Document Type
Journal Article
Publication Title
Brain Stimulation
Volume
17
Issue
3
First Page
553
Last Page
560
PubMed ID
38604563
Publisher
Elsevier
School
School of Medical and Health Sciences
RAS ID
70307
Abstract
Non-invasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS), are popular methods for inducing neuroplastic changes to alter cognition and behaviour. One challenge for the field is to optimise stimulation protocols to maximise benefits. For this to happen, we need a better understanding of how stimulation modulates cortical functioning/behaviour. To date, there is increasing evidence for a dose-response relationship between tDCS and brain excitability, however how this relates to behaviour is not well understood. Even less is known about the neurochemical mechanisms which may drive the dose-response relationship between stimulation intensities and behaviour. Here, we examine the effect of three different tDCS stimulation intensities (1 mA, 2 mA, 4 mA anodal motor cortex tDCS) administered during the explicit learning of motor sequences. Further, to assess the role of dopamine in the dose-response relationship between tDCS intensities and behaviour, we examined how pharmacologically increasing dopamine availability, via 100 mg of levodopa, modulated the effect of stimulation on learning. In the absence of levodopa, we found that 4 mA tDCS improved and 1 mA tDCS impaired acquisition of motor sequences relative to sham stimulation. Conversely, levodopa reversed the beneficial effect of 4 mA tDCS. This effect of levodopa was no longer evident at the 48-h follow-up, consistent with previous work characterising the persistence of neuroplastic changes in the motor cortex resulting from combining levodopa with tDCS. These results provide the first direct evidence for a role of dopamine in the intensity-dependent effects of tDCS on behaviour.
DOI
10.1016/j.brs.2024.03.015
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Leow, L. A., Jiang, J., Bowers, S., Zhang, Y., Dux, P. E., & Filmer, H. L. (2024). Intensity-dependent effects of tDCS on motor learning are related to dopamine. Brain Stimulation, 17(3), 553-560. https://doi.org/10.1016/j.brs.2024.03.015