Transcranial Direct Current Stimulation (or tDCS in English for simplified search) is a popular method of brain stimulation that is used to modulate the brain (for a deeper meaning we send a contact and we will send you individual studies), while facilitating or inhibiting effects on various kinds of behavior. Thanks to it, people are more attentive and prevent many brain disorders primarily in old age. It also leaves no clinically proven side effects and is a military-proven method for daily stimulation, thanks to which soldiers have increased concentration. In this article, we examine some of these differences and highlight the experimental parameters and reasons that may underlie their occurrence. We provide a general practical overview of the tDCS methodology, including what it is used for, how to use it, and considerations for designing an effective and safe solution. Our goal is to equip people new to tDCS with the basic knowledge to make informed and well-rounded decisions. By summarizing different approaches, stimulation parameters, and outcomes, this article should help inform future tDCS research in various fields.
Enhancing human cognitive processes has long been a focus of scientific experimentation, and transcranial direct current stimulation (tDCS) has recently come to the fore as a promising tool for modulating cognitive and motor skills (Nitsche and Paulus, 2000). The technique has grown in popularity over the past decade, as exemplified by a PubMed search, which returned 1,500 published articles containing the phrase “tDCS” between 2011 and 2015, compared to only 65 published between 2000 and 2005. tDCS involves increasing the concentration of weak electrical current, traditionally by placing two electrodes attached to the participant’s scalp. In this traditional, unihemispheric tDCS setup, one electrode is known as the target electrode and the other as the reference electrode. Some mounts place the reference electrode extracephalically, for example on the upper arm. Alternatively, electrodes can be placed “bihemispherically” to deliver dual stimulation to two parallel cortices (eg, parietal cortices – Benwell et al., 2015). This refers to the deliberate upregulation of one brain region while downregulating another (Lindenberg et al., 2010). It is also now common to use several smaller electrodes instead of one target and reference electrode).
During stimulation, a current flows between the electrodes and passes through the brain. It is generally believed that a positive anodal current temporarily facilitates behavior associated with the cortical area below the target electrode, whereas a negative cathodal current inhibits the behavior (Nitsche et al., 2008). Similar to transcranial magnetic stimulation (TMS), active stimulation can be compared to a sham protocol (see What is a sham condition?). The direction of current flow distinguishes anodal and cathodal stimulation by modulating the resting membrane potential of stimulated neurons ( Nitsche and Paulus, 2000 ). Anodal stimulation depolarizes neurons, increasing the likelihood of action potentials, while cathodal stimulation hyperpolarizes neurons, decreasing the likelihood of action potentials (Nitsche et al., 2008). These polarity-specific effects have been demonstrated in several cases (Antal et al., 2003; Priori, 2003) both during (online) and after stimulation (offline) (see What are the differences between online and offline designs?).
What is tDCS?
tDCS is a non-invasive method that allows reversible modulation of activity in specific areas of the brain. This has provided a valuable tool for establishing brain-behavior relationships in a variety of cognitive, motor, social, and affective domains (for a review, see Filmer et al., 2014), and has been shown in healthy populations to temporarily modify behavior, accelerate learning, and enhance task performance (Coffman et al., 2014; Parasuraman and McKinley, 2014). For example, anodal stimulation has been shown to improve facial expression recognition (Willis et al., 2015) or inhibit aggressive responses (Dambacher et al., 2015; Riva et al., 2015), while cathodal stimulation promotes implicit motor learning when stimulating the dorsolateral prefrontal cortex by suppressing working memory activity (Zhu et al., 2015). From a practical point of view, the device is reusable, relatively inexpensive, and can be easily replaced if worn or damaged. This adds to its therapeutic potential in the clinical sciences—it is easy for researchers or patients to administer tDCS at home, and it may soon be used alongside (or as a substitute for) drug therapy to speed recovery and improve motor and cognitive performance (Brunoni et al., 2012). . In fact, tDCS has even been successfully applied to reduce depressive symptoms (Fregni et al., 2006; Nitsche et al., 2009), although further expansion is needed to support its use for this purpose. In small studies, it has been shown to reduce hallucinations in people with schizophrenia (Agarwal et al., 2013) and improve syntax acquisition delay in autism spectrum disorder (Schneider and Hopp, 2011).
How is tDCS used?
Conducting a stimulation session
Here we describe a standard tDCS setup using a target and reference electrode. First, it is necessary to determine the desired locations where the electrodes will be placed (for more details on localization techniques, see the section Locating electrode placements). Before attaching the electrodes to the scalp, the experimenter should make sure that the skin is not damaged. If saline is used as the conductive agent, the electrodes can be placed in sponge bags, and soaked so that they are sufficiently moist but not dripping. Increasingly, however, conductive paste or EEG gel is used to attach electrodes to the scalp, which can regulate current distribution more effectively than saline. The participant’s hair should be parted to ensure good contact between the scalp and the electrode. The saline solution should not run down the scalp or spread through the hair. The electrodes are then connected to the stimulator using wires connected to the corresponding anode/cathode ports. When the electrode is placed over the target area, it should be secured with a cap, rubber bands, or elastic tubular mesh. The reference electrode should then be secured in the same way.
After connecting the electrodes, it is necessary to program the duration of the stimulation, the intensity of the current and the rise/fall times. Some stimulators allow the experimenter to preprogram the stimulation parameters, while others require manual input before each session. It is important to monitor the participant during stimulation, including simulated conditions, to ensure that they do not experience discomfort. It is also important to check the levels displayed on the stimulator to ensure that the pacing has not failed. Reliable and consistent application of tDCS requires good scalp contact to maintain conductivity. High levels are an indicator of poor conductivity and may be the result of a poor electrode setting. Because the levels emphasize whether the current can remain constant, it is important to monitor these levels displayed on the stimulator during the experiment. High levels may be the result of the inadequate parting of the hair to allow good contact with the scalp or a lack of conductive material between the scalp and the electrode. DaSilva et al. (2011) recommend keeping levels below 5 k ohms. Stimulation failure can therefore be resolved by reapplying saline to the capture bags or by sufficiently dividing the hair under the electrodes.
So where can I try a tDCS device?
Contact us. It’s that simple. Our offices are equipped with all the devices that are currently available on the market and thanks to this we can provide you with the best care. In addition to our own, we have state-of-the-art research equipment from the United States, Slovenia, the United Kingdom, and Asia.
Anyone who has ever suffered from a concentration disorder or more serious cognitive problems should definitely try the device. thanks to it, people can get the most out of their mental capacity, all without side effects. Yes, the device is a bit impractical and sometimes it is more difficult to imagine wearing such a headband at work. But whether you are an entrepreneur, a production manager, or a student, a little boost will certainly not hurt you, thanks to which your mind will not be stunted and you can enjoy a full life in old age.