Event Abstract

Dorsolateral prefrontal cortex network properties are altered in schizophrenia: a TMS-EEG study

  • 1 Monash University, Monash Alfred Psychiatry Research Centre, Australia
  • 2 Centre for Addiction and Mental Health, University of Toronto, Temerty Centre for Therapeutic Brain Intervention, Canada

Background: Dysfunctional dorsolateral prefrontal cortex (DLPFC) activation during working memory is a consistent finding in schizophrenia (SCZ). However, determining whether these deficits reflect aberrant DLPFC network properties or impaired attention, motivation or sensory integration has proven difficult. The aim of this study was to assess DLPFC function evoked by non-invasive transcranial magnetic stimulation (TMS) and working memory performance in people with and without SCZ.
Methods: 19 volutneers with SCZ and 20 healthy controls received single TMS pulses to the left DLPFC while electroencephalography was recorded. Several indices of TMS-evoked cortical function were measured at the DLPFC and across the scalp including TMS-evoked cortical potentials such as the N100 (a putative marker of cortical inhibition) and TMS-evoked cortical oscillations. Working memory was assessed using the Sternberg letter recognition task with 5 and 7 letters.
Results: The N100 slope and amplitude were reduced over the DLPFC of SCZ participants compared with controls, whereas latter TMS-evoked potentials (P180) were increased. TMS-evoked oscillations (13-45 Hz) at the DLPFC were also reduced, as was propagation of gamma (31-45 Hz) oscillations to left parietal cortex and upper beta (21-30 Hz) oscillations to contralateral DLPFC. SCZ participants with low working memory capacity displayed significantly reduced TMS-evoked gamma oscillations over DLPFC compared with other SCZ participants and controls.
Discussion: Intrinsic DLPFC network properties such as cortical inhibition and the ability to entrain high frequency oscillations in local and distant cortical regions are altered in SCZ. A reduced capability of the DLPFC to generate gamma oscillations may contribute to SCZ-related working memory deficits.

Keywords: Schizophrenia, working memory, Transcranial Magnetic Stimulation, gamma oscillations, plasticity

Conference: ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.

Presentation Type: Oral

Topic: Executive Processes

Citation: Rogasch N, Rajji T, Tran LC, Bailey N, Fitzgibbon BM, Daskalakis ZJ and Fitzgerald P (2013). Dorsolateral prefrontal cortex network properties are altered in schizophrenia: a TMS-EEG study. Conference Abstract: ACNS-2013 Australasian Cognitive Neuroscience Society Conference. doi: 10.3389/conf.fnhum.2013.212.00158

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Received: 15 Oct 2013; Published Online: 25 Nov 2013.

* Correspondence: Mr. Nigel Rogasch, Monash University, Monash Alfred Psychiatry Research Centre, Melbourne, Victoria, 3004, Australia, nigel.rogasch@monash.edu