Transcranial magnetic stimulation (TMS) is a FDA approved noninvasive method to cause depolarization or hyperpolarisation in the neurons of the brain. TMS uses electromagnetic induction to induce weak electric currents using a rapidly changing magnetic field; this can cause activity in specific or general parts of the brain with little discomfort, allowing for study of the brain's functioning and interconnections.

According to the United States National Institute of Mental Health, TMS "uses a magnet instead of an electrical current to activate the brain. An electromagnetic coil is held against the forehead and short electromagnetic pulses are administered through the coil. The magnetic pulse easily passes through the skull, and causes small electrical currents that stimulate nerve cells in the targeted brain region. And because this type of pulse generally does not reach further than two inches into the brain, scientists can select which parts of the brain will be affected and which will not be.

The magnetic field is about the same strength as that of a magnetic resonance imaging (MRI) scan. TMS uses rapidly changing magnetic field to stimulate the neurons in the brain. It uses highly focused MRI strength magnetic pulses to activate a specific region of the brain that regulates mood. It is indicated for the treatment of neuropsychiatric disorders and rehabilitation purposes.