Relevant bibliographies by topics / H-reflex

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Academic literature on the topic 'H-reflex'

Author: Grafiati
Published: 4 June 2021
Last updated: 25 January 2025

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Journal articles on the topic "H-reflex"

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McHugh, Daniel J., Jonathan C. Reeser, and Ernest W. Johnson. "H REFLEX AMPLITUDE." American Journal of Physical Medicine & Rehabilitation 76, no. 3 (1997): 185–87. http://dx.doi.org/10.1097/00002060-199705000-00003.

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Carabetta, Vito J. "H wave reflex." Archives of Physical Medicine and Rehabilitation 78, no. 12 (1997): 1394. http://dx.doi.org/10.1016/s0003-9993(97)90320-8.

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Thompson, Aiko K., Xiang Yang Chen, and Jonathan R. Wolpaw. "Soleus H-reflex operant conditioning changes the H-reflex recruitment curve." Muscle & Nerve 47, no. 4 (2012): 539–44. http://dx.doi.org/10.1002/mus.23620.

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Wolpaw, J. R. "Operant conditioning of primate spinal reflexes: the H-reflex." Journal of Neurophysiology 57, no. 2 (1987): 443–59. http://dx.doi.org/10.1152/jn.1987.57.2.443.

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The study of primate memory substrates, the CNS alterations which preserve conditioned responses, requires an experimental model that fulfills two criteria. First, the essential alterations must be in a technically accessible location. Second, they must persist without input from other CNS regions. The spinal cord is the most technically accessible and readily isolated portion of the primate CNS. Recent work has demonstrated that the spinal stretch reflex (SSR), the initial, wholly segmental response to muscle stretch, can be operantly conditioned and suggests that this conditioning may produce persistent spinal alteration. The present study attempted similar operant conditioning of the H-reflex, the electrical analog of the SSR. The primary goals were to demonstrate that spinal reflex conditioning can occur even if the muscle spindle is removed from the reflex arc and to demonstrate conditioning in the lumbosacral cord, which is far preferable to the cervical cord for future studies of neuronal and synaptic mechanisms. Nine monkeys prepared with chronic fine-wire triceps surae (gastrocnemius and soleus) electromyographic (EMG) electrodes were taught by computer to maintain a given level of background EMG activity. At random times, a voltage pulse just above M response (direct muscle response) threshold was delivered to the posterior tibial nerve via a chronically implanted silicon nerve cuff and elicited the triceps surae H-reflex. Under the control mode, reward always followed. Under the HR increases or HR decreases mode, reward followed only if the absolute value of triceps surae EMG from 12 to 22 ms after the pulse (the H-reflex interval) was above (HR increases) or below (HR decreases) a set value. Monkeys completed 3,000-6,000 trials/day over study periods of 2-3 mo. Background EMG and M response amplitude remained stable throughout data collection. H-reflex amplitude remained stable under the control mode. Under the HR increases mode (5 animals) or HR decreases mode (4 animals), H-reflex amplitude (EMG amplitude in the H-reflex interval minus background EMG amplitude) changed appropriately over at least 6 wk. Change appeared to occur in two phases: an abrupt change within the first day, followed by slower change, which continued indefinitely. Change occurred in all three triceps surae muscles (medial and lateral gastrocnemii and soleus). Under the HR increases mode, H-reflex amplitude rose to an average of 213% of control, whereas under the HR decreases mode it fell to an average of 68% of control. The results demonstrate that the H-reflex can be operantly conditioned.(ABSTRACT TRUNCATED AT 400 WORDS)
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Gassel, M. Michael. "Monosynaptic Reflexes (H-Reflex) and Motoneurone Excitability in Man." Developmental Medicine & Child Neurology 11, no. 2 (2008): 193–97. http://dx.doi.org/10.1111/j.1469-8749.1969.tb01417.x.

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Brinkworth, R. S. A., M. Tuncer, K. J. Tucker, S. Jaberzadeh, and K. S. Türker. "Standardization of H-reflex analyses." Journal of Neuroscience Methods 162, no. 1-2 (2007): 1–7. http://dx.doi.org/10.1016/j.jneumeth.2006.11.020.

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Misra, U. K., and C. M. Pandey. "H reflex studies in neurolathyrism." Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section 93, no. 4 (1994): 281–85. http://dx.doi.org/10.1016/0168-5597(94)90030-2.

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Leis, A. A., H. H. Zhou, H. L. Harkey, and W. C. Paske. "H-reflex under general anesthesia." Electroencephalography and Clinical Neurophysiology 98, no. 3 (1996): P11. http://dx.doi.org/10.1016/0013-4694(96)80265-3.

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Larsen, Birgit, and Michael Voigt. "Quadriceps H-Reflex Modulation During Pedaling." Journal of Neurophysiology 96, no. 1 (2006): 197–208. http://dx.doi.org/10.1152/jn.00149.2005.

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The main aims of this study were 1) to investigate possible phase-, speed-, and task-dependent changes in the quadriceps H-reflex during pedaling, and to achieve this, 2) to develop an optimized H-reflex recording and processing procedure for recording of quadriceps H-reflexes during movement. It was hypothesized that the behavior of the quadriceps H-reflex concerning phase, speed, and task dependency corresponds to the behavior of the soleus H-reflex during rhythmical leg movements. The applied H-reflex procedure appeared to be reliable for obtaining the quadriceps H-reflex modulation during leg movement. The vastus lateralis (VL) and rectus femoris (RF) H-reflexes showed a phase-dependent modulation during pedaling at a frequency of 80 rpm with almost parallel changes in the reflex amplitude and motor recruitment level. However, when the speed of movement was reduced from 80 to 40 revolutions per minute (rpm) and crank load simultaneously increased (i.e., a halving of the movement speed with a constant motor recruitment level), the quadriceps H-reflex modulation pattern changed significantly in relation to the pattern of motor recruitment, i.e., at 40 rpm, the reflex excitability remained high during a gradual derecruitment during power generation in downstroke. Comparison of the “operationally defined H-reflex gain function” obtained during 1) pedaling at 80 rpm and 2) isometric quadriceps contractions in sitting position showed no significant task-dependent changes in the quadriceps H-reflex. Consequently, the hypothesis was only partly corroborated, and the findings indicate differences in the neural control of the soleus and the quadriceps muscle during rhythmical movements.
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Panizza, M., S. Lelli, J. Nilsson, and M. Hallett. "H-reflex recovery curve and reciprocal inhibition of H-reflex in different kinds of dystonia." Neurology 40, no. 5 (1990): 824. http://dx.doi.org/10.1212/wnl.40.5.824.

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Dissertations / Theses on the topic "H-reflex"

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Scutter, Sheila. "H-reflex in human masseter." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phs4377.pdf.

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Copies of author's previously published articles inserted. Bibliography: leaves 172-204. H-relexes are used to determine the reflex connections of muscle spindle afferents, the exitability of the motorneuron pool and the integrity of the reflex pathways. However, H-relexes are small and can be difficult to elicit in the masseter, limiting their use in the investigation of the masticatory system. This study investigated the recruitment of masseter motorneurons into the H-reflex, compared to the recruitment occuring during voluntary isometric biting, to determine the distribution of the effective muscle spindle input.
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Grünewald, Matthias Lars. "Einfluss des Anästhetikuns Sevofluran und schmerzhafter Stimuli auf den H-Reflex." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2003. http://dx.doi.org/10.18452/14984.

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Einleitung: Für die Messung der "Narkosetiefe" werden vorwiegend Parameter des Elektroenzephalogramms (EEG) untersucht, welche offenbar keine Aussage zur Unterdrückung von Bewegungen auf Schmerzreize treffen können. Dies ist auch wenig verwunderlich, da Untersuchungen an Tieren die Ausschaltung einer Bewegung auf Schmerzreiz durch Anästhetika auf der spinalen Ebene erwarten lassen. Der spinale H-Reflex, ein elektrisch ausgelöster, monosynaptischer Reflex, wurde bereits zur Überwachung der Unterdrückung von Bewegungen während der Narkose vorgeschlagen. Diese Arbeit diente der vergleichenden Untersuchung der H-Reflex-Amplitude mit EEG-Parametern unter Sevofluran-Narkosen. Es wurden Konzentrations-Wirkungs-Kurven ermittelt, sowie die Eignung als Parameter zur Vorhersage von Bewegungen auf schmerzhafte Reize überprüft. Weiterhin sollte der Effekt des schmerzhaften Reizes auf die H-Reflex-Amplitude selbst aufgeklärt werden. Methodik: Nach Zustimmung der Ethikkommission und schriftlicher Einwilligung wurden 28 Patientinnen in die Studie eingeschlossen. Sie wurden präoperativ untersucht. Nach anfänglicher Vertiefung bis zur Toleranz einer Larynxmaske, wurde die Narkose mit Hilfe der "up-and-down"-Methode auf einen Wert nahe der minimalen alveolären Konzentration (MAC) eingestellt. Nach mindestens 15 Minuten konstanter Konzentration wurde von einem "steady-state" ausgegangen und am volaren Unterarm ein elektrisch ausgelöster Schmerzreiz (Tetanus-Reiz, 60 mA) appliziert. Für die Ermittlung der Konzentrations-Wirkungs-Kurve diente ein pharmakokinetisch-pharmadynamisches Modell, welches auf einem sigmoidalen Emax-Modell beruht. Die Eignung eine Bewegung vorherzusagen wurde anhand der "Prediction Probability" (PK-Wert) überprüft. Ergebnisse: Bei 14 Patientinnen konnte der H-Reflex kontinuierlich über die gesamte Messperiode ausgelöst werden. Die Wachwerte betrugen für die H-Reflex-Amplituden 6,5 (+/- 4,1 SD) mV. Sevofluran unterdrückt die H-Reflex-Amplituden konzentrationsabhängig. Die Unterdrückung konnte gut durch das sigmoidale Modell dargestellt werden (Median - r^2 = 0,96). Die Unterdrückung der H-Reflex-Amplitude unterliegt einer signifikant steileren Konzentrations-Wirkungs-Beziehung als die der EEG-Parameter spektrale Eckfrequenz 95 (SEF95) und bispektraler Index (BIS). Die H-Reflex-Amplitude konnte Bewegungen auf einen Schmerzreiz mit einer PK von 0,74 vorhersagen, während mittels der EEG-Parameter SEF95 und BIS lediglich zufällige Aussagen bezüglich stattfindender Bewegungen getroffen werden können. Der Schmerzreiz veränderte die H-Reflex-Amplitude, das spontane frontale Elektromyogramm und die Herzfrequenz, nicht jedoch die kortikal abgeleiteten Parameter BIS und SEF95. Schlussfolgerung: Aus dieser Arbeit ergeben sich Hinweise, dass die Unterdrückung von Bewegungen auf schmerzhafte Reize und die Unterdrückung der H-Reflex-Amplitude durch Sevofluran eng verknüpft sind. Auch wenn kein kausaler Zusammenhang besteht, so würde dies die hohe Vorhersagekraft der H-Reflex-Amplituden für Bewegungen auf Schmerzreiz erklären. Sie ist zur Überwachung der Unterdrückung von groben gezielten Bewegungen während einer Narkose geeignet. Mittels H-Reflex-Amplituden können Aktivierungen des Rückenmarkes registriert werden, welche auf kortikaler Ebene nicht sichtbar werden. Zukünftige auf dem H-Reflex basierende Studien können weitere Einsichten in die Mechanismen der Anästhesie liefern und behilflich an der Erarbeitung von Richtlinien zur optimalen Medikamentendosierung sein.<br>Introduction: The measurement of "depth of anesthesia" is mostly done by parameters of the electroencephalogram (EEG), which can not make a statement about the suppression of movement due to painful stimulation. This is not surprising, looking at recent animal studies that assume the anesthetic induced unresponsiveness to noxious stimulation at the side of the spinal cord. The spinal H-reflex, an electric induced, monosynaptical reflex has been proposed to monitor the suppression of movements during anesthesia. This dissertation shows a comparative examination of the H-reflex-amplitude and parameters of the EEG under anesthesia with sevoflurane. Concentration-response functions have been determined, the prediction of movement to painful stimulation has been tested. Also the effect of the painful stimulus itself on the H-reflex-amplitude has been discovered. Methods: After approval of the institutional review board and informed consent were obtained, 28 patients were included into this study. The examination has been done prior to surgery. After induction of anesthesia until a laryngeal mask was tolerated, sevoflurane was decreased to a level close to minimum alveolar concentration (MAC) using the "up-and-down" method. After at least 15 minutes of constant sevoflurane concentration a "steady-state" was assumed and a painful electrical stimulation (tetanic stimulus of 60mA) was applied. The concentration-response functions were determined using pharmacokinetic and pharmacodynamic modeling, based on a sigmoid Emax model. To estimate and compare the predictive value of the parameters, prediction probability Pk was calculated. Results: On 14 patients the H-reflex could been measured continuously throughout the study period. At awake level, H-reflexes had a mean amplitude of 6,5 (+/- 4,1 SD) mV. Sevoflurane depresses the H-reflex-amplitude in a concentration dependent way, which was well modeled by the sigmoid Emax model (median r^2 = 0,96). The depression of the H-reflex-amplitude underlies a significant steeper concentration-response function as the EEG-parameters spectral edge frequency (SEF95) and bispectral index (BIS). H-reflex-amplitude could predict movement on to painful stimulation with a Pk value of 0,74, whereas EEG-parameters could only make statements, concering upcoming movements, by chance. The painful stimulation changed H-reflex-amplitude, frontal recorded electromyogram and heart-frequency but not the cortical recorded parameters BIS and SEF95. Conclusions: Results indicate that the suppression of movement and the suppression of the H-reflex-amplitude caused by sevoflurane are close connected. Although it does not imply a causual connection, it would explain the high predictive value of the H-reflex-amplitude for motor responses to noxious stimuli. H-reflex-amplitude can be used to monitor the suppression of gross purposeful movements during sevoflurane anesthesia. Using H-reflex-amplitude spinal activation can be registered, which are not seen on cortical level. Coming up studies based on the H-reflex can help to get more insights into the mechanisms of anesthesia and help to develop guidelines for optimal drug dosing.
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Zeitouni, Anthony G. "A study of tonic otolithic and neck reflex stimulation on the H-reflex in man." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23952.

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At present, despite considerable interest there is no commonly used clinical test of otolith function. The aim of this study was to develop an otolith test which could be used in a clinical setting. Otolith stimulation was provided by Y-axis static head yawing while the subject was supine. Modulation of the H-reflex recruitment ratio was measured. Ten normal subjects and five patients who had suffered an acute vestibular lesion were tested. Since this rotation involved otolith and neck inputs, a control experiment assessed the contribution of neck inputs separately. Neither otolith and neck inputs combined nor neck inputs alone had a demonstrable effect on alpha motorneuron pool excitability. These observations contradict results in the literature. However, there exist important differences between this study and those in the literature. The findings reported here should motivate further work into the effects of otolith and neck inputs on lumbar motorneurons.
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McGarry, James Timothy. "On the nature of stopping a voluntary action." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0025/NQ38942.pdf.

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Pedão, Sabrina Tiago. "Efeitos de diferentes freqüências e amplitudes de vibração unilateral do tendão calcâneo na orientação postural e no reflexo H em humanos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-16042010-104819/.

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Uma vibração aplicada a um tendão muscular aumenta a freqüência de disparos de aferentes, como os de fusos neuromusculares Ia e II, cujas terminações afetam circuitos da medula espinhal e com isto podem influenciar o controle motor. O objetivo deste estudo foi analisar o efeito de vibrações a duas freqüências (15 e 80Hz) e amplitudes de 1 e 2,5mm aplicadas ao tendão calcâneo direito sobre o sistema de controle postural e sobre a circuitaria neural associada a reflexos monosinápticos da perna. A hipótese era de que a vibração de alta freqüência ativasse preferencialmente os aferentes de fuso neuromuscular de tipo Ia enquanto a vibração a 15 Hz ativasse preferencialmente os aferentes de tipo II. Isto significaria que a vibração a 80 Hz teria forte efeito sobre o reflexo H, enquanto a vibração a 15 Hz teria um efeito significativo sobre a postura. Participaram deste estudo 14 sujeitos sãos. Na postura ereta quieta, foi realizada a aquisição do reflexo H enquanto o tendão calcâneo era vibrado. Após um intervalo de descanso, foi realizada a aquisição do Centro de Pressão (COP) tanto na direção Ântero-Posterior (AP) quanto na Médio-Lateral (ML) em paralelo à aquisição bilateral do EMG dos músculos (SO, TA, GL e GM) nas três condições (antes, durante e após a vibração do tendão calcâneo). Para os estímulos de 1 e 2,5mm realizados a 80 Hz as diferenças foram significativas em relação a todas as variáveis quando comparadas nas três condições, com exceção apenas do DP do TA e GM e, do valor médio do COP ML a 1mm. Em relação à freqüência de 15 Hz, notou-se que não houve diferenças significativas tanto no COP AP e ML quanto no DP do EMG dos músculos da perna esquerda entre as três condições. Quanto aos dados referentes ao DP dos músculos analisados na perna direita, os resultados mostraram que não houve efeitos significativos tanto ao utilizar 15Hz como 80Hz em todas as três condições. Em geral, estes dados mostraram que durante um estímulo vibratório mais forte o COP deslocouse mais para a direção posterior e lateral esquerda do sujeito. E, após interromper o estímulo, em alguns casos o COP ainda mostrava uma alteração prolongada. Em relação à amplitude média do reflexo H, para as amplitudes de vibração de 1 e 2,5 mm a 15 e 80 Hz, as análises apontaram que durante a vibração houve uma forte redução na amplitude do reflexo, sendo que em alguns casos ainda permaneceram reduzidas na condição pós-vibratória. Os resultados mostram que a vibração aplicada ao tendão calcâneo pode ser um forte estímulo à medula e capaz de alterar o controle postural, dependendo de suas características, uma vez que, com parâmetros apropriados, induziu alterações imediatas nos resultados do reflexo H, do COP e do EMG (p.e.). Porém, as alterações a vibrações aplicadas de modo a ativar seletivamente as fibras aferentes do grupo Ia e II mostraram efeitos diferenciais. Vibrações a 80Hz de frequência e a 1 e 2,5mm foram as que mais causaram alterações. A significativa ação sobre o reflexo H é compatível com o aumento da frequência de disparos dos aferentes Ia. Entretanto a forte ação sobre o COP dessas vibrações a 80 Hz sugere que os aferentes Ia podem ter uma importância maior do que a literatura recente tem preconizado, pelo menos para correções a perturbações posturais, uma vez que pode-se supor que a 80 Hz e 1 mm de amplitude os aferentes tipo II são pouco ativados. Por outro lado, a vibração a 15 Hz teve um efeito signficativo sobre o reflexo H mas sem afetar o COP, o que sugere que esta frequência consegue ativar a via Ia, causando depressão homossináptica e/ou inibição pré-sináptica dos aferentes Ia, mas sem chegar a influir no COP de forma significativa. Os resultados são interessantes do ponto de vista de aplicações em potencial para áreas como fisioterapia e reabilitação de pessoas com alterações posturais na clínica. Adicionalmente, abrem novas questões quanto às interpretações fisiológicas de vibrações a diferentes freqüências sobre o tendão calcâneo.<br>A vibration applied to a muscle tendon increases the firing frequency of afferents of types Ia and II innervating muscle spindles, and hence affects the spinal cord circuits and this can affect motor control. The aim of this study was to analyze the effect of vibrations of two frequencies (15 and 80Hz) and two amplitudes (1 and 2.5 mm) applied to the right Achilles tendon on the standing posture and on the H reflex. The hypothesis was that the high frequency vibration activates preferentially the Ia axons while the 15 Hz vibration activates preferentially the type II axons and hence the 80 Hz vibration would have a strong effect on the H reflex and the 15 Hz vibration would have a strong effect on posture. Fourteen subjects participated in this study. Their H reflex was acquired in the upright position while their Achilles tendon was vibrated. After an interval of rest, the center of pressure (COP) signal was acquired for both the antero-posterior (AP) and the medio-lateral (ML) directions in parallel with the acquisition of bilateral electromyograms (EMG) (SO, TA, and GL GM) in the three conditions (before, during and after the vibration of the Achilles tendon). For 1 and 2.5 mm vibrations at 80 Hz the differences were significant for all variables compared in the three conditions, except for the standard deviation (SD) of the TA and GM EMGs and the average value of COP ML for 1mm vibration. For the 15 Hz vibration, there were no significant differences in both the AP and ML COP and SD of the EMG of the left leg in the three conditions. The results for the EMG SD of the right leg showed no significant effects when using both 15Hz and 80Hz in all three conditions. These data showed that during a stronger vibratory stimulus the COP shifted more to the posterior direction and the left side of the subject. And, after stopping the stimulus, in some cases, the COP had not returned to the initial position. In relation to the mean H reflex amplitude for 1 and 2.5 mm vibrations at 15 and 80 Hz, the analysis showed that during vibration there was a stronger reduction in the amplitude of the H reflex, and in some cases the amplitude remained reduced in the post-vibratory period. The results showed that the vibration applied to the Achilles tendon can be a powerful stimulus to the spinal cord and capable of altering the postural control. The effects depended on the vibration features, since, with appropriate parameters, it led to immediate changes in the results of the H reflex, the COP and left leg EMG. However, 80 Hz vibration (1 and 2.5 mm) was the one that caused the largest changes both on COP and H reflex amplitude. The significant action on the H reflex is consistent with the increased frequency of firing of Ia afferent. However the strong action on the COP of vibrations at 80 Hz suggests that the Ia afferents may have a greater importance than what the recent literature has suggested, at least for postural corrections to disturbances, since it can be assumed that the type II afferents are little activated at 80 Hz and 1 mm amplitude. Furthermore, vibration at 15 Hz had a significant effect on the H reflex without affecting the COP, suggesting that vibrations at this frequency can activate Ia afferents, causing homosynaptic depression and / or presynaptic inhibition of Ia afferents, but without influencing the COP significantly. The results are interesting from the standpoint of potential applications to areas such as physical therapy and rehabilitation of patients in the clinic. Additionally, they raise new questions about the physiological mechanisms behind vibratory stimuli applied at different frequencies on the Achilles tendon.
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Grünewald, Matthias Lars. "Einfluss des Anästhetikuns Sevofluran und schmerzhafter Stimuli auf den H-Reflex." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=970059256.

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O'Connor, Susan. "How ageing affects identification of the H-reflex in human masseter /." Title page and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09SB/09sbo18.pdf.

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Cameron, Shawn P. "Focal Wrist Cooling Does Not Alter Indices of Spinal Excitability in the Flexor Carpi Radialis Muscle." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1306953575.

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Riedo, Roger. "Origin of the specific H reflex facilitation preceding a voluntary movement in man /." [S.l : s.n.], 1985. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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Martins, Emerson Fachin. "Atividade preparatória de circuitos neuronais medulares durante expectativa para contração muscular voluntária." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-27052008-104200/.

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Antecedendo movimentos voluntariamente gerados, existe atividade neuronal encefálica que se inicia alguns segundos antes da execução deste movimento. Esta atividade preparatória é responsável pela elaboração de um plano de execução que alcança a via final comum para realização de um ato motor voluntário, os motoneurônios. Entretanto, na última década, evidências apontam para a participação de circuitos neuronais na medula espinhal apresentando padrão de atividade similar aos padrões observados em áreas encefálicas e que, possivelmente, estaria relacionado a uma atividade preparatória para o movimento voluntariamente gerado. Por este motivo, o presente trabalho teve por objetivo verificar a atividade de circuitos neuronais na medula espinhal durante diferentes instantes de proximidade da ação voluntariamente gerada em paradigma de tarefa motora com período de instrução. Para isso, inicialmente, 15 sujeitos saudáveis, sem histórico de doença neuromuscular foram submetidos ao protocolo experimental. O protocolo experimental constituiu-se do processo de recrutamento dos sujeitos, sua preparação para o ensaio dentro do ambiente experimental, bem como as orientações necessárias para execução dos procedimentos e paradigmas. Os procedimentos referem-se às etapas realizadas para captação do reflexo H, bem como desta captação sob a influência de técnica de condicionamento por inibição pré-sináptica. Essa captação ocorreu em janelas de aquisição em que o sujeito encontrava-se em repouso e em três instantes de expectativa para a execução de ação voluntária, estando o músculo sóleo atuando como agonista (flexão plantar) ou antagonista (dorsiflexão), em paradigma de tarefa motora voluntária com período de instrução. Após os registros, por meio de processamento dos sinais coletados, foi possível se calcular a amplitude pico-a-pico do reflexo H nas diferentes condições experimentais de proximidade da execução (1000, 600 e 200 milissegundos) e de atuação do músculo sóleo (agonista e antagonista) que foi usado para: (1) análise da variação da excitabilidade reflexa, em porcentagem da onda M máxima, (2) análise da ocorrência de inibição pré-sináptica e (3) análise da variação da inibição pré-sináptica, em porcentagem de inibição. Os resultados mostram que a porcentagem da onda M máxima aumentou significativamente nos três instantes de proximidade com os sujeitos estando em expectativa da execução da tarefa motora quando o músculo sóleo atuaria como agonista da contração, quando comparados com os registros obtidos nas mesmas condições em repouso. Contudo, somente a 200 ms da execução é que foi observado aumento da porcentagem da onda M máxima quando o músculo sóleo atuaria como antagonista. Inibição pré-sináptica ocorreu em todas as condições experimentais, contudo aumento significativo da porcentagem de inibição pré-sináptica foi somente observado a 200 ms da execução da tarefa motora em que o músculo sóleo atuaria como antagonista. Diferenças entre agonista e antagonista com relação ao padrão de excitabilidade reflexa foi somente observado a 600 ms de proximidade da execução da tarefa e essas diferenças com relação à porcentagem de inibição pré-sináptica foi somente detectada a 200 ms. Nossos resultados nos permitem concluir que circuitos neuronais na medula espinhal apresentam atividade no período preparatório para a execução de tarefa motora voluntária que podem estar relacionadas ao comportamento de expectativa da realização de uma ação motora eminente, bem como relacionada ao planejamento motor para a ação a longa proximidade da execução de movimentos.<br>There is brain activity preceding voluntary movements a few seconds before the execution of the movement. This preparatory activity is responsible for the execution plan that reaches the final common pathway, i.e., the motoneurons. In the last decade, there have been reports indicating the involvement of spinal cord circuits in the preparatory activity for movement. The present work has the objective of verifying the activity of spinal cord neuronal circuits at different times preceding a voluntary action, under an instructed delay period paradigm. Fifteen healthy subjects participated in the study. The protocol included an explanation of the experimental tasks. Electrophysiological recordings of the H reflex with and without presynaptic inhibition conditioning were employed. The epochs of H reflex recording were associated either with a resting period or with one of three pre-action periods. The subject received a cue at an appropriate time about the type of contraction: plantarflexion or dorsiflexion. Peak to peak H reflex values were computed in the control resting period and at 1000 ms, 600 ms and 200 ms before the action. Percent values of H amplitude with respect to maximum M values were computed as well as the level of presynaptic inhibition. The results have shown that the relative H reflex value increased significantly at the three premovement times for the soleus under an agonist contraction (i.e., plantarflexion) when compared to control. However, when the soleus was an antagonist to the contraction (i.e., dorsiflexion) there was a statistical difference in the H amplitude only at 200 ms before movement. Presynaptic inhibition occurred in all experimental conditions, however only at 200 ms before contraction there was a significant increase. Differences in reflex excitability between agonist and antagonist activity were only observed at 600 ms before action. On the other hand, differences in presynaptic inhibition were only found at 200 ms before contraction. The results indicated that spinal cord neuronal circuits are activated during the preparatory period preceding a voluntary action. These may be correlated with an expectancy behavior for the execution of an imminent motor action and also with the planning of a motor action at larger times preceding movement execution.
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Books on the topic "H-reflex"

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Gardner, Edward Jonathan. H-reflexes during skilled human voluntary movement. University ofManchester, 1995.

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Sukhamay, Lahiri, and Comroe Julius H. 1911-, eds. Chemoreceptors and reflexes in breathing: Cellular and molecular aspects : the Julius H. Comroe Memorial volume. Oxford University Press, 1989.

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Kerr, Thomas. Relationship between knee joint kinematics and the soleus H reflex during walking. 1998.

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Kiel, Universität, ed. Bewegungen des Sprunggelenkes und reziproke Inhibition: Eine neurophysiologische Studie mit der H-Reflex-Methode. 1993.

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Expressing support for a National Reflex Sympathetic Dystrophy (RSD) Awareness Month: Report (to accompany H. Con. Res. 61) (including cost estimate of the Congressional Budget Office). U.S. G.P.O., 2001.

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Niemann, Niclas. Modulation Konditionierter H-Reflexe Durch Paired Associative Stimulation. GRIN Verlag GmbH, 2016.

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Pitt, Matthew. Nerve physiology. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198754596.003.0003.

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The chapter begins with a description of the normal findings in healthy sensory and motor nerves. The distribution of nerve fibres by diameter in the sensory nerve and its effect on the recorded action potential is outlined. The method by which velocity and compound muscle action potential are derived from motor stimulation follows. H-reflex studies and F-wave identification are described. A section on the strategies used for nerve conduction study in children and the nerves chosen for examination leads on to a description of the difficulties of deriving normative data in children. Next follows a detailed description of the findings in both sensory and motor nerves in demyelination where a distinction between patchy and homogenous demyelination is possible. An analysis of the nerve findings in axonal degeneration is then presented. The chapter finishes with a discussion of the variability in nerve testing.
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A Study of H-Reflexes in Subjects with Acute Ankle Inversion Injuries. Storming Media, 1996.

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Katirji, Bashar. Specialized Electrodiagnostic Studies. Edited by Bashar Katirji. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190603434.003.0003.

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In addition to nerve conduction nerve studies and needle EMG, the clinical EMG study include more specialized examinations Some of the tests, such as the F waves and H reflexes are now often used as part of the routine nerve conduction studies. Others are utilized for specific indications: Repetitive nerve stimulation and single fiber EMG are used predominantly in patients with suspected neuromuscular junction disorders such as myasthenia gravis, Lambert-Eaton myasthenic syndrome or botulism; the blink reflexes are used in patients with disorders of the facial and trigeminal nerves as well as brainstem conditions. This chapter covers the late responses, including the F waves, H reflexes and blink reflexes and their applications in the diagnosis of peripheral nerve disorders. This is a followed by a discussion of the basic concepts of slow and rapid repetitive nerve stimulation and single fiber EMG, as well as their applications in the diagnosis of neuromuscular junction disorders.
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Forster, Chris. Modernism and the Media History of Obscenity. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190840860.003.0002.

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This chapter surveys the history of obscenity in English jurisprudence, from the invention of obscene libel as a crime in the eighteenth century through the 1857 Obscene Publications Act and its 1959 reform. It draws on Marshall McLuhan and Friedrich Kittler to argue that the invention of obscenity, and its subsequent definitions and redefinitions, reflect changes in media ecology and technology. It begins by examining the 1960 trial of D. H. Lawrence’s Lady Chatterley’s Lover, before surveying the history of obscenity, and concluding with readings of the way the technologically mediated character of obscenity is reflected in both James Joyce’s Portrait of the Artist as Young Man and Ian McEwan’s Atonement.
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Book chapters on the topic "H-reflex"

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Jimenez-Dominguez, Ruben, and Volker Milnik. "H-Reflex." In Elektroneurographie und Elektromyographie kompakt. Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-662-63630-5_6.

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Bamford, Jeremy Andrew, and Scott Francis Davis. "The H-Reflex and F-Response." In Principles of Neurophysiological Assessment, Mapping, and Monitoring. Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-8942-9_11.

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Bamford, Jeremy Andrew, and Scott Francis Davis. "The H-Reflex and F-Response." In Principles of Neurophysiological Assessment, Mapping, and Monitoring. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-22400-4_11.

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Thompson, Aiko K., Stephanie D. Pudlik, and Christina R. Thompson. "Effects of H-Reflex Operant Conditioning in Humans." In Converging Clinical and Engineering Research on Neurorehabilitation II. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-46669-9_10.

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Bracchi, F., P. A. Grossi, L. Trovati, and P. Vigano. "H-reflex spinal cord monitoring during vertebral column stabilization surgery." In Handbook of Spinal Cord Monitoring. Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1416-5_36.

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Kitamura, T., T. Nakajima, K. Kamibayashi, S.-I. Yamamoto, M. Akai, and K. Nakazawa. "Effect of passive stepping on the H-reflex in the wrist flexor." In IFMBE Proceedings. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03889-1_54.

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Gerhard, H. "Spinale SEP, F-Welle und H-Reflex in der Diagnostik spinaler Prozesse." In Evozierte Potentiale in Klinik und Praxis. Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-97141-9_9.

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Olyaei, G. R., and R. H. Baxendale. "The Effects of Fatiguing Voluntary Activity on H Reflex Excitability in Man." In Alpha and Gamma Motor Systems. Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1935-5_118.

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Schieppati, M., A. Nardone, and M. Poloni. "Changes in the Normal Pattern of H-Reflex Inhibition During Muscle Release in ALS." In Amyotrophic Lateral Sclerosis. Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-5302-7_26.

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Rimpel, J., M. Rang, S. Meyer, C. Olszak, A. Terwort, and H. J. Lehmann. "H-Reflex-Untersuchung mit konditionierenden Stimuli und Long-latency-Response bei Patienten mit zentralen Paresen." In Verhandlungen der Deutschen Gesellschaft für Neurologie. Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-83771-5_219.

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Conference papers on the topic "H-reflex"

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Paggi, Bernardino, and Marco Feller. "An Alternative and Safer Approach to Takeoff and Landing Acceptable Means of Compliance (AMC/AC 27 and 29) and Air Transport Offshore Operations Regulation." In Vertical Flight Society 74th Annual Forum & Technology Display. The Vertical Flight Society, 2018. http://dx.doi.org/10.4050/f-0074-2018-12877.

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The current certification requirements for multiengine rotorcrafts for takeoff and landing performance do not always provide a safe approach to the scenarios where the helicopters actually operate if compliance demonstration is achieved with the current accepted methods. Several critical aspects of these methods do not to produce "safe" flight envelopes and provide insufficient or inadequate operational information. The current regulations are long dated and not updated to reflect the advance in technology. The current accepted methods of compliance for the definition of the H-V envelope for multi-engine helicopters do not ensure the airworthiness required for all possible operations. For this reasons, the H-V envelope should not be considered a limitation for all CS29 multi-engine configurations and substituted by performance that would allow defining a safer envelope. Particular attention should also be given to operations over elevated helidecks and oilrigs where the environment is extremely demanding and not predictable. In order to get approval for these kinds of operations, specific testing methodology should be developed and approved. A detailed list of proposed changes for the Advisory Circular and applicable regulation is considered and new acceptable compliance methods for the following subjects are proposed for: Cat B Take Off; H-V envelope; Cat A performance for elevated/oilrig helidecks; Takeoff performance influential factors. The incorrect definition of the applicability of the H-V envelope has created an unsafe regulatory case also in the operational rules (AIR-OPS) for Operations in performance class 2 with exposure from helidecks.
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Kojic, Vladimir, Nadica Miljkovic, Nebojsa Malesevic, and Dejan B. Popovic. "H-reflex recorded by multi-pad EMG electrodes." In 2012 11th Symposium on Neural Network Applications in Electrical Engineering (NEUREL 2012). IEEE, 2012. http://dx.doi.org/10.1109/neurel.2012.6419981.

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Cisi, Rogerio R. L., and Andre F. Kohn. "H-reflex depression simulated by a biologically realistic motoneuron network." In 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2007. http://dx.doi.org/10.1109/iembs.2007.4352889.

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Botter, Alberto, Ivan Vazzoler, and Taian M. Vieira. "High density EMG investigation of h-reflex distribution over the soleus muscle." In 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). IEEE, 2015. http://dx.doi.org/10.1109/embc.2015.7319137.

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Hashemi, Seyyedeh Ensiyeh, Mohammad Ali Ahmadi-Pajouh, and Elham Shamsi. "Modeling and Simulation of EMG Signal and H-Reflex in Healthy Human Subject." In 2018 25th National and 3rd International Iranian Conference on Biomedical Engineering (ICBME). IEEE, 2018. http://dx.doi.org/10.1109/icbme.2018.8703535.

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Gao, Ying, Armando Barreto, and Malek Adjouadi. "Comparison of Pupillary Light Reflex Sytem Modeling with H¿ and LSM Adaptive Algorithms." In 2009 IEEE 13th Digital Signal Processing Workshop and 5th IEEE Signal Processing Education Workshop. IEEE, 2009. http://dx.doi.org/10.1109/dsp.2009.4785915.

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Golovinsky, P. M., V. P. Goretsky, A. N. Mosijuk, I. A. Soloshenko, A. F. Tarasenko, and A. I. Tschedrin. "Steady-state production of H− ions by reflex-type Cs free ion source." In Production and neutralization of negative ions and beams. AIP, 1990. http://dx.doi.org/10.1063/1.39612.

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McLinden, John P., Darren E. Gemoets, Daniel Hahn, et al. "Automating visual feedback in H-reflex operant conditioning studies: Feasibility and first steps." In 2023 11th International IEEE/EMBS Conference on Neural Engineering (NER). IEEE, 2023. http://dx.doi.org/10.1109/ner52421.2023.10123817.

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Hashemi, Seyyedeh Ensiyeh, Mohammad Ali Ahmadi-Pajouh, and Elham Shamsi. "Does Motor Imagery Task Alter H-Reflex in FCR Muscle of The Human Hand?" In 2018 25th National and 3rd International Iranian Conference on Biomedical Engineering (ICBME). IEEE, 2018. http://dx.doi.org/10.1109/icbme.2018.8703590.

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Devetzoglou-Toliou, Stavrina, Jodi Brangaccio, Darren E. Gemoets, Andy Borum, Jonathan R. Wolpaw, and James J. S. Norton. "Recursive PID controller for automatically adjusting M-wave size during H-reflex operant conditioning." In 2021 10th International IEEE/EMBS Conference on Neural Engineering (NER). IEEE, 2021. http://dx.doi.org/10.1109/ner49283.2021.9441459.

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Reports on the topic "H-reflex"

1

Stirling, W. L., W. K. Dagenhart, and C. C. Tsai. Volume H/sup -/ generation with the SITEX source in the VITEX reflex mode without cesium. Office of Scientific and Technical Information (OSTI), 1986. http://dx.doi.org/10.2172/5918888.

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Coultas, Mimi. Reforçar os sistemas subnacionais para uma cobertura de saneamento e higiene ao nível das unidades administrativas. Institute of Development Studies, 2022. http://dx.doi.org/10.19088/slh.2022.012.

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De finais de 2020 a princípios de 2021, o Sanitation Learning Hub, (Centro de Aprendizagem de Saneamento [SLH]) colaborou com actores do governo local e parceiros de desenvolvimento de três zonas subnacionais na exploração de formas de fomentar a liderança do governo local e de dar prioridade ao saneamento e higiene (S&amp;H), promovendo o progresso rumo a serviços alargados de S&amp;H à totalidade dessas zonas. Já há algum tempo se tinha reconhecido que a liderança do governo local é essencial para garantir a sustentabilidade e a ampliação da escala e constitui uma componente importante das abordagens emergentes de reforço de sistemas no sector do S&amp;H. Espera-se que este trabalho proporcione experiências práticas que contribuam para esta reflexão. Foram desenvolvidos estudos de caso para captar as experiências do governo local e dos parceiros de desenvolvimento que apoiam os governos subnacionais no fortalecimento da sua liderança e priorização de S&amp;H no distrito de Siaya (no Quénia, com o UNICEF), no distrito de Nyamagabe (no Ruanda, com a WaterAid) e no distrito de Moyo (no Uganda, com a WSSCC), tendo todos eles registado progressos nos últimos anos. Os casos foram então analisados em três workshops com pessoal dos governos locais, os ministérios do governo central e os parceiros de desenvolvimento envolvidos, para rever experiências e identificar alavancas e bloqueios à mudança. Este documento apresenta as principais conclusões deste processo.
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Melloni, Gian. A liderança governamental local em saneamento e higiene: experiências e aprendizagens da África Ocidental. The Sanitation Learning Hub, Institute of Development Studies, 2022. http://dx.doi.org/10.19088/slh.2022.010.

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Entre Julho e Outubro de 2021, o Sanitation Learning Hub (Centro de Aprendizagem do Saneamento) trabalhou com representantes governamentais e parceiros de desenvolvimento, no sentido de desenvolver, partilhar e analisar transversalmente estudos de caso, analisando o sistema local e o reforço do governo em quatro áreas de governo local na África Ocidental: Benim (comuna de N'Dali), Gana (distrito municipal de Yendi), República da Guiné (comuna de Molota), e Nigéria (Área de Governo Local [LGA] de Logo). Esta nota de reflexão divulga as aprendizagens e recomendações que surgiram dos estudos de caso e dos três workshops participativos que se seguiram. Os participantes na iniciativa fizeram uma revisão da primeira versão da presente nota de reflexão. As primeiras secções descrevem as principais partes interessadas e quais as acções do governo local em S&amp;H, enquanto as últimas secções focam os factores de promoção de mudança e obstáculos à mudança, e as recomendações.
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Kennedy, Marie, Aisha Conner-Gaten, Jamie Hazlitt, Javier Garibay, and Marisa Ramirez. Assessing the Diversity of the E-collection of the William H. Hannon Library; a Phased Project. William H. Hannon Library, 2018. http://dx.doi.org/10.15365/whhl.librarian.2018.1022.

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The American Library Association’s 1982 statement on Diversity in Collection Development reminds librarians of our professional responsibility “to select and support the access to materials on all subjects that meet, as closely as possible, the needs, interests, and abilities of all persons in the community the library serves. This includes materials that reflect political, economic, religious, social, minority, and sexual issues.” The William H. Hannon (WHH) Library’s vision statementaffirms that the library views itself as Bridge, Gateway, Agora, and Enterprise. To ensure that our materials collection aligns with our institutional vision and meets the research needs of our diverse campus population, the project team proposed an assessment of our electronic collection through the lens of diversity. The assessment was to determine if the library’s online databases (most often the first point of research consultation for our students and faculty) are adequately “bridging disciplines” (Bridge) and “representing diverse topics and perspectives” (Gateway). What the team learns will inform the library collection strategy, to ensure that it builds collections that deliberately and positively contribute to an inclusive campus climate. [1] http://library.lmu.edu/aboutthelibrary/libraryvisionmission/
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Blais-Stevens, A., A. Castagner, A. Grenier, and K D Brewer. Preliminary results from a subbottom profiling survey of Seton Lake, British Columbia. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/332277.

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Seton Lake is a freshwater fiord located in southwestern British Columbia, roughly 4 km west of Lillooet and 250 km north-northeast of Vancouver. Located in the Coast Mountains, it is an alpine lake about 22-km long and roughly 1-1.5 km wide. It is separated from nearby Anderson Lake, located to the west, by a large pre-historic rock avalanche deposit at Seton Portage. The lake stands at about 243 m above sea level and is up to about 150 m deep (BC gov., 1953). Water level is controlled by a hydroelectric dam (i.e., Seton dam) located at the eastern end of the lake. Here, the lake drains east into Seton Canal, a 5 km diversion of the flow of the Seton River, which begins at the Seton dam. The Seton Canal pushes water to the Seton Powerhouse, a hydroelectric generating station at the Fraser River, just south of the community of Sekw'el'was and confluence of the Seton River, which drains into the Fraser River at Lillooet. Seton Portage, Shalatlh, South Shalatlh, Tsal'alh (Shalath), Sekw'el'was (Cayoosh Creek), and T'it'q'et (Lillooet) are communities that surround the lake. Surrounded by mountainous terrain, the lake is flanked at mid-slope by glacial and colluvial sediments deposited during the last glacial and deglacial periods (Clague, 1989; Jakob, 2018). The bedrock consists mainly of mafic to ultramafic volcanic rocks with minor carbonate and argillite from the Carboniferous to Middle Jurassic periods (Journeay and Monger, 1994). As part of the Public Safety Geoscience Program at the Geological Survey of Canada (Natural Resources Canada), our goal is to provide baseline geoscience information to nearby communities, stakeholders and decision-makers. Our objective was to see what kind of sediments were deposited and specifically if we could identify underwater landslide deposits. Thus, we surveyed the lake using a Pinger SBP sub bottom profiler made by Knudsen Engineering Ltd., with dual 3.5 / 200 kHz transducers mounted to a small boat (see photo). This instrument transmits sound energy down through the water column that reflects off the lake bottom surface and underlying sediment layers. At the lake surface, the reflected sound energy is received by the profiler, recorded on a laptop computer, and integrated with GPS data. These data are processed to generate a two-dimensional image (or profile) showing the character of the lake bottom and underlying sediments along the route that the boat passed over. Our survey in 2022 recorded 98 profiles along Seton Lake. The red transect lines show the locations of the 20 profiles displayed on the poster. The types of sediments observed are mostly fine-grained glaciolacustrine sediments that are horizontally bedded with a subtle transition between glaciolacustrine to lacustrine (e.g., profiles A-A'; C-C'; F-F'; S-S'). Profile S-S' displays this transition zone. The glaciolacustrine sediments probably were deposited as the Cordilleran Ice Sheet retreated from the local area (~13,000-11,000 years ago; Clague, 2017) and the lacustrine sediments, after the ice receded to present-day conditions. Some of the parallel reflections are interrupted, suggesting abrupt sedimentation by deposits that are not horizontally bedded; these are interpreted as landslide deposits (see pink or blue deposits on profiles). The deposits that show disturbance in the sedimentation found within the horizontal beds are thought to be older landslides (e.g., blue arrows/deposits in profiles C-C'; E-E'; F-F'; G-G'; I-I'; J-J'; K-K'; N-N'; P-P'; Q-Q'; R-R'; T-T'; U-U'), but the ones that are found on top of the horizontally laminated sediments (red arrows/pink deposits), and close to the lake wall, are interpreted to be younger (e.g., profiles B-B'; C-C'; H-H'; K-K'; M-M'; O-O'; P-P'; Q-Q'). At the fan delta just west of Seton dam, where there was no acoustic signal penetration, it is interpreted that the delta failed and brought down coarser deposits at the bottom of the lake (e.g., profiles H-H'; M-M'; and perhaps K-K'). However, these could be glacial deposits, bedrock, or other coarser deposits. Some of the deposits that reflect poor penetration of the acoustic signal, below the glaciolacustrine sediments, could represent glacial deposits, old landslide deposits, or perhaps the presence of gas (orange arrows; e.g, B-B'; D-D'; J-J'; O-O', T-T'). The preliminary results from sub bottom profiling reveal that there are underwater landslides deposits of widely varying ages buried in the bottom of the lake. However, the exact timing of these is not known. Hence our preliminary survey gives an overview of the distribution of landslides where there seems to be a larger number of landslides recorded in the narrower eastern portion of the lake.
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