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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
Vaughan G Macefield, Thomas P Knellwolf
Muscle spindles are ubiquitous encapsulated mechanoreceptors found in most mammalian muscles. There are two types of endings, primary and secondary, and both are sensitive to changes in muscle length and velocity, with the primary endings having a greater dynamic sensitivity. Unlike other mechanoreceptors in the somatosensory system, muscle spindles are unique in possessing motor innervation, via  motoneurons (fusimotor neurons), that control their sensitivity to stretch. Much of what we know about human muscles spindles comes from studying the behavior of their afferents via intraneural microelectrodes (microneurography) inserted into accessible peripheral nerves...
April 18, 2018: Journal of Neurophysiology
Philippa M Warren, Cara Campanaro, Frank J Jacono, Warren J Alilain
Mid-cervical spinal cord contusion disrupts both the pathways and motoneurons vital to the activity of inspiratory muscles. The present study was designed to determine if a rat contusion model could result in a measurable deficit to both ventilatory and respiratory motor function under "normal" breathing conditions at acute to chronic stages post trauma. Through whole body plethysmography and electromyography we assessed respiratory output from three days to twelve weeks after a cervical level 3 (C3) contusion...
April 10, 2018: Experimental Neurology
Sian F Irvine, Jessica C F Kwok
Perineuronal nets (PNNs) are extracellular matrix structures surrounding neuronal sub-populations throughout the central nervous system, regulating plasticity. Enzymatically removing PNNs successfully enhances plasticity and thus functional recovery, particularly in spinal cord injury models. While PNNs within various brain regions are well studied, much of the composition and associated populations in the spinal cord is yet unknown. We aim to investigate the populations of PNN neurones involved in this functional motor recovery...
April 12, 2018: International Journal of Molecular Sciences
Chenyun Dai, Yang Zheng, Xiaogang Hu
Robotic assistant-based therapy holds great promise to improve the functional recovery of stroke survivors. Numerous neural-machine interface techniques have been used to decode the intended movement to control robotic systems for rehabilitation therapies. In this case report, we tested the feasibility of estimating finger extensor muscle forces of a stroke survivor, based on the decoded descending neural drive through population motoneuron discharge timings. Motoneuron discharge events were obtained by decomposing high-density surface electromyogram (sEMG) signals of the finger extensor muscle...
2018: Frontiers in Neurology
Jacob J Riehm, Lijun Wang, Ghanashyam Ghadge, Michael Teng, Ana M Correa, Jeremy D Marks, Raymond P Roos, Michael J Allen
Here we report a gain in function for mutant (mt) superoxide dismutase I (SOD1), a cause of familial amyotrophic lateral sclerosis (FALS), wherein small soluble oligomers of mtSOD1 acquire a membrane toxicity. Phosphatidylglycerol (PG) lipid domains are selectively targeted, which could result in membrane damage or "toxic channels" becoming active in the bilayer. This PG-selective SOD1-mediated membrane toxicity is largely reversible in vitro by a widely-available FDA-approved surfactant and membrane-stabilizer P188...
April 5, 2018: Neurobiology of Disease
Amaya Rando, Diego Pastor, Mari Carmen Viso-León, Anna Martínez, Raquel Manzano, Xavier Navarro, Rosario Osta, Salvador Martínez
BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive muscle weakness, paralysis and death. There is no effective treatment for ALS and stem cell therapy has arisen as a potential therapeutic approach. METHODS: SOD1 mutant mice were used to study the potential neurotrophic effect of bone marrow cells grafted into quadriceps femoris muscle. RESULTS: Bone marrow intramuscular transplants resulted in increased longevity with improved motor function and decreased motoneuron degeneration in the spinal cord...
April 6, 2018: Stem Cell Research & Therapy
Paul J May, Susan Warren, Paul D R Gamlin, Isabelle Billig
Purpose: These experiments were designed to reveal the location of the premotor neurons that have previously been designated physiologically as the midbrain near response cells controlling vergence, lens accommodation, and pupillary constriction in response to target distance. Methods: To identify this population, the fixed N2c strain of rabies virus was injected into the ciliary body of seven Macaca fascicularis monkeys. The virus was trans-synaptically transported to the brain...
March 1, 2018: Investigative Ophthalmology & Visual Science
Mohsen Naji, Maxim Komarov, Giri P Krishnan, Atul Malhotra, Frank L Powell, Irma Rukhadze, Victor B Fenik, Maxim Bazhenov
In patients with obstructive sleep apnea (OSA) the pharyngeal muscles become relaxed during sleep, which leads to a partial or complete closure of upper airway. Experimental studies suggest that withdrawal of noradrenergic and serotonergic drives importantly contribute to depression of hypoglossal motoneurons and, therefore, may contribute to OSA pathophysiology; however, specific cellular and synaptic mechanisms remain unknown. In this new study, we developed a biophysical network model to test the hypothesis that, in order to explain experimental observations, the neuronal network for monoaminergic control of excitability of hypoglossal motoneurons needs to include excitatory and inhibitory perihypoglossal interneurons that mediate noradrenergic and serotonergic drives to hypoglossal motoneurons...
April 4, 2018: Journal of Neurophysiology
S Jayne Garland, Alessio Gallina, Courtney L Pollock, Tanya D Ivanova
This study examined the task-dependency of sensory inputs on motoneuron excitability by comparing the inhibitory post-synaptic potential (IPSP) evoked by stimulation of the sural nerve between a standing postural task (Free Standing) and a comparable voluntary isometric contraction performed in supine (Lying Supine). We hypothesized that there would be a smaller IPSP in standing than in supine, based on the task dependence of the ankle plantarflexor activity to the standing task. Ten healthy participants participated in a total of 15 experiments...
April 4, 2018: Journal of Neurophysiology
Lynn T Landmesser
Birds and mammals, both being amniotes, share many common aspects of development. Thus our understanding of how limb-innervating mammalian spinal motor circuits develop was greatly influenced by the use of the avian embryo (chick/quail) to bring about experimental perturbations to identify basic underlying mechanisms. These included embryonic surgery, the application of drugs to influence activity or molecular interactions, and the ability to observe motor behavior and make physiological recordings in intact developing embryos...
2018: International Journal of Developmental Biology
Deborah O Setter, Melissa M Haulcomb, Taylor Beahrs, Rena M Meadows, Nicole D Schartz, Sara K Custer, Virginia M Sanders, Kathryn J Jones
BACKGROUND: When nerve transection is performed on adult rodents, a substantial population of neurons survives short-term disconnection from target, and the immune system supports this neuronal survival, however long-term survival remains unknown. Understanding the effects of permanent axotomy on cell body survival is important as target disconnection is the first pathological occurrence in fatal motoneuron diseases such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA)...
March 25, 2018: Restorative Neurology and Neuroscience
Kojiro Suda, Ibuki Ueoka, Yumiko Azuma, Yuuka Muraoka, Hideki Yoshida, Masamitsu Yamaguchi
Mutations in SLC25A46 gene have been identified in mitochondrial diseases that are sometimes classified as Charcot-Marie-Tooth disease type 2, optic atrophy and Leigh syndrome. Human SLC25A46 functions as a transporter across the outer mitochondrial membrane. However, it is still unknown how the neurodegeneration occurring in these diseases relates to the loss of SLC25A46 function. Drosophila has CG5755 (dSLC25A46) as a single human SLC25A46 homolog. Here we established pan-neuron specific dSLC25A46 knockdown flies, and examined their phenotypes...
March 28, 2018: Brain Research
Hou-Cheng Liang, Jing-Dong Zhang, Pi-Fu Luo, Ying Qiao, An-Le Su, Ting Zhang, Hong-Na Zhu
AIM: To investigate a possible trigeminal proprioceptive-oculomotor neural pathway and explore possible synaptic connections between neurons in this pathway. Attempt to bring a new insight to mechanism of Marcus Gunn syndrome (MGS). METHODS: Anterograde and retrograde tract tracing was applied and combined with immunofluorescent stain in rats. After electrophysiological identifying mesencephalic trigeminal nucleus (Vme) neurons, intracellular injection of tracer was performed to trace axon trajectory...
2018: International Journal of Ophthalmology
Plínio Luna Albuquerque, Mayara Campêlo, Thyciane Mendonça, Luís Augusto Mendes Fontes, Rodrigo de Mattos Brito, Katia Monte-Silva
Repetitive transcranial magnetic stimulation (rTMS) over motor cortex and trans-spinal direct current stimulation (tsDCS) modulate corticospinal circuits in healthy and injured subjects. However, their associated effects with physical exercise is still not defined. This study aimed to investigate the effect of three different settings of rTMS and tsDCS combined with treadmill exercise on spinal cord and cortical excitability of healthy subjects. We performed a triple blind, randomized, sham-controlled crossover study with 12 healthy volunteers who underwent single sessions of rTMS (1Hz, 20Hz and Sham) and tsDCS (anodal, cathodal and Sham) associated with 20 minutes of treadmill walking...
2018: PloS One
Benjamin Zealley, Aubrey D N J de Grey
Theses reviewed in this issue include "An Intranasal GDNF Gene Therapy Approach for Treating Parkinson's Disease", "Controlling Depth of Cellular Quiescence By an Rb-E2F Network Switch", "Immunoregulation of the Central Response to Peripheral Nerve Injury: Motoneuron Survival and Relevance to ALS", and "Single-Cell Whole-Genome Sequencing Reveals Widespread Somatic Copy Number Variations in the Developing Cerebral Cortex".
March 28, 2018: Rejuvenation Research
Maria de Lourdes Martinez-Silva, Rebecca D Imhoff-Manuel, Aarti Sharma, C J Heckman, Neil A Shneider, Francesco Roselli, Daniel Zytnicki, Marin Manuel
Hyperexcitability has been suggested to contribute to motoneuron degeneration in amyotrophic lateral sclerosis (ALS). If this is so, and given that the physiological type of a motor unit determines the relative susceptibility of its motoneuron in ALS, then one would expect the most vulnerable motoneurons to display the strongest hyperexcitability prior to their degeneration, whereas the less vulnerable should display a moderate hyperexcitability, if any. We tested this hypothesis in vivo in two unrelated ALS mouse models by correlating the electrical properties of motoneurons with their physiological types, identified based on their motor unit contractile properties...
March 27, 2018: ELife
Joseph Lombardo, Jianli Sun, Melissa A Harrington
Activity-dependent changes in the properties of the motor system underlie the necessary adjustments in its responsiveness on the basis of the environmental and developmental demands of the organism. Although plastic changes in the properties of the spinal cord have historically been neglected because of the archaic belief that the spinal cord is constituted by a hardwired network that simply relays information to muscles, plenty of evidence has been accumulated showing that synapses impinging on spinal motoneurons undergo short- and long-term plasticity...
2018: PloS One
Arthur B Jenny, Paul D Cheney, Andrew K Jenny
Transverse sections of the monkey cervical spinal cord from a previous study (Jenny and Inukai, 1983) were reanalyzed using Neurolucida to create a three-dimensional display of extensor digitorum communis (EDC) motoneurons and proximal dendrites that had been labeled with horse radish peroxidase (HRP). The EDC motoneuron pool was located primarily in the C8 and T1 segments of the spinal cord. Small motoneurons (cell body areas less than 500 μm2 and presumed to be gamma motoneurons) comprised about ten percent of the motoneurons and were located throughout the length of the motoneuron pool...
March 22, 2018: Neuroscience Letters
Sonja Lehmann, Eliza Esch, Philipp Hartmann, Anand Goswami, Stefan Nikolin, Joachim Weis, Cordian Beyer, Sonja Johann
AIMS: Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of motoneurons and progressive muscle wasting. Inflammatory processes, mediated by non-neuronal cells, such as glial cells, are known to contribute to disease progression. Inflammasomes consist of pattern recognition receptors (PPRs), ASC and caspase 1 and are essential for interleukin (IL) processing and a rapid immune response after tissue damage. Recently, we described inflammasome activation in the spinal cord of ALS patients and in SOD1(G93A) ALS mice...
March 25, 2018: Neuropathology and Applied Neurobiology
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