scholarly journals Cutaneous reflex modulation and self-induced reflex attenuation in cerebellar patients

2015 ◽  
Vol 113 (3) ◽  
pp. 915-924 ◽  
Author(s):  
Wouter Hoogkamer ◽  
Frank Van Calenbergh ◽  
Stephan P. Swinnen ◽  
Jacques Duysens
Keyword(s):  
Muscle Activity ◽  
Neural Control ◽  
Biceps Femoris ◽  
Reflex Modulation ◽  
Neural Pathways ◽  
Common View ◽  
Control Subjects ◽  
Leg Muscles ◽  
Cutaneous Reflex ◽  
Healthy Control

Modulation of cutaneous reflexes is important in the neural control of walking, yet knowledge about underlying neural pathways is still incomplete. Recent studies have suggested that the cerebellum is involved. Here we evaluated the possible roles of the cerebellum in cutaneous reflex modulation and in attenuation of self-induced reflexes. First we checked whether leg muscle activity during walking was similar in patients with focal cerebellar lesions and in healthy control subjects. We then recorded cutaneous reflex activity in leg muscles during walking. Additionally, we compared reflexes after standard (computer triggered) stimuli with reflexes after self-induced stimuli for both groups. Biceps femoris and gastrocnemius medialis muscle activity was increased in the patient group compared with the control subjects, suggesting a coactivation strategy to reduce instability of gait. Cutaneous reflex modulation was similar between healthy control subjects and cerebellar patients, but the latter appeared less able to attenuate reflexes to self-induced stimuli. This suggests that the cerebellum is not primarily involved in cutaneous reflex modulation but that it could act in attenuation of self-induced reflex responses. The latter role in locomotion would be consistent with the common view that the cerebellum predicts sensory consequences of movement.

Forward and Backward Arm Cycling Are Regulated by Equivalent Neural Mechanisms

2005 ◽  
Vol 93 (1) ◽  
pp. 633-640 ◽  
Author(s):  
E. Paul Zehr ◽  
Sandra R. Hundza
Keyword(s):  
Neural Control ◽  
Arm Movement ◽  
Movement Direction ◽  
Reflex Modulation ◽  
Neural Activation ◽  
Cutaneous Reflexes ◽  
Leg Muscles ◽  
Cutaneous Reflex ◽  
Arm Cycling ◽  
Walking Activity

It was shown some time ago that cutaneous reflexes were phase-reversed when comparing forward and backward treadmill walking. Activity of central-pattern-generating networks (CPG) regulating neural activity for locomotion was suggested as a mechanism involved in this “program reversal.” We have been investigating the neural control of arm movements and the role for CPG mechanisms in regulating rhythmic arm cycling. The purpose of this study was to evaluate the pattern of muscle activity and reflex modulation when comparing forward and backward arm cycling. During rhythmic arm cycling (forward and backward), cutaneous reflexes were evoked with trains (5 × 1.0 ms pulses at 300 Hz) of electrical stimulation delivered to the superficial radial (SR) nerve at the wrist. Electromyographic (EMG) recordings were made bilaterally from muscles acting at the shoulder, elbow, and wrist. Analysis was conducted on specific sections of the movement cycle after phase-averaging contingent on the timing of stimulation in the movement cycle. EMG patterns for rhythmic arm cycling are similar during both forward and backward motion. Cutaneous reflex amplitudes were similarly modulated at both early and middle latency irrespective of arm cycling direction. That is, at similar phases in the movement cycle, responses of corresponding sign and amplitude were seen regardless of movement direction. The results are generally parallel to the observations seen in leg muscles after stimulation of cutaneous nerves in the foot during forward and backward walking and provide further evidence for CPG activity contributing to neural activation and reflex modulation during rhythmic arm movement.

scholarly journals Exploiting Interlimb Arm and Leg Connections for Walking Rehabilitation: A Training Intervention in Stroke

2016 ◽  
Vol 2016 ◽  
pp. 1-19 ◽  
Author(s):  
Taryn Klarner ◽  
Trevor S. Barss ◽  
Yao Sun ◽  
Chelsea Kaupp ◽  
Pamela M. Loadman ◽  
...  
Keyword(s):  
Neural Control ◽  
Cost Effective ◽  
Treadmill Walking ◽  
Reflex Modulation ◽  
Walking Ability ◽  
Cutaneous Reflex ◽  
Walking Rehabilitation ◽  
Increased Strength ◽  
Stride Duration ◽  
Cycling Training

Rhythmic arm and leg (A&L) movements share common elements of neural control. The extent to which A&L cycling training can lead to training adaptations which transfer to improved walking function remains untested. The purpose of this study was to test the efficacy of A&L cycling training as a modality to improve locomotor function after stroke. Nineteen chronic stroke (>six months) participants were recruited and performed 30 minutes of A&L cycling training three times a week for five weeks. Changes in walking function were assessed with (1) clinical tests; (2) strength during isometric contractions; and (3) treadmill walking performance and cutaneous reflex modulation. A multiple baseline (3 pretests) within-subject control design was used. Data show that A&L cycling training improved clinical walking status increased strength by ~25%, improved modulation of muscle activity by ~25%, increased range of motion by ~20%, decreased stride duration, increased frequency, and improved modulation of cutaneous reflexes during treadmill walking. On most variables, the majority of participants showed a significant improvement in walking ability. These results suggest that exploiting arm and leg connections with A&L cycling training, an accessible and cost-effective training modality, could be used to improve walking ability after stroke.

scholarly journals Leg Muscle Activity and Perception of Effort before and after Four Short Sessions of Submaximal Eccentric Cycling

2020 ◽  
Vol 17 (21) ◽  
pp. 7702
Author(s):  
Pierre Clos ◽  
Romuald Lepers
Keyword(s):  
Muscle Activity ◽  
Peak Power ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Peak Power Output ◽  
Leg Muscles ◽  
Perception Of Effort ◽  
Before And After ◽  
Power Outputs

Background: This study tested muscle activity (EMG) and perception of effort in eccentric (ECC) and concentric (CON) cycling before and after four sessions of both. Methods: Twelve volunteers naïve to ECC cycling attended the laboratory six times. On day 1, they performed a CON cycling peak power output (PPO) test. They then carried-out four sessions comprising two sets of 1 to 1.5-min cycling bouts at 5 intensities (30, 45, 60, 75, and 90% PPO) in ECC and CON cycling. On day 2 and day 6 (two weeks apart), EMG root mean square of the vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF), and soleus (SOL) muscles, was averaged from 15 to 30 s within each 1-min bout and perception of effort was asked after 45 s. Results: Before the four cycling sessions, while VL EMG was lower in ECC than CON cycling, most variables were not different. Afterwards, ECC cycling exhibited lower RF EMG at 75 and 90% PPO (all p < 0.02), lower VL and BF EMG at all exercise intensities (all p < 0.02), and inferior SOL EMG (all p < 0.04) except at 45% PPO (p = 0.07). Perception of effort was lower in ECC cycling at all exercise intensities (all p < 0.03) but 60% PPO (p = 0.11). Conclusions: After four short sessions of ECC cycling, the activity of four leg muscles and perception of effort became lower in ECC than in CON cycling at most of five power outputs, while they were similar before.

Trunk Muscle Coordination During Upward and Downward Reaching in Stroke Survivors

Motor Control ◽  
2016 ◽  
Vol 20 (1) ◽  
pp. 50-69 ◽  
Author(s):  
Geetanjali Gera ◽  
Kelsey E. McGlade ◽  
Darcy S. Reisman ◽  
John Peter Scholz
Keyword(s):  
Muscle Activity ◽  
Trunk Muscle ◽  
Uncontrolled Manifold ◽  
Stroke Survivors ◽  
Muscle Coordination ◽  
Trunk Motion ◽  
Control Subjects ◽  
Men 2 ◽  
Healthy Control ◽  
Muscle Modes

In this study, we investigated deficits in coordination of trunk muscle modes involved in the stabilization of the trunk’s trajectory for reaching upward and downward beyond functional arm length. Trunk muscle activity from 10 stroke survivors (8 men, 2 women; 64.1 ± 10.5 years old) and 9 healthy control subjects (7 men, 2 women; 59.3 ± 9.3 years old) was analyzed. Coordination of trunk muscle modes to stabilize the trunk trajectory was investigated using the uncontrolled manifold (UCM) analysis. The UCM analysis decomposes the variability of muscle modes into good and bad variability. The good variability does not affect the control of trunk motion, whereas the bad variability does. In stroke survivors, deficits in the ability to flexibly combine trunk muscle modes was associated with reduced ability to minimize those combinations of trunk muscle modes that led to an error in trunk trajectory (bad variability), and this had a greater effect on reaching upward. This reduced coordination of trunk muscle modes during reaching was correlated with a clinical measure of trunk impairment.

scholarly journals Neural control of rhythmic arm cycling after stroke

2012 ◽  
Vol 108 (3) ◽  
pp. 891-905 ◽  
Author(s):  
E. Paul Zehr ◽  
Pamela M. Loadman ◽  
Sandra R. Hundza
Keyword(s):  
Neural Control ◽  
Arm Movement ◽  
Constant Current ◽  
Cycle Phase ◽  
Emg Activity ◽  
Reflex Modulation ◽  
Cutaneous Reflexes ◽  
Cutaneous Reflex ◽  
Arm Cycling ◽  
Modulation Pattern

Disordered reflex activity and alterations in the neural control of walking have been observed after stroke. In addition to impairments in leg movement that affect locomotor ability after stroke, significant impairments are also seen in the arms. Altered neural control in the upper limb can often lead to altered tone and spasticity resulting in impaired coordination and flexion contractures. We sought to address the extent to which the neural control of movement is disordered after stroke by examining the modulation pattern of cutaneous reflexes in arm muscles during arm cycling. Twenty-five stroke participants who were at least 6 mo postinfarction and clinically stable, performed rhythmic arm cycling while cutaneous reflexes were evoked with trains (5 × 1.0-ms pulses at 300 Hz) of constant-current electrical stimulation to the superficial radial (SR) nerve at the wrist. Both the more (MA) and less affected (LA) arms were stimulated in separate trials. Bilateral electromyography (EMG) activity was recorded from muscles acting at the shoulder, elbow, and wrist. Analysis was conducted on averaged reflexes in 12 equidistant phases of the movement cycle. Phase-modulated cutaneous reflexes were present, but altered, in both MA and LA arms after stroke. Notably, the pattern was “blunted” in the MA arm in stroke compared with control participants. Differences between stroke and control were progressively more evident moving from shoulder to wrist. The results suggest that a reduced pattern of cutaneous reflex modulation persists during rhythmic arm movement after stroke. The overall implication of this result is that the putative spinal contributions to rhythmic human arm movement remain accessible after stroke, which has translational implications for rehabilitation.

Phase Reversal of Biomechanical Functions and Muscle Activity in Backward Pedaling

1999 ◽  
Vol 81 (2) ◽  
pp. 544-551 ◽  
Author(s):  
Lena H. Ting ◽  
Steven A. Kautz ◽  
David A. Brown ◽  
Felix E. Zajac
Keyword(s):  
Muscle Activity ◽  
Neural Control ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Specific Region ◽  
Medial Gastrocnemius ◽  
Phase Reversal ◽  
Control Scheme ◽  
Wide Range ◽  
Emg Patterns

Phase reversal of biomechanical functions and muscle activity in backward pedaling. Computer simulations of pedaling have shown that a wide range of pedaling tasks can be performed if each limb has the capability of executing six biomechanical functions, which are arranged into three pairs of alternating antagonistic functions. An Ext/Flex pair accelerates the limb into extension or flexion, a Plant/Dorsi pair accelerates the foot into plantarflexion or dorsiflexion, and an Ant/Post pair accelerates the foot anteriorly or posteriorly relative to the pelvis. Because each biomechanical function (i.e., Ext, Flex, Plant, Dorsi, Ant, or Post) contributes to crank propulsion during a specific region in the cycle, phasing of a muscle is hypothesized to be a consequence of its ability to contribute to one or more of the biomechanical functions. Analysis of electromyogram (EMG) patterns has shown that this biomechanical framework assists in the interpretation of muscle activity in healthy and hemiparetic subjects during forward pedaling. Simulations show that backward pedaling can be produced with a phase shift of 180° in the Ant/Post pair. No phase shifts in the Ext/Flex and Plant/Dorsi pairs are then necessary. To further test whether this simple yet biomechanically viable strategy may be used by the nervous system, EMGs from 7 muscles in 16 subjects were measured during backward as well as forward pedaling. As predicted, phasing in vastus medialis (VM), tibialis anterior (TA), medial gastrocnemius (MG), and soleus (SL) were unaffected by pedaling direction, with VM and SL contributing to Ext, MG to Plant, and TA to Dorsi. In contrast, phasing in biceps femoris (BF) and semimembranosus (SM) were affected by pedaling direction, as predicted, compatible with their contribution to the directionally sensitive Post function. Phasing of rectus femoris (RF) was also affected by pedaling direction; however, its ability to contribute to the directionally sensitive Ant function may only be expressed in forward pedaling. RF also contributed significantly to the directionally insensitive Ext function in both forward and backward pedaling. Other muscles also appear to have contributed to more than one function, which was especially evident in backward pedaling (i.e., BF, SM, MG, and TA to Flex). We conclude that the phasing of only the Ant and Post biomechanical functions are directionally sensitive. Further, we suggest that task-dependent modulation of the expression of the functions in the motor output provides this biomechanics-based neural control scheme with the capability to execute a variety of lower limb tasks, including walking.

GROUP SPECIFIC BEHAVIOR OF BIARTICULAR UPPER LEG MUSCLES EXEMPLIFIED BY SLEDGE

2011 ◽  
Vol 11 (05) ◽  
pp. 1085-1101 ◽  
Author(s):  
THOMAS ERTELT ◽  
REINHARD BLICKHAN
Keyword(s):  
Skeletal Muscles ◽  
Reaction Force ◽  
Biceps Femoris ◽  
Neural Pathways ◽  
Muscle Coordination ◽  
Specific Behavior ◽  
Contact Phase ◽  
Leg Muscles ◽  
Essential Parameter ◽  
Coupling Processes

The biarticular skeletal muscles represent a much considered topic in current research. Concerning these muscles, not only Lombard's paradox is of special interest. Some authors refer to their energy-transferring function and others have observed an increase of activity in M. biceps femoris after a special training. By means of so-called sledge jumps, we have experimentally examined the behavior of M. biceps femoris for two groups, jumpers and non-jumpers, whose task was to push the sledge with different loads and different speeds. The results clearly show a specific behavior of the muscles for each group — which seems to affect the muscle coordination and has crucial influence on the shape of the ground reaction force. Due to nearly equal kinematic conditions, Lombard's paradox could apply for both groups. However, the amount of training seems to be an essential parameter. The jumpers activate the M. biceps femoris during the entire contact phase and during the shortening as well as the stretching of the leg. Thus the force shape becomes smoother and shows fewer fluctuations. Despite positive geometrical conditions, not all subjects use this muscle from the beginning of the movement. In this context, neural pathways, inhibitions or coupling processes are decisive factors. All that indicates that the controlling of the muscle can only be achieved by an appropriate training.

Enhancement of Platelet Sensitivity to ADP-Aggregation by Isometric Exercise in Arteriosclerotic Patients and its Prevention

1977 ◽  
Vol 37 (02) ◽  
pp. 329-338 ◽  
Author(s):  
Tadahiro Sano ◽  
Takeshi Motomiya ◽  
Hiroh Yamazaki ◽  
Takio Shimamoto
Keyword(s):  
Cyclic Amp ◽  
Mechanical Stress ◽  
Optical Density ◽  
Platelet Function ◽  
Isometric Exercise ◽  
Phosphodiesterase Inhibitor ◽  
New Method ◽  
Platelet Aggregability ◽  
Control Subjects ◽  
Healthy Control

SummaryA new method for assessment of platelet sensitivity to ADP-aggregation was devised. Its reproducibility and the correlations between the values obtained by this method, the optical density (O. D.) method, and the screen filtration pressure (SFP) method were assessed. In summary, this method may be said to have three main points:1. It can be performed without centrifugation, avoiding mechanical stress to platelets, using only 0.8 ml. of blood and inexpensive equipment.2. It may reflect different aspects of platelet function from the O. D. method and the SFP method, despite the positive significant correlations between the values obtained by these three methods.3. It was proved to be highly reproducible and is thought to be useful clinically.By using this method, the effect of sustained isometric exercise by handgripping on platelet aggregability was assessed in coronary sclerotic and cerebral arteriosclerotic patients on placebo and EG-626, a newly synthesized cyclic AMP phosphodiesterase inhibitor. On placebo, an enhancement of platelet sensitivity was observed after isometric exercise in coronary and cerebral arteriosclerotic patients but not in healthy control subjects. The enhancement was prevented by pretreatment of EG-626, administered orally 1.5 hours prior to exercise.

Some Cytokines Levels (IL-6 and IL-10) in Sera Patients with Cutaneous Leismanasis in Nassiriya Province

2020 ◽  
pp. 4-6
Keyword(s):  
Serum Level ◽  
Immune Status ◽  
Pure Science ◽  
Control Subjects ◽  
Significant Difference ◽  
Healthy Control

The present study was carried out in the Labs of collage of education for pure science, during period from January 2017 to endDecember of the same year. The immune status investigates for CLpatients by measuring the levels of cytokines (IL6and IL10) in sera using a technique enzyme-linked immune Sorbent adsorptive (ELISA). The study included 120 subjects with (60 CLpatientsL.majar and 60 CLpatients L. tropica with and (30) were healthy control. Increased mean Serum level of IL6 was in the observed in the total patients as compared to control Subjects (224.53pg/ml,70.70pg/ml), the result indicate there was significant difference at (p<0.05) ,such observation was consistent in the patient infected with L.majar and L. tropica (104 .90 pg/ml and 112.78 pg/ml) respectively. The results of the IL10 showed significant difference at (p<0.05)increased of mean Serum level in the total CL patients as compared to control Subjects(226.90 pg/ml 46.77pg/ml,).Ahighly significant difference at (p<0.05) increased observed in patients group infected with L.majar and followed by patients group infected L. tropica (112.78pg/ml and 114.12pg/ml) respectively.These results revealed that the excessive presence of cytokines might play a role in CL patients.

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