Dissociation between MEG alpha modulation and performance accuracy on visual working memory task in obsessive compulsive disorder

  • Ciesielski K
  • Hämäläinen M
  • Geller D
 et al. 
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Oscillatory brain activity in the alpha band (8-13 Hz) is modulated by cognitive events. Such modulation is reflected in a decrease of alpha (event-related desynchronization; ERD) with high cognitive load, or an increase (event-related synchronization) with low cognitive demand or with active inhibition of distractors. We used magnetoencephalography to investigate the pattern of prefrontal and parieto-occipital alpha modulation related to two variants of visual working memory task (delayed matching-to-sample) with and without a distractor. We tested nonmedicated, nondepressed patients suffering obsessive-compulsive disorder (OCD), and pair-matched healthy controls. The level of event-related alpha as a function of time was estimated using the temporal-spectral evolution technique. The results in OCD patients indicated: (1) a lower level of prestimulus (reference) alpha when compared to controls, (2) a task-phase specific reduction in event-related alpha ERD in particular for delayed matching-to-sample task with distractor, (3) no significant correlations between the pattern of modulation in prefrontal and parietal-occipital alpha oscillatory activity. Despite showing an abnormally low alpha modulation, the OCD patients' performance accuracy was normal. The results suggest a relationship of alpha oscillations and the underlying thalamocortical network to etiology of OCD and an involvement of a compensatory mechanism related to effortful inhibition of extrinsic and intrinsic interference.

Author-supplied keywords

  • Event-related alpha modulation
  • Event-related desynchronization (ERD)
  • Event-related synchronization (ERS)
  • Limited resources inhibitory control
  • Magnetoencephalography
  • Temporal-spectral evolution technique (TSE)
  • Visual-spatial working memory task

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  • Kristina T. Ciesielski

  • Matti S. Hämäläinen

  • Daniel A. Geller

  • Sabine Wilhelm

  • Timothy E. Goldsmith

  • Seppo P. Ahlfors

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