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 language | English (US) |
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Pages (from-to) | 141-148 |
Number of pages | 8 |
Journal | Psychiatry Research - Neuroimaging |
Volume | 194 |
Issue number | 2 |
DOIs | |
State | Published - Nov 30 2011 |
Bibliographical note
Funding Information:This study was funded primarily by an unrestricted research grant from GlaxoSmithKline to Dr. George, as well as from Center for Advanced Imaging Research and Brain Stimulation Laboratory infrastructure and resources. CHL is a full-time employee of GlaxoSmithKline S.p.A. None of the other authors has equity or financial conflicts. Drs. Li and George had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Presented in abstract form at the annual meeting of American College of Neuropsychopharmacology, Hollywood, FL, Dec 14, 2006 and the annual meeting of the Society of Biological Psychiatry, San Diego, CA, May 21, 2007.
Keywords
- Dynamic causal modeling
- Lamotrigine
- Network
- Neuroimaging
- Transcranial magnetic stimulation
- Valproic acid