I've built one for ~ $30 in parts from Radio Shack using an LM317 current limiter. There is an odd bootstrapping problem involved with tDCS devices: you need to have the device connected to comprehend the instructions! Researchers speak of anodal and cathodal stimulation, and the convention is that + is anodal and - is cathodal. So far so good--at least this comports with vacuum tube conventions, which will be familiar to all readers of Hacker News. Researchers speak of anodal stimulation of the left dorsolateral prefrontal cortex. The tDCS device has to be connected (with the positive connection over the left dorsolateral prefrontal cortext) to even begin to comprehend that left means left from the perspective of the subject, but right from the perspective of a viewer viewing the subject's face. The right negative contact can go over the right eyebrow (but there are other protocols). This is one of the clearest: http://www.ncrrn.org/papers/symposium_tdcs/hamilton_tdcs.pdf.
As you can see, there is an inviolable convention among researchers not to unambiguously mark the anode + contact on the left dorsolateral prefrontal cortex, and the cathode - contact over the subject's right eyebrow. Instead, what we see on the third slide is a cartoon drawing of a subject in which two contacts are labeled "active" and "reference". There is an arrow leading from the active contact to the reference contact labeled "anodal" and another arrow from the reference contact labeled "cathodal". This refers to an ancient convention in electronics, in which current was assumed to flow from the anode to the cathode, even though electrons flow from the cathode to the anode. The literature is replete with such helpful diagrams. One would like a completely unambiguous statement: the anode is the positive connection, and it is secured to the left side of the subject's scalp; the cathode is the negative connection, and it secured over the subject's right eyebrow. Or one of the eight combinations possible by arbitrarily switching anode with cathode, positive with negative, and left with right. But I have been unable to locate a statement in the literature that would condescend to so direct and simple a description.
Here is another article with a diagram showing node placement for tDCS. http://www.sciencedirect.com/science/article/pii/S0165017306.... Note that the anode is placed over the left dorsolateral prefrontal cortex, and the cathode is placed on the forehead. That beats the anodal and cathodal arrows of the previous diagram. What we still don't have is the identification of + with anodal and - with cathodal. And so one must continue searching through the literature--which should be done in any case--until one comes to something approximating a consensus on node placement and the meaning of anodal and cathodal versus positive and negative.
Finally, here's a compilation from a less than unimpeachable source: http://www.drmueller-healthpsychology.com/tDCS.html.
The author misreads 1mA as one microamp. That's one milliamp. But we do get a straightforward statement about node placement from Fregni, F., Boggio, P., Nitsche, M., et al. (2006). Letters to the Editor: Treatment of major depression with transcranial direct current stimulation. Bipolar Disorders, 8:203-205. This is confirmed in http://www.ncbi.nlm.nih.gov/pubmed/22031874, though you have to know that anode means positive and cathode means negative.
I should say that in my initial reckless period of self-experimentation, I managed to induce phosphenes by accident -- blue white flashes in the entire visual field, blanking out everything else. Both contacts were in the supraorbital region. I ceased my experiments for a while and returned to the literature.
So, after reading this account, I felt compelled to wire up my current-limited power supply at 1mA and ranges from 6-9V using saline-soaked paper towels.
Got some mild phosphenes during the first try by putting the anode too far forward -- although not in my entire visual field like the author, instead just at the top, and the phosphenes stopped once the electrode was securely connected.
OP, what duration do you use? http://www.ncbi.nlm.nih.gov/pubmed/17940759 indicates that "short-term" is <1s and "long-term" is 10m. It's hard to say objectively, but I think after about 1m I can feel increased concentration and wakefulness.
Initially 5 min, increased to 20 min. Phosphenes are not uncommon if the anode is too far forward and if the circuit is intermittent. Ramping the current up and down is a good idea. I would only use a battery powered supply myself. The video http://www.jove.com/video/2744/electrode-positioning-and-mon... mentioned above is excellent, incidentally (wooden acting aside).
Interesting video -- watching it made me realize that my ad-hoc "electrodes" were too small (2x2 cm), explaining the mild skin irritation. I wonder if it's common also to have a temporary, very moderate blurred vision in the right eye (only during stimulation)? It would make sense considering the cathode inhibits depolarization there. I'll keep reading.
Thanks for posting, this has been an interesting experience.
for 1mA 35cm2 50uA/cm2 i use 30 min (L-DLPFC and right orbital)
for 2mA 9cm2 in higher current density work much faster efect is precivable after few second (aplication 3min) bud ther is a problem - skin iritation and is little itchi
(early expediments)
in publication is recomandet current density under 60uA/cm there was much more but still under tishue damge limit
IIRC, I had it memorized by thinking that "anions" move towards the "anode" ; since "anions" are negative ("anion" = A Negative ION :D ), then the "anode" must be positive... I'm not a EE major, so I could be wrong.
I used it again yesterday after a long time.
I do not use it too often because I have other methods to achieve the same effect using the mental techniques.
I use it only if there is headache and it is too difficult to concentrate to mental techniques.
Effect very depends on start state mostly on levels of stress hormons in the body.Here some early tests http://brmlab.cz/project/brain_hacking/tdcs (part tests)
I planed to do more test (i made aroud 50 , but the dont documted),currently working on other projects but plans to come back and improve it (mostly the electrode position and current density).
--------
If you want to use higher current use 2x9V baterry ,there must be enough volts to equalize the resistance changes.
( resitence electodes+head is about 2-5kOhm)
In Physical Chemistry / Galvanic cells, the anode is defined to be the location where the oxidation reaction occurs, and the cathode is where the reduction reaction takes place. It has nothing to do with cations/anions since cations can be generated by both chemistries.
This was the source of much confusion in biochem (electrophoresis) for many students because negative charges migrate to the anode.
This is anecdotal, and I have not followed rigorously the experimental protocols of any of the papers I have cited, nor have I subjected myself to tests of retention, calculation or reaction time. Nevertheless, I believe the device has enabled me to achieve a higher karma score on Hacker News. I have authored a paper on mathematical logic after a period of previously drafting notes, and have had success with the integration of large-scale multi-disciplinary environmental systems models. Finally I believe the cognitive gains my unlicensed, home-made DIY tDCS device have enabled are sufficient to overcome the bias that otherwise would have left me unemployed (cf. http://www.nytimes.com/2012/01/29/us/bay-area-technology-pro...).
It sounds like you have to be wearing the device in order to benefit from it. Do you work from home while "plugged in"? Or, can you just use it while thinking about a tough problem or while learning something new and then when it's turned off still have the insights/new knowledge you gained?
When did you build the device? It seems like you must have known about this for some time since you say it helped you get a job. Meanwhile, the article on Oxford's site was just posted today. How did you find out about it?
I started reading the literature on tDCS in November, 2010. There have been articles in the popular science press on tDCS at least since then. I was motivated to build the device after reading an article in Scientific American from November 2011, one year later: http://www.scientificamerican.com/article.cfm?id=amping-up-b... And now I must get back to work...
i iknow tDCS about 4years and test it about 3 , but eraly test it vas only 9volt batery , potentiomether(I must regulate current manualy) and 2 electrode from watch cover
Someone should bring this to market, or at least make a DIY kit available. It sounds super fascinating to experiment with (at super low levels). Perhaps someone from Make is reading this -- if so, this would be a great project to feature!
Reading your post, it occurred to me that its tone sounds very similar to things I've written when I had had a lot of caffeine, or was on methylphenidate ("Ritalin") for a long time. In my case, prolonged methylphenidate use induced mild psychosis, a known effect that is common in long-term users of the pharmacokinetically similar amphetamine family, which also dramatically improves learning performance.
Thus extrapolating, I wonder if tDCS use might also induce psychosis.
Going off methylphenidate on the weekends ameliorated the psychotic effects, but some of the psychosis-induced beliefs persisted for quite a while.
maybe yes overstlimulation can boost data procesing in brain
in extreme cases start hyperasociative states where is conect information than not normali linked.
there is only small border between geniality(new ideas) and madnes
Sorry if I'm being dense, but where is that 2 mA measured? It only has three pins: input, output, and reference. There's no ground pin. The reference presumably draws almost no current, as drawing significant current would affect the measurement. So the current on the input & output must be the same, and the same as what we're feeding into the electrodes. No? Does this just mean you can't use the simple circuit composed entirely of the LM317 and a single resistor between the output pin and the reference?
Sorry my mistake, I was talking without looking at the datasheet.
From the datasheet
>all quiescent operating current is
returned to the output terminal. This imposes the
requirement for a minimum load current. If the load current
is less than this minimum, the output voltage will rise.
I've used an LM317 drawing less than 2mA, so I assumed it was possible (in hindsight I must have used the solution, below).
The solution is very simple however, make a separate parallel circuit that will draw at least 2mA. This can be accomplished just by placing a resistor of appropriate value between the Vout and ground.
ChristianMarks said in one of his comments that he believes the device has allowed him to overcome a bias in the valley against hiring older engineers. Why would he want to reveal the details of a device that if widely used could erode his advantage?
At first I wasn't going to mention this (lest it become the reason he doesn't share the details), but then I realized, here's a smart guy who has a device that makes him even smarter, so I figure he probably already knows. :)
Well, I'm curious, can you quantify the lift from this vs, say, a healthy but sedentary person going on a regular exercise program, eating salmon and vegetables every day, taking piano lessons, and conventional ways of boosting alertness and memory?
But I would contend that before you try something like tDCS, you probably should try to optimize other easier and much more beneficial parameters such as sleep,diet,immunity,vitamin dosage,supplemental dosage etc.
In the end a pocket tDCS device can really come in handy when something (GEB for example :)) gets really hard to understand.Its all about using it in moderation.
mental techniques there i using have the same effect like tDCS , but echniques requre trening and more time.For me is betst way combination of tDCS and this techniques , depennd of specific situation.
As you can see, there is an inviolable convention among researchers not to unambiguously mark the anode + contact on the left dorsolateral prefrontal cortex, and the cathode - contact over the subject's right eyebrow. Instead, what we see on the third slide is a cartoon drawing of a subject in which two contacts are labeled "active" and "reference". There is an arrow leading from the active contact to the reference contact labeled "anodal" and another arrow from the reference contact labeled "cathodal". This refers to an ancient convention in electronics, in which current was assumed to flow from the anode to the cathode, even though electrons flow from the cathode to the anode. The literature is replete with such helpful diagrams. One would like a completely unambiguous statement: the anode is the positive connection, and it is secured to the left side of the subject's scalp; the cathode is the negative connection, and it secured over the subject's right eyebrow. Or one of the eight combinations possible by arbitrarily switching anode with cathode, positive with negative, and left with right. But I have been unable to locate a statement in the literature that would condescend to so direct and simple a description.
Here is another article with a diagram showing node placement for tDCS. http://www.sciencedirect.com/science/article/pii/S0165017306.... Note that the anode is placed over the left dorsolateral prefrontal cortex, and the cathode is placed on the forehead. That beats the anodal and cathodal arrows of the previous diagram. What we still don't have is the identification of + with anodal and - with cathodal. And so one must continue searching through the literature--which should be done in any case--until one comes to something approximating a consensus on node placement and the meaning of anodal and cathodal versus positive and negative.
Finally, here's a compilation from a less than unimpeachable source: http://www.drmueller-healthpsychology.com/tDCS.html. The author misreads 1mA as one microamp. That's one milliamp. But we do get a straightforward statement about node placement from Fregni, F., Boggio, P., Nitsche, M., et al. (2006). Letters to the Editor: Treatment of major depression with transcranial direct current stimulation. Bipolar Disorders, 8:203-205. This is confirmed in http://www.ncbi.nlm.nih.gov/pubmed/22031874, though you have to know that anode means positive and cathode means negative.
I should say that in my initial reckless period of self-experimentation, I managed to induce phosphenes by accident -- blue white flashes in the entire visual field, blanking out everything else. Both contacts were in the supraorbital region. I ceased my experiments for a while and returned to the literature.