Synaptic remapping by electrical stimulation after stroke. (Credit: DGIST)

A new electrical brain stimulation technique could improve the recovery of patients from strokes. The technique uses less energy and has fewer side effects than existing methods. The researchers developed a method called subthreshold electrical stimulation, through which a low-power electrical signal can be applied to neurons at a synapse — a junction between two neurons where electric nerve impulses are transmitted.

The physical experiment involved the subthreshold electrical stimulation of post-synaptic neurons in rats’ brains. At the same time, the rats were running on a wheel, which naturally stimulated the pre-synaptic neurons. This process was performed twice a day for 16 days. At the end of the treatment, they monitored the rats’ behavior and tested for the presence of proteins that signify neuronal recovery.

The results showed that neither exercise nor subthreshold electrical stimulation alone were able to initiate a nerve impulse at the synapse. However, when they occurred simultaneously, the neurons reached the threshold required to fire a signal. The researchers found that the stimulated brain regions contained higher levels of specific neural proteins, indicating that neural reconstruction had taken place. The results imply that subthreshold electrical stimulation, when combined with motor training early in rehabilitation, may strengthen connections between brain regions and aid motor recovery.

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