Transcranial Direct Current Stimulation (tDCS) has roots in history going further back in time than most of us realize; to truly understand the rich history of tDCS, we’ve compiled a timeline of significant events in the developments toward tDCS technology.
3000 BC: Ancient Egyptians became aware of electrical properties of Nile catfish.
400 to 300 BC: Plato and Aristotle observe and record the torpedo fish’s (electric ray) ability to elicit therapeutic effects using electrical discharge.
43 AD: Roman physician Scribonius Largus, discovers and records pain relieving properties of electricity after studying a story of a man relieved of gout related pains after stepping on an electric ray. Scribonius would later use electric fish like the torpedo fish for headache treatment.
143 AD: Greek physician Claudius Galen realizes torpedo fish had to be alive when applied during treatment, implying the torpedo fish must be actively producing something that causes the pain relieving phenomenon (electric current!).
11th century: Muslim physician from Persia, Ibn-Sidah, suggests the use of torpedo fish as epilepsy treatment when applied to the brows of patients.
Persian polymath Avicenna and Andalusian philosopher Averroes uses torpedo fish as a means to headache and joint pain relief.
16th Century: Syrian physician Dawud al-Antaki uses torpedo fish to treat vertigo in his patients.
1660: German scientist Otto Von Guericke invents a hand cranked electrostatic generator, effectively creating the first controllable form of artificial electricity!
1745: Ewald Georg Von Kleist invents the first electric capacitor, dubbed the Leyden Jar.
1757: Experimenters and tinkerers like Anton de Haen and Benjamin Franklin uses electrostatic generators and Leyden jars for therapeutic electrification.
1756: Italian anatomist Leopoldo Marco Antonio Caldani uses the Guericke electrostatic generator to stimulate muscles in sheep and frogs; first evidence of the importance of electricity in physiology.
1767: Middlesex Hospital in England becomes the first hospital to purchase an electrostatic therapy machine.
1773: Anatomist John Hunter studies and elucidates the mechanism for the pain relief and numbing caused by the torpedo fish. Discovers torpedo fish actually produced electricity!
1780: Luigi Galvani and Alessandro Volta induced muscle twitching and movement in animals using an electrical current; more evidence toward the importance of electricity in animal physiology.
1800: Volta creates the first battery, which produced a direct current (DC). This opened the doors for the first clinical applications of therapeutic direct current stimulation.
1801: Galvani’s nephew Giovanni Aldini, uses an early form of tDCS to improve the mood of 27 year old farmer Luigi Lanzarini who presumably suffered from depression “Melancholia”. This was one of the first recorded instances of tDCS being used to treat neurological and psychiatric conditions, a major topic of interest in today’s medical fields.
1802: Hellwag and Jacobi observe the occurrence of phosphenes during tDCS applications.
1930-1940: Electroconvulsive therapy (ECT) quickly gains popularity and overshadows tDCS; persistent inconclusive results, a lack of understanding of operating principles and poor experimental design were several factors leading to the loss of interest in experimental tDCS at that time.
1960: tDCS regains its popularity as interest in electro-sleep therapy and electro-anesthesia increases, this leads to an increase in effort toward understanding how tDCS affects the brain.
1964-1966: DJ Albert publishes two major papers illustrating that tDCS could increase or decrease memory retention in rats, depending on current direction. This shows tDCS’ capability for modulating cortical excitability.
Around this time, Lippold and Redfearn also reports on anodal current’s ability to induce an increased alertness, mood and motor activity and cathodal current’s ability to induce quietness and apathy; providing further evidence to suggest tDCS’ ability to modulate cortical excitability.
1970: Advances in pharmaceuticals for psychiatric disorders captures public attention, consequently overshadowing electrical therapy research.
1998: Electrical stimulations regain interest due to an effort to develop more effective and targeted treatments with fewer side effects than tradition pharmacological means.
New brain imaging techniques and brain stimulation methods also help to reintroduce tDCS.
Progress in microcontroller technology allows engineers to create precision tDCS devices with superior control over stimulation parameters at reduced costs. Research is currently being conducted on tDCS as a means for treating neurological and psychiatric disorders, with applications in depression, schizophrenia, aphasia, addiction, epilepsy, chronic pain, attention and motor rehabilitation. Possible applications of tDCS on healthy individuals are also being explored for cognitive and neurological enhancements. Research is also being conducted in an effort to understand tDCS and its interactions with the brain on multiple levels. This is made possible by the advancements of computer processing capabilities and physics simulation software.
History of Transcranial Electric Stimulation. (n.d.). Retrieved from https://neurogal.com/history-of-transcranial-electric-stimulation/
Sarmiento, C. I., San-Juan, D., & Prasath, V. B. (2016). Letter to the Editor: Brief history of transcranial direct current stimulation (tDCS): From electric fishes to microcontrollers. Psychological Medicine,46(15), 3259-3261. doi:10.1017/s0033291716001926
Team, H. N. (2015, April 07). A brief history of tDCS. Retrieved from https://haloneuroblog.wordpress.com/2015/01/24/a-brief-history-of-tdcs/