Transcranial direct current stimulation (TDCS) could improve memory in participants asked to learn and then recall a list of 12 words. The effect was significant in the early learning stages: in the first few trials, in which participants were given the same list over and over again, people in the treatment group could remember more words. But the learning curve for those working without the device quickly caught up to the zapped learners.
This conclusion of a recent research on TDCS published on Technology Review: Want to Enhance Your Brain Power?
At first the encoding of of the words is better in subjects treated with TDCS. Improving the encoding by training this test catches up after a while. The treatment with TDCS was done prior to the learning task, what if it was done during the test?
What is TDCS?
The device is simple: a nine-volt battery that's been approved by the Food and Drug Administration for delivering drugs across the skin is connected to large flat sponges that are moistened and then applied to the head. It delivers a gentle 2 to 2.5 milliamps of current spread over a 20 to 50 square millimeter area of the scalp for up to 15 minutes. Little of that current actually reaches the brain--about half is shunted away from the target area, and the other half quickly dissipates as it gets farther from the scalp. The target in this research was the part of the brain known as the dorsolateral prefrontal cortex, a brain area involved in higher-level organization and planning, as well as in working memory. Because activity in this region has been shown in previous imaging studies to predict an individual's ability to recall information, the idea is that giving it an electrical boost will enhance memory function.
TDCS is something completely different than ECT. It is not used to elicit a general seizure, it doesn't require anesthesia and it is not tested properly for the treatment of depression.
Side-effects of TDCS
In the afore mentioned article only a slight dizziness was reported as side effect. In a upcoming publication in Brain Stimulation other side-effects are reported with TDCS. In 4 out of 4 patients treated with a higher dose (2mAmpere) during each active TDCS session with over 20 minutes (15-second ramp in and ramp out each) of stimulation on 5 days per week during a 2-week period, skin lesions were present. Generally, these lesions occurred after the fourth or fifth DC-stimulation, showed stable superficial extensions during further tDCS, and healed without scars about 1-3 weeks after the end of tDCS treatment.
The occurrence of lesions may depend on the intensity and duration of TDCS as well as on the impedance between electrode and skin.
Thanks Neuromod Blog
Related post on this blog: tDCS electrifying?
PALM, U., KEESER, D., SCHILLER, C., FINTESCU, Z., REISINGER, E., PADBERG, F., NITSCHE, M. (2008). Skin lesions after treatment with transcranial direct current stimulation (tDCS). Brain Stimulation DOI: 10.1016/j.brs.2008.04.003