Aug 14, 2014

Everything you want to know about tDCS

So I’ve been looking forward to sharing my notes on this life-changing technology known as Transcranial Direct-Current Stimulation, or "tDCS", for quite a while now, but condensing the exponentially increasing trove of data on the subject proved far harder to do than anticipated.

Alas, below you'll find my first attempt at a high-level summary of tDCS technology, as well a collection of what I found to be the most compelling information and scientific basis for its benefits:

Before you go further, please know that as incredible as what you're about to read sounds, every claim in the text to follow is supported by myriad clinical studies and objectively quantifiable scientific evidence.  I can say without reservation that it worked miraculously for me, and I now evangelize for the technology at every chance I get.

The framework for the tech I keep referencing has been around for 200 years.  Though it languished basically ignored (industry preferring the far more lucrative pharmaceutical means of addressing all that ails us); lately however tDCS has been gaining a great deal of attention and praise as an efficacious and safe alternative to drugs.

How does it work?  It's as simple as attaching one electrode to your scalp (above the part of the brain you want to stimulate), and another electrode either on somewhere innocuous like your shoulder (at a site on your scalp above an area of the brain you want to inhibit).  

The two electrodes form a circuit of sorts in the body.  Then you turn on the juice!  

Figuratively anyway.

In actuality you're only sending somewhere between 1 to 2 milliamperes of electricity through the brain, but the reported effects have seemed, in many instances, too good to be true.

Almost every expert who talks about tDCS will tell you, “Don’t try this at home.” But fact is, a lot of people are starting to do just that. And it’s no wonder, given the parade of amazing results that researchers have reported achieving on subjects in the lab. It seems like you can make people better at just about anything if you just put the electrodes in the right place. To name just a few of the findings:

  • Applying the electrodes to the prefrontal cortex can improve learning and increase your working memory. 
  • Stimulation of the parietal cortex can improve numerical reasoning.
  • Applying tDCS to the motor cortex can raise your threshold for pain and even make you more adept with your non-dominant hand. 
  • Position the electrodes (the different coordinates on the scalp and head where the electrodes are placed are known as a “montages”) above the posterior portion of the left perisylvian area (in right-handed people) and tDCS can facilitate rapid language acquisition. 

And the list goes on and on, from depression, to motor reflexes, to recovery from all sorts of ischemia and neural insults.  Very quickly we’re seeing a surge in tDCS interest and use across a wide spectrum of early adopters.  tDCS is increasingly being employed to significantly speed the healing and restore functionality in stroke victims, and on the other end of the spectrum was recently deployed by every branch of the United States military to effectively train soldiers (sometimes twice as fast!) in skills that vary from flying fighter jets to firing sniper rifles! 

“The military has been looking at how to improve vigilance for the past 50 or 60 years,” said Andy McKinley, a civilian biomedical engineer who has been studying tDCS at the Air Force Research Laboratory at Wright-Patterson Air Force Base in Ohio.“At minimum we get a twofold improvement in how long a person can maintain performance. We’ve never seen that with anything else.”

A few studies claim results that are even more jaw-dropping. In Neuroscience Letters last year, Australian researchers reported applying tDCS to 33 people as they tried to solve the notoriously tricky “nine-dot” logic problem. Not one was able to crack it without stimulation, or with “sham” stimulation (in which electricity is applied only briefly to mimic the feeling of tDCS).  However, among those augmented with tDCS,40 percent of that group solved it! 

You might suspect the procedure would be painful or unpleasant. Many subjects report a tickling or burning sensation from the electrodes, and some say they feel different when the current is flowing, with time seeming to pass quickly. But far from finding it painful, an editor at New Scientist who tried it out during a marksmanship test described tDCS as “the most powerful drug I’ve ever used in my life” and “a near-spiritual experience.”  The editor, Sally Adee, wrote:

“When a nice neuroscientist named Michael Weisend put the electrodes on me, what defined the experience was not feeling smarter or learning faster: The thing that made the earth drop out from under my feet was that for the first time in my life, everything in my head finally shut up. …  I felt clear-headed and like myself, just sharper. Calmer. Without fear and without doubt. From there on, I just spent the time waiting for a problem to appear so that I could solve it.” 

Oh, and she nailed the target.

Here's a company that I bought my tDCS unit from:

Let me know if you have any questions further questions about this very interesting tech.  I'd be happy to help however I can.

Below you’ll find an extensive collection of additional notes and scientific basis I aggregated from various studies online, as well a peppering of some of my own thoughts and experiences with tDCS:

tDCS Notes:

To give its full name, tDCS stands for “transcranial direct current stimulation”. Transcranial simply means that the direct current (i.e. from a battery rather than the AC mains) is passed across a region of your brain. In the case of the headset that I’ve been testing, the direct current passes between the cathode and anode, which are placed over your prefrontal cortex using a fixed-position montage that’s designed to have either an excitatory or inhibitory effect.

Different montages elicit different effects, one could position the tDCS system to improve mathematical reasoning, or when the anodes and cathodes of a tDCS system are positioned to activate cortical neuronal systems, neurons are primed to fire faster and elicit faster reaction times in the wearer.   

Even when the tDCS session is terminated the beneficial effects are proven to continue enhancing the subjects ability to learn new skills. These effects have been proven to continue post-session for not less than 1-2 hours.

Transcranial direct current stimulation (tDCS) is a form of neurostimulation which uses constant, low-current delivered directly to the brain through various vectors or “montages” (benefits to unique cognitive functions are dependent on where the tDCS electrodes are placed on the scalp).

tDCS was originally developed to help patients with brain injuries such as strokes. However, more recently tests on healthy adults have demonstrated that tDCS can increase cognitive performance on a variety of tasks, (again depending on the area of the brain being stimulated).

tDCS has thus far been utilized to enhance language and mathematical ability, attention span, problem solving, working memory, learning, and coordination.  In some of the more interesting studies below you'll learn that tDCS has enhanced a overall learning speed by a factor of 230%!

tDCS can modify brain behavior by inducing changes in its function. To better understand the effects of tDCS, study examines tDCS' impact on performance on working memory and underlying neural activity

Below is a collection of some of my favorite articles and information resources on tDCS:

"Anodal tDCS" may be overall better than "cathodal tDCS", though at least one study disputes that belief.

Excellent informational resource detailing proper use of tDCS technology as well as offering useful insights into tDCS montage locations (translated: instructions that show where to place anodes and cathodes to get certain benefits):

Here are my back-of-the-napkin ratings for each tDCS device available for purchase by an ordinary consumer.  These ratings don’t take price into consideration.  If they did, I believe the tDCS headset to be the best device on the market today:




The product used by Atlanta based clinic you can find at: 

Additional tDCS manufacturers, suppliers, and DIY instruction sites:

Manufacturers and suppliers of tDCS parts or alternatives to tDCS:

Interesting product providers (various uses):

Excellent tDCS article:

Anode and Cathode placement on scalp:  

Further definitions and articles:

A widely cited definition characterizes cognitive enhancement as “interventions in humans that aim to improve mental functioning beyond what is necessary to sustain or restore good health”

The term “cognitive enhancement” usually characterizes interventions in humans that aim to improve mental functioning beyond what is necessary to sustain or restore good health. While the current bioethical debate mainly concentrates on pharmaceuticals, according to the given characterization, cognitive enhancement also by non-pharmacological means has to be regarded as enhancement proper. Here we summarize empirical data on approaches using nutrition, physical exercise, sleep, meditation, mnemonic strategies, computer training, and brain stimulation for enhancing cognitive capabilities. Several of these non-pharmacological enhancement strategies seem to be more efficacious compared to currently available pharmaceuticals usually coined as cognitive enhancers. While many ethical arguments of the cognitive enhancement debate apply to both pharmacological and non-pharmacological enhancers, some of them appear in new light when considered on the background of non-pharmacological enhancement.

How it works:

The physiological changes involve the modulation of spontaneous neuronal activity through polarity-specific shifts of the resting membrane potential in the direction of de- or hyperpolarisation. The direction of the change is governed by the direction of current flow, the spatial orientation of the neuron, the type of neuron and the total charge.


The ability to detect errors during cognitive performance is compromised in older age and in a range of clinical populations. This study was designed to assess the effects of transcranial direct current stimulation (tDCS) on error awareness in healthy older human adults. tDCS was applied over DLPFC while subjects performed a computerized test of error awareness. The influence of current polarity (anodal vs cathodal) and electrode location (left vs right hemisphere) was tested in a series of separate single-blind, Sham-controlled crossover trials, each including 24 healthy older adults (age 65–86 years). Anodal tDCS over right DLPFC was associated with a significant increase in the proportion of performance errors that were consciously detected, and this result was recapitulated in a separate replication experiment. No such improvements were observed when the homologous contralateral area was stimulated. The present study provides novel evidence for a causal role of right DLPFC regions in subserving error awareness and marks an important step toward developing tDCS as a tool for remediating the performance-monitoring deficits that afflict a broad range of populations.

All known human societies have maintained social order by enforcing compliance with social norms. The biological mechanisms underlying norm compliance are, however, hardly understood. We show that the right lateral prefrontal cortex (rLPFC) is involved in both voluntary and sanction-induced norm compliance. Both types of compliance could be changed by varying the neural excitability of this brain region with transcranial direct current stimulation, but they were affected in opposite ways, suggesting that the stimulated region plays a fundamentally different role in voluntary and sanction-based compliance. Brain stimulation had a particularly strong effect on compliance in the context of socially constituted sanctions, whereas it left beliefs about what the norm prescribes and about subjectively expected sanctions unaffected. Our findings suggest that rLPFC activity is a key biological prerequisite for an evolutionarily and socially important aspect of human behavior. 

It's still so early, but this is very exciting:

Remarkably, MRI brain scans revealed clear structural changes in the brain as soon as five days after TDCS. Neurons in the cerebral cortex connect with one another to form circuits via massive bundles of nerve fibers (axons) buried deep below the brain's surface in "white matter tracts." The fiber bundles were found to be more robust and more highly organized after TDCS. No changes were seen on the opposite side of the brain that was not stimulated by the scalp electrodes. Amping Up Brain Function: Transcranial Stimulation Shows Promise in Speeding Up Learning

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

Antidepressant drugs and psychotherapy are the first line treatments for depressive disorders. If efficacy is not satisfactory, supplementary biological treatment procedures can be used. Transcranial magnetic stimulation (TMS) has established itself as a possible new approach in the treatment of depressive disorders. The hypothesis is that stimulation of areas relevant to the pathophysiology of depressions will induce metabolic and biochemical processes—both in the stimulated areas and in associated subcortical regions—that have an anti-depressive effect. On the basis of this pathophysiological model, tDCS was investigated as another non-invasive method of brain stimulation. The approach is based on the physiological knowledge that anodal stimulation of nerve cells, i.e. stimulation with positive charge, causes a depolarization of the membrane potential in the underlying neurons, whereas a negative external charge from a cathode hyperpolarises a negative membrane potential.

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