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At least 73 records · Page 4Linked to original sources

PubMed2005

Real-time haptic-teleoperated robotic system for motor control analysis.

A versatile teleoperated robotic system was created as an assessment device for testing upper-extremity motor control adaptation using different control strategies. While many systems display output virtually on a computer monitor, this system was designed to output in three-dimensional physical space. The system accepts haptic force and torque input, and outputs robot end-effector displacements and rotations in three spatial dimensions. Benefits of this system include flexibility to conduct a variety of dissimilar tasks and reality of user feedback in physical space. Two separate experiments validated the teleoperated robotic system. The first experiment tested unimanual human motor control and the second tested bimanual motor control. This teleoperated robotic system can be used as an assessment device to study neuromuscular adaptability via a variety of control strategies providing a new and functional approach to human motor control analysis.

Arm↗

PubMed2005

fMRI reveals two distinct cerebral networks subserving speech motor control.

BACKGROUND: There are few data on the cerebral organization of motor aspects of speech production and the pathomechanisms of dysarthric deficits subsequent to brain lesions and diseases. The authors used fMRI to further examine the neural basis of speech motor control. METHODS AND RESULTS: In eight healthy volunteers, fMRI was performed during syllable repetitions synchronized to click trains (2 to 6 Hz; vs a passive listening task). Bilateral hemodynamic responses emerged at the level of the mesiofrontal and sensorimotor cortex, putamen/pallidum, thalamus, and cerebellum (two distinct activation spots at either side). In contrast, dorsolateral premotor cortex and anterior insula showed left-sided activation. Calculation of rate/response functions revealed a negative linear relationship between repetition frequency and blood oxygen level-dependent (BOLD) signal change within the striatum, whereas both cerebellar hemispheres exhibited a step-wise increase of activation at approximately 3 Hz. Analysis of the temporal dynamics of the BOLD effect found the various cortical and subcortical brain regions engaged in speech motor control to be organized into two separate networks (medial and dorsolateral premotor cortex, anterior insula, and superior cerebellum vs sensorimotor cortex, basal ganglia, and inferior cerebellum). CONCLUSION: These data provide evidence for two levels of speech motor control bound, most presumably, to motor preparation and execution processes. They also help to explain clinical observations such as an unimpaired or even accelerated speaking rate in Parkinson disease and slowed speech tempo, which does not fall below a rate of 3 Hz, in cerebellar disorders.

Adolescent↗

PubMedDate not supplied

The Cinderella of psychology: the neglect of motor control in the science of mental life and behavior.

One would expect psychology--the science of mental life and behavior--to place great emphasis on the means by which mental life is behaviorally expressed. Surprisingly, however, the study of how decisions are enacted--the focus of motor control research--has received little attention in psychology. This article documents the neglect and considers possible reasons for it. The hypotheses considered include three that are raised and then rejected: (a) no famous psychologists have studied motor control, (b) cognitive psychologists are mainly interested in uniquely human functions, and (c) motor control is simply too hard to study. Three other hypotheses are more viable: (d) cognitive psychologists have been more interested in epistemology than in action, (e) psychologists have disfavored motor control because overt responses were the only admissible measure in behaviorism, and (f) psychologists have felt that neuroscientists have the market cornered when it comes to motor control research. There are signs that motor control's Cinderella status is changing.

Cognition↗

PubMed2003

Rehabilitation of somatic sensation and related deficit of motor control in patients with pure sensory stroke.

OBJECTIVE: To assess the effectiveness of a rehabilitative training program for deficits in somatic sensation and motor control of the hand in patients with pure sensory stroke. DESIGN: Multiple baseline and before-after follow-up trial with behavioral analysis of single cases. SETTING: Rehabilitation unit of a university hospital in Italy. PARTICIPANTS: Four patients were studied: 2 had a unilateral lesion confined to the parietal lobe (patients 1, 2), and 2 had a unilateral lesion of the thalamus (patients 3, 4) that also lapped the posterior limb of the internal capsule. All 4 patients had chronic deficits in somatic sensation and motor control of the contralesional hand. INTERVENTION: Behavioral training consisting of exercises aimed at improving somatic sensation and motor control of the affected, contralesional hand. Thirty treatment sessions, each lasting 50 minutes, were performed. MAIN OUTCOME MEASURES: Somatic deficit was evaluated with 5 tests, and motor control deficit was assessed with 4 tests. One functional test estimated the influence of somatic deficit on daily activities. A visual analog scale (VAS) was also submitted to the patients' relatives to evaluate the amount of use of the affected arm in daily life activities. A baseline was obtained by recording each measure, except for the VAS, 4 times at the first evaluation session. Evaluation sessions were conducted before, after, and 6 months after the end of the experimental treatment. RESULTS: All patients showed a stable baseline in at least 8 of the outcome measures. Patients 1 and 2 significantly improved in 9 and 7 outcome measures, respectively. Patients 3 and 4 improved in 4 and 7 outcome measures, respectively. With the exception of case 3, all patients considerably increased their use of the affected arm during daily life. The improvement was generally stable over a 6-month period, suggesting that the treatment had a long-term effect. CONCLUSIONS: Results suggest the possible effectiveness of our training program for treating somatic and motor control deficits of the hand in patients with cortical or subcortical pure sensory stroke.

Adult↗

PubMed1998

Acute tolerance and reversal of the motor control effects of midazolam.

The purpose of this study was to determine whether acute tolerance develops to the motor control effects of the short-acting benzodiazepine, midazolam. Using a bolus and constant infusion scheme, 40 healthy adults received a 70-min intravenous infusion of either saline (n = 20) or 6.1 (SE = 0.2) mg midazolam (n = 20). Following the 70-min infusion period, half of the subjects in each group (n = 10) received a 25-min intravenous infusion of flumazenil (benzodiazepine antagonist); the remainder of the subjects (n = 10/group) received a 25-min infusion of saline. Drug administration during both infusion periods was double blind. Prior to the infusions, subjects were trained in a motor control assessment battery. Throughout both infusions, repeated motor control testing and blood sampling were performed. The initial (10 min) midazolam plasma concentration was 52.0 (SE = 2.2) ng/ml. Plasma midazolam concentration rose gradually to 60.7 (SE = 2.1) ng/ml at the end of the infusion (70 min). Midazolam initially impaired performance on the motor control tasks. However, performance improved in subjects receiving midazolam despite the gradual increase in midazolam concentrations. This suggests that the recovery of motor task performance may be attributable to the development of acute tolerance rather than to waning drug concentrations. Flumazenil immediately reversed midazolam's effects on the visual tracking task. However, there was little evidence for precipitation of muscle force rebound, which has been hypothesized to result from the same underlying mechanism that is responsible for acute tolerance development.

Adult↗

PubMed2006

Assessment of fine motor control in patients with occupation-related lateral epicondylitis.

Lateral epicondylitis (LE) is a common overuse injury related to a mechanical overload of the wrist extensors' origin; however, some patients also complain of clumsiness suggesting a possible motor control problem. The purpose of this study was to examine for differences in fine motor control ability between subjects with LE and matched control subjects. Subtests of the Purdue Pegboard Test (PPT) and the Complete Manual Dexterity Test (CMDT) were administered to 28 subjects with LE, and 28 age, gender, and hand dominance-matched control subjects. The LE group demonstrated a significant decrease in fine motor control ability on both measures, compared with the control group on both the PPT, F(1,52)=9.98, P=0.003, and the CMDT, F(1,52)=18.11, P=0.001. There appeared to be no effect for the length of time since injury. There were significant differences in fine motor control ability between individuals with LE and a matched control group for both measures used. These results suggest that tests of fine motor control should be considered in the assessment of clients with LE. The mechanism related to the deficit is unknown and warrants further research.

Adult↗

PubMed1988

Quantitative analyses of voluntary orofacial motor control in schizophrenia and tardive dyskinesia.

This paper reports the results of an investigation of voluntary control of lip, jaw, and tongue movements in schizophrenic patients with and without tardive dyskinesia. The aims of the study were to determine if voluntary orofacial motor control is disrupted in schizophrenia and to evaluate the relationship between voluntary motor control deficits and selected neurological and behavioral variables. Twenty-two schizophrenic patients and 13 normal control subjects were studied. Of the patients, 11 had moderate to severe TD. Analyses were made of performance on pursuit tracking tasks to evaluate differences between TD and non-TD patients and between medicated and currently unmedicated patients. The results indicated significant group differences in voluntary orofacial motor control. The finding that many non-TD patients exhibited voluntary motor dyscontrol suggests that this may represent a disorder independent of the involuntary dyskinesia. The findings indicated that the level of neuroleptic and/or antiparkinsonian medication was unrelated to the degree of voluntary motor control impairment. The results are discussed in terms of probable neurophysiological mechanisms underlying the motor control deficits in schizophrenia.

Adult↗

PubMedDate not supplied

Research on speech motor control and its disorders: a review and prospective.

This paper reviews issues in speech motor control and a class of communication disorders known as motor speech disorders. Speech motor control refers to the systems and strategies that regulate the production of speech, including the planning and preparation of movements (sometimes called motor programming) and the execution of movement plans to result in muscle contractions and structural displacements. Traditionally, speech motor control is distinguished from phonologic operations, but in some recent phonologic theories, there is a deliberate blurring of the boundaries between phonologic representation and motor functions. Moreover, there is continuing discussion in the literature as to whether a given motor speech disorder (especially apraxia of speech and stuttering) should be understood at the phonologic level, the motoric level, or both of these. The motor speech disorders considered here include: the dysarthrias, apraxia of speech, developmental apraxia of speech, developmental stuttering, acquired (neurogenic and psychogenic) stuttering, and cluttering.

Adolescent↗

PubMed1991

Observations on the motor control of brief teeth clenching in man.

Without artificial feedback control, maximum voluntary isometric contractions were performed for about 1 s by six subjects. Randomly selected surface electromyograms of the anterior temporalis and masseter muscles suggested that, in some cases, the motor control of the entire isometric contraction might have been preprogrammed through the phenomenon of anticipation. In the majority of cases, the control of the initial contraction phase might have been preprogrammed, followed by a phase of servo-controlled motor activity. As a functional basis for the servo-control of isometric force generation, it was suggested that compartmentalized 'extrafusal and intrafusal motor units' were recruited and decruited in an orderly manner, and periods of alpha-motor inhibition were interpreted as signs of switching from one control scheme to another, possibly via a transcortical loop.

Adult↗

PubMed2006

Prolonged cognitive planning time, elevated cognitive effort, and relationship to coordination and motor control following stroke.

Understanding cortical function can provide accurately targeted interventions after stroke. Initially, stroke survivors had prolonged cognitive planning time and elevated cognitive effort, highly correlated with motor control impairments. Exploratory results suggest that neurorehabilitation, accurately targeted to dyscoordination, weakness, and dysfunctional task component execution, can improve cognitive processes controlling motor function.

Adaptation, Physiological↗

PubMed2005

The effect of motor control exercise versus placebo in patients with chronic low back pain [ACTRN012605000262606].

BACKGROUND: While one in ten Australians suffer from chronic low back pain this condition remains extremely difficult to treat. Many contemporary treatments are of unknown value. One potentially useful therapy is the use of motor control exercise. This therapy has a biologically plausible effect, is readily available in primary care and it is of modest cost. However, to date, the efficacy of motor control exercise has not been established. METHODS: This paper describes the protocol for a clinical trial comparing the effects of motor control exercise versus placebo in the treatment of chronic non-specific low back pain. One hundred and fifty-four participants will be randomly allocated to receive an 8-week program of motor control exercise or placebo (detuned short wave and detuned ultrasound). Measures of outcomes will be obtained at follow-up appointments at 2, 6 and 12 months after randomisation. The primary outcomes are: pain, global perceived effect and patient-generated measure of disability at 2 months and recurrence at 12 months. DISCUSSION: This trial will be the first placebo-controlled trial of motor control exercise. The results will inform best practice for treating chronic low back pain and prevent its occurrence.

Chronic Disease↗

PubMedDate not supplied

Biocybernetic investigations of pursuit and posture motor control--a strategy for a detailed characterization of movement disorders in brain-damaged children.

By means of a biocybernetic approach the pursuit and posture motor control of brain-damaged children with spastic hemiparesis and disturbed motor coordination of mild extent were investigated. The postural motor control system was loaded by pseudostochastic binary torque sequences applied to the wrist. The dynamics of this system were characterized on the basis of the parameters forearm displacement as well as surface-EMG of M. Biceps and Triceps (calculations of weight functions). The pursuit motor control was analyzed by a pursuit tracking method. By this way the motor capacity for fine and rough motor coordination, motor rhythm, motor adaptation, the maximal speed of movements and motor reaction time could be tested. Considering these results a characterization of movement control on different levels of motor regulation was possible (dynamics of muscular, spinal, and supraspinal components of motor control).

Brain Damage, Chronic↗

PubMed2004

Visual function and fine-motor control in small-for-gestational age infants.

OBJECTIVE: To compare visual function and fine-motor control of full-term infants small-for-gestational age (SGA) and appropriate for gestational age (AGA), in the first three months. METHOD: We evaluated prospectively 31 infants in the 1st month; 33 in the 2nd and 34 infants in the 3rd month, categorized as full-term; birth weight less than 10th percentile for SGA and 25th to 90th percentile for the AGA group. Genetic syndromes, infections, multiple congenital malformations were excluded. The Bayley Scales of Infant Development-II were used, especially items related to visual function and to fine-motor control outcomes. RESULTS: The Motor Index Score (IS) was significantly lower in the SGA group in the 2nd month. The items "attempts to bring hands to mouth", in the 1st month and "reaches for suspended ring", in the 3rd month showed higher frequency in the SGA group. CONCLUSION: The Motor IS was lower in the 2nd month and items of fine-motor control in the 1st month and in the 3rd month showed higher frequency in the SGA group.

Attention↗

PubMed2006

Motor control and the management of musculoskeletal dysfunction.

This paper aims to develop understanding of three important motor control issues--feedforward mechanisms, cortical plasticity and task-specificity and assess the implications for musculoskeletal practice. A model of control for the reach-to-grasp movement illustrates how the central nervous system integrates sensorimotor processes to control complex movements. Feedforward mechanisms, an essential element of motor control, are altered in neurologically intact patients with chronic neck pain and low back pain. In healthy subjects, cortical mapping studies using transcranial magnetic stimulation have demonstrated that neural pathways adapt according to what and how much is practised. Neuroplasticity has also been demonstrated in a number of musculoskeletal conditions, where cortical maps are altered compared to normal. Behavioural and neurophysiological studies indicate that environmental and task constraints such as the goal of the task and an object's shape and size, are determinants of the motor schema for reaching and other movements. Consideration of motor control issues as well as signs and symptoms, may facilitate management of musculoskeletal conditions and improve outcome. Practice of entire everyday tasks at an early stage and systematic variation of the task is recommended. Training should be directed with the aim of re-educating feedforward mechanisms where necessary and the amount of practice should be sufficient to cause changes in cortical activity.

Feedback↗

PubMed1995

Differences in motor control in the bronchus and extrathoracic trachea.

The motor control of the bronchus and extrathoracic trachea was evaluated by continuously measuring bronchial diameter and tracheal muscle tension as well as phrenic nerve activity in decerebrated, paralyzed, artificially ventilated dogs. Spontaneous rhythmic changes in bronchial diameter and tracheal muscle tension occurred in phase with phrenic burst during mechanical ventilation and during apnea induced by disconnecting the ventilator. There was a small but consistent difference in the timing of their rhythmic activities; bronchial constriction started at mid-inspiration, whereas tracheal contraction began just prior to the end of inspiration. Both were active in the post-inspiratory phase. Both hypercapnia and apnea caused an enhanced rhythmic constriction of the bronchus, while evoking a tonic contraction of the trachea. Intermittent electric stimulation of the efferent vagus nerves revealed that repetitive stimulation with a short intermission was necessary to evoke a sustained constriction of the bronchus, and that the bronchus could maintain the sustained constriction only transiently. These results indicate that the motor control of the bronchus and extrathoracic trachea are distinct. The central nervous system may contribute to the difference in timing of the contraction between tracheal and bronchial smooth muscle. However, the difference in response to electric stimulation of the nervus vagus may be attributed to the peripheral neuromuscular system.

Animals↗

PubMed2006

Advances in graphonomics: studies on fine motor control, its development and disorders.

During the past 20 years graphonomic research has become a major contributor to the understanding of human movement science. Graphonomic research investigates the relationship between the planning and generation of fine motor tasks, in particular, handwriting and drawing. Scientists in this field are at the forefront of using new paradigms to investigate human movement. The 16 articles in this special issue of Human Movement Science show that the field of graphonomics makes an important contribution to the understanding of fine motor control, motor development, and movement disorders. Topics discussed include writer's cramp, multiple sclerosis, Parkinson's disease, schizophrenia, drug-induced parkinsonism, dopamine depletion, dysgraphia, motor development, developmental coordination disorder, caffeine, alertness, arousal, sleep deprivation, visual feedback transformation and suppression, eye-hand coordination, pen grip, pen pressure, movement fluency, bimanual interference, dominant versus non-dominant hand, tracing, freehand drawing, spiral drawing, reading, typewriting, and automatic segmentation.

Handwriting↗

PubMed2005

Anatomy of handedness and the laterality of seizure onset: surgical implications of new understandings in motor control.

OBJECTIVES: This article pursues another corollary of the anatomy of handedness, a code for the laterality of motor control. The latter indicates the absence of any motor communication from the minor (right, in the vast majority of population) to the major hemisphere (left, in the vast majority of right handers). It also indicates that all communications between the two hemispheres are excitatory in nature. This arrangement prohibits initiation of seizure within the minor and its propagation to the major hemisphere, via the callosum. METHODS: A comprehensive review of the literature is undertaken regarding theoretical and technical reasons for the failure of seizure surgery in subjects undergoing the same for intractable epilepsy. RESULTS: Whereas the laterality of motor control is heavily biased towards the left hemisphere (approximately 80%), the operation is performed equally on both hemispheres. Failures of surgery in some series were substantially higher among those who had undergone operations on the right hemisphere. Technical reasons for this are traced to the unreliability of tests commonly employed in securing laterality of seizure onset, which is the same as that of motor control. Accordingly, the failure rate of seizure surgery may equal the rate of false lateralization of the major hemisphere in these circumstances. CONCLUSION: Given the dichotomous anatomy of handedness, the most robust test for lateralizing the hemisphere of onset of seizure is that of determining the reaction times of two symmetrically located effectors, one on each side of the body. The side with the shorter reaction time will always be opposite to the major hemisphere. The difference between the two values is commensurate to the inter-hemispheric transfer time.

Brain↗

PubMed2003

Sophisticated spinal contributions to motor control.

The neural circuitry of the spinal cord is capable of solving some of the most complex problems in motor control. Therefore, spinal mechanisms are much more sophisticated than many neuroscientists give them credit for. A key issue in motor control is how sensory inputs direct and inform motor output,--that is, the sensorimotor process. Other major issues involve the actual control of the motor apparatus. In general, there are at least three basic requirements for motor control: the transformations that map information from sensory to motor coordinates, the specification of individual muscle activations to achieve a kinematic goal, and the control of multiple degrees of freedom. Here, we make the case that the vertebrate spinal cord has the capacity to solve each of these problems to a degree that is relevant for normal behavior.

Animals↗