Developed as an answer to the problem of brain injuries and certain mental illnesses, tDCS has truly made an 180° turn, heading towards a place no one could have ever predicted. For decades, it has been used as a last resort to help patients suffering from mental illnesses. It has also proven to be a highly efficient method in helping stroke patients regain control over their mental functions, including walking and talking. But its recent application as a cognitive enhancer tool has created a stir in the field of neuroscience. In the attempt to pinpoint the exact effect tDCS has on our mental powers, we have to start from the beginning: the brain.
Your Brain in the Fast Lane!
Arguably the most complex organ in the human body, the brain has baffled scientists for centuries. Aside from a few things we have learned, like its size, shape and consistency, much about it is still unknown and undiscovered. The workings of the brain are still as much of a mystery as they were a hundred years ago. What we do know is that its founding blocks, impulse-conducted cells, make up only about 10% of it, and the glia (the glue that binds the neurons together) makes up as much as 90%. It all looks a lot like a highway, with millions and millions of lanes – pathways, each going in different directions. The pathways, or synapses, are the brain’s response to outer stimuli. These pathways get created whenever a person learns something new – a language, sport, how to tie a shoelace, etc. This superpower that our brain has of creating new synapses whenever we are exposed to new stimuli is something called plasticity, and it is directly proportional to the number of synapses the brain has. The more synapses there are, the higher the plasticity of the brain. How fast you learn a second language, master a new skill, solve a math problem, etc. depends not only on the number of neurons you have but also on your brain’s plasticity.
Some simple math here: number of neurons + brain’s plasticity = degree of intelligence
Studies have shown that the higher the number of neurons and synapses you have, the higher your IQ will be.
And while the number of neurons is not something we can change (it’s written in our genetics), the plasticity of the brain is actually something we can control – through constant stimulation, or being exposed to new situations, problems, and difficulties. This often requires quite a bit of effort, and, what’s even more important: time.
But, there seems to be a shortcut to the whole story, in the form of tDCS. An electrifying shortcut indeed!
tDCS as an outer stimulus
Studies conducted on tDCS have shown that stimulating a certain part of the brain through very low-level currents of up to 2mA, can cause an “excitability” of the brain in healthy individuals. This excitability of the brain is seen as a number of cortical changes that can last even after the stimulation is done. How long the changes last is directly linked to how long an individual has been exposed to a stimulus, the number of tDCS sessions, as well as the intensity of the stimulus.
There are two types of changes that tDCS can cause: depolarization or hyperpolarization. Namely, when the anodal tDCS is conducted, which is positive stimulation, the resting membrane potential depolarizes. This, in turn, increases the neuronal excitability and allows for more spontaneous cell firing. On the other hand, when cathodal tDCS is performed, which is negative stimulation, the resting membrane potential gets hyper-polarized, thus decreasing spontaneous cell firing, a.k.a. neuron excitability.
tDCS takes advantage of two concepts, LTP and LTD. Long-term potentiation (LTP) refers to the strengthening the connection between two neurons. LTD, or long-term depression, refers to the weakening of the same connection, thus causing the transmission between two neurons to be enhanced or hindered.
One of the studies conducted on a group of 60 participants researched the effects of tDCS on creativity. Test participants were given a number of everyday objects, such as a baseball bat, for which they needed to come up with another use (for example, using that bat as a rolling pin). Thinking about unconventional uses of simple everyday objects requires “thinking outside the box”, which requires thinking about the size and material of the object as well as eliminating the usual things that the object is used for. This all required a high level of creativity.
The participants were presented with 60 different objects, one every nine seconds. The researchers noted down the answers, the lack of answers, as well as the time it took the participants to come up with an answer.
The study showed that the participants who received tDCS to their left prefrontal cortex didn’t know 8 answers on average. Those who received placebo or tDCS to their right prefrontal cortex missed about 15 answers out of 60. The group whose left prefrontal cortex was inhibited through tDCS was also faster in coming up with the answers – a whole one second quicker than the other two groups, which is a lot when it comes to psychological research, as the director of Penn’s Center for Cognitive Neuroscience and lead researcher Sharon Thompson-Schill concluded.
Another study on the stimulation of the left dorsolateral prefrontal cortex in patients with depression showed that 48% of participants responded well to the treatment. They received tDCS every weekday, 30 treatments in total. A majority of them noted a substantial difference in their cognitive powers, i.e. better working memory and verbal fluency.
A number of studies suggest that tDCS may improve learning, vigilance, intelligence, and working memory. However, many of these studies have been small and heterogeneous, and meta-analyses have failed to prove conclusive effects, and long-term risks have not been established. Consequently, the F.D.A. does not regulate the use of tDCS.
A tDCS – DTC (direct-to-consumer) device consists of a main operating unit, one battery, and two electrodes: an anode and cathode with conductive sponges that can be applied to the head, held in place with a band. The principle behind it is to place the electrodes on brain regions of interest on the skull and let the low-level direct current induce intracerebral current flow which will either decrease or increase excitability of the neurons. The treatment lasts twenty to thirty minutes with the current level individually adjusted, but limited to a maximum of 2mA.
The specific placement of the electrodes is called a montage based on the “10-20 International System of Electrode Placement”. This is a mapping point for the brain with coordinates that point to specific regions of the brain. Montages vary, depending on what effects the individual would like to have. For a comprehensive list of possible montages as well as links to the studies conducted for various conditions, like mood improvement, accelerated learning, pain management, working memory improvement, etc. please check this article, which also contains brain electrode placement maps for your reference.
Should you or shouldn’t you?
Though tDCS has taken the world of neuroscience by storm, it is not the only place of its application. Scientists are not the only ones intrigued by it. Army and military forces are currently conducting many experiments in the hope that one day they’ll be able to create a “super soldier” – one with the heightened concentration, improved cognitive powers, and enhanced working memory.
So, the final question of whether to supercharge the brain or not is completely left to the reader, but with the benefits heavily outweighing the drawbacks, it seems only logical that there are many potential benefits to tDCS use.
One thing is for certain, tDCS should not be dismissed so easily! It is definitely one form of treatment that will shape our future.