TMS involves temporarily applying a pulsating magnetic field to a particular area of the brain in order to interfere with brain functioning of that particular area. Using this method, researchers can test which behaviors may be linked to different areas of the brain by examining behavioral changes during disruption to the brain area in question. TMS is a useful tool for studying cognition because it is temporary, relatively non-invasive, and can be used with awake subjects.
Pobric, G., Jefferies, E., & Ralph, M. A. L. (2010). Category-specific versus category-general semantic impairment induced by transcranial magnetic stimulation. Current Biology, 20(10), 964-968.
Washburn, D. A., Gulledge, J. P., Beran, M. J., & Smith, J. D. (2010). With his memory magnetically erased, a monkey knows he is uncertain. Biology Letters, 6(2), 160-162.