Beginners guide to tdcs created by: viktorija

tDCS, what?

Not exactly a novel technology, nor a nootropic, transcranial direct-current stimulation (tDCS) is a non-invasive and non-pharmacological form of brain stimulation that provides a constant low level of electrical current to an area of the brain.


Intro to tDCS

The futuristically sounding and cognitive abilities boosting method has existed for over a hundred years. Surprisingly, the method has regained the curiosity of researchers and biohacking community only recently. Today researchers hope to develop tDCS therapies that would be more effective than traditional chemical. At the same time huge number of companies are producing wearable consumer devices able to put the user in any mood. What should sound most surprising is that DIY hobbyists are building full devices from scratch.

A quick pubmed title search for tDCS reveals that there are over a thousand scientific studies published in peer-reviewed journals [R]. Many of the studies are suggesting the positive effects of tDCS. The effects are ranging from treating a spectrum of psychiatric disorders and for enhancing everything from creative problem solving to the acquisition of motor skills.


But, how does it work?

To unpack this advanced sounding technology, transcranial means passing through the skull, the direct-current tells it’s about a unidirectional flow of electric charge. And stimulation means it is stimulating the activity of the brain. We’ll learn later that the stimulation works in two ways, by exciting or depressing the neuronal activity. 


Electricity and neuronal activity

The mechanism of action of tDCS is reasonably easy to understand. It wouldn’t be inaccurate to reason by the logic that if the brain runs on electricity, then in the process of applying more electricity it should create an extra energy that would allow it to perform faster.

It's true that tDCS primarily works through brain’s electricity. The stimulation modulates brain function by causing the neuron’s membrane potential to change in either of the two ways - to depolarize or hyperpolarize. The depolarization is achieved by applying a positive stimulation or otherwise known as the anodal tDCS. The hyperpolarization is caused by delivering the negative stimulation (or cathodal tDCS).

What depolarization does to the neuron is it increases the excitability of it and enhances a more spontaneous firing of the cell. The opposite effect occurs during the hyperpolarization process, this is when the excitability of the neuron decreases. 


Neuroplasticity

One of the most striking and important features of tDCS is that the cortical changes are present even after the stimulation has ended. How long the changes will last depends on the intensity and duration of the stimulation session. 

Because it’s not possible that the brain remembers the electrical current for hours after the stimulation, there should be a chemical process involved. And there is - the depolarization and hyperpolarization are the mechanisms of action that brings up the concept of neuroplasticity.

Neuroplasticity, also known as brain plasticity, means a brain’s ability to change throughout the human’s life. This term gained popularity only in the second half of the 20th century when new research proved that the brain can be altered and trained even into adulthood. 

Using tDCS and alternating the synaptic transmission during depolarization and hyperpolarization two things are achieved, long term potentiation and long term depression. What these terms describe respectively is the strengthening or weakening of the connection between two neurons, resulting in a more plastic brain. 

tDCS works through the biochemical brain pathways and the one key molecule involved is called BDNF (brain derived neurotrophic factor). So when the brain is stimulated using tDCS, it starts making BDNF, and it is known that BDNF is a neuromodulator which enhances all processes involved in learning [R].


tDCS throughout the century

Brain stimulation using electricity might sound cutting-edge, but tDCS has a surprisingly long history. Originally the tDCS technology was developed to treat patients with psychiatric disorders or brain injuries. The very basic design of tDCS has been created over 100 years ago
There have been a number of basic experiments testing the animal and human electricity done even before the 19th century. Luigi Galvani and Alessandro Volta were the first two researchers that utilized the technology of tDCS to research animal cell electricity [R]. They started the clinical application of direct current stimulation in 1804, when Aldini successfully treated patients with depression. However, the invention of electro-convulsive therapy in the 1930s led to the loss of interest in tDCS. 

By the 1960s, tDCS had a comeback in popularity, and scientists began to systematically investigate its effects. During that time two influential papers were published by D. J. Albert in 1966 [R], showing that tDCS of the rat’s medial cortex enhanced memory consolidation. Despite this comeback of interest, the method of tDCS was once again forgotten because of the progress made in treating psychiatric disorders by pharmaceutical drugs. 

It is only until recently that electrical stimulation regained the curiosity of researchers and physicians who hope to develop more effective tDCS therapies than traditional pharmacological. Studies of brain mechanisms such as fMRI resulted in more understanding about the safety, showing evidence of relatively minor adverse effects in healthy humans and patients with neurological disorders [R].


Can I build it myself?

It's very easy to build a tDCS machine for about $20 with the right know-how. Just by going to the hardware store and doing some really simple shopping. You would need to get a battery, some sponge, salt and wires to connect everything together. Using these parts together you make electrodes and then by using some neuroanatomy reference and knowing what cognitive function you want to enhance, apply the electrodes on the brain region of interest. Some control software can also be used to regulate the duration and intensity. You can also find wide range of useful montages published online [R] for electrode placement. Supra Orbital is the most frequently used montage for depression and pain reduction.


The DIY tDCS movement

There is a widespread appeal of tDCS as relatively safe, cheap and effective. It has been met with enthusiasm by journalists, academics, and private individuals, hoping to purchase or construct the set for home use. These devices can be easily bought online without regulation.

Because tDCS device is relatively easy to make and cheap to acquire, there has arisen a movement where people stimulate their own brains with tDCS outside of research or medical environments. Since so many individuals who identify with the DIY tDCS movement purchase ready-made, direct-to-consumer (DTC) devices, [R], the border between DIY and DTC has become thin. There are many home use tDCS discussion groups online, such as Reddit forum dedicated to DIY tDCS [R].


Consumer tDCS

After a quick google search you can find an online store where it's possible to buy a tDCS device on a mere $200. Few companies (among the many) to mention that produce wearable tDCS are foc.us and Thync. The foc.us device, which was released in the summer of 2013, was arguably the first true direct to consumer tDCS device.

The other product to mention is Thync. Thync is interesting, because it’s not a strictly tDCS device. It uses a "blend” of technologies, tDCS and TENS (transcutaneous electrical nerve stimulation). The company released its device which is controlled via smartphone and provides a form of brain stimulation for mood alteration purposes, which allows the consumer to choose from a menu of so called vibes - physical energy, mental alertness, calm, or even euphoria.

Going more technical, the way Thync’s technology differs from strict tDCS is that they use a proprietary pulse scheme, producing different frequency and amplitude modulation for the calm and energy that stimulate the trigeminal nerve.

Going even more technical, by intercepting the requests between iPhone and Thync server we were able to find out how Thync’s vibes work. By reverse engineering how Thync works my DIYer hacker friend was able to develop his own vibe for Thync.

Other thing we found out by reverse-engineering Thync are the API names of many more unimplemented mood and mind enhancing methods. Which says that the company had ideas about implementing many more mood enhancing functions.


Brain enhancement faster and without pharmaceuticals? 

It is easy to build a complete tDCS machine from scratch for under a mere $20. An example home use would be using the cathodal stimulation (depolarization process) for treating psychological disorders caused by hyper-activity of a region of the brain [R]. This could possibly treat inattention and specifically ADHD. So by using the jumper cables for the brain, (while not specifically encouraging it), you might be able to stop using your Adderall or Vyvanse.

Unsurprisingly,the use of tDCS outside of research settings has not been well received by scientists, many of whom believe that home users may ruin it for the entire academic field [R].

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