Takuya Sasaki1, Satoshi Kodama1, Naohiko Togashi1, Yuichiro Shirota1, Yusuke Sugiyama1, Shin-Ichi Tokushige2, Satomi Inomata-Terada3, Yasuo Terao3, Yoshikazu Ugawa4, Masashi Hamada5. 1. Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. 2. Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Department of Neurology, Kyorin University School of Medicine, Tokyo, Japan. 3. Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Department of Cell Physiology, Kyorin University School of Medicine, Tokyo, Japan. 4. Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan; Fukushima Global Medical Science Center, Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan. 5. Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. Electronic address: mhamada-tky@umin.net.
Abstract
BACKGROUND: Responses to continuous theta burst stimulation (cTBS) applied to the human primary motor cortex are highly variable between individuals. However, little is known about how to improve the after-effects of cTBS by adjusting the protocol characteristics. OBJECTIVE: We examined whether current directions adopted in the measurement of cortical motor excitability indexed as motor evoked potentials (MEPs) affect the responses to cTBS. We also tested whether the stimulus intensity of cTBS influences the after-effects. METHODS: Thirty-one healthy volunteers participated. The after-effects of cTBS with the conventional intensity of 80% of individual active motor threshold (AMT) (cTBS80%) were tested by measuring MEP amplitudes induced by not only posterior-anterior (PA) but also anterior-posterior (AP) and biphasic (PA-AP) currents. We also investigated cTBS with 65% AMT (cTBS65%) and 100% AMT (cTBS100%) in subjects who showed depression of MEP amplitudes after cTBS80%, as well as cTBS65% in subjects in whom facilitation of MEPs was induced by cTBS80%. RESULTS: Current directions in MEP measurement had no influence on the cTBS responses. In subjects whose MEPs were depressed by cTBS80%, cTBS100% partly induced MEP facilitation, while cTBS65% abolished the after-effects. In subjects who showed MEP facilitation by cTBS80%, cTBS65% partly induced MEP depression. CONCLUSIONS: Stimulus intensity of cTBS influenced the responses to cTBS, and lowering stimulus intensity induced the expected after-effects of cTBS in some subjects.
BACKGROUND: Responses to continuous theta burst stimulation (cTBS) applied to the human primary motor cortex are highly variable between individuals. However, little is known about how to improve the after-effects of cTBS by adjusting the protocol characteristics. OBJECTIVE: We examined whether current directions adopted in the measurement of cortical motor excitability indexed as motor evoked potentials (MEPs) affect the responses to cTBS. We also tested whether the stimulus intensity of cTBS influences the after-effects. METHODS: Thirty-one healthy volunteers participated. The after-effects of cTBS with the conventional intensity of 80% of individual active motor threshold (AMT) (cTBS80%) were tested by measuring MEP amplitudes induced by not only posterior-anterior (PA) but also anterior-posterior (AP) and biphasic (PA-AP) currents. We also investigated cTBS with 65% AMT (cTBS65%) and 100% AMT (cTBS100%) in subjects who showed depression of MEP amplitudes after cTBS80%, as well as cTBS65% in subjects in whom facilitation of MEPs was induced by cTBS80%. RESULTS: Current directions in MEP measurement had no influence on the cTBS responses. In subjects whose MEPs were depressed by cTBS80%, cTBS100% partly induced MEP facilitation, while cTBS65% abolished the after-effects. In subjects who showed MEP facilitation by cTBS80%, cTBS65% partly induced MEP depression. CONCLUSIONS: Stimulus intensity of cTBS influenced the responses to cTBS, and lowering stimulus intensity induced the expected after-effects of cTBS in some subjects.
Authors: Daniel M McCalley; Daniel H Lench; Jade D Doolittle; Julia P Imperatore; Michaela Hoffman; Colleen A Hanlon Journal: Sci Rep Date: 2021-04-22 Impact factor: 4.996
Authors: Denise Y Harvey; Laura DeLoretta; Priyanka P Shah-Basak; Rachel Wurzman; Daniela Sacchetti; Ahmed Ahmed; Abdou Thiam; Falk W Lohoff; Olufunsho Faseyitan; Roy H Hamilton Journal: Front Hum Neurosci Date: 2021-06-18 Impact factor: 3.169