"This well-written and very accessible text provides a well-grounded exposition of TMS and its value as a tool to study cognitive processes. Walsh and Pascual-Leone not only provide insights into the technique and its physical foundation, they also set their discussion in historical context. Cognitive neuroscientists will find great value in reading this text for its tutorial contributions."
-- John Jonides, University of Michigan

The mainstays of brain imaging techniques have been positron emission tomography (PET), functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and event-related potentials (ERPs). These methods all record direct or indirect measures of brain activity and correlate the activity patterns with behavior. But to go beyond the correlations established by these techniques and prove the necessity of an area for a given function, cognitive neuroscientists need to be able to reverse engineer the brain - i.e., to selectively remove components from information processing and assess their impact on the output.