Details

Autor(en) / Beteiligte

• Proessl, F.
• Canino, M. C.
• Beckner, M. E.
• Sinnott, A. M.
• Eagle, S. R.
• LaGoy, A. D.
• Conkright, W. R.
• Sterczala, A. J.
• Connaboy, C.
• Ferrarelli, F.
• Germain, A.
• Nindl, B. C.
• Flanagan, S. D.

Titel

Characterizing off-target corticospinal responses to double-cone transcranial magnetic stimulation

Ist Teil von

• Experimental brain research, 2021-04, Vol.239 (4), p.1099-1110

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2021

Quelle

SpringerLink

Beschreibungen/Notizen

• Introduction The double-cone coil (D-CONE) is frequently used in transcranial magnetic stimulation (TMS) experiments that target the motor cortex (M1) lower-limb representation. Anecdotal evidence and modeling studies have shed light on the off-target effects of D-CONE TMS but the physiological extent remains undetermined. Purpose To characterize the off-target effects of D-CONE TMS based on bilateral corticospinal responses in the legs and hands. Methods Thirty ( N  = 30) participants (9 women, age: 26 ± 5yrs) completed a stimulus–response curve procedure with D-CONE TMS applied to the dominant vastus lateralis (cVL) and motor-evoked potentials (MEPs) recorded in each active VL and resting first dorsal interosseous (FDI). As a positive control (CON), the dominant FDI was directly targeted with a figure-of-eight coil and MEPs were similarly recorded in each active FDI and resting VL. MEP MAX , V50 and MEP latencies were compared with repeated-measures ANOVAs or mixed-effects analysis and Bonferroni-corrected pairwise comparisons. Results Off-target responses were evident in all muscles, with similar MEP MAX in the target (cVL) and off-target (iVL) leg ( p  = 0.99 ) and cFDI compared with CON ( p  = 0.99 ). cFDI and CON MEP MAX were greater than iFDI ( p  < 0.01). A main effect of target ( p  < 0.001) indicated that latencies were shorter with CON but similar in all muscles with D-CONE. Discussion Concurrent MEP recordings in bilateral upper- and lower-extremity muscles confirm that lower-limb D-CONE TMS produces substantial distance-dependent off-target effects. In addition to monitoring corticospinal responses in off-target muscles to improve targeting accuracy in real-time, future studies may incorporate off-target information into statistical models post-hoc.