From Faraday to modern neuromodulation: the history of transcranial magnetic stimulation
A journey through the milestones that led from electromagnetism to modern brain stimulation protocols.
Transcranial magnetic stimulation (TMS) brings together nearly two centuries of discovery. Its history begins long before neuroimaging and today's devices existed: it starts with a basic question about the relationship between magnetism and electricity.
1831: the physical basis
Michael Faraday described electromagnetic induction in 1831. The discovery showed that a changing magnetic field can generate an electrical current. Many years later, that principle would become the physical basis for magnetic stimulation of the nervous system.
Throughout much of the 19th and 20th centuries, there were experiments with electricity and magnetism, but the technology needed to stimulate the brain in a focused, controlled, and tolerable way was still missing.
1980: activating motor pathways
In the early 1980s, work by Merton and Morton showed that it was possible to activate motor pathways through electrical stimulation applied to the skull. The demonstration was significant, although the procedure was uncomfortable and had practical limitations.
1985: the first modern device
Anthony Barker and his team at the University of Sheffield developed a device in 1985 capable of stimulating the motor cortex using a magnetic coil. By producing movements in the hand muscles, they demonstrated that brain activity could be influenced non-invasively.
The technique began as a research tool. It made it possible to study the relationship between brain regions and motor responses, as well as to explore the conduction of nerve pathways.
The 1990s: from exploration to treatment
Repeating pulses opened up a new stage. Repetitive transcranial magnetic stimulation (rTMS) could produce effects that extended beyond a single stimulus. Different research teams began to investigate its use in psychiatric disorders, especially in treatment-resistant depression.
The focus shifted toward prefrontal regions related to mood. The question was no longer just what function a given area serves, but also how to therapeutically modify the activity of a network.
2008 and 2018: clinical expansion
Regulatory authorization for certain uses in depression drove the adoption of rTMS into clinical practice. Years later, protocols for obsessive-compulsive disorder were added, and research into other conditions continued.
Imaging, neuronavigation, and accelerated protocols
Functional magnetic resonance imaging and other tools made it possible to observe brain networks with greater precision. Neuronavigation made it possible to locate individualized targets, while new stimulation patterns sought to shorten the total duration of treatment.
Against this backdrop, accelerated protocols such as the SAINT protocol emerged, concentrating multiple sessions into just a few days and using more personalized targeting criteria.
A history still unfolding
The evolution of rTMS shows how a physical principle first became a research tool and later a therapeutic modality. The path continues with new frequencies, better targeting systems, and studies aimed at understanding which protocol is best suited to each person.
“New Hope for Treatment-Resistant Depression Without Medication” traces this history and explains how these advances have shaped modern neuromodulation.
