SMN is required for sensory-motor circuit function in Drosophila

PubMed Central

Imlach, Wendy L.; Beck, Erin S.; Choi, Ben Jiwon; Lotti, Francesco; Pellizzoni, Livio; McCabe, Brian D.

2012-01-01

Summary Spinal muscular atrophy (SMA) is a lethal human disease characterized by motor neuron dysfunction and muscle deterioration due to depletion of the ubiquitous Survival Motor Neuron (SMN) protein. Drosophila SMN mutants have reduced muscle size and defective locomotion, motor rhythm and motor neuron neurotransmission. Unexpectedly, restoration of SMN in either muscles or motor neurons did not alter these phenotypes. Instead, SMN must be expressed in proprioceptive neurons and interneurons in the motor circuit to non-autonomously correct defects in motor neurons and muscles. SMN depletion disrupts the motor system subsequent to circuit development and can be mimicked by the inhibition of motor network function. Furthermore, increasing motor circuit excitability by genetic or pharmacological inhibition of K+ channels can correct SMN-dependent phenotypes. These results establish sensory-motor circuit dysfunction as the origin of motor system deficits in this SMA model and suggest that enhancement of motor neural network activity could ameliorate the disease. PMID:23063130

Analysis of motor dysfunction in Down Syndrome reveals motor neuron degeneration

PubMed Central

Lana-Elola, Eva; Gibbins, Dorota; La Russa, Federica; Wiseman, Frances; Williamson, Matthew; Saccon, Rachele; Olerinyova, Anna; Mahmood, Radma; Nye, Emma; Cater, Heather; Yu, Y. Eugene; Bennett, David L. H.; Greensmith, Linda; Fisher, Elizabeth M. C.

2018-01-01

Down Syndrome (DS) is caused by trisomy of chromosome 21 (Hsa21) and results in a spectrum of phenotypes including learning and memory deficits, and motor dysfunction. It has been hypothesized that an additional copy of a few Hsa21 dosage-sensitive genes causes these phenotypes, but this has been challenged by observations that aneuploidy can cause phenotypes by the mass action of large numbers of genes, with undetectable contributions from individual sequences. The motor abnormalities in DS are relatively understudied—the identity of causative dosage-sensitive genes and the mechanism underpinning the phenotypes are unknown. Using a panel of mouse strains with duplications of regions of mouse chromosomes orthologous to Hsa21 we show that increased dosage of small numbers of genes causes locomotor dysfunction and, moreover, that the Dyrk1a gene is required in three copies to cause the phenotype. Furthermore, we show for the first time a new DS phenotype: loss of motor neurons both in mouse models and, importantly, in humans with DS, that may contribute to locomotor dysfunction. PMID:29746474

At the interface of sensory and motor dysfunctions and Alzheimer's disease.

PubMed

Albers, Mark W; Gilmore, Grover C; Kaye, Jeffrey; Murphy, Claire; Wingfield, Arthur; Bennett, David A; Boxer, Adam L; Buchman, Aron S; Cruickshanks, Karen J; Devanand, Davangere P; Duffy, Charles J; Gall, Christine M; Gates, George A; Granholm, Ann-Charlotte; Hensch, Takao; Holtzer, Roee; Hyman, Bradley T; Lin, Frank R; McKee, Ann C; Morris, John C; Petersen, Ronald C; Silbert, Lisa C; Struble, Robert G; Trojanowski, John Q; Verghese, Joe; Wilson, Donald A; Xu, Shunbin; Zhang, Li I

2015-01-01

Recent evidence indicates that sensory and motor changes may precede the cognitive symptoms of Alzheimer's disease (AD) by several years and may signify increased risk of developing AD. Traditionally, sensory and motor dysfunctions in aging and AD have been studied separately. To ascertain the evidence supporting the relationship between age-related changes in sensory and motor systems and the development of AD and to facilitate communication between several disciplines, the National Institute on Aging held an exploratory workshop titled "Sensory and Motor Dysfunctions in Aging and AD." The scientific sessions of the workshop focused on age-related and neuropathologic changes in the olfactory, visual, auditory, and motor systems, followed by extensive discussion and hypothesis generation related to the possible links among sensory, cognitive, and motor domains in aging and AD. Based on the data presented and discussed at this workshop, it is clear that sensory and motor regions of the central nervous system are affected by AD pathology and that interventions targeting amelioration of sensory-motor deficits in AD may enhance patient function as AD progresses. Copyright © 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Oral methylphenidate alleviates the fine motor dysfunction caused by chronic postnatal manganese exposure in adult rats.

PubMed

Beaudin, Stéphane A; Strupp, Barbara J; Lasley, Stephen M; Fornal, Casimir A; Mandal, Shyamali; Smith, Donald R

2015-04-01

Developmental manganese (Mn) exposure is associated with motor dysfunction in children and animal models, but little is known about the underlying neurochemical mechanisms or the potential for amelioration by pharmacotherapy. We investigated whether methylphenidate (MPH) alleviates fine motor dysfunction due to chronic postnatal Mn exposure, and whether Mn exposure impairs brain extracellular dopamine (DA) and norepinephrine (NE) in the prefrontal cortex (PFC) and striatum in adult animals. Rats were orally exposed to 0 or 50 mg Mn/kg/day from postnatal day 1 until the end of the study (PND 145). The staircase test was used to assess skilled forelimb function. Oral MPH (2.5 mg/kg/day) was administered daily 1 h before staircase testing for 16 days. DA and NE levels were measured by dual probe microdialysis. Results show that Mn exposure impaired reaching and grasping skills and the evoked release of DA and NE in the PFC and striatum of adult rats. Importantly, oral MPH treatment fully alleviated the fine motor deficits in the Mn-exposed animals, but did not affect forelimb skills of control rats not exposed to Mn. These results suggest that catecholaminergic hypofunctioning in the PFC and striatum may underlie the Mn-induced fine motor dysfunction, and that oral MPH pharmacotherapy is an effective treatment approach for alleviating this dysfunction in adult animals. The therapeutic potential of MPH for the treatment of motor dysfunction in Mn-exposed children and adults appears promising pending further characterization of MPH efficacy in other functional areas (eg, attention) believed to be affected by developmental Mn exposure. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Hypopituitarism after acute brain injury.

PubMed

Urban, Randall J

2006-07-01

Acute brain injury has many causes, but the most common is trauma. There are 1.5-2.0 million traumatic brain injuries (TBI) in the United States yearly, with an associated cost exceeding 10 billion dollars. TBI is the most common cause of death and disability in young adults less than 35 years of age. The consequences of TBI can be severe, including disability in motor function, speech, cognition, and psychosocial and emotional skills. Recently, clinical studies have documented the occurrence of pituitary dysfunction after TBI and another cause of acute brain injury, subarachnoid hemorrhage (SAH). These studies have consistently demonstrated a 30-40% occurrence of pituitary dysfunction involving at least one anterior pituitary hormone following a moderate to severe TBI or SAH. Growth hormone (GH) deficiency is the most common pituitary hormone disorder, occurring in approximately 20% of patients when multiple tests of GH deficiency are used. Within 7-21 days of acute brain injury, adrenal insufficiency is the primary concern. Pituitary function can fluctuate over the first year after TBI, but it is well established by 1 year. Studies are ongoing to assess the effects of hormone replacement on motor function and cognition in TBI patients. Any subject with a moderate to severe acute brain injury should be screened for pituitary dysfunction.

[Oral motor dysfunction, feeding problems and nutritional status in children with cerebral palsy].

PubMed

Hou, Mei; Fu, Ping; Zhao, Jian-hui; Lan, Kun; Zhang, Hong

2004-10-01

This study was undertaken to investigate the clinical features of oral motor dysfunction and feeding problems as well as the nutritional status of children with cerebral palsy (CP). Fifty-nine CP children, 39 boys and 20 girls, mean age 31 months (20 to 72 months), were recruited. Their parents were interviewed for high risk factors and feeding history. Each case was assessed for oral motor and feeding problems based on oral motor and feeding skill score; for nutritional status by measurement of weight, height; neurologically for type of cerebral palsy and for developmental age by Gesell's developmental scale. Equal number of age and sex matched controls were included for comparison of nutritional status, oral motor and feeding skill score. Among 59 patients, 51 cases had oral motor dysfunction and 55 cases had feeding problems including all athtosis, spastic tetraplegia, and 16 had spastic diplegia. The scores of both the mean oral motor function and feeding skill of CP children were significantly lower than those of the controls (P < 0.001). Main food of children with cerebral palsy consisted of liquid and semisolid diet. Body weight and height below the 25th percentile were found in 13 cases and 19 cases, respectively. The majority of the children with cerebral palsy had oral motor dysfunction and feeding problems which appeared in early age and disturbed the growth and nutritional status. Thorough assessment for oral motor function, feeding problems and nutritional status of CP children is indicated in order to start timely rehabilitation and nutritional interventions which can significantly improve their nutritional status and quality of life.

Survival motor neuron protein in motor neurons determines synaptic integrity in spinal muscular atrophy.

PubMed

Martinez, Tara L; Kong, Lingling; Wang, Xueyong; Osborne, Melissa A; Crowder, Melissa E; Van Meerbeke, James P; Xu, Xixi; Davis, Crystal; Wooley, Joe; Goldhamer, David J; Lutz, Cathleen M; Rich, Mark M; Sumner, Charlotte J

2012-06-20

The inherited motor neuron disease spinal muscular atrophy (SMA) is caused by deficient expression of survival motor neuron (SMN) protein and results in severe muscle weakness. In SMA mice, synaptic dysfunction of both neuromuscular junctions (NMJs) and central sensorimotor synapses precedes motor neuron cell death. To address whether this synaptic dysfunction is due to SMN deficiency in motor neurons, muscle, or both, we generated three lines of conditional SMA mice with tissue-specific increases in SMN expression. All three lines of mice showed increased survival, weights, and improved motor behavior. While increased SMN expression in motor neurons prevented synaptic dysfunction at the NMJ and restored motor neuron somal synapses, increased SMN expression in muscle did not affect synaptic function although it did improve myofiber size. Together these data indicate that both peripheral and central synaptic integrity are dependent on motor neurons in SMA, but SMN may have variable roles in the maintenance of these different synapses. At the NMJ, it functions at the presynaptic terminal in a cell-autonomous fashion, but may be necessary for retrograde trophic signaling to presynaptic inputs onto motor neurons. Importantly, SMN also appears to function in muscle growth and/or maintenance independent of motor neurons. Our data suggest that SMN plays distinct roles in muscle, NMJs, and motor neuron somal synapses and that restored function of SMN at all three sites will be necessary for full recovery of muscle power.

BEHAVIORAL AND LEARNING DISABILITIES ASSOCIATED WITH COGNITIVE-MOTOR DYSFUNCTION. INTERIM REPORT.

ERIC Educational Resources Information Center

BRAUN, JEAN S.; RUBIN, ELI Z.

THIS REPORT EXAMINES THE RELATIONSHIP BETWEEN BEHAVIORAL AND ACADEMIC DISABILITIES AND COGNITIVE-MOTOR DYSFUNCTION AS REVEALED BY DATA ON 400 ELEMENTARY SCHOOL CHILDREN. THE BEHAVIOR CHECKLIST WAS USED AS A BASIS FOR SAMPLE SELECTION. BEHAVIOR CLUSTERS REFLECTING BOTH ANTI-SOCIAL TENDENCIES AND UNASSERTIVE, WITHDRAWN BEHAVIOR WERE IDENTIFIED. A…

Neural correlates underlying micrographia in Parkinson’s disease

PubMed Central

Zhang, Jiarong; Hallett, Mark; Feng, Tao; Hou, Yanan; Chan, Piu

2016-01-01

Micrographia is a common symptom in Parkinson’s disease, which manifests as either a consistent or progressive reduction in the size of handwriting or both. Neural correlates underlying micrographia remain unclear. We used functional magnetic resonance imaging to investigate micrographia-related neural activity and connectivity modulations. In addition, the effect of attention and dopaminergic administration on micrographia was examined. We found that consistent micrographia was associated with decreased activity and connectivity in the basal ganglia motor circuit; while progressive micrographia was related to the dysfunction of basal ganglia motor circuit together with disconnections between the rostral supplementary motor area, rostral cingulate motor area and cerebellum. Attention significantly improved both consistent and progressive micrographia, accompanied by recruitment of anterior putamen and dorsolateral prefrontal cortex. Levodopa improved consistent micrographia accompanied by increased activity and connectivity in the basal ganglia motor circuit, but had no effect on progressive micrographia. Our findings suggest that consistent micrographia is related to dysfunction of the basal ganglia motor circuit; while dysfunction of the basal ganglia motor circuit and disconnection between the rostral supplementary motor area, rostral cingulate motor area and cerebellum likely contributes to progressive micrographia. Attention improves both types of micrographia by recruiting additional brain networks. Levodopa improves consistent micrographia by restoring the function of the basal ganglia motor circuit, but does not improve progressive micrographia, probably because of failure to repair the disconnected networks. PMID:26525918

Children with intellectual disability and hospice utilization

PubMed Central

Lindley, Lisa C.; Colman, Mari Beth; Meadows, John T.

2016-01-01

Over 42,000 children die each year in the United States, including those with intellectual disability (ID). Survival is often reduced when children with intellectual disability also suffer from significant motor dysfunction, progressive congenital conditions, and comorbidities. Yet, little is known about hospice care for children with intellectual disability. The purpose of this study was to explore the relationship between intellectual disability and hospice utilization. Additionally, we explored whether intellectual disability combined with motor dysfunction, progressive congenital conditions, and comorbidities influenced pediatric hospice utilization. Using a retrospective cohort design and data from the 2009 to 2010 California Medicaid claims files, we conducted a multivariate analysis of hospice utilization. This study shows that intellectual disability was negatively related to hospice enrollment and length of stay. We also found that when children had both intellectual disability and comorbidities, there was a positive association with enrolling in hospice care. A number of clinical implications can be drawn from the study findings that hospice and palliative care nurses use to improve their clinical practice of caring for children with ID and their families at end of life. PMID:28260997

Children with intellectual disability and hospice utilization.

PubMed

Lindley, Lisa C; Colman, Mari Beth; Meadows, John T

2017-02-01

Over 42,000 children die each year in the United States, including those with intellectual disability (ID). Survival is often reduced when children with intellectual disability also suffer from significant motor dysfunction, progressive congenital conditions, and comorbidities. Yet, little is known about hospice care for children with intellectual disability. The purpose of this study was to explore the relationship between intellectual disability and hospice utilization. Additionally, we explored whether intellectual disability combined with motor dysfunction, progressive congenital conditions, and comorbidities influenced pediatric hospice utilization. Using a retrospective cohort design and data from the 2009 to 2010 California Medicaid claims files, we conducted a multivariate analysis of hospice utilization. This study shows that intellectual disability was negatively related to hospice enrollment and length of stay. We also found that when children had both intellectual disability and comorbidities, there was a positive association with enrolling in hospice care. A number of clinical implications can be drawn from the study findings that hospice and palliative care nurses use to improve their clinical practice of caring for children with ID and their families at end of life.

Obesity Reduces Cognitive and Motor Functions across the Lifespan

PubMed Central

Wang, Chuanming; Chan, John S. Y.; Ren, Lijie; Yan, Jin H.

2016-01-01

Due to a sedentary lifestyle, more and more people are becoming obese nowadays. In addition to health-related problems, obesity can also impair cognition and motor performance. Previous results have shown that obesity mainly affects cognition and motor behaviors through altering brain functions and musculoskeletal system, respectively. Many factors, such as insulin/leptin dysregulation and inflammation, mediate the effect of obesity and cognition and motor behaviors. Substantial evidence has suggested exercise to be an effective way to improve obesity and related cognitive and motor dysfunctions. This paper aims to discuss the association of obesity with cognition and motor behaviors and its underlying mechanisms. Following this, mechanisms of exercise to improve obesity-related dysfunctions are described. Finally, implications and future research direction are raised. PMID:26881095

Obesity Reduces Cognitive and Motor Functions across the Lifespan.

PubMed

Wang, Chuanming; Chan, John S Y; Ren, Lijie; Yan, Jin H

2016-01-01

Due to a sedentary lifestyle, more and more people are becoming obese nowadays. In addition to health-related problems, obesity can also impair cognition and motor performance. Previous results have shown that obesity mainly affects cognition and motor behaviors through altering brain functions and musculoskeletal system, respectively. Many factors, such as insulin/leptin dysregulation and inflammation, mediate the effect of obesity and cognition and motor behaviors. Substantial evidence has suggested exercise to be an effective way to improve obesity and related cognitive and motor dysfunctions. This paper aims to discuss the association of obesity with cognition and motor behaviors and its underlying mechanisms. Following this, mechanisms of exercise to improve obesity-related dysfunctions are described. Finally, implications and future research direction are raised.

[Hand motor dysfunctions in computer users].

PubMed

Shavlovskaia, O A; Shvarkov, S B; Posokhov, S I

2010-01-01

It were studied 239 female typists aged from 16 to 62 years (mean age 20,1±7,8 years) using author's questionnaire for computer typists to assess hand function and develop preventive measures of disturbances revealed. Indirect signs of tunnel hand neuropathy (27,2%), focal hand dystonia (21,4%) and muscular-tonic syndromes of different localization (18%) have been found. Typists are a risk group of fine hand motor dysfunctions. As preventive measures, authors recommend to use computer auxiliary devices, to change a motor stereotype during the day, to make hand "motor holidays", to organize working place.

Intraoperative diffusion tensor imaging predicts the recovery of motor dysfunction after insular lesions☆

PubMed Central

Li, Jinjiang; Chen, Xiaolei; Zhang, Jiashu; Zheng, Gang; Lv, Xueming; Li, Fangye; Hu, Shen; Zhang, Ting; Xu, Bainan

2013-01-01

Insular lesions remain surgically challenging because of the need to balance aggressive resection and functional protection. Motor function deficits due to corticospinal tract injury are a common complication of surgery for lesions adjacent to the internal capsule and it is therefore essential to evaluate the corticospinal tract adjacent to the lesion. We used diffusion tensor imaging to evaluate the corticospinal tract in 89 patients with insular lobe lesions who underwent surgery in Chinese PLA General Hospital from February 2009 to May 2011. Postoperative motor function evaluation revealed that 57 patients had no changes in motor function, and 32 patients suffered motor dysfunction or aggravated motor dysfunction. Of the affected patients, 20 recovered motor function during the 6–12-month follow-up, and an additional 12 patients did not recover over more than 12 months of follow-up. Following reconstruction of the corticospinal tract, fractional anisotropy comparison demonstrated that preoperative, intraoperative and follow-up normalized fractional anisotropy in the stable group was higher than in the transient deficits group or the long-term deficits group. Compared with the transient deficits group, intraoperative normalized fractional anisotropy significantly decreased in the long-term deficits group. We conclude that intraoperative fractional anisotropy values of the corticospinal tracts can be used as a prognostic indicator of motor function outcome. PMID:25206435

On the use of information theory for detecting upper limb motor dysfunction: An application to Parkinson’s disease

NASA Astrophysics Data System (ADS)

de Oliveira, M. Elias; Menegaldo, L. L.; Lucarelli, P.; Andrade, B. L. B.; Büchler, P.

2011-11-01

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra, decreased striatal dopamine levels, and consequent extrapyramidal motor dysfunctions. Several potential early diagnostic markers of PD have been proposed. Since they have not been validated in presymptomatic PD, the diagnosis and monitoring of the disease is based on subjective clinical assessment of cognitive and motor symptoms. In this study, we investigated interjoint coordination synergies in the upper limb of healthy and parkinsonian subjects during the performance of unconstrained linear-periodic movements in a horizontal plane using the mutual information (MI). We found that the MI is a sensitive metric in detecting upper limb motor dysfunction, thus suggesting that this method might be applicable to quantitatively evaluating the effects of the antiparkinsonian medication and to monitor the disease progression.

A SMN-Dependent U12 Splicing Event Essential for Motor Circuit Function

PubMed Central

Lotti, Francesco; Imlach, Wendy L.; Saieva, Luciano; Beck, Erin S.; Hao, Le T.; Li, Darrick K.; Jiao, Wei; Mentis, George Z.; Beattie, Christine E.; McCabe, Brian D.; Pellizzoni, Livio

2012-01-01

SUMMARY Spinal muscular atrophy (SMA) is a motor neuron disease caused by deficiency of the ubiquitous survival motor neuron (SMN) protein. To define the mechanisms of selective neuronal dysfunction in SMA, we investigated the role of SMN-dependent U12 splicing events in the regulation of motor circuit activity. We show that SMN deficiency perturbs splicing and decreases the expression of a subset of U12 intron-containing genes in mammalian cells and Drosophila larvae. Analysis of these SMN target genes identifies Stasimon as a novel protein required for motor circuit function. Restoration of Stasimon expression in the motor circuit corrects defects in neuromuscular junction transmission and muscle growth in Drosophila SMN mutants and aberrant motor neuron development in SMN-deficient zebrafish. These findings directly link defective splicing of critical neuronal genes induced by SMN deficiency to motor circuit dysfunction, establishing a molecular framework for the selective pathology of SMA. PMID:23063131

Selected Articles on Feeding Children Who Have a Neuromuscular Disorder. TIES: Therapy in Educational Settings.

ERIC Educational Resources Information Center

Hall, Sandra; And Others

The manual contains articles about evaluating and addressing the feeding needs of children who have oral-motor dysfunctions. "Helpful Hints for Feeding Children with Oral-Motor Dysfunction" (Janet Wilson) offers 20 suggestions relating to such areas as positioning the child, monitoring food preferences, and attending to oral hygiene.…

Oral administration of metal chelator ameliorates motor dysfunction after a small hemorrhage near the internal capsule in rat.

PubMed

Masuda, Tadashi; Hida, Hideki; Kanda, Yoshie; Aihara, Noritaka; Ohta, Kengo; Yamada, Kazuo; Nishino, Hitoo

2007-01-01

Cerebral hemorrhage leads to local production of free iron, radicals, cytokines, etc. To investigate whether a decrease of iron-mediated radical production influences functional recovery after intracerebral hemorrhage (ICH), a modified ICH rat model with a small hemorrhage near the internal capsule (IC) accompanied with relatively severe motor dysfunction was first developed. Then clioquinol (CQ), an iron chelator that reduces hydroxyl radical production, was orally administrated. Injection of different doses of Type IV collagenase (1.4 mul 1-200 U/ml) into the left striatum near the IC in Wistar rats showed that injection of 7.5 U/ml collagenase resulted in a small hemorrhoidal lesion near the IC with relatively severe motor dysfunction (IC model). Retrograde labeling of neurons in the sensory-motor cortex and axons in the corticospinal tract using Fluoro-gold (FG) injection into the spinal cord (C3-C4) showed that few labeled neurons in the sensory-motor cortex were detected in the IC model, FG-labeled axons disappeared, and FG-including ED-1-positive cells appeared within 24 hr in the IC. Assessments of behavior and histologic analysis after oral administration of CQ in the IC model indicated that oral administration of CQ prevented a decrease of FG-labeled neurons, and resulted in better motor-function recovery. CQ inhibited hydrogen peroxide-induced cell toxicity in oligodendrocytes in vitro, but not in neurons. Our data suggests that CQ ameliorated motor dysfunction after a small hemorrhage near the IC by a mechanism that is related to reduction of chain-reactive hydroxyl radical production in oligodendrocytes.

Evidence of motor-control difficulties in children with attention deficit hyperactivity disorder, explored through a hierarchical motor-systems perspective.

PubMed

Macoun, Sarah J; Kerns, Kimberly A

2016-01-01

Attention deficit hyperactivity disorder (ADHD) may reflect a disorder of neural systems that regulate motor control. The current study investigates motor dysfunction in children with ADHD using a hierarchical motor-systems perspective where frontal-striatal/"medial" brain systems are viewed as regulating parietal/"lateral" brain systems in a top down manner, to inhibit automatic environmentally driven responses in favor of goal-directed behavior. It was hypothesized that due to frontal-striatal hypoactivation, children with ADHD would have difficulty with higher order motor control tasks felt to be dependent on these systems, yet have preserved general motor function. A total of 63 children-ADHD and matched controls-completed experimental motor tasks that required maintenance of internal motor representations and the ability to inhibit visually driven responses. Children also completed a measure of motor inhibition, and a portion of the sample completed general motor function tasks. On motor tasks that required them to maintain internal motor representations and to inhibit automatic motor responses, children with ADHD had significantly greater difficulty than controls, yet on measures of general motor dexterity, their performance was comparable. Children with ADHD displayed significantly greater intraindividual (subject) variability than controls. Intraindividual variability (IIV) contributed to variations in performance across the motor tasks, but did not account for all of the variance on all tasks. These findings suggest that children with ADHD may be more controlled by external stimuli than by internally represented information, possibly due to dysfunction of the medial motor system. However, it is likely that children with ADHD also display general motor-execution problems (as evidenced by IIV findings), suggesting that atypicalities may extend to both medial and lateral motor systems. Findings are interpreted within the context of contemporary theories regarding motor dysfunction in ADHD, and implications for understanding externalizing behaviors in ADHD are discussed.

Medical and surgical management of esophageal and gastric motor dysfunction.

PubMed

Awad, R A

2012-09-01

he occurrence of esophageal and gastric motor dysfunctions happens, when the software of the esophagus and the stomach is injured. This is really a program previously established in the enteric nervous system as a constituent of the newly called neurogastroenterology. The enteric nervous system is composed of small aggregations of nerve cells, enteric ganglia, the neural connections between these ganglia, and nerve fibers that supply effectors tissues, including the muscle of the gut wall. The wide range of enteric neuropathies that includes esophageal achalasia and gastroparesis highlights the importance of the enteric nervous system. A classification of functional gastrointestinal disorders based on symptoms has received attention. However, a classification based solely in symptoms and consensus may lack an integral approach of disease. As an alternative to the Rome classification, an international working team in Bangkok presented a classification of motility disorders as a physiology-based diagnosis. Besides, the Chicago Classification of esophageal motility was developed to facilitate the interpretation of clinical high-resolution esophageal pressure topography studies. This review covers exclusively the medical and surgical management of the esophageal and gastric motor dysfunction using evidence from well-designed studies. Motor control of the esophagus and the stomach, motor esophageal and gastric alterations, treatment failure, side effects of PPIs, overlap of gastrointestinal symptoms, predictors of treatment, burden of GERD medical management, data related to conservative treatment vs. antireflux surgery, and postsurgical esophagus and gastric motor dysfunction are also taken into account.

Transcranial magnetic stimulation as an investigative tool for motor dysfunction and recovery in stroke: an overview for neurorehabilitation clinicians

PubMed Central

Cortes, Mar; Black-Schaffer, Randie M; Edwards, Dylan J

2012-01-01

Rationale An improved understanding of motor dysfunction and recovery after stroke has important clinical implications that may lead to the design of more effective rehabilitation strategies for patients with hemiparesis. Scope Transcranial magnetic stimulation (TMS) is a safe and painless tool that has been used in conjunction with other existing diagnostic tools to investigate motor pathophysiology in stroke patients. Since TMS emerged over two decades ago, its application in clinical and basic neuroscience has expanded worldwide. TMS can quantify the corticomotor excitability properties of clinically affected and unaffected muscles, and probe local cortical networks, as well as remote but functionally related areas. This provides novel insight into the physiology of neural circuits underlying motor dysfunction, and brain reorganization during the motor recovery process. This important tool needs to be used with caution by clinical investigators, its limitations need to be understood and the results should be interpreted along with clinical evaluation in this patient population. Summary In this review, we provide an overview of the rationale, implementation and limitations of TMS to study stroke motor physiology. This knowledge may be useful to guide future rehabilitation treatments by assessing and promoting functional plasticity. PMID:22624621

SPEEDY babies: A putative new behavioral syndrome of unbalanced motor-speech development

PubMed Central

Haapanen, Marja-Leena; Aro, Tuomo; Isotalo, Elina

2008-01-01

Even though difficulties in motor development in children with speech and language disorders are widely known, hardly any attention is paid to the association between atypically rapidly occurring unassisted walking and delayed speech development. The four children described here presented with a developmental behavioral triad: 1) atypically speedy motor development, 2) impaired expressive speech, and 3) tongue carriage dysfunction resulting in related misarticulations. Those characteristics might be phenotypically or genetically clustered. These children didn’t have impaired cognition, neurological or mental disease, defective sense organs, craniofacial dysmorphology or susceptibility to upper respiratory infections, particularly recurrent otitis media. Attention should be paid on discordant and unbalanced achievement of developmental milestones. Present children are termed SPEEDY babies, where SPEEDY refers to rapid independent walking, SPEE and DY to dyspractic or dysfunctional speech development and lingual dysfunction resulting in linguoalveolar misarticulations. SPEEDY babies require health care that recognizes and respects their motor skills and supports their needs for motor activities and on the other hand include treatment for impaired speech. The parents may need advice and support with these children. PMID:19337462

Low signal intensity in motor cortex on susceptibility-weighted MR imaging is correlated with clinical signs of amyotrophic lateral sclerosis: a pilot study.

PubMed

Endo, Hironobu; Sekiguchi, Kenji; Shimada, Hitoshi; Ueda, Takehiro; Kowa, Hisatomo; Kanda, Fumio; Toda, Tatsushi

2018-03-01

There is no reliable objective indicator for upper motor neuron dysfunction in amyotrophic lateral sclerosis (ALS). To determine the clinical significance and potential utility of magnetic resonance (MR) signals, we investigated the relationship between clinical symptoms and susceptibility changes in the motor cortex measured using susceptibility-weighted MR imaging taken by readily available 3-T MRI in clinical practice. Twenty-four ALS patients and 14 control subjects underwent 3-T MR T1-weighted imaging and susceptibility-weighted MR imaging with the principles of echo-shifting with a train of observations (PRESTO) sequence. We analysed relationships between relative susceptibility changes in the motor cortex assessed using voxel-based analysis (VBA) and clinical scores, including upper motor neuron score, ALS functional rating scale revised score, and Medical Research Council sum score on physical examination. Patients with ALS exhibited significantly lower signal intensity in the precentral gyrus on susceptibility-weighted MR imaging compared with controls. Clinical scores were significantly correlated with susceptibility changes. Importantly, the extent of the susceptibility changes in the bilateral precentral gyri was significantly correlated with upper motor neuron scores. The results of our pilot study using VBA indicated that low signal intensity in motor cortex on susceptibility-weighted MR imaging may correspond to clinical symptoms, particularly upper motor neuron dysfunction. Susceptibility-weighted MR imaging may be a useful diagnostic tool as an objective indicator of upper motor neuron dysfunction.

Development of the Korean Academy of Medical Sciences Guideline for Rating the Impairment in the Brain Injured and Brain Diseased Persons with Motor Dysfunction

PubMed Central

Baik, Jong Sam; Jang, Seong Ho; Park, Dong Sik

2009-01-01

To develop an objective and scientific method to evaluate the brain injured and brain diseased persons with motor dysfunction, American Medical Association's Guides to the Evaluation of Permanent Impairment was used as an exemplar. After the motor dysfunction due to brain injury or brain disease was confirmed, active range of motion and muscle strength of affected extremities were measured. Also, the total function of extremities was evaluated through the assessment of activities of daily living, fine coordination of hand, balance and gait. Then, the total score of manual muscle test and functional assessment of impaired upper and lower extremity were added, respectively. Spasticity of upper and lower extremity was used as minus factors. Patients with movement disorder such as Parkinson's disease were assessed based on the degree of dysfunction in response to medication. We develop a new rating system based on the concept of total score. PMID:19503680

A case for motor network contributions to schizophrenia symptoms: Evidence from resting-state connectivity.

PubMed

Bernard, Jessica A; Goen, James R M; Maldonado, Ted

2017-09-01

Though schizophrenia (SCZ) is classically defined based on positive symptoms and the negative symptoms of the disease prove to be debilitating for many patients, motor deficits are often present as well. A growing literature highlights the importance of motor systems and networks in the disease, and it may be the case that dysfunction in motor networks relates to the pathophysiology and etiology of SCZ. To test this and build upon recent work in SCZ and in at-risk populations, we investigated cortical and cerebellar motor functional networks at rest in SCZ and controls using publically available data. We analyzed data from 82 patients and 88 controls. We found key group differences in resting-state connectivity patterns that highlight dysfunction in motor circuits and also implicate the thalamus. Furthermore, we demonstrated that in SCZ, these resting-state networks are related to both positive and negative symptom severity. Though the ventral prefrontal cortex and corticostriatal pathways more broadly have been implicated in negative symptom severity, here we extend these findings to include motor-striatal connections, as increased connectivity between the primary motor cortex and basal ganglia was associated with more severe negative symptoms. Together, these findings implicate motor networks in the symptomatology of psychosis, and we speculate that these networks may be contributing to the etiology of the disease. Overt motor deficits in SCZ may signal underlying network dysfunction that contributes to the overall disease state. Hum Brain Mapp 38:4535-4545, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The temporal profile of the reaction of microglia, astrocytes, and macrophages in the delayed onset paraplegia after transient spinal cord ischemia in rabbits.

PubMed

Matsumoto, Satoshi; Matsumoto, Mishiya; Yamashita, Atsuo; Ohtake, Kazunobu; Ishida, Kazuyoshi; Morimoto, Yasuhiro; Sakabe, Takefumi

2003-06-01

In the present study, we sought to elucidate the temporal profile of the reaction of microglia, astrocytes, and macrophages in the progression of delayed onset motor dysfunction after spinal cord ischemia (15 min) in rabbits. At 2, 4, 8, 12, 24, and 48 h after reperfusion (9 animals in each), hind limb motor function was assessed, and the lumbar spinal cord was histologically examined. Delayed motor dysfunction was observed in most animals at 48 h after ischemia, which could be predicted by a poor recovery of segmental spinal cord evoked potentials at 15 min of reperfusion. In the gray matter of the lumbar spinal cord, both microglia and astrocytes were activated early (2 h) after reperfusion. Microglia were diffusely activated and engulfed motor neurons irrespective of the recovery of segmental spinal cord evoked potentials. In contrast, early astrocytic activation was confined to the area where neurons started to show degeneration. Macrophages were first detected at 8 h after reperfusion and mainly surrounded the infarction area later. Although the precise roles of the activation of microglia, astrocytes, and macrophages are to be further determined, the results indicate that understanding functional changes of astrocytes may be important in the mechanism of delayed onset motor dysfunction including paraplegia. Microglia and macrophages play a role in removing tissue debris after transient spinal cord ischemia. Disturbance of astrocytic defense mechanism, breakdown of the blood-spinal cord barrier, or both seemed to be involved in the development of delayed motor dysfunction.

Lower urinary tract dysfunction in critical illness polyneuropathy.

PubMed

Reitz, André

2013-01-01

Critical illness polyneuropathy is a frequent complication of critical illness in intensive care units. Reports on autonomic systems like lower urinary tract and bowel functions in patients with CIP are not available in medical literature. This study performed during primary rehabilitation of patients with critical illness polyneuropathy explores if sensory and motor pathways controlling the lower urinary tract function are affected from the disease. Neurourological examinations, urodynamics, electromyography and lower urinary tract imaging were performed in 28 patients with critical illness polyneuropathy. Sacral sensation was impaired in 1 patient (4%). Sacral reflexes were absent in 8 patients (30%). Anal sphincter resting tone was reduced in 3 (12%), anal sphincter voluntary contraction was absent or reduced in 8 patients (30%). Urodynamic findings were detrusor overactivity and detrusor overactivity incontinence in 9 (37.5%), incomplete voiding in 8 (30%), abnormal sphincter activity in 4 (16%), abnormal bladder sensation in 4 (16%) and detrusor acontractility in 2 patients (8.3%). Morphological abnormalities of the lower urinary tract had 10 patients (41.6%). Sensory and motor pathways controlling the lower urinary tract might be affected from CIP. During urodynamics dysfunctions of the storage as well as the voiding phase were found. Morphological lower urinary tract abnormalities were common.

Kinematical analysis of handwriting movements in depressed patients.

PubMed

Mergl, R; Juckel, G; Rihl, J; Henkel, V; Karner, M; Tigges, P; Schröter, A; Hegerl, U

2004-05-01

Motor disturbances are a relevant aspect of depression. Kinematical analysis of movements can be applied to explore which type of motor dysfunction is associated with depression. We hypothesized that depressed patients draw and write significantly slower than controls and that motor disturbances become more pronounced under bi-manual demands. We examined 37 depressed patients and 37 healthy controls using a digitizing graphic tablet and subsequent kinematical analysis of handwriting and rapid drawing movements. Depressed patients performed drawing with significantly less regular velocity than controls (P < 0.001), but normal velocity. Motor differences between patients and controls did not increase under bi-manual demands. Handwriting of patients was abnormally slow (P = 0.04). Irregular patterns of velocity peaks in depressed patients point to basal ganglia dysfunction and/or deficient activity of the sensorimotor cortex and the supplementary motor area as a possible substrate of hand-motor disturbances in depression.

Basal ganglia and beyond: The interplay between motor and cognitive aspects in Parkinson's disease rehabilitation.

PubMed

Ferrazzoli, Davide; Ortelli, Paola; Madeo, Graziella; Giladi, Nir; Petzinger, Giselle M; Frazzitta, Giuseppe

2018-07-01

Parkinson's disease (PD) is characterized by motor and cognitive dysfunctions, affecting the motor behaviour. We summarize evidence that the interplay between motor and cognitive approaches is crucial in PD rehabilitation. Rehabilitation is complementary to pharmacological therapy and effective in reducing the PD disturbances, probably acting by inducing neuroplastic effects. The motor behaviour results from a complex integration between cortical and subcortical areas, underlying the motor, cognitive and motivational aspects of movement. The close interplay amongst these areas makes possible to learn, control and express habitual-automatic actions, which are dysfunctional in PD. The physiopathology of PD could be considered the base for the development of effective rehabilitation treatments. As the volitional action control is spared in early-medium stages of disease, rehabilitative approaches engaging cognition permit to achieve motor benefits and appear to be the most effective for PD. We will point out data supporting the relevance of targeting both motor and cognitive aspects in PD rehabilitation. Finally, we will discuss the role of cognitive engagement in motor rehabilitation for PD. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Primary Lateral Sclerosis.

PubMed

Statland, Jeffrey M; Barohn, Richard J; Dimachkie, Mazen M; Floeter, Mary Kay; Mitsumoto, Hiroshi

2015-11-01

Primary lateral sclerosis is characterized by insidious onset of progressive upper motor neuron dysfunction in the absence of clinical signs of lower motor neuron involvement. Patients experience stiffness; decreased balance and coordination; mild weakness; and, if the bulbar region is affected, difficulty speaking and swallowing, and emotional lability. The diagnosis is made based on clinical history, typical examination findings, and diagnostic testing negative for other causes of upper motor neuron dysfunction. Electromyogram is normal, or only shows mild neurogenic findings in a few muscles, not meeting El Escorial criteria. Treatment is largely supportive. Copyright © 2015 Elsevier Inc. All rights reserved.

Reduced sensory synaptic excitation impairs motor neuron function via Kv2.1 in spinal muscular atrophy.

PubMed

Fletcher, Emily V; Simon, Christian M; Pagiazitis, John G; Chalif, Joshua I; Vukojicic, Aleksandra; Drobac, Estelle; Wang, Xiaojian; Mentis, George Z

2017-07-01

Behavioral deficits in neurodegenerative diseases are often attributed to the selective dysfunction of vulnerable neurons via cell-autonomous mechanisms. Although vulnerable neurons are embedded in neuronal circuits, the contributions of their synaptic partners to disease process are largely unknown. Here we show that, in a mouse model of spinal muscular atrophy (SMA), a reduction in proprioceptive synaptic drive leads to motor neuron dysfunction and motor behavior impairments. In SMA mice or after the blockade of proprioceptive synaptic transmission, we observed a decrease in the motor neuron firing that could be explained by the reduction in the expression of the potassium channel Kv2.1 at the surface of motor neurons. Chronically increasing neuronal activity pharmacologically in vivo led to a normalization of Kv2.1 expression and an improvement in motor function. Our results demonstrate a key role of excitatory synaptic drive in shaping the function of motor neurons during development and the contribution of its disruption to a neurodegenerative disease.

Reduced sensory synaptic excitation impairs motor neuron function via Kv2.1 in spinal muscular atrophy

PubMed Central

Fletcher, Emily V.; Simon, Christian M.; Pagiazitis, John G.; Chalif, Joshua I.; Vukojicic, Aleksandra; Drobac, Estelle; Wang, Xiaojian; Mentis, George Z.

2017-01-01

Behavioral deficits in neurodegenerative diseases are often attributed to the selective dysfunction of vulnerable neurons via cell-autonomous mechanisms. Although vulnerable neurons are embedded in neuronal circuits, the contribution of their synaptic partners to the disease process is largely unknown. Here, we show that in a mouse model of spinal muscular atrophy (SMA), a reduction in proprioceptive synaptic drive leads to motor neuron dysfunction and motor behavior impairments. In SMA mice or after the blockade of proprioceptive synaptic transmission we observed a decrease in the motor neuron firing which could be explained by the reduction in the expression of the potassium channel Kv2.1 at the surface of motor neurons. Increasing neuronal activity pharmacologically by chronic exposure in vivo led to a normalization of Kv2.1 expression and an improvement in motor function. Our results demonstrate a key role of excitatory synaptic drive in shaping the function of motor neurons during development and the contribution of its disruption to a neurodegenerative disease. PMID:28504671

Motor Learning Versus StandardWalking Exercise in Older Adults with Subclinical Gait Dysfunction: A Randomized Clinical Trial

PubMed Central

Brach, Jennifer S.; Van Swearingen, Jessie M.; Perera, Subashan; Wert, David M.; Studenski, Stephanie

2013-01-01

Background Current exercise recommendationsfocus on endurance and strength, but rarely incorporate principles of motor learning. Motor learning exerciseis designed to address neurological aspects of movement. Motor learning exercise has not been evaluated in older adults with subclinical gait dysfunction. Objectives Tocompare motor learning versus standard exercise on measures of mobility and perceived function and disability. Design Single-blind randomized trial. Setting University research center. Participants Olderadults (n=40), mean age 77.1±6.0 years), who had normal walking speed (≥1.0 m/s) and impaired motor skill (Figure of 8 walk time > 8 s). Interventions The motor learning program (ML) incorporated goal-oriented stepping and walking to promote timing and coordination within the phases of the gait cycle. The standard program (S) employed endurance training by treadmill walking.Both included strength training and were offered twice weekly for one hour for 12 weeks. Measurements Primary outcomes included mobility performance (gait efficiency, motor skill in walking, gait speed, and walking endurance)and secondary outcomes included perceived function and disability (Late Life Function and Disability Instrument). Results 38 of 40 participants completed the trial (ML, n=18; S, n=20). ML improved more than Sin gait speed (0.13 vs. 0.05 m/s, p=0.008) and motor skill (−2.2 vs. −0.89 s, p<0.0001). Both groups improved in walking endurance (28.3 and 22.9m, but did not differ significantly p=0.14). Changes in gait efficiency and perceived function and disability were not different between the groups (p>0.10). Conclusion In older adults with subclinical gait dysfunction, motor learning exercise improved some parameters of mobility performance more than standard exercise. PMID:24219189

Striatal dysfunction increases basal ganglia output during motor cortex activation in parkinsonian rats.

PubMed

Belluscio, Mariano A; Riquelme, Luis A; Murer, M Gustavo

2007-05-01

During movement, inhibitory neurons in the basal ganglia output nuclei show complex modulations of firing, which are presumptively driven by corticostriatal and corticosubthalamic input. Reductions in discharge should facilitate movement by disinhibiting thalamic and brain stem nuclei while increases would do the opposite. A proposal that nigrostriatal dopamine pathway degeneration disrupts trans-striatal pathways' balance resulting in sustained overactivity of basal ganglia output nuclei neurons and Parkinson's disease clinical signs is not fully supported by experimental evidence, which instead shows abnormal synchronous oscillatory activity in animal models and patients. Yet, the possibility that variation in motor cortex activity drives transient overactivity in output nuclei neurons in parkinsonism has not been explored. In Sprague-Dawley rats with 6-hydroxydopamine (6-OHDA)-induced nigrostriatal lesions, approximately 50% substantia nigra pars reticulata (SNpr) units show abnormal cortically driven slow oscillations of discharge. Moreover, these units selectively show abnormal responses to motor cortex stimulation consisting in augmented excitations of an odd latency, which overlapped that of inhibitory responses presumptively mediated by the trans-striatal direct pathway in control rats. Delivering D1 or D2 dopamine agonists into the striatum of parkinsonian rats by reverse microdialysis reduced these abnormal excitations but had no effect on pathological oscillations. The present study establishes that dopamine-deficiency related changes of striatal function contribute to producing abnormally augmented excitatory responses to motor cortex stimulation in the SNpr. If a similar transient overactivity of basal ganglia output were driven by motor cortex input during movement, it could contribute to impeding movement initiation or execution in Parkinson's disease.

Neural Underpinnings of Impaired Predictive Motor Timing in Children with Developmental Coordination Disorder

ERIC Educational Resources Information Center

Debrabant, Julie; Gheysen, Freja; Caeyenberghs, Karen; Van Waelvelde, Hilde; Vingerhoets, Guy

2013-01-01

A dysfunction in predictive motor timing is put forward to underlie DCD-related motor problems. Predictive timing allows for the pre-selection of motor programmes (except "program" in computers) in order to decrease processing load and facilitate reactions. Using functional magnetic resonance imaging (fMRI), this study investigated the neural…

Effects of Levodopa on Vowel Articulation in Patients with Parkinson's Disease.

PubMed

Okada, Yukihiro; Murata, Miho; Toda, Tatsushi

2016-04-27

The effects of levodopa on articulatory dysfunction in patients with Parkinson's disease remain inconclusive. This study aimed to investigate the effects of levodopa on isolated vowel articulation and motor performance in patients with moderate to severe Parkinson's disease, excluding speech fluctuations caused by dyskinesia. 21 patients (14 males and 7 females) and 21 age- and sex- matched healthy subjects were enrolled. Together with motor assessment, the patients phonated five Japanese isolated vowels (/a/, /i/, /u/, /e/, and /o/) 20 times before and 1 h after levodopa treatment. We made the frequency analysis of each vowel and measured the first and second formants. From these formants we constructed the pentagonal vowel space area which should be the good indicator for articulatory dysfunction of vowels. In control subjects, only speech samples were analyzed. To investigate the sequential relationship between plasma levodopa concentrations, motor performances, and acoustic measurements after treatment, entire drug cycle tests were performed in 4 patients. The pentagonal vowel space area was significantly expanded together with motor amelioration after levodopa treatment, although the enlargement is not enough for the space area of control subjects. Drug cycle tests revealed that sequential increases or decreases in plasma levodopa levels after treatment correlated well with expansion or decrease of the vowel space areas and improvement or deterioration of motor manifestations. Levodopa expanded the vowel space area and ameliorated motor performance, suggesting that dysfunctions in vowel articulation and motor performance in patients with Parkinson's disease are based on dopaminergic pathology.

Pen-2 overexpression induces Aβ-42 production, memory defect, motor activity enhancement and feeding behavior dysfunction in NSE/Pen-2 transgenic mice.

PubMed

Nam, So Hee; Seo, Su Jin; Goo, Jun Seo; Kim, Jee Eun; Choi, Sun Il; Lee, Hae Ryun; Hwang, In Sik; Jee, Seung Wan; Lee, Su Hae; Bae, Chang Jun; Park, Jung Youn; Kim, Hye Sung; Shim, Sun Bo; Hwang, Dae Youn

2011-12-01

Pen-2 is a key regulator of the γ-secretase complex, which is involved in the production of the amyloid β (Aβ)-42 peptides, which ultimately lead to Alzheimer's disease (AD). While Pen-2 has been studied in vitro, Pen-2 function in vivo in the brains of transgenic (Tg) mice overexpressing human Pen-2 (hPen-2) protein has not been studied. This study aimed to determine whether Pen-2 overexpression could regulate the AD-like phenotypes in Tg mice. NSE/hPen-2 Tg mice were produced by the microinjection of the NSE/hPen-2 gene into the pronucleus of fertilized eggs. The expression of the hPen-2 gene under the control of the NSE promoter was successfully detected only in the brain and kidney tissue of NSE/hPen-2 Tg mice. Also, 12-month-old NSE/hPen-2 Tg mice displayed behavioral dysfunction in the water maze test, motor activity and feeding behavior dysfunction in food intake/water intake/motor activity monitoring system. In addition, tissue samples displayed dense staining with antibody to the Aβ-42 peptide. Furthermore, NSE/hPen-2 Tg mice exhibiting feeding behavior dysfunction were significantly more apt to display symptoms related to diabetes and obesity. These results suggest that Pen-2 overexpression in NSE/hPen-2 Tg mice may induce all the AD-like phenotypes, including behavioral deficits, motor activity and feeding behavior dysfunction, Aβ-42 peptide deposition and chronic disease induction.

[The optimization of restoration approaches of advanced hand activity using the sensorial glove and the mCIMT method].

PubMed

Mozheiko, E Yu; Prokopenko, S V; Alekseevich, G V

To reason the choice of methods of restoration of advanced hand activity depending on severity of motor disturbance in the top extremity. Eighty-eight patients were randomized into 3 groups: 1) the mCIMT group, 2) the 'touch glove' group, 3) the control group. For assessment of physical activity of the top extremity Fugl-Meyer Assessment Upper Extremity, Nine-Hole Peg Test, Motor Assessment Scale were used. Assessment of non-use phenomenon was carried out with the Motor Activity Log scale. At a stage of severe motor dysfunction, there was a restoration of proximal departments of a hand in all groups, neither method was superior to the other. In case of moderate severity of motor deficiency of the upper extremity the most effective was the method based on the principle of biological feedback - 'a touch glove'. In the group with mild severity of motor dysfunction, the best recovery was achieved in the mCIMT group.

Infant Motor Skills After a Cardiac Operation: The Need for Developmental Monitoring and Care.

PubMed

Uzark, Karen; Smith, Cynthia; Donohue, Janet; Yu, Sunkyung; Romano, Jennifer C

2017-08-01

Neurodevelopmental dysfunction is increasingly recognized as a common outcome of congenital heart defects and their treatment in infancy. The effects of the intensive care unit (ICU) experience and environment on these infants are unknown and potentially modifiable, but no validated metric is available for objective evaluation of early motor impairments in the ICU/hospital setting. The purpose of this study was to characterize the motor status of hospitalized infants after cardiac operations, including the development and field-testing of the Congenital Heart Assessment of Sensory and Motor Status (CHASMS) metric. CHASMS item generation was based on review of the literature, focused interviews with parents, and expert consensus. A nurse administered CHASMS to 100 infants aged younger than 10 months old undergoing cardiac operations. Preoperative and postoperative CHASMS scores were compared, and associations between CHASMS scores and patient characteristics were examined. Physical therapists assessed neuromotor skills by using the Test of Infant Motor Performance or the Alberta Infant Motor Scales for correlation with CHASMS scores. CHASMS gross motor scores declined postoperatively in 64% (25 of 39). Lower CHASMS scores, after adjusting for age, were associated with longer duration of mechanical ventilation (p < 0.001) and ICU length of stay (p = 0.001). Gross motor CHASMS scores were significantly correlated with Test of Infant Motor Performance (r = 0.70, p < 0.001) and Alberta Infant Motor Scales scores (r = 0.88, p < 0.001). Motor impairments in infants after cardiac operations are common and may be exacerbated by longer intubation and prolonged exposure to the ICU environment. The feasibility, reliability, and validity of CHASMS were supported for the evaluation of motor skills in this at-risk population. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Emerging treatment options for spinal muscular atrophy.

PubMed

Burnett, Barrington G; Crawford, Thomas O; Sumner, Charlotte J

2009-03-01

The motor neuron disease spinal muscular atrophy (SMA) is one of the leading genetic killers of infants worldwide. SMA is caused by mutation of the survival motor neuron 1 (SMN1) gene and deficiency of the survival motor neuron (SMN) protein. All patients retain one or more copies of the SMN2 gene, which (by producing a small amount of the SMN protein) rescues embryonic lethality and modifies disease severity. Rapid progress continues in dissecting the cellular functions of the SMN protein, but the mechanisms linking SMN deficiency with dysfunction and loss of functioning motor units remain poorly defined. Clinically, SMA should to be distinguished from other neuromuscular disorders, and the diagnosis can be readily confirmed with genetic testing. Quality of life and survival of SMA patients are improved with aggressive supportive care including optimized respiratory and nutritional care and management of scoliosis and contractures. Because SMA is caused by inadequate amounts of SMN protein, one aim of current SMA therapeutics development is to increase SMN protein levels in SMA patients by activating SMN2 gene expression and/or increasing levels of full-length SMN2 transcripts. Several potential therapeutic compounds are currently being studied in clinical trials in SMA patients.

Focus on autonomic dysfunction in familial amyloidotic polyneuropathy (FAP).

PubMed

Obayashi, Konen; Ando, Yukio

2012-06-01

It is well known that autonomic dysfunction in familial amyloidotic polyneuropathy (FAP) is the most serious problem, because it restricts the daily life of these patients. The detail mechanisms of the onset are not well understood in FAP and domino liver transplantation-induced amyloid neuropathy. As autonomic disturbances play an important role in the symptomatology of FAP, further studies of autonomic dysfunction in these patients may lead the pathogenesis of FAP. Autonomic dysfunction is often observed before sensory and motor nerve dysfunction in FAP. This can be attributed to the morphological characteristics of the nerves. Unmyelinated, small myelinated, and large myelinated fibers tend to become impaired in that order. Although the reasons of susceptibility to amyloid infiltration and injury are not known, studies of autopsied FAP patients have revealed heavy infiltration of amyloid in autonomic ganglions. Moreover, spinal ganglion and posterior loot of the spine had severe amyloid deposits than did the anterior root of the spine or the motor nerves. It is well known that autonomic dysfunction is the most serious problem, because it restricts the daily life of FAP patients. However, we have four major questions about autonomic dysfunction in clinical. In this manuscript, we discuss about the answers of these questions.

Electrophysiological signs of supplementary-motor-area deficits in high-functioning autism but not Asperger syndrome: an examination of internally cued movement-related potentials.

PubMed

Enticott, Peter G; Bradshaw, John L; Iansek, Robert; Tonge, Bruce J; Rinehart, Nicole J

2009-10-01

Motor dysfunction is common to both autism and Asperger syndrome, but the underlying neurophysiological impairments are unclear. Neurophysiological examinations of motor dysfunction can provide information about likely sites of functional impairment and can contribute to the debate about whether autism and Asperger syndrome are variants of the same disorder or fundamentally distinct neurodevelopmental conditions. We investigated the neurophysiology of internally determined motor activity in autism and Asperger syndrome via examination of movement-related potentials (MRPs). We used electroencephalography to investigate MRPs, via an internally cued movement paradigm, in the following three groups: (1) individuals with high-functioning autism (14 males, one female; mean age 13 y 1 mo, SD 4 y 2 mo, range 7 y 8 mo to 20 y 9 mo; mean Full-scale IQ 93.40, SD 20.72); (2) individuals with Asperger syndrome (10 males, two females; mean age 13 y 7 mo, SD 3 y 9 mo, range 8 y 11 mo to 20 y 4 mo; mean Full-scale IQ 103.25, SD 19.37), and (3) a healthy control group (13 males, seven females; mean age 14 y 0 mo, SD 3 y 11 mo; range 8 y 4 mo to 21 y 0 mo; mean Full-scale IQ 114.25, SD 11.29). Abnormal MRPs can reflect disruption of motor-related neural networks involving the basal ganglia, thalamus, and supplementary motor area. There was evidence for abnormal MRPs in autism (e.g. increased post-movement cortical activity, abnormal peak time) but not in Asperger syndrome. The results support basal ganglia, thalamus, and supplementary motor area involvement as a likely source of motor dysfunction in autism, and provide further evidence for the neurobiological separateness of autism and Asperger syndrome.

Rethinking energy in parkinsonian motor symptoms: a potential role for neural metabolic deficits

PubMed Central

Amano, Shinichi; Kegelmeyer, Deborah; Hong, S. Lee

2015-01-01

Parkinson’s disease (PD) is characterized as a chronic and progressive neurodegenerative disorder that results in a variety of debilitating symptoms, including bradykinesia, resting tremor, rigidity, and postural instability. Research spanning several decades has emphasized basal ganglia dysfunction, predominantly resulting from dopaminergic (DA) cell loss, as the primarily cause of the aforementioned parkinsonian features. But, why those particular features manifest themselves remains an enigma. The goal of this paper is to develop a theoretical framework that parkinsonian motor features are behavioral consequence of a long-term adaptation to their inability (inflexibility or lack of capacity) to meet energetic demands, due to neural metabolic deficits arising from mitochondrial dysfunction associated with PD. Here, we discuss neurophysiological changes that are generally associated with PD, such as selective degeneration of DA neurons in the substantia nigra pars compacta (SNc), in conjunction with metabolic and mitochondrial dysfunction. We then characterize the cardinal motor symptoms of PD, bradykinesia, resting tremor, rigidity and gait disturbance, reviewing literature to demonstrate how these motor patterns are actually energy efficient from a metabolic perspective. We will also develop three testable hypotheses: (1) neural metabolic deficits precede the increased rate of neurodegeneration and onset of behavioral symptoms in PD; (2) motor behavior of persons with PD are more sensitive to changes in metabolic/bioenergetic state; and (3) improvement of metabolic function could lead to better motor performance in persons with PD. These hypotheses are designed to introduce a novel viewpoint that can elucidate the connections between metabolic, neural and motor function in PD. PMID:25610377

Improvement in Stroke-induced Motor Dysfunction by Music-supported Therapy: A Systematic Review and Meta-analysis

PubMed Central

Zhang, Yingshi; Cai, Jiayi; Zhang, Yaqiong; Ren, Tianshu; Zhao, Mingyi; Zhao, Qingchun

2016-01-01

To conduct a meta-analysis of clinical trials that examined the effect of music-supported therapy on stroke-induced motor dysfunction, comprehensive literature searches of PubMed, Embase and the Cochrane Library from their inception to April 2016 were performed. A total of 10 studies (13 analyses, 358 subjects) were included; all had acceptable quality according to PEDro scale score. The baseline differences between the two groups were confirmed to be comparable. Compared with the control group, the standardized mean difference of 9-Hole Peg Test was 0.28 (−0.01, 0.57), 0.64 (0.31, 0.97) in Box and Block Test, 0.47 (0.08, 0.87) in Arm Paresis Score and 0.35 (−0.04, 0.75) in Action Research Arm Test for upper-limb motor function, 0.11 (−0.24, 0.46) in Berg Balance Scale score, 0.09 (−0.36, 0.54) in Fugl-Meyer Assessment score, 0.30 (−0.15, 0.74) in Wolf Motor Function Test, 0.30 (−0.15, 0.74) in Wolf Motor Function time, 0.65 (0.14, 1.16) in Stride length and 0.62 (0.01, 1.24) in Gait Velocity for total motor function, and 1.75 (0.94, 2.56) in Frontal Assessment Battery score for executive function. There was evidence of a positive effect of music-supported therapy, supporting its use for the treatment of stroke-induced motor dysfunction. This study was registered at PRESPERO (CRD42016037106). PMID:27917945

Time-Restricted Feeding Improves Circadian Dysfunction as well as Motor Symptoms in the Q175 Mouse Model of Huntington's Disease.

PubMed

Wang, Huei-Bin; Loh, Dawn H; Whittaker, Daniel S; Cutler, Tamara; Howland, David; Colwell, Christopher S

2018-01-01

Huntington's disease (HD) patients suffer from a progressive neurodegeneration that results in cognitive, psychiatric, cardiovascular, and motor dysfunction. Disturbances in sleep/wake cycles are common among HD patients with reports of delayed sleep onset, frequent bedtime awakenings, and fatigue during the day. The heterozygous Q175 mouse model of HD has been shown to phenocopy many HD core symptoms including circadian dysfunctions. Because circadian dysfunction manifests early in the disease in both patients and mouse models, we sought to determine if early intervention that improve circadian rhythmicity can benefit HD and delay disease progression. We determined the effects of time-restricted feeding (TRF) on the Q175 mouse model. At six months of age, the animals were divided into two groups: ad libitum (ad lib) and TRF. The TRF-treated Q175 mice were exposed to a 6-h feeding/18-h fasting regimen that was designed to be aligned with the middle of the time when mice are normally active. After three months of treatment (when mice reached the early disease stage), the TRF-treated Q175 mice showed improvements in their locomotor activity rhythm and sleep awakening time. Furthermore, we found improved heart rate variability (HRV), suggesting that their autonomic nervous system dysfunction was improved. Importantly, treated Q175 mice exhibited improved motor performance compared to untreated Q175 controls, and the motor improvements were correlated with improved circadian output. Finally, we found that the expression of several HD-relevant markers was restored to WT levels in the striatum of the treated mice using NanoString gene expression assays.

Side of symptom onset affects motor dysfunction in Parkinson's disease.

PubMed

Haaxma, C A; Helmich, R C G; Borm, G F; Kappelle, A C; Horstink, M W I M; Bloem, B R

2010-11-10

The healthy brain appears to have an asymmetric dopamine distribution, with higher levels of dopamine in the left than in the right striatum. Here, we test the hypothesis that this neurochemical asymmetry renders the right striatum relatively more vulnerable to the effects of dopaminergic denervation in Parkinson's disease (PD). Using the pegboard dexterity test, we compared motor performance of both hands between healthy subjects (n=48), PD patients with predominantly right-hemispheric dopamine depletion (PD-RIGHT; n=83) and PD patients with more severe left-hemispheric dopamine depletion (PD-LEFT; n=103). All subjects were right-handed. After adjusting for hand-dominance effects, we found that PD-RIGHT patients exhibited a 55% larger difference between right and left dexterity scores than PD-LEFT patients. This effect could be attributed to greater motor dysfunction of the more-affected hand in PD-RIGHT patients, while the less-affected hand performed similarly in both groups. We conclude that the side of symptom onset affects motor dysfunction in PD, and suggest that the non-dominant right hemisphere may be more susceptible to dopaminergic denervation than the dominant left hemisphere. Copyright © 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Motor learning in animal models of Parkinson’s Disease: Aberrant synaptic plasticity in the motor cortex

PubMed Central

Xu, Tonghui; Wang, Shaofang; Lalchandani, Rupa R.; Ding, Jun B

2017-01-01

In Parkinson’s disease (PD), dopamine depletion causes dramatic changes in the brain resulting in debilitating cognitive and motor deficits. PD neuropathology has been restricted to postmortem examinations, which are limited to only a single time point of PD progression. Models of PD where dopamine tone in the brain are chemically or physically disrupted are valuable tools in understanding the mechanisms of the disease. The basal ganglia have been well studied in the context of PD, and circuit changes in response to dopamine loss have been linked to the motor dysfunctions in PD. However, the etiology of the cognitive dysfunctions that are comorbid in PD patients has remained unclear until now. In this paper, we review recent studies exploring how dopamine depletion affects the motor cortex at the synaptic level. In particular, we highlight our recent findings on abnormal spine dynamics in the motor cortex of PD mouse models through in vivo, time-lapse imaging and motor-skill behavior assays. In combination with previous studies, a role of the motor cortex in skill-learning, and the impairment of this ability with the loss of dopamine, is becoming more apparent. Taken together, we conclude with a discussion on the potential role for the motor cortex in the motor-skill learning and cognitive impairments of PD, with the possibility of targeting the motor cortex for future PD therapeutics. PMID:28343366

MotorSense: Using Motion Tracking Technology to Support the Identification and Treatment of Gross-Motor Dysfunction.

PubMed

Arnedillo-Sánchez, Inmaculada; Boyle, Bryan; Bossavit, Benoît

2017-01-01

MotorSense is a motion detection and tracking technology that can be implemented across a range of environments to assist in detecting delays in gross-motor skills development. The system utilises the motion tracking functionality of Microsoft's Kinect™. It features games that require children to perform graded gross-motor tasks matched with their chronological and developmental ages. This paper describes the rationale for MotorSense, provides an overview of the functionality of the system and illustrates sample activities.

Neuromotor outcomes at school age after extremely low birth weight: early detection of subtle signs.

PubMed

Gidley Larson, Jennifer C; Baron, Ida Sue; Erickson, Kristine; Ahronovich, Margot D; Baker, Robin; Litman, Fern R

2011-01-01

Motor impairments are prevalent in children born at extremely low birth weight (ELBW; <1,000 g). Rarely studied are subtle motor deficits that indicate dysfunction or delay in neural systems critical for optimal cognitive, academic, and behavioral function. We aimed to examine quantifiable signs of subtle neuromotor dysfunction in an early school-aged ELBW cohort that coincidentally had age-appropriate cognition and design copying. We studied 97 participants born between 1998 and 2001; 74 ELBW (6.7 years ± 0.75) compared with 23 term-born (6.6 years ± 0.29). Neuromotor outcomes were assessed using the Physical and Neurological Examination of Subtle Signs-Revised, and measures of dexterity/coordination and visual-motor integration. ELBW participants performed worse than term-born on design-copying and dexterity, were age-appropriate compared to normative data, and had slower timed movements and more subtle overflow movements. Those ELBW born <26 weeks performed most poorly compared with those born 26-34 weeks and term-born. Subtle motor dysfunctions are detectable and quantifiable in ELBW children by school age, even in the presence of average cognition. Early age assessment of incoordination, motor speed, and overflow movements should aid initiation of timely therapies to prepare at-risk ELBW children for subsequent school entry and facilitate design of optimal early treatment strategies. (c) 2010 APA, all rights reserved.

Quality improvement in neurology: amyotrophic lateral sclerosis quality measures: report of the quality measurement and reporting subcommittee of the American Academy of Neurology.

PubMed

Miller, Robert G; Brooks, Benjamin Rix; Swain-Eng, Rebecca J; Basner, Robert C; Carter, Gregory T; Casey, Patricia; Cohen, Adam B; Dubinsky, Richard; Forshew, Dallas; Jackson, Carlayne E; Kasarskis, Ed; Procaccini, Nicholas J; Sanjak, Mohammed; Tolin, Fredrik P

2013-12-10

Amyotrophic lateral sclerosis (ALS) is a lethal, progressive neurodegenerative disease characterized by loss of motor neurons.(1) Patients with ALS lose function in the limbs, speech, swallowing, and breathing muscles. The cause of the disease is still not known for most patients. Approximately 25,000 people in the United States have ALS, and 5,000 people are diagnosed with ALS annually in the United States.(1) Most patients die from respiratory failure 2 to 5 years after onset of symptoms. Cognitive dysfunction is seen in 20% to 50% of patients.(2) The disease burden for patients and caregivers is enormous. The average cost of care has been estimated at $50,000 per patient per year.(3.)

Primary Lateral Sclerosis

PubMed Central

Statland, Jeffrey M.; Barohn, Richard J.; Dimachkie, Mazen M.; Floeter, Mary Kay; Mitsumoto, Hiroshi

2015-01-01

Synopsis Primary lateral sclerosis (PLS) is characterized by insidious onset of progressive upper motor neuron dysfunction in the absence of clinical signs of lower motor neuron involvement. Patients experience stiffness, decreased balance and coordination, and mild weakness, and if the bulbar region is affected, difficulty speaking and swallowing, and emotional lability. The diagnosis is made based on clinical history, typical exam findings, and diagnostic testing negative for other causes of upper motor neuron dysfunction. EMG is normal, or only shows mild neurogenic findings in a few muscles, not meeting El Escorial criteria. Although no test is specific for PLS, some neurodiagnostic tests are supportive: including absent or delayed central motor conduction times; and changes in the precentral gyrus or corticospinal tracts on MRI, DTI or MR Spectroscopy. Treatment is largely supportive, and includes medications for spasticity, baclofen pump, and treatment for pseudobulbar affect. The prognosis in PLS is more benign than ALS, making this a useful diagnostic category. PMID:26515619

Reduced corticomotor excitability and motor skills development in children born preterm

PubMed Central

Pitcher, Julia B; Schneider, Luke A; Burns, Nicholas R; Drysdale, John L; Higgins, Ryan D; Ridding, Michael C; Nettelbeck, Theodore J; Haslam, Ross R; Robinson, Jeffrey S

2012-01-01

The mechanisms underlying the altered neurodevelopment commonly experienced by children born preterm, but without brain lesions, remain unknown. While individuals born the earliest are at most risk, late preterm children also experience significant motor, cognitive and behavioural dysfunction from school age, and reduced income and educational attainment in adulthood. We used transcranial magnetic stimulation and functional assessments to examine corticomotor development in 151 children without cerebral palsy, aged 10–13 years and born after gestations of 25–41 completed weeks. We hypothesized that motor cortex and corticospinal development are altered in preterm children, which underpins at least some of their motor dysfunction. We report for the first time that every week of reduced gestation is associated with a reduction in corticomotor excitability that remains evident in late childhood. This reduced excitability was associated with poorer motor skill development, particularly manual dexterity. However, child adiposity, sex and socio-economic factors regarding the child's home environment soon after birth were also powerful influences on development of motor skills. Preterm birth was also associated with reduced left hemisphere lateralization, but without increasing the likelihood of being left handed per se. These corticomotor findings have implications for normal motor development, but also raise questions regarding possible longer term consequences of preterm birth on motor function. PMID:22966161

[The clinical phenomenology of Rett's syndrome].

PubMed

Calderón-González, R; Calderón-Sepulveda, R F; Treviño-Welsh, J

1999-01-01

The work was done to facilitate the clinical diagnosis and understanding of Rett syndrome (RS) by grouping the symptoms and signs in areas of neurological disfunction. This is a retrospective, longitudinal and observational study of 30 young females whose clinical manifestations were grouped using a modified Fitzgerald et al. scale for motor and behavior evaluation of patients with RS. All patients were videotaped at least during one or several appointments during their follow-up for a period of 1 to 10 years. All patients and videotapes were reviewed independently by the three authors. We followed the clinical diagnostic criteria of classic RS, and grouped the symptoms and signs in 12 groups of clinical phenomenology that represented specific areas of central or peripheral nervous system involvement: 1) dementia syndrome (fronto-temporo-parietal and limbic dysfunction); 2) extrapyramidal syndrome (basal ganglia dysfunction); 3) respiratory function disorders (brain stem reticular system disfunction); 4) sleep disorders (reticular system and limbic dysfunction); 5) epilepsy (cortico-subcortical paroxysmal bioelectrical dysfunction); 6) lower motor neuron syndrome (neuropathic dysfunction and/or peripheral neuropathy); 7) body growth retardation; 8) tonic-postural skeletal deformities; 9) deficit of pain sensation (nociceptive deficit); 10) pseudobulbar dysfunction; 11) autonomic dysfunction and 12) others (microcephaly and bruxism). In clinical practice, we recommend the use of this grouping of symptoms and signs because it makes facilities the clinical study, definition of areas of dysfunction and diagnosis of the patient with RS.

Gastric motor dysfunctions in Parkinson's disease: Current pre-clinical evidence.

PubMed

Pellegrini, Carolina; Antonioli, Luca; Colucci, Rocchina; Ballabeni, Vigilio; Barocelli, Elisabetta; Bernardini, Nunzia; Blandizzi, Corrado; Fornai, Matteo

2015-12-01

Parkinson's disease (PD) is associated with several non-motor symptoms, such as behavioral changes, urinary dysfunction, sleep disorders, fatigue and, above all, gastrointestinal (GI) dysfunction, including gastric dysmotility, constipation and anorectal dysfunction. Delayed gastric emptying, progressing to gastroparesis, is reported in up to 100% of patients with PD, and it occurs at all stages of the disease with severe consequences to the patient's quality of life. The presence of α-synuclein (α-syn) aggregates in myenteric neurons throughout the digestive tract, as well as morpho-functional alterations of the enteric nervous system (ENS), have been documented in PD. In particular, gastric dysmotility in PD has been associated with an impairment of the brain-gut axis, involving the efferent fibers of the vagal pathway projecting directly to the gastric myenteric plexus. The present review intends to provide an integrated overview of available knowledge on the possible role played by the ENS, considered as a semi-autonomous nervous network, in the pathophysiology of gastric dysmotility in PD. Particular attention has been paid review how translational evidence in humans and studies in pre-clinical models are allowing a better understanding of the functional, neurochemical and molecular alterations likely underlying gastric motor abnormalities occurring in PD. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Effects of Motor Neurone Disease on Language: Further Evidence

ERIC Educational Resources Information Center

Bak, Thomas H.; Hodges, John R.

2004-01-01

It might sound surprising that Motor Neurone Disease (MND), regarded still by many as the very example of a neurodegenerative disease affecting selectively the motor system and sparing the sensory functions as well as cognition, can have a significant influence on language. In this article we hope to demonstrate that language dysfunction is not…

Motor Planning and Control in Autism. A Kinematic Analysis of Preschool Children

ERIC Educational Resources Information Center

Forti, Sara; Valli, Angela; Perego, Paolo; Nobile, Maria; Crippa, Alessandro; Molteni, Massimo

2011-01-01

Kinematic recordings in a reach and drop task were compared between 12 preschool children with autism without mental retardation and 12 gender and age-matched normally developing children. Our aim was to investigate whether motor anomalies in autism may depend more on a planning ability dysfunction or on a motor control deficit. Planning and…

Bilirubin-Induced Neurological Dysfunction: A Clinico-Radiological-Neurophysiological Correlation in 30 Consecutive Children.

PubMed

van Toorn, Ronald; Brink, Philip; Smith, Johan; Ackermann, Christelle; Solomons, Regan

2016-12-01

The clinical expression of bilirubin-induced neurological dysfunction varies according to severity and location of the disease. Definitions have been proposed to describe different bilirubin-induced neurological dysfunction subtypes. Our objective was to describe the severity and clinico-radiological-neurophysiological correlation in 30 consecutive children with bilirubin-induced neurological dysfunction seen over a period of 5 years. Thirty children exposed to acute neonatal bilirubin encephalopathy were included in the study. The mean peak total serum bilirubin level was 625 μmol/L (range 480-900 μmol/L). Acoustic brainstem responses were abnormal in 73% (n = 22). Pallidal hyperintensity was observed on magnetic resonance imaging in 20 children. Peak total serum bilirubin levels correlated with motor severity (P = .03). Children with severe motor impairment were likely to manifest severe auditory neuropathy (P < .01). We found that in a resource-constrained setting, classical kernicterus was the most common bilirubin-induced neurological dysfunction subtype, and the majority of children had abnormal acoustic brainstem responses and magnetic resonance imaging. © The Author(s) 2016.

Silencing neuronal mutant androgen receptor in a mouse model of spinal and bulbar muscular atrophy.

PubMed

Sahashi, Kentaro; Katsuno, Masahisa; Hung, Gene; Adachi, Hiroaki; Kondo, Naohide; Nakatsuji, Hideaki; Tohnai, Genki; Iida, Madoka; Bennett, C Frank; Sobue, Gen

2015-11-01

Spinal and bulbar muscular atrophy (SBMA), an adult-onset neurodegenerative disease that affects males, results from a CAG triplet repeat/polyglutamine expansions in the androgen receptor (AR) gene. Patients develop progressive muscular weakness and atrophy, and no effective therapy is currently available. The tissue-specific pathogenesis, especially relative pathological contributions between degenerative motor neurons and muscles, remains inconclusive. Though peripheral pathology in skeletal muscle caused by toxic AR protein has been recently reported to play a pivotal role in the pathogenesis of SBMA using mouse models, the role of motor neuron degeneration in SBMA has not been rigorously investigated. Here, we exploited synthetic antisense oligonucleotides to inhibit the RNA levels of mutant AR in the central nervous system (CNS) and explore its therapeutic effects in our SBMA mouse model that harbors a mutant AR gene with 97 CAG expansions and characteristic SBMA-like neurogenic phenotypes. A single intracerebroventricular administration of the antisense oligonucleotides in the presymptomatic phase efficiently suppressed the mutant gene expression in the CNS, and delayed the onset and progression of motor dysfunction, improved body weight gain and survival with the amelioration of neuronal histopathology in motor units such as spinal motor neurons, neuromuscular junctions and skeletal muscle. These findings highlight the importance of the neurotoxicity of mutant AR protein in motor neurons as a therapeutic target. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

[Detection and specific studies in procedural learning difficulties].

PubMed

Magallón, S; Narbona, J

2009-02-27

The main disabilities in non-verbal learning disorder (NLD) are: the acquisition and automating of motor and cognitive processes, visual spatial integration, motor coordination, executive functions, difficulty in comprehension of the context, and social skills. AIMS. To review the research to date on NLD, and to discuss whether the term 'procedural learning disorder' (PLD) would be more suitable to refer to NLD. A considerable amount of research suggests a neurological correlate of PLD with dysfunctions in the 'posterior' attention system, or the right hemisphere, or the cerebellum. Even if it is said to be difficult the delimitation between NLD and other disorders or syndromes like Asperger syndrome, certain characteristics contribute to differential diagnosis. Intervention strategies for the PLD must lead to the development of motor automatisms and problem solving strategies, including social skills. The basic dysfunction in NLD affects to implicit learning of routines, automating of motor skills and cognitive strategies that spare conscious resources in daily behaviours. These limitations are partly due to a dysfunction in non-declarative procedural memory. Various dimensions of language are also involved: context comprehension, processing of the spatial and emotional indicators of verbal language, language inferences, prosody, organization of the inner speech, use of language and non-verbal communication; this is why the diagnostic label 'PLD' would be more appropriate, avoiding the euphemistic adjective 'non-verbal'.

Independence of motor unit recruitment and rate modulation during precision force control.

PubMed

Kamen, G; Du, D C

1999-01-01

The vertebrate motor system chiefly employs motor unit recruitment and rate coding to modulate muscle force output. In this paper, we studied how the recruitment of new motor units altered the firing rate of already-active motor units during precision force production in the first dorsal interosseous muscle. Six healthy adults performed linearly increasing isometric voluntary contractions while motor unit activity and force output were recorded. After motor unit discharges were identified, motor unit firing rates were calculated before and after the instances of new motor unit recruitment. Three procedures were applied to compute motor unit firing rate, including the mean of a fixed number of inter-spike intervals and the constant width weighted Hanning window filter method, as well as a modified boxcar technique. In contrast to previous reports, the analysis of the firing rates of over 200 motor units revealed that reduction of the active firing rates was not a common mechanism used to accommodate the twitch force produced by the recruitment of a new motor unit. Similarly, during de-recruitment there was no tendency for motor unit firing rates to increase immediately following the cessation of activity in other motor units. Considerable consistency in recruitment behavior was observed during repeated contractions. However, firing rates during repeated contractions demonstrated considerably more fluctuation. It is concluded that the neuromuscular system does not use short-term preferential motor unit disfacilitation to effect precise regulation of muscular force output.

Convergence of pattern generator outputs on a common mechanism of diaphragm motor unit recruitment

PubMed Central

Mantilla, Carlos B.; Seven, Yasin B.; Sieck, Gary C.

2014-01-01

Motor units are the final element of neuromotor control. In manner analogous to the organization of neuromotor control in other skeletal muscles, diaphragm motor units comprise phrenic motoneurons located in the cervical spinal cord that innervate the diaphragm muscle, the main inspiratory muscle in mammals. Diaphragm motor units play a primary role in sustaining ventilation, but are also active in other non-ventilatory behaviors, including coughing, sneezing, vomiting, defecation and parturition. Diaphragm muscle fibers comprise all fiber types. Thus, diaphragm motor units display substantial differences in contractile and fatigue properties, but importantly properties of the motoneuron and muscle fibers within a motor unit are matched. As in other skeletal muscles, diaphragm motor units are recruited in order such that motor units that display greater fatigue resistance are recruited earlier and more often than more fatigable motor units. The properties of the motor unit population are critical determinants of the function of a skeletal muscle across the range of possible motor tasks. Accordingly, fatigue-resistant motor units are sufficient to generate the forces necessary for ventilatory behaviors whereas more fatigable units are only activated during expulsive behaviors important for airway clearance. Neuromotor control of diaphragm motor units may reflect selective inputs from distinct pattern generators distributed according to the motor unit properties necessary to accomplish these different motor tasks. In contrast, widely-distributed inputs to phrenic motoneurons from various pattern generators (e.g., for breathing, coughing or vocalization) would dictate recruitment order based on intrinsic electrophysiological properties. PMID:24746055

Clinical features and dysfunctions of iron metabolism in Parkinson disease patients with hyper echogenicity in substantia nigra: a cross-sectional study.

PubMed

Yu, Shu-Yang; Cao, Chen-Jie; Zuo, Li-Jun; Chen, Ze-Jie; Lian, Teng-Hong; Wang, Fang; Hu, Yang; Piao, Ying-Shan; Li, Li-Xia; Guo, Peng; Liu, Li; Yu, Qiu-Jin; Wang, Rui-Dan; Chan, Piu; Chen, Sheng-di; Wang, Xiao-Min; Zhang, Wei

2018-01-17

Transcranial ultrasound is a useful tool for providing the evidences for the early diagnosis and differential diagnosis of Parkinson disease (PD). However, the relationship between hyper echogenicity in substantia nigra (SN) and clinical symptoms of PD patients remains unknown, and the role of dysfunction of iron metabolism on the pathogenesis of SN hyper echogenicity is unclear. PD patients was detected by transcranial sonography and divided into with no hyper echogenicity (PDSN-) group and with hyper echogenicity (PDSN+) group. Motor symptoms (MS) and non-motor symptoms (NMS) were evaluated, and the levels of iron and related proteins in serum and cerebrospinal fluid (CSF) were detected for PD patients. Data comparison between the two groups and correlation analyses were performed. PDSN+ group was significantly older, and had significantly older age of onset, more advanced Hohen-Yahr stage, higher SCOPA-AUT score and lower MoCA score than PDSN- group (P < 0.05). Compared with PDSN- group, the levels of transferrin and light-ferritin in serum and iron level in CSF were significantly elevated (P < 0.05), but ferroportin level in CSF was significantly decreased in PDSN+ group (P < 0.05). PD patients with hyper echogenicity in SN are older, at more advanced disease stage, have severer motor symptoms, and non-motor symptoms of cognitive impairment and autonomic dysfunction. Hyper echogenicity of SN in PD patients is related to dysfunction of iron metabolism, involving increased iron transport from peripheral system to central nervous system, reduction of intracellular iron release and excessive iron deposition in brain.

A role for Kalirin-7 in corticostriatal synaptic dysfunction in Huntington's disease

PubMed Central

Puigdellívol, Mar; Cherubini, Marta; Brito, Verónica; Giralt, Albert; Suelves, Núria; Ballesteros, Jesús; Zamora-Moratalla, Alfonsa; Martín, Eduardo D.; Eipper, Betty A.; Alberch, Jordi; Ginés, Silvia

2015-01-01

Cognitive dysfunction is an early clinical hallmark of Huntington's disease (HD) preceding the appearance of motor symptoms by several years. Neuronal dysfunction and altered corticostriatal connectivity have been postulated to be fundamental to explain these early disturbances. However, no treatments to attenuate cognitive changes have been successful: the reason may rely on the idea that the temporal sequence of pathological changes is as critical as the changes per se when new therapies are in development. To this aim, it becomes critical to use HD mouse models in which cognitive impairments appear prior to motor symptoms. In this study, we demonstrate procedural memory and motor learning deficits in two different HD mice and at ages preceding motor disturbances. These impairments are associated with altered corticostriatal long-term potentiation (LTP) and specific reduction of dendritic spine density and postsynaptic density (PSD)-95 and spinophilin-positive clusters in the cortex of HD mice. As a potential mechanism, we described an early decrease of Kalirin-7 (Kal7), a guanine-nucleotide exchange factor for Rho-like small GTPases critical to maintain excitatory synapse, in the cortex of HD mice. Supporting a role for Kal7 in HD synaptic deficits, exogenous expression of Kal7 restores the reduction of excitatory synapses in HD cortical cultures. Altogether, our results suggest that cortical dysfunction precedes striatal disturbances in HD and underlie early corticostriatal LTP and cognitive defects. Moreover, we identified diminished Kal7 as a key contributor to HD cortical alterations, placing Kal7 as a molecular target for future therapies aimed to restore corticostriatal function in HD. PMID:26464483

DOE Office of Scientific and Technical Information (OSTI.GOV)

Binukumar, BK; Gupta, Nidhi; Bal, Amanjit

Numerous epidemiological studies have shown an association between pesticide exposure and increased risk of developing Parkinson's diseases. Oxidative stress generated as a result of mitochondrial dysfunction has been implicated as an important factor in the etiology of Parkinson's disease. Previously, we reported that chronic dichlorvos exposure causes mitochondrial impairments and nigrostriatal neuronal death in rats. The present study was designed to test whether Coenzyme Q{sub 10} (CoQ{sub 10}) administration has any neuroprotective effect against dichlorvos mediated nigrostriatal neuronal death, {alpha}-synuclein aggregation, and motor dysfunction. Male albino rats were administered dichlorvos by subcutaneous injection at a dose of 2.5 mg/kg bodymore » weight over a period of 12 weeks. Results obtained there after showed that dichlorvos exposure leads to enhanced mitochondrial ROS production, {alpha}-synuclein aggregation, decreased dopamine and its metabolite levels resulting in nigrostriatal neurodegeneration. Pretreatment by Coenzyme Q{sub 10} (4.5 mg/kg ip for 12 weeks) to dichlorvos treated animals significantly attenuated the extent of nigrostriatal neuronal damage, in terms of decreased ROS production, increased dopamine and its metabolite levels, and restoration of motor dysfunction when compared to dichlorvos treated animals. Thus, the present study shows that Coenzyme Q{sub 10} administration may attenuate dichlorvos induced nigrostriatal neurodegeneration, {alpha}-synuclein aggregation and motor dysfunction by virtue of its antioxidant action. - Highlights: > CoQ{sub 10} administration attenuates dichlorvos induced nigrostriatal neurodegenaration. > CoQ{sub 10} pre treatment leads to preservation of TH-IR neurons. > CoQ{sub 10} may decrease oxidative damage and {alpha}-synuclin aggregation. > CoQ{sub 10} treatment enhances motor function and protects rats from catalepsy.« less

The processing of actions and action-words in amyotrophic lateral sclerosis patients.

PubMed

Papeo, Liuba; Cecchetto, Cinzia; Mazzon, Giulia; Granello, Giulia; Cattaruzza, Tatiana; Verriello, Lorenzo; Eleopra, Roberto; Rumiati, Raffaella I

2015-03-01

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with prime consequences on the motor function and concomitant cognitive changes, most frequently in the domain of executive functions. Moreover, poorer performance with action-verbs versus object-nouns has been reported in ALS patients, raising the hypothesis that the motor dysfunction deteriorates the semantic representation of actions. Using action-verbs and manipulable-object nouns sharing semantic relationship with the same motor representations, the verb-noun difference was assessed in a group of 21 ALS-patients with severely impaired motor behavior, and compared with a normal sample's performance. ALS-group performed better on nouns than verbs, both in production (action and object naming) and comprehension (word-picture matching). This observation implies that the interpretation of the verb-noun difference in ALS cannot be accounted by the relatedness of verbs to motor representations, but has to consider the role of other semantic and/or morpho-phonological dimensions that distinctively define the two grammatical classes. Moreover, this difference in the ALS-group was not greater than the noun-verb difference in the normal sample. The mental representation of actions also involves an executive-control component to organize, in logical/temporal order, the individual motor events (or sub-goals) that form a purposeful action. We assessed this ability with action sequencing tasks, requiring participants to re-construct a purposeful action from the scrambled presentation of its constitutive motor events, shown in the form of photographs or short sentences. In those tasks, ALS-group's performance was significantly poorer than controls'. Thus, the executive dysfunction manifested in the sequencing deficit -but not the selective verb deficit- appears as a consistent feature of the cognitive profile associated with ALS. We suggest that ALS can offer a valuable model to study the relationship between (frontal) motor centers and the executive-control machinery housed in the frontal brain, and the implications of executive dysfunctions in tasks such as action processing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simulation of motor unit recruitment and microvascular unit perfusion: spatial considerations.

PubMed

Fuglevand, A J; Segal, S S

1997-10-01

Muscle fiber activity is the principal stimulus for increasing capillary perfusion during exercise. The control elements of perfusion, i.e., microvascular units (MVUs), supply clusters of muscle fibers, whereas the control elements of contraction, i.e., motor units, are composed of fibers widely scattered throughout muscle. The purpose of this study was to examine how the discordant spatial domains of MVUs and motor units could influence the proportion of open capillaries (designated as perfusion) throughout a muscle cross section. A computer model simulated the locations of perfused MVUs in response to the activation of up to 100 motor units in a muscle with 40,000 fibers and a cross-sectional area of 100 mm2. The simulation increased contraction intensity by progressive recruitment of motor units. For each step of motor unit recruitment, the percentage of active fibers and the number of perfused MVUs were determined for several conditions: 1) motor unit fibers widely dispersed and motor unit territories randomly located (which approximates healthy human muscle), 2) regionalized motor unit territories, 3) reversed recruitment order of motor units, 4) densely clustered motor unit fibers, and 5) increased size but decreased number of motor units. The simulations indicated that the widespread dispersion of motor unit fibers facilitates complete capillary (MVU) perfusion of muscle at low levels of activity. The efficacy by which muscle fiber activity induced perfusion was reduced 7- to 14-fold under conditions that decreased the dispersion of active fibers, increased the size of motor units, or reversed the sequence of motor unit recruitment. Such conditions are similar to those that arise in neuromuscular disorders, with aging, or during electrical stimulation of muscle, respectively.

The Prevalence and Severity of Autonomic Dysfunction in Chronic Inflammatory Demyelinating Polyneuropathy

PubMed Central

Pasangulapati, Suresh Babu; Murthy, T. V.; Sivadasan, Ajith; Gideon, L. Rynjah; Prabhakar, A. T.; Sanjith, Aaron; Mathew, Vivek; Alexander, Mathew

2017-01-01

Introduction: In chronic inflammatory demyelinating polyneuropathy (CIDP), emphasis has been on motor disabilities, and autonomic dysfunction in these patients has not been addressed systematically. Materials and Methods: Autonomic function was prospectively analyzed in 38 patients with CIDP. Quantitative autonomic function testing was done using Finometer® PRO and severity of adrenergic and cardiovagal dysfunction graded according to composite autonomic severity score and sudomotor dysfunction assessed using sympathetic skin response. Results: Thirty-four (89%) patients had features of autonomic dysfunction. Thirty-three (86%) patients had cardiovagal dysfunction, 21 (55%) had adrenergic dysfunction, and 24 (63%) had sudomotor dysfunction. Autonomic dysfunction was mild to moderate in the majority (86%). Conclusions: Autonomic dysfunction in CIDP is underreported and potentially amenable to therapy. Our cohort had a high proportion of adrenergic dysfunction compared to previous studies. PMID:28904461

Convergence of pattern generator outputs on a common mechanism of diaphragm motor unit recruitment.

PubMed

Mantilla, Carlos B; Seven, Yasin B; Sieck, Gary C

2014-01-01

Motor units are the final element of neuromotor control. In manner analogous to the organization of neuromotor control in other skeletal muscles, diaphragm motor units comprise phrenic motoneurons located in the cervical spinal cord that innervate the diaphragm muscle, the main inspiratory muscle in mammals. Diaphragm motor units play a primary role in sustaining ventilation but are also active in other nonventilatory behaviors, including coughing, sneezing, vomiting, defecation, and parturition. Diaphragm muscle fibers comprise all fiber types. Thus, diaphragm motor units display substantial differences in contractile and fatigue properties, but importantly, properties of the motoneuron and muscle fibers within a motor unit are matched. As in other skeletal muscles, diaphragm motor units are recruited in order such that motor units that display greater fatigue resistance are recruited earlier and more often than more fatigable motor units. The properties of the motor unit population are critical determinants of the function of a skeletal muscle across the range of possible motor tasks. Accordingly, fatigue-resistant motor units are sufficient to generate the forces necessary for ventilatory behaviors, whereas more fatigable units are only activated during expulsive behaviors important for airway clearance. Neuromotor control of diaphragm motor units may reflect selective inputs from distinct pattern generators distributed according to the motor unit properties necessary to accomplish these different motor tasks. In contrast, widely distributed inputs to phrenic motoneurons from various pattern generators (e.g., for breathing, coughing, or vocalization) would dictate recruitment order based on intrinsic electrophysiological properties. © 2014 Elsevier B.V. All rights reserved.

Disease Mechanisms and Therapeutic Approaches in Spinal Muscular Atrophy

PubMed Central

Tisdale, Sarah

2015-01-01

Motor neuron diseases are neurological disorders characterized primarily by the degeneration of spinal motor neurons, skeletal muscle atrophy, and debilitating and often fatal motor dysfunction. Spinal muscular atrophy (SMA) is an autosomal-recessive motor neuron disease of high incidence and severity and the most common genetic cause of infant mortality. SMA is caused by homozygous mutations in the survival motor neuron 1 (SMN1) gene and retention of at least one copy of the hypomorphic gene paralog SMN2. Early studies established a loss-of-function disease mechanism involving ubiquitous SMN deficiency and suggested SMN upregulation as a possible therapeutic approach. In recent years, greater knowledge of the central role of SMN in RNA processing combined with deep characterization of animal models of SMA has significantly advanced our understanding of the cellular and molecular basis of the disease. SMA is emerging as an RNA disease not limited to motor neurons, but one that involves dysfunction of motor circuits that comprise multiple neuronal subpopulations and possibly other cell types. Advances in SMA research have also led to the development of several potential therapeutics shown to be effective in animal models of SMA that are now in clinical trials. These agents offer unprecedented promise for the treatment of this still incurable neurodegenerative disease. PMID:26063904

Garcinia kola seeds may prevent cognitive and motor dysfunctions in a type 1 diabetes mellitus rat model partly by mitigating neuroinflammation.

PubMed

Seke Etet, Paul F; Farahna, Mohammed; Satti, Gwiria M H; Bushara, Yahia M; El-Tahir, Ahmed; Hamza, Muaawia A; Osman, Sayed Y; Dibia, Ambrose C; Vecchio, Lorella

2017-04-15

Background We reported recently that extracts of seeds of Garcinia kola, a plant with established hypoglycemic properties, prevented the loss of inflammation-sensible neuronal populations like Purkinje cells in a rat model of type 1 diabetes mellitus (T1DM). Here, we assessed G. kola extract ability to prevent the early cognitive and motor dysfunctions observed in this model. Methods Rats made diabetic by single injection of streptozotocin were treated daily with either vehicle solution (diabetic control group), insulin, or G. kola extract from the first to the 6th week post-injection. Then, cognitive and motor functions were assessed using holeboard and vertical pole behavioral tests, and animals were sacrificed. Brains were dissected out, cut, and processed for Nissl staining and immunohistochemistry. Results Hyperglycemia (209.26 %), body weight loss (-12.37 %), and T1DM-like cognitive and motor dysfunctions revealed behavioral tests in diabetic control animals were not observed in insulin and extract-treated animals. Similar, expressions of inflammation markers tumor necrosis factor (TNF), iba1 (CD68), and Glial fibrillary acidic protein (GFAP), as well as decreases of neuronal density in regions involved in cognitive and motor functions (-49.56 % motor cortex, -33.24 % medial septal nucleus, -41.8 % /-37.34 % cerebellar Purkinje /granular cell layers) were observed in diabetic controls but not in animals treated with insulin or G. kola. Conclusions Our results indicate that T1DM-like functional alterations are mediated, at least partly, by neuroinflammation and neuronal loss in this model. The prevention of the development of such alterations by early treatment with G. kola confirms the neuroprotective properties of the plant and warrant further mechanistic studies, considering the potential for human disease.

Sitting Together And Reaching To Play (START-Play): Protocol for a Multisite Randomized Controlled Efficacy Trial on Intervention for Infants With Neuromotor Disorders.

PubMed

Harbourne, Regina T; Dusing, Stacey C; Lobo, Michele A; Westcott-McCoy, Sarah; Bovaird, James; Sheridan, Susan; Galloway, James C; Chang, Hui-Ju; Hsu, Lin-Ya; Koziol, Natalie; Marcinowski, Emily C; Babik, Iryna

2018-06-01

There is limited research examining the efficacy of early physical therapy on infants with neuromotor dysfunction. In addition, most early motor interventions have not been directly linked to learning, despite the clear association between motor activity and cognition during infancy. The aim of this project is to evaluate the efficacy of Sitting Together And Reaching To Play (START-Play), an intervention designed to target sitting, reaching, and motor-based problem solving to advance global development in infants with motor delays or neuromotor dysfunction. This study is a longitudinal multisite randomized controlled trial. Infants in the START-Play group are compared to infants receiving usual care in early intervention (EI). The research takes place in homes in Pennsylvania, Delaware, Washington, and Virginia. There will be 140 infants with neuromotor dysfunction participating, beginning between 7 to 16 months of age. Infants will have motor delays and emerging sitting skill. START-Play provides individualized twice-weekly home intervention for 12 weeks with families to enhance cognition through sitting, reaching, and problem-solving activities for infants. Ten interventionists provide the intervention, with each child assigned 1 therapist. The primary outcome measure is the Bayley III Scales of Infant Development. Secondary measures include change in the Early Problem Solving Indicator, change in the Gross Motor Function Measure, and change in the type and duration of toy contacts during reaching. Additional measures include sitting posture control and parent-child interaction. Limitations include variability in usual EI care and the lack of blinding for interventionists and families. This study describes usual care in EI across 4 US regions and compares outcomes of the START-Play intervention to usual care.

Phrenic Motor Unit Recruitment during Ventilatory and Non-Ventilatory Behaviors

PubMed Central

Mantilla, Carlos B.; Sieck, Gary C.

2011-01-01

Phrenic motoneurons are located in the cervical spinal cord and innervate the diaphragm muscle, the main inspiratory muscle in mammals. Similar to other skeletal muscles, phrenic motoneurons and diaphragm muscle fibers form motor units which are the final element of neuromotor control. In addition to their role in sustaining ventilation, phrenic motor units are active in other non-ventilatory behaviors important for airway clearance such as coughing or sneezing. Diaphragm muscle fibers comprise all fiber types and are commonly classified based on expression of contractile proteins including myosin heavy chain isoforms. Although there are differences in contractile and fatigue properties across motor units, there is a matching of properties for the motor neuron and muscle fibers within a motor unit. Motor units are generally recruited in order such that fatigue-resistant motor units are recruited earlier and more often than more fatigable motor units. Thus, in sustaining ventilation, fatigue-resistant motor units are likely required. Based on a series of studies in cats, hamsters and rats, an orderly model of motor unit recruitment was proposed that takes into consideration the maximum forces generated by single type-identified diaphragm muscle fibers as well as the proportion of the different motor unit types. Using this model, eupnea can be accomplished by activation of only slow-twitch diaphragm motor units and only a subset of fast-twitch, fatigue-resistant units. Activation of fast-twitch fatigable motor units only becomes necessary when accomplishing tasks that require greater force generation by the diaphragm muscle, e.g., sneezing and coughing. PMID:21763470

Phrenic motor unit recruitment during ventilatory and non-ventilatory behaviors.

PubMed

Mantilla, Carlos B; Sieck, Gary C

2011-10-15

Phrenic motoneurons are located in the cervical spinal cord and innervate the diaphragm muscle, the main inspiratory muscle in mammals. Similar to other skeletal muscles, phrenic motoneurons and diaphragm muscle fibers form motor units which are the final element of neuromotor control. In addition to their role in sustaining ventilation, phrenic motor units are active in other non-ventilatory behaviors important for airway clearance such as coughing or sneezing. Diaphragm muscle fibers comprise all fiber types and are commonly classified based on expression of contractile proteins including myosin heavy chain isoforms. Although there are differences in contractile and fatigue properties across motor units, there is a matching of properties for the motor neuron and muscle fibers within a motor unit. Motor units are generally recruited in order such that fatigue-resistant motor units are recruited earlier and more often than more fatigable motor units. Thus, in sustaining ventilation, fatigue-resistant motor units are likely required. Based on a series of studies in cats, hamsters and rats, an orderly model of motor unit recruitment was proposed that takes into consideration the maximum forces generated by single type-identified diaphragm muscle fibers as well as the proportion of the different motor unit types. Using this model, eupnea can be accomplished by activation of only slow-twitch diaphragm motor units and only a subset of fast-twitch, fatigue-resistant units. Activation of fast-twitch fatigable motor units only becomes necessary when accomplishing tasks that require greater force generation by the diaphragm muscle, e.g., sneezing and coughing. Copyright © 2011 Elsevier B.V. All rights reserved.

Motor unit recruitment in human biceps brachii during sustained voluntary contractions.

PubMed

Riley, Zachary A; Maerz, Adam H; Litsey, Jane C; Enoka, Roger M

2008-04-15

The purpose of the study was to examine the influence of the difference between the recruitment threshold of a motor unit and the target force of the sustained contraction on the discharge of the motor unit at recruitment. The discharge characteristics of 53 motor units in biceps brachii were recorded after being recruited during a sustained contraction. Some motor units (n = 22) discharged action potentials tonically after being recruited, whereas others (n = 31) discharged intermittent trains of action potentials. The two groups of motor units were distinguished by the difference between the recruitment threshold of the motor unit and the target force for the sustained contraction: tonic, 5.9 +/- 2.5%; intermittent, 10.7 +/- 2.9%. Discharge rate for the tonic units decreased progressively (13.9 +/- 2.7 to 11.7 +/- 2.6 pulses s(-1); P = 0.04) during the 99 +/- 111 s contraction. Train rate, train duration and average discharge rate for the intermittent motor units did not change across 211 +/- 153 s of intermittent discharge. The initial discharge rate at recruitment during the sustained contraction was lower for the intermittent motor units (11.0 +/- 3.3 pulses s(-1)) than the tonic motor units (13.7 +/- 3.3 pulses s(-1); P = 0.005), and the coefficient of variation for interspike interval was higher for the intermittent motor units (34.6 +/- 12.3%) than the tonic motor units (21.2 +/- 9.4%) at recruitment (P = 0.001) and remained elevated for discharge duration (34.6 +/- 9.2% versus 19.1 +/- 11.7%, P < 0.001). In an additional experiment, 12 motor units were recorded at two different target forces below recruitment threshold (5.7 +/- 1.9% and 10.5 +/- 2.4%). Each motor unit exhibited the two discharge patterns (tonic and intermittent) as observed for the 53 motor units. The results suggest that newly recruited motor units with recruitment thresholds closer to the target force experienced less synaptic noise at the time of recruitment that resulted in them discharging action potentials at more regular and greater rates than motor units with recruitment thresholds further from the target force.

Transcriptomics of aged Drosophila motor neurons reveals a matrix metalloproteinase that impairs motor function.

PubMed

Azpurua, Jorge; Mahoney, Rebekah E; Eaton, Benjamin A

2018-04-01

The neuromuscular junction (NMJ) is responsible for transforming nervous system signals into motor behavior and locomotion. In the fruit fly Drosophila melanogaster, an age-dependent decline in motor function occurs, analogous to the decline experienced in mice, humans, and other mammals. The molecular and cellular underpinnings of this decline are still poorly understood. By specifically profiling the transcriptome of Drosophila motor neurons across age using custom microarrays, we found that the expression of the matrix metalloproteinase 1 (dMMP1) gene reproducibly increased in motor neurons in an age-dependent manner. Modulation of physiological aging also altered the rate of dMMP1 expression, validating dMMP1 expression as a bona fide aging biomarker for motor neurons. Temporally controlled overexpression of dMMP1 specifically in motor neurons was sufficient to induce deficits in climbing behavior and cause a decrease in neurotransmitter release at neuromuscular synapses. These deficits were reversible if the dMMP1 expression was shut off again immediately after the onset of motor dysfunction. Additionally, repression of dMMP1 enzymatic activity via overexpression of a tissue inhibitor of metalloproteinases delayed the onset of age-dependent motor dysfunction. MMPs are required for proper tissue architecture during development. Our results support the idea that matrix metalloproteinase 1 is acting as a downstream effector of antagonistic pleiotropy in motor neurons and is necessary for proper development, but deleterious when reactivated at an advanced age. © 2018 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Ghrelin enhancer, rikkunshito, improves postprandial gastric motor dysfunction in an experimental stress model.

PubMed

Harada, Y; Ro, S; Ochiai, M; Hayashi, K; Hosomi, E; Fujitsuka, N; Hattori, T; Yakabi, K

2015-08-01

Functional dyspepsia (FD) is one of the most common disorders of gastrointestinal (GI) diseases. However, no curable treatment is available for FD because the detailed mechanism of GI dysfunction in stressed conditions remains unclear. We aimed to clarify the association between endogenous acylated ghrelin signaling and gastric motor dysfunction and explore the possibility of a drug with ghrelin signal-enhancing action for FD treatment. Solid gastric emptying (GE) and plasma acylated ghrelin levels were evaluated in an urocortin1 (UCN1) -induced stress model. To clarify the role of acylated ghrelin on GI dysfunction in the model, exogenous acylated ghrelin, an endogenous ghrelin enhancer, rikkunshito, or an α2 -adrenergic receptor (AR) antagonist was administered. Postprandial motor function was investigated using a strain gauge force transducer in a free-moving condition. Exogenous acylated ghrelin supplementation restored UCN1-induced delayed GE. Alpha2 -AR antagonist and rikkunshito inhibited the reduction in plasma acylated ghrelin and GE in the stress model. The action of rikkunshito on delayed GE was blocked by co-administration of the ghrelin receptor antagonist. UCN1 decreased the amplitude of contraction in the antrum while increasing it in the duodenum. The motility index of the antrum but not the duodenum was significantly reduced by UCN1 treatment, which was improved by acylated ghrelin or rikkunshito. The UCN1-induced gastric motility dysfunction was mediated by abnormal acylated ghrelin dynamics. Supplementation of exogenous acylated ghrelin or enhancement of endogenous acylated ghrelin secretion by rikkunshito may be effective in treating functional GI disorders. © 2015 The Authors. Neurogastroenterology & Motility Published by John Wiley & Sons Ltd.

Segmentation of the mouse fourth deep lumbrical muscle connectome reveals concentric organisation of motor units

PubMed Central

Hirst, Theodore C; Ribchester, Richard R

2013-01-01

Connectomic analysis of the nervous system aims to discover and establish principles that underpin normal and abnormal neural connectivity and function. Here we performed image analysis of motor unit connectivity in the fourth deep lumbrical muscle (4DL) of mice, using transgenic expression of fluorescent protein in motor neurones as a morphological reporter. We developed a method that accelerated segmentation of confocal image projections of 4DL motor units, by applying high resolution (63×, 1.4 NA objective) imaging or deconvolution only where either proved necessary, in order to resolve axon crossings that produced ambiguities in the correct assignment of axon terminals to identified motor units imaged at lower optical resolution (40×, 1.3 NA). The 4DL muscles contained between 4 and 9 motor units and motor unit sizes ranged in distribution from 3 to 111 motor nerve terminals per unit. Several structural properties of the motor units were consistent with those reported in other muscles, including suboptimal wiring length and distribution of motor unit size. Surprisingly, however, small motor units were confined to a region of the muscle near the nerve entry point, whereas their larger counterparts were progressively more widely dispersed, suggesting a previously unrecognised form of segregated motor innervation in this muscle. We also found small but significant differences in variance of motor endplate length in motor units, which correlated weakly with their motor unit size. Thus, our connectomic analysis has revealed a pattern of concentric innervation that may perhaps also exist in other, cylindrical muscles that have not previously been thought to show segregated motor unit organisation. This organisation may be the outcome of competition during postnatal development based on intrinsic neuronal differences in synaptic size or synaptic strength that generates a territorial hierarchy in motor unit size and disposition. PMID:23940381

Motor and Executive Function Profiles in Adult Residents Environmentally Exposed to Manganese

EPA Science Inventory

Objective: Exposure to elevated levels of manganese (Mn) may be associated with tremor, motor and executive dysfunction (EF), clinically resembling Parkinson’s disease (PD). PD research has identified tremor-dominant (TD) and non-tremor dominant (NTD) profiles. NTD PD pres...

HO-1 induction in motor cortex and intestinal dysfunction in TDP-43 A315T transgenic mice.

PubMed

Guo, Yansu; Wang, Qian; Zhang, Kunxi; An, Ting; Shi, Pengxiao; Li, Zhongyao; Duan, Weisong; Li, Chunyan

2012-06-15

TAR DNA-binding protein 43 (TDP-43) has been found to be related to the pathogenesis of amyotrophic lateral sclerosis (ALS). TDP-43 A315T transgenic mice develop degeneration of specific motor neurons, and accumulation of ubiquitinated proteins has been observed in the pyramidal cells of motor cortex of these mice. In this study, we found stress-responsive HO-1 induction and no autophagic alteration in motor cortex of TDP-43 A315T transgenic mice. Glial activation, especially astrocytic proliferation, occurred in cortical layer 5 and sub-meningeal region. Interestingly, we noticed that progressively thinned colon, swollen small intestine and reduced food intake, rather than severe muscle weakness, contributed to the death of TDP-43 A315T transgenic mice. Increased TDP-43 accumulation in the myenteric nerve plexus and increased thickness of muscular layer of colon were related to the intestinal dysfunction. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of rosmarinic acid in motor dysfunction and life span in a mouse model of familial amyotrophic lateral sclerosis.

PubMed

Shimojo, Yosuke; Kosaka, Kunio; Noda, Yoshihiro; Shimizu, Takahiko; Shirasawa, Takuji

2010-03-01

Amyotrophic lateral sclerosis (ALS) is a late-onset progressive neurodegenerative disease affecting motor neurons. About 2% of patients with the disease are associated with mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1). The purpose of this study is to assess the effect of rosemary extract and its major constituents, rosmarinic acid (RA) and carnosic acid (CA), in human SOD1 G93A transgenic mice, which are well-established mouse models for ALS. The present study demonstrates that intraperitoneal administration of rosemary extract or RA from the presymptomatic stage significantly delayed motor dysfunction in paw grip endurance tests, attenuated the degeneration of motor neurons, and extended the life span of ALS model mice. In addition, RA administration significantly improved the clinical score and suppressed body weight loss compared with a vehicle-treated group. In conclusion, this study provides the first report that rosemary extract and, especially, RA have preventive effects in the mouse model of ALS.

Visuo-motor and cognitive procedural learning in children with basal ganglia pathology.

PubMed

Mayor-Dubois, C; Maeder, P; Zesiger, P; Roulet-Perez, E

2010-06-01

We investigated procedural learning in 18 children with basal ganglia (BG) lesions or dysfunctions of various aetiologies, using a visuo-motor learning test, the Serial Reaction Time (SRT) task, and a cognitive learning test, the Probabilistic Classification Learning (PCL) task. We compared patients with early (<1 year old, n=9), later onset (>6 years old, n=7) or progressive disorder (idiopathic dystonia, n=2). All patients showed deficits in both visuo-motor and cognitive domains, except those with idiopathic dystonia, who displayed preserved classification learning skills. Impairments seem to be independent from the age of onset of pathology. As far as we know, this study is the first to investigate motor and cognitive procedural learning in children with BG damage. Procedural impairments were documented whatever the aetiology of the BG damage/dysfunction and time of pathology onset, thus supporting the claim of very early skill learning development and lack of plasticity in case of damage. Copyright 2010 Elsevier Ltd. All rights reserved.

Myopathic involvement and mitochondrial pathology in Kennedy disease and in other motor neuron diseases.

PubMed

Orsucci, D; Rocchi, A; Caldarazzo Ienco, E; Alì, G; LoGerfo, A; Petrozzi, L; Scarpelli, M; Filosto, M; Carlesi, C; Siciliano, G; Bonuccelli, U; Mancuso, M

2014-01-01

Kennedy disease (spinal and bulbar muscular atrophy, or SBMA) is a motor neuron disease caused by a CAG expansion in the androgen-receptor (AR) gene. Increasing evidence shows that SBMA may have a primary myopathic component and that mitochondrial dysfunction may have some role in the pathogenesis of this disease. In this article, we review the role of mitochondrial dysfunction and of the mitochondrial genome (mtDNA) in SBMA, and we present the illustrative case of a patient who presented with increased CK levels and exercise intolerance. Molecular analysis led to definitive diagnosis of SBMA, whereas muscle biopsy showed a mixed myopathic and neurogenic process with "mitochondrial features" and multiple mtDNA deletions, supporting some role of mitochondria in the pathogenesis of the myopathic component of Kennedy disease. Furthermore, we briefly review the role of mitochondrial dysfunction in two other motor neuron diseases (namely spinal muscular atrophy and amyotrophic lateral sclerosis). Most likely, in most cases mtDNA does not play a primary role and it is involved subsequently. MtDNA deletions may contribute to the neurodegenerative process, but the exact mechanisms are still unclear. It will be important to develop a better understanding of the role of mitochondrial dysfunction in motoneuron diseases, since it may lead to the development of more effective strategies for the treatment of this devastating disorder.

Selective disruption of acetylcholine synthesis in subsets of motor neurons: a new model of late-onset motor neuron disease.

PubMed

Lecomte, Marie-José; Bertolus, Chloé; Santamaria, Julie; Bauchet, Anne-Laure; Herbin, Marc; Saurini, Françoise; Misawa, Hidemi; Maisonobe, Thierry; Pradat, Pierre-François; Nosten-Bertrand, Marika; Mallet, Jacques; Berrard, Sylvie

2014-05-01

Motor neuron diseases are characterized by the selective chronic dysfunction of a subset of motor neurons and the subsequent impairment of neuromuscular function. To reproduce in the mouse these hallmarks of diseases affecting motor neurons, we generated a mouse line in which ~40% of motor neurons in the spinal cord and the brainstem become unable to sustain neuromuscular transmission. These mice were obtained by conditional knockout of the gene encoding choline acetyltransferase (ChAT), the biosynthetic enzyme for acetylcholine. The mutant mice are viable and spontaneously display abnormal phenotypes that worsen with age including hunched back, reduced lifespan, weight loss, as well as striking deficits in muscle strength and motor function. This slowly progressive neuromuscular dysfunction is accompanied by muscle fiber histopathological features characteristic of neurogenic diseases. Unexpectedly, most changes appeared with a 6-month delay relative to the onset of reduction in ChAT levels, suggesting that compensatory mechanisms preserve muscular function for several months and then are overwhelmed. Deterioration of mouse phenotype after ChAT gene disruption is a specific aging process reminiscent of human pathological situations, particularly among survivors of paralytic poliomyelitis. These mutant mice may represent an invaluable tool to determine the sequence of events that follow the loss of function of a motor neuron subset as the disease progresses, and to evaluate therapeutic strategies. They also offer the opportunity to explore fundamental issues of motor neuron biology. Copyright © 2014 Elsevier Inc. All rights reserved.

Training adaptations in the behavior of human motor units.

PubMed

Duchateau, Jacques; Semmler, John G; Enoka, Roger M

2006-12-01

The purpose of this brief review is to examine the neural adaptations associated with training, by focusing on the behavior of single motor units. The review synthesizes current understanding on motor unit recruitment and rate coding during voluntary contractions, briefly describes the techniques used to record motor unit activity, and then evaluates the adaptations that have been observed in motor unit activity during maximal and submaximal contractions. Relatively few studies have directly compared motor unit behavior before and after training. Although some studies suggest that the voluntary activation of muscle can increase slightly with strength training, it is not known how the discharge of motor units changes to produce this increase in activation. The evidence indicates that the increase is not attributable to changes in motor unit synchronization. It has been demonstrated, however, that training can increase both the rate of torque development and the discharge rate of motor units. Furthermore, both strength training and practice of a force-matching task can evoke adaptations in the discharge characteristics of motor units. Because the variability in discharge rate has a significant influence on the fluctuations in force during submaximal contractions, the changes produced with training can influence motor performance during activities of daily living. Little is known, however, about the relative contributions of the descending drive, afferent feedback, spinal circuitry, and motor neuron properties to the observed adaptations in motor unit activity.

Oromotor Dysfunction and Communication Impairments in Children with Cerebral Palsy: A Register Study

ERIC Educational Resources Information Center

Parkes, Jackie; Hill, Nan; Platt, Mary Jane; Donnelly, Caroline

2010-01-01

Aim: To report the prevalence, clinical associations, and trends over time of oromotor dysfunction and communication impairments in children with cerebral palsy (CP). Method: Multiple sources of ascertainment were used and children followed up with a standardized assessment including motor speech problems, swallowing/chewing difficulties,…

Circadian dysfunction may be a key component of the non-motor symptoms of Parkinson’s disease: insights from a transgenic mouse model

PubMed Central

Willison, L. David; Kudo, Takashi; Loh, Dawn H.; Kuljis, Dika; Colwell, Christopher S.

2014-01-01

Sleep disorders are nearly ubiquitous among patients with Parkinson’s disease (PD), and they manifest early in the disease process. While there are a number of possible mechanisms underlying these sleep disturbances, a primary dysfunction of the circadian system should be considered as a contributing factor. Our laboratory’s behavioral phenotyping of a well-validated transgenic mouse model of PD reveals that the electrical activity of neurons within the master pacemaker of the circadian system, the suprachiasmatic nuclei (SCN), is already disrupted at the onset of motor symptoms, although the core features of the intrinsic molecular oscillations in the SCN remain functional. Our observations suggest that the fundamental circadian deficit in these mice lies in the signaling output from the SCN, which may be caused by known mechanisms in PD etiology: oxidative stress and mitochondrial disruption. Disruption of the circadian system is expected to have pervasive effects throughout the body and may itself lead to neurological and cardiovascular disorders. In fact, there is much overlap in the non-motor symptoms experienced by PD patients and in the consequences of circadian disruption. This raises the possibility that the sleep and circadian dysfunction experienced by PD patients may not merely be a subsidiary of the motor symptoms, but an integral part of the disease. Furthermore, we speculate that circadian dysfunction can even accelerate the pathology underlying PD. If these hypotheses are correct, more aggressive treatment of the circadian misalignment and sleep disruptions in PD patients early in the pathogenesis of the disease may be powerful positive modulators of disease progression and patient quality of life. PMID:23353924

Hierarchy of Dysfunction Related to Dressing Performance in Stroke Patients: A Path Analysis Study.

PubMed

Fujita, Takaaki; Nagayama, Hirofumi; Sato, Atsushi; Yamamoto, Yuichi; Yamane, Kazuhiro; Otsuki, Koji; Tsuchiya, Kenji; Tozato, Fusae

2016-01-01

Previous reports indicated that various dysfunctions caused by stroke affect the level of independence in dressing. These dysfunctions can be hierarchical, and these effects on dressing performance can be complicated in stroke patients. However, there are no published reports focusing on the hierarchical structure of the relationships between the activities of daily living and balance function, motor and sensory functions of the affected lower limb, strength of the abdominal muscles and knee extension on the unaffected side, and visuospatial deficits. The purpose of this study was to elucidate the hierarchical and causal relationships between dressing performance and these dysfunctions in stroke patients. This retrospective study included 104 first-time stroke patients. The causal relationship between the dressing performance and age, time post stroke, balance function, motor and sensory functions of the affected lower limb, strength of the abdominal muscles and knee extension on the unaffected side, and visuospatial deficits were examined using path analysis. A hypothetical path model was created based on previous studies, and the goodness of fit between the data and model were verified. A modified path model was created that achieved an almost perfect fit to the data. Balance function and abdominal muscle strength have direct effects on dressing performance, with standardized direct effect estimates of 0.78 and 0.15, respectively. Age, motor and sensory functions of the affected lower limb, and strength of abdominal muscle and knee extension on the unaffected side have indirect effects on dressing by influencing balance function. Our results suggest that dressing performance depends strongly on balance function, and it is mainly influenced by the motor function of the affected lower limb.

Motor unit recruitment for dynamic tasks: current understanding and future directions.

PubMed

Hodson-Tole, Emma F; Wakeling, James M

2009-01-01

Skeletal muscle contains many muscle fibres that are functionally grouped into motor units. For any motor task there are many possible combinations of motor units that could be recruited and it has been proposed that a simple rule, the 'size principle', governs the selection of motor units recruited for different contractions. Motor units can be characterised by their different contractile, energetic and fatigue properties and it is important that the selection of motor units recruited for given movements allows units with the appropriate properties to be activated. Here we review what is currently understood about motor unit recruitment patterns, and assess how different recruitment patterns are more or less appropriate for different movement tasks. During natural movements the motor unit recruitment patterns vary (not always holding to the size principle) and it is proposed that motor unit recruitment is likely related to the mechanical function of the muscles. Many factors such as mechanics, sensory feedback, and central control influence recruitment patterns and consequently an integrative approach (rather than reductionist) is required to understand how recruitment is controlled during different movement tasks. Currently, the best way to achieve this is through in vivo studies that relate recruitment to mechanics and behaviour. Various methods for determining motor unit recruitment patterns are discussed, in particular the recent wavelet-analysis approaches that have allowed motor unit recruitment to be assessed during natural movements. Directions for future studies into motor recruitment within and between functional task groups and muscle compartments are suggested.

Cognitive and motor shifting aptitude disorder in Parkinson's disease.

PubMed Central

Cools, A R; van den Bercken, J H; Horstink, M W; van Spaendonck, K P; Berger, H J

1984-01-01

Eighteen patients suffering from Parkinson's disease and nineteen control subjects, who were matched for age and intelligence, were compared in tests measuring "shifting aptitude" at cognitive and motor levels (word production, sorting blocks or animals, and finger pushing sequences). It was found that Parkinson patients produced fewer different names of animals and professions in one minute than control subjects, needed more trials for detecting a shift in a sorting criterion, and produced fewer finger responses in a change of pushing sequence than control subjects. These results are interpreted as reflecting a central programming deficit that manifests itself in verbal, figural and motor modalities, that is, a diminished "shifting aptitude" characteristic of patients with dysfunctioning basal ganglia. The results are discussed in relation to changes of behaviour organisations in animals with dysfunctioning basal ganglia. PMID:6736974

[Pure trigeminal motor neuropathy presenting with temporo-mandibular joint dysfunction in a patient with HIV and HCV infections].

PubMed

Anheim, M; Echaniz-Laguna, A; Rey, D; Tranchant, C

2006-01-01

Pure trigeminal motor neuropathy (PTMN) is a rarely described condition. We report the case of a 41-year-old woman infected with the human immunodeficiency virus (HIV1) and hepatitis C virus who presented with weakness of left temporalis and masseter muscles and painful left temporomandibular joint dysfunction (TMD) a few months after cerebral toxoplasmosis revealing acquired immunodeficiency syndrome (AIDS). Magnetic resonance imaging revealed severe wasting and fat replacement of the left temporalis, pterygoid and masseter muscles and showed neither abnormalities in the left motor nucleus of the trigeminal nerve nor compression of the left trigeminal nerve. Electromyographic examination gave evidence of denervation in the left temporalis, masseter and pterygoid muscles and blink reflex studies were normal, confirming the diagnosis of PTMN which was probably secondary to HIV and HCV co-infection.

Altered cortico-basal ganglia motor pathways reflect reduced volitional motor activity in schizophrenia.

PubMed

Bracht, Tobias; Schnell, Susanne; Federspiel, Andrea; Razavi, Nadja; Horn, Helge; Strik, Werner; Wiest, Roland; Dierks, Thomas; Müller, Thomas J; Walther, Sebastian

2013-02-01

Little is known about the neurobiology of hypokinesia in schizophrenia. Therefore, the aim of this study was to investigate alterations of white matter motor pathways in schizophrenia and to relate our findings to objectively measured motor activity. We examined 21 schizophrenia patients and 21 healthy controls using diffusion tensor imaging and actigraphy. We applied a probabilistic fibre tracking approach to investigate pathways connecting the dorsolateral prefrontal cortex (dlPFC), the rostral anterior cingulate cortex (rACC), the pre-supplementary motor area (pre-SMA), the supplementary motor area proper (SMA-proper), the primary motor cortex (M1), the caudate nucleus, the striatum, the pallidum and the thalamus. Schizophrenia patients had lower activity levels than controls. In schizophrenia we found higher probability indices forming part of a bundle of interest (PIBI) in pathways connecting rACC, pre-SMA and SMA-proper as well as in pathways connecting M1 and pre-SMA with caudate nucleus, putamen, pallidum and thalamus and a reduced spatial extension of motor pathways in schizophrenia. There was a positive correlation between PIBI and activity level in the right pre-SMA-pallidum and the left M1-thalamus connection in healthy controls, and in the left pre-SMA-SMA-proper pathway in schizophrenia. Our results point to reduced volitional motor activity and altered motor pathway organisation in schizophrenia. The identified associations between the amount of movement and structural connectivity of motor pathways suggest dysfunction of cortico-basal ganglia pathways in the pathophysiology of hypokinesia in schizophrenia. Schizophrenia patients may use cortical pathways involving the supplementary motor area to compensate for basal ganglia dysfunction. Copyright © 2012 Elsevier B.V. All rights reserved.

Twenty-four-hour motor activity in human infants with and without iron deficiency anemia.

PubMed

Angulo-Kinzler, R M; Peirano, P; Lin, E; Algarin, C; Garrido, M; Lozoff, B

2002-12-01

Iron deficiency anemia (IDA) is a very common nutritional problem that alters motor activity. The aim of this study was to compare 24-h motor activity in the home in healthy 6-month-old infants with and without IDA. Activity was assessed via actigraphs on the leg during 24 continuous hours in 17 Chilean infants with IDA and 18 with normal hemoglobin levels. All infants were given oral iron, and activity was reassessed at 12 and 18 months. The frequency of movement units per minute was determined for each waking/sleep state during the day and night, and the duration of each state was computed. At 6 months of age, there were no differences between anemic and nonanemic infants in time per state. However, infants with IDA showed an overall increase in motor activity compared to controls. These differences were no longer observed at 12 and 18 months of age. Increased activity during the period of IDA raises the issue of a shared underlying mechanism with restless legs syndrome, a sensorimotor dysfunction where iron deficiency increases the severity of the symptoms and iron supplementation ameliorates them. Due to previous findings of decreased motor activity in the laboratory at 12 months during the waking time surrounding an afternoon nap, we also compared those data to a nap in the home. Infants with IDA were less active in the laboratory than in the home. The home versus laboratory results suggest that contextual factors affect the motor activity of IDA infants to a larger extent than controls.

Recruitment of rat diaphragm motor units across motor behaviors with different levels of diaphragm activation.

PubMed

Seven, Yasin B; Mantilla, Carlos B; Sieck, Gary C

2014-12-01

Phrenic motor neurons are recruited across a range of motor behaviors to generate varying levels of diaphragm muscle (DIAm) force. We hypothesized that DIAm motor units are recruited in a fixed order across a range of motor behaviors of varying force levels, consistent with the Henneman Size Principle. Single motor unit action potentials and compound DIAm EMG activities were recorded in anesthetized, neurally intact rats across different motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), deep breaths, sustained airway occlusion, and sneezing. Central drive [estimated by root-mean-squared (RMS) EMG value 75 ms after the onset of EMG activity (RMS75)], recruitment delay, and onset discharge frequencies were similar during eupnea and hypoxia-hypercapnia. Compared with eupnea, central drive increased (∼25%) during deep breaths, and motor units were recruited ∼12 ms earlier (P < 0.01). During airway occlusion, central drive was ∼3 times greater, motor units were recruited ∼30 ms earlier (P < 0.01), and motor unit onset discharge frequencies were significantly higher (P < 0.01). Recruitment order of motor unit pairs observed during eupnea was maintained for 98%, 87%, and 84% of the same pairs recorded during hypoxia-hypercapnia, deep breaths, and airway occlusion, respectively. Reversals in motor unit recruitment order were observed primarily if motor unit pairs were recruited <20 ms apart. These results are consistent with DIAm motor unit recruitment order being determined primarily by the intrinsic size-dependent electrophysiological properties of phrenic motor neurons. Copyright © 2014 the American Physiological Society.

Recruitment of rat diaphragm motor units across motor behaviors with different levels of diaphragm activation

PubMed Central

Seven, Yasin B.; Mantilla, Carlos B.

2014-01-01

Phrenic motor neurons are recruited across a range of motor behaviors to generate varying levels of diaphragm muscle (DIAm) force. We hypothesized that DIAm motor units are recruited in a fixed order across a range of motor behaviors of varying force levels, consistent with the Henneman Size Principle. Single motor unit action potentials and compound DIAm EMG activities were recorded in anesthetized, neurally intact rats across different motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), deep breaths, sustained airway occlusion, and sneezing. Central drive [estimated by root-mean-squared (RMS) EMG value 75 ms after the onset of EMG activity (RMS75)], recruitment delay, and onset discharge frequencies were similar during eupnea and hypoxia-hypercapnia. Compared with eupnea, central drive increased (∼25%) during deep breaths, and motor units were recruited ∼12 ms earlier (P < 0.01). During airway occlusion, central drive was ∼3 times greater, motor units were recruited ∼30 ms earlier (P < 0.01), and motor unit onset discharge frequencies were significantly higher (P < 0.01). Recruitment order of motor unit pairs observed during eupnea was maintained for 98%, 87%, and 84% of the same pairs recorded during hypoxia-hypercapnia, deep breaths, and airway occlusion, respectively. Reversals in motor unit recruitment order were observed primarily if motor unit pairs were recruited <20 ms apart. These results are consistent with DIAm motor unit recruitment order being determined primarily by the intrinsic size-dependent electrophysiological properties of phrenic motor neurons. PMID:25257864

The compensatory interaction between motor unit firing behavior and muscle force during fatigue

PubMed Central

De Luca, Carlo J.; Kline, Joshua C.

2016-01-01

Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. PMID:27385798

The compensatory interaction between motor unit firing behavior and muscle force during fatigue.

PubMed

Contessa, Paola; De Luca, Carlo J; Kline, Joshua C

2016-10-01

Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. Copyright © 2016 the American Physiological Society.

Substantiation of Structure of Adaptive Control Systems for Motor Units

NASA Astrophysics Data System (ADS)

Ovsyannikov, S. I.

2018-05-01

The article describes the development of new electronic control systems, in particular motor units, for small-sized agricultural equipment. Based on the analysis of traffic control systems, the main course of development of the conceptual designs of motor units has been defined. The systems aimed to control the course motion of the motor unit in automatic mode using the adaptive systems have been developed. The article presents structural models of the conceptual motor units based on electrically controlled systems by the operation of drive motors and adaptive systems that make the motor units completely automated.

Failure to expand the motor unit size to compensate for declining motor unit numbers distinguishes sarcopenic from non-sarcopenic older men.

PubMed

Piasecki, M; Ireland, A; Piasecki, J; Stashuk, D W; Swiecicka, A; Rutter, M K; Jones, D A; McPhee, J S

2018-05-01

The age-related loss of muscle mass is related to the loss of innervating motor neurons and denervation of muscle fibres. Not all denervated muscle fibres are degraded; some may be reinnervated by an adjacent surviving neuron, which expands the innervating motor unit proportional to the numbers of fibres rescued. Enlarged motor units have larger motor unit potentials when measured using electrophysiological techniques. We recorded much larger motor unit potentials in relatively healthy older men compared to young men, but the older men with the smallest muscles (sarcopenia) had smaller motor unit potentials than healthy older men. These findings suggest that healthy older men reinnervate large numbers of muscle fibres to compensate for declining motor neuron numbers, but a failure to do so contributes to muscle loss in sarcopenic men. Sarcopenia results from the progressive loss of skeletal muscle mass and reduced function in older age. It is likely to be associated with the well-documented reduction of motor unit numbers innervating limb muscles and the increase in size of surviving motor units via reinnervation of denervated fibres. However, no evidence exists to confirm the extent of motor unit remodelling in sarcopenic individuals. The aim of the present study was to compare motor unit size and number between young (n = 48), non-sarcopenic old (n = 13), pre-sarcopenic (n = 53) and sarcopenic (n = 29) men. Motor unit potentials (MUPs) were isolated from intramuscular and surface EMG recordings. The motor unit numbers were reduced in all groups of old compared with young men (all P < 0.001). MUPs were higher in non-sarcopenic and pre-sarcopenic men compared with young men (P = 0.039 and 0.001 respectively), but not in the vastus lateralis of sarcopenic old (P = 0.485). The results suggest that extensive motor unit remodelling occurs relatively early during ageing, exceeds the loss of muscle mass and precedes sarcopenia. Reinnervation of denervated muscle fibres probably expands the motor unit size in the non-sarcopenic and pre-sarcopenic old, but not in the sarcopenic old. These findings suggest that a failure to expand the motor unit size distinguishes sarcopenic from pre-sarcopenic muscles. © 2018 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Edaravone, a Free Radical Scavenger, Delayed Symptomatic and Pathological Progression of Motor Neuron Disease in the Wobbler Mouse.

PubMed

Ikeda, Ken; Iwasaki, Yasuo

2015-01-01

Edaravone, a free radical scavenger is used widely in Japanese patients with acute cerebral infarction. This antioxidant could have therapeutic potentials for other neurological diseases. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects the upper and the lower motor neuron, leading to death within 3-5 years after onset. A phase III clinical trial of edaravone suggested no significant effects in ALS patients. However, recent 2nd double-blind trial has demonstrated therapeutic benefits of edaravone in definite patients diagnosed by revised El Escorial diagnostic criteria of ALS. Two previous studies showed that edaravone attenuated motor symptoms or motor neuron degeneration in mutant superoxide dismutase 1-transgenic mice or rats, animal models of familial ALS. Herein we examined whether this radical scavenger can retard progression of motor dysfunction and neuropathological changes in wobbler mice, sporadic ALS-like model. After diagnosis of the disease onset at the postnatal age of 3-4 weeks, wobbler mice received edaravone (1 or 10 mg/kg, n = 10/group) or vehicle (n = 10), daily for 4 weeks by intraperitoneal administration. Motor symptoms and neuropathological changes were compared among three groups. Higher dose (10 mg/kg) of edaravone treatment significantly attenuated muscle weakness and contracture in the forelimbs, and suppressed denervation atrophy in the biceps muscle and degeneration in the cervical motor neurons compared to vehicle. Previous and the present studies indicated neuroprotective effects of edaravone in three rodent ALS-like models. This drug seems to be worth performing the clinical trial in ALS patients in the United States of American and Europe, in addition to Japan.

Edaravone, a Free Radical Scavenger, Delayed Symptomatic and Pathological Progression of Motor Neuron Disease in the Wobbler Mouse

PubMed Central

2015-01-01

Edaravone, a free radical scavenger is used widely in Japanese patients with acute cerebral infarction. This antioxidant could have therapeutic potentials for other neurological diseases. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects the upper and the lower motor neuron, leading to death within 3–5 years after onset. A phase III clinical trial of edaravone suggested no significant effects in ALS patients. However, recent 2nd double-blind trial has demonstrated therapeutic benefits of edaravone in definite patients diagnosed by revised El Escorial diagnostic criteria of ALS. Two previous studies showed that edaravone attenuated motor symptoms or motor neuron degeneration in mutant superoxide dismutase 1-transgenic mice or rats, animal models of familial ALS. Herein we examined whether this radical scavenger can retard progression of motor dysfunction and neuropathological changes in wobbler mice, sporadic ALS-like model. After diagnosis of the disease onset at the postnatal age of 3–4 weeks, wobbler mice received edaravone (1 or 10 mg/kg, n = 10/group) or vehicle (n = 10), daily for 4 weeks by intraperitoneal administration. Motor symptoms and neuropathological changes were compared among three groups. Higher dose (10 mg/kg) of edaravone treatment significantly attenuated muscle weakness and contracture in the forelimbs, and suppressed denervation atrophy in the biceps muscle and degeneration in the cervical motor neurons compared to vehicle. Previous and the present studies indicated neuroprotective effects of edaravone in three rodent ALS-like models. This drug seems to be worth performing the clinical trial in ALS patients in the United States of American and Europe, in addition to Japan. PMID:26469273

Distribution of muscle fibre conduction velocity for representative samples of motor units in the full recruitment range of the tibialis anterior muscle.

PubMed

Del Vecchio, A; Negro, F; Felici, F; Farina, D

2018-02-01

Motor units are recruited in an orderly manner according to the size of motor neurones. Moreover, because larger motor neurones innervate fibres with larger diameters than smaller motor neurones, motor units should be recruited orderly according to their conduction velocity (MUCV). Because of technical limitations, these relations have been previously tested either indirectly or in small motor unit samples that revealed weak associations between motor unit recruitment threshold (RT) and MUCV. Here, we analyse the relation between MUCV and RT for large samples of motor units. Ten healthy volunteers completed a series of isometric ankle dorsiflexions at forces up to 70% of the maximum. Multi-channel surface electromyographic signals recorded from the tibialis anterior muscle were decomposed into single motor unit action potentials, from which the corresponding motor unit RT, MUCV and action potential amplitude were estimated. Established relations between muscle fibre diameter and CV were used to estimate the fibre size. Within individual subjects, the distributions of MUCV and fibre diameters were unimodal and did not show distinct populations. MUCV was strongly correlated with RT (mean (SD) R 2  = 0.7 (0.09), P < 0.001; 406 motor units), which supported the hypothesis that fibre diameter is associated with RT. The results provide further evidence for the relations between motor neurone and muscle fibre properties for large samples of motor units. The proposed methodology for motor unit analysis has also the potential to open new perspectives in the study of chronic and acute neuromuscular adaptations to ageing, training and pathology. © 2017 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Improving Lives through Evidence-Based Practice

ERIC Educational Resources Information Center

Young Exceptional Children, 2008

2008-01-01

Tess is a joyful eight-year old girl with epilepsy, frontal lobe dysfunction, and dyspraxia, as well as delays in language, fine motor, and gross motor skills. However, despite her disabilities, Tess happily embraces life. With assistance from a few support professionals, Tess currently functions successfully in a regular education second grade…

Contemporary Theories of Perceptual-Motor Development.

ERIC Educational Resources Information Center

Nelson, Monte; Pyfer, Jean L.

Contemporary theories of perceptual-motor development and dysfunction are analyzed in detail in this review of the literature. Studies focused on observation of delays, deviations, cause, theories of development, and programs of remediation. It is suggested that it may be presumptuous for theorists to delineate three, four, or ten characteristics…

Properties of single motor units in medial gastrocnemius muscles of adult and old rats.

PubMed Central

Kadhiresan, V A; Hassett, C A; Faulkner, J A

1996-01-01

1. The purpose of this study was to determine the role of motor unit remodelling in the deficit that develops in the maximum isometric tetanic force (Fo) of whole medial gastrocnemius (MGN) muscles in old compared with adult rats. The Fo values and morphological data were determined for MGN muscles and eighty-two single motor units in muscles of adult (10-12 months) and sixty-two units in those of old (24-26 months) F344 rats. During an unfused tetanus, fast and slow (S) motor units were identified by the presence and absence of sag, respectively. Fast-fatigable (FF) and fast-fatigue-resistant (FR) units were classified by fatigue indices less than or greater than 0.50, respectively. 2. For old rats, whole MGN muscle Fo was 29% less than the value of 11.2 N measured for adult rats. The deficit in whole muscle Fo of old rats resulted from equivalent decreases in the number of motor units, 16% smaller than the adult value of ninety-seven, and in the mean motor unit Fo value, 14% less than the adult value of 117 mN. 3. With ageing, little motor unit remodelling occurred in FR units, whereas the S and FF motor units demonstrated dramatic, but opposing, changes. For S units, the number of units remained constant, but the number of fibres per motor unit increased 3-fold from 57 to 165. In contrast, the number of FF units decreased by 34% and the number of fibres per motor unit of the remaining units decreased to 86% of the adult value of 333. The age-related remodelling of motor units appeared to involve denervation of fast muscle fibres with reinnervation of denervated fibres by axonal sprouting from slow fibres. PMID:8782115

Operant treatment of orofacial dysfunction in neuromuscular disorders.

PubMed Central

Parker, L H; Cataldo, M F; Bourland, G; Emurian, C S; Corbin, R J; Page, J M

1984-01-01

The popularity and reported success of biofeedback treatment for neuromuscular disorders has occurred despite a lack of research identifying the critical variables responsible for therapeutic gain. In this study, we assessed the degree to which severe neurological dysfunction could be improved by using one of the components present in all biofeedback treatment, contingency management. Three cases of orofacial dysfunction were treated by reinforcing specific improvements reliably detectable without the use of biofeedback equipment. The results showed that contingency management procedures alone were sufficient to improve overt motor responses but, unlike biofeedback treatment, did not produce decreases in the hypertonic muscle groups associated with the trained motor behavior. The findings suggest that sophisticated, expensive biofeedback equipment may not be necessary in treating some neuromuscular disorders and that important clinical gains may be achieved by redesigning the patient's daily environment to be contingently therapeutic, rather than only accommodating the disabilities of the physically handicapped. PMID:6526764

Motor functioning in autistic spectrum disorders: a preliminary analysis.

PubMed

Behere, Aniruddh; Shahani, Lokesh; Noggle, Chad A; Dean, Raymond

2012-01-01

The study sought to identify differences in motor functioning between autism and Asperger syndrome while also assessing the diagnostic contribution of such assessment. A sample of 16 individuals with autism and 10 with Asperger syndrome completed the Dean-Woodcock Sensory-Motor Battery, and outcomes were compared. Significant differences were found in measures of cerebellar functioning, favoring Asperger subjects. Deficits in coordination, ambulation, and the Romberg test were associated with both disorders. On the basis of motor outcomes alone, 100% were accurately differentiated. Findings support the idea that motor dysfunction is a core feature of these presentations and demonstrated the utility of motor assessment in diagnostic practice.

A Simulation Based Analysis of Motor Unit Number Index (MUNIX) Technique Using Motoneuron Pool and Surface Electromyogram Models

PubMed Central

Li, Xiaoyan; Rymer, William Zev; Zhou, Ping

2013-01-01

Motor unit number index (MUNIX) measurement has recently achieved increasing attention as a tool to evaluate the progression of motoneuron diseases. In our current study, the sensitivity of the MUNIX technique to changes in motoneuron and muscle properties was explored by a simulation approach utilizing variations on published motoneuron pool and surface electromyogram (EMG) models. Our simulation results indicate that, when keeping motoneuron pool and muscle parameters unchanged and varying the input motor unit numbers to the model, then MUNIX estimates can appropriately characterize changes in motor unit numbers. Such MUNIX estimates are not sensitive to different motor unit recruitment and rate coding strategies used in the model. Furthermore, alterations in motor unit control properties do not have a significant effect on the MUNIX estimates. Neither adjustment of the motor unit recruitment range nor reduction of the motor unit firing rates jeopardizes the MUNIX estimates. The MUNIX estimates closely correlate with the maximum M wave amplitude. However, if we reduce the amplitude of each motor unit action potential rather than simply reduce motor unit number, then MUNIX estimates substantially underestimate the motor unit numbers in the muscle. These findings suggest that the current MUNIX definition is most suitable for motoneuron diseases that demonstrate secondary evidence of muscle fiber reinnervation. In this regard, when MUNIX is applied, it is of much importance to examine a parallel measurement of motor unit size index (MUSIX), defined as the ratio of the maximum M wave amplitude to the MUNIX. However, there are potential limitations in the application of the MUNIX methods in atrophied muscle, where it is unclear whether the atrophy is accompanied by loss of motor units or loss of muscle fiber size. PMID:22514208

Mitochondrial dynamics and bioenergetic dysfunction is associated with synaptic alterations in mutant SOD1 motor neurons

PubMed Central

Magrané, Jordi; Sahawneh, Mary Anne; Przedborski, Serge; Estévez, Álvaro G.; Manfredi, Giovanni

2012-01-01

Mutations in Cu,Zn superoxide dismutase (SOD1) cause familial amyotrophic lateral sclerosis (FALS), a rapidly fatal motor neuron disease. Mutant SOD1 has pleiotropic toxic effects on motor neurons, among which mitochondrial dysfunction has been proposed as one of the contributing factors in motor neuron demise. Mitochondria are highly dynamic in neurons; they are constantly reshaped by fusion and move along neurites to localize at sites of high-energy utilization, such as synapses. The finding of abnormal mitochondria accumulation in neuromuscular junctions, where the SOD1-FALS degenerative process is though to initiate, suggests that impaired mitochondrial dynamics in motor neurons may be involved in pathogenesis. We addressed this hypothesis by live imaging microscopy of photo-switchable fluorescent mitoDendra in transgenic rat motor neurons expressing mutant or wild type human SOD1. We demonstrate that mutant SOD1 motor neurons have impaired mitochondrial fusion in axons and cell bodies. Mitochondria also display selective impairment of retrograde axonal transport, with reduced frequency and velocity of movements. Fusion and transport defects are associated with smaller mitochondrial size, decreased mitochondrial density, and defective mitochondrial membrane potential. Furthermore, mislocalization of mitochondria at synapses among motor neurons, in vitro, correlates with abnormal synaptic number, structure, and function. Dynamics abnormalities are specific to mutant SOD1 motor neuron mitochondria, since they are absent in wild type SOD1 motor neurons, they do not involve other organelles, and they are not found in cortical neurons. Taken together, these results suggest that impaired mitochondrial dynamics may contribute to the selective degeneration of motor neurons in SOD1-FALS. PMID:22219285

Prevalence and mechanism of bladder dysfunction in Guillain-Barré Syndrome.

PubMed

Sakakibara, Ryuji; Uchiyama, Tomoyuki; Kuwabara, Satoshi; Mori, Masahiro; Ito, Takashi; Yamamoto, Tatsuya; Awa, Yusuke; Yamaguchi, Chiharu; Yuki, Nobuhiro; Vernino, Steven; Kishi, Masahiko; Shirai, Kohji

2009-01-01

To examine the prevalence and mechanism of urinary dysfunction in GBS. Urinary symptoms were observed and neurological examinations made repeatedly during hospitalization of 65 consecutive patients with clinico-neurophysiologically definite GBS. The patients included 41 men, 24 women; mean age, 41 years old; mean Hughes motor grade, 3; AIDP, 28, AMAN, 37. Urodynamic studies consisted of uroflowmetry, measurement of post-micturition residuals, medium-fill water cystometry, and external anal sphincter electromyography. Urinary dysfunction was observed in 27.7% of GBS cases (urinary retention, 9.2%). Urinary dysfunction was related to the Hughes motor grade (P < 0.05), defecatory dysfunction (P < 0.05), age (P < 0.05), and negatively related to serum IgG class anti-ganglioside antibody GalNAc-GD1a (P < 0.05). Urinary dysfunction was more common in AIDP (39%) than in AMAN (19%). No association was found between antibody titer against neuronal nicotinic acetylcholine receptors and urinary dysfunction. Urodynamic studies in nine patients, mostly performed within 8 weeks after disease onset, revealed post-void residual in 3 (mean 195 ml), among those who were able to urinate; decreased bladder sensation in 1; detrusor overactivity in 8; low compliance in 1; underactive detrusor in 7 (both overactive and underactive detrusor in 5); and nonrelaxing sphincter in 2. In our series of GBS cases, 27.7% of the patients had urinary dysfunction, including urinary retention in 9.2%. Underactive detrusor, overactive detrusor, and to a lesser extent, hyperactive sphincter are the major urodynamic abnormalities. The underlying mechanisms of urinary dysfunction appear to involve both hypo- and hyperactive lumbosacral nerves. Neurourol. Urodynam. 28:432-437, 2009. (c) 2009 Wiley-Liss, Inc.

Raven's Coloured Progressive Matrices as a Measure of Cognitive Functioning in Cerebral Palsy

ERIC Educational Resources Information Center

Pueyo, R.; Junque, C.; Vendrell, P.; Narberhaus, A.; Segarra, D.

2008-01-01

Background: Cognitive dysfunction is frequent in Cerebral Palsy (CP). CP motor impairment and associated speech deficits often hinder cognitive assessment, with the result being that not all CP studies consider cognitive dysfunction. Raven's Coloured Progressive Matrices is a simple, rapid test which can be used in persons with severe motor…

Digital Dysfunctions in Primary School: A Pilot Study

ERIC Educational Resources Information Center

Thorvaldsen, Steinar; Egeberg, Gunstein; Pettersen, Geir Olaf; Vavik, Lars

2011-01-01

Learning often involves complex cognitive and motorical processes, and while most learners cope adequately with these challenges there are always some that struggle. When new kinds of knowledge are introduced there is a possibility that some learners will find this new knowledge hard to acquire, and thus manifest a dysfunction. Today the new…

Neuroprotective effects of voluntary running on cognitive dysfunction in an α-synuclein rat model of Parkinson's disease.

PubMed

Crowley, Erin K; Nolan, Yvonne M; Sullivan, Aideen M

2018-05-01

Parkinson's disease (PD) is no longer primarily classified as a motor disorder due to increasing recognition of the impact on patients of several nonmotor PD symptoms, including cognitive dysfunction. These nonmotor symptoms are highly prevalent and greatly affect the quality of life of patients with PD, and so, therapeutic interventions to alleviate these symptoms are urgently needed. The aim of this study was to investigate the potential neuroprotective effects of voluntary running on cognitive dysfunction in an adeno-associated virus-α-synuclein rat model of PD. Bilateral intranigral administration of adeno-associated virus-α-synuclein was found to induce motor dysfunction and a significant loss of nigral dopaminergic neurons, neither of which were rescued by voluntary running. Overexpression of α-synuclein also resulted in significant impairment on hippocampal neurogenesis-dependent pattern separation, a cognitive task; this was rescued by voluntary running. This was substantiated by an effect of running on neurogenesis levels in the dorsal dentate gyrus, suggesting that the functional effects of running on pattern separation were mediated via increased neurogenesis. Copyright © 2018 Elsevier Inc. All rights reserved.

Neurological soft signs are associated with attentional dysfunction in children with attention deficit hyperactivity disorder.

PubMed

Pitzianti, Mariabernarda; D'Agati, Elisa; Casarelli, Livia; Pontis, Marco; Kaunzinger, Ivo; Lange, Klaus W; Tucha, Oliver; Curatolo, Paolo; Pasini, Augusto

2016-11-01

Inattention is one of the core symptoms of Attention Deficit Hyperactivity Disorder (ADHD). Most of patients with ADHD show motor impairment, consisting in the persistence of neurological soft signs (NSS). Our aim was to evaluate attentional and motor functioning in an ADHD sample and healthy children (HC) and possible link between attentional dysfunction and motor impairment in ADHD. Twenty-seven drug-naive patients with ADHD and 23 HC were tested with a test battery, measuring different aspects of attention. Motor evaluation has provided three primary variables: overflow movements (OM), dysrhythmia and total speed of timed activities. Compared to HC, patients were impaired in a considerable number of attentional processes and showed a greater number of NSS. Significant correlations between disturbances of attention and motor abnormalities were observed in ADHD group. Our findings suggest that attentional processes could be involved in the pathophysiology of the NSS and add scientific evidence to the predictive value of NSS as indicators of the severity of functional impairment in ADHD. Given the marked improvement or complete resolution of NSS following treatment with methylphenidate, we suggest that evaluation of NSS is useful to monitor the effectiveness of pharmacological treatment with MPH in ADHD.

The role of sacroiliac joint dysfunction in the genesis of low back pain: the obvious is not always right.

PubMed

Weksler, Natan; Velan, Gad J; Semionov, Michael; Gurevitch, Boris; Klein, Moti; Rozentsveig, Vsevolod; Rudich, Tzvia

2007-12-01

It is a common practice to the link low back pain with protruding disc even when neurological signs are absent. Because pain caused by sacroiliac joint dysfunction can mimic discogenic or radicular low back pain, we assumed that the diagnosis of sacroiliac joint dysfunction is frequently overlooked. To assess the incidence of sacroiliac joint dysfunction in patients with low back pain and positive disc findings on CT scan or MRI, but without claudication or objective neurological deficits. Fifty patients with low back pain and disc herniation, without claudication or neurological abnormalities such as decreased motor strength, sensory alterations or sphincter incontinence and with positive pain provocation tests for sacroiliac joint dysfunction were submitted to fluoroscopic diagnostic sacroiliac joint infiltration. The mean baseline VAS pain score was 7.8 +/- 1.77 (range 5-10). Thirty minutes after infiltration, the mean VAS score was 1.3 +/- 1.76 (median 0.000E+00 with an average deviation from median = 1.30) (P = 0.0002). Forty-six patients had a VAS score ranging from 0 to 3, 8 weeks after the fluoroscopic guided infiltration. There were no serious complications after treatment. An unanticipated motor block that required hospitalization was seen in four patients, lasting from 12 to 36 h. Sacroiliac joint dysfunction should be considered strongly in the differential diagnosis of low back pain in this group of patients.

Role of motor unit structure in defining function

NASA Technical Reports Server (NTRS)

Monti, R. J.; Roy, R. R.; Edgerton, V. R.

2001-01-01

Motor units, defined as a motoneuron and all of its associated muscle fibers, are the basic functional units of skeletal muscle. Their activity represents the final output of the central nervous system, and their role in motor control has been widely studied. However, there has been relatively little work focused on the mechanical significance of recruiting variable numbers of motor units during different motor tasks. This review focuses on factors ranging from molecular to macroanatomical components that influence the mechanical output of a motor unit in the context of the whole muscle. These factors range from the mechanical properties of different muscle fiber types to the unique morphology of the muscle fibers constituting a motor unit of a given type and to the arrangement of those motor unit fibers in three dimensions within the muscle. We suggest that as a result of the integration of multiple levels of structural and physiological levels of organization, unique mechanical properties of motor units are likely to emerge. Copyright 2001 John Wiley & Sons, Inc.

Understanding Parkinson Disease: A Complex and Multifaceted Illness.

PubMed

Gopalakrishna, Apoorva; Alexander, Sheila A

2015-12-01

Parkinson disease is an incredibly complex and multifaceted illness affecting millions of people in the United States. Parkinson disease is characterized by progressive dopaminergic neuronal dysfunction and loss, leading to debilitating motor, cognitive, and behavioral symptoms. Parkinson disease is an enigmatic illness that is still extensively researched today to search for a better understanding of the disease, develop therapeutic interventions to halt or slow progression of the disease, and optimize patient outcomes. This article aims to examine in detail the normal function of the basal ganglia and dopaminergic neurons in the central nervous system, the etiology and pathophysiology of Parkinson disease, related signs and symptoms, current treatment, and finally, the profound impact of understanding the disease on nursing care.

Adjustments differ among low-threshold motor units during intermittent, isometric contractions.

PubMed

Farina, Dario; Holobar, Ales; Gazzoni, Marco; Zazula, Damjan; Merletti, Roberto; Enoka, Roger M

2009-01-01

We investigated the changes in muscle fiber conduction velocity, recruitment and derecruitment thresholds, and discharge rate of low-threshold motor units during a series of ramp contractions. The aim was to compare the adjustments in motor unit activity relative to the duration that each motor unit was active during the task. Multichannel surface electromyographic (EMG) signals were recorded from the abductor pollicis brevis muscle of eight healthy men during 12-s contractions (n = 25) in which the force increased and decreased linearly from 0 to 10% of the maximum. The maximal force exhibited a modest decline (8.5 +/- 9.3%; P < 0.05) at the end of the task. The discharge times of 73 motor units that were active for 16-98% of the time during the first five contractions were identified throughout the task by decomposition of the EMG signals. Action potential conduction velocity decreased during the task by a greater amount for motor units that were initially active for >70% of the time compared with that of less active motor units. Moreover, recruitment and derecruitment thresholds increased for these most active motor units, whereas the thresholds decreased for the less active motor units. Another 18 motor units were recruited at an average of 171 +/- 32 s after the beginning of the task. The recruitment and derecruitment thresholds of these units decreased during the task, but muscle fiber conduction velocity did not change. These results indicate that low-threshold motor units exhibit individual adjustments in muscle fiber conduction velocity and motor neuron activation that depended on the relative duration of activity during intermittent contractions.

Motor unit firing rates and synchronisation affect the fractal dimension of simulated surface electromyogram during isometric/isotonic contraction of vastus lateralis muscle.

PubMed

Mesin, Luca; Dardanello, Davide; Rainoldi, Alberto; Boccia, Gennaro

2016-12-01

During fatiguing contractions, many adjustments in motor units behaviour occur: decrease in muscle fibre conduction velocity; increase in motor units synchronisation; modulation of motor units firing rate; increase in variability of motor units inter-spike interval. We simulated the influence of all these adjustments on synthetic EMG signals in isometric/isotonic conditions. The fractal dimension of the EMG signal was found mainly influenced by motor units firing behaviour, being affected by both firing rate and synchronisation level, and least affected by muscle fibre conduction velocity. None of the calculated EMG indices was able to discriminate between firing rate and motor units synchronisation. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

[Kinematic movement analyses and their application in psychiatry].

PubMed

Juckel, Georg; Mergl, Roland; Hegerl, Ulrich

2005-04-01

There is a long tradition to develop valid instruments for the exact assessment of psycho-motor dysfunctions in psychiatry. However, progress is hampered by the complexity of emotionally driven movements in psychiatric patients. Methods used up to now either remains unspecific due to only qualitative measurements or focus on the neurophysiological aspects too much. Thus, the results accomplished so far are only very general unspecific concerning different groups of psychiatric patients. In this paper, two own methods are presented which are aimed to avoid the two poles above mentioned. Kinematic analyses of facial expressions as well as handwriting movements provide quantitative and quite specific informations about psycho-motor dysfunctions of psychiatric patients and the effects of psychotropic substances. Thus, these methods are well suitable for relating them to other neurobiological parameters in order to contribute to the pathophysiological understanding of psycho-motor symptoms in psychiatric patients.

Methods for the assessment of peripheral muscle fatigue and its energy and metabolic determinants in COPD.

PubMed

Rondelli, Rafaella Rezende; Dal Corso, Simone; Simões, Alexandre; Malaguti, Carla

2009-11-01

It has been well established that, in addition to the pulmonary involvement, COPD has systemic consequences that can lead to peripheral muscle dysfunction, with greater muscle fatigue, lower exercise tolerance and lower survival in these patients. In view of the negative repercussions of early muscle fatigue in COPD, the objective of this review was to discuss the principal findings in the literature on the metabolic and bioenergy determinants of muscle fatigue, its functional repercussions, as well as the methods for its identification and quantification. The anatomical and functional substrate of higher muscle fatigue in COPD appears to include lower levels of high-energy phosphates, lower mitochondrial density, early lactacidemia, higher serum ammonia and reduced muscle perfusion. These alterations can be revealed by contraction failure, decreased firing rates of motor units and increased recruitment of motor units in a given activity, which can be functionally detected by a reduction in muscle strength, power and endurance. This review article also shows that various types of muscle contraction regimens and protocols have been used in order to detect muscle fatigue in this population. With this understanding, rehabilitation strategies can be developed in order to improve the resistance to muscle fatigue in this population.

Functional mapping of the pelvic floor and sphincter muscles from high-density surface EMG recordings.

PubMed

Peng, Yun; He, Jinbao; Khavari, Rose; Boone, Timothy B; Zhang, Yingchun

2016-11-01

Knowledge of the innervation of pelvic floor and sphincter muscles is of great importance to understanding the pathophysiology of female pelvic floor dysfunctions. This report presents our high-density intravaginal and intrarectal electromyography (EMG) probes and a comprehensive innervation zone (IZ) imaging technique based on high-density EMG readings to characterize the IZ distribution. Both intravaginal and intrarectal probes are covered with a high-density surface electromyography electrode grid (8 × 8). Surface EMG signals were acquired in ten healthy women performing maximum voluntary contractions of their pelvic floor. EMG decomposition was performed to separate motor-unit action potentials (MUAPs) and then localize their IZs. High-density surface EMG signals were successfully acquired over the vaginal and rectal surfaces. The propagation patterns of muscle activity were clearly visualized for multiple muscle groups of the pelvic floor and anal sphincter. During each contraction, up to 218 and 456 repetitions of motor units were detected by the vaginal and rectal probes, respectively. MUAPs were separated with their IZs identified at various orientations and depths. The proposed probes are capable of providing a comprehensive mapping of IZs of the pelvic floor and sphincter muscles. They can be employed as diagnostic and preventative tools in clinical practices.

Isometric contractions of motor units in a fast twitch muscle of the cat

PubMed Central

Bagust, J.; Knott, Sarah; Lewis, D. M.; Luck, J. C.; Westerman, R. A.

1973-01-01

1. Isosmetric contractions of cat flexor digitorum longus whole muscles and of functionally isolated motor units have been measured under conditions similar to those used by Buller & Lewis (1965a). 2. Motor unit twitch time to peak was inversely related to axonal conduction velocity. The logarithm of tetanic tension was directly related to conduction velocity. These relationships suggest that each motoneurone has an influence on the muscle fibres which it innervates. 3. The ratio of twitch to tetanic tension was directly related to the time to peak of the motor unit. This fact might be explained by variation between motor units of the duration of `active state'. 4. The muscle length at which tension was maximal varied between motor units and the optima were found over the range of muscle lengths which could occur in the body. Slow motor units had longer optimal lengths. 5. The sample of motor units was considered to be unbiased because the distribution of axon conduction velocities was compatible with reported motor fibre diameter spectra of the muscle nerve. The mean motor unit tetanic tension gave a reasonable estimate of the number of α-motor axons in the muscle nerve. Twitch tensions gave a value that was 40% higher. 6. Motor unit and whole muscle data were in good agreement for length-tetanus tension curves, for times to peak and for twitch-tetanus ratios at long muscle lengths. PMID:4715372

Recruitment and derecruitment characteristics of motor units in a hand muscle of young and old adults.

PubMed

Jesunathadas, Mark; Marmon, Adam R; Gibb, James M; Enoka, Roger M

2010-06-01

The significant decline in motor neuron number after approximately 60 yr of age is accompanied by a remodeling of the neuromuscular system so that average motor unit force increases and the ability of old adults to produce an intended force declines. One possible explanation for the loss of movement precision is that the remodeling increases the difference in recruitment forces between successively recruited motor units in old adults and this augments force variability at motor unit recruitment. The purpose of the study was to compare the forces and discharge characteristics of motor units in a hand muscle of young and old adults at motor unit recruitment and derecruitment. The difference in recruitment force between pairs of motor units did not differ between young (n=54) and old adults (n=56; P=0.702). However, old adults had a greater proportion of contractions in which motor units discharged action potentials transiently before discharging continuously during the ramp increase in force (young: 0.32; old: 0.41; P=0.045). Force variability at motor unit recruitment was greater for old adults compared with young adults (Por=0.729). These results suggest that the difference in force between the recruitment of successive motor units does not differ between age groups, but that motor unit recruitment may be more transient and could contribute to the greater variability in force observed in old adults during graded ramp contractions.

Auditory- and Vestibular-Evoked Potentials Correlate with Motor and Non-Motor Features of Parkinson’s Disease

PubMed Central

Shalash, Ali Soliman; Hassan, Dalia Mohamed; Elrassas, Hanan Hani; Salama, Mohamed Mosaad; Méndez-Hernández, Edna; Salas-Pacheco, José M.; Arias-Carrión, Oscar

2017-01-01

Degeneration of several brainstem nuclei has been long related to motor and non-motor symptoms (NMSs) of Parkinson’s disease (PD). Nevertheless, due to technical issues, there are only a few studies that correlate that association. Brainstem auditory-evoked potential (BAEP) and vestibular-evoked myogenic potential (VEMP) responses represent a valuable tool for brainstem assessment. Here, we investigated the abnormalities of BAEPs, ocular VEMPs (oVEMPs), and cervical VEMPs (cVEMPs) in patients with PD and its correlation to the motor and NMSs. Fifteen patients diagnosed as idiopathic PD were evaluated by Unified Parkinson’s Disease Rating Scale and its subscores, Hoehn and Yahr scale, Schwab and England scale, and Non-Motor Symptoms Scale. PD patients underwent pure-tone, speech audiometry, tympanometry, BAEP, oVEMPs, and cVEMPs, and compared to 15 age-matched control subjects. PD subjects showed abnormal BAEP wave morphology, prolonged absolute latencies of wave V and I–V interpeak latencies. Absent responses were the marked abnormality seen in oVEMP. Prolonged latencies with reduced amplitudes were seen in cVEMP responses. Rigidity and bradykinesia were correlated to the BAEP and cVEMP responses contralateral to the clinically more affected side. Contralateral and ipsilateral cVEMPs were significantly correlated to sleep (p = 0.03 and 0.001), perception (p = 0.03), memory/cognition (p = 0.025), and urinary scores (p = 0.03). The oVEMP responses showed significant correlations to cardiovascular (p = 0.01) and sexual dysfunctions (p = 0.013). PD is associated with BAEP and VEMP abnormalities that are correlated to the motor and some non-motor clinical characteristics. These abnormalities could be considered as potential electrophysiological biomarkers for brainstem dysfunction and its associated motor and non-motor features. PMID:28289399

Neural reorganization underlies improvement in stroke-induced motor dysfunction by music-supported therapy.

PubMed

Altenmüller, E; Marco-Pallares, J; Münte, T F; Schneider, S

2009-07-01

Motor impairments are common after stroke, but efficacious therapies for these dysfunctions are scarce. By extending an earlier study on the effects of music-supported therapy, behavioral indices of motor function as well as electrophysiological measures were obtained before and after a series of therapy sessions to assess whether this new treatment leads to neural reorganization and motor recovery in patients after stroke. The study group comprised 32 stroke patients in a large rehabilitation hospital; they had moderately impaired motor function and no previous musical experience. Over a period of 3 weeks, these patients received 15 sessions of music-supported therapy using a manualized step-by-step approach. For comparison 30 additional patients received standard rehabilitation procedures. Fine as well as gross motor skills were trained by using either a MIDI-piano or electronic drum pads programmed to emit piano tones. Motor functions were assessed by an extensive test battery. In addition, we studied event-related desynchronization/synchronization and coherences from all 62 patients performing self-paced movements of the index finger (MIDI-piano) and of the whole arm (drum pads). Results showed that music-supported therapy yielded significant improvement in fine as well as gross motor skills with respect to speed, precision, and smoothness of movements. Neurophysiological data showed a more pronounced event-related desynchronization before movement onset and a more pronounced coherence in the music-supported therapy group in the post-training assessment, whereas almost no differences were observed in the control group. Thus we see that music-supported therapy leads to marked improvements of motor function after stroke and that these are accompanied by electrophysiological changes indicative of a better cortical connectivity and improved activation of the motor cortex.

Involvement of PKA/DARPP-32/PP1α and β- arrestin/Akt/GSK-3β Signaling in Cadmium-Induced DA-D2 Receptor-Mediated Motor Dysfunctions: Protective Role of Quercetin.

PubMed

Gupta, Richa; Shukla, Rajendra K; Pandey, Ankita; Sharma, Tanuj; Dhuriya, Yogesh K; Srivastava, Pranay; Singh, Manjul P; Siddiqi, Mohammad Imran; Pant, Aditya B; Khanna, Vinay K

2018-02-06

Given increasing risk of cadmium-induced neurotoxicity, the study was conducted to delineate the molecular mechanisms associated with cadmium-induced motor dysfunctions and identify targets that govern dopaminergic signaling in the brain involving in vivo, in vitro, and in silico approaches. Selective decrease in dopamine (DA)-D2 receptors on cadmium exposure was evident which affected the post-synaptic PKA/DARPP-32/PP1α and β-arrestin/Akt/GSK-3β signaling concurrently in rat corpus striatum and PC12 cells. Pharmacological inhibition of PKA and Akt in vitro demonstrates that both pathways are independently modulated by DA-D2 receptors and associated with cadmium-induced motor deficits. Ultrastructural changes in the corpus striatum demonstrated neuronal degeneration and loss of synapse on cadmium exposure. Further, molecular docking provided interesting evidence that decrease in DA-D2 receptors may be due to direct binding of cadmium at the competitive site of dopamine on DA-D2 receptors. Treatment with quercetin resulted in the alleviation of cadmium-induced behavioral and neurochemical alterations. This is the first report demonstrating that cadmium-induced motor deficits are associated with alteration in postsynaptic dopaminergic signaling due to a decrease in DA-D2 receptors in the corpus striatum. The results further demonstrate that quercetin has the potential to alleviate cadmium-induced dopaminergic dysfunctions.

The Recovery of Walking in Stroke Patients: A Review

ERIC Educational Resources Information Center

Jang, Sung Ho

2010-01-01

We reviewed the literature on walking recovery of stroke patients as it relates to the following subjects: epidemiology of walking dysfunction, recovery course of walking, and recovery mechanism of walking (neural control of normal walking, the evaluation methods for leg motor function, and motor recovery mechanism of leg). The recovery of walking…

Dramatic Effects of Speech Task on Motor and Linguistic Planning in Severely Dysfluent Parkinsonian Speech

ERIC Educational Resources Information Center

Van Lancker Sidtis, Diana; Cameron, Krista; Sidtis, John J.

2012-01-01

In motor speech disorders, dysarthric features impacting intelligibility, articulation, fluency and voice emerge more saliently in conversation than in repetition, reading or singing. A role of the basal ganglia in these task discrepancies has been identified. Further, more recent studies of naturalistic speech in basal ganglia dysfunction have…

Timing Deficits Are Implicated in Motor Dysfunction in Asperger's Syndrome

ERIC Educational Resources Information Center

Price, Kelly J.; Edgell, Dorothy; Kerns, Kimberly A.

2012-01-01

This study addressed what role movement timing irregularities have in producing the motor deficits documented in Asperger's Syndrome (AS). Participants included males with AS (n = 14) and without (n = 16), matched by age (7-23 years) and with no significant IQ differences. They completed measures of timing perception (comparisons of tempo of…

Ocular Motor Indicators of Executive Dysfunction in Fragile X and Turner Syndromes

ERIC Educational Resources Information Center

Lasker, Adrian G.; Mazzocco, Michele M. M.; Zee, David S.

2007-01-01

Fragile X and Turner syndromes are two X-chromosome-related disorders associated with executive function and visual spatial deficits. In the present study, we used ocular motor paradigms to examine evidence that disruption to different neurological pathways underlies these deficits. We tested 17 females with fragile X, 19 females with Turner…

Parkinson's: a syndrome rather than a disease?

PubMed

Titova, Nataliya; Padmakumar, C; Lewis, Simon J G; Chaudhuri, K Ray

2017-08-01

Emerging concepts suggest that a multitude of pathology ranging from misfolding of alpha-synuclein to neuroinflammation, mitochondrial dysfunction, and neurotransmitter driven alteration of brain neuronal networks lead to a syndrome that is commonly known as Parkinson's disease. The complex underlying pathology which may involve degeneration of non-dopaminergic pathways leads to the expression of a range of non-motor symptoms from the prodromal stage of Parkinson's to the palliative stage. Non-motor clinical subtypes, cognitive and non-cognitive, have now been proposed paving the way for possible subtype specific and non-motor treatments, a key unmet need currently. Natural history of these subtypes remains unclear and need to be defined. In addition to in vivo biomarkers which suggest variable involvement of the cholinergic and noradrenergic patterns of the Parkinson syndrome, abnormal alpha-synuclein accumulation have now been demonstrated in the gut, pancreas, heart, salivary glands, and skin suggesting that Parkinson's is a multi-organ disorder. The Parkinson's phenotype is thus not just a dopaminergic motor syndrome, but a dysfunctional multi-neurotransmitter pathway driven central and peripheral nervous system disorder that possibly ought to be considered a syndrome and not a disease.

THE USE OF VISUAL TRAINING AND POSTURAL REMEDIATION WITH GROUPS OF COLLEGE STUDENTS.

ERIC Educational Resources Information Center

JONES, EVE

RESEARCH HAS SHOWN THE RELATIONSHIP OF VISUAL-MOTOR DYSFUNCTIONS TO READING DIFFICULTIES AND SCHOOL FAILURE. THIS STUDY WAS DESIGNED TO IDENTIFY THE EXTENT OF SUCH DYSFUNCTIONS IN SEVERAL GROUPS OF FULL-TIME DAY STUDENTS AND TO ASSESS THE FEASIBILITY OF VISUAL TRAINING AND POSTURE REMEDIATION METHODS FOR STUDENTS ON ACADEMIC PROBATION. WHILE THE…

Dependence of the paired motor unit analysis on motor unit discharge characteristics in the human tibialis anterior muscle

PubMed Central

Stephenson, Jennifer L.; Maluf, Katrina S.

2011-01-01

The paired motor unit analysis provides in vivo estimates of the magnitude of persistent inward currents (PIC) in human motoneurons by quantifying changes in the firing rate (ΔF) of an earlier recruited (reference) motor unit at the time of recruitment and derecruitment of a later recruited (test) motor unit. This study assessed the variability of ΔF estimates, and quantified the dependence of ΔF on the discharge characteristics of the motor units selected for analysis. ΔF was calculated for 158 pairs of motor units recorded from nine healthy individuals during repeated submaximal contractions of the tibialis anterior muscle. The mean (SD) ΔF was 3.7 (2.5) pps (range −4.2 to 8.9 pps). The median absolute difference in ΔF for the same motor unit pair across trials was 1.8 pps, and the minimal detectable change in ΔF required to exceed measurement error was 4.8 pps. ΔF was positively related to the amount of discharge rate modulation in the reference motor unit (r2=0.335; P<0.001), and inversely related to the rate of increase in discharge rate (r2=0.125; P<0.001). A quadratic function provided the best fit for relations between ΔF and the time between recruitment of the reference and test motor units (r2=0.229, P<0.001), the duration of test motor unit activity (r2=0.110, P<0.001), and the recruitment threshold of the test motor unit (r2=0.237, P<0.001). Physiological and methodological contributions to the variability in ΔF estimates of PIC magnitude are discussed, and selection criteria to reduce these sources of variability are suggested for the paired motor unit analysis. PMID:21459110

Detection of Hand and Leg Motor Tract Injury Using Novel Diffusion Tensor MRI Tractography in Children with Central Motor Dysfunction

PubMed Central

Jeong, Jeong-Won; Lee, Jessica; Kamson, David O.; Chugani, Harry T.; JuhÁsz, Csaba

2015-01-01

Purpose To examine whether an objective segmenation of corticospinal tract (CST) associated with hand and leg movements can be used to detect central motor weakness in the corresponding extremities in a pediatric population. Material and Methods This retrospective study included diffusion tensor imaging (DTI) of 25 children with central paresis affecting at least one limb (age: 9.0±4.2 years, 15 boys, 5/13/7 children with left/right/both hemispheric lesions including ischemia, cyst, and gliosis), as well as 42 pediatric control subjects with no motor dysfunction (age: 9.0±5.5 years, 21 boys, 31 healthy/11 non-lesional epilepsy children). Leg- and hand-related CST pathways were segmented using DTI-maximum a posteriori (DTI-MAP) classification. The resulting CST volumes were then divided by total supratentorial white matter volume, resulting in a marker called “normalized streamline volume ratio (NSVR)” to quantify the degree of axonal loss in separate CST pathways associated with leg and hand motor functions. A receiver operating characteristic curve was applied to measure the accuracy of this marker to identify extremities with motor weakness. Results NSVR values of hand/leg CST selectively achieved the following values of accuracy/sensitivity/specificity: 0.84/0.84/0.57, 0.82/0.81/0.55, 0.78/0.75/0.55, 0.79/0.81/0.54 at a cut-off of 0.03/0.03/0.03/0.02 for right hand CST, left hand CST, right leg CST, and left leg CST, respectively. Motor weakness of hand and leg was most likely present at the cut-off values of hand and leg NSVR (i.e., 0.029/0.028/0.025/0.020 for left-hand/right-hand/left-leg/right-leg). The control group showed a moderate age-related increase in absolute CST volumes and a biphasic age-related variation of the normalized CST volumes, which were lacking in the paretic children. Conclusions This study demonstrates that DTI-MAP classification may provide a new imaging tool to quantify axonal loss in children with central motor dysfunction. Using this technique, we found that early-life brain lesions affect the maturational trajectory of the primary motor pathway which may be used as an effective marker to facilitate evidence-based treatment of paretic children. PMID:25959649

Detection of hand and leg motor tract injury using novel diffusion tensor MRI tractography in children with central motor dysfunction.

PubMed

Jeong, Jeong-Won; Lee, Jessica; Kamson, David O; Chugani, Harry T; Juhász, Csaba

2015-09-01

To examine whether an objective segmenation of corticospinal tract (CST) associated with hand and leg movements can be used to detect central motor weakness in the corresponding extremities in a pediatric population. This retrospective study included diffusion tensor imaging (DTI) of 25 children with central paresis affecting at least one limb (age: 9.0±4.2years, 15 boys, 5/13/7 children with left/right/both hemispheric lesions including ischemia, cyst, and gliosis), as well as 42 pediatric control subjects with no motor dysfunction (age: 9.0±5.5years, 21 boys, 31 healthy/11 non-lesional epilepsy children). Leg- and hand-related CST pathways were segmented using DTI-maximum a posteriori (DTI-MAP) classification. The resulting CST volumes were then divided by total supratentorial white matter volume, resulting in a marker called "normalized streamline volume ratio (NSVR)" to quantify the degree of axonal loss in separate CST pathways associated with leg and hand motor functions. A receiver operating characteristic curve was applied to measure the accuracy of this marker to identify extremities with motor weakness. NSVR values of hand/leg CST selectively achieved the following values of accuracy/sensitivity/specificity: 0.84/0.84/0.57, 0.82/0.81/0.55, 0.78/0.75/0.55, 0.79/0.81/0.54 at a cut-off of 0.03/0.03/0.03/0.02 for right hand CST, left hand CST, right leg CST, and left leg CST, respectively. Motor weakness of hand and leg was most likely present at the cut-off values of hand and leg NSVR (i.e., 0.029/0.028/0.025/0.020 for left-hand/right-hand/left-leg/right-leg). The control group showed a moderate age-related increase in absolute CST volumes and a biphasic age-related variation of the normalized CST volumes, which were lacking in the paretic children. This study demonstrates that DTI-MAP classification may provide a new imaging tool to quantify axonal loss in children with central motor dysfunction. Using this technique, we found that early-life brain lesions affect the maturational trajectory of the primary motor pathway which may be used as an effective marker to facilitate evidence-based treatment of paretic children. Copyright © 2015 Elsevier Inc. All rights reserved.

Prader-Willi syndrome: atypical psychoses and motor dysfunctions.

PubMed

Verhoeven, Willem M A; Tuinier, Siegfried

2006-01-01

Prader-Willi syndrome (PWS) is the result of a lack of expression of genes on the paternally derived chromosome 15q11-q13 and can be considered as a hypothalamic disorder. Its behavioral phenotype is characterized by ritualistic, stereotyped, and compulsive behaviors as well as motor abnormalities. After adolescence, recurrent affective psychoses are relatively frequent, especially in patients with uniparental disomy. These psychotic states have a subacute onset with complete recovery and comprise an increase of psychomotor symptoms that show resemblance with catatonia. Some evidence has emerged that gamma-aminobutyric acid (GABA) dysfunctionality is involved in both PWS and catatonia. Treatment of these atypical psychoses should preferably include GABA mimetic compounds like lorazepam, valproic acid, and possibly topiramate.

Early functional impairment of sensory-motor connectivity in a mouse model of spinal muscular atrophy

PubMed Central

Mentis, George Z.; Blivis, Dvir; Liu, Wenfang; Drobac, Estelle; Crowder, Melissa E.; Kong, Lingling; Alvarez, Francisco J.; Sumner, Charlotte J.; O'Donovan, Michael J.

2011-01-01

SUMMARY To define alterations of neuronal connectivity that occur during motor neuron degeneration, we characterized the function and structure of spinal circuitry in spinal muscular atrophy (SMA) model mice. SMA motor neurons show reduced proprioceptive reflexes that correlate with decreased number and function of synapses on motor neuron somata and proximal dendrites. These abnormalities occur at an early stage of disease in motor neurons innervating proximal hindlimb muscles and medial motor neurons innervating axial muscles, but only at end-stage disease in motor neurons innervating distal hindlimb muscles. Motor neuron loss follows afferent synapse loss with the same temporal and topographical pattern. Trichostatin A, which improves motor behavior and survival of SMA mice, partially restores spinal reflexes illustrating the reversibility of these synaptic defects. De-afferentation of motor neurons is an early event in SMA and may be a primary cause of motor dysfunction that is amenable to therapeutic intervention. PMID:21315257

Motor unit activity after eccentric exercise and muscle damage in humans.

PubMed

Semmler, J G

2014-04-01

It is well known that unaccustomed eccentric exercise leads to muscle damage and soreness, which can produce long-lasting effects on muscle function. How this muscle damage influences muscle activation is poorly understood. The purpose of this brief review is to highlight the effect of eccentric exercise on the activation of muscle by the nervous system, by examining the change in motor unit activity obtained from surface electromyography (EMG) and intramuscular recordings. Previous research shows that eccentric exercise produces unusual changes in the EMG–force relation that influences motor performance during isometric, shortening and lengthening muscle contractions and during fatiguing tasks. When examining the effect of eccentric exercise at the single motor unit level, there are substantial changes in recruitment thresholds, discharge rates, motor unit conduction velocities and synchronization, which can last for up to 1 week after eccentric exercise. Examining the time course of these changes suggests that the increased submaximal EMG after eccentric exercise most likely occurs through a decrease in motor unit conduction velocity and an increase in motor unit activity related to antagonist muscle coactivation and low-frequency fatigue. Furthermore, there is a commonly held view that eccentric exercise produces preferential damage to high-threshold motor units, but the evidence for this in humans is limited. Further research is needed to establish whether there is preferential damage to high-threshold motor units after eccentric exercise in humans, preferably by linking changes in motor unit activity with estimates of motor unit size using selective intramuscular recording techniques.

The effect of fast and slow motor unit activation on whole-muscle mechanical performance: the size principle may not pose a mechanical paradox

PubMed Central

Holt, N. C.; Wakeling, J. M.; Biewener, A. A.

2014-01-01

The output of skeletal muscle can be varied by selectively recruiting different motor units. However, our knowledge of muscle function is largely derived from muscle in which all motor units are activated. This discrepancy may limit our understanding of in vivo muscle function. Hence, this study aimed to characterize the mechanical properties of muscle with different motor unit activation. We determined the isometric properties and isotonic force–velocity relationship of rat plantaris muscles in situ with all of the muscle active, 30% of the muscle containing predominately slower motor units active or 20% of the muscle containing predominately faster motor units active. There was a significant effect of active motor unit type on isometric force rise time (p < 0.001) and the force–velocity relationship (p < 0.001). Surprisingly, force rise time was longer and maximum shortening velocity higher when all motor units were active than when either fast or slow motor units were selectively activated. We propose this is due to the greater relative effects of factors such as series compliance and muscle resistance to shortening during sub-maximal contractions. The findings presented here suggest that recruitment according to the size principle, where slow motor units are activated first and faster ones recruited as demand increases, may not pose a mechanical paradox, as has been previously suggested. PMID:24695429

The effect of fast and slow motor unit activation on whole-muscle mechanical performance: the size principle may not pose a mechanical paradox.

PubMed

Holt, N C; Wakeling, J M; Biewener, A A

2014-05-22

The output of skeletal muscle can be varied by selectively recruiting different motor units. However, our knowledge of muscle function is largely derived from muscle in which all motor units are activated. This discrepancy may limit our understanding of in vivo muscle function. Hence, this study aimed to characterize the mechanical properties of muscle with different motor unit activation. We determined the isometric properties and isotonic force-velocity relationship of rat plantaris muscles in situ with all of the muscle active, 30% of the muscle containing predominately slower motor units active or 20% of the muscle containing predominately faster motor units active. There was a significant effect of active motor unit type on isometric force rise time (p < 0.001) and the force-velocity relationship (p < 0.001). Surprisingly, force rise time was longer and maximum shortening velocity higher when all motor units were active than when either fast or slow motor units were selectively activated. We propose this is due to the greater relative effects of factors such as series compliance and muscle resistance to shortening during sub-maximal contractions. The findings presented here suggest that recruitment according to the size principle, where slow motor units are activated first and faster ones recruited as demand increases, may not pose a mechanical paradox, as has been previously suggested.

Spine Topographical Distribution of Skin α-Synuclein Deposits in Idiopathic Parkinson Disease.

PubMed

Donadio, Vincenzo; Incensi, Alex; Rizzo, Giovanni; Scaglione, Cesa; Capellari, Sabina; Fileccia, Enrico; Avoni, Patrizia; Liguori, Rocco

2017-05-01

Phosphorylated α-synuclein (p-syn) in skin nerves mainly in the proximal sites is a promising neurodegenerative biomarker for idiopathic Parkinson disease (IPD). However, the p-syn spine distribution particularly in patients with unilateral motor dysfunctions remains undefined. This study aimed to investigate in IPD p-syn differences between left and right cervical spine sites in patients with prevalent unilateral motor symptoms, and cervical and thoracic spine sites in patients with bilateral motor symptoms. We enrolled 28 IPD patients fulfilling clinical diagnostic criteria associated with abnormal nigro-striatal DatScan and cardiac MIBG: 15 with prevalently unilateral motor symptoms demonstrated by DatScan; 13 with bilateral motor symptoms and DatScan abnormalities. Patients underwent skin biopsy searching for intraneural p-syn deposits: skin samples were taken from C7 paravertebral left and right sites in unilateral patients and from cervical (C7) and thoracic (Th12) paravertebral spine regions in bilateral patients. Unilateral patients displayed 20% of abnormal p-syn deposits in the affected motor site, 60% in both sites and 20% only in the non-affected site. P-syn was found in all patients in C7 but in only 62% of patients in Th12. Our data showed that cervical p-syn deposits displayed a uniform distribution between both sides not following the motor dysfunction in unilateral patients, and skin nerve p-syn deposits demonstrated a spine gradient with the cervical site expressing the highest positivity. © 2017 American Association of Neuropathologists, Inc. All rights reserved.

Evaluation of mirrored muscle activity in patients with Complex Regional Pain Syndrome.

PubMed

Bank, Paulina J M; Peper, C Lieke E; Marinus, Johan; Beek, Peter J; van Hilten, Jacobus J

2014-10-01

Motor dysfunction in Complex Regional Pain Syndrome (CRPS) has been associated with bilateral changes in central motor processing, suggesting abnormal coupling between the affected and unaffected limb. We evaluated the occurrence of involuntary muscle activity in a limb during voluntary movements of the contralateral limb (i.e., mirror activity) in unilaterally affected patients to examine disinhibition of contralateral motor activity in CRPS. Mirror activity was examined during unimanual rhythmic flexion-extension movements of the wrist through in-depth analysis of electromyography recordings from the passive arm in 20 CRPS patients and 40 controls. The number of mirror-epochs was comparable for both arms in both CRPS patients and controls. Mirror-epochs in the affected arm of patients were comparable to those in controls. Mirror-epochs in the unaffected arm were shorter and showed less resemblance (in terms of rhythm and timing) to activity of the homologous muscle in the moving arm compared to mirror-epochs in controls. No evidence for disinhibition of contralateral motor activity was found during unimanual movement. Although motor dysfunction in CRPS has been associated with bilateral changes in cortical motor processing, the present findings argue against disinhibition of interhemispheric projections to homologous muscles in the contralateral limb during unimanual movement. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Cognitive and Motor Aspects of Parkinson's Disease Associated with Dysphagia.

PubMed

Kim, Ji Sun; Youn, Jinyoung; Suh, Mee Kyung; Kim, Tae-Eun; Chin, Juhee; Park, Suyeon; Cho, Jin Whan

2015-11-01

Dysphagia is a common symptom and an important prognostic factor in Parkinson's disease (PD). Although cognitive and motor dysfunctions may contribute to dysphagia in patients with PD, any specific association between such problems and swallowing functions is unclear. Here, we examined the potential relationship between cognitive/motor components and swallowing functions in PD. We evaluated the contributions of cognition and motor function to the components of swallowing via video fluoroscopic swallowing (VFS) experiments. We prospectively enrolled 56 patients without dementia having PD. Parkinson's disease severity was assessed by the Unified Parkinson's Disease Rating Scale (UPDRS). All participants received neuropsychological tests covering general mental status, visuospatial function, attention, language, learning and memory, and frontal executive function. The well-validated "modified barium swallow impairment profile" scoring system was applied during VFS studies to quantify swallowing impairments. Finally, correlations between neuropsychological or motor functions and impairment in swallowing components were calculated. The most significant correlations were found between the frontal/executive or learning/memory domains and the oral phase of swallowing, though a minor component of the pharyngeal phase correlated with frontal function as well. Bradykinesia and the UPDRS total score were associated with both the pharyngeal and oral phases. Our findings suggest that cognitive dysfunctions are associated with the oral phase of swallowing in patients with early stage PD while the severity of motor symptoms may be associated with overall swallowing function.

Single motor unit firing rate after stroke is higher on the less-affected side during stable low-level voluntary contractions

PubMed Central

McNulty, Penelope A.; Lin, Gaven; Doust, Catherine G.

2014-01-01

Muscle weakness is the most common outcome after stroke and a leading cause of adult-acquired motor disability. Single motor unit properties provide insight into the mechanisms of post-stroke motor impairment. Motor units on the more-affected side are reported to have lower peak firing rates, reduced discharge variability and a more compressed dynamic range than healthy subjects. The activity of 169 motor units was discriminated from surface electromyography in 28 stroke patients during sustained voluntary contractions 10% of maximal and compared to 110 units recorded in 16 healthy subjects. Motor units were recorded in three series: ankle dorsiflexion, wrist flexion and elbow flexion. Mean firing rates after stroke were significantly lower on the more-affected than the less-affected side (p < 0.001) with no differences between dominant and non-dominant sides for healthy subjects. When data were combined, firing rates on the less-affected side were significantly higher than those either on the more-affected side or healthy subjects (p < 0.001). Motor unit mean firing rate was higher in the upper-limb than the lower-limb (p < 0.05). The coefficient of variation of motor unit discharge rate was lower for motor units after stroke compared to controls for wrist flexion (p < 0.05) but not ankle dorsiflexion. However the dynamic range of motor units was compressed only for motor units on the more-affected side during wrist flexion. Our results show that the pathological change in motor unit firing rate occurs on the less-affected side after stroke and not the more-affected side as previously reported, and suggest that motor unit behavior recorded in a single muscle after stroke cannot be generalized to muscles acting on other joints even within the same limb. These data emphasize that the less-affected side does not provide a valid control for physiological studies on the more-affected side after stroke and that both sides should be compared to data from age- and sex-matched healthy subjects. PMID:25100969

Esophageal involvement and interstitial lung disease in mixed connective tissue disease.

PubMed

Fagundes, M N; Caleiro, M T C; Navarro-Rodriguez, T; Baldi, B G; Kavakama, J; Salge, J M; Kairalla, R; Carvalho, C R R

2009-06-01

Mixed connective tissue disease is a systemic inflammatory disorder that results in both pulmonary and esophageal manifestations. We sought to evaluate the relationship between esophageal dysfunction and interstitial lung disease in patients with mixed connective tissue disease. We correlated the pulmonary function data and the high-resolution computed tomography findings of interstitial lung disease with the results of esophageal evaluation in manometry, 24-hour intraesophageal pH measurements, and the presence of esophageal dilatation on computed tomography scan. Fifty consecutive patients with mixed connective tissue disease, according to Kasukawa's classification criteria, were included in this prospective study. High-resolution computed tomography parenchymal abnormalities were present in 39 of 50 patients. Esophageal dilatation, gastroesophageal reflux, and esophageal motor impairment were also very prevalent (28 of 50, 18 of 36, and 30 of 36, respectively). The presence of interstitial lung disease on computed tomography was significantly higher among patients with esophageal dilatation (92% vs. 45%; p<0.01) and among patients with severe motor dysfunction (90% vs. 35%; p<0.001). Although we were not able to prove a causal relationship between esophageal and pulmonary involvement, our series revealed a strong association between esophageal motor dysfunction and interstitial lung disease in patients with mixed connective tissue disease.

Non-Stationarity and Power Spectral Shifts in EMG Activity Reflect Motor Unit Recruitment in Rat Diaphragm Muscle

PubMed Central

Seven, Yasin B.; Mantilla, Carlos B.; Zhan, Wen-Zhi; Sieck, Gary C.

2012-01-01

We hypothesized that diaphragm muscle (DIAm) by a shift in the EMG power spectral density (PSD) to higher frequencies reflects recruitment of more fatigable fast-twitch motor units and motor unit recruitment is reflected by EMG non-stationarity. DIAm EMG was recorded in anesthetized rats during eupnea, hypoxia-hypercapnia (10% O2-5% CO2), airway occlusion, and sneezing (maximal DIAm force). Although power in all frequency bands increased progressively across motor behaviors, PSD centroid frequency increased only during sneezing (p<0.05). The non-stationary period at the onset of EMG activity ranged from ~70 ms during airway occlusion to ~150 ms during eupnea. Within the initial non-stationary period of EMG activity 80–95% of motor units were recruited during different motor behaviors. Motor units augmented their discharge frequencies progressively beyond the non-stationary period; yet, EMG signal became stationary. In conclusion, non-stationarity of DIAm EMG reflects the period of motor unit recruitment, while a shift in the PSD towards higher frequencies reflects recruitment of more fatigable fast-twitch motor units. PMID:22986086

[The cerebellum as a major player in motor disturbances related to Autistic Syndrome Disorders].

PubMed

Jaber, M

2017-04-01

Autism spectrum disorders (ASD) are neurodevelopmental disorders associated with disturbances in communication, social interactions, cognition and affect. ASD are also accompanied by complex movement disorders, including ataxia. A special focus of recent research in this area is made on the striatum and the cerebellum, two structures known not only to control movement but also to be involved in cognitive functions such as memory and language. Dysfunction within the motor system may be associated with abnormal movements in ASD that are translated into ataxia, abnormal pattern of righting, gait sequencing, development of walking, and hand positioning. This line of study may generate new knowledge and understanding of motor symptoms associated with ASD and aims to deliver fresh perspectives for early diagnosis and therapeutic strategies against ASD. Despite the relative paucity of research in this area (compared to the social, linguistic, and behavioural disturbances in ASD), there is evidence that the frontostriatal motor system and/or the cerebellar motor systems may be the site of dysfunction in ASD. Indeed, the cerebellum seems to be essential in the development of basic social capabilities, communication, repetitive/restrictive behaviors, and motor and cognitive behaviors that are all impaired in ASD. Cerebellar neuropathology including cerebellar hypoplasia and reduced cerebellar Purkinje cell numbers are the most consistent neuropathologies linked to ASD. The functional state of the cerebellum and its impact on brain function in ASD is the focus of this review. This review starts by recapitulating historical findings pointing towards an implication of the cerebellum, and to a lesser extent the basal ganglia structures, in TSA. We then detail the structure/function of the cerebellum at the regional and cellular levels before describing human and animal findings indicating a role of the cerebellum and basal ganglia in ASD. Several studies have attempted to identify the nature of the motor system dysfunction in ASD, and it became apparent that the motor fronto-striatal and cerebellar systems are major sites of dysfunction in this psychiatric illness. Anomalies in these structures have been revealed both at the anatomical and functional levels in human patients as well as in animal models. These models are obtained by manipulation of genes that are often implicated in glutamate transmission, by lesions of brain structures among which the cerebellum, by pharmacological treatment with drugs such as the Valproate or by maternal infections with bacterial membrane extracts of double stranded RNA mimicking a viral infection. The "cognitive approach" has dominated ASD research for three decades and led to the design of interventional strategies, which have yielded satisfactory results. Nevertheless, new approaches and alternative hypotheses on the aetiology and diagnosis of ASD are needed. Research focused on motor rather than psychiatric symptoms may have a greater potential to elucidate the neurobiological basis of ASD. Copyright © 2016 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

Visuo-Motor and Cognitive Procedural Learning in Children with Basal Ganglia Pathology

ERIC Educational Resources Information Center

Mayor-Dubois, C.; Maeder, P.; Zesiger, P.; Roulet-Perez, E.

2010-01-01

We investigated procedural learning in 18 children with basal ganglia (BG) lesions or dysfunctions of various aetiologies, using a visuo-motor learning test, the Serial Reaction Time (SRT) task, and a cognitive learning test, the Probabilistic Classification Learning (PCL) task. We compared patients with early (less than 1 year old, n=9), later…

Hybrid-fuel bacterial flagellar motors in Escherichia coli

PubMed Central

Sowa, Yoshiyuki; Homma, Michio; Ishijima, Akihiko; Berry, Richard M.

2014-01-01

The bacterial flagellar motor rotates driven by an electrochemical ion gradient across the cytoplasmic membrane, either H+ or Na+ ions. The motor consists of a rotor ∼50 nm in diameter surrounded by multiple torque-generating ion-conducting stator units. Stator units exchange spontaneously between the motor and a pool in the cytoplasmic membrane on a timescale of minutes, and their stability in the motor is dependent upon the ion gradient. We report a genetically engineered hybrid-fuel flagellar motor in Escherichia coli that contains both H+- and Na+-driven stator components and runs on both types of ion gradient. We controlled the number of each type of stator unit in the motor by protein expression levels and Na+ concentration ([Na+]), using speed changes of single motors driving 1-μm polystyrene beads to determine stator unit numbers. De-energized motors changed from locked to freely rotating on a timescale similar to that of spontaneous stator unit exchange. Hybrid motor speed is simply the sum of speeds attributable to individual stator units of each type. With Na+ and H+ stator components expressed at high and medium levels, respectively, Na+ stator units dominate at high [Na+] and are replaced by H+ units when Na+ is removed. Thus, competition between stator units for spaces in a motor and sensitivity of each type to its own ion gradient combine to allow hybrid motors to adapt to the prevailing ion gradient. We speculate that a similar process may occur in species that naturally express both H+ and Na+ stator components sharing a common rotor. PMID:24550452

Motor Unit Changes Seen With Skeletal Muscle Sarcopenia in Oldest Old Rats

PubMed Central

Kung, Theodore A.; van der Meulen, Jack H.; Urbanchek, Melanie G.; Kuzon, William M.; Faulkner, John A.

2014-01-01

Sarcopenia leads to many changes in skeletal muscle that contribute to atrophy, force deficits, and subsequent frailty. The purpose of this study was to characterize motor unit remodeling related to sarcopenia seen in extreme old age. Whole extensor digitorum longus muscle and motor unit contractile properties were measured in 19 adult (11–13 months) and 12 oldest old (36–37 months) Brown-Norway rats. Compared with adults, oldest old rats had significantly fewer motor units per muscle, smaller muscle cross-sectional area, and lower muscle specific force. However, mean motor unit force generation was similar between the two groups due to an increase in innervation ratio by the oldest old rats. These findings suggest that even in extreme old age both fast- and slow-twitch motor units maintain the ability to undergo motor unit remodeling that offsets some effects of sarcopenia. PMID:24077596

Characteristics of the Motor Units during Sternocleidomastoid Isometric Flexion among Patients with Mechanical Neck Disorder and Asymptomatic Individuals.

PubMed

Yang, Chia-Chi; Su, Fong-Chin; Yang, Po-Ching; Lin, Hwai-Ting; Guo, Lan-Yuen

2016-01-01

Mechanical neck disorder is a widespread and non-neurological musculoskeletal condition resulting from modern lifestyles. Presently, the fundamental electrophysiological properties of the motor units of the sternocleidomastoid muscles and the characteristics of the short-term synchronization of the motor unit in patients with neck pain are ambiguous. This study therefore aims to clarify the fundamental electrophysiological properties of the motor units of the sternocleidomastoid muscles in patients with mechanical neck disorder and in asymptomatic individuals. We further investigated whether alterations in the degree of motor unit short-term synchronization occur. The surface electrophysiological signals of the bilateral sternal heads of the sternocleidomastoid muscles of twelve patients with mechanical neck disorder and asymptomatic individuals were detected at 25% of the maximum voluntary contraction during cervical isometric flexion and then decomposed into individual motor unit action potential trains. We found that the patients with mechanical neck disorder showed significantly higher initial and mean firing rates of the sternocleidomastoid muscles and displayed substantially lower motor unit short-term synchronization values compared with the asymptomatic subjects. Consequently, these convincing findings support the assertion that patients with mechanical neck disorder display altered neuromuscular control strategies, such as the reinforcement of motor unit recruitment firing rates in the sternocleidomastoid muscles. The motor units of these patients also revealed neural recruitment strategies with relatively poor efficiency when executing the required motor tasks.

Characteristics of the Motor Units during Sternocleidomastoid Isometric Flexion among Patients with Mechanical Neck Disorder and Asymptomatic Individuals

PubMed Central

Yang, Chia-Chi; Su, Fong-Chin; Yang, Po-Ching; Lin, Hwai-Ting

2016-01-01

Mechanical neck disorder is a widespread and non-neurological musculoskeletal condition resulting from modern lifestyles. Presently, the fundamental electrophysiological properties of the motor units of the sternocleidomastoid muscles and the characteristics of the short-term synchronization of the motor unit in patients with neck pain are ambiguous. This study therefore aims to clarify the fundamental electrophysiological properties of the motor units of the sternocleidomastoid muscles in patients with mechanical neck disorder and in asymptomatic individuals. We further investigated whether alterations in the degree of motor unit short-term synchronization occur. The surface electrophysiological signals of the bilateral sternal heads of the sternocleidomastoid muscles of twelve patients with mechanical neck disorder and asymptomatic individuals were detected at 25% of the maximum voluntary contraction during cervical isometric flexion and then decomposed into individual motor unit action potential trains. We found that the patients with mechanical neck disorder showed significantly higher initial and mean firing rates of the sternocleidomastoid muscles and displayed substantially lower motor unit short-term synchronization values compared with the asymptomatic subjects. Consequently, these convincing findings support the assertion that patients with mechanical neck disorder display altered neuromuscular control strategies, such as the reinforcement of motor unit recruitment firing rates in the sternocleidomastoid muscles. The motor units of these patients also revealed neural recruitment strategies with relatively poor efficiency when executing the required motor tasks. PMID:27941995

Candesartan, rather than losartan, improves motor dysfunction in thioacetamide-induced chronic liver failure in rats

PubMed Central

Murad, H.A.; Gazzaz, Z.J.; Ali, S.S.; Ibraheem, M.S.

2017-01-01

Minimal hepatic encephalopathy is more common than the acute syndrome. Losartan, the first angiotensin-II receptor blocker (ARB), and candesartan, another widely-used ARB, have protected against developing fibrogenesis, but there is no clear data about their curative antifibrotic effects. The current study was designed to examine their effects in an already-established model of hepatic fibrosis and also their effects on the associated motor dysfunction. Low-grade chronic liver failure (CLF) was induced in 3-month old Sprague-Dawley male rats using thioacetamide (TAA, 50 mg·kg−1·day−1) intraperitoneally for 2 weeks. The TAA-CLF rats were randomly divided into five groups (n=8) treated orally for 14 days (mg·kg−1·day−1) as follows: TAA (distilled water), losartan (5 and 10 mg/kg), and candesartan (0.1 and 0.3 mg/kg). Rats were tested for rotarod and open-field tests. Serum and hepatic biochemical markers, and hepatic histopathological changes were evaluated by H&E and Masson's staining. The TAA-CLF rats showed significant increases of hepatic malondialdehyde, hepatic expression of tumor necrosis factor-α (TNF-α), and serum ammonia, alanine aminotransferase, γ-glutamyl transferase, TNF-α, and malondialdehyde levels as well as significant decreases of hepatic and serum glutathione levels. All treatments significantly reversed these changes. The histopathological changes were moderate in losartan-5 and candesartan-0.1 groups and mild in losartan-10 and candesartan-0.3 groups. Only candesartan significantly improved TAA-induced motor dysfunction. In conclusion, therapeutic antifibrotic effects of losartan and candesartan in thioacetamide-induced hepatic fibrosis in rats are possibly through angiotensin-II receptor blocking, antioxidant, and anti-inflammatory activities. Improved motor dysfunction by candesartan could be attributed to better brain penetration and slower “off-rate” from angiotensin-II receptors. Clinical trials are recommended. PMID:28953991

Candesartan, rather than losartan, improves motor dysfunction in thioacetamide-induced chronic liver failure in rats.

PubMed

Murad, H A; Gazzaz, Z J; Ali, S S; Ibraheem, M S

2017-09-21

Minimal hepatic encephalopathy is more common than the acute syndrome. Losartan, the first angiotensin-II receptor blocker (ARB), and candesartan, another widely-used ARB, have protected against developing fibrogenesis, but there is no clear data about their curative antifibrotic effects. The current study was designed to examine their effects in an already-established model of hepatic fibrosis and also their effects on the associated motor dysfunction. Low-grade chronic liver failure (CLF) was induced in 3-month old Sprague-Dawley male rats using thioacetamide (TAA, 50 mg·kg-1·day-1) intraperitoneally for 2 weeks. The TAA-CLF rats were randomly divided into five groups (n=8) treated orally for 14 days (mg·kg-1·day-1) as follows: TAA (distilled water), losartan (5 and 10 mg/kg), and candesartan (0.1 and 0.3 mg/kg). Rats were tested for rotarod and open-field tests. Serum and hepatic biochemical markers, and hepatic histopathological changes were evaluated by H&E and Masson's staining. The TAA-CLF rats showed significant increases of hepatic malondialdehyde, hepatic expression of tumor necrosis factor-α (TNF-α), and serum ammonia, alanine aminotransferase, γ-glutamyl transferase, TNF-α, and malondialdehyde levels as well as significant decreases of hepatic and serum glutathione levels. All treatments significantly reversed these changes. The histopathological changes were moderate in losartan-5 and candesartan-0.1 groups and mild in losartan-10 and candesartan-0.3 groups. Only candesartan significantly improved TAA-induced motor dysfunction. In conclusion, therapeutic antifibrotic effects of losartan and candesartan in thioacetamide-induced hepatic fibrosis in rats are possibly through angiotensin-II receptor blocking, antioxidant, and anti-inflammatory activities. Improved motor dysfunction by candesartan could be attributed to better brain penetration and slower "off-rate" from angiotensin-II receptors. Clinical trials are recommended.

Contribution from motor unit firing adaptations and muscle co-activation during fatigue.

PubMed

Contessa, Paola; Letizi, John; De Luca, Gianluca; Kline, Joshua C

2018-03-14

The control of motor unit firing behavior during fatigue is still debated in the literature. Most studies agree that the central nervous system increases the excitation to the motoneuron pool to compensate for decreased force contributions of individual motor units and sustain muscle force output during fatigue. However, some studies claim that motor units may decrease their firing rates despite increased excitation, contradicting the direct relationship between firing rates and excitation that governs the voluntary control of motor units. To investigate whether the control of motor units in fact changes with fatigue, we measured motor unit firing behavior during repeated contractions of the first dorsal interosseous (FDI) muscle while concurrently monitoring the activation of surrounding muscles - including the flexor carpi radialis, extensor carpi radialis, and pronator teres. Across all subjects, we observed an overall increase in FDI activation and motor unit firing rates by the end of the fatigue task. However, in some subjects we observed increases in FDI activation and motor unit firing rates only during the initial phase of the fatigue task, followed by subsequent decreases during the late phase of the fatigue task while the co-activation of surrounding muscles increased. These findings indicate that the strategy for sustaining force output may occasionally change leading to increases in the relative activation of surrounding muscles while the excitation to the fatiguing muscle decreases. Importantly, irrespective of changes in the strategy for sustaining force output, the control properties regulating motor unit firing behavior remain unchanged during fatigue.

Adult mouse motor units develop almost all of their force in the subprimary range: a new all-or-none strategy for force recruitment?

PubMed

Manuel, Marin; Heckman, C J

2011-10-19

Classical studies of the mammalian neuromuscular system have shown an impressive adaptation match between the intrinsic properties of motoneurons and the contractile properties of their motor units. In these studies, the rate at which motoneurons start to fire repetitively corresponds to the rate at which individual twitches start to sum, and the firing rate increases linearly with the amount of excitation ("primary range") up to the point where the motor unit develops its maximal force. This allows for the gradation of the force produced by a motor unit by rate modulation. In adult mouse motoneurons, however, we recently described a regime of firing ("subprimary range") that appears at lower excitation than what is required for the primary range, a finding that might challenge the classical conception. To investigate the force production of mouse motor units, we simultaneously recorded, for the first time, the motoneuron discharge elicited by intracellular ramps of current and the force developed by its motor unit. We showed that the motor unit developed nearly its maximal force during the subprimary range. This was found to be the case regardless of the input resistance of the motoneuron, the contraction speed, or the tetanic force of the motor unit. Our work suggests that force modulation in small mammals mainly relies on the number of motor units that are recruited rather than on rate modulation of individual motor units.

Architecture of Vagal Motor Units Controlling Striated Muscle of Esophagus: Peripheral Elements Patterning Peristalsis?

PubMed Central

Powley, Terry L.; Mittal, Ravinder K.; Baronowsky, Elizabeth A.; Hudson, Cherie N.; Martin, Felecia N.; McAdams, Jennifer L.; Mason, Jacqueline K.; Phillips, Robert J.

2013-01-01

Little is known about the architecture of the vagal motor units that control esophageal striated muscle, in spite of the fact that these units are necessary, and responsible, for peristalsis. The present experiment was designed to characterize the motor neuron projection fields and terminal arbors forming esophageal motor units. Nucleus ambiguus compact formation neurons of the rat were labeled by bilateral intracranial injections of the anterograde tracer dextran biotin. After tracer transport, thoracic and abdominal esophagi were removed and prepared as whole mounts of muscle wall without mucosa or submucosa. Labeled terminal arbors of individual vagal motor neurons (n = 78) in the esophageal wall were inventoried, digitized and analyzed morphometrically. The size of individual vagal motor units innervating striated muscle, throughout thoracic and abdominal esophagus, averaged 52 endplates per motor neuron, a value indicative of fine motor control. A majority (77%) of the motor terminal arbors also issued one or more collateral branches that contacted neurons, including nitric oxide synthase-positive neurons, of local myenteric ganglia. Individual motor neuron terminal arbors co-innervated, or supplied endplates in tandem to, both longitudinal and circular muscle fibers in roughly similar proportions (i.e., two endplates to longitudinal for every three endplates to circular fibers). Both the observation that vagal motor unit collaterals project to myenteric ganglia and the fact that individual motor units co-innervate longitudinal and circular muscle layers are consistent with the hypothesis that elements contributing to peristaltic programming inhere, or are “hardwired,” in the peripheral architecture of esophageal motor units. PMID:24044976

Architecture of vagal motor units controlling striated muscle of esophagus: peripheral elements patterning peristalsis?

PubMed

Powley, Terry L; Mittal, Ravinder K; Baronowsky, Elizabeth A; Hudson, Cherie N; Martin, Felecia N; McAdams, Jennifer L; Mason, Jacqueline K; Phillips, Robert J

2013-12-01

Little is known about the architecture of the vagal motor units that control esophageal striated muscle, in spite of the fact that these units are necessary, and responsible, for peristalsis. The present experiment was designed to characterize the motor neuron projection fields and terminal arbors forming esophageal motor units. Nucleus ambiguus compact formation neurons of the rat were labeled by bilateral intracranial injections of the anterograde tracer dextran biotin. After tracer transport, thoracic and abdominal esophagi were removed and prepared as whole mounts of muscle wall without mucosa or submucosa. Labeled terminal arbors of individual vagal motor neurons (n=78) in the esophageal wall were inventoried, digitized and analyzed morphometrically. The size of individual vagal motor units innervating striated muscle, throughout thoracic and abdominal esophagus, averaged 52 endplates per motor neuron, a value indicative of fine motor control. A majority (77%) of the motor terminal arbors also issued one or more collateral branches that contacted neurons, including nitric oxide synthase-positive neurons, of local myenteric ganglia. Individual motor neuron terminal arbors co-innervated, or supplied endplates in tandem to, both longitudinal and circular muscle fibers in roughly similar proportions (i.e., two endplates to longitudinal for every three endplates to circular fibers). Both the observation that vagal motor unit collaterals project to myenteric ganglia and the fact that individual motor units co-innervate longitudinal and circular muscle layers are consistent with the hypothesis that elements contributing to peristaltic programming inhere, or are "hardwired," in the peripheral architecture of esophageal motor units. © 2013.

Motor unit recruitment and derecruitment induced by brief increase in contraction amplitude of the human trapezius muscle

PubMed Central

Westad, C; Westgaard, R H; De Luca, C J

2003-01-01

The activity pattern of low-threshold human trapezius motor units was examined in response to brief, voluntary increases in contraction amplitude (‘EMG pulse’) superimposed on a constant contraction at 4–7% of the surface electromyographic (EMG) response at maximal voluntary contraction (4–7% EMGmax). EMG pulses at 15–20% EMGmax were superimposed every minute on contractions of 5, 10, or 30 min duration. A quadrifilar fine-wire electrode recorded single motor unit activity and a surface electrode recorded simultaneously the surface EMG signal. Low-threshold motor units recruited at the start of the contraction were observed to stop firing while motor units of higher recruitment threshold stayed active. Derecruitment of a motor unit coincided with the end of an EMG pulse. The lowest-threshold motor units showed only brief silent periods. Some motor units with recruitment threshold up to 5% EMGmax higher than the constant contraction level were recruited during an EMG pulse and kept firing throughout the contraction. Following an EMG pulse, there was a marked reduction in motor unit firing rates upon return of the surface EMG signal to the constant contraction level, outlasting the EMG pulse by 4 s on average. The reduction in firing rates may serve as a trigger to induce derecruitment. We speculate that the silent periods following derecruitment may be due to deactivation of non-inactivating inward current (‘plateau potentials’). The firing behaviour of trapezius motor units in these experiments may thus illustrate a mechanism and a control strategy to reduce fatigue of motor units with sustained activity patterns. PMID:14561844

[The mirror neuron system in motor and sensory rehabilitation].

PubMed

Oouchida, Yutaka; Izumi, Shinichi

2014-06-01

The discovery of the mirror neuron system has dramatically changed the study of motor control in neuroscience. The mirror neuron system provides a conceptual framework covering the aspects of motor as well as sensory functions in motor control. Previous studies of motor control can be classified as studies of motor or sensory functions, and these two classes of studies appear to have advanced independently. In rehabilitation requiring motor learning, such as relearning movement after limb paresis, however, sensory information of feedback for motor output as well as motor command are essential. During rehabilitation from chronic pain, motor exercise is one of the most effective treatments for pain caused by dysfunction in the sensory system. In rehabilitation where total intervention unifying the motor and sensory aspects of motor control is important, learning through imitation, which is associated with the mirror neuron system can be effective and suitable. In this paper, we introduce the clinical applications of imitated movement in rehabilitation from motor impairment after brain damage and phantom limb pain after limb amputation.

Neuroscience Literacy: "Brain Tells" as Signals of Brain Dysfunction Affecting Daily Life.

PubMed

Royeen, Charlotte B; Brašić, James R; Dvorak, Leah; Provoziak-O'Brien, Casey; Sethi, Chetna; Ahmad, S Omar

2016-01-01

The structures and circuits of the central and the peripheral nervous systems provide the basis for thinking, speaking, experiencing sensations, and performing perceptual and motor activities in daily life. Healthy people experience normal functioning without giving brain functions a second thought, while dysfunction of the neural circuits may lead to marked impairments in cognition, communication, sensory awareness, and performing perceptual and motor tasks. Neuroscience literacy provides the knowledge to associate the deficits observed in patients with the underlying deficits in the structures and circuits of the nervous system. The purpose of this paper is to begin the conversation in this area via a neuroscience literacy model of "Brain Tells," defined as stereotypical or observable behaviors often associated with brain dysfunction. Occupational therapists and other allied health professionals should be alert for the signs of "Brain Tells" that may be early warning signs of brain pathology. We also suggest that neuroscience literacy be emphasized in training provided to public safety workers, teachers, caregivers, and health care professionals at all levels.

External self-representations improve self-awareness in a child with autism.

PubMed

Root, Nicholas B; Case, Laura K; Burrus, Caley J; Ramachandran, V S

2015-01-01

We have previously suggested that the social symptoms of autism spectrum disorder (ASD) could be caused in part by a dysfunctional mirror neuron system (MNS). Since the recursive activity of a functioning MNS might enable the brain to integrate visual and motor sensations into a coherent body schema, the deficits in self-awareness often seen in ASD might be caused by the same mirror neuron dysfunction. CL is an autistic adolescent who is profoundly fascinated with his reflection, looking in mirrors at every opportunity. We demonstrate that CL's abnormal gait improves significantly when using a mirror for visual feedback. We also show that both the fascination and the happiness that CL derives from looking at a computer-generated reflection diminish when a delay is introduced between the camera input and screen output. We believe that immediate, real-time visual feedback allows CL to integrate motor sensations with external visual ones into a coherent body schema that he cannot internally generate, perhaps due to a dysfunctional MNS.

Long lasting dysautonomia due to botulinum toxin B poisoning: clinical-laboratory follow up and difficulties in initial diagnosis.

PubMed

Potulska-Chromik, Anna; Zakrzewska-Pniewska, Beata; Szmidt-Sałkowska, Elżbieta; Lewandowski, Jacek; Siński, Maciej; Przyjałkowski, Witold; Kostera-Pruszczyk, Anna

2013-10-30

Botulism is an acute form of poisoning caused by one of four types (A, B, E, F) toxins produced by Clostridium botulinum, ananaerobic, spore forming bacillus. Usually diagnosis of botulism is considered in patients with predominant motor symptoms: muscle weakness with intact sensation and preserved mental function. We report a case of 56-year-old Caucasian female with a history of arterial hypertension, who presented with acute respiratory failure and bilateral ptosis misdiagnosed as brainstem ischemia. She had severe external and internal ophtalmoplegia, and autonomic dysfunction with neither motor nor sensory symptoms from upper and lower limbs. Diagnosis of botulinum toxin poisoning was made and confirmed by serum antibody testing in the mouse inoculation test. Ophtalmoplegia, autonomic dysfunction and respiratory failure can be caused by botulism. Early treatment and intensive care is essential for survival and recovery. The electrophysiological tests are crucial to correct and rapid diagnosis. Botulism (especially type B) should be considered in any case of acute or predominant isolated autonomic dysfunction.

[Post-polio syndrome. Part I. The "legacy" of forgotten disease, challenges for professionals and polio survivors].

PubMed

Matyja, Ewa

2012-01-01

The outcome of paralytic polio was believed to be a stable neurological state. Now, it is established that polio has an additional, slowly progressive phase, called post-polio syndrome (PPS) that develops 30-40 years after the acute poliomyelitis in 25-80% of paralytic and about 40% of nonparalytic polio survivors. The clinical symptoms are nonspecific and usually include muscle weakness, fatigue and muscle or joint pain. Some patients suffer from muscular atrophy, respiratory insufficiency, dysphagia, sleep disturbances or cold intolerance. The etiopathogenesis of PPS is unclear and many factors, such as dysfunction of the surviving motor units, aging, defects of neuromuscular transmission, persistence of viral infection and immunological mechanisms, are considered.

Recruitment and rate coding organisation for soleus motor units across entire range of voluntary isometric plantar flexions.

PubMed

Oya, Tomomichi; Riek, Stephan; Cresswell, Andrew G

2009-10-01

Unlike upper limb muscles, it remains undocumented as to how motor units in the soleus muscle are organised in terms of recruitment range and discharge rates with respect to their recruitment and de-recruitment thresholds. The possible influence of neuromodulation, such as persistent inward currents (PICs) on lower limb motor unit recruitment and discharge rates has also yet to be reported. To address these issues, electromyographic (EMG) activities from the soleus muscle were recorded using selective branched-wire intramuscular electrodes during ramp-and-hold contractions with intensities up to maximal voluntary contraction (MVC). The multiple single motor unit activities were then derived using a decomposition technique. The onset-offset hysteresis of motor unit discharge, i.e. a difference between recruitment and de-recruitment thresholds, as well as PIC magnitude calculated by a paired motor unit analysis were used to examine the neuromodulatory effects on discharge behaviours, such as minimum firing rate, peak firing rate and degree of increase in firing rate. Forty-two clearly identified motor units from five subjects revealed that soleus motor units are recruited progressively from rest to contraction strengths close to 95% of MVC, with low-threshold motor units discharging action potentials slower at their recruitment and with a lower peak rate than later recruited high-threshold units. This observation is in contrast to the 'onion skin phenomenon' often reported for the upper limb muscles. Based on positive correlations of the peak discharge rates, initial rates and recruitment order of the units with the magnitude of the onset-offset hysteresis and not PIC contribution, we conclude that discharge behaviours among motor units appear to be related to a variation in an intrinsic property other than PICs.

Therapeutic Effects of Anthocyanins and Environmental Enrichment in R6/1 Huntington's Disease Mice.

PubMed

Kreilaus, Fabian; Spiro, Adena S; Hannan, Anthony J; Garner, Brett; Jenner, Andrew M

2016-10-01

Huntington's disease (HD) is a progressive neurodegenerative disease with no effective treatment or cure. Environmental enrichment has been used to slow processes leading to ageing and neurodegenerative diseases including HD. Phenolic phytochemicals including anthocyanins have also been shown to improve brain function in ageing and neurodegenerative diseases. This study examined the effects of anthocyanin dietary supplementation and environmental enrichment on behavioural phenotypes and brain cholesterol metabolic alterations in the R6/1 mouse model of HD. R6/1 HD mice and their wild-type littermate controls were randomised into the different experimental conditions, involving either environmentally enriched versus standard housing conditions, or anthocyanin versus control diet. Motor dysfunction was assessed from 6 to 26 weeks using the RotaRod and the hind-paw clasping tests. Gas chromatography - tandem mass spectrometry was used to quantify a broad range of sterols in the striatum and cortex of R6/1 HD mice. Anthocyanin dietary supplementation delayed the onset of motor dysfunction in female HD mice. Environmental enrichment improved motor function and the hind paw clasping phenotype in male HD mice only. These mice also had lower levels of cholesterol oxidation products in the cortex compared to standard-housed mice. Both anthocyanin supplementation and environmental enrichment are able to improve the motor dysfunction phenotype of R6/1 mice, however the effectiveness of these interventions was different between the two sexes. The interventions examined did not alter brain cholesterol metabolic deficits that have been reported previously in this mouse model of HD.

Interhemispheric connectivity in amyotrophic lateral sclerosis: A near-infrared spectroscopy and diffusion tensor imaging study.

PubMed

Kopitzki, Klaus; Oldag, Andreas; Sweeney-Reed, Catherine M; Machts, Judith; Veit, Maria; Kaufmann, Jörn; Hinrichs, Hermann; Heinze, Hans-Jochen; Kollewe, Katja; Petri, Susanne; Mohammadi, Bahram; Dengler, Reinhard; Kupsch, Andreas R; Vielhaber, Stefan

2016-01-01

Aim of the present study was to investigate potential impairment of non-motor areas in amyotrophic lateral sclerosis (ALS) using near-infrared spectroscopy (NIRS) and diffusion tensor imaging (DTI). In particular, we evaluated whether homotopic resting-state functional connectivity (rs-FC) of non-motor associated cortical areas correlates with clinical parameters and disease-specific degeneration of the corpus callosum (CC) in ALS. Interhemispheric homotopic rs-FC was assessed in 31 patients and 30 healthy controls (HCs) for 8 cortical sites, from prefrontal to occipital cortex, using NIRS. DTI was performed in a subgroup of 21 patients. All patients were evaluated for cognitive dysfunction in the executive, memory, and visuospatial domains. ALS patients displayed an altered spatial pattern of correlation between homotopic rs-FC values when compared to HCs ( p  = 0.000013). In patients without executive dysfunction a strong correlation existed between the rate of motor decline and homotopic rs-FC of the anterior temporal lobes (ATLs) (ρ = - 0.85, p  = 0.0004). Furthermore, antero-temporal homotopic rs-FC correlated with fractional anisotropy in the central corpus callosum (CC), corticospinal tracts (CSTs), and forceps minor as determined by DTI ( p  < 0.05). The present study further supports involvement of non-motor areas in ALS. Our results render homotopic rs-FC as assessed by NIRS a potential clinical marker for disease progression rate in ALS patients without executive dysfunction and a potential anatomical marker for ALS-specific degeneration of the CC and CSTs.

Motor symptoms in Parkinson's disease: A unified framework.

PubMed

Moustafa, Ahmed A; Chakravarthy, Srinivasa; Phillips, Joseph R; Gupta, Ankur; Keri, Szabolcs; Polner, Bertalan; Frank, Michael J; Jahanshahi, Marjan

2016-09-01

Parkinson's disease (PD) is characterized by a range of motor symptoms. Besides the cardinal symptoms (akinesia and bradykinesia, tremor and rigidity), PD patients show additional motor deficits, including: gait disturbance, impaired handwriting, grip force and speech deficits, among others. Some of these motor symptoms (e.g., deficits of gait, speech, and handwriting) have similar clinical profiles, neural substrates, and respond similarly to dopaminergic medication and deep brain stimulation (DBS). Here, we provide an extensive review of the clinical characteristics and neural substrates of each of these motor symptoms, to highlight precisely how PD and its medical and surgical treatments impact motor symptoms. In conclusion, we offer a unified framework for understanding the range of motor symptoms in PD. We argue that various motor symptoms in PD reflect dysfunction of neural structures responsible for action selection, motor sequencing, and coordination and execution of movement. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vincristine and fine motor function of children with acute lymphoblastic leukemia

PubMed

Sabarre, Cheryl L; Rassekh, Shahrad R; Zwicker, Jill G

2014-10-01

Children with acute lymphoblastic leukemia receive vincristine, a chemotherapy drug known to cause peripheral neuropathy. Yet, few studies have examined the association of vincristine to fine motor function. This study will describe the fine motor skills and function of children with acute lymphoblastic leukemia on maintenance vincristine. A prospective case series design assessed manual dexterity and parent-reported fine motor dysfunction of 15 children with acute lymphoblastic leukemia in relation to cumulative vincristine exposure. Almost half of the participants had below-average fine motor skills compared to age-related norms, and 57% of parents observed functional motor problems in their children. No significant associations were found between vincristine, manual dexterity, and functional motor skills. Early detection and intervention for fine motor difficulties is suggested. Research with a larger sample is necessary to further explore the association of vincristine and fine motor function in this clinical population.

Defective cerebellar control of cortical plasticity in writer’s cramp

PubMed Central

Hubsch, Cecile; Roze, Emmanuel; Popa, Traian; Russo, Margherita; Balachandran, Ammu; Pradeep, Salini; Mueller, Florian; Brochard, Vanessa; Quartarone, Angelo; Degos, Bertrand; Vidailhet, Marie; Kishore, Asha

2013-01-01

A large body of evidence points to a role of basal ganglia dysfunction in the pathophysiology of dystonia, but recent studies indicate that cerebellar dysfunction may also be involved. The cerebellum influences sensorimotor adaptation by modulating sensorimotor plasticity of the primary motor cortex. Motor cortex sensorimotor plasticity is maladaptive in patients with writer’s cramp. Here we examined whether putative cerebellar dysfunction in dystonia is linked to these patients’ maladaptive plasticity. To that end we compared the performances of patients and healthy control subjects in a reaching task involving a visuomotor conflict generated by imposing a random deviation (−40° to 40°) on the direction of movement of the mouse/cursor. Such a task is known to involve the cerebellum. We also compared, between patients and healthy control subjects, how the cerebellum modulates the extent and duration of an ongoing sensorimotor plasticity in the motor cortex. The cerebellar cortex was excited or inhibited by means of repeated transcranial magnetic stimulation before artificial sensorimotor plasticity was induced in the motor cortex by paired associative stimulation. Patients with writer’s cramp were slower than the healthy control subjects to reach the target and, after having repeatedly adapted their trajectories to the deviations, they were less efficient than the healthy control subjects to perform reaching movement without imposed deviation. It was interpreted as impaired washing-out abilities. In healthy subjects, cerebellar cortex excitation prevented the paired associative stimulation to induce a sensorimotor plasticity in the primary motor cortex, whereas cerebellar cortex inhibition led the paired associative stimulation to be more efficient in inducing the plasticity. In patients with writer’s cramp, cerebellar cortex excitation and inhibition were both ineffective in modulating sensorimotor plasticity. In patients with writer’s cramp, but not in healthy subjects, behavioural parameters reflecting their capacity for adapting to the rotation and for washing-out of an earlier adaptation predicted the efficacy of inhibitory cerebellar conditioning to influence sensorimotor plasticity: the better the online adaptation, the smaller the influence of cerebellar inhibitory stimulation on motor cortex plasticity. Altered cerebellar encoding of incoming afferent volleys may result in decoupling the motor component from the afferent information flow, and also in maladjusted sensorimotor calibration. The loss of cerebellar control over sensorimotor plasticity might also lead to building up an incorrect motor program to specific adaptation tasks such as writing. PMID:23801734

Non-stationarity and power spectral shifts in EMG activity reflect motor unit recruitment in rat diaphragm muscle.

PubMed

Seven, Yasin B; Mantilla, Carlos B; Zhan, Wen-Zhi; Sieck, Gary C

2013-01-15

We hypothesized that a shift in diaphragm muscle (DIAm) EMG power spectral density (PSD) to higher frequencies reflects recruitment of more fatigable fast-twitch motor units and motor unit recruitment is reflected by EMG non-stationarity. DIAm EMG was recorded in anesthetized rats during eupnea, hypoxia-hypercapnia (10% O(2)-5% CO(2)), airway occlusion, and sneezing (maximal DIAm force). Although power in all frequency bands increased progressively across motor behaviors, PSD centroid frequency increased only during sneezing (p<0.05). The non-stationary period at the onset of EMG activity ranged from ∼80 ms during airway occlusion to ∼150 ms during eupnea. Within the initial non-stationary period of EMG activity 80-95% of motor units were recruited during different motor behaviors. Motor units augmented their discharge frequencies progressively beyond the non-stationary period; yet, EMG signal became stationary. In conclusion, non-stationarity of DIAm EMG reflects the period of motor unit recruitment, while a shift in the PSD towards higher frequencies reflects recruitment of more fatigable fast-twitch motor units. Copyright © 2012 Elsevier B.V. All rights reserved.

Speed of the bacterial flagellar motor near zero load depends on the number of stator units.

PubMed

Nord, Ashley L; Sowa, Yoshiyuki; Steel, Bradley C; Lo, Chien-Jung; Berry, Richard M

2017-10-31

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque-speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na + - and H + -driven motors. We measure the full torque-speed relationship of one and two H + units in Escherichia coli by selecting the number of H + units and controlling the number of Na + units in hybrid motors. These experiments confirm that speed near zero torque in H + -driven motors increases with the stator number. We also measured 75 torque-speed curves for Na + -driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque-speed curves to be collapsed onto a single curve by simple rescaling. Published under the PNAS license.

Isometric contractions of motor units and immunohistochemistry of mouse soleus muscle.

PubMed Central

Lewis, D M; Parry, D J; Rowlerson, A

1982-01-01

1. Isometric contractions of motor units, isolated functionally by ventral root splitting in vivo, were recorded from mouse soleus muscle. 2. Motor unit tensions varied over a narrow symmetrical range and averaged 4.7% of whole muscle tension, corresponding to twenty-one motor units per muscle. 3. There was considerable variation between muscles in isometric twitch times-to-peak and even greater variation for the motor units. The distribution of motor unit times-to-peak was apparently unimodal and could be fitted by a single normal population. A slightly better fit was, however, obtained with two normal populations, as suggested by the histochemistry. 4. Twitch time-to-peak decreased in proportion to axonal conduction velocity in individual animals. The whole population of motor units could be fitted by a linear relation between time-to-peak and the reciprocal of conduction time in the motor axon. Motor unit tension was also linearly related to the reciprocal of conduction time. 5. Histochemistry showed clear division between Type I and Type IIa fibres. Type I fibres reacted strongly with antibody against slow myosin of cat soleus muscle; Type IIa gave a reaction no stronger than the background. The division was as clear as in the cat or rat. Images Fig. 2 Plate 1 PMID:7050345

Speed of the bacterial flagellar motor near zero load depends on the number of stator units

PubMed Central

Nord, Ashley L.; Sowa, Yoshiyuki; Steel, Bradley C.; Lo, Chien-Jung; Berry, Richard M.

2017-01-01

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque–speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na+- and H+-driven motors. We measure the full torque–speed relationship of one and two H+ units in Escherichia coli by selecting the number of H+ units and controlling the number of Na+ units in hybrid motors. These experiments confirm that speed near zero torque in H+-driven motors increases with the stator number. We also measured 75 torque–speed curves for Na+-driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque–speed curves to be collapsed onto a single curve by simple rescaling. PMID:29078322

Animal models of the non-motor features of Parkinson’s disease

PubMed Central

McDowell, Kimberly; Chesselet, Marie-Françoise

2012-01-01

The non-motor symptoms (NMS) of Parkinson’s disease (PD) occur in roughly 90% of patients, have a profound negative impact on their quality of life, and often go undiagnosed. NMS typically involve many functional systems, and include sleep disturbances, neuropsychiatric and cognitive deficits, and autonomic and sensory dysfunction. The development and use of animal models have provided valuable insight into the classical motor symptoms of PD over the past few decades. Toxin-induced models provide a suitable approach to study aspects of the disease that derive from the loss of nigrostriatal dopaminergic neurons, a cardinal feature of PD. This also includes some NMS, primarily cognitive dysfunction. However, several NMS poorly respond to dopaminergic treatments, suggesting that they may be due to other pathologies. Recently developed genetic models of PD are providing new ways to model these NMS and identify their mechanisms. This review summarizes the current available literature on the ability of both toxin-induced and genetically-based animal models to reproduce the NMS of PD. PMID:22236386

Hierarchical control of motor units in voluntary contractions.

PubMed

De Luca, Carlo J; Contessa, Paola

2012-01-01

For the past five decades there has been wide acceptance of a relationship between the firing rate of motor units and the afterhyperpolarization of motoneurons. It has been promulgated that the higher-threshold, larger-soma, motoneurons fire faster than the lower-threshold, smaller-soma, motor units. This relationship was based on studies on anesthetized cats with electrically stimulated motoneurons. We questioned its applicability to motor unit control during voluntary contractions in humans. We found that during linearly force-increasing contractions, firing rates increased as exponential functions. At any time and force level, including at recruitment, the firing rate values were inversely related to the recruitment threshold of the motor unit. The time constants of the exponential functions were directly related to the recruitment threshold. From the Henneman size principle it follows that the characteristics of the firing rates are also related to the size of the soma. The "firing rate spectrum" presents a beautifully simple control scheme in which, at any given time or force, the firing rate value of earlier-recruited motor units is greater than that of later-recruited motor units. This hierarchical control scheme describes a mechanism that provides an effective economy of force generation for the earlier-recruited lower force-twitch motor units, and reduces the fatigue of later-recruited higher force-twitch motor units-both characteristics being well suited for generating and sustaining force during the fight-or-flight response.

Central Motor Conduction Studies and Diagnostic Magnetic Resonance Imaging in Children with Severe Primary and Secondary Dystonia

ERIC Educational Resources Information Center

McClelland, Verity; Mills, Kerry; Siddiqui, Ata; Selway, Richard; Lin, Jean-Pierre

2011-01-01

Aim: Dystonia in childhood has many causes. Imaging may suggest corticospinal tract dysfunction with or without coexistent basal ganglia damage. There are very few published neurophysiological studies on children with dystonia; one previous study has focused on primary dystonia. We investigated central motor conduction in 62 children (34 males, 28…

An Investigation of an Evaluation Method and Retraining Procedures for Emotionally Handicapped Children with Cognitive-Motor Deficits. Final Report.

ERIC Educational Resources Information Center

Rubin, Eli Z.; And Others

To assess the effects of specialized retraining of cognitive, perceptual, and motor (CPM) deficits, a battery of tests was prepared and used with 200 behaviorally maladjusted and 200 problem-free children. The composite score indicated that 40% of the maladjusted group manifested major dysfunction whereas none of the problem-free group…

Neural Correlates of Motor Dysfunction in Children with Traumatic Brain Injury: Exploration of Compensatory Recruitment Patterns

ERIC Educational Resources Information Center

Caeyenberghs, K.; Wenderoth, N.; Smits-Engelsman, B. C. M.; Sunaert, S.; Swinnen, S. P.

2009-01-01

Traumatic brain injury (TBI) is a common form of disability in children. Persistent deficits in motor control have been documented following TBI but there has been less emphasis on changes in functional cerebral activity. In the present study, children with moderate to severe TBI (n = 9) and controls (n = 17) were scanned while performing cyclical…

Risk Factors for Gross Motor Dysfunction in Infants with Congenital Heart Disease

ERIC Educational Resources Information Center

Long, Suzanne H.; Eldridge, Bev J.; Galea, Mary P.; Harris, Susan R.

2011-01-01

Infants with congenital heart disease (CHD) that is severe enough to require early surgery are at risk for cognitive and motor delays, as well as musculoskeletal impairments, and are best managed by an interdisciplinary team during their hospital stay and after discharge. The purpose of this article is to review some of the risk factors associated…

Metabolic Dysfunctions in Amyotrophic Lateral Sclerosis Pathogenesis and Potential Metabolic Treatments

PubMed Central

Tefera, Tesfaye W.; Borges, Karin

2017-01-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease primarily characterized by loss of motor neurons in brain and spinal cord. The death of motor neurons leads to denervation of muscle which in turn causes muscle weakness and paralysis, decreased respiratory function and eventually death. Growing evidence indicates disturbances in energy metabolism in patients with ALS and animal models of ALS, which are likely to contribute to disease progression. Particularly, defects in glucose metabolism and mitochondrial dysfunction limit the availability of ATP to CNS tissues and muscle. Several metabolic approaches improving mitochondrial function have been investigated in vitro and in vivo and showed varying effects in ALS. The effects of metabolic approaches in ALS models encompass delays in onset of motor symptoms, protection of motor neurons and extension of survival, which signifies an important role of metabolism in the pathogenesis of the disease. There is now an urgent need to test metabolic approaches in controlled clinical trials. In addition, more detailed studies to better characterize the abnormalities in energy metabolism in patients with ALS and ALS models are necessary to develop metabolically targeted effective therapies that can slow the progression of the disease and prolong life for patients with ALS. PMID:28119559

Motor and sensory function of the esophagus: revelations through ultrasound imaging.

PubMed

Mittal, Ravinder K

2005-04-01

Catheter based high frequency intraluminal ultrasound (HFIUS) imaging is a powerful tool to study esophageal sensory and motor function and dysfunction in vivo in humans. It has provided a number of important insights into the longitudinal muscle function of the esophagus. Based on the ultrasound images and intraluminal pressure recordings, it is clear that there is synchrony in the timing as well as the amplitude of contraction between the circular and the longitudinal muscle layers of the esophagus in normal subjects. On the other hand, in patients with spastic disorders of the esophagus, there is an asynchrony of contraction related to the timing and amplitude of contraction of the two muscle layers during peristalsis. Achalasia, diffuse esophageal spasm, and nutcracker esophagus (spastic motor disorders of the esophagus) are associated with hypertrophy of the circular as well as longitudinal muscle layers. A sustained contraction of the longitudinal muscle of the esophagus is temporally related to chest pain and heartburn and may very well be the cause of symptoms. Longitudinal muscle function of the esophagus can be studied in vivo in humans using dynamic ultrasound imaging. Longitudinal muscle dysfunction appears to be important in the motor and sensory disorders of the esophagus.

Subacute motor neuron hyperexcitability with mercury poisoning: a case series and literature review.

PubMed

Zhou, Zhibin; Zhang, Xingwen; Cui, Fang; Liu, Ruozhuo; Dong, Zhao; Wang, Xiaolin; Yu, Shengyuan

2014-01-01

Motor neuron hyperexcitability (MNH) indicates a disorder characterized by an ectopic motor nerve discharge on electromyogram (EMG). Here, we present a series of three cases of subacute MNH with mercury poisoning. The first case showed hyperhidrosis, insomnia, generalied myokymia, cramps, tremor, weight loss, and myokymic and neuromyotonic discharges, followed by encephalopathy with confusion, hallucinations, and memory decrease. The second case was similar to the former but without encephalopathic features. The third case showed widespread fasciculation, fatigue, insomnia, weight loss, and autonomic dysfunction, including constipation, micturition difficulty, and impotence, with multiple fibrillation, unstable fasciculation, widened motor neuron potential, and an incremental response at high-rate stimulation in repetitive nerve stimulation. Based on the symptoms, the three cases were diagnosed as Morvan's syndrome, Isaacs' syndrome, and Lambert-Eaton myasthenic syndrome with ALS-like syndrome, respectively. Mercury poisoning in the three cases was confirmed by analysis of blood and urine samples. All cases recovered several months after chelation therapy and were in good condition at follow-up. Very few cases of MNH linked with mercury exposure have been reported in the literature. The mechanism of mercury-induced MNH may be associated with ion channel dysfunction. © 2014 S. Karger AG, Basel.

Optogenetic approaches to evaluate striatal function in animal models of Parkinson disease.

PubMed

Parker, Krystal L; Kim, Youngcho; Alberico, Stephanie L; Emmons, Eric B; Narayanan, Nandakumar S

2016-03-01

Optogenetics refers to the ability to control cells that have been genetically modified to express light-sensitive ion channels. The introduction of optogenetic approaches has facilitated the dissection of neural circuits. Optogenetics allows for the precise stimulation and inhibition of specific sets of neurons and their projections with fine temporal specificity. These techniques are ideally suited to investigating neural circuitry underlying motor and cognitive dysfunction in animal models of human disease. Here, we focus on how optogenetics has been used over the last decade to probe striatal circuits that are involved in Parkinson disease, a neurodegenerative condition involving motor and cognitive abnormalities resulting from degeneration of midbrain dopaminergic neurons. The precise mechanisms underlying the striatal contribution to both cognitive and motor dysfunction in Parkinson disease are unknown. Although optogenetic approaches are somewhat removed from clinical use, insight from these studies can help identify novel therapeutic targets and may inspire new treatments for Parkinson disease. Elucidating how neuronal and behavioral functions are influenced and potentially rescued by optogenetic manipulation in animal models could prove to be translatable to humans. These insights can be used to guide future brain-stimulation approaches for motor and cognitive abnormalities in Parkinson disease and other neuropsychiatric diseases.

Small Molecule Suppressors of Drosophila Kinesin Deficiency Rescue Motor Axon Development in a Zebrafish Model of Spinal Muscular Atrophy

PubMed Central

Gassman, Andrew; Hao, Le T.; Bhoite, Leena; Bradford, Chad L.; Chien, Chi-Bin; Beattie, Christine E.; Manfredi, John P.

2013-01-01

Proximal spinal muscular atrophy (SMA) is the most common inherited motor neuropathy and the leading hereditary cause of infant mortality. Currently there is no effective treatment for the disease, reflecting a need for pharmacologic interventions that restore performance of dysfunctional motor neurons or suppress the consequences of their dysfunction. In a series of assays relevant to motor neuron biology, we explored the activities of a collection of tetrahydroindoles that were reported to alter the metabolism of amyloid precursor protein (APP). In Drosophila larvae the compounds suppressed aberrant larval locomotion due to mutations in the Khc and Klc genes, which respectively encode the heavy and light chains of kinesin-1. A representative compound of this class also suppressed the appearance of axonal swellings (alternatively termed axonal spheroids or neuritic beads) in the segmental nerves of the kinesin-deficient Drosophila larvae. Given the importance of kinesin-dependent transport for extension and maintenance of axons and their growth cones, three members of the class were tested for neurotrophic effects on isolated rat spinal motor neurons. Each compound stimulated neurite outgrowth. In addition, consistent with SMA being an axonopathy of motor neurons, the three axonotrophic compounds rescued motor axon development in a zebrafish model of SMA. The results introduce a collection of small molecules as pharmacologic suppressors of SMA-associated phenotypes and nominate specific members of the collection for development as candidate SMA therapeutics. More generally, the results reinforce the perception of SMA as an axonopathy and suggest novel approaches to treating the disease. PMID:24023935

Effects of different frequencies of repetitive transcranial magnetic stimulation on the recovery of upper limb motor dysfunction in patients with subacute cerebral infarction.

PubMed

Li, Jiang; Meng, Xiang-Min; Li, Ru-Yi; Zhang, Ru; Zhang, Zheng; Du, Yi-Feng

2016-10-01

Studies have confirmed that low-frequency repetitive transcranial magnetic stimulation can decrease the activity of cortical neurons, and high-frequency repetitive transcranial magnetic stimulation can increase the excitability of cortical neurons. However, there are few studies concerning the use of different frequencies of repetitive transcranial magnetic stimulation on the recovery of upper-limb motor function after cerebral infarction. We hypothesized that different frequencies of repetitive transcranial magnetic stimulation in patients with cerebral infarction would produce different effects on the recovery of upper-limb motor function. This study enrolled 127 patients with upper-limb dysfunction during the subacute phase of cerebral infarction. These patients were randomly assigned to three groups. The low-frequency group comprised 42 patients who were treated with 1 Hz repetitive transcranial magnetic stimulation on the contralateral hemisphere primary motor cortex (M1). The high-frequency group comprised 43 patients who were treated with 10 Hz repetitive transcranial magnetic stimulation on ipsilateral M1. Finally, the sham group comprised 42 patients who were treated with 10 Hz of false stimulation on ipsilateral M1. A total of 135 seconds of stimulation was applied in the sham group and high-frequency group. At 2 weeks after treatment, cortical latency of motor-evoked potentials and central motor conduction time were significantly lower compared with before treatment. Moreover, motor function scores were significantly improved. The above indices for the low- and high-frequency groups were significantly different compared with the sham group. However, there was no significant difference between the low- and high-frequency groups. The results show that low- and high-frequency repetitive transcranial magnetic stimulation can similarly improve upper-limb motor function in patients with cerebral infarction.

75 FR 26794 - New United Motor Manufacturing, Inc., Formerly a Joint Venture of General Motors Corporation and...

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2010-05-12

... Manufacturing, Inc., Formerly a Joint Venture of General Motors Corporation and Toyota Motor Corporation... United Motor Manufacturing, Inc., formerly a joint venture of General Motors Corporation and Toyota Motor... reviewed the certification for workers of the subject firm. The workers assemble the Toyota Corolla and the...

Motor unit behaviour and contractile changes during fatigue in the human first dorsal interosseus

PubMed Central

Carpentier, Alain; Duchateau, Jacques; Hainaut, Karl

2001-01-01

In 67 single motor units, the mechanical properties, the recruitment and derecruitment thresholds, and the discharge rates were recorded concurrently in the first dorsal interosseus (FDI) of human subjects during intermittent fatiguing contractions. The task consisted of isometric ramp-and-hold contractions performed at 50% of the maximal voluntary contraction (MVC). The purpose of this study was to examine the influence of fatigue on the behaviour of motor units with a wide range of activation thresholds. For low-threshold (< 25% MVC) motor units, the mean twitch force increased with fatigue and the recruitment threshold either did not change or increased. In contrast, the twitch force and the activation threshold decreased for the high-threshold (> 25% MVC) units. The observation that in low-threshold motor units a quick stretch of the muscle at the end of the test reset the unit force and recruitment threshold to the prefatigue value suggests a significant role for fatigue-related changes in muscle stiffness but not twitch potentiation or motor unit synchronization. Although the central drive intensified during the fatigue test, as indicated by an increase in surface electromyogram (EMG), the discharge rate of the motor units during the hold phase of each contraction decreased progressively over the course of the task for motor units that were recruited at the beginning of the test, especially the low-threshold units. In contrast, the discharge rates of newly activated units first increased and then decreased. Such divergent behaviour of low- and high-threshold motor units could not be individually controlled by the central drive to the motoneurone pool. Rather, the different behaviours must be the consequence of variable contributions from motoneurone adaptation and afferent feedback from the muscle during the fatiguing contraction. PMID:11483719

Neuropsychological function in children with primary complex motor stereotypies.

PubMed

Mahone, E Mark; Ryan, Matthew; Ferenc, Lisa; Morris-Berry, Christina; Singer, Harvey S

2014-10-01

Complex motor stereotypies (CMS) are patterned, repetitive, rhythmic, and involuntary movements that persist over time. They are divided into two subgroups dependent on the presence of other developmental problems: 'primary' (development is otherwise typical) or 'secondary' (associated with autism, intellectual disability, or sensory deficits). There are no currently published studies that examine neuropsychological function in children with primary CMS. This case-control study examines whether children with primary CMS manifest neurobehavioral deficits. Fifty-seven children with primary CMS (32 males, 25 females; mean age 6y 8mo, SD 2y 4mo, range 4-12y) with negative screens for autism and 57 comparison participants (32 males, 25 females; mean age 6y 6mo, SD 2y 1mo) completed neuropsychological assessments of IQ, reading ability, attention, language, and motor and executive functions. Parents completed ratings of their child's repetitive movement severity. The CMS group performed significantly less well than comparison participants on motor skills and IQ tests (both p<0.01), although IQ was consistently in the average range. One-third of the CMS group showed signs of developmental motor coordination difficulties. Parent report of stereotypy severity was significantly associated with parent report of inattention and executive dysfunction. Children with primary CMS were found to have largely intact neuropsychological profiles. Stereotypy severity appears to be associated with executive dysfunction. Although motor difficulties were observed in children with CMS, these were not correlated with parent report of symptom severity. © 2014 Mac Keith Press.

Effect of age and gender on the number of motor units in healthy subjects estimated by the multipoint incremental MUNE method.

PubMed

Gawel, Malgorzata; Kostera-Pruszczyk, Anna

2014-06-01

Motor unit number estimation (MUNE) is a tool for estimating the number of motor units. The aim was to evaluate the multipoint incremental MUNE method in a healthy population, to analyze whether aging, gender, and the dominant hand side influence the motor unit number, and to assess reproducibility of MUNE with the Shefner modification. We studied 60 volunteers (mean age, 47 ± 17.7 years) in four groups aged 18 to 30, 31 to 45, 46 to 60, and above 60 years. Motor unit number estimation was calculated in the abductor pollicis brevis (APB) and the abductor digiti minimi (ADM) by dividing the single motor unit action potential amplitude into the maximal compound motor action potential amplitude. Test-retest variability was 7%. The mean value of MUNE for APB was 133.2 ± 43 and for ADM was 157.1 ± 39.4. Significant differences in MUNE results were found between groups aged 18 to 30 and 60 years or older and between groups aged 31 to 45 and 60 years or older. Motor unit number estimation results correlated negatively with the age of subjects for both APB and ADM. Single motor unit action potential, reflecting the size of motor unit, increased with the age of subjects only in APB. Compound motor action potential amplitude correlated negatively with the age of subjects in APB and ADM. Significant correlations were seen between MUNE in APB or ADM and compound motor action potential amplitude in these muscles and the age of female subjects. A similar relationship was not found in males. Multipoint incremental MUNE method with the Shefner modification is a noninvasive, easy to perform method with high reproducibility. The loss of motor neurons because of aging could be confirmed by our MUNE study and seems to be more pronounced in females.

Bladder, bowel, and sexual dysfunction in Parkinson's disease.

PubMed

Sakakibara, Ryuji; Kishi, Masahiko; Ogawa, Emina; Tateno, Fuyuki; Uchiyama, Tomoyuki; Yamamoto, Tatsuya; Yamanishi, Tomonori

2011-01-01

Bladder dysfunction (urinary urgency/frequency), bowel dysfunction (constipation), and sexual dysfunction (erectile dysfunction) (also called "pelvic organ" dysfunctions) are common nonmotor disorders in Parkinson's disease (PD). In contrast to motor disorders, pelvic organ autonomic dysfunctions are often nonresponsive to levodopa treatment. The brain pathology causing the bladder dysfunction (appearance of overactivity) involves an altered dopamine-basal ganglia circuit, which normally suppresses the micturition reflex. By contrast, peripheral myenteric pathology causing slowed colonic transit (loss of rectal contractions) and central pathology causing weak strain and paradoxical anal sphincter contraction on defecation (PSD, also called as anismus) are responsible for the bowel dysfunction. In addition, hypothalamic dysfunction is mostly responsible for the sexual dysfunction (decrease in libido and erection) in PD, via altered dopamine-oxytocin pathways, which normally promote libido and erection. The pathophysiology of the pelvic organ dysfunction in PD differs from that in multiple system atrophy; therefore, it might aid in differential diagnosis. Anticholinergic agents are used to treat bladder dysfunction in PD, although these drugs should be used with caution particularly in elderly patients who have cognitive decline. Dietary fibers, laxatives, and "prokinetic" drugs such as serotonergic agonists are used to treat bowel dysfunction in PD. Phosphodiesterase inhibitors are used to treat sexual dysfunction in PD. These treatments might be beneficial in maximizing the patients' quality of life.

Bladder, Bowel, and Sexual Dysfunction in Parkinson's Disease

PubMed Central

Sakakibara, Ryuji; Kishi, Masahiko; Ogawa, Emina; Tateno, Fuyuki; Uchiyama, Tomoyuki; Yamamoto, Tatsuya; Yamanishi, Tomonori

2011-01-01

Bladder dysfunction (urinary urgency/frequency), bowel dysfunction (constipation), and sexual dysfunction (erectile dysfunction) (also called “pelvic organ” dysfunctions) are common nonmotor disorders in Parkinson's disease (PD). In contrast to motor disorders, pelvic organ autonomic dysfunctions are often nonresponsive to levodopa treatment. The brain pathology causing the bladder dysfunction (appearance of overactivity) involves an altered dopamine-basal ganglia circuit, which normally suppresses the micturition reflex. By contrast, peripheral myenteric pathology causing slowed colonic transit (loss of rectal contractions) and central pathology causing weak strain and paradoxical anal sphincter contraction on defecation (PSD, also called as anismus) are responsible for the bowel dysfunction. In addition, hypothalamic dysfunction is mostly responsible for the sexual dysfunction (decrease in libido and erection) in PD, via altered dopamine-oxytocin pathways, which normally promote libido and erection. The pathophysiology of the pelvic organ dysfunction in PD differs from that in multiple system atrophy; therefore, it might aid in differential diagnosis. Anticholinergic agents are used to treat bladder dysfunction in PD, although these drugs should be used with caution particularly in elderly patients who have cognitive decline. Dietary fibers, laxatives, and “prokinetic” drugs such as serotonergic agonists are used to treat bowel dysfunction in PD. Phosphodiesterase inhibitors are used to treat sexual dysfunction in PD. These treatments might be beneficial in maximizing the patients' quality of life. PMID:21918729

Muscle vibration sustains motor unit firing rate during submaximal isometric fatigue in humans

PubMed Central

Griffin, L; Garland, S J; Ivanova, T; Gossen, E R

2001-01-01

In keeping with the ‘muscular wisdom hypothesis’, many studies have documented that the firing rate of the majority of motor units decreased during fatiguing isometric contractions. The present study investigated whether the application of periodic muscle vibration, which strongly activates muscle spindles, would alter the modulation of motor unit firing rate during submaximal fatiguing isometric contractions. Thirty-three motor units from the lateral head of the triceps brachii muscle were recorded from 10 subjects during a sustained isometric 20 % maximal voluntary contraction (MVC) of the elbow extensors. Vibration was interposed on the contraction for 2 s every 10 s. Twenty-two motor units were recorded from the beginning of the fatigue task. The discharge rate of the majority of motor units remained constant (12/22) or increased (4/22) with fatigue. Six motor units demonstrated a reduction in discharge rate that later returned toward initial values; these motor units had higher initial discharge rates than the other 16 motor units. In a second series of experiments, four subjects held a sustained isometric 20 % MVC for 2 min and then vibration was applied as above for the remainder of the contraction. In this case, motor units initially demonstrated a decrease in firing rate that increased after the vibration was applied. Thus muscle spindle disfacilitation of the motoneurone pool may be associated with the decline of motor unit discharge rate observed during the first 2 min of the contraction. In a third set of experiments, seven subjects performed the main experiment on one occasion and repeated the fatigue task without vibration on a second occasion. Neither the endurance time of the fatiguing contraction nor the MVC torque following fatigue was affected by the application of vibration. This finding calls into question the applicability of the muscular wisdom hypothesis to submaximal contractions. PMID:11559785

Recruitment of faster motor units is associated with greater rates of fascicle strain and rapid changes in muscle force during locomotion

PubMed Central

Lee, Sabrina S. M.; de Boef Miara, Maria; Arnold, Allison S.; Biewener, Andrew A.; Wakeling, James M.

2013-01-01

SUMMARY Animals modulate the power output needed for different locomotor tasks by changing muscle forces and fascicle strain rates. To generate the necessary forces, appropriate motor units must be recruited. Faster motor units have faster activation–deactivation rates than slower motor units, and they contract at higher strain rates; therefore, recruitment of faster motor units may be advantageous for tasks that involve rapid movements or high rates of work. This study identified motor unit recruitment patterns in the gastrocnemii muscles of goats and examined whether faster motor units are recruited when locomotor speed is increased. The study also examined whether locomotor tasks that elicit faster (or slower) motor units are associated with increased (or decreased) in vivo tendon forces, force rise and relaxation rates, fascicle strains and/or strain rates. Electromyography (EMG), sonomicrometry and muscle-tendon force data were collected from the lateral and medial gastrocnemius muscles of goats during level walking, trotting and galloping and during inclined walking and trotting. EMG signals were analyzed using wavelet and principal component analyses to quantify changes in the EMG frequency spectra across the different locomotor conditions. Fascicle strain and strain rate were calculated from the sonomicrometric data, and force rise and relaxation rates were determined from the tendon force data. The results of this study showed that faster motor units were recruited as goats increased their locomotor speeds from level walking to galloping. Slow inclined walking elicited EMG intensities similar to those of fast level galloping but different EMG frequency spectra, indicating that recruitment of the different motor unit types depended, in part, on characteristics of the task. For the locomotor tasks and muscles analyzed here, recruitment patterns were generally associated with in vivo fascicle strain rates, EMG intensity and tendon force. Together, these data provide new evidence that changes in motor unit recruitment have an underlying mechanical basis, at least for certain locomotor tasks. PMID:22972893

Muscle vibration sustains motor unit firing rate during submaximal isometric fatigue in humans.

PubMed

Griffin, L; Garland, S J; Ivanova, T; Gossen, E R

2001-09-15

1. In keeping with the 'muscular wisdom hypothesis', many studies have documented that the firing rate of the majority of motor units decreased during fatiguing isometric contractions. The present study investigated whether the application of periodic muscle vibration, which strongly activates muscle spindles, would alter the modulation of motor unit firing rate during submaximal fatiguing isometric contractions. 2. Thirty-three motor units from the lateral head of the triceps brachii muscle were recorded from 10 subjects during a sustained isometric 20 % maximal voluntary contraction (MVC) of the elbow extensors. Vibration was interposed on the contraction for 2 s every 10 s. Twenty-two motor units were recorded from the beginning of the fatigue task. The discharge rate of the majority of motor units remained constant (12/22) or increased (4/22) with fatigue. Six motor units demonstrated a reduction in discharge rate that later returned toward initial values; these motor units had higher initial discharge rates than the other 16 motor units. 3. In a second series of experiments, four subjects held a sustained isometric 20 % MVC for 2 min and then vibration was applied as above for the remainder of the contraction. In this case, motor units initially demonstrated a decrease in firing rate that increased after the vibration was applied. Thus muscle spindle disfacilitation of the motoneurone pool may be associated with the decline of motor unit discharge rate observed during the first 2 min of the contraction. 4. In a third set of experiments, seven subjects performed the main experiment on one occasion and repeated the fatigue task without vibration on a second occasion. Neither the endurance time of the fatiguing contraction nor the MVC torque following fatigue was affected by the application of vibration. This finding calls into question the applicability of the muscular wisdom hypothesis to submaximal contractions.

Recruitment of faster motor units is associated with greater rates of fascicle strain and rapid changes in muscle force during locomotion.

PubMed

Lee, Sabrina S M; de Boef Miara, Maria; Arnold, Allison S; Biewener, Andrew A; Wakeling, James M

2013-01-15

Animals modulate the power output needed for different locomotor tasks by changing muscle forces and fascicle strain rates. To generate the necessary forces, appropriate motor units must be recruited. Faster motor units have faster activation-deactivation rates than slower motor units, and they contract at higher strain rates; therefore, recruitment of faster motor units may be advantageous for tasks that involve rapid movements or high rates of work. This study identified motor unit recruitment patterns in the gastrocnemii muscles of goats and examined whether faster motor units are recruited when locomotor speed is increased. The study also examined whether locomotor tasks that elicit faster (or slower) motor units are associated with increased (or decreased) in vivo tendon forces, force rise and relaxation rates, fascicle strains and/or strain rates. Electromyography (EMG), sonomicrometry and muscle-tendon force data were collected from the lateral and medial gastrocnemius muscles of goats during level walking, trotting and galloping and during inclined walking and trotting. EMG signals were analyzed using wavelet and principal component analyses to quantify changes in the EMG frequency spectra across the different locomotor conditions. Fascicle strain and strain rate were calculated from the sonomicrometric data, and force rise and relaxation rates were determined from the tendon force data. The results of this study showed that faster motor units were recruited as goats increased their locomotor speeds from level walking to galloping. Slow inclined walking elicited EMG intensities similar to those of fast level galloping but different EMG frequency spectra, indicating that recruitment of the different motor unit types depended, in part, on characteristics of the task. For the locomotor tasks and muscles analyzed here, recruitment patterns were generally associated with in vivo fascicle strain rates, EMG intensity and tendon force. Together, these data provide new evidence that changes in motor unit recruitment have an underlying mechanical basis, at least for certain locomotor tasks.

Hierarchical control of motor units in voluntary contractions

PubMed Central

Contessa, Paola

2012-01-01

For the past five decades there has been wide acceptance of a relationship between the firing rate of motor units and the afterhyperpolarization of motoneurons. It has been promulgated that the higher-threshold, larger-soma, motoneurons fire faster than the lower-threshold, smaller-soma, motor units. This relationship was based on studies on anesthetized cats with electrically stimulated motoneurons. We questioned its applicability to motor unit control during voluntary contractions in humans. We found that during linearly force-increasing contractions, firing rates increased as exponential functions. At any time and force level, including at recruitment, the firing rate values were inversely related to the recruitment threshold of the motor unit. The time constants of the exponential functions were directly related to the recruitment threshold. From the Henneman size principle it follows that the characteristics of the firing rates are also related to the size of the soma. The “firing rate spectrum” presents a beautifully simple control scheme in which, at any given time or force, the firing rate value of earlier-recruited motor units is greater than that of later-recruited motor units. This hierarchical control scheme describes a mechanism that provides an effective economy of force generation for the earlier-recruited lower force-twitch motor units, and reduces the fatigue of later-recruited higher force-twitch motor units—both characteristics being well suited for generating and sustaining force during the fight-or-flight response. PMID:21975447

Multidisciplinary Interventions in Motor Neuron Disease

PubMed Central

Williams, U. E.; Philip-Ephraim, E. E.; Oparah, S. K.

2014-01-01

Motor neuron disease is a neurodegenerative disease characterized by loss of upper motor neuron in the motor cortex and lower motor neurons in the brain stem and spinal cord. Death occurs 2–4 years after the onset of the disease. A complex interplay of cellular processes such as mitochondrial dysfunction, oxidative stress, excitotoxicity, and impaired axonal transport are proposed pathogenetic processes underlying neuronal cell loss. Currently evidence exists for the use of riluzole as a disease modifying drug; multidisciplinary team care approach to patient management; noninvasive ventilation for respiratory management; botulinum toxin B for sialorrhoea treatment; palliative care throughout the course of the disease; and Modafinil use for fatigue treatment. Further research is needed in management of dysphagia, bronchial secretion, pseudobulbar affect, spasticity, cramps, insomnia, cognitive impairment, and communication in motor neuron disease. PMID:26317009

Amblyopia and Binocular Vision

PubMed Central

Birch, Eileen E.

2012-01-01

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3% to 3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia. PMID:23201436

Neural control of muscle force: indications from a simulation model

PubMed Central

Luca, Carlo J. De

2013-01-01

We developed a model to investigate the influence of the muscle force twitch on the simulated firing behavior of motoneurons and muscle force production during voluntary isometric contractions. The input consists of an excitatory signal common to all the motor units in the pool of a muscle, consistent with the “common drive” property. Motor units respond with a hierarchically structured firing behavior wherein at any time and force, firing rates are inversely proportional to recruitment threshold, as described by the “onion skin” property. Time- and force-dependent changes in muscle force production are introduced by varying the motor unit force twitches as a function of time or by varying the number of active motor units. A force feedback adjusts the input excitation, maintaining the simulated force at a target level. The simulations replicate motor unit behavior characteristics similar to those reported in previous empirical studies of sustained contractions: 1) the initial decrease and subsequent increase of firing rates, 2) the derecruitment and recruitment of motor units throughout sustained contractions, and 3) the continual increase in the force fluctuation caused by the progressive recruitment of larger motor units. The model cautions the use of motor unit behavior at recruitment and derecruitment without consideration of changes in the muscle force generation capacity. It describes an alternative mechanism for the reserve capacity of motor units to generate extraordinary force. It supports the hypothesis that the control of motoneurons remains invariant during force-varying and sustained isometric contractions. PMID:23236008

Infant and child motor development.

PubMed

Edwards, Sara L; Sarwark, John F

2005-05-01

Identifying infant and child developmental delay is a skill important for orthopaedic surgeons to master because they often are asked to distinguish between normal and abnormal movement. An emphasis has been placed on early detection and referral for intervention, which has been shown to enhance the lives of the infant or child and his or her family. Appropriate recognition of delay is necessary for referral to early intervention services, which serve to help these children overcome or improve motor dysfunction and to help families grow more confident in caring for children with special needs. We define early intervention, discuss normal and abnormal motor development, and provide useful examination tools to assess motor development.

3-D Art Tasks.

ERIC Educational Resources Information Center

Niswander, Virginia

1983-01-01

Perceptual motor dysfunctions may not allow children with learning and behavior problems to perform as most children do. A successful art activity for these children is construction using wood scraps. (SR)

Association between vestibular function and motor performance in hearing-impaired children.

PubMed

Maes, Leen; De Kegel, Alexandra; Van Waelvelde, Hilde; Dhooge, Ingeborg

2014-12-01

The clinical balance performance of normal-hearing (NH) children was compared with the balance performance of hearing-impaired (HI) children with and without vestibular dysfunction to identify an association between vestibular function and motor performance. Prospective study. Tertiary referral center. Thirty-six children (mean age, 7 yr 5 mo; range, 3 yr 8 mo-12 yr 11 mo) divided into three groups: NH children with normal vestibular responses, HI children with normal vestibular responses, and HI children with abnormal vestibular function. A vestibular test protocol (rotatory and collic vestibular evoked myogenic potential testing) in combination with three clinical balance tests (balance beam walking, one-leg hopping, one-leg stance). Clinical balance performance. HI children with abnormal vestibular test results obtained the lowest quotients of motor performance, which were significantly lower compared with the NH group (p < 0.001 for balance beam walking and one-leg stance; p = 0.003 for one-leg hopping). The balance performance of the HI group with normal vestibular responses was better in comparison with the vestibular impaired group but still significantly lower compared with the NH group (p = 0.020 for balance beam walking; p = 0.001 for one-leg stance; not significant for one-leg hopping). These results indicate an association between vestibular function and motor performance in HI children, with a more distinct motor deterioration if a vestibular impairment is superimposed to the auditory dysfunction.

Motor Skills Training Improves Sensorimotor Dysfunction and Increases Microtubule-Associated Protein 2 mRNA Expression in Rats with Intracerebral Hemorrhage.

PubMed

Tamakoshi, Keigo; Kawanaka, Kentaro; Onishi, Hideaki; Takamatsu, Yasuyuki; Ishida, Kazuto

2016-08-01

In this study, we examined the effects of motor skills training on the sensorimotor function and the expression of genes associated with synaptic plasticity after intracerebral hemorrhage (ICH) in rats. Male Wistar rats were subjected to ICH or sham operation. ICH was caused by the injection of collagenase into the left striatum. Rats were randomly assigned to no training, acrobatic training, and sham groups. The acrobatic group performed 5 types of acrobatic tasks from 4 to 28 days after surgery. The forelimb sensorimotor function was evaluated over time using forepaw grasping, forelimb placing, and postural instability tests. At 14 and 29 days after the lesion, we analyzed the mRNA expression levels of microtubule-associated protein 2 (MAP2), brain-derived neurotrophic factor, and growth-associated protein 43 in the bilateral sensorimotor cortex (forelimb area) by real-time reverse transcription-polymerase chain reaction. Motor skills training in ICH rats improved the sensorimotor dysfunction significantly from the early phase. The mRNA expression level of MAP2 was upregulated in the ipsilesional sensorimotor cortex by motor skills training at 29 days after the lesion. Our results suggest that sensorimotor functional recovery following motor skills training after ICH is promoted by dendritic growth in the ipsilesional sensorimotor cortex. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Non-Motor Symptoms of Parkinson's Disease and Their Impact on Quality of Life in a Cohort of Moroccan Patients.

PubMed

Tibar, Houyam; El Bayad, Khalil; Bouhouche, Ahmed; Ait Ben Haddou, El Hachmia; Benomar, Ali; Yahyaoui, Mohamed; Benazzouz, Abdelhamid; Regragui, Wafa

2018-01-01

Non-motor symptoms (NMSs) are a real burden in Parkinson's disease (PD). They may appear in early pre-symptomatic stage as well as throughout the disease course. However, their relationship with the deterioration of the patient's quality of life (QoL) is still under debate. This study aimed to investigate the prevalence of NMSs and their impact on the QoL in a cohort of Moroccan patients. We carried out a cross-transactional study, where a total of 117 patients were submitted to a structured clinical interview and examination investigating motor and NMSs based on common and conventional scales. Motor symptoms were assessed by the UPDRS I-VI during ON condition. The NMSs were evaluated with common scales and their relationship with the QoL was investigated. The mean patient's age was 60.77 ± 11.36 years old, and the median disease duration was 6 years [2.5-9.5]. Motor's phenotype subtypes were the mixed form in 40.2% of patients, akinetic-rigid in 20.5% and a tremor-dominant form in 39.3%. The median Hoehn and Yahr staging was 2 [1-2.5]. Regarding NMSs, the most common were urinary dysfunctions (82.6%), sleep (80.6%), and gastrointestinal (80%) disorders. Other autonomic dysfunctions were also frequent: thermoregulatory dysfunctions 58.6%, cardiovascular troubles 50.9%, and sexual dysfunctions 47.9%. Depression was present in 47.9% and fatigue symptoms in 23.1%. The median score of SCOPA-AUT was 14 [7.75-21.80]. The median PD questionnaire 39-score index (PDQ39-SI) was 23.22% and the most affected dimension was "mobility." Univariate and multivariate analyses showed that the SCOPA-AUT score impacted the QoL ( p  = 0.001), especially the gastrointestinal ( p  = 0.007), and cardiovascular ( p  = 0.049) dimensions. Our data show that all patients have presented at least one NMS. Autonomic and sleep disorders were the most frequent, and in contrast to other studies, digestive and cardiovascular disorders were rather the factors influencing negatively the QoL of patients. Understanding the pathophysiology of these NMSs should be placed at the forefront in order to develop new therapeutic approaches by improving the QoL of PD patients.

Motor Controller System For Large Dynamic Range of Motor Operation

NASA Technical Reports Server (NTRS)

Howard, David E. (Inventor); Alhorn, Dean C. (Inventor); Smith, Dennis A. (Inventor); Dutton, Kenneth R. (Inventor); Paulson, Mitchell Scott (Inventor)

2006-01-01

A motor controller system uses a rotary sensor with a plurality of signal conditioning units, coupled to the rotary sensor. Each of these units, which is associated with a particular range of motor output shaft rotation rates, generate a feedback signal indicative of the position of the motor s output shaft. A controller (i) converts a selected motor output shaft rotation rate to a corresponding incremental amount of rotational movement for a selected fixed time period, (ii) selects, at periodic completions of the selected fixed time period, the feedback signal from one of the signal conditioning units for which the particular range of motor output shaft rotation rates associated therewith encompasses the selected motor output shaft rotation rate, and (iii) generates a motor drive signal based on a difference between the incremental amount of rotational movement and the feedback signal from the selected one of the signal conditioning Units.

Motor unit recruitment and bursts of activity in the surface electromyogram during a sustained contraction.

PubMed

Riley, Zachary A; Terry, Mary E; Mendez-Villanueva, Alberto; Litsey, Jane C; Enoka, Roger M

2008-06-01

Bursts of activity in the surface electromyogram (EMG) during a sustained contraction have been interpreted as corresponding to the transient recruitment of motor units, but this association has never been confirmed. The current study compared the timing of trains of action potentials discharged by single motor units during a sustained contraction with the bursts of activity detected in the surface EMG signal. The 20 motor units from 6 subjects [recruitment threshold, 35.3 +/- 11.3% maximal voluntary contraction (MVC) force] that were detected with fine wire electrodes discharged 2-9 trains of action potentials (7.2 +/- 5.6 s in duration) when recruited during a contraction that was sustained at a force below its recruitment threshold (target force, 25.4 +/- 10.6% MVC force). High-pass filtering the bipolar surface EMG signal improved its correlation with the single motor unit signal. An algorithm applied to the surface EMG was able to detect 75% of the trains of motor unit action potentials. The results indicate that bursts of activity in the surface EMG during a constant-force contraction correspond to the transient recruitment of higher-threshold motor units in healthy individuals, and these results could assist in the diagnosis and design of treatment in individuals who demonstrate deficits in motor unit activation.

Shifts in the relationship between motor unit recruitment thresholds versus derecruitment thresholds during fatigue.

PubMed

Stock, Matt S; Mota, Jacob A

2017-12-01

Muscle fatigue is associated with diminished twitch force amplitude. We examined changes in the motor unit recruitment versus derecruitment threshold relationship during fatigue. Nine men (mean age = 26 years) performed repeated isometric contractions at 50% maximal voluntary contraction (MVC) knee extensor force until exhaustion. Surface electromyographic signals were detected from the vastus lateralis, and were decomposed into their constituent motor unit action potential trains. Motor unit recruitment and derecruitment thresholds and firing rates at recruitment and derecruitment were evaluated at the beginning, middle, and end of the protocol. On average, 15 motor units were studied per contraction. For the initial contraction, three subjects showed greater recruitment thresholds than derecruitment thresholds for all motor units. Five subjects showed greater recruitment thresholds than derecruitment thresholds for only low-threshold motor units at the beginning, with a mean cross-over of 31.6% MVC. As the muscle fatigued, many motor units were derecruited at progressively higher forces. In turn, decreased slopes and increased y-intercepts were observed. These shifts were complemented by increased firing rates at derecruitment relative to recruitment. As the vastus lateralis fatigued, the central nervous system's compensatory adjustments resulted in a shift of the regression line of the recruitment versus derecruitment threshold relationship. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Development and use of the incremental twitch subtraction MUNE method in mice.

PubMed

Hegedus, Janka; Jones, Kelvin E; Gordon, Tessa

2009-01-01

We have used a technique to estimate the number of functioning motor units (MUNE) innervating a muscle in mice based on twitch tension. The MUNE technique was verified by modeling twitch tensions from isolated ventral root stimulation. Analysis by twitch tensions allowed us to identify motor unit fiber types. The MUNE technique was used to compare normal mice with transgenic superoxide dismutase-1 mutation (G94A) mice to assess the time course of motor unit loss with respect to fiber type. Motor unit loss was found to occur well in advance of behavioral changes and the degree of reinnervation is dependent upon motor unit fiber types.

Motor unit recruitment strategies are altered during deep-tissue pain.

PubMed

Tucker, Kylie; Butler, Jane; Graven-Nielsen, Thomas; Riek, Stephan; Hodges, Paul

2009-09-02

Muscle pain is associated with decreased motor unit discharge rate during constant force contractions. As discharge rate is a determinant of force, other adaptations in strategy must explain force maintenance during pain. Our aim was to determine whether motor unit recruitment strategies are altered during pain to maintain force despite reduced discharge rate. Motor unit discharge behavior was recorded in two muscles, one with (quadriceps) and one without [flexor pollicis longus (FPL)] synergists. Motor units were recruited during matched low-force contractions with and without experimentally induced pain, and at higher force without pain. A total of 52 and 34 units were recorded in quadriceps and FPL, respectively, during low-force contractions with and without pain. Of these, 20 quadriceps and 9 FPL units were identified during both trials. The discharge rate of these units reduced during pain in both muscles [quadriceps: 8.7 (1.5) to 7.5 (1.3) Hz, p < 0.001; FPL: 11.9 (1.5) to 10.0 (1.7) Hz, p < 0.001]. All remaining units discharged only with or without pain, but not in both conditions. Only one-third of the additional units recruited during pain (quadriceps n = 7/19, FPL n = 3/15) were those expected given orderly recruitment of the motor unit pool as determined during higher-force contractions. We conclude that reduced motor unit discharge rate with pain is accompanied by changes in the population of units used to maintain force. The recruitment of new units is partly inconsistent with generalized inhibition of the motoneuron pool predicted by the "pain adaptation" theory, and provides the basis for a new mechanism of motor adaptation with pain.

Relationships between motor unit size and recruitment threshold in older adults: implications for size principle.

PubMed

Fling, Brett W; Knight, Christopher A; Kamen, Gary

2009-08-01

As a part of the aging process, motor unit reorganization occurs in which small motoneurons reinnervate predominantly fast-twitch muscle fibers that have lost their innervation. We examined the relationship between motor unit size and the threshold force for recruitment in two muscles to determine whether older individuals might develop an alternative pattern of motor unit activation. Young and older adults performed isometric contractions ranging from 0 to 50% of maximal voluntary contraction in both the first dorsal interosseous (FDI) and tibialis anterior (TA) muscles. Muscle fiber action potentials were recorded with an intramuscular needle electrode and motor unit size was computed using spike-triggered averaging of the global EMG signal (macro EMG), which was also obtained from the intramuscular needle electrode. As expected, older individuals exhibited larger motor units than young subjects in both the FDI and the TA. However, moderately strong correlations were obtained for the macro EMG amplitude versus recruitment threshold relationship in both the young and older adults within both muscles, suggesting that the size principle of motor unit recruitment seems to be preserved in older adults.

Task-Dependent Intermuscular Motor Unit Synchronization between Medial and Lateral Vastii Muscles during Dynamic and Isometric Squats.

PubMed

Mohr, Maurice; Nann, Marius; von Tscharner, Vinzenz; Eskofier, Bjoern; Nigg, Benno Maurus

2015-01-01

Motor unit activity is coordinated between many synergistic muscle pairs but the functional role of this coordination for the motor output is unclear. The purpose of this study was to investigate the short-term modality of coordinated motor unit activity-the synchronized discharge of individual motor units across muscles within time intervals of 5ms-for the Vastus Medialis (VM) and Lateralis (VL). Furthermore, we studied the task-dependency of intermuscular motor unit synchronization between VM and VL during static and dynamic squatting tasks to provide insight into its functional role. Sixteen healthy male and female participants completed four tasks: Bipedal squats, single-leg squats, an isometric squat, and single-leg balance. Monopolar surface electromyography (EMG) was used to record motor unit activity of VM and VL. For each task, intermuscular motor unit synchronization was determined using a coherence analysis between the raw EMG signals of VM and VL and compared to a reference coherence calculated from two desynchronized EMG signals. The time shift between VM and VL EMG signals was estimated according to the slope of the coherence phase angle spectrum. For all tasks, except for singe-leg balance, coherence between 15-80Hz significantly exceeded the reference. The corresponding time shift between VM and VL was estimated as 4ms. Coherence between 30-60Hz was highest for the bipedal squat, followed by the single-leg squat and the isometric squat. There is substantial short-term motor unit synchronization between VM and VL. Intermuscular motor unit synchronization is enhanced for contractions during dynamic activities, possibly to facilitate a more accurate control of the joint torque, and reduced during single-leg tasks that require balance control and thus, a more independent muscle function. It is proposed that the central nervous system scales the degree of intermuscular motor unit synchronization according to the requirements of the movement task at hand.

Task-Dependent Intermuscular Motor Unit Synchronization between Medial and Lateral Vastii Muscles during Dynamic and Isometric Squats

PubMed Central

Mohr, Maurice; Nann, Marius; von Tscharner, Vinzenz; Eskofier, Bjoern; Nigg, Benno Maurus

2015-01-01

Purpose Motor unit activity is coordinated between many synergistic muscle pairs but the functional role of this coordination for the motor output is unclear. The purpose of this study was to investigate the short-term modality of coordinated motor unit activity–the synchronized discharge of individual motor units across muscles within time intervals of 5ms–for the Vastus Medialis (VM) and Lateralis (VL). Furthermore, we studied the task-dependency of intermuscular motor unit synchronization between VM and VL during static and dynamic squatting tasks to provide insight into its functional role. Methods Sixteen healthy male and female participants completed four tasks: Bipedal squats, single-leg squats, an isometric squat, and single-leg balance. Monopolar surface electromyography (EMG) was used to record motor unit activity of VM and VL. For each task, intermuscular motor unit synchronization was determined using a coherence analysis between the raw EMG signals of VM and VL and compared to a reference coherence calculated from two desynchronized EMG signals. The time shift between VM and VL EMG signals was estimated according to the slope of the coherence phase angle spectrum. Results For all tasks, except for singe-leg balance, coherence between 15–80Hz significantly exceeded the reference. The corresponding time shift between VM and VL was estimated as 4ms. Coherence between 30–60Hz was highest for the bipedal squat, followed by the single-leg squat and the isometric squat. Conclusion There is substantial short-term motor unit synchronization between VM and VL. Intermuscular motor unit synchronization is enhanced for contractions during dynamic activities, possibly to facilitate a more accurate control of the joint torque, and reduced during single-leg tasks that require balance control and thus, a more independent muscle function. It is proposed that the central nervous system scales the degree of intermuscular motor unit synchronization according to the requirements of the movement task at hand. PMID:26529604

Sexuality in patients with Parkinson's disease, Alzheimer's disease, and other dementias.

PubMed

Bronner, Gila; Aharon-Peretz, Judith; Hassin-Baer, Sharon

2015-01-01

Sexual dysfunction (SD) is common among patients with Parkinson's disease (PD), Alzheimer's disease (AD), and other dementias. Sexual functioning and well-being of patients with PD and their partners are affected by many factors, including motor disabilities, non-motor symptoms (e.g., autonomic dysfunction, sleep disturbances, mood disorders, cognitive abnormalities, pain, and sensory disorders), medication effects, and relationship issues. The common sexual problems are decreased desire, erectile dysfunction, difficulties in reaching orgasm, and sexual dissatisfaction. Hypersexuality is one of a broad range of impulse control disorders reported in PD, attributed to antiparkinsonian therapy, mainly dopamine agonists. Involvement of a multidisciplinary team may enable a significant management of hypersexuality. Data on SD in demented patients are scarce, mainly reporting reduced frequency of sex and erectile dysfunction. Treatment of SD is advised at an early stage. Behavioral problems, including inappropriate sexual behavior (ISB), are distressing for patients and their caregivers and may reflect the prevailing behavior accompanying dementia (disinhibition or apathy associated with hyposexuality). The neurobiologic basis of ISB is still only vaguely understood but assessment and intervention are recommended as soon as ISB is suspected. Management of ISB in dementia demands a thorough evaluation and understanding of the behavior, and can be treated by non-pharmacologic and pharmacologic interventions. © 2015 Elsevier B.V. All rights reserved.

Design of BLDCM emulator for transmission control units

NASA Astrophysics Data System (ADS)

Liu, Chang; He, Yongyi; Zhang, Bodong

2018-04-01

According to the testing requirements of the transmission control unit, a brushless DC motor emulating system is designed based on motor simulation and power hardware-in-the-loop. The discrete motor model is established and a real-time numerical method is designed to solve the motor states. The motor emulator directly interacts with power stage of the transmission control unit using a power-efficient circuit topology and is compatible with sensor-less control. Experiments on a laboratory prototype help to verify that the system can emulate the real motor currents and voltages whenever the motor is starting up or suddenly loaded.

Behavior of motor units in human biceps brachii during a submaximal fatiguing contraction.

PubMed

Garland, S J; Enoka, R M; Serrano, L P; Robinson, G A

1994-06-01

The activity of 50 single motor units was recorded in the biceps brachii muscle of human subjects while they performed submaximal isometric elbow flexion contractions that were sustained to induce fatigue. The purposes of this study were to examine the influence of fatigue on motor unit threshold force and to determine the relationship between the threshold force of recruitment and the initial interimpulse interval on the discharge rates of single motor units during a fatiguing contraction. The discharge rate of most motor units that were active from the beginning of the contraction declined during the fatiguing contraction, whereas the discharge rates of most newly recruited units were either constant or increased slightly. The absolute threshold forces of recruitment and derecruitment decreased, and the variability of interimpulse intervals increased after the fatigue task. The change in motor unit discharge rate during the fatigue task was related to the initial rate, but the direction of the change in discharge rate could not be predicted from the threshold force of recruitment or the variability in the interimpulse intervals. The discharge rate of most motor units declined despite an increase in the excitatory drive to the motoneuron pool during the fatigue task.

Eyeblink conditioning is impaired in subjects with essential tremor.

PubMed

Kronenbuerger, Martin; Gerwig, Marcus; Brol, Beate; Block, Frank; Timmann, Dagmar

2007-06-01

Several lines of evidence point to an involvement of the olivo-cerebellar system in the pathogenesis of essential tremor (ET), with clinical signs of cerebellar dysfunction being present in some subjects in the advanced stage. Besides motor coordination, the cerebellum is critically involved in motor learning. Evidence of motor learning deficits would strengthen the hypothesis of olivo-cerebellar involvement in ET. Conditioning of the eyeblink reflex is a well-established paradigm to assess motor learning. Twenty-three ET subjects (13 males, 10 females; mean age 44.3 +/- 22.3 years, mean disease duration 17.4 +/- 17.3 years) and 23 age-matched healthy controls were studied on two consecutive days using a standard delay eyeblink conditioning protocol. Six ET subjects exhibited accompanying clinical signs of cerebellar dysfunction. Care was taken to examine subjects without medication affecting central nervous functioning. Seven ET subjects and three controls on low-dose beta-blocker treatments, which had no effect on eyeblink conditioning in animal studies, were allowed into the study. The ability to acquire conditioned eyeblink responses was significantly reduced in ET subjects compared with controls. Impairment of eyeblink conditioning was not due to low-dose beta-blocker medication. Additionally, acquisition of conditioned eyeblink response was reduced in ET subjects regardless of the presence of cerebellar signs in clinical examination. There were no differences in timing or extinction of conditioned responses between groups and conditioning deficits did not correlate with the degree of tremor or ataxia as rated by clinical scores. The findings of disordered eyeblink conditioning support the hypothesis that ET is caused by a functional disturbance of olivo-cerebellar circuits which may cause cerebellar dysfunction. In particular, results point to an involvement of the olivo-cerebellar system in early stages of ET.

Motor units in vastus lateralis and in different vastus medialis regions show different firing properties during low-level, isometric knee extension contraction.

PubMed

de Souza, Leonardo Mendes Leal; Cabral, Hélio Veiga; de Oliveira, Liliam Fernandes; Vieira, Taian Martins

2018-04-01

Architectural differences along vastus medialis (VM) and between VM and vastus lateralis (VL) are considered functionally important for the patellar tracking, knee joint stability and knee joint extension. Whether these functional differences are associated with a differential activity of motor units between VM and VL is however unknown. In the present study, we, therefore, investigate neuroanatomical differences in the activity of motor units detected proximo-distally from VM and from the VL muscle. Nine healthy volunteers performed low-level isometric knee extension contractions (20% of their maximum voluntary contraction) following a trapezoidal trajectory. Surface electromyograms (EMGs) were recorded from VM proximal and distal regions and from VL using three linear adhesive arrays of eight electrodes. The firing rate and recruitment threshold of motor units decomposed from EMGs were then compared among muscle regions. Results show that VL motor units reached lower mean firing rates in comparison with VM motor units, regardless of their position within VM (P < .040). No significant differences in firing rate were found between proximal and distal, VM motor units (P = .997). Furthermore, no significant differences in the recruitment threshold were observed for all motor units analysed (P = .108). Our findings possibly suggest the greater potential of VL to generate force, due to its fibres arrangement, may account for the lower discharge rate observed for VL then either proximally or distally detected motor units in VM. Additionally, the present study opens new perspectives on the importance of considering muscle architecture in investigations of the neural aspects of motor behaviour. Copyright © 2017 Elsevier B.V. All rights reserved.

29. SOUTH SWING SPAN, SHOWING REPRESENTATIVE REDUCTION GEAR/MOTOR DRIVE UNIT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. SOUTH SWING SPAN, SHOWING REPRESENTATIVE REDUCTION GEAR/MOTOR DRIVE UNIT (CENTER) AND WEDGE MOTOR UNIT (RIGHT). - George P. Coleman Memorial Bridge, Spanning York River at U.S. Route 17, Yorktown, York County, VA

Motor Unit Interpulse Intervals During High Force Contractions.

PubMed

Stock, Matt S; Thompson, Brennan J

2016-01-01

We examined the means, medians, and variability for motor-unit interpulse intervals (IPIs) during voluntary, high force contractions. Eight men (mean age = 22 years) attempted to perform isometric contractions at 90% of their maximal voluntary contraction force while bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis and vastus medialis muscles. Surface EMG signal decomposition was used to determine the recruitment thresholds and IPIs of motor units that demonstrated accuracy levels ≥ 96.0%. Motor units with high recruitment thresholds demonstrated longer mean IPIs, but the coefficients of variation were similar across all recruitment thresholds. Polynomial regression analyses indicated that for both muscles, the relationship between the means and standard deviations of the IPIs was linear. The majority of IPI histograms were positively skewed. Although low-threshold motor units were associated with shorter IPIs, the variability among motor units with differing recruitment thresholds was comparable.

The aging neuromuscular system and motor performance

PubMed Central

Keenan, Kevin G.

2016-01-01

Age-related changes in the basic functional unit of the neuromuscular system, the motor unit, and its neural inputs have a profound effect on motor function, especially among the expanding number of old (older than ∼60 yr) and very old (older than ∼80 yr) adults. This review presents evidence that age-related changes in motor unit morphology and properties lead to impaired motor performance that includes 1) reduced maximal strength and power, slower contractile velocity, and increased fatigability; and 2) increased variability during and between motor tasks, including decreased force steadiness and increased variability of contraction velocity and torque over repeat contractions. The age-related increase in variability of motor performance with aging appears to involve reduced and more variable synaptic inputs that drive motor neuron activation, fewer and larger motor units, less stable neuromuscular junctions, lower and more variable motor unit action potential discharge rates, and smaller and slower skeletal muscle fibers that coexpress different myosin heavy chain isoforms in the muscle of older adults. Physical activity may modify motor unit properties and function in old men and women, although the effects on variability of motor performance are largely unknown. Many studies are of cross-sectional design, so there is a tremendous opportunity to perform high-impact and longitudinal studies along the continuum of aging that determine 1) the influence and cause of the increased variability with aging on functional performance tasks, and 2) whether lifestyle factors such as physical exercise can minimize this age-related variability in motor performance in the rapidly expanding numbers of very old adults. PMID:27516536

Second-chance signal transduction explains cooperative flagellar switching.

PubMed

Zot, Henry G; Hasbun, Javier E; Minh, Nguyen Van

2012-01-01

The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv-vii).

Pathophysiology of the Gut and the Microbiome in the Host Response.

PubMed

Lyons, John D; Coopersmith, Craig M

2017-03-01

To describe and summarize the data supporting the gut as the motor driving critical illness and multiple organ dysfunction syndrome presented at the National Institute of Child Health and Human Development MODS Workshop (March 26-27, 2015). Summary of workshop keynote presentation. Not applicable. Presented by an expert in the field, the data assessing the role of gastrointestinal dysfunction driving critical illness were described with a focus on identifying knowledge gaps and research priorities. Summary of presentation and discussion supported and supplemented by relevant literature. The understanding of gut dysfunction in critical illness has evolved greatly over time, and the gut is now often considered as the "motor" of critical illness. The association of the gut with critical illness is supported by both animal models and clinical studies. Initially, the association between gut dysfunction and critical illness focused primarily on bacterial translocation into the bloodstream. However, that work has evolved to include other gut-derived products causing distant injury via other routes (e.g., lymphatics). Additionally, alterations in the gut epithelium may be associated with critical illness and influence outcomes. Gut epithelial apoptosis, intestinal hyperpermeability, and perturbations in the intestinal mucus layer have all been associated with critical illness. Finally, there is growing evidence that the intestinal microbiome plays a crucial role in mediating pathology in critical illness. Further research is needed to better understand the role of each of these mechanisms and their contribution to multiple organ dysfunction syndrome in children.

Increased Levels of Rictor Prevent Mutant Huntingtin-Induced Neuronal Degeneration.

PubMed

Creus-Muncunill, Jordi; Rué, Laura; Alcalá-Vida, Rafael; Badillos-Rodríguez, Raquel; Romaní-Aumedes, Joan; Marco, Sonia; Alberch, Jordi; Perez-Otaño, Isabel; Malagelada, Cristina; Pérez-Navarro, Esther

2018-02-19

Rictor associates with mTOR to form the mTORC2 complex, which activity regulates neuronal function and survival. Neurodegenerative diseases are characterized by the presence of neuronal dysfunction and cell death in specific brain regions such as for example Huntington's disease (HD), which is characterized by the loss of striatal projection neurons leading to motor dysfunction. Although HD is caused by the expression of mutant huntingtin, cell death occurs gradually suggesting that neurons have the capability to activate compensatory mechanisms to deal with neuronal dysfunction and later cell death. Here, we analyzed whether mTORC2 activity could be altered by the presence of mutant huntingtin. We observed that Rictor levels are specifically increased in the striatum of HD mouse models and in the putamen of HD patients. Rictor-mTOR interaction and the phosphorylation levels of Akt, one of the targets of the mTORC2 complex, were increased in the striatum of the R6/1 mouse model of HD suggesting increased mTORC2 signaling. Interestingly, acute downregulation of Rictor in striatal cells in vitro reduced mTORC2 activity, as shown by reduced levels of phospho-Akt, and increased mutant huntingtin-induced cell death. Accordingly, overexpression of Rictor increased mTORC2 activity counteracting cell death. Furthermore, normalization of endogenous Rictor levels in the striatum of R6/1 mouse worsened motor symptoms suggesting an induction of neuronal dysfunction. In conclusion, our results suggest that increased Rictor striatal levels could counteract neuronal dysfunction induced by mutant huntingtin.

Motor unit recruitment patterns 2: the influence of myoelectric intensity and muscle fascicle strain rate.

PubMed

Hodson-Tole, Emma F; Wakeling, James M

2008-06-01

To effectively meet the force requirements of a given movement an appropriate number and combination of motor units must be recruited between and within muscles. Orderly recruitment of motor units has been shown to occur in a wide range of skeletal muscles, however, alternative strategies do occur. Faster motor units are better suited to developing force rapidly, and produce higher mechanical power with greater efficiency at faster shortening strain rates than slower motor units. As the frequency content of the myoelectric signal is related to the fibre type of the active motor units, we hypothesised that, in addition to an association between myoelectric frequency and intensity, there would be a significant association between muscle fascicle shortening strain rate and myoelectric frequency content. Myoelectric and sonomicrometric data were collected from the three ankle extensor muscles of the rat hind limb during walking and running. Myoelectric signals were analysed using wavelet transformation and principal component analysis to give a measure of the signal frequency content. Sonomicrometric signals were analysed to give measures of muscle fascicle strain and strain rate. The relationship between myoelectric frequency and both intensity and muscle fascicle strain rate was found to change across the time course of a stride, with differences also occurring in the strength of the associations between and within muscles. In addition to the orderly recruitment of motor units, a mechanical strategy of motor unit recruitment was therefore identified. Motor unit recruitment is therefore a multifactorial phenomenon, which is more complex than typically thought.

Recruitment of motor units in two fascicles of the semispinalis cervicis muscle.

PubMed

Schomacher, Jochen; Dideriksen, Jakob Lund; Farina, Dario; Falla, Deborah

2012-06-01

This study investigated the behavior of motor units in the semispinalis cervicis muscle. Intramuscular EMG recordings were obtained unilaterally at levels C2 and C5 in 15 healthy volunteers (8 men, 7 women) who performed isometric neck extensions at 5%, 10%, and 20% of the maximal force [maximum voluntary contraction (MVC)] for 2 min each and linearly increasing force contractions from 0 to 30% MVC over 3 s. Individual motor unit action potentials were identified. The discharge rate and interspike interval variability of the motor units in the two locations did not differ. However, the recruitment threshold of motor units detected at C2 (n = 16, mean ± SD: 10.3 ± 6.0% MVC) was greater than that of motor units detected at C5 (n = 92, 6.9 ± 4.3% MVC) (P < 0.01). A significant level of short-term synchronization was identified in 246 of 307 motor unit pairs when computed within one spinal level but only in 28 of 110 pairs of motor units between the two levels. The common input strength, which quantifies motor unit synchronization, was greater for pairs within one level (0.47 ± 0.32) compared with pairs between levels (0.09 ± 0.07) (P < 0.05). In a second experiment on eight healthy subjects, interference EMG was recorded from the same locations during a linearly increasing force contraction from 0 to 40% MVC and showed significantly greater EMG amplitude at C5 than at C2. In conclusion, synaptic input is distributed partly independently and nonuniformly to different fascicles of the semispinalis cervicis muscle.

System and method for motor speed estimation of an electric motor

DOEpatents

Lu, Bin [Kenosha, WI; Yan, Ting [Brookfield, WI; Luebke, Charles John [Sussex, WI; Sharma, Santosh Kumar [Viman Nagar, IN

2012-06-19

A system and method for a motor management system includes a computer readable storage medium and a processing unit. The processing unit configured to determine a voltage value of a voltage input to an alternating current (AC) motor, determine a frequency value of at least one of a voltage input and a current input to the AC motor, determine a load value from the AC motor, and access a set of motor nameplate data, where the set of motor nameplate data includes a rated power, a rated speed, a rated frequency, and a rated voltage of the AC motor. The processing unit is also configured to estimate a motor speed based on the voltage value, the frequency value, the load value, and the set of nameplate data and also store the motor speed on the computer readable storage medium.

Ia Afferent input alters the recruitment thresholds and firing rates of single human motor units.

PubMed

Grande, G; Cafarelli, E

2003-06-01

Vibration of the patellar tendon recruits motor units in the knee extensors via excitation of muscle spindles and subsequent Ia afferent input to the alpha-motoneuron pool. Our first purpose was to determine if the recruitment threshold and firing rate of the same motor unit differed when recruited involuntarily via reflex or voluntarily via descending spinal pathways. Although Ia input is excitatory to the alpha-motoneuron pool, it has also been shown paradoxically to inhibit itself. Our second purpose was to determine if vibration of the patellar tendon during a voluntary knee extension causes a change in the firing rate of already recruited motor units. In the first protocol, 10 subjects voluntarily reproduced the same isometric force profile of the knee extensors that was elicited by vibration of the patellar tendon. Single motor unit recordings from the vastus lateralis (VL) were obtained with tungsten microelectrodes and unitary behaviour was examined during both reflex and voluntary knee extensions. Recordings from 135 single motor units showed that both recruitment thresholds and firing rates were lower during reflex contractions. In the second protocol, 7 subjects maintained a voluntary knee extension at 30 N for approximately 40-45 s. Three bursts of patellar tendon vibration were superimposed at regular intervals throughout the contraction and changes in the firing rate of already recruited motor units were examined. A total of 35 motor units were recorded and each burst of superimposed vibration caused a momentary reduction in the firing rates and recruitment of additional units. Our data provide evidence that Ia input modulates the recruitment thresholds and firing rates of motor units providing more flexibility within the neuromuscular system to grade force at low levels of force production.

Hemispheric Lateralization of Motor Thresholds in Relation to Stuttering

PubMed Central

Alm, Per A.; Karlsson, Ragnhild; Sundberg, Madeleine; Axelson, Hans W.

2013-01-01

Stuttering is a complex speech disorder. Previous studies indicate a tendency towards elevated motor threshold for the left hemisphere, as measured using transcranial magnetic stimulation (TMS). This may reflect a monohemispheric motor system impairment. The purpose of the study was to investigate the relative side-to-side difference (asymmetry) and the absolute levels of motor threshold for the hand area, using TMS in adults who stutter (n = 15) and in controls (n = 15). In accordance with the hypothesis, the groups differed significantly regarding the relative side-to-side difference of finger motor threshold (p = 0.0026), with the stuttering group showing higher motor threshold of the left hemisphere in relation to the right. Also the absolute level of the finger motor threshold for the left hemisphere differed between the groups (p = 0.049). The obtained results, together with previous investigations, provide support for the hypothesis that stuttering tends to be related to left hemisphere motor impairment, and possibly to a dysfunctional state of bilateral speech motor control. PMID:24146930

Discharge patterns of human genioglossus motor units during arousal from sleep.

PubMed

Wilkinson, Vanessa; Malhotra, Atul; Nicholas, Christian L; Worsnop, Christopher; Jordan, Amy S; Butler, Jane E; Saboisky, Julian P; Gandevia, Simon C; White, David P; Trinder, John

2010-03-01

Single motor unit recordings of the human genioglossus muscle reveal motor units with a variety of discharge patterns. Integrated multiunit electromyographic recordings of genioglossus have demonstrated an abrupt increase in the muscle's activity at arousal from sleep. The aim of the present study was to determine the effect of arousal from sleep on the activity of individual motor units as a function of their particular discharge pattern. Genioglossus activity was measured using intramuscular fine-wire electrodes inserted via a percutaneous approach. Arousals from sleep were identified using the ASDA criterion and the genioglossus electromyogram recordings analyzed for single motor unit activity. Sleep research laboratory. Sleep and respiratory data were collected in 8 healthy subjects (6 men). 138 motor units were identified during prearousalarousal sleep: 25% inspiratory phasic, 33% inspiratory tonic, 4% expiratory phasic, 3% expiratory tonic, and 35% tonic. At arousal from sleep inspiratory phasic units significantly increased the proportion of a breath over which they were active, but did not appreciably increase their rate of firing. 80 new units were identified at arousals, 75% were inspiratory, many of which were active for only 1 or 2 breaths. 22% of units active before arousal, particularly expiratory and tonic units, stopped at the arousal. Increased genioglossus muscle activity at arousal from sleep is primarily due to recruitment of inspiratory phasic motor units. Further, activity within the genioglossus motoneuron pool is reorganized at arousal as, in addition to recruitment, approximately 20% of units active before arousals stopped firing.

Characterizing the complexity of spontaneous motor unit patterns of amyotrophic lateral sclerosis using approximate entropy

NASA Astrophysics Data System (ADS)

Zhou, Ping; Barkhaus, Paul E.; Zhang, Xu; Zev Rymer, William

2011-10-01

This paper presents a novel application of the approximate entropy (ApEn) measurement for characterizing spontaneous motor unit activity of amyotrophic lateral sclerosis (ALS) patients. High-density surface electromyography (EMG) was used to record spontaneous motor unit activity bilaterally from the thenar muscles of nine ALS subjects. Three distinct patterns of spontaneous motor unit activity (sporadic spikes, tonic spikes and high-frequency repetitive spikes) were observed. For each pattern, complexity was characterized by calculating the ApEn values of the representative signal segments. A sliding window over each segment was also introduced to quantify the dynamic changes in complexity for the different spontaneous motor unit patterns. We found that the ApEn values for the sporadic spikes were the highest, while those of the high-frequency repetitive spikes were the lowest. There is a significant difference in mean ApEn values between two arbitrary groups of the three spontaneous motor unit patterns (P < 0.001). The dynamic ApEn curve from the sliding window analysis is capable of tracking variations in EMG activity, thus providing a vivid, distinctive description for different patterns of spontaneous motor unit action potentials in terms of their complexity. These findings expand the existing knowledge of spontaneous motor unit activity in ALS beyond what was previously obtained using conventional linear methods such as firing rate or inter-spike interval statistics.

Respiratory chain deficiency in aged spinal motor neurons☆

PubMed Central

Rygiel, Karolina A.; Grady, John P.; Turnbull, Doug M.

2014-01-01

Sarcopenia, muscle wasting, and strength decline with age, is an important cause of loss of mobility in the elderly individuals. The underlying mechanisms are uncertain but likely to involve defects of motor nerve, neuromuscular junction, and muscle. Loss of motor neurons with age and subsequent denervation of skeletal muscle has been recognized as one of the contributing factors. This study investigated aspects of mitochondrial biology in spinal motor neurons from elderly subjects. We found that protein components of complex I of mitochondrial respiratory chain were reduced or absent in a proportion of aged motor neurons–a phenomenon not observed in fetal tissue. Further investigation showed that complex I-deficient cells had reduced mitochondrial DNA content and smaller soma size. We propose that mitochondrial dysfunction in these motor neurons could lead to the cell loss and ultimately denervation of muscle fibers. PMID:24684792

Amblyopia and binocular vision.

PubMed

Birch, Eileen E

2013-03-01

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3%-3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia. Copyright © 2012 Elsevier Ltd. All rights reserved.

Reciprocal inhibition between motor neurons of the tibialis anterior and triceps surae in humans.

PubMed

Yavuz, Utku Ş; Negro, Francesco; Diedrichs, Robin; Farina, Dario

2018-05-01

Motor neurons innervating antagonist muscles receive reciprocal inhibitory afferent inputs to facilitate the joint movement in the two directions. The present study investigates the mutual transmission of reciprocal inhibitory afferent inputs between the tibialis anterior (TA) and triceps surae (soleus and medial gastrocnemius) motor units. We assessed this mutual mechanism in large populations of motor units for building a statistical distribution of the inhibition amplitudes during standardized input to the motor neuron pools to minimize the effect of modulatory pathways. Single motor unit activities were identified using high-density surface electromyography (HDsEMG) recorded from the TA, soleus (Sol), and medial gastrocnemius (GM) muscles during isometric dorsi- and plantarflexion. Reciprocal inhibition on the antagonist muscle was elicited by electrical stimulation of the tibial (TN) or common peroneal nerves (CPN). The probability density distributions of reflex strength for each muscle were estimated to examine the strength of mutual transmission of reciprocal inhibitory input. The results showed that the strength of reciprocal inhibition in the TA motor units was fourfold greater than for the GM and the Sol motor units. This suggests an asymmetric transmission of reciprocal inhibition between ankle extensor and flexor muscles. This asymmetry cannot be explained by differences in motor unit type composition between the investigated muscles since we sampled low-threshold motor units in all cases. Therefore, the differences observed for the strength of inhibition are presumably due to a differential reciprocal spindle afferent input and the relative contribution of nonreciprocal inhibitory pathways. NEW & NOTEWORTHY We investigated the mutual transmission of reciprocal inhibition in large samples of motor units using a standardized input (electrical stimulation) to the motor neurons. The results demonstrated that the disynaptic reciprocal inhibition exerted between ankle flexor and extensor muscles is asymmetric. The functional implication of asymmetric transmission may be associated with the neural strategies of postural control.

Kinematic analysis of handwriting movements in patients with obsessive-compulsive disorder

PubMed Central

Mavrogiorgou, P; Mergl, R; Tigges, P; El Husseini, J; Schroter, A; Juckel, G; Zaudig, M; Hegerl, U

2001-01-01

OBJECTIVES—Basal ganglia dysfunction is supposed to play a part in the pathophysiology of obsessive-compulsive disorder (OCD). A new computer aided technique for the analysis of hand movements, allowing the detection of subtle motor performance abnormalities, was applied in this study of patients with OCD and healthy controls.
METHODS—Using a digitising graphic tablet, hand motor performance was studied in 22 unmedicated patients with OCD and compared with 22 healthy controls. All subjects drew superimposed concentric circles with both the right and the left hand, in addition to writing a given sentence, their personal signature, and letter sequences in four different sizes. Kinematic parameters were calculated to quantify hand motion.
RESULTS—Patients with OCD had significant impairments of handwriting performance, reflected by lower peak velocity (sentence t=3.6; p=0.001; signature t=2.8; p=0.01) and micrographia (sentence t=3.4; p=0.002; signature t=2.5; p=0.02), compared with controls and shortened acceleration phases per stroke (sentence t=2.4; p=0.02; signature t=4.1; p=0.000). By contrast, in repetitive drawing, patients with OCD had higher peak velocity than healthy controls (group×task interaction p<0.01). There were no significant differences in left and right hand performance between groups. Patients with early versus late age of onset differed in handwriting parameters, such as handwriting consistency. Greater severity of obsessions and compulsions correlated with increasingly poor handwriting performance in patients with OCD.
CONCLUSIONS—A subtle motor dysfunction in OCD can be detected with a digitising tablet. The findings show handwriting impairments in patients with OCD, in line with the assumption that basal ganglia dysfunction is part of OCD pathophysiology. Repetitive motor pattern performance was not impaired, but rather tended to be even better in patients with OCD than in controls. The findings also support the concept that patients with OCD with early versus late age of onset differ in pathophysiological mechanisms and basal ganglia dysfunction.

 PMID:11309453

Motor function outcomes of pediatric patients with hemiplegic cerebral palsy after rehabilitation treatment: a diffusion tensor imaging study

PubMed Central

Kim, Jin Hyun; Kwon, Yong Min; Son, Su Min

2015-01-01

Previous diffusion tensor imaging (DTI) studies regarding pediatric patients with motor dysfunction have confirmed the correlation between DTI parameters of the injured corticospinal tract and the severity of motor dysfunction. There is also evidence that DTI parameters can help predict the prognosis of motor function of patients with cerebral palsy. But few studies are reported on the DTI parameters that can reflect the motor function outcomes of pediatric patients with hemiplegic cerebral palsy after rehabilitation treatment. In the present study, 36 pediatric patients with hemiplegic cerebral palsy were included. Before and after rehabilitation treatment, DTI was used to measure the fiber number (FN), fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of bilateral corticospinal tracts. Functional Level of Hemiplegia scale (FxL) was used to assess the therapeutic effect of rehabilitative therapy on clinical hemiplegia. Correlation analysis was performed to assess the statistical interrelationship between the change amount of DTI parameters and FxL. DTI findings obtained at the initial and follow-up evaluations demonstrated that more affected corticospinal tract yielded significantly decreased FN and FA values and significantly increased ADC value compared to the less affected corticospinal tract. Correlation analysis results showed that the change amount of FxL was positively correlated to FN and FA values, and the correlation to FN was stronger than the correlation to FA. The results suggest that FN and FA values can be used to evaluate the motor function outcomes of pediatric patients with hemiplegic cerebral palsy after rehabilitation treatment and FN is of more significance for evaluation. PMID:26170825

Japan Report.

DTIC Science & Technology

1985-05-24

United States, MITI has restrained growth rates of three big makers— Toyota Motor Corp, Nissan Motor Co and Honda Motor Co—in the fiscal year that started...617,000 units and 544,000 units, respectively, the sources said. Toyota shipped 551,790 units and Nissan 487,040 units in fiscal 1984. Honda is...35,010 units and Isuzu 29,500 units by their own outlets. 60 Toyota and Nissan are each being allotted an identical raise of" 11.9 percent, to some

Remodeling of motor units after nerve regeneration studied by quantitative electromyography.

PubMed

Krarup, Christian; Boeckstyns, Michel; Ibsen, Allan; Moldovan, Mihai; Archibald, Simon

2016-02-01

Peripheral nerve has the capacity to regenerate after nerve lesions; during reinnervation of muscle motor units are gradually reestablished. The aim of this study was to follow the time course of reestablishing and remodeling of motor units in relation to recovery of force after different types of nerve repair. Reinnervation of muscle was compared clinically and electrophysiologically in complete median or ulnar nerve lesions with short gap lengths in the distal forearm repaired with a collagen nerve conduit (11 nerves) or nerve suture (10 nerves). Reestablishment of motor units was studied by quantitative EMG and recording of evoked compound muscle action potential (CMAP) during a 24-month observation period after nerve repair. Force recovered partially to about 80% of normal. Denervation activity gradually decreased during reinnervation though it was still increased at 24 months. Nascent motor unit potentials (MUPs) at early reinnervation were prolonged and polyphasic. During longitudinal studies, MUPs remained prolonged and their amplitudes gradually increased markedly. Firing of MUPs was unstable throughout the study. CMAPs gradually increased and the number of motor units recovered to approximately 20% of normal. There was weak evidence of CMAP amplitude recovery after suture ahead of conduit repair but without treatment related differences at 2 years. Surgical repair of nerve lesions with a nerve conduit or suture supported recovery of force and of motor unit reinnervation to the same extent. Changes occurred at a higher rate during early regeneration and slower after 12 months but should be followed for at least 2 years to assess outcome. EMG changes reflected extensive remodeling of motor units from early nascent units to a mature state with greatly enlarged units due to axonal regeneration and collateral sprouting and maturation of regenerated nerve and reinnervated muscle fibers after both types of repair. Remodeling of motor units after peripheral nerve lesions provides the basis for better recovery of force than the number of motor axons and units. There were no differences after repair with a collagen nerve conduit and nerve suture at short nerve gap lengths. The reduced number of motor units indicates that further improvement of repair procedures and nerve environment is needed. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Motor unit number estimates and neuromuscular transmission in the tibialis anterior of master athletes: evidence that athletic older people are not spared from age-related motor unit remodeling.

PubMed

Piasecki, Mathew; Ireland, Alex; Coulson, Jessica; Stashuk, Dan W; Hamilton-Wright, Andrew; Swiecicka, Agnieszka; Rutter, Martin K; McPhee, Jamie S; Jones, David A

2016-10-01

Muscle motor unit numbers decrease markedly in old age, while remaining motor units are enlarged and can have reduced neuromuscular junction transmission stability. However, it is possible that regular intense physical activity throughout life can attenuate this remodeling. The aim of this study was to compare the number, size, and neuromuscular junction transmission stability of tibialis anterior (TA) motor units in healthy young and older men with those of exceptionally active master runners. The distribution of motor unit potential (MUP) size was determined from intramuscular electromyographic signals recorded in healthy male Young (mean ± SD, 26 ± 5 years), Old (71 ± 4 years) and Master Athletes (69 ± 3 years). Relative differences between groups in numbers of motor units was assessed using two methods, one comparing MUP size and muscle cross-sectional area (CSA) determined with MRI, the other comparing surface recorded MUPs with maximal compound muscle action potentials and commonly known as a "motor unit number estimate (MUNE)". Near fiber (NF) jiggle was measured to assess neuromuscular junction transmission stability. TA CSA did not differ between groups. MUNE values for the Old and Master Athletes were 45% and 40%, respectively, of the Young. Intramuscular MUPs of Old and Master Athletes were 43% and 56% larger than Young. NF jiggle was slightly higher in the Master Athletes, with no difference between Young and Old. These results show substantial and similar motor unit loss and remodeling in Master Athletes and Old individuals compared with Young, which suggests that lifelong training does not attenuate the age-related loss of motor units. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

The effects of local forearm muscle cooling on motor unit properties.

PubMed

Mallette, Matthew M; Green, Lara A; Gabriel, David A; Cheung, Stephen S

2018-02-01

Muscle cooling impairs maximal force. Using needle electromyography (EMG) to assess motor unit properties during muscle cooling, is limited and equivocal. Therefore, we aimed to determine the impact of local muscle cooling on motor unit firing properties using surface EMG decomposition. Twenty participants (12 M, 8 F) completed maximal, evoked, and trapezoidal contractions during thermoneutral and cold muscle conditions. Forearm muscle temperature was manipulated using 10-min neutral (~ 32 °C) or 20-min cold (~ 3 °C) water baths. Twitches and maximal voluntary contractions were performed prior to, and after, forearm immersion in neutral or cold water. Motor unit properties were assessed during trapezoidal contractions to 50% baseline force using surface EMG decomposition. Impaired contractile properties from muscle cooling were evident in the twitch amplitude, duration, and rate of force development indicating that the muscle was successfully cooled from the cold water bath (all d ≥ 0.5, P < 0.05). Surface EMG decomposition showed muscle cooling increased the number of motor units (d = 0.7, P = 0.01) and motor unit action potential (MUAP) duration (d = 0.6, P < 0.001), but decreased MUAP amplitude (d = 0.2, P = 0.012). Individually, neither motor unit firing rates (d = 0.1, P = 0.843) nor recruitment threshold (d = 0.1, P = 0.746) changed; however, the relationship between the recruitment threshold and motor unit firing rate was steeper (d = 1.0, P < 0.001) and had an increased y-intercept (d = 0.9, P = 0.007) with muscle cooling. Since muscle contractility is impaired with muscle cooling, these findings suggest a compensatory increase in the number of active motor units, and small but coupled changes in motor unit firing rates and recruitment threshold to produce the same force.

An Indexed Bibliography on Tracking

DTIC Science & Technology

1990-07-01

Fitts, P. M., & Schneider, R. H. (1955). Reproduction of simple movements as a function of factors influencing proprioceptive feedback. Journal Qf...V dysfunction, dysmetric, dyslexia, and dyspraxia. Academic Therapy, 12(1), 5-27. 0314 Franks, I.M. & Wilberg, R.B. (1984). Consistent reproduction ...sensori-motor skills. ErggnQ jQ, 1.(4), 407-415. 0851 Pearson, P. (1982). Effects of post- hypnotic suggestion on the performance of a fine motor skill

Relationships of Behavioral Measures of Frontal Lobe Dysfunction with Underlying Electrophysiology in Cocaine-Dependent Patients

PubMed Central

Gjini, Klevest; Qazi, Aisha; Greenwald, Mark K.; Sandhu, Ravinder; Gooding, Diane C.; Boutros, Nash N.

2013-01-01

Background and Objectives Despite evidence that frontal lobe functioning is impaired in cocaine-dependent individuals, relationships between behavioral measures of frontal dysfunction and electrophysiological measures of inhibition in cocaine use have not been explored. Methods Using the Frontal System Behavior Scale (FrSBe), frontal dysfunction was assessed in a group of abstinent cocaine-dependent subjects (N=49) and healthy controls (N=32). Using transcranial magnetic stimulation (TMS) and evoked potential (EP)-based electrophysiological measures of inhibition, we assessed associations between these measures and FrSBe estimates of frontal dysfunction. Results Patients had significantly higher FrSBe scores for executive dysfunction, disinhibition and apathy than controls. Lower TMS-based resting motor thresholds (i.e., hyperexcitability) were significantly associated with higher Executive Dysfunction scores in the patients. Conclusions and Scientific Significance Relationships between FrSBe scores and TMS-based measures highlight neurophysiological aberrations underlying frontal lobe dysfunction in cocaine abusers. TMS and EP measures may be useful probes of the intermediary steps between frontal lobe dysfunction and addictive behavior. PMID:24724884

[The Influence of the Functioning of Brain Regulatory Systems onto the Voluntary Regulation of Cognitive Performance in Children. Report 2. Neuropsychological and Electrophysiological Assessment of Brain Regulatory Functions in Children Aged 10-12 with Learning Difficulties].

PubMed

Semenova, O A; Machinskaya, R I

2015-01-01

A total number of 172 children aged 10-12 were electrophysiologically and neuropsychologically assessed in order to analyze the influence of the functioning of brain regulatory systems onto the voluntary regulation of cognitive performance during the preteen years. EEG patterns associated with the nonoptimal functioning of brain regulatory systems, particularly fronto-thalamic, limbic and fronto-striatal structures were significantly more often observed in children with learning and behavioral difficulties, as compared to the control group. Neuropsychological assessment showed that the nonoptimal functioning of different brain regulatory systems specifically affect the voluntary regulation of cognitive performance. Children with EEG patterns of fronto-thalamic nonoptimal functioning demonstrated poor voluntary regulation such as impulsiveness and difficulties in continuing the same algorithms. Children with EEG patterns of limbic nonoptimal functioning showed a less pronounced executive dysfunction manifested only in poor switching between program units within a task. Children with EEG patterns of fronto-striatal nonoptimal functioning struggled with such executive dysfunctions as motor and tactile perseverations and emotional-motivational deviations such as poor motivation and communicative skills.

Corticobasal degeneration.

PubMed

Stover, N P; Watts, R L

2001-01-01

Corticobasal degeneration (CBG) is an increasingly recognized neurodegenerative disease with both motor and cognitive dysfunction. The diagnosis is probably underestimated because of the heterogeneity of clinical features, overlap with symptoms, and pathologic findings of other neurodegenerative diseases. The most characteristic initial motor symptoms are akinesia, rigidity, and apraxia. Dystonia and alien limb phenomena are frequently observed. There is often a parkinsonian picture with failure or lack of efficacy of dopaminergic medical therapy. Cognitive decline, prompting the diagnosis of dementia, may be the most common presentation of CBD that is misdiagnosed. Pathology is characterized by an asymmetric frontoparietal neuronal loss and gliosis with ballooned, achromatic cortical neurons, nigral degeneration, and variable subcortical involvement. Neuroimaging and electrophysiologic studies may help with the diagnosis but are not specific. Treatment is primarily symptomatic and minimally effective, especially after the first several years of symptoms. CBD should be considered in the differential diagnosis of patients with motor and cognitive dysfunction presenting with cortical and subcortical features. Further studies to elucidate molecular abnormalities and biological markers associated with CBD are needed to improve clinical diagnosis and treatment of patients with this disorder.

Evidence-based therapies for upper extremity dysfunction.

PubMed

Liepert, Joachim

2010-12-01

The diversity of interventions aimed at improving upper extremity dysfunction is increasing. This article reviews the effectiveness of different therapeutic approaches that have been published in 2009 and 2010. Evidence is based on randomized controlled trials, systematic reviews, and meta-analyses. Application of constraint-induced movement therapy in acute stroke patients was not more effective than a control intervention, and a more intense therapy may even be harmful. Botulinum toxin injections do not only reduce spasticity but, in children, also improve motor functions if combined with occupational therapy. Strength training improves arm function but not necessarily activities of daily living. Bilateral arm training is as effective as other interventions. Extrinsic feedback and sensory training may further improve motor functions. Mirror therapy was particularly effective for patients with initial hand plegia. For some interventions (e.g. constraint-induced movement therapy, botulinum toxin), efficacy is evident, for others (e.g. mental practice, virtual reality), well designed studies with sufficient numbers of patients are needed. The ultimate goal still is to develop evidence-based therapies for all different degrees of motor impairment.

Motor unit recruitment in human genioglossus muscle in response to hypercapnia.

PubMed

Nicholas, Christian L; Bei, Bei; Worsnop, Christopher; Malhotra, Atul; Jordan, Amy S; Saboisky, Julian P; Chan, Julia K M; Duckworth, Ella; White, David P; Trinder, John

2010-11-01

single motor unit recordings of the genioglossus (GG) muscle indicate that GG motor units have a variety of discharge patterns, including units that have higher discharge rates during inspiration (inspiratory phasic and inspiratory tonic), or expiration (expiratory phasic and expiratory tonic), or do not modify their rate with respiration (tonic). Previous studies have shown that an increase in GG muscle activity is a consequence of increased activity in inspiratory units. However, there are differences between studies as to whether this increase is primarily due to recruitment of new motor units (motor unit recruitment) or to increased discharge rate of already active units (rate coding). Sleep-wake state studies in humans have suggested the former, while hypercapnia experiments in rats have suggested the latter. In this study, we investigated the effect of hypercapnia on GG motor unit activity in humans during wakefulness. sleep research laboratory. sixteen healthy men. each participant was administered at least 6 trials with P(et)CO(2) being elevated 8.4 (SD = 1.96) mm Hg over 2 min following a 30-s baseline. Subjects were instrumented for GG EMG and respiratory measurements with 4 fine wire electrodes inserted subcutaneously into the muscle. One hundred forty-one motor units were identified during the baseline: 47% were inspiratory modulated, 29% expiratory modulated, and 24% showed no respiratory related modulation. Sixty-two new units were recruited during hypercapnia. The distribution of recruited units was significantly different from the baseline distribution, with 84% being inspiratory modulated (P < 0.001). Neither units active during baseline, nor new units recruited during hypercapnia, increased their discharge rate as P(et)CO(2) increased (P > 0.05 for all comparisons). increased GG muscle activity in humans occurs because of recruitment of previously inactive inspiratory modulated units.

Human motor unit recordings: origins and insight into the integrated motor system.

PubMed

Duchateau, Jacques; Enoka, Roger M

2011-08-29

Soon after Edward Liddell [1895-1981] and Charles Sherrington [1857-1952] introduced the concept of a motor unit in 1925 and the necessary technology was developed, the recording of single motor unit activity became feasible in humans. It was quickly discovered by Edgar Adrian [1889-1977] and Detlev Bronk [1897-1975] that the force exerted by muscle during voluntary contractions was the result of the concurrent recruitment of motor units and modulation of the rate at which they discharged action potentials. Subsequent studies found that the relation between discharge frequency and motor unit force was characterized by a sigmoidal function. Based on observations on experimental animals, Elwood Henneman [1915-1996] proposed a "size principle" in 1957 and most studies in humans focussed on validating this concept during various types of muscle contractions. By the end of the 20th C, the experimental evidence indicated that the recruitment order of human motor units was determined primarily by motoneuron size and that the occasional changes in recruitment order were not an intended strategy of the central nervous system. Fundamental knowledge on the function of Sherrington's "common final pathway" was expanded with observations on motor unit rotation, minimal and maximal discharge rates, discharge variability, and self-sustained firing. Despite the great amount of work on characterizing motor unit activity during the first century of inquiry, however, many basic questions remain unanswered and these limit the extent to which findings on humans and experimental animals can be integrated and generalized to all movements. 2011 Elsevier B.V. All rights reserved.

Examination of Poststroke Alteration in Motor Unit Firing Behavior Using High-Density Surface EMG Decomposition.

PubMed

Li, Xiaoyan; Holobar, Ales; Gazzoni, Marco; Merletti, Roberto; Rymer, William Zev; Zhou, Ping

2015-05-01

Recent advances in high-density surface electromyogram (EMG) decomposition have made it a feasible task to discriminate single motor unit activity from surface EMG interference patterns, thus providing a noninvasive approach for examination of motor unit control properties. In the current study, we applied high-density surface EMG recording and decomposition techniques to assess motor unit firing behavior alterations poststroke. Surface EMG signals were collected using a 64-channel 2-D electrode array from the paretic and contralateral first dorsal interosseous (FDI) muscles of nine hemiparetic stroke subjects at different isometric discrete contraction levels between 2 to 10 N with a 2 N increment step. Motor unit firing rates were extracted through decomposition of the high-density surface EMG signals and compared between paretic and contralateral muscles. Across the nine tested subjects, paretic FDI muscles showed decreased motor unit firing rates compared with contralateral muscles at different contraction levels. Regression analysis indicated a linear relation between the mean motor unit firing rate and the muscle contraction level for both paretic and contralateral muscles (p < 0.001), with the former demonstrating a lower increment rate (0.32 pulses per second (pps)/N) compared with the latter (0.67 pps/N). The coefficient of variation (averaged over the contraction levels) of the motor unit firing rates for the paretic muscles (0.21 ± 0.012) was significantly higher than for the contralateral muscles (0.17 ± 0.014) (p < 0.05). This study provides direct evidence of motor unit firing behavior alterations poststroke using surface EMG, which can be an important factor contributing to hemiparetic muscle weakness.

Motor unit recruitment strategies and muscle properties determine the influence of synaptic noise on force steadiness

PubMed Central

Dideriksen, Jakob L.; Negro, Francesco; Enoka, Roger M.

2012-01-01

Motoneurons receive synaptic inputs from tens of thousands of connections that cause membrane potential to fluctuate continuously (synaptic noise), which introduces variability in discharge times of action potentials. We hypothesized that the influence of synaptic noise on force steadiness during voluntary contractions is limited to low muscle forces. The hypothesis was examined with an analytical description of transduction of motor unit spike trains into muscle force, a computational model of motor unit recruitment and rate coding, and experimental analysis of interspike interval variability during steady contractions with the abductor digiti minimi muscle. Simulations varied contraction force, level of synaptic noise, size of motor unit population, recruitment range, twitch contraction times, and level of motor unit short-term synchronization. Consistent with the analytical derivations, simulations and experimental data showed that force variability at target forces above a threshold was primarily due to low-frequency oscillations in neural drive, whereas the influence of synaptic noise was almost completely attenuated by two low-pass filters, one related to convolution of motoneuron spike trains with motor unit twitches (temporal summation) and the other attributable to summation of single motor unit forces (spatial summation). The threshold force above which synaptic noise ceased to influence force steadiness depended on recruitment range, size of motor unit population, and muscle contractile properties. This threshold was low (<10% of maximal force) for typical values of these parameters. Results indicate that motor unit recruitment and muscle properties of a typical muscle are tuned to limit the influence of synaptic noise on force steadiness to low forces and that the inability to produce a constant force during stronger contractions is mainly attributable to the common low-frequency oscillations in motoneuron discharge rates. PMID:22423000

Examination of Post-stroke Alteration in Motor Unit Firing Behavior Using High Density Surface EMG Decomposition

PubMed Central

Li, Xiaoyan; Holobar, Aleš; Gazzoni, Marco; Merletti, Roberto; Rymer, William Z.; Zhou, Ping

2014-01-01

Recent advances in high density surface electromyogram (EMG) decomposition have made it a feasible task to discriminate single motor unit activity from surface EMG interference patterns, thus providing a noninvasive approach for examination of motor unit control properties. In the current study we applied high density surface EMG recording and decomposition techniques to assess motor unit firing behavior alterations post-stroke. Surface EMG signals were collected using a 64-channel 2-dimensional electrode array from the paretic and contralateral first dorsal interosseous (FDI) muscles of nine hemiparetic stroke subjects at different isometric discrete contraction levels between 2 N to 10 N with a 2 N increment step. Motor unit firing rates were extracted through decomposition of the high density surface EMG signals, and compared between paretic and contralateral muscles. Across the nine tested subjects, paretic FDI muscles showed decreased motor unit firing rates compared with contralateral muscles at different contraction levels. Regression analysis indicated a linear relation between the mean motor unit firing rate and the muscle contraction level for both paretic and contralateral muscles (p < 0.001), with the former demonstrating a lower increment rate (0.32 pulses per second (pps)/N) compared with the latter (0.67 pps/N). The coefficient of variation (CoV, averaged over the contraction levels) of the motor unit firing rates for the paretic muscles (0.21 ± 0.012) was significantly higher than for the contralateral muscles (0.17 ± 0.014) (p < 0.05). This study provides direct evidence of motor unit firing behavior alterations post-stroke using surface EMG, which can be an important factor contributing to hemiparetic muscle weakness. PMID:25389239

Recruitment of motor units in two fascicles of the semispinalis cervicis muscle

PubMed Central

Schomacher, Jochen; Dideriksen, Jakob Lund; Farina, Dario

2012-01-01

This study investigated the behavior of motor units in the semispinalis cervicis muscle. Intramuscular EMG recordings were obtained unilaterally at levels C2 and C5 in 15 healthy volunteers (8 men, 7 women) who performed isometric neck extensions at 5%, 10%, and 20% of the maximal force [maximum voluntary contraction (MVC)] for 2 min each and linearly increasing force contractions from 0 to 30% MVC over 3 s. Individual motor unit action potentials were identified. The discharge rate and interspike interval variability of the motor units in the two locations did not differ. However, the recruitment threshold of motor units detected at C2 (n = 16, mean ± SD: 10.3 ± 6.0% MVC) was greater than that of motor units detected at C5 (n = 92, 6.9 ± 4.3% MVC) (P < 0.01). A significant level of short-term synchronization was identified in 246 of 307 motor unit pairs when computed within one spinal level but only in 28 of 110 pairs of motor units between the two levels. The common input strength, which quantifies motor unit synchronization, was greater for pairs within one level (0.47 ± 0.32) compared with pairs between levels (0.09 ± 0.07) (P < 0.05). In a second experiment on eight healthy subjects, interference EMG was recorded from the same locations during a linearly increasing force contraction from 0 to 40% MVC and showed significantly greater EMG amplitude at C5 than at C2. In conclusion, synaptic input is distributed partly independently and nonuniformly to different fascicles of the semispinalis cervicis muscle. PMID:22402657

Basic and advanced echocardiographic evaluation of myocardial dysfunction in sepsis and septic shock.

PubMed

Vallabhajosyula, S; Pruthi, S; Shah, S; Wiley, B M; Mankad, S V; Jentzer, J C

2018-01-01

Sepsis continues to be a leading cause of mortality and morbidity in the intensive care unit. Cardiovascular dysfunction in sepsis is associated with worse short- and long-term outcomes. Sepsis-related myocardial dysfunction is noted in 20%-65% of these patients and manifests as isolated or combined left or right ventricular systolic or diastolic dysfunction. Echocardiography is the most commonly used modality for the diagnosis of sepsis-related myocardial dysfunction. With the increasing use of ultrasonography in the intensive care unit, there is a renewed interest in sepsis-related myocardial dysfunction. This review summarises the current scope of literature focused on sepsis-related myocardial dysfunction and highlights the use of basic and advanced echocardiographic techniques for the diagnosis of sepsis-related myocardial dysfunction and the management of sepsis and septic shock.

Psychometrics of the neonatal oral motor assessment scale.

PubMed

Zarem, Cori; Kidokoro, Hiroyuki; Neil, Jeffrey; Wallendorf, Michael; Inder, Terrie; Pineda, Roberta

2013-12-01

To establish the psychometrics of the Neonatal Oral Motor Assessment Scale (NOMAS). In this prospective cohort study of 75 preterm infants (39 females, 36 males) born at or before 30 weeks gestation (mean gestational age 26.56 wks, SD 1.90, range 23-30 wks; mean birthweight 967.33 g, SD 288.54, range 480-2240), oral feeding was videotaped before discharge from the neonatal intensive care unit (NICU). The NOMAS was used to classify feeding as normal, disorganized, or dysfunctional. Neurobehavior was assessed at term equivalent, and infants underwent magnetic resonance imaging. Children returned for developmental testing at 2 years corrected age. Associations between NOMAS scores and (1) neurobehavior; (2) cerebral injury and metrics; and (3) developmental outcome were investigated using χ(2) -analyses, t-tests, and linear regression. For reliability, six certified NOMAS evaluators rated five randomly selected NOMAS recordings and re-scored them 2 weeks later in a second randomized order. Reliability was calculated with Cohen's kappa statistics. Dysfunctional NOMAS scores were associated with lower Dubowitz scores [t=-2.14; mean difference -2.32 (95% confidence interval [CI] -0.157 to -4.49); p=0.036], higher stress on the NICU Network Neurobehavioral Scale (t=2.61; mean difference 0.073 [95% CI 0.017-0.129]; p=0.0110), and decreased transcerebellar diameter (t=-2.22; mean difference -2.04 [CI=-3.89 to -0.203]; p=0.03). No significant associations were found between NOMAS scores and 2-year outcome. Some concurrent validity was established with associations between NOMAS scores and measures of infant behavior and cerebral structure. The NOMAS did not show predictive validity in this study of preterm infants at high risk of developmental delay. Reliability was variable and suboptimal. © 2013 Mac Keith Press.

Psychometrics of the neonatal oral motor assessment scale

PubMed Central

Zarem, Cori S; Kidokoro, Hiroyuki; Neil, Jeffrey; Wallendorf, Michael; Inder, Terrie; Pineda, Roberta

2013-01-01

AIM To establish the psychometrics of the Neonatal Oral Motor Assessment Scale (NOMAS). METHOD In this prospective cohort study of 75 preterm infants (39 females,36 males) born at 30 weeks' or less gestation (mean gestational age 26.56wk, SD 1.90, range 23–30wk; mean birthweight 967.33g, SD 288.54, range 480–2240), oral feeding was videotaped before discharge from the neonatal intensive care unit (NICU) discharge. The NOMAS was used to classify feeding as normal, disorganized, or dysfunctional. Neurobehavior was assessed at term equivalent, and infants underwent magnetic resonance imaging. Children returned for developmental testing at 2 years corrected age. Associations between NOMAS scores and (1) neurobehavior, (2) cerebral injury and metrics, and (3) developmental outcome were investigated using χ2-analyses, t-tests, and linear regression. For reliability, six certified NOMAS evaluators rated five randomly selected NOMAS recordings and re-scored them in a second randomized order. Reliability was calculated with Cohen’s kappa coefficient. RESULTS Dysfunctional NOMAS scores were associated with lower Dubowitz scores [t=–2.14; mean difference –2.32 (95% confidence interval [CI] –0.157 to –4.49); p=0.036], higher stress on the NICU Network Neurobehavioral Scale (t=2.61; mean difference 0.073 [95% CI 0.017 to 0.129]; p=0.0110, and decreased transcerebellar diameter (t=–2.22; mean difference –2.04 [CI=–3.89 to –0.203]; p=0.03). No significant associations were found between NOMAS scores and 2 year outcome. INTERPRETATION Some concurrent validity was established with associations between NOMAS scores and measures of infant behavior and cerebral structure. The NOMAS did not show predictive validity in this study of preterm infants at high risk of developmental delay. Reliability was variable and suboptimal. PMID:23869958

Language learning impairments: integrating basic science, technology, and remediation.

PubMed

Tallal, P; Merzenich, M M; Miller, S; Jenkins, W

1998-11-01

One of the fundamental goals of the modern field of neuroscience is to understand how neuronal activity gives rise to higher cortical function. However, to bridge the gap between neurobiology and behavior, we must understand higher cortical functions at the behavioral level at least as well as we have come to understand neurobiological processes at the cellular and molecular levels. This is certainly the case in the study of speech processing, where critical studies of behavioral dysfunction have provided key insights into the basic neurobiological mechanisms relevant to speech perception and production. Much of this progress derives from a detailed analysis of the sensory, perceptual, cognitive, and motor abilities of children who fail to acquire speech, language, and reading skills normally within the context of otherwise normal development. Current research now shows that a dysfunction in normal phonological processing, which is critical to the development of oral and written language, may derive, at least in part, from difficulties in perceiving and producing basic sensory-motor information in rapid succession--within tens of ms (see Tallal et al. 1993a for a review). There is now substantial evidence supporting the hypothesis that basic temporal integration processes play a fundamental role in establishing neural representations for the units of speech (phonemes), which must be segmented from the (continuous) speech stream and combined to form words, in order for the normal development of oral and written language to proceed. Results from magnetic resonance imaging (MRI) and positron emission tomography (PET) studies, as well as studies of behavioral performance in normal and language impaired children and adults, will be reviewed to support the view that the integration of rapidly changing successive acoustic events plays a primary role in phonological development and disorders. Finally, remediation studies based on this research, coupled with neuroplasticity research, will be presented.

Changes in muscle fiber conduction velocity indicate recruitment of distinct motor unit populations.

PubMed

Houtman, C J; Stegeman, D F; Van Dijk, J P; Zwarts, M J

2003-09-01

To obtain more insight into the changes in mean muscle fiber conduction velocity (MFCV) during sustained isometric exercise at relatively low contraction levels, we performed an in-depth study of the human tibialis anterior muscle by using multichannel surface electromyogram. The results show an increase in MFCV after an initial decrease of MFCV at 30 or 40% maximum voluntary contraction in all of the five subjects studied. With a peak velocity analysis, we calculated the distribution of conduction velocities of action potentials in the bipolar electromyogram signal. It shows two populations of peak velocities occurring simultaneously halfway through the exercise. The MFCV pattern implies the recruitment of two different populations of motor units. Because of the lowering of MFCV of the first activated population of motor units, the newly recruited second population of motor units becomes visible. It is most likely that the MFCV pattern can be ascribed to the fatiguing of already recruited predominantly type I motor units, followed by the recruitment of fresh, predominantly type II, motor units.

In Vivo Imaging of Human Sarcomere Twitch Dynamics in Individual Motor Units.

PubMed

Sanchez, Gabriel N; Sinha, Supriyo; Liske, Holly; Chen, Xuefeng; Nguyen, Viet; Delp, Scott L; Schnitzer, Mark J

2015-12-16

Motor units comprise a pre-synaptic motor neuron and multiple post-synaptic muscle fibers. Many movement disorders disrupt motor unit contractile dynamics and the structure of sarcomeres, skeletal muscle's contractile units. Despite the motor unit's centrality to neuromuscular physiology, no extant technology can image sarcomere twitch dynamics in live humans. We created a wearable microscope equipped with a microendoscope for minimally invasive observation of sarcomere lengths and contractile dynamics in any major skeletal muscle. By electrically stimulating twitches via the microendoscope and visualizing the sarcomere displacements, we monitored single motor unit contractions in soleus and vastus lateralis muscles of healthy individuals. Control experiments verified that these evoked twitches involved neuromuscular transmission and faithfully reported muscle force generation. In post-stroke patients with spasticity of the biceps brachii, we found involuntary microscopic contractions and sarcomere length abnormalities. The wearable microscope facilitates exploration of many basic and disease-related neuromuscular phenomena never visualized before in live humans. Copyright © 2015 Elsevier Inc. All rights reserved.

Discharge patterns of human tensor palatini motor units during sleep onset.

PubMed

Nicholas, Christian L; Jordan, Amy S; Heckel, Leila; Worsnop, Christopher; Bei, Bei; Saboisky, Julian P; Eckert, Danny J; White, David P; Malhotra, Atul; Trinder, John

2012-05-01

Upper airway muscles such as genioglossus (GG) and tensor palatini (TP) reduce activity at sleep onset. In GG reduced muscle activity is primarily due to inspiratory modulated motor units becoming silent, suggesting reduced respiratory pattern generator (RPG) output. However, unlike GG, TP shows minimal respiratory modulation and presumably has few inspiratory modulated motor units and minimal input from the RPG. Thus, we investigated the mechanism by which TP reduces activity at sleep onset. The activity of TP motor units were studied during relaxed wakefulness and over the transition from wakefulness to sleep. Sleep laboratory. Nine young (21.4 ± 3.4 years) males were studied on a total of 11 nights. Sleep onset. Two TP EMGs (thin, hooked wire electrodes), and sleep and respiratory measures were recorded. One hundred twenty-one sleep onsets were identified (13.4 ± 7.2/subject), resulting in 128 motor units (14.3 ± 13.0/subject); 29% of units were tonic, 43% inspiratory modulated (inspiratory phasic 18%, inspiratory tonic 25%), and 28% expiratory modulated (expiratory phasic 21%, expiratory tonic 7%). There was a reduction in both expiratory and inspiratory modulated units, but not tonic units, at sleep onset. Reduced TP activity was almost entirely due to de-recruitment. TP showed a similar distribution of motor units as other airway muscles. However, a greater proportion of expiratory modulated motor units were active in TP and these expiratory units, along with inspiratory units, tended to become silent over sleep onset. The data suggest that both expiratory and inspiratory drive components from the RPG are reduced at sleep onset in TP.

Gastrointestinal disorders in children with neurodevelopmental disabilities.

PubMed

Sullivan, Peter B

2008-01-01

Children with neurodevelopmental disabilities such as cerebral palsy (CP), spina bifida, or inborn errors of metabolism frequently have associated gastrointestinal problems. These include oral motor dysfunction leading to feeding difficulties, risk of aspiration, prolonged feeding times, and malnutrition with its attendant physical compromise. Gastrostomy tube feeding is increasingly being used in these children to circumvent oral motor dysfunction and prevent malnutrition. Foregut dysmotility causes several problems such as dysphagia from oesophageal dysmotility, gastro-oesophageal reflux disease, and delayed gastric emptying. Gastro-oesophageal reflux disease is common in these children but often fails to respond to medical management and may require surgical treatment. Finally, constipation is often a problem that may be overlooked in this population. This article focuses on these associated gastrointestinal manifestations and discusses the current diagnostic and therapeutic options available. (c) 2008 Wiley-Liss, Inc.

Clinical Phenotype of Dementia after Traumatic Brain Injury

PubMed Central

Sayed, Nasreen; Culver, Carlee; Dams-O'Connor, Kristen; Hammond, Flora

2013-01-01

Abstract Traumatic brain injury (TBI) in early to mid-life is associated with an increased risk of dementia in late life. It is unclear whether TBI results in acceleration of Alzheimer's disease (AD)-like pathology or has features of another dementing condition, such as chronic traumatic encephalopathy, which is associated with more-prominent mood, behavior, and motor disturbances than AD. Data from the National Alzheimer's Coordinating Center (NACC) Uniform Data Set was obtained over a 5-year period. Categorical data were analyzed using Fisher's exact test. Continuous parametric data were analyzed using the Student's t-test. Nonparametric data were analyzed using Mann-Whitney's test. Overall, 877 individuals with dementia who had sustained TBI were identified in the NACC database. Only TBI with chronic deficit or dysfunction was associated with increased risk of dementia. Patients with dementia after TBI (n=62) were significantly more likely to experience depression, anxiety, irritability, and motor disorders than patients with probable AD. Autopsy data were available for 20 of the 62 TBI patients. Of the patients with TBI, 62% met National Institute of Aging-Reagan Institute “high likelihood” criteria for AD. We conclude that TBI with chronic deficit or dysfunction is associated with an increased odds ratio for dementia. Clinically, patients with dementia associated with TBI were more likely to have symptoms of depression, agitation, irritability, and motor dysfunction than patients with probable AD. These findings suggest that dementia in individuals with a history of TBI may be distinct from AD. PMID:23374007

Vastus Lateralis Motor Unit Firing Rate Is Higher in Women With Patellofemoral Pain.

PubMed

Gallina, Alessio; Hunt, Michael A; Hodges, Paul W; Garland, S Jayne

2018-05-01

To compare neural drive, determined from motor unit firing rate, in the vastus medialis and lateralis in women with and without patellofemoral pain. Cross-sectional study. University research laboratory. Women (N=56) 19 to 35 years of age, including 36 with patellofemoral pain and 20 controls. Not applicable. Participants sustained an isometric knee extension contraction at 10% of their maximal voluntary effort for 70 seconds. Motor units (N=414) were identified using high-density surface electromyography. Average firing rate was calculated between 5 and 35 seconds after recruitment for each motor unit. Initial firing rate was the inverse of the first 3 motor unit interspike intervals. In control participants, vastus medialis motor units discharged at higher rates than vastus lateralis motor units (P=.001). This was not observed in women with patellofemoral pain (P=.78) because of a higher discharge rate of vastus lateralis compared with control participants (P=.002). No between-group differences were observed for vastus medialis (P=.93). Similar results were obtained for the initial motor unit firing rate. These findings suggest that women with patellofemoral pain have a higher neural drive to vastus lateralis but not vastus medialis, which may be a contributor of the altered patellar kinematics observed in some studies. The different neural drive may be an adaptation to patellofemoral pain, possibly to compensate for decreased quadriceps force production, or a precursor of patellofemoral pain. Copyright © 2018 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Cognitive dysfunction in lower motor neuron disease: executive and memory deficits in progressive muscular atrophy.

PubMed

Raaphorst, Joost; de Visser, Marianne; van Tol, Marie-José; Linssen, Wim H J P; van der Kooi, Anneke J; de Haan, Rob J; van den Berg, Leonard H; Schmand, Ben

2011-02-01

In contrast with findings in amyotrophic lateral sclerosis (ALS), cognitive impairments have as yet not been shown in the lower motor neuron variant of motor neuron disease, progressive spinal muscular atrophy (PMA). The objective of this study was to investigate cognitive function in PMA and to compare the cognitive profile with that of ALS. In addition, visuospatial functions were assessed comprehensively; these tests are underrepresented in earlier neuropsychological investigations in ALS. 23 PMA and 30 ALS patients (vital capacity >70% of predicted value) underwent a neuropsychological assessment adapted to motor impairments: global cognitive and executive functioning, psychomotor speed, memory, language, attention and visuospatial skills. The results were compared with age, education and sex matched controls and with normative data. Compared with controls, PMA patients performed worse on attention/working memory (digit span backward), category fluency and the Mini-Mental State Examination. Compared with normative data, PMA patients most frequently showed impairment on three measures: letter-number sequencing, and immediate and delayed story recall. 17% of PMA patients showed cognitive impairment, defined as performance below 2 SDs from the mean of normative data on at least three neuropsychological tests. In ALS, similar but more extensive cognitive deficits were found. Visuospatial dysfunction was not found in PMA and ALS. 17% of PMA patients have executive and memory impairments. PMA with cognitive impairment adds a formerly unknown phenotype to the existing classification of motor neuron diseases.

A stem-cell based bioassay to critically assess the pathology of dysfunctional neuromuscular junctions.

PubMed

Chipman, Peter H; Zhang, Ying; Rafuse, Victor F

2014-01-01

Pluripotent stem cells can be directed to differentiate into motor neurons and assessed for functionality in vitro. An emerging application of this technique is to model genetically inherited diseases in differentiated motor neurons and to screen for new therapeutic targets. The neuromuscular junction (NMJ) is essential to the functionality of motor neurons and its dysfunction is a primary hallmark of motor neuron disease. However, mature NMJs that possess the functional and morphological characteristics of those formed in vivo have so far not been obtained in vitro. Here we describe the generation and analysis of mature NMJs formed between embryonic stem cell-derived motor neurons (ESCMNs) and primary myotubes. We compared the formation and maturation of NMJs generated by wild-type (NCAM+/+) ESCMNs to those generated by neural cell adhesion molecule null (NCAM-/-) ESCMNs in order to definitively test the sensitivity of this assay to identify synaptic pathology. We find that co-cultures using NCAM-/- ESCMNs replicate key in vivo NCAM-/- phenotypes and reveal that NCAM influences neuromuscular synaptogenesis by controlling the mode of synaptic vesicle endocytosis. Further, we could improve synapse formation and function in NCAM-/- co-cultures by chronic treatment with nifedipine, which blocks an immature synaptic vesicle recycling pathway. Together, our results demonstrate that this ESCMN/myofiber co-culture system is a highly sensitive bioassay for examining molecules postulated to regulate synaptic function and for screening therapeutics that will improve the function of compromised NMJs.

Recruitment order of motor units in human vastus lateralis muscle is maintained during fatiguing contractions.

PubMed

Adam, Alexander; De Luca, Carlo J

2003-11-01

Motor-unit firing patterns were studied in the vastus lateralis muscle of five healthy young men [21.4 +/- 0.9 (SD) yr] during a series of isometric knee extensions performed to exhaustion. Each contraction was held at a constant torque level, set to 20% of the maximal voluntary contraction at the beginning of the experiment. Electromyographic signals, recorded via a quadrifilar fine wire electrode, were processed with the precision decomposition technique to identify the firing times of individual motor units. In repeat experiments, whole-muscle mechanical properties were measured during the fatigue protocol using electrical stimulation. The main findings were a monotonic decrease in the recruitment threshold of all motor units and the progressive recruitment of new units, all without a change of the recruitment order. Motor units from the same subject showed a similar time course of threshold decline, but this decline varied among subjects (mean threshold decrease ranged from 23 to 73%). The mean threshold decline was linearly correlated (R2 >or= 0.96) with a decline in the elicited peak tetanic torque. In summary, the maintenance of recruitment order during fatigue strongly supports the notion that the observed common recruitment adaptations were a direct consequence of an increased excitatory drive to the motor unit pool. It is suggested that the increased central drive was necessary to compensate for the loss in force output from motor units whose muscle fibers were actively contracting. We therefore conclude that the control scheme of motor-unit recruitment remains invariant during fatigue at least in relatively large muscles performing submaximal isometric contractions.

Differential activation of motor units in the wrist extensor muscles during the tonic vibration reflex in man.

PubMed Central

Romaiguère, P; Vedel, J P; Azulay, J P; Pagni, S

1991-01-01

1. Single motor unit activity was recorded in the extensor carpi radialis longus and extensor carpi radialis brevis muscles of five healthy human subjects, using metal microelectrodes. 2. Motor units were characterized on the basis of their twitch contraction times and their force recruitment thresholds during voluntary imposed-ramp contractions. 3. The discharge patterns of forty-three motor units were studied during tonic vibration reflex elicited by prolonged (150 s) trains of vibration (30 Hz) applied to the distal tendons of the muscles. The temporal relationships between the individual small tendon taps of the vibratory stimulus and the motor unit impulses were analysed on dot raster displays and post-stimulus time histograms. 4. After tendon taps, the impulses of motor units with long twitch contraction times (mean +/- S.D., 47.2 +/- 10.7 ms) and low recruitment thresholds (0.88 +/- 0.6 N) formed a single narrow peak (P1) with a latency (22.7 +/- 1.4 ms) which was comparable to that of the tendon jerk in the extensor carpi radialis muscles. These motor units were named 'P1 units'. On the other hand, the response of motor units with shorter twitch contraction times (31.1 +/- 3.3 ms) and higher recruitment thresholds (3.21 +/- 1.3 N) showed two peaks: a short latency (23.4 +/- 1.3 ms) P1 peak similar to the previous one and a P2 peak occurring 9.4 +/- 1.2 ms later. These motor units were named 'P1-P2 units'. 5. When the reflex contraction increased slowly, the P1 peaks of 'P1-P2 units' were clearly predominant at the beginning of the contraction, during the rising phase of the motor unit discharge frequency, while the P2 peaks became predominant when the units had reached their maximal discharge frequency. 6. Increasing the tendon vibration frequency (35, 55, 75, 95 Hz) did not modify the 'P1 unit' discharge pattern. Due to interference between vibration period and peak latencies, increasing the vibration frequency caused the P1 and P2 peaks of 'P1-P2 units' to overlap. 7. Superficial cutaneous stimulation of the dorsal side of the forearm during tendon vibration noticeably decreased the P1 peaks in both types of motor units. In the P2 peaks it could result in either a decrease or an increase but the average effect was a slight increase. 8. When applied 10 s before tendon vibration, cutaneous stimulation considerably suppressed the tonic vibration reflex.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1822565

Surgical and conservative methods for restoring impaired motor function - facial nerve, spinal accessory nerve, hypoglossal nerve (not including vagal nerve or swallowing)

PubMed Central

Laskawi, R.; Rohrbach, S.

2005-01-01

The present review gives a survey of rehabilitative measures for disorders of the motor function of the mimetic muscles (facial nerve), and muscles innervated by the spinal accessory and hypoglossal nerves. The dysfunction can present either as paralysis or hyperkinesis (hyperkinesia). Conservative and surgical treatment options aimed at restoring normal motor function and correcting the movement disorders are described. Static reanimation techniques are not dealt with. The final section describes the use of botulinum toxin in the therapy of dysphagia. PMID:22073058

[Motor system physiotherapy of the masticatory organ].

PubMed

Jagucka-Metel, Wioletta; Brzeska, Paulina; Sobolewska, Ewa; Machoy-Mokrzyńska, Anna; Baranowska, Agata

2013-01-01

The motor system of the masticatory organ is a complex morphological and functional structure. Its dysfunctions are manifested by various symptoms within the masticatory apparatus and in distant organs. The paper presents a discussion on the physiotherapeutic procedure for the treatment of disorders in the motor system of the masticatory organ. Therapeutic methods are presented, including: massage, trigger point therapy, kinesitherapy, biofeedback, manual therapy, postural re-education, kinesiotaping, physical interventions (TENS, hyaluronidase iontophoresis, ultrasound, laser therapy, and magnetoledotherapy). The paper points out the role of a comprehensive approach to the patient in order to eliminate the cause of disorders, going beyond symptomatic treatment.

Attention and driving in traumatic brain injury: a question of coping with time-pressure.

PubMed

Brouwer, Wiebo H; Withaar, Frederiec K; Tant, Mark L M; van Zomeren, Adriaan H

2002-02-01

Diffuse and focal traumatic brain injury (TBI) can result in perceptual, cognitive, and motor dysfunction possibly leading to activity limitations in driving. Characteristic dysfunctions for severe diffuse TBI are confronted with function requirements derived from the hierarchical task analysis of driving skill. Specifically, we focus on slow information processing, divided attention, and the development of procedural knowledge. Also the effects of a combination of diffuse and focal dysfunctions, specifically homonymous hemianopia and the dysexecutive syndrome, are discussed. Finally, we turn to problems and challenges with regard to assessment and rehabilitation methods in the areas of driving and fitness to drive.

Similar alteration of motor unit recruitment strategies during the anticipation and experience of pain.

PubMed

Tucker, Kylie; Larsson, Anna-Karin; Oknelid, Stina; Hodges, Paul

2012-03-01

A motor unit consists of a motoneurone and the multiple muscle fibres that it innervates, and forms the final neural pathway that influences movement. Discharge of motor units is altered (decreased discharge rate and/or cessation of firing; and increased discharge rate and/or recruitment of new units) during matched-force contractions with pain. This is thought to be mediated by nociceptive (pain) input on motoneurones, as demonstrated in animal studies. It is also possible that motoneurone excitability is altered by pain related descending inputs, that these changes persist after noxious stimuli cease, and that direct nociceptive input is not necessary to induce pain related changes in movement. We aimed to determine whether anticipation of pain (descending pain related inputs without nociceptor discharge) alters motor unit discharge, and to observe motor unit discharge recovery after pain has ceased. Motor unit discharge was recorded with fine-wire electrodes in the quadriceps of 9 volunteers. Subjects matched isometric knee-extension force during anticipation of pain (anticipation: electrical shocks randomly applied over the infrapatellar fat-pad); pain (hypertonic saline injected into the fat-pad); and 3 intervening control conditions. Discharge rate of motor units decreased during pain (P<.001) and anticipation (P<.01) compared with control contractions. De-recruitment of 1 population of units and new recruitment of another population were observed during both anticipation and pain; some changes in motor unit recruitment persisted after pain ceased. This challenges the fundamental theory that pain-related changes in muscle activity result from direct nociceptor discharge, and provides a mechanism that may underlie long-term changes in movement/chronicity in some musculoskeletal conditions. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Discharge Patterns of Human Tensor Palatini Motor Units During Sleep Onset

PubMed Central

Nicholas, Christian L.; Jordan, Amy S.; Heckel, Leila; Worsnop, Christopher; Bei, Bei; Saboisky, Julian P.; Eckert, Danny J.; White, David P.; Malhotra, Atul; Trinder, John

2012-01-01

Study Objectives: Upper airway muscles such as genioglossus (GG) and tensor palatini (TP) reduce activity at sleep onset. In GG reduced muscle activity is primarily due to inspiratory modulated motor units becoming silent, suggesting reduced respiratory pattern generator (RPG) output. However, unlike GG, TP shows minimal respiratory modulation and presumably has few inspiratory modulated motor units and minimal input from the RPG. Thus, we investigated the mechanism by which TP reduces activity at sleep onset. Design: The activity of TP motor units were studied during relaxed wakefulness and over the transition from wakefulness to sleep. Setting: Sleep laboratory. Participants: Nine young (21.4 ± 3.4 years) males were studied on a total of 11 nights. Intervention: Sleep onset. Measurements and Results: Two TP EMGs (thin, hooked wire electrodes), and sleep and respiratory measures were recorded. One hundred twenty-one sleep onsets were identified (13.4 ± 7.2/subject), resulting in 128 motor units (14.3 ± 13.0/subject); 29% of units were tonic, 43% inspiratory modulated (inspiratory phasic 18%, inspiratory tonic 25%), and 28% expiratory modulated (expiratory phasic 21%, expiratory tonic 7%). There was a reduction in both expiratory and inspiratory modulated units, but not tonic units, at sleep onset. Reduced TP activity was almost entirely due to de-recruitment. Conclusions: TP showed a similar distribution of motor units as other airway muscles. However, a greater proportion of expiratory modulated motor units were active in TP and these expiratory units, along with inspiratory units, tended to become silent over sleep onset. The data suggest that both expiratory and inspiratory drive components from the RPG are reduced at sleep onset in TP. Citation: Nicholas CL; Jordan AS; Heckel L; Worsnop C; Bei B: Saboisky JP; Eckert DJ; White DP; Malhotra A; Trinder J. Discharge patterns of human tensor palatini motor units during sleep onset. SLEEP 2012;35(5):699-707. PMID:22547896

Motor skill learning and offline-changes in TGA patients with acute hippocampal CA1 lesions.

PubMed

Döhring, Juliane; Stoldt, Anne; Witt, Karsten; Schönfeld, Robby; Deuschl, Günther; Born, Jan; Bartsch, Thorsten

2017-04-01

Learning and the formation of memory are reflected in various memory systems in the human brain such as the hippocampus based declarative memory system and the striatum-cortex based system involved in motor sequence learning. It is a matter of debate how both memory systems interact in humans during learning and consolidation and how this interaction is influenced by sleep. We studied the effect of an acute dysfunction of hippocampal CA1 neurons on the acquisition (on-line condition) and off-line changes of a motor skill in patients with a transient global amnesia (TGA). Sixteen patients (68 ± 4.4 yrs) were studied in the acute phase and during follow-up using a declarative and procedural test, and were compared to controls. Acute TGA patients displayed profound deficits in all declarative memory functions. During the acute amnestic phase, patients were able to acquire the motor skill task reflected by increasing finger tapping speed across the on-line condition, albeit to a lesser degree than during follow-up or compared to controls. Retrieval two days later indicated a greater off-line gain in motor speed in patients than controls. Moreover, this gain in motor skill performance was negatively correlated to the declarative learning deficit. Our results suggest a differential interaction between procedural and declarative memory systems during acquisition and consolidation of motor sequences in older humans. During acquisition, hippocampal dysfunction attenuates fast learning and thus unmasks the slow and rigid learning curve of striatum-based procedural learning. The stronger gains in the post-consolidation condition in motor skill in CA1 lesioned patients indicate a facilitated consolidation process probably occurring during sleep, and suggest a competitive interaction between the memory systems. These findings might be a reflection of network reorganization and plasticity in older humans and in the presence of CA1 hippocampal pathology. Copyright © 2016 Elsevier Ltd. All rights reserved.

DTI fiber tractography of cerebro-cerebellar pathways and clinical evaluation of ataxia in childhood posterior fossa tumor survivors.

PubMed

Oh, Myung Eun; Driever, Pablo Hernáiz; Khajuria, Rajiv K; Rueckriegel, Stefan Mark; Koustenis, Elisabeth; Bruhn, Harald; Thomale, Ulrich-Wilhelm

2017-01-01

Pediatric posterior fossa (PF) tumor survivors experience long-term motor deficits. Specific cerebrocerebellar connections may be involved in incidence and severity of motor dysfunction. We examined the relationship between long-term ataxia as well as fine motor function and alteration of differential cerebellar efferent and afferent pathways using diffusion tensor imaging (DTI) and tractography. DTI-based tractography was performed in 19 patients (10 pilocytic astrocytoma (PA) and 9 medulloblastoma patients (MB)) and 20 healthy peers. Efferent Cerebello-Thalamo-Cerebral (CTC) and afferent Cerebro-Ponto-Cerebellar (CPC) tracts were reconstructed and analyzed concerning fractional anisotropy (FA) and volumetric measurements. Clinical outcome was assessed with the International Cooperative Ataxia Rating Scale (ICARS). Kinematic parameters of fine motor function (speed, automation, variability, and pressure) were obtained by employing a digitizing graphic tablet. ICARS scores were significantly higher in MB patients than in PA patients. Poorer ICARS scores and impaired fine motor function correlated significantly with volume loss of CTC pathway in MB patients, but not in PA patients. Patients with pediatric post-operative cerebellar mutism syndrome showed higher loss of CTC pathway volume and were more atactic. CPC pathway volume was significantly reduced in PA patients, but not in MB patients. Neither relationship was observed between the CPC pathway and ICARS or fine motor function. There was no group difference of FA values between the patients and healthy peers. Reduced CTC pathway volumes in our cohorts were associated with severity of long-term ataxia and impaired fine motor function in survivors of MBs. We suggest that the CTC pathway seems to play a role in extent of ataxia and fine motor dysfunction after childhood cerebellar tumor treatment. DTI may be a useful tool to identify relevant structures of the CTC pathway and possibly avoid surgically induced long-term neurological sequelae.

Speech, language, and cognitive dysfunction in children with focal epileptiform activity: A follow-up study.

PubMed

Rejnö-Habte Selassie, Gunilla; Hedström, Anders; Viggedal, Gerd; Jennische, Margareta; Kyllerman, Mårten

2010-07-01

We reviewed the medical history, EEG recordings, and developmental milestones of 19 children with speech and language dysfunction and focal epileptiform activity. Speech, language, and neuropsychological assessments and EEG recordings were performed at follow-up, and prognostic indicators were analyzed. Three patterns of language development were observed: late start and slow development, late start and deterioration/regression, and normal start and later regression/deterioration. No differences in test results among these groups were seen, indicating a spectrum of related conditions including Landau-Kleffner syndrome and epileptic language disorder. More than half of the participants had speech and language dysfunction at follow-up. IQ levels, working memory, and processing speed were also affected. Dysfunction of auditory perception in noise was found in more than half of the participants, and dysfunction of auditory attention in all. Dysfunction of communication, oral motor ability, and stuttering were noted in a few. Family history of seizures and abundant epileptiform activity indicated a worse prognosis. Copyright 2010 Elsevier Inc. All rights reserved.

A Qualitative Study of the European Trucking Industry and Logistics Strategies Using the United States Motor Carrier Industry as a Guide

DTIC Science & Technology

1992-09-01

UNITED STATES MOTOR CARRIER INDUSTRY AS A GUIDE THESIS David W. Butler Andrew P. Wilhelm Captain, USAF Captain, USAF AFIT/GLM/LSM/92S-7 Approved for...UNITED STATES MOTOR CARRIER INDUSTRY AS A GUIDE THESIS Presented to the Faculty of the School of Systems and Logistics of the Air Force Institute of...THE EUROPEAN TRUCKING INDUSTRY AND LOGISTICS STRATEGIES USING THE UNITED STATES MOTOR CARRIER INDUSTRY AS A GUIDE I. Introduction General Issue The

Testing of motor unit synchronization model for localized muscle fatigue.

PubMed

Naik, Ganesh R; Kumar, Dinesh K; Yadav, Vivek; Wheeler, Katherine; Arjunan, Sridhar

2009-01-01

Spectral compression of surface electromyogram (sEMG) is associated with onset of localized muscle fatigue. The spectral compression has been explained based on motor unit synchronization theory. According to this theory, motor units are pseudo randomly excited during muscle contraction, and with the onset of muscle fatigue the recruitment pattern changes such that motor unit firings become more synchronized. While this is widely accepted, there is little experimental proof of this phenomenon. This paper has used source dependence measures developed in research related to independent component analysis (ICA) to test this theory.

Synchronization of low- and high-threshold motor units.

PubMed

Defreitas, Jason M; Beck, Travis W; Ye, Xin; Stock, Matt S

2014-04-01

We examined the degree of synchronization for both low- and high-threshold motor unit (MU) pairs at high force levels. MU spike trains were recorded from the quadriceps during high-force isometric leg extensions. Short-term synchronization (between -6 and 6 ms) was calculated for every unique MU pair for each contraction. At high force levels, earlier recruited motor unit pairs (low-threshold) demonstrated relatively low levels of short-term synchronization (approximately 7.3% extra firings than would have been expected by chance). However, the magnitude of synchronization increased significantly and linearly with mean recruitment threshold (reaching 22.1% extra firings for motor unit pairs recruited above 70% MVC). Three potential mechanisms that could explain the observed differences in synchronization across motor unit types are proposed and discussed. Copyright © 2013 Wiley Periodicals, Inc.

Can fast-twitch muscle fibres be selectively recruited during lengthening contractions? Review and applications to sport movements.

PubMed

Chalmers, Gordon R

2008-01-01

Literature examining the recruitment order of motor units during lengthening (eccentric) contractions was reviewed to determine if fast-twitch motor units can be active while lower threshold slow-twitch motor units are not active. Studies utilizing surface electromyogram (EMG) amplitude, single motor unit activity, spike amplitude-frequency analyses, EMG power spectrum, mechanomyographic, and phosphocreatine-to-creatine ratio (PCr/Cr) techniques were reviewed. Only single motor unit and PCr/Cr data were found to be suitable to address the goals of this review. Nine of ten single motor unit studies, examining joint movement velocities up to 225 degrees/s and forces up to 53% of a maximum voluntary contraction, found that the size principle of motor unit recruitment applied during lengthening contractions. Deviation from the size principle was demonstrated by one study examining movements within a small range of low velocities and modest forces, although other studies examining similar low forces and lengthening velocities reported size-ordered recruitment. The PCr/Cr data demonstrated the activation of all fibre types in lengthening maximal contractions. Most evidence indicates that for lengthening contractions of a wide range of efforts and speeds, fast-twitch muscle fibres cannot be selectively recruited without activity of the slow-twitch fibres of the same muscle.

The relationship of motor unit size, firing rate and force.

PubMed

Conwit, R A; Stashuk, D; Tracy, B; McHugh, M; Brown, W F; Metter, E J

1999-07-01

Using a clinical electromyographic (EMG) protocol, motor units were sampled from the quadriceps femoris during isometric contractions at fixed force levels to examine how average motor unit size and firing rate relate to force generation. Mean firing rates (mFRs) and sizes (mean surface-detected motor unit action potential (mS-MUAP) area) of samples of active motor units were assessed at various force levels in 79 subjects. MS-MUAP size increased linearly with increased force generation, while mFR remained relatively constant up to 30% of a maximal force and increased appreciably only at higher force levels. A relationship was found between muscle force and mS-MUAP area (r2 = 0.67), mFR (r2 = 0.38), and the product of mS-MUAP area and mFR (mS-MUAP x mFR) (r2 = 0.70). The results support the hypothesis that motor units are recruited in an orderly manner during forceful contractions, and that in large muscles only at higher levels of contraction ( > 30% MVC) do mFRs increase appreciably. MS-MUAP and mFR can be assessed using clinical EMG techniques and they may provide a physiological basis for analyzing the role of motor units during muscle force generation.

Effect of ageing on the force development in tetanic contractions of motor units in rat medial gastrocnemius muscle.

PubMed

Łochyński, Dawid; Kaczmarek, Dominik; Krutki, Piotr; Celichowski, Jan

2010-09-01

The purpose of this study was to determine the effect of ageing on the rate of force generation of motor units, and the mechanical efficiency of contraction produced by a doublet discharge. The study was carried out on isolated motor units of rat medial gastrocnemius muscle of young (5-10 mo) and two groups of old (24-25 and 28-30 mo) Wistar rats. Motor units were classified into the fast fatigable (FF), fast resistant (FR) and slow (S) ones. The force output and rate of force development were determined for non-doublet unfused tetanic contractions evoked by a series of a constant-rate trains of pulses and corresponding doublet contractions starting with an initial brief interpulse interval of 5 ms, and for maximal tetanic contraction. In FF motor units the rate of force development and the force produced by the doublet discharge increased transiently at the age of 24-25 mo, while in S and FR motor units this increase was observed at the age of 28-30 mo. Age-related decrease in the rate of force development of skeletal muscle cannot be attributed to a decline in efficiency of force production by functioning motor units. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Time-related changes in firing rates are influenced by recruitment threshold and twitch force potentiation in the first dorsal interosseous.

PubMed

Miller, Jonathan D; Herda, Trent J; Trevino, Michael A; Sterczala, Adam J; Ciccone, Anthony B

2017-08-01

What is the central question of this study? The influences of motor unit recruitment threshold and twitch force potentiation on the changes in firing rates during steady-force muscular contractions are not well understood. What is the main finding and its importance? The behaviour of motor units during steady force was influenced by recruitment threshold, such that firing rates decreased for lower-threshold motor units but increased for higher-threshold motor units. In addition, individuals with greater changes in firing rates possessed greater twitch force potentiation. There are contradictory reports regarding changes in motor unit firing rates during steady-force contractions. Inconsistencies are likely to be the result of previous studies disregarding motor unit recruitment thresholds and not examining firing rates on a subject-by-subject basis. It is hypothesized that firing rates are manipulated by twitch force potentiation during contractions. Therefore, in this study we examined time-related changes in firing rates at steady force in relationship to motor unit recruitment threshold in the first dorsal interosseous and the influence of twitch force potentiation on such changes in young versus aged individuals. Subjects performed a 12 s steady-force contraction at 50% maximal voluntary contraction, with evoked twitches before and after the contraction to quantify potentiation. Firing rates, in relationship to recruitment thresholds, were determined at the beginning, middle and end of the steady force. There were no firing rate changes for aged individuals. For the young, firing rates decreased slightly for lower-threshold motor units but increased for higher-threshold motor units. Twitch force potentiation was greater for young than aged subjects, and changes in firing rates were correlated with twitch force potentiation. Thus, individuals with greater increases in firing rates of higher-threshold motor units and decreases in lower-threshold motor units possessed greater twitch force potentiation. Overall, changes in firing rates during brief steady-force contractions are dependent on recruitment threshold and explained in part by twitch force potentiation. Given that firing rate changes were measured in relationship to recruitment threshold, this study illustrates a more complete view of firing rate changes during steady-force contractions. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Comparison of Neurocognitive Outcomes after Carotid Endarterectomy and Carotid Artery Stenting.

PubMed

Kim, Jerry J; Schwartz, Samuel; Wen, Johnny; deVirgilio, Christian; Lobue, Abeline; Walot, Irwin; Koopmann, Matthew; Donayre, Carlos; White, Rodney A

2015-10-01

Cognitive and emotional outcomes after carotid endarterectomy (CEA) and carotid artery stenting with embolic protection device (CAS + EPD) are not clear. Patients were entered prospectively into a United States Food and Drug Administration-approved single-center physician-sponsored investigational device exemption between 2004 and 2010 and received either CEA or CAS + EPD. Patients underwent cognitive testing preprocedure and at 6, 12, and 60 months postprocedure. Cognitive domains assessed included attention, memory, executive, motor function, visual spatial functioning, language, and processing speed. Beck Depression and anxiety scales were also compared. There were a total of 38 patients that met conventional indications for carotid surgery (symptomatic with ≥50% stenosis or asymptomatic with ≥70% stenosis)-12 patients underwent CEA, whereas 26 patients underwent CAS + EPD. Both CEA and CAS + EPD patients showed postprocedure improvement in memory and executive function. No differences were seen at follow-up in regards to emotional dysfunction (depression and anxiety), attention, visual spatial functioning, language, motor function, and processing speed. Only two patients underwent neuropsychiatric testing at 60 months-these CAS + EPD patients showed sustained improvement in memory, visual spatial, and executive functions. In conclusion, cognitive and emotional outcomes were similar between CEA and CAS + EPD patients.

Synchronization of presynaptic input to motor units of tongue, inspiratory intercostal, and diaphragm muscles.

PubMed

Rice, Amber; Fuglevand, Andrew J; Laine, Christopher M; Fregosi, Ralph F

2011-05-01

The respiratory central pattern generator distributes rhythmic excitatory input to phrenic, intercostal, and hypoglossal premotor neurons. The degree to which this input shapes motor neuron activity can vary across respiratory muscles and motor neuron pools. We evaluated the extent to which respiratory drive synchronizes the activation of motor unit pairs in tongue (genioglossus, hyoglossus) and chest-wall (diaphragm, external intercostals) muscles using coherence analysis. This is a frequency domain technique, which characterizes the frequency and relative strength of neural inputs that are common to each of the recorded motor units. We also examined coherence across the two tongue muscles, as our previous work shows that, despite being antagonists, they are strongly coactivated during the inspiratory phase, suggesting that excitatory input from the premotor neurons is distributed broadly throughout the hypoglossal motoneuron pool. All motor unit pairs showed highly correlated activity in the low-frequency range (1-8 Hz), reflecting the fundamental respiratory frequency and its harmonics. Coherence of motor unit pairs recorded either within or across the tongue muscles was similar, consistent with broadly distributed premotor input to the hypoglossal motoneuron pool. Interestingly, motor units from diaphragm and external intercostal muscles showed significantly higher coherence across the 10-20-Hz bandwidth than tongue-muscle units. We propose that the lower coherence in tongue-muscle motor units over this range reflects a larger constellation of presynaptic inputs, which collectively lead to a reduction in the coherence between hypoglossal motoneurons in this frequency band. This, in turn, may reflect the relative simplicity of the respiratory drive to the diaphragm and intercostal muscles, compared with the greater diversity of functions fulfilled by muscles of the tongue.

Longitudinal Associations Between PTSD Symptoms and Dyadic Conflict Communication Following a Severe Motor Vehicle Accident.

PubMed

Fredman, Steffany J; Beck, J Gayle; Shnaider, Philippe; Le, Yunying; Pukay-Martin, Nicole D; Pentel, Kimberly Z; Monson, Candice M; Simon, Naomi M; Marques, Luana

2017-03-01

There are well-documented associations between posttraumatic stress disorder (PTSD) symptoms and intimate relationship impairments, including dysfunctional communication at times of relationship conflict. To date, the extant research on the associations between PTSD symptom severity and conflict communication has been cross-sectional and focused on military and veteran couples. No published work has evaluated the extent to which PTSD symptom severity and communication at times of relationship conflict influence each other over time or in civilian samples. The current study examined the prospective bidirectional associations between PTSD symptom severity and dyadic conflict communication in a sample of 114 severe motor vehicle accident (MVA) survivors in a committed intimate relationship at the time of the accident. PTSD symptom severity and dyadic conflict communication were assessed at 4 and 16weeks post-MVA, and prospective associations were examined using path analysis. Total PTSD symptom severity at 4weeks prospectively predicted greater dysfunctional communication at 16weeks post-MVA but not vice versa. Examination at the level of PTSD symptom clusters revealed that effortful avoidance at 4weeks prospectively predicted greater dysfunctional communication at 16weeks, whereas dysfunctional communication 4weeks after the MVA predicted more severe emotional numbing at 16weeks. Findings highlight the role of PTSD symptoms in contributing to dysfunctional communication and the importance of considering PTSD symptom clusters separately when investigating the dynamic interplay between PTSD symptoms and relationship functioning over time, particularly during the early posttrauma period. Clinical implications for the prevention of chronic PTSD and associated relationship problems are discussed. Copyright © 2016. Published by Elsevier Ltd.

Feeding and gastrointestinal problems in children with cerebral palsy.

PubMed

Erkin, Gulten; Culha, Canan; Ozel, Sumru; Kirbiyik, Eylem Gulsen

2010-09-01

The aim of our study was to identify feeding and gastrointestinal system (GIS) problems in children with cerebral palsy (CP), and to evaluate the relationship between these problems and the severity of CP. A total of 120 children with CP were enrolled consecutively into the study (67 males, 53 females; mean age: 6.0±2.4 years; range: 2-12 years). The children were classified according to the Swedish classification as diplegic, hemiplegic, or quadriplegic. Severity of CP was classified based on the Gross Motor Function Classification System. The amount of time that the caregiver allocated to mealtimes, modifications of the food, as well as feeding and GIS problems was evaluated. Feeding dysfunction was classified as mild, moderate, or severe. Comparisons of GIS and feeding disorders and the severity of CP were carried out using χ test. The results indicated lack of appetite in 46 of the 120 children (38.3%), sialorrhea in 37 (30.8%), constipation in 30 (25%), difficulty in swallowing in 23 (19.2%), and feeding dysfunction in 26 (21.7%). On the basis of the Gross Motor Function Classification System (GMFCS), the incidence of GIS problems and feeding dysfunction was found to be significantly higher in the children classified in the severe group. The time taken to consume meals was significantly longer among children with feeding dysfunction. Feeding and GIS problems are frequent in children with CP, and more marked in those with severe CP. Approximately one fourth of children with CP suffer from feeding dysfunction, and more time has to be allocated to consume meals.

Task and fatigue effects on low-threshold motor units in human hand muscle.

PubMed

Enoka, R M; Robinson, G A; Kossev, A R

1989-12-01

1. The activity of single motor units was recorded in the first dorsal interosseus muscle of human subjects while they performed an isometric ramp-and-hold maneuver. Motor-unit activity was characterized before and after fatigue by the use of a branched bipolar electrode that was positioned subcutaneously over the test muscle. Activity was characterized in terms of the forces of recruitment and derecruitment and the discharge pattern. The purpose was to determine, before and after fatigue, whether motor-unit activity was affected by the direction in which the force was exerted. 2. Regardless of the task during prefatigue trials, interimpulse intervals were 1) more variable during increases or decreases in force than when force was held constant at the target value (4-6% above the recruitment force), and 2) more clustered around an arbitrary central value than would be expected with a normal (Gaussian) distribution. Both effects were seen during the flexion and abduction tasks. The behavior of low-threshold motor units in first dorsal interosseus is thus largely unaffected by the direction of the force exerted by the index finger. The absence of a task (i.e., a direction of force) effect suggests that the resultant force vector about the metacarpophalangeal joint of the index finger is not coded in terms of discrete populations of motor units, but, rather, it is based on the net muscle activity about the joint. 3. Motor-unit behavior during and after fatigue showed that the relatively homogeneous behavior seen before fatigue could be severely disrupted. The fatiguing protocol involved the continuous repetition, to the endurance limit, of a 15-s ramp-and-hold maneuver in which the abduction target force was 50% of maximum and was held for 10-s epochs (ramps up and down were approximately 2 s each). Motor-unit threshold was assessed by the forces of recruitment and derecruitment associated with each cycle of the fatigue test. Changes in recruitment force during the protocol were either minimal or, when present, not systematic. In contrast, the derecruitment force of all units exhibited a marked and progressive increase over the course of the test. 4. After the fatigue test, when the initial threshold tasks were repeated, the behavior of most motor units changed. These changes included the derecruitment of previously active motor units, the recruitment of additional motor units, and an increased discharge variability of units that remained recruited. The variation in recruitment order seemed to be much greater than that reported previously for nonfatiguing conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Motor control differs for increasing and releasing force

PubMed Central

Park, Seoung Hoon; Kwon, MinHyuk; Solis, Danielle; Lodha, Neha

2016-01-01

Control of the motor output depends on our ability to precisely increase and release force. However, the influence of aging on force increase and release remains unknown. The purpose of this study, therefore, was to determine whether force control differs while increasing and releasing force in young and older adults. Sixteen young adults (22.5 ± 4 yr, 8 females) and 16 older adults (75.7 ± 6.4 yr, 8 females) increased and released force at a constant rate (10% maximum voluntary contraction force/s) during an ankle dorsiflexion isometric task. We recorded the force output and multiple motor unit activity from the tibialis anterior (TA) muscle and quantified the following outcomes: 1) variability of force using the SD of force; 2) mean discharge rate and variability of discharge rate of multiple motor units; and 3) power spectrum of the multiple motor units from 0–4, 4–10, 10–35, and 35–60 Hz. Participants exhibited greater force variability while releasing force, independent of age (P < 0.001). Increased force variability during force release was associated with decreased modulation of multiple motor units from 35 to 60 Hz (R2 = 0.38). Modulation of multiple motor units from 35 to 60 Hz was further correlated to the change in mean discharge rate of multiple motor units (r = 0.66) and modulation from 0 to 4 Hz (r = −0.64). In conclusion, these findings suggest that force control is altered while releasing due to an altered modulation of the motor units. PMID:26961104

Developing Interventions for Cancer-Related Cognitive Dysfunction in Childhood Cancer Survivors

PubMed Central

Ullrich, Nicole J.; Whelen, Megan J.; Lange, Beverly J.

2014-01-01

Survivors of childhood cancer frequently experience cancer-related cognitive dysfunction, commonly months to years after treatment for pediatric brain tumors, acute lymphoblastic leukemia (ALL), or tumors involving the head and neck. Risk factors for cancer-related cognitive dysfunction include young age at diagnosis, treatment with cranial irradiation, use of parenteral or intrathecal methotrexate, female sex, and pre-existing comorbidities. Limiting use and reducing doses and volume of cranial irradiation while intensifying chemotherapy have improved survival and reduced the severity of cognitive dysfunction, especially in leukemia. Nonetheless, problems in core functional domains of attention, processing speed, working memory and visual-motor integration continue to compromise quality of life and performance. We review the epidemiology, pathophysiology and assessment of cancer-related cognitive dysfunction, the impact of treatment changes for prevention, and the broad strategies for educational and pharmacological interventions to remediate established cognitive dysfunction following childhood cancer. The increased years of life saved after childhood cancer warrants continued study toward the prevention and remediation of cancer-related cognitive dysfunction, using uniform assessments anchored in functional outcomes. PMID:25080574

Physical Exercise Modulates L-DOPA-Regulated Molecular Pathways in the MPTP Mouse Model of Parkinson's Disease.

PubMed

Klemann, Cornelius J H M; Xicoy, Helena; Poelmans, Geert; Bloem, Bas R; Martens, Gerard J M; Visser, Jasper E

2018-07-01

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc), resulting in motor and non-motor dysfunction. Physical exercise improves these symptoms in PD patients. To explore the molecular mechanisms underlying the beneficial effects of physical exercise, we exposed 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine (MPTP)-treated mice to a four-week physical exercise regimen, and subsequently explored their motor performance and the transcriptome of multiple PD-linked brain areas. MPTP reduced the number of DA neurons in the SNpc, whereas physical exercise improved beam walking, rotarod performance, and motor behavior in the open field. Further, enrichment analyses of the RNA-sequencing data revealed that in the MPTP-treated mice physical exercise predominantly modulated signaling cascades that are regulated by the top upstream regulators L-DOPA, RICTOR, CREB1, or bicuculline/dalfampridine, associated with movement disorders, mitochondrial dysfunction, and epilepsy-related processes. To elucidate the molecular pathways underlying these cascades, we integrated the proteins encoded by the exercise-induced differentially expressed mRNAs for each of the upstream regulators into a molecular landscape, for multiple key brain areas. Most notable was the opposite effect of physical exercise compared to previously reported effects of L-DOPA on the expression of mRNAs in the SN and the ventromedial striatum that are involved in-among other processes-circadian rhythm and signaling involving DA, neuropeptides, and endocannabinoids. Altogether, our findings suggest that physical exercise can improve motor function in PD and may, at the same time, counteract L-DOPA-mediated molecular mechanisms. Further, we hypothesize that physical exercise has the potential to improve non-motor symptoms of PD, some of which may be the result of (chronic) L-DOPA use.

Non-motor symptoms and cardiac innervation in SYNJ1-related parkinsonism.

PubMed

De Rosa, A; Pellegrino, T; Pappatà, S; Lieto, M; Bonifati, V; Palma, V; Topa, A; Santoro, L; Bilo, L; Cuocolo, A; De Michele, G

2016-02-01

PARK20 is a rare autosomal recessive parkinsonism related to the SYNJ1 gene and characterized by early-onset of disease and atypical signs such as supranuclear vertical gaze palsy, dementia, dystonia, and generalized tonic-clonic seizures. Non-motor features and cardiac sympathetic innervation were assessed in two siblings affected by parkinsonism who harboured the homozygous Arg258Gln mutation in the SYNJ1 gene. The Non-Motor Symptoms, the SCOPA-AUT, the Mayo Sleep Questionnaires and polysomnography were used to investigate non-motor signs (NMS), autonomic dysfunction and REM Behavioural Disorder (RBD). Cognitive functions were examined by an extensive battery of neuropsychological tests. In addition, motor and sensory nerve conduction studies and evoked laser potentials were performed. Cardiac sympathetic innervation was assessed in the two patients by (123)I-metaiodobenzylguanidine (MIBG) scintigraphy, computing early and late heart-to-mediastinum (H/M) ratios and myocardial washout rates (WR). Among the non-motor symptoms and autonomic signs, case 1 had cold intolerance, drooling and dysphagia, while case 2 had pain and urinary dysfunction. Both cases showed mood and behavioural disorders. RBD were not found, whereas the neuropsychological assessment revealed a progressive cognitive impairment. Neurophysiological studies revealed no abnormalities. Indexes of cardiac sympathetic innervation in the two patients did not differ from those of control subjects. Our findings expand the phenotypic profile of SYNJ1-related parkinsonism. Preserved cardiac sympathetic function and absence of RBD suggest that PARK20 should be explained by a pathogenic mechanism different from Lewy Body pathology, or that the latter is not as widespread as idiopathic Parkinson's disease. Copyright © 2015 Elsevier Ltd. All rights reserved.

What can autism teach us about the role of sensorimotor systems in higher cognition? New clues from studies on language, action semantics, and abstract emotional concept processing.

PubMed

Moseley, Rachel L; Pulvermüller, Friedemann

2018-03-01

Within the neurocognitive literature there is much debate about the role of the motor system in language, social communication and conceptual processing. We suggest, here, that autism spectrum conditions (ASC) may afford an excellent test case for investigating and evaluating contemporary neurocognitive models, most notably a neurobiological theory of action perception integration where widely-distributed cell assemblies linking neurons in action and perceptual brain regions act as the building blocks of many higher cognitive functions. We review a literature of functional motor abnormalities in ASC, following this with discussion of their neural correlates and aberrancies in language development, explaining how these might arise with reference to the typical formation of cell assemblies linking action and perceptual brain regions. This model gives rise to clear hypotheses regarding language comprehension, and we highlight a recent set of studies reporting differences in brain activation and behaviour in the processing of action-related and abstract-emotional concepts in individuals with ASC. At the neuroanatomical level, we discuss structural differences in long-distance frontotemporal and frontoparietal connections in ASC, such as would compromise information transfer between sensory and motor regions. This neurobiological model of action perception integration may shed light on the cognitive and social-interactive symptoms of ASC, building on and extending earlier proposals linking autistic symptomatology to motor disorder and dysfunction in action perception integration. Further investigating the contribution of motor dysfunction to higher cognitive and social impairment, we suggest, is timely and promising as it may advance both neurocognitive theory and the development of new clinical interventions for this population and others characterised by early and pervasive motor disruption. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Variations in motor unit recruitment patterns occur within and between muscles in the running rat (Rattus norvegicus).

PubMed

Hodson-Tole, E F; Wakeling, J M

2007-07-01

Motor units are generally considered to follow a set, orderly pattern of recruitment within each muscle with activation occurring in the slowest through to the fastest units. A growing body of evidence, however, suggests that recruitment patterns may not always follow such an orderly sequence. Here we investigate whether motor unit recruitment patterns vary within and between the ankle extensor muscles of the rat running at 40 cm s(-1) on a level treadmill. In the past it has been difficult to quantify motor unit recruitment patterns during locomotion; however, recent application of wavelet analysis techniques has made such detailed analysis of motor unit recruitment possible. Here we present methods for quantifying the interplay of fast and slow motor unit recruitment based on their myoelectric signals. Myoelectric data were collected from soleus, plantaris and medial gastrocnemius muscles representing populations of slow, mixed and fast fibres, respectively, and providing a good opportunity to relate myoelectric frequency content to motor unit recruitment patterns. Following wavelet transformation, principal component analysis quantified signal intensity and relative frequency content. Significant differences in signal frequency content occurred between different time points within a stride (P<0.001). We optimised high- and low-frequency wavelets to the major signals from the fast and slow motor units. The goodness-of-fit of the optimised wavelets to the signal intensity was high for all three muscles (r2>0.98). The low-frequency band had a significantly better fit to signals from the soleus muscle (P<0.001), while the high-frequency band had a significantly better fit to the medial gastrocnemius (P<0.001).

Sensory neurons do not induce motor neuron loss in a human stem cell model of spinal muscular atrophy.

PubMed

Schwab, Andrew J; Ebert, Allison D

2014-01-01

Spinal muscular atrophy (SMA) is an autosomal recessive disorder leading to paralysis and early death due to reduced SMN protein. It is unclear why there is such a profound motor neuron loss, but recent evidence from fly and mouse studies indicate that cells comprising the whole sensory-motor circuit may contribute to motor neuron dysfunction and loss. Here, we used induced pluripotent stem cells derived from SMA patients to test whether sensory neurons directly contribute to motor neuron loss. We generated sensory neurons from SMA induced pluripotent stem cells and found no difference in neuron generation or survival, although there was a reduced calcium response to depolarizing stimuli. Using co-culture of SMA induced pluripotent stem cell derived sensory neurons with control induced pluripotent stem cell derived motor neurons, we found no significant reduction in motor neuron number or glutamate transporter boutons on motor neuron cell bodies or neurites. We conclude that SMA sensory neurons do not overtly contribute to motor neuron loss in this human stem cell system.

Neural correlates of the age-related changes in motor sequence learning and motor adaptation in older adults

PubMed Central

King, Bradley R.; Fogel, Stuart M.; Albouy, Geneviève; Doyon, Julien

2013-01-01

As the world's population ages, a deeper understanding of the relationship between aging and motor learning will become increasingly relevant in basic research and applied settings. In this context, this review aims to address the effects of age on motor sequence learning (MSL) and motor adaptation (MA) with respect to behavioral, neurological, and neuroimaging findings. Previous behavioral research investigating the influence of aging on motor learning has consistently reported the following results. First, the initial acquisition of motor sequences is not altered, except under conditions of increased task complexity. Second, older adults demonstrate deficits in motor sequence memory consolidation. And, third, although older adults demonstrate deficits during the exposure phase of MA paradigms, the aftereffects following removal of the sensorimotor perturbation are similar to young adults, suggesting that the adaptive ability of older adults is relatively intact. This paper will review the potential neural underpinnings of these behavioral results, with a particular emphasis on the influence of age-related dysfunctions in the cortico-striatal system on motor learning. PMID:23616757

Morphological Characteristics of Motor Neurons Do Not Determine Their Relative Susceptibility to Degeneration in a Mouse Model of Severe Spinal Muscular Atrophy

PubMed Central

Mutsaers, Chantal A.; Thomson, Derek; Hamilton, Gillian; Parson, Simon H.; Gillingwater, Thomas H.

2012-01-01

Spinal muscular atrophy (SMA) is a leading genetic cause of infant mortality, resulting primarily from the degeneration and loss of lower motor neurons. Studies using mouse models of SMA have revealed widespread heterogeneity in the susceptibility of individual motor neurons to neurodegeneration, but the underlying reasons remain unclear. Data from related motor neuron diseases, such as amyotrophic lateral sclerosis (ALS), suggest that morphological properties of motor neurons may regulate susceptibility: in ALS larger motor units innervating fast-twitch muscles degenerate first. We therefore set out to determine whether intrinsic morphological characteristics of motor neurons influenced their relative vulnerability to SMA. Motor neuron vulnerability was mapped across 10 muscle groups in SMA mice. Neither the position of the muscle in the body, nor the fibre type of the muscle innervated, influenced susceptibility. Morphological properties of vulnerable and disease-resistant motor neurons were then determined from single motor units reconstructed in Thy.1-YFP-H mice. None of the parameters we investigated in healthy young adult mice – including motor unit size, motor unit arbor length, branching patterns, motor endplate size, developmental pruning and numbers of terminal Schwann cells at neuromuscular junctions - correlated with vulnerability. We conclude that morphological characteristics of motor neurons are not a major determinant of disease-susceptibility in SMA, in stark contrast to related forms of motor neuron disease such as ALS. This suggests that subtle molecular differences between motor neurons, or extrinsic factors arising from other cell types, are more likely to determine relative susceptibility in SMA. PMID:23285108

A unifying motor control framework for task-specific dystonia

PubMed Central

Rothwell, John C.; Edwards, Mark J.

2018-01-01

Task-specific dystonia is a movement disorder characterized by the development of a painless loss of dexterity specific to a particular motor skill. This disorder is prevalent among writers, musicians, dancers and athletes. No current treatment is predictably effective and the disorder generally ends the careers of affected individuals. There are a number of limitations with traditional dystonic disease models for task-specific dystonia. We therefore review emerging evidence that the disorder has its origins within normal compensatory mechanisms of a healthy motor system in which the representation and reproduction of motor skill is disrupted. We describe how risk factors for task-specific dystonia can be stratified and translated into mechanisms of dysfunctional motor control. The proposed model aims to define new directions for experimental research and stimulate therapeutic advances for this highly disabling disorder. PMID:29104291

In Vivo Imaging of Human Sarcomere Twitch Dynamics in Individual Motor Units

PubMed Central

Sanchez, Gabriel N.; Sinha, Supriyo; Liske, Holly; Chen, Xuefeng; Nguyen, Viet; Delp, Scott L.; Schnitzer, Mark J.

2017-01-01

SUMMARY Motor units comprise a pre-synaptic motor neuron and multiple post-synaptic muscle fibers. Many movement disorders disrupt motor unit contractile dynamics and the structure of sarcomeres, skeletal muscle’s contractile units. Despite the motor unit’s centrality to neuromuscular physiology, no extant technology can image sarcomere twitch dynamics in live humans. We created a wearable microscope equipped with a microendoscope for minimally invasive observation of sarcomere lengths and contractile dynamics in any major skeletal muscle. By electrically stimulating twitches via the microendoscope and visualizing the sarcomere displacements, we monitored single motor unit contractions in soleus and vastus lateralis muscles of healthy individuals. Control experiments verified that these evoked twitches involved neuromuscular transmission and faithfully reported muscle force generation. In post-stroke patients with spasticity of the biceps brachii, we found involuntary microscopic contractions and sarcomere length abnormalities. The wearable microscope facilitates exploration of many basic and disease-related neuromuscular phenomena never visualized before in live humans. PMID:26687220

Eccentric muscle damage has variable effects on motor unit recruitment thresholds and discharge patterns in elbow flexor muscles.

PubMed

Dartnall, Tamara J; Rogasch, Nigel C; Nordstrom, Michael A; Semmler, John G

2009-07-01

The purpose of this study was to determine the effect of eccentric muscle damage on recruitment threshold force and repetitive discharge properties of low-threshold motor units. Ten subjects performed four tasks involving isometric contraction of elbow flexors while electromyographic (EMG) data were recorded from human biceps brachii and brachialis muscles. Tasks were 1) maximum voluntary contraction (MVC); 2) constant-force contraction at various submaximal targets; 3) motor unit recruitment threshold task; and 4) minimum motor unit discharge rate task. These tasks were performed on three separate days before, immediately after, and 24 h after eccentric exercise of elbow flexor muscles. MVC force declined (42%) immediately after exercise and remained depressed (29%) 24 h later, indicative of muscle damage. Mean motor unit recruitment threshold for biceps brachii was 8.4+/-4.2% MVC, (n=34) before eccentric exercise, and was reduced by 41% (5.0+/-3.0% MVC, n=34) immediately after and by 39% (5.2+/-2.5% MVC, n=34) 24 h after exercise. No significant changes in motor unit recruitment threshold were observed in the brachialis muscle. However, for the minimum tonic discharge rate task, motor units in both muscles discharged 11% faster (10.8+/-2.0 vs. 9.7+/-1.7 Hz) immediately after (n=29) exercise compared with that before (n=32). The minimum discharge rate variability was greater in brachialis muscle immediately after exercise (13.8+/-3.1%) compared with that before (11.9+/-3.1%) and 24 h after exercise (11.7+/-2.4%). No significant changes in minimum discharge rate variability were observed in the biceps brachii motor units after exercise. These results indicate that muscle damage from eccentric exercise alters motor unit recruitment thresholds for >or=24 h, but the effect is not the same in the different elbow flexor muscles.

Human mutant huntingtin disrupts vocal learning in transgenic songbirds.

PubMed

Liu, Wan-Chun; Kohn, Jessica; Szwed, Sarah K; Pariser, Eben; Sepe, Sharon; Haripal, Bhagwattie; Oshimori, Naoki; Marsala, Martin; Miyanohara, Atsushi; Lee, Ramee

2015-11-01

Speech and vocal impairments characterize many neurological disorders. However, the neurogenetic mechanisms of these disorders are not well understood, and current animal models do not have the necessary circuitry to recapitulate vocal learning deficits. We developed germline transgenic songbirds, zebra finches (Taneiopygia guttata) expressing human mutant huntingtin (mHTT), a protein responsible for the progressive deterioration of motor and cognitive function in Huntington's disease (HD). Although generally healthy, the mutant songbirds had severe vocal disorders, including poor vocal imitation, stuttering, and progressive syntax and syllable degradation. Their song abnormalities were associated with HD-related neuropathology and dysfunction of the cortical-basal ganglia (CBG) song circuit. These transgenics are, to the best of our knowledge, the first experimentally created, functional mutant songbirds. Their progressive and quantifiable vocal disorder, combined with circuit dysfunction in the CBG song system, offers a model for genetic manipulation and the development of therapeutic strategies for CBG-related vocal and motor disorders.

Emerging Common Molecular Pathways for Primary Dystonia

PubMed Central

LeDoux, Mark S; Dauer, William T; Warner, Thomas T

2013-01-01

Background The dystonias are a group of hyperkinetic movement disorders whose principal cause is neuron dysfunction at one or more interconnected nodes of the motor system. The study of genes and proteins which cause familial dystonia provides critical information about the cellular pathways involved in this dysfunction which disrupts the motor pathways at systems level. In recent years study of the increasing number of DYT genes has implicated a number of cell functions which appear to be involved in the pathogenesis of dystonia. Methods Review of literature published in English language publications available on Pubmed relating to the genetics and cellular pathology of dystonia Results and Conclusions Numerous potential pathogenetic mechanisms have been identified. We describe those which fall into three emerging thematic groups: cell cycle and transcriptional regulation in the nucleus, endoplasmic reticulum and nuclear envelope function, and control of synaptic function. PMID:23893453

Intestinal crosstalk: a new paradigm for understanding the gut as the "motor" of critical illness.

PubMed

Clark, Jessica A; Coopersmith, Craig M

2007-10-01

For more than 20 years, the gut has been hypothesized to be the "motor" of multiple organ dysfunction syndrome. As critical care research has evolved, there have been multiple mechanisms by which the gastrointestinal tract has been proposed to drive systemic inflammation. Many of these disparate mechanisms have proved to be important in the origin and propagation of critical illness. However, this has led to an unusual situation where investigators describing the gut as a "motor" revving the systemic inflammatory response syndrome are frequently describing wholly different processes to support their claim (i.e., increased apoptosis, altered tight junctions, translocation, cytokine production, crosstalk with commensal bacteria, etc). The purpose of this review is to present a unifying theory as to how the gut drives critical illness. Although the gastrointestinal tract is frequently described simply as "the gut," it is actually made up of (1) an epithelium; (2) a diverse and robust immune arm, which contains most of the immune cells in the body; and (3) the commensal bacteria, which contain more cells than are present in the entire host organism. We propose that the intestinal epithelium, the intestinal immune system, and the intestine's endogenous bacteria all play vital roles driving multiple organ dysfunction syndrome, and the complex crosstalk between these three interrelated portions of the gastrointestinal tract is what cumulatively makes the gut a "motor" of critical illness.

Loss of Mitochondrial Ndufs4 in Striatal Medium Spiny Neurons Mediates Progressive Motor Impairment in a Mouse Model of Leigh Syndrome.

PubMed

Chen, Byron; Hui, Jessica; Montgomery, Kelsey S; Gella, Alejandro; Bolea, Irene; Sanz, Elisenda; Palmiter, Richard D; Quintana, Albert

2017-01-01

Inability of mitochondria to generate energy leads to severe and often fatal myoencephalopathies. Among these, Leigh syndrome (LS) is one of the most common childhood mitochondrial diseases; it is characterized by hypotonia, failure to thrive, respiratory insufficiency and progressive mental and motor dysfunction, leading to early death. Basal ganglia nuclei, including the striatum, are affected in LS patients. However, neither the identity of the affected cell types in the striatum nor their contribution to the disease has been established. Here, we used a mouse model of LS lacking Ndufs4 , a mitochondrial complex I subunit, to confirm that loss of complex I, but not complex II, alters respiration in the striatum. To assess the role of striatal dysfunction in the pathology, we selectively inactivated Ndufs4 in the striatal medium spiny neurons (MSNs), which account for over 95% of striatal neurons. Our results show that lack of Ndufs4 in MSNs causes a non-fatal progressive motor impairment without affecting the cognitive function of mice. Furthermore, no inflammatory responses or neuronal loss were observed up to 6 months of age. Hence, complex I deficiency in MSNs contributes to the motor deficits observed in LS, but not to the neural degeneration, suggesting that other neuronal populations drive the plethora of clinical signs in LS.

Motor and Executive Function Profiles in Adult Residents ...

EPA Pesticide Factsheets

Objective: Exposure to elevated levels of manganese (Mn) may be associated with tremor, motor and executive dysfunction (EF), clinically resembling Parkinson’s disease (PD). PD research has identified tremor-dominant (TD) and non-tremor dominant (NTD) profiles. NTD PD presents with bradykinesia, rigidity, and postural sway, and is associated with EF impairment with lower quality of life (QoL). Presence and impact of tremor, motor, and executive dysfunction profiles on health-related QoL and life satisfaction were examined in air-Mn exposed residents of two Ohio, USA towns. Participants and Methods: From two Ohio towns exposed to air-Mn, 186 residents (76 males) aged 30-75 years were administered measures of EF (Animal Naming, ACT, Rey-O Copy, Stroop Color-Word, and Trails B), motor and tremor symptoms (UPDRS), QoL (BRFSS), life satisfaction (SWLS), and positive symptom distress (SCL-90-R). Air-Mn exposure in the two towns was modeled with 10 years of air-monitoring data. Cluster analyses detected the presence of symptom profiles by grouping together residents with similar scores on these measures. Results: Overall, mean air-Mn concentration for the two towns was 0.53 µg/m3 (SD=.92). Two-step cluster analyses identified TD and NTD symptom profiles. Residents in the NTD group lacked EF impairment; EF impairment represented a separate profile. An unimpaired group also emerged. The NTD and EF impairment groups were qualitatively similar, with relatively lo

A Novel Framework Based on FastICA for High Density Surface EMG Decomposition

PubMed Central

Chen, Maoqi; Zhou, Ping

2015-01-01

This study presents a progressive FastICA peel-off (PFP) framework for high density surface electromyogram (EMG) decomposition. The novel framework is based on a shift-invariant model for describing surface EMG. The decomposition process can be viewed as progressively expanding the set of motor unit spike trains, which is primarily based on FastICA. To overcome the local convergence of FastICA, a “peel off” strategy (i.e. removal of the estimated motor unit action potential (MUAP) trains from the previous step) is used to mitigate the effects of the already identified motor units, so more motor units can be extracted. Moreover, a constrained FastICA is applied to assess the extracted spike trains and correct possible erroneous or missed spikes. These procedures work together to improve the decomposition performance. The proposed framework was validated using simulated surface EMG signals with different motor unit numbers (30, 70, 91) and signal to noise ratios (SNRs) (20, 10, 0 dB). The results demonstrated relatively large numbers of extracted motor units and high accuracies (high F1-scores). The framework was also tested with 111 trials of 64-channel electrode array experimental surface EMG signals during the first dorsal interosseous (FDI) muscle contraction at different intensities. On average 14.1 ± 5.0 motor units were identified from each trial of experimental surface EMG signals. PMID:25775496

Variable-Displacement Hydraulic Drive Unit

NASA Technical Reports Server (NTRS)

Lang, D. J.; Linton, D. J.; Markunas, A.

1986-01-01

Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

Motor unit number estimation and quantitative needle electromyography in stroke patients.

PubMed

Kouzi, Ioanna; Trachani, Eftichia; Anagnostou, Evangelos; Rapidi, Christina-Anastasia; Ellul, John; Sakellaropoulos, George C; Chroni, Elisabeth

2014-12-01

To evaluate the effect of upper motor neuron damage upon motor units' function by means of two separate and supplementary electrophysiological methods. The abductor digiti minimi muscle of the non-paretic and the paretic side was studied in forty-six stroke patients with (a) motor unit number estimation (MUNE) - adapted multiple point stimulation method and (b) computerized quantitative needle electromyography (EMG) assessing the configuration of voluntary recruited motor unit potentials. Main outcome comparisons were focused on differences between non-paretic and paretic side. On the affected hands mean MUNE value was significantly lower and mean area of the surface recorded single motor unit potentials was significantly larger than the corresponding ones on the non-paretic hands. EMG findings did not reveal remarkable differences between the two sides. Neither severity nor chronicity of stroke was related to MUNE or EMG parameters. MUNE results, which suggested reduced motor unit numbers in stroke patients, in conjunction with the normal EMG features in these same muscles has given rise to different interpretations. In a clinical setting, reinnervation type changes in the EMG similar to that occurring in neuronopathies or axonal neuropathies should not be expected in muscles with central neurogenic lesion. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interplay of upper and lower motor neuron degeneration in amyotrophic lateral sclerosis.

PubMed

de Carvalho, Mamede; Poliakov, Artiom; Tavares, Cristiano; Swash, Michael

2017-11-01

We studied motor unit recruitment to test a new method to identify motor unit firing rate (FR) variability. We studied 68 ALS patients, with and without upper neuron signs (UMN) in lower limbs, 24 patients with primary lateral sclerosis (PLS), 13 patients with spinal cord lesion and 39 normal subjects. All recordings were made from tibialis anterior muscles of normal strength. Subjects performed a very slight contraction in order to activate 2 motor units in each recording. 5-7 motor unit pairs were recorded in each subject. Mean consecutive differences (MCD) were calculated for each pair of potentials. The mean MCD for each muscle was estimated as the mean from the total number of pairs recorded. Ap value<0.01 was accepted as significant. MCD of FR frequency was less in the subjects with spinal cord lesion and PLS. In addition, the FR frequency of the 1st motor unit in a pair of units was markedly reduced in PLS, and in subjects with spinal cord lesions. These results support a lower threshold and reduced FR fluctuation in spinal motor neurons of spastic patients. This method can be developed for detection of UMN lesions. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Large motor units are selectively affected following a stroke.

PubMed

Lukács, M; Vécsei, L; Beniczky, S

2008-11-01

Previous studies have revealed a loss of functioning motor units in stroke patients. However, it remained unclear whether the motor units are affected randomly or in some specific pattern. We assessed whether there is a selective loss of the large (high recruitment threshold) or the small (low recruitment threshold) motor units following a stroke. Forty-five stroke patients and 40 healthy controls participated in the study. Macro-EMG was recorded from the abductor digiti minimi muscle at two levels of force output (low and high). The median macro motor unit potential (macro-MUP) amplitude on the paretic side was compared with those on the unaffected side and in the controls. In the control group and on the unaffected side, the macro-MUPs were significantly larger at the high force output than at the low one. However, on the paretic side the macro-MUPs at the high force output had the same amplitude as those recorded at the low force output. These changes correlated with the severity of the paresis. Following a stroke, there is a selective functional loss of the large, high-threshold motor units. These changes are related to the severity of the symptoms. Our findings furnish further insight into the pathophysiology of the motor deficit following a stroke.

49 CFR 1572.201 - Transportation of hazardous materials via commercial motor vehicle from Canada or Mexico to and...

Code of Federal Regulations, 2010 CFR

2010-10-01

... commercial motor vehicle from Canada or Mexico to and within the United States. 1572.201 Section 1572.201... ASSESSMENTS Transportation of Hazardous Materials From Canada or Mexico To and Within the United States by... Mexico to and within the United States. (a) Applicability. This section applies to commercial motor...

Recruitment of motor units in the medial gastrocnemius muscle during human quiet standing: is recruitment intermittent? What triggers recruitment?

PubMed Central

Loram, Ian D.; Muceli, Silvia; Merletti, Roberto; Farina, Dario

2012-01-01

The recruitment and the rate of discharge of motor units are determinants of muscle force. Within a motoneuron pool, recruitment and rate coding of individual motor units might be controlled independently, depending on the circumstances. In this study, we tested whether, during human quiet standing, the force of the medial gastrocnemius (MG) muscle is predominantly controlled by recruitment or rate coding. If MG control during standing was mainly due to recruitment, then we further asked what the trigger mechanism is. Is it determined internally, or is it related to body kinematics? While seven healthy subjects stood quietly, intramuscular electromyograms were recorded from the MG muscle with three pairs of wire electrodes. The number of active motor units and their mean discharge rate were compared for different sway velocities and positions. Motor unit discharges occurred more frequently when the body swayed faster and forward (Pearson R = 0.63; P < 0.0001). This higher likelihood of observing motor unit potentials was explained chiefly by the recruitment of additional units. During forward body shifts, the median number of units detected increased from 3 to 11 (P < 0.0001), whereas the discharge rate changed from 8 ± 1.1 (mean ± SD) to 10 ± 0.9 pulses/s (P = 0.001). Strikingly, motor units did not discharge continuously throughout standing. They were recruited within individual, forward sways and intermittently, with a modal rate of two recruitments per second. This modal rate is consistent with previous circumstantial evidence relating the control of standing to an intrinsic, higher level planning process. PMID:21994258

PyMUS: Python-Based Simulation Software for Virtual Experiments on Motor Unit System

PubMed Central

Kim, Hojeong; Kim, Minjung

2018-01-01

We constructed a physiologically plausible computationally efficient model of a motor unit and developed simulation software that allows for integrative investigations of the input–output processing in the motor unit system. The model motor unit was first built by coupling the motoneuron model and muscle unit model to a simplified axon model. To build the motoneuron model, we used a recently reported two-compartment modeling approach that accurately captures the key cell-type-related electrical properties under both passive conditions (somatic input resistance, membrane time constant, and signal attenuation properties between the soma and the dendrites) and active conditions (rheobase current and afterhyperpolarization duration at the soma and plateau behavior at the dendrites). To construct the muscle unit, we used a recently developed muscle modeling approach that reflects the experimentally identified dependencies of muscle activation dynamics on isometric, isokinetic and dynamic variation in muscle length over a full range of stimulation frequencies. Then, we designed the simulation software based on the object-oriented programing paradigm and developed the software using open-source Python language to be fully operational using graphical user interfaces. Using the developed software, separate simulations could be performed for a single motoneuron, muscle unit and motor unit under a wide range of experimental input protocols, and a hierarchical analysis could be performed from a single channel to the entire system behavior. Our model motor unit and simulation software may represent efficient tools not only for researchers studying the neural control of force production from a cellular perspective but also for instructors and students in motor physiology classroom settings. PMID:29695959

PyMUS: Python-Based Simulation Software for Virtual Experiments on Motor Unit System.

PubMed

Kim, Hojeong; Kim, Minjung

2018-01-01

We constructed a physiologically plausible computationally efficient model of a motor unit and developed simulation software that allows for integrative investigations of the input-output processing in the motor unit system. The model motor unit was first built by coupling the motoneuron model and muscle unit model to a simplified axon model. To build the motoneuron model, we used a recently reported two-compartment modeling approach that accurately captures the key cell-type-related electrical properties under both passive conditions (somatic input resistance, membrane time constant, and signal attenuation properties between the soma and the dendrites) and active conditions (rheobase current and afterhyperpolarization duration at the soma and plateau behavior at the dendrites). To construct the muscle unit, we used a recently developed muscle modeling approach that reflects the experimentally identified dependencies of muscle activation dynamics on isometric, isokinetic and dynamic variation in muscle length over a full range of stimulation frequencies. Then, we designed the simulation software based on the object-oriented programing paradigm and developed the software using open-source Python language to be fully operational using graphical user interfaces. Using the developed software, separate simulations could be performed for a single motoneuron, muscle unit and motor unit under a wide range of experimental input protocols, and a hierarchical analysis could be performed from a single channel to the entire system behavior. Our model motor unit and simulation software may represent efficient tools not only for researchers studying the neural control of force production from a cellular perspective but also for instructors and students in motor physiology classroom settings.

Recruitment of motor units in the medial gastrocnemius muscle during human quiet standing: is recruitment intermittent? What triggers recruitment?

PubMed

Vieira, Taian M M; Loram, Ian D; Muceli, Silvia; Merletti, Roberto; Farina, Dario

2012-01-01

The recruitment and the rate of discharge of motor units are determinants of muscle force. Within a motoneuron pool, recruitment and rate coding of individual motor units might be controlled independently, depending on the circumstances. In this study, we tested whether, during human quiet standing, the force of the medial gastrocnemius (MG) muscle is predominantly controlled by recruitment or rate coding. If MG control during standing was mainly due to recruitment, then we further asked what the trigger mechanism is. Is it determined internally, or is it related to body kinematics? While seven healthy subjects stood quietly, intramuscular electromyograms were recorded from the MG muscle with three pairs of wire electrodes. The number of active motor units and their mean discharge rate were compared for different sway velocities and positions. Motor unit discharges occurred more frequently when the body swayed faster and forward (Pearson R = 0.63; P < 0.0001). This higher likelihood of observing motor unit potentials was explained chiefly by the recruitment of additional units. During forward body shifts, the median number of units detected increased from 3 to 11 (P < 0.0001), whereas the discharge rate changed from 8 ± 1.1 (mean ± SD) to 10 ± 0.9 pulses/s (P = 0.001). Strikingly, motor units did not discharge continuously throughout standing. They were recruited within individual, forward sways and intermittently, with a modal rate of two recruitments per second. This modal rate is consistent with previous circumstantial evidence relating the control of standing to an intrinsic, higher level planning process.

Influence of prolonged static stretching on motor unit firing properties.

PubMed

Ye, Xin; Beck, Travis W; Wages, Nathan P

2016-05-01

The purpose of this study was to examine the influence of a stretching intervention on motor control strategy of the biceps brachii muscle. Ten men performed twelve 100-s passive static stretches of the biceps brachii. Before and after the intervention, isometric strength was tested during maximal voluntary contractions (MVCs) of the elbow flexors. Subjects also performed trapezoid isometric contractions at 30% and 70% of MVC. Surface electromyographic signals from the submaximal contractions were decomposed into individual motor unit action potential trains. Linear regression analysis was used to examine the relationship between motor unit mean firing rate and recruitment threshold. The stretching intervention caused significant decreases in y-intercepts of the linear regression lines. In addition, linear slopes at both intensities remained unchanged. Despite reduced motor unit firing rates following the stretches, the motor control scheme remained unchanged. © 2016 Wiley Periodicals, Inc.

Neuromotor control in chronic obstructive pulmonary disease.

PubMed

Mantilla, Carlos B; Sieck, Gary C

2013-05-01

Neuromotor control of skeletal muscles, including respiratory muscles, is ultimately dependent on the structure and function of the motor units (motoneurons and the muscle fibers they innervate) comprising the muscle. In most muscles, considerable diversity of contractile and fatigue properties exists across motor units, allowing a range of motor behaviors. In diseases such as chronic obstructive pulmonary disease (COPD), there may be disproportional primary (disease related) or secondary effects (related to treatment or other concomitant factors) on the size and contractility of specific muscle fiber types that would influence the relative contribution of different motor units. For example, with COPD there is a disproportionate atrophy of type IIx and/or IIb fibers that comprise more fatigable motor units. Thus fatigue resistance may appear to improve, while overall motor performance (e.g., 6-min walk test) and endurance (e.g., reduced aerobic exercise capacity) are diminished. There are many coexisting factors that might also influence motor performance. For example, in COPD patients, there may be concomitant hypoxia and/or hypercapnia, physical inactivity and unloading of muscles, and corticosteroid treatment, all of which may disproportionately affect specific muscle fiber types, thereby influencing neuromotor control. Future studies should address how plasticity in motor units can be harnessed to mitigate the functional impact of COPD-induced changes.

Acute lower motor neuron tetraparesis.

PubMed

Añor, Sònia

2014-11-01

Flaccid nonambulatory tetraparesis or tetraplegia is an infrequent neurologic presentation; it is characteristic of neuromuscular disease (lower motor neuron [LMN] disease) rather than spinal cord disease. Paresis beginning in the pelvic limbs and progressing to the thoracic limbs resulting in flaccid tetraparesis or tetraplegia within 24 to 72 hours is a common presentation of peripheral nerve or neuromuscular junction disease. Complete body flaccidity develops with severe decrease or complete loss of spinal reflexes in pelvic and thoracic limbs. Animals with acute generalized LMN tetraparesis commonly show severe motor dysfunction in all limbs and severe generalized weakness in all muscles. Copyright © 2014 Elsevier Inc. All rights reserved.

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise.

PubMed

Macgregor, Lewis J; Hunter, Angus M

2018-01-01

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p <0.001) and rate of torque development (495.7 ± 136.9 Nm.s-1 vs. 163.4 ± 163.7 Nm.s-1; p <0.001) 48h post-exercise. Mean motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p <0.01) in high-threshold motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; p< 0.001) 48h post-exercise. The firing rate of high-threshold motor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures.

Speech motor development: Integrating muscles, movements, and linguistic units.

PubMed

Smith, Anne

2006-01-01

A fundamental problem for those interested in human communication is to determine how ideas and the various units of language structure are communicated through speaking. The physiological concepts involved in the control of muscle contraction and movement are theoretically distant from the processing levels and units postulated to exist in language production models. A review of the literature on adult speakers suggests that they engage complex, parallel processes involving many units, including sentence, phrase, syllable, and phoneme levels. Infants must develop multilayered interactions among language and motor systems. This discussion describes recent studies of speech motor performance relative to varying linguistic goals during the childhood, teenage, and young adult years. Studies of the developing interactions between speech motor and language systems reveal both qualitative and quantitative differences between the developing and the mature systems. These studies provide an experimental basis for a more comprehensive theoretical account of how mappings between units of language and units of action are formed and how they function. Readers will be able to: (1) understand the theoretical differences between models of speech motor control and models of language processing, as well as the nature of the concepts used in the two different kinds of models, (2) explain the concept of coarticulation and state why this phenomenon has confounded attempts to determine the role of linguistic units, such as syllables and phonemes, in speech production, (3) describe the development of speech motor performance skills and specify quantitative and qualitative differences between speech motor performance in children and adults, and (4) describe experimental methods that allow scientists to study speech and limb motor control, as well as compare units of action used to study non-speech and speech movements.

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise

PubMed Central

Macgregor, Lewis J.

2018-01-01

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p <0.001) and rate of torque development (495.7 ± 136.9 Nm.s-1 vs. 163.4 ± 163.7 Nm.s-1; p <0.001) 48h post-exercise. Mean motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p <0.01) in high-threshold motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; p< 0.001) 48h post-exercise. The firing rate of high-threshold motor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures. PMID:29630622

Dealing with time-varying recruitment and length in Hill-type muscle models.

PubMed

Hamouda, Ahmed; Kenney, Laurence; Howard, David

2016-10-03

Hill-type muscle models are often used in muscle simulation studies and also in the design and virtual prototyping of functional electrical stimulation systems. These models have to behave in a sufficiently realistic manner when recruitment level and contractile element (CE) length change continuously. For this reason, most previous models have used instantaneous CE length in the muscle׳s force vs. length (F-L) relationship, but thereby neglect the instability problem on the descending limb (i.e. region of negative slope) of the F-L relationship. Ideally CE length at initial recruitment should be used but this requires a multiple-motor-unit muscle model to properly account for different motor-units having different initial lengths when recruited. None of the multiple-motor-unit models reported in the literature have used initial CE length in the muscle׳s F-L relationship, thereby also neglecting the descending limb instability problem. To address the problem of muscle modelling for continuously varying recruitment and length, and hence different values of initial CE length for different motor-units, a new multiple-motor-unit muscle model is presented which considers the muscle to comprise 1000 individual Hill-type virtual motor-units, which determine the total isometric force. Other parts of the model (F-V relationship and passive elements) are not dependent on the initial CE length and, therefore, they are implemented for the muscle as a whole rather than for the individual motor-units. The results demonstrate the potential errors introduced by using a single-motor-unit model and also the instantaneous CE length in the F-L relationship, both of which are common in FES control studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Motor unit recruitment and firing rate in medial gastrocnemius muscles during external perturbations in standing in humans.

PubMed

Pollock, C L; Ivanova, T D; Hunt, M A; Garland, S J

2014-10-01

There is limited investigation of the interaction between motor unit recruitment and rate coding for modulating force during standing or responding to external perturbations. Fifty-seven motor units were recorded from the medial gastrocnemius muscle with intramuscular electrodes in response to external perturbations in standing. Anteriorly directed perturbations were generated by applying loads in 0.45-kg increments at the pelvis every 25-40 s until 2.25 kg was maintained. Motor unit firing rate was calculated for the initial recruitment load and all subsequent loads during two epochs: 1) dynamic response to perturbation directly following each load drop and 2) maintenance of steady state between perturbations. Joint kinematics and surface electromyography (EMG) from lower extremities and force platform measurements were assessed. Application of the external loads resulted in a significant forward progression of the anterior-posterior center of pressure (AP COP) that was accompanied by modest changes in joint angles (<3°). Surface EMG increased more in medial gastrocnemius than in the other recorded muscles. At initial recruitment, motor unit firing rate immediately after the load drop was significantly lower than during subsequent load drops or during the steady state at the same load. There was a modest increase in motor unit firing rate immediately after the load drop on subsequent load drops associated with regaining balance. There was no effect of maintaining balance with increased load and forward progression of the AP COP on steady-state motor unit firing rate. The medial gastrocnemius utilized primarily motor unit recruitment to achieve the increased levels of activation necessary to maintain standing in the presence of external loads. Copyright © 2014 the American Physiological Society.

The expanding universe of disorders of the basal ganglia.

PubMed

Obeso, Jose A; Rodriguez-Oroz, Maria C; Stamelou, Maria; Bhatia, Kailash P; Burn, David J

2014-08-09

The basal ganglia were originally thought to be associated purely with motor control. However, dysfunction and pathology of different regions and circuits are now known to give rise to many clinical manifestations beyond the association of basal ganglia dysfunction with movement disorders. Moreover, disorders that were thought to be caused by dysfunction of the basal ganglia only, such as Parkinson's disease and Huntington's disease, have diverse abnormalities distributed not only in the brain but also in the peripheral and autonomic nervous systems; this knowledge poses new questions and challenges. We discuss advances and the unanswered questions, and ways in which progress might be made. Copyright © 2014 Elsevier Ltd. All rights reserved.

Electroacupuncture remediates glial dysfunction and ameliorates neurodegeneration in the astrocytic α-synuclein mutant mouse model.

PubMed

Deng, Jiahui; Lv, E; Yang, Jian; Gong, Xiaoli; Zhang, Wenzhong; Liang, Xibin; Wang, Jiazeng; Jia, Jun; Wang, Xiaomin

2015-05-28

The acupuncture or electroacupuncture (EA) shows the therapeutic effect on various neurodegenerative diseases. This effect was thought to be partially achieved by its ability to alleviate existing neuroinflammation and glial dysfunction. In this study, we systematically investigated the effect of EA on abnormal neurochemical changes and motor symptoms in a mouse neurodegenerative disease model. The transgenic mouse which expresses a mutant α-synuclein (α-syn) protein, A53T α-syn, in brain astrocytic cells was used. These mice exhibit extensive neuroinflammatory and motor phenotypes of neurodegenerative disorders. In this study, the effects of EA on these phenotypic changes were examined in these mice. EA improved the movement detected in multiple motor tests in A53T mutant mice. At the cellular level, EA significantly reduced the activation of microglia and prevented the loss of dopaminergic neurons in the midbrain and motor neurons in the spinal cord. At the molecular level, EA suppressed the abnormal elevation of proinflammatory factors (tumor necrosis factor-α and interleukin-1β) in the striatum and midbrain of A53T mice. In contrast, EA increased striatal and midbrain expression of a transcription factor, nuclear factor E2-related factor 2, and its downstream antioxidants (heme oxygenase-1 and glutamate-cysteine ligase modifier subunits). These results suggest that EA possesses the ability to ameliorate mutant α-syn-induced motor abnormalities. This ability may be due to that EA enhances both anti-inflammatory and antioxidant activities and suppresses aberrant glial activation in the diseased sites of brains.

Role of Ocimum basilicum L. in prevention of ischemia and reperfusion-induced cerebral damage, and motor dysfunctions in mice brain.

PubMed

Bora, Kundan Singh; Arora, Shruti; Shri, Richa

2011-10-11

The genus Ocimum (Lamiaceae) has a long history of use as culinary and medicinal herbs. Many species are used for their antioxidant and neuroprotective activity in various parts of the world. Ocimum basilicum Linn. has been used traditionally for the treatment of anxiety, diabetes, cardiovascular diseases, headaches, nerve pain, as anticonvulsant and anti-inflammatory, and used in a variety of neurodegenerative disorders. The present study is designed to investigate the effect of ethyl acetate extract of Ocimum basilicum leaves on ischemia and reperfusion-induced cerebral damage, and motor dysfunctions in mice. Global cerebral ischemia was induced by bilateral carotid artery occlusion for 15 min followed by reperfusion for 24h. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. The concentration of thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) content was determined by colorimetric assay. Short-term memory was evaluated using elevated plus-maze. Inclined beam walking was employed to assess motor coordination. Bilateral carotid artery occlusion followed by reperfusion produced significant increase in cerebral infarct size and lipid peroxidation (TBARS), and reduced GSH content, and impaired short-term memory and motor coordination. Pre-treatment with standardized ethyl acetate extract of Ocimum basilicum (100 and 200mg/kg, p.o.) markedly reduced cerebral infarct size and lipid peroxidation, restored GSH content, and attenuated impairment in short-term memory and motor coordination. The results of the study suggest that Ocimum basilicum could be useful clinically in the prevention of stroke. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

A ketogenic diet as a potential novel therapeutic intervention in amyotrophic lateral sclerosis.

PubMed

Zhao, Zhong; Lange, Dale J; Voustianiouk, Andrei; MacGrogan, Donal; Ho, Lap; Suh, Jason; Humala, Nelson; Thiyagarajan, Meenakshisundaram; Wang, Jun; Pasinetti, Giulio M

2006-04-03

The cause of neuronal death in amyotrophic lateral sclerosis (ALS) is uncertain but mitochondrial dysfunction may play an important role. Ketones promote mitochondrial energy production and membrane stabilization. SOD1-G93A transgenic ALS mice were fed a ketogenic diet (KD) based on known formulations for humans. Motor performance, longevity, and motor neuron counts were measured in treated and disease controls. Because mitochondrial dysfunction plays a central role in neuronal cell death in ALS, we also studied the effect that the principal ketone body, D-beta-3 hydroxybutyrate (DBH), has on mitochondrial ATP generation and neuroprotection. Blood ketones were > 3.5 times higher in KD fed animals compared to controls. KD fed mice lost 50% of baseline motor performance 25 days later than disease controls. KD animals weighed 4.6 g more than disease control animals at study endpoint; the interaction between diet and change in weight was significant (p = 0.047). In spinal cord sections obtained at the study endpoint, there were more motor neurons in KD fed animals (p = 0.030). DBH prevented rotenone mediated inhibition of mitochondrial complex I but not malonate inhibition of complex II. Rotenone neurotoxicity in SMI-32 immunopositive motor neurons was also inhibited by DBH. This is the first study showing that diet, specifically a KD, alters the progression of the clinical and biological manifestations of the G93A SOD1 transgenic mouse model of ALS. These effects may be due to the ability of ketone bodies to promote ATP synthesis and bypass inhibition of complex I in the mitochondrial respiratory chain.

The Effect of tDCS on Cognition and Neurologic Recovery of Rats with Alzheimer's Disease.

PubMed

Yu, Seong Hun; Park, Seong Doo; Sim, Ki Chel

2014-02-01

[Purpose] This study examined the effect of the application of transcranial direct current stimulation (tDCS) on neurologic recovery and cognitive function of rats with Alzheimer-like dementia induced by scopolamine injections. [Subjects] To create a cognition dysfunction model, intraperitoneal injection of scopolamine was given to Sprague-Dawley rats that subsequently received tDCS for 4 weeks. [Methods] Changes in motor behavior were evaluated by conducting an open field test. Acetylcholine content in the cerebral cortex and hippocampus was examined for a biochemical assessment. [Results] With respect to changes in motor behavior, group II showed the most meaningful difference after scopolamine injection, followed by group III. In the biochemical assessment, the results of the examination of acetylcholine content in the tissue of the cerebral cortex and the hippocampus on the 14th and 28th days, respectively, showed the most significant increase in group II, followed by group III. [Conclusion] The above findings confirm that tDCS application after the onset of cognitive dysfunction caused by Alzheimer's disease leads to a positive effect on motor behavior and biochemical changes, and this effect is maintained over a specific period of time.

Gastrointestinal Dysfunctions in Parkinson's Disease: Symptoms and Treatments

PubMed Central

Aubé, Benoit; Côté, Mélissa; Morin, Nicolas; Di Paolo, Thérèse

2016-01-01

A diagnosis of Parkinson's disease is classically established after the manifestation of motor symptoms such as rigidity, bradykinesia, and tremor. However, a growing body of evidence supports the hypothesis that nonmotor symptoms, especially gastrointestinal dysfunctions, could be considered as early biomarkers since they are ubiquitously found among confirmed patients and occur much earlier than their motor manifestations. According to Braak's hypothesis, the disease is postulated to originate in the intestine and then spread to the brain via the vagus nerve, a phenomenon that would involve other neuronal types than the well-established dopaminergic population. It has therefore been proposed that peripheral nondopaminergic impairments might precede the alteration of dopaminergic neurons in the central nervous system and, ultimately, the emergence of motor symptoms. Considering the growing interest in the gut-brain axis in Parkinson's disease, this review aims at providing a comprehensive picture of the multiple gastrointestinal features of the disease, along with the therapeutic approaches used to reduce their burden. Moreover, we highlight the importance of gastrointestinal symptoms with respect to the patients' responses towards medical treatments and discuss the various possible adverse interactions that can potentially occur, which are still poorly understood. PMID:28050310

Relationship between respiratory failure and plasma noradrenaline levels in amyotrophic lateral sclerosis.

PubMed

Yamashita, A; Koike, Y; Takahashi, A; Hirayama, M; Murakami, N; Sobue, G

1997-08-01

We evaluated plasma noradrenaline (NA) levels at test and during head-up tilt test in 20 patients with sporadic amyotrophic lateral sclerosis (ALS). Their fasting plasma NA levels ranged from 195 to 4227 pg/ml. The average plasma NA level was 483 pg/ml in five ambulatory patients, 341 in two wheelchair-bound patients, 1264 in 11 bedridden patients, and 208 in two respirator-dependent patients whose disability grading was the worst among the four groups. Arterial carbon dioxide (PCO2) was evaluated as a measure of respiratory function. The coefficient of correlation between PCO2 and plasma NA was r = 0.654 (p < 0.01). Either respiratory failure or lower motor neuron dysfunction may relate to the elevation of plasma NA levels. In the two bedridden patients, plasma NA levels and heart rate at rest increased significantly as the disease progressed. Cardiovascular responses to head-up tilting were normal. These data suggest that the elevation of plasma NA levels may be related to progression of respiratory failure and lower motor neuron dysfunction. In conclusion, sympathetic hyperactivity in ALS is considered to be not primary, but secondary to somatic motor disabilities and respiratory failure.

Neurological Dysfunction in Early Maturity of a Model for Niemann-Pick C1 Carrier Status.

PubMed

Hung, Ya Hui; Walterfang, Mark; Churilov, Leonid; Bray, Lisa; Jacobson, Laura H; Barnham, Kevin J; Jones, Nigel C; O'Brien, Terence J; Velakoulis, Dennis; Bush, Ashley I

2016-07-01

Autosomal recessive inheritance of NPC1 with loss-of-function mutations underlies Niemann-Pick disease, type C1 (NP-C1), a lysosomal storage disorder with progressive neurodegeneration. It is uncertain from limited biochemical studies and patient case reports whether NPC1 haploinsufficiency can cause a partial NP-C1 phenotype in carriers. In the present study, we examined this possibility in heterozygotes of a natural loss-of-function mutant Npc1 mouse model. We found partial motor dysfunction and increased anxiety-like behavior in Npc1 (+/-) mice by 9 weeks of age. Relative to Npc1 (+/+) mice, Npc1 (+/-) mice failed to show neurodevelopmental improvements in motor coordination and balance on an accelerating Rotarod. In the open-field test, Npc1 (+/-) mice showed an intermediate phenotype in spontaneous locomotor activity compared with Npc1 (+/+) and Npc1 (-/-) mice, as well as decreased center tendency. Together with increased stride length under anxiogenic conditions on the DigiGait treadmill, these findings are consistent with heightened anxiety. Our findings indicate that pathogenic NPC1 allele carriers, who represent about 0.66 % of humans, could be vulnerable to motor and anxiety disorders.

Novel Neuroprotective Multicomponent Therapy for Amyotrophic Lateral Sclerosis Designed by Networked Systems

PubMed Central

Herrando-Grabulosa, Mireia; Mulet, Roger; Pujol, Albert; Mas, José Manuel; Navarro, Xavier; Aloy, Patrick; Coma, Mireia; Casas, Caty

2016-01-01

Amyotrophic Lateral Sclerosis is a fatal, progressive neurodegenerative disease characterized by loss of motor neuron function for which there is no effective treatment. One of the main difficulties in developing new therapies lies on the multiple events that contribute to motor neuron death in amyotrophic lateral sclerosis. Several pathological mechanisms have been identified as underlying events of the disease process, including excitotoxicity, mitochondrial dysfunction, oxidative stress, altered axonal transport, proteasome dysfunction, synaptic deficits, glial cell contribution, and disrupted clearance of misfolded proteins. Our approach in this study was based on a holistic vision of these mechanisms and the use of computational tools to identify polypharmacology for targeting multiple etiopathogenic pathways. By using a repositioning analysis based on systems biology approach (TPMS technology), we identified and validated the neuroprotective potential of two new drug combinations: Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine. In addition, we estimated their molecular mechanisms of action in silico and validated some of these results in a well-established in vitro model of amyotrophic lateral sclerosis based on cultured spinal cord slices. The results verified that Aliretinoin and Pranlukast, and Aliretinoin and Mefloquine promote neuroprotection of motor neurons and reduce microgliosis. PMID:26807587

Early physiological abnormalities after simian immunodeficiency virus infection.

PubMed

Horn, T F; Huitron-Resendiz, S; Weed, M R; Henriksen, S J; Fox, H S

1998-12-08

Central nervous system (CNS) damage and dysfunction are devastating consequences of HIV infection. Although the CNS is one of the initial targets for HIV infection, little is known about early viral-induced abnormalities that can affect CNS function. Here we report the detection of early physiological abnormalities in simian immunodeficiency virus-infected monkeys. The acute infection caused a disruption of the circadian rhythm manifested by rises in body temperature, observed in all five individuals between 1 and 2 weeks postinoculation (p.i.), accompanied by a reduction in daily motor activity to 50% of control levels. Animals remained hyperthermic at 1 and 2 months p.i. and returned to preinoculation temperatures at 3 months after viral inoculation. Although motor activity recovered to baseline values at 1 month p.i., activity levels then decreased to approximately 50% of preinoculation values over the next 2 months. Analysis of sensory-evoked responses 1 month p.i. revealed distinct infection-induced changes in auditory-evoked potential peak latencies that persisted at 3 months after viral inoculation. These early physiological abnormalities may precede the development of observable cognitive or motor deficiencies and can provide an assay to evaluate agents to prevent or alleviate neuronal dysfunction.

Early physiological abnormalities after simian immunodeficiency virus infection

PubMed Central

Horn, Thomas F. W.; Huitron-Resendiz, Salvador; Weed, Michael R.; Henriksen, Steven J.; Fox, Howard S.

1998-01-01

Central nervous system (CNS) damage and dysfunction are devastating consequences of HIV infection. Although the CNS is one of the initial targets for HIV infection, little is known about early viral-induced abnormalities that can affect CNS function. Here we report the detection of early physiological abnormalities in simian immunodeficiency virus-infected monkeys. The acute infection caused a disruption of the circadian rhythm manifested by rises in body temperature, observed in all five individuals between 1 and 2 weeks postinoculation (p.i.), accompanied by a reduction in daily motor activity to 50% of control levels. Animals remained hyperthermic at 1 and 2 months p.i. and returned to preinoculation temperatures at 3 months after viral inoculation. Although motor activity recovered to baseline values at 1 month p.i., activity levels then decreased to approximately 50% of preinoculation values over the next 2 months. Analysis of sensory-evoked responses 1 month p.i. revealed distinct infection-induced changes in auditory-evoked potential peak latencies that persisted at 3 months after viral inoculation. These early physiological abnormalities may precede the development of observable cognitive or motor deficiencies and can provide an assay to evaluate agents to prevent or alleviate neuronal dysfunction. PMID:9844017

Orderly recruitment of motor units under optical control in vivo.

PubMed

Llewellyn, Michael E; Thompson, Kimberly R; Deisseroth, Karl; Delp, Scott L

2010-10-01

A drawback of electrical stimulation for muscle control is that large, fatigable motor units are preferentially recruited before smaller motor units by the lowest-intensity electrical cuff stimulation. This phenomenon limits therapeutic applications because it is precisely the opposite of the normal physiological (orderly) recruitment pattern; therefore, a mechanism to achieve orderly recruitment has been a long-sought goal in physiology, medicine and engineering. Here we demonstrate a technology for reliable orderly recruitment in vivo. We find that under optical control with microbial opsins, recruitment of motor units proceeds in the physiological recruitment sequence, as indicated by multiple independent measures of motor unit recruitment including conduction latency, contraction and relaxation times, stimulation threshold and fatigue. As a result, we observed enhanced performance and reduced fatigue in vivo. These findings point to an unanticipated new modality of neural control with broad implications for nervous system and neuromuscular physiology, disease research and therapeutic innovation.

Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve

PubMed Central

Dean, Jesse C.; Clair-Auger, Joanna M.; Lagerquist, Olle; Collins, David F.

2014-01-01

Motoneurons receive a barrage of inputs from descending and reflex pathways. Much of our understanding about how these inputs are transformed into motor output in humans has come from recordings of single motor units during voluntary contractions. This approach, however, is limited because the input is ill-defined. Herein, we quantify the discharge of soleus motor units in response to well-defined trains of afferent input delivered at physiologically-relevant frequencies. Constant frequency stimulation of the tibial nerve (10–100 Hz for 30 s), below threshold for eliciting M-waves or H-reflexes with a single pulse, recruited motor units in 7/9 subjects. All 25 motor units recruited during stimulation were also recruited during weak (<10% MVC) voluntary contractions. Higher frequencies recruited more units (n = 3/25 at 10 Hz; n = 25/25 at 100 Hz) at shorter latencies (19.4 ± 9.4 s at 10 Hz; 4.1 ± 4.0 s at 100 Hz) than lower frequencies. When a second unit was recruited, the discharge of the already active unit did not change, suggesting that recruitment was not due to increased synaptic drive. After recruitment, mean discharge rate during stimulation at 20 Hz (7.8 Hz) was lower than during 30 Hz (8.6 Hz) and 40 Hz (8.4 Hz) stimulation. Discharge was largely asynchronous from the stimulus pulses with “time-locked” discharge occurring at an H-reflex latency with only a 24% probability. Motor units continued to discharge after cessation of the stimulation in 89% of trials, although at a lower rate (5.8 Hz) than during the stimulation (7.9 Hz). This work supports the idea that the afferent volley evoked by repetitive stimulation recruits motor units through the integration of synaptic drive and intrinsic properties of motoneurons, resulting in “physiological” recruitment which adheres to Henneman’s size principle and results in relatively low discharge rates and asynchronous firing. PMID:25566025

Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve.

PubMed

Dean, Jesse C; Clair-Auger, Joanna M; Lagerquist, Olle; Collins, David F

2014-01-01

Motoneurons receive a barrage of inputs from descending and reflex pathways. Much of our understanding about how these inputs are transformed into motor output in humans has come from recordings of single motor units during voluntary contractions. This approach, however, is limited because the input is ill-defined. Herein, we quantify the discharge of soleus motor units in response to well-defined trains of afferent input delivered at physiologically-relevant frequencies. Constant frequency stimulation of the tibial nerve (10-100 Hz for 30 s), below threshold for eliciting M-waves or H-reflexes with a single pulse, recruited motor units in 7/9 subjects. All 25 motor units recruited during stimulation were also recruited during weak (<10% MVC) voluntary contractions. Higher frequencies recruited more units (n = 3/25 at 10 Hz; n = 25/25 at 100 Hz) at shorter latencies (19.4 ± 9.4 s at 10 Hz; 4.1 ± 4.0 s at 100 Hz) than lower frequencies. When a second unit was recruited, the discharge of the already active unit did not change, suggesting that recruitment was not due to increased synaptic drive. After recruitment, mean discharge rate during stimulation at 20 Hz (7.8 Hz) was lower than during 30 Hz (8.6 Hz) and 40 Hz (8.4 Hz) stimulation. Discharge was largely asynchronous from the stimulus pulses with "time-locked" discharge occurring at an H-reflex latency with only a 24% probability. Motor units continued to discharge after cessation of the stimulation in 89% of trials, although at a lower rate (5.8 Hz) than during the stimulation (7.9 Hz). This work supports the idea that the afferent volley evoked by repetitive stimulation recruits motor units through the integration of synaptic drive and intrinsic properties of motoneurons, resulting in "physiological" recruitment which adheres to Henneman's size principle and results in relatively low discharge rates and asynchronous firing.

Effect of surface sensory and motor electrical stimulation on chronic poststroke oropharyngeal dysfunction.

PubMed

Rofes, L; Arreola, V; López, I; Martin, A; Sebastián, M; Ciurana, A; Clavé, P

2013-11-01

Chronic poststroke oropharyngeal dysfunction (OD) is a common condition, leading to severe complications, including death. Treatments for chronic poststroke OD are scarce. The aim of our study was to assess and compare the efficacy and safety of treatment with surface electrical stimulation (e-stim) at sensory and motor intensities in patients with chronic poststroke OD. Twenty chronic poststroke patients with OD were randomly assigned to (i) sensory e-stim (treatment intensity: 75% of motor threshold) or (ii) motor e-stim (treatment intensity: motor threshold). Patients were treated during 10 days, 1 h/day. Videofluoroscopy was performed at the beginning and end of the study to assess signs of impaired efficacy and safety of swallow and timing of swallow response. Patients presented advanced age (74.95 ± 2.18), 75% were men. The mean days poststroke was 336.26 ± 89.6. After sensory stimulation, the number of unsafe swallows was reduced by 66.7% (p < 0.001), the laryngeal vestibule closure time by 22.94% (p = 0.027) and maximal vertical hyoid extension time by 18.6% (p = 0.036). After motor stimulation, the number of unsafe swallows was reduced by 62.5% (p = 0.002), the laryngeal vestibule closure time by 38.26% (p = 0.009) and maximal vertical hyoid extension time by 24.8% (p = 0.008). Moreover, the motor stimulus reduced the pharyngeal residue by 66.7% (p = 0.002), the upper esophageal sphincter opening time by 39.39% (p = 0.009), and increased bolus propulsion force by 211.1% (p = 0.008). No serious adverse events were detected during the treatment. Surface e-stim is a safe and effective treatment for chronic poststroke dysphagic patients. © 2013 John Wiley & Sons Ltd.

Dysregulation of chromatin remodelling complexes in amyotrophic lateral sclerosis.

PubMed

Tibshirani, Michael; Zhao, Beibei; Gentil, Benoit J; Minotti, Sandra; Marques, Christine; Keith, Julia; Rogaeva, Ekaterina; Zinman, Lorne; Rouaux, Caroline; Robertson, Janice; Durham, Heather D

2017-11-01

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease with paralysis resulting from dysfunction and loss of motor neurons. A common neuropathological finding is attrition of motor neuron dendrites, which make central connections vital to motor control. The chromatin remodelling complex, neuronal Brahma-related gene 1 (Brg1)-associated factor complex (nBAF), is critical for neuronal differentiation, dendritic extension and synaptic function. We have identified loss of the crucial nBAF subunits Brg1, Brg1-associated factor 53b and calcium responsive transactivator in cultured motor neurons expressing FUS or TAR-DNA Binding Protein 43 (TDP-43) mutants linked to familial ALS. When plasmids encoding wild-type or mutant human FUS or TDP-43 were expressed in motor neurons of dissociated spinal cord cultures prepared from E13 mice, mutant proteins in particular accumulated in the cytoplasm. Immunolabelling of nBAF subunits was reduced in proportion to loss of nuclear FUS or TDP-43 and depletion of Brg1 was associated with nuclear retention of Brg1 mRNA. Dendritic attrition (loss of intermediate and terminal dendritic branches) occurred in motor neurons expressing mutant, but not wild-type, FUS or TDP-43. This attrition was delayed by ectopic over-expression of Brg1 and was reproduced by inhibiting Brg1 activity either through genetic manipulation or treatment with the chemical inhibitor, (E)-1-(2-Hydroxyphenyl)-3-((1R, 4R)-5-(pyridin-2-yl)-2, 5-diazabicyclo[2.2.1]heptan-2-yl)prop-2-en-1-one, demonstrating the importance of Brg1 to maintenance of dendritic architecture. Loss of nBAF subunits was also documented in spinal motor neurons in autopsy tissue from familial amyotrophic sclerosis (chromosome 9 open reading frame 72 with G4C2 nucleotide expansion) and from sporadic cases with no identified mutation, pointing to dysfunction of nBAF chromatin remodelling in multiple forms of ALS. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Motor dysfunction in NF1: Mediated by attention deficit or inherent to the disorder?

PubMed

Haas-Lude, Karin; Heimgärtner, Magdalena; Winter, Sarah; Mautner, Victor-Felix; Krägeloh-Mann, Ingeborg; Lidzba, Karen

2018-01-01

Attention deficit and compromised motor skills are both prevalent in Neurofibromatosis type 1 (NF1), but the relationship is unclear. We investigated motor function in children with NF1 and in children with Attention Deficit/Hyperactivity Disorder (ADHD), and explored if, in patients with NF1, attention deficit influences motor performance. Motor performance was measured using the Movement Assessment Battery for Children (M-ABC) in 71 children (26 with NF1 plus ADHD, 14 with NF1 without ADHD, and 31 with ADHD without NF1) aged 6-12 years. There was a significant effect of group on motor performance. Both NF1 groups scored below children with ADHD without NF1. Attention performance mediated motor performance in children with ADHD without NF1, but not in children with NF1. Motor function is not mediated by attention performance in children with NF1. While in ADHD, attention deficit influences motor performance, motor problems in NF1 seem to be independent from attention deficit. This argues for different pathomechanisms in these two groups of developmental disorders. Copyright © 2017 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

Association Between Vestibular Vertigo and Motor Vehicle Accidents: Data From the 2016 National Health Interview Survey.

PubMed

Wei, Eric X; Agrawal, Yuri

2018-05-18

Recent evidence has shown that individuals with vestibular impairment have higher rates of self-reported driving difficulty compared with individuals without vestibular impairment. However, it is unknown whether individuals with vestibular impairment are more likely to be involved in motor vehicle accidents. We used data from the 2016 National Health Interview Survey of U.S. adults to evaluate whether individuals with vestibular vertigo are more likely to experience motor vehicle accidents relative to individuals without vestibular vertigo. In multivariate analysis, vestibular vertigo was associated with an over threefold increased odds of motor vehicle accidents (odds ratio, 3.5; 95% confidence interval, 1.7-7.3). This study supports an assciation between vestibular dysfunction and driving impairment, and provides a relative risk of motor vehicle accidents associated with vestibular vertigo that clinicians may utilize in counseling patients on the potential safety hazards of driving.

Olfaction in Parkinson's disease and related disorders

PubMed Central

Doty, Richard L.

2012-01-01

Olfactory dysfunction is an early ‘pre-clinical’ sign of Parkinson's disease (PD). The present review is a comprehensive and up-to-date assessment of such dysfunction in PD and related disorders. The olfactory bulb is implicated in the dysfunction, since only those syndromes with olfactory bulb pathology exhibit significant smell loss. The role of dopamine in the production of olfactory system pathology is enigmatic, as overexpression of dopaminergic cells within the bulb's glomerular layer is a common feature of PD and most animal models of PD. Damage to cholinergic, serotonergic, and noradrenergic systems is likely involved, since such damage is most marked in those diseases with the most smell loss. When compromised, these systems, which regulate microglial activity, can influence the induction of localized brain inflammation, oxidative damage, and cytosolic disruption of cellular processes. In monogenetic forms of PD, olfactory dysfunction is rarely observed in asymptomatic gene carriers, but is present in many of those that exhibit the motor phenotype. This suggests that such gene-related influences on olfaction, when present, take time to develop and depend upon additional factors, such as those from aging, other genes, formation of α-synuclein- and tau-related pathology,or lowered thresholds to oxidative stress from toxic insults. The limited data available suggest that the physiological determinants of the early changes in PD-related olfactory function are likely multifactorial and may include the same determinants as those responsible for a number of other non-motor symptoms of PD, such as dysautonomia and sleep disturbances. PMID:22192366

Lutein protects dopaminergic neurons against MPTP-induced apoptotic death and motor dysfunction by ameliorating mitochondrial disruption and oxidative stress.

PubMed

Nataraj, Jagatheesan; Manivasagam, Thamilarasan; Thenmozhi, Arokiasamy Justin; Essa, Musthafa Mohammed

2016-07-01

Mitochondrial dysfunction and oxidative stress-mediated apoptosis plays an important role in various neurodegenerative diseases including Huntington's disease, Parkinson's disease (PD) and Alzheimer's disease (AD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), the most widely used neurotoxin mimics the symptoms of PD by inhibiting mitochondrial complex I that stimulates excessive intracellular reactive oxygen species (ROS) and finally leads to mitochondrial-dependent apoptosis. Lutein, a carotenoid of xanthophyll family, is found abundantly in leafy green vegetables such as spinach, kale and in egg yolk, animal fat and human eye retinal macula. Increasing evidence indicates that lutein has offers benefits against neuronal damages during diabetic retinopathy, ischemia and AD by virtue of its mitochondrial protective, antioxidant and anti-apoptotic properties. Male C57BL/6 mice (23-26 g) were randomized and grouped in to Control, MPTP, and Lutein treated groups. Lutein significantly reversed the loss of nigral dopaminergic neurons by increasing the striatal dopamine level in mice. Moreover, lutein-ameliorated MPTP induced mitochondrial dysfunction, oxidative stress and motor abnormalities. In addition, lutein repressed the MPTP-induced neuronal damage/apoptosis by inhibiting the activation of pro-apoptotic markers (Bax, caspases-3, 8 and 9) and enhancing anti-apoptotic marker (Bcl-2) expressions. Our current results revealed that lutein possessed protection on dopaminergic neurons by enhancing antioxidant defense and diminishing mitochondrial dysfunction and apoptotic death, suggesting the potential benefits of lutein for PD treatment.

Nonmotor symptoms in patients with Parkinson disease

PubMed Central

Zhang, Tie-mei; Yu, Shu-yang; Guo, Peng; Du, Yang; Hu, Yang; Piao, Ying-shan; Zuo, Li-jun; Lian, Teng-hong; Wang, Rui-dan; Yu, Qiu-jin; Jin, Zhao; Zhang, Wei

2016-01-01

Abstract Parkinson disease (PD) is usually accompanied by numerous nonmotor symptoms (NMS), such as neuropsychiatric symptoms, sleep disorders, autonomic dysfunctions, and sensory disturbances. However, it is not clear that the factors influencing the occurrence of NMS and its sequence with motor symptoms (MS). We conducted comprehensive assessments of NMS by using 13 scales in 1119 PD patients. A total of 70.8% PD patients present NMS. Olfactory dysfunction tends to occur in PD patients with older age, more severe depression, sleep problems, and autonomic dysfunctions. Older patients are more likely to have olfactory dysfunction before MS than younger patients. Rapid eye movement behavior disorder is more prone to happen in patients with older age, older onset age, more severe depression, sleep problems, and autonomic dysfunctions. Patients with rapid eye movement behavior disorder before MS are older in onset age than after group. Olfactory dysfunction, constipation, rapid eye movement behavior disorder, and depression, as early warning NMSs of PD, connected to each other. There is a clinical heterogeneity that older patients are more likely to have NMS before MS, while younger patients are opposite. PMID:27977578

Insulin resistance is associated with cognition among HIV-1-infected patients: the Hawaii Aging With HIV cohort.

PubMed

Valcour, Victor G; Sacktor, Ned C; Paul, Robert H; Watters, Michael R; Selnes, Ola A; Shiramizu, Bruce T; Williams, Andrew E; Shikuma, Cecilia M

2006-12-01

To determine if insulin resistance (IR) is associated with lower cognitive performance among HIV-1-infected adults and to determine if advanced age magnifies risk. Cross-sectional analysis within the Hawaii Aging With HIV Cohort. We calculated the homeostasis model assessment of insulin resistance (HOMA-IR) among 145 cohort participants. Values were compared to concurrent neuropsychological test performance and cognitive diagnoses. Hypertension, body mass index (BMI), and non-Caucasian self-identity were directly related to insulin resistance (IR); however, age, CD4 lymphocyte count, and rates of treatment with HAART were not. In logistic regression analyses and stratifying cognition status on a 3-tiered scale (normal, minor cognitive motor disorder (MCMD), and HIV-associated dementia (HAD)), we identified an increased risk of meeting a higher diagnostic category as HOMA-IR increased (OR, 1.12; 95% CI: 1.003 to 1.242 per unit of HOMA-IR, P = 0.044). In linear regression models and among nondiabetic participants, an increasing degree of IR was associated with lower performance on neuropsychological summary scores. IR is associated with cognitive dysfunction in this contemporary HIV-1 cohort enriched with older individuals. Metabolic dysfunction may contribute to the multifactorial pathogenesis of cognitive impairment in the era of HAART.

Common drive to the upper airway muscle genioglossus during inspiratory loading

PubMed Central

Woods, Michael J.; Nicholas, Christian L.; Semmler, John G.; Chan, Julia K. M.; Jordan, Amy S.

2015-01-01

Common drive is thought to constitute a central mechanism by which the efficiency of a motor neuron pool is increased. This study tested the hypothesis that common drive to the upper airway muscle genioglossus (GG) would increase with increased respiratory drive in response to an inspiratory load. Respiration, GG electromyographic (EMG) activity, single-motor unit activity, and coherence in the 0–5 Hz range between pairs of GG motor units were assessed for the 30 s before an inspiratory load, the first and second 30 s of the load, and the 30 s after the load. Twelve of twenty young, healthy male subjects provided usable data, yielding 77 pairs of motor units: 2 Inspiratory Phasic, 39 Inspiratory Tonic, 15 Expiratory Tonic, and 21 Tonic. Respiratory and GG inspiratory activity significantly increased during the loads and returned to preload levels during the postload periods (all showed significant quadratic functions over load trials, P < 0.05). As hypothesized, common drive increased during the load in inspiratory modulated motor units to a greater extent than in expiratory/tonic motor units (significant load × discharge pattern interaction, P < 0.05). Furthermore, this effect persisted during the postload period. In conclusion, common drive to inspiratory modulated motor units was elevated in response to increased respiratory drive. The postload elevation in common drive was suggestive of a poststimulus activation effect. PMID:26378207

Estimates of Commercial Motor Vehicles Using the Southwest Border Crossings

DOT National Transportation Integrated Search

2000-09-20

The United States has experienced almost a five-fold increase in commercial motor vehicle traffic to and from Mexico during the past sixteen years. There were more than 4< million commercial motor vehicle (CMV) crossings from Mexico into the United S...

Effects of aging and Parkinson's disease on motor unit remodeling: influence of resistance exercise training.

PubMed

Kelly, Neil A; Hammond, Kelley G; Bickel, C Scott; Windham, Samuel T; Tuggle, S Craig; Bamman, Marcas M

2018-04-01

Aging muscle atrophy is in part a neurodegenerative process revealed by denervation/reinnervation events leading to motor unit remodeling (i.e., myofiber type grouping). However, this process and its physiological relevance are poorly understood, as is the wide-ranging heterogeneity among aging humans. Here, we attempted to address 1) the relation between myofiber type grouping and molecular regulators of neuromuscular junction (NMJ) stability; 2) the impact of motor unit remodeling on recruitment during submaximal contractions; 3) the prevalence and impact of motor unit remodeling in Parkinson's disease (PD), an age-related neurodegenerative disease; and 4) the influence of resistance exercise training (RT) on regulators of motor unit remodeling. We compared type I myofiber grouping, molecular regulators of NMJ stability, and the relative motor unit activation (MUA) requirement during a submaximal sit-to-stand task among untrained but otherwise healthy young (YA; 26 yr, n = 27) and older (OA; 66 yr, n = 91) adults and OA with PD (PD; 67 yr, n = 19). We tested the effects of RT on these outcomes in OA and PD. PD displayed more motor unit remodeling, alterations in NMJ stability regulation, and a higher relative MUA requirement than OA, suggesting PD-specific effects. The molecular and physiological outcomes tracked with the severity of type I myofiber grouping. Together these findings suggest that age-related motor unit remodeling, manifested by type I myofiber grouping, 1) reduces MUA efficiency to meet submaximal contraction demand, 2) is associated with disruptions in NMJ stability, 3) is further impacted by PD, and 4) may be improved by RT in severe cases. NEW & NOTEWORTHY Because the physiological consequences of varying amounts of myofiber type grouping are unknown, the current study aims to characterize the molecular and physiological correlates of motor unit remodeling. Furthermore, because exercise training has demonstrated neuromuscular benefits in aged humans and improved innervation status and neuromuscular junction integrity in animals, we provide an exploratory analysis of the effects of high-intensity resistance training on markers of neuromuscular degeneration in both Parkinson's disease (PD) and age-matched older adults.

Hip position and sex differences in motor unit firing patterns of the vastus medialis and vastus medialis oblique in healthy individuals.

PubMed

Peng, Yi-Ling; Tenan, Matthew S; Griffin, Lisa

2018-06-01

Weakness of the vastus medialis oblique (VMO) has been proposed to explain the high prevalence of knee pain in female subjects. Clinicians commonly use exercises in an attempt to preferentially activate the VMO. Recently, our group found evidence to support clinical theory that the VMO is neurologically distinct from the vastus medialis (VM). However, the ability to voluntarily activate these muscle subsections is still disputed. The aim of this study was to determine if VM and VMO activation varies between sexes and if control of the two muscles is different between rehabilitation exercises. Thirteen men and 13 women performed isometric straight leg raises in two hip positions, neutral hip rotation and 30 degrees lateral hip rotation. Bipolar intramuscular fine-wire electrodes were inserted into the VM and VMO to obtain motor unit recruitment thresholds and initial firing rates at recruitment. Linear mixed models and Tukey post hoc tests were used to assess significant differences in 654 motor units. Women demonstrated faster motor unit firing rate at recruitment, 1.18 ± 0.56 Hz higher than men. Motor units fired 0.47 ± 0.19 Hz faster during neutral hip rotation compared with lateral hip rotation. The VMO motor units were recruited 2.92 ± 1.28% earlier than the VM. All motor units were recruited 3.74 ± 1.27% earlier during neutral hip rotation than lateral hip rotation. Thus the VM and the VMO can be activated differentially, and their motor unit recruitment properties are affected by sex and hip position. NEW & NOTEWORTHY This is the first study to reveal differential activation of the vastus medialis oblique from the vastus medialis in clinical exercise protocols. Our research group used fine-wire electrodes to examine EMG signals of the vastus medialis oblique and vastus medialis to avoid possible cross talk. We also consider the effect of sex on motor unit firing patterns because of higher prevalence of knee pain in women, and yet few studies evaluating the sex differences in neuromuscular control.

Long-term neurodevelopmental outcome and exercise capacity after corrective surgery for tetralogy of Fallot or ventricular septal defect in infancy.

PubMed

Hövels-Gürich, Hedwig H; Konrad, Kerstin; Skorzenski, Daniela; Nacken, Claudia; Minkenberg, Ralf; Messmer, Bruno J; Seghaye, Marie-Christine

2006-03-01

The purpose of this prospective study was to assess whether neurodevelopmental status and exercise capacity of children 5 to 10 years after corrective surgery for tetralogy of Fallot or ventricular septal defect in infancy was different compared with normal children and influenced by the preoperative condition of hypoxemia or cardiac insufficiency. Forty unselected children, 20 with tetralogy of Fallot and hypoxemia and 20 with ventricular septal defect and cardiac insufficiency, operated on with combined deep hypothermic circulatory arrest and low flow cardiopulmonary bypass at a mean age of 0.7 +/- 0.3 years (mean +/- SD), underwent, at mean age 7.4 +/- 1.6 years, standardized evaluation of neurologic status, gross motor function, intelligence, academic achievement, language, and exercise capacity. Results were compared between the groups and related to preoperative, perioperative, and postoperative status and management. Rate of mild neurologic dysfunction was increased compared with normal children, but not different between the groups. Exercise capacity and socioeconomic status were not different compared with normal children and between the groups. Compared with the normal population, motor function, formal intelligence, academic achievement, and expressive and receptive language were significantly reduced (p < 0.01 to p < 0.001) in the whole group and in the subgroups, except for normal intelligence in ventricular septal defect patients. Motor dysfunction was significantly higher in the Fallot group compared with the ventricular septal defect group (p < 0.01) and correlated with neurologic dysfunction, lower intelligence, and reduced expressive language (p < 0.05 each). Reduced New York Heart Association functional class was correlated with lower exercise capacity and longer duration of cardiopulmonary bypass (p < 0.05 each). Reduced socioeconomic status significantly influenced dysfunction in formal intelligence (p < 0.01) and academic achievement (p < 0.05). Preoperative risk factors such as prenatal hypoxia, perinatal asphyxia, and preterm birth, factors of perioperative management such as cardiac arrest, lowest nasopharyngeal temperature, and age at surgery, and postoperative risk factors as postoperative cardiocirculatory insufficiency and duration of mechanical ventilation were not different between the groups and had no influence on outcome. Degree of hypoxemia in Fallot patients and degree of cardiac insufficiency in ventricular septal defect patients did not influence the outcome within the subgroups. Children with preoperative hypoxemia in infancy are at higher risk for motor dysfunction than children with cardiac insufficiency. Corrective surgery in infancy for tetralogy of Fallot or ventricular septal defect with combined circulatory arrest and low flow bypass is associated with reduced neurodevelopmental outcome, but not with reduced exercise capacity in childhood. In our experience, the general risk of long-term neurodevelopmental impairment is related to unfavorable effects of the global perioperative management. Socioeconomic status influences cognitive capabilities.

Detail, unit 4, 3,000 hp synchronous pump motor. Manufactured by ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail, unit 4, 3,000 hp synchronous pump motor. Manufactured by The Electric Products Company, Cleveland, Ohio. Unit 5 is identical to this unit - Wellton-Mohawk Irrigation System, Pumping Plant No. 2, Bounded by Interstate 8 to south, Wellton, Yuma County, AZ

[Minimal emotional dysfunction and first impression formation in personality disorders].

PubMed

Linden, M; Vilain, M

2011-01-01

"Minimal cerebral dysfunctions" are isolated impairments of basic mental functions, which are elements of complex functions like speech. The best described are cognitive dysfunctions such as reading and writing problems, dyscalculia, attention deficits, but also motor dysfunctions such as problems with articulation, hyperactivity or impulsivity. Personality disorders can be characterized by isolated emotional dysfunctions in relation to emotional adequacy, intensity and responsivity. For example, paranoid personality disorders can be characterized by continuous and inadequate distrust, as a disorder of emotional adequacy. Schizoid personality disorders can be characterized by low expressive emotionality, as a disorder of effect intensity, or dissocial personality disorders can be characterized by emotional non-responsivity. Minimal emotional dysfunctions cause interactional misunderstandings because of the psychology of "first impression formation". Studies have shown that in 100 ms persons build up complex and lasting emotional judgements about other persons. Therefore, minimal emotional dysfunctions result in interactional problems and adjustment disorders and in corresponding cognitive schemata.From the concept of minimal emotional dysfunctions specific psychotherapeutic interventions in respect to the patient-therapist relationship, the diagnostic process, the clarification of emotions and reality testing, and especially an understanding of personality disorders as impairment and "selection, optimization, and compensation" as a way of coping can be derived.

A software package for interactive motor unit potential classification using fuzzy k-NN classifier.

PubMed

Rasheed, Sarbast; Stashuk, Daniel; Kamel, Mohamed

2008-01-01

We present an interactive software package for implementing the supervised classification task during electromyographic (EMG) signal decomposition process using a fuzzy k-NN classifier and utilizing the MATLAB high-level programming language and its interactive environment. The method employs an assertion-based classification that takes into account a combination of motor unit potential (MUP) shapes and two modes of use of motor unit firing pattern information: the passive and the active modes. The developed package consists of several graphical user interfaces used to detect individual MUP waveforms from a raw EMG signal, extract relevant features, and classify the MUPs into motor unit potential trains (MUPTs) using assertion-based classifiers.

Effect of hindlimb unloading on stereological parameters of the motor cortex and hippocampus in male rats.

PubMed

Salehi, Mohammad Saied; Mirzaii-Dizgah, Iraj; Vasaghi-Gharamaleki, Behnoosh; Zamiri, Mohammad Javad

2016-11-09

Hindlimb unloading (HU) can cause motion and cognition dysfunction, although its cellular and molecular mechanisms are not well understood. The aim of the present study was to determine the stereological parameters of the brain areas involved in motion (motor cortex) and spatial learning - memory (hippocampus) under an HU condition. Sixteen adult male rats, kept under a 12 : 12 h light-dark cycle, were divided into two groups of freely moving (n=8) and HU (n=8) rats. The volume of motor cortex and hippocampus, the numerical cell density of neurons in layers I, II-III, V, and VI of the motor cortex, the entire motor cortex as well as the primary motor cortex, and the numerical density of the CA1, CA3, and dentate gyrus subregions of the hippocampus were estimated. No significant differences were observed in the evaluated parameters. Our results thus indicated that motor cortical and hippocampal atrophy and cell loss may not necessarily be involved in the motion and spatial learning memory impairment in the rat.

Firing patterns of spontaneously active motor units in spinal cord-injured subjects.

PubMed

Zijdewind, Inge; Thomas, Christine K

2012-04-01

Involuntary motor unit activity at low rates is common in hand muscles paralysed by spinal cord injury. Our aim was to describe these patterns of motor unit behaviour in relation to motoneurone and motor unit properties. Intramuscular electromyographic activity (EMG), surface EMG and force were recorded for 30 min from thenar muscles of nine men with chronic cervical SCI. Motor units fired for sustained periods (>10 min) at regular (coefficient of variation ≤ 0.15, CV, n =19 units) or irregular intervals (CV>0.15, n =14). Regularly firing units started and stopped firing independently suggesting that intrinsic motoneurone properties were important for recruitment and derecruitment. Recruitment (3.6 Hz, SD 1.2), maximal (10.2 Hz, SD 2.3, range: 7.5-15.4 Hz) and derecruitment frequencies were low (3.3 Hz, SD 1.6), as were firing rate increases after recruitment (~20 intervals in 3 s). Once active, firing often covaried, promoting the idea that units received common inputs.Half of the regularly firing units showed a very slow decline (>40 s) in discharge before derecruitment and had interspike intervals longer than their estimated after hyperpolarisation potential (AHP) duration (estimated by death rate and breakpoint analyses). The other units were derecruited more abruptly and had shorter estimated AHP durations. Overall, regularly firing units had longer estimated AHP durations and were weaker than irregularly firing units, suggesting they were lower threshold units. Sustained firing of units at regular rates may reflect activation of persistent inward currents, visible here in the absence of voluntary drive, whereas irregularly firing units may only respond to synaptic noise.

Energy Homeostasis and Abnormal RNA Metabolism in Amyotrophic Lateral Sclerosis

PubMed Central

Liu, Yu-Ju; Tsai, Po-Yi; Chern, Yijuang

2017-01-01

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease that is clinically characterized by progressive muscle weakness and impaired voluntary movement due to the loss of motor neurons in the brain, brain stem and spinal cord. To date, no effective treatment is available. Ample evidence suggests that impaired RNA homeostasis and abnormal energy status are two major pathogenesis pathways in ALS. In the present review article, we focus on recent studies that report molecular insights of both pathways, and discuss the possibility that energy dysfunction might negatively regulate RNA homeostasis via the impairment of cytoplasmic-nuclear shuttling in motor neurons and subsequently contribute to the development of ALS. PMID:28522961

A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle.

PubMed

van Bolhuis, A I; Holsheimer, J; Savelberg, H H

2001-05-30

Electrical stimulation of peripheral nerve results in a motor-unit recruitment order opposite to that attained by natural neural control, i.e. from large, fast-fatiguing to progressively smaller, fatigue-resistant motor-units. Yet animal studies involving physiological exercise protocols of low intensity and long duration require minimal fatigue. The present study sought to apply a nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle. Two pulse generators were used, independently supplying short supramaximal cathodal stimulating pulses (0.5 ms) and long subthreshold cathodal inactivating pulses (1.5 s) to the sciatic nerve. Propagation of action potentials was selectively blocked in nerve fibres of different diameter by adjusting the strength of the inactivating current. A tensile-testing machine was used to gauge isometric muscle force of the plantaris and both heads of the gastrocnemius muscle. The order of motor-unit recruitment was estimated from twitch characteristics, i.e. peak force and relaxation time. The results showed prolonged relaxation at lower twitch peak forces as the intensity of the inactivating current increased, indicating a reduction of the number of large motor-units to force production. It is shown that the nerve stimulation method described is effective in mimicking physiological muscle control.

49 CFR 565.24 - Motor vehicles imported into the United States.

Code of Federal Regulations, 2013 CFR

2013-10-01

... HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IDENTIFICATION NUMBER (VIN) REQUIREMENTS Alternative VIN Requirements In Effect for Limited Period § 565.24 Motor vehicles imported into... 49 Transportation 6 2013-10-01 2013-10-01 false Motor vehicles imported into the United States...

49 CFR 565.24 - Motor vehicles imported into the United States.

Code of Federal Regulations, 2011 CFR

2011-10-01

... HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IDENTIFICATION NUMBER (VIN) REQUIREMENTS Alternative VIN Requirements In Effect for Limited Period § 565.24 Motor vehicles imported into... 49 Transportation 6 2011-10-01 2011-10-01 false Motor vehicles imported into the United States...

49 CFR 565.24 - Motor vehicles imported into the United States.

Code of Federal Regulations, 2014 CFR

2014-10-01

... HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IDENTIFICATION NUMBER (VIN) REQUIREMENTS Alternative VIN Requirements In Effect for Limited Period § 565.24 Motor vehicles imported into... 49 Transportation 6 2014-10-01 2014-10-01 false Motor vehicles imported into the United States...

49 CFR 565.24 - Motor vehicles imported into the United States.

Code of Federal Regulations, 2012 CFR

2012-10-01

... HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IDENTIFICATION NUMBER (VIN) REQUIREMENTS Alternative VIN Requirements In Effect for Limited Period § 565.24 Motor vehicles imported into... 49 Transportation 6 2012-10-01 2012-10-01 false Motor vehicles imported into the United States...

49 CFR 565.24 - Motor vehicles imported into the United States.

Code of Federal Regulations, 2010 CFR

2010-10-01

... HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IDENTIFICATION NUMBER (VIN) REQUIREMENTS Alternative VIN Requirements In Effect for Limited Period § 565.24 Motor vehicles imported into... 49 Transportation 6 2010-10-01 2010-10-01 false Motor vehicles imported into the United States...

Influence of Deep Breathing on Heart Rate Variability in Parkinson's Disease: Co-relation with Severity of Disease and Non-Motor Symptom Scale Score.

PubMed

Bidikar, Mukta Pritam; Jagtap, Gayatri J; Chakor, Rahul T

2014-07-01

Dysautonomia and non-motor symptoms (NMS) in Parkinson's disease (PD) are frequent, disabling and reduce quality of life of patient. There is a paucity of studies on autonomic dysfunction in PD in Indian population. The study aimed to evaluate autonomic dysfunction in PD patients and co-relate the findings with severity of PD and Non-Motor Symptoms Scale (NMSS) score. We evaluated autonomic function in 30 diagnosed patients of PD (age 55-70 years) and 30 healthy age-matched controls by 3 min deep breathing test (DBT). NMSS was used to identify non-motor symptoms and Hoehn and Yahr (HY) Scale to grade severity of PD. The DBT findings were co-related with severity of PD (HY staging) and NMSS score. DBT was found to be abnormal in 40% while it was on borderline in 33.3% of PD patients. There was a statistically significant difference (p<0.01) between patients and control group for the DBT. NMS were reported across all the stages of PD but with variable frequency and severity for individual symptom. A negative co-relation was found between results of deep breathing test and clinical severity of disease and NMSS score. Abnormalities of autonomic function and NMS were integral and present across all the stages of PD patients. Early recognition and treatment of these may decrease morbidity and improve quality of life of PD patients.

Gastrointestinal Disorders in Children with Neurodevelopmental Disabilities

ERIC Educational Resources Information Center

Sullivan, Peter B.

2008-01-01

Children with neurodevelopmental disabilities such as cerebral palsy (CP), spina bifida, or inborn errors of metabolism frequently have associated gastrointestinal problems. These include oral motor dysfunction leading to feeding difficulties, risk of aspiration, prolonged feeding times, and malnutrition with its attendant physical compromise.…

Effects of barbell deadlift training on submaximal motor unit firing rates for the vastus lateralis and rectus femoris.

PubMed

Stock, Matt S; Thompson, Brennan J

2014-01-01

Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units.

Motor unit recruitment patterns 1: responses to changes in locomotor velocity and incline.

PubMed

Hodson-Tole, Emma F; Wakeling, James M

2008-06-01

Mammalian skeletal muscles are composed of a mixture of motor unit types, which contribute a range of mechanical and physiological properties to the muscle. For a muscle to effectively contribute to smooth, co-ordinated movement it must activate an appropriate number and combination of motor units to generate the required force over a suitable time period. Much evidence exists indicating that motor units are activated in an orderly fashion, from the slowest through to the fastest. A growing body of evidence, however, indicates that such a recruitment strategy does not always hold true. Here we investigate how motor unit recruitment patterns were influenced by changes in locomotor velocity and incline. Kinematics data and myoelectric signals were collected from three rat ankle extensor muscles during running on a treadmill at nine velocity and incline combinations. Wavelet and principal component analysis were used to simultaneously decompose the signals into time and frequency space. The relative frequency components of the signals were quantified during 20 time windows of a stride from each locomotor condition. Differences in signal frequency components existed between muscles and locomotor conditions. Faster locomotor velocities led to a relative increase in high frequency components, whereas greater inclines led to a relative increase in the low frequency components. These data were interpreted as representing changes in motor unit recruitment patterns in response to changes in the locomotor demand. Motor units were not always recruited in an orderly manner, indicating that recruitment is a multi-factorial phenomenon that is not yet fully understood.

Load type influences motor unit recruitment in biceps brachii during a sustained contraction.

PubMed

Baudry, Stéphane; Rudroff, Thorsten; Pierpoint, Lauren A; Enoka, Roger M

2009-09-01

Twenty subjects participated in four experiments designed to compare time to task failure and motor-unit recruitment threshold during contractions sustained at 15% of maximum as the elbow flexor muscles either supported an inertial load (position task) or exerted an equivalent constant torque against a rigid restraint (force task). Subcutaneous branched bipolar electrodes were used to record single motor unit activity from the biceps brachii muscle during ramp contractions performed before and at 50 and 90% of the time to failure for the position task during both fatiguing contractions. The time to task failure was briefer for the position task than for the force task (P=0.0002). Thirty and 29 motor units were isolated during the force and position tasks, respectively. The recruitment threshold declined by 48 and 30% (P=0.0001) during the position task for motor units with an initial recruitment threshold below and above the target force, respectively, whereas no significant change in recruitment threshold was observed during the force task. Changes in recruitment threshold were associated with a decrease in the mean discharge rate (-16%), an increase in discharge rate variability (+40%), and a prolongation of the first two interspike intervals (+29 and +13%). These data indicate that there were faster changes in motor unit recruitment and rate coding during the position task than the force task despite a similar net muscle torque during both tasks. Moreover, the results suggest that the differential synaptic input observed during the position task influences most of the motor unit pool.

Executive dysfunction predicts social cognition impairment in amyotrophic lateral sclerosis.

PubMed

Watermeyer, Tamlyn J; Brown, Richard G; Sidle, Katie C L; Oliver, David J; Allen, Christopher; Karlsson, Joanna; Ellis, Catherine M; Shaw, Christopher E; Al-Chalabi, Ammar; Goldstein, Laura H

2015-07-01

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder of the motor system with recognised extra-motor and cognitive involvement. This cross-sectional study examined ALS patients' performance on measures requiring social inference, and determined the relationship between such changes and variations in mood, behaviour, personality, empathy and executive function. Fifty-five ALS patients and 49 healthy controls were compared on tasks measuring social cognition and executive function. ALS patients also completed measures examining mood, behaviour and personality. Regression analyses explored the contribution of executive function, mood, behaviour and personality to social cognition scores within the ALS sample. A between-group MANOVA revealed that, the ALS group was impaired relative to controls on two composite scores for social cognition and executive function. Patients also performed worse on individual tests of executive function measuring cognitive flexibility, response inhibition and concept formation, and on individual aspects of social cognition assessing the attribution of emotional and mental states. Regression analyses indicated that ALS-related executive dysfunction was the main predictor of social cognition performance, above and beyond demographic variables, behaviour, mood and personality. On at least some aspects of social cognition, impaired performance in ALS appears to be secondary to executive dysfunction. The profile of cognitive impairment in ALS supports a cognitive continuum between ALS and frontotemporal dementia.

Sacral electrical neuromodulation as an alternative treatment option for lower urinary tract dysfunction.

PubMed

Grünewald, Volker; Höfner, Klaus; Thon, Walter F.; Kuczyk, Markus A.; Jonas, Udo

1999-01-01

Temporary electrical stimulation using anal or vaginal electrodes and an external pulse generator has been a treatment modality for urinary urge incontinence for nearly three decades. In 1981 Tanagho and Schmidt introduced chronic electrical stimulation of the sacral spinal nerves using a permanently implanted sacral foramen electrode and a battery powered pulse generator for treatment of different kinds of lower urinary tract dysfunction, refractory to conservative treatment. At our department chronic unilateral electrical stimulation of the S3 sacral spinal nerve has been used for treatment of vesi-courethral dysfunction in 43 patients with a mean postoperative follow up of 43,6 months. Lasting symptomatic improvement by more than 50 % could be achieved in 13 of 18 patients with motor urge incontinence (72,2 %) and in 18 of the 21 patients with urinary retention (85,7 %). Implants offer a sustained therapeutic effect to treatment responders, which is not achieved by temporary neuromodulation. Chronic neuromodulation should be predominantly considered in patients with urinary retention. Furthermore in patients with motor urge incontinence, refusing temporary techniques or in those requiring too much effort to achieve a sustained clinical effect. Despite high initial costs chronic sacral neuromodulation is an economically reasonable treatment option in the long run, when comparing it to the more invasive remaining therapeutic alternatives.

[Focal cerebral ischemia in rats with estrogen deficiency and endothelial dysfunction].

PubMed

Litvinov, A A; Volotova, E V; Kurkin, D V; Logvinova, E O; Darmanyan, A P; Tyurenkov, I N

2017-01-01

To assess an effect of ovariectomy (OE) on the cerebral blood flow, endothelium-dependent vasodilation, neurological, cognitive and locomotor deficit as markers of brain damage after focal ischemia in rats. The study was conducted in 48 female Wistar rats. Ovariectomy was performed with ovaries and uterine body extirpation, cerebral ischemia was performed by middle cerebral artery occlusion (MCAO) in rats. To assess brain damage, Combs and Garcia scores, 'open field' test (OFT), 'extrapolatory escape test' (EET), 'passive avoidance test' (PAT), 'beam-walking test' were used. Cerebral blood flow was measured using ultrasonic flowmetry. After 7 days of MCAO, the cerebral blood flow in ovarioectomized animals was reduced by 20% compared to sham-ovariectomized animals. Ovariectomized animals with MCAO showed a three-fold endothelium-dependent vasodilation reduction (the reaction of cerebral vessels to the introduction of acetylcholine and N-L-arginine), indicating the presence of severe endothelial dysfunction. In ovarioectomized animals, the cerebral blood flow was reduced by 34% compared to sham-operated animals. MCAO and OE taken together resulted in more than 2-fold increase in neurological, motor disturbances, 3-fold decrease in motor activity of the animals in the OP test. Focal ischemia in ovarioectomized animals with endothelial dysfunction led to memory decrease by 1/5 fold in PAT and by 2-fold in EET.

Radiation-induced cognitive dysfunction and cerebellar oxidative stress in mice: protective effect of alpha-lipoic acid.

PubMed

Manda, Kailash; Ueno, Megumi; Moritake, Takashi; Anzai, Kazunori

2007-02-12

Reactive oxygen species are implicated in neurodegeneration and cognitive disorders due to higher vulnerability of neuronal tissues. The cerebellum is recently reported to be involved in cognitive function. Therefore, present study aimed at investigating the role alpha-lipoic acid against radiation-induced oxidative stress and antioxidant status in cerebellum and its correlation with cognitive dysfunction. We observed spontaneous motor activities and spatial memory task of mice using pyroelectric infrared sensor and programmed video tracking system, respectively. Whole body X-irradiation (6 Gy) of mice substantially impaired the reference memory and motor activities of mice. However, acute intraperitoneal treatment of mice with alpha-lipoic acid prior to irradiation significantly attenuated such cognitive dysfunction. Alpha-lipoic acid pretreatment exerted a very high magnitude of protection against radiation-induced augmentation of protein carbonyls and thiobarbituric acid reactive substance (TBARS) in mice cerebellum. Further, radiation-induced deficit of total, nonprotein and protein-bound sulfhydryl (T-SH, NP-SH, PB-SH) contents of cerebellum and plasma ferric reducing power (FRAP) was also inhibited by alpha-lipoic acid pre-treatment. Moreover, alpha-lipoic acid treated mice showed an intact cytoarchitecture of cerebellum, higher counts of intact Purkinje cells and granular cells in comparison to untreated irradiated mice. Results clearly indicate that alpha-lipoic acid is potent neuroprotective antioxidant.

Neonatal iron supplementation potentiates oxidative stress, energetic dysfunction and neurodegeneration in the R6/2 mouse model of Huntington's disease

PubMed Central

Berggren, Kiersten L.; Chen, Jianfang; Fox, Julia; Miller, Jonathan; Dodds, Lindsay; Dugas, Bryan; Vargas, Liset; Lothian, Amber; McAllum, Erin; Volitakis, Irene; Roberts, Blaine; Bush, Ashley I.; Fox, Jonathan H.

2015-01-01

Huntington’s disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion that encodes a polyglutamine tract in huntingtin (htt) protein. Dysregulation of brain iron homeostasis, oxidative stress and neurodegeneration are consistent features of the HD phenotype. Therefore, environmental factors that exacerbate oxidative stress and iron dysregulation may potentiate HD. Iron supplementation in the human population is common during infant and adult-life stages. In this study, iron supplementation in neonatal HD mice resulted in deterioration of spontaneous motor running activity, elevated levels of brain lactate and oxidized glutathione consistent with increased energetic dysfunction and oxidative stress, and increased striatal and motor cortical neuronal atrophy, collectively demonstrating potentiation of the disease phenotype. Oxidative stress, energetic, and anatomic markers of degeneration were not affected in wild-type littermate iron-supplemented mice. Further, there was no effect of elevated iron intake on disease outcomes in adult HD mice. We have demonstrated an interaction between the mutant huntingtin gene and iron supplementation in neonatal HD mice. Findings indicate that elevated neonatal iron intake potentiates mouse HD and promotes oxidative stress and energetic dysfunction in brain. Neonatal-infant dietary iron intake level may be an environmental modifier of human HD. PMID:25703232

Decreased synaptic plasticity in the medial prefrontal cortex underlies short-term memory deficits in 6-OHDA-lesioned rats.

PubMed

Matheus, Filipe C; Rial, Daniel; Real, Joana I; Lemos, Cristina; Ben, Juliana; Guaita, Gisele O; Pita, Inês R; Sequeira, Ana C; Pereira, Frederico C; Walz, Roger; Takahashi, Reinaldo N; Bertoglio, Leandro J; Da Cunha, Cláudio; Cunha, Rodrigo A; Prediger, Rui D

2016-03-15

Parkinson's disease (PD) is characterized by motor dysfunction associated with dopaminergic degeneration in the dorsolateral striatum (DLS). However, motor symptoms in PD are often preceded by short-term memory deficits, which have been argued to involve deregulation of medial prefrontal cortex (mPFC). We now used a 6-hydroxydopamine (6-OHDA) rat PD model to explore if alterations of synaptic plasticity in DLS and mPFC underlie short-term memory impairments in PD prodrome. The bilateral injection of 6-OHDA (20μg/hemisphere) in the DLS caused a marked loss of dopaminergic neurons in the substantia nigra (>80%) and decreased monoamine levels in the striatum and PFC, accompanied by motor deficits evaluated after 21 days in the open field and accelerated rotarod. A lower dose of 6-OHDA (10μg/hemisphere) only induced a partial degeneration (about 60%) of dopaminergic neurons in the substantia nigra with no gross motor impairments, thus mimicking an early premotor stage of PD. Notably, 6-OHDA (10μg)-lesioned rats displayed decreased monoamine levels in the PFC as well as short-term memory deficits evaluated in the novel object discrimination and in the modified Y-maze tasks; this was accompanied by a selective decrease in the amplitude of long-term potentiation in the mPFC, but not in DLS, without changes of synaptic transmission in either brain regions. These results indicate that the short-term memory dysfunction predating the motor alterations in the 6-OHDA model of PD is associated with selective changes of information processing in PFC circuits, typified by persistent changes of synaptic plasticity. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of physical growth in cerebral palsied children and its possible relationship with gross motor development.

PubMed

Ibrahim, Alaa I; Hawamdeh, Ziad M

2007-03-01

The object of this study was to detect any possible relation between the current gross motor function score for cerebral palsy children and their physical growth parameters. We measured 71 children with spastic cerebral palsy (35 diplegic, 25 quadriplegic and 11 hemiplegic) and a control group of 80 normal children. Measures taken for cerebral palsy and normal children included stature, weight, head circumference and mid upper-arm circumference, and, additionally for the cerebral palsied children, duration of the disease, birth weight, presence or absence of orofacial dysfunction, distribution of paralysis and degree of spasticity. Motor abilities were measured using the Gross Motor Function Measure. Results showed a significant decrease in the stature, current weight, head circumference and mid upper-arm circumference of both sexes of the quadriplegic children, and significant decreases in the current weight of the diplegic girls and the head circumference of the hemiplegic girls. There were also significant decreases in all scores of the quadriplegic children compared to the diplegic and hemiplegic children. Diplegic children had significantly decreased standing, walking and running, and total scores, compared to the hemiplegic children. Total score at age of testing was independently predicted by the duration of the disease, distribution of paralysis, presence or absence of orofacial dysfunction, spasticity index and the current body weight. Our findings indicate that in spastic cerebral palsy the physical growth parameters were markedly decreased in the quadriplegic form compared to other forms. Only current body weight, from the growth parameters, in addition to other relevant clinical data, can be considered predictors of the current gross motor abilities of those children.

Detail, unit 3, 1,100 horsepower (hp) pump motor. Manufactured by ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail, unit 3, 1,100 horsepower (hp) pump motor. Manufactured by the Electric Products Company, Cleveland, Ohio, USA. Units 1,2, and 4 are identical to this unit - Wellton-Mohawk Irrigation System, Pumping Plant No. 1, Bounded by Gila River & Union Pacific Railroad, Wellton, Yuma County, AZ

Repeater F-waves are signs of motor unit pathology in polio survivors.

PubMed

Hachisuka, Akiko; Komori, Tetsuo; Abe, Tatsuya; Hachisuka, Kenji

2015-05-01

The purpose of this study was to determine whether F-waves reveal electrophysiological features of anterior horn cells in polio survivors. Forty-three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F-waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE). A significant increase in abnormally stereotyped ("repeater") F-waves and a reduction of F-wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F-waves had a negative correlation with MUNE. These trends in F-wave persistence and repeater F-waves after motor unit loss are characteristic findings in polio survivors. Repeater F-waves are a sign of motor unit pathology. © 2014 The Authors. Muscle & Nerve Published by Wiley Periodicals, Inc.

Possible role of pannexin 1/P2x7 purinoceptor in neuroprotective mechanism of ischemic postconditioning in mice.

PubMed

Mahi, Namarta; Kumar, Amit; Jaggi, Amteshwar S; Singh, Nirmal; Dhawan, Ravi

2015-06-01

Previous studies have suggested a significant role of pannexin 1 (Panx1)/P2X7 receptor complex in cardioprotective mechanism of ischemic preconditioning and postconditioning (IPC). The present study has been undertaken to investigate whether Panx1/P2X7 purinoceptors are also involved in the neuroprotective mechanism of IPC in mice. Bilateral carotid artery occlusion (BCAO) for 12 min followed by reperfusion for 24 h was used to produce ischemia-reperfusion-induced cerebral injury in Swiss albino mice. For IPC immediately after BCAO of 12 min, three cycles of 10-s ischemia and reperfusion each were given and then prolonged reperfusion of 24 h was used. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using a Morris water maze test. Rotarod test, inclined beam walking test, and neurologic severity score (NSS) were used to assess motor dysfunction. Acetylcholine esterase levels, brain thiobarbituric acid reactive species, and glutathione level were also estimated. BCAO followed by reperfusion produced a significant increase in cerebral infarct size, NSS along with impairment of memory and motor dysfunction. It also increased brain acetylcholine esterase, thiobarbituric acid reactive species levels, and decreased the glutathione level. IPC produced a significant decrease in the cerebral infarct size and NSS along with reversal of ischemia-reperfusion-induced impairment of memory, motor dysfunction, and altered biochemical levels in the brain. IPC-induced neuroprotective effects were significantly abolished by pretreatment of mefloquine (15.0 mg/kg orally; 30.0 mg/kg orally), blocker of Panx1/P2X7 purinoceptor. Therefore, activation of Panx1/P2X7 purinoceptors appears to play a significant role in the neuroprotective mechanism of IPC. Copyright © 2015 Elsevier Inc. All rights reserved.

Pharmacological Modulation of the Mitochondrial Electron Transport Chain in Paclitaxel-Induced Painful Peripheral Neuropathy.

PubMed

Griffiths, Lisa A; Flatters, Sarah J L

2015-10-01

Paclitaxel is an effective first-line chemotherapeutic with the major dose-limiting side effect of painful neuropathy. Mitochondrial dysfunction and oxidative stress have been implicated in paclitaxel-induced painful neuropathy. Here we show the effects of pharmacological modulation of mitochondrial sites that produce reactive oxygen species using systemic rotenone (complex I inhibitor) or antimycin A (complex III inhibitor) on the maintenance and development of paclitaxel-induced mechanical hypersensitivity in adult male Sprague Dawley rats. The maximally tolerated dose (5 mg/kg) of rotenone inhibited established paclitaxel-induced mechanical hypersensitivity. However, some of these inhibitory effects coincided with decreased motor coordination; 3 mg/kg rotenone also significantly attenuated established paclitaxel-induced mechanical hypersensitivity without any motor impairment. The maximally tolerated dose (.6 mg/kg) of antimycin A reversed established paclitaxel-induced mechanical hypersensitivity without any motor impairment. Seven daily doses of systemic rotenone or antimycin A were given either after paclitaxel administration or before and during paclitaxel administration. Rotenone had no significant effect on the development of paclitaxel-induced mechanical hypersensitivity. However, antimycin A significantly inhibited the development of paclitaxel-induced mechanical hypersensitivity when given before and during paclitaxel administration but had no effect when given after paclitaxel administration. These studies provide further evidence of paclitaxel-evoked mitochondrial dysfunction in vivo, suggesting that complex III activity is instrumental in paclitaxel-induced pain. This study provides further in vivo evidence that mitochondrial dysfunction is a key contributor to the development and maintenance of chemotherapy-induced painful neuropathy. This work also indicates that selective modulation of the electron transport chain can induce antinociceptive effects in a preclinical model of paclitaxel-induced pain. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Fluctuations in isometric muscle force can be described by one linear projection of low-frequency components of motor unit discharge rates

PubMed Central

Negro, Francesco; Holobar, Aleš; Farina, Dario

2009-01-01

The aim of the study was to investigate the relation between linear transformations of motor unit discharge rates and muscle force. Intramuscular (wire electrodes) and high-density surface EMG (13 × 5 electrode grid) were recorded from the abductor digiti minimi muscle of eight healthy men during 60 s contractions at 5%, 7.5% and 10% of the maximal force. Spike trains of a total of 222 motor units were identified from the EMG recordings with decomposition algorithms. Principal component analysis of the smoothed motor unit discharge rates indicated that one component (first common component, FCC) described 44.2 ± 7.5% of the total variability of the smoothed discharge rates when computed over the entire contraction interval and 64.3 ± 10.2% of the variability when computed over 5 s intervals. When the FCC was computed from four or more motor units per contraction, it correlated with the force produced by the muscle (62.7 ± 10.1%) by a greater degree (P < 0.001) than the smoothed discharge rates of individual motor units (41.4 ± 7.8%). The correlation between FCC and the force signal increased up to 71.8 ± 13.1% when the duration and the shape of the smoothing window for discharge rates were similar to the average motor unit twitch force. Moreover, the coefficients of variation (CoV) for the force and for the FCC signal were correlated in all subjects (R2 range = 0.14–0.56; P < 0.05) whereas the CoV for force was correlated to the interspike interval variability in only one subject (R2= 0.12; P < 0.05). Similar results were further obtained from measures on the tibialis anterior muscle of an additional eight subjects during contractions at forces up to 20% of the maximal force (e.g. FCC explained 59.8 ± 11.0% of variability of the smoothed discharge rates). In conclusion, one signal captures most of the underlying variability of the low-frequency components of motor unit discharge rates and explains large part of the fluctuations in the motor output during isometric contractions. PMID:19840996

Fluctuations in isometric muscle force can be described by one linear projection of low-frequency components of motor unit discharge rates.

PubMed

Negro, Francesco; Holobar, Ales; Farina, Dario

2009-12-15

The aim of the study was to investigate the relation between linear transformations of motor unit discharge rates and muscle force. Intramuscular (wire electrodes) and high-density surface EMG (13 x 5 electrode grid) were recorded from the abductor digiti minimi muscle of eight healthy men during 60 s contractions at 5%, 7.5% and 10% of the maximal force. Spike trains of a total of 222 motor units were identified from the EMG recordings with decomposition algorithms. Principal component analysis of the smoothed motor unit discharge rates indicated that one component (first common component, FCC) described 44.2 +/- 7.5% of the total variability of the smoothed discharge rates when computed over the entire contraction interval and 64.3 +/- 10.2% of the variability when computed over 5 s intervals. When the FCC was computed from four or more motor units per contraction, it correlated with the force produced by the muscle (62.7 +/- 10.1%) by a greater degree (P < 0.001) than the smoothed discharge rates of individual motor units (41.4 +/- 7.8%). The correlation between FCC and the force signal increased up to 71.8 +/- 13.1% when the duration and the shape of the smoothing window for discharge rates were similar to the average motor unit twitch force. Moreover, the coefficients of variation (CoV) for the force and for the FCC signal were correlated in all subjects (R(2) range = 0.14-0.56; P < 0.05) whereas the CoV for force was correlated to the interspike interval variability in only one subject (R(2) = 0.12; P < 0.05). Similar results were further obtained from measures on the tibialis anterior muscle of an additional eight subjects during contractions at forces up to 20% of the maximal force (e.g. FCC explained 59.8 +/- 11.0% of variability of the smoothed discharge rates). In conclusion, one signal captures most of the underlying variability of the low-frequency components of motor unit discharge rates and explains large part of the fluctuations in the motor output during isometric contractions.

Sensory aspects of movement disorders

PubMed Central

Patel, Neepa; Jankovic, Joseph; Hallett, Mark

2016-01-01

Movement disorders, which include disorders such as Parkinson’s disease, dystonia, Tourette’s syndrome, restless legs syndrome, and akathisia, have traditionally been considered to be disorders of impaired motor control resulting predominantly from dysfunction of the basal ganglia. This notion has been revised largely because of increasing recognition of associated behavioural, psychiatric, autonomic, and other non-motor symptoms. The sensory aspects of movement disorders include intrinsic sensory abnormalities and the effects of external sensory input on the underlying motor abnormality. The basal ganglia, cerebellum, thalamus, and their connections, coupled with altered sensory input, seem to play a key part in abnormal sensorimotor integration. However, more investigation into the phenomenology and physiological basis of sensory abnormalities, and about the role of the basal ganglia, cerebellum, and related structures in somatosensory processing, and its effect on motor control, is needed. PMID:24331796

Innervation zones of fasciculating motor units: observations by a linear electrode array.

PubMed

Jahanmiri-Nezhad, Faezeh; Barkhaus, Paul E; Rymer, William Z; Zhou, Ping

2015-01-01

This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs.

7. UNIT 4, VIEW TO SOUTHEAST, SHOWING GATE MOTOR ASSEMBLY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. UNIT 4, VIEW TO SOUTHEAST, SHOWING GATE MOTOR ASSEMBLY (CENTER), TURBINE (LEFT FOREGROUND), AND GENERATOR (BACKGROUND) - Washington Water Power Company Monroe Street Plant, Units 4 & 5, South Bank Spokane River, below Monroe Street Bridge, Spokane, Spokane County, WA

6. UNIT 5, VIEW TO SOUTHWEST, SHOWING GATE MOTOR ASSEMBLY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. UNIT 5, VIEW TO SOUTHWEST, SHOWING GATE MOTOR ASSEMBLY (CENTER), TURBINE (RIGHT FOREGROUND), AND GENERATOR (BACKGROUND) - Washington Water Power Company Monroe Street Plant, Units 4 & 5, South Bank Spokane River, below Monroe Street Bridge, Spokane, Spokane County, WA

The neurophysiological features of myoclonus-dystonia and differentiation from other dystonias.

PubMed

Popa, Traian; Milani, Paolo; Richard, Aliénor; Hubsch, Cécile; Brochard, Vanessa; Tranchant, Christine; Sadnicka, Anna; Rothwell, John; Vidailhet, Marie; Meunier, Sabine; Roze, Emmanuel

2014-05-01

Myoclonus-dystonia (M-D) is a clinical syndrome characterized by a combination of myoclonic jerks and mild to moderate dystonia. The syndrome is related to ε-sarcoglycan (SGCE) gene mutations in about half the typical cases. Whether the M-D phenotype reflects a primary dysfunction of the cerebellothalamocortical pathway or of the striatopallidothalamocortical pathway is unclear. The exact role of an additional cortical dysfunction in the pathogenesis of M-D is also unknown. To clarify the neurophysiological features of M-D and discuss whether M-D due to SGCE deficiency differs from other primary dystonias. We studied a referred sample of 12 patients with M-D (mean [SD] age, 28.8 [6.2] years; age range, 19-38 years; 5 women) belonging to 11 unrelated families with a proven mutation or deletion of the SGCE gene and a group of 12 age- and sex-matched healthy control individuals. Every participant underwent 3 sessions exploring the excitability of the primary motor cortex, the response of the primary motor cortex to a plasticity-inducing protocol, and the cerebellar-dependent eye-blink classic conditioning (EBCC). The clinical evaluation of patients included the Unified Myoclonus Rating Scale and Burke-Fahn-Marsden Dystonia Rating Scale. Myoclonus-dystonia with a proven SGCE mutation. We measured resting and active motor thresholds, and short-interval intracortical inhibition and facilitation. The plasticity of the motor cortex was evaluated before and for 30 minutes after 600 pulses of rapid paired associative stimulation. The cerebellar functioning was evaluated with the number of conditioned responses during the 6 blocks of EBCC and 1 extinction block. All data were compared between the 2 groups. For patients, correlations were explored between electrophysiological data and clinical scores. We found lower membrane excitability of the corticocortical axons and normal intracortical γ-aminobutyric acid inhibition in contrast with what has been described in other forms of primary dystonia. Myoclonus-dystonia patients also shared some common pathophysiological features of dystonia, including enhanced responsiveness of the motor cortex to plasticity induction and abnormal response to cerebellar conditioning as tested by EBCC. Specific underlying dysfunctions are associated with the very particular clinical phenotype of M-D and make it a unique entity that stands apart from other primary dystonias.

Does a Combination of Virtual Reality, Neuromodulation and Neuroimaging Provide a Comprehensive Platform for Neurorehabilitation? - A Narrative Review of the Literature.

PubMed

Teo, Wei-Peng; Muthalib, Makii; Yamin, Sami; Hendy, Ashlee M; Bramstedt, Kelly; Kotsopoulos, Eleftheria; Perrey, Stephane; Ayaz, Hasan

2016-01-01

In the last decade, virtual reality (VR) training has been used extensively in video games and military training to provide a sense of realism and environmental interaction to its users. More recently, VR training has been explored as a possible adjunct therapy for people with motor and mental health dysfunctions. The concept underlying VR therapy as a treatment for motor and cognitive dysfunction is to improve neuroplasticity of the brain by engaging users in multisensory training. In this review, we discuss the theoretical framework underlying the use of VR as a therapeutic intervention for neurorehabilitation and provide evidence for its use in treating motor and mental disorders such as cerebral palsy, Parkinson's disease, stroke, schizophrenia, anxiety disorders, and other related clinical areas. While this review provides some insights into the efficacy of VR in clinical rehabilitation and its complimentary use with neuroimaging (e.g., fNIRS and EEG) and neuromodulation (e.g., tDCS and rTMS), more research is needed to understand how different clinical conditions are affected by VR therapies (e.g., stimulus presentation, interactivity, control and types of VR). Future studies should consider large, longitudinal randomized controlled trials to determine the true potential of VR therapies in various clinical populations.

An ERP study of vocal emotion processing in asymmetric Parkinson’s disease

PubMed Central

Garrido-Vásquez, Patricia; Pell, Marc D.; Paulmann, Silke; Strecker, Karl; Schwarz, Johannes; Kotz, Sonja A.

2013-01-01

Parkinson’s disease (PD) has been related to impaired processing of emotional speech intonation (emotional prosody). One distinctive feature of idiopathic PD is motor symptom asymmetry, with striatal dysfunction being strongest in the hemisphere contralateral to the most affected body side. It is still unclear whether this asymmetry may affect vocal emotion perception. Here, we tested 22 PD patients (10 with predominantly left-sided [LPD] and 12 with predominantly right-sided motor symptoms) and 22 healthy controls in an event-related potential study. Sentences conveying different emotional intonations were presented in lexical and pseudo-speech versions. Task varied between an explicit and an implicit instruction. Of specific interest was emotional salience detection from prosody, reflected in the P200 component. We predicted that patients with predominantly right-striatal dysfunction (LPD) would exhibit P200 alterations. Our results support this assumption. LPD patients showed enhanced P200 amplitudes, and specific deficits were observed for disgust prosody, explicit anger processing and implicit processing of happy prosody. Lexical speech was predominantly affected while the processing of pseudo-speech was largely intact. P200 amplitude in patients correlated significantly with left motor scores and asymmetry indices. The data suggest that emotional salience detection from prosody is affected by asymmetric neuronal degeneration in PD. PMID:22956665

Does a Combination of Virtual Reality, Neuromodulation and Neuroimaging Provide a Comprehensive Platform for Neurorehabilitation? – A Narrative Review of the Literature

PubMed Central

Teo, Wei-Peng; Muthalib, Makii; Yamin, Sami; Hendy, Ashlee M.; Bramstedt, Kelly; Kotsopoulos, Eleftheria; Perrey, Stephane; Ayaz, Hasan

2016-01-01

In the last decade, virtual reality (VR) training has been used extensively in video games and military training to provide a sense of realism and environmental interaction to its users. More recently, VR training has been explored as a possible adjunct therapy for people with motor and mental health dysfunctions. The concept underlying VR therapy as a treatment for motor and cognitive dysfunction is to improve neuroplasticity of the brain by engaging users in multisensory training. In this review, we discuss the theoretical framework underlying the use of VR as a therapeutic intervention for neurorehabilitation and provide evidence for its use in treating motor and mental disorders such as cerebral palsy, Parkinson’s disease, stroke, schizophrenia, anxiety disorders, and other related clinical areas. While this review provides some insights into the efficacy of VR in clinical rehabilitation and its complimentary use with neuroimaging (e.g., fNIRS and EEG) and neuromodulation (e.g., tDCS and rTMS), more research is needed to understand how different clinical conditions are affected by VR therapies (e.g., stimulus presentation, interactivity, control and types of VR). Future studies should consider large, longitudinal randomized controlled trials to determine the true potential of VR therapies in various clinical populations. PMID:27445739

Peripheral neuromuscular dysfunction and falls in an elderly cohort.

PubMed

Sorock, G S; Labiner, D M

1992-09-01

In a prospective study of 169 tenants of senior citizen housing in New Jersey in 1986-1987, the relations between tests of peripheral sensory and motor functions in the lower extremities and the rate of first falls were evaluated. The mean age of the cohort was 79.8 years. Fifty-seven persons fell at least once during the follow-up period (mean, 5.6 months). After adjustment for history of stroke, heart failure, emphysema, and use of a walker or cane, rate ratios for first falls were elevated in subjects with reduced toe joint position sense (rate ratio (RR) = 2.2) and sharp-dull discrimination (RR = 2.0), but to a lesser extent for reduced ankle strength (RR = 1.5). Presence of one or more of these three deficits was defined as a peripheral neuromuscular dysfunction and was associated with first falls after adjustment for multiple covariates (RR = 2.4, 95% confidence interval 1.3-4.5). Having two or all three sensory or motor deficits increased the rate of falling 3.9 times (95% confidence interval 2.1-7.0) compared with persons without these deficits. These data suggest that impaired sensory and motor function of the lower extremities plays an important role in falls in the elderly.

Personality in Parkinson's disease: Clinical, behavioural and cognitive correlates.

PubMed

Santangelo, Gabriella; Piscopo, Fausta; Barone, Paolo; Vitale, Carmine

2017-03-15

Affective disorders and personality changes have long been considered pre-motor aspects of Parkinson's disease (PD). Many authors have used the term "premorbid personality" to define distinctive features of PD patients' personality characterized by reduced exploration of new environmental stimuli or potential reward sources ("novelty seeking") and avoidance behaviour ("harm avoidance") present before motor features. The functional correlates underlying the personality changes described in PD, implicate dysfunction of meso-cortico-limbic and striatal circuits. As disease progresses, the imbalance of neurotransmitter systems secondary to degenerative processes, along with dopamine replacement therapy, can produce a reversal of behaviours and an increase in reward seeking, laying the foundations for the emergence of the impulse control disorders. Personality disorders can be interpreted, therefore, as the result of individual susceptibility arising from intrinsic degenerative processes and individual personality features, in combination with extrinsic factors such as lifestyle, PD motor dysfunction and drug treatment. For a better understanding of personality disorders observed in PD and their relationship with the prodromal stage of the disease, prospective clinical studies are needed that correlate different personality profiles with other disease progression markers. Here, we review previous studies investigating the clinical, cognitive and behavioural correlates of personality traits in PD patients. Copyright © 2017 Elsevier B.V. All rights reserved.

No evidence for mirror system dysfunction in schizophrenia from a multimodal TMS/EEG study.

PubMed

Andrews, Sophie C; Enticott, Peter G; Hoy, Kate E; Thomson, Richard H; Fitzgerald, Paul B

2015-08-30

Dysfunctional mirror neuron systems have been proposed to contribute to the social cognitive deficits observed in schizophrenia. A few studies have explored mirror systems in schizophrenia using various techniques such as TMS (levels of motor resonance) or EEG (levels of mu suppression), with mixed results. This study aimed to use a novel multimodal approach (i.e. concurrent TMS and EEG) to further investigate mirror systems and social cognition in schizophrenia. Nineteen individuals with schizophrenia or schizoaffective disorder and 19 healthy controls participated. Single-pulse TMS was applied to M1 during the observation of hand movements designed to elicit mirror system activity. Single EEG electrodes (C3, CZ, C4) recorded brain activity. Participants also completed facial affect recognition and theory of mind tasks. The schizophrenia group showed significant deficits in facial affect recognition and higher level theory of mind compared to healthy controls. A significant positive relationship was revealed between mu suppression and motor resonance for the overall sample, indicating concurrent validity of these measures. Levels of mu suppression and motor resonance were not significantly different between groups. These findings indicate that in stable outpatients with schizophrenia, mirror system functioning is intact, and therefore their social cognitive difficulties may be caused by alternative pathophysiology. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Developmental Exposure to A Commercial PBDE Mixture: Effects on Protein Networks in the Cerebellum and Hippocampus of Rats

EPA Science Inventory

BACKGROUND: Polybrominated diphenyl ethers (PBDEs) are structurally similar topolychlorinated biphenyls (PCBs) and have both central (learning and memory deficits) and peripheral (motor dysfunction) neurotoxic effects at concentrations/doses similar to those of PCBs. The cellular...

RELEVANCE OF VISUAL EFFECTS OF VOLATILE ORGANIC COMPOUNDS TO HUMAN HEALTH RISK ASSESSMENT

EPA Science Inventory

Traditional measures of neurotoxicity have included assessment of sensory, cognitive, and motor function. Visual system function and the neurobiological substrates are well characterized across species. Dysfunction in the visual system may be specific or may be surrogate for mor...

SMN regulates axonal local translation via miR-183/mTOR pathway

PubMed Central

Kye, Min Jeong; Niederst, Emily D.; Wertz, Mary H.; Gonçalves, Inês do Carmo G.; Akten, Bikem; Dover, Katarzyna Z.; Peters, Miriam; Riessland, Markus; Neveu, Pierre; Wirth, Brunhilde; Kosik, Kenneth S.; Sardi, S. Pablo; Monani, Umrao R.; Passini, Marco A.; Sahin, Mustafa

2014-01-01

Reduced expression of SMN protein causes spinal muscular atrophy (SMA), a neurodegenerative disorder leading to motor neuron dysfunction and loss. However, the molecular mechanisms by which SMN regulates neuronal dysfunction are not fully understood. Here, we report that reduced SMN protein level alters miRNA expression and distribution in neurons. In particular, miR-183 levels are increased in neurites of SMN-deficient neurons. We demonstrate that miR-183 regulates translation of mTor via direct binding to its 3′ UTR. Interestingly, local axonal translation of mTor is reduced in SMN-deficient neurons, and this can be recovered by miR-183 inhibition. Finally, inhibition of miR-183 expression in the spinal cord of an SMA mouse model prolongs survival and improves motor function of Smn-mutant mice. Together, these observations suggest that axonal miRNAs and the mTOR pathway are previously unidentified molecular mechanisms contributing to SMA pathology. PMID:25055867

Disruptions of network connectivity predict impairment in multiple behavioral domains after stroke

PubMed Central

Ramsey, Lenny E.; Metcalf, Nicholas V.; Chacko, Ravi V.; Weinberger, Kilian; Baldassarre, Antonello; Hacker, Carl D.; Shulman, Gordon L.; Corbetta, Maurizio

2016-01-01

Deficits following stroke are classically attributed to focal damage, but recent evidence suggests a key role of distributed brain network disruption. We measured resting functional connectivity (FC), lesion topography, and behavior in multiple domains (attention, visual memory, verbal memory, language, motor, and visual) in a cohort of 132 stroke patients, and used machine-learning models to predict neurological impairment in individual subjects. We found that visual memory and verbal memory were better predicted by FC, whereas visual and motor impairments were better predicted by lesion topography. Attention and language deficits were well predicted by both. Next, we identified a general pattern of physiological network dysfunction consisting of decrease of interhemispheric integration and intrahemispheric segregation, which strongly related to behavioral impairment in multiple domains. Network-specific patterns of dysfunction predicted specific behavioral deficits, and loss of interhemispheric communication across a set of regions was associated with impairment across multiple behavioral domains. These results link key organizational features of brain networks to brain–behavior relationships in stroke. PMID:27402738

Sensitivity analysis of discharge patterns of subthalamic nucleus in the model of basal ganglia in Parkinson disease.

PubMed

Singh, Jyotsna; Singh, Phool; Malik, Vikas

2017-01-01

Parkinson disease alters the information patterns in movement related pathways in brain. Experimental results performed on rats show that the activity patterns changes from single spike activity to mixed burst mode in Parkinson disease. However the cause of this change in activity pattern is not yet completely understood. Subthalamic nucleus is one of the main nuclei involved in the origin of motor dysfunction in Parkinson disease. In this paper, a single compartment conductance based model is considered which focuses on subthalamic nucleus and synaptic input from globus pallidus (external). This model shows highly nonlinear behavior with respect to various intrinsic parameters. Behavior of model has been presented with the help of activity patterns generated in healthy and Parkinson condition. These patterns have been compared by calculating their correlation coefficient for different values of intrinsic parameters. Results display that the activity patterns are very sensitive to various intrinsic parameters and calcium shows some promising results which provide insights into the motor dysfunction.

Widespread temporo-occipital lobe dysfunction in amyotrophic lateral sclerosis

NASA Astrophysics Data System (ADS)

Loewe, Kristian; Machts, Judith; Kaufmann, Jörn; Petri, Susanne; Heinze, Hans-Jochen; Borgelt, Christian; Harris, Joseph Allen; Vielhaber, Stefan; Schoenfeld, Mircea Ariel

2017-01-01

Recent studies suggest that amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) lie on a single clinical continuum. However, previous neuroimaging studies have found only limited involvement of temporal lobe regions in ALS. To better delineate possible temporal lobe involvement in ALS, the present study aimed to examine changes in functional connectivity across the whole brain, particularly with regard to extra-motor regions, in a group of 64 non-demented ALS patients and 38 healthy controls. To assess between-group differences in connectivity, we computed edge-level statistics across subject-specific graphs derived from resting-state functional MRI data. In addition to expected ALS-related decreases in functional connectivity in motor-related areas, we observed extensive changes in connectivity across the temporo-occipital cortex. Although ALS patients with comorbid FTD were deliberately excluded from this study, the pattern of connectivity alterations closely resembles patterns of cerebral degeneration typically seen in FTD. This evidence for subclinical temporal dysfunction supports the idea of a common pathology in ALS and FTD.

Firing patterns of spontaneously active motor units in spinal cord-injured subjects

PubMed Central

Zijdewind, Inge; Thomas, Christine K

2012-01-01

Involuntary motor unit activity at low rates is common in hand muscles paralysed by spinal cord injury. Our aim was to describe these patterns of motor unit behaviour in relation to motoneurone and motor unit properties. Intramuscular electromyographic activity (EMG), surface EMG and force were recorded for 30 min from thenar muscles of nine men with chronic cervical SCI. Motor units fired for sustained periods (>10 min) at regular (coefficient of variation ≤ 0.15, CV, n = 19 units) or irregular intervals (CV > 0.15, n = 14). Regularly firing units started and stopped firing independently suggesting that intrinsic motoneurone properties were important for recruitment and derecruitment. Recruitment (3.6 Hz, SD 1.2), maximal (10.2 Hz, SD 2.3, range: 7.5–15.4 Hz) and derecruitment frequencies were low (3.3 Hz, SD 1.6), as were firing rate increases after recruitment (∼20 intervals in 3 s). Once active, firing often covaried, promoting the idea that units received common inputs. Half of the regularly firing units showed a very slow decline (>40 s) in discharge before derecruitment and had interspike intervals longer than their estimated afterhyperpolarisation potential (AHP) duration (estimated by death rate and breakpoint analyses). The other units were derecruited more abruptly and had shorter estimated AHP durations. Overall, regularly firing units had longer estimated AHP durations and were weaker than irregularly firing units, suggesting they were lower threshold units. Sustained firing of units at regular rates may reflect activation of persistent inward currents, visible here in the absence of voluntary drive, whereas irregularly firing units may only respond to synaptic noise. PMID:22310313

Neuropsychological function and suicidal behavior: attention control, memory and executive dysfunction in suicide attempt.

PubMed

Keilp, J G; Gorlyn, M; Russell, M; Oquendo, M A; Burke, A K; Harkavy-Friedman, J; Mann, J J

2013-03-01

Executive dysfunction, distinct from other cognitive deficits in depression, has been associated with suicidal behavior. However, this dysfunction is not found consistently across samples. Medication-free subjects with DSM-IV major depressive episode (major depressive disorder and bipolar type I disorder) and a past history of suicidal behavior (n = 72) were compared to medication-free depressed subjects with no history of suicidal behavior (n = 80) and healthy volunteers (n = 56) on a battery of tests assessing neuropsychological functions typically affected by depression (motor and psychomotor speed, attention, memory) and executive functions reportedly impaired in suicide attempters (abstract/contingent learning, working memory, language fluency, impulse control). All of the depressed subjects performed worse than healthy volunteers on motor, psychomotor and language fluency tasks. Past suicide attempters, in turn, performed worse than depressed non-attempters on attention and memory/working memory tasks [a computerized Stroop task, the Buschke Selective Reminding Task (SRT), the Benton Visual Retention Test (VRT) and an N-back task] but not on other executive function measures, including a task associated with ventral prefrontal function (Object Alternation). Deficits were not accounted for by current suicidal ideation or the lethality of past attempts. A small subsample of those using a violent method in their most lethal attempt showed a pattern of poor executive performance. Deficits in specific components of attention control, memory and working memory were associated with suicidal behavior in a sample where non-violent attempt predominated. Broader executive dysfunction in depression may be associated with specific forms of suicidal behavior, rather than suicidal behavior per se.

Olfaction in Parkinson's disease and related disorders.

PubMed

Doty, Richard L

2012-06-01

Olfactory dysfunction is an early 'pre-clinical' sign of Parkinson's disease (PD). The present review is a comprehensive and up-to-date assessment of such dysfunction in PD and related disorders. The olfactory bulb is implicated in the dysfunction, since only those syndromes with olfactory bulb pathology exhibit significant smell loss. The role of dopamine in the production of olfactory system pathology is enigmatic, as overexpression of dopaminergic cells within the bulb's glomerular layer is a common feature of PD and most animal models of PD. Damage to cholinergic, serotonergic, and noradrenergic systems is likely involved, since such damage is most marked in those diseases with the most smell loss. When compromised, these systems, which regulate microglial activity, can influence the induction of localized brain inflammation, oxidative damage, and cytosolic disruption of cellular processes. In monogenetic forms of PD, olfactory dysfunction is rarely observed in asymptomatic gene carriers, but is present in many of those that exhibit the motor phenotype. This suggests that such gene-related influences on olfaction, when present, take time to develop and depend upon additional factors, such as those from aging, other genes, formation of α-synuclein- and tau-related pathology, or lowered thresholds to oxidative stress from toxic insults. The limited data available suggest that the physiological determinants of the early changes in PD-related olfactory function are likely multifactorial and may include the same determinants as those responsible for a number of other non-motor symptoms of PD, such as dysautonomia and sleep disturbances. Copyright © 2011 Elsevier Inc. All rights reserved.

Detail, unit 4, 1,850 horsepower (hp) synchronous pump motor manufactured ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail, unit 4, 1,850 horsepower (hp) synchronous pump motor manufactured by The Electric Products Company, Cleveland , Ohio. Pump units 1, 2, and 3 are identical to this unit. View to the west - Wellton-Mohawk Irrigation System, Pumping Plant No. 3, South of Interstate 8, Wellton, Yuma County, AZ

The Basal Ganglia and Adaptive Motor Control

NASA Astrophysics Data System (ADS)

Graybiel, Ann M.; Aosaki, Toshihiko; Flaherty, Alice W.; Kimura, Minoru

1994-09-01

The basal ganglia are neural structures within the motor and cognitive control circuits in the mammalian forebrain and are interconnected with the neocortex by multiple loops. Dysfunction in these parallel loops caused by damage to the striatum results in major defects in voluntary movement, exemplified in Parkinson's disease and Huntington's disease. These parallel loops have a distributed modular architecture resembling local expert architectures of computational learning models. During sensorimotor learning, such distributed networks may be coordinated by widely spaced striatal interneurons that acquire response properties on the basis of experienced reward.

Preferential distribution of nociceptive input to motoneurons with muscle units in the cranial portion of the upper trapezius muscle.

PubMed

Dideriksen, Jakob L; Holobar, Ales; Falla, Deborah

2016-08-01

Pain is associated with changes in the neural drive to muscles. For the upper trapezius muscle, surface electromyography (EMG) recordings have indicated that acute noxious stimulation in either the cranial or the caudal region of the muscle leads to a relative decrease in muscle activity in the cranial region. It is, however, not known if this adaption reflects different recruitment thresholds of the upper trapezius motor units in the cranial and caudal region or a nonuniform nociceptive input to the motor units of both regions. This study investigated these potential mechanisms by direct motor unit identification. Motor unit activity was investigated with high-density surface EMG signals recorded from the upper trapezius muscle of 12 healthy volunteers during baseline, control (intramuscular injection of isotonic saline), and painful (hypertonic saline) conditions. The EMG was decomposed into individual motor unit spike trains. Motor unit discharge rates decreased significantly from control to pain conditions by 4.0 ± 3.6 pulses/s (pps) in the cranial region but not in the caudal region (1.4 ± 2.8 pps; not significant). These changes were compatible with variations in the synaptic input to the motoneurons of the two regions. These adjustments were observed, irrespective of the location of noxious stimulation. These results strongly indicate that the nociceptive synaptic input is distributed in a nonuniform way across regions of the upper trapezius muscle. Copyright © 2016 the American Physiological Society.

Anatomic and physiological characteristics of the ferret lateral rectus muscle and abducens nucleus.

PubMed

Bishop, Keith N; McClung, J Ross; Goldberg, Stephen J; Shall, Mary S

2007-11-01

The ferret has become a popular model for physiological and neurodevelopmental research in the visual system. We believed it important, therefore, to study extraocular whole muscle as well as single motor unit physiology in the ferret. Using extracellular stimulation, 62 individual motor units in the ferret abducens nucleus were evaluated for their contractile characteristics. Of these motor units, 56 innervated the lateral rectus (LR) muscle alone, while 6 were split between the LR and retractor bulbi (RB) muscle slips. In addition to individual motor units, the whole LR muscle was evaluated for twitch, tetanic peak force, and fatigue. The abducens nucleus motor units showed a twitch contraction time of 15.4 ms, a mean twitch tension of 30.2 mg, and an average fusion frequency of 154 Hz. Single-unit fatigue index averaged 0.634. Whole muscle twitch contraction time was 16.7 ms with a mean twitch tension of 3.32 g. The average fatigue index of whole muscle was 0.408. The abducens nucleus was examined with horseradish peroxidase conjugated with the subunit B of cholera toxin histochemistry and found to contain an average of 183 motoneurons. Samples of LR were found to contain an average of 4,687 fibers, indicating an LR innervation ratio of 25.6:1. Compared with cat and squirrel monkeys, the ferret LR motor units contract more slowly yet more powerfully. The functional visual requirements of the ferret may explain these fundamental differences.

Preferential distribution of nociceptive input to motoneurons with muscle units in the cranial portion of the upper trapezius muscle

PubMed Central

Dideriksen, Jakob L.; Holobar, Ales

2016-01-01

Pain is associated with changes in the neural drive to muscles. For the upper trapezius muscle, surface electromyography (EMG) recordings have indicated that acute noxious stimulation in either the cranial or the caudal region of the muscle leads to a relative decrease in muscle activity in the cranial region. It is, however, not known if this adaption reflects different recruitment thresholds of the upper trapezius motor units in the cranial and caudal region or a nonuniform nociceptive input to the motor units of both regions. This study investigated these potential mechanisms by direct motor unit identification. Motor unit activity was investigated with high-density surface EMG signals recorded from the upper trapezius muscle of 12 healthy volunteers during baseline, control (intramuscular injection of isotonic saline), and painful (hypertonic saline) conditions. The EMG was decomposed into individual motor unit spike trains. Motor unit discharge rates decreased significantly from control to pain conditions by 4.0 ± 3.6 pulses/s (pps) in the cranial region but not in the caudal region (1.4 ± 2.8 pps; not significant). These changes were compatible with variations in the synaptic input to the motoneurons of the two regions. These adjustments were observed, irrespective of the location of noxious stimulation. These results strongly indicate that the nociceptive synaptic input is distributed in a nonuniform way across regions of the upper trapezius muscle. PMID:27226455

76 FR 10396 - New United Motor Manufacturing, Inc., Formerly a Joint Venture of General Motors Corporation and...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-24

... Manufacturing, Inc., Formerly a Joint Venture of General Motors Corporation and Toyota Motor Corporation, Including On- Site Leased Workers From Corestaff, ABM Janitorial, Toyota Engineering and Manufacturing North... Motor Manufacturing, Inc., formerly a joint venture of General Motors Corporation and Toyota Motor...

The 3-Second Rule in Hereditary Pure Cerebellar Ataxia: A Synchronized Tapping Study

PubMed Central

Matsuda, Shunichi; Matsumoto, Hideyuki; Furubayashi, Toshiaki; Hanajima, Ritsuko; Tsuji, Shoji; Ugawa, Yoshikazu; Terao, Yasuo

2015-01-01

The ‘3-second rule’ has been proposed based on miscellaneous observations that a time period of around 3 seconds constitutes the fundamental unit of time related to the neuro-cognitive machinery in normal humans. The aim of paper was to investigate the temporal processing in patients with spinocerebellar ataxia type 6 (SCA6) and SCA31, pure cerebellar types of spinocerebellar degeneration, using a synchronized tapping task. Seventeen SCA patients (11 SCA6, 6 SCA31) and 17 normal age-matched volunteers participated. The task required subjects to tap a keyboard in synchrony with sequences of auditory stimuli presented at fixed interstimulus intervals (ISIs) between 200 and 4800 ms. In this task, the subjects required non-motor components to estimate the time of forthcoming tone in addition to motor components to tap. Normal subjects synchronized their taps to the presented tones at shorter ISIs, whereas as the ISI became longer, the normal subjects displayed greater latency between the tone and the tapping (transition zone). After the transition zone, normal subjects pressed the button delayed relative to the tone. On the other hand, SCA patients could not synchronize their tapping with the tone even at shorter ISIs, although they pressed the button delayed relative to the tone earlier than normal subjects did. The earliest time of delayed tapping appearance after the transition zone was 4800 ms in normal subjects but 1800 ms in SCA patients. The span of temporal integration in SCA patients is shortened compared to that in normal subjects. This could represent non-motor cerebellar dysfunction in SCA patients. PMID:25706752

Axonal loss in patients with inflammatory demyelinating polyneuropathy as determined by motor unit number estimation and MUNIX.

PubMed

Paramanathan, Sansuthan; Tankisi, Hatice; Andersen, Henning; Fuglsang-Frederiksen, Anders

2016-01-01

This study quantifies functioning axons and reinnervation by applying two methods multiple point stimulation (MPS) MUNE, and motor unit number index (MUNIX), in patients with acute- and chronic inflammatory demyelinating polyneuropathy (AIDP, CIDP). Nineteen patients with inflammatory demyelinating polyneuropathy (eleven AIDP and eight CIDP) were prospectively included. MPS MUNE and MUNIX examinations on the thenar muscle group by stimulating the median nerve were applied on all patients. Motor unit size was calculated as single motor unit potential (sMUP) and motor unit size index (MUSIX). The results were compared with twenty healthy subjects. In AIDP patients mean MPS MUNE (106) and MUNIX (80) were lower than control MPS MUNE (329) and MUNIX (215) (p<0.001). In CIDP patients both MPS MUNE (88) and MUNIX (67) were lower than controls (p<0.001). In CIDP patients sMUP (63) and MUSIX (90) were higher than control sMUP (35) and MUSIX (58) (p<0.05 and p<0.01). When AIDP and CIDP groups were combined the sensitivity for MPS MUNE and MUNIX were 89.5% and 68.4%, respectively. Decreased MPS MUNE and MUNIX suggest presence of axonal loss or loss of functioning axons in AIDP and CIDP. Increased motor unit size in CIDP patients indicates compensatory reinnervation. Moreover, both MPS MUNE and MUNIX can discriminate between disease versus non-disease. Estimation of the number and the average size of motor units may have clinical value for the assessment of axonal loss or loss of functioning axons in patients with AIDP and CIDP. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Discharge properties of abductor hallucis before, during, and after an isometric fatigue task.

PubMed

Kelly, Luke A; Racinais, Sebastien; Cresswell, Andrew G

2013-08-01

Abductor hallucis is the largest muscle in the arch of the human foot and comprises few motor units relative to its physiological cross-sectional area. It has been described as a postural muscle, aiding in the stabilization of the longitudinal arch during stance and gait. The purpose of this study was to describe the discharge properties of abductor hallucis motor units during ramp and hold isometric contractions, as well as its discharge characteristics during fatigue. Intramuscular electromyographic recordings from abductor hallucis were made in 5 subjects; from those recordings, 42 single motor units were decomposed. Data were recorded during isometric ramp contractions at 60% maximum voluntary contraction (MVC), performed before and after a submaximal isometric contraction to failure (mean force 41.3 ± 15.3% MVC, mean duration 233 ± 116 s). Motor unit recruitment thresholds ranged from 10.3 to 54.2% MVC. No significant difference was observed between recruitment and derecruitment thresholds or their respective discharge rates for both the initial and postfatigue ramp contractions (all P > 0.25). Recruitment threshold was positively correlated with recruitment discharge rate (r = 0.47, P < 0.03). All motor units attained similar peak discharge rates (14.0 ± 0.25 pulses/s) and were not correlated with recruitment threshold. Thirteen motor units could be followed during the isometric fatigue task, with a decline in discharge rate and increase in discharge rate variability occurring in the final 25% of the task (both P < 0.05). We have shown that abductor hallucis motor units discharge relatively slowly and are considerably resistant to fatigue. These characteristics may be effective for generating and sustaining the substantial level of force that is required to stabilize the longitudinal arch during weight bearing.

Effect of pain on the modulation in discharge rate of sternocleidomastoid motor units with force direction.

PubMed

Falla, Deborah; Lindstrøm, Rene; Rechter, Lotte; Farina, Dario

2010-05-01

To compare the behavior of sternocleidomastoid motor units of patients with chronic neck pain and healthy controls. Nine women (age, 40.4+/-3.5 yr) with chronic neck pain and nine age- and gender-matched healthy controls participated. Surface and intramuscular EMG were recorded from the sternocleidomastoid muscle bilaterally as subjects performed isometric contractions of 10-s duration in the horizontal plane at a force of 15 N in eight directions (0-360 degrees ; 45 degrees intervals) and isometric contractions at 15 and 30 N force with continuous change in force direction in the range 0-360 degrees . Motor unit behavior was monitored during the 10-s contractions and the subsequent resting periods. The mean motor unit discharge rate depended on the direction of force in the control subjects (P<0.05) but not in the patients. Moreover, in three of the nine patients, but in none of the controls, single motor unit activity continued for 8.1+/-6.1s upon completion of the contraction. The surface EMG amplitude during the circular contraction at 15N was greater for the patients (43.5+/-54.2 microV) compared to controls (16.9+/-14.9 microV; P<0.05). The modulation in discharge rate of individual motor units with force direction is reduced in the sternocleidomastoid muscle in patients with neck pain, with some patients showing prolonged motor unit activity when they were instructed to rest. These observations suggest that chronic neck pain affects the change in neural drive to muscles with force direction. Copyright 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Discharge characteristics of biceps brachii motor units at recruitment when older adults sustained an isometric contraction.

PubMed

Pascoe, Michael A; Holmes, Matthew R; Enoka, Roger M

2011-02-01

The purpose of this study was to compare the discharge characteristics of motor units recruited during an isometric contraction that was sustained with the elbow flexor muscles by older adults at target forces that were less than the recruitment threshold force of each isolated motor unit. The discharge times of 27 single motor units were recorded from the biceps brachii in 11 old adults (78.8 ± 5.9 yr). The target force was set at either a relatively small (6.6 ± 3.7% maximum) or large (11.4 ± 4.5% maximum) difference below the recruitment threshold force and the contraction was sustained until the motor unit was recruited and discharged action potentials for about 60 s. The time to recruitment was longer for the large target-force difference (P = 0.001). At recruitment, the motor units discharged repetitively for both target-force differences, which contrasts with data from young adults when motor units discharged intermittently at recruitment for the large difference between recruitment threshold force and target force. The coefficient of variation (CV) for the first five interspike intervals (ISIs) increased from the small (18.7 ± 7.9) to large difference (35.0 ± 10.2%, P = 0.008) for the young adults, but did not differ for the two target force differences for the old adults (26.3 ± 14.7 to 24.0 ± 13.1%, P = 0.610). When analyzed across the discharge duration, the average CV for the ISI decreased similarly for the two target-force differences (P = 0.618) in old adults. These findings contrast with those of young adults and indicate that the integration of synaptic input during sustained contractions differs between young and old adults.

Effects of Barbell Deadlift Training on Submaximal Motor Unit Firing Rates for the Vastus Lateralis and Rectus Femoris

PubMed Central

Stock, Matt S.; Thompson, Brennan J.

2014-01-01

Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units. PMID:25531294

Recruitment of single human low-threshold motor units with increasing loads at different muscle lengths.

PubMed

McNulty, P A; Cresswell, A G

2004-06-01

We investigated the recruitment behaviour of low threshold motor units in flexor digitorum superficialis by altering two biomechanical constraints: the load against which the muscle worked and the initial muscle length. The load was increased using isotonic (low load), loaded dynamic (intermediate load) and isometric (high load) contractions in two studies. The initial muscle position reflected resting muscle length in series A, and a longer length with digit III fully extended in series B. Intramuscular EMG was recorded from 48 single motor units in 10 experiments on five healthy subjects, 21 units in series A and 27 in series B, while subjects performed ramp up, hold and ramp down contractions. Increasing the load on the muscle decreased the force, displacement and firing rate of single motor units at recruitment at shorter muscle lengths (P<0.001, dependent t-test). At longer muscle lengths this recruitment pattern was observed between loaded dynamic and isotonic contractions, but not between isometric and loaded dynamic contractions. Thus, the recruitment properties of single motor units in human flexor digitorum superficialis are sensitive to changes in both imposed external loads and the initial length of the muscle.

Preceding muscle activity influences motor unit discharge and rate of torque development during ballistic contractions in humans

PubMed Central

Van Cutsem, Michaël; Duchateau, Jacques

2005-01-01

To investigate the effect of initial conditions on the modulation of motor unit discharge during fast voluntary contractions, we compared ballistic isometric contractions of the ankle dorsiflexor muscles that were produced from either a resting state or superimposed on a sustained contraction. The torque of the dorsiflexors and the surface and intramuscular EMGs from the tibialis anterior were recorded. The results showed that the performance of a ballistic contraction from a sustained contraction (∼25% maximal voluntary contraction (MVC)) had a negative effect on the maximal rate of torque development. Although the electromechanical delay was shortened, the EMG activity during the ballistic contraction was less synchronized. These observations were associated with a significant decline in the average discharge rate of single motor units (89.8 ± 3.8 versus 115 ± 5.8 Hz) and in the percentage of units (6.2 versus 15.5% of the whole sample) that exhibited double discharges at brief intervals (= 5 ms). High-threshold units that were not recruited during the sustained contraction displayed the same activation pattern, which indicates that the mechanisms responsible for the decline in discharge rate were not restricted to previously activated units, but appear to influence the entire motor unit pool. When a premotor silent period (SP) was observed at the transition from the sustained muscular activity to the ballistic contraction (19% of the trials), these adjustments in motor unit activity were not present, and the ballistic contractions were similar to those performed from a resting state. Together, these results indicate that initial conditions can influence the capacity for motor unit discharge rate and hence the performance of a fast voluntary contraction. PMID:15539402

Force-frequency and fatigue properties of motor units in muscles that control digits of the human hand.

PubMed

Fuglevand, A J; Macefield, V G; Bigland-Ritchie, B

1999-04-01

Modulation of motor unit activation rate is a fundamental process by which the mammalian nervous system encodes muscle force. To identify how rate coding of force may change as a consequence of fatigue, intraneural microstimulation of motor axons was used to elicit twitch and force-frequency responses before and after 2 min of intermittent stimulation (40-Hz train for 330 ms, 1 train/s) in single motor units of human long finger flexor muscles and intrinsic hand muscles. Before fatigue, two groups of units could be distinguished based on the stimulus frequency needed to elicit half-maximal force; group 1 (n = 8) required 9.1 +/- 0.5 Hz (means +/- SD), and group 2 (n = 5) required 15.5 +/- 1.1 Hz. Twitch contraction times were significantly different between these two groups (group 1 = 66. 5 ms; group 2 = 45.9 ms). Overall 18% of the units were fatigue resistant [fatigue index (FI) > 0.75], 64% had intermediate fatigue sensitivity (0.25

Motor unit firing and its relation to tremor in the tonic vibration reflex of the decerebrate cat.

PubMed

Clark, F J; Matthews, P B; Muir, R B

1981-01-01

1. The discharge of single motor units has been recorded from the soleus muscle of the decerebrate cat during the tonic vibration reflex elicited isometrically, to further understanding of the tremor that is seen in the reflex contraction. The reflex was elicited by pulses of vibration of 50 micrometers amplitude at 150 Hz, and up to four units were studied concurrently. 2. Individual units fired rather regularly and at a low frequency (range 4-14 Hz). The rate of firing of any unit normally fell within the frequency band of the tremor recorded at the same time. On comparing different preparations a higher frequency of tremor was associated with a higher frequency of motor firing. 3. The responses of pairs of motor units recorded concurrently during repeated production of the reflex were compared by cross-correlation analysis; over 1000 spikes from each train were normally used for this. The major of the cross-correlograms were flat with no overt sign of any synchronization between the units other than that due to the vibration. 4. Clear indications of correlated motor unit firing could be produced deliberately by modulating the amplitude of vibration at a frequency comparable to that of the normal tremor and thereby introducing a rhythmic component into the tonic vibration reflex. 5. About 20% of the cross-correlograms obtained during normal tremor showed varying amounts of an irregular 'waviness' suggesting a possible correlation between the times of firing of a pair of units. But such waves never developed steadily throughout the period of analysis, in contrast to the comparable waves produced on modulating the vibration. Similar waves were seen on cross-correlating a motor unit with an electronic oscillator, confirming that their occurrence does not necessarily demonstrate the existence of active neural interactions. 6. It is concluded that there is no strong and widespread neural synchronizing mechanism active during the tonic vibration reflex, although the possibility of some weak neural interactions has not been excluded. The findings favour the idea that the tremor in this preparation is simply the inevitable result of motor units discharging asynchronously, but at closely similar subtetanic frequencies.

Determination of the motor unit behavior of lumbar erector spinae muscles through surface EMG decomposition technology in healthy female subjects.

PubMed

Silva, Mariana Felipe; Dias, Josilainne Marcelino; Pereira, Ligia Maxwell; Mazuquin, Bruno Fles; Lindley, Steven; Richards, Jim; Cardoso, Jefferson Rosa

2017-01-01

The aims of this study were to determine the motor unit behavior of the erector spinae muscles and to assess whether differences exist between the dominant/nondominant sides of the back muscles. Nine healthy women, aged 21.7 years (SD = 0.7), performed a back extension test. Surface electromyographic decomposition data were collected from both sides of the erector spinae and decomposed into individual motor unit action potential trains. The mean firing rate for each motor unit was calculated, and a regression analysis was performed against the corresponding recruitment thresholds. The mean firing rate ranged from 15.9 to 23.9 pps and 15.8 to 20.6 pps on the dominant and nondominant sides, respectively. However, the early motor unit potentials of the nondominant lumbar erector spinae muscles were recruited at a lower firing rate. This technique may further our understanding of individuals with back pain and other underlying neuromuscular diseases. Muscle Nerve 55: 28-34, 2017. © 2016 Wiley Periodicals, Inc.

Deciphering the contribution of intrinsic and synaptic currents to the effects of transient synaptic inputs on human motor unit discharge

PubMed Central

Powers, Randall K.; Türker, Kemal S.

2010-01-01

The amplitude and time course of synaptic potentials in human motoneurons can be estimated in tonically discharging motor units by measuring stimulus-evoked changes in the rate and probability of motor unit action potentials. However, in spite of the fact that some of these techniques have been used for over thirty years, there is still no consensus on the best way to estimate the characteristics of synaptic potentials or on the accuracy of these estimates. In this review, we compare different techniques for estimating synaptic potentials from human motor unit discharge and also discuss relevant animal models in which estimated synaptic potentials can be compared to those directly measured from intracellular recordings. We also review the experimental evidence on how synaptic noise and intrinsic motoneuron properties influence their responses to synaptic inputs. Finally, we consider to what extent recordings of single motor unit discharge in humans can be used to distinguish the contribution of changes in synaptic inputs versus changes in intrinsic motoneuron properties to altered motoneuron responses following CNS injury. PMID:20427230

Size principle and information theory.

PubMed

Senn, W; Wyler, K; Clamann, H P; Kleinle, J; Lüscher, H R; Müller, L

1997-01-01

The motor units of a skeletal muscle may be recruited according to different strategies. From all possible recruitment strategies nature selected the simplest one: in most actions of vertebrate skeletal muscles the recruitment of its motor units is by increasing size. This so-called size principle permits a high precision in muscle force generation since small muscle forces are produced exclusively by small motor units. Larger motor units are activated only if the total muscle force has already reached certain critical levels. We show that this recruitment by size is not only optimal in precision but also optimal in an information theoretical sense. We consider the motoneuron pool as an encoder generating a parallel binary code from a common input to that pool. The generated motoneuron code is sent down through the motoneuron axons to the muscle. We establish that an optimization of this motoneuron code with respect to its information content is equivalent to the recruitment of motor units by size. Moreover, maximal information content of the motoneuron code is equivalent to a minimal expected error in muscle force generation.

Effect of age on changes in motor units functional connectivity.

PubMed

Arjunan, Sridhar P; Kumar, Dinesh

2015-08-01

With age, there is a change in functional connectivity of motor units in muscle. This leads to reduced muscle strength. This study has investigated the effect of age on the changes in the motor unit recruitment by measuring the mutual information between multiple channels of surface electromyogram (sEMG) of biceps brachii muscle. It is hypothesised that with ageing, there is a reduction in number of motor units, which can lead to an increase in the dependency of remaining motor units. This increase can be observed in the mutual information between the multiple channels of the muscle activity. Two channels of sEMG were recorded during the maximum level of isometric contraction. 28 healthy subjects (Young: age range 20-35years and Old: age range - 60-70years) participated in the experiments. The normalized mutual information (NMI), a measure of dependency factor, was computed for the sEMG recordings. Statistical analysis was performed to test the effect of age on NMI. The results show that the NMI among the older cohort was significantly higher when compared with the young adults.

Induction of mice adult bone marrow mesenchymal stem cells into functional motor neuron-like cells.

PubMed

Abdullah, Rafal H; Yaseen, Nahi Y; Salih, Shahlaa M; Al-Juboory, Ahmad Adnan; Hassan, Ayman; Al-Shammari, Ahmed Majeed

2016-11-01

The differentiation of mesenchymal stem cells (MSC) into acetylcholine secreted motor neuron-like cells, followed by elongation of the cell axon, is a promising treatment for spinal cord injury and motor neuron cell dysfunction in mammals. Differentiation is induced through a pre-induction step using Beta- mercaptoethanol (BME) followed by four days of induction with retinoic acid and sonic hedgehog. This process results in a very efficient differentiation of BM-MSCs into motor neuron-like cells. Immunocytochemistry showed that these treated cells had specific motor neural markers: microtubule associated protein-2 and acetylcholine transferase. The ability of these cells to function as motor neuron cells was assessed by measuring acetylcholine levels in a culture media during differentiation. High-performance liquid chromatography (HPLC) showed that the differentiated cells were functional. Motor neuron axon elongation was then induced by adding different concentrations of a nerve growth factor (NGF) to the differentiation media. Using a collagen matrix to mimic the natural condition of neural cells in a three-dimensional model showed that the MSCs were successfully differentiated into motor neuron-like cells. This process can efficiently differentiate MSCs into functional motor neurons that can be used for autologous nervous system therapy and especially for treating spinal cord injuries. Copyright © 2016 Elsevier B.V. All rights reserved.

Social defeat leads to changes in the endocannabinoid system: An overexpression of calreticulin and motor impairment in mice.

PubMed

Tomas-Roig, J; Piscitelli, F; Gil, V; Del Río, J A; Moore, T P; Agbemenyah, H; Salinas-Riester, G; Pommerenke, C; Lorenzen, S; Beißbarth, T; Hoyer-Fender, S; Di Marzo, V; Havemann-Reinecke, U

2016-04-15

Prolonged and sustained stimulation of the hypothalamo-pituitary-adrenal axis have adverse effects on numerous brain regions, including the cerebellum. Motor coordination and motor learning are essential for animal and require the regulation of cerebellar neurons. The G-protein-coupled cannabinoid CB1 receptor coordinates synaptic transmission throughout the CNS and is of highest abundance in the cerebellum. Accordingly, the aim of this study was to investigate the long-lasting effects of chronic psychosocial stress on motor coordination and motor learning, CB1 receptor expression, endogenous cannabinoid ligands and gene expression in the cerebellum. After chronic psychosocial stress, motor coordination and motor learning were impaired as indicated the righting reflex and the rota-rod. The amount of the endocannabinoid 2-AG increased while CB1 mRNA and protein expression were downregulated after chronic stress. Transcriptome analysis revealed 319 genes differentially expressed by chronic psychosocial stress in the cerebellum; mainly involved in synaptic transmission, transmission of nerve impulse, and cell-cell signaling. Calreticulin was validated as a stress candidate gene. The present study provides evidence that chronic stress activates calreticulin and might be one of the pathological mechanisms underlying the motor coordination and motor learning dysfunctions seen in social defeat mice. Copyright © 2016 Elsevier B.V. All rights reserved.

Common input to motor units of intrinsic and extrinsic hand muscles during two-digit object hold.

PubMed

Winges, Sara A; Kornatz, Kurt W; Santello, Marco

2008-03-01

Anatomical and physiological evidence suggests that common input to motor neurons of hand muscles is an important neural mechanism for hand control. To gain insight into the synaptic input underlying the coordination of hand muscles, significant effort has been devoted to describing the distribution of common input across motor units of extrinsic muscles. Much less is known, however, about the distribution of common input to motor units belonging to different intrinsic muscles and to intrinsic-extrinsic muscle pairs. To address this void in the literature, we quantified the incidence and strength of near-simultaneous discharges of motor units residing in either the same or different intrinsic hand muscles (m. first dorsal, FDI, and m. first palmar interosseus, FPI) during two-digit object hold. To extend the characterization of common input to pairs of extrinsic muscles (previous work) and pairs of intrinsic muscles (present work), we also recorded electromyographic (EMG) activity from an extrinsic thumb muscle (m. flexor pollicis longus, FPL). Motor-unit synchrony across FDI and FPI was weak (common input strength, CIS, mean +/- SE: 0.17 +/- 0.02). Similarly, motor units from extrinsic-intrinsic muscle pairs were characterized by weak synchrony (FPL-FDI: 0.25 +/- 0.02; FPL-FPI: 0.29 +/- 0.03) although stronger than FDI-FPI. Last, CIS from within FDI and FPI was more than three times stronger (0.70 +/- 0.06 and 0.66 +/- 0.06, respectively) than across these muscles. We discuss present and previous findings within the framework of muscle-pair specific distribution of common input to hand muscles based on their functional role in grasping.

New Angles on Motor and Sensory Coordination in Learning Disabilities.

ERIC Educational Resources Information Center

Goldey, Ellen S.

1998-01-01

Provides an overview of presentations that were included in the Medical Symposium at the 1998 Learning Disabilities Association conference. The symposium addressed vestibular control and eye movement, postural sway and balance, cerebellar dysfunction, the role of the frontal lobe, developmental coordination disorder, and sensory integration…

Neurocognitive Effects of HIV Infection on Young Children: Implications for Assessment.

ERIC Educational Resources Information Center

Landry, Kris; Smith, Tina

1998-01-01

Describes the various direct and indirect effects of HIV and AIDS on children's development and the implications for early intervention assessment. HIV and AIDS effects include disorganization during the neonatal period, failure to thrive, motor difficulties, cognitive dysfunction, expressive language behavior, attention problems, and…

Gastrostomy placement improves height and weight gain in girls with Rett syndrome

USDA-ARS?s Scientific Manuscript database

Growth failure and undernutrition complicate the clinical course of girls with Rett syndrome (RTT). These abnormalities are, in part, the consequence of oral motor dysfunction and inadequate dietary intake. We hypothesized that gastrostomy placement for nutritional therapy reverses the decline in he...

Innervation zones of fasciculating motor units: observations by a linear electrode array

PubMed Central

Jahanmiri-Nezhad, Faezeh; Barkhaus, Paul E.; Rymer, William Z.; Zhou, Ping

2015-01-01

This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs. PMID:26029076

MPP+-Lesioned Mice: an Experimental Model of Motor, Emotional, Memory/Learning, and Striatal Neurochemical Dysfunctions.

PubMed

Cunha, Mauricio P; Pazini, Francis L; Lieberknecht, Vicente; Budni, Josiane; Oliveira, Ágatha; Rosa, Júlia M; Mancini, Gianni; Mazzardo, Leidiane; Colla, André R; Leite, Marina C; Santos, Adair R S; Martins, Daniel F; de Bem, Andreza F; Gonçalves, Carlos Alberto S; Farina, Marcelo; Rodrigues, Ana Lúcia S

2017-10-01

The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces motor and nonmotor dysfunctions resembling Parkinson's disease (PD); however, studies investigating the effects of 1-methyl-4-phenylpyridinium (MPP + ), an active oxidative product of MPTP, are scarce. This study investigated the behavioral and striatal neurochemical changes (related to oxidative damage, glial markers, and neurotrophic factors) 24 h after intracerebroventricular administration of MPP + (1.8-18 μg/mouse) in C57BL6 mice. MPP + administration at high dose (18 μg/mouse) altered motor parameters, since it increased the latency to leave the first quadrant and reduced crossing, rearing, and grooming responses in the open-field test and decreased rotarod latency time. MPP + administration at low dose (1.8 μg/mouse) caused specific nonmotor dysfunctions as it produced a depressive-like effect in the forced swim test and tail suspension test, loss of motivational and self-care behavior in the splash test, anxiety-like effect in the elevated plus maze test, and short-term memory deficit in the step-down inhibitory avoidance task, without altering ambulation. MPP + at doses of 1.8-18 μg/mouse increased tyrosine hydroxylase (TH) immunocontent and at 18 μg/mouse increased α-synuclein and decreased parkin immunocontent. The astrocytic calcium-binding protein S100B and glial fibrillary acidic protein (GFAP)/S100B ratio was decreased following MPP + administration (18 μg/mouse). At this highest dose, MPP + increased the ionized calcium-binding adapter molecule 1 (Iba-1) immunocontent, suggesting microglial activation. Also, MPP + at a dose of 18 μg/mouse increased thiobarbituric acid reactive substances (TBARS) and glutathione (GSH) levels and increased glutathione peroxidase (GPx) and hemeoxygenase-1 (HO-1) immunocontent, suggesting a significant role for oxidative stress in the MPP + -induced striatal damage. MPP + (18 μg/mouse) also increased striatal fibroblast growth factor 2 (FGF-2) and brain-derived neurotrophic factor (BDNF) levels. Moreover, MPP + decreased tropomyosin receptor kinase B (TrkB) immunocontent. Finally, MPP + (1.8-18 μg/mouse) increased serum corticosterone levels and did not alter acetylcholinesterase (AChE) activity in the striatum but increased it in cerebral cortex and hippocampus. Collectively, these results indicate that MPP + administration at low doses may be used as a model of emotional and memory/learning behavioral deficit related to PD and that MPP + administration at high dose could be useful for analysis of striatal dysfunctions associated with motor deficits in PD.

Load-dependent assembly of the bacterial flagellar motor.

PubMed

Tipping, Murray J; Delalez, Nicolas J; Lim, Ren; Berry, Richard M; Armitage, Judith P

2013-08-20

It is becoming clear that the bacterial flagellar motor output is important not only for bacterial locomotion but also for mediating the transition from liquid to surface living. The output of the flagellar motor changes with the mechanical load placed on it by the external environment: at a higher load, the motor runs more slowly and produces higher torque. Here we show that the number of torque-generating units bound to the flagellar motor also depends on the external mechanical load, with fewer stators at lower loads. Stalled motors contained at least as many stators as rotating motors at high load, indicating that rotation is unnecessary for stator binding. Mutant stators incapable of generating torque could not be detected around the motor. We speculate that a component of the bacterial flagellar motor senses external load and mediates the strength of stator binding to the rest of the motor. The transition between liquid living and surface living is important in the life cycles of many bacteria. In this paper, we describe how the flagellar motor, used by bacteria for locomotion through liquid media and across solid surfaces, is capable of adjusting the number of bound stator units to better suit the external load conditions. By stalling motors using external magnetic fields, we also show that rotation is not required for maintenance of stators around the motor; instead, torque production is the essential factor for motor stability. These new results, in addition to previous data, lead us to hypothesize that the motor stators function as mechanosensors as well as functioning as torque-generating units.

A causal test of the motor theory of speech perception: a case of impaired speech production and spared speech perception.

PubMed

Stasenko, Alena; Bonn, Cory; Teghipco, Alex; Garcea, Frank E; Sweet, Catherine; Dombovy, Mary; McDonough, Joyce; Mahon, Bradford Z

2015-01-01

The debate about the causal role of the motor system in speech perception has been reignited by demonstrations that motor processes are engaged during the processing of speech sounds. Here, we evaluate which aspects of auditory speech processing are affected, and which are not, in a stroke patient with dysfunction of the speech motor system. We found that the patient showed a normal phonemic categorical boundary when discriminating two non-words that differ by a minimal pair (e.g., ADA-AGA). However, using the same stimuli, the patient was unable to identify or label the non-word stimuli (using a button-press response). A control task showed that he could identify speech sounds by speaker gender, ruling out a general labelling impairment. These data suggest that while the motor system is not causally involved in perception of the speech signal, it may be used when other cues (e.g., meaning, context) are not available.

Self-Reported Symptoms of Parkinson's Disease by Sex and Disease Duration.

PubMed

Shin, Ju Young; Pohlig, Ryan T; Habermann, Barbara

2017-11-01

Parkinson's disease (PD) is a neurodegenerative disease with a wide range of symptom presentations. The purpose of this research was to compare self-reported motor and non-motor symptoms of PD by sex and disease duration. This study was a cross-sectional descriptive survey in community-dwelling people with PD. A total of 141 participants (64.6% response rate; 59.6% men; M age = 69.7 years) were included. Males reported more rigidity, speech problems, sexual dysfunction, memory problems, and socializing problems than females. The number of motor symptoms in three groups divided by increments of 5 years was significantly increased. Postural instability, freezing, off periods, dyskinesia, speech problems, and hallucinations/psychosis were significantly increased as the disease duration increased. Thorough assessment of motor and non-motor symptoms could decrease the risk of inadequate symptom management. Provision of information regarding PD symptoms at each stage may help people with PD and their caregivers in planning their future care and life.

Basal Ganglia Contributions to Motor Control: A Vigorous Tutor

PubMed Central

Turner, Robert S.; Desmurget, Michel

2010-01-01

SUMMARY OF RECENT ADVANCES The roles of the basal ganglia (BG) in motor control are much debated. Many influential hypotheses have grown from studies in which output signals of the BG were not blocked, but pathologically-disturbed. A weakness of that approach is that the resulting behavioral impairments reflect degraded function of the BG per se mixed together with secondary dysfunctions of BG-recipient brain areas. To overcome that limitation, several studies have focused on the main skeletomotor output region of the BG, the globus pallidus internus (GPi). Using single-cell recording and inactivation protocols these studies provide consistent support for two hypotheses: the BG modulates movement performance (“vigor”) according to motivational factors (i.e., context-specific cost/reward functions) and the BG contributes to motor learning. Results from these studies also add to the problems that confront theories positing that the BG selects movement, inhibits unwanted motor responses, corrects errors online, or stores and produces well-learned motor skills. PMID:20850966

Self-Reported Symptoms of Parkinson’s Disease by Sex and Disease Duration

PubMed Central

Shin, Ju Young; Pohlig, Ryan T.; Habermann, Barbara

2017-01-01

Parkinson’s disease (PD) is a neurodegenerative disease with a wide range of symptom presentations. The purpose of this research was to compare self-reported motor and non-motor symptoms of PD by sex and disease duration. This study was a cross-sectional descriptive survey in community-dwelling people with PD. A total of 141 participants (64.6% response rate; 59.6% men; Mage = 69.7 years) were included. Males reported more rigidity, speech problems, sexual dysfunction, memory problems, and socializing problems than females. The number of motor symptoms in three groups divided by increments of 5 years was significantly increased. Postural instability, freezing, off periods, dyskinesia, speech problems, and hallucinations/psychosis were significantly increased as the disease duration increased. Thorough assessment of motor and non-motor symptoms could decrease the risk of inadequate symptom management. Provision of information regarding PD symptoms at each stage may help people with PD and their caregivers in planning their future care and life. PMID:27664144

Immediate improvement of motor function after epilepsy surgery in congenital hemiparesis.

PubMed

Pascoal, Tharick; Paglioli, Eliseu; Palmini, André; Menezes, Rafael; Staudt, Martin

2013-08-01

Hemispherectomy often leads to a loss of contralateral hand function. In some children with congenital hemiparesis, however, paretic hand function remains unchanged. An immediate improvement of hand function has never been reported. A 17-year-old boy with congenital hemiparesis and therapy-refractory seizures due to a large infarction in the territory of the middle cerebral artery underwent epilepsy surgery. Intraoperatively, electrical cortical stimulation of the affected hemisphere demonstrated preserved motor projections from the sensorimotor cortex to the (contralateral) paretic hand. A frontoparietal resection was performed, which included a complete disconnection of all motor projections originating in the sensorimotor cortex of the affected hemisphere. Surprisingly, the paretic hand showed a significant functional improvement immediately after the operation. This observation demonstrates that, in congenital hemiparesis, crossed motor projections from the affected hemisphere are not always beneficial, but can be dysfunctional, interfering with ipsilateral motor control over the paretic hand by the contralesional hemisphere. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

Plants and phytochemicals for Huntington's disease.

PubMed

Choudhary, Sunayna; Kumar, Puneet; Malik, Jai

2013-07-01

Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive motor dysfunction, including chorea and dystonia, emotional disturbances, memory, and weight loss. The medium spiny neurons of striatum and cortex are mainly effected in HD. Various hypotheses, including molecular genetics, oxidative stress, excitotoxicity, metabolic dysfunction, and mitochondrial impairment have been proposed to explain the pathogenesis of neuronal dysfunction and cell death. Despite no treatment is available to fully stop the progression of the disease, there are treatments available to help control the chorea. The present review deals with brief pathophysiology of the disease, plants and phytochemicals that have shown beneficial effects against HD like symptoms. The literature for the current review was collected using various databases such as Science direct, Pubmed, Scopus, Sci-finder, Google Scholar, and Cochrane database with a defined search strategy.

Large-Scale Brain Systems in ADHD: Beyond the Prefrontal-Striatal Model

PubMed Central

Castellanos, F. Xavier; Proal, Erika

2012-01-01

Attention-deficit/hyperactivity disorder (ADHD) has long been thought to reflect dysfunction of prefrontal-striatal circuitry, with involvement of other circuits largely ignored. Recent advances in systems neuroscience-based approaches to brain dysfunction enable the development of models of ADHD pathophysiology that encompass a number of different large-scale “resting state” networks. Here we review progress in delineating large-scale neural systems and illustrate their relevance to ADHD. We relate frontoparietal, dorsal attentional, motor, visual, and default networks to the ADHD functional and structural literature. Insights emerging from mapping intrinsic brain connectivity networks provide a potentially mechanistic framework for understanding aspects of ADHD, such as neuropsychological and behavioral inconsistency, and the possible role of primary visual cortex in attentional dysfunction in the disorder. PMID:22169776

Treatment of autonomic dysfunction in Parkinson disease and other synucleinopathies.

PubMed

Palma, Jose-Alberto; Kaufmann, Horacio

2018-03-01

Dysfunction of the autonomic nervous system afflicts most patients with Parkinson disease and other synucleinopathies such as dementia with Lewy bodies, multiple system atrophy, and pure autonomic failure, reducing quality of life and increasing mortality. For example, gastrointestinal dysfunction can lead to impaired drug pharmacodynamics causing a worsening in motor symptoms, and neurogenic orthostatic hypotension can cause syncope, falls, and fractures. When recognized, autonomic problems can be treated, sometimes successfully. Discontinuation of potentially causative/aggravating drugs, patient education, and nonpharmacological approaches are useful and should be tried first. Pathophysiology-based pharmacological treatments that have shown efficacy in controlled trials of patients with synucleinopathies have been approved in many countries and are key to an effective management. Here, we review the treatment of autonomic dysfunction in patients with Parkinson disease and other synucleinopathies, summarize the nonpharmacological and current pharmacological therapeutic strategies including recently approved drugs, and provide practical advice and management algorithms for clinicians, with focus on neurogenic orthostatic hypotension, supine hypertension, dysphagia, sialorrhea, gastroparesis, constipation, neurogenic overactive bladder, underactive bladder, and sexual dysfunction. © 2018 International Parkinson and Movement Disorder Society. © 2018 International Parkinson and Movement Disorder Society.

Vibration influence on control of single motor unit activity.

PubMed

Malouin, F; Simard, T

1978-03-01

Effects of vibratory stimulation and maximal isometric contraction on a fine motor control task were evaluated in 17 human subjects. Electromyographic audiovisual feedback cues derived from two fine-wire bipolar electrodes, inserted to a depth of 12 and 6 mm respectively, were used to train the subjects to isolate a motor unit in the extensor carpi radialis brevis muscle. A specially designed compressed air driven vibrator providing vibratory stimulation with an amplitude of 2 mm and a frequency range of 120-160 cycles per second was applied to the muscle tendon. A significant decrease was found in the subjects; ability to isolate the pretest motor unit during and after continuous and interrupted periods of vibration and following a maximal isometric contraction of the extensor carpi radials brevis muscle. Individual variations in the subjects' responses to the forms of application of the vibratory stimulus, electrode preference and feedback specificity were observed. Results suggest that marked spatial recruitment of motor units, brought into action by the vibration stimulus or by the maximal isometric contraction, interfered with inhibitory mechanisms necessary to achieve isolation and control of a single motor unit. A therapeutic application of vibration, based on the marked spatial recruitment observed during and after vibration, is proposed for muscle reeducation.

Videofluoroscopy in motor neurone disease prior to cricopharyngeal myotomy.

PubMed Central

Wilson, P. S.; Bruce-Lockhart, F. J.; Johnson, A. P.

1990-01-01

Cricopharyngeal myotomy is a recognised treatment for the dysphagia in motor neurone disease, although the results are sometimes disappointing. In this study, 27 patients with motor neurone disease causing significant dysphagia have been investigated by the technique of videofluoroscopy, in order to determine the nature of their swallowing disability; those patients found suitable have been offered cricopharyngeal myotomy. Of the 27 patients, only seven were found to have cricopharyngeal dysfunction as the predominant disability and, of these, six underwent myotomy, resulting in relief of dysphagia in five, three of whom returned to a near normal diet. Previous studies showed poor overall benefit from cricopharyngeal myotomy. Videofluoroscopy allows accurate patient selection, and a much improved outcome in the selected group. PMID:2241057

Cerebral network deficits in post-acute catatonic schizophrenic patients measured by fMRI.

PubMed

Scheuerecker, J; Ufer, S; Käpernick, M; Wiesmann, M; Brückmann, H; Kraft, E; Seifert, D; Koutsouleris, N; Möller, H J; Meisenzahl, E M

2009-03-01

Twelve patients with catatonic schizophrenia and 12 matched healthy controls were examined with functional MRI while performing a motor task. The aim of our study was to identify the intracerebral pathophysiological correlates of motor symptoms in catatonic patients. The motor task included three conditions: a self-initiated (SI), an externally triggered (ET) and a rest condition. Statistical analysis was performed with SPM5. During the self-initiated movements patients showed significantly less activation than healthy controls in the supplementary motor area (SMA), the prefrontal and parietal cortex. Our results suggest a dysfunction of the "medial motor system" in catatonic patients. Self-initiated and externally triggered movements are mediated by different motor loops. The "medial loop" includes the SMA, thalamus and basal ganglia, and is necessary for self-initiated movements. The "lateral loop" includes parts of the cerebellum, lateral premotor cortex, thalamus and parietal association areas. It is involved in the execution of externally triggered movements. Our findings are in agreement with earlier behavioral data, which show deficits in self-initiated movements in catatonic patients but no impairment of externally triggered movements.

Tetrahydrobiopterin in antenatal brain hypoxia-ischemia-induced motor impairments and cerebral palsy.

PubMed

Vasquez-Vivar, Jeannette; Shi, Zhongjie; Luo, Kehuan; Thirugnanam, Karthikeyan; Tan, Sidhartha

2017-10-01

Antenatal brain hypoxia-ischemia, which occurs in cerebral palsy, is considered a significant cause of motor impairments in children. The mechanisms by which antenatal hypoxia-ischemia causes brain injury and motor deficits still need to be elucidated. Tetrahydrobiopterin is an important enzyme cofactor that is necessary to produce neurotransmitters and to maintain the redox status of the brain. A genetic deficiency of this cofactor from mutations of biosynthetic or recycling enzymes is a well-recognized factor in the development of childhood neurological disorders characterized by motor impairments, developmental delay, and encephalopathy. Experimental hypoxia-ischemia causes a decline in the availability of tetrahydrobiopterin in the immature brain. This decline coincides with the loss of brain function, suggesting this occurrence contributes to neuronal dysfunction and motor impairments. One possible mechanism linking tetrahydrobiopterin deficiency, hypoxia-ischemia, and neuronal injury is oxidative injury. Evidence of the central role of the developmental biology of tetrahydrobiopterin in response to hypoxic ischemic brain injury, especially the development of motor deficits, is discussed. Copyright © 2017. Published by Elsevier B.V.

Identification of neuromotor deficits common to autism spectrum disorder and attention deficit/hyperactivity disorder, and imitation deficits specific to autism spectrum disorder.

PubMed

Biscaldi, Monica; Rauh, Reinhold; Müller, Cora; Irion, Lisa; Saville, Christopher W N; Schulz, Eberhard; Klein, Christoph

2015-12-01

Deficits in motor and imitation abilities are a core finding in autism spectrum disorders (ASD), but impaired motor functions are also found in attention deficit/hyperactivity disorder (ADHD). Given recent theorising about potential aetiological overlap between the two disorders, the present study aimed to assess difficulties in motor performance and imitation of facial movements and meaningless gestures in a sample of 24 ADHD patients, 22 patients with ASD, and 20 typically developing children, matched for age (6-13 years) and similar in IQ (>80). Furthermore, we explored the impact of comorbid ADHD symptoms on motor and imitation performance in the ASD sample and the interrelationships between the two groups of variables in the clinical groups separately. The results show motor dysfunction was common to both disorders, but imitation deficits were specific to ASD. Together with the pattern of interrelated motor and imitation abilities, which we found exclusively in the ASD group, our findings suggest complex phenotypic, and possibly aetiological, relationships between the two neurodevelopmental conditions.

Research of subdivision driving technology for brushless DC motors in optical fiber positioning

NASA Astrophysics Data System (ADS)

Kan, Yi; Gu, Yonggang; Zhu, Ye; Zhai, Chao

2016-07-01

In fiber spectroscopic telescopes, optical fiber positioning units are used to position thousands of fibers on the focal plane quickly and precisely. Stepper motors are used in existing units, however, it has some inherent deficiencies, such as serious heating and low efficiency. In this work, the universally adopted subdivision driving technology for stepper motors is transplanted to brushless DC motors. It keeps the advantages of stepper motors such as high positioning accuracy and resolution, while overcomes the disadvantages mentioned above. Thus, this research mainly focuses on develop a novel subdivision driving technology for brushless DC motor. By the proving of experiments of online debug and subdivision speed and position, the proposed brushless DC motor subdivision technology can achieve the expected functions.

Long-term neurodevelopmental outcomes in school-aged children after neonatal arterial switch operation.

PubMed

Hövels-Gürich, Hedwig H; Seghaye, Marie-Christine; Schnitker, Ralph; Wiesner, Magdalene; Huber, Walter; Minkenberg, Ralf; Kotlarek, Franz; Messmer, Bruno J; Von Bernuth, Götz

2002-09-01

Neurodevelopmental status of children between 8 and 14 years of age after neonatal arterial switch operation for transposition of the great arteries has not previously been systematically evaluated. Within a longitudinal study, 60 unselected children operated on as neonates with combined deep hypothermic circulatory arrest and low-flow cardiopulmonary bypass were reevaluated at the age of 7.9 to 14.3 years (mean +/- SD 10.5 +/- 1.6 years). Clinical neurologic status and standardized tests to assess gross motor function, intelligence, acquired abilities, language, and speech were carried out, and the results were related to preoperative, perioperative, and postoperative status, to management, and to neurodevelopmental status at a mean age of 5.4 years. Neurologic and speech impairments were evidently more frequent (27% and 40%, respectively) than in the general population. Intelligence and socioeconomic status were not different (P =.29 and P =.11), whereas motor function, acquired abilities, and language were reduced (P < or =.04 for each). Overall rate of developmental impairment in one or more domains was 55%, compared with 26% at age 5.4 years. Multivariable analysis showed that severe preoperative acidosis and hypoxia predicted reduced motor function (mean deficit 52.7 points, P <.001), whereas longer bypass duration predicted both neurologic (odds ratio per 10 minutes of bypass duration 1.8, P =.04) and speech (odds ratio per 10 minutes of bypass duration 1.9, P =.02) dysfunction, and perioperative and postoperative cardiocirculatory insufficiency predicted neurologic (odds ratio 6.5, P =.04) and motor (mean deficit 6.8 points, P =.03) dysfunction. The neonatal arterial switch operation with combined circulatory arrest and low-flow bypass is associated increasingly with age, with reduced neurodevelopmental outcome but not with cognitive dysfunction. In our experience, the risk of long-term neurodevelopmental impairment after neonatal corrective cardiac surgery is related to deleterious effects of the global perioperative management and to special adverse effects of prolonged bypass duration. Severe preoperative acidosis and hypoxia and postoperative hemodynamic instability must be considered as important additional risk factors.

Response inhibition rapidly increases single-neuron responses in the subthalamic nucleus of patients with Parkinson's disease.

PubMed

Benis, Damien; David, Olivier; Piallat, Brigitte; Kibleur, Astrid; Goetz, Laurent; Bhattacharjee, Manik; Fraix, Valérie; Seigneuret, Eric; Krack, Paul; Chabardès, Stéphan; Bastin, Julien

2016-11-01

The subthalamic nucleus (STN) plays a critical role during action inhibition, perhaps by acting like a fast brake on the motor system when inappropriate responses have to be rapidly suppressed. However, the mechanisms involving the STN during motor inhibition are still unclear, particularly because of a relative lack of single-cell responses reported in this structure in humans. In this study, we used extracellular microelectrode recordings during deep brain stimulation surgery in patients with Parkinson's disease (PD) to study STN neurophysiological correlates of inhibitory control during a stop signal task. We found two neuronal subpopulations responding either during motor execution (GO units) or during motor inhibition (STOP units). GO units fired selectively before patients' motor responses whereas STOP units fired selectively when patients successfully withheld their move at a latency preceding the duration of the inhibition process. These results provide electrophysiological evidence for the hypothesized role of the STN in current models of response inhibition. Copyright © 2016. Published by Elsevier Ltd.

Multi-organ autonomic dysfunction in Parkinson disease

PubMed Central

2010-01-01

Both pathologic and clinical studies of autonomic pathways have expanded the concept of Parkinson disease (PD) from a movement disorder to a multi-level widespread neurodegenerative process with non-motor features spanning several organ systems. This review integrates neuropathologic findings and autonomic physiology in PD as it relates to end organ autonomic function. Symptoms, pathology and physiology of the cardiovascular, skin/sweat gland, urinary, gastrointestinal, pupillary and neuroendocrine systems can be probed by autopsy, biopsy and non-invasive electrophysiological techniques in vivo which assess autonomic anatomy and function. There is mounting evidence that PD affects a chain of neurons in autonomic pathways. Consequently, autonomic physiology may serve as a window into non-motor PD progression and allow the development of mechanistically based treatment strategies for several non-motor features of PD. End-organ physiologic markers may be used to inform a model of PD pathophysiology and non-motor progression. PMID:20851033

A COMPUTATIONAL MODEL OF MOTOR NEURON DEGENERATION

PubMed Central

Le Masson, Gwendal; Przedborski, Serge; Abbott, L.F.

2014-01-01

SUMMARY To explore the link between bioenergetics and motor neuron degeneration, we used a computational model in which detailed morphology and ion conductance are paired with intracellular ATP production and consumption. We found that reduced ATP availability increases the metabolic cost of a single action potential and disrupts K+/Na+ homeostasis, resulting in a chronic depolarization. The magnitude of the ATP shortage at which this ionic instability occurs depends on the morphology and intrinsic conductance characteristic of the neuron. If ATP shortage is confined to the distal part of the axon, the ensuing local ionic instability eventually spreads to the whole neuron and involves fasciculation-like spiking events. A shortage of ATP also causes a rise in intracellular calcium. Our modeling work supports the notion that mitochondrial dysfunction can account for salient features of the paralytic disorder amyotrophic lateral sclerosis, including motor neuron hyperexcitability, fasciculation, and differential vulnerability of motor neuron subpopulations. PMID:25088365

A computational model of motor neuron degeneration.

PubMed

Le Masson, Gwendal; Przedborski, Serge; Abbott, L F

2014-08-20

To explore the link between bioenergetics and motor neuron degeneration, we used a computational model in which detailed morphology and ion conductance are paired with intracellular ATP production and consumption. We found that reduced ATP availability increases the metabolic cost of a single action potential and disrupts K+/Na+ homeostasis, resulting in a chronic depolarization. The magnitude of the ATP shortage at which this ionic instability occurs depends on the morphology and intrinsic conductance characteristic of the neuron. If ATP shortage is confined to the distal part of the axon, the ensuing local ionic instability eventually spreads to the whole neuron and involves fasciculation-like spiking events. A shortage of ATP also causes a rise in intracellular calcium. Our modeling work supports the notion that mitochondrial dysfunction can account for salient features of the paralytic disorder amyotrophic lateral sclerosis, including motor neuron hyperexcitability, fasciculation, and differential vulnerability of motor neuron subpopulations. Copyright © 2014 Elsevier Inc. All rights reserved.

Associations between motor unit action potential parameters and surface EMG features.

PubMed

Del Vecchio, Alessandro; Negro, Francesco; Felici, Francesco; Farina, Dario

2017-10-01

The surface interference EMG signal provides some information on the neural drive to muscles. However, the association between neural drive to muscle and muscle activation has long been debated with controversial indications due to the unavailability of motor unit population data. In this study, we clarify the potential and limitations of interference EMG analysis to infer motor unit recruitment strategies with an experimental investigation of several concurrently active motor units and of the associated features of the surface EMG. For this purpose, we recorded high-density surface EMG signals during linearly increasing force contractions of the tibialis anterior muscle, up to 70% of maximal force. The recruitment threshold (RT), conduction velocity (MUCV), median frequency (MDF MU ), and amplitude (RMS MU ) of action potentials of 587 motor units from 13 individuals were assessed and associated with features of the interference EMG. MUCV was positively associated with RT ( R 2 = 0.64 ± 0.14), whereas MDF MU and RMS MU showed a weaker relation with RT ( R 2 = 0.11 ± 0.11 and 0.39 ± 0.24, respectively). Moreover, the changes in average conduction velocity estimated from the interference EMG predicted well the changes in MUCV ( R 2 = 0.71), with a strong association to ankle dorsiflexion force ( R 2 = 0.81 ± 0.12). Conversely, both the average EMG MDF and RMS were poorly associated with motor unit recruitment. These results clarify the limitations of EMG spectral and amplitude analysis in inferring the neural strategies of muscle control and indicate that, conversely, the average conduction velocity could provide relevant information on these strategies. NEW & NOTEWORTHY The surface EMG provides information on the neural drive to muscles. However, the associations between EMG features and neural drive have been long debated due to unavailability of motor unit population data. Here, by using novel highly accurate decomposition of the EMG, we related motor unit population behavior to a wide range of voluntary forces. The results fully clarify the potential and limitation of the surface EMG to provide estimates of the neural drive to muscles. Copyright © 2017 the American Physiological Society.

Changes in force, surface and motor unit EMG during post-exercise development of low frequency fatigue in vastus lateralis muscle.

PubMed

de Ruiter, C J; Elzinga, M J H; Verdijk, P W L; van Mechelen, W; de Haan, A

2005-08-01

We investigated the effects of low frequency fatigue (LFF) on post-exercise changes in rectified surface EMG (rsEMG) and single motor unit EMG (smuEMG) in vastus lateralis muscle (n = 9). On two experimental days the knee extensors were fatigued with a 60-s-isometric contraction (exercise) at 50% maximal force capacity (MFC). On the first day post-exercise (15 s, 3, 9, 15, 21 and 27 min) rsEMG and electrically-induced (surface stimulation) forces were investigated. SmuEMG was obtained on day two. During short ramp and hold (5 s) contractions at 50% MFC, motor unit discharges of the same units were followed over time. Post-exercise MFC and tetanic force (100 Hz stimulation) recovered to about 90% of the pre-exercise values, but recovery with 20 Hz stimulation was less complete: the 20-100 Hz force ratio (mean +/- SD) decreased from 0.65+/-0.06 (pre-exercise) to 0.56+/-0.04 at 27 min post-exercise (P<0.05), indicative of LFF. At 50% MFC, pre-exercise rsEMG (% pre-exercise maximum) and motor unit discharge rate were 51.1 +/- 12.7% and 14.1 +/- 3.7 (pulses per second; pps) respectively, 15 s post-exercise the respective values were 61.4 +/- 15.4% (P<0.05) and 13.2 +/- 5.6 pps (P>0.05). Thereafter, rsEMG (at 50% MFC) remained stable but motor unit discharge rate significantly increased to 17.7 +/- 3.9 pps 27 min post-exercise. The recruitment threshold decreased (P<0.05) from 27.7 +/- 6.6% MFC before exercise to 25.2 +/- 6.7% 27 min post-exercise. The increase in discharge rate was significantly greater than could be expected from the decrease in recruitment threshold. Thus, post-exercise LFF was compensated by increased motor unit discharge rates which could only partly be accounted for by the small decrease in motor unit recruitment threshold.

Effects of information processing speed on learning, memory, and executive functioning in people living with HIV/AIDS.

PubMed

Fellows, Robert P; Byrd, Desiree A; Morgello, Susan

2014-01-01

It is unclear whether or to what degree literacy, aging, and other neurologic abnormalities relate to cognitive deficits among people living with HIV/AIDS in the combined antiretroviral therapy (CART) era. The primary aim of this study was to simultaneously examine the association of age, HIV-associated motor abnormalities, major depressive disorder, and reading level with information processing speed, learning, memory, and executive functions, and to determine whether processing speed mediated any of the relationships between cognitive and noncognitive variables. Participants were 186 racially and ethnically diverse men and women living with HIV/AIDS who underwent comprehensive neurological, neuropsychological, and medical evaluations. Structural equation modeling was utilized to assess the extent to which information processing speed mediated the relationship between age, motor abnormalities, major depressive disorder, and reading level with other cognitive abilities. Age, motor dysfunction, reading level, and current major depressive disorder were all significantly associated with information processing speed. Information processing speed fully mediated the effects of age on learning, memory, and executive functioning and partially mediated the effect of major depressive disorder on learning and memory. The effect of motor dysfunction on learning and memory was fully mediated by processing speed. These findings provide support for information processing speed as a primary deficit, which may account, at least in part, for many of the other cognitive abnormalities recognized in complex HIV/AIDS populations. The association of age and information processing speed may account for HIV/aging synergies in the generation of CART-era cognitive abnormalities.

Minor neurological dysfunction in five year old very preterm children is associated with lower processing speed.

PubMed

Kurpershoek, Tinka; Potharst-Sirag, Eva S; Aarnoudse-Moens, Cornelieke S H; van Wassenaer-Leemhuis, Aleid G

2016-12-01

Minor neurological dysfunction (MND) is present in one quarter to one third of children born very preterm (VP). The more severe form, complex (c)-MND has been associated with learning disabilities, behavioural and motor problems. To study the association between c-MND and neurocognitive and motor disabilities at age five in VP children without CP. Ninety-four children born with gestational age<30weeks and/or a birth weight<1000g were assessed at five years corrected age. MND was classified according to Touwen. The Wechsler Preschool and Primary School Scale of Intelligence (WPPSI-III-NL) was used to measure intelligence. Simple reaction time, focused attention and visuomotor coordination were measured using the Amsterdam Neuropsychological Tasks, and working memory using a Digit Span Task. For motor skills the Movement Assessment Battery for children (M-ABC2) was used. Eighty-one percent was classified as 'normal' (no or simple (s-)-MND) and 19% as 'abnormal'(c-MND or mild CP). The abnormal group had a significantly lower processing speed quotient (PSQ), M-ABC percentile score and slower simple Reaction Time than the normal group. Verbal IQ, Performance IQ, working memory, focused attention and visuomotor coordination did not differ between groups. Exclusion of the mild CP cases (n=4) led to similar results. Five year old VP children with c-MND have lower PSQ, slower reaction time, and poorer motor skills, than those without c-MND. Neurological examination should include identification of MND to help identify children at risk for neurocognitive disabilities. Copyright © 2016. Published by Elsevier Ireland Ltd.

Pathophysiology of motor dysfunction in a childhood motor neuron disease caused by mutations in the riboflavin transporter.

PubMed

Menezes, Manoj P; Farrar, Michelle A; Webster, Richard; Antony, Jayne; O'Brien, Katherine; Ouvrier, Robert; Kiernan, Matthew C; Burns, Joshua; Vucic, Steve

2016-01-01

Brown-Vialetto-Van Laere (BVVL) syndrome is a progressive motor and sensory neuronopathy secondary to mutations in SLC52A2 encoding the riboflavin transporter type 2 (RFVT2). The phenotype is characterized by early childhood onset hearing loss and sensory ataxia followed by progressive upper limb weakness, optic atrophy, bulbar weakness and respiratory failure. To gain further insight into disease pathophysiology and response to riboflavin supplementation, the present study investigated whether axonal ion channel or membrane abnormalities were a feature of BVVL. Axonal excitability studies and clinical assessments were prospectively undertaken on six patients with BVVL secondary to riboflavin transporter deficiency type 2 (age range 10-21 years) at baseline and after 12 months of riboflavin (1000 mg daily) therapy. At baseline, depolarizing and hyperpolarizing threshold electrotonus was 'fanned out' and superexcitability was increased, while the resting current-threshold gradient and refractoriness were significantly reduced in BVVL patients when compared to controls. Mathematical modeling suggested that functional alterations of myelin underlay these findings with an increase in myelin permeability. Riboflavin therapy resulted in partial normalization of the axonal excitability findings, paralleled by maintenance of muscle strength. The present study established that abnormalities in myelin permeability at the paranode was a feature of BVVL and were partially normalized with riboflavin therapy. This study reveals a novel pathophysiological process for motor nerve dysfunction in BVVL. It also indicates that nerve excitability studies may be further developed in larger cohorts as a potential biomarker to identify treatment response for BVVL patients. Crown Copyright © 2015. Published by Elsevier Ireland Ltd. All rights reserved.

Discrete mitochondrial aberrations in the spinal cord of sporadic ALS patients.

PubMed

Delic, Vedad; Kurien, Crupa; Cruz, Josean; Zivkovic, Sandra; Barretta, Jennifer; Thomson, Avery; Hennessey, Daniel; Joseph, Jaheem; Ehrhart, Jared; Willing, Alison E; Bradshaw, Patrick; Garbuzova-Davis, Svitlana

2018-08-01

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease characterized by progressive motor neuron degeneration in the brain and spinal cord leading to muscle atrophy, paralysis, and death. Mitochondrial dysfunction is a major contributor to motor neuron degeneration associated with ALS progression. Mitochondrial abnormalities have been determined in spinal cords of animal disease models and ALS patients. However, molecular mechanisms leading to mitochondrial dysfunction in sporadic ALS (sALS) patients remain unclear. Also, segmental or regional variation in mitochondrial activity in the spinal cord has not been extensively examined in ALS. In our study, the activity of mitochondrial electron transport chain complex IV was examined in post-mortem gray and white matter of the cervical and lumbar spinal cords from male and female sALS patients and controls. Mitochondrial distribution and density in spinal cord motor neurons, lateral funiculus, and capillaries in gray and white matter were analyzed by immunohistochemistry. Results showed that complex IV activity was significantly decreased only in gray matter in both cervical and lumbar spinal cords from ALS patients. In ALS cervical and lumbar spinal cords, significantly increased mitochondrial density and altered distribution were observed in motor neurons, lateral funiculus, and cervical white matter capillaries. Discrete decreased complex IV activity in addition to changes in mitochondria distribution and density determined in the spinal cord in sALS patients are novel findings. These explicit mitochondrial defects in the spinal cord may contribute to ALS pathogenesis and should be considered in development of therapeutic approaches for this disease. © 2018 Wiley Periodicals, Inc.

Reduced Activity of AMP-Activated Protein Kinase Protects against Genetic Models of Motor Neuron Disease

PubMed Central

Lim, M. A.; Selak, M. A.; Xiang, Z.; Krainc, D.; Neve, R. L.; Kraemer, B. C.; Watts, J. L.

2012-01-01

A growing body of research indicates that amyotrophic lateral sclerosis (ALS) patients and mouse models of ALS exhibit metabolic dysfunction. A subpopulation of ALS patients possesses higher levels of resting energy expenditure and lower fat-free mass compared to healthy controls. Similarly, two mutant copper zinc superoxide dismutase 1 (mSOD1) mouse models of familial ALS possess a hypermetabolic phenotype. The pathophysiological relevance of the bioenergetic defects observed in ALS remains largely elusive. AMP-activated protein kinase (AMPK) is a key sensor of cellular energy status and thus might be activated in various models of ALS. Here, we report that AMPK activity is increased in spinal cord cultures expressing mSOD1, as well as in spinal cord lysates from mSOD1 mice. Reducing AMPK activity either pharmacologically or genetically prevents mSOD1-induced motor neuron death in vitro. To investigate the role of AMPK in vivo, we used Caenorhabditis elegans models of motor neuron disease. C. elegans engineered to express human mSOD1 (G85R) in neurons develops locomotor dysfunction and severe fecundity defects when compared to transgenic worms expressing human wild-type SOD1. Genetic reduction of aak-2, the ortholog of the AMPK α2 catalytic subunit in nematodes, improved locomotor behavior and fecundity in G85R animals. Similar observations were made with nematodes engineered to express mutant tat-activating regulatory (TAR) DNA-binding protein of 43 kDa molecular weight. Altogether, these data suggest that bioenergetic abnormalities are likely to be pathophysiologically relevant to motor neuron disease. PMID:22262909

Mountain Plains Learning Experience Guide: Electric Motor Repair.

ERIC Educational Resources Information Center

Ziller, T.

This Electric Motor Repair Course is designed to provide the student with practical information for winding, repairing, and troubleshooting alternating current and direct current motors, and controllers. The course is comprised of eight units: (1) Electric Motor Fundamentals, (2) Rewinding, (3) Split-phase Induction Motors, (4) Capacitor Motors,…

75 FR 28656 - New United Motor Manufacturing, Inc., Formerly a Joint Venture of General Motors Corporation, and...

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... Manufacturing, Inc., Formerly a Joint Venture of General Motors Corporation, and Toyota Motor Corporation, Including On- Site Leased Workers From Corestaff, ABM Janitorial, and Toyota Engineering and Manufacturing... joint venture of General Motors Corporation and Toyota Motor Corporation, including on-site leased...

75 FR 62424 - New United Motor Manufacturing, Inc. Formerly a Joint Venture of General Motors Corporation and...

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2010-08-06

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Characterization of motor units in behaving adult mice shows a wide primary range

PubMed Central

Ritter, Laura K.; Tresch, Matthew C.; Heckman, C. J.; Manuel, Marin

2014-01-01

The mouse is essential for genetic studies of motor function in both normal and pathological states. Thus it is important to consider whether the structure of motor output from the mouse is in fact analogous to that recorded in other animals. There is a striking difference in the basic electrical properties of mouse motoneurons compared with those in rats, cats, and humans. The firing evoked by injected currents produces a unique frequency-current (F-I) function that emphasizes recruitment of motor units at their maximum force. These F-I functions, however, were measured in anesthetized preparations that lacked two key components of normal synaptic input: high levels of synaptic noise and neuromodulatory inputs. Recent studies suggest that the alterations in the F-I function due to these two components are essential for recreating firing behavior of motor units in human subjects. In this study we provide the first data on firing patterns of motor units in the awake mouse, focusing on steady output in quiet stance. The resulting firing patterns did not match the predictions from the mouse F-I behaviors but instead revealed rate modulation across a remarkably wide range (10–60 Hz). The low end of the firing range may be due to changes in the F-I relation induced by synaptic noise and neuromodulatory inputs. The high end of the range may indicate that, unlike other species, quiet standing in the mouse involves recruitment of relatively fast-twitch motor units. PMID:24805075

Characterization of motor units in behaving adult mice shows a wide primary range.

PubMed

Ritter, Laura K; Tresch, Matthew C; Heckman, C J; Manuel, Marin; Tysseling, Vicki M

2014-08-01

The mouse is essential for genetic studies of motor function in both normal and pathological states. Thus it is important to consider whether the structure of motor output from the mouse is in fact analogous to that recorded in other animals. There is a striking difference in the basic electrical properties of mouse motoneurons compared with those in rats, cats, and humans. The firing evoked by injected currents produces a unique frequency-current (F-I) function that emphasizes recruitment of motor units at their maximum force. These F-I functions, however, were measured in anesthetized preparations that lacked two key components of normal synaptic input: high levels of synaptic noise and neuromodulatory inputs. Recent studies suggest that the alterations in the F-I function due to these two components are essential for recreating firing behavior of motor units in human subjects. In this study we provide the first data on firing patterns of motor units in the awake mouse, focusing on steady output in quiet stance. The resulting firing patterns did not match the predictions from the mouse F-I behaviors but instead revealed rate modulation across a remarkably wide range (10-60 Hz). The low end of the firing range may be due to changes in the F-I relation induced by synaptic noise and neuromodulatory inputs. The high end of the range may indicate that, unlike other species, quiet standing in the mouse involves recruitment of relatively fast-twitch motor units. Copyright © 2014 the American Physiological Society.

Minimal Brain Dysfunction Child: Some Clinical Manifestations, Definitions, Descriptions and Remediation Approaches.

ERIC Educational Resources Information Center

Stock, Claudette, Comp.

Remediation of learning disabilities is discussed and a table of teaching materials related to psychological and motor functions is provided. Guides on 11 behavioral manifestations and three specific learning disabilities furnish definitions and description as well as techniques for training and management. Behavioral manifestations considered…

Gilles de la Tourette Syndrome: A Case Study.

ERIC Educational Resources Information Center

Hallenberg, Harvey

1997-01-01

Describes a Montessori teacher's experience with a sufferer of Tourette's syndrome, a dysfunction characterized by motor and vocal tics. Studies the progress over a school year, including work on academic skills utilizing the Montessori method and behavior. Shares research, successes, and failures in trying to reach the child. (SD)

Raspberry supplementation alleviates age-related motor dysfunction in select populations

USDA-ARS?s Scientific Manuscript database

Age-related declines in balance, muscle strength and coordination often lead to a higher incidence of falling. Among older adults, falls are the leading cause of distress, pain, injury, loss of confidence, and ultimately, loss of independence and death. Previous studies in our laboratory have demons...

Virtual Reality Goes to War: A Brief Review of the Future of Military Behavioral Healthcare

DTIC Science & Technology

2011-05-07

functional skill training and motor rehabilitation with patients having central nervous system dysfunction (e.g., stroke, TBI, SCI, cerebral palsy ...Improvement in cerebral function with treatment of posttraumatic stress disorder. Annals of the New York Academy of Sciences (NYAS), 1208, 142–149. Schneider

Mental Health Services in the Pittsburgh Public Schools; 1967-1968.

ERIC Educational Resources Information Center

Richman, Vivien

The 1967-68 mental health services (MHS) program in the Pittsburgh public school system, number of children served, studies undertaken, and other staff activities are considered. A research study of perceptual-motor dysfunction among emotionally disturbed, educable mentally handicapped, and normal children, and two perceptual surveys developed for…

Gastrostomy placement favorably alters the natural history of growth failure and undernutrition in Rett syndrome

USDA-ARS?s Scientific Manuscript database

Growth failure and undernutrition complicate the clinical course of girls with Rett syndrome (RTT). These abnormalities are, in part, the consequence of oral motor dysfunction and inadequate dietary intake. Our objective was to determine if gastrostomy placement for nutritional therapy alters the na...

Neuroimmune interactions at different intestinal sites are related to abdominal pain symptoms in children with IBS

USDA-ARS?s Scientific Manuscript database

Neuroimmune interactions and inflammation have been proposed as factors involved in sensory-motor dysfunction and symptom generation in adult irritable bowel syndrome (IBS) patients. In children with IBS and healthy controls, we measured ileocolonic mast cell infiltration and fecal calprotectin and ...

Clinical and Imaging Heterogeneity of Polymicrogyria: A Study of 328 Patients

ERIC Educational Resources Information Center

Leventer, Richard J.; Jansen, Anna; Pilz, Daniela T.; Stoodley, Neil; Marini, Carla; Dubeau, Francois; Malone, Jodie; Mitchell, L. Anne; Mandelstam, Simone; Scheffer, Ingrid E.; Berkovic, Samuel F.; Andermann, Frederick; Andermann, Eva; Guerrini, Renzo; Dobyns, William B.

2010-01-01

Polymicrogyria is one of the most common malformations of cortical development and is associated with a variety of clinical sequelae including epilepsy, intellectual disability, motor dysfunction and speech disturbance. It has heterogeneous clinical manifestations and imaging patterns, yet large cohort data defining the clinical and imaging…

Children with behavioral problems and motor problems have a worse neurological condition than children with behavioral problems only.

PubMed

Peters, Lieke H J; Maathuis, Carel G B; Hadders-Algra, Mijna

2014-12-01

Some evidence suggests that children with specific behavioral problems are at risk for motor problems. It is unclear whether neurological condition plays a role in the propensity of children with behavioral problems to develop motor problems. To examine the relation between behavioral problems, motor performance and neurological condition in school-aged children. Cross-sectional study. 174 children (95 boys) receiving mainstream education and 106 children (82 boys) receiving special education aged 6 to 13 years (mean 9 y 7 m, SD 1 y 10 m). Behavior was assessed with questionnaires: the parental Child Behavior Checklist (CBCL) and Teacher's Report Form (TRF). Motor performance was assessed with the Movement Assessment Battery for Children (MABC). MABC-scores ≥5th percentile were considered as age-adequate and scores <5th percentile indicated definite motor problems. Neurological condition was assessed in terms of Minor Neurological Dysfunction (MND). The majority of specific behavioral problems were associated with definite motor problems, except somatic complaints and rule breaking behavior. Children with externalizing problems, according to the CBCL or TRF, and motor problems had more often MND than children with externalizing problems only. The same holds true for internalizing problems according to the CBCL. The present study demonstrated that various forms of behavioral problems were associated with motor problems. Especially children with motor and behavioral problems showed MND. Copyright © 2014 Elsevier Ltd. All rights reserved.

Early uneven ear input induces long-lasting differences in left-right motor function.

PubMed

Antoine, Michelle W; Zhu, Xiaoxia; Dieterich, Marianne; Brandt, Thomas; Vijayakumar, Sarath; McKeehan, Nicholas; Arezzo, Joseph C; Zukin, R Suzanne; Borkholder, David A; Jones, Sherri M; Frisina, Robert D; Hébert, Jean M

2018-03-01

How asymmetries in motor behavior become established normally or atypically in mammals remains unclear. An established model for motor asymmetry that is conserved across mammals can be obtained by experimentally inducing asymmetric striatal dopamine activity. However, the factors that can cause motor asymmetries in the absence of experimental manipulations to the brain remain unknown. Here, we show that mice with inner ear dysfunction display a robust left or right rotational preference, and this motor preference reflects an atypical asymmetry in cortico-striatal neurotransmission. By unilaterally targeting striatal activity with an antagonist of extracellular signal-regulated kinase (ERK), a downstream integrator of striatal neurotransmitter signaling, we can reverse or exaggerate rotational preference in these mice. By surgically biasing vestibular failure to one ear, we can dictate the direction of motor preference, illustrating the influence of uneven vestibular failure in establishing the outward asymmetries in motor preference. The inner ear-induced striatal asymmetries identified here intersect with non-ear-induced asymmetries previously linked to lateralized motor behavior across species and suggest that aspects of left-right brain function in mammals can be ontogenetically influenced by inner ear input. Consistent with inner ear input contributing to motor asymmetry, we also show that, in humans with normal ear function, the motor-dominant hemisphere, measured as handedness, is ipsilateral to the ear with weaker vestibular input.

Characteristic changes of motor unit activity in hip joint flexor muscles during voluntary isometric contraction during water immersion.

PubMed

Sugajima, Y; Mitarai, G; Koeda, M; Moritani, T

1996-06-01

The effect of whole body water immersion on the recruitment order of hip flexor motor units was investigated in 11 male subjects. Intramuscular spike potentials were recorded, with fine bipolar wire electrodes, from the iliopsoas, the sartorius, the rectus femoris and the tensor fasciae latae during voluntary isometric contraction while the subjects were standing erect with the hip on the test side flexed to 60 degrees and the knee flexed to 120 degrees . Data were analysed by measuring the recruitment threshold in slow ramp contraction and by a computer-aided amplitude-frequency histogram of the spike potentials during short sustained contraction. The motor units were classified as low-amplitude units if they delivered spike potentials of less than 0.5 mV and high-amplitude units if the spike potentials exceeded 0.5 mV. In the ramp experiments, exposure to water immersion gave rise to a sudden increase in the recruitment thresholds of the low-amplitude units in all muscles, while in the recruitment thresholds of the high-amplitude units, the alterations differed among the muscles. The thresholds in the rectus femoris and tensor fasciae latae increased in the same direction as those of the low-amplitude units, while those in the iliopsoas and sartorius decreased in the opposite direction. The amplitude-frequency histograms clearly indicated that these different alterations occurred in all subjects, without exception. We concluded that unloading induced by water immersion changed the recruitment order of motor units during isometric contraction in the iliopsoas and sartorius, facilitating the recruitment of their larger motor units.

Botulinum toxin injections for chronic sialorrhoea in children are effective regardless of the degree of neurological dysfunction: A single tertiary institution experience.

PubMed

Mahadevan, Murali; Gruber, Maayan; Bilish, Darin; Edwards, Kathryn; Davies-Payne, David; van der Meer, Graeme

2016-09-01

To determine the effectiveness of submandibular salivary gland Botulinum Toxin Type-A (BTX-A) injection in the treatment of drooling in children with varying degrees of neurological dysfunction. A retrospective review of pre- and post-procedure drooling frequency and severity scores of patients receiving BTX-A between January 2008 and January 2013. Stratification to different subgroups of neurological impairment was performed according to Gross Motor Function Classification System (GMFCS) score. Drooling severity was assessed using Thomas-Stonell and Greenberg symptom questionnaires administered at time of initial consultation and 3 months after treatment. 48 sets of BTX-A injections in 26 patients with an average age of 9.45 years (range 7 months-18 years) were included in the study. Marked improvement in drooling was seen in 60.4% of patients, a marginal or brief improvement was seen in 20.8% and there was no improvement in 18.8%. No adverse events were reported following any of the BTX-A injections. BTX-A was safe and effective in the eight patients with pre-existing swallowing dysfunction. Subsequent drooling surgery was performed in 15 (57.7%) of the cohort, all 15 patients responded to BTX-A injections. In patients with Cerebral Palsy, there was no correlation between the severity of the neurological dysfunction as measured by the Gross Motor Function Classification System (GMFCS) score and the response to BTX-A treatment. Injection of BTX-A to the submandibular glands of children with neurological disorders is a safe procedure and results in a reduction in drooling in the majority of patients. Children with severe neurological dysfunction respond to BTX-A injections as effectively as their less impaired peers and the degree of response does not appear to be associated with the severity of neurological disability. BTX-A injection is a good initial procedure when drooling surgery is being considered. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT XIX, LEARNING ABOUT CRANKING MOTORS.

ERIC Educational Resources Information Center

Human Engineering Inst., Cleveland, OH.

THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATING PRINCIPLES OF CRANKING MOTORS USED ON DIESEL POWERED EQUIPMENT, TOPICS ARE (1) CRANKING MOTORS. (2) MOTOR PINCIPLES, (3) CRANKING MOTOR CIRCUITS, (4) TYPES OF CRANKING MOTOR DRIVES, AND (5) CRANKING MOTOR SOLENOID CIRCUITS. THE MODULE CONSISTS OF A…

Adjustments in motor unit properties during fatiguing contractions after training.

PubMed

Vila-Chã, Carolina; Falla, Deborah; Correia, Miguel Velhote; Farina, Dario

2012-04-01

The objective of the study was to investigate the effect of strength and endurance training on muscle fiber membrane properties and discharge rates of low-threshold motor units of the vasti muscles during fatiguing contractions. Twenty-five sedentary healthy men (age (mean ± SD) = 26.3 ± 3.9 yr) were randomly assigned to one of three groups: strength training, endurance training, or a control group. Conventional endurance and strength training was performed 3 d·wk⁻¹, during a period of 6 wk. Motor unit conduction velocity and EMG amplitude of the vastus medialis obliquus and lateralis muscles and biceps femoris were measured during sustained isometric knee extensions at 10% and 30% of the maximum voluntary contraction before and immediately after training. After 6 wk of training, the reduction in motor unit conduction velocity during the sustained contractions at 30% of the maximum voluntary force occurred at slower rates compared with baseline (P < 0.05). However, the rate of decrease was lower after endurance training compared with strength training (P < 0.01). For all groups, motor unit discharge rates declined during the sustained contraction (P < 0.001), and their trend was not altered by training. In addition, the biceps femoris-vasti coactivation ratio declined after the endurance training. Short-term strength and endurance training induces alterations of the electrophysiological membrane properties of the muscle fiber. In particular, endurance training lowers the rate of decline of motor unit conduction velocity during sustained contractions more than strength training.

Reduced firing rates of high threshold motor units in response to eccentric overload.

PubMed

Balshaw, Tom G; Pahar, Madhu; Chesham, Ross; Macgregor, Lewis J; Hunter, Angus M

2017-01-01

Acute responses of motor units were investigated during submaximal voluntary isometric tasks following eccentric overload (EO) and constant load (CL) knee extension resistance exercise. Ten healthy resistance-trained participants performed four experimental test sessions separated by 5 days over a 20 day period. Two sessions involved constant load and the other two used eccentric overload. EO and CL used both sessions for different target knee eccentric extension phases; one at 2 sec and the other at 4 sec. Maximal voluntary contractions (MVC) and isometric trapezoid efforts for 10 sec at 70% MVC were completed before and after each intervention and decomposed electromyography was used to measure motor unit firing rate. The firing rate of later recruited, high-threshold motor units declined following the 2-sec EO but was maintained following 2sec CL (P < 0.05), whereas MUFR for all motor units were maintained for both loading types following 4-sec extension phases. MVC and rate of force development where maintained following both EO and CL and 2 and 4 sec phases. This study demonstrates a slower firing rate of high-threshold motor units following fast eccentric overload while MVC was maintained. This suggests that there was a neuromuscular stimulus without cost to the force-generating capacity of the knee extensors. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Respiration-related discharge of hyoglossus muscle motor units in the rat.

PubMed

Powell, Gregory L; Rice, Amber; Bennett-Cross, Seres J; Fregosi, Ralph F

2014-01-01

Although respiratory muscle motor units have been studied during natural breathing, simultaneous measures of muscle force have never been obtained. Tongue retractor muscles, such as the hyoglossus (HG), play an important role in swallowing, licking, chewing, breathing, and, in humans, speech. The HG is phasically recruited during the inspiratory phase of the respiratory cycle. Moreover, in urethane anesthetized rats the drive to the HG waxes and wanes spontaneously, providing a unique opportunity to study motor unit firing patterns as the muscle is driven naturally by the central pattern generator for breathing. We recorded tongue retraction force, the whole HG muscle EMG and the activity of 38 HG motor units in spontaneously breathing anesthetized rats under low-force and high-force conditions. Activity in all cases was confined to the inspiratory phase of the respiratory cycle. Changes in the EMG were correlated significantly with corresponding changes in force, with the change in EMG able to predict 53-68% of the force variation. Mean and peak motor unit firing rates were greater under high-force conditions, although the magnitude of discharge rate modulation varied widely across the population. Changes in mean and peak firing rates were significantly correlated with the corresponding changes in force, but the correlations were weak (r(2) = 0.27 and 0.25, respectively). These data indicate that, during spontaneous breathing, recruitment of HG motor units plays a critical role in the control of muscle force, with firing rate modulation playing an important but lesser role.

Robust and accurate decoding of motoneuron behavior and prediction of the resulting force output.

PubMed

Thompson, Christopher K; Negro, Francesco; Johnson, Michael D; Holmes, Matthew R; McPherson, Laura Miller; Powers, Randall K; Farina, Dario; Heckman, Charles J

2018-05-03

The spinal alpha motoneuron is the only cell in the human CNS whose discharge can be routinely recorded in humans. We have reengineered motor unit collection and decomposition approaches, originally developed in humans, to measure the neural drive to muscle and estimate muscle force generation in the decerebrate cat model. Experimental, computational, and predictive approaches are used to demonstrate the validity of this approach across a wide range of modes to activate the motor pool. The utility of this approach is shown through the ability to track individual motor units across trials, allowing for better predictions of muscle force than the electromyography signal, and providing insights in to the stereotypical discharge characteristics in response to synaptic activation of the motor pool. This approach now allows for a direct link between the intracellular data of single motoneurons, the discharge properties of motoneuron populations, and muscle force generation in the same preparation. The discharge of a spinal alpha motoneuron and the resulting contraction of its muscle fibers represents the functional quantum of the motor system. Recent advances in the recording and decomposition of the electromyographic signal allows for the identification of several tens of concurrently active motor units. These detailed population data provide the potential to achieve deep insights into the synaptic organization of motor commands. Yet most of our understanding of the synaptic input to motoneurons is derived from intracellular recordings in animal preparations. Thus, it is necessary to extend the new electrode and decomposition methods to recording of motor unit populations in these same preparations. To achieve this goal, we use high-density electrode arrays and decomposition techniques, analogous to those developed for humans, to record and decompose the activity of tens of concurrently active motor units in a hindlimb muscle in the decerebrate cat. Our results showed that the decomposition method in this animal preparation was highly accurate, with conventional two-source validation providing rates of agreement equal to or superior to those found in humans. Multidimensional reconstruction of the motor unit action potential provides the ability to accurately track the same motor unit across multiple contractions. Additionally, correlational analyses demonstrate that the composite spike train provides better estimates of whole muscle force than conventional estimates obtained from the electromyographic signal. Lastly, stark differences are observed between the modes of activation, in particular tendon vibration produced quantal interspike intervals at integer multiples of the vibration period. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Complex Dynamics in the Basal Ganglia: Health and Disease Beyond the Motor System.

PubMed

Andres, Daniela S; Darbin, Olivier

2018-01-01

The rate and oscillatory hypotheses are the two main current frameworks of basal ganglia pathophysiology. Both hypotheses have emerged from research on movement disorders sharing similar conceptualizations. These pathological conditions are classified either as hypokinetic or hyperkinetic, and the electrophysiological hallmarks of basal ganglia dysfunction are categorized as prokinetic or antikinetic. Although nonmotor symptoms, including neurobehavioral symptoms, are a key manifestation of basal ganglia dysfunction, they are uncommonly accounted for in these models. In patients with Parkinson's disease, the broad spectrum of motor symptoms and neurobehavioral symptoms challenges the concept that basal ganglia disorders can be classified into two categories. The profile of symptoms of basal ganglia dysfunction is best characterized by a breakdown of information processing, accompanied at an electrophysiological level by complex alterations of spiking activity from basal ganglia neurons. The authors argue that the dynamics of the basal ganglia circuit cannot be fully characterized by linear properties such as the firing rate or oscillatory activity. In fact, the neuronal spiking stream of the basal ganglia circuit is irregular but has temporal structure. In this context, entropy was introduced as a measure of probabilistic irregularity in the temporal organization of neuronal activity of the basal ganglia, giving place to the entropy hypothesis of basal ganglia pathology. Obtaining a quantitative characterization of irregularity of spike trains from basal ganglia neurons is key to elaborating a new framework of basal ganglia pathophysiology.

Investigation of the role of non-selective calcium channel blocker (flunarizine) on cerebral ischemic-reperfusion associated cognitive dysfunction in aged mice.

PubMed

Gulati, Puja; Muthuraman, Arunachalam; Kaur, Parneet

2015-04-01

The present study was designed to investigate the role of flunarizine (a non-selective calcium channel blocker) on cerebral ischemic-reperfusion associated cognitive dysfunction in aged mice. Bilateral carotid artery occlusion of 12min followed by reperfusion for 24h was given to induce cerebral injury in male Swiss mice. The assessment of learning & memory was performed by Morris water maze test; motor in-coordination was evaluated by rota rod, lateral push and inclined beam walking tests; cerebral infarct size was quantified by triphenyltetrazolium chloride staining. In addition, reduced glutathione (GSH), total calcium and acetylcholinesterase (AChE) activity were also estimated in aged brain tissue. Donepezil treated group served as a positive control in this study. Ischemia reperfusion (I/R) injury produced significant increase in cerebral infarct size. A significant loss of memory along with impairment of motor performance was also noted. Further, I/R injury also produced significant increase in levels of total calcium, AChE activity and decrease in GSH levels. Pretreatment of flunarizine significantly attenuated I/R induced infarct size, behavioral and biochemical changes. Hence, it may be concluded that, a non-selective calcium channel blocker can be useful in I/R associated cognitive dysfunction due to its anti-oxidant, anti-infarct and modulatory actions of neurotransmitters & calcium channels. Copyright © 2015 Elsevier Inc. All rights reserved.

Manifestations of Parkinson disease differ in association with REM sleep behavior disorder.

PubMed

Postuma, Ronald B; Gagnon, Jean-Francois; Vendette, Melanie; Charland, Katia; Montplaisir, Jacques

2008-09-15

REM sleep behavior disorder (RBD) is commonly associated with Parkinson disease (PD), but it is unclear whether this association has implications for disease manifestations. We evaluated 36 PD patients for the presence of RBD by polysomnography. Patients underwent an extensive evaluation by a movement disorders specialist blinded to polysomnography results. Severity of motor manifestations, autonomic, visual, psychiatric, and olfactory dysfunctions and quality of life (QOL) were assessed, and compared using regression analysis that adjusted for disease duration, age and sex. Severity of motor manifestations did not differ between groups. However, the presence of RBD in PD was strongly associated with symptoms and signs of orthostatic hypotension (systolic blood pressure lying to standing = -25.7 +/- 13.0 mmHg vs. -4.9 +/-14.1, P < 0.001); and orthostatic symptom prevalence = 71% vs. 27%, P = 0.0076). There was no association between RBD and other autonomic symptoms. Color vision was worse in patients with RBD, but olfactory dysfunction did not differ between groups. The prevalence of depression, hallucinations, paranoia, and impulse disorders did not differ between groups. Emotional functioning and general health QOL measures were lower in those with RBD, but there were no differences between groups on disease-specific indices or on measures of overall physical QOL. These findings suggest that the pathophysiology of RBD and nonmotor manifestations of PD, particularly autonomic dysfunction, are linked. (c) 2007 Movement Disorder Society.

Rational pharmacological approaches for cognitive dysfunction and depression in Parkinson's disease.

PubMed

Sandoval-Rincón, Maritza; Sáenz-Farret, Michel; Miguel-Puga, Adán; Micheli, Federico; Arias-Carrión, Oscar

2015-01-01

Parkinson's disease (PD) is not a single entity but rather a heterogeneous neurodegenerative disorder. The present study aims to conduct a critical systematic review of the literature to describe the main pharmacological strategies to treat cognitive dysfunction and major depressive disorder in PD patients. We performed a search of articles cited in PubMed from 2004 to 2014 using the following MeSH terms (Medical subject headings) "Parkinson disease"; "Delirium," "Dementia," "Amnestic," "Cognitive disorders," and "Parkinson disease"; "depression," "major depressive disorder," "drug therapy." We found a total of 71 studies related to pharmacological treatment in cognitive dysfunction and 279 studies for pharmacological treatment in major depressive disorder. After fulfillment of all the inclusion and exclusion criteria, 13 articles remained for cognitive dysfunction and 11 for major depressive disorder, which are presented and discussed in this study. Further research into non-motor symptoms of PD may provide insights into mechanisms of neurodegeneration, and provide better quality of life by using rational drugs.