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Electrical Brain Stimulation to Treat Neurological Disorders
Published in Bahman Zohuri, Patrick J. McDaniel, Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
Bahman Zohuri, Patrick J. McDaniel
In particular, as depicted in Figure 6.9, the TES technique7,9 involves the application of weak electrical currents (∼1–2 mA) directly to the head for several minutes (∼5–30 minutes). The stimulation is delivered by a battery-driven current stimulator through a pair of electrodes. These currents generate an electrical field that modulates neuronal activity according to the modality of the application, which can be direct (transcranial Direct Current Stimulation, tDCS), random noise (transcranial Random Noise Stimulation, tRNS) or alternating (transcranial Alternating Current Stimulation, tACS). TES induces a polarization that is too weak to elicit action potentials in cortical neurons. However, it effectively modifies the evoked cortical response to afferent stimulation as well as the postsynaptic activity level of cortical neurons, presumably by inducing a shift in intrinsic neuronal excitability (as shown in tDCS studies on animals).45,46
Transcranial Magnetic and Electric Stimulation
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
Shoogo Ueno, Masaki Sekino, Tsukasa Shigemitsu
Depending on mainly the waveform of current, there are three methods of TES: tDCS, transcranial alternating current stimulation (tACS), and a special form of tACS, transcranial random noise stimulation. These technologies are considered well tolerated and operated (Kadosh, 2014). tDCS uses a DC in two forms depending on the direction of applied current: anodal tDCS and cathodal tDCS. Here, we mention the basics of tDCS because tDCS is widely used among the TES techniques.
Learning while multitasking: short and long-term benefits of brain stimulation
Published in Ergonomics, 2018
B. Frank, S. Harty, A. Kluge, R. Cohen Kadosh
Transcranial random noise stimulation (tRNS) is a variant of tES that has only been employed in a limited number of studies to date, but emerging evidence suggests that tRNS produces greater cortical excitability, neuroplastic change and learning effects compared to more well-known tES methods (Fertonani, Pirulli, and Miniussi 2011; Terney et al. 2008). With tRNS, the intensity and the frequency of the alternating current vary in a randomized manner within specified ranges. The effects of tRNS, at least when applied within the 1–2 mA range, are believed to be excitatory at both electrode sites due to its fast-oscillating field that putatively depolarizes neurons irrespective of the polarity of current flow (Terney et al. 2008). It can accordingly be bilaterally applied to the dorsolateral prefrontal cortex (DLPFC) to increase excitability simultaneously in both left and right DLPFC regions (Snowball et al. 2013), which are known to be important for learning and memory formation (Anderson 2005; Chein and Schneider 2012). tRNS has been shown to modulate neural excitability and neuroplasticity when applied over the DLPFC to support retention over mid-term and long-term periods (Snowball et al. 2013; Cappelletti et al. 2013). Previous studies have suggested that one of the mechanisms through which tRNS may achieve its functional effects is stochastic facilitation (Fertonani and Miniussi 2016; van der Groen and Wenderoth 2016). Stochastic facilitation is the term used to describe the general phenomenon whereby adding an appropriate level of random noise to non-linear systems can enhance the output of subthreshold signals (McDonnell and Ward 2011).