tDCS electrode placement



By Jared Cooney Horvath15-years ago, a group of German researchers decided to revive the ancient practice of using electricity to effect physiologic change in the human body. Using modern equipment and safety measures, this group reported that they were able to alternately up- and down-regulate neuronal firing patterns in the brain simply by sending a weak electric current between two electrodes placed on the scalp 1 Today, this technique is called Transcranial Direct Current Stimulation (tDCS) and over 1,400 scientific articles (calculated by combining non-replicated articles from a joint PubMed, ISI Web of Science, and Google Scholar search using the keywords “Transcranial Direct Current Stimulation”: October 15, 2014) have been published suggesting that passing an arguably innocuous amount of electricity through the brain of a healthy individual can improve his/her memory, learning, attention, inhibitory control, linguistic function, etc. In parallel with these findings (often fueled by the researchers themselves), the public hype surrounding tDCS has grown to impressive proportions: in fact, in the last year alone, stories about this device and its ability to improve cognition and behavior have appeared in popular news outlets ranging from the BBC 2 to Wired 3 to The Wall Street Journal 4 Doubtless fueled by this hype, there are currently 3 tDCS devices (and 2 in development) available for public purchase without the need of a medical prescription. In fact, as you read this, there are likely hundreds of people around the world trying to ‘boost’ their own brain power using these unregulated devices.Unfortunately, a series of quantitative reviews undertaken by this grouphas revealed that tDCS does not generate a significant or reliable effect on neurophysiology, cognition, or behavior. When combined, the last 15-years of data strongly suggest that either, A) tDCS does not have an actual effect, or B) tDCS generates an effect that we can neither explain, elucidate, nor predict.This raises an incredibly important question: what are the responsibilities of a researcher when data he/she once publicized comes under question? More specifically, the tDCS data makes it quite clear that we do not have a solid handle on the mechanisms or effects of this device. As such, what role do we (researchers) play in ensuring the public are made aware of these developments and protected from possible neural injury or, at the least, economic waste?It seems acceptable (almost expected) that researchers will publicize positive, potentially beneficial results – especially with regards to health and well-being. But, as has recently been reported in areas of research beyond tDCS, the number of retractions and amendments made to scientific articles is growing wildly. Unfortunately, the public is rarely made aware of these changes, leaving them expecting results utilizing paradigms that may no longer be viable or accepted in the scientific cannon.One reason we (researchers) chose to avoid hyping our negative results is obvious: research is a very messy endeavor and there’s always danger in letting the customer see inside the kitchen. It’s an intelligent, safe decision to put only the most exciting, interesting, and applicable work forward for public scrutiny. However, as is becoming clear in articles like those cited above, more and more people are becoming aware of the fact that science is not the ideal, straightforward endeavor it’s often claimed to be - in fact, it is rife with the same unpredictable changes and sudden shifts that define all human endeavors. I fear if we continue to ignore the uncertain, vacillatory nature of our profession in the public and continue to only hype ‘success’, we will quickly lose the faith of the very people we are trying to inspire.It will certainly be interesting to see how the most prominent voices in the field chose to respond to the changing, increasingly less-certain landscape of tDCS. Is it safe to let the public know that we may have jumped-the-gun, and that we require more time and basic research before we can determine whether or not this is an efficacious tool? I believe that, although this type of message may damage our reputation in the short-term, not being honest with the public and trying to keep controversies ‘in-house’ will only serve to damage our reputation far more in the long-term.Horvath, J. (2015). When the Hype Doesn’t Pan Out: On Sharing the Highs-and-Lows of Research with the Public. The Neuroethics Blog. Retrieved on , from http://www.theneuroethicsblog.com/2015/02/when-hype-doesnt-pan-out-on-sharing.html