Transcranial electrical stimulation: definition and applications

A technique that allows us to stimulate some regions of the brain. We explain what it is used for.

One of the newest forms of therapy takes advantage of electromagnetic forces for the treatment of neuropsychiatric disorders, offering advantages that other forms cannot achieve. Through transcranial electrical stimulation (TES) of the brain it is possible to provoke changes that help to modify the brain and facilitate the therapeutic process. and facilitate the therapeutic process.

Let us see what we mean when we refer to transcranial electrical stimulation, what advantages it offers and in what possible areas this modern form of treatment could play a role.

What is transcranial electrical stimulation?

It is a procedure which, by means of very low electrical currents, manages to stimulate specific parts of the brain. As the name suggests, the procedure is transcranial, i.e. the currents are applied outside the skull without touching the patient. Contrary to most direct brain stimulation procedures where it is necessary to open the patient and his skull, transcranial electrical stimulation is a non-invasive technique. Because of this and because it is completely painless, it is a very promising and safe line of research.

The technique works as follows: through a pair of electrodes placed on the skull, a very weak electric current is applied directly to the brain for a few minutes. These currents generate an electric field that modulates neuronal activity. As we know, the activation or not of neurons is related to their depolarization, an electrical process that can be modified. In addition, the type of current used in the stimulation will have particular effects.

For example, it is known that through transcranial electrical stimulation with direct current, neurons alter their discharge rate, it is known that through transcranial electrical stimulation with direct current the neurons alter their discharge rate.. Depending on whether this is cathodic or anodic, the effects produce an increase or a decrease in this rate. These changes can last from minutes to hours after stimulation, depending on the stimulation parameters. What is certain is that direct current stimulation is capable of changing the performance of individuals in a Wide range of cognitive tasks.

Another form of transcranial electrical stimulation uses alternating current at random frequencies. Studies have found that the motor cortex, after being exposed for ten minutes to this type of current, becomes much more excitable. Thus, neurons in this area subjected to electric current are easier to activate and respond better to motor tasks. Similar effects have been found in other different areas of the brain, highlighting the potential applications for inducing brain plasticity and facilitating the rehabilitation of damaged or dysfunctional areas.

Advantages and disadvantages of this technique

Any therapeutic technique has its pros and cons.. The ideal when developing a technique, based on psychological or neurological principles, is to obtain the maximum benefit while minimizing costs and negative effects.

Although this technique is still in its infancy and it is too early to talk in a final way about its advantages and disadvantages, it is possible to make a first outline.

Advantages

The main positive aspect of transcranial electrical stimulation is that it is painless and noninvasive.. It is a unique procedure in the sense that it acts directly on neuronal function, unlike pharmacological interventions that must perform a series of steps before reaching the brain, without the need to open or introduce anything.

This opens up a whole range of therapeutic possibilities that would not be possible with traditional techniques. For example, frail elderly patients who do not tolerate medication well and are unable to take full advantage of cognitive rehabilitation can find in transcranial electrical stimulation an ideal complement to help re-stimulate those areas of the brain that are deteriorating without putting their health at risk.

The development of the technique also has very important theoretical implications for neuroscience. Transcranial electrical stimulation induces a kind of artificial brain plasticity, allowing researchers to manipulate this variable and experiment, ethically, with it. Thus, research in this line has a parallel development to research on neuronal plasticity, the cornerstone of cognitive rehabilitation.

Drawbacks

Rather than drawbacks, it would be more appropriate to speak of obstacles or difficulties.. The truth is that this is a recently developed procedure that does not yet have sufficient empirical support to understand how it works and how to get the most out of it. It is not clear what the exact relationship is between the applied current and the neurons in different brain areas. We do not know if all areas respond in the same way, if it is possible to maintain the changes over time, or if there is some kind of adverse effect.

The effects described as therapeutic are not yet powerful enough to constitute an alternative, nor have all the possibilities that electrical stimulation of the nervous system allows been explored. Also, it is likely that at this time the machines are too expensive and do not compensate for the reduced therapeutic benefit they produce. Therefore, in order to evaluate the feasibility of the treatment with its economic cost, it is necessary to explore the extent to which the therapeutic effects penetrate.

Areas of application

Transcranial electrical stimulation has been successfully used in the symptomatic treatment of various disorders such as Parkinson's disease, epilepsy and chronic pain.. However, greater benefits are obtained in the treatment of acute symptomatology after suffering neurological damage. For example, significant improvements have been achieved in symptoms such as spatial neglect after ischemia or trauma, improved naming ability in aphasia caused by vascular accidents, or recognition memory in patients with Alzheimer's disease.

These therapeutic successes reflect the fact that electrical stimulation enhances brain plasticity, making it of particular interest for the treatment of loss of neurocognitive functions due to atrophy or neurodegeneration. We think of dementia, neurocognitive disorders, vascular accidents, tumors and trauma as the most striking candidates for this type of therapy.