Transcranial magnetic stimulation of the cerebral cortex

Surgical resection of the epileptic focus is an effective treatment for otherwise uncontrollable epileptic seizures. Localization of cerebral function in the region of the epileptic focus is a mandatory part of the presurgical evaluation. Development of magnetic stimulation for evaluation of speech and memory is technically feasible and will lead to safer, more efficient, noninvasive evaluation of seizure surgery patients. Strategies for predicting an optimum excitation circuit and field configurations are discussed. The goal is to maximize the rate of change of the magnetic field for a minimum of 20 mu s while not exceeding reasonable power requirements. The induced field level must be repeated at 15-20 Hz to maintain constant brain stimulation during the period of the test.<<ETX>>