The History of Transcranial Direct Current Stimulation (tDCS)
Unveiling the Fascinating History of Transcranial Direct Current Stimulation (tDCS): A Timeline of Developments
Explore the captivating roots of Transcranial Direct Current Stimulation (tDCS) that extend far back into history, surpassing our common knowledge. To grasp the rich tapestry of tDCS’s evolution, we’ve meticulously compiled a timeline of pivotal events leading to the advancements in tDCS technology.
Ancient Egyptian Discovery (3000 BC):
Even in 3000 BC, the astute Ancient Egyptians were already aware of the electrical properties exhibited by the Nile catfish.
Plato and Aristotle’s Observations (400 to 300 BC):
The eminent philosophers Plato and Aristotle meticulously documented their observations of the therapeutic effects derived from electrical discharge by the torpedo fish (electric ray).
Roman Physician’s Revelation (43 AD):
Roman physician Scribonius Largus made an astounding discovery of the pain-relieving properties of electricity. Studying an account of a man relieved of gout-related pains after stepping on an electric ray, Scribonius recognized the potential of electric fish, such as the torpedo fish, in headache treatment.
Galen’s Realization (143 AD):
In 143 AD, Greek physician Claudius Galen uncovered a crucial insight into torpedo fish treatments. He deduced that the fish had to be alive during application, implying an active production of the pain-relieving phenomenon – electric current!
Medieval Explorations (11th Century):
During the 11th century, a prominent Muslim physician from Persia, Ibn-Sidah, suggested the use of torpedo fish as a treatment for epilepsy when applied to patients’ brows. Additionally, Persian polymath Avicenna and Andalusian philosopher Averroes utilized torpedo fish to alleviate headaches and joint pain.
Medical Advancements in the 16th Century:
In the 16th century, Syrian physician Dawud al-Antaki harnessed torpedo fish to treat vertigo in his patients.
The Birth of Electrostatic Generators (1660):
A significant breakthrough came in 1660 when German scientist Otto Von Guericke invented the hand-cranked electrostatic generator, a groundbreaking advancement that marked the first controllable form of artificial electricity.
The Leyden Jar’s Invention (1745):
Ewald Georg Von Kleist’s groundbreaking invention of the first electric capacitor, known as the Leyden Jar, furthered the understanding of electricity’s potential.
Electrostatic Therapy Applications (1757):
Pioneering experimenters like Anton de Haen and Benjamin Franklin harnessed electrostatic generators and Leyden jars for therapeutic electrification.
Electrifying Discoveries in Physiology (1756-1767):
In 1756, Italian anatomist Leopoldo Marco Antonio Caldani used the Guericke electrostatic generator to stimulate muscles in sheep and frogs, providing the earliest evidence of electricity’s importance in physiology. In 1767, Middlesex Hospital in England acquired an electrostatic therapy machine, making it the first hospital to do so.
Galvani, Volta, and Animal Physiology (1780):
Luigi Galvani and Alessandro Volta made groundbreaking progress by inducing muscle twitching and movement in animals using electrical current. This further solidified the significance of electricity in animal physiology.
The Birth of the Battery (1800):
In a monumental milestone, Volta created the first battery, generating a direct current (DC) and paving the way for the first clinical applications of therapeutic direct current stimulation.
tDCS for Neurological and Psychiatric Conditions (1801):
In 1801, Galvani’s nephew, Giovanni Aldini, employed an early form of tDCS to improve the mood of a 27-year-old farmer named Luigi Lanzarini, who was presumed to suffer from depression. This marked one of the earliest recorded instances of tDCS being used to treat neurological and psychiatric conditions, laying the foundation for its relevance in today’s medical field.
Notable Observations (1802-1930):
In 1802, Hellwag and Jacobi observed phosphenes during tDCS applications, revealing further intriguing aspects of the therapy. Subsequently, during the 1930s, Electroconvulsive therapy (ECT) gained popularity and overshadowed tDCS due to various factors, including inconclusive results and a lack of understanding.
tDCS Resurgence (1960s):
The 1960s witnessed the rekindling of interest in tDCS, coinciding with the rise of electro-sleep therapy and electro-anesthesia. This resurgence spurred heightened efforts to comprehend how tDCS influences the brain.
Major Discoveries in the 1960s (1964-1966):
DJ Albert published two significant papers highlighting tDCS’s capacity to enhance or diminish memory retention in rats based on the direction of the current. Around the same time, Lippold and Redfearn reported that anodal current induced increased alertness, mood, and motor activity, while cathodal current led to quietness and apathy, providing further evidence of tDCS’s ability to modulate cortical excitability.
Advances and Modern Relevance (1970-2000-Present):
In the 1970s, advances in pharmaceuticals for psychiatric disorders diverted attention from electrical therapy research. However, in 1998, electrical stimulations experienced a resurgence as researchers sought more effective and targeted treatments with fewer side effects than traditional pharmacological means. Furthermore, new brain imaging techniques and stimulation methods reintroduced tDCS, making it a focal point of research for treating neurological and psychiatric disorders, depression, schizophrenia, aphasia, addiction, epilepsy, chronic pain, attention, and motor rehabilitation.
The Technological Leap (2000-Present):
Progress in microcontroller technology revolutionized tDCS devices, allowing engineers to create precision devices with superior control over stimulation parameters at reduced costs. Presently, research is actively ongoing to explore tDCS applications for cognitive and neurological enhancements in healthy individuals, as well as understanding its interactions with the brain on multiple levels, facilitated by advancements in computer processing capabilities and physics simulation software.