Direct and indirect activation of human corticospinal neurons by transcranial magnetic and electrical stimulation

• Published in: Neuroscience letters Vol. 210; no. 1; pp. 45 - 48
• Main Authors: Nakamura, Hiroshi, Kitagawa, Hideki, Kawaguchi, Yoshiharu, Tsuji, Haruo
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 24.05.1996; Elsevier
• Subjects: Aged; Biological and medical sciences; Coil orientation; D and I hypothesis; D wave; Electric Stimulation; Female; Fundamental and applied biological sciences. Psychology; Humans; I wave; Magnetics; Male; Middle Aged; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Neurons - physiology; Pyramidal Tracts - cytology; Transcranial electrical stimulation; Transcranial magnetic stimulation; Vertebrates: nervous system and sense organs; D wave; Coil orientation; Transcranial magnetic stimulation; D and I hypothesis; I wave; Transcranial electrical stimulation; Human; Pyramidal motor pathway; Motor cortex; Electrical stimulus; Central nervous system; Magnetic stimulus; Electrophysiology; Excitability; Corticospinal bundle; Electromyography; Brain (vertebrata)
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/0304-3940(96)12659-8

Corticospinal volleys and surface electromyographic (EMG) responses evoked by magnetic and electrical transcranial stimulation were recorded simultaneously in three conscious human subjects. For magnetic stimulation, the figure-of-eight coil was held on the hand motor area either with the induced current through the brain flowing in a postero-anterior direction (P-A stimulation) or in a latero-medial direction (L-M stimulation). For electrical stimulation, the anode was placed 7 cm lateral to the vertex and cathode at the vertex (anodal stimulation). The P-A stimulation that was generally used preferentially evoked I waves, whereas the L-M and anodal stimulation preferentially evoked D wave. The results suggested that the mode of activation by transcranial magnetic stimulation altered, depending on its current direction, and the difference between P-M magnetic and electrical stimulation can be explained by the context of the D and I hypothesis.