Modulation of dopaminergic transmission and brain activity by frontotemporal tDCS: A multimodal PET-MR imaging study
Clara Fonteneau, Inès Mérida, Jérôme Redouté, Frédéric Haesebaert, Sophie Lancelot, Nicolas Costes, Marine Mondino, Jérôme Brunelin
Abstract
Background Transcranial Direct Current Stimulation (tDCS) is a promising noninvasive intervention for schizophrenia, particularly when applied using a frontotemporal montage. Although significant clinical benefits have been reported, the variability in individual responses underscores the need for a more comprehensive understanding of its underlying neurophysiological mechanisms. Here, we used a simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) approach to investigate the effects of frontotemporal tDCS on dopamine transmission, cerebral perfusion, and white matter microstructural integrity in healthy individuals. Methods In a double-blind, randomized, two-arm, parallel group study, 30 healthy volunteers were randomly allocated to receive a single session of either active (n=15) or sham (n=15) frontotemporal tDCS. The stimulation session was delivered during simultaneous multimodal PET-MR imaging, which combined PET with the [ 11 C]raclopride radiotracer, Arterial Spin Labeling (ASL), and Diffusion Weighted Imaging (DWI). Results PET [ 11 C]raclopride analysis revealed a significant reduction in Non-Displaceable Binding Potential in the left executive striatal subregion 15 minutes after tDCS in the active group, compared to both baseline and the sham group. This finding suggests that frontotemporal tDCS may induce an increase in dopamine release. ASL analysis showed that active tDCS may reduce cerebral blood flow in the precuneus compared to sham stimulation. No significant effects of tDCS were observed on white matter microstructural integrity. Conclusion This study provides new insights into the neurophysiological mechanisms of frontotemporal tDCS, paving the way for the optimization of therapeutic strategies for patients with dysregulated cortico-subcortical dopamine systems.