10. 10. 2010
Functional neuroimaging studies provide evidence for medial frontal cortical hyperactivation in obsessive-compulsive disorder (OCD). Quantitative electroencephalographic (EEG) studies confirmed abnormal activity over frontal regions in OCD, however, there is only limited knowledge about its generators. The goal of this study was to assess the activity of intracortical EEG sources in patients with OCD. We compared resting EEG from 50 OCD patients and 50 matched controls using standardized low-resolution tomography (sLORETA) and independent component analysis (ICA). Data were analyzed with 1 Hz frequency resolution. ICA was used to separate 7 independent components from the control group data. The resulting weights and norms served to derive the same components from the OCD group and to compare their power with controls. In OCD, sLORETA indicated low-frequency power excess (2 – 6 Hz) in the medial frontal cortex. ICA comparison showed increased low-frequency power in a component reflecting the activity of subgenual anterior cingulate, adjacent limbic structures and to a lesser extent also of lateral frontal cortex. Both the voxel-based (sLORETA) and source separation (ICA) approach provide evidence for medial frontal hyperactivation in OCD. Our study is the first to use normative ICA in a clinical sample and indicates its potential utility as a diagnostic tool. The findings provide consistent results based on EEG source localization in OCD and are of practical interest for therapeutic interventions such as neurofeedback.
Acknowledgement:
This work was supported by the grant NS9751-3/2008 provided by the Ministry of Health of the Czech Republic.