Transcranial direct current stimulation

Friday, January 30th, 2009

Transcranial direct current stimulation (tDCS) sounds like a “futuristic” idea from the 1930s:

In this case, electrodes attached to the person’s head run a current directly through the brain; the location of the electrodes can target the current to specific areas of the brain. At the cellular level, these currents are extremely weak, but they’re thought to reduce the voltage barrier needed for a nerve to fire, essentially enhancing normal activity.

A new Proceedings of the National Academies of Science paper describes how stimulating the primary motor cortex can help people learn motor skills:

By the end of day one, those who had an anode placed near the primary motor cortex were already pulling away from their peers (a cathode had no effect), and had opened up a large and significant gap by the end of day five. As expected, stopping the training at day five resulted in a gradual decline of the skills over time. Because the two sets of subjects showed declines of roughly the same rate, the gap that opened up during training wound persisting to at least 85 days after the training sessions ended.

The authors also looked into whether the [effect] of tDCS comes from the formation of or consolidation of the training by comparing the gains within a day to the retention of skills between days, which they called online and offline training. Overall, the differences in online gains between the two groups weren’t statistically significant. Between days, however, the control group was prone to forget some of the skills they had developed; in contrast, those receiving the current actually came back the next day in better shape than they’d left the day before.

(Hat tip to Al Fin.)

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