scholarly journals Patterns of muscle activity for digital coarticulation

2013 ◽  
Vol 110 (1) ◽  
pp. 230-242 ◽  
Author(s):  
Sara A. Winges ◽  
Shinichi Furuya ◽  
Nathaniel J. Faber ◽  
Martha Flanders
Keyword(s):  
Time Course ◽  
Muscle Activation ◽  
Motor Pattern ◽  
Hand Movement ◽  
Time Frame ◽  
Pattern Generation ◽  
Emg Activity ◽  
Key Press ◽  
Basic Features ◽  
Piano Playing

Although piano playing is a highly skilled task, basic features of motor pattern generation may be shared across tasks involving fine movements, such as handling coins, fingering food, or using a touch screen. The scripted and sequential nature of piano playing offered the opportunity to quantify the neuromuscular basis of coarticulation, i.e., the manner in which the muscle activation for one sequential element is altered to facilitate production of the preceding and subsequent elements. Ten pianists were asked to play selected pieces with the right hand at a uniform tempo. Key-press times were recorded along with the electromyographic (EMG) activity from seven channels: thumb flexor and abductor muscles, a flexor for each finger, and the four-finger extensor muscle. For the thumb and index finger, principal components of EMG waveforms revealed highly consistent variations in the shape of the flexor bursts, depending on the type of sequence in which a particular central key press was embedded. For all digits, the duration of the central EMG burst scaled, along with slight variations across subjects in the duration of the interkeystroke intervals. Even within a narrow time frame (about 100 ms) centered on the central EMG burst, the exact balance of EMG amplitudes across multiple muscles depended on the nature of the preceding and subsequent key presses. This fails to support the idea of fixed burst patterns executed in sequential phases and instead provides evidence for neuromuscular coarticulation throughout the time course of a hand movement sequence.

scholarly journals Backward walking highlights gait asymmetries in children with cerebral palsy

2018 ◽  
Vol 119 (3) ◽  
pp. 1153-1165 ◽  
Author(s):  
Germana Cappellini ◽  
Francesca Sylos-Labini ◽  
Michael J. MacLellan ◽  
Annalisa Sacco ◽  
Daniela Morelli ◽  
...  
Keyword(s):  
Cerebral Palsy ◽  
Muscle Activation ◽  
Pattern Generation ◽  
Comprehensive Assessment ◽  
Emg Activity ◽  
Backward Walking ◽  
Spinal Circuitry ◽  
Children With Cerebral Palsy ◽  
Control Circuits ◽  
The Brain

To investigate how early injuries to developing motor regions of the brain affect different forms of gait, we compared the spatiotemporal locomotor patterns during forward (FW) and backward (BW) walking in children with cerebral palsy (CP). Bilateral gait kinematics and EMG activity of 11 pairs of leg muscles were recorded in 14 children with CP (9 diplegic, 5 hemiplegic; 3.0–11.1 yr) and 14 typically developing (TD) children (3.3–11.8 yr). During BW, children with CP showed a significant increase of gait asymmetry in foot trajectory characteristics and limb intersegmental coordination. Furthermore, gait asymmetries, which were not evident during FW in diplegic children, became evident during BW. Factorization of the EMG signals revealed a comparable structure of the motor output during FW and BW in all groups of children, but we found differences in the basic temporal activation patterns. Overall, the results are consistent with the idea that both forms of gait share pattern generation control circuits providing similar (though reversed) kinematic patterns. However, BW requires different muscle activation timings associated with muscle modules, highlighting subtle gait asymmetries in diplegic children, and thus provides a more comprehensive assessment of gait pathology in children with CP. The findings suggest that spatiotemporal asymmetry assessments during BW might reflect an impaired state and/or descending control of the spinal locomotor circuitry and can be used for diagnostic purposes and as complementary markers of gait recovery.NEW & NOTEWORTHY Early injuries to developing motor regions of the brain affect both forward progression and other forms of gait. In particular, backward walking highlights prominent gait asymmetries in children with hemiplegia and diplegia from cerebral palsy and can give a more comprehensive assessment of gait pathology. The observed spatiotemporal asymmetry assessments may reflect both impaired supraspinal control and impaired state of the spinal circuitry.

scholarly journals Flexibility of Motor Pattern Generation Across Stimulation Conditions by the Neonatal Rat Spinal Cord

2010 ◽  
Vol 103 (3) ◽  
pp. 1580-1590 ◽  
Author(s):  
David A. Klein ◽  
Angelica Patino ◽  
Matthew C. Tresch
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Muscle Activation ◽  
Motor Pattern ◽  
Pattern Generation ◽  
Neonatal Rat ◽  
Rat Spinal Cord ◽  
Afferent Pathways ◽  
Motor Pattern Generation ◽  
Stimulation Of

Previous studies have demonstrated that “locomotor-like” rhythmic patterns can be evoked in the isolated neonatal rat spinal cord by several means, including pharmacological neuromodulation and electrical stimulation of various pathways. Recent studies have used stimulation of afferent pathways to evoke rhythmic patterns, relying on synaptic activation of interneuronal systems rather than global imposition of neuromodulatory state by pharmacological agents. We use the in vitro neonatal rat spinal cord with attached hindlimb to examine the muscle activation patterns evoked by stimulation of these different pathways and evaluate whether stimulation of these pathways all evoke the same patterns. We find that the patterns evoked by bath application of serotonin (5-HT) and N-methyl-d-aspartic acid (NMDA) consisted of alternation between hip flexors and extensors and similar alternation was observed in the patterns evoked by electrical stimulation of the cauda equina (CE) or contralateral fifth lumbar (L5) dorsal nerve root. In contrast, the knee extensor/hip flexor rectus femoris (RF) and knee flexor/hip extensor semitendinosus (ST) were activated differentially across stimulation conditions. In 5-HT/NMDA patterns, RF was active in late flexion and ST in late extension. In CE patterns, these two muscles switched places with RF typically active in late extension and ST active in flexion. In L5 patterns, ST was activated in extension and RF was silent or weakly active during flexion. There were also systematic differences in the consistency of rhythms evoked by each stimulation method: patterns evoked by electrical stimulation of CE or L5 were less consistently modulated with the rhythm when compared with 5-HT/NMDA-evoked patterns. All differences were preserved following deafferentation, demonstrating that they reflect intrinsic properties of spinal systems. These results highlight the intrinsic flexibility of motor pattern generation by spinal motor circuitry which is present from birth and provides important information to many studies examining spinal pattern generating networks.

scholarly journals Locomotor patterns in cerebellar ataxia

2014 ◽  
Vol 112 (11) ◽  
pp. 2810-2821 ◽  
Author(s):  
G. Martino ◽  
Y. P. Ivanenko ◽  
M. Serrao ◽  
A. Ranavolo ◽  
A. d'Avella ◽  
...  
Keyword(s):  
Cerebellar Ataxia ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Rating Scale ◽  
Reaction Force ◽  
Neuromuscular Control ◽  
Pattern Generation ◽  
Heel Strike ◽  
Emg Activity ◽  
Foot Loading

Several studies have demonstrated how cerebellar ataxia (CA) affects gait, resulting in deficits in multijoint coordination and stability. Nevertheless, how lesions of cerebellum influence the locomotor muscle pattern generation is still unclear. To better understand the effects of CA on locomotor output, here we investigated the idiosyncratic features of the spatiotemporal structure of leg muscle activity and impairments in the biomechanics of CA gait. To this end, we recorded the electromyographic (EMG) activity of 12 unilateral lower limb muscles and analyzed kinematic and kinetic parameters of 19 ataxic patients and 20 age-matched healthy subjects during overground walking. Neuromuscular control of gait in CA was characterized by a considerable widening of EMG bursts and significant temporal shifts in the center of activity due to overall enhanced muscle activation between late swing and mid-stance. Patients also demonstrated significant changes in the intersegmental coordination, an abnormal transient in the vertical ground reaction force and instability of limb loading at heel strike. The observed abnormalities in EMG patterns and foot loading correlated with the severity of pathology [International Cooperative Ataxia Rating Scale (ICARS), a clinical ataxia scale] and the changes in the biomechanical output. The findings provide new insights into the physiological role of cerebellum in optimizing the duration of muscle activity bursts and the control of appropriate foot loading during locomotion.

II. Excitatory amino acid receptors in the brain-gut axis

2001 ◽  
Vol 280 (6) ◽  
pp. G1055-G1060 ◽  
Author(s):  
Pamela J. Hornby
Keyword(s):  
Metabotropic Glutamate Receptors ◽  
Excitatory Amino Acid ◽  
Motor Pattern ◽  
Pattern Generation ◽  
Gut Contents ◽  
Dorsal Vagal Complex ◽  
Gastric Accommodation ◽  
Metabotropic Glutamate ◽  
Therapeutic Benefits ◽  
The Brain

In the last decade, there has been a dramatic increase in academic and pharmaceutical interest in central integration of vago-vagal reflexes controlling the gastrointestinal tract. Associated with this, there have been substantial efforts to determine the receptor-mediated events in the dorsal vagal complex that underlie the physiological responses to distension or variations in the composition of the gut contents. Strong evidence supports the idea that glutamate is a transmitter in afferent vagal fibers conveying information from the gut to the brain, and the implications of this are discussed in this themes article. Furthermore, both ionotropic and metabotropic glutamate receptors mediate pre- and postsynaptic control of glutamate transmission related to several reflexes, including swallowing motor pattern generation, gastric accommodation, and emesis. The emphasis of this themes article is on the potential therapeutic benefits afforded by modulation of these receptors at the site of the dorsal vagal complex.

Time-course analysis of hepcidin, serum iron, and plasma cytokine levels in humans injected with LPS

Blood ◽  
2005 ◽  
Vol 106 (5) ◽  
pp. 1864-1866 ◽  
Author(s):  
Erwin Kemna ◽  
Peter Pickkers ◽  
Elizabeta Nemeth ◽  
Hans van der Hoeven ◽  
Dorine Swinkels
Keyword(s):  
Serum Iron ◽  
Time Course ◽  
Regulatory System ◽  
Peptide Hormone ◽  
Time Frame ◽  
Human Endotoxemia ◽  
Plasma Cytokines ◽  
Endotoxemia Model ◽  
Iron Parameters

Abstract Hepatic peptide hormone hepcidin is the key regulator of iron metabolism and the mediator of anemia of inflammation. Previous studies indicated that interleukin-6 (IL-6) mediates hepcidin increase and consequent hypoferremia during inflammation. Here we used an in vivo human endotoxemia model to analyze the effects of lipopolysaccharide (LPS) as a more upstream inflammation activator. The temporal associations between plasma cytokines, hepcidin levels, and serum iron parameters were studied in 10 healthy individuals after LPS injection. IL-6 was dramatically induced within 3 hours after injection, and urinary hepcidin peaked within 6 hours, followed by a significant decrease in serum iron. Serum prohepcidin showed no significant change within a 22-hour time frame. These in vivo human results confirm the importance of the IL-6-hepcidin axis in the development of hypoferremia in inflammation and highlight the rapid responsiveness of this iron regulatory system. (Blood. 2005;106: 1864-1866)

Principles of rhythmic motor pattern generation

1996 ◽  
Vol 76 (3) ◽  
pp. 687-717 ◽  
Author(s):  
E. Marder ◽  
R. L. Calabrese
Keyword(s):  
Motor Pattern ◽  
Pattern Generation ◽  
Rhythmic Movements ◽  
Motor Patterns ◽  
Nervous Systems ◽  
Cellular Processes ◽  
Rhythmic Motor ◽  
Computational Analyses ◽  
Motor Pattern Generation ◽  
Rhythmic Motor Pattern

Rhythmic movements are produced by central pattern-generating networks whose output is shaped by sensory and neuromodulatory inputs to allow the animal to adapt its movements to changing needs. This review discusses cellular, circuit, and computational analyses of the mechanisms underlying the generation of rhythmic movements in both invertebrate and vertebrate nervous systems. Attention is paid to exploring the mechanisms by which synaptic and cellular processes interact to play specific roles in shaping motor patterns and, consequently, movement.

Time-dependent progression of neurogenic lower urinary tract dysfunction after spinal cord injury in the mouse model

2021 ◽  
Author(s):  
Tetsuichi Saito ◽  
Daisuke Gotoh ◽  
Naoki Wada ◽  
Pradeep Tyagi ◽  
Tomonori Minagawa ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Time Course ◽  
Time Dependent ◽  
Lower Urinary Tract Dysfunction ◽  
Emg Activity ◽  
Mrna Levels ◽  
Mechanosensitive Channels ◽  
Reduction Time ◽  
Cord Injury

This study evaluated the time-course changes in bladder and external urinary sphincter (EUS) activity as well as the expression of mechanosensitive channels in lumbosacral dorsal root ganglia (DRG) after spinal cord injury (SCI). Female C57BL/6N mice in the SCI group underwent transection of the Th8/9 spinal cord. Spinal intact mice and SCI mice at 2, 4 and 6 weeks post SCI were evaluated by single-filling cystometry and EUS-electromyography (EMG). In another set of mice, the bladder and L6-S1 DRG were harvested for protein and mRNA analyses. In SCI mice, non-voiding contractions was confirmed at 2 weeks post-SCI, and did not increase over time to 6 weeks. In 2-weeks SCI mice, EUS-EMG measurements revealed detrusor-sphincter dyssynergia (DSD), but periodic EMG reductions during bladder contraction were hardly observed. At 4 weeks, SCI mice showed increases of EMG activity reduction time with increased voiding efficiency (VE). At 6 weeks, SCI mice exhibited a further increase in EMG reduction time. RT-PCR of L6-S1 DRG showed increased mRNA levels of TRPV1 and ASIC1-3 in SCI mice with a decrease of ASIC2-3 at 6 weeks compared to 4 weeks whereas Piezo2 showed a slow increase at 6 weeks. Protein assay showed the SCI-induced overexpression of bladder BDNF with a time-dependent decrease post SCI. These results indicate that detrusor overactivity is established in the early phase whereas DSD is completed later at 4 weeks with an improvement at 6 weeks post SCI, and that mechanosensitive channels may be involved in the time-dependent changes.

Development of an Apparatus for Bilateral Rhythmical Training of Arm Movement Via Linear and Elliptical Trajectories of Various Directions

2014 ◽  
Vol 8 (3) ◽  
Author(s):  
Zlatko Matjačić ◽  
Matjaž Zadravec ◽  
Jakob Oblak
Keyword(s):  
Muscle Activation ◽  
Arm Movement ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Arm Cycling ◽  
Arm Reaching ◽  
Direction Of Movement ◽  
Muscle Groups ◽  
Neurologically Intact

Clinical rehabilitation of individuals with various neurological disorders requires a significant number of movement repetitions in order to improve coordination and restoration of appropriate muscle activation patterns. Arm reaching movement is frequently practiced via motorized arm cycling ergometers where the trajectory of movement is circular thus providing means for practicing a single and rather nonfunctional set of muscle activation patterns, which is a significant limitation. We have developed a novel mechanism that in the combination with an existing arm ergometer device enables nine different movement modalities/trajectories ranging from purely circular trajectory to four elliptical and four linear trajectories where the direction of movement may be varied. The main objective of this study was to test a hypothesis stating that different movement modalities facilitate differences in muscle activation patterns as a result of varying shape and direction of movement. Muscle activation patterns in all movement modalities were assessed in a group of neurologically intact individuals in the form of recording the electromyographic (EMG) activity of four selected muscle groups of the shoulder and the elbow. Statistical analysis of the root mean square (RMS) values of resulting EMG signals have shown that muscle activation patterns corresponding to each of the nine movement modalities significantly differ in order to accommodate to variation of the trajectories shape and direction. Further, we assessed muscle activation patterns following the same protocol in a selected clinical case of hemiparesis. These results have shown the ability of the selected case subject to produce different muscle activation patterns as a response to different movement modalities which show some resemblance to those assessed in the group of neurologically intact individuals. The results of the study indicate that the developed device may significantly extend the scope of strength and coordination training in stroke rehabilitation which is in current clinical rehabilitation practice done through arm cycling.

Nonlinear viscosity of human wrist

1984 ◽  
Vol 52 (3) ◽  
pp. 553-569 ◽  
Author(s):  
C. C. Gielen ◽  
J. C. Houk
Keyword(s):  
Constant Velocity ◽  
Time Course ◽  
Fractional Power ◽  
Comparison Method ◽  
Mean Value ◽  
Emg Activity ◽  
Triggered Reactions ◽  
Nonlinear Viscosity ◽  
Flexor Muscles ◽  
Reflex Arc

Nonlinear viscous properties of stretch and unloading reflexes in the human wrist were examined using constant-velocity ramp stretches and releases in the range between 5 and 500 mm/s. Subjects were asked to oppose an initial flexor preload and were instructed not to intervene voluntarily when the changes in position were applied. Electromyographic (EMG) activity and net force exerted by the wrist were measured. Although subjects were instructed not to intervene to the applied stretches, even well-practiced subjects sometimes showed unintended triggered reactions, which character could be assisting or resisting. A trial comparison method was used to detect and eliminate responses contaminated by unintended reactions. Ramp stretches further loaded the preloaded flexor muscles. Responses of EMG and force increased steeply initially but after about 1-cm displacement, the slope of these responses decreased to a lower value and remained constant during the remainder of the 5-cm ramp. For higher stretch velocities, the magnitudes and slopes of the responses of EMG and force increased but less than proportionally with ramp velocity. Except for the initial transient, EMG in the loaded flexor muscles and force responses could be described by a product relationship between a linear position-related term and a low fractional power of velocity, after a correction was made for delays in the reflex arc. Mean value of the exponent in the power function of velocity was 0.3 for EMG and 0.17 for force. For higher preloads, incremental responses of force to constant-velocity stretches, plotted as a function of wrist position, shifted to higher values and the slope of increase of force with position became somewhat steeper. This upward shift of the force trace reflects a change of apparent threshold of the stretch reflex. Ramp releases shortened and unloaded the preloaded flexor muscles and stretched the initially inactive extensor muscles. Flexor EMG activity declined progressively with a time course that was independent of velocity. Extensor EMG response depended on preload. At high preloads, there was no activity except for some bursting at the highest velocities. At low preloads, EMG activity was initially absent but started part way through the ramp. The increase of activity was somewhat greater for higher ramp velocities. Force responses to shortening ramps depended on preload. At high preloads, force responses superimposed at all of the low velocities but fell to slightly lower forces at the higher velocities. At low preloads, force traces again superimposed for low velocities and at high velocities only during the initial part of the response.(ABSTRACT TRUNCATED AT 400 WORDS)

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