WorldWideScience

Sample records for vestibulo-ocular reflex gain

  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. 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.

  3. 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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

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

    Science.gov (United States)

    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.

  11. 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.

  12. 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.

  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 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.

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

    Science.gov (United States)

    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.

  16. 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

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    Science.gov (United States)

    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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. 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

  3. 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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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 ...

  2. 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...

  3. 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

  4. 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...

  5. 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.

  6. 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.

  7. Soleus H-reflex gain in humans walking and running under simulated reduced gravity

    Science.gov (United States)

    Ferris, D. P.; Aagaard, P.; Simonsen, E. B.; Farley, C. T.; Dyhre-Poulsen, P.

    2001-01-01

    The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses.A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level.We recorded EMG from eight subjects walking (1.25 m s-1) and running (3.0 m s-1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by 30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9% Mmax) than running (-2.5% Mmax; P neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion.

  8. 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

  9. Context-specific adaptation of the gain of the oculomotor response to lateral translation using roll and pitch head tilts as contexts

    Science.gov (United States)

    Shelhamer, Mark; Peng, Grace C Y.; Ramat, Stefano; Patel, Vivek

    2002-01-01

    Previous studies established that vestibular and oculomotor behaviors can have two adapted states (e.g., gain) simultaneously, and that a context cue (e.g., vertical eye position) can switch between the two states. The present study examined this phenomenon of context-specific adaptation for the oculomotor response to interaural translation (which we term "linear vestibulo-ocular reflex" or LVOR even though it may have extravestibular components). Subjects sat upright on a linear sled and were translated at 0.7 Hz and 0.3 gpeak acceleration while a visual-vestibular mismatch paradigm was used to adaptively increase (x2) or decrease (x0) the gain of the LVOR. In each experimental session, gain increase was asked for in one context, and gain decrease in another context. Testing in darkness with steps and sines before and after adaptation, in each context, assessed the extent to which the context itself could recall the gain state that was imposed in that context during adaptation. Two different contexts were used: head pitch (26 degrees forward and backward) and head roll (26 degrees or 45 degrees, right and left). Head roll tilt worked well as a context cue: with the head rolled to the right the LVOR could be made to have a higher gain than with the head rolled to the left. Head pitch tilt was less effective as a context cue. This suggests that the more closely related a context cue is to the response being adapted, the more effective it is.

  10. 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.

  11. 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.......2 to 0.58 with an average of 0.14 (95 % CI 0.12-0.16) on the right ear and 0.17 (95 % CI 0.15-0.19) on the left ear. Occurrences of saccades in the same patient were reproduced in 93 % of the cases by all examiners. Kappa's coefficient on the occurrence of saccades was 0.83. Interclass correlation...

  12. VOR Gain Is Related to Compensatory Saccades in Healthy Older Adults

    Science.gov (United States)

    Anson, Eric R.; Bigelow, Robin T.; Carey, John P.; Xue, Qian-Li; Studenski, Stephanie; Schubert, Michael C.; Agrawal, Yuri

    2016-01-01

    Objective: Vestibulo-ocular reflex (VOR) gain is well-suited for identifying rotational vestibular dysfunction, but may miss partial progressive decline in age-related vestibular function. Since compensatory saccades might provide an alternative method for identifying subtle vestibular decline, we describe the relationship between VOR gain and compensatory saccades in healthy older adults. Methods: Horizontal VOR gain was measured in 243 subjects age 60 and older from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT). Saccades in each HIT were identified as either “compensatory” or “compensatory back-up,” i.e., same or opposite direction as the VOR response respectively. Saccades were also classified as “covert” (occurring during head movement) and “overt” (occurring after head movement). The relationship between VOR gain and percentage of HITs with saccades, as well as the relationship between VOR gain and saccade latency and amplitude, were evaluated using regression analyses adjusting for age, gender, and race. Results: In adjusted analyses, the percentage of HITs with compensatory saccades increased 4.5% for every 0.1 decrease in VOR gain (p saccade amplitude decreased 0.6° (p saccade amplitude increased 0.4° for every 0.1 increase in VOR gain. Conclusion: We observed significant relationships between VOR gain and compensatory saccades in healthy older adults. Lower VOR gain was associated with larger amplitude, shorter latency compensatory saccades. Compensatory saccades reflect underlying rotational vestibular hypofunction, and may be particularly useful at identifying partial vestibular deficits as occur in aging adults. PMID:27445793

  13. 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.

  14. Impaired H-Reflex Gain during Postural Loaded Locomotion in Individuals Post-Stroke.

    Directory of Open Access Journals (Sweden)

    Jing Nong Liang

    Full Text Available Successful execution of upright locomotion requires coordinated interaction between controllers for locomotion and posture. Our earlier research supported this model in the non-impaired and found impaired interaction in the post-stroke nervous system during locomotion. In this study, we sought to examine the role of the Ia afferent spinal loop, via the H-reflex response, under postural influence during a locomotor task. We tested the hypothesis that the ability to increase stretch reflex gain in response to postural loads during locomotion would be reduced post-stroke.Fifteen individuals with chronic post-stroke hemiparesis and 13 non-impaired controls pedaled on a motorized cycle ergometer with specialized backboard support system under (1 seated supported, and (2 non-seated postural-loaded conditions, generating matched pedal force outputs of two levels. H-reflexes were elicited at 90° crank angle.We observed increased H-reflex gain with postural influence in non-impaired individuals, but a lack of increase in individuals post-stroke. Furthermore, we observed decreased H-reflex gain at higher postural loads in the stroke-impaired group.These findings suggest an impaired Ia afferent pathway potentially underlies the defects in the interaction between postural and locomotor control post-stroke and may explain reduced ability of paretic limb support during locomotor weight-bearing in individuals post-stroke.These results support the judicious use of bodyweight support training when first helping individuals post-stroke to regain locomotor pattern generation and weight-bearing capability.

  15. Tuning of gravity-dependent and gravity-independent vertical angular VOR gain changes by frequency of adaptation.

    Science.gov (United States)

    Yakushin, Sergei B

    2012-06-01

    The gain of the vertical angular vestibulo-ocular reflex (aVOR) was adaptively increased and decreased in a side-down head orientation for 4 h in two cynomolgus monkeys. Adaptation was performed at 0.25, 1, 2, or 4 Hz. The gravity-dependent and -independent gain changes were determined over a range of head orientations from left-side-down to right-side-down at frequencies from 0.25 to 10 Hz, before and after adaptation. Gain changes vs. frequency data were fit with a Gaussian to determine the frequency at which the peak gain change occurred, as well as the tuning width. The frequency at which the peak gravity-dependent gain change occurred was approximately equal to the frequency of adaptation, and the width increased monotonically with increases in the frequency of adaptation. The gravity-independent component was tuned to the adaptive frequency of 0.25 Hz but was uniformly distributed over all frequencies when the adaptation frequency was 1-4 Hz. The amplitude of the gravity-independent gain changes was larger after the aVOR gain decrease than after the gain increase across all tested frequencies. For the aVOR gain decrease, the phase lagged about 4° for frequencies below the adaptation frequency and led for frequencies above the adaptation frequency. For gain increases, the phase relationship as a function of frequency was inverted. This study demonstrates that the previously described dependence of aVOR gain adaptation on frequency is a property of the gravity-dependent component of the aVOR only. The gravity-independent component of the aVOR had a substantial tuning curve only at an adaptation frequency of 0.25 Hz.

  16. Trigeminal high-frequency stimulation produces short- and long-term modification of reflex blink gain.

    Science.gov (United States)

    Ryan, Michael; Kaminer, Jaime; Enmore, Patricia; Evinger, Craig

    2014-02-01

    Reflex blinks provide a model system for investigating motor learning in normal and pathological states. We investigated whether high-frequency stimulation (HFS) of the supraorbital branch of the trigeminal nerve before the R2 blink component (HFS-B) decreases reflex blink gain in alert rats. As with humans (Mao JB, Evinger C. J Neurosci 21: RC151, 2001), HFS-B significantly reduced blink size in the first hour after treatment for rats. Repeated days of HFS-B treatment produced long-term depression of blink circuits. Blink gain decreased exponentially across days, indicating a long-term depression of blink circuits. Additionally, the HFS-B protocol became more effective at depressing blink amplitude across days of treatment. This depression was not habituation, because neither long- nor short-term blink changes occurred when HFS was presented after the R2. To investigate whether gain modifications produced by HFS-B involved cerebellar networks, we trained rats in a delay eyelid conditioning paradigm using HFS-B as the unconditioned stimulus and a tone as the conditioned stimulus. As HFS-B depresses blink circuits and delay conditioning enhances blink circuit activity, occlusion should occur if they share neural networks. Rats acquiring robust eyelid conditioning did not exhibit decreases in blink gain, whereas rats developing low levels of eyelid conditioning exhibited weak, short-term reductions in blink gain. These results suggested that delay eyelid conditioning and long-term HFS-B utilize some of the same cerebellar circuits. The ability of repeated HFS-B treatment to depress trigeminal blink circuit activity long term implied that it may be a useful protocol to reduce hyperexcitable blink circuits that underlie diseases like benign essential blepharospasm.

  17. 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.

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

    Science.gov (United States)

    Korsager, Leise Elisabeth Hviid; Schmidt, Jesper Hvass; Faber, Christian; Wanscher, Jens Højberg

    2016-12-01

    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. There is a lack of knowledge regarding the reliability of the two parameters. The objective was to investigate the reliability of vHIT by comparing gain values between examiners on the same subjects, and to see how differences affected the occurrence of saccades. 25 subjects who had undergone cochlear 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. VOR gain values and the occurrence of saccades in the diagram. Differences in gain values between examiners varied from 0.2 to 0.58 with an average of 0.14 (95 % CI 0.12-0.16) on the right ear and 0.17 (95 % CI 0.15-0.19) on the left ear. Occurrences of saccades in the same patient were reproduced in 93 % of the cases by all examiners. Kappa's coefficient on the occurrence of saccades was 0.83. Interclass correlation coefficient (ICC) of the gain values between examiners ranged from 0.62 to 0.70. Differences in gain values amongst examiners did not seem to affect the occurrence of saccades in the same patient. The occurrence of saccades, therefore, seems to be more reliable than the gain value in the evaluation of the vestibular function. Interpretation of vHIT results should, therefore, first depend on the occurrence of saccades and second on the gain value.

  19. Reduction in posterior semicircular canal gain by age in video head impulse testing. Observational study.

    Science.gov (United States)

    Guerra Jiménez, Gloria; Pérez Fernández, Nicolás

    2016-01-01

    and objectives: In-depth assessment of the vestibulo-ocular reflex with the new video systems available provides information on various previously-unidentified characteristics in patients with peripheral vestibular disorder. The aim of this work is to quantify how often pathological gain (uni- or bilateral) in the posterior semicircular canal (PSC) gain appears in video head-impulse testing (vHIT) with preservation of the gain in the rest of the semicircular canals, and to analyse the relation of this frequency with patient age and/or diagnosis. This was a prospective observational study on adults referred to our unit between June 2012 and February 2014. Age, sex, pathological antecedents, prior history of vestibular pathology, diagnosis and time of evolution of the clinical picture and its characteristics were recorded. Each patient underwent a complete otoneurological examination, including vHIT (Otometrics®). Depending on suspected diagnosis, patients also received cervical vestibular evoked myogenic potential (VEMP) testing, tonal audiometry and speech test, as well as assessment by Neurology and/or nuclear magnetic resonance or computed axial tomography scan imaging study. In all, 363 patients were assessed; 57 (16%) patients (33 males and 24 females; mean age, 57 ± 15 years) showed pathological PSC gains, 46 (81%) unilateral and 11 (19%) bilateral. Ménière's Disease was the most frequent diagnosis, followed by benign paroxysmal positional vertigo (27%). Patients with unilateral involvement were younger than those with bilateral (55 vs. 68 years; p=0.03). In the patients with bilateral involvement, PSC gain and age were related (-0.7; 0.04) and the gain value was symmetrical in both ears (0.7; p=0.05). The gain in the anterior and horizontal canals tended to decrease with age, but without statistical significance in our sample. Of the patients referred for an otoneurological consultation, 16% showed pathological PSC gain (unilateral in 81% and bilateral in

  20. Increase in H-reflex gain following 1 week of immobilization

    DEFF Research Database (Denmark)

    Jensen, Jesper Lundbye; Sørensen, Mie; Nielsen, Jens Bo

    . Abductor Pollicis Brevis (APB). Motor evoked potentials (MEPS) elicited by transcranial magnetic stimulation and H-reflexes were obtained at rest and during tonic contraction (10% of MVC) in both muscles. Maximal voluntary flexion torque decreased significantly following immobilization without any changes...... in the flexion torque elicited by supramaximal stimulation of the median nerve. Both at rest and during tonic contraction the H-reflex increased significantly following immobilization without significant changes in Mmax. MEP amplitudes did not change significantly following immobilization. One week after cast...

  1. The video head impulse test (vHIT of semicircular canal function – age dependent normative values of VOR gain in healthy subjects

    Directory of Open Access Journals (Sweden)

    Leigh Andrew McGarvie

    2015-07-01

    Full Text Available Background/Hypothesis. The video Head Impulse Test (vHIT is now widely used to test the function of each of the six semicircular canals individually by measuring the eye rotation response to an abrupt head rotation in the plane of the canal. The main measure of canal adequacy is the ratio of the eye movement response to the head movement stimulus i.e. the gain of the vestibulo-ocular reflex (VOR. However there is a need for normative data about how VOR gain is affected by age and also by head velocity, to allow the response of any particular patient to be compared to response of healthy subjects in their age range. In this study we determined for all six semicircular canals, normative values of VOR gain, for each canal across a range of head velocities, for healthy subjects in each decade of life.Study Design. The VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89. Methods. The compensatory eye movement response to a small, unpredictable, abrupt head rotation (head impulse was measured by the ICS Impulse prototype system. The same operator delivered every impulse to every subject. Results. VOR gain decreased at high head velocities, but was largely unaffected by age into the 80-89 year age group. There were some small but systematic differences between the two directions of head rotation, which appear to be largely due to the fact that in this study only the right eye was measured. The results are considered in relation to recent evidence about the effect of age on VOR performance.Conclusion. These normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss. VOR gain, as measured directly by the eye movement response to head rotation, seems largely unaffected by

  2. 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.

  3. Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

    Directory of Open Access Journals (Sweden)

    van der Helm Frans CT

    2009-07-01

    Full Text Available Abstract Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Methods Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Results Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects. Conclusion Post stroke, we found active posture tasking to be dominated by: 1 muscle weakness and 2 lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.

  4. 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 ...

  5. 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

  6. Muscle disuse caused by botulinum toxin injection leads to increased central gain of the stretch reflex in the rat

    DEFF Research Database (Denmark)

    Pingel, Jessica; Hultborn, Hans; Naslund-Koch, Lui

    2017-01-01

    . However, significant changes were also observed in post-activation depression of the MSR suggesting that plastic changes in transmission from Ia afferent to the motor neurons may also be involved. The data demonstrate that muscle paralysis induced by Btx injection is accompanied by plastic adaptations...... in the triceps surae muscle in rats. Experiments were performed in 21 rats. 8 rats were in a control group and 13 rats were injected with 6 IU of Btx in the left triceps surae muscle. Two weeks after Btx injection larger monosynaptic reflexes (MSR) were recorded from the left (injected) than the right (non...

  7. 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...

  8. 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...

  9. 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.

  10. 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.

  11. 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....

  12. 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....

  13. 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...

  14. 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.

  15. 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…

  16. 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.

  17. 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...

  18. 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....

  19. 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…

  20. The medial vestibular nuclei, a vulnerable target in thiamine deficiency.

    Science.gov (United States)

    Kattah, Jorge C; Guede, Cindy; Hassanzadeh, Bahareh

    2018-01-01

    Bilateral medial vestibular nuclei (MVN) is a common target in thiamine depletion and results in acute vestibular failure. Involvement of the MVN was present in 27 out of 38 brainstem sections reported in the largest thiamine deficiency autopsy cohort with Wernicke's encephalopathy. Serial clinical, imaging and vestibulo-ocular reflex gain measured with the video head impulse (vHIT) in one patient with acute thiamine deficiency. Low horizontal VOR gain correlated with an abnormal manual head impulse and with MRI evidence of MVN in an alcohol-dependent patient with low thiamine levels. The vertical VOR gain was either normal or mildly abnormal. Thiamine replacement and normal diet restored the VOR gain and MRI signal changes to normal. This single case study provides clinical-imaging correlation for symmetric MVN compromise in thiamine deficiency, its effect on the VOR gain and the favorable response to thiamine and diet replacement when identified early.

  1. 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…

  2. 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...

  3. 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.

  4. Visual-vestibular interaction in progressive supranuclear palsy.

    Science.gov (United States)

    Das, V E; Leigh, R J

    2000-01-01

    We measured the stability of gaze during horizontal head rotations at 1-3 Hz in four patients with progressive supranuclear palsy (PSP), while they viewed a stationary target. Median gain of compensatory eye movements was 0.94, similar to control subjects. During rotation in darkness, median gain of vestibulo-ocular reflex (VOR) was 0.88, similar to controls. Conversely, the median gain of smooth-pursuit eye movements at 1.0 Hz was 0.23, lower than controls. A simple superposition model of smooth pursuit and the VOR could not account for the observed gaze stability during fixation. Our results are further evidence that a visually mediated mechanism, independent of smooth pursuit, optimizes eye movements to compensate for head rotations.

  5. 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

  6. 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...

  7. 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...

  8. 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.

  9. 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

  10. 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).

  11. 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.

  12. 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

  13. Alexander's law during high-acceleration head rotations in humans.

    Science.gov (United States)

    Anagnostou, Evangelos; Heimberger, Joachim; Sklavos, Sokratis; Anastasopoulos, Dimitri

    2011-03-30

    Alexander's law states that the amplitude of the spontaneous nystagmus grows with increasing gaze in the direction of the fast phase. Using the search-coil method we employed head impulses at various eye-in-orbit azimuth angles to test (i) whether the normal vestibulo-ocular reflex (VOR) in the behaviorally relevant high-frequency range has intrinsic properties that could account for Alexander's law and (ii) whether such properties can also be shown in patients with unilateral vestibulopathy. We showed that the gain of the VOR remained unaffected by eye-in-orbit position in contols and in patients, both on ipsilesional and contralesional stimuli. These findings suggest that eye-in-orbit position does not directly modulate the activity in VOR pathways, neither during unbalanced but reciprocal (in controls), nor during unbalanced and nonreciprocal natural vestibular stimulation (in patients).

  14. Physical therapy for persons with vestibular disorders.

    Science.gov (United States)

    Whitney, Susan L; Alghwiri, Alia; Alghadir, Ahmad

    2015-02-01

    Persons with vestibular disorders experience symptoms of dizziness and balance dysfunction, resulting in falls, as well as impairments of daily life. Various interventions provided by physical therapists have been shown to decrease dizziness and improve postural control. In the present review, we will focus on the role of physical therapy in the management of vestibular symptoms in patients with peripheral and central vestibular disorders. Persons with both acute and chronic central and peripheral vestibular disorders improve with vestibular rehabilitation. New interventions during the past 5 years have been designed to enhance recovery from problems with balance and dizziness. Examples include the use of virtual reality, vibrotactile feedback, optokinetic flow, YouTube videos, and innovative methods to change the gain of the vestibulo-ocular reflex (VOR). Patients with central and peripheral vestibular disorders benefit from physical therapy interventions. Advances in physical therapy interventions include new methods to stimulate adaptation of the VOR and the vestibulospinal systems.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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...

  1. Three-dimensional head-mounted gaming task procedure maximizes effects of vestibular rehabilitation in unilateral vestibular hypofunction: a randomized controlled pilot trial.

    Science.gov (United States)

    Micarelli, Alessandro; Viziano, Andrea; Augimeri, Ivan; Micarelli, Domenico; Alessandrini, Marco

    2017-12-01

    Considering the emerging advantages related to virtual reality implementation in clinical rehabilitation, the aim of the present study was to discover possible (i) improvements achievable in unilateral vestibular hypofunction patients using a self-assessed head-mounted device (HMD)-based gaming procedure when combined with a classical vestibular rehabilitation protocol (HMD group) as compared with a group undergoing only vestibular rehabilitation and (ii) HMD procedure-related side effects. Therefore, 24 vestibular rehabilitation and 23-matched HMD unilateral vestibular hypofunction individuals simultaneously underwent a 4-week rehabilitation protocol. Both otoneurological measures (vestibulo-ocular reflex gain and postural arrangement by studying both posturography parameters and spectral values of body oscillation) and performance and self-report measures (Italian Dizziness Handicap Inventory; Activities-specific Balance Confidence scale; Zung Instrument for Anxiety Disorders, Dynamic Gait Index; and Simulator Sickness Questionnaire) were analyzed by means of a between-group/within-subject analysis of variance model. A significant post-treatment between-effect was found, and the HMD group demonstrated an overall improvement in vestibulo-ocular reflex gain on the lesional side, in posturography parameters, in low-frequency spectral domain, as well as in Italian Dizziness Handicap Inventory and Activities-specific Balance Confidence scale scores. Meanwhile, Simulator Sickness Questionnaire scores demonstrated a significant reduction in symptoms related to experimental home-based gaming tasks during the HMD procedure. Our findings revealed the possible advantages of HMD implementation in vestibular rehabilitation, suggesting it as an innovative, self-assessed, low-cost, and compliant tool useful in maximizing vestibular rehabilitation outcomes.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. Changes in soleus H-reflex during walking in middle-aged, healthy subjects

    DEFF Research Database (Denmark)

    Raffalt, Peter C; Alkjær, Tine; Simonsen, Erik B

    2015-01-01

    -reflex amplitude during walking was affected by aging, and changes during the swing phase could be seen in the middle-aged subjects. Subdividing the 2 age groups into groups of facilitated or suppressed swing-phase H-reflex revealed that the H-reflex amplitude modulation pattern in the group with facilitated swing......INTRODUCTION: To assess the effect of aging on stretch reflex modulation during walking, soleus H-reflexes obtained in 15 middle-aged (mean age 56.4±6.9 years) and 15 young (mean age 23.7±3.9 years) subjects were compared. METHODS: The H-reflex amplitude, muscle activity (EMG) of the soleus...... and tibialis anterior muscles, and EMG/H-reflex gain were measured during 4-km/h treadmill walking. RESULTS: The normalized H-reflex amplitude was lower in the swing phase for the middle-aged group, and there was no difference in muscle activity. EMG/H-reflex gain did not differ between groups. CONCLUSIONS: H...

  10. 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.

  11. 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

  12. 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

  13. [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.

  14. 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.

  15. 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...

  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. 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.

  18. 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.

  19. [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.

  20. 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

  1. 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.

  2. Educating the Reflexive Practitioner

    Directory of Open Access Journals (Sweden)

    Marc J. Neveu

    2012-09-01

    wearing any clothes.Notwithstanding such issues, I do believe the studio holds the potentialto be an empowering learning experience. The intention of this article is to question the mode of instruction in an architectural studio. I’ve structured the paper in three parts. First, I will briefly describe the findingsof the study made by the Carnegie Foundation for the Advancementof Teaching known as the Boyer Report.2 To develop and support the findings of the Boyer Report, I introduce the work of the educator Donald Schön. Though I see much merit in the Boyer Report, and Schön’sproposals, I argue that a more nuanced approach is required. I will recommend, therefore, in the second section of this paper that a meansof architectural education as based on the Socratic method may be amore productive approach. My reading of the Socratic method is basedprimarily on early Socratic dialogues and I will specifically use Charmidesto illustrate the issues that I believe are relevant to studio pedagogy.3 From my analysis of Charmides I will, in the third section of the essay,describe how the Socratic method is beneficial to studio pedagogy threeways: reflexive, non-propositional, and finally how Socrates’ approachmay indeed be practical. This last section will be illustrated with a studentproject. It is my conjecture that the Socratic method offers insight intocurrent discussions of educational theory, namely student-centered,project-based learning.

  3. 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...

  4. 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...

  5. 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...

  6. 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

  7. 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...

  8. 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.

  9. Soleus H-reflex phase-dependent modulation is preserved during stepping within a robotic exoskeleton.

    Science.gov (United States)

    Knikou, Maria; Hajela, Nupur; Mummidisetty, Chaithanya K; Xiao, Ming; Smith, Andrew C

    2011-07-01

    To investigate to what extent the phase-dependent modulation of the soleus H-reflex is preserved when bilateral leg movements are electromechanically driven by a robotic exoskeleton at different levels of body weight support (BWS) in healthy subjects. The soleus H-reflex was elicited by posterior tibial nerve stimulation with a 1-ms single pulse at an intensity that the M-waves ranged from 4% to 9% of the maximal M-wave across subjects. Stimuli were randomly dispersed across the step cycle which was divided into 16 equal bins. At each bin, a maximal M-wave was elicited 100 ms after the test H-reflex and was used to normalize the associated M-wave and H-reflex. Electromyographic (EMG) activity from major hip, knee, and ankle muscles was recorded with surface bipolar electrodes. For each subject and muscle, the integrated EMG profile was established and plotted as a function of the step cycle phases. The H-reflex gain was determined as the slope of the relationship between the H-reflex and soleus EMG amplitudes at 100 ms before the H-reflex for each bin. During robotic assisted stepping, the phase-dependent soleus H-reflex modulation pattern was preserved and was similar at 25% and 50% BWS, a linear relationship between soleus H-reflex amplitude and background activity was found, and the reflex gain did not change with alterations of the BWS level. EMG amplitudes were smaller at 50% compared to 25% BWS. Body unloading, decreased EMG amplitude of ankle extensors, and reduced ankle movement are not key factors for the soleus H-reflex phasic excitability to be manifested. Robotic devices are utilized for rehabilitation of gait in neurological disorders. Based on our findings, spinal interneuronal circuits involved in the phase-dependent modulation of the soleus H-reflex will be engaged in a physiological manner during robotic assisted stepping in neurological disorders. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland

  10. 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.

  11. 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....

  12. 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...

  13. 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....

  14. 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....

  15. 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

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

    Science.gov (United States)

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

    2010-09-01

    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. To investigate whether there is a supranuclear component to eye movement disorders in CPEO using eye movement recordings. 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 were measured using Eyelink II video-oculography. The asymptotic values of the peak velocity main sequence curves were reduced in the CPEO group compared to those of normal patients, with a mean of 161 degrees/s (95% CI 126 degrees/s to 197 degrees/s) compared with 453 degrees/s (95% CI 430 to 475 degrees/s), respectively. Saccadic latency was longer in CPEO (263 ms; 95% CI 250 to 278), compared to controls (185 ms; 95% CI 181 to 189). Smooth pursuit and VOR gains were impaired in CPEO, although this could be explained by non-supranuclear causes. VORS gain was identical in the two groups. This study does not support a supranuclear component to the ophthalmoplegia of CPEO, although the increased latencies observed may warrant further investigation.

  17. 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...

  18. 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)

  19. 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...

  20. 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...

  1. [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.

  2. 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.

  3. Compensatory Saccades Are Associated With Physical Performance in Older Adults: Data From the Baltimore Longitudinal Study of Aging.

    Science.gov (United States)

    Xie, Yanjun; Anson, Eric R; Simonsick, Eleanor M; Studenski, Stephanie A; Agrawal, Yuri

    2017-03-01

    To determine whether compensatory saccade metrics observed in the video head impulse test, specifically saccade amplitude and latency, predict physical performance. Cross-sectional analysis of the Baltimore Longitudinal Study of Aging, a prospective cohort study. National Institute on Aging Intramural Research Program Clinical Research Unit in Baltimore, Maryland. Community-dwelling older adults. Video head impulse testing was performed, and compensatory saccades and horizontal vestibulo-ocular reflex (VOR) gain were measured. Physical performance was assessed using the Short Physical Performance Battery (SPPB), which included the feet side-by-side, semitandem, tandem, and single-leg stance; repeated chair stands; and usual gait speed measurements. Compensatory saccade amplitude and latency, VOR gain, and SPPB performance. In 183 participants who underwent vestibular and SPPB testing (mean age 71.8 yr; 53% females), both higher mean saccade amplitude (odds ratio [OR] =1.62, p = 0.010) and shorter mean saccade latency (OR = 0.88, p = 0.004) were associated with a higher odds of failing the tandem stand task. In contrast, VOR gain was not associated with any physical performance measure. We observed in a cohort of healthy older adults that compensatory saccade amplitude and latency were associated with tandem stance performance. Compensatory saccade metrics may provide insights into capturing the impact of vestibular loss on physical function in older adults.

  4. Stretch reflex excitability of the anti-gravity ankle extensor muscle in elderly humans.

    Science.gov (United States)

    Kawashima, N; Nakazawa, K; Yamamoto, S-I; Nozaki, D; Akai, M; Yano, H

    2004-01-01

    To examine whether the stretch reflex excitability of the soleus muscle changes with age, stretch reflexes at rest (REST) and during weak voluntary contractions (ACT) were elicited in 18 older and 14 younger subjects. The amplitude of the stretch reflex responses and gain, defined as the gradient of the regression line for the relation between stretch reflex responses against the angular velocity of the applied perturbation, were evaluated in each short-latency (M1) and two long-latency components (M2 and M3). It was found that in the older group, both the amplitude and gain of the M1 component did not change from the REST to the ACT conditions, whereas in the younger group both variables significantly increased from the REST to ACT conditions. The latency of the M1 component was significantly shorter under the REST condition (older vs. younger: 51.8 +/- 7.37 vs. 55.1 +/- 8.69 ms), while no group differences were found in those variables under the ACT condition, suggesting that the muscle-tendon complexes of SOL muscles of the older subjects were less elastic and had less slack, probably due to age-related histochemical alterations. Further, the Hoffman reflex (H-reflex), elicited during the REST condition in 10 older and 11 younger subjects showed no significant differences, suggesting that the soleus motoneuron response to the Ia input was comparable between the two subject groups. The histochemical alterations occurring with the ageing process might augment the short-latency stretch reflex in the SOL muscle without enhancement of motoneuronal excitability, and this effect might be masked when the muscle is voluntarily activated.

  5. 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

  6. 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

  7. Frequency response of vestibular reflexes in neck, back, and lower limb muscles.

    Science.gov (United States)

    Forbes, Patrick A; Dakin, Christopher J; Vardy, Alistair N; Happee, Riender; Siegmund, Gunter P; Schouten, Alfred C; Blouin, Jean-Sébastien

    2013-10-01

    Vestibular pathways form short-latency disynaptic connections with neck motoneurons, whereas they form longer-latency disynaptic and polysynaptic connections with lower limb motoneurons. We quantified frequency responses of vestibular reflexes in neck, back, and lower limb muscles to explain between-muscle differences. Two hypotheses were evaluated: 1) that muscle-specific motor-unit properties influence the bandwidth of vestibular reflexes; and 2) that frequency responses of vestibular reflexes differ between neck, back, and lower limb muscles because of neural filtering. Subjects were exposed to electrical vestibular stimuli over bandwidths of 0-25 and 0-75 Hz while recording activity in sternocleidomastoid, splenius capitis, erector spinae, soleus, and medial gastrocnemius muscles. Coherence between stimulus and muscle activity revealed markedly larger vestibular reflex bandwidths in neck muscles (0-70 Hz) than back (0-15 Hz) or lower limb muscles (0-20 Hz). In addition, vestibular reflexes in back and lower limb muscles undergo low-pass filtering compared with neck-muscle responses, which span a broader dynamic range. These results suggest that the wider bandwidth of head-neck biomechanics requires a vestibular influence on neck-muscle activation across a larger dynamic range than lower limb muscles. A computational model of vestibular afferents and a motoneuron pool indicates that motor-unit properties are not primary contributors to the bandwidth filtering of vestibular reflexes in different muscles. Instead, our experimental findings suggest that pathway-dependent neural filtering, not captured in our model, contributes to these muscle-specific responses. Furthermore, gain-phase discontinuities in the neck-muscle vestibular reflexes provide evidence of destructive interaction between different reflex components, likely via indirect vestibular-motor pathways.

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

    perhaps to the firing patterns of the most recently recruited motoneurones.6. Under the conditions of these experiments, it appears that the stretch reflex has too small a gain to function as a very effective error-controlled position servo-mechanism.

  14. Effect of procaine infiltration into biceps brachii muscle in man on supraspinal control of reflex transmission.

    Science.gov (United States)

    Neilson, P D

    1973-02-01

    Sensitivity of the tonic stretch reflex (TSR) of biceps brachii in normal man was measured at different levels of voluntary contraction before and after gamma efferent nerve fibres were selectively blocked by infiltration of dilute procaine. The procaine infiltration reduced TSR sensitivity to one half of its control value. It had no effect, however, on the slope of the relation between TSR gain and level of voluntary contraction. It was concluded that the increase in TSR sensitivity associated with voluntary contraction was not mediated by the gamma efferent fibres and control of reflex transmission is therefore not the main function of the fusimotor system.

  15. Coordination of eye and head movements during smooth pursuit in patients with vestibular failure.

    Science.gov (United States)

    Waterston, J A; Barnes, G R; Grealy, M A; Luxon, L M

    1992-12-01

    During pursuit of smoothly moving targets with combined eye and head movements in normal subjects, accurate gaze control depends on successful interaction of the vestibular and head movement signals with the ocular pursuit mechanisms. To investigate compensation for loss of the vestibulo-ocular reflex during head-free pursuit in labyrinthine-deficient patients, pursuit performance was assessed and compared under head-fixed and head-free conditions in five patients with isolated bilateral loss of vestibular function. Target motion consisted of predictable and unpredictable pseudo-random waveforms containing the sum of three or four sinusoids. Comparison of slow-phase gaze velocity gains under head-free and head-fixed conditions revealed no significant differences during pursuit of any of the three pseudo-random waveforms. The finding of significant compensatory eye movement during active head movements in darkness in labyrinthine-deficient patients, which were comparable in character and gain to the vestibular eye movement elicited in normal subjects, probably explains the similarity of the head-fixed and head-free responses. In two additional patients with cerebellar degeneration and vestibular failure, no compensatory eye movement response was observed, implying that the cerebellum is necessary for the generation of such responses in labyrinthine-deficient patients.

  16. Oculomotor function during space flight and susceptibility to space motion sickness

    Science.gov (United States)

    Thornton, William E.; Uri, John J.

    Horizontal vestibulo-ocular reflex (VOR) and saccadic eye movements (SEM) were studied in 18 subjects before and during five Space Shuttle missions to evaluate the effects of weightlessness and correlations between results and susceptibility to and actual presence of space motion sickness (SMS). Active sinusoidal head oscillation was the stimulus for VOR tests with vision (VVOR), with eyes shaded (VOR-ES), and VOR suppression (VOR-S). Eye movements were recorded by electrooculography and head position by a potentiometer. No pathological nystagmus or other abnormal eye movements were seen. No significant in-flight changes were seen in the gain, phase shift or waveform of VVOR, VOR-ES or VOR-S. Statistically significant increases in saccadic latency and decreases in saccadic velocity were seen, with no change in saccadic accuracy. Preflight differences between SMS susceptible and non-susceptible subjects were noted only in VOR-S, with less complete suppression in susceptible subjects, a finding also seen in flight. During flight, VVOR gain was significantly increased in three non-affected subjects. Saccades of SMS-affected subjects showed increased latency and velocity and decreased accuracy compared to saccades of unaffected subjects.

  17. Strain differences in baroceptor reflex in adult Wistar Kyoto rats

    Directory of Open Access Journals (Sweden)

    Vitor E. Valenti

    2010-01-01

    Full Text Available OBJECTIVES: A subset of normotensive Sprague-Dawley rats show lower baroreflex sensitivity; however, no previous study investigated whether there are differences in baroreflex sensitivity within this subset. Our study compared baroreflex sensitivity among conscious rats of this specific subtype. METHODS: Male Wistar Kyoto (WKY rats (16 weeks old were studied. Cannulas were inserted into the abdominal aortic artery through the right femoral artery to measure mean arterial pressure (MAP and heart rate (HR. Baroreflex gain was calculated as the ratio between change in HR and MAP variation (ΔHR/ΔMAP in response to a depressor dose of sodium nitroprusside (SNP, 50 µg/kg, i.v. and a pressor dose of phenylephrine (PE, 8 µg/kg, i.v.. Rats were divided into four groups: 1 low bradycardic baroreflex (LB, baroreflex gain (BG between -1 and -2 bpm/mmHg tested with PE; 2 high bradycardic baroreflex (HB, BG < -2 bpm/mmHg tested with PE; 3 low tachycardic baroreflex (LT, BG between -1 and -2 bpm/mmHg tested with SNP and; 4 high tachycardic baroreflex (HT, BG < -2 bpm/mmHg tested with SNP. Significant differences were considered for p < 0.05. RESULTS: Approximately 37% of the rats showed a reduced bradycardic peak, bradycardic reflex and decreased bradycardic gain of baroreflex while roughly 23% had a decreased basal HR, tachycardic peak, tachycardic reflex and reduced sympathetic baroreflex gain. No significant alterations were noted with regard to basal MAP. CONCLUSION: There is variability regarding baroreflex sensitivity among WKY rats from the same laboratory.

  18. 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.

  19. 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.

  20. 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

  1. 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...

  2. 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

  3. 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.

  4. 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...

  5. The behaviour of the long-latency stretch reflex in patients with Parkinson's disease.

    Science.gov (United States)

    Rothwell, J C; Obeso, J A; Traub, M M; Marsden, C D

    1983-01-01

    The size of the long-latency stretch reflex was measured in a proximal (triceps) and distal (flexor pollicis longus) muscle in 47 patients with Parkinson's disease, and was compared with that seen in a group of 12 age-matched normal control subjects. The patients were classified clinically into four groups according to the degree of rigidity at the elbow or tremor. Stretch reflexes were evaluated while the subject was exerting a small force against a constant preload supplied by a torque motor, and the size of the reflex response was measured as fractional increase over basal levels of activity. When stretches were given at random intervals by increasing the force exerted by the motor by a factor of 2 or 3, there was a clear trend for the more severely affected patients to have larger long latency responses in the triceps muscle, although there was no change in the size of the short-latency, spinal component of the response. In contrast, there was no change in the size of the long-latency response of the flexor pollicis longus in any group of patients with Parkinson's disease. Despite any differences in reflex size, the inherent muscle stiffness of both muscles appeared to be normal in all groups of patients with Parkinson's disease, since the displacement trajectory of the limb following the force increase was the same as control values in the short (25 ms) period before reflex compensation could intervene. In 20 of the patients and in seven of the control subjects, servo-controlled, ramp positional disturbances were given to the thumb. Up to a velocity of 300°/s, the size of the long-latency stretch reflex was proportional to the log velocity of stretch. This technique revealed, in both moderately and severely rigid patients, increases in the reflex sensitivity of the flexor pollicis longus, which had not been clear using step torque stretches alone. However, whether using ramp or step displacements, long latency stretch reflex gain was not closely related to

  6. 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.

  7. 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.

  8. 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.

  9. 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…

  10. 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 ...

  11. Weight Gain during Pregnancy

    Science.gov (United States)

    ... Global Map Premature Birth Report Cards Careers Archives Pregnancy Before or between pregnancies Nutrition, weight & fitness Prenatal ... fitness > Weight gain during pregnancy Weight gain during pregnancy E-mail to a friend Please fill in ...

  12. Web site for GAIN

    OpenAIRE

    Brænden, Stig; Gjerde, Stian; Hansen, Terje, TAR

    2001-01-01

    The project started with an inquiry from GAIN, Graphic Arts Intelligence Network, on the September 26. 2000. GAIN currently has a website that is static, and is not functioning in a satisfying way. The desire is therefore to establish a new dynamic web site with the possibility for the GAIN members to update the page via a browser interface, and maintain their own profiles. In addition to this they would like a brand new and more functional design. GAIN also wants to e...

  13. 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

  14. The Glenn A. Fry award lecture 2013: blurred vision, spectacle correction, and falls in older adults.

    Science.gov (United States)

    Elliott, David B

    2014-06-01

    This article reviews the literature on how blurred vision contributes to falls, gait, and postural control and discusses how these are influenced by spectacle correction. Falls are common and represent a very serious health risk for older people. They are not random events as studies have shown that falls are linked to a range of intrinsic and extrinsic risk factors. Vision provides a significant input to postural control in addition to providing information about the size and position of hazards and obstacles in the travel pathway and allows us to safely negotiate steps and stairs. Many studies have shown that reduced vision is a significant risk factor for falls. However, randomized controlled trials of optometric interventions and cataract surgery have not shown the expected reduction in falls rate, which may be due to magnification changes (and thus vestibulo-ocular reflex gain) in those participants who have large changes in refractive correction. Epidemiological studies have also shown that progressive addition lens and bifocal wearers are twice as likely to fall as non-multifocal wearers, laboratory-based studies have shown safer adaptive gait with single-vision glasses than progressive addition lenses or bifocals, and a randomized controlled trial has shown that an additional pair of distance vision single-vision glasses for outdoor use can reduce falls rate. Clinical recommendations to help optometrists prevent their frail, older patients from falling are suggested.

  15. Wave Mechanics of the Vestibular Semicircular Canals.

    Science.gov (United States)

    Iversen, Marta M; Rabbitt, Richard D

    2017-09-05

    The semicircular canals are biomechanical sensors responsible for detecting and encoding angular motion of the head in 3D space. Canal afferent neurons provide essential inputs to neural circuits responsible for representation of self-position/orientation in space, and to compensatory circuits including the vestibulo-ocular and vestibulo-collic reflex arcs. In this work we derive, to our knowledge, a new 1D mathematical model quantifying canal biomechanics based on the morphology, dynamics of the inner ear fluids, and membranous labyrinth deformability. The model takes the form of a dispersive wave equation and predicts canal responses to angular motion, sound, and mechanical stimulation. Numerical simulations were carried out for the morphology of the human lateral canal using known physical properties of the endolymph and perilymph in three diverse conditions: surgical plugging, rotation, and mechanical indentation. The model reproduces frequency-dependent attenuation and phase shift in cases of canal plugging. During rotation, duct deformability extends the frequency bandwidth and enhances the high frequency gain. Mechanical indentation of the membranous duct at high frequencies evokes traveling waves that move away from the location of indentation and at low frequencies compels endolymph displacement along the canal. These results demonstrate the importance of the conformal perilymph-filled bony labyrinth to pressure changes and to high frequency sound and vibration. Published by Elsevier Inc.

  16. Semicircular canal plane head impulses detect absent function of individual semicircular canals.

    Science.gov (United States)

    Cremer, P D; Halmagyi, G M; Aw, S T; Curthoys, I S; McGarvie, L A; Todd, M J; Black, R A; Hannigan, I P

    1998-04-01

    We studied the human vestibulo-ocular reflex (VOR) in response to head 'impulses': brief, unpredictable, passive, high-acceleration (up to 4000 degrees/s2), low-amplitude (20-30 degrees) head rotations. We delivered the head impulses approximately in the plane of the semicircular canal (SCC) being tested. To test the anterior and posterior SCCs, the head impulses were delivered in a diagonal plane, midway between the frontal (roll) and sagittal (pitch) planes. We recorded head and eye position in three dimensions with scleral search coils in nine normal subjects, seven patients following unilateral surgical vestibular neurectomy and three patients following unilateral posterior SCC occlusion. In the post-surgical patients we demonstrated a severe, permanent VOR gain deficit (0.2-0.3) for head impulses directed toward any single non-functioning SCC. The sensitivity of the test depends on the physiological properties of primary vestibular afferents, and its specificity depends on the anatomical orientation of the SCCs. The diagonal head impulse is the first test of individual vertical SCC function in humans, and together with the horizontal head impulse, forms a comprehensive battery of SCC-plane tests. These canal-plane impulses could be useful in evaluating patients with vertigo or other vestibular disorders.

  17. 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.

  18. Vestibular Involvement in Patients With Otitis Media With Antineutrophil Cytoplasmic Antibody-associated Vasculitis.

    Science.gov (United States)

    Morita, Yuka; Takahashi, Kuniyuki; Izumi, Shuji; Kubota, Yamato; Ohshima, Shinsuke; Horii, Arata

    2017-01-01

    Otitis media (OM) with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (OMAAV) is a novel concept of ear disease that is characterized by progressive mixed or sensorineural hearing loss with occasional systemic involvement. Considering the accumulating knowledge about the characteristics of and treatment for auditory dysfunction in OMAAV, the objective of this study was to investigate the vestibular function and symptoms of patients with OMAAV. Retrospective chart review. University hospital. Thirty-one OMAAV patients met criteria proposed by the OMAAV study group in Japan. Clinical characteristics and vestibular tests. Eleven of 31 OMAAV patients had vestibular symptoms; 3 patients had acute vertigo attack with sudden hearing loss and 8 patients had chronic dizziness. Episodic vertigo was not seen in any of the patients. Three patients who received a less intensive therapy without immunosuppressive agents developed intractable persistent dizziness. All symptomatic patients and six of the nine OMAAV patients without vestibular symptoms showed unilateral or bilateral caloric weakness; therefore, vestibular involvement was present in 84% of OMAAV patients. Gain of vestibulo-ocular reflex was reduced in symptomatic patients. The eye-tracking test and optokinetic nystagmus revealed no evidence of central dysfunction. Vestibular dysfunction was seen in 84% of OMAAV patients. One-third of OMAAV patients showed vestibular symptoms such as acute vertigo attack or chronic dizziness, which are of peripheral origin. One-third of the symptomatic patients developed intractable dizziness. Initial intensive treatment by combination therapy with steroid and immunosuppressive agents may be essential for preventing the development of intractable dizziness.

  19. Balance disorders in childhood: Main etiologies according to age. Usefulness of the video head impulse test.

    Science.gov (United States)

    Sommerfleck, Patricia Alejandra; González Macchi, María Emilia; Weinschelbaum, Romina; De Bagge, Maximiliano Damián; Bernáldez, Patricia; Carmona, Sergio

    2016-08-01

    Balance disorders are common in adult patients but less usual in the pediatric population. When this symptomatology appears in children it is a cause for concern, both for parents and health-care professionals. To explain the balance disorders in children describing a case series and to discuss the main etiologies found according to age. A retrospective, observational, descriptive, and cross-sectional study was conducted. Patients aged 1-18 years who consulted because of balance disorders at the otolaryngology department of a pediatric tertiary-care hospital between March 2012 and July 2015. Two hundred and six patients were included in the study. Median age was 10 years. The most common diagnoses were vestibular migraine in 21.8% of the children, ataxia in 9.22%, benign paroxysmal vertigo of childhood in 7.77%, and post-traumatic vertigo in 6.31%.Overall, 61 videonystagmographies- of which 46 were normal - and 55 video head impulse tests - which were normal in 45 and showed abnormalities in the vestibulo-ocular reflex gain in 10 - were performed. In a child with balance disorders, the medical history and neurotological examination are essential. Vestibular migraine is the most commonly found disorder in every age group, and most of the patients have a family history of migraine. Ancillary studies, especially the video head-impulse test, provide important data to confirm the diagnosis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. 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.

  1. Correlation of climbing perception and eye movements during daytime and nighttime takeoffs using a flight simulator.

    Science.gov (United States)

    Tamura, Atsushi; Wada, Yoshiro; Shimizu, Naoki; Inui, Takuo; Shiotani, Akihiro

    2016-01-01

    This study suggests that the subjective climbing perception can be quantitatively evaluated using values calculated from induced eye movements, and the findings may aid in the detection of pilots who are susceptible to spatial disorientation in a screening test. The climbing perception experienced by a pilot during takeoff at night is stronger than that experienced during the day. To investigate this illusion, this study assessed eye movements and analyzed their correlation with subjective climbing perception during daytime and nighttime takeoffs. Eight male volunteers participated in this study. A simulated aircraft takeoff environment was created using a flight simulator and the maximum slow-phase velocities and vestibulo-ocular reflex gain of vertical eye movements were calculated during takeoff simulation. Four of the eight participants reported that their perception of climbing at night was stronger, while the other four reported that there was no difference between day and night. These perceptions were correlated with eye movements; participants with a small difference in the maximum slow-phase velocities of their downward eye movements between daytime and nighttime takeoffs indicated that their perception of climbing was the same under the two conditions.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. Gain weighted eigenspace assignment

    Science.gov (United States)

    Davidson, John B.; Andrisani, Dominick, II

    1994-01-01

    This report presents the development of the gain weighted eigenspace assignment methodology. This provides a designer with a systematic methodology for trading off eigenvector placement versus gain magnitudes, while still maintaining desired closed-loop eigenvalue locations. This is accomplished by forming a cost function composed of a scalar measure of error between desired and achievable eigenvectors and a scalar measure of gain magnitude, determining analytical expressions for the gradients, and solving for the optimal solution by numerical iteration. For this development the scalar measure of gain magnitude is chosen to be a weighted sum of the squares of all the individual elements of the feedback gain matrix. An example is presented to demonstrate the method. In this example, solutions yielding achievable eigenvectors close to the desired eigenvectors are obtained with significant reductions in gain magnitude compared to a solution obtained using a previously developed eigenspace (eigenstructure) assignment method.

  8. Some remarks on Romanian reflexive verbs derived by the prefix "în"

    Directory of Open Access Journals (Sweden)

    Veronica Tomescu

    2008-01-01

    Full Text Available The paper discusses a small group of Romanian reflexive verbs, denominals derived by means of the prefix în, as well as a group of transitive verbs which are reflexivized. Their behaviour will be briefly considered. A search on the Internet has also been made alongside the dictionary study in order to gain an insight into the frequency of use of certain forms.

  9. Vaccination against Weight Gain

    National Research Council Canada - National Science Library

    Eric P. Zorrilla; Shinichi Iwasaki; Jason A. Moss; Jason Chang; Jonathan Otsuji; Koki Inoue; Michael M. Meijler; Kim D. Janda

    2006-01-01

    .... Here we show that active vaccination of mature rats with ghrelin immunoconjugates decreases feed efficiency, relative adiposity, and body weight gain in relation to the immune response elicited...

  10. 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

  11. 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...

  12. 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.

  13. The tonic stretch reflex and spastic hypertonia after spinal cord injury.

    Science.gov (United States)

    Woolacott, Adam J; Burne, John A

    2006-09-01

    The operational definition of spasticity is focused on increased resistance of joints to passive rotation and the possible origin of this increased resistance in the induced tonic stretch reflex (TSR). This term is applied in the context of both cerebral and spinal injury, implying that a similar reflex mechanism underlies the two disorders. From recent studies it is clear that increased passive joint resistance in resting limbs following stroke is highly correlated with the induced TSR, but this evidence is lacking in spinal injury. The contribution of the TSR to hypertonia in spinal cord injury (SCI) is unclear and it is possible that hypertonia has a different origin in SCI. The contribution of resting and activated TSR activity to joint stiffness was compared in SCI and normal subjects. The magnitude of the TSR in ankle dorsiflexors (DF) and plantarflexors (PF) and mechanical ankle resistive torque were measured at rest and over a range of contraction levels in normal subjects. Similar measures were made in 13 subjects with SCI to the limits of their range of voluntary contraction. Normals and SCI received a pseudo-sinusoidal stretch perturbation of maximum amplitude +/- 20 degrees and frequency band 0.1-3.5 Hz that was comparable to that used in manual clinical testing of muscle tone. Elastic resistance and resonant frequency of the ankle joint, after normalization for limb volume, were significantly lower in complete and incomplete SCI than normal subjects. No reflex response related to stretch velocity was observed. Resting DF and PF TSR gain, when averaged over the tested band of frequencies, were significantly lower in complete SCI than in resting normal subjects (injury, Frankel score, number of spasms per day, Ashworth score or anti-spastic medication. DF and PF reflex gain were linearly related to voluntary contraction level and regression analysis produced similar slopes in incomplete SCI and normal subjects. Hence TSR loop gain was not significantly

  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. Digital automatic gain control

    Science.gov (United States)

    Uzdy, Z.

    1980-01-01

    Performance analysis, used to evaluated fitness of several circuits to digital automatic gain control (AGC), indicates that digital integrator employing coherent amplitude detector (CAD) is best device suited for application. Circuit reduces gain error to half that of conventional analog AGC while making it possible to automatically modify response of receiver to match incoming signal conditions.

  19. Visual-vestibular interaction during head-free pursuit of pseudorandom target motion in man.

    Science.gov (United States)

    Waterston, J A; Barnes, G R

    1992-01-01

    Recordings of head and eye movement were made during pursuit of mixed-frequency, pseudorandom target motion to study the mechanism of vestibulo-ocular reflex (VOR) suppression during head-free pursuit. When high velocity stimuli were used, slow-phase gaze velocity gains decreased significantly with increases in both absolute target velocity and the velocity ratio between the frequency components. These changes occurred independently of changes in the head displacement gain, which remained relatively constant at the lower frequency and were directly attributable to impaired suppression of the VOR. Similar effects were seen when visual feedback was degraded by tachistoscopic illumination of the target. The results indicate that visual feedback, rather than an efference copy of the head velocity signal, is essential for suppression of slow-phase vestibular eye movement during head-free pursuit. When head-free and head-fixed pursuit were compared, striking similarities were seen for both slow phase gaze velocity gain and phase, indicating that gaze control during smooth pursuit is largely independent of the degree of associated head movement. This suggests that the VOR is not switched off during head-free pursuit. An estimate of the underlying VOR gain was obtained by recording the vestibular response produced by active head movements in darkness. The rather higher estimates of VOR gain obtained using an imaginary earth-fixed target paradigm were found to predict head-free gains more closely than the gains obtained during imaginary pursuit of a moving target, suggesting that such measures may be more representative of the underlying VOR gain.

  20. Aging increases compensatory saccade amplitude in the video head impulse test

    Directory of Open Access Journals (Sweden)

    Eric R Anson

    2016-07-01

    Full Text Available Objective: Rotational vestibular function declines with age resulting in saccades as a compensatory mechanism to improve impaired gaze stability. Small reductions in rotational vestibulo-ocular reflex (VOR gain that would be considered clinically normal have been associated with compensatory saccades. We evaluated whether compensatory saccade characteristics varied as a function of age, independent of semicircular canal function as quantified by VOR gain.Methods: Horizontal VOR gain was measured in 243 participants age 27-93 from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT. Latency and amplitude of the first saccade (either covert – occurring during head impulse, or overt – occurring following head impulse were measured for head impulses with compensatory saccades (n = 2230 head impulses. The relationship between age and saccade latency, as well as the relationship between age and saccade amplitude, were evaluated using regression analyses adjusting for VOR gain, gender, and race.Results: Older adults (mean age 75.9 made significantly larger compensatory saccades relative to younger adults (mean age 45.0. In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory covert saccade (β = 0.015, p = 0.008. In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory overt saccade (β = 0.02, p < 0.001. Compensatory saccade latencies did not vary significantly by age. Conclusions: We observed that aging increases the compensatory catch-up saccade amplitude in healthy adults after controlling for VOR gain. Size of compensatory saccades may be useful in addition to VOR gain for characterizing vestibular function in aging adults.

  1. 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.

  2. 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...

  3. 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

  4. 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.

  5. Prevention of excess gain.

    Science.gov (United States)

    Stevens, J; Truesdale, K P; Wang, C-H; Cai, J

    2009-11-01

    Obesity prevention trials are designed to promote healthy weight. The success of these trials is often assessed using one of three metrics--means, incidence or prevalence. In this study, we point out conceptual shortcomings of these metrics and introduce an alternative that we call 'excess gain'. A mathematical demonstration using simulated data shows a scenario in which the statistical power of excess gain compares favorably with that of incidence and prevalence. Prevention of excess gain communicates an easily understood public health message that is applicable to all individuals regardless of weight status.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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…

  12. 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.

  13. 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...

  14. 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.

  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. 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

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. Usefulness of case reports to improve medical knowledge regarding trigemino-cardiac reflex in skull base surgery

    Directory of Open Access Journals (Sweden)

    Sadr-Eshkevari Pooan

    2011-04-01

    Full Text Available Abstract We describe the discovery of the trigemino-cardiac reflex by Schaller in 1999 and the continued improvement of the knowledge about the trigemino-cardiac reflex involved in neurosurgery, especially in skull base surgery, during the past several years. The achieved medical progress could be gained only by the practical experience described by different case reports and later case series that have been published in several principal scientific journals. Additionally, we explain the scientific as well as clinical importance of the communication of the case reports on TCR. Special reference has been given to the validity of the case reports for new phenomena in clinical medicine.

  2. Metamaterials with Gain

    Science.gov (United States)

    Hess, Ortwin

    2012-02-01

    Nanoplasmonic metamaterials are the key to an extreme control of light and allow us to conceive materials with negative or vanishing refractive index. Indeed, metamaterials enable a multitude of exciting and useful applications, such as subwavelength focusing, invisibility cloaking, and ``trapped rainbow'' stopping of light. The realization of these materials has recently advanced from the microwave to the optical regime. However, at optical wavelengths, metamaterials may suffer from high dissipative losses owing to the metallic nature of their constituent nanoplasmonic meta-molecules. It is therefore not surprising that overcoming loss restrictions by gain is currently one of the most important topics in metamaterials' research. At the same time, providing gain on the nanoplasmonic (metamolecular) level opens up exciting new possibilities such as a whole new type of metamaterial nano-laser with a cavity length of about a tenth of the wavelength. The talk gives an overview of the state of the art of gain-enhanced metamaterials. Particular focus will be placed on nano-plasmonic metamaterials (such as double-fishnet metamaterials) with integrated laser dyes as gain medium. The successful compensation of loss by gain is demonstrated on the meta-molecular level. On the basis of a comprehensive, microscopic Maxwell-Bloch Langevin approach of spatio-temporal light amplification and lasing in gain-enhanced nanoplasmonic (negative-index) metamaterials a methodology based on the discrete Poynting's theorem is introduced that allows dynamic tracing of the flow of electromagnetic energy into and out of ``microscopic'' channels (light field, plasmons, gain medium). It is shown that steady-state amplification can be achieved in nanoplasmonic metamaterials. Finally, a complex spatio-temporal interplay of light-field and coherent absorption dynamics is revealed in the lasing dynamics of a nanoplasmonic gain-enhanced double-fishnet metamaterial.

  3. 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.

  4. 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.

  5. 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.

  6. Can the Video Head Impulse Test Define Severity of Bilateral Vestibular Hypofunction?

    Science.gov (United States)

    Judge, Paul D; Janky, Kristen L; Barin, Kamran

    2017-06-01

    The objective of the study was to compare rotary chair and video head impulse test (vHIT) findings in patients with bilateral vestibular hypofunction (BVH) to determine whether vHIT can: 1) define severity of BVH and 2) accurately predict rotary chair findings in patients with BVH. Retrospective chart review. Research hospital. Twenty subjects with bilateral vestibular hypofunction as assessed by rotary chair. Rotary chair and vHIT. The main outcome measures were rotary chair phase, gain, and symmetry and vHIT vestibulo-ocular reflex (VOR) gain. Rotary chair and vHIT results were assessed and subjects were stratified into groups according to the severity of their vestibular hypofunction. For rotary chair, subjects were classified as mild, moderate, or severe BVH. For vHIT, subjects were classified as normal, unilateral, or bilateral. Average lateral canal vHIT VOR gain: 1) significantly increased as severity of BVH decreased, and 2) demonstrated a significant and positive, linear relationship with rotary chair gains. vHIT was in disagreement with rotary chair in the classification of five subjects, which could be due to right-left asymmetry of BVH. vHIT can serve as an initial tool for identifying patients with BVH. Lower vHIT gains are consistent with having severe BVH. There was disagreement between vHIT and rotary chair, though not for any patients with severe BVH. Compared with rotary chair, the clinical gold standard for identifying BVH, vHIT possesses 100% sensitivity for excluding severe BVH when average vHIT gains are greater than 0.46.

  7. A Mathematical Model to Investigate Gain-Induced Oscillation in the ...

    African Journals Online (AJOL)

    cce

    Since young adult humans tend to have quicker reflexes and better muscle tone than the elderly, they can be expected to have higher gain in .... Here PA, PV and R represent the pressure in the arteries and veins and resistance respectively, in either the systemic or pulmonary circulation. Thus there two such equations of ...

  8. 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.

  9. 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

  10. Receiver Gain Modulation Circuit

    Science.gov (United States)

    Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen

    2011-01-01

    A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by

  11. Relational Information Gain

    DEFF Research Database (Denmark)

    Lippi, Marco; Jaeger, Manfred; Frasconi, Paolo

    2011-01-01

    We introduce relational information gain, a refinement scoring function measuring the informativeness of newly introduced variables. The gain can be interpreted as a conditional entropy in a well-defined sense and can be efficiently approximately computed. In conjunction with simple greedy general......-to-specific search algorithms such as FOIL, it yields an efficient and competitive algorithm in terms of predictive accuracy and compactness of the learned theory. In conjunction with the decision tree learner TILDE, it offers a beneficial alternative to lookahead, achieving similar performance while significantly...

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Comparison of caloric and head-impulse tests during the attacks of Meniere's disease.

    Science.gov (United States)

    Lee, Sun-Uk; Kim, Hyo-Jung; Koo, Ja-Won; Kim, Ji-Soo

    2017-03-01

    To aid in diagnosis of Meniere's disease (MD) during the attacks using caloric and head-impulse tests (HITs). Retrospective case series review. We analyzed the results of bithermal caloric and HITs during the attacks in 16 patients with MD. Quantitative analyses of HITs were conducted using a magnetic search coil technique. In unilateral MD (14 patients, 42 semicircular canals), the head impulse gain of the vestibulo-ocular reflex (VOR) was either normal (28 of 42, 67%), decreased (8 of 42, 19%), or increased (6 of 42, 14%) for each semicircular canal in the affected ear. Likewise, the head impulse VOR gain was either normal (29 of 42, 69%), increased (11 of 42, 26%), or decreased (2 of 42, 5%) in the intact ear. The VOR gain for the horizontal canal was significantly lower on the affected side (P = 0.013). However, the VOR gains for the anterior and posterior canals did not differ between the sides (P = 0.270, P = 0.282). In bilateral MD (two patients, 12 semicircular canals), the VOR gain was either decreased (6 of 12, 50%) or normal (6 of 12, 50%) in either ear. In contrast, the caloric responses were usually decreased in the affected ear (7 of 11, 64%, including one with bilateral MD). During the attacks of MD, HITs showed varied results between the ears and among the canals, although the caloric responses were usually decreased in the involved ear. These dissociations suggest a frequency-dependent impairment of canal function or mechanical property of the endolymphatic hydrops during the attacks of MD. 4. Laryngoscope, 127:702-708, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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®

  5. Learn and gain

    CERN Document Server

    Al-Alami, Suhair Eyad Jamal

    2013-01-01

    Initiating the slogan ""love it, live it"", Learn and Gain includes eight short stories, chosen to illustrate various modes of narration, as well as to provoke reflection and discussion on a range of issues. All texts utilized here illustrate how great writers can, with their insight and gift for words, help us to see the world we live in, in new probing and exciting ways. What characterises the book, the author believes, is the integration of the skills of literary competence, communicative c...

  6. Gender gaps and gains.

    Science.gov (United States)

    Conly, S

    1998-01-01

    Findings from studies conducted worldwide indicate that educating girls allows them to gain more control over their lives, which, in turn, means that they have fewer, healthier children. In patriarchal societies, however, this education must last 6 or 7 years to be fully beneficial. Education of girls is also among the best economic investments a country can make because it leads to increased productivity and economic growth. However, women still suffer from a gender gap that has resulted in lower literacy among women and lower school attendance and duration of schooling among girls. However, gains have been made, and the gender gap in enrollment is narrowing in some regions, such as Latin America and East Asia. The gender gap continues its stranglehold, however, in the most populous and impoverished countries of sub-Saharan Africa. Enrollment rates in secondary schools have risen faster than for primary schools worldwide, with striking gains in East Asia. In some regions, such as Latin America, the secondary school enrollment rates are actually higher for girls than for boys. Strategies to improve girls' educational participation include 1) building more schools, 2) providing "girl-friendly" facilities, 3) increasing the number of women teachers, 4) improving the quality and relevance of the curriculum, 5) promoting education among parents, 6) providing sexual health education and services to reduce pregnancy-related drop-outs, and 7) making school hours flexible to accommodate girls' schedules.

  7. Comparison of Predictable Smooth Ocular and Combined Eye-Head Tracking Behaviour in Patients with Lesions Affecting the Brainstem and Cerebellum

    Science.gov (United States)

    Grant, Michael P.; Leigh, R. John; Seidman, Scott H.; Riley, David E.; Hanna, Joseph P.

    1992-01-01

    We compared the ability of eight normal subjects and 15 patients with brainstem or cerebellar disease to follow a moving visual stimulus smoothly with either the eyes alone or with combined eye-head tracking. The visual stimulus was either a laser spot (horizontal and vertical planes) or a large rotating disc (torsional plane), which moved at one sinusoidal frequency for each subject. The visually enhanced Vestibulo-Ocular Reflex (VOR) was also measured in each plane. In the horizontal and vertical planes, we found that if tracking gain (gaze velocity/target velocity) for smooth pursuit was close to 1, the gain of combined eye-hand tracking was similar. If the tracking gain during smooth pursuit was less than about 0.7, combined eye-head tracking was usually superior. Most patients, irrespective of diagnosis, showed combined eye-head tracking that was superior to smooth pursuit; only two patients showed the converse. In the torsional plane, in which optokinetic responses were weak, combined eye-head tracking was much superior, and this was the case in both subjects and patients. We found that a linear model, in which an internal ocular tracking signal cancelled the VOR, could account for our findings in most normal subjects in the horizontal and vertical planes, but not in the torsional plane. The model failed to account for tracking behaviour in most patients in any plane, and suggested that the brain may use additional mechanisms to reduce the internal gain of the VOR during combined eye-head tracking. Our results confirm that certain patients who show impairment of smooth-pursuit eye movements preserve their ability to smoothly track a moving target with combined eye-head tracking.

  8. A syntactic and lexical approach to French reflexive verbs

    Directory of Open Access Journals (Sweden)

    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.

  9. 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

  10. 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...

  11. 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.

  12. Age-Related Neurochemical Changes in the Vestibular Nuclei.

    Science.gov (United States)

    Smith, Paul F

    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 the vestibular nucleus complex (VNC), it is not entirely consistent. Whatever structural and functional changes occur in the VNC as a result of aging, either to cause vestibular impairment or to compensate for it, neurochemical changes must underlie them. However, the neurochemical changes that occur in the VNC with aging are poorly understood because the available literature is very limited. This review summarizes and critically evaluates the available evidence relating to the noradrenaline, serotonin, dopamine, glutamate, GABA, glycine, and nitric oxide neurotransmitter systems in the aging VNC. It is concluded that, at present, it is difficult, if not impossible, to relate the neurochemical changes observed to the function of specific VNC neurons and whether the observed changes are the cause of a functional deficit in the VNC or an effect of it. A better understanding of the neurochemical changes that occur during aging may be important for the development of potential drug treatments for age-related vestibular disorders. However, this will require the use of more sophisticated methodology such as in vivo microdialysis with single neuron recording and perhaps new technologies such as optogenetics.

  13. 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.

  14. 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...

  15. 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...

  16. 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…

  17. 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…

  18. Gaining Relational Competitive Advantages

    DEFF Research Database (Denmark)

    Hu, Yimei; Zhang, Si; Li, Jizhen

    2015-01-01

    Establishing strategic technological partnerships (STPs) with foreign partners is an increasingly studied topic within the innovation management literature. Partnering firms can jointly create sources of relational competitive advantage. Chinese firms often lack research and development (R......&D) capabilities but are increasingly becoming preferred technological partners for transnational corporations. We investigate an STP between a Scandinavian and a Chinese firm and try to explore how to gain relational competitive advantage by focusing on its two essential stages: relational rent generation...... and appropriation. Based on an explorative case study, we develop a conceptual framework that consists of process, organizational alliance factors, and coordination modes that we propose lead to relational competitive advantage....

  19. 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.

  20. Consumers' purchase of organic food products. A matter of convenience and reflexive practices.

    Science.gov (United States)

    Hjelmar, Ulf

    2011-04-01

    The aim of this study was to gain insight into the purchase of organic food products by consumers and to explore the main factors driving this process. This paper uses evidence from 16 in-depth interviews with consumers in Denmark carried out in 2008-2009. On the basis of the analysis two broad concepts are suggested: convenience behaviours and reflexive practices. Convenience behaviours are characteristic of pragmatic organic consumers. This type of shopping behaviour requires organic foods to be available in the local supermarket, they have to be clearly visible (preferably with an eco-label), and the price differential vis-à-vis conventional products have to be minimal. The analysis also showed that politically/ethically minded consumers have reflexive practices when purchasing organic food products: health considerations, ethical considerations (animal welfare), political considerations (environmentalism) and quality considerations (taste) play an important part for these consumers. Reflexive shopping practices can be sparked by life events (e.g. having children), "shocking" news about conventional food products and similar events, and news capable of creating a "cognitive dissonance" among consumers. The Danish case illustrates that the government needs to actively implement reforms and promote activities which make organic products a convenient choice for the pragmatic oriented consumer if their market share is to increase substantially. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Detection of isolated covert saccades with the video head impulse test in peripheral vestibular disorders.

    Science.gov (United States)

    Blödow, Alexander; Pannasch, Sebastian; Walther, Leif Erik

    2013-08-01

    The function of the semicircular canal receptors and the pathway of the vestibulo-ocular-reflex (VOR) can be diagnosed with the clinical head impulse test (cHIT). Recently, the video head impulse test (vHIT) has been introduced but so far there is little clinical experience with the vHIT in patients with peripheral vestibular disorders. The aim of the study was to investigate the horizontal VOR (hVOR) by means of vHIT in peripheral vestibular disorders. Using the vHIT, we examined the hVOR in a group of 117 patients and a control group of 20 healthy subjects. The group of patients included vestibular neuritis (VN) (n=52), vestibular schwannoma (VS) (n=31), Ménière's disease (MD) (n=22) and bilateral vestibulopathy (BV) (n=12). Normal hVOR gain was at 0.96 ± 0.08, while abnormal hVOR gain was at 0.44 ± 0.20 (79.1% of all cases). An abnormal vHIT was found in VN (94.2%), VS (61.3%), MD (54.5%) and BV (91.7%). Three conditions of refixation saccades occurred frequently in cases with abnormal hVOR: isolated covert saccades (13.7%), isolated overt saccades (34.3%) and the combination of overt and covert saccades (52.0%). The vHIT detects abnormal hVOR changes in the combination of gain assessment and refixation saccades. Since isolated covert saccades in hVOR changes can only be seen with vHIT, peripheral vestibular disorders are likely to be diagnosed incorrectly with the cHIT to a certain amount. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. Modulation of high-frequency vestibuloocular reflex during visual tracking in humans

    Science.gov (United States)

    Das, V. E.; Leigh, R. J.; Thomas, C. W.; Averbuch-Heller, L.; Zivotofsky, A. Z.; Discenna, A. O.; Dell'Osso, L. F.

    1995-01-01

    1. Humans may visually track a moving object either when they are stationary or in motion. To investigate visual-vestibular interaction during both conditions, we compared horizontal smooth pursuit (SP) and active combined eye-head tracking (CEHT) of a target moving sinusoidally at 0.4 Hz in four normal subjects while the subjects were either stationary or vibrated in yaw at 2.8 Hz. We also measured the visually enhanced vestibuloocular reflex (VVOR) during vibration in yaw at 2.8 Hz over a peak head velocity range of 5-40 degrees/s. 2. We found that the gain of the VVOR at 2.8 Hz increased in all four subjects as peak head velocity increased (P < 0.001), with minimal phase changes, such that mean retinal image slip was held below 5 degrees/s. However, no corresponding modulation in vestibuloocular reflex gain occurred with increasing peak head velocity during a control condition when subjects were rotated in darkness. 3. During both horizontal SP and CEHT, tracking gains were similar, and the mean slip speed of the target's image on the retina was held below 5.5 degrees/s whether subjects were stationary or being vibrated at 2.8 Hz. During both horizontal SP and CEHT of target motion at 0.4 Hz, while subjects were vibrated in yaw, VVOR gain for the 2.8-Hz head rotations was similar to or higher than that achieved during fixation of a stationary target. This is in contrast to the decrease of VVOR gain that is reported while stationary subjects perform CEHT.(ABSTRACT TRUNCATED AT 250 WORDS).

  9. 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.

  10. 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…

  11. (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

  12. 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

  13. 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,

  14. 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 ...

  15. 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

  16. 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 ...

  17. 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 ...

  18. 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

  19. 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.

  20. 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

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. Comparison of the bedside head impulse test with the video head impulse test in a clinical practice setting: a prospective study of 500 outpatients.

    Directory of Open Access Journals (Sweden)

    Chun Wai eYip

    2016-04-01

    Full Text Available Objectives: The primary aim was to determine the sensitivity, specificity, positive predictive value (PPV, and negative predictive value (NPV of the bedside head impulse test (bHIT using the video HIT (vHIT as the gold standard for quantifying the function of the vestibulo-ocular reflex (VOR. Secondary aims were to determine the bHIT inter-rater reliability, and sensitivity in detecting unilateral and bilateral vestibulopathy.Methods: In this prospective study, 500 consecutive outpatients presenting to a tertiary neuro-otology clinic with vertigo or dizziness of various vestibular etiologies who did not have any of the pre-defined exclusion criteria were recruited. Bedside HITs were done by three experienced neuro-otology clinicians masked to the diagnosis, and the results were compared with the vHIT. The patients were likewise blinded to the bHIT and vHIT findings. Patients with VOR deficits were identified on the vHIT by referencing to the pre-selected pathological gain of 40%, the bHIT sensitivity = 51.7% and 83%, respectively. For bilateral vestibulopathy, overall bHIT sensitivity = 66.3%, reaching 86.84% for severely reduced bidirectional gains.Conclusions: For the primary outcome, the bHIT had moderate sensitivity and low PPV. While the study did not elucidate the best choice for vHIT reference, it demonstrated how the bHIT test properties varied with vHIT thresholds: selecting a lower threshold improved the sensitivity but diminished the PPV, while a higher threshold had the opposite effect. The VOR was most likely normal if the bHIT was negative due to its high NPV. The bHIT was moderately sensitive for detecting unilateral and bilateral vestibulopathy overall, but better for certain subgroups.

  11. Synaptic plasticity in medial vestibular nucleus neurons: comparison with computational requirements of VOR adaptation.

    Directory of Open Access Journals (Sweden)

    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

  12. An Investigation of Horizontal Combined Eye-Head Tracking in Patients with Abnormal Vestibular and Smooth Pursuit Eye Movements

    Science.gov (United States)

    Huebner, William P.; Leigh, R. John; Seidman, Scott H.; Billian, Carl

    1993-01-01

    We investigated the interaction of smooth ocular pursuit (SP) and the vestibulo-ocular reflex (VOR) during horizontal, combined eye-head tracking (CEHT) in patients with abnormalities of either the VOR or SP movements. Our strategy was to apply transient stimuli that capitalized on the different latencies to onset of SP and the VOR. During CEHT of a target moving at 15 deg/sec, normal subjects and patients with VOR deficits all tracked the target with a gain close to 1.O. When the heads of normal subjects were suddenly and unexpectedly braked to a halt during CEHT, the eye promptly began to move in the orbit to track the target, but eye-in-orbit velocity transiently fell to about 60-70% of target velocity. In patients with deficient labyrinthine function, following the onset of the head brake, eye movements to track the target were absent, and SP movements were not generated until about 100 msec later. In patients with deficient SP, CEHT was superior to SP tracking with the head stationary; after the onset of the head brake, tracking eye movements were initiated promptly, but eye velocity was less than 50% of target velocity and increased only slightly thereafter. These results indicate that at least two mechanisms operate to overcome the VOR and allow gaze to track the target during CEHT: (1) the SP system provides a signal to cancel a normally-operating VOR (this cancellation signal is not needed by labyrinthine-deficient patients who have no VOR to cancel), and (2) a reduction of the gain of the VOR is achieved, an ability that is preserved even in patients with cerebral lesions that impair SP.

  13. Cerebellar motor learning: when is cortical plasticity not enough?

    Directory of Open Access Journals (Sweden)

    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.

  14. High-Speed Video-Oculography for Measuring Three-Dimensional Rotation Vectors of Eye Movements in Mice.

    Science.gov (United States)

    Imai, Takao; Takimoto, Yasumitsu; Takeda, Noriaki; Uno, Atsuhiko; Inohara, Hidenori; Shimada, Shoichi

    2016-01-01

    The mouse is the most commonly used animal model in biomedical research because of recent advances in molecular genetic techniques. Studies related to eye movement in mice are common in fields such as ophthalmology relating to vision, neuro-otology relating to the vestibulo-ocular reflex (VOR), neurology relating to the cerebellum's role in movement, and psychology relating to attention. Recording eye movements in mice, however, is technically difficult. We developed a new algorithm for analyzing the three-dimensional (3D) rotation vector of eye movement in mice using high-speed video-oculography (VOG). The algorithm made it possible to analyze the gain and phase of VOR using the eye's angular velocity around the axis of eye rotation. When mice were rotated at 0.5 Hz and 2.5 Hz around the earth's vertical axis with their heads in a 30° nose-down position, the vertical components of their left eye movements were in phase with the horizontal components. The VOR gain was 0.42 at 0.5 Hz and 0.74 at 2.5 Hz, and the phase lead of the eye movement against the turntable was 16.1° at 0.5 Hz and 4.88° at 2.5 Hz. To the best of our knowledge, this is the first report of this algorithm being used to calculate a 3D rotation vector of eye movement in mice using high-speed VOG. We developed a technique for analyzing the 3D rotation vector of eye movements in mice with a high-speed infrared CCD camera. We concluded that the technique is suitable for analyzing eye movements in mice. We also include a C++ source code that can calculate the 3D rotation vectors of the eye position from two-dimensional coordinates of the pupil and the iris freckle in the image to this article.

  15. Leading Gainful Employment Metric Reporting

    Science.gov (United States)

    Powers, Kristina; MacPherson, Derek

    2016-01-01

    This chapter will address the importance of intercampus involvement in reporting of gainful employment student-level data that will be used in the calculation of gainful employment metrics by the U.S. Department of Education. The authors will discuss why building relationships within the institution is critical for effective gainful employment…

  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: 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.

  19. 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.

  20. [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.

  1. 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

  2. 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.

  3. 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.

  4. 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,…

  5. 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...

  6. 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

  7. 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...

  8. 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...

  9. 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)....

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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)....

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. The interaction of visual, vestibular and extra-retinal mechanisms in the control of head and gaze during head-free pursuit.

    Science.gov (United States)

    Ackerley, Rochelle; Barnes, Graham R

    2011-04-01

    The ability to co-ordinate the eyes and head when tracking moving objects is important for survival. Tracking with eyes alone is controlled by both visually dependent and extra-retinal mechanisms, the latter sustaining eye movement during target extinction. We investigated how the extra-retinal component develops at the beginning of randomised responses during head-free pursuit and how it interacts with the vestibulo-ocular reflex (VOR). Subjects viewed horizontal step-ramp stimuli which occurred in pairs of identical velocity; velocity was randomised between pairs, ranging from ±5 to 40 deg s−1. In the first of each pair (short-ramp extinction) the target was visible for only 150 ms. In the second (initial extinction), after a randomised fixation period, the target was extinguished at motion onset, remaining invisible for 750 ms before reappearing for the last 200 ms of motion. Subjects used motion information acquired in the short-ramp extinction presentation to track the target from the start of unseen motion in the initial extinction presentation, using extra-retinal drive to generate smooth gaze and head movements scaled to target velocity. Gaze velocity rose more slowly than when visually driven, but had similar temporal development in head-free and head-fixed conditions. The difference in eye-in-head velocity between head-fixed and head-free conditions was closely related to head velocity throughout its trajectory, implying that extra-retinal drive was responsible for countermanding the VOR in the absence of vision. Thus, the VOR apparently remained active during head-free pursuit with near-unity gain. Evidence also emerged that head movements are not directly controlled by visual input, but by internal estimation mechanisms similar to those controlling gaze.

  3. Age-Related Neurochemical Changes in the Vestibular Nuclei

    Directory of Open Access Journals (Sweden)

    Paul eSmith

    2016-03-01

    Full Text Available There is evidence that the normal aging process is associated with impaired vestibulo-ocular (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 the vestibular nucleus complex (VNC, it is not entirely consistent. Whatever structural and functional changes occur in the VNC as a result of aging, either to cause vestibular impairment or to compensate for it, neurochemical changes must underlie them. However, the neurochemical changes that occur in the VNC with aging are poorly understood because the available literature is very limited. This review summarises and critically evaluates the available evidence relating to the noradrenaline, serotonin, dopamine, glutamate, GABA, glycine, and nitric oxide neurotransmitter systems in the aging VNC. It is concluded that, at present, it is difficult, if not impossible, to relate the neurochemical changes observed to the function of specific VNC neurons and whether the observed changes are the cause of a functional deficit in the VNC or an effect of it. A better understanding of the neurochemical changes that occur during aging may be important for the development of potential drug treatments for age-related vestibular disorders. However, this will require the use of more sophisticated methodology such as in vivo microdialysis with single neuron recording and perhaps new technologies such as optogenetics.

  4. 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.

  5. 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.

  6. The effects of isometric resistance training on stretch reflex induced tremor in the knee extensor muscles.

    Science.gov (United States)

    Durbaba, Rade; Cassidy, Angela; Budini, Francesco; Macaluso, Andrea

    2013-06-15

    This study examines the effect of 4 wk of high-intensity isometric resistance training on induced tremor in knee extensor muscles. Fourteen healthy volunteers were assigned to either the training group (n = 7) or the nontraining control group (n = 7). Induced tremor was assessed by measuring force fluctuations during anisometric contractions against spring loading, whose compliance was varied to allow for preferential activation of the short or long latency stretch reflex components. Effects of high-intensity isometric resistance training on induced tremor was assessed under two contraction conditions: relative force matching, where the relative level of activity was equal for both pre- and post-training sessions, set at 30% maximum voluntary contraction (MVC), and absolute force matching, where the level of activity was set to 30% pretrained MVC. The training group experienced a 26.5% increase in MVC in contrast to the 0.8% for the control group. For relative force-matching contractions, induced tremor amplitude and frequency did not change in either the training or control group. During absolute force-matching contractions, induced tremor amplitude was decreased by 37.5% and 31.6% for the short and long components, respectively, with no accompanying change in frequency, for the training group. No change in either measure was observed in the control group for absolute force-matching contractions. The results are consistent with high-intensity isometric resistance training induced neural changes leading to increased strength, coupled with realignment of stretch reflex automatic gain compensation to the new maximal force output. Also, previous reported reductions in anisometric tremor following strength training may partly be due to changed stretch reflex behavior.

  7. An artificial somatic-autonomic reflex pathway procedure for bladder control in children with spina bifida.

    Science.gov (United States)

    Xiao, Chuan-Guo; Du, Mao-Xin; Li, Bing; Liu, Zhao; Chen, Ming; Chen, Zhao-Hui; Cheng, Ping; Xue, Xiao-Nan; Shapiro, Ellen; Lepor, Herbert

    2005-06-01

    Neurogenic bladder is a major problem for children with spina bifida. Despite rigorous pharmacological and surgical treatment, incontinence, urinary tract infections and upper tract deterioration remain problematic. We have previously demonstrated the ability to establish surgically a skin-central nervous system-bladder reflex pathway in patients with spinal cord injury with restoration of bladder storage and emptying. We report our experience with this procedure in 20 children with spina bifida. All children with spina bifida and neurogenic bladder underwent limited laminectomy and a lumbar ventral root (VR) to S3 VR microanastomosis. The L5 dorsal root was left intact as the afferent branch of the somatic-autonomic reflex pathway after axonal regeneration. All patients underwent urodynamic evaluation before and after surgery. Preoperative urodynamic studies revealed 2 types of bladder dysfunction- areflexic bladder (14 patients) and hyperreflexic bladder with detrusor external sphincter dyssynergia (6). All children were incontinent. Of the 20 patients 17 gained satisfactory bladder control and continence within 8 to 12 months after VR microanastomosis. Of the 14 patients with areflexic bladder 12 (86%) showed improvement. In these cases bladder capacity increased from 117.28 to 208.71 ml, and mean maximum detrusor pressure increased from 18.35 to 32.57 cm H2O. Five of the 6 patients with hyperreflexic bladder demonstrated improvement, with resolution of incontinence. Urodynamic studies in these cases revealed a change from detrusor hyperreflexia with detrusor external sphincter dyssynergia and high detrusor pressure to nearly normal storage and synergic voiding. In these cases mean bladder capacity increased from 94.33 to 177.83 ml, and post-void residual urine decreased from 70.17 to 23.67 ml. Overall, 3 patients failed to exhibit any improvement. The artificial somatic-autonomic reflex arc procedure is an effective and safe treatment to restore bladder

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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)

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Diversity Gain through Antenna Blocking

    Directory of Open Access Journals (Sweden)

    V. Dehghanian

    2012-01-01

    Full Text Available As part of the typical usage mode, interaction between a handheld receiver antenna and the operator's RF absorbing body and nearby objects is known to generate variability in antenna radiation characteristics through blocking and pattern changes. It is counterintuitive that random variations in blocking can result in diversity gain of practical applicability. This diversity gain is quantified from a theoretical and experimental perspective. Measurements carried out at 1947.5 MHz verify the theoretical predictions, and a diversity gain of 3.1 dB was measured through antenna blocking and based on the utilized measurement setup. The diversity gain can be exploited to enhance signal detectability of handheld receivers based on a single antenna in indoor multipath environments.

  8. Heritability of gestational weight gain

    DEFF Research Database (Denmark)

    Andersson, Elina Scheers; Silventoinen, Karri; Tynelius, Per

    2015-01-01

    Gestational weight gain (GWG) is a complex trait involving intrauterine environmental, maternal environmental, and genetic factors. However, the extent to which these factors contribute to the total variation in GWG is unclear. We therefore examined the genetic and environmental influences...

  9. 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.

  10. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    Directory of Open Access Journals (Sweden)

    Yaoran Li

    Full Text Available Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4 were larger than gains in the capacity of the central executive (d = 1.6 that in turn were larger than gains in phonological memory span (d = 1.1. First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

  11. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    Science.gov (United States)

    Li, Yaoran; Geary, David C

    2013-01-01

    Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Operational gain : measuring the capture of genetic gain ...

    African Journals Online (AJOL)

    To test the operational gain concept, trials have been planted to eucalypts in the Kwa-Zulu Natal midlands. Two and a half year volume measurements from two of these trials are presented. The trials test a factorial combination of species, genetic level, stand density and level of silvicultural input. Results at two and a half ...

  18. 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.

  19. 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.

  20. 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...

  1. Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

    NARCIS (Netherlands)

    Meskers, C.G.M.; Schouten, A.C.; De Groot, J.H.; De Vlugt, E.; Van Hilten, B.J.J.; Van der Helm, F.C.T.; Arendzen, H.J.H.

    2009-01-01

    Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual

  2. Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

    NARCIS (Netherlands)

    Meskers, C.G.M.; Schouten, A.C.; De Groot, J.; De Vlugt, E.; Van Hilten, B.J.J.; Van der Helm, F.C.T.; Arendzen, H.J.H.

    2009-01-01

    Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to

  3. 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.

  4. 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, ...

  5. 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…

  6. 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.

  7. 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…

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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 ...

  15. 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.

  16. 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

  17. 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.

  18. 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,…

  19. 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…

  20. 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.

  1. 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.

  2. 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...

  3. 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

  4. 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 ...

  5. 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…

  6. 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...

  7. 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...

  8. 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

  9. 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.

  10. Kölliker-Fuse nuclei regulate respiratory rhythm variability via a gain-control mechanism.

    Science.gov (United States)

    Dhingra, Rishi R; Dutschmann, Mathias; Galán, Roberto F; Dick, Thomas E

    2017-02-01

    Respiration varies from breath to breath. On the millisecond timescale of spiking, neuronal circuits exhibit variability due to the stochastic properties of ion channels and synapses. Does this fast, microscopic source of variability contribute to the slower, macroscopic variability of the respiratory period? To address this question, we modeled a stochastic oscillator with forcing; then, we tested its predictions experimentally for the respiratory rhythm generated by the in situ perfused preparation during vagal nerve stimulation (VNS). Our simulations identified a relationship among the gain of the input, entrainment strength, and rhythm variability. Specifically, at high gain, the periodic input entrained the oscillator and reduced variability, whereas at low gain, the noise interacted with the input, causing events known as "phase slips", which increased variability on a slow timescale. Experimentally, the in situ preparation behaved like the low-gain model: VNS entrained respiration but exhibited phase slips that increased rhythm variability. Next, we used bilateral muscimol microinjections in discrete respiratory compartments to identify areas involved in VNS gain control. Suppression of activity in the nucleus tractus solitarii occluded both entrainment and amplification of rhythm variability by VNS, confirming that these effects were due to the activation of the Hering-Breuer reflex. Suppressing activity of the Kölliker-Fuse nuclei (KFn) enhanced entrainment and reduced rhythm variability during VNS, consistent with the predictions of the high-gain model. Together, the model and experiments suggest that the KFn regulates respiratory rhythm variability via a gain control mechanism. Copyright © 2017 the American Physiological Society.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Improved Gain Microstrip Patch Antenna

    Science.gov (United States)

    2015-08-06

    PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION...08-2015 Publication Improved Gain Microstrip Patch Antenna David A. Tonn Naval Under Warfare Center Division, Newport 1176 Howell St., Code 00L...Distribution A An antenna for mounting on a ground plane includes a dielectric substrate for mounting on the ground plane. A conductive patch

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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...

  6. 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.

  7. "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.

  8. 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.

  9. 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.

  10. GAIN Technology Workshops Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Braase, Lori Ann [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-08-01

    National and global demand for nuclear energy is increasing and United States (U.S.) global leadership is eroding. There is a sense of urgency with respect to the deployment of the innovative nuclear energy technologies. The Gateway for Accelerated Innovation in Nuclear (GAIN) initiative is based on the simultaneous achievement of three strategic goals. The first is maintaining global technology leadership within the U.S. Department of Energy (DOE). The second is enabling global industrial leadership for nuclear vendors and suppliers. The third is focused on utility optimization of nuclear energy within the clean energy portfolio. An effective public-private partnership is required to achieve these goals. DOEs recognizes the recent sense of urgency new developers and investors have in getting their concepts to market. They know that time to market for nuclear technology takes too long and the facilities needed to conduct the necessary research, development and demonstration (RD&D) activities are very expensive to develop and maintain. Early technologies, in the lower technology readiness levels (TRL) need materials testing, analysis, modeling, code development, etc., most of which currently exists in the DOE national laboratory system. However, mature technologies typically need large component testing and demonstration facilities, which are expensive and long-lead efforts. By understanding the needs of advanced nuclear technology developers, GAIN will connect DOE national laboratory capabilities (e.g., facilities, expertise, materials, and data) with industry RD&D needs. In addition, GAIN is working with the Nuclear Regulatory Commission (NRC) to streamline processes and increase understanding of the licensing requirements for advanced reactors.

  11. [Fast food promotes weight gain].

    Science.gov (United States)

    Stender, Steen; Dyerberg, Jørn; Astrup, Arne V

    2007-05-07

    The total amounts of fat in a fast food menu consisting of French fries and fried Chicken Nuggets from McDonald's and KFC, respectively, bought in 35 different countries vary from 41 to 71 gram. In most countries the menu contained unacceptably high amounts of industrially-produced trans fat which contributes to an increased risk of ischaemic heart disease, weight gain, abdominal fat accumulation and type 2 diabetes. The quality of the ingredients in fast food ought to be better and the size of the portions smaller and less energy-dense so that frequent fast food meals do not increase the risk of obesity and diseases among customers.

  12. 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

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  19. 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/...

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. A gain-coefficient switched Alexandrite laser

    NARCIS (Netherlands)

    Lee, C. J.; van der Slot, P. J. M.; Boller, K. J.

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ

  10. Estimating the potential gains from mergers

    DEFF Research Database (Denmark)

    Bogetoft, Peter; Wang, Dexiang

    2005-01-01

    We introduce simple production economic models to estimate the potential gains from mergers. We decompose the gains into technical ef¿ciency, size (scale) and harmony (mix) gains, and we discuss alternative ways to capture these gains. We propose to approximate the production processes using...

  11. Comparison of different exercise programs in the rehabilitation of patients with chronic peripheral vestibular dysfunction.

    Science.gov (United States)

    Szturm, T; Ireland, D J; Lessing-Turner, M

    1994-01-01

    The purpose of this study was to evaluate the effects of two exercise programs on balance performance in patients with chronic peripheral vestibular dysfunction and to assess whether these exercise programs induce adaptive modifications of the vestibulo-ocular reflex (VOR). Patients were randomly assigned to one of two groups. (1) Those in the Rehab (Reh) group (n = 11) received a comprehensive exercise program that consisted of balance retraining and goal-directed eye-head exercises under combinations of varied visual and somatosensory sensory conditions. Patients received 45-minute training sessions, three times per week for 12 weeks, and were instructed on a custom home exercise program. (2) Those in the Home group (n = 12) were instructed to perform the Cooksey-Cawthorne eye-head exercises at home, on a daily basis, for 12 weeks. In addition, after completion of the exercise program and a follow-up period, 7 of the participants in the Home group (here defined as the A group) chose to enter the Reh program (here defined as the B group). Balance performance was assessed by measuring the peak-to-peak magnitude and total amount of anterior-posterior body sway, and of horizontal (shear) ground reaction force during six test conditions, in which visual and somatosensory orientation cues were reduced or altered by rotation of the visual surround or support surface in proportion to the subject's sway, and in which vision was eliminated (eyes closed). The VOR response to step chair rotations of 60 degrees/s and 120 degrees/s, and the optokinetic reflex (OKN) response to 60 degrees/s constant velocity optokinetic stimuli were recorded. Left-right difference in VOR gain, VOR time constant, and OKN gain were determined. These tests were performed 1 day prior to start of treatment (TD 1), 6 weeks after start of treatment (TD 2), at the end of the 12-week treatment period (TD 3), and 5 months after end of treatment (TD 4). The findings revealed a significant improvement in

  12. Inter-rater reliability of categorical versus continuous scoring of fish vitality: Does it affect the utility of the reflex action mortality predictor (RAMP) approach?

    Science.gov (United States)

    Meeremans, Pieter; Yochum, Noëlle; Kochzius, Marc; Ampe, Bart; Tuyttens, Frank A M; Uhlmann, Sven Sebastian

    2017-01-01

    Scoring reflex responsiveness and injury of aquatic organisms has gained popularity as predictors of discard survival. Given this method relies upon the individual interpretation of scoring criteria, an evaluation of its robustness is done here to test whether protocol-instructed, multiple raters with diverse backgrounds (research scientist, technician, and student) are able to produce similar or the same reflex and injury score for one of the same flatfish (European plaice, Pleuronectes platessa) after experiencing commercial fishing stressors. Inter-rater reliability for three raters was assessed by using a 3-point categorical scale ('absent', 'weak', 'strong') and a tagged visual analogue continuous scale (tVAS, a 10 cm bar split in three labelled sections: 0 for 'absent', 'weak', 'moderate', and 'strong') for six reflex responses, and a 4-point scale for four injury types. Plaice (n = 304) were sampled from 17 research beam-trawl deployments during four trips. Fleiss kappa (categorical scores) and intra-class correlation coefficients (ICC, continuous scores) indicated variable inter-rater agreement by reflex type (ranging between 0.55 and 0.88, and 67% and 91% for Fleiss kappa and ICC, respectively), with least agreement among raters on extent of injury (Fleiss kappa between 0.08 and 0.27). Despite differences among raters, which did not significantly influence the relationship between impairment and predicted survival, combining categorical reflex and injury scores always produced a close relationship of such vitality indices and observed delayed mortality. The use of the continuous scale did not improve fit of these models compared with using the reflex impairment index based on categorical scores. Given these findings, we recommend using a 3-point categorical over a continuous scale. We also determined that training rather than experience of raters minimised inter-rater differences. Our results suggest that cost-efficient reflex impairment and injury scoring

  13. Inter-rater reliability of categorical versus continuous scoring of fish vitality: Does it affect the utility of the reflex action mortality predictor (RAMP approach?

    Directory of Open Access Journals (Sweden)

    Pieter Meeremans

    Full Text Available Scoring reflex responsiveness and injury of aquatic organisms has gained popularity as predictors of discard survival. Given this method relies upon the individual interpretation of scoring criteria, an evaluation of its robustness is done here to test whether protocol-instructed, multiple raters with diverse backgrounds (research scientist, technician, and student are able to produce similar or the same reflex and injury score for one of the same flatfish (European plaice, Pleuronectes platessa after experiencing commercial fishing stressors. Inter-rater reliability for three raters was assessed by using a 3-point categorical scale ('absent', 'weak', 'strong' and a tagged visual analogue continuous scale (tVAS, a 10 cm bar split in three labelled sections: 0 for 'absent', 'weak', 'moderate', and 'strong' for six reflex responses, and a 4-point scale for four injury types. Plaice (n = 304 were sampled from 17 research beam-trawl deployments during four trips. Fleiss kappa (categorical scores and intra-class correlation coefficients (ICC, continuous scores indicated variable inter-rater agreement by reflex type (ranging between 0.55 and 0.88, and 67% and 91% for Fleiss kappa and ICC, respectively, with least agreement among raters on extent of injury (Fleiss kappa between 0.08 and 0.27. Despite differences among raters, which did not significantly influence the relationship between impairment and predicted survival, combining categorical reflex and injury scores always produced a close relationship of such vitality indices and observed delayed mortality. The use of the continuous scale did not improve fit of these models compared with using the reflex impairment index based on categorical scores. Given these findings, we recommend using a 3-point categorical over a continuous scale. We also determined that training rather than experience of raters minimised inter-rater differences. Our results suggest that cost-efficient reflex impairment and

  14. Understanding weight gain at menopause.

    Science.gov (United States)

    Davis, S R; Castelo-Branco, C; Chedraui, P; Lumsden, M A; Nappi, R E; Shah, D; Villaseca, P

    2012-10-01

    The aim of this review was to summarize the literature regarding the impact of the menopause transition on body weight and body composition. We conducted a search of the literature using Medline (Ovid, 1946-present) and PubMed (1966-2012) for English-language studies that included the following search terms: 'menopause', 'midlife', 'hormone therapy' or 'estrogen' combined with 'obesity', 'body weight' or 'body composition'. Whereas weight gain per se cannot be attributed to the menopause transition, the change in the hormonal milieu at menopause is associated with an increase in total body fat and an increase in abdominal fat. Weight excess at midlife is not only associated with a heightened risk of cardiovascular and metabolic disease, but also impacts adversely on health-related quality of life and sexual function. Animal and human studies indicate that this tendency towards central abdominal fat accumulation is ameliorated by estrogen therapy. Studies mostly indicate a reduction in overall fat mass with estrogen and estrogen-progestin therapy, improved insulin sensitivity and a lower rate of development of type 2 diabetes. The hormonal changes across the perimenopause substantially contribute to increased abdominal obesity which leads to additional physical and psychological morbidity. There is strong evidence that estrogen therapy may partly prevent this menopause-related change in body composition and the associated metabolic sequelae. However, further studies are required to identify the women most likely to gain metabolic benefit from menopausal hormone therapy in order to develop evidence-based clinical recommendations.

  15. 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.

  16. The Video Head Impulse Test to Assess the Efficacy of Vestibular Implants in Humans

    Science.gov (United States)

    Guinand, Nils; Van de Berg, Raymond; Cavuscens, Samuel; Ranieri, Maurizio; Schneider, Erich; Lucieer, Floor; Kingma, Herman; Guyot, Jean-Philippe; Pérez Fornos, Angélica

    2017-01-01

    The purpose of this study was to evaluate whether it is possible to restore the high-frequency angular vestibulo-ocular reflex (aVOR) in patients suffering from a severe bilateral vestibulopathy (BV) and implanted with a vestibular implant prototype. Three patients (S1–3) participated in the study. They received a prototype vestibular implant with one to three electrode branches implanted in the proximity of the ampullary branches of the vestibular nerve. Five electrodes were available for electrical stimulation: one implanted in proximity of the left posterior ampullary nerve in S1, one in the left lateral and another one in the superior ampullary nerves in S2, and one in the right lateral and another one in the superior ampullary nerves in S3. The high-frequency aVOR was assessed using the video head impulse test (EyeSeeCam; EyeSeeTec, Munich, Germany), while motion-modulated electrical stimulation was delivered via one of the implanted vestibular electrodes at a time. aVOR gains were compared to control measurements obtained in the same patients when the device was not activated. In three out of the five tested electrodes the aVOR gain increased monotonically with increased stimulation strength when head impulses were delivered in the plane of the implanted canal. In these cases, gains ranging from 0.4 to values above 1 were measured. A “reversed” aVOR could also be generated when inversed stimulation paradigms were used. In most cases, the gain for excitatory head impulses was superior to that recorded for inhibitory head impulses, consistent with unilateral vestibular stimulation. Improvements of aVOR gain were generally accompanied by a concomitant decrease of corrective saccades, providing additional evidence of an effective aVOR. High inter-electrode and inter-subject variability were observed. These results, together with previous research, demonstrate that it is possible to restore the aVOR in a broad frequency range using motion

  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. 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.

  19. 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.

  20. Spatial organization of linear vestibuloocular reflexes of the rat: responses during horizontal and vertical linear acceleration.

    Science.gov (United States)

    Hess, B J; Dieringer, N

    1991-12-01

    1. The spatial properties of linear vestibuloocular reflexes (LVOR) were studied in pigmented rats in response to sinusoidal linear acceleration on a sled. The orientation of the animal on the sled was altered in 15 degrees steps over the range of 360 degrees. Horizontal, vertical, and torsional components of eye movements were recorded with the magnetic field search coil technique in complete darkness. Conjugacy of the two eyes was studied in the horizontal movement plane. 2. Acceleration along the optic axis of one eye (approximately 50 degrees lateral) induced maximal vertical responses in the ipsilateral eye and, at the same time, maximal torsional responses in the contralateral eye. These vertical and torsional responses of the LVOR coincide with those obtained when the respective coplanar vertical semicircular canals are stimulated. Such a congruence suggests a common reference frame for LVOR and angular vestibuloocular reflexes (AVOR), with the result that direct combination of signals indicating apparent and real head tilt is facilitated. 3. Transformations of vertical and torsional responses into head coordinates (pitch and roll) show that these movements are compensatory in direction for any combination of apparent head tilt in pitch and roll planes. 4. Gain (rotation of the eye/apparent rotation of the gravity direction) was approximately 0.3 at 0.1 Hz and decreased to approximately 0.1 at 1.0 Hz. Vertical responses tended to have a larger gain than torsional responses. Phase lag relative to peak acceleration increased from about -9 degrees to about -47 degrees over the same frequency range. 5. Vertical linear acceleration evoked only vertical eye movements at a frequency of 1.0 Hz. 6. Horizontal responses of both eyes were symmetric or asymmetric in amplitude and in-phase (conjugate) or out-of-phase (disconjugate) with respect to each other, depending on the direction of linear acceleration. Translation in the transverse direction evoked conjugate

  1. Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control During Variable Radius Centrifugation Following Space Flight

    Science.gov (United States)

    Wood, Scott J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

    2009-01-01

    Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, less than 20 cm radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. One result of this study will be to characterize the variability (gain, asymmetry) in both otolith-ocular responses and motion perception during variable radius centrifugation, and measure the time course of post-flight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Opioid-Induced Nausea Involves a Vestibular Problem Preventable by Head-Rest.

    Directory of Open Access Journals (Sweden)

    Nadine Lehnen

    Full Text Available Opioids are indispensable for pain treatment but may cause serious nausea and vomiting. The mechanism leading to these complications is not clear. We investigated whether an opioid effect on the vestibular system resulting in corrupt head motion sensation is causative and, consequently, whether head-rest prevents nausea.Thirty-six healthy men (26.6 ± 4.3 years received an opioid remifentanil infusion (45 min, 0.15 μg/kg/min. Outcome measures were the vestibulo-ocular reflex (VOR gain determined by video-head-impulse-testing, and nausea. The first experiment (n = 10 assessed outcome measures at rest and after a series of five 1-Hz forward and backward head-trunk movements during one-time remifentanil administration. The second experiment (n = 10 determined outcome measures on two days in a controlled crossover design: (1 without movement and (2 with a series of five 1-Hz forward and backward head-trunk bends 30 min after remifentanil start. Nausea was psychophysically quantified (scale from 0 to 10. The third controlled crossover experiment (n = 16 assessed nausea (1 without movement and (2 with head movement; isolated head movements consisting of the three axes of rotation (pitch, roll, yaw were imposed 20 times at a frequency of 1 Hz in a random, unpredictable order of each of the three axes. All movements were applied manually, passively with amplitudes of about ± 45 degrees.The VOR gain decreased during remifentanil administration (p<0.001, averaging 0.92 ± 0.05 (mean ± standard deviation before, 0.60 ± 0.12 with, and 0.91 ± 0.05 after infusion. The average half-life of VOR recovery was 5.3 ± 2.4 min. 32/36 subjects had no nausea at rest (nausea scale 0.00/0.00 median/interquartile range. Head-trunk and isolated head movement triggered nausea in 64% (p<0.01 with no difference between head-trunk and isolated head movements (nausea scale 4.00/7.25 and 1.00/4.5, respectively.Remifentanil reversibly decreases VOR gain at a half

  8. The Use of Modular, Electronic Neuron Simulators for Neural Circuit Construction Produces Learning Gains in an Undergraduate Anatomy and Physiology Course.

    Science.gov (United States)

    Petto, Andrew; Fredin, Zachary; Burdo, Joseph

    2017-01-01

    During the spring of 2016 at the University of Wisconsin-Milwaukee, we implemented a novel educational technology designed to teach undergraduates about the nervous system while allowing them to physically construct their own neural circuits. Modular, electronic neuron simulators called NeuroBytes were used by the students in BIOSCI202 Anatomy and Physiology I, a four-credit course consisting of three hours per week each of lecture and laboratory time. 162 students participated in the laboratory sessions that covered reflexes; 83 in the experimental sections used the NeuroBytes to build a model of the patellar tendon reflex, while 79 in the control sections participated in alternate reflex curricula. To address the question of whether or not the NeuroBytes-based patellar tendon reflex simulation brought about learning gains, the control and experimental group students underwent pre/post testing before and after their laboratory sections. We found that for several of the neuroscience and physiology concepts assessed on the test, the experimental group students had significantly greater declarative learning gains between the pre- and post-test as compared to the control group students. While there are numerous virtual neuroscience education tools available to undergraduate educators, there are relatively few designed to engage students in the basics of electrophysiology and neural circuitry using physical manipulatives, and none to our knowledge that allow them to build circuits from functioning hand-held "neurons."

  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. 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...

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. Can Beta Blockers Cause Weight Gain?

    Science.gov (United States)

    Beta blockers: Do they cause weight gain? Can beta blockers cause weight gain? Answers from Sheldon G. Sheps, ... can occur as a side effect of some beta blockers, especially the older ones, such as atenolol (Tenormin) ...

  1. Simulating Muscle-Reflex Dynamics in a Simple Hopping Robot

    Science.gov (United States)

    Seyfarth, Andre; Kalveram, Karl Theodor; Geyer, Hartmut

    In legged systems, springy legs facilitate gaits with subsequent contact and flight phases. Here, we test whether electrical motors can generate leg behaviors suitable for stable hopping. We built a vertically operating sledge actuated by a motor-driven leg. The motor torque simulates either a linear leg spring or a muscle-reflex system. For stable hopping significant energy supply was required after midstance. This was achieved by enhancing leg stiffness or by continuously applying positive force feedback to the simulated muscle. The muscle properties combined with positive force feedback result in spring-like behavior which enables stable hopping with adjustable hopping height.

  2. Health technology assessment: a sociological commentary on reflexive innovation.

    Science.gov (United States)

    Webster, Andrew

    2004-01-01

    This study provides a sociological commentary on the current debates within health technology assessment (HTA), specifically in response to the approaches taken in France, The Netherlands, Sweden, and the United Kingdom. It argues that HTA is part of a wider reflexive innovation system that seeks to order current and prospective technologies. The study discusses the socio-political process of HTA priority setting, the rhetorical role of HTA, the localised and contingent use of HTA, and the policy gap between guidelines and practice. It argues for the development of new types of methodologies for assessment and for a stronger social embedding of HTA practice.

  3. Semiotic scaffolding of the social self in reflexivity and friendship

    DEFF Research Database (Denmark)

    Emmeche, Claus

    2015-01-01

    The individual and social formation of a human self, from its emergence in early childhood through adolescence to adult life, has been described within philosophy, psychology and sociology as a product of developmental and social processes mediating a linguistic and social world. Semiotic...... scaffolding is a multi-level phenomenon. Focusing upon levels of semiosis specific to humans, the formation of the personal self and the role of friendship and similar interpersonal relations in this process is explored through Aristotle’s classical idea of the friend as ‘another self’, and sociologist...... of the emerging self, such processes are heterogeneous and contingent upon different modes of reflexivity....

  4. The Flynn effect in Korea: Large gains

    NARCIS (Netherlands)

    te Nijenhuis, J.; Cho, S.H.; Murphy, R.; Lee, K.H.

    2012-01-01

    Secular gains in IQ test scores have been reported for many Western countries. This is the first study of secular IQ gains in South Korea, using various datasets. The first question is what the size of the Flynn effect in South Korea is. The gains per decade are 7.7 points for persons born between

  5. Maternal Weight Gain Biosocial Characteristics And Perinatal ...

    African Journals Online (AJOL)

    Two perinatal deaths occurred, with a perinatal mortality rate of 9.52/ 1000.Their mother's weight gains were not attributable to the deaths. Conclusion The study has shown that parity and social class significantly affect maternal weight gain in pregnancy. Even though the mean weight gain in this study was 8.58 ± 3.61kg, ...

  6. (Zingiberaceae Aframomum melegueta ) on gestational weight gain

    African Journals Online (AJOL)

    Increased gestational weight gain is associated with higher rates of complications of pregnancy and delivery. Gestational weight gain of 9-12 Kg has been associated with the best outcome for both mothers and infants. However, weight gain in most pregnant women is not within this range, perhaps due to the difficulty of ...

  7. Muscle stiffness and spinal stretch reflex sensitivity in the triceps surae.

    Science.gov (United States)

    Blackburn, J Troy; Padua, Darin A; Guskiewicz, Kevin M

    2008-01-01

    Greater musculotendinous stiffness may enhance spinal stretch reflex sensitivity by improving mechanical coupling of the muscle spindle and the stretch stimulus. This heightened sensitivity would correspond with a shorter latency and higher-amplitude reflex response, potentially enhancing joint stability. To compare spinal stretch reflex latency and amplitude across groups that differed in musculotendinous stiffness. Static group comparisons. Research laboratory. Forty physically active individuals (20 men, 20 women). We verified a sex difference in musculotendinous stiffness and compared spinal stretch reflex latency and amplitude in high-stiffness (men) and low-stiffness (women) groups. We also evaluated relationships between musculotendinous stiffness and spinal stretch reflex latency and amplitude, respectively. Triceps surae musculotendinous stiffness and soleus spinal stretch reflex latency and amplitude were assessed at 30% of a maximal voluntary isometric plantar-flexion contraction. The high-stiffness group demonstrated significantly greater stiffness (137.41 +/- 26.99 N/cm) than the low-stiffness group did (91.06 +/- 20.10 N/cm). However, reflex latency (high stiffness = 50.11 +/- 2.07 milliseconds, low stiffness = 48.26 +/- 2.40 milliseconds) and amplitude (high stiffness = 0.28% +/- 0.12% maximum motor response, low stiffness = 0.31% +/- 0.16% maximum motor response) did not differ significantly across stiffness groups. Neither reflex latency (r = .053, P = .746) nor amplitude (r = .073, P = .653) was related significantly to musculotendinous stiffness. A moderate level of pretension (eg, 30%) likely eliminates series elastic slack; thus, a greater change in force per unit-of-length change (ie, heightened stiffness) would have minimal effects on coupling of the muscle spindle and the stretch stimulus and, therefore, on spinal stretch reflex sensitivity. It appears unlikely that differences in musculotendinous stiffness influenced spinal stretch reflex

  8. Preferential Impairment of the Contralesional Posterior Semicircular Canal in Internuclear Ophthalmoplegia

    Directory of Open Access Journals (Sweden)

    Seung-Han Lee

    2017-09-01

    Full Text Available BackgroundThe vertical vestibulo-ocular reflex (VOR may be impaired in internuclear ophthalmoplegia (INO as the medial longitudinal fasciculus (MLF conveys VOR-signals from the vertical semicircular canals. It has been proposed that signals from the contralesional posterior semicircular canal (PSC are exclusively transmitted through the MLF, while for the contralesional anterior canal other pathways exist.ObjectiveHere, we aimed to characterize dysfunction in individual canals in INO-patients using the video-head-impulse test (vHIT and to test the hypothesis of dissociated vertical canal impairment in INO.MethodsVideo-head-impulse testing and magnetic resonance imaging were obtained in 21 consecutive patients with unilateral (n = 16 or bilateral (n = 5 INO and 42 controls. VOR-gains and compensatory catch-up saccades were analyzed and the overall function (normal vs. impaired of each semicircular canal was rated.ResultsIn unilateral INO, largest VOR-gain reductions were noted in the contralesional PSC (0.55 ± 0.11 vs. 0.89 ± 0.08, p < 0.001, while in bilateral INO both posterior (0.43 ± 0.11 vs. 0.89 ± 0.08, p < 0.001 and anterior (0.58 ± 0.19 vs. 0.88 ± 0.09, p < 0.001 canals showed marked drops. Small, but significant VOR-gain reductions were also found in the other canals in unilateral and bilateral INO-patients. Impairment of overall canal function was restricted to the contralesional posterior canal in 60% of unilateral INO-patients, while isolated involvement of the posterior canal was rare in bilateral INO-patients (20%. Reviewers correctly identified the INO-pattern in 15/21 (71% patients and in all controls (sensitivity = 84.2% [95%-CI = 0.59.5–95.8]; specificity = 95.5% [95%-CI = 83.3–99.2].ConclusionUsing a vHIT based overall rating of canal function, the correct INO-pattern could be identified with high accuracy. The predominant and often selective impairment of

  9. Cough reflex sensitivity in adolescents with diabetic autonomic neuropathy

    Directory of Open Access Journals (Sweden)

    Ciljakova M

    2009-12-01

    Full Text Available Abstract Objective Diabetic autonomic neuropathy (DAN is one of the chronic complications of diabetes mellitus which can involve one or more organ systems. DAN without apparent symptoms is more often in childhood and adolescence. While heart rate variability (HRV and Ewing's battery of cardiovascular tests are regarded as a gold standard for the diagnosis of DAN, the examination of cough reflex sensitivity (CRS is another possibility. The aim of this study was to compare HRV and CRS in children with diabetes mellitus. Materials and methods Sixty one patients (37 girls, 24 boys aged 15-19 suffering from diabetes mellitus type 1 completed the study. Based on HRV, patients were divided into 2 groups - with DAN (n = 25 and without DAN (n = 32, 4 patients were excluded because of ambiguous results. CRS was studied in each patient by inhalation of gradually increasing concentration of capsaicin. Results Subjects with DAN required a significantly higher concentration of capsaicin needed to evoke 2 coughs (median 625 μmol/l, IQR 68.4-625.0 μmol/l vs. median 29.3 μmol/l, IQR 9.8-156.3 μmol/l, P Conclusion Diabetes mellitus lowers the cough response. Cough reflex sensitivity appears to be another sensitive method for the evaluation of DAN in diabetes.

  10. The palmo-mental reflex in vibroacoustic disease.

    Science.gov (United States)

    Martinho Pimenta, A J; Castelo Branco, M S; Castelo Branco, N A

    1999-03-01

    Vibroacoustic disease (VAD), is a multisystemic nosological entity, caused by occupational exposure to large pressure amplitude (> or = 90 dB SPL) and low frequency (< or = 500 Hz) (LPALF) noise. The most common neurological finding in patients with VAD is the palmomental reflex (PMR). The aim of this study is to evaluate the frequency and characteristics of this primitive reflex in a population of VAD patients. Sixty individuals, occupationally exposed to LPALF noise underwent a neurological examination. In each one, unilateral contraction of the chin muscles was triggered through the stimulation of the thenar eminence. When a response habituation was observed, or when there was no response except previously existing skin retraction and small dimples, an EMG was performed. All these subjects also received brain MRI and measurement of endogenous evoked potentials. Thirty individuals presented unilateral or bilateral PMR; 26 of these presented changes in the brain MRI. EMG measurement evidenced continuous contraction of the chin muscles, without visible PMR, triggered by the stimulation of the thenar eminence. PMR is present in 50% of the patients with VAD. In the VAD patients, the frequency of abnormal chin muscle activity is higher than the frequency of PMR and represents a loss of the cortical control over the brainstem structures.

  11. Enhanced blink reflex recovery in juvenile myoclonic epilepsy.

    Science.gov (United States)

    Kandemir, Melek; Gündüz, Ayşegül; Uzun, Nurten; Yeni, S Naz; Kızıltan, Meral E

    2015-11-16

    Juvenile myoclonic epilepsy (JME), which has been attributed to the dysfunction of cortico-thalamic pathway, has been considered to be one of the system epilepsies. However, electrophysiological and functional neuroimaging techniques have revealed the functional involvement of various parts of the central nervous system, also. Here, we aimed to analyze the role of brainstem circuits in JME by using the blink reflex recovery cycle (BRrc). Electrophysiological recordings of 18 JME patients together with age and gender matched 18 healthy subjects were made during single and paired supraorbital stimulation. Constant current paired stimuli were delivered at interstimulus intervals (ISI) of 200 and 400ms. Amplitudes of R2 responses were measured on the non-dominant side, and percentages of the recovery cycles were calculated. All participants had normal and similar R1 and R2 components of blink reflex (BR). At ISI of 400ms, R2 recoveries were significantly higher in the JME group compared to healthy subjects (p=0.040). There was no correlation between R2-BRrc and ages of JME patients, disease duration and daily dosage of valproic acid. We suggest that in JME, the integrity of BR circuit is preserved while the excitability of the brainstem BR circuitry is enhanced. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Hypothalamic stimulation and baroceptor reflex interaction on renal nerve activity.

    Science.gov (United States)

    Wilson, M. F.; Ninomiya, I.; Franz, G. N.; Judy, W. V.

    1971-01-01

    The basal level of mean renal nerve activity (MRNA-0) measured in anesthetized cats was found to be modified by the additive interaction of hypothalamic and baroceptor reflex influences. Data were collected with the four major baroceptor nerves either intact or cut, and with mean aortic pressure (MAP) either clamped with a reservoir or raised with l-epinephrine. With intact baroceptor nerves, MRNA stayed essentially constant at level MRNA-0 for MAP below an initial pressure P1, and fell approximately linearly to zero as MAP was raised to P2. Cutting the baroceptor nerves kept MRNA at MRNA-0 (assumed to represent basal central neural output) independent of MAP. The addition of hypothalamic stimulation produced nearly constant increments in MRNA for all pressure levels up to P2, with complete inhibition at some level above P2. The increments in MRNA depended on frequency and location of the stimulus. A piecewise linear model describes MRNA as a linear combination of hypothalamic, basal central neural, and baroceptor reflex activity.

  13. Modulation of the startle reflex by pleasant and unpleasant music.

    Science.gov (United States)

    Roy, Mathieu; Mailhot, Jean-Philippe; Gosselin, Nathalie; Paquette, Sébastien; Peretz, Isabelle

    2009-01-01

    The issue of emotional feelings to music is the object of a classic debate in music psychology. Emotivists argue that emotions are really felt in response to music, whereas cognitivists believe that music is only representative of emotions. Psychophysiological recordings of emotional feelings to music might help to resolve the debate, but past studies have failed to show clear and consistent differences between musical excerpts of different emotional valence. Here, we compared the effects of pleasant and unpleasant musical excerpts on the startle eye blink reflex and associated body markers (such as the corrugator and zygomatic activity, skin conductance level and heart rate). The startle eye blink amplitude was larger and its latency was shorter during unpleasant compared with pleasant music, suggesting that the defensive emotional system was indeed modulated by music. Corrugator activity was also enhanced during unpleasant music, whereas skin conductance level was higher for pleasant excerpts. The startle reflex was the response that contributed the most in distinguishing pleasant and unpleasant music. Taken together, these results provide strong evidence that emotions were felt in response to music, supporting the emotivist stance.

  14. Adipose afferent reflex: sympathetic activation and obesity hypertension.

    Science.gov (United States)

    Xiong, X-Q; Chen, W-W; Zhu, G-Q

    2014-03-01

    Excessive sympathetic activity contributes to the pathogenesis of hypertension and the progression of the related organ damage. Adipose afferent reflex (AAR) is a sympatho-excitatory reflex that the afferent activity from white adipose tissue (WAT) increases sympathetic outflow and blood pressure. Hypothalamic paraventricular nucleus (PVN or PVH) is one of the central sites in the control of the AAR, and ionotropic glutamate receptors in the nucleus mediate the AAR. The AAR is enhanced in obesity and obesity hypertension. Enhanced WAT afferent activity and AAR contribute to the excessive sympathetic activation and hypertension in obesity. Blockage of the AAR attenuates the excessive sympathetic activity and hypertension. Leptin may be one of sensors in the WAT for the AAR, and is involved in the enhanced AAR in obesity and hypertension. This review focuses on the neuroanatomical basis and physiological functions of the AAR, and the important role of the enhanced AAR in the pathogenesis of obesity hypertension. © 2013 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  15. Agency, reflexivity and risk: cosmopolitan, neurotic or prudential citizen?

    Science.gov (United States)

    Walklate, Sandra; Mythen, Gabriel

    2010-03-01

    The purpose of this paper is to critically examine the turn to risk within sociology and to survey the relationship between structure and agency as conceived by popular strands of risk theorizing. To this end, we appraise the risk society, culture of fear and governmentality perspectives and we consider the different imaginings of the citizen constructed by each of these approaches. The paper goes on to explore what each of these visions of citizenship implies for understandings of the structure/agency dynamic as it pertains to the question of reflexivity. In order to transcend uni-dimensional notions of citizenship and to reinvigorate sociological debates about risk, we call for conceptual analyses that are contextually rooted. Exampling the importance of knowledge contests around contemporary security threats and warnings of the deleterious effects of pre-emptive modes of regulation that derive from the 'risk turn' within social science, we argue for a more nuanced embrace of reflexivity within risk theorising in order to facilitate a more dynamic critique of the images of citizenship that such theorizing promotes.

  16. Revisiting global body politics in Nepal: A reflexive analysis.

    Science.gov (United States)

    Harcourt, Wendy

    2016-01-01

    Using the example of a human rights training in Nepal, the author looks at global body politics in a reflexive piece on her engagement in development practices that translate western feminist ideas on gender inequality and empowerment via UN human rights policies into non-western contexts. It firsts look at postcolonial and critical literature on feminist engagement in gender and development processes including a discussion on the concept of global body politics before examining briefly the framing of gender-based violence in Nepal. The core of the paper is a reflexive analysis and interrogation of the training in Nepal in order to bring out the tensions and contradictions around western developmental, feminist and human rights discourses. The discussion looks at how difficult it is for feminist, human rights and developmental discourses and practices to unmoor themselves from the notion of the 'expert' and those who do the rights/work/righting rights training and those who are perennially seen as requiring training. The conclusion reflects on possibilities of other epistemic practices found in intercultural dialogues.

  17. Deficits in reflexive covert attention following cerebellar injury.

    Directory of Open Access Journals (Sweden)

    Christopher eStriemer

    2015-08-01

    Full Text Available Traditionally the cerebellum has been known for its important role in coordinating motor output. Over the past fifteen years numerous studies have indicated that the cerebellum plays a role in a variety of cognitive functions including working memory, language, perceptual functions, and emotion. In addition, recent work suggests that regions of the cerebellum involved in eye movements also play a role in controlling covert visual attention. Here we investigated whether regions of the cerebellum that are not strictly tied to the control of eye movements might also contribute to covert attention. To address this question we examined the effects of circumscribed cerebellar lesions on reflexive covert attention in a group of patients (n=11 without any gross motor or oculomotor deficits, and compared their performance to a group of age-matched controls (n=11. Results indicated that the traditional RT advantage for validly cued targets was significantly smaller at the shortest (50ms SOA for cerebellar patients compared to controls. Critically, a lesion overlap analysis indicated that this deficit in the rapid deployment of attention was linked to damage in Crus I and Crus II of the lateral cerebellum. Importantly, both cerebellar regions have connections to non-motor regions of the prefrontal and posterior parietal cortices – regions important for controlling visuospatial attention. Together, these data provide converging evidence that both lateral and midline regions of the cerebellum play an important role in the control of reflexive covert visual attention.

  18. Deficits in reflexive covert attention following cerebellar injury.

    Science.gov (United States)

    Striemer, Christopher L; Cantelmi, David; Cusimano, Michael D; Danckert, James A; Schweizer, Tom A

    2015-01-01

    Traditionally the cerebellum has been known for its important role in coordinating motor output. Over the past 15 years numerous studies have indicated that the cerebellum plays a role in a variety of cognitive functions including working memory, language, perceptual functions, and emotion. In addition, recent work suggests that regions of the cerebellum involved in eye movements also play a role in controlling covert visual attention. Here we investigated whether regions of the cerebellum that are not strictly tied to the control of eye movements might also contribute to covert attention. To address this question we examined the effects of circumscribed cerebellar lesions on reflexive covert attention in a group of patients (n = 11) without any gross motor or oculomotor deficits, and compared their performance to a group of age-matched controls (n = 11). Results indicated that the traditional RT advantage for validly cued targets was significantly smaller at the shortest (50 ms) SOA for cerebellar patients compared to controls. Critically, a lesion overlap analysis indicated that this deficit in the rapid deployment of attention was linked to damage in Crus I and Crus II of the lateral cerebellum. Importantly, both cerebellar regions have connections to non-motor regions of the prefrontal and posterior parietal cortices-regions important for controlling visuospatial attention. Together, these data provide converging evidence that both lateral and midline regions of the cerebellum play an important role in the control of reflexive covert visual attention.

  19. Intraurethral stimulation evokes bladder responses via 2 distinct reflex pathways.

    Science.gov (United States)

    Woock, John P; Yoo, Paul B; Grill, Warren M

    2009-07-01

    Recent animal studies have shown that selective activation of pudendal nerve branches can evoke bladder responses through 2 distinct reflex pathways. We examined intraurethral electrical stimulation as a minimally invasive means of selectively activating these pathways in the cat. Bladder responses evoked by intraurethral electrical stimulation were measured in alpha-chloralose anesthetized male cats at different stimulation frequencies, stimulation intensities and intraurethral locations. Intraurethral electrical stimulation evoked inhibitory and excitatory bladder reflexes depending on stimulation frequency and location. Stimulation in the penile urethra 0 to 3 cm from the urethral meatus at 33 Hz evoked bladder contraction and at 10 Hz it evoked bladder relaxation. These responses were abolished after bilateral transection of the dorsal penile nerves. Stimulation in the membranous urethra 5 to 7 cm from the urethral meatus at 2, 10 and 33 Hz evoked bladder contractions. These responses were abolished after bilateral transection of the cranial sensory nerves. Following acute spinal cord transection bladder contractions were still evoked by 33 Hz stimulation in the penile urethra but not by stimulation at any frequency in the membranous urethra. Intraurethral electrical stimulation selectively evoked bladder responses by activating 2 distinct pudendal afferent pathways. Responses depended on stimulation frequency and location. Intraurethral electrical stimulation is a valid means of determining the pathways involved in bladder responses evoked by pudendal nerve stimulation.

  20. Researching Reflexively With Patients and Families: Two Studies Using Video-Reflexive Ethnography to Collaborate With Patients and Families in Patient Safety Research.

    Science.gov (United States)

    Collier, Aileen; Wyer, Mary

    2016-06-01

    Patient safety research has to date offered few opportunities for patients and families to be actively involved in the research process. This article describes our collaboration with patients and families in two separate studies, involving end-of-life care and infection control in acute care. We used the collaborative methodology of video-reflexive ethnography, which has been primarily used with clinicians, to involve patients and families as active participants and collaborators in our research. The purpose of this article is to share our experiences and findings that iterative researcher reflexivity in the field was critical to the progress and success of each study. We present and analyze the complexities of reflexivity-in-the-field through a framework of multilayered reflexivity. We share our lessons here for other researchers seeking to actively involve patients and families in patient safety research using collaborative visual methods. © The Author(s) 2015.