Publications by authors named "Jens Bo Nielsen"

121 Publications

Transcranial Alternating Current Stimulation of the Primary Motor Cortex after Skill Acquisition Improves Motor Memory Retention in Humans: A Double-Blinded Sham-Controlled Study.

Cereb Cortex Commun 2020 6;1(1):tgaa047. Epub 2020 Aug 6.

Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark.

Consolidation leading to retention of motor memory following motor practice involves activity-dependent plastic processes in the corticospinal system. To investigate whether beta-band transcranial alternating current stimulation (tACS) applied immediately following skill acquisition can enhance ongoing consolidation processes and thereby motor skill retention 20 adults participated in a randomized, double-blinded, sham-controlled study. Participants received tACS at peak beta-band corticomuscular coherence (CMC) frequency or sham tACS for 10 min following practice of a visuomotor ankle dorsiflexion task. Performance was measured as the average percentage time on target. Electroencephalograhy (EMG) was measured at Cz and EMG from the right tibialis anterior muscle. CMC and intramuscular coherence (IMC) were estimated during 2-min tonic dorsiflexion. Motor skill retention was tested 1 and 7 days after motor practice. From the end of motor practice to the retention tests, motor performance improved more in the tACS group compared with the sham tACS group after 1 ( = 0.05) and 7 days ( < 0.001). At both retention tests, beta-band IMC increased in the tACS group compared with post-tACS. Beta-band CMC increased in the tACS group at retention day 1 compared with post-tACS. Changes in CMC but not IMC were correlated with performance 1 and 7 days following practice. This study shows that tACS applied at beta-band CMC frequency improves consolidation following visuomotor practice and increases beta-band CMC and IMC. We propose that oscillatory beta activity in the corticospinal system may facilitate consolidation of the motor skill.
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http://dx.doi.org/10.1093/texcom/tgaa047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152838PMC
August 2020

COpenhagen Neuroplastic TRaining Against Contractures in Toddlers (CONTRACT): protocol of an open-label randomised clinical trial with blinded assessment for prevention of contractures in infants with high risk of cerebral palsy.

BMJ Open 2021 07 6;11(7):e044674. Epub 2021 Jul 6.

Department of Neuroscience, University of Copenhagen Faculty of Health Sciences, Copenhagen, Denmark.

Introduction: Contractures are frequent causes of reduced mobility in children with cerebral palsy (CP) already at the age of 2-3 years. Reduced muscle use and muscle growth have been suggested as key factors in the development of contractures, suggesting that effective early prevention may have to involve stimuli that can facilitate muscle growth before the age of 1 year. The present study protocol was developed to assess the effectiveness of an early multicomponent intervention, CONTRACT, involving family-oriented and supervised home-based training, diet and electrical muscle stimulation directed at facilitating muscle growth and thus reduce the risk of contractures in children at high risk of CP compared with standard care.

Methods And Analysis: A two-group, parallel, open-label randomised clinical trial with blinded assessment (n=50) will be conducted. Infants diagnosed with CP or designated at high risk of CP based on abnormal neuroimaging or absent fidgety movement determined as part of General Movement Assessment, age 9-17 weeks corrected age (CA) will be recruited. A balanced 1:1 randomisation will be made by a computer. The intervention will last for 6 months aiming to support parents in providing daily individualised, goal-directed activities and primarily in lower legs that may stimulate their child to move more and increase muscle growth. Guidance and education of the parents regarding the nutritional benefits of docosahexaenic acid (DHA) and vitamin D for the developing brain and muscle growth will be provided. Infants will receive DHA drops as nutritional supplements and neuromuscular stimulation to facilitate muscle growth. The control group will receive standard care as offered by their local hospital or community. Outcome measures will be taken at 9, 12, 18, 24, 36 and 48 months CA. Primary and secondary outcome measure will be lower leg muscle volume and stiffness of the triceps surae musculotendinous unit together with infant motor profile, respectively.

Ethics And Dissemination: Full approval from the local ethics committee, Danish Committee System on Health Research Ethics, Region H (H-19041562). Experimental procedures conform with the Declaration of Helsinki.

Trial Registration Number: NCT04250454.

Expected Recruitment Period: 1 January 2021-1 January 2025.
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http://dx.doi.org/10.1136/bmjopen-2020-044674DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8261878PMC
July 2021

Increased Ankle Plantar Flexor Stiffness Is Associated With Reduced Mechanical Response to Stretch in Adults With CP.

Front Bioeng Biotechnol 2021 25;9:604071. Epub 2021 Mar 25.

School of Applied Health Sciences, Griffith University, Brisbane, QLD, Australia.

Hyperexcitable stretch reflexes are often not present despite of other signs of spasticity in people with brain lesion. Here we looked for evidence that increased resistance to length change of the plantar flexor muscle-fascicles may contribute to a reduction in the stretch reflex response in adults with cerebral palsy (CP). A total of 17 neurologically intact (NI) adults (mean age 36.1; 12 female) and 13 ambulant adults with CP (7 unilateral; mean age 33.1; 5 female) participated in the study. Subjects were seated in a chair with the examined foot attached to a foot plate, which could be moved by a computer-controlled electromotor. An ultrasound probe was placed over the medial aspect of the leg to measure the length of medial gastrocnemius muscle fascicles. Slow (7 deg/s) and fast (200 deg/s) stretches with amplitude 6 deg of the plantar flexors were applied over an ankle range of 70 deg at 10 deg intervals between 60 and 130 deg plantarflexion. It was checked by EMG electrodes that the slow stretches were sufficiently slow not to elicit any activity and that the fast stretches were sufficiently quick to elicit a maximal stretch reflex in both groups. The torque elicited by the stretches was measured together with changes in the length of medial gastrocnemius muscle fascicles. Muscle fascicles increased significantly in length with increasing dorsiflexion position in both populations ( < 0.001), but the fascicles were shorter in the CP population at all positions. Slow stretches elicited significantly larger torque and significantly smaller length change of muscle fascicles as the ankle joint position was moved more towards dorsiflexion in CP than in NI ( < 0.001). Fast stretches elicited larger torque responses at ankle joint positions of 80-100 deg in the NI than in the CP group ( < 0.01). A significant negative correlation was observed between the torque response and muscle fascicle length change to slow stretch in CP ( < 0.05), but not in NI. These findings support that increased passive resistance of the ankle plantar flexor muscle-tendon unit and development of contractures may conceal stretch reflex response in adults with CP. We argue that this should be taken into account in the neurological examination of spasticity.
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http://dx.doi.org/10.3389/fbioe.2021.604071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026870PMC
March 2021

Nonsurgical Treatment Options for Muscle Contractures in Individuals With Neurologic Disorders: A Systematic Review With Meta-Analysis.

Arch Rehabil Res Clin Transl 2021 Mar 13;3(1):100104. Epub 2021 Jan 13.

Department of Neuroscience, University of Copenhagen, Copenhagen.

Objective: To investigate whether nonsurgical treatment can reduce muscle contractures in individuals with neurologic disorders. The primary outcome measure was muscle contractures measured as joint mobility or passive stiffness.

Data Sources: Embase, MEDLINE, Cumulative Index to Nursing and Allied Health, and Physiotherapy Evidence Database in June-July 2019 and again in July 2020.

Study Selection: The search resulted in 8020 records, which were screened by 2 authors based on our patient, intervention, comparison, outcome criteria. We included controlled trials of nonsurgical interventions administered to treat muscle contractures in individuals with neurologic disorders.

Data Extraction: Authors, participant characteristics, intervention details, and joint mobility/passive stiffness before and after intervention were extracted. We assessed trials for risk of bias using the Downs and Black checklist. We conducted meta-analyses investigating the short-term effect on joint mobility using a random-effects model with the pooled effect from randomized controlled trials (RCTs) as the primary outcome. The minimal clinically important effect was set at 5°.

Data Synthesis: A total of 70 trials (57 RCTs) were eligible for inclusion. Stretch had a pooled effect of 3° (95% CI, 1-4°; prediction interval (PI)=-2 to 7°; =66%; <.001), and robot-assisted rehabilitation had an effect of 1 (95% CI, 0-2; PI=-8 to 9; =73%; =.03). We found no effect of shockwave therapy (=.56), physical activity (=.27), electrical stimulation (=.11), or botulinum toxin (=.13). Although trials were generally of moderate to high quality according to the Downs and Black checklist, only 18 of the 70 trials used objective measures of muscle contractures. In 23 trials, nonobjective measures were used without use of assessor-blinding.

Conclusions: We did not find convincing evidence supporting the use of any nonsurgical treatment option. We recommend that controlled trials using objective measures of muscle contractures and a sufficiently large number of participants be performed.
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http://dx.doi.org/10.1016/j.arrct.2021.100104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7984980PMC
March 2021

Motor-learning based activities may improve functional ability in adults with severe cerebral palsy: A controlled pilot study.

NeuroRehabilitation 2021 ;48(3):273-283

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

Background: Cerebral palsy (CP) is a neurodevelopmental disturbance characterized by impaired control of movement. Function often decreases and 15% of adults are classified as severely affected (Gross Motor Function Classification Scale III-V). Little is known about interventions that aim to improve functional abilities in this population.

Objective: To evaluate a 12-week intervention based on motor learning principles on functional ability in adults with severe CP.

Methods: 16 adults (36±10 years, GMFCS III-V) were enrolled and divided into an intervention group (Active group) and a standard care group (Control group). Primary outcome measure was Gross Motor Function Measure (GMFM-88). Secondary measures were neurological status. The Active group were measured at baseline, after the intervention and at one-month follow-up. The Control group were measured at baseline and after one month.

Results: Analysis showed statistically significant improvement in GMFM-88 for the Active group from baseline to post assessment compared with the Control group (group difference: 5 points, SE 14.5, p = 0.008, CI: 1.2 to 8.7). Improvements were maintained at follow-up. Results from the neurological screening showed no clear tendencies.

Conclusions: The study provides support that activities based on motor learning principles may improve gross motor function in adults with severe CP.
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http://dx.doi.org/10.3233/NRE-201581DOI Listing
June 2021

Gene expressions in cerebral palsy subjects reveal structural and functional changes in the gastrocnemius muscle that are closely associated with passive muscle stiffness.

Cell Tissue Res 2021 May 30;384(2):513-526. Epub 2021 Jan 30.

Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark.

Cerebral palsy (CP) is a non-progressive motor disorder that affects posture and gait due to contracture development. The purpose of this study is to analyze a possible relation between muscle stiffness and gene expression levels in muscle tissue of children with CP. Next-generation sequencing (NGS) of gene transcripts was carried out in muscle biopsies from gastrocnemius muscle (n = 13 children with CP and n = 13 typical developed (TD) children). Passive stiffness of the ankle plantarflexors was measured. Structural changes of the basement membranes and the sarcomere length were measured. Twelve pre-defined gene target sub-categories of muscle function, structure and metabolism showed significant differences between muscle tissue of CP and TD children. Passive stiffness was significantly correlated to gene expression levels of HSPG2 (p = 0.02; R = 0.67), PRELP (p = 0.002; R = 0.84), RYR3 (p = 0.04; R = 0.66), C COL5A3 (p = 0.0007; R = 0.88), ASPH (p = 0.002; R = 0.82) and COL4A6 (p = 0.03; R = 0.97). Morphological differences in the basement membrane were observed between children with CP and TD children. The sarcomere length was significantly increased in children with CP when compared with TD (p = 0.04). These findings show that gene targets in the categories: calcium handling, basement membrane and collagens, were significantly correlated to passive muscle stiffness. A Reactome pathway analysis showed that pathways involved in DNA repair, ECM proteoglycans and ion homeostasis were amongst the most upregulated pathways in CP, while pathways involved in collagen fibril crosslinking, collagen fibril assembly and collagen turnover were amongst the most downregulated pathways when compared with TD children. These results underline that contracture formation and motor impairment in CP is an interplay between multiple factors.
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http://dx.doi.org/10.1007/s00441-020-03399-zDOI Listing
May 2021

A simple, clinically applicable motor learning protocol to increase push-off during gait: A proof-of-concept.

PLoS One 2021 19;16(1):e0245523. Epub 2021 Jan 19.

Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Quebec City, Quebec, Canada.

Objective: Task-specific training is often used in functional rehabilitation for its potential to improve performance at locomotor tasks in neurological populations. As push-off impairment are often seen with these patients, this functional approach shows potential to retrain gait overground to normalize the gait pattern and retrain the ability to improve gait speed. The main objective of this project was to validate, in healthy participants, a simple, low-cost push-off retraining protocol based on task-specific training that could be implemented during overground walking in the clinic.

Methods: 30 healthy participants walked in an 80-meter long corridor before, during, and after the application of an elastic resistance to the right ankle. Elastic tubing attached to the front of a modified ankle-foot orthosis delivered the resistance during push-off. Relative ankle joint angular displacements were recorded bilaterally and continuously during each walking condition.

Results: On the resisted side, participants presented aftereffects (increased peak plantarflexion angle from 13.4±4.2° to 20.0±6.4°, p<0.0001 and increased peak plantarflexion angular velocity from 145.8±22.7°/s to 174.4±37.4°/s, p<0.0001). On the non-resisted side, aftereffects were much smaller than on the resisted side suggesting that the motor learning process was mainly specific to the trained leg.

Conclusion: This study shows the feasibility of modifying push-off kinematics using an elastic resistance applied at the ankle while walking overground. This approach represents an interesting venue for future gait rehabilitation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245523PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815130PMC
June 2021

Philanthropic funding in cerebral palsy research: translating new knowledge into improved quality of life.

Dev Med Child Neurol 2021 02;63(2):125

The Lundbeck Foundation, Copenhagen, Denmark.

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http://dx.doi.org/10.1111/dmcn.14718DOI Listing
February 2021

Sustained involuntary muscle activity in cerebral palsy and stroke: same symptom, diverse mechanisms.

Brain Commun 2019 25;1(1):fcz037. Epub 2019 Nov 25.

Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark.

Individuals with lesions of central motor pathways frequently suffer from sustained involuntary muscle activity. This symptom shares clinical characteristics with dystonia but is observable in individuals classified as spastic. The term spastic dystonia has been introduced, although the underlying mechanisms of involuntary activity are not clarified and vary between individuals depending on the disorder. This study aimed to investigate the nature and pathophysiology of sustained involuntary muscle activity in adults with cerebral palsy and stroke. Seventeen adults with cerebral palsy (Gross Motor Function Classification System I-V), 8 adults with chronic stroke and 14 control individuals participated in the study. All individuals with cerebral palsy or stroke showed increased resistance to passive movement with Modified Ashworth Scale >1. Two-minute surface EMG recordings were obtained from the biceps muscle during attempted rest in three positions of the elbow joint; a maximally flexed position, a 90-degree position and a maximally extended position. Cross-correlation analysis of sustained involuntary muscle activity from individuals with cerebral palsy and stroke, and recordings of voluntary isometric contractions from control individuals were performed to examine common synaptic drive. In total, 13 out of 17 individuals with cerebral palsy and all 8 individuals with stroke contained sustained involuntary muscle activity. In individuals with cerebral palsy, the level of muscle activity was not affected by the joint position. In individuals with stroke, the level of muscle activity significantly ( < 0.05) increased from the flexed position to the 90 degree and extended position. Cumulant density function indicated significant short-term synchronization of motor unit activities in all recordings. All groups exhibited significant coherence in the alpha (6-15 Hz), beta (16-35 Hz) and early gamma band (36-60 Hz). The cerebral palsy group had lower alpha band coherence estimates, but higher gamma band coherence estimates compared with the stroke group. Individuals with increased resistance to passive movement due to cerebral palsy or stroke frequently suffer sustained involuntary muscle activity, which cannot exclusively be described by spasticity. The sustained involuntary muscle activity in both groups originated from a common synaptic input to the motor neuron pool, but the generating mechanisms could differ between groups. In cerebral palsy it seemed to originate more from central mechanisms, whereas peripheral mechanisms likely play a larger role in stroke. The sustained involuntary muscle activity should not be treated simply like the spinal stretch reflex mediated symptom of spasticity and should not either be treated identically in both groups.
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http://dx.doi.org/10.1093/braincomms/fcz037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7531180PMC
November 2019

Long-term motor skill training with individually adjusted progressive difficulty enhances learning and promotes corticospinal plasticity.

Sci Rep 2020 09 24;10(1):15588. Epub 2020 Sep 24.

Department of Nutrition Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.

Motor skill acquisition depends on central nervous plasticity. However, behavioural determinants leading to long lasting corticospinal plasticity and motor expertise remain unexplored. Here we investigate behavioural and electrophysiological effects of individually tailored progressive practice during long-term motor skill training. Two groups of participants practiced a visuomotor task requiring precise control of the right digiti minimi for 6 weeks. One group trained with constant task difficulty, while the other group trained with progressively increasing task difficulty, i.e. continuously adjusted to their individual skill level. Compared to constant practice, progressive practice resulted in a two-fold greater performance at an advanced task level and associated increases in corticospinal excitability. Differences were maintained 8 days later, whereas both groups demonstrated equal retention 14 months later. We demonstrate that progressive practice enhances motor skill learning and promotes corticospinal plasticity. These findings underline the importance of continuously challenging patients and athletes to promote neural plasticity, skilled performance, and recovery.
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http://dx.doi.org/10.1038/s41598-020-72139-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518278PMC
September 2020

Sentence-Based Experience Logging in New Hearing Aid Users.

Am J Audiol 2020 Sep 18;29(3S):631-637. Epub 2020 Sep 18.

Department of Electronic Systems, Aalborg University, Denmark.

Purpose The aim of this study was to develop a tool to gain insight into the daily experiences of new hearing aid users and to shed light on aspects of aided performance that may not be unveiled through standard questionnaires. Method The tool is developed based on clinical observations, patient experiences, expert involvement, and existing validated hearing rehabilitation questionnaires. Results An online tool for collecting data related to hearing aid use was developed. The tool is based on 453 prefabricated sentences representing experiences within 13 categories related to hearing aid use. Conclusions The tool has the potential to reflect a wide range of individual experiences with hearing aid use, including auditory and nonauditory aspects. These experiences may hold important knowledge for both the patient and the professional in the hearing rehabilitation process.
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http://dx.doi.org/10.1044/2020_AJA-19-00077DOI Listing
September 2020

A Danish Sentence Corpus for Assessing Speech Recognition in Noise in School-Age Children.

Trends Hear 2020 Jan-Dec;24:2331216520942392

Institute of Clinical Research, University of Southern Denmark.

For the audiological assessment of the speech-in-noise abilities of children with normal or impaired hearing, appropriate test materials are required. However, in Denmark, no standardized materials exist. The purpose of this study was to develop a Danish sentence corpus suitable for testing school-age children. Based on the 600 validated test sentences from the Danish DAT (agmar, sta, or ine) corpus, 11 test lists comprising 20 sentences each were carefully constructed. These lists were evaluated in terms of their perceptual similarity and reliability with a group of 20 typically developing, normal-hearing children aged 6 to 12 years. Using stationary speech-shaped noise and diotic stimulus presentation, speech recognition thresholds (SRTs) were measured twice per list and participant at two separate visits. The analyses showed that six test lists were perceptually equivalent. These lists are characterized by a grand average SRT of -2.6 dB signal-to-noise ratio, a test-retest improvement of 0.6 dB, and a within-subject standard deviation of 1.1 dB signal-to-noise ratio. The other lists were characterized by slightly higher SRTs, slightly larger training effects, and slightly larger measurement uncertainty, but were otherwise also usable. Overall, it is therefore concluded that the developed corpus is suited for assessing speech recognition in noise in Danish 6- to 12-year olds. The corpus is publicly available.
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http://dx.doi.org/10.1177/2331216520942392DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466876PMC
November 2020

Immobilization leads to reduced stretch reflexes but increased central reflex gain in the rat.

J Neurophysiol 2020 09 12;124(3):985-993. Epub 2020 Aug 12.

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

Plastic adaptations are known to take place in muscles, tendons, joints, and the nervous system in response to changes in muscle activity. However, few studies have addressed how these plastic adaptations are related. Thus this study focuses on changes in the mechanical properties of the ankle plantarflexor muscle-tendon unit, stretch reflex activity, and spinal neuronal pathways in relation to cast immobilization. The left rat hindlimb from toes to hip was immobilized with a plaster cast for 1, 2, 4, or 8 wk followed by acute electrophysiological recordings to investigate muscle stiffness and stretch reflex torque. Moreover, additional acute experiments were performed after 4 wk of immobilization to investigate changes in the central gain of the stretch reflex. Monosynaptic reflexes (MSR) were recorded from the L4 and L5 ventral roots following stimulation of the corresponding dorsal roots. Rats developed reduced range of movement in the ankle joint 2 wk after immobilization. This was accompanied by significant increases in the stiffness of the muscle-tendon complex as well as an arthrosis at the ankle joint at 4 and 8 wk following immobilization. Stretch reflexes were significantly reduced at 4-8 wk following immobilization. This was associated with increased central gain of the stretch reflex. These data show that numerous interrelated plastic changes occur in muscles, connective tissue, and the central nervous system in response to changes in muscle use. The findings provide an understanding of coordinated adaptations in multiple tissues and have important implications for prevention and treatment of the negative consequences of immobilization following injuries of the nervous and musculoskeletal systems. Immobilization leads to multiple simultaneous adaptive changes in muscle, connective tissue, and central nervous system.
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http://dx.doi.org/10.1152/jn.00748.2019DOI Listing
September 2020

The benefits of strength training in cerebral palsy.

Dev Med Child Neurol 2020 11 8;62(11):1232. Epub 2020 Aug 8.

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

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http://dx.doi.org/10.1111/dmcn.14625DOI Listing
November 2020

Directed connectivity between primary and premotor areas underlying ankle force control in young and older adults.

Neuroimage 2020 09 22;218:116982. Epub 2020 May 22.

Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

The control of ankle muscle force is an integral component of walking and postural control. Aging impairs the ability to produce force steadily and accurately, which can compromise functional capacity and quality of life. Here, we hypothesized that reduced force control in older adults would be associated with altered cortico-cortical communication within a network comprising the primary motor area (M1), the premotor cortex (PMC), parietal, and prefrontal regions. We examined electroencephalographic (EEG) responses from fifteen younger (20-26 ​yr) and fifteen older (65-73 ​yr) participants during a unilateral dorsiflexion force-tracing task. Dynamic Causal Modelling (DCM) and Parametric Empirical Bayes (PEB) were used to investigate how directed connectivity between contralateral M1, PMC, parietal, and prefrontal regions was related to age group and precision in force production. DCM and PEB analyses revealed that the strength of connections between PMC and M1 were related to ankle force precision and differed by age group. For young adults, bidirectional PMC-M1 coupling was negatively related to task performance: stronger backward M1-PMC and forward PMC-M1 coupling was associated with worse force precision. The older group exhibited deviations from this pattern. For the PMC to M1 coupling, there were no age-group differences in coupling strength; however, within the older group, stronger coupling was associated with better performance. For the M1 to PMC coupling, older adults followed the same pattern as young adults - with stronger coupling accompanied by worse performance - but coupling strength was lower than in the young group. Our results suggest that bidirectional M1-PMC communication is related to precision in ankle force production and that this relationship changes with aging. We argue that the observed differences reflect compensatory reorganization that counteracts age-related sensorimotor declines and contributes to maintaining performance.
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http://dx.doi.org/10.1016/j.neuroimage.2020.116982DOI Listing
September 2020

Spastic movement disorder: should we forget hyperexcitable stretch reflexes and start talking about inappropriate prediction of sensory consequences of movement?

Exp Brain Res 2020 Aug 7;238(7-8):1627-1636. Epub 2020 May 7.

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

Spastic movement disorder is characterized by reduced ability to selectively activate muscles with significant co-activation of antagonist muscles. It has traditionally been thought that hyperexcitable stretch reflexes have a central role in the pathophysiology and the clinical manifestations of the disorder. Here we argue that the main functional challenges for persons with spastic movement disorder are related to contractures, paresis, weak muscles and inappropriate central motor commands, whereas hyperexcitable reflexes play no or only an insignificant functional role. Co-activation of antagonist muscles and stiff posture and gait may rather be adaptations that aim to ensure joint and postural stability due to insufficient muscle strength. Aberrant (involuntary) muscle activity is likely related to an inadequate prediction of the sensory consequences of movement and a resulting impairment of muscle coordination. We argue that improvement of functional muscle strength and muscle coordination following central motor lesions may be achieved by optimizing integration of somatosensory information into central feedforward motor programs, whereas anti-spastic therapy that aims to reduce reflex activity may be less efficient. This opens for novel investigations into new treatment strategies that may improve functional control of movement and prevent reduced joint mobility in people with brain lesions.
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http://dx.doi.org/10.1007/s00221-020-05792-0DOI Listing
August 2020

Gait training facilitates push-off and improves gait symmetry in children with cerebral palsy.

Hum Mov Sci 2020 Feb 6;69:102565. Epub 2020 Jan 6.

Department of Neuroscience, Univ. of Copenhagen, Copenhagen, Denmark.

Background: Human walking involves a rapid and powerful contraction of ankle plantar flexors during push-off in late stance.

Objective: Here we investigated whether impaired push-off force contributes to gait problems in children with cerebral palsy (CP) and whether it may be improved by intensive gait training.

Methods: Sixteen children with CP (6-15 years) and fourteen typically developing (TD) children (4-15 years) were recruited. Foot pressure was measured by insoles and gait kinematics were recorded by 3-dimensional video analysis during treadmill and overground walking. The peak derivative of ground reaction force at push off (dPF) was calculated from the foot pressure measurements. Maximal voluntary plantar flexion (MVC) was measured while seated. Measurements were performed before and after a control period and after 4 weeks of 30 minutes daily inclined treadmill training.

Results: dPF and MVC were significantly lower in children with CP on the most affected (MA) as compared to TD children (p < .001). dPF was lower on the MA leg as compared to the less affected (LA) leg in children with CP (p < .05). Following gait training, increases in dPF (p < .001) and MVC (p < .01) were observed for the MA leg. Following gait training children with CP showed similar timing of dPF and similar stance phase duration on both legs indicating improved symmetry of gait. These effects were also shown during overground walking.

Conclusion: Impaired ability to voluntarily activate ankle plantar flexors and produce a rapid and powerful push-off during late stance are of importance for impaired gait function in children with CP. Intensive treadmill training may facilitate the drive to ankle plantar flexors and reduce gait asymmetry during both treadmill and overground walking.
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http://dx.doi.org/10.1016/j.humov.2019.102565DOI Listing
February 2020

Contribution of corticospinal drive to ankle plantar flexor muscle activation during gait in adults with cerebral palsy.

Exp Brain Res 2019 Jun 21;237(6):1457-1467. Epub 2019 Mar 21.

Institute of Neuroscience, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark.

Impaired plantar flexor muscle activation during push-off in late stance contributes importantly to reduced gait ability in adults with cerebral palsy (CP). Here we used low-intensity transcranial magnetic stimulation (TMS) to suppress soleus EMG activity during push-off as an estimate of corticospinal drive in CP adults and neurologically intact (NI) adults. Ten CP adults (age 34 years, SD 14.6, GMFCS I-II) and ten NI adults (age 33 years, SD 9.8) walked on a treadmill at their preferred walking speed. TMS of the leg motor cortex was elicited just prior to push-off during gait at intensities below threshold for motor-evoked potentials. Soleus EMG from steps with and without TMS were averaged and compared. Control experiments were performed while standing and in NI adults during gait at slow speed. TMS induced a suppression at a latency of about 40 ms. This suppression was similar in the two populations when differences in control EMG and gait speed were taken into account (CP 18%, NI 16%). The threshold of the suppression was higher in CP adults. The findings suggest that corticospinal drive to ankle plantar flexors at push-off is comparable in CP and NI adults. The higher threshold of the suppression in CP adults may reflect downregulation of cortical inhibition to facilitate corticospinal drive. Interventions aiming to facilitate excitability in cortical networks may contribute to maintain or even improve efficient gait in CP adults.
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http://dx.doi.org/10.1007/s00221-019-05520-3DOI Listing
June 2019

Corticospinal control of normal and visually guided gait in healthy older and younger adults.

Neurobiol Aging 2019 06 13;78:29-41. Epub 2019 Feb 13.

Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

We investigated age-related differences in corticospinal control of muscle activity during normal and visually guided (VG) walking. Young (n = 15, 22.1 ± 1.7 years) and older (n = 15, 68.3 ± 2.7 years) participants performed normal walking and VG walking requiring precise foot placement based on visual cues. Coherence analysis was used to quantify coupling between electroencephalography and electromyography from the anterior tibial muscle (corticomuscular) and between the 2 ends of the anterior tibial muscle (intramuscular) at 15-50 Hz during the swing phase of walking as markers of corticospinal activity. Our results indicated that corticomuscular and intramuscular coherence was lower in older compared to young participants during both tasks. In addition, coherence was generally greater during VG than during normal walking across age groups, although during late swing, older participants drove several of the observed task-related coherence increases. Performance on the VG task was lower in older compared to young participants and was correlated with task-related corticomuscular coherence modulations within the older group. These results suggest age-related differences in the corticospinal control of walking, with possible implications for precision control of foot placement based on visual information.
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http://dx.doi.org/10.1016/j.neurobiolaging.2019.02.005DOI Listing
June 2019

The development of functional and directed corticomuscular connectivity during tonic ankle muscle contraction across childhood and adolescence.

Neuroimage 2019 05 25;191:350-360. Epub 2019 Feb 25.

Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

In adults, oscillatory activity in the sensorimotor cortex is coherent with contralateral muscle activity at beta frequencies (15-35 Hz) during tonic contraction. This functional coupling reflects the involvement of the sensorimotor cortex, the corticospinal pathway, and likely also ascending sensory feedback in the task at hand. However, little is known about the developmental trajectory of task-related corticomuscular connectivity relating to the voluntary control of the ankle muscles. To address this, we recorded electroencephalography (EEG) from the vertex (Cz) and electromyography (EMG) from ankle muscles (proximal and distal anterior tibial, TA; soleus, SOL; gastrocnemius medialis, GM) in 33 participants aged 7-23 yr during tonic dorsi- and plantar flexion requiring precise maintenance of a submaximal torque level. Coherence was calculated for Cz-TA, Cz-SOL, TA-TA, and SOL-GM signal pairs. We found strong, positive associations between age and beta band coherence for Cz-TA, Cz-SOL, and TA-TA, suggesting that oscillatory corticomuscular connectivity is strengthened during childhood development and adolescence. Directionality analysis indicated that the primary interaction underlying this age-related increase was in the descending direction. In addition, performance during dorsi- and plantar flexion tasks was positively associated with age, indicating more precise control of the ankle joint in older participants. Performance was also positively associated with beta band coherence, suggesting that participants with greater coherence also exhibited greater precision. We propose that these results indicate an age-related increase in oscillatory corticospinal input to the ankle muscle motoneuron pools during childhood development and adolescence, with possible implications for maturation of precision force control. Within the theoretical framework of predictive coding, we suggest that our results may reflect an age-related increase in reliance on feedforward control as the developing nervous system becomes better at predicting the sensory consequences of movement. These findings may contribute to the development of novel intervention strategies targeting improved sensorimotor control in children and adolescents with central motor disorders.
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http://dx.doi.org/10.1016/j.neuroimage.2019.02.054DOI Listing
May 2019

Effects on Parental Stress of Early Home-Based CareToy Intervention in Low-Risk Preterm Infants.

Neural Plast 2019 22;2019:7517351. Epub 2019 Jan 22.

Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Calambrone, Pisa, Italy.

Parenting a preterm infant is more challenging than a full-term one. Parent involvement in early intervention programs seems to have positive psychosocial effects on both the child and parent. CareToy is an innovative smart system that provides an intensive individualized home-based family-centred EI in preterm infants between 3 and 9 age-corrected months. A RCT study, preceded by a pilot study, has been recently carried out to evaluate the effects of CareToy intervention on neurodevelopmental outcomes with respect to Standard Care. This study aims at evaluating the effects of CareToy early intervention on parenting stress in preterm infants. Parents (mother and father) of a subgroup of infants enrolled in the RCT filled out a self-report questionnaire on parenting stress (Parenting Stress Index-Short Form (PSI-SF)) before (T0) and after (T1) the CareToy or Standard Care period (4 weeks), according to the allocation of their preterm infant. For twins, an individual questionnaire for each one was filled out. Results obtained from mothers and fathers were separately analysed with nonparametric tests. 44 mothers and 44 fathers of 44 infants (24 CareToy/20 Standard Care) filled out the PSI-SF at T0 and at T1. CareToy intervention was mainly managed by mothers. A significant ( < 0.05) reduction in Parental Distress subscale in the CareToy group versus Standard Care was found in the mothers. No differences were found among the fathers. CareToy training seems to be effective in reducing parental distress in mothers, who spent more time on CareToy intervention. These findings confirm the importance of parental involvement in early intervention programs. This trial is registered with Clinical Trial.gov NCT01990183.
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http://dx.doi.org/10.1155/2019/7517351DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362470PMC
May 2019

Characterization of torque generating properties of ankle plantar flexor muscles in ambulant adults with cerebral palsy.

Eur J Appl Physiol 2019 May 18;119(5):1127-1136. Epub 2019 Feb 18.

Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark.

Purpose: Weakness of plantar flexor muscles is related to reduced push-off and forward propulsion during gait in persons with cerebral palsy (CP). It has not been clarified to what an extent altered muscle contractile properties contribute to this muscle weakness. Here, we investigated the torque generating capacity and muscle fascicle length in the triceps surae muscle throughout ankle range of motion (ROM) in adults with CP using maximal single muscle twitches elicited by electrical nerve stimulation and ultrasonography.

Methods: Fourteen adults with CP (age 36, SD 10.6, GMFCS I-III) and 17 neurological intact (NI) adults (age 36, SD 4.5) participated. Plantar flexor torque during supramaximal stimulation of the tibial nerve was recorded in a dynamometer at 8 ankle angles throughout ROM. Medial gastrocnemius (MG) fascicle length was tracked using ultrasonography.

Results: Adults with CP showed reduced plantar flexor torque and fascicle shortening during supramaximal stimulation throughout ROM. The largest torque generation was observed at the ankle joint position where the largest shortening of MG fascicles was observed in both groups. This was at a more plantarflexed position in the CP group.

Conclusion: Reduced torque and fascicle shortening during supramaximal stimulation of the tibial nerve indicate impaired contractile properties of plantar flexor muscles in adults with CP. Maximal torque was observed at a more plantarflexed position in adults with CP indicating an altered torque-fascicle length/ankle angle relation. The findings suggest that gait rehabilitation in adults with CP may require special focus on improvement of muscle contractility.
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http://dx.doi.org/10.1007/s00421-019-04102-zDOI Listing
May 2019

Are sensorimotor experiences the key for successful early intervention in infants with congenital brain lesion?

Infant Behav Dev 2019 02 12;54:133-139. Epub 2019 Feb 12.

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark; DTU Compute, Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kgs. Lyngby, Denmark.

Living with a congenital brain lesion may have detrimental effects on the ability to do everyday activities, but contrary to acquired brain lesions, people and in particular children, with congenital brain lesions may have limited or no experience of how their bodies work. This absence of experience gives rise to challenges for habilitation of sensorimotor abilities and derived cognitive abilities. How can motor and cognitive abilities be achieved and trained in an individual with no experience of potential abilities? In this article, we aim to review the existing knowledge about the development of sensorimotor integration. Further, we will discuss this knowledge in the light of two neurocognitive theories: embodied cognition and predictive coding. Moreover, using developmental knowledge and theory in combination, we will argue that early sensorimotor development serves as a foundation for later cognitive development. Finally, we try to use these elements in a strategy to make interventions as early as possible, with the purpose of improving sensorimotor and cognitive abilities in children with congenital brain lesions.
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http://dx.doi.org/10.1016/j.infbeh.2019.02.001DOI Listing
February 2019

Maturation of feedforward toe walking motor program is impaired in children with cerebral palsy.

Brain 2019 03;142(3):526-541

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

Voluntary toe walking in adults is characterized by feedforward control of ankle muscles in order to ensure optimal stability of the ankle joint at ground impact. Toe walking is frequently observed in children with cerebral palsy, but the mechanisms involved have not been clarified. Here, we investigated maturation of voluntary toe walking in typically-developing children and typically-developed adults and compared it to involuntary toe walking in children with cerebral palsy. Twenty-eight children with cerebral palsy (age 3-14 years), 24 typically-developing children (age 2-14 years) and 15 adults (mean age 30.7 years) participated in the study. EMG activity was measured from the tibialis anterior and soleus muscles together with knee and ankle joint position during treadmill walking. In typically-developed adults, low step-to-step variability of the drop of the heel after ground impact was correlated with low tibialis anterior and high soleus EMG with no significant coupling between the antagonist muscle EMGs. Typically-developing children showed a significant age-related decline in EMG amplitude reaching an adult level at 10-12 years of age. The youngest typically-developing children showed a broad peak EMG-EMG synchronization (>100 ms) associated with large 5-15 Hz coherence between antagonist muscle activities. EMG coherence declined with age and at the age of 10-12 years no correlation was observed similar to adults. This reduction in coherence was closely related to improved step-to-step stability of the ankle joint position. Children with cerebral palsy generally showed lower EMG levels than typically-developing children and larger step-to-step variability in ankle joint position. In contrast to typically-developing children, children with cerebral palsy showed no age-related decline in tibialis anterior EMG amplitude. Motor unit synchronization and 5-15 Hz coherence between antagonist EMGs was observed more frequently in children with cerebral palsy when compared to typically-developing children and in contrast to typically-developing participants there was no age-related decline. We conclude that typically-developing children develop mature feedforward control of ankle muscle activity as they age, such that at age 10-12 years there is little agonist-antagonist muscle co-contraction around the time of foot-ground contact during toe walking. Children with cerebral palsy, in contrast, continue to co-contract agonist and antagonist ankle muscles when toe walking. We speculate that children with cerebral palsy maintain a co-contraction activation pattern when toe walking due to weak muscles and insufficient motor and sensory signalling necessary for optimization of feedforward motor programs. These findings are important for understanding of the pathophysiology and treatment of toe walking.
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http://dx.doi.org/10.1093/brain/awz002DOI Listing
March 2019

Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait.

J Mot Behav 2019 18;51(6):668-680. Epub 2019 Jan 18.

Elsass Institute , Charlottenlund, Denmark .

The present study used coherence and directionality analyses to explore whether the motor cortex contributes to plantar flexor muscle activity during the stance phase and push-off phase during gait. Subjects walked on a treadmill, while EEG over the leg motorcortex area and EMG from the medial gastrocnemius and soleus muscles was recorded. Corticomuscular and intermuscular coherence were calculated from pair-wise recordings. Significant EEG-EMG and EMG-EMG coherence in the beta and gamma frequency bands was found throughout the stance phase with the largest coherence towards push-off. Analysis of directionality revealed that EEG activity preceded EMG activity throughout the stance phase until the time of push-off. These findings suggest that the motor cortex contributes to ankle plantar flexor muscle activity and forward propulsion during gait.
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http://dx.doi.org/10.1080/00222895.2018.1563762DOI Listing
May 2020

The neurophysiology of deforming spastic paresis: A revised taxonomy.

Ann Phys Rehabil Med 2019 Nov 28;62(6):426-430. Epub 2018 Nov 28.

Service de rééducation neurolocomotrice, EA 7377 BIOTN, laboratoire analyse et restauration du mouvement, université Paris-Est Créteil, hôpitaux universitaires Henri-Mondor, Assistance publique-Hôpitaux de Paris, 51, avenue du Maréchal-de-Lattre-de-Tassigny, 94010 Créteil, France.

This paper revisits the taxonomy of the neurophysiological consequences of a persistent impairment of motor command execution in the classic environment of sensorimotor restriction and muscle hypo-mobilization in short position. Around each joint, the syndrome involves 2 disorders, muscular and neurologic. The muscular disorder is promoted by muscle hypo-mobilization in short position in the context of paresis, in the hours and days after paresis onset: this genetically mediated, evolving myopathy, is called spastic myopathy. The clinician may suspect it by feeling extensibility loss in a resting muscle, although long after the actual onset of the disease. The neurologic disorder, promoted by sensorimotor restriction in the context of paresis and by the muscle disorder itself, comprises 4 main components, mostly affecting antagonists to desired movements: the first is spastic dystonia, an unwanted, involuntary muscle activation at rest, in the absence of stretch or voluntary effort; spastic dystonia superimposes on spastic myopathy to cause visible, gradually increasing body deformities; the second is spastic cocontraction, an unwanted, involuntary antagonist muscle activation during voluntary effort directed to the agonist, aggravated by antagonist stretch; it is primarily due to misdirection of the supraspinal descending drive and contributes to reducing movement amplitude; and the third is spasticity, one form of hyperreflexia, defined by an enhancement of the velocity-dependent responses to phasic stretch, detected and measured at rest (another form of hyperreflexia is "nociceptive spasms", following flexor reflex afferent stimulation, particularly after spinal cord lesions). The 3 main forms of overactivity, spastic dystonia, spastic cocontraction and spasticity, share the same motor neuron hyperexcitability as a contributing factor, all being predominant in the muscles that are more affected by spastic myopathy. The fourth component of the neurologic disorder affects the agonist: it is stretch-sensitive paresis, which is a decreased access of the central command to the agonist, aggravated by antagonist stretch. Improved understanding of the pathophysiology of deforming spastic paresis should help clinicians select meaningful assessments and refined treatments, including the utmost need to preserve muscle tissue integrity as soon as paresis sets in.
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http://dx.doi.org/10.1016/j.rehab.2018.10.004DOI Listing
November 2019

Sequence variants in muscle tissue-related genes may determine the severity of muscle contractures in cerebral palsy.

Am J Med Genet B Neuropsychiatr Genet 2019 01 23;180(1):12-24. Epub 2018 Nov 23.

Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

Muscle contractures are a common complication to cerebral palsy (CP). The purpose of this study was to evaluate whether individuals with CP carry specific gene variants of important structural genes that might explain the severity of muscle contractures. Next-generation-sequencing (NGS) of 96 candidate genes associated with muscle structure and metabolism were analyzed in 43 individuals with CP (Gross Motor Function classification system [GMFCS] I, n=10; GMFCS II, n=14; GMFCS III, n=19) and four control participants. In silico analysis of the identified variants was performed. The variants were classified into four categories ranging from likely benign (VUS0) to highly likely functional effect (VUS3). All individuals with CP were classified and grouped according to their GMFCS level: Statistical comparisons were made between GMFCS groups. Kruskal-Wallis tests showed significantly more VUS2 variants in the genes COL4 (GMFCS I-III; 1, 1, 5, respectively [p < .04]), COL5 (GMFCS I-III; 1, 1, 5 [p < .04]), COL6 (GMFCS I-III; 0, 4, 7 [p < .003]), and COL9 (GMFCS I-III; 1, 1, 5 [p < .04]), in individuals with CP within GMFCS Level III when compared to the other GMFCS levels. Furthermore, significantly more VUS3 variants in COL6 (GMFCS I-III; 0, 5, 2 [p < .01]) and COL7 (GMFCS I-III; 0, 3, 0 [p < .04]) were identified in the GMFCS II level when compared to the other GMFCS levels. The present results highlight several candidate gene variants in different collagen types with likely functional effects in individuals with CP.
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http://dx.doi.org/10.1002/ajmg.b.32693DOI Listing
January 2019

Impaired Ability to Suppress Excitability of Antagonist Motoneurons at Onset of Dorsiflexion in Adults with Cerebral Palsy.

Neural Plast 2018 9;2018:1265143. Epub 2018 Oct 9.

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

We recently showed that impaired gait function in adults with cerebral palsy (CP) is associated with reduced rate of force development in ankle dorsiflexors. Here, we explore potential mechanisms. We investigated the suppression of antagonist excitability, calculated as the amount of soleus H-reflex depression at the onset of ankle dorsiflexion compared to rest, in 24 adults with CP (34.3 years, range 18-57; GMFCS 1.95, range 1-3) and 15 healthy, age-matched controls. Furthermore, the central common drive to dorsiflexor motoneurons during a static contraction in the two groups was examined by coherence analyses. The H-reflex was significantly reduced by 37% at the onset of dorsiflexion compared to rest in healthy adults ( < 0.001) but unchanged in adults with CP ( = 0.91). Also, the adults with CP had significantly less coherence. These findings suggest that the ability to suppress antagonist motoneuronal excitability at movement onset is impaired and that the central common drive during static contractions is reduced in adults with CP.
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http://dx.doi.org/10.1155/2018/1265143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6198563PMC
January 2019

Oscillatory Corticospinal Activity during Static Contraction of Ankle Muscles Is Reduced in Healthy Old versus Young Adults.

Neural Plast 2018 26;2018:3432649. Epub 2018 Apr 26.

Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.

Aging is accompanied by impaired motor function, but age-related changes in neural networks responsible for generating movement are not well understood. We aimed to investigate the functional oscillatory coupling between activity in the sensorimotor cortex and ankle muscles during static contraction. Fifteen young (20-26 yr) and fifteen older (65-73 yr) subjects were instructed to match a target force by performing static ankle dorsi- or plantar flexion, while electroencephalographic (EEG) activity was recorded from the cortex and electromyographic (EMG) activity was recorded from dorsi- (proximal and distal anterior tibia) and plantar (soleus and medial gastrocnemius) flexor muscles. EEG-EMG and EMG-EMG beta band (15-35 Hz) coherence was analyzed as an index of corticospinal activity. Our results demonstrated that beta cortico-, intra-, and intermuscular coherence was reduced in old versus young subjects during static contractions. Old subjects demonstrated significantly greater error than young subjects while matching target forces, but force precision was not related to beta coherence. We interpret this as an age-related decrease in effective oscillatory corticospinal activity during steady-state motor output. Additionally, our data indicate a potential effect of alpha coherence and tremor on performance. These results may be instrumental in developing new interventions to strengthen sensorimotor control in elderly subjects.
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http://dx.doi.org/10.1155/2018/3432649DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5944232PMC
December 2018

Microvascularization is not a limiting factor for exercise in adults with cerebral palsy.

J Appl Physiol (1985) 2018 08 3;125(2):536-544. Epub 2018 May 3.

Center for Neuroscience, Copenhagen University , Copenhagen , Denmark.

Muscle contractures are a common complication in patients with central nervous system (CNS) lesions which limit range of movement and cause joint deformities. Furthermore, it has previously been shown that muscles with contractures have a reduced number of capillaries, indicating decreased tissue vascularization. The aim of the present study was to investigate the microvascular volume (MV) at rest and after acute exercise in the muscle tissue of individuals with cerebral palsy (CP) and healthy control individuals. Contrast-enhanced ultrasound (CEUS) was used before and after 30 min of walking or running on a treadmill in 10 healthy control participants and 10 individuals with CP to detect MV of their skeletal muscle tissue. A significant increase in the MV was observed after exercise both in the adult CP group (21-53 yr) and in the control group (21-52 yr) (1.8 ± 0.8 ΔdB to 3.1 ± 0.9 ΔdB or 42.9% and 1.5 ± 0.6 ΔdB to 2.5 ± 0.9 ΔdB or 39.0%, respectively). Furthermore, a difference in the resting MV was observed between the most severe cases of CP [gross motor function classification scale (GMFCS) 3 and 4] (2.3 ± 0.5 ΔdB) and the less severe cases (GMFCS 1 and 2) (1.5 ± 0.2 ΔdB). When the CP group was walking (3.4 km/h), the lactate levels, Borg score, and heart rate matched the level of controls when they were running (9.8 km/h). In conclusion, individuals with CP become exhausted at much lower exercise intensities than healthy individuals. This is not explained by impaired microvascularization, since the MV of the individuals with CP respond normally to increased O demand during acute exercise. NEW & NOTEWORTHY Cerebral palsy (CP) patients were less physically active compared with typically developed individuals. This may affect the microvascularization. We observed that the CP group became exhausted at much lower exercise intensities compared with healthy individuals. However, impaired microvascularization was not the reason for the decreased physical activity as the CP group responded normally to increased O demand during acute exercise. These results indicate that walking may be recommended as an intervention to train and maintain skeletal muscle tissue in individuals with CP.
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http://dx.doi.org/10.1152/japplphysiol.00827.2017DOI Listing
August 2018
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