Researchers at the National Institutes of Health have developed a way to cognitively enhance the brain’s activity by placing electrodes directly on the surface of the scalp, using transcranial direct current stimulation (tDCS).

The electrodes are damp sponges about 4 square centimeters in area that deliver a current of a few milliamps. Neurons underneath the positively charged electrode are stimulated to fire more frequently in response to normal incoming signals.

Researchers have shown that tDCS can be used as a cognitive enhancer to help people learn a task involving precise hand movements and as a way to boost mathematical skills. The technique is also being investigated as a treatment for depression, chronic pain and migraine.