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Sample records for conditioned reflexes

  1. INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES

    E-print Network

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

    INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES DAVID A. JORGENSEN AND LIANA M. S¸EGA Abstract. We show that the conditions defining total reflexivity for modules are independent. In particular, we construct a commutative Noetherian local ring R and a reflexive R-module M such that Exti R(M, R

  2. INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES

    E-print Network

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

    INDEPENDENCE OF THE TOTAL REFLEXIVITY CONDITIONS FOR MODULES reflexivity for modu* *les are independent. In particular, we construct a commutative Noetherian lo* *cal ring R and a reflexive R-module M such that ExtiR(M, R) = 0 for all i > * *0

  3. [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

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

    E-print Network

    Menzel, Randolf - Institut für Biologie

    Research Associative Mechanosensory Conditioning of the Proboscis Extension Reflex in Honeybees of the proboscis extension reflex (PER) in honeybees. In our paradigm, harnessed honeybees learn the elemental learning studies in honeybees. Associative learning is a fundamental property of nervous sys- tems governed

  5. Exercise-induced neuromuscular dysfunction under reflex conditions.

    PubMed

    Kaufman, T; Burke, J R; Davis, J M; Durstine, J L

    2001-06-01

    The purpose of this research was to describe further the effects of exercise-induced muscle damage on reflex sensitivity. The subjects were eight physically active, but untrained males, between the ages of 18 and 29 years. The effects of eccentric and concentric exercise on patellar tendon reflex responses were determined. The 8 week experiment consisted of two, 5 day, test protocols with a 6 week wash-out period between test protocols. Each 5 day test protocol consisted of the following six test sessions: (1) day 1--baseline, (2) day 2 baseline, (3) day 2--immediate post-exercise, and (4-6) days 3-5: 24, 48, and 72 h post-exercise. On day 2, the subjects made either 100 fatiguing concentric or eccentric isotonic contractions using the right leg at 75% of the corresponding repetition maximum values. During each test session, the electromyogram (EMG) and force-time characteristics of basic and conditioned patellar tendon reflex responses were measured. The reflex amplitudes of basic and conditioned patellar tendon reflex responses were decreased following fatiguing concentric exercise. There were no immediate effects of fatiguing eccentric exercise on the basic and conditioned patellar tendon reflex responses, but the EMG amplitudes of these reflex responses were reduced on the days following eccentric exercise. The amount of conditioned patellar tendon reflex facilitation was decreased following the concentric exercise protocol and at 48 h post-eccentric exercise. Our conditioned reflex data suggest that post-exercise changes to the physiological mechanisms that modulate the recruitment gain of the alpha-motoneuron pool may depend upon the type of fatiguing exercise. PMID:11482545

  6. 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…

  7. 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

  8. 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

  9. 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

  10. Journal of Neuroscience Methods 89 (1999) 133140 Classical conditioning of the electrically elicited blink reflex in

    E-print Network

    Timmer, Jens

    1999-01-01

    elicited blink reflex in humans: a new method of data analysis F.X. Glocker a, *, M. Lauk b,c , D. Fo the analysis of classical conditioning of the electrically elicited blink reflex in humans. To optimize. Keywords: Basal ganglia; Blink reflex; Cerebellum; Classical conditioning; Habituation; Motor learning 1

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

    E-print Network

    Inactivation of the Central Nucleus of the Amygdala Abolishes Conditioning-Specific Reflex response (NMR) reflex facilitation, the CE may also be involved in conditioning-specific reflex of posttraumatic stress disorder. Keywords: reflex modification, muscimol, fear conditioning, eyeblink, rabbit Once

  12. 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.

  13. Effect of Rhythmic Arm Movement on Reflexes in the Legs: Modulation of Soleus H-Reflexes and Somatosensory Conditioning

    E-print Network

    Zehr, Paul

    Effect of Rhythmic Arm Movement on Reflexes in the Legs: Modulation of Soleus H-Reflexes of rhythmic arm movement on reflexes in the legs: modulation of soleus H-reflexes and somatosensory reflex excitability during movement. We hypothesized that rhythmic arm movement would alter the gain

  14. Proto Algic VI: Conditioned Yurok Reflexes of Proto Algic Vowels

    E-print Network

    Proulx, Paul

    2004-01-01

    Berman (1982) proposed a loss of vowel length as one of two apparent phonological innovations shared by Wiyot and Yurok, but not Algonquian, implying a Ritwan subgrouping within Algic. However, once the Yurok reflexes of Proto Algic vowels...

  15. 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

  16. Conditioning-specific reflex modification occurs when an unconditionedresponse(UR)ismodifiedinthe absence

    E-print Network

    that conditioning-specific reflex modification (CRM) is a function of both the level of conditioning (Schreurs et al., 1995) and the intensity of the US (Seager, Smith-Bell, & Schreurs, 2003). In addition, CRM can survive, & Schreurs, 2001). More recent evidence from heart rate measurements sug- gests that classical conditioning

  17. 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

  18. 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…

  19. 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

  20. Light conditions affect the roll-induced vestibuloocular reflex in Xenopus laevis tadpoles

    NASA Astrophysics Data System (ADS)

    El-Yamany, Nabil A.

    2008-12-01

    In Xenopus laevis tadpoles, effects of asymmetrical light conditions on the roll-induced vestibuloocular reflex (rVOR) were tested for the developmental period between stage 47 and 49. For comparison, the rVOR was tested in dim- and high-symmetrical light environments. Test parameters were the rVOR gain and rVOR amplitude. Under all light conditions, the rVOR increased from tadpole stage 47 to 49. For all stages, the asymmetrical light field induced the strongest response, the dim light field the weakest one. The response for the left and right eye was identical, even if the tadpoles were tested under asymmetrical light conditions. The experiments can be considered as hints (1) for an age-dependent light sensitivity of vestibular neurons, and (2) for the existence of control systems for coordinated eye movements that has its origin in the proprioceptors of the extraocular eye muscles.

  1. 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.

  2. 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

  3. 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, ...

  4. 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

  5. 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...

  6. 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

  7. [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

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

    NASA Astrophysics Data System (ADS)

    Zou, Dan; Wu, Xihong; Li, Liang

    2005-04-01

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

  9. 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

  10. Activation of the cholinergic system of the striatum improves attention to conditioned reflex stimuli.

    PubMed

    Shapovalova, K B

    1999-01-01

    Chronic experiments were performed on 16 dogs using a model of an operant defensive reflex associated with maintenance of a flexion pose to study the effects of uni- and bilateral microinjections of the acetylcholine agonist carbacholine (0.05-0.4 microg) and the choline receptor blocker scopolamine (0.5 microg) into the dorsolateral part of the head of the caudate nucleus and CM-Pf intralaminar thalamic nuclei. These experiments produced data showing that the cholinergic system of the striatum has an important role in realizing the sensory and motor components of the learned movement. Activation of the cholinergic system of the dorsal striatum led to general calming of behavior and inhibition of intersignal limb elevation and the phasic components of the movement, along with ordering and stabilizing of the pose and an increase in the tonic component of the operant response. This suggests that the cholinergic system of the striatum receives an indirect efferent output via motor structures and takes part in preparing the motor apparatus needed for transferring attention to significant stimuli. Microinjections of scopolamine had the opposite effects. Use of differential signals in the same behavioral model, along with special tests for attention, showed that the cholinergic system of the striatum plays an important role in the sensory control of attention. Activation of the striatal cholinergic system led to a significant improvement in responses to differential signals and defensive signals of intensity 2-3 times slower than normal signals, and these changes were accompanied by clearer responses in special tests for attention. Scopolamine microinjections had the opposite effects. Carbacholine microinjections into the intralaminar thalamic nuclei potentiated the effects of cholinergic activation of the striatum. These data indicate that the dorsal striatum can be regarded not only as a parallel level of information processing, but also as a control system for passing this information to various levels of both sensory and motor structures. One important result of this type of control may be that of improving attention to significant stimuli. PMID:10596785

  11. 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.

  12. [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

  13. BRAIN-COMPUTER INTERFACES & REFLEX CONDITIONING: NEW METHODS FOR RESTORING FUNCTION

    E-print Network

    Valero-Cuevas, Francisco

    at many different neuronal and synaptic sites from the cortex to the spinal cord. New methods are needed to spinal cord injury, cerebral palsy, stroke, amyotrophic lateral sclerosis (ALS), or other chronic circuits of the spinal cord are the final common pathway for motor skills. By operantly conditioning spinal

  14. 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

  15. [The analytical characteristics of the dynamics of interneuronal functional connections during conditioned-reflex activity].

    PubMed

    Kozlov, A P; Shabaev, V V

    1999-01-01

    The dynamics of functional relations between neurons was studied in the frontal cortex of dogs performing reversal conditioning task. To reveal the functionally relevant relationships between the temporal patterns of correlated firing and behavioral events, we developed an original processing technique. The technique included the following procedures: a) isolation of the "coupled spikes" (CS) from simultaneously recorded impulse trains: b) search for the temporal patterns of correlated firings and their classification by clustering single trials with similar temporal distribution of CS; c) assessment of behavioral significance of the identified patterns by evaluation of the probabilities of coincidence of behavioral events and different CS patterns. Significant correlations between impulse trains were revealed in 38 neuronal pairs of 456 analyzed. The effects of change in behavioral context on the CS dynamics during the task performance were found in 87% of neuronal pairs with correlated activity. In 17 pairs the behavioral conditions were identified, under which potentially connected neurons fired independently during all the periods of the behavioral task. The potentialities of the advanced processing technique are discussed. We suggest that this analysis can provide useful information about the temporal distribution of correlated firings under conditions of nonstereotyped behavior, when an animal reacts in the dynamically organized experimental context. PMID:10420556

  16. [The role of uncertainty in the conditioned-reflex learning behavior for selected cardiovascular functions].

    PubMed

    Mechedowa, A J; Hecht, K; Treptow, K; Hecht, T

    1976-01-01

    As a contribution to quantitative analysis of exogenous stress action, the role of probability learning (probability stress, probability affirmation) for selected cardio-vascular functions was studied in 25 albino rats and 8 dogs. It has been shown in the rats learning with probability stress that a dependence exists between stress probability, on the one hand, and conditional-reflectory processes and systolic blood pressure rise, on the other, that is, the pathogenic action of probability stress increases from a probability of p = 1.0 to p = 0.5. An analogous picture was found with the probability affirmation being applied in dogs. While a probability affirmation with p = 1.0 promoted adaptational processes, a value of p = 0.5 led to experimental neurosis, tachycardia and ECG alterations. The results obtained are discussed in context with the information entropy and information theory of emotions. PMID:1035021

  17. A Cartesian Reflex Assessment of Face Processing

    E-print Network

    Massachusetts at Amherst, University of

    3 A Cartesian Reflex Assessment of Face Processing Robert J. Polewan Christopher M. Vigorito. The one introduced here involves what we refer to as a Cartesian reflex paradigm (CRP). With it, we report responses, or more properly, Cartesian reflexes (CRs). As in classical conditioning protocols, response

  18. Reflex epilepsy.

    PubMed

    Espadaler Medina, J M; Espadaler Gamissans, J M; Seoane, J L

    1992-01-01

    We report 3 cases of reflex epilepsy, 2 of them triggered by reading (reading epilepsy) and one by mathematical calculation (epilepsy arithmetics). Electroencephalographic abnormalities predominated in the dominant hemisphere. The pathophysiologic mechanisms involved in this rare form of epilepsy are commented on, particularly the role played by the association of mental concentration and emotional strain. A possible deficiency in GABA-ergic inhibitory synapses would cause a deficit in cortical inhibition. Different drugs have been used successfully in patients with reflex epilepsy. Psychotherapy relieves anxiety and has been shown to be an effective complement to medical treatment. PMID:1320525

  19. 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.

  20. Infant reflexes

    MedlinePLUS

    ... remove the finger causes the grip to tighten. Newborn infants have strong grasps and can almost be lifted ... the baby have? At what age did each infant reflex disappear? What other symptoms are also present (for example, decreased alertness or seizures)?

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

    ERIC Educational Resources Information Center

    Pollard, Carl; Xue, Ping

    1998-01-01

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

  2. Reflexives in Mohawk

    E-print Network

    Bonvillain, Nancy

    1994-01-01

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

  3. 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.

  4. FULL OPERATORS ON REFLEXIVE BANACH SPACES SOTIRIOS KARANASIOS

    E-print Network

    Karanasios, Sotirios

    FULL OPERATORS ON REFLEXIVE BANACH SPACES SOTIRIOS KARANASIOS Published in (Bulletin of the Greek show that all these results are also valid on reflexive Banach spaces. Note that every uniformly convex Banach space is reflexive but not conversely. We show, by giving an example that the condition "T

  5. 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)

  6. 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…

  7. Potentiation of the startle reflex is in line with contingency reversal instructions rather than the conditioning history.

    PubMed

    Mertens, Gaëtan; De Houwer, Jan

    2016-01-01

    In the context of fear conditioning, different psychophysiological measures have been related to different learning processes. Specifically, skin conductance responses (SCRs) have been related to cognitive expectancy learning, while fear potentiated startle (FPS) has been proposed to reflect affective learning that operates according to simple associative learning principles. On the basis of this two level account of fear conditioning we predicted that FPS should be less affected by verbal instructions and more affected by direct experience than SCRs. We tested this hypothesis by informing participants that contingencies would be reversed after a differential conditioning phase. Our results indicate that contingency reversal instructions led to an immediate and complete reversal of FPS regardless of the previous conditioning history. This change was accompanied by similar changes on US expectancy ratings and SCRs. These results conform with an expectancy model of fear conditioning but argue against a two level account of fear conditioning. PMID:26655786

  8. 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

  9. Astronomical Data Reduction Workflows with Reflex

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  10. Emotionally Colorful Reflexive Games

    E-print Network

    Tarasenko, Sergey

    2011-01-01

    This study addresses the matter of reflexive control of the emotional states by means of Reflexive Game Theory (RGT). It is shown how to build a bridge between RGT and emotions. For this purpose the Pleasure-Arousal-Dominance (PAD) model is adopted. The major advantages of RGT are its ability to predict human behavior and unfold the entire spectra of reflexion in the human mind. On the other hand, PAD provides ultimate approach to model emotions. It is illustrated that emotions are reflexive processes and, consequently, RGT fused with PAD model is natural solution to model emotional interactions between people. The fusion of RGT and PAD, called Emotional Reflexive Games (ERG), inherits the key features of both components. Using ERG, we show how reflexive control can be successfully applied to model human emotional states. Up to date, EGR is a unique methodology capable of modeling human reflexive processes and emotional aspects simultaneously.

  11. Farhan Imtiaz Emergence of Reflexive

    E-print Network

    Daraio, Chiara

    Farhan Imtiaz Emergence of Reflexive Behavior from Single Muscle Twitches Master Thesis Bio. In this paper, we explored how basic reflexes(the myotatic reflex, reverse myotatic reflex and recipro- cal inhibition reflex) can be learned through such interaction. In this paper we used single muscle twitches

  12. 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

  13. 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

  14. 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.

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

    E-print Network

    Backus, Bradford Clark

    2005-01-01

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

  16. 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

  17. The influence of muscle spindle discharge on the human H reflex and the monosynaptic reflex in the cat.

    PubMed Central

    Wood, S A; Gregory, J E; Proske, U

    1996-01-01

    1. Experiments were carried out to test the effect of changes in spindle resting discharge on the size of monosynaptic reflexes in the cat and on the H reflex in humans. Resting discharge was altered by contracting the triceps surae muscle at longer (hold-long) or shorter (hold-short) lengths than that at which the reflex was tested. 2. The reflex in the cat was larger after hold-long than after hold-short conditioning, and the difference, after an initial decline, was well maintained. For the human H reflex a similar pattern was observed except that 15 s after muscle conditioning the difference in reflex size had disappeared. 3. Monosynaptic reflex depression immediately after hold-long conditioning, when most of the muscle spindles are silent, was attributed to the high level of spindle discharge during the immediately preceding hold-long period. The time course of this inhibition was too long to be accounted for by presynaptic inhibition. 4. In the cat heteronymous muscle conditioning was used to test whether presynaptic inhibition could be responsible for reflex depression using the synergist muscle pair lateral gastrocnemius-soleus and medial gastrocnemius. Conditioning one of the pair did not affect the reflex in the other, the opposite result to that expected with presynaptic inhibition. A similar experiment in which the triceps H reflex in human subjects was facilitated by a quadriceps volley gave the same result. 5. Thus this study presents evidence that monosynaptic reflexes are depressed by the on-going discharge of muscle spindles in the homonymous muscle, but that this depression does not appear to involve "classical' presynaptic inhibition. PMID:8951729

  18. 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

  19. 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

  20. 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…

  1. Design and Reflexivity.

    ERIC Educational Resources Information Center

    van Toorn, Jan

    1994-01-01

    Argues that design, despite frequently well-intentioned ethical starting-points, has become generalized and rudimentary in its substantive and instrumental choices, and naive in its thinking about its own public role. Argues for a "mental ecology," for a multidimensional realistic reflexivity, which makes possible the recuperation of a practice…

  2. 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.

  3. Spinal reflexes in brain death.

    PubMed

    Beckmann, Yesim; Çiftçi, Yeliz; Incesu, Tülay Kurt; Seçil, Yaprak; Akhan, Galip

    2014-12-01

    Spontaneous and reflex movements have been described in brain death and these unusual movements might cause uncertainties in diagnosis. In this study we evaluated the presence of spinal reflexes in patients who fulfilled the criteria for brain death. Thirty-two (22 %) of 144 patients presented unexpected motor movements spontaneously or during examinations. These patients exhibited the following signs: undulating toe, increased deep tendon reflexes, plantar responses, Lazarus sign, flexion-withdrawal reflex, facial myokymia, neck-arm flexion, finger jerks and fasciculations. In comparison, there were no significant differences in age, sex, etiology of brain death and hemodynamic laboratory findings in patients with and without reflex motor movement. Spinal reflexes should be well recognized by physicians and it should be born in mind that brain death can be determined in the presence of spinal reflexes. PMID:24604683

  4. THE REFLEXIVITY OF A SEGRE PRODUCT OF PROJECTIVE VARIETIES

    E-print Network

    Kaji, Hajime

    THE REFLEXIVITY OF A SEGRE PRODUCT OF PROJECTIVE VARIETIES ( ) ( / ) : , . reflexivity . reflexivity , (reflexivity ). ( , ) . Hefez-Thorup [4] 2 reflexive . [5] , 2 reflexive : , p = 2 P1 Ã?P1 Ã?P1 P7 non-reflexive . [1] , p + 1 Fermat non-reflexive . : Theorem ([2]). Y PN n , r Y , Pm Ã? Y non-reflexive

  5. Corporeal reflexivity and autism.

    PubMed

    Ochs, Elinor

    2015-06-01

    Ethnographic video recordings of high functioning children with autism or Aspergers Syndrome in everyday social encounters evidence their first person perspectives. High quality visual and audio data allow detailed analysis of children's bodies and talk as loci of reflexivity. Corporeal reflexivity involves displays of awareness of one's body as an experiencing subject and a physical object accessible to the gaze of others. Gaze, demeanor, actions, and sotto voce commentaries on unfolding situations indicate a range of moment-by-moment reflexive responses to social situations. Autism is associated with neurologically based motor problems (e.g. delayed action-goal coordination, clumsiness) and highly repetitive movements to self-soothe. These behaviors can provoke derision among classmates at school. Focusing on a 9-year-old girl's encounters with peers on the playground, this study documents precisely how autistic children can become enmeshed as unwitting objects of stigma and how they reflect upon their social rejection as it transpires. Children with autism spectrum disorders in laboratory settings manifest diminished understandings of social emotions such as embarrassment, as part of a more general impairment in social perspective-taking. Video ethnography, however, takes us further, into discovering autistic children's subjective sense of vulnerability to the gaze of classmates. PMID:25939529

  6. 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

  7. Reflexive Planning for Later Life

    ERIC Educational Resources Information Center

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

    2004-01-01

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

  8. 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…

  9. 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

  10. 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.

  11. [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

  12. RANGES OF BIMODULE PROJECTIONS AND REFLEXIVITY

    E-print Network

    RANGES OF BIMODULE PROJECTIONS AND REFLEXIVITY G. K. ELEFTHERAKIS AND I. G. TODOROV Abstract. We develop a general framework for reflexivity in dual Ba- nach spaces, motivated by the question of when the weak* closed linear span of two reflexive masa-bimodules is automatically reflexive. We es- tablish

  13. 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

  14. 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

  15. 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.

  16. Dysphoric milk ejection reflex: A case report

    PubMed Central

    2011-01-01

    Dysphoric Milk Ejection Reflex (D-MER) is an abrupt emotional "drop" that occurs in some women just before milk release and continues for not more than a few minutes. The brief negative feelings range in severity from wistfulness to self-loathing, and appear to have a physiological cause. The authors suggest that an abrupt drop in dopamine may occur when milk release is triggered, resulting in a real or relative brief dopamine deficit for affected women. Clinicians can support women with D-MER in several ways; often, simply knowing that it is a recognized phenomenon makes the condition tolerable. Further study is needed. PMID:21645333

  17. Reflex seizures in Rett syndrome.

    PubMed

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

    2011-12-01

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

  18. [The oculocardiac reflex in blepharoplasties].

    PubMed

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

    2008-08-01

    The oculocardiac reflex (OCR) is a well-known phenomenon in ophthalmic surgery, but is rarely described in aesthetic blepharoplasty surgery. It was first mentioned in 1908 by Ascher and Dagnini. Since then, ophthalmologists and anaesthesiologists have regarded the onset of the oculocardiac reflex as a significant intraoperative problem, which is undermined by several case reports that describe dysrhythmias which have haved caused morbidity and death. Per definition the OCR is caused by ocular manipulation and involves intraoperative bradycardia by a change of 20 beats/minute compared to the preoperative heart rate or any dysrhythmia during the manipulation via a trigeminal-vagal-mediated reflex arc. Having operated on a 48-year-old, healthy woman in our clinic, who underwent a cardiac arrest during the blepharoplasty procedure, followed by a successful resuscitation, we investigated the onset of the OCR in our blepharoplasty patients within the last 3 years. The onset of the OCR was noted in 22 of 110 (20 %) blepharoplasty patients, mainly affecting younger, low-weighted patients operated under local anaesthesia. Awareness and treatment of this potentially life-threatening oculocardiac reflex are necessary. In most cases the onset of the reflex may be avoided by a gentle operation technique and by refraining from severe traction to the muscle or fat pad. The best treatment of a profound bradycardia caused by the OCR is to release tension to the muscle or fat pad in order to permit the heart rate to return to normal. Intraoperative monitoring is of utmost importance. PMID:18716987

  19. 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

  20. Brane Tilings and Reflexive Polygons

    E-print Network

    Amihay Hanany; Rak-Kyeong Seong

    2012-02-06

    Reflexive polygons have attracted great interest both in mathematics and in physics. This paper discusses a new aspect of the existing study in the context of quiver gauge theories. These theories are 4d supersymmetric worldvolume theories of D3 branes with toric Calabi-Yau moduli spaces that are conveniently described with brane tilings. We find all 30 theories corresponding to the 16 reflexive polygons, some of the theories being toric (Seiberg) dual to each other. The mesonic generators of the moduli spaces are identified through the Hilbert series. It is shown that the lattice of generators is the dual reflexive polygon of the toric diagram. Thus, the duality forms pairs of quiver gauge theories with the lattice of generators being the toric diagram of the dual and vice versa.

  1. 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.

  2. Neuromuscular consequences of reflexive covert orienting

    E-print Network

    Crawford, Doug

    Neuromuscular consequences of reflexive covert orienting Brian D Corneil1,2,5, Douglas P Munoz3 are recruited during such reflexive covert orienting in a manner that parallels activity recorded from the superior colliculus (SC). Our results indicate the presence of a brainstem circuit whereby reflexive covert

  3. REFLEXIVE METAPROGRAMMING IN RUBY TUTORIAL PRESENTATION

    E-print Network

    Cunningham, Conrad

    REFLEXIVE METAPROGRAMMING IN RUBY TUTORIAL PRESENTATION H. Conrad Cunningham Department of Computer. It is implemented as an internal (or embedded) DSL [4, 5] using Ruby's flexible syntax and extensive reflexive metaprogramming facilities [3]. Reflexive metaprogramming is the capability of a program to both inspect

  4. ABSTRACT REFLEXIVE SUBLATTICES AND COMPLETELY DISTRIBUTIVE COLLAPSIBILITY

    E-print Network

    Nation, James B.

    ABSTRACT REFLEXIVE SUBLATTICES AND COMPLETELY DISTRIBUTIVE COLLAPSIBILITY W. E. Longstaff, J. B is completely distributive, then L is reflexive. In this paper we study the more general situation of complete. A subspace lattice L is reflexive if it is the set of invariant subspaces of some collection of operators

  5. Reflexive autoepistemic logic and logic programming

    E-print Network

    Marek, Victor W.

    Reflexive autoepistemic logic and logic programming V. Wiktor Marek Miroslaw Truszczy@ms.uky.edu Abstract In this paper we show that reflexive autoepistemic logic of Schwarz is a par- ticularly convenient of logic programs. Moreover, in the case of logic programs one can use reflexive autoepistemic logic which

  6. STRONG REFLEXIVITY OF ABELIAN GROUPS Montserrat Bruguera

    E-print Network

    Politècnica de Catalunya, Universitat

    STRONG REFLEXIVITY OF ABELIAN GROUPS Montserrat Bruguera Dept. de Matem'atica Aplicada I'atica Aplicada Universidad de Navarra e­mail: mjchasco@fisica.unav.es Abstract A reflexive topological group G is called strongly reflexive if each closed sub­ group and each Hausdorff quotient of the group G and of its

  7. REFLEXIVE DIGRAPHS WITH NEAR UNANIMITY POLYMORPHISMS

    E-print Network

    Maróti, Miklós

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

  8. Reflexivity of Isometries Wing-Suet Li *

    E-print Network

    McCarthy, John E.

    Reflexivity of Isometries Wing-Suet Li is reflexive. Let C be a set of bounded operators on a Hilbert space H, Lat(C) be the latt* *ice of all of polynomials: denote this set by W (C). If W (C) is all* * of AlgLat(C), then C is called reflexive

  9. Research report Elevated depressive symptoms enhance reflexive

    E-print Network

    Maddox, W. Todd

    Research report Elevated depressive symptoms enhance reflexive but not reflective auditory category system Reflexive system a b s t r a c t In vision an extensive literature supports the existence to develop and test rules for classifying in an explicit fashion. The reflexive system is striatally

  10. 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

  11. 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

  12. Vortex equation and reflexive sheaves

    E-print Network

    Indranil Biswas; Matthias Stemmler

    2011-11-28

    It is known that given a stable holomorphic pair $(E ,\\phi)$, where $E$ is a holomorphic vector bundle on a compact K\\"ahler manifold $X$ and $\\phi$ is a holomorphic section of $E$, the vector bundle $E$ admits a Hermitian metric solving the vortex equation. We generalize this to pairs $(\\E ,\\phi)$, where $\\E$ is a reflexive sheaf on $X$.

  13. 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

  14. Vestibular-ocular accommodation reflex in man

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

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

    PubMed

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

    1991-09-01

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

  16. 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.

  17. Development of the Stretch Reflex in the Newborn: Reciprocal Excitation and Reflex Irradiation.

    ERIC Educational Resources Information Center

    Myklebust, Barbara M.; Gottlieb, Gerald L.

    1993-01-01

    When tendon jerk reflexes were tested in seven newborns from one- to three-days old, stretch reflex responses in all major muscle groups of the lower limb were elicited. This "irradiation of reflexes" is a normal phenomenon in newborns, with the pathway becoming suppressed during normal maturation. In individuals with cerebral palsy, however, the…

  18. 9. Reflexive Objects and the TypeFree Lambda Calculus REFLEXIVE OBJECTS AND

    E-print Network

    Longo, Giuseppe

    9. Reflexive Objects and the Type­Free Lambda Calculus 204 Chapter 9 REFLEXIVE OBJECTS AND THE TYPE. Reflexive Objects and the Type­Free Lambda Calculus 205 toghether with the axioms and rules needed primitives for list manipulation. The main difference is in the binding strategy for variables, which

  19. 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

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

    PubMed

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

    2002-06-01

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

  1. AN UNCOUNTABLY INFINITE NUMBER OF INDECOMPOSABLE TOTALLY REFLEXIVE MODULES

    E-print Network

    Takahashi, Ryo

    AN UNCOUNTABLY INFINITE NUMBER OF INDECOMPOSABLE TOTALLY REFLEXIVE MODULES RYO TAKAHASHI Abstract- tain totally reflexive module implies the existence of an uncountably infinite number of isomorphism classes of indecomposable totally reflexive modules. 1. Introduction Throughout the present paper, we

  2. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Powered reflex hammer. 890.1450 Section 890.1450...Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device intended...

  3. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Powered reflex hammer. 890.1450 Section 890.1450...Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device intended...

  4. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Powered reflex hammer. 890.1450 Section 890.1450...Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device intended...

  5. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Powered reflex hammer. 890.1450 Section 890.1450...Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device intended...

  6. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Powered reflex hammer. 890.1450 Section 890.1450...Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device intended...

  7. 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.).

  8. Effects of stimulation of the insular cortex on execution of the antrofundal reflex in conscious dogs.

    PubMed

    Busygina, I I; Aleksandrov, V G; Lyubashina, O A; Panteleev, S S

    2010-05-01

    Neuroanatomical studies demonstrated the existence of direct descending projections from the insular cortex to the area of the solitary tract nucleus responsible for mediating the vagovagal reflexes of the proximal part of the gastrointestinal tract. These studies provided grounds for suggesting that one of the mechanisms mediating the influences of the insular cortex on stomach function may be modulation of its vagovagal reflex reactions, one of which is the antrofundal inhibitory reflex. Experiments on conscious dogs were performed to study the effects of electrical stimulation of the insular cortex on execution of the antrofundal gastric reflex in conditions of intermittent gastrointestinal tract activity during fasting. Stretching of the walls of the antral segment of the stomach during the active period of intermittent gastric activity led to suppression of contractions in the fundal segment. Electrical stimulation of the insular cortex was found to prolong this reflex reaction. Thus, one result of activation of the insular area of the cortex is enhancement of the inhibitory vagovagal gastric reflexes, in all probability occurring as a result of modulation of neurotransmission in the vagovagal reflex arc system. PMID:20339943

  9. 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

  10. 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

  11. 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…

  12. 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…

  13. 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

  14. Stable reflexive sheaves and localization

    E-print Network

    Gholampour, Amin

    2013-01-01

    We study moduli spaces $\\N$ of rank 2 stable reflexive sheaves on $\\PP^3$. Fixing Chern classes $c_1$, $c_2$, and summing over $c_3$, we consider the generating function $G^{refl}(q)$ of Euler characteristics of such moduli spaces. The action of the dense open torus $T$ on $\\PP^3$ lifts to $\\N$ and we classify all sheaves in $\\N^T$. This leads to an explicit expression for $G^{refl}(q)$. Since $c_3$ is bounded below and above, $G^{refl}(q)$ is a polynomial. For $c_1=-1$, we show its leading term is $12c_2 q^{c_{2}^{2}}$. Next, we study moduli spaces of rank 2 stable torsion free sheaves on $\\PP^3$ and consider the generating function $G(q)$ of Euler characteristics of such moduli spaces. We give an expression for this generating function in terms of $G^{refl}(q)$ and Euler characteristics of Quot schemes of certain $T$-equivariant reflexive sheaves. These Quot schemes and their fixed point loci are studied in a sequel with B. Young. The components of these fixed point loci are products of $\\PP^1$'s and give r...

  15. Autonomic reflexes in preterm infants.

    PubMed

    Lagercrantz, H; Edwards, D; Henderson-Smart, D; Hertzberg, T; Jeffery, H

    1990-01-01

    Some autonomic nervous reflexes often tested in adult medicine have been studied in 21 preterm infants (25-37 gestational weeks). The aim was to develop such tests for preterm infants and see if there were any differences in babies with recurrent apnea and bradycardia and babies who had been exposed to sympathicolytic drugs before birth. To test sympathetic nervous activity the peripheral vascular resistance was measured before and during 45 degrees of head-up tilting. To test parasympathetic nervous activity the degree of bradycardia was measured in response to cold face test (application of an ice-cube on the fore-head) and laryngeal stimulation with saline. Finally the heart rate changes after a sudden noise (85 dB) were studied as an indicator of both sympathetic and vagal activity. The peripheral resistance was found to be relatively low in these preterm infants, particularly in some infants tested at the postnatal age of about two months. Heart rate and mean blood pressure did not change during tilting, while the peripheral resistance increased significantly mainly due to lowered limb blood flow. The median decrease of the heart rate during the cold face test was 20.0% and during laryngeal receptor stimulation 23.7%. The sudden noise usually caused a biphasic heart rate response. An autonomic nervous reflex score was calculated and found to be negative (parasympathetic) in infants with recurrent prolonged apnea and bradycardia and positive in infants with clinical signs of increased sympathetic nervous activity. PMID:2239264

  16. [Complex profile of the reflex diving response].

    PubMed

    Wierzba, Tomasz H; Ropiak, Arkadiusz

    2011-01-01

    Breath-holding coupled with face cooling triggers a set of the reflex cardiovascular responses, defined as a diving reflex. The major reflex responses include a decrease in heart rate and peripheral vasoconstriction with an increase of arterial pressure to evoke central blood pooling with preferential provision of the brain and heart perfusion. Due to high individual variability and situational dependence the individual course of the reflex response is hardly predictable. Heart rhythm disturbances are the major, sometimes fatal complications of the response. This review is an outline of causing factors, circumstances, mechanisms and the effects of the diving reflex and their practical implications, including risk factors of the critical arrhythmias occurred in diving. PMID:22125213

  17. 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…

  18. Cortical modulation of transmission in spinal reflex pathways of man.

    PubMed Central

    Iles, J F; Pisini, J V

    1992-01-01

    1. The motor actions in the lower limb of transcranial electrical stimulation of the motor cortex have been studied in sitting human subjects. 2. Cortical stimulation induced a short latency inhibition of H reflexes evoked in soleus motoneurones both at rest and during small voluntary contractions of soleus. 3. Spatial interaction between cortical inhibition of soleus motoneurons and inhibition evoked through identified spinal reflex machinery was investigated. 4. Interactions were found between cortically evoked inhibition and spinal Ia reciprocal inhibition, group I non-reciprocal inhibition and higher threshold components of longer latency reciprocal inhibition (D1 and D2 inhibitions). 5. Interactions were facilitatory when cortical and spinal inhibitory actions were weak and reversed to occlusion when both actions were strong. 6. It is concluded that the corticospinal pathway converges on the interneurones which subserve Ia reciprocal, group I non-reciprocal, D1 and D2 inhibition of soleus motoneurones. 7. No significant interaction was found under the present experimental conditions between cortical stimulation and group Ia-Ia presynaptic inhibition of soleus afferents. 8. The statistical significance of spatial interactions observed with H reflex conditioning was investigated using a control experiment. PMID:1336554

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  20. Stable reflexive sheaves and localization

    E-print Network

    Amin Gholampour; Martijn Kool

    2015-09-14

    We study moduli spaces $\\mathcal{N}$ of rank 2 stable reflexive sheaves on $\\mathbb{P}^3$. Fixing Chern classes $c_1$, $c_2$, and summing over $c_3$, we consider the generating function $\\mathsf{Z}^{\\mathrm{refl}}(q)$ of Euler characteristics of such moduli spaces. The action of the dense open torus $T$ on $\\mathbb{P}^3$ lifts to $\\mathcal{N}$ and we classify all sheaves in $\\mathcal{N}^T$. This leads to an explicit expression for $\\mathsf{Z}^{\\mathrm{refl}}(q)$. Since $c_3$ is bounded below and above, $\\mathsf{Z}^{\\mathrm{refl}}(q)$ is a polynomial. For $c_1=-1$, we show its leading term is $12c_2 q^{c_{2}^{2}}$. Next, we study moduli spaces of rank 2 stable torsion free sheaves on $\\mathbb{P}^3$ and consider the generating function $\\mathsf{Z}(q)$ of Euler characteristics of such moduli spaces. We give an expression for this generating function in terms of $\\mathsf{Z}^{\\mathrm{refl}}(q)$ and Euler characteristics of Quot schemes of certain $T$-equivariant reflexive sheaves. These Quot schemes and their fixed point loci are studied in a sequel with B. Young. The components of these fixed point loci are products of $\\mathbb{P}^1$'s and give rise non-trivial combinatorics. For $c_1=-1$ and $c_2=1$, we obtain $\\mathsf{Z}(q) = 4(q+q^{-1}) M(q^{-2})^8$, where $M(q)$ is the MacMahon function. Many techniques of this paper apply to any toric 3-fold. In general, $\\mathsf{Z}^{\\mathrm{refl}}(q)$ depends on the choice of polarization which leads to wall-crossing phenomena. We briefly illustrate this in the case of $\\mathbb{P}^2 \\times \\mathbb{P}^1$.

  1. [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

  2. A CHARACTERIZATION OF SUBSPACES AND QUOTIENTS OF REFLEXIVE BANACH SPACES

    E-print Network

    Goldstein, Jerome A.

    A CHARACTERIZATION OF SUBSPACES AND QUOTIENTS OF REFLEXIVE BANACH SPACES WITH UNCONDITIONAL BASES W. B. JOHNSON and BENTUO ZHENG Abstract We prove that the dual or any quotient of a separable reflexive that a separable reflexive Banach space with the UTP embeds into a reflexive Banach space with an unconditional

  3. 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.

  4. Null Subjects are Reflexives, Not Pronouns Antonio Branco

    E-print Network

    Branco, António Horta

    Null Subjects are Reflexives, Not Pronouns Ant´onio Branco University of Lisbon Faculdade de Ci this empirical generalization and argues that null Subjects are reflexives rather than pronouns. The critical are reflexives in top-command positions, i.e. reflexives that have no immediate local commanders. The key issue

  5. REFLEXIVITY AND HYPERREFLEXIVITY OF THE SPACE OF LOCALLY INTERTWINING OPERATORS

    E-print Network

    Müller, Vladimír

    REFLEXIVITY AND HYPERREFLEXIVITY OF THE SPACE OF LOCALLY INTERTWINING OPERATORS J. BRA#I#, V) that are reflexive (hy­ perreflexive). We show that if e is not an eigenvector of A, then the reflexivity the reflexivity of the space of intertwiners I(A, B) and of the commutant of an operator. 1. Introduction

  6. On the Reflexivity of Point Sets Esther M. Arkin1

    E-print Network

    Fekete, Sándor P.

    On the Reflexivity of Point Sets Esther M. Arkin1 , S´andor P. Fekete2 , Ferran Hurtado3 , Joseph S distance from a convex set: The reflexivity (S) of S is given by the smallest number of reflex vertices to compute reflexivity, both exactly (in special cases) and approximately (in general). Our study naturally

  7. REFLEXIVITY AND HYPERREFLEXIVITY OF THE SPACE OF LOCALLY INTERTWINING OPERATORS

    E-print Network

    Müller, Vladimír

    REFLEXIVITY AND HYPERREFLEXIVITY OF THE SPACE OF LOCALLY INTERTWINING OPERATORS J. BRACIC, V) that are reflexive (hy- perreflexive). We show that if e is not an eigenvector of A, then the reflexivity the reflexivity of the space of intertwiners I(A, B) and of the commutant of an operator. 1. Introduction

  8. Tonic suppression of the soleus H-reflex during rhythmic movement of the contralateral ankle

    PubMed Central

    Mori, Nobuhiko; Horino, Hiroshi; Matsugi, Akiyoshi; Kamata, Noriyuki; Hiraoka, Koichi

    2015-01-01

    [Purpose] We investigated the effect of rhythmic ankle movement on the contralateral soleus H-reflex. The H-reflex was evoked from the right soleus muscle. [Subjects and Methods] Healthy humans rhythmically moved the left ankle (movement condition) or held the left ankle stationary (stationary condition) at one of three positions corresponding to the ankle positions at which the H-reflex was evoked in the movement condition. The background electromyographic amplitude in the right soleus muscle was maintained at 10% of the maximum voluntary contraction level, and that in the right tibialis anterior muscle was matched between the stationary and movement conditions. [Results] The soleus H-reflex was suppressed throughout all phases of contralateral rhythmic ankle movement. [Conclusion] Rhythmic movement of the contralateral joint suppresses the H-reflex in the muscle that is the prime mover of the joint homologous to the rhythmically moving joint. This inhibitory mechanism may be activated during unilateral rhythmic movement to isolate the motor control of the moving ankle from that of the contralateral stationary ankle. PMID:26157202

  9. Relationship of Postural Reflexes to Learning Disabilities

    ERIC Educational Resources Information Center

    Rider, Barbara A.

    1972-01-01

    The fact that the children with learning disorders had significantly more abnormal reflexes than did the normal children lends empirical support to the theory of minimal neurological impairment as a factor in the etiology of learning disabilities. (Author)

  10. Demonstrating the Stretch Reflex: A Mechanical Model.

    ERIC Educational Resources Information Center

    Batavia, Mitchell; McDonough, Andrew L.

    2000-01-01

    Explains the concept of stretch reflexes to students using a mechanical model. The model provides a dynamic multisensory experience using movement, light, and sound. Describes the construction design. (SAH)

  11. 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

  12. A testbed for autonomous reflexive grasping

    NASA Astrophysics Data System (ADS)

    Kemme, David A.; McDonnell, John R.

    1993-03-01

    This work describes the development of a testbed which combines a subsumption architecture approach with neural network processing of tactile information in a reflexive behavior feasibility study. An overview of the tactile sensor, the neural network processor, and subsumption architecture is provided along with a plan for integrating these components into a single system. By incorporating local (reflexive) processing capabilities within a robot gripper, an additional layer of control is attained without an increased computing burden being placed on the system controller.

  13. 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

  14. 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.

  15. Management of reflex anoxic seizures in children.

    PubMed

    Iyer, Anand; Appleton, Richard

    2013-09-01

    Reflex anoxic seizures (RAS) are important in the differential diagnosis of non-epileptic paroxysmal events in infants and preschool-aged children. They are classically provoked by a sudden distressing stimulus, which causes loss of consciousness followed by stiffening and brief clonic movements affecting some or all limbs, often misinterpreted as an epileptic seizure. The underlying pathophysiology is a vagal-induced brief cardiac asystole with resultant transient cerebral hypoperfusion. Parents and carers who witness the event are understandably anxious, and the mainstay of management are ensuring the appropriate timely diagnosis of RAS and excluding cardiac arrhythmia. A detailed history from a witness is all that is needed to diagnose this condition and investigations like EEG or neuroimaging should be avoided. Education and reassurance remain the mainstay in the management. Some children benefit from medical treatment with atropine or fluoxetine; however, there is a lack of evidence for pharmacological treatment. Cardiac pacing is the only definitive treatment, and is reserved for frequent, severe cases in joint consultation with the cardiologist. PMID:23814085

  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. 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.

  18. 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

  19. The trigeminocardiac reflex - a comparison with the diving reflex in humans.

    PubMed

    Lemaitre, Frederic; Chowdhury, Tumul; Schaller, Bernhard

    2015-04-25

    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. 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

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  2. 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

  3. 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

  4. Horizontal optokinetic reflex in the opossum Didelphis marsupialis aurita.

    PubMed

    Nasi, J P; Bernardes, R F; Volchan, E; Rocha-Miranda, C E; Tecles, M

    1989-01-01

    Electro-oculographic recordings were performed in 10 opossums. The optokinetic reflex was elicited by projecting a random dot stimulus on a cylindrical screen moving horizontally from left to right or right to left at various constant speeds. Binocular stimulation yielded the same response as the temporal to nasal monocular condition. The nasal to temporal monocular response was always less than that to the opposite direction: 50% at 3 degrees/s and 15% at 18 degrees/s. These results are discussed in a comparative context. PMID:2620191

  5. 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

  6. 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

  7. 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

  8. 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

  9. Spinal reflexes in the long-tailed stingray, Himantura fai.

    PubMed

    Kitchener, Peter D; Snow, Peter J

    2010-04-01

    We have exploited the segregation of motor and sensory axons into peripheral nerve sub-compartments to examine spinal reflex interactions in anaesthetized stingrays. Single, supra-maximal electrical stimuli delivered to segmental sensory nerves elicited compound action potentials in the motor nerves of the stimulated segment and in rostral and caudal segmental motor nerves. Compound action potentials elicited in segmental motor nerves by single stimuli delivered to sensory nerves were increased severalfold by prior stimulation of adjacent sensory nerves. This facilitation of the segmental reflex produced by intense conditioning stimuli decreased as it was applied to more remote segments, to approximately the same degree in up to seven segments in the rostral and caudal direction. In contrast, an asymmetric response was revealed when test and conditioning stimuli were delivered to different nerves, neither of which was of the same segment as the recorded motor nerve: in this configuration, conditioning volleys generally inhibited the responses of motoneurons to stimuli delivered to more caudally located sensory nerves. This suggests that circuitry subserving trans-segmental interactions between spinal afferents is present in stingrays and that interneuronal connections attenuate the influence that subsequent activity in caudal primary afferents can have on the motor elements. PMID:20213112

  10. Sudden infant death triggered by dive reflex.

    PubMed

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

    2005-01-01

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

  11. 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. 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

  13. Assignment A1: Reflex Agent -Assigned: 26 August 2014

    E-print Network

    Henderson, Thomas C.

    Assignment A1: Reflex Agent - Cleanup CS 5300 Fall 2014 Assigned: 26 August 2014 Due: 11 September) which studies statistics for a reflex agent cleaning robot. You should handin the report pdf as well

  14. Assignment A1: Reflex Agent -Assigned: 26 August 2014

    E-print Network

    Henderson, Thomas C.

    Assignment A1: Reflex Agent - Cleanup CS 6380 Fall 2014 Assigned: 26 August 2014 Due: 11 September) which studies statistics for a reflex agent cleaning robot. You should handin the report pdf as well

  15. Modulation of Stretch Reflexes of the Finger Flexors by Sensory Feedback From the Proximal Upper Limb Poststroke

    PubMed Central

    Hoffmann, Gilles; Kamper, Derek G.; Kahn, Jennifer H.; Rymer, William Z.; Schmit, Brian D.

    2009-01-01

    Neural coupling of proximal and distal upper limb segments may have functional implications in the recovery of hemiparesis after stroke. The goal of the present study was to investigate whether the stretch reflex response magnitude of spastic finger flexor muscles poststroke is influenced by sensory input from the shoulder and the elbow and whether reflex coupling of muscles throughout the upper limb is altered in spastic stroke survivors. Through imposed extension of the metacarpophalangeal (MCP) joints, stretch of the relaxed finger flexors of the four fingers was imposed in 10 relaxed stroke subjects under different conditions of proximal sensory input, namely static arm posture (3 different shoulder/elbow postures) and electrical stimulation (surface stimulation of biceps brachii or triceps brachii, or none). Fast (300°/s) imposed stretch elicited stretch reflex flexion torque at the MCP joints and reflex electromyographic (EMG) activity in flexor digitorum superficialis. Both measures were greatest in an arm posture of 90° of elbow flexion and neutral shoulder position. Biceps stimulation resulted in greater MCP stretch reflex flexion torque. Fast imposed stretch also elicited reflex EMG activity in nonstretched heteronymous upper limb muscles, both proximal and distal. These results suggest that in the spastic hemiparetic upper limb poststroke, sensorimotor coupling of proximal and distal upper limb segments is involved in both the increased stretch reflex response of the finger flexors and an increased reflex coupling of heteronymous muscles. Both phenomena may be mediated through changes poststroke in the spinal reflex circuits and/or in the descending influence of supraspinal pathways. PMID:19571191

  16. 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

  17. Impaired reflexive orienting to social cues in attention deficit hyperactivity disorder.

    PubMed

    Marotta, Andrea; Casagrande, Maria; Rosa, Caterina; Maccari, Lisa; Berloco, Bianca; Pasini, Augusto

    2014-08-01

    The present study investigated whether another person's social attention, specifically the direction of their eye gaze, and non-social directional cues triggered reflexive orienting in individuals with Attention Deficit Hyperactivity Disorder (ADHD) and age-matched controls. A choice reaction time and a detection tasks were used in which eye gaze, arrow and peripheral cues correctly (congruent) or incorrectly (incongruent) signalled target location. Independently of the type of the task, differences between groups were specific to the cue condition. Typically developing individuals shifted attention to the location cued by both social and non-social cues, whereas ADHD group showed evidence of reflexive orienting only to locations previously cued by non-social stimuli (arrow and peripheral cues) but failed to show such orienting effect in response to social eye gaze cues. The absence of reflexive orienting effect for eye gaze cues observed in the participants with ADHD may reflect an attentional impairment in responding to socially relevant information. PMID:24322656

  18. LongDistance Reflexives and the Binding Square of Opposition

    E-print Network

    Branco, António Horta

    1 Long­Distance Reflexives and the Binding Square of Opposition ANT�NIO BRANCO DFKI ­ German., Seoul, December 1996, the Long­Distance Reflexives Workshop, and the 4th International Conference­distance Reflexives and the Binding Square of Opposition uncovers a classical square of oppositions between the four

  19. Aerial Righting Reflexes in Flightless Animals Ardian Jusufi,1,

    E-print Network

    SYMPOSIUM Aerial Righting Reflexes in Flightless Animals Ardian Jusufi,1, * Yu Zeng,* Robert J and is ultimately necessary for a successful landing. Aerial righting reflexes have been described historically righting reflexes are widespread among arboreal vertebrates and arthropods and that they represent

  20. Dependency of Long-Distance Reflexives Institute of Continuing Education

    E-print Network

    Dependency of Long-Distance Reflexives Hyeran Lee Institute of Continuing Education Kyung Hee are not merged at the outset. 1 Introduction The locally bound reflexives have been explained by the traditional theory (Hornstein 2001). Questions are raised with regard to the reflexive forms that seem to be bound

  1. Control of volitional and reflexive saccades in Tourette's syndrome

    E-print Network

    Munoz, Douglas Perry

    Control of volitional and reflexive saccades in Tourette's syndrome Adrienne L. LeVasseur1, J the execution and/or suppression of reflexive and/or voluntary saccades. In the immediate saccade tasks.e. reflexive pro-saccades on anti-saccade trials) was normal in the immediate anti-saccade task, suggesting

  2. LEXICAL INFORMATION AND PRAGMATIC INFORMATION: REFLEXIVITY OF AN EVENT AND

    E-print Network

    LEXICAL INFORMATION AND PRAGMATIC INFORMATION: REFLEXIVITY OF AN EVENT AND RESULTATIVE This paper examines the interaction of semantic factors of reflexivity in the availability of result type te-ir and te-ar constructions in Japanese. The semantic factors of reflexivity have been examined in a number

  3. UNIFORM EMBEDDINGS OF BOUNDED GEOMETRY SPACES INTO REFLEXIVE BANACH SPACE

    E-print Network

    Guentner, Erik

    UNIFORM EMBEDDINGS OF BOUNDED GEOMETRY SPACES INTO REFLEXIVE BANACH SPACE sequence of expanding graphs uniformly embeds into such a reflexive Banach space even though(N). The Banach space in the statement is reflexive. Thus, every bounded geometry metric space can be uniformly

  4. PULL-BACK MORPHISMS FOR REFLEXIVE DIFFERENTIAL FORMS STEFAN KEBEKUS

    E-print Network

    Kebekus, Stefan

    PULL-BACK MORPHISMS FOR REFLEXIVE DIFFERENTIAL FORMS STEFAN KEBEKUS ABSTRACT. Let f : X Y on rationally chain connected spaces 15 Part II. Pull-back properties of reflexive differentials on klt spaces¨ahler differentials rather hard to work with in many cases of practical interest. Reflexive differentials: Given

  5. Improved Upper Bounds on the Reflexivity of Eyal Ackerman

    E-print Network

    Improved Upper Bounds on the Reflexivity of Point Sets Eyal Ackerman Oswin Aichholzer Bal´azs Keszegh November 8, 2007 Abstract Given a set S of n points in the plane, the reflexivity of S, (S), is the minimum number of reflex vertices in a simple polygonalization of S. Arkin et al. [4] proved that (S) n/2

  6. FACHBEREICH 3 ON THE REFLEXIVITY OF POINT SETS

    E-print Network

    Hurtado, Ferran

    FACHBEREICH 3 MATHEMATIK ON THE REFLEXIVITY OF POINT SETS by ESTHER M. ARKIN S â?? ANDOR P. FEKETE; On the Reflexivity of Point Sets Esther M. Arkin #3; Sâ??andor P. Fekete y Ferran Hurtado z Joseph S. B. Mitchell #3 S. Intuitively, it describes the combinatorial distance from a convex set: The reflexivity #26;(S

  7. The startle reflex in schizophrenia: habituation and personality correlates

    E-print Network

    The startle reflex in schizophrenia: habituation and personality correlates Sare J. Akdaga,b , Paul, the startle reflex represents an alternative method for studying reactivity and habituation in schizophrenia of activation, the startle reflex is consid- ered a measure of reactivity to environmental stimuli

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

    ERIC Educational Resources Information Center

    Blasco, Maribel

    2012-01-01

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

  9. On the Reflexivity of Point Sets Esther M. Arkin

    E-print Network

    Sethia, Saurabh

    On the Reflexivity of Point Sets Esther M. Arkin S´andor P. Fekete Ferran Hurtado Joseph S. B S that captures a combina- torial distance that S is from being a convex set: The reflexivity (S) of S is given by the smallest number of reflex vertices in a simple polygonalization of S. We prove combinatorial bounds

  10. On orbit-reflexive operators V. Muller, J. Vrsovsky

    E-print Network

    Müller, Vladimír

    On orbit-reflexive operators V. M¨uller, J. Vrsovsk´y Abstract. Let T be a bounded linear Banach space operator such that n=1 1 T n reflexive. In particular, every Banach space operator with spectral radius different from 1 is orbit-reflexive. Better estimates are obtained

  11. Reflex Magnetics Cryptographic Library v.1.0

    E-print Network

    Reflex Magnetics Cryptographic Library v.1.0 Security Policy FIPS 140-2 Level 1 Version 1.44 15th May 2007 #12;Reflex Magnetics Cryptographic Library v.1.0 Security Policy Page 2 ©2006-2007 Check purposes about the structure of the Reflex Magnetics Cryptographic Library as it pertains to FIPS 140

  12. REFLEXIVITY OF SUBNORMAL OPERATORS John E. McCarthy

    E-print Network

    McCarthy, John E.

    REFLEXIVITY OF SUBNORMAL OPERATORS John E. Mc a new proof that subnormal operators are reflexive. We e* *xtend this to certain subnormal n-tuples. We give the first complete proof that a pair o* *f doubly commuting isometries is reflexive

  13. Diminished Pupillary Light Reflex at High Irradiances in

    E-print Network

    Diminished Pupillary Light Reflex at High Irradiances in Melanopsin-Knockout Mice R. J. Lucas,1 * S, and project to brain nuclei involved in non­image-forming visual functions such as pupillary light reflex, morphology, and projections were unchanged. These animals showed a pupillary light reflex indistinguishable

  14. Computing vertex-surjective homomorphisms to partially reflexive trees

    E-print Network

    Paulusma, Daniel

    Computing vertex-surjective homomorphisms to partially reflexive trees Petr A. Golovach1 , Dani partially reflexive tree. Thus we identify the first class of target graphs H for which the computational and call them reflexive, whereas vertices with no self-loop are said to be irreflexive. A graph

  15. STABLE MODELS AND REFLEXIVE BANACH SPACES JOSE IOVINO

    E-print Network

    Iovino, José - Iovino, José

    STABLE MODELS AND REFLEXIVE BANACH SPACES JOS´E IOVINO ABSTRACT. We show that a formula (x, y) is stable if and only if is the pairing map on the unit ball of E � E, where E is a reflexive Banach space. A similar distinction exists in Banach space geometry between reflexive and nonre- flexive spaces. A Banach

  16. REFLEXIVITY AND HYPERREFLEXIVITY OF THE SPACE OF LOCALLY INTERTWINING OPERATORS

    E-print Network

    Müller, Vladimír

    REFLEXIVITY AND HYPERREFLEXIVITY OF THE SPACE OF LOCALLY characterize the spaces of all local intertwiners I(A, B; e* *) that are reflexive (hy- perreflexive the reflexivity of the space of intertwiners I(A, B) and of the commutan* *t of an operator

  17. ON THE NUMBER OF INDECOMPOSABLE TOTALLY REFLEXIVE MODULES

    E-print Network

    Takahashi, Ryo

    ON THE NUMBER OF INDECOMPOSABLE TOTALLY REFLEXIVE MODULES RYO TAKAHASHI Abstract. In this note isomorphism classes of indecomposable totally reflexive modules, if there is a nonfree cyclic totally reflexive module. 1. Introduction Throughout this note, we assume that all rings are commutative

  18. Ambiguity of Reflexives and Case Extension* Richard Zuber

    E-print Network

    Ambiguity of Reflexives and Case Extension* Richard Zuber CNRS, Paris, France Richard.Zuber@linguist.jussieu.fr Abstract. It is suggested that the difference between co-referential and bound reflexive pronouns found nominal case extension first. Bound reflexives are reflexivisers in the sense that they are not case

  19. Reflexivity of Isometries WingSuet Li \\Lambda

    E-print Network

    McCarthy, John E.

    Reflexivity of Isometries Wing­Suet Li \\Lambda John E. M c Carthy y Georgia Institute of Technology Abstract We prove that any set of commuting isometries on a separable Hilbert space is reflexive. Let C) is all of AlgLat(C), then C is called reflexive. In this note we prove that any set of commuting

  20. REFLEXIVITY OF SUBNORMAL OPERATORS John E. M c Carthy

    E-print Network

    McCarthy, John E.

    REFLEXIVITY OF SUBNORMAL OPERATORS John E. M c Carthy Dedicated to Donald Sarason, in admiration of the range of his pioneering work Abstract. We give a new proof that subnormal operators are reflexive. We commuting isometries is reflexive. 0. Introduction Let A be a weakly closed algebra of bounded linear

  1. Splitting criterion for reflexive sheaves TAKURO ABE MASAHIKO YOSHINAGA

    E-print Network

    Splitting criterion for reflexive sheaves TAKURO ABE MASAHIKO YOSHINAGA April 6, 2005 Abstract The purpose of this paper is to study the structure of reflexive sheaves over projective spaces through hyperplane sections. We give a criterion for a reflexive sheaf to split into a direct sum of line bundles

  2. 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…

  3. Effects of perceptual load on startle reflex modification at a long lead interval

    E-print Network

    Effects of perceptual load on startle reflex modification at a long lead interval GARY L. THORNE Abstract Inhibition of the startle eyeblink response at long lead intervals has been hypothesized to occur the lead and startle stimuli are in different modalities under conditions of high perceptual load

  4. 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)

  5. Monosynaptic reflexes in the superficial forearm flexors in man and their clinical significance.

    PubMed

    Deschuytere, J; Rosselle, N; De Keyser, C

    1976-06-01

    Indirect motor responses with the characteristics of the H wave were recorded from the flexor carpi radialis and the palmaris longus muscles in normal adults. A series of experiments has been performed, constituting circumstantial arguments for the monosynaptic nature of these reflex responses. The findings in pathological conditions, which corroborated this point of view, are documented briefly. PMID:181537

  6. Monosynaptic reflexes in the superficial forearm flexors in man and their clinical significance.

    PubMed Central

    Deschuytere, J; Rosselle, N; De Keyser, C

    1976-01-01

    Indirect motor responses with the characteristics of the H wave were recorded from the flexor carpi radialis and the palmaris longus muscles in normal adults. A series of experiments has been performed, constituting circumstantial arguments for the monosynaptic nature of these reflex responses. The findings in pathological conditions, which corroborated this point of view, are documented briefly. Images PMID:181537

  7. The photomyoclonic reflex: an artefact in the clinical electroretinogram.

    PubMed Central

    Johnson, M A; Massof, R W

    1982-01-01

    An artefact may appear in the clinical electroretinogram (ERG) that can interfere with the recording and interpretation of the ERG b wave. This artefact, the photomyoclonic reflex (PMR), was studied by covering the eye containing the recording electrode and stimulating the fellow eye. Records obtained by this technique before and after administration of a modified Van Lint lid block demonstrated that most of the PMR is due to a reflex contraction of the orbicularis muscle. The remaining part of the PMR was ascertained by eye movement recordings to be a 1.5 degrees to 3.5 degrees downward and medial eye movement. In most persons the PMR occurs with a latency that is fast enough (59 ms +2- 7 ms) to interfere with interpretation of the b wave under most conditions. The PMR can be minimised in some cases by habituation or conditioned suppression. However, these methods generally do not extinguish the PMR but reduce it enough so that it would not readily be rejected as artefact. In such cases the PMR may produce a wave form that mimics a normal amplitude ERG but with delayed implicit time. Images PMID:7082606

  8. 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…

  9. Emotion, Attention, and the Startle Reflex.

    ERIC Educational Resources Information Center

    Lang, Peter J.; And Others

    1990-01-01

    Evidence that the vigor of the startle reflex varies systematically with the organism's emotional state is reviewed. A theory elucidating this relationship suggests how amplitude of eyeblink response to a probe may be modulated by affective content of perception and thought. Implications for research on emotion are outlined. (SLD)

  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. 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.

  12. 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…

  13. 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

  14. 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…

  15. Conditionals

    E-print Network

    von Fintel, Kai

    2011-01-01

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

  16. Serotonin transporter and reflexive/reflective processing 1 Serotonin transporter genetic variation is differentially associated with reflexive-and reflective-

    E-print Network

    Maddox, W. Todd

    Serotonin transporter and reflexive/reflective processing 1 Serotonin transporter genetic variation is differentially associated with reflexive- and reflective- optimal learning W. Todd Maddoxa Marissa A. Gorlickb) on participants' ability to engage the task appropriate cognitive system when the reflexive (Experiments 1 and 2

  17. [Reflex effects of cough reflex on the tracheobronchial vascular tone (author's transl)].

    PubMed

    Yanaura, S; Hosokawa, T; Kitagawa, H; Misawa, M

    1981-07-01

    In a previous paper, it was shown that the cough reflex was accompanied by a slight fall of systemic arterial pressure, tracheal constriction and tracheal vasodilation. In the present study, tracheobronchial muscular and vascular tones during the cough reflex were investigated using the blood perfused canine tracheal and bronchial preparations in situ. The cough reflex was elicited with electrical stimulation of the membraneous wall mucosa of the upper trachea. In the blood perfused tracheal preparation, a close intraarterial injection of atropine or bilateral vagotomy inhibited the tracheoconstriction but had no effect on the tracheal vasodilation during the cough reflex. In the blood perfused bronchial preparation, electrical stimulation of the upper tracheal mucosa induced bronchial constriction but not bronchial vasodilation. Lung inflation with air resulted in a bronchial vasodilation and which persisted even after a close intraarterial infusion of atropine and benzonatate and after bilateral vagotomy. These findings indicate that the tracheobronchial constriction response are primary reflex effects following coughing and the tracheobronchial vasodilation responses are secondary reflex effects induced by increase in internal pressure of the respiratory tract. PMID:7308898

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Soleus H-reflex excitability changes in response to sinusoidal hip stretches in the injured human spinal cord.

    PubMed

    Knikou, Maria; Schmit, Brian D; Chaudhuri, Debjani; Kay, Elizabeth; Rymer, William Zev

    2007-08-01

    Imposed static hip stretches substantially modulate the soleus H-reflex in people with an intact or injured spinal cord while stretch of the hip flexors affect the walking pattern in lower vertebrates and humans. The aim of this study was to assess the effects of dynamic hip stretches on the soleus H-reflex in supine spinal cord injured (SCI) subjects. Sinusoidal movements were imposed on the right hip joint at 0.2 Hz by a Biodex system. H-reflexes from the soleus muscle were recorded as the leg moved in flexion or extension. Stimuli were sent only once in every hip movement cycle that each lasted 5 s. Torque responses were recorded at the hip, knee, and ankle joints. A hip phase-dependent soleus H-reflex modulation was present in all subjects. The reflex was facilitated during hip extension and suppressed during hip flexion. There were no significant differences in pre- or post-stimulus soleus background activity between the two conditions. Oscillatory responses were present as the hip was maximally flexed. Sinusoidal hip stretches modulated the soleus H-reflex in a manner similar to that previously observed following static hip stretches. The amount of reflex facilitation depended on the angle of hip extension. Further research is needed on the afferent control of spinal reflex pathways in health and disease in order to better understand the neural control of movement in humans. This will aid in the development of rehabilitation strategies to restore motor function in these patients. PMID:17658691

  4. Neural mechanisms of soleus H-reflex depression accompanying voluntary arm movement in standing humans.

    PubMed

    Kawanishi, M; Yahagi, S; Kasai, T

    1999-06-19

    This study have investigated the changes in soleus (Sol) H-reflexes by arm movement during freely standing (FS) and back-supported standing (BS) in healthy subjects. Before the arm movement, there is an anticipatory phase, which includes increased electromyographic (EMG) activity in the biceps femoris (BF) and decreased EMG activity of the Sol muscle. The Sol H-reflex appeared to be inhibited during the anticipatory phase as well as during the time of arm movement. However, the inhibition appeared to be larger in FS than in BS conditions. Vibration applied to the tendon of the BF muscle depressed the Sol H-reflex. This inhibition was attributed to presynaptic inhibition and was reduced during the anticipatory phase, and was not very much changed during arm movements. It is suggested that the depression of the Sol H-reflex induced by voluntary arm movement has two inhibitory components of different origins. Descending motor commands generate the early inhibitory component, while the late component is produced by the presynaptic inhibition that results from peripheral inputs. The inhibition related to anticipatory postural adjustment (APA) indicates that a new-setting of the spinal mechanisms is required and responsible in order to stabilize body equilibrium which is dependent upon different postural conditions. PMID:10375647

  5. 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

  6. 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.

  7. How to Classify Reflexive Gorenstein Cones

    E-print Network

    Harald Skarke

    2012-04-05

    Two of my collaborations with Max Kreuzer involved classification problems related to string vacua. In 1992 we found all 10,839 classes of polynomials that lead to Landau-Ginzburg models with c=9 (Klemm and Schimmrigk also did this); 7,555 of them are related to Calabi-Yau hypersurfaces. Later we found all 473,800,776 reflexive polytopes in four dimensions; these give rise to Calabi-Yau hypersurfaces in toric varieties. The missing piece - toric constructions that need not be hypersurfaces - are the reflexive Gorenstein cones introduced by Batyrev and Borisov. I explain what they are, how they define the data for Witten's gauged linear sigma model, and how one can modify our classification ideas to apply to them. I also present results on the first and possibly most interesting step, the classification of certain basic weights systems, and discuss limitations to a complete classification.

  8. How to classify reflexive Gorenstein cones

    NASA Astrophysics Data System (ADS)

    Skarke, Harald

    2013-10-01

    Two of my collaborations with Max Kreuzer involved classification problems related to string vacua. In 1992 we found all 10,839 classes of polynomials that lead to Landau-Ginzburg models with c=9 (Klemm and Schimmrigk also did this); 7,555 of them are related to Calabi-Yau hypersurfaces. Later we found all 473,800,776 reflexive polytopes in four dimensions; these give rise to Calabi-Yau hypersurfaces in toric varieties. The missing piece -- toric constructions that need not be hypersurfaces -- are the reflexive Gorenstein cones introduced by Batyrev and Borisov. I explain what they are, how they define the data for Witten's gauged linear sigma model, and how one can modify our classification ideas to apply to them. I also present results on the first and possibly most interesting step, the classification of certain basic weights systems, and discuss limitations to a complete classification.

  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. A bladder-to-bladder cooling reflex in the cat.

    PubMed Central

    Fall, M; Lindström, S; Mazières, L

    1990-01-01

    1. Reflex effects of cold stimulation of the lower urinary tract were studied in cats anaesthetized with alpha-chloralose. The bladder and the urethra were catheterized for separate fluid instillations and the bladder pressure was monitored together with the evoked efferent nerve responses in pelvic nerve filaments. 2. A bladder cooling reflex could be evoked from both the bladder and the urethra. The response was an efferent discharge in preganglionic pelvic motor fibres to the bladder. 3. Bladder mechanoreceptors that drive the normal micturition reflex were not directly involved in the cooling reflex. Their tension sensitivity was decreased by cooling and the efferent reflex response typically occurred before any activation of these receptors. The efferent activity of the cooling reflex also survived an intentional unloading of the mechanoreceptors, a manipulation that abolishes the normal micturition reflex. 4. The dynamic threshold temperature of the cooling reflex was about 30-32 degrees C, which was at the thermal neutral point of the bladder in our experimental situation. 5. The bladder-evoked component of the reflex was greatly reduced or abolished by an intravesical infusion of the local anaesthetic Xylocaine. It was also abolished by total bladder denervation. 6. The vesical component of the reflex was unchanged by bilateral transections of the hypogastric nerves but abolished by pelvic nerve transection. The cooling reflex from the distal urethra was abolished by transection of the pudendal nerves. 7. It was proposed that the cooling reflex originates from cold receptors in the bladder and urethral walls and that the responsible afferent fibres are unmyelinated C fibres. The function of the reflex may be to rid the body of a thermal ballast when under cooling stress. PMID:2213600

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. http://www.tutis.ca/NeuroMD/index.htm 19 February 2013 Muscle Receptors, Spinal Reflexes and

    E-print Network

    Vilis, Tutis

    0 http://www.tutis.ca/NeuroMD/index.htm 19 February 2013 Muscle Receptors, Spinal Reflexes Reflexes and Muscles ............................................................... 0 Contents Three spinal reflexes

  16. 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

  17. [Stabilization of the gaze in chameleons: visual and vestibular reflexes].

    PubMed

    Bennis, M; Sansonetti, A; Gioanni, H

    1990-01-01

    Some visual, vestibular and proprioceptive reflexes which contribute to gaze (head + eye) stabilization were quantified in the chameleon. All the reflexes were analysed in the horizontal plane, and the visual reflexes were also studied in the vertical plane. In restrained-head animals, both the optokinetic nystagmus (OKN) and the vestibulo-ocular reflex (VOR) had low gains. In free-head animals, the head (opto-collic or vestibulo-collic reflex) and eye (OKN or VOR) responses added their effects, thus improving gaze stabilization, especially during vestibular stimulation. Cervical stimulation provoked both a cervico-ocular reflex (COR) in the compensatory direction and a large number of saccades. The saccadic response was especially marked in the presence of patterned visual surroundings. PMID:2125847

  18. 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

  19. On-line, Reflexive Constraint Satisfaction for Hybrid Systems: First Steps

    E-print Network

    Branicky, Michael S.

    On-line, Reflexive Constraint Satisfaction for Hybrid Systems: First Steps (Invited Presentation of functionality, (1) piece-wise viable servo controllers and (2) a "reflex con- troller," are required is called reflex con- trol. Reflex control (or reflexes) obtains its name from the analogy to animal

  20. Behavioral/Systems/Cognitive Specificity of Reflex Adaptation for Task-Relevant

    E-print Network

    Franklin, David

    Behavioral/Systems/Cognitive Specificity of Reflex Adaptation for Task-Relevant Variability David W with reflexes, such as the vestibulo-ocular reflex or stretch reflex, whose gains adapt in response to novel we demonstrate a reflex response to shifts in the hand's visual location during reaching, which

  1. Attention to bright surfaces enhances the pupillary light reflex.

    PubMed

    Binda, Paola; Pereverzeva, Maria; Murray, Scott O

    2013-01-30

    One longstanding question is how early in the visual system attention exerts its influence. Here we show that an effect of attention can be measured at the earliest possible stage of visual information processing, as a change in the optics of the eye. We tested human subjects and found that covertly attending to bright surfaces results in an enhanced pupillary light reflex (PLR)-the pupillary constriction that occurs in response to light increments. The PLR optimizes the optical quality of the retinal image across illumination conditions, increasing sensitivity by modulating retinal illumination, and improving acuity by reducing spherical aberrations. The attentional modulation of the PLR that we describe constitutes a new mechanism through which vision is affected by attention; we discuss three alternatives for the neural substrates of this effect, including the possibility that attention might act indirectly, via its well established effects in early visual cortex. PMID:23365255

  2. 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.

  3. Dopamine agonists suppress visual-cortical reflex myoclonus.

    PubMed

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

    1985-12-01

    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. PMID:3936901

  4. 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.

  5. Do cutaneous receptors contribute to the changes in the amplitude of the H-reflex during massage?

    PubMed

    Morelli, M; Chapman, C E; Sullivan, S J

    1999-01-01

    Massage is known to produce a reduction in spinal reflex excitability. However, the mechanisms subserving this phenomenon have yet to be elucidated. This study was undertaken to determine the role of superficial cutaneoreceptors overlying the triceps surae during the application of a massage. Twelve neurologically healthy volunteers were subjected to an interrupted repeated measures design consisting of eight conditions. Each condition was comprised of eleven H-reflex recordings obtained from the right soleus muscle. Six conditions served to establish baseline control levels, while the remaining two conditions consisted of reflex recordings obtained simultaneous to the application of the massage. During the first massage condition, subjects were at rest while a three minute petrissage was applied to the right triceps surae muscle group. The second massage condition was always preceded by the application of a topical anaesthetic to abolish the sensation to touch and pin-prick to the skin area that was to be massaged. It was expected that the cutaneous afferents would not play any major role in the changes associated with the application of the massage. H-reflex amplitudes recorded during each massage condition (1.20 mV +/- 0.30 SEM, 1.05 mV +/- 0.23 SEM, respectively) were significantly reduced (F7.77 = 26.048, p < 0.01) in contrast to all control conditions (range: 2.21 to 2.63 mV). However, no difference was observed between the two massage conditions. The inhibitory effects of massage on the soleus H-reflex do not appear to originate from mechanical stimulation of cutaneous mechanoreceptors. It seems more likely that deep mechanoreceptors are involved. PMID:10546081

  6. Eric Penain rejoint Reflex CES comme Directeur des ventes Reflex CES, (Custom Embedded Systems) fournisseur de systmes embarqus complexes cl en main, annonce

    E-print Network

    Baudoin, Geneviève

    Eric Penain rejoint Reflex CES comme Directeur des ventes Reflex CES, (Custom Embedded Systems Reflex CES en France et à l'international. Eric, 44 ans, cumule plus de 20 ans d'expérience dans l sein de Reflex CES un directeur des ventes de la notoriété d'Eric », déclare Sylvain Neveu, co

  7. An Enabling Framework for Reflexive Learning: Experiential Learning and Reflexivity in Contemporary Modernity

    ERIC Educational Resources Information Center

    Dyke, Martin

    2009-01-01

    The paper presents an enabling framework for experiential learning that connects with reflexive modernity. This framework places an emphasis on learning with others and on the role of theory, practice and reflection. A sociological argument is constructed for an alternative framework for experiential learning that derives from social theory. It is…

  8. Methodological Reflexivity: Towards Evolving Methodological Frameworks through Critical and Reflexive Deliberations

    ERIC Educational Resources Information Center

    Raven, Glenda

    2006-01-01

    In this article, the author argues for a central and critical role for "reflexivity in research" with the aim of developing and strengthening not only everyone's understanding of what everyone does in environmental education research, but also how, and why everyone does it. In a narrative account of methodological issues that occurred within, and…

  9. Recovery of the Vestibulocolic Reflex After Aminoglycoside Ototoxicity in Domestic Chickens

    E-print Network

    Rubel, Edwin

    Recovery of the Vestibulocolic Reflex After Aminoglycoside Ototoxicity in Domestic Chickens. Recovery of the vestibulocolic reflex after amino- glycoside ototoxicity in domestic chickens. J normally. In an earlier study we showed that the vestibuloocular reflex (VOR) is eliminated

  10. The Effects of Stress on Reflexive Processing Vaibhav Sapuram, Marissa Gorlick, & W. Todd Maddox

    E-print Network

    Maddox, W. Todd

    The Effects of Stress on Reflexive Processing Vaibhav Sapuram, Marissa Gorlick, & W. Todd Maddox Department of Psychology, University of Texas at Austin Reflexive vs. Reflective Processing · When presented with repetitive, predictable outcomes, reflexive processing assists in generating automatic behaviors requiring

  11. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... false Retroreflective sheeting and reflex reflectors, requirements for semitrailers...393.13 Retroreflective sheeting and reflex reflectors, requirements for semitrailers...retroreflective sheeting or an array of reflex reflectors that meet the...

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... false Retroreflective sheeting and reflex reflectors, requirements for semitrailers...393.13 Retroreflective sheeting and reflex reflectors, requirements for semitrailers...retroreflective sheeting or an array of reflex reflectors that meet the...

  13. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... false Retroreflective sheeting and reflex reflectors, requirements for semitrailers...393.13 Retroreflective sheeting and reflex reflectors, requirements for semitrailers...retroreflective sheeting or an array of reflex reflectors that meet the...

  14. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... false Retroreflective sheeting and reflex reflectors, requirements for semitrailers...393.13 Retroreflective sheeting and reflex reflectors, requirements for semitrailers...retroreflective sheeting or an array of reflex reflectors that meet the...

  15. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... false Retroreflective sheeting and reflex reflectors, requirements for semitrailers...393.13 Retroreflective sheeting and reflex reflectors, requirements for semitrailers...retroreflective sheeting or an array of reflex reflectors that meet the...

  16. 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.

  17. 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

  18. Startle reflex modulation and autonomic responding during anxious apprehension in panic disorder patients.

    PubMed

    Melzig, Christiane A; Weike, Almut I; Zimmermann, Jörg; Hamm, Alfons O

    2007-11-01

    The present study explored anxious apprehension in panic disorder patients and controls in two threat conditions, darkness and threat of shock. Autonomic arousal and startle eyeblink reflexes were recorded in 26 panic disorder patients and 22 controls during adaptation, a safe condition, threat of shock, and darkness. Exposure to darkness resulted in a clear potentiation of the startle reflex. Panic patients but not controls responded with an increase in heart rate that was positively related to severity of agoraphobic avoidance. Threat of shock resulted in a startle potentiation that tended to be stronger in panic patients without comorbid depression than controls and attenuated in those patients who suffered from severe depression. These data suggest that only panic patients without depression belong to the fear disorders spectrum whereas panic patients with comorbid depression might rather belong to the distress disorders profile. PMID:17640268

  19. 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

  20. 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

  1. 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

  2. Avoiding Reflex Responses: Strategies for Revealing Students' Conceptual Understanding in Biology

    E-print Network

    Klymkowsky, Mike

    Avoiding Reflex Responses: Strategies for Revealing Students' Conceptual Understanding in Biology and strategies we use to create questions that better probe student understanding. Keywords: reflexive responses

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

    E-print Network

    Johnson, William B.

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

  4. 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…

  5. Reflexivity of Discomfort in Insider-Outsider Educational Research

    ERIC Educational Resources Information Center

    Hamdan, Amani K.

    2009-01-01

    This paper discusses my position as an Arab Muslim woman researcher who is affiliated with a Western university, researching Arab Muslim Canadian women. I discuss how reflexivity has emerged as an element of my research endeavours. Various notions of reflexivity in educational research have been expressed in the literature, yet I focus on what it…

  6. 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...

  7. Enteropancreatic reflexes mediating the pancreatic enzyme response to nutrients.

    PubMed

    Niebergall-Roth, Elke; Singer, Manfred V

    2006-04-30

    The observation that in dogs electrical stimulation of the vagus nerve elicited a strong secretory activity of the pancreas, prompted I. P. Pavlov in 1888 to conclude that the pancreatic secretory response to nutrients is mediated by enteropancreatic reflexes involving the vagus nerves. It took, however, more than 90 years until by studying the latency of pancreatic amylase response to exogenous and endogenous stimuli for the first time experimental evidence was provided for the actual existence of cholinergic vago-vagal enteropancreatic reflexes. Follow-up studies, based on stepwise extrinsic denervation of the pancreas, ruled out possible splanchnic pathways for enteropancreatic reflexes. In more recent years, experiments utilizing specific antagonists demonstrated a physiological role for both cholinergic M1 and cholecystokinin (CCK) receptors within the enteropancreatic reflex. At least a significant portion of the cholinergic fibres of the enteropancreatic reflex end on muscarinic receptors of the subtype M1. CCK, the most important hormone stimulating pancreatic enzyme secretion, appears to act at least in part on CCK receptors located on vagal afferent nerves, which in turn elicit a vago-vagal reflex, implying that CCK exerts its effect on the pancreas at least in part through vago-vagal reflexes. Furthermore, pharmacological blockade of CCK receptors totally abolished the early pancreatic amylase response to intestinal nutrients, suggesting that the activation of (probably vagal) CCK receptors is essential to run the enteropancreatic reflex. PMID:16490403

  8. Reflex chemoceptive excitation of diencephalic sham rage behavior'

    E-print Network

    Bizzi, Emilio

    Reflex chemoceptive excitation of diencephalic sham rage behavior' E. BI,ZZI, A. LIBRETTI, A. LIBRETTI, A. MALLIANI, AND A. ZANCHETTI. Reflex chemoceptive excitation of diencephalic sham rage behavior of the carotid body chemoceptors was constantly capable of evoking sham rage outbursts identical in pattern

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. Comparison of the postural and movement components during learning by dogs of an operant defensive reflex.

    PubMed

    Shapovalova, K B; Chikhman, V N

    2003-09-01

    Chronic experiments on six dogs using a model of an operant defensive reflex associated with maintenance of flexion of the hindlimb of specified amplitude were performed to compare the characteristics of the postural and movement components during the learning process. Dogs were placed standing on four tension platforms. Signals were activated and data were recorded and stored using original PC programs. Original programs running on another PC were used to analyze the data. All dogs showed a series of characteristics for the appearance of a diagonal pattern of conditioned reflex posture rearrangement. During the period of complete formation of the "coordinated" program of the operant reflex (indicated by high performance criteria for execution of the operant task), the diagonal pattern of posture rearrangement was seen extremely rarely, in only occasional performances in calm dogs. It was only during the period of complete automatization of the movement habit that the diagonal pattern of postural rearrangement was seen consistently in all performances. By this time, there was a sharp increase in the tensogram amplitudes for all four limbs, which sharp increases in the correlation coefficients between individual tensogram performances. These results suggest that in the experimental conditions used here, the diagonal pattern of postural rearrangement appeared significantly later than the movement pattern needed for resolving the operant task. These data also lead to the conclusion that dogs can complete operant defensive limb movements associated with maintaining a specified flexor posture in the absence of preliminary rearrangement of the posture having the diagonal pattern. PMID:14552536

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Why Unergatives Select Themselves a Fake Reflexive

    E-print Network

    Grove, Kyle Wade

    2008-01-01

    [1995]. (4) a. The soldiers marched to the tents. LRH [p.111] b. The general marched the soldiers to the tents. LRH [p.111] (5) a. The horse jumped over the fence. LRH [p.111] b. The rider jumped the horse over the fence. LRH [p.111] (6) a. The mouse ran...-Davidsonian analysis of secondary predicative fake reflexives. (29) a. The Flash danced himself sick. b. ?e1?e2?x?y?s(Flash(x)?Causer(x,e1)?Cause(e1,e2)?Flash(y)? Actor(y,e2) ? Dance(e2) ?Cul(e2,s) ?Theme(y,s) ?Sick(s)) 4Notably, on such an account, the external...

  4. 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

  5. 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

  6. 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

  7. 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

  8. A CHARACTERIZATION OF SUBSPACES AND QUOTIENTS OF REFLEXIVE BANACH SPACES WITH UNCONDITIONAL

    E-print Network

    Johnson, William B.

    A CHARACTERIZATION OF SUBSPACES AND QUOTIENTS OF REFLEXIVE BANACH SPACES Abstract.We prove that the dual or any quotient of a separable reflexive Banach space that a separable reflexive Banach space * *with the unconditional tree property embeds into a reflexive

  9. TOTALLY REFLEXIVE MODULES CONSTRUCTED FROM SMOOTH PROJECTIVE CURVES OF GENUS g 2

    E-print Network

    Takahashi, Ryo

    TOTALLY REFLEXIVE MODULES CONSTRUCTED FROM SMOOTH PROJECTIVE CURVES OF GENUS g 2 RYO TAKAHASHI two, we construct a non-Gorenstein Cohen-Macaulay normal domain and a nonfree totally reflexive module-dimension zero are called totally reflexive. Any finitely generated free module is totally reflexive. Over

  10. Behavioral/Systems/Cognitive The Differential Role of Motor Cortex in Stretch Reflex

    E-print Network

    Perreault, Eric J.

    Behavioral/Systems/Cognitive The Differential Role of Motor Cortex in Stretch Reflex Modulation 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

  11. 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,…

  12. Reflexive research ethics in fetal tissue xenotransplantation research.

    PubMed

    Panikkar, Bindu; Smith, Natasha; Brown, Phil

    2012-01-01

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

  13. 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)

  14. Nasal reflexes: implications for exercise, breathing, and sex.

    PubMed

    Baraniuk, James N; Merck, Samantha J

    2008-04-01

    Nasal patency, with both congestion and decongestion, is affected in a wide variety of reflexes. Stimuli leading to nasal reflexes include exercise; alterations of body position, pressure, and temperature; neurologic syndromes; and dentistry. As anticipated, the vagal and trigeminal systems are closely integrated through nasobronchial and bronchonasal reflexes. However, perhaps of greater pathophysiologic importance are the naso-hypopharyngeal-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, which by any other name would still smell as sweetly. PMID:18417057

  15. 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.

  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. 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.

  18. 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

  19. 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

  20. 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

  1. 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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Bach, Dominik R

    2015-04-01

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

  4. 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

  5. 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.

  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. 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.

  10. 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

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

    PubMed

    Wurm, Barbara

    2009-03-01

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

  12. Diffuse radio emission in a REFLEX cluster

    E-print Network

    L. Feretti; P. Schuecker; H. Boehringer; F. Govoni; G. Giovannini

    2005-08-16

    Deep Very Large Array radio observations are presented for the REFLEX clusters RXCJ0437.1+0043 and RXCJ1314.4-2515. They are at similar distance and show similar X-ray luminosity, but they are quite different in X-ray structure. Indeed RXCJ0437.1+0043 is regular and relaxed, whereas RXCJ1314.4-2515 is characterized by substructure and possible merging processes. The radio images reveal no diffuse emission in RXCJ0437.1+0043, and a complex diffuse structure in RXCJ1314.4-2515. The diffuse source in the latter cluster consists of a central radio halo which extends to the West toward the cluster periphery and bends to the North to form a possible relic. Another extended source is detected in the eastern cluster peripheral region. Although there could be plausible optical identifications for this source, it might also be a relic candidate owing to its very steep spectrum. The present results confirm the tight link between diffuse cluster radio sources and cluster merger processes.

  13. 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.

  14. 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

  15. 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.

  16. Contributions of dorsal root reflex and axonal reflex to formalin-induced inflammation.

    PubMed

    Hagains, Christopher E; Trevino, Lara A; He, Ji-Wei; Liu, Hanli; Peng, Yuan B

    2010-11-01

    The dorsal root reflex (DRR) and the axonal reflex (AR) are antidromic activities in primary afferents and are involved in neurogenic inflammation. DRRs and/or ARs lead to release of neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP). CGRP causes blood vessels to dilate leading to an increase in blood perfusion, whereas SP causes plasma extravasation, leading to edema. Both DRR and AR can be evoked by noxious stimuli. The goal of this study was to determine the role of DRR and AR in neurogenic inflammation by examining the blood perfusion (BP) change in hindpaws in response to formalin injection (an acute inflammatory agent). Laser Doppler images were collected simultaneously in both hindpaws in anesthetized rats to determine the level of BP. Local lidocaine was applied to the left sciatic nerve to block both orthodromic signals and antidromic DRRs without affecting ARs. All rats then received a subcutaneous formalin injection to the left hindpaw. Our results showed that (1) the mean BP of the left paw increased significantly following formalin injection, with or without lidocaine; (2) application of lidocaine in the left sciatic nerve alone significantly increased BP ipsilaterally; (3) formalin injection following lidocaine application significantly increased BP more than the group without lidocaine; and (4) there was delayed significant BP increase in the right (contralateral) hindpaw following formalin injection with or without lidocaine. It is concluded that ARs play a more important role than DRRs in formalin-induced neurogenic inflammation. PMID:20816764

  17. Measurement of the Achilles tendon reflex for the diagnosis of lumbosacral root compression syndromes.

    PubMed Central

    Rico, R E; Jonkman, E J

    1982-01-01

    The Hoffmann reflex and the Achilles tendon reflex were measured in a group of 194 subjects suspected of having a lumbosacral root compression syndrome. The Achilles tendon reflex was elicited manually with a metal hammer. There was a high correlation between the H-M interval and the Achilles tendon reflex-M interval. The usefulness of the Achilles tendon reflex was evaluated in a selected sub-group of 61 patients with proven L5 or S1 root compression. Neither the H-reflex nor the Achilles tendon reflex appeared to be of any value in detecting L5 root compression. Both the H-reflex and the Achilles tendon reflex proved to be useful for diagnosis of S1 root compression syndromes, the latter being the more sensitive method. Images PMID:7131012

  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. Interaction of Cardiopulmonary and Somatic Reflexes in Humans

    PubMed Central

    Walker, John L.; Abboud, Francois M.; Mark, Allyn L.; Thames, Marc D.

    1980-01-01

    Activation of cardiopulmonary receptors with vagal afferents results predominantly in reflex inhibition of efferent sympathetic activity, whereas activation of somatic receptors reflexly increases sympathetic activity to the heart and circulation. Previous studies in experimental animals indicate that there is an important interaction between these excitatory and inhibitory reflexes in the control of the renal circulation. The purpose of this study was to determine whether there is a similar interaction between somatic and cardiopulmonary reflexes in humans. The activity of the cardiopulmonary receptors was altered (reduced) with lower body negative pressure (?5 mm Hg), which causes a decrease in cardiac filling pressure and a small reflex increase in forearm vascular resistance without accompanying changes in arterial pressure. Activation of somatic receptors by isometric handgrip for 2 min at 10 and 20% of maximum voluntary contraction resulted in reflex vasoconstriction in the nonexercising arm. Lower body negative pressure at ?5 mm Hg produced a threefold augmentation in the forearm vasoconstrictor response to isometric handgrip in the nonexercising arm. This increase in resistance was significantly greater (P < 0.05) than the algebraic sum of the increases in resistance resulting from lower body suction alone plus isometric handgrip alone. Furthermore, it occurred despite a greater rise in arterial pressure, which would be expected to decrease forearm vascular resistance through activation of arterial baroreceptors and through passive dilatation of forearm vessels. Thus, removal of the inhibitory influence of cardiopulmonary receptors by pooling blood in the lower extremities enhances the somatic reflex. These data suggest an interaction between cardiopulmonary and somatic reflexes in the control of forearm vascular resistance in man. PMID:7410553

  20. 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

  1. ESO Reflex: a graphical workflow engine for data reduction

    NASA Astrophysics Data System (ADS)

    Hook, Richard; Ullgrén, Marko; Romaniello, Martino; Maisala, Sami; Oittinen, Tero; Solin, Otto; Savolainen, Ville; Järveläinen, Pekka; Tyynelä, Jani; Péron, Michèle; Ballester, Pascal; Gabasch, Armin; Izzo, Carlo

    ESO Reflex is a prototype software tool that provides a novel approach to astronomical data reduction by integrating a modern graphical workflow system (Taverna) with existing legacy data reduction algorithms. Most of the raw data produced by instruments at the ESO Very Large Telescope (VLT) in Chile are reduced using recipes. These are compiled C applications following an ESO standard and utilising routines provided by the Common Pipeline Library (CPL). Currently these are run in batch mode as part of the data flow system to generate the input to the ESO/VLT quality control process and are also exported for use offline. ESO Reflex can invoke CPL-based recipes in a flexible way through a general purpose graphical interface. ESO Reflex is based on the Taverna system that was originally developed within the UK life-sciences community. Workflows have been created so far for three VLT/VLTI instruments, and the GUI allows the user to make changes to these or create workflows of their own. Python scripts or IDL procedures can be easily brought into workflows and a variety of visualisation and display options, including custom product inspection and validation steps, are available. Taverna is intended for use with web services and experiments using ESO Reflex to access Virtual Observatory web services have been successfully performed. ESO Reflex is the main product developed by Sampo, a project led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. The goal was to look into the needs of the ESO community in the area of data reduction environments and to create pilot software products that illustrate critical steps along the road to a new system. Sampo concluded early in 2008. This contribution will describe ESO Reflex and show several examples of its use both locally and using Virtual Observatory remote web services. ESO Reflex is expected to be released to the community in early 2009.

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

    PubMed

    Schaller, B

    2004-06-01

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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Visual otolith-ocular reflex in normal subjects. A preliminary report

    NASA Astrophysics Data System (ADS)

    Watanabe, Yukio; Shojaku, Hideo; Mizukoshi, Kanemasa; Igarashi, Makoto; Ishii, Masanori; Sekiguchi, Chiharu

    The influence of the otolith-ocular reflex (OOR) induced by the linear (along Y-axis) acceleration was evaluated 12 healthy subjects. The elicited maximum eye velocity (MV) was comparatively analyzed under three stimulus conditions; (1) ) sinusoidal linear acceleration with eyes covered, (2) sinusoidal optokinetic stimulus and (3) sinusoidal linear acceleration with eyes open (visual-vestibular interaction). By the linear acceleration level of 78 cm 2, i.e. 0.08 G, the MV of the optokinetic response (OKR) showed no change in spite of the existence of the OOR.

  8. 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.

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

    PubMed

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

    2001-09-01

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

  10. Human-like reflex control for an artificial hand.

    PubMed

    Folgheraiter, Michele; Gini, Giuseppina

    2004-01-01

    In this paper, we illustrate the low level reflex control used to govern an anthropomorphic artificial hand. The paper develops the position and stiffness control strategy based on dynamic artificial neurons able to simulate the neurons acting in the human reflex control. The controller has a hierarchical structure. At the lowest level there are the receptors able to convert the analogical signal into a neural impulsive signal appropriate to govern the reflex control neurons. Immediately upon it, the artificial motoneurons set the actuators inner pressure to control the finger joint position and moment. Other auxiliary neurons in combination with the motoneurons are able to set the finger stiffness and emulate the inverse myotatic reflex control. Stiffness modulation is important both to save energy during task execution, and to manage objects made of different materials. The inverse myotatic reflex is able to protect the hand from possible harmful external actions. The paper also presents the dynamic model of the joints and of the artificial muscles actuating Blackfingers, our artificial hand. This new type of neural control has been simulated on the Blackfingers model; the results indicate that the developed control is very flexible and efficient for all kind of joints present in the humanoid hand. PMID:15351131

  11. 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.

  12. Persistence of the nasotrigeminal reflex after pontomedullary transection.

    PubMed

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

    2012-03-15

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

  13. 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

  14. 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

  15. 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.

  16. Bilateral vestibular loss, oscillopsia, and the cervico-ocular reflex.

    PubMed

    Chambers, B R; Mai, M; Barber, H O

    1985-06-01

    Oscillopsia during head movement occurs in patients with bilateral vestibular loss and may be transient or persistent. To investigate mechanisms underlying recovery we tested the vestibulo-ocular reflex (VOR), visual-vestibular interaction, and the cervico-ocular reflex (COR); we used a pseudorandom oscillatory stimulus with a frequency band width of 0 to 5 Hz in six patients with bilaterally absent caloric responses and in 10 normal controls. Seven control subjects had low-gain COR responses, but these were anticompensatory with respect to the VOR. Three asymptomatic patients with an absent or grossly deficient VOR had increased oculomotor responses at all frequencies when oscillated in light. Compensatory COR responses were detected in these patients but not in patients with persisting oscillopsia. In some patients with bilateral vestibular loss, augmented cervico-ocular and visual reflexes may compensate, at least partially, for an absent VOR. PMID:3927239

  17. ESO Reflex: A Graphical Workflow Engine for Astronomical Data Reduction

    NASA Astrophysics Data System (ADS)

    Hook, Richard; Romaniello, Martino; Ullgrén, Marko; Maisala, Sami; Solin, Otto; Oittinen, Tero; Savolainen, Villa; Järveläinen, Pekka; Tyynelä, Jani; Péron, Michèle; Izzo, Carlo; Ballester, Pascal; Gabasch, Armin

    2008-03-01

    ESO Reflex is a software tool that provides a novel approach to astronomical data reduction. The reduction sequence is rendered and controlled as a graphical workflow. Users can follow and interact with the processing in an intuitive manner, without the need for complex scripting. The graphical interface also allows the modification of existing workflows and the creation of new ones. ESO Reflex can invoke standard ESO data reduction recipes in a flexible way. Python scripts, IDL procedures and shell commands can also be easily brought into workflows and a variety of visualisation and display options, including custom product inspection and validation steps, are available. ESO Reflex was developed in the context of the Sampo project, a three-year effort led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. It is planned that the software will be released to the community in late 2008.

  18. Reflexive Numbers and Berger Graphs from Calabi-Yau Spaces

    E-print Network

    L. N. Lipatov; A. Sabio Vera; V. N. Velizhanin; G. G. Volkov

    2005-12-21

    We review the Batyrev approach to Calabi-Yau spaces based on reflexive weight vectors. The Universal CY algebra gives a possibility to construct the corresponding reflexive numbers in a recursive way. A physical interpretation of the Batyrev expression for the Calabi-Yau manifolds is presented. Important classes of these manifolds are related to the simple-laced and quasi-simple-laced numbers. We discuss the classification and recurrence relations for them in the framework of quantum field theory methods. A relation between the reflexive numbers and the so-called Berger graphs is studied. In this correspondence the role played by the generalized Coxeter labels is highlighted. Sets of positive roots are investigated in order to connect them to possible new algebraic structures stemming from the Berger matrices.

  19. 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

  20. 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

  1. 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

  2. The structure of reflexive regular splicing languages via Schutzenberger constants \\Lambda

    E-print Network

    Bonizzoni, Paola

    The structure of reflexive regular splicing languages via Sch¨utzenberger constants \\Lambda Paola for a special class of a finite splicing systems, termed reflexive splicing systems, according to each

  3. 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.

  4. 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

  5. EXISTENCE OF A NON-REFLEXIVE EMBEDDING WITH BIRATIONAL GAUSS MAP FOR A PROJECTIVE VARIETY

    E-print Network

    Kaji, Hajime

    EXISTENCE OF A NON-REFLEXIVE EMBEDDING WITH BIRATIONAL GAUSS MAP FOR A PROJECTIVE VARIETY ( ) ( / ) , , non- reflexive , . K p 0 , X PN ( ) n . X x Xsm TxX , X G(n, PN ) . C(X) = {(x, H) Xsm Ã? PN |Tx = PN C(X ) PN Ã? PN . C(X) C(X ) PN Ã? PN , X reflexive . X reflexive X = X . Monge-Segre-Wallace ([4

  6. 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

  7. The blood pressure buffering capacity of nitric oxide by comparison to the baroreceptor reflex

    E-print Network

    Just, Armin

    The blood pressure buffering capacity of nitric oxide by comparison to the baroreceptor reflex A buffering capacity of nitric oxide by comparison to the baroreceptor reflex. Am. J. Physiol. 267 (Heart Circ-term and circadian fluctuations of arterial blood pressure with that of the barore- ceptor reflex, conscious

  8. A CHARACTERIZATION OF SUBSPACES AND QUOTIENTS OF REFLEXIVE BANACH SPACES WITH UNCONDITIONAL

    E-print Network

    Johnson, William B.

    A CHARACTERIZATION OF SUBSPACES AND QUOTIENTS OF REFLEXIVE BANACH SPACES WITH UNCONDITIONAL BASES W reflexive Banach space with the unconditional tree property has the unconditional tree property. This is used to prove that a separable reflexive Banach space with the unconditional tree property embeds

  9. REFLEXIVE COLLISION RESPONSE WITH VIRTUAL SKIN Roadmap Planning Meets Reinforcement Learning

    E-print Network

    Förster, Alexander

    REFLEXIVE COLLISION RESPONSE WITH VIRTUAL SKIN Roadmap Planning Meets Reinforcement Learning with reflexive collision response, which allows the roadmap representation to be transformed into a Markov of the map can be phrased as a reinforcement learn- ing problem. An implementation of the reflexive collision

  10. 716revision:2000-02-19modified:2000-02-19 Decompositions of Reflexive Modules

    E-print Network

    Shelah, Saharon

    716revision:2000-02-19modified:2000-02-19 Decompositions of Reflexive Modules R¨udiger G a stronger and also more general result we will concentrate on reflexive modules over countable principal ideal domains R. Following H. Bass [1] an R-module G is reflexive if the evaluation map : G - G

  11. Asymmetry of Hindlimb Muscle Activity and Cutaneous Reflexes After Tendon Transfers in Kittens

    E-print Network

    Meng, Ellis

    Asymmetry of Hindlimb Muscle Activity and Cutaneous Reflexes After Tendon Transfers in Kittens G. E, Ontario K7L 3E6, Canada Loeb, G. E. Asymmetry of hindlimb muscle activity and cutaneous reflexes after action. In these animals and in the sham-operation controls, the patterns of muscle activity and reflexes

  12. Improved Upper Bounds on the Reflexivity of Point Sets Eyal Ackerman

    E-print Network

    Improved Upper Bounds on the Reflexivity of Point Sets Eyal Ackerman Oswin Aichholzer Bal´azs Keszegh April 22, 2008 Abstract Given a set S of n points in the plane, the reflexivity of S, (S), is the minimum number of reflex vertices in a simple polygonalization of S. Arkin et al. [4] proved that (S) n/2

  13. Poisson's equation and characterizations of reflexivity of Banach spaces Vladimir P. Fonf, Michael Lin

    E-print Network

    Wojtaszczyk, Przemyslaw

    Poisson's equation and characterizations of reflexivity of Banach spaces Vladimir P. Fonf, Michael with a basis. We prove that X is reflexive if and only if every power-bounded linear operator T satisfies Browder's equality x X : sup n n k=1 Tk x reflexive

  14. The Modulation of Visual Orienting Reflexes Across the Lifespan Journal: Developmental Science

    E-print Network

    Handy, Todd C.

    Review Copy Only The Modulation of Visual Orienting Reflexes Across the Lifespan Journal Orienting Across the Lifespan 2 Abstract The development of reflexive and voluntary shifts of visual in the visual field. Relations between reflexive and voluntary shifts of attention were gauged by the degree

  15. Implementation of Long-distance Reflexives in Korean A Categorial Grammar Approach

    E-print Network

    Implementation of Long-distance Reflexives in Korean A Categorial Grammar Approach Yong-hun Lee This paper provides computational algorithms for a Korean reflexive caki, for which both sentence readings of caki with the same resolution mechanisms, while the difference is where the reflexive

  16. (904)revision:2010-09-17modified:2010-09-19 REFLEXIVE ABELIAN GROUPS AND MEASURABLE

    E-print Network

    Shelah, Saharon

    (904)revision:2010-09-17modified:2010-09-19 REFLEXIVE ABELIAN GROUPS AND MEASURABLE CARDINALS. Answering problem (DG) of [1], [2], we show that there is a reflexive group of cardinality which equals to the first measurable cardinal. Anotated Contents §0 Introduction §1 A reflexive group above the first

  17. A CHANGE OF RINGS RESULT FOR MATLIS REFLEXIVITY DOUGLAS J. DAILEY AND THOMAS MARLEY

    E-print Network

    Deng, Bo

    A CHANGE OF RINGS RESULT FOR MATLIS REFLEXIVITY DOUGLAS J. DAILEY AND THOMAS MARLEY Abstract. Let R-module M is (Matlis) reflexive if the natural evaluation map M- HomR(HomR(M, E), E) is an isomorphism. We prove that if S is a multiplicatively closed subset of R and M is a reflexive R-module, then M

  18. Improved Upper Bounds on the Reflexivity of Point Sets Eyal Ackerman

    E-print Network

    Improved Upper Bounds on the Reflexivity of Point Sets Eyal Ackerman Oswin Aichholzer Bal´azs Keszegh Abstract Given a set S of n points in the plane, the reflexivity of S, (S), is the minimum number of reflex vertices in a simple polygonalization of S. Arkin et al. [4] proved that (S) n/2 for any set S

  19. Planning of Ballistic Movement following Stroke: Insights from the Startle Reflex

    E-print Network

    Perreault, Eric J.

    Planning of Ballistic Movement following Stroke: Insights from the Startle Reflex Claire Fletcher. The acoustic startle reflex provides a means to initiate a motor plan involuntarily. In the presence startle reflex, which primarily influences flexor muscles and adapts rapidly with successive stimuli

  20. Using Auditory and Visual Stimuli to Investigate the Behavioral and Neuronal Consequences of Reflexive Covert Orienting

    E-print Network

    Munoz, Douglas Perry

    of Reflexive Covert Orienting Andrew H. Bell, Jillian H. Fecteau, and Douglas P. Munoz Centre for Neuroscience stimuli to investigate the behavioral and neuronal conse- quences of reflexive covert orienting. J Neurophysiol 91: 2172­2184, 2004. First published December 31, 2003; 10.1152/jn.01080.2003. Reflexively

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

    E-print Network

    Hip angle induced modulation of H reflex amplitude, latency and duration in spinal cord injured Abstract Objectives: To investigate the modulation of the soleus H reflex in spinal cord injured (SCI) subjects resulting from imposed changes in hip angle and to establish whether changes in H reflex amplitude

  2. BRAUERTHRALL FOR TOTALLY REFLEXIVE MODULES LARS WINTHER CHRISTENSEN, DAVID A. JORGENSEN, HAMIDREZA RAHMATI,

    E-print Network

    Striuli, Janet

    BRAUER­THRALL FOR TOTALLY REFLEXIVE MODULES LARS WINTHER CHRISTENSEN, DAVID A. JORGENSEN, HAMIDREZA that is not Goren- stein. It is known that the category of totally reflexive modules over R is representation complex the category of totally reflexive modules can be in this situation. Local rings (R, m) with m3 = 0

  3. Reflex: System and Programming Support for Efficient Sensor Use in Mobile Systems

    E-print Network

    Zhong, Lin

    Reflex: System and Programming Support for Efficient Sensor Use in Mobile Systems Xiaozhu Lin1 led us to develop Reflex, a framework that manages sen- sor use with programming and operating abstractions called channels for sensor data processing. Reflex provides three mechanisms. 1) It uses a runtime

  4. Reflex: Managing Sensor Data Processing in Mobile Systems Technical Report 03-15-2010

    E-print Network

    Zhong, Lin

    1 Reflex: Managing Sensor Data Processing in Mobile Systems Technical Report 03-15-2010 Xiaozhu Lin of efficient sensor data processing. Reflex pro- vides a programming and operating abstraction, called channel, and a runtime system that manages the execution of channels, called channel manager. Reflex allows multiple

  5. Diamond graphs and super-reflexivity William B. Johnsonyand Gideon Schechtmanz

    E-print Network

    Johnson, William B.

    * Diamond graphs and super-reflexivity The main result is that a Banach space X is not super-reflexive if and * *only if the diamond graphs super reflexive spac* *e with non trivial type. We also introduce the concept of Lipschitz

  6. Vestibular control of the head: possible functions of the vestibulocollic reflex

    E-print Network

    REVIEW Vestibular control of the head: possible functions of the vestibulocollic reflex Jay M March 2011 Ó Springer-Verlag 2011 Abstract Here, we review the angular vestibulocollic reflex (VCR as a result of the head's underdamped mechanics. The reflex appears unaffected when the simplest, trisynaptic

  7. SPECIAL REFLEXIVE GRAPHS IN MODULAR VARIETIES MARINO GRAN AND JIRI ROSICKY

    E-print Network

    Rosický, Jirí

    SPECIAL REFLEXIVE GRAPHS IN MODULAR VARIETIES MARINO GRAN AND JIR´I ROSICK´Y Abstract. We investigate a special kind of reflexive graphs in any congruence modular variety. When the variety is Maltsev these special reflexive graphs are exactly the internal groupoids, when the variety is distributive

  8. Shape effects on reflexive spatial selective attention and a plausible neurophysiological model q

    E-print Network

    Sereno, Anne B.

    Shape effects on reflexive spatial selective attention and a plausible neurophysiological model q: Received 16 November 2009 Received in revised form 3 April 2010 Keywords: Reflexive spatial attention Shape that this spatial cueing effect (termed reflexive spatial attention) is affected by non-spatial cue and target

  9. A UNIVERSAL REFLEXIVE SPACE FOR THE CLASS OF UNIFORMLY CONVEX BANACH SPACES

    E-print Network

    Schlumprecht, Thomas B.

    A UNIVERSAL REFLEXIVE SPACE FOR THE CLASS OF UNIFORMLY CONVEX BANACH SPACES E. ODELL AND TH. SCHLUMPRECHT Dedicated to the memory of V. I. Gurarii Abstract. We show that there exists a separable reflexive a problem of J. Bourgain. We also give intrinsic characterizations of separable reflexive Banach spaces

  10. STUDIA MATHEMATICA 185 (1) (2008) On operators from separable reflexive spaces

    E-print Network

    Goldstein, Jerome A.

    2008-01-01

    STUDIA MATHEMATICA 185 (1) (2008) On operators from separable reflexive spaces with asymptotic structure by Bentuo Zheng (Austin, TX) Abstract. Let 1 reflexive Banach-dimensional spaces. In particular, T factors through a subspace of a reflexive space with an (p, q) FDD. Similarly

  11. Validation of reflex indicators for measuring vitality and predicting the delayed mortality of wild coho

    E-print Network

    Hinch, Scott G.

    Validation of reflex indicators for measuring vitality and predicting the delayed mortality of wild applied utility is limited because it cannot easily be used by stakeholders. 2. Reflex action mortality predictors (RAMP) is a method that involves checking for the presence or absence of natural animal reflexes

  12. Fully Reflexive Intensional Type Analysis # Valery Trifonov Bratin Saha Zhong Shao

    E-print Network

    Fully Reflexive Intensional Type Analysis # Valery Trifonov Bratin Saha Zhong Shao Department analysis. By fully reflexive, we mean that type­analyzing operations are applicable to the type of any remains decidable. We show how to use reflexive type analysis to support type­safe marshalling and how

  13. 568revision:2000-01-31modified:2000-02-19 Some Nasty Reflexive Groups

    E-print Network

    Shelah, Saharon

    568revision:2000-01-31modified:2000-02-19 Some Nasty Reflexive Groups R¨udiger G¨obel and Saharon . Is this always the case? Also note that reflexive groups G in the sense of H. Bass are dual groups because axiom for 1 (1 ) we will construct a reflexive torsion-free abelian group of cardinality 1 which

  14. Towards Local Reflexive Control of a Powered Transfemoral Prosthesis for Robust Amputee Push and Trip Recovery

    E-print Network

    Geyer, Hartmut

    Towards Local Reflexive Control of a Powered Transfemoral Prosthesis for Robust Amputee Push suggests that control strategies based on local reflexes exhibit robustness to unobserved terrain such as slopes and steps. Therefore, we propose that a powered knee-ankle prosthesis governed by reflexive local

  15. BRAUERTHRALL FOR TOTALLY REFLEXIVE MODULES OVER LOCAL RINGS OF HIGHER DIMENSION

    E-print Network

    Takahashi, Ryo

    BRAUER­THRALL FOR TOTALLY REFLEXIVE MODULES OVER LOCAL RINGS OF HIGHER DIMENSION OLGUR CELIKBAS has a pair {x, y} of exact zerodivisors such that dim R/(x, y) 2 and all totally reflexive R of totally reflexive R-modules. More precisely, we prove that, for infinitely many integers n, there exists

  16. Fully Reflexive Intensional Type Analysis # Bratin Saha Valery Trifonov Zhong Shao

    E-print Network

    Fully Reflexive Intensional Type Analysis # Bratin Saha Valery Trifonov Zhong Shao Department the type of any runtime value. We present a typed intermediate language that supports fully reflexive intensional type analysis. By fully reflexive, we mean that type­analyzing operations are applicable

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

    E-print Network

    Perreault, Eric J.

    Stretch sensitive reflexes as an adaptive mechanism for maintaining limb stability Jonathan, Northwestern University Abstract The often studied stretch reflex is fundamental to the involuntary control have demonstrated that stretch reflexes can be modulated in a task appropriate manner. This review

  18. Reflexive Scott domains are not complete for the extensional lambda calculus Alberto Carraro

    E-print Network

    Salibra, Antonino

    Reflexive Scott domains are not complete for the extensional lambda calculus Alberto Carraro the least -theory or the least extensional -theory . In this paper we analyze the class of reflexive Scott). The following are the main results of the paper: (i) Extensional reflexive Scott domains are not complete

  19. J. Physiol. (I956) I33, 446-455 A COMPARISON OF FLEXOR AND EXTENSOR REFLEXES

    E-print Network

    Hubel, David

    446 J. Physiol. (I956) I33, 446-455 A COMPARISON OF FLEXOR AND EXTENSOR REFLEXES OF MUSCULAR ORIGIN of decerebrate mammalian preparations usually present both phasic and tonic reflex contraction to stretch (Liddell & Sherring- ton, 1925), flexor muscles present phasic stretch reflexes only (Asayama, 1916). Under

  20. 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…

  1. CHARACTERISATION OF REFLEXIVITY BY EQUIVALENT RENORMING PETR H AJEK AND MICHAL JOHANIS

    E-print Network

    Johanis, Michal

    CHARACTERISATION OF REFLEXIVITY BY EQUIVALENT RENORMING PETR H ´AJEK AND MICHAL JOHANIS ABSTRACT a renorming characteri- sation of the class of all reflexive Banach spaces. Renorming characterisation, the most spectacular result in this area is certainly the Enflo-Pisier characterisation of super-reflexive

  2. WITHDRAWAL REFLEXES IN THE UPPER LIMB ADAPT TO ARM POSTURE AND STIMULUS LOCATION

    E-print Network

    Perreault, Eric J.

    WITHDRAWAL REFLEXES IN THE UPPER LIMB ADAPT TO ARM POSTURE AND STIMULUS LOCATION CARRIE L. PETERSON, USA Accepted 31 July 2013 ABSTRACT: Introduction: Withdrawal reflexes in the leg adapt in a context-appropriate manner to remove the limb from noxious stimuli, but the extent to which withdrawal reflexes adapt

  3. 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…

  4. REFLEXIVITY, FACTORIZATION, AND HANKEL OPERATORS EDWARD AZOFF, RUBEN A. MARTINEZ-AVENDA~NO, AND JAMES SOLAZZO

    E-print Network

    Solazzo, James

    REFLEXIVITY, FACTORIZATION, AND HANKEL OPERATORS EDWARD AZOFF, RUB´EN A. MART functions, and we apply work of V. Kapustin on Jordan models to characterize which submodules are reflex- ive in terms of the canonical factorization of these functions. We also prove that reflexivity of any

  5. Fully Reflexive Intensional Type Analysis Valery Trifonov Bratin Saha Zhong Shao

    E-print Network

    Fully Reflexive Intensional Type Analysis Valery Trifonov Bratin Saha Zhong Shao Department analysis. By fully reflexive, we mean that type-analyzing operations are applicable to the type of any remains decidable. We show how to use reflexive type analysis to support type-safe marshalling and how

  6. Fully Reflexive Intensional Type Analysis Bratin Saha Valery Trifonov Zhong Shao

    E-print Network

    Fully Reflexive Intensional Type Analysis Bratin Saha Valery Trifonov Zhong Shao Department the type of any runtime value. We present a typed intermediate language that supports fully reflexive intensional type analysis. By fully reflexive, we mean that type-analyzing operations are applicable

  7. HigherOrder and Reflexive Action Calculi: Their Type Theory and Models 1

    E-print Network

    Hasegawa, Masahito

    Higher­Order and Reflexive Action Calculi: Their Type Theory and Models 1 Philippa Gardner \\Lambda Running Head: Higher­Order and Reflexive Action Calculi Corresponding Author: Masahito Hasegawa Research calculi, which add higher­order features to the basic setting, and the reflexive action calculi, which

  8. Challenges in practical computation of global sensitivities with application to a baroreceptor reflex model

    E-print Network

    reflex model Christian Haargaard Olsen1,2 , Hien Tran3 , Johnny T. Ottesen4 , Jesper Mehlsen2 and Mette S computation using a baroreceptor reflex model, which describes heart rate regulation during head-up tilt. Conclusions: Global sensitivities were calculated for an improved baroreceptor reflex model, by averaging

  9. RAPID COMMUNICATION Reflex Suppression in the Anti-Saccade Task Is Dependent on

    E-print Network

    Munoz, Douglas Perry

    RAPID COMMUNICATION Reflex Suppression in the Anti-Saccade Task Is Dependent on Prestimulus Neural Everling, Stefan, Michael C. Dorris, and Douglas P. Munoz. tions, why can subjects suppress a reflexive response on some Reflex suppression in the anti-saccade task is dependent on prestim- trials yet fail

  10. Complex Oscillations in the Human Pupil Light Reflex with "Mixed" and Delayed Feedback*

    E-print Network

    Longtin, André

    Complex Oscillations in the Human Pupil Light Reflex with "Mixed" and Delayed Feedback* ANDRE pupil light reflex with piecewise constant mixed and delayed feedback. The output of an infrared video by the light reflex has been extensively studied as an example of a neurological control system [19

  11. Impairment of the Transient Pupillary Light Reflex Mice and Humans with Leber

    E-print Network

    Palczewski, Krzysztof

    level is conveyed through the afferent arc of the reflex, which includes retinal ganglion cells through the efferent arc of the reflex toward the ciliary ganglion, where the last synapse occursImpairment of the Transient Pupillary Light Reflex in Rpe65 / Mice and Humans with Leber Congenital

  12. Neuroscience Letters 380 (2005) 305310 The intralimb coordination of the flexor reflex response is altered

    E-print Network

    2005-01-01

    Neuroscience Letters 380 (2005) 305­310 The intralimb coordination of the flexor reflex response study compared the intralimb coordination of flexor reflex responses in spinal intact and complete and 19 spinal intact volunteers and the flexor reflex response was quantified by measuring the isometric

  13. 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.

  14. 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

  15. Ontogeny of Infantile Oral Reflexes and Emerging Chewing.

    ERIC Educational Resources Information Center

    Sheppard, Justine Joan; Mysak, Edward D.

    1984-01-01

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

  16. Vestibuloocular Reflex Signal Modulation During Voluntary and Passive Head Movements

    E-print Network

    to the differential processing of head-velocity information by PVP neurons. We show that neither neck proprioceptiveVestibuloocular Reflex Signal Modulation During Voluntary and Passive Head Movements JEFFERSON E and passive head movements. J Neurophysiol 87: 2337­2357, 2002; 10.1152/jn.00625.2001. The vestibuloocular

  17. The modulation of visual orienting reflexes across the lifespan.

    PubMed

    Iarocci, Grace; Enns, James T; Randolph, Beth; Burack, Jacob A

    2009-09-01

    The development of reflexive and voluntary shifts of visual attention, as well as relations between the two forms of shifting, were examined in three groups of children (5, 7, and 9 years old), one group of young adults (24 years old), and two groups of senior adults (young seniors with an average age of 69 years, and old seniors with an average age of 81 years). The task entailed response to the detection of a target (black dot) in one of four possible locations in the visual field. Relations between reflexive and voluntary shifts of attention were gauged by the degree to which flash and arrow facilitation and inhibition were observed in response to the presentation of both arrow and flash cues together in one trial. All age groups oriented reflexively in response to a flash cue and utilized the arrow cue to orient attention strategically. When flash and arrow cues were presented in quick succession and thereby competed for attention, the youngest children and oldest seniors were least efficient and flexible in their approach to the orienting task as they had difficulty modulating visual reflexes. PMID:19702764

  18. 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…

  19. 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...

  20. 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…

  1. 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…

  2. 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

  3. Reflexive Loopers for Solo Musical Improvisation Franois Pachet

    E-print Network

    d'Inverno, Mark

    Reflexive Loopers for Solo Musical Improvisation François Pachet Sony CSL 6, rue Amyot pachet@csl.sony.fr Pierre Roy Sony CSL 6, rue Amyot roy@csl.sony.fr Julian Moreira Sony CSL 6, rue Amyot moreira@csl.sony.fr Goldsmiths & Sony CSL dinverno@gold.ac.uk ABSTRACT Loop pedals are real-time samplers that playback audio

  4. Language Constructing Language: The Implications of Reflexivity for Linguistic Theory.

    ERIC Educational Resources Information Center

    Taylor, Talbot J.

    2000-01-01

    Asks what first-order language might be like if there were no way to talk, write, or sign about it--that is, what if there were no second-order metalanguage. By considering the consequences for writing, translation, pragmatics, semantics, and language acquisition and evolution, it is suggested that without second-order, reflexive properties,…

  5. 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

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  12. 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

  13. 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

  14. 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.

  15. [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

  16. Baroreceptor reflex control of heart rate in angiotensin type 1A receptor knockout mice

    PubMed Central

    Choong, Yan-Ting; Menuet, Clement; Jancovski, Nikola; Allen, Andrew M

    2013-01-01

    The baroreceptor reflex dampens the short-term fluctuations in blood pressure by feedback modulation of heart rate (HR) and vascular resistance. Impairment of this reflex has been observed in hypertension and heart failure. Angiotensin II, a blood borne hormone, acts via its type 1A receptor to attenuate the baroreceptor reflex and this reflex is reported to be dramatically altered in angiotensin type 1A receptor knockout mice. This study sought to further investigate changes in the arterial and cardiopulmonary baroreceptor reflex control of HR in angiotensin II type 1A receptor knocked out mice. In artificially ventilated, isoflurane anesthetized mice, the arterial and cardiopulmonary baroreceptor reflexes were activated via injection or slow infusions, respectively, of phenylephrine and sodium nitroprusside through the jugular vein. We observed no impairment of either the arterial or cardiopulmonary baroreceptor reflex control of HR in angiotensin type 1A receptor knockout mice. PMID:24400170

  17. arXiv:cs/0210003v2[cs.CG]2Oct2002 On the Reflexivity of Point Sets

    E-print Network

    Fekete, Sándor P.

    arXiv:cs/0210003v2[cs.CG]2Oct2002 On the Reflexivity of Point Sets Esther M. Arkin S´andor P a convex set: The reflexivity (S) of S is given by the smallest number of reflex vertices in a simple reflexivity, both exactly (in special cases) and ap- proximately (in general). Our study considers also some

  18. Hanseth et al./Reflexive Standardization MIS Quarterly Vol. 30 Special Issue, pp. 1-XXX/Forthcoming 2006 1

    E-print Network

    Hanseth, Ole

    Hanseth et al./Reflexive Standardization MIS Quarterly Vol. 30 Special Issue, pp. 1-XXX/Forthcoming 2006 1 SPECIAL ISSUE REFLEXIVE STANDARDIZATION: SIDE EFFECTS AND COMPLEXITY IN STANDARD MAKING 1 By and upon reflexivity and the unexpected side effects adopted from reflexive modernization, the paper makes

  19. Abstract We examined the amplitude modulation of the soleus (Sol) H-reflex during controlled variations of the

    E-print Network

    Abstract We examined the amplitude modulation of the soleus (Sol) H-reflex during controlled position, flexion of the hip significantly de- pressed Sol H-reflex excitability, by as much as 50% of control reflex values (Ho) recorded at 10° of hip flexion. Conversely, significant facilitation of the H-reflex

  20. Decidability of the Logics of the Reflexive Sub-interval and Super-interval Relations over Finite Linear Orders

    E-print Network

    Pratt-Hartmann, Ian

    Decidability of the Logics of the Reflexive Sub-interval and Super-interval Relations over Finite consider the modal operators based on the (reflexive) sub- interval relation and the (reflexive) super. There are three natural definitions of the sub-interval relation [5]: reflexive (the current interval is a sub

  1. '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.

  2. Diving reflex: can the time course of heart rate reduction be quantified?

    PubMed

    Caspers, C; Cleveland, S; Schipke, J D

    2011-02-01

    In this meta-analysis of diving bradycardia in humans, we sought to quantify any heart rate (HR) reduction using a relatively simple mathematical function. Using the terms "diving reflex,"diving bradycardia,"diving response,"diving plus heart rate," databases were searched. Data from the studies were fitted using HR=c+aexp(-(t-t(0))/?), where c is the final HR, a is the HR decrease, ? is the time constant of HR decay, and t(0) is the time delay. Of 890 studies, 220 were given closer scrutiny. Only eight of these provided data obtained under comparable conditions. Apneic facial immersion decreased HR with ?=10.4 s and in air alone it was less pronounced and slower (?=16.2 s). The exponential function fitted the time course of HR decrease closely (r(2)>0.93). The fit was less adequate for apneic-exercising volunteers. During apnea both with and without face immersion, HR decreases along a monoexponential function with a characteristic time constant. HR decrease during exercise with and without face immersion could not readily be described with a simple function: the parasympathetic reaction was partially offset by some sympathetic activity. Thus, we succeeded in quantifying the early time course of diving bradycardia. It is concluded that the diving reflex is useful to diagnose the integrity of efferent cardiovascular autonomic pathways. PMID:21083770

  3. Trigeminal reflex regulation of the glottis depends on central glycinergic inhibition in the rat.

    PubMed

    Dutschmann, Mathias; Paton, Julian F R

    2002-04-01

    In an unanesthetized decerebrate in situ arterially perfused brain stem preparation of mature rat, strychnine (0.05-0.2 microM) blockade of glycine receptors caused postinspiratory glottal constriction to occur earlier, shifting from early expiration to inspiration. This resulted in a paradoxical inspiratory-related narrowing of the upper airway. Stimulation of the trigeminal ethmoidal nerve (EN5; 20 Hz, 100 micros, 0.5-2 V) evoked a diving response, which included a reflex apnea, glottal constriction, and bradycardia. After strychnine administration, this pattern was converted to a maintained phrenic nerve discharge and a reduced glottal constriction that was interrupted intermittently by transient abductions. The onset of firing of postinspiratory neurons shifted from early expiration into neural inspiration in the presence of strychnine, but neurons maintained their tonic activation during EN5 stimulation, as observed during control. Inspiratory neurons that were hyperpolarized by EN5 stimulation in control conditions were powerfully excited after loss of glycinergic inhibition. Thus the integrity of glycinergic inhibition within the pontomedullary respiratory network is critical for the coordination of cranial and spinal motor outflows during eupnea but also for protective reflex regulation of the upper airway. PMID:11893603

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

    2014-01-01

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

  6. 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.

  7. 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

  8. Reflex myoclonic epilepsy in infancy: a critical review.

    PubMed

    Verrotti, Alberto; Matricardi, Sara; Pavone, Piero; Marino, Raffaella; Curatolo, Paolo

    2013-06-01

    Benign myoclonic epilepsy in infancy, classified among the generalised idiopathic epilepsies, is characterised by the occurrence of myoclonic seizures in the first three years of life in otherwise normal infants. Some authors have described cases of myoclonic seizures as a reflex response to sudden unexpected tactile or acoustic stimuli and this clinical entity has been proposed as a separate nosographic syndrome, referred to as "reflex myoclonic epilepsy in infancy" (RMEI). We reviewed all published articles and case reports on RMEI in order to clarify clinical and electroencephalographic findings, with particular attention to outcome and treatment. RMEI appears to be a benign variant of idiopathic myoclonic epilepsy in infancy with specific features that occur in neurologically and developmentally normal children. This rare clinical entity is often under-described and under-diagnosed, and for this reason should be brought to the attention of paediatricians in order to avoid extensive investigations and reassure parents of the lack of long-term complications. PMID:23770486

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. ESO Reflex: A Graphical Workflow Engine for Data Reduction

    NASA Astrophysics Data System (ADS)

    Hook, R.; Romaniello, M.; Péron, M.; Ballester, P.; Gabasch, A.; Izzo, C.; Ullgrén, M.; Maisala, S.; Oittinen, T.; Solin, O.; Savolainen, V.; Järveläinen, P.; Tyynelä, J.

    2008-08-01

    Sampo {http://www.eso.org/sampo} (Hook et al. 2005) is a project led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. The goal is to assess the needs of the ESO community in the area of data reduction environments and to create pilot software products that illustrate critical steps along the road to a new system. Those prototypes will not only be used to validate concepts and understand requirements but will also be tools of immediate value for the community. Most of the raw data produced by ESO instruments can be reduced using CPL {http://www.eso.org/cpl} recipes: compiled C programs following an ESO standard and utilizing routines provided by the Common Pipeline Library. Currently reduction recipes are run in batch mode as part of the data flow system to generate the input to the ESO VLT/VLTI quality control process and are also made public for external users. Sampo has developed a prototype application called ESO Reflex {http://www.eso.org/sampo/reflex/} that integrates a graphical user interface and existing data reduction algorithms. ESO Reflex can invoke CPL-based recipes in a flexible way through a dedicated interface. ESO Reflex is based on the graphical workflow engine Taverna {http://taverna.sourceforge.net} that was originally developed by the UK eScience community, mostly for work in the life sciences. Workflows have been created so far for three VLT/VLTI instrument modes ( VIMOS/IFU {http://www.eso.org/instruments/vimos/}, FORS spectroscopy {http://www.eso.org/instruments/fors/} and AMBER {http://www.eso.org/instruments/amber/}), and the easy-to-use GUI allows the user to make changes to these or create workflows of their own. Python scripts and IDL procedures can be easily brought into workflows and a variety of visualisation and display options, including custom product inspection and validation steps, are available.

  14. 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.

  15. 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.

  16. The mammalian diving response: an enigmatic reflex to preserve life?

    PubMed

    Panneton, W Michael

    2013-09-01

    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

  17. Peripheral ?-opioid receptors attenuate the exercise pressor reflex

    PubMed Central

    Yamauchi, Katsuya; Kim, Joyce; Ruiz-Velasco, Victor; Kaufman, Marc P.

    2013-01-01

    In rats with ligated femoral arteries, the exercise pressor reflex is exaggerated, an effect that is attenuated by stimulation of peripheral ?-opioid receptors on group IV metabosensitive afferents. In contrast, ?-opioid receptors are expressed mostly on group III mechanosensitive afferents, a finding that prompted us to determine whether stimulation of these opioid receptors could also attenuate the exaggerated exercise pressor reflex in “ligated” rats. We found femoral arterial injection of [D-Pen2,D-Pen5]enkephalin (DPDPE; 1.0 ?g), a ?-opioid agonist, significantly attenuated the pressor and cardioaccelerator components of the exercise pressor reflex evoked by hindlimb muscle contraction in both rats with ligated and patent femoral arteries. DPDPE significantly decreased the pressor responses to muscle mechanoreflex activation, evoked by tendon stretch, in ligated rats only. DPDPE (1.0 ?g) had no effect in either group on the pressor and cardioaccelerator responses to capsaicin (0.2 ?g), which primarily stimulates group IV afferents. DPDPE (1.0 ?g) had no effect on the pressor and cardioaccelerator responses to lactic acid (24 mM), which stimulates group III and IV afferents, in rats with patent femoral arteries but significantly decreased the pressor response in ligated rats. Western blots revealed the amount of protein comprising the ?-opioid receptor was greater in dorsal root ganglia innervating hindlimbs with ligated femoral arteries than in dorsal root ganglia innervating hindlimbs with patent femoral arteries. Our findings support the hypothesis that stimulation of ?-opioid receptors on group III afferents attenuated the exercise pressor reflex. PMID:23934854

  18. Conditioned Eyelid Movement Is not a Blink

    PubMed Central

    Schade Powers, Alice; Coburn-Litvak, Pamela

    2010-01-01

    Based on kinematic properties and distinct substrates, there are different classes of eyelid movement described as eyeblinks. We investigate whether the eyelid movements made in response to a conditioned stimulus (CS) are a category of eyelid movements distinct from blinks. Human subjects received 60 trials of classical eyelid conditioning with a tone as the CS and electrical stimulation of the supraorbital branch of the trigeminal nerve as the unconditioned stimulus (UCS). Before and after training, reflex blinks were elicited with the UCS. The kinematics of conditioned responses (CRs) differed significantly from those of reflex blinks. The slope of the amplitude-maximum velocity function was steeper for reflex blinks than for CRs, and reflex blink duration was significantly shorter than CR duration. Unlike reflex blinks, for which maximum velocity was independent of blink duration, the maximum velocity of CRs depended on CR duration. These quantitative and qualitative differences indicated that CRs were a unique class of eyelid movements distinct from blinks and eyelid movements with vertical saccadic gaze shifts. PMID:19939960

  19. 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

  20. 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

  1. 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

  2. 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

  3. Vagovagal reflex motility patterns of the rat esophagus.

    PubMed

    Lu, W Y; Bieger, D

    1998-05-01

    Esophageal reflex motility and its neural correlates were investigated in 94 urethan-anesthetized adult male albino rats. When distended by means of a stationary balloon, the cervical and thoracic esophageal portion responded with a single pressure wave (type I response), whereas the diaphragmatic (intercrural) segment exhibited rhythmic contractions (type II response). Balloon deflation resulted in an off response aboral to the balloon. Bilateral cervical vagotomy or systemic D-tubocurarine abolished all types of reflex responses. Both type I and type II responses were associated with multiunit discharges in the central subnucleus of the solitary tract complex (NTSC) and the compact formation of the nucleus ambiguus (AMBC). Type I discharges, consisting of single bursts, and type II discharges, consisting of rhythmic 0.6-Hz bursts, preceded intraesophageal pressure waves in a fixed phase relationship, persisted after contralateral vagotomy, and were eliminated by ipsilateral vagotomy. During neuromuscular paralysis, peak intraburst discharge rates were reduced in both the NTSC and AMBC, with a concomitant decrease in rhythmicity. It is concluded that bolusevoked peristalsis of the rat esophagus is 1) segmentally organized; 2) effected by a bilateral uncrossed reflex arc consisting of vagal viscerosensory, NTSC premotor, and AMBC motoneurons innervating the striated muscle tunic and 3) strongly facilitated by reafferent feedback. PMID:9612411

  4. 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

  5. Mental-state attribution drives rapid, reflexive gaze following.

    PubMed

    Teufel, Christoph; Alexis, Dean M; Clayton, Nicola S; Davis, Greg

    2010-04-01

    When presented with a face stimulus whose gaze is diverted, observers' attention shifts to locations fixated by the face. Such "gaze following" has been characterized by some previous studies as a consequence of sophisticated theory of mind processes, but by others (particularly those employing the "gaze-cuing" paradigm) as an involuntary response that is triggered directly and reflexively by the physical features of a face. To address this apparent contradiction, we modified the gaze-cuing paradigm using a deception procedure to convince observers that prerecorded videos of an experimenter making head turns and wearing mirrored goggles were a "live" video link to an adjacent room. In two experiments, reflexive gaze following was found when observers believed that the model was wearing transparent goggles and could see, but it was significantly reduced when they believed that the experimenter wore opaque goggles and could not see. These results indicate that the attribution of the mental state "seeing" to a face plays a role in controlling even reflexive gaze following. PMID:20348576

  6. 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

  7. 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

  8. Postural proprioceptive reflexes in standing human subjects: bandwidth of response and transmission characteristics.

    PubMed Central

    Fitzpatrick, R C; Gorman, R B; Burke, D; Gandevia, S C

    1992-01-01

    1. This study investigated the reflex control of postural sway during human bipedal stance. The experiments were designed to: (i) find evidence for the operation of 'stretch reflex' pathways during quiet stance, (ii) determine the bandwidth of the reflex response, (iii) describe the reflex transmission characteristics in standing subjects, and (iv) assess the ability of subjects to make a task-dependent change in the reflex. 2. A continuous random perturbation that did not threaten stability was applied at waist level to nine standing subjects. The effects of the perturbation on ankle torque, ankle movement and soleus electromyographic activity (EMG) were identified by cross-correlation. The bandwidth of the reflex response and the transmission characteristics of reflexes that respond to ankle movement were identified by spectral analysis. Changes in these reflex responses were investigated when subjects attempted to stand as still as possible, had their eyes closed, or balanced a load equivalent to their own body in a situation in which neither visual nor vestibular reflexes would be activated. 3. When standing, a reflex response coherent with the perturbation was seen in soleus EMG at frequencies up to 5 Hz, with maximal coherence at 1.0-2.0 Hz. Reflex gain increased with frequency, and there was a frequency-dependent phase advance of soleus EMG on ankle movement reaching 135 deg at 3 Hz. When attempting to minimize sway, subjects produced a more coherent reflex response and significantly increased reflex gain. 4. The response and transmission characteristics of the lower limb proprioceptive reflex in freely standing subjects were similar to those in subjects balancing a load at the ankle, a situation in which vestibular and visual inputs could not contribute. 5. It is concluded that reflex feedback related to ankle movement contributes significantly to maintaining stance, and that much of the reflex response originates from lower limb mechanoreceptors stimulated by ankle rotation. Although reflex gain may be relatively low during quiet stance it can be increased when necessary to maintain stability. PMID:1338796

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

    PubMed

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

    2015-03-01

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

  10. 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

  11. 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

  12. 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.

  13. 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

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

    PubMed

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

    2013-01-01

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

  15. Applied Nietzsche: The Problem of Reflexivity in Habermas, A Postmodern Critique

    E-print Network

    Pickard, Dean

    Nietzsche, has intentionally employed tactics that reveal just this feature of any rational system. The problem of self-reference or of reflexivity in Nietzsche is well known, for example, if Nietzsche's perspectivism is true than it is a counterexample... NIETZSCHE THE PROBLEM OF REFLEXIVITY IN HABERMAS, A POSTMODERN CRITIQUE DEAN PICKARD Claremont Graduate School 1 will be concerned here with the issue of the self-referential or reflexive nature of reason that Nitezsche's perspectivism and anti...

  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. 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).

  18. 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.

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

    PubMed

    LeMoyne, Robert; Mastroianni, Timothy

    2014-01-01

    The patellar tendon reflex constitutes a fundamental aspect of the conventional neurological evaluation. Dysfunctional characteristics of the reflex response can augment the diagnostic acuity of a clinician for subsequent referral to more advanced medical resources. The capacity to quantify the reflex response while alleviating the growing strain on specialized medical resources is a topic of interest. The quantification of the tendon reflex response has been successfully demonstrated with considerable accuracy and consistency through using a potential energy impact pendulum attached to a reflex hammer for evoking the tendon reflex with a smartphone, such as an iPhone, application representing a wireless accelerometer platform to quantify reflex response. Another sensor integrated into the smartphone, such as an iPhone, is the gyroscope, which measures rate of angular rotation. A smartphone application enables wireless transmission through Internet connectivity of the gyroscope signal recording of the reflex response as an email attachment. The smartphone wireless gyroscope application demonstrates considerable accuracy and consistency for the quantification of the tendon reflex response. PMID:25570783

  20. Locomotor training alters the behavior of flexor reflexes during walking in human spinal cord injury.

    PubMed

    Smith, Andrew C; Mummidisetty, Chaithanya K; Rymer, William Zev; Knikou, Maria

    2014-11-01

    In humans, a chronic spinal cord injury (SCI) impairs the excitability of pathways mediating early flexor reflexes and increases the excitability of late, long-lasting flexor reflexes. We hypothesized that in individuals with SCI, locomotor training will alter the behavior of these spinally mediated reflexes. Nine individuals who had either chronic clinically motor complete or incomplete SCI received an average of 44 locomotor training sessions. Flexor reflexes, elicited via sural nerve stimulation of the right or left leg, were recorded from the ipsilateral tibialis anterior (TA) muscle before and after body weight support (BWS)-assisted treadmill training. The modulation pattern of the ipsilateral TA responses following innocuous stimulation of the right foot was also recorded in 10 healthy subjects while they stepped at 25% BWS to investigate whether body unloading during walking affects the behavior of these responses. Healthy subjects did not receive treadmill training. We observed a phase-dependent modulation of early TA flexor reflexes in healthy subjects with reduced body weight during walking. The early TA flexor reflexes were increased at heel contact, progressively decreased during the stance phase, and then increased throughout the swing phase. In individuals with SCI, locomotor training induced the reappearance of early TA flexor reflexes and changed the amplitude of late TA flexor reflexes during walking. Both early and late TA flexor reflexes were modulated in a phase-dependent pattern after training. These new findings support the adaptive capability of the injured nervous system to return to a prelesion excitability and integration state. PMID:25122715

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Higher Weak Derivatives and Reflexive Algebras of Operators

    E-print Network

    Erik Christensen

    2015-07-09

    Let D be a self-adjoint operator on a Hilbert space H and x a bounded operator on H. We say that x is n-times weakly D-differentiable, if for any pair of vectors a, b from H the function is n-times differentiable. We give several characterizations of this property, among which one is original. The results are used to show, that for a von Neumann algebra M on H, the sub-algebra of n-times weakly D-differentiable operators has a representation as a reflexive algebra of operators on a bigger Hilbert space.

  11. 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.

  12. 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.

  13. Fast cerebellar reflex circuitry requires synaptic vesicle priming by munc13-3.

    PubMed

    Netrakanti, Pallavi Rao; Cooper, Benjamin H; Dere, Ekrem; Poggi, Giulia; Winkler, Daniela; Brose, Nils; Ehrenreich, Hannelore

    2015-06-01

    Munc13-3 is a member of the Munc13 family of synaptic vesicle priming proteins and mainly expressed in cerebellar neurons. Munc13-3 null mutant (Munc13-3 (-/-)) mice show decreased synaptic release probability at parallel fiber to Purkinje cell, granule cell to Golgi cell, and granule cell to basket cell synapses and exhibit a motor learning deficit at highest rotarod speeds. Since we detected Munc13-3 immunoreactivity in the dentate gyrus, as reported here for the first time, and current studies indicated a crucial role for the cerebellum in hippocampus-dependent spatial memory, we systematically investigated Munc13-3 (-/-) mice versus wild-type littermates of both genders with respect to hippocampus-related cognition and a range of basic behaviors, including tests for anxiety, sensory functions, motor performance and balance, sensorimotor gating, social interaction and competence, and repetitive and compulsive behaviors. Neither basic behavior nor hippocampus-dependent cognitive performance, evaluated by Morris water maze, hole board working and reference memory, IntelliCage-based place learning including multiple reversals, and fear conditioning, showed any difference between genotypes. However, consistent with a disturbed cerebellar reflex circuitry, a reliable reduction in the acoustic startle response in both male and female Munc13-3 (-/-) mice was found. To conclude, complete deletion of Munc13-3 leads to a robust decrease in the acoustic startle response. This readout of a fast cerebellar reflex circuitry obviously requires synaptic vesicle priming by Munc13-3 for full functionality, in contrast to other behavioral or cognitive features, where a nearly perfect compensation of Munc13-3 deficiency by related synaptic proteins has to be assumed. PMID:25617111

  14. 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

  15. Esophago-Glottal Closure Reflex in Human Infants: A Novel Reflex Elicited With Concurrent Manometry and Ultrasonography

    PubMed Central

    Jadcherla, Sudarshan R.; Gupta, Alankar; Coley, Brian D.; Fernandez, Soledad; Shaker, Reza

    2014-01-01

    BACKGROUND AND AIMS Our aims were to identify and characterize the glottal response to esophageal mechanostimulation in human infants. We tested the hypotheses that glottal response is related to the type of esophageal peristaltic response, stimulus volume, and respiratory phase. METHODS Ten infants (2.8 kg, SD 0.5) were studied at 39.2 wk (SD 2.4). Esophageal manometry concurrent with ultrasonography of the glottis (USG) was performed. The sensory-motor characteristics of mechanostimulation-induced esophago-glottal closure reflex (EGCR, adduction of glottal folds upon esophageal provocation) were identified. Mid-esophageal infusions of air (N 41) were given and the temporal relationships of glottal response with deglutition, secondary peristalsis (SP), and the respiratory phase were analyzed using multinomial logistic regression models. RESULTS The frequency occurrence of EGCR (83%) was compared (P < 0.001) with deglutition (44%), SP (34%), and no esophageal responses (22%). The odds ratios (OR, 95% CI) for the coexistence of EGCR with SP (0.4, 0.06–2.2), deglutition (1.9, 0.1–26), and no response (1.9, 0.4–9.0) were similar. The response time for esophageal reflexes was 3.8 (SD 1.8) s, and for EGCR was 0.4 (SD 0.3) s (P < 0.001). Volume-response relationship was noted (1 mL vs 2 mL, P < 0.05). EGCR was noted in both respiratory phases; however, EGCR response time was faster during expiration (P < 0.05). CONCLUSION The occurrence of EGCR is independent of the peristaltic reflexes or the respiratory phase of infusion. The independent existence of EGCR suggests a hypervigilant state of the glottis to prevent retrograde aspiration during GER events. PMID:17617206

  16. Central Cannabinoid Receptors Modulate Acquisition of Eyeblink Conditioning

    ERIC Educational Resources Information Center

    Steinmetz, Adam B.; Freeman, John H.

    2010-01-01

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

  17. Excitatory amino acid receptors in the caudal ventrolateral medulla mediate a vagal cardiopulmonary reflex in the rat.

    PubMed

    Verberne, A J; Beart, P M; Louis, W J

    1989-01-01

    The importance of the caudal ventrolateral medulla (CVLM) in mediating vagal cardiopulmonary (Bezold-Jarisch reflex) reflex activity was studied in urethane-anaesthetized rats. Unilateral electrolytic lesion of the CVLM markedly attenuated Bezold-Jarisch reflex responses (hypotension and bradycardia) elicited by intravenous injections of 5-HT. Bilateral lesion of the CVLM virtually abolished the reflex responses. Microinjection of the excitatory amino acid (EAA) receptor antagonist kynurenate (KYN), but not the inactive analogue xanthurenate, into the CVLM markedly attenuated the reflex responses to 5-HT. The N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 also markedly attenuated reflex activity. Furthermore, lesions, KYN and MK-801 all tended to elevate resting blood pressure and to reduce resting heart rate. These findings support the hypothesis that the CVLM is an important medullary locus mediating cardiovascular reflex integration and that an EAA synapse in the CVLM is important in the cardiopulmonary reflex arc. PMID:2556290

  18. 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…

  19. Learning VOR-like stabilization reflexes F. Panerai , G. Metta and G. Sandini

    E-print Network

    Sandini, Giulio

    mechanism. In many species, visual stabilization is obtained through reflex eye movements and intriguinglyLearning VOR-like stabilization reflexes in robots F. Panerai ¹, G. Metta ² and G. Sandini ² M through an artificial vestibular apparatus and visually using basic motion detection algorithms. The first

  20. Unsupervised learning of reflexive and action-based affordances to model navigational behavior

    E-print Network

    König, Peter

    Unsupervised learning of reflexive and action-based affordances to model navigational behavior the extent to which these state-to-state transitions are caused by sensory-driven reflex behavior (obstacle that place cells can be understood as an optimally stable representation of the visual input of a behaving

  1. Visual Influences on the Development and Recovery of the Vestibuloocular Reflex in the Chicken

    E-print Network

    Rubel, Edwin

    Visual Influences on the Development and Recovery of the Vestibuloocular Reflex in the Chicken reflex (VOR) helps to maintain a stable image of the visual world on the retina during head movements 2000 Goode, Christopher T., Donna L. Maney, Edwin W Rubel, and Albert F. Fuchs. Visual influences

  2. 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…

  3. 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...

  4. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... in a red and white pattern (see Federal Motor Vehicle Safety Standard No. 108 (49 CFR 571.108), S5.7... 49 Transportation 5 2011-10-01 2011-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December...

  5. 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…

  6. 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.…

  7. 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…

  8. 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…

  9. 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...

  10. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... in a red and white pattern (see Federal Motor Vehicle Safety Standard No. 108 (49 CFR 571.108), S5.7... 49 Transportation 5 2010-10-01 2010-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December...

  11. 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...

  12. 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,…

  13. 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

  14. 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

  15. 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…

  16. Prior experience does not alter modulation of cutaneous reflexes during manual wheeling and symmetrical arm cycling.

    PubMed

    MacGillivray, Megan K; Klimstra, Marc; Sawatzky, Bonita; Zehr, E Paul; Lam, Tania

    2013-05-01

    Previous research has reported that training and experience influence H-reflex amplitude during rhythmic activity; however, little research has yet examined the influence of training on cutaneous reflexes. Manual wheelchair users (MWUs) depend on their arms for locomotion. We postulated that the daily dependence and high amount of use of the arms for mobility in MWUs would show differences in cutaneous reflex modulation during upper limb cyclic movements compared with able-bodied control subjects. We hypothesized that MWUs would demonstrate increased reflex response amplitudes for both manual wheeling and symmetrical arm cycling tasks. The superficial radial nerve was stimulated randomly at different points of the movement cycle of manual wheeling and symmetrical arm cycling in MWUs and able-bodied subjects naive to wheeling. Our results showed that there were no differences in amplitude modulation of early- or middle-latency cutaneous reflexes between the able-bodied group and the MWU group. However, there were several differences in amplitude modulation of cutaneous reflexes between tasks (manual wheeling and symmetrical arm cycling). Specifically, differences were observed in early-latency responses in the anterior and posterior deltoid muscles and biceps and triceps brachii as well as in middle-latency responses in the anterior and posterior deltoid. These data suggest that manual wheeling experience does not modify the pattern of cutaneous reflex amplitude modulation during manual wheeling. The differences in amplitude modulation of cutaneous reflexes between tasks may be a result of mechanical differences (i.e., hand contact) between tasks. PMID:23427304

  17. AZUMAYA ALGEBRAS, REFLEXIVE MODULES, AND PICARD NUMBERS FOR A FAMILY OF RATIONAL SURFACES

    E-print Network

    Ford, Timothy J.

    AZUMAYA ALGEBRAS, REFLEXIVE MODULES, AND PICARD NUMBERS FOR A FAMILY OF RATIONAL SURFACES TIMOTHY J by Azumaya algebras that are locally trivial. This implies that on X there are many reflexive modules that do, and n 2 an integer which divides m. Assume k contains m, a primitive mth root of unity. For distinct

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

    E-print Network

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

  19. 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

  20. 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

  1. Vestibulospinal control of reflex and voluntary head movement

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  2. 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.

  3. Constructing mock catalogues for the REFLEX II galaxy cluster sample

    E-print Network

    Balaguera-Antolínez, A; Böhringer, H; Collins, C

    2012-01-01

    We describe the construction of a suite of galaxy cluster mock catalogues from N-body simulations, based on the properties of the new ROSAT-ESO Flux-Limited X-Ray (REFLEX II) galaxy cluster catalogue. Our procedure is based on the measurements of the cluster abundance, and involves the calibration of the underlying scaling relation linking the mass of dark matter haloes to the cluster X-ray luminosity determined in the \\emph{ROSAT} energy band $0.1-2.4$ keV. In order to reproduce the observed abundance in the luminosity range probed by the REFLEX II X-ray luminosity function ($0.01

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

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

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

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

  11. 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

  12. MONOSYNAPTIC REFLEX RESPONSE OF SPINAL MOTONEURONS TO GRADED AFFERENT STIMULATION

    PubMed Central

    Hunt, Carlton C.

    1955-01-01

    Monosynaptic reflex response of spinal motoneurons to graded afferent volleys has been studied in natural populations and in a representative sample of individual motoneurons. By analysis of input-response relations certain of the requirements for initiation of reflex discharge have been defined. Initation of motoneuron discharge by monosynaptic afferent excitatory volleys results from the development of transmitter potentiality among members of a pool. Transmitter potentiality is considered to have the following characteristics: 1. It is a function of the number of active excitatory synaptic knobs, the degree to which such knobs are aggregated on the motoneuron soma, and the intensity of action per knob. 2. It has an appreciable spatial decrement and rapid temporal decay. 3. While transmitter potentiality has considerable dependence on number of active excitatory knobs, proximity of such knobs is an important variable. Total activation of a discrete zone does not appear to be necessary for initiation of discharge. In addition to initiation of discharge, volleys in monosynaptic afferent excitatory fibers facilitate response otherwise engendered. Such facilitation depends upon the production of an increment in transmitter potentiality. Facilitator potentiality has the following characteristics: 1. It depends principally on number of active excitatory synaptic knobs and intensity of action per knob. 2. Facilitatory action may result from synchronous activity in knobs interspersed among aggregations of knobs otherwise activated, thus fulfilling spatial requirements for transmitter potentiality. Alternatively a residual facilitation may result from a generalized action. 3. Residual facilitation has a slow temporal decay in comparison with transmitter potentiality. PMID:13242766

  13. In Vitro Analog of Classical Conditioning of Feeding Behavior in Aplysia

    E-print Network

    Byrne, John H.

    tactile stimulation of the lips as a conditioned stimulus (CS) and food as an unconditioned stimulus (US) and from studies that focused on simple defensive reflexes (e.g., Carew et al. 1981; Hawkins et al. 1983

  14. 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.

  15. 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

  16. What is a reflex? A guide for understanding disorders of consciousness.

    PubMed

    Fischer, David B; Truog, Robert D

    2015-08-11

    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

  17. Inhibition of spinal reflexes by acetylsalicylate and metamizol (dipyrone) in rats.

    PubMed

    Genç, O; Turgut, S; Turgut, G; Kortunay, S

    2003-11-01

    The effects of acetylsalicylate and metamizol on spinal monosynaptic reflexes were tested in spinal rats. Adult rats were anesthetized with ketamine, artificially ventilated, and spinalized at the C1 level. A laminectomy was performed in the lumbosacral region. Following electrical stimulation of the sciatic nerve by single pulses, the reflex potentials were recorded from the ipsilateral L5 ventral root. Acetylsalicylate was administered orally via nasogastric tube and metamizol intramuscularly. Acetylsalicylate (50 and 100 mg/kg) and metamizol (15 mg/kg) significantly decreased the amplitude of the reflex response (p < 0.05). But the 10-mg/kg metamizol dose did not significantly decrease the amplitude of the reflex response. The cyclooxygenase products of arachidonic acid may play an important role in regulating the reflex potential. PMID:14512697

  18. 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’ o?ine interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our o?ine 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

  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 ?M 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