scholarly journals Goal-dependent tuning of muscle spindle receptors during movement preparation

2021 ◽  
Vol 7 (9) ◽  
pp. eabe0401
Author(s):  
Stylianos Papaioannou ◽  
Michael Dimitriou
Keyword(s):  
Muscle Spindle ◽  
Muscle Force ◽  
Muscle Stiffness ◽  
Neural Mechanisms ◽  
Manual Task ◽  
Muscle Afferent ◽  
Preparatory Activity ◽  
Arm Muscles ◽  
Task Goals

Voluntary movements are believed to undergo preparation before they are executed. Preparatory activity can benefit reaction time and the quality of planned movements, but the neural mechanisms at work during preparation are unclear. For example, there are no overt changes in muscle force during preparation. Here, using an instructed-delay manual task, we demonstrate a decrease in human muscle afferent activity (primary spindles) when preparing to reach targets in directions associated with stretch of the spindle-bearing muscle. This goal-dependent modulation of proprioceptors began early after target onset but was markedly stronger at the latter parts of the preparatory period. Moreover, whole-arm perturbations during reach preparation revealed a modulation of stretch reflex gains (shoulder and upper arm muscles) that reflected the observed changes in spindle activity. We suggest that one function of central preparatory activity is to tune muscle stiffness according to task goals via the independent control of muscle spindle sensors.

scholarly journals Goal-dependent tuning of muscle spindle receptors during movement preparation

2020 ◽  
Author(s):  
Stylianos Papaioannou ◽  
Michael Dimitriou
Keyword(s):  
Muscle Spindle ◽  
Muscle Afferents ◽  
Human Muscle ◽  
Neural Mechanisms ◽  
Voluntary Movements ◽  
Movement Preparation ◽  
Manual Task ◽  
Spindle Bearing ◽  
Preparatory Activity ◽  
Arm Muscles

AbstractVoluntary movements are believed to be advantageously prepared before they are executed, but the neural mechanisms at work have been unclear. For example, there are no overt changes in skeletal muscle activity during movement preparation. Here, using a delayed-reach manual task, we demonstrate a decrease in the firing rate of human muscle afferents (primary spindles) when preparing stretch rather than shortening of the spindle-bearing muscle. This goal-dependent modulation of proprioceptors begun early after target onset but was markedly stronger at the latter parts of the preparatory period. In two additional experiments, whole-arm perturbations during reach preparation revealed a congruent modulation of stretch reflex gains of shoulder and upper arm muscles. Our study shows that movement preparation can involve sensory elements of the peripheral nervous system. We suggest that central preparatory activity can also reflect sensory control, and preparatory tuning of muscle spindle mechanoreceptors is a component of planned reaching movements.

Central modulation of the NO/cGMP pathway affects the MPOA-induced intracavernous pressure response

2001 ◽  
Vol 281 (1) ◽  
pp. R269-R278 ◽  
Author(s):  
Yoshikazu Sato ◽  
Weixin Zhao ◽  
George J. Christ
Keyword(s):  
Preoptic Area ◽  
Intrathecal Administration ◽  
Neural Mechanisms ◽  
Cavernous Nerve ◽  
Hypothalamic Nuclei ◽  
Organ Level ◽  
Intrathecal Drug Administration ◽  
Critical Aspects

Alterations in the nitric oxide (NO)/cGMP levels in hypothalamic nuclei, including the medial preoptic area (MPOA), regulate critical aspects of sexual behavior and penile reflexes. However, the effects of altered central nervous system (CNS) NO/cGMP levels at the end organ level, that is, on the magnitude/quality of the erection so achieved [intracavernous pressure (ICP) response], has yet to be evaluated. The goal of this report was to evaluate the effects of intrathecal administration of modulators of NO and cGMP levels on ICP responses to stimulation of the MPOA and cavernous nerve in rats in vivo. In all cases, intrathecal administration of compounds that increase and decrease cGMP and NO levels, respectively, was associated with corresponding increases and decreases in the MPOA-stimulated ICP response. Specifically, sodium nitroprusside (SNP), 8-bromo-cGMP, and sildenafil increased the MPOA-stimulated ICP response, whereas N ω-nitro-l-arginine methyl ester reduced it. None of the intrathecal treatments had detectable effects on blood pressure or the cavernous nerve-stimulated ICP response, although intravenous sildenafil increased the latter. These data clearly indicate that intrathecal drug administration affects central and not peripheral neural mechanisms and, moreover, documents that CNS NO/cGMP levels can affect erectile capacity per se (i.e., ICP) in the rat model.

scholarly journals Reward Processing under Chronic Pain from the Perspective of “Liking” and “Wanting”: A Narrative Review

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Xinhe Liu ◽  
Ning Wang ◽  
Lijia Gu ◽  
Jianyou Guo ◽  
Jinyan Wang ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Chronic Pain ◽  
Animal Studies ◽  
Daily Life ◽  
Reward Processing ◽  
Neural Mechanisms ◽  
Incentive Salience ◽  
Therapeutic Goals ◽  
Relieve Pain

The therapeutic goals of patients with chronic pain are not only to relieve pain but also to improve the quality of life. Chronic pain negatively affects various aspects of daily life, such as by decreasing the motivation to work and reward sensitivity, which may lead to difficulties in daily life or even unemployment. Human and animal studies have shown that chronic pain damages reward processing; the exploration of associated internal mechanisms may aid the development of treatments to repair this damage. Incentive salience theory, used widely to describe reward processing, divides this processing into “liking” (reward-induced hedonic sensory impact) and “wanting” (reward-induced motivation) components. It has been employed to explain pathological changes in reward processing induced by psychiatric disorders. In this review, we summarize the findings of studies of reward processing under chronic pain and examine the effects of chronic pain on “liking” and “wanting.” Evidence indicates that chronic pain compromises the “wanting” component of reward processing; we also discuss the neural mechanisms that may mediate this effect. We hope that this review aids the development of therapies to improve the quality of life of patients with chronic pain.

Contributions of motor-unit recruitment and rate modulation of compensation for muscle yielding

1982 ◽  
Vol 47 (5) ◽  
pp. 797-809 ◽  
Author(s):  
P. J. Cordo ◽  
W. Z. Rymer
Keyword(s):  
Motor Unit ◽  
Stretch Reflex ◽  
Muscle Force ◽  
Motor Units ◽  
Muscle Stiffness ◽  
Motor Unit Recruitment ◽  
Reflex Response ◽  
Rate Modulation ◽  
Stimulus Rate ◽  
Wide Range

1. Subdivided portions of the cut ventral root innervation of the soleus muscle were electrically stimulated in 14 anesthetized cats. The stimulus trains imposed on these nerves simulated the recruitment and rate-modulation patterns of single motor units recorded during stretch-reflex responses in decerebrate preparations. Each activation pattern was evaluated for its ability to prevent muscle yield. 2. Three basic stimulus patterns, recruitment, step increases in stimulus rate, and doublets were imposed during the course of ramp stretches applied over a wide range of velocities. The effect of each stimulus pattern on muscle force was compared to the force output recorded without stretch-related recruitment or rate modulation. 3. Motor-unit recruitment was found to be most effective in preventing yield during muscle stretch. Newly recruited motor units showed no evidence of yielding for some 250 ms following activation, at which time muscle stiffness declined slightly. This time-dependent resistance to yield was observed regardless of whether the onset of the neural stimulus closely preceded or followed stretch onset. 4. Step increases in stimulus rate arising shortly after stretch onset did not prevent the occurrence of yield at most stretch velocities, but did augment muscle stiffness later in the stretch. Doublets in the stimulus train were found to augment muscle stiffness only when they occurred in newly recruited motor units. 5. These results suggest that at low or moderate initial forces, the prevention of yield in lengthening, reflexively intact muscle results primarily from rapid motor-unit recruitment. To a lesser extent, the spring-like character of the stretch-reflex response also derives from step increases in firing rate of motor units active before stretch onset and doublets in units recruited during the course of stretch. Smooth rate increases appear to augment muscle force later in the course of the reflex response.

Physical activity diminishes aging-related decline of physical and cognitive performance

2014 ◽  
Vol 155 (21) ◽  
pp. 817-821 ◽  
Author(s):  
Péter Apor ◽  
László Babai
Keyword(s):  
Quality Of Life ◽  
Physical Activity ◽  
Life Expectancy ◽  
Aging Process ◽  
Muscle Force ◽  
Walking Speed ◽  
Prognostic Impact ◽  
Elderly Persons ◽  
The Impact

Aging-related decline of muscle force, walking speed, locomotor coordination, aerobic capacity and endurance exert prognostic impact on life expectancy. Proper use of training may diminish the aging process and it may improve the quality of life of elderly persons. This paper provides a brief summary on the impact of training on aging-related decline of physical and cognitive functions. Orv. Hetil., 2014, 155(21), 817–821.

scholarly journals Botulinum toxin injection causes hyper-reflexia and increased muscle stiffness of the triceps surae muscle in the rat

2016 ◽  
Vol 116 (6) ◽  
pp. 2615-2623 ◽  
Author(s):  
Jessica Pingel ◽  
Jacob Wienecke ◽  
Jakob Lorentzen ◽  
Jens Bo Nielsen
Keyword(s):  
Botulinum Toxin ◽  
Muscle Force ◽  
Botulinum Toxin Injection ◽  
Contralateral Side ◽  
Relative Increase ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Reflex Activity ◽  
Muscle Properties ◽  
Triceps Surae Muscle

Botulinum toxin is used with the intention of diminishing spasticity and reducing the risk of development of contractures. Here, we investigated changes in muscle stiffness caused by reflex activity or elastic muscle properties following botulinum toxin injection in the triceps surae muscle in rats. Forty-four rats received injection of botulinum toxin in the left triceps surae muscle. Control measurements were performed on the noninjected contralateral side in all rats. Acute experiments were performed, 1, 2, 4, and 8 wk following injection. The triceps surae muscle was dissected free, and the Achilles tendon was cut and attached to a muscle puller. The resistance of the muscle to stretches of different amplitudes and velocities was systematically investigated. Reflex-mediated torque was normalized to the maximal muscle force evoked by supramaximal stimulation of the tibial nerve. Botulinum toxin injection caused severe atrophy of the triceps surae muscle at all time points. The force generated by stretch reflex activity was also strongly diminished but not to the same extent as the maximal muscle force at 2 and 4 wk, signifying a relative reflex hyperexcitability. Passive muscle stiffness was unaltered at 1 wk but increased at 2, 4, and 8 wk ( P < 0.01). These data demonstrate that botulinum toxin causes a relative increase in reflex stiffness, which is likely caused by compensatory neuroplastic changes. The stiffness of elastic elements in the muscles also increased. The data are not consistent with the ideas that botulinum toxin is an efficient antispastic medication or that it may prevent development of contractures.

scholarly journals P141 The impact of exacerbations on muscle force, exercise capacity and quality of life in adults with cystic fibrosis

2018 ◽  
Vol 17 ◽  
pp. S99
Author(s):  
F. Pyl ◽  
E. Van Braeckel ◽  
F. De Baets ◽  
P. Calders ◽  
S. Bernaert ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Cystic Fibrosis ◽  
Exercise Capacity ◽  
Muscle Force ◽  
The Impact

scholarly journals Post-interval EEG activity is related to task-goals in temporal discrimination

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257378
Author(s):  
Fernanda Dantas Bueno ◽  
André Mascioli Cravo
Keyword(s):  
Brain Activity ◽  
Temporal Discrimination ◽  
Color Discrimination ◽  
Neural Mechanisms ◽  
Color Information ◽  
Eeg Activity ◽  
Linear Discriminant ◽  
Related Information ◽  
Human Participants ◽  
Task Goals

Studies investigating the neural mechanisms of time perception often measure brain activity while participants perform a temporal task. However, several of these studies are based exclusively on tasks in which time is relevant, making it hard to dissociate activity related to decisions about time from other task-related patterns. In the present study, human participants performed a temporal or color discrimination task of visual stimuli. Participants were informed which magnitude they would have to judge before or after presenting the two stimuli (S1 and S2) in different blocks. Our behavioral results showed, as expected, that performance was better when participants knew beforehand which magnitude they would judge. Electrophysiological data (EEG) was analysed using Linear Discriminant Contrasts (LDC) and a Representational Similarity Analysis (RSA) approach to investigate whether and when information about time and color was encoded. During the presentation of S1, we did not find consistent differences in EEG activity as a function of the task. On the other hand, during S2, we found that temporal and color information was encoded in a task-relevant manner. Taken together, our results suggest that task goals strongly modulate decision-related information in EEG activity.

scholarly journals Molecular development of muscle spindle and Golgi tendon organ sensory afferents revealed by single proprioceptor transcriptome analysis

2020 ◽  
Author(s):  
Katherine M. Oliver ◽  
Danny M. Florez-Paz ◽  
Tudor C. Badea ◽  
George Z. Mentis ◽  
Vilas Menon ◽  
...  
Keyword(s):  
Muscle Spindle ◽  
Developmental Stages ◽  
Motor Behavior ◽  
Molecular Signature ◽  
Golgi Tendon Organ ◽  
Sensory Afferents ◽  
Electrophysiological Recordings ◽  
Muscle Afferent ◽  
Tendon Organ

AbstractAnatomical and physiological analyses have long revealed differences between proprioceptive groups Ia, II, and Ib sensory neurons, yet the molecular correlates of these three muscle afferent subtypes remain unknown. We performed single cell RNA sequencing of genetically identified adult proprioceptors and, using unbiased bioinformatics approaches, detected five molecularly distinct neuronal clusters. Validation of cluster-specific transcripts in dorsal root ganglia (DRG) and skeletal muscle provides evidence these clusters correspond to functionally distinct muscle spindle (MS) or Golgi tendon organ (GTO) afferent proprioceptors. Remarkably, while we uncovered just one type of GTO afferents, four of the five clusters represent MS afferents, thus demonstrating a previously unappreciated diversity among these muscle proprioceptors. In vitro electrophysiological recordings reveal just two broadly distinct proprioceptor types, and suggest that the refinement of functional subtype diversity may occur along multiple axes of maturation. Lineage analysis between proprioceptor transcriptomes at different developmental stages show little or no correlation for transcripts that define adult MS or GTO afferents, supporting the idea that proprioceptor subtype identity emerges late in development. Together, our data provide the first comprehensive molecular signature for groups Ia and II MS afferents and group Ib GTO afferents, and offer new strategies for genetic interrogation of the role of these individual proprioceptor subtypes in regulating voluntary motor behavior.

scholarly journals New Challenges Resulting From the Loss of Function of Nav1.4 in Neuromuscular Diseases

2021 ◽  
Vol 12 ◽  
Author(s):  
Sophie Nicole ◽  
Philippe Lory
Keyword(s):  
Sodium Channel ◽  
Muscle Weakness ◽  
Muscle Force ◽  
Muscle Stiffness ◽  
Clinical Spectrum ◽  
Loss Of Function ◽  
Inherited Disorders ◽  
Paramyotonia Congenita ◽  
Α Subunit ◽  
Periodic Paralyses

The voltage-gated sodium channel Nav1.4 is a major actor in the excitability of skeletal myofibers, driving the muscle force in response to nerve stimulation. Supporting further this key role, mutations in SCN4A, the gene encoding the pore-forming α subunit of Nav1.4, are responsible for a clinical spectrum of human diseases ranging from muscle stiffness (sodium channel myotonia, SCM) to muscle weakness. For years, only dominantly-inherited diseases resulting from Nav1.4 gain of function (GoF) were known, i.e., non-dystrophic myotonia (delayed muscle relaxation due to myofiber hyperexcitability), paramyotonia congenita and hyperkalemic or hypokalemic periodic paralyses (episodic flaccid muscle weakness due to transient myofiber hypoexcitability). These last 5 years, SCN4A mutations inducing Nav1.4 loss of function (LoF) were identified as the cause of dominantly and recessively-inherited disorders with muscle weakness: periodic paralyses with hypokalemic attacks, congenital myasthenic syndromes and congenital myopathies. We propose to name this clinical spectrum sodium channel weakness (SCW) as the mirror of SCM. Nav1.4 LoF as a cause of permanent muscle weakness was quite unexpected as the Na+ current density in the sarcolemma is large, securing the ability to generate and propagate muscle action potentials. The properties of SCN4A LoF mutations are well documented at the channel level in cellular electrophysiological studies However, much less is known about the functional consequences of Nav1.4 LoF in skeletal myofibers with no available pertinent cell or animal models. Regarding the therapeutic issues for Nav1.4 channelopathies, former efforts were aimed at developing subtype-selective Nav channel antagonists to block myofiber hyperexcitability. Non-selective, Nav channel blockers are clinically efficient in SCM and paramyotonia congenita, whereas patient education and carbonic anhydrase inhibitors are helpful to prevent attacks in periodic paralyses. Developing therapeutic tools able to counteract Nav1.4 LoF in skeletal muscles is then a new challenge in the field of Nav channelopathies. Here, we review the current knowledge regarding Nav1.4 LoF and discuss the possible therapeutic strategies to be developed in order to improve muscle force in SCW.

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