When most of us think of electricity and the brain together, we generally visualize what is known as electroconvulsive therapy (ECT) with an image of a man’s face in gruesome pain. Thanks to One Flew Over the Cuckoo’s Nest for that! But, recently, there has been a revival of interest in a somewhat subdued version of ECT referred to as transcranial electric stimulation (tES) encompassing direct current (tDCS), alternating current (tACS) and random noise (tRNS) stimulation. One key difference between these methods and ECT is the intensity of current being used. Whereas tES techniques only use a few milliamperes of current, ECT often uses hundreds of milliamperes ensuring a much more vigorous manipulation of the brain state. tES also comes in at a low cost and with negligible discomfort or side effects. So the idea of someone just hooking their heads up to a battery and manipulating their brain activity without risking too much might just be a little more close to reality than we would expect.
Besides its use in clinical therapy (depression, chronic pain, stroke recovery and what not; just search for “transcranial electric stimulation” in ClincialTrials.gov — we can also expand our imagination and think of some other fun applications. For instance, why not stimulate the pitcher of your base ball team for some extra speed in his pitches? Or, read up your text book and go to bed with your head hooked up to the stimulator, accelerating memory consolidation during sleep. How about training athletes and military personnel to develop faster reaction times and better visuomotor coordination by stimulation? How about stimulating the US senators before crucial meetings to enhance their critical thinking or planning capabilities? Recent experimental results do render some of these possibilities feasible. For instance, Lisa Marshall and colleagues has recently reported that tDCS during sleep improves declarative memory . Colleen Dockery and colleagues have provided evidence towards enhancement of planning ability by tDCS . Improvement of motor learning skills, reactions times, numerical capabilities and other tasks has also been reported (for review, see ).
Everything so far seems just great! But there are also reasons why you should think twice before you subscribe to these tools. First, although there is a plethora of reports of behavioral effects of tES, the mechanisms of actions of tES is pretty much unknown and existing theories can be categorized as mere speculations. Second, if there are adverse chronic effects (which requires objective longitudinal studies); we probably are better off harnessing our natural brain power rather than messing it up with unknown electrical manipulations. Third, what if tES is nothing but a placebo? There isn’t a definitive answer to the last question yet. Hence it remains important for us to remain skeptical about the applications of tES. But at the same time, given the exciting possibilities, we should invest resources and encourage scientists to study the effects of external electric fields on our brains. If we play the cards right, we might just be a decade away from going to radio shack and ordering the $5 Brain Recharger Kit!
1. Marshall L, Mölle M, Hallschmid M, & Born J (2004). Transcranial direct current stimulation during sleep improves declarative memory. The Journal of neuroscience : the official journal of the Society for Neuroscience, 24 (44), 9985-92 PMID: 15525784
2. Dockery CA, Hueckel-Weng R, Birbaumer N, & Plewnia C (2009). Enhancement of planning ability by transcranial direct current stimulation. The Journal of neuroscience : the official journal of the Society for Neuroscience, 29 (22), 7271-7 PMID: 19494149
3. Utz KS, Dimova V, Oppenländer K, & Kerkhoff G (2010). Electrified minds: transcranial direct current stimulation (tDCS) and galvanic vestibular stimulation (GVS) as methods of non-invasive brain stimulation in neuropsychology–a review of current data and future implications. Neuropsychologia, 48 (10), 2789-810 PMID: 20542047