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Sample records for vestibulo-ocular reflex time

  1. Vestibulo-ocular reflex.

    Science.gov (United States)

    Dieterich, M; Brandt, T

    1995-02-01

    Recent animal and clinical studies on the vestibulo-ocular reflex deal with a number of physiological and clinical aspects from which three were chosen for this review: (1) the torsional vestibulo-ocular reflex and its disorders; (2) the otolith contribution to the vestibulo-ocular reflex; and (3) neurotransmitters, neuropharmacological aspects, and medical treatment. Disorders of the vestibulo-ocular reflex can be classified according to the three major planes of action, yaw plane, pitch plane, and roll plane, which equate with horizontal nystagmus, upbeat or downbeat nystagmus, and torsional nystagmus, respectively. The particular interest in the torsional vestibulo-ocular reflex arises from new methods for measuring ocular torsion, especially the three-dimensional eye-movement recordings with scleral coils. These methods make it possible to do three-dimensional analysis of the differential effects of horizontal and vertical semicircular canal function and their individual disorders of the torsional vestibulo-ocular reflex. Otolith and semicircular canal inputs converge at the level of the vestibular nuclei to subserve static graviceptive and dynamic torsional and pitch function. The elaboration of the particular sensorial weight of the input from either the otoliths or the semicircular canal is currently a challenge for both physiologists and neurologists. Disorders of otolith function, still absent from the diagnostic repertoire of most neurologists, are increasingly being reported. The most promising developments in therapeutic measures may come from research on vestibular neurotransmitters, their agonists and antagonists. A number of pharmacological agents are effective suppressants of pathological eye movements. However, systematic prospective studies are needed.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Ontogenetic Development of Vestibulo-Ocular Reflexes in Amphibians.

    Science.gov (United States)

    Branoner, Francisco; Chagnaud, Boris P; Straka, Hans

    2016-01-01

    Vestibulo-ocular reflexes (VOR) ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1-8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets.

  3. Vergence-dependent adaptation of the vestibulo-ocular reflex

    Science.gov (United States)

    Lewis, Richard F.; Clendaniel, Richard A.; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    The gain of the vestibulo-ocular reflex (VOR) normally depends on the distance between the subject and the visual target, but it remains uncertain whether vergence angle can be linked to changes in VOR gain through a process of context-dependent adaptation. In this study, we examined this question with an adaptation paradigm that modified the normal relationship between vergence angle and retinal image motion. Subjects were rotated sinusoidally while they viewed an optokinetic (OKN) stimulus through either diverging or converging prisms. In three subjects the diverging prisms were worn while the OKN stimulus moved out of phase with the head, and the converging prisms were worn when the OKN stimulus moved in-phase with the head. The relationship between the vergence angle and OKN stimulus was reversed in the fourth subject. After 2 h of training, the VOR gain at the two vergence angles changed significantly in all of the subjects, evidenced by the two different VOR gains that could be immediately accessed by switching between the diverged and converged conditions. The results demonstrate that subjects can learn to use vergence angle as the contextual cue that retrieves adaptive changes in the angular VOR.

  4. Role of the flocculus of the cerebellum in motor learning of the vestibulo-ocular reflex

    Science.gov (United States)

    Highstein, S. M.

    1998-01-01

    Structure-function studies at the systems level are an effective method for understanding the relationship of the central nervous system to behavior. Motor learning or adaptation of the vestibulo-ocular reflex is a clear example wherein this approach has been productive. During a vestibulo-ocular reflex the brain converts a head velocity signal, transduced through the vestibular semicircular canals, into an eye movement command delivered to the extraocular muscles. If the viewed target remains on the fovea of the retina, the reflex is compensatory, and its gain, eye velocity/head velocity, is one. When the image of the viewed object slips across the retina, visual acuity decreases, and the gain of the reflex, which is no longer one, is plastically adapted or adjusted until retinal stability is restored. The anatomic substrate for this plasticity thus involves brain structures in which visual-vestibular interaction can potentially occur, as well as vestibular and visual sensory and oculomotor motor structures. Further, it has been known for many years that removal of the flocculus of the cerebellum permanently precludes further vestibulo-ocular reflex adaptation, demonstrating the involvement of the cerebellum in this behavior. Maekawa and Simpson (J Neurophysiol 1973;36: 649-66) discovered that one visual input to the flocculus involved the accessory optic system and the inferior olive. Ensuing work has demonstrated that the visual signals used to adapt the vestibulo-ocular reflex are transmitted by this accessory optic system to the flocculus and subsequently to brain stem structures involved in vestibulo-ocular reflex plasticity. Presently the inclusive list of anatomic sites involved in vestibulo-ocular reflex circuitry and its adaptive plasticity is small. Our laboratory continues to believe that this behavior should be caused by interactions within this small class of neurons. By studying each class of identified neuron and its interactions with others within

  5. Hybrid model of the context dependent vestibulo-ocular reflex: implications for vergence-version interactions

    Science.gov (United States)

    Ranjbaran, Mina; Galiana, Henrietta L.

    2015-01-01

    The vestibulo-ocular reflex (VOR) is an involuntary eye movement evoked by head movements. It is also influenced by viewing distance. This paper presents a hybrid nonlinear bilateral model for the horizontal angular vestibulo-ocular reflex (AVOR) in the dark. The model is based on known interconnections between saccadic burst circuits in the brainstem and ocular premotor areas in the vestibular nuclei during fast and slow phase intervals of nystagmus. We implemented a viable switching strategy for the timing of nystagmus events to allow emulation of real nystagmus data. The performance of the hybrid model is evaluated with simulations, and results are consistent with experimental observations. The hybrid model replicates realistic AVOR nystagmus patterns during sinusoidal or step head rotations in the dark and during interactions with vergence, e.g., fixation distance. By simply assigning proper nonlinear neural computations at the premotor level, the model replicates all reported experimental observations. This work sheds light on potential underlying neural mechanisms driving the context dependent AVOR and explains contradictory results in the literature. Moreover, context-dependent behaviors in more complex motor systems could also rely on local nonlinear neural computations. PMID:25709578

  6. Hybrid Model of the Context Dependent Vestibulo-Ocular Reflex: Implications for Vergence-Version Interactions

    Directory of Open Access Journals (Sweden)

    Mina eRanjbaran

    2015-02-01

    Full Text Available The vestibulo-ocular reflex (VOR is an involuntary eye movement evoked by head movements. It is also influenced by viewing distance. This paper presents a hybrid nonlinear bilateral model for the horizontal angular vestibulo-ocular reflex (AVOR in the dark. The model is based on known interconnections between saccadic burst circuits in the brainstem and ocular premotor areas in the vestibular nuclei during fast and slow phase intervals of nystagmus. We implemented a viable switching strategy for the timing of nystagmus events to allow emulation of real nystagmus data. The performance of the hybrid model is evaluated with simulations, and results are consistent with experimental observations. The hybrid model replicates realistic AVOR nystagmus patterns during sinusoidal or step head rotations in the dark and during interactions with vergence, e.g. fixation distance. By simply assigning proper nonlinear neural computations at the premotor level, the model replicates all reported experimental observations. This work sheds light on potential underlying neural mechanisms driving the context dependent AVOR and explains contradictory results in the literature. Moreover, context-dependent behaviors in more complex motor systems could also rely on local nonlinear neural computations.

  7. Phase changes induced by ketamine in the vertical vestibulo-ocular reflex in the rabbit.

    Science.gov (United States)

    Favilla, M; Ghelarducci, B; La Noce, A; Starita, A

    1981-11-09

    The effect of ketamine has been tested on the phase of the vertical vestibulo-ocular reflex of rabbits sinusoidally oscillated at various frequencies. A significant phase lag, predominantly affecting the macular component of the reflex, was observed. This action resembles that induced by Nembutal in the same preparation. A specific action of ketamine on synaptic transmission is suggested. Erroneous phase relationship between natural stimuli responses can be obtained in experiments employing ketamine.

  8. DVA as a Diagnostic Test for Vestibulo-Ocular Reflex Function

    Science.gov (United States)

    Wood, Scott J.; Appelbaum, Meghan

    2010-01-01

    The vestibulo-ocular reflex (VOR) stabilizes vision on earth-fixed targets by eliciting eyes movements in response to changes in head position. How well the eyes perform this task can be functionally measured by the dynamic visual acuity (DVA) test. We designed a passive, horizontal DVA test to specifically study the acuity and reaction time when looking in different target locations. Visual acuity was compared among 12 subjects using a standard Landolt C wall chart, a computerized static (no rotation) acuity test and dynamic acuity test while oscillating at 0.8 Hz (+/-60 deg/s). In addition, five trials with yaw oscillation randomly presented a visual target in one of nine different locations with the size and presentation duration of the visual target varying across trials. The results showed a significant difference between the static and dynamic threshold acuities as well as a significant difference between the visual targets presented in the horizontal plane versus those in the vertical plane when comparing accuracy of vision and reaction time of the response. Visual acuity increased proportional to the size of the visual target and increased between 150 and 300 msec duration. We conclude that dynamic visual acuity varies with target location, with acuity optimized for targets in the plane of rotation. This DVA test could be used as a functional diagnostic test for visual-vestibular and neuro-cognitive impairments by assessing both accuracy and reaction time to acquire visual targets.

  9. Latency of cross-axis vestibulo-ocular reflex induced by pursuit training in monkeys.

    Science.gov (United States)

    Sato, T; Yokoyama, R; Fukushima, J; Fukushima, K

    1999-01-01

    To examine the latency of smooth pursuit induced, short-term modifications of the vestibulo-ocular reflex (VOR), Japanese monkeys were rewarded for tracking a vertically moving target spot synchronized with horizontal whole body rotation. Eye movements induced by equivalent rotation in complete darkness were examined before and after training. Before training, the horizontal trapezoidal rotation (peak acceleration approximately 78%/s2) resulted in a collinear VOR with a mean latency of 15.3 ms, and no orthogonal component in any of the three monkeys tested. After training, the collinear VOR remained unchanged but an orthogonal, cross-axis VOR developed. It had a mean latency of 42.4 ms with gain (eye/chair) of 0.19, followed by a decaying phase that had a mean time constant of 80 ms. These results suggest that the cross-axis VOR induced by pursuit-vestibular interaction is different from previously reported cross-axis VOR induced by optokinetic-vestibular interaction.

  10. Artificial balance: restoration of the vestibulo-ocular reflex in humans with a prototype vestibular neuroprosthesis.

    Science.gov (United States)

    Perez Fornos, Angelica; Guinand, Nils; van de Berg, Raymond; Stokroos, Robert; Micera, Silvestro; Kingma, Herman; Pelizzone, Marco; Guyot, Jean-Philippe

    2014-01-01

    The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently, there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the vestibulo-ocular reflex (VOR), the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss.

  11. Artificial balance: restoration of the vestibulo-ocular reflex in humans with a prototype vestibular neuroprosthesis

    Directory of Open Access Journals (Sweden)

    Angelica ePerez Fornos

    2014-04-01

    Full Text Available The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the Vestibulo-Ocular Reflex (VOR, the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss.

  12. Vestibulo-ocular reflex modification after virtual environment exposure.

    Science.gov (United States)

    Di Girolamo, S; Picciotti, P; Sergi, B; Di Nardo, W; Paludetti, G; Ottaviani, F

    2001-01-01

    Immersion in an illusory world is possible by means of virtual reality (VR), where environmental perception is modified by artificial sensorial stimulation. The application of VR for the assessment and rehabilitation of pathologies affecting the vestibular system, in terms of both diagnosis and care, could represent an interesting new line of research. Our perception of reality is in fact based on static and dynamic spatial information perceived by our senses. During head movements in a virtual environment the images on the display and the labyrinthine information relative to the head angular accelerations differ and therefore a visuo-vestibular conflict is present. It is known that mismatches between visual and labyrinthine information may modify the vestibulo-oculomotor reflex (VOR) gain. We studied the post-immersion modifications in 20 healthy subjects (mean age 25 years) exposed to a virtual environment for 20 min by wearing a head-mounted display. VOR gain and phase were measured by means of harmonic sinusoidal stimulation in the dark before, at the end of and 30 min after VR exposure. A VOR gain reduction was observed in all subjects at the end of VR exposure which disappeared after 30 min. Our data show that exposure to a virtual environment can induce a temporary modification of the VOR gain. This finding can be employed to enable an artificial, instrumental modification of the VOR gain and therefore opens up new perspectives in the assessment and rehabilitation of vestibular diseases.

  13. Strength of baseline inter-trial correlations forecasts adaptive capacity in the vestibulo-ocular reflex.

    Directory of Open Access Journals (Sweden)

    Kara H Beaton

    Full Text Available Individual differences in sensorimotor adaptability may permit customized training protocols for optimum learning. Here, we sought to forecast individual adaptive capabilities in the vestibulo-ocular reflex (VOR. Subjects performed 400 head-rotation steps (400 trials during a baseline test, followed by 20 min of VOR gain adaptation. All subjects exhibited mean baseline VOR gain of approximately 1.0, variable from trial to trial, and showed desired reductions in gain following adaptation with variation in extent across individuals. The extent to which a given subject adapted was inversely proportional to a measure of the strength and duration of baseline inter-trial correlations (β. β is derived from the decay of the autocorrelation of the sequence of VOR gains, and describes how strongly correlated are past gain values; it thus indicates how much the VOR gain on any given trial is informed by performance on previous trials. To maximize the time that images are stabilized on the retina, the VOR should maintain a gain close to 1.0 that is adjusted predominantly according to the most recent error; hence, it is not surprising that individuals who exhibit smaller β (weaker inter-trial correlations also exhibited the best adaptation. Our finding suggests that the temporal structure of baseline behavioral data contains important information that may aid in forecasting adaptive capacities. This has significant implications for the development of personalized physical therapy protocols for patients, and for other cases when it is necessary to adjust motor programs to maintain movement accuracy in response to pathological and environmental changes.

  14. The horizontal angular vestibulo-ocular reflex: a nonlinear mechanism for context-dependent responses.

    Science.gov (United States)

    Ranjbaran, Mina; Galiana, Henrietta L

    2013-11-01

    Studies of the vestibulo-ocular reflex (VOR) have revealed that this type of involuntary eye movement is influenced by viewing distance. This paper presents a bilateral model for the horizontal angular VOR in the dark based on realistic physiological mechanisms. It is shown that by assigning proper nonlinear neural computations at the premotor level, the model is capable of replicating target-distance-dependent VOR responses that are in agreement with geometrical requirements. Central premotor responses in the model are also shown to be consistent with experimental observations. Moreover, the model performance after simulated unilateral canal plugging also reproduces experimental observations, an emerging property. Such local nonlinear computations could similarly generate context-dependent behaviors in other more complex motor systems.

  15. Inaccurate Saccades and Enhanced Vestibulo-Ocular Reflex Suppression during Combined Eye–Head Movements in Patients with Chronic Neck Pain: Possible Implications for Cervical Vertigo

    National Research Council Canada - National Science Library

    Johnston, Janine L; Daye, Pierre M; Thomson, Glen T. D

    2017-01-01

    .... The vestibulo-ocular reflex (VOR) is greatly reduced at the onset of large eye–head (gaze) saccades and resumes before the end of the saccades to stabilize eye-in-orbit and ensure accurate target acquisition...

  16. Ontogeny of mouse vestibulo-ocular reflex following genetic or environmental alteration of gravity sensing.

    Directory of Open Access Journals (Sweden)

    Mathieu Beraneck

    Full Text Available The vestibular organs consist of complementary sensors: the semicircular canals detect rotations while the otoliths detect linear accelerations, including the constant pull of gravity. Several fundamental questions remain on how the vestibular system would develop and/or adapt to prolonged changes in gravity such as during long-term space journey. How do vestibular reflexes develop if the appropriate assembly of otoliths and semi-circular canals is perturbed? The aim of present work was to evaluate the role of gravity sensing during ontogeny of the vestibular system. In otoconia-deficient mice (ied, gravity cannot be sensed and therefore maculo-ocular reflexes (MOR were absent. While canals-related reflexes were present, the ied deficit also led to the abnormal spatial tuning of the horizontal angular canal-related VOR. To identify putative otolith-related critical periods, normal C57Bl/6J mice were subjected to 2G hypergravity by chronic centrifugation during different periods of development or adulthood (Adult-HG and compared to non-centrifuged (control C57Bl/6J mice. Mice exposed to hypergravity during development had completely normal vestibulo-ocular reflexes 6 months after end of centrifugation. Adult-HG mice all displayed major abnormalities in maculo-ocular reflexe one month after return to normal gravity. During the next 5 months, adaptation to normal gravity occurred in half of the individuals. In summary, genetic suppression of gravity sensing indicated that otolith-related signals might be necessary to ensure proper functioning of canal-related vestibular reflexes. On the other hand, exposure to hypergravity during development was not sufficient to modify durably motor behaviour. Hence, 2G centrifugation during development revealed no otolith-specific critical period.

  17. Ontogeny of mouse vestibulo-ocular reflex following genetic or environmental alteration of gravity sensing.

    Science.gov (United States)

    Beraneck, Mathieu; Bojados, Mickael; Le Séac'h, Anne; Jamon, Marc; Vidal, Pierre-Paul

    2012-01-01

    The vestibular organs consist of complementary sensors: the semicircular canals detect rotations while the otoliths detect linear accelerations, including the constant pull of gravity. Several fundamental questions remain on how the vestibular system would develop and/or adapt to prolonged changes in gravity such as during long-term space journey. How do vestibular reflexes develop if the appropriate assembly of otoliths and semi-circular canals is perturbed? The aim of present work was to evaluate the role of gravity sensing during ontogeny of the vestibular system. In otoconia-deficient mice (ied), gravity cannot be sensed and therefore maculo-ocular reflexes (MOR) were absent. While canals-related reflexes were present, the ied deficit also led to the abnormal spatial tuning of the horizontal angular canal-related VOR. To identify putative otolith-related critical periods, normal C57Bl/6J mice were subjected to 2G hypergravity by chronic centrifugation during different periods of development or adulthood (Adult-HG) and compared to non-centrifuged (control) C57Bl/6J mice. Mice exposed to hypergravity during development had completely normal vestibulo-ocular reflexes 6 months after end of centrifugation. Adult-HG mice all displayed major abnormalities in maculo-ocular reflexe one month after return to normal gravity. During the next 5 months, adaptation to normal gravity occurred in half of the individuals. In summary, genetic suppression of gravity sensing indicated that otolith-related signals might be necessary to ensure proper functioning of canal-related vestibular reflexes. On the other hand, exposure to hypergravity during development was not sufficient to modify durably motor behaviour. Hence, 2G centrifugation during development revealed no otolith-specific critical period.

  18. Effect of vergence on the gain of the linear vestibulo-ocular reflex

    Science.gov (United States)

    Shelhamer, M.; Merfeld, D. M.; Mendoza, J. C.; Paloski, W. H. (Principal Investigator)

    1995-01-01

    We measured the linear vestibulo-ocular reflex (LVOR) and vergence, using binocular search coils, in 3 humans. The subjects were accelerated sinusoidally at 0.5 Hz and 0.2 g peak acceleration, in complete darkness, while performing three different tasks: i) mental arithmetic; ii) tracking a remembered target at either 0.34 m or 0.14 m distance; and iii) maintaining vergence at either of these distances by means of audio biofeedback based on vergence. Subjects could control vergence using the audio feedback; there was greater convergence with the near audio target. However, there was no significant difference in vergence between the near and far remembered target conditions. With audio feedback, the amplitude of smooth tracking was not consistently different for the near and the far conditions. However, the amplitude of tracking (saccades and smooth component) in the remembered target conditions was greater for near than for far targets. These results suggest that linear VOR amplitude is not determined by vergence alone.

  19. The vestibular implant: frequency-dependency of the electrically evoked vestibulo-ocular reflex in humans.

    Science.gov (United States)

    van de Berg, Raymond; Guinand, Nils; Nguyen, T A Khoa; Ranieri, Maurizio; Cavuscens, Samuel; Guyot, Jean-Philippe; Stokroos, Robert; Kingma, Herman; Perez-Fornos, Angelica

    2014-01-01

    The vestibulo-ocular reflex (VOR) shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR) elicited by a vestibular implant, showed the same frequency-dependency. Twelve vestibular electrodes implanted in seven patients with bilateral vestibular hypofunction (BVH) were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5, 1, and 2 Hz. The main characteristics of the eVOR were evaluated and compared to the "natural" VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies. A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the "natural" VOR. Other characteristics of the (e)VOR (angle, habituation-index, and asymmetry) showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited) frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the "normal" vestibular system.

  20. Adaptation of the vertical vestibulo-ocular reflex in cats during low-frequency vertical rotation.

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    Fushiki, Hiroaki; Maruyama, Motoyoshi; Shojaku, Hideo

    2017-04-27

    We examined plastic changes in the vestibulo-ocular reflex (VOR) during low-frequency vertical head rotation, a condition under which otolith inputs from the vestibular system are essential for VOR generation. For adaptive conditioning of the vertical VOR, 0.02Hz sinusoidal pitch rotation for one hour about the earth's horizontal axis was synchronized with out-of-phase vertical visual stimulation from a random dot pattern. A vertical VOR was well evoked when the upright animal rotated around the earth-horizontal axis (EHA) at low frequency due to the changing gravity stimulus and dynamic stimulation of the otoliths. After adaptive conditioning, the amplitude of the vertical VOR increased by an average of 32.1%. Our observations showing plasticity in the otolithic contribution to the VOR may provide a new strategy for visual-vestibular mismatch training in patients with otolithic disorders. This low-frequency vertical head rotation protocol also provides a model for investigating the mechanisms underlying the adaptation of VORs mediated by otolith activation. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Single motor unit activity in human extraocular muscles during the vestibulo-ocular reflex

    Science.gov (United States)

    Weber, Konrad P; Rosengren, Sally M; Michels, Rike; Sturm, Veit; Straumann, Dominik; Landau, Klara

    2012-01-01

    Motor unit activity in human eye muscles during the vestibulo-ocular reflex (VOR) is not well understood, since the associated head and eye movements normally preclude single unit recordings. Therefore we recorded single motor unit activity following bursts of skull vibration and sound, two vestibular otolith stimuli that elicit only small head and eye movements. Inferior oblique (IO) and inferior rectus (IR) muscle activity was measured in healthy humans with concentric needle electrodes. Vibration elicited highly synchronous, short-latency bursts of motor unit activity in the IO (latency: 10.5 ms) and IR (14.5 ms) muscles. The activation patterns of the two muscles were similar, but reciprocal, with delayed activation of the IR muscle. Sound produced short-latency excitation of the IO muscle (13.3 ms) in the eye contralateral to the stimulus. Simultaneous needle and surface recordings identified the IO as the muscle of origin of the vestibular evoked myogenic potential (oVEMP) thus validating the physiological basis of this recently developed clinical test of otolith function. Single extraocular motor unit recordings provide a window into neural activity in humans that can normally only be examined using animal models and help identify the pathways of the translational VOR from otoliths to individual eye muscles. PMID:22526888

  2. The vestibular implant: Frequency-dependency of the electrically evoked Vestibulo-Ocular Reflex in humans

    Directory of Open Access Journals (Sweden)

    Raymond eVan De Berg

    2015-01-01

    Full Text Available The Vestibulo-Ocular Reflex (VOR shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR elicited by a vestibular implant, showed the same frequency-dependency.Twelve vestibular electrodes implanted in 7 patients with bilateral vestibular hypofunction were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5Hz, 1Hz, and 2Hz. The main characteristics of the eVOR were evaluated and compared to the natural VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies.A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the natural VOR. Other characteristics of the (eVOR (angle, habituation-index, and asymmetry showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the normal vestibular system.

  3. Combined action of smooth pursuit eye movements, optokinetic reflex and vestibulo-ocular reflex in macaque monkey during transient stimulation.

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    Schweigart, G; Maurer, C; Mergner, T

    2003-04-17

    The interaction of smooth pursuit eye movements, vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) is still not well understood. We therefore measured in macaque monkeys horizontal eye movements using transient horizontal rotations of a visual target, of monkeys' heads and/or of an optokinetic background pattern (ten combinations; smoothed position ramps of 16 degrees ). With intermediate peak velocity of target motion (v(max)=12.8 degrees /s), pursuit held the eyes rather well on target, almost independent of concurrent vestibular or optokinetic stimuli (pursuit gain, 0.73-0.91). With v(max)=1.6 degrees /s, in contrast, pursuit gain became strongly modified by the optokinetic stimulus. With v(max)=51.2 degrees /s, pursuit gain became modified by vestibular stimulation. Although not intuitive, the experimental data can be explained by linear interaction (summation) of the neural driving signals for pursuit, VOR and OKR, as ascertained by simulations of a dynamic model.

  4. Translational Vestibulo-Ocular Reflexes During Off-Vertical Axis Rotation

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    Wood, Scott J.; Clement, Gilles

    2009-01-01

    The translational vestibulo-ocular reflex (tVOR) is an otolith-mediated response that stabilizes near vision during linear acceleration at higher frequencies where visually mediated reflexes are not adequate. The modulation of horizontal and vergence eye movements during Off-Vertical Axis Rotation (OVAR) are presumed to reflect the tVOR in response to the continuously varying linear acceleration in the interaural and nasooccipital axes, respectively. The purpose of this study was to examine the effect of frequency and fixation distance on the modulation of slow phase eye velocity (SPV) as further evidence that the tVOR is elicited during OVAR. Eighteen subjects were rotated about their longitudinal axis tilted by 30 deg off-vertical. Rotational velocities varied between 18 and 288 deg/sec corresponding to a frequency range of 0.05 to 0.8 Hz. Fixation distance was altered by asking subjects to imagine stationary targets that were briefly presented at 0.5, 1 and 2 m during some rotation cycles. The target flash was 40 msec in the nose-up position at eye level. Oculomotor responses were recorded in the dark using infrared binocular videography. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple rotation cycles. Consistent with previous studies, the modulation of both horizontal and vergence SPV increased with stimulus frequency. The effect of fixation distance was negligible at lower frequencies. The modulation of horizontal and vergence SPV was; however, proportional to fixation distance during OVAR at 0.8 Hz. This increasing sensitivity and dependence on fixation distance of horizontal and vergence SPV during OVAR is consistent with tVOR characteristics measured during other types of linear motion. We conclude that the modulation of horizontal and vergence SPV will be diagnostically more useful at higher stimulus frequencies where the tVOR is more robust.

  5. The cerebellar nodulus/uvula integrates otolith signals for the translational vestibulo-ocular reflex.

    Directory of Open Access Journals (Sweden)

    Mark F Walker

    2010-11-01

    Full Text Available The otolith-driven translational vestibulo-ocular reflex (tVOR generates compensatory eye movements to linear head accelerations. Studies in humans indicate that the cerebellum plays a critical role in the neural control of the tVOR, but little is known about mechanisms of this control or the functions of specific cerebellar structures. Here, we chose to investigate the contribution of the nodulus and uvula, which have been shown by prior studies to be involved in the processing of otolith signals in other contexts.We recorded eye movements in two rhesus monkeys during steps of linear motion along the interaural axis before and after surgical lesions of the cerebellar uvula and nodulus. The lesions strikingly reduced eye velocity during constant-velocity motion but had only a small effect on the response to initial head acceleration. We fit eye velocity to a linear combination of head acceleration and velocity and to a dynamic mathematical model of the tVOR that incorporated a specific integrator of head acceleration. Based on parameter optimization, the lesion decreased the gain of the pathway containing this new integrator by 62%. The component of eye velocity that depended directly on head acceleration changed little (gain decrease of 13%. In a final set of simulations, we compared our data to the predictions of previous models of the tVOR, none of which could account for our experimental findings.Our results provide new and important information regarding the neural control of the tVOR. Specifically, they point to a key role for the cerebellar nodulus and uvula in the mathematical integration of afferent linear head acceleration signals. This function is likely to be critical not only for the tVOR but also for the otolith-mediated reflexes that control posture and balance.

  6. The conjugacy of the vestibulo-ocular reflex evoked by single labyrinth stimulation in awake monkeys.

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    Tang, Xuehui; Xu, Youguo; Simpson, Ivra; Jeffcoat, Ben; Mustain, William; Zhou, Wu

    2010-10-01

    It is well known that the vestibulo-ocular reflex (VOR) is conjugate when measured in the dark with minimal vergence. But the neural basis of the VOR conjugacy remains to be identified. In the present study, we measured the VOR conjugacy during single labyrinth stimulation to examine whether the VOR conjugacy depends on reciprocal stimulation of the two labyrinths. There are conflicting views on this issue. First, since the vestibular signals carried by the ascending tract of Deiters' are distributed exclusively to the motoneurons of the ipsilateral eye, the neural innervations after single labyrinth stimulation are not symmetrical for the two eyes. Thus, single labyrinth stimulation may generate disjunctive VOR responses. Second, the only published study on this issue was an electrooculography (EOG) study that reported disjunctive VOR responses during unilateral caloric irrigation (Wolfe in Ann Otol 88:79-85, 1979). Third, the VOR during unilateral caloric stimulation performed in clinical vestibular tests is routinely perceived to be conjugate. To resolve these conflicting views, the present study examined the VOR conjugacy during single labyrinth stimulation by recording binocular eye position signals in awake monkeys with a search coil technique. In contradiction to the previous EOG study and the prediction based on the asymmetry of the unilateral brainstem VOR circuits, we found that the VOR during unilateral caloric irrigation was conjugate over a wide range of conditions. We conclude that the net neural innervations received by the two eyes are symmetrical after single labyrinth stimulation, despite the apparent asymmetry in the unilateral VOR pathways. A novel role for the ascending tract of Deiters' in the VOR conjugacy is proposed.

  7. Epidemiology of vestibulo-ocular reflex function: data from the Baltimore Longitudinal Study of Aging.

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    Li, Carol; Layman, Andrew J; Geary, Robert; Anson, Eric; Carey, John P; Ferrucci, Luigi; Agrawal, Yuri

    2015-02-01

    To determine age-related changes in vestibulo-ocular reflex (VOR) function in community-dwelling adults, and evaluate these for associations with demographic characteristics and cardiovascular risk factors. Cross-sectional analysis within the Baltimore Longitudinal Study of Aging (BLSA), a longitudinal prospective cohort study. Vestibular testing laboratory within an acute care teaching hospital. Community-dwelling adults enrolled in the BLSA. Horizontal VOR gain measurement using video head-impulse testing and visual acuity testing. VOR gain was calculated as the ratio of eye velocity to head velocity. Demographic and cardiovascular risk factor data were collected through study questionnaires. One hundred nine subjects were analyzed with mean age (SD) 69.9 years (14.2), with a range from 26 to 92 years. VOR gain remained stable from age 26 to 79 after which it significantly declined at a rate of 0.012/year (p = 0.033) in adjusted analyses. Individuals aged 80 years or older had a nearly 8-fold increased odds of VOR gain less than 0.80 relative to those aged less than 80 years in multivariate models (prevalence of 13.2% vs. 2.8%; OR 7.79, 95% CI: 1.04-58.38). Otherwise, VOR gain did not differ significantly across demographic or cardiovascular risk groups. We report age-related decline in VOR function in individuals aged 80 years and older. Further analyses are in progress to establish the significance of these VOR abnormalities to functional and mobility outcomes in older individuals.

  8. Getting ahead of oneself: anticipation and the vestibulo-ocular reflex.

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    King, W M

    2013-04-16

    Compensatory counter-rotations of the eyes provoked by head turns are commonly attributed to the vestibulo-ocular reflex (VOR). A recent study in guinea pigs demonstrates, however, that this assumption is not always valid. During voluntary head turns, guinea pigs make highly accurate compensatory eye movements that occur with zero or even negative latencies with respect to the onset of the provoking head movements. Furthermore, the anticipatory eye movements occur in animals with bilateral peripheral vestibular lesions, thus confirming that they have an extra vestibular origin. This discovery suggests the possibility that anticipatory responses might also occur in other species including humans and non-human primates, but have been overlooked and mistakenly identified as being produced by the VOR. This review will compare primate and guinea pig vestibular physiology in light of these new findings. A unified model of vestibular and cerebellar pathways will be presented that is consistent with current data in primates and guinea pigs. The model is capable of accurately simulating compensatory eye movements to active head turns (anticipatory responses) and to passive head perturbations (VOR induced eye movements) in guinea pigs and in human subjects who use coordinated eye and head movements to shift gaze direction in space. Anticipatory responses provide new evidence and opportunities to study the role of extra vestibular signals in motor control and sensory-motor transformations. Exercises that employ voluntary head turns are frequently used to improve visual stability in patients with vestibular hypofunction. Thus, a deeper understanding of the origin and physiology of anticipatory responses could suggest new translational approaches to rehabilitative training of patients with bilateral vestibular loss. Copyright © 2013. Published by Elsevier Ltd.

  9. Readaptation of the Vestibulo-Ocular Reflex Relieves the Mal de Debarquement Syndrome

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    Mingjia eDai

    2014-07-01

    Full Text Available The Mal de Debarquement Syndrome (MdDS, a continuous feeling of swaying, rocking and/or bobbing, generally follows travel on the sea. The associated symptoms cause considerable distress. The underlying neural mechanisms are unknown, and to date there have been no effective treatments for this condition. Results in monkeys and humans suggested that MdDS was caused by maladaptation of the vestibulo-ocular reflex (VOR to roll of the head during rotation. We studied twenty-four subjects with persistent MdDS (3 males, 21 females; 19.1 ± 33 months. Physical findings included body oscillation at 0.2Hz, oscillating vertical nystagmus when the head was rolled from side-to-side in darkness, and unilateral rotation during the Fukuda stepping test. We posited that the maladapted rocking and the physical symptoms could be diminished or extinguished by readapting the VOR. Subjects were treated by rolling the head from side-to-side while watching a rotating full-field visual stimulus. Seventeen of the twenty-four subjects had a complete or substantial recovery on average for approximately one year. Six were initially better, but the symptoms recurred. One subject did not respond to treatment. Thus, readaptation of the VOR has led to a cure or substantial improvement in 70% of the subjects with MdDS. We conclude that the adaptive processes associated with roll-while-rotating are responsible for producing MdDS, and that the symptoms can be reduced or resolved by readapting the VOR.

  10. Readaptation of the vestibulo-ocular reflex relieves the mal de debarquement syndrome.

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    Dai, Mingjia; Cohen, Bernard; Smouha, Eric; Cho, Catherine

    2014-01-01

    The mal de debarquement syndrome (MdDS), a continuous feeling of swaying, rocking, and/or bobbing, generally follows travel on the sea. The associated symptoms cause considerable distress. The underlying neural mechanisms are unknown, and to date there have been no effective treatments for this condition. Results in monkeys and humans suggested that MdDS was caused by maladaptation of the vestibulo-ocular reflex (VOR) to roll of the head during rotation. We studied 24 subjects with persistent MdDS (3 males, 21 females; 19.1 ± 33 months). Physical findings included body oscillation at 0.2 Hz, oscillating vertical nystagmus when the head was rolled from side-to-side in darkness, and unilateral rotation during the Fukuda stepping test. We posited that the maladapted rocking and the physical symptoms could be diminished or extinguished by readapting the VOR. Subjects were treated by rolling the head from side-to-side while watching a rotating full-field visual stimulus. Seventeen of the 24 subjects had a complete or substantial recovery on average for approximately 1 year. Six were initially better, but the symptoms recurred. One subject did not respond to treatment. Thus, readaptation of the VOR has led to a cure or substantial improvement in 70% of the subjects with MdDS. We conclude that the adaptive processes associated with roll-while-rotating are responsible for producing MdDS, and that the symptoms can be reduced or resolved by readapting the VOR.

  11. Signal processing related to the vestibulo-ocular reflex during combined angular rotation and linear translation of the head

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    McCrea, R. A.; Chen-Huang, C.; Peterson, B. W. (Principal Investigator)

    1999-01-01

    The contributions of vestibular nerve afferents and central vestibular pathways to the angular (AVOR) and linear (LVOR) vestibulo-ocular reflex were studied in squirrel monkeys during fixation of near and far targets. Irregular vestibular afferents did not appear to be necessary for the LVOR, since when they were selectively silenced with galvanic currents the LVOR was essentially unaffected during both far- and near-target viewing. The linear translation signals generated by secondary AVOR neurons in the vestibular nuclei were, on average, in phase with head velocity, inversely related to viewing distance, and were nearly as strong as AVOR-related signals. We suggest that spatial-temporal transformation of linear head translation signals to angular eye velocity commands is accomplished primarily by the addition of viewing distance multiplied, centrally integrated, otolith regular afferent signals to angular VOR pathways.

  12. A biophysical approach to the spatial function of eye movements, extraocular proprioception and the vestibulo-ocular reflex.

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    Daunicht, W J

    1988-01-01

    The eyeball and the extraocular muscles are used as a paradigm to design a linear spatial model of a single joint with a redundant set of muscles. On the basis of this model relations are derived between orientation, torque, motor commands, and proprioceptive signals. These relations show that the tenet underlying the tensorial interpretation of neural signals in sensorimotor systems does not have general validity. A mechanism is proposed to show how proprioception may play a role in optimizing the coordination of muscles during spatial tasks. Further, a new concept is suggested that allows one to predict the neural connectivities mediating the redundant spatial vestibulo-ocular reflex. This concept has the advantage of minimizing both sensorial error and motor effort.

  13. Ethanol consumption impairs vestibulo-ocular reflex function measured by the video head impulse test and dynamic visual acuity.

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    Roth, Thomas N; Weber, Konrad P; Wettstein, Vincent G; Marks, Guy B; Rosengren, Sally M; Hegemann, Stefan C A

    2014-01-01

    Ethanol affects many parts of the nervous system, from the periphery to higher cognitive functions. Due to the established effects of ethanol on vestibular and oculomotor function, we wished to examine its effect on two new tests of the vestibulo-ocular reflex (VOR): the video head impulse test (vHIT) and dynamic visual acuity (DVA). We tested eight healthy subjects with no history of vestibular disease after consumption of standardized drinks of 40% ethanol. We used a repeated measures design to track vestibular function over multiple rounds of ethanol consumption up to a maximum breath alcohol concentration (BrAC) of 1.38 per mil. All tests were normal at baseline. VOR gain measured by vHIT decreased by 25% at the highest BrAC level tested in each subject. Catch-up saccades were negligible at baseline and increased in number and size with increasing ethanol consumption (from 0.13° to 1.43° cumulative amplitude per trial). DVA scores increased by 86% indicating a deterioration of acuity, while static visual acuity (SVA) remained unchanged. Ethanol consumption systematically impaired the VOR evoked by high-acceleration head impulses and led to a functional loss of visual acuity during head movement.

  14. Interaction of linear and angular vestibulo-ocular reflexes of human subjects in response to transient motion.

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    Anastasopoulos, D; Gianna, C C; Bronstein, A M; Gresty, M A

    1996-08-01

    The possibility of synergistic interaction between the canal and otolith components of the horizontal vestibulo-ocular reflex (VOR) was evaluated in human subjects by subtracting the response to pure angular rotation (AVOR) from the response to combined angular and translational motion (ALVOR) and comparing this difference with the VOR to isolated linear motion (LVOR). Assessments were made with target fixation at 60 cm and in darkness. Linear stimuli were acceleration steps attaining 0.25 g in less than 80 ms. To elicit responses to combined translational and angular head movements, the subjects were seated on a Barany chair with the head displaced forwards 40 cm from the axis of rotation. The chair was accelerated at approximately 300 deg/s2 to 127 deg/s peak angular velocity, the tangential acceleration of the head being comparable with that of isolated translation. Estimates of the contribution of smooth pursuit to responses in the light were made from comparisons of isolated pursuit of similar target trajectories. In the dark the slow phase eye movements evoked by combined canal-otolith stimuli were higher in magnitude by approximately a third than the sum of those produced by translation and rotation alone. In the light, the relative target displacement during isolated linear motion was similar to the difference in relative target displacements during eccentric and centred rotation. However, the gain of the translational component of compensatory eye movement during combined translational and angular motion was approximately unity, in contrast to the gain of the response to isolated linear motion, which was approximately a half. Pursuit performance was always poorer than target following during self-motion. The LVOR responses in the light were greater than the sum of the LVOR responses in the dark with pursuit eye movements. We conclude that, in response to transient motion, there is a synergistic enhancement of the translational VOR with concurrent canal

  15. The vertical vestibulo-ocular reflex, and its interaction with vision during active head motion: effects of aging.

    Science.gov (United States)

    Kim, J S; Sharpe, J A

    2001-01-01

    The effects of aging on the vertical vestibulo-ocular reflex (VOR), and its interactions with vision during active head motion had not been investigated. We measured smooth pursuit, combined eye-head tracking, the VOR, and its visual enhancement and cancellation during active head motion in pitch using a magnetic search coil technique in 21 younger (age or = 65) subjects. With the head immobile, subjects pursued a target moving sinusoidally with a frequency range of 0.125 to 2.0 Hz, and with peak target accelerations (PTAs) ranging from 12 to 789 degrees /s(2). Combined eye-head tracking, the VOR in darkness, and its visual enhancement during fixation of an earth-fixed target (VVOR) were measured during active sinusoidal head motion with a peak-to-peak amplitude of 20 degrees at frequencies of 0.25, 0.5, 1.0 and 2.0 Hz. The efficacy of VOR cancellation was determined from VOR gains during combined eye-head tracking. VOR and VVOR gains were symmetrical in both directions and did not change with aging, except for reduced gains of the downward VOR and VVOR at low frequency (0.25 Hz). However, in the elderly, smooth pursuit, and combined eye-head tracking gains and the efficacy of cancellation of the VOR were significantly lower than in younger subjects. In both the young and elderly groups, VOR gain in darkness did not vary with the frequency of active head motion while the gains of smooth pursuit, combined eye-head tracking, and VVOR declined with increasing target frequency. VOR and VVOR performance in the elderly implicates relative preservation of neural structures subserving vertical vestibular smooth eye motion in senescence.

  16. The effect of vestibulo-ocular reflex deficits and covert saccades on dynamic vision in opioid-induced vestibular dysfunction.

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    Ramaioli, Cecilia; Colagiorgio, Paolo; Sağlam, Murat; Heuser, Fabian; Schneider, Erich; Ramat, Stefano; Lehnen, Nadine

    2014-01-01

    Patients with bilateral vestibular dysfunction cannot fully compensate passive head rotations with eye movements, and experience disturbing oscillopsia. To compensate for the deficient vestibulo-ocular reflex (VOR), they have to rely on re-fixation saccades. Some can trigger "covert" saccades while the head still moves; others only initiate saccades afterwards. Due to their shorter latency, it has been hypothesized that covert saccades are particularly beneficial to improve dynamic visual acuity, reducing oscillopsia. Here, we investigate the combined effect of covert saccades and the VOR on clear vision, using the Head Impulse Testing Device-Functional Test (HITD-FT), which quantifies reading ability during passive high-acceleration head movements. To reversibly decrease VOR function, fourteen healthy men (median age 26 years, range 21-31) were continuously administrated the opioid remifentanil intravenously (0.15 µg/kg/min). VOR gain was assessed with the video head-impulse test, functional performance (i.e. reading) with the HITD-FT. Before opioid application, VOR and dynamic reading were intact (head-impulse gain: 0.87±0.08, mean±SD; HITD-FT rate of correct answers: 90±9%). Remifentanil induced impairment in dynamic reading (HITD-FT 26±15%) in 12/14 subjects, with transient bilateral vestibular dysfunction (head-impulse gain 0.63±0.19). HITD-FT score correlated with head-impulse gain (R = 0.63, p = 0.03) and with gain difference (before/with remifentanil, R = -0.64, p = 0.02). One subject had a non-pathological head-impulse gain (0.82±0.03) and a high HITD-FT score (92%). One subject triggered covert saccades in 60% of the head movements and could read during passive head movements (HITD-FT 93%) despite a pathological head-impulse gain (0.59±0.03) whereas none of the 12 subjects without covert saccades reached such high performance. In summary, early catch-up saccades may improve dynamic visual function. HITD-FT is an appropriate method

  17. The effect of vestibulo-ocular reflex deficits and covert saccades on dynamic vision in opioid-induced vestibular dysfunction.

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    Cecilia Ramaioli

    Full Text Available Patients with bilateral vestibular dysfunction cannot fully compensate passive head rotations with eye movements, and experience disturbing oscillopsia. To compensate for the deficient vestibulo-ocular reflex (VOR, they have to rely on re-fixation saccades. Some can trigger "covert" saccades while the head still moves; others only initiate saccades afterwards. Due to their shorter latency, it has been hypothesized that covert saccades are particularly beneficial to improve dynamic visual acuity, reducing oscillopsia. Here, we investigate the combined effect of covert saccades and the VOR on clear vision, using the Head Impulse Testing Device-Functional Test (HITD-FT, which quantifies reading ability during passive high-acceleration head movements. To reversibly decrease VOR function, fourteen healthy men (median age 26 years, range 21-31 were continuously administrated the opioid remifentanil intravenously (0.15 µg/kg/min. VOR gain was assessed with the video head-impulse test, functional performance (i.e. reading with the HITD-FT. Before opioid application, VOR and dynamic reading were intact (head-impulse gain: 0.87±0.08, mean±SD; HITD-FT rate of correct answers: 90±9%. Remifentanil induced impairment in dynamic reading (HITD-FT 26±15% in 12/14 subjects, with transient bilateral vestibular dysfunction (head-impulse gain 0.63±0.19. HITD-FT score correlated with head-impulse gain (R = 0.63, p = 0.03 and with gain difference (before/with remifentanil, R = -0.64, p = 0.02. One subject had a non-pathological head-impulse gain (0.82±0.03 and a high HITD-FT score (92%. One subject triggered covert saccades in 60% of the head movements and could read during passive head movements (HITD-FT 93% despite a pathological head-impulse gain (0.59±0.03 whereas none of the 12 subjects without covert saccades reached such high performance. In summary, early catch-up saccades may improve dynamic visual function. HITD-FT is an appropriate

  18. Cross-axis adaptation improves 3D vestibulo-ocular reflex alignment during chronic stimulation via a head-mounted multichannel vestibular prosthesis

    Science.gov (United States)

    Dai, Chenkai; Fridman, Gene Y.; Chiang, Bryce; Davidovics, Natan; Melvin, Thuy-Anh; Cullen, Kathleen E.; Della Santina, Charles C.

    2012-01-01

    By sensing three-dimensional (3D) head rotation and electrically stimulating the three ampullary branches of a vestibular nerve to encode head angular velocity, a multichannel vestibular prosthesis (MVP) can restore vestibular sensation to individuals disabled by loss of vestibular hair cell function. However, current spread to afferent fibers innervating non-targeted canals and otolith endorgans can distort the vestibular nerve activation pattern, causing misalignment between the perceived and actual axis of head rotation. We hypothesized that over time, central neural mechanisms can adapt to correct this misalignment. To test this, we rendered five chinchillas vestibular-deficient via bilateral gentamicin treatment and unilaterally implanted them with a head mounted MVP. Comparison of 3D angular vestibulo-ocular reflex (aVOR) responses during 2 Hz, 50°/s peak horizontal sinusoidal head rotations in darkness on the first, third and seventh days of continual MVP use revealed that eye responses about the intended axis remained stable (at about 70% of the normal gain) while misalignment improved significantly by the end of one week of prosthetic stimulation. A comparable time course of improvement was also observed for head rotations about the other two semicircular canal axes and at every stimulus frequency examined (0.2–5 Hz). In addition, the extent of disconjugacy between the two eyes progressively improved during the same time window. These results indicate that the central nervous system rapidly adapts to multichannel prosthetic vestibular stimulation to markedly improve 3D aVOR alignment within the first week after activation. Similar adaptive improvements are likely to occur in other species, including humans. PMID:21374081

  19. Impairment of Long-Term Plasticity of Cerebellar Purkinje Cells Eliminates the Effect of Anodal Direct Current Stimulation on Vestibulo-Ocular Reflex Habituation

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    Suman Das

    2017-08-01

    Full Text Available Anodal direct current stimulation (DCS of the cerebellum facilitates adaptation tasks, but the mechanism underlying this effect is poorly understood. We have evaluated whether the effects of DCS effects depend on plasticity of cerebellar Purkinje cells (PCs. Here, we have successfully developed a mouse model of cerebellar DCS, allowing us to present the first demonstration of cerebellar DCS driven behavioral changes in rodents. We have utilized a simple gain down vestibulo-ocular reflex (VOR adaptation paradigm, that stabilizes a visual image on the retina during brief head movements, as behavioral tool. Our results provide evidence that anodal stimulation has an acute post-stimulation effect on baseline gain reduction of VOR (VOR gain in sham, anodal and cathodal groups are 0.75 ± 0.12, 0.68 ± 0.1, and 0.78 ± 0.05, respectively. Moreover, this anodal induced decrease in VOR gain is directly dependent on the PP2B medicated synaptic long-term potentiation (LTP and intrinsic plasticity pathways of PCs.

  20. Video Head Impulse Tests with a Remote Camera System: Normative Values of Semicircular Canal Vestibulo-Ocular Reflex Gain in Infants and Children

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    Sylvette R. Wiener-Vacher

    2017-09-01

    Full Text Available The video head impulse test (VHIT is widely used to identify semicircular canal function impairments in adults. But classical VHIT testing systems attach goggles tightly to the head, which is not tolerated by infants. Remote video detection of head and eye movements resolves this issue and, here, we report VHIT protocols and normative values for children. Vestibulo-ocular reflex (VOR gain was measured for all canals of 303 healthy subjects, including 274 children (aged 2.6 months–15 years and 26 adults (aged 16–67. We used the Synapsys® (Marseilles, France VHIT Ulmer system whose remote camera measures head and eye movements. HITs were performed at high velocities. Testing typically lasts 5–10 min. In infants as young as 3 months old, VHIT yielded good inter-measure replicability. VOR gain increases rapidly until about the age of 6 years (with variation among canals, then progresses more slowly to reach adult values by the age of 16. Values are more variable among very young children and for the vertical canals, but showed no difference for right versus left head rotations. Normative values of VOR gain are presented to help detect vestibular impairment in patients. VHIT testing prior to cochlear implants could help prevent total vestibular loss and the resulting grave impairments of motor and cognitive development in patients with residual unilateral vestibular function.

  1. Invariance of vestibulo-ocular reflex gain to head impulses in pitch at different initial eye-in-orbit elevations: implications for Alexander's law.

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    Anastasopoulos, Dimitri; Anagnostou, Evangelos

    2012-10-01

    These findings are in line with previous data on the horizontal vestibulo-ocular reflex (VOR) from this laboratory and suggest that eye position signals do not modulate natural vestibular responses. Hence, the Alexander's law (AL) phenomenon cannot be interpreted simply as a consequence of vestibular or oculomotor nuclei activity modulation with desired gaze. AL states that the intensity of the spontaneous nystagmus of a patient with a unilateral vestibular lesion grows with increasing gaze in the direction of the fast phase. Some of the mechanisms proposed to account for the gaze effects assume a direct modification of the normal VOR by eye position signals. We tested the validity of these assumptions and investigated the effects of gaze direction on the normal vertical human VOR in the behaviorally relevant high frequency range. Head and eye movements were recorded with the search coil method during passive head impulses in pitch, while subjects were asked to hold gaze at various elevation angles in 8° steps within ± 16° from the straight ahead reference position. Upward and downward head rotations produced VOR gains of similar magnitude. Furthermore, the gain remained unaffected by eye-in-orbit position for both upward and downward head impulses.

  2. Adaptive modifications of post-saccadic smooth pursuit eye movements and their interaction with saccades and the vestibulo-ocular reflex in the primate.

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    Nagao, S; Kitazawa, H

    1998-10-01

    Adaptation of the horizontal smooth pursuit eye movement was examined using step-ramp moving target paradigms in chronically prepared Macaca fuscata. Monkeys were trained to pursue a small target which moved in the horizontal plane in a 3 degrees step-10 degrees/s ramp or a 0 degrees step-10 degrees/s ramp mode for 300-400 ms. When the target moved from central fixation point in a step-ramp mode, the monkeys usually responded with an initial pursuit eye movement (latency, 100-120 ms) which reached to a nearly constant velocity of 4 degrees/s in 50 100 ms, followed by a 1-3.5 degrees catch-up saccade (latency, 170-230 ms). The catch-up saccade was followed by a 7-8 degrees/s post-saccadic pursuit. The post-saccadic pursuit velocity was measured 40-90 ms after the end of the catch-up saccade. When the target velocity was doubled (20 degrees/s) for 100-200 ms immediately after the onset of the catch-up saccade, the post-saccadic pursuit velocity increased by 40%. When the target velocity was decreased by half (5 degrees/s) immediately after the onset of the catch-up saccade for 150 ms, the post-saccadic pursuit velocity decreased by 30%. These increases or decreases of post-saccadic pursuit were observable within just 50-150 trials. The adaptation of post-saccadic pursuit occurred independent of the position of the target. The amplitude and latency of the catch-up saccade also increased correspondingly when the post-saccadic pursuit velocity was adaptively increased. Adaptation of smooth pursuit did not affect the dynamics of reflex eye movements, including the horizontal vestibulo-ocular reflex (HVOR) gain and phase measured by 0.33 Hz-10 degrees (peak-to-peak) turntable oscillations in darkness. Conversely, adaptation of the HVOR gain induced by a 2 h sustained oscillation of the turntable and screen in reversed direction at 0.33 Hz-10 degrees affected little the velocity of post-saccadic pursuit or the amplitude of the catch-up saccade. These results suggest that

  3. Inaccurate Saccades and Enhanced Vestibulo-Ocular Reflex Suppression during Combined Eye-Head Movements in Patients with Chronic Neck Pain: Possible Implications for Cervical Vertigo.

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    Johnston, Janine L; Daye, Pierre M; Thomson, Glen T D

    2017-01-01

    The primate ocular motor system is designed to acquire peripheral targets of interest by coordinating visual, vestibular, and neck muscle activation signals. The vestibulo-ocular reflex (VOR) is greatly reduced at the onset of large eye-head (gaze) saccades and resumes before the end of the saccades to stabilize eye-in-orbit and ensure accurate target acquisition. Previous studies have relied on manipulating head movements in normal individuals to study VOR suppression and gaze kinematics. We sought to determine if reduced head-on-trunk movement alters VOR suppression and gaze accuracy similar to experiments involving normal subjects and if intentionally increasing head and neck movement affects these dynamics. We measured head and gaze movements using magnetic search coil oculography in eight patients with cervical soft tissue disorders and seven healthy subjects. All participants made horizontal head-free saccades to acquire a laser dot target that stepped pseudorandomly 30-65° to either side of orbital mid-position, first using typical head and eye movements and again after being instructed to increase head amplitudes as much as possible. Compared to healthy subjects, patients made smaller head movements that contributed only 6% to total gaze saccade amplitudes. Head movements were also slowed, prolonged, and delayed. VOR suppression was increased and prolonged. Gaze saccades were inaccurate and delayed with long durations and decreased peak velocities. In patients with chronic neck pain, the internal commands issued for combined eye-head movements have large enough amplitudes to create accurate gaze saccades; however, because of increased neck stiffness and viscosity, the head movements produced are smaller, slower, longer, and more delayed than they should be. VOR suppression is disproportionate to the size of the actual gaze saccades because sensory feedback signals from neck proprioceptors are non-veridical, likely due to prolonged coactivation of cervical

  4. Evolution of the vestibulo-ocular system

    Science.gov (United States)

    Fritzsch, B.

    1998-01-01

    The evolutionary and developmental changes in the eye muscle innervation, the inner ear, and the vestibulo-ocular reflex are examined. Three eye muscle patterns, based on the innervation by distinct ocular motoneurons populations, can be identified: a lamprey, an elasmobranch, and a bony fish/tetrapod pattern. Four distinct patterns of variation in the vestibular system are described: a hagfish pattern, a lamprey pattern, an elasmobranch pattern, and a bony fish/tetrapod pattern. Developmental data suggest an influence of the hindbrain on ear pattern formation, thus potentially allowing a concomitant change of eye muscle innervation and ear variation. The connections between the ear and the vestibular nuclei and between the vestibular nuclei and ocular motoneurons are reviewed, and the role of neurotrophins for pattern specification is discussed. Three patterns are recognized in central projections: a hagfish pattern, a lamprey pattern, and a pattern for jawed vertebrates. Second-order connections show both similarities and differences between distantly related species such as lampreys and mammals. For example, elasmobranchs lack an internuclear system, which is at best poorly developed in lampreys. It is suggested that the vestibulo-ocular system shows only a limited degree of variation because of the pronounced functional constraints imposed on it.

  5. Transmastoid galvanic stimulation does not affect the vergence-mediated gain increase of the human angular vestibulo-ocular reflex.

    Science.gov (United States)

    Migliaccio, Americo A; Della Santina, Charles C; Carey, John P

    2013-02-01

    Vergence is one of several viewing contexts that require an increase in the angular vestibular-ocular reflex (aVOR) response. A previous monkey study found that the vergence-mediated gain (eye/head velocity) increase of the aVOR was attenuated by 64 % when anodic currents, which preferentially lower the activity of irregularly firing vestibular afferents, were delivered to both labyrinths. We sought to determine whether there was similar evidence implicating a role for irregular afferents in the vergence-mediated gain increase of the human aVOR. Our study is based upon analysis of the aVOR evoked by head rotations, delivered passively while subjects viewed a near (15 cm) or far (124 cm) target and applying galvanic vestibular stimulation (GVS) via surface electrodes. We tested 12 subjects during 2-3 sessions each. Vestibular stimuli consisted of passive whole-body rotations (sinusoids from 0.05-3 Hz and 12-25°/s, and transients with peak ~15°, 50°/s, 500°/s(2)) and head-on-body impulses (peak ~30°, 150°/s, 3,000°/s(2)). GVS was on for 10 s every 20 s. All polarity combinations were tested, with emphasis on uni- and bi-lateral anodic inhibition. The average stimulus current was 5.9 ± 1.6 mA (range: 3-9.5 mA), vergence angle (during near viewing) was 22.6 ± 2.8° and slow-phase eye velocity caused by left anodic current stimulation with head stationary was -3.4 ± 1.1°/s, -0.2 ± 0.6°/s and 2.5 ± 1.4°/s (torsion, vertical, horizontal). No statistically significant GVS effects were observed, suggesting that surface electrode GVS has no effect on the vergence-mediated gain increase of the aVOR at the current levels (~6 mA) tolerated by most humans. We conclude that clinically practical transmastoid GVS does not effectively silence irregular afferents and hypothesize that currents >10 mA are needed to reproduce the monkey results.

  6. Systems analysis of the vestibulo-ocular system. [mathematical model of vestibularly driven head and eye movements

    Science.gov (United States)

    Schmid, R. M.

    1973-01-01

    The vestibulo-ocular system is examined from the standpoint of system theory. The evolution of a mathematical model of the vestibulo-ocular system in an attempt to match more and more experimental data is followed step by step. The final model explains many characteristics of the eye movement in vestibularly induced nystagmus. The analysis of the dynamic behavior of the model at the different stages of its development is illustrated in time domain, mainly in a qualitative way.

  7. The Effect of Peripheral Vestibular Recovery on Improvements in Vestibulo-ocular Reflexes and Balance Control After Acute Unilateral Peripheral Vestibular Loss.

    Science.gov (United States)

    Allum, John H J; Scheltinga, Alja; Honegger, Flurin

    2017-12-01

    Patients with an acute unilateral peripheral vestibular deficit (aUPVD), presumed to be caused by vestibular neuritis, show asymmetrical vestibular ocular reflexes (VORs) that improve over time. Questions arise regarding how much of the VOR improvement is due to peripheral recovery or central compensation, and whether differences in peripheral recovery influence balance control outcomes. Thirty patients were examined at aUPVD onset and 3, 6, and 13 weeks later with four different VOR tests: caloric tests; rotating (ROT) chair tests performed in yaw with angular accelerations of 5 and 20 degrees/s; and video head impulse tests (vHIT) in the yaw plane. ROT and vHIT responses and balance control of 11 patients who had a caloric canal paresis (CP) more than 90% at aUPVD onset and no CP recovery (no-CPR) at 13 weeks in caloric tests were compared with those of 19 patients with CP recovery (CPR) to less than 30%, on average. Balance control was measured with a gyroscope system (SwayStar) recording trunk sway during stance and gait tasks. ROT and vHIT asymmetries of no-CPR and CPR patients reduced over time. The reduction was less at 13 weeks (36.2% vs. 83.5% on average) for the no-CPR patients. The no-CPR group asymmetries at 13 weeks were greater than those of CPR patients who had normal asymmetries. The greater asymmetries were caused by weaker deficit side responses which remained deficient in no-CPR patients at 13 weeks. Contra-deficit side vHIT and ROT responses remained normal. For all balance tests, sway was slightly greater for no-CPR compared with CPR patients at aUPVD onset and 3 weeks later. At 13 weeks, only sway during walking eyes closed was greater for the no-CPR group. A combination of 5 degrees/s ROT and balance tests could predict at onset (90% accuracy) which patients would have no-CPR at 13 weeks. These results indicate that for ROT and vHIT tests, central compensation is observed in CPR and no-CPR patients. It acts primarily by increasing deficit

  8. Abnormal Vestibulo-Ocular Reflexes in Autism: A Potential Endophenotype

    Science.gov (United States)

    2014-08-01

    children with hearing-impairment, VOR abnormalities appear to be an important predictor of impairment in motor performance (De Kegel et al., 2012...430. De Kegel , A., Maes, L., Baetens, T., Dhooge, I., and Van Waelvelde, H. (2012). The Influence of a Vestibular Dysfunction on the Motor Development

  9. Traumatic brain injury and vestibulo-ocular function: current challenges and future prospects

    Directory of Open Access Journals (Sweden)

    Wallace B

    2016-09-01

    Full Text Available Bridgett Wallace,1–4 Jonathan Lifshitz4–8 1360 Balance and Hearing, Department of Physical Therapy, Austin, TX, 2Concussion Health, Department of Clinical Education, Austin, TX, 3Conquering Concussions, Scottsdale, AZ, 4Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, 5Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, 6The CACTIS Foundation, Scottsdale, 7Phoenix VA Healthcare System, Phoenix, AZ, 8Department of Psychology, Arizona State University, Tempe, AZ, USA Abstract: Normal function of the vestibulo-ocular reflex (VOR coordinates eye movement with head movement, in order to provide clear vision during motion and maintain balance. VOR is generated within the semicircular canals of the inner ear to elicit compensatory eye movements, which maintain stability of images on the fovea during brief, rapid head motion, otherwise known as gaze stability. Normal VOR function is necessary in carrying out activities of daily living (eg, walking and riding in a car and is of particular importance in higher demand activities (eg, sports-related activities. Disruption or damage in the VOR can result in symptoms such as movement-related dizziness, blurry vision, difficulty maintaining balance with head movements, and even nausea. Dizziness is one of the most common symptoms following traumatic brain injury (TBI and is considered a risk factor for a prolonged recovery. Assessment of the vestibular system is of particular importance following TBI, in conjunction with oculomotor control, due to the intrinsic neural circuitry that exists between the ocular and vestibular systems. The purpose of this article is to review the physiology of the VOR and the visual-vestibular symptoms associated with TBI and to discuss assessment and treatment guidelines for TBI. Current challenges and future prospects will also be addressed. Keywords: traumatic brain injury, concussion, vestibular, ocular

  10. Ontogenetic development of vestibular reflexes in amphibians

    Directory of Open Access Journals (Sweden)

    Hans Straka

    2016-11-01

    Full Text Available Vestibulo-ocular reflexes ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt vestibulo-ocular reflexes (VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1-8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets.

  11. Vestibulo-Ocular Responses to Vertical Translation using a Hand-Operated Chair as a Field Measure of Otolith Function

    Science.gov (United States)

    Wood, S. J.; Campbell, D. J.; Reschke, M. F.; Prather, L.; Clement, G.

    2016-01-01

    The translational Vestibulo-Ocular Reflex (tVOR) is an important otolith-mediated response to stabilize gaze during natural locomotion. One goal of this study was to develop a measure of the tVOR using a simple hand-operated chair that provided passive vertical motion. Binocular eye movements were recorded with a tight-fitting video mask in ten healthy subjects. Vertical motion was provided by a modified spring-powered chair (swopper.com) at approximately 2 Hz (+/- 2 cm displacement) to approximate the head motion during walking. Linear acceleration was measured with wireless inertial sensors (Xsens) mounted on the head and torso. Eye movements were recorded while subjects viewed near (0.5m) and far (approximately 4m) targets, and then imagined these targets in darkness. Subjects also provided perceptual estimates of target distances. Consistent with the kinematic properties shown in previous studies, the tVOR gain was greater with near targets, and greater with vision than in darkness. We conclude that this portable chair system can provide a field measure of otolith-ocular function at frequencies sufficient to elicit a robust tVOR.

  12. Contribution of the otholiths to the human torsional vestibulo-ocular reflex

    NARCIS (Netherlands)

    Groen, E.L.; Bos, J.E.; Graaf, J.E. de

    1999-01-01

    The dynamic contribution of the otoliths to the human ocular torsion response was examined during passive sinusoidal body roll about an earth-horizontal axis (varying otolith input) and about an earth-vertical axis (unvarying otolith input). At a fixed amplitude of 25°, the stimulus frequency was

  13. The Adaptive Effects Of Virtual Interfaces: Vestibulo-Ocular Reflex and Simulator Sickness.

    Science.gov (United States)

    1998-08-07

    adaptation achieved within the first 16 minutes only. A direction adaptation stimulus would be utilized per Khater , et al. (1990). This method of...the vestibular organs within each inner ear. video-oculography (VOG): a method of collecting eye movement data using video recording techniques. Often...Other methods for measuring the VOR also exist (Halmagyi, 1995; Sharpe & Barber, 1993; Shelhamer, Robinson, & Tan, 1992). Gain and phase are the

  14. An Investigation and Analysis of the Vestibulo-Ocular Reflex (VOR) in a Vibration Environment

    Science.gov (United States)

    2013-03-01

    especially in the days when things seemed bleak. I would also like to thank several people that were instrumental in this research being accomplished. First...the dark-pupil method the camera was fit with an IR filter. To achieve this purpose a visibly opaque #87 Kodak Wratten 2 Optical Filter was used. A...eye is properly aligned and illuminated with the camera  Connect EOG leads using generous amounts of gel  Secure wires so not to obstruct or

  15. Three-Dimensional Vestibulo-Ocular Reflex in Humans: a Matter of Balance

    NARCIS (Netherlands)

    J. Goumans (Janine)

    2010-01-01

    textabstractThe objective of this thesis was to quantify three-dimensional ocular stability in response to head movements in healthy human subjects and in patients with various types of peripheral vestibular disorders. Despite a large increase in our knowledge from animal and human studies about the

  16. Three-dimensional vestibular eye and head reflexes of the chameleon: characteristics of gain and phase and effects of eye position on orientation of ocular rotation axes during stimulation in yaw direction.

    Science.gov (United States)

    Haker, H; Misslisch, H; Ott, M; Frens, M A; Henn, V; Hess, K; Sándor, P S

    2003-07-01

    We investigated gaze-stabilizing reflexes in the chameleon using the three-dimensional search-coil technique. Animals were rotated sinusoidally around an earth-vertical axis under head-fixed and head-free conditions, in the dark and in the light. Gain, phase and the influence of eye position on vestibulo-ocular reflex rotation axes were studied. During head-restrained stimulation in the dark, vestibulo-ocular reflex gaze gains were low (0.1-0.3) and phase lead decreased with increasing frequencies (from 100 degrees at 0.04 Hz to < 30 degrees at 1 Hz). Gaze gains were larger during stimulation in the light (0.1-0.8) with a smaller phase lead (< 30 degrees) and were close to unity during the head-free conditions (around 0.6 in the dark, around 0.8 in the light) with small phase leads. These results confirm earlier findings that chameleons have a low vestibulo-ocular reflex gain during head-fixed conditions and stimulation in the dark and higher gains during head-free stimulation in the light. Vestibulo-ocular reflex eye rotation axes were roughly aligned with the head's rotation axis and did not systematically tilt when the animals were looking eccentrically, up- or downward (as predicted by Listing's Law). Therefore, vestibulo-ocular reflex responses in the chameleon follow a strategy, which optimally stabilizes the entire retinal images, a result previously found in non-human primates.

  17. The reliability and response stability of dynamic testing of the vestibulo-ocular reflex in patients with vestibular disease.

    Science.gov (United States)

    Mohammad, Maha T; Whitney, Susan L; Marchetti, Gregory F; Sparto, Patrick J; Ward, Bryan K; Furman, Joseph M

    2011-01-01

    The purpose of the study was to investigate the test-retest reliability and response stability of the Dynamic Visual Acuity (DVA) and Gaze Stabilization Test (GST) in patients with vestibular disorders. Twenty-nine patients with vestibular disease (16-78 years) participated. Subjects performed the GST and DVA in pitch and yaw planes, twice in one session and once after 7-10 days. The GST output is the maximum head velocity at which the patient was able to identify orientation of the letter E. The DVA output is the change in visual acuity when moving the head compared to static acuity. Subjects indicated their level of dizziness and visual blurring using a visual analog scale. Within- and between-sessions intraclass correlation coefficients ranged between 0-0.5 for the DVA and GST measures, with better correlations for within-session assessments. Response stability (standard error of measurement / mean) of the GST ranged between 21-32% and the DVA ranged between 25-69% with vertical DVA being most influenced by measurement error. Subjects' symptoms did not correlate with performance on either test. The current test protocol needs refinement to enhance reliability and stability in persons with vestibular disorders.

  18. Tonic and phasic contributions to the pathways mediating compensation and adaptation of the vestibulo-ocular reflex.

    Science.gov (United States)

    Minor, Lloyd B; Lasker, David M

    2009-01-01

    Processes of vestibular compensation mediate recovery of many aspects of vestibular dysfunction following unilateral vestibular injury. The VOR in response to high-frequency, high-acceleration head movements, however, retains an enduring asymmetry. Head movements that are inhibitory with respect to semicircular canals on the intact side lead to a diminished VOR whereas head movements that are excitatory for semicircular canals on the intact side lead to a VOR that returns close to normal. We review our work directed toward understanding the processes of VOR compensation to high-frequency, high-acceleration head movements and the related topic of adaptation to changes in the visual requirements for a compensatory VOR. Our work has shown that the processes of both compensation and adaptation to these stimuli can be described by a mathematical model with inputs from tonic and phasic components. We have further shown that the dynamics of regular afferents have close resemblance to the tonic pathway whereas the dynamics of irregular afferents match those of the phasic pathway.

  19. Tonic and Phasic Contributions to the Pathways Mediating Compensation and Adaptation of the Vestibulo-ocular Reflex

    OpenAIRE

    Minor, Lloyd B.; Lasker, David M.

    2009-01-01

    Processes of vestibular compensation mediate recovery of many aspects of vestibular dysfunction following unilateral vestibular injury. The VOR in response to high-frequency, high-acceleration head movements, however, retains an enduring asymmetry. Head movements that are inhibitory with respect to semicircular canals on the intact side lead to a diminished VOR whereas head movements that are excitatory for semicircular canals on the intact side lead to a VOR that returns close to normal. We ...

  20. Eye Position Feedback in a Model of the Vestibulo-Ocular Reflex for Spino-Cerebellar Ataxia 6

    National Research Council Canada - National Science Library

    Anderson, J

    2001-01-01

    ..., incoordination, ocular motor dysfunction, and dysarthria due to degeneration of cerebellar and brainstem neurons. Recent studies have established that there are more than 16 genetically distinct subtypes...

  1. A cerebellar learning model of vestibulo-ocular reflex adaptation in wild-type and mutant mice

    NARCIS (Netherlands)

    Clopath, Claudia; Badura, Aleksandra; De Zeeuw, Chris I; Brunel, Nicolas

    2014-01-01

    Mechanisms of cerebellar motor learning are still poorly understood. The standard Marr-Albus-Ito theory posits that learning involves plasticity at the parallel fiber to Purkinje cell synapses under control of the climbing fiber input, which provides an error signal as in classical supervised

  2. Disorders of gaze related to vertigo: physiological mechanisms of vestibuloocular and optokinetic reflex

    OpenAIRE

    Saborío Morales, Lachiner; Monge Rodríguez, Silvia Leticia; Ramírez Rojas, Ana Carolina; Tencio Araya, José Alfredo; Brenes García, Oscar

    2016-01-01

    Vestibulo-ocular and optokinetic reflex are evoked by changes in head position or movement of the visual field, the result is a nystagmus, defined by a slow phase and subsequently a rapid phase. The objective of this work is to explain the physiological mechanism involved in these reflexes. The pathways explaining the generation of these responses include a complex integration system of the motor vestibular system, ocular system, many nucleus in the brainstem, cerebellum, somatosensory cortex...

  3. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in The VOR

    Directory of Open Access Journals (Sweden)

    Mina eRanjbaran

    2016-03-01

    Full Text Available The vestibulo-ocular reflex (VOR is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which can be distorted in case of peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain.In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e. different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies.

  4. Readaptation of the vestibuloocular reflex to 1g-Condition in immature lower vertebrates ( Xenopus laevis) after micro- or hypergravity exposure

    Science.gov (United States)

    Sebastian, C.; Horn, E.; Eβeling, K.; Neubert, J.

    The effects of altered gravitational conditions (AGC) on the development of the static vestibulo-ocular reflex (VOR) and readaptation to 1g were investigated in the amphibian Xenopus laevis. Tadpoles were exposed to microgravity (μg) during the German Space Mission D-2 for 10 days, using the STATEX closed survival system, or to 3g for 9 days during earth-bound experiments. At the beginning of AGC, the tadpoles had not yet developed the static VOR. The main results were: (i) Tadpoles with ug- or 3g-experience had a lower gain of the static VOR than the 1g-controls during the 2nd and 5th post-AGC days, (ii) Readaptation to response levels of 1g-reared controls usually occurred during the following weeks, except in slowly developing tadpoles with 3g-experience. Readaptation was less pronounced if, during the acute VOR test, tadpoles were rolled from the inclined to the normal posture than in the opposite test situation. It is postulated that (i) gravity is necessarily involved in the development of the static VOR, but only during a period including the time before onset of the first behavioural response; and (ii) readaptation which is superimposed by the processes of VOR development depends on many factors including the velocity of development, the actual excitation level of the vestibular systems and the neuroplastic properties of its specific pathways.

  5. Self-motion perception: assessment by real-time computer-generated animations

    Science.gov (United States)

    Parker, D. E.; Phillips, J. O.

    2001-01-01

    We report a new procedure for assessing complex self-motion perception. In three experiments, subjects manipulated a 6 degree-of-freedom magnetic-field tracker which controlled the motion of a virtual avatar so that its motion corresponded to the subjects' perceived self-motion. The real-time animation created by this procedure was stored using a virtual video recorder for subsequent analysis. Combined real and illusory self-motion and vestibulo-ocular reflex eye movements were evoked by cross-coupled angular accelerations produced by roll and pitch head movements during passive yaw rotation in a chair. Contrary to previous reports, illusory self-motion did not correspond to expectations based on semicircular canal stimulation. Illusory pitch head-motion directions were as predicted for only 37% of trials; whereas, slow-phase eye movements were in the predicted direction for 98% of the trials. The real-time computer-generated animations procedure permits use of naive, untrained subjects who lack a vocabulary for reporting motion perception and is applicable to basic self-motion perception studies, evaluation of motion simulators, assessment of balance disorders and so on.

  6. Leveraging Researcher Reflexivity to Consider a Classroom Event over Time: Reflexive Discourse Analysis of "What Counts"

    Science.gov (United States)

    Anderson, Kate T.

    2017-01-01

    This article presents a reflexive and critical discourse analysis of classroom events that grew out of a cross-cultural partnership with a secondary school teacher in Singapore. I aim to illuminate how differences between researcher and teacher assumptions about what participation in classroom activities should look like came into high relief when…

  7. Model simulation studies to clarify the effect on saccadic eye movements of initial condition velocities set by the Vestibular Ocular Reflex (VOR)

    Science.gov (United States)

    Nam, M. H.; Winters, J. M.; Stark, L.

    1981-01-01

    Voluntary active head rotations produced vestibulo-ocular reflex eye movements (VOR) with the subject viewing a fixation target. When this target jumped, the size of the refixation saccades were a function of the ongoing initial velocity of the eye. Saccades made against the VOR were larger in magnitude. Simulation of a reciprocally innervated model eye movement provided results comparable to the experimental data. Most of the experimental effect appeared to be due to linear summation for saccades of 5 and 10 degree magnitude. For small saccades of 2.5 degrees, peripheral nonlinear interaction of state variables in the neuromuscular plant also played a role as proven by comparable behavior in the simulated model with known controller signals.

  8. Eye Movements Are Correctly Timed During Walking Despite Bilateral Vestibular Hypofunction.

    Science.gov (United States)

    Anson, Eric R; Kiemel, Tim; Carey, John P; Jeka, John J

    2017-08-01

    Individuals with bilateral vestibular hypofunction (BVH) often report symptoms of oscillopsia (the perception that the world is bouncing or unstable) during walking. Efference copy/proprioception contributes to locomotion gaze stability in animals, sometimes inhibiting the vestibulo-ocular reflex (VOR). Gaze stability requires both adequate eye velocity and appropriate timing of eye movements. It is unknown whether eye velocity (VOR gain), timing (phase), or both are impaired for individuals with BVH during walking. Identifying the specific mechanism of impaired gaze stability can better inform rehabilitation options. Gaze stability was measured for eight individuals with severe BVH and eight healthy age- and gender-matched controls while performing a gaze fixation task during treadmill walking. Frequency response functions (FRF) were calculated from pitch eye and head velocity. A one-way ANOVA was conducted to determine group differences for each frequency bin of the FRF. Pearson correlation coefficients were calculated to determine the relationship between the real and imaginary parts of the FRF and the Oscillopsia Visual Analog Scale (oVAS) scores. Individuals with BVH demonstrated significantly lower gains than healthy controls above 0.5 Hz, but their phase was ideally compensatory for frequencies below 3 Hz. Higher oVAS scores were correlated with lower gain. Individuals with BVH demonstrated ideal timing for vertical eye movements while walking despite slower than ideal eye velocity when compared to healthy controls. Rehabilitation interventions focusing on enhancing VOR gain during walking should be developed to take advantage of the intact timing reported here. Specifically, training VOR gain while walking may reduce oscillopsia severity and improve quality of life.

  9. Functional testing of the vestibular ocular reflex (VOR

    Directory of Open Access Journals (Sweden)

    Stefano eRamat

    2012-03-01

    Full Text Available The experimental assessment of the vestibulo-ocular-reflex (VOR gain provides an objective and quantitative measure of VOR performance which is nonetheless difficult to correlate with its efficiency in everyday living conditions. We developed the Head Impulse Testing Device (HITD based on an inertial sensing system allowing to investigate the functional performance of the VOR by testing its gaze stabilization ability in response to head impulses at different head angular accelerations. HITD results on a population of 39 vestibular patients were compared to those of 22 controls. Overall the sensitivity of the HITD was 92% against the results of the clinical head impulse test and 83% against the clinical diagnosis, while the specificity was 58% against the clinical head impulse test and 83% against the diagnosis. The HITD appears to be a very promising tool for detecting abnormal VOR performance while providing information on the functional performance of the rotational VOR. As compared to the usual testing devices the HITD tests higher frequencies and accelerations that characterize head movements in everyday life activities and provides a functional assessment that is more likely to be related to the subject’s self-feeling.

  10. Does wearing a functional knee brace affect hamstring reflex time in subjects with anterior cruciate ligament deficiency during muscle fatigue?

    Science.gov (United States)

    Lam, Rita Y; Ng, Gabriel Y; Chien, Eric P

    2002-07-01

    To evaluate the effects of wearing a functional knee brace and muscle fatigue on hamstring reflex time in subjects with anterior cruciate ligament (ACL) deficiency. Repeated-measures clinical trial. Outpatient physical therapy department. Sixteen subjects with ACL deficiency. Subjects tested with and without a functional knee brace before and after an exercise protocol designed to fatigue the knee muscles. Latency of hamstring reflex muscle activity after sudden perturbation of the knee. Wearing a knee brace shortened the hamstring reflex latency regardless of fatigue (F(1,15)=20.62, Pknee brace facilitated hamstring muscle reflex, but muscle fatigue lengthened the hamstring reflex latency. Subjects with ACL deficiency should not rely on the knee brace to facilitate hamstring reflex for joint protection during prolonged sporting activities when muscles are fatigued. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of physical Medicine and Rehabilitation

  11. Scaling of compensatory eye movements during translations: Virtual versus real depth

    NARCIS (Netherlands)

    J. Dits (Joyce); W.M. King; J. van der Steen (Hans)

    2013-01-01

    textabstractVestibulo-ocular reflexes are the fastest compensatory reflex systems. One of these is the translational vestibulo-ocular reflex (TVOR) which stabilizes the gaze at a given fixation point during whole body translations. For a proper response of the TVOR the eyes have to counter rotate in

  12. The differential effects of fatigue on reflex response timing and amplitude in males and females.

    Science.gov (United States)

    Moore, Brian D; Drouin, Joshua; Gansneder, Bruce M; Shultz, Sandra J

    2002-10-01

    We examined the effects of fatigue on patellar tendon reflex responses in males and females. A spring-loaded reflex hammer elicited a standardized tendon tap with the knee positioned in an isokinetic dynamometer and flexed to 85 degrees. We recorded vastus lateralis activity (SEMG) and knee extension force production at the distal tibia (force transducer). Reflex trials were performed before and after (immediate, 2, 4, and 6 min) an isokinetic fatigue protocol to 50% MVC (90 degrees /s). For each event, pre-motor time (PMT), electromechanical delay (EMD), and total motor time (TMT) were obtained, as well as EMG amplitude (EMG(amp)), time to peak EMG (EMG(tpk)), peak force amplitude (F(amp)), time to peak force (F(tpk)), EMG:force ratio (E:F), and rate of force production (F(rate)=N/ms). TMT increased significantly in females following fatigue, while males showed no change. The increased TMT was due to an increased EMD with fatigue, while PMT was unaffected. EMG(amp) and F(amp) were somewhat diminished in females yet significantly augmented in males following fatigue, likely accounting for the differential changes in EMD noted. Results suggest males and females may respond differently to isokinetic fatigue, with males having a greater capacity to compensate for contraction force failure when responding to mechanical perturbations.

  13. Electrophysiological aspects of the middle ear muscle reflex in the rat: latency, rise time and effect on sound transmission.

    Science.gov (United States)

    van den Berge, H; Kingma, H; Kluge, C; Marres, E H

    1990-10-01

    The latency, the rise time and the influence of the acoustic reflex on sound transmission were investigated in the adult rat during ketamin anesthesia. This was done by recordings of the cochlear microphonics (CM) and electromyographic (EMG) recordings of the reflex responses of the tensor tympani muscle. The acoustic reflex was elicited by contralateral acoustic stimuli of which the intensity and frequency was varied. Ipsilaterally, the effect on sound transmission was determined by estimating the change in amplitude of the CM's of ipsilateral administered subliminal stimuli. It was shown that both the tensor tympani muscle and the stapedius muscle contribute in the reflex. The latency as well as the rise time of the reflex determined by CM recordings showed to be short (minimal values: 12 and 7 ms respectively). The mean latency of the tensor tympani muscle reflex, measured by EMG, was about 7 ms. The attenuation of 0.25-8 kHz tone bursts upto 115 dB SPL is limited to a mean maximum of 15 dB SPL. The maximal attenuation was shown to occur at 1 kHz. Frequencies above 2 kHz appeared to be the best elicitor of the middle ear muscle reflex.

  14. Time Course of the Soleus M Response and H Reflex after Lidocaine Tibial Nerve Block in the Rat

    Directory of Open Access Journals (Sweden)

    Kévin Buffenoir

    2013-01-01

    Full Text Available Aims. In spastic subjects, lidocaine is often used to induce a block predictive of the result provided by subsequent surgery. Lidocaine has been demonstrated to inhibit the Hoffmann (H reflex to a greater extent than the direct motor (M response induced by electrical stimulation, but the timecourse of these responses has not been investigated. Methods. An animal (rat model of the effects of lidocaine on M and H responses was therefore developed to assess this time course. M and H responses were recorded in 18 adult rats before and after application of lidocaine to the sciatic nerve. Results. Two to five minutes after lidocaine injection, M responses were markedly reduced (mean reduction of 44% and H reflexes were completely abolished. Changes were observed more rapidly for the H reflex. The effects of lidocaine then persisted for 100 minutes. The effect of lidocaine was therefore more prolonged on the H reflex than on the M response. Conclusion. This study confirms that lidocaine blocks not only alpha motoneurons but also Ia afferent fibres responsible for the H reflex. The authors describe, for the first time, the detailed time course of the effect of lidocaine on direct or reflex activation of motoneurons in the rat.

  15. Effects of ingested doses of caffeine on neuromuscular reflex response time in man.

    Science.gov (United States)

    Jacobson, B H; Edwards, S W

    1990-06-01

    To determine the effect of two doses of caffeine on a caudal (monosynaptic) reflex in humans, 30 subjects were randomly assigned to one of three groups. The groups received one of the following doses of caffeine per kilogram body weight using a double blind, placebo controlled design: 6 mg/kg, 3 mg/kg or a placebo. All of the subjects were similarly caffeine naive and were instructed to fast eight hours, refrain from caffeine for 96 hours, and avoid strenuous exercise 48 hours prior to testing. At the pre-test and post-test all subjects were given three trials of the patellar ligament reflex. Following pre-testing, subjects ingested either the caffeine solutions or an inert solution. After a one hour absorption period, subjects were post-tested. Gain scores were analyzed using a one-way ANOVA among the three groups, and a Newman-Keuls multiple range test was used to compare the three groups. The analysis revealed a significant difference in the gain score of the 6 mg/kg group. The control group had a mean gain of 4.3 msec, the 3 mg/kg group had a mean gain of 11.5 msec, and the 6 mg/kg group had a mean gain of 23.8 msec. Although the 6 mg/kg group was significantly different than the other two groups, a visible but nonsignificant difference was found between the 6 mg and 3 mg groups and the 3 mg and 0 mg groups. It was concluded that a 6 mg/kg dose of caffeine significantly lengthens reflex time in college age students.

  16. The first demonstration that a subset of women with hyperemesis gravidarum has abnormalities in the vestibuloocular reflex pathway

    Science.gov (United States)

    Goodwin, Thomas Murphy; Nwankwo, Odinaka A.; Davis-O’Leary, Linda; O’Leary, Dennis; Romero, Roberto; Korst, Lisa M.

    2008-01-01

    Objective The vestibular system is a major pathway to nausea and vomiting, and the vestibulo-ocular reflex (VOR) is a central component; its function can be studied using the vestibular autorotation test (VAT). We hypothesize that women with hyperemesis gravidarum (HG) may have VOR abnormalities. Study Design Women with HG were compared to women without HG using the VAT. Horizontal and vertical VOR gains and phases were evaluated at three frequency ranges: low (2.0–3.5 Hz), medium (>3.5 – 5.0 Hz), and high (>5.0 – 6.0 Hz) during pregnancy and postpartum. Results Twenty women with HG and 48 unaffected women were evaluated in early pregnancy. Women with HG had higher horizontal gains at all three frequency ranges. Horizontal phase differences were also observed at medium frequencies. No VAT differences were noted postpartum. Conclusions Women experiencing HG had a higher mean VOR horizontal gain and lower horizontal phase when compared to unaffected women. PMID:18928993

  17. Decrease of Horizontal Canal Vestibulo-Oculomotor Reflex Gain in the Elderly with Dysequilibrium without Lifetime Vertigo.

    Science.gov (United States)

    Teggi, Roberto; Trimarchi, Matteo; Gatti, Omar; Fornasari, Francesco; Bussi, Mario

    2017-01-01

    Unsteadiness in the elderly is a frequent complaint and a strong predictor of falls and psychological distress. Although there is a general consensus that it is a multifactorial condition, recent studies have focused on the role of aging of the vestibular system as a possible cofactor. The aim of our work was to assess horizontal canal function in the elderly. We evaluated the gain of horizontal vestibulo-ocular reflex (VOR) with a video head impulse test on a sample of 58 subjects aged >70 years without lifetime episodes of vertigo and correlated the value with different clinical conditions (hypertension, diabetes, prior cardiovascular and vascular disorders of the central nervous system, and falls). The mean value of the gain was 0.86 ± 0.12, and people aged between 70 and 80 years presented higher values (0.90 ± 0.1) compared to those >80 years (0.81 ± 0.13; p = 0.025). Previous vascular disorders of the central nervous system were a predictor of decreased VOR gain (p = 0.0003). A nonparametric analysis demonstrated that sex, age, and VOR gain (p ˂ 0.0001) were predictive of falls. Our data support the hypothesis of a decrease of VOR gain in the elderly. The decrease of canal function may therefore play a role in the risk of falls in the elderly. © 2017 S. Karger AG, Basel.

  18. [Comparative physiology of short-interval conditioned reflexes to time in different species of animals].

    Science.gov (United States)

    Dmitriev, A S; Kosteĭko, N D; Kurmaeva, A O

    1983-01-01

    Conditioned reflexes (CR) to short time intervals (from 0.25 to 20 min) were studied in rabbits, white rats and pigeons by motor food-procuring method. Some significant distinctions between species were revealed. The mean duration of formation of CR to time in rabbits amounted to 74 pairings, in rats--to 121, in pigeons--to 217. The optimal time interval varied in rabbits from 2 to 10 min, in rats from 1 to 4 min and in pigeons in was from 1 to 1,5 min. The longest interval which allowed to form the trace CR to time was not in excess of 22 min in rabbits, 10 min in rats and 4-5 min in pigeons. The shortest interval was within 15-45 s. Unstable and incorrect CR to time was formed when the intervals were shorter or longer than the optimal one. The accuracy of CR to time was: in rabbits approximately equal to 0.93-0.95 in rats approximately equal to 0.85-0.94, in pigeons approximately equal to 0.78-0.85. The data obtained have satisfactory explanation in the light of I. P. Pavlov's hypothesis on physiological mechanism of CR to time.

  19. Time-course analysis of stretch reflexes in hemiparetic subjects using an on-line spasticity measurement system.

    Science.gov (United States)

    Ju, M S; Chen, J J; Lee, H M; Lin, T S; Lin, C C; Huang, Y Z

    2000-02-01

    Spasticity after a stroke is usually assessed in a score form by subjectively determining the resistance of a joint to an externally imposed passive movement. This work presents a spasticity measurement system for on-line quantifying the stretch reflex of paretic limbs. Four different constant stretch velocities in a ramp-and-hold mode are used to elicit the stretch reflex of the elbow joint in spastic subjects. The subjects are tested at supine position with the upper limb stretched towards the ground, in contrast with the horizontally stretched movement used in other studies. By subtracting the baseline torque, reflex torque measured at a selected low stretch velocity of 5 deg/sec, the influence of gravity torque and inertial in vertical stretching mode can be minimized. The averaged speed-dependent reflex torque (ASRT), defined as the measured torque deviated from the baseline torque, is used for quantifying the spastic hypertonia. Four subjects having incurred cerebrovascular accident (CVA) are recruited for time-course study in which the measurements are taken at 72 hours, one week, one month, three months, and six months after onset of stroke. During the development of spasticity, the changes of ASRT and velocity sensitivity of ASRT of the involved and the intact elbow joints are discussed.

  20. Associative stimulation of the supraorbital nerve fails to induce timing-specific plasticity in the human blink reflex

    DEFF Research Database (Denmark)

    Zeuner, Kirsten E; Knutzen, Arne; Al-Ali, Asmaa

    2010-01-01

    Associative high-frequency electrical stimulation (HFS) of the supraorbital nerve in five healthy individuals induced long-term potentiation (LTP)-like or depression (LTD)-like changes in the human blink reflex circuit according to the rules of spike timing-dependent plasticity (Mao and Evinger...... the orbicularis oculi muscles, HFS(LTP) induced excessive LTP-like associative plasticity relative to healthy controls, which was normalized after botulinum toxin (BTX) injections (Quartarone et al, 2006)....

  1. Timing of Reflexive Visuospatial Orienting in Young, Young-Old, and Old-Old Adults

    Science.gov (United States)

    Langley, Linda K.; Friesen, Chris Kelland; Saville, Alyson L.; Ciernia, Annie T.

    2012-01-01

    This study examined adult age differences in reflexive orienting to two types of uninformative spatial cues: central arrows and peripheral onsets. In two experiments using a Posner cuing task, young adults (ages 18 – 28 yrs), young-old adults (ages 60 – 74 yrs), and old-old adults (ages 75 – 92 yrs) responded to targets that were preceded 100–1,000 ms earlier by a central arrow or a peripheral abrupt onset. In Experiment 1, the cue remained present upon target onset. Facilitation effects at early cue-target stimulus onset asynchronies (SOAs) were prolonged in duration for the two older groups relative to the young adults. At later cue-target SOAs, inhibition of return (IOR) that was initiated by peripheral onset cues was observed in the performance of young adults but not in that of the two older groups. In Experiment 2, the cue was presented briefly and removed prior to target onset. The change in cue duration minimized age differences (particularly for young-old adults) in facilitation effects and led to IOR for all three age groups. The findings are consistent with the idea that attentional control settings change with age, with higher settings for older adults leading to delayed disengagement from spatial cues. PMID:21394555

  2. Shoulder reflexes

    DEFF Research Database (Denmark)

    Diederichsen, Louise; Krogsgaard, Michael; Voigt, Michael

    2002-01-01

    Dynamic shoulder stability is dependent on muscular coordination and sensory inputs. In the shoulder, mechanoreceptors are found in the coracoacromial ligament, the rotator cuff tendons, the musculotendinous junctions of the rotator cuff and in the capsule. The number of receptors in the capsule...... is small compared to the number in the other shoulder structures. Proprioceptive information from numerous receptors in muscles and tendons is mediated via fast conducting nervefibers and probably contribute more to kinaestethic sensation than information from capsule and ligaments. Therefore it seems...... likely that the joint receptors have a more distinct role for the kinaestethic sense than muscle receptors. In cats a direct reflex from the afferents innervating the shoulder to the muscles around the shoulder has been presented. The reflex had an extremely short latency (2.7-3.1 ms). In man, a very...

  3. Selective staining of gastric biopsies for H. pylori does not affect detection rates or turnaround time and improves cost compared to reflexive staining.

    Science.gov (United States)

    Decker, Lauren; Routh, Joshua Keith; Snider, Jessica Sara; Hanson, Joshua Anspach

    2017-01-01

    To evaluate how reflexive versus selective H. pylori stains affect detection rates, turnaround time (TAT), and cost savings in a real life practice environment following an institutional policy change. The aforementioned parameters were evaluated in all cases in the year preceding and the year following an institutional policy change from reflexive to selective staining. 1497 patients comprised the reflexive stain (RS) group of which 228 (15.2%) were H. pylori positive. 1629 patients comprised the selective stain (SS) group of which 237 (14.5%) were H. pylori positive. There was no significant difference in H. pylori detection rates between the RS and SS groups (OR=0.95, 95% CI=0.78-1.15, p=0.59). TATs were similarly equivalent with a mean of 52.4h for the RS cohort and 53.7h for the SS cohort (p=0.344), both of which included a resident preview day. We calculated an average laboratory cost savings of $11.68 per case, which saved our department over $15,000 (37%) in the year following the policy change. Our results support a policy of selective staining for H. pylori as opposed to reflexive staining and go on to show that laboratories that change their policy can expect to generate cost savings without compromising detection rates or TAT. Copyright © 2016 Elsevier GmbH. All rights reserved.

  4. Validity and limitation of manual rotational test to detect impaired visual-vestibular interaction due to cerebellar disorders.

    Science.gov (United States)

    Murai, Norihiko; Funabiki, Kazuo; Naito, Yasushi; Ito, Juichi; Fukuyama, Hidenao

    2005-03-01

    The aim of this study was to investigate validity and limitation of the novel infrared system to record and analyze horizontal visual-vestibular interaction using whole-body rotation rapidly and conveniently in the routine vestibular clinic. We examined 11 patients with cerebellar dysequilibrium and 25 patients with peripheral dysequilibrium for vestibulo-ocular reflex in darkness (DVOR), visually-enhanced vestibulo-ocular reflex (VEVOR), and fixation suppression of vestibulo-ocular reflex (FSVOR), and compared the results with those of examination for head-fixed smooth pursuit and fixation suppression during caloric stimulation. The manual rotation stimuli were 0.5-0.75 Hz in frequency and 60-90 degrees /s in maximal angular velocity. Gain of vestibulo-ocular reflex in darkness was not significantly correlated with maximal slow phase velocity (MSPV) of caloric-induced nystagmus at that stimulus condition either in patients with peripheral dysequilibrium or in those with cerebellar dysequilibrium. An index for fixation suppression of vestibulo-ocular reflex during rotation stimulus was significantly lower in patients with cerebellar dysequilibrium than in normal control subjects and those with peripheral dysequilibrium. On the other hand, there was no significant difference among the two disease groups and the normal control group in gain of visually-enhanced vestibulo-ocular reflex. In about a half of patients with cerebellar dysequilibrium, measured smooth pursuit gain was lower than estimated smooth pursuit gain calculated based on a simple superposition theory of vestibulo-ocular reflex and smooth pursuit. Testing fixation suppression using the present system is an unusually convenient tool for detection of cerebellar dysequilibrium.

  5. Reflexives and reflexive constructions in Afrikaans

    Directory of Open Access Journals (Sweden)

    Johan Oosthuizen

    2016-01-01

    Full Text Available This article provides a non-formalistic description of the various reflexive pronouns in Afrikaans. In addition to the traditional class of reflexive pronouns, it is shown that possessive pronouns can also be used reflexively. The facts about (obligatory reflexivity involving these two types of pronoun are illustrated with reference to several types of construction in which they can occur. It is moreover shown that, besides the subject, the reflexive can take as its antecedent an expression functioning as the direct object, indirect object or as a prepositional object. Attention is also given to a number of non-reflexive constructions, that is, constructions containing inherently non-reflexive verbs and prepositions which disallow a coreferential relationship between the pronoun and some other expression in the sentence.

  6. Reflexives in Veracruz Huastec.

    Science.gov (United States)

    Constable, Peter G.

    A study examines various Huastec clause types that are reflexive in some sense, including ordinary reflexives, which involve co-reference. Two mutually exclusive morphosyntactic devices are used in Huastec: reflexive pronouns and verbal morphology. In this way, Huastec is like various European languages. Clauses involving reflexive pronouns and…

  7. Time-varying auditory gain control in response to double-pulse stimuli in harbour porpoises is not mediated by a stapedial reflex

    Directory of Open Access Journals (Sweden)

    Asger Emil Munch Schrøder

    2017-04-01

    Full Text Available Echolocating animals reduce their output level and hearing sensitivity with decreasing echo delays, presumably to stabilize the perceived echo intensity during target approaches. In bats, this variation in hearing sensitivity is formed by a call-induced stapedial reflex that tapers off over time after the call. Here, we test the hypothesis that a similar mechanism exists in toothed whales by subjecting a trained harbour porpoise to a series of double sound pulses varying in delay and frequency, while measuring the magnitudes of the evoked auditory brainstem responses (ABRs. We find that the recovery of the ABR to the second pulse is frequency dependent, and that a stapedial reflex therefore cannot account for the reduced hearing sensitivity at short pulse delays. We propose that toothed whale auditory time-varying gain control during echolocation is not enabled by the middle ear as in bats, but rather by frequency-dependent mechanisms such as forward masking and perhaps higher-order control of efferent feedback to the outer hair cells.

  8. Adaptive gaze stabilization through cerebellar internal models in a humanoid robot

    DEFF Research Database (Denmark)

    Vannucci, Lorenzo; Tolu, Silvia; Falotico, Egidio

    2016-01-01

    Two main classes of reflexes relying on the vestibular system are involved in the stabilization of the human gaze: The vestibulocollic reflex (VCR), which stabilizes the head in space and the vestibulo-ocular reflex (VOR), which stabilizes the visual axis to minimize retinal image motion. The VOR...

  9. Eye-head stabilization mechanism for a humanoid robot tested on human inertial data

    DEFF Research Database (Denmark)

    Vannucci, Lorenzo; Falotico, Egidio; Tolu, Silvia

    2016-01-01

    Two main classes of reflexes relying on the vestibular system are involved in the stabilization of the human gaze: the vestibulocollic reflex (VCR), which stabilizes the head in space and the vestibulo-ocular reflex (VOR), which stabilizes the visual axis to minimize retinal image motion. Together...... torso disturbance acquired on human subject performing various locomotion tasks confirm the effectiveness of our approach....

  10. Embodied Self-Reflexivity

    Science.gov (United States)

    Pagis, Michal

    2009-01-01

    Drawing on G. H. Mead and Merleau-Ponty, this paper aims to extend our understanding of self-reflexivity beyond the notion of a discursive, abstract, and symbolic process. It offers a framework for embodied self-reflexivity, which anchors the self in the reflexive capacity of bodily sensations. The data consist of two years of ethnographic…

  11. Who is who? Interpretation of multiple occurrences of the Chinese reflexive: evidence from real-time sentence processing.

    Directory of Open Access Journals (Sweden)

    Lan Shuai

    Full Text Available Theoretical linguists claim that the notorious reflexive ziji 'self' in Mandarin Chinese, if occurring more than once in a single sentence, can take distinct antecedents. This study tackles possibly the most interesting puzzle in the linguistic literature, investigating how two occurrences of ziji in a single sentence are interpreted and whether or not there are mixed readings, i.e., these zijis are interpretively bound by distinct antecedents. Using 15 Chinese sentences each having two zijis, we conducted two sentence reading experiments based on a modified self-paced reading paradigm. The general interpretation patterns observed showed that the majority of participants associated both zijis with the same local antecedent, which was consistent with Principle A of the Standard Binding Theory and previous experimental findings involving a single ziji. In addition, mixed readings also occurred, but did not pattern as claimed in the theoretical linguistic literature (i.e., one ziji is bound by a long-distance antecedent and the other by a local antecedent. Based on these results, we argue that: (i mixed readings were due to manifold, interlocking and conflicting perspectives taken by the participants; and (ii cases of multiple occurrences of ziji taking distinct antecedents are illicit in Chinese syntax, since the speaker, when expressing a sentence, can select only one P(erspective-Center that referentially denotes the psychological perspective in which the sentence is situated.

  12. Vestibular Restoration and Adaptation in Vestibular Neuritis and Ramsay Hunt Syndrome With Vertigo.

    Science.gov (United States)

    Martin-Sanz, Eduardo; Rueda, Almudena; Esteban-Sanchez, Jonathan; Yanes, Joaquin; Rey-Martinez, Jorge; Sanz-Fernandez, Ricardo

    2017-08-01

    To evaluate vestibular restoration and the evolution of the compensatory saccades in acute severe inflammatory vestibular nerve paralysis, including vestibular neuritis and Ramsay Hunt syndrome with vertigo. Prospective. Tertiary referral center. Vestibular neuritis (n = 18) and Ramsay Hunt syndrome patients with vertigo (n = 13) were enrolled. After treatment with oral corticosteroids, patients were followed up for 6 months. Functional recovery of the facial nerve was scored according to the House-Brackman grading system. Caloric and video head impulse tests were performed in every patient at the time of enrolment. Subsequently, successive video head impulse test (vHIT) exploration was performed at the 1, 3, and 6-month follow-up. Eighteen patients with vestibular neuritis and 13 with Ramsay Hunt syndrome and associated vertigo were included. Vestibular function was significantly worse in patients with Ramsay Hunt syndrome than in those with vestibular neuritis. Similar compensatory saccades velocity and latency values were observed in both groups, in both the caloric and initial vHIT tests. Successive vHIT results showed a significantly higher vestibulo-ocular reflex gain recovery in vestibular neuritis patients than in Ramsay Hunt syndrome patients. A significantly faster reduction in the latency, velocity, and organization of the compensatory saccades was observed in neuritis than in Ramsay Hunt syndrome patients. In addition to the recovery of the vestibulo-ocular reflex, the reduction of latency, velocity and the organization of compensatory saccades play a role in vestibular compensation.

  13. Outside home. Notes on reflexivity

    Directory of Open Access Journals (Sweden)

    Mara Clemente

    2017-01-01

    The paper proffers the idea in which a “reflexive process” on subjectivity can involve and/or hopefully involve the entire experience of the researcher, going beyond the borders of a single research. In the process, unexpected elements of subjectivity can come into play; in other cases the meaning attributed to them can change in time or can have a role different from what had been expected. Some elements, objects of epistemological analyses, as imposed by a reflexive approach, can become objects of attention also on the phenomenological level.

  14. Evaluation of the return of reflexes (eye reflexes and nose pinch reactions) after electric stunning of slaughter hogs and comparison of electrode positions, variations of time between stunning and bleeding, and different frequencies of electric current

    OpenAIRE

    Briese, Andreas

    2010-01-01

    Electric stunning results in paroxysmal cerebral (epileptic) seizures with temporary loss of consciousness. Death is caused either by bleeding or cardiac arrest. During routine slaughter it is difficult to tell weather animals regain consciousness or sensation. In eighteen studies involving twelve slaughter houses, 1,741 hogs were tested for eye reflexes and nose pinch reaction. Various stunning methods were used including asynchronous cardiac arrest stunning, head only stunning, and d...

  15. On Reflection: Is Reflexivity Necessarily Beneficial in Intercultural Education?

    Science.gov (United States)

    Blasco, Maribel

    2012-01-01

    This article explores how the concept of reflexivity is used in intercultural education. Reflexivity is often presented as a key learning goal in acquiring intercultural competence (ICC). Yet, reflexivity can be defined in different ways, and take different forms across time and space, depending on the concepts of selfhood that prevail and how…

  16. Cerebellar Ataxia with Bilateral Vestibulopathy: Description of a Syndrome and Its Characteristic Clinical Sign

    Science.gov (United States)

    Migliaccio, Americo A.; Halmagyi, G. Michael; McGarvie, Leigh A.; Cremer, Phillip D.

    2004-01-01

    We report four patients with the syndrome of cerebellar ataxia with bilateral vestibulopathy (CABV) and, using search coil oculography, we validate its characteristic clinical sign, namely impairment of the visually enhanced vestibulo-ocular reflex (VVOR) or doll's head reflex. In our four patients, CABV began in the sixth decade of life; they are…

  17. Reflexive intensification in Spanish: Toward a complex reflexive?

    DEFF Research Database (Denmark)

    Pedersen, Johan

    2005-01-01

    Spanish, intensifier, intensification, reflexive pronouns, anaphor, reanalysis, grammaticalization, sí, mismo......Spanish, intensifier, intensification, reflexive pronouns, anaphor, reanalysis, grammaticalization, sí, mismo...

  18. Practicing reflexive regulation

    NARCIS (Netherlands)

    S.I. Rutz (Suzanne)

    2017-01-01

    textabstractReflexive regulation has been developed to provide inspectors with strategies to deal with uncertain situations in which rules and roles are unclear, and inspecting involves multiple actors and learning how to deal with the situation is crucial. Reflexive regulation offers an alternative

  19. Cruciate ligament reflexes

    DEFF Research Database (Denmark)

    Krogsgaard, Michael R; Dyhre-Poulsen, Poul; Fischer-Rasmussen, Torsten

    2002-01-01

    the anterior cruciate ligament (ACL) was pulled, and tension in the ligament caused activity of the gamma motor neurones of the muscles around the knee. Impulses from the sensory nerves in ACL were activated during motion of the knee, in particular overstretching and combined extension and rotation. In humans......The idea of muscular reflexes elicited from sensory nerves of the cruciate ligaments is more than 100 years old, but the existence of such reflexes has not been proven until the recent two decades. First in animal experiments, a muscular excitation could be elicited in the hamstrings when...... in humans makes it unlikely that it is a directly protective reflex. Instead it may be involved in the updating of motor programs. Further research may characterize the reflex in details and map its pathways. The existence of this reflex indicate that the cruciate ligaments have an afferent function, which...

  20. Reflexivity in qualitative research

    DEFF Research Database (Denmark)

    Evans, Adam Brian; Nistrup, Anne; Henderson, Hannah

    2018-01-01

    Kingdom. Reflexive practice in both studies was affected by researcher biographies and by study design. In Study 1, both researchers were reasonably detached from the study context, the theoretical framework was in place from the very beginning, and reflexive practice was embedded in the study design......There has been something of a “reflexive shift” in sociological research. Sociological researchers are increasingly encouraged to be “present” within their work, and to recognize their own role in structuring the entire research process. One way to achieve this is through engagement in reflexive...... practice, that is, to reflect on our own values, beliefs, and biographies. It can be difficult to know exactly how a researcher should engage in these practices, however. Here, we discuss our reflexive practice in two case studies, both which utilized the same figurational theoretical framework...

  1. Etnography and Reflexivity

    Directory of Open Access Journals (Sweden)

    Mario Cardano

    2014-01-01

    Full Text Available This essay deals with a relevant and controversial topic – objectivity in ethnographic research. More specifically, I would like to examine how reflexive procedures, more precisely “reflexive account”, can increase the robustness of results gained through an ethnographic research. The essay is organized in five parts. I will start by giving a preliminary definition of the two key concepts which are at the center of the analysis – objectivity and reflexivity. I will then give a brief description of the epistemological framework in which the proposed conceptions of objectivity and reflexivity are located. Thirdly, I move on to consider the epistemic status of ethnographic research, and will emphasize that ethnographies are not just “theory-laden”, as many writers have stated, but also “praxis” or “procedure laden”. In other words, I will stress that it is not only theories which are inevitably embedded in research, influencing how observations can be made; much the same can also be said of the concrete research practices which contribute to determine the experience of the ethnographer and its representation in a text. Fourthly, I will discuss why it is useful to employ reflexive practices, and then immediately afterwards will illustrate the ways in which reflexive descriptions can contribute to greater objectivity of ethnographic accounts. In conclusion, I will discuss a number of objections which have been raised against this use of reflexivity.

  2. On Reflexive Data Models

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, S.

    2000-08-20

    An information system is reflexive if it stores a description of its current structure in the body of stored information and is acting on the base of this information. A data model is reflexive, if its language is meta-closed and can be used to build such a system. The need for reflexive data models in new areas of information technology applications is argued. An attempt to express basic notions related to information systems is made in the case when the system supports and uses meta-closed representation of the data.

  3. Morbidity in reflex sympathetic dystrophy

    OpenAIRE

    Murray, C; Cohen, A.; Perkins, T.; Davidson, J; Sills, J

    2000-01-01

    Reflex sympathetic dystrophy (RSD), an unusual diagnosis in general paediatrics, is well recognised by paediatric rheumatologists. This study reports the presentation and the clinical course of 46 patients (35 female, age range 8-15.2) with RSD. The patients saw professionals from an average of 2.3 specialties (range 1-5). Twenty five (54%) had a history of trauma. Median time to diagnosis was 12 weeks (range 1-130). Many children had multiple investigations and treatments. Once d...

  4. Evidence for sustained cortical involvement in peripheral stretch reflex during the full long latency reflex period.

    Science.gov (United States)

    Perenboom, M J L; Van de Ruit, M; De Groot, J H; Schouten, A C; Meskers, C G M

    2015-01-01

    Adaptation of reflexes to environment and task at hand is a key mechanism in optimal motor control, possibly regulated by the cortex. In order to locate the corticospinal integration, i.e. spinal or supraspinal, and to study the critical temporal window of reflex adaptation, we combined transcranial magnetic stimulation (TMS) and upper extremity muscle stretch reflexes at high temporal precision. In twelve participants (age 49 ± 13 years, eight male), afferent signals were evoked by 40 ms ramp and subsequent hold stretches of the m. flexor carpi radialis (FCR). Motor conduction delays (TMS time of arrival at the muscle) and TMS-motor threshold were individually assessed. Subsequently TMS pulses at 96% of active motor threshold were applied with a resolution of 5-10 ms between 10 ms before and 120 ms after onset of series of FCR stretches. Controlled for the individually assessed motor conduction delay, subthreshold TMS was found to significantly augment EMG responses between 60 and 90 ms after stretch onset. This sensitive temporal window suggests a cortical integration consistent with a long latency reflex period rather than a spinal integration consistent with a short latency reflex period. The potential cortical role in reflex adaptation extends over the full long latency reflex period, suggesting adaptive mechanisms beyond reflex onset. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. The plantar reflex

    Science.gov (United States)

    Araújo, Rui; Firmino-Machado, João; Correia, Pedro; Leitão-Marques, Mariana; Carvalho, João; Silva, Marta; Nogueira, Ana; Nunes, Carla

    2015-01-01

    Summary The utility of the plantar reflex in modern neurology is controversial. We studied the Babinski, Chaddock, and Oppenheim reflexes in terms of intraobserver, interobserver, and intertest agreement; sensitivity; positive predictive value (PPV); and observer bias. Sixty-two patients and 1,984 reflexes were analyzed. Intraobserver and interobserver agreement were weak (median κ Babinski/Chaddock (0.30) (p Babinski, 55.3% for the Chaddock, and 30.0% for the Oppenheim. PPV was 70.3% for the Babinski, 66.5% for the Chaddock, and 61.3% for the Oppenheim. Our results show consistently low observer agreement for the plantar reflex. The Babinski and the Chaddock demonstrated comparable sensitivity and PPV. PMID:29443235

  6. The vestibulocollic reflex.

    Science.gov (United States)

    Wilson, V J; Boyle, R; Fukushima, K; Rose, P K; Shinoda, Y; Sugiuchi, Y; Uchino, Y

    1995-01-01

    Stabilization of the head is required not only for adequate motor performance, such as maintaining balance while standing or walking, but also for the adequate reception of sensory inputs such as visual and auditory information. The vestibular organs, which consist of three approximately orthogonal semicircular canals (anterior, horizontal, posterior) and two otolith organs (utriculus, sacculus), provide the most important input for the detection of head movement. Activation of afferents from these receptors evokes the vestibulocollic reflex (VCR), which stabilizes head position in space. In this review, which is the outgrowth of a session of the vestibular symposium held in Hawaii in April, 1994, we discuss the neural substrate of this reflex and some aspects of the central processing involved in its production. Some topics are not considered, in particular the important interaction between the VCR and the cervicocollic reflex evoked by activation of neck afferents (70,119), and attempts to model the reflex (69).

  7. Reversed corrective saccades during head impulse test in acute cerebellar dysfunction.

    Science.gov (United States)

    Choi, Jeong-Yoon; Kim, Ji-Soo; Jung, Jin-Man; Kwon, Do-Young; Park, Moon Ho; Kim, Chulhan; Choi, June

    2014-04-01

    Patients with cerebellar lesions may show horizontal (positive)- or downward (perverted)-corrective saccades during horizontal head impulse test (HIT). However, corrective saccades in the direction of head rotation (reversed corrective saccades) have not been reported during HIT. We present two patients who showed reversed corrective saccades during horizontal HIT as an initial sign of acute cerebellitis. In contrast to the corrective saccades mostly observed in peripheral vestibular paresis, this paradoxical response indicates abnormally increased vestibulo-ocular responses due to cerebellar disinhibition over the vestibulo-ocular reflex. This paradoxical response should be considered an additional bedside cerebellar sign.

  8. Dissociation of locomotor and cerebellar deficits in a murine Angelman syndrome model

    NARCIS (Netherlands)

    Bruinsma, Caroline F; Schonewille, Martijn; Gao, Zhenyu; Aronica, Eleonora M A; Judson, Matthew C; Philpot, Benjamin D; Hoebeek, Freek E; van Woerden, Geeske M; De Zeeuw, Chris I; Elgersma, Ype

    2015-01-01

    Angelman syndrome (AS) is a severe neurological disorder that is associated with prominent movement and balance impairments that are widely considered to be due to defects of cerebellar origin. Here, using the cerebellar-specific vestibulo-ocular reflex (VOR) paradigm, we determined that cerebellar

  9. Does spectacle use lead to vestibular suppression?

    Science.gov (United States)

    Thakar, A

    2016-11-01

    Laboratory experiments indicate that changes in retinal image size result in adaptive recalibration or suppression of the vestibulo-ocular reflex. Myopia correction with spectacles or contact lenses also leads to retinal image size changes, and may bring about similar vestibulo-ocular reflex alterations. A hypothesis-generating preliminary investigation was conducted. In this cross-sectional study, findings of electronystagmography including bithermal caloric testing were compared between 17 volunteer myopes using spectacles or contact lenses and 17 volunteer emmetropes (with no refractive error). Bilateral hypoactive caloric responses were demonstrated in 6 of 11 spectacle users, in 1 of 6 contact lens users and in 1 of 17 emmetropes. Hypoactive caloric responses were significantly more likely in spectacle users than in emmetropes (p spectacles have vestibulo-ocular reflex suppression, as demonstrated by the caloric test. This has implications for the interpretation of electronystagmography and videonystagmography results, and highlights spectacle use as a possible cause of vestibular impairment. Further corroboration of these findings is warranted, with more precise and direct vestibulo-ocular reflex tests such as rotational tests and the head impulse test.

  10. Corneomandibular reflex: Anatomical basis

    Directory of Open Access Journals (Sweden)

    Michele Pistacchi

    2015-01-01

    Full Text Available Corneomandibular reflex is a pathological phenomenon evident in cases of severe brainstem damage. It is considered to be a pathological exteroceptive reflex, associated with precentro bulbar tract lesions. The sign is useful in distinguishing central neurological injuries to metabolic disorders in acutely comatose patients, localizing lesions to the upper brainstem area, determining the depth of coma and its evolution, providing evidence of uncal or transtentorial herniation in acute cerebral hemisphere lesions, and it is a marker of supraspinal level impairment in amyotrophic lateral sclerosis and multiple sclerosis. This sign was evident in a patient with severe brain damage. We discuss the literature findings and its relevance in prognosis establishment.

  11. Too Busy for Reflexivity?

    DEFF Research Database (Denmark)

    Ratner, Helene

    addresses relevant epistemological matters of concern, it has nevertheless been absorbed by an “empirical impulse” to describe everyday lives and practices (Maurer 2005:6). This paper explores some of the difficulties and frustrations related to imagining and realizing the epistemological ideals...... of reflexivity. However, instead of revisiting these somewhat tired epistemological debates, it explores Danish managers’ of primary schools analogous difficulties with realizing a prevailing ideal of reflexivity. The paper draws on ethnography in two Danish schools. The idea that the world is constructed...

  12. Assessment of Hyperactive Reflexes in Patients with Spinal Cord Injury

    Directory of Open Access Journals (Sweden)

    Dali Xu

    2015-01-01

    Full Text Available Hyperactive reflexes are commonly observed in patients with spinal cord injury (SCI but there is a lack of convenient and quantitative characterizations. Patellar tendon reflexes were examined in nine SCI patients and ten healthy control subjects by tapping the tendon using a hand-held instrumented hammer at various knee flexion angles, and the tapping force, quadriceps EMG, and knee extension torque were measured to characterize patellar tendon reflexes quantitatively in terms of the tendon reflex gain (Gtr, contraction rate (Rc, and reflex loop time delay (td. It was found that there are significant increases in Gtr and Rc and decrease in td in patients with spinal cord injury as compared to the controls (P<0.05. This study presented a convenient and quantitative method to evaluate reflex excitability and muscle contraction dynamics. With proper simplifications, it can potentially be used for quantitative diagnosis and outcome evaluations of hyperreflexia in clinical settings.

  13. Reflexivity of Routines

    DEFF Research Database (Denmark)

    Yamauchi, Yutaka; Hiramoto, Takeshi

    2016-01-01

    This study reconsiders the meaning and implications of reflexivity for the theory of routines. Due to their mundane nature, routines tend to be considered unambiguous phenomena that everyone can readily understand. The performative theory of routines has challenged this view by suggesting there i...

  14. Reflexive sig is an argument

    Directory of Open Access Journals (Sweden)

    Jóhannes Gísli Jónsson

    2011-10-01

    Full Text Available This paper argues that the simple reflexive pronoun sig is unambiguously a thematic argument in Icelandic. This is shown to be true not only of sig with naturally reflexive verbs but also of inherently reflexive sig. This view is mainly supported by two sets of facts: (i that sig is impossible with verbs that fail to theta-mark their object (middles and anticausatives, and (ii that case assignment works the same way for sig as for non- reflexive DP arguments. Potential counterarguments against my view involving focalization and reflexive passives are argued not to be valid.

  15. Reflex epilepsy: a review

    Directory of Open Access Journals (Sweden)

    Karim Nikkhah

    2017-01-01

    Full Text Available Interesting phenomena of reflex epileptic syndromes are characterized by epileptic seizures each one induced by specific stimulus with a variety of types. Simple triggers, which lead to seizures within seconds, are of sensory type (most commonly visual, most rarely tactile or proprioceptive stimuli. Complex triggers, which are mostly of cognitive type such as praxis, reading, talking, and music, usually induce the epileptic event within minutes. It should differ from what most epileptic patients report as provocative precipitants for seizures (such as emotional stress, fatigue, fever, sleep deprivation, alcohol, and menstrual cycle. The identification of a specific trigger is not only important for patients or their parents to avoid seizures, but also it might help neurologists to choose the most effective antiepileptic drug for each case. In addition, research in this area may possibly reveal some underlying pathophysiology of epileptic phenomena in the brain.In this review, we briefly introduce reported reflex epileptic seizures, their clinical features and management.

  16. Does spasticity result from hyperactive stretch reflexes? Preliminary findings from a stretch reflex characterization study.

    Science.gov (United States)

    Salazar-Torres, J De J; Pandyan, A D; Price, C I M; Davidson, R I; Barnes, M P; Johnson, G R

    2004-06-17

    To characterize the stretch reflex response of the biceps brachii in stroke patients with elbow spasticity (prior to or within 15 min of treatment with botulinum toxin) and non-impaired volunteers with the aim of quantifying the stretch reflex excitability and observe the differences between the groups. A cross-sectional study. Stretch reflexes from the biceps brachii were elicited following a controlled elbow extension. The amplitude, latency, rise time and duration, calculated from surface EMG recordings from the biceps brachii, were used to characterize the stretch reflex response. Seventeen non-impaired and 14 stroke patients participated. The amplitude was significantly lower in stroke patients than in non-impaired volunteers (p0.10). Reduction in the amplitude in stroke patients was unexpected suggesting the stretch reflex is not necessarily hyper-excitable in people with clinically diagnosed spasticity. Latency differences suggest decreased presynaptic inhibition and/or increased motor neurone excitability can occur following a stroke. However, carry over effects from previous botulinum toxin treatment may have confounded amplitude measurements. Further work evaluating the excitability of the stretch reflex independent of Botulinum toxin and its contribution to resistance to passive stretching is being conducted.

  17. Corporeal reflexivity and autism.

    Science.gov (United States)

    Ochs, Elinor

    2015-06-01

    Ethnographic video recordings of high functioning children with autism or Aspergers Syndrome in everyday social encounters evidence their first person perspectives. High quality visual and audio data allow detailed analysis of children's bodies and talk as loci of reflexivity. Corporeal reflexivity involves displays of awareness of one's body as an experiencing subject and a physical object accessible to the gaze of others. Gaze, demeanor, actions, and sotto voce commentaries on unfolding situations indicate a range of moment-by-moment reflexive responses to social situations. Autism is associated with neurologically based motor problems (e.g. delayed action-goal coordination, clumsiness) and highly repetitive movements to self-soothe. These behaviors can provoke derision among classmates at school. Focusing on a 9-year-old girl's encounters with peers on the playground, this study documents precisely how autistic children can become enmeshed as unwitting objects of stigma and how they reflect upon their social rejection as it transpires. Children with autism spectrum disorders in laboratory settings manifest diminished understandings of social emotions such as embarrassment, as part of a more general impairment in social perspective-taking. Video ethnography, however, takes us further, into discovering autistic children's subjective sense of vulnerability to the gaze of classmates.

  18. Wh-filler-gap dependency formation guides reflexive antecedent search.

    Science.gov (United States)

    Frazier, Michael; Ackerman, Lauren; Baumann, Peter; Potter, David; Yoshida, Masaya

    2015-01-01

    Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD) and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1), where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. (1). Which cowgirl did Mary expect to have injured herself due to negligence? Four eye-tracking text-reading experiments were conducted on examples like (1), differing in whether the embedded clause was non-finite (1 and 3) or finite (2 and 4), and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2) or the wh-dependency was associated with a position earlier in the sentence (3 and 4). The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Experiments 3 and 4), wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure.

  19. Wh-filler-gap dependency formation guides reflexive antecedent search

    Directory of Open Access Journals (Sweden)

    Michael eFrazier

    2015-10-01

    Full Text Available Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1, where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. 1. Which cowgirl did Mary expect to have injured herself due to negligence?Four eye-tracking text-reading experiments were conducted on examples like (1, differing in whether the embedded clause was non-finite (1 and 3 or finite (2 and 4, and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2 or the wh-dependency was associated with a position earlier in the sentence (3 and 4.The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Exp. 3 and 4, wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure.

  20. The cerebellum: a neuronal learning machine?

    Science.gov (United States)

    Raymond, J. L.; Lisberger, S. G.; Mauk, M. D.

    1996-01-01

    Comparison of two seemingly quite different behaviors yields a surprisingly consistent picture of the role of the cerebellum in motor learning. Behavioral and physiological data about classical conditioning of the eyelid response and motor learning in the vestibulo-ocular reflex suggests that (i) plasticity is distributed between the cerebellar cortex and the deep cerebellar nuclei; (ii) the cerebellar cortex plays a special role in learning the timing of movement; and (iii) the cerebellar cortex guides learning in the deep nuclei, which may allow learning to be transferred from the cortex to the deep nuclei. Because many of the similarities in the data from the two systems typify general features of cerebellar organization, the cerebellar mechanisms of learning in these two systems may represent principles that apply to many motor systems.

  1. Educating the Reflexive Practitioner

    Directory of Open Access Journals (Sweden)

    Marc J. Neveu

    2012-09-01

    Full Text Available “I cannot teach anybody anything, I can only make them think.”SocratesIntroductionStudio as a model of education is distinct from many other professionaldisciplines and although it can be quite rewarding on many levels it mayalso be an extremely unconstructive endeavor.1 The amount of time spent in studio typically far outweighs that spent for other courses and often atthe expense of such other courses. The dedication that students bring tothe studio is remarkable, yet much of the time spent in studio is not alwaysproductive. Students often complain of not knowing what is expected ofthem and as a result much of the time is spent thinking about what they think the professor wants to see as opposed to working through theirprojects. In an alternate scenario, students are crushed by the workload, tasks, demands or expectations of their instructors. In either case, the work is almost invariably driven by the students’ own creativity and imagination; unlike law, medicine, business, or engineering for example, where the interpretation and inquiry into case studies and cadaversis much less based on the personal introspection than established traditions. This extremely personal nature of the architectural studio canmake reviews either a devastating or extremely empowering process. As seen from the perspective of the larger university community, the studio is simply not an efficient way of education. The faculty to student ratio, for example, is not in accordance with other undergraduate disciplines. But this ratio, as we all know can also be a real strength. The often hermeticnature of the studio offers latitude for students to develop theirwork in relatively safe surroundings. This environment, however, may also foster the cult of personality that develops around certain professorsthat harkens back to the very roots of education but can also lead to anentourage of disciples who have no incentive to inform the Emperor that he or she is no longer

  2. Morbidity in reflex sympathetic dystrophy.

    Science.gov (United States)

    Murray, C S; Cohen, A; Perkins, T; Davidson, J E; Sills, J A

    2000-03-01

    Reflex sympathetic dystrophy (RSD), an unusual diagnosis in general paediatrics, is well recognised by paediatric rheumatologists. This study reports the presentation and the clinical course of 46 patients (35 female, age range 8-15.2) with RSD. The patients saw professionals from an average of 2.3 specialties (range 1-5). Twenty five (54%) had a history of trauma. Median time to diagnosis was 12 weeks (range 1-130). Many children had multiple investigations and treatments. Once diagnosis was made, treatment followed with physiotherapy and analgesics. Median time to recovery was seven weeks (range 1-140), with 27.5% relapsing. Nine children required assessment by the child and adolescent psychiatry team. This disease, though rare, has significant morbidity and it is therefore important to raise clinicians' awareness of RSD in childhood. Children with the condition may then be recognised and referred for appropriate management earlier, and spared unnecessary investigations and treatments which may exacerbate the condition.

  3. Ultimate concerns in late modernity: Archer, Bourdieu and reflexivity.

    Science.gov (United States)

    Farrugia, David; Woodman, Dan

    2015-12-01

    Through a critique of Margaret Archer's theory of reflexivity, this paper explores the theoretical contribution of a Bourdieusian sociology of the subject for understanding social change. Archer's theory of reflexivity holds that conscious 'internal conversations' are the motor of society, central both to human subjectivity and to the 'reflexive imperative' of late modernity. This is established through critiques of Bourdieu, who is held to erase creativity and meaningful personal investments from subjectivity, and late modernity is depicted as a time when a 'situational logic of opportunity' renders embodied dispositions and the reproduction of symbolic advantages obsolete. Maintaining Archer's focus on 'ultimate concerns' in a context of social change, this paper argues that her theory of reflexivity is established through a narrow misreading and rejection of Bourdieu's work, which ultimately creates problems for her own approach. Archer's rejection of any pre-reflexive dimensions to subjectivity and social action leaves her unable to sociologically explain the genesis of 'ultimate concerns', and creates an empirically dubious narrative of the consequences of social change. Through a focus on Archer's concept of 'fractured reflexivity', the paper explores the theoretical necessity of habitus and illusio for understanding the social changes that Archer is grappling with. In late modernity, reflexivity is valorized just as the conditions for its successful operation are increasingly foreclosed, creating 'fractured reflexivity' emblematic of the complex contemporary interaction between habitus, illusio, and accelerating social change. © London School of Economics and Political Science 2015.

  4. Reflexivity and social justice

    DEFF Research Database (Denmark)

    Maksimovic, Tijana; Jakobsen, Helle Nordentoft

    2017-01-01

    in the complexity of causes of social injustice in their own environment – i.e. how these are perpetuated in the design and implementation of national and organisational policies and how they influence counselling relationships. A generic challenge in career guidance is, for instance, to help individuals follow......Career practitioners’ reflexive understanding of their professional role as change agents in career guidance and counselling practices has a major impact on how social justice can be achieved. This entitles an awareness of the way in which guidance and counselling practices are embedded...

  5. Buccopalpebral reflex in Parkinson disease and blink reflex study.

    Science.gov (United States)

    Unal, Yasemin; Kutlu, Gulnihal; Erdal, Abidin; Inan, Levent E

    2013-07-01

    To define a new primitive reflex named the buccopalpebral reflex (BPR), and to investigate this reflex clinically and neurophysiologically in patients with Parkinson disease. This prospectively designed study included 17 patients, 9 BPR positive patients, and 8 BPR negative patients in Ankara Research and Training Hospital, Ankara, Turkey, and was carried out between January and December 2008. All patients had Parkinson disease without any medication. Using the blink reflex technique, 3 branches of the trigeminal nerve were stimulated. Additionally, the Mini Mental State Examination (MMSE), the Unified Parkinson`s Disease Rating Scale (UPDRS), the Hoehn and Yahr Score (HYS), the blink frequency, and the duration of Parkinson disease was also matched between the 2 groups. In patients with positive BPR, 5 had tremor and the remaining 4 had bradykinesia as a dominant symptom, while all other patients with negative BPR had only tremor. When blink reflex findings were compared between the 2 groups, R2 and contralateral R2 latencies that were taken by supraorbital stimulus were significantly shorter in the BPR positive patients. There were no statistically significant differences in terms of MMSE, UPDRS, HYS, and frequency of blinking, and duration of illness between the 2 groups. This reflex may be an indicator of sensitivity or decrease of threshold level such as Myerson`s sign, in which there is no inhibition in glabella reflex. The blink reflex findings support this hypothesis.

  6. Demand functions and reflexivity

    Science.gov (United States)

    Polyrakis, Ioannis A.

    2008-02-01

    In the theory of ordered spaces and in microeconomic theory two important notions, the notion of the base for a cone which is defined by a continuous linear functional and the notion of the budget set are equivalent. In economic theory the maximization of the preference relation of a consumer on any budget set defines the demand correspondence which at any price vector indicates the preferred vectors of goods and this is one of the fundamental notions of this theory. Contrary to the finite-dimensional economies, in the infinite-dimensional ones, the existence of the demand correspondence is not ensured. In this article we show that in reflexive spaces (and in some other classes of Banach spaces), there are only two classes of closed cones, i.e. cones whose any budget set is bounded and cones whose any budget set is unbounded. Based on this dichotomy result, we prove that in the first category of these cones the demand correspondence exists and that it is upper hemicontinuous. We prove also a characterization of reflexive spaces based on the existence of the demand correspondences.

  7. Current and Future Management of Bilateral Loss of Vestibular Sensation – An update on the Johns Hopkins Multichannel Vestibular Prosthesis Project

    Science.gov (United States)

    Della Santina, Charles C.; Migliaccio, Americo A.; Hayden, Russell; Melvin, Thuy-Anh; Fridman, Gene Y.; Chiang, Bryce; Davidovics, Natan S.; Dai, Chenkai; Carey, John P.; Minor, Lloyd B.; Anderson, Iee-Ching; Park, HongJu; Lyford-Pike, Sofia; Tang, Shan

    2012-01-01

    Bilateral loss of vestibular sensation can disable individuals whose vestibular hair cells are injured by ototoxic medications, infection, Ménière’s disease or other insults to the labyrinth including surgical trauma during cochlear implantation. Without input to vestibulo-ocular and vestibulo-spinal reflexes that normally stabilize the eyes and body, affected patients suffer blurred vision during head movement, postural instability, and chronic disequilibrium. While individuals with some residual sensation often compensate for their loss through rehabilitation exercises, those who fail to do so are left with no adequate treatment options. An implantable neuroelectronic vestibular prosthesis that emulates the normal labyrinth by sensing head movement and modulating activity on appropriate branches of the vestibular nerve could significantly improve quality of life for these otherwise chronically dizzy patients. This brief review describes the impact and current management of bilateral loss of vestibular sensation, animal studies supporting the feasibility of prosthetic vestibular stimulation, and a vestibular prosthesis designed to restore sensation of head rotation in all directions. Similar to a cochlear implant in concept and size, the Johns Hopkins Multichannel Vestibular Prosthesis (MVP) includes miniature gyroscopes to sense head rotation, a microcontroller to process inputs and control stimulus timing, and current sources switched between pairs of electrodes implanted within the vestibular labyrinth. In rodents and rhesus monkeys rendered bilaterally vestibular-deficient via treatment with gentamicin and/or plugging of semicircular canals, the MVP partially restores the vestibulo-ocular reflex for head rotations about any axis of rotation in 3-dimensional space. Our efforts now focus on addressing issues prerequisite to human implantation, including refinement of electrode designs and surgical technique to enhance stimulus selectivity and preserve

  8. Time-dependent bidirectional effects of chronic caffeine on functional recovery of the dorsal light reflex after hemilabyrinthectomy in the goldfish Carassius auratus.

    Science.gov (United States)

    Goodson, N B; Brockhoff, B L; Huston, J P; Spieler, R E

    2015-04-30

    Caffeine works through a variety of complex mechanisms to exert an often bidirectional set of functional and structural neurological changes in vertebrates. We investigated the effects of chronic caffeine exposure on functional recovery of the dorsal light reflex (DLR) in hemilabyrinthectomized common goldfish, Carassius auratus. In this lesion model, the unilateral removal of the vestibular organs results in a temporary loss of gravitationally modulated postural control which is quantifiable via the DLR. We compared the functional recovery over 24 days of post-surgery goldfish continuously held in a caffeine solution of 2.5mg/L (n=10), 5.0mg/L (n=10), 10.0mg/L (n=11), or 0.0mg/L control (n=9). Comparison to a sham surgery group (n=11) indicated statistically significant changes in the DLR of all hemilabyrinthectomized fish on day 1. The control group recovered over the study period and approached, but did not reach sham surgery DLR. Although the caffeine-treated fishes appeared to initiate some postural recovery within the first 2 weeks, beginning on day 10, all caffeine groups diverged from the control group with a deterioration of postural control. All three caffeine groups were significantly deficient in comparison with the control on days 10-24. These results suggest that caffeine exposure can at first be benign, but that high dosage or prolonged exposure hinders functional recovery. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  9. The Doyle-Saleh blink reflex.

    Science.gov (United States)

    Doyle, P W; Beegun, I; Saleh, H A

    2017-04-01

    When performing septoplasty or septorhinoplasty, we have observed that patients blink on injection of local anaesthetic (lidocaine 1 per cent with adrenaline 1:80 000) into the nasal mucosa of the anterior septum or vestibular skin, despite appropriate general anaesthesia. This study sought to quantify this phenomenon by conducting a prospective audit of all patients undergoing septoplasty or septorhinoplasty. Patients were observed for a blink reflex at the time of local anaesthetic infiltration into the nasal vestibule. Also measured at this point were propofol target-controlled infusion levels, remifentanil rate, bispectral index, blood pressure, heart rate, pupil size and position, and patient movement. There were 15 blink reflexes in the 30 patients observed. The average bispectral index value was 32.75 (range, 22-50) in the blink group and 26.77 (range, 18-49) in the non-blink group. No patients moved on local anaesthetic injection. The blink reflex appears to occur in 50 per cent of patients, despite a deep level of anaesthesia. Without an understanding and appreciation of the blink reflex, this event may result in a request to deepen anaesthesia, but this is not necessary and surgery can proceed safely.

  10. Proprioceptive reflexes and neurological disorders

    NARCIS (Netherlands)

    Schouten, A.C.

    2004-01-01

    Proprioceptive reflexes play an important role during the control of movement and posture. Disturbed modulation of proprioceptive reflexes is often suggested as the cause for the motoric features present in neurological disorders. In this thesis methods are developed and evaluated to quantify

  11. AMPUTATION AND REFLEX SYMPATHETIC DYSTROPHY

    NARCIS (Netherlands)

    GEERTZEN, JHB; EISMA, WH

    Reflex sympathetic dystrophy is a chronic pain syndrome characterized by chronic burning pain, restricted range of motion, oedema and vasolability. Patients are difficult to treat and the prognosis is very often poor. This report emphasizes that an amputation in case of a reflex sympathetic

  12. [Reflex seizures, cinema and television].

    Science.gov (United States)

    Olivares-Romero, Jesús

    2015-12-16

    In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot.

  13. Acoustic reflex and general anaesthesia.

    Science.gov (United States)

    Farkas, Z

    1983-01-01

    Infant and small children are not always able to cooperate in impedance measurements. For this reason it was decided, -in special cases, -to perform acoustic reflex examination under general anaesthesia. The first report on stapedius reflex and general anaesthesia was published by Mink et al. in 1981. Under the effect of Tiobutabarbital, Propanidid and Diazepam there is no reflex response. Acoustic reflex can be elicited with Ketamin-hydrochlorid and Alphaxalone-alphadolone acetate narcosis. The reflex threshold remains unchanged and the amplitude of muscle contraction is somewhat increased. The method was used: 1. to assess the type and degree of hearing loss in children with cleft palate and/or lip prior to surgery. 2. to exclude neuromuscular disorders with indication of pharyngoplasties. 3. to quantify hearing level in children--mostly multiply handicapped--with retarded speech development. The results of Behavioral Observation and Impedance Audiometry are discussed and evaluated.

  14. Reflexive Aero Structures for Enhanced Survivability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) proposes to develop an advanced reflexive structure system to increase the survivability of aerostructures. This reflexive...

  15. The swallowing reflex and its significance as an airway defensive reflex

    Directory of Open Access Journals (Sweden)

    Takashi eNishino

    2013-01-01

    Full Text Available Swallowing function, in humans, is very complex. Swallowing plays, not only an important role in food digestion, but also a major role in preventing the entrance of food and/or other materials into the lower respiratory tract. To achieve this, precise coordination is necessary between breathing and swallowing since the pharynx serves as a common pathway for both respiration and digestion. The swallowing reflex consists of afferent pathways, central integration, and efferent pathways. Any defect or disorder along reflex arc can cause a potential delay or impairment in swallow function. The swallowing reflex can be modulated not only by pathological factors but also by physiological factors. Among these, timing of swallows in relation to the phase of respiration may be the most important factor that determines the occurrence of pulmonary aspiration, since phases of inspiration and the expiration-inspiration transition are the most vulnerable for pulmonary aspiration.

  16. From ear to uncertainty: Vestibular contributions to cognitive function.

    OpenAIRE

    Paul eSmith; Yiwen eZheng

    2013-01-01

    In addition to the deficits in the vestibulo-ocular and vestibulo-spinal reflexes that occur following vestibular dysfunction, there is substantial evidence that vestibular loss also causes cognitive disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and neocortex play in spatial orientation. In this review we summarize the evidence that vestibular loss causes cognitive disorders, espe...

  17. Age-Related Neurochemical Changes in the Vestibular Nuclei

    OpenAIRE

    Paul eSmith

    2016-01-01

    There is evidence that the normal aging process is associated with impaired vestibulo-ocular reflexes (VOR) and vestibulo-spinal reflexes, causing reduced visual acuity and postural instability. Nonetheless, the available evidence is not entirely consistent, especially with respect to the VOR. Some recent studies have reported that VOR gain can be intact even above 80 years of age. Similarly, although there is evidence for age-related hair cell loss and neuronal loss in Scarpa’s ganglion and ...

  18. Acoustic reflex patterns in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Canale, Andrea; Albera, Roberto; Lacilla, Michelangelo; Canosa, Antonio; Albera, Andrea; Sacco, Francesca; Chiò, Adriano; Calvo, Andrea

    2017-02-01

    The aim of the study is to investigate acoustic reflex testing in amyotrophic lateral sclerosis patients. Amplitude, latency, and rise time of stapedial reflex were recorded for 500 and 1000 Hz contralateral stimulus. Statistical analysis was performed by the Wilcoxon test and the level of significance was set at 5 %. Fifty-one amyotrophic lateral sclerosis patients and ten sex- and age-matched control subjects were studied. Patients were further divided in two groups: amyotrophic lateral sclerosis-bulbar (38 cases, with bulbar signs at evaluation) and amyotrophic lateral sclerosis-spinal (13 cases, without bulbar signs at evaluation). Stapedial reflex was present in all patients. There was a statistically significant difference in the mean amplitude, latency, and rise time between the amyotrophic lateral sclerosis patients as compared with the controls. Amplitude was lower in both the amyotrophic lateral sclerosis-bulbar and the amyotrophic lateral sclerosis-spinal patients than in the controls (p amyotrophic lateral sclerosis cases with bulbar signs and, moreover, suggesting a possible subclinical involvement of the stapedial motor neuron even in amyotrophic lateral sclerosis-spinal patients. Amplitude and rise time seem to be good sensitive parameters for investigating subclinical bulbar involvement.

  19. Management of Reflex Anoxic Seizures

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2013-10-01

    Full Text Available Investigators at the Roald Dahl EEG Unit, Alder Hey Children’s NHS Foundation, Liverpool, UK, review the definition, pathophysiology, clinical presentation, and management of reflex anoxic seizures (RAS in children.

  20. Soleus stretch reflex during cycling.

    Science.gov (United States)

    Grey, M J; Pierce, C W; Milner, T E; Sinkjaer, T

    2001-01-01

    The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions during the crank cycle, producing ankle dorsiflexion perturbations of similar trajectory. The stretch reflex was greatest during the power phase of the crank cycle and was decreased to the level of background EMG during recovery. Matched perturbations were induced under static conditions at the same crank angle and background soleus EMG as recorded during the power phase of active pedaling. The magnitude of the stretch reflex was not statistically different from that during the static condition throughout the power phase of the movement. The results of this study indicate that the stretch reflex is not depressed during active cycling as has been shown with the H-reflex. This lack of depression may reflect a decreased susceptibility of the stretch reflex to inhibition, possibly originating from presynaptic mechanisms.

  1. [The oculocardiac reflex in blepharoplasties].

    Science.gov (United States)

    Rippmann, V; Scholz, T; Hellmann, S; Amini, P; Spilker, G

    2008-08-01

    The oculocardiac reflex (OCR) is a well-known phenomenon in ophthalmic surgery, but is rarely described in aesthetic blepharoplasty surgery. It was first mentioned in 1908 by Ascher and Dagnini. Since then, ophthalmologists and anaesthesiologists have regarded the onset of the oculocardiac reflex as a significant intraoperative problem, which is undermined by several case reports that describe dysrhythmias which have haved caused morbidity and death. Per definition the OCR is caused by ocular manipulation and involves intraoperative bradycardia by a change of 20 beats/minute compared to the preoperative heart rate or any dysrhythmia during the manipulation via a trigeminal-vagal-mediated reflex arc. Having operated on a 48-year-old, healthy woman in our clinic, who underwent a cardiac arrest during the blepharoplasty procedure, followed by a successful resuscitation, we investigated the onset of the OCR in our blepharoplasty patients within the last 3 years. The onset of the OCR was noted in 22 of 110 (20 %) blepharoplasty patients, mainly affecting younger, low-weighted patients operated under local anaesthesia. Awareness and treatment of this potentially life-threatening oculocardiac reflex are necessary. In most cases the onset of the reflex may be avoided by a gentle operation technique and by refraining from severe traction to the muscle or fat pad. The best treatment of a profound bradycardia caused by the OCR is to release tension to the muscle or fat pad in order to permit the heart rate to return to normal. Intraoperative monitoring is of utmost importance.

  2. Role of glycine in nociceptive and non-nociceptive bladder reflexes and pudendal afferent inhibition of these reflexes in cats.

    Science.gov (United States)

    Rogers, Marc J; Shen, Bing; Reese, Jeremy N; Xiao, Zhiying; Wang, Jicheng; Lee, Andy; Roppolo, James R; de Groat, William C; Tai, Changfeng

    2016-09-01

    This study examined the role of glycinergic transmission in nociceptive and non-nociceptive bladder reflexes and in inhibition of these reflexes by pudendal nerve stimulation (PNS). Cystometrograms (CMGs) were performed in α-chloralose anesthetized cats by intravesical infusion of saline or 0.25% acetic acid (AA) to trigger, respectively, non-nociceptive or nociceptive bladder reflexes. PNS at 2 or 4 times threshold (T) intensity for inducing anal twitch was used to inhibit the bladder reflexes. Strychnine (a glycine receptor antagonist) was administered in cumulative doses (0.001-0.3 mg/kg, i.v.) at 60-120 min intervals. Strychnine at 0.001-0.3 mg/kg significantly (P nociceptive bladder reflex. This is attributable to inhibition by glycine of another inhibitory mechanism. Glycine also has a minor role in PNS inhibition of the nociceptive bladder reflex. Neurourol. Urodynam. 35:798-804, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  3. Factors Affecting the Occurrence of Spinal Reflexes in Brain Dead Cases.

    Science.gov (United States)

    Hosseini, Mahsa Sadat; Ghorbani, Fariba; Ghobadi, Omid; Najafizadeh, Katayoun

    2015-08-01

    Brain death is defined as the permanent absence of all cortical and brain stem reflexes. A wide range of spontaneous or reflex movements that are considered medullary reflexes are observed in heart beating cases that appear brain dead, which may create uncertainty about the diagnosis of brain death and cause delays in deceased-donor organ donation process. We determined the frequency and type of medullary reflexes and factors affecting their occurrence in brain dead cases. During 1 year, 122 cases who fulfilled the criteria for brain death were admitted to the special intensive care unit for organ procurement of Masih Daneshvari Hospital. Presence of spinal reflexes was evaluated by trained coordinators and was recorded in a form in addition to other information including demographic characteristics, cause of brain death, time from detection of brain death, history of craniotomy, vital signs, serum electrolyte levels, and parameters of arterial blood gas determination. Most cases (63%) included in this study were male, and mean age was 33 ± 15 y. There was > 1 spinal reflex observed in 40 cases (33%). The most frequent reflex was plantar response (17%) following by myoclonus (10%), triple flexion reflex (9%), pronator extension reflex (8%), and undulating toe reflex (7%). Mean systolic blood pressure was significantly higher in cases who exhibited medullary reflexes than other cases (126 ± 19 mm Hg vs 116 ± 17 mm Hg; P = .007). Spinal reflexes occur frequently in brain dead cases, especially when they become hemodynamically stable after treatment in the organ procurement unit. Observing these movements by caregivers and family members has a negative effect on obtaining family consent and organ donation. Increasing awareness about spinal reflexes is necessary to avoid suspicion about the brain death diagnosis and delays in organ donation.

  4. Post-activation depression of soleus stretch reflexes in healthy and spastic humans

    DEFF Research Database (Denmark)

    Grey, Michael James; Klinge, Klaus; Crone, Clarissa

    2007-01-01

    delivered at different intervals. The magnitude of the stretch reflex and ankle torque response was assessed as a function of the time between perturbations. Soleus stretch reflexes were evoked with constant velocity (175 degrees /s) and amplitude (6 degrees ) plantar flexion perturbations. Soleus H...... of the soleus stretch reflex and H-reflex decreased as the interval between the stimulus/perturbation was decreased. Similarly, the stretch-evoked torque decreased. In the spastic participants, the post-activation depression of both reflexes and the stretch-evoked torque was significantly smaller than...... in healthy participants. These findings demonstrate that post-activation depression is an important factor in the evaluation of stretch reflex excitability and muscle stiffness in spasticity, and they strengthen the hypothesis that reduced post-activation depression plays a role in the pathophysiology...

  5. Can Treadmill Perturbations Evoke Stretch Reflexes in the Calf Muscles?

    Directory of Open Access Journals (Sweden)

    Lizeth H Sloot

    Full Text Available Disinhibition of reflexes is a problem amongst spastic patients, for it limits a smooth and efficient execution of motor functions during gait. Treadmill belt accelerations may potentially be used to measure reflexes during walking, i.e. by dorsal flexing the ankle and stretching the calf muscles, while decelerations show the modulation of reflexes during a reduction of sensory feedback. The aim of the current study was to examine if belt accelerations and decelerations of different intensities applied during the stance phase of treadmill walking can evoke reflexes in the gastrocnemius, soleus and tibialis anterior in healthy subjects. Muscle electromyography and joint kinematics were measured in 10 subjects. To determine whether stretch reflexes occurred, we assessed modelled musculo-tendon length and stretch velocity, the amount of muscle activity, as well as the incidence of bursts or depressions in muscle activity with their time delays, and co-contraction between agonist and antagonist muscle. Although the effect on the ankle angle was small with 2.8±1.0°, the perturbations caused clear changes in muscle length and stretch velocity relative to unperturbed walking. Stretched muscles showed an increasing incidence of bursts in muscle activity, which occurred after a reasonable electrophysiological time delay (163-191 ms. Their amplitude was related to the muscle stretch velocity and not related to co-contraction of the antagonist muscle. These effects increased with perturbation intensity. Shortened muscles showed opposite effects, with a depression in muscle activity of the calf muscles. The perturbations only slightly affected the spatio-temporal parameters, indicating that normal walking was retained. Thus, our findings showed that treadmill perturbations can evoke reflexes in the calf muscles and tibialis anterior. This comprehensive study could form the basis for clinical implementation of treadmill perturbations to functionally

  6. SwarmSight: Real-time Tracking of Insect Antenna Movements and Proboscis Extension Reflex Using a Common Preparation and Conventional Hardware.

    Science.gov (United States)

    Birgiolas, Justas; Jernigan, Christopher M; Gerkin, Richard C; Smith, Brian H; Crook, Sharon M

    2017-12-25

    Many scientifically and agriculturally important insects use antennae to detect the presence of volatile chemical compounds and extend their proboscis during feeding. The ability to rapidly obtain high-resolution measurements of natural antenna and proboscis movements and assess how they change in response to chemical, developmental, and genetic manipulations can aid the understanding of insect behavior. By extending our previous work on assessing aggregate insect swarm or animal group movements from natural and laboratory videos using the video analysis software SwarmSight, we developed a novel, free, and open-source software module, SwarmSight Appendage Tracking (SwarmSight.org) for frame-by-frame tracking of insect antenna and proboscis positions from conventional web camera videos using conventional computers. The software processes frames about 120 times faster than humans, performs at better than human accuracy, and, using 30 frames per second (fps) videos, can capture antennal dynamics up to 15 Hz. The software was used to track the antennal response of honey bees to two odors and found significant mean antennal retractions away from the odor source about 1 s after odor presentation. We observed antenna position density heat map cluster formation and cluster and mean angle dependence on odor concentration.

  7. Audiogenic reflex seizures in cats

    Science.gov (United States)

    Lowrie, Mark; Bessant, Claire; Harvey, Robert J; Sparkes, Andrew; Garosi, Laurent

    2015-01-01

    Objectives This study aimed to characterise feline audiogenic reflex seizures (FARS). Methods An online questionnaire was developed to capture information from owners with cats suffering from FARS. This was collated with the medical records from the primary veterinarian. Ninety-six cats were included. Results Myoclonic seizures were one of the cardinal signs of this syndrome (90/96), frequently occurring prior to generalised tonic–clonic seizures (GTCSs) in this population. Other features include a late onset (median 15 years) and absence seizures (6/96), with most seizures triggered by high-frequency sounds amid occasional spontaneous seizures (up to 20%). Half the population (48/96) had hearing impairment or were deaf. One-third of cats (35/96) had concurrent diseases, most likely reflecting the age distribution. Birmans were strongly represented (30/96). Levetiracetam gave good seizure control. The course of the epilepsy was non-progressive in the majority (68/96), with an improvement over time in some (23/96). Only 33/96 and 11/90 owners, respectively, felt the GTCSs and myoclonic seizures affected their cat’s quality of life (QoL). Despite this, many owners (50/96) reported a slow decline in their cat’s health, becoming less responsive (43/50), not jumping (41/50), becoming uncoordinated or weak in the pelvic limbs (24/50) and exhibiting dramatic weight loss (39/50). These signs were exclusively reported in cats experiencing seizures for >2 years, with 42/50 owners stating these signs affected their cat’s QoL. Conclusions and relevance In gathering data on audiogenic seizures in cats, we have identified a new epilepsy syndrome named FARS with a geriatric onset. Further studies are warranted to investigate potential genetic predispositions to this condition. PMID:25916687

  8. Two ways to support reflexivity

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine; Knudsen, Hanne

    2013-01-01

    ’. This requires participants to conduct experiments in their own organization, to reflect on and analyse their experiences with concepts from the curriculum. While the new language and the experimental teaching format are difficult, the participants learn a reflexive practice that can enable them to life up...

  9. Soleus stretch reflex during cycling

    DEFF Research Database (Denmark)

    Grey, Michael James; Pierce, C. W.; Milner, T. E.

    2001-01-01

    The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions durin...

  10. The reflexive case study method

    DEFF Research Database (Denmark)

    Rittenhofer, Iris

    2015-01-01

    This paper extends the international business research on small to medium-sized enterprises (SME) at the nexus of globalization. Based on a conceptual synthesis across disciplines and theoretical perspectives, it offers management research a reflexive method for case study research of postnationa...

  11. A armadilha do trabalho: reflexões sobre tempo, dinheiro e previdência The trap of work: reflections on time, money and welfare

    Directory of Open Access Journals (Sweden)

    Daniel Viana Teixeira

    2011-12-01

    Full Text Available A crise financeira internacional reavivou o debate sobre o papel do Estado na economia e sobre a tensão entre o endividamento público e a crescente demanda por prestações sociais de saúde, previdência e assistência. Sendo o cuidado e a assistência essenciais para a manutenção da vida humana em sociedade, a simples restrição dessas prestações estatais - recomendação técnica recorrente para a solução do problema - não parece ser uma alternativa. Dados os incentivos e injunções sociais para que os indivíduos busquem trabalho remunerado e se afastem das necessidades do ambiente familiar, caberia um reequilíbrio entre os incentivos sociais a essas diferentes modalidades da atividade humana. Os sistemas públicos de previdência podem funcionar como instrumento para o oferecimento de condições materiais para que os indivíduos possam, eles mesmos, prover o cuidado e a assistência de que suas famílias e pessoas próximas necessitam, pela garantia, no momento certo, de tempo e estabilidade econômica.The international financial crisis has revived the debate about the role of government in the economy and on the tension between public debt and rising demand for social services of health, welfare and assistance. Being care and assistance essential for sustaining human life in society, the mere restriction of these state benefits - recurring technical recommendation for the solution of the problem - seems not to be an alternative. Given the incentives and social injunctions for individuals to seek paid work and not depart from the needs of the household environment, it should be a balance between social incentives to these different modes of human activity. The public welfare systems can function as an instrument for the delivery of material conditions so that individuals can, themselves, provide care and assistance that their families and people close need, ensuring, at the right moment, free time and economic stability.

  12. Against the unaccusative analysis of reflexives

    NARCIS (Netherlands)

    Reinhart, T.; Siloni, T.

    1999-01-01

    In this paper we argue that the unaccusative analysis of reflexive verbs must be discarded, as reflexives systematically fail syntactic tests of unaccusativity. They are unergative entries, whose subject is an external argument, unlike the subject of unaccusatives. We adopt the view that reflexives

  13. Robotplattform för utvärdering av adaptiv bildstabilisering av kamera

    OpenAIRE

    Landgren, Axel

    2010-01-01

    This thesis describes the development of a robotic platform for evaluation of gaze stabilization algorithms built for the Sensorimotor Systems Laboratory at the University of British Columbia. The primary focus of the work was to measure the performance of a biomimetic vestibulo-ocular reflex controller for gaze stabilization using cerebellar feedback. A flexible robotic system was designed and built in order to run reproducible test sequences at high speeds featuring three dimensional linear...

  14. Eye movement recordings to investigate a supranuclear component in CPEO: a cross sectional study

    OpenAIRE

    Ritchie, Ailsa E; Griffiths, Philip; Chinnery, Patrick F.; Davidson, Adrian W

    2010-01-01

    Abstract Background: It has been postulated that eye movement disorders in CPEO have a neurological as well as a myopathic component to them. Aim: To investigate whether there is a supranuclear component to eye movement disorders in CPEO using eye movement recordings. Methods: We measured saccade and smooth pursuit characteristics together with vestibulo-ocular reflex (VOR) gain and VOR suppression (VORS) gain in 18 patients with CPEO and 34 normals using Eyelink II video-o...

  15. Eye movement recordings to investigate a supranuclear component in chronic progressive external ophthalmoplegia: a cross-sectional study

    OpenAIRE

    Ritchie, A. E.; Griffiths, P G; Chinnery, P. F.; Davidson, A W

    2010-01-01

    Background It has been postulated that eye movement disorders in chronic progressive external ophthalmoplegia (CPEO) have a neurological as well as a myopathic component to them. Aim To investigate whether there is a supranuclear component to eye movement disorders in CPEO using eye movement recordings. Methods Saccade and smooth pursuit (SP) characteristics together with vestibulo-ocular reflex (VOR) gain and VOR suppression (VORS) gain in 18 patients with CPEO and 34 normal patients...

  16. Long-Term Plasticity in Reflex Excitability Induced by Five Weeks of Arm and Leg Cycling Training after Stroke

    Directory of Open Access Journals (Sweden)

    Taryn Klarner

    2016-11-01

    Full Text Available Neural connections remain partially viable after stroke, and access to these residual connections provides a substrate for training-induced plasticity. The objective of this project was to test if reflex excitability could be modified with arm and leg (A & L cycling training. Nineteen individuals with chronic stroke (more than six months postlesion performed 30 min of A & L cycling training three times a week for five weeks. Changes in reflex excitability were inferred from modulation of cutaneous and stretch reflexes. A multiple baseline (three pretests within-subject control design was used. Plasticity in reflex excitability was determined as an increase in the conditioning effect of arm cycling on soleus stretch reflex amplitude on the more affected side, by the index of modulation, and by the modulation ratio between sides for cutaneous reflexes. In general, A & L cycling training induces plasticity and modifies reflex excitability after stroke.

  17. Reflex anuria following acute cardiac event.

    Science.gov (United States)

    Jeevagan, Vijayabala; Navinan, Mitrakrishnan; Munasinghe, Arunie; Nazar, Abdul; Wijewardena, Anura; Constantine, Godwin

    2013-05-20

    Reflex anuria is an uncommon cause for acute renal failure, which occurs almost always after manipulation or irritation to kidneys, ureter, bladder or other pelvic organs. Here we describe a case of acute renal failure due to reflex anuria following acute cardiac event. This patient had background history of urolithiasis. In the absence of other pre renal, renal or post- renal causes for acute kidney injury, we believe reflex anuria is the causative entity for acute renal failure in our patient. Acute renal failure due to reflex anuria is related to a reflex mechanism involving arteriolar vasoconstriction and urethral spasm. Patients with reflex anuria can be successfully managed with medical or surgical interventions. Our case suggests that reflex anuria should be considered as one of the differential diagnosis of acute renal failure following acute cardiac event, especially in patients with background urological problem.

  18. Educating the Reflexive Practitioner

    OpenAIRE

    Marc J. Neveu

    2012-01-01

    “I cannot teach anybody anything, I can only make them think.”SocratesIntroductionStudio as a model of education is distinct from many other professionaldisciplines and although it can be quite rewarding on many levels it mayalso be an extremely unconstructive endeavor.1 The amount of time spent in studio typically far outweighs that spent for other courses and often atthe expense of such other courses. The dedication that students bring tothe studio is remarkable, yet much of the time spent ...

  19. Being reflexive in qualitative grounded theory: discussion and application of a model of reflexivity.

    Science.gov (United States)

    Engward, Hilary; Davis, Geraldine

    2015-07-01

    A discussion of the meaning of reflexivity in research with the presentation of examples of how a model of reflexivity was used in a grounded theory research project. Reflexivity requires the researcher to make transparent the decisions they make in the research process and is therefore important in developing quality in nursing research. The importance of being reflexive is highlighted in the literature in relation to nursing research, however, practical guidance as to how to go about doing research reflexively is not always clearly articulated. This is a discussion paper. The concept of reflexivity in research is explored using the Alvesson and Skoldberg model of reflexivity and practical examples of how a researcher developed reflexivity in a grounded theory project are presented. Nurse researchers are encouraged to explore and apply the concept of reflexivity in their research practices to develop transparency in the research process and to increase robustness in their research. The Alvesson and Skoldberg model is of value in applying reflexivity in qualitative nursing research, particularly in grounded theory research. Being reflexive requires the researcher to be completely open about decisions that are made in the research process. The Alvesson and Skolberg model of reflexivity is a useful model that can enhance reflexivity in the research process. It can be a useful practical tool to develop reflexivity in grounded theory research. © 2015 John Wiley & Sons Ltd.

  20. Integrating Reflexivity in Livelihoods Research

    DEFF Research Database (Denmark)

    Prowse, Martin

    2010-01-01

    Much poverty and development research is not explicit about its methodology or philosophical foundations. Based on the extended case method of Burawoy and the epistemological standpoint of critical realism, this paper discusses a methodological approach for reflexive inductive livelihoods research...... that overcomes the unproductive social science dualism of positivism and social constructivism. The approach is linked to a conceptual framework and a menu of research methods that can be sequenced and iterated in light of research questions....

  1. Reflexivity in Narratives on Practice

    DEFF Research Database (Denmark)

    Jakobsen, Helle Nordentoft; Olesen, Lektor Birgitte Ravn

    a dialogic conception of practice as they entail a conceptual reframing of key elements in practice. In addition, the narratives expose a situational and relational, rather than normative, focus which allows for reflections on emotional and bodily experiences. In conclusion, we argue that practice narratives...... have the potential to bring about productive learning in organizational contexts since they appear to stimulate participants’ relational engagement and reflexivity....

  2. Reflexive fatherhood in everyday life

    DEFF Research Database (Denmark)

    Westerling, Allan

    2015-01-01

    This article looks at fathering practices in Denmark, using the findings from a research project on everyday family life in Denmark. It takes a social psychological perspective and employs discursive psychology and theories about reflexive modernisation. It shows how fathers orient towards intimacy...... this analysis and discussion, the article offers a way to understand the complexities of fathering in everyday life from the perspective of fathers....

  3. Reflex syncope: Diagnosis and treatment

    Directory of Open Access Journals (Sweden)

    Richard Sutton

    2017-12-01

    Full Text Available For the diagnosis of reflex syncope, diligent history-building with the patient and a witness is required. In the Emergency Department (ED, the assessment of syncope is a challenge which may be addressed by an ED Observation Unit or by a referral to a Syncope Unit. Hospital admission is necessary for those with life-threatening cardiac conditions although risk stratification remains an unsolved problem. Other patients may be investigated with less urgency by carotid sinus massage (>40 years, tilt testing, and electrocardiogram loop recorder insertion resulting in a clear cause for syncope. Management includes, in general terms, patient education, avoidance of circumstances in which syncope is likely, increase in fluid and salt consumption, and physical counter-pressure maneuvers. In older patients, those that will benefit from cardiac pacing are now well defined. In all patients, the benefit of drug therapy is often disappointing and there remains no ideal drug. A role for catheter ablation may emerge for the highly symptomatic reflex syncope patient. Keywords: Cardiac pacing, Catheter ablation, Diagnosis, Drugs, Management, Reflex syncope

  4. Reflexive anaphor resolution in spoken language comprehension: Structural constraints and beyond

    Directory of Open Access Journals (Sweden)

    Kaili eClackson

    2014-08-01

    Full Text Available We report results from an eye-tracking during listening study examining English-speaking adults’ online processing of reflexive pronouns, and specifically whether the search for an antecedent is restricted to syntactically appropriate positions. Participants listened to a short story where the recipient of an object was introduced with a reflexive, and were asked to identify the object recipient as quickly as possible. This allowed for the recording of participants’ offline interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our offline results show that the ultimate interpretation for reflexives was constrained by binding principles, the response time and eye-movement data revealed that during processing participants were temporarily distracted by a structurally inappropriate competitor antecedent when this was prominent in the discourse. These results indicate that in addition to binding principles, online referential decisions are also affected by discourse-level information.

  5. An Intelligent Computerized Stretch Reflex Measurement System For Clinical And Investigative Neurology

    Science.gov (United States)

    Flanagan, P. M.; Chutkow, J. G.; Riggs, M. T.; Cristiano, V. D.

    1987-05-01

    We describe the design of a reliable, user-friendly preprototype system for quantifying the tendon stretch reflexes in humans and large mammals. A hand-held, instrumented reflex gun, the impactor of which contains a single force sensor, interfaces with a computer. The resulting test system can deliver sequences of reproducible stimuli at graded intensities and adjustable durations to a muscle's tendon ("tendon taps"), measure the impacting force of each tap, and record the subsequent reflex muscle contraction from the same tendon -- all automatically. The parameters of the reflex muscle contraction include latency; mechanical threshold; and peak time, peak magnitude, and settling time. The results of clinical tests presented in this paper illustrate the system's potential usefulness in detecting neurologic dysfunction affecting the tendon stretch reflexes, in documenting the course of neurologic illnesses and their response to therapy, and in clinical and laboratory neurologic research.

  6. Lock-and-key mechanisms of cerebellar memory recall based on rebound currents.

    Science.gov (United States)

    Wetmore, Daniel Z; Mukamel, Eran A; Schnitzer, Mark J

    2008-10-01

    A basic question for theories of learning and memory is whether neuronal plasticity suffices to guide proper memory recall. Alternatively, information processing that is additional to readout of stored memories might occur during recall. We formulate a "lock-and-key" hypothesis regarding cerebellum-dependent motor memory in which successful learning shapes neural activity to match a temporal filter that prevents expression of stored but inappropriate motor responses. Thus, neuronal plasticity by itself is necessary but not sufficient to modify motor behavior. We explored this idea through computational studies of two cerebellar behaviors and examined whether deep cerebellar and vestibular nuclei neurons can filter signals from Purkinje cells that would otherwise drive inappropriate motor responses. In eyeblink conditioning, reflex acquisition requires the conditioned stimulus (CS) to precede the unconditioned stimulus (US) by >100 ms. In our biophysical models of cerebellar nuclei neurons this requirement arises through the phenomenon of postinhibitory rebound depolarization and matches longstanding behavioral data on conditioned reflex timing and reliability. Although CS-US intervals100 ms. This bound reflects the minimum time for deinactivation of rebound currents such as T-type Ca2+. In vestibulo-ocular reflex adaptation, hyperpolarization-activated currents in vestibular nuclei neurons may underlie analogous dependence of adaptation magnitude on the timing of visual and vestibular stimuli. Thus, the proposed lock-and-key mechanisms link channel kinetics to recall performance and yield specific predictions of how perturbations to rebound depolarization affect motor expression.

  7. Somatoautonomic reflexes in acupuncture therapy: A review.

    Science.gov (United States)

    Uchida, Sae; Kagitani, Fusako; Sato-Suzuki, Ikuko

    2017-03-01

    Oriental therapies such as acupuncture, moxibustion, or Anma, have been used to treat visceral disorders since ancient times. In each of these therapies, stimulation of the skin or underlying muscles leads to excitation of afferent nerves. The sensory information is carried to the central nervous system, where it is transferred to autonomic efferents, thus affecting visceral functions. This neuronal pathway, known as the "somatoautonomic reflex", has been systematically studied by Sato and his colleagues for over a half century. Nearly all their studies were conducted in anesthetized animals, whereas human patients are conscious. Responses in patients or the events following therapeutic somatic stimulation may differ from those observed in anesthetized animals. In fact, it is increasingly apparent that the responses in patients and animals are not always coincident, and the differences have been difficult for clinicians to reconcile. We review the mechanism of the "somatoautonomic reflex" as described in anesthetized animals and then discuss how it can be applied clinically. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Reflex anuria following acute cardiac event

    OpenAIRE

    Jeevagan, Vijayabala; Navinan, Mitrakrishnan; Munasinghe, Arunie; Nazar, Abdul; Wijewardena, Anura; Constantine, Godwin

    2013-01-01

    Background Reflex anuria is an uncommon cause for acute renal failure, which occurs almost always after manipulation or irritation to kidneys, ureter, bladder or other pelvic organs. Case presentation Here we describe a case of acute renal failure due to reflex anuria following acute cardiac event. This patient had background history of urolithiasis. In the absence of other pre renal, renal or post- renal causes for acute kidney injury, we believe reflex anuria is the causative entity for acu...

  9. Hand muscle reflexes following air puff stimulation.

    Science.gov (United States)

    Deuschl, G; Feifel, E; Guschlbauer, B; Lücking, C H

    1995-01-01

    Hand muscle reflexes following muscle stretch and electrical nerve stimulation show a typical pattern consisting of short- and long-latency reflexes. The present investigation was designed to test reflexes following pure cutaneous stimulation. Air puffs were delivered to the palmar tip and the nail bed of the first, second and fifth fingers during isotonic contraction of hand muscles. The EMGs from the thenar muscles, the first dorsal interosseous muscle and the hypothenar muscles were recorded. Reflexes were obtained in all muscles, with a typical configuration consisting of a short-latency excitatory component (cutaneous long-latency reflex I, cLLR I) and a second excitatory component (cutaneous long-latency reflex II, cLLR II), with an inhibitory component between them. The size of cLLR II differed depending on the area stimulated and the muscle recorded. We found the largest responses always in the muscle acting on the stimulated finger. The reflex size depended on the strength of air puff stimulation. Allowing small displacements of the fingers led to an additional increase in the size of the reflex. The pattern of reflexes was identical independent of whether the finger tip or the nail bed was stimulated, but the size of the reflexes was smaller following nail bed stimulation. Following blockade of the cutaneous nerve branches of the thumb with local anaesthetics, air puff stimulation of the thumb no longer elicited this reflex pattern. Hence, under our experimental conditions, cutaneous receptors were the only source of afferent input for these reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Intrapartum Synthetic Oxytocin Reduce the Expression of Primitive Reflexes Associated with Breastfeeding

    Science.gov (United States)

    Olza Fernández, Ibone; Malalana Martínez, Ana M.; González Armengod, Carmen; Costarelli, Valeria; Millán Santos, Isabel; Fernández-Cañadas Morillo, Aurora; Pérez Riveiro, Pilar; López Sánchez, Francisco; García Murillo, Lourdes

    2015-01-01

    Abstract Aim: Several synthetic peptide manipulations during the time surrounding birth can alter the specific neurohormonal status in the newborn brain. This study is aimed at assessing whether intrapartum oxytocin administration has any effect on primitive neonatal reflexes and determining whether such an effect is dose-dependent. Materials and Methods: A cohort prospective study was conducted at a tertiary hospital. Mother–infant dyads who received intrapartum oxytocin (n=53) were compared with mother–infant dyads who did not receive intrapartum oxytocin (n=45). Primitive neonatal reflexes (endogenous, antigravity, motor, and rhythmic reflexes) were quantified by analyzing videotaped breastfeeding sessions in a biological nurturing position. Two observers blind to the group assignment and the oxytocin dose analyzed the videotapes and assesed the newborn's state of consciousness according to the Brazelton scale. Results: The release of all rhythmic reflexes (p=0.01), the antigravity reflex (p=0.04), and total primitive neonatal reflexes (p=0.02) in the group exposed to oxytocin was lower than in the group not exposed to oxytocin. No correlations were observed between the dose of oxytocin administered and the percentage of primitive neonatal reflexes released (r=0.03; p=0.82). Conclusions: Intrapartum oxytocin administration might inhibit the expression of several primitive neonatal reflexes associated with breastfeeding. This correlation does not seem to be dose-dependent. PMID:25785487

  11. Intrapartum synthetic oxytocin reduce the expression of primitive reflexes associated with breastfeeding.

    Science.gov (United States)

    Marín Gabriel, Miguel A; Olza Fernández, Ibone; Malalana Martínez, Ana M; González Armengod, Carmen; Costarelli, Valeria; Millán Santos, Isabel; Fernández-Cañadas Morillo, Aurora; Pérez Riveiro, Pilar; López Sánchez, Francisco; García Murillo, Lourdes

    2015-05-01

    Several synthetic peptide manipulations during the time surrounding birth can alter the specific neurohormonal status in the newborn brain. This study is aimed at assessing whether intrapartum oxytocin administration has any effect on primitive neonatal reflexes and determining whether such an effect is dose-dependent. A cohort prospective study was conducted at a tertiary hospital. Mother-infant dyads who received intrapartum oxytocin (n=53) were compared with mother-infant dyads who did not receive intrapartum oxytocin (n=45). Primitive neonatal reflexes (endogenous, antigravity, motor, and rhythmic reflexes) were quantified by analyzing videotaped breastfeeding sessions in a biological nurturing position. Two observers blind to the group assignment and the oxytocin dose analyzed the videotapes and assesed the newborn's state of consciousness according to the Brazelton scale. The release of all rhythmic reflexes (p=0.01), the antigravity reflex (p=0.04), and total primitive neonatal reflexes (p=0.02) in the group exposed to oxytocin was lower than in the group not exposed to oxytocin. No correlations were observed between the dose of oxytocin administered and the percentage of primitive neonatal reflexes released (r=0.03; p=0.82). Intrapartum oxytocin administration might inhibit the expression of several primitive neonatal reflexes associated with breastfeeding. This correlation does not seem to be dose-dependent.

  12. Reflexive Aero Structures for Enhanced Survivability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) will develop an advanced reflexive structure technology system to increase the survivability of future systems constructed of...

  13. Neural reflexes in inflammation and immunity

    National Research Council Canada - National Science Library

    Andersson, Ulf; Tracey, Kevin J

    2012-01-01

    .... Development of advanced neurophysiological and immunological techniques recently enabled the study of reflex neural circuits that maintain immunological homeostasis, and are essential for health in mammals...

  14. [Clinical relevance of cardiopulmonary reflexes in anesthesiology].

    Science.gov (United States)

    Guerri-Guttenberg, R A; Siaba-Serrate, F; Cacheiro, F J

    2013-10-01

    The baroreflex, chemoreflex, pulmonary reflexes, Bezold-Jarisch and Bainbridge reflexes and their interaction with local mechanisms, are a demonstration of the richness of cardiovascular responses that occur in human beings. As well as these, the anesthesiologist must contend with other variables that interact by attenuating or accentuating cardiopulmonary reflexes such as, anesthetic drugs, surgical manipulation, and patient positioning. In the present article we review these reflexes and their clinical relevance in anesthesiology. Copyright © 2012 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

  15. Structural cure for reflex syncope?

    Science.gov (United States)

    Sulke, Neil; Eysenck, William; Badiani, Sveeta; Furniss, Stephen

    2016-01-20

    The ROX Coupler is a device that allows creation of a central arteriovenous anastomosis at the iliac level. The device has been shown to improve exercise capacity in patients with chronic obstructive pulmonary disease and is CE marked for the treatment of resistant and uncontrolled hypertension. Reflex syncope is a challenging clinical condition with limited proven therapeutic options. We describe the resolution of symptoms and tilt table response of a patient who underwent insertion of a ROX Coupler to treat hypertension, and also incidentally had pre-existing vasodepressor syncope. 2016 BMJ Publishing Group Ltd.

  16. Leukocoria and the red reflex test

    Directory of Open Access Journals (Sweden)

    Mirna Yae Yassuda Tamura

    2009-09-01

    Full Text Available Until recently, the ophthalmologic examination of newborns in maternity hospitals was not a priority; even today, few hospitals perform this examination adequately. Consequences may be disastrous, because by the time eye alterations are found, the child may have developed permanent loss of visual acuity. The ophthalmologic examination in nurseries, carried out by neonatologists, permits an early diagnosis and referral for effective therapy and adequate development of vision. This study underlines the importance of the red reflex test in newborns and presents the main causes of leukocoria (cataract, retinoblastoma, and retinal and vitreous diseases to alert pediatricians and neonatologists about this condition. Special emphasis is given to retinoblastoma, a condition affecting 1/14,000 to 1/20,000 live newborns; genetic, clinical, diagnostic, and therapeutic aspects are presented. Early diagnosis of retinoblastoma is essential for reducing morbidity and mortality.

  17. Vestibulospinal reflexes as a function of microgravity

    Science.gov (United States)

    Reschke, M. F.; Homick, J. L.; Anderson, D. J.

    1984-01-01

    Data from previous manned space flights suggest that an exposure to microgravity produces significant alterations in vestibular, neuromuscular, and related sensory system functions. It is possible that the observed changes are a function of adaptation induced by altered otolith input. An experiment in Spacelab 1 was conducted with the aim to study this adaptation as it occurred in flight and after flight, and to relate the observed changes to mechanisms underlying space motion sickness. The concept was explored by making use of the anatomic pathway which links the otolith organs and spinal motoneurons. The overall sensitivity of the spinal motoneurons was tested by two related methods. One method involves the electrical excitation of neural tissue and the recording of vestibulospinal reflexes in conjunction with a brief linear acceleration. The second method is concerned with measurements of dynamic postural ataxia. Results suggest that more than a single time constant may be involved in man's ability to return to baseline values.

  18. Axon reflexes in human cold exposed fingers

    NARCIS (Netherlands)

    Daanen, H.A.M.; Ducharme, M.B.

    2000-01-01

    Exposure of fingers to severe cold induces cold induced vasodilation (CIVD). The mechanism of CIVD is still debated. The original theory states that an axon reflex causes CIVD. To test this hypothesis, axon reflexes were evoked by electrical stimulation of the middle fingers of hands immersed in

  19. Tactile Sensing Reflexes for Advanced Prosthetic Hands

    Science.gov (United States)

    2016-10-01

    custom controller that enables a biomimetic reflex to improve the speed and ability to perform fragile grasping tasks for amputees. This hand would reduce...sensors and biomimetic reflexes have been demonstrated to improve the speed and accuracy of bimanual, fragile grasping tasks when compared to the same

  20. Cardiovascular regulation by skeletal muscle reflexes in health and disease

    National Research Council Canada - National Science Library

    Murphy, Megan N; Mizuno, Masaki; Mitchell, Jere H; Smith, Scott A

    2011-01-01

    .... These neurally mediated cardiovascular adjustments to physical activity are regulated, in part, by a peripheral reflex originating in contracting skeletal muscle termed the exercise pressor reflex...

  1. Reflexive criteria of sociological research

    Directory of Open Access Journals (Sweden)

    R T Ubaydullaeva

    2014-12-01

    Full Text Available The article is devoted to the sociological criteria of explaining the way of thinking and actions of subjects, their spiritual and moral positions and intellectual forces that form the laws of social life. The author seeks to adapt such categories as ‘meaning of life’, ‘human dignity’, ‘rationality’ etc. for the purposes of sociological analysis by methodological construction of some real life dichotomies such as ‘subjective meaning and social function’, ‘the real and the ideal’, ‘the demanded and the excluded’. Thus, the author studies economic, political and technical processes in terms of both positivity and negativity of social interaction and states that given the increasing differentiation of the society and the contradictory trends of social development the reflexive criteria that take into account the socio-cultural nature of the man help to find one’s own model of development.

  2. Reflex sympathetic dystrophy in childhood.

    Science.gov (United States)

    Tekgül, Hasan; Serdaroglu, Guil; Uyar, Meltem; Tütüncüoglu, Sarenur

    2002-04-01

    Reflex sympathetic dystrophy is characterized by constant burning pain and hyperesthesia in an extremity. Lower extremities are usually affected. Pain is accompanied by swelling, sweating, vasomotor instability and sometimes trophic changes. There may be a history of minor injury or not. Muscle spasms, myoclonus or focal dystonia may occur. Diffuse pain, loss of function and autonomic dysfunction are three main criteria suggested for diagnosis. Symptoms can last a few days to as long as a year. In this report we present a girl with multiple limb involvement of stage I RSD. The sympathetic skin responses were tested during a remission period. She had milder attacks with a recurrence rate of 4 per year in the following three years from onset.

  3. Achilles tendon reflex measuring system

    Science.gov (United States)

    Szebeszczyk, Janina; Straszecka, Joanna

    1995-06-01

    The examination of Achilles tendon reflex is widely used as a simple, noninvasive clinical test in diagnosis and pharmacological therapy monitoring in such diseases as: hypothyroidism, hyperthyroidism, diabetic neuropathy, the lower limbs obstructive angiopathies and intermittent claudication. Presented Achilles tendon reflect measuring system is based on the piezoresistive sensor connected with the cylinder-piston system. To determinate the moment of Achilles tendon stimulation a detecting circuit was used. The outputs of the measuring system are connected to the PC-based data acquisition board. Experimental results showed that the measurement accuracy and repeatability is good enough for diagnostics and therapy monitoring purposes. A user friendly, easy-to-operate measurement system fulfills all the requirements related to recording, presentation and storing of the patients' reflexograms.

  4. Recreational soccer can improve the reflex response to sudden trunk loading among untrained women

    DEFF Research Database (Denmark)

    Pedersen, Mogens T; Randers, Morten B; Skotte, Jørgen H

    2009-01-01

    A slower reflex response to sudden trunk loading (SL) has been shown to increase future risk of low back injuries in healthy subjects, and specific readiness training can improve the response to SL among healthy subjects. The purpose of the study was to investigate the effect of recreational soccer...... stopping of the forward movement of the trunk (stopping time) decreased (p football training includes a high number of sudden loadings of the upper body and can improve...... the reflex response to SL. The faster reflex response indicates that soccer training can reduce the risk of low back injuries....

  5. Trigemino-Cardiac Reflex: A Phenomenon Neglected in Maxillofacial Surgery?

    Science.gov (United States)

    Joshi, Udupikrishna M; Munnangi, Ashwini; Shah, Kundan; Patil, Satishkumar G; Thakur, Nitin

    2017-06-01

    Trigemino-cardiac reflex is a physiologic response of the body to pressure effects in the region of distribution of the trigeminal nerve. Oral and maxillofacial surgical procedures can induce the development of this reflex, which leads to significant changes in the heart rate and sinus rhythms. This study intends to evaluate the effects of this reflex in patients with facial fractures and its subsequent management. A total of thirty-seven patients with facial fractures who reported to the Department of Oral and Maxillofacial Surgery at Basaveswar Teaching and General Hospital, Gulbarga during a period from July 2015-March 2016 were considered for the study. A male preponderance is observed with the most susceptible age group being 21-30 years. Twenty-three patients sustained mid-facial fractures alone, nine patients had isolated mandible fractures and five patients had fractures of both the mid-face and mandible. A relative bradycardia was observed in the patients with mid-facial trauma, both at the time of presentation and also during the surgical reduction of midfacial fractures which improved after completion of procedure in most of the patients. However, in two patients, the bradycardia progressed to a cardiac asystole during midface manipulation which required immediate halt of the procedure and intravenous administration of atropine. Trigeminocardiac reflex though physiologic, which usually tends to subside without complications is not to be neglected in the surgeries of the maxillofacial skeleton. A propensity for unforeseen complications due to this reflex has to be avoided by meticulous monitoring of the ECG.

  6. Kinematic and kinetic analysis of the inter- and intra-applicator assessment of the Babinski reflex.

    Science.gov (United States)

    Dafkin, C; Green, A; Kerr, S; Raymond, A; Veliotes, D; Elvin, A; Olivier, B; McKinon, W

    2014-11-01

    The first aim was to quantify variability in the mechanical technique used by neurologists to elicit the Babinski reflex. The second aim of the study was to assess if the mechanical technique is an important determinant of the subsequent reflex response. In this study, twelve neurologists elicited the Babinski reflex five times on the same foot of the same participant using a special reflex hammer which recorded the force and duration of the stroke. Hallux movement, tibialis anterior maximum EMG amplitude and pain felt by the participant for each stroke were recorded. A large inter- and intra-applicator variability was shown amongst the neurologists. The change in hallux angle was significantly correlated with the duration of the stroke (R(2)=0.18, PBabinski reflex. These results indicate that there was substantial variation when performing the Babinski reflex test within and between neurologists which could lead to differences in the resultant reflex and therefore may affect subsequent diagnoses. Copyright © 2014. Published by Elsevier SAS.

  7. Influence of the cuff pressure on the swallowing reflex in tracheostomized intensive care unit patients.

    Science.gov (United States)

    Amathieu, R; Sauvat, S; Reynaud, P; Slavov, V; Luis, D; Dinca, A; Tual, L; Bloc, S; Dhonneur, G

    2012-10-01

    Because recovery of an efficient swallowing reflex is a determining factor for the recovery of airway protective reflexes, we have studied the influence of the tracheostomy tube cuff pressure (CP) on the swallowing reflex in tracheotomized patients. Twelve conscious adult intensive care unit (ICU) patients who had been weaned from mechanical ventilation were studied. Simultaneous EMG of the submental muscles with measurement of peak activity (EMGp) and amplitude of laryngeal acceleration (ALA) were performed during reflex swallows elicited by pharyngeal injection of distilled water boluses during end expiration. After cuff deflation, characteristics of the swallowing reflex (latency time: LaT, EMGp, and ALA) were measured at CPs of 5, 10, 15, 20, 25, 30, 40, 50, and 60 cm H(2)O. LaT and CP were linearly related (P<0.01). CP was inversely correlated (P<0.01) to both ALA and EMGp. We demonstrated that LaT, EMGp, and ALA of the swallowing reflex were influenced by tracheostomy tube CP. The swallowing reflex was progressively more difficult to elicit with increasing CP and when activated, the resulting motor swallowing activity and efficiency at elevating the larynx were depressed.

  8. Modulation of H-Reflex Depression with Paired-Pulse Stimulation in Healthy Active Humans

    Directory of Open Access Journals (Sweden)

    Preeti D. Oza

    2017-01-01

    Full Text Available Depression of the Hoffman reflex (H-reflex is used to examine spinal control mechanisms during exercise, fatigue, and vibration and in response to training. H-reflex depression protocols frequently use trains of stimuli; this is time-consuming and prevents instantaneous assessment of motor neuronal excitability. The purpose of this study was to determine if paired-pulse H-reflex depression is reproducible and whether paired-pulse stimulation adequately estimates the depression induced by the more traditional ten-pulse train. H-reflexes were elicited via ten-pulse trains at 0.1, 0.2, 1, 2, and 5 Hz in ten neurologically intact individuals on two separate days. We measured the depression elicited by the second pulse (H2 and the mean depression elicited by pulses 2–10 (Hmean. H2 was consistent at all frequencies on both days (r2 = 0.97, p0.05. The results indicate that paired-pulse H-reflex depression has high between-day reliability and yields depression estimates that are comparable to those obtained via ten-pulse trains. Paired-pulse H-reflex depression may be especially useful for studies that require rapid assessment of motor neuronal excitability, such as during exercise, fatigue, and vibration, or to establish recovery curves following inhibition.

  9. Brainstem reflexes in patients with familial dysautonomia.

    Science.gov (United States)

    Gutiérrez, Joel V; Norcliffe-Kaufmann, Lucy; Kaufmann, Horacio

    2015-03-01

    Several distinctive clinical features of patients with familial dysautonomia (FD) including dysarthria and dysphagia suggest a developmental defect in brainstem reflexes. Our aim was to characterize the neurophysiological profile of brainstem reflexes in these patients. We studied the function of sensory and motor trigeminal tracts in 28 patients with FD. All were homozygous for the common mutation in the IKAP gene. Each underwent a battery of electrophysiological tests including; blink reflexes, jaw jerk reflex, masseter silent periods and direct stimulation of the facial nerve. Responses were compared with 25 age-matched healthy controls. All patients had significantly prolonged latencies and decreased amplitudes of all examined brainstem reflexes. Similar abnormalities were seen in the early and late components. In contrast, direct stimulation of the facial nerve revealed relative preservation of motor responses. The brainstem reflex abnormalities in FD are best explained by impairment of the afferent and central pathways. A reduction in the number and/or excitability of trigeminal sensory axons is likely the main problem. These findings add further evidence to the concept that congenital mutations of the elongator-1 protein (or IKAP) affect the development of afferent neurons including those carrying information for the brainstem reflex pathways. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  10. A near catastrophe from trigeminocardiac reflex

    Directory of Open Access Journals (Sweden)

    Parmod K Bithal

    2017-01-01

    Full Text Available Trigeminocardiac reflex is a brainstem reflex that results from stimulation of any branch of the trigeminal nerve along its course. It produces a constellation of signs and symptoms decrease in blood pressure (BP and heart rate, dysrhythmias, apnoea and increased gastric motility. We present a case of 80-year-old female patient who developed alarming hypotension and bradycardia during craniotomy for meningioma excision resulting from this reflex. In the face of refractory hypotension despite administering ephedrine and phenylephrine, we had to resort to adrenaline to restore her normal BP.

  11. The Reflexes of the Fundus Oculi

    Science.gov (United States)

    Ballantyne, A. J.

    1940-01-01

    The fundus reflexes reveal, in a manner not yet completely understood, the texture and contour of the reflecting surfaces and the condition of the underlying tissues. In this way they may play an important part in the biomicroscopy of the eye. The physiological reflexes are seen at their best in the eyes of young subjects, in well-pigmented eyes, with undilated pupils and with emmetropic refraction. Their absence during the first two decades, or their presence after the forties, their occurrence in one eye only, their appearance, disappearance or change of character should suggest the possibility of some pathological state. The investigation and interpretation of the reflexes are notably assisted by comparing the appearances seen with long and short wave lights such as those of the sodium and mercury vapour lamps, in addition to the usual ophthalmoscopic lights. Most of the surface reflexes disappear in the light of the sodium lamp, sometimes revealing important changes in the deeper layers of the retina and choroid. The physiological reflexes, chiefly formed on the surface of the internal limiting membrane, take the forms of the familiar watered silk or patchy reflexes, the peri-macular halo, the fan reflex in the macular depression and the reflex from the foveal pit. The watered silk or patchy reflexes often show a delicate striation which follows the pattern of the nerve-fibre layer, or there may be a granular or criss-cross texture. Reflexes which entirely lack these indications of “texture” should be considered as possibly pathological. This applies to the “beaten metal” reflexes and to those formed on the so-called hyaloid membrane. The occurrence of physiological reflexes in linear form is doubtful, and the only admittedly physiological punctate reflexes are the so-called Gunn's dots. Surface reflexes which are broken up into small points or flakes are pathological, and are most frequently seen in the central area of the fundus in cases of pigmentary

  12. Reflecting on Reflexivity: Reflexive Textual Practices in Organization and Management Theory

    OpenAIRE

    Alvesson, M.; Hardy, C; B. Harley

    2008-01-01

    This paper identifies four sets of textual practices that researchers in the field of organization and management theory (OMT) have used in their attempts to be reflexive. We characterize them as multi-perspective, multi-voicing, positioning and destabilizing. We show how each set of practices can help to produce reflexive research, but also how each embodies limitations and paradoxes. Finally, we consider the interplay among these sets of practices to develop ideas for new avenues for reflex...

  13. Measurement of tendon reflexes by surface electromyography in normal subjects

    NARCIS (Netherlands)

    Stam, J.; van Crevel, H.

    1989-01-01

    A simple method for measuring the tendon reflexes was developed. A manually operated, electronic reflex hammer was applied that enabled measurement of the strength of tendon taps. Reflex responses were recorded by surface electromyography. Stimulus-response relations and latencies of tendon reflexes

  14. Portraying Reflexivity in Health Services Research.

    Science.gov (United States)

    Rae, John; Green, Bill

    2016-09-01

    A model is proposed for supporting reflexivity in qualitative health research, informed by arguments from Bourdieu and Finlay. Bourdieu refers to mastering the subjective relation to the object at three levels-the overall social space, the field of specialists, and the scholastic universe. The model overlays Bourdieu's levels of objectivation with Finlay's three stages of research (pre-research, data collection, and data analysis). The intersections of these two ways of considering reflexivity, displayed as cells of a matrix, pose questions and offer prompts to productively challenge health researchers' reflexivity. Portraiture is used to show how these challenges and prompts can facilitate such reflexivity, as illustrated in a research project. © The Author(s) 2016.

  15. Entrepreneurship Teaching Conducted as Strategic Reflexive Conversation

    DEFF Research Database (Denmark)

    Kristiansson, Michael

    The paper intends exploring and ascertaining whether the concept of strategic reflexive conversation can profitably be applied to entrepreneurship. As a start, a process of conceptualisation is undertaken, which is instrumental in placing the notion of strategic reflexive conversation...... into a knowledge management perspective. Strategic reflexive conversation is presented in an enhanced and updated version, which is contrasted to entrepreneurship through reflection. The findings indicate and it can be concluded that, with some important reservations, strategic reflexive conversation can...... advantageously, and on a pilot basis, be applied to entrepreneurship in practical environments and within the framework of entrepreneurship-centred teaching. The present theoretical investigation is solely of an introductory nature and steps are considered that can lead to the planning of additional exploratory...

  16. Somatosensory and acoustic brain stem reflex myoclonus.

    OpenAIRE

    Shibasaki, H; Kakigi, R; Oda, K; Masukawa, S

    1988-01-01

    A patient with brain stem reflex myoclonus due to a massive midbrain infarct was studied electrophysiologically. Myoclonic jerks were elicited at variable latencies by tapping anywhere on the body or by acoustic stimuli, and mainly involved flexor muscles of upper extremities. The existence of convergence of somatosensory and acoustic inputs in the brain stem was suggested. This myoclonus seemed to be mediated by a mechanism similar to the spino-bulbo-spinal reflex.

  17. Stretch reflex and servo action in a variety of human muscles.

    Science.gov (United States)

    Marsden, C D; Merton, P A; Morton, H B

    1976-07-01

    1. In the long flexor of the thumb the latency of the stretch reflex and of other manifestations of servo action is some 45 msec, roughly double the latency of a finger jerk. 2. Tendon jerks are feeble or absent in the long flexor of the thumb even in subjects with brisk long-latency stretch reflexes in this muscle. This, and other facts, suggests that the nervous mechanism of the tendon jerk is different from that of the stretch reflex. 3. A muscle that has feeble tendon jerks may show a late component in the response to a tendon tap, with a latency similar to that of the long-latency stretch reflex. 4. On the hypothesis that the excess latency of the stretch reflex over that of a tendon jerk is because the stretch reflex employs a cortical rather than a spinal arc, the excess would be expected to be larger in magnitude for the long flexor of the big toe and smaller for the jaw closing muscles. This is confirmed, 5. An alternative hypothesis that the long latency of stretch reflexes in thumb and toe is because they are excited by slow-conducting afferents is made improbable by the finding that stretch reflexes with an equal or greater excess latency are also found in proximal arm muscles. 6. The long-latency stretch reflex in proximal muscles was seen most distinctly in a healthy subject who happened to have feeble or absent tendon jerks. In ordinary subjects there is often a large, short-latency, presumably spinal component of the stretch reflex in proximal muscles; and short-latency responses to halt and release are also seen, The significance of this spinal latency servo action in proximal muscles remains to be explored. 7. The Discussion argues that the available data on conduction time to and from the cerebral cortex are compatible with the hypothesis that the long-latency component of the stretch reflex uses a transcortical reflex arc, and that none of the experiments described in the present paper are inimical to this view.

  18. Reflexive convention: civil partnership, marriage and family.

    Science.gov (United States)

    Heaphy, Brian

    2017-09-14

    Drawing on an analysis of qualitative interview data from a study of formalized same-sex relationships (civil partnerships) this paper examines the enduring significance of marriage and family as social institutions. In doing so, it intervenes in current debates in the sociology of family and personal life about how such institutions are undermined by reflexivity or bolstered by convention. Against the backdrop of dominating sociological frames for understanding the links between the changing nature of marriage and family and same-sex relationship recognition, the paper analyses the diverse and overlapping ways (including the simple, relational, strategic, ambivalent and critical ways) in which same-sex partners reflexively constructed and engaged with marriage and family conventions. My analysis suggests that instead of viewing reflexivity and convention as mutually undermining, as some sociologists of family and personal life do, it is insightful to explore how diverse forms of reflexivity and convention interact in everyday life to reconfigure the social institutions of marriage and family, but do not undermine them as such. I argue the case for recognizing the ways in which 'reflexive convention', or reflexive investment in convention, contributes to the continuing significance of marriage and family as social institutions. © London School of Economics and Political Science 2017.

  19. The passive of reflexive verbs in Icelandic

    Directory of Open Access Journals (Sweden)

    Hlíf Árnadóttir

    2011-10-01

    Full Text Available The Reflexive Passive in Icelandic is reminiscent of the so-called New Passive (or New Impersonal in that the oblique case of a passivized object NP is preserved. As is shown by recent surveys, however, speakers who accept the Reflexive Passive do not necessarily accept the New Passive, whereas conversely, speakers who accept the New Passive do also accept the Reflexive Passive. Based on these results we suggest that there is a hierarchy in the acceptance of passive sentences in Icelandic, termed the Passive Acceptability Hierarchy. The validity of this hierarchy is confirmed by our diachronic corpus study of open access digital library texts from Icelandic journals and newspapers dating from the 19th and 20th centuries (tímarit.is. Finally, we sketch an analysis of the Reflexive Passive, proposing that the different acceptability rates of the Reflexive and New Passives lie in the argument status of the object. Simplex reflexive pronouns are semantically dependent on the verbs which select them, and should therefore be analyzed as syntactic arguments only, and not as semantic arguments of these verbs.

  20. Long-latency spinal reflexes in humans.

    Science.gov (United States)

    Darton, K; Lippold, O C; Shahani, M; Shahani, U

    1985-06-01

    Stretching human muscles with a mechanical device gave rise to multiple peaks in the rectified and averaged electromyogram. In the first dorsal interosseous the latency of the first peak (M1) was 32.4 +/- 2.4 ms (SD) and the latency of the second peak (M2) was 55.1 +/- 11.3 ms, in both cases measured from the time of the stimulus to the take-off point of the peak. Often a third peak (M3) was seen, having a considerably longer latency. The origin of peak M1 was considered to be in the stretch reflex arc because of its latency and its invariable association with muscle movement. Peak M2 was due to stimulation of afferent terminals in the skin and/or subcutaneous tissues by the mechanical device producing the muscle stretch. The conduction velocity of the pathway involved in the generation of the M1 component is the same as that for M2. This implies that central processing in the spinal cord delays the M2 response. The M2 mechanism does not involve a transcortical (long-loop) pathway because in foot muscles the M1-M2 delay remains the same as is found for hand muscles, although M1 latency is prolonged (to 39.4 +/- 6.2 ms for extensor digitorum longus). This indicates that there is not time for M2 impulses to traverse a pathway any longer than that passing to and from the spinal cord.

  1. On the Second Language Acquisition of Spanish Reflexive Passives and Reflexive Impersonals by French- and English-Speaking Adults

    Science.gov (United States)

    Tremblay, Annie

    2006-01-01

    This study, a partial replication of Bruhn de Garavito (1999a; 1999b), investigates the second language (L2) acquisition of Spanish reflexive passives and reflexive impersonals by French- and English-speaking adults at an advanced level of proficiency. The L2 acquisition of Spanish reflexive passives and reflexive impersonals by native French and…

  2. On the second language acquisition of Spanish reflexive passives and reflexive impersonals by French- and English-speaking adults

    OpenAIRE

    Tremblay, Annie

    2006-01-01

    Abstract This study, a partial replication of Bruhn de Garavito (1999a; 1999b), investigates the second language (L2) acquisition of Spanish reflexive passives and reflexive impersonals by French- and English-speaking adults at an advanced level of proficiency. The L2 acquisition of Spanish reflexive passives and reflexive impersonals by native French and English speakers instantiates a potential ...

  3. Recurrent and migratory reflex sympathetic dystrophy in children.

    Science.gov (United States)

    Tong, H C; Nelson, V S

    2000-01-01

    Reflex sympathetic dystrophy is a syndrome characterized by superficial pain and tenderness associated with swelling, vasomotor instability, and dystrophic changes of the skin. In children, it is rarely reported and is felt to have a more benign and self-limited course. This case illustrates that, in children, reflex sympathetic dystrophy can occur without any previous history of trauma, and may be recurrent and migratory. A review of the literature is included. An 11-year-old girl, with no history of trauma, presented in 1992 with spontaneous onset of right leg pain. She was diagnosed with reflex sympathetic dystrophy, and she was treated unsuccessfully with oral medications. Her symptoms then resolved in 2 weeks after receiving epidural anaesthesia and aggressive physical therapy. Over the next 5 years, she presented to the paediatric rehabilitation clinic three times with recurrent RSD in her bilateral arms. The first two times were refractory to conservative management and resolved with four stellate ganglion blocks. The third recurrence persisted with three stellate ganglion blocks and resolved with gabapentin.

  4. A range of different stretch reflex responses in the human thumb.

    Science.gov (United States)

    Brown, T I; Rack, P M; Ross, H F

    1982-11-01

    1. Imposed sinusoids were used to assess the resistance to movement at the thumb interphalangeal joint.2. The resistance to high-frequency movements (> 12 Hz) increased when the subject exerted a large voluntary flexing force; this increase was attributable to a greater non-reflex resistance of the contracting flexor muscles. This resistance was essentially ;visco-elastic', and the force was phase-advanced on joint position. At moderately large forces (up to half maximal), however, the resistance changed with changing frequency, and over a range 4-12 Hz the vectors which represented joint stiffness described the wide path that is characteristic of an active stretch reflex (Brown, Rack & Ross, 1982a). At frequencies between about 4 and 6 Hz the force was sometimes phase-delayed on position, and the joint exhibited a negative viscous stiffness. When the voluntary flexing force was very large the reflex contributed less to the resisting force, which was then phase-advanced on position at all frequencies of movement.3. Large amplitude movements did not generate correspondingly large reflex responses; as the amplitude of movement was increased, the reflex component of the resisting force became relatively smaller and the total resisting force was then phase-advanced on joint position at all frequencies.4. The reflex component of the resisting force (as indicated by the excursion of the joint stiffness vectors) varied from subject to subject and from time to time; the reflex usually became more active late in an experiment when the subject had exerted flexing forces against the imposed movement for some minutes. Extreme fatigue, however, diminished the amount of reflex force.5. In some subjects the joint-stiffness records indicated a particularly vigorous reflex response at 8-11 Hz, in contrast to a rather feeble response at 6 or 7 Hz. It is suggested that the reflex pathways then had a relatively low impedance to afferent signals that were modulated at 8-11 Hz, related

  5. Reflex and Non-Reflex Torque Responses to Stretch of the Human Knee Extensors

    National Research Council Canada - National Science Library

    Mrachacz-Kersting, N

    2001-01-01

    .... The quadriceps muscles were stretched at various background torques, produced either voluntarily or electrically and thus the purely reflex-mediated torque could be calculated. The contribution of the reflex mediated stiffness initially low, increased with increasing background torques for the range of torques investigated.

  6. Evidence for sustained cortical involvement in peripheral stretch reflex during the full long latency reflex period

    NARCIS (Netherlands)

    Perenboom, M.J.L.; Van de Ruit, M.; de Groot, J.H.; Schouten, A.C.; Meskers, C.G.M.

    2015-01-01

    Adaptation of reflexes to environment and task at hand is a key mechanism in optimal motor control, possibly regulated by the cortex. In order to locate the corticospinal integration, i.e. spinal or supraspinal, and to study the critical temporal window of reflex adaptation, we combined transcranial

  7. Soleus H-Reflex Operant Conditioning Changes The H-Reflex Recruitment Curve

    Science.gov (United States)

    Thompson, Aiko K.; Chen, Xiang Yang; Wolpaw, Jonathan R.

    2012-01-01

    Introduction Operant conditioning can gradually change the human soleus H-reflex. The protocol conditions the reflex near M-wave threshold. This study examined its impact on the reflexes at other stimulus strengths. Methods H-reflex recruitment curves were obtained before and after a 24-session exposure to an up-conditioning (HRup) or down-conditioning (HRdown) protocol and were compared. Results In both HRup and HRdown subjects, conditioning affected the entire H-reflex recruitment curve. In 5 of 6 HRup and 3 of 6 HRdown subjects, conditioning elevated (HRup) or depressed (HRdown), respectively, the entire curve. In the other HRup subject or the other 3 HRdown subjects, the curve was shifted to the left or to the right, respectively. Discussion H-reflex conditioning does not simply change the H-reflex to a stimulus of particular strength; it also changes the H-reflexes to stimuli of different strengths. Thus, it is likely to affect many actions in which this pathway participates. PMID:23281107

  8. Reflex sympathetic dystrophy: changing concepts and taxonomy.

    Science.gov (United States)

    Stanton-Hicks, M; Jänig, W; Hassenbusch, S; Haddox, J D; Boas, R; Wilson, P

    1995-10-01

    We present a revised taxonomic system for disorders previously called reflex sympathetic dystrophy (RSD) and causalgia. The system resulted from a special consensus conference that was convened on this topic and is based upon the patient's history, presenting symptoms, and findings at the time of diagnosis. The disorders are grouped under the umbrella term CRPS: complex regional pain syndrome. This overall term, CRPS, requires the presence of regional pain and sensory changes following a noxious event. Further, the pain is associated with findings such as abnormal skin color, temperature change, abnormal sudomotor activity, or edema. The combination of these findings exceeds their expected magnitude in response to known physical damage during and following the inciting event. Two types of CRPS have been recognized: type I, corresponds to RSD and occurs without a definable nerve lesion, and type II, formerly called causalgia refers to cases where a definable nerve lesion is present. The term sympathetically maintained pain (SMP) was also evaluated and considered to be a variable phenomenon associated with a variety of disorders, including CRPS types I and II. These revised categories have been included in the 2nd edition of the IASP Classification of Chronic Pain Syndromes.

  9. Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle.

    Science.gov (United States)

    Hayes, Bradley T; Hicks-Little, Charlie A; Harter, Rod A; Widrick, Jeffrey J; Hoffman, Mark A

    2009-12-01

    Hayes BT, Hicks-Little CA, Harter RA, Widrick JJ, Hoffman MA. Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle. To determine the day-to-day reliability of Hoffmann reflex (H-reflex) gain and presynaptic inhibition of spinal reflexes in the human soleus muscle. Controlled trial. Research laboratory. Volunteers (N=30; mean +/- SD age, 23.4+/-3.9y; height, 175.64+/-10.87cm; mass, 84.50+/-24.18kg) with no history of lower extremity pathology and/or injury participated. Subjects lay prone with the head, shoulders, arms, and hips supported in a static position by a massage body pillow and the ankle positioned at 90 degrees . Recording electrodes were placed over the soleus and tibialis anterior muscle bellies, and the stimulating electrodes were positioned over the tibial nerve in the popliteal space and the common peroneal nerve near the fibular head. The H-reflex and motor wave recruitment curves were then measured and recorded. Presynaptic inhibition was also assessed in the soleus muscle, and a conditioning stimulation of the common peroneal nerve (1 x motor threshold = motor threshold) was used prior to soleus H-reflex measurement. Two testing sessions took place between 2 and 7 days, and each session occurred at the same time of day. Assessments of H-reflex gain and presynaptic inhibition yielded test-retest reliability of R equal to . 95 and .91, respectively. Measures of presynaptic inhibition and H-reflex gain (H slope/M slope) in the human soleus muscle are consistent and reliable day to day.

  10. Depression and recovery of reflex amplitude during electrical stimulation after spinal cord injury.

    Science.gov (United States)

    Clair-Auger, J M; Lagerquist, O; Collins, D F

    2013-04-01

    The aim of this study was to quantify, for the first time, H-reflexes evoked during prolonged trains of wide-pulse neuromuscular electrical stimulation (WP-NMES) in individuals with chronic spinal cord injury (SCI). We hypothesised that after the first H-reflex, reflex amplitudes would be depressed (due to post-activation depression), but would recover and this recovery would be enhanced after a "burst" of 100 Hz WP-NMES. Soleus M-waves and H-reflexes evoked during WP-NMES (1 ms pulse width) of the tibial nerve were quantified in nine individuals with SCI. WP-NMES was delivered in two patterns: "constant-frequency" (15 or 20 Hz for 12 s) and "burst-like" (15-100-15 Hz or 20-100-20 Hz; 4 s each phase) at an intensity that evoked an M-wave between 10% and 15% of the maximal M-wave (M(max)). During constant frequency stimulation, after the initial depression from the first to the second H-reflex (1st: 57% M(max); 2nd: 25% M(max)), H-reflexes did not recover significantly and were 37% M(max) at the end of the stimulus train. During the burst-like pattern, after the initial depression (1st: 62% M(max); 2nd: 30%), reflexes recovered completely by the end of the stimulation (to 55% M(max)) as they were not significantly different from the first H-reflex. M-waves were initially depressed (1st: 12% M(max); 2nd: 7% M(max)) then did not change throughout the stimulation and were not significantly different between stimulation patterns. An analysis of covariance indicated that the depression in M-wave amplitude did not account for the depression in H-reflex amplitude. Relatively large H-reflexes were recorded during both patterns of NMES. The brief burst of 100 Hz stimulation restored H-reflexes to their initial amplitudes, effectively reversing the effects of post-activation depression. For individuals with chronic SCI, generating contractions through central pathways may help reduce muscle atrophy and produce contractions that are more fatigue-resistant for rehabilitation

  11. Sudden infant death triggered by dive reflex

    Science.gov (United States)

    Matturri, L; Ottaviani, G; Lavezzi, A M

    2005-01-01

    The dive reflex is the reflex mechanism most frequently considered in the aetiopathogenesis of sudden infant death syndrome (SIDS). This seems to persist in human beings as an inheritance from diver birds and amphibians. It has been reported that washing the face with cold water or plunging into cold water can provoke cardiac deceleration through the intervention of the ambiguus and the vagal dorsal nuclei. This report describes a case of SIDS that offers a unique insight into the role of the dive reflex in determining a lethal outcome. Examination of the brainstem on serial sections revealed severe bilateral hypoplasia of the arcuate nucleus and gliosis of the other cardiorespiratory medullary nuclei. The coronary and cardiac conduction arteries presented early atherosclerotic lesions. The possible role of parental cigarette smoking in the pathogenesis of arcuate nucleus hypoplasia and early coronary atherosclerotic lesions is also discussed. PMID:15623488

  12. Human investigations into the exercise pressor reflex

    DEFF Research Database (Denmark)

    Secher, Niels H; Amann, Markus

    2012-01-01

    . The importance of the exercise pressor reflex for tight cardiovascular regulation during dynamic exercise is supported by studies using pharmacological blockade of lower limb muscle afferent nerves. These experiments show attenuation of the increase in BP and cardiac output when exercise is performed......During exercise, neural input from skeletal muscles reflexly maintains or elevates blood pressure (BP) despite a maybe fivefold increase in vascular conductance. This exercise pressor reflex is illustrated by similar heart rate (HR) and BP responses to electrically induced and voluntary exercise...... of an increase in BP during exercise with paralysed legs manifests, although electrical stimulation of muscles enhances lactate release and reduces muscle glycogen. Thus, the exercise pressor reflex enhances sympathetic activity and maintains perfusion pressure by restraining abdominal blood flow, while brain...

  13. Descending Influences on Vestibulospinal and Vestibulosympathetic Reflexes

    Science.gov (United States)

    McCall, Andrew A.; Miller, Derek M.; Yates, Bill J.

    2017-01-01

    This review considers the integration of vestibular and other signals by the central nervous system pathways that participate in balance control and blood pressure regulation, with an emphasis on how this integration may modify posture-related responses in accordance with behavioral context. Two pathways convey vestibular signals to limb motoneurons: the lateral vestibulospinal tract and reticulospinal projections. Both pathways receive direct inputs from the cerebral cortex and cerebellum, and also integrate vestibular, spinal, and other inputs. Decerebration in animals or strokes that interrupt corticobulbar projections in humans alter the gain of vestibulospinal reflexes and the responses of vestibular nucleus neurons to particular stimuli. This evidence shows that supratentorial regions modify the activity of the vestibular system, but the functional importance of descending influences on vestibulospinal reflexes acting on the limbs is currently unknown. It is often overlooked that the vestibulospinal and reticulospinal systems mainly terminate on spinal interneurons, and not directly on motoneurons, yet little is known about the transformation of vestibular signals that occurs in the spinal cord. Unexpected changes in body position that elicit vestibulospinal reflexes can also produce vestibulosympathetic responses that serve to maintain stable blood pressure. Vestibulosympathetic reflexes are mediated, at least in part, through a specialized group of reticulospinal neurons in the rostral ventrolateral medulla that project to sympathetic preganglionic neurons in the spinal cord. However, other pathways may also contribute to these responses, including those that dually participate in motor control and regulation of sympathetic nervous system activity. Vestibulosympathetic reflexes differ in conscious and decerebrate animals, indicating that supratentorial regions alter these responses. However, as with vestibular reflexes acting on the limbs, little is known

  14. The stretch reflex and the contributions of C David Marsden

    Directory of Open Access Journals (Sweden)

    Kalyan B Bhattacharyya

    2017-01-01

    Full Text Available The stretch reflex or myotatic reflex refers to the contraction of a muscle in response to its passive stretching by increasing its contractility as long as the stretch is within physiological limits. For ages, it was thought that the stretch reflex was of short latency and it was synonymous with the tendon reflex, subserving the same spinal reflex arc. However, disparities in the status of the two reflexes in certain clinical situations led Marsden and his collaborators to carry out a series of experiments that helped to establish that the two reflexes had different pathways. That the two reflexes are dissociated has been proved by the fact that the stretch reflex and the tendon reflex, elicited by stimulation of the same muscle, have different latencies, that of the stretch reflex being considerably longer. They hypothesized that the stretch reflex had a transcortical course before it reached the spinal motor neurons for final firing. Additionally, the phenomenon of stimulus-sensitive cortical myoclonus lent further evidence to the presence of the transcortical loop where the EEG correlate preceded the EMG discharge. This concept has been worked out by later neurologists in great detail , and the general consensus is that indeed, the stretch reflex is endowed with a conspicuous transcortical component.

  15. The effect of elbow position on biceps tendon reflex.

    Science.gov (United States)

    Keles, Isik; Nilufer, Balci; Mehmet, Beyazova

    2004-09-01

    Testing of tendon (T) reflex is the basic method used in the diagnostic procedure of clinical neurology. Measurement of T reflexes precisely can be a valuable adjunct to clinical examination. Quantification of T reflexes may provide more accurate results. To analyze the effect of elbow position on biceps T reflex. A self-controlled clinical trial of biceps T reflex testing at the Electrophysiology Unit of the Department of Physical Medicine and Rehabilitation. Biceps T reflex was obtained utilizing a hand-held electronic reflex hammer in 50 extremities of 25 healthy volunteers and the effect of elbow position (at 90 degrees , 120 degrees and 150 degrees ) on reflex response was evaluated. Repeated-measures analysis of variance by the General Linear Model and Pearson correlation test procedures. Onset latency was significantly shorter at 120 degrees of elbow position. The maximum amplitude value of biceps T reflex was obtained at 90 degrees of elbow position. Onset latency of the reflex correlated significantly with the height and arm length but not with age. The electrophysiological measurement of T reflexes is an easy and useful method in the quantification of reflexes, supplying more objective data. However, when performing T reflex studies, the position of the extremity should be taken into consideration to achieve more reliable results.

  16. [The vegetative component of a conditioned reflex].

    Science.gov (United States)

    Ordzhonikadze, Ts A; Pkhakadze, L D

    1975-01-01

    Defensive and alimentary conditioned reflexes were studied on normal cats and cats with neural isolation of the neocortex. The cardiac component of the conditioned reflexes is elaborated in decorticated animals at a similar rate and is as steady as in normal cats. Motor conditioned reactions in decorticated cats are difficult to elaborate. Both in normal and decorticated cats unconditioned pain stimulation evokes tachycardia, while a conditioned signal, paired with this unconditioned stimulus, produces bradicardia. Ban assumption has been made that the primary conditioned reaction consists in the appearance of a certain emotional state which changes the cardiac rhythm in a typical way.

  17. Nonlinear stretch reflex interaction during cocontraction.

    Science.gov (United States)

    Carter, R R; Crago, P E; Gorman, P H

    1993-03-01

    1. We investigated the role of stretch reflexes in controlling two antagonist muscles acting at the interphalangeal joint in the normal human thumb. Reflex action was compared when either muscle contracted alone and during cocontraction. 2. The total torque of the flexor pollicis longus (FPL) and extensor pollicis longus (EPL) muscles was measured in response to an externally imposed extension of the interphalangeal joint. The initial joint angle and the amplitude of the extension were constant in all experiments, and the preload of the active muscle(s) was varied. Joint torque was measured at the peak of short-latency stretch reflex action during contraction of the FPL alone, contraction of the EPL alone, and during cocontraction. Incremental joint stiffness was calculated as the change in torque divided by the change in angle. 3. Incremental stiffness increased in proportion to the preload torque during single muscle contractions of either the FPL (lengthening disturbances) or the EPL (shortening disturbances). Thus stiffness was not regulated to a constant value in the face of varying loads for either single muscle stretch or release. 4. Incremental stiffness varied across the range of cocontraction levels while the net torque was maintained at approximately 0. Thus net torque alone did not determine the stiffness during cocontraction. 5. The contributions of each muscle to the net intrinsic torque during cocontraction were estimated by scaling the individual muscles' responses so that their sum gave the best fit (in a least-squares sense) to the cocontraction torque before reflex action. The solution is unique because the individual torques have opposite signs, but the stiffnesses add. This gave estimates of the initial torques of both muscles during cocontraction. 6. The contributions of the two muscles during cocontraction were used to estimate the active joint stiffness that would be expected if the two muscles were activated independently to the same levels

  18. Longitudinal performance of an implantable vestibular prosthesis.

    Science.gov (United States)

    Phillips, Christopher; Ling, Leo; Oxford, Trey; Nowack, Amy; Nie, Kaibao; Rubinstein, Jay T; Phillips, James O

    2015-04-01

    Loss of vestibular function may be treatable with an implantable vestibular prosthesis that stimulates semicircular canal afferents with biphasic pulse trains. Several studies have demonstrated short-term activation of the vestibulo-ocular reflex (VOR) with electrical stimulation. Fewer long-term studies have been restricted to small numbers of animals and stimulation designed to produce adaptive changes in the electrically elicited response. This study is the first large consecutive series of implanted rhesus macaque to be studied longitudinally using brief stimuli designed to limit adaptive changes in response, so that the efficacy of electrical activation can be studied over time, across surgeries, canals and animals. The implantation of a vestibular prosthesis in animals with intact vestibular end organs produces variable responses to electrical stimulation across canals and animals, which change in threshold for electrical activation of eye movements and in elicited slow phase velocities over time. These thresholds are consistently lower, and the slow phase velocities higher, than those obtained in human subjects. The changes do not appear to be correlated with changes in electrode impedance. The variability in response suggests that empirically derived transfer functions may be required to optimize the response of individual canals to a vestibular prosthesis, and that this function may need to be remapped over time. This article is part of a Special Issue entitled . Copyright © 2014 Elsevier B.V. All rights reserved.

  19. The acute effect of whole-body vibration on the hoffmann reflex.

    Science.gov (United States)

    Armstrong, W Jeffrey; Nestle, Holly N; Grinnell, David C; Cole, Lindsey D; Van Gilder, Erica L; Warren, Gabriel S; Capizzi, Elizabeth A

    2008-03-01

    The extent to which motoneuron pool excitability, as measured by the Hoffmann reflex (H-reflex), is affected by an acute bout of whole-body vibration (WBV) was recorded in 19 college-aged subjects (8 male and 11 female; mean age 19 +/- 1 years) after tibial nerve stimulation. H/M recruitment curves were mapped for the soleus muscle by increasing stimulus intensity in 0.2- to 1.0-volt increments with 10-second rest intervals between stimuli, until the maximal M-wave and H-reflex were obtained. After determination of Hmax and Mmax, the intensity necessary to generate an H-reflex approximately 30% of Mmax (mean 31.5% +/- 4.1%) was determined and used for all subsequent measurements. Fatigue was then induced by 1 minute of WBV at 40 Hz and low amplitude (2-4 mm). Successive measurements of the H-reflex were recorded at the test intensity every 30 seconds for 30 minutes post fatigue. All subjects displayed a significant suppression of the H-reflex during the first minute post-WBV; however, four distinct recovery patterns were observed among the participants (alpha = 0.50). There were no significant differences between genders across time (P = 0.401). The differences observed in this study cannot be explained by level or type training. One plausible interpretation of these data is that the multiple patterns of recovery may display variation of muscle fiber content among subjects. Future investigation should consider factors such as training specificity and muscle fiber type that might contribute to the differing H-reflex response, and the effect of WBV on specific performance measures should be interpreted with the understanding that there may be considerable variability among individuals. Recovery times and sample size should be adjusted accordingly.

  20. Comparison of Stretch Reflex Torques in Ankle Dorsiflexors and Plantarflexors

    National Research Council Canada - National Science Library

    Tung, J

    2001-01-01

    ...) ankle muscles, Pulse, step, and a combination of random perturbation and step inputs were used to identify the reflex and intrinsic contributions to the measured torque, TA reflex torques were very...

  1. How many theta roles in a reflexive verb?

    NARCIS (Netherlands)

    Dimitriadis, Alexis|info:eu-repo/dai/nl/304366455; Everaert, Martin|info:eu-repo/dai/nl/071746080

    2014-01-01

    While purely syntactic approaches to reflexivization have characterized reflexive verbs in terms of detransitivization, we show that there is a discrepancy between syntactic and semantic arity. Reflexive verbs are syntactically intransitive, but semantically they are two-place predicates: both

  2. Assessment of Primitive Reflexes in High-risk Newborns.

    Science.gov (United States)

    Sohn, Min; Ahn, Youngmee; Lee, Sangmi

    2011-12-01

    Assessment of primitive reflexes is one of the earliest, simplest, and most frequently used assessment tools among health care providers for newborns and young infants. However, very few data exist for high-risk infants in this topic. Among the various primitive reflexes, this study was undertaken particularly to describe the sucking, Babinski and Moro reflexes in high-risk newborns and to explore their relationships with clinical variables. This study is a cross-sectional descriptive study. Sixty seven high-risk newborns including full-term infants required intensive care as well as premature infants were recruited in a neonatal intensive care unit using convenient sampling method. The sucking, Babinski and Moro reflexes were assessed and classified by normal, abnormal and absence. To explore their relationships with clinical variables, birth-related variables, brain sonogram results, and behavioral state (the Anderson Behavioral State Scale, ABSS) and mental status (the Infant Coma Scale, ICS) were assessed. The sucking reflex presented a normal response most frequently (63.5%), followed by Babinski reflex (58.7%) and Moro reflex (42.9%). Newborns who presented normal sucking and Babinski reflex responses were more likely to have older gestational age, heavier birth and current weight, higher Apgar scores, shorter length of hospitalization, better respiratory conditions, and better mental status assessed by ICS, but not with Moro reflex. High risk newborns presented more frequent abnormal and absence responses of primitive reflex and the proportions of the responses varied by reflex. Further researches are necessary in exploring diverse aspects of primitive reflexes and revealing their clinical implication in the high-risk newborns that are unique and different to normal healthy newborns. Primitive reflex; High risk infants; Korean; Moro reflex; Sucking reflex; Babinski reflex; The Anderson Behavioral State Scale; Infant Coma Scale.

  3. Reflex anuria after renal tumor embolization.

    Science.gov (United States)

    Kervancioglu, Selim; Sirikci, Akif; Erbagci, Ahmet

    2007-01-01

    We report a case of reflex anuria after transarterial embolization of a renal tumor. Anuria developed immediately after embolization and resolved 74 hr following the procedure. We postulate that reflux anuria in our case was related to mechanoreceptors, chemoreceptors, or both, as these are stimulated by the occluded blood vessels, ischemia, and edema of the normal renal tissue of an embolized kidney.

  4. Madonna as a symbol of reflexive modernisation

    NARCIS (Netherlands)

    van den Berg, M.; ter Hoeven, C.L.

    2013-01-01

    The communication of social and cultural tensions embodied in the symbol Madonna explain the unparalleled public and scientific fascination for this cultural phenomenon. These tensions can be seen as communications of reflexive modernisation, in which modernisation has produced its own counterforce.

  5. Reflex epilepsy: triggers and management strategies

    Directory of Open Access Journals (Sweden)

    Okudan ZV

    2018-01-01

    Full Text Available Zeynep Vildan Okudan,1 Çiğdem Özkara2 1Department of Neurology, Bakirkoy Dr Sadi Konuk Education and Research Hospital, 2Department of Neurology and Clinical Neurophysiology, Cerrahpasa Faculty of Medicine, University of Istanbul, Istanbul, Turkey Abstract: Reflex epilepsies (REs are identified as epileptic seizures that are consistently induced by identifiable and objective-specific triggers, which may be an afferent stimulus or by the patient’s own activity. RE may have different subtypes depending on the stimulus characteristic. There are significant clinical and electrophysiologic differences between different RE types. Visual stimuli-sensitive or photosensitive epilepsies constitute a large proportion of the RE and are mainly related to genetic causes. Reflex epilepsies may present with focal or generalized seizures due to specific triggers, and sometimes seizures may occur spontaneously. The stimuli can be external (light flashes, hot water, internal (emotion, thinking, or both and should be distinguished from triggering precipitants, which most epileptic patients could report such as emotional stress, sleep deprivation, alcohol, and menstrual cycle. Different genetic and acquired factors may play a role in etiology of RE. This review will provide a current overview of the triggering factors and management of reflex seizures. Keywords: seizure, reflex epilepsy, photosensitivity, hot water, reading, thinking

  6. Blink reflex in type 2 diabetes mellitus.

    Science.gov (United States)

    Elkholy, Saly H; Hosny, Hanan M; Shalaby, Nevein M; El-Hadidy, Reem A; Abd El-Rahim, Noha T; Mohamed, Manal M

    2014-12-01

    An evaluation of the extent of damage of the central nervous system in diabetes mellitus is of high value in current research. Electrophysiological abnormalities are frequently present in asymptomatic patients with diabetes mellitus. Diabetic cranial neuropathy is one of the complications of the disease. Blink reflex is used to diagnose subclinical cranial neuropathy. The objective is to test the utility of blink reflex in detecting subclinical cranial nerve involvement in patients with type 2 diabetes mellitus. Forty patients with type 2 diabetes mellitus, aged from 30 to 60 years examined clinically and neurologically. Blink reflex and nerve conduction studies for the upper and lower limbs were performed and compared with 20 matched normal controls. Diabetic patients with peripheral neuropathy showed significant prolonged distal latency and reduced amplitudes of the R2C response compared with the control, patients without peripheral neuropathy showed insignificant changes. Alteration of R2 correlated with the type of treatment and the duration of the disease. In patients without peripheral neuropathy, ulnar sensory distal latencies showed significant positive correlation with R2I latency, whereas its Conduction Velocity (CV) showed significant positive correlation with R2C amplitudes and negative correlation with R2C latency. R2C is the most sensitive parameter in the blink reflex, which can help in the diagnosis of subclinical diabetic cranial neuropathy.

  7. Biological Motion Cues Trigger Reflexive Attentional Orienting

    Science.gov (United States)

    Shi, Jinfu; Weng, Xuchu; He, Sheng; Jiang, Yi

    2010-01-01

    The human visual system is extremely sensitive to biological signals around us. In the current study, we demonstrate that biological motion walking direction can induce robust reflexive attentional orienting. Following a brief presentation of a central point-light walker walking towards either the left or right direction, observers' performance…

  8. Reflexivity on Banach Spaces of Analytic Functions

    Directory of Open Access Journals (Sweden)

    B. Yousefi and J. Doroodgar

    2008-03-01

    Full Text Available . Let X be a Banach space of functions analytic on a plane domain Ω such that for every λ in Ω the functional of evaluation at λ is bounded. Assume further that X contains the constants and admits multiplication by the independent variable z, Mz, as a bounded operator. We give sufficient conditions for Mz to be reflexive.

  9. Scrutinising the reflexive ethnography of Urban Outcasts

    DEFF Research Database (Denmark)

    Larsen, Troels Schultz

    2016-01-01

    The core of Bourdieu and Wacquant’s ‘epistemic reflexivity’ demands an embodied reflexivity which takes up the point of view of the practice and the social problems under study via a reflection and reconstruction of the point of view of the ethnographer as an agent embedded in a scientific practi...

  10. Control of reflexive saccades following hemispherectomy.

    Science.gov (United States)

    Reuter-Lorenz, Patricia A; Herter, Troy M; Guitton, Daniel

    2011-06-01

    Individuals who have undergone hemispherectomy for treatment of intractable epilepsy offer a rare and valuable opportunity to examine the ability of a single cortical hemisphere to control oculomotor performance. We used peripheral auditory events to trigger saccades, thereby circumventing dense postsurgical hemianopia. In an antisaccade task, patients generated numerous unintended short-latency saccades toward contralesional auditory events, indicating pronounced limitations in the ability of a single hemicortex to exert normal inhibitory control over ipsilateral (i.e., contralesional) reflexive saccade generation. Despite reflexive errors, patients retained an ability to generate correct antisaccades in both directions. The prosaccade task revealed numerous contralesional express saccades, a robust contralesional gap effect, but the absence of both effects for ipsilesional saccades. These results indicate limits to the saccadic control capabilities following hemispherectomy: A single hemicortex can mediate antisaccades in both directions, but plasticity does not extend fully to the bilateral inhibition of reflexive saccades. We posit that these effects are due to altered control dynamics that reduce the responsivity of the superior colliculus on the intact side and facilitate the release of an auditory-evoked ocular grasp reflex into the blind hemifield that the intact hemicortex has difficulty suppressing.

  11. Optimizing the sensitivity of the head thrust test for identifying vestibular hypofunction.

    Science.gov (United States)

    Schubert, Michael C; Tusa, Ronald J; Grine, Lawrence E; Herdman, Susan J

    2004-02-01

    The head thrust test (HTT) is used to assess the vestibulo-ocular reflex. Sensitivity and specificity for diagnosing unilateral vestibular hypofunction (UVH) in patients following vestibular ablation is excellent (100%), although sensitivity is lower (35%-39%) for patients with nonsurgically induced UVH. The variability of the test results may be from moving the subject's head outside the plane of the lateral semicircular canals as well as using a head thrust of predictable timing and direction. The purpose of this study was to examine sensitivity and specificity of the horizontal HTT in identifying patients with UVH and bilateral vestibular hypofunction (BVH) when the head was flexed 30 degrees in attempt to induce acceleration primarily in the lateral semicircular canal and the head was moved unpredictably. The medical records of 176 people with and without vestibular dysfunction (n=79 with UVH, n=32 with BVH, and n=65 with nonvestibular dizziness) were studied. Data were retrospectively tabulated from a de-identified database (ie, with health information stripped of all identifiers). Sensitivity of the HTT for identifying vestibular hypofunction was 71% for UVH and 84% for BVH. Specificity was 82%. Ensuring the head is pitched 30 degrees down and thrust with an unpredictable timing and direction appears to improve sensitivity of the HTT.

  12. Saccade and vestibular ocular motor adaptation.

    Science.gov (United States)

    Schubert, Michael C; Zee, David S

    2010-01-01

    This paper focuses on motor learning within the saccadic and vestibulo-ocular reflex (VOR) oculomotor systems, vital for our understanding how the brain keeps these subsystems calibrated in the presence of disease, trauma, and the changes that invariably accompany normal development and aging. We will concentrate on new information related to multiple time scales of saccade motor learning, adaptation of the VOR during high-velocity impulses, and the role of saccades in VOR adaptation. The role of the cerebellum in both systems is considered. Review of data involving saccade and VOR motor learning. Data supports learning within the saccadic and VOR oculomotor systems is influenced by 1). Multiple time scales, with different rates of both learning and forgetting (seconds, minutes, hours, days, and months). In the case of forgetting, relearning on a similar task may be faster. 2). Pattern of training, learning and forgetting are not similarly achieved. Different contexts require different motor behaviors and rest periods between training sessions can be important for memory consolidation. The central nervous system has the difficult task of determining where blame resides when motor performance is impaired (the credit assignment problem). Saccade and VOR motor learning takes place at multiple levels within the nervous system, from alterations in ion channel and membrane properties on single neurons, to more complex changes in neural circuit behavior and higher-level cognitive processes including prediction.

  13. Reliability of the clinical and electromyographic examination of tendon reflexes

    NARCIS (Netherlands)

    Stam, J.; van Crevel, H.

    1990-01-01

    The reliability of clinical examination of the tendon reflexes was examined by studying inter-observer agreement. Twenty patients were examined by three neurologists. The briskness of the tendon reflexes in arms and legs was scored on a nine-point scale. In 28% of the 160 examined reflexes the

  14. Modulation of spinal reflexes by aversive and sexually appetitive stimuli

    NARCIS (Netherlands)

    Both, Stephanie; Everaerd, Walter; Laan, Ellen

    2003-01-01

    In this study, modulation of spinal tendinous (T) reflexes by sexual stimulation was investigated. T reflexes are augmented in states of appetitive and defensive action and modified by differences in arousal intensity. Reflexes were expected to be facilitated by both pleasant (sexual) and unpleasant

  15. Consistency of the Babinski reflex and its variants.

    Science.gov (United States)

    Singerman, J; Lee, L

    2008-09-01

    The Babinski Reflex, first described in 1896, is still an integral part of the neurological examination. Many have studied the consistency of this reflex, but none have compared the inter- and intra-observer consistency of the Babinski reflex and its variants. Thirty-four subjects were examined by six neurologists. The Babinski, Gordon, Chaddock, and Oppenheim reflexes were tested, and each neurologist concluded if the plantar response was flexor or extensor. Six subjects were re-tested 1 week later to determine intra-observer consistency. The Babinski reflex had the highest interobserver consistency with a kappa value of 0.5491. The Chaddock, Oppenheim, and Gordon reflexes had kappa values of 0.4065, 0.3739, and 0.3515, respectively. For intra-observer consistency, Gordon was the most consistent with a kappa value of 0.6731. When reflexes were combined in pairs, the Babinski and Chaddock reflexes together were the most reliable. The Babinski reflex was shown to be the most consistent between examiners. The Gordon reflex had the highest intra-observer consistency; however, the small sample size should limit conclusions drawn from this calculation. Clinicians often utilize more than one reflex to examine the plantar response; the combination of the Babinski and Chaddock reflexes was the most reliable.

  16. Tendon reflex asymmetry by voluntary mental effort in healthy subjects

    NARCIS (Netherlands)

    Stam, J.; Speelman, H. D.; van Crevel, H.

    1989-01-01

    The effect of voluntary mental influences on the tendon reflexes was examined in healthy subjects. The patellar reflexes were evoked by a method comparable with the clinical examination, and the reflexes were recorded by surface electrodes. Eighteen subjects were instructed to increase and then

  17. New Molecular Knowledge Towards the Trigemino-Cardiac Reflex as a Cerebral Oxygen-Conserving Reflex

    Directory of Open Access Journals (Sweden)

    N. Sandu

    2010-01-01

    Full Text Available The trigemino-cardiac reflex (TCR represents the most powerful of the autonomous reflexes and is a subphenomenon in the group of the so-called “oxygen-conserving reflexes”. Within seconds after the initiation of such a reflex, there is a powerful and differentiated activation of the sympathetic system with subsequent elevation in regional cerebral blood flow (CBF, with no changes in the cerebral metabolic rate of oxygen (CMRO2 or in the cerebral metabolic rate of glucose (CMRglc. Such an increase in regional CBF without a change of CMRO2 or CMRglc provides the brain with oxygen rapidly and efficiently. Features of the reflex have been discovered during skull base surgery, mediating reflex protection projects via currently undefined pathways from the rostral ventrolateral medulla oblongata to the upper brainstem and/or thalamus, which finally engage a small population of neurons in the cortex. This cortical center appears to be dedicated to transduce a neuronal signal reflexively into cerebral vasodilatation and synchronization of electrocortical activity; a fact that seems to be unique among autonomous reflexes. Sympathetic excitation is mediated by cortical-spinal projection to spinal preganglionic sympathetic neurons, whereas bradycardia is mediated via projections to cardiovagal motor medullary neurons. The integrated reflex response serves to redistribute blood from viscera to the brain in response to a challenge to cerebral metabolism, but seems also to initiate a preconditioning mechanism. Previous studies showed a great variability in the human TCR response, in special to external stimuli and individual factors. The TCR gives, therefore, not only new insights into novel therapeutic options for a range of disorders characterized by neuronal death, but also into the cortical and molecular organization of the brain.

  18. [Developing team reflexivity as a learning and working tool for medical teams].

    Science.gov (United States)

    Riskin, Arieh; Bamberger, Peter

    2014-01-01

    Team reflexivity is a collective activity in which team members review their previous work, and develop ideas on how to modify their work behavior in order to achieve better future results. It is an important learning tool and a key factor in explaining the varying effectiveness of teams. Team reflexivity encompasses both self-awareness and agency, and includes three main activities: reflection, planning, and adaptation. The model of briefing-debriefing cycles promotes team reflexivity. Its key elements include: Pre-action briefing--setting objectives, roles, and strategies the mission, as well as proposing adaptations based on what was previously learnt from similar procedures; Post-action debriefing--reflecting on the procedure performed and reviewing the extent to which objectives were met, and what can be learnt for future tasks. Given the widespread attention to team-based work systems and organizational learning, efforts should be made toward ntroducing team reflexivity in health administration systems. Implementation could be difficult because most teams in hospitals are short-lived action teams formed for a particular event, with limited time and opportunity to consciously reflect upon their actions. But it is precisely in these contexts that reflexive processes have the most to offer instead of the natural impulsive collective logics. Team reflexivity suggests a potential solution to the major problems of iatorgenesis--avoidable medical errors, as it forces all team members to participate in a reflexive process together. Briefing-debriefing technology was studied mainly in surgical teams and was shown to enhance team-based learning and to improve quality-related outcomes and safety.

  19. Electrical stimulation of sacral dermatomes can suppress aberrant urethral reflexes in felines with chronic spinal cord injury.

    Science.gov (United States)

    McCoin, Jaime L; Bhadra, Narendra; Gustafson, Kenneth J

    2013-01-01

    Uncoordinated reflex contractions of the external urethral sphincter (EUS) are a major component of voiding dysfunction after neurologic injury. Patterned stimulation of sacral afferent pathways can reduce abnormal EUS reflexes after acute spinal cord injury (SCI); however, effectiveness following chronic SCI is unknown. Four adult male cats were implanted with bilateral extradural sacral root electrodes to allow bladder activation and underwent subsequent spinal transection (T10-12). Nine weeks after SCI urethral and bladder pressures were recorded with and without sacral afferent stimulation. Surface electrodes were applied to sacral and lumbar dermatomes and stimulus amplitude set below the muscle fasciculation threshold. The stimulation pattern was varied by on/off times of fixed frequency at each location. Reflexive EUS contractions were observed in all animals after chronic SCI. Patterned sacral dermatome stimulation reduced EUS reflex rate and amplitude in two of four cats. Suppression was dependent on both the stimulus location and pattern. Sacral locations and a stimulation pattern of (0.75 sec on, 0.25 sec off, 20 Hz) were effective in both responder animals. Patterned sacral dermatome stimulation can reduce abnormal urethral reflexes following chronic SCI. Reflex suppression is dependent on both the stimulation location and stimulus pattern. Reduction of reflexive EUS activity after chronic SCI with this non-destructive and non-invasive approach may provide an advance for the treatment of detrusor-sphincter-dyssynergia. Copyright © 2012 Wiley Periodicals, Inc.

  20. Interaction between the long-latency stretch reflex and voluntary electromyographic activity prior to a rapid voluntary motor reaction.

    Science.gov (United States)

    Day, B L; Rothwell, J C; Marsden, C D

    1983-06-27

    The size of the long-latency component of the stretch reflex has been examined in the time interval between a signal to move and the required rapid voluntary contraction of triceps and flexor pollicis longus in 8 normal subjects. Bilateral movements of the elbow and thumb were made following an auditory signal. In 50% of the trials a torque pulse was applied unilaterally in order to elicit a stretch reflex response in one arm. The voluntary response in the contralateral arm was uncorrupted by a stretch reflex response, so was used as an indicator of voluntary reaction time. Control experiments, using an electrical stimulus to the fingers rather than muscle stretch, verified that both arms reacted almost simultaneously to the auditory cue, even when the reaction time was shortened by the presence of a unilateral electrical stimulus. Similarly, an interposed muscle stretch stimulus considerably reduced the reaction time to the audio signal. Because of this, the start of the voluntary EMG response frequently 'over-lapped' the end of the long-latency stretch reflex. Failure to take this shortening of voluntary reaction time into consideration can lead to the erroneous conclusion that reflex gain is increased prior to a rapid movement. If the 'overlap' of EMG responses is accounted for, very little change in the size of the long-latency stretch reflex is evident prior to activation of the muscles responsible for the movement of either the elbow or the thumb.

  1. Reading from a Head-Fixed Display during Walking: Adverse Effects of Gaze Stabilization Mechanisms.

    Directory of Open Access Journals (Sweden)

    Olivier Borg

    Full Text Available Reading performance during standing and walking was assessed for information presented on earth-fixed and head-fixed displays by determining the minimal duration during which a numerical time stimulus needed to be presented for 50% correct naming answers. Reading from the earth-fixed display was comparable during standing and walking, with optimal performance being attained for visual character sizes in the range of 0.2° to 1°. Reading from the head-fixed display was impaired for small (0.2-0.3° and large (5° visual character sizes, especially during walking. Analysis of head and eye movements demonstrated that retinal slip was larger during walking than during standing, but remained within the functional acuity range when reading from the earth-fixed display. The detrimental effects on performance of reading from the head-fixed display during walking could be attributed to loss of acuity resulting from large retinal slip. Because walking activated the angular vestibulo-ocular reflex, the resulting compensatory eye movements acted to stabilize gaze on the information presented on the earth-fixed display but destabilized gaze from the information presented on the head-fixed display. We conclude that the gaze stabilization mechanisms that normally allow visual performance to be maintained during physical activity adversely affect reading performance when the information is presented on a display attached to the head.

  2. Recovery of dynamic visual acuity in bilateral vestibular hypofunction.

    Science.gov (United States)

    Herdman, Susan J; Hall, Courtney D; Schubert, Michael C; Das, Vallabh E; Tusa, Ronald J

    2007-04-01

    To determine the effect of vestibular exercises on the recovery of visual acuity during head movement in patients with bilateral vestibular hypofunction (BVH). Prospective, randomized, double-blinded study. Outpatient clinic, academic setting. Thirteen patients with BVH, aged 47 to 73 years. One group (8 patients) performed vestibular exercises designed to enhance remaining vestibular function, and the other (5 patients) performed placebo exercises. Measurements of dynamic visual acuity (DVA) during predictable head movements using a computerized test; measurement of intensity of oscillopsia using a visual analog scale. As a group, patients who performed vestibular exercises showed a significant improvement in DVA (P = .001), whereas those performing placebo exercises did not (P = .07). Only type of exercise (ie, vestibular vs placebo) was significantly correlated with change in DVA. Other factors examined, including age, time from onset, initial DVA, and complaints of oscillopsia and disequilibrium, were not significantly correlated with change in DVA. Change in oscillopsia did not correlate with change in DVA. Use of vestibular exercises is the main factor involved in recovery of DVA in patients with BVH. We theorize that exercises may foster the use of centrally programmed eye movements that could substitute for the vestibulo-ocular reflex. clinicaltrials.gov Identifier: NCT00411216.

  3. JÁNOS SZENTÁGOTHAI. 31 October 1912 - 8 September 1994: Elected ForMemRs 20 April 1978.

    Science.gov (United States)

    Gulyás, Balázs; Somogyi, Peter

    2013-12-01

    János Szentágothai was an eminent, creative and renowned neuroscientist, who made pioneering and seminal discoveries contributing to our current understanding of brain functions. His vision of the brain as a network of specific populations of nerve cells, each engaging in selective operations and self-organizing into modules, has provided the framework and stimulus for generations of neuroscientists. His irrepressible curiosity and enthusiasm for the beauty in the organization of the brain never faded. He had a towering intellect and was a great humanist. Szentágothai was born in Budapest, Hungary, in 1912 and died in his native city in 1994. He was educated and worked in Hungary. During the six decades of his scientific activity, he made remarkably original and lasting contributions to the neurosciences, including the exploration of basic architectural features of many brain areas, the functional-anatomical bases of elementary brain operations such as reflex arcs, the vestibulo-ocular system, the brain control of hormonal regulation, general organizational principles of the neuraxis, the organization of the cerebellum and the modular organization of the neocortex. He left for posterity not only his discoveries, which have stood the test of time, but also a vigorous school of pupils as well as a large number of friends and admirers. Thanks to him neuroscience is one of the strongest scientific fields in Hungary today.

  4. Replacing semicircular canal function with a vestibular implant.

    Science.gov (United States)

    Merfeld, Daniel M; Lewis, Richard F

    2012-10-01

    To summarize the recent progress in the development of vestibular implants. The review is timely because of the recent advances in the field and because MED-EL has recently announced that they are developing a vestibular implant for clinical applications. The handicap experienced by patients suffering from bilateral vestibulopathy has a strong negative impact on physical and social functioning that appears to justify a surgical intervention. Two different surgical approaches to insert electrodes to stimulate ampullary neurons have been shown to be viable. The three-dimensional vestibulo-ocular reflex in rhesus monkeys produced with a three-dimensional vestibular implant showed gains that were relatively normal during acute stimulation. Rotation cues provided by an implant interact with otolith cues in a qualitatively normal manner. The brain appears to adapt plastically to the cues provided via artificial electrical stimulation. Research to date includes just a few human studies, but available data from both humans and animals support the technological and physiological feasibility of vestibular implants. Although vestibular implant users should not expect normal vestibular function - any more than cochlear implant users should expect normal hearing - data suggest that significant functional improvements are possible.

  5. Significant vestibular system impairment is common in a cohort of elderly patients referred for assessment of falls risk.

    Science.gov (United States)

    Jacobson, Gary P; McCaslin, Devin L; Grantham, Sarah L; Piker, Erin G

    2008-01-01

    Falls in elderly patients are associated with morbidity, mortality, and cost to the healthcare system. The development of falls risk assessment programs have represented a method of responding to what is known about injurious falls. The multidimensional assessments involve the comparison against normative data of a patient's performance on metrics known to influence the likelihood of future falls. The factors assessed usually include falls and medication history, measures of mentation, depression, orthostatic hypotension, simple or choice reaction time, gait stability, postural stability, and the integrity of the patient's vision, somesthetic, and vestibular senses. This investigation was conducted to measure the proportion of patients referred for falls risk assessment who have evidence of vestibular system impairment. Qualitative, retrospective review of data collected from 2003 to 2007. The cohort was 185 consecutive patients referred for multidimensional assessments of falls risk. Patients underwent quantitative assessments of peripheral and central vestibular system function consisting of electro- or videonystagmography (i.e., ENG/VNG), and sinusoidal harmonic acceleration testing. Results of these tests were compared to normative data. We found that 73% of the sample who underwent vestibular system assessment had quantitative evidence of either peripheral or central vestibular system impairment. Our results suggest that quantitative assessments of the vestibulo-ocular reflex should be conducted on patients who are evaluated for falls risk. These examinations should include at least caloric testing and, where available, rotational testing.

  6. A versatile stereoscopic visual display system for vestibular and oculomotor research.

    Science.gov (United States)

    Kramer, P D; Roberts, D C; Shelhamer, M; Zee, D S

    1998-01-01

    Testing of the vestibular system requires a vestibular stimulus (motion) and/or a visual stimulus. We have developed a versatile, low cost, stereoscopic visual display system, using "virtual reality" (VR) technology. The display system can produce images for each eye that correspond to targets at any virtual distance relative to the subject, and so require the appropriate ocular vergence. We elicited smooth pursuit, "stare" optokinetic nystagmus (OKN) and after-nystagmus (OKAN), vergence for targets at various distances, and short-term adaptation of the vestibulo-ocular reflex (VOR), using both conventional methods and the stereoscopic display. Pursuit, OKN, and OKAN were comparable with both methods. When used with a vestibular stimulus, VR induced appropriate adaptive changes of the phase and gain of the angular VOR. In addition, using the VR display system and a human linear acceleration sled, we adapted the phase of the linear VOR. The VR-based stimulus system not only offers an alternative to more cumbersome means of stimulating the visual system in vestibular experiments, it also can produce visual stimuli that would otherwise be impractical or impossible. Our techniques provide images without the latencies encountered in most VR systems. Its inherent versatility allows it to be useful in several different types of experiments, and because it is software driven it can be quickly adapted to provide a new stimulus. These two factors allow VR to provide considerable savings in time and money, as well as flexibility in developing experimental paradigms.

  7. The Interrater Reliability of Subjective Assessments of the Babinski Reflex.

    Science.gov (United States)

    Dafkin, Chloe; Green, Andrew; Kerr, Samantha; Veliotes, Demetri; Olivier, Benita; McKinon, Warrick

    2016-01-01

    The Babinski reflex is a clinical diagnostic tool; however, the interrater reliability of this tool is currently greatly contested. A comparison between rater groups with objective measurements of the Babinski reflex was therefore conducted. Fifteen recorded Babinski reflexes were assessed by 12 neurologists and 12 medical students as being either pathological or nonpathological. Kinematic and electromyographic variables were collected and used to assess which aspects of the Babinski reflex predict classification. Substantial interrater agreement within the neurologist and student groups (κ = .72 and .67, respectively) was shown; however, there were some differing aspects between what neurologists and students used to assess the reflex as determined by objective kinematic measurements.

  8. Assessing TMS-induced D- and I-waves with spinal H-reflexes.

    Science.gov (United States)

    Niemann, Niclas; Wiegel, Patrick; Kurz, Alexander; Rothwell, John C; Leukel, Christian

    2017-11-15

    Transcranial magnetic stimulation (TMS) of motor cortex produces a series of descending volleys known as D- (direct) and I- (indirect) waves. In the present study, we questioned whether spinal H-reflexes can be used to dissect D-waves, early and late I-waves from TMS. We therefore probed H-reflex facilitation at arrival times of D- and I-waves at the spinal level and thereby changed TMS parameters that have previously been shown to have selective effects on evoked D- and different I-waves. We changed TMS intensity and current direction, and applied a double-pulse paradigm known as short-interval intracortical inhibition (SICI). Experiments were conducted in flexor carpi radialis (FCR) in the arm and soleus (SOL) in the leg. There were two major findings: I) In FCR, H-reflex facilitation showed characteristic modulations with altered TMS-parameters that correspond to the changes of evoked D- and I-waves. II) H-reflexes in SOL did not, possibly because of increased interference from other spinal circuits. Therefore, the most significant outcome of this study is that in FCR, H-reflexes combined with TMS seem to be a useful technique to dissect TMS-induced D- and I-waves.

  9. Posturography does not test vestibulospinal function.

    Science.gov (United States)

    Evans, M K; Krebs, D E

    1999-02-01

    The clinical usefulness of posturography is unknown, despite its costing more than +500 per test in some areas of the United States, including Boston. We cross-sectionally and prospectively studied blinded vestibulo-ocular and vestibulospinal tests from 29 stable patients with chronic vestibular hypofunction; 22 patients were affected bilaterally (BVH), and 7 were affected unilaterally (UVH). Vestibulo-ocular function was assessed by electronystagmographic caloric stimulation and sinusoidal vertical axis rotation gains at 0.05 Hz. Vestibulospinal function was assessed by moving-platform and visualsurround posturography sensory organization tests (SOTs), paced and free gait in a gait laboratory, and clinical tests of timed gait and standing. Posturography SOT moving-platform tests 4 through 6, designed to assess vestibular function, correlated significantly (r or = 0.01) with vestibulo-ocular tests in 5 of 6 comparisons among BVH patients. Posturography SOT results, however, correlated poorly with other vestibulospinal measures: correlations were statistically significant for only 7 of 18 comparisons with clinical balance and gait function (r or = 0.01) and with 2 of 12 comparisons for gait laboratory dynamic stability measures (r or = 0.01) among the BVH patients. When both the platform and visual surround moved (SOT 6), however, correlations were statistically significant with static standing clinical measures (r = 0.51 to 0.69, P BVH posturography SOT scores relate at best modestly with accepted measure of vestibulo-ocular function, less well with clinical measures of balance control, and poorly with dynamic gait-performance measures. We conclude that posturography SOT does not assess vestibulospinal function.

  10. Reflexive cartography a new perspective in mapping

    CERN Document Server

    Casti, Emanuela

    2015-01-01

    Reflexive Cartography addresses the adaptation of cartography, including its digital forms (GIS, WebGIS, PPGIS), to the changing needs of society, and outlines the experimental context aimed at mapping a topological space. Using rigorous scientific analysis based on statement consistency, relevance of the proposals, and model accessibility, it charts the transition from topographical maps created by state agencies to open mapping produced by citizens. Adopting semiotic theory to uncover the complex communicative mechanisms of maps and to investigate their ability to produce their own messages and new perspectives, Reflexive Cartography outlines a shift in our way of conceptualizing maps: from a plastic metaphor of reality, as they are generally considered, to solid tools that play the role of agents, assisting citizens as they think and plan their own living place and make sense of the current world. Applies a range of technologies to theoretical perspectives on mapping to innovatively map the world's geogr...

  11. The Reflexive Principle of Sociological Theorization

    Directory of Open Access Journals (Sweden)

    R T Ubaidullayeva

    2013-12-01

    Full Text Available The article attempts to describe the reflexive principle in theory-making, which integrates the basic modern methodological paradigms and lays the foundation for the development of sociology. On the basis of the theoretical ideas of P. Bourdieu, A. Giddens and P. Ricoeur the author defines the concept of social reflexion and reveals its peculiarities in sociology as compared to reflexion in philosophy. According to the author, the fulfillment of reflexive functions in sociology is connected with the task of analyzing the complex structure of the polysemantic object, considering the specific quality of the subjects and their various trends of development. The presence of the poles — objectivity-subjectivity, rationality-irrationality, consciousness-unconsciousness etc, requires a reproduction of the dichotomies engendering them in social life and development of cognitive methods for their study in sociology.

  12. GABAergic processes mediate thermal prolongation of the laryngeal reflex apnea in decerebrate piglets.

    Science.gov (United States)

    Böhm, Ines; Xia, Luxi; Leiter, J C; Bartlett, Donald

    2007-05-14

    We tested the hypotheses that elevated body temperature would prolong reflex apnea following electrical stimulation of the superior laryngeal nerve (SLN) in decerebrate neonatal piglets and that thermal prolongation of reflex apnea after stimulation of the SLN depended on GABAergic mechanisms. These studies were conducted in 13 decerebrate piglets (age 3-15 days). The SLN was stimulated at approximately 1.5 times the threshold stimulus level for 10 s starting at the beginning of inspiration. We measured the duration of the apnea and respiratory disruption that followed SLN stimulation. Elevating body temperature prolonged the duration of the apnea and respiratory disruption that followed SLN stimulation, and treatment with antagonists of gama-aminobutyric acid A-type (GABAA) receptors reversed the thermal prolongation of reflex apnea and the period of respiratory disruption even though body temperature remained elevated. We conclude that elevated body temperature enhances or amplifies GABAergic mechanisms that prolong the respiratory inhibition following electrical stimulation of the SLN.

  13. Biobehavioural analysis of the vestibular system and posture control in patients with cervicogenic dizziness. A cross-sectional study.

    Science.gov (United States)

    Grande-Alonso, M; Moral Saiz, B; Mínguez Zuazo, A; Lerma Lara, S; La Touche, R

    2016-07-21

    Cervicogenic dizziness is a musculoskeletal disorder mainly characterised by dizziness and disequilibrium associated with neck pain. The pathophysiology is unclear and the neurophysiological basis remains to be ascertained. The aim of this study is to compare the vestibulo-ocular reflex and postural control between patients with cervicogenic dizziness and asymptomatic subjects, and to assess the association between debilitating dizziness and other psychosocial variables. A total of 20 patients and 22 asymptomatic subjects were selected. Vestibulo-ocular reflex was assessed by performing the head impulse test. Computerised dynamic posturography was used to evaluate the postural control by means of the sensory organisation test. In addition, subjects self-reported their degree of disability due to dizziness, cervical disability, kinesiophobia, and state of anxiety and depression. There were no differences in the vestibulo-ocular reflex (P>.05). However, we found differences with a medium-to-large effect size (d>0.60) in variables related to proprioception and visual information integration; the former variable set was related to disability due to dizziness. Disability due to dizziness presents strong-to-moderate associations with cervical disability, kinesiophobia, and anxiety. Our data rule out changes in the vestibular system in cervicogenic dizziness, but they do point to proprioceptive impairment. According to our results, the association between dizziness-related disability and other psychosocial factors in cervicogenic dizziness is very relevant for clinical medicine and for future research projects. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. The Cushing Reflex: Oliguria as a Reflection of an Elevated Intracranial Pressure

    Directory of Open Access Journals (Sweden)

    K. Leyssens

    2017-01-01

    Full Text Available Oliguria is one of the clinical hallmarks of renal failure. The broad differential diagnosis is well known, but a rare cause of oliguria is intracranial hypertension (ICH. The actual knowledge to explain this relationship is scarce. Almost all literature is about animals where authors describe the Cushing reflex in response to ICH. We hypothesize that the Cushing reflex is translated towards the sympathetic nervous system and renin-angiotensin-aldosterone system with a subsequent reduction in medullary blood flow and oliguria. Recently, we were confronted with a patient who had complicated pituitary surgery and displayed multiple times an oliguria while he developed ICH.

  15. The effect of distraction strategies on pain perception and the nociceptive flexor reflex (RIII reflex).

    Science.gov (United States)

    Ruscheweyh, Ruth; Kreusch, Annette; Albers, Christoph; Sommer, Jens; Marziniak, Martin

    2011-11-01

    Distraction from pain reduces pain perception, and imaging studies have suggested that this may at least partially be mediated by activation of descending pain inhibitory systems. Here, we used the nociceptive flexor reflex (RIII reflex) to directly quantify the effects of different distraction strategies on basal spinal nociception and its temporal summation. Twenty-seven healthy subjects participated in 3 distraction tasks (mental imagery, listening to preferred music, spatial discrimination of brush stimuli) and, in a fourth task, concentrated on the painful stimulus. Results show that all 3 distraction tasks reduced pain perception, but only the brush task also reduced the RIII reflex. The concentration-on-pain task increased both pain perception and the RIII reflex. The extent of temporal summation of pain perception and the extent of temporal summation of the RIII reflex were not affected by any of the tasks. These results suggest that some, but not all, forms of pain reduction by distraction rely on descending pain inhibition. In addition, pain reduction by distraction seems to preferentially affect mechanisms of basal nociceptive transmission, not of temporal summation. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  16. Esophageal reflexes modulate frontoparietal response in neonates: Novel application of concurrent NIRS and provocative esophageal manometry

    Science.gov (United States)

    Pakiraih, Joanna F.; Hasenstab, Kathryn A.; Dar, Irfaan; Gao, Xiaoyu; Bates, D. Gregory; Kashou, Nasser H.

    2014-01-01

    Central and peripheral neural regulation of swallowing and aerodigestive reflexes is unclear in human neonates. Functional near infrared spectroscopy (NIRS) is a noninvasive method to measure changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbD). Pharyngoesophageal manometry permits evaluation of aerodigestive reflexes. Modalities were combined to investigate feasibility and to test neonatal frontoparietal cortical changes during pharyngoesophageal (visceral) stimulation and/or swallowing. Ten neonates (45.6 ± 3.0 wk postmenstrual age, 4.1 ± 0.5 kg) underwent novel pharyngoesophageal manometry concurrent with NIRS. To examine esophagus-brain interactions, we analyzed cortical hemodynamic response (HDR) latency and durations during aerodigestive provocation and esophageal reflexes. Data are presented as means ± SE or percent. HDR rates were 8.84 times more likely with basal spontaneous deglutition compared with sham stimuli (P = 0.004). Of 182 visceral stimuli, 95% were analyzable for esophageal responses, 38% for HDR, and 36% for both. Of analyzable HDR (n = 70): 1) HbO concentration (μmol/l) baseline 1.5 ± 0.7 vs. 3.7 ± 0.7 poststimulus was significant (P = 0.02), 2) HbD concentration (μmol/l) between baseline 0.1 ± 0.4 vs. poststimulus −0.5 ± 0.4 was not significant (P = 0.73), and 3) hemispheric lateralization was 21% left only, 29% right only, and 50% bilateral. During concurrent esophageal and NIRS responses (n = 66): 1) peristaltic reflexes were present in 74% and HDR in 61% and 2) HDR was 4.75 times more likely with deglutition reflex vs. secondary peristaltic reflex (P = 0.016). Concurrent NIRS with visceral stimulation is feasible in neonates, and frontoparietal cortical activation is recognized. Deglutition contrasting with secondary peristalsis is related to cortical activation, thus implicating higher hierarchical aerodigestive protective functional neural networks. PMID:24789204

  17. The spinal reflex cannot be perceptually separated from voluntary movements

    Science.gov (United States)

    Ghosh, Arko; Haggard, Patrick

    2014-01-01

    Abstract Both voluntary and involuntary movements activate sensors in the muscles, skin, tendon and joints. As limb movement can result from a mixture of spinal reflexes and voluntary motor commands, the cortical centres underlying conscious proprioception might either aggregate or separate the sensory inputs generated by voluntary movements from those generated by involuntary movements such as spinal reflexes. We addressed whether healthy volunteers could perceive the contribution of a spinal reflex during movements that combined both reflexive and voluntary contributions. Volunteers reported the reflexive contribution in leg movements that were partly driven by the knee-jerk reflex induced by a patellar tendon tap and partly by voluntary motor control. In one condition, participants were instructed to kick back in response to a tendon tap. The results were compared to reflexes in a resting baseline condition without voluntary movement. In a further condition, participants were instructed to kick forwards after a tap. Volunteers reported the perceived reflex contribution by repositioning the leg to the perceived maximum displacement to which the reflex moved the leg after each tendon tap. In the resting baseline condition, the reflex was accurately perceived. We found a near-unity slope of linear regressions of perceived on actual reflexive displacement. Both the slope value and the quality of regression fit in individual volunteers were significantly reduced when volunteers were instructed to generate voluntary backward kicks as soon as they detected the tap. In the kick forward condition, kinematic analysis showed continuity of reflex and voluntary movements, but the reflex contribution could be estimated from electromyography (EMG) recording on each trial. Again, participants’ judgements of reflexes showed a poor relation to reflex EMG, in contrast to the baseline condition. In sum, we show that reflexes can be accurately perceived from afferent information

  18. Interlimb reflexes and synaptic plasticity become evident months after human spinal cord injury.

    Science.gov (United States)

    Calancie, Blair; Molano, Maria R; Broton, James G

    2002-05-01

    Persons with long-standing injury to the cervical spinal cord resulting in complete or partial paralysis typically develop a wide spectrum of involuntary movements in muscles receiving innervation caudal to the level of injury. We have previously shown that these movements include brief and discrete contraction of muscles in the hand and forearm in response to innocuous sensory stimulation to the feet and legs, but we have been unable to replicate these interlimb reflexes in able- bodied subjects. Properties of these muscle responses indicate that the synaptic contacts between ascending sensory fibres and motor neurones of the cervical enlargement are more efficacious than normal. If these connections are present at all times, and require the more rostrally-placed spinal cord injury to allow their emergence, one might expect their appearance relatively soon following injury, as has been shown for studies of 'latent' synapses. Conversely, delayed appearance of these interlimb reflexes would suggest either the development of new synaptic connections or a profound strengthening of existing circuits in the cervical spinal cord due to a combination of afferent target loss and motor neurone denervation from motor tracts originating rostral to the injury site. In this study, we used repeated examinations of persons with acute injury to the cervical spinal cord to examine the time post-injury at which interlimb reflexes are first seen. Using tibial nerve stimulation at the knee as a screening test, a total of 24 subjects were found to develop interlimb reflexes following spinal cord injury. Latencies between stimulation and EMG were as brief as 32 ms for muscles of the forearm and 44 ms for muscles in the hand. These minimal delays all but rule out a supraspinal route for these interlimb reflexes. Interlimb reflexes first became evident no sooner than approximately 6 months following injury, and in some individuals were not seen until well over 1 year post-injury. Enhanced

  19. Primitive reflexes distinguish vascular parkinsonism from Parkinson's disease.

    Science.gov (United States)

    Okuda, Bungo; Kawabata, Keita; Tachibana, Hisao; Kamogawa, Kenji; Okamoto, Kensho

    2008-06-01

    Although vascular parkinsonism (VP) occurs frequently in the elderly, its clinical features have not been investigated in detail, particularly in comparison with Parkinson's disease (PD). The goal of this study is to clarify the diagnostic value of pathological reflexes in differentiating between VP and PD. In 132 patients with PD and 55 with VP, pathological reflexes, including snout reflex (SR), palmomental reflex (PMR), corneomandibular reflex (CMR), jaw reflex (JR), Hoffmann reflex (HR), and extensor plantar response (EPR), were evaluated. The percentage of each pathological reflex elicited in two groups (VP:PD) was as follows: SR (78:30), PMR (53:26), CMR (9:6), JR (33:12), HR (29:11), and EPR (25:8). The prevalence of pathological reflexes, except for CMR, was significantly higher in the VP patients than in the PD patients. In particular, SR and PMR were more frequent than upper motor neuron signs in the VP patients. The sensitivity and specificity of either SR or PMR for VP were 84% and 82%. Snout and palmomental reflexes are useful tools in the differentiation between VP and PD.

  20. Polyfunctionality and distribution of reflexive verbs in Latvian

    Directory of Open Access Journals (Sweden)

    Andra Kalnača

    2017-02-01

    Full Text Available The aim of the current paper is to analyze Latvian reflexive verbs from the point of view of their polyfunctionality and distributon.The polysemy of the reflexive verbs is not usually disucussed in the connection with its distribution pattern in the sentence either. This can be partly explianed by the fact that the reflexive verb can have some non-standard language meanings, which following the established practice of the traditional grammars and sometimes even dictionaries,  were not depicted in the language system description either. So the current paper is an attempt to analyze the polyfunctionality of reflexive verbs in connection with their semantic and syntactic functions, without judging the language use from the normative point of view.The classification of Latvian reflexive verbs is based on the relationship between semantic roles and syntactic structure according to the principles devised by Palmer (1994 and Saeed (1997.One and the same reflexive verb may have different lexical meanings with a different distribution for each of the meanings. One and the same verb can belong to different subclasses of the subject and object (or impersonal verbs.Some reflexive verbs have evaluative or aspectual (iterative meanings. The evaluative meanings usually are manifested by a positive or negative assessment of the event (the context can be enhanced by the adverbs good or bad and the consequences while the aspectual meaning is manifested by the intensity of the action, that is – iterativity.The study confirms the assumption that reflexive verbs are independent lexemes as opposed to non-reflexive verb forms. Each reflexive verb has its distinct semantic system and distribution which is different from polysemy of non-reflexive verbs and their distribution. The system of reflexive verbs in Latvian is open where new meanings and even new reflexive verbs arise particularly in colloquial use.

  1. Contribution of M-waves and H-reflexes to contractions evoked by tetanic nerve stimulation in humans.

    Science.gov (United States)

    Klakowicz, Piotr M; Baldwin, Evan R L; Collins, David F

    2006-09-01

    Tetanic neuromuscular stimulation evokes contractions by depolarizing motor axons beneath the stimulating electrodes. However, we have shown that extra torque can develop due to the discharge of spinal neurons recruited by the evoked sensory volley. The present experiments investigated whether extra torque in the ankle plantar- and dorsiflexors was associated with enhanced H-reflexes. The tibial and common peroneal nerves were stimulated using 7-s trains (20 Hz for 2 s, 100 Hz for 2 s, 20 Hz for 3 s). Extra torque was defined as significantly more torque during 20-Hz stimulation after the 100-Hz burst (time2) than before it (time1). In 9 of 11 subjects, extra plantarflexion torque developed during stimulation just above motor threshold. In these nine subjects, torque increased from 8 to 13% MVC (time1 to time2), the soleus H-reflex increased from 13 to 19% Mmax and the M-wave of approximately 2% Mmax did not change significantly. To evoke extra dorsiflexion torque, greater stimulation intensities were required. In 6 of 13 subjects, extra torque developed at intensities that evoked an M-wave of 5-20% Mmax at time1. In these six subjects, torque doubled from 2 to 4% MVC (time1 to time2), whereas tibialis anterior (TA) H-reflexes and M-waves did not change significantly (H-reflex from 0.8 to 2% Mmax; M-wave from 12 to 14% Mmax). In 7 of 13 subjects, extra torque developed at higher stimulation intensities (35-65% Mmax). In these seven subjects, torque increased from 13 to 20% MVC, whereas TA H-reflexes and M-waves were not significantly different (H-reflex from 0.7 to 1% Mmax; M-wave from 49 to 54% Mmax). Thus enhanced H-reflexes contributed to extra plantarflexion, however, other factors generated extra dorsiflexion.

  2. Forbigående tab af balancefunktionen efter cochlear implantation

    DEFF Research Database (Denmark)

    Korsager, Leise Elisabeth Hviid; Schmidt, Jesper Hvass; Faber, Christian

    2017-01-01

    Loss of vestibular function is a common side effect to cochlear implant (CI) surgery. We present a patient who experienced balance problems and showed a reduced vestibulo-ocular reflex (VOR) gain (0.47 ± 0.10) combined with saccades in the horizontal semicircular canals demonstrated by the video...... head impulse test the day after CI surgery. One month after the operation VOR gain was normal (0.95 ± 0.05) and neither balance problems nor saccades occurred. Our findings indicate that vestibular dysfunction after CI surgery can be reversible, and VOR gain can return to normal....

  3. Forbigående tab af balancefunktionen efter cochlear implantation

    DEFF Research Database (Denmark)

    Hviid Korsager, Leise Elisabeth; Schmidt, Jesper; Faber, Christian

    2017-01-01

    Loss of vestibular function is a common side effect to cochlear implant (CI) surgery. We present a patient who experienced balance problems and showed a reduced vestibulo-ocular reflex (VOR) gain (0.47 ± 0.10) combined with saccades in the horizontal semicircular canals demonstrated by the video ...... head impulse test the day after CI surgery. One month after the operation VOR gain was normal (0.95 ± 0.05) and neither balance problems nor saccades occurred. Our findings indicate that vestibular dysfunction after CI surgery can be reversible, and VOR gain can return to normal....

  4. Reliability and comparison of gain values with occurrence of saccades in the EyeSeeCam video head impulse test (vHIT)

    DEFF Research Database (Denmark)

    Hviid Korsager, Leise Elisabeth; Schmidt, Jesper Hvass; Faber, Christian

    2016-01-01

    The vHIT (video head impulse test) investigates the vestibular function in two ways: a VOR (vestibulo-ocular reflex) gain value and a head impulse diagram. From the diagram covert and overt saccades can be detected. Evaluation of the vestibular function based on vHIT depends on both parameters...... implant (CI) surgery. Subjects were tested using the vHIT by two of four different examiners. Two judges interpreted the occurrence of saccades in the diagram. MAIN OUTCOME MEASURES: VOR gain values and the occurrence of saccades in the diagram. Differences in gain values between examiners varied from 0...

  5. A multiparametric analysis of occlusal and periodontal jaw reflex characteristics in adult skeletal mandibular protrusion before and after orthognathic surgery.

    Science.gov (United States)

    Suda, S; MacHida, N; Momose, M; Yamaki, M; Seki, Y; Yoshie, H; Hanada, K; Hara, K

    1999-08-01

    Periodontal jaw reflex, duration of percussion sounds, tooth mobility, and time-moment analysis of occlusal contacts by the T-scan system were recorded in seven pre-orthognathic surgery patients and six post-orthognathic surgery patients over a 2-year period. The results showed that: (i) reflex response to the pressure applied to the upper right central incisor in the lingolabial direction varied, depending on the background jaw-clenching force (BCF) of the same-sided first molar. The BCF level required to elicit excitatory reflexes was only 0 kgf, and inhibitory reflexes were clearly elicited with a BCF of 1 kgf and beyond before orthognathic surgery. After orthognathic surgery BCF levels required to elicit excitatory reflexes were 0-4 kgf, and inhibitory reflexes were elicited with a BCF of 6 kgf and above; (ii) duration of percussion sounds determined via an occlusal sound analyser decreased in both the upper right central incisor and upper right first molar while tooth mobility measured by 'Periotest(R)' increased in the upper right central incisor, but did not change in the same-sided first molar after orthognathic surgery; (iii) the time moments of occlusal contacts were symmetrical toward the midsagittal axis of the occlusal plane after orthognathic surgery. The centre of the anterioposterior occlusal contacts did not differ between pre- and post-orthognathic surgery groups.

  6. An experimental study of artificial murine bladder reflex arc established by abdominal reflex.

    Science.gov (United States)

    Wang, Jin-Wu; Zhao, Yu-Wu; Hou, Chun-Lin; Ni, Wei-Feng; Rui, Bi-Yu; Guo, Shang-Chun; Zheng, Xian-You; Dai, Ke-Rong

    2011-02-01

    The neurogenic bladder dysfunction caused by spinal cord injury is difficult to treat clinically. The aim of this research was to establish an artificial bladder reflex arc in rats through abdominal reflex pathway above the level of spinal cord injury, reinnervate the neurogenic bladder and restore bladder micturition. The outcome was achieved by intradural microanastomosis of the right T13 ventral root to S2 ventral root with autogenous nerve grafting, leaving the right T13 dorsal root intact. Long-term function of the reflex arc was assessed from nerve electrophysiological data and intravesical pressure tests during 8 months postoperation. Horseradish peroxidase (HRP) tracing was performed to observe the effectiveness of the artificial reflex. Single stimulus (3 mA, 0.3 ms pulses, 20 Hz, 5-second duration) on the right T13 dorsal root resulted in evoked action potentials, raised intravesical pressures and bladder smooth muscle, compound action potential recorded from the right vesical plexus before and after the spinal cord transaction injury between L5 and S4 segmental in 12 Sprague-Dawley rats. There were HRP labelled cells in T13 ventral horn on the experimental side and in the intermediolateral nucleus on both sides of the L6-S4 segments after HRP injection. There was no HRP labelled cell in T13 ventral horn on the control side. Using the surviving somatic reflex above the level of spinal cord injury to reconstruct the bladder autonomous reflex arc by intradural microanastomosis of ventral root with a segment of autologous nerve grafting is practical in rats and may have clinical applications for humans.

  7. Control over spinal nociception as quantified by the nociceptive flexor reflex (RIII reflex) can be achieved under feedback of the RIII reflex.

    Science.gov (United States)

    Ruscheweyh, R; Weinges, F; Schiffer, M; Bäumler, M; Feller, M; Krafft, S; Straube, A; Sommer, J; Marziniak, M

    2015-04-01

    Descending pain modulatory systems control transmission of nociceptive information at the spinal level, and their activity can be modified by cognitive and emotional processes. Thus, it may be possible to learn using cognitive-emotional strategies to specifically target descending pathways in order to achieve pain reduction. The present study used visual feedback of the nociceptive flexor reflex (RIII reflex) to train healthy subjects over three sessions to reduce their spinal nociception (RIII reflex size) by self-selected cognitive-emotional strategies. The study included two feedback groups (fixed vs. random stimulation intervals) and a control group without feedback (15 subjects each). While all three groups successfully reduced their RIII reflexes (p nociception under feedback of their RIII reflex size. However, future studies will have to include a sham feedback group to differentiate true learning effects from expectancy effects induced by the feedback procedure. © 2014 European Pain Federation - EFIC®

  8. The comparison of application of two different frequencies of TENS on excitability of Hoffmann reflex

    Directory of Open Access Journals (Sweden)

    Akbari M

    2001-08-01

    Full Text Available The aim of this investigation is to compare the effect of applying two transcutaneous electrical nerve stimulation (TENS current with different frequencies (2 Hz & 100 Hz on Hoffmann reflex recorded from gastrosoleus muscle of healthy people. Forty female subjects between 20 to 30 years of age were participated in this quasi-experimental design. Twenty of them were exposed to the 100 Hz current and the remaining 20 to 2 Hz current on dermatome S1 root. The excitability of the alpha motoneurone was measured by H-reflex amplitude (peak to peak max/2 before and after the application of the TENS current for 30 minutes. The reflex was recorded and at measured before (TO and after the application of TENS at different times (T1, T% and T10 up to 10 minutes. The mean values were compared by multiple paired T test (alpha=0.00825. The results indicate a considerable decrement in Hoffmann reflex amplitude after application of 100 Hz current in comarison with that of before the application. The effect last for 10 minutes after the TENS application, whereas the application of 2 Hz current results in increment of the Hoffmann reflex amplitude. The 5 and 10 minutes interval test dose not show any significance and the results were attenuated befor 5 minutes. As a conclusion high frequency of TENS (100 Hz has an inhibitory effect on excitability of alpha motor neurone reflex lasting for 10 minutes, while low frequency of TENS (2 Hz has an facilatory effect on the same motoneurone with short lasting effect.

  9. High levels of sound pressure: acoustic reflex thresholds and auditory complaints of workers with noise exposure

    Directory of Open Access Journals (Sweden)

    Alexandre Scalli Mathias Duarte

    2015-08-01

    Full Text Available INTRODUCTION: The clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects' auditory complaints.METHODS: This clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests.RESULTS: The workers' age ranged from 18 to 50 years (mean = 39.6, and noise exposure time from one to 38 years (mean = 17.3. We found that 15.1% (55 of the workers had bilateral hearing loss, 38.5% (140 had bilateral tinnitus, 52.8% (192 had abnormal sensitivity to loud sounds, and 47.2% (172 had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3000 and 4000 Hz bilaterally.CONCLUSION: There was no significance relationship between auditory complaints and acoustic reflexes.

  10. A syntactic and lexical approach to French reflexive verbs

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    Corina Petersilka

    2012-01-01

    Full Text Available This Construction grammar approach to French refl exive verbs describes the formal and semantic constraints at work in the different refl exive constructions, points out at their different branches of inheritance and shows cases of fusion with other argument structures. The article suggests a family tree of French reflexive constructions which appear to be derived from different transitive constructions. It also deals with how the reflexive argument structure modifies the semantics of the transitive verb used in reflexive construction.

  11. High-flow oxygen therapy in cluster headache patients has no significant effect on nociception specific blink reflex parameters: a pilot study.

    Science.gov (United States)

    Haane, D Y P; Plaum, A; Koehler, P J; Houben, M P W A

    2016-01-01

    The exact pathophysiology of cluster headache is unclear. We examined the influence of interneurons on the trigemino-facial reflex arch and the effect of oxygen, by using the nociception specific blink reflex parameters. There is no significant effect of oxygen, immediately and over time, on the nociception specific blink reflex parameters in ten male patients during the active phase of cluster headache, outside attacks. Also, there is no significant difference between the symptomatic and asymptomatic side. None of the subjects experienced a cluster headache attack during study participation. We therefore present the collected data as reference values of nociception specific trigeminal stimulation and the effect of oxygen on nociception specific blink reflex parameters. The nociception specific blink reflex seems not a suitable instrument for exploring the pathophysiology of cluster headache.

  12. [Characteristics of the effect of microinjections of scopolamine into the rat neostriatum on the realization of a conditioned food reflex with different degrees of reinforcement].

    Science.gov (United States)

    Tikhonravov, D L; Shapovalova, K B; Diubkacheva, T A

    1995-08-01

    In chronic experiments in 32 male Sprague-Dawley rats on the model of food instrumental reflex (Skinner box) it was shown that the effect of Neostriatal scopolamine microinjections (0.3 mkg) depended on the stage of reflex consolidation. Before the complete reflex consolidation the bilateral microinjections of scopolamine into Nucleus Caudatus produce prolonged inhibition of instrumental reflex. Bilateral Neostriatal microinjections of scopolamine in the same doze had no effect in the case of full consolidation of instrumental reflex. Our results suggest that the cholinergic Neostriatal system is crucially involved in the forming of motor engram of instrumental reaction. In the same time the cholinergic neostriatal system either is not involved in the execution of full consolidate instrumental reactions, or another different forebrain structures patricipate in their realization compensating disturbances of striatal cholinergic function.

  13. The legacy of care as reflexive learning.

    Science.gov (United States)

    García, Marta Rodríguez; Moya, Jose Luis Medina

    2016-06-14

    to analyze whether the tutor's use of reflexive strategies encourages the students to reflect. The goal is to discover what type of strategies can help to achieve this and how tutors and students behave in the practical context. a qualitative and ethnographic focus was adopted. Twenty-seven students and 15 tutors from three health centers participated. The latter had received specific training on reflexive clinical tutoring. The analysis was developed through constant comparisons of the categories. the results demonstrate that the tutors' use of reflexive strategies such as didactic questioning, didactic empathy and pedagogical silence contributes to encourage the students' reflection and significant learning. reflexive practice is key to tutors' training and students' learning. analisar se o uso de estratégias reflexivas por parte da tutora de estágio clínico estimula a reflexão nos estudantes. A intenção é descobrir qual tipo de estratégias podem ajudar a fazê-lo e como as tutoras e os estudantes se comportam no contexto prático. foi adotado um enfoque qualitativo de cunho etnográfico em que participaram 27 estudantes e 15 tutores de três centros de saúde que haviam recebido formação específica sobre tutoria clínica reflexiva. A análise foi realizada por meio de comparações constantes das categorias. os resultados demonstram que o uso de estratégias reflexivas como a interrogação didática, a empatia didática e o silêncio pedagógico por parte das tutoras, contribui para fomentar a reflexão do estudante e sua aprendizagem significativa. a prática reflexiva é a chave para a formação dos tutores e para a aprendizagem dos estudantes. analizar si el uso de estrategias reflexivas por parte de la tutora de prácticas clínicas fomenta la reflexión en los estudiantes. Se trata de conocer qué tipo de estrategias pueden ayudar a hacerlo y cómo se comportan tutoras y estudiantes en el contexto práctico. se ha utilizado un enfoque

  14. Motricidade reflexa na morte cerebral The reflex activity in the brain death

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    Wilson L. Sanvito

    1972-03-01

    Full Text Available O diagnóstico de morte cerebral está baseado em critérios clínicos, eletrencefalográficos e angiográficos. Do ponto de vista clínico deve ser evidenciado o seguinte quadro: coma profundo, midríase paralítica bilateral, ausência de reação a qualquer estímulo externo, apnéia, arreflexia superficial e profunda. Do ponto de vista eletrencefalográfico são necessários dois registros, separados por um intervalo de 24 horas, evidenciando traçados iselétricos. No presente trabalho são estudados 15 pacientes com morte cerebral comprovada do ponto de vista clínico e eletrencefalográfico. Em 8 pacientes havia persistência de atividade reflexa durante a fase de morte cerebral (reflexos profundos e/ou superficiais. Fenômenos de automatismos medulares também foram verificados em 3 pacientes.The diagnosis of brain death is based in clinical, electroencephalographic and angiographic data. The criteria for diagnosis of brain death are: deep coma with unreceptivity and unresponsiveness, no movements or breathing (the patient's respiration must be maintained artificially, bilateral dilated and fixed pupils, absence of corneal reflexes, no response to caloric test, absence of deep tendon reflexes and of the superficial abdominal and plantar reflexes, isoelectric EEG maintained for twenty-four hours. The purpose of this study was to observe the natural clinical courses of 15 patients with brain death, specially the data concerning the deep and superficial reflexes. From 15 patients fulfilling the criteria of brain death, 8 maintained spinal reflexes up to the time of cardiac arrest; in five of these patients the superficial abdominal reflexes were present and the reflexes of spinal automatism could be elicited. These results show that the absence of deep and superficial reflexes can't be considered as essencial for the diagnosis of brain death.

  15. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O

    1991-01-01

    sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno......Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human...

  16. Auditory evoked blink reflex in peripheral facial paresis.

    Science.gov (United States)

    Ayta, Semih; Sohtaoğlu, Melis; Uludüz, Derya; Uygunoğlu, Uğur; Tütüncü, Melih; Akalin, Mehmet Ali; Kiziltan, Meral E

    2015-02-01

    The auditory blink reflex (ABR) is a teleceptive reflex consisting of an early brief muscle contraction of the orbicularis oculi in response to sound stimuli. Constriction of the orbicularis oculi in response to auditory stimulation is accepted as a part of the startle reaction. The blink reflex and ABR might share a final common pathway, consisting of facial nerve nuclei and the facial nerve and may have common premotor neurons. In this study, the authors evaluated the value of the ABR in patients with peripheral facial palsy (PFP), cross-checking the results with commonly used blink reflex changes. In total, 83 subjects with PFP and 34 age-matched healthy volunteers were included. Auditory blink reflex was elicited in all control subjects and in 36 PFP cases on the paralytic sides (43.3%), whereas it was asymmetric in 30.1% of the patients. Auditory blink reflex positivity was significantly lower in PFP cases with increasing severity. Blink reflex results were largely correlated with ABR positivity. Auditory blink reflex is a useful readily elicited and sensitive test in PFP cases, providing parallel results to blink reflex and being affected by disease severity.

  17. Timing of changes from a primitive reflex to a voluntary behavior in infancy as a potential predictor of socio-psychological and physical development during juvenile stages among common marmosets

    Directory of Open Access Journals (Sweden)

    Genta Karino

    2015-07-01

    Consequently, we found that both subjects expressed climbing-up behavior in the initial early period, but only the female who developed typically later, switched to jumping-down behavior with pre-facing to ‘down’ direction. Meanwhile, the male who would have developmental delay later, clearly did not show the switching pattern. The results suggest that the switch timing from involuntary to voluntary movement may be a possible predictor of juvenile and adolescent physiological and psychological retardation. The results also suggest that the primate model allows more methods to be developed for early detection of developmental disabilities that could be utilized in humans to pave the way for interventions and possible psychological or psychiatric treatment.

  18. Effects of replicating primary-reflex movements on specific reading difficulties in children: a randomised, double-blind, controlled trial.

    Science.gov (United States)

    McPhillips, M; Hepper, P G; Mulhern, G

    2000-02-12

    Children with specific reading difficulties have problems that extend beyond the range of underlying language-related deficits (eg, they have difficulties with balance and motor control). We investigated the role of persistent primary reflexes (which are closely linked in the earliest months of life to the balance system) in disrupting the development of reading skills. We assessed the efficacy of an intervention programme based on replicating the movements generated by the primary-reflex system during fetal and neonatal life. A randomised, individually matched, double-blind, placebo-controlled design was used and children (aged 8-11 years) with persistent primary reflexes and a poor standard of reading were enrolled into one of three treatment groups: experimental (children were given a specific movement sequence); placebo-control (children were given non-specific movements); and control (no movements). From an initial sample of 98 children, 60 children, 20 in each group were matched on age, sex, verbal intelligence quotient (IQ), reading ability, and persistent asymmetrical tonic neck reflex. For asymmetrical tonic neck-reflex levels there was a significant (group by time) interaction (pchildren. In particular, our study highlights how the educational functioning of children may be linked to interference from an early neurodevelopmental system (the primary-reflex system). A new approach to the treatment of children with reading difficulties is proposed involving assessment of underlying neurological functioning, and appropriate remediation.

  19. Head movements evoked in alert rhesus monkey by vestibular prosthesis stimulation: implications for postural and gaze stabilization.

    Directory of Open Access Journals (Sweden)

    Diana E Mitchell

    Full Text Available The vestibular system detects motion of the head in space and in turn generates reflexes that are vital for our daily activities. The eye movements produced by the vestibulo-ocular reflex (VOR play an essential role in stabilizing the visual axis (gaze, while vestibulo-spinal reflexes ensure the maintenance of head and body posture. The neuronal pathways from the vestibular periphery to the cervical spinal cord potentially serve a dual role, since they function to stabilize the head relative to inertial space and could thus contribute to gaze (eye-in-head + head-in-space and posture stabilization. To date, however, the functional significance of vestibular-neck pathways in alert primates remains a matter of debate. Here we used a vestibular prosthesis to 1 quantify vestibularly-driven head movements in primates, and 2 assess whether these evoked head movements make a significant contribution to gaze as well as postural stabilization. We stimulated electrodes implanted in the horizontal semicircular canal of alert rhesus monkeys, and measured the head and eye movements evoked during a 100 ms time period for which the contribution of longer latency voluntary inputs to the neck would be minimal. Our results show that prosthetic stimulation evoked significant head movements with latencies consistent with known vestibulo-spinal pathways. Furthermore, while the evoked head movements were substantially smaller than the coincidently evoked eye movements, they made a significant contribution to gaze stabilization, complementing the VOR to ensure that the appropriate gaze response is achieved. We speculate that analogous compensatory head movements will be evoked when implanted prosthetic devices are transitioned to human patients.

  20. Reflex sympathetic dystrophy and cigarette smoking.

    Science.gov (United States)

    An, H S; Hawthorne, K B; Jackson, W T

    1988-05-01

    Although the cause of reflex sympathetic dystrophy (RSD) remains unknown, hyperactivity of the sympathetic nerves and secondary vasospasm may be pathogenic in this syndrome. A retrospective epidemiologic study of RSD was done on 53 in-patients from 1978-1985. Cigarette smoking was strikingly increased in patient frequency in RSD (68% versus 37% of hospitalized controls, p less than 0.0001). Eighty-seven percent of the patients had a history of trauma or surgery, and 38% had other associated diseases. Cigarette smoking is statistically linked to RSD and may be involved in its pathogenesis by enhancing sympathetic activity, vasoconstriction, or by some other unknown mechanism.

  1. Reflexive regulation of CSR to promote sustainability

    DEFF Research Database (Denmark)

    Buhmann, Karin

    2011-01-01

    This article discusses Corporate Social Responsibility (CSR) from the perspective of governmental regulation as a measure to promote public policy interests through public-private regulation intended to influence firms’ self-regulation. Presenting a ‘government case’ for CSR, the connection between...... in understanding the mechanisms by which public authorities seek to influence firm’s behaviour through CSR in order to promote public policy objectives. The analysis indicates that to be effective, reflexive regulatory approaches to public-private regulation should pay careful attention to procedural design...

  2. Reflexive regulation of CSR to promote sustainablility

    DEFF Research Database (Denmark)

    Buhmann, Karin

    This article discusses Corporate Social Responsibility (CSR) from the perspective of governmental regulation as a measure to promote public policy interests through public-private regulation intended to influence firms’ self-regulation. Presenting a ‘government case’ for CSR, the connection between...... in understanding the mechanisms by which public authorities seek to influence firm’s behaviour through CSR in order to promote public policy objectives. The analysis indicates that to be effective, reflexive regulatory approaches to public-private regulation should pay careful attention to procedural design...

  3. Reflexivity in the Interstices: A Tale of Reflexivity at Work in, during, and behind the Scenes

    Science.gov (United States)

    Wickens, Corrine M.; Cohen, James A.; Walther, Carol S.

    2017-01-01

    This article is a story of how the authors came to make sense of the significance of those words in relation to gender, race/ethnicity, and citizenship in writing a manuscript about L[subscript 1]L[subscript 2] acquisition. It is a tale about how Reflexivity wove itself into the conversations, into the writing, into the in-between spaces, the…

  4. A multiparametric analysis of occlusal and periodontal jaw reflex characteristics in young adults with normal occlusion.

    Science.gov (United States)

    Suda, S; Matsugishi, K; Seki, Y; Sakurai, K; Suzuki, T; Morita, S; Hanada, K; Hara, K

    1997-08-01

    Periodontal jaw reflex, duration of percussion sounds, tooth mobility, and time-moment analysis of occlusal contacts by the T-scan system was recorded in nine periodontally healthy volunteers. The results showed that (i) reflex responses to the pressure applied to the uppercentageral incisors in the lingolabial direction varied, depending on the background jaw-clenching force (BCF) of the same-sided first molars. The BCF levels to elicit excitatory reflexes were 6-8 Kgf, and inhibitory reflexes were clearly elicited with a BCF of 10 Kgf and beyond. (ii) Duration of percussion sounds via an occlusal sound analyser (4.73-4.84 mS: upper first molars, 4.89-5.00 mS: uppercentageral incisors) and tooth mobility using a 'Periotest' (3.3-3.5: upper first molars, 5.5-5.6: uppercentageral incisors) showed a normal value. (iii) The time moments of occlusal contacts were symmetrical toward the midsagittal axis of the occlusal plane. The centre of the anteroposterior occlusal contacts was located in the first molar regions.

  5. BASIC CONCEPTS IN UNDERSTANDING RECOVERY OF FUNCTION IN VESTIBULAR REFLEX NETWORKS DURING VESTIBULAR COMPENSATION

    Directory of Open Access Journals (Sweden)

    Kenna ePeusner

    2012-02-01

    Full Text Available Unilateral peripheral vestibular lesions produce a syndrome of oculomotor and postural deficits with the symptoms at rest, the static symptoms, partially or completely normalizing shortly after the lesion due to a process known as vestibular compensation. The symptoms are thought to result from changes in the activity of vestibular sensorimotor reflexes. Since the vestibular nuclei must be intact for recovery to occur, many investigations have focused on studying these neurons after lesions. At present, the neuronal plasticity underlying early recovery from the static symptoms is not fully understood. Here we propose that knowledge of the reflex identity and input-output connections of the recorded neurons is essential to link the responses to animal behavior. We further propose that the cellular mechanisms underlying vestibular compensation can be sorted out by characterizing the synaptic responses and time course for change in morphologically-defined subsets of vestibular reflex projection neurons. Accordingly, this review focuses on the perspective gained by performing electrophysiological and immunolabeling studies on a specific subset of morphologically-defined, glutamatergic vestibular reflex projection neurons, the principal cells of the chick tangential nucleus. Reference is made to pertinent findings from other studies on vestibular nuclei neurons, but no comprehensive review of the literature is intended since broad reviews already exist. From recording excitatory and inhibitory spontaneous synaptic activity in principal cells, we find that the rebalancing of excitatory synaptic drive bilaterally is essential for vestibular compensation to proceed. This work is important for it defines for the first time the excitatory and inhibitory nature of the changing synaptic inputs and the time course for changes in a morphologically-defined subset of vestibular reflex projection neurons during early stages of vestibular compensation.

  6. Cough reflex changes in local tracheitis.

    Science.gov (United States)

    Hanácek, J; Porubanová, M; Korec, L; Beseda, O

    1979-01-01

    The authors describe changes in the cough reflex in unanaesthetized cats with experimental local tracheitis. Inflammation was produced by a silk suture fixed in the trachea and cough was elicited by mechanical stimulation of different parts of the respiratory tract mucosa. The resultant cough values (the number of efforts, the intensity of the maximum effort and the intensity of the attack) were compared with the corresponding values in healthy cats. In animals with a tracheal suture, inflammation was confined to the trachea. The intensity of cough elicited by stimulation of this region increased significantly compared with normal (on the 15th to 17th day of inflammation), whereas cough elicited from the laryngopharyngeal and tracheobronchial region did not. On about the 20th day of inflammation the authors found a decrease in the intensity of the maximum effort of cough elicited from the inflamed part of the trachea and a decrease in the intensity of the maximum effort and the intensity of the coughing attack elicited from the laryngopharyngeal and tracheobronchial region. They assume that the decrease could have been due to the development of protective inhibition in central structures participating in integration of the cough reflex.

  7. Reflexivity and adjustment strategies at the interfaces

    Directory of Open Access Journals (Sweden)

    Ismael Teomiro

    2011-10-01

    Full Text Available I argue in this work that Reinhart & Reuland’s (1993 conditions A and B hold for Spanish. I provide evidence supporting the hypothesis that this language makes use of both SE and SELF-anaphors. Inherent reflexive verbs undergo an internal argument reduction operation in the lexicon. However, the syntax always requires two arguments. Therefore certain clitics, which are SE-anaphors, are inserted in these derivations. This is a last-resort mechanism that makes an adjustment between the valence of the lexical entry of the verb and the requirements of the syntax in order for the derivation to converge at the C-I interface. These clitics are syntactic arguments. Nevertheless, they are not interpreted as semantic arguments since they violate the double chain condition, which forces nominal elements to share both a tense and thematic features with the verb and the tense heads. Non- inherent reflexive verbs require the presence of a SELF-anaphor, which is formed out of a SE-anaphor along with a protector SELF element. Therefore, both syntactic elements are interpreted as two distinguishable semantic elements at C-I despite the fact that there is binding between them both. The interpretation of both syntactic elements as just one semantic element is a pragmatic epiphenomenon.

  8. Era uma vez: reflexões sobre uma obra prima da literatura para a infância italiana: Pinóquio - There was once upon a time: reflections on a masterpiece of italian children’s literature: Pinocchio

    Directory of Open Access Journals (Sweden)

    Alessandra Avanzini, Italia

    2014-09-01

    Full Text Available Neste artigo discutirei o romance Le avventure di Pinocchio: storia di un burattino, escrito por Collodi, que apareceu inicialmente em forma seriada no Il giornale per i bambini, uma revista infantil publicada em 1883. Gostaria de começar com a seguinte pergunta: podemos considerar Pinóquio um Bildungsroman, uma história de formação? Mostrarei que é difícil fazê-lo, principalmente, devido ao fato de que Pinóquio não muda. A segunda pergunta à qual gostaria de responder é se esse romance é um romance para crianças. Discutirei que, na verdade, Pinóquio é um livro contra as crianças, um livro que não leva em conta a natureza e os sentimentos do pobre menino, mas simplesmente busca forçá-lo a adaptar-se ao mundo que o cerca. Esse mundo é constituído por valores específicos e certezas que Pinóquio não consegue entender durante todo o decorrer da história: a lógica de causa-efeito e a visão prática do mundo como uma entidade econômica. São esses os mesmos valores e certezas que caracterizam o período pós-Risorgimento, a partir de 1861, e a busca da nação italiana. Pinóquio não os entende, mas, depois de passar por muitas adversidades, durante as suas aventuras, decide aceitá-los como se fossem o seu mundo interior.Palavras-chave: Pinóquio, Collodi, literatura infantil, Itália, educação, século 19.THERE WAS ONCE UPON A TIME: REFLECTIONS ON A MASTERPIECE OF ITALIAN CHILDREN’S  LITERATURE: PINOCCHIOAbstractIn this article I will discuss the novel Le avventure di Pinocchio: storia di un burattino by Collodi, that firstly appeared serialized in Il giornale per i bambini, a children’s magazine, and was published in 1883. I would like to start from the following question: can we consider Pinocchio a Bildungsroman? And I’ll show that it is hardly possible to do so, for the reasons that I am going to discuss mainly due to the fact that there is no change in Pinocchio. The second question I would like to answer

  9. Medullary mediation of the laryngeal adductor reflex: A possible role in sudden infant death syndrome.

    Science.gov (United States)

    Wang, Xiaolu; Guo, Ruichen; Zhao, Wenjing; Pilowsky, Paul M

    2016-06-01

    The laryngeal adductor reflex (LAR) is a laryngeal protective reflex. Vagal afferent polymodal sensory fibres that have cell bodies in the nodose ganglion, originate in the sub-glottal area of the larynx and upper trachea. These polymodal sensory fibres respond to mechanical or chemical stimuli. The central axons of these sensory vagal neurons terminate in the dorsolateral subnuclei of the tractus solitarius in the medulla oblongata. The LAR is a critical, reflex in the pathways that play a protective role in the process of ventilation, and the sychronisation of ventilation with other activities that are undertaken by the oropharyngeal systems including: eating, speaking and singing. Failure of the LAR to operate properly at any time after birth can lead to SIDS, pneumonia or death. Despite the critical nature of this reflex, very little is known about the central pathways and neurotransmitters involved in the management of the LAR and any disorders associated with its failure to act properly. Here, we review current knowledge concerning the medullary nuclei and neurochemicals involved in the LAR and propose a potential neural pathway that may facilitate future SIDS research. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Evolutionary transition from biological to social systems via generation of reflexive models of externality.

    Science.gov (United States)

    Igamberdiev, Abir U

    2017-12-01

    Evolutionary transition from biological to social systems corresponds to the emergence of the structure of subject that incorporates the internal image of the external world. This structure, established on the basis of referral of the subject (self) to its symbolic image, acquires a potential to rationally describe the external world through the semiotic structure of human language. It has been modelled in reflexive psychology using the algebra of simple relations (Lefebvre, V.A., J. Soc. Biol. Struct. 10, 129-175, 1987). The model introduces a substantial opposition of the two basic complementary types of reflexion defined as Western (W) and Eastern (E). These types generate opposite models of behavior and opposite organizations of societies. Development of human societies involves the interactions of W and E types not only between the societies but also within one society underlying its homeostasis and dynamics. Invention of new ideas and implementation of new technologies shift the probability pattern of reflexive choices, appearing as internal assessments of the individual agents within a society, and direct changes in the preference of reflexive types. The dynamics of societies and of interactions between societies is based on the interference of opposite reflexive structures and on the establishment of different patterns during such interference. At different times in the history of human civilization these changing patterns resulted in the formation and splitting of large empires, the development and spreading of new technologies, the consecutive periods of wellness and decline. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Changes in H-reflex amplitude to muscle stretch and lengthening in humans.

    Science.gov (United States)

    Budini, Francesco; Tilp, Markus

    2016-07-01

    Spinal reflex excitability is traditionally assessed to investigate neural adjustments that occur during human movement. Different experimental procedures are known to condition spinal reflex excitability. Among these, lengthening movements and static stretching the human triceps have been investigated over the last 50 years. The purpose of this review is to shed light on several apparent incongruities in terms of magnitude and duration of the reported results. In the present review dissimilarities in neuro-spinal changes are examined in relation to the methodologies applied to condition and measure them. Literature that investigated three different conditioning procedures was reviewed: passive dorsiflexion, active dorsiflexion through antagonists shortening and eccentric plantar-flexors contractions. Measurements were obtained before, during and after lengthening or stretching. Stimulation intensities and time delays between conditioning procedures and stimuli varied considerably. H-reflex decreases immediately as static stretching is applied and in proportion to the stretch degree. During dorsiflexions the inhibition is stronger with greater dorsiflexion angular velocity and at lower nerve stimulation intensities, while it is weaker if any concomitant muscle contraction is performed. Within 2 s after a single passive dorsiflexion movement, H-reflex is strongly inhibited, and this effect disappears within 15 s. Dorsiflexions repeated over 1 h and prolonged static stretching training induce long-lasting inhibition. This review highlights that the apparent disagreement between studies is ascribable to small methodological differences. Lengthening movements and stretching can strongly influence spinal neural pathways. Results interpretation, however, needs careful consideration of the methodology applied.

  12. Bourdieu and Science Studies: Toward a Reflexive Sociology

    Science.gov (United States)

    Hess, David J.

    2011-01-01

    Two of Bourdieu's fundamental contributions to science studies--the reflexive analysis of the social and human sciences and the concept of an intellectual field--are used to frame a reflexive study of the history and social studies of science and technology as an intellectual field in the United States. The universe of large, Ph.D.-granting…

  13. (Re)constructing Reflexivity: A Relational Constructionist Approach

    NARCIS (Netherlands)

    Hosking, D.M.; Pluut, B.

    2010-01-01

    This article distinguishes three discourses of reflexivity in relation to human inquiry. One of these arises from a post-modern, relational constructionist perspective which radically re-conceptualizes reflexivity: (a) as a local and co-constructed process oriented towards the question (b) how are

  14. Reflex sympathetic dystrophy: Early treatment and psychological aspects

    NARCIS (Netherlands)

    Geertzen, J.H.B.; De Bruijn, H.; De Bruijn-Kofman, A.T.; Arendzen, J.H.

    1994-01-01

    We report the results of two prospective studies of early treatment and psychological aspects in a series of 26 patients with sympathetic reflex dystrophy of the hand in which treatment was started within 3 months after diagnosis. Ismelin blocks is an often used therapy in sympathetic reflex

  15. Can Treadmill Perturbations Evoke Stretch Reflexes in the Calf Muscles?

    NARCIS (Netherlands)

    Sloot, L.H.; van den Noort, J.C.; van der Krogt, M.M.; Bruijn, S.M.; Harlaar, J.

    2015-01-01

    Disinhibition of reflexes is a problem amongst spastic patients, for it limits a smooth and efficient execution of motor functions during gait. Treadmill belt accelerations may potentially be used to measure reflexes during walking, i.e. by dorsal flexing the ankle and stretching the calf muscles,

  16. Low Incidence Of Extensor Plantar Reflex In Newborns In An ...

    African Journals Online (AJOL)

    Background The plantar reflex has been reported to be predominantly flexor in African infants and in African subjects with lesions of the corticospinal tracts. This study was done to determine the incidence of extensor plantar reflex in healthy full-term newborns in an indigenous African population. Methods Healthy term ...

  17. Modulation of spinal reflexes by sexual films of increasing intensity

    NARCIS (Netherlands)

    Both, Stephanie; Boxtel, Geert; Stekelenburg, Jeroen; Everaerd, Walter; Laan, Ellen

    2005-01-01

    Sexual arousal can be viewed as an emotional state generating sex-specific autonomic and general somatic motor system responses that prepare for sexual action. In the present study modulation of spinal tendious (T) reflexes by sexual films of varying intensity was investigated. T reflexes were

  18. On the Property of Reflexivity for Multiplication Operators on Banach ...

    Indian Academy of Sciences (India)

    21

    operator Mz are reflexive on a Banach space of functions analytic on a plane domain. AMS Subject Classification: 47B37; 46A25. Keywords: Banach spaces of analytic functions, multiplication operators, reflexive oper- ator, multipliers, Caratheodory hull, bounded point evaluation, spectral set. Introduction. For any set E and ...

  19. Reflexive Pronouns in Dagbani | Issah | Legon Journal of the ...

    African Journals Online (AJOL)

    I argue that reflexives are formed by suffixing the reflexivizer, ma.a, meaning eselff, to the possessive pronominal. The pronominal varies in form depending on the singularity or plurality of the antecedent. I minimally compare reflexive pronouns with pronouns within the Binding Theory and observe that whilst pronouns are ...

  20. The Role of Transformational Leadership in Enhancing Team Reflexivity

    NARCIS (Netherlands)

    M.C. Schippers (Michaéla); D.N. den Hartog (Deanne); P.L. Koopman (Paul); D.L. van Knippenberg (Daan)

    2007-01-01

    textabstractTeam reflexivity, or the extent to which teams reflect upon and modify their functioning, has been identified as a key factor in the effectiveness of work teams. As yet, however, little is known about the factors that play a role in enhancing team reflexivity, and it is thus important to

  1. Space charge equation calculations for the reflex triode

    Energy Technology Data Exchange (ETDEWEB)

    Shearer, J.W.

    1976-09-01

    The Poisson equation solution of the space charge problem for the reflex triode is reviewed and illustrated with a number of examples. The numerical calculation technique for obtaining these results is briefly described. The results show that the characteristics of the triode are strong functions of the reflex-electron kinetic-energy spectrum, especially of the high-energy electrons.

  2. Effects of Lateral Funiculus Sparing, Spinal Lesion Level, and Gender on Recovery of Bladder Voiding Reflexes and Hematuria in Rats

    Science.gov (United States)

    Ferrero, Sunny L.; Brady, Tiffany D.; Dugan, Victoria P.; Armstrong, James E.; Hubscher, Charles H.

    2015-01-01

    Abstract Deficits in bladder function are complications following spinal cord injury (SCI), severely affecting quality of life. Normal voiding function requires coordinated contraction of bladder and urethral sphincter muscles dependent upon intact lumbosacral reflex arcs and integration of descending and ascending spinal pathways. We previously reported, in electrophysiological recordings, that segmental reflex circuit neurons in anesthetized male rats were modulated by a bilateral spino-bulbo-spinal pathway in the mid-thoracic lateral funiculus. In the present study, behavioral measures of bladder voiding reflexes and hematuria (hemorrhagic cystitis) were obtained to assess the correlation of plasticity-dependent recovery to the degree of lateral funiculus sparing and mid-thoracic lesion level. Adult rats received mid-thoracic-level lesions at one of the following severities: complete spinal transection; bilateral dorsal column lesion; unilateral hemisection; bilateral dorsal hemisection; a bilateral lesion of the lateral funiculi and dorsal columns; or a severe contusion. Voiding function and hematuria were evaluated by determining whether the bladder was areflexic (requiring manual expression, i.e., “crede maneuver”), reflexive (voiding initiated by perineal stroking), or “automatic” (spontaneous voiding without caretaker assistance). Rats with one or both lateral funiculi spared (i.e., bilateral dorsal column lesion or unilateral hemisection) recovered significantly faster than animals with bilateral lateral funiculus lesions, severe contusion, or complete transection. Bladder reflex recovery time was significantly slower the closer a transection lesion was to T10, suggesting that proximity to the segmental sensory and sympathetic innervation of the upper urinary tract (kidney, ureter) should be avoided in the choice of lesion level for SCI studies of micturition pathways. In addition, hematuria duration was significantly longer in males, compared to

  3. Voluntary Control of the Near Reflex: A Case Report

    Directory of Open Access Journals (Sweden)

    Serpil Akar

    2014-03-01

    Full Text Available Spasm of the near reflex is a rare disorder that involves intermittent and variable episodes of esotropia, pseudomyopia, and pupillary myosis. It is usually functional in origin and is seen mainly in young patients. Treatment options for spasm of the near reflex have had variable success. In instances where the etiology of spasm of the near reflex was suspected to be hysteria, psychotherapy has proven beneficial. We report the case of an 11-year-old girl who had functional spasm of the near reflex. The symptoms persisted for two years. Symptomatic relief was achieved by cycloplegia and spectacle correction (added plus lenses at near. The patient also underwent psychological counseling. In our case, the functional spasm of the near reflex spontaneously resolved after 2 years. (Turk J Ophthalmol 2014; 44: 161-3

  4. Prevalence of family history in patients with reflex syncope

    DEFF Research Database (Denmark)

    Holmegard, Haya N; Benn, Marianne; Kaijer, Michelle Nymann

    2013-01-01

    Reflex syncope is defined by a rapid transient loss of consciousness caused by global cerebral hypoperfusion resulting from vasodilatation and/or bradycardia attributable to inappropriate cardiovascular reflexes. A hereditary component has been suggested, but prevalence of family history may differ...... among subtypes of reflex syncope, as these have different autonomic responses and pathogeneses may be diverse. The present study aimed to assess the prevalence of a positive family history of syncope and cardiovascular characteristics in patients with cardioinhibitory and vasodepressor reflex syncope....... Patients (n=74) were classified into subtypes of reflex syncope - cardioinhibition/asystole (Vasovagal Syncope International Study subtypes II-B [VASIS II-B], n=38) or vasodepressor (VASIS III, n=36) - using the head-up tilt test. Family history was obtained by questionnaires supplemented by interview...

  5. Relationship between Human Pupillary Light Reflex and Circadian System Status

    Science.gov (United States)

    Bonmati-Carrion, Maria Angeles; Hild, Konstanze; Isherwood, Cheryl; Sweeney, Stephen J.; Revell, Victoria L.; Skene, Debra J.; Rol, Maria Angeles; Madrid, Juan Antonio

    2016-01-01

    Intrinsically photosensitive retinal ganglion cells (ipRGCs), whose photopigment melanopsin has a peak of sensitivity in the short wavelength range of the spectrum, constitute a common light input pathway to the olivary pretectal nucleus (OPN), the pupillary light reflex (PLR) regulatory centre, and to the suprachiasmatic nuclei (SCN), the major pacemaker of the circadian system. Thus, evaluating PLR under short wavelength light (λmax ≤ 500 nm) and creating an integrated PLR parameter, as a possible tool to indirectly assess the status of the circadian system, becomes of interest. Nine monochromatic, photon-matched light stimuli (300 s), in 10 nm increments from λmax 420 to 500 nm were administered to 15 healthy young participants (8 females), analyzing: i) the PLR; ii) wrist temperature (WT) and motor activity rhythms (WA), iii) light exposure (L) pattern and iv) diurnal preference (Horne-Östberg), sleep quality (Pittsburgh) and daytime sleepiness (Epworth). Linear correlations between the different PLR parameters and circadian status index obtained from WT, WA and L recordings and scores from questionnaires were calculated. In summary, we found markers of robust circadian rhythms, namely high stability, reduced fragmentation, high amplitude, phase advance and low internal desynchronization, were correlated with a reduced PLR to 460–490 nm wavelengths. Integrated circadian (CSI) and PLR (cp-PLR) parameters are proposed, that also showed an inverse correlation. These results demonstrate, for the first time, the existence of a close relationship between the circadian system robustness and the pupillary reflex response, two non-visual functions primarily under melanopsin-ipRGC input. PMID:27636197

  6. Effect of locally applied prazosin on the kinetics of the pupillary light reflex

    Science.gov (United States)

    MORTLOCK, S-A; LANGLEY, R W; BRADSHAW, C M; SZABADI, E

    1996-01-01

    The effect of locally applied prazosin on pupillometric measures was studied in healthy volunteers, in an attempt to identify the role of α1-adrenoceptors in the recovery time of the light reflex. Prazosin antagonized the mydriatic effect of phenylephrine, but did not alter that of tropicamide. Miotic responses to a range of light stimuli were measured under ambient temperature conditions of 22° C and 40° C. The 40° C condition was associated with shorter recovery times of the light reflex; prazosin increased the recovery time under both temperature conditions. Response amplitude was not affected by the temperature condition or prazosin. The results are consistent with the hypothesis that sympathetic neuromuscular transmission is involved in the redilatation of the pupil following a miotic response to light stimulation. PMID:8864324

  7. Reflex sympathetic dystrophy after a burn injury.

    Science.gov (United States)

    van der Laan, L; Goris, R J

    1996-06-01

    Reflex sympathetic dystrophy (RSD) is a disease that can appear after minor trauma or operation to an extremity. The injury may vary from a simple contusion to a fracture. The prevalence of burns as a cause of RSD, within a population of 829 patients with RSD, was studied retrospectively. Prospectively, we documented the medical history, signs and symptoms of all patients with RSD, seen by our department during the period from January 1984 to 31 December 1994. Four patients had developed RSD after a burn injury, resulting in a prevalence of 0.5 per cent. Though the clinical signs of early RSD are similar to those of a (thermal) burn, alertness to recognize inflammatory signs, in combination with the increase in complaints after exercise, is necessary for early diagnosis and treatment of the complicating RSD.

  8. Cocaine-induced reflex sympathetic dystrophy.

    Science.gov (United States)

    Gay, D; Singh, A

    2000-11-01

    Reflex sympathetic dystrophy (RSD) usually follows traumatic injuries or neurologic disorders. The authors report a rare case of RSD that followed intraarterial administration of cocaine in a patient with a history of intravenous drug abuse. The cocaine was self-administered inadvertently into the femoral artery rather than the femoral vein. Despite the intense pain, swelling, and dermatologic changes that followed, the diagnosis of RSD was not considered until scintigraphic studies suggested it. A combination of normal radiographs, a normal leukocyte study, and an abnormal bone scan in the region of tenderness and swelling excluded other possibilities and suggested RSD. In our patient, RSD was likely caused by an ischemic autonomic injury from the vasoconstrictor action of cocaine. Clinical follow-up and relief using phentolamine, an alpha-adrenergic blocker and vasodilator, made the diagnosis of RSD most likely.

  9. The Disappearing Audience and Reflexive Visibility

    Directory of Open Access Journals (Sweden)

    Katerina Girginova

    2016-08-01

    Full Text Available Contrary to popular opinion and some academic writing that celebrates the renewed visibility of new media audiences, this essay argues that they are increasingly going into retreat. To understand how new media audiences “disappear” from view of one another, I borrow from Brighenti’s typology of visibility and develop the idea of “reflexive visibility.” The latter describes the ability to socially orient ourselves in a digital environment through the textual and contextual cues of others—an activity that is of utmost importance not only to researchers wishing to “see” various audiences but also for audiences writ large, wishing to know themselves.

  10. Reflexivity and vulnerability in collaborative knowledge production

    DEFF Research Database (Denmark)

    Jakobsen, Helle Nordentoft; Olesen, Birgitte Ravn

    -reports of positive learning outcomes and fails to illuminate how power is always at play leaving certain participants exposed and potentially vulnerable (Fenwick, 2008). As such, it remains unclear how power relations unfold in moment-by-moment interactions including how the researcher’s position matters...... because their voices are subjugated and they appear to be vulnerable. The extent of this development in the peer interactions and the reproductive nature of the knowledge produced were unexpected. In other words we – the researchers – became struck in the analytical process. In the final part of the paper......, we discuss how the reproduction of power relations invokes ethical concerns and raises critical perspectives on the undeniable common good of collaborative research in which participants’ vulnerability may be overlooked in potentially reflexive moments (Nordentoft and Kappel, 2011). Still, we find...

  11. Somatosensory imprinting in spinal reflex modules.

    Science.gov (United States)

    Schouenborg, Jens

    2003-05-01

    Understanding how sensory information is used by motor systems for motor commands requires detailed knowledge about how the body shape and biomechanics are represented in the motor circuits. We have used the withdrawal reflex system as a model for studies of sensorimotor transformation. This system has a modular organisation in the adult. Each module performs a detailed and functionally adapted sensorimotor transformation related to the withdrawal efficacy of its output muscle(s). The weight distribution of the cutaneous input to a module is determined by the pattern of withdrawal efficacy of the muscle. Recently, we found that the somatotopic organisation and weight of the cutaneous input to the dorsal horn of the lower lumbar cord is related to this modular organisation. The dorsal horn in the lower lumbar cord thus appears to be organised in a column-like fashion, where each column performs a basic sensorimotor transformation related to the movement caused by a single muscle and the body shape. Since the withdrawal reflex system encodes error signals to the cerebellum through some of the spino-olivo cerebellar pathways, the modular concept is, in fact, a key to understanding sensory processing in higher order motor systems as well. Developmental studies indicate that each module is a self-organising circuitry that uses sensory feedback on muscle contractions to adjust its synaptic organisation. Furthermore, these studies suggest that the spontaneous movements during development, by providing structured sensory information related to movement pattern of single muscles and body shape, are instrumental in shaping the sensorimotor transformation in the spinal cord. These findings and their implications for the understanding of higher motor functions and their clinical aspects will be discussed.

  12. Prenatal exposure to a low fipronil dose disturbs maternal behavior and reflex development in rats.

    Science.gov (United States)

    Udo, Mariana S B; Sandini, Thaísa M; Reis, Thiago M; Bernardi, Maria Martha; Spinosa, Helenice S

    2014-01-01

    Fipronil (FPN) is a phenylpyrazole insecticide used in veterinary services and agriculture, and it is of considerable concern to public health. It inhibits the chloride channels associated with gamma-amino butyric acid (GABA) receptors in mammals and also inhibits the chloride channels associated with GABA and glutamate (Glu) receptors in insects. In this study, a commercial product containing fipronil was orally administered to pregnant Wistar rats at dose levels of 0.1, 1.0, or 10.0mg/kg/day from the sixth to twentieth day of gestation (n=10 pregnant rats/group). Its toxicity was evaluated based on maternal toxicity, reproductive quality, maternal behavior, and offspring physical as well as reflex development. All parameters observed in the observed offspring were assigned to one ink-marked couple in each litter (n=20 animals/group - 10 males and 10 females). The offspring couple represented the litter. Slight maternal toxicity presented during the second week of gestation for each fipronil dose and during the third gestational week at the highest dose due to lower chow intake. However, no effects were observed for gestational weight gain or gestation time, and the reproductive quality was not impaired, which suggests no adverse maternal effects from the doses during pregnancy. Moreover, the lowest fipronil dose compromised the active and reflexive maternal responses, but the highest dose induced a stereotyped active response without interfering in the reflexive reaction. For offspring development, no differences in physical growth parameters were observed between the groups. However, considering reflex development, our results showed that negative geotaxis reflex development was delayed in the offspring at the lowest fipronil dose, and palmar grasp was lost earlier at the lowest and intermediate fipronil doses. These results suggest that the alterations observed herein may be due to either the GABAergic system or endocrine disruption, considering that fipronil

  13. Features of stimulus-specific seizures in dogs with reflex epilepsy: 43 cases (2000-2014).

    Science.gov (United States)

    Shell, Linda; Scariano, Rachel; Rishniw, Mark

    2017-01-01

    OBJECTIVE To describe the occurrence and management of reflex epilepsy (ie, seizure activity triggered by exposure to specific locations or situations) in dogs. DESIGN Retrospective case series. ANIMALS 43 client-owned dogs. PROCEDURES Discussions by veterinarians participating in the Veterinary Information Network online community for the years 2000 through 2014 were reviewed to identify dogs with a diagnosis of reflex epilepsy and seizure activity in response to stimuli. History, signalment (including age at onset), the specific stimulus or stimuli that provoked seizures, treatments, and any concurrent neurologic diagnoses were recorded. RESULTS A variety of breeds were affected. Median age at onset was 5 years (range, 3 months to 11 years). Reflex seizures were reported as being repeatedly triggered by visits to a veterinary clinic (35/43 dogs), grooming facility (24/43 dogs), or boarding facility (13/43 dogs) and, less commonly, by other situations (eg, pet store or car ride). Over half of the dogs (24/43) had multiple triggers. Eight (19%) dogs had seizures at other times that were not induced by location or a specific situation. A variety of sedatives and maintenance antiepileptic drugs administered to affected dogs failed to prevent the stimulus-specific seizure activity. CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study suggested that seizures provoked by specific situations or locations occur in dogs with reflex epilepsy and that common triggers were visits to veterinary and grooming facilities. Further studies are necessary to elucidate the characteristics of reflex epilepsy in dogs and to determine the most effective means to manage these patients.

  14. Different Effects of Cold Stimulation on Reflex and Non-Reflex Components of Poststroke Spastic Hypertonia

    Directory of Open Access Journals (Sweden)

    Sheng Li

    2017-04-01

    Full Text Available ObjectiveTo use an established biomechanical approach to quantify reflex and non-reflex responses from spastic–paretic elbow flexors in response to controlled cold and heat stimulation.MethodsThirteen spastic–hemiplegic stroke subjects were tested in the experiment. The spastic elbow joint was stretched into extension for 50° at two speeds (5°/s and 100°/s in a customized apparatus. Thermal stimulation (HEAT at heat pain threshold, COLD at 0°C, or BASELINE at room temperature was applied to the thenar eminence of the contralateral hand immediately prior to stretching for at least 30 s.ResultsTotal torque was greater at 100°/s than at 5°/s. Total torque was significantly increased after COLD, but not HEAT as compared to BASELINE. When normalized to total torque at baseline, HEAT decreased total torque by 6.3%, while COLD increased total torque by 11.0%. There was no significant difference in the reflex torque among three thermal conditions.ConclusionThe findings demonstrate differentiated effects of cold stimulation on the total resistance from spastic muscles. They provide objective evidence for anecdotal clinical observations of increased muscle spasticity by cold exposure.

  15. Tempos e espaços na organização curricular: uma reflexão sobre a dinâmica dos processos escolares Times and spaces in the curricular organization: a reflection about on the dynamics of school processes

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    Juares da Silva Thiesen

    2011-04-01

    Full Text Available O presente artigo apresenta uma reflexão sobre os conceitos de tempo e espaço na organização curricular com ênfase na dinâmica dos processos escolares. Destaca inicialmente como essas categorias foram concebidas durante a modernidade sob a influência do pensamento mecanicista/positivista, apontando as críticas que alguns pesquisadores atuais fazem dessa concepção. O texto argumenta em defesa de uma releitura desses mesmos conceitos na contemporaneidade, releitura essa que pode se traduzir em mudanças significativas nas formas de organização curricular na atualidade. Defende que a releitura dos conceitos de tempo e espaço curricular está sendo estimulada em contextos que incluem a democratização da informação via WWW, a globalização econômica, o desenvolvimento das tecnologias da informação e comunicação, a expansão da educação a distância e, muito expressivamente, as contribuições trazidas pelas atuais abordagens sobre currículo e sobre infância.The present article presents an overview of concepts of time and space in the curricular organization, with focus on the dynamics of schooling processes. It initially highlights how these aspects were conceived during modernity under the influence of the mechanicist/positivist thought, pointing out some of the criticisms to that conception by current researchers. The text indorses a rereading of such concepts in the present time, which may result in important changes in the current curricular organization. It indorses that the rereading of curricular time and space concepts is being stimulated in contexts that include information democratization through "WWW", economic globalization, development of communication and information technologies, expansion of Long Distance Education and, very expressively, the contributions of modern approaches about curriculum and about childhood.

  16. Intact thumb reflex in areflexic Guillain Barré syndrome: A novel phenomenon.

    Science.gov (United States)

    Naik, Karkal Ravishankar; Saroja, Aralikatte Onkarappa; Mahajan, Manik

    2014-04-01

    Areflexia is one of the cardinal clinical features for the diagnosis of Guillain Barré syndrome. However, some patients may have sluggish proximal muscle stretch reflexes. Presence of thumb reflex, a distal stretch muscle reflex has not been documented in Guillain Barré syndrome. We prospectively evaluated thumb reflex in Guillain Barré syndrome patients and age matched controls from April to September 2013. There were 31 patients with Guillain Barré syndrome in whom thumb reflex could be elicited in all (24 brisk, 7 sluggish), whereas all the other muscle stretch reflexes were absent in 29 patients at presentation and the remaining two had sluggish biceps and quadriceps reflexes (P = 0.001). Serial examination revealed gradual diminution of the thumb reflex (P thumb reflex. Thumb reflex, a distal stretch reflex is preserved in the early phase of Guillain Barré syndrome.

  17. Emetic stimulation inhibits the swallowing reflex in decerebrate rats.

    Science.gov (United States)

    Kurozumi, Chiharu; Yamagata, Ryuzo; Himi, Naoyuki; Koga, Tomoshige

    2008-06-01

    The effects of emetic stimulation on the swallowing reflex were investigated in decerebrated rats. Hypoxia, gastric distension and LiCl administration were used as emetic stimulations. The swallowing reflex was elicited by electrical stimulation of the superior laryngeal nerve (SLN, 20 Hz, 3-5 V, 0.3 ms duration) for 20 s. To examine the effect of hypoxia, nitrogen gas was inhaled under artificial ventilation. There were significantly fewer swallows during a decrease in PO(2) than under air ventilation (p<0.05). The number of swallows during 3-ml stomach distension was significantly lower than that before distension (p<0.05). Intravenous administration of LiCl (100 mg/kg) also significantly reduced the number of swallows (p<0.05). The combination of SLN stimulation and emetic stimuli occasionally produced burst activity of abdominal muscles, which might be associated with the gag reflex. Both the gag and swallowing reflexes are well known to be mediated by the nucleus of the solitary tract. The physiological roles of the gag reflex and the swallowing reflex are considered to be reciprocal. Taken together, these results suggest that emetic stimulation inhibits the swallowing pattern generator via the nucleus of the solitary tract, which in turn facilitates the gag reflex.

  18. Reflex anuria: an old concept with new evidence.

    Science.gov (United States)

    Hou, Weibin; Wen, Jin; Ji, Zhigang; Chen, Jian; Li, Hanzhong

    2014-02-01

    Reflex anuria (RA) was defined by Hull as cessation of urine output from both kidneys due to irritation or trauma to one kidney or its ureter, or severely painful stimuli to other organs. This is not a common concept among urologists or nephrologists even though it has been proposed for more than half a century. The phenomenon has not been thoroughly understood. But intrarenal arteriolar spasm and ureteral spasm have gained wide acceptance as the mechanisms of RA. The present review summarized papers published up to now on RA, in order to depict the general profile of the disease and to further elucidate the pathogenesis of RA. A classification system of RA was proposed as neurovascular reflex, ureterorenal reflex, radiated renovascular reflex, renoureteral reflex, ureteroureteral reflex and radiated ureteral reflex, based on the two assumed mechanisms and the stimulus' origins. All these types except renoureteral reflex had gained supporting evidence from animal experiments and/or clinical case reports. RA is a diagnosis of exclusion, only being considered after ruling out common and tangible etiologies such as ureteral calculi, acute tubular necrosis, renal vascular occlusion, hypovolemia, infection, etc. If the diagnosis has been established, treatment plan should be directed toward the mechanisms more than the causative factors. Abnormalities of the autonomic nerve system and congenital urogenital malformations incline people to RA. In summary, RA is a cessation of urine production caused by stimuli on kidney, ureter or other organs, through a mechanism of reflex spasm of intrarenal arterioles or ureters, leading to acute renal failure. It is a functional rather than parenchymal disease.

  19. Repeated elicitation of the acoustic startle reflex leads to sensitisation in subsequent avoidance behaviour and induces fear conditioning

    Directory of Open Access Journals (Sweden)

    Janik Vincent M

    2011-04-01

    Full Text Available Abstract Background Autonomous reflexes enable animals to respond quickly to potential threats, prevent injury and mediate fight or flight responses. Intense acoustic stimuli with sudden onsets elicit a startle reflex while stimuli of similar intensity but with longer rise times only cause a cardiac defence response. In laboratory settings, habituation appears to affect all of these reflexes so that the response amplitude generally decreases with repeated exposure to the stimulus. The startle reflex has become a model system for the study of the neural basis of simple learning processes and emotional processing and is often used as a diagnostic tool in medical applications. However, previous studies did not allow animals to avoid the stimulus and the evolutionary function and long-term behavioural consequences of repeated startling remain speculative. In this study we investigate the follow-up behaviour associated with the startle reflex in wild-captured animals using an experimental setup that allows individuals to exhibit avoidance behaviour. Results We present evidence that repeated elicitation of the acoustic startle reflex leads to rapid and pronounced sensitisation of sustained spatial avoidance behaviour in grey seals (Halichoerus grypus. Animals developed rapid flight responses, left the exposure pool and showed clear signs of fear conditioning. Once sensitised, seals even avoided a known food source that was close to the sound source. In contrast, animals exposed to non-startling (long rise time stimuli of the same maximum sound pressure habituated and flight responses waned or were absent from the beginning. The startle threshold of grey seals expressed in units of sensation levels was comparable to thresholds reported for other mammals (93 dB. Conclusions Our results demonstrate that the acoustic startle reflex plays a crucial role in mediating flight responses and strongly influences the motivational state of an animal beyond a short

  20. Reflex anuria: a rare cause of acute kidney injury.

    Science.gov (United States)

    Adediran, Samuel; Dhakarwal, Pradeep

    2014-01-01

    Acute Kidney Injury results from pre renal, post renal or intrinsic renal causes. Reflex anuria is a very rare cause of renal impairment which happens due to irritation or trauma to one kidney or ureter, or severely painful stimuli to other nearby organs. Here we present a case of acute kidney injury secondary to reflex anuria in a patient who underwent extensive gynecological surgery along with ureteral manipulation which recovered spontaneously. Reflex Anuria is a rare and often not considered as cause of acute kidney injury. This case illustrates that this should be kept as a differential in potential cause of acute kidney injury in patient undergoing urogenital or gynecological surgeries.

  1. The Effects of Attention on the Trigeminal Blink Reflex.

    Science.gov (United States)

    Schicatano, Edward J

    2016-04-01

    During top-down processing, higher cognitive processes modulate lower sensory processing. The present experiment tested the effects of directed attention on trigeminal reflex blinks in humans (n = 8). In separate sessions, participants either attended to blink-eliciting stimuli or were given no attentional instructions during stimulation of the supraorbital branch of the trigeminal nerve. Attention to blink-eliciting stimuli significantly increased reflex blink amplitude and duration and shortened blink latency compared with the no attention condition. These results suggested that higher processes such as attention can modify the trigeminal blink reflex circuit. © The Author(s) 2016.

  2. [Human physiology: images and practices of the reflex].

    Science.gov (United States)

    Wübben, Yvonne

    2010-01-01

    The essay examines the function of visualizations and practices in the formation of the reflex concept from Thomas Willis to Marshall Hall. It focuses on the specific form of reflex knowledge that images and practices can contain. In addition, the essay argues that it is through visual representations and experimental practices that technical knowledge is transferred to the field of human reflex physiology. When using technical metaphors in human physiology authors often seem to feel obliged to draw distinctions between humans, machines and animals. On closer scrutiny, these distinctions sometimes fail to establish firm borders between the human and the technical.

  3. Análise do tempo de resposta reflexa dos músculos estabilizadores patelares em indivíduos com síndrome da dor patelofemural Analysis of the reflex response time of the patellar stabilizer muscles in individuals with patellofemoral pain syndrome

    Directory of Open Access Journals (Sweden)

    D Bevilaqua-Grossi

    2008-02-01

    Full Text Available OBJETIVO: Avaliar o tempo de resposta reflexa (TRR dos músculos vasto medial oblíquo (VMO, vasto lateral oblíquo (VLO e vasto lateral longo (VLL em indivíduos clinicamente saudáveis e portadores de síndrome da dor patelofemural (SDPF. MÉTODOS: Foram avaliadas 12 mulheres clinicamente saudáveis e 12 mulheres com SDPF. Os registros eletromiográficos foram obtidos por eletrodos ativos simples conectados a um eletromiógrafo, acionados por um sensor externo fixado sobre a porção média do ligamento da patela a partir de sua percussão. A análise do TRR foi realizada por meio da medida do tempo zero ao pico da resposta elétrica dos músculos VMO, VLO e VLL, em segundos, para ambos os grupos. A análise estatística empregada foi o teste de análise de variância (ANOVA, pOBJECTIVE: To investigate the reflex response time (RRT of the vastus medialis obliquus (VMO, vastus lateralis obliquus (VLO and vastus lateralis longus (VLL muscles in clinically healthy individuals and subjects with patellofemoral pain syndrome (PPS. METHODS: Twelve clinically health women and twelve women with PPS were evaluated. Electromyography (EMG records were obtained using active electrodes connected to an electromyograph that was activated by an external sensor attached to the medial portion of the patella ligament, by means of percussion. The RRT was analyzed by measuring the time, in seconds, between zero and peak electrical response of the VMO, VLO and VLL muscles, for both groups. The statistical analysis consisted of analysis of variance (ANOVA, p< 0.05 and the Tukey post-hoc test (p< 0.05 to compare the response between muscles, and Student's t test (p< 0.05 to compare the response between groups. RESULTS: Both groups presented lower RRT for the VMO muscle than for the VLO and VLL muscles. However, no significant difference was seen between the VLO and VLL muscles. There was no significant difference in RRT between the groups. CONCLUSIONS: According to

  4. Effect of age-related hearing loss on the click-rate-induced facilitation of acoustic reflex thresholds.

    Science.gov (United States)

    Rawool, Vishakha Waman

    2017-07-01

    This investigation was designed to evaluate the effect of age-related hearing loss on the click-rate-induced improvement in the acoustic reflex thresholds. Case-control study. Data from five different adults ear-groups (15 ears each) were included in the study: 1. Younger with normal hearing. 2. Older with normal hearing. 3. Older with mild high-frequency loss. 4. Older with moderate high-frequency loss. 5. Older with low- and high-frequency loss. Ipsilateral acoustic reflex thresholds were obtained from the left and/or right ear/s by presenting clicks at the repetition rates of 50, 100, 150, 200 and 300 clicks/s. The rate-induced facilitation (RIF) was calculated by subtracting the lowest acoustic reflex threshold from the highest reflex threshold obtained across the various click-rates. The click-RIF is significantly reduced in older individuals compared to younger adults. There is no significant difference in RIF across the four older adult groups suggesting that an age-related, mild to moderate hearing loss has no significant effect on the click RIF of the acoustic reflex thresholds. Click-RIF may allow us to document the effect of ageing on temporal processing within the auditory brainstem area, in a time-efficient and objective manner using commercially available equipment.

  5. Progress toward development of a multichannel vestibular prosthesis for treatment of bilateral vestibular deficiency.

    Science.gov (United States)

    Fridman, Gene Y; Della Santina, Charles C

    2012-11-01

    This article reviews vestibular pathology and the requirements and progress made in the design and construction of a vestibular prosthesis. Bilateral loss of vestibular sensation is disabling. When vestibular hair cells are injured by ototoxic medications or other insults to the labyrinth, the resulting loss of sensory input disrupts vestibulo-ocular reflexes (VORs) and vestibulo-spinal reflexes that normally stabilize the eyes and body. Affected individuals suffer poor vision during head movement, postural instability, chronic disequilibrium, and cognitive distraction. Although most individuals with residual sensation compensate for their loss over time, others fail to do so and have no adequate treatment options. A vestibular prosthesis analogous to cochlear implants but designed to modulate vestibular nerve activity during head movement should improve quality of life for these chronically dizzy individuals. We describe the impact of bilateral loss of vestibular sensation, animal studies supporting feasibility of prosthetic vestibular stimulation, the current status of multichannel vestibular sensory replacement prosthesis development, and challenges to successfully realizing this approach in clinical practice. In bilaterally vestibular-deficient rodents and rhesus monkeys, the Johns Hopkins multichannel vestibular prosthesis (MVP) partially restores the three-dimensional (3D) VOR for head rotations about any axis. Attempts at prosthetic vestibular stimulation of humans have not yet included the 3D eye movement assays necessary to accurately evaluate VOR alignment, but these initial forays have revealed responses that are otherwise comparable to observations in animals. Current efforts now focus on refining electrode design and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimizing stimulus protocols to improve dynamic range and reduce excitation-inhibition asymmetry, and adapting laboratory MVP prototypes into devices

  6. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    Science.gov (United States)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed

  7. Parieto-occipital cortex shows early target selection to faces in a reflexive orienting task.

    Science.gov (United States)

    Morand, Stéphanie M; Harvey, Monika; Grosbras, Marie-Hélène

    2014-04-01

    It is well established that human faces induce stronger involuntary orienting responses than other visual objects. Yet, the timing of this preferential orienting response at the neural level is still unknown. Here, we used an antisaccade paradigm to investigate the neural dynamics preceding the onset of reflexive and voluntary saccades elicited by human faces and nonface visual objects, normalized for their global low-level visual properties. High-density event-related potentials (ERPs) were recorded in observers as they performed interleaved pro- and antisaccades toward a lateralized target. For reflexive saccades, we report an ERP modulation specific to faces as early as 40-60 ms following stimulus onset over parieto-occipital sites, further predicting the speed of saccade execution. This was not linked to differences in the programming of the saccadic eye movements, as it occurred early in time. For the first time, we present electrophysiological evidence of early target selection to faces in reflexive orienting responses over parieto-occipital cortex that facilitates the triggering of saccades toward faces. We argue for a 2-stage process in the representation of a face in involuntary spatial orienting with an initial, rapid implicit processing of the visual properties of a face, followed by subsequent stimulus categorization depicted by the N170 component.

  8. Central adaptation to repeated galvanic vestibular stimulation: implications for pre-flight astronaut training.

    Directory of Open Access Journals (Sweden)

    Valentina Dilda

    Full Text Available Healthy subjects (N = 10 were exposed to 10-min cumulative pseudorandom bilateral bipolar Galvanic vestibular stimulation (GVS on a weekly basis for 12 weeks (120 min total exposure. During each trial subjects performed computerized dynamic posturography and eye movements were measured using digital video-oculography. Follow up tests were conducted 6 weeks and 6 months after the 12-week adaptation period. Postural performance was significantly impaired during GVS at first exposure, but recovered to baseline over a period of 7-8 weeks (70-80 min GVS exposure. This postural recovery was maintained 6 months after adaptation. In contrast, the roll vestibulo-ocular reflex response to GVS was not attenuated by repeated exposure. This suggests that GVS adaptation did not occur at the vestibular end-organs or involve changes in low-level (brainstem-mediated vestibulo-ocular or vestibulo-spinal reflexes. Faced with unreliable vestibular input, the cerebellum reweighted sensory input to emphasize veridical extra-vestibular information, such as somatosensation, vision and visceral stretch receptors, to regain postural function. After a period of recovery subjects exhibited dual adaption and the ability to rapidly switch between the perturbed (GVS and natural vestibular state for up to 6 months.

  9. Vertigo and balance in children--diagnostic approach and insights from imaging.

    Science.gov (United States)

    Jahn, Klaus

    2011-07-01

    Common causes of vertigo and dizziness in childhood are vestibular migraine and associated syndromes (benign paroxysmal vertigo), unilateral vestibular failure due to labyrinthitis, positioning vertigo, and somatoform syndromes. Although the same spectrum of diseases as in adults can be found, the frequency differs widely. Further, balance disorders not related to vestibular function, like cerebral palsy, can present with dizziness. Vestibular function can reliably be addressed at the bedside by head impulses to test vestibulo-ocular reflex function, ocular motor testing of the central vestibular system, and balance tests for vestibulo-spinal function. Vestibulo-ocular reflex function can now be quantified by recording eye and head movements with high resolution video-oculography (256 Hz) and inertial sensors. Posturographic measures using artificial neuronal networks are used to classify dysbalance. Quantitative gait analysis further helps to distinguish balance disorders caused by e.g. sensory dysfunction or supraspinal disturbances. Recently, functional neuroimaging opened a view to the brain network for the control of posture and locomotion. From frontal cortex the locomotor signal is conveyed via the basal ganglia to the centers for locomotion and postural control in the brainstem tegmentum. The cerebellum is involved in sensory integration and rhythm generation during postural demands. To summarize, most syndromes causing dizziness, vertigo and imbalance can be diagnosed based on history and clinical tests. However, new data from neurophysiology and imaging help to understand the pathophysiology and the therapeutic principles in these disorders. Copyright © 2011 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

  10. Primitive Reflexes and Attention-Deficit/Hyperactivity Disorder: Developmental Origins of Classroom Dysfunction

    Science.gov (United States)

    Taylor, Myra; Houghton, Stephen; Chapman, Elaine

    2004-01-01

    The present research studied the symptomatologic overlap of AD/HD behaviours and retention of four primitive reflexes (Moro, Tonic Labyrinthine Reflex [TLR], Asymmetrical Tonic Neck Reflex [ATNR], Symmetrical Tonic Neck Reflex [STNR]) in 109 boys aged 7-10 years. Of these, 54 were diagnosed with AD/HD, 34 manifested sub-syndromal coordination,…

  11. Stretch reflex regulation in healthy subjects and patients with spasticity

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Petersen, Nicolas; Crone, Clarissa

    2005-01-01

    during voluntary muscle contraction in part because of depression of the inhibitory mechanisms that are affected in spasticity. In spastic patients, these inhibitory mechanisms are already depressed at rest and cannot be depressed further in connection with a contraction. In relation to most normal......In recent years, part of the muscle resistance in spastic patients has been explained by changes in the elastic properties of muscles. However, the adaptive spinal mechanisms responsible for the exaggeration of stretch reflex activity also contribute to muscle stiffness. The available data suggest...... of the spastic symptoms. A recent finding also shows no sign of exaggerated stretch reflexes in muscles voluntarily activated by the spastic patient in general. This is easily explained by the control of stretch reflex activity in healthy subjects. In healthy subjects, the stretch reflex activity is increased...

  12. Increased Auditory Startle Reflex in Children with Functional Abdominal Pain

    NARCIS (Netherlands)

    Bakker, Mirte J.; Boer, Frits; Benninga, Marc A.; Koelman, Johannes H. T. M.; Tijssen, Marina A. J.

    Objective To test the hypothesis that children with abdominal pain-related functional gastrointestinal disorders have a general hypersensitivity for sensory stimuli. Study design Auditory startle reflexes were assessed in 20 children classified according to Rome III classifications of abdominal

  13. Romantic relationships and their transformation in the reflexive society

    National Research Council Canada - National Science Library

    Lavinia Alexe

    2010-01-01

    .... Following Anthony Giddens (1992), who observed that increased autonomy and reflexivity were both elements that have shaken the romantic love, Jean-Claude Kaufmann notices the deep changes occurring in the way in which romantic...

  14. Interindividual differences in H reflex modulation during normal walking

    DEFF Research Database (Denmark)

    Simonsen, Erik B; Dyhre-Poulsen, Poul; Alkjaer, T

    2002-01-01

    Based on previous studies, at least two different types of soleus Hoffmann (H) reflex modulation were likely to be found during normal human walking. Accordingly, the aim of the present study was to identify different patterns of modulation of the soleus H reflex and to examine whether or not sub......Based on previous studies, at least two different types of soleus Hoffmann (H) reflex modulation were likely to be found during normal human walking. Accordingly, the aim of the present study was to identify different patterns of modulation of the soleus H reflex and to examine whether...... was greater for the S group. The hip joint moment was similar for the groups. The EMG activity in the vastus lateralis and anterior tibial muscles was greater prior to heel strike for the S group. These data indicate that human walking exhibits at least two different motor patterns as evaluated by gating...

  15. A tapetal-like fundus reflex in a healthy male

    DEFF Research Database (Denmark)

    Schatz, Patrik; Bregnhøj, Jesper; Arvidsson, Henrik Sven

    2012-01-01

    To report on the retinal function and structure in a 37-year-old male who presented with a tapetal-like reflex (TLR) indistinguishable from that seen in female carriers of X-linked retinitis pigmentosa (XLRP)....

  16. Reflex anuria affecting both kidneys following hysterectomy

    Directory of Open Access Journals (Sweden)

    Gholyaf Mahmoud

    2009-01-01

    Full Text Available In situations when there is unilateral ureteral obstruction, the contralateral kidney retains its normal function. In rare instances however, it has been reported that unilateral ureteral obstruction can lead to reflex anuria (RA and acute renal failure (ARF. Even more unusually, RA with ARF can occur without organic obstruction due to ureteric manipulation during pelvic surgery. We report a 78- year-old woman, who underwent hysterectomy because of endometrial carcinoma. She developed ARF evidenced by anuria of 120-hours duration, and gradual rise of serum creatinine levels to 11.8 mg/dL on the fifth day after hysterectomy. Ultrasound study of the urinary tract revealed bilateral moderate hydronephrosis. Detailed evaluation did not reveal any organic obstruc-tion. She was managed with hemodialysis, control of hypertension and correction of fluid and elec-trolyte imbalances. By the sixth day, diuresis was established, and the blood urea and serum crea-tinine levels decreased to normal by the sixteenth day. The patient was finally discharged on the eighteenth day. Our case suggests that urologists and nephrologists should consider RA as one of the causes of anuria and ARF.

  17. Reflex anuria affecting both kidneys following hysterectomy.

    Science.gov (United States)

    Gholyaf, Mahmoud; Afzali, Saeed; Babolhavaegi, Hoshang; Rahimi, Abolfazl; Wagharseyedayn, Seyed A

    2009-01-01

    In situations when there is unilateral ureteral obstruction, the contralateral kidney retains its normal function. In rare instances however, it has been reported that unilateral ureteral obstruction can lead to reflex anuria (RA) and acute renal failure (ARF). Even more unusually, RA with ARF can occur without organic obstruction due to ureteric manipulation during pelvic surgery. We report a 78- year-old woman, who underwent hysterectomy because of endometrial carcinoma. She developed ARF evidenced by anuria of 120-hours duration, and gradual rise of serum creatinine levels to 11.8 mg/dL on the fifth day after hysterectomy. Ultrasound study of the urinary tract revealed bilateral moderate hydronephrosis. Detailed evaluation did not reveal any organic obstruction. She was managed with hemodialysis, control of hypertension and correction of fluid and electrolyte imbalances. By the sixth day, diuresis was established, and the blood urea and serum creatinine levels decreased to normal by the sixteenth day. The patient was finally discharged on the eighteenth day. Our case suggests that urologists and nephrologists should consider RA as one of the causes of anuria and ARF.

  18. Blink reflexes in patients with atypical odontalgia.

    Science.gov (United States)

    Baad-Hansen, Lene; List, Thomas; Jensen, Troels Staehelin; Leijon, Göran; Svensson, Peter

    2005-01-01

    To use the human blink reflex (BR) to explore possible neuropathic pain mechanisms in patients with atypical odontalgia (AO). In 13 AO patients, the BR was elicited using a concentric electrode and recorded bilaterally with surface electromyographic (EMG) electrodes on both orbicularis oculi muscles. Electrical stimuli were applied to the skin above branches of the V1, V2, and V3 nerves and to the V branch contralateral to the painful branch. Sensory and pain thresholds were determined. The BR examination of the painful V branch was repeated during a capsaicin pain-provocation test. The data were analyzed with nonparametric statistics. The BR responses (R2 and R3) evoked by stimulation of V3 were significantly smaller than the BR responses evoked by stimulation of V1 and V2 (P .569), and the BR (R2 and R3) was not significantly modulated by experimental pain (P > .080). The sensory thresholds were significantly lower on the painful side compared to the nonpainful side (P = .014). The pain thresholds were not different between sides (P > .910). No major differences between the V nociceptive pathways on the right and left sides were found in a relatively small group of AO patients. Future studies that compare BRs in AO patients and healthy volunteers are needed to provide further knowledge on the pain mechanisms in AO.

  19. Cough reflex hypersensitivity: A role for neurotrophins.

    Science.gov (United States)

    El-Hashim, Ahmed Z; Jaffal, Sahar M

    2017-03-01

    Cough is one of the most common complaints for which sufferers seek medical assistance. However, currently available drugs are not very effective in treating cough, particularly that which follows an upper respiratory tract infection. Nonetheless, there has been a significant increase in our understanding of the mechanisms and pathways of the defensive cough as well as the hypersensitive/pathophysiological cough, both at airway and central nervous system (CNS) levels. Numerous molecules and signaling pathways have been identified as potential targets for antitussive drugs, including neurotrophins (NTs). NTs belong to a family of trophic factors and are critical for the development and maintenance of neurons in the central and peripheral nervous system including sympathetic efferents, sensory neuron afferents, and immune cells. Nerve growth factor (NGF) was the first member of the NT family to be discovered, with wide ranging actions associated with synapse formation, survival, proliferation, apoptosis, axonal and dendritic outgrowth, expression and activity of functionally important proteins such as ion channels, receptors, and neurotransmitters. In addition, NGF has been implicated in several disease states particularly neuropathic pain and most recently in the sensitization of the cough reflex. This review will briefly address the peripheral and central sensitization mechanisms of airway neurons and will then focus on NGF signaling and its role in cough hypersensitivity.

  20. Reflex anuria: a rare cause of acute kidney injury

    OpenAIRE

    Dhakarwal, Pradeep; Adediran, Samuel

    2014-01-01

    Background: Acute Kidney Injury results from pre renal, post renal or intrinsic renal causes. Reflex anuria is a very rare cause of renal impairment which happens due to irritation or trauma to one kidney or ureter, or severely painful stimuli to other nearby organs.Case Presentation: Here we present a case of acute kidney injury secondary to reflex anuria in a patient who underwent extensive gynecological surgery along with ureteral manipulation which recovered spontaneously.Conclusion: Refl...

  1. A tapetal-like fundus reflex in a healthy male

    DEFF Research Database (Denmark)

    Schatz, Patrik; Bregnhøj, Jesper; Arvidsson, Henrik Sven

    2012-01-01

    To report on the retinal function and structure in a 37-year-old male who presented with a tapetal-like reflex (TLR) indistinguishable from that seen in female carriers of X-linked retinitis pigmentosa (XLRP).......To report on the retinal function and structure in a 37-year-old male who presented with a tapetal-like reflex (TLR) indistinguishable from that seen in female carriers of X-linked retinitis pigmentosa (XLRP)....

  2. Mechanical Characteristics of Reflex Durign Upright Posture in Paralyzed Subjects

    Science.gov (United States)

    Kim, Yongchul; Youm, Youngil; Lee, Bumsuk; Kim, Youngho; Choi, Hyeonki

    The characteristics of flexor reflexes have been investigated in the previous studies with human subjects who were seated or supine position. However, researchers did not describe how the spinal circuits are used in different hip angles for paralyzed subjects, such as the standing position with walker or cane. In upright posture the compatibility between a flexor reflex of leg and body balance is a special problem for lower limb injured subjects. Therefore, the purpose of this study was to investigate the effects of hip angle change on the flexor reflex evoked in standing paralyzed subjects supported by walker. In this study, six spinal cord injured and four stroke subjects were recruited through the inpatient physical therapy clinics of Korea national rehabilitation hospital. A single axis electronic goniometer was mounted on the lateral side of the hip joint of the impaired limb to record movements in the sagittal plane at this joint. The electronic goniometer was connected to a data acquisition system, through amplifiers to a computer. Since subject' posture influenced characteristics of the flexion reflex response, the subjects were supported in an upright posture by the help of parallelogram walder. Two series of tests were performed on each leg. The first series of the tests investigated the influence of hip angle during stationary standing posture on flexion reflex response. The hip angle was adjusted by the foot plate. The second examined the effect of the voluntary action of subject on swing motion during the gait. The electrically induced flexion reflex simultaneously produced the flexion of the hip, knee and dorsiflexion of the ankle enabling the swing phase of walking. Form the experimental results we observed that the reflex response of hip joint was largerwith the hip in the extended position than in the flexed position during standing posture. Under voluntary movement on flexion reflex during gaint, the peak hip angle induced by stimulation was

  3. Embodied Reflexivity in Qualitative Analysis: A Role for Selfies

    Directory of Open Access Journals (Sweden)

    Martina Kelly

    2017-05-01

    Full Text Available This article introduces a case study on the use of selfies as a means to support embodied reflexivity in phenomenological research. There is a recognized need to make reflexive practice in qualitative health research more transparent. There is also a move towards an embodied type of reflexivity whereby researchers pay attention to their physical reactions as part of the research process. Being reflexive is especially challenging when researchers work in teams rather than as individuals, and when researchers and participants do not meet because data collection and analysis are separate from one another. We used FINLAY's (2005 model of reflexive embodied empathy to explain how taking selfies allowed an international team of researchers to engage reflexively with a participant when their primary access to her lifeworld was an interview transcript. Key concepts from FOUCAULT's (1988 theory of technologies of self, critical self-awareness and self-stylization, shed light on this phenomenon. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1702124

  4. HPLC analysis of closed, open, and reflex eye tear proteins

    Directory of Open Access Journals (Sweden)

    Sitaramamma T

    1998-01-01

    Full Text Available Changes in the closed, open and reflex eye tear proteins of normal subjects were compared and analysed. Tear proteins were resolved by high-performance liquid chromatography (HPLC utilising both gel filtration (P-300 SW and reverse-phase (C-18 columns and the HPLC fractions were further analysed by sodium dodecyl sulphate - polyacrylamide gel electrophoresis (SDS-PAGE under reducing and non-reducing conditions. The protein composition of the closed-eye tear was significantly different from that of the open and reflex-eye tear. Secretory IgA (sIgA was the predominant protein in closed eye tears constituting 49% of the total protein compared to 11% in reflex tears, whereas lysozyme was the predominant protein (53% in reflex tears. Levels of lactoferrin, lipocalin and lysozyme were relatively constant in both open and reflex tears. HPLC profiles of the closed-eye tears, upon continuous stimulation of lacrimal glands indicated that sIgA was significantly reduced whereas lactoferrin, lipocalin, and lysozyme were significantly increased. These results indicate that the tear composition upon waking attains that of the open eye within 4 to 5 minutes, and upon continuous stimulation this reflects the reflex-eye tear composition. It also indicates that mechanisms responsible for changes in concentration of constitutive and regulated tear protein with stimulus can be studied successfully using non-invasive methods to collect human tears.

  5. HPLC analysis of closed, open, and reflex eye tear proteins.

    Science.gov (United States)

    Sitaramamma, T; Shivaji, S; Rao, G N

    1998-12-01

    Changes in the closed, open and reflex eye tear proteins of normal subjects were compared and analysed. Tear proteins were resolved by high-performance liquid chromatography (HPLC) utilising both gel filtration (P-300 SW) and reverse-phase (C-18) columns and the HPLC fractions were further analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing and non-reducing conditions. The protein composition of the closed-eye tear was significantly different from that of the open and reflex-eye tear. Secretory IgA (sIgA) was the predominant protein in closed eye tears constituting 49% of the total protein compared to 11% in reflex tears, whereas lysozyme was the predominant protein (53%) in reflex tears. Levels of lactoferrin, lipocalin and lysozyme were relatively constant in both open and reflex tears. HPLC profiles of the closed-eye tears, upon continuous stimulation of lacrimal glands indicated that sIgA was significantly reduced whereas lactoferrin, lipocalin, and lysozyme were significantly increased. These results indicate that the tear composition upon waking attains that of the open eye within 4 to 5 minutes, and upon continuous stimulation this reflects the reflex-eye tear composition. It also indicates that mechanisms responsible for changes in concentration of constitutive and regulated tear protein with stimulus can be studied successfully using non-invasive methods to collect human tears.

  6. Disturbance Compensating Control of a Biped Walking Machine Based on Reflex Motions

    Science.gov (United States)

    Funabashi, Hiroaki; Takeda, Yukio; Itoh, Shigenari; Higuchi, Masaru

    A control system that utilizes the concept of reflex control in animals is proposed for a biped walking machine with consideration of compensation of external disturbances. A walking machine was modeled as a sequential machine, and a series of single-reflex motions was synthesized for it. A hierarchical three-level control system was constructed. As disturbances, two types of external forces were considered: “impulsive” force with a large magnitude and short action-time and “continuous” force with a small magnitude and long action time. Appropriate state variables for rapid and reliable sensing of each disturbance were investigated and the thresholds of their values used as the triggers for changing the gait from a periodic gait to a disturbance compensation one were determined. Motions of disturbance compensation gaits were determined by combining some single-reflex motions. A control system for an experimental biped walking machine whose mass is 18kg, total height is 0.66m, step length is 0.25m and walking cycle is 133 steps/min was constructed and tested. The proposed control system enabled the walking machine to successfully avoid tumbling when it was subjected to the two external forces and return to a periodic gait.

  7. Retrieval Interference in Syntactic Processing: The Case of Reflexive Binding in English.

    Science.gov (United States)

    Patil, Umesh; Vasishth, Shravan; Lewis, Richard L

    2016-01-01

    It has been proposed that in online sentence comprehension the dependency between a reflexive pronoun such as himself/herself and its antecedent is resolved using exclusively syntactic constraints. Under this strictly syntactic search account, Principle A of the binding theory-which requires that the antecedent c-command the reflexive within the same clause that the reflexive occurs in-constrains the parser's search for an antecedent. The parser thus ignores candidate antecedents that might match agreement features of the reflexive (e.g., gender) but are ineligible as potential antecedents because they are in structurally illicit positions. An alternative possibility accords no special status to structural constraints: in addition to using Principle A, the parser also uses non-structural cues such as gender to access the antecedent. According to cue-based retrieval theories of memory (e.g., Lewis and Vasishth, 2005), the use of non-structural cues should result in increased retrieval times and occasional errors when candidates partially match the cues, even if the candidates are in structurally illicit positions. In this paper, we first show how the retrieval processes that underlie the reflexive binding are naturally realized in the Lewis and Vasishth (2005) model. We present the predictions of the model under the assumption that both structural and non-structural cues are used during retrieval, and provide a critical analysis of previous empirical studies that failed to find evidence for the use of non-structural cues, suggesting that these failures may be Type II errors. We use this analysis and the results of further modeling to motivate a new empirical design that we use in an eye tracking study. The results of this study confirm the key predictions of the model concerning the use of non-structural cues, and are inconsistent with the strictly syntactic search account. These results present a challenge for theories advocating the infallibility of the human

  8. CORRECTION OF GLOBAL AND REFLEX RADIATION VALUES MEASURED ABOVE THE LAKE BALATON

    Directory of Open Access Journals (Sweden)

    Laszlo Menyhart

    2014-03-01

    Full Text Available Albedo measurements have been carried out since 2007 above the Lake Balaton near Keszthely and Siofok. It turned out that a systematic offset error was superposed to both the global and the reflex radiation. The value of this systematic error was approximately constant per pyranometer within a year but on the other hand it varied from year to year and from pyranometer to pyranometer. In this paper the values of this systematic errors were determined with two different methods. The difference between the values measured at night-time and the intrinsic thermal offset error of pyranometers were examined with both methods. The base of the first method is the empirical observation, that the values measured at night-time by a global radiometer are typically negative whereas by a reflex radiometer are typically positive. The substance of the second method is utilizing the air temperature measured within 1 as well as 5 hours before the radiation measuring to +select the fully overcast nights, when the thermal offset error of the global radiometer is zero. In addition, the cases where the thermal offset error of the reflex radiometer is zero were selected on the basis of the difference between water and air temperature. When the thermal offset error is zero the measured value is equal to the systematic error. Comparing the results of the two methods showed that the systematic error of the global radiometer were determined with uncertainty of 1 Wm–2, whereas that of the reflex radiometer with uncertainty of 2 Wm–2. The calibration constants were recalculated from the values being in the calibration reports taking the systematic errors into account.

  9. Meta-analysis of stem cell transplantation for reflex hypersensitivity after spinal cord injury.

    Science.gov (United States)

    Chen, Xuemei; Xue, Bohan; Li, Yuping; Song, Chunhua; Jia, Peijun; Ren, Xiuhua; Zang, Weidong; Wang, Jian

    2017-11-05

    Stem cells have been used in novel therapeutic strategies for spinal cord injury (SCI), but the effect of stem cell transplantation on neuropathic pain after SCI is unclear. The current meta-analysis evaluates the effects of stem cell transplantation on neuropathic pain after SCI. We first conducted online searches of PubMed, Web of Science, China Academic Journals Full-text Database, and Wanfang Data for randomized controlled trials that compared stem cell transplantation and vehicle treatments in rodent models of neuropathic pain after SCI. Quality assessment was performed using Cochrane Reviewer's Handbook 5.1.0, and meta-analysis was conducted with RevMan 5.3. Then, we developed a rat model of SCI and transplanted bone marrow mesenchymal stem cells to verify meta-analysis results. Twelve randomized, controlled trials (n=354 total animals) were included in our meta-analysis and divided by subgroups, including species, timing of behavioral measurements, and transplantation time after SCI. Subgroup analysis of these 12 studies indicated that stem cell-treated animals had a higher mechanical reflex threshold than vehicle groups, with a significant difference in both rats and mice. The thermal withdrawal latency showed the same results in mouse subgroups, but not in rat subgroups. In addition, mesenchymal stem cell transplantation was an effective treatment for mechanical, but not thermal reflex hypersensitivity relief in rats. Transplantation showed a positive effect when carried out at 3 or 7days post-SCI. Stem cell transplantation alleviates mechanical reflex hypersensitivity in rats and mice and thermal reflex hypersensitivity in mice after SCI. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. A method of reflexive balancing in a pragmatic, interdisciplinary and reflexive bioethics.

    Science.gov (United States)

    Ives, Jonathan

    2014-07-01

    In recent years there has been a wealth of literature arguing the need for empirical and interdisciplinary approaches to bioethics, based on the premise that an empirically informed ethical analysis is more grounded, contextually sensitive and therefore more relevant to clinical practice than an 'abstract' philosophical analysis. Bioethics has (arguably) always been an interdisciplinary field, and the rise of 'empirical' (bio)ethics need not be seen as an attempt to give a new name to the longstanding practice of interdisciplinary collaboration, but can perhaps best be understood as a substantive attempt to engage with the nature of that interdisciplinarity and to articulate the relationship between the many different disciplines (some of them empirical) that contribute to the field. It can also be described as an endeavour to explain how different disciplinary approaches can be integrated to effectively answer normative questions in bioethics, and fundamental to that endeavour is the need to think about how a robust methodology can be articulated that successfully marries apparently divergent epistemological and metaethical perspectives with method. This paper proposes 'Reflexive Bioethics' (RB) as a methodology for interdisciplinary and empirical bioethics, which utilizes a method of 'Reflexive Balancing' (RBL). RBL has been developed in response to criticisms of various forms of reflective equilibrium, and is built upon a pragmatic characterization of Bioethics and a 'quasi-moral foundationalism', which allows RBL to avoid some of the difficulties associated with RE and yet retain the flexible egalitarianism that makes it intuitively appealing to many. © 2013 John Wiley & Sons Ltd.

  11. Choice reaction times for human head rotations are shortened by startling acoustic stimuli, irrespective of stimulus direction

    NARCIS (Netherlands)

    Oude Nijhuis, L.B.; Janssen, L.; Bloem, B.R.; Dijk, J.G. van; Gielen, C.C.A.M.; Borm, G.F.; Overeem, S.

    2007-01-01

    Auditory startle reflexes can accelerate simple voluntary reaction times (StartReact effect). To investigate the role of startle reflexes on more complex motor behaviour we formulated two questions: (1) can auditory startle reflexes shorten choice reaction times?; (2) is the StartReact effect

  12. A reflective account on becoming reflexive: the 7 Cs of caring conversations as a framework for reflexive questioning

    Directory of Open Access Journals (Sweden)

    Edel Roddy

    2016-05-01

    Full Text Available Context: Some uncertainty surrounds both the definition and the application of reflexivity in participatory research and practice development. There is scope for further exploration of what reflexivity might look like in practice, and how the researcher/practice developer and participants might be involved. This paper does this in the context of a study that is using appreciative inquiry to explore the experience of inspection in care homes. Aims: I will explore my personal journey into the use of a relational constructionist approach to reflexivity and suggest that the 7 Cs of caring conversations provide a useful framework to inform reflexive practice. The 7 Cs will be used as a framework for the telling of this story. Implications for practice: Relational reflexivity has the potential to create the space for all those involved in research/practice development initiatives to voice their thoughts and feelings about the initiative and their involvement in it The 7 Cs of caring conversations can provide a framework for developing questions that may serve as a starting point for cultivating reflexive practice

  13. Reflex anuria from unilateral ureteral obstruction.

    Science.gov (United States)

    Catalano, C; Comuzzi, E; Davì, L; Fabbian, F

    2002-03-01

    Renal function is usually normal or only marginally affected in patients with unilateral ureteral obstruction due to the vicarious function of the contralateral kidney. Few reports exist in which unilateral renal obstruction is associated with anuria (reflex anuria, RA) and acute renal failure. We report the clinical case of a female patient who was referred to the emergency department due to anuria of 72 h duration and acute renal failure (serum creatinine 9 mg/dl) associated with several episodes of violent right flank pain with hematuria following extracorporeal shock wave lithotripsy (ESWL). A few weeks before ESWL, urography showed a 2-cm stone located in the right pelvis whilst the left kidney was functionally normal. On admission, renal ultrasound documented a normal left kidney, whilst the right pelvis was hydronephrotic and there were two indwelling stones at the right pyeloureteral junction. After the patient passed a urinary stone, diuresis restarted and acute renal failure was resolved. Thereafter, urography confirmed that the left kidney, the left ureter and bladder were functionally and morphologically normal. RA with acute renal failure has been so scarcely documented that it is considered to be legend by many clinicians. Major textbooks do not discuss RA with acute renal failure. Vascular or ureteral spasm related in part to a peculiar hyperexcitability of the autonomic nervous system may explain RA. We suggest that nephrologists should always consider RA when evaluating acute renal failure. On the other hand, RA might be relatively common and we cannot rule out that only the most severe and/or better-documented cases have been reported in the medical literature. Copyright 2002 S. Karger AG, Basel

  14. Reflex epilepsies: experience in Sri Lanka.

    Science.gov (United States)

    Senanayake, N

    1994-06-01

    Reflex epilepsy (RE) is characterised by seizures that are regularly elicited by some specific stimulus or event mediated by neural pathways. In a prospective study of 1287 epileptic patients seen at Peradeniya, 223 (17.3%) were found to have RE, eating being the commonest stimulus (191 patients, 85.7%). Photosensitive epilepsy (PSE) was relatively rare. Intermittent photic stimulation on 874 unselected epileptic patients produced a positive photoconvulsive response in 60 (6.9%). None had photosensitive seizures, but 3 had a higher frequency of seizures while watching television. Eating epilepsy (EE) had the highest prevalence at Peradeniya (148/1000 epileptic patients). This group was male predominant, and the onset of epilepsy in most cases was in the second decade. The majority experienced partial complex seizures. Repetitive and chronic stimulation of the amygdala during eating is suggested as the mechanism underlying EE. Twenty-one patients had seizures evoked by calculation, problem solving or spatial tasks. Juvenile myoclonic epilepsy was the commonest form of seizure disorder in them. Although PSE itself is rare, self-induced epilepsy (SIE) was common. There were 8 patients who self-induced seizures. The majority were photosensitive and they induced seizures by gazing at the sun and waving a hand in front of the eyes. In the management of REs, clobazam produced impressive results. As for possible seizure-inhibitory mechanisms, our studies on a "Sathi" mediator showed definite EEG changes during mediation. Can mediation increase the seizure-threshold and abort or prevent the propagation of the epileptic discharge? The answer, apart from its possible therapeutic applications, may provide insight into the mechanisms of seizure generation.

  15. Spinal reflexes in ankle flexor and extensor muscles after chronic central nervous system lesions and functional electrical stimulation.

    Science.gov (United States)

    Thompson, Aiko K; Estabrooks, Kristen L; Chong, Suling; Stein, Richard B

    2009-02-01

    Spinal reciprocal inhibitory and excitatory reflexes of ankle extensor and flexor muscles were investigated in ambulatory participants with chronic central nervous system (CNS) lesions causing foot drop as a function of time after lesion and stimulator use. Thirty-nine participants with progressive (eg, secondary progressive MS) and 36 with generally nonprogressive (eg, stroke) conditions were studied. The tibialis anterior (TA) and soleus maximum H-reflex/M-wave (Hmax/Mmax) ratios and maximum voluntary contractions (MVC) were measured and compared with those in age-matched control participants. Reciprocal inhibition was measured as a depression of the ongoing electromyographic (EMG) activity produced by antagonist muscle-nerve stimulation. Participants with CNS lesions had significantly higher soleus Hmax/Mmax ratios than control participants, and reduced voluntary modulation of the reflexes occurred in both muscles. Reciprocal inhibition of soleus from common peroneal (CP) nerve stimulation was not significantly different from controls in either group. Inhibition of the TA by tibial nerve stimulation decreased and was eventually replaced by excitation in participants with nonprogressive disorders. No significant change occurred in progressive disorders. Use of a foot drop stimulator increased the TA, but not the soleus MVC overall. H-reflexes only showed small changes. Reciprocal inhibition of the TA increased considerably, while that of the soleus muscle decreased toward control values. Disorders that produce foot drop also produce reflex changes, some of which only develop over a period of years or even decades. Regular use of a foot drop stimulator strengthens voluntary pathways and changes some reflexes toward control values. Thus, stimulators may provide multiple benefits to people with foot drop.

  16. Measurement of post-stroke spasticity based on tonic stretch reflex threshold: implications of stretch velocity for clinical practice.

    Science.gov (United States)

    Marques, Isabela Alves; Silva, Maristella Borges; Silva, Andrei Nakagawa; Luiz, Luiza Maire David; Soares, Alcimar Barbosa; Naves, Eduardo Lázaro Martins

    2017-10-02

    The most commonly used method for the clinical evaluation of spasticity is the modified Ashworth scale (MAS), which is subjective. In this regard, the spasticity assessment through the tonic stretch reflex threshold, which is an objective method, has emerged as an alternative. It is based on the value of the dynamic stretch reflex threshold, which is measured at different stretch velocities. However, by this definition, it is not possible to define the speed at which passive stretches should be performed during evaluation. This study aimed to evaluate whether the speed-variation sequence used to acquire the dynamic stretch reflex threshold influences the tonic stretch reflex threshold (TSRT) and, consequently, the estimation of spasticity by this method. Three forms of stretching-variation speed were adopted, i.e., increasing, decreasing, and randomised. The study was performed using 10 post-stroke patients. The results showed that the stretch protocols were not all the same and that the method of increasing was most suitable for performing manual passive stretches to evaluate TSRT in these patients. Another analysis was the correlation between MAS and tonic stretch reflex threshold; a weak correlation was observed between the increasing and decreasing methods, and moderate correlation was observed between the random methods. Implications for Rehabilitation We demonstrated that the protocol of execution of passive stretches influences in the measurement of the tonic stretch reflex threshold (TSRT). We recommend the method of increasing velocity for performing manual passive stretches. We also build software with a reliable biological data acquisition system, which makes acquisition and processing of data in real time. In this way, the TSRT is a promising quantitative measure to assess post-stroke spasticity, calculated automatically. We also we provided the use of portable instruments to facilitate the assessment of spasticity in clinical practice.

  17. [Reflex sympathetic dystrophy secondary to piriformis syndrome: a case report].

    Science.gov (United States)

    Akçali, Didem; Taş, Ayça; Cizmeci, Pelin; Oktar, Suna; Zinnuroğlu, Murat; Arslan, Emre; Köseoğlu, Hüseyin; Babacan, Avni

    2009-04-01

    Piriformis syndrome is a rare cause of hip and foot pain which may be due to sciatic nerve irritation because of anatomic abnormalities of sciatic nerve and piriformis muscle or herniated disc, facet syndrome, trochanteric bursit, sacroiliac joint dysfunction, endometriosis and other conditions where sciatic nerve is irritated. There has been no reflex sympathetic dystrophy (RSD) case presented due to piriformis syndrome before. A sixty-two-year-old female patient had right foot and hip pain (VNS: 8), redness and swelling in the foot since 15 days. Her history revealed long walks and travelling 3 weeks ago and sitting on the foot for a long time for a couple of days. Physical examination revealed painful hip movement, positive straight leg rise. Erythema and hyperalgesia was present in dorsum of the right foot. Right foot dorsiflexion was weak and hyperesthesia was found in right L4-5 dermatome. Medical treatment and ultrasound treatment to piriformis muscle was not effective. The patient was injected 40 mg triamcinolon and local anesthetic in right piriformis muscle under floroscopy by diagnosis of piriformis syndrome, neuropathic pain and RSD. Pain and hyperalgesia resolved and motor weakness was better. During follow-up right foot redness resolved and pain decreased (VNS: 1). In this case report, there was vascular, muscle and skeletal signs supporting RSD, which shows us the therapoetic effect of diagnostic piriformis injection. The patient history, physical examination and diagnostic tests were evaluated by a multidisciplinary team which contributed to the treatment.

  18. Primate translational vestibuloocular reflexes. IV. Changes after unilateral labyrinthectomy

    Science.gov (United States)

    Angelaki, D. E.; Newlands, S. D.; Dickman, J. D.

    2000-01-01

    The effects of unilateral labyrinthectomy on the properties of the translational vestibuloocular reflexes (trVORs) were investigated in rhesus monkeys trained to fixate near targets. Translational motion stimuli consisted of either steady-state lateral and fore-aft sinusoidal oscillations or short-lasting transient displacements. During small-amplitude, steady-state sinusoidal lateral oscillations, a small decrease in the horizontal trVOR sensitivity and its dependence on viewing distance was observed during the first week after labyrinthectomy. These deficits gradually recovered over time. In addition, the vertical response component increased, causing a tilt of the eye velocity vector toward the lesioned side. During large, transient lateral displacements, the deficits were larger and longer lasting. Responses after labyrinthectomy were asymmetric, with eye velocity during movements toward the side of the lesion being more compromised. The most profound effect of the lesions was observed during fore-aft motion. Whereas responses were kinematically appropriate for fixation away from the side of the lesion (e.g., to the left after right labyrinthectomy), horizontal responses were anticompensatory during fixation at targets located ipsilateral to the side of the lesion (e.g., for targets to the right after right labyrinthectomy). This deficit showed little recovery during the 3-mo post-labyrinthectomy testing period. These results suggest that inputs from both labyrinths are important for the proper function of the trVORs, although the details of how bilateral signals are processed and integrated remain unknown.

  19. Exercise pressor reflex function is altered in spontaneously hypertensive rats.

    Science.gov (United States)

    Smith, Scott A; Williams, Maurice A; Leal, Anna K; Mitchell, Jere H; Garry, Mary G

    2006-12-15

    In hypertension, exercise elicits excessive elevations in mean arterial pressure (MAP) and heart rate (HR) increasing the risk for adverse cardiac events and stroke during physical activity. The exercise pressor reflex (a neural drive originating in skeletal muscle), central command (a neural drive originating in cortical brain centres) and the tonically active arterial baroreflex contribute importantly to cardiovascular control during exercise. Each of these inputs potentially mediates the heightened cardiovascular response to physical activity in hypertension. However, given that exercise pressor reflex overactivity is known to elicit enhanced circulatory responses to exercise in disease states closely related to hypertension (e.g. heart failure), we tested the hypothesis that the exaggerated cardiovascular response to exercise in hypertension is mediated by an overactive exercise pressor reflex. To test this hypothesis, we used a rat model of exercise recently developed in our laboratory that selectively stimulates the exercise pressor reflex independent of central command and/or the arterial baroreflex. Activation of the exercise pressor reflex during electrically induced static muscle contraction in the absence of input from central command resulted in significantly larger increases in MAP and HR in male spontaneously hypertensive rats as compared to normotensive Wistar-Kyoto rats over a wide range of exercise intensities. Similar findings were obtained in animals in which input from both central command and the arterial baroreflex were eliminated. These findings suggest that the enhanced cardiovascular response to exercise in hypertension is mediated by an overactive exercise pressor reflex. Potentially, effective treatment of exercise pressor reflex dysfunction may reduce the cardiovascular risks associated with exercise in hypertension.

  20. Trigeminal cardiac reflex and cerebral blood flow regulation

    Directory of Open Access Journals (Sweden)

    Dominga Lapi

    2016-10-01

    Full Text Available The stimulation of some facial regions is known to trigger the trigemino-cardiac reflex: the main stimulus is represented by the contact of the face with water. This phenomenon called diving reflex induces a set of reactions in the cardiovascular and respiratory systems occurring in all mammals, especially marine (whales, seals. During the immersion of the face in the water, the main responses are aimed at reducing the oxygen consumption of the organism. Accordingly reduction in heart rate, peripheral vasoconstriction, blood pooling in certain organs, especially the heart and brain, and an increase in blood pressure have been reported. Moreover, the speed and intensity of the reflex is inversely proportional to the temperature of the water: more cold the water, more reactions as described are strong. In the case of deep diving an additional effect, such as blood deviation, has been reported: the blood is requested within the lungs, to compensate for the increase in the external pressure, preventing them from collapsing.The trigeminal-cardiac reflex is not just confined to the diving reflex; recently it has been shown that a brief proprioceptive stimulation (10 min by jaw extension in rats produces interesting effects both at systemic and cerebral level, reducing the arterial blood pressure and vasodilating the pial arterioles. The arteriolar dilation is associated with rhythmic diameter changes characterized by an increase in the endothelial activity. Fascinating the stimulation of trigeminal nerve is able to activated the nitric oxide release by vascular endothelial. Therefore the aim of this review was to highlight the effects due to trigeminal cardiac reflex induced by a simple mandibular extension, because produced opposite effects compared to those elicited by the diving reflex as it induces hypotension and modulation of cerebral arteriolar tone.

  1. OPERANT CONDITIONING OF SPINAL REFLEXES:FROM BASIC SCIENCE TO CLINICAL THERAPY

    Directory of Open Access Journals (Sweden)

    Aiko K. Thompson

    2014-03-01

    Full Text Available New appreciation of the adaptive capabilities of the nervous system, recent recognition that most spinal cord injuries are incomplete, and progress in enabling regeneration are generating growing interest in novel rehabilitation therapies. Here we review the 35-year evolution of one promising new approach, operant conditioning of spinal reflexes. This work began in the late 1970’s as basic science; its purpose was to develop and exploit a uniquely accessible model for studying the acquisition and maintenance of a simple behavior in the mammalian CNS. The model was developed first in monkeys and then in rats, mice, and humans. Studies with it showed that the ostensibly simple behavior (i.e., a larger or smaller reflex rests on a complex hierarchy of brain and spinal cord plasticity; and current investigations are delineating this plasticity and its interactions with the plasticity that supports other behaviors. In the last decade, the possible therapeutic uses of reflex conditioning have come under study, first in rats and then in humans. The initial results are very exciting, and they are spurring further studies. At the same time, the original basic science purpose and the new clinical purpose are enabling and illuminating each other in unexpected ways. The long course and current state of this work illustrate the practical importance of basic research and the valuable synergy that can develop between basic science questions and clinical needs.

  2. Operant conditioning of spinal reflexes: from basic science to clinical therapy

    Science.gov (United States)

    Thompson, Aiko K.; Wolpaw, Jonathan R.

    2014-01-01

    New appreciation of the adaptive capabilities of the nervous system, recent recognition that most spinal cord injuries are incomplete, and progress in enabling regeneration are generating growing interest in novel rehabilitation therapies. Here we review the 35-year evolution of one promising new approach, operant conditioning of spinal reflexes. This work began in the late 1970’s as basic science; its purpose was to develop and exploit a uniquely accessible model for studying the acquisition and maintenance of a simple behavior in the mammalian central nervous system (CNS). The model was developed first in monkeys and then in rats, mice, and humans. Studies with it showed that the ostensibly simple behavior (i.e., a larger or smaller reflex) rests on a complex hierarchy of brain and spinal cord plasticity; and current investigations are delineating this plasticity and its interactions with the plasticity that supports other behaviors. In the last decade, the possible therapeutic uses of reflex conditioning have come under study, first in rats and then in humans. The initial results are very exciting, and they are spurring further studies. At the same time, the original basic science purpose and the new clinical purpose are enabling and illuminating each other in unexpected ways. The long course and current state of this work illustrate the practical importance of basic research and the valuable synergy that can develop between basic science questions and clinical needs. PMID:24672441

  3. Abnormal cortical excitability with preserved brainstem and spinal reflexes in sialidosis type I.

    Science.gov (United States)

    Huang, Ying-Zu; Lai, Szu-Chia; Lu, Chin-Song; Weng, Yi-Hsin; Chuang, Wen-Li; Chen, Rou-Shayn

    2008-05-01

    To examine neurophysiological evidence of functional involvement of the brainstem and spinal cord and motor cortical excitability in sialidosis type I, a rare inherited neurodegenerative disorder caused by mutations in the NEU1 gene. We investigated particular pathways in the brainstem, spinal cord and motor cortex in 12 genetically proven cases of sialidosis type I by assessing blink reflex recovery cycle (BR), spinal reciprocal inhibition (RI), input-output curves (I/O), short interval intracortical inhibition (SICI), intracortical facilitation (ICF) and silent period (SP). The BR and RI were normal. The slope of I/O was significantly increased, and SICI and the duration of SP were reduced in sialidosis patients. Despite reports of pathology involving brainstem and anterior horn neurones, there were no obvious abnormalities in spinal and brainstem reflexes in the present patients, suggesting that the major clinical effects may be caused by changes at a level above the brainstem. For the first time, the integrity of certain brainstem and spinal cord reflexes in addition to motor cortical facilitatory and inhibitory circuits has been assessed in genetically proven type I sialidosis. This provides new data to aid in understanding of the pathophysiology of motor system dysfunction in this condition.

  4. Intact Reflexive but Deficient Voluntary Social Orienting in Autism Spectrum Disorder

    Science.gov (United States)

    Kirchgessner, Megan A.; Chuang, Alice Z.; Patel, Saumil S.; Sereno, Anne B.

    2015-01-01

    Impairment in social interactions is a primary characteristic of people diagnosed with autism spectrum disorder (ASD). Although these individuals tend to orient less to naturalistic social cues than do typically developing (TD) individuals, laboratory experiments testing social orienting in ASD have been inconclusive, possibly because of a failure to fully isolate reflexive (stimulus-driven) and voluntary (goal-directed) social orienting processes. The purpose of the present study was to separately examine potential reflexive and/or voluntary social orienting differences in individuals with ASD relative to TD controls. Subjects (ages 7–14) with high-functioning ASD and a matched control group completed three gaze cueing tasks on an iPad in which individuals briefly saw a face with averted gaze followed by a target after a variable delay. Two tasks were 100% predictive with either all congruent (target appears in gaze direction) or all incongruent (target appears opposite from gaze direction) trials, respectively. Another task was non-predictive with these same trials (half congruent and half incongruent) intermixed randomly. Response times (RTs) to the target were used to calculate reflexive (incongruent condition RT—congruent condition RT) and voluntary (non-predictive condition RT—predictive condition RT) gaze cueing effects. Subjects also completed two additional non-social orienting tasks (ProPoint and AntiPoint). Subjects with ASD demonstrate intact reflexive but deficient voluntary gaze following. Similar results were found in a separate test of non-social orienting. This suggests problems with using social cues, but only in a goal-directed fashion, in our sample of high-functioning individuals with ASD. Such findings may not only explain inconclusive previous findings but more importantly be critical for understanding social dysfunctions in ASD and for developing future interventions. PMID:26648841

  5. Notes on Post-criticality: Towards an Architecture of Reflexive Modernisation

    Directory of Open Access Journals (Sweden)

    Robert Cowherd

    2014-07-01

    Full Text Available Since around 2002, the performance of critical theory in architecture and the humanities has itself undergone a critical re-evaluation. Authors representing divergent perspectives, from theory’s perennial naysayers to the standard bearers of critical theory themselves, have converged towards a similar conclusion: judged by outcomes, critical theory has proven ineffective at best, and arguably, corrosive to human progress. In architecture, the debate has revolved around the identification of a ‘critical architecture’ in education and production since the 1970s. In apparent rejection of the isolation and purity of critical architecture’s orthodoxy, Rem Koolhaas and others have chosen engagement with the forces (and commissions of late capitalism to which the term ‘post-criticality’ has been applied.Beyond the confining dichotomies of the post-criticality debate is a perspective offered by sociologists Ulrich Beck, Scott Lash and Anthony Giddens on what they have called a ‘second modernity’ or ‘reflexive modernisation’. This literature re-contextualises the modern-postmodern pairing within the larger trajectory of modernity and identifies a characteristic distinction from former modernities in the term ‘reflexivity’. Where high modernism pursued utopian ideals of pure form and functional simplicity, reflexive modernisation acknowledges contingency in human systems establishing feedback loops that trigger course corrections in the process of modernisation itself.
Operating against the ossifications of twentieth-century modernity, reflexivity opens prospects for a second modernisation characterised by a heightened capacity to deal with complexity and time. Speculative architectures of reflexive modernisation benefit from a re-engagement in real-world problems, particularly at the scale of the city. To what extent can considerations of political economy, culture, globalisation, and environmental crisis be translated into the

  6. Recovery of the vestibulocolic reflex after aminoglycoside ototoxicity in domestic chickens.

    Science.gov (United States)

    Goode, C T; Carey, J P; Fuchs, A F; Rubel, E W

    1999-03-01

    Avian auditory and vestibular hair cells regenerate after damage by ototoxic drugs, but until recently there was little evidence that regenerated vestibular hair cells function normally. In an earlier study we showed that the vestibuloocular reflex (VOR) is eliminated with aminoglycoside antibiotic treatment and recovers as hair cells regenerate. The VOR, which stabilizes the eye in the head, is an open-loop system that is thought to depend largely on regularly firing afferents. Recovery of the VOR is highly correlated with the regeneration of type I hair cells. In contrast, the vestibulocolic reflex (VCR), which stabilizes the head in space, is a closed-loop, negative-feedback system that seems to depend more on irregularly firing afferent input and is thought to be subserved by different circuitry than the VOR. We examined whether this different reflex also of vestibular origin would show similar recovery after hair cell regeneration. Lesions of the vestibular hair cells of 10-day-old chicks were created by a 5-day course of streptomycin sulfate. One day after completion of streptomycin treatment there was no measurable VCR gain, and total hair cell density was approximately 35% of that in untreated, age-matched controls. At 2 wk postlesion there was significant recovery of the VCR; at this time two subjects showed VCR gains within the range of control chicks. At 3 wk postlesion all subjects showed VCR gains and phase shifts within the normal range. These data show that the VCR recovers before the VOR. Unlike VOR gain, recovering VCR gain correlates equally well with the density of regenerating type I and type II vestibular hair cells, except at high frequencies. Several factors other than hair cell regeneration, such as length of stereocilia, reafferentation of hair cells, and compensation involving central neural pathways, may be involved in behavioral recovery. Our data suggest that one or more of these factors differentially affect the recovery of these two

  7. Intact reflexive but deficient voluntary social orienting in autism spectrum disorder

    Directory of Open Access Journals (Sweden)

    Megan Anne Kirchgessner

    2015-12-01

    Full Text Available Impairment in social interactions is a primary characteristic of people diagnosed with autism spectrum disorder (ASD. Although these individuals tend to orient less to naturalistic social cues than do typically developing (TD individuals, laboratory experiments testing social orienting in ASD have been inconclusive, possibly because of a failure to fully isolate reflexive (stimulus-driven and voluntary (goal-directed social orienting processes. The purpose of the present study was to separately examine potential reflexive and/or voluntary social orienting differences in individuals with ASD relative to TD controls. Subjects (ages 7-14 with high-functioning ASD and a matched control group completed three gaze cueing tasks on an iPad in which individuals briefly saw a face with averted gaze followed by a target after a variable delay. Two tasks were 100% predictive with either all congruent (target appears in gaze direction or all incongruent (target appears opposite from gaze direction trials, respectively. Another task was non-predictive with these same trials (half congruent and half incongruent intermixed randomly. Response times (RTs to the target were used to calculate reflexive (incongruent condition RT – congruent condition RT and voluntary (non-predictive condition RT – predictive condition RT gaze cueing effects. Subjects also completed two additional non-social orienting tasks (ProPoint and AntiPoint. Subjects with ASD demonstrate intact reflexive but deficient voluntary gaze following. Similar results were found in a separate test of non-social orienting. This suggests problems with using social cues, but only in a goal-directed fashion, in our sample of high-functioning individuals with ASD. Such findings may not only explain inconclusive previous findings but more importantly be critical for understanding social dysfunctions in ASD and for developing future interventions.

  8. A comprehensive gaze stabilization controller based on cerebellar internal models

    DEFF Research Database (Denmark)

    Vannucci, Lorenzo; Falotico, Egidio; Tolu, Silvia

    2017-01-01

    based on the coordination of VCR and VOR and OKR. The model, inspired by neuroscientific cerebellar theories, is provided with learning and adaptation capabilities based on internal models. We present the results for the gaze stabilization model on three sets of experiments conducted on the SABIAN robot......Gaze stabilization is essential for clear vision; it is the combined effect of two reflexes relying on vestibular inputs: the vestibulocollic reflex (VCR), which stabilizes the head in space and the vestibulo-ocular reflex (VOR), which stabilizes the visual axis to minimize retinal image motion...... and on the iCub simulator, validating the robustness of the proposed control method. The first set of experiments focused on the controller response to a set of disturbance frequencies along the vertical plane. The second shows the performances of the system under three-dimensional disturbances. The last set...

  9. Physiological principles of vestibular function on earth and in space

    Science.gov (United States)

    Minor, L. B.

    1998-01-01

    Physiological mechanisms underlying vestibular function have important implications for our ability to understand, predict, and modify balance processes during and after spaceflight. The microgravity environment of space provides many unique opportunities for studying the effects of changes in gravitoinertial force on structure and function of the vestibular system. Investigations of basic vestibular physiology and of changes in reflexes occurring as a consequence of exposure to microgravity have important implications for diagnosis and treatment of vestibular disorders in human beings. This report reviews physiological principles underlying control of vestibular processes on earth and in space. Information is presented from a functional perspective with emphasis on signals arising from labyrinthine receptors. Changes induced by microgravity in linear acceleration detected by the vestibulo-ocular reflexes. Alterations of the functional requirements for postural control in space are described. Areas of direct correlation between studies of vestibular reflexes in microgravity and vestibular disorders in human beings are discussed.

  10. Effect of Target Location on Dynamic Visual Acuity During Passive Horizontal Rotation

    Science.gov (United States)

    Appelbaum, Meghan; DeDios, Yiri; Kulecz, Walter; Peters, Brian; Wood, Scott

    2010-01-01

    The vestibulo-ocular reflex (VOR) generates eye rotation to compensate for potential retinal slip in the specific plane of head movement. Dynamic visual acuity (DVA) has been utilized as a functional measure of the VOR. The purpose of this study was to examine changes in accuracy and reaction time when performing a DVA task with targets offset from the plane of rotation, e.g. offset vertically during horizontal rotation. Visual acuity was measured in 12 healthy subjects as they moved a hand-held joystick to indicate the orientation of a computer-generated Landolt C "as quickly and accurately as possible." Acuity thresholds were established with optotypes presented centrally on a wall-mounted LCD screen at 1.3 m distance, first without motion (static condition) and then while oscillating at 0.8 Hz (DVA, peak velocity 60 deg/s). The effect of target location was then measured during horizontal rotation with the optotypes randomly presented in one of nine different locations on the screen (offset up to 10 deg). The optotype size (logMar 0, 0.2 or 0.4, corresponding to Snellen range 20/20 to 20/50) and presentation duration (150, 300 and 450 ms) were counter-balanced across five trials, each utilizing horizontal rotation at 0.8 Hz. Dynamic acuity was reduced relative to static acuity in 7 of 12 subjects by one step size. During the random target trials, both accuracy and reaction time improved proportional to optotype size. Accuracy and reaction time also improved between 150 ms and 300 ms presentation durations. The main finding was that both accuracy and reaction time varied as a function of target location, with greater performance decrements when acquiring vertical targets. We conclude that dynamic visual acuity varies with target location, with acuity optimized for targets in the plane of motion. Both reaction time and accuracy are functionally relevant DVA parameters of VOR function.

  11. Pelviureteral inhibitory reflex and ureteropelvic excitatory reflex: role of the two reflexes in regulation of urine flow from the renal pelvis to the ureter.

    Science.gov (United States)

    Shafik, A

    1997-01-01

    The mechanism by which the ureteropelvic junction (UPJ) regulates the passage of urine from the renal pelvis to the ureter, and prevents urinary backflow from the the ureter to the renal pelvis, is not completely understood. The current communication studies this mechanism in 18 dogs. With the dogs under anesthesia, nephrostomy was done through which two catheters (one pressure and one balloon-tipped) were introduced into the UPJ and the renal pelvis, respectively. Renal pelvis distension with a balloon filled with 1 ml of saline effected a rise of renal pelvic pressure from a mean basal pressure of 4.8 +/- 1.2 cm H2O to 6.9 +/- 2.3 cm H2O (P pelvic balloon (P > 0.05). Renal pelvic distension with 2, 3, and 4 ml caused a significant rise of renal pelvic pressure to 8.4 +/- 2.7 (P elevation of ureteric and UPJ pressure which was not significantly different from that observed with distension with 0.5 ml (P > 0.05). In contrast, the UPJ showed no significant pressure change upon distension of the locally anesthetized renal pelvis or ureter, respectively. Likewise, the locally anesthetized UPJ exhibited no significant pressure response to renal pelvic or ureteric distension. The study demonstrates that urine might have to accumulate in the renal pelvis up to a certain volume and pressure so as to effect UPJ opening, which occurs at its maximum irrespective of the distending volume. UPJ opening upon renal pelvic distension postulates a reflex relationship which we call "pelviureteral inhibitory reflex." This reflex is believed to regulate the passage of urine from the renal pelvis to the ureter. Ureteric distension closes the UPJ; we call this reflex action the "ureteropelvic excitatory reflex" as it seems to prevent reflux of urine through the UPJ and thus protects the kidney. The concept that the UPJ acts as a physiologic sphincter is put forward.

  12. Hering-Breuer inflation reflex in young and adult mammals.

    Science.gov (United States)

    Gaultier, C; Mortola, J P

    1981-09-01

    The apnea following lung inflation (Hering-Breuer expiratory promoting reflex) is a vagally mediated reflex which is initiated by the activation of pulmonary stretch receptors (PSR) and terminated by the interaction of several factors, which include adaptation of PSR, chemical stimuli, level of anaesthesia, and body temperature. Since PSR activity is determined by the changes in airway tension, the interpretation of the strength of vagal reflexes on the basis of changes in lung volume rather than transpulmonary pressure can be misleading when the mechanical properties of the respiratory system are not constant. In this study we compared the reflex apnea resulting from lung inflation of young and adult mammals, the respiratory system it can be considered weaker or stronger in the young depending upon the normalizing parameter used. However, when considered on the basis of the relative changes in transpulmonary pressure, which better reflects the activation of PSR, the reflex is weaker in young rats and rabbits than in their adult counterparts an similar in dogs. The analysis of the underlying mechanisms suggests a weaker vagal contribution in the young animal, but a satisfactory conclusion requires a better knowledge of the factors which, in the younger animals, result in the termination of the apnea.

  13. Habituation and conditioning of the human long latency stretch reflex.

    Science.gov (United States)

    Rothwell, J C; Day, B L; Berardelli, A; Marsden, C D

    1986-01-01

    The effects of stretch repetition rate, prior warning stimuli and self administered stretch were examined on the size of the short and long latency components of the stretch reflex electromyographic EMG response in flexor pollicis longus and the flexor muscles of the wrist and fingers. Stretches of constant velocity and extent were given every 10 s, 5 s, 2 s, or 1 s to either the wrist or thumb during a small background contraction of the flexor muscles. The size of the long latency component of the stretch reflex (measured as the area under the averaged rectified EMG responses) declined dramatically at faster repetition rates, especially in the wrist and finger flexors. The size of the short latency component was relatively unaffected. The size of the electrically elicited H-reflex in forearm muscles also failed to habituate under the same conditions. If each individual trial of a series was examined, the long latency component of the stretch reflex EMG could be seen to decrease in size over the first three to six stretches if stretches were given every 1 s, but not if stretches were given every 10 s. When stretches were given every 5 s to either wrist or thumb, an electrical stimulus applied to the digital nerves of the opposite hand 1 s before stretch reduced the size of the long latency component of the reflex EMG response. The short latency component was unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Reflexivity, critical qualitative research and emancipation: a Foucauldian perspective.

    Science.gov (United States)

    McCabe, Janet L; Holmes, Dave

    2009-07-01

    In this paper, we consider reflexivity, not only as a concept of qualitative validity, but also as a tool used during the research process to achieve the goals of emancipation that are intrinsic to qualitative research conducted within a critical paradigm. Research conducted from a critical perspective poses two challenges to researchers: validity of the research must be ensured and the emancipatory aims of the research need to be realized and communicated. The traditional view of reflexivity as a means of ensuring validity in qualitative research limits its potential to inform the research process. The Medline and CINAHL data bases were searched (1998-2008 inclusive) using keywords such as reflexivity, validity, subjectivity, bias, emancipation, empowerment and disability. In addition, the work of Michel Foucault was examined. Using the work of the late French philosopher Michel Foucault, we explore how Foucault's 'technologies of the self' can be employed during critical qualitative research to achieve emancipatory changes. Using research conducted with marginalized populations as an example (specifically, individuals with disabilities), we demonstrate the potential for using reflexivity, in a Foucauldian sense, during the research process. Shifting the traditional view of reflexivity allows researchers to focus on the subtle changes that comprise emancipation (in a Foucauldian sense). As a result, researchers are better able to see, understand and analyse this process in both the participants and themselves.

  15. Nociception-specific blink reflex: pharmacology in healthy volunteers.

    Science.gov (United States)

    Marin, J C A; Gantenbein, A R; Paemeleire, K; Kaube, H; Goadsby, P J

    2015-01-01

    The physiology and pharmacology of activation or perception of activation of pain-coding trigeminovascular afferents in humans is fundamental to understanding the biology of headache and developing new treatments. The blink reflex was elicited using a concentric electrode and recorded in four separate sessions, at baseline and two minutes after administration of ramped doses of diazepam (final dose 0.07 mg/kg), fentanyl (final dose 1.11 μg/kg), ketamine (final dose 0.084 mg/kg) and 0.9 % saline solution. The AUC (area under the curve, μV*ms) and the latency (ms) of the ipsi- and contralateral R2 component of the blink reflex were calculated by PC-based offline analysis. Immediately after each block of blink reflex recordings certain psychometric parameters were assessed. There was an effect due to DRUG on the ipsilateral (F 3,60 = 7.3, P blink reflex (nBR) without any μ-opiate or glutamate NMDA receptor component. The nociception specific blink reflex offers a reproducible, quantifiable method of assessment of trigeminal nociceptive system in humans that can be used to dissect pharmacology relevant to primary headache disorders.

  16. Blink reflex role in algorithmic genetic testing of inherited polyneuropathies.

    Science.gov (United States)

    Wang, Wei; Litchy, William J; Mandrekar, Jay; Dyck, Peter J; Klein, Christopher J

    2017-03-01

    In severely affected inherited polyneuropathy patients, primary demyelination can be difficult to determine by routine extremity limb nerve conduction studies (NCS). Blink reflexes may help classify severe polyneuropathies as either axonal or demyelinating. However, blink reflex studies have not been studied systematically in any genetically confirmed cohort. Patients with a genetic diagnosis who had undergone blink reflex testing and extremity NCS were identified retrospectively. Blink reflex R1 latency, extremity NCS, and severity were compared. We identified 26 demyelinating and 23 axonal, genetically confirmed cases, including 20 with PMP22 duplications. In 12 (25%), the ulnar CMAP amplitude was ≤0.5 mV making electrophysiological classification difficult. However, the R1-latency cutoff of >13 ms (demyelinating) robustly classified all patients regardless of severity. We show that blink reflex studies are reliable for identification of inherited demyelinating polyneuropathy regardless of severity and can facilitate algorithmic decisions in genetic testing. Muscle Nerve 55: 316-322, 2017. © 2016 Wiley Periodicals, Inc.

  17. Trigeminocardiac Reflex: A Reappraisal with Relevance to Maxillofacial Surgery.

    Science.gov (United States)

    Bhargava, Darpan; Thomas, Shaji; Chakravorty, Nupur; Dutt, Ashutosh

    2014-12-01

    The purpose of this paper was to undertake a review of literature on trigeminocardiac reflex in oral and maxillofacial online data-base and discuss the pathophysiology, risk factor assessment, presentation of the reflex, prevention, management with emphasis on the role of the attending anaesthetist and the maxillofacial surgeon. The available literature relevant to oral and maxillofacial surgery in online data-base of the United States National Library of Medicine: Pubmed (http://www.ncbi.nlm.nih.gov/pubmed/) was searched. The inclusion criterion was to review published clinical papers, abstracts and evidence based reviews on trigeminocardiac reflex relevant to oral and maxillofacial surgery. Sixty-five articles were found with the search term "trigeminocardiac reflex" in the literature searched. Eighteen articles met the inclusion criteria for this study. The relevant data was extracted, tabulated and reviewed to draw evidence based conclusions for the management of trigeminocardiac reflex. Conclusions were drawn and discussed based on the reviewed maxillofacial literature with emphasis on the anaesthetist's and the surgeon's role in the management of this detrimental event in maxillofacial surgical practice.

  18. Trigemino-cervical-spinal reflexes after traumatic spinal cord injury.

    Science.gov (United States)

    Nardone, Raffaele; Höller, Yvonne; Orioli, Andrea; Brigo, Francesco; Christova, Monica; Tezzon, Frediano; Golaszewski, Stefan; Trinka, Eugen

    2015-05-01

    After spinal cord injury (SCI) reorganization of spinal cord circuits occur both above and below the spinal lesion. These functional changes can be determined by assessing electrophysiological recording. We aimed at investigating the trigemino-cervical reflex (TCR) and trigemino-spinal reflex (TSR) responses after traumatic SCI. TCR and TSR were registered after stimulation of the infraorbital nerve from the sternocleidomastoid, splenius, deltoid, biceps and first dorsal interosseous muscles in 10 healthy subjects and 10 subjects with incomplete cervical SCI. In the control subjects reflex responses were registered from the sternocleidomastoid, and splenium muscles, while no responses were obtained from upper limb muscles. In contrast, smaller but clear short latency EMG potentials were recorded from deltoid and biceps muscles in about half of the SCI patients. Moreover, the amplitudes of the EMG responses in the neck muscles were significantly higher in patients than in control subjects. The reflex responses are likely to propagate up the brainstem and down the spinal cord along the reticulospinal tracts and the propriospinal system. Despite the loss of corticospinal axons, synaptic plasticity in pre-existing pathways and/or formation of new circuits through sprouting processes above the injury site may contribute to the findings of this preliminary study and may be involved in the functional recovery. Trigemino-cervical-spinal reflexes can be used to demonstrate and quantify plastic changes at brainstem and cervical level following SCI. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  19. Reflexivity: a methodological tool in the knowledge translation process?

    Science.gov (United States)

    Alley, Sarah; Jackson, Suzanne F; Shakya, Yogendra B

    2015-05-01

    Knowledge translation is a dynamic and iterative process that includes the synthesis, dissemination, exchange, and application of knowledge. It is considered the bridge that closes the gap between research and practice. Yet it appears that in all areas of practice, a significant gap remains in translating research knowledge into practical application. Recently, researchers and practitioners in the field of health care have begun to recognize reflection and reflexive exercises as a fundamental component to the knowledge translation process. As a practical tool, reflexivity can go beyond simply looking at what practitioners are doing; when approached in a systematic manner, it has the potential to enable practitioners from a wide variety of backgrounds to identify, understand, and act in relation to the personal, professional, and political challenges they face in practice. This article focuses on how reflexive practice as a methodological tool can provide researchers and practitioners with new insights and increased self-awareness, as they are able to critically examine the nature of their work and acknowledge biases, which may affect the knowledge translation process. Through the use of structured journal entries, the nature of the relationship between reflexivity and knowledge translation was examined, specifically exploring if reflexivity can improve the knowledge translation process, leading to increased utilization and application of research findings into everyday practice. © 2015 Society for Public Health Education.

  20. Faroese long-distance reflexives face off against Icelandic long-distance reflexives

    Directory of Open Access Journals (Sweden)

    Tania E. Strahan

    2009-01-01

    Full Text Available Long-distance reflexives (LDRs in Faroese are often compared to those in Icelandic, and are even considered to have the same distribution (Thráinsson et al., 2004. In this paper I evaluate the extent to which this is true. The results from recent fieldwork show that there are clear differences between the LDR in the two closely related languages, in particular that Faroese speakers often reject LDR sentences that contain a non-third person, and that Faroese LDR is often completely acceptable out of a non-complement clause. In addition, initial findings suggest that there may be dialectal variation with respect to at least these two aspects of LDR in Faroese.

  1. Behavior of the long-latency stretch reflex prior to voluntary movement.

    Science.gov (United States)

    Hallett, M; Bielawski, M; Marsden, C D

    1981-08-24

    Attempts to elicit stretch reflexes from the 'relaxed' human long thumb flexor were made at various times prior to the onset of a voluntary contraction of that muscle. When the muscle was fully relaxed, there were no short or long-latency responses at the rates of stretch employed (about 600 degrees/sec). Without complete relaxation there was a small long-latency response, which occasionally increased in amplitude as the time for voluntary activation approached. This augmentation seemed to be a result of a subtle parallel augmentation of background EMG, anticipating the major voluntary contraction, thereby increasing the gain of the long-latency stretch response.

  2. Reflex anuria: a rare cause of acute kidney injury

    Directory of Open Access Journals (Sweden)

    Samuel Adediran

    2014-04-01

    Full Text Available Background: Acute Kidney Injury results from pre renal, post renal or intrinsic renal causes. Reflex anuria is a very rare cause of renal impairment which happens due to irritation or trauma to one kidney or ureter, or severely painful stimuli to other nearby organs. Case Presentation: Here we present a case of acute kidney injury secondary to reflex anuria in a patient who underwent extensive gynecological surgery along with ureteral manipulation which recovered spontaneously. Conclusion: Reflex Anuria is a rare and often not considered as cause of acute kidney injury. This case illustrates that this should be kept as a differential in potential cause of acute kidney injury in patient undergoing urogenital or gynecological surgeries.

  3. Pavlov on the conditioned reflex method and its limitations.

    Science.gov (United States)

    Windholz, G

    1995-01-01

    Pavlov's aim was to use the salivary conditioning method to investigate the function of the brain of higher animals in their adaptation to the external environment. The salivary reflex, according to Pavlov, was of minor biological significance but a good indicator of the subtle changes in the brain under different experimental conditions. To account for conditioned reflex phenomena, Pavlov faced two alternatives: to offer an objective (physiological) or a subjective (psychological) explanation. In 1901, after a bitter conflict with his disciple A. T. Snarskiy, Pavlov chose the first alternative. During the next decades, Pavlov provided reasons for this decision: The physiological approach (a) avoids anthropomorphizing or speculations about the dogs' subjective experiences, and (b) permits the explanation of observed phenomena which the subjective method is not capable of doing. Pavlov realized that the conditioned reflex method has a limitation; it cannot be used in the study of human subjects because their thinking interferes with experimental results.

  4. The frequency of buccopalpebral reflex in Parkinson disease.

    Science.gov (United States)

    Eser, Hülya; Ünal, Yasemin; Kutlu, Gülnihal; Öcal, Ruhsen; İnan, Levent Ertuğrul

    2016-11-17

    This study aimed to define the frequency of a primitive reflex, the buccopalpebral reflex (BPR), and its association with the clinical situation in patients with Parkinson disease. Between May 2010 and May 2011, 222 patients, 115 with Parkinson disease and 107 patients without any sign of neurodegenerative disease, were included in the study. All included patients were examined for BPR and snout reflex and were also evaluated with the Mini Mental State Examination. All patients with Parkinson disease were classified with the Unified Parkinson's Disease Rating Scale (UPDRS) and the Hoehn and Yahr Score to determine their clinical severity. Sixteen patients with Parkinson disease (13.9%) had a BPR (+) and 4 patients in the control group (3.7%) (P Parkinson disease than in patients without a neurodegenerative disease.

  5. Direct and consensual murine pupillary reflex metrics: establishing normative values.

    Science.gov (United States)

    Hussain, Rehana Z; Hopkins, Steven C; Frohman, Elliot M; Eagar, Todd N; Cravens, Petra C; Greenberg, Benjamin M; Vernino, Steven; Stüve, Olaf

    2009-12-03

    Pupillometry is a non-invasive technique, based on well-established neurophysiologic principles, that can be utilized to objectively characterize pathophysiologic demyelinating and neurodegenerative changes involving the pupillary reflex pathway. In animal models of human disorders, pupillometry derived reflex metrics could potentially be used to longitudinally monitor disease activity and responses to pharmacotherapies. These investigations would have important implications for translational initiatives focused on the identification and application of novel neuroprotective and restorative treatments for human diseases such as multiple sclerosis. Here, we have established normal reference values for various pupillary reflex metrics across different mouse strains. Ultimately, we anticipate that this new data will help to catalyze unique lines of inquiry using pupillometry methods.

  6. Adrenergic control of tendon jerk reflexes in man.

    Science.gov (United States)

    Phillips, S J; Richens, A; Shand, D G

    1973-03-01

    1. Tendon jerk responses and H reflexes were recorded from conscious human volunteers before and after intravenous injection of methylamphetamine, thymoxamine and propranolol, and during intravenous infusion of noradrenaline.2. Methylamphetamine produced a significant increase in the amplitude of the tendon jerk, whereas noradrenaline had no effect in doses which caused a greater pressor response than methylamphetamine.3. Thymoxamine produced a dose-related reduction in the tendon jerk.4. Propranolol had no significant effect on the jerk.5. None of these drugs significantly affected the H reflex.6. It is suggested that central adrenoceptors, possibly alpha in type, exist in man, and that stimulation of these receptors facilitates tendon jerk reflexes by an action on the fusimotor system.

  7. Automated data reduction workflows for astronomy. The ESO Reflex environment

    Science.gov (United States)

    Freudling, W.; Romaniello, M.; Bramich, D. M.; Ballester, P.; Forchi, V.; García-Dabló, C. E.; Moehler, S.; Neeser, M. J.

    2013-11-01

    Context. Data from complex modern astronomical instruments often consist of a large number of different science and calibration files, and their reduction requires a variety of software tools. The execution chain of the tools represents a complex workflow that needs to be tuned and supervised, often by individual researchers that are not necessarily experts for any specific instrument. Aims: The efficiency of data reduction can be improved by using automatic workflows to organise data and execute a sequence of data reduction steps. To realize such efficiency gains, we designed a system that allows intuitive representation, execution and modification of the data reduction workflow, and has facilities for inspection and interaction with the data. Methods: The European Southern Observatory (ESO) has developed Reflex, an environment to automate data reduction workflows. Reflex is implemented as a package of customized components for the Kepler workflow engine. Kepler provides the graphical user interface to create an executable flowchart-like representation of the data reduction process. Key features of Reflex are a rule-based data organiser, infrastructure to re-use results, thorough book-keeping, data progeny tracking, interactive user interfaces, and a novel concept to exploit information created during data organisation for the workflow execution. Results: Automated workflows can greatly increase the efficiency of astronomical data reduction. In Reflex, workflows can be run non-interactively as a first step. Subsequent optimization can then be carried out while transparently re-using all unchanged intermediate products. We found that such workflows enable the reduction of complex data by non-expert users and minimizes mistakes due to book-keeping errors. Conclusions: Reflex includes novel concepts to increase the efficiency of astronomical data processing. While Reflex is a specific implementation of astronomical scientific workflows within the Kepler workflow

  8. Facilitation of a nociceptive flexion reflex in man by nonnoxious radiant heat produced by a laser.

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    Plaghki, L; Bragard, D; Le Bars, D; Willer, J C; Godfraind, J M

    1998-05-01

    Electromyographic recordings were made in healthy volunteers from the knee-flexor biceps femoris muscle of the nociceptive RIII reflex elicited by electrical stimulation of the cutaneous sural nerve. The stimulus intensity was adjusted to produce a moderate pricking-pain sensation. The test responses were conditioned by a nonnoxious thermal (CO2 laser stimulator and consisted of a 100-ms pulse of heat with a beam diameter of 20 mm. Its power was 22.7 +/- 4.2 W (7.2 mJ/mm2), and it produced a sensation of warmth. The maximum surface temperature reached at the end of the period of stimulation was calculated to be 7 degrees C above the actual reference temperature of the skin (32 degrees C). The interval between the laser (conditioning) and electrical (test) stimuli was varied from 50 to 3, 000 ms in steps of 50 ms. It was found that the nociceptive flexion reflex was facilitated by the thermal stimulus; this modulation occurred with particular conditioning-test intervals, which peaked at 500 and 1,100 ms with an additional late, long-lasting phase between 1,600 and 2,300 ms. It was calculated that the conduction velocities of the cutaneous afferent fibers responsible for facilitating the RIII reflex, fell into three ranges: one corresponding to A delta fibers (3.2 m/s) and two in the C fiber range (1.3 and 0.7 m/s). It is concluded that information emanating from warm receptors and nociceptors converges. In this respect, the present data show, for the first time, that in man, conditioning nonnociceptive warm thermoreceptive A delta and C fibers results in an interaction at the spinal level with a nociceptive reflex. This interaction may constitute a useful means whereby signals add together to trigger flexion reflexes in defensive reactions and other basic motor behaviors. It also may contribute to hyperalgesia in inflammatory processes. The methodology used in this study appears to be a useful noninvasive tool for exploring the thermoalgesic mechanisms in both

  9. Synaptic plasticity in medial vestibular nucleus neurons: comparison with computational requirements of VOR adaptation.

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    John R W Menzies

    Full Text Available BACKGROUND: Vestibulo-ocular reflex (VOR gain adaptation, a longstanding experimental model of cerebellar learning, utilizes sites of plasticity in both cerebellar cortex and brainstem. However, the mechanisms by which the activity of cortical Purkinje cells may guide synaptic plasticity in brainstem vestibular neurons are unclear. Theoretical analyses indicate that vestibular plasticity should depend upon the correlation between Purkinje cell and vestibular afferent inputs, so that, in gain-down learning for example, increased cortical activity should induce long-term depression (LTD at vestibular synapses. METHODOLOGY/PRINCIPAL FINDINGS: Here we expressed this correlational learning rule in its simplest form, as an anti-Hebbian, heterosynaptic spike-timing dependent plasticity interaction between excitatory (vestibular and inhibitory (floccular inputs converging on medial vestibular nucleus (MVN neurons (input-spike-timing dependent plasticity, iSTDP. To test this rule, we stimulated vestibular afferents to evoke EPSCs in rat MVN neurons in vitro. Control EPSC recordings were followed by an induction protocol where membrane hyperpolarizing pulses, mimicking IPSPs evoked by flocculus inputs, were paired with single vestibular nerve stimuli. A robust LTD developed at vestibular synapses when the afferent EPSPs coincided with membrane hyperpolarization, while EPSPs occurring before or after the simulated IPSPs induced no lasting change. Furthermore, the iSTDP rule also successfully predicted the effects of a complex protocol using EPSP trains designed to mimic classical conditioning. CONCLUSIONS: These results, in strong support of theoretical predictions, suggest that the cerebellum alters the strength of vestibular synapses on MVN neurons through hetero-synaptic, anti-Hebbian iSTDP. Since the iSTDP rule does not depend on post-synaptic firing, it suggests a possible mechanism for VOR adaptation without compromising gaze-holding and VOR

  10. Prevalence of vestibular disorder in older people who experience dizziness

    Directory of Open Access Journals (Sweden)

    Allan T Chau

    2015-12-01

    Full Text Available Dizziness and imbalance are clinically poorly defined terms, which affect ~30% of people over 65 years of age. In these people it is often difficult to define the primary cause of dizziness, as it can stem from cardiovascular, vestibular, psychological and neuromuscular causes. However, identification of the primary cause is vital in determining the most effective treatment strategy for a patient. Our aim was to accurately identify the prevalence of: Benign Paroxysmal Positional Vertigo (BPPV, peripheral, and central vestibular hypofunction in people aged over 50 years who had experienced dizziness within the past year. Seventy six participants aged 51 to 92 (mean ± SD = 69 ± 9.5 years were tested using the Head Thrust Dynamic Visual Acuity (htDVA test, Dizziness Handicap Inventory (DHI, as well as sinusoidal and unidirectional rotational chair testing, in order to obtain data for: htDVA score; DHI score; sinusoidal (whole-body, 0.1 - 2 Hz with peak-velocity at 30deg/s Vestibulo-Ocular Reflex (VOR gain and phase; transient (whole-body, acceleration at 150deg/s/s to a constant velocity rotation of 50deg/s VOR gain and time constant; OptoKinetic Nystagmus (OKN gain and time constant (whole-body, constant velocity rotation at 50deg/s. We found that BPPV, peripheral and central vestibular hypofunction were present in 38% and 1% of participants respectively, suggesting a likely vestibular cause of dizziness in these people. Of those with a likely vestibular cause, 63% had BPPV; a figure higher than previously reported in dizziness clinics of ~25%. Our results indicate that htDVA, sinusoidal (particularly 0.5 - 1 Hz and transient VOR testing were the most effective at detecting people with BPPV or vestibular hypofunction, whereas DHI and OKN were effective at only detecting non-BPPV vestibular hypofunction.

  11. Latency of vestibular responses of pursuit neurons in the caudal frontal eye fields to whole body rotation.

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    Akao, Teppei; Saito, Hiroshi; Fukushima, Junko; Kurkin, Sergei; Fukushima, Kikuro

    2007-03-01

    The smooth pursuit system and the vestibular system interact to keep the retinal target image on the fovea by matching the eye velocity in space to target velocity during head and/or whole body movement. The caudal part of the frontal eye fields (FEF) in the fundus of the arcuate sulcus contains pursuit-related neurons and the majority of them respond to vestibular stimulation induced by whole body movement. To understand the role of FEF pursuit neurons in the interaction of vestibular and pursuit signals, we examined the latency and time course of discharge modulation to horizontal whole body rotation during different vestibular task conditions in head-stabilized monkeys. Pursuit neurons with horizontal preferred directions were selected, and they were classified either as gaze-velocity neurons or eye/head-velocity neurons based on the previous criteria. Responses of these neurons to whole body step-rotation at 20 degrees/s were examined during cancellation of the vestibulo-ocular reflex (VOR), VOR x1, and during chair steps in complete darkness without a target (VORd). The majority of pursuit neurons tested (approximately 70%) responded during VORd with latencies smooth pursuit. The shortest latency to the onset of target motion during smooth pursuit was 80 ms and the modal value was 95 ms. The time course of discharge rate difference of the two groups of neurons between VOR cancellation and x1 was predicted by the discharge modulation associated with smooth pursuit. These results provide further support for the involvement of the caudal FEF in integration of vestibular inputs and pursuit signals.

  12. There is still a role for the blink reflex in the diagnosis and follow-up of multiple sclerosis.

    Science.gov (United States)

    Brooks, Joseph Bruno Bidin; Jardim, Marcia Rodrigues; Papais-Alvarenga, Regina Maria; Fragoso, Yara Dadalti

    2015-04-01

    The evolution of the diagnostic criteria for multiple sclerosis (MS) has essentially evolved to clinical manifestations and magnetic resonance imaging. Inexpensive, quick to apply, non-invasive, quantitative and reliable neurophysiological tests are rare in daily practice and absent in clinical trials. The blink reflex was assessed in 50 patients with remitting-relapsing MS (RRMS) and 100 matched controls. Patients with RRMS had abnormalities in the blink reflex waves in relation to controls. If only RRMS patients were considered, these abnormalities were more pronounced in patients with longer disease duration, higher disability and for those with clinical or image lesions in the brainstem. Neurophysiological tests, such as the blink reflex, can be used for helping the diagnosis and follow-up of patients with RRMS, since the reflex can identify dissemination in time and in space in a clear and quantitative manner. Potential good methods for diagnosis and follow-up of MS should be considered for clinical trials and daily practice. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  13. Reconstructed bladder innervation below the level of spinal cord injury: the knee-tendon to bladder artificial reflex arc.

    Science.gov (United States)

    Zheng, Xian-You; Hou, Chun-Lin; Zhong, Hong-Bin; Xu, Rui-Sheng; Chen, Ai-Min; Xu, Zhen; Wang, Jian-Huo

    2009-01-01

    To study the effectiveness of knee-tendon to bladder artificial reflex arc in dogs. In 6 beagles, the proximal end of the right L5 anterior motor root and the distal end of the right S2 anterior root were anastomosed to build a knee-tendon to bladder reflex, whereas the right L5 posterior sensory root was kept intact. Action potential (AP) curves and electromyograms (EMGs) of the detrusor muscle, the intravesical pressure, horseradish peroxidase (HRP)-labeled neurons, and the passing rates of myelinic nerve fibers were calculated to evaluate its feasibility. AP curves and EMG detected in all 6 dogs were similar to those of the control. Six and 18 months after surgery, the means for bladder contraction induced by percussion of the right knee-tendon were 38 +/- 27% and 62 +/- 5% that of the normal control, respectively. The mean duration times induced by percussion of the right knee-tendon at 6 and 18 months after surgery were 51 +/- 37% and 84 +/- 12% that of the normal control, respectively. HRP retrograde tracing and neurohistologic observation indicated the feasibility of the artificial reflex arc. Our data showed the effectiveness of bladder innervation below the level of spinal cord injury producing urination by knee-tendon to bladder reflex contractions, and therefore, might provide a new clinical approach for restoring bladder function in individuals with paraplegia.

  14. A broadband acoustic stimulus is more likely than a pure tone to elicit a startle reflex and prepared movements.

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    Carlsen, Anthony N

    2015-08-01

    A loud acoustic stimulus that elicits a startle reflex has long been used to study the neurophysiology of cortical and subcortical neural circuits. More recent investigations have shown that startle can act as an early trigger for prepared actions, suggesting a brainstem role in the preparation and initiation of actions. However, in order to attribute any startle-triggered voluntary responses to activation in subcortical structures it is necessary to measure a startle-related activity in these structures. The current study investigated the most effective stimulus for eliciting a detectible startle reflex. While more intense stimuli are more likely to elicit a startle reflex, the current study examined whether broadband noise is more likely than a pure tone to produce a startle at various intensities above 100 dB. Participants performed a button release reaction time task in response to either a 1 kHz tone or a broadband noise pulse with intensities ranging from 82 to 124 dB. Reaction time and EMG from the wrist extensors and the sternocleidomastoid (SCM) were measured. Results showed that startle-related SCM EMG was elicited more frequently by broadband noise compared to pure tones. The higher proportion of startle reflexes observed in SCM was associated with a higher incidence of the voluntary task being triggered early. A higher incidence of startle following broadband noise is attributed to the activation of a larger proportion of the basilar membrane; thus, a lower intensity broadband noise stimulus may be used to elicit startle reflex at a similar rate as a higher intensity pure tone. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  15. Stretch Reflex as a Simple Measure to Evaluate the Efficacy of Potential Flight Countermeasures Using the Bed Rest Environment

    Science.gov (United States)

    Cerisano, J. M.; Reschke, M. F.; Kofman, I. S.; Fisher, E. A.; Harm, D. L.

    2010-01-01

    INTRODUCTION: Spaceflight is acknowledged to have significant effects on the major postural muscles. However, it has been difficult to separate the effects of ascending somatosensory changes caused by the unloading of these muscles during flight from changes in sensorimotor function caused by a descending vestibulo-cerebellar response to microgravity. It is hypothesized that bed rest is an adequate model to investigate postural muscle unloading given that spaceflight and bed rest may produce similar results in both nerve axon and muscle tissue. METHODS: To investigate this hypothesis, stretch reflexes were measured on 18 subjects who spent 60 to 90 days in continuous 6 head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 deg at a peak velocity of approximately 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender and compared with spaceflight data. RESULTS: Although no gender differences were found, bed rest induced changes in reflex latency and CV similar to the ones observed during spaceflight. Also, a relationship between CV and loss of muscle strength in the lower leg was observed for most bed rest subjects. CONCLUSION: Even though bed rest (limb unloading) alone may not mimic all of the synaptic and muscle tissue loss that is observed as a result of spaceflight, it can serve as a working analog of flight for the evaluation of potential countermeasures that may be beneficial in mitigating unwanted changes in the major postural muscles that are observed post flight.

  16. Alfentanil blocks reflex pupillary dilation in response to noxious stimulation but does not diminish the light reflex.

    Science.gov (United States)

    Larson, M D; Kurz, A; Sessler, D I; Dechert, M; Bjorksten, A R; Tayefeh, F

    1997-10-01

    Estimation of the mu-agonist opioid effect in anesthetized and paralyzed patients is often imprecise and can be obscured by concomitant administration of drugs that affect the sympathetic nervous system, such as beta-adrenergic blocking agents. As an alternative to hemodynamic measures of opioid effect, the authors tested the hypothesis that the pupillary light reflex or pupillary reflex dilation correlated with alfentanil concentrations during isoflurane anesthesia. Six volunteers were anesthetized on 4 days with 0.8% isoflurane. Alfentanil was administered intravenously to target total plasma concentrations of 0, 25, 50, and 100 ng/ml. A 5-s tetanic electrical stimulus was applied to the skin. Pupil size and the pupillary light reflex were recorded before and after alfentanil administration, and before and for 8 min after the stimulus. Alfentanil exponentially impaired reflex pupillary dilation, decreasing the maximum response amplitude from 5 mm at 0 ng/ml, to 2.3 mm at 25 ng/ml, to 1.0 mm at 50 ng/ml, and finally to 0.2 mm at 100 ng/ml. In contrast, only the highest concentration of alfentanil depressed the dilation of the pupil in the first 2 s after the stimulus. Alfentanil administration had no effect on the pupillary light reflex. Dilation of the pupil in response to a noxious stimulus is a measure of opioid effect in isoflurane-anesthetized volunteers. In contrast, the pupillary light reflex is unaffected by alfentanil during isoflurane anesthesia. These data suggest that stimulus-induced pupillary dilation may be used to evaluate the analgesic component of a combined volatile and opioid anesthetic.

  17. Effect of viewing distance on the generation of vertical eye movements during locomotion

    Science.gov (United States)

    Moore, S. T.; Hirasaki, E.; Cohen, B.; Raphan, T.

    1999-01-01

    Vertical head and eye coordination was studied as a function of viewing distance during locomotion. Vertical head translation and pitch movements were measured using a video motion analysis system (Optotrak 3020). Vertical eye movements were recorded using a video-based pupil tracker (Iscan). Subjects (five) walked on a linear treadmill at a speed of 1.67 m/s (6 km/h) while viewing a target screen placed at distances ranging from 0.25 to 2.0 m at 0. 25-m intervals. The predominant frequency of vertical head movement was 2 Hz. In accordance with previous studies, there was a small head pitch rotation, which was compensatory for vertical head translation. The magnitude of the vertical head movements and the phase relationship between head translation and pitch were little affected by viewing distance, and tended to orient the naso-occipital axis of the head at a point approximately 1 m in front of the subject (the head fixation distance or HFD). In contrast, eye velocity was significantly affected by viewing distance. When viewing a far (2-m) target, vertical eye velocity was 180 degrees out of phase with head pitch velocity, with a gain of 0. 8. This indicated that the angular vestibulo-ocular reflex (aVOR) was generating the eye movement response. The major finding was that, at a close viewing distance (0.25 m), eye velocity was in phase with head pitch and compensatory for vertical head translation, suggesting that activation of the linear vestibulo-ocular reflex (lVOR) was contributing to the eye movement response. There was also a threefold increase in the magnitude of eye velocity when viewing near targets, which was consistent with the goal of maintaining gaze on target. The required vertical lVOR sensitivity to cancel an unmodified aVOR response and generate the observed eye velocity magnitude for near targets was almost 3 times that previously measured. Supplementary experiments were performed utilizing body-fixed active head pitch rotations at 1 and 2 Hz

  18. Recreational soccer can improve the reflex response to sudden trunk loading among untrained women.

    Science.gov (United States)

    Pedersen, Mogens T; Randers, Morten B; Skotte, Jørgen H; Krustrup, Peter

    2009-12-01

    A slower reflex response to sudden trunk loading (SL) has been shown to increase future risk of low back injuries in healthy subjects, and specific readiness training can improve the response to SL among healthy subjects. The purpose of the study was to investigate the effect of recreational soccer training on the reaction to SL among untrained healthy women. Thirty-six healthy, untrained, Danish women (age 19-45 years) were randomly assigned to a soccer group (SO, n = 19) and a running group (RU, n = 17). In addition, an untrained control group (CON, n = 10) was recruited. Training was performed for 1 hour twice a week (mean heart rate of 165 b.min-1 in SO and 164 b.min-1 in RU) for 16 weeks. Test of reactions to sudden unexpected trunk loading was performed before and after the training period. Furthermore, time-motion analysis of the soccer training was performed for 9 subjects. Group assignment was blinded to the test personnel. Physical education students organized the training. During 1 hour of soccer training, the total number of sudden moves including sudden loading of the upper body (e.g. turns, stops, throw-ins, headers, and shoulder tackles) was 192 (63). In SO, time elapsed until stopping of the forward movement of the trunk (stopping time) decreased (p < 0.05) by 15% and distance moved after unexpected SL decreased (p < 0.05) by 24% compared with no changes in RU and CON. In conclusion, football training includes a high number of sudden loadings of the upper body and can improve the reflex response to SL. The faster reflex response indicates that soccer training can reduce the risk of low back injuries.

  19. Frequency response of human vestibular reflexes characterized by stochastic stimuli.

    Science.gov (United States)

    Dakin, Christopher J; Son, Gregory M Lee; Inglis, J Timothy; Blouin, Jean-Sébastien

    2007-09-15

    Stochastic vestibular stimulation (SVS) can be used to study the postural responses to unpredictable vestibular perturbations. The present study seeks to determine if stochastic vestibular stimulation elicits lower limb muscular responses and to estimate the frequency characteristics of these vestibulo-motor responses in humans. Fourteen healthy subjects were exposed to unpredictable galvanic currents applied on their mastoid processes while quietly standing (+/-3 mA, 0-50 Hz). The current amplitude and stimulation configuration as well as the subject's head position relative to their feet were manipulated in order to determine that: (1) the muscle responses evoked by stochastic currents are dependent on the amplitude of the current, (2) the muscle responses evoked by stochastic currents are specific to the percutaneous stimulation of vestibular afferents and (3) the lower limb muscle responses exhibit polarity changes with different head positions as previously described for square-wave galvanic vestibular stimulation (GVS) pulses. Our results revealed significant coherence (between 0 and 20 Hz) and cumulant density functions (peak responses at 65 and 103 ms) between SVS and the lower limbs' postural muscle activity. The polarity of the cumulant density functions corresponded to that of the reflexes elicited by square-wave GVS pulses. The SVS-muscle activity coherence and time cumulant functions were modulated by current amplitude, electrode position and head orientation with respect to the subject's feet. These findings strongly support the vestibular origin of the lower limb muscles evoked by SVS. In addition, specific frequency bandwidths in the stochastic vestibular signal contributed to the early (12-20 Hz) and late components (2-10 Hz) of the SVS-evoked muscular responses. These frequency-dependent SVS-evoked muscle responses support the view that the biphasic muscle response is conveyed by two distinct physiological processes.

  20. Vestibular perception following acute unilateral vestibular lesions.

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    Sian Cousins

    Full Text Available Little is known about the vestibulo-perceptual (VP system, particularly after a unilateral vestibular lesion. We investigated vestibulo-ocular (VO and VP function in 25 patients with vestibular neuritis (VN acutely (2 days after onset and after compensation (recovery phase, 10 weeks. Since the effect of VN on reflex and perceptual function may differ at threshold and supra-threshold acceleration levels, we used two stimulus intensities, acceleration steps of 0.5°/s(2 and velocity steps of 90°/s (acceleration 180°/s(2. We hypothesised that the vestibular lesion or the compensatory processes could dissociate VO and VP function, particularly if the acute vertiginous sensation interferes with the perceptual tasks. Both in acute and recovery phases, VO and VP thresholds increased, particularly during ipsilesional rotations. In signal detection theory this indicates that signals from the healthy and affected side are still fused, but result in asymmetric thresholds due to a lesion-induced bias. The normal pattern whereby VP thresholds are higher than VO thresholds was preserved, indicating that any 'perceptual noise' added by the vertigo does not disrupt the cognitive decision-making processes inherent to the perceptual task. Overall, the parallel findings in VO and VP thresholds imply little or no additional cortical processing and suggest that vestibular thresholds essentially reflect the sensitivity of the fused peripheral receptors. In contrast, a significant VO-VP dissociation for supra-threshold stimuli was found. Acutely, time constants and duration of the VO and VP responses were reduced - asymmetrically for VO, as expected, but surprisingly symmetrical for perception. At recovery, VP responses normalised but VO responses remained shortened and asymmetric. Thus, unlike threshold data, supra-threshold responses show considerable VO-VP dissociation indicative of additional, higher-order processing of vestibular signals. We provide evidence of

  1. Vestibular Migraine in Children and Adolescents: Clinical Findings and Laboratory Tests

    Science.gov (United States)

    Langhagen, Thyra; Lehrer, Nicole; Borggraefe, Ingo; Heinen, Florian; Jahn, Klaus

    2015-01-01

    Introduction: Vestibular migraine (VM) is the most common cause of episodic vertigo in children. We summarize the clinical findings and laboratory test results in a cohort of children and adolescents with VM. We discuss the limitations of current classification criteria for dizzy children. Methods: A retrospective chart analysis was performed on 118 children with migraine related vertigo at a tertiary care center. Patients were grouped in the following categories: (1) definite vestibular migraine (dVM); (2) probable vestibular migraine (pVM); (3) suspected vestibular migraine (sVM); (4) benign paroxysmal vertigo (BPV); and (5) migraine with/without aura (oM) plus vertigo/dizziness according to the International Classification of Headache Disorders, 3rd edition (beta version). Results: The mean age of all patients was 12 ± 3 years (range 3–18 years, 70 females). 36 patients (30%) fulfilled criteria for dVM, 33 (28%) for pVM, 34 (29%) for sVM, 7 (6%) for BPV, and 8 (7%) for oM. Somatoform vertigo (SV) co-occurred in 27% of patients. Episodic syndromes were reported in 8%; the family history of migraine was positive in 65%. Mild central ocular motor signs were found in 24% (most frequently horizontal saccadic pursuit). Laboratory tests showed that about 20% had pathological function of the horizontal vestibulo-ocular reflex, and almost 50% had abnormal postural sway patterns. Conclusion: Patients with definite, probable, and suspected VM do not differ in the frequency of ocular motor, vestibular, or postural abnormalities. VM is the best explanation for their symptoms. It is essential to establish diagnostic criteria in clinical studies. In clinical practice, however, the most reasonable diagnosis should be made in order to begin treatment. Such a procedure also minimizes the fear of the parents and children, reduces the need to interrupt leisure time and school activities, and prevents the development of SV. PMID:25674076

  2. Vestibular migraine in children and adolescents: clinical findings and laboratory tests

    Directory of Open Access Journals (Sweden)

    Thyra eLanghagen

    2015-01-01

    Full Text Available Introduction: Vestibular migraine (VM is the most common cause of episodic vertigo in children. We summarize the clinical findings and of laboratory test results in a cohort of children and adolescents with VM. We discuss the limitations of current classification criteria for dizzy children. Methods: A retrospective chart analysis was performed on 118 children with suspected VM at a tertiary care center. Patients with complaints related to migraine and who presented with vertigo/dizziness were grouped in the following categories: (1 definite vestibular migraine (dVM; (2 probable vestibular migraine (pVM; (3 suspected vestibular migraine (sVM; (4 benign paroxysmal vertigo (BPV; and (5 migraine with/without aura (oM according to the International Classification of Headache Disorders, 3rd edition (beta version. Results: The mean age of all patients was 12±3 years (range 3-18 years, 70 females. 36 patients (30% fulfilled criteria for dVM, 33 (28% for pVM, 34 (29% for sVM, 7 (6% for BPV, and 8 (7% for oM. Somatoform vertigo co-occurred in 27% patients. Episodic syndromes were reported in 8%; the family history of migraine was positive in 65%. Mild central ocular motor signs were found in 24% (most frequently horizontal saccadic pursuit. Laboratory tests showed that about 20% had pathological function of the horizontal vestibulo-ocular reflex, and almost 50% had abnormal postural sway patterns. Conclusion: Patients with definite, probable, and suspected VM do not differ in the frequency of ocular motor, vestibular, or postural abnormalities. VM is the best explanation for their symptoms. It is essential to establish diagnostic criteria in clinical studies. In clinical practice, however, the most reasonable diagnosis should be made in order to begin treatment. Such a procedure also minimizes the fear of the parents and children, reduces the need to interrupt leisure time and school activities, and prevents the development of somatoform vertigo.

  3. Gaze displacement and inter-segmental coordination during large whole body voluntary rotations.

    Science.gov (United States)

    Anastasopoulos, Dimitri; Ziavra, Nausica; Hollands, Mark; Bronstein, Adolfo

    2009-03-01

    Displacements of the visual axis and multi-segmental (eye-to-foot) coordination in the yaw plane were studied in ten human subjects (Ss) during voluntary reorientations to illuminated targets of eccentricities up to 180 degrees . We also investigated how knowledge of target location modifies the movement pattern. Eccentric targets (outbound trials) elicited eye, head, trunk and foot movements at latencies ca. 0.5, 0.6, 0.7 and 1.1 s, respectively. Knowledge of target location (return trials) reduced latencies for foot and trunk (but not eye and head) thus eye, head and trunk moved more en bloc. In most trials, the initial gaze shift fell short of the target and more than 50% of the visual angle was covered by the sum of vestibular nystagmic fast phases and head-in-space displacement, until target fixation. This indicates that during large gaze shifts the 'anticompensatory' role of the vestibulo-ocular reflex in target acquisition is prominent. During some predictable trials Ss acquired targets with a single large gaze shift, shortening target acquisition time by more than 200 ms. In these, gaze velocity (trunk-in-space + head-on-trunk + eye-in-orbit) remained often fairly constant for durations of up to 500 ms, suggesting that gaze velocity is a controlled parameter. Such pattern occurred during trunk mobilization, thus eye velocity co-varied with head-in-space rather than head-on-trunk velocity. Foot rotations were stereotyped and of constant frequency, suggesting they are generated by locomotor pattern generators. However, knowledge of target location reduced foot latencies indicating that local and supraspinal mechanisms interact for foot control. We propose that a single controller is responsible for the coupling of the multiple body segments and gaze velocity control during gaze shifts.

  4. Cerebellar motor learning: when is cortical plasticity not enough?

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    John Porrill

    2007-10-01

    Full Text Available Classical Marr-Albus theories of cerebellar learning employ only cortical sites of plasticity. However, tests of these theories using adaptive calibration of the vestibulo-ocular reflex (VOR have indicated plasticity in both cerebellar cortex and the brainstem. To resolve this long-standing conflict, we attempted to identify the computational role of the brainstem site, by using an adaptive filter version of the cerebellar microcircuit to model VOR calibration for changes in the oculomotor plant. With only cortical plasticity, introducing a realistic delay in the retinal-slip error signal of 100 ms prevented learning at frequencies higher than 2.5 Hz, although the VOR itself is accurate up to at least 25 Hz. However, the introduction of an additional brainstem site of plasticity, driven by the correlation between cerebellar and vestibular inputs, overcame the 2.5 Hz limitation and allowed learning of accurate high-frequency gains. This "cortex-first" learning mechanism is consistent with a wide variety of evidence concerning the role of the flocculus in VOR calibration, and complements rather than replaces the previously proposed "brainstem-first" mechanism that operates when ocular tracking mechanisms are effective. These results (i describe a process whereby information originally learnt in one area of the brain (cerebellar cortex can be transferred and expressed in another (brainstem, and (ii indicate for the first time why a brainstem site of plasticity is actually required by Marr-Albus type models when high-frequency gains must be learned in the presence of error delay.

  5. A new tool for investigating the functional testing of the VOR

    Directory of Open Access Journals (Sweden)

    Paolo eColagiorgio

    2013-10-01

    Full Text Available Peripheral vestibular function may be tested quantitatively, by measuring the gain of the angular vestibulo-ocular reflex (aVOR, or functionally, by assessing how well the aVOR performs with respect to its goal of stabilizing gaze in space and thus allow to acquire visual information during the head movement. In recent years, several groups have developed clinical and quantitative approaches to functional testing of the vestibular system based on the ability to identify an optotype briefly displayed on screen during head rotations.Although the proposed techniques differ in terms of the parameters controlling the testing paradigm, no study has thus far dealt with understanding the role of such choices in determining the effectiveness and reliability of the testing approach. Moreover, recent work has shown that peripheral vestibular patients may produce corrective saccades during the head movement (covert saccades, yet the role of these eye movements towards reading ability during head rotations is not yet understood. Finally, no study has thus far dealt with measuring the true performance of their experimental setups, which is nonetheless likely to be crucial information for understanding the effectiveness of functional testing approaches. Thus we propose a new software and hardware research tool allowing the combined measurement of eye and head movements, together with the timing of the optotype on screen, during functional testing of the VOR based on the Head Impulse Test (HIT. The goal of such tool is therefore that of allowing functional testing of the VOR while collecting the experimental data necessary to understand, for instance, a the effectiveness of the covert saccades strategy towards image stabilization, b which experimental parameters are crucial for optimizing the diagnostic power of the functional testing approach, and c which conditions lead to a successful reading or an error trial.

  6. Effects of the reappearance of primitive reflexes on eating function and prognosis.

    Science.gov (United States)

    Hobo, Kimiko; Kawase, Junko; Tamura, Fumiyo; Groher, Michael; Kikutani, Takeshi; Sunakawa, Hajime

    2014-01-01

    Primitive reflexes can reappear with diseases of the brain, particularly those affecting the frontal lobes. Most studies on primitive reflexes have reported an association between such reflexes and brain damage, and the clinical symptoms of dementia. These reflexes can also be present during eating; however, their effects on eating function are difficult to evaluate. The purpose of the present study was to identify the frequency at which primitive reflexes reappear in elderly people, and to determine the effects that such reflexes have on eating function, nutritional status and prognosis. We followed 121 nursing home residents for 6 months. All patients required long-term care and were examined for the presence of a sucking reflex, snout reflex and phasic bite reflex for baseline measures. Demographic characteristics, physical and cognitive function, and nutritional status were obtained from chart reviews, interviews with nurses, and a brief physical examination at baseline and incidence of aspiration pneumonia during the study period. The sucking reflex was confirmed in 31 patients (25.6%), snout reflex in 15 patients (12.3%) and phasic bite reflex in 28 patients (23.1%). One or more of these reflexes was identified in 38 patients (31.4%). A relationship between the presence of a primitive reflex and nutritional status was shown. An association with the presence of these reflexes and the development of aspiration pneumonia during 6 months was also confirmed. The appearance of primitive reflexes appears to be associated with the risk of malnutrition and developing aspiration pneumonia. © 2013 Japan Geriatrics Society.

  7. Intact thumb reflex in areflexic Guillain Barré syndrome: A novel phenomenon

    OpenAIRE

    Karkal Ravishankar Naik; Aralikatte Onkarappa Saroja; Manik Mahajan

    2014-01-01

    Introduction: Areflexia is one of the cardinal clinical features for the diagnosis of Guillain Barré syndrome. However, some patients may have sluggish proximal muscle stretch reflexes. Presence of thumb reflex, a distal stretch muscle reflex has not been documented in Guillain Barré syndrome. Materials and Methods: We prospectively evaluated thumb reflex in Guillain Barré syndrome patients and age matched controls from April to September 2013. Results: There were 31 patients with Guillain Ba...

  8. Obligatory Reflexivity in a Minimalist Grammar of Afrikaans ...

    African Journals Online (AJOL)

    Abstract. This paper deals with the phenomenon of obligatory reflexivity in Afrikaans. Adopting the general framework of Minimalist Syntax, an attempt is made to develop a novel analysis of this phenomenon that can provide a conceptually adequate account for the facts, and that is amenable to extension beyond Afrikaans.

  9. Reflexive modules with finite Gorenstein dimension with respect to a ...

    Indian Academy of Sciences (India)

    Proc. Indian Acad. Sci. (Math. Sci.) Vol. 125, No. 1, February 2015, pp. 21–28. c Indian Academy of Sciences. Reflexive modules with finite Gorenstein dimension with respect to a semidualizing module. ELHAM TAVASOLI1,∗, MARYAM SALIMI1 and SIAMAK YASSEMI2,3. 1Department of Mathematics, East Tehran Branch, ...

  10. Non-Grammatical Reflexive Binding Phenomena: The Case of Japanese.

    Science.gov (United States)

    Sakakibara, Sonoko

    Two non-syntactic phenomena of Japanese reflexive binding by "zibun" ("self") are analyzed with respect to a pragmatic use condition on "zibun," a culture-specific condition, and the Maxim of Politeness (Fukada 1986). The first phenomenon is the tendency by native speakers of Japanese to avoid referring to an honored…

  11. Reflex sympathetic dystrophy after modified radical mastectomy: a case report.

    Science.gov (United States)

    Saddison, D K; Vanek, V W

    1993-07-01

    Despite the long history of descriptions of reflex sympathetic dystrophy (RSD), much confusion remains regarding its pathogenesis, diagnosis, and treatment. It most commonly occurs after trauma and is more frequent in women, white persons, and the elderly. The first case of RSD after mastectomy is reported and the proposed pathophysiology and management of RSD are reviewed.

  12. Positioning Resumes and Cover Letters as Reflective-Reflexive Process

    Science.gov (United States)

    Randazzo, Chalice

    2012-01-01

    Although the resume and cover letter genre is widely discussed in both popular and scholarly publications, discussion thus far has failed to acknowledge that the process of creating a resume and cover letter has the potential for encouraging students' reflective and reflexive capacities. This article suggests that business communication educators…

  13. Shared bimanual tasks elicit bimanual reflexes during movement.

    Science.gov (United States)

    Mutha, Pratik K; Sainburg, Robert L

    2009-12-01

    Previous research has suggested distinct predictive and reactive control mechanisms for bimanual movements compared with unimanual motion. Recent studies have extended these findings by demonstrating that movement corrections during bimanual movements might differ depending on whether or not the task is shared between the arms. We hypothesized that corrective responses during shared bimanual tasks recruit bilateral rapid feedback mechanisms such as reflexes. We tested this hypothesis by perturbing one arm as subjects performed uni- and bimanual movements. Movements were made in a virtual-reality environment in which hand position was displayed as a cursor on a screen. During bimanual motion, we provided cursor feedback either independently for each arm (independent-cursor) or such that one cursor was placed at the average location between the arms (shared-cursor). On random trials, we applied a 40 N force pulse to the right arm 100 ms after movement onset. Our results show that while reflex responses were rapidly elicited in the perturbed arm, electromyographic activity remained close to baseline levels in the unperturbed arm during the independent-cursor trials. In contrast, when the cursor was shared between the arms, reflex responses were reduced in the perturbed arm and were rapidly elicited in the unperturbed arm. Our results thus suggest that when both arms contribute to achieving the task goal, reflex responses are bilaterally elicited in response to unilateral perturbations. These results agree with and extend recent suggestions that bimanual feedback control might be modified depending on task context.

  14. Neural reflex pathways in intestinal inflammation: hypotheses to viable therapy

    NARCIS (Netherlands)

    Willemze, Rose A.; Luyer, Misha D.; Buurman, Wim A.; de Jonge, Wouter J.

    2015-01-01

    Studies in neuroscience and immunology have clarified much of the anatomical and cellular basis for bidirectional interactions between the nervous and immune systems. As with other organs, intestinal immune responses and the development of immunity seems to be modulated by neural reflexes.

  15. Muscle reflex in heart failure: the role of exercise training.

    Science.gov (United States)

    Wang, Han-Jun; Zucker, Irving H; Wang, Wei

    2012-01-01

    Exercise evokes sympathetic activation and increases blood pressure and heart rate (HR). Two neural mechanisms that cause the exercise-induced increase in sympathetic discharge are central command and the exercise pressor reflex (EPR). The former suggests that a volitional signal emanating from central motor areas leads to increased sympathetic activation during exercise. The latter is a reflex originating in skeletal muscle which contributes significantly to the regulation of the cardiovascular and respiratory systems during exercise. The afferent arm of this reflex is composed of metabolically sensitive (predominantly group IV, C-fibers) and mechanically sensitive (predominately group III, A-delta fibers) afferent fibers. Activation of these receptors and their associated afferent fibers reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the sympathetic activation during exercise is exaggerated, which potentially increases cardiovascular risk and contributes to exercise intolerance during physical activity in chronic heart failure (CHF) patients. A therapeutic strategy for preventing or slowing the progression of the exaggerated EPR may be of benefit in CHF patients. Long-term exercise training (ExT), as a non-pharmacological treatment for CHF increases exercise capacity, reduces sympatho-excitation and improves cardiovascular function in CHF animals and patients. In this review, we will discuss the effects of ExT and the mechanisms that contribute to the exaggerated EPR in the CHF state.

  16. The plantar reflex : a historical, clinical and electromyographic study

    NARCIS (Netherlands)

    J. van Gijn (Jan)

    1977-01-01

    textabstractThe plantar reflex is one of the most important physical signs in medicine. Few patients undergoing a full medical examination can avoid having their soles stroked, because an upgoing great toe is regarded as a reliable sign of dysfunction of corticospinal nerve fibres. So far, there

  17. How to test for the red reflex in a child

    Directory of Open Access Journals (Sweden)

    Adapted from the poster: ‘See RED’ produced by JR Ainsworth, UK National Retinoblastoma Service, Birmingham, UK and the Childhood Eye Cancer Trust. www.chect.org.uk.

    2014-07-01

    Full Text Available Examination of pupil reflections, also known as the red reflex text, can reveal problems in the cornea, lens and sometimes the vitreous, and is particularly useful in young children. These photographs show what can occur in the case of certain major eye conditions, the most serious of which is retinoblastoma.

  18. Decreased fibularis reflex response during inversion perturbations in FAI subjects.

    Science.gov (United States)

    Donahue, Matthew S; Docherty, Carrie L; Riley, Zachary A

    2014-02-01

    Investigate reflex responses in muscles throughout the lower limb and low back during sudden inversion perturbations in individuals with and without Functional Ankle Instability (FAI) while walking. Forty subjects participated in the study. Surface electromyogram recordings were obtained from the fibularis (FIB), gluteus medius (GM), erector spinae (ES), and sternocleidomastoid (SCM) of the injured/matched side as well as the uninjured/matched contralateral side (FIB_CLS, GM_CLS, or ES_CLS). Latency and amplitude data were collected while subjects were walking on a custom-built perturbation walkway. The onset of the short-latency stretch reflex of the FIB was significantly later in the injured side of the FAI individuals when compared to the control group (P=0.009). Both the short and long latency reflex amplitude was significantly smaller in the FIB muscle in the FAI group than in the control group (P.05). Interpretation of these results indicate that during a dynamic perturbation task individuals with FAI demonstrate longer fibularis muscle latencies on the injured side while no significant changes in the proximal muscle groups. Additionally, short and long latency reflex amplitude was significantly decreased in FAI individuals. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Review article: Autonomous neural inflammatory reflex and control of

    African Journals Online (AJOL)

    Inflammation is common pathology associated with infections and other diseases process that lead to non specific sickness behaviours. Identification of autonomous neural inflammatory reflex that is regulated through autonomic nervous system and their receptors give a way forward on how this can be use as therapeutic ...

  20. Reflexive Pronouns in Dagbani Samuel Alhassan Issah1 Abstract ...

    African Journals Online (AJOL)

    Subject, Tense and Truth: Towards a Modular Approach to. Binding. In Gueron, Obenauer, and Pollock 1985: 259-292. Pica, P. 1987. On the Nature of the Reflexivization Cycle. In Proceedings of NELS 17: 483-499. GLSA, University of Massachusetts, Amherst. Rappaport, G. C. 1986. On Binding and Reflexives in Russian.

  1. Trait dominance promotes reflexive staring at masked angry body postures

    NARCIS (Netherlands)

    Hortensius, R.; van Honk, J.|info:eu-repo/dai/nl/188602801; De Gelder, B.; Terburg, D.|info:eu-repo/dai/nl/32304087X

    2014-01-01

    It has been shown that dominant individuals sustain eye-contact when non-consciously confronted with angry faces, suggesting reflexive mechanisms underlying dominance behaviors. However, dominance and submission can be conveyed and provoked by means of not only facial but also bodily features. So

  2. Power from Switching across Netdoms through Reflexive and Indexical Language.

    Directory of Open Access Journals (Sweden)

    Fontdevila, Jorge

    2010-06-01

    Full Text Available In differentiated societies with far-reaching yet fragmented social networks, the ability to manage pervasive ambiguity is crucial to navigate domination orders. In this paper we contend that identities, to enhance their control through switchings across networks and domains (netdoms, manage growing ambiguity via language’s reflexive and indexical features. We elaborate on several features—metapragmatics, heteroglossia, and poetics—and assert that they are seldom innocent performances to build consensus in the reproduction of social orders. On the contrary, language is inherently implicated in relations of domination. We then argue that metapragmatic control of stories acquired in countless netdom switchings leads to strong footings that secure resources and opportunity; that rhetorics that include rich heteroglossic voicing via structural holes generate stories that can be reflexively transposed to other institutional arenas; and that poetic control of speech styles may transform identities into power-law constellations with robust footing that decouple into prisms to preserve quality. Our goal is to twofold: First, to show that the reflexivity and indexicality of language emerges from myriad switchings across netdoms; and second, to demonstrate that reflexive and indexical language is critical to identities’ struggles for control—of footing and domination—via their switchings across rapidly polymerizing netdoms.

  3. Language Constructing Language: The Implications of Reflexivity for Linguistic Theory.

    Science.gov (United States)

    Taylor, Talbot J.

    2000-01-01

    Asks what first-order language might be like if there were no way to talk, write, or sign about it--that is, what if there were no second-order metalanguage. By considering the consequences for writing, translation, pragmatics, semantics, and language acquisition and evolution, it is suggested that without second-order, reflexive properties,…

  4. PhD Students, Interculturality, Reflexivity, Community and Internationalisation

    Science.gov (United States)

    Holliday, Adrian

    2017-01-01

    Interviews with a small group of doctoral students at a British university indicate that the students feel that the programme provides an environment within which they develop interculturality through reflexive engagement with the PhD community and in some cases with the participants in their research. Significant here is that they are…

  5. Capeverdean reflexives: the importance of a silent Voice

    Directory of Open Access Journals (Sweden)

    Fernanda Pratas

    2014-01-01

    Full Text Available In Capeverdean, a Portuguese-based Creole language, many reflexive contexts do not show any overt reflexive expression. This is the case of transitive verbs like bisti ‘dress’ in simple clauses: Ana bisti ‘Ana has dressed herself’. This is a perplexing fact, given that there is an anaphor of the SELF-type available in the language: (si kabesa — literally ‘his/her head’ —, meaning ‘himself/ herself’, which participates in reflexive clauses with other verbs. The current paper explores this puzzle, en-ding with a proposal supported empirically and also by recent studies for other languages. This novel analysis goes as follows: all Capeverdean finite sentences, except unaccusatives, have a Voice head, responsible for assigning external theta-roles. This also includes mid-dles, passives and this type of reflexives. It is this Voice head that, in spite of being silent, attracts the internal argument to a preverbal position and provides the interpretation for an implicit external argument, which is syntactically active.

  6. The masseteric reflex evoked by tooth and denture tapping.

    Science.gov (United States)

    Brodin, P; Fløystrand, F; Orstavik, J

    1991-07-01

    The characteristics of the masseter reflex evoked by tapping a maxillary incisor were compared with the reflex pattern evoked by tapping a corresponding denture tooth after insertion of an immediate denture. Up to three inhibitory phases (I-1, I-2 and I-3), followed by excitation, were found on an averaged EMG. The tapping force threshold for the early inhibitory phase was lower than for the late phases. The pattern of the reflex was generally the same before and after insertion of the denture, but the threshold values increased. After insertion of the denture, the threshold for I-1 increased from 1 +/- 0.3N to 2.2 +/- 0.4N, the threshold for I-2 increased from 2.4 +/- 0.8N to 3.8 +/- 0.9N, and the threshold for I-3 increased from 5.1 +/- 0.6N to 8.3 +/- 0.9N. The latency period for I-1 also increased from 12.3 +/- 0.5 ms to 13.1 +/- 0.3 ms after insertion of the denture. After relining, the threshold for evoking I-1 decreased from 2.7 +/- 1.2N to 1.2 +/- 0.6N. It was assumed that the mechanoreceptors situated in the mucosa under the denture base could take over the functional role of the periodontal mechanoreceptors for evoking the masseter reflex during tapping, and that these afferents probably had connections to the same interneurones.

  7. Soleus H-reflex excitability during pedaling post-stroke

    DEFF Research Database (Denmark)

    Schindler-Ivens, Sheila; Brown, David A.; Lewis, Gwyn N.

    2008-01-01

    A major contributor to impaired locomotion post-stroke is abnormal phasing of paretic muscle activity, but the mechanisms remain unclear. Previous studies have shown that, in the paretic limb of people post-stroke, Group Ia reflexes are abnormally elevated and fail to decrease in amplitude during...

  8. Cortical and cerebellar activation induced by reflexive and voluntary saccades

    NARCIS (Netherlands)

    C.K. Schraa-Tam (Caroline); P.C.A. van Broekhoven (Flip); J.N. van der Geest (Jos); M.A. Frens (Maarten); M. Smits (Marion); A. van der Lugt (Aad)

    2009-01-01

    textabstractReflexive saccades are driven by visual stimulation whereas voluntary saccades require volitional control. Behavioral and lesional studies suggest that there are two separate mechanisms involved in the generation of these two types of saccades. This study investigated differences in

  9. REFLEX CLOSURE OF THE OESOPHAGEAL GROOVE AND ITS ...

    African Journals Online (AJOL)

    The oesophageal groove reflex and indeed the very function of the oesophageal groove has intrigued physiolo- gists for some considerable period and very rightly so. lt has been generally agreed that the anatomical nature of the oesophageal groove enabled it to function as a con- tinuation of the oesophagus leading from ...

  10. Affective Modulation of the Startle Eyeblink and Postauricular Reflexes in Autism Spectrum Disorder

    Science.gov (United States)

    Dichter, Gabriel S.; Benning, Stephen D.; Holtzclaw, Tia N.; Bodfish, James W.

    2010-01-01

    Eyeblink and postauricular reflexes to standardized affective images were examined in individuals without (n = 37) and with (n = 20) autism spectrum disorders (ASDs). Affective reflex modulation in control participants replicated previous findings. The ASD group, however, showed anomalous reflex modulation patterns, despite similar self-report…

  11. A task dependent change in the medium latency component of the soleus stretch reflex

    DEFF Research Database (Denmark)

    Grey, Michael James; Larsen, Birgit; Sinkjær, Thomas

    2002-01-01

    In comparison to the H-reflex, the task dependency of the human stretch reflex during locomotive and postural tasks has not received a great deal of attention in the literature. The few studies on reflex task dependency that have been performed to date have concentrated on either the group Ia...

  12. The effects of neural synchronization and peripheral compression on the acoustic-reflex threshold

    DEFF Research Database (Denmark)

    Müller-Wehlau, Matthias; Mauermann, Manfred; Dau, Torsten

    2005-01-01

    This study investigates the acoustic reflex threshold (ART) dependency on stimulus phase utilizing low-level reflex audiometry [Neumann et al., Audiol. Neuro-Otol. 1, 359–369 (1996)]. The goal is to obtain optimal broadband stimuli for elicitation of the acoustic reflex and to obtain objective...

  13. Isometric and Dynamic Control of Neck Muscles : Reflexive contributions and muscle synergies

    NARCIS (Netherlands)

    De Bruijn, E.

    2014-01-01

    It is well established that the central nervous system (CNS) stabilizes the head using reflexive feedback and cocontraction. The major reflexive pathways in the neck are through muscle spindles generating the cervicocollic reflex (CCR) and through the vestibular organ generating the vestibulocollic

  14. O conceito de reflexão de Hegel como crítica aos conceitos de essência e de reflexão tradicionais

    Directory of Open Access Journals (Sweden)

    Christian Iber

    2017-02-01

    Full Text Available O presente artigo ilumina o específico do conceito de reflexão de Hegel em cinco momentos. Em um primeiro momento, delineia-se um esboço do conceito de reflexão na lógica da essência de Hegel. Em um segundo momento, o conceito de reflexão de Hegel é apresentado como estrutura lógica objetiva em contraste com a reflexão subjetiva da consciência e do entendimento, com a qual, ao mesmo tempo, o conceito de essência ontológica independente da reflexão é submetido a uma crítica. Do novo conceito de reflexão de Hegel resulta, em terceiro lugar, uma adaptação radical do círculo vicioso na teoria tradicional da reflexão da autoconsciência. Num quarto momento, lança-se um olhar sobre o conceito de reflexão anterior de Hegel como pensar do entendimento que separa, do qual o conceito de reflexão posterior se distingue. Por fim, apresenta-se, em quinto lugar, a lógica da reflexão de Hegel como crítica à fundação ontológica da reflexão em Schelling. O conceito de reflexão de Hegel se mostra, com isto, como crítica da metafísica ontológica tradicional e como fundação de uma metafísica da relacionalidade absoluta que supera a relatividade do pensar moderno do entendimento.

  15. Evaluation of cranial tibial and extensor carpi radialis reflexes before and after anesthetic block in cats.

    Science.gov (United States)

    Tudury, Eduardo Alberto; de Figueiredo, Marcella Luiz; Fernandes, Thaiza Helena Tavares; Araújo, Bruno Martins; Bonelli, Marília de Albuquerque; Diogo, Camila Cardoso; Silva, Amanda Camilo; Santos, Cássia Regina Oliveira; Rocha, Nadyne Lorrayne Farias Cardoso

    2017-02-01

    Objectives This study aimed to test the extensor carpi radialis and cranial tibial reflexes in cats before and after anesthetic block of the brachial and lumbosacral plexus, respectively, to determine whether they depend on a myotatic reflex arc. Methods Fifty-five cats with a normal neurologic examination that were referred for elective gonadectomy were divided into group 1 (29 cats) for testing the extensor carpi radialis reflex, and group 2 (26 cats) for testing the cranial tibial reflex. In group 1, the extensor carpi radialis reflex was tested after anesthetic induction and 15 mins after brachial plexus block with lidocaine. In group 2, the cranial tibial, withdrawal and patellar reflexes were elicited in 52 hindlimbs and retested 15 mins after epidural anesthesia. Results In group 1, before the anesthetic block, 55.17% of the cats had a decreased and 44.83% had a normal extensor carpi radialis reflex. After the block, 68.96% showed a decreased and 27.59% a normal reflex. No cat had an increased or absent reflex before anesthetic block. In group 2, prior to the anesthetic block, 15.38% of the cats had a decreased cranial tibial reflex and 84.62% had a normal response, whereas after the block it was decreased in 26.92% and normal in 73.08% of the cats. None of the cats had an increased or absent reflex. Regarding the presence of both reflexes before and after anesthetic block, there was no significant difference at 1% ( P = 0.013). Conclusions and relevance The extensor carpi radialis and cranial tibial reflexes in cats are not strictly myotatic reflexes, as they are independent of the reflex arc, and may be idiomuscular responses. Therefore, they are not reliable for neurologic examination in this species.

  16. From ear to uncertainty: Vestibular contributions to cognitive function.

    Directory of Open Access Journals (Sweden)

    Paul eSmith

    2013-11-01

    Full Text Available In addition to the deficits in the vestibulo-ocular and vestibulo-spinal reflexes that occur following vestibular dysfunction, there is substantial evidence that vestibular loss also causes cognitive disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and cortex play in spatial orientation. In this review we summarise the evidence that vestibular loss causes cognitive disorders, especially spatial memory deficits, in animals and humans and critically evaluate the evidence that these deficits are not due to hearing loss, problems with motor control, oscillopsia or anxiety and depression. We review the evidence that vestibular lesions affect head direction and place cells as well as the emerging evidence that artificial activation of the vestibular system, using galvanic vestibular stimulation, can modulate cognitive function.

  17. From ear to uncertainty: vestibular contributions to cognitive function.

    Science.gov (United States)

    Smith, Paul F; Zheng, Yiwen

    2013-11-26

    In addition to the deficits in the vestibulo-ocular and vestibulo-spinal reflexes that occur following vestibular dysfunction, there is substantial evidence that vestibular loss also causes cognitive disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and neocortex play in spatial orientation. In this review we summarize the evidence that vestibular loss causes cognitive disorders, especially spatial memory deficits, in animals and humans and critically evaluate the evidence that these deficits are not due to hearing loss, problems with motor control, oscillopsia or anxiety and depression. We review the evidence that vestibular lesions affect head direction and place cells as well as the emerging evidence that artificial activation of the vestibular system, using galvanic vestibular stimulation (GVS), can modulate cognitive function.

  18. Effect of transcranial direct current stimulation on vestibular-ocular and vestibulo-perceptual thresholds.

    Science.gov (United States)

    Kyriakareli, Artemis; Cousins, Sian; Pettorossi, Vito E; Bronstein, Adolfo M

    2013-10-02

    Transcranial direct current stimulation (tDCS) was used in 17 normal individuals to modulate vestibulo-ocular reflex (VOR) and self-motion perception rotational thresholds. The electrodes were applied over the temporoparietal junction bilaterally. Both vestibular nystagmic and perceptual thresholds were increased during as well as after tDCS stimulation. Body rotation was labeled as ipsilateral or contralateral to the anode side, but no difference was observed depending on the direction of rotation or hemisphere polarity. Threshold increase during tDCS was greater for VOR than for motion perception. 'Sham' stimulation had no effect on thresholds. We conclude that tDCS produces an immediate and sustained depression of cortical regions controlling VOR and movement perception. Temporoparietal areas appear to be involved in vestibular threshold modulation but the differential effects observed between VOR and perception suggest a partial dissociation between cortical processing of reflexive and perceptual responses.

  19. Migraine patients consistently show abnormal vestibular bedside tests

    Directory of Open Access Journals (Sweden)

    Eliana Teixeira Maranhão

    2015-01-01

    Full Text Available Migraine and vertigo are common disorders, with lifetime prevalences of 16% and 7% respectively, and co-morbidity around 3.2%. Vestibular syndromes and dizziness occur more frequently in migraine patients. We investigated bedside clinical signs indicative of vestibular dysfunction in migraineurs.Objective To test the hypothesis that vestibulo-ocular reflex, vestibulo-spinal reflex and fall risk (FR responses as measured by 14 bedside tests are abnormal in migraineurs without vertigo, as compared with controls.Method Cross-sectional study including sixty individuals – thirty migraineurs, 25 women, 19-60 y-o; and 30 gender/age healthy paired controls.Results Migraineurs showed a tendency to perform worse in almost all tests, albeit only the Romberg tandem test was statistically different from controls. A combination of four abnormal tests better discriminated the two groups (93.3% specificity.Conclusion Migraine patients consistently showed abnormal vestibular bedside tests when compared with controls.

  20. The artificial somato-autonomic reflex arch does not improve bowel function in subjects with spinal cord injury

    DEFF Research Database (Denmark)

    Rasmussen, Mikkel Mylius; Krogh, Klaus; Clemmensen, Dorte

    2015-01-01

    : Denmark. Methods: Ten subjects with supraconal spinal cord injury (SCI) (nine males, median age 46 years) had an anastomosis created between the ventral part of the fifth lumbar or first sacral nerve root and the ventral part of the second sacral nerve root. Standardized assessment of segmental colorectal...... transit times with radiopaque markers, evaluation of scintigraphic assessed colorectal emptying upon defecation, scintigraphic assessment of colorectal transport during stimulation of the reflex arch, standard anorectal physiology tests and colorectal symptoms were performed at baseline and 18 months...... after surgery. Results: No significant change was observed in colorectal emptying upon defecation (median 31% of the rectosigmoid at baseline vs 75% at follow-up, P=0.50), no movement of colorectal contents was observed during stimulation of the reflex arch. Segmental colorectal transit times, anal...

  1. Suppression of reflex urethral responses by sacral dermatome stimulation in an acute spinalized feline model

    Science.gov (United States)

    Mariano, Timothy Y.; Bhadra, Narendra; Gustafson, Kenneth J.

    2010-01-01

    Aims Reflex contractions of the external urethral sphincter (EUS) are a major component of voiding dysfunction after neurological injury or disease. Aberrant urethral reflexes can prevent voiding and cause serious medical complications. Characterizing these urethral reflexes during genitourinary studies is necessary for evaluating novel pharmacological or neuroprosthetic approaches. The objectives of the present study were to generate urethral reflexes in the acute spinal feline, to quantify these reflexes, and to suppress them with electrical stimulation of the sacral dermatomes. Methods This study comprised eight male cats. Anaesthesia was maintained with alpha-chloralose or sodium pentobarbital. The spinal cord was transected between T10 and T12, and nerve cuff electrodes were placed on the extradural S2 sacral roots to provide bladder activation. Bladder and urethral pressures were recorded during and after bladder contractions. Electrical stimulation was applied non-invasively to the sacral dermatomes with commercial surface electrodes. Results Urethral reflexes were elicited consistently in six cats. The corresponding urethral pressure spikes were quantified. Putative metrics of urethral reflex activity such as the rate and average magnitude of reflex pressure spikes correlated significantly with standard urodynamic variables. Electrical stimulation of the sacral dermatomes suppressed urethral reflexes in three cats. Conclusions These findings in an acute spinal feline preparation demonstrate a non-invasive means of suppressing undesirable urethral reflexes. Translation of this work to clinical use could improve neuroprostheses for restoring bladder function and enhance treatment of aberrant urethral reflexes in humans. PMID:19283867

  2. Intact thumb reflex in areflexic Guillain Barré syndrome: A novel phenomenon

    Directory of Open Access Journals (Sweden)

    Karkal Ravishankar Naik

    2014-01-01

    Full Text Available Introduction: Areflexia is one of the cardinal clinical features for the diagnosis of Guillain Barré syndrome. However, some patients may have sluggish proximal muscle stretch reflexes. Presence of thumb reflex, a distal stretch muscle reflex has not been documented in Guillain Barré syndrome. Materials and Methods: We prospectively evaluated thumb reflex in Guillain Barré syndrome patients and age matched controls from April to September 2013. Results: There were 31 patients with Guillain Barrι syndrome in whom thumb reflex could be elicited in all (24 brisk, 7 sluggish, whereas all the other muscle stretch reflexes were absent in 29 patients at presentation and the remaining two had sluggish biceps and quadriceps reflexes (P = 0.001. Serial examination revealed gradual diminution of the thumb reflex (P < 0.001. Rapid progression of weakness was associated with early loss of the thumb reflex. Conclusion: Thumb reflex, a distal stretch reflex is preserved in the early phase of Guillain Barré syndrome.

  3. Priming Neural Circuits to Modulate Spinal Reflex Excitability

    Science.gov (United States)

    Estes, Stephen P.; Iddings, Jennifer A.; Field-Fote, Edelle C.

    2017-01-01

    While priming is most often thought of as a strategy for modulating neural excitability to facilitate voluntary motor control, priming stimulation can also be utilized to target spinal reflex excitability. In this application, priming can be used to modulate the involuntary motor output that often follows central nervous system injury. Individuals with spinal cord injury (SCI) often experience spasticity, for which antispasmodic medications are the most common treatment. Physical therapeutic/electroceutic interventions offer an alternative treatment for spasticity, without the deleterious side effects that can accompany pharmacological interventions. While studies of physical therapeutic/electroceutic interventions have been published, a systematic comparison of these approaches has not been performed. The purpose of this study was to compare four non-pharmacological interventions to a sham-control intervention to assess their efficacy for spasticity reduction. Participants were individuals (n = 10) with chronic SCI (≥1 year) who exhibited stretch-induced quadriceps spasticity. Spasticity was quantified using the pendulum test before and at two time points after (immediate, 45 min delayed) each of four different physical therapeutic/electroceutic interventions, plus a sham-control intervention. Interventions included stretching, cyclic passive movement (CPM), transcutaneous spinal cord stimulation (tcSCS), and transcranial direct current stimulation (tDCS). The sham-control intervention consisted of a brief ramp-up and ramp-down of knee and ankle stimulation while reclined with legs extended. The order of interventions was randomized, and each was tested on a separate day with at least 48 h between sessions. Compared to the sham-control intervention, stretching, CPM, and tcSCS were associated with a significantly greater reduction in spasticity immediately after treatment. While the immediate effect was largest for stretching, the reduction persisted

  4. Tonic Stretch Reflex Threshold as a Measure of Ankle Plantar-Flexor Spasticity After Stroke.

    Science.gov (United States)

    Blanchette, Andreanne K; Mullick, Aditi A; Moïn-Darbari, Karina; Levin, Mindy F

    2016-05-01

    Commonly used spasticity scales assess the resistance felt by the evaluator during passive stretching. These scales, however, have questionable validity and reliability. The tonic stretch reflex threshold (TSRT), or the angle at which motoneuronal recruitment begins in the resting state, is a promising alternative for spasticity measurement. Previous studies showed that spasticity and voluntary motor deficits after stroke may be characterized by a limitation in the ability of the central nervous system to regulate the range of the TSRT. The study objective was to assess interevaluator reliability for TSRT plantar-flexor spasticity measurement. This was an interevaluator reliability study. In 28 people after stroke, plantar-flexor spasticity was evaluated twice on the same day. Plantar-flexor muscles were stretched 20 times at different velocities assigned by a portable device. Plantar-flexor electromyographic signals and ankle angles were used to determine dynamic velocity-dependent thresholds. The TSRT was computed by extrapolating a regression line through dynamic velocity-dependent thresholds to the angular axis. Mean TSRTs in evaluations 1 and 2 were 66.0 degrees (SD=13.1°) and 65.8 degrees (SD=14.1°), respectively, with no significant difference between them. The intraclass correlation coefficient (2,1) was .851 (95% confidence interval=.703, .928). The notion of dynamic stretch reflex threshold does not exclude the possibility that spasticity is dependent on acceleration, as well as on velocity; future work will study both possibilities. Tonic stretch reflex threshold interevaluator reliability for evaluating stroke-related plantar-flexor spasticity was very good. The TSRT is a reliable measure of spasticity. More information may be gained by combining the TSRT measurement with a measure of velocity-dependent resistance. © 2016 American Physical Therapy Association.

  5. An Efficient Algorithm for the Reflexive Solution of the Quaternion Matrix Equation AXB+CXHD=F

    Directory of Open Access Journals (Sweden)

    Ning Li

    2013-01-01

    Full Text Available We propose an iterative algorithm for solving the reflexive solution of the quaternion matrix equation AXB+CXHD=F. When the matrix equation is consistent over reflexive matrix X, a reflexive solution can be obtained within finite iteration steps in the absence of roundoff errors. By the proposed iterative algorithm, the least Frobenius norm reflexive solution of the matrix equation can be derived when an appropriate initial iterative matrix is chosen. Furthermore, the optimal approximate reflexive solution to a given reflexive matrix X0 can be derived by finding the least Frobenius norm reflexive solution of a new corresponding quaternion matrix equation. Finally, two numerical examples are given to illustrate the efficiency of the proposed methods.

  6. Rate of EGFR mutation testing for patients with nonsquamous non-small-cell lung cancer with implementation of reflex testing by pathologists

    Science.gov (United States)

    Cheema, P.K.; Raphael, S.; El-Maraghi, R.; Li, J.; McClure, R.; Zibdawi, L.; Chan, A.; Victor, J.C.; Dolley, A.; Dziarmaga, A.

    2017-01-01

    Background Testing for mutation of the EGFR (epidermal growth factor receptor) gene is a standard of care for patients with advanced nonsquamous non-small-cell lung cancer (nsclc). To improve timely access to EGFR results, a few centres implemented reflex testing, defined as a request for EGFR testing by the pathologist at the time of a nonsquamous nsclc diagnosis. We evaluated the impact of reflex testing on EGFR testing rates. Methods A retrospective observational review of the Web-based AstraZeneca Canada EGFR Database from 1 April 2010 to 31 March 2014 found centres within Ontario that had requested EGFR testing through the database and that had implemented reflex testing (with at least 2 years’ worth of data, including the pre- and post-implementation period). Results The 7 included centres had requested EGFR tests for 2214 patients. The proportion of pathologists requesting EGFR tests increased after implementation of reflex testing (53% vs. 4%); conversely, the proportion of medical oncologists requesting tests decreased (46% vs. 95%, p testing, the mean number of patients having EGFR testing per centre per month increased significantly [12.6 vs. 4.9 (range: 4.5–14.9), p testing, EGFR testing rates showed a significant monthly increase over time (1.37 more tests per month; 95% confidence interval: 1.19 to 1.55 tests; p testing, because an immediate increase in EGFR test requests was observed with the introduction of reflex testing (p = 0.003), and the overall trend was sustained throughout the post–reflex testing period (p testing for patients with nonsquamous nsclc was successfully implemented at multiple centres and was associated with an increase in EGFR testing. PMID:28270720

  7. Prepulse inhibition and facilitation of the postauricular reflex, a vestigial remnant of pinna startle.

    Science.gov (United States)

    Hackley, Steven A; Ren, Xi; Underwood, Amy; Valle-Inclán, Fernando

    2017-04-01

    If the postauricular reflex (PAR) is to be used effectively in studies of emotion and attention, its sensitivity to basic modulatory effects such as prepulse inhibition and facilitation must be determined. Two experiments were carried out with healthy young adults to assess the effects of transient and sustained visual prestimuli on the pinna-flexion response to trains of startle probes. In the first experiment, participants passively viewed a small white square. It was displayed from 1,000 ms prior to onset of a train of noise bursts until the end of that train. Relative to no-prepulse control trials, PAR amplitude was inhibited, possibly due to the withdrawal of attentional resources from the auditory modality. In the second experiment, participants performed a visual oddball task in which irrelevant trains of startle probes followed most briefly displayed task stimuli (checkerboards). Prepulse inhibition was observed when a transient stimulus preceded the first probe at a lead time of 100 ms. Amplitude facilitation was observed at longer lead times. In addition to documenting the existence of prepulse inhibition and facilitation, the data suggest that the PAR is not elicited by visual stimuli, that temporal expectancy does not influence its amplitude or latency, and that this vestigial microreflex is resistant to habituation. Results are interpreted in light of a recent theory that the human PAR is a highly degraded pinna startle, in which the reflex arc no longer includes the startle center (nucleus reticularis pontis caudalis). © 2017 Society for Psychophysiological Research.

  8. Abnormal oculocardiac reflex in two patients with Marcus Gunn syndrome

    Directory of Open Access Journals (Sweden)

    Maitree Pandey

    2011-01-01

    Full Text Available Marcus Gunn phenomenon is seen in 4 to 6% of congenital ptosis patients. We report two cases of abnormal oculocardiac reflex during ptosis correction surgery. Marcus Gunn syndrome is an autosomal dominant condition with incomplete penetrance. It is believed to be a neural misdirection syndrome in which fibres of the motor division of the trigeminal nerve are congenitally misdirected into the superior pterygoid and the levator muscles. Anesthetic considerations include taking a detailed history about any previous anaesthetic exposure and any reaction to it as this syndrome has a high probability of being associated with malignant hyperthermia. It is also postulated that an atypical oculocardiac reflex might be initiated in these patients as seen in our patients, so precautions must be taken for its prevention and early detection.

  9. Review Essay: Grenzgänger Seeks Reflexive Methodology

    Directory of Open Access Journals (Sweden)

    Wolff-Michael Roth

    2002-09-01

    Full Text Available Reflexive Methodology reviews major strands of current thought in epistemology, philosophy, social science, and interpretive methods. The book falls short in that it neither does a thorough job reviewing the literature nor does it provide method-related advice useful to students. Grenzgängerin constitutes a collection of essays on a broad range of topics, but which are only loosely connected if at all. Drawing on DERRIDA and the notion of a historical science of the historical subject, I attempt to practice method, something I missed in both texts. I make explicit the historical nature of my own writing and the historical nature of my subject. I make explicit intertextuality and in the process practice reflexivity in the particular way I am writing. URN: urn:nbn:de:0114-fqs020328

  10. Teacher education and the challenges of the reflexive practice

    Directory of Open Access Journals (Sweden)

    Maria Regina Peres

    2013-06-01

    Full Text Available This article approaches the importance of teacher practice and their initial and continuing education in the light of the challenges offered by the critical reflexive proposal. The aims of this study were to investigate the underlying assumptions regarding teachers’ current education and practice, to research and analyze the major difficulties found in the development of teaching practice, to comprehend and analyze the complexity inherent to the teacher’s performance in the initial years of elementary school. A bibliographic research and a qualitative research with elementary school teachers were therefore developed. The results indicate that although teachers believe the learning process to be continuous, they do not invest in this type of education. Furthermore it was found that teachers’ critical reflexive attitudes are blended with eproductivist attitudes.

  11. Startle and blink reflex in high functioning autism.

    Science.gov (United States)

    Erturk, Ozdem; Korkmaz, Baris; Alev, Gulce; Demirbilek, Veysi; Kiziltan, Meral

    2016-06-01

    An important clinical feature of autism is the presence of atypical responses to sensory stimuli. In this study, we investigated if high functioning autistic patients had abnormalities in the blink reflex and the startle reaction to auditory or somatosensory stimuli. Fourteen patients aged between 7 and 16 years were included in the study. We found a longer latency of the blink reflex, an increased duration and amplitude of the auditory startle reaction and a lower presence rate of the somatosensorial startle reaction in autistic patients. To better define the sensorial characteristics of the disease could improve the therapeutic management of children with autism spectrum disorder. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. Altered pupillary light reflex in PACAP receptor 1-deficient mice

    DEFF Research Database (Denmark)

    Engelund, Anna; Fahrenkrug, Jan; Harrison, Adrian Paul

    2012-01-01

    The pupillary light reflex (PLR) is regulated by the classical photoreceptors, rods and cones, and by intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin. IpRGCs receive input from rods and cones and project to the olivary pretectal nucleus (OPN......), which is the primary visual center involved in PLR. Mice lacking either the classical photoreceptors or melanopsin exhibit some changes in PLR, whereas the reflex is completely lost in mice deficient of all three photoreceptors. The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP......) is co-stored with melanopsin in ipRGCs and mediates light signaling to the brain via the specific PACAP receptor 1 (PAC1R). Here, we examined the occurrence of PACAP and PAC1R in the mouse OPN, and studied if lack of PAC1R affected the PLR. PACAP-immunoreactive nerve fibers were shown in the mouse OPN...

  13. Becoming Bermuda grass: mapping and tracing rhizomes to practice reflexivity

    Science.gov (United States)

    Murakami, Christopher D.; Siegel, Marcelle A.

    2017-09-01

    This narrative project used rhizomatic analysis and reflexivity to describe a layered process of responding to a student's identity of non-participation within an undergraduate science classroom. Mapping rhizomes represents an ongoing and experimental process in consciousness. Rhizomatic mapping in educational studies is too often left out of the products of academic pursuits. In this paper, we try to capture this process, and let the process capture us. This manuscript starts with a focus on just one student, but maps our reflexive terrain that helped us think in new ways about persistent problems in science learning. As we decided how to address this student's identity of non-participation, we learned about the intertwined stories of the researchers and the researched and the challenges of designing inclusive learning environments.

  14. "A case of self-induced reflex epilepsy "

    Directory of Open Access Journals (Sweden)

    "Moatamedi M

    2000-10-01

    Full Text Available The term reflex epilepsy in reserved for a small subgroup o seizures that occur regularly in response to specific stimuli. Our patient is a 20- year old male, who had pleasure, euphoria, loss of conciousness and generalized tonic- clonic convulstion when he watched TV since ten years. During puberty the patient that self-induced reflex epilepsy with photic stimulation, when watching TV or looking at sun and with had moving in front of his eyes to produce flickers. The patient first had sex pleasure, euphoria, erection and ejaculation, and then developed loss of consiousness and generalized tonic- clonic seizure, that took about 4-5 min. what is more intersing is that he asked us for a kind of drug that controlled his generalized tonic-clonic seizures but not his pleasure and orgasm, and he said that he would refuse any drug interfered with his orgasm.

  15. Short latency stretch reflex in human lumbar paraspinal muscles.

    Science.gov (United States)

    Skotte, Jørgen; Hjortskov, Nis; Essendrop, Morten; Schibye, Bente; Fallentin, Niels

    2005-06-30

    The aim of the study was to measure stretch reflex latencies of the lumbar paraspinal muscles. An electromechanical tapping system was constructed enabling an accurate estimation of short latencies by utilizing a new technique combining results for different tapping durations. Latency parameters (onset, peak and zero-crossing of EMG signal) were obtained for the paraspinal muscles at the L3/L4 level for 10 male subjects. Detection of EMG onset, which was determined by a threshold criterion (2.5 S.D. of pre-activity), yielded 7.4+/-1.4 ms corresponding to a physiological short latency onset of 6.5 ms, which is considerably shorter than previously reported. However, it is shown to be consistent with the expected latency value for a monosynaptic stretch reflex for the paraspinal muscles of the low back.

  16. MODULATION OF DEFENSIVE REFLEX CONDITIONING IN SNAILS BY SEROTONIN

    Directory of Open Access Journals (Sweden)

    Vyatcheslav V Andrianov

    2015-10-01

    Full Text Available We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the neurotoxic analogues of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within two weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail’s ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3.

  17. Active maternal phenotype is established before breeding and leads offspring to align growth trajectory outcomes and reflex ontogeny.

    Science.gov (United States)

    Santana Muniz, Gisélia; Beserra, Renata; da Silva, Giselle de Paula; Fragoso, Jéssica; Lira, Allan de Oliveira; Nascimento, Elizabeth; Manhães de Castro, Raul; Leandro, Carol Góis

    2014-04-22

    The main goals of this study were to classify dams according to the level of voluntary physical activity before breeding and during pregnancy/lactation and to evaluate the effects on growth trajectory and reflex ontogenesis of offspring. Voluntary physical activity was ranked by traveled distance, time and daily estimated calorie burned. Thirty-five female Wistar rats were classified as control (C, n=5), inactive (I, n=10), active (A, n=8) and very active (VA, n=12). During 30d before breeding, traveled distance, average speed, time and calorie burned were daily recorded for active and very active groups. Traveled distance was recorded each 2h every day of adaptation. Body weight, food intake and fasting glycemia were measured throughout the experiment. During lactation, litters were evaluated in terms of physical features and reflex ontogeny. VA showed a progressive increase in the traveled distance and time while A dams presented constant values. VA rats showed lower body weight and higher food intake. During pregnancy, both groups performed less than 1km/day. Pups from A and VA dams showed higher lateral-lateral axis of the skull, longitudinal axis, tail length, and anticipation of the pavilion and auditory canal opening, and erupting incisors. I, A and VA groups showed a delay of righting, cliff aversion and vibrissae placing reflexes. In conclusion, active maternal phenotype is established before breeding allowing mothers to fit ecological and influencing growth trajectory outcomes and reflex ontogeny of the offspring based on matrilineal experience. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. The Mammalian Diving Response: An Enigmatic Reflex to Preserve Life?

    Science.gov (United States)

    2013-01-01

    The mammalian diving response is a remarkable behavior that overrides basic homeostatic reflexes. It is most studied in large aquatic mammals but is seen in all vertebrates. Pelagic mammals have developed several physiological adaptations to conserve intrinsic oxygen stores, but the apnea, bradycardia, and vasoconstriction is shared with those terrestrial and is neurally mediated. The adaptations of aquatic mammals are reviewed here as well as the neural control of cardiorespiratory physiology during diving in rodents. PMID:23997188

  19. Electrophysiological study of the bulbocavernosus reflex: normative data

    OpenAIRE

    Granata, Giuseppe; Padua, Luca; Rossi, Fabiana; Franco, Paola; Coraci,Daniele; Rossi, Vincenzo

    2014-01-01

    In the clinical setting the bulbocavernosus reflex (BCR) is elicited by squeezing the glans penis and digitally palpating the contraction of the bulbocavernosus (BC) muscle. In neurophysiology the BCR is obtained by stimulating the dorsal nerve of the penis or clitoris and by recording the response from BC muscle and it should be performed in selected patients with suspected urinary, bowel, or sexual neurogenic dysfunction. The BCR is considered one of the sacral neurophysiological tests of t...

  20. Stimulation of the corneal blinking reflex by ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tobias, C.; Luce, J.; Yanni, N.; Brustad, T.; Lyman, J.; Kimura, S.

    1961-05-04

    Accelerated alpha particles from the Berkeley heavy-ion linear accelerator were used in a series of experiments designed to elucidate the conditions by which radiation can stimulate or modify nerve action in mammals. Single millisecond pulses in excess of 40,000 radsor pulse trains of less than 1 sec duration elicited the corneal blinking reflex when delivered to the cornea of unanesthetized rabbits. The lowest threshold dose was observed when the Bragg ionization peak was placed at 140 {mu} depth.

  1. ESO Reflex: A Graphical Workflow Engine for Data Reduction

    Science.gov (United States)

    Hook, R.; Romaniello, M.; Péron, M.; Ballester, P.; Gabasch, A.; Izzo, C.; Ullgrén, M.; Maisala, S.; Oittinen, T.; Solin, O.; Savolainen, V.; Järveläinen, P.; Tyynelä, J.

    2008-08-01

    Sampo {http://www.eso.org/sampo} (Hook et al. 2005) is a project led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. The goal is to assess the needs of the ESO community in the area of data reduction environments and to create pilot software products that illustrate critical steps along the road to a new system. Those prototypes will not only be used to validate concepts and understand requirements but will also be tools of immediate value for the community. Most of the raw data produced by ESO instruments can be reduced using CPL {http://www.eso.org/cpl} recipes: compiled C programs following an ESO standard and utilizing routines provided by the Common Pipeline Library. Currently reduction recipes are run in batch mode as part of the data flow system to generate the input to the ESO VLT/VLTI quality control process and are also made public for external users. Sampo has developed a prototype application called ESO Reflex {http://www.eso.org/sampo/reflex/} that integrates a graphical user interface and existing data reduction algorithms. ESO Reflex can invoke CPL-based recipes in a flexible way through a dedicated interface. ESO Reflex is based on the graphical workflow engine Taverna {http://taverna.sourceforge.net} that was originally developed by the UK eScience community, mostly for work in the life sciences. Workflows have been created so far for three VLT/VLTI instrument modes ( VIMOS/IFU {http://www.eso.org/instruments/vimos/}, FORS spectroscopy {http://www.eso.org/instruments/fors/} and AMBER {http://www.eso.org/instruments/amber/}), and the easy-to-use GUI allows the user to make changes to these or create workflows of their own. Python scripts and IDL procedures can be easily brought into workflows and a variety of visualisation and display options, including custom product inspection and validation steps, are available.

  2. Genetic associations with reflexive visual attention in infancy and childhood.

    Science.gov (United States)

    Lundwall, Rebecca A; Dannemiller, James L; Goldsmith, H Hill

    2017-05-01

    This study elucidates genetic influences on reflexive (as opposed to sustained) attention in children (aged 9-16 years; N = 332) who previously participated as infants in visual attention studies using orienting to a moving bar (Dannemiller, 2004). We investigated genetic associations with reflexive attention measures in infancy and childhood in the same group of children. The genetic markers (single nucleotide polymorphisms and variable number tandem repeats on the genes APOE, BDNF, CHRNA4, COMT, DRD4, HTR4, IGF2, MAOA, SLC5A7, SLC6A3, and SNAP25) are related to brain development and/or to the availability of neurotransmitters such as acetylcholine, dopamine, or serotonin. This study shows that typically developing children have differences in reflexive attention associated with their genes, as we found in adults (Lundwall, Guo & Dannemiller, 2012). This effort to extend our previous findings to outcomes in infancy and childhood was necessary because genetic influence may differ over the course of development. Although two of the genes that were tested in our adult study (Lundwall et al., 2012) were significant in either our infant study (SLC6A3) or child study (DRD4), the specific markers tested differed. Performance on the infant task was associated with SLC6A3. In addition, several genetic associations with an analogous child task occurred with markers on CHRNA4, COMT, and DRD4. Interestingly, the child version of the task involved an interaction such that which genotype group performed poorer on the child task depended on whether we were examining the higher or lower infant scoring group. These findings are discussed in terms of genetic influences on reflexive attention in infancy and childhood. © 2015 John Wiley & Sons Ltd.

  3. Blink Reflex May Help Discriminate Alzheimer Disease From Vascular Dementia.

    Science.gov (United States)

    Mohammadian, Fatemeh; Noroozian, Maryam; Nafissi, Shahriar; Fatehi, Farzad

    2015-12-01

    Dementia has several different etiologies, and vascular dementia (VaD) is considered the second leading cause of dementia after Alzheimer disease (AD). Various studies used blink reflex in different spectrum of neurological diseases as a complementary diagnostic test. We performed blink test in AD, VaD, and mixed dementia to investigate different usefulness of blink reflex in differentiating these types of dementia. Blink reflex was performed for patients with AD (n = 18), VaD (n = 17), mixed dementia (n = 19), and normal subjects (n = 20). The absolute latency of R1, R2, and contralateral R2 (R2c) was determined and then compared with normal values. We used ROC curve to determine the screening cut-off value for R2 and R2c to discriminate dementia with vascular component and AD. The mean age ± SD of patients was 71.61 ± 8.23, 66.71 ± 11.48, 75.26 ± 8.32, and 66.60 ± 3.91 years in 4 groups of AD, VaD, mixed dementia, and normal, respectively. R2 and R2c were recorded in fewer number of subjects with VaD or mixed dementia than AD and normal subjects. For mean R2 latency higher than 45 milliseconds, the sensitivity and specificity were 42% and 100%, respectively, and for latency higher than 45 milliseconds, the sensitivity and specificity were 72% and 89%, respectively. R2 and R2c components of blink reflex could specifically discriminate between Alzheimer and dementia with vascular component. The interruption of descending corticoreticular pathways by small infarcts could explain it.

  4. HPLC analysis of closed, open, and reflex eye tear proteins

    OpenAIRE

    Sitaramamma T; Shivaji S; Rao Gullapalli

    1998-01-01

    Changes in the closed, open and reflex eye tear proteins of normal subjects were compared and analysed. Tear proteins were resolved by high-performance liquid chromatography (HPLC) utilising both gel filtration (P-300 SW) and reverse-phase (C-18) columns and the HPLC fractions were further analysed by sodium dodecyl sulphate - polyacrylamide gel electrophoresis (SDS-PAGE) under reducing and non-reducing conditions. The protein composition of the closed-eye tear was significantly different fro...

  5. Priming Neural Circuits to Modulate Spinal Reflex Excitability

    OpenAIRE

    Estes, Stephen P.; Iddings, Jennifer A.; Field-Fote, Edelle C.

    2017-01-01

    While priming is most often thought of as a strategy for modulating neural excitability to facilitate voluntary motor control, priming stimulation can also be utilized to target spinal reflex excitability. In this application, priming can be used to modulate the involuntary motor output that often follows central nervous system injury. Individuals with spinal cord injury (SCI) often experience spasticity, for which antispasmodic medications are the most common treatment. Physical therapeutic/...

  6. Reflex penile erection in anesthetized mice: an exploratory study.

    Science.gov (United States)

    Allard, J; Edmunds, N J

    2008-07-31

    Ejaculatory-like rhythmic contractions of the bulbospongiosus (BS) muscle and penile erection can be elicited in the urethane-anesthetized rat, following spinal cord transection, upon electrical stimulation (ES) of the dorsal penile nerve (DPN). The aim of this work was to investigate this reflex in anesthetized mice. Adult C57BL6 mice were anesthetized with isoflurane. The BS muscle and corpus cavernosum were instrumented to allow quantification of the BS muscle electromyographic activity (BS EMG) and intracavernosal pressure respectively. The femoral artery and jugular vein were catheterized to allow measurement of blood pressure and compound administration. ES of the DPN, via bipolar silver electrodes, reliably evoked erectile responses in mice with intact spinal cords. The overall amplitude of the erectile response was frequency- and pulse duration-dependent. Erectile responses were abolished by bilateral cut of the sensory branch of the pudendal nerve. Transection of the spinal cord potentiated the erectile responses and increased the area under the curve of the BS EMG when compared with those animals with intact spinal cords. However, no coordinated rhythmic contractions of the BS muscle during or after the ES could be observed, with or without spinal transection. Melanotan-II failed to enhance the erectile response induced by ES of the DPN, in mice with intact spinal cords. ES of the DPN in isoflurane-anesthetized mice could be a useful model in which to study the interplay between brain and spinal cord in the control of reflex penile erection, and could take advantage of knockout mice models. However, the lack of efficacy of Melanotan-II suggests that further experiments are necessary to confirm the future utility of this model. In contrast to rats, the expulsion reflex could not be reliably elicited in mice with or without spinal transection. This latter finding suggests the existence of fundamental differences in the organization of the spinal network

  7. Eye gaze triggers reflexive attention shifts: evidence from lateralised ERPs.

    Science.gov (United States)

    Feng, Qing; Zhang, Xuemin

    2014-11-17

    Social cues, such as another individual׳s eye gaze, provide valuable information regarding the actions and intentions of others. Previous studies have suggested that seeing another׳s gaze automatically orients one׳s attention in the gaze direction. In this event-related potential (ERP) study, a spatial cuing paradigm was combined with a visual search task in which targets were defined by feature conjunctions in order to eliminate effects of target/distractor salience. Participants viewed centrally presented faces with neutral expressions in which eyes looked to the left or right. The participants׳ task was to identify a target object (with or without gap) defined by a combination of shape and orientation, which appeared in either the same (cued) or the opposite (uncued) location as the direction of the eye gaze. There was behavioural evidence of a gaze congruency effect, as reaction times (RTs) were faster when the eyes looked towards the target rather than away from the location of the target. The ERP data indicated the presence of significant gaze-congruent early directing attention negativity (EDAN) and anterior directing attention negativity (ADAN), reflecting attention shifts to the cued location in advance of the target presentation. ERP data did not show evidence of later orienting of attention triggered by gaze cues in the late attention-directing attention positivity (LDAP) at posterior sites. The results disclosed the neural response during reflexive attention shifting triggered by gazes and ascertained the relationship among EDAN, ADAN, LDAP and gaze-elicited attention shifts. After the presentation of the target array without salient stimuli, the presence of the N2-posterior-contralateral (N2pc) in the cued trials and the absence in the uncued trials further supported that attention had been directed to the possible target location prior to the target onset. The ERPs in response to the target array also extend our understanding of the neural

  8. Effect of betel nut chewing on the otolithic reflex system.

    Science.gov (United States)

    Lin, Chuan-Yi; Young, Yi-Ho

    2017-01-01

    This study investigated the effect of betel nut chewing on the otolithic reflex system. Seventeen healthy volunteers without any experience of chewing betel nut (fresh chewers) and 17 habitual chewers underwent vital sign measurements, ocular vestibular-evoked myogenic potential (oVEMP), and cervical VEMP (cVEMP) tests prior to the study. Each subject then chewed two pieces of betel nut for 2min (dosing). The same paradigm was repeated immediately, 10min, and 20min after chewing. On a different day, 10 fresh chewers masticated chewing gum as control. Fresh chewers exhibited significantly decreased response rates of oVEMP (53%) and cVEMP (71%) after dosing compared with those from the predosing period. These abnormal VEMPs returned to normal 20min after dosing. In contrast, 100% response rates of oVEMP and cVEMP were observed before and after masticating chewing gum. In habitual chewers, the response rates of oVEMP and cVEMP were 32% and 29%, respectively, 20min after dosing. Chewing betel nuts induced a transient loss of the otolithic reflexes in fresh chewers but may cause permanent loss in habitual chewers. Chewing betel nuts can cause a loss of otholitic reflex function. This creates a risk for disturbed balance and malfunction, for instance, during driving. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  9. Primitive reflexes in amyotrophic lateral sclerosis: prevalence and correlates.

    Science.gov (United States)

    Tremolizzo, Lucio; Susani, Emanuela; Lunetta, Christian; Corbo, Massimo; Ferrarese, Carlo; Appollonio, Ildebrando

    2014-06-01

    Identifying frontal impairment in ALS is an important goal albeit disease-dedicated tools are still scarce. For this reason, we decided to consider primitive reflexes (PRs), variably regarded as correlates of frontal release and/or of upper motor neuron (UMN) impairment, often in the setting of dementias. Specifically, the aims of this work consisted in assessing the exact prevalence of the combination of seven PRs in ALS, trying to clarify their role as putative proxies of cognitive impairment or of UMN dysfunction. In this cross-sectional study, 50 consecutive ALS outpatients were evaluated for the presence of: palmomental (PM), corneomandibular (CM), glabella tap (MY), rooting, sucking, snout, and grasping reflexes. Cognitive screening was performed by the Frontal Assessment Battery (FAB) and the Weigl's Sorting test (WST); UMN dysfunction was concomitantly evaluated. PM, CM and MY were more frequently detected (62, 52, and 44 % of the ALS sample, respectively), while the other reflexes were under-represented. Patients displaying three or more PRs had significantly lower FAB and WST scores. On the other hand, UMN dysfunction was only moderately associated to PRs. In conclusion, PRs' assessment is a promising complementary tool for screening cognitive impairment in ALS; however, further work will be necessary to establish its added value with respect to already existing ALS-dedicated screening tools for cognition.

  10. Modulation of defensive reflex conditioning in snails by serotonin

    Science.gov (United States)

    Andrianov, Vyatcheslav V.; Bogodvid, Tatiana K.; Deryabina, Irina B.; Golovchenko, Aleksandra N.; Muranova, Lyudmila N.; Tagirova, Roza R.; Vinarskaya, Aliya K.; Gainutdinov, Khalil L.

    2015-01-01

    Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the “neurotoxic” analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the “neurotoxic” analogs of serotonin 5,6- and 5,7-dihydroxytryptamine as well as serotonin, depolarization of the membrane and decrease of the threshold potential of premotor interneurons was observed. We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the “neurotoxic” analogs of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT) were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within 2 weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail's ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3. PMID:26557063

  11. Reflex epilepsy induced by playing oriental card or board games.

    Science.gov (United States)

    Lee, Sang Ahm; Choi, Eun Jung; Kang, Joong Koo

    2006-12-01

    There are currently few studies on clinical profiles of reflex epilepsy induced by thinking and spatial tasks. We studied the clinical characteristics of reflex epilepsy induced by playing oriental card and board games. This study included 17 patients who presented with seizures that occur predominantly while playing games. We collected clinical data via protocol-based interviews. EEGs and brain MRI were performed. All of the subjects were men, and all of them were older than 30 years at the onset of seizure. Thirteen patients (76%) experienced their seizures while playing the oriental card game "Go-stop" and the remaining four patients (24%) experienced them while playing the oriental board game "Baduk". Generalized tonic-clonic seizures were frequently preceded by prodromal symptoms, but myoclonus was not evident. Most patients had no spontaneous seizures and generalized epileptiform discharges on EEGs, and infrequent seizures that were well controlled. Our patients exhibited some features that differ from those described previously in the literature, suggesting that the clinical spectrum of reflex epilepsy induced by thinking and spatial tasks is wide.

  12. A reflexive exploration of two qualitative data coding techniques

    Directory of Open Access Journals (Sweden)

    Erik Blair

    2016-01-01

    Full Text Available In an attempt to help find meaning within qualitative data, researchers commonly start by coding their data. There are a number of coding systems available to researchers and this reflexive account explores my reflections on the use of two such techniques. As part of a larger investigation, two pilot studies were undertaken as a means to examine the relative merits of open coding and template coding for examining transcripts. This article does not describe the research project per se but attempts to step back and offer a reflexive account of the development of data coding tools. Here I reflect upon and evaluate the two data coding techniques that were piloted, and discuss how using appropriate aspects of both led to the development of my final data coding approach. My exploration found there was no clear-cut ‘best’ option but that the data coding techniques needed to be reflexively-aligned to meet the specific needs of my project. This reflection suggests that, when coding qualitative data, researchers should be methodologically thoughtful when they attempt to apply any data coding technique; that they do not assume pre-established tools are aligned to their particular paradigm; and that they consider combining and refining established techniques as a means to define their own specific codes. DOI: 10.2458/azu_jmmss.v6i1.18772DOI: 10.2458/azu_jmmss.v6i1.18772

  13. Trait dominance promotes reflexive staring at masked angry body postures.

    Directory of Open Access Journals (Sweden)

    Ruud Hortensius

    Full Text Available It has been shown that dominant individuals sustain eye-contact when non-consciously confronted with angry faces, suggesting reflexive mechanisms underlying dominance behaviors. However, dominance and submission can be conveyed and provoked by means of not only facial but also bodily features. So far few studies have investigated the interplay of body postures with personality traits and behavior, despite the biological relevance and ecological validity of these postures. Here we investigate whether non-conscious exposure to bodily expressions of anger evokes reflex-like dominance behavior. In an interactive eye-tracking experiment thirty-two participants completed three social dominance tasks with angry, happy and neutral facial, bodily and face and body compound expressions that were masked from consciousness. We confirmed our predictions of slower gaze-aversion from both non-conscious bodily and compound expressions of anger compared to happiness in high dominant individuals. Results from a follow-up experiment suggest that the dominance behavior triggered by exposure to bodily anger occurs with basic detection of the category, but not recognition of the emotional content. Together these results suggest that dominant staring behavior is reflexively driven by non-conscious perception of the emotional content and triggered by not only facial but also bodily expression of anger.

  14. The articulo-cardiac sympathetic reflex in spinalized, anesthetized rats.

    Science.gov (United States)

    Nakayama, Tomohiro; Suzuki, Atsuko; Ito, Ryuzo

    2006-04-01

    Somatic afferent regulation of heart rate by noxious knee joint stimulation has been proven in anesthetized cats to be a reflex response whose reflex center is in the brain and whose efferent arc is a cardiac sympathetic nerve. In the present study we examined whether articular stimulation could influence heart rate by this efferent sympathetic pathway in spinalized rats. In central nervous system (CNS)-intact rats, noxious articular movement of either the knee or elbow joint resulted in an increase in cardiac sympathetic nerve activity and heart rate. However, although in acutely spinalized rats a noxious movement of the elbow joint resulted in a significant increase in cardiac sympathetic nerve activity and heart rate, a noxious movement of the knee joint had no such effect and resulted in only a marginal increase in heart rate. Because this marginal increase was abolished by adrenalectomy suggests that it was due to the release of adrenal catecholamines. In conclusion, the spinal cord appears to be capable of mediating, by way of cardiac sympathetic nerves, the propriospinally induced reflex increase in heart rate that follows noxious stimulation of the elbow joint, but not the knee joint.

  15. Active head rotation in benign positional paroxysmal vertigo Da rotação cefálica ativa na vertigem posicional paroxística benigna

    Directory of Open Access Journals (Sweden)

    Fernando Freitas Ganança

    2009-08-01

    Full Text Available Benign Positional Paroxysmal Vertigo (BPPV is one of the most common vestibular diseases and the active head rotation test one of the most modern methods of vestibular function assessment. AIM: this study aims to verify if the active head rotation test may reveal signs of horizontal and/or vertical vestibulo-ocular reflex dysfunction in vertigo patients suspected for BPPV. STUDY DESIGN: retrospective series study. MATERIALS AND METHOD: Neurotological evaluation including computerized electronystagmography and active head rotation on the horizontal and vertical axes were conducted in 100 patients suspected for BPPV patients. Results: Isolated or associated abnormalities of the horizontal and/or vertical vestibulo-ocular reflex gain, phase and symmetry were indicative of vestibular involvement and found in 77.0% of the BPPV patients. CONCLUSION: the active head rotation test revealed horizontal and/or vertical vestibulo-ocular reflex dysfunctions in a relevant number of BPPV patients.A vertigem posicional paroxística benigna (VPPB corresponde a uma das vestibulopatias mais comuns e a rotação cefálica ativa um dos métodos mais modernos de avaliação da função vestibular. OBJETIVO: O objetivo desta pesquisa foi verificar se a prova de rotação cefálica ativa pode revelar sinais de disfunção do reflexo vestíbulo-ocular horizontal e/ou vertical em pacientes vertiginosos com hipótese diagnóstica de VPPB. DESENHO DO ESTUDO: Estudo de série retrospectivo. MATERIAL E MÉTODO: Uma avaliação otoneurológica incluindo a eletronistagmografia computadorizada e a prova de rotação cefálica ativa, no plano horizontal e vertical foi conduzida em 100 pacientes com hipótese diagnóstica de VPPB. Resultados: Alterações isoladas ou associadas de ganho, fase e assimetria do reflexo vestíbulo-ocular horizontal e/ou vertical, foram os achados indicativos de comprometimento vestibular em 77,0% dos casos de VPPB. CONCLUSÃO: A prova de rota

  16. Electrical stimulation of the dorsal nerve of the penis evokes reflex tonic erections of the penile body and reflex ejaculatory responses in the spinal rat.

    Science.gov (United States)

    Pescatori, E S; Calabro, A; Artibani, W; Pagano, F; Triban, C; Italiano, G

    1993-03-01

    An animal model using the spinal rat was characterized. Electrical stimulation of the dorsal nerve of the penis elicited reflex tonic erections of the penile body and reflex bulbospongiosus muscle activity, flips and ejaculations. The tonic erections of the penile body are independent from contractions of the bulbospongiosus muscle and appear to be the result of a neurovascular process. Our observations suggest that reflex bulbospongiosus muscle activity, flips and ejaculations are a single complex reflex response, which we define as reflex ejaculatory response. Two parameters predicted the occurrence and type of reflex response. The visualization of bulbospongiosus muscle activity during surgical isolation of the dorsal nerve of the penis was sufficient to anticipate the elicitability of reflex ejaculatory responses. The latter, together with a systemic systolic pressure > or = 73 mmHg., warranted the elicitability of reflex tonic erections. The similarities found in the physiology of rat tonic penile body erections and of human erections make this model promising for further elucidation of sexual function. Moreover, the present model may prove useful for the investigation of neurogenic erectile dysfunction, and of neurogenic ejaculatory disorders.

  17. Correlation of augmented startle reflex with brainstem electrophysiological responses in Tay-Sachs disease.

    Science.gov (United States)

    Nakamura, Sadao; Saito, Yoshiaki; Ishiyama, Akihiko; Sugai, Kenji; Iso, Takashi; Inagaki, Masumi; Sasaki, Masayuki

    2015-01-01

    To clarify the evolution of an augmented startle reflex in Tay-Sachs disease and compare the temporal relationship between this reflex and brainstem evoked potentials. Clinical and electrophysiological data from 3 patients with Tay-Sachs disease were retrospectively collected. The augmented startle reflex appeared between the age of 3 and 17 months and disappeared between the age of 4 and 6 years. Analysis of brainstem auditory evoked potentials revealed that poor segregation of peak I, but not peak III, coincided with the disappearance of the augmented startle reflex. A blink reflex with markedly high amplitude was observed in a patient with an augmented startle reflex. The correlation between the augmented startle reflex and the preservation of peak I but not peak III supports the theory that the superior olivary nucleus is dispensable for this reflex. The blink reflex with high amplitudes may represent augmented excitability of reticular formation at the pontine tegmentum in Tay-Sachs disease, where the pattern generators for the augmented startle and blink reflexes may functionally overlap. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  18. The Closing of Critique, Pluralism and Reflexivity

    DEFF Research Database (Denmark)

    Alvesson, Mats; Kärreman, Dan

    2013-01-01

    assumptions and be unwelcome to critical explorations. The article points to the risk of assumption-challenging work being marginalized through the anticipation of critique leading to hostile reactions and specialized, politically motivated reviewers blocking the publication of far-reaching critique.......This article is a follow-up of Alvesson and Kärreman (2011a), which was in itself a follow-up of Alvesson and Kärreman (2000), and a response to a critique of the former by Hardy and Grant (2012). The critique is addressed directly and the logic behind it investigated critically. The article also...... addresses wider concerns regarding the politics of research and publishing and the conditions of critique at the present time. The pressure and eagerness to get published lead to strong subspecialization and an inclination to build research approaches within which authors are inclined to reproduce shared...

  19. Reliability of the Achilles tendon tap reflex evoked during stance using a pendulum hammer.

    Science.gov (United States)

    Mildren, Robyn L; Zaback, Martin; Adkin, Allan L; Frank, James S; Bent, Leah R

    2016-01-01

    The tendon tap reflex (T-reflex) is often evoked in relaxed muscles to assess spinal reflex circuitry. Factors contributing to reflex excitability are modulated to accommodate specific postural demands. Thus, there is a need to be able to assess this reflex in a state where spinal reflex circuitry is engaged in maintaining posture. The aim of this study was to determine whether a pendulum hammer could provide controlled stimuli to the Achilles tendon and evoke reliable muscle responses during normal stance. A second aim was to establish appropriate stimulus parameters for experimental use. Fifteen healthy young adults stood on a forceplate while taps were applied to the Achilles tendon under conditions in which postural sway was constrained (by providing centre of pressure feedback) or unconstrained (no feedback) from an invariant release angle (50°). Twelve participants repeated this testing approximately six months later. Within one experimental session, tap force and T-reflex amplitude were found to be reliable regardless of whether postural sway was constrained (tap force ICC=0.982; T-reflex ICC=0.979) or unconstrained (tap force ICC=0.968; T-reflex ICC=0.964). T-reflex amplitude was also reliable between experimental sessions (constrained ICC=0.894; unconstrained ICC=0.890). When a T-reflex recruitment curve was constructed, optimal mid-range responses were observed using a 50° release angle. These results demonstrate that reliable Achilles T-reflexes can be evoked in standing participants without the need to constrain posture. The pendulum hammer provides a simple method to allow researchers and clinicians to gather information about reflex circuitry in a state where it is involved in postural control. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Failure in evoking the trigeminal cardiac reflex by mandibular stretching in healthy volunteers.

    Science.gov (United States)

    De Innocentiis, Carlo; Caputi, Cristiano Giovannni; Pinto, Filomena; Quintiliani, Stefania; Meccariello, Armando; Renda, Giulia; Di Nicola, Marta; De Caterina, Raffaele; D'Attilio, Michele

    2015-03-01

    Stimulation of trigeminal sensory afferences has been reported to evoke hypotension and bradycardia, a phenomenon known as the trigeminal cardiac reflex. We attempted to evoke such a reflex through cycles of alternate mandibular stretching in healthy volunteers, as previously reported, for its possible therapeutic exploitation. In Phase 1 of the study, 10 healthy volunteers [5 male, 5 female, age (mean ± SD) 27±2 years)] underwent 2 randomized sessions of automated monitoring, every 6 minutes, of systolic blood pressure (SBP), diastolic (D) BP, and heart rate (HR), with a one-week interval, either with mandibular stretching (12 minutes with a spring device fitted in the mouth), or nothing (control). Observation was prolonged for 180 minute after the end of the stretching. In Phase 2, 7 other volunteers (4 male and 3 female, age 24±1.3 years) repeated the protocol with a sampling interval of 2 minutes until the end of stretching. Baseline levels of SBP, DBP and HR were similar in the test and control sessions. There was a progressive fall of BP and HR as a function of time during the test session. With stretching: SBP changed from 119.2±10.1 to 118.1±10.1 to 115.8±10.5 mmHg, at baseline, end of stretching and 180 minutes after, respectively, pmeasurements, we could not detect significant BP or HR effects of repeated mandibular stretching.

  1. Acoustic stapedius muscle reflex in mercury-exposed Andean children and adults.

    Science.gov (United States)

    Counter, S Allen; Buchanan, Leo H; Ortega, Fernando

    2012-01-01

    The results suggested mercury (Hg)-induced anomalies in the brainstem-mediated acoustic stapedius muscle reflex in children. Hg exposure has been associated with hearing impairment and brainstem anomalies. Acoustic stapedius reflex (ASR) thresholds, growth functions, decay/adaptation times, and behavioral auditory thresholds were used to screen Andean children and adults for Hg-induced auditory brainstem and facial nerve impairment. Fifty-one participants, which included 22 children (aged 6-17 years) and 29 adults (aged 19-83 years) living in gold mining areas of Ecuador where Hg is widely used in amalgamation, were screened using ASR immittance procedures. Mean blood mercury (HgB) level in the children was 15.6 μg/L (SD, 21.3; median, 7 μg/L; range, 2.0-89 μg/L), and in the adults 8.5 μg/L (SD, 7.1; median, 6 μg/L; range, 2.0-32 μg/L). Mean contralateral ASR thresholds (ASRT) for the screening frequency of 2000 Hz in the children (39 ears) was 92.9 dB HL (SD, 6.1; range, 80-105 dB HL), and in the adults (53 ears) 90.0 dB HL (SD, 6.4; range, 65-105 dB HL). The ASRT in the children increased significantly with HgB level (rho = 0.433; p = 0.008).

  2. The Use of an Alternative Extraoral Periapical Technique for Patients with Severe Gag Reflex

    Directory of Open Access Journals (Sweden)

    Mauro Henrique Chagas e Silva

    2016-01-01

    Full Text Available Gag reflex is a physiologic mechanism that promotes contraction of the muscles of the tongue and pharyngeal walls. Different factors, including intraoral radiographic films and sensors, may trigger this reflex. Patients with severe gag reflex may not be able to tolerate the presence of intraoral radiographic films or sensors during root canal therapy (RCT. This factor may prevent an appropriate intraoral radiograph, which is important in RCT. Different approaches have been used to facilitate dental procedures in patients suffering from severe gag reflex. The use of an extraoral radiographic technique is an alternative method to obtain working length confirmation in patients with severe gag reflex. In this report of 2 cases, the use of an extraoral radiographic technique as an alternative approach during RCT in patients with severe gag reflex associated with phobic behavior and trismus was successfully demonstrated.

  3. Trigeminal sensory neuropathy associated with decreased oral sensation and impairment of the masseter inhibitory reflex.

    Science.gov (United States)

    Auger, R G; McManis, P G

    1990-05-01

    We describe 4 patients with severe trigeminal sensory neuropathy whose main disability resulted from impaired intraoral sensation associated with disturbances of mastication and swallowing. Each patient had an abnormal blink reflex and jaw jerk. In addition, the masseter inhibitory reflex was absent in 3 patients and abnormal in the 4th. This reflex plays a role in the reflex control of mastication and can easily be elicited in normal subjects by stimulation of the skin and mucous membrane in the distribution of the 2nd and 3rd divisions of the trigeminal nerve while the jaw-closing muscles are contracting. Disturbed intraoral sensation combined with impaired trigeminal reflexes (particularly the masseter inhibitory reflex) interferes with neural mechanisms that regulate chewing and can be a source of severe disability in patients with trigeminal sensory neuropathy.

  4. Changes of reflex size in upper limbs using wrist splint in hemiplegic patients.

    Science.gov (United States)

    Ushiba, J; Masakado, Y; Komune, Y; Muraoka, Y; Chino, N; Tomita, Y

    2004-01-01

    We evaluated the effect of prolonged wrist extension on H reflex in the flexor carpi radialis (FCR) muscle and tendon jerk (T) reflex in the biceps brachii (BB) muscle of 17 chronic hemiplegic patients. H reflex of the FCR and T reflex of the BB were assessed every 5 minutes within 20 minutes during prolonged wrist extension and post-20 minutes after the extension. As a result, H reflex in the FCR was reduced by passive wrist stretch in 82% of the spastic limbs. The effect was larger in the higher spastic group. In 45% of the spastic limbs, T reflex in the BB also was reduced by passive wrist stretch. The inhibitory effects had a tendency to strengthen in accordance with the grade of muscle tone. We considered from these results, prolonged wrist extension generated inhibitory projections via probably group II afferents of the FCR in the homonym and in the transjoint in spastic limbs.

  5. The Gateway Reflex, a Novel Neuro-Immune Interaction for the Regulation of Regional Vessels.

    Science.gov (United States)

    Tanaka, Yuki; Arima, Yasunobu; Kamimura, Daisuke; Murakami, Masaaki

    2017-01-01

    The gateway reflex is a new phenomenon that explains how immune cells bypass the blood-brain barrier to infiltrate the central nervous system (CNS) and trigger neuroinflammation. To date, four examples of gateway reflexes have been discovered, each described by the stimulus that evokes the reflex. Gravity, electricity, pain, and stress have all been found to create gateways at specific regions of the CNS. The gateway reflex, the most recently discovered of the four, has also been shown to upset the homeostasis of organs in the periphery through its action on the CNS. These reflexes provide novel therapeutic targets for the control of local neuroinflammation and organ function. Each gateway reflex is activated by different neural activations and induces inflmammation at different regions in the CNS. Therefore, it is theoretically possible to manipulate each independently, providing a novel therapeutic strategy to control local neuroinflammation and peripheral organ homeostasis.

  6. Nociception specific supraorbital nerve stimulation may prevent cluster headache attacks: serendipity in a blink reflex study.

    Science.gov (United States)

    Haane, Danielle Y P; Koehler, Peter J

    2014-10-01

    In cluster headache, neuromodulation is offered when patients are refractory to pharmacological prophylaxis. Non-invasive peripheral neuromodulatory approaches are of interest. We will focus on these and particularly on nociception specific, transcutaneous supraorbital nerve stimulation. In a study using the nociception specific blink reflex, we made a serendipitous discovery, notably the potential prophylactic effect of bilateral, time contingent, nociception specific, transcutaneous stimulation of the supraorbital nerve. We report on a case series of seven cluster headache patients, in whom attacks seemed to disappear during repeated stimulation of the supraorbital nerves. Three patients stopped experiencing attacks since study participation. Bilateral, time contingent, nociception specific, transcutaneous supraorbital nerve stimulation may have a prophylactic effect in episodic and chronic cluster headache. Given its limited side effects and its non-invasive nature, further studies to investigate this potential peripheral neuromodulatory approach for both episodic and chronic cluster headache are warranted. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  7. The dynamics of interaction of reflexive subjects operating with the two-valued versus many-valued logic.

    Science.gov (United States)

    Sawa, Koji; Igamberdiev, Abir U

    2017-12-01

    In this paper we aim to approach a model of interacting subjects with the opposite types of reflexion that belong to the Western (W) and Eastern (E) reflexive modes according to Vladimir Lefebvre (1992). The model represents an expansion of the previously developed model of the Double Homunculus (Sawa and Igamberdiev, 2016) that describes reflexive agents as holding "the image of the self in the image of the self". A dialogue model between the two homunculus agents estimating their own reflexion in the opposite ways (generating the two-valued versus many-valued logic and loosely approximated as belonging to the W and E Lefebvre's types) is evolved. At the same time, the argument also unveils the relationship between a difference equation which is the key notion of the model and an emergence of logic. This can be a powerful tool for describing intercommunication of reflexive agents in the social environment as well as interactions between the entire social systems of different types. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The Polaroid and the Cross. Media-Reflexivity and Allegorical Figurations in Lucian Pintilie’s The Oak (1992

    Directory of Open Access Journals (Sweden)

    Sándor Katalin

    2016-09-01

    Full Text Available The paper discusses the question of media reflexivity and allegorical figuration in Lucian Pintilie’s 1992 film, The Oak. Through a fictional narrative, the film reflects on the communist period from the historical context of the post-1989 transition strongly marked by the after-effects of dictatorship and by political, social and economic instability. By incorporating a diegetic Polaroid camera and a home movie, The Oak displays a reflexive preoccupation with the mediality and the socio-cultural constructedness of the image. The figurative, allegorizing tendency of the film – manifest in the subversive recontextualization of grand narratives, iconographic codes or images of art history – also foregrounds the question of cultural mediation. I argue that by displaying the non-transparency of the cinematic image and the cultural mediatedness of the “real,” the media-reflexive and allegorical-figurative discourse of the film can be regarded as a critical historical response to the social and representational crises linked to the communist era, but at the same time it may be symptomatic of the social, cultural, political anxieties of post-1989 transition.1

  9. Effect of joint mobilization on the H Reflex amplitude in people with spasticity

    OpenAIRE

    Pérez Parra, Julio Ernesto; Henao Lema, Claudia Patricia

    2011-01-01

    Objective: To determine the effect of ankle joint mobilization on the H reflex amplitude of thesoleus muscle in people with spasticity. Materials and methods: A quasi-experimental study withcrossover design and simple masking was conducted in 24 randomized subjects to initiate thecontrol or experimental group. Traction and rhythmic oscillation were applied for five minutesto the ankle joint. H wave amplitude changes of Hoffmann reflex (electrical equivalent of themonosynaptic spinal reflex) w...

  10. Deprivation and Recovery of Sleep in Succession Enhances Reflexive Motor Behavior

    OpenAIRE

    Sprenger, Andreas; Weber, Frederik D.; Machner, Bjoern; Talamo, Silke; Scheffelmeier, Sabine; Bethke, Judith; Helmchen, Christoph; Gais, Steffen; Kimmig, Hubert; Born, Jan

    2015-01-01

    Sleep deprivation impairs inhibitory control over reflexive behavior, and this impairment is commonly assumed to dissipate after recovery sleep. Contrary to this belief, here we show that fast reflexive behaviors, when practiced during sleep deprivation, is consolidated across recovery sleep and, thereby, becomes preserved. As a model for the study of sleep effects on prefrontal cortex-mediated inhibitory control in humans, we examined reflexive saccadic eye movements (express saccades), as w...

  11. An educators’ perspective on reflexive pedagogy:identity undoing and issues of power

    OpenAIRE

    Iszatt-White, Marian; Kempster, Stephen John; Carroll, Brigid

    2017-01-01

    This article looks at reflexive pedagogical practice and the ‘identity undoing’ that such practice demands from educators. Such identity undoing is found to have strong connections to the impact on identity of power relations, resistance and struggle. A dialogic ‘testimonio’ approach is adopted tracing two of the authors’ experiences of attempting to introduce a reflexive pedagogy within a structured, accredited learning intervention. This approach analyses educators’ own reflexive dialogue t...

  12. Sympathetic ?-adrenergic mechanism in pudendal inhibition of nociceptive and non-nociceptive reflex bladder activity

    OpenAIRE

    Kadow, Brian T.; Lyon, Timothy D.; ZHANG, ZHAOCUN; Lamm, Vladimir; Shen, Bing; Wang, Jicheng; Roppolo, James R.; de Groat, William C.; Tai, Changfeng

    2016-01-01

    This study investigated the role of the hypogastric nerve and ?-adrenergic mechanisms in the inhibition of nociceptive and non-nociceptive reflex bladder activity induced by pudendal nerve stimulation (PNS). In ?-chloralose-anesthetized cats, non-nociceptive reflex bladder activity was induced by slowly infusing saline into the bladder, whereas nociceptive reflex bladder activity was induced by replacing saline with 0.25% acetic acid (AA) to irritate the bladder. PNS was applied at multiple t...

  13. VizieR Online Data Catalog: RefleX : X-ray-tracing code (Paltani+, 2017)

    Science.gov (United States)

    Paltani, S.; Ricci, C.

    2017-11-01

    We provide here the RefleX executable, for both Linux and MacOSX, together with the User Manual and example script file and output file Running (for instance): reflex_linux will produce the file reflex.out Note that the results may differ slightly depending on the OS, because of slight differences in some implementations numerical computations. The difference are scientifically meaningless. (5 data files).

  14. Reflex control of the spine and posture: a review of the literature from a chiropractic perspective

    OpenAIRE

    Schlappi Mark; Schlappi Heidi; Pettibon Burl R; Morningstar Mark W; Ireland Trevor V

    2005-01-01

    Abstract Objective This review details the anatomy and interactions of the postural and somatosensory reflexes. We attempt to identify the important role the nervous system plays in maintaining reflex control of the spine and posture. We also review, illustrate, and discuss how the human vertebral column develops, functions, and adapts to Earth's gravity in an upright position. We identify functional characteristics of the postural reflexes by reporting previous observations of subjects durin...

  15. Simultaneous characterizations of reflex and nonreflex dynamic and static changes in spastic hemiparesis.

    Science.gov (United States)

    Zhang, Li-Qun; Chung, Sun G; Ren, Yupeng; Liu, Lin; Roth, Elliot J; Rymer, W Zev

    2013-07-01

    This study characterizes tonic and phasic stretch reflex and stiffness and viscosity changes associated with spastic hemiparesis. Perturbations were applied to the ankle of 27 hemiparetic and 36 healthy subjects under relaxed or active contracting conditions. A nonlinear delay differential equation model characterized phasic and tonic stretch reflex gains, elastic stiffness, and viscous damping. Tendon reflex was characterized with reflex gain and threshold. Reflexively, tonic reflex gain was increased in spastic ankles at rest (P stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction (P stretch reflex especially in more spastic plantar flexors, which showed higher phasic stretch reflex gain than dorsi-flexors (P < 0.032). Spasticity was associated with increased tendon reflex gain (P = 0.002) and decreased threshold (P < 0.001). Mechanically, stiffness in spastic ankles was higher than that in controls across plantar flexion/dorsi-flexion torque levels (P < 0.032), and the more spastic plantar flexors were stiffer than dorsi-flexors at comparable torques (P < 0.031). Increased stiffness in spastic ankles was mainly due to passive stiffness increase (P < 0.001), indicating increased connective tissues/shortened fascicles. Viscous damping in spastic ankles was increased across the plantar flexion torque levels and at lower dorsi-flexion torques, reflecting increased passive viscous damping (P = 0.033). The more spastic plantar flexors showed higher viscous damping than dorsi-flexors at comparable torque levels (P < 0.047). Simultaneous characterizations of reflex and nonreflex changes in spastic hemiparesis may help to evaluate and treat them more effectively.

  16. Retrieval Interference in Syntactic Processing: The Case of Reflexive Binding in English

    OpenAIRE

    Patil, Umesh; Vasishth, Shravan; Lewis, Richard L.

    2016-01-01

    It has been proposed that in online sentence comprehension the dependency between a reflexive pronoun such as himself/herself and its antecedent is resolved using exclusively syntactic constraints. Under this strictly syntactic search account, Principle A of the binding theory—which requires that the antecedent c-command the reflexive within the same clause that the reflexive occurs in—constrains the parser's search for an antecedent. The parser thus ignores candidate antecedents that might m...

  17. Implementation of a smartphone as a wireless gyroscope application for the quantification of reflex response.

    Science.gov (United States)

    LeMoyne, Robert; Mastroianni, Timothy

    2014-01-01

    The patellar tendon reflex constitutes a fundamental aspect of the conventional neurological evaluation. Dysfunctional characteristics of the reflex response can augment the diagnostic acuity of a clinician for subsequent referral to more advanced medical resources. The capacity to quantify the reflex response while alleviating the growing strain on specialized medical resources is a topic of interest. The quantification of the tendon reflex response has been successfully demonstrated with considerable accuracy and consistency through using a potential energy impact pendulum attached to a reflex hammer for evoking the tendon reflex with a smartphone, such as an iPhone, application representing a wireless accelerometer platform to quantify reflex response. Another sensor integrated into the smartphone, such as an iPhone, is the gyroscope, which measures rate of angular rotation. A smartphone application enables wireless transmission through Internet connectivity of the gyroscope signal recording of the reflex response as an email attachment. The smartphone wireless gyroscope application demonstrates considerable accuracy and consistency for the quantification of the tendon reflex response.

  18. Females Exhibit Shorter Paraspinal Reflex Latencies than Males in Response to Sudden Trunk Flexion Perturbations

    Science.gov (United States)

    Miller, Emily M.; Slota, Gregory P.; Agnew, Michael J.; Madigan, Michael L.

    2010-01-01

    Background Females have a higher risk of experiencing low back pain or injury than males. One possible reason for this might be altered reflexes since longer paraspinal reflex latencies exist in injured patients versus healthy controls. Gender differences have been reported in paraspinal reflex latency, yet findings are inconsistent. The goal here was to investigate gender differences in paraspinal reflex latency, avoiding and accounting for potentially gender-confounding experimental factors. Methods Ten males and ten females underwent repeated trunk flexion perturbations. Paraspinal muscle activity and trunk kinematics were recorded to calculate reflex latency and maximum trunk flexion velocity. Two-way mixed model ANOVAs were used to determine the effects of gender on reflex latency and maximum trunk flexion velocity. Findings Reflex latency was 18.7% shorter in females than in males (P=0.02) when exposed to identical trunk perturbations, and did not vary by impulse (P=0.38). However, maximum trunk flexion velocity was 35.3% faster in females than males (P=0.01) when exposed to identical trunk perturbations, and increased with impulse (P<0.01). While controlling for differences in maximum trunk flexion velocity, reflex latency was 16.4% shorter in females than males (P=0.04). Implications The higher prevalence of low back pain and injury among females does not appear to result from slower paraspinal reflexes. PMID:20359800

  19. H-reflex modulation in the human medial and lateral gastrocnemii during standing and walking

    Science.gov (United States)

    Makihara, Yukiko; Segal, Richard L.; Wolpaw, Jonathan R.; Thompson, Aiko K.

    2011-01-01

    Introduction The soleus H-reflex is dynamically modulated during walking. However, modulation of the gastrocnemii H-reflexes has not been studied systematically. Methods The medial and lateral gastrocnemii (MG and LG) and soleus H-reflexes were measured during standing and walking in humans. Results Maximum H-reflex amplitude was significantly smaller in MG (mean 1.1 mV) or LG (1.1 mV) than in soleus (3.3 mV). Despite these size differences, the reflex amplitudes of the three muscles were positively correlated. The MG and LG H-reflexes were phase- and task-dependently modulated in ways similar to the soleus H-reflex. Discussion Although there are anatomical and physiological differences between the soleus and gastrocnemii muscles, the reflexes of the three muscles are similarly modulated during walking and between standing and walking. The findings support the hypothesis that these reflexes are synergistically modulated during walking to facilitate ongoing movement. PMID:22190317

  20. Establishing between-session reliability of TMS-conditioned soleus H-reflexes.

    Science.gov (United States)

    Gray, W A; Sabatier, M J; Kesar, T M; Borich, M R

    2017-02-15

    Transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) can be used to evaluate descending corticomotor influences on spinal reflex excitability through modulation of the Hoffman reflex (H-reflex). The purpose of this study was to characterize between-session reliability of cortical, spinal, and cortical-conditioned spinal excitability measures collected from the soleus muscle. Thirteen able-bodied young adult participants were tested over four sessions. Intraclass correlation coefficients were calculated to quantify between-session reliability of active motor threshold (AMT), unconditioned H-reflexes (expressed as a percentage of Mmax), and conditioned H-reflexes using short-latency facilitation (SLF) and long-latency facilitation (LLF). Pearson correlation coefficients were calculated to assess associations between H-reflex facilitation and unconditioned H-reflex amplitude. Between-session reliability for SLF (ICC=0.71) was higher than for LLF (ICC=0.45), was excellent for AMT (ICC=0.95), and was moderate for unconditioned H-reflexes (ICC=0.63). Our results suggest moderate-to-good reliability of SLF and LLF to evaluate cortical influences on spinal reflex excitability across multiple testing sessions in able-bodied individuals. Copyright © 2017 Elsevier B.V. All rights reserved.