Very little is known about how TDCS works. Scientists theorize that the mild current primes the neurons for action but does not trigger the voltage spikes that neurons use to communicate. "Presumably, it is polarizing neurons and making them more or less likely to respond to inputs,"

Cognitive enhancement with drugs such as Ritalin, prescribed for attention deficit disorder, is already widespread, of course. A survey published online at Nature in April found that one in five respondents, most of whom were academics and scientists, reported using such drugs for nonmedical use. Electrical stimulation may prove even easier to access. "Half the people in this room could build this type of device with parts from RadioShack," Wassermann told a crowd at a neurotechnology conference in Cleveland last week.

I would need about 50,000 volts....