Lasting effects of transcranial direct current stimulation on the inducibility of synaptic plasticity by paired-associative stimulation in humans.
Stefan Vestring, Elias Wolf, Johanna Dinkelacker and 8 others
PMID 39289746WHAT IT FOUND
A single 20-minute session of anodal tDCS over the motor cortex enhanced brain plasticity responses six hours later.
Splitting the same total stimulation time into multiple shorter blocks failed to produce this benefit, suggesting continuous duration matters more than repetition for lasting effects.
Key findings
01One continuous 20-minute block of anodal tDCS significantly increased motor cortex plasticity six hours later compared to sham stimulation.
02Splitting the stimulation into multiple shorter blocks (sequential tDCS) did not improve plasticity outcomes compared to sham, despite matching total stimulation duration.
03Reversing polarity during the interval between stimulation blocks suppressed the expected plasticity response.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study was conducted on healthy young adults (mean age 24.3 years), so the results may not translate to older patients or those with neurological conditions where plasticity mechanisms are already altered. The electrode placement used a non-standard parietal return electrode, which differs from typical clinical montages and may affect how the current flows through the brain. The study measured neurophysiological changes (MEPs) rather than functional clinical improvements like motor skill learning or recovery. The sample size was small (36 participants total, 12 per group), and the analysis of specific subgroup responses relied on very small numbers (7-8 participants).
Declared interests
The study was funded by Universitätsklinikum Freiburg. No other conflicts of interest were declared.
The easy way to misread this
Do not assume that splitting tDCS into multiple shorter blocks is a valid strategy to enhance effects. The study found that only the single continuous 20-minute block improved plasticity six hours later, while fragmented protocols showed no benefit over sham.