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Transcranial Electrical Stimulation (tDCS, tACS and tRNS)

tDCS (transcranial Direct Current Stimulation), tACS (transcranial Alternating Current Stimulation) and tRNS (transcranial Random Noise Stimulation) arenon-invasive brain stimulation techniquesthat use electrical currents to modulate neuronal activity. Although they share similarities in their application, each of these techniques is characterized by differences in the nature of the currents used and the therapeutic objectives.

  1. tDCS (Transcranial Direct Current Stimulation): tDCS applies a constant, direct electrical current through two electrodes placed on the scalp. This currentmodulates neuronal excitability, increasing or decreasing it, depending on the polarity of the electrodes (anodal or cathodal). tDCS is used in the treatment of various conditions, such as depression, anxiety, chronic pain, and improving cognitive performance.

  2. tACS (Transcranial Alternating Current Stimulation): tACS uses an oscillating electrical current, instead of a constant current as in tDCS. This technique focuses onsynchronize or desynchronize neuronal oscillations at different brain frequencies (alpha, beta, gamma, etc.) to influence specific cognitive and emotional functions. tACS has been investigated in the treatment of disorders such as Parkinson's, epilepsy, and memory improvement.

  3. tRNS (Transcranial Random Noise Stimulation): tRNS applies an electrical current of varying amplitude and frequency in a random manner. It is believed that this techniqueincreases neuronal plasticity and cortical excitability, which may improve cognitive performance and recovery after brain injury. tRNS has been investigated in the treatment of depression, chronic pain, and improving cognitive performance, although its clinical application is less extensive than tDCS and tACS.


In summary, although these techniques share similarities in their application, they differ in the nature of the electrical currents used and their therapeutic objectives. Choosing the appropriate technique depends on the specific condition being treated and the professional's knowledge in the area.

These techniques use two electrodes that are placed on the patient's scalp: an anode electrode and a cathode electrode. Electrical current flows from one electrode to another through the brain, generating a polarizing effect that modulates neuronal excitability. The anodal electrode is placed over the area of the brain to be stimulated, while the cathode electrode is placed in a reference area.

tDCS is applied for a period of time that can vary from a few minutes to several hours, depending on the application. tDCS may have aimmediate effect in neuronal excitability, but may also haveLong-term effectsin brain plasticity, which is the brain's ability to change and adapt.

In terms of safety, tDCS is generallysafe and well tolerated. The most common side effects are mild and temporary, such as itching, tingling, or pain at the stimulation site. In rare cases, more serious side effects may occur, such as seizures or severe headaches. Therefore, tDCS should be performed bytrained professionalsand in a suitable environment.

In summary, tDCS is a non-invasive brain stimulation technique that uses low-intensity electrical current to modulate neuronal excitability in the brain. tDCS is used to treat different neurological disorders and is expected to be increasingly used in the future to treat a variety of neurological disorders and to improve cognitive and emotional function.

Diseases where tDCS has been applied:

  • major depression

  • Bipolar disorder

  • Anxiety disorders (such as obsessive-compulsive disorder, post-traumatic stress disorder, generalized anxiety disorder)

  • Schizophrenia

  • Chronic pain

  • Migraine

  • Parkinson's disease

  • Autism spectrum disorders (ASD)

  • Attention deficit hyperactivity disorder (ADHD)

  • Epilepsy

  • traumatic brain injury

  • stroke

  • Multiple sclerosis

  • Fibromyalgia

  • Eating disorders (such as anorexia nervosa, bulimia nervosa)

  • Addictions (for example, tobacco addiction, alcohol addiction)

It should be noted that this list is not exhaustive and that TMS and tDCS are being researched and developed to treat an even broader range of neurological disorders.

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