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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
John A Wolf, Brian N Johnson, Victoria E Johnson, Mary E Putt, Kevin D Browne, Constance J Mietus, Daniel P Brown, Kathryn L Wofford, Douglas H Smith, M Sean Grady, Akiva S Cohen, D Kacy Cullen
Hippocampal-dependent deficits in learning and memory formation are a prominent feature of traumatic brain injury (TBI), however the role of the hippocampus in cognitive dysfunction after concussion (mild TBI) is unknown. We therefore investigated functional and structural changes in the swine hippocampus following TBI using a model of head rotational acceleration that closely replicates the biomechanics and neuropathology of closed-head TBI in humans. We examined neurophysiological changes using a novel ex vivo hippocampal slice paradigm with extracellular stimulation and recording in the dentate gyrus and CA1 occurring at 7 days following non-impact inertial TBI in swine...
March 16, 2017: Journal of Neurotrauma
David Whiteside, Olivia Cant, Molly Connolly, Machar Reid
PURPOSE: Quantifying external workload is fundamental to training prescription in sport. In tennis, global positioning data are imprecise and fail to capture hitting loads. The current gold standard (manual notation) is time intensive and often not possible given players' heavy travel schedules. The aim of this study was to develop an automated stroke classification system to help quantify hitting load in tennis. METHODS: 18 athletes wore an inertial measurement unit (IMU) on their wrist during 66 video-recorded training sessions...
February 9, 2017: International Journal of Sports Physiology and Performance
Mogens Andreasen, Steen Nedergaard
The loop diuretic furosemide is known to have anticonvulsant effects, believed to be exerted through blockade of glial Na(+)-K(+)-2Cl(-) cotransport causing altered volume regulation in brain tissue. The possibility that direct effects of furosemide on neuronal properties could also be involved is supported by previous observations, but such effects have not been thoroughly investigated. In the present study we show that furosemide has two opposing effects on stimulus-induced postsynaptic excitation in the nonepileptic rat hippocampal slice: 1) an enhancement of e-s coupling, which depended on intact GABAA transmission and was partially mimicked by selective blockade of K(+)-2Cl(-) cotransport, and 2) a decrement of field excitatory postsynaptic potentials...
April 1, 2017: Journal of Neurophysiology
Maria Burkovetskaya, Nikolay Karpuk, Tammy Kielian
Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) is a fatal lysosomal storage disease caused by autosomal recessive mutations in CLN3. JNCL is typified by progressive neurodegeneration that has been suggested to occur from excessive excitatory and impaired inhibitory synaptic input; however, no studies to date have directly evaluated neuronal function. To examine changes in neuronal activity with advancing disease, electrophysiological recordings were performed in the CA1 hippocampus (HPC) and visual cortex (VC) of acute brain slices from Cln3(Δex7/8) mice at 1, 4, 8, and 12months of age...
December 30, 2016: Neurobiology of Disease
Lydia P Kudina, Regina E Andreeva
Motoneuron excitability is a critical property for information processing during motor control. F-wave (a motoneuronal recurrent discharge evoked by a motor antidromic volley) is often used as a criterion of motoneuron pool excitability in normal and neuromuscular diseases. However, such using of F-wave calls in question. The present study was designed to explore excitability of single low-threshold motoneurons during their natural firing in healthy humans and to ascertain whether F-wave is a correct measure of motoneuronal excitability...
March 2017: Neurological Sciences
Mehdi A J van den Bos, Nimeshan Geevasinga, Parvathi Menon, David Burke, Matthew C Kiernan, Steve Vucic
Voluntary contraction leads to facilitation of motor-evoked potentials (MEPs) producing greater amplitude, shorter onset latency, and prolonged duration of the electromyography potential. Whereas hyperexcitability of spinal motoneurons and changes in descending corticospinal volleys have been proposed as putative mechanisms for changes in MEP amplitude and onset latency, a contribution of propriospinal interneurons, exerting modulatory effects on α-motoneurons, has been proposed as a potential explanation for prolongation of MEP duration...
March 1, 2017: Journal of Neurophysiology
Luiz H P Vieira, Vitor L DE Andrade, Rodrigo L Aquino, Renato Moraes, Fabio A Barbieri, Sérgio A Cunha, Bruno L Bedo, Paulo R Santiago
BACKGROUND: The main aim of this study was to verify the relationship between the classification of coaches and actual performance in field tests that measure the kicking performance in young soccer players, using the K--means clustering technique. METHODS: Twenty--three U--14 players performed eight tests to measure their kicking performance. Four experienced coaches provided a rating for each player as follows: 1--poor, 2--below average, 3--average, 4--very good, 5-excellent as related to three parameters (i...
December 16, 2016: Journal of Sports Medicine and Physical Fitness
Saeka Tomatsu, Geehee Kim, Joachim Confais, Kazuhiko Seki
Presynaptic inhibition of the sensory input from the periphery to the spinal cord can be evaluated directly by intra-axonal recording of primary afferent depolarization (PAD) or indirectly by intraspinal microstimulation (excitability testing). Excitability testing is superior for use in normal behaving animals, because this methodology bypasses the technically challenging intra-axonal recording. However, use of excitability testing on the muscle or joint afferent in intact animals presents its own technical challenges...
February 1, 2017: Journal of Neurophysiology
Miriam Schrafl-Altermatt, Volker Dietz
We investigated the role of ipsilateral ascending pathways in the neural coupling underlying cooperative hand movements of stroke subjects. Ipsi- and contralateral somatosensory evoked potentials (SSEP) were recorded following ulnar nerve stimulation during cooperative and non-cooperative hand movements. The amplitude ratio, that is, ipsilateral divided by contralateral amplitude, was highest during the cooperative task when the affected arm was stimulated, reflecting an enhanced afferent volley to the unaffected hemisphere...
November 2016: Annals of Clinical and Translational Neurology
Nicolas Gueugneau, Sidney Grosprêtre, Paul Stapley, Romuald Lepers
High-frequency neuromuscular electrical stimulation (HF NMES) induces muscular contractions through neural mechanisms that partially match physiological motor control. Indeed, a portion of the contraction arises from central mechanisms, whereby spinal motoneurons are recruited through the evoked sensory volley. However, the involvement of supraspinal centers of motor control during such stimulation remains poorly understood. Therefore, we tested whether a single HF NMES session applied to the upper limb influences interhemispheric inhibition (IHI) from left to right motor cortex (M1)...
January 1, 2017: Journal of Neurophysiology
Anastasia Shulga, Aleksandra Zubareva, Pantelis Lioumis, Jyrki P Mäkelä
Background: In spinal paired associative stimulation (PAS), orthodromic and antidromic volleys elicited by transcranial magnetic stimulation (TMS) and peripheral nerve stimulation (PNS) coincide at corticomotoneuronal synapses at the spinal cord. The interstimulus interval (ISI) between TMS and PNS determines whether PAS leads to motor-evoked potential (MEP) potentiation or depression. PAS applied as a long-term treatment for neurological patients might alter conduction of neural fibers over time. Moreover, measurements of motoneuron conductance for determination of ISIs may be challenging in these patients...
2016: Frontiers in Human Neuroscience
Catherine Mercier, Martin Gagné, Karen T Reilly, Laurent J Bouyer
Sensorimotor integration is altered in people with chronic pain. While there is substantial evidence that pain interferes with neural activity in primary sensory and motor cortices, much less is known about its impact on integrative sensorimotor processes. Here, the short latency afferent inhibition (SAI) paradigm was used to assess sensorimotor integration in the presence and absence of experimental cutaneous heat pain applied to the hand. Ulnar nerve stimulation was combined with transcranial magnetic stimulation to condition motor evoked potentials (MEPs) in the first dorsal interosseous muscle...
September 29, 2016: Brain Sciences
John Cirillo, Winston D Byblow
Paired-pulse transcranial magnetic stimulation (TMS) can be used to probe inhibitory activity in primary motor cortex (M1). Recruitment of descending volleys with TMS depends on the induced current direction in M1. Anterior-posterior (AP) stimulation preferentially activates late indirect- (I-) waves that are most susceptible to paired-pulse TMS. Threshold tracking TMS can assess intracortical inhibition; however, previous studies have only used a current direction that preferentially recruits early I-waves [posterior-anterior (PA)]...
October 2016: European Journal of Neuroscience
Charles A Hass, Lindsey L Glickfeld
Optogenetic activation of axons is a powerful approach for determining the synaptic properties and impact of long-range projections both in vivo and in vitro. However, because of the difficulty of measuring activity in axons, our knowledge of the reliability of optogenetic axonal stimulation has relied on data from somatic recordings. Yet, there are many reasons why activation of axons may not be comparable to cell bodies. Thus we have developed an approach to more directly assess the fidelity of optogenetic activation of axonal projections...
November 1, 2016: Journal of Neurophysiology
Gabrielle Todd, Janet L Taylor, Simon C Gandevia
This article reviews the use of transcranial magnetic stimulation (TMS) over the motor cortex to make estimates of the level of voluntary drive to muscles. The method, described in 2003 (Todd et al. J Physiol 551: 661-671, 2003), uses a TMS pulse to produce descending corticospinal volleys that synaptically activate motoneurons, resulting in a muscle twitch. Linear regression of the superimposed twitch amplitude and voluntary force (or torque) can generate an "estimated" resting twitch for muscles involved in a task...
September 1, 2016: Journal of Applied Physiology
Antonino Naro, Antonino Leo, Antonio Buda, Alfredo Manuli, Alessia Bramanti, Placido Bramanti, Rocco Salvatore Calabrò
Behavioral responsiveness and awareness levels correlate with the degree of functional connectivity within cortical-thalamocortical networks, whose breakdown accounts for chronic disorders of consciousness (DOC). Our study was aimed at assessing the role of the primary motor area (M1) and premotor-M1 circuitry dysfunction in motor output deterioration in minimally conscious state (MCS) and unresponsive wakefulness syndrome (UWS) patients. As a control group, we included a healthy subject (HC) sample in the study...
September 1, 2016: Brain Research
Kenneth C Catania
In March 1800, Alexander von Humboldt observed the extraordinary spectacle of native fisherman collecting electric eels (Electrophorus electricus) by "fishing with horses" [von Humboldt A (1807) Ann Phys 25:34-43]. The strategy was to herd horses into a pool containing electric eels, provoking the eels to attack by pressing themselves against the horses while discharging. Once the eels were exhausted, they could be safely collected. This legendary tale of South American adventures helped propel Humboldt to fame and has been recounted and illustrated in many publications, but subsequent investigators have been skeptical, and no similar eel behavior has been reported in more than 200 years...
June 21, 2016: Proceedings of the National Academy of Sciences of the United States of America
Aaron Z Bailey, Michael J Asmussen, Aimee J Nelson
Short-latency afferent inhibition (SAI) is characterized by the suppression of the transcranial magnetic stimulation motor evoked potential (MEP) by the cortical arrival of a somatosensory afferent volley. It remains unknown whether the magnitude of SAI reflects changes in the sensory afferent volley, similar to that observed for somatosensory evoked potentials (SEPs). The present study investigated stimulus-response relationships between sensory nerve action potentials (SNAPs), SAI, and SEPs and their interrelatedness...
August 1, 2016: Journal of Neurophysiology
J Meléndez-Gallardo, A Eblen-Zajjur
Most of the endogenous pain modulation (EPM) involves the spinal dorsal horn (SDH). EPM including diffuse noxious inhibitory controls have been extensively described in oligoneuronal electrophysiological recordings but less attention had been paid to responses of the SDH neuronal population to heterotopic noxious stimulation (HNS). Spinal somatosensory-evoked potentials (SEP) offer the possibility to evaluate the neuronal network behavior, reflecting the incoming afferent volleys along the entry root, SDH interneuron activities and the primary afferent depolarization...
September 2016: Neurological Sciences
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