Talk:Transcranial direct-current stimulation/Archive 1

Clear plagiarism and/or marketing language
Multiple sentences in the "Discovery" section are lifted directly from a page that markets a particular tDCS device: http://www.trans-cranial.com/howitworks. They either copied it from wikipedia or (more likely) they copied themselves to pad the article. Not sure what to do about this. I'm deleting a couple of the offending sentences. superbatfish (talk) 19:16, 6 November 2012 (UTC)
 * Wikiblame is useful to find when content was added and by whom. If all the content was added at the same time or by the same editor, it should probably be removed.
 * Looks like it was by one editor, if I've identified it correctly:  --Ronz (talk) 19:52, 6 November 2012 (UTC)
 * I don't have time to look into this in any detail. I'm not clear that I've found the appropriate edits, nor what may have been copied. --Ronz (talk) 20:05, 6 November 2012 (UTC)

Mechanisms of action
The actions on the excitability of neurones will depend upon the orientation of neurones within the electrical field. I would actually expect cortical pyramidal cells (probably the main class targeted) near the anode to be excited, but these predictions are hard to make. Does anybody actually know of any real electrophysiological data on this question?

The description of which electrode is excitatory in incompatible with the hypothesized regulation of hyperactivity.

All the mechanisitic speculation about LTP, LTD etc seems just that - VERY speculative.

The control of sham stimulation seems imperfect. Even if subjects have no consciousness of the continued stimulation, presumably nerve endings in the scalp are still potentially activated. Has anybody performed a control with a local anaesthetic? — Preceding unsigned comment added by 217.109.152.80 (talk) 09:45, 4 April 2013 (UTC)

Overly broad claims
This is a new form of treatment supported by a small foundation in published literature. This article reads like promotional pamphlets for a TDCS clinic. Disgraceful! 69.108.166.39 (talk) 22:40, 27 February 2013 (UTC)

28 references isn't a "a small foundation in published literature". The above reaction ("Disgraceful") is over the top in my view. Fletcherbrian (talk) 17:09, 31 October 2013 (UTC)

28 references is fine, but the article is still written like an advertisement, and many people seeking genuine information about tDCS on Wikipedia may disregard the article due to the way it is written. So yes, disgraceful. — Preceding unsigned comment added by 174.113.164.82 (talk) 05:18, 21 November 2013 (UTC)

Safety
The device shouldn't have a battery greater than 6 volts. Burning of the skin (at the least) is a risk. I've had burns on my skin using a 9 volt PP3 battery despite limiting the current to 2 mA. I would not like to think that a similar burning took place in my internal organs - particularly my brain.Fletcherbrian (talk) 14:00, 18 December 2013 (UTC)

The edits on safety have been deleted - I have reinstated them. There is plenty of empirical evidence that using 9 volts DC on the body is not safe. If required I will post the necessary links, but Wikipedians could be in big trouble if someone killed themselves using a device that say, stopped their heart, because of a lack of a warning on here. Fletcherbrian (talk) 19:23, 15 January 2014 (UTC)


 * I apologize if I am placing this is the wrong area, I am new to wikipedia. However, I am in the industry and I would have to completely disagree with your conclusion. In fact, using anything less than a 9V battery would be too small of current to overcome the resistance of the human head. So essentially if you tried to get 2mA using, say, a 6V battery, because of the limitation of the battery you may only be able to get 1.1mA. Additionally, if you received burns on your skin I would look at the specific circuitry that was used, along with the electrodes you used. In my opinion skin lesions are almost always tied to poor quality self-adhesive electrodes, or to sponge electrodes with too small a surface area. — Preceding unsigned comment added by The818Studios (talk • contribs) 03:29, 26 October 2014‎ (UTC)

Direction of current flow
The article reads: "The conventional current flows from the anode through the skull and brain to the cathode, creating a circuit." Gah. Electrons flow from the anode to the cathode, so the current actually flows from the cathode to the anode. Right??? — Preceding unsigned comment added by 68.84.104.254 (talk) 05:26, 28 January 2014 (UTC)

tDCS published as doubling effectiveness at some activities
The journal Nature has an informal article on tDCS where they describe research, Volunteers receiving 2 milliamps to the scalp (about one-five-hundredth the amount drawn by a 100-watt light bulb) showed twice as much improvement in the game after a short amount of training as those receiving one-twentieth the amount of current  — Preceding unsigned comment added by 68.185.2.34 (talk) 23:11, 17 April 2012 (UTC)
 * A 100 watt light bulb is equal to 100,000 milliamps. Therefore, 2 milliamps is not equal to one-five-hundreth of a 100-watt light bulb. 2 milliamps is about 50,000 times weaker than a 100-watt light bulb. 111.69.156.109 (talk) 23:36, 2 July 2013 (UTC)
 * Watts!=Amps. Light bulbs operate on more than 1 volt.

A 100 watt light bulb is NOT equal to 100,000 amps. Amps and watts are not the same. Watts are are amps multiplied by volts. Therefore the contribution immediately above is meaningless.

Fletcherbrian (talk) 16:56, 31 October 2013 (UTC)

Maybe I can shed some light on this.

Ohm's law: V=IR, where V=Voltage (volts), I=current (amps) and R=Resistance (ohms).

As mentioned by Fletcherbrian, P = VI, where P=power (watts).

Average (RMS) power-line voltage is around 120 volts in North America.

If you do the math, you'll find that a 100 watt bulb has current of 0.83 amp.

.83 amp = 830 ma.

830 ma / 2 ma = 416.

Therefore, a 2 ma tDCS current is 416 times weaker than a 100 watt light bulb's 830 ma current, and Nature's claim was close enough.

Please see http://www.ohmslawcalculator.com/ohms_law_calculator.php for a nice Ohm's law calculator.

~Peter Nau 05:13, 18 January 2015 (UTC)

potential resource
"Amping Up Brain Function: Transcranial Stimulation Shows Promise in Speeding Up Learning Electrical stimulation of subjects' brains is found to accelerate learning in military and civilian subjects, although researchers are yet wary of drawing larger conclusions about the mechanism" by R. Douglas Fields Scientific American November 25, 2011

99.181.147.68 (talk) 06:19, 4 January 2012 (UTC)

It's important to note that tDCS is NOT a cure all, however studies have shown that this is a promising technique. Equally important is to have an understanding of where the Anode (normally the red wire) and the Cathode (normally the black wire) have been placed in studies that correlate to various tested conditions. See below for some direction. (this site sells a tDCS device, but I am not suggesting you buy it. Use the site for the information referred to above as it may provide a better understanding of how electrode positioning affect specific brain functions)
 * TDCS Electrode Placement With Researched Case Studies Cited (linked) and Brain Maps — Preceding unsigned comment added by 98.220.234.91 (talk) 18:06, 23 March 2015 (UTC)

Old vs. new?
I don't understand why older scientific results are not allowed because newer exist. That edit doesn't make sense for me. It should be upon the reader to decide which source s/he uses. -- Amtiss, SNAFU ? 13:11, 27 January 2016 (UTC)
 * That journal has no impact factor. The newer source is not only newer but from a more respected journal. Doc James  (talk · contribs · email) 13:28, 27 January 2016 (UTC)
 * Might have been a better edit summary then... -- Amtiss, SNAFU ? 21:13, 27 January 2016 (UTC)

Weight of sources
There have been a couple of efforts here and earlier, here to contradict findings in recent reviews with older reviews or with commenting letters. Per WP:MEDRS we do not use older or weaker sources to undermine stronger, more recent ones. a POV tag was placed here but that seems to be an expression of the IP editor's dislike; it is not based on what reliable sources say.

That said, the lead was pretty weak in summarizing the research that has been done, so I improved the lead. Jytdog (talk) 12:24, 20 February 2016 (UTC)


 * Just came across two new meta-analysis papers on tDCS: http://www.ncbi.nlm.nih.gov/pubmed/26597929 and http://www.ncbi.nlm.nih.gov/pubmed/27054400. Would either of these merit changing the first paragraph of this wiki since they are newer reviews? Thanks! Bobjackleberry (talk) 15:33, 21 April 2016 (UTC)

"recent advances" and primary source
About this

....recent advances in neurotechnology allowing for in vivo assessment of brain electric activity during tDCS

We don't say anything is "recent" in WP per WP:RELTIME and you are introducing a primary source into the lead of an article making claims about health (how something works is a claim about health). In Wikipedia, claims about health need to be sourced per WP:MEDRS - reviews from the biomedical literature or statements by major health authorities.

I hear you on the stroke thing and while it is true - a lot of work has been done with TMS on helping stroke victims recover function from the earliest days - that is not one of the approved uses and I see how someone unfamiliar with the field would be confused. I fixed that.

The content you are interested in btw is discussed some in Transcranial_direct-current_stimulation. Jytdog (talk) 08:51, 14 June 2016 (UTC)

Dear Jytdog, thanks for clarifying that "recent" is not used in WP. Did not know that! Please find comments to the revisions (in bold) that I suggested to the tDCS article:

Transcranial direct current stimulation (tDCS) is a form of neurostimulation which uses constant, low current delivered to the brain area of interest via electrodes on the scalp.

This statement is not true, as it is unknown whether and where the brain is stimulated when attaching electrodes to the head and delivering very weak currents. 99% of the current flows over the skull, while 0.9% is shunted through the cerebral fluid and 0.1% of the currents actually enters the brain (but probably not immediately underneath the electrodes). Thus, stating that currents are delivered to the brain area of interest is misleading. Please also read the recent article in Science Magazine on this issue: http://www.sciencemag.org/news/2016/04/cadaver-study-casts-doubts-how-zapping-brain-may-boost-mood-relieve-pain

It was originally developed to help patients with brain injuries or psychiatric conditions like major depressive disorder. tDCS appears to be somewhat effective for treatment of depression. However, there is no good evidence that it is useful for cognitive enhancement in healthy people, memory deficits in Parkinson's disease and Alzheimer's disease, schizophrenia, pain, nor improving upper limb function after stroke.

This whole paragraph is misleading. First, tDCS was already applied by the ancient Egyptians using electric catfish and found its way into the literature about 200 years ago (http://www.aipass.org/files/TDCS_State%20of%20the%20art.pdf). It was certainly not purposefully "developed" to treat brain injuries. The underlying mechanisms of tDCS are widely unknown (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4368894/) as it was impossible to record brain oscillations (brain electric activity) during tDCS. However, recently, a new method was developed that allows for in vivo assessment of brain oscillations during tDCS (published in Nature Communications, one of the highest impact journals in the field). Given the controversy around tDCS effects, stating that the mechanisms are unknown seemed appropriate, and referring to recent neurotechnological advancements that promise to uncover these mechanisms did not occur to me being "spam referencing".

Also, use of terms like "no good evidence" or "somewhat effective" seems vastly imprecise for an encyclopedic article. Either there is evidence or not, so why not better provide the actual information about effectiveness (or its absence) by referring to the effect size as calculated by Horvath et al. It should be noted, though, that Horvath's let to substantial controversy in the field due to methodological issues. I have thus toned down the paragraph by revising into:

While there is limited evidence that tDCS is useful for cognitive enhancement in healthy people (probably due to ceiling effects), memory deficits in Parkinson's disease and Alzheimer's disease,[4] schizophrenia, pain, or improving upper limb function after stroke, tDCS appears to be effective for treatment of depression.

Best wishes! Elias A. Rosenberg (talk) 09:39, 14 June 2016 (UTC) — Preceding unsigned comment added by Elias A. Rosenberg (talk • contribs)

Mechanisms of action, specificity and historic roots
Dear Jytdog, please find comments to the revisions (in bold) that I suggested to the tDCS article:

Transcranial direct current stimulation (tDCS) is a form of neurostimulation which uses constant, low current delivered to the brain area of interest via electrodes on the scalp.

This statement is not true, as it is unknown whether and where the brain is stimulated when attaching electrodes to the head and delivering very weak currents. 99% of the current flows over the skull, while 0.9% is shunted through the cerebral fluid and 0.1% of the currents actually enters the brain (but probably not immediately underneath the electrodes). Thus, stating that currents are delivered to the brain area of interest is misleading. Please also read the recent article in Science Magazine on this issue: http://www.sciencemag.org/news/2016/04/cadaver-study-casts-doubts-how-zapping-brain-may-boost-mood-relieve-pain

''It was originally developed to help patients with brain injuries or psychiatric conditions like major depressive disorder. tDCS appears to be somewhat effective for treatment of depression. However, there is no good evidence that it is useful for cognitive enhancement in healthy people, memory deficits in Parkinson's disease and Alzheimer's disease, schizophrenia, pain, nor improving upper limb function after stroke.''

This whole paragraph is misleading. First, tDCS was already applied by the ancient Egyptians using electric catfish and found its way into the literature about 200 years ago (http://www.aipass.org/files/TDCS_State%20of%20the%20art.pdf). It was certainly not purposefully "developed" to treat brain injuries. The underlying mechanisms of tDCS are widely unknown (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4368894/) as it was impossible to record brain oscillations (brain electric activity) during tDCS. However, recently, a new method was developed that allows for in vivo assessment of brain oscillations during tDCS (published in Nature Communications, one of the highest impact journals in the field). Given the controversy around tDCS effects, stating that the mechanisms are unknown seemed appropriate, and referring to recent neurotechnological advancements that promise to uncover these mechanisms did not occur to me being "spam referencing".

Also, use of terms like "no good evidence" or "somewhat effective" seems vastly imprecise for an encyclopedic article. Either there is evidence or not, so why not better provide the actual information about effectiveness (or its absence) by referring to the effect size as calculated by Horvath et al. It should be noted, though, that Horvath's let to substantial controversy in the field due to methodological issues. I have thus toned down the paragraph by revising into:

While there is limited evidence that tDCS is useful for cognitive enhancement in healthy people (probably due to ceiling effects), memory deficits in Parkinson's disease and Alzheimer's disease, schizophrenia, pain, or improving upper limb function after stroke, tDCS appears to be effective for treatment of depression.

All these points resulted into the following version:

"Transcranial direct current stimulation (tDCS) is a form of neurostimulation which uses constant, low current delivered via electrodes placed on the scalp. The mechanisms underlying tDCS effects are still incompletely understood, but recent advances in neurotechnology allowing for in vivo assessment of brain electric activity during tDCS promise to advance understanding of these mechanisms. While there is limited evidence that tDCS is useful for cognitive enhancement in healthy people (probably due to ceiling effects), memory deficits in Parkinson's disease and Alzheimer's disease, schizophrenia, pain, or improving upper limb function after stroke, tDCS appears to be effective for treatment of depression."

It would be great to discuss these points! :) Elias A. Rosenberg (talk) 20:02, 17 June 2016 (UTC)
 * am out of WP time today but I will come back on this over the weekend. thx for talking. Jytdog (talk) 20:08, 17 June 2016 (UTC)

tDCS controversy suppressed
Alexbrn cites WP:MEDRS as a basis for suppressing any suggestion (based on primary sources) that there may be a controversy about whether it is effective in mental stimulation of healthy people. This is a misguided extension of the intent of WP:MEDRS which discourages statements of fact based on primary sources. I have made edits to inform readers of the existence of this controversy and the basis for it. Why suppress that fact? Would Alexbrn be happier if it were incorporated in a section entitled "Controversy"? sirlanz 04:26, 9 November 2016 (UTC)
 * Did I miss something? Does RS say there is "controversy"? Alexbrn (talk) 06:17, 9 November 2016 (UTC)
 * Please read WP:MEDREV which explicitly says that it is not OK to "overrule" recent reviews with primary sources. Explicitly. Jytdog (talk) 06:22, 9 November 2016 (UTC)
 * First, thanks to both editors for their guidance and contribution. I have not ventured into the medical space frequently (if at all) and this is the first time I've encountered MEDRS/MEDREV.  I have to say I'm surprised to find that an entirely different standard is adopted for this class of article (if these two guides are to be followed).  The way I see it, the primary function of an encyclopaedia is to provide facts to help readers as a first port of call in improving their understanding of a topic.  In so doing, the encyclopaedia may answer questions with a kind of finality; sometimes it won't.  If I'm right about that (and someone may think otherwise, of course), if there are competing views on any aspect of significance in a topic, the encyclopaedia ought to disclose them.  Now, I do understand the important distinction made between primary and secondary sources (and I accept that this is particularly important in the medical context) but how can it be that when a group of members of a profession make a finding, which is published in a journal of the discipline (and let's say not just a journalists' rag), which runs contrary to many earlier findings, that that finding must be expunged entirely from disclosure to the reading public?  Who are we to censor factual information on any subject, be it medical or otherwise?  It must be noted that the new contrary primary source was not included as uncontroverted fact by me but as a source of controversy.  And surely if one set of members of a profession believe otherwise than the rest, does not a controversy therein lie per se?  sirlanz 01:41, 10 November 2016 (UTC)
 * WP:MEDRS is 100% aligned with and under the relevant WP policies WP:V, WP:OR, and WP:NPOV and aligned with WP:RS. The emphasis on secondary sources is especially important due to the nature of the subject matter and the literature.  If you want more background, you might find the essay, WP:Why MEDRS?, helpful.  I initially drafted it but it has been moved to WPspace and edited by others since then.  It is intended to explain MEDRS to folks who are not familiar with biomedical literature and the subject matter.  Jytdog (talk) 05:47, 10 November 2016 (UTC)

Image caption makes zero sense
Take a look at the newly-added image at the top of the article as of 19 April, 2017. The a-e label legend makes no sense. (a) is supposedly an electrode(??) but it's clearly pointing at the voltage source. (e) is a rubber band "to reduce resistance" but rubber bands don't reduce resistance, and the arrow is apparently pointing at a chin strap.

Can anyone figure out what the editor meant to have these annotations mean? IAmNitpicking (talk) 13:31, 19 April 2017 (UTC)


 * Looking at the image on Commons, whoever transferred the caption ignore a rather important full stop which caused the confusion with the electrode labelling. I have fixed this. I cannot help with the rubber band question. Presumably there must be a source somewhere that explains how the device is used which might be useful to refer to. PriceDL (talk) 16:29, 19 April 2017 (UTC)

Research
The first paragraph of the research section says:

A 2015 study that reviewed results from hundreds of tDCS experiments found that there was no statistically conclusive evidence to support any net cognitive effect, positive or negative, of tDCS in healthy populations - there is no evidence that tDC is useful for cognitive enhancement.[3] A second study by the same authors found there was little-to-no statistically reliable impact of tDCS on any neurophysiologic outcome.[4]

I read both studies mentioned above. The authors discuss some important limitations that we may want to mention in the wiki article. For example, the first study is titled ``Quantitative Review Finds No Evidence of Cognitive Effects in Healthy Populations From Single-session Transcranial Direct Current Stimulation``. The authors point out that an important limitation of the study is that they only considered single-session TDCS.

Except from the limitations section of the study:

This paper only explores cognitive measures undertaken during or following one session of tDCS. As noted in the results section, there are many studies which have utilized a multiple-day stimulation paradigm (e.g. Refs. [39,65,79,108]). It is wholly possible that several sessions of tDCS are required in order for a reliable effect to be seen. In this instance, it has been argued tDCS impacts cognition via repeated exposure and, possibly, overnight consolidation (see: Refs.

Would it be a good idea to mention this limitation in the Research section? Scottlawsonbc (talk) 01:19, 10 December 2016 (UTC)


 * That would be a good idea – and the first Horvath et al. study has additional limitations that the article ought to mention. Horvath et al. only looked at between-group effects, and ignored within-group effects, which raises serious questions about their "No Evidence" conclusion (Chatbar & Feng, 2015). Other meta-analyses which included within-group effects, some of which including more studies than Horvath et al., have found evidence of tDCS efficacy for cognitive enhancement:
 * Coffman et al. (2014) reviewed 37 studies: "tDCS may be particularly well-suited for neuroenhancement" because anodal tDCS significantly improved executive functioning with an average effect size of +0.9.
 * Dedoncker et al. (2016) reviewed 61 studies which all included within-subject analysis: Anodal DLPFC "tDCS significantly decreased [reaction times] in healthy participants, and increased response accuracy in neuropsychiatric patients" while "In healthy participants, increased current density/charge are associated to increased a[nodal]-tDCS effects on response accuracy."
 * Hill et al. (2016) reviewed 16 studies: anodal DLPFC tDCS significantly improved performance on some working memory tasks, while trending towards improvement for reaction times in healthy subjects.
 * Katsoulaki et al. (2017) reviewed 10 studies: "All studies showed that anodal tdcs co-administered with cognitive tasks can significantly enhance working memory performance."


 * I propose we change the third sentence of the article from this...

"However, there is no good evidence that it is useful for cognitive enhancement in healthy people,[4][5] memory deficits in Parkinson's..."
 * ...to this:

"However, there is mixed evidence about whether tDCS is useful for cognitive enhancement in healthy people. Several reviews have found evidence of small yet significant cognitive improvements.[Coffman et al. 2014][Dedoncker et al. 2016][Hill et al. 2016][Katsoulaki et al. 2017] Others found no evidence at all,[Horvath et al. 2015a][Horvath et al. 2015b] although one of them[Horvath et al. 2015a] has been criticized for overlooking within-subject effects[Chatbar & Feng, 2015] and evidence from multiple-session tDCS trials. There is no good evidence that tDCS is useful for memory deficits in Parkinson's..."
 * (With properly formatted citations, of course. And I apologize for replying to a 2-year-old comment, but this article's intro has bothered me because it misled me about tDCS for a while.) GregConan (talk) 09:51, 16 September 2018 (UTC)