Screenshot image from Brainsight stereotactic image guidance software used to localize motor hotspot. A 3-dimensional reconstruction (A, bottom image) of a single T1 magnetic resonance scan of the brain (B) with positioning of the transcranial magnetic stimulation coil. An infrared optical sensor co-registers the position and orientation of the TMS coil relative to small refractory markers on the subject's cranium (A, top image). This provides the investigator with real-time information regarding the brain locus that will receive TMS given a position and orientation of the TMS coil, in order to minimize spatial variability in TMS application. (Image courtesy of Roch M. Comeau, Brainsight, Rogue Industries, Canada.).