Neuroplasticity is the ability of the brain to constantly change and thereby learn something new or adapt to different conditions. This is not only essential for memory, but also for the recovery after brain injuries. Pathological changes in neuroplasticity also play a role in neurological and psychiatric diseases. This is why research into processes of neuroplasticity is so important.
And this is where non-invasive brain stimulation comes in. With the help of electrical or electromagnetic impulses, neuroplasticity of the brain can be influenced and analyzed – without the need for surgery. Transcranial direct current stimulation (tDCS) is one of such non-invasive brain stimulation techniques which uses weak direct currents to alter neuroplasticity. The influence of this technique depends on the stimulation parameters, such as duration and current intensity, but parameter-effect relations are not linear in each case. It is therefore necessary to study the stimulation parameters and their effects on neuroplasticity systematically in order to improve the application protocols for brain stimulation. Until now, there are still few studies on stimulation parameters with higher current intensity and longer duration.
In a recent IfADo study, Desmond Agboada and his colleagues examined the neuroplasticity of 16 young participants. Participants received ten sessions made up of nine active stimulation sessions with different current intensities (1, 2, or 3 mA), durations (15, 20, or 30 minutes), and a control (sham) condition.
The results: Basically, each of the 9 active conditions led to enhanced excitability of the stimulated brain area compared to the control (sham) condition. However, there were no or only very small differences between the three durations and intensities of stimulation tested. Only in two active conditions did a higher current intensity tend to have an effect lasting for more than few hours (3 mA-20 min and 2 mA-20 min conditions) when compared with sham. These results might be used to adapt the stimulation protocols for experimental and clinical use.
The study was recently published in the journal ‘Scientific Reports’. This work was supported by a research grant from the German Federal Ministry of Research and Education (BMBF; GCBS grant 01EE1501, TRAINSTIM grant 01GQ1424E), and publication was made possible with the Leibniz Open Access Fund.
Agboada D, Mosayebi Samani M, Jamil A, Kuo MF, Nitsche MA: Expanding the parameter space of anodal transcranial direct current stimulation of the primary motor cortex. Sci Rep 9(1): 18185 (2019). (11 pp) http://dx.doi.org/10.1038/s41598-019-54621-0