TRANSCUTANEOUS MAGNETIC STIMULATION OF DESCENDING TRACTS IN THE CERVICAL SPINAL-CORD IN HUMANS

Percutaneous magnetic stimulation in humans allows non-invasive stimul ation of deeply situated nervous structures with little, if any, disco mfort and has proven its utility for brain stimulation. At the level o f the vertebral canal, magnetic stimulation readily elicits muscle res ponses through activation of the motor spinal roots, but there has bee n no evidence for direct stimulation of the spinal cord itself. The pr esent results document the feasibility of directly stimulating descend ing systems of the cervical spinal cord which synaptically activate mo toneurones. A working hypothesis is that the structure thus stimulated may be cortico-motoneuronal pyramidal axons or the propriospinal syst em.