Using interleaved transcranial magnetic stimulation/functional magnetic resonance imaging (fMRI) and dynamic causal modeling to understand the discrete circuit specific changes of medications: Lamotrigine and valproic acid changes in motor or prefrontal effective connectivity

Xingbao Li, Charles H. Large, Raffaella Ricci, Joseph J. Taylor, Ziad Nahas, Daryl E. Bohning, Paul Morgan, Mark S. George

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The purpose of this study was to use interleaved transcranial magnetic stimulation/functional magnetic resonance imaging (TMS/fMRI) to investigate the effects of lamotrigine (LTG) and valproic acid (VPA) on effective connectivity within motor and corticolimbic circuits. In this randomized, double-blind, crossover trial, 30 healthy volunteers received either drug or placebo 3.5. h prior to interleaved TMS/fMRI. We utilized dynamic causal modeling (DCM) to assess changes in the endogenous effective connectivity of bidirectional networks in the motor-sensory system and corticolimbic circuit. Results indicate that both LTG and VPA have network-specific effects. When TMS was applied over the motor cortex, both LTG and VPA reduced TMS-specific effective connectivity between primary motor (M1) and pre-motor cortex (PMd), and between M1 and the supplementary area motor (SMA). When TMS was applied over prefrontal cortex, however, LTG alone increased TMS-specific effective connectivity between the left dorsolateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC). In summary, LTG and VPA both inhibited effective connectivity in motor circuits, but LTG alone increased effective connectivity in prefrontal circuits. These results suggest that interleaved TMS/fMRI can assess region- and circuit-specific effects of medications or interventions.

Original languageEnglish (US)
Pages (from-to)141-148
Number of pages8
JournalPsychiatry Research - Neuroimaging
Volume194
Issue number2
DOIs
StatePublished - Nov 30 2011

Keywords

  • Dynamic causal modeling
  • Lamotrigine
  • Network
  • Neuroimaging
  • Transcranial magnetic stimulation
  • Valproic acid

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