Transcranial electrical stimulation: definition and applications

One of the newer forms of therapy takes advantage of electromagnetic forces for the treatment of neuropsychiatric disorders, providing benefits that other forms cannot. Through transcranial electrical stimulation (TSE) of the brain, it is possible to make changes that help modify and facilitate the therapeutic process.

Let’s take a look at what we mean by transcranial electrical stimulation, what benefits 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, thanks to very weak electrical currents, manages to stimulate specific parts of the brain. As the name suggests, the procedure is transcranial, meaning that currents are applied from outside the skull without touching the patient. Unlike most direct brain stimulation procedures where it is necessary to open the patient and their skull, transcranial electrical stimulation is a non-invasive technique. For this reason 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. With these currents, an electric field is generated which modulates neuronal activity. As we know, the activation or not of neurons is linked to their depolarization, an electrical process which can be modified. In addition, the type of current used in stimulation will have particular effects.

For example, it is known that thanks to transcranial electrical stimulation with direct current, neurons modify their rate of discharge. Depending on whether it is cathodic or anodic, the effects increase or decrease. These changes can last from a few minutes to a few hours after stimulation, depending on the settings of the same. What is certain is that direct current stimulation is capable of altering the performance of individuals in a wide range of cognitive tasks.

Another form of transcranial electrical stimulation uses alternating current at random frequencies. There are studies that show that the motor cortex, after being exposed for ten minutes to this type of current, becomes much more excitable. Thus, the neurons of this zone subjected to the 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 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 advantages and disadvantages. The ideal when we develop a technique, based on psychological or neurological principles, is to derive maximum benefit from it while minimizing costs and negative effects.

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

benefits

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

This opens up a whole range of therapeutic possibilities which, thanks to traditional techniques, could not be used. For example, frail elderly patients who do not tolerate medication well and do not take full advantage of cognitive rehabilitation may find transcranial electrical stimulation an ideal complement to help re-stimulate deteriorating areas of the brain without risking their health.

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 experimentally, to the extent of ethics, with it. Thus, research in this line is developing in parallel with research on neuronal plasticity, the cornerstone of cognitive rehabilitation.

disadvantages

Rather than disadvantages, it would be more appropriate to speak of obstacles or difficulties. The truth is, this is a recent developmental procedure that does not yet have enough empirical support to understand how it works and how to get the most from it. It is not known what the exact relationship is between the applied current and neurons in different areas of the brain. We don’t know if all areas react the same, if it is possible to keep the changes over time, or if there is some kind of side effect.

The effects qualified as therapeutic are not yet powerful enough to constitute an alternative and all the possibilities that electrical stimulation of the nervous system allows have not been explored. It is also likely that at this time the machines are too expensive and will not compensate for the reduced therapeutic benefit they produce. Therefore, in order to assess the viability of the treatment along with its economic cost, it is necessary to explore how far the therapeutic effects penetrate.

Application areas

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

These therapeutic achievements reflect that electrical stimulation improves cerebral plasticity, it is therefore of particular interest for the treatment of the loss of neurocognitive functions due to atrophy or neurodegeneration. We consider dementias, neurocognitive disorders, strokes, tumors and trauma to be the most prominent candidates for this type of therapy.

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