from performance differences, implying that high-dissociative subjects generally recruit this network to a greater extent.


CONCLUSIONS
These results confirm earlier findings using a verbal WM task in high-dissociative participants, and are compatible with the conceptualization of non-pathological dissociation as an information-processing style, characterized by distinct attentional and mnemonic abilities.
Veltman
Dick J
DJ
Department of Psychiatry & Clinical PET Center, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
de Ruiter
Michiel B
MB
Rombouts
Serge A R B
SA
Lazeron
Richard H C
RH
Barkhof
Frederik
F
Van Dyck
Richard
R
Dolan
Raymond J
RJ
Phaf
R Hans
RH
D000328:Adult; D001921:Brain / Q000502:physiology*; D016022:Case-Control Studies; D004213:Dissociative Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007802:Language; D008037:Linguistics; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D008606:Mental Processes; D013647:Task Performance and Analysis