Restorative Neurology and Neuroscience - Volume 36, issue 1

Authors: Platz, Thomas | Adler-Wiebe, Marija | Roschka, Sybille | Lotze, Martin

Article Type: Research Article

Abstract: Background: Motor rehabilitation after brain damage relies on motor re-learning as induced by specific training. Non-invasive brain stimulation (NIBS) can alter cortical excitability and thereby has a potential to enhance subsequent training-induced learning. Knowledge about any priming effects of NIBS on motor learning in healthy subjects can help to design targeted therapeutic applications in brain-damaged subjects. Objective: To examine whether complex motor learning in healthy subjects can be enhanced by intermittent theta burst stimulation (iTBS) to primary motor or sensory cortical areas. Methods: Eighteen young healthy subjects trained eight different arm motor tasks (arm ability training, …AAT) once a day for 5 days using their left non-dominant arm. Except for day 1 (baseline), training was performed after applying an excitatory form of repetitive transcranial magnetic stimulation (iTBS) to either (I) right M1 or (II) S1, or (III) sham stimulation to the right M1. Subjects were randomly assigned to conditions I, II, or III. Results: A principal component analysis of the motor behaviour data suggested eight independent motor abilities corresponding to the 8 trained tasks. AAT induced substantial motor learning across abilities with generalisation to a non-trained test of finger dexterity (Nine-Hole-Peg-Test, NHPT). Participants receiving iTBS (to either M1 or S1) showed better performance with the AAT tasks over the period of training compared to sham stimulation as well as a bigger improvement with the generalisation task (NHPT) for the trained left hand after training completion. Conclusion: Priming with an excitatory repetitive transcranial magnetic stimulation as iTBS of either M1 or S1 can enhance motor learning across different sensorimotor abilities. Show more

Keywords: Motor practice, learning, cortex, plasticity, transcranial magnetic stimulation

DOI: 10.3233/RNN-170774

Citation: Restorative Neurology and Neuroscience, vol. 36, no. 1, pp. 117-130, 2018

Authors: Kesar, Trisha M. | Eicholtz, Steven | Lin, Bethany J. | Wolf, Steven L. | Borich, Michael R.

Article Type: Research Article

Abstract: Background: The use of transcranial magnetic stimulation (TMS) to evaluate corticomotor excitability of lower limb (LL) muscles can provide insights about neuroplasticity mechanisms underlying LL rehabilitation. However, to date, a majority of TMS studies have focused on upper limb muscles. Posture-related activation is an important under-investigated factor influencing corticomotor excitability of LL muscles. Objective: The purpose of this study was to evaluate effects of posture and background activation on corticomotor excitability of ankle muscles. Methods: Fourteen young neurologically-unimpaired participants (26.1±4.1 years) completed the study. TMS-evoked motor evoked potentials (MEPs) were recorded from the tibialis anterior (TA) …and soleus during 4 conditions – standing, standing coactivation, sitting, and sitting coactivation. TA and soleus MEP amplitudes were compared during: (1) standing versus sitting;(2) standing coactivation (standing while activating both TA and soleus) versus sitting coactivation; and (3) standing coactivation versus standing. For each comparison, background EMG for TA and soleus were matched. Trial-to-trial coefficient of variation of MEP amplitude and coil-positioning errors were additional dependent variables. Results: No differences were observed in TA or soleus MEP amplitudes during standing versus sitting. Compared to sitting coactivation, larger MEPs were observed during standing coactivation for soleus but not TA. Compared to standing, the standing coactivation task demonstrated larger MEPs and reduced trial-to-trial MEP variability. Conclusion: Our findings suggest that incorporation of measurements in standing in future TMS studies may provide novel insights into neural circuits controlling LL muscles. Standing and standing coactivation tasks may be beneficial for obtaining functionally-relevant neuroplasticity assessments of LL musculature. Show more

Keywords: Activation, coactivation, lower limb, motor evoked potentials, neuroplasticity, posture

DOI: 10.3233/RNN-170773

Citation: Restorative Neurology and Neuroscience, vol. 36, no. 1, pp. 131-146, 2018