tDCS-induced modulation of GABA concentration and dopamine release in the human brain: A combination study of magnetic resonance spectroscopy and positron emission tomography

Abstract

Background: Transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC) hypothetically modulates cognitive functions by facilitating or inhibiting neuronal activities chiefly in the cerebral cortex. The effect of tDCS in the deeper brain region, the basal ganglia-cortical circuit, remains unknown.Objective: To investigate the interaction between g-aminobutyric acid (GABA) concentrations and dopamine release following tDCS. Method: This study used a randomized, placebo-controlled, double-blind, crossover design. Seventeen healthy male subjects underwent active and sham tDCS (13 min twice at an interval of 20 min) with the anode placed at the left DLPFC and the cathode at the right DLPFC, followed by examinations with [ 11 C]raclopride positron emission topography (PET) and GABA-magnetic resonance spectroscopy (MRS). MRS voxels were set in the left DLPFC and bilateral striata. Paired t-tests and regression analyses were performed for PET and MRS parameters. Results: MRS data analyses showed elevations in GABA in the left striatum along with moderate reductions in the right striatum and the left DLPFC after active tDCS. PET data analyses showed that reductions in [ 11 C]-raclopride binding potentials (increase in dopamine release) in the right striatum were inversely correlated with those in the left striatum after active tDCS. GABA reductions in the left DLPFC positively correlated with elevations in GABA in the left striatum and with increases in right striatal dopamine release and negatively correlated with increases in left striatal dopamine release. Conclusion:The present results suggest that tDCS to the DLPFC modulates dopamine-GABA functions in the basal ganglia-cortical circuit.

The effect of transcranial direct current stimulation of dorsolateral prefrontal cortex on performing a sequential dual task: a randomized experimental study

“…This effect modulates cognitive functions. The last finding suggested tDCS also has an effect on deeper brain regions, for example, tDCS to the DLPFC modulates dopamine-GABA functions in the basal ganglia-cortical circuit (Bunai et al, 2021).…”

Transcranial Direct Current Stimulation on Different Targets to Modulate Cortical Activity and Dual-Task Walking in Individuals With Parkinson’s Disease: A Double Blinded Randomized Controlled Trial

“…A previous study also reported that dopaminergic treatment could prolong SP duration in patients with PD and suggested that SP may be modulated by the dopamine system (Nakashima et al, 1995). Furthermore, the recent study showed tDCS-induced dopamine release and GABA changes, which contributes to the phenomenon of SP (Bunai et al, 2021). Taking together, the beneficial motor effects of DLPFC tDCS may be related to dopamine release, therefore modulating the cortical inhibition in individuals with PD.…”

Non-Invasive Brain Stimulation Modulates GABAergic Activity In Neurofibromatosis 1

“…The prefrontal cortex is heavily regulated by dopamine and stimulation of frontal cortex may lead to an increase in extracellular dopamine concentrations (44). A recently published study demonstrated that stimulation of left DLPFC in healthy populations is associated with reduction of GABA in left DLPFC but also modulation of both GABA and dopamine in the striatum, demonstrating the effect of atDCS beyond the targeted cortical structures (45). Given the importance of corticostriatal activity in NF1 and other neuropsychiatric conditions, it will be important to determine in future studies whether stimulation of DLPFC has a modulatory effect on the neurotransmitters in the striatum.…”