MODEL RELEASED. Brain mapping. Woman undergoing image-guided transcranial magnetic stimulation (TMS) brain mapping. The electro-magnetic figure- of-eight coil (in researcher's hand) induces an electric current in a discrete area of the subject's brain. The area targeted is mapped to a scan of her brain held on computer (right), via trackers on the glasses (right) and the coil. The subject experiences different physiological reactions depending upon where the electrical current is aimed. For example, when placed over the visual processing area, colour discrimination or the detection of visual stimuli may be impaired. The information is used to build a map of the functions of areas of the brain.