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Updated: Jun 15, 2026
A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy
Published on: November 13, 2016
Interleaved transcranial magnetic stimulation and fMRI suggests that lamotrigine and valproic acid have different
Xingbao Li1, Raffaella Ricci, Charles H Large
1Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, 502N, 67 President St, Charleston, SC 29425, USA. lixi@musc.edu
Rationale:
Combined transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) can be used to study anticonvulsant drugs. A previous study showed that lamotrigine (LTG) inhibited brain activation induced when TMS was applied over motor cortex, whereas it increased activation induced by TMS applied over prefrontal cortex.
Objectives:
The present double-blind, placebo-controlled, crossover study in 30 healthy subjects again combined TMS and fMRI to test whether the effects seen previously with LTG would be confirmed and to compare these with a second anticonvulsant drug, valproic acid (VPA).
Results:
Statistical parametric mapping analysis showed that both LTG and VPA, compared to placebo, inhibited TMS-induced activation of the motor cortex. In contrast, when TMS was applied over prefrontal cortex, LTG increased the activation of limbic regions, confirming previous results; VPA had no effect.
Conclusion:
We conclude that LTG and VPA have similar inhibitory effects on motor circuits, but differing effects on the prefrontal corticolimbic system. The study demonstrates that a combination of TMS and fMRI techniques may be useful in the study of the effects of neuroactive drugs on specific brain circuits.
