TMS History
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TMS History

A Background and History of Transcranial Magnetic Stimulation (TMS)

Transcranial magnetic stimulation (TMS) is a painless, non-invasive therapy designed for people who struggle with chronic, treatment-resistant mental illnesses. Researchers have found that a significant proportion (10-30%) of people with depression do not experience improvement with antidepressant medications.1 Fortunately, scientists recently have discovered that TMS can effectively treat persistent depression where traditional drug therapies have failed. In fact, evidence suggests that up to 70.6% of people who complete a full TMS treatment will see improvement in their symptoms and to 41.2% will experience permanent remission,2 releasing them from the devastating burden of depression—without the unpleasant side effects of antidepressants.

Neurons transmit small electrical pulses signaling to release neurotransmitters

Scientists believe prefrontal cortex neuron malfunction causes imbalanced release of neurotransmitters

Before they could develop any effective treatment for depression, scientists first had to learn about the mechanisms that cause this mental illness. They discovered that brain cells (called neurons) in the prefrontal cortex work by transmitting small electrical pulses to one another, signaling them to release chemicals called neurotransmitters. The brain relies on many different neurotransmitters to perform various important functions, and a healthy balance of three neurotransmitters in particular—called serotonin, dopamine, and norepinephrine—is critical for maintaining emotional health and wellbeing. When prefrontal cortex neurons malfunction, they may fail to send the appropriate electrical signals that stimulate a balanced release of these important neurotransmitters. Scientists believe that the subsequent chemical imbalance of serotonin, dopamine, and norepinephrine is responsible for depression.

TMS works by helping these malfunctioning neurons release neurotransmitters into the brain. During a TMS treatment session for depression, a clinician positions a small magnetic coil near the top-front area of the patient’s head, directly above the prefrontal cortex. The coil releases small electromagnetic currents that simulate the body’s natural electric nerve impulses, signaling neurons to release the specific neurotransmitters involved in regulating depression. The technique is completely painless, and patients remain awake for the entire treatment session. Patients who undergo a full course of TMS typically receive 20 minutes of TMS per session, five times per week, for four to six weeks.3 For many patients, this short, non-invasive treatment safely and conveniently alleviates stubborn symptoms of depression where traditional medications have failed.

Alessandro Volta (1745-1827) on 10000 Lire 1984 Banknote from Italy. Italian physicist discovered electric activity in living organisms.

While the procedure may seem like futuristic science fiction, scientists and inventors began laying the foundations of TMS more than 200 years ago. In 1790, an Italian scientist named Alessandro Volta studied the effects of electricity on the body by attaching frog legs to a metal gate. When lightning struck the gate, Volta observed that the frog legs twitched, leading him to conclude that bodies contain some kind of electrical activity—long before the formal discovery of electrical nerve impulses.

In 1831, English scientist Michael Faraday significantly advanced our understanding of electromagnetism when he observed that electrical currents create magnetic fields and, vice versa, magnetic fields create electrical currents. When Faraday passed electric pulses though a metal coil, he found that the electrical current generated a magnetic field that could transmit a new electrical current into another coil nearby.4

Although Faraday did not directly test the effects of electromagnetism on the human brain, his experiments demonstrated that electricity and magnetism can be converted back and forth to intentionally alter the energy state of nearby objects. The legacy of Volta’s and Faraday’s discoveries would go on to inform the basic scientific principles that make TMS possible today.

By the late 1800s, innovators realized that the science of electricity and magnetism could play an important role in health care. Equipped with newfound knowledge that electrical impulses help to regulate brain functions, scientists set out to develop electricity-based treatments for disorders of the brain, both neurological and psychiatric. One of the earliest of these was electroconvulsive therapy (ECT), a procedure designed to treat schizophrenia and other psychiatric disorders, including treatment-resistant depression, by using direct electrical currents to intentionally trigger seizures in anesthetized patients.5

Statue of Michael Faraday in Savoy Place, London. Faraday discovered that electrical currents can be transmitted via magnetic fields.

ECT was a popular treatment for nearly 50 years after its invention in 1938, but the procedure remains controversial for its side effects, which include pain and permanent memory loss. The technique fell out of favor in the early 1980s when the development of antidepressant drugs offered a safer, more effective option for treating depression and other mental disorders.6

Despite the widespread success of these medications, many psychiatrists remained troubled that some of their patients still experienced persistent depression that did not respond to antidepressant drugs. Scientists continued to refine electricity-based therapies, hoping to alleviate these patients of the debilitating burden of treatment-resistant depression without exposing them to the risks associated with ECT.

Our Dr. Dalkilic with Anthony Barker, who first used TMS in 1985 for neurological and motor disorders.

The answer came in 1985, when Anthony Barker used Faraday’s principles of electromagnetism to develop TMS, which uses a magnetized coil to stimulate electrical brain activity. Barker initially designed the technique for use on the brain’s motor cortex (which regulates body movements), using TMS as a diagnostic tool for neurological and motor disorders.4 Realizing that TMS was safe and highly effective, scientists began to test the effects of TMS on the prefrontal cortex and discovered that the treatment had significant benefits for people with psychiatric disorders.4

Because the TMS device uses magnetic fields to alter the brain’s electrical signals, rather than the traditional ECT method of direct electrical stimulation, the new therapy offers a safer, non-invasive alternative for people seeking relief from treatment-resistant depression.

In 2008, after a series of clinical trials to determine the safety and effectiveness of TMS, the Food and Drug Administration (FDA) formally approved TMS as a treatment protocol for medication-resistant major depressive disorder.7 Follow-up trials determined that most patients who experienced depression remission after treatment with TMS sustained their remission for at least a year after treatment, and the few who experienced a relapse were able to achieve remission again with additional TMS sessions.8

Dr. Dalkilic administering a session with Brainsway’s state of the art TMS machine during Covid-19 Era.

Today, TMS remains a popular, effective option for treatment-resistant depression. More than 20 million TMS treatments have been performed since 2009, and the procedure is covered by most insurance plans.9  The immense success of TMS for treating depression has inspired scientists to study the treatment for other mental disorders (including TMS for obsessive compulsive disorder (OCD), which received FDA approval in 201810), leading the charge to develop cutting-edge technologies that support and serve the needs of people with persistent mental health conditions.


1 Al-Harbi KS. (2012). Treatment-resistant depression: Therapeutic trends, challenges, and future directions. Patient Preference and Adherence, 2012(6):369-388.

2 Berlim MT, Van den Eynde F, Tovar-Perdomo S, et al. (2015). Augmenting antidepressants with deep transcranial magnetic stimulation (dTMS) in treatment-resistant major depression. World Journal of Biological Psychiatry, 15(7):570-578.

3 How Does TMS Work. Butler Hospital. Care New England Health System. (2020). Retrieved from

4 Noohi S & Amirsalari S. (2016). History, studies, and specific uses of repetitive transcranial magnetic stimulation (rTMS) in treating epilepsy. Iranian Journal of Child Neurology, 10(1):1-8.

5 Wright BA. (1990). An historical review of electroconvulsive therapy. Jefferson Journal of Psychiatry, 8(2):68-74.

6 Millhouse TM & Porter JH. (2016). A brief history of the development of antidepressant drugs: From monoamines to glutamate. Experimental and Clinical Psychopharmacology, 23(1):1-21.

7 Horvath JC, Mathews J, Demitrack MA, & Pascual-Leone A. (2010). The NeuroStar TMS Device: Conducting the FDA-approved protocol for treatment of depression. Journal of Visualized Experiments, 45.

8 Dunner DL, Aaronson ST, Sackeim HA, et al. (2014). Journal of Clinical Psychiatry, 75(12):1394-1401.

9 Carpenter LL, Philip NS (2020), The Future Is Now? Rapid Advances by Brain Stimulation Innovation. The American Journal of Psychiatry.

10 Food and Drug Administration. (2018). FDA permits marketing of transcranial magnetic stimulation for treatment of obsessive compulsive disorder. Retrieved from