Difference between revisions of "Transcranial direct-current stimulation"

From HCE Wiki - The Human Cognitive Enhancement Wiki
Jump to: navigation, search
(summary)
(added link to relevant projects)
Line 56: Line 56:
  
 
http://www.consciousnesshacking.org/about/
 
http://www.consciousnesshacking.org/about/
 +
 +
http://eu.foc.us/
  
 
== References ==
 
== References ==

Revision as of 10:29, 22 March 2016

A schematics showing how tDCS works.

Transcranial direct-current stimulation, tDCS in short, is a neoromodulatory technique in which a small and constant direct current is delivered through the skull in order to inhibit or excite neurons in the brain, that is to say to change the threshold at which the neurons will fire. tDCS may help patients suffering from strong depression and it may also relieve pain, help patients with neurodegenerative diseases, or enhance human cognition.[1]

It is possible, however, that tDCS have no effect on the actual cognitive performance as it has been found by a quantitative review of past tDCS studies in 2015.[2]

Main characteristics

The tDCS is done by putting two electrodes on the scalp and running weak direct current between them so the current passes through the brain. Different areas of the brain can be affected based on the position of the electrodes. Depending on whether the stimulation is anodal or cathodal, the neuronal resting membrane potential is either depolarized or hyperpolarized respectively. Anodal stimulation enhances excitability, while cathodal stimulation has opposite results. The efficacy of the technique closely depends on the strenght of the generated electrical field. Clinically, tDCS is usually administered via two sponge electrodes soaked in a saline solution for conductibility.[3][4]

The effects of tDCS can be long-lasting. Prolonged sessions result in after-effects that may last hours. This is due to the brain neurotransmitters and receptors having polar properties and as such they react to electrical fields which results in lasting neurochemical changes in the brain. tDCS has a lasting effect on NMDA receptors and intracortical and corticospinal neurons. This type of stimulation also influences non-neuronal components of the nervous system, such as vessels and connective tissues, and can influence the widening of the blood vessels in the brain.[1]

Historical overview

The ability of the electrical current to influence human cognition, especially the perception of pain, has been observer since the 48 CE by the Roman court physician Scribonius Largus. He observed that placing a live fish of the order Torpediniformes, able to deliver electric discharge of up to 220 V, can ease the pain of the headaches his patients suffered. Other great physicians such as Pliny the Elder, Claudius Galen, or Ibn-Sidah noted the beneficial effects of these animals in their works as well. The study of electric rays inspired Luigi Galvani and Alessandro Volta to experiment with the effects of electrical current on human physiology.[5] Galvani’s nephew Giovanni Aldini reported the successful treatment of patients suffering from melancholia.[6] He noted, after testing his device on himself first, that the stimulation is rather unpleasant and it's effects lasted for several days:

"First, the fluid took over a large part of my brain, which felt a strong shock, a sort of jolt against the inner surface of my skull. The effect increased further as I moved the electric arcs from one ear to the other. I felt a strong head stroke and I became insomniac for several days." - Giovanni Aldini, 1803[7]

Experiments with the DC stimulation continued until the 1930' when its usage was abandoned in favour of more reliable electroconvulsive therapy which, for a while, overshadowed the practice of brain polarization and later by the advances in pharmaceutics. However, the research into the effects of DC did not cease. From the 1960' and onward, there is a growing interest in this for of brain stimulation, with various papers reporting that there is indeed a measurable effect on the brain. These resulted in changes in mood and alertness. Nowadays, the practive of tDCS is being heavily researched.[5][8]

Purpose

Transcranial direct-current stimulation is a tool used to treat neuropsychiatric diseases and to influence human cognition without the use of invasive methods or pharmaceutics.[9]

Company & People

Important Dates

Enhancement/Therapy/Treatment

Ethical & Health Issues

http://www.nature.com/news/brain-doping-may-improve-athletes-performance-1.19534 (used as doping)

Public & Media Impact and Presentation

http://www.newyorker.com/business/currency/an-evening-with-the-consciousness-hackers

Public Policy

Related Technologies, Projects or Scientific Research

https://thebrainstimulator.net/research/

http://www.consciousnesshacking.org/about/

http://eu.foc.us/

References

  1. ↑ 1.0 1.1 BRUNONI, Andre Russowsky, et al. Clinical research with transcranial direct current stimulation (tDCS): challenges and future directions. Brain stimulation, 2012, 5.3: 175-195.
  2. ↑ HORVATH, Jared Cooney, FORTE, Jason D. and CARTER, Olivia, 2015, Quantitative review finds no evidence of cognitive effects in healthy populations from single-session transcranial direct current stimulation (tDCS). Brain Stimulation [online]. 2015. Vol. 8, no. 3, p. 535–550. DOI 10.1016/j.brs.2015.01.400. Available from: http://dx.doi.org/10.1016/j.brs.2015.01.400
  3. ↑ NITSCHE, M. A.; PAULUS, W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. The Journal of physiology, 2000, 527.3: 633-639.
  4. ↑ A., Antal, Paulus W. a Nitsche M.A., 2009. Principle and mechanisms of transcranial Direct Current Stimulation (tDCS). Journal of Pain Management [online]. roč. 2, č. 3, s. 249–257. Available from: http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=emed9&NEWS=N&AN=2010453470
  5. ↑ 5.0 5.1 PRIORI, Alberto, 2003, Brain polarization in humans: A reappraisal of an old tool for prolonged non-invasive modulation of brain excitability. Clinical Neurophysiology. 2003. Vol. 114, no. 4, p. 589–595. DOI 10.1016/S1388-2457(02)00437-6.
  6. ↑ PARENT, André, 2004, Giovanni Aldini: from animal electricity to human brain stimulation. The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques. 2004. Vol. 31, no. 4, p. 576–584. DOI 10.1017/S0317167100003851.
  7. ↑ Aldini G. Précis des expériences galvaniques faites récemment à Londres et à Calais par Jean Aldini […], suivi d’un extrait d’autres expériences, détaillées dans un ouvrage du même auteur, et qui ont été publiées à Londres par M. Nicholson. Paris: Levrault et Barrau, 1803.
  8. ↑ NITSCHE, Michael A., COHEN, Leonardo G., WASSERMANN, Eric M., PRIORI, Alberto, LANG, Nicolas, ANTAL, Andrea, PAULUS, Walter, HUMMEL, Friedhelm, BOGGIO, Paulo S., FREGNI, Felipe a PASCUAL-LEONE, Alvaro, 2008, Transcranial direct current stimulation: State of the art 2008. Brain Stimulation. 2008. Vol. 1, no. 3, p. 206–223. DOI 10.1016/j.brs.2008.06.004.
  9. ↑ A., Antal. W., Paulus. M.A., Nitsche. (2009). Principle and mechanisms of transcranial Direct Current Stimulation (tDCS). Journal of Pain Management, 2(3), 249–257. Retrieved from http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=emed9&NEWS=N&AN=2010453470
Retrieved from "http://hcenat.zcu.cz/wiki/index.php?title=Transcranial_direct-current_stimulation&oldid=2719"