The NIH/NIGMS
Center for Integrative Biomedical Computing

There has been a recent explosion of interest in the use of noninvasive transcranial brain stimulation (or "neurostimulation"), both in clinical settings and as a research tool. One of the two main ways to stimulate the brain transcranially is to run a current to the brain through the magnetic fields generated by a coil that is held near the scalp. This approach has been approved by the FDA for treating depression. The other main approach uses electrodes placed on the scalp to "inject" current into the head, or apply voltage on the scalp, which is known as transcranial direct current stimulation (tDCS) or transcranial alternating current stimulation (tACS), depending on the type of current or voltage source used. Various neurostimulation technologies have been tested in human experiments for a huge variety of applications including motor rehabilitation, speech therapy, enhancement of cognitive learning, and treating depression and other affective and behavioral disorders, chronic pain syndrome, post-traumatic stress disorder, and others.

TMS
Transcranial Magnetic Stimulation (TMS) of the human motor cortex.