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Monosynaptic reflex

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
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
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...
February 28, 2017: European Journal of Neuroscience
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
Fumiyasu Imai, Xiaoting Chen, Matthew T Weirauch, Yutaka Yoshida
In contrast to our knowledge of mechanisms governing circuit formation, our understanding of how neural circuits are maintained is limited. Here, we show that Dicer, an RNaseIII protein required for processing microRNAs (miRNAs), is essential for maintenance of the spinal monosynaptic stretch reflex circuit in which group Ia proprioceptive sensory neurons form direct connections with motor neurons. In postnatal mice lacking Dicer in proprioceptor sensory neurons, there are no obvious defects in specificity or formation of monosynaptic sensory-motor connections...
November 22, 2016: Cell Reports
Sumin Yoon, SeungHwan Lee, Kyung-Sang Yu, Sung-Vin Yim, Bo-Hyung Kim
BACKGROUNDS: Baclofen is used as a skeletal muscle relaxant for multiple sclerosis patients. It depresses the transmission of monosynaptic and polysynaptic reflex by stimulating GABAβ (gamma-aminobutyric acid) receptors. OBJECTIVES: The aim of this study was to compare the pharmacokinetic characteristics of two 10-mg baclofen formulations and to assess bioequivalence. METHODS: A randomized, single-dose, two-period, two-sequence crossover study was conducted in healthy male subjects...
November 23, 2016: International Journal of Clinical Pharmacology and Therapeutics
Katsuhiro Shinozaki, Mitsuhiro Nito, Shinji Kobayashi, Masahiro Hayashi, Takuji Miyasaka, Wataru Hashizume, Masaomi Shindo, Akira Naito
Spinal reflex arcs mediated by low-threshold (group I) afferents from muscle spindles and Golgi tendon organs modulate motoneuron excitabilities to coordinate smooth movements. In this study, the reflex arcs between the brachioradialis (BR) and extensor carpi radialis muscles (ECR) were examined in nine healthy human subjects using a post-stimulus time-histogram method. Electrical conditioning stimuli (ES) to the radial nerve branches innervating BR (BR nerve) and ECR (ECR nerve) with the intensity just below the motor threshold were delivered and firings of the ECR and BR motor units were recorded in 6 and 7 of the nine subjects, respectively...
January 2017: Neuroscience Research
Olga Gajewska-Woźniak, Kamil Grycz, Julita Czarkowska-Bauch, Małgorzata Skup
The effects of stimulation of low-threshold proprioceptive afferents in the tibial nerve on two types of excitatory inputs to α-motoneurons were tested. The first input is formed by glutamatergic Ia sensory afferents contacting monosynaptically α-motoneurons. The second one is the cholinergic input originating from V0c-interneurons, located in lamina X of the spinal cord, modulating activity of α-motoneurons via C-terminals. Our aim was to clarify whether enhancement of signaling to ankle extensor α-motoneurons, via direct electrical stimulation addressed predominantly to low-threshold proprioceptive fibers in the tibial nerve of awake rats, will affect Ia glutamatergic and cholinergic innervation of α-motoneurons of lateral gastrocnemius (LG)...
2016: PloS One
Tsuyoshi Nakajima, Kiyotaka Kamibayashi, Taku Kitamura, Tomoyoshi Komiyama, E Paul Zehr, Kimitaka Nakazawa
Both active and passive rhythmic limb movements reduce the amplitude of spinal cord Hoffmann (H-) reflexes in muscles of moving and distant limbs. This could have clinical utility in remote modulation of the pathologically hyperactive reflexes found in spasticity after stroke or spinal cord injury. However, such clinical translation is currently hampered by a lack of critical information regarding the minimum or effective duration of passive movement needed for modulating spinal cord excitability. We therefore investigated the H-reflex modulation in the flexor carpi radialis (FCR) muscle during and after various durations (5, 10, 15, and 30 min) of passive stepping in 11 neurologically normal subjects...
2016: Frontiers in Human Neuroscience
Jill Cannoy, Sam Crowley, Allen Jarratt, Kelly LeFevere Werts, Krista Osborne, Sohee Park, Arthur W English
Following peripheral nerve injury, moderate daily exercise conducted on a level treadmill results in enhanced axon regeneration and modest improvements in functional recovery. If the exercise is conducted on an upwardly inclined treadmill, even more motor axons regenerate successfully and reinnervate muscle targets. Whether this increased motor axon regeneration also results in greater improvement in functional recovery from sciatic nerve injury was studied. Axon regeneration and muscle reinnervation were studied in Lewis rats over an 11 wk postinjury period using stimulus evoked electromyographic (EMG) responses in the soleus muscle of awake animals...
September 1, 2016: Journal of Neurophysiology
Danilo de Oliveira Silva, Fernando Henrique Magalhães, Nathálie Clara Faria, Deisi Ferrari, Marcella Ferraz Pazzinatto, Evangelos Pappas, Fábio Mícolis de Azevedo
OBJECTIVE: To determine the association between the amplitude of vastus medialis (VM) Hoffmann reflex (H-reflex) and pain level, self-reported physical function, and chronicity of pain in women with patellofemoral pain (PFP). DESIGN: Cross-sectional study. SETTING: Laboratory of biomechanics and motor control. PARTICIPANTS: Women diagnosed with PFP (N=15) aged 18 to 35 years. INTERVENTIONS: Not applicable...
January 2017: Archives of Physical Medicine and Rehabilitation
M Jarjees, A Vučković
OBJECTIVES: The aim of this study was to explore the possibility of the short-term modulation of the soleus H reflex through self-induced modulation of the sensory-motor rhythm (SMR) as measured by electroencephalography (EEG) at Cz. METHODS: Sixteen healthy participants took part in one session of neuromodulation. Motor imagery and mental math were strategies for decreasing SMR, while neurofeedback was used to increase SMR. H reflex of the soleus muscle was elicited by stimulating tibial nerve when SMR reached a pre-defined threshold and was averaged over 5 trials...
August 2016: International Journal of Psychophysiology
Zhi-Ling Guo, John C Longhurst, Stephanie C Tjen-A-Looi, Liang-Wu Fu
The external lateral parabrachial nucleus (elPBN) within the pons and rostral ventrolateral medulla (rVLM) contributes to central processing of excitatory cardiovascular reflexes during stimulation of cardiac sympathetic afferent nerves (CSAN). However, the importance of elPBN cardiovascular neurons in regulation of rVLM activity during CSAN activation remains unclear. We hypothesized that CSAN stimulation excites the elPBN cardiovascular neurons and, in turn, increases rVLM activity through elPBN-rVLM projections...
August 1, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Fumiyasu Imai, David R Ladle, Jennifer R Leslie, Xin Duan, Tilat A Rizvi, Georgianne M Ciraolo, Yi Zheng, Yutaka Yoshida
UNLABELLED: Spinal reflex circuit development requires the precise regulation of axon trajectories, synaptic specificity, and synapse formation. Of these three crucial steps, the molecular mechanisms underlying synapse formation between group Ia proprioceptive sensory neurons and motor neurons is the least understood. Here, we show that the Rho GTPase Cdc42 controls synapse formation in monosynaptic sensory-motor connections in presynaptic, but not postsynaptic, neurons. In mice lacking Cdc42 in presynaptic sensory neurons, proprioceptive sensory axons appropriately reach the ventral spinal cord, but significantly fewer synapses are formed with motor neurons compared with wild-type mice...
May 25, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Brent Myers, Jessie R Scheimann, Ana Franco-Villanueva, James P Herman
In response to stress, defined as a real or perceived threat to homeostasis or well-being, brain systems initiate divergent physiological and behavioral processes that mobilize energy and promote adaptation. The brainstem contains multiple nuclei that engage in autonomic control and reflexive responses to systemic stressors. However, brainstem nuclei also play an important role in neuroendocrine responses to psychogenic stressors mediated by the hypothalamic-pituitary-adrenocortical axis. Further, these nuclei integrate neuroendocrine responses with stress-related behaviors, significantly impacting mood and anxiety...
March 2017: Neuroscience and Biobehavioral Reviews
Michael P Matott, David D Kline
Serotonin (5-HT) is a potent neuromodulator with multiple receptor types within the cardiorespiratory system, including the nucleus tractus solitarii (nTS)--the central termination site of visceral afferent fibers. The 5-HT7 receptor facilitates cardiorespiratory reflexes through its action in the brainstem and likely in the nTS. However, the mechanism and site of action for these effects is not clear. In this study, we examined the expression and function of 5-HT7 receptors in the nTS of Sprague-Dawley rats...
March 15, 2016: Brain Research
Yu Kawaishi, Kazuhisa Domen
Soleus H-reflex reveals down modulation with increased postural difficulty. Role of this posture-related reflex modulation is thought to shift movement control toward higher motor centers in order to facilitate more precise postural control. Present study hypothesized that the ability to modulate H-reflex is related to one's ability to dynamically balance while in an unstable posture. This study examined the relationship between dynamic balancing ability and soleus H-reflex posture-related modulation. Thirty healthy adults participated...
February 2016: Journal of Electromyography and Kinesiology
Ombretta Mameli, Marcello Alessandro Caria, Rosalia Pellitteri, Antonella Russo, Salvatore Saccone, Stefania Stanzani
Previous studies performed in rats showed that the whisker-pad motor innervation involves not only the facial nerve, but also some hypoglossal neurons whose axons travel within the trigeminal infraorbital nerve (ION) and target the extrinsic muscles surrounding the whisker-pad macrovibrissae. Furthermore, the electrical stimulation of the ION induced an increase in the EMG activity of these muscles, while the hypoglossal nucleus stimulation elicited evoked potentials and single motor unit responses. However, the existence of a neural network able to involve the XIIth nucleus in macrovibrissae whisking control was totally unknown until now...
March 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Letizia Leocani, Arturo Nuara, Elise Houdayer, Irene Schiavetti, Ubaldo Del Carro, Stefano Amadio, Laura Straffi, Paolo Rossi, Vittorio Martinelli, Carlos Vila, Maria Pia Sormani, Giancarlo Comi
Despite the proven efficacy of Sativex(®) (9-delta-tetrahydrocannabinol plus cannabidiol) oromucosal spray in reducing spasticity symptoms in multiple sclerosis (MS), little is known about the neurophysiological correlates of such effects. The aim of the study was to investigate the effects of Sativex on neurophysiological measures of spasticity (H/M ratio) and corticospinal excitability in patients with progressive MS. This was a randomized, double-blind, placebo-controlled, crossover study. Consecutive subjects with progressive MS and lower limb spasticity referred to our center were randomized to 4 weeks' treatment (including 2 weeks' titration) with Sativex or placebo, with crossover after a 2-week washout...
November 2015: Journal of Neurology
Takeshi Kobayashi, Ken-ichi Otsuguro, Soichiro Yamaguchi, Shigeo Ito
Alpha-2A adrenergic receptor (AR) subtype plays an important role in the analgesic effect of α2-AR agonists. Here, we examined the effects of α2-AR agonists, dexmedetomidine and xylazine, on spinal synaptic transmission in newborn C57BL/6J and α2A-AR mutant mice. Spinal reflex potentials, the monosynaptic reflex potential (MSR) and the slow ventral root potential (sVRP), were measured in isolated spinal cords. The compound action potential was measured in isolated lumbar nerve. Dexmedetomidine and xylazine suppressed both the MSR and sVRP in a concentration-dependent manner...
August 15, 2015: European Journal of Pharmacology
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