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Monosynaptic reflex

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https://www.readbyqxmd.com/read/29895879/does-trans-spinal-direct-current-stimulation-modulate-the-hoffmann-reflexes-of-healthy-individuals-a-systematic-review-and-meta-analysisc
#1
REVIEW
Plínio Luna Albuquerque, Thyciane Mendonça, Mayara Campêlo, Lívia Shirahige, Kátia Monte-Silva
STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVES: To summarize the available evidence regarding the effects of trans-spinal direct current stimulation (tsDCS) on spinal monosynaptic circuit excitability in healthy individuals. SETTING: Applied Neuroscience Laboratory, Brazil. METHODS: Abstract screening was performed independently by two authors for studies found in the following databases: PubMed, CINAHL, PsycINFO, Web of Science, and LILACS...
June 12, 2018: Spinal Cord
https://www.readbyqxmd.com/read/29809047/task-dependent-modulation-of-spinal-and-transcortical-stretch-reflexes-linked-to-motor-learning-rate
#2
Michael Dimitriou
It is generally believed that task-dependent control of body configuration ("posture") is achieved by adjusting voluntary motor activity and transcortical "long-latency" reflexes. Spinal monosynaptic circuits are thought not to be engaged in such task-level control. Similarly, being in a state of motor learning has been strongly associated only with an upregulation of feedback responses at transcortical latencies and beyond. In two separate experiments, the current study examined the task-dependent modulation of stretch reflexes by perturbing the hand of human subjects while they were waiting for a "Go" signal to move at the different stages of a classic kinematic learning task (visuomotor rotation)...
June 2018: Behavioral Neuroscience
https://www.readbyqxmd.com/read/29679107/oligosynaptic-inhibition-mediated-by-group-ia-afferents-from-flexor-digitorum-superficialis-to-wrist-flexors-in-humans
#3
Mitsuhiro Nito, Wataru Hashizume, Manabu Jimenji, Katsuhiko Suzuki, Toshiaki Sato, Hiromi Fujii, Takuji Miyasaka, Masaomi Shindo, Akira Naito
Effects of low-threshold afferents from the flexor digitorum superficialis (FDS) to the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU) and extensor carpi ulnaris (ECU) motoneurons were examined using a post-stimulus time-histogram (PSTH) and electromyogram-averaging (EMG-A) methods in seven healthy human subjects. Electrical conditioning stimulation to the median nerve branch innervating FDS with the intensity immediately below the motor threshold was delivered. In the PSTH study, the stimulation produced a trough (inhibition) in 19/44 (43%) of FCR and 17/41 (41%) of FCU motor units...
April 20, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/29604384/allopregnanolone-effects-on-transmission-in-the-brain-stem-solitary-tract-nucleus-nts
#4
Sojin Kim, Sung-Moon Kim, Bermseok Oh, Jihoon Tak, Eunhee Yang, Young-Ho Jin
During pregnancy, the progesterone metabolite, allopregnanolone (ALLO), becomes elevated and has been associated with altered levels within the CNS and resulting changes in GABAA receptor function. Pregnant animals poorly compensate reflexes for a decrease in blood pressure during hemorrhage. Previous works suggested that ALLO decreases baroreflex responses by central actions, however, the underlying mechanisms are poorly understood. In this study, we tested ALLO actions on visceral afferent synaptic transmission at second-order neurons within medial portions of the nucleus tractus solitarius (NTS) using hindbrain slices from non-pregnant female rats...
May 21, 2018: Neuroscience
https://www.readbyqxmd.com/read/29526514/facilitation-of-antagonist-motor-output-through-short-latency-sensory-pathways-during-postnatal-development-in-the-mouse
#5
Patrick M Sonner, David R Ladle
Reciprocal inhibition of motor neurons via Ia inhibitory interneurons recruited by stimulation of proprioceptive afferents supplying antagonist muscles has been well described. Changes in the efficacy of inhibition, and sometimes even a switch from inhibition to facilitation, have been reported in the literature after disruption of descending pathways. We sought to test whether such facilitation could be expressed in normal animals by evaluating the presence of facilitation in acute preparations from uninjured animals...
May 1, 2018: Neuroscience Letters
https://www.readbyqxmd.com/read/29230172/-sensor-motor-maps-for-describing-linear-reflex-composition-in-hopping
#6
Christian Schumacher, André Seyfarth
In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular model that describes hopping movements. In this model, we consider the influence of proprioceptive length (LFB), velocity (VFB) and force feedback (FFB) pathways of a leg extensor muscle on hopping stability, performance and efficiency (metabolic effort)...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28970784/tonically-active-%C3%AE-5gabaa-receptors-reduce-motoneuron-excitability-and-decrease-the-monosynaptic-reflex
#7
Martha Canto-Bustos, Emanuel Loeza-Alcocer, Carlos A Cuellar, Paulina Osuna, David Elias-Viñas, Vinicio Granados-Soto, Elías Manjarrez, Ricardo Felix, Rodolfo Delgado-Lezama
Motoneurons, the final common path of the Central Nervous System (CNS), are under a complex control of its excitability in order to precisely translate the interneuronal pattern of activity into skeletal muscle contraction and relaxation. To fulfill this relevant function, motoneurons are provided with a vast repertoire of receptors and channels, including the extrasynaptic GABAA receptors which have been poorly investigated. Here, we confirmed that extrasynaptic α5 subunit-containing GABAA receptors localize with choline acetyltransferase (ChAT) positive cells, suggesting that these receptors are expressed in turtle motoneurons as previously reported in rodents...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28963128/hind-limb-motoneurons-activity-during-fictive-locomotion-or-scratching-induced-by-pinna-stimulation-serotonin-or-glutamic-acid-in-brain-cortex-ablated-cats
#8
Sergio H Duenas-Jimenez, Luis Castillo Hernandez, Braniff de la Torre Valdovinos, Gerardo Mendizabal Ruiz, Judith M Duenas Jimenez, Viviana Ramirez Abundis, Irene Guadalupe Aguilar Garcia
In brain cortex-ablated cats (BCAC), hind limb motoneurons activity patterns were studied during fictive locomotion (FL) or fictive scratching (FS) induced by pinna stimulation. In order to study motoneurons excitability: heteronymous monosynaptic reflex (HeMR), intracellular recording, and individual Ia afferent fiber antidromic activity (AA) were analyzed. The intraspinal cord microinjections of serotonin or glutamic acid effects were made to study their influence in FL or FS During FS, HeMR amplitude in extensor and bifunctional motoneurons increased prior to or during the respective electroneurogram (ENG)...
September 2017: Physiological Reports
https://www.readbyqxmd.com/read/28882919/a-randomised-controlled-cross-over-double-blind-pilot-study-protocol-on-thc-cbd-oromucosal-spray-efficacy-as-an-add-on-therapy-for-post-stroke-spasticity
#9
RANDOMIZED CONTROLLED TRIAL
Lucio Marinelli, Maurizio Balestrino, Laura Mori, Luca Puce, Gian Marco Rosa, Laura Giorello, Antonio Currà, Francesco Fattapposta, Carlo Serrati, Carlo Gandolfo, Giovanni Abbruzzese, Carlo Trompetto
INTRODUCTION: Stroke is the most disabling neurological disorder and often causes spasticity. Transmucosal cannabinoids (tetrahydrocannabinol and cannabidiol (THC:CBD), Sativex) is currently available to treat spasticity-associated symptoms in patients with multiple sclerosis. Cannabinoids are being considered useful also in the treatment of pain, nausea and epilepsy, but may bear and increased risk for cardiovascular events. Spasticity is often assessed with subjective and clinical rating scales, which are unable to measure the increased excitability of the monosynaptic reflex, considered the hallmark of spasticity...
September 7, 2017: BMJ Open
https://www.readbyqxmd.com/read/28724781/muscle-disuse-caused-by-botulinum-toxin-injection-leads-to-increased-central-gain-of-the-stretch-reflex-in-the-rat
#10
Jessica Pingel, Hans Hultborn, Lui Näslund-Koch, Dennis B Jensen, Jacob Wienecke, Jens Bo Nielsen
Botulinum toxin (Btx) is used in children with cerebral palsy and in other neurological patients to diminish spasticity and reduce the risk of development of contractures. We investigated changes in the central gain of the stretch reflex circuitry in response to Btx injection in the triceps surae muscle in rats. Experiments were performed in 21 rats. Eight rats were a control group, and 13 rats were injected with 6 IU of Btx in the left triceps surae muscle. Two weeks after Btx injection, larger monosynaptic reflexes (MSR) were recorded from the left (injected) than the right (noninjected) L4 + L5 ventral roots following stimulation of the corresponding dorsal roots...
October 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28662201/neural-effects-of-muscle-stretching-on-the-spinal-reflexes-in-multiple-lower-limb-muscles
#11
Yohei Masugi, Hiroki Obata, Daisuke Inoue, Noritaka Kawashima, Kimitaka Nakazawa
While previous studies have shown that muscle stretching suppresses monosynaptic spinal reflex excitability in stretched muscles, its effects on non-stretched muscles is still largely unknown. The purpose of this study was to examine the effects of muscle stretching on monosynaptic spinal reflex in non-stretched muscles. Ten healthy male subjects participated in this study. Muscle stretching of the right triceps surae muscle was performed using a motor torque device for 1 minute. Three different dorsiflexion torques (at approximately 5, 10, and 15 Nm) were applied during muscle stretching...
2017: PloS One
https://www.readbyqxmd.com/read/28638331/monosynaptic-stretch-reflex-fails-to-explain-the-initial-postural-response-to-sudden-lateral-perturbations
#12
Andreas Mühlbeier, Christian Puta, Kim J Boström, Heiko Wagner
Postural reflexes are essential for locomotion and postural stability, and may play an important role in the etiology of chronic back pain. It has recently been theoretically predicted, and with the help of unilateral perturbations of the trunk experimentally confirmed that the sensorimotor control must lower the reflex amplitude for increasing reflex delays to maintain spinal stability. The underlying neuromuscular mechanism for the compensation of postural perturbations, however, is not yet fully understood...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28623664/mechanosensory-neurons-control-the-timing-of-spinal-microcircuit-selection-during-locomotion
#13
Steven Knafo, Kevin Fidelin, Andrew Prendergast, Po-En Brian Tseng, Alexandre Parrin, Charles Dickey, Urs Lucas Böhm, Sophie Nunes Figueiredo, Olivier Thouvenin, Hugues Pascal-Moussellard, Claire Wyart
Despite numerous physiological studies about reflexes in the spinal cord, the contribution of mechanosensory feedback to active locomotion and the nature of underlying spinal circuits remains elusive. Here we investigate how mechanosensory feedback shapes active locomotion in a genetic model organism exhibiting simple locomotion-the zebrafish larva. We show that mechanosensory feedback enhances the recruitment of motor pools during active locomotion. Furthermore, we demonstrate that inputs from mechanosensory neurons increase locomotor speed by prolonging fast swimming at the expense of slow swimming during stereotyped acoustic escape responses...
June 19, 2017: ELife
https://www.readbyqxmd.com/read/28576940/descending-systems-direct-development-of-key-spinal-motor-circuits
#14
Calvin C Smith, Julian F R Paton, Samit Chakrabarty, Ronaldo M Ichiyama
The formation of mature spinal motor circuits is dependent on both activity-dependent and independent mechanisms during postnatal development. During this time, reorganization and refinement of spinal sensorimotor circuits occurs as supraspinal projections are integrated. However, specific features of postnatal spinal circuit development remain poorly understood. This study provides the first detailed characterization of rat spinal sensorimotor circuit development in the presence and absence of descending systems...
June 28, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28570549/non-invasive-assessment-of-changes-in-corticomotoneuronal-transmission-in-humans
#15
Wolfgang Taube, Christian Leukel, Jens Bo Nielsen, Jesper Lundbye-Jensen
The corticospinal pathway is the major pathway connecting the brain with the muscles and is therefore highly relevant for movement control and motor learning. There exists a number of noninvasive electrophysiological methods investigating the excitability and plasticity of this pathway. However, most methods are based on quantification of compound potentials and neglect that the corticospinal pathway consists of many different connections that are more or less direct. Here, we present a method that allows testing excitability of different fractions of the corticospinal transmission...
May 24, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28543879/vglut1-synapses-and-p-boutons-on-regenerating-motoneurons-after-nerve-crush
#16
Adam J Schultz, Travis M Rotterman, Anirudh Dwarakanath, Francisco J Alvarez
Stretch-sensitive Ia afferent monosynaptic connections with motoneurons form the stretch reflex circuit. After nerve transection, Ia afferent synapses and stretch reflexes are permanently lost, even after regeneration and reinnervation of muscle by motor and sensory afferents is completed in the periphery. This loss greatly affects full recovery of motor function. However, after nerve crush, reflex muscle forces during stretch do recover after muscle reinnervation and reportedly exceed 140% baseline values...
September 1, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28405011/plasticity-within-excitatory-and-inhibitory-pathways-of-the-vestibulo-spinal-circuitry-guides-changes-in-motor-performance
#17
Diana E Mitchell, Charles C Della Santina, Kathleen E Cullen
Investigations of behaviors with well-characterized circuitry are required to understand how the brain learns new motor skills and ensures existing behaviors remain appropriately calibrated over time. Accordingly, here we recorded from neurons within different sites of the vestibulo-spinal circuitry of behaving macaque monkeys during temporally precise activation of vestibular afferents. Behaviorally relevant patterns of vestibular nerve activation generated a rapid and substantial decrease in the monosynaptic responses recorded at the first central stage of processing from neurons receiving direct input from vestibular afferents within minutes, as well as a decrease in the compensatory reflex response that lasted up to 8 hours...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28380320/reappraisal-of-the-f-m-amplitude-ratio-in-carpal-tunnel-syndrome
#18
F Ginanneschi, M Mondelli, A Aretini, Alessandro Rossi
The F-wave/M-wave amplitude (F/M-amp) ratio has been shown to be increased in peripheral neuropathies, provided the maximum M-wave is relatively preserved. Reduced M-wave amplitudes and central facilitation of antidromically-induced reactivation of the anterior horn cells' axon hillocks (F-wave) are believed to contribute to higher F/M-amp ratios. The present study was undertaken to re-evaluate mechanisms responsible for higher F/M-amp ratios in carpal tunnel syndrome (CTS). We enrolled 232 cases affected by CTS and 108 controls...
January 2017: Functional Neurology
https://www.readbyqxmd.com/read/28244163/chemogenetic-enhancement-of-functional-recovery-after-a-sciatic-nerve-injury
#19
Poonam B Jaiswal, Arthur W English
Designer receptors exclusively activated by designer drugs (DREADDs) are chemogenetic tools used to modulate neuronal excitability. We hypothesized that activation of excitatory (Gq) DREADD by its designer ligand, clozapine-N-oxide (CNO), would increase the excitability of neurons whose axons have been transected following peripheral nerve injury, and that this increase will lead to an enhanced functional recovery. The lateral gastrocnemius (LG) muscle of adult female Lewis rats was injected unilaterally with AAV9- hsyn- hM3Dq-mCherry (7...
May 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/27891626/does-trans-spinal-and-local-dc-polarization-affect-presynaptic-inhibition-and-post-activation-depression
#20
D Kaczmarek, J Ristikankare, E Jankowska
KEY POINTS: Trans-spinal polarization was recently introduced as a means to improve deficient spinal functions. However, only a few attempts have been made to examine the mechanisms underlying DC actions. We have now examined the effects of DC on two spinal modulatory systems, presynaptic inhibition and post-activation depression, considering whether they might weaken exaggerated spinal reflexes and enhance excessively weakened ones. Direct current effects were evoked by using local intraspinal DC application (0...
March 1, 2017: Journal of Physiology
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