TY  - JOUR
AU  - Volz, Lukas
AU  - Hamada, Masashi
AU  - Michely, Jochen
AU  - Pool, Eva‐Maria
AU  - Nettekoven, Charlotte
AU  - Rothwell, John C.
AU  - Grefkes‐Hermann, Christian
TI  - Modulation of I‐wave generating pathways by TBS: a model of plasticity induction
JO  - The journal of physiology
VL  - 597
IS  - 24
SN  - 1469-7793
CY  - Hoboken, NJ
PB  - Wiley-Blackwell
M1  - FZJ-2019-05286
SP  - 5963-5971
PY  - 2019
AB  - Plasticity‐induction following theta burst transcranial stimulation (TBS) varies considerably across subjects, and the underlying neurophysiological mechanisms remain poorly understood, representing a challenge for scientific and clinical applications. In human motor cortex (M1), recruitment of indirect waves (I‐waves) can be probed by the excess latency of motor‐evoked potentials elicited by transcranial magnetic stimulation with an anterior–posterior (AP) orientation over the latency of motor‐evoked potentials evoked by direct activation of corticospinal axons using lateromedial (LM) stimulation, referred to as the ‘AP‐LM latency’ difference. Importantly, AP‐LM latency has been shown to predict individual responses to TBS across subjects. We, therefore, hypothesized that the plastic changes in corticospinal excitability induced by TBS are the result, at least in part, of changes in excitability of these same I‐wave generating pathways. In 20 healthy subjects, we investigated whether intermittent TBS (iTBS) modulates I‐wave recruitment as reflected by changes in the AP‐LM latency. As expected, we found that AP‐LM latencies before iTBS were associated with iTBS‐induced excitability changes. A novel finding was that iTBS reduced AP‐LM latency, and that this reduction significantly correlated with changes in cortical excitability observed following iTBS: subjects with larger reductions in AP‐LM latencies featured larger increases in cortical excitability following iTBS. Our findings suggest that plasticity‐induction by iTBS may derive from the modulation of I‐wave generating pathways projecting onto M1, accounting for the predictive potential of I‐wave recruitment. The excitability of I‐wave generating pathways may serve a critical role in modulating motor cortical excitability and hence represent a promising target for novel repetitive transcranial magnetic stimulation protocols.
LB  - PUB:(DE-HGF)16
C6  - pmid:31647123
UR  - <Go to ISI:>//WOS:000495881100001
DO  - DOI:10.1113/JP278636
UR  - https://juser.fz-juelich.de/record/866040
ER  -