Sample records for conditioned reflexes

  1. INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES

    E-print Network

    Sega, Liana - Department of Mathematics and Statistics, University of Missouri

    INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES DAVID A. JORGENSEN AND LIANA M. S¸EGA Abstract. We show that the conditions defining total reflexivity for modules are independent. In particular and the canonical map M M is bijective. A finite R-module M is said to be totally reflexive if it satisfies

  2. [The development of I. P. Pavlov's conditioned reflex theory].

    PubMed

    Kim, O J

    1992-01-01

    This paper deals with the theory of Ivan Petrovich Pavlov (1849-1936), a Russian physiologist who presented for the first time the systematic theory of the function of the brain that controls the whole behavior of animals, i.e. higher nervous activity through experimental studies. This paper, principally based on Lectures on Conditioned Reflexes (1928), investigates the development of conditioned reflex theory from its beginning by dividing it into three periods. First, during the period from 1898 to 1906, the fundamental concept of conditioned reflex was established and the study of conditioned reflex became an independent discipline. From 1907 to 1916, the second period, Pavlov theorized on higher nervous activity on the basis of extensive data from his laboratory experiments of conditioned reflex. And Pavlov complemented conditioned reflex theory, during the third period from 1916 to 1928, and extended the boundaries of it through applications of conditioned reflex theory to psychopathology and typology. The study contributes to the understanding that conditioned reflex theory was historically developed, and not presented as a complete form from the beginning, and that Pavlov intended to study the higher nervous activity through the method of neurophysiology. PMID:11618531

  3. INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES

    E-print Network

    Sega, Liana - Department of Mathematics and Statistics, University of Missouri

    INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES DAVID A. JORGENSEN AND LIANA M. S,EGA Abstract.We show that the conditions defining total if it is finite and the cano* *nical map M ! M** is bijective. A finite R-module M is said to be totally

  4. Associative Mechanosensory Conditioning of the Proboscis Extension Reflex in Honeybees

    ERIC Educational Resources Information Center

    Giurfa, Martin; Malun, Dagmar

    2004-01-01

    The present work introduces a form of associative mechanosensory conditioning of the proboscis extension reflex (PER) in honeybees. In our paradigm, harnessed honeybees learn the elemental association between mechanosensory, antennal stimulation and a reward of sucrose solution delivered to the proboscis. Thereafter, bees extend their proboscis to…

  5. Reflex conditioning: A new strategy for improving motor function after spinal cord injury

    PubMed Central

    Chen, Xiang Yang; Chen, Yi; Wang, Yu; Thompson, Aiko; Carp, Jonathan S.; Segal, Richard L.; Wolpaw, Jonathan R.

    2010-01-01

    Spinal reflex conditioning changes reflex size, induces spinal cord plasticity, and modifies locomotion. Appropriate reflex conditioning can improve walking in rats after spinal cord injury (SCI). Reflex conditioning offers a new therapeutic strategy for restoring function in people with SCI. This approach can address the specific deficits of individuals with SCI by targeting specific reflex pathways for increased or decreased responsiveness. In addition, once clinically significant regeneration can be achieved, reflex conditioning could provide a means of re-educating the newly (and probably imperfectly) reconnected spinal cord. PMID:20590534

  6. Conditioning of the H reflex by stimulation of the posterior tibial nerve in Parkinson's disease.

    PubMed Central

    Martinelli, P; Montagna, P

    1979-01-01

    The excitability curve of the H reflex conditioned by stimulation of a mixed nerve was studied in eight Parkinsonism patients, before and after L-dopa therapy. There was no significant variation between the two curves. However, there was a reduction of the normal early inhibition of the H reflex conditioned by exteroceptive stimulation. This indicates the presence of alterations in the organisation of the reflex pathways at a spinal level in this disease. PMID:490175

  7. Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury

    PubMed Central

    Chen, Yi; Chen, Lu; Liu, Rongliang; Wang, Yu; Wolpaw, Jonathan R.

    2013-01-01

    When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a “negotiated equilibrium” that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery. PMID:24371288

  8. Reliability of subjective pain ratings and nociceptive flexion reflex responses as measures of conditioned pain modulation

    PubMed Central

    Jurth, Carlo; Rehberg, Benno; von Dincklage, Falk

    2014-01-01

    BACKGROUND: The endogenous modulation of pain can be assessed through conditioned pain modulation (CPM), which can be quantified using subjective pain ratings or nociceptive flexion reflexes. However, to date, the test-retest reliability has only been investigated for subjective pain ratings. OBJECTIVE: To compare the test-retest reliability of CPM-induced changes, measured using subjective pain ratings and nociceptive flexion reflexes, to provide a reliable scoring parameter for future studies. METHOD: A total of 40 healthy volunteers each received painful electrical stimuli to the sural nerve to elicit nociceptive flexion reflexes. Reflex sizes and subjective pain ratings were recorded before and during the immersion of the contralateral hand in hot water to induce CPM as well as innocuous water as control. Measurements were repeated in a retest 28 days later. RESULTS: Intraclass correlation coefficients showed good test-retest reliabilities of CPM during the hot water stimulus for both scoring parameters. Subjective pain ratings also correlated between test and retest during the control stimulus. CONCLUSIONS: Subjective pain ratings and nociceptive flexion reflexes show comparable test-retest reliabilities, but they reflect different components of CPM. While subjective pain ratings appear to incorporate cognitive influences to a larger degree, reflex responses appear to reflect spinal nociception more purely. PMID:24555177

  9. The Simplest Motor Skill: Mechanisms and Applications of Reflex Operant Conditioning

    PubMed Central

    Thompson, Aiko K.; Wolpaw, Jonathan R.

    2014-01-01

    Operant conditioning protocols can gradually change spinal reflexes, which are the simplest behaviors. This article summarizes the evidence supporting two propositions: that these protocols provide excellent models for defining the substrates of learning; and that they can induce and guide plasticity to help restore skills such as locomotion that have been impaired by spinal cord injury or other disorders. PMID:24508738

  10. Associative Mechanosensory Conditioning of the Proboscis Extension Reflex in Honeybees

    E-print Network

    Menzel, Randolf - Institut für Biologie

    stimulus or CS) with a reward of sucrose so- lution (unconditioned stimulus or US) delivered to their anten), animals learn that an originally neutral stimulus (conditioned stimulus, CS) can act as a predictor for a biologically significant stimulus (un- conditioned stimulus, US). In operant conditioning (Skinner 1938

  11. Conditioning effect in single human motoneurones: a new method using the unitary H reflex.

    PubMed Central

    Shindo, M; Yanagawa, S; Morita, H; Hashimoto, T

    1994-01-01

    1. A new method for the study of spinal reflexes using single motor units is described. 2. The excitability of a motoneurone is assessed as the 'critical firing stimulus' (CFS), which is the difference between the test stimulus intensity needed to reach the threshold for the lowest threshold Ia fibres and the intensity which evokes firing of a motor unit with the probability of 50% (FP50%). The intensity with FP50% is obtained by modulating stimulator output. When the motor unit is fired by a stimulus, the next intensity is decreased, and vice versa. The Ia threshold is defined as the threshold for homonymous monosynaptic peaks in PSTHs during contraction of the muscle examined. 3. A conditioning effect is represented as a change in CFS, the extent being expressed as a percentage of the unconditioned CFS. 4. Effects obtained by conditioning stimulation with the new and conventional H reflex methods are compared. The sensitivities are almost the same and the extents of the effects have highly correlated linear relations for the two methods. 5. The advantages of the new method are (1) that it shows reflex activities on a single motoneurone, (2) that it is applicable both to muscles at rest and during contraction, and (3) that it quantifies conditioning effects as percentages of the size of test Ia EPSPs. PMID:7738838

  12. [Conditioned reflex changes in the functional connections between adjacent and remote cortical neurons].

    PubMed

    Galashina, A G; Bogdanov, A V

    1981-01-01

    A motor conditioned reflex to sound was elaborated in cats with electrodes (nichrome wire dia 50 mcm) chronically implanted in the auditory cortex. Multineuronal activity preceding by 30 s the conditioned signal was analysed. Impulse activity of two to three neurones was isolated from every record by means of an amplitude discriminator. Dependence between impulse series isolated either from one record or from records obtained with two electrodes placed at a distance of up to 200 mcm from one another, was estimated by crossover interval histograms. Consequently functional connections between neurones were defined by the dependence of impulse series. In the process of conditioning dynamic reorganization of interneuronal connections was revealed. With a stable reflex, the number of connections both between neurons in the microregion and between neurones of neighbouring microregions considerably increased due to an increased number of excitatory connections. After extinction of the reflex, the number of connections between adjacent neurons increased still more, though due to enhancement of the inhibitory type connections. Nonetheless, excitatory connections kept dominating. At the same time, the number of connections between neurons of the neighbouring microsystems sharply decreased. PMID:7281994

  13. The Cerebellum in Maintenance of a Motor Skill: A Hierarchy of Brain and Spinal Cord Plasticity Underlies H-Reflex Conditioning

    ERIC Educational Resources Information Center

    Wolpaw, Jonathan R.; Chen, Xiang Yang

    2006-01-01

    Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, is a simple model of skill acquisition and involves plasticity in the spinal cord. Previous work showed that the cerebellum is essential for down-conditioning the H-reflex. This study asks whether the cerebellum is also essential for maintaining…

  14. Infant reflexes

    MedlinePLUS

    ... Moro reflex Sucking reflex (sucks when area around mouth is touched). Startle reflex (pulling arms and legs in after hearing loud noise). Step reflex (stepping motions when sole of foot touches hard surface). Other infant reflexes include: Tonic ...

  15. Enhanced D1 and D2 Inhibitions Induced by Low-Frequency Trains of Conditioning Stimuli: Differential Effects on H- and T-Reflexes and Possible Mechanisms

    PubMed Central

    Mezzarane, Rinaldo André; Magalhães, Fernando Henrique; Chaud, Vitor Martins; Elias, Leonardo Abdala; Kohn, André Fabio

    2015-01-01

    Mechanically evoked reflexes have been postulated to be less sensitive to presynaptic inhibition (PSI) than the H-reflex. This has implications on investigations of spinal cord neurophysiology that are based on the T-reflex. Preceding studies have shown an enhanced effect of PSI on the H-reflex when a train of ~10 conditioning stimuli at 1 Hz was applied to the nerve of the antagonist muscle. The main questions to be addressed in the present study are if indeed T-reflexes are less sensitive to PSI and whether (and to what extent and by what possible mechanisms) the effect of low frequency conditioning, found previously for the H-reflex, can be reproduced on T-reflexes from the soleus muscle. We explored two different conditioning-to-test (C-T) intervals: 15 and 100 ms (corresponding to D1 and D2 inhibitions, respectively). Test stimuli consisted of either electrical pulses applied to the posterior tibial nerve to elicit H-reflexes or mechanical percussion to the Achilles tendon to elicit T-reflexes. The 1 Hz train of conditioning electrical stimuli delivered to the common peroneal nerve induced a stronger effect of PSI as compared to a single conditioning pulse, for both reflexes (T and H), regardless of C-T-intervals. Moreover, the conditioning train of pulses (with respect to a single conditioning pulse) was proportionally more effective for T-reflexes as compared to H-reflexes (irrespective of the C-T interval), which might be associated with the differential contingent of Ia afferents activated by mechanical and electrical test stimuli. A conceivable explanation for the enhanced PSI effect in response to a train of stimuli is the occurrence of homosynaptic depression at synapses on inhibitory interneurons interposed within the PSI pathway. The present results add to the discussion of the sensitivity of the stretch reflex pathway to PSI and its functional role. PMID:25807195

  16. EVIDENCE FOR THE INVOLVEMENT OF ASSOCIATIVE CONDITIONING IN REFLEX MODIFICATION OF THE ACOUSTIC STARTLE RESPONSE WITH GAPS IN BACKGROUND NOISE

    EPA Science Inventory

    The experiments reported here were designed to determine the role of associative conditioning in reflex modification of the acoustic startle response using gaps in background noise. xperiments were conducted with independent, naive groups of adult Long Evans hooded rats tested us...

  17. SENSORI-SENSORY AFFERENT CONDITIONING WITH LEG MOVEMENT: GAIN CONTROL IN SPINAL REFLEX AND ASCENDING PATHS

    Microsoft Academic Search

    J. D BROOKE; J CHENG; D. F COLLINS; W. E MCILROY; J. E MISIASZEK; W. R STAINES

    1997-01-01

    Studies are reviewed, predominantly involving healthy humans, on gain changes in spinal reflexes and supraspinal ascending paths during passive and active leg movement. The passive movement research shows that the pathways of H reflexes of the leg and foot are down-regulated as a consequence of movement-elicited discharge from somatosensory receptors, likely muscle spindle primary endings, both ipsi- and contralaterally. Discharge

  18. [Principle of least action, physiology of vision, and conditioned reflexes theory].

    PubMed

    Shelepin, Iu E; Krasil'nikov, N N

    2003-06-01

    The variation principles such as principle of least action by Maupertuis (1740) and Fermat principle (1660) are fundamental for physics. They permit to establish a property by which the actual state is differing from all possible states of the system. The variation approach permits to establish equation of motion and equilibrium of a material system on the basis of one common rule which reduces to the search of the function extremes, describes this property of the system. So for the optical systems, crucial is the time and not the length of the way. According to Fermat principles, the light "choosen" from all possible ways connects two dots in the way which needs the least time. Generality of the variation principles guarantees success of their use in brain function investigations. Between different attempts to apply the variation principles to psychology and linguistics, the Zipf principle of least effort must be distinguished. Zipf (1949) demonstrated that languages and some artificial codes satisfied the least principle. For the brain physiology, classical conditioned reflex theory is the ideal area of variation principles application. According to this approach, conditioning leads to finding the extreme during fixation of the temporal link. In vision, physiological investigations are difficult because the signal has many dimensions. For example, during perception of spatial properties of surrounding world, in vision is realized minimization (reduction) of spatial-frequency spectrum of the scene. The receptive fields provide optimal accumulation of the signal. In ontogenesis, signal--noise ratio becomes optimal as receptive fields minimized the internal noise spectrum. According to the theory of match filtration, in the visual system recognition is carryied out by minimal differences between the image description in the visual system and storage in the human memory template of that image. The variation principles help to discover the physical property of phenomenon. The law discovered for mechanical system may be translated to quantum level. In physiology, variation principles permit us to connect information approach with concrete physiological mechanisms of pattern recognition and conditioned reflex. PMID:12966710

  19. Aversive learning in honeybees revealed by the olfactory conditioning of the sting extension reflex.

    PubMed

    Vergoz, Vanina; Roussel, Edith; Sandoz, Jean-Christophe; Giurfa, Martin

    2007-01-01

    Invertebrates have contributed greatly to our understanding of associative learning because they allow learning protocols to be combined with experimental access to the nervous system. The honeybee Apis mellifera constitutes a standard model for the study of appetitive learning and memory since it was shown, almost a century ago, that bees learn to associate different sensory cues with a reward of sugar solution. However, up to now, no study has explored aversive learning in bees in such a way that simultaneous access to its neural bases is granted. Using odorants paired with electric shocks, we conditioned the sting extension reflex, which is exhibited by harnessed bees when subjected to a noxious stimulation. We show that this response can be conditioned so that bees learn to extend their sting in response to the odorant previously punished. Bees also learn to extend the proboscis to one odorant paired with sugar solution and the sting to a different odorant paired with electric shock, thus showing that they can master both appetitive and aversive associations simultaneously. Responding to the appropriate odorant with the appropriate response is possible because two different biogenic amines, octopamine and dopamine subserve appetitive and aversive reinforcement, respectively. While octopamine has been previously shown to substitute for appetitive reinforcement, we demonstrate that blocking of dopaminergic, but not octopaminergic, receptors suppresses aversive learning. Therefore, aversive learning in honeybees can now be accessed both at the behavioral and neural levels, thus opening new research avenues for understanding basic mechanisms of learning and memory. PMID:17372627

  20. The Grasp Reflex and Moro Reflex in Infants: Hierarchy of Primitive Reflex Responses

    PubMed Central

    Futagi, Yasuyuki; Toribe, Yasuhisa; Suzuki, Yasuhiro

    2012-01-01

    The plantar grasp reflex is of great clinical significance, especially in terms of the detection of spasticity. The palmar grasp reflex also has diagnostic significance. This grasp reflex of the hands and feet is mediated by a spinal reflex mechanism, which appears to be under the regulatory control of nonprimary motor areas through the spinal interneurons. This reflex in human infants can be regarded as a rudiment of phylogenetic function. The absence of the Moro reflex during the neonatal period and early infancy is highly diagnostic, indicating a variety of compromised conditions. The center of the reflex is probably in the lower region of the pons to the medulla. The phylogenetic meaning of the reflex remains unclear. However, the hierarchical interrelation among these primitive reflexes seems to be essential for the arboreal life of monkey newborns, and the possible role of the Moro reflex in these newborns was discussed in relation to the interrelationship. PMID:22778756

  1. Effect of electrical stimulation of the somatosensory cortex and caudate nucleus on extinctive inhibition of a food conditioned reflex to sound

    Microsoft Academic Search

    A. S. Denisova

    1981-01-01

    Conclusions 1.During stimulation of the somatosensory and motor cortex (areas Prc2 and Prc1) and of the ventrolateral zone of the head of the caudate nucleus, extinction of the food reflex is accelerated and deepened.2.Stimulation of the anterolateral gyrus (area Pc1) of the cortex and the central zone of the head of the caudate nucleus delays extinction of the conditioned reflex.3.Stimulation

  2. Caring Reflexivity

    ERIC Educational Resources Information Center

    Rallis, Sharon F.; Rossman, Gretchen B.

    2010-01-01

    This article provides a brief summary of the seven articles in this special issue through the lens of the concept of "caring reflexivity". In joining "caring" and "reflexivity", we deepen the conversation about what constitutes reflexivity, encouraging an explicit focus on the relational. Revisiting the first article, we argue that…

  3. Fear conditioning facilitates rats gap detection measured by prepulse inhibition of the startle reflex

    NASA Astrophysics Data System (ADS)

    Zou, Dan; Wu, Xihong; Li, Liang

    2005-04-01

    A low-intensity acoustic event presented shortly before an intense startling sound can inhibit the acoustic startle reflex. This phenomenon is called prepulse inhibition (PPI), and is widely used as a model of sensorimotor gating in both humans and animals. Particularly, it has been used for evaluating the aging effect on the mouse's ability to detect a silent gap in otherwise continuous sounds. The present study extended this model to the emotional modulation of gap detection. The results show that a silent gap embedded in each of the two broadband noise sounds (55 dB SPL), which were delivered by two spatially separated loudspeakers, could inhibit the startle reflex that was induced by a loud sound presented from the third loudspeaker 50 ms after the gap. The inhibitory effect largely depended on the duration of the gap, with the mean duration threshold around 11 ms across 18 rats tested. Pairing the gap with foot shock in a temporally specific manner, but not in a temporally random manner, significantly reduced the duration threshold. Thus this study established a new animal behavioral model both for studying auditory temporal processing and for studying auditory signal-detection plasticity induced by emotional learning.

  4. Comparison of the classically conditioned withdrawal reflex in cerebellar patients and healthy control subjects during stance: 2. Biomechanical characteristics.

    PubMed

    Kutz, D F; Kaulich, Th; Föhre, W; Gerwig, M; Timmann, D; Kolb, F P

    2014-03-01

    This study addresses cerebellar involvement in classically conditioned nociceptive lower limb withdrawal reflexes in standing humans. A preceding study compared electromyographic activities in leg muscles of eight patients with cerebellar disease (CBL) and eight age-matched controls (CTRL). The present study extends and completes that investigation by recording biomechanical signals from a strain-gauge-equipped platform during paired auditory conditioning stimuli (CS) and unconditioned stimuli (US) trials and during US-alone trials. The withdrawal reflex performance-lifting the stimulated limb (decreasing the vertical force from that leg, i.e. 'unloading') and transferring body weight to the supporting limb (increasing the vertical force from that leg, i.e. 'loading')-was quantified by the corresponding forces exerted onto the platform. The force changes were not simultaneous but occurred as a sequence of multiple force peaks at different times depending on the specific limb task (loading or unloading). Motor learning, expressed by the occurrence of conditioned responses (CR), is characterized by this sequence beginning already within the CSUS window. Loading and unloading were delayed and prolonged in CBL, resulting in incomplete rebalancing during the analysis period. Trajectory loops of the center of vertical pressure-derived from vertical forces-were also incomplete in CBL within the recording period. However, exposing CBL to a CS resulted in motor improvement reflected by shortening the time of rebalancing and by optimizing the trajectory loop. In summary, associative responses in CBL are not absent although they are less frequent and of smaller amplitude than in CTRL. PMID:24445111

  5. Honey bees (Apis mellifera) as explosives detectors: exploring proboscis extension reflex conditioned response to trinitrotolulene (TNT)

    SciTech Connect

    Taylor-mccabe, Kirsten J [Los Alamos National Laboratory; Wingo, Robert M [Los Alamos National Laboratory; Haarmann, Timothy K [Los Alamos National Laboratory

    2008-01-01

    We examined honey bee's associative learning response to conditioning with trinitrotolulene (TNT) vapor concentrations generated at three temperatures and their ability to be reconditioned after a 24 h period. We used classical conditioning of the proboscis extension (PER) in honey bees using TNT vapors as the conditioned stimulus and sucrose as the unconditioned stimulus. We conducted fifteen experimental trials with an explosives vapor generator set at 43 C, 25 C and 5 C, producing three concentrations of explosives (1070 ppt, 57 ppt, and 11 ppt). Our objective was to test the honey bee's ability to exhibit a conditioned response to TNT vapors at all three concentrations by comparing the mean percentage of honey bees successfully exhibiting a conditioned response within each temperature group. Furthermore, we conducted eight experimental trials to test the honey bee's ability to retain their ability to exhibit a conditioned response to TNT after 24h period by comparing the mean percentage of honey bees with a conditioned response TNT on the first day compared to the percentage of honey bees with a conditioned response to TNT on the second day. Results indicate that there was no significant difference between the mean percentage of honey bees with a conditioned response to TNT vapors between three temperature groups. There was a significant difference between the percentage of honey bees exhibiting conditioned response on the first day of training compared to the percentage of honey bees exhibiting conditioned response 24 h after training. Our experimental results indicate that honey bees can be trained to exhibit a conditioned response to a range of TNT concentrations via PER However, it appears that the honey bee's ability to retain the conditioned response to TNT vapors after 24h significantly decreases.

  6. Is the Conditioned Pain Modulation Paradigm Reliable? A Test-Retest Assessment Using the Nociceptive Withdrawal Reflex

    PubMed Central

    Biurrun Manresa, José A.; Fritsche, Raphael; Vuilleumier, Pascal H.; Oehler, Carmen; Mørch, Carsten D.; Arendt-Nielsen, Lars; Andersen, Ole K.; Curatolo, Michele

    2014-01-01

    The aim of this study was to determine the reliability of the conditioned pain modulation (CPM) paradigm assessed by an objective electrophysiological method, the nociceptive withdrawal reflex (NWR), and psychophysical measures, using hypothetical sample sizes for future studies as analytical goals. Thirty-four healthy volunteers participated in two identical experimental sessions, separated by 1 to 3 weeks. In each session, the cold pressor test (CPT) was used to induce CPM, and the NWR thresholds, electrical pain detection thresholds and pain intensity ratings after suprathreshold electrical stimulation were assessed before and during CPT. CPM was consistently detected by all methods, and the electrophysiological measures did not introduce additional variation to the assessment. In particular, 99% of the trials resulted in higher NWR thresholds during CPT, with an average increase of 3.4 mA (p<0.001). Similarly, 96% of the trials resulted in higher electrical pain detection thresholds during CPT, with an average increase of 2.2 mA (p<0.001). Pain intensity ratings after suprathreshold electrical stimulation were reduced during CPT in 84% of the trials, displaying an average decrease of 1.5 points in a numeric rating scale (p<0.001). Under these experimental conditions, CPM reliability was acceptable for all assessment methods in terms of sample sizes for potential experiments. The presented results are encouraging with regards to the use of the CPM as an assessment tool in experimental and clinical pain. Trial Registration: Clinical Trials.gov NCT01636440 PMID:24950186

  7. Ablation of Cerebellar Nuclei Prevents H-Reflex Down-Conditioning in Rats

    ERIC Educational Resources Information Center

    Chen, Xiang Yang; Wolpaw, Jonathan R.

    2005-01-01

    While studies of cerebellar involvement in learning and memory have described plasticity within the cerebellum, its role in acquisition of plasticity elsewhere in the CNS is largely unexplored. This study set out to determine whether the cerebellum is needed for acquisition of the spinal cord plasticity that underlies operantly conditioned

  8. Experimenting With Baroreceptor Reflexes

    NASA Technical Reports Server (NTRS)

    Eckberg, Dwain L.; Goble, Ross L.

    1988-01-01

    Carotid arteries stimulated by pressure or suction on neck. Baro-Cuff is silicone-rubber chamber that fits on front of subject's neck. Electronic system, stepping motor, bellows, and umbilical tube furnish controlled pressure to chamber. Pressure sensor provides feedback to microprocessor in electronic system. Developed to study blood-pressure-reflex responses of astronauts in outer space. Useful for terrestrial studies of patients with congestive heart failure, chronic diabetes mellitus, and other conditions in which blood-pressure-reflex controls behave abnormally.

  9. Spatial patterns of visual cortical fast EEG during conditioned reflex in a rhesus monkey.

    PubMed

    Freeman, W J; van Dijk, B W

    1987-10-01

    A preliminary assay was made of the existence of time-space coherence patterns of fast EEG activity in the visual cortex of a Rhesus monkey. The primary intent of the present study was to evaluate the similarities and differences in relation to the olfactory bulb, where such coherences have been described and have been demonstrated to be associated with behaviour. Segments 1.5 s in duration were recorded simultaneously without averaging from 16 to 35 subdural electrodes fixed over the left occipital lobe in an array 3.6 cm X 2.8 cm. Each segment was taken during the delivery of a visual conditioned stimulus (CS) and the performance of a conditioned response (CR) by a well-trained Rhesus monkey. The EEGs appeared chaotic with irregular bursts lasting 75-200 ms, resembling those in the olfactory EEG but with lower peak frequencies. Fourier spectra showed broad distributions of power resembling '1/f noise' with multiple peaks in the range of 20-40 Hz. Time intervals were selected where coherent activity seemed to be present at a number of electrodes. A dominant component waveform that was common to all channels was extracted by principal components analysis (PCA) of each segment. The distribution of the power of this component across the electrodes (the factor loadings) was used to describe the spatial pattern of the coherent cortical activity. Statistical analyses suggested that different patterns could be associated to the CS and the CR, as has been found in the olfactory system. These patterns remained stable over a 6 week recording interval. The patterns can be better discriminated, when the factor loadings of each channel are normalized to zero mean and unit variance, to discard a basic pattern of power distribution, which may reflect anatomical and electrode positioning factors that are related to behavioral information processing by the cortex. The wide spatial distribution of the common patterns found suggests that EEG patterns that manifest differing states of the visual cortex may also be accessible with scalp electrodes. PMID:3676788

  10. Chinese Reflexive Ziji: Syntactic Reflexes vs. Nonsyntactic Reflexes.

    ERIC Educational Resources Information Center

    Pollard, Carl; Xue, Ping

    1998-01-01

    Proposes that the distinction between syntactic and nonsyntactic use of reflexives is not necessarily one of lexical ambiguity, positing one type of referentially dependent element (reflexives) which have two options for being related to their antecedents (syntactic binding and discourse conference). The paper focuses on Chinese reflexive ziji and…

  11. Reflexives in Mohawk

    E-print Network

    Bonvillain, Nancy

    1994-01-01

    This paper presents an analysis of meanings and uses of two reflexive morphemes in Mohawk. ‘Reflexive’ –atat- is shown to have both reflexive and reciprocal meanings. It is also realized in kinship terms and in the transitive ...

  12. Wireless quantified reflex device

    NASA Astrophysics Data System (ADS)

    Lemoyne, Robert Charles

    The deep tendon reflex is a fundamental aspect of a neurological examination. The two major parameters of the tendon reflex are response and latency, which are presently evaluated qualitatively during a neurological examination. The reflex loop is capable of providing insight for the status and therapy response of both upper and lower motor neuron syndromes. Attempts have been made to ascertain reflex response and latency, however these systems are relatively complex, resource intensive, with issues of consistent and reliable accuracy. The solution presented is a wireless quantified reflex device using tandem three dimensional wireless accelerometers to obtain response based on acceleration waveform amplitude and latency derived from temporal acceleration waveform disparity. Three specific aims have been established for the proposed wireless quantified reflex device: 1. Demonstrate the wireless quantified reflex device is reliably capable of ascertaining quantified reflex response and latency using a quantified input. 2. Evaluate the precision of the device using an artificial reflex system. 3.Conduct a longitudinal study respective of subjects with healthy patellar tendon reflexes, using the wireless quantified reflex evaluation device to obtain quantified reflex response and latency. Aim 1 has led to the steady evolution of the wireless quantified reflex device from a singular two dimensional wireless accelerometer capable of measuring reflex response to a tandem three dimensional wireless accelerometer capable of reliably measuring reflex response and latency. The hypothesis for aim 1 is that a reflex quantification device can be established for reliably measuring reflex response and latency for the patellar tendon reflex, comprised of an integrated system of wireless three dimensional MEMS accelerometers. Aim 2 further emphasized the reliability of the wireless quantified reflex device by evaluating an artificial reflex system. The hypothesis for aim 2 is that the wireless quantified reflex device can obtain reliable reflex parameters (response and latency) from an artificial reflex device. Aim 3 synthesizes the findings relevant to aim 1 and 2, while applying the wireless accelerometer reflex quantification device to a longitudinal study of healthy patellar tendon reflexes. The hypothesis for aim 3 is that during a longitudinal evaluation of the deep tendon reflex the parameters for reflex response and latency can be measured with a considerable degree of accuracy, reliability, and reproducibility. Enclosed is a detailed description of a wireless quantified reflex device with research findings and potential utility of the system, inclusive of a comprehensive description of tendon reflexes, prior reflex quantification systems, and correlated applications.

  13. The vestibulosympathetic reflex in humans: neural interactions between cardiovascular reflexes

    NASA Technical Reports Server (NTRS)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    1. Over the past 5 years, there has been emerging evidence that the vestibular system regulates sympathetic nerve activity in humans. We have studied this issue in humans by using head-down rotation (HDR) in the prone position. 2. These studies have clearly demonstrated increases in muscle sympathetic nerve activity (MSNA) and calf vascular resistance during HDR. These responses are mediated by engagement of the otolith organs and not the semicircular canals. 3. However, differential activation of sympathetic nerve activity has been observed during HDR. Unlike MSNA, skin sympathetic nerve activity does not increase with HDR. 4. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes (i.e. barorereflexes and skeletal muscle reflexes) has shown an additive interaction for MSNA. 5. The additive interaction between the baroreflexes and vestibulosympathetic reflex suggests that the vestibular system may assist in defending against orthostatic challenges in humans by elevating MSNA beyond that of the baroreflexes. 6. In addition, the further increase in MSNA via otolith stimulation during isometric handgrip, when arterial pressure is elevated markedly, indicates that the vestibulosympathetic reflex is a powerful activator of MSNA and may contribute to blood pressure and flow regulation during dynamic exercise. 7. Future studies will help evaluate the importance of the vestibulosympathetic reflex in clinical conditions associated with orthostatic hypotension.

  14. Vestibular-Ocular Reflex

    NSDL National Science Digital Library

    2013-01-30

    In this activity, learners will perform various investigations to understand the vestibular-ocular reflex and learn about the importance of visual cues in maintaining balance. During the two-part activity, learners will compare the stability of a moving image under two conditions as well as compare the effects of rotation on the sensation of spinning under varying conditions. This lesson guide includes background information, review and critical thinking questions with answers, and handouts. Educators can also use this activity to discuss how the brain functions in space and how researchers study the vestibular function in space.

  15. Differential Effects ofNoxious Conditioning Stimulation oftheCheekbyCapsaicin onHumanSensory andInhibitory Masseter Reflex Responses Evoked byTooth PulpStimulation

    Microsoft Academic Search

    P. Kemppainenl; A. Waltimol; T. Waltimol; M. Kononen

    Inthis study, weinvestigated whether selective activation ofnociceptive primary afferent fibers bycapsaicin wouldinduce modulations ontooth-pulp-evoked sensory or inhibitory masseter reflex responses inhealthy humansubjects. Thecontribution ofcentral N-methyl-D-aspartate (NMDA) receptor mechanisms incapsaicin-induced effects onsensory or reflex responses wasevaluated bydextromethorphan, an NMDA-receptor antagonist. Theinhibitory masseter reflex was evoked byelectrical stimulation (constant current, single puLses) oftheupper incisor while thesubject wasbiting at10% ofhismaximalforce. Thesensation ofthetooth pulp

  16. Differential Effects of Noxious Conditioning Stimulation of the Cheek by Capsaicin on Human Sensory and Inhibitory Masseter Reflex Responses Evoked by Tooth Pulp Stimulation

    Microsoft Academic Search

    P. Kemppainen; A. Waltimo; T. Waltimo; M. Könönen; A. Pertovaara

    1997-01-01

    In this study, we investigated whether selective activation of nociceptive primary afferent fibers by capsaicin would induce modulations on tooth-pulp-evoked sensory or inhibitory masseter reflex responses in healthy human subjects. The contribution of central N-methyl-D-aspartate (NMDA) receptor mechanisms in capsaicin-induced effects on sensory or reflex responses was evaluated by dextromethorphan, an NMDA-receptor antagonist. The inhibitory masseter reflex was evoked by

  17. The Reflexes of the Fundus Oculi

    PubMed Central

    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 degeneration of the retina or after the subsidence of severe retinitis or retino-choroiditis. A mirror reflex from the layer of pigmented epithelium or from the external limiting membrane is sometimes recognizable in normal eyes, especially in the brunette fundus. In such, it forms the background to a striking picture of the fine circumfoveal vessels. Pathological reflexes from the level of the pigmented epithelium or of the external limiting membrane are also observed, and these often present a granular, frosted or crystalline appearance. They may indicate a senile change, or result from trauma or from retino-choroidal degeneraion. Somewhat similar reflexes may sometimes be present as small frosted patches anterior to the retinal vessels. Linear sinuous, whether appearing in annular form, as straight needles, as broader single sinuous lines, as the tapering, branched double reflexes of Vogt, or in association with traction or pressure folds, in the retina, are probably always pathological. By the use of selected light of long and short wave lengths, it can be shown that intraretinal or true retinal folds may exist with or without the surface reflexes which indicate a corresponding folding of the internal limiting membrane. On the other hand, superficial linear reflexes of various types may occur without evidence of retinal folding. Annular reflexes usually accompany a rounded elevation of the retina due to tumour, hæmorrhage or exudate, but may indicate the presence of rounded depressions; traction folds occur where there is choroido-retinal scarring, or in association with macular hole or cystic degeneraion at the macula; pressure folds in cases of orbital cyst, abscess or neoplasm; and the other linear reflexes in association with papillo-retinal œdema, for example, in retrobulbar neuritis, in hypertensive neuro-retinitis, in contusio bulbi and in anterior uveitis. Punctate reflexes, other than Gunn's dots, are also pathological. They may occur as one variety of “fragmented” surface reflexes, or as evidence of th

  18. Embodied Self-Reflexivity

    ERIC Educational Resources Information Center

    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…

  19. Instructions and the Orienting Reflex in "Semantic Conditioning" of the Galvanic Skin Response in an Innocuous Situation

    ERIC Educational Resources Information Center

    Pendery, Mary; Maltzman, Irving

    1977-01-01

    Concerns the effects of instructions on classical conditioning of the GSR (galvanic skin response). It demonstrates that verbal conditioning of the GSR can be obtained using an innocuous unconditioned stimulus (UCS). Discusses implications for theories of human classical conditioning. (Editor/RK)

  20. Inactivation of the Central Nucleus of the Amygdala Abolishes Conditioning-Specific Reflex Modification of the Rabbit (Oryctolagus

    E-print Network

    modification (CRM)--changes in the NMR to the unconditioned stimulus (US) when tested in the absence of the conditioned stimulus following classical conditioning. To examine the CE's role in acquisition and as an increase in the amplitude of the NMR to the unconditioned stim- ulus (US) following presentation

  1. Semantic Conditioning and Generalization of the Galvanic Skin Response-Orienting Reflex with Overt and Covert Activity

    ERIC Educational Resources Information Center

    Maltzman, Irving; And Others

    1977-01-01

    Uses an innocuous tone as the imperative stimulus, or unconditioned stimulus, as in a forewarned reaction time situation but with no overt response required. Evidence of conditioning and generalization to words is obtained. (Editor/RK)

  2. Astronomical Data Reduction Workflows with Reflex

    NASA Astrophysics Data System (ADS)

    Ballester, P.; Bramich, D.; Forchi, V.; Freudling, W.; Garcia-Dabó, C. E.; klein Gebbinck, M.; Modigliani, A.; Moehler, S.; Romaniello, M.

    2014-05-01

    Reflex (http://www.eso.org/reflex) is an environment that provides an easy and flexible way to reduce VLT/VLTI science data using the ESO. Its top-level functionalities are: (1) Reflex allows to graphically specify the sequence in which the data reduction steps are executed, including conditional stops, loops and conditional branches, (2) Reflex makes it easy to inspect the intermediate and final data products and to repeat selected processing steps to optimize the data reduction, (3) the data organization necessary to reduce the data is built into the system and is fully automatic, (4) advanced users can plug-in their own Python or IDL modules and steps into the data reduction sequence, and (5) Reflex supports the development of data reduction workflows based on the ESO Common Pipeline Library. Reflex is based on the concept of a scientific workflow, whereby the data reduction cascade is rendered graphically and data seamlessly flow from one processing step to the next. It is distributed with a number of complete test datasets so that users can immediately start experimenting and familiarize themselves with the system (http://www.eso.org/pipelines). In this demo, we present the latest version of Reflex and its applications for astronomical data reduction processes.

  3. Reflecting on Human Reflexes

    NSDL National Science Digital Library

    2014-09-18

    Students learn about human reflexes, how our bodies react to stimuli and how some body reactions and movements are controlled automatically, without thinking consciously about the movement or responses. In the associated activity, students explore how reflexes work in the human body by observing an involuntary human reflex and testing their own reaction times using dominant and non-dominant hands. Once students understand the stimulus-to-response framework components as a way to describe human reflexes and reactions in certain situations, they connect this knowledge to how robots can be programmed to conduct similar reactions.

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

    PubMed

    Ghosh, Arko; Haggard, Patrick

    2014-01-01

    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. However, the presence of voluntary movement significantly impairs reflex perception. We suggest that perceptual separation between voluntary and reflex movement is poor at best. Our results imply that the brain has no clear marker for perceptually separating voluntary and involuntary movement. Attribution of body movement to voluntary or involuntary motor commands is surprisingly poor when both are present. PMID:24060990

  5. Classical Conditioning Components of the Orienting Reflex to Words Using Innocuous and Noxious Unconditioned Stimuli Under Different Conditioned Stimulus-Unconditioned Stimulus Intervals

    ERIC Educational Resources Information Center

    Maltzman, Irving; And Others

    1977-01-01

    Concerns the examination of conditioned stimulus--unconditioned stimulus (CS--UCS) intervals of different lengths. Demonstrates the feasibility of using a forewarned reaction time procedure with an innocuous imperative stimulus for the investigation of classical conditioning. (Editor/RK)

  6. Comparison of the sensitivity of prepulse inhibition of the startle reflex and operant conditioning in an auditory intensity difference limen paradigm.

    PubMed

    Behrens, Derik; Klump, Georg M

    2015-03-01

    Reward-based operant conditioning (OC) procedures and reflex-based prepulse inhibition (PPI) procedures are used in mouse psychoacoustics. Therefore it is important to know whether both procedures provide comparable results for perceptual measurements. Here we evaluate the sensitivity of the C57BL/6N mouse in both procedures by testing the same individuals in the same Intensity Difference Limen (IDL) task. Level increments of a 10 kHz tone were presented in a train of 10 kHz reference tones. Objective analysis based on signal-detection theory was applied to compare the results of OC and PPI procedures. In both procedures the sensitivity increased with level increment. In agreement with the near miss to Weber's law, sensitivity increased with sound level of the reference stimuli. The sensitivity observed in the OC procedure was considerably larger than the sensitivity in the PPI procedure. Applying a sensitivity of 1.0 as the threshold criterion, mean IDLs in the OC procedure were 5.0, 4.0 and 3.5 dB at reference levels of 30, 50 and 75 dB SPL respectively. In the PPI procedure, mean IDLs of 18.9 and 17.0 dB at reference levels of 50 and 75 dB SPL respectively were observed. Due to the low sensitivity, IDLs could not be determined in the PPI procedure at a reference level of 30 dB SPL. Possible causes for the low sensitivity in the PPI procedure are discussed. These results challenge the idea that both procedures can be used as simple substitutes of one another and the experimenter must be aware of the limitations of the respective procedure. PMID:25580004

  7. On Reflexive Data Models

    SciTech Connect

    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.

  8. Using stimulus frequency otoacoustic emissions to study basic properties of the human medial olivocochlear reflex

    E-print Network

    Backus, Bradford Clark

    2005-01-01

    The medial olivocochlear reflex (MOCR) is a brainstem-based neural feedback circuit by which mammals adaptively adjust the gain of their ears in response to changing environmental conditions. Activating the reflex with ...

  9. From Reflexive to Passive

    E-print Network

    Sohn, Joong-Sun

    1998-01-01

    Previous approaches to the passive development from a reflexive marking focus on how the former is similar to the latter semantically and syntactically. I show that the passive evolution is better understood by looking at ...

  10. Gamma butyrolactone (GBL) and gamma valerolactone (GVL): similarities and differences in their effects on the acoustic startle reflex and the conditioned enhancement of startle in the rat.

    PubMed

    Marinetti, Laureen J; Leavell, Bonita J; Jones, Calleen M; Hepler, Bradford R; Isenschmid, Daniel S; Commissaris, Randall L

    2012-06-01

    Gamma butyrolactone (GBL) is metabolized to gamma hydroxybutyrate (GHB) in the body. GHB is a DEA Schedule 1 compound; GBL is a DEA List 1 chemical. Gamma valerolactone (GVL) is the 4-methyl analog of GBL; GVL is metabolized to 4-methyl-GHB; GVL is NOT metabolized to GBL or GHB. The effects of GBL (18.75-150 mg/kg), GVL (200-1600 mg/kg) or vehicle on the acoustic startle reflex (ASR), and the classically-conditioned enhancement of startle, the Startle Anticipated Potentiation of Startle (SAPS) response were studied in male rats. Both compounds produced a dose-dependent reduction of ASR, with GBL 5-7 times more potent than GVL. In contrast, GBL treatment significantly reduced SAPS at doses that exerted only moderate effects on ASR, whereas GVL exerted little or no effect on the SAPS, except at doses that produced pronounced reductions in Noise Alone ASR. In a second experiment, rats were tested for Noise Alone ASR behavior following treatment with a single mid-range dose of GBL (75 mg/kg), GVL (400mg/kg) or vehicle; immediately following startle testing the animals were sacrificed and their brains and blood were collected for determination of GHB, 4-methyl-GHB, GBL and GVL. GHB was found in measurable concentrations in all of the blood specimens and 6 (of 8) of the brain specimens from the GBL-treated subjects. 4-Methyl-GHB was found in measurable concentrations in all of the blood and brain specimens of the GVL-treated subjects; the change in startle amplitude was inversely correlated to the brain concentrations of these compounds. These findings confirm the differences in the metabolic fate of GBL and GVL as pro-drugs for the formation of GHB and 4-methyl-GHB, respectively. Moreover, the dissimilarity in effect profile for GBL and GVL on ASR versus SAPS behaviors suggests that different receptor(s) may be involved in mediating these behavioral effects. PMID:22349589

  11. Anatomy and neuro-pathophysiology of the cough reflex arc

    PubMed Central

    2012-01-01

    Coughing is an important defensive reflex that occurs through the stimulation of a complex reflex arc. It accounts for a significant number of consultations both at the level of general practitioner and of respiratory specialists. In this review we first analyze the cough reflex under normal conditions; then we analyze the anatomy and the neuro-pathophysiology of the cough reflex arc. The aim of this review is to provide the anatomic and pathophysiologic elements of evaluation of the complex and multiple etiologies of cough. PMID:22958367

  12. Optimization of a two-stages electrostatic reflex ion source

    Microsoft Academic Search

    A. Farchi; L. Wartski; F. Boukari; V. Roy; Ph. Coste; J. Aubert

    1994-01-01

    In our argon, oxygen, or nitrogen broad beam ion source, 80 mm in diameter, which is either an electrostatic reflex ion source, or a magnetic and electrostatic reflex ion source, the hot filament has been replaced by a carefully optimized microwave plasma (MP) cathode under the electron cyclotron resonance condition. Different geometries of antennae in which the microwave transverse electric

  13. Reflex: Graphical workflow engine for data reduction

    NASA Astrophysics Data System (ADS)

    ESO Reflex development Team

    2014-01-01

    Reflex provides an easy and flexible way to reduce VLT/VLTI science data using the ESO pipelines. It allows graphically specifying the sequence in which the data reduction steps are executed, including conditional stops, loops and conditional branches. It eases inspection of the intermediate and final data products and allows repetition of selected processing steps to optimize the data reduction. The data organization necessary to reduce the data is built into the system and is fully automatic; advanced users can plug their own modules and steps into the data reduction sequence. Reflex supports the development of data reduction workflows based on the ESO Common Pipeline Library. Reflex is based on the concept of a scientific workflow, whereby the data reduction cascade is rendered graphically and data seamlessly flow from one processing step to the next. It is distributed with a number of complete test datasets so users can immediately start experimenting and familiarize themselves with the system.

  14. Trigeminocardiac reflex: current trends.

    PubMed

    Chowdhury, Tumul; Sandu, Nora; Sadr-Eshkevari, Pooyan; Meuwly, Cyrill; Schaller, Bernhard

    2014-01-01

    Since the first introduction of the trigeminocardiac reflex (TCR) in 1999, substantial new knowledge about this brainstem reflex has been created. First, by different clinical case reports and case studies, and second, from basic research that gives inputs from bench to bedside. In the present work, the authors therefore introduce the molecular/anatomical knowledge of the TCR and show its different connections to clinical aspects. Special reference is given to prevention and treatment of the TCR; but always with a link to knowledge of the basis sciences. In such a context different topics of future interest are introduced. PMID:24308808

  15. The role of motivation in the performance of conditioned reflex switching of a maze skill in response to substitution of food reward quality in ants of the species Myrmica rubra.

    PubMed

    Udalova, G P; Karas', A Ya

    2006-11-01

    The characteristics of learning in ants - active Myrmica rubra foragers - were studied in a maze at different levels of colony carbohydrate food need with reinforcement consisting of carbohydrate (sugar syrup) or protein (pupae of Lasius niger ants). Measures of the maze skill during learning reinforced with syrup were somewhat worse than those during learning reinforced with pupae, especially in terms of time-based measures. Ants were able to modify the acquired conditioned reflex reaction when the quality of reinforcement changed. At high levels of food need (" hungry" colony), substitution of syrup with larvae and vice versa was followed by transformation of the previously formed skill; this occurred at both experimental periods (training and testing). At low levels of motivation ("sated colony"), the optimized maze habit formed with protein reinforcement was replaced in the test with carbohydrate reinforcement by a "stochastic," unoptimized behavior with a dominance of investigative activity. These experiments demonstrated that conditioned reflex switching can occur in higher social insects - ants - in which the different forms depend on the level of colony need for food and, respectively, on the level of social food-related motivation of forager ants. The special importance of using the switch activating the corresponding motivational system before changing the reinforcement food quality is emphasized. PMID:17024335

  16. Cockcrow reflex epilepsy

    Microsoft Academic Search

    Agostino Nappo

    1995-01-01

    In epilepsy with reflex seizures, sensory inputs, motor actions or particular forms of mental activity recur as the triggering factors of all or a significant number of the episodes. In the audiogenic variety, complex sounds, musical themes or voices are usually the provocative stimuli although, rarely, animal sounds may be the precipitating perceptions. Symonds [1] records a patient whose seizures

  17. Reflexivity, feminism and difference

    Microsoft Academic Search

    Rahel Wasserfall

    1993-01-01

    This paper addresses the relation of feminist methodology to political commitments. Distinguishing between a “weak” and a “strong” reading of Reflexivity this paper argues that the former contains certain assumptions on the deconstruction of the authority of the author and\\/or of the power difference in field relations. These assumptions are identified and their often problematic nature analyzed. Based on the

  18. Reflexivity in pigeons.

    PubMed

    Sweeney, Mary M; Urcuioli, Peter J

    2010-11-01

    A recent theory of pigeons' equivalence-class formation (Urcuioli, 2008) predicts that reflexivity, an untrained ability to match a stimulus to itself, should be observed after training on two "mirror-image" symbolic successive matching tasks plus identity successive matching using some of the symbolic matching stimuli. One group of pigeons was trained in this fashion; a second group was trained similarly but with successive oddity (rather than identity). Subsequently, comparison-response rates on novel matching versus mismatching sequences with the remaining symbolic matching stimuli were measured on nonreinforced probe trials. Higher rates were observed on matching than on mismatching probes in the former group. The opposite effect--higher rates on mismatching than matching probes--was mostly absent in the latter group, despite being predicted by the theory. Nevertheless, the ostensible reflexivity effect observed in former group may be the first time this phenomenon has been demonstrated in any animal. PMID:21541171

  19. [Deep pudendal reflex].

    PubMed

    Contreras Ortiz, O; Bertotti, A C; Rodríguez Núnez, J D

    1994-01-01

    32 healthy women ranging from 20 to 68 years (51.84 +/- 10.36) were tested for Deep Pudendal Reflex (DPR). Dantec 13L40 (St. Mark's) superficial electrodes were used to pick up the responses of the external anal sphincter. These devices consist of a bipolar stimulating electrode mounted on the tip of the gloved index finger which is inserted into the rectum; 3 cm proximally at the base of the finger are recording electrodes which pick up the contraction response of the anal sphincter. To obtain the DPR the ischial spine is localized on transrectal examination and electrical stimuli given at that side, applying square stimulus of 0.2 ms duration and 0.5 Hz frequency. This stimulates the pudendal nerve as it leaves the pelvis through the greater sciatic notch, before it branches into the inferior rectal (to the anal sphincter) and perineal nerve (to the periurethral striated muscle). The conduction time was measured as the latency from the time of stimulation of the starting point of the reflex response curves. The shortest latency of various responses was accepted and measured in milliseconds (ms). The amplitudes of the responses were measured in microvolts (uv). We obtained reproducible DPR in all subjects. Mean latency was 36.18 +/- 4.29 ms; mean amplitude was 337.50 +/- 218.49 uv (Fig. 1, Table 2). DPR is a pudendal-anal reflex like the bulbo-cavernous reflex, but differs in latency, stimulation localization and afferent limb although both follow a common final afferent pathway. PMID:7658974

  20. Adductor T reflex abnormalities in patients with decreased patellar reflexes.

    PubMed

    Tataroglu, Cengiz; Deneri, Ersin; Ozkul, Ayca; Sair, Ahmet; Yaycioglu, Soner

    2009-08-01

    The adductor reflex (AR) is a tendon reflex that has various features that differ from other tendon reflexes. This reflex was tested in different disorders presenting with diminished patellar reflexes such as diabetic lumbosacral radiculoplexus neuropathy (DLRPN), L2-L4 radiculopathy, and distal symmetric diabetic neuropathy (diabetic PNP). The AR and crossed-AR (elicited by tapping the contralateral patellar tendon) were recorded using concentric needle electrodes. Additionally, the patellar T reflex (vm-TR) and vastus medialis H reflex (vm-HR) were recorded using surface electrodes. AR was recorded in only one out of eight patients with DLRPN, but it was recorded in 21 out of 22 patients with L2-L4 radiculopathy (95.5%). Of these reflexes, only AR showed prolonged latency in the L2-L4 radiculopathy group. The latencies of AR, vm-TR, and vm-HR were prolonged in patients with diabetic PNP. We conclude that AR can be useful in the differential diagnosis of some lower motor neuron disorders that present with patellar reflex disturbance. Muscle Nerve 40: 264-270, 2009. PMID:19609916

  1. Procrustes problems for (P,Q,[eta])-reflexive matrices

    NASA Astrophysics Data System (ADS)

    Jia, Zhigang; Wang, Qian; Wei, Musheng

    2010-04-01

    This paper characterizes (P,Q,[eta])-reflexive matrices, showing that a (P,Q,[eta])-reflexive matrix can be represented in terms of k matrices , where , ma and nb are dimensions of the [tau]a- and [tau]b-eigenspaces of P and Q, respectively. A general solution of Procrustes problems of (P,Q,[eta])-reflexive matrices is presented in terms of lower-order matrices A1,[eta]-1,...,A[eta]-1,1,A[eta],k,A[eta]+1,k-1,...,Ak,[eta] under the condition that P and Q are unitary.

  2. Reflexive Accounts and Accounts of Reflexivity in Qualitative Data Analysis

    Microsoft Academic Search

    Natasha S. Mauthner; Andrea Doucet

    2003-01-01

    While the importance of being reflexive is acknowledged within social science research, the difficulties, practicalities and methods of doing it are rarely addressed. Thus, the implications of current theoretical and philosophical discussions about reflexivity, epistemology and the construction of knowledge for empirical socio- logical research practice, specifically the analysis of qualitative data, remain under- developed. Drawing on our doctoral experiences,

  3. REFLEX DEPRESSION IN R HYTHMICALLY ACTIVE MONOSYNAPTIC REFLEX PATHWAYS

    Microsoft Academic Search

    DAVID P. C. LLOYD; VICTOR J. WILSON

    2010-01-01

    Fluctuation of excitability in the spinal cord in one sense has been a source of annoyance to most who have employed monosynaptic reflexes for one pur- pose or another. At an early stage in the exploitation of monosynaptic reflexes it became usual practice to record a number of responses in any given cir- cumstance and to average the lot in

  4. Baroreceptor Reflex Role Play

    NSDL National Science Digital Library

    Marlene Y. MacLeish

    2012-06-26

    In this activity about the baroreceptor reflex (BR) arc (page 123 of the PDF), learners discover the importance of maintaining adequate arterial blood pressure through a role playing exercise. This activity will model how the brain processes information and sends out signals to the heart and arteries. Learners can also consider how this affects astronauts in the microgravity environment of space. The lesson guide, part of NASA's "The Brain in Space: A Teacher's Guide with Activities for Neuroscience," includes background information and evaluation strategies. Note: this activity requires 9 learners per group.

  5. An experimental psychophysiological approach to human bradycardiac reflexes.

    PubMed

    Furedy, J J

    1985-01-01

    Bradycardic reflexes in man are both of scientific and clinical interest. Using the methods of experimental psychophysiology, control over relevant independent variables permits the study of fine-grained temporal physiologic response topographies, and of psychological factors that may modify the reflex. In addition, information can also be sought through interdisciplinary collaborations with experimental physiologists in order to shed light on the mechanism of the reflexes. These general features of the approach are illustrated by presenting data on two bradycardic reflex preparations: the laboratory dive analog, and the 90-degree negative tilt. The dive-analog studies have shown that a) the dive-reflex proper is a late-occurring bradycardia accompanied by a late-occurring vasoconstriction; and b) for the elicitation of this reflex, both breath-holding and face immersion are necessary. In addition, the physiologic manipulation of temperature affects the reflex in an inverse way over the range of 10 degrees to 40 degrees C, while the sense of control (a psychological variable) attenuates the reflex. The negative-tilt preparation produces a bradycardic response that is ideal as a Pavlovian unconditional response. Some Pavlovian conditioning arrangements, especially an "imaginational" form, do produce significant conditional bradycardic responding, and this has both potential clinical (e.g., biofeedback-related) and theoretical (e.g., S-R vs. S-S accounts of Pavlovian conditioning) applications. The paper ends with a comment on the cognitive paradigm shift in psychology. Although this shift is of importance, it is suggested that it is also important to "remember the response." PMID:4000733

  6. The Relationship between MOC Reflex and Masked Threshold

    PubMed Central

    Garinis, Angela; Werner, Lynne; Abdala, Carolina

    2011-01-01

    Otoacoustic emission (OAE) amplitude can be reduced by acoustic stimulation. This effect is produced by the medial olivocochlear (MOC) reflex. Past studies have shown that the MOC reflex is related to listening in noise and attention. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold was investigated in 19 adults. Detection thresholds were determined for a 1000-Hz, 300-ms tone presented simultaneously with one repetition of a 300-ms masker in an ongoing train of 300-ms masker bursts at 600-ms intervals. Three masking conditions were tested: 1) broadband noise 2) a fixed-frequency 4-tone complex masker and 3) a random-frequency 4-tone complex masker. Broadband noise was expected to produce energetic masking and the tonal maskers were expected to produce informational masking in some listeners. DPOAEs were recorded at fine frequency interval from 500 to 4000 Hz, with and without contralateral acoustic stimulation. MOC reflex strength was estimated as a reduction in baseline level and a shift in frequency of DPOAE fine-structure maxima near 1000-Hz. MOC reflex and psychophysical testing were completed in separate sessions. Individuals with poorer thresholds in broadband noise and in random-frequency maskers were found to have stronger MOC reflexes. PMID:21878379

  7. Reflexive Planning for Later Life

    Microsoft Academic Search

    Margaret A. Denton; Candace L. Kemp; Susan French; Amiram Gafni; Anju Joshi; Carolyn J. Rosenthal; Sharon Davies

    2004-01-01

    Informed by Giddens’ (1991) concept of reflexive life planning and the notion of later life as a time of increasing social and financial risk, this research explores the idea of reflexive planning for later life. We utilize a conceptual model that incorporates three types of planning for later life: public protection, self-insurance, and self-protection. Drawing on qualitative, life-history data from

  8. Vestibulo-spinal reflex mechanisms

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.

    1981-01-01

    The specific objectives of experiments designed to investigate postural reflex behavior during sustained weightlessness are discussed. The first is to investigate, during prolonged weightlessness with Hoffmann response (H-reflex) measurement procedures, vestibulo-spinal reflexes associated with vestibular (otolith) responses evoked during an applied linear acceleration. This objective includes not only an evaluation of otolith-induced changes in a major postural muscle but also an investigation with this technique of the adaptive process of the vestibular system and spinal reflex mechanisms to this unique environment. The second objective is to relate space motion sickness to the results of this investigation. Finally, a return to the vestibulo-spinal and postural reflexes to normal values following the flight will be examined. The flight experiment involves activation of nerve tissue (tibial N) with electrical shock and the recording of resulting muscle activity (soleus) with surface electrodes. Soleus/spinal H-reflex testing procedures will be used in conjuction with linear acceleration through the subject's X-axis.

  9. Simultaneous characterizations of reflex and nonreflex dynamic and static changes in spastic hemiparesis

    PubMed Central

    Chung, Sun G.; Ren, Yupeng; Liu, Lin; Roth, Elliot J.; Rymer, W. Zev

    2013-01-01

    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 < 0.038) and was not regulated with muscle contraction, indicating impaired tonic stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction (P < 0.012) than controls (P < 0.023) and higher in dorsi-flexors at lower torques (P < 0.038), primarily because of its increase at rest (P = 0.045), indicating exaggerated phasic 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. PMID:23636726

  10. Sensitivity of the jaw-jerk reflex in patients with myogenous temporomandibular disorder.

    PubMed

    Lobbezoo, F; van der Glas, H W; van der Bilt, A; Buchner, R; Bosman, F

    1996-06-01

    Changes in the activity of human jaw-elevator muscles related to the mandibular stretch (jaw-jerk) reflex could be involved in the aetiology of temporomandibular disorders (TMD). In order to investigate whether there are differences in the sensitivity of the jaw-jerk reflex between myogenous TMD patients (n = 10) and gender- and age-matched controls (n = 10), jaw-jerk reflexes were elicited under standardized conditions. By measuring the reflex with bipolar surface electromyography (EMG), reflex sensitivity was determined from relations between reflex amplitude and jaw displacement from the masseter and the anterior temporalis muscles. Reflex amplitude and background EMG activity were normalized with respect to the maximal voluntary contraction (MVC) to correct for differences in the thickness of soft tissues overlying the muscle or in electrode placement. In addition to normalization with respect to MVC, for the patients, normalization was also applied with respect to a MVC that was scaled by multiplying values by the ratio of the mean MVC of controls to the mean MVC of patients. At a constant level of background EMG activity, the reflex sensitivity can be determined from the slope (reflex gain) and x-intercept (reflex threshold) of the reflex amplitude-jaw displacement relation. No significant differences between patients and controls were found for the gain or threshold values of either the masseter or the anterior temporalis muscles with a univariate analysis of variance. It is concluded that jaw-jerk reflex sensitivity is not significantly changed in myogenous TMD patients. Therefore, the fusimotor system probably does not play a part in the perpetuating myogenous TMD. PMID:8937646

  11. Reflex seizures in Rett syndrome.

    PubMed

    Roche Martínez, Ana; Alonso Colmenero, M Itziar; Gomes Pereira, Andreia; Sanmartí Vilaplana, Francesc X; Armstrong Morón, Judith; Pineda Marfa, Mercé

    2011-12-01

    Reflex seizures are a rare phenomenon among epileptic patients, in which an epileptic discharge is triggered by various kinds of stimuli (visual, auditory, tactile or gustatory). Epilepsy is common in Rett syndrome patients (up to 70%), but to the authors' knowledge, no pressure or eating-triggered seizures have yet been reported in Rett children. We describe three epileptic Rett patients with reflex seizures, triggered by food intake or proprioception. One patient with congenital Rett Sd. developed infantile epileptic spasms at around seven months and two patients with classic Rett Sd. presented with generalised tonic-clonic seizures at around five years. Reflex seizures appeared when the patients were teenagers. The congenital-Rett patient presented eating-triggered seizures at the beginning of almost every meal, demonstrated by EEG recording. Both classic Rett patients showed self-provoked pressure -triggered attacks, influenced by stress or excitement. Non-triggered seizures were controlled with carbamazepine or valproate, but reflex seizures did not respond to antiepileptic drugs. Risperidone partially improved self-provoked seizures. When reflex seizures are suspected, reproducing the trigger during EEG recording is fundamental; however, self-provoked seizures depend largely on the patient's will. Optimal therapy (though not always possible) consists of avoiding the trigger. Stress modifiers such as risperidone may help control self-provoked seizures. PMID:22258043

  12. Avian reflex and electroencephalogram responses in different states of consciousness.

    PubMed

    Sandercock, Dale A; Auckburally, Adam; Flaherty, Derek; Sandilands, Victoria; McKeegan, Dorothy E F

    2014-06-22

    Defining states of clinical consciousness in animals is important in veterinary anaesthesia and in studies of euthanasia and welfare assessment at slaughter. The aim of this study was to validate readily observable reflex responses in relation to different conscious states, as confirmed by EEG analysis, in two species of birds under laboratory conditions (35-week-old layer hens (n=12) and 11-week-old turkeys (n=10)). We evaluated clinical reflexes and characterised electroencephalograph (EEG) activity (as a measure of brain function) using spectral analyses in four different clinical states of consciousness: conscious (fully awake), semi-conscious (sedated), unconscious-optimal (general anaesthesia), unconscious-sub optimal (deep hypnotic state), as well as assessment immediately following euthanasia. Jaw or neck muscle tone was the most reliable reflex measure distinguishing between conscious and unconscious states. Pupillary reflex was consistently observed until respiratory arrest. Nictitating membrane reflex persisted for a short time (<1 min) after respiratory arrest and brain death (isoelectric EEG). The results confirm that the nictitating membrane reflex is a conservative measure of death in poultry. Using spectral analyses of the EEG waveforms it was possible to readily distinguish between the different states of clinical consciousness. In all cases, when birds progressed from a conscious to unconscious state; total spectral power (PTOT) significantly increased, whereas median (F50) and spectral edge (F95) frequencies significantly decreased. This study demonstrates that EEG analysis can differentiate between clinical states (and loss of brain function at death) in birds and provides a unique integration of reflex responses and EEG activity. PMID:24878315

  13. Enhanced stretch reflex excitability in the soleus muscle during passive standing posture in humans.

    PubMed

    Shimba, Sachio; Kawashima, Noritaka; Ohta, Yuji; Yamamoto, Shin-ichiroh; Nakazawa, Kimitaka

    2010-06-01

    The purpose of this study was to test whether the spinal reflex excitability of the soleus muscle is modulated as posture changes from a supine to a passive upright position. Eight healthy subjects (29.6+/-5.4 yrs) participated in this study. Stretch and H-reflex responses were elicited while the subjects maintained passive standing (ST) and supine (SP) postures. The passive standing posture was accomplished by using a gait orthosis to which a custom-made device was mounted to elicit stretch reflex in the soleus muscle. This orthosis makes it possible to elicit stretch and H-reflexes without background muscle activity in the soleus muscle. The results revealed that the H-reflex amplitude in the ST was smaller than that in the SP condition, which is in good agreement with previous reports. On the other hand, the stretch reflex was significantly larger in the ST than in the SP condition. Since the experimental conditions of both the stretch and H-reflex measurements were exactly the same, the results were attributed to differences in the underlying neural mechanisms of the two reflex systems: different sensitivity of the presynaptic inhibition onto the spinal motoneuron pool and/or a change in the muscle spindle sensitivity. PMID:19427232

  14. Axially evoked postural reflexes: influence of task.

    PubMed

    Govender, Sendhil; Dennis, Danielle L; Colebatch, James G

    2015-01-01

    Postural reflexes were recorded in healthy subjects (n = 17) using brief axial accelerations and tap stimuli applied at the vertebra prominens (C7) and manubrium sterni. Short latency (SL) responses were recorded from the soleus, hamstrings and tibialis anterior muscles and expressed as a percentage of the background EMG prior to stimulus onset. In the majority of postural conditions tested, subjects were recorded standing erect and leaning forward with their feet together. The SL response was larger for soleus than for the hamstrings during standing (soleus vs hamstrings; 70.4 vs 28.1%), whereas the opposite occurred during kneeling (25.3 vs 127.3%). Concordant head and trunk accelerations produced larger SL responses than discordant accelerations for soleus and hamstrings, but the evoked excitatory response was independent of head direction and as expected for the direction of truncal acceleration. Postural reflexes for soleus and tibialis anterior were strongly affected by conditions that posed a significant threat to postural stability; stimulation at C7 was associated with significant SL enhancement for soleus during anterior lean while sternal stimulation showed SL enhancement for tibialis anterior during posterior lean. Cutaneous anaesthesia applied over the C7 stimulation site had no significant effect on EMG responses, nor did vision or surface type (rigid or compliant). This study provides further evidence that postural reflexes produced by brief axial accelerations are independent of cutaneous receptors, vestibular afferents and ankle proprioceptors, and demonstrates that postural tasks and truncal orientation significantly affect the evoked response, consistent with a role in stabilising posture. PMID:25300958

  15. Effect of cervicolabyrinthine impulsation on the spinal reflex apparatus

    NASA Technical Reports Server (NTRS)

    Yarotskiy, A. I.

    1980-01-01

    In view of the fact that the convergence effect of vestibular impulsation may both stimulate and inhibit intra and intersystemic coordination of physiological processes, an attempt was made to define the physiological effect on the spinal reflex apparatus of the convergence of cervicolabyrinthine impulsation on a model of the unconditioned motor reflex as a mechanism of the common final pathway conditioning the formation and realization of a focused beneficial result of human motor activities. More than 100 persons subjected to rolling effect and angular acceleration during complexly coordinated muscular loading were divided according to typical variants of the functional structure of the patella reflex in an experiment requiring 30 rapid counterclockwise head revolutions at 2/sec with synchronous recording of a 20 item series of patella reflex acts. A knee jerk coefficient was used in calculations. In 85 percent of the cases 2 patellar reflexograms show typical braking and release of knee reflex and 1 shows an extreme local variant. The diagnostic and prognostic value of these tests is suggested for determining adaptive possibilities of functional systems in respect to acceleration and proprioceptive stimuli.

  16. Neurophysiology and Clinical Implications of the Laryngeal Adductor Reflex

    PubMed Central

    Domer, Amanda S.; Kuhn, Maggie A.

    2014-01-01

    The laryngeal adductor reflex (LAR) is an involuntary protective response to stimuli in the larynx. The superior laryngeal nerve (SLN) acts as the afferent limb and the recurrent laryngeal nerve (RLN) as the efferent limb of this reflex, which is modulated by the central nervous system. Perhaps the most clinically significant application of the LAR is its use in laryngopharyngeal (LP) sensory discrimination testing. Importantly, aberrations in the LAR may predict dysphagia or portend clinical phenotypes of chronic cough, vocal cord dysfunction or pediatric apneas. LP sensation is a potential target for interventions addressing the aforementioned conditions though currently remains an area of active investigation. PMID:25254155

  17. REFLEXIVE DIGRAPHS WITH NEAR UNANIMITY POLYMORPHISMS

    E-print Network

    Maróti, Miklós

    REFLEXIVE DIGRAPHS WITH NEAR UNANIMITY POLYMORPHISMS M. MAR´OTI AND L. Z´ADORI In Celebration of the Seventieth Birthday of Ralph McKenzie Abstract. In this paper we prove that if a finite reflexive digraph of similar results obtained earlier for posets and symmetric reflexive digraphs by the second author and his

  18. Hand muscle reflexes following air puff stimulation

    Microsoft Academic Search

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

    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

  19. Adaptation of reflexive feedback during arm posture to different environments.

    PubMed

    de Vlugt, Erwin; Schouten, Alfred C; van der Helm, Frans C T

    2002-07-01

    In this study we have examined the ability of the central nervous system (CNS) to use spinal reflexes to minimize displacements during postural control while continuous force perturbations were applied at the hand. The subjects were instructed to minimize the displacements of the hand from a reference position that resulted from the force perturbations. The perturbations were imposed in one direction by means of a hydraulic manipulator of which the virtual mass and damping were varied. Resistance to the perturbations came from intrinsic and reflexive stiffness, and from the virtual environment. It is hypothesized that reflexive feedback during posture maintenance is optimally adjusted such that position deviations are minimal for a given virtual environment. Frequency response functions were estimated, capturing all mechanical properties of the arm at the end point (hand) level. Intrinsic and reflexive parameters were quantified by fitting a linear neuromuscular model to the frequency responses. The reflexive length feedback gain increased strongly with damping and little with the eigenfrequency of the total combined system (i.e. arm plus environment). The reflexive velocity feedback gain decreased slightly with relative damping at the largest eigenfrequency and more markedly at smaller eigenfrequencies. In the case of highest reflex gains, the total system remained stable and sufficiently damped while the responses of only the arm were severely underdamped and sometimes even unstable. To further analyse these results, a model optimization was performed. Intrinsic and reflexive parameters were optimized such that two criterion functions were minimized. The first concerns performance and penalized hand displacements from a reference point. The second one weights afferent control effort to avoid inefficient feedback. The simulations showed good similarities with the estimated values. Length feedback was adequately predicted by the model for all conditions. The predicted velocity feedback gains were larger in all cases, probably indicating a mutual gain limiting relation between length and velocity afferent signals. The results suggest that both reflex gains seem to be adjusted by the CNS, where in particular the length feedback gain was optimal so as to maximize performance at minimum control effort. PMID:12111265

  20. List Homomorphisms to reflexive digraphs

    E-print Network

    Tomás Feder; Pavol Hell; Jing Huang; Arash Rafiey

    We study list homomorphism problems L-HOM(H) for the class of reflexive digraphs H (digraphs in which each vertex has a loop). These problems have been intensively studied in the case of undirected graphs H, and appear to be more difficult for digraphs. However, it is known that each problem L

  1. Vestibular-ocular accommodation reflex in man

    NASA Technical Reports Server (NTRS)

    Clark, B.; Randle, R. J.; Stewart, J. D.

    1975-01-01

    Stimulation of the vestibular system by angular acceleration produces widespread sensory and motor effects. The present paper studies a motor effect which has not been reported in the literature, i.e., the influence of rotary acceleration of the body on ocular accommodation. The accommodation of 10 young men was recorded before and after a high-level deceleration to zero velocity following 30 sec of rotating. Accommodation was recorded continuously on an infrared optometer for 110 sec under two conditions: while the subjects observed a target set at the far point, and while they viewed the same target through a 0.3-mm pinhole. Stimulation by high-level rotary deceleration produced positive accommodation or a pseudomyopia under both conditions, but the positive accommodation was substantially greater and lasted much longer during fixation through the pinhole. It is hypothesized that this increase in accommodation is a result of a vestibular-ocular accommodation reflex.

  2. Trigeminocardiac reflexes: maxillary and mandibular variants of the oculocardiac reflex.

    PubMed

    Lang, S; Lanigan, D T; van der Wal, M

    1991-09-01

    Three case reports are presented to illustrate the existence and importance of reflex bradycardic responses that can occur during maxillofacial surgical procedures. All three patients were healthy young adults undergoing operations which did not include any manipulation of orbital structures. After the patients had been anaesthetized for some time and were haemodynamically stable, profound bradycardia or ventricular asystole occurred suddenly in response to manipulations of the bony structures of the maxilla or mandible, or dissection of, or traction on, the attached soft tissue structures. The parasympathetic supply to the face is carried in the trigeminal nerve. Alternative afferent pathways must exist via the maxillary and/or mandibular divisions, in addition to the commonly reported pathway via the ophthalmic division of the trigeminal nerve in the classic oculocardiac reflex. The efferent arc involves the vagus, regardless of which branch of the trigeminal nerve transmits the afferent impulses. All patients undergoing maxillofacial procedures should be monitored carefully for reflex bradycardia and ventricular asystole. PMID:1914059

  3. Vestibular reflexes of otolith origin

    NASA Technical Reports Server (NTRS)

    Wilson, Victor J.

    1988-01-01

    The vestibular system and its role in the maintenance of posture and in motion sickness is investigated using cats as experimental subjects. The assumption is that better understanding of the physiology of vestibular pathways is not only of intrinsic value, but will help to explain and eventually alleviate the disturbances caused by vestibular malfunction, or by exposure to an unusual environment such as space. The first project deals with the influence on the spinal cord of stimulation of the vestibular labyrinth, particularly the otoliths. A second was concerned with the properties and neural basis of the tonic neck reflex. These two projects are related, because vestibulospinal and tonic neck reflexes interact in the maintenance of normal posture. The third project began with an interest in mechanisms of motion sickness, and eventually shifted to a study of central control of respiratory muscles involved in vomiting.

  4. Human stretch reflex pathways reexamined

    PubMed Central

    Yavuz, ?. Utku; Mrachacz-Kersting, Natalie; Sebik, O?uz; Berna Ünver, M.; Farina, Dario

    2013-01-01

    Reflex responses of tibialis anterior motor units to stretch stimuli were investigated in human subjects. Three types of stretch stimuli were applied (tap-like, ramp-and-hold, and half-sine stretch). Stimulus-induced responses in single motor units were analyzed using the classical technique, which involved building average surface electromyogram (SEMG) and peristimulus time histograms (PSTH) from the discharge times of motor units and peristimulus frequencygrams (PSF) from the instantaneous discharge rates of single motor units. With the use of SEMG and PSTH, the tap-like stretch stimulus induced five separate reflex responses, on average. With the same single motor unit data, the PSF technique indicated that the tap stimulus induced only three reflex responses. Similar to the finding using the tap-like stretch stimuli, ramp-and-hold stimuli induced several peaks and troughs in the SEMG and PSTH. The PSF analyses displayed genuine increases in discharge rates underlying the peaks but not underlying the troughs. Half-sine stretch stimuli induced a long-lasting excitation followed by a long-lasting silent period in SEMG and PSTH. The increase in the discharge rate, however, lasted for the entire duration of the stimulus and continued during the silent period. The results are discussed in the light of the fact that the discharge rate of a motoneuron has a strong positive linear association with the effective synaptic current it receives and hence represents changes in the membrane potential more directly and accurately than the other indirect measures. This study suggests that the neuronal pathway of the human stretch reflex does not include inhibitory pathways. PMID:24225537

  5. Modulation of physiological reflexes by pain: role of the locus coeruleus

    PubMed Central

    Szabadi, Elemer

    2012-01-01

    The locus coeruleus (LC) is activated by noxious stimuli, and this activation leads to inhibition of perceived pain. As two physiological reflexes, the acoustic startle reflex and the pupillary light reflex, are sensitive to noxious stimuli, this review considers evidence that this sensitivity, at least to some extent, is mediated by the LC. The acoustic startle reflex, contraction of a large body of skeletal muscles in response to a sudden loud acoustic stimulus, can be enhanced by both directly (“sensitization”) and indirectly (“fear conditioning”) applied noxious stimuli. Fear-conditioning involves the association of a noxious (unconditioned) stimulus with a neutral (conditioned) stimulus (e.g., light), leading to the ability of the conditioned stimulus to evoke the “pain response”. The enhancement of the startle response by conditioned fear (“fear-potentiated startle”) involves the activation of the amygdala. The LC may also be involved in both sensitization and fear potentiation: pain signals activate the LC both directly and indirectly via the amygdala, which results in enhanced motoneurone activity, leading to an enhanced muscular response. Pupil diameter is under dual sympathetic/parasympathetic control, the sympathetic (noradrenergic) output dilating, and the parasympathetic (cholinergic) output constricting the pupil. The light reflex (constriction of the pupil in response to a light stimulus) operates via the parasympathetic output. The LC exerts a dual influence on pupillary control: it contributes to the sympathetic outflow and attenuates the parasympathetic output by inhibiting the Edinger-Westphal nucleus, the preganglionic cholinergic nucleus in the light reflex pathway. Noxious stimulation results in pupil dilation (“reflex dilation”), without any change in the light reflex response, consistent with sympathetic activation via the LC. Conditioned fear, on the other hand, results in the attenuation of the light reflex response (“fear-inhibited light reflex”), consistent with the inhibition of the parasympathetic light reflex via the LC. It is suggested that directly applied pain and fear-conditioning may affect different populations of autonomic neurones in the LC, directly applied pain activating sympathetic and fear-conditioning parasympathetic premotor neurones. PMID:23087627

  6. Trigeminocardiac reflex in the Postanesthesia care unit.

    PubMed

    Hemmer, Laura B; Afifi, Sherif; Koht, Antoun

    2010-05-01

    Bradycardia caused by the oculocardiac reflex is an anticipated occurrence during certain surgeries. The afferent pathway involves the trigeminal nerve's ophthalmic division. Reflex bradycardia from the trigeminocardiac reflex, via stimulation of maxillary or mandibular divisions of cranial nerve V, although less well known, has also been reported intraoperatively. Unstable bradycardia associated with stimulation of the mandibular division of cranial nerve V during trigeminal neuralgia pain episodes in the Postanesthesia Care Unit is presented. PMID:20400008

  7. The oculocardiag reflex during strabismus surgery

    Microsoft Academic Search

    George T Moonie; Donald L Rees; Denzil Elton

    1964-01-01

    Conclusions  The oculocardiac reflex was noted m 44 of 66 patients undergoing strabismus surgery Disturbances occurred at the time of extraocular\\u000a muscle traction in the absence of hypercarbia and hypoxia The oculocardiac reflex proved to be much more active than the vago-vagal\\u000a reflex associated with intubation Arrhythmias were not produced during intubation of a group of 9 patients, but later 6

  8. Study of the early somatosympathetic reflex response.

    PubMed

    Lebedev, V P; Rosanov, N N; Skobelev, V A; Smirnov, K A

    1976-08-01

    Using anesthetized cats, we studied the early components of the somatosympathetic reflex in the white rami communicantes of segments T(3) and L(2) in response to stimulation of the corresponding segmental somatic nerves. The results show that the early somatosympathetic reflex is a complex and highly organized response consisting of three typical waves. The shortest latency wave of this reflex was investigated in detail and evidence of its monosynaptic nature was obtained. Calculations showed that the efferent part of this reflex component may be formed by sympathetic preganglionic neurons with axonal conduction velocities of about 10 m/sec or more. PMID:19604852

  9. Modulation of trigeminal reflex excitability in migraine: effects of attention and habituation on the blink reflex.

    PubMed

    de Tommaso, Marina; Murasecco, Donatella; Libro, Giuseppe; Guido, Marco; Sciruicchio, Vittorio; Specchio, Luigi Maria; Gallai, Virgilio; Puca, Francomichele

    2002-06-01

    The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex- and age-matched controls were selected. In subgroups of migraine with-aura and without-aura patients, and normal controls, the blink reflex was elicited during different cognitive situations: (a) spontaneous mental activity; (b) stimulus anticipation; (c) recognition of target numbers. In the remaining subjects, R2 and R3 habituation was evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s intervals. The R2 and R3 recovery curves were also computed. A reduced R3 threshold with a normal pain threshold was found in migraine with-aura and without-aura patients; the R3 component was not significantly correlated with the pain thresholds in patients and controls. The R2 and R3 components were less influenced by the warning of the stimulus in migraine without-aura and migraine with-aura patients, in comparison with the control group. A slight increase of both R2 and R3 recovery after preconditioning stimulus was also observed in migraine patients, probably caused by a phenomenon of trigeminal hyperexcitability persisting after the last attack. The abnormal BR modulation by alerting expresses in migraine a dysfunction of adaptation capacity to environmental conditions, probably predisposing to migraine. PMID:12031298

  10. The Dynamics of the Stapedial Acoustic Reflex.

    NASA Astrophysics Data System (ADS)

    Moss, Sherrin Mary

    Available from UMI in association with The British Library. This thesis aims to separate the neural and muscular components of the stapedial acoustic reflex, both anatomically and physiologically. It aims to present an hypothesis to account for the differences between ipsilateral and contralateral reflex characteristics which have so far been unexplained, and achieve a greater understanding of the mechanisms underlying the reflex dynamics. A technique enabling faithful reproduction of the time course of the reflex is used throughout the experimental work. The technique measures tympanic membrane displacement as a result of reflex stapedius muscle contraction. The recorded response can be directly related to the mechanics of the middle ear and stapedius muscle contraction. Some development of the technique is undertaken by the author. A model of the reflex neural arc and stapedius muscle dynamics is evolved that is based upon a second order system. The model is unique in that it includes a latency in the ipsilateral negative feedback loop. Oscillations commonly observed on reflex responses are seen to be produced because of the inclusion of a latency in the feedback loop. The model demonstrates and explains the complex relationships between neural and muscle dynamic parameters observed in the experimental work. This more comprehensive understanding of the interaction between the stapedius dynamics and the neural arc of the reflex would not usually have been possible using human subjects, coupled with a non-invasive measurement technique. Evidence from the experimental work revealed the ipsilateral reflex to have, on average, a 5 dB lower threshold than the contralateral reflex. The oscillatory charcteristics, and the steady state response, of the contralateral reflex are also seen to be significantly different from those of the ipsilateral reflex. An hypothesis to account for the experimental observations is proposed. It is propounded that chemical neurotransmitters, and their effect upon the contralateral reflex arc from the site of the superior olivary complex to the motoneurones innervating the stapedius, account for the difference between the contralateral and ipsilateral reflex thresholds and dynamic characteristics. In the past two years the measurement technique used for the experimental work has developed from an audiological to a neurological diagnostic tool. This has enabled the results from the study to be applied in the field for valuable biomechanical and neurological explanations of the reflex response. (Abstract shortened by UMI.).

  11. Partial restoration of blink reflex function after spinal accessory-facial nerve anastomosis.

    PubMed Central

    Danziger, N; Chassande, B; Lamas, G; Fligny, I; Soudant, J; Willer, J C

    1995-01-01

    Functional motor control requires perfect matching of the central connections of motoneurons with their peripheral inputs. It is not known, however, to what extent these central circuits are influenced by target muscles, either during development or after a lesion. Surgical interventions aimed at restoring function after peripheral nerve lesions provide an opportunity for studying this interaction in the mature human nervous system. A patient was studied in whom the spinal accessory nerve was anastomosed into a lesioned facial nerve, allowing voluntary contractions of the previously paralysed muscles. This procedure, in addition to replacing the facial neurons at peripheral synapses, allowed a new short latency trigeminospinal accessory reflex of the R1 blink reflex type to be demonstrated, implying that trigeminal neurons had sprouted towards spinal accessory motoneurons over a distance of at least 1 cm. These results show an unexpected influence of the periphery in remodelling central connectivity in humans. The motoneuronal excitability for this R1 reflex response was therefore studied to compare the convergent properties of facial motoneurons (normal side) with those of the spinal accessory motoneurons (operated side) using a classic double shock technique with variable interstimulus intervals (conditioning test stimulus). On the normal side, conditioning stimuli (to the ipsilateral or contralateral infraliminar supraorbital nerve) produced a clearcut facilitation of the R1 blink reflex when the interstimulus interval was 30-80 ms. By contrast, a similar procedure had no effect on the R1 blink reflex mediated via the trigeminal-spinal accessory reflex arc. These data indicate that despite the heterotopic sprouting of some axons from neurons in the XIth nucleus, motoneurons involved in the newly formed reflex arc remain totally inexcitable by other trigeminal afferents and seem unable to ensure a physiological functioning of the normal blink reflex. Thus the functional relevance of the recovered R1 blink response remains unclear. PMID:7876856

  12. Studies of the horizontal vestibulo-ocular reflex in spaceflight

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Tom; Pool, Sam

    1989-01-01

    Changes in the vestibulo-ocular reflex (VOR) during space flight have been suspected of contributing to space motion sickness. The horizontal VOR was studied in nine subjects on two space shuttle missions. Active unpaced head oscillation at 0.3 Hz was used as the stimulus to examine the gain and phase of the VOR with and without visual input, as well as the visual suppression of the reflex. No statistically significant changes were noted inflight in the gains or phase shifts of the VOR during any test condition, or between space motion sickness susceptible and nonsusceptible populations. Although VOR suppression was unaffected by spaceflight, the space motion sickness-susceptible group tended to exhibit greater error in the suppression than the nonsusceptible group. It is concluded that at this stimulus frequency, VOR gain is unaffected by space-flight, and any minor individual changes do not seem to contribute to space motion sickness.

  13. Abnormal oculocardiac reflex in two patients with Marcus Gunn syndrome.

    PubMed

    Pandey, Maitree; Baduni, Neha; Jain, Aruna; Sanwal, Manoj Kumar; Vajifdar, Homay

    2011-07-01

    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. PMID:21897519

  14. Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

    ERIC Educational Resources Information Center

    Cohen, Marlene R.; Meissner, Geoffrey W.; Schafer, Robert J.; Raymond, Jennifer L.

    2004-01-01

    Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the…

  15. Achilles tendon reflex measuring system

    NASA Astrophysics Data System (ADS)

    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.

  16. Modulation of the soleus H-reflex during knee rotations is not consistent with muscle fascicle length changes.

    PubMed

    Tokuno, Craig D; Lichtwark, Glen A; Cresswell, Andrew G

    2012-09-01

    The purpose of this study was to examine whether passively rotating the knee would result in parallel or differential changes to the medial gastrocnemius (MG) and soleus (SOL) H-reflex amplitudes. Since passive knee rotation alters the muscle length of the MG, but not the SOL, it was hypothesized that the MG H-reflex would reflect the lengthening or shortening actions that occur during knee rotation, whereas the SOL H-reflex would remain unaltered. MG and SOL Hoffman reflexes (H-reflexes) were evoked with the knee joint held static at 10° or as the joint was passively flexed or extended past 10°. Ultrasound recordings were used to confirm whether the knee rotations altered MG but not SOL muscle fascicle lengths. In contrast to our hypothesis, results indicated that the MG and SOL H-reflexes were similarly affected during knee rotations, with both MG and SOL H(max):M(max) smaller during the knee extension than the knee flexion (33-43% reduction) and static (22-28% reduction) conditions. Parallel changes to the MG and SOL H-reflexes occurred despite a differential effect of knee rotation on muscle fascicle lengths. Whereas, MG muscle fascicles lengthened and shortened during knee extension and flexion, respectively, SOL fascicles length remained unchanged. Given the strong neural coupling between the MG and SOL motoneuron pools, the results highlight the difficulty in isolating specific variables (e.g., muscle length) when determining the modulatory influences on the triceps surae H-reflex amplitude. PMID:22234398

  17. Reflex responses of masseter muscles to sound.

    PubMed

    Deriu, Franca; Giaconi, Elena; Rothwell, John C; Tolu, Eusebio

    2010-10-01

    Acoustic stimuli can evoke reflex EMG responses (acoustic jaw reflex) in the masseter muscle. Although these were previously ascribed to activation of cochlear receptors, high intensity sound can also activate vestibular receptors. Since anatomical and physiological studies, both in animals and humans, have shown that masseter muscles are a target for vestibular inputs we have recently reassessed the vestibular contribution to masseter reflexes. We found that high intensity sound evokes two bilateral and symmetrical short-latency responses in active unrectified masseter EMG of healthy subjects: a high threshold, early p11/n15 wave and a lower threshold, later p16/n21 wave. Both of these reflexes are inhibitory but differ in their threshold, latency and appearance in the rectified EMG average. Experiments in healthy subjects and in patients with selective lesions showed that vestibular receptors were responsible for the p11/n15 wave (vestibulo-masseteric reflex) whereas cochlear receptors were responsible for the p16/n21 wave (acoustic masseteric reflex). The possible functional significance of the double vestibular control over masseter muscles is discussed. PMID:20447862

  18. Variability in Hoffmann and tendon reflexes in healthy male subjects

    NASA Technical Reports Server (NTRS)

    Good, E.; Do, S.; Jaweed, M.

    1992-01-01

    There is a time dependent decrease in amplitude of H- and T-reflexes during Zero-G exposure and subsequently an increase in the amplitude of the H-reflex 2-4 hours after return to a 1-G environment. These alterations have been attributed to the adaptation of the human neurosensory system to gravity. The Hoffman reflex (H-reflex) is an acknowledged method to determine the integrity of the monosynaptic reflex arc. However deep tendon reflexes (DTR's or T-reflexes), elicited by striking the tendon also utilize the entire reflex arc. The objective of this study was to compare the variability in latency and amplitude of the two reflexes in healthy subjects. Methods: Nine healthy male subjects, 27-43 years in age, 161-175 cm in height plus 60-86 Kg in weight, underwent weekly testing for four weeks with a Dan-Tec EMG counterpoint EMG system. Subjects were studied prone and surface EMG electrodes were placed on the right and left soleus muscles. The H-reflex was obtained by stimulating the tibial nerve in the politeal fossa with a 0.2 msec square wave pulse delivered at 2 Hz until the maximum H-reflex was obtained. The T-reflex was invoked by tapping the achilles tendon with a self triggering reflex hammer connected to the EMG system. The latencies and amplitudes for the H- and T-reflexes were measured. Results: These data indicate that the amplitudes of these reflexes varied considerably. However, latencies to invoked responses were consistent. The latency of the T-reflex was approximately 3-5 msec longer than the H-reflex. Conclusion: The T-reflex is easily obtained, requires less time, and is more comfortable to perform. Qualitative data can be obtained by deploying self triggering, force plated reflex hammers both in the 1-G and Zero-G environment.

  19. Spastic long-lasting reflexes in the awake rat after sacral spinal cord injury.

    PubMed

    Bennett, D J; Sanelli, L; Cooke, C L; Harvey, P J; Gorassini, M A

    2004-05-01

    Following chronic sacral spinal cord transection in rats the affected tail muscles exhibit marked spasticity, with characteristic long-lasting tail spasms evoked by mild stimulation. The purpose of the present paper was to characterize the long-lasting reflex seen in tail muscles in response to electrical stimulation of the tail nerves in the awake spastic rat, including its development with time and relation to spasticity. Before and after sacral spinal transection, surface electrodes were placed on the tail for electrical stimulation of the caudal nerve trunk (mixed nerve) and for recording EMG from segmental tail muscles. In normal and acute spinal rats caudal nerve trunk stimulation evoked little or no EMG reflex. By 2 wk after injury, the same stimulation evoked long-lasting reflexes that were 1) very low threshold, 2) evoked from rest without prior EMG activity, 3) of polysynaptic latency with >6 ms central delay, 4) about 2 s long, and 5) enhanced by repeated stimulation (windup). These reflexes produced powerful whole tail contractions (spasms) and developed gradually over the weeks after the injury (< or =52 wk tested), in close parallel to the development of spasticity. Pure low-threshold cutaneous stimulation, from electrical stimulation of the tip of the tail, also evoked long-lasting spastic reflexes, not seen in acute spinal or normal rats. In acute spinal rats a strong C-fiber stimulation of the tip of the tail (20 x T) could evoke a weak EMG response lasting about 1 s. Interestingly, when this C-fiber stimulation was used as a conditioning stimulation to depolarize the motoneuron pool in acute spinal rats, a subsequent low-threshold stimulation of the caudal nerve trunk evoked a 300-500 ms long reflex, similar to the onset of the long-lasting reflex in chronic spinal rats. A similar conditioned reflex was not seen in normal rats. Thus there is an unusually long low-threshold polysynaptic input to the motoneurons (pEPSP) that is normally inhibited by descending control. This pEPSP is released from inhibition immediately after injury but does not produce a long-lasting reflex because of a lack of motoneuron excitability. With chronic injury the motoneuron excitability is increased markedly, and the pEPSP then triggers sustained motoneuron discharges associated with long-lasting reflexes and muscle spasms. PMID:15069102

  20. Studies of the vestibulo-ocular reflex on STS 4, 5 and 6

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Pool, Sam L.; Moore, Thomas P.; Uri, John J.

    1988-01-01

    The vestibulo-ocular reflex (VOR) may be altered by weightlessness. Since this reflex plays a large role in visual stabilization, it was important to document any changes caused by space flight. This is a report on findings on STS-4 through 6 and is part of a larger study of neurosensory adaptation done on STS-4 through 8. Voluntary horizontal head oscillations at 1/3 Hz with amplitude of 30 deg right and left of center were recorded by a potentiometer and compared to eye position recorded by electroculography under the following conditions: eyes open, head fixed, tracking horizontal targets switched 0, 15, and 30 degrees right and left (optokinetic reflex - OKR - and calibration); eyes open and fixed on static external target with oscillation, (vestibulo ocular reflex, eyes closed - VOR EC); eyes open and wearing opaque goggles with target fixed in imagination (vestibulo-ocular reflex, eyes shaded - VOR ES); and eyes open and fixed on a head synchronized target with head oscillation (VOR suppression). No significant changes were found in voluntary head oscillation frequency or amplitude in those with (n=5), and without (n=3), space motion sickness (SMS), with phase of flight or test condition. Variations in head oscillation were too small to have produced detectable changes in test results.

  1. Effects of postural threat on spinal stretch reflexes: evidence for increased muscle spindle sensitivity?

    PubMed

    Horslen, Brian C; Murnaghan, Chantelle D; Inglis, J Timothy; Chua, Romeo; Carpenter, Mark G

    2013-08-01

    Standing balance is often threatened in everyday life. These threats typically involve scenarios in which either the likelihood or the consequence of falling is higher than normal. When cats are placed in these scenarios they respond by increasing the sensitivity of muscle spindles imbedded in the leg muscles, presumably to increase balance-relevant afferent information available to the nervous system. At present, it is unknown whether humans also respond to such postural threats by altering muscle spindle sensitivity. Here we present two studies that probed the effects of postural threat on spinal stretch reflexes. In study 1 we manipulated the threat associated with an increased consequence of a fall by having subjects stand at the edge of an elevated surface (3.2 m). In study 2 we manipulated the threat by increasing the likelihood of a fall by occasionally tilting the support surface on which subjects stood. In both scenarios we used Hoffmann (H) and tendon stretch (T) reflexes to probe the spinal stretch reflex circuit of the soleus muscle. We observed increased T-reflex amplitudes and unchanged H-reflex amplitudes in both threat scenarios. These results suggest that the synaptic state of the spinal stretch reflex is unaffected by postural threat and that therefore the muscle spindles activated in the T-reflexes must be more sensitive in the threatening conditions. We propose that this increase in sensitivity may function to satisfy the conflicting needs to restrict movement with threat, while maintaining a certain amount of sensory information related to postural control. PMID:23719208

  2. Neural reflexes in inflammation and immunity

    PubMed Central

    2012-01-01

    The mammalian immune system and the nervous system coevolved under the influence of infection and sterile injury. Knowledge of homeostatic mechanisms by which the nervous system controls organ function was originally applied to the cardiovascular, gastrointestinal, musculoskeletal, and other body systems. 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. Such reflexes are evolutionarily ancient, dating back to invertebrate nematode worms that possess primitive immune and nervous systems. Failure of these reflex mechanisms in mammals contributes to nonresolving inflammation and disease. It is also possible to target these neural pathways using electrical nerve stimulators and pharmacological agents to hasten the resolution of inflammation and provide therapeutic benefit. PMID:22665702

  3. Running title: sound-evoked vestibulomasseteric reflex

    E-print Network

    Franca Deriu; Eusebio Tolu; John C. Rothwell

    Copyright © 2004 by the American Physiological Society. 1 Averaged responses to loud clicks were recorded in the unrectified and rectified masseter EMG of 18 healthy subjects. Unilateral clicks (0.1 ms, 3 Hz, 70-100 dB NHL), delivered during a steady masseter contraction evoked bilateral responses that appeared to consist of two components on the basis of threshold, latency, and their appearance in rectified EMG. The lowest threshold response appeared as a p16 wave (onset 11-13 ms) in the unrectified EMG and corresponded with a 10-12 ms period of inhibition in the rectified EMG. Higher intensity clicks recruited an earlier p11 response in the unrectified EMG (onset 7.0-9.2 ms) that sometimes appeared as initial increase in the rectified EMG prior to suppression. The amplitude of the p11 wave scaled with background EMG level and was asymmetrically modulated by 30 ° tilt of the whole body. The threshold of the early p11/n15 wave in masseter was the same as the threshold for click-induced vestibulocollic reflexes. Single motor unit recordings demonstrated that responses in masseters corresponded to a silent period in unit firing which began earlier and lasted longer at 100 dB than at 80 dB. We propose that loud clicks induce two partially overlapping short-latency reflexes in masseter muscle EMG: a p11/n15 response which we suggest is of vestibular origin and a p16/n21 response which we suggest is equivalent to the previously described jaw-acoustic reflex. KEY WORDS: sound-induced reflexes; clicks; masseter muscles; vestibular reflexes; cochlear reflexes2

  4. Long-term depression-like plasticity of the blink reflex for the treatment of blepharospasm.

    PubMed

    Kranz, Gottfried; Shamim, Ejaz A; Lin, Peter T; Kranz, George S; Hallett, Mark

    2013-04-01

    Our previous work showed a beneficial therapeutic effect on blepharospasm using slow repetitive transcranial magnetic stimulation, which produces a long-term depression (LTD)-like effect. High-frequency supraorbital electrical stimulation, asynchronous with the R2 component of the blink reflex, can also induce LTD-like effects on the blink reflex circuit in healthy subjects. Patients with blepharospasm have reduced inhibition of their blink recovery curves; therefore, a LTD-like intervention might normalize the blink reflex recovery (BRR) and have a favorable therapeutic effect. This is a randomized, sham-controlled, observer-blinded prospective study. In 14 blepharospasm patients, we evaluated the effects of high-frequency supraorbital stimulation on three separate treatment days. We applied 28 trains of nine stimuli, 400 Hz, either before or after the R2 or used sham stimulation. The primary outcome was the blink rate, number of spasms rated by a blinded physician and patient rating before, immediately after and 1 hour after stimulation while resting, reading, and talking; secondary outcome was the BRR. Stimulation "before" and "after" the R2 both showed a similar improvement as sham stimulation in physician rating, but patients felt significantly better with the before condition. Improvement in recovery of the blink reflex was noted only in the before condition. Clinical symptoms differed in the three baseline conditions (resting, reading, and talking). Stimulation before R2 increased inhibition in trigeminal blink reflex circuits in blepharospasm toward normal values and produced subjective, but not objective, improvement. Inhibition of the blink reflex pathway by itself appeared to be insufficient for a useful therapeutic effect. PMID:23401198

  5. Vagal gustatory reflex circuits for intraoral food sorting behavior in the goldfish Cellular organization and neurotransmitters

    PubMed Central

    Ikenaga, Takanori; Ogura, Tatsuya; Finger, Thomas E.

    2009-01-01

    The sense of taste is crucial in an animal’s determination as to what is edible and what is not. This gustatory function is especially important in goldfish who utilize a sophisticated oropharyngeal sorting mechanism to separate food from substrate material. The computational aspects of this detection are carried out by the medullary vagal lobe which is a large, laminated structure combining elements of both the gustatory nucleus of the solitary tract and the nucleus ambiguus. The sensory layers of the vagal lobe are coupled to the motor layers via a simple reflex arc. Details of this reflex circuit were investigated with histology and calcium imaging. Biocytin injections into the motor layer labeled vagal reflex interneurons which have radially-directed dendrites ramifying within the layers of primary afferent terminals. Axons of reflex interneurons extend radially inward to terminate onto both vagal motoneurons and small, GABAergic interneurons in the motor layer. Functional imaging shows increases in intracellular Ca++ of vagal motoneurons following electrical stimulation in the sensory layer. These responses were suppressed under Ca++-free conditions and by interruption of the axons bridging between the sensory and motor layers. Pharmacological experiments showed that glutamate acting via (±)-?-amino-3-hydroxy-5-ethylisoxazole-4-propioinc acid (AMPA)/kainate and N-methyl-D-aspartic acid (NMDA) receptors mediates neurotransmission between reflex interneurons and vagal motoneurons. Thus the vagal gustatory portion of the viscerosensory complex is linked to branchiomotor neurons of the pharynx via a glutamatergic interneuronal system. PMID:19598285

  6. Resolution of hypothyroidism after correction of somatovisceral reflex dysfunction by refusion of the cervical spine.

    PubMed

    Berkowitz, Murray R

    2015-01-01

    Psychosis is a rare initial presentation of new-onset hypothyroidism. The author describes the case of a 29-year-old woman who presented with psychosis caused by hypothyroidism, or myxedema madness. Although the patient's psychosis resolved after standard monotherapy using levothyroxine sodium, her hypothyroidism persisted. Imaging of the patient's cervical spine showed that previous C5-C6 and C6-C7 fusions had failed. The failed fusions were corrected, and the patient's hypothyroidism resolved, suggesting that the somatovisceral reflex was the cause of the patient's hypothyroidism. Although somatovisceral reflex dysfunctions are rare, physicians should consider them as potential underlying causes of their patients' presenting medical conditions. PMID:25550492

  7. Using electrically evoked auditory reflex thresholds to fit the CLARION cochlear implant.

    PubMed

    Hodges, A V; Butts, S; Dolan-Ash, S; Balkany, T J

    1999-04-01

    This paper describes a method for measuring electrically elicited auditory reflex thresholds (EARTs) in young children who use the CLARION Multi-Strategy Cochlear Implant. The EART is an objective measure that can guide the fitting of a cochlear implant in individuals who are unable to perform behavioral tasks required to program the device. Reflexes were obtained in 11 of 17 pediatric Clarion users. The EART current level indicated a point at which an auditory percept was present and the sound was loud, but not uncomfortable. The EART then was used as a basis for conditioning behavioral responses, and as a guideline for setting most comfortable loudness levels. PMID:10214804

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

    ERIC Educational Resources Information Center

    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…

  9. Ethnic and Gender Differences in Cough Reflex Sensitivity

    Microsoft Academic Search

    Peter V. Dicpinigaitis; Valerie R. C. Allusson; Annmarie Baldanti; Jhansi R. Nalamati

    2001-01-01

    Background: Although recent studies have suggested that the cough reflex is more sensitive in women than in men, ethnic differences in cough reflex sensitivity have not previously been investigated. Objectives: To evaluate ethnic and gender differences in cough reflex sensitivity. Methods: We performed capsaicin cough challenge testing in 182 healthy volunteers of three distinct ethnic groups: Caucasian (white, non-Hispanic, of

  10. Reflexive Modernity, Self-Reflective Biographies: Adult Education in the Light of the Risk Society.

    ERIC Educational Resources Information Center

    Jansen, Theo; van der Veen, Ruud

    1992-01-01

    The risk society characterized by reflexive modernization features individualization; rather than being controlled by social conditioning, individuals make their own life decisions. The ambiguous nature of this process is a challenge to adult education and applications of traditional life course theories. (SK)

  11. Noradrenergic Modulation of the Masseteric Reflex in Behaving Cats. II. Physiological Studies

    Microsoft Academic Search

    L. Stafford; Barry L. Jacobs

    Studies in the preceding paper demonstrated that the am- plitude of the masseteric reflex in behaving cats is aug- mented by pharmacological manipulations that increase nor- epinephrine (NE) tone in the motor trigeminal nucleus (MoV) through exogenous means. The present studies examine whether such a relationship also exists under physiological conditions, i.e., whether physiological increases in NE syn- aptic activity

  12. The effect of increased pressure in the cavities of the alimentary tract on evoked reflexes. Report 2: The effect on Proprioceptive cervical and lumbar compensatory reflexes

    NASA Technical Reports Server (NTRS)

    Komendantov, G. L.

    1973-01-01

    Changes occurring in the cervical ocular reflexes and in the lumbar ocular reflexes following an increase in gastric pressure were studied. The lumbar reflexes were subject to the most pronounced after effect. The pressure increase caused greater changes in the cervical ocular reflexes. It was concluded that all reflexes were affected to some extent.

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

    PubMed Central

    Meskers, Carel GM; Schouten, Alfred C; de Groot, Jurriaan H; de Vlugt, Erwin; van Hilten, Bob JJ; van der Helm, Frans CT; Arendzen, Hans JH

    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 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. PMID:19627607

  14. Acousticomotor reflexes M Dolores E. Lpez Garca

    E-print Network

    Oliver, Douglas L.

    by sounds that are:that are: - low-intensity (of any frequency) - high-frequency (of any intensity) - short hair cells »a better perception of loud sound #12;Contraction as a function of intensity and frequency-ear reflexes are activated by sounds that are:are: 1 - loud (> 80dB) - low-frequency (

  15. Taking Control of Reflexive Social Attention

    ERIC Educational Resources Information Center

    Ristic, Jelena; Kingstone, Alan

    2005-01-01

    Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the…

  16. Is Inhibition of Return a Reflexive Effect?

    ERIC Educational Resources Information Center

    Tipper, Christine; Kingstone, Alan

    2005-01-01

    The inhibition of return (IOR) phenomenon is routinely considered an effect of reflexive attention because the paradigm used to generate IOR employs peripheral cues that are uninformative as to where a target will appear. Because the cues are spatially unreliable it is thought that there is no reason for attention to be committed volitionally to…

  17. Reflectivity, Reflexivity and Situated Reflective Practice

    ERIC Educational Resources Information Center

    Malthouse, Richard; Roffey-Barentsen, Jodi; Watts, Mike

    2014-01-01

    This paper describes an aspect of reflective practice referred to as situated reflective practice. The overarching theory is derived from social theories of structuration and reflexivity. In particular, from Giddens' theory of structuration, which sees social life as an interplay of agency and structure. Discussion of the research reported…

  18. THE SEQUELAE OF REFLEX SYMPATHETIC DYSTROPHY

    Microsoft Academic Search

    A. ZYLUK

    2001-01-01

    This paper presents the results of a retrospective analysis of 94 patients who were assessed at a mean of 11 months after successful treatment of reflex sympathetic dystrophy (RSD) of the hand. Fifty-four percent still complained of pain related to the weather, and many complained of cold intolerance (44%), slight pain after use (34%), nail and hair growth changes (34%),

  19. Reflex Anuria After Renal Tumor Embolization

    SciTech Connect

    Kervancioglu, Selim, E-mail: skervancioglu@yahoo.com; Sirikci, Akif [Gaziantep University, Department of Radiology, Faculty of Medicine (Turkey); Erbagci, Ahmet [Gaziantep University, Department of Urology, Faculty of Medicine (Turkey)

    2007-04-15

    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.

  20. Reflex sympathetic dystrophy: changing concepts and taxonomy

    Microsoft Academic Search

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

    1995-01-01

    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

  1. Perspective on the human cough reflex

    PubMed Central

    2011-01-01

    This review dissects the complex human cough reflex and suggests hypotheses about the evolutionary basis for the reflex. A mechanosensory-induced cough reflex conveys through branches of myelinated A? nerve fibers is not chemically reactive (i.e., capsaicin, bradykinin); possibly, its evolution is to prevent the harmful effects of aspiration of gastric or particulate contents into the lungs. This became necessary as the larynx moves closer to the opening of the esophagus as human ancestors adapt phonation over olfaction beginning less than 10 million years ago. The second type of cough reflex, a chemosensory type, is carried by unmyelinated C fibers. Supposedly, its origin dates back when prehistoric humans began living in close proximity to each other and were at risk for infectious respiratory diseases or irritant-induced lung injury. The mechanism for the latter type of cough is analogous to induced pain after tissue injury; and, it is controlled by the identical transient receptor potential vanilloid cation channel (TRPV1). The airways do not normally manifest nociceptive pain from a stimulus but the only consistent response that capsaicin and lung inflammation provoke in healthy human airways is cough. TRPA1, another excitatory ion channel, has been referred to as the "irritant receptor" and its activation also induces cough. For both types of cough, the motor responses are identical and via coordinated, precisely-timed and sequential respiratory events orchestrated by complex neuromuscular networking of the diaphragm, chest and abdominal respiratory muscles, the glottis and parts of the brain. PMID:22074326

  2. Biological Motion Cues Trigger Reflexive Attentional Orienting

    ERIC Educational Resources Information Center

    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…

  3. Intrathecal baclofen and the H-reflex

    Microsoft Academic Search

    R A Macdonell; A Talalla; M Swash; D Grundy

    1989-01-01

    Baclofen was given intrathecally to six patients with severe lower limb spasticity due to traumatic spinal cord injury. The effects of the drug on spasticity and the ratio between the maximum amplitude of the H reflex and the M response from the soleus (Hmax\\/Mmax ratio) were assessed. In each patient, spasticity was reduced following intrathecal baclofen and in four patients

  4. Dilemmas and Deliberations in Reflexive Ethnographic Research

    ERIC Educational Resources Information Center

    Robinson, Janean Valerie

    2014-01-01

    This paper traces insights into the challenges and dilemmas experienced whilst researching students' interpretations and understandings of the Behaviour Management in Schools policy in Western Australia. Journal records, supported by student transcripts, are woven together in a reflexive ethnographic journey--from the beginning phase of…

  5. Effects of exercise pressor reflex activation on carotid baroreflex function during exercise in humans

    NASA Technical Reports Server (NTRS)

    Gallagher, K. M.; Fadel, P. J.; Stromstad, M.; Ide, K.; Smith, S. A.; Querry, R. G.; Raven, P. B.; Secher, N. H.

    2001-01-01

    1. This investigation was designed to determine the contribution of the exercise pressor reflex to the resetting of the carotid baroreflex during exercise. 2. Ten subjects performed 3.5 min of static one-legged exercise (20 % maximal voluntary contraction) and 7 min dynamic cycling (20 % maximal oxygen uptake) under two conditions: control (no intervention) and with the application of medical anti-shock (MAS) trousers inflated to 100 mmHg (to activate the exercise pressor reflex). Carotid baroreflex function was determined at rest and during exercise using a rapid neck pressure/neck suction technique. 3. During exercise, the application of MAS trousers (MAS condition) increased mean arterial pressure (MAP), plasma noradrenaline concentration (dynamic exercise only) and perceived exertion (dynamic exercise only) when compared to control (P < 0.05). No effect of the MAS condition was evident at rest. The MAS condition had no effect on heart rate (HR), plasma lactate and adrenaline concentrations or oxygen uptake at rest and during exercise. The carotid baroreflex stimulus-response curve was reset upward on the response arm and rightward to a higher operating pressure by control exercise without alterations in gain. Activation of the exercise pressor reflex by MAS trousers further reset carotid baroreflex control of MAP, as indicated by the upward and rightward relocation of the curve. However, carotid baroreflex control of HR was only shifted rightward to higher operating pressures by MAS trousers. The sensitivity of the carotid baroreflex was unaltered by exercise pressor reflex activation. 4. These findings suggest that during dynamic and static exercise the exercise pressor reflex is capable of actively resetting carotid baroreflex control of mean arterial pressure; however, it would appear only to modulate carotid baroreflex control of heart rate.

  6. Yaw sensory rearrangement alters pitch vestibulo-ocular reflex responses

    NASA Technical Reports Server (NTRS)

    Petropoulos, A. E.; Wall, C. 3rd; Oman, C. M.

    1997-01-01

    Ten male subjects underwent two types of adaptation paradigm designed either to enhance or to attenuate the gain of the canal-ocular reflex (COR), before undergoing otolith-ocular reflex (OOR) testing with constant velocity, earth horizontal axis and pitch rotation. The adaptation paradigm paired a 0.2 Hz sinusoidal rotation about an earth vertical axis with a 0.2 Hz optokinetic stimulus that was deliberately mismatched in peak velocity or phase and was designed to produce short-term changes in the COR. Preadaptation and postadaptation OOR tests occurred at a constant velocity of 60 degrees/sec in the dark and produced a modulation component of the slow phase velocity with a frequency of 0.16 Hz due to otolithic stimulation by the sinusoidally changing gravity vector. Of the seven subjects who showed enhancement of the COR gain, six also showed enhancement of the OOR modulation component. Of the seven subjects who showed attenuation of the COR gain, five also showed attenuation of the OOR modulation component. The probability that these two cross-axis adaptation effects would occur by chance is less than 0.02. This suggests that visual-vestibular conditioning of the yaw axis COR also induced changes in the pitch axis OOR. We thus postulate that the central nervous system pathways that process horizontal canal yaw stimuli have elements in common with those processing otolithic stimuli about the pitch axis.

  7. Acceleration dependence and task-specific modulation of short- and medium-latency reflexes in the ankle extensors

    PubMed Central

    Finley, James M; Dhaher, Yasin Y; Perreault, Eric J

    2013-01-01

    Involuntary responses to muscle stretch are often composed of a short-latency reflex (SLR) and more variable responses at longer latencies such as the medium-latency (MLR) and long-latency stretch reflex (LLR). Although longer latency reflexes are enhanced in the upper limb during stabilization of external loads, it remains unknown if they have a similar role in the lower limb. This uncertainty results in part from the inconsistency with which longer latency reflexes have been observed in the lower limb. A review of the literature suggests that studies that only observe SLRs have used perturbations with large accelerations, possibly causing a synchronization of motoneuron refractory periods or an activation of force-dependent inhibition. We therefore hypothesized that the amplitude of longer latency reflexes would vary with perturbation acceleration. We further hypothesized that if longer latency reflexes were elicited, they would increase in amplitude during control of an unstable load, as has been observed in the upper limb. These hypotheses were tested at the ankle while subjects performed a torque or position control task. SLR and MLR reflex components were elicited by ankle flexion perturbations with a fixed peak velocity and variable acceleration. Both reflex components initially scaled with acceleration, however, while the SLR continued to increase at high accelerations, the MLR weakened. At accelerations that reliably elicited MLRs, both the SLR and MLR were reduced during control of the unstable load. These findings clarify the conditions required to elicit MLRs in the ankle extensors and provide additional evidence that rapid feedback pathways are downregulated when stability is compromised in the lower limb. PMID:24303134

  8. Context-Specific Adaptation of Gravity-Dependent Vestibular Reflex Responses (NSBRI Neurovestibular Project 1)

    NASA Technical Reports Server (NTRS)

    Shelhamer, Mark; Goldberg, Jefim; Minor, Lloyd B.; Paloski, William H.; Young, Laurence R.; Zee, David S.

    1999-01-01

    Impairment of gaze and head stabilization reflexes can lead to disorientation and reduced performance in sensorimotor tasks such as piloting of spacecraft. Transitions between different gravitoinertial force (gif) environments - as during different phases of space flight - provide an extreme test of the adaptive capabilities of these mechanisms. We wish to determine to what extent the sensorimotor skills acquired in one gravity environment will transfer to others, and to what extent gravity serves as a context cue for inhibiting such transfer. We use the general approach of adapting a response (saccades, vestibuloocular reflex: VOR, or vestibulocollic reflex: VCR) to a particular change in gain or phase in one gif condition, adapting to a different gain or phase in a second gif condition, and then seeing if gif itself - the context cue - can recall the previously-learned adapted responses. Previous evidence indicates that unless there is specific training to induce context-specificity, reflex adaptation is sequential rather than simultaneous. Various experiments in this project investigate the behavioral properties, neurophysiological basis, and anatomical substrate of context-specific learning, using otolith (gravity) signals as a context cue. In the following, we outline the methods for all experiments in this project, and provide details and results on selected experiments.

  9. A new model of the acoustic reflex.

    PubMed

    Longtin, A; Derome, J R

    1986-01-01

    A system-type model of the acoustic reflex in man is proposed with the intention of sheding light on certain of its nonlinear behaviors. This model is the first to incorporate into the multipath structure of the reflex arc the adaptation and recovery processes. Parameter distribution in the parallel pathways is based on the current knowledge on the stapedius muscle and on motoneuron pool organization. A piecewise linear system is used in modeling adaptation at onset and recovery at offset. The model is calibrated at 2000 Hz, a frequency for which all the important parameters are available. Two nonlinear behaviors of the adaptation rate are explained: the frequency and intensity dependence, related respectively to the frequency dependence of the feedback gain and to the sigmoidal shape of the closed-loop stimulus-response curve. Underlying physiological mechanisms are discussed, along with other plausible nonlinear models, and extensions of the model to other stimuli are suggested. PMID:3697403

  10. Why Unergatives Select Themselves a Fake Reflexive

    E-print Network

    Grove, Kyle Wade

    2008-01-01

    of the fake reflexive in a small clause is epiphenomonal from a relationship between initiation and delimitation, and has less to do with secondary predication. • Hypothesis 2: If vDO is in fact the correct light verb in a-c, then ‘itself’ should be assigned a.... The following is a naive neo-Davidsonian analysis of secondary predicative fake reflexives. (29) a. The Flash danced himself sick. b. ?e1?e2?x?y?s(Flash(x)?Causer(x,e1)?Cause(e1,e2)?Flash(y)? Actor(y,e2) ? Dance(e2) ?Cul(e2,s) ?Theme(y,s) ?Sick(s)) 4Notably...

  11. Regional cerebral perfusion in cardiovascular reflex syncope

    Microsoft Academic Search

    Jari P. Töyry; Jyrki T. Kuikka; Esko A. Länsimies

    1997-01-01

    Little is known about the regional cerebral perfusion in subjects with presyncope or syncope, and the impact that autonomic\\u000a nervous dysfunction has on it. Seven subjects with cardiovascular vasodepressor reflex syncope were studied. A baseline test\\u000a was performed with the patients standing in the 70° upright position, while the passive head-up tilt table test with and without\\u000a isoprenaline infusion was

  12. A reflexive model for teaching instructional design

    Microsoft Academic Search

    Neal Shambaugh; Susan Magliaro

    2001-01-01

    Although there are numerous models to practive instructional design (ID), few instructional models to teach instructional\\u000a design have been documented. This article documents a five-year study of two instructors who collaborated on formally studying\\u000a their teaching of a master's level instructional design course. A reflexive instructional approach was used, in which the\\u000a teachers examined their teaching while students were being

  13. Basic Gravitational Reflexes in the Larval Frog

    NASA Technical Reports Server (NTRS)

    Cochran, Stephen L.

    1996-01-01

    This investigation was designed to determine how a primitive vertebrate, the bullfrog tadpole, is able to sense and process gravitational stimuli. Because of the phylogenetic similarities of the vestibular systems in all vertebrates, the understanding of the gravitational reflexes in this relatively simple vertebrate should elucidate a skeletal framework on a elementary level, upon which the more elaborate reflexes of higher vertebrates may be constructed. The purpose of this study was to understand how the nervous system of the larval amphibian processes gravitational information. This study involved predominantly electrophysiological investigations of the isolated, alert (forebrain removed) bullfrog tadpole head. The focus of these experiments is threefold: (1) to understand from whole extraocular nerve recordings the signals sent to the eye following static gravitational tilt of the head; (2) to localize neuronal centers responsible for generating these signals through reversible pharmacological ablation of these centers; and (3) to record intracellularly from neurons within these centers in order to determine the single neuron's role in the overall processing of the center. This study has provided information on the mechanisms by which a primitive vertebrate processes gravitational reflexes.

  14. Conditionals

    E-print Network

    von Fintel, Kai

    2011-01-01

    This article introduces the classic accounts of the meaning of conditionals (material implication, strict implication, variably strict conditional) and discusses the difference between indicative and subjunctive/counterfactual ...

  15. Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes?

    PubMed Central

    Feys, Peter; Helsen, Werner; Ilsbroukx, Stephan; Meurrens, Tom

    2011-01-01

    Intention tremor is related to lesions in the cerebellum or connected pathways. Intention tremor amplitude decreased after peripheral arm cooling in patients with multiple sclerosis (MS), likely caused by a reduction of muscle spindle afferent inflow, while amplitude increased when muscle spindles were artificially stimulated by tendon vibration. This study investigated the contribution of peripheral reflexes to the generation of MS intention tremor. Tendon reflexes of biceps, triceps, and brachioradialis, muscles were measured, using an electromechanical triggered reflex hammer. MS patients with (n = 17) and without (n = 17) upper limb intention and 18 healthy controls were tested. Latency of brachioradialis, biceps, and triceps tendon reflexes was greater in MS patients with tremor than in healthy controls and MS patients without tremor (except for the triceps reflex). Peak and peak-to-peak amplitude were not different between groups. It is concluded that tendon reflexes were delayed but not enlarged in MS patients with tremor. PMID:22389808

  16. Reflex Sympathetic Dystrophy: Recognition and Management for the Physician

    Microsoft Academic Search

    Edward Carden

    ABSTRACT Reflex Sympathetic,Dystrophy is a dysfunctional pain response,to a noxious stimulus. It is characterized by pain out of proportion to the inciting event, which may be quite insignificant but can be severe. In its earliest stages reflex sympathetic,dystrophy,is responsive to sympathetic blockade, pharmacologic agents, other modalities, and physical therapy. Early recognition and treatment is critical, because unrecognized reflex sympathetic dystrophy

  17. Absent vestibulo-ocular reflexes and acute supratentorial lesions1

    PubMed Central

    Rosenberg, Michael; Sharpe, James; Hoyt, William F.

    1975-01-01

    Loss of vestibulo-ocular reflexes occurred in two patients with acute supratentorial lesions who received therapeutic doses of anticonvulsant drugs. There was no clinical or angiographic evidence of focal brain-stem damage. Absence of vestibulo-ocular reflexes is attributed to a combination of acute cerebral damage and anticonvulsant drugs. The loss of these reflexes in patients with acute cerebral lesions cannot be interpreted as evidence of irreversible brain-stem injury. PMID:1078843

  18. Context-Specific Adaptation of Gravity-Dependent Vestibular Reflex Responses

    NASA Technical Reports Server (NTRS)

    Shelhamer, Mark J.

    1999-01-01

    Stabilization of the eyes and head during body movements is important for maintaining balance and keeping the images of objects stationary on our retinas. Impairment of this ability can lead to disorientation and reduced performance in sensorimotor tasks such as piloting of spacecraft. In the absence of a normal earth gravity field, the dynamics of head stabilization, and the interpretation of vestibular signals that sense gravity and linear acceleration, are subject to change. Transitions between different gravitoinertial force environments - as during different phases of space flight - provide an extreme test of the adaptive mechanisms that maintain these reflexive abilities. It is vitally important to determine human adaptive capabilities in such a circumstance, so that we can know to what extent the sensorimotor skills acquired in one gravity environment will transfer to others. Our work lays the foundation for understanding these capabilities, and for determining how we can aid the processes of adaptation and readaptation. An integrated set of experiments addresses this issue. We use the general approach of adapting some type of reflexive eye movement (saccades, the angular vestibulo-ocular reflex (AVOR), the linear vestibulo-ocular reflex (LVOR)), or the vestibulo-collic reflex (VCR), to a particular change in gain or phase in one condition of gravitoiner-tial force, and adapting to a different gain or phase (or asking for no change) in a second gravitoinertial force condition, and then seeing if the gravitoinertial force itself - the context cue - can recall the previously learned adapted responses. The majority of the experiments in the laboratory use the direction of vertical gaze or the direction of gravity (head tilt) as the context cue. This allows us to study context-specificity in a ground-based setting. One set of experiments, to be performed in parabolic flight, specifically uses the magnitude of gravitoinertial force as a context cue. This is a much better analog of the situation encountered in space flight. Various experiments investigate the behavioral properties, neurophysiological basis, and anatomical substrate of context-specific learning mechanisms. We use otolith (gravity) signals as the contextual cue for switching between adapted states of the saccadic system, the angular and linear vestibulo-ocular reflexes, and the VCR. (By LVOR we mean the oculomotor response - horizontal, vertical, and torsional - to linear translation of the head and body.) We are studying the effect of context on adaptation of saccade gain, phase and gain of the AVOR and LVOR, on ocular counterrolling (OCR) in response to static head tilt, and on head/neck reflexes (VCR) in response to rotation in different orientations. Such research is particularly germane to potential problems of postural and oculomotor control upon exposure to different gravitational environments.

  19. The "where is it?" reflex: autoshaping the orienting response.

    PubMed Central

    Buzsáki, G

    1982-01-01

    The goal of this review is to compare two divergent lines of research on signal-centered behavior: the orienting reflex (OR) and autoshaping. A review of conditioning experiments in animals and humans suggests that the novelty hypothesis of the OR is no longer tenable. Only stimuli that represent biological "relevance" elicit ORs. A stimulus may be relevant a priori (i.e., unconditioned) or as a result of conditioning. Exposure to a conditioned stimulus (CS) that predicts a positive reinforcer causes the animal to orient to it throughout conditioning. Within the CS-US interval, the initial CS-directed orienting response is followed by US-directed tendencies. Experimental evidence is shown that the development and maintenance of the conditioned OR occur in a similar fashion both in response-independent (classical) and response-dependent (instrumental) paradigms. It is proposed that the conditioned OR and the signal-directed autoshaped response are identical. Signals predicting aversive events repel the subject from the source of the CS. It is suggested that the function of the CS is not only to signal the probability of US occurrence, but also to serve as a spatial cue to guide the animal in the environment. PMID:7097153

  20. Sensitivity of monosynaptic test reflexes to facilitation and inhibition as a function of the test reflex size: a study in man and the cat

    Microsoft Academic Search

    C. Crone; H. Hultborn; L. Mazières; C. Morin; J. Nielsen; E. Pierrot-Deseilligny

    1990-01-01

    In parallel experiments on humans and in the cat it was investigated how the sensitivity of monosynaptic test reflexes to facilitation and inhibition varies as a function of the size of the control test reflex itself. In man the monosynaptic reflex (the Hoffmann reflex) was evoked in either the soleus muscle (by stimulation of the tibial nerve) or the quadriceps

  1. Stretch sensitive reflexes as an adaptive mechanism for maintaining limb stability

    E-print Network

    Perreault, Eric J.

    , Northwestern University Abstract The often studied stretch reflex is fundamental to the involuntary control interactions with compliant environments, relative to the sensitivity during interactions with rigid reflex; long latency; adaptation; impedance; stiffness Introduction Observations of stretch reflexes

  2. Suppressive influences from periaqueductal gray and nucleus raphe magnus on respiration and related reflex activities and on solitary tract neurons, and effect of naloxone.

    PubMed

    Sessle, B J; Ball, G J; Lucier, G E

    1981-07-01

    Possible opiate-related descending influences from the periaqueductal gray matter (PAG) and nucleus raphe magnus (NRM) were tested on the activity of neural systems involved in respiration and related reflex functions in cats. Stimulation of PAG and NRM could powerfully suppress the simple buccopharyngeal reflexes of jaw-opening and tongue-protrusion and the more complex reflexes of coughing and swallowing; respiration in contrast appeared to be only weakly influenced. The reflexly induced responses of 57 single reflex interneurons recorded in the solitary tract nucleus (NST) could also be markedly suppressed by PAG and NRM conditioning stimulation. In contrast, the rhythmic activity of 30 respiratory neurons in NST was not abolished by PAG and NRM stimuli but most did show a decrease in the peak firing frequency of each rhythmic burst. The suppressive effect of PAG and NRM stimulation on the reflexes and NST reflex interneurons could be reduced by the intravenous administration of naloxone. These studies indicate that neuronal functions associated with respiration and respiratory-related activities can be suppressed by descending influences from PAG and NRM that are in part opiate-related. The observations add to the accumulating evidence that the raphe system is implicated in functions other than pain and its control, and they may also be relevant to clinical observations of opiate-induced effects on respiration and the cough reflex. PMID:6266582

  3. Characterizing FluidReflex Optical Transfer Function

    NASA Astrophysics Data System (ADS)

    Victoria, Marta; Domínguez, César; Askins, Steve; Antón, Ignacio; Sala, Gabriel

    2012-10-01

    FluidReflex is a novel concentrator concept that has been designed to achieve a low cost concentration photovoltaic (CPV) system over 1000× by using reflective optics and a fluid dielectric. In this paper, results regarding the characterization of the concentrator Optical Transfer Function (OTF) are presented. The reflectance and transmittance of the different materials that the concentrator is composed of have been measured using a spectrometer. In addition, a method using component cells (isotypes) has been used to experimentally determine which of the subcells within the multijunction (MJ) solar cell is limiting the current when it is illuminated by the concentrator.

  4. Multi-MA reflex triode research.

    SciTech Connect

    Swanekamp, Stephen Brian (Naval Research Laboratory, Washington, DC); Commisso, Robert J. (Naval Research Laboratory, Washington, DC); Weber, Bruce V. (Naval Research Laboratory, Washington, DC); Riordan, John C. (L-3 Pulse Sciences Division, San Leandro, CA); Allen, Raymond J. (Naval Research Laboratory, Washington, DC); Goyer, John R. (L-3 Pulse Sciences Division, San Leandro, CA); Murphy, Donald P. (Naval Research Laboratory, Washington, DC); Mikkelson, Kenneth A.; Harper-Slaboszewicz, Victor Jozef

    2010-08-01

    The Reflex Triode can efficiently produce and transmit medium energy (10-100 keV) x-rays. Perfect reflexing through thin converter can increase transmission of 10-100 keV x-rays. Gamble II experiment at 1 MV, 1 MA, 60 ns - maximum dose with 25 micron tantalum. Electron orbits depend on the foil thickness. Electron orbits from LSP used to calculate path length inside tantalum. A simple formula predicts the optimum foil thickness for reflexing converters. The I(V) characteristics of the diode can be understood using simple models. Critical current dominates high voltage triodes, bipolar current is more important at low voltage. Higher current (2.5 MA), lower voltage (250 kV) triodes are being tested on Saturn at Sandia. Small, precise, anode-cathode gaps enable low impedance operation. Sample Saturn results at 2.5 MA, 250 kV. Saturn dose rate could be about two times greater. Cylindrical triode may improve x-ray transmission. Cylindrical triode design will be tested at 1/2 scale on Gamble II. For higher current on Saturn, could use two cylindrical triodes in parallel. 3 triodes in parallel require positive polarity operation. 'Triodes in series' would improve matching low impedance triodes to generator. Conclusions of this presentation are: (1) Physics of reflex triodes from Gamble II experiments (1 MA, 1 MV) - (a) Converter thickness 1/20 of CSDA range optimizes x-ray dose; (b) Simple model based on electron orbits predicts optimum thickness from LSP/ITS calculations and experiment; (c) I(V) analysis: beam dynamics different between 1 MV and 250 kV; (2) Multi-MA triode experiments on Saturn (2.5 MA, 250 kV) - (a) Polarity inversion in vacuum, (b) No-convolute configuration, accurate gap settings, (c) About half of current produces useful x-rays, (d) Cylindrical triode one option to increase x-ray transmission; and (3) Potential to increase Saturn current toward 10 MA, maintaining voltage and outer diameter - (a) 2 (or 3) cylindrical triodes in parallel, (b) Triodes in series to improve matching, (c) These concepts will be tested first on Gamble II.

  5. Effects of a distant noxious stimulation on A and C fibre-evoked flexion reflexes and neuronal activity in the dorsal horn of the rat.

    PubMed

    Schouenborg, J; Dickenson, A

    1985-02-25

    In the halothane-anaesthetized rat, the responses of 49 neurons in the lumbo-sacral cord and the reflex discharge in the common peroneal nerve following electrical stimulation of the sural nerve were recorded in order to study possible relations between neuronal events and reflex nerve discharges. A distant noxious stimulus (to activate Diffuse Noxious Inhibitory Controls (DNIC) of Le Bars et al.) was used as a conditioning stimulus. Only the responses of neurons receiving an input from both A and C fibres were studied. The neurons were classified as class 1 (low threshold mechanoreceptive input only, n = 2), class 2 (nonnoxious and noxious inputs, n = 34) or class 3 (responding to noxious stimuli only, n = 13). During conditioning stimulation the C fibre evoked discharge was inhibited in 32 out of 34 class 2 neurons. The A fibre-evoked discharge was simultaneously inhibited in 29 of these neurons. The main effect of the distant noxious stimulation on the C fibre evoked neuronal discharge was to decrease the discharge by a constant number of spikes, independent of the level of evoked activity. Only one class 3 neuron was inhibited during conditioning stimulation and none of the class 1 cells were influenced by DNIC. During conditioning stimulation the late and prolonged C fibre evoked reflex nerve discharge (latency 160-200 ms, duration up to several hundred ms) was strongly depressed. Concomitantly, a short-lasting reflex nerve discharge appeared over the interval 115-160 ms. This released reflex nerve discharge (RR) had a constant latency. There was no simultaneous change of the A beta evoked reflex nerve discharge. After the end of the distant noxious stimulation the late C fibre evoked reflex nerve discharge (latency 160-200 ms) recovered. Concomitantly, the RR disappeared. The possibility that the class 2 neurons and the class 3 neurons are intercalated in different reflex pathways is discussed. PMID:3971178

  6. A robot conditioned reflex system modeled after the cerebellum.

    NASA Technical Reports Server (NTRS)

    Albus, J. S.

    1972-01-01

    Reduction of a theory of cerebellar function to computer software for the control of a mechanical manipulator. This reduction is achieved by considering the cerebellum, along with the higher-level brain centers which control it, as a type of finite-state machine with input entering the cerebellum via mossy fibers from the periphery and output from the cerebellum occurring via Purkinje cells. It is hypothesized that the cerebellum learns by an error-correction system similar to Perceptron training algorithms. An electromechanical model of the cerebellum is then developed for the control of a mechanical arm. The problem of modeling the granular layer which selects the set of parallel fibers which are active at any instant of time is considered, and a relevance matrix is constructed to model the relative degree of influence which mossy fibers from the various joints have on the sets of granule cells unique to each joint.

  7. Combined effects of preceding muscle vibration and contraction on the tonic vibration reflex

    Microsoft Academic Search

    Takayuki Nakajima; Masahiko Izumizaki; Chikara Sekihara; Takashi Atsumi; Ikuo Homma

    2009-01-01

    As a result of intrafusal thixotropy, muscle contraction at a short length followed by passive lengthening enhances the subsequent\\u000a tonic vibration reflex (TVR). We studied the effects of muscle vibration, contraction, and their combination on the subsequent\\u000a TVR in the left biceps in 20 healthy men. The preceding vibration (20 or 80 Hz) conditioning at a short or long length was

  8. Experimental muscle pain increases the human stretch reflex

    Microsoft Academic Search

    Dagfinn A Matre; Thomas Sinkjær; Peter Svensson; Lars Arendt-Nielsen

    1998-01-01

    In this study we investigated the effect of human experimental muscle pain on H- and stretch reflexes as indicators of changes in muscle spindle sensitivity. Fourteen healthy, male volunteers participated in the study. Muscle pain was produced by infusion of 5% hypertonic saline over a period of 10–15 min in m. soleus and in m. tibialis anterior. Reflexes were elicited

  9. Variable Patterned Pudendal Nerve Stimuli Improves Reflex Bladder Activation

    Microsoft Academic Search

    Tim M. Bruns; Narendra Bhadra; Kenneth J. Gustafson

    2008-01-01

    We evaluated variable patterns of pudendal nerve (PN) stimuli for reflex bladder excitation. Reflex activation of the bladder has been demonstrated previously with 20-33 Hz continuous stimulation of PN afferents. Neuronal circuits accessed by afferent mediated pathways may respond better to physiological patterned stimuli than continuous stimulation. Unilateral PN nerve cuffs were placed in neurologically intact male cats. PN stimulation

  10. Reflexive Management Learning: An Integrative Review and a Conceptual Typology

    ERIC Educational Resources Information Center

    Cotter, Richard J.; Cullen, John G.

    2012-01-01

    The scale and reach of the recent global financial has created a fresh wave of interest in exploring more sustainable forms of management. A central thrust behind this trend in the practice of management development and education has been the accentuation of reflexivity. There are many variations in how reflexivity is understood, and this article…

  11. Assessing European futures in an age of reflexive security

    Microsoft Academic Search

    Tom Vander Beken; Kristof Verfaillie

    2010-01-01

    Over the past decade, European assessments of organised crime have evolved into strategic future-oriented intelligence systems. Policy-makers want to be informed about coming organised crime threats and challenges. We use the concepts of reflexive government and reflexive security to explore this shift in EU policing, and suggest that strategic planning in the field of organised crime control might benefit from

  12. The proboscis extension reflex not elicited in Magachilid bees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Honey bees (Apis mellifera L.) will reflexively extend their proboscis in response to antennal stimulation with sucrose solution. For decades, the proboscis extension reflex (PER) of honey bees has been used as a tool to further the understanding of their cognitive processes, such as learning and m...

  13. The expiration reflex from the trachea and bronchi

    Microsoft Academic Search

    M. Tatar; J. Hanacek; J. Widdicombe

    2008-01-01

    The expiration reflex (ER) is a forced expiratory effort against a closed glottis that subsequently opens to eject laryngeal debris and prevent aspiration of material. It is distinct from the cough reflex. Its source is usually assumed to be restricted to the larynx and vocal folds, and its possible origin from the tracheobronchial (TB) tree has been suggested but never

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

    PubMed Central

    Murphy, Megan N.; Mizuno, Masaki; Mitchell, Jere H.

    2011-01-01

    Heart rate and blood pressure are elevated at the onset and throughout the duration of dynamic or static exercise. 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. Mechanically sensitive and metabolically sensitive receptors activating the exercise pressor reflex are located on the unencapsulated nerve terminals of group III and group IV afferent sensory neurons, respectively. Mechanoreceptors are stimulated by the physical distortion of their receptive fields during muscle contraction and can be sensitized by the production of metabolites generated by working skeletal myocytes. The chemical by-products of muscle contraction also stimulate metaboreceptors. Once activated, group III and IV sensory impulses are transmitted to cardiovascular control centers within the brain stem where they are integrated and processed. Activation of the reflex results in an increase in efferent sympathetic nerve activity and a withdrawal of parasympathetic nerve activity. These actions result in the precise alterations in cardiovascular hemodynamics requisite to meet the metabolic demands of working skeletal muscle. Coordinated activity by this reflex is altered after the development of cardiovascular disease, generating exaggerated increases in sympathetic nerve activity, blood pressure, heart rate, and vascular resistance. The basic components and operational characteristics of the reflex, the techniques used in human and animals to study the reflex, and the emerging evidence describing the dysfunction of the reflex with the advent of cardiovascular disease are highlighted in this review. PMID:21841019

  15. Diamond graphs and super-reflexivity William B. Johnson

    E-print Network

    Johnson, William B.

    Diamond graphs and super-reflexivity William B. Johnson and Gideon Schechtman Abstract The main result is that a Banach space X is not super-reflexive if and only if the diamond graphs Dn Lipschitz and Charikar proved that the diamond graphs Dn, which were known ([GNRS]) to Lipschitz embed into 1

  16. Bourdieu and Science Studies: Toward a Reflexive Sociology

    ERIC Educational Resources Information Center

    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…

  17. Felodipine, Blood Pressure, and Cardiovascular Reflexes in Hypertensive Humans

    Microsoft Academic Search

    STEPHEN A. SMITH; PETER J. E. MACE; WILLIAM A. LITTLER

    SUMMARY The influence of acute and chronic treatment with felodipine on ambulatory intra- arterial blood pressure, certain cardiac reflexes, and plasma renin activity was studied in nine patients with essential hypertension. Acute oral administration of the drug caused a significant reduction in blood pressure associated with an increase in heart rate mediated by the sinoaortic baroreceptor- heart rate reflex. After

  18. Approaches to Reflexivity: Navigating Educational and Career Pathways

    ERIC Educational Resources Information Center

    Dyke, Martin; Johnston, Brenda; Fuller, Alison

    2012-01-01

    This paper provides a critical appraisal of approaches to reflexivity in sociology. It uses data from social network research to argue that Archer's approach to reflexivity provides a valuable lens with which to understand how people navigate their education and career pathways. The paper is also critical of Archer's methodology and typology of…

  19. Iris Pigmentation and Fractionated Reaction and Reflex Time.

    ERIC Educational Resources Information Center

    Hale, Bruce D.; And Others

    Behavioral measures, fractionated reaction and reflex times by means of electromyography, were used to determine if the eye color differences are found in the central or peripheral regions of the nervous system. The purpose of this research was to determine the truth of the hypothesis that dark-eyed individuals have faster reflex and reaction time…

  20. Convergence in Reflex Pathways from Multiple Cutaneous Nerves Innervating the Foot Depends upon the Number of Rhythmically Active Limbs during Locomotion

    PubMed Central

    Nakajima, Tsuyoshi; Mezzarane, Rinaldo A.; Hundza, Sandra R.; Komiyama, Tomoyoshi; Zehr, E. Paul

    2014-01-01

    Neural output from the locomotor system for each arm and leg influences the spinal motoneuronal pools directly and indirectly through interneuronal (IN) reflex networks. While well documented in other species, less is known about the functions and features of convergence in common IN reflex system from cutaneous afferents innervating different foot regions during remote arm and leg movement in humans. The purpose of the present study was to use spatial facilitation to examine possible convergence in common reflex pathways during rhythmic locomotor limb movements. Cutaneous reflexes were evoked in ipsilateral tibialis anterior muscle by stimulating (in random order) the sural nerve (SUR), the distal tibial nerve (TIB), and combined simultaneous stimulation of both nerves (TIB&SUR). Reflexes were evoked while participants performed rhythmic stepping and arm swinging movement with both arms and the leg contralateral to stimulation (ARM&LEG), with just arm movement (ARM) and with just contralateral leg movement (LEG). Stimulation intensities were just below threshold for evoking early latency (<80 ms to peak) reflexes. For each stimulus condition, rectified EMG signals were averaged while participants held static contractions in the stationary (stimulated) leg. During ARM&LEG movement, amplitudes of cutaneous reflexes evoked by combined TIB&SUR stimulation were significantly larger than simple mathematical summation of the amplitudes evoked by SUR or TIB alone. Interestingly, this extra facilitation seen during combined nerve stimulation was significantly reduced when performing ARM or LEG compared to ARM&LEG. We conclude that locomotor rhythmic limb movement induces excitation of common IN reflex pathways from cutaneous afferents innervating different foot regions. Importantly, activity in this pathway is most facilitated during ARM&LEG movement. These results suggest that transmission in IN reflex pathways is weighted according to the number of limbs directly engaged in human locomotor activity and underscores the importance of arm swing to support neuronal excitability in leg muscles. PMID:25170606

  1. Airway reflexes, autonomic function, and cardiovascular responses.

    PubMed Central

    Widdicombe, J; Lee, L Y

    2001-01-01

    In this article, we review the cardiovascular responses to the inhalation of irritants and pollutants. Many sensory receptors in the respiratory system, from nose to alveoli, respond to these irritants and set up powerful reflex changes, including those in the cardiovascular system. Systemic hypotension or hypertension, pulmonary hypertension, bradycardia, tachycardia, and dysrhythmias have all been described previously. Most of the experiments have been acute and have been performed on anesthetized experimental animals. Experiments on humans suggest we have similar sensory systems and reflex responses. However, we must use caution when applying the animal results to humans. Most animal experiments, unlike those with humans, have been performed using general anesthesia, with irritants administered in high concentrations, and often to a restricted part of the respiratory tract. Species differences in the response to irritants are well established. We must be even more careful when applying the results of acute experiments in animals to the pathophysiologic changes observed in prolonged exposure to environmental pollution in humans. PMID:11544167

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed rest period, with a return to baseline 3 to 5 days after bed rest, depending on the duration of bed rest. In addition, a relationship between CV and loss of muscle strength in the lower leg was observed post bed rest for most subjects. Immediately post-bed rest, most subjects showed decreased performance on SOTs, with the greater decrements on sway-referenced support and head movement conditions. Post-bed rest decrements were less than typically observed following spaceflight. Decrements in postural control and the stretch reflex can be primarily attributed to the unloading mechanisms this ground-based analog provides. The stretch reflex is a concise test measurement that can be obtained during the head-down phase of bed rest, as it does not interfere with the bed rest paradigm. This makes it an ideal tool that can detect, early on, whether a countermeasure is successful in preserving muscle function.

  3. Effects of horizontal body casting on the baroreceptor reflex control of heart rate

    NASA Technical Reports Server (NTRS)

    Billman, G. E.; Dickey, D. T.; Sandler, H.; Stone, H. L.

    1982-01-01

    The purpose of this study was to investigate the effects of long-term horizontal body position on baroreceptor reflex control of heart rate. Six male rhesus monkeys (6.2-9.4 kg) were given bolus injections of 4.0 microgram/kg, phenylephrine during each of the following conditions: awake, anesthetized (10 mg/kg ketamine HCl), and after beta-blockade (1 mg/kg propranolol HCl) before, 7, 14, and 28 days after being placed in a horizontal body cast. R-R interval vs. systolic arterial pressure was plotted, and the slope was determined by least-squares-fit linear regression. Baroreceptor slope was significantly reduced by 7 days of horizontal body position and remained attenuated throughout the 28-day restraint period both before and after beta-receptor blockade. These data are consistent with the thesis that prolonged exposure to a zero-gravity environment impairs autonomic reflex regulation of the cardiovascular system.

  4. Potential enhancement of warm X-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A. [Sandia National Labs., Albuquerque, NM (United States); Cooperstein, G. [Naval Research Lab., Washington, DC (United States)] [and others

    1995-08-01

    The potential for generating intense bursts of warm x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions, for a Jupiter (60-MA, 5-MV, 100-ns) class accelerator. The calculations are compared with data from Gamble-II experiments and applied to two suggested Jupiter diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung, which accompanies the warm x rays, is a concern then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately}400 {mu}m for low-Z targets like aluminum and thinner than {approximately}5 {mu}m for high-Z targets like gold.

  5. Potential enhancement of warm x-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A. [Sandia National Labs., Albuquerque, NM (United States); Cooperstein, G.; Weber, B.V. [Naval Research Lab., Washington, DC (United States)

    1995-07-01

    The potential for generating intense bursts of war x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions. The calculation are compared with data from Gamble-II experiments and applied to two suggest Jupiter (60-MA, 5-MV, 100-ns) diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung which accompanies the warm x rays is a concern, then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately} 400 {mu}m for low-Z targets like aluminum and thinner than {approximately} 5 {mu}m for high-Z targets like gold.

  6. Sex differences in nociceptive withdrawal reflex and pain perception.

    PubMed

    Mylius, Veit; Kunz, Miriam; Schepelmann, Karsten; Lautenbacher, Stefan

    2005-09-01

    Experimentally induced pain often reveals sex differences, with higher pain sensitivity in females. The degree of differences has been shown to depend on the stimulation and assessment methods. Since sex differences in pain develop anywhere along the physiological and psychological components of the nociceptive system, we intended to compare the nociceptive flexion reflex (NFR) as a more physiological (spinal) aspect of pain procession to the verbal pain report of intensity and unpleasantness as the more psychological (cortical) aspect. Twenty female and twenty male healthy university students were investigated by use of nociceptive flexion reflex threshold (staircase method) after electrical stimulation of the N. suralis. Furthermore, we assessed supra-threshold reflex responses (latency, amplitude and area) by applying 10 stimuli 5 mA above reflex threshold. Following each stimulation, the subjects provided pain ratings of intensity and unpleasantness on a visual analogue scale. Females exhibited marked lower nociceptive flexion reflex thresholds than males, while the supra-threshold reflex response tailored to the individual reflex threshold did not show any significant differences. The verbal pain ratings, corrected for NFR threshold, were not found to differ significantly. The large sex differences in nociception that were present in NFR threshold but not in the pain ratings corroborate the hypothesis that spinal processes contribute substantially to sex differences in pain procession. PMID:16338828

  7. The sequelae of reflex sympathetic dystrophy.

    PubMed

    Zyluk, A

    2001-04-01

    This paper presents the results of a retrospective analysis of 94 patients who were assessed at a mean of 11 months after successful treatment of reflex sympathetic dystrophy (RSD) of the hand. Fifty-four percent still complained of pain related to the weather, and many complained of cold intolerance (44%), slight pain after use (34%), nail and hair growth changes (34%), sensory disturbances (34%) and stiffness of fingers in the morning (28%). There were also complaints of reduced finger extension, pain and loss of movement in the shoulder joint and hand swelling after use, and 78% of patients had significantly reduced grip strength. These results suggest that, in spite of resolution of the acute RSD problem, significant long term sequelae of RSD continue to impair function of the hand in a proportion of patients. PMID:11281669

  8. Plasticity of bladder reflex pathways during postnatal development.

    PubMed

    de Groat, William C

    2002-12-01

    Neuroanatomical and electrophysiological techniques have provided insights into the organization of the spinal cord circuitry and the neurotransmitter mechanisms involved in primitive voiding reflexes in neonatal animals. Patch clamp studies of unitary synaptic transmission in spinal cord slice preparations indicate that developmental plasticity in sacral parasympathetic reflex pathways is due in part to alterations in the glutamatergic excitatory transmission between interneurons and parasympathetic preganglionic neurons. It is proposed that these synaptic changes are due to competition between segmental and supraspinal inputs. Thus, synaptic remodeling in the sacral parasympathetic nucleus is likely to be an important factor in the postnatal maturation of voiding reflexes. PMID:12527020

  9. Postauricular and Superior Auricular Reflex Modulation during Emotional Pictures and Sounds

    PubMed Central

    Benning, Stephen D.

    2010-01-01

    The postauricular reflex is a relatively new psychophysiological measure of appetitive emotional processing during picture viewing. However, the degree to which other auricular (i.e., superior and anterior auricular) muscles might exhibit reflexive activity congruent with that found in the postauricular muscle has not been investigated, nor has the robustness of postauricular reflex modulation across stimulus modality. In this study, postauricular reflexes were the only reflexes that showed consistent emotional modulation across ears and genders. Additionally, postauricular reflexes were significantly modulated for both emotional pictures and sounds; in both cases, postauricular reflexes were greatest during pleasant stimuli. PMID:20636290

  10. Nasocardiac reflex during aspiration and injection through a nasogastric tube: An infrequent occurrence

    PubMed Central

    Haldar, Rudrashish; Kaur, Jasleen; Bajwa, Sukhminder Jit Singh

    2015-01-01

    Nasocardiac reflex is a relatively less discussed variant of trigeminovagal reflex where the afferent arc of the reflex is represented by any of the branches of the trigeminal nerves, and the efferent arc is via the vagus nerve. Elicitation of this reflex is commonly seen during surgical manipulation and is manifested as bradycardia or even asystole. We report a case where nasocardiac reflex was unusually observed in a patient when aspiration and injection were done through a nasogastric tube. PMID:25878434

  11. Control of Bipedal Walking Exploiting Postural Reflexes and Passive Dynamics

    E-print Network

    Berns, Karsten

    Control of Bipedal Walking Exploiting Postural Reflexes and Passive Dynamics Tobias Luksch biology to walking machines. Examples include the exploitation of passive dynamics and elasticities [6 lacking in efficiency, velocity, and robustness. Thus, a control concept for dynamic walking based

  12. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered...

  13. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered...

  14. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered...

  15. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered...

  16. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered...

  17. REFLEX MODIFICATION AND THE ASSESSMENT OF SENSORY DYSFUNCTION

    EPA Science Inventory

    In summary, reflex modification of the startle response is a technique that can provide rapid, objective, and quantitative assessments of sensorimotor function. dvantages of this technique involve the ability to test animals rapidly, test without prior training, test without util...

  18. Reconsidering reflexivity: introducing the case for intellectual entrepreneurship.

    PubMed

    Cutcliffe, John R

    2003-01-01

    In this article, the author reconsiders reflexivity and attempts to examine some unresolved issues by drawing particular attention to the relationship between reflexivity and certain related phenomena/processes: the researcher's a priori knowledge, values, beliefs; empathy within qualitative research; the presence and influence of the researcher's tacit knowledge, and May's "magic" in method. Given the limitations of some reflexive activity identified in this article, the author introduces the case for greater intellectual entrepreneurship within the context of qualitative research. He suggests that excessive emphasis on reflexive activity might inhibit intellectual entrepreneurship. Wherein intellectual entrepreneurship implies a conscious and deliberate attempt on the part of academics to explore the world of ideas boldly; to take more risks in theory development and to move away from being timid researchers. PMID:12564268

  19. Reflexive research ethics in fetal tissue xenotransplantation research.

    PubMed

    Panikkar, Bindu; Smith, Natasha; Brown, Phil

    2012-01-01

    For biomedical research in which the only involvement of the human subject is the provision of tissue or organ samples, a blanket consent, i.e., consent to use the tissue for anything researchers wish to do, is considered by many to be adequate for legal and Institutional Review Board (IRB) requirements. Alternatively, a detailed informed consent provides patients or study participants with more thorough information about the research topic. We document here the beliefs and opinions of the research staff on informed consent and the discussion-based reflexive research ethics process that we employed in our fetal tissue xenotransplantion research on the impact of environmental exposures on fetal development. Reflexive research ethics entails the continued adjustment of research practice according to relational and reflexive understandings of what might be beneficent or harmful. Such reflexivity is not solely an individual endeavor, but rather a collective relationship between all actors in the research process. PMID:23074992

  20. Non-reflexive Logical Foundation for Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    da Costa, N. C. A.; de Ronde, C.

    2014-12-01

    On the one hand, non-reflexive logics are logics in which the principle of identity does not hold in general. On the other hand, quantum mechanics has difficulties regarding the interpretation of `particles' and their identity, also known in the literature as `the problem of indistinguishable particles'. In this article, we will argue that non-reflexive logics can be a useful tool to account for such quantum indistinguishability. In particular, we will provide a particular non-reflexive logic that can help us to analyze and discuss this problem. From a more general physical perspective, we will also analyze the limits imposed by the orthodox quantum formalism to consider the existence of indistinguishable particles in the first place, and argue that non-reflexive logics can also help us to think beyond the limits of classical identity.

  1. Loudness changes resulting from an electrically induced middle-ear reflex.

    NASA Technical Reports Server (NTRS)

    Gunn, W. J.

    1973-01-01

    An experiment was conducted in order to determine the changes in loudness brought about by electro-cutaneous elicitation of the middle-ear reflex. Subjects were required to judge the relative loudness of the second of three consecutive 30-msec bursts of tone, the second tone being accompanied by an electrical shock to the external auditory meatus, capable of eliciting a contraction of the middle-ear muscles. The difference between these judgments and those of the control condition (shock on the arm) was taken to represent a measure of the attenuation provided by contraction of the middle-ear muscles. Test tones were 500, 1000, 2000, and 3000 Hz at levels of 65, 75, 85, 95, and 105 dB. The results indicate that the middle-ear reflex decreases the middle-ear's transmission mainly for low-frequency sounds. The results fail to lend support to the Loeb-Riopelle hypothesis that the middle-ear reflex acts as a limiter, rather than a linear attenuator.

  2. A cost minimisation and Bayesian inference model predicts startle reflex modulation across species

    PubMed Central

    Bach, Dominik R.

    2015-01-01

    In many species, rapid defensive reflexes are paramount to escaping acute danger. These reflexes are modulated by the state of the environment. This is exemplified in fear-potentiated startle, a more vigorous startle response during conditioned anticipation of an unrelated threatening event. Extant explanations of this phenomenon build on descriptive models of underlying psychological states, or neural processes. Yet, they fail to predict invigorated startle during reward anticipation and instructed attention, and do not explain why startle reflex modulation evolved. Here, we fill this lacuna by developing a normative cost minimisation model based on Bayesian optimality principles. This model predicts the observed pattern of startle modification by rewards, punishments, instructed attention, and several other states. Moreover, the mathematical formalism furnishes predictions that can be tested experimentally. Comparing the model with existing data suggests a specific neural implementation of the underlying computations which yields close approximations to the optimal solution under most circumstances. This analysis puts startle modification into the framework of Bayesian decision theory and predictive coding, and illustrates the importance of an adaptive perspective to interpret defensive behaviour across species. PMID:25660056

  3. The past, present, and future of health development campaigns: reflexivity and the critical-cultural approach.

    PubMed

    Dutta, Mohan Jyoti; de Souza, Rebecca

    2008-07-01

    In contemporary society, health issues have gained increasing urgency in both political and academic spheres. Looking back at the failure of the modernist development initiatives, there is the need to realize that we live in a time of increasing sociopolitical complexity. The present moment is perhaps best understood in terms of a complex tension and linkage between the past and present, global and local, modern and postmodern. The critical-cultural approach to health campaigns is an approach that, through the reflexive interrogation of modernist assumptions underlying health communication campaigns, attempts to foreground the tensions inherent in the practice of health campaigns. This essay discusses the manner in which the critical-cultural approach interrogates modernist assumptions and provides an alternative paradigm for approaching the theory and practice of health campaigns by suggesting the necessity for reflexivity. Specifically, we discuss how the perspective interrogates the role of the media in development, the significance of culture, the locus of health responsibility, the impact of structural conditions, and the politics of knowledge, providing examples of campaigns that illustrate this reflexivity. PMID:18701997

  4. A cost minimisation and Bayesian inference model predicts startle reflex modulation across species.

    PubMed

    Bach, Dominik R

    2015-04-01

    In many species, rapid defensive reflexes are paramount to escaping acute danger. These reflexes are modulated by the state of the environment. This is exemplified in fear-potentiated startle, a more vigorous startle response during conditioned anticipation of an unrelated threatening event. Extant explanations of this phenomenon build on descriptive models of underlying psychological states, or neural processes. Yet, they fail to predict invigorated startle during reward anticipation and instructed attention, and do not explain why startle reflex modulation evolved. Here, we fill this lacuna by developing a normative cost minimisation model based on Bayesian optimality principles. This model predicts the observed pattern of startle modification by rewards, punishments, instructed attention, and several other states. Moreover, the mathematical formalism furnishes predictions that can be tested experimentally. Comparing the model with existing data suggests a specific neural implementation of the underlying computations which yields close approximations to the optimal solution under most circumstances. This analysis puts startle modification into the framework of Bayesian decision theory and predictive coding, and illustrates the importance of an adaptive perspective to interpret defensive behaviour across species. PMID:25660056

  5. Critical practice in nursing care: analysis, action and reflexivity.

    PubMed

    Timmins, F

    This article examines critical practice and its underlying principles: analysis, action and reflexivity. Critical analysis involves the examination of knowledge that underpins practice. Critical action requires nurses to assess their skills and identify potential gaps in need of professional development. Critical reflexivity is personal analysis that involves challenging personal beliefs and assumptions to improve professional and personal practice. Incorporating these aspects into nursing can benefit nursing practice. PMID:16786927

  6. Trigeminocardiac reflex in embolization of intracranial dural arteriovenous fistula.

    PubMed

    Lv, X; Li, Y; Lv, M; Liu, A; Zhang, J; Wu, Z

    2007-10-01

    We report a case of immediate reproducible and reflexive response of asystole upon stimulation of Onyx injection during embolization of a tentorial dural arteriovenous fistula in a 53-year-old man. Upon recognition of the reflexive relationship between Onyx injection and increased vagal tone, the patient was given anticholinergic in an effort to block cholinergic hyperactivity. After atropine was given, no further dysrhythmias occurred. PMID:17885228

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

    NASA Astrophysics Data System (ADS)

    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 increased in spinal cord injury and stroke patients by subject' voluntary movement.

  8. Effects of static flexion–relaxation on paraspinal reflex behavior

    Microsoft Academic Search

    Kevin P. Granata; Ellen Rogers; Kevin Moorhouse

    2005-01-01

    Background. Static trunk flexion working postures and disturbed trunk muscle reflexes are related to increased risk of low-back pain. Animal studies conclude that these factors may be related; passive tissue strain in spinal ligaments causes subsequent short-term changes in reflex. Although studies have documented changes in the myoelectric onset angle of flexion–relaxation following prolonged static flexion and cyclic flexion we

  9. Auditory Brainstem Circuits That Mediate the Middle Ear Muscle Reflex

    PubMed Central

    Mukerji, Sudeep; Windsor, Alanna Marie; Lee, Daniel J.

    2010-01-01

    The middle ear muscle (MEM) reflex is one of two major descending systems to the auditory periphery. There are two middle ear muscles (MEMs): the stapedius and the tensor tympani. In man, the stapedius contracts in response to intense low frequency acoustic stimuli, exerting forces perpendicular to the stapes superstructure, increasing middle ear impedance and attenuating the intensity of sound energy reaching the inner ear (cochlea). The tensor tympani is believed to contract in response to self-generated noise (chewing, swallowing) and nonauditory stimuli. The MEM reflex pathways begin with sound presented to the ear. Transduction of sound occurs in the cochlea, resulting in an action potential that is transmitted along the auditory nerve to the cochlear nucleus in the brainstem (the first relay station for all ascending sound information originating in the ear). Unknown interneurons in the ventral cochlear nucleus project either directly or indirectly to MEM motoneurons located elsewhere in the brainstem. Motoneurons provide efferent innervation to the MEMs. Although the ascending and descending limbs of these reflex pathways have been well characterized, the identity of the reflex interneurons is not known, as are the source of modulatory inputs to these pathways. The aim of this article is to (a) provide an overview of MEM reflex anatomy and physiology, (b) present new data on MEM reflex anatomy and physiology from our laboratory and others, and (c) describe the clinical implications of our research. PMID:20870664

  10. Operant Conditioning Instrumental Learning

    E-print Network

    Coulson, Seana

    on the behavior · Consequence that follows response influences how animal will behave in the future ­ Operant & Operant Conditioning Classical · Acquisition · Extinction · Spontaneous Recovery · Stimulus Generalization · Stimulus Associations · Based on reflexive behaviors Operant · Acquisition · Extinction · Spontaneous

  11. ["Reflex--in a strict sense". Ivan Michajlovic Secenov and the founding myths of the 'Russian reflex empire'].

    PubMed

    Wurm, Barbara

    2009-03-01

    This paper aims to reconstruct Ivan Michajlovik Secenov's impact on reflex theory by looking at the different narratives which constitute his specific position in the history of science, where he is considered the Russian founder of a purely materialist framing of consciousness and behaviour, the father figure of objective psychology, and the predecessor of the 'great' Ivan Pavlov. I argue that Secenov himself was very much aware of the symbolic significance of the term "reflex" and that the rhetorical strategies in his opus magnum, The Reflexes of the Brain (1863), deliberately enforce the precarious twofold potential of reflexological conceptions as psycho-physiological structures as well as social programs. Also within the cultural and political settings of the 19th and 20th century, Secenov's comprehensive and multifaceted research work in the field of nerve physiology was gradually reduced to a strong, ideologically interpretable message: "All movements bearing the name of voluntary in physiology are reflex in a strict sense". PMID:19824305

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

    PubMed

    Akçali, Didem; Ta?, Ayça; Cizmeci, Pelin; Oktar, Suna; Zinnuro?lu, Murat; Arslan, Emre; Köseo?lu, Hüseyin; Babacan, Avni

    2009-04-01

    Piriformis syndrome is a rare cause of hip and foot pain which may be due to sciatic nerve irritation because of anatomic abnormalities of sciatic nerve and piriformis muscle or herniated disc, facet syndrome, trochanteric bursit, sacroiliac joint dysfunction, endometriosis and other conditions where sciatic nerve is irritated. There has been no reflex sympathetic dystrophy (RSD) case presented due to piriformis syndrome before. A sixty-two-year-old female patient had right foot and hip pain (VNS: 8), redness and swelling in the foot since 15 days. Her history revealed long walks and travelling 3 weeks ago and sitting on the foot for a long time for a couple of days. Physical examination revealed painful hip movement, positive straight leg rise. Erythema and hyperalgesia was present in dorsum of the right foot. Right foot dorsiflexion was weak and hyperesthesia was found in right L4-5 dermatome. Medical treatment and ultrasound treatment to piriformis muscle was not effective. The patient was injected 40 mg triamcinolon and local anesthetic in right piriformis muscle under floroscopy by diagnosis of piriformis syndrome, neuropathic pain and RSD. Pain and hyperalgesia resolved and motor weakness was better. During follow-up right foot redness resolved and pain decreased (VNS: 1). In this case report, there was vascular, muscle and skeletal signs supporting RSD, which shows us the therapoetic effect of diagnostic piriformis injection. The patient history, physical examination and diagnostic tests were evaluated by a multidisciplinary team which contributed to the treatment. PMID:19562536

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

    NASA Technical Reports Server (NTRS)

    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.

  14. Hippocampal State-Dependent Behavioral Reflex to an Identical Sensory Input in Rats

    PubMed Central

    Tokuda, Keita; Nishikawa, Michimasa; Kawahara, Shigenori

    2014-01-01

    We examined the local field potential of the hippocampus to monitor brain states during a conditional discrimination task, in order to elucidate the relationship between ongoing brain states and a conditioned motor reflex. Five 10-week-old Wistar/ST male rats underwent a serial feature positive conditional discrimination task in eyeblink conditioning using a preceding light stimulus as a conditional cue for reinforced trials. In this task, a 2-s light stimulus signaled that the following 350-ms tone (conditioned stimulus) was reinforced with a co-terminating 100-ms periorbital electrical shock. The interval between the end of conditional cue and the onset of the conditioned stimulus was 4±1 s. The conditioned stimulus was not reinforced when the light was not presented. Animals successfully utilized the light stimulus as a conditional cue to drive differential responses to the identical conditioned stimulus. We found that presentation of the conditional cue elicited hippocampal theta oscillations, which persisted during the interval of conditional cue and the conditioned stimulus. Moreover, expression of the conditioned response to the tone (conditioned stimulus) was correlated with the appearance of theta oscillations immediately before the conditioned stimulus. These data support hippocampal involvement in the network underlying a conditional discrimination task in eyeblink conditioning. They also suggest that the preceding hippocampal activity can determine information processing of the tone stimulus in the cerebellum and its associated circuits. PMID:25397873

  15. Prediction of the haemodynamic response to tracheal intubation: comparison of laser-Doppler skin vasomotor reflex and pulse wave reflex

    Microsoft Academic Search

    M. Luginbiihl; F. Reichlin; G. H. Sigurdsson; A. M. Zbinden; S. Petersen-Felix

    Background. The laser-Doppler skin vasomotor reflex (SVmR) caused by tetanic stimulation of the ulnar nerve may be a test that can predict the haemodynamic response to tracheal intubation. A decrease in pulse wave amplitude (pulse wave reflex, PWR) may be an alternative index of this response. We compared the abilities of PWR and SVmR to predict the haemodynamic response to

  16. Determination of trigeminocardiac reflex during rhinoplasty.

    PubMed

    Yorgancilar, E; Gun, R; Yildirim, M; Bakir, S; Akkus, Z; Topcu, I

    2012-03-01

    In most rhinoplasty procedures, osteotomies are usually required. The osteotomy areas are innervated by sensory branches of the trigeminal nerve. The trigeminocardiac reflex (TCR) is clinically defined as the sudden onset of parasympathetic activity during stimulation of the trigeminal nerve. When an osteotomy is performed or external pressure is applied over the nasal bone, the infraorbital nerve may send signals via this nerve. The aim of this prospective study is to determine the blood pressure changes and occurrence of TCR during rhinoplasty. one hundred and eight patients were enrolled into the study. Lidocaine and adrenaline combination (LAC) was injected only into the left lateral osteotomy sites. All patients underwent median, right-side, then left-side lateral osteotomies and nasal pyramid infracture. The haemodynamic changes were recorded. A 10% or more decrease in the heart rate from baseline was considered a TCR. TCR was detected in nine patients following lateral osteotomies and nasal pyramid infracture procedures (8.3%). The authors determined that LAC injection prior to osteotomy did not prevent TCR. Manipulation at or near the infraorbital nerve during rhinoplasty may cause TCR, even if local anaesthetic infiltration is used. PMID:22240287

  17. Frequency dependence of vestibuloocular reflex thresholds

    PubMed Central

    Haburcakova, Csilla; Lewis, Richard F.

    2012-01-01

    How the brain processes signals in the presence of noise impacts much of behavioral neuroscience. Thresholds provide one way to assay noise. While perceptual thresholds have been widely investigated, vestibuloocular reflex (VOR) thresholds have seldom been studied and VOR threshold dynamics have never, to our knowledge, been reported. Therefore, we assessed VOR thresholds as a function of frequency. Specifically, we measured horizontal VOR thresholds evoked by yaw rotation in rhesus monkeys, using standard signal detection approaches like those used in earlier human vestibular perceptual threshold studies. We measured VOR thresholds ranging between 0.21 and 0.76°/s; the VOR thresholds increased slightly with frequency across the measured frequency range (0.2–3 Hz). These results do not mimic the frequency response of human perceptual thresholds that have been shown to increase substantially as frequency decreases below 0.5 Hz. These reported VOR threshold findings could indicate a qualitative difference between vestibular responses of humans and nonhuman primates, but a more likely explanation is an additional dynamic neural mechanism that does not influence the VOR but, rather, influences perceptual thresholds via a decision-making process included in direction recognition tasks. PMID:22072512

  18. Crossed reflex reversal during human locomotion.

    PubMed

    Gervasio, Sabata; Farina, Dario; Sinkjær, Thomas; Mrachacz-Kersting, Natalie

    2013-05-01

    During human walking, precise coordination between the two legs is required in order to react promptly to any sudden hazard that could threaten stability. The networks involved in this coordination are not yet completely known, but a direct spinal connection between soleus (SOL) muscles has recently been revealed. For this response to be functional, as previously suggested, we hypothesize that it will be accompanied by a reaction in synergistic muscles, such as gastrocnemius lateralis (GL), and that a reversal of the response would occur when an opposite reaction is required. In the present study, surface EMGs of contralateral SOL and GL were analyzed after tibial nerve (TN), sural nerve (SuN), and medial plantar nerve (MpN) stimulation during two tasks in which opposite reactions are functionally expected: normal walking (NW), just before ipsilateral heel strike, and hybrid walking (HW) (legs walking in opposite directions), at ipsilateral push off and contralateral touchdown. Early crossed facilitations were observed in the contralateral GL after TN stimulation during NW, and a reversal of such responses occurred during HW. These results underline the functional significance of short-latency crossed responses and represent the first evidence for short-latency reflex reversal in the contralateral limb for humans. Muscle afferents seem to mediate the response during NW, while during HW cutaneous afferents are likely involved. It is thus possible that different afferents mediate the crossed response during different tasks. PMID:23427302

  19. Vestibuloocular reflex of rhesus monkeys after spaceflight

    NASA Technical Reports Server (NTRS)

    Cohen, Bernard; Kozlovskaia, Inessa; Raphan, Theodore; Solomon, David; Helwig, Denice; Cohen, Nathaniel; Sirota, Mikhail; Iakushin, Sergei

    1992-01-01

    The vestibuloocular reflex (VOR) of two rhesus monkeys was recorded before and after 14 days of spaceflight. The gain (eye velocity/head velocity) of the horizontal VOR, tested 15 and 18 h after landing, was approximately equal to preflight values. The dominant time constant of the animal tested 15 h after landing was equivalent to that before flight. During nystagmus induced by off-vertical axis rotation (OVAR), the latency, rising time constant, steady-state eye velocity, and phase of modulation in eye velocity and eye position with respect to head position were similar in both monkeys before and after flight. There were changes in the amplitude of modulation of horizontal eye velocity during steady-state OVAR and in the ability to discharge stored activity rapidly by tilting during postrotatory nystagmus (tilt dumping) after flight: OVAR modulations were larger, and tilt dumping was lost in the one animal tested on the day of landing and for several days thereafter. If the gain and time constant of the horizontal VOR exchange in microgravity, they must revert to normal soon after landing. The changes that were observed suggest that adaptation to microgravity had caused alterations in way that the central nervous system processes otolith input.

  20. Compensatory adrenal growth - A neurally mediated reflex

    NASA Technical Reports Server (NTRS)

    Dallman, M. F.; Engeland, W. C.; Shinsako, J.

    1976-01-01

    The responses of young rats to left adrenalectomy or left adrenal manipulation were compared to surgical sham adrenalectomy in which adrenals were observed but not touched. At 12 h right adrenal wet weight, dry weight, DNA, RNA, and protein content were increased (P less than 0.05) after the first two operations. Left adrenal manipulation resulted in increased right adrenal weight at 12 h but no change in left adrenal weight. Sequential manipulation of the left adrenal at time 0 and the right adrenal at 12 h resulted in an enlarged right adrenal at 12 h (P less than 0.01), and an enlarged left adrenal at 24 h (P less than 0.05), showing that the manipulated gland was capable of response. Bilateral adrenal manipulation of the adrenal glands resulted in bilateral enlargement of 12 h (P less than 0.01). Taken together with previous results, these findings strongly suggest that compensatory adrenal growth is a neurally mediated reflex.

  1. Trigeminocardiac reflex. A clinical phenomenon or a new physiological entity?

    PubMed

    Schaller, B

    2004-06-01

    The trigemino-cardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. The sensory nerve endings of the trigeminal nerve send neuronal signals via the Gasserian ganglion to the sensory nucleus of the trigeminal nerve, forming the afferent pathway of the reflex arc. This afferent pathway continues along the short internuncial nerve fibers in the reticular formatio to connect with the efferent pathway in the motor nucleus of the vagus nerve. Clinically, the trigemino-cardiac reflex has been reported to occur during craniofacial surgery, balloon-compression rhizolysis of the trigeminal ganglion, and tumor resection in the cerebellopontine angle. Apart from the few clinical reports, the physiological function of this brainstem-reflex has not yet been fully explored. From experimental findings, it may be suggested that the trigemino-cardiac reflex represents an expression of a central neurogenic reflex leading to rapid cerebrovascular vasodilatation generated from excitation of oxygen-sensitive neurons in the rostral ventrolateral medulla oblongata. By this physiological response, the adjustments of the systemic and cerebral circulations are initiated to divert blood to the brain or to increase blood flow within it. As it is generally accepted that the diving reflex and ischemic tolerance appear to involve at least partially similar physiological mechanisms, the existence of such endogenous neuroprotective strategies may extend the actually known clinical appearance of the TCR and include the prevention of other potentially brain injury states as well. This may be in line with the suggestion that the TCR is a physiological, but not a pathophysiological entity. PMID:15311339

  2. Driving a car using reflexive fuzzy behaviors

    SciTech Connect

    Pin, F.G.; Watanabe, Y.

    1992-01-01

    Vehicle control in a-priori unknown, unpredictable, and dynamic environments requires many calculational and reasoning schemes to operate on the basis of very imprecise, incomplete, or unreliable data. For such systems, in which all the uncertainties can not be engineered away, approximate reasoning may provide an alternative to the complexity and computational requirements of conventional uncertainty analysis and propagation techniques. Two types of computer boards including custom-designed VLSI chips have been developed to add a fuzzy inferencing capability to real-time control systems. All inferencing rules on a chip are processed in parallel, allowing execution of the entire rule base in about 30 [mu]sec, and therefore, making control of reflex-type'' of motions envisionable. The use of these boards and the approach using superposition of elemental sensor-based behaviors for the development of qualitative reasoning schemes emulating human-like navigation in a-prioii unknown environments are discussed. We describe how the human-like navigation scheme implemented on one of the qualitative inferencing boards was installed on a test-bed platform to investigate two control modes for driving a car in a-priori unknown environments on the basis of sparse and imprecise sensor data. In the first mode, the car navigates autonomously, while in the second mode, the system acts as a driver's aid providing the driver with linguistic (fuzzy) commands to turn left or right and speed up or slow down depending on the obstacles perceived by the sensors. Experiments with both modes of control are described in which the system uses only three acoustic range (sonar) sensor charmers to perceive the environment. Simulation results as well as indoor and outdoor experiments are discussed to illustrate the feasibility and robustness of autonomous navigation and/or safety enhancing driver's aid using the new fuzzy inferencing hardware system and some human-like reasoning schemes.

  3. Driving a car using reflexive fuzzy behaviors

    SciTech Connect

    Pin, F.G.; Watanabe, Y.

    1992-10-01

    Vehicle control in a-priori unknown, unpredictable, and dynamic environments requires many calculational and reasoning schemes to operate on the basis of very imprecise, incomplete, or unreliable data. For such systems, in which all the uncertainties can not be engineered away, approximate reasoning may provide an alternative to the complexity and computational requirements of conventional uncertainty analysis and propagation techniques. Two types of computer boards including custom-designed VLSI chips have been developed to add a fuzzy inferencing capability to real-time control systems. All inferencing rules on a chip are processed in parallel, allowing execution of the entire rule base in about 30 {mu}sec, and therefore, making control of ``reflex-type`` of motions envisionable. The use of these boards and the approach using superposition of elemental sensor-based behaviors for the development of qualitative reasoning schemes emulating human-like navigation in a-prioii unknown environments are discussed. We describe how the human-like navigation scheme implemented on one of the qualitative inferencing boards was installed on a test-bed platform to investigate two control modes for driving a car in a-priori unknown environments on the basis of sparse and imprecise sensor data. In the first mode, the car navigates autonomously, while in the second mode, the system acts as a driver`s aid providing the driver with linguistic (fuzzy) commands to turn left or right and speed up or slow down depending on the obstacles perceived by the sensors. Experiments with both modes of control are described in which the system uses only three acoustic range (sonar) sensor charmers to perceive the environment. Simulation results as well as indoor and outdoor experiments are discussed to illustrate the feasibility and robustness of autonomous navigation and/or safety enhancing driver`s aid using the new fuzzy inferencing hardware system and some human-like reasoning schemes.

  4. Aging attenuates the vestibulosympathetic reflex in humans

    NASA Technical Reports Server (NTRS)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    BACKGROUND: The vestibular system contributes to sympathetic activation by engagement of the otolith organs. However, there is a significant loss of vestibular function with aging. Therefore, the purpose of the present study was to determine if young and older individuals differ in their cardiovascular and sympathetic responses to otolithic stimulation (ie, head-down rotation, HDR). We hypothesized that responses to otolithic stimulation would be attenuated in older adults because of morphological and physiological alterations that occur in the vestibular system with aging. METHODS AND RESULTS: Arterial blood pressure, heart rate, muscle sympathetic nerve activity (MSNA), and head rotation were measured during HDR in 11 young (26 +/- 1 years) and 11 older (64 +/- 1 years) subjects in the prone posture. Five older subjects performed head rotation (chin to chest) in the lateral decubitus position, which simulates HDR but does not alter afferent inputs from the vestibular system. MSNA responses to HDR were significantly attenuated in older as compared with young subjects (P<0.01). MSNA increased in the older subjects by only 12 +/- 5% as compared with 85 +/- 16% in the young. Furthermore, HDR elicited significant reductions in mean arterial blood pressure in older (Delta-6 +/- 1 mm Hg; P<0.01) but not young subjects (Delta1 +/- 1 mm Hg). In contrast to HDR, head rotation performed in the lateral decubitus position did not elicit hypotension. MSNA responses to baroreceptor unloading and the cold pressor test were not different between the age groups. CONCLUSIONS: These data indicate that aging attenuates the vestibulosympathetic reflex in humans and may contribute to the increased prevalence of orthostatic hypotension with age.

  5. The blink reflex and the corneal reflex are followed by cortical activity resembling the nociceptive potentials induced by trigeminal laser stimulation in man.

    PubMed

    de Tommaso, M; Libro, G; Guido, M; Sciruicchio, V; Puca, F

    2001-09-01

    Laser stimulation of the supraorbital regions evokes brain potentials (LEPs) related to trigeminal nociception. The aim of this study was to record the R2 component of the blink reflex and the corneal reflex in 20 normal subjects, comparing the scalp activity following these reflexes with the nociceptive potentials evoked by CO2 laser stimulation of supraorbital regions. Cortical and muscular reflexes evoked by stimulation of the first trigeminal branch were recorded simultaneously. The R2 component of the blink reflex and the corneal reflex were followed by two cortical peaks, which resembled morphologically N-P waves of LEPs. The two peaks demonstrated a difference in latency of approximately 40 ms, which is consistent with activation time of nociception. This finding suggests that these reflexes are induced by activation of small pain-related fibers. PMID:11524152

  6. Decreased fibularis reflex response during inversion perturbations in FAI subjects.

    PubMed

    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<0.008). No significant differences in latency or amplitude reflex responses were identified between the two groups in the GM, ES, FIB_CLS, GM_CLS, or ES_CLS (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. PMID:24295544

  7. Plasticity of the human otolith-ocular reflex

    NASA Technical Reports Server (NTRS)

    Wall, C. 3rd; Smith, T. R.; Furman, J. M.

    1992-01-01

    The eye movement response to earth vertical axis rotation in the dark, a semicircular canal stimulus, can be altered by prior exposure to combined visual-vestibular stimuli. Such plasticity of the vestibulo-ocular reflex has not been described for earth horizontal axis rotation, a dynamic otolith stimulus. Twenty normal human subjects underwent one of two types of adaptation paradigms designed either to attenuate or enhance the gain of the semicircular canal-ocular reflex prior to undergoing otolith-ocular reflex testing with horizontal axis rotation. The adaptation paradigm paired a 0.2 Hz sinusoidal rotation about a vertical axis with a 0.2 Hz optokinetic stripe pattern that was deliberately mismatched in peak velocity. Pre- and post-adaptation horizontal axis rotations were at 60 degrees/s in the dark and produced a modulation in the slow component velocity of nystagmus having a frequency of 0.17 Hz due to putative stimulation of the otolith organs. Results showed that the magnitude of this modulation component response was altered in a manner similar to the alteration in semicircular canal-ocular responses. These results suggest that physiologic alteration of the vestibulo-ocular reflex using deliberately mismatched visual and semicircular canal stimuli induces changes in both canal-ocular and otolith-ocular responses. We postulate, therefore, that central nervous system pathways responsible for controlling the gains of canal-ocular and otolith-ocular reflexes are shared.

  8. Persistence of the nasotrigeminal reflex after pontomedullary transection

    PubMed Central

    Panneton, W. Michael; Gan, Qi; Sun, D. Wei

    2012-01-01

    Most behaviors have numerous components based on reflexes, but the neural circuits driving most reflexes rarely are documented. The nasotrigeminal reflex induced by stimulating the nasal mucosa causes an apnea, a bradycardia, and variable changes in mean arterial blood pressure (MABP). In this study we tested the nasotrigeminal reflex after transecting the brainstem at the pontomedullary junction. The nasal mucosae of anesthetized rats were stimulated with ammonia vapors and their brainstems then were transected. Complete transections alone induced an increase in resting heart rate (HR; p < 0.001) and MABP (p < 0.001), but no significant change in ventilation. However, the responses to nasal stimulation after transection were similar to those seen prior to transection. HR still dropped significantly (p < 0.001), duration of apnea remained the same, as did changes in MABP. Results from rats whose transection were incomplete are discussed. These data implicate that the neuronal circuitry driving the nasotrigeminal reflex, and indirectly the diving response, is intrinsic to the medulla and spinal cord. PMID:22154693

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

    PubMed Central

    Adediran, Samuel; Dhakarwal, Pradeep

    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 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. PMID:24765255

  10. Automated data reduction workflows for astronomy. The ESO Reflex environment

    NASA Astrophysics Data System (ADS)

    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 engine, the overall design choices and methods can also be applied to other environments for running automated science workflows.

  11. 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.

    PubMed

    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. PMID:12783170

  12. Startle reflex habituation in functional psychoses: a controlled study.

    PubMed

    Bolino, F; Manna, V; Di Cicco, L; Di Michele, V; Daneluzzo, E; Rossi, A; Casacchia, M

    1992-10-12

    The habituation of the startle reflex in a paradigm using electrical stimulation was studied in 17 psychotic patients and 18 healthy controls. The magnitude of the R2 component of the blink reflex differed between the groups (ANOVA, F = 5.81; P = 0.022) and during the course of trials (F = 25.72; P < 0.0001). Furthermore a statistically significant interaction of diagnosis x trials (F = 3.34; P = 0.022) emerged suggesting that an impairment in habituation of startle is present in patients but not in healthy controls despite a comparable reactivity. PMID:1465206

  13. Modulation of reflex responses in activated ankle dorsiflexors differs in healthy young and elderly subjects

    Microsoft Academic Search

    Malgorzata Klass; Stéphane Baudry; Jacques Duchateau

    During voluntary contractions, motor neurone activity is modulated by descending input and sensory feedback. Impaired excitatory\\u000a afferent feedback with ageing may, therefore, alter motor control. This study investigated the age-related changes in afferent\\u000a feedback through the recording of reflex responses during voluntary muscle activation. Short- and long-latency components\\u000a of the stretch reflex and Hoffmann reflex (H-reflex) were recorded during voluntary

  14. Hip angle induced modulation of H reflex amplitude, latency and duration in spinal cord injured humans

    E-print Network

    Abstract Objectives: To investigate the modulation of the soleus H reflex in spinal cord injured (SCI that imposing 108 of hip extension resulted in a significant facilitation in the size of the soleus H reflex. Keywords: Rehabilitation; Motor control; Muscle afferents; Paraplegia; Reflex modulation; Spasticity 1

  15. Facilitation and inhibition of jaw reflexes evoked by electrical stimulation of the cat's cerebral cortex

    Microsoft Academic Search

    K. Å. Olsson; S. Landgren

    1980-01-01

    The effects of electrical stimulation of the cerebral cortex on the monosynaptic jaw closing and the disynaptic jaw opening reflexes were studied in cats anaesthetized with chloralose. The time course of the reflex effects was recorded. Similar rhythmic sequences of facilitation and inhibition were observed in both reflexes (Fig. 3). The sequence could start with facilitation or inhibition. The latency

  16. Affective Modulation of the Startle Eyeblink and Postauricular Reflexes in Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    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…

  17. Noradrenergic Modulation of the Masseteric Reflex in Behaving Cats. I. Pharmacological Studies

    Microsoft Academic Search

    L. Stafford; Barry L. Jacobs

    The masseteric (jaw closure) reflex was utilized as a model system for assessing functional changes in central norepi- nephrine (NE) neurotransmission. This monosynaptic reflex was chosen because of its simple and well-defined circuitry, and because its motor component receives a dense NE in- nervation. Previous experiments in our laboratory described NE modulation of this reflex in the anesthetized rat. The

  18. The development of the pupillary light reflex and menace response in neonatal lambs and kids

    Microsoft Academic Search

    Afshin Raoofi; Pejman Mirfakhraie; Sorush Yourdkhani

    2011-01-01

    The aim of this study was to investigate the development of the pupillary light reflex and menace response in neonatal lambs and goat kids. Thirty lambs and 33 kids were assessed daily from birth until the pupillary light reflex and menace response had become established. All animals had a controlled pupillary light reflex within 20h of birth. Lambs and kids

  19. Reflex control of sympathetic outflow and depressed baroreflex sensitivity following myocardial infarction

    Microsoft Academic Search

    Christine M. Jones; M. Susan Quinn; Anthony J. Minisi

    2008-01-01

    Reflex control of heart rate is frequently impaired following myocardial infarction. This is referred to as depressed baroreflex sensitivity. The aim of these experiments was to assess the function of other autonomic reflexes in dogs with depressed baroreflex sensitivity. Comparisons were made to dogs in whom baroreflex sensitivity was preserved or unchanged after myocardial infarction. Under chloralose–barbiturate anesthesia, reflex control

  20. The Human Vertical Translation Vestibulo-ocular Reflex (tVOR): Normal and Abnormal Responses

    PubMed Central

    Liao, Ke; Walker, Mark F.; Joshi, Anand; Reschke, Millard; Strupp, Michael; Leigh, R. John

    2010-01-01

    Geometric considerations indicate that the human translational vestibulo-ocular reflex (tVOR) should have substantially different properties than the angular vestibulo-ocular reflex (aVOR). Specifically, tVOR cannot simultaneously stabilize images of distant and near objects on the retina. Most studies make the tacit assumption that tVOR acts to stabilize foveal images even though, in humans, tVOR is reported to compensate for less than 60% of foveal image motion. We have determined that the compensation gain (eye rotational velocity / required eye rotational velocity to maintain foveal target fixation) of tVOR is held steady at ~ 0.6 during viewing of either near or distant targets during vertical (bob) translations in ambient illumination. We postulate that tVOR evolved not to stabilize the image of the target on the fovea, but rather to minimize retinal image motion between objects lying in different depth planes, in order to optimize motion parallax information. Such behavior is optimized when binocular visual cues of both far and distant targets are available in ambient light. Patients with progressive supranuclear palsy or cerebellar ataxia show impaired ability to increase tVOR responses appropriately when they view near targets. In cerebellar patients, impaired ability to adjust tVOR responses to viewing conditions occurs despite intact ability to converge at near. Loss of the ability to adjust tVOR according to viewing conditions appears to represent a distinct disorder of vestibular function. PMID:19645882

  1. Studies of the horizontal vestibulo-ocular reflex on STS 7 and 8

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

    1988-01-01

    Unpaced voluntary horizontal head oscillation was used to study the Vestibulo-Ocular Reflex (VOR) on Shuttle flights STS 7 and 8. Ten subjects performed head oscillations at 0.33 Hz + or - 30 deg amplitude under the followng conditions: VVOR (visual VOR), eyes open and fixed on a stationary target; VOR-EC, with eyes closed and fixed on the same target in imagination; and VOR-S (VOR suppression), with eyes open and fixed on a head-synchronized target. Effects of weightlessness, flight phase, and Space Motion Sickness (SMS) on head oscillation characteristics were examined. A significant increase in head oscillation frequency was noted inflight in subjects free from SMS. In subjects susceptible to SMS, frequency was reduced during their Symptomatic period. The data also suggest that the amplitude and peak velocity of head oscillation were reduced early inflight. No significant changes were noted in reflex gain or phase in any of the test conditions; however, there was a suggestion of an increase in VVOR and VOR-ES gain early inflight in asymptomatic subjects. A significant difference in VOR-S was found between SMS susceptible and non-susceptible subjects. There is no evidence that any changes in VOR characteristics contributed to SMS.

  2. Light-dependent suppression of the vestibulo-ocular reflex during development.

    PubMed

    Sebastian, C; Horn, E

    1999-01-18

    In the fish Oreochromis mossambicus, light conditions affect the development of the roll-induced vestibuloocular reflex (rVOR). During development under continous light-dark conditions the rVOR amplitude, which is the maximum eye movement during a complete 360 degrees lateral roll, shows a secondary drop after a first peak at stage 17 by 64% (36.3 degrees at stage 17; 13.0 degrees at stage 20). This drop was shifted by 2 stages to older postembryonal stages and was 33% (29.2 degrees at stage 20; 19.5 degrees at stage 22) less pronounced in animals which were exposed to complete darkness for several days. Because the period of rVOR diminution is sensitive to light conditions, it is likely that outgrowing visual projection fibres reorganize the neuronal network underlying visual-vestibular behavior thus transiently suppressing the rVOR. PMID:10094157

  3. Cloacal reflexes and uptake of fluorescein-labeled polystyrene beads in broiler chickens.

    PubMed

    van der Sluis, H J; Dwars, R M; Vernooij, J C M; Landman, W J M

    2009-06-01

    Experiments were performed (1) to quantify reflex movements and volume uptake of physiological salt solution by the cloaca and (2) to evaluate the conditioned cloacal uptake of fluorescein-labeled polystyrene. In experiment 1, measurements were done on birds (n = 12) once a day at 3, 4, and 5 d of age and during 5 consecutive days at wk 3, 5, 7, and 9 of age. The reflexes and volume uptake after applying saline droplets were studied simultaneously during 30 s. The median number and range of reflexes per 30 s during the first week of age were 45 (28 to 54), at 3 wk 35 (18 to 52), at 5 wk 44 (27 to 60), at 7 wk 47 (32 to 61), and at 9 wk 44 (23 to 56). The median volume uptake and range in wk 1, 3, 5, 7, and 9 were 0.10 (0.05 to 0.30), 0.25 (0.05 to 0.60), 0.58 (0.25 to 1.15), 1.05 (0.50 to 2.25), and 1.15 (0.30 to 3.05) mL per 30 s, increasing significantly with time. In experiment 2, a solution containing 10(7) polystyrene beads/mL was applied to the cloaca of broilers (3 aged 2 wk and 3 aged 9 wk) during 30 s. Most beads were found in the bursa of Fabricius. In the bursal lumen, a median of 10(6.43) beads/mL was found; the median number found in the follicular tissue was 5 (range 3 to 38) beads per tissue section. In the lumen content of ileum, cecum, and rectum of all birds together, it was 10(5.87), 0, and 10(6.32) beads/ ml, respectively. Polystyrene beads were never found intramuraly. PMID:19439636

  4. L/N-type calcium channel blocker suppresses reflex aldosterone production induced by antihypertensive action.

    PubMed

    Aritomi, Shizuka; Konda, Tomoyuki; Yoshimura, Michihiro

    2012-07-01

    The L/N-type calcium channel blocker cilnidipine has been shown to suppress aldosterone production induced by angiotensin II (Ang II) in vitro. In addition, cilnidipine also suppresses the reflex tachycardia induced by its antihypertensive action in vivo. We investigated the effects of cilnidipine on the reflex aldosterone production induced by its antihypertensive action, to identify the differences in the effects of cilnidipine from those of the L-type calcium channel blocker nifedipine. Male SHR/Izm rats were anesthetized by intraperitoneal injection of pentobarbital sodium, and administered an intravenous infusion of saline supplemented or not with Ang II for 30 min. Blood pressure was monitored continuously in the femoral artery. Each of the calcium channel blockers under study was administered intravenously as a bolus through the femoral vein 1 min after the start of the Ang II infusion, and blood samples were collected 30 min after the start of the Ang II infusion. Following administration at nonhypotensive doses, all calcium channel blockers tended to decrease the plasma aldosterone. In particular, cilnidipine significantly suppressed the plasma aldosterone levels. On the other hand, under the condition of Ang II-induced hypertension, administration of a hypotensive dosage of cilnidipine showed no effect on the plasma aldosterone levels, whereas a hypotensive dosage of nifedipine significantly increased the plasma aldosterone levels. Our results suggest that the L/N-type calcium channel blocker cilnidipine reduces the plasma aldosterone level by suppressing the aldosterone production induced by reflex upregulation of the renin-angiotensin-aldosterone system associated with reduction of the blood pressure. PMID:21989861

  5. Oh Boy Comics! A Reflexive Ethnography of Comics and Childhood

    Microsoft Academic Search

    Vicky Grube

    2010-01-01

    This is a reflexive ethnography that interweaves a 1960s Midwest childhood with the culture of comic books and a critique of the 1960s and the nuclear family. My comic choices were more eclectic than my brother’s vast collection of Marvel, but both of us found in comics an escape from a strained childhood. The comic books, like all art, held

  6. Hindlimb venous distention evokes a pressor reflex in decerebrated rats

    PubMed Central

    Yamauchi, Katsuya; Stone, Audrey J.; Kaufman, Marc P.

    2014-01-01

    Abstract The distention of small vessels caused by an increase in blood flow to dynamically exercising muscles has been proposed as a stimulus that activates the thin fiber (groups III and IV) afferents evoking the exercise pressor reflex. This theory has been supported by evidence obtained from both humans and animals. In decerebrated unanesthetized rats with either freely perfused femoral arteries or arteries that were ligated 3 days before the experiment, we attempted to provide evidence in support of this theory by measuring arterial pressure, heart rate, and renal sympathetic nerve discharge while retrogradely injecting Ringer's solution in increasing volumes into the femoral vein just as it excited the triceps surae muscles. We found that the pressor response to injection was directly proportional to the volume injected. Retrograde injection of volumes up to and including 1 mL had no significant effect on either heart rate or renal sympathetic nerve activity. Cyclooxygenase blockade with indomethacin attenuated the reflex pressor response to retrograde injection in both groups of rats. In contrast, gadolinium, which blocks mechanogated channels, attenuated the reflex pressor response to retrograde injection in the “ligated rats,” but had no effect on the response in “freely perfused” rats. Our findings are consistent with the possibility that distension of small vessels within exercising skeletal muscle can serve as a stimulus to the thin fiber afferents evoking the exercise pressor reflex. PMID:24907299

  7. Postural reflexes in Parkinson's disease during ‘resist’ and ‘yield’ tasks

    Microsoft Academic Search

    Bastiaan R. Bloem; Dennis J. Beckley; Michael P. Remler; Raymund A. C. Roos; J. Gert van Dijk

    1995-01-01

    Postural reflexes in leg muscles appear to be set at a fixed gain in Parkinson's disease. To further investigate gain adaptation, we instructed 16 patients with idiopathic Parkinson's disease (studied during the ‘off’ phase) and 21 healthy controls to either ‘resist’ or ‘yield’ in response to 20 serial 4 ° toe-up perturbations of a supporting platform on which they were

  8. Practicing Reflexivity in the Study of Italian Migrants in London

    ERIC Educational Resources Information Center

    Seganti, Francesca Romana

    2010-01-01

    This article discusses the centrality of reflexivity in qualitative research through examples from my study on the role new media play in the lives of Italians in London. My hypothesis was that Italians were "in transit" in London and they were using new media to build "temporary" communities. I conducted in-depth interviews with members of the…

  9. Spinal reflex properties in the long term after stroke.

    PubMed

    Groenewegen, Jan S; de Groot, Jurriaan H; Schouten, Alfred C; Maier, Andrea B; Arendzen, J Hans; Meskers, Carel G M

    2012-04-01

    In the long term after stroke, secondary functional deterioration may be observed while patients also get older. Possible underlying mechanisms are largely unknown. We aimed to assess neuromuscular degeneration represented by alterations in peripheral reflex loop characteristics as a function of follow-up time after stroke, controlled for age. Twenty-one stroke survivors within a small age range (62-67 years) but large variance in follow-up time after stroke (1-15 years) and both five age matched (59-62 years) and young subjects (28-36 years) participated. Short and long latency reflexes evoked by ramp and hold stretches were identified from EMG traces of the m. flexor carpi radialis. Short latency reflex onset time was not enhanced (mean difference 1.6ms compared to age matched controls) and did not relate to follow-up time after stroke (p=0.81). Young controls showed significantly lower reflex delay times (mean difference 7.2ms with respect to older subjects, p=0.009). No evidence was found for peripheral neuromuscular deterioration as a function of follow up time after stroke. Functional deterioration as a result of ageing of stroke patients that may interact with post stroke follow-up time is of further interest. PMID:22196888

  10. Interface? What interface? Reflexivity in linguistics research in multicultural classrooms

    Microsoft Academic Search

    RICHARD BARWELL

    In this paper, I want to consider the interface between linguistic ethnography and education, where that interface is represented by the relationship between the researcher and their classroom data. In particular, I want to argue that this relationship is complex: the interface is very blurred. The key issue I want to consider is that of reflexivity, which, I will argue,

  11. Enhancing the Reflexivity of System Innovation Projects with System Analyses

    ERIC Educational Resources Information Center

    van Mierlo, Barbara; Arkesteijn, Marlen; Leeuwis, Cees

    2010-01-01

    Networks aiming for fundamental changes bring together a variety of actors who are part and parcel of a problematic context. These system innovation projects need to be accompanied by a monitoring and evaluation approach that supports and maintains reflexivity to be able to deal with uncertainties and conflicts while challenging current practices…

  12. Affective modulation of the startle reflex following traumatic brain injury

    Microsoft Academic Search

    Claire Williams; Rodger L. Wood

    2012-01-01

    Diminished emotional recognition, expression, and responsivity are frequent legacies of traumatic brain injury (TBI) that can have an adverse impact on relationships and psychosocial recovery. However, assessment of emotion responsivity is often difficult because many patients lack insight into their altered personality. To overcome this obstacle, we used a physiological measure of emotion responsivity, the startle reflex, to examine how

  13. Intra-abdominal Pressures during Voluntary and Reflex Cough

    Microsoft Academic Search

    W Robert Addington; Robert E Stephens; Michael M Phelipa; John G Widdicombe; Robin R Ockey

    2008-01-01

    BACKGROUND: Involuntary coughing such as that evoked from the larynx, the laryngeal cough reflex (LCR), triggers a coordinated contraction of the thoracic, abdominal and pelvic muscles, which increases intra-abdominal pressure (IAP), displaces the diaphragm upwards and generates the expiratory force for cough and airway clearance. Changes in the IAP during voluntary cough (VC) and the LCR can be measured via

  14. Conducting Systematic Review in Education: A Reflexive Narrative

    ERIC Educational Resources Information Center

    Nind, Melanie

    2006-01-01

    The evaluation of systematic review as part of the evidence-based or evidence-informed practice movement is a dominant theme in current debates in educational research. This article contributes to the debate by offering a personal, reflexive narrative on the process of doing systematic review, relating some of the arguments regarding the merits…

  15. Ontogeny of Infantile Oral Reflexes and Emerging Chewing.

    ERIC Educational Resources Information Center

    Sheppard, Justine Joan; Mysak, Edward D.

    1984-01-01

    To document movement patterns and to examine developmental interrelationships, the ontogeny of rooting, lip, lateral tongue, mouth opening, biting, and Babkin reflexes and the development of emerging chewing behaviors were observed in two normal infants over a period from 1 week to 35 weeks of age. (Author/RH)

  16. The reflex-diode HPM source on Aurora

    Microsoft Academic Search

    G. A. Huttlin; M. S. Bushell; D. B. Conrad; D. P. Davis; K. L. Ebersole; D. C. Judy; P. A. Lezcano; M. S. Litz; N. R. Pereira; B. G. Ruth; D. M. Weidenheimer; F. J. Agee

    1990-01-01

    The most recent in a series of experiments to develop the reflex diode as a source of microwaves on the Aurora relativistic electron-beam pulser is described. An overall output has been achieved for radial extraction of ~400 J in microwave bursts from ~100 to 150 ns at frequencies below 1 GHz. The diagnostics for radial extraction have included directional couplers,

  17. The reflex-diode HPM source on Aurora

    Microsoft Academic Search

    George A. Huttlin; Michael S. Bushell; David B. Conrad; David P. Davis; Kevin L. Ebersole

    1990-01-01

    The most recent in a series of experiments to develop the reflex diode as a source of microwaves on the Aurora relativistic electron-beam pulser is described. An overall output has been achieved for radial extraction of about 400 J in microwave bursts from about 100 to 150 ns at frequencies below 1 GHz. The diagnostics for radial extraction have included

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

    Microsoft Academic Search

    Scott A. Smith; Maurice A. Williams; Anna K. Leal; J ere H. Mitchell; Mary G. Garry

    2006-01-01

    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

  19. Electrocutaneous reflexes and multimodality evoked potentials in multiple sclerosis

    Microsoft Academic Search

    W G Friedli; P Fuhr

    1990-01-01

    Electrical stimulation of the digital nerves of the index finger produces changes in the EMG signal during steady voluntary contraction of the first dorsal interosseous muscle. This electrocutaneous reflex (ECR) was studied in 90 patients classified into different categories according to diagnostic criteria for multiple sclerosis. In addition, pattern reversal visual evoked responses (VER), brainstem auditory evoked responses (BAER) as

  20. Teaching Reflexivity: Undoing or Reinscribing Habits of Gender?

    ERIC Educational Resources Information Center

    Bondi, Liz

    2009-01-01

    This paper outlines an approach used in a course designed to teach reflexivity as a research skill and explores what kind of gender intervention such teaching might constitute. Although inspired by feminist debates about the complex power dynamics of research relationships, the course in question does not focus specifically on gender issues.…

  1. Positioning Resumes and Cover Letters as Reflective-Reflexive Process

    ERIC Educational Resources Information Center

    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…

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

    NASA Technical Reports Server (NTRS)

    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 < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion.

  3. A new hypothesis of cause of syncope: trigeminocardiac reflex during extraction of teeth.

    PubMed

    Arakeri, Gururaj; Arali, Veena

    2010-02-01

    Transient Loss Of Consciousness (TLOC) or vasovagal syncope is well known phenomenon in dental/maxillofacial surgery. Despite considerable study of vasovagal syncope, its pathophysiology remains to be fully elucidated. After having encountered a case of trigeminocardiac reflex after extraction of maxillary first molar we observed and studied 400 extractions under local anesthesia to know the relation between trigeminocardiac reflex and syncope. We make hypothesis that trigeminocardiac reflex which is usually seen under general anesthesia when all sympathetic reflexes are blunted can also occur under local anesthesia during extractions of maxillary molars (dento-cardiac reflex) and mediate syncope. PMID:19815349

  4. A reflexive neural network for dynamic biped walking control.

    PubMed

    Geng, Tao; Porr, Bernd; Wörgötter, Florentin

    2006-05-01

    Biped walking remains a difficult problem, and robot models can greatly facilitate our understanding of the underlying biomechanical principles as well as their neuronal control. The goal of this study is to specifically demonstrate that stable biped walking can be achieved by combining the physical properties of the walking robot with a small, reflex-based neuronal network governed mainly by local sensor signals. Building on earlier work (Taga, 1995; Cruse, Kindermann, Schumm, Dean, & Schmitz, 1998), this study shows that human-like gaits emerge without specific position or trajectory control and that the walker is able to compensate small disturbances through its own dynamical properties. The reflexive controller used here has the following characteristics, which are different from earlier approaches: (1) Control is mainly local. Hence, it uses only two signals (anterior extreme angle and ground contact), which operate at the interjoint level. All other signals operate only at single joints. (2) Neither position control nor trajectory tracking control is used. Instead, the approximate nature of the local reflexes on each joint allows the robot mechanics itself (e.g., its passive dynamics) to contribute substantially to the overall gait trajectory computation. (3) The motor control scheme used in the local reflexes of our robot is more straightforward and has more biological plausibility than that of other robots, because the outputs of the motor neurons in our reflexive controller are directly driving the motors of the joints rather than working as references for position or velocity control. As a consequence, the neural controller and the robot mechanics are closely coupled as a neuromechanical system, and this study emphasizes that dynamically stable biped walking gaits emerge from the coupling between neural computation and physical computation. This is demonstrated by different walking experiments using a real robot as well as by a Poincaré map analysis applied on a model of the robot in order to assess its stability. PMID:16595061

  5. Vestibuloocular reflex signal modulation during voluntary and passive head movements.

    PubMed

    Roy, Jefferson E; Cullen, Kathleen E

    2002-05-01

    The vestibuloocular reflex (VOR) effectively stabilizes the visual world on the retina over the wide range of head movements generated during daily activities by producing an eye movement of equal and opposite amplitude to the motion of the head. Although an intact VOR is essential for stabilizing gaze during walking and running, it can be counterproductive during certain voluntary behaviors. For example, primates use rapid coordinated movements of the eyes and head (gaze shifts) to redirect the visual axis from one target of interest to another. During these self-generated head movements, a fully functional VOR would generate an eye-movement command in the direction opposite to that of the intended shift in gaze. Here, we have investigated how the VOR pathways process vestibular information across a wide range of behaviors in which head movements were either externally applied and/or self-generated and in which the gaze goal was systematically varied (i.e., stabilize vs. redirect). VOR interneurons [i.e., type I position-vestibular-pause (PVP) neurons] were characterized during head-restrained passive whole-body rotation, passive head-on-body rotation, active eye-head gaze shifts, active eye-head gaze pursuit, self-generated whole-body motion, and active head-on-body motion made while the monkey was passively rotated. We found that regardless of the stimulation condition, type I PVP neuron responses to head motion were comparable whenever the monkey stabilized its gaze. In contrast, whenever the monkey redirected its gaze, type I PVP neurons were significantly less responsive to head velocity. We also performed a comparable analysis of type II PVP neurons, which are likely to contribute indirectly to the VOR, and found that they generally behaved in a quantitatively similar manner. Thus our findings support the hypothesis that the activity of the VOR pathways is reduced "on-line" whenever the current behavioral goal is to redirect gaze. By characterizing neuronal responses during a variety of experimental conditions, we were also able to determine which inputs contribute to the differential processing of head-velocity information by PVP neurons. We show that neither neck proprioceptive inputs, an efference copy of neck motor commands nor the monkey's knowledge of its self-motion influence the activity of PVP neurons per se. Rather we propose that efference copies of oculomotor/gaze commands are responsible for the behaviorally dependent modulation of PVP neurons (and by extension for modulation of the status of the VOR) during gaze redirection. PMID:11976372

  6. Effect of sympathetic nervous system activation on the tonic vibration reflex in rabbit jaw closing muscles.

    PubMed Central

    Grassi, C; Deriu, F; Passatore, M

    1993-01-01

    1. In precollicular decerebrate rabbits we investigated the effect of sympathetic stimulation, at frequencies within the physiological range, on the tonic vibration reflex (TVR) elicited in jaw closing muscles by small amplitude vibrations applied to the mandible (15-50 microns, 150-180 Hz). The EMG activity was recorded bilaterally from masseter muscle and the force developed by the reflex was measured through an isometric transducer connected with the mandibular symphysis. 2. Unilateral stimulation of the peripheral stump of the cervical sympathetic by the TVR, and a marked decrease or disappearance of the ipsilateral EMG activity. No significant changes were detected in the EMG contralateral to the stimulated nerve. Bilateral CSN stimulation reduced by 60-90% the force reflexly produced by the jaw closing muscles and strongly decreased or suppressed EMG activity on both sides. This effect was often preceded by a transient TVR enhancement, very variable in amplitude and duration, which was concomitant with the modest increase in pulmonary ventilation induced by the sympathetic stimulation. 3. During bilateral CSN stimulation, an increase in the vibration amplitude by a factor of 1.5-2.5 was sufficient to restore the TVR reduced by sympathetic stimulation. 4. The depressant action exerted by sympathetic activation on the TVR is mediated by alpha-adrenergic receptors, since it was almost completely abolished by the I.V. administration of either phentolamine or prazosin, this last drug being a selective antagonist of alpha 1-adrenoceptors. The sympathetically induced decrease in the TVR was not mimicked by manoeuvres producing a large and sudden reduction or abolition of the blood flow to jaw muscles, such as unilateral or bilateral occlusion of the common carotid artery. 5. The effect of sympathetic stimulation was not significantly modified after denervation of the inferior dental arch and/or anaesthesia of the temporomandibular joint, i.e. after having reduced the afferent input from those receptors, potentially affected by CSN stimulation, which can elicit either a jaw opening reflex or a decrease in the activity of the jaw elevator muscle motoneurons. 6. These data suggest that, when the sympathetic nervous system is activated under physiological conditions, there is a marked depression of the stretch reflex which is independent of vasomotor changes and is probably due to a decrease in sensitivity of muscle spindle afferents. PMID:8271218

  7. Interlimb coupling from the arms to legs is differentially specified for populations of motor units comprising the compound H-reflex during "reduced" human locomotion.

    PubMed

    Mezzarane, Rinaldo A; Klimstra, Marc; Lewis, Allen; Hundza, Sandra R; Zehr, E Paul

    2011-01-01

    Recent experiments have identified neuromechanical interactions between the arms and legs during human locomotor movement. Previous work reported that during the rhythmic movement of all four limbs, the influence of the arms on reflex expression in the legs was superimposed on the dominant effect of the legs. This evidence was based upon studies using cutaneous and H-reflex modulation as indices of neuronal activity related to locomotion. The earlier H-reflex study was restricted to one phase of movement and to only a fixed H-reflex amplitude. Also, all four limbs were actively engaged in locomotor movement, and this led to the speculation that the effect from the arms could be underestimated by "swamping" of the conditioning during movement of the test limb. Work from the cat suggests that descending locomotor drive may be differentially specified for different motor unit populations in the hindlimb. Accordingly, details of interlimb coordination between the arms and legs in humans require further characterization and an examination of different populations of motor units as can be obtained from H-reflex recruitment curve (RC) parameters. Using modulation of H-reflex amplitudes across the entire ascending limb as neural probes for interlimb coupling, the present study evaluated the separated influences of rhythmic activity of the arms and leg on neuronal excitability of a stationary "test leg". This three-limb "reduced" locomotion approach was applied using a stepping ergometer during the performance of three rhythmic movement tasks: arms (A); contralateral leg (L); and arms and contralateral leg (AL). Data were sampled at four different phases of the stepping cycle (using the moving leg as reference): start power (SP); end power (EP); start recovery (SR); and end recovery (ER). The main result was a large and significant influence of rhythmic AL activity on RC parameters of the H-reflex at EP and SP phases. However, the parameters (and thus motor unit populations) were differentially affected at each phase and task. For instance, a significant contribution of arms movement was noticed for H (max) (largest motor units) at EP phase (P < 0.05), but no changes was observed for other parameters related to lower reflex amplitude (e.g., H-reflex evoked with an input that elicited 50% of maximum reflex response during static condition; H@50%). On the other hand, at SR phase, the parameter H@50% was significantly affected during AL compared to L. It is suggested that the remote effect from arms rhythmic activity has been differentially manifested across motor unit populations for each phase of movement. These findings provide definitive evidence for interlimb coupling between cervical and lumbar oscillators in gating the excitability of reflex pathways to a leg muscle for different populations of motorneurons within the pool. This further supports the contention of similar functional organization for locomotor networks in the human when compared to other animals. Additionally, these data provide additional confirmation of the significant role of the output of neural control for rhythmic arm movement in modulating reflex excitability of the legs that is specifically adjusted according to the phase and task. PMID:21063693

  8. An electrophysiological study of somatic and visceral convergence in the reflex control of the external sphincters.

    PubMed

    McMahon, S B; Morrison, J F; Spillane, K

    1982-07-01

    1. Mass wave and single unit discharges have been recorded from pudendal efferents innervating the external anal and urethral sphincters in chloralose anaesthetized or decerebrate cats.2. Reflex discharges in these neurones were elicited by electrical stimulation of the contralateral pudendal nerve, the posterior cutaneous nerve of thigh, or the vesical or colonic branches of the pelvic nerve. The latencies of the evoked responses were 5.5-20 msec. The vesical branches of the pelvic nerve produced discharges less consistently than the other nerves.3. Irrespective of whether afferent stimulation produced an early evoked response there was always a prolonged period of depression of pudendal nerve excitability following the stimulus. Condition-test interactions showed that this depression began within 50 msec of the stimulus and that its duration varied between 150 and 2500 msec in single units, with a modal value of 500 msec.4. No evoked response or depression of excitability was seen when afferents in the hypogastric or lumbar colonic nerves were stimulated.5. Increasing intravesical or intracolonic pressure, within physiological limits, produced a graded reduction in the size of evoked discharges.6. Short trains of stimuli (four shocks in 20 msec) applied to the raphé nucleus, were capable of inhibiting test responses in pudendal efferents for periods of up to 800 msec.7. The possible functional roles of two groups of sphincteric reflex interneurones, with either excitatory or inhibitory receptive fields, are discussed. PMID:7131318

  9. Effects of Visual Cortex Activation on the Nociceptive Blink Reflex in Healthy Subjects

    PubMed Central

    Sava, Simona L.; de Pasqua, Victor; Magis, Delphine; Schoenen, Jean

    2014-01-01

    Bright light can cause excessive visual discomfort, referred to as photophobia. The precise mechanisms linking luminance to the trigeminal nociceptive system supposed to mediate this discomfort are not known. To address this issue in healthy human subjects we modulated differentially visual cortex activity by repetitive transcranial magnetic stimulation (rTMS) or flash light stimulation, and studied the effect on supraorbital pain thresholds and the nociceptive-specific blink reflex (nBR). Low frequency rTMS that inhibits the underlying cortex, significantly decreased pain thresholds, increased the 1st nBR block ipsi- and contralaterally and potentiated habituation contralaterally. After high frequency or sham rTMS over the visual cortex, and rMS over the right greater occipital nerve we found no significant change. By contrast, excitatory flash light stimulation increased pain thresholds, decreased the 1st nBR block of ipsi- and contralaterally and increased habituation contralaterally. Our data demonstrate in healthy subjects a functional relation between the visual cortex and the trigeminal nociceptive system, as assessed by the nociceptive blink reflex. The results argue in favour of a top-down inhibitory pathway from the visual areas to trigemino-cervical nociceptors. We postulate that in normal conditions this visuo-trigeminal inhibitory pathway may avoid disturbance of vision by too frequent blinking and that hypoactivity of the visual cortex for pathological reasons may promote headache and photophobia. PMID:24936654

  10. Effect of viral upper respiratory tract infection on cough reflex sensitivity

    PubMed Central

    2014-01-01

    Acute viral upper respiratory tract infection (URI; common cold) is among the most common medical conditions affecting man, with cough being a typical feature of the associated syndrome. Studies employing capsaicin inhalation challenge to measure cough reflex sensitivity have demonstrated a transient tussive hyperresponsiveness induced by URI that reverts to normal by 4-8 weeks post infection. Mechanisms proposed to explain the induction of cough by URI include a number of infection-associated airway effects, such as enhanced release of cytokines, neurotransmitters, and leukotrienes; increased neural receptor levels; reduced activity of neutral endopeptidases; transient modulation of afferent neural activity; mucus hypersecretion; and, possibly, effects on cholinergic motor pathways. Recent studies evaluating urge-to-cough (UTC), the sensation of irritation preceding the motor act of coughing, have demonstrated that URI induces a transient enhancement of UTC analogous to the effect observed on cough reflex sensitivity. The recently introduced concept of the Cough Hypersensitivity Syndrome may provide an explanation for the commonly observed clinical phenomenon of acute viral URI triggering what will develop into chronic, refractory cough in a subgroup of patients. PMID:25383204

  11. 'Diving reflex' in man - Its relation to isometric and dynamic exercise.

    NASA Technical Reports Server (NTRS)

    Bergman, S. A., Jr.; Campbell, J. K.; Wildenthal, K.

    1972-01-01

    To test the influence of physical activity on the diving reflex, 10 normal men held their breath with their faces immersed in 15 C water during rest, bicycle exercise, and sustained isometric handgrip contraction. At all conditions, a slight but statistically significant elevation of blood pressure and a marked decrease in heart rate occurred during each dive. During moderate bicycle exercise heart rate fell more rapidly than at rest and the final level of bradycardia approached that achieved at rest, despite the fact that predive heart rates were much higher during exercise. When diving occurred in combination with isometric exercise, bradycardia was less severe than during resting dives and final heart rates could be represented as the sum of the expected responses to each intervention alone. In all conditions apnea without face immersion caused bradycardia that was less severe than during wet dives.

  12. Effect of Systemic Alcohol and Nicotine on Airway Protective Reflexes

    PubMed Central

    Dua, Kulwinder S.; Surapaneni, Sri Naveen; Santharam, Rajesh; Knuff, David; Hofmann, Candy; Shaker, Reza

    2014-01-01

    OBJECTIVES Injection of water into the pharynx induces contraction of the upper esophageal sphincter (UES), triggers the pharyngo-UES contractile reflex (PUCR), and at a higher volume, triggers an irrepressible swallow, the reflexive pharyngeal swallow (RPS). These aerodigestive reflexes have been proposed to reduce the risks of aspiration. Alcohol ingestion can predispose to aspiration and previous studies have shown that cigarette smoking can adversely affect these reflexes. It is not known whether this is a local effect of smoking on the pharynx or a systemic effect of nicotine. The aim of this study was to elucidate the effect of systemic alcohol and nicotine on PUCR and RPS. METHODS Ten healthy non-smoking subjects (8 men, 2 women; mean age: 32±3 s.d. years) and 10 healthy chronic smokers (7 men, 3 women; 34±8 years) with no history of alcohol abuse were studied. Using previously described techniques, the above reflexes were elicited by rapid and slow water injections into the pharynx, before and after an intravenous injection of 5% alcohol (breath alcohol level of 0.1%), before and after smoking, and before and after a nicotine patch was applied. Blood nicotine levels were measured. RESULTS During rapid and slow water injections, alcohol significantly increased the threshold volume (ml) to trigger PUCR and RPS (rapid: PUCR: baseline 0.2±0.05, alcohol 0.4±0.09; P=0.022; RPS: baseline 0.5±0.17, alcohol 0.8±0.19; P=0.01, slow: PUCR: baseline 0.2±0.03, alcohol 0.4±0.08; P=0.012; RPS: baseline 3.0±0.3, alcohol 4.6±0.5; P=0.028). During rapid water injections, acute smoking increased the threshold volume to trigger PUCR and RPS (PUCR: baseline 0.4±0.06, smoking 0.67±0.09; P=0.03; RPS: baseline 0.7±0.03, smoking 1.1±0.1; P=0.001). No similar increases were noted after a nicotine patch was applied. CONCLUSIONS Acute systemic alcohol exposure inhibits the elicitation PUCR and RPS. Unlike cigarette smoking, systemic nicotine does not alter the elicitation of these reflexes. PMID:19550414

  13. Early Modern ET, Reflexive Telescopics, and Their Relevance Today

    NASA Astrophysics Data System (ADS)

    Danielson, Dennis

    The period from the discovery of Tycho's New Star in 1572 to Galileo's "geometrization of astronomical space" in 1610 (and the years following) saw the disintegration of the boundary between the sublunary and superlunary spheres—between the "lower storey" and "upper storey" of the Aristotelian Universe. This establishment of a strong physical affinity between the universe "up there" and the earthly realm "down here" was also complemented by the rise of Copernicanism: for once the Earth was seen as a planet, the other planets could readily be imagined as other Earths. This analogy suggested not only physical but also biological affinities and supported the plausibility of humans' capacity to travel to the Moon and beyond. Robert Burton—given the demise of Aristotle's physics—declared in 1621 that "If the heavens be penetrable … it were not amiss in this aerial progress to make wings and fly up." John Wilkins and Francis Godwin in the 1630s actively imagined creatures in the Moon and human journeys thither. The epic poet John Milton in 1667 hinted that "every star [is] perhaps a world / Of destined habitation." Moreover, space travel was no one-way street: Thomas Traherne in the 1670s imagined a dweller among the stars visiting Earth and remarking on what must be the condition of its inhabitants. In these and other ways, seventeenth-century writers offered serious and impressive speculation about extraterrestrial life and its possible perceptions of Earth. Such speculations remain pertinent to astrobiological theory today. What Hans Blumenberg in the 1970s called "reflexive telescopics"—the examination of Earth from an imagined extraterrestrial viewpoint—is an important counterpart to the search for life "out there." It serves as a reminder of the obvious but profound premise that Earth is part of the cosmos. At a popular level we often continue to speak of "outer space" as if the old "two-storey" picture of the universe still had some residual legitimacy. However, if Galileo, Wilkins, and other devotees of the New Astronomy were right about Earth's being a full participant in "the dance of the stars," then "outer" is a merely relative and parochial term, not a scientific or qualitative one. And it is no trivial claim to assert that the search for intelligent life in the universe has already identified its first specimens.

  14. REFLEXIVITY AND RIGIDITY FOR COMPLEXES, II: SCHEMES ...

    E-print Network

    2011-09-11

    Feb 1, 2010 ... all noetherian schemes and their separated maps essentially of finite type. We work ... Quasi-Gorenstein maps are defined by the condition that f! .... The results above can be applied to complete some work started in [6]. ...... into a sheaf of commutative rings on X, whose stalk at any point x ? X is OY,f(x).

  15. Avoidance and management of trigeminocardiac reflex complicating awake-craniotomy.

    PubMed

    Prabhu, Vikram C; Bamber, Norman I; Shea, John F; Jellish, W Scott

    2008-12-01

    The trigeminocardiac reflex occurs from manipulation or stimulation of peripheral branches or the central component of the trigeminal nerve and consists of bradycardia, hypotension, apnea, and increased gastric motility. The efferent limb of the response is mediated by the vagus nerve. This 65-year-old Caucasian male suffered an episode of bradycardia progressing to transient asystole during the course of an awake-craniotomy procedure for tumor resection. The cardiac rhythm changes resolved with administration of intravenous atropine, removal of the precipitating stimulus, and application of topical anesthetic on the dura of the middle cranial fossa. The trigeminocardiac response may complicate the course of a craniotomy and may place an awake, unintubated patient at increased risk for morbidity. The reflex may be prevented by anesthetizing the dura innervated by the trigeminal nerve via injection or topical application of local anesthetic. If encountered, removal of the stimulus, airway protection, and administration of vagolytic medications are measures that need to be considered. PMID:18845385

  16. [A case of trigeminocardiac reflex in the pterional approach].

    PubMed

    Kitabayashi, Mayumi; Nakamura, Kazuhito; Murata, Takaho

    2012-10-01

    Trigeminocardiac reflex (TCR) is a type of vasovagal reflex which happens in stimulation of the trigeminal nerve. We present a case of TCR in the pterional approach for clipping of an unruptured anterior communicating artery (Acom) aneurysm. A 69-year-old female was evaluated because of syncope. MRI showed incidentally Acom aneurysm. During the operation for clipping this aneurysm, only when we manipulated the dura attached to the sphenoid ridge, a total of three times, asystole appeared temporarily. In this case, a branch of the trigeminal nerve accompanying the middle meningeal artery was stimulated, then TCR may have been induced, leading to asystole. Furthermore, it seems that remifentanil used for anesthesia is related to TCR. PMID:23045405

  17. Trigeminocardiac reflex: the current clinical and physiological knowledge.

    PubMed

    Chowdhury, Tumul; Mendelowith, David; Golanov, Eugene; Spiriev, Toma; Arasho, Belachew; Sandu, Nora; Sadr-Eshkevari, Pooyan; Meuwly, Cyrill; Schaller, Bernhard

    2015-04-01

    The trigeminocardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. Clinically, the TCR has been reported in all the surgical procedures in which a structure innervated by the trigeminal nerve is involved. Although, there is an abundant literature with reports of incidences and risk factors of the TCR; the physiological significance and function of this brainstem reflex has not yet been fully elucidated. In addition, there are complexities within the TCR that requires examination and clarification. There is also a growing need to discuss its cellular mechanism and functional consequences. Therefore, the current review provides an updated examination of the TCR with a particular focus on the mechanisms and diverse nature of the TCR. PMID:25602626

  18. Eye movements and vestibulo-ocular reflex in the blind

    E-print Network

    D. Kiimpf I; H. -f. Piper

    1987-01-01

    Summary. To assess the effect of chronic deprivation of visual feedback, 21 blind patients underwent clinical and electronystagmographical examination. Patients with congenital blindness were characterized by spontaneous eye movements, inability to consciously move the eyes and absence of the vestibulo-ocular reflex (VOR), whereas eye movement abnormalities were practically absent in those with blindness acquired late in life. Active visual experience, at least in early life, seems to be crucial for the development of eye movements and VOR adjustment. Key words: Development of eye movements- Blindness-Vestibulo-ocular reflex It is now well established that active visual experience is necessary for normal development of the mammalian visual system [20]. It is thus surprising that there have been few

  19. Lack of trigemino-cervical reflexes in progressive supranuclear palsy.

    PubMed

    Bartolo, Michelangelo; Serrao, Mariano; Perrotta, Armando; Tassorelli, Cristina; Sandrini, Giorgio; Pierelli, Francesco

    2008-07-30

    Trigemino-cervical reflexes (TCRs) are multisynaptic neck muscle withdrawal responses that are clearly identifiable in humans. Mediated by neural circuits at brainstem level, these reflex responses have been found to be significantly impaired in patients with Parkinson's disease (PD), and it has been hypothesized that a degeneration of brainstem neural structures could play a role in these abnormalities. Because extensive neuronal degeneration at brainstem level has been demonstrated in progressive supranuclear palsy (PSP), in this pilot study we evaluated the TCR responses in 12 subjects with PSP, and in 16 healthy controls. The TCRs were absent in 11 out of the 12 PSP patients while clear responses were evoked in all the healthy subjects. These findings indicate that PSP patients are unable to react to the painful stimuli to the face, suggesting a generalized impairment of the brainstem circuits mediating TCRs. PMID:18561341

  20. Frequency tuning of the contralateral medial olivocochlear reflex in humans

    PubMed Central

    Dhar, Sumitrajit

    2012-01-01

    Activation of the medial olivocochlear (MOC) efferents attenuates cochlear gain and reduces the amplitudes of mechanical, electrical, and neural cochlear outputs. The functional roles of the MOC efferents are not fully understood, especially in humans, despite postulations that they are involved in protection against acoustic trauma, facilitation of transient-sound perception, etc. Delineating the frequency tuning properties of the MOC efferents would provide critical evidence to support or refute these postulated functional roles. By utilizing spontaneous otoacoustic emissions (SOAEs), a cochlear measure sensitive to MOC modulation, we systematically demonstrate in humans that the contralateral MOC reflex is tuned to a fixed frequency band between 500 and 1,000 Hz independent of SOAE frequency. Our results question the role of the MOC reflex in protection against acoustic trauma or facilitation of transient-sound perception. PMID:22457463

  1. Interactions With Compliant Loads Alter Stretch Reflex Gains But Not Intermuscular Coordination

    PubMed Central

    Perreault, Eric J.; Chen, Kuifu; Trumbower, Randy D.; Lewis, Gwyn

    2009-01-01

    The human motor system regulates arm mechanics to produce stable postures during interactions with different physical environments. This occurs partly via involuntary mechanisms, including stretch reflexes. Previous single-joint studies demonstrated enhanced reflex sensitivity during interactions with compliant environments, suggesting reflex gain increases to enhance limb stability when that stability is not provided by the environment. This study examined whether similar changes in reflex gain are present throughout the limb following perturbations that simultaneously influence multiple joints. Furthermore, we investigated whether any observed modulation was accompanied by task-specific changes in reflex coordination across muscles, a question that cannot be addressed using single-joint perturbations. Reflexes were elicited during the maintenance of posture by perturbing the arm with a three degrees of freedom robot, configured to have isotropic stiffness of either 10 N/m (compliant) or 10 kN/m (stiff). Perturbation characteristics were matched in both environments. Reflex magnitude was quantified by the average rectified electromyogram, recorded from eight muscles crossing the elbow and shoulder. Reflex coordination was assessed using independent components analysis to compare reflex activation patterns during interactions with stiff and compliant environments. Stretch reflex sensitivity increased significantly in all muscles during interactions with the compliant environment and these changes were not due to changes in background muscle activity. However, there was no significant difference in the reflex coordination patterns observed during interactions with the stiff and compliant environments. These results suggest that reflex modulation occurred through altered use of fixed muscle coordination patterns rather than through a change in reflex coordination. PMID:18287550

  2. Flexibly specialized agencies? Reflexivity, identity, and the advertising industry

    Microsoft Academic Search

    D Leslie

    1997-01-01

    In this paper I examine the process of restructuring in advertising, an image-oriented industry, in the context of debates over flexible specialization and reflexive modernization. There have been far-reaching changes in the US advertising industry in the 1980s and 1990s, including the recent expansion of small, flexible, and more creatively based agencies or 'boutiques'. The growth of creative agencies reveals

  3. Trigeminocardiac reflex: a MaxFax literature review.

    PubMed

    Bohluli, Behnam; Ashtiani, Abbas Kazemi; Khayampoor, Anahita; Sadr-Eshkevari, Pooyan

    2009-08-01

    Trigeminocardiac reflex (TCR) is a shocking event in the course of operation involving the maxillofacial area. The authors have tried to present an overview on the history, clinical implications, literature review, anatomic and biologic basis, predisposing and triggering factors, and management of the event. Being familiar with the presentations, preventive measures, and management procedures are seemingly the most important aspects of the TCR to oral and maxillofacial surgeons and anesthesiologists. PMID:19615657

  4. Computing vertex-surjective homomorphisms to partially reflexive trees

    E-print Network

    Paulusma, Daniel

    of G to adjacent vertices of H, i.e., f(u)f(v) EH whenever uv EG. The problem H-Coloring is to testComputing vertex-surjective homomorphisms to partially reflexive trees Petr A. Golovach1 , Dani¨el Laboratories, South Road, Durham DH1 3LE, UK. {petr.golovach,daniel.paulusma,jian.song}@durham.ac.uk Abstract

  5. Impulsive Consumption and Reflexive Thought: Nudging Ethical Consumer Behavior

    Microsoft Academic Search

    Leonhard K. Lades

    2012-01-01

    The paper deals with impulsive consumption and highlights the roles that cognitive and motivational aspects of reflexive thought (namely self-control and self-image motives, respectively) play in intertemporal decisions. While self-control inhibits individuals from consuming impulsively, self-image motives can induce impulsive consumption. Based on recent neuroscientific findings about 'wanting'–'liking' dissociations, the paper presents a potential motivational mechanism underlying such impulsive consumption

  6. The Mammalian Diving Response: An Enigmatic Reflex to Preserve Life?

    PubMed Central

    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

  7. The Cough Reflex in Animals: Relevance to Human Cough Research

    Microsoft Academic Search

    Brendan J. Canning

    2008-01-01

    All mammalian species studied cough or display some similar respiratory reflex upon aerosol challenge with tussigenic stimuli\\u000a such as citric acid or capsaicin. Animals cough to the same stimuli that evoke coughing in humans, and therapeutic agents\\u000a that display antitussive effects in human studies also prevent coughing in animals. The many invasive procedures and complementary\\u000a in vitro studies possible in

  8. Adaptation of reflexive feedback during arm posture to different environments

    Microsoft Academic Search

    Erwin De Vlugt; Alfred C. Schouten; Frans C. T. Van Der Helm

    2002-01-01

    .  ?In this study we have examined the ability of the central nervous system (CNS) to use spinal reflexes to minimize displacements\\u000a during postural control while continuous force perturbations were applied at the hand. The subjects were instructed to minimize\\u000a the displacements of the hand from a reference position that resulted from the force perturbations. The perturbations were\\u000a imposed in one

  9. Reflex sympathetic dystrophy: an underreported syndrome in children?

    Microsoft Academic Search

    R.-A. Lemahieu; C. Laere; L. A. Verbruggen

    1988-01-01

    Two cases of reflex sympathetic dystrophy are described in a 13-year-old and a 10-year-old girl. In the latter, symptoms occurred consecutively in the right leg, the left foot and the left hand. In contrast to the usual findings in adults, bone scintigraphy showed decreased radio-isotope uptake in the affected area during the early phase. An electromyography performed in the younger

  10. Acceptance of the different denominations for reflex sympathetic dystrophy

    Microsoft Academic Search

    B Alvarez-Lario; Í Aretxabala-Alcíbar; J Alegre-López; J L Alonso-Valdivielso

    2001-01-01

    OBJECTIVETo elucidate the real impact in the medical literature of the different denominations for reflex sympathetic dystrophy (RSD).METHODSA search was performed through the Medline database (WinSPIRS, SilverPlatter International, NS), from 1995 to 1999, including the following descriptors: RSD, complex regional pain syndrome (CRPS), CRPS type I, algodystrophy, Sudeck, shoulder-hand syndrome, transient osteoporosis, causalgia, and CRPS type II.RESULTSThe descriptor RSD was

  11. Sacral reflex latency correlated by age and sex.

    PubMed

    Pradal-Prat, D; Peray, P; Mares, P; Costa, P

    1998-09-01

    This prospective study was undertaken on 190 subjects who had no prior central or peripheral nerve supply pathology and where the value of the sacral reflex latency was compared by age and sex in order to determine precise norms. There were 90 men whose age averaged 56.9 +/- 13 years and 100 women with an average age of 54 +/- 13.1. The reflex was obtained by stimulating the dorsal nerve of the penis and the clitoris and taking a reading in the intermediate part of the external anal sphincter muscle. An averaging technique was used (over 30 stimulation occurrences). The average intensity of the stimulation was 15 mA. The value of the stimulus reaction latency taken at the positive peak was analyzed statistically. The average value was 37.6 +/- 5.36 ms in male subjects and 46.6 +/- 8.08 in female subjects. In men, values varied from 36.6 +/- 4.26 ms at under 35 years of age and reached 42 +/- 3.52 ms at over 75 years. In women, values varied from 37.33 +/- 7.69 ms at under 35 years to 55.6 +/- 4.39 ms at over 75 years of age. In a previous article we discussed ageing features in nerves and muscles. These features are largely responsible for the occurrence of static pelvic problems. The purpose of this study is to compare the sacral reflex latency by sex and age in normal subjects. PMID:9783123

  12. A Case of Trigeminocardiac Reflex During Infrastructure Maxillectomy.

    PubMed

    Mohan, Suresh; Flis, Daniel W; O'Leary, Miriam A

    2014-05-01

    IMPORTANCE The trigeminocardiac reflex refers to the sudden development of bradycardia or even asystole with arterial hypotension from manipulation of any sensory branches of the trigeminal nerve. Although it has only rarely been associated with morbidity and tends to be self-limited with removal of the stimulus, it is an important phenomenon for head and neck surgeons to recognize and respond to. OBSERVATIONS We present the case of a woman in her late 60s with maxillary alveolar ridge squamous cell carcinoma who developed episodes of asystole and bradycardia during posterior maxillary manipulation for an infrastructure maxillectomy at a tertiary academic medical center. Administration of atropine and removal of the inciting stimulus sufficed to extinguish the episodes and allow procedure completion. CONCLUSIONS AND RELEVANCE The trigeminocardiac reflex can be provoked by a number of head and neck and skull base procedures including parotidectomy and posterior maxillectomy. Surgeons and anesthesiologists should be wary of inciting the reflex during manipulation of trigeminal branches. Careful dissection for prevention and early intervention with stimulus removal and anticholinergic use as needed are paramount to ensure good outcomes. PMID:24788865

  13. Reciprocal inhibition versus unloading response during stretch reflex in humans.

    PubMed

    Manning, C D; McDonald, P L L; Murnaghan, C D; Bawa, P

    2013-04-01

    Rotation of an upper limb joint produces excitatory stretch reflex peaks M1 and M2 in the stretched muscles and simultaneous decrease in electromyographic (EMG) activity in the shortened muscles. The objective of this study was to examine whether the decreased activity in the antagonists (rINHIB) is purely from unloading of the spindles or receives active inhibition involving inhibitory interneurons. If rINHIB is due only to unloading, then the termination of rINHIB should vary with the duration of perturbation used to elicit stretch reflex, namely shorter stretches should result in shorter values of decreased periods of EMG. To examine this question, rectangular pulses, ranging in duration from 25 to 150 ms, were used to stretch wrist flexors or extensors with a torque motor. These rectangular pulses resulted in joint rotations which peaked at times (T(peak)) ranging from approximately 75-160 ms. As shown by previous authors, when the duration of rotation was shortened, the magnitude of M1 did not change, while the magnitude of M2 decreased. However, termination time of rINHIB in the shortened muscles did not change with change in T(peak), implying thereby that unloading of spindles of the antagonist muscles is not the only mechanism for the reduction in activity and that inhibitory reflex pathways most likely contribute. Possible sources of inhibition are discussed for the short- and long-latency inhibition. PMID:23354665

  14. Trait Dominance Promotes Reflexive Staring at Masked Angry Body Postures

    PubMed Central

    Hortensius, Ruud; van Honk, Jack; de Gelder, Beatrice; Terburg, David

    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 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. PMID:25549321

  15. The carotid sinus baroreceptor reflex in conscious rabbits.

    PubMed Central

    Faris, I B; Iannos, J; Jamieson, G G; Ludbrook, J

    1980-01-01

    1. A method is described for altering the pressure across the wall of the carotid sinus in conscious rabbits by enclosing the carotid bifurcation in a rigid, fluid-filled capsule. The extracapsular arterial baroreceptors were denervated. 2. The baroreceptor--heart rate reflex, elicited by injecting vasoactive drugs or inflating aortic and vena caval cuffs, was used to test the new method. The function of the carotid sinus was shown to be unaffected by enclosure in the capsule. Denervation of the extracapsular baroreceptors reduced the gain of the baroreceptor--heart rate reflex two- to threefold. 3. The characteristics of the carotid baroreceptor reflex were studied in sixteen animals by the capsule method. Median estimates of maximum gain, and the range over which blood pressure changed, were 1.1 mmHg/mmHg and 57 mmHg respectively. There was good agreement between duplicate estimates made 1--20 days apart. 4. There was only a weak association between the effects on blood pressure and heart rate of altering carotid sinus transmural pressure. Autonomic blockade of the heart, so that its rate was fixed, did not reduce the gain or range of blood pressure change. PMID:7359409

  16. Hypnotizability, Hypnosis and Prepulse Inhibition of the Startle Reflex in Healthy Women: An ERP Analysis

    PubMed Central

    De Pascalis, Vilfredo; Russo, Emanuela

    2013-01-01

    A working model of the neurophysiology of hypnosis suggests that highly hypnotizable individuals (HHs) have more effective frontal attentional systems implementing control, monitoring performance, and inhibiting unwanted stimuli from conscious awareness, than low hypnotizable individuals (LHs). Recent studies, using prepulse inhibition (PPI) of the auditory startle reflex (ASR), suggest that HHs, in the waking condition, may show reduced sensory gating although they may selectively attend and disattend different stimuli. Using a within subject design and a strict subject selection procedure, in waking and hypnosis conditions we tested whether HHs compared to LHs showed a significantly lower inhibition of the ASR and startle-related brain activity in both time and intracerebral source localization domains. HHs, as compared to LH participants, exhibited (a) longer latency of the eyeblink startle reflex, (b) reduced N100 responses to startle stimuli, and (c) higher PPI of eyeblink startle and of the P200 and P300 waves. Hypnosis yielded smaller N100 waves to startle stimuli and greater PPI of this component than in the waking condition. sLORETA analysis revealed that, for the N100 (107 msec) elicited during startle trials, HHs had a smaller activation in the left parietal lobe (BA2/40) than LHs. Auditory pulses of pulse-with prepulse trials in HHs yielded less activity of the P300 (280 msec) wave than LHs, in the cingulate and posterior cingulate gyrus (BA23/31). The present results, on the whole, are in the opposite direction to PPI findings on hypnotizability previously reported in the literature. These results provide support to the neuropsychophysiological model that HHs have more effective sensory integration and gating (or filtering) of irrelevant stimuli than LHs. PMID:24278150

  17. Central trigeminocardiac reflex in pediatric neurosurgery: a case report and review of the literature

    PubMed Central

    2012-01-01

    Introduction Trigeminocardiac reflex is a well-known phenomenon in neurosurgery, craniofacial surgery, ophthalmology and interventional neuroradiology. Even though the trigeminocardiac reflex has become an important factor in skull base surgery and neurosurgery, the central form of trigeminocardiac reflex has only been described in adult subpopulations until now. Case presentation We present a clear form of repetitive trigeminocardiac reflex expressed during revision surgery of a giant (110×61mm) right temporoparietal meningioma in an 18-month-old male Caucasian patient. After cessation of the surgical stimulus, his heart rate and mean arterial blood pressure returned to normal physiological levels. The further follow-up was uneventful. Conclusion Our case demonstrates that the central trigeminocardiac reflex also exists in pediatric patients, especially if manipulating trigeminal innervated structures or around the nerve itself. Whether the incidence and the behavior of the trigeminocardiac reflex is similar in pediatric neurosurgery compared with adult patients has to be shown in further studies. PMID:23110862

  18. Effect of intrathecal baclofen on the monosynaptic reflex in humans: evidence for a postsynaptic action.

    PubMed Central

    Azouvi, P; Roby-Brami, A; Biraben, A; Thiebaut, J B; Thurel, C; Bussel, B

    1993-01-01

    Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosynaptic H-reflex in spinal patients was investigated. It could inhibit rapidly and profoundly monosynaptic reflexes in lower limbs, but did not modify Ia vibratory inhibition of the soleus H-reflex. To assess more precisely its effect on Ia afferents, an experimental paradigm using Ia heteronymous facilitation of the soleus H-reflex was used. Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve. This demonstrates that the main part of the inhibitory effect of baclofen on the H-reflex in spinal patients is not due to a presynaptic effect, suggesting a postsynaptic site of action. PMID:8505644

  19. Modulation of intrinsic and reflexive contributions to low-back stabilization due to vision, task instruction, and perturbation bandwidth.

    PubMed

    van Drunen, P; Koumans, Y; van der Helm, F C T; van Dieën, J H; Happee, R

    2015-03-01

    The goal of this study is to assess how reflexes and intrinsic properties contribute to low-back stabilization and modulate with conditions. Upper body sway was evoked by anterior-posterior platform translations, while subjects were seated with a restrained pelvis and free upper body. Kinematic analysis of trunk translations and rotations illustrated that a fixed rotation point between the vertebrae L4 and L5 adequately captures lumbar bending up to 5 Hz. To investigate the motor control modulation, the conditions varied in vision (eyes open or closed), task instruction (Balance naturally or Resist perturbations by minimizing low-back motions), and perturbation bandwidth (from 0.2 up to 1, 3 or 10 Hz). Frequency response functions and physiological modeling parameters showed substantial modulation between all conditions. The eyes-open condition led to trunk-in-space behavior with additional long-latency visual feedback and decreased proprioceptive feedback. The task instruction to resist led to trunk-on-pelvis stabilization behavior, which was achieved by higher co-contraction levels and increased reflexive velocity feedback. Perturbations below the low-back natural frequency (~1 Hz) led to trunk-on-pelvis stabilization behavior, mainly attributed to increased intrinsic damping. This indicates that bandwidth effects should not be ignored and that experiments with high-bandwidth perturbations do not fully represent the intrinsic and reflexive behavior during most (low-bandwidth) daily life activities. The neck stabilized the head orientation effectively (head rotation amplitudes 2 % of trunk), but did not effectively stabilize the head in space (global head translations exceeded trunk translations by 20 %). This indicates that low-back motor control is involved in head-in-space stabilization and could explain the low-back motor control modulations due to vision. PMID:25567085

  20. Postnatal temporal, spatial and modality tuning of nociceptive cutaneous flexion reflexes in human infants.

    PubMed

    Cornelissen, Laura; Fabrizi, Lorenzo; Patten, Deborah; Worley, Alan; Meek, Judith; Boyd, Stewart; Slater, Rebeccah; Fitzgerald, Maria

    2013-01-01

    Cutaneous flexion reflexes are amongst the first behavioural responses to develop and are essential for the protection and survival of the newborn organism. Despite this, there has been no detailed, quantitative study of their maturation in human neonates. Here we use surface electromyographic (EMG) recording of biceps femoris activity in preterm (<37 weeks gestation, GA) and term (? 37 weeks GA) human infants, less than 14 days old, in response to tactile, punctate and clinically required skin-breaking lance stimulation of the heel. We show that all infants display a robust and long duration flexion reflex (>4 seconds) to a single noxious skin lance which decreases significantly with gestational age. This reflex is not restricted to the stimulated limb: heel lance evokes equal ipsilateral and contralateral reflexes in preterm and term infants. We further show that infant flexion withdrawal reflexes are not always nociceptive specific: in 29% of preterm infants, tactile stimulation evokes EMG activity that is indistinguishable from noxious stimulation. In 40% of term infants, tactile responses are also present but significantly smaller than nociceptive reflexes. Infant flexion reflexes are also evoked by application of calibrated punctate von Frey hairs (vFh), 0.8-17.2 g, to the heel. Von Frey hair thresholds increase significantly with gestational age and the magnitude of vFh evoked reflexes are significantly greater in preterm than term infants. Furthermore flexion reflexes in both groups are sensitized by repeated vFh stimulation. Thus human infant flexion reflexes differ in temporal, modality and spatial characteristics from those in adults. Reflex magnitude and tactile sensitivity decreases and nociceptive specificity and spatial organisation increases with gestational age. Strong, relatively non-specific, reflex sensitivity in early life may be important for driving postnatal activity dependent maturation of targeted spinal cord sensory circuits. PMID:24124564

  1. Postnatal Temporal, Spatial and Modality Tuning of Nociceptive Cutaneous Flexion Reflexes in Human Infants

    PubMed Central

    Cornelissen, Laura; Fabrizi, Lorenzo; Patten, Deborah; Worley, Alan; Meek, Judith; Boyd, Stewart; Slater, Rebeccah; Fitzgerald, Maria

    2013-01-01

    Cutaneous flexion reflexes are amongst the first behavioural responses to develop and are essential for the protection and survival of the newborn organism. Despite this, there has been no detailed, quantitative study of their maturation in human neonates. Here we use surface electromyographic (EMG) recording of biceps femoris activity in preterm (<37 weeks gestation, GA) and term (?37 weeks GA) human infants, less than 14 days old, in response to tactile, punctate and clinically required skin-breaking lance stimulation of the heel. We show that all infants display a robust and long duration flexion reflex (>4 seconds) to a single noxious skin lance which decreases significantly with gestational age. This reflex is not restricted to the stimulated limb: heel lance evokes equal ipsilateral and contralateral reflexes in preterm and term infants. We further show that infant flexion withdrawal reflexes are not always nociceptive specific: in 29% of preterm infants, tactile stimulation evokes EMG activity that is indistinguishable from noxious stimulation. In 40% of term infants, tactile responses are also present but significantly smaller than nociceptive reflexes. Infant flexion reflexes are also evoked by application of calibrated punctate von Frey hairs (vFh), 0.8–17.2 g, to the heel. Von Frey hair thresholds increase significantly with gestational age and the magnitude of vFh evoked reflexes are significantly greater in preterm than term infants. Furthermore flexion reflexes in both groups are sensitized by repeated vFh stimulation. Thus human infant flexion reflexes differ in temporal, modality and spatial characteristics from those in adults. Reflex magnitude and tactile sensitivity decreases and nociceptive specificity and spatial organisation increases with gestational age. Strong, relatively non-specific, reflex sensitivity in early life may be important for driving postnatal activity dependent maturation of targeted spinal cord sensory circuits. PMID:24124564

  2. The oculocardiac reflex in an adult with a non-displaced orbital floor fracture.

    PubMed

    Kasi, Sundeep K; Gorovoy, Ian R; Vagefi, M Reza; Kersten, Robert C

    2014-08-01

    The current dogma is that the oculocardiac reflex from orbital trapdoor fractures occurs only in children and young adults. We present the occurrence of the oculocardiac reflex in an adult with a non-displaced orbital floor fracture. CT demonstrated the adventitia surrounding the inferior rectus trapped in and below the orbital floor fracture. The patient's oculocardiac reflex resolved by early next morning, presumably from the tissue escaping from the orbital floor defect. PMID:24830832

  3. Suppression of soleus H-reflex amplitude is graded with frequency of rhythmic arm cycling

    Microsoft Academic Search

    Sandra R. Hundza; E. Paul Zehr

    2009-01-01

    In humans, rhythmic arm cycling has been shown to significantly suppress the soleus H-reflex amplitude in stationary legs.\\u000a The specific nature of the relationship between frequency of arm cycling and H-reflex modulation in the legs has not been\\u000a explored. We speculated that the effect of arm cycling on reflexes in leg muscles is related to the neural control of arm

  4. Reflex limb dilatation following norepinephrine and angiotensin II in conscious dogs

    NASA Technical Reports Server (NTRS)

    Vatner, S. F.; Mcritchie, R. J.

    1976-01-01

    The extent to which norepinephrine (NE) and angiotensin II (AN) constrict the mesenteric, renal, and iliac beds in conscious dogs is evaluated with a view to elicit opposing reflex actions tempering the vasoconstriction in the limb of the animals tested. The afferent and efferent mechanisms mediating this reflex are analyzed. It is shown that intravenous NE and AN cause striking reflex iliac dilatation in the limb of the conscious dog. The afferent arc of this reflex involves both arterial baroreceptor and vagal path-ways, whereas the efferent mechanism involves an interaction of alpha-adrenergic and histaminergic receptors.

  5. The Effects of Cervical Traction on the Soleus H Reflex in Stroke Patients

    PubMed Central

    1998-01-01

    The purpose of this study was to investigate the effects of cervical traction on the soleus H reflex amplitude in stroke patients. Cervical traction with intensity of 3 kgw was performed on six stroke patients. The soleus H reflex was evoked before, during, and after the cervical traction. All subjects showed smaller H reflex amplitudes in the second and third minutes after traction than before the traction. The results suggested that cervical traction with intensity of 3 kgw inhibited the soleus H reflex amplitude several minutes after traction in stroke patients.

  6. Reduction of the linear reflex gain explained from the M1-M2 refractory period.

    PubMed

    Klomp, Asbjorn; de Vlugt, Erwin; Meskers, Carel G M; de Groot, Jurriaan H; Arendzen, J Hans; van der Helm, Frans C T

    2013-06-01

    Linear system identification methods combined with neuromechanical modeling enable the quantification of reflex gains from recorded joint angular perturbation, torque, and/or electromyography (EMG). However, the stretch reflex response as recorded by EMG consists of multiple consecutive activation volleys (M1 and M2 responses) separated by a period of reduced activity and is nonlinearly related to joint perturbation. The goal of this study is to assess to what extent linear assumptions hold when quantifying these reflexive responses. Series of ramp-and-hold angular perturbations with fixed velocity but different ramp durations (and, therefore, different amplitudes) were applied to the wrist joint of seven healthy volunteers. Evoked EMG responses were compared to the reflex response estimated from a common linear reflex model relating EMG to perturbation velocity. Model fits described the measured EMG responses best when the perturbation and M1 response durations were equivalent. With increasing perturbation duration, i.e., amplitude, EMG response increased but reflex gain decreased due to the inert period after M1, which is believed to be related to alignment of the refractory period of the motoneurons. For angular joint perturbations exceeding the M1 duration (coinciding with 2 (°) of wrist joint rotation in this study), reflex gain variation may be largely explained from a shortcoming of the linear model in describing the nonlinear reflex response, and in particular the period of low reflexive activity after M1. PMID:23358942

  7. Interactions between stretch and startle reflexes produce task-appropriate rapid postural reactions

    PubMed Central

    Shemmell, Jonathan

    2015-01-01

    Neural pathways underpinning startle reflex and limb stretch reflexes evolved independently and have served vastly different purposes. In their most basic form, the pathways responsible for these reflex responses are relatively simple processing units that produce a motoric response that is proportional to the stimulus received. It is becoming clear however, that rapid responses to external stimuli produced by human and non-human primates are context-dependent in a manner similar to voluntary movements. This mini review discusses the nature of startle and stretch reflex interactions in human and non-human primates and the involvement of the primary motor cortex in their regulation. PMID:25674055

  8. Females Exhibit Shorter Paraspinal Reflex Latencies than Males in Response to Sudden Trunk Flexion Perturbations

    PubMed Central

    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

  9. Implementation of a smartphone as a wireless gyroscope application for the quantification of reflex response.

    PubMed

    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. PMID:25570783

  10. Identification of intrinsic and reflexive contributions to low-back stiffness: medium-term reliability and construct validity.

    PubMed

    Larivière, Christian; Ludvig, Daniel; Kearney, Robert; Mecheri, Hakim; Caron, Jean-Maxime; Preuss, Richard

    2015-01-21

    This study aimed at testing the reliability and construct validity of a trunk perturbation protocol (TPP) that estimates the intrinsic and reflexive contributions to low-back stiffness. The TPP consists of a series of pseudorandom position-controlled trunk perturbations in an apparatus measuring forces and displacements at the harness surrounding the thorax. Intrinsic and reflexive contributions to low-back stiffness were estimated using a system identification procedure, leading to 12 parameters. Study 1 methods (reliability): 30 subjects performed five 75-s trials, on each of two separate days (eight weeks apart). Reliability was assessed using the generalizability theory, which allowed computing indexes of dependability (?, analogous to intraclass correlation coefficient) and standard errors of measurement (SEM). Study 2 methods (validity): 20 healthy subjects performed three 75-s trials for each of five experimental conditions assumed to provide different lumbar stiffness; testing the construct validity of the TPP using four conditions with different lumbar belt designs and one control condition without. Study 1 results (reliability): Learning was seen between the first and following trials. Consequently, reliability analyses were performed without the first trial. Simulations showed that averaging the scores of three trials can lead to acceptable reliability results for some TPP parameters. Study 2 results (validity): All lumbar belt designs increased low-back intrinsic stiffness, while only some of them decreased reflex stiffness, which support the construct validity of the TPP. Overall, these findings support the use of the TPP to test the effect of rehabilitation or between-groups differences with regards to trunk stiffness. PMID:25529140

  11. Neural reflex of the canine pylorus to intraduodenal acid infusion.

    PubMed

    Allescher, H D; Daniel, E E; Dent, J; Fox, J E; Kostolanska, F

    1989-01-01

    In 29 chloralose-urethane anesthetized dogs, a manometric assembly was inserted through a gastrostomy to monitor pressure of the pyloric region with a sleeve sensor. Antral and duodenal contractions were monitored with both manometric sideholes and serosal strain gauges. An additional tube channel allowed intraduodenal infusions 1-2 cm aborad from the pylorus. Intraluminal infusion of hydrochloric acid (0.1 N, 0.92 ml/min, for 2 min) reproducibly caused activation of motor activity in the pyloric region and peristaltic duodenal activity. Proximal duodenal activity probably contributed to the total phasic response recorded in the pylorus region. Excitatory responses could also be elicited by infusion of phenyl-biguanide (stimulant of sensory nerve endings), but not by control infusions with diluent (Krebs' buffer or saline). The motor response of the pyloric region to intraduodenal acid was blocked by intraduodenal application of 2% xylocaine. Atropine (30 micrograms/kg i.v. and 100 micrograms i.a.) or hexamethonium (10 mg/kg and 1 mg i.a.) markedly reduced or blocked the acid-induced pyloric motor response of this region but propranolol (1.0 mg/kg i.v. and 100 micrograms i.a.), phentolamine (1.5 mg/kg i.v. and 100 micrograms i.a.), or naloxone (200 micrograms/kg and 20 micrograms i.a.) had no effect. We believe these observations show the existence of a reflex from the duodenum to the pylorus in response to intraluminal stimuli mediated by a chain of cholinergic nerves. In the dog, endogenous opioid peptides do not contribute to the excitatory reflex pathway activated by intraduodenal acid or phenyl-biguanide. As intraluminal acid in the duodenum activates this reflex, it may play a role in the physiologic and pathophysiologic role of gastric emptying in this species. PMID:2562833

  12. Increased dietary salt intake enhances the exercise pressor reflex

    PubMed Central

    Tsuchimochi, Hirotsugu; Stone, Audrey J.; Stocker, Sean D.; Kaufman, Marc P.

    2013-01-01

    Increased dietary salt in rats has been shown to sensitize central sympathetic circuits and enhance sympathetic responses to several stressors, including hyperinsulinemia, intracerebroventricular injection of angiotensin, and electrical stimulation of sciatic nerve afferents. These findings prompted us to test the hypothesis that increased dietary salt enhanced the exercise pressor reflex. Male Sprague-Dawley rats were fed 0.1% (low) or 4.0% (high) NaCl chow for 2 to 3 wk. On the day of the experiment, the rats were decerebrated, and the hind limb muscles were statically contracted for 30 s by electrically stimulating the cut peripheral ends of the L4 and L5 ventral roots. We found that contraction produced a significantly greater increase in mean arterial pressure of rats fed 4.0% (n = 26) vs. 0.1% (n = 22) NaCl (24 ± 2 vs. 15 ± 2 mmHg, respectively; P < 0.05). Baseline mean arterial pressure was not different between groups (0.1%, 77 ± 4 vs. 4.0% NaCl, 80 ± 3 mmHg). Likewise, the tension time indexes were not different between the two groups (P = 0.42). Section of the L4 and L5 dorsal roots greatly attenuated both the pressor and cardioaccelerator responses to contraction in both groups of rats, an effect showing that the responses were reflex in origin. Finally, electrical stimulation of the lumbar sympathetic chain produced similar increases in mean arterial pressure and decreases in femoral arterial blood flow and conductance between rats fed 0.1% vs. 4.0% NaCl diets. We conclude that increased dietary salt enhances the exercise pressor reflex. PMID:24271488

  13. Rapid motor learning in the translational vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Zhou, Wu; Weldon, Patrick; Tang, Bingfeng; King, W. M.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    Motor learning was induced in the translational vestibulo-ocular reflex (TVOR) when monkeys were repeatedly subjected to a brief (0.5 sec) head translation while they tried to maintain binocular fixation on a visual target for juice rewards. If the target was world-fixed, the initial eye speed of the TVOR gradually increased; if the target was head-fixed, the initial eye speed of the TVOR gradually decreased. The rate of learning acquisition was very rapid, with a time constant of approximately 100 trials, which was equivalent to <1 min of accumulated stimulation. These learned changes were consolidated over >or=1 d without any reinforcement, indicating induction of long-term synaptic plasticity. Although the learning generalized to targets with different viewing distances and to head translations with different accelerations, it was highly specific for the particular combination of head motion and evoked eye movement associated with the training. For example, it was specific to the modality of the stimulus (translation vs rotation) and the direction of the evoked eye movement in the training. Furthermore, when one eye was aligned with the heading direction so that it remained motionless during training, learning was not expressed in this eye, but only in the other nonaligned eye. These specificities show that the learning sites are neither in the sensory nor the motor limb of the reflex but in the sensory-motor transformation stage of the reflex. The dependence of the learning on both head motion and evoked eye movement suggests that Hebbian learning may be one of the underlying cellular mechanisms.

  14. The Central Nervous Connections Involved in the Vomiting Reflex

    NASA Technical Reports Server (NTRS)

    Brizzee, K. R.; Mehler, W. R.

    1986-01-01

    The vomiting reflex may be elicited by a number of different types or classes of stimuli involving many varieties of receptor structures and considerable diversity in afferent pathways and central connections. Central relay or mediating structures thus may vary widely according to the type of initial emetic stimulus. The emetic circuits which have been most completely delineated to date are probably those in which the Chemoreceptor Trigger Zone (CTZ) in the Area Postrema (AP) functions as a key mediating structure. Even in this system, however, there are large gaps in our knowledge of the nerve tracts and central nervous connections involved. Knowledge of most other emetic circuits subserving the emetic reflex resulting from many diverse types of stimuli such, for example, as emotional stress (e.g. psychogenic vomiting, Wruble et al. 1982), pain (e.g. testicular trauma), and chemical or mechanical irritation of the gastrointestinal tract or urinary tract is quite incomplete at this time, thus precluding any very adequate description of their central connections at present. One physiological system, however, which has received considerable attention recently in relation to the vomiting reflex elicited by motion stimuli is the vestibular system. Due to the paucity of data on central nervous connections of several or the non-vestibular types of emetic stimuli cited above, we will devote most of our attention in this brief review to the central connections of the vestibular system which seem likely to be involved in the vomiting response to motion stimuli. However, the latter part of the review will be concerned with the concept of the reticular vomiting centre in relation to the ParviCellular Reticular Formation (PCRF), and will thus probably pertain to all of the many classes of emetic stimuli since it will address the question of the final common emetic pathway.

  15. Modification of Otolith Reflex Asymmetries Following Space Flight

    NASA Technical Reports Server (NTRS)

    Clarke, Andrew H.; Schoenfeld, Uwe; Wood, Scott J.

    2011-01-01

    We hypothesize that changes in otolith-mediated reflexes adapted for microgravity contribute to perceptual, gaze and postural disturbances upon return to Earth s gravity. Our goal was to determine pre- versus post-fight differences in unilateral otolith reflexes that reflect these adaptive changes. This study represents the first comprehensive examination of unilateral otolith function following space flight. Ten astronauts participated in unilateral otolith function tests three times pre-flight and up to four times after Shuttle flights from landing day through the subsequent 10 days. During unilateral centrifugation (UC, +/- 3.5cm at 400deg/s), utricular function was examined by the perceptual changes reflected by the subjective visual vertical (SVV) and by video-oculographic measurement of the otolith-mediated ocular counter-roll (OOR). Unilateral saccular reflexes were recorded by measurement of collic Vestibular Evoked Myogenic Potential (cVEMP). Although data from a few subjects were not obtained early post-flight, a general increase in asymmetry of otolith responses was observed on landing day relative to pre-flight baseline, with a subsequent reversal in asymmetry within 2-3 days. Recovery to baseline levels was achieved within 10 days. This fluctuation in the asymmetry measures appeared strongest for SVV, in a consistent direction for OOR, and in an opposite direction for cVEMP. These results are consistent with our hypothesis that space flight results in adaptive changes in central nervous system processing of otolith input. Adaptation to microgravity may reveal asymmetries in otolith function upon to return to Earth that were not detected prior to the flight due to compensatory mechanisms.

  16. Study of multicomponent plasma parameters in the pulsed reflex discharge

    E-print Network

    Kovtun, Yu V; Skibenko, E I; Larin, Yu V; Shapoval, A N; Volkov, E D; Yuferov, V B

    2010-01-01

    Parameters of a dense 10^13-10^14cm^-3) multicomponent gas-metal plasma in the pulsed reflex discharge with a moderate power (W \\leq 10 MW) have been studied. The dynamics of the plasma density in time, the mass-element composition of the plasma generated, the radial distribution of the electron density in plasma, the rotation velocity and the rotation frequency of a plasma layer with n_p \\geq n_crit, the radial electric field strength, and the recombination factor at the stage of plasma density decay in the discharge have been determined. The plasma particle separation factor has been evaluated.

  17. Abnormal Control of Orbicularis Oculi Reflex Excitability in Multiple Sclerosis

    PubMed Central

    Cabib, Christopher; Llufriu, Sara; Martinez-Heras, Eloy; Saiz, Albert; Valls-Solé, Josep

    2014-01-01

    Brain lesions in patients with multiple sclerosis may lead to abnormal excitability of brainstem reflex circuits because of impairment of descending control pathways. We hypothesized that such abnormality should show in the analysis of blink reflex responses in the form of asymmetries in response size. The study was done in 20 patients with relapsing-remitting multiple sclerosis and 12 matched healthy subjects. We identified first patients with latency abnormalities (AbLat). Then, we analyzed response size by calculating the R2c/R2 ratio to stimulation of either side and the mean area of the R2 responses obtained in the same side. Patients with significantly larger response size with respect to healthy subjects in at least one side were considered to have abnormal response excitability (AbEx). We also examined the blink reflex excitability recovery (BRER) and prepulse inhibition (BRIP) of either side in search for additional indices of asymmetry in response excitability. Neurophysiological data were correlated with MRI-determined brain lesion-load and volume. Eight patients were identified as AbLat (median Expanded Disability Status Scale–EDSS?=?2.75) and 7 of them had ponto-medullary lesions. Nine patients were identified as AbEx (EDSS?=?1.5) and only 2 of them, who also were AbLat, had ponto-medullary lesions. In AbEx patients, the abnormalities in response size were confined to one side, with a similar tendency in most variables (significantly asymmetric R1 amplitude, BRER index and BRIP percentage). AbEx patients had asymmetric distribution of hemispheral lesions, in contrast with the symmetric pattern observed in AbLat. The brainstem lesion load was significantly lower in AbEx than in AbLat patients (p?=?0.04). Asymmetric abnormalities in blink reflex response excitability in patients with multiple sclerosis are associated with lesser disability and lower tissue loss than abnormalities in response latency. Testing response excitability could provide a reliable neurophysiological index of dysfunction in early stages of multiple sclerosis. PMID:25083902

  18. Bone scintigraphy in the reflex sympathetic dystrophy syndrome

    SciTech Connect

    Kozin, F.; Soin, J.S.; Ryan, L.M.; Carrera, G.F.; Wortmann, R.L.

    1981-02-01

    Sixty-four consecutive patients were studied for possible reflex sympathetic dystrophy syndrome (RSDS). They were divided into five groups, based upon specific clinical criteria, and the radiographic and scintigraphic findings in each group were examined. Osteoporosis was the most common radiographic abnormality. Scintigraphic abnormalities were noted in 60% of RSDS patients but in only 7% of the others. These findings included increased blood flow and enhanced periarticular radionuclide activity in the affected extremity. The scan may reflect an active, potentially reversible disorder of local blood flow in RSDS. Furthermore, the scintigraphic patterns may be useful in the diagnosis and in predicting which patients are likely to respond to systemic steroid therapy.

  19. The reflex-diode HPM source on Aurora

    SciTech Connect

    Huttlin, G.A.; Bushell, M.S.; Conrad, D.B.; Davis, D.P.; Litz, M.S.; Ruth, B.G.; Agee, F.J. (Harry Diamond Labs., Adelphi, MD (USA)); Ebersole, K.L.; Judy, D.C.; Lezcano, P.A.; Pereira, N.R.; Weidenheimer, D.M. (Berkeley Research Associates, Springfield, VA (USA))

    1990-06-01

    This paper describes the most recent in a series of experiments to develop the reflex diode as a source of microwaves on the Aurora relativistic electron-beam pulser. The authors have achieved an overall output for radial extraction of {approximately} 400 J in microwave bursts from {approximately} 100 to 150 ns at frequencies below 1 GHz. The diagnostics for radial extraction have included directional couplers, card calorimeters, and free-field sensors. The authors have varied the anode/cathode spacing, downstream microwave reflector, and a second anode foil, but, within the range of variations, no strong trends have been noted.

  20. Calibration of ipsilateral stimulus transducer for acoustic reflex measurements.

    PubMed

    Olsen, S; Osterhammel, P A; Rasmussen, A N; Nielsen, L H

    1995-01-01

    Pure-tone Reference Equivalent Threshold Sound Pressure Level (RETSPL) of the ipsilateral stimulus receiver for acoustic reflex measurements on Madsen Electronics type Zodiac 901 impedance audiometer is provided. The results, obtained from 20 normal-hearing subjects, are achieved by comparing hearing threshold levels measured using a TDH 39 telephone (calibrated to ISO 389) with thresholds recorded using the ipsilateral stimulus insert phone. The calibration is referenced to an IEC-711 ear simulator and comprises the following frequencies: 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, 8000 Hz. PMID:8552975

  1. J Neurol Neurosurg Psychiatry . Author manuscript Multimodal imaging reveals the role of activity in eating-reflex seizures

    E-print Network

    Paris-Sud XI, Université de

    electroencephalography combined with functional magnetic resonance imaging, the overlap of the gustatory cortex ; physiopathology ; surgery ; Dominance, Cerebral ; physiology ; Electroencephalography ; Epilepsy, Reflex oscillations ; Gustatory Cortex ; Insula ; Reflex Epilepsy ; Stereo-Electroencephalography INTRODUCTION Fast

  2. Reflex apnea induced by high-frequency oscillatory ventilation in rabbits.

    PubMed

    Kohl, J; Freund, U; Koller, E A

    1991-05-01

    In rabbits with intact vagus nerves, HFOV applied for 10-20 s caused apnea (i.e., respiratory arrest for as long as HFOV lasted) accompanied by tonic discharges of the diaphragm. To identify the vagal mechanisms involved in this type of apnea, the vagus nerves of anaesthetized rabbits were gradually cooled from 37 degrees C to 0 degree C, i.e., the vagal fibres were, corresponding to their diameter, successively blocked. At each temperature, the effects of HFOV on spontaneous breathing were compared with those of static lung inflation and deflation: Between 20 degrees C and 14 degrees C, the lung inflation reflex (mediated by pulmonary slowly adapting stretch receptors = PSR) was weakened or abolished, whereas the lung deflation reflex (mediated by rapidly adapting stretch receptors = RAR) was reinforced; the HFOV-induced apnea occurred less frequently, however, the accompanying diaphragmatic activity was enhanced. Between 14 degrees C and 5 degrees C, both HFOV and large static inflation caused a slight increase of breathing frequency in the majority of animals. Some animals, however, responded even below 14 degrees C by apnea to both HFOV and inflation, and, under these conditions, both HFOV- and inflation-induced apnea were accompanied by a pronounced tonic diaphragmatic activity. At 5 degrees C, the effects of HFOV as well as of inflation (except in two animals) and deflation were abolished. From the results we conclude that in rabbits the apnea during HFOV is mainly mediated by stimulation of PSR, and the concomitant tonic activity of the diaphragm is mainly due to stimulation of RAR, as it is reinforced with gradual blockade of PSR fibres and abolished when only non-myelinated fibres are intact. PMID:1876760

  3. Theophylline inhibits the cough reflex through a novel mechanism of action?

    PubMed Central

    Dubuis, Eric; Wortley, Michael A.; Grace, Megan S.; Maher, Sarah A.; Adcock, John J.; Birrell, Mark A.; Belvisi, Maria G.

    2014-01-01

    Background Theophylline has been used in the treatment of asthma and chronic obstructive pulmonary disease for more than 80 years. In addition to bronchodilator and anti-inflammatory activity, clinical studies have suggested that theophylline acts as an antitussive agent. Cough is the most frequent reason for consultation with a family doctor, and treatment options are limited. Determining how theophylline inhibits cough might lead to the development of optimized compounds. Objective We sought to investigate the inhibitory activity of theophylline on vagal sensory nerve activity and the cough reflex. Methods Using a range of techniques, we investigated the effect of theophylline on human and guinea pig vagal sensory nerve activity in vitro and on the cough reflex in guinea pig challenge models. Results Theophylline was antitussive in a guinea pig model, inhibited activation of single C-fiber afferents in vivo and depolarization of human and guinea pig vagus in vitro, and inhibited calcium influx in airway-specific neurons in vitro. A sequence of pharmacological studies on the isolated vagus and patch clamp and single-channel inside-out experiments showed that the effect of theophylline was due to an increase in the open probability of calcium-activated potassium channels. Finally, we demonstrated the antitussive activity of theophylline in a cigarette smoke exposure model that exhibited enhanced tussive responses to capsaicin. Conclusion Theophylline inhibits capsaicin-induced cough under both normal and “disease” conditions by decreasing the excitability of sensory nerves through activation of small- and intermediate-conductance calcium-activated potassium channels. These findings could lead to the development of optimized antitussive compounds with a reduced side effect potential. PMID:24406072

  4. Controlling Dynamic Motions of Biped Robots with Reflexes and Motor Patterns

    E-print Network

    Berns, Karsten

    local reflexes and by exploiting the passive dynamics of the mechanical system. In [8Controlling Dynamic Motions of Biped Robots with Reflexes and Motor Patterns Tobias Luksch, Karsten of biped walking is still unequaled. Both the mechanical side and neural control surpass what robotics

  5. Changes in Soleus H-Reflex Modulation after Treadmill Training in Children with Cerebral Palsy

    ERIC Educational Resources Information Center

    Hodapp, Maike; Vry, Julia; Mall, Volker; Faist, Michael

    2009-01-01

    In healthy children, short latency leg muscle reflexes are profoundly modulated throughout the step cycle in a functionally meaningful way and contribute to the electromyographic (EMG) pattern observed during gait. With maturation of the corticospinal tract, the reflex amplitudes are depressed via supraspinal inhibitory mechanisms. In the soleus…

  6. Surface EMG Recording of the Perioral Reflexes: Preliminary Observations on Stutterers and Nonstutterers.

    ERIC Educational Resources Information Center

    McClean, Michael D.

    1987-01-01

    Surface electrodes were used to describe the perioral reflexes in seven stutterers and five nonstutterers and electromyographic (EMG) recordings were obtained at electrode sites associated with the orbicularis oris inferior muscle and the depressor labia inferior muscle. A difference was noted in the pattern of reflex response between the two…

  7. Encouraging Reflexivity in Urban Geography Fieldwork: Study Abroad Experiences in Singapore and Malaysia

    ERIC Educational Resources Information Center

    Glass, Michael R.

    2014-01-01

    Fieldwork in urban geography courses can encourage reflexivity among students regarding the cities they encounter. This article outlines how student reflexivity was encouraged within a new international field research course in Singapore and Malaysia. Drawing on examples from students' field exercises written during an intensive and…

  8. Windup of Flexion Reflexes in Chronic Human Spinal Cord Injury: A Marker for Neuronal Plateau Potentials?

    E-print Network

    Windup of Flexion Reflexes in Chronic Human Spinal Cord Injury: A Marker for Neuronal Plateau., W. Z. Rymer, E. N. Benz, and B. D. Schmit. Windup of flexion reflexes in chronic human spinal cord.2001. The physiological basis of flexion spasms in individuals after spinal cord injury (SCI) may involve alterations

  9. Nitric oxide modulates local reflexes of the tailfan of the crayfish

    Microsoft Academic Search

    Makoto Araki; Sawako Fujimoto; Toshiki Nagayama; Philip L. Newland

    2004-01-01

    Electrical stimulation of sensory neu- rons that innervate receptors on the tailfan of crayfish evokes a reflex response of motor neurons that produce movements of the blades of the tailfan, the uropods. We analyzed the modulatory effects of nitric oxide (NO) on the spike frequency of the reflex response. Bath appli- cation of L-arginine and SNAP, which elevate endoge- nous

  10. Anesthetic management of the trigeminocardiac reflex during mesiodens removal-a case report.

    PubMed

    Webb, Michael D; Unkel, John H

    2007-01-01

    We describe a case in which reflection of a palatal flap for removal of a mesiodens is presented as the triggering factor for bradycardia caused by stimulation of the trigeminocardiac reflex. The management of the case, as well as the reflex arc, is discussed. PMID:17352528

  11. Anesthetic Management of the Trigeminocardiac Reflex During Mesiodens Removal—A Case Report

    PubMed Central

    Webb, Michael D; Unkel, John H

    2007-01-01

    We describe a case in which reflection of a palatal flap for removal of a mesiodens is presented as the triggering factor for bradycardia caused by stimulation of the trigeminocardiac reflex. The management of the case, as well as the reflex arc, is discussed. PMID:17352528

  12. Trigeminocardiac Reflex in a Child During Pre-Onyx DMSO Injection for Juvenile Nasopharyngeal Angiofibroma Embolization

    PubMed Central

    Puri, A.S.; Thiex, R.; Zarzour, H.; Rahbar, R.; Orbach, D.B.

    2011-01-01

    Summary We describe the occurrence of the trigeminocardiac reflex (TCR) during DMSO pre-flushing of the microcatheter in preparation for Onyx embolization via the internal maxillary artery. TCR has not been previously associated with embolization of extradural entities. Familiarity with this clinical reflex and its proper management may help in planning neurointerventional procedures involving DMSO injection in the trigeminal territory. PMID:21561553

  13. Noradrenergic Modulation of Sensorimotor Processes in Intact Rats: The Masseteric Reflex as a Model System

    Microsoft Academic Search

    DAVID A. MORILAK; BARRY L. JACOBS

    The masseteric jaw closure reflex was utilized as a model system with which to gauge the functional activity of central noradrenergic neurons. This system was chosen because it is a simple monosynaptic reflex the neuronal substrate of which receives a dense noradrenergic input. The modulatory effects of norepinephrine (NE) on this response in the intact, chloral hydrate-anesthetized rat were studied

  14. A Comparison of Statistical Models for Calculating Reliability of the Hoffmann Reflex

    ERIC Educational Resources Information Center

    Christie, A.; Kamen, G.; Boucher, Jean P.; Inglis, J. Greig; Gabriel, David A.

    2010-01-01

    The Hoffmann reflex is obtained through surface electromyographic recordings, and it is one of the most common neurophysiological techniques in exercise science. Measurement and evaluation of the peak-to-peak amplitude of the Hoffmann reflex has been guided by the observation that it is a variable response that requires multiple trials to obtain a…

  15. Reflex control of the spine and posture: a review of the literature from a chiropractic perspective

    Microsoft Academic Search

    Mark W Morningstar; Burl R Pettibon; Heidi Schlappi; Mark Schlappi; Trevor V Ireland

    2005-01-01

    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

  16. The only honest thing: autoethnography, reflexivity and small crises in fieldwork

    Microsoft Academic Search

    Sara Delamont

    2009-01-01

    There has been a rising acceptance of autoethnography in the past 15 years. Instead of studying social phenomena, in an appropriately reflexive way, some scholars have taken to researching themselves. Drawing on concrete examples from an ongoing ethnographic project, the paper contrasts the beneficial, even essential, practices of autobiographical and reflexive thinking about fieldwork with the narcissistic substitution of autoethnography

  17. REFLEX MODULATION OF MOTONEURONE ACTIVITY IN THE CHELIPED OF THE CRAYFISH ASTACUS LEPTODACTYLUS

    Microsoft Academic Search

    J. P. VEDEL; D. ANGAUT-PETIT; F. CLARAC

    SUMMARY 1. The reflex activity elicited by movement of the mero-carpopodite (M-C) joint in the cheliped of the crayfish Astacus leptodactyhu is investi- gated and the role of the different proprioceptors (chordotonal and myo- chordotonal organs) separately studied. 2. The reflex discharge involves mainly the tonic motoneurones of the extensor (E), the flexor (F) and the accessory flexor (AF) muscles.

  18. Effect of stroke location on the laryngeal cough reflex and pneumonia risk

    Microsoft Academic Search

    W Robert Addington; Robert E Stephens; John G Widdicombe; Kamel Rekab

    2005-01-01

    BACKGROUND: The purpose of this study was to evaluate the risk of developing pneumonia in acute stroke patients comparing the early anatomical stroke location and laryngeal cough reflex (LCR) testing. METHODS: A prospective study of 818 consecutive acute stroke patients utilizing a reflex cough test (RCT), which assesses the neurological status of the LCR compared to magnetic resonance imaging or

  19. The teacher as reflexive professional: making visible the excluded discourse in teacher standards

    Microsoft Academic Search

    Mary Ryan; Terri Bourke

    2012-01-01

    In the current climate of accountability, political manoeuvring, changing curriculum, increasingly diverse student cohorts and community expectations, teachers, more than ever, need to develop the skills and abilities to be reflective and reflexive practitioners. This study examines national teacher professional standards from Australia and the UK to identify the extent to which reflexivity is embedded in key policy documents that

  20. A personal overview of causalgia and other reflex dystrophies.

    PubMed Central

    Shumacker, H B

    1985-01-01

    This is a personal assessment of true major causalgia and the other reflex dystrophies, related but distinctly separate entities. The clinical picture of causalgia differs only in minor respects from that described by Mitchell over 120 years ago. Its management has, however, been clarified, largely through the extensive experiences of World War II. It is readily recognized and can be treated effectively by sympathetic blocks or sympathectomy together with active exercise. The other reflex dystrophies are far less understood. They appear to have a similar pattern in their early phase and to respond well to a program of exercise and control of edema--a regimen which, because of pain and paresis, cannot be carried out without sympathetic blocks or occasionally sympathectomy. When not recognized early and treated properly, the sympatomatology usually changes dramatically and treatment differs. Often control of edema and active use of the affected part are all that is necessary. Sometimes, in addition to these measures, sympathetic blocks or sympathectomy is required. Guidelines found useful in management are outlined. Puzzling features are discussed. PMID:3977427

  1. Vestibulospinal control of reflex and voluntary head movement

    NASA Technical Reports Server (NTRS)

    Boyle, R.; Peterson, B. W. (Principal Investigator)

    2001-01-01

    Secondary canal-related vestibulospinal neurons respond to an externally applied movement of the head in the form of a firing rate modulation that encodes the angular velocity of the movement, and reflects in large part the input "head velocity in space" signal carried by the semicircular canal afferents. In addition to the head velocity signal, the vestibulospinal neurons can carry a more processed signal that includes eye position or eye velocity, or both (see Boyle on ref. list). To understand the control signals used by the central vestibular pathways in the generation of reflex head stabilization, such as the vestibulocollic reflex (VCR), and the maintenance of head posture, it is essential to record directly from identified vestibulospinal neurons projecting to the cervical spinal segments in the alert animal. The present report discusses two key features of the primate vestibulospinal system. First, the termination morphology of vestibulospinal axons in the cervical segments of the spinal cord is described to lay the structural basis of vestibulospinal control of head/neck posture and movement. And second, the head movement signal content carried by the same class of secondary vestibulospinal neurons during the actual execution of the VCR and during self-generated, or active, rapid head movements is presented.

  2. Coronary Spasm in Neurosurgical Patients and Role of Trigeminocardiac Reflex

    PubMed Central

    Sandu, Nora; Cappellani, Ronald B.

    2014-01-01

    Background. Coronary artery spasm (CAS) is a rarely reported complication in neurosurgical patients and its main causative mechanism was attributed to vagal mediated responses. However, these may be the unusual manifestations of trigeminal cardiac reflex (TCR) which is a well established brain stem reflex observed in various neurosurgical patients. Methods and Results. In this review, we have searched for the case reports/papers related to intraoperative coronary spasm in neurosurgical patients and described the role of TCR in this regard. TCR is a possible mechanism in producing CAS in most of the cases in which stimulation occurred at or near the vicinity of trigeminal nerve. It is likely that TCR mediated coronary spasm may be a physiological mechanism and not related to actual myocardial insult apparent by cardiac enzymes or echocardiography studies in most of the cases. Some common risk factors may also exist related to occurrence of CAS as well as TCR. Conclusions. In conclusion, neurosurgical procedures occurring at the vicinity of trigeminal nerve may produce CAS even in previously healthy patients and may produce catastrophic consequences. There is a need for future reports and experimental studies on the interaction of TCR and pathophysiological mechanisms related to CAS. PMID:24587903

  3. Coronary spasm in neurosurgical patients and role of trigeminocardiac reflex.

    PubMed

    Chowdhury, Tumul; Meuwly, Cyrill; Sandu, Nora; Cappellani, Ronald B; Schaller, Bernhard

    2014-01-01

    Background. Coronary artery spasm (CAS) is a rarely reported complication in neurosurgical patients and its main causative mechanism was attributed to vagal mediated responses. However, these may be the unusual manifestations of trigeminal cardiac reflex (TCR) which is a well established brain stem reflex observed in various neurosurgical patients. Methods and Results. In this review, we have searched for the case reports/papers related to intraoperative coronary spasm in neurosurgical patients and described the role of TCR in this regard. TCR is a possible mechanism in producing CAS in most of the cases in which stimulation occurred at or near the vicinity of trigeminal nerve. It is likely that TCR mediated coronary spasm may be a physiological mechanism and not related to actual myocardial insult apparent by cardiac enzymes or echocardiography studies in most of the cases. Some common risk factors may also exist related to occurrence of CAS as well as TCR. Conclusions. In conclusion, neurosurgical procedures occurring at the vicinity of trigeminal nerve may produce CAS even in previously healthy patients and may produce catastrophic consequences. There is a need for future reports and experimental studies on the interaction of TCR and pathophysiological mechanisms related to CAS. PMID:24587903

  4. Management of the trigeminocardiac reflex: facts and own experience.

    PubMed

    Arasho, Belachew; Sandu, Nora; Spiriev, Toma; Prabhakar, Hemanshu; Schaller, Bernhard

    2009-01-01

    The trigeminocardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hyper-motility during stimulation of any of the sensory branches of the trigeminal nerve. The proposed mechanism for the development of TCR is--the sensory nerve endings of the trigeminal nerve send neuronal signals via the Gasserian ganglion to the sensory nucleus of the trigeminal nerve, forming the afferent pathway of the reflex arc. It has been demonstrated that the TCR may occur with mechanical stimulation of all the branches of the trigeminal nerve anywhere along its course (central or peripheral). The reaction subsides with cessation of the stimulus. But, some patients may develop severe bradycardia, asystole, and arterial hypotension which require intervention. The risk factors already known to increase the incidence of TCR include: Hypercapnia; hypoxemia; light general anesthesia; age (more pronounced in children); the nature of the provoking stimulus (stimulus strength and duration); and drugs: Potent narcotic agents (sufentanil and alfentanil); beta-blockers; and calcium channel blockers. Because of the lack of full understanding of the TCR physiology, the current treatment options for patients with TCR include: (i) risk factor identification and modification; (ii) prophylactic measures; and (iii) administration of vagolytic agents or sympathomimetics. PMID:19770535

  5. Influence of gravity on cat vertical vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Tomko, D. L.; Wall, C., III; Robinson, F. R.; Staab, J. P.

    1988-01-01

    The vertical vestibulo-ocular reflex (VOR) was recorded in cats using electro-oculography during sinusoidal angular pitch. Peak stimulus velocity was 50 deg/s over a frequency range from 0.01 to 4.0 Hz. To test the effect of gravity on the vertical VOR, the animal was pitched while sitting upright or lying on its side. Upright pitch changed the cat's orientation relative to gravity, while on-side pitch did not. The cumulative slow component position of the eye during on-side pitch was less symmetric than during upright pitch. Over the mid-frequency range (0.1 to 1.0 Hz), the average gain of the vertical VOR was 14.5 percent higher during upright pitch than during on-side pitch. At low frequencies (less than 0.05 Hz) changing head position relative to gravity raised the vertical VOR gain and kept the reflex in phase with stimulus velocity. These results indicate that gravity-sensitive mechanisms make the vertical VOR more compensatory.

  6. Median sep and blink reflex in thyroid diseases.

    PubMed

    Oflazo?lu, B; Somay, G; Us, O; Surardamar, A; Tanrida?, T

    2006-11-01

    Pathological disturbances of thyroid hormones is associated with central and peripheral nervous system disturbances. The aim of this study is to evaluate median nerve stimulated somatosensory evoked potential (SEP) and blink reflex of thyroid patients (hypo and hyperthyroidism). Median SEP was performed in 40 patients (21 with hyperthyroidism and 19 with hypothyroidism). We evaluated the latencies of N9, N11, N13, P9, P11, P14, N20 and P25 waves and the N9-N20, N9-N13, N13-N20 and P14-N20 interpeak latencies. We compared the results of patients with the control group (26 persons). We found that the N20 latency was longer in patients with hyperthyroidism than in the control group and the difference was statistically significant. There was not any statistically significant difference regarding the N9, N11, N13, P9, P11, P14, N20 and P25 latencies and the N9-N20, N9-N13, N13-N20 and P14-N20 interpeak latencies between hypothyroid patients and controls. We performed the blink reflex study in 28 of 40 patients (14 patients with hyperthyroidism and 14 patients with hypothyroidism). Comparing the R1, R2, CR2 (contralateral R2) latencies and durations of the patients and controls, we found that R2 and CR2 duration was shorter in patients with hyperthyroidism. This difference was statistically significant. PMID:17147079

  7. Vestibulosympathetic reflex during orthostatic challenge in aging humans

    NASA Technical Reports Server (NTRS)

    Monahan, Kevin D.; Ray, Chester A.

    2002-01-01

    Aging attenuates the increase in muscle sympathetic nerve activity (MSNA) and elicits hypotension during otolith organ engagement in humans. The purpose of the present study was to determine the neural and cardiovascular responses to otolithic engagement during orthostatic stress in older adults. We hypothesized that age-related impairments in the vestibulosympathetic reflex would persist during orthostatic challenge in older subjects and might compromise arterial blood pressure regulation. MSNA, arterial blood pressure, and heart rate responses to head-down rotation (HDR) performed with and without lower body negative pressure (LBNP) in prone subjects were measured. Ten young (27 +/- 1 yr) and 11 older subjects (64 +/- 1 yr) were studied prospectively. HDR performed alone elicited an attenuated increase in MSNA in older subjects (Delta106 +/- 28 vs. Delta20 +/- 7% for young and older subjects). HDR performed during simultaneous orthostatic stress increased total MSNA further in young (Delta53 +/- 15%; P < 0.05) but not older subjects (Delta-5 +/- 4%). Older subjects demonstrated consistent significant hypotension during HDR performed both alone (Delta-6 +/- 2 mmHg) and during LBNP (Delta-7 +/- 2 mmHg). These data provide experimental support for the concept that age-related impairments in the vestibulosympathetic reflex persist during orthostatic challenge in older adults. Furthermore, these findings are consistent with the concept that age-related alterations in vestibular function might contribute to altered orthostatic blood pressure regulation with age in humans.

  8. Cerebral hemodynamic changes during the trigeminocardiac reflex: description of a new animal model protocol.

    PubMed

    Sandu, N; Cornelius, J; Filis, A; Nöthen, C; Rasper, J; Kulinsky, V I; Schaller, B J

    2010-01-01

    The trigeminocardiac reflex (TCR) is a well-known brainstem reflex, first described in skull base and neurosurgery by the senior author in 1999, leading to reflex apnea, bradycardia, and changes of mean arterial pressure. There seem to be differences between peripheral and central stimulation of the TCR, and there is a lack of clear data about the cerebral hemodynamic changes during the TCR. However, the research of this reflex principally focused on clinical cases for peripheral and central stimulation during the last years, and on rabbits for peripheral stimulation several decades ago, so there was a need for an animal model that allows us to use the current state-of-the-art imaging methods. The new animal model protocol as introduced by the authors gives, for the first time, deep insights into the cerebral hemodynamic changes during the TCR and gives substantial evidence whether the TCR represents an oxygen-conserving reflex or not. PMID:20661534

  9. Is initial preservation of deep tendon reflexes in West Nile Virus paralysis a good prognostic sign?

    PubMed Central

    Mojumder, Deb Kumar; Agosto, Melina; Wilms, Henrik; Kim, Jongyeol

    2014-01-01

    Typical West Nile virus paralysis is characterized by muscle weakness, decreased tone, and loss of deep tendon reflexes attributed to destruction of anterior horn cells. Two cases in which deep tendon reflexes were initially preserved in the presence of profound and persistent muscle weakness are presented here. In both cases, deep tendon reflexes were later severely attenuated or lost, while weakness of the involved muscles remained profound and unchanged. Both patients showed good motor recovery at 6 months. Initial preservation of deep tendon reflexes in the presence of persistent muscle weakness indicates that in the early stages of disease, the muscle weakness in these two cases was not caused by destruction of anterior horn cells. Pathology involving anterior horns preceding AHC destruction could potentially disrupt upper motor neuron pathways to anterior horn cells, causing weakness with initial preserved deep tendon reflexes. PMID:25400704

  10. Regulation of multijoint stretch reflexes during interactions with stiff and compliant environments.

    PubMed

    Perreault, Eric J; Chen, Kuifu; Lewis, Gwyn N

    2006-01-01

    The purpose of this study was to examine how multijoint stretch reflexes are modulated during interactions with stiff and compliant environments. Reflex responses were elicited using a 3D robotic manipulator to perturb arm posture in the three degrees of freedom relevant to functional behaviors. The robot applied controlled displacements and simulated environments with different stiffnesses. Stiff (10 kN/m) and compliant (10 N/m) environments were used. Perturbation characteristics were matched across environments. Reflex responses were monitored using surface electromyograms from 8 upper limb muscles. Data were collected from 9 subjects. Significant stretch reflex responses were observed in all muscles and these were significantly modulated by the environmental stiffness. This modulation was due to increased levels of background muscle activity in the compliant environment and to increased reflex sensitivity at matched levels of muscle activation. These results suggest that the neuromotor control system uses both feedforward and feedback mechanisms to compensate for changes in environmental compliance. PMID:17946812

  11. Review: Effect of drugs on human cough reflex sensitivity to inhaled capsaicin

    PubMed Central

    2012-01-01

    Capsaicin, the pungent extract of red peppers, has been used in clinical research for almost three decades. Capsaicin has gained favor as the provocative agent of choice to measure cough reflex sensitivity, as it induces cough in a safe, reproducible, and dose-dependent manner. One of the major uses of capsaicin cough challenge testing has been to evaluate the effect of a pharmacological intervention on the human cough reflex. The current review summarizes the published experience with capsaicin inhalation challenge in the evaluation of drug effects on cough reflex sensitivity. A notable contrast evident between studies demonstrating a drug effect (inhibition of cough reflex sensitivity) and those that do not, is the predominance of healthy volunteers as subjects in the latter. This observation suggests that subjects with pathological cough, rather than normal volunteers, comprise the optimal group in which to evaluate the effect of potential antitussive agents on human cough reflex sensitivity. PMID:23146824

  12. Neural mechanisms that contribute to cyclical modulation of the soleus H-reflex in walking in humans

    Microsoft Academic Search

    Jaynie F. Yang; Patrick J. Whelan

    1993-01-01

    The amplitude of the Hoffmann reflex (H-reflex) of the human soleus muscle is modulated in a cyclical way during walking. This paper addresses two questions associated with the neural mechanisms that might generate this modulation: (1) Does the amplitude of the H-reflex simply rise and fall as a function of the background excitability of the soleus motoneuron pool? (2) Is

  13. Association between melanopsin gene polymorphism (I394T) and pupillary light reflex is dependent on light wavelength

    PubMed Central

    2013-01-01

    Background Our aim was to determine the association between melanopsin gene polymorphism and pupillary light reflex under diverse photic conditions, including different intensities and wavelengths. Methods A total of 195 visually corrected subjects volunteered for investigation of the melanopsin gene of single nucleotide polymorphism (SNP) of rs1079610 (I394T). The genotype groups were TT (n = 126), TC (n = 55), and CC (n = 8), and 75 of the subjects, including subjects with TT (n = 34), TC (n = 33), and CC (n = 8) participated in our experiment. Three monochromatic lights with peak wavelengths of 465 nm (blue), 536 nm (green), and 632 nm (red) were prepared, and each light was projected to the subjects with five intensities, 12, 13, 14, 14.5 and 15 log photons/(cm2 s), for one minute. The pupil size of the left eye was measured under each light condition after a 1-minute adaptation. Results The pupils of the TC + CC genotypes (n = 38) were significantly smaller than those of the TT genotype (n = 31) under a blue (463 nm) light condition with 15 log photons/(cm2 s) (P < 0.05). In contrast, there were no significant differences under green (536 nm) and red (632 nm) light conditions. Conversely, relative pupil constrictions of the TC + CC genotypes were greater than those of the TT genotype under both blue and green conditions with high intensities (14.5 and 15 log photons/(cm2 s)). In contrast, there were no significant differences between genotype groups in pupil size and relative pupilloconstriction under the red light conditions. Conclusions Our findings suggest that the melanopsin gene polymorphism (I394T) functionally interacts with pupillary light reflex, depending on light intensity and, particularly, wavelength, and that under a light condition fulfilling both high intensity and short wavelength, the pupillary light response of subjects with the C allele (TC + CC) is more sensitive to light than that of subjects with the TT genotype. PMID:24119231

  14. Central Cannabinoid Receptors Modulate Acquisition of Eyeblink Conditioning

    ERIC Educational Resources Information Center

    Steinmetz, Adam B.; Freeman, John H.

    2010-01-01

    Delay eyeblink conditioning is established by paired presentations of a conditioned stimulus (CS) such as a tone or light, and an unconditioned stimulus (US) that elicits the blink reflex. Conditioned stimulus information is projected from the basilar pontine nuclei to the cerebellar interpositus nucleus and cortex. The cerebellar cortex,…

  15. Reflex control of the spine and posture: a review of the literature from a chiropractic perspective

    PubMed Central

    Morningstar, Mark W; Pettibon, Burl R; Schlappi, Heidi; Schlappi, Mark; Ireland, Trevor V

    2005-01-01

    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 during periods of microgravity or weightlessness. Background Historically, chiropractic has centered around the concept that the nervous system controls and regulates all other bodily systems; and that disruption to normal nervous system function can contribute to a wide variety of common ailments. Surprisingly, the chiropractic literature has paid relatively little attention to the importance of neurological regulation of static upright human posture. With so much information available on how posture may affect health and function, we felt it important to review the neuroanatomical structures and pathways responsible for maintaining the spine and posture. Maintenance of static upright posture is regulated by the nervous system through the various postural reflexes. Hence, from a chiropractic standpoint, it is clinically beneficial to understand how the individual postural reflexes work, as it may explain some of the clinical presentations seen in chiropractic practice. Method We performed a manual search for available relevant textbooks, and a computer search of the MEDLINE, MANTIS, and Index to Chiropractic Literature databases from 1970 to present, using the following key words and phrases: "posture," "ocular," "vestibular," "cervical facet joint," "afferent," "vestibulocollic," "cervicocollic," "postural reflexes," "spaceflight," "microgravity," "weightlessness," "gravity," "posture," and "postural." Studies were selected if they specifically tested any or all of the postural reflexes either in Earth's gravity or in microgravitational environments. Studies testing the function of each postural component, as well as those discussing postural reflex interactions, were also included in this review. Discussion It is quite apparent from the indexed literature we searched that posture is largely maintained by reflexive, involuntary control. While reflexive components for postural control are found in skin and joint receptors, somatic graviceptors, and baroreceptors throughout the body, much of the reflexive postural control mechanisms are housed, or occur, within the head and neck region primarily. We suggest that the postural reflexes may function in a hierarchical fashion. This hierarchy may well be based on the gravity-dependent or gravity-independent nature of each postural reflex. Some or all of these postural reflexes may contribute to the development of a postural body scheme, a conceptual internal representation of the external environment under normal gravity. This model may be the framework through which the postural reflexes anticipate and adapt to new gravitational environments. Conclusion Visual and vestibular input, as well as joint and soft tissue mechanoreceptors, are major players in the regulation of static upright posture. Each of these input sources detects and responds to specific types of postural stimulus and perturbations, and each region has specific pathways by which it communicates with other postural reflexes, as well as higher central nervous system structures. This review of the postural reflex structures and mechanisms adds to the growing body of posture rehabilitation literature relating specifically to chiropractic treatment. Chiropractic interest in these reflexes may enhance the ability of chiropractic physicians to treat and correct global spine and posture disorders. With the knowledge and understanding of these postural reflexes, chiropractors can evaluate spinal configurations not only from a segmental perspective, but can also determine how spinal dysfunction may be the ultimate consequence of maintaining an u

  16. Kinesio Taping in Young Healthy Subjects Does Not Affect Postural Reflex Reactions and Anticipatory Postural Adjustments of the Trunk: A Pilot Study

    PubMed Central

    Voglar, Matej; Sarabon, Nejc

    2014-01-01

    Therapeutic Kinesio Taping method is used for treatment of various musculo-skeletal conditions. Kinesio Taping might have some small clinically important beneficial effects on range of motion and strength but findings about the effects on proprioception and muscle activation are inconsistent. The aim of this study was to test if Kinesio Taping influences anticipatory postural adjustments and postural reflex reactions. To test the hypothesis twelve healthy young participants were recruited in randomized, participants blinded, placebo controlled cross-over study. In the experimental condition the tape was applied over the paravertebral muscles and in placebo condition sham application of the tape was done transversally over the lumbar region. Timing of anticipatory postural adjustments to fast voluntary arms movement and postural reflex reactions to sudden loading over the hands were measured by means of superficial electromyography before and one hour after each tape application. Results showed no significant differences between Kinesio Taping and placebo taping conditions for any of the analyzed muscles in anticipatory postural adaptations (F1,11 < 0.23, p > 0.64, ?2 < 0.04) or postural reflex reactions (F1,11 < 4.16, p > 0.07, ?2 < 0.49). Anticipatory postural adjustments of erector spinae and multifidus muscles were initiated significantly earlier after application of taping (regardless of technique) compared to pre-taping (F1,11 = 5.02, p = 0.046, ?2 = 0.31 and F1,11 = 6.18, p = 0.030, ?2 = 0.36 for erector spinae and multifidus, respectively). Taping application over lumbar region has potential beneficial effects on timing of anticipatory postural adjustments regardless of application technique but no effect on postural reflex reactions in young pain free participants. Further research in patients with low back pain would be encouraged. Key Points Application of Kinesio Taping does not affect postural reflex reactions in young healthy population. Earlier anticipatory postural adjustments were observed under both Kinesio Taping and placebo conditions. There were no significant differences between Kinesio Taping and placebo condition. PMID:25177198

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Effects of preceding movements and contractions on the tonic vibration reflex of human finger extensor muscles.

    PubMed

    Nordin, M; Hagbarth, K E

    1996-04-01

    The vibration sensitivity of feline muscle spindle endings is known to vary as a result of preceding muscle conditioning manoeuvres. If similar after-effects occur in man they should be expected to influence the strength of the tonic vibration reflex (TVR). To study this issue, vibration was applied over the finger extensor tendons of 11 volunteers who actively held their fingers in a semi-extended position. The TVR, measured as electromyographic responses and angular deflections at the metacarpophalangeal joints, was found to be stronger when the extensors prior to the test had been contracted in a shortened position than when they had been contracted in a stretched position. This difference was reduced when the vibration stimulus was preceded by a strong extensor contraction in the test position. The antigravity extensor EMG activity required to keep the fingers in the test position was weaker when the conditioning contraction was performed at a short muscle length than when it was performed at a long muscle length. The variations in magnitude of the TVR can be attributed to 'thixotropic' properties of intrafusal muscle fibres, resulting in a slack following conditioning at a long muscle length. The different EMG levels required for position holding can be explained by similar properties of extrafusal muscle fibres. In conclusion, the results demonstrate the importance of taking the 'history of movement' into account in the design of all TVR studies. PMID:8732248

  19. The effects of muscle history on short latency stretch reflex response of soleus muscle.

    PubMed

    Kallio, J; Linnamo, V; Komi, P V

    2004-06-01

    The purpose of the present study was to investigate the combined effects of muscle history, activation and stretching velocity on short latency stretch response (SLR). Stretches (70, 120 and 200 deg s-1) were elicited to both passive and active (10-25% MVC) triceps surae muscle with constant (ISO), lengthened (LEN) or shortened (SHO) muscle length. Under the passive SHO pre-condition both SLR amplitude and reflex torque (RT) decreased where as latency increased compared with the passive ISO pre-condition. Such observations were absent in active trials. Stretches applied to a lengthening passive muscle (LEN) resulted in smaller SLR amplitude and RT compared with passive ISO. In active muscle the stretch response increased with stretching velocity in ISO and SHO. However, in LEN there was large interindividual variability and no velocity dependent increase in SLR amplitude was observed. Smaller amplitude and longer latency of passive SLR in SHO could result from increased slack in the intrafusal fibres, which may be compensated by fusimotor activation during the active condition. The mechanism behind the smaller amplitude in passive LEN and the lack of velocity dependence in active LEN may be related to changes in motoneuron pool excitability or changes in the spindle sensitivity to stretch. PMID:15094154

  20. Gait acts as a gate for reflexes from the foot.

    PubMed

    Duysens, J; Bastiaanse, C M; Smits-Engelsman, B C M; Dietz, V

    2004-01-01

    During human gait, electrical stimulation of the foot elicits facilitatory P2 (medium latency) responses in TA (tibialis anterior) at the onset of the swing phase, while the same stimuli cause suppressive responses at the end of swing phase, along with facilitatory responses in antagonists. This phenomenon is called phase-dependent reflex reversal. The suppressive responses can be evoked from a variety of skin sites in the leg and from stimulation of some muscles such as rectus femoris (RF). This paper reviews the data on reflex reversal and adds new data on this topic, using a split-belt paradigm. So far, the reflex reversal in TA could only be studied for the onset and end phases of the step cycle, simply because suppression can only be demonstrated when there is background activity. Normally there are only 2 TA bursts in the step cycle, whereas TA is normally silent during most of the stance phase. To know what happens in the stance phase, one needs to have a means to evoke some background activity during the stance phase. For this purpose, new experiments were carried out in which subjects were asked to walk on a treadmill with a split-belt. When the subject was walking with unequal leg speeds, the walking pattern was adapted to a gait pattern resembling limping. The TA then remained active throughout most of the stance phase of the slow-moving leg, which was used as the primary support. This activity was a result of coactivation of agonistic and antagonistic leg muscles in the supporting leg, and represented one of the ways to stabilize the body. Electrical stimulation was given to a cutaneous nerve (sural) at the ankle at twice the perception threshold. Nine of the 12 subjects showed increased TA activity during stance phase while walking on split-belts, and 5 of them showed pronounced suppressions during the first part of stance when stimuli were given on the slow side. It was concluded that a TA suppressive pathway remains open throughout most of the stance phase in the majority of subjects. The suggestion was made that the TA suppression increases loading of the ankle plantar flexors during the loading phase of stance. PMID:15523528

  1. A new predisposing factor for trigemino-cardiac reflex during subdural empyema drainage: a case report

    PubMed Central

    2010-01-01

    Introduction The trigemino-cardiac reflex is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. Clinically, trigemino-cardiac reflex has been reported to occur during neurosurgical skull-base surgery. Apart from the few clinical reports, the physiological function of this brainstem reflex has not yet been fully explored. Little is known regarding any predisposing factors related to the intraoperative occurrence of this reflex. Case presentation We report the case of a 70-year-old Caucasian man who demonstrated a clearly expressed form of trigemino-cardiac reflex with severe bradycardia requiring intervention that was recorded during surgical removal of a large subdural empyema. Conclusion To the best of our knowledge, this is the first report of an intracranial infection leading to perioperative trigemino-cardiac reflex. We therefore add a new predisposing factor for trigemino-cardiac reflex to the existing literature. Possible mechanisms are discussed in the light of the relevant literature. PMID:21118536

  2. The Neuroanatomical Correlates of Training-Related Perceptuo-Reflex Uncoupling in Dancers

    PubMed Central

    Nigmatullina, Yuliya; Hellyer, Peter J.; Nachev, Parashkev; Sharp, David J.; Seemungal, Barry M.

    2015-01-01

    Sensory input evokes low-order reflexes and higher-order perceptual responses. Vestibular stimulation elicits vestibular-ocular reflex (VOR) and self-motion perception (e.g., vertigo) whose response durations are normally equal. Adaptation to repeated whole-body rotations, for example, ballet training, is known to reduce vestibular responses. We investigated the neuroanatomical correlates of vestibular perceptuo-reflex adaptation in ballet dancers and controls. Dancers' vestibular-reflex and perceptual responses to whole-body yaw-plane step rotations were: (1) Briefer and (2) uncorrelated (controls' reflex and perception were correlated). Voxel-based morphometry showed a selective gray matter (GM) reduction in dancers' vestibular cerebellum correlating with ballet experience. Dancers' vestibular cerebellar GM density reduction was related to shorter perceptual responses (i.e. positively correlated) but longer VOR duration (negatively correlated). Contrastingly, controls' vestibular cerebellar GM density negatively correlated with perception and VOR. Diffusion-tensor imaging showed that cerebral cortex white matter (WM) microstructure correlated with vestibular perception but only in controls. In summary, dancers display vestibular perceptuo-reflex dissociation with the neuronatomical correlate localized to the vestibular cerebellum. Controls' robust vestibular perception correlated with a cortical WM network conspicuously absent in dancers. Since primary vestibular afferents synapse in the vestibular cerebellum, we speculate that a cerebellar gating of perceptual signals to cortical regions mediates the training-related attenuation of vestibular perception and perceptuo-reflex uncoupling. PMID:24072889

  3. The neuroanatomical correlates of training-related perceptuo-reflex uncoupling in dancers.

    PubMed

    Nigmatullina, Yuliya; Hellyer, Peter J; Nachev, Parashkev; Sharp, David J; Seemungal, Barry M

    2015-02-01

    Sensory input evokes low-order reflexes and higher-order perceptual responses. Vestibular stimulation elicits vestibular-ocular reflex (VOR) and self-motion perception (e.g., vertigo) whose response durations are normally equal. Adaptation to repeated whole-body rotations, for example, ballet training, is known to reduce vestibular responses. We investigated the neuroanatomical correlates of vestibular perceptuo-reflex adaptation in ballet dancers and controls. Dancers' vestibular-reflex and perceptual responses to whole-body yaw-plane step rotations were: (1) Briefer and (2) uncorrelated (controls' reflex and perception were correlated). Voxel-based morphometry showed a selective gray matter (GM) reduction in dancers' vestibular cerebellum correlating with ballet experience. Dancers' vestibular cerebellar GM density reduction was related to shorter perceptual responses (i.e. positively correlated) but longer VOR duration (negatively correlated). Contrastingly, controls' vestibular cerebellar GM density negatively correlated with perception and VOR. Diffusion-tensor imaging showed that cerebral cortex white matter (WM) microstructure correlated with vestibular perception but only in controls. In summary, dancers display vestibular perceptuo-reflex dissociation with the neuronatomical correlate localized to the vestibular cerebellum. Controls' robust vestibular perception correlated with a cortical WM network conspicuously absent in dancers. Since primary vestibular afferents synapse in the vestibular cerebellum, we speculate that a cerebellar gating of perceptual signals to cortical regions mediates the training-related attenuation of vestibular perception and perceptuo-reflex uncoupling. PMID:24072889

  4. Plasticity of reflexes from the foot during locomotion after denervating ankle extensors in intact cats.

    PubMed

    Frigon, Alain; Rossignol, Serge

    2007-10-01

    Although sensory feedback is important in regulating the timing and magnitude of muscle activity during locomotion few studies have evaluated how it changes after peripheral nerve lesions. To assess this, reflexes evoked by stimulating a nerve before and after denervating other nerves can be quantified to determine changes. The aim of this study was to investigate consequences of denervating ankle extensor muscles, the lateral gastrocnemius, and soleus (LGS) on reflexes from the plantar foot surface evoked by stimulating the tibialis (Tib) nerve. Three cats (n = 3) were trained to walk on a treadmill and chronically implanted with electrodes in 14 hindlimb muscles bilaterally to record EMG activity. A stimulating cuff electrode was placed around the left Tib nerve (Tib) nerve at the ankle to evoke reflexes. Several control values of EMGs, limb kinematics, and Tib nerve reflexes were obtained during locomotion for at least 3 wk before the left LGS nerve was cut. We found that the locomotor EMG bursts of several muscles was altered, with a large increase in amplitude in the early days postneurectomy followed by a gradual decrease toward intact values later on. There were changes in the stimulated locomotor EMG bursts (Tib nerve reflexes) of ipsilateral flexors and extensors and of contralateral ankle extensors, which dissociated from changes in baseline locomotor EMG (e.g., nonstimulated bursts during reflex trials). The functional significance of these changes in muscle activity and reflex pathways on the recovery of locomotion after denervating ankle extensors is discussed. PMID:17652411

  5. [Axon-reflex based nerve fiber function assessment in the detection of autonomic neuropathy].

    PubMed

    Siepmann, T; Illigens, B M-W; Reichmann, H; Ziemssen, T

    2014-10-01

    Axon-reflex-based tests of peripheral small nerve fiber function including techniques to quantify vasomotor and sudomotor responses following acetylcholine iontophoresis are used in the assessment of autonomic neuropathy. However, the established axon-reflex-based techniques, laser Doppler flowmetry (LDF) to assess vasomotor function and quantitative sudomotor axon-reflex test (QSART) to measure sudomotor function, are limited by technically demanding settings as well as interindividual variability and are therefore restricted to specialized clinical centers. New axon-reflex tests are characterized by quantification of axon responses with both temporal and spatial resolution and include "laser Doppler imaging (LDI) axon-reflex flare area test" to assess vasomotor function, the quantitative direct and indirect test of sudomotor function (QDIRT) to quantify sudomotor function, as well as the quantitative pilomotor axon-reflex test (QPART), a technique to measure pilomotor nerve fiber function using adrenergic cutaneous stimulation through phenylephrine iontophoresis. The effectiveness of new axon-reflex tests in the assessment of neuropathy is currently being investigated in clinical studies. PMID:25047406

  6. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    SciTech Connect

    Toader, E.I.; Covlea, V.N. [Faculty of Physics, University of Bucharest, Box MG-11, 077125 Bucharest-Magurele (Romania)

    2005-03-01

    The effect of enhanced magnetic ionization on the external and internal parameters of a high-density, low pressure reflex plasma source operating in hydrogen is studied. The Langmuir probe method and Druyvesteyn procedure coupled with suitable software are used to measure the internal parameters. The bulk plasma region is free of an electric field and presents a high degree of uniformity. The electron energy distribution function is bi-Maxwellian with a dip/shoulder structure around 5.5 eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density n{sub e} is as high as 10{sup 18} m{sup -3}, and the electron temperature T{sub e} is as low as a few tens of an electron volt, for dissipated energy of tens of Watts. The bulk plasma density scales with the dissipated power.

  7. Who's arguing? A call for reflexivity in bioethics.

    PubMed

    Ives, Jonathan; Dunn, Michael

    2010-06-01

    In this paper we set forth what we believe to be a relatively controversial argument, claiming that 'bioethics' needs to undergo a fundamental change in the way it is practised. This change, we argue, requires philosophical bioethicists to adopt reflexive practices when applying their analyses in public forums, acknowledging openly that bioethics is an embedded socio-cultural practice, shaped by the ever-changing intuitions of individual philosophers, which cannot be viewed as a detached intellectual endeavour. This said, we argue that in order to manage the personal, social and cultural embeddedness of bioethics, philosophical bioethicists should openly acknowledge how their practices are constructed and should, in their writing, explicitly deal with issues of bias and conflict of interest, just as empirical scientists are required to do. PMID:20500762

  8. Towards an Autonomic Cluster Management System (ACMS) with Reflex Autonomicity

    NASA Technical Reports Server (NTRS)

    Truszkowski, Walt; Hinchey, Mike; Sterritt, Roy

    2005-01-01

    Cluster computing, whereby a large number of simple processors or nodes are combined together to apparently function as a single powerful computer, has emerged as a research area in its own right. The approach offers a relatively inexpensive means of providing a fault-tolerant environment and achieving significant computational capabilities for high-performance computing applications. However, the task of manually managing and configuring a cluster quickly becomes daunting as the cluster grows in size. Autonomic computing, with its vision to provide self-management, can potentially solve many of the problems inherent in cluster management. We describe the development of a prototype Autonomic Cluster Management System (ACMS) that exploits autonomic properties in automating cluster management and its evolution to include reflex reactions via pulse monitoring.

  9. Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Wood, Scott J.; Reschke, Millard F.

    1996-01-01

    It was hypothesized that the absence of the gravitational reference cues may be responsible for adaptive changes in the vestibulo-ocular reflex (VOR). These changes result in the alteration of the direction of the compensatory slow phase (SP) eye movements in microgravity. In order to test this hypothesis, the direction of the VOR SP relative to head motion was investigated in three astronauts during and after an eight-day orbital flight by passive sinusoidal pitch or yaw angular motion at two frequencies. The results of the inflight and postflight testing are considered. The observed deviation between VOR SP and head motion suggests that spatial transformation in the VOR occurred during adaptation to microgravity. It is considered that, although this spatial transformation might be due to a sensory bias, it may reflect central changes in the reference system used for spatial orientation in microgravity.

  10. Local reflexive mechanisms essential for snakes' scaffold-based locomotion.

    PubMed

    Kano, Takeshi; Sato, Takahide; Kobayashi, Ryo; Ishiguro, Akio

    2012-12-01

    Most robots are designed to work in predefined environments, and irregularities that exist in the environment interfere with their operation. For snakes, irregularities play the opposite role: snakes actively utilize terrain irregularities and move by effectively pushing their body against the scaffolds that they encounter. Autonomous decentralized control mechanisms could be the key to understanding this locomotion. We demonstrate through modelling and simulations that only two local reflexive mechanisms, which exploit sensory information about the stretching of muscles and the pressure on the body wall, are crucial for realizing locomotion. This finding will help develop robots that work in undefined environments and shed light on the understanding of the fundamental principles underlying adaptive locomotion in animals. PMID:22918023

  11. Modeling multistage decision processes with Reflexive Game Theory

    E-print Network

    Tarasenko, Sergey

    2012-01-01

    This paper introduces application of Reflexive Game Theory to the matter of multistage decision making processes. The idea behind is that each decision making session has certain parameters like "when the session is taking place", "who are the group members to make decision", "how group members influence on each other", etc. This study illustrates the consecutive or sequential decision making process, which consist of two stages. During the stage 1 decisions about the parameters of the ultimate decision making are made. Then stage 2 is implementation of Ultimate decision making itself. Since during stage 1 there can be multiple decision sessions. In such a case it takes more than two sessions to make ultimate (final) decision. Therefore the overall process of ultimate decision making becomes multistage decision making process consisting of consecutive decision making sessions.

  12. Developmental tuning of reflexive attentional effect to biological motion cues

    PubMed Central

    Zhao, Jing; Wang, Li; Wang, Ying; Weng, Xuchu; Li, Su; Jiang, Yi

    2014-01-01

    The human visual system is extremely sensitive to the direction information retrieved from biological motion. In the current study, we investigate the functional impact of this sensitivity on attentional orienting in young children. We found that children as early as 4 years old, like adults, showed a robust reflexive attentional orienting effect to the walking direction of an upright point-light walker, indicating that biological motion signals can automatically direct spatial attention at an early age. More importantly, the inversion effect associated with attentional orienting emerges by 4 years old and gradually develops into a similar pattern found in adults. These results provide strong evidence that biological motion cues can guide the distribution of spatial attention in young children, and highlight a critical development from a broadly- to finely-tuned process of utilizing biological motion cues in the human social brain. PMID:24990449

  13. A procedure concept for local reflex control of grasping

    NASA Technical Reports Server (NTRS)

    Fiorini, Paolo; Chang, Jeffrey

    1989-01-01

    An architecture is proposed for the control of robotic devices, and in particular of anthropomorphic hands, characterized by a hierarchical structure in which every level of the architecture contains data and control function with varying degree of abstraction. Bottom levels of the hierarchy interface directly with sensors and actuators, and process raw data and motor commands. Higher levels perform more symbolic types of tasks, such as application of boolean rules and general planning operations. Layers implementation has to be consistent with the type of operation and its requirements for real time control. It is proposed to implement the rule level with a Boolean Artificial Neural Network characterized by a response time sufficient for producing reflex corrective action at the actuator level.

  14. Electrophysiological study of the bulbocavernosus reflex: normative data.

    PubMed

    Granata, Giuseppe; Padua, Luca; Rossi, Fabiana; De Franco, Paola; Coraci, Daniele; Rossi, Vincenzo

    2013-01-01

    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 the greatest clinical utility. Previous normative data were obtained on small samples. The aim of this study was to determine normative values for the BCR in a large sample of men. We studied a large population (105 men; mean age 53 years, range 19-73 years) without central or peripheral neurological diseases. In each subject the sacral reflex was elicited by electrical stimulation of the base of the dorsum penis and recorded using a surface electrode from the BC muscle. We recorded the latency, calculated at onset, and the maximal amplitude of response, calculated peak to peak. We were able to detect the BCR in all the men. No correlation between BCR latency and age was found (r=0.136; p=0.160). The mean onset latency value was 33.0±4.85 ms (mean±2SD, range 26.8-39.4). The mean amplitude value was 16.53±12.21 ?V (mean±2SD, range 4.2-43.6). Our normative data on the BCR were similar to previously published data. PMID:24598398

  15. Electrophysiological study of the bulbocavernosus reflex: normative data.

    PubMed

    Granata, G; Padua, L; Rossi, F; De Franco, P; Coraci, D; Rossi, V

    2013-12-01

    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 the greatest clinical utility. Previous normative data were obtained on small samples. The aim of this study was to determine normative values for the BCR in a large sample of men. We studied a large population (105 men; mean age 53 years, range 19-73 years) without central or peripheral neurological diseases. In each subject the sacral reflex was elicited by electrical stimulation of the base of the dorsum penis and recorded using a surface electrode from the BC muscle. We recorded the latency, calculated at onset, and the maximal amplitude of response, calculated peak to peak. We were able to detect the BCR in all the men. No correlation between BCR latency and age was found (r=0.136; p=0.160). The mean onset latency value was 33.0±4.85 ms (mean±2SD, range 26.8-39.4). The mean amplitude value was 16.53±12.21 ?V (mean±2SD, range 4.2-43.6). Our normative data on the BCR were similar to previously published data. PMID:24300036

  16. Electrophysiological study of the bulbocavernosus reflex: normative data

    PubMed Central

    Granata, Giuseppe; Padua, Luca; Rossi, Fabiana; De Franco, Paola; Coraci, Daniele; Rossi, Vincenzo

    2013-01-01

    Summary 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 the greatest clinical utility. Previous normative data were obtained on small samples. The aim of this study was to determine normative values for the BCR in a large sample of men. We studied a large population (105 men; mean age 53 years, range 19–73 years) without central or peripheral neurological diseases. In each subject the sacral reflex was elicited by electrical stimulation of the base of the dorsum penis and recorded using a surface electrode from the BC muscle. We recorded the latency, calculated at onset, and the maximal amplitude of response, calculated peak to peak. We were able to detect the BCR in all the men. No correlation between BCR latency and age was found (r=0.136; p=0.160). The mean onset latency value was 33.0±4.85 ms (mean±2SD, range 26.8–39.4). The mean amplitude value was 16.53±12.21 ?V (mean±2SD, range 4.2–43.6). Our normative data on the BCR were similar to previously published data. PMID:24598398

  17. Cough reflex sensitivity in adolescents with diabetic autonomic neuropathy

    PubMed Central

    2009-01-01

    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 ?mol/l, IQR 68.4-625.0 ?mol/l vs. median 29.3 ?mol/l, IQR 9.8-156.3 ?mol/l, P < 0.001) and 5 coughs (median 2500.0 ?mol/l, IQR 1250.0-2500.0 ?mol/l vs. median 312.5 ?mol/l, IQR 117.2-625.0 ?mol/l, P < 0.001) compared with those without DAN. Moreover, a strong negative correlation between HRV and CRS was established. Conclusion Diabetes mellitus lowers the cough response. Cough reflex sensitivity appears to be another sensitive method for the evaluation of DAN in diabetes. PMID:20156724

  18. Trigeminocardiac reflex in neurosurgical practice: Report of two new cases

    PubMed Central

    Amirjamshidi, Abbas; Abbasioun, Kazem; Etezadi, Farhad; Ghasemi, Seyed Babak

    2013-01-01

    Background: Systemic hypotension, cardiac dysrhythmia especially bradycardia, apnea, and gastric hypermotility occurring presumably after stimulation of any of the sensory branches of trigeminal nerve are coined as trigeminocardiac reflex (TCR). Neither enough is known about the predisposing factors in relation with the intraoperative occurrence of this life threatening reflex, nor about the exact pathophysiology of its brain stem pathway. Encountering two cases of bradycardia and hypotension during surgery encouraged the authors to: (1) report these two cases and review similar reports in the relevant literature, (2) discuss the suggested mechanisms for such an event, and (3) report the result of a prospective cohort of precisely checked cases in a sister article, to remind the younger neurosurgical community of a possible and bothering even mortal, but avoidable complication in their everyday practice. Case Description: The first case was a 71-year-old male who developed bradycardia and hypotension while packing his large sella tursica with autologous fat after removing a large nonfunctional pituitary adenoma transsphenoidally to prevent cerebrospinal fluid leakage. The changes in his vital signs were detected and controlled rapidly. The second case was a 52-year-old female who underwent right pterional craniotomy for right clinoidal meningioma. She developed severe bradycardia and hypotension after skin closure completed and just when the subgaleal drain was connected to the aspirating bag and negative pressure maintained in the subgaleal region. Both cases could be managed successfully after on time detection of such life threatening complication and proper management. Conclusion: We do not intend only to add two new cases of TCR occurring in the perioperative period in neurosurgical practice, but we wish to raise the question: (a) what could be the predisposing factors for development of such issue for better handling of the problem and (b) stress upon careful continuous mapping of the vital signs during surgery and even till very late after operation. PMID:24233130

  19. Cholesteric Liquid Crystal Based Reflex Color Reflective Displays

    NASA Astrophysics Data System (ADS)

    Khan, Asad

    2012-02-01

    Bistable color cholesteric liquid crystal displays are unique LCDs that exhibit high reflectivity, good contrast, extremely low power operation, and are amenable to versatile roll-to-roll manufacturing. The display technology, now branded as Reflex has been in commercialized products since 1996. It has been the subject of extensive research and development globally by a variety of parties in both academic and industrial settings. Today, the display technology is in volume production for applications such as dedicated eWriters (Boogie Board), full color electronic skins (eSkin), and displays for smart cards. The flexibility comes from polymerization induced phase separation using unique materials unparalleled in any other display technology. The blend of monomers, polymers, cross linkers, and other components along with nematic liquid crystals and chiral dopants is created and processed in such ways so as to enable highly efficient manufactrable displays using ultra thin plastic substrates -- often as thin as 50?m. Other significant aspects include full color by stacking or spatial separation, night vision capability, ultra high resolution, as well as active matrix capabilities. Of particular note is the stacking approach of Reflex based displays to show full color. This approach for reflective color displays is unique to this technology. Owing to high transparency in wavelength bands outside the selective reflection band, three primarily color layers can be stacked on top of each other and reflect without interfering with other layers. This highly surprising architecture enables the highest reflectivity of any other reflective electronic color display technology. The optics, architecture, electro-topics, and process techniques will be discussed. This presentation will focus on the physics of the core technology and color, it's evolution from rigid glass based displays to flexible displays, development of products from the paradigm shifting concepts to consumer products and related markets. This is a development that spans a wide space of highly technical development and fundamental science to products and commercialization to enable the entry of the technology into consumer markets.

  20. The Muscle Stretch Reflex throughout the Menstrual Cycle

    PubMed Central

    Casey, Ellen; Hameed, Farah; Dhaher, Yasin Y.

    2014-01-01

    Introduction The significant sex-disparity in sports-related knee injuries may be due to underlying differences in motor control. While the development of sex-specific movement patterns is likely multi-factorial, this study specifically focuses on the potential modulatory role of sex hormones. Purpose To investigate the muscle stretch reflex (MSR) across the menstrual cycle. We hypothesized that the MSR would fluctuate throughout the menstrual cycle, and that the lowest response would correspond with peak concentrations of estrogen. Methods Nineteen healthy women ages 18–35 participated in this study: 8 eumenorrheic women and 11 women taking oral contraceptives. Serum estradiol and progesterone concentrations, anterior knee laxity (AKL) and the MSR response of the quadriceps muscles were measured three times during the menstrual cycle. Results The MSR response of the RF varied significantly across the menstrual cycle in both groups. Specifically, the RF MSR response was 2.4 times lower during the peri-ovulatory phase when compared to the luteal phase (P = 0.007). The same trend was seen in the VM, but this did not reach statistical significance (P = 0.070). The MSR response of the VL did not change significantly across the menstrual cycle (P = 0.494). A mixed model comparison did not show an association between endogenous concentrations of estradiol and progesterone, exposure to hormonal contraceptives or AKL and the MSR response for any muscle. Conclusions Our results demonstrate that the RF MSR response varies throughout the menstrual cycle with the lowest response around the time of ovulation. Additional research is needed to clarify the exact relationship between sex hormones, AKL and the MSR response and to determine the specific origin of the change along the monosynaptic reflex arc. PMID:24091990

  1. Projection neurons of the vestibulo-sympathetic reflex pathway.

    PubMed

    Holstein, Gay R; Friedrich, Victor L; Martinelli, Giorgio P

    2014-06-15

    Changes in head position and posture are detected by the vestibular system and are normally followed by rapid modifications in blood pressure. These compensatory adjustments, which allow humans to stand up without fainting, are mediated by integration of vestibular system pathways with blood pressure control centers in the ventrolateral medulla. Orthostatic hypotension can reflect altered activity of this neural circuitry. Vestibular sensory input to the vestibulo-sympathetic pathway terminates on cells in the vestibular nuclear complex, which in turn project to brainstem sites involved in the regulation of cardiovascular activity, including the rostral and caudal ventrolateral medullary regions (RVLM and CVLM, respectively). In the present study, sinusoidal galvanic vestibular stimulation was used to activate this pathway, and activated neurons were identified through detection of c-Fos protein. The retrograde tracer Fluoro-Gold was injected into the RVLM or CVLM of these animals, and immunofluorescence studies of vestibular neurons were conducted to visualize c-Fos protein and Fluoro-Gold concomitantly. We observed activated projection neurons of the vestibulo-sympathetic reflex pathway in the caudal half of the spinal, medial, and parvocellular medial vestibular nuclei. Approximately two-thirds of the cells were ipsilateral to Fluoro-Gold injection sites in both the RVLM and CVLM, and the remainder were contralateral. As a group, cells projecting to the RVLM were located slightly rostral to those with terminals in the CVLM. Individual activated projection neurons were multipolar, globular, or fusiform in shape. This study provides the first direct demonstration of the central vestibular neurons that mediate the vestibulo-sympathetic reflex. PMID:24323841

  2. Hip proprioceptors preferentially modulate reflexes of the leg in human spinal cord injury

    PubMed Central

    Onushko, Tanya; Hyngstrom, Allison

    2013-01-01

    Stretch-sensitive afferent feedback from hip muscles has been shown to trigger long-lasting, multijoint reflex responses in people with chronic spinal cord injury (SCI). These reflexes could have important implications for control of leg movements during functional activities, such as walking. Because the control of leg movement relies on reflex regulation at all joints of the limb, we sought to determine whether stretch of hip muscles modulates reflex activity at the knee and ankle and, conversely, whether knee and ankle stretch afferents affect hip-triggered reflexes. A custom-built servomotor apparatus was used to stretch the hip muscles in nine chronic SCI subjects by oscillating the legs about the hip joint bilaterally from 10° of extension to 40° flexion. To test whether stretch-related feedback from the knee or ankle would be affected by hip movement, patellar tendon percussions and Achilles tendon vibration were delivered when the hip was either extending or flexing. Surface electromyograms (EMGs) and joint torques were recorded from both legs. Patellar tendon percussions and Achilles tendon vibration both elicited reflex responses local to the knee or ankle, respectively, and did not influence reflex responses observed at the hip. Rather, the movement direction of the hip modulated the reflex responses local to the joint. The patellar tendon reflex amplitude was larger when the perturbation was delivered during hip extension compared with hip flexion. The response to Achilles vibration was modulated by hip movement, with an increased tonic component during hip flexion compared with extension. These results demonstrate that hip-mediated sensory signals modulate activity in distal muscles of the leg and appear to play a unique role in modulation of spastic muscle activity throughout the leg in SCI. PMID:23615544

  3. Serotonergic Modulation of the Trigeminocardiac Reflex Neurotransmission to Cardiac Vagal Neurons in the Nucleus Ambiguus

    PubMed Central

    Gorini, C.; Jameson, H. S.; Mendelowitz, D.

    2009-01-01

    Stimulation of the trigeminal nerve evokes a dramatic decrease in heart rate and blood pressure, and this reflex has generally been termed the trigeminocardiac reflex. A subset of the trigeminocardiac reflex is the diving reflex in which the nasal mucosa is stimulated with water or air-borne chemical irritants. Activation of the diving reflex evokes a pronounced bradycardia, mediated by increased parasympathetic cardiac activity, and is the most powerful autonomic reflex. However, exaggeration of this protective response could be detrimental and has been implicated in Sudden Infant Death Syndrome (SIDS). Despite the importance and strength of the trigeminocardiac reflex, there is little information about the cellular mechanisms and brain stem pathways that constitute this reflex. To address these issues, stimulation of trigeminal afferent fibers and the evoked excitatory postsynaptic currents were recorded in cardiac vagal neurons (CVNs) in an in vitro brain stem slice preparation. This synaptic pathway is robust and activation of the trigeminal pathway often evoked action potentials in CVNs. Application of the serotonin (5-HT) reuptake inhibitor citalopram significantly enhanced these responses. Consistent with the hypothesis this pathway is endogenously modulated by 5-HT receptors the 5-HT1A receptor antagonist, WAY 100635 inhibited, whereas the 5-HT2A/C receptor antagonist, ketanserin facilitated the excitatory neurotransmission to CVNs. The 5-HT1A receptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide increased, whereas the 5-HT2 receptor agonist, ?-methylserotonin maleate salt inhibited this reflex pathway. These results indicate stimulation of trigeminal fibers evokes a powerful excitatory and polysynaptic pathway to CVNs, and this pathway is endogenously modulated and differentially enhanced and depressed, by 5-HT1A and 5-HT2 receptors, respectively. PMID:19553488

  4. Serotonergic modulation of the trigeminocardiac reflex neurotransmission to cardiac vagal neurons in the nucleus ambiguus.

    PubMed

    Gorini, C; Jameson, H S; Mendelowitz, D

    2009-09-01

    Stimulation of the trigeminal nerve evokes a dramatic decrease in heart rate and blood pressure, and this reflex has generally been termed the trigeminocardiac reflex. A subset of the trigeminocardiac reflex is the diving reflex in which the nasal mucosa is stimulated with water or air-borne chemical irritants. Activation of the diving reflex evokes a pronounced bradycardia, mediated by increased parasympathetic cardiac activity, and is the most powerful autonomic reflex. However, exaggeration of this protective response could be detrimental and has been implicated in Sudden Infant Death Syndrome (SIDS). Despite the importance and strength of the trigeminocardiac reflex, there is little information about the cellular mechanisms and brain stem pathways that constitute this reflex. To address these issues, stimulation of trigeminal afferent fibers and the evoked excitatory postsynaptic currents were recorded in cardiac vagal neurons (CVNs) in an in vitro brain stem slice preparation. This synaptic pathway is robust and activation of the trigeminal pathway often evoked action potentials in CVNs. Application of the serotonin (5-HT) reuptake inhibitor citalopram significantly enhanced these responses. Consistent with the hypothesis this pathway is endogenously modulated by 5-HT receptors the 5-HT1A receptor antagonist, WAY 100635 inhibited, whereas the 5-HT2A/C receptor antagonist, ketanserin facilitated the excitatory neurotransmission to CVNs. The 5-HT1A receptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide increased, whereas the 5-HT2 receptor agonist, alpha-methylserotonin maleate salt inhibited this reflex pathway. These results indicate stimulation of trigeminal fibers evokes a powerful excitatory and polysynaptic pathway to CVNs, and this pathway is endogenously modulated and differentially enhanced and depressed, by 5-HT1A and 5-HT2 receptors, respectively. PMID:19553488

  5. Dynamic control of muscle stiffness and H reflex modulation during hopping and jumping in man.

    PubMed Central

    Dyhre-Poulsen, P; Simonsen, E B; Voigt, M

    1991-01-01

    1. The objective of the study was to evaluate the functional effects of reflexes on muscle mechanics during natural voluntary movements. The excitability of the H (Hoffmann) reflex was used as a measure of the excitability of the central component of the stretch reflex. 2. We recorded EMG, ground reaction forces and the H reflex in the soleus muscle in humans while landing from a downward jump, during drop jumping and during hopping. The movements were also recorded by high-speed cinematography. 3. The EMG pattern was adapted to the motor task. When landing the EMG in the soleus muscle and in the anterior tibial muscle showed preinnervation and alternating activity after touch down. When hopping there was little preinnervation in the soleus muscle, and the activity was initiated about 45 ms after touch down by a peak and continued unbroken until lift off. In the drop jumps the EMG pattern depended on the jumping style used by the subject. 4. The H reflex in the soleus muscle was strongly modulated in a manner appropriate to the requirements of the motor task. During landing from a downward jump the H reflex was low at touch down whereas while hopping it was high at touch down. During drop jumping it was variable and influenced by the jumping technique. 5. Muscle stiffness in the ankle joint was negative after touch down when landing, but always positive when hopping. 6. It is suggested that during landing the alternating EMG pattern after touch down was programmed and little influenced by reflexes. During hopping reflexes could contribute to the initial peak and the EMG during lift off. 7. The programmed EMG activity and the suppression of the H reflex while landing probably contribute to the development of the negative stiffness and change the muscles from a spring to a damping unit. PMID:1890636

  6. Trigemino-cardiac reflex as lethal mechanism in a suicidal fire death case.

    PubMed

    Rossi, Riccardo; Lodise, Maria; Lancia, Massimo; Bacci, Mauro; De-Giorgio, Fabio; Cascini, Fidelia

    2014-05-01

    In the vast majority of immediate fire deaths, the mechanism of death is inhalation of toxic gases (especially carbon monoxide), direct thermal injury, or neurogenic shock due to the redistribution of the body's blood volume produced by surface heat on the skin. We present a suicidal case that is unusual because the mechanism of immediate fire death could arguably be explained in terms of a primitive autonomic reflex/the trigemino-cardiac reflex. Although this reflex is well known to surgeons and anesthetists, with possible lethal consequences in the course of invasive surgical procedures on the head and neck region, it is much less familiar to forensic pathologists. PMID:24502511

  7. Subthreshold vestibular reflex effects in seated humans can contribute to soleus activation when combined with cutaneous inputs.

    PubMed

    Thomas, Kristen E; Bent, Leah R

    2013-01-01

    The integration of vestibular and somatosensory information for the control of lower limb musculature remains elusive. To determine whether a subthreshold vestibular input influences the cutaneous evoked response, the isometric EMG activity in the posturally inactive soleus muscles of 13 healthy, seated subjects was collected. Vestibular afferents were activated using galvanic vestibular stimulation (GVS; 1.8-2.5mA, 500ms), while percutaneous electrical stimulation was delivered to the distal tibial nerve (11ms train of 3 × 1.0 ms pulses, 200Hz) to activate foot sole skin afferents. GVS elicited responses in soleus both independently and when combined with cutaneous stimulation. The responses to the combined sensory input showed an interaction between the two sensory modalities to influence muscle activation. Of note is the presence of significant muscle modulation in the combined condition, where subthreshold vestibular inputs altered the outcome of the cutaneous reflex response. This finding has implications for individuals with sensory deficiency. In the case of an absent or deficient sensory modality, balance protective reflexes to maintain postural equilibrium may be enhanced with targeted sensory augmentation. PMID:23154186

  8. A Reevaluation of the Vestibulo-Ocular Reflex: New Ideas of its Purpose, Properties, Neural Substrate, and Disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. John; Brandt, Thomas

    1992-01-01

    Conventional views of the Vestibulo-Ocular Reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved-locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (less than 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  9. Evaluation of the diving reflex in response to nonterminal submersion of White Pekin ducks in water-based foam.

    PubMed

    Caputo, M P; Alphin, R L; Pritchett, E; Hougentogler, D P; Johnson, A L; Benson, E R; Patil, C

    2013-02-01

    The mass depopulation of production birds remains an effective means of controlling fast-moving, highly infectious diseases such as avian influenza and virulent Newcastle disease. Water-based fire-fighting foam is a conditionally approved method of depopulating floor-reared gallinaceous poultry such as chickens and turkeys; however, ducks have physiological mechanisms that may make them more resistant to this method of depopulation. The following experiment was designed to assess the physiological responses of White Pekin ducks to nonterminal submersion in water-based foam compared with water. The hypothesis of this experiment was that submersion of ducks in water or water-based foam would trigger the diving reflex and lead to bradycardia. All treatments led to pronounced bradycardia. Heart rate was not significantly different between treatments during the final 30 s of the 60-s treatment period. Heart rate dropped significantly faster for the water dip and foam dip treatments and rose significantly faster than the foam pour treatment after the termination of the 60-s treatment period. Duration of bradycardia approached significance for the foam pour treatment, leading to a longer duration of bradycardia compared with the water pour, water dip, and foam dip treatments. The results of this experiment demonstrated that apnea and bradycardia as a result of the diving reflex can occur as a result of submersion in foam, which may have an impact on the time it takes White Pekin ducks to reach unconsciousness and death during water-based foam depopulation. PMID:23300308

  10. Plasticity in the Rapid Escape Reflex of the Annelid Worm, Lumbriculus variegatus

    E-print Network

    Lybrand, Zane

    2012-10-19

    examined neural morphallaxis of the giant fiber pathway, which mediates rapid escape reflex behaviors in Lumbriculus. Electrophysiological recording techniques, immunohistochemistry, and transmission electron microscopy were used to demonstrate that prior...

  11. Collaborative and collective! Reflexive coordination and the dynamics of open innovation in clusters

    E-print Network

    Paris-Sud XI, Université de

    - including innovation-seeking partnerships in the early stages of cluster lifecycles. Key words: open1 Collaborative and collective! Reflexive coordination and the dynamics of open innovation: Economic geography increasingly conceptualises "innovation as a collective action" (Storper, 1996). However

  12. Analysis and restoration of a 1960s ear vacuum tube AM-FM reflex receiver

    E-print Network

    Golden, Adam J

    2004-01-01

    This thesis details the analysis, restoration, and evaluation of a 1960s era vacuum tube AM-FM reflex receiver. External influences such as tax laws necessitated clever designs to minimize the use of expensive vacuum tubes ...

  13. Reflex motion : choreographing the design of a performing arts center in Hadley, Massachusetts

    E-print Network

    Bernert, Julia M

    1987-01-01

    This thesis investigates an architectural design process through the techniques of intuitive drawing, conversation analysis, videotaping, site totems, and a reflexive journal. The design project is a performing arts complex ...

  14. Role of Autonomic Reflex Arcs in Cardiovascular Responses to Air Pollution Exposure

    EPA Science Inventory

    The body responds to environmental stressors by triggering autonomic reflexes in the pulmonary receptors, baroreceptors, and chemoreceptors to maintain homeostasis. Numerous studies have shown that exposure to various gases and airborne particles can alter the functional outcome ...

  15. Arnold’s nerve cough reflex: evidence for chronic cough as a sensory vagal neuropathy

    PubMed Central

    Gibson, Peter G.; Birring, Surinder S.

    2014-01-01

    Arnold’s nerve ear-cough reflex is recognised to occur uncommonly in patients with chronic cough. In these patients, mechanical stimulation of the external auditory meatus can activate the auricular branch of the vagus nerve (Arnold’s nerve) and evoke reflex cough. This is an example of hypersensitivity of vagal afferent nerves, and there is now an increasing recognition that many cases of refractory or idiopathic cough may be due to a sensory neuropathy of the vagus nerve. We present two cases where the cause of refractory chronic cough was due to sensory neuropathy associated with ear-cough reflex hypersensitivity. In both cases, the cough as well as the Arnold’s nerve reflex hypersensitivity were successfully treated with gabapentin, a treatment that has previously been shown to be effective in the treatment of cough due to sensory laryngeal neuropathy (SLN). PMID:25383210

  16. Arnold's nerve cough reflex: evidence for chronic cough as a sensory vagal neuropathy.

    PubMed

    Ryan, Nicole M; Gibson, Peter G; Birring, Surinder S

    2014-10-01

    Arnold's nerve ear-cough reflex is recognised to occur uncommonly in patients with chronic cough. In these patients, mechanical stimulation of the external auditory meatus can activate the auricular branch of the vagus nerve (Arnold's nerve) and evoke reflex cough. This is an example of hypersensitivity of vagal afferent nerves, and there is now an increasing recognition that many cases of refractory or idiopathic cough may be due to a sensory neuropathy of the vagus nerve. We present two cases where the cause of refractory chronic cough was due to sensory neuropathy associated with ear-cough reflex hypersensitivity. In both cases, the cough as well as the Arnold's nerve reflex hypersensitivity were successfully treated with gabapentin, a treatment that has previously been shown to be effective in the treatment of cough due to sensory laryngeal neuropathy (SLN). PMID:25383210

  17. REFLEX MODIFICATION AND THE DETECTION OF TOXICANT-INDUCED AUDITORY DYSFUNCTION

    EPA Science Inventory

    This report provides a reviev of reflex modification. eflex modification of the acoustic startle response is a technique that can provide rapid, objective and quantitative assessments of sensorimotor function. dvantages of this technique involve the ability to test animals rapidl...

  18. Spastic long-lasting reflexes of the chronic spinal rat studied in vitro.

    PubMed

    Li, Y; Harvey, P J; Li, X; Bennett, D J

    2004-05-01

    Over the months following sacral spinal cord transection in adult rats, a pronounced spasticity syndrome emerges in the affected tail musculature, where long-lasting muscle spasms can be evoked by low-threshold afferent stimulation (termed long-lasting reflex). To develop an in vitro preparation to examine the neuronal mechanisms underlying spasticity, we removed the whole sacrocaudal spinal cord of these spastic chronic spinal rats (>1 mo after S(2) sacral spinal transection) and maintained it in artificial cerebral spinal fluid in a recording chamber. The ventral roots were mounted on monopolar recording electrodes in grease, and the reflex responses to dorsal root stimulation were recorded and compared with the reflexes seen in the awake chronic spinal rat. When the dorsal roots were stimulated with a single pulse, a long-lasting reflex occurred in the ventral roots, with identical characteristics to the long-lasting reflex in the awake spastic rat tail. The reflex response was low threshold (T), short latency, long duration ( approximately 2 s), and enhanced by repeated stimulation. Brief high-frequency stimulation trains (0.5 s, 100 Hz, 1.5 x T) evoked even longer duration responses (5-10 s), with repeated bursts of activity that were similar to the repeated muscle spasms evoked in awake rats with stimulation trains or manual skin stimulation. Stimulation of a given dorsal root evoked long-lasting reflexes in both the ipsilateral and contralateral ventral roots. Long-lasting reflexes did not occur in the sacrocaudal spinal cord of acute spinal rats (S(2) transection), which is similar to the areflexia seen in awake acute spinal rats. However, long-lasting reflexes could be made to occur in the acute spinal rat by altering K(+) (7 mM) or Mg(2+) (0 mM) concentrations, or by application of high doses of the neuromodulators norepinephrine (NE, >20 microM) or serotonin (5-HT, >20 microM). In chronic spinal rats, much lower doses of these neuromodulators (0.1 microM) enhanced the long-lasting reflexes, suggesting a denervation supersensitivity to 5-HT and NE following injury. Higher doses of NE or 5-HT produced a paradoxical inhibition of the long-lasting reflexes. The high dose inhibition by NE was mimicked by the alpha(2)-adrenergic receptor agonist clonidine but not the alpha(1)-adrenergic receptor agonist methoxamine. In summary, the sacral spinal in vitro preparation offers a new approach to the study of spinal cord injury and analysis of antispastic drugs. PMID:15069101

  19. Transcranial electrical stimulation (Limoge's currents) potentiates the inhibition of righting reflex induced by droperidol in rats

    Microsoft Academic Search

    Claude Robert; Aymé Limoge; Luis Stinus

    1999-01-01

    The effects of transcranial electrical stimulation (TCES) on droperidol-treated rats were evaluated using the righting reflex latency (RRL) test. TCES (high frequency (HF)—166 kHz, intermittent—100 Hz current) delivered through three electrodes (a negative electrode placed between the eyebrows and positive electrodes located in the retro-mastoid region) was shown to potentiate the inhibition of righting reflex induced by droperidol. This potentiation

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

    PubMed

    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. PMID:23904494

  1. Amplitude Modulation of the Soleus H-Reflex in the Human During Walking and Standing

    Microsoft Academic Search

    C. Capaday; B. Stein

    Experiments were done to determine the amplitude of the mono- synaptically mediated H-reflex of the soleus muscle at various phases of the step cycle, using a computer-based analysis pro- cedure. In all subjects tested the amplitude of the H-reflex was strongly modulated in amplitude during the walking cycle and was highest during the stance phase. In many subjects the peak

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

    NASA Technical Reports Server (NTRS)

    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 the list, we hope to ultimately understand the mechanisms used by the brain in the expression of this behavior.

  3. Tonic vibration reflex in Holmes-Adie syndrome: an electrophysiological study

    PubMed Central

    Abbruzzese, Giovanni; Abbruzzese, Michele; Favale, Emilio; Ratto, Sandro

    1979-01-01

    The pathophysiological mechanisms underlying benign areflexia were studied in six patients with Holmes-Adie syndrome. No impairment of sensory conduction velocity of sural nerve was found. A normal tonic vibration reflex was obtained in all patients. H reflex was absent in five patients, but responses like F waves were recorded in three subjects. These findings suggest that muscle spindles are not affected and that spinal motoneurone excitability is normal. PMID:512669

  4. Sympathetic or reflex footpad swelling due to crystal-induced inflammation in the opposite foot

    Microsoft Academic Search

    Charles W. Denko; Mark Petricevic

    1978-01-01

    Sympathetic or reflex footpad swelling occurred in rats when several crystals known to be pathogenic in human joints or soft tissues were injected into the opposite footpad. Monosodium urate (MSU), calcium pyrophosphate dihydrate (CaPPD), hydroxyapatite, calcium oxalate (CaOx), and xanthine (X) suspension induced varying degrees of such reflex or sympathetic swelling. In the second cycle of crystal-induced swelling, the foot

  5. Stability of cough reflex sensitivity during viral upper respiratory tract infection (common cold).

    PubMed

    Dicpinigaitis, Peter V; Tibb, Amit S; Ramsey, David L; Carr, Andrew N; Poore, Cathy L

    2014-08-01

    Cough is among the symptoms most commonly associated with an acute, viral upper respiratory tract infection (URI), such as the common cold. Two previous studies incorporating capsaicin cough challenge methodology have demonstrated that cough reflex sensitivity is transiently enhanced during URI. These studies used single measurements of cough reflex sensitivity during the URI period. To our knowledge, no previous studies have included multiple measurements of cough reflex sensitivity to capsaicin during a URI to evaluate the stability of this measure during the acute viral illness. In the current methodological investigation, we performed capsaicin cough challenges in 42 subjects with URI who were otherwise healthy, adult, nonsmokers (25 female). Subjects were enrolled within 72 h of onset of illness and randomly assigned to 3 groups (n = 14 each) that underwent cough reflex sensitivity measurement (C2 and C5) at days 0 and 1 for group 1; days 2 and 3 for group 2; or days 4 and 5 for group 3. Each subject returned 4-8 weeks post-viral infection to establish a healthy baseline measurement (recovery). Our results support that cough reflex sensitivity to capsaicin, as measured by C5, is a sensitive measure that remains stable during 6 days of a URI. These results suggest that cough reflex sensitivity measures in the presence of a URI provide a sensitive and reproducible approach that could be used in future investigations seeking to test experimental antitussive therapies. PMID:24878421

  6. The Olivocochlear Reflex Strength and Cochlear Sensitivity are Independently Modulated by Auditory Cortex Microstimulation.

    PubMed

    Dragicevic, Constantino D; Aedo, Cristian; León, Alex; Bowen, Macarena; Jara, Natalia; Terreros, Gonzalo; Robles, Luis; Delano, Paul H

    2015-04-01

    In mammals, efferent projections to the cochlear receptor are constituted by olivocochlear (OC) fibers that originate in the superior olivary complex. Medial and lateral OC neurons make synapses with outer hair cells and with auditory nerve fibers, respectively. In addition to the OC system, there are also descending projections from the auditory cortex that are directed towards the thalamus, inferior colliculus, cochlear nucleus, and superior olivary complex. Olivocochlear function can be assessed by measuring a brainstem reflex mediated by auditory nerve fibers, cochlear nucleus neurons, and OC fibers. Although it is known that the OC reflex is activated by contralateral acoustic stimulation and produces a suppression of cochlear responses, the influence of cortical descending pathways in the OC reflex is largely unknown. Here, we used auditory cortex electrical microstimulation in chinchillas to study a possible cortical modulation of cochlear and auditory nerve responses to tones in the absence and presence of contralateral noise. We found that cortical microstimulation produces two different peripheral modulations: (i) changes in cochlear sensitivity evidenced by amplitude modulation of cochlear microphonics and auditory nerve compound action potentials and (ii) enhancement or suppression of the OC reflex strength as measured by auditory nerve responses, which depended on the intersubject variability of the OC reflex. Moreover, both corticofugal effects were not correlated, suggesting the presence of two functionally different efferent pathways. These results demonstrate that auditory cortex electrical microstimulation independently modulates the OC reflex strength and cochlear sensitivity. PMID:25663383

  7. A new method to determine reflex latency induced by high rate stimulation of the nervous system

    PubMed Central

    Karacan, Ilhan; Cakar, Halil I.; Sebik, Oguz; Yilmaz, Gizem; Cidem, Muharrem; Kara, Sadik; Türker, Kemal S.

    2014-01-01

    High rate stimulations of the neuromuscular system, such as continuous whole body vibration, tonic vibration reflex and high frequency electrical stimulation, are used in the physiological research with an increasing interest. In these studies, the neuronal circuitries underlying the reflex responses remain unclear due to the problem of determining the exact reflex latencies. We present a novel “cumulated average method” to determine the reflex latency during high rate stimulation of the nervous system which was proven to be significantly more accurate than the classical method. The classical method, cumulant density analysis, reveals the relationship between the two synchronously recorded signals as a function of the lag between the signals. The comparison of new method with the classical technique and their relative accuracy was tested using a computer simulation. In the simulated signals the EMG response latency was constructed to be exactly 40 ms. The new method accurately indicated the value of the simulated reflex latency (40 ms). However, the classical method showed that the lag time between the simulated triggers and the simulated signals was 49 ms. Simulation results illustrated that the cumulated average method is a reliable and more accurate method compared with the classical method. We therefore suggest that the new cumulated average method is able to determine the high rate stimulation induced reflex latencies more accurately than the classical method. PMID:25100978

  8. Velocity-dependent suppression of the soleus H-reflex during robot-assisted passive stepping.

    PubMed

    Masugi, Yohei; Kitamura, Taku; Kamibayashi, Kiyotaka; Ogawa, Tetsuya; Ogata, Toru; Kawashima, Noritaka; Nakazawa, Kimitaka

    2015-01-01

    The amplitude of the Hoffmann (H)-reflex in the soleus (Sol) muscle is known to be suppressed during passive stepping compared with during passive standing. The reduction of the H-reflex is not due to load-related afferent inputs, but rather to movement-related afferent inputs from the lower limbs. To elucidate the underlying neural mechanisms of this inhibition, we investigated the effects of the stepping velocity on the Sol H-reflex during robot-assisted passive stepping in 11 healthy subjects. The Sol H-reflexes were recorded during passive standing and stepping at five stepping velocities (stride frequencies: 14, 21, 28, 35, and 42 min(-1)) in the air. The Sol H-reflexes were significantly inhibited during passive stepping as compared with during passive standing, and reduced in size as the stepping velocity increased. These results indicate that the extent of H-reflex suppression increases with increasing movement-related afferent inputs from the lower limbs during passive stepping. The velocity dependence suggests that the Ia afferent inputs from lower-limb muscles around the hip and knee joints are most probably related to this inhibition. PMID:25449873

  9. Perception and gut reflexes induced by stimulation of gastrointestinal thermoreceptors in humans.

    PubMed Central

    Villanova, N; Azpiroz, F; Malagelada, J R

    1997-01-01

    1. Experimental studies in animals suggest the existence of thermoreceptors in the gastrointestinal tract. Our aim was to investigate the distribution and specificity of upper gut thermoreceptors in humans. 2. In healthy subjects, thermal stimulation of the stomach (n = 8) and the small intestine (n = 6) was produced by means of a thermostat, which recirculates water at adjusted temperatures through an ultrathin intraluminal bag. Progressively warm (42, 47 and 52 degrees C) and cold (32, 22 and 12 degrees C) stimuli of 3 min duration were alternately applied at 13 min intervals. Perception was scored on a scale of 0-6 and gastric tone responses were measured with a barostat. 3. Thermal stimuli induced specific responses: cold stimuli induced abdominal cold sensation and a reflex contraction of the stomach, whereas warm stimuli induced warm sensation and a reflex gastric relaxation. 4. Thermal stimuli induced similar stimulus-related perception in the stomach and small intestine (temperatures between 12 and 49.5 +/- 0.5 degrees C were tolerated). 5. The reflex responses were site specific. Warm and cold stimulation of the stomach induced gastric reflexes (76 +/- 26 ml isobaric expansion at 47 degrees C, and 68 +/- 10 ml contraction at 12 degrees C; P < 0.05 for both). However, only warm, not cold, stimulation of the intestine induced enterogastric reflexes. 6. These results indicate that in humans, warm and cold receptors are distributed along the gastrointestinal tract and project afferent input both into perception and reflex circuits with specific topographic organization. PMID:9234208

  10. Quantifying the deep tendon reflex using varying tendon indentation depths: applications to spasticity.

    PubMed

    Chardon, Matthieu K; Rymer, W Zev; Suresh, Nina L

    2014-03-01

    The deep tendon reflex (DTR) is often utilized to characterize the neuromuscular health of individuals because it is cheap, quick to implement, and requires limited equipment. However, DTR assessment is unreliable and assessor-dependent improve the reliability of the DTR assessment, we devised a novel standardization procedure. Our approach is based on the hypothesis that the neuromuscular state of a muscle changes systematically with respect to the indentation depth of its tendon. We tested the hypothesis by progressively indenting the biceps tendons on each side of nine hemiplegic stroke survivors to different depths, and then superimposing a series of brief controlled taps at each indentation depth to elicit a reflex response. Our results show that there exists a unique indentation depth at which reflex responses are consistently recorded (termed the Reflex Threshold) with increasing amplitude along increasing indentation depth. We further show that the reflex threshold depth is systematically smaller on the affected side of stroke survivors and that it is negatively correlated with the Modified Ashworth Score (VAF 70%). Our procedure also enables measurement of passive mechanical properties at the indentation location. In conclusion, our study shows that controlling for the indentation depth of the tendon of a muscle alters its reflex response predictably. Our novel device and method could be used to estimate neuromuscular changes in muscle (e.g., spasticity). Although some refinement is needed, this method opens the door to more reliable quantification of the DTR. PMID:24621852

  11. Proprioceptive neuropathy affects normalization of the H-reflex by exercise after spinal cord injury

    PubMed Central

    Ollivier-Lanvin, Karen; Keeler, Benjamin E.; Siegfried, Rachel; Houlé, John D.; Lemay, Michel A.

    2009-01-01

    The H-reflex habituates at relatively low frequency (10 Hz) stimulation in the intact spinal cord, but loss of descending inhibition resulting from spinal cord transection reduces this habituation. There is a return towards a normal pattern of low-frequency habituation in the reflex activity with cycling exercise of the affected hind limbs. This implies that repetitive passive stretching of the muscles in spinalized animals and the accompanying stimulation of large (Group I and II) proprioceptive fibers has modulatory effects on spinal cord reflexes after injury. To test this hypothesis, we induced pyridoxine neurotoxicity that preferentially affects large dorsal root ganglia neurons in intact and spinalized rats. Pyridoxine or saline injections were given twice daily (IP) for 6 weeks and half of the spinalized animals were subjected to cycling exercise during that period. After 6 weeks, the tibial nerve was stimulated electrically and recordings of M and H waves were made from interosseous muscles of the hind paw. Results show that pyridoxine treatment completely eliminated the H-reflex in spinal intact animals. In contrast, transection paired with pyridoxine treatment resulted in a reduction of the frequency-dependent habituation of the H-reflex that was not affected by exercise. These results indicate that normal Group I and II afferent input is critical to achieve exercise-based reversal of hyper-reflexia of the H-reflex after spinal cord injury. PMID:19913536

  12. Maintenance of constant arm position or force: reflex and volitional components in man.

    PubMed Central

    Colebatch, J G; McCloskey, D I

    1987-01-01

    1. Normal subjects, with closed eyes, attempted to keep constant either the force exerted at the wrist or the position of the wrist against an elastic load. The load was attached to the wrist 275 mm from the axis of rotation of the elbow joint. During recording, the far end of the elastic load was displaced slowly enough that it was not immediately perceived but far enough for perception to occur before its completion. 2. The over-all relation between wrist force and position for the two conditions was approximately linear and could be described in terms of effective stiffness. The effective stiffness for the constant-position task averaged 2.8 N/mm (210 N m/rad), while for the constant-force task the mean effective stiffness was -0.028 N/mm (-2.1 N m/rad), indicative of slight over-compensation. 3. Averaging the performance at the onset of the imposed disturbance indicated that the subjects' behaviour consisted of two parts: an initial, small-range response followed by a second phase over the remainder of the displacement. The transition corresponded to the subjects' threshold for detection of the disturbance. 4. The stiffness measured for the response prior to perception was taken as a measure which included the tonic stretch reflex. The stiffness was altered appropriately for the two tasks, being lower when the subjects tried to maintain the force exerted constant (average 1.1 N/mm, 83 N m/rad) than when they attempted to keep the position constant (average 2.3 N/mm, 170 N m/rad). A small degree of co-contraction occurred but could be dissociated from the stiffness changes. 5. Scaling the results allowed comparison of the initial stiffness with values for the decerebrate cat. When analysed in this way, the values recorded in man during the constant-position task were similar to those reported for short-range stiffness in the decerebrate cat. 6. The thresholds for detection of the disturbance were much lower than those reported for subjects with relaxed muscles. 7. The stretch reflex in man has a direct role in compensating for small disturbances during motor tasks. It may also function to improve detection of applied disturbances by magnifying the corresponding force change. Once the stimulus is perceived and voluntary intervention is possible, a greater contrast is seen between the subjects' performance of the two tasks. PMID:3681708

  13. The proboscis extension reflex to evaluate learning and memory in honeybees ( Apis mellifera): some caveats

    NASA Astrophysics Data System (ADS)

    Frost, Elisabeth H.; Shutler, Dave; Hillier, Neil Kirk

    2012-09-01

    The proboscis extension reflex (PER) is widely used in a classical conditioning (Pavlovian) context to evaluate learning and memory of a variety of insect species. The literature is particularly prodigious for honeybees ( Apis mellifera) with more than a thousand publications. Imagination appears to be the only limit to the types of challenges to which researchers subject honeybees, including all the sensory modalities and a broad diversity of environmental treatments. Accordingly, some remarkable insights have been achieved using PER. However, there are several challenges to evaluating the PER literature that warrant a careful and thorough review. We assess here variation in methods that makes interpretation of studies, even those researching the same question, tenuous. We suggest that the numerous variables that might influence experimental outcomes from PER be thoroughly detailed by researchers. Moreover, the influence of individual variables on results needs to carefully evaluated, as well as among two or more variables. Our intent is to encourage investigation of the influence of numerous variables on PER results.

  14. Preliminary investigation of absent nociceptive flexion reflex responses among more symptomatic women with fibromyalgia syndrome.

    PubMed

    Umeda, Masataka; Corbin, Lisa W; Maluf, Katrina S

    2013-09-01

    Fibromyalgia syndrome (FMS) is a widespread musculoskeletal pain condition with unclear physiologic mechanisms. The purpose of this investigation was to compare the responsiveness of nociceptive flexion reflex (NFR) pathways between women with and without FMS. A secondary purpose was to examine the influence of depression, fibromyalgia symptom severity, and cardiovascular health on NFR responses among women with FMS. Fifteen women with FMS and 14 healthy controls participated in an experimental session to assess NFR responses to sural nerve stimulation, resting mean arterial pressure (MAP) and heart rate (HR), and scores on the Beck Depression Inventory (BDI) and Fibromyalgia Impact Questionnaire (FIQ). NFR responses were successfully elicited from all healthy individuals, but only eight (53 %) of the women with FMS. These women did not differ in the minimum stimulus intensity required to elicit an NFR response compared to healthy controls (p ? 0.35). Further, these women had lower BDI (p = 0.04) and FIQ (p = 0.02) scores compared to women with FMS from whom NFR responses could not be elicited. Resting HR was higher in both groups of women with FMS compared to healthy individuals (p < 0.05), and MAP was strongly associated with NFR thresholds only among women with FMS (r = 0.88, p < 0.01). Findings from this preliminary investigation suggest that NFR pathways are impaired in women who are more severely impacted by symptoms of depression and fibromyalgia, potentially due to desensitization of NFR pathways with chronic autonomic arousal. PMID:23553516

  15. Artificial Balance: Restoration of the Vestibulo-Ocular Reflex in Humans with a Prototype Vestibular Neuroprosthesis

    PubMed Central

    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. PMID:24808890

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

    PubMed

    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. PMID:25076935

  17. Readaptation of the Vestibulo-Ocular Reflex Relieves the Mal De Debarquement Syndrome

    PubMed Central

    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. PMID:25076935

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

    PubMed

    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. PMID:24808890

  19. Gain of the triceps surae stretch reflex in decerebrate and spinal cats during postural and locomotor activities.

    PubMed Central

    Bennett, D J; De Serres, S J; Stein, R B

    1996-01-01

    1. The triceps surae (TS) stretch reflex was measured in decerebrate cats during crossed extensor stimulation and after spinalization during rhythmic locomotor activity induced by clonidine and manual perineal stimulation. The TS force in response to sinusoidal stretch was measured at a given contraction level before and after deafferentation, and the 'reflex force' was computed by subtracting these two responses. Reflex 'gain' was computed as the ratio of the reflex and deafferented force responses (a unitless estimate of the open loop feedback gain). 2. Prior to locomotion the spontaneous muscle activity was low (less than 15% of maximum), but the reflex gain was relatively high (close to 1.0 with a 5 Hz stretch). When locomotion commenced the reflex gain was markedly lowered when measured at the same contraction level as before locomotion (25% of the gain prior to locomotion). At higher contraction levels the reflex gain was not significantly increased. The reflex force and EMG responses to stretch increased with the contraction level, but their effect on the total reflex gain was cancelled by an associated increase in the intrinsic muscle stiffness. 3. In the decerebrate cat, during weak tonic contractions (spontaneous), the reflex gain was high and comparable with the gain in the resting spinal cat. However, with increased tonic contractions produced by crossed extensor stimulation the reflex gain dropped. At higher contraction levels the gain was not significantly different from the gain during spinal locomotion. 4. When the frequency of stretch was increased from 3 to 20 Hz, EMG responses to stretch increased, but the reflex force decreased, since a more fused contraction developed with the more frequent reflex activations. Overall, the reflex gain decreased with frequency in both spinal and decerebrate cats. The phase lag of the reflex force, relative to the intrinsic muscle force, increased with increasing frequency, due to reflex delays, with a 180 deg lag occurring between 12 and 18 Hz (tremor frequencies). The mean gain was significantly lower and the phase lag was significantly greater during locomotion than during tonic crossed extensor contractions, suggesting different reflex mechanisms. 5. In conclusion, during locomotion in spinal cats afferent feedback from low frequency ankle movements, similar to those occurring during the normal step cycle, reflexly produces a small but significant fraction of the extensor force (about a quarter of the stretch-related force modulation). This fraction is remarkably constant at the different contraction levels of the step cycle. Afferent feedback during higher frequency movement is less effective, minimizing the chance of instability and tremor. In contrast during tonic contractions afferent feedback produces half of the total muscle force during perturbations, clearly contributing to the maintenance of posture. PMID:8930848

  20. Reflex Control of Robotic Gait Using Human Walking Data

    PubMed Central

    Macleod, Catherine A.; Meng, Lin; Conway, Bernard A.; Porr, Bernd

    2014-01-01

    Control of human walking is not thoroughly understood, which has implications in developing suitable strategies for the retraining of a functional gait following neurological injuries such as spinal cord injury (SCI). Bipedal robots allow us to investigate simple elements of the complex nervous system to quantify their contribution to motor control. RunBot is a bipedal robot which operates through reflexes without using central pattern generators or trajectory planning algorithms. Ground contact information from the feet is used to activate motors in the legs, generating a gait cycle visually similar to that of humans. Rather than developing a more complicated biologically realistic neural system to control the robot's stepping, we have instead further simplified our model by measuring the correlation between heel contact and leg muscle activity (EMG) in human subjects during walking and from this data created filter functions transferring the sensory data into motor actions. Adaptive filtering was used to identify the unknown transfer functions which translate the contact information into muscle activation signals. Our results show a causal relationship between ground contact information from the heel and EMG, which allows us to create a minimal, linear, analogue control system for controlling walking. The derived transfer functions were applied to RunBot II as a proof of concept. The gait cycle produced was stable and controlled, which is a positive indication that the transfer functions have potential for use in the control of assistive devices for the retraining of an efficient and effective gait with potential applications in SCI rehabilitation. PMID:25347544

  1. Osseous choristoma in child with strong vomiting reflex.

    PubMed

    Yamamoto, Masae; Migita, Masashi; Ogane, Satoru; Narita, Masato; Yamamoto, Nobuharu; Takaki, Takashi; Matsuzaka, Kenichi; Shibahara, Takahiko

    2014-01-01

    Osseous lesions within soft tissue such as the tongue are extremely rare. Here, we report an osseous choristoma on the posterior portion of the tongue in a patient with a strong vomiting reflex. The patient was an 11-year-old boy who presented with the chief complaint of swelling on the posterior portion of the tongue. A pedunculated tumor 8-mm in diameter with distinct borders was observed slightly to the right of the midline of the dorsum of the tongue and slightly anterior to the circumvallate papillae. The clinical diagnosis was a right lingual circumvallate papilla fibroma. A further examination conducted under general anesthesia in July 2012 confirmed a pedunculated and solid mass in the area of the circumvallate papillae. As these results suggested a benign tumor, the mass was resected. Histopathological findings on harvested bone and fibrous connective tissue covered with a layer of squamous cells led to a diagnosis of osteoma. At 18 months postoperatively, there were no signs of recurrence. PMID:25477038

  2. Reflex (unloading) and (defensive capitulation) responses in human neck muscle.

    PubMed Central

    Corna, S; Ito, Y; von Brevern, M; Bronstein, A M; Gresty, M A

    1996-01-01

    1. We studied unloading and stretch responses in human neck muscle during manoeuvres in which the head pulled against a 2-3 kg weight which could be abruptly released or applied electromagnetically. 2. During head tracking in pitch, unloading of the weight induced inhibition of EMG in the contracting sternocleidomastoid at a mean latency of 24.9 ms in normal subjects and at 41 ms in bilateral labyrinthine-defective subjects, with antagonist (trapezius) excitation at 30.5 and 41.3 ms, respectively. During tracking in yaw, unloading induced inhibition in the contracting splenius capitis (SpC) at a mean latency of 20.4 ms in normal subjects and 25 ms in labyrinthine-defective subjects, with excitation in the antagonist SpC at 22.2 and 24 ms, respectively. 3. If subjects tried to resist an unexpected sideways tug on the head a burst occurred in the stretched SpC at a mean latency of 53.5 ms. When subjects relaxed there was excitation of the shortening of SpC at 75.9 ms, which assisted the imposed motion and is possibly a "defensive reflex". PMID:8910241

  3. Anatomic patterning in the expression of vestibulosympathetic reflexes

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; Yates, B. J.; McAllen, R. M.

    2000-01-01

    To investigate the possibility that expression of vestibulosympathetic reflexes (VSR) is related to a nerve's anatomic location rather than its target organ, we compared VSR recorded from the same type of postganglionic fiber [muscle vasoconstrictor (MVC)] located at three different rostrocaudal levels: hindlimb, forelimb, and face. Experiments were performed on chloralose-anesthetized cats, and vestibular afferents were stimulated electrically. Single MVC unit activity was extracted by spike shape analysis of few-fiber recordings, and unit discrimination was confirmed by autocorrelation. Poststimulus time histogram analysis revealed that about half of the neurons were initially inhibited by vestibular stimulation (type 1 response), whereas the other MVC fibers were initially strongly excited (type 2 response). MVC units with types 1 and 2 responses were present in the same nerve fascicle. Barosensitivity was equivalent in the two groups, but fibers showing type 1 responses fired significantly faster than those giving type 2 responses (0.29 +/- 0.04 vs. 0.20 +/- 0.02 Hz). Nerve fibers with type 1 responses were most common in the hindlimb (21 of 29 units) and least common in the face (2 of 11 units), the difference in relative proportion being significant (P < 0.05, chi(2) test). These results support the hypothesis that VSR are anatomically patterned.

  4. Methods of assessing vagus nerve activity and reflexes

    PubMed Central

    Chapleau, Mark W.; Sabharwal, Rasna

    2015-01-01

    The methods used to assess cardiac parasympathetic (cardiovagal) activity and its effects on the heart in both humans and animal models are reviewed. Heart rate (HR)-based methods include measurements of the HR response to blockade of muscarinic cholinergic receptors (parasympathetic tone), beat-to-beat HR variability (HRV) (parasympathetic modulation), rate of post-exercise HR recovery (parasympathetic reactivation), and reflex-mediated changes in HR evoked by activation or inhibition of sensory (afferent) nerves. Sources of excitatory afferent input that increase cardiovagal activity and decrease HR include baroreceptors, chemoreceptors, trigeminal receptors, and subsets of cardiopulmonary receptors with vagal afferents. Sources of inhibitory afferent input include pulmonary stretch receptors with vagal afferents and subsets of visceral and somatic receptors with spinal afferents. The different methods used to assess cardiovagal control of the heart engage different mechanisms, and therefore provide unique and complementary insights into underlying physiology and pathophysiology. In addition, techniques for direct recording of cardiovagal nerve activity in animals; the use of decerebrate and in vitro preparations that avoid confounding effects of anesthesia; cardiovagal control of cardiac conduction, contractility, and refractoriness; and noncholinergic mechanisms are described. Advantages and limitations of the various methods are addressed, and future directions are proposed. PMID:20577901

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

    PubMed

    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. PMID:11349781

  6. Investigation of fundo-antral reflex in human beings

    PubMed Central

    Rao, Satish SC; Kumar, Anjana; Harris, Brent; Brown, Bruce; Schulze, Konrad S

    2005-01-01

    AIM: To examine the sensory and motor response(s) of the stomach following fundic distention and to assess whether cholinergic mechanisms influence these responses. METHODS: Fundic tone, gastric sensory responses and antral motility were evaluated in eight healthy volunteers after a probe with two sensors was placed in the antrum and a highly compliant balloon in the fundus. Isobaric balloon distentions were performed with a barostat. Study was repeated in six volunteers after intravenous atropine was given. RESULTS: Fundic distention induced large amplitude antral contractions in all subjects. The area under the curve was higher (P<0.05) during fundic distention. First sensation was reported at 12±4 mmHg, moderate sensation at 18±4 mmHg and discomfort at 21±4 mmHg. Discomfort was associated with a decrease in antral motility. After atropine was given, the area under the curve of pressure waves and fundic tone decreased (P<0.05). Sensory thresholds were not affected. CONCLUSIONS: Fundic balloon distention induces an antral motor response, the fundo-antral reflex, which in part may be mediated by cholinergic mechanisms. PMID:16425364

  7. The human vestibulo-ocular reflex during linear locomotion

    NASA Technical Reports Server (NTRS)

    Moore, S. T.; Hirasaki, E.; Raphan, T.; Cohen, B.

    2001-01-01

    During locomotion, there is a translation and compensatory rotation of the head in both the vertical and horizontal planes. During moderate to fast walking (100 m/min), vertical head translation occurs at the frequency of stepping (2 Hz) and generates peak linear acceleration of 0.37 g. Lateral head translation occurs at the stride frequency (1 Hz) and generates peak linear acceleration of 0.1 g. Peak head pitch and yaw angular velocities are approximately 17 degrees/s. The frequency and magnitude of these head movements are within the operational range of both the linear and angular vestibulo-ocular reflex (IVOR and aVOR). Vertical eye movements undergo a phase reversal from near to far targets. When viewing a far (>1 m) target, vertical eye velocity is typical of an aVOR response; that is, it is compensatory for head pitch. At close viewing distances (<1 m), vertical eye velocity is in phase with head pitch and is compensatory for vertical head translation, suggesting that the IVOR predominantly generates the eye movement response. Horizontal head movements during locomotion occur at the stride frequency of 1 Hz, where the IVOR gain is low. Horizontal eye movements are compensatory for head yaw at all viewing distances and are likely generated by the aVOR.

  8. Reflexive obstacle avoidance for kinematically-redundant manipulators

    NASA Technical Reports Server (NTRS)

    Karlen, James P.; Thompson, Jack M., Jr.; Farrell, James D.; Vold, Havard I.

    1989-01-01

    Dexterous telerobots incorporating 17 or more degrees of freedom operating under coordinated, sensor-driven computer control will play important roles in future space operations. They will also be used on Earth in assignments like fire fighting, construction and battlefield support. A real time, reflexive obstacle avoidance system, seen as a functional requirement for such massively redundant manipulators, was developed using arm-mounted proximity sensors to control manipulator pose. The project involved a review and analysis of alternative proximity sensor technologies for space applications, the development of a general-purpose algorithm for synthesizing sensor inputs, and the implementation of a prototypical system for demonstration and testing. A 7 degree of freedom Robotics Research K-2107HR manipulator was outfitted with ultrasonic proximity sensors as a testbed, and Robotics Research's standard redundant motion control algorithm was modified such that an object detected by sensor arrays located at the elbow effectively applies a force to the manipulator elbow, normal to the axis. The arm is repelled by objects detected by the sensors, causing the robot to steer around objects in the workspace automatically while continuing to move its tool along the commanded path without interruption. The mathematical approach formulated for synthesizing sensor inputs can be employed for redundant robots of any kinematic configuration.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  10. Triceps surae stretch reflex modulation after a mechanically evoked ankle dorsiflexion during the swing phase of human running.

    PubMed

    Scohier, Mikael; De Jaeger, Dominique; Schepens, Benedicte

    2014-10-01

    The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s-1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion. We measured the electromyographic activity of the soleus, medial and lateral gastrocnemii just after the perturbation to evaluate the triceps surae stretch reflex. Similar perturbations were also delivered at rest. Our results showed that the stretch reflex was suppressed during the swing phase of running, except in late swing where a late reflex response was observed. At rest, all triceps surae muscles showed an early reflex response to stretch. Our findings suggest that the triceps surae short/medium-latency stretch reflex cannot be evoked during swing phase and thus cannot contribute to the control of the locomotor pattern after aperturbation during this phase. PMID:24718966

  11. sEMG during Whole-Body Vibration Contains Motion Artifacts and Reflex Activity

    PubMed Central

    Lienhard, Karin; Cabasson, Aline; Meste, Olivier; Colson, Serge S.

    2015-01-01

    The purpose of this study was to determine whether the excessive spikes observed in the surface electromyography (sEMG) spectrum recorded during whole-body vibration (WBV) exercises contain motion artifacts and/or reflex activity. The occurrence of motion artifacts was tested by electrical recordings of the patella. The involvement of reflex activity was investigated by analyzing the magnitude of the isolated spikes during changes in voluntary background muscle activity. Eighteen physically active volunteers performed static squats while the sEMG was measured of five lower limb muscles during vertical WBV using no load and an additional load of 33 kg. In order to record motion artifacts during WBV, a pair of electrodes was positioned on the patella with several layers of tape between skin and electrodes. Spectral analysis of the patella signal revealed recordings of motion artifacts as high peaks at the vibration frequency (fundamental) and marginal peaks at the multiple harmonics were observed. For the sEMG recordings, the root mean square of the spikes increased with increasing additional loads (p < 0.05), and was significantly correlated to the sEMG signal without the spikes of the respective muscle (r range: 0.54 - 0.92, p < 0.05). This finding indicates that reflex activity might be contained in the isolated spikes, as identical behavior has been found for stretch reflex responses evoked during direct vibration. In conclusion, the spikes visible in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activity. Key points The spikes observed in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activity The motion artifacts are more pronounced in the first spike than the following spikes in the sEMG spectrum Reflex activity during WBV exercises is enhanced with an additional load of approximately 50% of the body mass PMID:25729290

  12. Propranolol, but not naloxone, enhances spinal reflex bladder activity and reduces pudendal inhibition in cats.

    PubMed

    Rogers, Marc J; Xiao, Zhiying; Shen, Bing; Wang, Jicheng; Schwen, Zeyad; Roppolo, James R; de Groat, William C; Tai, Changfeng

    2015-01-01

    This study examined the role of ?-adrenergic and opioid receptors in spinal reflex bladder activity and in the inhibition induced by pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS). Spinal reflex bladder contractions were induced by intravesical infusion of 0.25% acetic acid in ?-chloralose-anesthetized cats after an acute spinal cord transection (SCT) at the thoracic T9/T10 level. PNS or TNS at 5 Hz was applied to inhibit these spinal reflex contractions at 2 and 4 times the threshold intensity (T) for inducing anal or toe twitch, respectively. During a cystrometrogram (CMG), PNS at 2T and 4T significantly (P < 0.05) increased bladder capacity from 58.0 ± 4.7% to 85.8 ± 10.3% and 96.5 ± 10.7%, respectively, of saline control capacity, while TNS failed to inhibit spinal reflex bladder contractions. After administering propranolol (3 mg/kg iv, a ??/??-adrenergic receptor antagonist), the effects of 2T and 4T PNS on bladder capacity were significantly (P < 0.05) reduced to 64.5 ± 9.5% and 64.7 ± 7.3%, respectively, of the saline control capacity. However, the residual PNS inhibition (about 10% increase in capacity) was still statistically significant (P < 0.05). Propranolol treatment also significantly (P = 0.0019) increased the amplitude of bladder contractions but did not change the control bladder capacity. Naloxone (1 mg/kg iv, an opioid receptor antagonist) had no effect on either spinal reflex bladder contractions or PNS inhibition. At the end of experiments, hexamethonium (10 mg/kg iv, a ganglionic blocker) significantly (P < 0.05) reduced the amplitude of the reflex bladder contractions. This study indicates an important role of ??/??-adrenergic receptors in pudendal inhibition and spinal reflex bladder activity. PMID:25394827

  13. Conditioning-specific reflex modification occurs when an unconditionedresponse(UR)ismodifiedinthe absence

    E-print Network

    , Pineda, & Buck, 2000), and can be generalized from electrodermal stimulation to air puff (Buck, Seager stimulation and has since been repli- cated by Wikgren and colleagues using air puff (Wikgren & Korhonen, 2001 puff study (Clark, Zhang, & Lavond, 1992) but did not attribute the increase to CS­US pairings because

  14. Role of adenosine A{sub 2A} receptor signaling in the nicotine-evoked attenuation of reflex cardiac sympathetic control

    SciTech Connect

    El-Mas, Mahmoud M., E-mail: mahelm@hotmail.com; El-gowilly, Sahar M.; Fouda, Mohamed A.; Saad, Evan I.

    2011-08-01

    Baroreflex dysfunction contributes to increased cardiovascular risk in cigarette smokers. Given the importance of adenosinergic pathways in baroreflex control, the hypothesis was tested that defective central adenosinergic modulation of cardiac autonomic activity mediates the nicotine-baroreflex interaction. Baroreflex curves relating changes in heart rate (HR) to increases or decreases in blood pressure (BP) evoked by i.v. doses (1-16 {mu}g/kg) of phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious rats; slopes of the curves were taken as measures of baroreflex sensitivity (BRS). Nicotine (25 and 100 {mu}g/kg i.v.) dose-dependently reduced BRS{sub SNP} in contrast to no effect on BRS{sub PE}. BRS{sub SNP} was also attenuated after intracisternal (i.c.) administration of nicotine. Similar reductions in BRS{sub SNP} were observed in rats pretreated with atropine or propranolol. The combined treatment with nicotine and atropine produced additive inhibitory effects on BRS, an effect that was not demonstrated upon concurrent exposure to nicotine and propranolol. BRS{sub SNP} was reduced in preparations treated with i.c. 8-phenyltheophylline (8-PT, nonselective adenosine receptor antagonist), 8-(3-Chlorostyryl) caffeine (CSC, A{sub 2A} antagonist), or VUF5574 (A{sub 3} antagonist). In contrast, BRS{sub SNP} was preserved after blockade of A{sub 1} (DPCPX) or A{sub 2B} (alloxazine) receptors or inhibition of adenosine uptake by dipyridamole. CSC or 8-PT abrogated the BRS{sub SNP} depressant effect of nicotine whereas other adenosinergic antagonists were without effect. Together, nicotine preferentially impairs reflex tachycardia via disruption of adenosine A{sub 2A} receptor-mediated facilitation of reflex cardiac sympathoexcitation. Clinically, the attenuation by nicotine of compensatory sympathoexcitation may be detrimental in conditions such as hypothalamic defense response, posture changes, and ventricular rhythms. - Research Highlights: > The role of central adenosinergic sites in the nicotine-baroreflex interaction was investigated. > Inhibition of reflex sympathoinhibition mediates the BRS depressant action of nicotine. > Nicotine preferentially impairs reflex tachycardia via disruption of adenosine A{sub 2A} signaling. > The attenuation by nicotine of reflex sympathetic activity is clinically important.

  15. Trigeminocardiac reflex in neurosurgical practice: An observational prospective study

    PubMed Central

    Etezadi, Farhad; Orandi, Amir Ali; Orandi, Amir Hosein; Najafi, Atabak; Amirjamshidi, Abbas; Pourfakhr, Pejman; Khajavi, Mohammad Reza; Abbassioun, Kazem

    2013-01-01

    Background: Considering wide variations regarding the incidence of trigeminocardiac reflex (TCR) during cranial neurosurgical procedures, and paucity of reliable data, we intended to design a prospective study to determine the incidence of TCR in patients undergoing standard general anesthesia for surgery of supra/infra-tentorial cranial and skull base lesions. Methods: A total of 190 consecutive patients candidate for elective surgery of supra-tentorial, infra-tentorial, and skull base lesions were enrolled. All the patients were operated in the neurosurgical operating room of a university-affiliated teaching hospital. All surgeries were performed using sufficient depth of anesthesia achieved by titration of propofol–alfentanil mixture, adjusted according to target Cerebral State Index (CSI) values (40-60). All episodes of bradycardia and hypotension indicating the occurrence of TCR during the surgery (sudden decrease of more than 20% from the previous level) were recorded. Results: Four patients, two female and two male, developed episodes of TCR during surgery (4/190; 2.1%). Three patients showed one episode of TCR just at the end of operation when the skin sutures were applied while CSI values were 70-77 and in the last case, when small tumor samples were taken from just beneath the lateral wall of the cavernous sinus TCR episode was seen while the CSI value was 51. Conclusion: TCR is a rare phenomenon during brain surgeries when patient is anesthetized using standard techniques. Keeping the adequate depth of anesthesia using CSI monitoring method may be an advisable strategy during whole period of a neurosurgical procedure. PMID:24083052

  16. An anomalous vagorenal reflex pathway in the cat.

    PubMed

    Calaresu, F R; Knuepfer, M M; Ciriello, J; Stella, A

    1985-02-01

    Although physiological investigations support the view that the innervation to the kidney is primarily sympathetic in origin, there is anatomic evidence suggesting direct vagal projections to the kidney. We examined electrophysiologically the possibility that neural connections exist between the cervical vagus and renal nerves. Electrical stimulation of the peripheral segment of the cut cervical vagus evoked electrical activity in the central segment of cut renal nerve of chloralose-anesthetized, paralyzed cats. The evoked potentials (vagorenal responses) displayed components with peak latencies of about 50, 120, and 500 ms. Another peak at about 175 ms was also seen in some cases. In addition, a period of postexcitatory depression occurred between approximately 180 and 400 ms after delivery of the stimulus. Evoked responses were recorded in the contralateral as well as the ipsilateral renal nerves. In contrast, stimulation of the central cut end of renal nerves did not elicit responses in the cervical vagus. Vagorenal responses were not altered by cutting the subdiaphragmatic vagus indicating that the abdominal vagus was not involved in this response. Electrical activity in renal nerves elicited by vagal stimulation could be eliminated by either ganglionic blockade or by cutting or cooling the splanchnic nerves. Finally, supraspinal ischemia abolished the vagorenal response. These data suggest that a vagorenal reflex pathway exists and that the potentials recorded in renal nerves are due to activation of aberrant sensory fibers traveling from the peripheral segment of the cut cervical vagus to the central nervous system, where they excite a sympathetic efferent pathway to the kidney. PMID:3967712

  17. Activation of the anti-inflammatory reflex blocks lipopolysaccharide-induced decrease in synaptic inhibition in the temporal cortex of the rat.

    PubMed

    Garcia-Oscos, Francisco; Peña, David; Housini, Mohammad; Cheng, Derek; Lopez, Diego; Cuevas-Olguin, Roberto; Saderi, Nadia; Salgado Delgado, Roberto; Galindo Charles, Luis; Salgado Burgos, Humberto; Rose-John, Stefan; Flores, Gonzalo; Kilgard, Michael P; Atzori, Marco

    2015-06-01

    Stress is a potential trigger for a number of neuropsychiatric conditions, including anxiety syndromes and schizophrenic psychoses. The temporal neocortex is a stress-sensitive area involved in the development of such conditions. We have recently shown that aseptic inflammation and mild electric shock shift the balance between synaptic excitation and synaptic inhibition in favor of the former in this brain area (Garcia-Oscos et al., 2012), as well as in the prefrontal cortex (Garcia-Oscos et al., 2014). Given the potential clinical importance of this phenomenon in the etiology of hyperexcitable neuropsychiatric illness, this study investigates whether inactivation of the peripheral immune system by the "anti-inflammatory reflex" would reduce the central response to aseptic inflammation. For a model of aseptic inflammation, this study used i.p. injections of the bacterial toxin lipopolysaccharide (LPS; 5 µM) and activated the anti-inflammatory reflex either pharmacologically by i.p. injections of the nicotinic ?7 receptor agonist PHA543613 or physiologically through electrical stimulation of the left vagal nerve (VNS). Patch-clamp recording was used to monitor synaptic function. Recordings from LPS-injected Sprague Dawley rats show that activation of the anti-inflammatory reflex either pharmacologically or by VNS blocks or greatly reduces the LPS-induced decrease of the synaptic inhibitory-to-excitatory ratio and the saturation level of inhibitory current input-output curves. Given the ample variety of pharmacologically available ?7 nicotinic receptor agonists as well as the relative safety of clinical VNS already approved by the FDA for the treatment of epilepsy and depression, our findings suggest a new therapeutic avenue in the treatment of stress-induced hyperexcitable conditions mediated by a decrease in synaptic inhibition in the temporal cortex. © 2015 Wiley Periodicals, Inc. PMID:25626997

  18. Development of a cardiopulmonary mathematical model incorporating a baro-chemoreceptor reflex control system.

    PubMed

    Lin, Jinhuai; Ngwompo, Roger F; Tilley, Derek G

    2012-10-01

    This article describes the development of a comprehensive mathematical model of the human cardiopulmonary system that combines the respiratory and cardiovascular systems and their associated autonomous nervous control actions. The model is structured to allow the complex interactions between the two systems and the responses of the combined system to be predicted under different physiological conditions. The cardiovascular system model contains 13 compartments, including the heart chambers operating as a pump and the blood vessels represented as distensible tubes configured in a serial and parallel arrangement. The accurate representation of the hemodynamics in the system and the good fit to published pressure and flow waveforms gave confidence in the modelling approach adopted for the cardiovascular system prior to the incorporation of the baroreflex control and the respiratory models. An improved baroreceptor reflex model is developed in this research, incorporating afferent, central and efferent compartments. A sigmoid function is included in the efferent compartment to produce sympathetic and parasympathetic nerve outflow to the effector sites. The baroreflex action is modelled using physiological data, its interaction with the chemoreflex control is explained and the simulation results presented show the ability of the model to predict the static and dynamic hemodynamic responses to environmental disturbances. A previously published respiratory model that includes the mechanics of breathing, gas exchange process and the regulation of the system is then combined with the cardiovascular model to form the cardiopulmonary model. Through comparison with published data, the cardiopulmonary model with the baro-chemoreflex control is validated during hypoxia and hypercapnia. The percentage difference between the predicted and measured changes in the heart rates and the mean arterial pressures are within 3% in both cases. The total peripheral resistance correlates well for hypoxia but is less good for hypercapnia, where the predicted change from normal condition is around 7% compared with a measured change of 23%. An example showing the application of the proposed model in sport science is also included. PMID:23157080

  19. Interaction of semicircular canal stimulation with carotid baroreceptor reflex control of heart rate

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.

    1998-01-01

    The carotid-cardiac baroreflex contributes to the prediction of orthostatic tolerance; experimental attenuation of the reflex response leads to orthostatic hypotension in humans and animals. Anecdotal observations indicate that rotational head movements about the vertical axis of the body can also induce orthostatic bradycardia and hypotension through increased parasympathetic activity. We therefore measured the chronotropic response to carotid baroreceptor stimulation in 12 men during varying conditions of vestibulo-oculomotor stimulation to test the hypothesis that stimulation of the semicircular canals associated with head movements in the yaw plane inhibits cardioacceleration through a vagally mediated baroreflex. Carotid-cardiac baroreflex response was assessed by plotting R-R intervals (ms) at each of 8 neck pressure steps with their respective carotid distending pressures (mmHg). Calculated baroreflex gain (maximal slope of the stimulus-response relationship) was measured under 4 experimental conditions: 1) sinusoidal whole-body yaw rotation of the subject in the dark without visual fixation (combined vestibular-oculomotor stimulation); 2) yaw oscillation of the subject while tracking a small head-fixed light moving with the subject (vestibular stimulation without eye movements); 3) subject stationary while fixating on a small light oscillating in yaw at the same frequency, peak acceleration, and velocity as the chair (eye movements without vestibular stimulation); and 4) subject stationary in the dark (no eye or head motion). Head motion alone and with eye movement reduced baseline baroreflex responsiveness to the same stimulus by 30%. Inhibition of cardioacceleration during rotational head movements may have significant impact on functional performance in aerospace environments, particularly in high-performance aircraft pilots during high angular acceleration in aerial combat maneuvers or in astronauts upon return from spaceflight who already have attenuated baroreflex functions.

  20. Development of metabolic shifts in structures of the spinal reflex arc in rats after space flight.

    PubMed

    Portugalov, V V; Gorbunova, A V; Petrova, N V

    1979-01-01

    The stage of structures of the spinal reflex arc was studied by methods of quantitative cytochemistry in rats after orbital space flights lasting 19.5 and 22.5 days; the RNA and cytoplasmic protein content was determined in spinal motoneurons and sensory neurons of the spinal ganglia, the composition of soluble proteins of the gray and white matter of the spinal cord and spinal ganglia was determined; the lactate dehydrogenase (LD) isozyme spectrum also was investigated in the spinal ganglia and muscles of the hind limbs. A decrease in the content of cytoplasmic proteins in the spinal motoneurons and neurons of the spinal ganglia and a decrease in the content of water-soluble proteins in the gray and white matter of the spinal cord were found 5-11 h after space flight lasting 19.5 days and during the first day after a space flight lasting 22.5 days. Significant changes in the activity of isozyme fractions LD1 and LD2 were found in homogenates of the spinal ganglia. On the 1st and 2nd days after flight the LD isozyme spectrum of the soleus muscle changed from "cardiac" to "intermediate" type. The changes discovered were evidently the result of functional underactivity of the skeletal muscles under conditions of weightlessness. An increase in the RNA content in the sensory and motor neurons and an increase in the content of water-soluble proteins in the gray matter of the spinal cord were found 25-27 days after the end of the space flights, probably a manifestation of readaptation of the animals to terrestrial conditions. PMID:95099

  1. Role of medullary GABA signal transduction on parasympathetic reflex vasodilatation in the lower lip.

    PubMed

    Kawakami, So; Izumi, Hiroshi; Masaki, Eiji; Kuchiiwa, Satoshi; Mizuta, Kentaro

    2012-02-01

    In the orofacial area, noxious stimulation of the orofacial structure in the trigeminal region evokes parasympathetic reflex vasodilatation, which occurs via the trigeminal spinal nucleus (Vsp) and the inferior/superior salivatory nucleus (ISN/SSN). However, the neurotransmitter involved in the inhibitory synaptic inputs within these nuclei has never been described. This parasympathetic reflex vasodilatation is suppressed by GABAergic action of volatile anesthetics, such as isoflurane, sevoflurane, and halothane, suggesting that medullary GABAergic mechanism exerts its inhibitory effect on the parasympathetic reflex via an activation of GABA receptors. The aim of the present study was to determine the role of GABA(A) and GABA(B) receptors in the Vsp and the ISN in regulating the lingual nerve (LN)-evoked parasympathetic reflex vasodilatation in the lower lip. Under urethane anesthesia (1g/kg), change in lower lip blood flow elicited by electrical stimulation of the LN was recorded in cervically vago-sympathectomized rats. Microinjection of GABA (10 ?M; 0.3 ?l/site) into the Vsp or the ISN significantly and reversibly attenuated the LN-evoked parasympathetic reflex vasodilatation. Microinjection of the GABA(A) receptor-selective agonist muscimol (100 ?M; 0.3 ?l/site) or the GABA(B) receptor-selective agonist baclofen (100 ?M; 0.3 ?l/site) into the Vsp or the ISN significantly and irreversibly reduced this reflex vasodilatation, and these effects were attenuated by pretreatment with microinjection of each receptor-selective antagonists [GABA(A) receptor selective antagonist bicuculline methiodide (1mM; 0.3 ?l/site) or GABA(B) receptor selective antagonist CGP-35348 (1mM; 0.3 ?l/site)] into the Vsp or the ISN. Microinjection of these antagonists alone into the Vsp or the ISN had no significant effect on this reflex vasodilatation. In addition, microinjection (0.3 ?l/site) of the mixture of muscimol (100 ?M) and baclofen (100 ?M) into the Vsp or the ISN also significantly reduced this reflex vasodilatation. These results suggest that medullary GABA signal transduction inhibits the parasympathetic reflex vasodilatation in the rat lower lip via GABA(A) and GABA(B) receptors in the Vsp and the ISN. PMID:22226507

  2. Reflex Modulation is Linked to the Orientation of Arm Mechanics Relative to the Environment

    PubMed Central

    Krutky, Matthew A.; Ravichandran, Vengateswaran J.; Trumbower, Randy D.; Perreault, Eric J.

    2009-01-01

    To successfully complete a motor task, it is necessary to control not only the kinematics and dynamics of a limb, but also its mechanical properties. In a multijoint task such as the control of arm posture, limb mechanics are directional, resisting external disturbances more effectively in certain directions than others. It has been demonstrated that feedforward neuromotor pathways can regulate these directional characteristics of the arm to compensate for changes in the mechanical properties of the environment. However, it is unclear if spinal reflex pathways exhibit a similar specificity. The present results suggest that the sensitivity of the human stretch reflex also can be tuned to adapt the mechanical properties of the arm in a task appropriate manner. We hypothesized that the orientation of arm mechanics relative to the mechanical properties of the environment would influence reflex adaptation. Two destabilizing environments, oriented relative to the mechanical properties of the arm, were used to test this hypothesis. These environments were simulated using a 3 degrees of freedom (DOF) robot, which also was used to perturb arm posture. The resulting reflexes, assessed by electromyograms recorded from 8 muscles, were found to modulate in accordance with how the environmental instability was oriented relative to the mechanical properties of the arm. Our results suggest that stretch sensitive reflexes throughout the arm are modulated in a coordinated manner corresponding to the orientation of arm mechanics relative to the environment. PMID:19163926

  3. Endothelial nitric oxide synthase mediates the nitric oxide component of reflex cutaneous vasodilatation during dynamic exercise in humans.

    PubMed

    McNamara, Tanner C; Keen, Jeremy T; Simmons, Grant H; Alexander, Lacy M; Wong, Brett J

    2014-12-01

    Recent data suggests neuronal nitric oxide synthase (nNOS) mediates the NO component of reflex cutaneous vasodilatation with passive heat stress. We tested the hypothesis that nNOS inhibition would attenuate reflex cutaneous vasodilatation during sustained dynamic exercise in young healthy humans. All subjects first performed an incremental V?O2, peak test to exhaustion on a custom-built supine cycle ergometer. On a separate day, subjects were instrumented with four intradermal microdialysis fibres on the forearm and each randomly assigned as: (1) lactated Ringer's (control); (2) 20 mm N?-nitro-l-arginine methyl ester hydrochloride (non-selective NOS inhibitor); (3) 5 mm N-propyl-l-arginine (nNOS inhibitor); and (4) 10 mm N(5)-(1-iminoethyl)-l-ornithine dihydrochloride [endothelial NOS (eNOS) inhibitor]. Following microdialysis placement, subjects performed supine cycling with the experimental arm at heart level at 60% V?O2, peak for a period sufficient to raise core temperature 0.8°C. At the end of cycling, all microdialysis sites were locally heated to 43°C and sodium nitroprusside was perfused to elicit maximal vasodilatation. Mean arterial pressure, skin blood flow via laser-Doppler flowmetry and core temperature via ingestible telemetric pill were measured continuously; cutaneous vascular conductance (CVC) was calculated as laser-Doppler flowmetry/mean arterial pressure and normalized to maximum. There was no significant difference between control (58 ± 2%CVCmax) and nNOS-inhibited (56 ± 3%CVCmax) sites in response to exercise-induced hyperthermia. The increase in CVC at eNOS-inhibited (41 ± 3%CVCmax) and non-selective NOS-inhibited (40 ± 4%CVCmax) sites were significantly attenuated compared to control and nNOS-inhibited (P < 0.001 all conditions) but there was no difference between eNOS-inhibited and non-selective NOS-inhibited sites. These data suggest eNOS, not nNOS, mediate NO synthesis during reflex cutaneous vasodilatation with sustained dynamic exercise. PMID:25260636

  4. Saccadic compensation for reflexive optokinetic nystagmus just as good as compensation for volitional pursuit

    PubMed Central

    Harrison, James J.; Freeman, Tom C. A.; Sumner, Petroc

    2015-01-01

    The natural viewing behavior of moving observers ideally requires target-selecting saccades to be coordinated with automatic gaze-stabilizing eye movements such as optokinetic nystagmus. However, it is unknown whether saccade plans can compensate for reflexive movement of the eye during the variable saccade latency period, and it is unclear whether reflexive nystagmus is even accompanied by extraretinal signals carrying the eye movement information that could potentially underpin such compensation. We show that saccades do partially compensate for optokinetic nystagmus that displaces the eye during the saccade latency period. Moreover, this compensation is as good as for displacements due to voluntary smooth pursuit. In other words, the saccade system appears to be as well coordinated with reflexive nystagmus as it is with volitional pursuit, which in turn implies that extraretinal signals accompany nystagmus and are just as informative as those accompanying pursuit. PMID:25624463

  5. Age-related changes in human vestibulo-ocular and optokinetic reflexes: Pseudorandom rotation tests

    NASA Technical Reports Server (NTRS)

    Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

    1989-01-01

    The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters which describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year.

  6. Cortical stimulation causes long-term changes in H-reflexes and spinal motoneuron GABA receptors

    PubMed Central

    Wang, Yu; Chen, Yi; Chen, Lu; Wolpaw, Jonathan R.

    2012-01-01

    The cortex gradually modifies the spinal cord during development, throughout later life, and in response to trauma or disease. The mechanisms of this essential function are not well understood. In this study, weak electrical stimulation of rat sensorimotor cortex increased the soleus H-reflex, increased the numbers and sizes of GABAergic spinal interneurons and GABAergic terminals on soleus motoneurons, and decreased GABAA and GABAB receptor labeling in these motoneurons. Several months after the stimulation ended the interneuron and terminal increases had disappeared, but the H-reflex increase and the receptor decreases remained. The changes in GABAergic terminals and GABAB receptors accurately predicted the changes in H-reflex size. The results reveal a new long-term dimension to cortical-spinal interactions and raise new therapeutic possibilities. PMID:22933718

  7. Spinal reflex evoked by a pair of opposing pulsed magnetic fields

    NASA Astrophysics Data System (ADS)

    Ueno, S.; Hiwaki, O.

    1991-04-01

    A noninvasive method of magnetic stimulation of the spinal roots was designed. The basic idea is to concentrate induced eddy currents in a target by a pair of opposing pulsed magnetic fields. A figure-eight coil was positioned outside the median of the back so that time varying magnetic fields pass through the body in opposite directions around the target. Magnetic stimulation of the spinal roots of human and a rabbit was carried out. It was found that each spine level can be stimulated selectively, producing electromyographic waves related to both the H-reflex and M-wave. The results indicate that the M-wave can be produced by currents flowing either in the rostral or caudal direction, whereas the H-reflex is only generated by currents flowing in the caudal direction. The H-reflex elicited by magnetic stimulation of nerves in the vicinity of the spine becomes a new tool in diagnosis of neuromuscular system diseases.

  8. Modulation of eyeblink and postauricular reflexes during the anticipation and viewing of food images.

    PubMed

    Hebert, Karen R; Valle-Inclán, Fernando; Hackley, Steven A

    2015-04-01

    One of the goals of neuroscience research on the reward system is to fractionate its functions into meaningful subcomponents. To this end, the present study examined emotional modulation of the eyeblink and postauricular components of startle in 60 young adults during anticipation and viewing of food images. Appetitive and disgusting photos served as rewards and punishments in a guessing game. Reflexes evoked during anticipation were not influenced by valence, consistent with the prevailing view that startle modulation indexes hedonic impact (liking) rather than incentive salience (wanting). During the slide-viewing period, postauricular reflexes were larger for correct than incorrect feedback, whereas the reverse was true for blink reflexes. Probes were delivered in brief trains, but only the first response exhibited this pattern. The specificity of affective startle modification makes it a valuable tool for studying the reward system. PMID:25336280

  9. Device for rapid quantification of human carotid baroreceptor-cardiac reflex responses

    NASA Technical Reports Server (NTRS)

    Sprenkle, J. M.; Eckberg, D. L.; Goble, R. L.; Schelhorn, J. J.; Halliday, H. C.

    1986-01-01

    A new device has been designed, constructed, and evaluated to characterize the human carotid baroreceptor-cardiac reflex response relation rapidly. This system was designed for study of reflex responses of astronauts before, during, and after space travel. The system comprises a new tightly sealing silicon rubber neck chamber, a stepping motor-driven electrodeposited nickel bellows pressure system, capable of delivering sequential R-wave-triggered neck chamber pressure changes between +40 and -65 mmHg, and a microprocessor-based electronics system for control of pressure steps and analysis and display of responses. This new system provokes classic sigmoid baroreceptor-cardiac reflex responses with threshold, linear, and saturation ranges in most human volunteers during one held expiration.

  10. Nitric Oxide/cGMP-Mediated Protein Kinase A Activation in the Antennal Lobes Plays an Important Role in Appetitive Reflex

    E-print Network

    Menzel, Randolf - Institut für Biologie

    Role in Appetitive Reflex Habituation in the Honeybee Uli Mu¨ ller1 and Herbert Hildebrandt2 1Institut of a reflex pathway (Thompson and Spencer, 1966; Groves and Thompson, 1970). Paradoxically, com- pared

  11. Ontogeny of Mouse Vestibulo-Ocular Reflex Following Genetic or Environmental Alteration of Gravity Sensing

    PubMed Central

    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. PMID:22808156

  12. Bulbocavernosus muscle responses after suprapubic stimulation: analysis and measurement of suprapubic bulbocavernosus reflex latency.

    PubMed

    Amarenco, Gerard; Bayle, Beatrice; Ismael, Samer Sheikh; Kerdraon, Jacques

    2002-01-01

    Our objective was to describe pelvic floor responses with measurement of reflex latency after suprapubic mechanical stimulation. Twenty-one patients without neurological disease were studied. They were 14 women and seven men. The mean age was 51 (SD = 14.2). Motor responses were recorded with a needle electrode inserted in the left bulbocavernosus muscle. Stimulation was delivered with an electromechanical hammer, tapping directly on the suprapubic area. A polyphasic muscular response was always easily elicited in all patients. The man latency was 67.5 milliseconds (SD = 14.7). The reproducibility between the first and second mechanical responses was good with no statistical difference (r=0.966;P = 0.0001). In three patients who underwent cystometry, no rise in detrusor pressure was observed during mechanical stimulation of the suprapubic area. Our study clearly demonstrates a suprapubic bulbocavernosus reflex (SBR). Tapping the suprapubic area is a strong stimulus, reflexively mediated, used in the management of neurogenic bladder to determine a bladder contraction. However, the reflex consisting of pelvic floor muscle contraction after suprapubic stimulation was not specifically studied in humans. Many arguments can be put forth for a polysynaptic reflex (polyphasic response, habituation and short latency of the reflex, mean latency in the habitual values of R2 responses after electrical stimulation of the dorsal nerve of the penis). We hypothesize that the true stimulus is the stimulation of the bladder wall tensoreceptors, the integration level of the SBR is the sacral segments and the efferent limb the pudendal nerve, and afferent pathways could be conducted by pelvic nerve fibers. Competition between a preponderant (or exaggerated) SBR and a bladder contraction after suprapubic tapping may constitute an equivalent of detrusor-sphincter dyssynergia in some suprasacral bladders. PMID:11948714

  13. Interactions Between Limb and Environmental Mechanics Influence Stretch Reflex Sensitivity in the Human Arm

    PubMed Central

    Krutky, Matthew A.; Ravichandran, Vengateswaran J.; Trumbower, Randy D.

    2010-01-01

    Stretch reflexes contribute to arm impedance and longer-latency stretch reflexes exhibit increased sensitivity during interactions with compliant or unstable environments. This increased sensitivity is consistent with a regulation of arm impedance to compensate for decreased stability of the environment, but the specificity of this modulation has yet to be investigated. Many tasks, such as tool use, compromise arm stability along specific directions, and stretch reflexes tuned to those directions could present an efficient mechanism for regulating arm impedance in a task-appropriate manner. To be effective, such tuning should adapt not only to the mechanical properties of the environment but to those properties in relation to the arm, which also has directionally specific mechanical properties. The purpose of this study was to investigate the specificity of stretch reflex modulation during interactions with mechanical environments that challenge arm stability. The tested environments were unstable, having the characteristics of a negative stiffness spring. These were either aligned or orthogonal to the direction of maximal endpoint stiffness for each subject. Our results demonstrate preferential increases in reflexes, elicited within 50–100 ms of perturbation onset, to perturbations applied specifically along the direction of the destabilizing environments. This increase occurred only when the magnitude of the environmental instability exceeded endpoint stiffness along the same direction. These results are consistent with task-specific reflex modulation tuned to the mechanical properties of the environment relative to those of the human arm. They demonstrate a highly adaptable, involuntary mechanism that may be used to modulate limb impedance along specific directions. PMID:19906880

  14. Renal denervation normalizes pressure and baroreceptor reflex in high renin hypertension in conscious rats.

    PubMed

    Oliveira, V L; Irigoyen, M C; Moreira, E D; Strunz, C; Krieger, E M

    1992-02-01

    High renin hypertension is usually accompanied by impairment of the baroreceptor reflexes. This feature has been mostly ascribed to overactivity of the renin-angiotensin system. However, renal nerves could also modulate the baroreceptor reflexes. In the present experiments, the effect of renal denervation on the depressed baroreceptor reflexes was studied in rats subjected to aortic ligation between the renal arteries. Renal denervation of the ischemic kidney was performed at the same time as aortic ligation. The resulting effects on arterial pressure, heart rate, plasma renin activity, and baroreceptor reflex control of heart rate were studied 10-12 days after ligation and denervation. Aortic ligation induced high levels of mean arterial pressure (166 +/- 6 versus 110 +/- 3 mm Hg in controls), heart rate (380 +/- 9 versus 352 +/- 8 beats per minute in controls), and plasma renin activity (44 +/- 5 versus 6 +/- 1.2 ng angiotensin I/ml/hr). The baroreceptor reflex sensitivity for bradycardia and tachycardia was significantly reduced (-0.18 +/- 0.04 and -0.18 +/- 0.05, respectively, versus -2.3 +/- 0.01 and -2.4 +2- 0.1 beats per minute per mm Hg in controls). Denervation of the ischemic kidney attenuated the development of hypertension in aortic-ligated rats (122 +/- 3 mm Hg), lowering heart rate (319 +/- 8 beats per minute) and normalizing baroreceptor reflex sensitivity to bradycardia (-2.0 +/- 0.2 beats per minute per mm Hg) and to tachycardia (-4.0 +/- 0.1 beats per minute per mm Hg). Plasma renin activity was also normalized (4.3 +/- 2.4 ng angiotensin I/ml/hr).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1735574

  15. A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Brandt, T.

    1993-01-01

    Conventional views of the vestibulo-ocular reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved--locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (< 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  16. Attempted bladder reinnervation and creation of a scratch reflex for bladder emptying through a somatic-to-autonomic intradural anastomosis.

    PubMed

    Tuite, Gerald F; Storrs, Bruce B; Homsy, Yves L; Gaskill, Sarah J; Polsky, Ethan G; Reilly, Margaret A; Gonzalez-Gomez, Ignacio; Winesett, S Parrish; Rodriguez, Luis F; Carey, Carolyn M; Perlman, Sharon A; Tetreault, Lisa

    2013-07-01

    An intradural somatic-to-autonomic anastomosis, or Xiao procedure, has been described to create a "skin-CNS-bladder" reflex that improves bladder and bowel function in patients with neurogenic bladder and bowel dysfunction. The authors present their experience with a 10-year-old boy with chronic neurogenic bladder and bowel dysfunction related to spinal cord injury who underwent the Xiao procedure. After undergoing a left L-5 ventral root to left S2-3 intradural anastomosis, the patient reported that his bladder and bowel dysfunction improved between 6 and 12 months. Two years after the procedure, however, he reported that there was no change in his bladder or bowel dysfunction as compared with his condition prior to the procedure. Frequent, systematic multidisciplinary evaluations produced conflicting data. Electrophysiological and histological evaluation of the previously performed anastomosis during surgical reexploration 3 years after the Xiao procedure revealed that the anastomosis was in anatomical continuity but neuroma formation had prevented reinnervation. Nerve action potentials were not demonstrable across the anastomosis, and stimulation of the nerve above and below the anastomosis created no bladder or perineal contractions. This is the first clinical report on the outcome of the Xiao procedure in a child with spinal cord injury outside of China. It is impossible to draw broad conclusions about the efficacy of the procedure based on a single patient with no demonstrable benefit. However, future studies should carefully interpret transient improvements in bladder function, urodynamic findings, and the patient's ability to void in response to scratching after the Xiao procedure. The authors' experience with the featured patient, in whom reinnervation could not be demonstrated, suggests that such changes could be related to factors other than the establishment of a skin-CNS-bladder reflex as a result of a somatic-to-autonomic anastomosis. PMID:23662931

  17. Abstract We examined the amplitude modulation of the soleus (Sol) H-reflex during controlled variations of the

    E-print Network

    -reflex excitability of distant limb muscles such as the soleus (Chapman et al. 1991). Collectively, there is conAbstract We examined the amplitude modulation of the soleus (Sol) H-reflex during controlled of muscle afferents from the medial gastrocnemius (MG) nerve. We found that with subjects in the supine

  18. Distributed and Partially Separate Pools of Neurons Are Correlated with Two Different Components of the Gill-Withdrawal Reflex in

    E-print Network

    Kleinfeld, David

    of the Gill-Withdrawal Reflex in Aplysia Michal Zochowski,1,2,5 Lawrence B. Cohen,1,2 Galit Fuhrmann,2 abdominal ganglion with the movement of the gill during the gill-withdrawal reflex. We discriminated four-order sensory neurons that respond to the onset and offset of stimulation of the gill and are active before

  19. Trigeminocardiac reflex in a child during pre-Onyx DMSO injection for juvenile nasopharyngeal angiofibroma embolization. A case report.

    PubMed

    Puri, A S; Thiex, R; Zarzour, H; Rahbar, R; Orbach, D B

    2011-03-01

    We describe the occurrence of the trigeminocardiac reflex (TCR) during DMSO pre-flushing of the microcatheter in preparation for Onyx embolization via the internal maxillary artery. TCR has not been previously associated with embolization of extradural entities. Familiarity with this clinical reflex and its proper management may help in planning neurointerventional procedures involving DMSO injection in the trigeminal territory. PMID:21561553

  20. Navigating the Tides of Change: Revisiting the Notion of Reflexivity in the Context of Social Learning for Transboundary Collective Experimentation

    ERIC Educational Resources Information Center

    Bastrup-Birk, Henriette; Wildemeersch, Danny

    2011-01-01

    Social learning theory in the context of multi-actor engagement tends to relate reflexivity primarily to critical questioning of theories-in-use. We argue that viewing suspensive dialogue and imaginative envisioning as additional stages of reflexivity will serve at least three purposes: prevent over-emphasis on instrumental rationality focusing on…

  1. More than meets the eye: the use of videonarratives to facilitate doctoral students’ reflexivity on their doctoral journeys

    Microsoft Academic Search

    Carol A. Taylor

    2011-01-01

    This article discusses findings from a UK Higher Education Academy project, which used digital video to promote doctoral students’ reflexivity. The project aimed to facilitate doctoral students’ research skills through the making of videonarratives; create spaces for reflexivity on the relations between research, narrative and identity; and consider the opportunities and problems offered by the use of digital video as

  2. Frontal lobe lesions in man cause difficulties in suppressing reflexive glances and in generating goal-directed saccades

    Microsoft Academic Search

    D. Guitton; H. A. Buchtel; R. M. Douglas

    1985-01-01

    Summary  The frontal eye field (FEF) and superior colliculus (SC) are thought to form two parallel systems for generating saccadic eye movements. The SC is thought classically to mediate reflex-like orienting movements. Thus it can be hypothesized that the FEF exerts a higher level control on a visual grasp reflex. To test this hypothesis we have studied the saccades of patients

  3. ‘I did it my way’: voice, visuality and identity in doctoral students' reflexive videonarratives on their doctoral research journeys

    Microsoft Academic Search

    Carol A. Taylor; Yvonne Downs; Rob Baker; Gladson Chikwa

    2011-01-01

    This article presents accounts of four UK doctoral students' engagement in a Higher Education Academy project which used digital video (DV) to promote reflexivity on their doctoral journeys. Proceeding from participants' accounts of the production of their videonarratives, the article analyses the relations between doctoral research, reflexivity and the use of DV, and their articulation in different ways by the

  4. THE EXOSKELETON AND INSECT PROPRIOCEPTION II. REFLEX EFFECTS OF TIBIAL CAMPANIFORM SENSILLA IN THE AMERICAN COCKROACH, PERIPLANETA AMERICANA

    Microsoft Academic Search

    SASHA N. ZILL; DAVID T. MORAN; FRANCISCO G. VARELA

    SUMMARY 1. Mechanical stimulation of individual tibia! campaniform sensilla produces specific reflex effects upon motoneurones to leg muscles. 2. The reflex effects of a campaniform sensillum depend upon the orientation of its cuticular cap. The proximal sensilla, oriented perpendicular to the long axis of the tibia, excite slow motoneurones to the extensor tibiae and extensor trochanteris muscles and inhibit slow

  5. Effect of stimulus size and luminance on the rod-, cone-, and melanopsin-mediated pupillary light reflex

    PubMed Central

    Park, Jason C.; McAnany, J. Jason

    2015-01-01

    This study determined if the pupillary light reflex (PLR) driven by brief stimulus presentations can be accounted for by the product of stimulus luminance and area (i.e., corneal flux density, CFD) under conditions biased toward the rod, cone, and melanopsin pathways. Five visually normal subjects participated in the study. Stimuli consisted of 1-s short- and long-wavelength flashes that spanned a large range of luminance and angular subtense. The stimuli were presented in the central visual field in the dark (rod and melanopsin conditions) and against a rod-suppressing short-wavelength background (cone condition). Rod- and cone-mediated PLRs were measured at the maximum constriction after stimulus onset whereas the melanopsin-mediated PLR was measured 5–7 s after stimulus offset. The rod- and melanopsin-mediated PLRs were well accounted for by CFD, such that doubling the stimulus luminance had the same effect on the PLR as doubling the stimulus area. Melanopsin-mediated PLRs were elicited only by short-wavelength, large (>16°) stimuli with luminance greater than 10 cd/m2, but when present, the melanopsin-mediated PLR was well accounted for by CFD. In contrast, CFD could not account for the cone-mediated PLR because the PLR was approximately independent of stimulus size but strongly dependent on stimulus luminance. These findings highlight important differences in how stimulus luminance and size combine to govern the PLR elicited by brief flashes under rod-, cone-, and melanopsin-mediated conditions. PMID:25788707

  6. Visual suppression of the vestibulo-ocular reflex during space flight

    NASA Technical Reports Server (NTRS)

    Uri, John J.; Thornton, William E.; Moore, Thomas P.; Pool, Sam L.

    1989-01-01

    Visual suppression of the vestibulo-ocular reflex was studied in 16 subjects on 4 Space Shuttle missions. Eye movements were recorded by electro-oculography while subjects fixated a head mounted target during active sinusoidal head oscillation at 0.3 Hz. Adequacy of suppression was evaluated by the number of nystagmus beats, the mean amplitude of each beat, and the cumulative amplitude of nystagmus during two head oscillation cycles. Vestibulo-ocular reflex suppression was unaffected by space flight. Subjects with space motion sickness during flight had significantly more nystagmus beats than unaffected individuals. These susceptible subjects also tended to have more nystagmus beats before flight.

  7. The vagus nerve and the inflammatory reflex—linking immunity and metabolism

    PubMed Central

    Pavlov, Valentin A.; Tracey, Kevin J.

    2014-01-01

    The vagus nerve has an important role in regulation of metabolic homeostasis, and efferent vagus nerve-mediated cholinergic signalling controls immune function and proinflammatory responses via the inflammatory reflex. Dysregulation of metabolism and immune function in obesity are associated with chronic inflammation, a critical step in the pathogenesis of insulin resistance and type 2 diabetes mellitus. Cholinergic mechanisms within the inflammatory reflex have, in the past 2 years, been implicated in attenuating obesity-related inflammation and metabolic complications. This knowledge has led to the exploration of novel therapeutic approaches in the treatment of obesity-related disorders. PMID:23169440

  8. Possible role of repetitive practice of activities requiring reflexive responses in the treatment of Tourette's disorder.

    PubMed

    Wang, Huei-Shyong; Kuo, Meng-Fai; Stern, Jeremy S

    2011-01-01

    We report 2 boys, 11 and 7 years old, whose Tourette's disorder improved significantly after a period of repeated, sustained practice of activities requiring reflexive responses One boy engaged in physical exercise including hand-eye co-ordination (table tennis for 6 hours every weekday) and the other learned foreign languages (5 languages within 3 years). Tics may be thought of as a kind of overflow of energy, and excessive energy consumption with physical or mental exercise may improve the motor disorder and associated comorbidities. However, the exercise may require a quick, reflexive response to visual or verbal stimuli. PMID:22196069

  9. Ionotropic glutamate receptors in the external lateral parabrachial nucleus participate in processing cardiac sympathoexcitatory reflexes

    PubMed Central

    Guo, Zhi-Ling; Longhurst, John C.

    2012-01-01

    Stimulation of cardiac sympathetic afferents during myocardial ischemia with metabolites such as bradykinin (BK) evokes sympathoexcitatory reflex responses and activates neurons in the external lateral parabrachial nucleus (elPBN). The present study tested the hypothesis that this region in the pons processes sympathoexcitatory cardiac reflexes through an ionotropic glutamate receptor mechanism. The ischemic metabolite BK (0.1–1 ?g) was injected into the pericardial space of anesthetized and bilaterally vagotomized or intact cats. Hemodynamic and renal sympathetic nerve activity (RSNA) responses to repeated administration of BK before and after unilateral 50-nl microinjections of kynurenic acid (Kyn; 25 mM), 2-amino-5-phosphonopentanoic acid (AP5; 25 mM), and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzol(F)quinoxaline (NBQX; 10 mM) into the elPBN were recorded. Intrapericardial BK evoked significant increases in mean arterial pressure (MAP) and RSNA in seven vagotomized cats. After blockade of glutamate receptors with the nonselective glutamate receptor antagonist Kyn, the BK-evoked reflex increases in MAP (50 ± 6 vs. 29 ± 2 mmHg) and RSNA (59 ± 8.6 vs. 29 ± 4.7%, before vs. after) were significantly attenuated. The BK-evoked responses returned to pre-Kyn levels 85 min after the application of Kyn. Similarly, BK-evoked reflex responses were reversibly attenuated by blockade of glutamate N-methyl-d-aspartate (NMDA) receptors with AP5 (n = 5) and ?-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors with NBQX (n = 5). In contrast, we observed that the repetitive administration of BK evoked consistent reflex responses including MAP and RSNA before and after microinjection of 50 nl of the artificial cerebrospinal fluid vehicle into the elPBN in five animals. Microinjection of glutamate receptor antagonists into regions outside the elPBN did not alter BK-induced reflex responses. Microinjection of Kyn into the elPBN reversibly attenuated BK-induced reflex responses in four vagus intact animals. These data are the first to show that NMDA and AMPA ionotropic glutamate receptors in the elPBN play an important role in processing cardiac excitatory reflex responses. PMID:22268111

  10. Iron Deficiency with or without Anemia Impairs Prepulse Inhibition of the Startle Reflex

    PubMed Central

    Pisansky, Marc T.; Wickham, Robert J.; Su, Jianjun; Fretham, Stephanie; Yuan, Li-Lian; Sun, Mu; Gewirtz, Jonathan C.; Georgieff, Michael K.

    2013-01-01

    Iron deficiency (ID) during early life causes long-lasting detrimental cognitive sequelae, many of which are linked to alterations in hippocampus function, dopamine synthesis, and the modulation of dopaminergic circuitry by the hippocampus. These same features have been implicated in the origins of schizophrenia, a neuropsychiatric disorder with significant cognitive impairments. Deficits in sensorimotor gating represent a reliable endophenotype of schizophrenia that can be measured by prepulse inhibition (PPI) of the acoustic startle reflex. Using two rodent model systems, we investigated the influence of early-life ID on PPI in adulthood. To isolate the role of hippocampal iron in PPI, our mouse model utilized a timed (embryonic day 18.5), hippocampus-specific knockout of Slc11a2, a gene coding an important regulator of cellular iron uptake, the divalent metal transport type 1 protein (DMT-1). Our second model used a classic rat dietary-based global ID during gestation, a condition that closely mimics human gestational ID anemia (IDA). Both models exhibited impaired PPI in adulthood. Furthermore, our DMT-1 knockout model displayed reduced long-term potentiation (LTP) and elevated paired pulse facilitation (PPF), electrophysiological results consistent with previous findings in the IDA rat model. These results, in combination with previous findings demonstrating impaired hippocampus functioning and altered dopaminergic and glutamatergic neurotransmission, suggest that iron availability within the hippocampus is critical for the neurodevelopmental processes underlying sensorimotor gating. Ultimately, evidence of reduced PPI in both of our models may offer insights into the roles of fetal ID and the hippocampus in the pathophysiology of schizophrenia. PMID:23733517

  11. Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Trillenberg, P.; Shelhamer, M.; Roberts, D. C.; Zee, D. S.

    2003-01-01

    The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head movements.

  12. Reflections from a Tarnished Mirror: An Application of Alvesson and Sköldberg's "Reflexive Interpretation" to a Study of Curriculum Design in Higher Education

    ERIC Educational Resources Information Center

    Bates, Agnieszka

    2014-01-01

    It is now widely understood that reflexivity constitutes a vital element of good qualitative research. However, reflexive accounts often draw on a single theoretical framework, thus privileging and legitimizing a particular interpretation of empirical data. This paper focuses on Alvesson and Sköldberg's "reflexive interpretation",…

  13. Investigating Hemispheric Lateralization of Reflexive Attention to Gaze and Arrow Cues

    ERIC Educational Resources Information Center

    Marotta, Andrea; Lupianez, Juan; Casagrande, Maria

    2012-01-01

    Recent studies have demonstrated that central cues, such as eyes and arrows, reflexively trigger attentional shifts. However, it is not clear whether the attentional mechanisms induced by these two cues are similar or rather differ in some important way. We investigated hemispheric lateralization of the orienting effects induced by the two cue…

  14. Interaction between vestibulosympathetic and skeletal muscle reflexes on sympathetic activity in humans

    NASA Technical Reports Server (NTRS)

    Ray, C. A.

    2001-01-01

    Evidence from animals indicates that skeletal muscle afferents activate the vestibular nuclei and that both vestibular and skeletal muscle afferents have inputs to the ventrolateral medulla. The purpose of the present study was to investigate the interaction between the vestibulosympathetic and skeletal muscle reflexes on muscle sympathetic nerve activity (MSNA) and arterial pressure in humans. MSNA, arterial pressure, and heart rate were measured in 17 healthy subjects in the prone position during three experimental trials. The three trials were 2 min of 1) head-down rotation (HDR) to engage the vestibulosympathetic reflex, 2) isometric handgrip (IHG) at 30% maximal voluntary contraction to activate skeletal muscle afferents, and 3) HDR and IHG performed simultaneously. The order of the three trials was randomized. HDR and IHG performed alone increased total MSNA by 46 +/- 16 and 77 +/- 24 units, respectively (P < 0.01). During the HDR plus IHG trial, MSNA increased 142 +/- 38 units (P < 0.01). This increase was not significantly different from the sum of the individual trials (130 +/- 41 units). This finding was also observed with mean arterial pressure (sum = 21 +/- 2 mmHg and HDR + IHG = 22 +/- 2 mmHg). These findings suggest that there is an additive interaction for MSNA and arterial pressure when the vestibulosympathetic and skeletal muscle reflexes are engaged simultaneously in humans. Therefore, no central modulation exists between these two reflexes with regard to MSNA output in humans.

  15. Fast food\\/organic food: Reflexive tastes and the making of 'yuppie chow'

    Microsoft Academic Search

    Julie Guthman

    2003-01-01

    Organic food consumption is one of several new trends in eating read as active opposition to industrialized food provision. While fast food consumption is characterized by compulsive gluttony, manifest in fat bodies, alternative consumption practices are seen to be driven by conscious reflexivity, such that consumers monitor, reflect upon and adapt their personal conduct in light of its perceived consequences.

  16. Cardiac nociceptive reflexes after transmyocardial laser revascularization: Implications for the neural hypothesis of angina relief

    Microsoft Academic Search

    Anthony J. Minisi; On Topaz; M. Susan Quinn; Laxmi B. Mohanty

    2001-01-01

    Objective: The mechanism by which transmyocardial laser revascularization relieves angina is not understood. One theory is that laser-induced thermal damage to cardiac nerves results in cardiac denervation. This study examined the acute effects of transmyocardial laser revascularization on reflex responses mediated by cardiac nociceptors, the left ventricular receptors with sympathetic afferent fibers that are thought to mediate anginal chest pain.

  17. Spastic Long-Lasting Reflexes in the Awake Rat After Sacral Spinal Cord Injury

    E-print Network

    Gorassini, Monica

    Spastic Long-Lasting Reflexes in the Awake Rat After Sacral Spinal Cord Injury D. J. Bennett, L in the awake rat after sacral spinal cord injury. J Neurophysiol 91: 2247­2258, 2004; 10.1152/jn.00946 The debilitating spasms that accompany spinal cord injury develop slowly are often not fully manifested for months

  18. Modification of experimental UV erythema by external steroids-a reflex photometric study

    Microsoft Academic Search

    P. Altmeyer; F. Noedl

    1977-01-01

    A method for reflex photometric detection of the modification of a model of inflammation (UV erythema) by external corticoids is presented. The steroids which most effectively suppress erythema formation are those which have the strongest vasoconstrictor potency also on unchanged skin. A tachyphylaxis phenomenon can also be demonstrated after several applications of a synthetic steroid to the inflammation model.

  19. Reflex: Managing Sensor Data Processing in Mobile Systems Technical Report 03-15-2010

    E-print Network

    Zhong, Lin

    -area networking technologies such as Bluetooth provide even more wireless sensors. These sensors can supply rich1 Reflex: Managing Sensor Data Processing in Mobile Systems Technical Report 03-15-2010 Xiaozhu Lin Engineering Rice University, Houston, TX 77005 Abstract Many emerging mobile services leverage sensors

  20. Mammalian Diving Reflex 2010 1 Minority Science Programs School of Biological Sciences University of California, Irvine

    E-print Network

    Rose, Michael R.

    . Why is oxygen so important to your body? Mitochondria in your cells use oxygen to help make the energy that maintains your metabolism and keeps you alive. 4. Does your body increase or decrease its metabolic demand (conserve oxygen in the lungs) #12;Mammalian Diving Reflex 2010 2 Minority Science Programs ­ School

  1. The Effect of Postsurgical Edema of the Knee Joint on Reflex Inhibition of the Quadriceps Femoris

    E-print Network

    McDonough, Andrew L.; Weir, Joseph P.

    1996-01-01

    The purpose of this case study was to investigate reflex inhibition of the quadriceps femoris in a subject with postsurgical edema of the left knee. The subject was a 45-year-old male with a traumatic knee injury with resultant edema who underwent...

  2. Bourdieu Knew More than How to Play Tennis! An Empirically Based Discussion of Habituation and Reflexivity

    ERIC Educational Resources Information Center

    Strandbu, Åse; Steen-Johnsen, Kari

    2014-01-01

    This paper explores the role of reflexivity in habituation by contrasting the learning of aerobics and basketball with the acquisition of gendered bodily skills. The discussion is inspired by the paper "So, how did Bourdieu learn to play tennis? Habitus, consciousness and habituation," by Noble and Watkins (2003), which represents a…

  3. Autonomic dysfunction in muscular dystrophy: a theoretical framework for muscle reflex involvement

    PubMed Central

    Smith, Scott A.; Downey, Ryan M.; Williamson, Jon W.; Mizuno, Masaki

    2014-01-01

    Muscular dystrophies are a heterogeneous group of genetically inherited disorders whose most prominent clinical feature is progressive degeneration of skeletal muscle. In several forms of the disease, the function of cardiac muscle is likewise affected. The primary defect in this group of diseases is caused by mutations in myocyte proteins important to cellular structure and/or performance. That being stated, a growing body of evidence suggests that the development of autonomic dysfunction may secondarily contribute to the generation of skeletal and cardio-myopathy in muscular dystrophy. Indeed, abnormalities in the regulation of both sympathetic and parasympathetic nerve activity have been reported in a number of muscular dystrophy variants. However, the mechanisms mediating this autonomic dysfunction remain relatively unknown. An autonomic reflex originating in skeletal muscle, the exercise pressor reflex, is known to contribute significantly to the control of sympathetic and parasympathetic activity when stimulated. Given the skeletal myopathy that develops with muscular dystrophy, it is logical to suggest that the function of this reflex might also be abnormal with the pathogenesis of disease. As such, it may contribute to or exacerbate the autonomic dysfunction that manifests. This possibility along with a basic description of exercise pressor reflex function in health and disease are reviewed. A better understanding of the mechanisms that possibly underlie autonomic dysfunction in muscular dystrophy may not only facilitate further research but could also lead to the identification of new therapeutic targets for the treatment of muscular dystrophy. PMID:24600397

  4. A Positive Babinski Reflex Predicts Delayed Neuropsychiatric Sequelae in Chinese Patients with Carbon Monoxide Poisoning

    PubMed Central

    Zou, Jian-Fang; Guo, Qiming; Shao, Hua; Li, Bin; Du, Yuxiu; Liu, Maofeng; Liu, Fengling; Dai, Lixin; Chung, Min-Hsien; Lin, Hung-Jung; Guo, How-Ran; Yang, Tzu-Meng; Huang, Chien-Cheng; Hsu, Chien-Chin

    2014-01-01

    As the human population increased in China, the carbon monoxide is a serious environmental toxin in public health. However, predicting the delayed neuropsychiatric sequelae (DNS) of carbon monoxide poisoning (COP) has not been well studied. We investigated the independent predictors of DNS in patients with COP. This study was conducted at four hospitals in China. Data were retrospectively collected from 258 patients with COP between November 1990 and October 2011. DNS was the primary endpoint. A positive Babinski reflex was the independent predictor for DNS: sensitivity = 53.8% (95% confidence interval [CI]: 26.1–79.6), specificity = 88.6% (95% CI: 83.7–92.1), positive predictive value (PPV) = 20.0% (95% CI: 9.1–37.5), and negative predictive value (NPV) = 97.3% (95% CI: 94.0–98.9). The area under the receiver operating characteristic curve = 0.712 (95% CI: 0.544–0.880). A positive Babinski reflex was very memorable, immediately available, and applicable in clinical practice. Even when the sensitivity and PPV of a positive Babinski reflex were unsatisfactory, it had a good specificity and NPV for excluding the risk of DNS. In patients without a positive Babinski reflex, the risk for DNS was only 2.7%. This finding may help physicians make decisions about dispositions for patients with COP. PMID:24959589

  5. Together, alone? Reflexive leadership and political activism in membership-based social movement organizations

    Microsoft Academic Search

    Alexander Hensby; Joanne Sibthorpe; Stephen Driver

    2009-01-01

    Abstract Within the contemporary context of networked political activism, a global civil society and individualized forms of public participation, this paper assesses the challenges these pose to established membership-basedsoci al movement organizations. Much of the existing literature focuses on the transition from traditional hierarchical structures towards fluid networks of political activism This paper offers a more reflexive approach in considering

  6. The afferent and efferent pathways of the recto-colonic reflex in the dog.

    PubMed

    Fukuda, H; Fukai, K

    1985-01-01

    The nature of the afferent and efferent pathways of the recto-colonic reflex was studied electrophysiologically in the dog. A compound action potential consisting of many peaks was evoked on a sacral dorsal rootlet by a stimulus to the ipsilateral rectal strands of the pelvic nerve. Conduction velocities of the peaks indicate that A delta and C afferent fibers innervate the colon and rectum. When the stimuli were subthreshold for C fibers, the reflex discharges of contralateral parasympathetic post-ganglionic fibers in the rectal strands and the reflex contraction of the colon were smaller than those caused by stronger stimuli. As the intensity of the stimulus to the sacral ventral roots was weakened, response peaks of preganglionic B fibers in the rectal branch, post-ganglionic C fibers in the rectal strands and a bladder branch of the pelvic nerve disappeared in the order of slow to fast conduction velocities. Contraction of the colon also decreased. The number of peaks arising from each nerve correlated well with the strength of the contraction. These results indicate that the peripheral limbs of the recto-colonic reflex arc consist of afferent A delta and C fibers, preganglionic B fibers and post-ganglionic C fibers. PMID:4079135

  7. Components of the neural circuitry of the vaginocavernosus reflex in rabbits.

    PubMed

    Cruz, Yolanda; Rodríguez-Antolín, Jorge; Nicolás, Leticia; Martínez-Gómez, Margarita; Lucio, Rosa Angélica

    2010-01-10

    In mammals the mechanisms underlying female sexual and reproductive biology are poorly understood. Little attention has been paid to striated muscles and their neural regulation. The aim of the present study was to describe the components of the vaginocavernosus reflex in adult rabbits. It was found that mechanical stimulation of the glans of the clitoris and the perineal vagina induced electromyographic (EMG) responses in bulbocavernosus (Bcm) and ischiocavernosus (Icm) muscles. Unilateral and bilateral nerve transection indicated that the clitoral nerve is the main afferent path of the reflex and that it recruits ipsilateral and contralateral perineal motoneurons. Injection of horseradish peroxides-wheat germ agglutinin (HRP-WGA) into the Bcm and Icm labeled spinal motoneurons scattered in L7 and S1 segments. According to the results of this study and previous work, the elements of the vaginocavernosus reflex may be described as follows. Mechanical receptors are located in the glans clitoris and in the wall of the perineal vagina. The main afferent pathway is the clitoral nerve. It activates ipsilateral and contralateral Bcm and Icm motoneurons in lumbosacral segments. Axons of efferent neurons travel through the clitoral and ischiocavernosus nerves, and the effectors are the Bcm and Icm perineal muscles. Identification of neural components of the vaginocavernosus reflex in rabbits will allow the use of this animal as a model to assess the physiological characteristics of the perineal motoneurons as well as the contribution of the Bcm and Icm in female urogenital functions. PMID:19937711

  8. Variable Foreperiod Deficits in Parkinson's Disease: Dissociation across Reflexive and Voluntary Behaviors

    ERIC Educational Resources Information Center

    Jurkowski, A.J.; Stepp, E.; Hackley, S.A.

    2005-01-01

    The effect of a visual warning signal (1.0-6.5s random foreperiod, FP) on the latency of voluntary (hand-grip) and reflexive (startle-eyeblink) reactions was investigated in Parkinson's disease (PD) patients and in young and aged control subjects. Equivalent FP effects on blink were observed across groups. By contrast, FP effects diverged for…

  9. EVALUATION OF SENSORY SYSTEM FUNCTION USING REFLEX MODIFICATION OF THE STARTLE RESPONSE

    EPA Science Inventory

    Methods to measure damage to sensory systems following toxicant exposure vary from rapid and subjective tests (e.g., pinna reflex) to time-consuming and objective tests (e.g., psychophysical tests). eflex modification of the startle response represents an alternative technique in...

  10. Habituation and adaptation of the vestibuloocular reflex: a model of differential control by the vestibulocerebellum

    Microsoft Academic Search

    Helen Cohen; Bernard Cohen; Theodore Raphan; Walter Waespe

    1992-01-01

    We habituated the dominant time constant of the horizontal vestibuloocular reflex (VOR) of rhesus and cynomolgus monkeys by repeated testing with steps of velocity about a vertical axis and adapted the gain of the VOR by altering visual input with magnifying and reducing lenses. After baseline values were established, the nodulus and ventral uvula of the vestibulocerebellum were ablated in

  11. Towards the Reflexive Medical School: The Hidden Curriculum and Medical Education Research.

    ERIC Educational Resources Information Center

    Cribb, Alan; Bignold, Sarah

    1999-01-01

    Suggests that the agenda and culture of reform in UK medical schools should be underpinned by more interpretive and reflexive research paradigms. Illustrates how the key tensions inherent in the professional socialization of doctors--between "objectifying" and "humanizing"--construct and limit both the capacity to change medical schools and the…

  12. Modulation of the visceromotor reflex by a lumbosacral ventral root avulsion injury and repair in rats

    PubMed Central

    Chang, Huiyi H.

    2012-01-01

    Increased abdominal muscle wall activity may be part of a visceromotor reflex (VMR) response to noxious stimulation of the bladder. However, information is sparse regarding the effects of cauda equina injuries on the VMR in experimental models. We studied the effects of a unilateral L6-S1 ventral root avulsion (VRA) injury and acute ventral root reimplantation (VRI) into the spinal cord on micturition reflexes and electromyographic activity of the abdominal wall in rats. Cystometrogram (CMG) and electromyography (EMG) of the abdominal external oblique muscle (EOM) were performed. All rats demonstrated EMG activity of the EOM associated with reflex bladder contractions. At 1 wk after VRA and VRI, the duration of the EOM EMG activity associated with reflex voiding was significantly prolonged compared with age-matched sham rats. However, at 3 wk postoperatively, the duration of the EOM responses remained increased in the VRA series but had normalized in the VRI group. The EOM EMG duration was normalized for both VRA and VRI groups at 8–12 wk postoperatively. CMG recordings show increased contraction duration at 1 and 3 wk postoperatively for the VRA series, whereas the contraction duration was only increased at 1 wk postoperatively for the VRI series. Our studies suggest that a unilateral lumbosacral VRA injury results in a prolonged VMR to bladder filling using a physiological saline solution. An acute root replantation decreased the VMR induced by VRA injury and provides earlier sensory recovery. PMID:22696606

  13. René Descartes. A study in the history of the theories of reflex action

    Microsoft Academic Search

    F. Fearing

    1929-01-01

    Descartes, more than any other man, is responsible for concepts of neuromuscular function which are acceptable in their major outlines to present-day physiologists. Detailed accounts, supplemented by quotations from his writings, are given of Descartes' views of automatic action, animal spirits, and reflex action. 11 references are given in the bibliography.

  14. Autoethnography as a Method for Reflexive Research and Practice in Vocational Psychology

    ERIC Educational Resources Information Center

    McIlveen, Peter

    2008-01-01

    This paper overviews the qualitative research method of autoethnography and its relevance to research in vocational psychology and practice in career development. Autoethnography is a reflexive means by which the researcher-practitioner consciously embeds himself or herself in theory and practice, and by way of intimate autobiographic account,…

  15. The relation of respiration and reflex winking rates to muscular tension during motor learning

    Microsoft Academic Search

    C. W. Telford; A. Storlie

    1946-01-01

    1. In a fairly difficult mirror-drawing-learning problem, time, errors, tension in the active hand, rate of reflex winking and respiration rate were recorded. 2. The time and error curves were typical of learning of this type. 3. The tension curve was \\

  16. Reflexivity as a Ground-Clearing Activity within the Context of Early Years' Pedagogy

    ERIC Educational Resources Information Center

    Jones, Liz

    2010-01-01

    The article concerns itself with the struggles that are prompted by the question, "What is my position as a teacher who whilst wanting to pursue emancipatory practices nevertheless is fearful of finding herself supporting and perpetuating normalizing structures?" An extract drawn from a journal entry serves as a base on which a series of reflexive

  17. Reflex neuromodulation of bladder function elicited by posterior tibial nerve stimulation in anesthetized rats.

    PubMed

    Kovacevic, Mario; Yoo, Paul B

    2015-02-15

    Although posterior tibial nerve stimulation (PTNS) has been shown in both clinical and animal studies to elicit bladder-inhibitory reflexes, our understanding of the role of posterior tibial nerve (PTN) afferents that elicit these responses is significantly limited. To this end, we investigated the effects of frequency-dependant PTNS in urethane-anesthetized rats undergoing repeated urodynamic fills. Nerve stimulation trials (10 min) resulted in statistically significant inhibition of the urinary bladder, both during and after nerve stimulation (P < 0.05). PTNS applied at 5 Hz resulted in both acute and prolonged changes that corresponded to 38.0% and 34.1% reductions in the bladder contraction frequency, respectively. In contrast, PTNS applied at 10 Hz could only elicit an acute decrease (22.9%) in bladder activity. Subsequent electrical activation of individual PTN branches (lateral or medial plantar nerves) confirmed that these bladder reflexes are mediated by specific subsets of the PTN trunk. Both acute and prolonged inhibition of the bladder were achieved by electrical stimulation of the lateral plantar (10 and 20 Hz) and medial plantar (5 and 10 Hz) nerves. Finally, we report a bladder-excitatory reflex that is elicited by electrical activation of either the PTN trunk or lateral plantar nerve at 50 Hz. This study shows that multiple bladder reflexes are tuned to specific subsets of nerve afferents and stimulation frequencies, each of which provide novel insights into the physiological effects of PTNS. PMID:25428124

  18. Maintaining Interaction at the Zone of Proximal Development through Reflexive Practice and Action Research

    ERIC Educational Resources Information Center

    Lisle, Angela

    2006-01-01

    In this study, dialectical reflexive practice is used to maintain student-teacher interactions in the zone of proximal development. The zone of proximal development is the development-and-learning unit of the child or learner and the author suggests that it is also the fusion point of Marx's dialectical historical materialism: the creation of…

  19. Bernard J. Baars I.P. Pavlov and the Freedom Reflex

    E-print Network

    Memphis, University of

    in San Diego. PICTURE OF PAVLOV TO BE SUPPLIED #12;Abstract: Why was Ivan Pavlevich Pavlov so widelyBernard J. Baars I.P. Pavlov and the Freedom Reflex We started off with a very simple experiment not remain quiet when it was constrained in the stand. I.P. Pavlov (1927, Vol. I, Ch. XXVIII) If `A

  20. For a public sociology on participatory democracy Reflexive feedback on a research conducted in an association

    E-print Network

    Boyer, Edmond

    1 For a public sociology on participatory democracy Reflexive feedback on a research conducted in an association Héloïse Nez (author's version) For a decade, research on participatory practices has proliferated on the relationships between research and action. However, the research conducted in collaboration with local actors

  1. The flexor reflex mediated by group II afferent fibers: effects of morphine-HCl and mephenesin.

    PubMed

    Sakitama, K; Ishikawa, M

    1992-10-01

    The effects of morphine-HCl and mephenesin on the flexor reflex mediated by group II afferent fibers were investigated. The flexor reflex was recorded by means of the electromyogram (EMG) evoked in the muscle tibialis anterior by stimulation of the ipsilateral tibial nerve in urethane-alpha-chloralose anesthetized rats. Afferent volleys corresponding to the phasic EMG component of the flexor reflex with 7.6-msec latency (flexor EMG: fEMG) were also recorded using the double volley technique. The threshold of the afferent volleys mediating the fEMG was approximately twice as high as that of the most excitable afferent volleys, which were considered the spikes of group I afferent fibers, and the conduction velocity of the afferent volleys was 39.9 +/- 3.2 m/sec. Morphine-HCl (5 mg/kg, i.v.) did not change the amplitude of the fEMG, but mephenesin (40 and 80 mg/kg, i.v.) depressed it dose-dependently. These results suggest that the fEMG is a flexor reflex mediated by group II afferent fibers, which is not affected by morphine-HCl but depressed by mephenesin. PMID:1479741

  2. Emergent Identity Matching after Successive Matching Training, I: Reflexivity or Generalized Identity?

    ERIC Educational Resources Information Center

    Urcuioli, Peter J.

    2011-01-01

    This research investigated the source of an ostensible reflexivity effect in pigeons reported by Sweeney and Urcuioli (2010). In Experiment 1, pigeons learned two symmetrically reinforced symbolic successive matching tasks (hue-form and form-hue) using red-green and triangle-horizontal line stimuli. They differed in their third concurrently…

  3. "Hearing the Country": Reflexivity as an Intimate Journey into Epistemological Liminalities

    ERIC Educational Resources Information Center

    Bradley, John

    2012-01-01

    In this article I discuss the way Problem-Based Learning (PBL) and reflexivity is employed in a university environment to address the question of how we can most successfully transfer knowledge about the presumed Other into our own cultural space without reducing, fragmenting, and exoticising complex knowledge systems. My goal is to stimulate in…

  4. Reflexive Orienting in Response to Eye Gaze and an Arrow in Children with and without Autism

    ERIC Educational Resources Information Center

    Senju, Atsushi; Tojo, Yoshikuni; Dairoku, Hitoshi; Hasegawa, Toshikazu

    2004-01-01

    Background: This study investigated whether another person's social attention, specifically the direction of their eye gaze, and a non-social directional cue, an arrow, triggered reflexive orienting in children with and without autism in an experimental situation. Methods: Children with autism and typically developed children participated in one…

  5. The Limits of Children's Voices: From Authenticity to Critical, Reflexive Representation

    ERIC Educational Resources Information Center

    Spyrou, Spyros

    2011-01-01

    This article provides a critique of the preoccupation with children's voices in child-centred research by exploring their limits and problematizing their use in research. The article argues that critical, reflexive researchers need to reflect on the processes which produce children's voices in research, the power imbalances that shape them and the…

  6. Using Stimulation of the Diving Reflex in Humans to Teach Integrative Physiology

    ERIC Educational Resources Information Center

    Choate, Julia K.; Denton, Kate M.; Evans, Roger G.; Hodgson, Yvonne

    2014-01-01

    During underwater submersion, the body responds by conserving O[subscript 2] and prioritizing blood flow to the brain and heart. These physiological adjustments, which involve the nervous, cardiovascular, and respiratory systems, are known as the diving response and provide an ideal example of integrative physiology. The diving reflex can be…

  7. Effects of Cultured Adrenal Chromaffin Cell Implants on Hindlimb Reflexes of the 6-OHDA Lesioned Rat

    PubMed Central

    Pulford, Bruce E.; Mihajlov, Andrea R.; Nornes, Howard O.; Whalen, L. Ray

    1994-01-01

    The effects of implantation of cultured adrenal medullary cells on the recovery of neurotransmitter specific reflex activity were studied in the rat spinal cord using electrophysiological testing methods. Cell suspensions of cultured neonatal adrenal medullary chromaffin (AM) cells (which produce catecholamines), or Schwann (Sc) cells (controls) were implanted into the lumbar region of the spinal cord 2 weeks after catecholamine (CA) denervation by intracisternal injection of 6-hydroxydopamine (6-OHDA). All cells were taken from 7 day neonates and cultured for 10 days in the presence of nerve growth factor (NGF). Three months after implantation, the extent of implant-associated recovery of reflex activity was determined by measuring electromyogram (EMG) activity and force associated with the long latency component of the hindlimb withdrawal reflex (which is CA modulated). After the electrophysiological testing, rats were anesthetized, and the spinal cords were rapidly removed and frozen. Spinal cords were sectioned longitudinally, and implanted cells were visualized using glyoxylic acid techniques. Labelled sections were examined to determine cell survival. Results indicate that 1) chromaffin cells survive for 3 months in the segments of the cord into which they have been implanted and 2) rats implanted with AM cells have significantly more forceful withdrawal reflexes than those that received Sc cells or received no implant after lesioning. PMID:7703294

  8. Dream Interpretation as a Component of Researcher's Reflexivity within an Ethnographic Research

    ERIC Educational Resources Information Center

    Miškolci, Jozef

    2015-01-01

    Researchers' "reflexivity" about how they shape the phenomena that they study within the data collection process is often presented as a crucial component of ethnographic research methodology. Nevertheless, academic literature about ethnography is mostly silent around whether researchers' dreams are relevant to the research…

  9. A reflexive approach to dealing with uncertainties in environmental health risk science and policy

    Microsoft Academic Search

    Matthieu Craye; Silvio Funtowicz; Jeroen P. Van Der Sluijs

    2005-01-01

    Based on insights obtained through an analysis of an environmental health risk controversy, we developed a reflexive approach to uncertainty assessment, explicitly acknowledging the complexity of the knowledge production process. The approach aims at interactively exploring uncertainty in relation to different scientific framings, societal perspectives and policy options. The structure of the discussion scheme used for the exploration is based

  10. Reflexivity and Professional Use of Self in Research: A Doctoral Student's Journey

    ERIC Educational Resources Information Center

    Valandra, V.

    2012-01-01

    In this analysis I reflected how research reflexivity and professional use of self assisted me in completing my phenomenological doctoral study about African American mothers' experiences of sexual mistreatment and how those experiences influence their child rearing practices within an extended family system. I combined research and social work…

  11. Identification of time-varying dynamics of the human triceps surae stretch reflex

    Microsoft Academic Search

    Robert F. Kirsch; Robert E. Kearney; J. Bart MacNeil

    1993-01-01

    We have examined the time variations of stretch reflex dynamics throughout rapid voluntary changes in the isometric contraction level of the human triceps surae muscles. This was achieved by superimposing a small stochastic displacement upon many such changing contractions and then identifying the time-varying relationship between the perturbation and the evoked electromyograms (EMGs). An “ensemble” time-varying system identification technique was

  12. Acoustic startle reflex in schizophrenia patients and their first-degree relatives: Evidence of

    E-print Network

    Curtis, Clayton

    Acoustic startle reflex in schizophrenia patients and their first-degree relatives: Evidence schizophrenia patients, 48 of their first-degree relatives, and 56 controls to determine if abnormal affective startle modulation could be associated with genetic risk for schizophrenia. Both patients and relatives

  13. The Reflexive Producer: The Influence of Farmer Knowledge upon the Use of Bt Corn

    ERIC Educational Resources Information Center

    Kaup, Brent Z.

    2008-01-01

    This paper examines the influence of farmer knowledge upon decision making processes. Drawing upon the sociological debates around the ideas of reflexive modernity and biotechnology as well as from classic adoption and diffusion studies, I explore the influences upon farmers' use of "Bacillus thuringiensis" (Bt) corn. Utilizing survey data…

  14. Practices for reflexive design: lessons from a Dutch programme on sustainable agriculture

    Microsoft Academic Search

    John Grin; Francisca Felix; A. P. Bos; Sierk Spoelstra

    2004-01-01

    Not coincidentally, deliberative policy analysis has been practiced often in cases that in a very essential sense involve value dissent and major uncertainties: cases of what Beck, Giddens and others have designated 'reflexive modernisation'. Deliberation, under such circumstances, is to support a synthesising kind of judgment across existing differentiations and distinctions, that is a process of judgement in which assumptions,

  15. A Limit to Reflexivity: The Challenge for Working Women of Negotiating Sharing of Household Labor

    ERIC Educational Resources Information Center

    Walters, Peter; Whitehouse, Gillian

    2012-01-01

    Unpaid household labor is still predominantly performed by women, despite dramatic increases in female labor force participation over the past 50 years. For this article, interviews with 76 highly skilled women who had returned to the workforce following the birth of children were analyzed to capture reflexive understandings of the balance of paid…

  16. Learners' Reflexivity and the Development of an E-Learning Community among Students in China

    ERIC Educational Resources Information Center

    Li, Zhen

    2011-01-01

    The experiences of Chinese learners on two e-learning programmes in China were investigated, focusing particularly on the formation of learning communities. Data were collected using a range of instruments to access the learners' perspectives in depth and detail. Archer's account of reflexivity as the mediating power between structure and agency…

  17. A Process of Becoming: In Favour of a Reflexive Narrative Approach

    ERIC Educational Resources Information Center

    Lyle, Ellyn

    2009-01-01

    As both researcher and practitioner, or in service educator, I often resist situating myself within one discrete tradition. For this reason, I turn to narrative as an approach to understanding. I believe employing narrative allows me to draw from a cross-section of scholarly work including reflexive inquiry, critical analysis, and autoethnography.…

  18. A MEANS TO ASSESS NURSING EFFICIENCY IN THE PIG: THE STUDY OF THE MILK EJECTION REFLEX

    E-print Network

    Paris-Sud XI, Université de

    A MEANS TO ASSESS NURSING EFFICIENCY IN THE PIG: THE STUDY OF THE MILK EJECTION REFLEX F will be followed by a discussion of incomplete nursing assessed by intramammary pressure changes. Intramammary considerably and possibly reducing sow-piglet interactions. Thus the assessment of behavioural activities

  19. An Existentialist in Iqaluit: Existentialism and Reflexivity Informing Pedagogy in the Canadian North

    ERIC Educational Resources Information Center

    Yue, Anthony R.

    2011-01-01

    Reflecting on the personal experience of teaching human resource management in the Canadian Arctic, the author explores the utility of an existentialist approach to pedagogy. The author outlines select aspects of existentialism that are pertinent to the teaching and discusses the implications of using reflexive existential thought as guidance in a…

  20. “Hypnopuncture”—A Dental-Emergency Treatment Concept for Patients with A Distinctive gag reflex

    Microsoft Academic Search

    Stephan Eitner; Manfred Wichmann; Stefan Holst

    2005-01-01

    The present case report describes a newly developed dental treatment concept for patients with a distinctive gag reflex. “Hypnopuncture” is a combination therapy of hypnosis and acupuncture. Its simple, fast, and effective application autonomous of the cause makes it a valuable tool for dental-emergency treatment procedures. Physiologic and psychological aspects of gagging are influenced at the same time. The protocol