Does neurostimulation with tDCS affect everyone in the same way?

As you probably know by now, your PlatoWork headset functions by creating an electrical field across your brain that can change your thoughts, ideas, concentration and how you learn. What you may not know is that how the stimulation affects your brain is somewhat unique to you.

The effects of neurostimulation differ from person to person because just like fingerprints, our brain is unique. When writing this article, I used a combination of PlatoWork's Learn and Create mode. Learn during background research and Create for writing.

Keep reading to find out why neurostimulation affects our brains differently.

How does tDCS affect the brain?

The tDCS technology in a PlatoWork headset affects your brain by up regulating and down regulating neural activity levels in certain areas of your brain, depending on what mode you have chosen in the app. 

PlatoWork uses a direct current to stimulate the brain, which means that current continuously flows in one direction from one electrode, through the brain, to the other electrode. The traditional explanation of how the current affects brain activity is based on animal studies. 

Where the current enters the brain (positive current) there is an up-regulation of brain activity and where the current exits the brain (negative current) there is a down-regulation of brain activity. 

Why does this happen? The current can change brain activity because a positive current causes a depolarisation of the cell membrane, which brings neural cells closer to their firing threshold. When a neuron sends a signal we say that it ‘fires’ because it creates a short burst of electricity. On the other hand, a negative current causes a hyperpolarisation, which makes it harder for neurons to ‘fire’. All in all, this means that tDCS can turn neural activity up or down in the target brain areas, kind of like a volume button.

Both neurophysiological and cognitive levels come into play

The above is a very simplified explanation and today we know that it is much more complicated particularly because many individual factors affect how the current runs through the brain and how the brain is affected by it.

In fact, more and more studies have shown that the specificity in how the brain is affected by neurostimulation varies widely between individuals both on a neurophysiological and on a more cognitive level. The term cognition refers to all higher order mental processes such as perception, attention, predictions, planning, memory, learning, imagination, thought, emotions, etc.

The exact reasons are not fully understood as this is not caused by one single factor, but by many complex factors in concert. The most important ones are briefly described below. 

How much of the current reaches the brain?

First of all, when your headset creates an electric field across your head it is actually just a small portion of the current that reaches the brain. 

From the headset electrodes, the current has to pass through the skin, skull and cerebrospinal fluid, which is the fluid that surrounds the brain and spinal cord. Because we all have different shaped heads, skin type, skull thickness, brain size, etc., there are individual differences in how much of the current that reaches the brain. The good news is that only a small amount of current is needed to affect neural firing and neuroplasticity. 

The outer layer determines the neuron’s direction in the current flow

Probably the most important difference caused by brain anatomy is the individual differences in how the outer layer of the brain is folded because the folding pattern determines the physical direction that each neuron has within the current field. 

This is important because the direction a neuron faces, when current flows through it, determines to what extent that neuron is activated or deactivated. The same neuron could be activated in one person and deactivated in another. This may be one of the reasons why cognitive effects are sometimes reversed in some people.

Brain State 

More recent research has shown that cognitive effects from neurostimulation are also influenced by a person's neural brain state before starting a stimulation. Also here, the exact reasons are not fully understood but research has shown that how a person responds to stimulation is often modulated by how good they are at the underlying task. 

This is not just a matter of whether you are a novice or an expert at a task, even fluctuations in brain state during the day within the same individual has a measurable effect. This means that the effect you get from stimulation may not be the same if you stimulate in the morning or contra if you stimulate in the evening. Last but not least, the dose-response also varies widely between individuals.

Experiment until you find your optimal ‘mind tune’

Even if we apply the same current there are substantial differences in how much current reaches the brain and the resulting current-brain flow pattern is not the same from person to person. This means that neurostimulation does not work the same way in everyone and there is a difference in how a person responds to the stimulation. It is therefore important that you experiment with your headset. Try out all of the different modes and see how they work for you. 

If one mode does not work for a certain task, try another and try different current settings. Maybe the best scenario for you is to use it in the morning to get into the right work mindset or perhaps it is best for you to use it at the end of a long day when you need that extra boost. The point is that you should not stop experimenting until you find your mind tune.