page_title: Neurostimulation
section_title: Transcranial magnetic stimulation
hierarchical_section_title: Neurostimulation / Non-invasive brain stimulation / Transcranial magnetic stimulation
caption_attribution_description: English: Transcranial electrical stimulation is a specific subgroup of non-invasive brain stimulation techniques, which is based on the application of low-intensity electrical current. While tDCS uses constant current intensity, tRNS and tACS use oscillating current. The vertical axis represents the current intensity in milliamp (mA), while the horizontal axis illustrates the time-course. Abbreviations: tDCS, transcranial direct current stimulation; tRNS, transcranial random noise stimulation; tACS, transcranial alternating current stimulation.
context_page_description: Neurostimulation is the purposeful modulation of the nervous system's activity using invasive or non-invasive means. Neurostimulation usually refers to the electromagnetic approaches to neuromodulation.
  Neurostimulation technology can improve the life quality of those who are severely paralyzed or suffering from profound losses to various sense organs, as well as for permanent reduction of severe, chronic pain which would otherwise require constant, high-dose opioid therapy. It serves as the key part of neural prosthetics for hearing aids, artificial vision, artificial limbs, and brain-machine interfaces. In the case of neural stimulation, mostly an electrical stimulation is utilized and charge-balanced biphasic constant current waveforms or capacitively coupled charge injection approaches are adopted. Alternatively, transcranial magnetic stimulation and transcranial electric stimulation have been proposed as non-invasive methods in which either a magnetic field or transcranially applied electric currents cause neurostimulation.
context_section_description: Compared to electrical stimulation that utilizes brief, high-voltage electric shock to activate neurons, which can potentially activate pain fibers, transcranial magnetic stimulation (TMS) was developed by Baker in 1985. TMS uses a magnetic wire above the scalp, which carries a sharp and high current pulse. A time variant magnetic field is induced perpendicular to the coil due to the applied pulse which consequently generates an electric field based on Maxwell's law. The electric field provides the necessary current for a non-invasive and much less painful stimulation. There are two TMS devices called single pulse TMS and repetitive pulse TMS (rTMS) while the latter has greater effect but potential to cause seizure. TMS can be used for therapy particularly in psychiatry, as a tool to measure central motor conduction and a research tool to study different aspects of human brain physiology such as motor function, vision, and language. The rTMS method has been used to treat epilepsy with rates of 8–25 Hz for 10 seconds. The other therapeutic uses of rTMS include parkinson diseases, dystonia and mood diseases. Also, TMS can be used to determine the contribution of cortical networks to specific cognitive functions by disrupting activity in the focal brain region. Early, inconclusive, results have been obtained in recovery from coma (persistent vegetative state) by Pape et al. (2009).
caption: Transcranial electrical stimulation techniques. While tDCS uses constant current intensity, tRNS and tACS use oscillating current. The vertical axis represents the current intensity in milliamp (mA), while the horizontal axis illustrates the time-course.
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