Somatosensory electrical stimulation produces motor learning and synaptic plasticity

Natural aging and neurological disorders reduce the quality of movements and the ability to learn or relearn skills. Exploiting the adaptability of the brain by low-intensity stimulation of nerves in the arm can produce the learning of a complex skill that requires accurate wrist movements. These effects are observed not only in healthy individuals, but also in patient groups such as stroke and dystonia. To maximize the effects, it is important to have a complete understanding of how such stimulation improves the quality of movements. To gain more insights into the mechanisms underlying the effects of low-intensity stimulation on the quality of movements, the researchers developed a model predicting which brain areas and connections are involved in the effects of stimulation. In 100 healthy young adults, the researchers evaluated if 20 minutes of low-intensity stimulation of nerves in the arm improved the accuracy of movements and how long the effects lasted after the stimulation. Second, the researchers examined whether increased brain activity and connectivity was related to the increased accuracy of movements. The results showed that low-intensity stimulation induced the learning of a complex task which lasted up to seven days after the stimulation. Next, the results showed that improvements in task performance were related to elevated levels of brain activity and increased connectivity between different brain areas. In conclusion, low-intensity stimulation can be one way to counteract the negative consequences of natural aging and neurological disorders by improving movement accuracy through changes in brain activity and connectivity.