scholarly journals Express arm Responses Appear Bilaterally on Upper-limb Muscles in Arm Choice Reaching Task

2021 ◽  
Author(s):  
Sarah L Kearsley ◽  
Aaron L Cecala ◽  
Rebecca A Kozak ◽  
Brian D Corneil
Keyword(s):  
Upper Limb ◽  
Pectoralis Major Muscle ◽  
Electromyographic Activity ◽  
Visually Guided ◽  
Muscle Recruitment ◽  
Reaching Task ◽  
Reticulospinal Tract ◽  
Human Participants ◽  
The Right ◽  
Target Locations

When required, humans can generate very short latency reaches towards a visual target, like catching a phone falling off a desk. During such rapid reaches, express arm responses are the first wave of upper limb muscle recruitment, occurring within ~80-100 ms of target appearance. There is accumulating evidence that express arm responses arise from signaling along the tecto-reticulo-spinal tract, but the involvement of the reticulo-spinal tract has not been well-studied. Since the reticulospinal tract projects bilaterally, we studied whether express arm responses would be expressed bilaterally. Human participants (n = 14; 7 female) performed visually guided reaches in a modified emerging target paradigm where either arm could be used to intercept a target once it emerged below a barrier. We recorded electromyographic activity bilaterally from the pectoralis major muscle. Our analysis focused on target locations where participants reached with the right arm on some trials, and the left arm on others. In support of the involvement of the reticulospinal tract, the express arm response persisted bilaterally regardless of which arm reached to the target. While the latency of the express arm response was the same on the reaching vs non-reaching arm, the response magnitude was slightly larger on the reaching arm, in part due to anticipatory muscle recruitment related to arm choice. Our results support the involvement of the reticulo-spinal tract in mediating the express arm response, and we surmise that the increased magnitude on the arm chosen to move arises from convergence of cortically derived signals with the largely independent express arm response.

Reacquisition Deficits in Prism Adaptation After Muscimol Microinjection Into the Ventral Premotor Cortex of Monkeys

1999 ◽  
Vol 81 (4) ◽  
pp. 1927-1938 ◽  
Author(s):  
Kiyoshi Kurata ◽  
Eiji Hoshi
Keyword(s):  
Visual Field ◽  
Target Location ◽  
Premotor Cortex ◽  
Prism Adaptation ◽  
Horizontal Distance ◽  
Visually Guided ◽  
Dorsal Premotor Cortex ◽  
Reaching Task ◽  
Ventral Premotor Cortex ◽  
Target Locations

Reacquisition deficits in prism adaptation after muscimol microinjection into the ventral premotor cortex of monkeys. A small amount of muscimol (1 μl; concentration, 5 μg/μl) was injected into the ventral and dorsal premotor cortex areas (PMv and PMd, respectively) of monkeys, which then were required to perform a visually guided reaching task. For the task, the monkeys were required to reach for a target soon after it was presented on a screen. While performing the task, the monkeys’ eyes were covered with left 10°, right 10°, or no wedge prisms, for a block of 50–100 trials. Without the prisms, the monkeys reached the targets accurately. When the prisms were placed, the monkeys initially misreached the targets because the prisms displaced the visual field. Before the muscimol injection, the monkeys adapted to the prisms in 10–20 trials, judging from the horizontal distance between the target location and the point where the monkey touched the screen. After muscimol injection into the PMv, the monkeys lost the ability to readapt and touched the screen closer to the location of the targets as seen through the prisms. This deficit was observed at selective target locations, only when the targets were shifted contralaterally to the injected hemisphere. When muscimol was injected into the PMd, no such deficits were observed. There were no changes in the reaction and movement times induced by muscimol injections in either area. The results suggest that the PMv plays an important role in motor learning, specifically in recalibrating visual and motor coordinates.

scholarly journals High contrast, moving targets in an emerging target paradigm promote fast visuomotor responses during visually guided reaching

2021 ◽  
Author(s):  
Rebecca A. Kozak ◽  
Brian D. Corneil
Keyword(s):  
Superior Colliculus ◽  
Upper Limb ◽  
Human Subjects ◽  
Motor Output ◽  
High Contrast ◽  
Visually Guided ◽  
Muscle Recruitment ◽  
Moving Targets ◽  
Cortical Areas ◽  
Subcortical Pathway

AbstractHumans have a remarkable capacity to rapidly interact with the surrounding environment, often by transforming visual input into motor output on a moment-to-moment basis. But what visual features promote the shortest-latency reach responses? To address this question, we had human subjects perform visually guided reaches to moving targets varied by speed (experiment 1), or speed and contrast (experiment 2) in an emerging target paradigm, which has recently been shown to robustly elicit fast visuomotor responses. Our analysis focused on stimulus-locked responses (SLRs) on upper limb muscles. SLRs represent the first wave of muscle recruitment tied to visual target onset, appearing within <100 ms. Across 32 subjects studied in both experiments, 97% expressed SLRs in the emerging target paradigm. In comparison, 69% of these subjects expressed SLRs in a visually-guided reach paradigm. Within the emerging target paradigm, we found that target speed impacted SLR magnitude, whereas target contrast impacted SLR latency and magnitude. Thus, high contrast, faster-moving targets in the emerging target paradigm robustly recruited the circuitry mediating the most rapid visuomotor transformations for reaching, and such responses were associated with shorter latency RTs. Our results support the hypothesis that a subcortical pathway originating in the superior colliculus may be involved in the earliest wave of muscle recruitment following visual stimulus presentation. In scenarios requiring expedited responses, cortical areas may serve to prime this subcortical pathway, and elaborate subsequent phases of muscle recruitment following the SLR.Significance StatementHumans have a remarkable capacity, when necessary, to rapidly transform vision into action. But how does the brain do this? Here, by studying human subjects reaching to suddenly-appearing targets, we find that the earliest visually-guided actions are produced in response to high-contrast, moving targets. A millisecond-resolution examination of upper limb muscle recruitment shows that motor output can begin within less than 100 ms of target presentation. We surmise that this earliest recruitment arises from a phylogenetically-conserved brainstem circuit originating in the superior colliculus. Rather than being directly involved in the earliest phase of visuomotor actions, cortical areas may prime this brainstem circuit to produce initial muscle recruitment, and then elaborate subsequent phases of recruitment when time is of the essence.

Application of the GABA antagonist bicuculline to the premotor cortex reduces the ability to withhold reaching movements by well-trained monkeys in visually guided reaching task

1996 ◽  
Vol 75 (5) ◽  
pp. 2150-2156 ◽  
Author(s):  
T. Sawaguchi ◽  
I. Yamane ◽  
K. Kubota
Keyword(s):  
Premotor Cortex ◽  
Reaching Movements ◽  
Neuronal System ◽  
Gamma Aminobutyric Acid ◽  
Visually Guided ◽  
Reaching Task ◽  
Left Hand ◽  
Visually Guided Reaching ◽  
Gaba Antagonist ◽  
The Right

1. A gamma-aminobutyric acid (GABA) antagonist, bicuculline methiodide (BMI, 10 micrograms/microliters, 1 microliter), was locally injected into a total of 32 sites in the right premotor cortex (PM) of two rhesus monkeys that had been well-trained in a visually guided reaching task (VR) for approximately 3 yr. The monkey initiated the task by pressing a central hold lever with its left hand, and this was followed by waiting (1 s), warning (central green square on a computer monitor, 0.5 s), cue (right, upper, or left square), delay (2-5 s), and go (central green square changes to red, < 1.2 s) periods. In the go period, the monkey released the hold lever and reached out to one of three target levers (left, upper, or right) that had been indicated 2-5 s previously in the cue period. 2. At three sites in the dorsal part of the PM, after the local application of BMI, reaching movements of the left forelimb, which were not part of the trained-reaching, occurred 200-300 ms after the onset of a burst of neuronal activity at the BMI injection site. This induced-reaching, which was designated a "forced-reaching" movement, occurred while the monkeys were pressing the hold lever before the cue appeared-i.e., during the waiting or waiting period. No reaching occurred when the burst did not appear. Furthermore, trajectories and electromyograms of the forelimbs during the forced-reaching movements were similar to those in the trained-reaching movements in the VR task. 3. These results suggest that restricted sites in the dorsal PM of monkeys are involved in the initiation and/or execution of trained-reaching movements and that GABAergic inhibition at these sites normally suppresses this initiation/execution unless it is required. By relaxing GABAergic suppression, the dorsal PM might send a command to a neuronal system that is associated with trained reaching to recruit the system, thereby initiating and/or executing the trained reaching.

scholarly journals High contrast, moving targets in an emerging target paradigm promote fast visuomotor responses during visually guided reaching

2021 ◽  
Author(s):  
Rebecca A Kozak ◽  
Brian D Corneil
Keyword(s):  
Upper Limb ◽  
Fast Moving ◽  
Reaction Times ◽  
Short Latency ◽  
High Contrast ◽  
Visually Guided ◽  
Muscle Recruitment ◽  
Moving Targets ◽  
Large Magnitude ◽  
Limb Muscles

Humans have a remarkable capacity to rapidly interact with the surrounding environment, often by transforming visual input into motor output on a moment-to-moment basis. But what visual features promote rapid reaching? High contrast, fast-moving targets elicit strong responses in the superior colliculus (SC), a structure associated with express saccades and implicated in rapid electromyographic (EMG) responses on upper limb muscles. To test the influence of stimulus properties on rapid reaches, we had human subjects perform visually guided reaches to moving targets varied by speed (experiment 1) or speed and contrast (experiment 2), in an emerging target paradigm which has recently been shown to robustly elicit fast visuomotor responses. Our analysis focused on stimulus-locked responses (SLRs) on upper limb muscles. SLRs appear within <100 ms of target presentation, and as the first wave of muscle recruitment, they have been hypothesized to arise from the SC. Across 32 subjects studied in both experiments, 97% expressed SLRs in the emerging target paradigm, whereas only 69% expressed SLRs in an immediate response paradigm towards static targets. Faster moving targets (experiment 1) evoked large magnitude SLRs, while high contrast fast moving targets (experiment 2) evoked short latency, large magnitude SLRs. In some instances, SLR magnitude exceeded the magnitude of movement aligned activity. Both large magnitude and short latency SLRs were correlated with short latency reach reaction times. Our results support the hypothesis that, in scenarios requiring expedited responses, a subcortical pathway originating in the SC elicits the earliest wave of muscle recruitment, expediting reaction times.

scholarly journals An emerging target paradigm evokes fast visuomotor responses on human upper limb muscles

2020 ◽  
Author(s):  
Rebecca A. Kozak ◽  
Aaron L. Cecala ◽  
Brian D. Corneil
Keyword(s):  
Upper Limb ◽  
Visual Information ◽  
Pectoralis Major Muscle ◽  
Stimulus Presentation ◽  
Emg Activity ◽  
Visually Guided ◽  
Visuomotor Transformations ◽  
Limb Muscles ◽  
The Impact ◽  
Human Upper Limb

ABSTRACTTo reach towards a seen object, visual information has to be transformed into motor commands. Visual information such as the object’s colour, shape, and size is processed and integrated within numerous brain areas, then ultimately relayed to the motor periphery. In some instances we must react as fast as possible. These fast visuomotor transformations, and their underlying neurological substrates, are poorly understood in humans as they have lacked a reliable biomarker. Stimulus-locked responses (SLRs) are short latency (<100 ms) bursts of electromyographic (EMG) activity representing the first wave of muscle recruitment influenced by visual stimulus presentation. SLRs provide a quantifiable output of rapid visuomotor transformations, but SLRs have not been consistently observed in all subjects in past studies. Here we describe a new, behavioural paradigm featuring the sudden emergence of a moving target below an obstacle that consistently evokes robust SLRs. Human participants generated visually-guided reaches toward or away from the emerging target using a robotic manipulandum while surface electrodes recorded EMG activity from the pectoralis major muscle. In comparison to previous studies that investigated SLRs using static stimuli, the SLRs evoked with this emerging target paradigm were larger, evolved earlier, and were present in all participants. Reach reaction times (RTs) were also expedited in the emerging target paradigm. This paradigm affords numerous opportunities for modification that could permit systematic study of the impact of various sensory, cognitive, and motor manipulations on fast visuomotor responses. Overall, our results demonstrate that an emerging target paradigm is capable of consistently and robustly evoking activity within a fast visuomotor system.SUMMARYWe present a new behavioual paradigm that elicits robust fast visuomotor responses on human upper limb muscles during visually guided reaches.

scholarly journals Fatigue, induced via repetitive upper-limb motor tasks, influences trunk and shoulder kinematics during an upper limb reaching task in a virtual reality environment

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249403
Author(s):  
Frédérique Dupuis ◽  
Gisela Sole ◽  
Craig Wassinger ◽  
Mathieu Bielmann ◽  
Laurent J. Bouyer ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Upper Limb ◽  
Movement Speed ◽  
Electromyographic Activity ◽  
Virtual Reality Environment ◽  
Accuracy Improvement ◽  
Reaching Task ◽  
Fatigue Protocol ◽  
Time Interaction ◽  
Speed And Accuracy

Background Efficient shoulder movement depends on the ability of central nervous system to integrate sensory information and to create an appropriate motor command. Various daily encountered factors can potentially compromise the execution of the command, such as fatigue. This study explored how fatigue influences shoulder movements during upper limb reaching. Methods Forty healthy participants were randomly assigned to one of two groups: Control or Fatigue Group. All participants completed an upper limb reaching task at baseline and post-experimental, during which they reached four targets located at 90° of shoulder abduction, 90° external rotation at 90° abduction, 120° scaption, and 120° flexion in a virtual reality environment. Following the baseline phase, the Fatigue Group completed a shoulder fatigue protocol, while Controls took a 10-minute break. Thereafter, the reaching task was repeated. Upper limb kinematic (joint angles and excursions) and spatiotemporal (speed and accuracy) data were collected during the reaching task. Electromyographic activity of the anterior and middle deltoids were also collected to characterize fatigue. Two-way repeated-measures ANOVA were performed to determine the effects of Time, Group and of the interaction between these factors. Results The Fatigue group showed decreased mean median power frequency and increased electromyographic amplitudes of the anterior deltoid (p < 0.05) following the fatigue protocol. Less glenohumeral elevation, increased trunk flexion and rotation and sternoclavicular elevation were also observed in the Fatigue group (Group x Time interaction, p < 0.05). The Control group improved their movement speed and accuracy in post-experimental phase, while the Fatigue group showed a decrease of movement speed and no accuracy improvement (Group x Time interaction, p < 0.05). Conclusion In a fatigued state, changes in movement strategy were observed during the reaching task, including increased trunk and sternoclavicular movements and less glenohumeral movement. Performance was altered as shown by the lack of accuracy improvement over time and a decrease in movement speed in the Fatigue group.

A rare variation in the formation of the lower trunk of the brachial plexus its embryological basis and clinical importance - a case report

2012 ◽  
Vol 6 (4) ◽  
pp. 49-52
Author(s):  
N Satyanarayana ◽  
R Guha ◽  
P Sunitha ◽  
GN Reddy ◽  
G Praveen ◽  
...  
Keyword(s):  
Case Report ◽  
Brachial Plexus ◽  
Upper Limb ◽  
Clinical Importance ◽  
Medical Sciences ◽  
Nerve Roots ◽  
Rare Variation ◽  
Lower Trunk ◽  
Male Cadaver ◽  
The Right

Brachial plexus is the plexus of nerves, that supplies the upper limb.Variations in the branches of brachial plexus are common but variations in the roots and trunks are very rare. Here, we report one of the such rare variations in the formations of the lower trunk of the brachial plexus in the right upper limb of a male cadaver. In the present case the lower trunk was formed by the union of ventral rami of C7,C8 and T1 nerve roots. The middle trunk was absent. Upper trunk formation was normal. Journal of College of Medical Sciences-Nepal,2011,Vol-6,No-4, 49-52 DOI: http://dx.doi.org/10.3126/jcmsn.v6i4.6727

Força dos Músculos Rotadores do Ombro em Indivíduos Saudáveis/ Rotator Cuff Muscle Strength in Healthy Individuals

1970 ◽  
Vol 1 (1) ◽  
pp. 78-82
Author(s):  
Paulo José Oliveira Cortez ◽  
José Elias Tomazini ◽  
Mauro Gonçalves
Keyword(s):  
Rotator Cuff ◽  
Muscle Strength ◽  
Internal Rotation ◽  
Upper Limb ◽  
Statistical Difference ◽  
External Rotation ◽  
Healthy Individuals ◽  
Average Strength ◽  
Strength Tests ◽  
The Right

Introdução: A diminuição da capacidade de exercer esforços por parte dos músculos rotadores pode criar uma variedade de problemas. O conhecimento preciso do nível de força muscular de um indivíduo é importante, tanto para a avaliação da capacidade funcional ocupacional, como para uma apropriada prescrição de exercícios atléticos e de reabilitação. Percebe-se escassez de informação sobre as articulações do ombro, bem como os fatores envolvidos na força muscular dessa região. O objetivo deste estudo foi comparar a força gerada pelos músculos do manguito rotador entre o membro superior direito e o membro superior esquerdo em indivíduos saudáveis. Métodos: Participaram do estudo 22 sujeitos do sexo masculino, com idade de 18 e 19 anos, militares, saudáveis e sem história clínica de patologia ortopédica ou qualquer tipo de lesão no sistema musculoesquelético. Foram aplicados dois testes de força: Rotação Interna e Rotação Externa. Resultado : A força média de rotação interna no membro superior direito (MSD) foi maior que a força média de rotação interna no membro superior esquerdo (MSE) (p=0,723) e a força de rotação externa no MSD foi menor que a força média de rotação externa no MSE (p=0,788). Não houve diferença estatística na comparação dos valores de força de todos os testes de força isométrica. Conclusão: Para amostra estudada e metodologia utilizada na avaliação da força muscular, não houve diferença estatística na comparação da força gerada pelos músculos do manguito rotador do membro superior direito e do membro superior esquerdo.Rotator Cuff Muscle Strength in Healthy Individuals Introduction: Decreased ability to exert efforts by the rotator muscles can create a variety of problems. The precise knowledge of the level of muscular strength of an individual is important for both the functional capacity evaluation for occupational as an appropriate exercise prescription and rehabilitation of athletic. It is perceived scarcity of information on the shoulder joints as well as factors involved in muscle strength in this region. Objective: Develop a device for measuring the strength generated by the muscles of the upper limbs and the verification of efficiency and adaptability of this device through a comparative study of muscle strength in healthy subjects. Methods: The study included 22 male subjects, aged 18 and 19 years, military personnel, body mass between 57.7 and 93 kg (71.8 ± 9.45 kg) and height between 1.67 and 1.90 m (1.75 ± 0.06 m), healthy and without a history of orthopaedic disease or any kind of damage to the musculoskeletal system. Three strength tests were applied: Internal Rotation and External Rotation. For each type of effort three maximum voluntary contractions were required for 10 seconds, with an interval of 30 seconds between each contraction.  Results: Internal rotation in the right upper limb (RUL) was higher than the average strength of internal rotation in the left upper limb (LUL) (p = 0, 723) and the external rotation strength in RUL was lower than the average strength of external rotation in the LUL (p=0,788).  No statistical difference in comparing the strength values of all isometric strength tests. Conclusion: For sample and methodology used to assess muscle strength, there was no statistical difference in comparing the force generated by the muscles of the rotator cuff of the right and left upper limb.

scholarly journals The training schedule affects the stability, not the magnitude, of the interlimb transfer of learned dynamics

2013 ◽  
Vol 110 (4) ◽  
pp. 984-998 ◽  
Author(s):  
Wilsaan M. Joiner ◽  
Jordan B. Brayanov ◽  
Maurice A. Smith
Keyword(s):  
Short Duration ◽  
Dynamic Environment ◽  
Internal Representation ◽  
Motor Adaptation ◽  
Training Period ◽  
Visually Guided ◽  
Brief Training ◽  
Long Duration ◽  
The Stability ◽  
The Right

The way that a motor adaptation is trained, for example, the manner in which it is introduced or the duration of the training period, can influence its internal representation. However, recent studies examining the gradual versus abrupt introduction of a novel environment have produced conflicting results. Here we examined how these effects determine the effector specificity of motor adaptation during visually guided reaching. After adaptation to velocity-dependent dynamics in the right arm, we estimated the amount of adaptation transferred to the left arm, using error-clamp measurement trials to directly measure changes in learned dynamics. We found that a small but significant amount of generalization to the untrained arm occurs under three different training schedules: a short-duration (15 trials) abrupt presentation, a long-duration (160 trials) abrupt presentation, and a long-duration gradual presentation of the novel dynamic environment. Remarkably, we found essentially no difference between the amount of interlimb generalization when comparing these schedules, with 9–12% transfer of the trained adaptation for all three. However, the duration of training had a pronounced effect on the stability of the interlimb transfer: The transfer elicited from short-duration training decayed rapidly, whereas the transfer from both long-duration training schedules was considerably more persistent (<50% vs. >90% retention over the first 20 trials). These results indicate that the amount of interlimb transfer is similar for gradual versus abrupt training and that interlimb transfer of learned dynamics can occur after even a brief training period but longer training is required for an enduring effect.

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