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”


Transcranial Direct Current Stimulation, tDCS, Nootropics, Memory, Attention, Intelligence, Cognitive Enhancement

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.

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.

August 25 2013 Key notes:

TDCS is comparable to that of modern pharmacological drugs, with no negative side effects.

Nowadays, tDCS is a routine technique used for various pathologies at the Saint Petersburg Municipal Center for Medical Rehabilitation of Children with Psychoneurological Disorders (Pinchuk, 2007). Since 1988 till 2011, more than 1400 children and adolescents aged from 9months to 17years and more than 350 adult patients with various nervous system diseases have undergone tDCS treatment in the Center. tDCS procedures appeared to be also effective in the treatment of headaches (HA). Based on results obtained we tried to identify the possible mechanisms underlying the clinical effectiveness tDCS in the treatment of HA. We are aware that this work is as yet incomplete but taking into consideration the importance of the problem, great number of patients with HA, combined with the high degree of effectiveness of the technique and almost complete absence of undesirable effects, we consider advisable to inform specialists working in this field of our experience in using tDCS technique for HA treatment.

In the analyzed groups we used three basic localizations of stimulating electrodes on the scalp out of 17 used during tDCS. For the first electrode position (1EP), an anode was placed over the frontal pole (medial edge of the electrode was situated at the boundary of the interhemispheric fissure) of the hemisphere subdominant in motor skills; a cathode was located at the ipsilateral mastoid process. For the second electrode position (2EP), an anode was placed in the center of the forehead, 1.5cm above the nasal bridge, at the projection of the interhemispheric fissure; a cathode was placed 2cm higher the mastoid process of the hemisphere subdominant in motor skills. For the third electrode position (3EP), an anode was placed in the center of the frontal pole of subdominant hemisphere; a cathode was placed 2cm above the ipsilateral mastoid process.

Stimulation time was 30–45min both in children and adults; current intensity ranged from 60 to 90μA for children to 100–150μA for adults; electrodes were made of medical conductive rubber and were placed in 6.25cm2 saline-soaked multilayer flannel cases. The current densities we use (0.001–0.024mA/cm2) almost do not differ from those used in majority of studies on tDCS (0.029–0.066mA/cm2) (Bastani and Jaberzadeh, 2012), and they are in the range permitted by the Ministry of Health of the USSR (now the Russian Federation) when performing transcranial stimulation with galvanic (direct) current (0.01–0.2mA/cm2). By the way, these figures are almost the same as the parameters of current density which were used at the end of nineteenth to twentieth centuries (0.01–0.3mA/cm2). The time of stimulation we use (30–45min) is somewhat longer than the one traditionally used in procedures of tDCS (10–20min). However, in several studies (Schlaug and Renga, 2008) longer time is used (up to 30min). Lengthening the time of exposure leads to greater charge of electricity than during the traditional use; tDCS – 0.09–0.12C/cm2, where 1C is the amount of electric charge transported in 1s by a steady current of 1A (Stagg and Nitsche, 2011), in our studies these values range from 0.19 to 0.26C/cm2. Although, there are works where these values are higher than the ones we used. So in the study of Schlaug and Renga (2008) the maximum total charge was 2.4C/cm2. However, in this case the values are much lower than the acceptable safety regulations (up to 200C/cm2) (Yuen et al., 1981). The number of procedures for a course varied from five to nine with 4–7days interval. Stabilization of HA level was a criterion for treatment course completion. Treatment was conducted in compliance with modern generally accepted standards of biomedical ethics.

According to patients’ self-reports, tDCS, when using the 1EP, has led to fast HA relief (already during the first two to three sessions). This localization has been more effective at CPTH and migraine (more than in 85 and 78%, respectively), at FETTH (52%), at CTTH (only in two patients out of seven, i.e., 29%). The 1EP was more effective in patients with dominating increased tonus of parasympathetic nervous system (according to Lüscher test – so-called criterion of vegetative balance) (Belova and Shepetova, 2002).

With migraine, the number of attacks decreased; if developed, they were shorter and less intensive. The pattern of HAs changed: during the attack, HA was dull instead of acute and disappeared rather fast. Duration of pain attack reduced from 9–24 to 3–8h. The number of vegetative manifestations (flushes, feeling hot, sweating, nausea, etc.) sharply decreased. Amount of analgesics, relieving the attack, decreased from 2–6 to 1–2 tablets.

Chronic Post-Traumatic HA (CPTH)

After tDCS course in patients with CPTH, along with marked reduction in HA level, the following was observed: significant reduction of asthenic syndrome manifestations (reduced tiredness and irritancy, normalization of sleep), reduction, and in some patients almost complete disappearance of vegetative lability symptoms. In 52% of patients with CPTH, after tDCS course HA completely disappeared for at least 4.5months; in 28% of patients the number of days with HA decreased by at least 50% from baseline for at least 4.5months; tDCS had no effect in 20% of patients. Subjective assessment of HA level in patients with CPTH decreased by 3.5 points on average in the group (from 5.4±1.8 prior to the treatment to 1.9±1.2 after tDCS course, p=0.0006).

After tDCS course, in patients with FETTH the feeling of head compression reduced significantly or completely disappeared, the number of days without HA increased, amount of analgesics being taken reduced. Level of pain in patients with FETTH when using the 1EP reduced by 1.88 points on average in the group (4.92±2.89 prior to the treatment, 3.04±2.82 after the treatment, p=0.062). Positive clinical effect was obtained mainly due to the subgroup of patients with TTH combined with muscular tenderness of pericranial muscles. Out of 18 patients with TTH, receiving tDCS in the 1EP, TTH combined with pericranial tenderness was observed in 13 patients. Out of these 13 patients, HAs completely disappeared in 4 patients for a period longer than 4.5months; in 6 patients, the number of days with HA reduced by at least 50% compared with baseline for a period longer than 4.5months; only in 3 patients no effect was observed. tDCS clinical effectiveness assessed by the decrease of days with HA in total is 76.9% in the subgroup of patients with FETTH combined with pericranial tenderness. According to NRS, reduction of HA intensity is significant (from 5.05±3.01 prior to the treatment to 2.87±2.11, p=0.0429). Reduction of HA intensity significantly (p<0 .05="" 1ep="" 35-years="" a="" accompanied="" after="" all="" and="" anxiety="" associated="" at="" beck="" both="" by="" correlated="" course="" decrease="" depression="" dizziness="" due="" female="" fetth="" five="" font="" former="" ha="" has="" in="" increasing="" ineffective.="" inventory.="" inventory="" level.="" level="" manifestations="" nausea="" not="" of="" old="" patient="" patients="" pericranial="" procedure="" s="" spearman="" spielberger="" stabilized="" state="" tdcs="" tenderness="" terminated="" termination="" the="" third="" to="" treatment="" vegetative="" was="" week="" with="">

Although TTH and migraine are traditionally considered to be different diseases, a significant clinical effectiveness of the same electrode localization (the 1EP) at tDCS both in patients with migraine and in patients with TTH rather indicates common pathophysiological mechanisms in these HA types. We tend to agree with D. Greenberg et al. (2005), who consider migraine and TTH to be two opposite poles of a single clinical spectrum. Psychosocial stress is believed to be a provoking factor for TTH, and personality traits (high incidence of anxiodepressive and somatoform disorders) predispose to development of cephalgia (Karakulova, 2006). However, these factors and, in particular, anxiodepressive syndrome of varying degrees are revealed in almost 60% of migraine cases (Gusev et al., 1999; Osipova and Levin,2006). NRS HA intensity level correlated significantly with state anxiety parameters according to Spielberger’s Inventory and Beck Depression Inventory in our study both in patients with migraine and in patients with TTH.

Apparently, changes in balance of frontal cortex activity, its shift toward activation of left hemisphere frontal cortex, determining the positive emotional background, is one of the reasons for improvement following tDCS with the 1EP, taking into consideration anxiodepressive component in HA clinical picture (Deglin and Nikolaenko, 1975; Heller, 1993). tDCS inhibitory regimen (exposure more than 35min) (Pinchuk, 2007) applied on the structures of the right orbitofrontal cortex resulted in a decrease in its activity and in reciprocal activation of the left hemisphere released of the right hemisphere inhibiting influence. This leads to a marked mood improvement, reduced anxiety, more adequate assessment, and response to environment and to regression of concurrent psychovegetative symptoms and reduction of HA intensity.

Transcranial direct current stimulation with the 1EP has predominantly caused an increase of sympathetic ANS activity which manifested in a feeling of energy surge, in decreased sleeping period, however, without feeling fatigued, in increased libido (prior to that it was decreased on average). Insignificant transitory systolic arterial pressure increase (by 5–10mm Hg) was observed in some patients directly after tDCS. An increased level of sympathetic ANS activity is supposed to result in rebalancing of parasympathetic and sympathetic ANS. Due to this fact, among others, this localization in patients with symptoms of increased parasympathetic ANS activity is the most effective one. However, abrupt HA reduction during tDCS cannot be explained only by improvement of patient’s psycho-emotional condition. Alterations in brainstem reticular formation (RF) and, particularly, in mesencephalic RF during tDCS seem to play an important role in observed effects. Activating locations with similar low threshold for activation and inhibition reactions as in non-specific RF structures of mesencephalon and thalamus are revealed in different cortical areas (Penfield and Jasper, 1954; Andreyeva et al.,1979). Our results also suggest the possibility of targeted alteration in RF functional state by influencing the modulating cortical areas (Pinchuk, 2007).

Complaints between attacks point to a chronic dysfunction of hypothalamic system both in patients with migraine and in patients with TTH. Low tolerance for different provoking factors (low “migraine threshold”), also stress and vasodilator factors indicates the same. Improved hypothalamus functioning during tDCS manifests in normalization of patients.

Doctors are experimenting with tDCS to treat severe depression and help stroke victims regain their speaking skills. Students in theory could use it to solve math problems or pick up Chinese. Air Force researchers are using it to make people better at guiding killer drones, and DARPA has found it could improve snipers’ marksmanship.

Other noteworthy studies:

The facilitation of all subcortical neurons were potentiated by repeated applications of transcranial direct current stimulation (tDCS) and outlasted the polarization by at least 1-2 h, replicating tDCS effects on indirect activation of cortical neurons. The results indicate that the beneficial effects of tDCS on motor performance in humans may be due to more efficient activation of not only cortical but also subcortical neuronal systems. Combined actions of tDCS on cortical and subcortical neurons might thus further improve recovery of motor functions during rehabilitation after central injuries. 

The current from Transcranial Direct Current Stimulation (tDCS) is tiny - just 1 to 2 milliamps - and though the mechanism is not fully clear, tDCS appears to increase the excitability of neurons, making active areas of the brain work even harder. Depending where you place the electrodes (the different coordinates on the scalp and head where the electrodes are placed are known as a “montages”), it can lead to an enhancement in cognitive functions including attention and vision.

Roi Cohen Kadosh, a neuroscientist at the University of Oxford, is particularly interested in tDCS's potential to give our brains a boost. He has been looking for the part of the brain that is responsible for mathematical ability. In 2007, he pinpointed this to the right parietal lobe, just above the right ear. When his team "short-circuited" this area using transcranial magnetic stimulation (TMS) - a stream of magnetic pulses which temporarily disables a targeted area of the brain - they found that people got worse at numerical tasks. In fact, their performance resembled people with dyscalculia, who have difficulty comprehending mathematics.

Having disrupted our ability to use numbers, Cohen Kadosh wondered whether he could improve it too.

He now has his answer. Cohen Kadosh managed to improve numeracy in volunteers by applying tDCS to the right parietal cortex. He zapped his volunteers while they familiarized themselves with made-up symbols representing the numbers 1 to 9. The volunteers had no idea which symbols stood for which number but had to work it out by trial and error. After each training session they were given tests to see how well they could perform calculations using the symbols. Those given tDCS learned the symbols faster and did better in the tests than those given a sham procedure. It did not affect other brain functions, Cohen Kadosh's team found. Cohen Kadosh, who announced his results at a conference at the University of Oxford in June, had another surprise in store - the improvements have lasted six months so far.

Since we constantly encounter numbers in our daily life, Cohen Kadosh said it is really important that people who have difficulties with numbers know about these kind of options for improving their cognition, as an alternative to drug therapies.

Electricity can also boost visual memory. Richard Chi and colleagues at the University of Sydney, Australia, used tDCS to increase activity in the right anterior temporal lobe, near the temple, which is involved in visual perception and memory. His volunteers experienced a 110 per cent improvement in a subsequent visual memory task compared with a group who received a sham treatment (Brain Research, vol 1353, p 168).

It doesn't take a huge leap of imagination to see where this could all be heading. Cohen Kadosh reckons tDCS could be packaged into a portable gadget. "In the future I can see it being of use in schools or at home, to advance the abilities of children with learning difficulties." He says that it is much safer than other types of brain stimulation because tDCS does not cause neurons to fire directly, it merely makes them more responsive.

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