Authors: Borich, Michael R. | Kimberley, Teresa Jacobson
Article Type: Research Article
Abstract: Purpose: Sleep following training can enhance motor skill memory consolidation while chronic sleep disruption can have the converse effect. The aim of this investigation was to explore the relationship between sleep measured by wrist actigraphy, motor skill consolidation and primary motor cortex excitability in young, healthy individuals. Methods: Training was a visuospatial finger-tracking task. Dependent measures included tracking skill performance, cortical excitability, measures of sleep, and level of arousal. Assessments occurred pre-training, post-training and at 12 h and 24 h retention. An activity monitor was worn on the wrist during the nights preceding and following training. Results: Results indicate that …sleep during the night following training was predictive of 1) offline skill consolidation following training (R2 = 0.34) and 2) cortical excitability at 24 h follow-up (R2 = 0.35) with less time spent awake associated with better skill performance and lower cortical excitability at 24 h follow-up. No difference in measures of sleep was observed between nights of sleep (p > 0.05). Sleep the night before training did not influence skill performance, skill acquisition during training, nor measures of cortical excitability at pre-training assessment. Conclusions: These findings suggest a relationship between motor skill development, cortical excitability and sleep following training. These results invite further investigation into the utility of actigraphy as a low-cost, easy-to-administer alternative to polysomnography for short and long-term evaluation of the relationship between sleep, cortical excitability and motor skill learning in healthy and patient populations. Show more
Keywords: Actigraphy, sleep, motor learning, cortical excitability, TMS, memory, consolidation, enhancement
DOI: 10.3233/RNN-2011-0622
Citation: Restorative Neurology and Neuroscience, vol. 30, no. 2, pp. 81-90, 2012
Authors: Borich, Michael R. | Neva, Jason L. | Boyd, Lara A.
Article Type: Research Article
Abstract: Purpose: Rehabilitation interventions need to be optimized to maximize therapeutic effects and minimize stroke-related disability. However, a comprehensive understanding of the neural substrates underlying recovery is lacking. The purpose of this study was to investigate relationships between brain anatomy, physiology and hand motor function in individuals with chronic stroke. Methods: Transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) approaches were used to evaluate cortical excitability and brain structural morphometry in individuals with chronic stroke. Hemispheric differences and relationships between these measures and hand dexterity were evaluated. Results: Hemispheric differences were observed for TMS and MRI measures. Bilateral hand dexterity …correlated with TMS resting motor threshold and precentral gyral thickness. Transcallosal inhibition across hemispheres was positively associated with midcallosal white matter volume. Regression modeling results demonstrated that combining TMS and MRI measures predicted unique amounts of variance in hand dexterity. Conclusions: Results confirm and extend findings showing differences in brain structure and function after stroke. Results suggested a structure-function relationship underlying interhemispheric connectivity in chronic stroke. The utility of combined TMS and MRI measures to predict motor function can be used in future investigations to aid identifying optimal biomarkers of stroke recovery to predict response to rehabilitation to maximize treatment outcomes. Show more
Keywords: Stroke, transcranial magnetic stimulation, magnetic resonance imaging, cortical excitability, morphometry, rehabilitation, hand dexterity
DOI: 10.3233/RNN-140425
Citation: Restorative Neurology and Neuroscience, vol. 33, no. 1, pp. 31-42, 2015
Authors: Palmer, Jacqueline A. | Wolf, Steven L. | Borich, Michael R.
Article Type: Research Article
Abstract: Background: Paired associative stimulation (PAS) combining repeated pairing of electrical stimulation of a peripheral nerve with transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) can induce neuroplastic adaptations in the human brain and enhance motor learning in neurologically-intact individuals. However, the extent to which PAS is an effective technique for inducing associative plasticity and improving motor function in individuals post-stroke is unclear. Objective: The objective of this pilot study was to investigate the effects of a single session of PAS to modulate corticomotor excitability and motor skill performance in individuals post-stroke. Methods: Seven individuals with chronic stroke completed …two separate visits separated by at least one week. We assessed general corticomotor excitability, intracortical network activity and behavioral outcomes prior to and at three time points following PAS and compared these outcomes to those following a sham PAS condition (PASSHAM ). Results: Following PAS, we found increased general corticomotor excitability but no significant difference in behavioral measures between PAS conditions. There was a relationship between PAS-induced corticomotor excitability increase and enhanced motor skill performance across post-PAS testing time points. Conclusion: These results provide preliminary evidence for the potential of PAS to increase corticomotor excitability that could favorably impact motor skill performance in chronic individuals post-stroke and are an important first step for future studies investigating the clinical application and behavioral relevance of PAS interventions in post stroke patient populations. Show more
Keywords: Transcranial magnetic stimulation, paired associative stimulation, motor learning
DOI: 10.3233/RNN-170785
Citation: Restorative Neurology and Neuroscience, vol. 36, no. 2, pp. 183-194, 2018
Authors: Kimberley, Teresa Jacobson | Borich, Michael R. | Arora, Sanjeev | Siebner, Hartwig R.
Article Type: Research Article
Abstract: Purpose: The ability of low-frequency repetitive transcranial magnetic stimulation (rTMS) to enhance intracortical inhibition has motivated its use as a potential therapeutic intervention in focal hand dystonia (FHD). In this preliminary investigation, we assessed the physiologic and behavioral effects of multiple sessions of rTMS in FHD. Methods: 12 patients with FHD underwent five daily-sessions of 1 Hz rTMS to contralateral dorsal premotor cortex (dPMC). Patients held a pencil and made movements that did not elicit dystonic symptoms during rTMS. We hypothesized that an active but non-dystonic motor state would increase beneficial effects of rTMS. Five additional patients received sham-rTMS protocol. …The area under curve (AUC) of the motor evoked potentials and the cortical silent period (CSP) were measured to assess changes in corticospinal excitability and intracortical inhibition, respectively. Behavioral measures included pen force and velocity during handwriting and subjective report. Results: Multiple-session rTMS strengthened intracortical inhibition causing a prolongation of CSP after 3 days of intervention and pen force was reduced at day 1 and 5, leaving other measures unchanged. 68% of patients self-reported as ‘responders’ at day 5, and 58% at follow-up. Age predicted responders. Conclusions: A strong therapeutic potential of this rTMS paradigm in FHD was not supported but findings warrant further investigation. Show more
Keywords: Focal hand dystonia, rehabilitation, rTMS, writer's cramp, clinical
DOI: 10.3233/RNN-120259
Citation: Restorative Neurology and Neuroscience, vol. 31, no. 5, pp. 533-542, 2013
Authors: Jones, Paul W. | Borich, Michael R. | Vavsour, Irene | Mackay, Alex | Boyd, Lara A.
Article Type: Research Article
Abstract: Background: Hemiparesis is one of the most prevalent chronic disabilities after stroke. Biochemical and structural magnetic resonance imaging approaches may be employed to study the neural substrates underpinning upper-extremity (UE) recovery after chronic stroke. Objective: The purposes of this study were to 1) quantify anatomical and metabolic differences in the precentral gyrus, and 2) test the relationships between anatomical and metabolic differences, and hemiparetic arm function in individuals in the chronic stage of stroke recovery. Our hypotheses were: 1) the Stroke group would exhibit reduced precentral gyrus cortical thickness and lower concentrations of total N-acetylaspartate (tNAA) and glutamate+glutamine (Glx) in …the ipsilesional motor cortex; and 2) that each of these measures would be associated with UE motor function after stroke. Methods: Seventeen individuals with chronic (>6 months) subcortical ischemic stroke and eleven neurologically healthy controls were recruited. Single voxel proton magnetic resonance spectroscopy (H1 MRS) was performed to measure metabolite concentrations of tNAA and Glx in the precentral gyrus in both ipsilesional and contralesional hemispheres. Surface-based cortical morphometry was used to quantify precentral gyral thickness. Upper-extremity motor function was assessed using the Wolf Motor Function Test (WMFT). Results: Results demonstrated significantly lower ipsilesional tNAA and Glx concentrations and precentral gyrus thickness in the Stroke group. Ipsilesional tNAA and Glx concentration and precentral gyrus thickness was significantly lower in the ipsilesional hemisphere in the Stroke group. Parametric correlation analyses revealed a significant positive relationship between precentral gyrus thickness and tNAA concentration bilaterally. Multivariate regression analyses revealed that ipsilesional concentrations of tNAA and Glx predicted the largest amount of variance in WMFT scores. Cortical thickness measures alone did not predict a significant amount of variance in WMFT scores. Conclusion: While stroke impairs both structure and biochemistry in the ipsilesional hemisphere our data suggest that tNAA has the strongest relationship with motor function. Show more
Keywords: Stroke, human, metabolite, motor function, cortical thickness
DOI: 10.3233/RNN-150623
Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 733-746, 2016
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
Authors: Edwards, Jodi D. | Meehan, Sean K. | Linsdell, Meghan A. | Borich, Michael R. | Anbarani, Keivan | Jones, Paul W. | Ferris, Jennifer | Boyd, Lara A.
Article Type: Research Article
Abstract: Purpose: The purpose of the present study was to assess changes in thresholds for the onset of short intracortical inhibition (SICI) and intracortical facilitation (ICF) in individuals with chronic stroke compared to age-matched healthy adults and evaluate the relationship between these thresholds and motor function in the chronic stroke group. Methods: Paired-pulse transcranial magnetic stimulation was used to derive thresholds for the onset of SICI and ICF in 12 neurologically healthy and 12 individuals with chronic stroke. Motor evoked potentials were elicited by a test stimulus of fixed intensity preceded by a conditioning stimulus ranging from 0%–125% of active motor …threshold to generate recruitment curves. Regression functions were fit to these recruitment curves to identify thresholds for the onset of SICI and ICF. Mixed measures analysis of variance was used to compare thresholds for each hemisphere within and between groups. Results: Results showed a significant three-way interaction between Group (stroke, healthy), Hemisphere (ipsilesional, contralesional) and Stimulus interval (2 ms, 12 ms). Significant differences in the thresholds for the onset of both SICI and ICF were present in individuals with chronic stroke, with no between hemisphere differences for the control group. When compared to age-matched controls, comparisons revealed significant reductions in ipsilesional, but not contralesional thresholds for the onset of ICF, and significant reductions in contralesional, but not ipsilesional, thresholds for the onset of SICI in individuals with chronic stroke. In addition, as thresholds for ICF and SICI in stroke patients approached the level of healthy adults, higher function on the Wolf Motor Function Test was observed. Conclusions: Reduced thresholds for the onset of SICI and ICF observed in the present study indicate that both inhibitory and facilitatory systems mediate changes in cortical excitability in chronic stroke patients. The association between higher onset thresholds and motor function in the stroke group also suggests that these thresholds have potential utility for tracking functional motor improvements in patients with chronic stroke. This study provides new insights to further characterize changes in intracortical neurotransmission that play an important role in modulating neuroplasticity and the potential relationship between inhibitory and facilitatory networks and motor function post-stroke. Show more
Keywords: Intracortical inhibition, intracortical facilitation, transcranial magnetic stimulation, chronic stroke
DOI: 10.3233/RNN-120300
Citation: Restorative Neurology and Neuroscience, vol. 31, no. 6, pp. 693-705, 2013
