Transcranial magnetic stimulation (TMS)

Transcranial magnetic stimulation (TMS) is a method to excite neurons in the brain from the outside of the scalp. TMS uses weak electric currents that are induced in the tissue by rapidly changing magnetic fields, known as electromagnetic induction. The induced TMS pulse thus interferes with neuronal signalling, causing a temporary neuronal inhibition. TMS allows for localization of cognitive, motor and sensory functions and has an important role in validating e.g. functional imaging methods, like fMRI. TMS has been used as treatment for depression and for auditory hallucinations in schizophrenia. Modern TMS laboratories use MRI-guided neuronavigation techniques to identify anatomical landmarks where to apply the electromagnetic induction coil on the scalp.

The figure shows the application of the TMS induction coil over the motor cortex. From Bergen fMRI Group.