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1.
Front Hum Neurosci ; 18: 1358551, 2024.
Article in English | MEDLINE | ID: mdl-38628971

ABSTRACT

Objective, rapid evaluation of cognitive function is critical for identifying situational impairment due to sleep deprivation. The present study used brain vital sign monitoring to evaluate acute changes in cognitive function for healthy adults. Thirty (30) participants were scanned using portable electroencephalography before and after either a night of regular sleep or a night of total sleep deprivation. Brain vital signs were extracted from three established event-related potential components: (1) the N100 (Auditory sensation); (2) the P300 (Basic attention); and (3) the N400 (Cognitive processing) for all time points. As predicted, the P300 amplitude was significantly reduced in the sleep deprivation group. The findings indicate that it is possible to detect situational cognitive impairment due to sleep deprivation using objective, rapid brain vital sign monitoring.

2.
Neuroimage ; 263: 119644, 2022 11.
Article in English | MEDLINE | ID: mdl-36170952

ABSTRACT

White matter (WM) neuroplasticity in the human brain has been tracked non-invasively using advanced magnetic resonance imaging techniques, with increasing evidence for improved axonal transmission efficiency as a central mechanism. The current study is the culmination of a series of studies, which characterized the structure-function relationship of WM transmission efficiency in the cortico-spinal tract (CST) during motor learning. Here, we test the hypothesis that increased transmission efficiency is linked directly to increased myelination using myelin water imaging (MWI). MWI was used to evaluate neuroplasticity-related improvements in the CST. The MWI findings were then compared to diffusion tensor imaging (DTI) results, with the secondary hypothesis that radial diffusivity (RD) would have a stronger relationship than axial diffusivity (AD) if the changes were due to increased myelination. Both MWI and RD data showed the predicted pattern of significant results, strongly supporting that increased myelination plays a central role in WM neuroplasticity.


Subject(s)
White Matter , Humans , White Matter/diagnostic imaging , White Matter/pathology , Diffusion Tensor Imaging/methods , Brain/diagnostic imaging , Diffusion Magnetic Resonance Imaging , Magnetic Resonance Imaging , Water
3.
Neurorehabil Neural Repair ; 36(6): 381-389, 2022 06.
Article in English | MEDLINE | ID: mdl-35533214

ABSTRACT

BACKGROUND: Myelin asymmetry ratios (MARs) relate and contribute to motor impairment and function after stroke. Physical activity (PA) may induce myelin plasticity, potentially mitigating hemispheric myelin asymmetries that can occur after a stroke. OBJECTIVE: The aim of this study was to determine whether individuals with higher levels of PA showed lower MAR compared to individuals with lower levels of PA. METHODS: Myelin water fraction was obtained from 5 bilateral motor regions in 22 individuals with chronic stroke and 26 healthy older adults. Activity levels were quantified with wrist accelerometers worn for a period of 72 hours (3 days). Higher and lower PA levels were defined by a cluster analysis within each group. RESULTS: MAR was similar regardless of PA level within the older adult group. Compared to the higher PA stroke group, lower PA stroke participants displayed greater MAR. There was no difference in MAR between the stroke and older adult higher PA groups. Within the lower PA groups, individuals with stroke showed greater MAR compared to the older adults. Arm impairment, lesion volume, age, time since stroke, and preferential arm use were not different between the PA stroke groups, suggesting that motor impairment severity and extent of brain damage did not drive differences in PA. CONCLUSION: Individuals who have had a stroke and are also physically active display lower MAR (i.e., similar myelin in both hemispheres) in motor regions. High levels of PA may be neuroprotective and mitigate myelin asymmetries once a neurological insult, such as a stroke, occurs. Alternately, it is possible that promoting high levels of PA after a stroke may reduce myelin asymmetries.


Subject(s)
Myelin Sheath , Stroke , Aged , Exercise , Humans , Upper Extremity , Wrist
4.
Exp Neurol ; 346: 113853, 2021 12.
Article in English | MEDLINE | ID: mdl-34464653

ABSTRACT

Experience-dependent white matter plasticity offers new potential for rehabilitation-induced recovery after neurotrauma. This first-in-human translational experiment combined myelin water imaging in humans and genetic fate-mapping of oligodendrocyte lineage cells in mice to investigate whether downhill locomotor rehabilitation that emphasizes eccentric muscle actions promotes white matter plasticity and recovery in chronic, incomplete spinal cord injury (SCI). In humans, of 20 individuals with SCI that enrolled, four passed the imaging screen and had myelin water imaging before and after a 12-week (3 times/week) downhill locomotor treadmill training program (SCI + DH). One individual was excluded for imaging artifacts. Uninjured control participants (n = 7) had two myelin water imaging sessions within the same day. Changes in myelin water fraction (MWF), a histopathologically-validated myelin biomarker, were analyzed in a priori motor learning and non-motor learning brain regions and the cervical spinal cord using statistical approaches appropriate for small sample sizes. PDGFRα-CreERT2:mT/mG mice, that express green fluorescent protein on oligodendrocyte precursor cells and subsequent newly-differentiated oligodendrocytes upon tamoxifen-induced recombination, were either naive (n = 6) or received a moderate (75 kilodyne), contusive SCI at T9 and were randomized to downhill training (n = 6) or unexercised groups (n = 6). We initiated recombination 29 days post-injury, seven days prior to downhill training. Mice underwent two weeks of daily downhill training on the same 10% decline grade used in humans. Between-group comparison of functional (motor and sensory) and histological (oligodendrogenesis, oligodendroglial/axon interaction, paranodal structure) outcomes occurred post-training. In humans with SCI, downhill training increased MWF in brain motor learning regions (postcentral, precuneus) and mixed motor and sensory tracts of the ventral cervical spinal cord compared to control participants (P < 0.05). In mice with thoracic SCI, downhill training induced oligodendrogenesis in cervical dorsal and lateral white matter, increased axon-oligodendroglial interactions, and normalized paranodal structure in dorsal column sensory tracts (P < 0.05). Downhill training improved sensorimotor recovery in mice by normalizing hip and knee motor control and reducing hyperalgesia, both of which were associated with new oligodendrocytes in the cervical dorsal columns (P < 0.05). Our findings indicate that eccentric-focused, downhill rehabilitation promotes white matter plasticity and improved function in chronic SCI, likely via oligodendrogenesis in nervous system regions activated by the training paradigm. Together, these data reveal an exciting role for eccentric training in white matter plasticity and sensorimotor recovery after SCI.


Subject(s)
Neurological Rehabilitation/methods , Neuronal Plasticity/physiology , Psychomotor Performance/physiology , Recovery of Function/physiology , Spinal Cord Injuries/rehabilitation , White Matter/physiology , Adolescent , Adult , Aged , Aged, 80 and over , Animals , Chronic Disease , Exercise Test/methods , Female , Humans , Magnetic Resonance Imaging , Male , Mice , Mice, 129 Strain , Mice, Inbred C57BL , Mice, Transgenic , Middle Aged , Spinal Cord Injuries/diagnostic imaging , Spinal Cord Injuries/physiopathology , White Matter/diagnostic imaging , Young Adult
5.
Front Neurosci ; 15: 670563, 2021.
Article in English | MEDLINE | ID: mdl-34434084

ABSTRACT

Background: Prior concussion studies have shown that objective neurophysiological measures are sensitive to detecting concussive and subconcussive impairments in youth ice-hockey. These studies monitored brain vital signs at rink-side using a within-subjects design to demonstrate significant changes from pre-season baseline scans. However, practical clinical implementation must overcome inherent challenges related to any dependence on a baseline. This requires establishing the start of normative reference data sets. Methods: The current study collected specific reference data for N = 58 elite, youth, male ice-hockey players and compared these with a general reference dataset from N = 135 of males and females across the lifespan. The elite hockey players were recruited to a select training camp through CAA Hockey, a management agency for players drafted to leagues such as the National Hockey League (NHL). The statistical analysis included a test-retest comparison to establish reliability, and a multivariate analysis of covariance to evaluate differences in brain vital signs between groups with age as a covariate. Findings: Test-retest assessments for brain vital signs evoked potentials showed moderate-to-good reliability (Cronbach's Alpha > 0.7, Intraclass correlation coefficient > 0.5) in five out of six measures. The multivariate analysis of covariance showed no overall effect for group (p = 0.105), and a significant effect of age as a covariate was observed (p < 0.001). Adjusting for the effect of age, a significant difference was observed in the measure of N100 latency (p = 0.022) between elite hockey players and the heterogeneous control group. Interpretation: The findings support the concept that normative physiological data can be used in brain vital signs evaluation in athletes, and should additionally be stratified for age, skill level, and experience. These can be combined with general norms and/or individual baseline assessments where appropriate and/or possible. The current results allow for brain vital sign evaluation independent of baseline assessment, therefore enabling objective neurophysiological evaluation of concussion management and cognitive performance optimization in ice-hockey.

6.
Neurorehabil Neural Repair ; 35(6): 513-524, 2021 06.
Article in English | MEDLINE | ID: mdl-33825574

ABSTRACT

OBJECTIVE: Activity patterns across brain regions that can be characterized at rest (ie, resting-state functional connectivity [rsFC]) are disrupted after stroke and linked to impairments in motor function. While changes in rsFC are associated with motor recovery, it is not clear how rsFC is modulated by skilled motor practice used to promote recovery. The current study examined how rsFC is modulated by skilled motor practice after stroke and how changes in rsFC are linked to motor learning. METHODS: Two groups of participants (individuals with stroke and age-matched controls) engaged in 4 weeks of skilled motor practice of a complex, gamified reaching task. Clinical assessments of motor function and impairment, and brain activity (via functional magnetic resonance imaging) were obtained before and after training. RESULTS: While no differences in rsFC were observed in the control group, increased connectivity was observed in the sensorimotor network, linked to learning in the stroke group. Relative to healthy controls, a decrease in network efficiency was observed in the stroke group following training. CONCLUSIONS: Findings indicate that rsFC patterns related to learning observed after stroke reflect a shift toward a compensatory network configuration characterized by decreased network efficiency.


Subject(s)
Cerebral Cortex/physiopathology , Connectome , Motor Skills/physiology , Nerve Net/physiopathology , Practice, Psychological , Stroke/physiopathology , Adult , Aged , Aged, 80 and over , Cerebellum/diagnostic imaging , Cerebellum/physiopathology , Cerebral Cortex/diagnostic imaging , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Nerve Net/diagnostic imaging , Sensorimotor Cortex/diagnostic imaging , Sensorimotor Cortex/physiopathology , Stroke/diagnostic imaging
7.
J Neuroeng Rehabil ; 17(1): 158, 2020 12 01.
Article in English | MEDLINE | ID: mdl-33261623

ABSTRACT

BACKGROUND: In a recent high-profile case study, we used functional magnetic resonance imaging (fMRI) to monitor improvements in motor function related to neuroplasticity following rehabilitation for severe traumatic brain injury (TBI). The findings demonstrated that motor function improvements can occur years beyond current established limits. The current study extends the functional imaging investigation to characterize neuromodulation effects on neuroplasticity to further push the limits. METHODS: Canadian Soldier Captain (retired) Trevor Greene (TG) survived a severe open-TBI when attacked with an axe during a 2006 combat tour in Afghanistan. TG has since continued intensive daily rehabilitation to recover motor function, experiencing an extended plateau using conventional physical therapy. To overcome this plateau, we paired translingual neurostimulation (TLNS) with the continuing rehabilitation program. RESULTS: Combining TLNS with rehabilitation resulted in demonstrable clinical improvements along with corresponding changes in movement evoked electro-encephalography (EEG) activity. High-density magneto-encephalography (MEG) characterized cortical activation changes in corresponding beta frequency range (27 Hz). MEG activation changes corresponded with reduced interhemispheric inhibition in the post-central gyri regions together with increased right superior/middle frontal activation suggesting large scale network level changes. CONCLUSIONS: The findings provide valuable insight into the potential importance of non-invasive neuromodulation to enhance neuroplasticity mechanisms for recovery beyond the perceived limits of rehabilitation.


Subject(s)
Brain Injuries, Traumatic/rehabilitation , Brain/physiopathology , Electric Stimulation Therapy/methods , Neuronal Plasticity/physiology , Recovery of Function/physiology , Adult , Canada , Electric Stimulation Therapy/instrumentation , Electroencephalography , Humans , Magnetic Resonance Imaging , Magnetoencephalography/methods , Male , Physical Therapy Modalities
8.
Front Hum Neurosci ; 14: 347, 2020.
Article in English | MEDLINE | ID: mdl-33132868

ABSTRACT

Using a longitudinal case study design, we have tracked the recovery of motor function following severe traumatic brain injury (TBI) through a multimodal neuroimaging approach. In 2006, Canadian Soldier Captain (retired) Trevor Greene (TG) was attacked with an axe to the head while on tour in Afghanistan. TG continues intensive daily rehabilitation, which recently included the integration of physical therapy (PT) with neuromodulation using translingual neurostimulation (TLNS) to facilitate neuroplasticity. Recent findings with PT + TLNS demonstrated that recovery of motor function occurred beyond conventional time limits, currently extending past 14-years post-injury. To investigate whether PT + TLNS similarly resulted in associated cognitive function improvements, we examined event-related potentials (ERPs) with the brain vital signs framework. In parallel with motor function improvements, brain vital signs detected significant increases in basic attention (as measured by P300 response amplitude) and cognitive processing (as measured by contextual N400 response amplitude). These objective cognitive improvements corresponded with TG's self-reported improvements, including a noteworthy and consistent reduction in ongoing symptoms of post-traumatic stress disorder (PTSD). The findings provide valuable insight into the potential importance of non-invasive neuromodulation in cognitive rehabilitation, in addition to initial indications for physical rehabilitation.

9.
Front Hum Neurosci ; 14: 358, 2020.
Article in English | MEDLINE | ID: mdl-33117138

ABSTRACT

Background: Neuromodulation through translingual neurostimulation (TLNS) has been shown to initiate long-lasting processes of neuronal reorganization with a variety of outcomes (i.e., neuroplasticity). Non-invasive TLNS is increasingly accessible through the Portable Neuromodulation Stimulator (PoNS®), a medical device that delivers electrical stimulation to the tongue to activate the trigeminal (V) and facial (VII) cranial nerves. Anecdotal reports from previous clinical studies have suggested incidental improvements in cognitive function. To objectively explore this observation, we examined TLNS-related effects on the semantic N400 brain vital sign cognitive response during cognitive skills training in healthy individuals. Methods: Thirty-seven healthy volunteers were randomized to receive simultaneous TLNS (treatment) or no TLNS (control) while undergoing cognitive skills training. Cognitive training was conducted for two 20-min sessions (morning and afternoon/evening) over 3 consecutive days. Brain vital signs were evaluated at baseline, Day 1, and Day 3. Analyses focused on cognitive processing as measured by N400 changes in amplitude and latency. Results: Over the 3-day course of cognitive training, the N400 amplitude decreased significantly in the control group due to habituation (p = 0.028). In contrast, there was no significant change in the TLNS treatment group. Conclusion: TLNS led to a sustained N400 response during cognitive skills training, as measured by the brain's vital signs framework. The study findings suggest differential learning effects due to neuromodulation, consistent with increased attention and cognitive vigilance.

10.
J Neurol Phys Ther ; 44(2): 164-172, 2020 04.
Article in English | MEDLINE | ID: mdl-32168159

ABSTRACT

BACKGROUND AND PURPOSE: Therapeutic exercise improves balance and walking ability in individuals after stroke. The extent to which motor planning improves with therapeutic exercise is unknown. This case series examined how outpatient physical therapy affects motor planning and motor performance for stepping. CASE DESCRIPTION: Individuals poststroke performed self-initiated stepping before (baseline), after (postintervention), and 1 month after (retention) intervention. Amplitude and duration of the movement-related cortical potential (MRCP) was measured using an electroencephalograph from the Cz electrode. Electromyography (EMG) of biceps femoris (BF) was collected. Additionally, clinical measures of motor impairment and function were evaluated at all 3 time points by a blinded assessor. INTERVENTION: Two types of outpatient physical therapy were performed for 6 weeks: CONVENTIONAL (n = 3) and FAST (n = 4, Fast muscle Activation and Stepping Training). OUTCOMES: All 7 participants reduced MRCP duration, irrespective of the type of physical therapy. The MRCP amplitude and BF EMG onset changes were more variable. Clinical outcomes improved or were maintained for all participants. The extent of motor impairment was associated with MRCP amplitude. DISCUSSION: Changes in MRCP duration suggest that outpatient physical therapy may promote neuroplasticity of motor planning of stepping movements after stroke; however, a larger sample is needed to determine whether this finding is valid.This case series suggests motor planning for initiating stepping may improve after 6 weeks of outpatient physical therapy for persons with stroke.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A307).


Subject(s)
Cerebral Cortex/physiopathology , Exercise Therapy , Neuronal Plasticity/physiology , Stroke Rehabilitation , Stroke/physiopathology , Walking/physiology , Aged , Aged, 80 and over , Electroencephalography , Electromyography , Female , Humans , Male , Middle Aged , Movement/physiology
11.
Mov Disord ; 34(12): 1891-1900, 2019 12.
Article in English | MEDLINE | ID: mdl-31584222

ABSTRACT

BACKGROUND: The objective of this study was to examine the effects of aerobic exercise on evoked dopamine release and activity of the ventral striatum using positron emission tomography and functional magnetic resonance imaging in Parkinson's disease (PD). METHODS: Thirty-five participants were randomly allocated to a 36-session aerobic exercise or control intervention. Each participant underwent an functional magnetic resonance imaging scan while playing a reward task before and after the intervention to determine the effect of exercise on the activity of the ventral striatum in anticipation of reward. A subset of participants (n = 25) completed [11 C] raclopride positron emission tomography scans to determine the effect of aerobic exercise on repetitive transcranial magnetic stimulation-evoked release of endogenous dopamine in the dorsal striatum. All participants completed motor (MDS-UPDRS part III, finger tapping, Timed-up-and-go) and nonmotor assessments (Starkstein Apathy Scale, Beck Depression Inventory, reaction time, Positive and Negative Affect Schedule, Trail Making Test [A and B], and Montreal Cognitive Assessment) before and after the interventions. RESULTS: The aerobic group exhibited increased activity in the ventral striatum during functional magnetic resonance imaging in anticipation of 75% probability of reward (P = 0.01). The aerobic group also demonstrated increased repetitive transcranial magnetic stimulation-evoked dopamine release in the caudate nucleus (P = 0.04) and increased baseline nondisplaceable binding potential in the posterior putamen of the less affected repetitive transcranial magnetic stimulation-stimulated hemisphere measured by position emission tomography (P = 0.03). CONCLUSIONS: Aerobic exercise alters the responsivity of the ventral striatum, likely related to changes to the mesolimbic dopaminergic pathway, and increases evoked dopamine release in the caudate nucleus. This suggests that the therapeutic benefits of exercise are in part related to corticostriatal plasticity and enhanced dopamine release. © 2019 International Parkinson and Movement Disorder Society.


Subject(s)
Caudate Nucleus/metabolism , Dopamine/metabolism , Exercise/physiology , Parkinson Disease/metabolism , Ventral Striatum/metabolism , Aged , Aged, 80 and over , Caudate Nucleus/diagnostic imaging , Exercise Therapy , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Parkinson Disease/diagnostic imaging , Parkinson Disease/psychology , Positron-Emission Tomography , Prospective Studies , Tomography, X-Ray Computed , Transcranial Magnetic Stimulation , Ventral Striatum/diagnostic imaging
12.
J Neuroeng Rehabil ; 16(1): 60, 2019 05 27.
Article in English | MEDLINE | ID: mdl-31133021

ABSTRACT

BACKGROUND: Despite growing evidence of a critical link between neuromodulation technologies and neuroplastic recovery, the underlying mechanisms of these technologies remain elusive. OBJECTIVE: To investigate physiological evidence of central nervous system (CNS) changes in humans during translingual neurostimulation (TLNS). METHODS: We used high-density electroencephalography (EEG) to measure changes in resting brain activity before, during, and after high frequency (HF) and low frequency (LF) TLNS. RESULTS: Wavelet power analysis around Cz and microstate analysis revealed significant changes after 20 min of stimulation compared to baseline. A secondary effect of exposure order was also identified, indicating a differential neuromodulatory influence of HF TLNS relative to LF TLNS on alpha and theta signal power. CONCLUSIONS: These results further our understanding of the effects of TLNS on underlying resting brain activity, which in the long-term may contribute to the critical link between clinical effect and changes in brain activity.


Subject(s)
Brain/physiology , Electric Stimulation/methods , Tongue , Adult , Electroencephalography , Female , Humans , Male , Neuronal Plasticity/physiology , Rest/physiology
13.
Clin Neurophysiol ; 129(4): 787-796, 2018 04.
Article in English | MEDLINE | ID: mdl-29453170

ABSTRACT

OBJECTIVE: This study examined motor planning for stepping when the paretic leg was either stepping or standing (to step with the non-paretic leg), to understand whether difficulty with balance and walking post-stroke could be attributed to poor motor planning. METHODS: Individuals with stroke performed self-initiated stepping. Amplitude and duration of the movement-related cortical potential (MRCP) was measured from Cz. Electromyography (EMG) of biceps femoris (BF) and rectus femoris (RF) were collected. RESULTS: There were no differences between legs in stepping speed, MRCP or EMG parameters. The MRCPs when stepping with the paretic leg and the non-paretic leg were correlated. When the paretic leg was stepping, the MRCP amplitude correlated with MRCP duration, indicating a longer planning time was accompanied by higher cognitive effort. Slow steppers had larger MRCP amplitudes stepping with the paretic leg and longer MRCP durations stepping with the non-paretic leg. CONCLUSIONS: MRCP measures suggest that motor planning for initiating stepping are similar regardless of which limb is stepping. Individuals who stepped slowly had greater MRCP amplitudes and durations for planning. SIGNIFICANCE: Individuals who step slowly may require more time and effort to plan a movement, which may compromise their safety in the community.


Subject(s)
Electromyography/methods , Intention , Motor Cortex/physiology , Movement/physiology , Stroke/physiopathology , Walking/physiology , Aged , Aged, 80 and over , Cerebral Cortex , Electroencephalography/methods , Female , Humans , Male , Middle Aged , Postural Balance/physiology , Stroke/diagnosis , Walking/psychology
15.
Neuroimage Clin ; 14: 344-353, 2017.
Article in English | MEDLINE | ID: mdl-28229041

ABSTRACT

The relationships between impairment, function, arm use and underlying brain structure following stroke remain unclear. Although diffusion weighted imaging is useful in broadly assessing white matter structure, it has limited utility in identifying specific underlying neurobiological components, such as myelin. The purpose of the present study was to explore relationships between myelination and impairment, function and activity in individuals with chronic stroke. Assessments of paretic upper-extremity impairment and function were administered, and 72-hour accelerometer based activity monitoring was conducted on 19 individuals with chronic stroke. Participants completed a magnetic resonance imaging protocol that included a high resolution T1 anatomical scan and a multi-component T2 relaxation imaging scan to quantify myelin water fraction (MWF). MWF was automatically parcellated from pre- and post-central subcortical regions of interest and quantified as an asymmetry ratio (contralesional/ipsilesional). Cluster analysis was used to group more and less impaired individuals based on Fugl-Meyer upper extremity scores. A significantly higher precentral MWF asymmetry ratio was found in the more impaired group compared to the less impaired group (p < 0.001). There were no relationships between MWF asymmetry ratio and upper-limb use. Stepwise multiple linear regression identified precentral MWF asymmetry as the only variable to significantly predict impairment and motor function in the upper extremity (UE). These results suggest that asymmetric myelination in a motor specific brain area is a significant predictor of upper-extremity impairment and function in individuals with chronic stroke. As such, myelination may be utilized as a more specific marker of the neurobiological changes that predict long term impairment and recovery from stroke.


Subject(s)
Functional Laterality/physiology , Motor Disorders/etiology , Myelin Sheath/pathology , Stroke , Accelerometry , Aged , Aged, 80 and over , Analysis of Variance , Brain Mapping , Cerebral Cortex/diagnostic imaging , Cerebral Cortex/pathology , Female , Humans , Image Processing, Computer-Assisted , Linear Models , Magnetic Resonance Imaging , Male , Middle Aged , Motor Disorders/diagnostic imaging , Myelin Sheath/metabolism , Stroke/complications , Stroke/diagnostic imaging , Stroke/physiopathology , Upper Extremity/physiopathology
16.
Neurorehabil Neural Repair ; 31(1): 95-104, 2017 01.
Article in English | MEDLINE | ID: mdl-27511047

ABSTRACT

BACKGROUND: Conventionally, change in motor performance is quantified with discrete measures of behavior taken pre- and postpractice. As a high degree of movement variability exists in motor performance after stroke, pre- and posttesting of motor skill may lack sensitivity to predict potential for motor recovery. OBJECTIVE: Evaluate the use of predictive models of motor learning based on individual performance curves and clinical characteristics of motor function in individuals with stroke. METHODS: Ten healthy and fourteen individuals with chronic stroke performed a continuous joystick-based tracking task over 6 days, and at a 24-hour delayed retention test, to assess implicit motor sequence learning. RESULTS: Individuals with chronic stroke demonstrated significantly slower rates of improvements in implicit sequence-specific motor performance compared with a healthy control (HC) group when root mean squared error performance data were fit to an exponential function. The HC group showed a positive relationship between a faster rate of change in implicit sequence-specific motor performance during practice and superior performance at the delayed retention test. The same relationship was shown for individuals with stroke only after accounting for overall motor function by including Wolf Motor Function Test rate in our model. CONCLUSION: Nonlinear information extracted from multiple time points across practice, specifically the rate of motor skill acquisition during practice, relates strongly with changes in motor behavior at the retention test following practice and could be used to predict optimal doses of practice on an individual basis.


Subject(s)
Learning , Motor Activity , Stroke/psychology , Aged , Analysis of Variance , Arm , Female , Humans , Male , Middle Aged , Neuropsychological Tests , Nonlinear Dynamics , Regression Analysis , Stroke/physiopathology , Stroke Rehabilitation
17.
Exp Brain Res ; 235(1): 293-304, 2017 01.
Article in English | MEDLINE | ID: mdl-27709269

ABSTRACT

While concurrent augmented visual feedback of the center of pressure (COP) or center of gravity (COG) can improve quiet standing balance control, it is not known whether such feedback improves reactive balance control. Additionally, it is not known whether feedback of the COP or COG is superior. This study aimed to determine whether (1) concurrent augmented feedback can improve reactive balance control, and (2) feedback of the COP or COG is more effective. Forty-eight healthy older adults (60-75 years old) were randomly allocated to one of three groups: feedback of the COP, feedback of the COG, or no feedback. The task was to maintain standing while experiencing 30 s of continuous pseudo-random perturbations delivered by a moving platform. Participants completed 25 trials with or without feedback (acquisition), immediately followed by 5 trials without feedback (immediate transfer); 5 trials without feedback were completed after a 24-h delay (delayed transfer). The root mean square error (RMSE) of COP-COG, electrodermal level, and co-contraction index were compared between the groups and over time. All three groups reduced RMSE and co-contraction index from the start of the acquisition to the transfer tests, and there were no significant between-group differences in RMSE or co-contraction on the transfer tests. Therefore, all three groups learned the task equally well, and improved balance was achieved with practice via a more efficient control strategy. The two feedback groups reduced electrodermal level with practice, but the no-feedback group did not, suggesting that feedback may help to reduce anxiety.


Subject(s)
Aging/physiology , Feedback, Sensory/physiology , Postural Balance/physiology , Transfer, Psychology/physiology , Aged , Analysis of Variance , Electromyography , Female , Gravitation , Humans , Male , Middle Aged , Muscle Contraction/physiology , Muscle, Skeletal/physiology , Pressure , Time Factors
18.
Neural Plast ; 2016: 7526135, 2016.
Article in English | MEDLINE | ID: mdl-27293906

ABSTRACT

Experience-dependent structural changes are widely evident in gray matter. Using diffusion weighted imaging (DWI), the neuroplastic effect of motor training on white matter in the brain has been demonstrated. However, in humans it is not known whether specific features of white matter relate to motor skill acquisition or if these structural changes are associated to functional network connectivity. Myelin can be objectively quantified in vivo and used to index specific experience-dependent change. In the current study, seventeen healthy young adults completed ten sessions of visuomotor skill training (10,000 total movements) using the right arm. Multicomponent relaxation imaging was performed before and after training. Significant increases in myelin water fraction, a quantitative measure of myelin, were observed in task dependent brain regions (left intraparietal sulcus [IPS] and left parieto-occipital sulcus). In addition, the rate of motor skill acquisition and overall change in myelin water fraction in the left IPS were negatively related, suggesting that a slower rate of learning resulted in greater neuroplastic change. This study provides the first evidence for experience-dependent changes in myelin that are associated with changes in skilled movements in healthy young adults.


Subject(s)
Learning/physiology , Motor Skills/physiology , Myelin Sheath/physiology , Neuronal Plasticity/physiology , White Matter/physiology , Adult , Diffusion Magnetic Resonance Imaging/methods , Female , Humans , Male , Psychomotor Performance/physiology , Young Adult
19.
Neurosci Lett ; 618: 25-30, 2016 Apr 08.
Article in English | MEDLINE | ID: mdl-26940237

ABSTRACT

TMS-evoked cortical responses can be measured using simultaneous electroencephalography (TMS-EEG) to directly quantify cortical connectivity in the human brain. The purpose of this study was to evaluate interhemispheric cortical connectivity between the primary motor cortices (M1s) in participants with chronic stroke and controls using TMS-EEG. Ten participants with chronic stroke and four controls were tested. TMS-evoked responses were recorded at rest and during a typical TMS assessment of transcallosal inhibition (TCI). EEG recordings from peri-central gyral electrodes (C3 and C4) were evaluated using imaginary phase coherence (IPC) analyses to quantify levels of effective interhemispheric connectivity. Significantly increased TMS-evoked beta (15-30Hz frequency range) IPC was observed in the stroke group during ipsilesional M1 stimulation compared to controls during TCI assessment but not at rest. TMS-evoked beta IPC values were associated with TMS measures of transcallosal inhibition across groups. These results suggest TMS-evoked EEG responses can index abnormal effective interhemispheric connectivity in chronic stroke.


Subject(s)
Motor Cortex/physiopathology , Stroke/physiopathology , Transcranial Magnetic Stimulation , Aged , Case-Control Studies , Chronic Disease , Electroencephalography , Female , Humans , Male , Middle Aged
20.
Phys Ther ; 95(10): 1423-32, 2015 Oct.
Article in English | MEDLINE | ID: mdl-25929533

ABSTRACT

Attention and planning can be altered by stroke, which can influence motor performance. Although the influence of these factors on recovery from stroke has been explored for the upper extremity (UE), their impact on balance and gait are unknown. This perspective article presents evidence that altered motor and visuospatial attention influence motor planning of voluntary goal-directed movements poststroke, potentially affecting balance and gait. Additionally, specific strategies for rehabilitation of balance and gait poststroke in the presence of these factors are discussed. Visuospatial attention selects relevant sensory information and supports the preparation of responses to this information. Motor attentional impairments may produce difficulty with selecting appropriate motor feedback, potentially contributing to falls. An original theoretical model is presented for a network of brain regions supporting motor and visuospatial attention, as well as motor planning of voluntary movements. Stroke may influence this functional network both locally and distally, interfering with input or output of the anatomical or functional regions involved and affecting voluntary movements. Although there is limited research directly examining leg function, evidence suggests alterations in motor and visuospatial attention influence motor planning and have a direct impact on performance of gait and balance. This model warrants testing comparing healthy adults with individuals with stroke.


Subject(s)
Attention/physiology , Psychomotor Performance/physiology , Sensorimotor Cortex/physiopathology , Spatial Processing/physiology , Stroke/physiopathology , Stroke/psychology , Gait/physiology , Humans , Postural Balance/physiology , Recovery of Function , Stroke Rehabilitation
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