User x0rn just posted this to the tDCS SubReddit. Check original source (link at bottom) for updates.
Jesse interviews Nathan Whitmore, creator of the open-source project OpenBrainStim, an affordable alternative to commercial transcranial Direct Current Stimulation (tDCS) devices. Nathan tells us how the project got started, how the “DIY-tCDS” community has grown, and how you can experiment from the comfort of your own home.
Brent Williams of SpeakWisdom just published a checklist for DIY tDCSers. Links at bottom to full list.
DIY tDCS Safety Standards
As a potential or current do-it-yourself tDCS user I agree to the following:
1. I will, if reasonably possible, seek out a medical professional for tDCS advice, treatments and follow-up.
2. If I have cranial scar tissue, an implant, or other unusual medical condition, I will seek clearance from my doctor before using tDCS. If I have a seizure disorder I will refrain from using tDCS or use it only under direct supervision of qualified medical personnel.
3. I will not, under any circumstances, directly connect a battery to my head. I understand that I could greatly exceed the maximum 2 mA current limit used by tDCS researchers, possibly harming myself in the process.
That’s what Jared Seehafer did. He’s a 28-year-old medical device consultant in San Francisco who heads the group.
He made his own tDCS machine using an elastic headband and a couple of electrodes. It’s powered by a 9-volt battery and produces 1 to 2 milliamps of electricity, approximately what it takes to light one small LED bulb.
Regarding the transients at turn on, that is a circuit issue. So to remedy, it is easy to add an LC filter at the output see picture below for new schematic. The LC filter acts to dampen any transients. Bench testing shows the ramp up to be 500ms, which is plenty to dampen any turn on pulses, but unfortunately not enough to prevent any flash that occurs with certain montages. At mouser.com, the L can be 22R105C and the C can be UKL1E100KDDANA.
Petr, whose first language is Czech, asks…
Ramping capacitor – possible problem
Yesterday i was building some tDCS with LM334 and try for first time use ramping capacitor. When i test device with load (5KOhms) all was ok ramping when i turn device on and ramping down when off. But when i change load (5kOhms potentiometer) during stimulation (testing) it create current peak up to 5 mA. I test it with few different capacitor and behavior is always the same (only different value of peak and the time to return to normal ). Device without capacitor work without problem. In result of this i use instead of capacitor serial load ( linear potentiometer 100kOhms ) allows me to do manual ramping (0,07mA to setup current).
My question is can anybody test this capacitor problem maybe i do something wrong, bad multimeter etc.. . If this problem is real, it’s a very bad idea to use capacitor for ramping in use the resistance change is not too quick but still can cause pretty high current peaks.
Brent Williams of SpeakWisdom (we met him earlier on the blog) has started a YouTube tDCS series. This is his second in the series. This is an excellent overview of the basic components of tDCS, however, Brent does not recommend you actually build
and use a resistor-based device. Brent mentions that upcoming videos will demonstrate how to build a current-regulated device.
Hard to imagine how he’d have learned enough about tDCS to build a device, but have gotten the (typical) montage so wrong. Placing the cathode over left DLPFC and anode over right orbital is exactly the opposite of what you’ll find in most studies related to both depression and working memory. He doesn’t go into how he’s constructed his electrodes at all. Anecdotally, it is interesting that the reverse montage made him feel angry and depressed.
Some very excellent tDCS-related documents came to my attention over the weekend. I’m pretty sure I’d looked for at least one of them before, but that it was behind a paywall. I’ll provide links to the pdfs here, but suggest that (as has happened elsewhere on the blog) pdf links frequently go bad so ‘get em while they’re hot’.
Brain stimulation enables the solution of an inherently difficult problem (pdf)
This is the paper by Alan Snyder and Richard Chi that is frequently referenced in ‘unlock your inner savant’ articles on various pop-sci sites. (See also) Spoiler alert! Gives the answer to the ’9 dot’ problem and once you’ve seen it it will be impossible to discover how ‘savant-like’ you are (at least according to this test).
…we applied cathodal tDCS (1.6mA) at the left anterior temporal lobe (ATL) together with anodal tDCS at the right ATL for approximately 10 min… None of the 22 participants in the main experiment solved the nine-dot problem before stimulation. But with 10 min of right lat- eralizing transcranial direct current stimulation (tDCS), we found that more than 40% of participants could do so.
Dr. Brent Williams, at his SpeakWisdom blog, published another excellent tDCS post updating his DIY device, and adding a .doc that outlines his recommended (For Discussion) protocols for depression, ‘Savant Learning’, memorization, and chronic pain.
His protocol describes directions for use with either his ‘User-Built tDCS Research Device’, or the ActivaDose II.
Transcranial Magnetic and Electric Stimulation in Perception and Cognition Research (pdf)
This is a fascinating paper (Carlo Miniussi et al) that brings us up to date (2012) on applications of tDCS, TMS tACS (transcranial alternating current), and tRNS (transcranial random noise stimulation), especially in relation to cognition and learning. What really caught my eye was this entry about tRNS…
tRNS consists of the application of a random electrical oscillation spectrum over the cortex. tRNS can be applied at different frequency band ranges over the entire spectrum from 0.1 to 640 Hz…They applied tRNS to the visual cortices of healthy subjects and observed a significant improvement in the performance of healthy subjects in a visual perceptual learning task. This improvement was significantly higher than the improvement obtained with anodal tDCS…
And that folks, is how a weekend disappears down the rabbit hole!