The Laboratory for Magnetic Brain Stimulation at the Beth Israel Deaconess Medical Center and Harvard Medical School applies single-pulse, paired-pulse, and slow and fast repetitive transcranial magnetic stimulation (TMS) to the study of human cortical physiology in health and disease. We have both a clinical and a research component to the laboratory. In the clinical operation, we conduct motor central conduction time studies, intracortical excitability studies, non-invasive cortical mapping studies, and non-invasive studies for the determination of hemispheric language dominance. In the research operation, we have ongoing projects in the areas of neuroplasticity, neurorehabilitation and learning, and in the application of repetitive TMS to modulate cortical excitability in neuropsychiatric disorders. In addition, there is a strong devotion to teaching that involves medical students, residents and fellows, pregraduate and postgraduate students of the Neuroscience Program and the Massachussetts Institute of Technology, and any collegue interested in learning hands-on about TMS. In this context we organize the yearly Harvard Continuing Medical Education Course on transcranial magnetic stimulation.
Repetitive TMS (rTMS) seems to exert different effects on cortical excitability depending on the stimulation frequency and intensity. At a given intensity, "fast rTMS" at frequencies of 10 to 30 Hz, can enhance cortical excitability. On the other hand, "slow rTMS" at 1 Hz, can be shown to decrease cortical excitability. These modulatory effects of rTMS on cortical excitability can outlast the duration of the stimulation itself and might thus be used to normalized cortical excitability in various neuropsychiatric conditions. Marked inter-subject differences in the effects of different rTMS parameters on cortical excitability make it essential to individualize the stimulation parameters for a given desired effect. In our laboratory, the effects of repetitive TMS are being studied in depression, schizophrenia, slowness of motion in Parkinson's disease, post-stroke rehabilitation, phantom and other chonic pain syndromes, dystonia, cortical myoclonus, and focal epilepsy.
A stereotactic TMS system allowing precise anatomic correlation of the TMS findings has been developed on the basis of the projection of the TMS stimulation sites onto the subject's 3-D reconstructed brain MRI. Multimodal studies combining TMS with other neurophysiologic (evoked potentials, quantitative EEG) and neuroimaging techniques (functional MRI, SPECT) are employed in order to improve our understanding about the mechanisms of action of TMS and rTMS. Finally, collaboration with other laboratories allow us to conduct comparative studies in humans and animal models.
Our laboratory stays in close collaboration with Dr. Pascual-Leone's previous affiliation at the Unidad de Neurobiologia, Departamento de Fisiologia and the Unidad Docente de Neurologia, Departamento de Medicina, of the University of Valencia, and the Instituto Cajal, Consejo Superior de Investigaciones Cientificas in Spain. The work in Spain is continued under the direction of Prof. Dr. Maria Dolores Catala (Physiology) and Prof. Alvaro Pascual-Leone Pascual (Neurology), and involves Drs. Carlos Cañete, Francisco Tarazona, and Jose Maria Tormos.