|MadSci Network: NeuroScience|
Although many researchers and clinicians may site studies from the past, these studies of direct cortical stimulation are not the only ones extant. Cortical stimulation is routinely performed and documented by neurosurgeons mapping epileptic siezure focii. It is probably the case that Dr. Schwartz was quoting Penfield's work in this area as an early and extremely well documented treatise on cortical stimulation.
On your related note: Trans-cranial, magnetic stimulation can be used to elicit motor responces in awake human subjects, non-invasively. These devices use precisely aligned magnetic fields to induce current in living neural tissue (like magnetic currents will do in wire). These devices are quite safe, but may elicit siezure like states in certain subjects. For a more complete treatment of this topic, please see A. Pascual-Leone's work in the journal: New Horizons in Neuropsychology (1994).
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