title: A novel protocol to investigate motor training-induced plasticity and sensorimotor integration in the cerebellum and motor cortex.
abstract: Our group set out to develop a sensitive technique, capable of detecting output changes from the posterior fossa following a motor acquisition task. Transcranial magnetic stimulation (TMS) was applied over the right cerebellar cortex 5 ms in advance of test stimuli over the left cerebral motor cortex (M1), suppressing test motor-evoked potentials (MEPs) recorded in a distal hand muscle. Ten participants typed the letters Z, D, F, and P in randomized 8-letter sequences for ∼15 min, and 10 participants took part in the control condition. Cerebellar-M1 recruitment curves were established before and after the motor acquisition task. Cerebellar inhibition at 50% (CBI50) was defined as the intensity of cerebellar-M1 stimulations that produced MEPs that were 50% of the initial test MEP. Collection also occurred at stimulator intensities 5 and 10% above CBI50. A significant interaction effect of group (experimental and control) vs. time (pre- and postintervention) was observed [F(1,18) = 4.617, P = 0.046]. Post hoc tests showed a significant effect for the learning task in the experimental group [F(1,9) = 10.28, P = 0.01]. Further analysis showed specific disinhibition at CBI50 (P = 0.04), CBI50+5% (P = 0.008), and CBI50+10% (P = 0.01) for the experimental group only. Reaction time (P < 0.001) and accuracy (P = 0.006) improved significantly following practice, implying that disinhibition coincides with motor learning. No changes, however, were seen in the control condition. We conclude that this protocol is a sensitive technique that may be used to study cerebellar disinhibition with motor acquisition in vivo.
authors.affiliation: Faculty of Health Sciences, University of Ontario Institute of Technology, Oshawa, Ontario, Canada; and.
authors.forename: Julianne
authors.initials: J
authors.lastname: Baarbé
authors.forename: Paul
authors.initials: P
authors.lastname: Yielder
authors.forename: Julian
authors.initials: J
authors.lastname: Daligadu
authors.forename: Hushyar
authors.initials: H
authors.lastname: Behbahani
authors.forename: Heidi
authors.initials: H
authors.lastname: Haavik
authors.forename: Bernadette
authors.initials: B
authors.lastname: Murphy
mesh_terms: D000328:Adult; D002531:Cerebellum / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D019054:Evoked Potentials, Motor; D005260:Female; D006225:Hand / Q000294:innervation / Q000502:physiology; D006801:Humans; D007858:Learning; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity; D011597:Psychomotor Performance; D012677:Sensation; D050781:Transcranial Magnetic Stimulation
keywords: cerebellum; motor acquisition task; noninvasive cerebellar stimulation; plasticity; sensorimotor integration; transcranial magnetic stimulation