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Sample records for conditioned reflexes

  1. [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

  2. 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…

  3. 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…

  4. Quantal organization of reflex and conditioned eyelid responses.

    PubMed

    Domingo, J A; Gruart, A; Delgado-García, J M

    1997-11-01

    Quantal organization of reflex and conditioned eyelid responses. J. Neurophysiol. 78: 2518-2530, 1997. Upper lid movements and the electromyographic activity of the orbicularis oculi muscle were recorded in behaving cats during spontaneous and experimentally evoked reflex blinks, and conditioned eyelid responses. Reflex blinks evoked by the presentation of air puffs, flashes, or tones consisted of a fast downward lid movement followed by late, small downward waves, recurring at approximately 50-ms intervals. The latency, maximum amplitude, peak velocity, and number of late waves depended on the modality, intensity, and duration of the evoking stimulus. The power spectra of acceleration records indicated a dominant frequency of approximately 20 Hz for air puff-evoked blinks. Flashes and tones usually evoked small and easily fatigable reflex responses of lower dominant frequencies (14-17 and 9-11 Hz, respectively). A basic approximately 20-Hz oscillation was also noticed during lid fixation, and ramplike lid displacements evoked by optokinetic stimuli. Five classical conditioning paradigms were used to analyze the frequency-domain properties of conditioned eyelid responses. These learned lid movements differed in latency, maximum amplitude, and profile smoothness depending on the modality (air puff, tone), intensity (weak, strong), and presentation site (ipsi-, contralateral to the unconditioned stimulus) of the conditioned stimulus. It was found that the characteristic ramplike profile of a conditioned response was not smooth, but appeared to be formed by a succession of small waves at a dominant frequency of approximately 20 Hz. The amplitude (and number) of the constituting waves depended on the characteristics of the conditioned stimulus and on the time interval until unconditioned stimulus presentation. Thus conditioned responses seemed to be formed from lid displacements of 2-6 degrees in amplitude and approximately 50 ms in duration, which increased in number throughout conditioning sessions, until a complete (i.e., lid closing) conditioned response was reached. It is suggested that a approximately 20-Hz oscillator underlies the generation of reflex and conditioned eyelid responses. The oscillator is susceptible to being neurally modulated to modify the velocity of a given quantum of movement, and the total duration of the lid response. Learned eyelid movements are probably the result of a successively longer release of the oscillator as a function of the temporal-spatial needs of the motor response. PMID:9356402

  5. Modulation of defensive reflex conditioning in snails by serotonin.

    PubMed

    Andrianov, Vyatcheslav V; Bogodvid, Tatiana K; Deryabina, Irina B; Golovchenko, Aleksandra N; Muranova, Lyudmila N; Tagirova, Roza R; Vinarskaya, Aliya K; Gainutdinov, Khalil L

    2015-01-01

    Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the "neurotoxic" analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the "neurotoxic" analogs of serotonin 5,6- and 5,7-dihydroxytryptamine as well as serotonin, depolarization of the membrane and decrease of the threshold potential of premotor interneurons was observed. We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the "neurotoxic" analogs of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT) were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within 2 weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail's ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3. PMID:26557063

  6. Modulation of defensive reflex conditioning in snails by serotonin

    PubMed Central

    Andrianov, Vyatcheslav V.; Bogodvid, Tatiana K.; Deryabina, Irina B.; Golovchenko, Aleksandra N.; Muranova, Lyudmila N.; Tagirova, Roza R.; Vinarskaya, Aliya K.; Gainutdinov, Khalil L.

    2015-01-01

    Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the “neurotoxic” analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the “neurotoxic” analogs of serotonin 5,6- and 5,7-dihydroxytryptamine as well as serotonin, depolarization of the membrane and decrease of the threshold potential of premotor interneurons was observed. We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the “neurotoxic” analogs of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT) were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within 2 weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail's ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3. PMID:26557063

  7. The second modern condition? Compressed modernity as internalized reflexive cosmopolitization.

    PubMed

    Kyung-Sup, Chang

    2010-09-01

    Compressed modernity is a civilizational condition in which economic, political, social and/or cultural changes occur in an extremely condensed manner in respect to both time and space, and in which the dynamic coexistence of mutually disparate historical and social elements leads to the construction and reconstruction of a highly complex and fluid social system. During what Beck considers the second modern stage of humanity, every society reflexively internalizes cosmopolitanized risks. Societies (or their civilizational conditions) are thereby being internalized into each other, making compressed modernity a universal feature of contemporary societies. This paper theoretically discusses compressed modernity as nationally ramified from reflexive cosmopolitization, and, then, comparatively illustrates varying instances of compressed modernity in advanced capitalist societies, un(der)developed capitalist societies, and system transition societies. In lieu of a conclusion, I point out the declining status of national societies as the dominant unit of (compressed) modernity and the interactive acceleration of compressed modernity among different levels of human life ranging from individuals to the global community. PMID:20840427

  8. Gutkha Addiction: Nicotine Dependence or a Conditioned Reflex?

    PubMed Central

    Joshi, Prathamesh Satish; Prashant, M C; Nagpal, Neelu; Patil, Atulkumar A; Ahuja, Rinky; Mathur, Vidhi

    2015-01-01

    Background: A pre-packaged mixture of areca nut, tobacco, slaked lime, catechu, and flavoring agents is popularly known as Gutkha. Aim of study is to analyze the addiction biology of Gutkha chewing and to assess efficacy of a cessation program based on nicotine replacement therapy (NRT). Materials and Methods: Patterns of addiction of 400 Gutkha chewers were analyzed with a questionnaire-based survey. Urine cotinine levels of 60 subjects undergoing NRT were periodically estimated using gas chromatography. Results: Mean urine cotinine levels of relapse and relapse-free cases were 5800.38 µg/g of creatine and 5622.16 µg/g of creatine. The difference was not found to be statistically significant. A 83.3% of the subjects associated their chewing habit with day to day activities. Overall relapse rate was found to be 79%. The most common reported reason for relapse was unacceptable taste and form of nicotine chewing gums. Conclusion: Repetitive coexistence in time of an indifferent act and the act of chewing Gutkha where, the act of chewing is almost always preceded by the indifferent act sets in a conditioned reflex. Gutkha addiction can be considered as a form of conditioned reflex, rather than actual craving for nicotine.

  9. Induced specific immunological unresponsiveness & conditioned behavioral reflexes, in functional isomorphism-meditation and conditioned specific unresponsiveness.

    PubMed

    Freed, S

    1989-02-01

    Detailed functional isomorphism had been observed (Freed, 1984) between induced (conditioned) immunogenicity and classical conditioned defensive reflexes, possibly as evolutionary adaptation against danger at micro and macro levels respectively. Similarly, functional isomorphism is postulated between conditioned specific tolerogenicity of the immunotolerance system and behavioral reflexes. Isomorphism requires that sensory signals elaborated with intrinsic (unconditioned) behavioral tolerogens as carriers do not subsequently combine classically with unconditioned aversive stimuli and evoke conditioned defensive responses. Unconditioned behavioral tolerogenic carriers were identified with behavioral (physiological) activities of Oriental meditation. Confirmation of conditioned behavioral tolerogenicity appeared in the unresponsiveness of Yogi mediators to sensory stimuli as reflected in unchanged alpha rhythms of their encephalograms. Conditioned behavioral specific unresponsiveness maintains the "quiet" of meditation and mediates the experience of Zen mediators, namely, sharpened, clearer perceptions and unresponsiveness to aversive components of current conditioned signals ordinarily reactivating residues of affect. Conditioned behavioral specific unresponsiveness has survival value. PMID:2656566

  10. Visual conditioning of the sting extension reflex in harnessed honeybees.

    PubMed

    Mota, Theo; Roussel, Edith; Sandoz, Jean-Christophe; Giurfa, Martin

    2011-11-01

    Visual performances of honeybees have been extensively studied using free-flying individuals trained to choose visual stimuli paired with sucrose reward. By contrast, harnessed bees in the laboratory were not thought to be capable of learning a Pavlovian association between a visual stimulus (CS) and sucrose reward (US). For reasons as yet unknown, harnessed bees only learn visual cues in association with sucrose if their antennae are ablated. However, slow acquisition and low retention performances are obtained in this case. Here, we established a novel visual conditioning protocol, which allows studying visual learning and memory in intact harnessed bees in the laboratory. This protocol consists of conditioning the sting extension reflex (SER) by pairing a visual stimulus (CS+) with an electric shock punishment (US), and a different visual stimulus (CS-) with the absence of shock. Bees with intact antennae learned the discrimination between CS+ and CS- by using chromatic cues, achromatic cues or both. Antennae ablation was not only unnecessary for learning to occur but it even impaired visual SER conditioning because of a concomitant reduction of responsiveness to the electric shock. We thus established the first visual conditioning protocol on harnessed honeybees that does not require injuring the experimental subjects. This novel experimental approach opens new doors for accessing the neural correlates of visual learning and memory in honeybees. PMID:21993786

  11. [Influence of transcranial electromagnetic brain stimulation on development of conditioned reflex in rats].

    PubMed

    Samoilov, V O; Shadrin, E B; Filippova, E B; Katsnelson, Ya; Backhoff, H; Eventov, M

    2015-01-01

    The influence of transcranial electromagnetic stimulation on the development of an active avoidance reflex with painful reinforcement in laboratory rats is investigated. It is shown, that an exposure of the rats' brain to electromagnetic radiation in the millimeter range ((? = 5,6 and 7,1 mm), modulated as a series of low-frequency pulses, leads to a suppression of the development of the conditioned avoidance reflex occurred in 50% of cases. In other 25% of cases irradiation leads to inhibition of reflex development. Transcranial electromagnetic stimulation after intraperitoneal injection of the blocking agent of serotonergic receptors (kitryl) has no influence on reflex development. Electromagnetic brain stimulation does not influence reflex retention in the case when it has been acquired. Based on the data obtained it is assumed that transcranial electromagnetic stimulation promotes the development of serotonin, exerting an inhibiting effect on the formation of temporal bindings of the studied conditioned reflex. PMID:26016036

  12. 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

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

    PubMed

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

    2014-03-01

    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

  14. Restoring walking after spinal cord injury: operant conditioning of spinal reflexes can help.

    PubMed

    Thompson, Aiko K; Wolpaw, Jonathan R

    2015-04-01

    People with incomplete spinal cord injury (SCI) frequently suffer motor disabilities due to spasticity and poor muscle control, even after conventional therapy. Abnormal spinal reflex activity often contributes to these problems. Operant conditioning of spinal reflexes, which can target plasticity to specific reflex pathways, can enhance recovery. In rats in which a right lateral column lesion had weakened right stance and produced an asymmetrical gait, up-conditioning of the right soleus H-reflex, which increased muscle spindle afferent excitation of soleus, strengthened right stance and eliminated the asymmetry. In people with hyperreflexia due to incomplete SCI, down-conditioning of the soleus H-reflex improved walking speed and symmetry. Furthermore, modulation of electromyographic activity during walking improved bilaterally, indicating that a protocol that targets plasticity to a specific pathway can trigger widespread plasticity that improves recovery far beyond that attributable to the change in the targeted pathway. These improvements were apparent to people in their daily lives. They reported walking faster and farther, and noted less spasticity and better balance. Operant conditioning protocols could be developed to modify other spinal reflexes or corticospinal connections; and could be combined with other therapies to enhance recovery in people with SCI or other neuromuscular disorders. PMID:24636954

  15. On the functional stucture of conditioned reflexes to serial stimuli in dogs.

    PubMed

    Rudenko, L P

    1974-01-01

    The functional structure of conditioned reflexes to a stimulus series has been studied. The serial stimulus consisted of a tone of 600 Hz, passive lifting of the right forepaw, and a puff of air directed at the eye, the latter component of the series being reinforced by food. Four dogs were wed. Objective registration of the effector manifestations to each component stimulus has shown that, during the elaboration of a conditioned alimentary reflex to the serial stimulus, conditioned connections are formed by each component with the alimentary center and by each preceding stimulus with all subsequent stimuli, irrespective of their position in the series. All excitation foci which function in the given stimulus set become interconnected. Direct connections of each stimulus component with the alimentary center are never inhibited. The multiplicity of duplicating direct connections and the presence of backward connections impart to composite reflexes the reliability and adaptive strength which is necessary for the formation of behavioral acts. PMID:4838076

  16. Kinetic and frequency-domain properties of reflex and conditioned eyelid responses in the rabbit.

    PubMed

    Gruart, A; Schreurs, B G; del Toro, E D; Delgado-García, J M

    2000-02-01

    Eyelid position and the electromyographic activity of the orbicularis oculi muscle were recorded unilaterally in rabbits during reflex and conditioned blinks. Air-puff-evoked blinks consisted of a fast downward phase followed sometimes by successive downward sags. The reopening phase had a much longer duration and slower peak velocity. Onset latency, maximum amplitude, peak velocity, and rise time of reflex blinks depended on the intensity and duration of the air puff-evoking stimulus. A flashlight focused on the eye also evoked reflex blinks, but not flashes of light, or tones. Both delayed and trace classical conditioning paradigms were used. For delayed conditioning, animals were presented with a 350-ms, 90-dB, 600-Hz tone, as conditioned stimulus (CS). For trace conditioning, animals were presented with a 10-ms, 1-k/cm(2) air puff, as CS. The unconditioned stimulus (US) consisted of a 100-ms, 3-k/cm(2) air puff. The stimulus interval between CS and US onsets was 250 ms. Conditioned responses (CRs) to tones were composed of downward sags that increased in number through the successive conditioning sessions. The onset latency of the CR decreased across conditioning at the same time as its maximum amplitude and its peak velocity increased, but the time-to-peak of the CR remained unaltered. The topography of CRs evoked by short, weak air puffs as the CS showed three different components: the alpha response to the CS, the CR, and the reflex response to the US. Through conditioning, CRs showed a decrease in onset latency, and an increase in maximum amplitude and peak velocity. The time-to-peak of the CR remained unchanged. A power spectrum analysis of reflex and conditioned blink acceleration profiles showed a significant approximately 8-Hz oscillation within a broadband of frequencies between 4 and 15 Hz. Nose and mandible movements presented power spectrum profiles different from those characterizing reflex and conditioned blinks. It is concluded that eyelid reflex responses in the rabbit present significant differences from CRs in their profiles and metric properties, suggesting different neural origins, but that a common approximately 8-Hz neural oscillator underlies lid motor performance. According to available data, the frequency of this putative oscillator seems to be related to the species size. PMID:10669498

  17. 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

  18. Infant reflexes

    MedlinePLUS

    ... neck reflex; Galant reflex; Truncal incurvation; Rooting reflex; Parachute reflex; Grasp reflex ... was stroked and begin to make sucking motions. Parachute reflex . This reflex occurs in slightly older infants ...

  19. Effects of Extinction on Classical Conditioning and Conditioning-Specific Reflex Modification of Rabbit Heart Rate

    PubMed Central

    Burhans, Lauren B.; Smith-Bell, Carrie; Schreurs, Bernard G.

    2009-01-01

    Understanding the mechanisms of fear extinction has become increasingly important for treating a number of disorders, particularly post-traumatic stress disorder. Conditioning of rabbit heart rate (HR) is an established model for studying fear, yet little is known about procedures for extinguishing it other than repeated presentations of cue(s) associated with the fear-inducing event. The following study examined the effects of conditioned stimulus (CS) alone, unconditioned stimulus (US) alone, unpaired CS/US presentations, continued CS-US pairings, or no further stimulation on rabbit HR following HR conditioning. We have previously shown the rabbit HR response to the US can change as a function of learning when measured in the absence of the CS, a phenomenon referred to as conditioning-specific reflex modification (CRM). More specifically, the HR exhibits a deceleration in response to the US reminiscent of the conditioned bradycardia that develops to the CS. Consequently, the following study also examined the effects of extinction treatments on HR CRM. For HR conditioned responses (CRs), CS-alone and unpaired CS/US presentations were the most successful extinction treatments. For HR CRM, all conditions led to a reduction in CRM except for a subset of rabbits that maintained high levels following unpaired extinction, indicating a dissociation between extinction of HR CRs and CRM. The findings highlight the parameters of HR extinction, the transient nature of HR CRM, vagal involvement in both acquisition and extinction of HR CRM, and suggest that HR CRM cannot be fully explained as a CR that has generalized from the CS to the US. PMID:19747508

  20. Effects of extinction on classical conditioning and conditioning-specific reflex modification of rabbit heart rate.

    PubMed

    Burhans, Lauren B; Smith-Bell, Carrie; Schreurs, Bernard G

    2010-01-01

    Understanding the mechanisms of fear extinction has become increasingly important for treating a number of disorders, particularly post-traumatic stress disorder. Conditioning of rabbit heart rate (HR) is an established model for studying fear, yet little is known about procedures for extinguishing it other than repeated presentations of cue(s) associated with the fear-inducing event. The following study examined the effects of conditioned stimulus (CS) alone, unconditioned stimulus (US) alone, unpaired CS/US presentations, continued CS-US pairings, or no further stimulation on rabbit HR following HR conditioning. We have previously shown the rabbit HR response to the US can change as a function of learning when measured in the absence of the CS, a phenomenon referred to as conditioning-specific reflex modification (CRM). More specifically, the HR exhibits a deceleration in response to the US reminiscent of the conditioned bradycardia that develops to the CS. Consequently, the following study also examined the effects of extinction treatments on HR CRM. For HR conditioned responses (CRs), CS-alone and unpaired CS/US presentations were the most successful extinction treatments. For HR CRM, all conditions led to a reduction in CRM except for a subset of rabbits that maintained high levels following unpaired extinction, indicating a dissociation between extinction of HR CRs and CRM. The findings highlight the parameters of HR extinction, the transient nature of HR CRM, vagal involvement in both acquisition and extinction of HR CRM, and suggest that HR CRM cannot be fully explained as a CR that has generalized from the CS to the US. PMID:19747508

  1. Operant conditioning of the soleus H-reflex does not induce long-term changes in the gastrocnemius H-reflexes and does not disturb normal locomotion in humans

    PubMed Central

    Makihara, Yukiko; Segal, Richard L.; Wolpaw, Jonathan R.

    2014-01-01

    In normal animals, operant conditioning of the spinal stretch reflex or the H-reflex has lesser effects on synergist muscle reflexes. In rats and people with incomplete spinal cord injury (SCI), soleus H-reflex operant conditioning can improve locomotion. We studied in normal humans the impact of soleus H-reflex down-conditioning on medial (MG) and lateral gastrocnemius (LG) H-reflexes and on locomotion. Subjects completed 6 baseline and 30 conditioning sessions. During conditioning trials, the subject was encouraged to decrease soleus H-reflex size with the aid of visual feedback. Every sixth session, MG and LG H-reflexes were measured. Locomotion was assessed before and after conditioning. In successfully conditioned subjects, the soleus H-reflex decreased 27.2%. This was the sum of within-session (task dependent) adaptation (13.2%) and across-session (long term) change (14%). The MG H-reflex decreased 14.5%, due mainly to task-dependent adaptation (13.4%). The LG H-reflex showed no task-dependent adaptation or long-term change. No consistent changes were detected across subjects in locomotor H-reflexes, EMG activity, joint angles, or step symmetry. Thus, in normal humans, soleus H-reflex down-conditioning does not induce long-term changes in MG/LG H-reflexes and does not change locomotion. In these subjects, task-dependent adaptation of the soleus H-reflex is greater than it is in people with SCI, whereas long-term change is less. This difference from results in people with SCI is consistent with the fact that long-term change is beneficial in people with SCI, since it improves locomotion. In contrast, in normal subjects, long-term change is not beneficial and may necessitate compensatory plasticity to preserve satisfactory locomotion. PMID:24944216

  2. Operant conditioning of H-reflex changes synaptic terminals on primate motoneurons.

    PubMed Central

    Feng-Chen, K C; Wolpaw, J R

    1996-01-01

    Operant conditioning of the primate triceps surae H-reflex, the electrical analog of the spinal stretch reflex, creates a memory trace that includes changes in the spinal cord. To define the morphological correlates of this plasticity, we analyzed the synaptic terminal coverage of triceps surae motoneurons from animals in which the triceps surae H-reflex in one leg had been increased (HRup mode) or decreased (HRdown mode) by conditioning and compared them to each other and to motoneurons from unconditioned animals. Motoneurons were labeled by intramuscular injection of cholera toxin-horseradish peroxidase. A total of 5055 terminals on the cell bodies and proximal dendrites of 114 motoneurons from 14 animals were studied by electron microscopy. Significant differences were found between HRup and HRdown animals and between HRup and naive (i.e., unconditioned) animals. F terminals (i.e., putative inhibitory terminals) were smaller and their active zone coverage on the cell body was lower on motoneurons from the conditioned side of HRup animals than on motoneurons from the conditioned side of HRdown animals. C terminals (i.e., terminals associated with postsynaptic cisterns and rough endoplasmic reticulum) were smaller and the number of C terminals in each C complex (i.e., a group of contiguous C terminals) was larger on motoneurons from the conditioned side of HRup animals than on motoneurons either from the conditioned side of HRdown animals or from naive animals. Because the treatment of HRup and HRdown animals differed only in the reward contingency, the results imply that the two contingencies had different effects on motoneuron synaptic terminals. In combination with other recent data, they show that H-reflex conditioning produces a complex pattern of spinal cord plasticity that includes changes in motoneuron physiological properties as well as in synaptic terminals. Further delineation of this pattern should reveal the contribution of the structural changes described here to the learned change in behavior. Images Fig. 2 Fig. 4 PMID:8799179

  3. Protein synthesis-dependent reactivation of a contextual conditioned reflex in the common snail.

    PubMed

    Gainutdinova, T Kh; Tagirova, R R; Ismailova, A I; Muranova, L N; Gainutdinov, Kh L; Balaban, P M

    2006-02-01

    We report here a study of the effects of blockade of protein synthesis with anisomycin during reactivation of a contextual conditioned reflex in the common snail. The amplitudes of the defensive reactions of snails to standard tactile stimulation before training were identical in two conditions: 1) testing of responses of snails fixed by the shell to a plastic ball floating in water and 2) on the surface of the terrarium glass. After applying electric shocks to the snails' skin for 5 days, a significant difference in responses reflecting the formation of a contextual conditioned reflex was seen in only one of the contexts. Placing trained snails in the same context (reminding) two days after training with simultaneous injection of anisomycin led to significant weakening of training, while control injections of physiological saline produced no such changes. These data suggest that the mechanisms of memory consolidation after training and reminding are not identical. PMID:16380834

  4. 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

  5. Reflexes in psychiatry.

    PubMed

    Sanders, Richard D; Gillig, Paulette Marie

    2011-04-01

    Psychiatric patients often do not cooperate fully with the neurologic examination. Reflexes virtually bypass patient effort and are difficult to consciously determine. This article reviews muscle stretch (deep tendon) reflexes, and pathological reflexes including the extensor plantar (Babinski) and primitive release reflexes. Topics include findings in common psychiatric and neurologic conditions and methods for eliciting these signs. PMID:21637631

  6. 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…

  7. 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…

  8. [The effect of bemitil on conditioned-reflex memory in normal rats and under stress exposures].

    PubMed

    Pragina, L L; Tushmalova, N A; Inozemtsev, A N; Smirnov, A V

    1999-01-01

    The authors studied the effect of the actoprotector bemitil on the conditional-reflex memory of rats and its functional disorder by disturbance of the cause-effect (abatement of the avoidance reaction) or space relations. Intraperitoneal injections of 1.8 mg/kg of bemitil were given daily 30 min before the experiment. The training of animals improved authentically from experiment to experiment. Thus, the drug, possesses the nootropic properties. Exposure to stressogenic factors of various depth demonstrated the stress-protective effect of bemitil. PMID:10513327

  9. Adaptation of the macular vestibuloocular reflex to altered gravitational conditions in a fish ( Oreochromis mossambicus)

    NASA Astrophysics Data System (ADS)

    Horn, E.; Sebastian, C.

    Young fish ( Oreochromis mossambicus) were exposed to microgravity (?g) for 9 to 10 days, or to hypergravity (hg) for 9 days. For several weeks after termination of ?g and hg, the roll-induced static vestibuloocular reflex (rVOR) was recorded. In stage 11/12-fish, the rVOR amplitude (angle between the maximal up and down movement of an eye during a complete 360° lateral roll) of ?g-animals increased significantly by 25% compared to 1g-controls during the first post-flight week but decreased to the control level during the second post-flight week. Microgravity had no effect in stage 14/16 fish on the rVOR amplitude. After 3g-exposure, the rVOR amplitude was significantly reduced for both groups compared to their 1g-controls. Readaptation to 1g-condition was completed during the second post-3g week. We postulate a critical period during which the development of the macular vestibuloocular reflex depends on gravitational input, and which is limited by the first appearence of the rVOR. At this period of early development, exposure to microgravity sensitizes the vestibular system while hypergravity desensitizes it.

  10. Adaptation of the macular vestibuloocular reflex to altered gravitational conditions in a fish (Oreochromis mossambicus).

    PubMed

    Horn, E; Sebastian, C

    2002-01-01

    Young fish (Oreochromis mossambicus) were exposed to microgravity (micro g) for 9 to 10 days, or to hypergravity (hg) for 9 days. For several weeks after termination of micro g and hg, the roll-induced static vestibuloocular reflex (rVOR) was recorded. In stage 11/12-fish, the rVOR amplitude (angle between the maximal up and down movement of an eye during a complete 360 degree lateral roll) of micro g-animals increased significantly by 25% compared to 1 g-controls during the first post-flight week but decreased to the control level during the second post-flight week. Microgravity had no effect in stage 14/16 fish on the rVOR amplitude. After 3 g-exposure, the rVOR amplitude was significantly reduced for both groups compared to their 1 g-controls. Readaptation to 1 g-condition was completed during the second post-3 g week. We postulate a critical period during which the development of the macular vestibuloocular reflex depends on gravitational input, and which is limited by the first appearance of the rVOR. At this period of early development, exposure to microgravity sensitizes the vestibular system while hypergravity desensitizes it. PMID:12528668

  11. 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

  12. Moro reflex

    MedlinePLUS

    Startle response; Startle reflex; Embrace reflex ... Your baby's doctor will check for this reflex right after birth and during well-child visits. To see the Moro reflex, the child will be placed face up on a soft, ...

  13. Amplification of interlimb reflexes evoked by stimulating the hand simultaneously with conditioning from the foot during locomotion

    PubMed Central

    2013-01-01

    Background Widespread interlimb reflexes evoked in leg muscles by cutaneous stimulation of the hand are phase-modulated and behaviorally relevant to produce functional changes in ankle trajectory during walking. These reflexes are complementary to the segmental responses evoked by stimulation at the ankle. Despite differences in the expression of reflex amplitude based upon site of nerve stimulation, there are some common features as well, suggesting the possibility of shared interneuronal pathways. Currently little is known about integration or shared reflex systems from interlimb cutaneous networks during human locomotion. Here we investigated convergent reflex effects following cutaneous stimulation of the hand and foot during arm and leg cycling (AL) by using spatial facilitation. Participants performed AL cycling and static activation of the target muscle knee extensor vastus lateralis (VL) in 3 different randomly ordered nerve stimulation conditions: 1) superficial radial nerve (SR; input from hand); 2) superficial peroneal nerve (SP; input from foot); and, 3) combined stimulation (SR + SP). Stimuli were applied around the onset of rhythmic EMG bursts in VL corresponding to the onset of the power or leg extension phase. Results During AL cycling, small inhibitory (~80 ms) and large facilitatory reflexes (~100?~?150 ms) were seen in VL. The amplitudes of the facilitatory responses with SR + SP stimulation were significantly larger than those for SP or SR stimulation alone. The facilitation was also significantly larger than the simple mathematical summation of amplitudes from SP and SR trials. This indicates extra facilitation beyond what would be accounted for by serial neuronal processing and was not observed during static activation. Conclusions We conclude that AL cycling activates shared interneurons in convergent reflex pathways from cutaneous inputs innervating the hand and leg. This enhanced activity has functional implications for corrective responses during locomotion and for translation to rehabilitation after neurotrauma. PMID:23497331

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

    PubMed Central

    2011-01-01

    Background Autonomous reflexes enable animals to respond quickly to potential threats, prevent injury and mediate fight or flight responses. Intense acoustic stimuli with sudden onsets elicit a startle reflex while stimuli of similar intensity but with longer rise times only cause a cardiac defence response. In laboratory settings, habituation appears to affect all of these reflexes so that the response amplitude generally decreases with repeated exposure to the stimulus. The startle reflex has become a model system for the study of the neural basis of simple learning processes and emotional processing and is often used as a diagnostic tool in medical applications. However, previous studies did not allow animals to avoid the stimulus and the evolutionary function and long-term behavioural consequences of repeated startling remain speculative. In this study we investigate the follow-up behaviour associated with the startle reflex in wild-captured animals using an experimental setup that allows individuals to exhibit avoidance behaviour. Results We present evidence that repeated elicitation of the acoustic startle reflex leads to rapid and pronounced sensitisation of sustained spatial avoidance behaviour in grey seals (Halichoerus grypus). Animals developed rapid flight responses, left the exposure pool and showed clear signs of fear conditioning. Once sensitised, seals even avoided a known food source that was close to the sound source. In contrast, animals exposed to non-startling (long rise time) stimuli of the same maximum sound pressure habituated and flight responses waned or were absent from the beginning. The startle threshold of grey seals expressed in units of sensation levels was comparable to thresholds reported for other mammals (93 dB). Conclusions Our results demonstrate that the acoustic startle reflex plays a crucial role in mediating flight responses and strongly influences the motivational state of an animal beyond a short-term muscular response by mediating long-term avoidance. The reflex is therefore not only a measure of emotional state but also influences emotional processing. The biological function of the startle reflex is most likely associated with mediating rapid flight responses. The data indicate that repeated startling by anthropogenic noise sources might have severe effects on long-term behaviour. Future, studies are needed to investigate whether such effects can be associated with reduced individual fitness or even longevity of individuals. PMID:21489285

  15. 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...

  16. Impaired acquisition of classically conditioned fear-potentiated startle reflexes in humans with focal bilateral basolateral amygdala damage.

    PubMed

    Klumpers, Floris; Morgan, Barak; Terburg, David; Stein, Dan J; van Honk, Jack

    2015-09-01

    Based on studies in rodents, the basolateral amygdala (BLA) is considered a key site for experience-dependent neural plasticity underlying the acquisition of conditioned fear responses. In humans, very few studies exist of subjects with selective amygdala lesions and those studies have only implicated the amygdala more broadly leaving the role of amygdala sub-regions underexplored. We tested a rare sample of subjects (N = 4) with unprecedented focal bilateral BLA lesions due to a genetic condition called Urbach-Wiethe disease. In a classical delay fear conditioning experiment, these subjects showed impaired acquisition of conditioned fear relative to a group of matched control subjects (N = 10) as measured by fear-potentiation of the defensive eye-blink startle reflex. After the experiment, the BLA-damaged cases showed normal declarative memory of the conditioned association. Our findings provide new evidence that the human BLA is essential to drive fast classically conditioned defensive reflexes. PMID:25552573

  17. [Protein synthesis-dependent reactivation of environmental conditioned reflex in terrestrial snails].

    PubMed

    Ga?nutdinova, T Kh; Tagirova, R R; Ismailova, A I; Muranova, L N; Ga?nutdinov, Kh L; Balaban, P M

    2004-01-01

    We investigated influence of anisomycine injection on reconsolidation of contextual memory after development of environmental conditioned reflex in terrestrial snail Helix. Testing the amplitude of behavioral reactions (tentacle withdrawal) in response to standard tactile stimulation of the skin in two contexts: a) when the snail was fixed by the shell and was moving on the surface of the ball floating in water, or b) was moving on the flat surface of glass terrarium, has shown no difference in response amplitudes. After a session of electric shocks (5 days) in one context only (ball) the associative learning was clearly observed as the significant difference of response amplitudes in two contexts. On the other day following testing was performed a session of "reminding", immediately after which the snails were injected by anisomycine (control snails were injected by saline solution). Testing has shown that injection of anisomycine led to impairment of the context conditioning. Results suggest that the mechanisms of consolidation of new memory and memory reconsolidation after retrieval are not identical. PMID:15658044

  18. 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

  19. The grasp reflex and moro reflex in infants: hierarchy of primitive reflex responses.

    PubMed

    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

  20. [Effects of mechanical stimulation of the soles' support zones on H-reflex characteristics under support unloading condition].

    PubMed

    Zakirova, A Z; Shigueva, T A; Tomilovskaya, E S; Kozlovskaya, I B

    2015-01-01

    The aim of the work was to study the effects of mechanical stimulation of the soles' support zones on state of m. soleus motoneurone pool in man under 7-days support unloading conditions, which was provided by "Dry Immersion" model. Before, during and after immersion exposure the excitability of m. soleus motoneurone pool was estimated by H-reflex amplitude normalized by the maximal amplitude of M-wave. The data registered in two groups of volunteers: "control" in which only immersion exposure was used and "experimental" in which stimulation of support zones of sole was carried out during Dry Immersion were compared. During immersion relative amplitude of H-reflex increased in the control group. These alterations were not revealed in the experimental group with daily application of the support stimulation in natural locomotion regimens during immersion. PMID:26027332

  1. [The Interaction of the Medial Prefrontal Cortex, Ventral Hippocampus and Basolateral Amygdala in the Course of Performance of Conditioned Avoidance Reflex].

    PubMed

    Serkov, A N; Serkova, V V; Maiorov, V I

    2015-01-01

    The interaction (synchronization) of activity of the medial prefrontal cortex, hippocampus and basolateral amygdala have been studied in the course of performance of conditioned avoidance reflex. The pre-stimulus expectation period was characterized by low-frequency delta-activity (1-4 Hz) with the source (according to criteria of Granger causality) in the prefrontal cortex and also by synchronized theta-rhythm (6-8 Hz) in the hippocampus. The performance of conditioned avoidance reflex was characterized by generation of high-frequency synchronized theta-rhythm (8-11 Hz) simultaneously with delta-activity elimination. The phase of delta- (theta-) activity modulates the envelope of gamma-rhythm (~30-120 Hz) in each of the structures. The elaboration and strengthening of conditioned reflex leads to concurrent theta power and synchronization growth in relation to reflex performance, but not during the prestimulus expectation period. PMID:26080601

  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. Inactivation of interposed nuclei in the cat: classically conditioned withdrawal reflexes, voluntary limb movements and the action primitive hypothesis.

    PubMed

    Bracha, V; Kolb, F P; Irwin, K B; Bloedel, J R

    1999-05-01

    The cerebellar interposed nuclei are considered critical components of circuits controlling the classical conditioning of eyeblink responses in several mammalian species. The main purpose of the present experiments was to examine whether the interposed nuclei are also involved in the control of classically conditioned withdrawal responses in other skeletomuscular effector systems. To achieve this objective, a unique learning paradigm was developed to examine classically conditioned withdrawal responses in three effector systems (the eyelid, forelimb and hindlimb) in individual cats. Trained animals were injected with muscimol in the cerebellar interposed nuclei, and the effects on the three conditioned responses (CRs) were examined. Although the effects of muscimol were less dramatic than previously reported in the rabbit eyeblink preparation, the inactivation of the cerebellar nuclei affected the performance of CRs in all three effector systems. In additional experiments, animals were injected with muscimol at the sites affecting classically conditioned withdrawal responses to determine the effects of these injections on reaching and locomotion behaviors. These tests demonstrated that the same regions of the cerebellar interposed nuclei which control withdrawal reflexes are also involved in the control of limb flexion and precision placement of the paw during both locomotion and reaching tasks. The obtained data indicate that the interposed nuclei are involved in the control of ipsilateral action primitives and that inactivating the interposed nuclei affects several modes of action of these functional units. PMID:10333009

  4. Phase-dependent reversal of the crossed conditioning effect on the soleus Hoffmann reflex from cutaneous afferents during walking in humans.

    PubMed

    Suzuki, Shinya; Nakajima, Tsuyoshi; Futatsubashi, Genki; Mezzarane, Rinaldo A; Ohtsuka, Hiroyuki; Ohki, Yukari; Komiyama, Tomoyoshi

    2016-02-01

    We previously demonstrated that non-noxious electrical stimulation of the cutaneous nerve innervating the contralateral foot modified the excitability of the Hoffmann (H-) reflex in the soleus muscle (SOL) in a task-dependent manner during standing and walking in humans. To date, however, it remains unclear how the crossed conditioning effect on the SOL H-reflex from the contralateral foot is modified during the various phases of walking. We sought to answer this question in the present study. The SOL H-reflex was evoked in healthy volunteers by an electrical test stimulation (TS) of the right (ipsilateral) posterior tibial nerve at five different phases during treadmill walking (4 km/h). A non-noxious electrical stimulation was delivered to the superficial peroneal nerve of the left (contralateral) ankle ~100 ms before the TS as a conditioning stimulation (CS). This CS significantly suppressed the H-reflex amplitude during the early stance phase, whereas the same CS significantly facilitated the H-reflex amplitude during the late stance phase. The CS alone did not produce detectable changes in the full-wave rectified electromyogram of the SOL. This result indicates that presynaptic mechanisms driven by the activation of low-threshold cutaneous afferents in the contralateral foot play a role in regulating the transmission between the Ia terminal and motoneurons in a phase-dependent manner. The modulation pattern of the crossed conditioning effect on the SOL H-reflex may be functionally relevant for the left-right coordination of leg movements during bipedal walking. PMID:26573576

  5. Primitive reflexes in Parkinson's disease.

    PubMed Central

    Vreeling, F W; Verhey, F R; Houx, P J; Jolles, J

    1993-01-01

    A standardised protocol for the examination of 15 primitive reflexes in which the amplitude and the persistence were scored separately, was applied to 25 patients with Parkinson's disease and an equal number of healthy matched control subjects. Most reflexes were found considerably more often in the patients than in the control subjects, especially the snout, the glabellar tap, and its variant, the nasopalpebral reflex. Only the mouth open finger spread reflex was present more often in the control subjects. For all reflexes except this last, the scores for amplitude and persistence of the reflexes for the control group never exceeded the scores for the patient group. Reflexes persisted more often in the patients than in the control subjects. Parkinsonism alone can explain a large number of primitive reflexes, irrespective of the severity or duration of the disease. In contrast, the number of reflexes was related more closely to cognitive scales. It is concluded that such reflexes may be helpful in diagnosing Parkinson's disease. In addition, a standardised protocol for eliciting and scoring is essential for the study of these reflexes in parkinsonism and other neuropsychiatric conditions. PMID:8270937

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

    SciTech Connect

    Taylor-mccabe, Kirsten J; Wingo, Robert M; Haarmann, Timothy K

    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.

  7. 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

  8. [?-, ?-Modulation of the Ventral Tegmental Area Fast-Gamma Activity in the Course of Performance of Conditioned Avoidance Reflex in Rat].

    PubMed

    Serkov, A N; Maiorov, V I

    2015-01-01

    The prestimulus expectation period of conditioned avoidance reflex features synchronized ?-rhythm (1-4 Hz) in the medial prefrontal cortex and the ventral tegmental area (VTA), and synchronized ?-rhythm (6-8 Hz) in the above-mentioned structures and the hippocampus. According to "Granger causality" ?- and ?-rhythms flow (are predictors) in the direction from the prefrontal cortex and the hippocampus to the VTA. Performance of conditioned avoidance reflex was marked by ?-rhythm elimination simultaneously with generation of high-frequency (8-11 Hz) synchronized ?-rhythm. ?-rhythm was shifted from the pre- to poststimulus period and prefrontal cortex--VTA ?-synchrony was eliminated in the cases of mistaken reaction withdrawal, Pavlovian fear conditioning scheme, conditioned signal presentation in the safe chamber part. The phase of ?-, ?-rhythm modulates the amplitude of VTA fast (70-160 Hz) ?-activity envelope, VTA/cortex and VTA/hippocampus ?-phase synchronization and phase lag indexes, and frequency of simultaneously recorded VTA neuronal activity. PMID:26281234

  9. [The striatonigral dopaminergic system and its role in adaptive conditioned reflex behavior].

    PubMed

    Suvorov, N F; Iakimovski?, A F; Saul'skaia, N B

    1984-05-01

    Neurochemical and pharmacological techniques helped to study the role of the nigro-strial dophaminergic system in adaptive conditioned behaviour of rats and dogs. The avoidance technique revealed that dophamine content in the rat neostriatum increased in a more complicated task performance, and administration of 3 micrograms of dophamine into the rostral neostriatum accelerated and improved the conditioning. Nonadaptive forms of behaviour were accompanied by a drop of the dophamine level in the neostriatum. Stimulation of the caudate nucleus' dophamine-reactive system in dogs by means of administration of dophamine (60 micrograms) and phenamine led to deterioration of conditioned and unconditioned components of feeding behaviour. The effects of the dophaminomimetics were suppressed by administration of haloperidol (10 micrograms) and naloxon (0.8 micrograms) into the same area of the caudate nucleus which attested a functional interrelationship between the dophamine- and enkephalin-containing systems of the neostriatum in regulation of feeding behaviour. The data obtained and literature references gave ground for discussing the role of the nigro-strial dophaminergic system in the positive modulation of adaptive conditioned behaviour under natural conditions. PMID:6468694

  10. 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…

  11. A computer analysis of EEG-intersignal reactions during the development of motoric alimentary conditioned reflexes in dogs.

    PubMed

    Dumenko, V N; Kozlov, M K

    1993-01-01

    The background electrical activity of the neocortex in the interstimulus periods at the stage of generalization during the development of alimentary motor conditioned reflexes (CR) in dogs was the investigational object. It was characterized by the appearance of brief (0.1-0.3 sec) trains of high frequencies (HF), significantly exceeding the adjacent initial baseline in frequency and amplitude. The relative variance index which we had developed made it possible to distinguish this EEG phenomenon in the initial realizations of the background activity when they were inputted into a digital computer. It was not possible to evaluate the parameters of the HF chains by means of a spectral correlation analysis. Nonstandard techniques of computer analysis directed toward the decomposition of the EEG tracing into a system of oscillations and toward the obtaining of the corresponding amplitude-frequency distributions (maps) were developed by us for the purpose of accomplishing this objective. It was demonstrated that HF trains were localized in these maps in specific, quite compact regions. PMID:8487940

  12. 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.

  13. Reflexives in Veracruz Huastec.

    ERIC Educational Resources Information Center

    Constable, Peter G.

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

  14. 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.

  15. 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…

  16. 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…

  17. 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)

  18. Sneeze reflex: facts and fiction.

    PubMed

    Songu, Murat; Cingi, Cemal

    2009-06-01

    Sneezing is a protective reflex, and is sometimes a sign of various medical conditions. Sneezing has been a remarkable sign throughout the history. In Asia and Europe, superstitions regarding sneezing extend through a wide range of races and countries, and it has an ominous significance. Although sneezing is a protective reflex response, little else is known about it. A sneeze (or sternutation) is expulsion of air from the lungs through the nose and mouth, most commonly caused by the irritation of the nasal mucosa. Sneezing can further be triggered through sudden exposure to bright light, a particularly full stomach and physical stimulants of the trigeminal nerve, as a result of central nervous system pathologies such as epilepsy, posterior inferior cerebellar artery syndrome or as a symptom of psychogenic pathologies. In this first comprehensive review of the sneeze reflex in the English literature, we aim to review the pathophysiology, etiology, diagnosis, treatment and complications of sneezing. PMID:19617285

  19. The menace reflex.

    PubMed

    van Ballegoij, Wouter J C; Koehler, Peter J; Meulen, Bastiaan C Ter

    2015-06-01

    The menace reflex (blink reflex to visual threat) tests visual processing at the bedside in patients who cannot participate in normal visual field testing. We reviewed a collection of recently discovered historical movies showing the experiments of the Dutch physiologist Gysbertus Rademaker (1887-1957), exploring the anatomy of this reflex by making cerebral lesions in dogs. The experiments show not only that the menace reflex is cortically mediated, but also that lesions outside the visual cortex can abolish the reflex. Therefore, although often erroneously used in this way, an absent menace does not always indicate a visual field deficit. PMID:25670870

  20. The human blink reflex

    PubMed Central

    Shahani, Bhagwan

    1970-01-01

    A detailed study of the human blink reflex in the different parts of the orbicularis oculi muscle has been carried out. The first component of the blink reflex has been demonstrated in patients with Friedreich's ataxia, who have selective loss of large sensory fibres resulting in loss of proprioceptive input. It has been established that both components of the blink reflex are cutaneous reflexes which represent a highly organized and purposeful mechanism in man. Afferent fibres for the blink reflex have been identified in the human supraorbital nerve and their conduction velocity has been estimated for the first time in man. It has been demonstrated that both components of the blink reflex are mediated by the same group of afferent fibres. Images PMID:5531899

  1. 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)

  2. 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

  3. Reflexes in Immunity.

    PubMed

    Tracey, Kevin J

    2016-01-28

    Simple reflex circuits provide crucial infrastructure for the neurological control of organ systems - even the immune system. Now, Gabanyi et al. reveal a reflex mechanism in gut activated by the presence of pathogens that forces macrophages into a tissue protective phenotype. PMID:26824649

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

    PubMed Central

    Ghosh, Arko; Haggard, Patrick

    2014-01-01

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

  6. What is a reflex?

    PubMed Central

    Truog, Robert D.

    2015-01-01

    Uncertainty in diagnosing disorders of consciousness, and specifically in determining whether consciousness has been lost or retained, poses challenging scientific and ethical questions. Recent neuroimaging-based tests for consciousness have cast doubt on the reliability of behavioral criteria in assessing states of consciousness and generate new questions about the assumptions used in formulating coherent diagnostic criteria. The reflex, a foundational diagnostic tool, offers unique insight into these disorders; behaviors produced by unconscious patients are thought to be purely reflexive, whereas those produced by conscious patients can be volitional. Further investigation, however, reveals that reflexes cannot be reliably distinguished from conscious behaviors on the basis of any generalizable empirical characteristics. Ambiguity between reflexive and conscious behaviors undermines the capacity of the reflex to distinguish between disorders of consciousness and has implications for how these disorders should be conceptualized in future diagnostic criteria. PMID:26085602

  7. Investigation to predict patellar tendon reflex using motion analysis technique.

    PubMed

    Tham, L K; Osman, N A Abu; Lim, K S; Pingguan-Murphy, B; Abas, W A B Wan; Zain, N Mohd

    2011-05-01

    The investigation of patellar tendon reflex involves development of a reflex hammer holder, kinematic data collection and analysis of patellar reflex responses using motion analysis techniques. The main aim of this research is to explore alternative means of assessing reflexes as a part of routine clinical diagnosis. The motion analysis system was applied to provide quantitative data which is a more objective measure of the patellar tendon reflex. Kinematic data was collected from 28 males and 22 females whilst subjected to a knee jerk test. Further analysis of kinematic data was performed to predict relationships which might affect the patellar tendon reflex. All subjects were seated on a high stool with their legs hanging freely within the capture volume of the motion analysis system. Knee jerk tests were applied to all subjects, on both sides of the leg, by eliciting hypo, hyper, and normal reflexes. An additional reinforcement technique called the Jendrassik manoeuvre was also performed under the same conditions to elicit a normal patellar tendon reflex. The comparison of reflex response between genders showed that female subjects generally had a greater response compared to males. However, the difference in reflex response between the left leg and the right leg was not significant. Tapping strength to elicit a hyper-reflex produced greater knee-jerk compared to the normal clinical tapping strength. All results were in agreement with clinical findings and results found by some early researchers. PMID:21146440

  8. 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 the presence of some highly refractile substance, such as cholesterin or calcium carbonate, in a retinal exudate or other lesion. It is characteristic of the pathological reflexes that they come and go and change their character according to the progress of the pathological condition. The linear reflexes in particular may change from one from to another, and may be finally transformed into surface reflexes of physiological character. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15Fig. 16Fig. 17Fig. 18Fig. 19Fig. 20Fig. 21Fig. 22Fig. 23Fig. 24Fig. 25Fig. 26 PMID:19992307

  9. 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.

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

    PubMed

    Polverino, Mario; Polverino, Francesca; Fasolino, Marco; Andò, Filippo; Alfieri, Antonio; De Blasio, Francesco

    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

  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. Structural cure for reflex syncope?

    PubMed

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

    2016-01-01

    The ROX Coupler is a device that allows creation of a central arteriovenous anastomosis at the iliac level. The device has been shown to improve exercise capacity in patients with chronic obstructive pulmonary disease and is CE marked for the treatment of resistant and uncontrolled hypertension. Reflex syncope is a challenging clinical condition with limited proven therapeutic options. We describe the resolution of symptoms and tilt table response of a patient who underwent insertion of a ROX Coupler to treat hypertension, and also incidentally had pre-existing vasodepressor syncope. PMID:26791131

  13. Corneomandibular reflex: Anatomical basis

    PubMed Central

    Pistacchi, Michele; Gioulis, Manuela; Mazzon, Davide; Marsala, Sandro Zambito

    2015-01-01

    Corneomandibular reflex is a pathological phenomenon evident in cases of severe brainstem damage. It is considered to be a pathological exteroceptive reflex, associated with precentro bulbar tract lesions. The sign is useful in distinguishing central neurological injuries to metabolic disorders in acutely comatose patients, localizing lesions to the upper brainstem area, determining the depth of coma and its evolution, providing evidence of uncal or transtentorial herniation in acute cerebral hemisphere lesions, and it is a marker of supraspinal level impairment in amyotrophic lateral sclerosis and multiple sclerosis. This sign was evident in a patient with severe brain damage. We discuss the literature findings and its relevance in prognosis establishment. PMID:26752910

  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. Reflex control of immunity.

    PubMed

    Tracey, Kevin J

    2009-06-01

    Inflammation can cause damage and even death. What controls this primitive and potentially lethal innate immune response to injury and infection? Molecular and neurophysiological studies during the past decade have revealed a pivotal answer: immunity is coordinated by neural circuits that operate reflexively. The afferent arc of the reflex consists of nerves that sense injury and infection. This activates efferent neural circuits, including the cholinergic anti-inflammatory pathway, that modulate immune responses and the progression of inflammatory diseases. It might be possible to develop therapeutics that target neural networks for the treatment of inflammatory disorders. PMID:19461672

  16. Reflexivity in Pigeons

    ERIC Educational Resources Information Center

    Sweeney, Mary M.; Urcuioli, Peter J.

    2010-01-01

    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…

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  18. Cutaneous reflexes of the human leg during passive movement

    PubMed Central

    Brooke, John Dennis; McIlroy, William Evans; Staines, William Richard; Angerilli, Peter A; Peritore, Giuseppe F

    1999-01-01

    Four experiments tested the hypothesis that movement-induced discharge of somatosensory receptors attenuates cutaneous reflexes in the human lower limb. In the first experiment, cutaneous reflexes were evoked in the isometrically contracting tibialis anterior muscle (TA) by a train of stimuli to the tibial nerve at the ankle. The constancy of stimulus amplitudes was indirectly verified by monitoring M waves elicited in the abductor hallucis muscle. There was a small increase in the reflex excitation (early latency, EL) during passive cycling movement of the leg compared with when the leg was stationary, a result opposite to that hypothesized. There was no significant effect on the magnitude of the subsequent inhibitory reflex component (middle latency, ML), even with increased rate of movement, or on the latency of any of the reflex components.In the second experiment, the two reflex components (EL and ML) elicited in TA at four positions in the movement cycle were compared with corresponding reflexes elicited with the limb stationary at those positions. Despite the markedly different degree of stretch of the leg muscles, movement phase exerted no statistically significant effect on EL or ML reflex magnitudes.In the third experiment, taps to the quadriceps tendon, to elicit muscle spindle discharge, had no effect on the magnitude of ML in TA muscle. The conditioning attenuated EL magnitude for the first 110 ms. Tendon tap to the skin over the tibia revealed similar attenuation of EL.The sural nerve was stimulated at the ankle in the fourth experiment. TA EMG reflex excitatory and inhibitory responses still showed no significant attenuation with passive movement. Initial somatosensory evoked potentials (SEPs), measured from scalp electrodes, were attenuated by movement.The results indicate that there is separate control of transmission in Ia and cutaneous pathways during leg movement. This suggests that modulation of the cutaneous reflex during locomotion is not the result of inhibition arising from motion-related sensory receptor discharge. PMID:10381606

  19. Binaural interaction of stapedius reflex.

    PubMed

    Iguchi, Y; Ogawa, Y; Tada, Y; Kodama, N

    1996-01-01

    It is known that stapedius reflex (SR) shows bilateral interaction and that its center is located in the brainstem. In the present study, the pattern of SR was compared in two different conditions, either with binaural acoustic stimuli or with monaural stimuli using the impedance measurement method. When the sound source was placed in front of the head model, the amplitude of impedance change was higher in the binaural hearing condition than in the monaural condition, suggesting bilateral superposition. When the sound source was placed laterally to the head model, the amplitude of impedance change was higher in the ipsilateral ear than in the contralateral ear in the binaural condition. In the monaural condition, the amplitude of impedance change in the ipsilateral ear was as high as that obtained in the ipsilateral ear in the binaural condition, whereas it was markedly low in the contralateral ear. It is assumed that sense of sound direction cannot be well maintained without binaural interaction of SR. PMID:8790759

  20. Patterning of somatosympathetic reflexes

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; Yates, B. J.

    1999-01-01

    In a previous study, we reported that vestibular nerve stimulation in the cat elicits a specific pattern of sympathetic nerve activation, such that responses are particularly large in the renal nerve. This patterning of vestibulosympathetic reflexes was the same in anesthetized and decerebrate preparations. In the present study, we report that inputs from skin and muscle also elicit a specific patterning of sympathetic outflow, which is distinct from that produced by vestibular stimulation. Renal, superior mesenteric, and lumbar colonic nerves respond most strongly to forelimb and hindlimb nerve stimulation (approximately 60% of maximal nerve activation), whereas external carotid and hypogastric nerves were least sensitive to these inputs (approximately 20% of maximal nerve activation). In contrast to vestibulosympathetic reflexes, the expression of responses to skin and muscle afferent activation differs in decerebrate and anesthetized animals. In baroreceptor-intact animals, somatosympathetic responses were strongly attenuated (to <20% of control in every nerve) by increasing blood pressure levels to >150 mmHg. These findings demonstrate that different types of somatic inputs elicit specific patterns of sympathetic nerve activation, presumably generated through distinct neural circuits.

  1. Patterning of somatosympathetic reflexes.

    PubMed

    Kerman, I A; Yates, B J

    1999-09-01

    In a previous study, we reported that vestibular nerve stimulation in the cat elicits a specific pattern of sympathetic nerve activation, such that responses are particularly large in the renal nerve. This patterning of vestibulosympathetic reflexes was the same in anesthetized and decerebrate preparations. In the present study, we report that inputs from skin and muscle also elicit a specific patterning of sympathetic outflow, which is distinct from that produced by vestibular stimulation. Renal, superior mesenteric, and lumbar colonic nerves respond most strongly to forelimb and hindlimb nerve stimulation (approximately 60% of maximal nerve activation), whereas external carotid and hypogastric nerves were least sensitive to these inputs (approximately 20% of maximal nerve activation). In contrast to vestibulosympathetic reflexes, the expression of responses to skin and muscle afferent activation differs in decerebrate and anesthetized animals. In baroreceptor-intact animals, somatosympathetic responses were strongly attenuated (to <20% of control in every nerve) by increasing blood pressure levels to >150 mmHg. These findings demonstrate that different types of somatic inputs elicit specific patterns of sympathetic nerve activation, presumably generated through distinct neural circuits. PMID:10484488

  2. Teaching Reflexivity in Qualitative Interviewing

    ERIC Educational Resources Information Center

    Hsiung, Ping-Chun

    2008-01-01

    Reflexivity has gained paramount status in qualitative inquiry. It is central to debates on subjectivity, objectivity, and, ultimately, the scientific foundation of social science knowledge and research. Although much work on doing reflexivity by researchers and practitioners has been published, scholars have only recently begun to explore how one…

  3. Reflex myoclonus in olivopontocerebellar atrophy.

    PubMed Central

    Rodriguez, M E; Artieda, J; Zubieta, J L; Obeso, J A

    1994-01-01

    The presence of reflex myoclonus in response to touching and pin-pricking the wrist or stretching the fingers and to photic stimulation was assessed in 24 patients with a presumed diagnosis of olivopontocerebellar atrophy (OPCA) and in 30 age matched control subjects. Reflex myoclonus to soma-esthetic stimulation was found in 23 patients and in none of the controls. Photic myoclonus was present in 12 patients and in none of the controls. Electrophysiological study of the reflex myoclonus showed enhanced (> 10 microV) somatosensory evoked potentials and an associated reflex electromyographic discharge (C-wave) in 15 patients. These findings indicate that reflex myoclonus is common in OPCA and probably of cortical origin. Images PMID:8158179

  4. [Reflex seizures, cinema and television].

    PubMed

    Olivares-Romero, J

    2015-12-16

    In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot. PMID:26662874

  5. [Reflexes, instincts, emotions and passions].

    PubMed

    Sánchez, Alberto Portera

    2008-01-01

    In animals of the same species, the reflexes, having evolved similarly, in a few milliseconds, automatically activate the corresponding reflex arch and without the intervention of the animal generate the adequate response: medullary, mesencephalic or trans-hemispheric. These neurophysiological functions have allowed the animals to be free from predators and increasy their longevity and, as a consequence, the appearance of numerous species during millions of years. A further step in the reflexes evolution, the instincts emerged and their activity, a result of neuro-hormonal functions, stimulates the male's sexual appetite when the females are receptive for their copulation and fecundation. PMID:18924359

  6. [Characteristics of the functional coupling of cerebral cortical neurons in cats and the signal meaning of the stimulus (the hypothesis of the information switching of conditioned reflex activity)].

    PubMed

    Komissarov, V I

    1988-01-01

    In chronic experiments on cats interrelations were studied between impulse activity of neurones of various auditory cortical zones and associative area under the action of defensive, alimentary or differential acoustic signals. It was found that shifts of the impulse activity of neurones in the studied cortical zones and correlation dependence between them appearing in the given conditions, were of a selective character and were connected with signal meaning of acoustic signals. Neurophysiological mechanisms are discussed of the revealed reorganization of the composition of functional relations of neurones of the cortical representation of the conditioned stimulus analyzer. PMID:3245316

  7. The inhibitory effect of a chewing task on a human jaw reflex.

    PubMed

    Maillou, Pauline; Cadden, Samuel W; Lobbezoo, Frank

    2010-06-01

    This study was undertaken to investigate whether an inhibitory jaw reflex could be modulated by experimentally controlled conditions that mimicked symptoms of temporomandibular disorders. Reflecting on previous work, we anticipated that these conditions might suppress the reflex. Electromyographic recordings were made from a masseter muscle in 18 subjects, while electrical stimuli were applied to the upper lip. An inhibitory reflex wave (mean latency 47 ms) was identified and quantified. Immediately following an accelerated chewing task, which in most cases produced muscle fatigue and/or pain, the size of the reflex wave decreased significantly by about 30%. The suppression of inhibitory jaw reflexes by fatigue and pain may result in positive feedback, which may contribute to the symptoms of temporomandibular disorders. Future studies of temporomandibular disorder sufferers will help to determine whether such reflex changes reflect the underlying etiology and/or are a result of the temporomandibular disorder itself. PMID:20151465

  8. [Phenomenological model of changes in evoked potentials of the sensomotor area of the large cerebral hemispheres during processing of conditioned reflexes].

    PubMed

    Chuprun, B E; Serdiuchenko, V M

    1999-01-01

    A phemenological model of variations in evoked potentials during conditioning is proposed. The model consists of four linear differentional equations. Variations in a wide range of only one parameter of the system of differential equations correspond to all variations in evoked potentials. A variation of this parameter in the presence of constant disturbances at the system input gives rise to the appearance of a constant or increasing signal at the output of the system, which is characteristic for the expectancy wave. PMID:10544829

  9. Reflex Principles of Immunological Homeostasis

    PubMed Central

    Andersson, Ulf; Tracey, Kevin J.

    2015-01-01

    The reasoning that neural reflexes maintain homeostasis in other body organs, and that the immune system is innervated, prompted a search for neural circuits that regulate innate and adaptive immunity. This elucidated the inflammatory reflex, a prototypical reflex circuit that maintains immunological homeostasis. Molecular products of infection or injury activate sensory neurons traveling to the brainstem in the vagus nerve. The arrival of these incoming signals generates action potentials that travel from the brainstem to the spleen and other organs. This culminates in T cell release of acetylcholine, which interacts with ?7 nicotinic acetylcholine receptors (?7 nAChR) on immunocompetent cells to inhibit cytokine release in macrophages. Herein is reviewed the neurophysiological basis of reflexes that provide stability to the immune system, the neural- and receptor-dependent mechanisms, and the potential opportunities for developing novel therapeutic devices and drugs that target neural pathways to treat inflammatory diseases. PMID:22224768

  10. The plantar cushion reflex circuit: an oligosynaptic cutaneous reflex

    PubMed Central

    Egger, M. David; Wall, Patrick D.

    1971-01-01

    1. Reflex toe extension elicited by pressure on the plantar cushion (PC) was studied in cats anaesthetized with Dial. Receptive fields and adequate stimuli for the reflex were evaluated. It was concluded that the receptors for the reflex were chiefly cutaneous pressure receptors in PC. 2. The fastest impulses from the PC receptors for this reflex are conducted to the spinal cord at about 64 m/sec via fibres about 10-11 ?m in diameter, i.e. the largest afferent fibres from PC. The motoneurones active in the reflex mainly supplied the intrinsic plantar muscles. Most active axons ran in the S1 ventral root. 3. Extracellular recordings of interneurones in the dorsal horn of L7 spinal segment revealed that many units at the medial edge of the dorsal horn, chiefly in Rexed's laminae IV and V, were activated by stimuli similar to those eliciting the PC—toe extension reflex. These were termed intermediate threshold PC units. Some of these medially located units were activated monosynaptically by PC stimulation. Intermediate threshold PC units activated disynaptically or polysynaptically were also found in this medial region of the dorsal horn, as well as ventrolaterally and caudally in lamina V. 4. No intermediate threshold PC units sent axons into dorsolateral ipsilateral thoracic white matter, in contrast to lower threshold PC units, 42% of which were driven by lateral column stimulation. 5. Extracellular and intracellular recordings were made from motoneurones activated by adequate stimuli for the reflex. Minimum latencies of EPSPs revealed that, for the fastest component of the reflex, at most two interneurones could be interposed between a primary sensory neurone and a motoneurone. 6. Although convergence of low threshold PC units on to intermediate threshold PC units or on to motoneurones may play a part in the PC—toe extension reflex, it appears probable that the two populations of intermediate threshold PC interneurones described above, that is, the monosynaptic and the disynaptic (with higher order interneurones), mediate the reflex. PMID:5559630

  11. 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.

  12. 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

  13. Reliability of the Achilles tendon tap reflex evoked during stance using a pendulum hammer.

    PubMed

    Mildren, Robyn L; Zaback, Martin; Adkin, Allan L; Frank, James S; Bent, Leah R

    2016-01-01

    The tendon tap reflex (T-reflex) is often evoked in relaxed muscles to assess spinal reflex circuitry. Factors contributing to reflex excitability are modulated to accommodate specific postural demands. Thus, there is a need to be able to assess this reflex in a state where spinal reflex circuitry is engaged in maintaining posture. The aim of this study was to determine whether a pendulum hammer could provide controlled stimuli to the Achilles tendon and evoke reliable muscle responses during normal stance. A second aim was to establish appropriate stimulus parameters for experimental use. Fifteen healthy young adults stood on a forceplate while taps were applied to the Achilles tendon under conditions in which postural sway was constrained (by providing centre of pressure feedback) or unconstrained (no feedback) from an invariant release angle (50°). Twelve participants repeated this testing approximately six months later. Within one experimental session, tap force and T-reflex amplitude were found to be reliable regardless of whether postural sway was constrained (tap force ICC=0.982; T-reflex ICC=0.979) or unconstrained (tap force ICC=0.968; T-reflex ICC=0.964). T-reflex amplitude was also reliable between experimental sessions (constrained ICC=0.894; unconstrained ICC=0.890). When a T-reflex recruitment curve was constructed, optimal mid-range responses were observed using a 50° release angle. These results demonstrate that reliable Achilles T-reflexes can be evoked in standing participants without the need to constrain posture. The pendulum hammer provides a simple method to allow researchers and clinicians to gather information about reflex circuitry in a state where it is involved in postural control. PMID:26454702

  14. 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

  15. 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

  16. Tonic vibration reflexes and background force level

    NASA Technical Reports Server (NTRS)

    Lackner, James R.; Dizio, Paul; Fisk, John

    1992-01-01

    On earth, the functional stretch reflex is an important component in the maintenance of posture and muscle tone. In parabolic flight experiments, it is evaluated whether the functional stretch reflex, as reflected in the tonic vibration reflex, adjusts appropriately for changes in background gravitoinertial force level. Virtually immediate alterations of appropriate sign occurred.

  17. Variable Patterned Pudendal Nerve Stimuli Improves Reflex Bladder Activation

    PubMed Central

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

    2010-01-01

    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 (0.5–100 Hz) was performed under isovolumetric conditions at bladder volumes up to the occurrence of distension evoked reflex contractions. Stimulus evoked reflex bladder contractions were elicited in eight cats. Across all experiments, bursting of 2–10 pulses at 100–200 Hz repeated at continuous stimulation frequencies evoked significantly larger bladder responses than continuous (single pulse) stimulation (52.0 ± 44.5%). Bladder excitation was also effective at 1 Hz continuous stimuli, which is lower than typically reported. Variable patterned pulse bursting resulted in greater evoked reflex bladder pressures and increased the potential stimulation parameter space for effective bladder excitation. Improved bladder excitation should increase the efficacy of neuroprostheses for bladder control. PMID:18403282

  18. 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.

  19. Measurement of patellar and ankle tendon reflexes in normal subjects.

    PubMed

    Struys, M A; Jonkman, E J; Strijers, R L

    1997-01-01

    In order to acquire normal values, patellar and ankle tendon reflexes were measured bilateral in 51 healthy subjects. The reflexes were mechanically evoked with a hand-held hammer which was connected to the trigger input of a two-channel EMG system. For each reflex simultaneous registration took place from surface electrodes on two different locations. The dependence of the latency on body length and age is described as well as the left-right difference and the intra-individual variability. Using similar measurement conditions significantly longer latencies were found than those published earlier. The importance of well defined placement of the electrodes when comparing acquired latencies with normal values is shown. PMID:9063657

  20. 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

  1. No evidence hip joint angle modulates intrinsically produced stretch reflex in human hopping.

    PubMed

    Gibson, W; Campbell, A; Allison, G

    2013-09-01

    Motor output in activities such as walking and hopping is suggested to be mediated neurally by purported stretch reflex augmentation of muscle output. Reflex EMG activity during these tasks has been frequently investigated in the soleus muscle; with alterations in reflex amplitude being associated with changes in hip joint angle/phase of the gait cycle. Previous work has focussed on reflex activity induced by an artificial perturbation or by induction of H-reflexes. As such, it is currently unknown if stretch reflex activity induced intrinsically (as part of the task) is modulated by changes in hip joint angle. This study investigated whether hip joint angle modulated reflex EMG 'burst' activity during a hopping task performed on a custom-built partially reclined sleigh. Ten subjects participated; EMG and kinematic data (VICON motor capture system) was collected for each hop cycle. Participants completed 5 sets of 30s of self-paced hopping in (1) hip neutral and (2) hip 60° flexion conditions. There was no difference in EMG 'burst' activity or in sagittal plane kinematics (knee/ankle) in the hopping task between the two conditions. The results indicate that during a functional task such as hopping, changes in hip angle do not alter the stretch reflex-like activity associated with landing. PMID:23791780

  2. Reversible grasp reflexes in normal pressure hydrocephalus.

    PubMed

    Thomas, Rhys H; Bennetto, Luke; Silva, Mark T

    2009-05-01

    We present two cases of normal pressure hydrocephalus in combination with grasp reflexes. In both cases the grasp reflexes disappeared following high volume cerebrospinal fluid removal. In one of the cases the grasp reflexes returned over a period of weeks but again resolved following definitive cerebrospinal fluid shunting surgery, and remained absent until final follow up at 9 months. We hypothesise that resolving grasp reflexes following high volume CSF removal has both diagnostic and prognostic value in normal pressure hydrocephalus, encouraging larger studies on the relevance of primitive reflexes in NPH. PMID:19117665

  3. Nonlinear identification of stretch reflex dynamics.

    PubMed

    Kearney, R E; Hunter, I W

    1988-01-01

    The objective of this study was to use nonlinear identification techniques to study the dynamics of stretch reflexes in the human calf muscles (gastrocnemius-soleus). Stochastic perturbations of ankle position were applied while subjects maintained a constant, tonic contraction of gastrocnemius-soleus. Linear models of the relation between ankle velocity and the electromyographic (EMG) activity under these conditions typically accounted for less than 40% of the observed EMG variance. Nonlinear system identification techniques were then applied. The first- and second-order Wiener kernels were computed as the initial stage of this analysis. These did not provide an adequate description of system behavior; subsequent simulation studies showed that the major problem with the Wiener analysis was that the input spectrum was not adequately white. Nevertheless, the shape of the second-order Wiener kernel suggested that a Hammerstein structure consisting of a static nonlinearity followed by a dynamic linear system would be appropriate. Consequently, we used an iterative procedure for Hammerstein system identification to determine the form of the static nonlinearity and the associated linear dynamics. The resulting nonlinear model provided a much better description of the system's behavior than did the linear models (variance accounted for greater than 60%). Furthermore, they confirmed our previous empirical findings; the static nonlinearity closely resembled a half-wave rectifier while the dynamics were typified by a pure delay and a velocity filter. The application of nonlinear identification techniques thus produced a much improved, physically meaningful model of stretch reflex behavior. PMID:3408053

  4. Vestibulocollic reflexes in the absence of head postural control

    PubMed Central

    Forbes, Patrick A.; Siegmund, Gunter P.; Happee, Riender; Schouten, Alfred C.

    2014-01-01

    Percutaneous electrical vestibular stimulation evokes reflexive responses in appendicular muscles that are suppressed during tasks in which the muscles are not contributing to balance control. In neck muscles, which stabilize the head on the torso and in space, it is unclear whether similar postural task dependence shapes vestibular reflexes. We investigated whether vestibulocollic reflexes are modulated during tasks in which vestibular information is not directly relevant to maintaining the head balanced on the torso. We hypothesized that vestibulocollic reflexes would be 1) evoked when neck muscles are not involved in balancing the head on the torso and 2) invariant across synergistic neck muscle contraction tasks. Muscle activity was recorded bilaterally in sternocleidomastoid and splenius capitis muscles during head-free and head-fixed conditions while subjects were exposed to stochastic electrical vestibular stimulation (±5 mA, 0–75 Hz). Significant vestibular reflex responses (P < 0.05) were observed during head-free and head-fixed trials. Response magnitude and timing were similar between head-free and head-fixed trials for sternocleidomastoid, but splenius capitis magnitudes decreased with the head fixed by ?25% (P < 0.05). Nevertheless, this indicates that vestibulocollic responses are evoked independent of the requirement to maintain postural control of the head on the torso. Response magnitude and timing were similar across focal muscle contractions (i.e., axial rotation/flexion/extension) provided the muscle was active. In contrast, when subjects cocontracted neck muscles, vestibular-evoked responses decreased in sternocleidomastoid by ?30–45% (P < 0.05) compared with focal muscle contractions but remained unchanged in splenius capitis. These results indicate robust vestibulocollic reflex coupling, which we suggest functions through its closed-loop influence on head posture to ensure cervical spine stabilization. PMID:25008409

  5. 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.

  6. Excitability of the soleus H reflex during graded walking in humans.

    PubMed

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

    1995-01-01

    The excitability of the soleus Hoffmann (H) reflex was measured in five healthy male subjects during graded treadmill walking. Uphill and downhill walking at an 8% grade as well as level walking were used to vary the demands for lengthening and shortening contractions of the soleus muscle. These changes were assumed to cause differences in control of the afferent input in the spinal cord and the voluntary output to the soleus muscle. The H reflex was strongly modulated in all three walking conditions, high during the stance phase and low or absent during the swing phase. The shape of the modulations was, however, different. At uphill walking the reflex increased gradually during the whole stance phase and seemed to follow the soleus electromyogram (EMG) pattern closely. In the downhill condition the reflex excitability increased rapidly at heel strike like the soleus EMG and co-contraction of the anterior tibial muscle was observed. At level walking a fast rise in reflex excitability was seen just after heel strike with low or absent soleus EMG. Mean soleus EMG was lower during downhill than during uphill or level walking, but the mean H reflex amplitude was similar in all three conditions. However, when the H reflex was related directly to the EMG activity by linear regression the reflex gain was lower during uphill walking than in the two other conditions. Furthermore, the ratio between H reflex and EMG amplitude was high during the first half of the stance phase at level walking indicating an elevated reflex excitability independent of the voluntary motor output. It is therefore concluded that the modulation of reflexes during walking cannot be interpreted in terms of the idea of automatic gain compensation. The reflexes must be controlled specifically and independently during the different phases of the motor output to meet the mechanical requirements of the movement task. Most explicitly this was seen during downhill walking, where an elevated reflex excitability together with co-contraction at the ankle joint seem to provide increased joint stiffness and security, when the kinetic energy of the body has to be brought under control at heel strike. PMID:7625165

  7. Authentic role of ATP signaling in micturition reflex.

    PubMed

    Takezawa, Kentaro; Kondo, Makoto; Kiuchi, Hiroshi; Ueda, Norichika; Soda, Tetsuji; Fukuhara, Shinichiro; Takao, Tetsuya; Miyagawa, Yasushi; Tsujimura, Akira; Matsumoto-Miyai, Kazumasa; Ishida, Yusuke; Negoro, Hiromitsu; Ogawa, Osamu; Nonomura, Norio; Shimada, Shoichi

    2016-01-01

    Adenosine triphosphate (ATP) is a signaling molecule that regulates cellular processes. Based on previous studies of bladder function over the past decade, bladder ATP signaling was thought to have an essential role in the normal micturition reflex. In this study, we performed detailed analyses of bladder function in purinergic receptor-deficient mice using the automated voided stain on paper method and video-urodynamics. Unexpectedly, a lack of P2X2 or P2X3 receptors did not affect bladder function under normal physiological conditions, indicating that bladder ATP signaling is not essential for normal micturition reflex. In contrast, we found that lipopolysaccharide (LPS) induced markedly high levels of ATP release from the urothelium. In addition, LPS-induced rapid bladder hyperactivity was attenuated in P2X2(-/-) and P2X3(-/-) mice. Contrary to the previous interpretation, our present findings indicate that bladder ATP signaling has a fundamental role in the micturition reflex, especially in bladder dysfunction, under pathological conditions. Therefore, the bladder ATP signaling pathway might be a highly promising therapeutic target for functional bladder disorders. This study newly defines an authentic role for bladder ATP signaling in the micturition reflex. PMID:26795755

  8. Authentic role of ATP signaling in micturition reflex

    PubMed Central

    Takezawa, Kentaro; Kondo, Makoto; Kiuchi, Hiroshi; Ueda, Norichika; Soda, Tetsuji; Fukuhara, Shinichiro; Takao, Tetsuya; Miyagawa, Yasushi; Tsujimura, Akira; Matsumoto-Miyai, Kazumasa; Ishida, Yusuke; Negoro, Hiromitsu; Ogawa, Osamu; Nonomura, Norio; Shimada, Shoichi

    2016-01-01

    Adenosine triphosphate (ATP) is a signaling molecule that regulates cellular processes. Based on previous studies of bladder function over the past decade, bladder ATP signaling was thought to have an essential role in the normal micturition reflex. In this study, we performed detailed analyses of bladder function in purinergic receptor-deficient mice using the automated voided stain on paper method and video-urodynamics. Unexpectedly, a lack of P2X2 or P2X3 receptors did not affect bladder function under normal physiological conditions, indicating that bladder ATP signaling is not essential for normal micturition reflex. In contrast, we found that lipopolysaccharide (LPS) induced markedly high levels of ATP release from the urothelium. In addition, LPS-induced rapid bladder hyperactivity was attenuated in P2X2−/− and P2X3−/− mice. Contrary to the previous interpretation, our present findings indicate that bladder ATP signaling has a fundamental role in the micturition reflex, especially in bladder dysfunction, under pathological conditions. Therefore, the bladder ATP signaling pathway might be a highly promising therapeutic target for functional bladder disorders. This study newly defines an authentic role for bladder ATP signaling in the micturition reflex. PMID:26795755

  9. Gastric sensitivity and reflexes: basic mechanisms underlying clinical problems.

    PubMed

    Azpiroz, Fernando; Feinle-Bisset, Christine; Grundy, David; Tack, Jan

    2014-02-01

    Both reflex and sensory mechanisms control the function of the stomach, and disturbances in these mechanisms may explain the pathophysiology of disorders of gastric function. The objective of this report is to perform a literature-based critical analysis of new, relevant or conflicting information on gastric sensitivity and reflexes, with particular emphasis on the comprehensive integration of basic and clinical research data. The stomach exerts both phasic and tonic muscular (contractile and relaxatory) activity. Gastric tone determines the capacity of the stomach and mediates both gastric accommodation to a meal as well as gastric emptying, by partial relaxation or progressive recontraction, respectively. Perception and reflex afferent pathways from the stomach are activated independently by specific stimuli, suggesting that the terminal nerve endings operate as specialized receptors. Particularly, perception appears to be related to stimulation of tension receptors, while the existence of volume receptors in the stomach is uncertain. Reliable techniques have been developed to measure gastric perception and reflexes both in experimental and clinical conditions, and have facilitated the identification of abnormal responses in patients with gastric disorders. Gastroparesis is characterised by impaired gastric tone and contractility, whereas patients with functional dyspepsia have impaired accommodation, associated with antral distention and increased gastric sensitivity. An integrated view of fragmented knowledge allows the design of pathophysiological models in an attempt to explain disorders of gastric function, and may facilitate the development of mechanistically orientated treatments. PMID:24306100

  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. Conscious thoughts from reflex-like processes: a new experimental paradigm for consciousness research.

    PubMed

    Allen, Allison K; Wilkins, Kevin; Gazzaley, Adam; Morsella, Ezequiel

    2013-12-01

    The contents of our conscious mind can seem unpredictable, whimsical, and free from external control. When instructed to attend to a stimulus in a work setting, for example, one might find oneself thinking about household chores. Conscious content thus appears different in nature from reflex action. Under the appropriate conditions, reflexes occur predictably, reliably, and via external control. Despite these intuitions, theorists have proposed that, under certain conditions, conscious content resembles reflexes and arises reliably via external control. We introduce the Reflexive Imagery Task, a paradigm in which, as a function of external control, conscious content is triggered reliably and unintentionally: When instructed to not subvocalize the name of a stimulus object, participants reliably failed to suppress the set-related imagery. This stimulus-elicited content is considered 'high-level' content and, in terms of stages of processing, occurs late in the processing stream. We discuss the implications of this paradigm for consciousness research. PMID:24056177

  12. Reflex transmission to lumbar ?-motoneurones in the mouse similar and different to those in the cat.

    PubMed

    Schomburg, Eike D; Kalezic, Ivana; Dibaj, Payam; Steffens, Heinz

    2013-07-01

    Investigation and interpretation of defective motor circuitries in transgenic mice required further basic results from wild-type mice. Therefore, we investigated the lumbar motor reflex pattern in anaesthetised mice using intracellular motoneuronal recording and monosynaptic reflex testing. Thresholds and latencies in mice were similar to those in cats: thresholds for monosynaptic (group I) EPSPs were slightly above 1T (T=threshold for the lowest threshold fibres), around 1.5T for group II EPSPs and above 10T for group III EPSPs; group I EPSPs were maximal with a stimulus strength around 2T, group II EPSPs were maximal with 5-8T; latencies to the group I incoming volley were below 1ms for monosynaptic group I EPSPs, around 3ms for polysynaptic group II EPSPs and above 4ms for polysynaptic group III EPSPs. In contrast to reflex actions in the cat, monosynaptic gastrocnemius-soleus reflexes were facilitated by conditioning stimulation of the peroneal, sural and tibial nerves, i.e. by a variety of different, probably flexor reflex afferents. This facilitation persisted after high lumbar spinalisation indicating an independency to supraspinal influences. Nociceptive muscle afferents facilitated the peroneal monosynaptic reflex while nociceptive cutaneous afferents from the foot sole inhibited the ipsilateral but facilitated the contralateral peroneal reflex. PMID:23562791

  13. Diachronic Processes in the Evolution of Reflexives.

    ERIC Educational Resources Information Center

    Kemmer, Suzanne

    An analysis of the evolution of reflexive verbs focuses on reflexive to middle voice development in two-form middle systems, which include Russian, Old Norse, Turkish, and Hungarian. The diachronic processes associated with these systems are examined. The changes in the languages over time represent a gradual change in the semantics of the…

  14. [Non-reflex activity of the CNS].

    PubMed

    Brozek, G

    1995-06-01

    Recent studies of biological rhythms have modified Sherrington's concept of nervous system as exclusively reflexive to include the fact that some neural activity is also endogenously rhythmic. Reflexes are undoubtedly the most important components of animal's and human behavior. But are reflexes the basic units of all complex movements and acts? Rhythmical movements such as respiration, walking and running and other forms of locomotion, as well as rhythmical alimentary processes such as respiration, walking and running and other forms of locomotion, as well as rhythmical alimentary processes such as licking, mastication, and the peristaltic propulsion of nutrients and waste are examples of acts controlled by intrinsic oscillators, so called central pattern generators. Information from the periphery is, however, essential for controlling the extent and rate of movements. Between reflex and non-reflex activity it is possible to place complex species-specific responses called by ethologists fixed-action patterns. Recent investigators have shown that many complex sequences of behavior like speech or piano playing are determined by an internal plan, rather than being generated by a "chain" of reflexes. Non-reflexive activity appears earlier in ontogeny, and is probably phylogenetically older than reflexes. PMID:8665596

  15. Reflexivity: Towards a Theory of Lifelong Learning.

    ERIC Educational Resources Information Center

    Edwards, Richard; Ranson, Stewart; Strain, Michael

    2002-01-01

    The current notion of lifelong learning in policy and practice is dominated by behaviorist, adaptive accumulation of skills and qualifications. An alternative is reflexive lifelong learning, developed through social learning networks within the context of dislocation and uncertainty. It involves the reflexive practices of metacognitive analysis…

  16. The grasp and other primitive reflexes.

    PubMed

    Schott, J M; Rossor, M N

    2003-05-01

    Primitive reflexes are typically present in childhood, suppressed during normal development, and may reappear with diseases of the brain, particularly those affecting the frontal lobes. In this review we discuss some historical aspects surrounding these reflexes, how they might be elicited and interpreted, and their potential clinical utility in modern neurological practice. PMID:12700289

  17. Whole-body vibration-induced muscular reflex: Is it a stretch-induced reflex?

    PubMed Central

    Cakar, Halil Ibrahim; Cidem, Muharrem; Sebik, Oguz; Yilmaz, Gizem; Karamehmetoglu, Safak Sahir; Kara, Sadik; Karacan, Ilhan; Türker, Kemal S?tk?

    2015-01-01

    [Purpose] Whole-body vibration (WBV) can induce reflex responses in muscles. A number of studies have reported that the physiological mechanisms underlying this type of reflex activity can be explained by reference to a stretch-induced reflex. Thus, the primary objective of this study was to test whether the WBV-induced muscular reflex (WBV-IMR) can be explained as a stretch-induced reflex. [Subjects and Methods] The present study assessed 20 healthy males using surface electrodes placed on their right soleus muscle. The latency of the tendon reflex (T-reflex) as a stretch-induced reflex was compared with the reflex latency of the WBV-IMR. In addition, simulations were performed at 25, 30, 35, 40, 45, and 50?Hz to determine the stretch frequency of the muscle during WBV. [Results] WBV-IMR latency (40.5 ± 0.8?ms; 95% confidence interval [CI]: 39.0–41.9?ms) was significantly longer than T-reflex latency (34.6 ± 0.5?ms; 95% CI: 33.6–35.5?ms) and the mean difference was 6.2?ms (95% CI of the difference: 4.7–7.7?ms). The simulations performed in the present study demonstrated that the frequency of the stretch signal would be twice the frequency of the vibration. [Conclusion] These findings do not support the notion that WBV-IMR can be explained by reference to a stretch-induced reflex. PMID:26310784

  18. Sudomotor function in sympathetic reflex dystrophy.

    PubMed

    Birklein, F; Sittl, R; Spitzer, A; Claus, D; Neundörfer, B; Handwerker, H O

    1997-01-01

    Sudomotor functions were studied in 27 patients suffering from reflex sympathetic dystrophy (RSD) according to the criteria established by Bonica (18 women, 9 men; mean age 50 +/- 12.3 years; median duration of disease 8 weeks, range 2-468 weeks). To measure local sweating rates, two small chambers (5 cm2) were affixed to corresponding areas of hairy skin on the affected and unaffected limbs. Dry nitrogen gas was passed through the chambers (270 ml/min) and evaporation was recorded at both devices with hygrometers. Thermoregulatory sweating (TST) was induced by raising body temperature (intake of 0.5 1 hot tea and infra-red irradiation). Local sweating was also induced through an axon reflex (QSART) by transcutaneous iontophoretic application of carbachol (5 min, 1 mA). In addition, skin temperature was measured on the affected and unaffected side by infra-red thermography. Mean skin temperature was significantly higher on the affected side (P < 0.003). In spite of the temperature differences, there was no difference in basal sweating on the affected and unaffected side. However, both methods of sudomotor stimulation lead to significantly greater sweating responses on the affected compared to the unaffected side (TST: P < 0.05, QSART: P < 0.004). Latency to onset of sweating was significantly shorter on the affected side under both test conditions (P < 0.04 and P < 0.003, respectively). Sweat responses were not correlated to absolute skin temperature but were probably related to the increased blood flow on the affected side. Our findings imply a differential disturbance of vasomotor and sudomotor mechanisms in affected skin. Whereas vasoconstrictor activity is apparently lowered, sudomotor output is either unaltered or may even be enhanced. PMID:9060012

  19. The medial olivocochlear reflex in children during active listening

    PubMed Central

    Smith, Spencer B.; Cone, Barbara

    2015-01-01

    Objective To determine if active listening modulates the strength of the medial olivocochlear (MOC) reflex in children. Design Click-evoked otoacoustic emissions (CEOAEs) were recorded from the right ear in quiet and in four test conditions: one with contralateral broadband noise (BBN) only, and three with active listening tasks wherein attention was directed to speech embedded in contralateral BBN. Study sample Fifteen typically-developing children (ranging in age from 8 to 14 years) with normal hearing. Results CEOAE levels were reduced in every condition with contralateral acoustic stimulus (CAS) when compared to preceding quiet conditions. There was an additional systematic decrease in CEOAE level with increased listening task difficulty, although this effect was very small. These CEOAE level differences were most apparent in the 8–18 ms region after click onset. Conclusions Active listening may change the strength of the MOC reflex in children, although the effects reported here are very subtle. Further studies are needed to verify that task difficulty modulates the activity of the MOC reflex in children. PMID:25735203

  20. 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

  1. 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.

  2. Cutaneous reflex modulation and self-induced reflex attenuation in cerebellar patients

    PubMed Central

    Van Calenbergh, Frank; Swinnen, Stephan P.; Duysens, Jacques

    2014-01-01

    Modulation of cutaneous reflexes is important in the neural control of walking, yet knowledge about underlying neural pathways is still incomplete. Recent studies have suggested that the cerebellum is involved. Here we evaluated the possible roles of the cerebellum in cutaneous reflex modulation and in attenuation of self-induced reflexes. First we checked whether leg muscle activity during walking was similar in patients with focal cerebellar lesions and in healthy control subjects. We then recorded cutaneous reflex activity in leg muscles during walking. Additionally, we compared reflexes after standard (computer triggered) stimuli with reflexes after self-induced stimuli for both groups. Biceps femoris and gastrocnemius medialis muscle activity was increased in the patient group compared with the control subjects, suggesting a coactivation strategy to reduce instability of gait. Cutaneous reflex modulation was similar between healthy control subjects and cerebellar patients, but the latter appeared less able to attenuate reflexes to self-induced stimuli. This suggests that the cerebellum is not primarily involved in cutaneous reflex modulation but that it could act in attenuation of self-induced reflex responses. The latter role in locomotion would be consistent with the common view that the cerebellum predicts sensory consequences of movement. PMID:25392164

  3. Excitability changes of somatic and viscero-somatic nociceptive reflexes in the decerebrate-spinal rabbit: role of NMDA receptors.

    PubMed Central

    Laird, J M; de la Rubia, P G; Cervero, F

    1995-01-01

    1. Wind-up (frequency-dependent potentiation of the responses of spinal neurones to stimulation of unmyelinated afferents) and other N-methyl-D-aspartate (NMDA) receptor-mediated phenomena have been proposed as key mechanisms underlying persistent pain states. In this study we have compared wind-up in visceral and somatic nociceptive pathways to examine the possible contribution of these mechanisms to visceral pain and hyperalgesia. 2. Experiments were performed on thirteen decerebrate spinalized rabbits. A somato-somatic (SS) reflex (evoked by stimulating skin and muscle afferents from the L2 spinal nerve) and a viscero-somatic (VS) reflex (evoked by stimulating visceral afferents in the splanchnic nerve) were recorded from the L1 spinal nerve. The reflexes consisted of an early (A fibre) and a late (C fibre) component. 3. Conditioning trains of sixteen high intensity electrical stimuli at 1 Hz were applied to the somatic or visceral nerve. These conditioning stimuli did not produce wind-up in the early component of either reflex but evoked powerful wind-up in the late SS reflex (mean percentage of baseline +/- S.E.M., 191 +/- 30%). In contrast wind-up was weak or absent in the late VS reflex (mean percentage of baseline +/- S.E.M., 21 +/- 6%). Conditioning of somatic afferents facilitated both the early and late SS reflex but strongly depressed the early and late VS reflex. Conditioning of visceral afferents had little effect on the early SS reflex, but depressed the early VS reflex and the late components of both reflexes. 4. Intravenous administration (1-10 mg kg-1) of the NMDA receptor antagonist ketamine dose-dependently inhibited the strong wind-up in the late SS reflex and the weak wind-up in the late VS reflex, but also dose-dependently inhibited the early and late components of both baseline reflexes. 5. We conclude that neural mechanisms other than wind-up may underlie the development of visceral pain and hyperalgesia. The present results emphasize the important differences in the processing of somatic and visceral nociceptive input by spinal nociceptive systems and confirm the involvement of NMDA receptors in the spinal processing of nociceptive information. PMID:8847646

  4. [Research progress of rectoanal inhibitory reflex].

    PubMed

    Yin, Shuhui; Zhao, Ke

    2015-12-25

    The understanding of rectoanal inhibitory reflex (RAIR) is progressing for the latest 100 years. From the discovery of its important role in diagnosis of Hirschsprung's disease to all aspects of its development, reflex pathways, neural regulation and physiological functions, there have been more in-depth explorations. It is now recognized that a number of other diseases also have a more specific performance of RAIR. It has become an important and indispensable part to anorectal manometry. Research progress of rectoanal inhibitory reflex is reviewed in this article. PMID:26704013

  5. Changes in the Achilles tendon reflexes following Skylab missions

    NASA Technical Reports Server (NTRS)

    Baker, J. T.; Nicogossian, A. E.; Hoffler, G. W.; Johnson, R. L.; Hordinsky, J. R.

    1977-01-01

    Postflight measurements of Achilles tendon reflex duration on Skylab crewmen indicate a state of disequilibrium between the flexor and extensor muscle groups with an initial decrease in reflex duration. As the muscles regain strength and mass there occurs an overcompensation reflected by increased reflex duration. Finally, when a normal neuromuscular state is reached the reflex duration returns to baseline value.

  6. 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…

  7. Effect of naloxone on tooth pulp-evoked jaw-opening reflex in the barbiturate-anaesthetized cat.

    PubMed

    Huopaniemi, T; Pertovaara, A; Jyväsjärvi, E; Carlson, S

    1988-11-01

    The threshold of the tooth pulp-evoked jaw-opening reflex was uninfluenced by administration of 0.5 or 5.0 mg kg-1, i.v. naloxone, a specific opioid antagonist, in the barbiturate-anaesthetized cat. Furthermore, facilitatory or inhibitory interactions between two successive tooth pulp-evoked jaw reflex responses were not influenced by naloxone. It is concluded that naloxone-sensitive opioid receptor-mediated mechanisms do not contribute to the modulation of tooth pulp-evoked reflexes by conditioning dental stimuli. Also they do not exert a tonic inhibition on the sensory or motor part of the tooth pulp-driven reflexes. Experiments performed for comparison showed that the non-nociceptive polysynaptic reflex discharge in the flexo-motor neurons of the limb was not influenced by naloxone either. PMID:2852448

  8. Primitive reflexes and early motor development.

    PubMed

    Bartlett, D

    1997-06-01

    To investigate the relationship between primitive reflexes and typical early motor development, 156 full-term infants with normal 18-month developmental outcomes were assessed using a modified Primitive Reflex Profile (PRP) and the Alberta Infant Motor Scale (AIMS) at 6 weeks and 3 and 5 months. No significant positive or negative correlations were obtained between the scores of the PRP and the AIMS at any of the ages assessed. Similarly, PRP scores did not differ between infants scoring above and below the 50th percentile on the AIMS. Primitive reflexes were unrelated to motor development. If this finding is maintained among infants at risk for motor disability, observational assessment of spontaneously generated movement, rather than isolated testing of primitive reflexes, might yield more valuable information on the child's overall level of maturation. Intervention for children with identified motor delays or neurological impairments might not need to be focused on either suppression or enhancement of these motor functions. PMID:9213229

  9. Sucking-pads and primitive sucking reflex.

    PubMed

    Hendrik, H D

    2013-01-01

    Sucking pads are hyperkeratotic thickenings of the inner aspect of the vermillion border of the lips of neonates. They develop around the 25th week of gestation and are the result of the primitive sucking reflex which is brain-stem mediated. The presence of sucking pads at birth represents an effective sucking reflex and as such it is recommended as a screening tool that indicates an intact motor neuron function in neonates. PMID:24441083

  10. Neural Mechanisms Influencing Interlimb Coordination during Locomotion in Humans: Presynaptic Modulation of Forearm H-Reflexes during Leg Cycling

    PubMed Central

    Nakajima, Tsuyoshi; Mezzarane, Rinaldo A.; Klarner, Taryn; Barss, Trevor S.; Hundza, Sandra R.; Komiyama, Tomoyoshi; Zehr, E. Paul

    2013-01-01

    Presynaptic inhibition of transmission between Ia afferent terminals and alpha motoneurons (Ia PSI) is a major control mechanism associated with soleus H-reflex modulation during human locomotion. Rhythmic arm cycling suppresses soleus H-reflex amplitude by increasing segmental Ia PSI. There is a reciprocal organization in the human nervous system such that arm cycling modulates H-reflexes in leg muscles and leg cycling modulates H-reflexes in forearm muscles. However, comparatively little is known about mechanisms subserving the effects from leg to arm. Using a conditioning-test (C-T) stimulation paradigm, the purpose of this study was to test the hypothesis that changes in Ia PSI underlie the modulation of H-reflexes in forearm flexor muscles during leg cycling. Subjects performed leg cycling and static activation while H-reflexes were evoked in forearm flexor muscles. H-reflexes were conditioned with either electrical stimuli to the radial nerve (to increase Ia PSI; C-T interval ?=?20 ms) or to the superficial radial (SR) nerve (to reduce Ia PSI; C-T interval ?=?37–47 ms). While stationary, H-reflex amplitudes were significantly suppressed by radial nerve conditioning and facilitated by SR nerve conditioning. Leg cycling suppressed H-reflex amplitudes and the amount of this suppression was increased with radial nerve conditioning. SR conditioning stimulation removed the suppression of H-reflex amplitude resulting from leg cycling. Interestingly, these effects and interactions on H-reflex amplitudes were observed with subthreshold conditioning stimulus intensities (radial n., ?0.6×MT; SR n., ? perceptual threshold) that did not have clear post synaptic effects. That is, did not evoke reflexes in the surface EMG of forearm flexor muscles. We conclude that the interaction between leg cycling and somatosensory conditioning of forearm H-re?ex amplitudes is mediated by modulation of Ia PSI pathways. Overall our results support a conservation of neural control mechanisms between the arms and legs during locomotor behaviors in humans. PMID:24204611

  11. Next generation control system for reflexive aerostructures

    NASA Astrophysics Data System (ADS)

    Maddux, Michael R.; Meents, Elizabeth P.; Barnell, Thomas J.; Cable, Kristin M.; Hemmelgarn, Christopher; Margraf, Thomas W.; Havens, Ernie

    2010-04-01

    Cornerstone Research Group Inc. (CRG) has developed and demonstrated a composite structural solution called reflexive composites for aerospace applications featuring CRG's healable shape memory polymer (SMP) matrix. In reflexive composites, an integrated structural health monitoring (SHM) system autonomously monitors the structural health of composite aerospace structures, while integrated intelligent controls monitor data from the SHM system to characterize damage and initiate healing when damage is detected. Development of next generation intelligent controls for reflexive composites were initiated for the purpose of integrating prognostic health monitoring capabilities into the reflexive composite structural solution. Initial efforts involved data generation through physical inspections and mechanical testing. Compression after impact (CAI) testing was conducted on composite-reinforced shape memory polymer samples to induce damage and investigate the effectiveness of matrix healing on mechanical performance. Non-destructive evaluation (NDE) techniques were employed to observe and characterize material damage. Restoration of mechanical performance was demonstrated through healing, while NDE data showed location and size of damage and verified mitigation of damage post-healing. Data generated was used in the development of next generation reflexive controls software. Data output from the intelligent controls could serve as input to Integrated Vehicle Health Management (IVHM) systems and Integrated Resilient Aircraft Controls (IRAC). Reflexive composite technology has the ability to reduce maintenance required on composite structures through healing, offering potential to significantly extend service life of aerospace vehicles and reduce operating and lifecycle costs.

  12. Trigemino-cervical reflexes in normal subjects.

    PubMed

    Ertekin, C; Celebisoy, N; Uluda?, B

    1996-11-01

    Trigemino-cervical reflexes, recorded from the semispinalis capitis muscle (SCM) in the posterior neck, were studied in 35 healthy volunteers, in response to electrical stimulation of the supraorbital trigeminal nerve and glabellar tapping. Simultaneous responses evoked from the ipsilateral orbicularis oculi muscle (OOM) were also recorded i.e. blink reflexes. Electrical stimulation of the supraorbital nerve elicited a reflex response with a latency of about 50 ms from the ipsilateral SCM which was called C3. An early reflex response, which sometimes had two components with latencies of 18 ms and 35 ms, was elicited with glabellar taps. They were called C1 and C2 respectively. When C1 and C2 were elicited with usual glabellar taps, C3 was suppressed. With electrical stimulation, suppression of C1 and C2 was noted, though C3 could easily be obtained. Electrophysiological characteristics of C1 (and C2) were compatible with an oligosynaptic, innocuous reflex, whereas C3 seemed to be multisynaptic and nociceptive in nature. A negative interaction between these two reflexes was observed. PMID:8981303

  13. Gadolinium attenuates exercise pressor reflex in cats.

    PubMed

    Hayes, S G; Kaufman, M P

    2001-05-01

    The exercise pressor reflex, which arises from the contraction-induced stimulation of group III and IV muscle afferents, is widely believed to be evoked by metabolic stimuli signaling a mismatch between blood/oxygen demand and supply in the working muscles. Nevertheless, mechanical stimuli may also play a role in evoking the exercise pressor reflex. To determine this role, we examined the effect of gadolinium, which blocks mechanosensitive channels, on the exercise pressor reflex in both decerebrate and alpha-chloralose-anesthetized cats. We found that gadolinium (10 mM; 1 ml) injected into the femoral artery significantly attenuated the reflex pressor responses to static contraction of the triceps surae muscles and to stretch of the calcaneal (Achilles) tendon. In contrast, gadolinium had no effect on the reflex pressor response to femoral arterial injection of capsaicin (5 microg). In addition, gadolinium significantly attenuated the responses of group III muscle afferents, many of which are mechanically sensitive, to both static contraction and to tendon stretch. Gadolinium, however, had no effect on the responses of group IV muscle afferents, many of which are metabolically sensitive, to either static contraction or to capsaicin injection. We conclude that mechanical stimuli arising in contracting skeletal muscles contribute to the elicitation of the exercise pressor reflex. PMID:11299217

  14. Recurrent inhibition of the bladder C fibre reflex in the cat and its response to naloxone

    PubMed Central

    Mazières, L; Jiang, C H; Lindström, S

    2006-01-01

    Recurrent inhibition of the bladder C fibre reflex was studied in adult female cats anaesthetized with ?-chloralose. Test reflexes were evoked by electrical stimulation of bladder A? and C afferents in the right pelvic nerve and were recorded from the proximal end of a small ipsilateral pelvic nerve branch, transected close to the bladder. Such test reflexes were consistently depressed by repetitive electrical stimulation of the contralateral bladder pelvic nerve (20 Hz, 20 s) at intensities sufficient to recruit axons of bladder preganglionic neurones. The inhibition could be evoked after transection of the left dorsal roots S1–S4 and the sympathetic supply to the bladder but was abolished by transection of the pelvic nerve central to the site of stimulation. Hence, it most likely involved central recurrent collaterals of antidromically activated bladder preganglionic neurones. The reflex suppression was quite considerable – maximal C fibre reflexes were reduced to a group mean of 25% (± 9% confidence interval) of their control size. The effect had a slow onset, requiring a few seconds of conditioning stimulation to be revealed, and was very long lasting (minutes). Naloxone (0.01–0.5 mg kg?1i.v.) abolished the recurrent inhibition of both the C fibre and A? bladder reflexes, while inhibition from afferents in the dorsal clitoris nerve remained unchanged. It is concluded that the segmental bladder C fibre reflex and the spino-ponto-spinal A? micturition reflex are both targets of recurrent inhibition from bladder parasympathetic preganglionic neurones and that the effect involves an enkephalinergic mechanism. PMID:16809367

  15. Reflex inhibition of human soleus muscle during fatigue.

    PubMed Central

    Garland, S J; McComas, A J

    1990-01-01

    1. Human soleus muscles were fatigued under ischaemic conditions by intermittent stimulation at 15 Hz. When maximal voluntary plantarflexion was then attempted, the loss of torque was found to be associated with a reduction in voluntary EMG activity. 2. The decrease in EMG activity could not have been due to 'exhaustion' of descending motor drive in the central nervous system since fatigue had been induced by electrical stimulation of peripheral nerve fibres. Similarly, the decrease could not be explained by changes at the neuromuscular junction or muscle fibre membrane, since changes in the M wave (evoked muscle compound action potential) were relatively modest. 3. When the excitability of the soleus motoneurones was tested during fatigue, using the H (Hoffmann) reflex, it was found to be significantly reduced. Control experiments with ischaemia or electrical stimulation, but without fatigue, failed to demonstrate any significant effects on reflex excitability. 4. The findings in this study favour the concept of reflex inhibition of alpha-motoneurones during fatigue. PMID:2277345

  16. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  17. Protective Role of Aerodigestive Reflexes Against Aspiration: Study on Subjects With Impaired and Preserved Reflexes

    PubMed Central

    DUA, KULWINDER; SURAPANENI, SRI NAVEEN; KURIBAYASHI, SHIKO; HAFEEZULLAH, MOHAMMED; SHAKER, REZA

    2012-01-01

    BACKGROUND & AIMS Direct evidence to support the airway protective function of aerodigestive reflexes triggered by pharyngeal stimulation was previously demonstrated by abolishing these reflexes by topical pharyngeal anesthesia in normal subjects. Studies have also shown that these reflexes deteriorate in cigarette smokers. Aim of this study was to determine the influence of defective pharyngeal aerodigestive reflexes on airway protection in cigarette smokers. METHODS Pharyngoglottal Closure reflex; PGCR, Pharyngo-UES Contractile reflex; PUCR, and Reflexive Pharyngeal Swallow; RPS were studied in 15 healthy non-smokers (24.2 ± 3.3 SD y, 7 males) and 15 healthy chronic smokers (27.3 ± 8.1, 7 males). To elicit these reflexes and to evaluate aspiration, colored water was perfused into the hypopharynx at the rate of 1 mL/min. Maximum volume of water that can safely dwell in the hypopharynx before spilling into the larynx (Hypopharyngeal Safe Volume; HPSV) and the threshold volume to elicit PGCR, PUCR, and RPS were determined in smokers and results compared with non-smokers. RESULTS At baseline, RPS was elicited in all non-smokers (100%) and in only 3 of 15 smokers (20%; P < .001). None of the non-smokers showed evidence of laryngeal spillage of water, whereas 12 of 15 smokers with absent RPS had laryngeal spillage. Pharyngeal anesthesia abolished RPS reflex in all non-smokers resulting in laryngeal spillage. The HPSV was 0.61 ± 0.06 mL and 0.76 ± 0.06 mL in non-smokers and smokers respectively (P = .1). CONCLUSIONS Deteriorated reflexive pharyngeal swallow in chronic cigarette smokers predispose them to risks of aspiration and similarly, abolishing this reflex in non-smokers also results in laryngeal spillage. These observations directly demonstrate the airway protective function of RPS. PMID:21420407

  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. The trigeminocardiac reflex – a comparison with the diving reflex in humans

    PubMed Central

    Lemaitre, Frederic; Schaller, Bernhard

    2015-01-01

    The trigeminocardiac reflex (TCR) has previously been described in the literature as a reflexive response of bradycardia, hypotension, and gastric hypermotility seen upon mechanical stimulation in the distribution of the trigeminal nerve. The diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, reduction of limb blood flow and a gradual rise in the mean arterial blood pressure. Although the two reflexes share many similarities, their relationship and especially their functional purpose in humans have yet to be fully elucidated. In the present review, we have tried to integrate and elaborate these two phenomena into a unified physiological concept. Assuming that the TCR and the DR are closely linked functionally and phylogenetically, we have also highlighted the significance of these reflexes in humans. PMID:25995761

  20. Stretch reflex gain in cat triceps surae muscles with compliant loads

    PubMed Central

    Serres, Sophie J De; Bennett, David J; Stein, Richard B

    2002-01-01

    The triceps surae (TS) stretch reflex was measured in decerebrate cats during crossed extensor stimulation (tonic contractions) and after spinalization during rhythmic locomotor activity. The TS reflex force in response to a short pulse stretch measured during tonic contractions at low level of background activity was greater than when more background activity was present at the time of application of stretch. In contrast, the reflex force measured during rhythmic contractions was very small at low level of background force (flexion phase) and increased at moderate and high levels of background activity (extension phase). Thus, even in reduced preparations, a task modulation of the stretch reflex occurs. Throughout the experimental procedure, the torque motor used to stretch the muscles behaved like a spring of a preset compliance (from isometric to very compliant). A reflex model was used to simulate the responses obtained experimentally. The gain of the stretch reflex loop was estimated for each load condition and both behavioural tasks. The reflex loop gain was significantly larger as the compliance of the external load increased for both tonic and rhythmic contractions, although to a lesser extent in the phasically activated muscles. During rhythmic locomotor contractions the gain was less than 1, assuring stability of the system. In contrast, during tonic contractions against a compliant load the gain exceeded 1, consistent with the instability (oscillations, clonus) seen at times under these load conditions. However, the high gain and instability was only transient, since repeated stretch reduced the gain. Thus, non-linearities in the system assured vigorous responses at the onset of perturbations, but then weaker responses to ongoing perturbations to reduce the chance of feedback instability (clonus). PMID:12482905

  1. Using ESO Reflex with Web Services

    NASA Astrophysics Data System (ADS)

    Järveläinen, P.; Savolainen, V.; Oittinen, T.; Maisala, S.; Ullgrén, M. Hook, R.

    2008-08-01

    ESO Reflex is a prototype graphical workflow system, based on Taverna, and primarily intended to be a flexible way of running ESO data reduction recipes along with other legacy applications and user-written tools. ESO Reflex can also readily use the Taverna Web Services features that are based on the Apache Axis SOAP implementation. Taverna is a general purpose Web Service client, and requires no programming to use such services. However, Taverna also has some restrictions: for example, no numerical types such integers. In addition the preferred binding style is document/literal wrapped, but most astronomical services publish the Axis default WSDL using RPC/encoded style. Despite these minor limitations we have created simple but very promising test VO workflow using the Sesame name resolver service at CDS Strasbourg, the Hubble SIAP server at the Multi-Mission Archive at Space Telescope (MAST) and the WESIX image cataloging and catalogue cross-referencing service at the University of Pittsburgh. ESO Reflex can also pass files and URIs via the PLASTIC protocol to visualisation tools and has its own viewer for VOTables. We picked these three Web Services to try to set up a realistic and useful ESO Reflex workflow. They also demonstrate ESO Reflex abilities to use many kind of Web Services because each of them requires a different interface. We describe each of these services in turn and comment on how it was used

  2. Elbow flexion response as another primitive reflex.

    PubMed

    Sudo, Kazumasa; Matsuyama, Tomokiho; Goto, Yoshiro; Matsumoto, Akihisa; Tashiro, Kunio

    2002-04-01

    In daily clinical practice we noticed that patients with intellectual impairment spontaneously flex the elbow within a few seconds of the forearm being manipulated during routine examination of spasticity of the muscles in the upper extremities. We termed this phenomenon elbow flexion response (EFR), and prospectively studied it in 229 patients who underwent in-hospital rehabilitation following brain damage. Evaluation of each patient included EFR, patient profile, ability to communicate, scores on three parameters from various intelligence tests, scores on seven parameters testing primitive reflexes, and scores on three parameters describing personality. We investigated for relationships among these parameters. Consequently, although EFR rarely have a statistical association with the varied profiles of patients, patients with bilateral lesion or bilateral paresis demonstrated significantly more marked EFR than those with unilateral lesion or unilateral paresis. Patients with involvement of the frontal lobe showed significantly more marked EFR than those without damage in this area. Elbow flexion responses occurred significantly more frequently in relation with lower scores on intelligence and occurred with significantly higher frequency in conjunction with the more marked appearance of conventional primitive reflexes. Therefore, we conclude that EFR have a strong association with intelligence and with the existence of frontal lobe lesion, and their mode of clinical presentation parallels that of primitive reflexes particularly that of the grasp reflex. We propose that EFR could be referred as a variation of the grasp reflex occurring in the more proximal or axial part of the body. PMID:11952915

  3. Modulation of human vestibular reflexes with increased postural threat.

    PubMed

    Horslen, Brian C; Dakin, Christopher J; Inglis, J Timothy; Blouin, Jean-Sébastien; Carpenter, Mark G

    2014-08-15

    Anxiety and arousal have been shown to facilitate human vestibulo-ocular reflexes, presumably through direct neural connections between the vestibular nuclei and emotional processing areas of the brain. However, the effects of anxiety, fear and arousal on balance-relevant vestibular reflexes are currently unknown. The purpose of this study was to manipulate standing height to determine whether anxiety and fear can modulate the direct relationship between vestibular signals and balance reflexes during stance. Stochastic vestibular stimulation (SVS; 2-25 Hz) was used to evoke ground reaction forces (GRF) while subjects stood in both LOW and HIGH surface height conditions. Two separate experiments were conducted to investigate the SVS-GRF relationship, in terms of coupling (coherence and cumulant density) and gain, in the medio-lateral (ML) and antero-posterior (AP) directions. The short- and medium-latency cumulant density peaks were both significantly increased in the ML and AP directions when standing in HIGH, compared to LOW, conditions. Likewise, coherence was statistically greater between 4.3 Hz and 6.7 Hz in the ML, and between 5.5 and 17.7 Hz in the AP direction. When standing in the HIGH condition, the gain of the SVS-GRF relationship was increased 81% in the ML direction, and 231% in the AP direction. The significant increases in coupling and gain observed in both experiments demonstrate that vestibular-evoked balance responses are augmented in states of height-induced postural threat. These data support the possibility that fear or anxiety-mediated changes to balance control are affected by altered central processing of vestibular information. PMID:24973412

  4. Modulation of human vestibular reflexes with increased postural threat

    PubMed Central

    Horslen, Brian C; Dakin, Christopher J; Inglis, J Timothy; Blouin, Jean-Sébastien; Carpenter, Mark G

    2014-01-01

    Anxiety and arousal have been shown to facilitate human vestibulo-ocular reflexes, presumably through direct neural connections between the vestibular nuclei and emotional processing areas of the brain. However, the effects of anxiety, fear and arousal on balance-relevant vestibular reflexes are currently unknown. The purpose of this study was to manipulate standing height to determine whether anxiety and fear can modulate the direct relationship between vestibular signals and balance reflexes during stance. Stochastic vestibular stimulation (SVS; 2–25 Hz) was used to evoke ground reaction forces (GRF) while subjects stood in both LOW and HIGH surface height conditions. Two separate experiments were conducted to investigate the SVS–GRF relationship, in terms of coupling (coherence and cumulant density) and gain, in the medio-lateral (ML) and antero-posterior (AP) directions. The short- and medium-latency cumulant density peaks were both significantly increased in the ML and AP directions when standing in HIGH, compared to LOW, conditions. Likewise, coherence was statistically greater between 4.3 Hz and 6.7 Hz in the ML, and between 5.5 and 17.7 Hz in the AP direction. When standing in the HIGH condition, the gain of the SVS–GRF relationship was increased 81% in the ML direction, and 231% in the AP direction. The significant increases in coupling and gain observed in both experiments demonstrate that vestibular-evoked balance responses are augmented in states of height-induced postural threat. These data support the possibility that fear or anxiety-mediated changes to balance control are affected by altered central processing of vestibular information. PMID:24973412

  5. Retrieval interference in reflexive processing: experimental evidence from Mandarin, and computational modeling

    PubMed Central

    Jäger, Lena A.; Engelmann, Felix; Vasishth, Shravan

    2015-01-01

    We conducted two eye-tracking experiments investigating the processing of the Mandarin reflexive ziji in order to tease apart structurally constrained accounts from standard cue-based accounts of memory retrieval. In both experiments, we tested whether structurally inaccessible distractors that fulfill the animacy requirement of ziji influence processing times at the reflexive. In Experiment 1, we manipulated animacy of the antecedent and a structurally inaccessible distractor intervening between the antecedent and the reflexive. In conditions where the accessible antecedent mismatched the animacy cue, we found inhibitory interference whereas in antecedent-match conditions, no effect of the distractor was observed. In Experiment 2, we tested only antecedent-match configurations and manipulated locality of the reflexive-antecedent binding (Mandarin allows non-local binding). Participants were asked to hold three distractors (animate vs. inanimate nouns) in memory while reading the target sentence. We found slower reading times when animate distractors were held in memory (inhibitory interference). Moreover, we replicated the locality effect reported in previous studies. These results are incompatible with structure-based accounts. However, the cue-based ACT-R model of Lewis and Vasishth (2005) cannot explain the observed pattern either. We therefore extend the original ACT-R model and show how this model not only explains the data presented in this article, but is also able to account for previously unexplained patterns in the literature on reflexive processing. PMID:26074829

  6. Retrieval interference in reflexive processing: experimental evidence from Mandarin, and computational modeling.

    PubMed

    Jäger, Lena A; Engelmann, Felix; Vasishth, Shravan

    2015-01-01

    We conducted two eye-tracking experiments investigating the processing of the Mandarin reflexive ziji in order to tease apart structurally constrained accounts from standard cue-based accounts of memory retrieval. In both experiments, we tested whether structurally inaccessible distractors that fulfill the animacy requirement of ziji influence processing times at the reflexive. In Experiment 1, we manipulated animacy of the antecedent and a structurally inaccessible distractor intervening between the antecedent and the reflexive. In conditions where the accessible antecedent mismatched the animacy cue, we found inhibitory interference whereas in antecedent-match conditions, no effect of the distractor was observed. In Experiment 2, we tested only antecedent-match configurations and manipulated locality of the reflexive-antecedent binding (Mandarin allows non-local binding). Participants were asked to hold three distractors (animate vs. inanimate nouns) in memory while reading the target sentence. We found slower reading times when animate distractors were held in memory (inhibitory interference). Moreover, we replicated the locality effect reported in previous studies. These results are incompatible with structure-based accounts. However, the cue-based ACT-R model of Lewis and Vasishth (2005) cannot explain the observed pattern either. We therefore extend the original ACT-R model and show how this model not only explains the data presented in this article, but is also able to account for previously unexplained patterns in the literature on reflexive processing. PMID:26074829

  7. Reflex sympathetic dystrophy: an enigmatic improvement with spinal manipulation

    PubMed Central

    Bortolotto, James

    2000-01-01

    Reflex Sympathetic Dystrophy (RSD) or complex regional pain syndrome, is an extremely painful and disabling condition commonly seen following trauma. Its early recognition and treatment is most critical for a favorable prognosis. Although its diagnosis and treatments vary, neuroblockade is the treatment of choice. Very little has been reported in the literature in regards to manipulation as an early treatment modality to improve joint mobility and reduce pain and future disability. This case report reviews one case presentation of RSD where dramatic results followed cervical spine manipulation.

  8. Reflexive composites: self-healing composite structures

    NASA Astrophysics Data System (ADS)

    Margraf, Thomas W., Jr.; Barnell, Thomas J.; Havens, Ernie; Hemmelgarn, Christopher D.

    2008-03-01

    Cornerstone Research Group Inc. has developed reflexive composites achieving increased vehicle survivability through integrated structural awareness and responsiveness to damage. Reflexive composites can sense damage through integrated piezoelectric sensing networks and respond to damage by heating discrete locations to activate the healable polymer matrix in areas of damage. The polymer matrix is a modified thermoset shape memory polymer that heals based on phenomena known as reptation. In theory, the reptation healing phenomena should occur in microseconds; however, during experimentation, it has been observed that to maximize healing and restore up to 85 % of mechanical properties a healing cycle of at least three minutes is required. This paper will focus on work conducted to determine the healing mechanisms at work in CRG's reflexive composites, the optimal healing cycles, and an explanation of the difference between the reptation model and actual healing times.

  9. A reflex resonance model of vocal vibrato

    NASA Astrophysics Data System (ADS)

    Titze, Ingo R.; Story, Brad; Smith, Marshall; Long, Russel

    2002-05-01

    A reflex mechanism with a long latency (>40 ms) is implicated as a plausible cause of vocal vibrato. At least one pair of agonist-antagonist muscles that can change vocal-fold length is needed, such as the cricothyroid muscle paired with the thyroarytenoid muscle, or the cricothyroid muscle paired with the lateral cricoarytenoid muscle or a strap muscle. Such an agonist-antagonist muscle pair can produce negative feedback instability in vocal-fold length with this long reflex latency, producing oscillations on the order of 5-7 Hz. It is shown that singers appear to increase the gain in the reflex loop to cultivate the vibrato, which grows out of a spectrum of 0-15-Hz physiologic tremors in raw form.

  10. 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

  11. Neural reflexes in inflammation and immunity.

    PubMed

    Andersson, Ulf; Tracey, Kevin J

    2012-06-01

    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

  12. Proposed equation between flexor carpi radialis H-reflex latency and upper limb length

    PubMed Central

    Khosrawi, Saeid; Taheri, Parisa; Hashemi, Seyed Hasan

    2015-01-01

    Background: H-reflex is a valuable electrophysiological technique for assessing nerve conduction through entire length of afferent and efferent pathways, especially nerve roots and proximal segments of peripheral nerves. The aim of this study was to investigate the relation between normal values of flexor carpi radialis (FCR) H-reflex latency, upper limb length and age in normal subjects, and to determine whether there is any regression equation between them. Methods: By considering the criteria of inclusion and exclusion, 120 upper limbs of 69 normal volunteers (68 hands of 39 men and 52 hands of 30 women) with the mean age of 39.8 ± 11.2 years participated in this study. FCR H-reflex was obtained by standard electrodiagnostic techniques, and its onset latency was recorded. Upper limb length and arm length were measured in defined position. The degree of association between these variables was determined with Pearson correlation and linear regression was used for obtaining the proposed relations. Results: Mean FCR H-reflex latency was found to be 15.88 ± 1.27 ms. There was a direct linear correlation between FCR H-reflex latency and upper limb length (r = 0.647) and also arm length (r = 0.574), but there was no significant correlation between age and FCR H-reflex latency (P = 0.260). Finally, based on our findings, we tried to formulate these relations by statistical methods. Conclusion: We found that upper limb length and arm length are good predictive values for estimation of normal FCR H-reflex latency but age, in the range of 20-60 years old, has no correlation with its latency. This estimation could have practical indications in pathologic conditions. PMID:25874056

  13. 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

  14. Voluntary reaction time and long-latency reflex modulation.

    PubMed

    Forgaard, Christopher J; Franks, Ian M; Maslovat, Dana; Chin, Laurence; Chua, Romeo

    2015-12-01

    Stretching a muscle of the upper limb elicits short (M1) and long-latency (M2) reflexes. When the participant is instructed to actively compensate for a perturbation, M1 is usually unaffected and M2 increases in size and is followed by the voluntary response. It remains unclear if the observed increase in M2 is due to instruction-dependent gain modulation of the contributing reflex mechanism(s) or results from voluntary response superposition. The difficulty in delineating between these alternatives is due to the overlap between the voluntary response and the end of M2. The present study manipulated response accuracy and complexity to delay onset of the voluntary response and observed the corresponding influence on electromyographic activity during the M2 period. In all active conditions, M2 was larger compared with a passive condition where participants did not respond to the perturbation; moreover, these changes in M2 began early in the appearance of the response (?50 ms), too early to be accounted for by voluntary overlap. Voluntary response latency influenced the latter portion of M2, with the largest activity seen when accuracy of limb position was not specified. However, when participants aimed for targets of different sizes or performed movements of various complexities, reaction time differences did not influence M2 period activity, suggesting voluntary activity was sufficiently delayed. Collectively, our results show that while a perturbation applied to the upper limbs can trigger a voluntary response at short latency (<100 ms), instruction-dependent reflex gain modulation remains an important contributor to EMG changes during the M2 period. PMID:26538606

  15. Reflex sympathetic dystrophy in a 12-year-old twin with comorbid conversion disorder in both twins.

    PubMed

    Jaworowski, S; Allen, R C; Finkelstein, E

    1998-12-01

    A case of reflex sympathetic dystrophy is presented in a 12-year-old girl with comorbid conversion disorder. Her identical twin also had a conversion disorder. This is the first reported case of coexistence of reflex sympathetic dystrophy and conversion disorder. It is important for clinicians to be aware that these conditions may coexist since the presentation of symptoms differ, even though there are shared features of treatment. PMID:9928655

  16. Sudden onset Oculo-cardiac Reflex post-traumatic eye injury in PNG: a case study and discussion.

    PubMed

    Grogan, Aaron D

    2014-08-01

    This case study examines the onset of traumatic OCR--Oculo-cardiac Reflex--in the remote southern highlands of PNG. The spontaneous occurrence of OCR post-trauma in the clinical setting leads to sudden onset bradycardia, nausea and hypotension, resulting in cardiovascular compromise and deteriorating clinical conditions. Initial recognition of the characteristics of OCR will prepare the clinician to deal with the sequence of events that arise post the reflex initiation. PMID:25113316

  17. The grasp reflex: a symptom in need of treatment.

    PubMed

    Mestre, Tiago; Lang, Anthony E

    2010-11-15

    The grasp reflex is one of the primitive reflexes frequently observed in neurodegenerative diseases. However, quality of life and treatment of the grasp reflex are neglected in the literature. Following two brief case vignettes of patients seen recently who experienced disability from a grasp reflex, we briefly review its phenomenology, anatomy-physiology and epidemiology in neurodegenerative movement disorders, and assess the limited current literature regarding the quality of life and treatment. PMID:20848621

  18. Evaluating the Reflexive Practices in a Learning Experience

    ERIC Educational Resources Information Center

    Bruno, Andreina; Galuppo, Laura; Gilardi, Silvia

    2011-01-01

    Reflexivity is a primary requirement for professional work. Our aim was to describe a methodology suitable for detecting the development of reflexive practice through the analysis of 59 Master's degree students' journals. We explore the use and changes of reflexive practice in relation to the settings and activities of the course using analysis of…

  19. 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…

  20. The Limits of Institutional Reflexivity in Bulgarian Universities

    ERIC Educational Resources Information Center

    Slantcheva, Snejana

    2004-01-01

    This article focuses on the notion of institutional reflexivity. Its theoretical framework is based on the views of a group of sociologists--Anthony Giddens, Ulrich Beck, Scott Lash--who developed the concept of reflexive modernization. The article applies the notion of institutional reflexivity to the field of higher education and reviews the…

  1. Snout and Visual Rooting Reflexes in Infantile Autism. Brief Report.

    ERIC Educational Resources Information Center

    Minderaa, Ruud B.; And Others

    1985-01-01

    The authors conducted extensive neurological evaluations of 42 autistic individuals and were surprised to discover a consistently positive snout reflex in most of them. Difficulties with assessing the reflex are noted. The authors then reassessed the Ss for a series of primitive reflexes which are interpreted as signs of diffuse cortical brain…

  2. 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 (±)-α-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

  3. Identification of intrinsic and reflex ankle stiffness components in stroke patients.

    PubMed

    Galiana, Laura; Fung, Joyce; Kearney, Robert

    2005-09-01

    Reflex and intrinsic contributions to ankle stiffness were examined in 11 stroke patients with clinical evidence of ankle spasticity and nine gender-matched and age-matched controls. Subjects lay supine with one foot placed in a custom-fitted boot attached to an electro-hydraulic actuator. They were instructed to relax while pseudo-random binary sequence perturbations were applied to their ankle joint. The ankle position and torque, as well as EMG from the ankle dorsiflexors and plantarflexors were recorded. These were used to identify reflex and intrinsic components of ankle stiffness, using a non-linear, parallel-cascade, system identification method. Results demonstrated that the majority of stroke patients (7/11) had ankle stiffness similar to that of control subjects. In contrast, a minority of stroke patients (4/11) had an abnormal increase in ankle stiffness, most of which could be attributed to an increased reflex gain. Reflex stiffness increased as the ankle was dorsiflexed in all subjects. These results differ from a previous study showing that reflex gain and intrinsic stiffness were increased in all patients with spinal cord injury. This difference may reflect the different topography of the lesions in the two neurological conditions. PMID:15991034

  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. On Becoming a Critically Reflexive Practitioner

    ERIC Educational Resources Information Center

    Cunliffe, Ann L.

    2004-01-01

    Critically reflexive practice embraces subjective understandings of reality as a basis for thinking more critically about the impact of our assumptions, values, and actions on others. Such practice is important to management education, because it helps us understand how we constitute our realities and identities in relational ways and how we can…

  6. 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…

  7. Plasma quiescence in a reflex discharge

    SciTech Connect

    Jerde, L.; Friedman, S.; Carr, W.; Seidl, M.

    1980-02-01

    A thermionic cathode reflex discharge and the plasma it produces are studied. It is found that extremely quiescent plasmas can be produced when the electron-loss rate due to classical diffusion is equal to the ion-loss rate. Particle and power balances for the quiescent plasma are obtained, and the average electron energy loss per ion produced is determined.

  8. 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…

  9. Reflexive Learning: Stages towards Wisdom with Dreyfus

    ERIC Educational Resources Information Center

    McPherson, Ian

    2005-01-01

    The Dreyfus (2001) account of seven stages of learning is considered in the context of the Dreyfus (1980s) account of five stages of skill development. The two new stages, Mastery and Practical Wisdom, make more explicit certain themes implicit in the five-stage account. In this way Dreyfus (2001) encourages a more reflexive approach. The themes…

  10. Reflex Anuria After Renal Tumor Embolization

    SciTech Connect

    Kervancioglu, Selim Sirikci, Akif; Erbagci, Ahmet

    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.

  11. 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…

  12. 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…

  13. 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…

  14. Doing Reflexivity: Moments of Unbecoming and Becoming

    ERIC Educational Resources Information Center

    Fox, Alison; Allan, Julie

    2014-01-01

    This paper offers an account of a reflexive "trip" undertaken by a professional doctoral student and her supervisor. It presents a series of vignettes which offer an account of unbecomings and becomings encountered by the student. Making use of a dialogic approach in which the supervisor responds to the student, we suggest this method of…

  15. Reconceptualizing rigour: the case for reflexivity.

    PubMed

    Koch, T; Harrington, A

    1998-10-01

    This paper is a critical review of recent discussions of rigour in nursing research. We will argue that 'borrowing' evaluation criteria from one paradigm of inquiry and applying them to another is problematic. We attempt to map the 'rigour' field and add a dimension to the existing debate about rigour and qualitative research through inclusion of reflexivity guided by philosophical hermeneutics. We describe reflexivity and appeal to writers to incorporate a reflexive account into their research product by signposting to readers 'what is going on' while researching. We contend that researchers bring to the research product, data generated, a range of literature, a positioning of this literature, a positioning of oneself, and moral socio-political contexts. We suggest that reflexive research is characterized by ongoing self-critique and self-appraisal and that the research product can be given shape by the politics of location and positioning. We emphasize that in the creation of a text (the research product) it is desirable that the researcher be a skilled writer. Finally we claim that if the research product is well signposted, the readers will be able to travel easily through the worlds of the participants and makers of the text (the researchers) and decide for themselves whether the text is believable or plausible (our terms for rigour). PMID:9829678

  16. Effect of diabetes on some primitive reflexes.

    PubMed

    Volpe, G; Della Rocca, G; Brescia Morra, V; Belfiore, G; Coppola, G; Campanella, G; Orefice, G

    2000-07-01

    Primitive reflexes (PRs) are present in newborns; they disappear as the brain matures and increase in frequency in healthy elderly individuals. Primitive reflexes are more frequent in some neurological disorders than in age-matched controls. The aim of this study was to investigate the effect of diabetes on some PRs. We examined three PRs (glabellar tap, snout and palmomental reflexes) in 376 subjects: 111 normal age-matched controls, 60 patients with cerebrovascular disease (CVD) and 205 patients with type 2 diabetes mellitus. The latter patients were divided into three groups: (1) diabetics without neurological complications (D); (2) diabetics with cerebrovascular disease (D-CVD); and (3) diabetics with polyneuropathy (D-PN). The frequency of PRs was increased in CVD, unchanged in D-CVD (except palmomental) and greatly reduced in D and D-PN. It is possible that the vascular lesions in perforating arteries of the pons in diabetic subjects, previously studied in some pathological reports, can account for the reduced occurrence of primitive reflex responses. PMID:10971599

  17. 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

  18. Go Your Own Way: Lifelong Learning and Reflexive Autobiographies in Postmodernity.

    ERIC Educational Resources Information Center

    Miller, Nod; Edwards, Richard

    2000-01-01

    Autobiographical accounts of two adult educators address questions of what it means to be an adult educator in an environment of individualization and reflexivity. Cultural conditions that give rise to similarities and differences in their accounts, such as postmodernism and popular culture, are identified. (SK)

  19. Voluntary and involuntary ventilation do not alter the human inspiratory muscle loading reflex.

    PubMed

    Murray, N P S; McKenzie, D K; Gandevia, S C; Butler, J E

    2010-07-01

    The reflex mechanism of the short-latency inhibitory reflex to transient loading of human inspiratory muscles is unresolved. Muscle afferents mediate this reflex, but they may act via pontomedullary inspiratory centers, other bulbar networks, or spinal circuits. We hypothesized that altered chemical drive to breathe would alter the initial inhibitory reflex if the neural pathways involve inspiratory medullary centers. Inspiration was transiently loaded in 11 subjects during spontaneous hypercapnic hyperpnea and matched voluntary hyperventilation. Electromyographic activity was recorded bilaterally from scalene muscles with surface electrodes. The latencies of the initial inhibitory response (IR) onset (32 +/- 0.7 and 38 +/- 1 ms for spontaneous and voluntary conditions respectively, P < 0.001) and subsequent excitatory response (ER) onset (80 +/- 2.9 and 78 +/- 2.6 ms, respectively, P = 0.46) and the normalized sizes of IR (65 +/- 2 and 67 +/- 3%, respectively, P = 0.50) and ER (51 +/- 8 and 69 +/- 6%, respectively, P = 0.005) were measured. Mean end-tidal Pco(2) was 43 +/- 1.5 Torr with dead space ventilation and was 14 +/- 0.6 Torr with matched voluntary hyperventilation (P < 0.001). A mean minute volume >30 liters was achieved in both conditions. The absence of significant difference in the size of the IR suggested that the IR reflex arc does not transit the brain stem inspiratory centers and that the reflex may be integrated at a spinal level. In voluntary hyperventilation, an initial excitation occurred more frequently and, consequently, the IR onset latency was significantly longer. The size of the later ER was also greater during voluntary hyperventilation, which is consistent with it being mediated via longer, presumably cortical, pathways, which are influenced by voluntary drive. PMID:20395542

  20. Modulation of the initial light reflex during affective picture viewing.

    PubMed

    Henderson, Robert R; Bradley, Margaret M; Lang, Peter J

    2014-09-01

    An initial reflexive constriction of the pupil to stimulation-the light reflex-is primarily modulated by brightness, but is attenuated when participants are under threat of shock (i.e., fear-inhibited light reflex). The present study assessed whether the light reflex is similarly attenuated when viewing emotional pictures. Pupil diameter was recorded while participants viewed erotic, violent, and neutral scenes that were matched in brightness; scrambled versions identical in brightness were also presented as an additional control. Compared to viewing neutral scenes, the light reflex was reliably modulated by hedonic content, with significant attenuation both when viewing unpleasant as well as pleasant pictures. No differences in the light reflex were found among scrambled versions. Thus, emotional modulation of the initial light reflex is not confined to a context of fear and is not indicative of brightness differences when viewing pictures of natural scenes. PMID:24849784

  1. Modulation of stretch reflex excitability during quiet human standing.

    PubMed

    Bock, P J; Kearney, R E; Forster, S M; Wagner, R

    2004-01-01

    Stretch reflex excitability was measured during quiet standing by using a bilateral electro-hydraulic actuator to apply perturbations of angular position to the ankle. Subjects were instructed to stand quietly while pulse displacements were applied at random time intervals. Position, torque, gastrocnemius soleus EMG, tibialis anterior EMG, heel position, tibia angle, femur angle, and sacrum angle were measured. Activation level and reflex excitability varied substantially from trial to trial - reflex torque decreased as the background torque level increased; while reflex EMG increased when background torque increased. This behavior is consistent with previous findings in prone subjects. Reflex torque for a given activation level was found to vary with the initial torque derivative. Negative torque derivatives produced greater reflex excitation then their positive counterparts. These findings suggest that reflex excitability in quiet human standing is modulated to optimize balance. PMID:17271353

  2. Modulation of the initial light reflex during affective picture viewing

    PubMed Central

    Henderson, Robert R.; Bradley, Margaret M.; Lang, Peter J.

    2014-01-01

    An initial reflexive constriction of the pupil to stimulation – the light reflex – is primarily modulated by brightness, but is attenuated when participants are under threat of shock (e.g. "fear-inhibited light reflex").The present study assessed whether the light reflex is similarly attenuated when viewing emotional pictures. Participants viewed erotic, violent, and neutral scenes that were matched in brightness; as an additional control, scrambled versions identical in brightness were also presented. Compared to viewing neutral scenes, the light reflex was reliably modulated by hedonic content, with significant attenuation both when viewing unpleasant, as well as pleasant, pictures. No differences in the light reflex were found among scrambled versions. Modulation of the initial light reflex is therefore not confined to a context of fear, and also is not indicative of differences in brightness when viewing pictures of natural scenes. PMID:24849784

  3. 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.

  4. Hoffmann reflex is increased after 14 days of daily repeated Achilles tendon vibration for the soleus but not for the gastrocnemii muscles.

    PubMed

    Lapole, Thomas; Pérot, Chantal

    2012-02-01

    In a previous study, Achilles tendon vibrations were enough to improve the triceps surae (TS) activation capacities and also to slightly increase TS Hoffmann reflex (H-reflex) obtained by summing up soleus (Sol) and gastrocnemii (GM and GL) EMGs. The purpose of the present study was to analyze separately Sol and GM or GL reflexes to account for different effects of the vibrations on the reflex excitability of the slow soleus and of the gastrocnemii muscles. A control group (n = 13) and a vibration group (n = 16) were tested in pre-test and post-test conditions. The Achilles tendon vibration program consisted of 1 h of daily vibration (frequency: 50 Hz) applied during 14 days. Maximal Sol, GM and GL H-reflexes, and M-waves were recorded, and their H(max)/M(max) ratios gave the index of reflex excitability. After the vibration protocol, only Sol H(max)/M(max) was enhanced (p < 0.001). The enhanced Sol reflex excitability after vibration is in favor of a decrease in the pre-synaptic inhibition due to the repeated vibrations and the high solicitation of the reflex pathway. Those results of a short period of vibration applied at rest may be limited to the soleus because of its high density in muscle spindles and slow motor units, both structures being very sensitive to vibrations. PMID:22148919

  5. Respiratory reflexes in the anesthetized miniature swine.

    PubMed

    Adams, L; Schneider, D A; Schertel, E R; Strong, E B; Green, J F

    1987-12-01

    To assess the suitability of the miniature swine for studies of the control of breathing we evaluated the response of these animals to commonly used respiratory stimuli. Hanford miniature pigs were anesthetized with alpha chloralose and allowed to breathe spontaneously. Rapid lung inflations induced a prolonged expiratory pause proportional to load. Mechanical stimulation of the upper airways induced coughing. Central venous injections of C-fiber stimulants produced bradycardia, hypotension with apnea and/or rapid shallow breathing. CO2 rebreathing increased ventilation primarily through an increase in tidal volume; inspiratory time was not changed. Bilateral vagotomy caused a slower, deeper pattern of breathing, and significantly attenuated the ventilatory response to CO2; all other reflexes were abolished by vagotomy. Cooling the vagus nerves caused reversible blockade of the cough, inflation and C-fiber mediated reflexes in that order. We conclude that the pig can serve as a useful animal in which to study the control of breathing. PMID:3120264

  6. 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.

  7. Photic sneeze reflex in nephropathic cystinosis.

    PubMed Central

    Katz, B; Melles, R B; Swenson, M R; Schneider, J A

    1990-01-01

    Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis. PMID:2275931

  8. Photic sneeze reflex in nephropathic cystinosis.

    PubMed

    Katz, B; Melles, R B; Swenson, M R; Schneider, J A

    1990-12-01

    Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis. PMID:2275931

  9. Extremal Transitions from Nested Reflexive Polytopes

    NASA Astrophysics Data System (ADS)

    Fredrickson, Karl

    2015-05-01

    In this paper we look at the question of when an inclusion of reflexive polytopes determines a torically-defined extremal transition between smooth Calabi-Yau hypersurface families. We show this is always possible in dimensions two and three. However, in dimensions four and higher, obstructions can occur. This leads to a smooth projective family of Calabi-Yau threefolds that is birational to one of Batyrev's hypersurface families, but topologically distinct from all such families.

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

    PubMed

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

    2011-11-01

    Distraction from pain reduces pain perception, and imaging studies have suggested that this may at least partially be mediated by activation of descending pain inhibitory systems. Here, we used the nociceptive flexor reflex (RIII reflex) to directly quantify the effects of different distraction strategies on basal spinal nociception and its temporal summation. Twenty-seven healthy subjects participated in 3 distraction tasks (mental imagery, listening to preferred music, spatial discrimination of brush stimuli) and, in a fourth task, concentrated on the painful stimulus. Results show that all 3 distraction tasks reduced pain perception, but only the brush task also reduced the RIII reflex. The concentration-on-pain task increased both pain perception and the RIII reflex. The extent of temporal summation of pain perception and the extent of temporal summation of the RIII reflex were not affected by any of the tasks. These results suggest that some, but not all, forms of pain reduction by distraction rely on descending pain inhibition. In addition, pain reduction by distraction seems to preferentially affect mechanisms of basal nociceptive transmission, not of temporal summation. PMID:21925793

  11. Tendon-reflex testing in chronic demyelinating polyneuropathy.

    PubMed

    Kuruoglu, H R; Oh, S J

    1994-02-01

    We studied the tendon reflex (T-reflex) in 26 patients with acquired chronic demyelinating polyneuropathy (CDN), including 22 with chronic inflammatory demyelinating polyneuropathy (CIDP). In 7 patients reflexes were brisk or normal on clinical testing. The height adjusted T-reflex was abnormal in 25 (96%) cases, including 6 of 7 patients with brisk or normal reflexes on clinical testing. Mean latency (P < 0.01) and duration (P < 0.05) of the ankle and patellar tendon reflexes were significantly prolonged in the CIDP patients when compared to the controls. Mean latency in the CIDP patients was 152% of normal means. In 7 CIDP patients, the T-reflex latencies were prolonged beyond 150% of normal means. Thus, the T-reflex test is abnormal in a majority of patients with CDN, even in the presence of well-preserved clinical reflexes, and the T-reflex latency is a useful indicator of the presence of a demyelinating peripheral neuropathy in some patients. PMID:8114782

  12. Influence of Age on Patellar Tendon Reflex Response

    PubMed Central

    Chandrasekhar, Annapoorna; Abu Osman, Noor Azuan; Tham, Lai Kuan; Lim, Kheng Seang; Wan Abas, Wan Abu Bakar

    2013-01-01

    Background A clinical parameter commonly used to assess the neurological status of an individual is the tendon reflex response. However, the clinical method of evaluation often leads to subjective conclusions that may differ between examiners. Moreover, attempts to quantify the reflex response, especially in older age groups, have produced inconsistent results. This study aims to examine the influence of age on the magnitude of the patellar tendon reflex response. Methodology/Principal Findings This study was conducted using the motion analysis technique with the reflex responses measured in terms of knee angles. Forty healthy subjects were selected and categorized into three different age groups. Patellar reflexes were elicited from both the left and right patellar tendons of each subject at three different tapping angles and using the Jendrassik maneuver. The findings suggested that age has a significant effect on the magnitude of the reflex response. An angle of 45° may be the ideal tapping angle at which the reflex can be elicited to detect age-related differences in reflex response. The reflex responses were also not influenced by gender and were observed to be fairly symmetrical. Conclusions/Significance Neurologically normal individuals will experience an age-dependent decline in patellar reflex response. PMID:24260483

  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. Social orienting: reflexive versus voluntary control

    PubMed Central

    Hill, Julia L.; Patel, Saumil; Gu, Xue; Seyedali, Nassim S.; Bachevalier, Jocelyne; Sereno, Anne B.

    2010-01-01

    Many studies have shown that the direction of gaze of a face covertly facilitates the response to a target presented in the matching direction. In this study we seek to determine whether there exist separate reflexive and voluntary forms of such covert social orienting and how they interact with each other. We measured the effect of the predictive value of a gaze cue on manual choice reaction times. When the predictive value of the gaze cue was zero, a facilitatory cueing effect was still observed which peaked at a Cue onset to Target onset Delay (CTD) of 150 ms and largely diminished beyond a CTD of 500 ms. When the gaze cue was 100% predictive of the future location of the target, at CTDs greater than 200, the predictive cue resulted in a significantly greater facilitation of response than occurred with a non-predictive cue. These results suggest that given enough time (about 200 ms), the social cue is interpreted and a willful or voluntary spatially-specific social cueing effect occurs. In addition, we found that a predictive cue resulted in a significant slowing of the observer’s responses up to a CTD of 200 ms. These findings show that, similar to non-social spatial orienting, there appear to be two forms of social orienting including a reflexive component and voluntary component. We suggest a model of social orienting in which the voluntary social orienting system modulates tonic inhibition of the reflexive social orienting system. PMID:20673778

  15. 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

  16. Effect of airway inflammation on short-latency reflex inhibition to inspiratory loading in human scalene muscles.

    PubMed

    Murray, Nicholas P S; McKenzie, David K; Gandevia, Simon C; Butler, Jane E

    2012-04-30

    The short-latency reflex inhibition of human inspiratory muscles produced by loading is prolonged in asthma and obstructive sleep apnoea, both diseases involving airway and systemic inflammation. Both diseases also involve repetitive inspiratory loading. Although airway mucosal afferents are not critical components of the normal reflex arc, during airway inflammation, prolongation of the reflex may be caused by altered mucosal afferent sensitivity, or altered central processing of their inputs. We hypothesised that acute viral airway inflammation would replicate the reflex abnormality. The reflex was tested in 9 subjects with a "common cold" during both the acute infection and when well. Surface electrodes recorded electromyographic (EMG) activity bilaterally from scalene muscles. Latencies of the inhibitory response (IR) did not differ significantly (IR peak 67 vs 70 ms (p=0.12), and IR offset 87 vs 90 ms (p=0.23), between the inflamed and well conditions, respectively). There was no difference in any measure of the size of the reflex inhibition. PMID:22415066

  17. 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.

  18. Temporal order judgments are disrupted more by reflexive than by voluntary saccades.

    PubMed

    Yabe, Yoshiko; Goodale, Melvyn A; Shigemasu, Hiroaki

    2014-05-01

    We do not always perceive the sequence of events as they actually unfold. For example, when two events occur before a rapid eye movement (saccade), the interval between them is often perceived as shorter than it really is and the order of those events can be sometimes reversed (Morrone MC, Ross J, Burr DC. Nat Neurosci 8: 950-954, 2005). In the present article we show that these misperceptions of the temporal order of events critically depend on whether the saccade is reflexive or voluntary. In the first experiment, participants judged the temporal order of two visual stimuli that were presented one after the other just before a reflexive or voluntary saccadic eye movement. In the reflexive saccade condition, participants moved their eyes to a target that suddenly appeared. In the voluntary saccade condition, participants moved their eyes to a target that was present already. Similarly to the above-cited study, we found that the temporal order of events was often misjudged just before a reflexive saccade to a suddenly appearing target. However, when people made a voluntary saccade to a target that was already present, there was a significant reduction in the probability of misjudging the temporal order of the same events. In the second experiment, the reduction was seen in a memory-delay task. It is likely that the nature of the motor command and its origin determine how time is perceived during the moments preceding the motor act. PMID:24598516

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

    PubMed

    Nishino, Takashi

    2012-01-01

    Swallowing function, in humans, is very complex. Swallowing plays, not only an important role in food digestion, but also a major role in preventing the entrance of food and/or other materials into the lower respiratory tract. To achieve this, precise coordination is necessary between breathing and swallowing since the pharynx serves as a common pathway for both respiration and digestion. The swallowing reflex consists of afferent pathways, central integration, and efferent pathways. Any defect or disorder along reflex arc can cause a potential delay or impairment in swallow function. The swallowing reflex can be modulated not only by pathological factors but also by physiological factors. Among these, timing of swallows in relation to the phase of respiration may be the most important factor that determines the occurrence of pulmonary aspiration, since phases of inspiration and the expiration-inspiration transition are the most vulnerable for pulmonary aspiration. PMID:23316169

  20. Pulsed reflex ion source studies

    SciTech Connect

    Bickes, Jr., R. W.; O'Hagan, J. B.

    1980-11-01

    Parametric studies of demountable versions of the pulsed ion source used in Controlatron and Zetatron neutron tubes were carried out. The goal of these experiments, a continuation of earlier work by Bacon and O'Hagan, was to investigate the deuteron beam intensity as a function of source geometry, electrode materials, operating conditions and pulse length. Geometric variations produced only modest changes in the ion beam intensity; the most sensitive parameter was the length of the secondary cathode. There is some evidence that the addition of oxygen either in the gas feed or using alumina on the cathode surfaces can increase the atomic ion fraction. The lowest reliable operating source pressure was approximately 1.33 Pa. The longest pulse length was about 1.2 ms. Difficulties in measuring the ion currents are discussed and suggestions for future experiments are briefly outlined.

  1. 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

  2. The exercise pressor reflex and peripheral artery disease

    PubMed Central

    Stone, Audrey J.; Kaufman, Marc P.

    2014-01-01

    The exercise pressor reflex contributes to increases in cardiovascular and ventilatory function during exercise. These reflexive increases are caused by both mechanical and metabolic stimulation of Group III and IV afferents with endings in contracting skeletal muscle. Patients with peripheral artery disease (PAD) have an augmented exercise pressor reflex. Recently, an animal model of PAD was established which allows further investigation of possible mechanisms involved in this augmented reflex. Earlier studies have identified ASIC3 channels, bradykinin receptors, P2X receptors, endoperoxide receptors, and thromboxane receptors as playing a role in evoking the exercise pressor reflex in healthy rats. This review focuses on recent studies using a rat model of PAD in order to determine possible mechanisms contributing to the exaggerated exercise pressor reflex seen in patients with this disease. PMID:25458431

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

    PubMed Central

    Yang, Chung-Yong

    2015-01-01

    Hyperactive reflexes are commonly observed in patients with spinal cord injury (SCI) but there is a lack of convenient and quantitative characterizations. Patellar tendon reflexes were examined in nine SCI patients and ten healthy control subjects by tapping the tendon using a hand-held instrumented hammer at various knee flexion angles, and the tapping force, quadriceps EMG, and knee extension torque were measured to characterize patellar tendon reflexes quantitatively in terms of the tendon reflex gain (Gtr), contraction rate (Rc), and reflex loop time delay (td). It was found that there are significant increases in Gtr and Rc and decrease in td in patients with spinal cord injury as compared to the controls (P < 0.05). This study presented a convenient and quantitative method to evaluate reflex excitability and muscle contraction dynamics. With proper simplifications, it can potentially be used for quantitative diagnosis and outcome evaluations of hyperreflexia in clinical settings. PMID:25654084

  4. Dopamine agonists suppress visual-cortical reflex myoclonus.

    PubMed Central

    Obeso, J A; Artieda, J; Tuñón, T; Luquin, M R; Martínez Lage, J M

    1985-01-01

    Two patients with a diagnosis of olivo-ponto-cerebellar atrophy developed cortical reflex myoclonus to visual (flash) and somaesthetic stimuli. Oral treatment with levodopacarbidopa (1000/100 mg) or subcutaneous administration of apomorphine (1 mg) abolished the visually-triggered myoclonus, without modifying reflex myoclonus to electrical or tactile stimulation. Intravenous administration of lisuride (0.1 mg) produced a marked reduction in both types of reflex myoclonus. These results indicate a selective inhibitory effect of dopamine agonist drugs on visual reflex myoclonus of cortical origin. Images PMID:3936901

  5. 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.

  6. 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

  7. Re-examination of the role of the human acoustic stapedius reflex

    NASA Astrophysics Data System (ADS)

    Phillips, Dennis P.; Stuart, Andrew; Carpenter, Michael

    2002-05-01

    The ``rollover'' seen in the word recognition performance scores of patients with Bell's palsy (facial nerve paralysis) has historically been taken as an indicator of the role of the stapedius reflex in the protection from upward spread of masking. Bell's palsy, however, may be a polyneuropathy, so it is not clear that the poor word recognition performance at high levels is necessarily attributable specifically to impaired facial nerve function. The present article reports two new experiments that probe whether an isolated impairment of the stapedius reflex can produce rollover in word recognition performance-intensity functions. In experiment 1, performance-intensity functions for monosyllabic speech materials were obtained from ten normal listeners under two listening conditions: normal and low-frequency augmented to offset the effects of the stapedius reflex on the transmission of low-frequency vibrations to the cochlea. There was no effect of the spectral augmentation on word recognition for stimulus levels up to 107 dB SPL. In experiment 2, six patients who had undergone stapedectomy were tested for rollover using performance-intensity functions. None of the patients showed rollover in their performance-intensity functions, even at stimulus levels in excess of 100 dB HL. These data suggest that if the stapedius reflex has a role in protection from upward spread of masking, then this role is inconsequential for word recognition in quiet.

  8. 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.

  9. Multi-MA reflex triode research.

    SciTech Connect

    Swanekamp, Stephen Brian; Commisso, Robert J.; Weber, Bruce V.; Riordan, John C.; Allen, Raymond J.; Goyer, John R.; Murphy, Donald P.; 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.

  10. Disturbed Paraspinal Reflex Following Prolonged Flexion-Relaxation and Recovery

    PubMed Central

    Rogers, Ellen L.; Granata, Kevin P.

    2006-01-01

    Study Design. Repeated measures experimental study of the effect of flexion-relaxation, recovery, and gender on paraspinal reflex dynamics. Objective. To determine the effect of prolonged flexion-relaxation and recovery time on reflex behavior in human subjects. Summary of Background Data. Prolonged spinal flexion has been shown to disturb the paraspinal reflex activity in both animals and human beings. Laxity in passive tissues of the spine from flexion strain may contribute to desensitization of mechanoreceptors. Animal studies indicate that recovery of reflexes may take up to several hours. Little is known about human paraspinal reflex behavior following flexion tasks or the recovery of reflex behavior following the flexion tasks. Methods. A total of 25 subjects performed static flexionrelaxation tasks. Paraspinal muscle reflexes were recorded before and immediately after flexion-relaxation and after a recovery period. Reflexes were quantified from systems identification analyses of electromyographic response in relation to pseudorandom force disturbances applied to the trunk. Results. Trunk angle measured during flexion-relaxation postures was significantly higher following static flexion-relaxation tasks (P < 0.001), indicating creep deformation of passive supporting structures in the trunk. Reflex response was diminished following flexion-relaxation (P < 0.029) and failed to recover to baseline levels during 16 minutes of recovery. Conclusion. Reduced reflex may indicate that the spine is less stable following prolonged flexion-relaxation and, therefore, susceptible to injury. The absence of recovery in reflex after a substantial time indicates that increased low back pain risk from flexion-relaxation may persist after the end of the flexion task. PMID:16582860

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

    PubMed

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

    2015-01-01

    Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD) and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1), where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. (1). Which cowgirl did Mary expect to have injured herself due to negligence? Four eye-tracking text-reading experiments were conducted on examples like (1), differing in whether the embedded clause was non-finite (1 and 3) or finite (2 and 4), and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2) or the wh-dependency was associated with a position earlier in the sentence (3 and 4). The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Experiments 3 and 4), wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure. PMID:26500579

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

    PubMed Central

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

    2015-01-01

    Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD) and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1), where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. (1). Which cowgirl did Mary expect to have injured herself due to negligence? Four eye-tracking text-reading experiments were conducted on examples like (1), differing in whether the embedded clause was non-finite (1 and 3) or finite (2 and 4), and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2) or the wh-dependency was associated with a position earlier in the sentence (3 and 4). The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Experiments 3 and 4), wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure. PMID:26500579

  13. Cough reflex sensitization from esophagus and nose.

    PubMed

    Hennel, Michal; Brozmanova, Mariana; Kollarik, Marian

    2015-12-01

    The diseases of the esophagus and nose are among the major factors contributing to chronic cough although their role in different patient populations is debated. Studies in animal models and in humans show that afferent C-fiber activators applied on esophageal or nasal mucosa do not initiate cough, but enhance cough induced by inhaled irritants. These results are consistent with the hypothesis that activation of esophageal and nasal C-fibers contribute to cough reflex hypersensitivity observed in chronic cough patients with gastroesophageal reflux disease (GERD) and chronic rhinitis, respectively. The afferent nerves mediating cough sensitization from the esophagus are probably the neural crest-derived vagal jugular C-fibers. In addition to their responsiveness to high concentration of acid typical for gastroesophageal reflux (pH < 5), esophageal C-fibers also express receptors for activation by weakly acidic reflux such as receptors highly sensitive to acid and receptors for bile acids. The nature of sensory pathways from the nose and their activators relevant for cough sensitization are less understood. Increased cough reflex sensitivity was also reported in many patients with GERD or rhinitis who do not complain of cough indicating that additional endogenous or exogenous factors may be required to develop chronic coughing in these diseases. PMID:26498387

  14. Reflex control of the circulation during exercise.

    PubMed

    Fadel, P J

    2015-12-01

    Appropriate cardiovascular and hemodynamic adjustments are necessary to meet the metabolic demands of working skeletal muscle during exercise. Alterations in the sympathetic and parasympathetic branches of the autonomic nervous system are fundamental in ensuring these adjustments are adequately made. Several neural mechanisms are responsible for the changes in autonomic activity with exercise and through complex interactions, contribute to the cardiovascular and hemodynamic changes in an intensity-dependent manner. This short review is from a presentation made at the Saltin Symposium June 2-4, 2015 in Copenhagen, Denmark. As such, the focus will be on reflex control of the circulation with an emphasis on the work of the late Dr. Bengt Saltin. Moreover, a concerted effort is made to highlight the novel and insightful concepts put forth by Dr. Saltin in his last published review article on the regulation of skeletal muscle blood flow in humans. Thus, the multiple roles played by adenosine triphosphate (ATP) including its ability to induce vasodilatation, override sympathetic vasoconstriction and stimulate skeletal muscle afferents (exercise pressor reflex) are discussed and a conceptual framework is set suggesting a major role of ATP in blood flow regulation during exercise. PMID:26589120

  15. Central and peripheral mechanisms underlying gastric distention inhibitory reflex responses in hypercapnic-acidotic rats

    PubMed Central

    Hsiao, An-Fu; Longhurst, John C.

    2011-01-01

    We have observed that in chloralose-anesthetized animals, gastric distension (GD) typically increases blood pressure (BP) under normoxic normocapnic conditions. However, we recently noted repeatable decreases in BP and heart rate (HR) in hypercapnic-acidotic rats in response to GD. The neural pathways, central processing, and autonomic effector mechanisms involved in this cardiovascular reflex response are unknown. We hypothesized that GD-induced decrease in BP and HR reflex responses are mediated during both withdrawal of sympathetic tone and increased parasympathetic activity, involving the rostral (rVLM) and caudal ventrolateral medulla (cVLM) and the nucleus ambiguus (NA). Rats anesthetized with ketamine and xylazine or ?-chloralose were ventilated and monitored for HR and BP changes. The extent of cardiovascular inhibition was related to the extent of hypercapnia and acidosis. Repeated GD with both anesthetics induced consistent falls in BP and HR. The hemodynamic inhibitory response was reduced after blockade of the celiac ganglia or the intraabdominal vagal nerves with lidocaine, suggesting that the decreased BP and HR responses were mediated by both sympathetic and parasympathetic afferents. Blockade of the NA decreased the bradycardia response. Microinjection of kainic acid into the cVLM reduced the inhibitory BP response, whereas depolarization blockade of the rVLM decreased both BP and HR inhibitory responses. Blockade of GABAA receptors in the rVLM also reduced the BP and HR reflex responses. Atropine methyl bromide completely blocked the reflex bradycardia, and atenolol blocked the negative chronotropic response. Finally, ?1-adrenergic blockade with prazosin reversed the depressor. Thus, in the setting of hypercapnic-acidosis, a sympathoinhibitory cardiovascular response is mediated, in part, by splanchnic nerves and is processed through the rVLM and cVLM. Additionally, a vagal excitatory reflex, which involves the NA, facilitates the GD-induced decreases in BP and HR responses. Efferent chronotropic responses involve both increased parasympathetic and reduced sympathetic activity, whereas the decrease in BP is mediated by reduced ?-adrenergic tone. PMID:21217073

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

    PubMed Central

    Liang, Jing Nong; Brown, David A.

    2015-01-01

    Objective Successful execution of upright locomotion requires coordinated interaction between controllers for locomotion and posture. Our earlier research supported this model in the non-impaired and found impaired interaction in the post-stroke nervous system during locomotion. In this study, we sought to examine the role of the Ia afferent spinal loop, via the H-reflex response, under postural influence during a locomotor task. We tested the hypothesis that the ability to increase stretch reflex gain in response to postural loads during locomotion would be reduced post-stroke. Methods Fifteen individuals with chronic post-stroke hemiparesis and 13 non-impaired controls pedaled on a motorized cycle ergometer with specialized backboard support system under (1) seated supported, and (2) non-seated postural-loaded conditions, generating matched pedal force outputs of two levels. H-reflexes were elicited at 90°crank angle. Results We observed increased H-reflex gain with postural influence in non-impaired individuals, but a lack of increase in individuals post-stroke. Furthermore, we observed decreased H-reflex gain at higher postural loads in the stroke-impaired group. Conclusion These findings suggest an impaired Ia afferent pathway potentially underlies the defects in the interaction between postural and locomotor control post-stroke and may explain reduced ability of paretic limb support during locomotor weight-bearing in individuals post-stroke. Significance These results support the judicious use of bodyweight support training when first helping individuals post-stroke to regain locomotor pattern generation and weight-bearing capability. PMID:26629996

  17. 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…

  18. Reflexivity in Teams: A Review and New Perspectives.

    PubMed

    Konradt, Udo; Otte, Kai-Philip; Schippers, Michaéla C; Steenfatt, Corinna

    2016-02-17

    Team reflexivity posits that the extent to which teams reflect upon and adapt their functioning is positively related to team performance. While remarkable progress has been made to provide evidence of this relationship, the underlying framework is missing elements of current theoretical streams for analyzing and describing teamwork, leaving the diversity of effects of team reflexivity often untouched. In this article, we present an update for this framework, by reviewing previous research on reflexivity, addressing gaps in the literature, and revising the original model by integrating feedback and dynamic team effectiveness frameworks for describing temporal developments of reflexivity. We furthermore propose a new dimensional structure for reflexivity, relying on prior work conceptualizing teams as information-processing systems that learn and advance through social-cognitive elements. Our model is therefore not only suitable for explaining the diverse set of relationships between team reflexivity on outcomes, but also provides valuable directions for viewing reflexivity as process that takes place during both transition and action phases of teamwork. We conclude with implications for managers, identify limitations, and propose an agenda for further research into this area. This article contributes an extended perspective relevant for further theory development and for effectively managing reflexivity in teams. PMID:26457836

  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. 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…

  1. A Movement Account of Long-Distance Reflexives

    ERIC Educational Resources Information Center

    McKeown, Rebecca Katherine

    2013-01-01

    This thesis examines reflexive pronouns, such as Icelandic "sig" (Cf. Thrainsson 2007), which may be bound from outside of an infinitive clause (which I call MD "medium distance" binding) in addition to being bound locally. I propose that such reflexives are linked to their antecedents via sisterhood followed by movement: the…

  2. 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…

  3. 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...

  4. Ethnic differences in the nociceptive flexion reflex (NFR)

    PubMed Central

    Campbell, Claudia M.; France, Christopher R.; Robinson, Michael E.; Logan, Henrietta L.; Geffken, Gary R.; Fillingim, Roger B.

    2009-01-01

    A substantial body of literature suggests that the experience of both clinical and experimental pain differs among ethnic groups, with African Americans generally reporting greater sensitivity to chronic and experimentally induced pain when compared to non-Hispanic whites. However, no studies to date have examined nociceptive processes that may underlie these differences. The nociceptive flexion reflex (NFR) is based on the measurement of stimulus-induced spinal reflexes. Prior research suggests that the NFR threshold, or RIII response, is highly correlated with subjective pain thresholds. The current study evaluated responses to the nociceptive flexion reflex in healthy young adults from two different ethnic groups: African Americans (n = 29) and non-Hispanic whites (n = 28). Perceptual responses (e.g., pain ratings) as well as physiological reflex responses (i.e., biceps femoris EMG) were assessed. Significant ethnic group differences were observed for NFR reflex threshold, with African Americans producing a reflex at lower stimulation intensities relative to non-Hispanic whites. Interestingly, verbal pain ratings at NFR threshold were not significantly different between the groups, suggesting that the lower stimulation intensities required to elicit a reflex in African–American versus non-Hispanic white participants were nonetheless perceived as similar. Psychological Involvement, Positive and Negative Mood, and Rumination were correlated with NFR threshold in a pattern that was consistent across both ethnic groups. These results extend previous research on ethnic differences in self-report measures of pain by demonstrating group differences in a nociceptive muscle reflex. PMID:17482362

  5. Role of stretch reflex in voluntary movements. [of human foot

    NASA Technical Reports Server (NTRS)

    Gottlieb, G. L.; Agarwal, G. C.

    1975-01-01

    The stretch reflex is often described as a spinal servomechanism, a device for assisting in the regulation of muscle length. Observation of the EMG response to mechanical interruption of voluntary movements fails to demonstrate a significant role for spinal reflexes at 40 msec latency. Two functional responses with latencies of 120 msec and 200 msec, implying supraspinal mediation, are observed.

  6. 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…

  7. Bidirectional interactions between the baroreceptor reflex and arousal: an update.

    PubMed

    Silvani, Alessandro; Calandra-Buonaura, Giovanna; Benarroch, Eduardo E; Dampney, Roger A L; Cortelli, Pietro

    2015-02-01

    Studies involving genetic engineering on animal models and mathematical analysis of cardiovascular signals on humans are shedding new light on the interactions between the arterial baroreceptor reflex (baroreflex) and arousal. Baroreceptor stimulation, if very mild or performed under anaesthesia, may inhibit cortical arousal. However, substantial increases or decreases in baroreflex activation cause arousal in animal models and human subjects in physiological conditions. On the other hand, cardiovascular changes during autonomic arousals and between the states of wakefulness and sleep involve changes in the baroreflex set point and balance with central autonomic commands. Neural connectivity and functional data suggest that the nucleus of the solitary tract, adrenergic C1 neurons of the medulla, and the parabrachial nucleus of the pons mediate the bidirectional interactions between the baroreflex and arousal. These interactions may constitute a positive feedback loop that facilitates sharp and coordinated brain state and autonomic transitions upon arousal: upon arousal, central autonomic commands may increase blood pressure, thereby loading baroreceptors and further increasing arousal. Anomalies of this feedback loop may play a role in the pathophysiology of disease conditions associated with cardiovascular and sleep-wake cycle alterations. These conditions include: obstructive sleep apnoea syndrome, with its association with excessive daytime sleepiness and baroreflex impairment; and insomnia, with its association with autonomic hyperarousal and hypertension. When faced with disorders associated with cardiovascular and sleep-wake cycle alterations, clinical reasoning should entertain the possibility that both conditions are strongly influenced by anomalies of baroreflex function. PMID:25616389

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

    PubMed Central

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

    2015-01-01

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

  9. Resuscitation and auto resuscitation by airway reflexes in animals

    PubMed Central

    2013-01-01

    Various diseases often result in decompensation requiring resuscitation. In infants moderate hypoxia evokes a compensatory augmented breath – sigh and more severe hypoxia results in a solitary gasp. Progressive asphyxia provokes gasping respiration saving the healthy infant – autoresuscitation by gasping. A neonate with sudden infant death syndrome, however, usually will not survive. Our systematic research in animals indicated that airway reflexes have similar resuscitation potential as gasping respiration. Nasopharyngeal stimulation in cats and most mammals evokes the aspiration reflex, characterized by spasmodic inspiration followed by passive expiration. On the contrary, expiration reflex from the larynx, or cough reflex from the pharynx and lower airways manifest by a forced expiration, which in cough is preceded by deep inspiration. These reflexes of distinct character activate the brainstem rhythm generators for inspiration and expiration strongly, but differently. They secondarily modulate the control mechanisms of various vital functions of the organism. During severe asphyxia the progressive respiratory insufficiency may induce a life-threatening cardio-respiratory failure. The sniff- and gasp-like aspiration reflex and similar spasmodic inspirations, accompanied by strong sympatho-adrenergic activation, can interrupt a severe asphyxia and reverse the developing dangerous cardiovascular and vasomotor dysfunctions, threatening with imminent loss of consciousness and death. During progressive asphyxia the reversal of gradually developing bradycardia and excessive hypotension by airway reflexes starts with reflex tachycardia and vasoconstriction, resulting in prompt hypertensive reaction, followed by renewal of cortical activity and gradual normalization of breathing. A combination of the aspiration reflex supporting venous return and the expiration or cough reflex increasing the cerebral perfusion by strong expirations, provides a powerful resuscitation and autoresuscitation potential, proved in animal experiments. They represent a simple but unique model tested in animal experiments. PMID:23968541

  10. The nociceptive withdrawal reflex does not adapt to joint position change and short-term motor practice.

    PubMed

    Eckert, Nathan; Riley, Zachary A

    2013-01-01

    The nociceptive withdrawal reflex is a protective mechanism to mediate interactions within a potentially dangerous environment. The reflex is formed by action-based sensory encoding during the early post-natal developmental period, and it is unknown if the protective motor function of the nociceptive withdrawal reflex in the human upper-limb is adaptable based on the configuration of the arm or if it can be modified by short-term practice of a similar or opposing motor action. In the present study, nociceptive withdrawal reflexes were evoked by a brief train of electrical stimuli applied to digit II, 1) in five different static arm positions and, 2) before and after motor practice that was opposite (EXT) or similar (FLEX) to the stereotyped withdrawal response, in 10 individuals. Withdrawal responses were quantified by the electromyography (EMG) reflex response in several upper limb muscles, and by the forces and moments recorded at the wrist. EMG onset latencies and response amplitudes were not significantly different across the arm positions or between the EXT and FLEX practice conditions, and the general direction of the withdrawal response was similar across arm positions. In addition, the force vectors were not different after practice in either the practice condition or between EXT and FLEX conditions. We conclude the withdrawal response is insensitive to changes in elbow or shoulder joint angles as well as remaining resistant to short-term adaptations from the practice of motor actions, resulting in a generalized limb withdrawal in each case. It is further hypothesized that the multisensory feedback is weighted differently in each arm position, but integrated to achieve a similar withdrawal response to safeguard against erroneous motor responses that could cause further harm. The results remain consistent with the concept that nociceptive withdrawal reflexes are shaped through long-term and not short-term action based sensory encoding. PMID:24555075

  11. REFLEX, a social-cognitive group treatment to improve insight in schizophrenia: study protocol of a multi-center RCT

    PubMed Central

    2011-01-01

    Background Insight is impaired in a majority of people with schizophrenia. Impaired insight is associated with poorer outcomes of the disorder. Based on existing literature, we developed a model that explains which processes may possibly play a role in impaired insight. This model was the starting point of the development of REFLEX: a brief psychosocial intervention to improve insight in schizophrenia. REFLEX is a 12-sessions group training, consisting of three modules of four sessions each. Modules in this intervention are: "coping with stigma", "you and your personal narrative", and "you in the present". Methods/Design REFLEX is currently evaluated in a multicenter randomized controlled trial. Eight mental health institutions in the Netherlands participate in this evaluation. Patients are randomly assigned to either REFLEX or an active control condition, existing of cognitive remediation exercises in a group. In a subgroup of patients, fMRI scans are made before and after training in order to assess potential haemodynamic changes associated with the effects of the training. Discussion REFLEX is one of the few interventions aiming specifically to improving insight in schizophrenia and has potential value for improving insight. Targeting insight in schizophrenia is a complex task, that comes with several methodological issues. These issues are addressed in the discussion of this paper. Trial registration Current Controlled Trials: ISRCTN50247539 PMID:21975132

  12. Focusing experiments with an inverse reflex tetrode

    SciTech Connect

    Pershing, D.E.; Golden, J.; Pasour, J.A.; Kapetanakos, C.A.

    1982-05-01

    The focusing properties of an Inverse Reflex Tetrode (IRT) used for ion beam generation have been investigated experimentally. Focusing is achieved by replacing the planar (0/sup 0/) electrodes of a standard IRT with moderately inwardly tapered electrodes (7.5, 10, and 15/sup 0/). The greatest degree of focusing is obtained with the 15/sup 0/ electrodes as determined by beam profile measurements using streak photography and nuclear activation techniques at various axial target positions. A scissoring effect is observed, due to temporal variations in generator voltage and current, that is manifested by an axial variation in the focal point with time. Calculations of proton trajectories confirm the experimental results and demonstrate the importance of self-fields within the A-K gap in determining the characteristics of an ion beam generated by an IRT.

  13. Bremsstrahlung target optimization for reflex triodes

    SciTech Connect

    Swanekamp, S. B.; Weber, B. V.; Stephanakis, S. J.; Mosher, D.; Commisso, R. J.

    2008-08-15

    The anode (tantalum) foil thickness in a reflex triode was varied from 2.5 to 250 {mu}m to maximize the dose from bremsstrahlung produced by a 1 MV, 1 MA, 100 ns electron beam. Experiments and computer simulations show that the dose is maximized for a foil thickness of about 25 {mu}m, 1/18th of the electron range computed from the continuous slowing down approximation. For foils thicker than optimum, self-absorption in the foil attenuates 10-100 keV photons, reducing the dose. For foils thinner than optimum, the dose decreases as a result of electron migration to large radius. A simple formula that predicts the optimum thickness as a function of the beam current and voltage is derived that should be applicable to a large range of experimental parameters.

  14. Modeling of deep breath vasoconstriction reflex.

    PubMed

    Chalacheva, Patjanaporn; Khoo, Michael C K

    2015-08-01

    Deep breaths akin to sighs have been reported to cause peripheral vasoconstriction. Our previous simulation studies have shown that this phenomenon cannot be reproduced in existing circulatory control models without inclusion of a respiratory-vascular coupling mechanism. To better understand this "sigh-vasoconstriction reflex", we investigated the effect of spontaneous and passively induced sighs as well as spontaneous breathing on peripheral vasoconstriction during wakefulness and non-rapid eye movement sleep in human subjects. We found that both spontaneous and induced sighs caused vasoconstriction during wakefulness and sleep. The coupling between respiration and vasoconstriction is also present even in an absence of deep breaths. The coupling mechanism is largely linear with increased nonlinearity during induced sighs. Since peripheral vascular resistance modulation is known to be sympathetically mediated, investigation of this coupling could potentially allow us to assess sympathetic function through non-invasive measurements and simple interventions. PMID:26738099

  15. Ultrasound treatment of reflex sympathetic dystrophy.

    PubMed

    Portwood, M M; Lieberman, J S; Taylor, R G

    1987-02-01

    Three cases of lower extremity reflex sympathetic dystrophy (RSD) responded dramatically to a daily low dose ultrasound (0.5 watts/cm2 X 5 minutes) therapy to the tarsal tunnel and plantar nerve distribution, and the use of a shoe insert. Two of the three cases had been refractory to more standard therapy for RSD, including pharmacologic agents. All three patients preferred a conservative approach to surgical sympathectomy. No complications were observed, and all three cases are now symptom free. Daily ultrasound treatments are time-consuming and costly but are safe and may be useful for patients who refuse surgical sympathectomy. We hypothesize that ultrasound may have affected peripheral sympathetic nerve fibers. However, more indirect effects of ultrasound, such as increased blood flow to the limb, may be part of the action mechanism as well. PMID:3813857

  16. The Chinchilla's vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Merwin, W. H., Jr.; Wall, Conrad, III; Tomko, D. L.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) was measured and characterized in seven adult chinchillas using 0.01 to 1.0 Hz angular velocity sinusoids. Gains were less than compensatory, and were variable from day to day, but phases were highly repeatable both within and between animals. The best fitting transfer function to the average data of all animals had a dominant time constant of 7.5 sec, and an adaptation operator with a time constant of 24.0 sec. There were certain nonlinearities in the horizontal VOR of this animal, and it was difficult to elicit a robust optokinetic response. Results are discussed in relation to similar measurements in other species.

  17. Vestibulospinal reflexes as a function of microgravity

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  18. Did reflexive catalysts drive chemical evolution?

    NASA Astrophysics Data System (ADS)

    Allen, Gordon

    1994-02-01

    High-energy starting materials and energy sources on the primitive earth would have generated abundant and varied organic molecules of small or medium size. It is questionable, however, whether ordinary chemical evolution could have produced information-carrying polymers. The end point might have been a fixed steady state if some form of autocatalysis had not intervened. Autocatalytic synthesis is possible for small molecules as illustrated by the formose reaction, in which glycolaldehyde condenses with formaldehyde to form sugars, and resulting tetroses may cleave into two molecules of glycolaldehyde. This and other ‘reflexive catalysts’, some functioning in molecular aggregates, may have energized chemical evolution and carried it to a level at which RNA or an RNA analog could replicate itself.

  19. 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.

  20. The oculocardiac reflex in aponeurotic blepharoptosis surgery.

    PubMed

    Uda, Hirokazu; Sugawara, Yasusih; Sarukawa, Syunji; Sunaga, Ataru

    2014-06-01

    The purpose of this study was to investigate the correlation between the oculocardiac reflex (OCR) and blepharoptosis surgery for safe eyelid surgery. Fifty-four consecutive patients with bilateral aponeurotic blepharoptosis were enrolled in this study. Changes in electrocardiography (ECG) monitoring were recorded during surgery. Preoperative pressing on the globe and intraoperative stretching of the levator aponeurosis were also carried out and the occurrence rate of the OCR was recorded. A positive OCR was observed in 12 patients (22.2%) in the preoperative globe-pressing test, whereas a positive OCR was observed in 22 patients (40.7%) in the levator-stretching test. The levator-stretching test did not indicate a significant difference in the rate of heart rate decrease with respect to laterality. No correlation was observed between age and the occurrence of OCR. On the other hand, there was a significant difference in the percentage of heart rate decrease between patients with positive OCR and negative OCR as determined in the globe-pressing test (mean = 13.1% vs. 5.4%). During the practical operative manoeuvre, no bradycardia was observed in any case. This study confirmed that a rapid and strong traction of levator aponeurosis induces the OCR regardless of laterality and age. Atraumatic and gentle handling are essential to prevent OCR. The preoperative globe-pressing test may be an index of the OCR in reflex-prone patients. Intraoperative ECG monitoring will be useful for early onset detection, although positive OCR was not observed in any patient during the practical surgical manoeuvre. PMID:24828860

  1. Fusimotor reflexes in triceps surae elicited by natural stimulation of muscle afferents from the cat ipsilateral hind limb

    PubMed Central

    Appelberg, B.; Hulliger, M.; Johansson, H.; Sojka, P.

    1982-01-01

    1. Experiments were performed in forty-one cats anaesthetized with chloralose. 2. The aim of the study was to investigate whether activity in stretch-sensitive muscle receptors may cause reflex effects in fusimotor neurones. 3. Activity in fusimotor neurones was studied indirectly by recording from primary and secondary muscle spindle afferents of the triceps surae muscle. The mean rate of firing of the afferents as well as either dynamic index (during ramp extension) or modulation (during sinusoidal extension) was determined. This was done under control conditions, with the posterior biceps—semitendinosus muscles relaxed, and under test conditions, with the same muscles extended. 4. All together, seventy-one primary afferents were studied quantitatively. Pure or predominantly dynamic effects were observed in twenty-two, pure or predominantly static effects in nine and no statistically significant effects in forty of the units. Amongst seven secondary afferents studied, two showed weak fusimotor activation, the other five were not influenced. 5. Electrical stimulation of the posterior biceps—semitendinosus or medial gastrocnemius nerves at group II strength was observed to cause dynamic fusimotor reflexes on a number of occasions. 6. The reflex effects observed were, on many occasions, recorded in spinalized preparations. 7. The reflex effects were not accompanied by any detectable e.m.g. activity in triceps, as judged from surface e.m.g. recordings. The reflex effects observed are therefore tentatively ascribed to activation of ?-motoneurones, yet a contribution from ?-motoneurones cannot wholly be excluded. 8. On the basis of available evidence concerning reflex connexions to ?-motoneurones from various muscle afferents, it is suggested that the effects observed were caused by activation of muscle spindle secondary endings. PMID:6216334

  2. The effects of transcranial magnetic stimulation on vibratory-induced presynaptic inhibition of the soleus H reflex.

    PubMed

    Guzmán-López, Jessica; Costa, João; Selvi, Aikaterini; Barraza, Gonzalo; Casanova-Molla, Jordi; Valls-Solé, Josep

    2012-08-01

    A single-pulse transcranial magnetic stimulus (TMS) may induce contraction in many muscles of the body at the same time. This is specially the case when using the double-cone coil to obtain the motor evoked potentials in leg muscles. Even if intensity is kept below threshold for the soleus muscle, TMS induces facilitation of the soleus H reflex that is separated into two phases: the first, peaking at 10-20 ms and the second, peaking at 70-90 ms. We investigated the possibility that TMS-induced facilitation of the H reflex was related, at least in part, to the reafferentation volley reaching the alpha motoneuron after synchronized contraction of other muscles in the body. To test this hypothesis, we examined the effects of vibration on the TMS-induced facilitation of the soleus H reflex. As expected, vibration applied over the triceps tendon caused a significant reduction in H reflex amplitude: 42.4 ± 6.4 % of control values. When conditioned by TMS at intervals corresponding to the first phase, the H reflex was facilitated to the same extent in both conditions: with and without vibration. However, at intervals corresponding to the second facilitation phase, there was a significantly reduced facilitation with vibration. These differential effects of vibration on the two phases of the TMS-induced facilitation of the H reflex indicate a different mechanism for each facilitation phase. The first phase could result from direct corticospinal excitatory input, while the second phase might depend on inputs via Ia afferents from heteronymous muscles. PMID:22644238

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

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.

    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.

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

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.; Weber, B.V.

    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.

  5. Report on a membership audit of the Association of Chartered Physiotherapists in Reflex Therapy (ACPIRT).

    PubMed

    Berry, Gunnel; Svarovska, Beth

    2014-08-01

    Reflex Therapy (RT), akin to reflexology, is a non-invasive physiotherapy modality approved by the UK Chartered Society of Physiotherapists. One hundred members of the Association of Chartered Physiotherapists in Reflex Therapy (ACPIRT) participated in an audit to establish a baseline of practice. Findings indicate that experienced therapists use RT in conjunction with their professional skills to induce relaxation (95%) and reduce pain (86%) for patients with conditions including whiplash injury and chronic pain. According to 68% of respondents, RT is "very good," "good" or "as good as" orthodox physiotherapy practices. Requiring minimal equipment, RT may be as cost effective as orthodox physiotherapy with regards to duration and frequency of treatment. PMID:25129885

  6. 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.

  7. The effects of neural synchronization and peripheral compression on the acoustic-reflex threshold

    NASA Astrophysics Data System (ADS)

    Müller-Wehlau, Matthias; Mauermann, Manfred; Dau, Torsten; Kollmeier, Birger

    2005-05-01

    This study investigates the acoustic reflex threshold (ART) dependency on stimulus phase utilizing low-level reflex audiometry [Neumann et al., Audiol. Neuro-Otol. 1, 359-369 (1996)]. The goal is to obtain optimal broadband stimuli for elicitation of the acoustic reflex and to obtain objective determinations of cochlear hearing loss. Three types of tone complexes with different phase characteristics were investigated: A stimulus that compensates for basilar-membrane dispersion, thus causing a large overall neural synchrony (basilar-membrane tone complex-BMTC), the temporally inversed stimulus (iBMTC), and random-phase tone complexes (rTC). The ARTs were measured in eight normal-hearing and six hearing-impaired subjects. Five different conditions of peak amplitude and stimulus repetition rate were used for each stimulus type. The results of the present study suggest that the ART is influenced by at least two different factors: (a) the degree of synchrony of neural activity across frequency, and (b) the fast-acting compression mechanism in the cochlea that is reduced in the case of a sensorineural hearing loss. The results allow a clear distinction of the two subjects groups based on the different ART for the utilized types and conditions of the stimuli. These differences might be useful for objective recruitment detection in clinical diagnostics. .

  8. Ivane S. Beritashvili (1884-1974): from spinal cord reflexes to image-driven behavior.

    PubMed

    Tsagareli, M G; Doty, R W

    2009-10-20

    Ivane Beritashvili ("Beritoff" in Russian, and often in Western languages) was a major figure in 20th-century neuroscience. Mastering the string galvanometer, he founded the electrophysiology of spinal cord reflexes, showing that inhibition is a distinctly different process from excitation, contrary to the concepts of his famous mentor, Wedensky. Work on postural reflexes with Magnus was cut short by World War I, but he later demonstrated that navigation in two-dimensional space without vision is a function solely of the vestibular system rather than of muscle proprioception. Persevering in his experiments despite postwar turmoil he founded an enduring Physiology Institute in Tbilisi, where he pursued an ingenious and extensive investigation of comparative memory in vertebrates. This revealed the unique nature of mammalian memory processes, which he forthrightly called "image driven," and distinguished them unequivocally from those underlying conditional reflexes. For some 30 years the Stalinist terror confined his publications to the Russian language. Work with his colleague, Chichinadze, discovering that memory confined to one cerebral hemisphere could be accessed by the other via a specific forebrain commissure, did reach the West, and ultimately led to recognition of the fascinating "split brain" condition. In the 1950s he was removed from his professorial position for 5 years as being "anti-Pavlovian." Restored to favor, he was honorary president of the "Moscow Colloquium" that saw the foundation of the International Brain Research Organization. PMID:19589370

  9. Honey intoxication and the Bezold-Jarisch reflex.

    PubMed

    Eller, Philipp; Hochegger, Kathrin

    2010-10-01

    Food-poisonings with grayanotoxin-contaminated honey can induce atrioventricular blocks. Actually, grayanotoxin and similar neurotoxins like veratridine stimulate the unmyelinated afferent cardiac branches of the vagus nerve. Tonic inhibition of central vasomotor centres leads to a reduced sympathetic output and a reduced peripheral vascular resistance with bradycardia, continued hypotension, and peripheral vasodilation. This cardioinhibitory reflex is known as the Bezold-Jarisch reflex. Recognition of the Bezold-Jarisch reflex is important, as there is no need for electric pacing, when atrioventricular blocks occur. The pharmacologically induced bradycardia and heart blocks do promptly disappear after injection of the antidote atropine. PMID:19176253

  10. Maturation of bladder reflex pathways during postnatal development.

    PubMed

    de Groat, W C; Araki, I

    1999-01-01

    Neuroanatomical and electrophysiological techniques have provided new insights into the organization of the spinal cord circuitry and the neurotransmitter mechanisms involved in primitive voiding reflexes in neonatal animals. In addition, studies of unitary synaptic transmission in spinal cord slice preparations indicate that developmental and spinal cord injury induced plasticity in sacral parasympathetic reflex pathways is due in part to alterations in 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:10599429

  11. Dissociated vertical divergence: a righting reflex gone wrong.

    PubMed

    Brodsky, M C

    1999-09-01

    Dissociated vertical divergence (DVD) is an ocular motor disorder characterized by a slow, upward drift of 1 eye when the other eye is fixating a target. I propose that DVD is a dorsal light reflex in which asymmetrical visual input to the 2 eyes evokes a vertical divergence movement of the eyes. This primitive visuo-vestibular reflex functions as a righting response to restore vertical orientation in lower lateral-eyed animals by equalizing binocular visual input. The dorsal light reflex is suppressed in humans but can manifest as DVD when early-onset strabismus precludes normal binocular development. PMID:10496394

  12. 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

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

    ERIC Educational Resources Information Center

    Taylor, Myra; Houghton, Stephen; Chapman, Elaine

    2004-01-01

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

  14. Role of small diameter afferents in reflex inhibition during human muscle fatigue.

    PubMed Central

    Garland, S J

    1991-01-01

    1. Previous work has shown that the H reflex excitability of the human soleus motoneurones is reduced during fatigue and is accompanied by a corresponding decrease in electromyographic (EMG) activity during maximal voluntary contractions. These findings were consistent with the existence of a reflex whereby alpha-motoneurones are inhibited by sensory input from the fatigued muscle. 2. To elucidate the contribution of different-sized afferents in such reflex inhibition, compression of the sciatic nerve was used in an attempt to block large myelinated afferents prior to fatigue. 3. Fatigue of the soleus muscle was induced under ischaemic conditions by intermittent electrical stimulation at 15 Hz in ten healthy subjects. These subjects also participated in a control test in which the compression block was followed by ischaemia without fatigue. 4. Following nerve compression alone, both the mean maximal plantarflexion torque and the associated EMG for all ten subjects declined by 18.8 +/- 16.2% (S.D.) and 13.4 +/- 17.2%, respectively. 5. Following fatigue, there were five subjects in whom the large afferents remained blocked and the experimental findings were consistent with the existence of reflex inhibition during fatigue. The mean maximal plantarflexion torque decreased further by 36.2 +/- 7.6% from the value following the compression block compared to a decrease of 5.0 +/- 9.9% in the ischaemia control. The mean EMG associated with these contractions also decreased from post-block values by 56.8 +/- 19.6% following fatigue and by only 6.4 +/- 8.0% following ischaemia alone. 6. The peripheral excitability of the neuromuscular junction and muscle fibre membrane was adequate following fatigue as evidenced by only modest changes in the M wave (muscle compound action potential). The descending motor drive was deemed sufficient because of the absence of any large interpolated twitches superimposed upon the maximal voluntary contraction in all but two subjects. 7. The declines in maximal plantarflexion torque and the associated EMG activity were very similar to those found in a previous study in which the sensory input was unaltered. The findings demonstrated that any reflex inhibition of the alpha-motoneurone pool during fatigue was probably not mediated by large diameter afferents. Rather, it is suggested that the reflex is mediated by smaller diameter afferents originating from the fatigued muscle. PMID:1770449

  15. Modulation of postural reflexes by voluntary movement1

    PubMed Central

    Gottlieb, Gerald L.; Agarwal, Gyan C.

    1973-01-01

    We have observed that there is a brief, 400 msec period of widespread facilitation of both the Hoffmann and the tendon-jerk reflexes associated with the initiation of a variety of local, voluntary, isometric efforts. It is suggested that the site of this facilitation lies within the spinal cord. We have also observed that this period is followed, for the Hoffmann reflex, by a period of spinal inhibition. By contrast, the tendon-jerk is facilitated, at a reduced level, for at least another 500 msec by mechanisms probably working at the muscle spindle. These results are discussed in comparison with experiments involving activation of the reflex agonist and antagonist muscles. It is proposed that voluntary control of the locomotor system is organized through separate mechanisms for muscle recruitment and for regulation of the sensitivity of the myotatic reflex loop. PMID:4354398

  16. 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...

  17. Spinal Reflexes During Postural Control Under Psychological Pressure.

    PubMed

    Tanaka, Yoshifumi

    2015-07-01

    This study investigated the effect of psychological pressure on spinal reflex excitability. Thirteen participants performed a balancing task by standing on a balance disk with one foot. After six practice trials, they performed one nonpressure and one pressure trial involving a performance-contingent cash reward or punishment. Stress responses were successfully induced; state anxiety, mental effort, and heart rates all increased under pressure. Soleus Hoffmann reflex amplitude in the pressure trial was significantly smaller than in the nonpressure trial. This modification of spinal reflexes may be caused by presynaptic inhibition under the control of higher central nerve excitation under pressure. This change did not prevent 12 of the 13 participants from successfully completing the postural control task under pressure. These results suggest that Hoffmann reflex inhibition would contribute to optimal postural control under stressful situations. PMID:25587695

  18. Nasal Reflexes: Implications for Exercise, Breathing, and Sex

    PubMed Central

    Baraniuk, James N.; Merck, Samantha J.

    2014-01-01

    Nasal patency, with both congestion and decongestion, is affected in a wide variety of reflexes. Stimuli that lead to nasal reflexes include exercise, alterations of body position, pressure, and temperature, neurological syndromes, and dentists. As anticipated, the vagal and trigeminal systems are closely integrated through nasobronchial and bronchonasal reflexes. However, perhaps of greater pathophysiological importance are the naso-hypopharyngea-laryngeal reflexes that become aggravated during sinusitis. None other than Sigmund Freud saw deeply beyond the facial adornment and recognized the deeper sexual tensions that can regulate nasal functions and psychoanalytical status. Wine, women and song are linked with airflow through the nose, the nose, that by any other name would still smell as sweetly. PMID:18417057

  19. Critical Bandwidth and Sensitivity Prediction in the Acoustic Stapedial Reflex

    ERIC Educational Resources Information Center

    Schwartz, Daniel M.; Sanders, Jay W.

    1976-01-01

    Critical bandwidth measurements and sensitivity prediction from the acoustic reflex test results were obtained on 20 adult normal-hearing and two groups of 10 adult hearing impaired Ss each representing mild-to-moderate and severe hearing loss. (Author)

  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. Response characteristics of the human torsional vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.

    1992-01-01

    The characteristics of the response dynamics of the human torsional vestibuloocular reflex were studied during controlled rotations about an earth-horizontal axis. The results extended the frequency range to 2 Hz and identified the nonlinearity of the amplitude response.

  2. [Red reflex: prevention way to blindness in childhood].

    PubMed

    de Aguiar, Adriana Sousa Carvalho; Cardoso, Maria Vera Lúcia Moreira Leitão; Lúcio, Ingrid Martins Leite

    2007-01-01

    This study had as objective to investigate the result and the colour gradation of red reflex test in newborns (NB). It is a exploratory, quantitative study and the sample was 180 NB from maternity ward in Fortaleza-CE. From this, 156 showed result "no altered" and 24 "suspect". About the aspect of red reflex, 144 NB showed the same coloration in the two eyes, in 35 of this, the colour was red, in 33, orange reddish, in 46 orange colour, in 24 light yellow, in 6 yellow with whitish stains central. Of the suspect cases, the reflex was light yellow with whitish stains with lines. The nurse trained to accomplish the red reflex test can have important role at Neonatal Unit with actions about the prevention of ocular alterations in the childhood. PMID:18041554

  3. Reflexive Research Ethics in Fetal Tissue Xenotransplantation Research

    PubMed Central

    Panikkar, Bindu; Smith, Natasha; Brown, Phil

    2013-01-01

    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 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

  4. Speech Performance, Dysphagia and Oral Reflexes in Cerebral Palsy.

    ERIC Educational Resources Information Center

    Love, Russell J.; And Others

    1980-01-01

    The adequacy of biting, sucking, swallowing, and chewing as well as the presence or absence of nine infantile oral reflexes were assessed in 60 cerebral palsied individuals (ages 3 to 23). (Author/PHR)

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

    PubMed

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

    2015-04-01

    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

  6. 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.

  7. Cardiovascular Reflexes Activity and Their Interaction during Exercise

    PubMed Central

    Crisafulli, Antonio; Marongiu, Elisabetta; Ogoh, Shigehiko

    2015-01-01

    Cardiac output and arterial blood pressure increase during dynamic exercise notwithstanding the exercise-induced vasodilation due to functional sympatholysis. These cardiovascular adjustments are regulated in part by neural reflexes which operate to guarantee adequate oxygen supply and by-products washout of the exercising muscles. Moreover, they maintain adequate perfusion of the vital organs and prevent excessive increments in blood pressure. In this review, we briefly summarize neural reflexes operating during dynamic exercise with particular emphasis on their interaction. PMID:26557662

  8. 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

  9. Motor neurone responses during a postural reflex in solitarious and gregarious desert locusts.

    PubMed

    Blackburn, Laura M; Ott, Swidbert R; Matheson, Tom; Burrows, Malcolm; Rogers, Stephen M

    2010-08-01

    Desert locusts show extreme phenotypic plasticity and can change reversibly between two phases that differ radically in morphology, physiology and behaviour. Solitarious locusts are cryptic in appearance and behaviour, walking slowly with the body held close to the ground. Gregarious locusts are conspicuous in appearance and much more active, walking rapidly with the body held well above the ground. During walking, the excursion of the femoro-tibial (F-T) joint of the hind leg is smaller in solitarious locusts, and the joint is kept more flexed throughout an entire step. Under open loop conditions, the slow extensor tibiae (SETi) motor neurone of solitarious locusts shows strong tonic activity that increases at more extended F-T angles. SETi of gregarious locusts by contrast showed little tonic activity. Simulated flexion of the F-T joint elicits resistance reflexes in SETi in both phases, but regardless of the initial and final position of the leg, the spiking rate of SETi during these reflexes was twice as great in solitarious compared to gregarious locusts. This increased sensory-motor gain in the neuronal networks controlling postural reflexes in solitarious locusts may be linked to the occurrence of pronounced behavioural catalepsy in this phase similar to other cryptic insects such as stick insects. PMID:20416321

  10. 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.

  11. The dazzle reflex: electrophysiological signals from ocular muscles reveal strong binocular summation effects.

    PubMed

    Plainis, S; Murray, I J; Carden, D

    2006-05-01

    Under dark adapted or dim conditions the mammalian visual system is carefully programmed to respond rapidly to the sudden onset of bright lights. This response, called the dazzle reflex, is controlled from sub-cortical structures of the brain. It is known anecdotally that exposure to a bright light when dark adapted induces an instinctive closure of one eye to reduce the pain associated with dazzle. This binocular summation of the dazzle response has not previously been reported. The dazzle reflex can be measured in human subjects by recording the electrical activity from surface electrodes located near the muscles around the eye. In this paper we report an investigation of the apparent binocular summation of the dazzle reflex using this technique. The data reveal a clear difference between monocular and binocular stimulation, with the binocular response being much larger than the monocular response. Furthermore this monocular/binocular difference arises only if the stimulus duration is longer than approximately 1 s. These observations are interpreted in terms of the known physiology of blink mechanisms. PMID:16684158

  12. 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

  13. Additive Effects of Threat-of-Shock and Picture Valence on Startle Reflex Modulation

    PubMed Central

    Bublatzky, Florian; Guerra, Pedro M.; Pastor, M. Carmen; Schupp, Harald T.; Vila, Jaime

    2013-01-01

    The present study examined the effects of sustained anticipatory anxiety on the affective modulation of the eyeblink startle reflex. Towards this end, pleasant, neutral and unpleasant pictures were presented as a continuous stream during alternating threat-of-shock and safety periods, which were cued by colored picture frames. Orbicularis-EMG to auditory startle probes and electrodermal activity were recorded. Previous findings regarding affective picture valence and threat-of-shock modulation were replicated. Of main interest, anticipating aversive events and viewing affective pictures additively modulated defensive activation. Specifically, despite overall potentiated startle blink magnitude in threat-of-shock conditions, the startle reflex remained sensitive to hedonic picture valence. Finally, skin conductance level revealed sustained sympathetic activation throughout the entire experiment during threat- compared to safety-periods. Overall, defensive activation by physical threat appears to operate independently from reflex modulation by picture media. The present data confirms the importance of simultaneously manipulating phasic-fear and sustained-anxiety in studying both normal and abnormal anxiety. PMID:23342060

  14. ["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

  15. Impaired Sacculocollic Reflex in Lateral Medullary Infarction

    PubMed Central

    Kim, Seonhye; Kim, Hyo-Jung; Kim, Ji Soo

    2011-01-01

    Objective: The aim of this study was to determine saccular dysfunction by measuring cervical vestibular-evoked myogenic potentials (cVEMP) and to correlate abnormality of cVEMP with results of other vestibular function tests in lateral medullary infarction (LMI). Methods: We recorded cVEMP in 21 patients with LMI documented on MRI. cVEMP was induced by a short tone burst and was recorded in contracting sternocleidomastoid muscle while patients turned their heads forcefully to the contralateral side against resistance. Patients also underwent video-oculographic recording of spontaneous, gaze-evoked and head shaking nystagmus (HSN), evaluation of ocular tilt reaction (OTR), measurement of the subjective visual vertical (SVV) tilt, bithermal caloric tests, and audiometry. Results: Nine patients (43%) showed abnormal cVEMP, unilateral in seven and bilateral in two. The cVEMP abnormalities included decreased p13–n23 amplitude in four, delayed p13/n23 responses in five, and both decreased and delayed responses in two. The abnormal cVEMP was ipsilesional in five, contralesional in two, and bilateral in two. The prevalence of OTR/SVV tilt, spontaneous nystagmus, and HSN did not differ between the patients with normal and abnormal cVEMP. Conclusion: cVEMP was abnormal in approximately half of the patients with LMI. The abnormal cVEMP indicates damage to the descending sacculocollic reflex pathway or disruption of commissural modulation between the vestibular nuclei. PMID:21415908

  16. Sympathetic skin responses in reflex sympathetic dystrophy.

    PubMed

    Bolel, K; Hizmetli, S; Akyüz, A

    2006-07-01

    This study was performed to determine the utility of sympathetic skin response (SSR) in evaluating the sympathetic function and to follow up the effects of sympathetic blockade in reflex sympathetic dystrophy (RSD). Thirty patients having RSD with upper extremity involvement were randomly divided into two groups. Besides medical therapy and exercise, physical therapy agents were applied to both the groups. In addition to this treatment protocol, stellar ganglion blockade was done by diadynamic current in Group II. The normal sides of the patients were used for the control group. SSRs were measured in all the patients before and after the therapy. The amplitude was found to be increased and the latency was found to be decreased in the affected side in both the groups before the therapy. After the therapy, the amplitude was decreased and latency was increased in both the groups. But, the differences in amplitude (P = 0.001) and latency (P = 0.002) before and after the therapy were significantly higher in Group II. (Before the treatment, SSRs were significantly different between the normal and the affected sides in both the groups. The observed change in SSRs after the treatment was higher in Group II.) It was concluded that, SSR can be a useful and noninvasive method in diagnosing the sympathetic dysfunction in RSD and can be used for evaluating the response to sympathetic blockade and other treatment modalities. PMID:16328419

  17. 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.

  18. Artificial balancer - supporting device for postural reflex.

    PubMed

    Wojtara, Tytus; Sasaki, Makoto; Konosu, Hitoshi; Yamashita, Masashi; Shimoda, Shingo; Alnajjar, Fady; Kimura, Hidenori

    2012-02-01

    The evolutionarily novel ability to keep ones body upright while standing or walking, the human balance, deteriorates in old age or can be compromised after accidents or brain surgeries. With the aged society, age related balance problems are on the rise. Persons with balance problems are more likely to fall during their everyday life routines. Especially in elderly, falls can lead to bone fractures making the patient bedridden, weakening the body and making it more prone to other diseases. Health care expenses for a fall patient are often very high. There is a great deal of research being done on exoskeletons and power assists. However, these technologies concentrate mainly on the amplifications of human muscle power while balance has to be provided by the human themself. Our research has been focused on supporting human balance in harmony with the human's own posture control mechanisms such as postural reflexes. This paper proposes an artificial balancer that supports human balance through acceleration of a flywheel attached to the body. Appropriate correcting torques are generated through our device based on the measurements of body deflections. We have carried out experiments with test persons standing on a platform subject to lateral perturbations and ambulatory experiments while walking on a balance beam. These experiments have demonstrated the effectiveness of our device in supporting balance and the possibility of enhancing balance-keeping capability in human beings through the application of external torque. PMID:22169384

  19. Interoception and autonomic nervous system reflexes thermoregulation.

    PubMed

    Fealey, Robert D

    2013-01-01

    Important conceptual changes concerning human thermoregulation have occurred in the last decade. While the hypothalamus maintains its central role in sensing core temperature and providing connectivity to orchestrate heat loss and cold defense autonomic neuronal mechanisms, it is now regarded as one of multiple, independent thermoeffector pathways that control core body temperature. Recent research in primate central and peripheral thermosensitivity has emphasized the importance of temperature-activated transient receptor potential (TRP) channels and afferent neuronal pathways from peripheral thermosensors that are activated by unique combinations of core and shell temperature. The interoceptive aspects of behavioral thermoregulation have been emphasized including the primary importance of shell (skin) temperature, the concept of thermal discomfort and the important contribution of orbitofrontal, insular, somatosensory, and amygdala cortical regions deployed to anticipate and avoid thermal stress. Clinical testing of human thermoregulation requires afferent stimuli to activate the independent thermoeffector loops while monitoring an efferent response. Patterns of sweat gland activation, amount of sweat produced, and areas of anhidrosis demonstrated by the thermoregulatory and axon reflex sweat testing provide diagnostic information about neurological and medical disorders of the autonomic nervous system. PMID:24095117

  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. Effects of repeated Achilles tendon vibration on triceps surae stiffness and reflex excitability.

    PubMed

    Lapole, Thomas; Pérot, Chantal

    2011-02-01

    Clinical studies frequently report an increase in stiffness and a loss of range of motion at joints placed in disuse or immobilization. This is notably the case for subjects maintained in bed for a long period, whilst their joints are not affected. Recently we documented on healthy subjects the benefit in terms of force and activation capacities of the triceps surae offered by vibrations applied to the Achilles tendon. Knowing that stiffness changes may contribute to force changes, the aim of the present study was to investigate the effects of tendon vibration on the triceps surae stiffness of healthy subjects. The vibration program consisted in 14 days of 1h daily Achilles tendon vibration applied at rest. Nineteen healthy students were involved in this study. Before and at the end of the vibration program, musculo-tendinous stiffness in active conditions was determined by use of a quick-release test. Passive stiffness was also analyzed by a flexibility test: passive torque-angle relationships were established from maximal plantar-flexion to maximal dorsiflexion. Passive stiffness indexes at 10°, 15° and 20° dorsiflexion were defined as the slope of the relationships at the corresponding angle. Tendinous reflex, influenced by stiffness values, was also investigated as well as the H reflex to obtain an index of the central reflex excitability. After the program, musculo-tendinous stiffness was significantly decreased (p=.01). At the same time, maximal passive dorsiflexion was increased (p=.005) and passive stiffness indexes at 10°, 15° and 20° dorsiflexion decreased (p<.001; p<.001 and p=.011, respectively). Tendinous reflex also significantly decreased. As the triceps surae parameters are diminished after the vibration program, it could be beneficial to immobilized persons as hypo-activity is known to increase muscular stiffness. PMID:21084200

  2. Naloxone reverses inhibitory effect of electroacupuncture on sympathetic cardiovascular reflex responses.

    PubMed

    Chao, D M; Shen, L L; Tjen-A-Looi, S; Pitsillides, K F; Li, P; Longhurst, J C

    1999-06-01

    Acupuncture and electroacupuncture (EA) have been used in traditional Chinese medicine to treat a wide range of diseases and conditions, including angina pectoris and myocardial infarction. In a feline model of reflex-induced reversible myocardial ischemia, electrical stimulation of the median nerves to mimic EA (Neiguan acupoint) significantly improved ischemic dysfunction, secondary to an inhibitory effect of EA on reflex pressor effects evoked by bradykinin (BK). The central mechanism of EA's inhibitory effect in this model is unknown. Accordingly, in alpha-chloralose-anesthetized cats, BK (10 micrograms/ml) was applied to the gallbladder to elicit a cardiovascular reflex response that significantly (P < 0.05) increased arterial blood pressure and heart rate; normalized systolic wall thickening (%WTh) of the left ventricle, measured by ultrasonic single-crystal sonomicrometer, increased by 31 +/- 11% (P < 0.05). After ligation of a side branch of the left anterior descending coronary artery, the reflex pressor response to BK resulted in a significant decrease of %WTh (-32 +/- 6%) in the ischemic region. When bilateral EA of the Neiguan acupoints was performed, the pressor response to BK was inhibited and regional myocardial function was significantly improved (+19 +/- 20%). The inhibitory effects of EA on blood pressure and %WTh were reversed by intravenous injection of naloxone (0.4 mg/kg; n = 9) or microinjection of naloxone (10 nM in 0.1 microliter/site; n = 14) into the rostral ventrolateral medulla (rVLM). Thus %WTh with intravenous naloxone was reduced to -13 +/- 29% (P<0.05) during stimulation of the gallbladder. Our results indicate that the inhibitory effect of EA on the BK-induced pressor response and the consequent improvement of ischemic dysfunction is dependent on the activation of opioid receptors, specifically receptors located in the rVLM. PMID:10362696

  3. Electroneurographic correlates of the monosynaptic reflex: experimental studies and normative data.

    PubMed Central

    Abbruzzese, M; Ratto, S; Abbruzzese, G; Favale, E

    1985-01-01

    The neurographic concomitants of the monosynaptic reflex, evoked either by electrical stimulation of the tibial nerve at the popliteal fossa or by percussion of the Achilles tendon, have been recorded from the sciatic nerve in the lower and middle thigh. Neurographic recordings were characterised by two travelling waves (P1 and P2), respectively increasing and decreasing in latency in the proximal direction, that showed the same chronological trend of the propagated action potentials concurrently recorded in the dorsal and ventral spinal roots at the lumbar level. At variance with P2, the speed of propagation of the P1 volley was stimulus-related, being faster on mechanical than on electrical stimulation, probably because in the latter case the latency of the fastest afferents is overestimated. The P2 volley is subserved by alpha-efferent fibres in either case as suggested, inter alia, by the strict parallelism between the P2 volley and the monosynaptic reflex under appropriate experimental conditions. Simultaneous recordings of spinal root and sciatic nerve action potentials allowed the direct assessment of afferent and efferent conduction velocities, both in the proximal (that is from the middle thigh to the spinal recording site and vice-versa) and in the distal (that is from the lower to the middle thigh recording site and vice versa) segments of the reflex arc. As expected, the speed of propagation of impulses was significantly higher in the proximal than in the distal segments, as well as in the afferent than in efferent limb of the monosynaptic pathway. The P1-P2 time interval was longer on mechanical than on electrical stimulation, probably due to the increased spinal delay of the T versus the H reflex. The present study provides a reliable method for the direct assessment of alpha-efferent as well as of Ia afferent group fibres conduction velocity, provided that in the latter case mechanical stimuli be used. PMID:3998752

  4. Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex

    PubMed Central

    Steinhauer, Stuart R.; Condray, Ruth; Pless, Misha L.

    2015-01-01

    Cognitive operations can be detected by reduction of the pupillary light response. Neurophysiological pathways mediating this reduction have not been distinguished. We utilized selective blockade of pupillary sphincter or dilator muscles to isolate parasympathetic or sympathetic activity during cognition, without modifying central processes. Pupil diameter was measured during the light reaction in 29 normal adults under three processing levels: No Task, during an easy task (Add 1), or a difficult task (Subtract 7). At three separate sessions, the pupil was treated with placebo, tropicamide (blocking the muscarinic sphincter receptor), or dapiprazole (blocking the adrenergic dilator receptor). With placebo, pupil diameter increased with increasing task difficulty. The light reaction was reduced only in the Subtract 7 condition. Dapiprazole (which decreased overall diameter) showed similar task-related changes in diameter and light reflex as for placebo. Following tropicamide (which increased overall diameter), there was a further increase in diameter only in the difficult task. Findings suggest two separate inhibitory components at the parasympathetic oculomotor center. Changes in baseline diameter are likely related to reticular activation. Inhibition of the light reaction in the difficult task is likely associated with cortical afferents. Sustained sympathetic activity also was present during the difficult task. PMID:26090217

  5. 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.

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

    PubMed Central

    Sloot, Lizeth H.; van den Noort, Josien C.; van der Krogt, Marjolein M.; Bruijn, Sjoerd M.; Harlaar, Jaap

    2015-01-01

    Disinhibition of reflexes is a problem amongst spastic patients, for it limits a smooth and efficient execution of motor functions during gait. Treadmill belt accelerations may potentially be used to measure reflexes during walking, i.e. by dorsal flexing the ankle and stretching the calf muscles, while decelerations show the modulation of reflexes during a reduction of sensory feedback. The aim of the current study was to examine if belt accelerations and decelerations of different intensities applied during the stance phase of treadmill walking can evoke reflexes in the gastrocnemius, soleus and tibialis anterior in healthy subjects. Muscle electromyography and joint kinematics were measured in 10 subjects. To determine whether stretch reflexes occurred, we assessed modelled musculo-tendon length and stretch velocity, the amount of muscle activity, as well as the incidence of bursts or depressions in muscle activity with their time delays, and co-contraction between agonist and antagonist muscle. Although the effect on the ankle angle was small with 2.8±1.0°, the perturbations caused clear changes in muscle length and stretch velocity relative to unperturbed walking. Stretched muscles showed an increasing incidence of bursts in muscle activity, which occurred after a reasonable electrophysiological time delay (163–191 ms). Their amplitude was related to the muscle stretch velocity and not related to co-contraction of the antagonist muscle. These effects increased with perturbation intensity. Shortened muscles showed opposite effects, with a depression in muscle activity of the calf muscles. The perturbations only slightly affected the spatio-temporal parameters, indicating that normal walking was retained. Thus, our findings showed that treadmill perturbations can evoke reflexes in the calf muscles and tibialis anterior. This comprehensive study could form the basis for clinical implementation of treadmill perturbations to functionally measure reflexes during treadmill-based clinical gait analysis. PMID:26669665

  7. 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

  8. Gravity and Development of Cardiopulmonary Reflex

    NASA Astrophysics Data System (ADS)

    Nagaoka, Shunji; Eno, Yuko; Ohira, Yoshinobu

    Cardio-pulmonary reflex, which our cardiac activity is synchronized to the respiration by autonomic nervous system regulation, is called as "respiratory sinus arrhythmia" and commonly found in adult. The physiological function of the espiratory sinus arrhythmia is considered to maximize the gas exchange during respiration cycle. This respiration induced heart rate variability (RHRV) is only found in mammals and avian showing a remarkable postnatal development, whereas no RHRV in aquatic species such as fish or amphibian. To elucidate our hypothesis that gravity exposure may plays a key role in the postnatal development of RHRV as well as its evolutional origin in these ground animals, we have studied effects of hypergravity (2G) on the postnatal development of RHRV using rat. Pregnant Wister rats were kept in centrifugal cages system for 38 days from 6th days of pregnant mother to have neonates until 23 days old. Electrocardiograph was recorded from the neonates in 2 to 23 days old in 2G group with simultaneous control (1G) group. The RHRV analysis was performed by calculating a component of Fourier power spectral coincide with the respiration frequency. In both groups, averaged resting heart rate gradually increase from 2 to 23 days old. When comparing the heart rate between the two groups, the 2G group indicated significantly lower (240± 8 bpm) than 1G control (326±21 bpm, p¡0.001) in 2 days old, where as no significance in 23 days old. The RHRV of 2 days old neonates in both groups indicated very small magnitude but significantly lower in 2G group than 1G control (p¡0.01). The RHRV gradually increase during the first 2 weeks and then rapid increased to reached 45 fold of magnitude in 1G control, whereas 69 fold in 2G group. The results strongly suggested that the postnatal innervation from respiration to cardiovascular centers was gravity dependent.

  9. 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.

  10. 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.

  11. 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.

  12. Long lasting activity of nociceptive muscular afferents facilitates bilateral flexion reflex pattern in the feline spinal cord.

    PubMed

    Schomburg, E D; Steffens, H; Pilyavskii, A I; Maisky, V A; Brück, W; Dibaj, P; Sears, T A

    2015-06-01

    Chronic muscular limb pain requires the adoption of motor patterns distinct from the classic ipsilateral flexion, crossed extension and corresponding reciprocal inhibitions to acute exteroceptive stimulation. Using selective chemical activation of group III/IV afferents in gastrocnemius-soleus (GS) muscles we investigated bilaterally their reflex responses conditioned by (a) acute 'myositis' induced by intramuscular carrageenan; and (b) sub-acute 'myositis' induced by infusion of complete Freund's adjuvant (CFA). Reflex transmission was detected by monosynaptic testing and c-fos staining used to identify increased neuronal activity. In all control experiments with chemical stimulation of group III/IV afferents, ipsilateral responses conformed to the flexor reflex pattern. However, the expected contralateral facilitation of GS motoneurones occurred in fewer than 50% trials while only 9% of trials induced contralateral inhibition of flexor posterior-biceps-semitendinosus (PBSt) motoneurones. During carrageenan acute myositis contralateral PBSt was transiently facilitated by selective activation of group III/IV afferents. During CFA-induced myositis, contralateral only inhibition of GS motoneurones occurred instead of any facilitation, while bidirectionally a crossed facilitation of PBST dominated. These reflex changes were mirrored in an enhanced number of neurones with enhanced c-fos expression. Muscle pain, particularly if chronically persistent, requires another behavioural response pattern than acute exteroceptive pain. PMID:25615850

  13. The pulse duration of electrical stimulation influences H-reflexes but not corticospinal excitability for tibialis anterior.

    PubMed

    Hindle, Alyssa R; Lou, Jenny W H; Collins, David F

    2014-10-01

    The afferent volley generated by neuromuscular electrical stimulation (NMES) influences corticospinal (CS) excitability and frequent NMES sessions can strengthen CS pathways, resulting in long-term improvements in function. This afferent volley can be altered by manipulating NMES parameters. Presently, we manipulated one such parameter, pulse duration, during NMES over the common peroneal nerve and assessed the influence on H-reflexes and CS excitability. We hypothesized that compared with shorter pulse durations, longer pulses would (i) shift the H-reflex recruitment curve to the left, relative to the M-wave curve; and (ii) increase CS excitability more. Using 3 pulse durations (50, 200, 1000 ?s), M-wave and H-reflex recruitment curves were collected and, in separate experiments, CS excitability was assessed by comparing motor evoked potentials elicited before and after 30 min of NMES. Despite finding a leftward shift in the H-reflex recruitment curve when using the 1000 ?s pulse duration, consistent with a larger afferent volley for a given efferent volley, the increases in CS excitability were not influenced by pulse duration. Hence, although manipulating pulse duration can alter the relative recruitment of afferents and efferents in the common peroneal nerve, under the present experimental conditions it is ineffective for maximizing CS excitability for rehabilitation. PMID:25223503

  14. Colon mustard oil instillation induced cross-organ reflex sensitization on the pelvic-urethra reflex activity in rats.

    PubMed

    Peng, Hsien-Yu; Chen, Gin-Den; Tung, Kwong-Chung; Lai, Cheng-Yuan; Hsien, Ming-Chun; Chiu, Chun-Hsien; Lu, Hsiao-Ting; Liao, Jiuan-Miaw; Lee, Shin-Da; Lin, Tzer-Bin

    2009-03-01

    We investigated the participation of cyclin-dependent kinase-5 (Cdk5)-mediated N-methyl-D-aspartate receptor (NMDAR) NR2B subunit phosphorylation in cross-organ reflex sensitization caused by colon irritation. The external urethral sphincter electromyogram (EUSE) reflex activity evoked by the pelvic afferent nerve test stimulation (TS, 1 stimulation/30s) and protein expression in the spinal cord and dorsal root ganglion tissue (T13-L2 and L6-S2 ipsilateral to the stimulation) in response to colon mustard oil (MO) instillation were tested in anesthetized rats. When compared with a baseline reflex activity with a single action potential evoked by the TS before the administration of test agents, MO instillation into the descending colon sensitized the evoked activity characterized by elongated firing in the reflex activity in association with increased protein levels of Cdk5, PSD95, and phosphorylated NR2B (pNR2B) but not of total NR2B (tNR2B) in the spinal cord tissue. Both cross-organ reflex sensitization and increments in protein expression were reversed by intra-colonic pretreatments with ruthenium red (a non-selective transient receptor potential vanilloid, TRPV, antagonist), capsaizepine (a TRPV1-selective antagonist), lidocaine (a nerve conduction blocker) as well as by the intra-thecal pretreatment with APV (a NRMDR antagonist) Co-101244 (a NR2B-selective antagonist) and roscovitine (a Cdk5 antagonist). Moreover, compared with the control group, both the increase in pNR2B and the cross-organ reflex sensitization were attenuated in the si-RNA of NR2B rats. All these results suggested that Cdk-dependent NMDAR NR2B subunit phosphorylation mediates the development of cross-organ pelvic-urethra reflex sensitization caused by acute colon irritation which could possibly underlie the high concurrence of pelvic pain syndrome with irritable bowel syndrome. PMID:19167822

  15. 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.

  16. Primitive reflexes and postural reactions in the neurodevelopmental examination.

    PubMed

    Zafeiriou, Dimitrios I

    2004-07-01

    The primitive reflexes and the postural reactions comprise one of the earliest, simplest, and most frequently used tools among child neurologists to assess the central nervous system integrity of infants and young children. Infants with cerebral palsy have been known to manifest persistence or delay in the disappearance of primitive reflexes and pathologic or absent postural reactions. The clinical significance of asymmetric tonic neck reflex, Moro, palmar grasp, plantar grasp, Galant, Babinski, Rossolimo, crossed extensor, suprapubic extensor, and heel reflex, alone or in combination, as well as their contribution to the early diagnosis and differential diagnosis of cerebral palsy, have been demonstrated in a number of studies. Moreover, infants with 5 or more abnormal postural reactions have developed either cerebral palsy or developmental retardation as reported in a number of studies. Although a comprehensive neurologic examination in the context of a motor assessment instrument is preferable to an informal list of items, the combined examination of primitive reflexes and postural reactions should be considered by the child neurologist, as a simple but predictive screening test for the early identification of infants at risk for cerebral palsy. It is quick and easy to perform, both in nonhospital environments and in underdeveloped countries, where time and specific recourses are limited. The combined examination is also useful in developed countries because many developmental disorders such as cerebral palsy appear in nonrisk groups whereas others are not detected by metabolic screening programs. PMID:15246484

  17. Central and peripheral mechanisms underlying gastric distention inhibitory reflex responses in hypercapnic-acidotic rats.

    PubMed

    Tjen-A-Looi, Stephanie C; Hsiao, An-Fu; Longhurst, John C

    2011-03-01

    We have observed that in chloralose-anesthetized animals, gastric distension (GD) typically increases blood pressure (BP) under normoxic normocapnic conditions. However, we recently noted repeatable decreases in BP and heart rate (HR) in hypercapnic-acidotic rats in response to GD. The neural pathways, central processing, and autonomic effector mechanisms involved in this cardiovascular reflex response are unknown. We hypothesized that GD-induced decrease in BP and HR reflex responses are mediated during both withdrawal of sympathetic tone and increased parasympathetic activity, involving the rostral (rVLM) and caudal ventrolateral medulla (cVLM) and the nucleus ambiguus (NA). Rats anesthetized with ketamine and xylazine or ?-chloralose were ventilated and monitored for HR and BP changes. The extent of cardiovascular inhibition was related to the extent of hypercapnia and acidosis. Repeated GD with both anesthetics induced consistent falls in BP and HR. The hemodynamic inhibitory response was reduced after blockade of the celiac ganglia or the intraabdominal vagal nerves with lidocaine, suggesting that the decreased BP and HR responses were mediated by both sympathetic and parasympathetic afferents. Blockade of the NA decreased the bradycardia response. Microinjection of kainic acid into the cVLM reduced the inhibitory BP response, whereas depolarization blockade of the rVLM decreased both BP and HR inhibitory responses. Blockade of GABA(A) receptors in the rVLM also reduced the BP and HR reflex responses. Atropine methyl bromide completely blocked the reflex bradycardia, and atenolol blocked the negative chronotropic response. Finally, ?(1)-adrenergic blockade with prazosin reversed the depressor. Thus, in the setting of hypercapnic-acidosis, a sympathoinhibitory cardiovascular response is mediated, in part, by splanchnic nerves and is processed through the rVLM and cVLM. Additionally, a vagal excitatory reflex, which involves the NA, facilitates the GD-induced decreases in BP and HR responses. Efferent chronotropic responses involve both increased parasympathetic and reduced sympathetic activity, whereas the decrease in BP is mediated by reduced ?-adrenergic tone. PMID:21217073

  18. ACQUISITION OF A SIMPLE MOTOR SKILL: TASK-DEPENDENT ADAPTATION PLUS LONG-TERM CHANGE IN THE HUMAN SOLEUS H-REFLEX

    PubMed Central

    Thompson, A.K.; Chen, X.Y.; Wolpaw, J.R.

    2009-01-01

    Activity-dependent plasticity occurs throughout the CNS. However, investigations of skill acquisition usually focus on cortex. To expand the focus, we analyzed in humans the development of operantly conditioned H-reflex change, a simple motor skill that develops gradually and involves plasticity in both the brain and the spinal cord. Each person completed 6 baseline and 24 conditioning sessions over 10 weeks. In each conditioning session, the soleus H-reflex was measured while the subject was or was not asked to increase (HRup subjects) or decrease (HRdown subjects) it. When the subject was asked to change H-reflex size, immediate visual feedback indicated whether a size criterion had been satisfied. Over the 24 conditioning sessions, H-reflex size gradually increased in 6 of 8 HRup subjects and decreased in 8 of 9 HRdown subjects, resulting in final sizes of 140(±12)% and 69(±6)% of baseline size, respectively. The final H-reflex change was the sum of within-session (i.e., task-dependent) adaptation and across-session (i.e., long-term) change. Task-dependent adaptation appeared within 4–6 sessions and persisted thereafter, averaging +13% in HRup subjects and ?15% in HRdown subjects. In contrast, long-term change began after 10 sessions and increased gradually thereafter, reaching +27% in HRup subjects and ?16% in HRdown subjects. Thus, the acquisition of H-reflex conditioning consists of two phenomena – task-dependent adaptation and long-term change – that together constitute the new motor skill. In combination with previous data, this new finding further elucidates the interaction of plasticity in brain and spinal cord that underlies the acquisition and maintenance of motor skills. PMID:19420246

  19. Lung C-fibre receptor activation and defensive reflexes in anaesthetized cats.

    PubMed Central

    Tatar, M; Webber, S E; Widdicombe, J G

    1988-01-01

    1. With pentobarbitone-anaesthetized cats we have elicited cough reflexes from the tracheobronchial tree and the larynx, and the aspiration and sneeze reflexes from the nasopharynx and the nose respectively. The reflexes were induced by mechanical stimulation of the mucosa, before and during activation of pulmonary C-fibre receptors by intravenous injections of capsaicin or phenylbiguanide. 2. During the 20-30 s apnoea due to C-fibre stimulation, the cough reflex from both sites and the sneeze reflex were completely abolished, whereas the aspiration reflex response was approximately halved. Reflex contractions of genioglossus muscle still occurred at this time, but were far weaker than in the control state. 3. During the rapid shallow breathing that immediately followed apnoea due to C-fibre receptor stimulation, the defensive reflexes recovered: the aspiration and sneeze reflexes fully and the cough reflexes to about half of the control response. 4. Acute hypotension due to haemorrhage, of a size considerably greater than that due to stimulation of the pulmonary C-fibre receptors, caused no significant inhibition of the cough reflex from the tracheobronchial tree. 5. We conclude that the pulmonary C-fibre reflex powerfully inhibits airway defensive reflexes, and that its activation is unlikely to contribute positively to coughing induced by aerosols of capsaicin and similar agents. PMID:3236245

  20. Current-voltage Characteristics of the high Pressure Reflex Discharge in Helium

    NASA Astrophysics Data System (ADS)

    Liziakin, Gennadii; Usmanov, Ravil

    In this paper the high pressure reflex discharge is investigated. Conditions for the discharge transition from a low-current to a high-current mode are considered. The study of the discharge is carried out in the atmosphere of helium at pressures from 1 to 35 mTorr, with a magnetic field up to 2.1 kG and voltage up to 1.2 kV. The radial profile of the potential distribution in the central plane of the discharge (perpendicular to the axis) was obtained by the isolated probe method.

  1. Direct and consensual murine pupillary reflex metrics: Establishing normative values

    PubMed Central

    Hussain, Rehana Z.; Hopkins, Steven C.; Frohman, Elliot M.; Eagar, Todd N.; Cravens, Petra C.; Greenberg, Benjamin M.; Vernino, Steven; Stüve, Olaf

    2014-01-01

    Pupillometry is a non-invasive technique, based on well-established neurophysiologic principles, that can be utilized to objectively characterize pathophysiologic demyelinating and neurodegenerative changes involving the pupillary reflex pathway. In animal models of human disorders, pupillometry derived reflex metrics could potentially be used to longitudinally monitor disease activity and responses to pharmacotherapies. These investigations would have important implications for translational initiatives focused on the identification and application of novel neuroprotective and restorative treatments for human diseases such as multiple sclerosis. Here, we have established normal reference values for various pupillary reflex metrics across different mouse strains. Ultimately, we anticipate that this new data will help to catalyze unique lines of inquiry using pupillometry methods. PMID:19683968

  2. Trigeminal reflexes and ingestive behavior in the rat.

    PubMed

    Zeigler, H P; Semba, K; Jacquin, M F

    1984-12-01

    Photographic, electrophysiological, and neurobehavioral analyses were used to examine the contribution of trigeminally mediated jaw-opening reflexes to the control of ingestive behavior in the rat. During eating and drinking, jaw opening was always preceded by a period of perioral contact with the food or water source. Stimulation (electrical, mechanical) of perioral areas in anesthetized animals elicited jaw-opening reflexes (recorded from the mylohyoid nerve trunk) at short latencies and low stimulus intensities. Trigeminal orosensory deafferentation (sparing jaw muscle afferents and efferents, taste, vision, and olfaction) abolished or significantly reduced mouth opening during eating or drinking. It is concluded that motivational processes operate through trigeminal reflexes to generate eating in the rat. PMID:6508909

  3. A Heart Stopping Case of the Bezold-Jarisch Reflex

    PubMed Central

    2015-01-01

    The Bezold-Jarisch reflex is a parasympathetic reflex induced by intense mechanical stimulation of the ventricular myocytes. Exceptionally, cases have been described in patients receiving dobutamine infusion during a stress echocardiography. All were healthy middle-aged women and recovered without sequelae. A healthy 60-year-old woman suffered two 5.9-second episodes of asystole during her 20?mcg/kg/min infusion of dobutamine. Recovery was quick and without sequelae. Echocardiography and coronary angiography were both normal. In conclusion, this is the fourth documented case of a severe Bezold-Jarisch reflex causing asystole during dobutamine infusion. Diagnosis can only be made after excluding all other possible diagnoses, most importantly ischemia. This serves as a reminder of the importance of close monitoring during dobutamine infusion. PMID:26697234

  4. Single Canonical Model of Reflexive Memory and Spatial Attention.

    PubMed

    Patel, Saumil S; Red, Stuart; Lin, Eric; Sereno, Anne B

    2015-01-01

    Many neurons in the dorsal and ventral visual stream have the property that after a brief visual stimulus presentation in their receptive field, the spiking activity in these neurons persists above their baseline levels for several seconds. This maintained activity is not always correlated with the monkey's task and its origin is unknown. We have previously proposed a simple neural network model, based on shape selective neurons in monkey lateral intraparietal cortex, which predicts the valence and time course of reflexive (bottom-up) spatial attention. In the same simple model, we demonstrate here that passive maintained activity or short-term memory of specific visual events can result without need for an external or top-down modulatory signal. Mutual inhibition and neuronal adaptation play distinct roles in reflexive attention and memory. This modest 4-cell model provides the first simple and unified physiologically plausible mechanism of reflexive spatial attention and passive short-term memory processes. PMID:26493949

  5. Single Canonical Model of Reflexive Memory and Spatial Attention

    PubMed Central

    Patel, Saumil S.; Red, Stuart; Lin, Eric; Sereno, Anne B.

    2015-01-01

    Many neurons in the dorsal and ventral visual stream have the property that after a brief visual stimulus presentation in their receptive field, the spiking activity in these neurons persists above their baseline levels for several seconds. This maintained activity is not always correlated with the monkey’s task and its origin is unknown. We have previously proposed a simple neural network model, based on shape selective neurons in monkey lateral intraparietal cortex, which predicts the valence and time course of reflexive (bottom-up) spatial attention. In the same simple model, we demonstrate here that passive maintained activity or short-term memory of specific visual events can result without need for an external or top-down modulatory signal. Mutual inhibition and neuronal adaptation play distinct roles in reflexive attention and memory. This modest 4-cell model provides the first simple and unified physiologically plausible mechanism of reflexive spatial attention and passive short-term memory processes. PMID:26493949

  6. 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.

  7. Acupuncture - An effective tool in the management of gag reflex

    PubMed Central

    Anand, M. Vijay; Rai, Rathika; Bettie, Nirmal F.; Ramachandiran, Hari; Solomon; Praveena, Subramaniyam

    2015-01-01

    Gagging is of great concern to the dentist as it is a serious impediment during the execution of various dental procedures. The etiology of gagging is multifactorial, and several suggestions have been offered to arrest this reflex, some of which are nonsustainable and does not show the immediate result. Acupuncture has been successfully employed as an adjunct to local anesthesia in dental extractions, pain management and also in the symptomatic management of temporomandibular joint disorders. The author highlights the application of acupuncture in the management of patients with gag reflex during dental procedures and its benefits are reported. PMID:26538942

  8. Operating characteristics of a magnetically insulated reflex ion diode

    SciTech Connect

    Strobel, G.L.

    1982-08-01

    Steady-state space charge limited-flow calculations have been carried out for an applied B/sub theta/ magnetically insulated reflexing ion diode. Reflex ion energy spectra characteristic of a thin foil cathode and of a transparent mesh have been used. A one-dimensional calculation shows higher ion current densities with a mesh cathode, and that the emission electron current density increases with the applied B/sub theta/ magnetic field. The ion current density is calculated to increase slightly with radius.

  9. [Changes in the deglutition reflex during the perioperative period].

    PubMed

    de Larminat, V; Dureuil, B

    1994-01-01

    The swallowing reflex is one of the major mechanisms protecting the lungs against aspiration of foreign material. Its complex time course requires a perfect coordination with ventilation, as the aerodigestive crossroads are common for both functions. Physiological factors as ageing, as well as mechanical and pharmacological agents, may contribute to swallowing reflex alterations. Moreover, endotracheal intubation and most anaesthetic agents may impair the swallowing function and favour the occurrence of aspiration. This review discusses the normal swallowing process and its alterations by agents currently used in anaesthesia. Furthermore, the effect of intubation as well as changes related to co-existing diseases are considered. PMID:8092580

  10. Cardiac sympathetic afferent reflex in dogs with congestive heart failure.

    PubMed

    Wang, W; Zucker, I H

    1996-09-01

    It is well accepted that sympathetic tone is elevated in chronic heart failure (HF) and that the cardiac sympathetic afferent reflex is a sympathoexcitatory reflex. There have been no studies designed to examine the role of this reflex in control of sympathetic outflow in the HF state. In this study we tested the hypothesis that cardiac sympathetic afferent reflexes are enhanced in HF and are, therefore, capable of contributing to the increase in sympathetic outflow in this disease state. Ventricular pacing was carried out in 14 dogs until signs of HF were evident. Fourteen sham dogs served as controls. At the time of the acute experiment the dogs were anesthetized with alpha-chloralose. The hemodynamic [arterial pressure and heart rate (HR)] and renal sympathetic nerve activity (RSNA) responses to left ventricular epicardial application of two doses of bradykinin (BK) and capsaicin (Cap) were determined in the sinoaortic-denervated and vagotomized state. The MAP, RSNA, and HR responses to BK were greater in the HF group compared with the sham group. The RSNA response to BK (50 micrograms) in the HF group was significantly increased (34.0 +/- 5.9 vs. 11.5 +/- 4.2%, P < 0.05). The MAP, RSNA, and HR responses to Cap in the HF group were similar to the responses to BK. The RSNA response to Cap in the HF group was significantly increased (29.8 +/- 11.3 vs. 13.8 +/- 2.3% for 10 micrograms, P < 0.05 and 46.5 +/- 10.7 vs. 18.7 +/- 3.1% for 100 micrograms, P < 0.05). The cyclooxygenase blocker indomethacin (5 mg/kg i.v.) attenuated the reflex responses to BK in the HF group. These data suggest that the enhanced cardiac sympathetic afferent reflex to epicardial BK in HF appears to be mediated by altered levels of prostaglandin synthesis. Blockade of cardiac sympathetic afferents with topical lidocaine reduced baseline of RSNA significantly more in the HF state than in the normal state (-24.2 +/- 3.6 vs. -4.3 +/- 4.5%, P < 0.05). We conclude from these data that the cardiac sympathetic afferent reflex is sensitized in the HF state and speculate that this enhanced cardiac sympathetic afferent reflex may contribute to the sustained higher sympathetic tone in chronic HF. PMID:8853400

  11. The reluctance to self-disclose: reflexive or reasoned?

    PubMed

    Sugarman, Alan

    2012-07-01

    Despite a growing body of clinical literature advocating the thoughtful and judicious use of self-disclosure in psychoanalysis, there remains a reflexive reluctance to intervene in this way by many analysts of various theoretical persuasions. Why is this the case? Four motives for this reflexive reluctance to self-disclose are discussed: (1) theoretical reasons; (2) psychoanalytic authoritarianism; (3) fears of influencing the patient through suggestion; and (4) the analyst's personality characteristics. Examining the reasons for this state of affairs should help to reduce the rigidity or orthodoxy with which clinical psychoanalysis is practiced. PMID:23038902

  12. Foveation dynamics in congenital nystagmus. III: Vestibulo-ocular reflex.

    PubMed

    Dell'Osso, L F; van der Steen, J; Steinman, R M; Collewijn, H

    1992-01-01

    It has been shown that, during fixation of a stationary target with a fixed head, an individual with congenital nystagmus (CN) can repeatedly (beat-to-beat) foveate (within 13 minarc) and maintain low retinal slip velocities (less than 4 degrees/sec). With the head in motion, vestibuloocular reflex (VOR) data showed eye velocities during these foveation periods that approximation head velocity. Despite some claims that the VOR of CN subjects was deficient or absent, individuals with CN hardly ever complain of oscillopsia or exhibit any of the symptoms that would accompany such deficits in the VOR, whether during simple walking and running or while skiing down a mogul field. We developed and describe several different and unrelated methods to accurately assess the function of the VOR in an individual with typical idiopathic CN. We investigated the dynamics of CN foveation periods during head rotation to test the hypothesis that eye velocities would match head velocities during these periods. At about 1 Hz, horizontal VOR instantaneous (beat-to-beat) gains were 0.96 in the light and 0.94 in the dark while imaging a stationary target. Vertical VOR gains were 1.00 and 0.99 for these two conditions at the same frequency; the CN was horizontal. Also, during the VOR there is a CN neutral-zone shift comparable to that found during smooth pursuit. Our methods demonstrated that gaze velocity was held constant during foveation periods and we conclude that the VOR in this subject is functioning normally in the presence of the CN oscillation. Based on our findings in this and previous studies, we hypothesize that CN may be due to a peripheral instability. PMID:1568422

  13. Features of vestibuloocular reflex modulations induced by altered gravitational forces in tadpoles ( Xenopus laevis)

    NASA Astrophysics Data System (ADS)

    Sebastian, C.; Horn, E.

    2001-01-01

    In Xenopus laevis tadpoles, we studied the static vestibuloocular reflex (rVOR) in relation to modifications of the gravitational environment to find basic mechanisms of how altered gravitational forces (AGF) affect this reflex. Animals were exposed to microgravity during space flight or hypergravity (3g) for 4 to 12 days. Basic observations were that (1) the development of the rVOR is significantly affected by altered gravitational conditions, (2) the duration of 1g-readaptation depends on the strength of the test stimulus, (3) ?g induces malformations of the body which are related to the rVOR depression. Future studies are based on the hypotheses (1) that the vestibular nuclei play a key roll in the adaptation to AGF conditions, (2) that the stimulus transducing systems in the sense organ are affected by AGF conditions, and (3) that fertilized eggs will be converted to normal adults guided by physiological and morphological set points representing the genetic programs. Developmental retardation or acceleration, or otherwise occurring deviations from standard development during embryonic and postembryonic life will activate genes that direct the developmental processes towards normality.

  14. [Transformation of conditioned responses of the tonic type].

    PubMed

    Borukaev, R K

    1978-01-01

    A reversal of signal meaning of stimuli signalling experimental situation was performed on dogs with conditioned defensive motor reflexes to clicks: clicks and electro-cutaneous stimulation were stopped, and the animals were started to be given food in the same experimental situation. Reversal of conditioned defensive tonic stimuli to alimentary ones led to a complex of behavioral and electrographic reactions. Isolated click tests showed that signals of experimental situation considerably affect a fully-elaborated defensive motor reflex. At the same time the preparatory role of certain situational elements may be specialized with regard to the components of the conditioned reflex, in particular to the local flexor reaction. PMID:676493

  15. Role of positive urethrovesical feedback in vesical evacuation. The concept of a second micturition reflex: the urethrovesical reflex.

    PubMed

    Shafik, Ahmed; Shafik, Ali A; El-Sibai, Olfat; Ahmed, Ismail

    2003-08-01

    Upon feeling the urge to urinate, the urinary bladder contracts, the urethral sphincters relax and urine flows through the urethra. These actions are mediated by the micturition reflex. We investigated the hypothesis that vesical contraction is maintained by positive feedback through continuous flow of urine through the urethra, and that the cessation of urine flow aborts detrusor contraction. Normal saline was infused into the urinary bladders of 17 healthy volunteers (age 35.2 years+/-4.2(SD); ten women and seven men) at a rate of 100 ml/min. On urge, which occurred at a mean volume of 408.6 ml+/-28.7 of saline, the subject micturated while the vesical and urethral pressures during voiding were being recorded; residual urine was measured. The test was repeated after anesthetizing the urethra with xylocaine gel or, on another occasion, after applying a bland gel. On micturition, the urine was evacuated as a continuous stream without straining; no residual fluid was collected. After urethral anesthetization, the fluid came out of the urethra in multiple intermittent spurts and only with excessive straining. There was a large amount of residual fluid (184.6 ml+/-28.4). The results of bland gel application showed no significant difference ( P>0.05) from those without gel. Detrusor contraction during micturition is suggested to be maintained by positive urethrovesical feedback elicited by the continued passage of urine through the urethra. This feedback seems to be effected through the urethrovesical reflex, which produces vesical contraction on stimulation of the urethral stretch receptors. Abortion of this reflex by urethral anesthetization resulted in failure of detrusor contraction and excessive straining was needed to achieve bladder evacuation in multiple spurts. The urethrovesical reflex is thus assumed to constitute a second micturition reflex responsible for the continuation of detrusor contraction and urination. The role of this reflex in the pathogenesis of micturition disorders needs to be studied. PMID:12898170

  16. Does neuroticism in adolescents moderate contextual and explicit threat cue modulation of the startle reflex?

    PubMed Central

    Craske, Michelle G.; Waters, Allison M.; Nazarian, Maria; Mineka, Susan; Zinbarg, Richard E.; Griffith, James W.; Naliboff, Bruce; Ornitz, Edward M.

    2009-01-01

    Background This study evaluated the relationship between neuroticism (N), a probable risk factor for emotional disorders, and modulation of startle reflexes (SRs). Methods 132 adolescents with varying levels of N, but without anxiety or depressive disorders, were evaluated in contextual cue and explicit threat cue paradigms. Results Within the explicit threat cue paradigm, N potentiated SRs more in conditions that were intermediately associated with threat of an aversive biceps contraction than conditions that were the furthest from and conditions that were the closest to the same threat. Also, N potentiated SRs across the entire experiment, regardless of experimental conditions, in males and not in females. Discussion These results suggest that adolescents with high levels of N show greater sensitivity to contexts intermediately associated with threat. Results are discussed in comparison to other studies of groups at risk for anxiety and depressive disorders. PMID:18789433

  17. 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…

  18. On Being a Nice Country Girl and an Academic Feminist: Using Reflexivity in Rural Social Research

    ERIC Educational Resources Information Center

    Pini, Barbara

    2004-01-01

    This paper uses a study of women's participation in the Australian sugar industry to illustrate and critique the process and usefulness of reflexivity in rural research. I begin by situating the use of reflexivity within the feminist literature. Following this, I describe the way in which I used reflexivity to examine different identities I…

  19. 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…

  20. Reflex Modification by Acoustic Signals in Newborn Infants and in Adults.

    ERIC Educational Resources Information Center

    Hoffman, Howard S.; And Others

    1985-01-01

    Five experiments using identical reflex modification procedures on neonates and adults suggest developmental differences in processing auditory stimuli. Neonates failed to exhibit reflex inhibition by either prior acoustic or tactile stimuli. Adults exhibited robust reflex inhibition to these same stimuli. Developmental processes implied by these…

  1. 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

  2. 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…

  3. Uraemic myoclonus: an example of reticular reflex myoclonus?

    PubMed Central

    Chadwick, D; French, A T

    1979-01-01

    Two patients are described who developed action, reflex myoclonus during acute renal failure. In both cases the myoclonus was abolished after the intravenous administration of clonazepam. We suggest that the characteristic action myoclonus, which occurs in both acute renal failure and postanoxic encephalopathy, is caused by a disturbance of function in the lower brainstem reticular formation. PMID:762584

  4. Reconceptualising Learning as a Form of Relational Reflexivity

    ERIC Educational Resources Information Center

    Dyke, Martin

    2015-01-01

    The paper makes a connection between transmission modes and constructivism in sociology and education, respectively. There are parallels between Archer's criticism of upward and downward conflation in social theory, and approaches to learning in education. In her 2012 book, Archer seeks to reconceptualise socialisation as relational reflexivity

  5. Reconceptualizing reflexivity and dissonance in professional and personal domains.

    PubMed

    Brooks, Ann

    2008-09-01

    Debates around 'reflexivity' and the construction of the gendered self within late modernity have occupied the attention of both 'reflexive modernization' theorists (Beck, Giddens and Lash 1994; Beck and Beck-Gernsheim 1996; Giddens 1991, 1992) as well as gender and feminist theorists. While theorists such as Beck and Giddens have been preoccupied with establishing the connection between reflexivity and the construction of the 'non-gendered' self, gender and feminist theorists have sought to amplify the debate by exploring the intersecting nexus of contemporary theorizing, more fully within this context. This paper explores the theoretical underpinnings of these debates and their application to specific professional and personal domains. I consider three case studies to assess these issues as outlined in my own work, Brooks 2006, and in the work of Wajcman and Martin 2002, and McDowell 1997, which draw on empirical research and explore changes to gender identity within professional and personal domains. I conclude that there is little evidence in the research presented here of any systematic reconfiguring of gender identities leading to a detraditionalization of gender as suggested by the 'reflexive modernization' theorists. PMID:18782154

  6. Reconceptualising Learning as a Form of Relational Reflexivity

    ERIC Educational Resources Information Center

    Dyke, Martin

    2015-01-01

    The paper makes a connection between transmission modes and constructivism in sociology and education, respectively. There are parallels between Archer's criticism of upward and downward conflation in social theory, and approaches to learning in education. In her 2012 book, Archer seeks to reconceptualise socialisation as relational reflexivity.…

  7. 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…

  8. Sympathetic control of reflex cutaneous vasoconstriction in human aging.

    PubMed

    Greaney, Jody L; Alexander, Lacy M; Kenney, W Larry

    2015-10-01

    This Synthesis highlights a series of recent studies that has systematically interrogated age-related deficits in cold-induced skin vasoconstriction. In response to cold stress, a reflex increase in sympathetic nervous system activity mediates reductions in skin blood flow. Reflex vasoconstriction during cold exposure is markedly impaired in aged skin, contributing to the relative inability of healthy older adults to maintain core temperature during mild cold stress in the absence of appropriate behavioral thermoregulation. This compromised reflex cutaneous vasoconstriction in healthy aging can occur as a result of functional deficits at multiple points along the efferent sympathetic reflex axis, including blunted sympathetic outflow directed to the skin vasculature, reduced presynaptic neurotransmitter synthesis and/or release, and altered end-organ responsiveness at several loci, in addition to potential alterations in afferent thermoreceptor function. Arguments have been made that the relative inability of aged skin to appropriately constrict is due to the aging cutaneous arterioles themselves, whereas other data point to the neural circuitry controlling those vessels. The argument presented herein provides strong evidence for impaired efferent sympathetic control of the peripheral cutaneous vasculature during whole body cold exposure as the primary mechanism responsible for attenuated vasoconstriction. PMID:26272321

  9. Evaluation of Reflex (fomesafen) herbicide for watermelon in Oklahoma

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effective preemergence herbicides are needed for weed control in watermelon grown from transplants. Reflex (fomesafen) was found to be effective and to exhibit crop safety in southeast USA. Trials were conducted during 2011 and 2012 in southeast Oklahoma to determine if this product would be useful...

  10. Illustrations of the Analytic Memo as Reflexivity for Preservice Teachers

    ERIC Educational Resources Information Center

    Phillips, Donna Kalmbach; Carr, Kevin

    2007-01-01

    This study illustrates the use of analytic memos during the action research process as a space to support preservice teachers' emerging teacher identity and construction of practice through critical reflexivity. The authors reviewed 34 sets of analytic memos written by graduate preservice teachers by asking, "How are preservice teachers using the…

  11. Postoperative seizure outcome after corpus callosotomy in reflex epilepsy.

    PubMed

    Kwan, S Y; Wong, T T; Chang, K P; Yang, T F; Lee, Y C; Guo, W Y; Su, M S

    2000-03-01

    Flickering light and color patterns, reading, language, movement, decision making, eating, tapping and touching, hot water immersion and auditory stimulation can induce seizures in some epileptic patients. These are known as the "reflex epilepsies". The mechanism of reflex epilepsy is not clear. Recently, we performed anterior two-thirds corpus callosotomies in two reflex epilepsy patients (ages 12 and 14 years), with follow-up for more than three years. Patient 1 had Lennox-Gastaut syndrome with auditory-induced generalized atonic or tonic seizures (startle epilepsy), which decreased by 60% after callosotomy. Patient 2 had Lennox-Gastaut syndrome with somatosensory-induced generalized tonic seizures (tap epilepsy). He was seizure-free for one year immediately after callosotomy, but his seizures recurred with the same degree and frequency as before surgery. The nonsignificant postoperative seizure outcome suggests that the corpus callosum only plays a partial role in seizure generation. Our report also discusses the possible mechanisms of generation of reflex seizures. PMID:10746422

  12. 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…

  13. The Image Mirrored: Reflexivity and the Documentary Film

    ERIC Educational Resources Information Center

    Ruby, Jay

    1977-01-01

    Defines the concept of reflexivity as the structuring of a product in such a way that an audience assumes that the producer, the process of making, and the product are all part of a coherent whole, and contends that an audience needs to be made aware of these relationships. (MH)

  14. [Photo-reflex rheography and diagnosis of deep venous thrombosis].

    PubMed

    Stemmer, R; Marescaux, J; Furderer, C R

    1984-01-01

    Photo-reflex-rheography is a noninvasive method of measuring the filling of the subcutaneous venous plexuses. Daily recording during the pre- and post-operative period permits comparison of the amplitude of the curves and measurement of the time for refilling. Any diminution of these two parameters suggestive of a deep vein thrombosis is an indication for phlebography. PMID:6718506

  15. Emotions and Reflexivity in Feminised Education Action Research

    ERIC Educational Resources Information Center

    Burman, Erica

    2006-01-01

    The paper addresses contemporary relations between emotions, gender and feminist action research. Starting from analysis of the increasing emotionalisation of everyday life, it explores the quasi-feminist--or what the author calls "feminised"--forms of incitement to reflexive confession that are increasingly gaining favour within professional and…

  16. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered...

  17. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered...

  18. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered...

  19. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered...

  20. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered...

  1. Neurological presentations of hypothyroidism: the importance of slow relaxing reflexes.

    PubMed Central

    Wise, M P; Blunt, S; Lane, R J

    1995-01-01

    Neurological sequelae of hypothyroidism are well recognized and relatively common. Neurological symptoms occurring as a presenting feature of this illness are, however, uncommon. Here we report three patients who presented in such a way and in whom the diagnosis was only suspected because of slow relaxing reflexes. PMID:7636821

  2. Approaching Reflexivity through Reflection: Issues for Critical Management Education

    ERIC Educational Resources Information Center

    Hibbert, Paul

    2013-01-01

    This conceptual article seeks to develop insights for teaching reflexivity in undergraduate management classes through developing processes of critical reflection. Theoretical inferences to support this aim are developed and organized in relation to four principles. They are as follows: first, preparing and making space for reflection in the…

  3. Emotions and Reflexivity in Feminised Education Action Research

    ERIC Educational Resources Information Center

    Burman, Erica

    2006-01-01

    The paper addresses contemporary relations between emotions, gender and feminist action research. Starting from analysis of the increasing emotionalisation of everyday life, it explores the quasi-feminist--or what the author calls "feminised"--forms of incitement to reflexive confession that are increasingly gaining favour within professional and…

  4. 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…

  5. Transference, Counter-Transference, and Reflexivity in Intercultural Education

    ERIC Educational Resources Information Center

    Shim, Jenna Min

    2015-01-01

    The article addresses the contributions psychoanalytic theory, particularly its concepts of "transference and counter-transference," can make to our understanding of reflexivity in intercultural education (IE). After the introduction, the article is organized into three parts. The first part is a psychoanalytic discussion that focuses on…

  6. Shared Bimanual Tasks Elicit Bimanual Reflexes During Movement

    PubMed Central

    Mutha, Pratik K.

    2009-01-01

    Previous research has suggested distinct predictive and reactive control mechanisms for bimanual movements compared with unimanual motion. Recent studies have extended these findings by demonstrating that movement corrections during bimanual movements might differ depending on whether or not the task is shared between the arms. We hypothesized that corrective responses during shared bimanual tasks recruit bilateral rapid feedback mechanisms such as reflexes. We tested this hypothesis by perturbing one arm as subjects performed uni- and bimanual movements. Movements were made in a virtual-reality environment in which hand position was displayed as a cursor on a screen. During bimanual motion, we provided cursor feedback either independently for each arm (independent-cursor) or such that one cursor was placed at the average location between the arms (shared-cursor). On random trials, we applied a 40 N force pulse to the right arm 100 ms after movement onset. Our results show that while reflex responses were rapidly elicited in the perturbed arm, electromyographic activity remained close to baseline levels in the unperturbed arm during the independent-cursor trials. In contrast, when the cursor was shared between the arms, reflex responses were reduced in the perturbed arm and were rapidly elicited in the unperturbed arm. Our results thus suggest that when both arms contribute to achieving the task goal, reflex responses are bilaterally elicited in response to unilateral perturbations. These results agree with and extend recent suggestions that bimanual feedback control might be modified depending on task context. PMID:19793874

  7. 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

  8. How Abnormal Reflexes Influence Movements in Cerebral Palsy.

    ERIC Educational Resources Information Center

    Sellers, Jeanne Shanks

    Some of the more frequently observed reflex patterns in cerebral palsy are examined, and descriptions are given of how they affect movement. A chart outlines: (1) desirable movement patterns; (2) typical abnormal movement of the cerebral palsied child; (3) possible physical cause of abnormal movements; and (4) activities which may facilitate…

  9. Normal values of patellar and ankle tendon reflex latencies.

    PubMed

    Frijns, C J; Laman, D M; van Duijn, M A; van Duijn, H

    1997-02-01

    The clinical value of latency measurement of tendon reflexes in neurological patients has been reported by several authors. However, normal values are not readily comparable. In the present study, latencies and amplitudes of patellar (PTR) and ankle tendon reflexes (ATR) were measured at rest and after facilitation in 102 normal controls. A manually operated reflex hammer, tipped with electrically conductive rubber, ensured an immediate start of the sweep of the oscilloscope. Latencies showed a significant correlation with height (r = 0.70 for PTR and r = 0.72 for ATR, P < 0.0001) and to a lesser degree with age (r = 0.16 and r = 0.30, P < 0.0001). While amplitudes were highly variable, rendering them less useful for diagnostic purposes, latencies showed minimal intra-individual variability (CV 1.5 and 0.8%, respectively). Correlation of ATR-latency with the H-reflex latency of the soleus muscle was very high (r = 0.97, P < 0.0001). Comparison with three other hammer types yielded corresponding results with a hammer supplied with a piezo-electric element; however, significantly shorter latencies were found with a hammer with a microswitch, and with another hammer with a spring-contact, due to a delay from the tap on the tendon until the start of the sweep of the monitor. PMID:9107465

  10. Transference, Counter-Transference, and Reflexivity in Intercultural Education

    ERIC Educational Resources Information Center

    Shim, Jenna Min

    2015-01-01

    The article addresses the contributions psychoanalytic theory, particularly its concepts of "transference and counter-transference," can make to our understanding of reflexivity in intercultural education (IE). After the introduction, the article is organized into three parts. The first part is a psychoanalytic discussion that focuses on…

  11. Primitive reflexes and the determination of fetal presentation at birth.

    PubMed

    Bartlett, D; Piper, M; Okun, N; Byrne, P; Watt, J

    1997-05-28

    Ninety term breech-presenting singletons with birth weights greater than 2500 g and no congenital anomalies were matched with similar cephalic-presenting infants on gender and mode of delivery (n = 180). Thirteen primitive reflexes were examined at birth, 6 weeks and 3 and 5 months. No significant differences in the intensity of the asymmetrical tonic neck, symmetrical tonic neck, positive support tonic labyrinthine (prone and supine), segmental rolling (head-on-body and body-on-body), Galant, Moro, upper and lower extremity grasp, lower extremity placing and stepping reflexes were observed between these two groups of infants. Infants delivered vaginally, regardless of presentation, had weaker Moro reflexes at 5 months than infants delivered by cesarean section. The popular notion that precursors to early motor behaviors, such as the placing and stepping reflexes, are determinants of fetal presentation at the end of pregnancy is not supported by these results. Instead, spontaneously generated active whole body movements may be more significant influences of fetal orientation at the time of birth. PMID:9154417

  12. 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.

  13. Short-term poststimulatory response characteristics of the human acoustic stapedius reflex: monotic and dichotic stimulation.

    PubMed

    Cacace, A T; Margolis, R H; Relkin, E M

    1992-01-01

    Two experiments were performed to study short-term poststimulatory response characteristics of the human acoustic stapedius reflex in the time and intensity domains. In experiment 1, monotic magnitude-intensity functions (MIFs) were obtained for a 20-ms test stimulus preceded by a conditioning stimulus varying in duration (20, 50, 100, 500 ms) and level (-10, 0, +10 dB re: stapedius-reflex threshold) and temporally separated from the test stimulus by various interstimulus intervals (ISIs) (0, 20, 50, 100, 500 ms). Experiment 2 was similar in design except that conditioner and test stimuli were presented dichotically and fewer ISIs were used. Both experiments demonstrated that a prior conditioning stimulus produced significant increases in test-stimulus response magnitude. These poststimulatory effects were characterized by complex interactions among stimulus variables (conditioner duration, conditioner level, and interstimulus interval) with similar interactions occurring for both monotic and dichotic stimuli. A simple superposition effect of the responses to the conditioner and test stimulus does not account for the effect of prior stimulation since responses often exceeded the sum of the responses to the conditioner and the test stimulus alone. PMID:1737872

  14. 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

  15. Delayed latency of peroneal reflex to sudden inversion with ankle taping or bracing.

    PubMed

    Shima, N; Maeda, A; Hirohashi, K

    2005-01-01

    The purpose of the present study was to examine the effects of ankle taping and bracing based on the peroneal reflex in the hypermobile and normal ankle joints with and without history of ankle injury. Thirty-six ankle joints of 18 collegiate American football athletes with and without previous history of injury were studied. The angle of talar tilt (TT) was measured by stress radiograph for classifying normal (TT5 degrees ) ankles. They were tested with taping, bracing, and without any supports as a control. The latency of peroneus longus muscle was measured by a sudden inversion of 25 degrees using surface EMG signals. The results of the present study show no significant three-way Group (hypermobile or normal ankles) by History (previously injured or uninjured ankles) by Condition (control, taping, or bracing) interaction, while Condition main effect was significant (p<0.05). There were significant differences between control (80.8 ms) and taping (83.8 ms, p<0.01), between control and bracing (83.0 ms, p<0.05), but not between taping and bracing (p>0.05). In conclusion, ankle taping and bracing delayed the peroneal reflex latency not only for hypermobile ankles and/or injured ankle joints but also for intact ankle joints. PMID:16037891

  16. The influence of age on patellar reflex response in the dog.

    PubMed

    Levine, Jonathan M; Hillman, Robert B; Erb, Hollis N; deLahunta, Alexander

    2002-01-01

    The patellar tendon reflex is a clinical parameter commonly used to assess neurological status. Factors such as quadriceps muscle fiber composition, femur length, and patient age have been reported to influence total and fractionated reflex times in human beings. The purpose of this blinded, cross-sectional study was to examine the effect of age on the patellar reflex in the dog. Eighty-six dogs without evidence of neurological impairment or orthopedic disease of the stifle (eg, patellar luxation or cranial cruciate ligament rupture) were assigned to 1 of 2 groups on the basis of age: group 1, <10 years old (n = 72); or group 2, > or =10 years old (n = 14). Patellar reflexes were elicited in both pelvic limbs by a reflex hammer while the dog was in lateral recumbency. The reflex was scored as present or absent by a blinded individual. Two dogs in group I had reflexes absent in both limbs, 3 dogs in group 2 had reflexes absent in both limbs, and 1 dog in group 2 lacked a response in 1 limb. The proportion of dogs with absent patellar reflexes in group 2 (4 of 14, 95% CI, 8-58%) was significantly higher than the proportion of dogs with absent patellar reflexes in group 1 (2 of 72, 95% CI, 0-10%) (P < .006). Furthermore, dogs lacking at least 1 patellar reflex were older than those having both reflexes present (P = .04). Weight was not related to the presence of both reflexes (P = .49). These findings suggest that neurologically normal dogs may have an age-dependent decline in patellar reflex magnitude or a prolongation of total reflex time (TRT). PMID:12041652

  17. 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.

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

    PubMed Central

    Ferris, Daniel P; Aagaard, Per; Simonsen, Erik B; Farley, Claire T; Dyhre-Poulsen, Poul

    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. PMID:11136869

  19. 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

  20. Differential chemoreceptor reflex responses of adrenal preganglionic neurons.

    PubMed

    Cao, W H; Morrison, S F

    2001-12-01

    Adrenal sympathetic preganglionic neurons (ADR SPNs) regulating the chromaffin cell release of epinephrine (Epi ADR SPNs) and those controlling norepinephrine (NE ADR SPNs) secretion have been distinguished on the basis of their responses to stimulation in the rostral ventrolateral medulla, to glucopenia produced by 2-deoxyglucose, and to activation of the baroreceptor reflex. In this study, we examined the effects of arterial chemoreceptor reflex activation, produced by inhalation of 100% N(2) or intravenous injection of sodium cyanide, on these two groups of ADR SPNs, identified antidromically in urethane-anesthetized, artificially ventilated rats. The mean spontaneous discharge rates of 38 NE ADR SPNs and 51 Epi ADR SPNs were 4.4 +/- 0.4 and 5.6 +/- 0.4 spikes/s at mean arterial pressures of 98 +/- 3 and 97 +/- 3 mmHg, respectively. Ventilation with 100% N(2) for 10 s markedly excited all NE ADR SPNs (+222 +/- 23% control, n = 36). In contrast, the majority (40/48; 83%) of Epi ADR SPNs were unaffected or slightly inhibited by ventilation with 100% N(2) (population response: +6 +/- 10% control, n = 48). Similar results were obtained after injection of sodium cyanide. These observations suggest that the network controlling the spontaneous discharge of NE ADR SPNs is more sensitive to brief arterial chemoreceptor reflex activation than is that regulating the activity of Epi ADR SPNs. The differential responsiveness to activation of the arterial chemoreceptor reflex of the populations of ADR SPNs regulating epinephrine and norepinephrine secretion suggests that their primary excitatory inputs arise from separate populations of sympathetic premotor neurons and that a fall in arterial oxygen tension is not a major stimulus for reflex-mediated adrenal epinephrine secretion. PMID:11705767

  1. Function of sural nerve reflexes during human walking.

    PubMed

    Zehr, E P; Stein, R B; Komiyama, T

    1998-02-15

    1. The functions of ipsilateral cutaneous reflexes were studied with short trains of stimuli presented pseudorandomly to the sural nerve during human walking. Electromyograms (EMG) of lower (tibialis anterior (TA), soleus, lateral (LG) and medial (MG) gastrocnemius) and upper leg (vastus lateralis and biceps femoris) muscles were recorded, together with ankle, knee and hip joint angles. Net reflex EMG responses were quantified in each of the sixteen parts of the step cycle. The kinematic measurements included ankle eversion- inversion, and ankle, knee and hip flexion-extension. 2. The function of the sural reflexes depended upon the part of the step cycle in which the nerve was stimulated and the intensity of stimulation. During stance, reflexes in MG and TA muscles in response to a medium intensity of stimulation (1.9 x radiating threshold, x RT) were closely associated with ankle eversion and dorsiflexion responses, respectively. These responses could assist in accommodation to uneven terrain that applies pressure to the lateral side of the foot (sural innervation area). Non-noxious, high intensity (2.3 x RT) stimulation resulted in strong suppression of LG and MG during stance which was correlated to a small reduction in ankle plantarflexion. At this higher intensity the response would function to prevent the foot from moving more forcefully onto a potentially harmful obstacle. 3. During swing, ankle dorsiflexion increased and was significantly correlated to the net TA EMG response after both medium and high intensity stimulation. Knee flexion was increased throughout swing at both intensities of stimulation. These responses may serve in an avoidance response in which the swing limb is brought past an obstacle without destabilizing contact. 4. The net EMG and kinematic responses suggest that cutaneous reflexes stabilize human gait against external perturbations produced by an uneven surface in stance or obstacles encountered during swing. PMID:9490858

  2. Ipsi- and contralateral H-reflexes and V-waves after unilateral chronic Achilles tendon vibration.

    PubMed

    Lapole, Thomas; Canon, Francis; Pérot, Chantal

    2013-09-01

    Chronic Achilles tendon vibration has previously shown its effectiveness in improving plantar flexor's strength and activation capacities. The present study investigated the related neural mechanisms by analyzing H-reflexes and V-waves of the soleus (SOL) and gastrocnemii (GM gastrocnemius medialis; GL gastrocnemius lateralis) muscles under maximal isometric plantar flexion. Moreover, recordings were conducted bilaterally to address potential crossed effects. 11 subjects were engaged in this study. Maximal voluntary contraction and superimposed H-reflexes and V-waves were quantified in both legs at baseline (PRE) and 2 weeks later to verify repeatability of data (CON). Then, subjects were retested after 14 days of daily unilateral Achilles tendon vibration (VIB; 1 h per day; frequency: 50 Hz). No changes were reported between PRE and CON data. In the VIB condition, there was an increase in MVC for both the vibrated (+9.1 %; p = 0.016) and non-vibrated (+10.2 %; p = 0.009) legs. The H-reflex increased by a mean 25 % in the vibrated SOL (p < 0.001), while it remained unchanged for the contralateral side (p = 0.531). The SOL V-wave also increased in the vibrated limb (+43.3 %; p < 0.001), as well as in the non-vibrated one (+41.9 %; p = 0.006). Furthermore, the GM V-wave increased by 37.8 % (p = 0.081) in the vibrated side and by 39.4 % (p = 0.03) in the non-vibrated side. However, no changes were reported for the GL muscles. While the present study confirmed the strength gains induced by chronic Achilles tendon vibration, the results indicated a cross-education phenomenon with differences in neural adaptations between the vibrated leg and non-vibrated leg. PMID:23652708

  3. Understanding the pathophysiology of reflex epilepsy using simultaneous EEG-fMRI.

    PubMed

    Sandhya, Manglore; Bharath, Rose Dawn; Panda, Rajanikant; Chandra, S R; Kumar, Naveen; George, Lija; Thamodharan, A; Gupta, Arun Kumar; Satishchandra, P

    2014-03-01

    Measuring neuro-haemodynamic correlates in the brain of epilepsy patients using EEG-fMRI has opened new avenues in clinical neuroscience, as these are two complementary methods for understanding brain function. In this study, we investigated three patients with drug-resistant reflex epilepsy using EEG-fMRI. Different types of reflex epilepsy such as eating, startle myoclonus, and hot water epilepsy were included in the study. The analysis of EEG-fMRI data was based on the visual identi?cation of interictal epileptiform discharges on scalp EEG. The convolution of onset time and duration of these epilepsy spikes was estimated, and using these condition-specific effects in a general linear model approach, we evaluated activation of fMRI. Patients with startle myoclonus epilepsy experienced epilepsy in response to sudden sound or touch, in association with increased delta and theta activity with a spike-and-slow-wave pattern of interictal epileptiform discharges on EEG and fronto-parietal network activation pattern on SPECT and EEG-fMRI. Eating epilepsy was triggered by sight or smell of food and fronto-temporal discharges were noted on video-EEG (VEEG). Similarly, fronto-temporo-parietal involvement was noted on SPECT and EEG-fMRI. Hot water epilepsy was triggered by contact with hot water either in the bath or by hand immersion, and VEEG showed fronto-parietal involvement. SPECT and EEG fMRI revealed a similar fronto-parietal-occipital involvement. From these results, we conclude that continuous EEG recording can improve the modelling of BOLD changes related to interictal epileptic activity and this can thus be used to understand the neuro-haemodynamic substrates involved in reflex epilepsy. PMID:24691294

  4. Interaction between descending input and thoracic reflexes for joint coordination in cockroach: I. descending influence on thoracic sensory reflexes.

    PubMed

    Mu, Laiyong; Ritzmann, Roy E

    2008-03-01

    Tethered cockroaches turn from unilateral antennal contact using asymmetrical movements of mesothoracic (T2) legs (Mu and Ritzmann in J Comp Physiol A 191:1037-1054, 2005). During the turn, the leg on the inside of the turn (the inside T2 leg) has distinctly different motor patterns from those in straight walking. One possible neural mechanism for the transformation from walking to inside leg turning could be that the descending commands alter a few critical reflexes that start a cascade of physical changes in leg movement or posture, leading to further alterations. This hypothesis has two implications: first, the descending activities must be able to influence thoracic reflexes. Second, one should be able to initiate the turning motor pattern without descending signals by mimicking a point farther down in the reflex cascade. We addressed the first implication in this paper by experiments on chordotonal organ reflexes. The activity of depressor muscle (Ds) and slow extensor tibia muscle (SETi) was excited and inhibited by stretching and relaxing the femoral chordotonal organ. However, the Ds responses were altered after eliminating the descending activity, while the SETi responses remain similar. The inhibition to Ds activity by stretching the coxal chordotonal organ was also altered after eliminating the descending activity. PMID:18094976

  5. Analysis of contributions of acetylcholine and tachykinins to neuro-neuronal transmission in motility reflexes in the guinea-pig ileum.

    PubMed Central

    Johnson, P. J.; Bornstein, J. C.; Yuan, S. Y.; Furness, J. B.

    1996-01-01

    1. The roles of acetylcholine (ACh) and tachykinins in neuro-neuronal transmission during ascending excitatory and descending inhibitory reflexes were studied by recording intracellular reflex responses of the circular muscle to physiological stimuli. Experiments were carried out in opened segments of guinea pig ileum in an organ bath that was partitioned so that three regions could be independently exposed to drugs. 2. Ascending excitatory reflexes evoked by either distension from the serosal side or compression of the mucosa were depressed by 55% and 85%, respectively, in the presence of hexamethonium (200 microM) and by 30% and 45%, respectively, by a desensitizing concentration of the selective NK3 receptor agonist, senktide (1 microM), in the chamber in which reflexes were initiated. Together, hexamethonium and senktide abolished responses to compression. A residual response to distension persisted. This was abolished by hyoscine (1 microM). 3. Hexamethonium (200 microM) abolished ascending reflexes when applied to the region between the stimulus and the recording sites, or to the recording chamber. 4. Descending reflex responses were reduced by 35% by synaptic blockade in the stimulus chamber with physiological saline containing 0.1 mM Ca2+ plus 10 mM Mg2+. Senktide (1 microM) in the stimulus chamber reduced distension reflexes to the same extent as synaptic blockade, whereas hexamethonium (200 microM) and hyoscine (1 microM) depressed responses by less than 20%. Responses to compression were reduced by 40% by senktide alone, while senktide and hexamethonium together reduced responses by 60%, an effect similar to synaptic blockade. Under these conditions, hyoscine in the stimulus chamber restored reflexes evoked by distension, but did not alter those evoked by mucosal compression. 5. Total synaptic blockade in the intermediate chamber, between stimulus and recording sites, reduced descending reflex responses by more than 90%. In contrast, hexamethonium (200 microM) had no effect and hyoscine (1 microM) reduced only the responses to distension (by 30%). Senktide (1 microM) depressed responses to both stimuli by approximately 80%. 6. Application of hexamethonium (200 microM) to the recording chamber depressed descending reflex responses to distension applied in the near stimulation chamber by 15%, but had no effect on responses to compression in the near chamber or to either stimulus applied in the far chamber. 7. Descending reflexes evoked by near chamber stimuli were unaffected by hyoscine (1 microM) or senktide (1 microM) applied to the recording chamber; hyoscine enhanced reflexes evoked by compression in the far chamber by 50%. 8. For the ascending excitatory reflex pathway, it is concluded that transmission from sensory neurones is mediated by ACh acting via both nicotinic and muscarinic receptors, and by tachykinins acting at NK3 receptors. Transmission from ascending interneurones appears to be predominantly via nicotinic receptors. The descending inhibitory pathways are more complex, and while transmission from sensory neurones involves nicotinic, muscarinic and NK3 receptor-dependent components, transmission from descending interneurones to inhibitory motor neurones is neither cholinergic nor due to tachykinins acting via NK3 receptors. Images Figure 8 PMID:8799571

  6. Dynamic regulation of the siphon withdrawal reflex of Aplysia californica in response to changes in the ambient tactile environment.

    PubMed

    Fischer, T M; Yuan, J W; Carew, T J

    2000-12-01

    The state of an animal's environment can be viewed as a source of information that can be used to regulate both ongoing and future behavior. The present work examined how the ambient environment can regulate the Aplysia siphon withdrawal reflex (SWR) by changing the environment between calm and turbulent. Results indicate that the SWR is dynamically regulated on the basis of variations in external conditions, so that responsiveness (measured as both reflex duration and threshold) is matched to the state of the environment. Prior exposure to a noxious stimulus (tailshock) has selective effects on this regulation, suggesting the existence of multiple regulatory mechanisms. Further, neurophysiological correlates to behavioral observations were measured in sensory and motor neurons. This will allow for a detailed cellular analysis of environmental information-processing in this system. PMID:11142653

  7. Retention of primitive reflexes and delayed motor development in very low birth weight infants.

    PubMed

    Marquis, P J; Ruiz, N A; Lundy, M S; Dillard, R G

    1984-06-01

    Primitive reflexes and motor development were evaluated in 127 very low birth weight (VLBW) infants (birth weight less than 1501 grams) at four months corrected age. The asymmetrical tonic neck reflex, tonic labyrinth reflex, and Moro reflex were assessed for each child. The ability of each child to reach (obtain a red ring) and roll were observed. The child's performance on the gross motor scale of the Denver Development Screening Test was recorded. Thirty-seven term infants were administered identical evaluations at four months of age. The VLBW infants retained stronger primitive reflexes and exhibited a significantly higher incidence of motor delays than term infants. Significant correlations existed between the strength of the primitive reflexes and early motor development for VLBW infants. This study confirms a high incidence of motor delays among VLBW infants and demonstrates a clear association between retained primitive reflexes and delayed motor development in VLBW infants. PMID:6736257

  8. [Establishment of H reflex model in mice with minimal insult and measurement of nerve conduction velocity].

    PubMed

    Ren, Hao; Zhou, Rui-Ling; Zhou, Chong-Tan

    2012-08-25

    The aim of the present study was to establish a minimally invasive H reflex model in mice for the benefit of the research of clinical spinal cord injury and related diseases. Minimally invasive surgery was performed in hind limb of Kunming mouse under light anesthesia. The skin was incised at the point of one-third of the distance from greater trochanter to the base of the cauda. A pair of fine copper conductors were inserted into the shallow muscle using a syringe needle. After the needles were withdrawed, the retained conductors were ligated and fixed with the tissues surrounding the sciatic nerve as the first pair of stimulating electrodes. Another pair of conductors were inserted and fixed in medial malleolus close to the tibial nerve as the second stimulating electrodes. Copper conductor was inserted passing the skin above the proximal end of the metatarsal and fixed as the recording electrode. The reference electrode was placed at the walking pad in the base of the big toe using the same method. Electromyography (EMG) was used to record M and H waves in planta pedis muscles. The stimulus was a square wave with a width of 0.2 ms and frequency of 0.3 Hz. The latency time of the M and H waves which were induced from the two pairs of stimulating electrodes was recorded. Nerve conduction velocity (NCV) was then calculated from the distance between the cathodes of the stimulating electrodes and the latency time difference of M or H waves. The result showed the achievement ratios of H reflex induction were 92.73% and 81.82% in sciatic and tibial nerves, respectively. The latency time of H wave was about 7~10 ms. Motor nerve conduction velocity (MNCV) obtained was (25.84 ± 4.70) m/s (n = 35), while sensory nerve conduction velocity (SNCV) was (31.45 ± 7.30) m/s (n = 35). The method established in the present paper is simple to practice, does slight harm to the animal, and can produce waveforms with little interference. With these advantages, the method can be applied for the study of the latency of H reflex, and it is suitable for the researches which demands good physical condition of experimental animal during H reflex study. This model can also be applied to the detection of SNCV and MNCV. PMID:22907309

  9. 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

  10. Healthy and pathological cerebellar Spiking Neural Networks in Vestibulo-Ocular Reflex.

    PubMed

    Antonietti, Alberto; Casellato, Claudia; Geminiani, Alice; D'Angelo, Egidio; Pedrocchi, Alessandra

    2015-08-01

    Since the Marr-Albus model, computational neuroscientists have been developing a variety of models of the cerebellum, with different approaches and features. In this work, we developed and tested realistic artificial Spiking Neural Networks inspired to this brain region. We tested in computational simulations of the Vestibulo-Ocular Reflex protocol three different models: a network equipped with a single plasticity site, at the cortical level; a network equipped with a distributed plasticity, at both cortical and nuclear levels; a network with a pathological plasticity mechanism at the cortical level. We analyzed the learning performance of the three different models, highlighting the behavioral differences among them. We proved that the model with a distributed plasticity produces a faster and more accurate cerebellar response, especially during a second session of acquisition, compared with the single plasticity model. Furthermore, the pathological model shows an impaired learning capability in Vestibulo-Ocular Reflex acquisition, as found in neurophysiological studies. The effect of the different plasticity conditions, which change fast and slow dynamics, memory consolidation and, in general, learning capabilities of the cerebellar network, explains differences in the behavioral outcome. PMID:26736803

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

    PubMed

    Dicpinigaitis, Peter V

    2014-10-01

    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

  12. Simulation of reflex late decelerations in labor with a mathematical model.

    PubMed

    van der Hout-van der Jagt, M Beatrijs; Oei, S Guid; Bovendeerd, Peter H M

    2013-01-01

    Fetal welfare during labor and delivery is commonly monitored through the cardiotocogram (CTG), the combined registration of uterus contractions and fetal heart rate (FHR). From the CTG, the fetal oxygen state is estimated as the main indicator of the fetal condition, but this estimate is difficult to make, due to the complex relation between CTG and oxygen state. Mathematical models can be used to assist in the interpretation of the CTG, since they enable quantitative modeling of the flow of events through which uterine contractions affect fetal oxygenation and FHR. We propose a mathematical model to simulate reflex 'late decelerations', i.e. variations in FHR originating from uteroplacental flow reduction during uterine contractions and mediated by the baroreflex and the chemoreflex. Results for the uncompromised fetus show that partial oxygen pressures reduce in relation to the strength and duration of the contraction. Above a certain threshold, hypoxemia will evoke a late deceleration. Results for uteroplacental insufficiency, simulated by reduced uterine blood supply or reduced placental diffusion capacity, demonstrated lower baseline FHR and smaller decelerations during contraction. Reduced uteroplacental blood volume was found to lead to deeper decelerations only. The model response in several nerve blocking simulations was similar to experimental findings by Martin et al. [18], indicating a correct balance between vagal and sympathetic reflex pathways. PMID:22840604

  13. Vestibular-evoked postural reactions in man and modulation of transmission in spinal reflex pathways.

    PubMed Central

    Iles, J F; Pisini, J V

    1992-01-01

    1. The effects of galvanic stimulation of the vestibular apparatus (with electrodes on the mastoid processes) have been studied in standing human subjects. With the head turned to one side, subjects swayed towards the anode. 2. Forwards sway was preceded by electromyographic (EMG) activity in quadriceps and tibialis anterior muscles. Backwards sway was preceded by EMG activity in soleus and hamstring muscles. 3. Using the method of H reflex conditioning, forward sway was found to be preceded by inhibition of soleus motoneurones. 4. Interaction between the vestibular-evoked inhibition of soleus motoneurones preceding forwards sway and peripheral reflex inhibition was examined by a spatial facilitation method. 5. Interaction was found between vestibular-evoked inhibition and Ia reciprocal, group I non-reciprocal and group Ia-Ia presynaptic inhibitory pathways. It is concluded that vestibular signals converge on spinal interneurones subserving these inhibitory actions. 6. A 'decoupling' of soleus motoneurons and soleus-coupled Renshaw cells was found in the period of soleus activation preceding backwards sway. PMID:1336553

  14. 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.

  15. '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.

  16. Blink reflex latency after exposure to trichloroethylene in well water

    SciTech Connect

    Feldman, R.G.; Chirico-Post, J.; Proctor, S.P.

    1988-03-01

    The electrophysiological measurement of the blink reflex (BR) can quantify the conduction latency in the reflex arc involving the Vth (trigeminal) and VIIth (facial) cranial nerves. We measured the electrophysiological BR in a population (N = 21), which had alleged chronic exposure to trichloroethylene (TCE) through the public drinking water at levels 30-80 times higher than the Environmental Protection Agency (EPA) Maximum Contamination Level (MCL). A highly significant difference was observed in the conduction latency means of the BR components (p less than .0001), when the study population was compared with laboratory controls (N = 27). This difference suggests a subclinical alteration of the Vth cranial nerve function due to chronic, environmental exposure to TCE.

  17. A model of reflex tracheal constriction in the dog.

    PubMed Central

    Allott, C. P.; Evans, D. P.; Loveday, B. E.; Marshall, P. W.

    1980-01-01

    1 A tracheal pouch with its nerve and blood supply intact has been prepared in situ in dogs. 2 Mechanical stimulation of the upper airways in dogs anaesthetized with chloralose induced a consistent increase in pouch pressure which was abolished by bilateral vagal section. 3 The response of the pouch following mechanical stimulation of the airways was abolished by intravenous pentobarbitone, atropine, administered systemically or when present in the pouch, and tetracaine, applied to the stimulus area or when present in the pouch. 4 Salbutamol had no inhibitory effects on the response regardless of its route of administration. 5 These results suggest that the increase in pouch pressure following mechanical stimulation of the upper airways is mediated by a vagal reflex arc. 6 The technique may distinguish between drugs the site of action of which is at the afferent or efferent end of this reflex arc. PMID:7437649

  18. 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

  19. Results of the REFLEX (Return Flux Experiment) Flight Mission

    NASA Technical Reports Server (NTRS)

    Pepin, R. O. (Compiler); Mauersberger, Konrad; Johnson, Bradford W.; Manning, Heidi K.

    1997-01-01

    The numerous problems occurring in this first flight of the REFLEX experiment, both in the spacecraft and with the instrument package, seriously constrained the acquisition and analysis of data and severely limited the interpretation of the data that were obtained. Of these, the ambient helium measurements appear to be the most promising. They are summarized and discussed in Appendix A. Further analyses could be attempted to establish the correct values for the energy centers as they varied during the mission. In addition, an extensive laboratory recalibration on a high-speed beam system could in principle provide corrections to be used in analyzing and interpreting the returned data set. The unknown malfunction which generated the energy drift needs to be understood and corrected before the REFLEX experiment is reflown; some hardware modification, or at least retuning, is likely to be required.

  20. The afferent volleys responsible for spinal proprioceptive reflexes in man

    PubMed Central

    Burke, David; Gandevia, Simon C.; McKeon, Brian

    1983-01-01

    1. To define the neural volleys responsible for the Achilles tendon jerk and the H reflex, muscle afferent activity was recorded using micro-electrodes inserted percutaneously into appropriate fascicles of the tibial nerve in the popliteal fossa. 2. The response of soleus muscle afferents to tendon percussion consisted of a dispersed volley, starting 3·5-7·0 ms after percussion, increasing to a peak over 6·5-11·0 ms, and lasting 25-30 ms, depending on the strength of percussion. Electrical stimuli to the sciatic nerve at a level adequate to evoke an H reflex but subthreshold for the M wave produced a more synchronized volley, the fastest fibres of which had conduction velocities of 62-67 m/s, and the slowest 36-45 m/s. 3. The wave of acceleration produced by percussion subthreshold for the ankle jerk spread along the skin at over 150 m/s. Midway between the bellies of the gastrocnemii it consisted of a damped oscillation with four to five separate phases and maximum amplitude approximately one-twentieth of that recorded on the Achilles tendon. 4. With ten primary spindle endings, tendon percussion subthreshold for the ankle jerk elicited two to five spike discharges per tap, the shortest interspike intervals being 4-7 ms. Tendon percussion elicited single discharges from two Golgi tendon organs, and altered the discharge pattern of a single secondary spindle ending. The degree of dispersion of the multi-unit muscle afferent volley can be explained by the pattern of discharge of primary spindle endings. 5. Percussion on the Achilles tendon evoked crisp afferent volleys in recordings from nerve fascicles innervating flexor hallucis longus, tibialis posterior, the intrinsic muscles of the foot and the skin of the foot. Electrical stimuli delivered to the tibial nerve in the popliteal fossa at a level sufficient for the H reflex of soleus produced either a volley in muscle afferents from the intrinsic muscles of the foot or a volley in cutaneous afferents from the foot. 6. For comparable stimuli in the two positions, the H reflex was inhibited but the Achilles tendon jerk enhanced when the ankle was dorsiflexed from 105° to 90°. 7. The duration of the rise times of the excitatory post-synaptic potentials (e.p.s.p.s) produced in soleus motoneurones by electrical stimulation, and by tendon percussion subthreshold for the H reflex and the ankle jerk respectively, was estimated from post-stimulus time histograms of the discharge of voluntarily activated single motor units in soleus. The mean e.p.s.p. rise times were 1·9 ms for electrical stimulation and 6·6 ms for tendon percussion. There was evidence that the duration of the electrically evoked e.p.s.p. was curtailed by an inhibitory post-synaptic potential (i.p.s.p.) of only slightly longer latency than the e.p.s.p. 8. The mechanically induced and electrically induced afferent volleys are not homogeneous volleys in group I a afferents from triceps surae. The afferent volleys differ in so many respects that it is probably invalid to compare the H reflex and tendon jerk as a measure of fusimotor activity. It is suggested that neither reflex can be considered a purely monosynaptic reflex. PMID:6887033

  1. Multiple scattering of electrons in the reflex triode

    SciTech Connect

    Creedon, J.M. )

    1990-12-01

    Analytical theories and Monte Carlo calculations are used to treat the scattering and energy loss of electrons in the anode of a reflex triode. The solution of this scattering problem is combined with the equations for particle flow in vacuum to give a quantitative theory of triode operation. It is now possible to calculate several important properties of this device. These include the operating voltage in the constant voltage mode, the ratio of ion-to-electron current and the ion transit time.

  2. Reflex sympathetic dystrophy in the hands: clinical and scintigraphic criteria

    SciTech Connect

    Holder, L.E.; Mackinnon, S.E.

    1984-08-01

    In an attempt to establish specific scintigraphic criteria for the reflex sympathetic dystrophy syndrome (RSD) as defined by a group of specialized hand surgeons, 145 consecutive patients, 23 of whom had clinical RSD, underwent three phase radionuclide bone scanning (TPBS). Specific patterns for positive radionuclide angiogram, blood pool, and delayed images were established. The delayed images were sensitive (96%), specific (97%), and had a valuable negative predictive value (99%). It was concluded that TPBS could provide an objective marker for RSD.

  3. 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

  4. Medial olivocochlear efferent reflex inhibition of human cochlear nerve responses.

    PubMed

    Lichtenhan, J T; Wilson, U S; Hancock, K E; Guinan, J J

    2016-03-01

    Inhibition of cochlear amplifier gain by the medial olivocochlear (MOC) efferent system has several putative roles: aiding listening in noise, protection against damage from acoustic overexposure, and slowing age-induced hearing loss. The human MOC reflex has been studied almost exclusively by measuring changes in otoacoustic emissions. However, to help understand how the MOC system influences what we hear, it is important to have measurements of the MOC effect on the total output of the organ of Corti, i.e., on cochlear nerve responses that couple sounds to the brain. In this work we measured the inhibition produced by the MOC reflex on the amplitude of cochlear nerve compound action potentials (CAPs) in response to moderate level (52-60 dB peSPL) clicks from five, young, normal hearing, awake, alert, human adults. MOC activity was elicited by 65 dB SPL, contralateral broadband noise (CAS). Using tympanic membrane electrodes, approximately 10 h of data collection were needed from each subject to yield reliable measurements of the MOC reflex inhibition on CAP amplitudes from one click level. The CAS produced a 16% reduction of CAP amplitude, equivalent to a 1.98 dB effective attenuation (averaged over five subjects). Based on previous reports of efferent effects as functions of level and frequency, it is possible that much larger effective attenuations would be observed at lower sound levels or with clicks of higher frequency content. For a preliminary comparison, we also measured MOC reflex inhibition of DPOAEs evoked from the same ears with f2's near 4 kHz. The resulting effective attenuations on DPOAEs were, on average, less than half the effective attenuations on CAPs. PMID:26364824

  5. Cardioinhibitory reflex due to a karate kick: a case report.

    PubMed

    de Froidmont, Sébastien; Lobrinus, Johannes Alexander; Michaud, Katarzyna; Palmiere, Cristian; Augsburger, Marc-Pierre; Mangin, Patrice; Grabherr, Silke

    2015-06-01

    This article describes the case of a 17-year-old adolescent boy who received a foot kick in the trunk area from an expert in karate. He presented with immediate cardiocirculatory arrest. After a prolonged resuscitation, he was transferred to a hospital where he died 5 days later without ever regaining consciousness. Postmortem investigations including autopsy, radiology, histology, toxicology, and postmortem chemistry were performed that showed signs of multiple organ failure, an acute hemorrhage in the region of the celiac plexus, and signs of medical resuscitation. No preexisting disease, particularly those concerning the heart, was objectified. The cause of death was attributed to multiple organ failure after a prolonged cardiocirculatory arrest. Concerning the origin of the cardiac arrest, 2 hypotheses were considered-a cardioinhibitory reflex and a cardiac contusion (commotio cordis). Because of the presence of traumatic lesions in the celiac plexus, the first hypothesis was finally submitted. This case is reported because rare cases of sudden death from celiac reflex are described in the literature where it is almost impossible to find references with accurate documentation. The presented case confirms the importance of detailed documentation of the circumstances and postmortem investigations to establish a diagnosis of death due to cardioinhibitory reflex. PMID:25881816

  6. 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

  7. An overset grid method for the study of reflex tearing.

    PubMed

    Maki, K L; Braun, R J; Driscoll, T A; King-Smith, P E

    2008-09-01

    We present an overset grid method to simulate the evolution of human tear film thickness subject to reflex tearing. The free-surface evolution is governed by a single fourth-order non-linear equation derived from lubrication theory with specified film thickness and volume flux at each end. The model arises from considering the limiting case where the surfactant is strongly affecting the surface tension. In numerical simulations, the overset grid is composed of fine boundary grids near the upper and lower eyelids to capture localized capillary thinning referred to as 'black lines' and a Cartesian grid covers the remaining domain. Numerical studies are performed on a non-linear test problem to confirm the accuracy and convergence of the scheme. The computations on the tear film model show qualitative agreement with in vivo tear film thickness measurements. Furthermore, the role of the black lines in the presence of tear supply from the lid margins, reflex tearing, was found to be more subtle than a barrier to tear fluid flow between the anterior of the eye and the meniscus at the lid margin. During reflex tearing, tears may flow through the region normally containing the black line and drift down over the cornea under the influence of gravity. PMID:18628245

  8. Stimulus-induced reflex epileptic spasms in 5p- syndrome.

    PubMed

    Shirai, Kentaro; Saito, Yoshiaki; Yokoyama, Atushi; Nishimura, Yoko; Tamasaki, Akiko; Maegaki, Yoshihiro

    2016-02-01

    Here we describe two patients with 5p- syndrome who suffered from epilepsy characterised by stimulus-induced epileptic spasms manifesting as head nodding. In patient 1, a series of spasms were exclusively triggered by eating, and were associated with diffuse high-voltage slow waves on ictal EEG, particularly presenting as a positive slow potential at the left mid-temporal area. Clusters of sharp waves with negative polarity emerged in the same area during the inter-spasm periods during eating. In patient 2, spasms were provoked by either eating or micturition. Ictal EEG of clustered spasms after micturition showed positive slow or triphasic waves, which correlated with each spasm, over the bifrontal and vertex areas. These findings suggest that the focal cortical areas act as trigger regions in reflex epilepsies, and that a spasm-generator responsible for the execution of reflex spasms exists either in other cortical areas or in the subcortical structures. Although epilepsy is an unusual complication of 5p- syndrome, this syndrome may have a propensity to develop reflex epilepsy, particularly epileptic spasms. However, identification of responsible genes and their roles in this phenotype requires further investigations. PMID:26298410

  9. Mechanoreceptors and reflex arc in the feline shoulder.

    PubMed

    Solomonow, M; Guanche, C; Wink, C; Knatt, T; Baratta, R V; Lu, Y

    1996-01-01

    A reflex arc from the glenohumeral capsule to the biceps, infraspinatus, supraspinatus, and subscapular muscles was shown in a feline preparation. Branches of the suprascapular and subscapular nerves terminating in the capsule were identified and then stimulated with a 100 microseconds supramaximal pulse at 10 pulses per second. Stimulation of the suprascapular articular nerve elicited electromyographic discharge in the biceps and infraspinatus muscles, whereas stimulation of the subscapular articular nerve elicited electromyographic discharge in the biceps, subscapularis, infraspinatus, and supraspinatus muscles. When the articular nerves were transected between their emergence from the main nerve trunk and the stimulation electrodes, the electromyographic discharge was abolished confirming the afferent nature of the nerves. The mean time delay ( +/- SD) from application of the stimulus to the peak of the recorded electromyographic activity was 3.2 +/- 0.27 msec. Anatomic dissection and staining of the capsule segments where the articular nerves terminated revealed mechanoreceptors consisting primarily of free nerve endings and Golgi tendon organs, Ruffini's endings, and pacinian corpuscles. The existence of a ligamento-muscular reflex arc in the glenohumeral joint extends the concept of passive and active restraints of a joint by virtue of the synergy between ligaments and muscles. That such a reflex exists may advocate modification of surgical repairs of the capsule, leading to preservation of as many neurologic structures as possible; it may also form the foundation for new postsurgical therapeutic modalities. PMID:8742878

  10. Reflex seizures, traits, and epilepsies: from physiology to pathology.

    PubMed

    Koepp, Matthias J; Caciagli, Lorenzo; Pressler, Ronit M; Lehnertz, Klaus; Beniczky, Sándor

    2016-01-01

    Epileptic seizures are generally unpredictable and arise spontaneously. Patients often report non-specific triggers such as stress or sleep deprivation, but only rarely do seizures occur as a reflex event, in which they are objectively and consistently modulated, precipitated, or inhibited by external sensory stimuli or specific cognitive processes. The seizures triggered by such stimuli and processes in susceptible individuals can have different latencies. Once seizure-suppressing mechanisms fail and a critical mass (the so-called tipping point) of cortical activation is reached, reflex seizures stereotypically manifest with common motor features independent of the physiological network involved. The complexity of stimuli increases from simple sensory to complex cognitive-emotional with increasing age of onset. The topography of physiological networks involved follows the posterior-to-anterior trajectory of brain development, reflecting age-related changes in brain excitability. Reflex seizures and traits probably represent the extremes of a continuum, and understanding of their underlying mechanisms might help to elucidate the transition of normal physiological function to paroxysmal epileptic activity. PMID:26627365

  11. Skeletal muscle tone and the misunderstood stretch reflex.

    PubMed

    Davidoff, R A

    1992-05-01

    This review presents a revision of long-accepted tenets regarding the genesis of muscle tone in humans. Most discussions liken muscle tone in humans to the reflex tone described by Sherrington in decerebrate animals. That tradition presumes that muscle tone is fully determined by the monosynaptic stretch reflex, that tonic fusimotor activity is necessary for its production in normal humans, and that tonic muscle tone in antigravity leg muscles is responsible for the maintenance of posture. Data reviewed here show that nonreflex, mechanical mechanisms are involved in the maintenance of resting muscle tone; that spinal cord reflex responses are not stereotyped responses, but depend upon the ongoing activity in interneurons upon which inputs from a variety of peripheral sensory receptors and descending fiber systems converge; that long-latency transcortical responses are elicited when a muscle is stretched, and these responses effectively deal with large displacements; and that inertial components and viscoelastic muscle forces can counterbalance small amounts of body sway during quiet standing. In sum, the response to muscle stretch is not fixed and inflexible, but can be adjusted according to the demands of the moment. PMID:1579249

  12. The glenohumeral-biceps reflex in the feline.

    PubMed

    Knatt, T; Guanche, C; Solomonow, M; Lu, Y; Baratta, R; Zhou, B H

    1995-05-01

    The existence of a reflex arc from the anterior aspects of the glenohumeral capsule to the long head of the biceps was determined in a feline. A single articular branch of the musculocutaneous nerve terminating in the capsule was identified and stimulated with 100 microseconds supramaximal pulse train at 10 pulses per second. It was shown tht stimulation of the musculocutaneous articular nerve elicited myoelectric discharge in the biceps muscle. Transection of the articular nerve just distal to its emergence from the main trunk of the musculocutaneous nerve abolished the myoelectric discharge in the biceps, confirming the afferent nature of this articular nerve. The mean (+/- standard deviation) time delay from the application of the stimulus to the articular nerve to the recording of the corresponding myoelectric discharge in the biceps was 2.7 (+/- 0.3) milliseconds. The existence of a reflex arc from the capsule to the biceps confirms and extends the concept of passive (ligaments) and active (muscles) restraints of a joint and the synergy between them toward maintaining shoulder stability. If demonstrated in the human, such a reflex may have significant implications in modification of surgical procedures and the design of new rehabilitation modalities for treatment of shoulder defects. PMID:7634642

  13. Reflex Epilepsy Induced by Playing Oriental Card or Board Games

    PubMed Central

    Choi, Eun Jung; Kang, Joong Koo

    2006-01-01

    Background and Purpose There are currently few studies on clinical profiles of reflex epilepsy induced by thinking and spatial tasks. We studied the clinical characteristics of reflex epilepsy induced by playing oriental card and board games. Methods This study included 17 patients who presented with seizures that occur predominantly while playing games. We collected clinical data via protocol-based interviews. EEGs and brain MRI were performed. Results All of the subjects were men, and all of them were older than 30 years at the onset of seizure. Thirteen patients (76%) experienced their seizures while playing the oriental card game "Go-stop" and the remaining four patients (24%) experienced them while playing the oriental board game "Baduk". Generalized tonic-clonic seizures were frequently preceded by prodromal symptoms, but myoclonus was not evident. Most patients had no spontaneous seizures and generalized epileptiform discharges on EEGs, and infrequent seizures that were well controlled. Conclusions Our patients exhibited some features that differ from those described previously in the literature, suggesting that the clinical spectrum of reflex epilepsy induced by thinking and spatial tasks is wide. PMID:20396530

  14. Stapedial reflex and recruitment: what is the relationship with tinnitus?

    PubMed

    Fernandes, Fernando Laffitte; Guimarães, Alexandre Caixeta; de Carvalho, Guilherme Machado; Mezzalira, Raquel; Stoler, Guita; Paschoal, Jorge Rizzato

    2014-01-01

    Tinnitus is characterized by an auditory perception of sound, with no stimuli from the external environment. Tinnitus is an increasingly significant complaint, affecting 10-17% of the world population. As a symptom, it should always be considered with pathology in the auditory system. Our study aims to assess the relationship of this symptom with the presence of a stapedial reflex and the phenomenon of recruitment. Medical records of patients complaining of subjective tinnitus during their first consultation in the Outpatient Clinic of the Unicamp Teaching Hospital, in Brazil, between 2011 and 2012 were analyzed. We carried out a study with 65 non-randomized tinnitus individuals using questionnaires, clinical and audiological evaluations. The visual analogue scale was used to characterize the degree of disturbance caused by tinnitus. Statistical tests were performed using the IBM SPSS Statistics 19. No association was found between tinnitus and the presence of acoustic reflex or phenomenon of recruitment. We concluded that there is no relationship between tinnitus, the phenomenon of recruitment or the presence of an acoustic reflex. PMID:25387539

  15. Sweet Taste and Menthol Increase Cough Reflex Thresholds

    PubMed Central

    Wise, Paul M.; Breslin, Paul A.S.; Dalton, Pamela

    2015-01-01

    Cough is a vital protective reflex that is triggered by both mechanical and chemical stimuli. The current experiments explored how chemosensory stimuli modulate this important reflex. Cough thresholds were measured using a single-inhalation capsaicin challenge. Experiment 1 examined the impact of sweet taste: Cough thresholds were measured after rinsing the mouth with a sucrose solution (sweet) or with water (control). Experiment 2 examined the impact of menthol: Cough thresholds were measured after inhaling headspace above a menthol solution (menthol vapor) or headspace above the mineral oil solvent (control). Experiment 3 examined the impact of rinsing the mouth with a (bitter) sucrose octaacetate solution. Rinsing with sucrose and inhaling menthol vapor significantly increased measured cough thresholds. Rinsing with sucrose octaacete caused a non-significant decrease in cough thresholds, an important demonstration of specificity. Decreases in cough reflex sensitivity from sucrose or menthol could help explain why cough syrups without pharmacologically active ingredients are often almost as effective as formulations with an added drug. Further, the results support the idea that adding menthol to cigarettes might make tobacco smoke more tolerable for beginning smokers, at least in part, by reducing the sensitivity of an important airway defense mechanism. PMID:22465565

  16. Primitive reflexes in amyotrophic lateral sclerosis: prevalence and correlates.

    PubMed

    Tremolizzo, Lucio; Susani, Emanuela; Lunetta, Christian; Corbo, Massimo; Ferrarese, Carlo; Appollonio, Ildebrando

    2014-06-01

    Identifying frontal impairment in ALS is an important goal albeit disease-dedicated tools are still scarce. For this reason, we decided to consider primitive reflexes (PRs), variably regarded as correlates of frontal release and/or of upper motor neuron (UMN) impairment, often in the setting of dementias. Specifically, the aims of this work consisted in assessing the exact prevalence of the combination of seven PRs in ALS, trying to clarify their role as putative proxies of cognitive impairment or of UMN dysfunction. In this cross-sectional study, 50 consecutive ALS outpatients were evaluated for the presence of: palmomental (PM), corneomandibular (CM), glabella tap (MY), rooting, sucking, snout, and grasping reflexes. Cognitive screening was performed by the Frontal Assessment Battery (FAB) and the Weigl's Sorting test (WST); UMN dysfunction was concomitantly evaluated. PM, CM and MY were more frequently detected (62, 52, and 44 % of the ALS sample, respectively), while the other reflexes were under-represented. Patients displaying three or more PRs had significantly lower FAB and WST scores. On the other hand, UMN dysfunction was only moderately associated to PRs. In conclusion, PRs' assessment is a promising complementary tool for screening cognitive impairment in ALS; however, further work will be necessary to establish its added value with respect to already existing ALS-dedicated screening tools for cognition. PMID:24728376

  17. Enhanced wind-up of the C-fiber-mediated nociceptive flexor reflex movement following painful diabetic neuropathy in mice.

    PubMed

    Kimura, Satoko; Tanabe, Mitsuo; Honda, Motoko; Ono, Hideki

    2005-02-01

    We examined wind-up of the nociceptive flexor withdrawal responses in diabetic mice that had developed tactile allodynia after treatment with streptozotocin (STZ). In control and STZ-treated mice, simultaneous activation of Adelta- and C-fibers by electrical stimuli at C-fiber intensity delivered to the ventral aspect of the toe elicited a biphasic withdrawal reflex composed of short- and long-latency movements of the ipsilateral hind paw that were respectively mediated by activation of Adelta- and C-fibers. There were no significant differences between control and diabetic mice in the activation threshold of each reflex movement or the amplitude of reflexes elicited by various stimulus intensities. However, a repetitive conditioning stimulus (CS) elicited significantly greater wind-up of the C-fiber-mediated movement and early saturation of wind-up in diabetic mice. In both control and diabetic mice, the CS elicited no or occasionally slight wind-up of the A delta-fiber-mediated movement. Moreover, post-CS facilitation, which reflects the prolonged excitability increase, was observed in both Adelta-fiber- and C-fiber-mediated movements of control mice, whereas significant post-CS facilitation was only obtained in the C-fiber-mediated movement of diabetic mice, which may reflect supraspinal descending influences. Such changes in the excitability of spinal neurons in diabetic mice may represent some aspect of painful diabetic neuropathy. PMID:15684569

  18. The Correlation between Modified Ashworth Scale and Biceps T-reflex and Inter-rater and Intra-rater Reliability of Biceps T-reflex

    PubMed Central

    Min, Ji Hong; Joa, Kyung Lim; Ko, Sung Hwa; Shin, Myung Jun; Chang, Jae Hyeok; Ko, Hyun-Yoon

    2012-01-01

    Objective To establish a correlation between the modified Ashworth scale (MAS) and amplitude and latency of T-reflex and to demonstrate inter-rater and intra-rater reliability of the T-reflex of the biceps muscle for assessing spasticity after stroke. Method A total of 21 patients with hemiplegia and spasticity after ischemic stroke were enrolled for this study. The spasticity of biceps muscle was evaluated by an occupational therapist using the MAS. The mean value of manual muscle test of biceps muscles was 2.3±0.79. Latency and amplitude of T-reflex were recorded from biceps muscles by two physicians. The onset latency and peak to peak amplitude of the mean of 5 big T-reflex were measured. The examinations were carried out by two physicians at the same time to evaluate the inter-rater reliability. Further, one of the physicians performed the examination again after one week to evaluate the intra-rater reliability. The correlations between MAS and T-reflex, and the intra- and inter-rater reliability of biceps T-reflex were established by calculating the Spearman correlation coefficients and the intra-class correlation coefficients (ICCs). Results Amplitude of the biceps T-reflex increased with increasing level of MAS (rs=0.464 and 0.573, respectively, p<0.01). ICCs of latency and amplitude of biceps T-reflex were 0.914 and 0.822. The Spearman correlation coefficients of latency and amplitude of biceps T-reflex were 0.937 and 0.635, respectively (p<0.01). Conclusion Biceps T-reflex demonstrates a good quantitative measurement and correlation tool with MAS for spasticity, and also shows acceptable inter- and intra-rater reliability, which can be used for patients with spasticity after stroke. PMID:22977780

  19. Vestibulo-spinal and vestibulo-ocular reflexes are modulated when standing with increased postural threat.

    PubMed

    Naranjo, E N; Cleworth, T W; Allum, J H J; Inglis, J T; Lea, J; Westerberg, B D; Carpenter, M G

    2016-02-01

    We investigated how vestibulo-spinal reflexes (VSRs) and vestibulo-ocular reflexes (VORs) measured through vestibular evoked myogenic potentials (VEMPs) and video head impulse test (vHIT) outcomes, respectively, are modulated during standing under conditions of increased postural threat. Twenty-five healthy young adults stood quietly at low (0.8 m from the ground) and high (3.2 m) surface height conditions in two experiments. For the first experiment (n = 25) VEMPs were recorded with surface EMG from inferior oblique (IO), sternocleidomastoid (SCM), trapezius (TRP), and soleus (SOL) muscles in response to 256 air-conducted short tone bursts (125 dB SPL, 500 Hz, 4 ms) delivered via headphones. A subset of subjects (n = 19) also received horizontal and vertical head thrusts (∼150°/s) at each height in a separate session, comparing eye and head velocities by using a vHIT system for calculating the functional VOR gains. VEMP amplitudes (IO, TRP, SOL) and horizontal and vertical vHIT gains all increased with high surface height conditions (P < 0.05). Changes in IO and SCM VEMP amplitudes as well as horizontal vHIT gains were correlated with changes in electrodermal activity (ρ = 0.44-0.59, P < 0.05). VEMP amplitude for the IO also positively correlated with fear (ρ = 0.43, P = 0.03). Threat-induced anxiety, fear, and arousal have significant effects on VSR and VOR gains that can be observed in both physiological and functional outcome measures. These findings provide support for a potential central modulation of the vestibular nucleus complex through excitatory inputs from neural centers involved in processing fear, anxiety, arousal, and vigilance. PMID:26631147

  20. 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

  1. Plantar grasp reflex in high-risk infants during the first year of life.

    PubMed

    Zafeiriou, D I

    2000-01-01

    For most primitive reflexes, retention of the reflex beyond the period when it should no longer be elicited suggests a pathologic process within the central nervous system. However, for certain primitive reflexes, such as the plantar grasp reflex, a negative response within the first months of life is suggestive of a neurologic abnormality. From the results of one prospective and one retrospective study, it is clearly indicated that the absence of the plantar grasp reflex from 3 months of age and on correlates with the development of spastic cerebral palsy. The specific combination of presence or absence of specific primitive reflexes, postural reactions, or both may accurately predict a specific type of cerebral palsy or neurodevelopmental abnormality. PMID:10669212

  2. Postnatal development of the nociceptive withdrawal reflexes in the rat: a behavioural and electromyographic study.

    PubMed Central

    Holmberg, H; Schouenborg, J

    1996-01-01

    1. The postnatal development of nociceptive withdrawal reflexes was studied. In awake intact rats, forelimb, hindlimb and tail reflexes were recorded on videotape. In decerebrate spinal rats, electromyography (EMG) was used to record nociceptive withdrawal reflexes in musculi extensor digitorum longus (EDL), peronei, gastrocnemius-soleus (G-S) and biceps posterior-semitendinosus (BP-ST). Thermal (short-lasting CO2 laser pulses) and mechanical stimulation were used. 2. In adults, nociceptive withdrawal reflexes were typically well directed and reflex pathways to single hindlimb muscles had functionally adapted receptive fields. By contrast, at postnatal day (P) 1-7, the nociceptive withdrawal reflexes were often inappropriate, sometimes producing movements towards the stimulation, and EMG recordings revealed unadapted variable receptive fields. With increasing age, the nociceptive withdrawal reflexes progressively became well directed, thus producing localized withdrawal. Both withdrawal movements and spatial organization of the receptive fields were adult-like at P20-25. 3. Up to P25, reflex thresholds were more or less constant in both intact awake rats and spinal decerebrate rats, except in G-S in which no nociceptive withdrawal reflexes were evoked from P20 on. After P25, mechanical, but not thermal, thresholds increased dramatically. 4. EMG recordings revealed that during the first three postnatal weeks, the latency of the CO2 laser-evoked nociceptive withdrawal reflexes decreased significantly in peronei and BP-ST, but not in EDL, and thereafter increased significantly in peronei, BP-ST and EDL. The magnitude of the nociceptive withdrawal reflexes in these muscles increased markedly between P7 and P20 and showed little change thereafter. 5. Possible mechanisms underlying the postnatal tuning of the nociceptive withdrawal reflexes are discussed. PMID:8735709

  3. 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

  4. Co-contraction modifies the stretch reflex elicited in muscles shortened by a joint perturbation

    PubMed Central

    Lewis, Gwyn N.; MacKinnon, Colum D.; Trumbower, Randy; Perreault, Eric J.

    2011-01-01

    Simultaneous contraction of agonist and antagonist muscles acting about a joint influences joint stiffness and stability. Although several studies have shown that reflexes in the muscle lengthened by a joint perturbation are modulated during co-contraction, little attention has been given to reflex regulation in the antagonist (shortened) muscle. The goal of the present study was to determine whether co-contraction gives rise to altered reflex regulation across the joint by examining reflexes in the muscle shortened by a joint perturbation. Reflexes were recorded from electromyographic activity in elbow flexors and extensors while positional perturbations to the elbow joint were applied. Perturbations were delivered during isolated activation of the flexor or extensor muscles as well as during flexor and extensor co-contraction. Across the group, the shortening reflex in the elbow extensor switched from suppression during isolated extensor muscle activation to facilitation during co-contraction. The shortening reflex in the elbow flexor remained suppressive during co-contraction but was significantly smaller compared to the response obtained during isolated elbow flexor activation. This response in the shortened muscle was graded by the level of activation in the lengthened muscle. The lengthening reflex did not change during co-contraction. These results support the idea that reflexes are regulated across multiple muscles around a joint. We speculate that the facilitatory response in the shortened muscle arises through a fast-conducting oligosynaptic pathway involving Ib interneurons. PMID:20878148

  5. A stereotypic "elbowing" movement, a possible new primitive reflex in newborns.

    PubMed

    Saraga, Marijan; Resi?, Biserka; Krni?, Dragan; Jelavi?, Tihana; Krni?, Duska; Sinovci?, Ivana; Tomasovi?, Maja

    2007-02-01

    The primitive reflexes are brainstem-mediated and play various roles in the child's psychomotor development. The objective of the current study is to describe a new pattern of primitive reflex, noticed in 52 of 81 randomly chosen newborns and young infants during pressing of the subcostal region. Some of them reacted by three-phase stereotypic movement as follows: phase 1: quick adduction of upper arm with flexion of the forearm, with elbow directed toward the site of stimuli, touching the stimulated area; phase 2: abduction and retroflexion of upper arm with the movement of removing the stimulus with the elbow; phase 3: extension and pronation of the forearm. The prevalence of this newly described reflex was 64.2%. The incidence of all three phases together was highest at Day 16 (63.5%); phase 1 was the most frequent at Day 30 (88.5%) in 52 children with positive reflex. At Day 86, only 18.4% of them retained the first phase of the movement and 2% retained the third phase. All reflexes appeared until Day 30. We believe that we have described a new primitive reflex, with all characteristics essential for primitive reflexes. It is definitely involuntary, complex, stereotypic, with decreased incidence over time. Because of the defensive purpose and peculiar manner of this reflex, we named it the "elbowing reflex." PMID:17275658

  6. Learning reflexively from a health promotion professional development program in Canada.

    PubMed

    Tremblay, Marie-Claude; Richard, Lucie; Brousselle, Astrid; Beaudet, Nicole

    2014-09-01

    In recent decades, reflexivity has received much attention in the professional education and training literature, especially in the public health and health promotion fields. Despite general agreement on the importance of reflexivity, there appears to be no consensus on how to assess reflexivity or to conceptualize the different forms developed among professionals and participants of training programs. This paper presents an analysis of the reflexivity outcomes of the Health Promotion Laboratory, an innovative professional development program aimed at supporting practice changes among health professionals by fostering competency development and reflexivity. More specifically, this paper explores the difference between two levels of reflexivity (formative and critical) and highlights some implications of each for practice. Data were collected through qualitative interviews with participants from two intervention sites. Results showed that involvement in the Health Promotion Laboratory prompted many participants to modify their vision of their practice and professional role, indicating an impact on reflexivity. In many cases, new understandings seem to have played a formative function in enabling participants to improve their practice and their role as health promoters. The reflective process also served a critical function culminating in a social and moral understanding of the impacts on society of the professionals' practices and roles. This type of outcome is greatly desired in health promotion, given the social justice and equity concerns of this field of practice. By redefining the theoretical concept of reflexivity on two levels and discussing their impacts on practice, this study supports the usefulness of both levels of reflexivity. PMID:23996539

  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. Reflexivity: The Creation of Liminal Spaces-Researchers, Participants, and Research Encounters.

    PubMed

    Enosh, Guy; Ben-Ari, Adital

    2016-03-01

    Reflexivity is defined as the constant movement between being in the phenomenon and stepping outside of it. In this article, we specify three foci of reflexivity-the researcher, the participant, and the encounter-for exploring the interview process as a dialogic liminal space of mutual reflection between researcher and participant. Whereas researchers' reflexivity has been discussed extensively in the professional discourse, participants' reflexivity has not received adequate scholarly attention, nor has the promise inherent in reflective processes occurring within the encounter. PMID:25987582

  9. 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.

  10. Learning reflexively from a health promotion professional development program in Canada

    PubMed Central

    Tremblay, Marie-Claude; Richard, Lucie; Brousselle, Astrid; Beaudet, Nicole

    2014-01-01

    In recent decades, reflexivity has received much attention in the professional education and training literature, especially in the public health and health promotion fields. Despite general agreement on the importance of reflexivity, there appears to be no consensus on how to assess reflexivity or to conceptualize the different forms developed among professionals and participants of training programs. This paper presents an analysis of the reflexivity outcomes of the Health Promotion Laboratory, an innovative professional development program aimed at supporting practice changes among health professionals by fostering competency development and reflexivity. More specifically, this paper explores the difference between two levels of reflexivity (formative and critical) and highlights some implications of each for practice. Data were collected through qualitative interviews with participants from two intervention sites. Results showed that involvement in the Health Promotion Laboratory prompted many participants to modify their vision of their practice and professional role, indicating an impact on reflexivity. In many cases, new understandings seem to have played a formative function in enabling participants to improve their practice and their role as health promoters. The reflective process also served a critical function culminating in a social and moral understanding of the impacts on society of the professionals' practices and roles. This type of outcome is greatly desired in health promotion, given the social justice and equity concerns of this field of practice. By redefining the theoretical concept of reflexivity on two levels and discussing their impacts on practice, this study supports the usefulness of both levels of reflexivity. PMID:23996539

  11. The Validity and Reliability of Motion Analysis in Patellar Tendon Reflex Assessment

    PubMed Central

    Tham, Lai Kuan; Abu Osman, Noor Azuan; Wan Abas, Wan Abu Bakar; Lim, Kheng Seang

    2013-01-01

    Background The deep tendon reflex assessments that are essential to the accurate diagnosis of neurological or neuromuscular disorders are conducted subjectively in clinical neurology. Our aim was to assess deep tendon reflexes objectively with a new reflex quantification method. Methodology/Principal Findings The present study used a motion analysis technique to collect quantitative measurements for both the input and output of normal patellar tendon reflex. Reflex responses were measured as knee angles. The patellar tendon reflexes of 100 healthy subjects were examined using 6 levels of tendon taps, where all the assessments were captured using motion capture system. A linear relationship was found between the experimental maximum tapping velocity and tapping angle (coefficient of determination = 0.989), which was consistent with the theoretical values. Tapping velocities were predictable according to tapping angles. The findings proved the reproducibility of tapping method in producing consistent input. The reflex amplitude was consistent between two randomly assigned groups, and linearly proportionate to the tapping velocity. Conclusions/Significance The findings on reflex amplitude indicate that motion analysis is a valid and reliable method of assessing and measuring deep tendon reflexes. PMID:23409022

  12. Methodological optimization of tinnitus assessment using prepulse inhibition of the acoustic startle reflex.

    PubMed

    Longenecker, R J; Galazyuk, A V

    2012-11-16

    Recently prepulse inhibition of the acoustic startle reflex (ASR) became a popular technique for tinnitus assessment in laboratory animals. This method confers a significant advantage over the previously used time-consuming behavioral approaches utilizing basic mechanisms of conditioning. Although this technique has been successfully used to assess tinnitus in different laboratory animals, many of the finer details of this methodology have not been described enough to be replicated, but are critical for tinnitus assessment. Here we provide detail description of key procedures and methodological issues that provide guidance for newcomers with the process of learning to correctly apply gap detection techniques for tinnitus assessment in laboratory animals. The major categories of these issues include: refinement of hardware for best performance, optimization of stimulus parameters, behavioral considerations, and identification of optimal strategies for data analysis. This article is part of a Special Issue entitled: Tinnitus Neuroscience. PMID:22513102

  13. Feasibility analysis of digital single lens reflex applied in the field of aerospace measurement

    NASA Astrophysics Data System (ADS)

    Feng, Xinghao; Li, Manliang; Tang, Xuehai

    2015-10-01

    The mainstrean digital single lens reflex (DSLR) image has the characteristics of true color and high quality, this paper proposes apply DSLR to probe spacecraft in order to obtain better quality Color images. Firstly, the performance parameters of mainstream DSLR and industrial-grade optical detector are analysed and compared detailedly; Secondly, the performance and positioning ways etc. of optical detector and DSLR system integrated special telephoto lens are analysed and compared. Furthermore, some experiments have been done in different conditions. The experiments indicate that the performances of DSLR and optical detector are similar. In addition, DSLR has the advantage of small size, low cost and Easy positioning, which can be used to obtain the scene of spacecraft in the takeoff phase and part of reentry phase.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  15. Fatigue-related depression of the feline monosynaptic gastrocnemius–soleus reflex

    PubMed Central

    Kalezic, Ivana; Bugaychenko, Larisa A; Kostyukov, Alexander I; Pilyavskii, Alexander I; Ljubisavljevic, Milos; Windhorst, Uwe; Johansson, Håkan

    2004-01-01

    In decerebrate cats, changes in the monosynaptic reflex (MSR) of gastrocnemius–soleus (G–S) motoneurones were studied after fatiguing stimulation (FST) of the G–S muscles. Monosynaptic reflexes were evoked by stimulation of Ia fibres in the G–S nerve and recorded from a filament of ventral root (VR) L7. FST (intermittent 40 s?1 stimulation for 10–12 min) was applied to the distal part of the cut VR S1. FST reduced MSR amplitudes to 0.64 ± 0.04 (mean ±s.e.m.) of the prefatigue values. The suppression remained stable for approximately 25 min and then MSR amplitudes gradually returned towards the normal. To test for the involvement of presynaptic and recurrent inhibition, MSRs were conditioned by stimulation of the nerve to the posterior biceps and semitendinosus (PBSt) muscles or a filament of VR L7, respectively. The intensity of presynaptic inhibition (reduction of the normalized value of MSR amplitude during conditioning) increased from 0.19 ± 0.02 in prefatigue to 0.44 ± 0.04 within a 5.3–18.2 min interval after FST, followed by a recovery. In contrast, the intensity of recurrent inhibition first diminished from 0.23 ± 0.02 in prefatigue to 0.15 ± 0.01 within 15.6–30.1 min after FST and then gradually recovered. Both primary afferent depolarization and the intensity of antidromic discharges in primary afferents increased with the presynaptic inhibition intensity. These results demonstrate a fatigue-related suppression of Ia excitation of synergistic motoneurones, probably arising from the activation of group III and IV afferents. The effects could in part be due to increased presynaptic inhibition, while recurrent inhibition plays a minor role. PMID:14645451

  16. Exploring the practice of patient centered care: The role of ethnography and reflexivity.

    PubMed

    Liberati, Elisa Giulia; Gorli, Mara; Moja, Lorenzo; Galuppo, Laura; Ripamonti, Silvio; Scaratti, Giuseppe

    2015-05-01

    Patient centered care (PCC) is an essential dimension of healthcare systems' mission worldwide and is recognized as an important condition for ensuring the quality of care. Nonetheless, it is also acknowledged that various care providers perceive patient centeredness differently and that there remain several unanswered questions about the aspects of healthcare delivery that are linked to an actual achievement of PCC. In the paper, we categorize the current research on PCC into two streams ("dyadic" and "organizational") and we discuss the strengths and weaknesses of each. Despite their important contributions to healthcare services research, these approaches to PCC do not fully capture the network of practices and relationships constituting patients and providers' experiences within healthcare contexts. Therefore, we propose an alternative interpretation of PCC that integrates insights from "practice theories" and emphasizes the negotiated and local nature of patient centeredness, which is accomplished through the engagement of providers and patients in everyday care practices. To develop such interpretation, we propose a research approach combining ethnographic and reflexive methods. Ethnography can help achieve more nuanced descriptions of what PCC truly encapsulates in the care process by drawing attention to the social and material reality of healthcare contexts. Reflexivity can help disentangle and bring to surface the tacit knowledge spread in everyday care practices and transform it into actionable knowledge, a type of knowledge that may support services improvement toward PCC. We anticipate that such improvement is far from straightforward: an actual achievement of PCC may challenge the interests of different stakeholders and unsettle consolidated habits, hierarchies and power dynamics. This unsettlement, however, can also serve as a necessary condition for engaging in a participative process of internal development. We discuss the outcomes, limitations and benefits of our approach through a hospital case study. PMID:25841094

  17. Maturation of respiratory reflex responses in the piglet.

    PubMed

    Haxhiu-Poskurica, B; Carlo, W A; Miller, M J; DiFiore, J M; Haxhiu, M A; Martin, R J

    1991-02-01

    Stimulation of chemo-, irritant, and pulmonary C-fiber receptors reflexly constricts airway smooth muscle and alters ventilation in mature animals. These reflex responses of airway smooth muscle have, however, not been clearly characterized during early development. In this study we compared the maturation of reflex pathways regulating airway smooth muscle tone and ventilation in anesthetized, paralyzed, and artificially ventilated 2- to 3- and 10-wk-old piglets. Tracheal smooth muscle tension was measured from an open tracheal segment by use of a force transducer, and phrenic nerve activity was measured from a proximal cut end of the phrenic nerve. Inhalation of 7% CO2 caused a transient increase in tracheal tension in both age groups, whereas hypoxia caused no airway smooth muscle response in either group. The phrenic responses to 7% CO2 and 12% O2 were comparable in both age groups. Lung deflation and capsaicin (20 micrograms/kg iv) administration did not alter tracheal tension in the younger piglets but caused tracheal tension to increase by 87 +/- 28 and 31 +/- 10%, respectively, in the older animals (both P less than 0.05). In contrast, phrenic response to both stimuli was comparable between ages: deflation increased phrenic activity while capsaicin induced neural apnea. Laryngeal stimulation did not increase tracheal tension but induced neural apnea in both age groups. These data demonstrate that between 2 and 10 wk of life, piglets exhibit developmental changes in the reflex responses of airway smooth muscle situated in the larger airways in response to irritant and C-fiber but not chemoreceptor stimulation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2022552

  18. 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.

  19. 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.

  20. 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.

  1. Hot water epilepsy: A rare form of reflex epilepsy

    PubMed Central

    Syed, Riazahmed

    2010-01-01

    Hot water epilepsy is a form of reflex epilepsy in childhood. We report two children from Saudi Arabia, who presented with seizures following pouring hot water on their head, while bathing. They were not treated by anti-epileptic medication. By decreasing the temperature of the water used for bathing, the seizures were avoided to a large extent in them. This form of epilepsy is reported to be seldom present in various countries but there are no records of its presence in Saudi Arabia. PMID:21808513

  2. Anode-plasma expansion in pinch-reflex diodes

    SciTech Connect

    Colombant, D.G.; Goldstein, S.A.

    1983-10-24

    Anode-plasma expansion in pinch-reflex diodes is investigated with use of a one-dimensional magnetohydrodynamic model. Early in time, the plasma undergoes thermal expansion and its front is slowed down as a result of j x B. After the current has reached its maximum and for small radius where j and B are larger, j x B may accelerate the bulk of the anode plasma to large velocities. Good qualitative agreement is obtained with observations of the time dependence of the plasma velocity as well as its radial profile. The maximum expansion velocities reach tens of centimeters per microsecond.

  3. Formation of H/sup -/ beams in reflex systems

    SciTech Connect

    Bystritskii, V.M.; Volkov, S.N.; Krasik, Y.E.

    1986-11-01

    The formation of H/sup -/ beams in reflex systems has been studied. The use of charge-exchange method and suppression of the background from protons accelerated from the anode made it possible to determine the concentration of H/sup -/ ions in the plasma near the cathode at the level of 0.5--2%. The H/sup -/ current density lies in the range 0.25 +- 0.15 A/cm/sup 2/. A significant improvement in measurement accuracy can be achieved by using a deuterated coating on the cathode and by switching to a high accelerator current density.

  4. 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. ); Ebersole, K.L.; Judy, D.C.; Lezcano, P.A.; Pereira, N.R.; Weidenheimer, D.M. )

    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.

  5. Abnormal pupillary light reflex with chromatic pupillometry in Gaucher disease

    PubMed Central

    Narita, Aya; Shirai, Kentarou; Kubota, Norika; Takayama, Rumiko; Takahashi, Yukitoshi; Onuki, Takanori; Numakura, Chikahiko; Kato, Mitsuhiro; Hamada, Yusuke; Sakai, Norio; Ohno, Atsuko; Asami, Maya; Matsushita, Shoko; Hayashi, Anri; Kumada, Tomohiro; Fujii, Tatsuya; Horino, Asako; Inoue, Takeshi; Kuki, Ichiro; Asakawa, Ken; Ishikawa, Hitoshi; Ohno, Koyo; Nishimura, Yoko; Tamasaki, Akiko; Maegaki, Yoshihiro; Ohno, Kousaku

    2014-01-01

    The hallmark of neuronopathic Gaucher disease (GD) is oculomotor abnormalities, but ophthalmological assessment is difficult in uncooperative patients. Chromatic pupillometry is a quantitative method to assess the pupillary light reflex (PLR) with minimal patient cooperation. Thus, we investigated whether chromatic pupillometry could be useful for neurological evaluations in GD. In our neuronopathic GD patients, red light-induced PLR was markedly impaired, whereas blue light-induced PLR was relatively spared. In addition, patients with non-neuronopathic GD showed no abnormalities. These novel findings show that chromatic pupillometry is a convenient method to detect neurological signs and monitor the course of disease in neuronopathic GD. PMID:25356393

  6. 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.

  7. 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

  8. Production of intense ion beams in a reflex triode with an external plasma source at the anode

    SciTech Connect

    Bystritskii, V.M.; Verigin, A.A.; Volkov, S.N.; Krasik, Y.E.; Podkatov, V.I.

    1986-09-01

    An experimental study of the production of intense ion beams in a reflex triode with an external plasma source at the anode is reported. The ions had various ratios Z/M. When the anode plasma is produced in a preliminary charging pulse of the accelerator, the plasma density is too low for operation under charge-limited emission conditions. In this case, an ion beam is observed to be produced from the plasma formed by the direct heating of the anode material by oscillating electrons. When an anode plasma resulting from the breakdown of a dielectric insert or of the vacuum gap of a composite andode by an external voltage source is used to produce an ion beam, the reflex triode operating conditions depend on delaying the operation of the accelerator with respect to the external source. The highest efficiency (approx. =20%) in the production of an ion beam is observed at t/sub d/ = 3--6 ..mu..s. In this case, the reflex triode operates under increasing or constant impedance conditions. It was shown in the course of the experiments that the ion beam which is produced is nonuniform. There are three groups of ions: H/sup +/, C/sup n//sup +/, and Cu/sup n//sup +/. The energy of the heavy ions depends on the applied anode potential. The different mass components of the ion beam do not appear at the same time. The macroscopic divergence of the beam is 4--6/sup 0/ at the periphery and drops off to approx. <1/sup 0/ at the center. The microscopic divergence of the beam is 3/sup 0/. The total energy of the ion beam which is produced is less than 120 J at an average current approx. =2.8 kA.

  9. [Characteristics of the conditioned motor reactions of unrestrained elasmobranches and teleosts].

    PubMed

    Maliukova, I V; Rakic, L; Kovacevic, N

    1979-01-01

    In elasmobranch (Scyllium canicula, Galleus canis) and teleost (Migull capitocum) fishes it is possible to form motor food-searching conditioned reflexes to discrimination of light and darkness. Some differences were revealed in ecological and conditioned motor behavioural activities in higher and lower sharks. Elasmobranch and teleost fishes exhibit significant differences in ecological, feeding and conditioned reflex behaviour. Nervous activity in elasmobranchs is characterized by lower and primitive organization as compared to that in teleosts. PMID:516946

  10. 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.

  11. 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.

  12. Tuning of human vestibulospinal reflexes by leg rotation.

    PubMed

    Grasso, C; Barresi, M; Scattina, E; Orsini, P; Vignali, E; Bruschini, L; Manzoni, D

    2011-04-01

    Changing the foot position modifies the mechanical action exerted by the ankle extensor and flexor muscles over the body. We verified, in two groups of healthy subjects standing with the heels touching or apart, whether a 90° external rotation of the right leg and foot also changes the pattern of vestibulospinal reflexes elicited by electrical stimulation of the labyrinth. With the head oriented forward, leg rotation did not modify the labyrinthine-driven displacements of the center of pressure (CoP). When the head was rotated in the horizontal plane, either to the right or to the left, the CoP displacement increased along the y axis in all subjects. Changes in the x component in most instances appropriate to preserve unmodified the direction of body sway elicited by the stimulus were observed. Right leg rotation increased the basal EMG activity of ankle extensors and flexors on the left side, while the right side activity was unaffected. The EMG responses to labyrinthine stimulation were modified only on the left side, in a way appropriate to correct the effects of the altered torque pattern exerted on the body by right leg muscles. It appears, therefore, that somatosensory signals related to leg rotation and/or copy of the corresponding voluntary motor commands modify the pattern of vestibulospinal reflexes and maintain the postural response appropriate to counteract a body sway in the direction inferred by labyrinthine signals. PMID:20813417

  13. 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.

  14. Forebrain neurocircuitry associated with human reflex cardiovascular control

    PubMed Central

    Shoemaker, J. Kevin; Goswami, Ruma

    2015-01-01

    Physiological homeostasis depends upon adequate integration and responsiveness of sensory information with the autonomic nervous system to affect rapid and effective adjustments in end organ control. Dysregulation of the autonomic nervous system leads to cardiovascular disability with consequences as severe as sudden death. The neural pathways involved in reflexive autonomic control are dependent upon brainstem nuclei but these receive modulatory inputs from higher centers in the midbrain and cortex. Neuroimaging technologies have allowed closer study of the cortical circuitry related to autonomic cardiovascular adjustments to many stressors in awake humans and have exposed many forebrain sites that associate strongly with cardiovascular arousal during stress including the medial prefrontal cortex, insula cortex, anterior cingulate, amygdala and hippocampus. Using a comparative approach, this review will consider the cortical autonomic circuitry in rodents and primates with a major emphasis on more recent neuroimaging studies in awake humans. A challenge with neuroimaging studies is their interpretation in view of multiple sensory, perceptual, emotive and/or reflexive components of autonomic responses. This review will focus on those responses related to non-volitional baroreflex control of blood pressure and also on the coordinated responses to non-fatiguing, non-painful volitional exercise with particular emphasis on the medial prefrontal cortex and the insula cortex. PMID:26388780

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

    PubMed

    Walklate, Sandra; Mythen, Gabriel

    2010-03-01

    The purpose of this paper is to critically examine the turn to risk within sociology and to survey the relationship between structure and agency as conceived by popular strands of risk theorizing. To this end, we appraise the risk society, culture of fear and governmentality perspectives and we consider the different imaginings of the citizen constructed by each of these approaches. The paper goes on to explore what each of these visions of citizenship implies for understandings of the structure/agency dynamic as it pertains to the question of reflexivity. In order to transcend uni-dimensional notions of citizenship and to reinvigorate sociological debates about risk, we call for conceptual analyses that are contextually rooted. Exampling the importance of knowledge contests around contemporary security threats and warnings of the deleterious effects of pre-emptive modes of regulation that derive from the 'risk turn' within social science, we argue for a more nuanced embrace of reflexivity within risk theorising in order to facilitate a more dynamic critique of the images of citizenship that such theorizing promotes. PMID:20377596

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

    PubMed

    Harcourt, Wendy

    2016-01-01

    Using the example of a human rights training in Nepal, the author looks at global body politics in a reflexive piece on her engagement in development practices that translate western feminist ideas on gender inequality and empowerment via UN human rights policies into non-western contexts. It firsts look at postcolonial and critical literature on feminist engagement in gender and development processes including a discussion on the concept of global body politics before examining briefly the framing of gender-based violence in Nepal. The core of the paper is a reflexive analysis and interrogation of the training in Nepal in order to bring out the tensions and contradictions around western developmental, feminist and human rights discourses. The discussion looks at how difficult it is for feminist, human rights and developmental discourses and practices to unmoor themselves from the notion of the 'expert' and those who do the rights/work/righting rights training and those who are perennially seen as requiring training. The conclusion reflects on possibilities of other epistemic practices found in intercultural dialogues. PMID:26268778

  17. Participation of the anterior hypothalamus in the baroreceptor reflex

    PubMed Central

    Hilton, S. M.; Spyer, K. M.

    1971-01-01

    1. On the basis of discrete electrical stimulation in the pre-optic region and anterior hypothalamus of anaesthetized cats, a depressor area has been defined, stimulation of which elicits a fall of arterial blood pressure of 30-50 mm Hg and a bradycardia of some 25%, caused by inhibition of sympathetic vasomotor tone and by vagal activation respectively. These are accompanied by a reduction in rate and depth of respiration. 2. The depressor area, from which this pattern of response is elicited, lies ventral and caudal to the anterior commissure, and extends caudally in the dorsal hypothalamus, dorsal to the fornix. 3. The pattern of response elicited from identified points in the depressor area was shown to be indistinguishable from that to baroreceptor afferent stimulation. 4. A lesion destroying the hypothalamic depressor area bilaterally reduced the response to baroreceptor afferent stimulation. Lesions in the medullary depressor area which spared a large part of the nucleus of the tractus solitarius also reduced, but did not abolish, the baroreceptor reflex response. The two lesions combined abolished the reflex. 5. It is concluded that the whole brain-stem depressor area, from the hypothalamus through the mid-brain to the medulla, constitutes a functional unit which integrates the response to baroreceptor afferent stimulation. PMID:5124567

  18. 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

  19. Virtues in participatory design: cooperation, curiosity, creativity, empowerment and reflexivity.

    PubMed

    Steen, Marc

    2013-09-01

    In this essay several virtues are discussed that are needed in people who work in participatory design (PD). The term PD is used here to refer specifically to an approach in designing information systems with its roots in Scandinavia in the 1970s and 1980s. Through the lens of virtue ethics and based on key texts in PD, the virtues of cooperation, curiosity, creativity, empowerment and reflexivity are discussed. Cooperation helps people in PD projects to engage in cooperative curiosity and cooperative creativity. Curiosity helps them to empathize with others and their experiences, and to engage in joint learning. Creativity helps them to envision, try out and materialize ideas, and to jointly create new products and services. Empowerment helps them to share power and to enable other people to flourish. Moreover, reflexivity helps them to perceive and to modify their own thoughts, feelings and actions. In the spirit of virtue ethics-which focuses on specific people in concrete situations-several examples from one PD project are provided. Virtue ethics is likely to appeal to people in PD projects because it is practice-oriented, provides room for exploration and experimentation, and promotes professional and personal development. In closing, some ideas for practical application, for education and for further research are discussed. PMID:22806218

  20. Deficits in reflexive covert attention following cerebellar injury

    PubMed Central

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

    2015-01-01

    Traditionally the cerebellum has been known for its important role in coordinating motor output. Over the past 15 years numerous studies have indicated that the cerebellum plays a role in a variety of cognitive functions including working memory, language, perceptual functions, and emotion. In addition, recent work suggests that regions of the cerebellum involved in eye movements also play a role in controlling covert visual attention. Here we investigated whether regions of the cerebellum that are not strictly tied to the control of eye movements might also contribute to covert attention. To address this question we examined the effects of circumscribed cerebellar lesions on reflexive covert attention in a group of patients (n = 11) without any gross motor or oculomotor deficits, and compared their performance to a group of age-matched controls (n = 11). Results indicated that the traditional RT advantage for validly cued targets was significantly smaller at the shortest (50 ms) SOA for cerebellar patients compared to controls. Critically, a lesion overlap analysis indicated that this deficit in the rapid deployment of attention was linked to damage in Crus I and Crus II of the lateral cerebellum. Importantly, both cerebellar regions have connections to non-motor regions of the prefrontal and posterior parietal cortices—regions important for controlling visuospatial attention. Together, these data provide converging evidence that both lateral and midline regions of the cerebellum play an important role in the control of reflexive covert visual attention. PMID:26300756

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

    PubMed

    Williams, Claire; Wood, Rodger L

    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 this can vary according to the affective valence of stimuli by comparing a TBI group with a matched control group. The study also examined whether weaknesses of attention and speed of information processing could account for differences in startle modulation across groups. Sixty-four TBI patients and controls completed the startle reflex procedure. Participants were presented with pictures that differed in affective valence, and measures were taken of eyeblink startle responses to an acoustic probe. Subjective ratings of affect and arousal for each picture were obtained, and TBI patients completed measures of attention and information processing. Results revealed that the TBI group did not show the pattern of startle modulation observed in the control group. Whilst pleasant pictures produced the usual attenuation of the startle response, startle responses to unpleasant pictures were significantly lower in the TBI group than in controls. No significant correlations emerged between startle responses and performance on neuropsychological measures in the TBI group. The TBI group also rated unpleasant pictures as significantly less arousing than did controls. The results provide partial support for a growing body of evidence that has proposed impaired emotion responsivity following TBI. PMID:22873359

  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. The use of rat spinal reflexes to quantify injection pain.

    PubMed

    Ami, Nozomi; Satou, Hideki

    2015-07-10

    Pain caused by subcutaneous injections is unpleasant, which may limit patient compliance. The objective of this study was to use spinal reflexes to quantify subcutaneous injection pain. Spinal reflexes were measured using an electromyogram (EMG) test. The effects of injection volume, pH and osmotic pressure were investigated. The EMG responses increased with injection volume and the acidity of the solution but did not depend on the osmotic pressure of the solution. The EMG responses differed for subcutaneously injected sodium chloride and glucose over the same range of osmotic pressures. Pain caused by the subcutaneous injections was unrelated to the osmotic ratio up to approximately 5. The injection pain caused by therapeutic protein solutions was also evaluated. We compared the EMG responses of the adalimumab and etanercept, as the injection of adalimumab is more painful than that of etanercept in humans. The EMG magnitude for adalimumab was twice that induced by etanercept as observed for the EMG tests performed in rats. Therapeutic proteins account for an increasingly large proportion of pharmaceutical drugs. When a high dose of therapeutic proteins is required, the protein solution must often be highly concentrated to reduce the injection volume. For patient comfort, it is critical to reduce injection pain. The EMG test reported here allows subcutaneous injection pain to be quantified and may be useful for optimizing drug formulations. PMID:25850075

  4. Primitive reflex evaluation in the clinical assessment of extrapyramidal syndromes.

    PubMed

    Borroni, B; Broli, M; Costanzi, C; Gipponi, S; Gilberti, N; Agosti, C; Padovani, A

    2006-09-01

    The aim of the present study was to evaluate the role of primitive reflexes (PRs) as additional alert sign in routine clinical practice in patients with extrapyramidal syndrome. We considered glabellar, snout, palmomental and grasp reflexes in patients with mild stage of Lewy body dementia (LBD), corticobasal degeneration, progressive supranuclear palsy or Parkinson disease (PD). We also enrolled mild Alzheimer disease (AD) patients, and healthy subjects, as controls. LBD patients showed the highest prevalence of PRs compared with the other groups. The odds ratio of the risk of LBD in PRs > or = 2 was 27.9 (95% CI 2.9-269.0) compared with control group, 14.6 (95% CI 2.7-79.6) compared with mild AD, and 19.7 (95% CI 3.7-104.3) compared with PD. These data suggest that the occurrence of combination of PRs might be an useful additional warning sign of possible diffuse Lewy body pathology more than other causes of extrapyramidal syndrome. PMID:16930372

  5. Reflexive Clitics in the Slavic and Romance Languages. A Comparative View from an Antipassive Perspective

    ERIC Educational Resources Information Center

    Medova, Lucie

    2009-01-01

    In this work, I offer a unified analysis of all the constructions that involve a reflexive clitic SE in Slavic and Romance languages. Next to canonical constructions, in which the reflexive clitic semantically identifies the two arguments of a transitive verb, cf. "John" SE "wash" means "John washes himself," there are constructions in which it is…

  6. Reflexive Clitics in the Slavic and Romance Languages. A Comparative View from an Antipassive Perspective

    ERIC Educational Resources Information Center

    Medova, Lucie

    2009-01-01

    In this work, I offer a unified analysis of all the constructions that involve a reflexive clitic SE in Slavic and Romance languages. Next to canonical constructions, in which the reflexive clitic semantically identifies the two arguments of a transitive verb, cf. "John" SE "wash" means "John washes himself," there are constructions in which it is…

  7. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... in a red and white pattern (see Federal Motor Vehicle Safety Standard No. 108 (49 CFR 571.108), S5.7... 49 Transportation 5 2013-10-01 2013-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December...

  8. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... in a red and white pattern (see Federal Motor Vehicle Safety Standard No. 108 (49 CFR 571.108), S5.7... 49 Transportation 5 2012-10-01 2012-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December...

  9. The Effect of the 226-Hz Probe Level on Contralateral Acoustic Stapedius Reflex Thresholds

    ERIC Educational Resources Information Center

    Day, Jessica E.; Feeney, M. Patrick

    2008-01-01

    Purpose: The purpose of this study was to examine the effect of the 226-Hz probe level on the acoustic stapedius reflex threshold. Method: Contralateral reflex thresholds for a 1000-Hz pure-tone stimulus were obtained from 40 young adults with normal hearing using an experimental system at four 226-Hz probe levels (70, 75, 80, and 85 dB SPL) with…

  10. The Modified Blink Reflex and individual Differences in Speed of Processing.

    ERIC Educational Resources Information Center

    Smyth, Mary; Anderson, Mike; Hammond, Geoff

    1999-01-01

    Studied a new method of measuring speed of processing, the modified blink reflex (MBR), in 2 experiments involving 57 adults. Findings are consistent with the view that interconnecting pathways allow higher level processing of a tone to prime the lower-level reflex pathway. Discusses implications for MBR and measurement of speed of processing.…

  11. Prevalence of Persistent Primary Reflexes and Motor Problems in Children with Reading Difficulties

    ERIC Educational Resources Information Center

    McPhillips, M.; Sheehy, N.

    2004-01-01

    It has been shown that some children with reading difficulties have underlying developmental delay and that this may be related to the persistence of primary reflexes. This study investigated the prevalence of persistent primary reflexes in the ordinary primary school population and how this related to other cognitive and social factors. Three…

  12. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... in a red and white pattern (see Federal Motor Vehicle Safety Standard No. 108 (49 CFR 571.108), S5.7... 49 Transportation 5 2014-10-01 2014-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December...

  13. Temporal facilitation of spastic stretch reflexes following human spinal cord injury.

    PubMed

    Hornby, T George; Kahn, Jennifer H; Wu, Ming; Schmit, Brian D

    2006-03-15

    Recent evidence suggests that alterations in ionic conductances in spinal motoneurones, specifically the manifestation of persistent inward currents, may be partly responsible for the appearance of hyperexcitable reflexes following spinal cord injury (SCI). We hypothesized that such alterations would manifest as temporal facilitation of stretch reflexes in human SCI. Controlled, triangular wave, ankle joint rotations applied at variable velocities (30-120 deg s(-1)) and intervals between stretches (0.25-5.0 s) were performed on 14 SCI subjects with velocity-dependent, hyperexcitable plantarflexors. Repeated stretch elicited significant increases in plantarflexion torques and electromyographic (EMG) activity from the soleus (SOL) and medial gastrocnemius (MG). At higher velocities (> or = 90 deg s(-1)), reflex torques declined initially, but subsequently increased to levels exceeding the initial response, while mean EMG responses increased throughout the joint perturbations. At lower velocities (< or = 60 deg s(-1)), both joint torques and EMGs increased gradually. Throughout a range of angular velocities, reflex responses increased significantly only at intervals < or = 1 s between stretches and following at least four rotations. Ramp-and-hold perturbations used to elicit tonic stretch reflexes revealed significantly prolonged EMG responses following one or two triangular stretches, as compared to single ramp-and-hold excursions. Post hoc analyses revealed reduced reflex facilitation in subjects using baclofen to control spastic behaviours. Evidence of stretch reflex facilitation post-SCI may reflect changes in underlying neuronal properties and provide insight into the mechanisms underlying spastic reflexes. PMID:16540600

  14. Processing Reflexives in a Second Language: The Timing of Structural and Discourse-Level Constraints

    ERIC Educational Resources Information Center

    Felser, Claudia; Cunnings, Ian

    2012-01-01

    We report the results from two eye-movement monitoring experiments examining the processing of reflexive pronouns by proficient German-speaking learners of second language (L2) English. Our results show that the nonnative speakers initially tried to link English argument reflexives to a discourse-prominent but structurally inaccessible antecedent,…

  15. Second Language Acquisition of Reflexive Verbs in Russian by L1 Speakers of English

    ERIC Educational Resources Information Center

    Alexieva, Petia Dimitrova

    2012-01-01

    This dissertation examines the process of acquisition of semantic classes of reflexive verbs (RVs) in Russian by L2 learners with a native language English. The purpose of this study is to bridge the gap between current linguistic knowledge and the pedagogical literature existing in English on reflexives in Russian. RVs are taught partially and…

  16. Discontinuation of Reflex Testing of Stool Samples for Vancomycin-Resistant Enterococci Resulted in Increased Prevalence

    PubMed Central

    Bodily, Mandy; McMullen, Kathleen M.; Russo, Anthony J.; Kittur, Nupur D.; Hoppe-Bauer, Joan; Warren, David K.

    2015-01-01

    Discontinuation of reflex testing stool submitted for Clostridium difficile testing for vancomycin-resistant enterococci (VRE) led to an increase of patients with healthcare-associated VRE bacteremia and bacteriuria (2.1 versus 3.6 per 10,000 patient days; p<0.01 ). Cost-benefit analysis showed reflex screening and isolation of VRE reduced hospital costs. PMID:23838226

  17. 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…

  18. Spinal Reflex Arc Excitability Corresponding to the Vastus Medialis Obliquus and Vastus Medialis Longus Muscles

    PubMed Central

    Tanino, Yoshitsugu; Suzuki, Toshiaki

    2014-01-01

    [Purpose] The gross morphology of the vastus medialis (VM) muscle has been thoroughly described. However, there is insufficient evidence of physiological differentiation between the VM obliquus (VMO) and VM longus (VML). To elucidate spinal reflex arc excitability in two divisions of the VM, we compared H-reflexes and T-waves in VMO and VML. [Subjects] Twenty-three healthy male volunteers participated in this study. [Methods] The H-reflex was evoked from the VMO and VML by electrical stimulation of the femoral nerve during knee extension at 10% maximal voluntary isometric contraction. Also, the patellar tendon was tapped by an examiner using an electrical tendon hammer, and a component of the compound muscle action potential (T-wave) was recorded. [Results] The configurations of the H-reflex and T-wave were sharp and slow in VMO and VML, respectively. No significant differences in the amplitudes of the H-reflexes and T-waves were observed between VMO and VML. The durations of VML H-reflexes and T-waves were significantly longer than those in VMO. [Conclusion] Spinal reflex arc excitability corresponding to VMO and VML was similar. However, the configurations and durations of the H-reflex and T-wave were differentiated with electromyography. On the basis of these findings, we suggest that VMO and VML are electrophysiologically distinct entities. PMID:24567685

  19. 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…

  20. Erecting Closets and Outing Ourselves: Uncomfortable Reflexivity and Community-Based Research

    ERIC Educational Resources Information Center

    Reed, Sarah J.; Miller, Robin Lin; Nnawulezi, Nkiru; Valenti, Maria T.

    2012-01-01

    Feminist scholars and community psychologists have argued that reflexivity is a necessary component to conducting socially conscious research. Reflexivity, however, is rarely evident in community psychology. In this article, we share the uncomfortable realities that surfaced during a community-based research project in which we adapted and…

  1. On reflexivity and the conduct of the self in everyday life: reflections on Bourdieu and Archer.

    PubMed

    Akram, Sadiya; Hogan, Anthony

    2015-12-01

    This article provides a critique of the concept of reflexivity in social theory today and argues against the tendency to define agency exclusively in terms of reflexivity. Margaret Archer, in particular, is highlighted as a key proponent of this thesis. Archer argues that late modernity is characterized by reflexivity but, in our view, this position neglects the impact of more enduring aspects of agency, such as the routinization of social life and the role of the taken-for-granted. These concepts were pivotal to Bourdieu and Giddens' theorization of everyday life and action and to Foucault's understanding of technologies of the self. We offer Bourdieu's habitus as a more nuanced approach to theorizing agency, and provide an alternative account of reflexivity. Whilst accepting that reflexivity is a core aspect of agency, we argue that it operates to a backdrop of the routinization of social life and operates from within and not outside of habitus. We highlight the role of the breach in reflexivity, suggesting that it opens up a critical window for agents to initiate change. The article suggests caution in over-ascribing reflexivity to agency, instead arguing that achieving reflexivity and change is a difficult and fraught process, which has emotional and moral consequences. The effect of this is that people often prefer the status quo, rather than to risk change and uncertainty. PMID:26434736

  2. Erecting Closets and Outing Ourselves: Uncomfortable Reflexivity and Community-Based Research

    ERIC Educational Resources Information Center

    Reed, Sarah J.; Miller, Robin Lin; Nnawulezi, Nkiru; Valenti, Maria T.

    2012-01-01

    Feminist scholars and community psychologists have argued that reflexivity is a necessary component to conducting socially conscious research. Reflexivity, however, is rarely evident in community psychology. In this article, we share the uncomfortable realities that surfaced during a community-based research project in which we adapted and…

  3. Reflexivity and the Politics of Knowledge: Researchers as "Brokers" and "Translators" of Educational Development

    ERIC Educational Resources Information Center

    Sriprakash, Arathi; Mukhopadhyay, Rahul

    2015-01-01

    This paper interrogates the ways in which "reflexivity" has proliferated as a normative methodological discourse in the field of international and comparative education. We argue that the dominant approach to reflexivity foregrounds the standpoints of researchers and their subjects in a way that does not attend to the situated,…

  4. Spinal reflex arc excitability corresponding to the vastus medialis obliquus and vastus medialis longus muscles.

    PubMed

    Tanino, Yoshitsugu; Suzuki, Toshiaki

    2014-01-01

    [Purpose] The gross morphology of the vastus medialis (VM) muscle has been thoroughly described. However, there is insufficient evidence of physiological differentiation between the VM obliquus (VMO) and VM longus (VML). To elucidate spinal reflex arc excitability in two divisions of the VM, we compared H-reflexes and T-waves in VMO and VML. [Subjects] Twenty-three healthy male volunteers participated in this study. [Methods] The H-reflex was evoked from the VMO and VML by electrical stimulation of the femoral nerve during knee extension at 10% maximal voluntary isometric contraction. Also, the patellar tendon was tapped by an examiner using an electrical tendon hammer, and a component of the compound muscle action potential (T-wave) was recorded. [Results] The configurations of the H-reflex and T-wave were sharp and slow in VMO and VML, respectively. No significant differences in the amplitudes of the H-reflexes and T-waves were observed between VMO and VML. The durations of VML H-reflexes and T-waves were significantly longer than those in VMO. [Conclusion] Spinal reflex arc excitability corresponding to VMO and VML was similar. However, the configurations and durations of the H-reflex and T-wave were differentiated with electromyography. On the basis of these findings, we suggest that VMO and VML are electrophysiologically distinct entities. PMID:24567685

  5. Interpretation of English Reflexives by Adolescent Speakers of Serbo-Croatian.

    ERIC Educational Resources Information Center

    Bennett, Susan

    1994-01-01

    In a study of first-language transfer and second-language (L2) acquisition of reflexive binding, the interpretation of English reflexives by native speakers of Serbo-Croatian was investigated using two types of written sentence comprehension tasks. Results support the transfer hypothesis and suggest learners have access to Universal Grammar in L2…

  6. Same Source, Same Target, Different Paths: From "Person" to Reflexive in Umpithamu and Other Paman Languages

    ERIC Educational Resources Information Center

    Verstraete, Jean-Christophe

    2008-01-01

    This study analyses a case of parallel grammaticalization in five genetically related languages, with a lexical source meaning "person" developing to a grammatical function of reflexive marking. Although not typologically unusual, this case is special because, in spite of the overall parallelism, the resulting reflexive markers are located in…

  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. The tibialis anterior reflex in healthy subjects and in L5 radicular compression.

    PubMed Central

    Stam, J

    1988-01-01

    Phasic stretch reflexes were evoked in the tibialis anterior (TA) muscle, by tapping the dorsal side of the foot with a hand-held reflex hammer. The responses were recorded by means of surface electrodes. The TA reflex was examined in 70 healthy subjects and in 18 patients with L5 radicular compression. In 58 (83%) of the healthy subjects the reflex could be recorded bilaterally, in eight (11%) subjects no reflex was found on either side, and in four (6%) it was absent in one leg. Simultaneous recordings from the gastrocnemius-soleus showed that TA responses were not caused by volume conduction from that muscle. In the 18 patients with L5 radicular compression the TA reflex was absent on the affected side 13 times (72%) and present bilaterally in the other five cases. If asymmetry of the reflex (unilateral absence) is considered as a test for the presence of L5 radicular compression, the likelihood ratio for a positive test is 12.0, and for a negative test 0.3. The examination of the TA reflex is easily performed and can be useful in the diagnosis of L5 radicular compression. PMID:3361331

  9. 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…

  10. Aging alters muscle reflex control of autonomic cardiovascular responses to rhythmic contractions in humans.

    PubMed

    Sidhu, Simranjit K; Weavil, Joshua C; Venturelli, Massimo; Rossman, Matthew J; Gmelch, Benjamin S; Bledsoe, Amber D; Richardson, Russell S; Amann, Markus

    2015-11-01

    We investigated the influence of aging on the group III/IV muscle afferents in the exercise pressor reflex-mediated cardiovascular response to rhythmic exercise. Nine old (OLD; 68 ± 2 yr) and nine young (YNG; 24 ± 2 yr) males performed single-leg knee extensor exercise (15 W, 30 W, 80% max) under control conditions and with lumbar intrathecal fentanyl impairing feedback from group III/IV leg muscle afferents. Mean arterial pressure (MAP), cardiac output, leg blood flow (QL), systemic (SVC) and leg vascular conductance (LVC) were continuously determined. With no hemodynamic effect at rest, fentanyl blockade during exercise attenuated both cardiac output and QL ?17% in YNG, while the decrease in cardiac output in OLD (?5%) was significantly smaller with no impact on QL (P = 0.8). Therefore, in the face of similar significant ?7% reduction in MAP during exercise with fentanyl blockade in both groups, LVC significantly increased ?11% in OLD, but decreased ?8% in YNG. The opposing direction of change was reflected in SVC with a significant ?5% increase in OLD and a ?12% decrease in YNG. Thus while cardiac output seems to account for the majority of group III/IV-mediated MAP responses in YNG, the impact of neural feedback on the heart may decrease with age and alterations in SVC become more prominent in mediating the similar exercise pressor reflex in OLD. Interestingly, in terms of peripheral hemodynamics, while group III/IV-mediated feedback plays a clear role in increasing LVC during exercise in the YNG, these afferents seem to actually reduce LVC in OLD. These peripheral findings may help explain the limited exercise-induced peripheral vasodilation often associated with aging. PMID:26386110

  11. Facilitation of the swallowing reflex with bilateral afferent input from the superior laryngeal nerve.

    PubMed

    Takahashi, Kojiro; Shingai, Tomio; Saito, Isao; Yamamura, Kensuke; Yamada, Yoshiaki; Kitagawa, Junichi

    2014-03-01

    To determine the cooperative effect of laryngeal afferent signals on the swallowing reflex, we examined whether afferent signals originating from the left and right superior laryngeal nerve (SLN) modulates elicitation of the swallowing reflex in urethane-anesthetized rats. Mylohyoid electromyographic activity was recorded to quantify the swallowing reflex. The onset latency of the swallowing reflex and the time intervals between successive swallows were used to quantify and compare the effects of unilateral and bilateral electrical stimulations of the SLN. The mean latency of the first swallow and the mean time interval between swallows evoked with low frequency stimulation were both significantly different between unilateral and bilateral stimulations of the SLN. These findings suggest that facilitatory effect of afferent signals originating from the SLN bilaterally increase the motoneuronal activity in the medullary swallowing center and enhance the swallowing reflex. PMID:24462841

  12. [Photic sneeze reflex or autosomal dominant compelling helio-ophthalmic outburst syndrome].

    PubMed

    García-Moreno, J M

    2006-01-01

    Sneeze is an ubiquitous phenomenon that happens to everyone. In spite of this, little attention has been paid to it, among medical literature in general, and even less in neurologic texts. A curious entity, called photic sneeze reflex, solar sneeze reflex, light sneeze reflex or autosomal dominant compelling helio-ophthalmic outburst syndrome, known perhaps since ancient Greek, has been scarcely described in the scientific literature, mainly as clinical notes and letters to the editor, but in a detailed way, we can find just a few reports. This reflex appears when subjects are exposed suddenly to intense sunlight and it consists of long incoercible sneeze bursts. It is usually ignored by its sufferers, who report it as a curiosity or a minor complaint, and its importance has been neglected in spite of its hereditary nature and its apparently high prevalence. We review the history, epidemiology, genetics, neuroanatomy, neurophysiology and physiopathology of this reflex hereditary response. PMID:16525923

  13. When planning results in loss of control: intention-based reflexivity and working-memory

    PubMed Central

    Meiran, Nachshon; Cole, Michael W.; Braver, Todd S.

    2012-01-01

    In this review, the authors discuss the seemingly paradoxical loss of control associated with states of high readiness to execute a plan, termed “intention-based reflexivity.” The review suggests that the neuro-cognitive systems involved in the preparation of novel plans are different than those involved in preparation of practiced plans (i.e., those that have been executed beforehand). When the plans are practiced, intention-based reflexivity depends on the prior availability of response codes in long-term memory (LTM). When the plans are novel, reflexivity is observed when the plan is pending and the goal has not yet been achieved. Intention-based reflexivity also depends on the availability of working-memory (WM) limited resources and the motivation to prepare. Reflexivity is probably related to the fact that, unlike reactive control (once a plan is prepared), proactive control tends to be relatively rigid. PMID:22586382

  14. Reflexive anaphor resolution in spoken language comprehension: structural constraints and beyond

    PubMed Central

    Clackson, Kaili; Heyer, Vera

    2014-01-01

    We report results from an eye-tracking during listening study examining English-speaking adults’ online processing of reflexive pronouns, and specifically whether the search for an antecedent is restricted to syntactically appropriate positions. Participants listened to a short story where the recipient of an object was introduced with a reflexive, and were asked to identify the object recipient as quickly as possible. This allowed for the recording of participants’ offline interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our offline results show that the ultimate interpretation for reflexives was constrained by binding principles, the response time, and eye-movement data revealed that during processing participants were temporarily distracted by a structurally inappropriate competitor antecedent when this was prominent in the discourse. These results indicate that in addition to binding principles, online referential decisions are also affected by discourse-level information. PMID:25191290

  15. Reflexive anaphor resolution in spoken language comprehension: structural constraints and beyond.

    PubMed

    Clackson, Kaili; Heyer, Vera

    2014-01-01

    We report results from an eye-tracking during listening study examining English-speaking adults' online processing of reflexive pronouns, and specifically whether the search for an antecedent is restricted to syntactically appropriate positions. Participants listened to a short story where the recipient of an object was introduced with a reflexive, and were asked to identify the object recipient as quickly as possible. This allowed for the recording of participants' offline interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our offline results show that the ultimate interpretation for reflexives was constrained by binding principles, the response time, and eye-movement data revealed that during processing participants were temporarily distracted by a structurally inappropriate competitor antecedent when this was prominent in the discourse. These results indicate that in addition to binding principles, online referential decisions are also affected by discourse-level information. PMID:25191290

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

    NASA Astrophysics Data System (ADS)

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

    1987-05-01

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

  17. 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

  18. Levodopa raises objective pain threshold in Parkinson's disease: a RIII reflex study

    PubMed Central

    Gerdelat?Mas, A; Simonetta?Moreau, M; Thalamas, C; Ory?Magne, F; Slaoui, T; Rascol, O; Brefel?Courbon, C

    2007-01-01

    Background Patients suffering from Parkinson's disease (PD) describe painful sensations that could be related to neuropathic pain. Experimental data have indicated the involvement of basal ganglia and dopaminergic pathways in central nociceptive processing. Aim The objective of this study was to assess and compare the effect of levodopa on the objective pain threshold in patients with PD and healthy subjects. Methods The objective pain threshold was assessed by the nociceptive flexion reflex (RIII) in 13 PD patients and 10 healthy subjects. Patients and healthy subjects were evaluated under two randomised conditions: with levodopa (ON) and without (OFF). Results Levodopa significantly increased the RIII threshold of PD patients (6.9 (1.2)?mA in the OFF condition vs 8 (1.1)?mA in the ON position; p?=?0.02). RIII threshold was significantly lower in PD patients than in healthy subjects in the OFF condition (6.9 (1.2)?mA vs 9.7 (3.4)?mA; p?=?0.02). RIII threshold did not change after levodopa administration in healthy subjects. Conclusion These results provide evidence of a dopaminergic modulation of objective pain threshold in PD patients. In addition, the decrease in RIII threshold in PD patients, in the OFF condition, compared with controls, confirms the existence of an objective pain perception disturbance in PD. PMID:17504881

  19. Neural mechanisms of reflex facilitation and inhibition of gastric motility to stimulation of various skin areas in rats.

    PubMed Central

    Kametani, H; Sato, A; Sato, Y; Simpson, A

    1979-01-01

    1. Experiments were performed on chloralose-urethane anaesthetized rats to determine the involvement of extrinsic gastric autonomic nerves in reflex facilitation and inhibition of gastric motility when mechanical nociceptive stimulation was delivered to either hind paw or abdominal skin, respectively. 2. After bilaterally sectioning the splanchnic nerves in vagal intact animals, the reflex facilitation of gastric motility produced by hind paw stimulation persisted, but the reflex inhibition previously produced by abdominal skin stimulation disappeared. 3. Hind paw stimulation increased efferent activity of the gastric branch of the vagus nerve, but stimulation of abdominal skin had little influence. 4. Bilateral vagotomy in splanchnic nerve intact animals did not influence the gastric reflex inhibition by abdominal skin stimulation, but either abolished gastric reflex facilitation produced by hind paw stimulation or reversed the reflex facilitation response to slight reflex inhibition. 5. Efferent activity of the gastric sympathetic nerve was greatly increased by abdominal skin stimulation, and was either slightly increased or not influenced by hind paw stimulation. 6. It was concluded that reflex increase of efferent activity of the gastric vagi was responsible for the gastric motility facilitation produced by hind paw stimulation, and also that reflexly increased efferent activity of the gastric sympathetic nerves resulted in gastric motility inhibition produced by abdominal skin stimulation. It is suggested efferents are inhibitory. 7. After spinal transection at the cervical level, the reflex facilitation of gastric motility previously produced by stimulation of a hind paw was completely abolished, or reversed to slight reflex inhibition, while reflex inhibition of gastric motility produced by stimulation of abdominal skin remained. It was concluded that the gastric reflex inhibition was a spinal reflex. 8. Interaction between reflex facilitation and inhibition of gastric motility during simultaneous stimulation of both hind paws and abdominal skin was observed as partial cancellation of each effect by the other. However, sympathetic reflex inhibition of gastric motility seemed to be much stronger than the vagal reflex facilitatory effect. PMID:512950

  20. Respiratory kinematic and airflow differences between reflex and voluntary cough in healthy young adults

    PubMed Central

    Brandimore, Alexandra E.; Troche, Michelle S.; Huber, Jessica E.; Hegland, Karen W.

    2015-01-01

    Background: Cough is a defensive behavior that can be initiated in response to a stimulus in the airway (reflexively), or on command (voluntarily). There is evidence to suggest that physiological differences exist between reflex and voluntary cough; however, the output (mechanistic and airflow) differences between the cough types are not fully understood. Therefore, the aims of this study were to determine the lung volume, respiratory kinematic, and airflow differences between reflex and voluntary cough in healthy young adults. Methods: Twenty-five participants (14 female; 18–29 years) were recruited for this study. Participants were evaluated using respiratory inductance plethysmography calibrated with spirometry. Experimental procedures included: (1) respiratory calibration, (2) three voluntary sequential cough trials, and (3) three reflex cough trials induced with 200 μM capsaicin. Results: Lung volume initiation (LVI; p = 0.003) and lung volume excursion (LVE; p < 0.001) were significantly greater for voluntary cough compared to reflex cough. The rib cage and abdomen significantly influenced LVI for voluntary cough (p < 0.001); however, only the rib cage significantly impacted LVI for reflex cough (p < 0.001). LVI significantly influenced peak expiratory flow rate (PEFR) for voluntary cough (p = 0.029), but not reflex cough (p = 0.610). Discussion: Production of a reflex cough results in significant mechanistic and airflow differences compared to voluntary cough. These findings suggest that detection of a tussigenic stimulus modifies motor aspects of the reflex cough behavior. Further understanding of the differences between reflex and voluntary cough in older adults and in persons with dystussia (cough dysfunction) will be essential to facilitate the development of successful cough treatment paradigms. PMID:26500560

  1. Amplification of background EMG activity affects the interpretation of H-reflex gain.

    PubMed

    Tahayori, Behdad; Kitano, Koichi; Hong, Siang L; Koceja, David M

    2010-12-01

    In many H-reflex studies, the modulation of the H-reflex is usually compared relative to the normal EMG activity within the muscle. Such comparisons enable the investigators to infer whether the change in the amplitude of the H-reflex was independent of normally occurring muscle activity. This interpretation of the H-reflex is regarded as H-reflex gain, a popular dependent variable in human H-reflex studies. However, in many studies to date, the muscle activity level has been determined from the same EMG signal from which the H-reflex is recorded. This leads to an important methodological consideration: measuring the ongoing normal EMG activity from the same signal might result in an inaccurate measurement, since this EMG signal will need to be minimally amplified to capture the synchronous volley of the H-reflex amplitude. In this study we examined this possibility and found that comparing the EMG activity level from the seated position to standing position yields different results (on average 8.03% in the measurement of the increase of muscle activity). This difference was both dependent on the task and also on the EMG instrumentation used. To solve this problem we suggest the bifurcation of the EMG signal from the recording electrodes with differential amplification of the signal. With this method, both the naturally occurring muscle activity and the H-reflex signal are collected from the same area of the muscle and a more accurate measurement of the H-reflex gain will be yielded. PMID:20708409

  2. Trigeminal autonomic pathways involved in nociception-induced reflex cardiovascular responses.

    PubMed

    Allen, G V; Pronych, S P

    1997-04-18

    Reflex cardiovascular responses elicited by noxious oro-facial stimulation are well known but the neural pathways that underlie trigeminal cardiovascular reflex reactions remain to be elucidated. In previous studies, we have shown that noxious electrical stimulation of the mandibular incisor in the anesthetized rat elicits increases in mean arterial blood pressure and heart rate (Allen, G.V., Barbrick, B. and Esser, M.J., Trigeminal parabrachial connections: possible pathway for nociception-induced cardiovascular reflex responses, Brain Res., 715 (1996) 125-135). In this study, microinjections of the presynaptic blocker, cobalt chloride, or the anesthetic agent, lidocaine, were made into selected brainstem sites to identify neural pathways that are involved in mediation of the reflex pressor responses. Ipsilateral and bilateral injections of chemical blocker into the dorsomedial spinal trigeminal nucleus, pars caudalis, lateral parabrachial nucleus and the rostral ventral lateral medulla/caudal A5 region attenuated the reflex cardiovascular response. Bilateral injections of cobalt chloride into the dorsomedial subnucleus caudalis resulted in 70-100% attenuation of the reflex pressor response. Bilateral injections of cobalt chloride and/or lidocaine into the lateral parabrachial nucleus or the rostral ventral lateral medulla/A5 region resulted in 43-57% and 44-100% attenuation of the reflex pressor response, respectively. There were no significant differences in the degree or duration of attenuation of the reflex pressor responses produced by cobalt chloride compared to that produced by lidocaine injections. The reflex pressor responses usually returned to baseline levels approximately 60 min following injection of the chemical blocker substance. The results indicate that noxious electrical stimulation of the mandibular incisor elicits a reflex increase in mean arterial blood pressure which is initially mediated in the dorsomedial spinal trigeminal nucleus, pars caudalis and is subsequently mediated in the lateral parabrachial nucleus and the rostral ventral lateral medulla/caudal A5 region. PMID:9134984

  3. The differential role of motor cortex in the stretch reflex modulation induced by changes in environmental mechanics and verbal instruction

    PubMed Central

    Shemmell, Jonathan; An, Je Hi; Perreault, Eric J.

    2009-01-01

    The motor cortex assumes an increasingly important role in higher mammals relative to that in lower mammals. This is true to such an extent that the human motor cortex is deeply involved in reflex regulation and it is common to speak of “transcortical reflex loops”. Such loops appear to add flexibility to the human stretch reflex, once considered to be immutable, allowing it to adapt across a range of functional tasks. However, the purpose of this adaptation remains unclear. A common proposal is that stretch reflexes contribute to the regulation of limb stability; increased reflex sensitivity during tasks performed in unstable environments supports this hypothesis. Alternatively, prior to movement onset, stretch reflexes can assist an imposed stretch, opposite to what would be expected from a stabilizing response. Here we show that stretch reflex modulation in tasks that require changes in limb stability is mediated by motor cortical pathways, and that these differ from pathways contributing to reflex modulation that depends on how the subject is instructed to react to an imposed perturbation. By timing muscle stretches such that the modulated portion of the reflex occurred within a cortical silent period induced by transcranial magnetic stimulation, we abolished the increase in reflex sensitivity observed when individuals stabilized arm posture within a compliant environment. Conversely, reflex modulation caused by altered task instruction was unaffected by cortical silence. These results demonstrate that task-dependent changes in reflex function can be mediated through multiple neural pathways and that these pathways have task specific roles. PMID:19846713

  4. 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

  5. Top-down modulation of prepulse inhibition of the startle reflex in humans and rats.

    PubMed

    Li, Liang; Du, Yi; Li, Nanxin; Wu, Xihong; Wu, Yanhong

    2009-09-01

    Prepulse inhibition (PPI) is the attenuation of the startle reflex when the sudden intense startling stimulus is shortly preceded by a weaker, non-startling sensory stimulus (prepulse). PPI reflects a protective function of reducing disruptive influences to the processing of prepulse signals and is recognized as a model of sensorimotor gating. In humans, PPI is modulated by both attentional and emotional responses to prepulse, indicating that this early-stage gating is top-down modulated by higher-order cognitive processes. Recent studies have confirmed top-down modulation of PPI in animals, because PPI in rats is enhanced by auditory fear conditioning and perceived separation between fear-conditioned prepulse and masker. This review summarizes recent studies of top-down modulation of PPI conducted in humans and those in rats. Since both baseline PPI and attentional modulation of PPI in patients with schizophrenia are impaired, and both baseline PPI and conditional modulation of PPI in rats with isolation rearing are impaired, this review emphasizes that investigation of top-down modulation of PPI is critical for establishing new animal models for studying both cognitive features and neural bases of schizophrenia. Deficits in either baseline PPI or attentional modulation of PPI in either patients with attention-deficit/hyperactivity disorder (ADHD) or ADHD-modeling rats are also discussed. PMID:19747594

  6. 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.

  7. 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

  8. 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.

  9. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    SciTech Connect

    Toader, E.I.; Covlea, V.N.

    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.

  10. Pupillary light reflex to light inside the natural blind spot.

    PubMed

    Miyamoto, Kentaro; Murakami, Ikuya

    2015-01-01

    When a light stimulus covers the human natural blind spot (BS), perceptual filling-in corrects for the missing information inside the BS. Here, we examined whether a filled-in surface of light perceived inside the BS affects the size of the short-latency pupillary light reflex (PLR), a pupil response mediated by a subcortical pathway for unconscious vision. The PLR was not induced by a red surface that was physically absent but perceptually filled-in inside the BS in the presence of a red ring surrounding it. However, a white large disk covering the BS unexpectedly induced a larger PLR than a white ring surrounding the BS border did, even though these two stimuli must be equivalent for the visual system, and trial-by-trial percepts did not predict PLR size. These results suggest that some physiological mechanism, presumably the retinal cells containing the photopigment melanopsin, receives the light projected inside the BS and enhances PLR. PMID:26115182

  11. Olfactory bulbectomy attenuates cardiovascular sympathoexcitatory reflexes in rats.

    PubMed

    Moffitt, Julia A; Grippo, Angela J; Holmes, Philip V; Johnson, Alan Kim

    2002-12-01

    Bilateral removal of the olfactory lobes in rats produces a number of behavioral, endocrine, and neurochemical alterations in the brain. Little is known, however, regarding the effects of this treatment on cardiovascular function and autonomic reflexes. Male Sprague-Dawley rats underwent bilateral surgical ablation of the olfactory bulbs (n = 10) or were sham operated (n = 8). After 3 wk of recovery, animals were instrumented with femoral catheters and a lumbar sympathetic nerve recording electrode. After 24 h of recovery, cardiovascular responses to arterial baroreflex manipulation, air jet stress, and smoke exposure were recorded. Olfactory bulbectomized rats demonstrated attenuated sympathoexcitatory responses to hypotension, air jet stress, and smoke exposure, as well as elevated basal blood pressure, compared with sham-operated rats. These data indicate that the integrity of the olfactory bulbs in rats is important for the elicitation of normal cardiovascular and autonomic responses to a number of evocative stimuli. PMID:12388291

  12. 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.

  13. 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

  14. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    NASA Astrophysics Data System (ADS)

    Toader, E. I.; Covlea, V. N.

    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 5.5eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density ne is as high as 1018m-3, and the electron temperature Te 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.

  15. Oxygen and carbon ions from a reflex discharge ion source

    NASA Astrophysics Data System (ADS)

    Hentschel, R.; Henke, D.

    1992-04-01

    Intense beams of oxygen and carbon ions are of interest for applications in microelectronics and material modification. However, it is often impossible to produce them with usual arc discharge ion sources for a sufficiently long time because of the corrosion or covering of the cathode. The paper shows how the lifetime difficulties can be overcome using a strontium oxide platinum cathode in connection with oxygen or carbon dioxide as working gas. Beams in the 50 mA range with a share of 40% O+ or 30% C+ are steadily obtained from a compact reflex discharge ion source. A cathode lifetime of more than 60 h has been reached at a discharge current of 8 A.

  16. 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

  17. 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.

  18. Freidreich's ataxia with retained reflexes: a phenotype and genotype correlation.

    PubMed

    Verma, Rajesh; Gupta, Mani

    2012-01-01

    An 18-year-old lady had presented to us with insidious onset progressive gait ataxia of 5-year duration. Her sister had similar complaints and type 1 diabetes mellitus. Examination revealed, gait ataxia, impaired tandem gait, babinski sign and severe swaying on testing for Romberg's sign. All deep tendon reflexes were exaggerated. On investigations, there was no evidence for diabetes mellitus or nutritional deficiencies. Electrocardiogram and echocardiogram were normal. Magnetic spine resonance showed marked atrophy of cervical cord with normal cerebellum. The genetic testing disclosed expanded GAA repeat length on both alleles of FXN gene. The GAA repeat length on both alleles was much less than mean length observed in Friedreich's ataxia. This case highlights how strongly the genotype influences the neurological and systemic manifestations as well as severity of disease in Friedreich's ataxia. PMID:23242090

  19. Specification of Extended Reflexive Ontologies in the context of CDSS.

    PubMed

    Sanchez, Eider; Toro, Carlos; Graña, Manuel; Sanín, Cesar; Szczerbicki, Edward

    2014-01-01

    Decision recommendations are a set of alternative options for clinical decisions (e.g. diagnosis, prognosis, treatment selection, follow-up and prevention) that are provided to decision makers by knowledge-based Clinical Decision Support Systems (k-CDSS) as aids. We propose to follow a reasoning over domain approach for the generation of decision recommendations, by gathering and inferring conclusions from production rules. In order to rationalize our approach we present a specification that will sustain the logic models supported in the Knowledge Bases we use for persistence. We introduce first the underlying knowledge model and then the necessary extensions that will convey towards the solution of the reported needs. The starting point of our approach is the work of Toro et al. [13] on Reflexive Ontologies (RO). We also propose an extension of RO, by including the handling and reasoning that production rules provide. Our approach speeds-up the recommendation generation process. PMID:25488229

  20. Pupillary light reflex to light inside the natural blind spot

    PubMed Central

    Miyamoto, Kentaro; Murakami, Ikuya

    2015-01-01

    When a light stimulus covers the human natural blind spot (BS), perceptual filling-in corrects for the missing information inside the BS. Here, we examined whether a filled-in surface of light perceived inside the BS affects the size of the short-latency pupillary light reflex (PLR), a pupil response mediated by a subcortical pathway for unconscious vision. The PLR was not induced by a red surface that was physically absent but perceptually filled-in inside the BS in the presence of a red ring surrounding it. However, a white large disk covering the BS unexpectedly induced a larger PLR than a white ring surrounding the BS border did, even though these two stimuli must be equivalent for the visual system, and trial-by-trial percepts did not predict PLR size. These results suggest that some physiological mechanism, presumably the retinal cells containing the photopigment melanopsin, receives the light projected inside the BS and enhances PLR. PMID:26115182