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1

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

PubMed

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

Kim, O J

1992-01-01

2

Conditioning the middle ear reflex at sensation levels below reflex threshold: air jet and electrical stimulation.  

PubMed

An ABAB functional analysis, conditioning and generalization, design was used in 3 experiments (2 were formal studies and 1 was empirical in nature) to investigate the conditionability of the middle ear reflex. The conditioned stimuli were subreflex threshold pure tones of various frequencies and intensities. The unconditioned stimulus (UCS) was an auricular air jet to the contralateral ear in the first experiment and cutaneous electrical stimulation to the ipsolateral, probe ear in the last 2 experiments. Reflexes were monitored by an otoadmittance meter, storage oscilloscope, and strip chart recorder. In the first experiment (air jet UCS), no subjects met the conditioning criterion within the maximum presentation of 400 paired trials, despite pilot evidence which indicated conditioning was feasible. In the second experiment (electrical stimulation UCS), 2 subjects met conditioning criterion; however, only one subject reconditioned and demonstrated partial generalization to other conditioned stimuli. In the third experiment (electrical stimulation UCS), one of 3 subjects who had previously been unconditionable with the air jet UCS met conditioning and reconditioning criterion and demonstrated partial generalization. Results indicate that the middle ear reflex can be conditioned to be elicited by subreflex threshold pure tones, however, results are limited. PMID:7429033

McDaniel-Bacon, L; Fulton, R T; Laskowski, R P

1980-01-01

3

Associative Mechanosensory Conditioning of the Proboscis Extension Reflex in Honeybees  

ERIC Educational Resources Information Center

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…

Giurfa, Martin; Malun, Dagmar

2004-01-01

4

Habituation and conditioning of the human long latency stretch reflex  

Microsoft Academic Search

The effects of stretch repetition rate, prior warning stimuli and self administered stretch were examined on the size of the short and long latency components of the stretch reflex electromyographic EMG response in flexor pollicis longus and the flexor muscles of the wrist and fingers. Stretches of constant velocity and extent were given every 10 s, 5 s, 2 s,

J. C. Rothwell; B. L. Day; A. Berardelli; C. D. Marsden

1986-01-01

5

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

E-print Network

not generalize from air puff to electro- dermal stimulation even though conditioning occurs to comparable levels can be obtained only at high air puff intensi- ties even though conditioning is supported by lower airConditioning-specific reflex modification occurs when an unconditionedresponse

6

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

PubMed Central

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

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

2014-01-01

7

A CHANGE OF UNCONDITIONED AND CONDITIONED-REFLEX LIUKOCYTIC REACTIONS FOLLOWING X-RAY IRRADIATION  

Microsoft Academic Search

Experiments were staged on 6 dogs. A study was made of the ; unconditioned and conditioned-reflex leukocytic reactions, as well as of the ; background variations of the leukocyte count, prior to and after a single total x-; ray irradiation of the animals with the doses of 600, 50, and 3 r. During the ; first day after the irradiation,

Ulyanov

1962-01-01

8

Changes in the unconditioned and conditioned reflex leukocytic reactions following roentgen irradiation  

Microsoft Academic Search

Experiments were staged on 6 dogs. A study was made of the unconditioned and conditioned-reflex leukocytic reactions (with electrocutaneous reinforcement), as well as of the background variations of the leukocyte count prior to and after a single total x-ray irradiation of the animals with the doses of 600, 50 and 3 r. During the first day (hours) after the irradiation,

M. I. Ul'yanov; N. M. Zharikov

1963-01-01

9

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

PubMed

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

Makihara, Yukiko; Segal, Richard L; Wolpaw, Jonathan R; Thompson, Aiko K

2014-09-15

10

Comparative analysis of the persistence of a conditioned passive avoidance reflex in rats with different forms of inherited hypertension  

Microsoft Academic Search

The characteristics of anxiety behavior and reproduction of a conditioned passive avoidance reflex acquired in response to\\u000a a single combination with an unconditioned aversive stimulus were studied in NISAG rats with inherited stress-sensitive arterial\\u000a hypertension and spontaneously hypertensive SHR rats. SHR rats were characterized by hyperactive behavior, very low levels\\u000a of anxiety, and poor reproduction of the conditioned reflex as

L. V. Loskutova; N. I. Dubrovina; A. L. Markel’

2007-01-01

11

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

NASA Astrophysics Data System (ADS)

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.

El-Yamany, Nabil A.

2008-12-01

12

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...

13

Functional asymmetry of the frontal cortex and lateral hypothalamus of cats during an operant food-related conditioned reflex.  

PubMed

The extent of correlation and the latency of evoked potentials to sound, recorded bilaterally in the frontal cortex and lateral hypothalamus of cats, were studied at different stages of the acquisition of an operant food-related reflex and during sudden transfer to 30% food reinforcement. High correlation coefficients between the evoked responses of the cortex and hypothalamus with left-sided dominance were seen in conditions of high levels of food motivation at the beginning of each experiment and in conditions of the high-probability appearance of the acquired conditioned reflex throughout the rest of the experiment. Comparison of the peak latencies of the early positive (P55-80) components of evoked potentials on the right and left sides showed that shorter latent periods were seen in the cortex on the left side at all behavioral stages, while this occurred (on the left side) in the hypothalamus only when the conditioned reflex was unfixed, while after fixation of the reflex and provision of 30% reinforcement, shorter latent periods were seen on the right side. It is concluded that the high level of left-sided correlation of evoked potentials in the hypothalamus was associated with the motivational and motor components of purposive behavior and was not associated with the emotional tension of the animals provoked by the disruption of the food reinforcement stereotype. PMID:15526426

Vanetsian, G L; Pavlova, I V

2004-09-01

14

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

PubMed

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

Shelepin, Iu E; Krasil'nikov, N N

2003-06-01

15

The influence of dynamic stereotype conditioned food reflexes and neurotic condition on the cardiac rhythm against a background of normal and disturbed cardiac activity  

Microsoft Academic Search

Neurotic condition of the animal provokes changes of respiration and cardiac activity rhythm with the appearance of severe disturbances in the latter in the form of paroxysms of tachycardia. Against the background of strophanthin poisoning and marked derangement of the cardiac activity it is possible to preserve intact the dynamic stererotype of conditioned food reflexes in dogs with a strong

A. Y. Alymov

1961-01-01

16

Inactivation of the central nucleus of the amygdala blocks classical conditioning but not conditioning-specific reflex modification of rabbit heart rate  

PubMed Central

Heart rate (HR) conditioning in rabbits is a widely used model of classical conditioning of autonomic responding that is noted for being similar to the development of conditioned heart rate slowing (bradycardia) in humans. We have shown previously that in addition to HR changes to a tone conditioned stimulus (CS), the HR reflex itself can undergo associative change called conditioning-specific reflex modification (CRM) that manifests when tested in the absence of the CS. Because CRM resembles the conditioned bradycardic response to the CS, we sought to determine if HR conditioning and CRM share a common neural substrate. The central nucleus of the amygdala (CeA) is a critical part of the pathway through which conditioned bradycardia is established. To test whether the CeA is also involved in the acquisition and/or expression of CRM, we inactivated the CeA with muscimol during HR conditioning or CRM testing. CeA inactivation blocked HR conditioning without completely preventing CRM acquisition or expression. These results suggest that the CeA may therefore only play a modulatory role in CRM. Theories on the biological significance of conditioned bradycardia suggest that it may represent a state of hypervigilance that facilitates the detection of new and changing contingencies in the environment. We relate these ideas to our results and discuss how they may be relevant to the hypersensitivity observed in fear conditioning disorders like post-traumatic stress. PMID:23266790

Burhans, Lauren B.; Schreurs, Bernard G.

2013-01-01

17

Effects of conditioning cutaneomuscular stimulation on the soleus H-reflex in normal and spastic paretic subjects during walking and standing.  

PubMed

1. The modulation of the soleus H-reflex by a conditioning cutaneomuscular stimulation was investigated in 10 normal and 10 spastic paretic subjects who suffered from incomplete spinal cord lesions. The different motor tasks examined were standing, locomotion, and the maintenance of static limb postures to mimic critical gait events. The test soleus H-reflex was obtained by stimulating the tibial nerve in the popliteal fossa with a single 1-ms pulse at an intensity that produced a barely detectable M wave. The conditioning stimulus, consisting of an 11-ms train of three 1-ms pulses at 200 Hz, was delivered to the ipsilateral medial plantar arch, stimulating predominantly the medial plantar nerve, at an innocuous intensity of 2.5-3.0 X sensory threshold and at a conditioning-test delay of 45 ms. 2. During quiet standing, the H-reflex amplitude was inhibited only marginally by the conditioning cutaneomuscular stimulation, not reaching statistical significance in either the normal or spastic group of subjects. Although there was a trend of reflex inhibition in the normal subjects as the conditioning intensity was increased, a reversed trend of reflex facilitation was observed in the spastic patients. 3. During treadmill walking, the conditioned H-reflex was inhibited significantly during all phases in all the normal subjects and in one mildly impaired patient. In the moderately and severely impaired patients, cutaneomuscular stimulation selectively inhibited the soleus H-reflex in the early stance and swing phases, thereby producing a near normal phasic modulation pattern. Such modulatory effects were not present under static gait-mimicking conditions. 4. The task-specific and phase-dependent effects of cutaneomuscular stimulation on the soleus H-reflex in the spinal cord-injured patients revealed strong inhibitory influence on Ia afferents from cutaneomuscular inputs. It is plausible that inhibition occurs at both pre- and postsynaptic levels. 5. It is concluded that normal Ia modulatory mechanisms during locomotion are deficient in spastic spinal cord-injured patients and can partially and artificially be restored by cutaneomuscular stimulation applied to the sole of the foot. This can be used as a functional electrical stimulation (FES) regime in gait rehabilitation. PMID:7884446

Fung, J; Barbeau, H

1994-11-01

18

Infant reflexes  

MedlinePLUS

... and the baby’s body is rotated quickly to face forward (as in falling). The baby will extend his arms forward as if to break a fall, even though this reflex appears long before the baby walks. Examples of ...

19

Fear conditioning of SCR but not the startle reflex requires conscious discrimination of threat and safety  

PubMed Central

There is conflicting evidence as to whether awareness is required for conditioning of the skin conductance response (SCR). Recently, Schultz and Helmstetter (2010) reported SCR conditioning in contingency unaware participants by using difficult to discriminate stimuli. These findings are in stark contrast with other observations in human fear conditioning research, showing that SCR predominantly reflects contingency learning. Therefore, we repeated the study by Schultz and Helmstetter and additionally measured conditioning of the startle response, which seems to be less sensitive to declarative knowledge than SCR. While we solely observed SCR conditioning in participants who reported awareness of the contingencies (n = 16) and not in the unaware participants (n = 18), we observed startle conditioning irrespective of awareness. We conclude that SCR but not startle conditioning depends on conscious discriminative fear learning. PMID:24616672

Sevenster, Dieuwke; Beckers, Tom; Kindt, Merel

2014-01-01

20

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

SciTech Connect

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.

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

2008-01-01

21

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

PubMed Central

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

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

2014-01-01

22

[Extinction of the defensive conditioned reflex in cats after lesioning the endopeduncularis nucleus].  

PubMed

Influence of bilateral destruction of nucleus entopeduncularis on the extinction of conditioned avoidance was studied in 10 adult cats. It was shown that bilateral destruction of the nucleus entopeduncularis led to a disturbance of storage of the previous conditioning and facilitated repeated extinction. PMID:11764525

Sarkisov, T T; Karapetian, L M; Sarkisian, Zh S; Mikaelian, Kh M

2001-01-01

23

Galvanic skin response-orienting reflex and semantic conditioning and generalization with different unconditioned stimuli  

Microsoft Academic Search

280 college students served in a semantic conditioning and generalization experiment where GSR and cephalic vasomotor response measures were obtained as well as semantic differential (SD) ratings of the control words and the critical CS and generalization test words. Different groups of Ss received either 110-db white noise, 95-db white noise, 80-db white noise, 110-db tone, or an 80-db tone

Irving Maltzman; Barry Langdon; Mary Pendery; Craig Wolff

1977-01-01

24

Involvement of protein synthesis in the reconsolidation of memory at different time points after formation of conditioned reflex freezing in mice  

Microsoft Academic Search

The aim of the present work was to study the involvement of protein synthesis in the reconsolidation of memory at different\\u000a periods of time after training. In mice trained in a conditioned reflex freezing model, memory was reactivated by a reminder\\u000a combined with administration of the protein synthesis inhibitor cycloheximide. The results showed that suppression of protein\\u000a synthesis on reactivation

E. V. Murav’eva; K. V. Anokhin

2007-01-01

25

Experimenting With Baroreceptor Reflexes  

NASA Technical Reports Server (NTRS)

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.

Eckberg, Dwain L.; Goble, Ross L.

1988-01-01

26

The inhibitory control reflex.  

PubMed

Response inhibition is typically considered a hallmark of deliberate executive control. In this article, we review work showing that response inhibition can also become a 'prepared reflex', readily triggered by information in the environment, or after sufficient training, or a 'learned reflex' triggered by the retrieval of previously acquired associations between stimuli and stopping. We present new results indicating that people can learn various associations, which influence performance in different ways. To account for previous findings and our new results, we present a novel architecture that integrates theories of associative learning, Pavlovian conditioning, and executive response inhibition. Finally, we discuss why this work is also relevant for the study of 'intentional inhibition'. PMID:25149820

Verbruggen, Frederick; Best, Maisy; Bowditch, William A; Stevens, Tobias; McLaren, Ian P L

2014-12-01

27

Vestibular-Ocular Reflex  

NSDL National Science Digital Library

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

Marlene Y. Macleish, Ed D.; Bernice R. Mclean, M. E.

2013-01-30

28

[Analysis of changes in the electrical activity of the neocortex in dogs during the formation of the stereotype of food-procuring conditioned reflexes in them].  

PubMed

A system of food-procuring conditioned reflexes (dynamic stereotype after I.P. Pavlov) was elaborated in dogs. In the interstimuli periods, 0.6 to 0.8 sec. prior the action of the conditioned stimulus, they exhibited a "state of expectancy" characterized by an increase of frequency (up to 80 per sec.) of potential oscillations of a small amplitude (20 to 30 mcv) and their pronounced sychroneity, predominantly in the anterior parts of the neocortex. The conditioned signal acting against such background produced specific reactions in the form of a limited number of bursts (3 to 4 in 0.5 sec.) of highfrequency (up to 100 per sec.) synchronized activity (HSA) of considerable amplitude (50 to 60 mcv) which always preceded conditioned reactions, being in certain temporal relations with them. A correlation-spectral analysis has shown that in the HSA period, electrical activity became considerably more regular; in the intensity spectra the extreme frequencies of the analyzed band (5 to 7 c/s and 90 to 100 c/s) became prominent, and in most cases high values of the coherence function were due to them. HSA reactions are regarded as a major link in the trigger mechanism of conditioned food-procuring reactions. PMID:563650

Dumenko, V N

1977-01-01

29

Reflexive ideals in Iwasawa algebras  

Microsoft Academic Search

Let G be a torsionfree compact p-adic analytic group. We give sufficient conditions on p and G which ensure that the Iwasawa algebra ?G of G has no non-trivial two-sided reflexive ideals. Consequently, these conditions imply that every non-zero normal element in ?G is a unit. We show that these conditions hold in the case when G is an open

Konstantin Ardakov; Feng Wei; James J. Zhang

2008-01-01

30

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

ERIC Educational Resources Information Center

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)

Pendery, Mary; Maltzman, Irving

1977-01-01

31

Astronomical Data Reduction Workflows with Reflex  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

32

Reflecting on Human Reflexes  

NSDL National Science Digital Library

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

GK-12 Program, Computational Neurobiology Center,

33

Effect of 2-amino-5-phosphopentanoic acid (AP5), a glutamate NMDA receptor blocker, on neuron activity in the cat motor cortex during performance of a paw placement conditioned reflex  

Microsoft Academic Search

Two types of stimulus-associated response were recorded in the contralateral motor cortex during performance of a condition\\u000a reflex consisting of placing the forepaw on a support in response to a short electrical stimulus (4 msec, 500 Hz) applied\\u000a to the contralateral parietal cortex (field 5). Primary shortlatency responses (peak latent period about 10 msec, duration\\u000a 30–50 msec) showed little sensitivity

V. I. Maiorov; B. V. Chernyshev; A. A. Moskvitin

1998-01-01

34

Evidence for reflex and perceptual vestibular contributions to postural control  

Microsoft Academic Search

Vestibular signals are known to have an important role in stance under specific conditions. Potentially these effects could be modulated by vestibular reflexes or by voluntary responses to perceived vestibular signals. Our preliminary aim was to confirm that vestibulospinal reflexes change in parallel with sway under different postural conditions, and then to determine whether any relationship was present between these

Ann M. Bacsi; James G. Colebatch

2005-01-01

35

On Reflexive Data Models  

SciTech Connect

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.

Petrov, S.

2000-08-20

36

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

E-print Network

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 ...

Backus, Bradford Clark

2005-01-01

37

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

PubMed

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

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

2012-06-01

38

Reflex: Graphical workflow engine for data reduction  

NASA Astrophysics Data System (ADS)

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

ESO Reflex development Team

2014-01-01

39

Cockcrow reflex epilepsy  

Microsoft Academic Search

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

Agostino Nappo

1995-01-01

40

Reflexivity in pigeons.  

PubMed

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

Sweeney, Mary M; Urcuioli, Peter J

2010-11-01

41

The oculorespiratory reflex revisited  

Microsoft Academic Search

Continuous measurement of the intratracheal pressure and capnography are very simple and accessible methods for the detection\\u000a and recording of the oculorespiratory reflex (ORR). Eight healthy children (five to 14 years old) undergoing strabismus surgery\\u000a under halothane-nitrous oxide anaesthesia with spontaneous ventilation were studied. The ORR was evoked by traction on the\\u000a extrinsic muscles of the eye (four medial recti

Victor Faria Blanc; Jean-Louis Jacob; Jean Milot; Louise Cyrenne

1988-01-01

42

Baroreceptor Reflex Role Play  

NSDL National Science Digital Library

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

Marlene Y. MacLeish

2012-06-26

43

Demand functions and reflexivity  

NASA Astrophysics Data System (ADS)

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

Polyrakis, Ioannis A.

2008-02-01

44

Modification of cutaneous reflexes during visually guided walking.  

PubMed

Although it has become apparent that cutaneous reflexes can be adjusted based on the phase and context of the locomotor task, it is not clear to what extent these reflexes are regulated when locomotion is modified under visual guidance. To address this, we compared the amplitude of cutaneous reflexes while subjects performed walking tasks that required precise foot placement. In one experiment, subjects walked overground and across a horizontal ladder with narrow raised rungs. In another experiment, subjects walked and stepped onto a series of flat targets, which required different levels of precision (large vs. narrow targets). The superficial peroneal or tibial nerve was electrically stimulated in multiple phases of the gait cycle in each condition and experiment. Reflexes between 50 and 120 ms poststimulation were sorted into 10 equal phase bins, and the amplitudes were then averaged. In each experiment, differences in cutaneous reflexes between conditions occurred predominantly during swing phase when preparation for precise foot placement was necessary. For instance, large excitatory cutaneous reflexes in ipsilateral tibialis anterior were present in the ladder condition and when stepping on narrow targets compared with inhibitory responses in the other conditions, regardless of the nerve stimulated. In the ladder experiments, additional effects of walking condition were evident during stance phase when subjects had to balance on the narrow ladder rungs and may be related to threat and/or the unstable foot-surface interaction. Taken together, these results suggest that cutaneous reflexes are modified when visual feedback regarding the terrain is critical for successful walking. PMID:24155011

Ruff, Casey R; Miller, Andreas B; Delva, Mona L; Lajoie, Kim; Marigold, Daniel S

2014-01-01

45

Peroneus longus stretch reflex amplitude increases after ankle brace application  

PubMed Central

Background: The use of external ankle support is widespread throughout sports medicine. However, the application of ankle bracing to a healthy ankle over a long period has been scrutinised because of possible neuromuscular adaptations resulting in diminished dynamic support offered by the peroneus longus. Objective: To investigate the immediate and chronic effects of ankle brace application on the amplitude of peroneus longus stretch reflex. Methods: Twenty physically active college students (mean (SD) age 23.6 (1.7) years, height 168.7 (8.4) cm, and mass 69.9 (12.0) kg) who had been free from lower extremity pathology for the 12 months preceding the study served as subjects. None had been involved in a strength training or conditioning programme in the six months preceding the study. A 3 x 3 x 2 (test condition x treatment condition x time) design with repeated measures on the first and third factor was used. The peroneus longus stretch reflex (% of maximum amplitude) during sudden foot inversion was evaluated under three ankle brace conditions (control, lace up, and semi-rigid) before and after eight weeks of ankle brace use. Results: A 3 x 3 x 2 repeated measures analysis of variance showed that peroneus longus stretch reflex amplitude increased immediately after application of a lace up brace (67.1 (4.4)) compared with the semi-rigid (57.9 (4.3)) and control (59.0 (5.2)) conditions (p<0.05). Peroneus longus stretch reflex also increased after eight weeks of use of the semi-rigid brace compared with the lace up and control conditions (p<0.05). Conclusions: Initial application of a lace up style ankle brace and chronic use of a semi-rigid brace facilitates the amplitude of the peroneus longus stretch reflex. It appears that initial and long term ankle brace use does not diminish the magnitude of this stretch reflex in the healthy ankle. PMID:12782553

Cordova, M; Ingersoll, C

2003-01-01

46

The influence of stretching and warm?up exercises on Achilles tendon reflex activity  

Microsoft Academic Search

The aim of this study was to investigate the acute effects of prior exercise (warm?up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min)

Dieter Rosenbaum; Ewald M. Hennig

1995-01-01

47

Dysphoric milk ejection reflex: A case report  

PubMed Central

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

2011-01-01

48

Avian reflex and electroencephalogram responses in different states of consciousness.  

PubMed

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

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

2014-06-22

49

Flexor reflex decreases during sympathetic stimulation in chronic human spinal cord injury.  

PubMed

A better understanding of autonomic influence on motor reflex pathways in spinal cord injury is important to the clinical management of autonomic dysreflexia and spasticity in spinal cord injured patients. The purpose of this study was to examine the modulation of flexor reflex windup during episodes of induced sympathetic activity in chronic human spinal cord injury (SCI). We simultaneously measured peripheral vascular conductance and the windup of the flexor reflex in response to conditioning stimuli of electrocutaneous stimulation to the opposite leg and bladder percussion. Flexor reflexes were quantified using torque measurements of the response to a noxious electrical stimulus applied to the skin of the medial arch of the foot. Both bladder percussion and skin conditioning stimuli produced a reduction (43-67%) in the ankle and hip flexor torques (p<0.05) of the flexor reflex. This reduction was accompanied by a simultaneous reduction in vascular conductance, measured using venous plethysmography, with a time course that matched the flexor reflex depression. While there was an overall attenuation of the flexor reflex, windup of the flexor reflex to repeated stimuli was maintained during periods of increased sympathetic activity. This paradoxical depression of flexor reflexes and minimal effect on windup is consistent with inhibition of afferent feedback within the superficial dorsal horn. The results of this study bring attention to the possible interaction of motor and sympathetic reflexes in SCI above and below the T5 spinal level, and have implications for clinicians in spasticity management and for researchers investigating motor reflexes post SCI. PMID:19615998

Garrison, M Kevin; Schmit, Brian D

2009-10-01

50

Effect of cervicolabyrinthine impulsation on the spinal reflex apparatus  

NASA Technical Reports Server (NTRS)

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.

Yarotskiy, A. I.

1980-01-01

51

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

PubMed

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

Gibson, W; Campbell, A; Allison, G

2013-09-01

52

Stretch reflexes of triceps surae in normal man  

Microsoft Academic Search

In order to learn more about stretch reflex behaviour of triceps surae, normal human subjects sat in a chair with one foot on a platform attached to a torque motor that produced phasic dorsiflexion displacements on the ankle. EMG activity was recorded from triceps surae and responses were obtained for various conditions. When the subjects's foot was relaxed, stretch of

A Berardelli; M Hallett; C Kaufman; E Fine; W Berenberg; S R Simon

1982-01-01

53

Pupil Light Reflex Produced by Glare under Mesopic Adaptation  

Microsoft Academic Search

The amount of light captured by the eye depends on pupil size. Moreover, one of the factors determining the steady-state pupil size is ambient illumination and sudden increments of light reaching the retina cause a brisk and transient pupil constriction described as the dynamic Pupil Light Reflex response. In experiments where a glare source acts as transient conditioning field, a

Elisa Colombo; Silvia Ana Comastri; Luis Issolio; Rodolfo Echarri

2007-01-01

54

Adaptation of reflexive feedback during arm posture to different environments.  

PubMed

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

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

2002-07-01

55

Pneumatic Registration of Vestibulospinal Reflexes  

Microsoft Academic Search

Vestibulospinal reflexes were studied by measuring the laterotorsion of the head spontaneously and after the bithermal caloric tests. Measurement was made in the supine position by comparing the pressure on two pneumatic balloons placed one on each side of the occiput. The variation in pressure was measured by a water manometer. Evaluation of the results measured by various parameters would

M. Spector

1970-01-01

56

Vestibulocollic reflexes in the absence of head postural control.  

PubMed

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

Forbes, Patrick A; Siegmund, Gunter P; Happee, Riender; Schouten, Alfred C; Blouin, Jean-Sébastien

2014-10-01

57

Vestibular-ocular accommodation reflex in man  

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

58

The oculocardiag reflex during strabismus surgery  

Microsoft Academic Search

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

George T Moonie; Donald L Rees; Denzil Elton

1964-01-01

59

Generalized versus partial reflex seizures: a review.  

PubMed

In this review we assess our currently available knowledge about reflex seizures with special emphasis on the difference between "generalized" reflex seizures induced by visual stimuli, thinking, praxis and language tasks, and "focal" seizures induced by startle, eating, music, hot water, somatosensory stimuli and orgasm. We discuss in particular evidence from animal, clinical, neurophysiological and neuroimaging studies supporting the concept that "generalized" reflex seizures, usually occurring in the setting of IGE, should be considered as focal seizures with quick secondary generalization. We also review recent advances in genetic and therapeutic approach of reflex seizures. PMID:24766826

Italiano, Domenico; Ferlazzo, Edoardo; Gasparini, Sara; Spina, Edoardo; Mondello, Stefania; Labate, Angelo; Gambardella, Antonio; Aguglia, Umberto

2014-08-01

60

Changes in recurrent inhibition during voluntary soleus contractions in man studied by an H-reflex technique.  

PubMed Central

1. The recurrent inhibition, brought about by a conditioning H-reflex discharge, was estimated in human subjects by the amplitude of a test H-reflex involving only the soleus motoneurones which fired in response to the conditioning volley. The modifications of the recurrent inhibition during contraction were evaluated by comparing the amplitude of the test H-reflex to a reference H-reflex. Both reflexes experienced the excitation underlying the voluntary contraction, but only the test H-reflex was subjected to the recurrent inhibition evoked by the conditioning H-reflex discharge. 2. Distinct differences were observed between the modifications of the test reflex and those of the reference H-reflex during both tonic and phasic voluntary contractions. Evidence is presented that these differences were due to changes in the amount of recurrent inhibition elicited by the conditioning discharge. 3. The changes in recurrent inhibition were studied while the subjects performed voluntary tonic contractions of various forces. The weakest contractions were accompanied by a decrease in the size of the test reflex. With greater contraction forces, there was no longer an inhibition of the test reflex, but instead a facilitation which grew continuously with increased contraction forces. The test reflex could eventually exceed the reference H-reflex amplitude at the strongest contractions. This is taken to indicate that the recurrent inhibition following the conditioning discharge was progressively decreasing, as the contraction force increased. 4. During ramp contractions, whatever the contraction velocity, the time courses of the variations of the test and reference H reflexes were almost inverse. Evidence is presented that these differential time courses were due to changes in the amount of recurrent inhibition elicited by the conditioning discharge. 5. The possibility of occlusion in the recurrent pathway ;as considered and it was concluded that the decrease in the recurrent inhibition elicited by the conditioning discharge was essentially due to an inhibitory control (spinal and/or suprasegmental) acting on Renshaw cells. This inhibition of Renshaw cells eventually counteracts the increasing excitatory inputs (resulting from the voluntary motor discharge) which they receive via motor axon collaterals during increasing tonic contractions and throughout ramp contractions. 6. The functional significance of the Renshaw cell inhibition during voluntary contraction is discussed in relation to the inhibition exerted through the recurrent pathway on both motoneurones and Ia inhibitory interneurones. It is suggested that the depression of Renshaw cell activity could play an important role during voluntary movements by favouring reciprocal Ia inhibition. PMID:536912

Hultborn, H; Pierrot-Deseilligny, E

1979-01-01

61

21 CFR 890.1450 - Powered reflex hammer.  

...2014-04-01 2014-04-01 false Powered reflex hammer. 890.1450 Section 890...Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device...

2014-04-01

62

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Powered reflex hammer. 890.1450 Section 890...Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device...

2012-04-01

63

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Powered reflex hammer. 890.1450 Section 890...Medicine Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device...

2013-04-01

64

[The facilitation and inhibition of monosynaptic reflexes in the upper extremity of nursing infants].  

PubMed

The upper extremity H-reflex was investigated in healthy children, aged from 3 to 15 months. The electromyographic reflex responses of m. abduct or digiti min. and m. flexor carpi uln. were registered after electric stimulation of n. ulnaris. We constructed the curve of restoration of H-reflex after application of a couple of stimuli with equal duration and intensity, but over increasing intervals. We established changes in the excitation of H-reflex, obtained from m. flexor carpi uln., by increasing of the interval between the conditional and test stimuli. In the interval of 5 ms maximal facilitation was registered, while in the interval of 20 and 30 ms-maximal inhibition. In children aged from 3 to 9 months with persisting H-reflex in m. abductor digit min. we established possibility for its complete inhibition after application of a couple of stimuli with interval of 20 ms. In children aged from 9 to 15 months with vanished H-reflex in m. abductor digiti min. possibility for its obtaining was established after application of a couple of stimuli with interval of 5 ms. Quotation is made of evidences in favour of the hypothesis for the functional character of the disappearance of H-reflex in the small muscles of the arm in the first year of life of the children. PMID:8258317

Gatev, V; Angelova, B; Litvinenko, I

1993-01-01

65

Effect of nucleus raphe magnus stimulation on recurrent inhibition of the monosynaptic reflex in the cat.  

PubMed

Experiments were performed on 8 cats anesthetized with urethan-chloralose. The effects of nucleus raphe magnus (NRM) conditioning stimulation on recurrent inhibition of posterior biceps semitendinosus nerve (PBSt) monosynaptic reflex elicited by electric stimulation of a part of L7 ventral root were investigated in the cat. It was found that (1) the PBSt monosynaptic reflex was facilitated by NRM conditioning stimulation at 30, 50 and 80 ms conditioning-test stimulus intervals, but that (2) the inhibited monosynaptic reflex by recurrent inhibition was further inhibited by NRM conditioning stimulation at the same conditioning-test stimulus intervals, and that (3) the activity of Renshaw cells as recorded by glass microelectrode was enhanced by NRM conditioning stimulation. These facts indicated that recurrent inhibition pathways are enhanced by NRM conditioning stimulation. PMID:2616052

Wada, N; Yawashima, Y; Nakajima, Y

1989-12-15

66

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

E-print Network

apparently avoided. In such cases, however, it is simply submerged. The deconstructive technique employed by Derrida indicates that reflexive paradoxes can be found in any text, so long as they are examined closely...While reflexivity cannot be avoided... 7 perspectival fixity, no universal fixity. With Nietzsche, the dichotomies presented by reason is foundational or essential are undermined. They arc no longer necessary conditions. Imagination and creativity come to replace the rationalist...

Pickard, Dean

67

Reflexive autoepistemic logic and logic programming  

E-print Network

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 modal formalism for studying properties of answer sets for logic programs with classical negation

Marek, Victor W.

68

Photorealistic models for pupil light reflex and iridal pattern deformation  

Microsoft Academic Search

We introduce a physiologically-based model for pupil light reflex (PLR) and an image-based model for iridal pattern deformation. Our PLR model expresses the pupil diameter as a function of the lighting of the environment, and is described by a delay-differential equation, naturally adapting the pupil diameter even to abrupt changes in light conditions. Since the parameters of our PLR model

Vitor F. Pamplona; Manuel M. Oliveira; Gladimir V. G. Baranoski

2009-01-01

69

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

PubMed

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

Hoogkamer, Wouter; Van Calenbergh, Frank; Swinnen, Stephan P; Duysens, Jacques

2015-02-01

70

Human flexor reflex modulation during cycling.  

PubMed

1. Human flexor reflex (HFR) responses were elicited during ergometer cycling in neurologically intact humans with the objective of understanding the influence of lower limb muscle activity on phase-dependent reflex modulation during movement. The experimental setup permitted control over background muscle activity and stimulus intensity without significantly interfering with the cycling motion. 2. All experiments involved cycling on an ergometer at a set rate and workload. A 333-Hz, 15-ms pulse train of electrical stimulation was randomly delivered to the skin over the tibial nerve at the ankle at selected lower limb positions. In the first group of experiments, subjects were stimulated at six cycling phases while pedaling with normal, phasic ankle activity (free-form cycling). The second and third group of experiments involved stimulation under static limb positioning conditions and during active pedaling while subjects were asked to maintain a consistent background level of isolated tibialis anterior (TA) or soleus (SOL) electromyographic (EMG) activity. 3. Control criteria were established to assure similar isolated muscle EMG levels and sensory stimulation intensities throughout the experiments. With the aid of the application of a lower extremity brace and visual EMG feedback, SOL and TA activity were confined by the subject to a narrow range during the task of cycling. Stimulus consistency was achieved through maintenance of flexor hallucis brevis M-waves to within an envelope encompassing the mean value +/- 5% of the maximum M-wave amplitude in all experimental conditions. 4. When the subject's limb was statically positioned, the HFR responses in the SOL muscle showed no significant changes in pattern when compared at various limb positions. During cycling with consistent SOL activity, a response waveform pattern of early-latency-long-duration depression was followed by a later-latency facilitation response in all positions except the initial power phase. The initial power phase was characterized by an additional early-latency facilitation in all but one subject. 5. In the TA muscle response, no change in onset latency (57.5 +/- 0.8 ms, mean +/- SD), waveform pattern, or response amplitude (7.9 +/- 1.1% maximal voluntary contraction, mean +/- SD) was observed during static limb positioning. Significant increases in response amplitude (P < 0.05) coupled with significant increases (9.2 ms, P < 0.05) in onset latency were seen during the transition from the recovery phase to the power phase during cycling. In addition, there was no correlation between the prestimulation baseline level and the onset latency during controlled TA cycling activity conditions.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8492160

Brown, D A; Kukulka, C G

1993-04-01

71

Achilles tendon reflex measuring system  

NASA Astrophysics Data System (ADS)

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

Szebeszczyk, Janina; Straszecka, Joanna

1995-06-01

72

Abnormal oculocardiac reflex in two patients with Marcus Gunn syndrome.  

PubMed

Marcus Gunn phenomenon is seen in 4 to 6% of congenital ptosis patients. We report two cases of abnormal oculocardiac reflex during ptosis correction surgery. Marcus Gunn syndrome is an autosomal dominant condition with incomplete penetrance. It is believed to be a neural misdirection syndrome in which fibres of the motor division of the trigeminal nerve are congenitally misdirected into the superior pterygoid and the levator muscles. Anesthetic considerations include taking a detailed history about any previous anaesthetic exposure and any reaction to it as this syndrome has a high probability of being associated with malignant hyperthermia. It is also postulated that an atypical oculocardiac reflex might be initiated in these patients as seen in our patients, so precautions must be taken for its prevention and early detection. PMID:21897519

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

2011-07-01

73

Reflexive fighting in response to aversive stimulation1  

PubMed Central

Reflexive fighting was elicited between paired rats as a reflex reaction to electric shock prior to any specific conditioning. Such fighting was fairly stereotyped and easily differentiated from the rats' usual behavior. The strength of this reflex was not attributable to any apparent operant reinforcement. Elicitation of fighting was a direct function of the enclosed floor area and a nonmonotonic function of the shock intensity. Failure to scramble the polarity of the electrified grid produced inconsistent fighting. Under optimal conditions fighting was consistently elicited by shock regardless of the rat's sex, strain, previous familiarity with each other, or the number present during shock. Repeated shock presentations did not produce an appreciable decrease in fighting until signs of physical debility appeared. Although shock did not cause a rat to attack inanimate objects, it did produce attack movements toward other small animals. Failure of guinea pigs to defend themselves revealed that the elicitation of fighting from the rat does not require reciprocal attack. Paired hamsters showed fighting reactions similar to those of the rats, whereas guinea pigs failed to fight. Electrode shock and a heated floor elicited fighting between the rats, but intense noise and a cooled floor did not. ImagesFig. 1. PMID:13995319

Ulrich, R. E.; Azrin, N. H.

1962-01-01

74

Changes in the Achilles tendon reflexes following Skylab missions  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

75

Brainstem and spinal reflex studies in patients with primary progressive freezing of gait.  

PubMed

Our aim was to investigate the extent and pattern of involved pathways using brainstem and spinal reflexes by comparing primary progressive freezing of gait (PPFOG) progressive supranuclear palsy (PSP) with FOG. Seven patients with PPFOG and age and sex matched seven PSP patients and 16 healthy subjects were included in the study. All subjects underwent blink reflex (BR), trigemino-cervical reflex (TCR), auditory startle reflex (ASR) and long latency flexor reflex (LLFR) investigations under the same conditions. All three groups had normal BR latencies. ASR probability was lowest in the PSP group and was highest in PPFOG (p=0.005). The presence rate of TCR was lowest in PSP and it was highest in PPFOG (p=0.007 for SC and p=0.023 for SCM). The presence rate and amplitude of LLFR (R II) were decreased in the PSP group (p=0.010 and p=0.031, respectively) whereas it was in a continuous pattern in some of PPFOG patients. ASR, TCR and LLFR were all inhibited in PSP and we suggest that suppression of all three reflexes is probably related to degeneration of brainstem reticular formation and basal ganglia connections. However, interestingly, in PPFOG, excitabilities of ASR and TCR circuits are increased suggesting loss of pathways mediating suprasegmental control. PMID:24867166

K?z?ltan, Meral E; Gunduz, Aysegul; K?z?ltan, Gunes; Tekeo?lu, An?l; Sohtao?lu, Melis

2014-08-15

76

Reflexivity and the capacity to think.  

PubMed

Reflexivity is fundamental to qualitative health research, yet notoriously difficult to unpack. Drawing on Wilfred Bion's work on the development of the capacity to think and to learn, I show how the capacity to think is an impermanent and fallible capacity, with the potential to materialize or evaporate at any number of different points. I use this conceptualization together with examples from published interview data to illustrate the difficulties for researchers attempting to sustain a reflexive approach, and to direct attention toward the possibilities for recovering and supporting the capacity to think. I counter some of the criticisms suggesting that reflexivity can be self-indulgent, and suggest instead that self-indulgence constitutes a failure of reflexivity. In the concluding discussions I acknowledge tensions accompanying the use of psychoanalytic theories for research purposes, and point to emerging psychosocial approaches as one way of negotiating these. PMID:23258421

Doyle, Sarah

2013-02-01

77

Variability in Hoffmann and tendon reflexes in healthy male subjects  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

78

Reflex ring laser amplifier system  

DOEpatents

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.

Summers, M.A.

1983-08-31

79

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

PubMed

Adaptation of reflexes to environment and task at hand is a key mechanism in optimal motor control, possibly regulated by the cortex. In order to locate the corticospinal integration, i.e. spinal or supraspinal, and to study the critical temporal window of reflex adaptation, we combined transcranial magnetic stimulation (TMS) and upper extremity muscle stretch reflexes at high temporal precision. In twelve participants (age 49±13 years, eight male), afferent signals were evoked by 40ms ramp and subsequent hold stretches of the m. flexor carpi radialis (FCR). Motor conduction delays (TMS time of arrival at the muscle) and TMS-motor threshold were individually assessed. Subsequently TMS pulses at 96% of active motor threshold were applied with a resolution of 5-10ms between 10ms before and 120ms after onset of series of FCR stretches. Controlled for the individually assessed motor conduction delay, subthreshold TMS was found to significantly augment EMG responses between 60 and 90ms after stretch onset. This sensitive temporal window suggests a cortical integration consistent with a long latency reflex period rather than a spinal integration consistent with a short latency reflex period. The potential cortical role in reflex adaptation extends over the full long latency reflex period, suggesting adaptive mechanisms beyond reflex onset. PMID:25449867

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

2015-01-01

80

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

81

Using ESO Reflex with Web Services  

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

82

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

PubMed

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

Grogan, Aaron D

2014-08-01

83

Biological motion cues trigger reflexive attentional orienting  

PubMed Central

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 was significantly better on a target in the walking direction compared with that in the opposite direction even when participants were explicitly told that walking direction was not predictive of target location. Interestingly, the effect disappeared when the walker was shown upside-down. Moreover, the reflexive attentional orienting could be extended to motions of other biological entities but not inanimate objects, and was not due to the viewpoint effect of the point-light figure. Our findings provide strong evidence that biological motion cues can trigger reflexive attentional orienting, and highlight the intrinsic sensitivity of the human visual attention system to biological signals. PMID:20883983

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

2010-01-01

84

Nasal reflexes: Implications for exercise, breathing, and sex  

Microsoft Academic Search

Nasal patency, with both congestion and decongestion, is affected in a wide variety of reflexes. Stimuli leading to nasal\\u000a reflexes include exercise; alterations of body position, pressure, and temperature; neurologic syndromes; and dentistry. As\\u000a anticipated, the vagal and trigeminal systems are closely integrated through nasobronchial and bronchonasal reflexes. However,\\u000a perhaps of greater pathophysiologic importance are the naso-hypopharyn-geal-laryngeal reflexes that become

James N. Baraniuk; Samantha J. Merck

2008-01-01

85

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

E-print Network

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 orbit-reflexive. In particular, every Banach space operator with spectral radius different from 1 is orbit-reflexive. Better estimates are obtained

Müller, Vladimír

86

Reflex vertical gaze and the medial longitudinal fasciculus  

Microsoft Academic Search

Extraocular movements were investigated in a patient with bilateral vascular lesions of the medial longitudinal fasciculus. The patient showed voluntary and reflex horizontal gaze consistent with his lesion, but had absent reflex vertical gaze. Voluntary vertical gaze was present. Necropsy was performed, and the findings suggest that the medial longitudinal fasciculi in the pons conveys impulses for reflex vertical gaze,

L. R. Jenkyn; G. Margolis; A. G. Reeves

1978-01-01

87

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

PubMed

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

Berkowitz, Murray R

2015-01-01

88

Communicating Science: Exploring Reflexive Pedagogical Approaches  

ERIC Educational Resources Information Center

This paper considers the value of reflexive pedagogical approaches in the teaching of academic communication and writing. We focus on a course developed for pre-degree foundation students at a London higher education institution. Drawing on the students' learning journals, we examine their reflections of the approaches practised on the course.…

Burke, Penny Jane; Dunn, Sue

2006-01-01

89

Dilemmas and Deliberations in Reflexive Ethnographic Research  

ERIC Educational Resources Information Center

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…

Robinson, Janean Valerie

2014-01-01

90

Neural reflexive control of a mobile robot  

Microsoft Academic Search

A control strategy for a service mobile robot in which the motion and the navigation of the vehicle are based on primitive reflexive behaviors that incorporate no a priori planning is presented. Such a scheme provides the robot with the ability to run through the whole free space of a hall with unknown obstacles while avoiding collisions, using only a

S. Faibish; G. Fruchtman; O. Dancygier

1992-01-01

91

Biological Motion Cues Trigger Reflexive Attentional Orienting  

ERIC Educational Resources Information Center

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…

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

2010-01-01

92

An architecture for reflexive autonomous vehicle control  

Microsoft Academic Search

We describe a software architecture to support the planning and control requirements of an autonomous land vehicle. This architecture is designed specifically to handle diverse terrain with maximal speed, efficacy and versatility through the use of a library of reflexive strategies specialized to particular needs. A hierarchy of control is built in which lower level modules perform tasks requiring greatest

David W. Payton

1986-01-01

93

Reflex sympathetic dystrophy: changing concepts and taxonomy  

Microsoft Academic Search

We present a revised taxonomic system for disorders previously called reflex sympathetic dystrophy (RSD) and causalgia. The system resulted from a special consensus conference that was convened on this topic and is based upon the patient's history, presenting symptoms, and findings at the time of diagnosis. The disorders are grouped under the umbrella term CRPS: complex regional pain syndrome. This

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

1995-01-01

94

Reflex Anuria After Renal Tumor Embolization  

SciTech Connect

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.

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

2007-04-15

95

The reflexive self and culture: a critique.  

PubMed

This article attempts to engage with a tendency in the theorization of social change and self-identity, evident in the work of a number of contemporary social theorists, to place an extended process of reflexivity at the heart of modern identity. As symptomatic of 'neo-modern' accounts of selfhood, critical readings of Giddens, Beck, Castells and some aspects of social theory more generally, and their account of modern reflexivity's relationship to culture, are assessed. In light of these criticisms, ways in which culture might still play an important part in the shaping of identity are considered. The relationship between language, culture and reflexivity, drawing from philosophy, sociology and G. H. Mead's own brand of social psychology, are all utilized in establishing a critique of the role Giddens and others designate for culture in the constitution of the contemporary self. By potentially repositioning self-identity in its connection to culture, the overall bearing of reflexivity upon the processes of self-identity is thus questioned. It is argued that a culturally-situated, yet fluid and multifarious account of self-identity is a necessary analytical and normative alternative. PMID:12945868

Adams, Matthew

2003-06-01

96

The reflexive self and culture: a critique  

Microsoft Academic Search

ABSTRACT This article attempts ,to engage ,with a tendency ,in the ,theorization ,of social change and self-identity, evident in the work of a number of contemporary social theorists, to place an extended process of reflexivity at the heart of modern identity. As symptomatic of ‘neo-modern’ accounts of selfhood, critical readings of Giddens, Beck, Castells and some aspects of social theory

Matthew Adams

2003-01-01

97

Der Lombard-Reflex als Stimmfunktionsprüfung  

Microsoft Academic Search

Any impairment of the audio-phonatory control by background noise is followed by an increase of the intensity level and the pitch level of the speaking voice (Lombard-Reflex, 1911) thus increasing vocal strain. Therefore, it might be expected that persons reacting to noise with very marked voice changes are more liable to develop dysphonia. In 22 singers, 35 normal persons and

H.-J. Schultz-Coulon; C.-P. Fues

1975-01-01

98

Computational Modeling of the Bremsstrahlung Reflex Triode  

NASA Astrophysics Data System (ADS)

Modeling of the operation of the reflex triode for bremsstrahlung production is being performed using 2-1/2 D particle-in-cell simulation coupled with electron-photon Monte Carlo transport models. The reflex triode employs a range-thin foil anode between two identical face-to-face hollow cathodes. Electrons undergo multiple reflexes through the anode foil converter as they lose their energy and are focused radially. Two advantages of this device over those employing a range-thick anode converter are an enhanced escape of warm x-rays (5 keV < E < 50 keV) and a mitigation of converter debris. A key focus of the simulations is reflex triode operation with composite anode foils, such as used in PITHON and DOUBLE EAGLE (Maxwell Physics International). Here, the anode has an outer range-thick annulus and an inner range-thin tantalum converter. Results will be presented for the electron deposition on the anode, the voltage, the electron and ion current, and the average number of electron passes through the anode foil, for various combinations of Ta foil thicknesses and radii, and cathode radii. The nature of strong instabilities (f ~ 0.5 GHz) in the electron flow, seen in simulations where the cathode well depth is larger than a few times the AK gap, will be analyzed. A particular emphasis in the simulations is the mitigation of noise due to grid instabilities associated with high densities (< 10^14/cm^3) near the pinch on axis.

Stark, Robert

2000-10-01

99

Ciliospinal reflex response in cluster headache.  

PubMed

The ciliospinal reflex response is mainly mediated by second- and third-order sympathetic nerves to the dilatator muscle of the iris. As the pupillary response to various pharmacological agents indicates a sympathetic dysfunction in patients with cluster headache, the ciliospinal reflex was studied in 25 patients. Five of these patients with cluster headache exhibited a Horner-like syndrome (miosis, ptosis) on the symptomatic side. The pupillary responses to phenylephrine and tyramine showed that the Horner-like syndrome was due to postganglionic sympathetic nerve dysfunction. Their ciliospinal reflex response on the symptomatic side was significantly less than in controls and in other patients with cluster headache, lacking a Horner-like syndrome. This also applied to the nonsymptomatic side compared to the majority of cluster headache patients without any clinical evidence of sympathetic nerve dysfunction. These findings seem to delineate those patients with a Horner-like syndrome as a subgroup, distinctly separated from the majority of cluster headache patients. Furthermore, the findings indicate that the Horner-like syndrome is not a consequence of repeated attacks of headache over many years, but is a manifestation of bilateral cephalic sympathetic dysfunction being more marked on the symptomatic side. In 18 (72%) of our 25 patients, an asymmetric and lower ciliospinal reflex response on the symptomatic side was seen. In 3 (12%) patients, there was no difference in the response. In 4 patients (16%), the incorrect side was indicated by an asymmetric reflex response. Two of these patients (8%) had suffered from cluster headache on alternating sides. In summary, the findings support the concept that dysfunction of the sympathetic nervous system, whether peripheral or central is involved in the pathophysiology of cluster headache. PMID:8916567

Havelius, U; Heuck, M; Milos, P; Hindfelt, B

1996-10-01

100

Quantification of jaw reflexes evoked by natural tooth contact in human subjects.  

PubMed

Inhibitory jaw reflexes are believed to be important for protecting the teeth and temporo-mandibular structures from damage during sudden or forceful biting or mastication. Accordingly, alterations in these reflexes are sometimes implicated in aetiologies proposed for oro-facial pain syndromes, although the association is not well-established. We now aim to develop a method for quantifying objectively inhibitory jaw reflexes evoked by natural tooth contact. In the longer term, this may provide a new approach to examining the association of altered reflexes and clinical conditions. Eighteen subjects gave their written, informed consent, and were recruited to participate in this study. They were instructed to clench their teeth together in response to visual cues. They performed two such tasks twenty times: from the jaw postural position and from a more open position with the jaws set 10mm apart. Both tasks produced a rapid rise then stabilisation in electromyographic activity in the masseter muscle. This was always interrupted by a large inhibitory reflex starting 11.1±1.5 ms (mean±SD) after tooth contact. The inhibitions produced during the second task were similar but of significantly longer duration (24.3±6.4 vs 18.4±6.5 ms, P=0.0003, paired t-test) and greater magnitude (measured as an integral of the waveform: 1577±478 vs 1279±425%.ms, P=0.007, paired t-test). Interestingly, in a minority (13%) of the tasks, a second inhibition with a longer latency (50.9±0.9 ms) was also observed. Thus reflex responses in the masseter muscle to natural tooth contact usually consist of single inhibitory periods. In this respect they are like those induced by externally applied tooth pushing although occasionally there is a second inhibition, reminiscent of that seen with externally applied tooth taps. PMID:21419390

Ainine, Salma; Mason, Andrew G; Cadden, Samuel W

2011-09-01

101

Impact of aging on long-term ocular reflex adaptation.  

PubMed

Compensatory eye movements (CEMs) stabilize the field of view enabling visual sharpness despite self-induced motion or environmental perturbations. The vestibulocerebellum makes it possible to adapt these reflex behaviors to perform optimally under novel circumstances that are sustained over time. Because of this and the fact that the eye is relatively insensitive to fatigue and musculoskeletal aging effects, CEMs form an ideal motor system to assess aging effects on cerebellar motor learning. In the present study, we performed an extensive behavioral examination of the impact of aging on both basic CEMs and oculomotor-based learning paradigms spanning multiple days. Our data show that healthy aging has little to no effect on basic CEM performance despite sensory deterioration, suggesting a central compensatory mechanism. Young mice are capable of adapting their oculomotor output to novel conditions rapidly and accurately, even to the point of reversing the direction of the reflex entirely. However, oculomotor learning and consolidation capabilities show a progressive decay as age increases. PMID:23880138

Gutierrez-Castellanos, Nicolas; Winkelman, Beerend H J; Tolosa-Rodriguez, Leonardo; De Gruijl, Jornt R; De Zeeuw, Chris I

2013-12-01

102

Yaw sensory rearrangement alters pitch vestibulo-ocular reflex responses  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

103

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

NASA Technical Reports Server (NTRS)

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.

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

104

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

105

Why Unergatives Select Themselves a Fake Reflexive  

E-print Network

), p. 106 participant, while congruent with current thought in semantics and the Minimalist Program. Four desiderata and three hypotheses First, Hornstein [2000], Kayne [2001], Zwart [2002] advocate the reduction of the Binding Principles to the Copy... analysis of passives, anticausatives and reflexives. In P. Cabredo Hofherr. O. Bonami, editor, Empirical Issues in Syntax and Semantics, volume 6, pages 201–225, 2006. R. Kayne. Pronouns and Their Antecedents. Blackwell Series on Generative Syntax...

Grove, Kyle Wade

2008-01-01

106

Beyond totally reflexive modules and back  

Microsoft Academic Search

\\u000a Starting from the notion of totally reflexive modules, we survey the theory of Gorenstein homological dimensions for modules\\u000a over commutative rings. The account includes the theory’s connections with relative homological algebra and with studies of\\u000a local ring homomorphisms. It ends close to the starting point: with a characterization of Gorenstein rings in terms of total\\u000a acyclicity of complexes.

Lars Winther Christensen; Hans-Bjørn Foxby; Henrik Holm

2008-01-01

107

Basic Gravitational Reflexes in the Larval Frog  

NASA Technical Reports Server (NTRS)

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.

Cochran, Stephen L.

1996-01-01

108

Cortical reflex myoclonus in Rett syndrome.  

PubMed

Rett syndrome (RS) is one of the most frequent causes of mental retardation in females. As there are no known biochemical, genetic, or morphological markers, diagnosis is based on clinical phenotype including severe dementia, autism, truncal ataxia/apraxia, loss of purposeful hand movements, breathing abnormalities, stereotypies, seizures, and extrapyramidal signs. Myoclonus, although reported in some series, has never been characterized. We studied 10 RS patients, age 3 to 20 years, and observed myoclonus in 9. Severity of myoclonus did not correlate with that of the other symptoms or with age. Multifocal, arrhythmic, and asynchronous jerks mainly involved distal limbs. Electromyographic bursts lasted 48 +/- 12 msec. Burst-locked electroencephalographic averaging generated a contralateral centroparietal premyoclonus transient preceding the burst by 34 +/- 7.2 msec. Motor evoked potentials showed normal latencies, indicating integrity of the corticospinal pathway. Somatosensory evoked potentials were enlarged. The C-reflex was hyperexcitable and markedly prolonged (62 +/- 4.3 msec), mainly due to increase in cortical relay time (28.4 +/- 4.5 msec). We conclude that RS patients show a distinctive pattern of cortical reflex myoclonus with prolonged intracortical delay of the long-loop reflex. PMID:9546328

Guerrini, R; Bonanni, P; Parmeggiani, L; Santucci, M; Parmeggiani, A; Sartucci, F

1998-04-01

109

Assessment of Hyperactive Reflexes in Patients with Spinal Cord Injury  

PubMed Central

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

Yang, Chung-Yong

2015-01-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2002-05-01

111

Context-Specific Adaptation of Gravity-Dependent Vestibular Reflex Responses  

NASA Technical Reports Server (NTRS)

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.

Shelhamer, Mark J.

1999-01-01

112

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

PubMed

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

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

1981-07-01

113

Disturbed Paraspinal Reflex Following Prolonged Flexion-Relaxation and Recovery  

PubMed Central

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

Rogers, Ellen L.; Granata, Kevin P.

2006-01-01

114

Multi-MA reflex triode research.  

SciTech Connect

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.

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

2010-08-01

115

Elbow spasticity during passive stretch-reflex: clinical evaluation using a wearable sensor system  

PubMed Central

Background Spasticity is a prevalent chronic condition among persons with upper motor neuron syndrome that significantly impacts function and can be costly to treat. Clinical assessment is most often performed with passive stretch-reflex tests and graded on a scale, such as the Modified Ashworth Scale (MAS). However, these scales are limited in sensitivity and are highly subjective. This paper shows that a simple wearable sensor system (angle sensor and 2-channel EMG) worn during a stretch-reflex assessment can be used to more objectively quantify spasticity in a clinical setting. Methods A wearable sensor system consisting of a fibre-optic goniometer and 2-channel electromyography (EMG) was used to capture data during administration of the passive stretch-reflex test for elbow flexor and extensor spasticity. A kinematic model of unrestricted passive joint motion was used to extract metrics from the kinematic and EMG data to represent the intensity of the involuntary reflex. Relationships between the biometric results and clinical measures (MAS, isometric muscle strength and passive range of motion) were explored. Results Preliminary results based on nine patients with varying degrees of flexor and extensor spasticity showed that kinematic and EMG derived metrics were strongly correlated with one another, were correlated positively (and significantly) with clinical MAS, and negatively correlated (though mostly non-significant) with isometric muscle strength. Conclusions We conclude that a wearable sensor system used in conjunction with a simple kinematic model can capture clinically relevant features of elbow spasticity during stretch-reflex testing in a clinical environment. PMID:23782931

2013-01-01

116

Effects of Static Flexion-relaxation on Paraspinal Reflex Behavior  

PubMed Central

Background. Static trunk flexion working postures and disturbed trunk muscle reflexes are related to increased risk of low-back pain. Animal studies conclude that these factors may be related; passive tissue strain in spinal ligaments causes subsequent short-term changes in reflex. Although studies have documented changes in the myoelectric onset angle of flexion-relaxation following prolonged static flexion and cyclic flexion we could find no published evidence related to the human reflex response of the trunk extensor muscles following a period of static flexion-relaxation loading. Methods. Eighteen subjects maintained static lumbar flexion for 15 min. Paraspinal muscle reflexes were elicited both before and after the flexion-relaxation protocol using pseudorandom stochastic force disturbances while recording EMG. Reflex gain was computed from the peak value of the impulse response function relating input force perturbation to EMG response using time-domain deconvolution analyses. Findings. Reflexes showed a trend toward increased gain after the period of flexion-relaxation (P < 0.055) and were increased with trunk extension exertion (P < 0.021). Significant gender differences in reflex gain were observed (P < 0.01). Interpretations. Occupational activities requiring extended periods of trunk flexion contribute to changes in reflex behavior of the paraspinal muscles. Results suggest potential mechanisms by which flexed posture work may contribute to low-back pain. Significant gender differences indicate risk analyses should consider personal factors when considering neuromuscular behavior. PMID:15567532

Granata, Kevin P.; Rogers, Ellen; Moorhouse, Kevin

2006-01-01

117

Enteropancreatic reflexes mediating the pancreatic enzyme response to nutrients.  

PubMed

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

Niebergall-Roth, Elke; Singer, Manfred V

2006-04-30

118

Iris Pigmentation and Fractionated Reaction and Reflex Time.  

ERIC Educational Resources Information Center

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…

Hale, Bruce D.; And Others

119

Reflexive Management Learning: An Integrative Review and a Conceptual Typology  

ERIC Educational Resources Information Center

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

Cotter, Richard J.; Cullen, John G.

2012-01-01

120

Stabilizing gaze reflexes in the pigeon ( Columba livia )  

Microsoft Academic Search

A quantitative study of horizontal and vertical optokinetic nystagmus (OKN) and optocollic reflex (OCR) has been performed in the pigeon using the search-coil technique. The reflexes were analysed in response to either velocity steps or sinusoidal stimulation. Results show that: 1. In response to a velocity step stimulation, the slow phase velocity of both OKN and OCR increases gradually to

H. Gioanni

1988-01-01

121

Approaches to Reflexivity: Navigating Educational and Career Pathways  

ERIC Educational Resources Information Center

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

Dyke, Martin; Johnston, Brenda; Fuller, Alison

2012-01-01

122

Reflex sympathetic imbalanceResponse to epidural blockade  

Microsoft Academic Search

Eleven patients (two male, nine female) were treated with epidural sympathetic blockade for reflex sympa thetic imbalance, an incomplete manifestation of reflex sympathetic dystrophy. Each had developed severe pain, sensitivity, and disability disproportionate to as sociated trauma. One patient injured an ankle, and the remaining 10 patients one or both knees (12 knees). Seven patients had undergone previous surgery. All

Amy L. Ladd; Kenneth E. DeHaven; Jaimala Thanik; Richard B. Patt; Michael Feuerstein

1989-01-01

123

Lombard reflex during PAG-induced vocalization in decerebrate cats  

Microsoft Academic Search

The Lombard reflex occurs when a speaker increases his vocal effort while speaking in the presence of ambient noise. The purpose of this study was to clarify whether the Lombard reflex can be evoked during controlled vocalization in an animal model. In decerebrate cats, repetitive electrical stimulation was applied to the midbrain periaqueductal gray (PAG) to evoke vocalization. Pure tone

Satoshi Nonaka; Ryuji Takahashi; Keiichi Enomoto; Akihiro Katada; T Unno

1997-01-01

124

Research paper The relationship between MOC reflex and masked threshold  

E-print Network

simultaneously with one repetition of a 300-ms masker in an ongoing train of masker bursts. Three maskingResearch paper The relationship between MOC reflex and masked threshold Angela Garinisa,*, Lynne. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold

Allen, Jont

125

Diamond graphs and super-reflexivity William B. Johnson  

E-print Network

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

Johnson, William B.

126

Abnormalities of the blink reflex in Gilles de la Tourette syndrome  

Microsoft Academic Search

The blink reflex and it's recovery cycle were studied in 26 patients with Gilles de la Tourette syndrome and 10 controls. There was a significant increase in the mean duration of the R2 response. The amplitude of the R2 response following paired shocks (mean R2[T]\\/R2[C]%) was 11%, 40% and 52% of the conditioning stimulus with intervals of 200 ms, 500

S J Smith; A J Lees

1989-01-01

127

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

PubMed Central

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

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

2014-01-01

128

Resuscitation and auto resuscitation by airway reflexes in animals  

PubMed Central

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

2013-01-01

129

Sensitivity of pulmonary chemo reflexes and lung inflation reflexes to repetitive stimulation and to inhibition with lidocaine and morphine  

Microsoft Academic Search

To study reflex responses caused by stimulation of pulmonary C-fibers and lung inflation, we used a preparation in which the left pulmonary artery and veins were ligated and cannulated and the right and left bronchi were cannulated separately in open-chest dogs. These experiments were performed to establish whether the reflex responses to injections of 150 µg of capsaicin through the

Yongyot Monsereenusorn; Sharon S. Cassidy; J. Richard Coast

1985-01-01

130

Effects of fatiguing isometric exercise upon achilles tendon reflex and plantar flexion reaction time components in man  

Microsoft Academic Search

Effects of three different fatiguing local muscular exercises upon plantar flexion reaction time and achilles tendon reflex time have been studied in 24 normal males. The Exercise Conditions, each involving a series of 30 maximal voluntary isometric contractions (MVC) of the plantar flexors, differed by allowing either 5, 10 or 20 sec rest interval between each MVC. Decrements in strength

Keith C. Hayes

1975-01-01

131

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

NASA Technical Reports Server (NTRS)

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.

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

132

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

PubMed

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

Berry, Gunnel; Svarovska, Beth

2014-08-01

133

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

134

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

PubMed

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

Tsagareli, M G; Doty, R W

2009-10-20

135

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

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

136

The oculocardiac reflex in aponeurotic blepharoptosis surgery.  

PubMed

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

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

2014-06-01

137

Conditions?  

Microsoft Academic Search

Research interests in feral hogs typically involve their negative impacts on ecosystems or their potential as a disease reservoir, especially with disease transmission to domestic swine. Authors within scientific literature state that feral hogs were captured as part of their research, but usually fail to mention specific conditions in which hogs were captured. Novice researchers of feral hogs must rely

A. Christy Wyckoff; Scott E. Henke; Kurt C. VerCauteren

138

Reversible abnormalities of the Hering Breuer reflex in acrylamide neuropathy.  

PubMed Central

The sensitivity of the Hering Breuer reflex was compared in anaesthetised rabbits before, during and after the induction of acrylamide neuropathy, and was measured as the tracheal pressure which produced 30 seconds of apnoea. After four weeks of acrylamide (400 mg/kg total dose) there was ataxia and the conduction velocity of hindlimb motor nerves was significantly reduced. At this time there was a marked and reproducible reduction in the sensitivity of the Hering Breuer reflex. The ataxia resolved within a month of stopping acrylamide administration. Three months after the cessation of acrylamide the sensitivity of the Hering Breuer reflex had increased significantly but had not returned to normal. PMID:2993526

Satchell, P

1985-01-01

139

Should the Reflex Be Reflux? Throat Symptoms and Alternative Explanations.  

PubMed

Although laryngopharyngeal reflux, also known as extraesophageal reflux (EER), was codified more than 25 years ago, it has not been characterized fully. There is no sensitive and specific diagnostic test, and its symptoms often are nonspecific and overlap with those of other conditions commonly seen in primary care and specialist practices. Otolaryngologists have an important role in the evaluation and management of these patients-they must investigate persistent reflux-attributed symptoms by direct visualization of the upper airway and larynx, and, in some circumstances, the esophagus. It is of utmost importance to rule out the possibility of malignancy, which often presents with symptoms similar to those of EER. Once cancer is excluded, many benign upper airway conditions also can masquerade as, and often incorrectly are attributed to, EER. Although reflux is a potential etiologic factor for upper-airway symptoms, it is important not to reflexively blame reflux. We discuss other etiologies that should be considered carefully for persistent symptoms. PMID:25264272

Francis, David O; Vaezi, Michael F

2014-09-26

140

Facilitation of a nociceptive flexion reflex in man by nonnoxious radiant heat produced by a laser.  

PubMed

Electromyographic recordings were made in healthy volunteers from the knee-flexor biceps femoris muscle of the nociceptive RIII reflex elicited by electrical stimulation of the cutaneous sural nerve. The stimulus intensity was adjusted to produce a moderate pricking-pain sensation. The test responses were conditioned by a nonnoxious thermal (conditioning) and electrical (test) stimuli was varied from 50 to 3, 000 ms in steps of 50 ms. It was found that the nociceptive flexion reflex was facilitated by the thermal stimulus; this modulation occurred with particular conditioning-test intervals, which peaked at 500 and 1,100 ms with an additional late, long-lasting phase between 1,600 and 2,300 ms. It was calculated that the conduction velocities of the cutaneous afferent fibers responsible for facilitating the RIII reflex, fell into three ranges: one corresponding to A delta fibers (3.2 m/s) and two in the C fiber range (1.3 and 0.7 m/s). It is concluded that information emanating from warm receptors and nociceptors converges. In this respect, the present data show, for the first time, that in man, conditioning nonnociceptive warm thermoreceptive A delta and C fibers results in an interaction at the spinal level with a nociceptive reflex. This interaction may constitute a useful means whereby signals add together to trigger flexion reflexes in defensive reactions and other basic motor behaviors. It also may contribute to hyperalgesia in inflammatory processes. The methodology used in this study appears to be a useful noninvasive tool for exploring the thermoalgesic mechanisms in both experimental and clinical situations. PMID:9582228

Plaghki, L; Bragard, D; Le Bars, D; Willer, J C; Godfraind, J M

1998-05-01

141

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

142

Speech Performance, Dysphagia and Oral Reflexes in Cerebral Palsy.  

ERIC Educational Resources Information Center

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)

Love, Russell J.; And Others

1980-01-01

143

Non-reflexive Logical Foundation for Quantum Mechanics  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

144

Reflexive Research Ethics in Fetal Tissue Xenotransplantation Research  

PubMed Central

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

Panikkar, Bindu; Smith, Natasha; Brown, Phil

2013-01-01

145

Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex.  

PubMed

The onset latency and discharge amplitude of preprogrammed postural responses were evaluated in order to determine if the structure of synergistic activation could be altered by ligamentous laxity at the knee joint. Twelve subjects with unilateral and one subject with bilateral anterior cruciate ligament (ACL) insufficiency were tested while standing on a moveable platform. External balance perturbations (6 cm anterior or posterior horizontal displacements of the platform) were presented at velocities ranging from 15 to 35 cm/s. Perturbations were presented under the following experimental conditions: unilateral and bilateral stance, knees fully straight or flexed, and with ankle motion restricted or free. These stance, knee position, and ankle motion conditions were introduced to alter the stress transmitted to the knee joint during movement of the support surface. The automatic postural response was recorded from the tibialis anterior (T), quadriceps (Q), and medial hamstrings muscles (H) bilaterally. The normal response to an externally induced backward sway involved the automatic activation of T and Q at latencies of 80 ms and 90 ms respectively. Activation of the hamstrings in the non-injured extremity was not coupled with the postural response. Hamstrings are not typically involved in the correction posterior sway because H activation would tend to pull the center of mass further backwards. However, when the response in the ACL-deficient extremity was compared to the non-injured limb: (1) the automatic postural response in the ACL-deficient extremity was restructured to include hamstrings activation (100 ms latency), (2) H activation time was faster and less variable in the ACL-deficient limb, and (3) the ratio of H/Q discharge amplitude integrated over 100 ms and 200 ms from the onset of EMG activation showed a dominance of hamstring activity during unilateral stance on the lax limb. In addition, H/Q ratios integrated over 200 ms showed dominant hamstring activity in the ACL-deficient limb during bilateral stance. (4) Cross-limb comparisons showed greater normalized IEMG amplitudes for T, H, and Q during unilateral stance on the lax limb. These results suggest that a capsular-hamstring reflex is integrated into the existing structure of a preprogrammed postural synergy in order to compensate for ligamentous laxity. Furthermore, the generalized increase of response gain observed during perturbations of unilateral stance on the lax limb indicates that joint afference can modulate central programming to control localized joint hypermobility. A concept of postural control is discussed with respect to the capsular reflex, joint loading and displacement of the center of gravity. PMID:1521607

Di Fabio, R P; Graf, B; Badke, M B; Breunig, A; Jensen, K

1992-01-01

146

Mah-Jong-induced epilepsy: a special reflex epilepsy in Chinese society.  

PubMed

We present five patients of epilepsy in which seizures were triggered by playing or watching the traditional Chinese gambling game "Mah-Jong." One patient also experienced seizures while playing a computer version of the Mah-Jong game. This condition appeared to have a predominance of males (80%) and middle-aged onset (39.4 years). Four patients had generalized tonic-clonic seizures and one patient had partial seizures with secondary generalization. No spontaneous seizure occurred in these patients. Three patients had been receiving antiepileptic drug therapy, but without effective control over their seizures. Mah-Jong-induced epilepsy is a very peculiar form of complex reflex epilepsy that involves the higher mental activities. This phenomenon may consist of distinct pathophysiologic mechanisms from other reflex epilepsy induced by thinking and spatial tasks in idiopathic generalized epilepsies. This unusual reflex epilepsy is relatively benign in nature and antiepileptic drug therapy has uncertain benefits. It may be necessary to avoid playing the Mah-Jong game in order to prevent seizures. PMID:15642495

Wan, Chin-Lung; Lin, Tsu-Kung; Lu, Cheng-Hsien; Chang, Chen-Sheng; Chen, Shang-Der; Chuang, Yao-Chung

2005-01-01

147

Reflex regulation during sustained and intermittent submaximal contractions in humans  

PubMed Central

To investigate whether the intensity and duration of a sustained contraction influences reflex regulation, we compared sustained fatiguing contractions at 25 % and 50 % of maximal voluntary contraction (MVC) force in the human abductor pollicis brevis (APB) muscle. Because the activation of motoneurones during fatigue may be reflexively controlled by the metabolic status of the muscle, we also compared reflex activities during sustained and intermittent (6 s contraction, 4 s rest) contractions at 25 % MVC for an identical duration. The short-latency Hoffmann(H) reflex and the long-latency reflex (LLR) were recorded during voluntary contractions, before, during and after the fatigue tests, with each response normalised to the compound muscle action potential (M-wave). The results showed that fatigue during sustained contractions was inversely related to the intensity, and hence the duration, of the effort. The MVC force and associated surface electromyogram (EMG) declined by 26.2 % and 35.2 %, respectively, after the sustained contraction at 50 % MVC, and by 34.2 % and 44.2 % after the sustained contraction at 25 % MVC. Although the average EMG increased progressively with time during the two sustained fatiguing contractions, the amplitudes of the H and LLR reflexes decreased significantly. Combined with previous data (Duchateau & Hainaut, 1993), the results show that the effect on the H reflex is independent of the intensity of the sustained contraction, whereas the decline in the LLR is closely related to the duration of the contraction. Because there were no changes in the intermittent test at 25 % MVC, the results indicate that the net excitatory spinal and supraspinal reflex-mediated input to the motoneurone pool is reduced. This decline in excitation to the motoneurones, however, can be temporarily compensated by an enhancement of the central drive. PMID:12068054

Duchateau, Jacques; Balestra, Costantino; Carpentier, Alain; Hainaut, Karl

2002-01-01

148

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

PubMed

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

Timmins, F

149

Neuronal application of capsaicin modulates somatic pressor reflexes.  

PubMed

Static contraction of skeletal muscle elicits a reflex increase in cardiovascular function. Likewise, noxious stimuli activate somatic nociceptors eliciting a reflex increase in cardiovascular function. On the basis of recent work involving spinothalamic cells in the dorsal horn, we hypothesized that the dorsal horn cells involved in the aforementioned reflexes would be sensitized by applying capsaicin (Cap) to a peripheral nerve. If correct, then Cap would enhance the cardiovascular increases that occur when these reflexes are evoked. Cats were anesthetized, and the popliteal fossa was exposed. Static contraction was induced by electrical stimulation of the tibial nerve at an intensity that did not directly activate small-diameter muscle afferent fibers, whereas nociceptors were stimulated by high-intensity stimulation (after muscle paralysis) of either the saphenous nerve (cutaneous nociceptors) or a muscular branch of the tibial nerve (muscle nociceptors). The reflex cardiovascular responses to these perturbations (contraction or nociceptor stimulation) were determined before and after direct application of Cap (3%) onto the common peroneal nerve, using a separate group of cats for each reflex. Compared with control, application of Cap attenuated the peak change in mean arterial pressure (MAP) evoked by static contraction (DeltaMAP in mmHg: 38 +/- 10 before and 24 +/- 8 after ipsilateral Cap; 47 +/- 10 before and 33 +/- 10 after contralateral Cap). On the other hand, Cap increased the peak change in MAP evoked by stimulation of the saphenous nerve from 57 +/- 8 to 77 +/- 9 mmHg, as well as the peak change in MAP elicited by activation of muscle nociceptors (36 +/- 9 vs. 56 +/- 14 mmHg). These results show that the reflex cardiovascular increases evoked by static muscle contraction and noxious input are differentially affected by Cap application to the common peroneal nerve. We hypothesize that a Cap-induced alteration in dorsal horn processing is the locus for this divergent effect on these reflexes. PMID:11507003

LeDoux, J F; Wilson, L B

2001-09-01

150

Auditory Brainstem Circuits That Mediate the Middle Ear Muscle Reflex  

PubMed Central

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

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

2010-01-01

151

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

PubMed

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

Wurm, Barbara

2009-03-01

152

Vergence-dependent adaptation of the vestibulo-ocular reflex  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

153

Quantitative Assessment of the Canine Pupillary Light Reflex  

PubMed Central

Purpose. To develop instrumentation and methods for thorough quantitative assessment of the pupillary light reflex (PLR) in dogs under varying stimulus conditions. Methods. The PLR was recorded in normal Dachshunds using a custom system allowing full user control over stimulus intensity, color, and duration. Chemical restraint protocols were compared to determine which protocol provided for optimal baseline stability of pupil size and appropriate eye positioning. A series of white light stimuli of increasing intensity was used to elicit pupil constriction. Pupil images were concurrently recorded using continuous infrared illumination and an infrared-sensitive camera. The PLR was also recorded in response to blue and red stimuli. Results. With injectable chemical restraint alone, spontaneous fluctuations in pupil size occurred independent of light stimulation, and spontaneous eye movements made it difficult to fully visualize the pupil. Combined injectable chemical and inhalation restraint provided a steady baseline pupil size throughout PLR assessment and allowed for stable positioning of the eye using a conjunctival stay suture. Robust PLRs were elicited with all light colors. PLR constriction amplitude increased with increasing flash intensity and ranged from 5% to 70%. Conclusions. A recording system and protocol have been developed to reliably quantify the canine PLR. The techniques and instrumentation will be useful for objective quantitative assessment of the PLR in dogs and other species in research applications and may be useful in clinical veterinary ophthalmology and neurology if PLR abnormalities detected with these procedures can be associated with specific diseases. PMID:23847311

Whiting, Rebecca E. H.; Yao, Gang; Narfström, Kristina; Pearce, Jacqueline W.; Coates, Joan R.; Dodam, John R.; Castaner, Leilani J.; Katz, Martin L.

2013-01-01

154

HPV Reflex Testing in Menopausal Women  

PubMed Central

Objective. To determine the frequency of high risk (HR) HPV and intraepithelial neoplasia following ASCUS pap cytology screens in menopausal women. Study Design. Following IRB approval, we performed a retrospective review of all cases of ASCUS pap tests, HPV results, and relevant clinical-pathologic data in women age 50 or over from November 2005 to January 2007 within a tertiary care center. Statistical analyses were performed in EXCEL. Results. 344 patients were analyzed for a total of 367 screening pap tests. 25.29% (87/344) patients were HR HPV positive, with greater percentages of HR HPV cases occurring in women age 65–74. Within HR HPV cases, 79.3% (69/87) underwent colposcopy. 27.5% (19/69) biopsy proven lesions were discovered, including cervical, vulvar or vaginal (intraepithelial neoplasia). Within the negative HR HPV group 3.1% (8/257) patients were diagnosed with dysplasia or carcinoma. Within both HR HPV positive and negative groups, patients with no prior history of lower genital tract lesions or cancer were identified. Conclusion. Reflex HPV testing plays an important role in ASCUS triage in menopausal women. Pap test screening and HPV testing should not be limited to women of reproductive age as they may aid in the diagnosis of intraepithelial neoplasia in women of older age. PMID:21559191

Ko, Emily M.; Tambouret, Rosemary; Wilbur, David; Goodman, Annekathryn

2011-01-01

155

Vestibuloocular reflex of rhesus monkeys after spaceflight  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

156

Impaired Sacculocollic Reflex in Lateral Medullary Infarction  

PubMed Central

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

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

2011-01-01

157

Driving a car using reflexive fuzzy behaviors  

SciTech Connect

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.

Pin, F.G.; Watanabe, Y.

1992-01-01

158

Driving a car using reflexive fuzzy behaviors  

SciTech Connect

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.

Pin, F.G.; Watanabe, Y.

1992-10-01

159

Gravity and Development of Cardiopulmonary Reflex  

NASA Astrophysics Data System (ADS)

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.

Nagaoka, Shunji; Eno, Yuko; Ohira, Yoshinobu

160

Processing reflexives and pronouns in picture noun phrase.  

PubMed

Binding theory (e.g., Chomsky, 1981) has played a central role in both syntactic theory and models of language processing. Its constraints are designed to predict that the referential domains of pronouns and reflexives are nonoverlapping, that is, are complementary; these constraints are also thought to play a role in online reference resolution. The predictions of binding theory and its role in sentence processing were tested in four experiments that monitored participants' eye movements as they followed spoken instructions to have a doll touch a picture belonging to another doll. The instructions used pronouns and reflexives embedded in picture noun phrases (PNPs) containing possessor phrases (e.g., Pick up Ken. Have Ken touch Harry's picture of himself). Although the interpretations assigned to pronouns were generally consistent with binding theory, reflexives were frequently assigned interpretations that violated binding theory. In addition, the timing and pattern of eye movements were inconsistent with models of language processing that assume that binding theory acts as an early filter to restrict the referential domain. The interpretations assigned to reflexives in PNPs with possessors suggest that they are binding-theory-exempt logophors, a conclusion that unifies the treatment of reflexives in PNPs. PMID:21702814

Runner, Jeffrey T; Sussman, Rachel S; Tanenhaus, Michael K

2006-03-01

161

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

PubMed Central

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

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

1988-01-01

162

A new approach to estimation of the number of central synapse(s) included in the H-reflex  

PubMed Central

Background Among the main clinical applications of the H-reflex are the evaluation of the S1 nerve root conductivity such as radiculopathy and measurement of the excitability of the spinal motoneurons in neurological conditions. An attempt has been made to reduce the pathway over which H-reflex can be obtained in a hope to localize a lesion to the S1 nerve root, so the S1 central loop has been suggested. The main goal of this study is the estimation of the H-reflex number of synapse(s) for better understanding of the physiology of this practical reflex. Methods Forty healthy adult volunteers (22 males, 18 females) with the mean age of (37.7 ± 10.2) years participated in this study. They were positioned comfortably in the prone position, with their feet off the edge of the plinth. Recording electrodes were positioned at the mid point of a line connecting the mid popliteal crease to the proximal flare of the medial malleolus. Stimulation was applied at the tibial nerve in the popliteal fossa and H, F and M waves were recorded. Without any change in the location of the recording electrodes, a monopolar needle was inserted as cathode at a point 1 cm medial to the posterior superior iliac spine, perpendicular to the frontal plane. The anode electrode was placed over the anterior superior iliac spine, and then M and H waves of the central loop were recorded. After processing the data, sacral cord conduction delay was determined by this formula: * Sacral cord conduction delay = central loop of H-reflex – (delays of the proximal motor and sensory fibers in the central loop). Results The central loop of H-reflex was (6.77 ± 0.28) msec and the sacral cord conduction delay was (1.09 ± 0.06) msec. Conclusion The sacral cord conduction time was estimated to be about 1.09 msec in this study and because at least 1 msec is required to transmit the signal across the synapse between the sensory ending and the motor cell, so this estimated time was sufficient for only one central synapse in this reflex. PMID:16011802

Ghavanini, Mohammadreza Alavian; Ashraf, Alireza; Sadeghi, Shahram; Emad, Mohammadreza

2005-01-01

163

Direct and consensual murine pupillary reflex metrics: Establishing normative values  

PubMed Central

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

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

2014-01-01

164

Reflex pathways in the abdominal prevertebral ganglia: evidence for a colo-colonic inhibitory reflex.  

PubMed Central

1. In vitro experiments were performed on preparations consisting of prevertebral ganglia attached to the entire colon of guinea-pigs. The colon was divided into an orad and a caudad segment and intraluminal pressure was recorded from the terminal end of each segment. Intracellular recordings were simultaneously obtained from neurones in the coeliac plexus. 2. The source of mechanosensory input from the colon paralleled the responses to mesenteric nerve stimulation. That is, section of the mesenteric nerve that contributed the strongest synaptic input to a neurone eliminated most of the mechanosensory input to that neurone. 3. The origin of the mechanosensory input to some neurones could be localized as coming from either the orad or caudad segment of the colon. In the coeliac ganglia 68% of the neurones tested responded primarily to orad distension and 37% to caudad distension. In the superior mesenteric ganglion 57% responded to orad distension and 43% to caudad distension. 4. Repetitive stimulation of the mesenteric nerve trunks arising from the prevertebral ganglia inhibited contractions differentially in the orad and caudad segments. The inferior coeliac nerves inhibited primarily the orad segments of colon and the lumbar colonic nerves inhibited primarily the caudad segments of colon. Stimulation of the superior coeliac nerves did not alter the motility of either segment. 5. When one of the colonic segments was distended, contractions in the other colonic segment were inhibited in 71% of the distensions. This inhibition operated in both directions: either orad inhibiting caudad or vice versa. 6. Cutting the intermesenteric nerve which communicates between the orad and caudad prevertebral ganglia eliminated the inhibitory reflex. 7. These experiments provide evidence for a colo-colonic inhibitory reflex mediated through pathways in the prevertebral ganglia. PMID:521925

Kreulen, D L; Szurszewski, J H

1979-01-01

165

Desflurane attenuates the somatosympathetic reflex in rats.  

PubMed

Arterial blood pressure and heart rate changes after afferent somatic sensory nerve stimulation are termed the "somatosympathetic reflex" (SSR). Inhibition of the SSR may partially represent an antinociceptive action. This investigation examined the actions of the volatile anesthetic, desflurane, on the SSR evoked by peripheral nerve stimulation. Rats anesthetized with alpha-chloralose (50 mg/kg) and urethane (500 mg/kg) were mechanically ventilated and cannulated with arterial and venous catheters for monitoring arterial pressure and for fluid administration, respectively. The sciatic (n = 7) or tibial (n = 6) nerves were isolated and stimulated at one, two, and four times the voltage threshold required to elicit a change in systemic hemodynamics. These cardiovascular responses were recorded before, during, and after varying concentrations of desflurane, 1.8% (0.25 minimum alveolar anesthetic concentration [MAC]), 3.6% (0.5 MAC), 7.2% (1.0 MAC), and 10.8% (1.5 MAC). Desflurane decreased arterial pressure at 1.0 and 1.5 MAC and heart rate (at more than 0.5 MAC) compared to baseline levels. Tibial nerve stimulation decreased mean arterial pressure (MAP) with no consistent changes in heart rate. Desflurane significantly attenuated this depressor response to tibial nerve stimulation (MAP decrease: control; -20 +/- 2 mm Hg versus 1.0 MAC desflurane; -6 +/- 4 mm Hg). The increases in MAP after sciatic nerve stimulation were also significantly inhibited by increasing concentrations of desflurane. At more than 0.5 MAC desflurane, the pressor response to sciatic nerve stimulation was significantly converted to a depressor response in four of seven rats (MAP: control; increase 24 +/- 2 mm Hg versus 1.0 MAC desflurane; decrease -2 +/- 4 mm Hg). Sciatic nerve stimulation also elicited increases in heart rate which were significantly attenuated by desflurane (control; 37 +/- 6 bpm versus 1.5 MAC desflurane; 0 +/- 2 bpm). These findings demonstrate that desflurane produces dose-dependent cardiovascular depression in rats and, despite previous reports of sympathoexcitation, desflurane significantly attenuated both excitatory and inhibitory types of SSR. The results of this study also support a potential antinociceptive action for this anesthetic. PMID:8659765

Ganjoo, P; Farber, N E; Schwabe, D; Kampine, J P; Schmeling, W T

1996-07-01

166

Automated data reduction workflows for astronomy. The ESO Reflex environment  

NASA Astrophysics Data System (ADS)

Context. Data from complex modern astronomical instruments often consist of a large number of different science and calibration files, and their reduction requires a variety of software tools. The execution chain of the tools represents a complex workflow that needs to be tuned and supervised, often by individual researchers that are not necessarily experts for any specific instrument. Aims: The efficiency of data reduction can be improved by using automatic workflows to organise data and execute a sequence of data reduction steps. To realize such efficiency gains, we designed a system that allows intuitive representation, execution and modification of the data reduction workflow, and has facilities for inspection and interaction with the data. Methods: The European Southern Observatory (ESO) has developed Reflex, an environment to automate data reduction workflows. Reflex is implemented as a package of customized components for the Kepler workflow engine. Kepler provides the graphical user interface to create an executable flowchart-like representation of the data reduction process. Key features of Reflex are a rule-based data organiser, infrastructure to re-use results, thorough book-keeping, data progeny tracking, interactive user interfaces, and a novel concept to exploit information created during data organisation for the workflow execution. Results: Automated workflows can greatly increase the efficiency of astronomical data reduction. In Reflex, workflows can be run non-interactively as a first step. Subsequent optimization can then be carried out while transparently re-using all unchanged intermediate products. We found that such workflows enable the reduction of complex data by non-expert users and minimizes mistakes due to book-keeping errors. Conclusions: Reflex includes novel concepts to increase the efficiency of astronomical data processing. While Reflex is a specific implementation of astronomical scientific workflows within the Kepler workflow engine, the overall design choices and methods can also be applied to other environments for running automated science workflows.

Freudling, W.; Romaniello, M.; Bramich, D. M.; Ballester, P.; Forchi, V.; García-Dabló, C. E.; Moehler, S.; Neeser, M. J.

2013-11-01

167

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

NASA Astrophysics Data System (ADS)

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.

Sebastian, C.; Horn, E.

2001-01-01

168

After stroke bidirectional modulation of soleus stretch reflex amplitude emerges during rhythmic arm cycling  

PubMed Central

Objectives: after stroke a typical presentation is exaggerated stretch reflexes (SRs) on the more affected (MA) side. The present study evaluated the contribution of presynaptic inhibition (PSI) induced by arm cycling and homosynaptic depression (HD) to the modulation of hyperreflexia at the ankle after stroke. Possible asymmetry of these effects between the MA and less affected (LA) legs was also assessed. Methods: soleus SR was conditioned by: arm cycling at 1 Hz (to increase Ia PSI); or, a preceding conditioning tendon tap applied 1 s before the test stimulus (to induce HD). The extent of conditioning effects was compared between the MA and the LA legs. Results: for both MA and LA legs, rhythmic arm movement induced a bidirectional effect in different participants, either increasing or decreasing SR amplitude (p < 0.05). HD had a significant effect in both legs (p < 0.05), however, the effect of both a previous muscle stretch and arm cycling was not different between the MA and the LA legs. Conclusion: our data reveal a bidirectional reflex modulation induced by arm cycling that produced facilitation in some and suppression in other participants after stroke. Relative SR amplitude modulation did not differ between the LA and MA legs. We speculate that alterations in SR amplitude modulation after stroke may reflect specific changes in both presynaptic afferent transmission mechanisms and fusimotor control. Significance: the present findings open new perspectives on the characterization of pathophysiology of stroke during the performance of functionally relevant motor tasks. PMID:24701201

Mezzarane, Rinaldo A.; Nakajima, Tsuyoshi; Zehr, E. P.

2014-01-01

169

Noradrenergic neurons in the rat solitary nucleus participate in the esophageal-gastric relaxation reflex.  

PubMed

Activation of esophageal mechanosensors excites neurons in and near the central nucleus of the solitary tract (NSTc). In turn, NSTc neurons coordinate the relaxation of the stomach [i.e., the receptive relaxation reflex (RRR)] by modulating the output of vagal efferent neurons of the dorsal motor nucleus of the vagus (DMN). The NSTc area contains neurons with diverse neurochemical phenotypes, including a large population of catecholaminergic and nitrergic neurons. The aim of the present study was to determine whether either one of these prominent neuronal phenotypes was involved in the RRR. Immunohistochemical techniques revealed that repetitive esophageal distension caused 53% of tyrosine hydroxylase-immunoreactive (TH-ir) neurons to colocalize c-Fos in the NSTc. No nitric oxide synthase (NOS)-ir neurons in the NSTc colocalized c-Fos in either distension or control conditions. Local brain stem application (2 ng) of alpha-adrenoreceptor antagonists (i.e., alpha1-prazosin or alpha2-yohimbine) significantly reduced the magnitude of the esophageal distension-induced gastric relaxation to approximately 55% of control conditions. The combination of yohimbine and prazosin reduced the magnitude of the reflex to approximately 27% of control. In contrast, pretreatment with either the NOS-inhibitor NG-nitro-l-arginine methyl ester or the beta-adrenoceptor antagonist propranolol did not interfere with esophageal distension-induced gastric relaxation. Unilateral microinjections of the agonist norepinephrine (0.3 ng) directed at the DMN were sufficient to mimic the transient esophageal-gastric reflex. Our data suggest that noradrenergic, but not nitrergic, neurons of the NSTc play a prominent role in the modulation of the RRR through action on alpha1- and alpha2-adrenoreceptors. The finding that esophageal afferent stimulation alone is not sufficient to activate NOS-positive neurons in the NSTc suggests that these neurons may be strongly gated by other central nervous system inputs, perhaps related to the coordination of swallowing or emesis with respiration. PMID:12714355

Rogers, R C; Travagli, R A; Hermann, G E

2003-08-01

170

VOLUME PRODUCTION OF NEGATIVE IONS IN THE REFLEX TYPE ION SOURCE  

E-print Network

coefficients in the anomalous regime of the reflex discharge.coefficient from the fluctuation spectrum in a hot cathode reflex dischargecoefficient across the magnetic field in the positive column of glow discharge

Jimbo, K.

2010-01-01

171

Rich descriptions: Evoking informant self-reflexivity in marketing and consumer research  

Microsoft Academic Search

This study seeks to extend knowledge of reflexivity theories by moving beyond a sole focus on researcher reflexivity (Bettany & Woodruffe-Burton, 2009) in considering the significance of informant self-reflexivity. It explores the promotion of informant self-reflexivity as a means to generating more in-depth interpretive data. Following the call for a ‘structured, disciplinary impetus to begin’ (Bettany & Woodruffe-Burton, 2009, p.

Amandeep Takhar; Pepukayi Chitakunye

2012-01-01

172

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

ERIC Educational Resources Information Center

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…

Dichter, Gabriel S.; Benning, Stephen D.; Holtzclaw, Tia N.; Bodfish, James W.

2010-01-01

173

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

Microsoft Academic Search

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

K. Å. Olsson; S. Landgren

1980-01-01

174

Neuroscience Letters 244 (1998) 137-140 Urethral pudendal afferent-evoked bladder and sphincter reflexes  

E-print Network

reflexes in decerebrate and acute spinal cats Susan J. Shefchyk*, R.R. Buss Department of Physiology of the urethral sensory pudendal nerve in decerebrate or acute spinal cats was used to evoke micturition reflexes sphincter activity and contribute to both guarding-like reflexes as well as suppression of sphincter

Manitoba, University of

175

Suppressive effect of pectic polysaccharides from Cucurbita pepo L. var. Styriaca on citric acid-induced cough reflex in guinea pigs  

Microsoft Academic Search

Several water-soluble pectic polysaccharides were isolated from the pumpkin fruit biomass and characterized by composition, structural features and molecular properties. The pectic polysaccharides were tested for antitussive activity by studying the effects of citric acid-induced cough reflex in guinea pigs and reactivity of the airway smooth muscle in vivo conditions in comparison to the narcotic drug codeine. Oral administration of

Gabriela Nosá?ová; ?ubica Prisenž?áková; Zuzana Koš?álová; Anna Ebringerová; Zdenka Hromádková

2011-01-01

176

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

177

Vestibuloocular reflex arc analysis using an experimentally constrained neural network  

Microsoft Academic Search

The primary function of the vestibuloocular reflex (VOR) is to maintain the stability of retinal images during head movements. This function is expressed through a complex array of dynamic and adaptive characteristics whose essential physiological basis is a disynaptic arc. We present a model of normal VOR function using a simple neural network architecture constrained by the physiological and anatomical

K. J. Quinn; Nestor A. Schmajuk; A. Jain; J. F. Baker; B. W. Peterson

1992-01-01

178

Carbon dioxide alters the Hoffmann reflex independent of hydrogen ions.  

PubMed

The purpose of this study was to examine the effect of changes in capillary blood pH on the resting soleus Hoffmann (H) reflex in the intact human. H-max size, H-wave at 20% of H-max, M-max and H-reflex latency were recorded in 10 subjects (apparently healthy, ages 19-36) before and after exposure to 3 hours of NaHCO(3), CaCO(3), NH(4)Cl (all at 0.3 g/kg) or 10 minutes 7% Carbon dioxide (CO(2)) administration. NaHCO(3) increased capillary blood pH, CaCO(3) did not change capillary blood pH, and NH(4)Cl and 7% CO(2) decreased capillary blood pH. H-max and H-wave at 20% of M-max size were significantly decreased with no change in M-max, and H-reflex latency significantly increased during 7% CO(2) administration only. No other changes in H-maximum size or H-reflex latency in response to dry chemical administration were observed. Seven percent CO(2) administration reduces the size and increases the latency of the H-maximum size as previously found, but other chemicals which alter capillary blood pH do not. CO(2) modulates afferent nerve function, and does so, it appears, independent of changes in capillary blood pH. PMID:24134189

Beekley, Matthew D

2014-07-01

179

Opening to Possibility: Reflectivity and Reflexivity in Our Teaching  

ERIC Educational Resources Information Center

This commentary explores how teachers can create a culture of tolerance by promoting reflectivity and reflexivity, and considers classroom processes and activities for doing so. "Reflectivity" is considered to be the use of personal values, experiences, and habits to make meaning and is a central tenet of inquiry approaches: to build…

Wilhelm, Jeff, Ed.

2013-01-01

180

Brief article Assignment of reference to reflexives and  

E-print Network

/him"). In two head-mounted eye-tracking experiments, listeners frequently violated Binding Theory predictions to be the antecedent of `him'. We tested this prediction using the head-mounted eye-tracking paradigm (Tanenhaus containing reflexives and pronouns. 2. Experiment 1 Participants were seated in front of the display pictured

DeAngelis, Gregory

181

The reflex-diode HPM source on Aurora  

Microsoft Academic Search

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

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

1990-01-01

182

The reflex-diode HPM source on Aurora  

Microsoft Academic Search

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

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

1990-01-01

183

Control of volitional and reflexive saccades in Tourette's syndrome  

E-print Network

Control of volitional and reflexive saccades in Tourette's syndrome Adrienne L. LeVasseur1, J and 3 Medicine, Queen's University, Kingston, Ontario, Canada Tourette's syndrome is characterized by involuntary tics and, although the underlying pathogenesis and pathophysiology of Tourette's syndrome remains

Munoz, Douglas Perry

184

A Reflective--Reflexive View of Women and Leadership  

ERIC Educational Resources Information Center

This article reflects the author's personal experiences through a reflective-reflexive view of women and leadership. Significant writings on women and leadership, particularly Rhode(2003) "The Difference "Difference" Makes: Women and Leadership", are included in the analysis. (Contains 4 notes.)

Moss, Glenda

2004-01-01

185

Enhancing the Reflexivity of System Innovation Projects with System Analyses  

ERIC Educational Resources Information Center

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…

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

2010-01-01

186

Ontogeny of Infantile Oral Reflexes and Emerging Chewing.  

ERIC Educational Resources Information Center

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)

Sheppard, Justine Joan; Mysak, Edward D.

1984-01-01

187

The pathway controlling the pupillary light reflex in urodeles  

Microsoft Academic Search

Although the photomechanical response of the iris in amphibians has been characterized, the central pathway of reflex control is unknown. We investigated this pathway by electrophysiological and anatomical techniques in urodeles. Sustained responding neurons in the pretectum were localized and characterized. Three neuron types were found and compared with tonic neurons in mammals. They were driven by the contralateral retina

Jacqueline Henning; Werner Himstedt

1994-01-01

188

Positioning Resumes and Cover Letters as Reflective-Reflexive Process  

ERIC Educational Resources Information Center

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…

Randazzo, Chalice

2012-01-01

189

Dilemma of a Native: On Location, Authenticity, and Reflexivity  

Microsoft Academic Search

With the focus on native\\/halfie anthropology, I address in this paper three issues of location, authenticity, and reflexivity of the anthropologist in close connection to the reality of uneven distribution of power inside academe among scholars and institutions, and, above all, anthropologists, including native anthropologists. I emphasise that interaction between the field and the ethnographer never closes even after the

Sonia Ryang

2005-01-01

190

Aerial Righting Reflexes in Flightless Animals Ardian Jusufi,1,  

E-print Network

relevance to subsequent aerial performance in parachuting and gliding animals. Geckos can use rotation or parachuting posture, and ultimately land safely. The aerial righting reflex has traditionally been seen for recovery from an inverted body orienta- tion while in midair is thought to be well-developed in classical

191

Approaching Reflexivity through Reflection: Issues for Critical Management Education  

ERIC Educational Resources Information Center

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

Hibbert, Paul

2013-01-01

192

Practicing Reflexivity in the Study of Italian Migrants in London  

ERIC Educational Resources Information Center

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…

Seganti, Francesca Romana

2010-01-01

193

Foveation dynamics in congenital nystagmus III: Vestibulo-ocular reflex  

Microsoft Academic Search

It has been shown that, during fixation of a stationary target with a fixed head, an individual with congenital nystagmus (CN) can repeatedly (beat-to-beat) foveate (within 13 minarc) and maintain low retinal slip velocities (less than 4°\\/sec). With the head in motion, vestibuloocular reflex (VOR) data showed eye velocities during these foveation periods that approximation head veloicty. Despite some claims

L. F. Dell'Osso; J. Steen; R. M. Steinman; H. Collewijn

1992-01-01

194

Ia reflexes and EPSPs in human soleus motor neurones  

Microsoft Academic Search

The reflex responses of single motor units in the soleus muscle to electrical stimulation of the tibial nerve were recorded in human volunteers. A feature of the experiments was the stimulation paradigm used. In order to control the peristimulus firing rate, a computer triggered the stimulus isolator only when 2 interspike intervals of specified duration occurred in succession. In addition,

T. S. Miles; K. S. Türker; T. H. Le

1989-01-01

195

Particle-In-Cell Modeling of the Bremsstrahlung Reflex Triode  

NASA Astrophysics Data System (ADS)

Modeling of the operation of the reflex triode for bremsstrahlung production is being performed using 2-1/2 D particle-in-cell simulation. The reflex triode employs a range-thin foil anode between two identical face-to-face hollow cathodes. Electrons undergo multiple reflexes through the anode foil converter as they lose their energy and are focused radially. Two advantages of this device over those employing a range-thick anode converter are an enhanced escape of warm x-rays (5 keV < E < 50 keV) and a mitigation of converter debris. Computational results for the sensitivity of reflex triode operation to anode foil thickness (tantalum) will be presented. No sensitivity of ion or total current with foil thickness is observed. Strong plasma oscillations are seen at the foil near the axis of symmetry, which degrade the radial confinement of the electrons. For this reason an energetic tail is observed in the electron spectrum, and the sensitivity of the average number of passes of electrons through the foil is weaker than 1/thickness. For cathode well depths larger than a few times the AK gap, a strong instability (f 0.5 GHz) is seen in the electron flow in the cathode wells.

Stark, Robert

1999-11-01

196

Differential cortical activation during voluntary and reflexive saccades in man  

Microsoft Academic Search

A saccade involves both a step in eye position and an obligatory shift in spatial attention. The traditional division of saccades into two types, the “reflexive” saccade made in response to an exogenous stimulus change in the visual periphery and the “voluntary” saccade based on an endogenous judgement to move gaze, is supported by lines of evidence which include the

Dominic J Mort; Richard J Perry; Sabira K Mannan; Timothy L Hodgson; Elaine Anderson; Rebecca Quest; Donald McRobbie; Alan McBride; Masud Husain; Christopher Kennard

2003-01-01

197

Supranodose vagotomy precludes reflex respiratory responses to serotonin in cats  

Microsoft Academic Search

Mediation of the respiratory reflex effects of an exogenous serotonin challenge goes beyond the lung vagi and is suggested to involve the nodose ganglia. In the present experiments the effects of an intravenous serotonin challenge on breathing pattern were studied in 8 pentobarbitone-chloralose anaesthetised cats. Bolus injection of serotonin oxalate (50 µg\\/kg) into the right femoral vein evoked prompt apnoea

Beata Kopczy?ska; Ma?gorzata Szereda-Przestaszewska

2003-01-01

198

Control of Bipedal Walking Exploiting Postural Reflexes and Passive Dynamics  

E-print Network

to disturbances as elaborate feedback mechanisms are rarely present. Furthermore, mostly simplified kinematics like planar walkers have been examined, the few 3D models achieve only T. Luksch and K. Berns with rising complexity. Similarly, CPG and reflex based approaches have mostly been applied to only planar

Berns, Karsten

199

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

PubMed

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

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

2014-03-01

200

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

201

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

PubMed Central

The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses. A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level. We recorded EMG from eight subjects walking (1.25 m s?1) and running (3.0 m s?1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by ?30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9%Mmax) than running (-2.5%Mmax; P < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion. PMID:11136869

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

2001-01-01

202

An analogue of growth hormone releasing factor (GRF), (Ac-Try1, D-Phe2)-GRF-(1-29), specifically antagonizes the facilitation of the flexor reflex induced by intrathecal vasoactive intestinal peptide in rat spinal cord.  

PubMed

The effect of intrathecal (i.t.) vasoactive intestinal peptide (VIP) and an analogue of growth hormone releasing factor (GRF) with putative VIP antagonistic property, (Ac-Try1, D-Phe2)-GRF-(1-29), on the nociceptive flexor reflex was studied in decerebrate, spinalized, unanesthetized rats. VIP (10 pM) facilitated the flexor reflex for several minutes. A similar facilitation was induced by the VIP antagonist applied i.t. with a potency 15 times less than that of VIP. Pre-administration of the VIP antagonist dose-dependently antagonized the reflex facilitation by i.t. VIP. In contrast, the reflex facilitation induced by i.t. substance P, somatostatin, calcitonin gene-related peptide and galanin was not influenced by the VIP-antagonist. The VIP antagonist by itself did not depress the flexor reflex over the dose range of 3 pM-3 nM and neither did it block the facilitation of the flexor reflex induced by a brief conditioning electrical stimulus train that activated the C-afferents in skin innervated by the sural nerve. The present results indicate that this GRF analogue is an effective and specific VIP antagonist in the rat spinal cord. Furthermore, it is suggested that VIP may not be involved in the transmission of cutaneous nociceptive information under normal conditions. PMID:2067598

Xu, X J; Wiesenfeld-Hallin, Z

1991-03-01

203

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

PubMed Central

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

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

1996-01-01

204

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

PubMed

Reflex blinks provide a model system for investigating motor learning in normal and pathological states. We investigated whether high-frequency stimulation (HFS) of the supraorbital branch of the trigeminal nerve before the R2 blink component (HFS-B) decreases reflex blink gain in alert rats. As with humans (Mao JB, Evinger C. J Neurosci 21: RC151, 2001), HFS-B significantly reduced blink size in the first hour after treatment for rats. Repeated days of HFS-B treatment produced long-term depression of blink circuits. Blink gain decreased exponentially across days, indicating a long-term depression of blink circuits. Additionally, the HFS-B protocol became more effective at depressing blink amplitude across days of treatment. This depression was not habituation, because neither long- nor short-term blink changes occurred when HFS was presented after the R2. To investigate whether gain modifications produced by HFS-B involved cerebellar networks, we trained rats in a delay eyelid conditioning paradigm using HFS-B as the unconditioned stimulus and a tone as the conditioned stimulus. As HFS-B depresses blink circuits and delay conditioning enhances blink circuit activity, occlusion should occur if they share neural networks. Rats acquiring robust eyelid conditioning did not exhibit decreases in blink gain, whereas rats developing low levels of eyelid conditioning exhibited weak, short-term reductions in blink gain. These results suggested that delay eyelid conditioning and long-term HFS-B utilize some of the same cerebellar circuits. The ability of repeated HFS-B treatment to depress trigeminal blink circuit activity long term implied that it may be a useful protocol to reduce hyperexcitable blink circuits that underlie diseases like benign essential blepharospasm. PMID:24285868

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

2014-02-01

205

Reflex regulation of airway sympathetic nerves in guinea-pigs  

PubMed Central

Sympathetic nerves innervate the airways of most species but their reflex regulation has been essentially unstudied. Here we demonstrate sympathetic nerve-mediated reflex relaxation of airway smooth muscle measured in situ in the guinea-pig trachea. Retrograde tracing, immunohistochemistry and electrophysiological analysis identified a population of substance P-containing capsaicin-sensitive spinal afferent neurones in the upper thoracic (T1–T4) dorsal root ganglia (DRG) that innervate the airways and lung. After bilateral vagotomy, atropine pretreatment and precontraction of the trachealis with histamine, nebulized capsaicin (10–60 ?m) evoked a 63 ± 7% reversal of the histamine-induced contraction of the trachealis. Either the ?-adrenoceptor antagonist propranolol (2 ?m, administered directly to the trachea) or bilateral sympathetic nerve denervation of the trachea essentially abolished these reflexes (10 ± 9% and 6 ± 4% relaxations, respectively), suggesting that they were mediated primarily, if not exclusively, by sympathetic adrenergic nerve activation. Cutting the upper thoracic dorsal roots carrying the central processes of airway spinal afferents also markedly blocked the relaxations (9 ± 5% relaxation). Comparable inhibitory effects were observed following intravenous pretreatment with neurokinin receptor antagonists (3 ± 7% relaxations). These reflexes were not accompanied by consistent changes in heart rate or blood pressure. By contrast, stimulating the rostral cut ends of the cervical vagus nerves also evoked a sympathetic adrenergic nerve-mediated relaxation that were accompanied by marked alterations in blood pressure. The results indicate that the capsaicin-induced reflex-mediated relaxation of airway smooth muscle following vagotomy is mediated by sequential activation of tachykinin-containing spinal afferent and sympathetic efferent nerves innervating airways. This sympathetic nerve-mediated response may serve to oppose airway contraction induced by parasympathetic nerve activation in the airways. PMID:16581869

Oh, Eun Joo; Mazzone, Stuart B; Canning, Brendan J; Weinreich, Daniel

2006-01-01

206

A reflexive neural network for dynamic biped walking control.  

PubMed

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

Geng, Tao; Porr, Bernd; Wörgötter, Florentin

2006-05-01

207

Nitrous oxide depresses somatocardiac sympathetic A- and C-reflexes in anesthetized rats.  

PubMed

Effect of nitrous oxide (N2O) on the somatosympathetic A- and C-reflexes was investigated using artificially ventilated rats anesthetized with alpha-chloralose and urethane. Somatocardiac sympathetic A- and C-reflexes were elicited in the inferior cardiac nerve by electrical stimulation of A and C afferent fibers of the tibial nerve, respectively. Both reflexes were depressed by inhalation of N2O for 20 min. The depression was greater in the C-reflex than in the A-reflex. The depressive effects of N2O on both reflexes were unchanged after pretreatment with intravenous naloxone (0.2 or 2.0 mg/kg) or by prolongation of the inhalation of N2O for 2 h. These results suggest that the opioid receptor is not involved and that acute tolerance is not developed in the depressive action of N2O on the somatosympathetic A- and C-reflexes. PMID:8844712

Adachi, T; Miyazaki, Y; Kurata, J; Utsumi, J; Shinomura, T; Nakao, S; Murakawa, M; Shichino, T; Mori, K

1996-07-26

208

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

PubMed Central

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

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

2014-01-01

209

Angiotensin AT1 receptor blockade abolishes the reflex sympatho-excitatory response to adenosine.  

PubMed Central

We tested the hypothesis that endogenous angiotensin II participates in the direct and reflex effects of adenosine on the sympathetic nervous system. Nine healthy men were studied after 1 wk of the angiotensin II type I receptor antagonist losartan (100 mg daily) or placebo, according to a double-blind randomized crossover design. Bilateral forearm blood flows, NE appearance rates, and total body NE spillover were determined before and during graded brachial arterial infusion of adenosine (0.5, 1.5, 5, and 15 microg/100 ml forearm tissue) and nitroprusside. Adenosine increased total body NE spillover (P < 0.05) whereas nitroprusside did not. Losartan lowered BP (P < 0.05), had no effect on total body NE spillover at rest, or forearm vasodilation during either infusion, but reduced the systemic noradrenergic response to adenosine from 1.0+/-0.4 nmol/min on the placebo day to 0.2+/-0.3 nmol/min (P < 0.01), and forearm NE appearance rate in response to adenosine was lower in the infused, as compared with the contralateral arm (P = 0.04). The sympatho-excitatory reflex elicited by adenosine is mediated through pathways involving the angiotensin II type I receptor. Interactions between adenosine and angiotensin II may assume importance during ischemia or congestive heart failure and could contribute to the benefit of converting enzyme inhibition in these conditions. PMID:9466971

Rongen, G A; Brooks, S C; Ando, S i; Abramson, B L; Floras, J S

1998-01-01

210

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

PubMed

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

Dicpinigaitis, Peter V

2014-10-01

211

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

212

Early Modern ET, Reflexive Telescopics, and Their Relevance Today  

NASA Astrophysics Data System (ADS)

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.

Danielson, Dennis

213

Femoral Artery Occlusion Increases Muscle Pressor Reflex and Expression of Hypoxia-Inducible Factor-1? in Sensory Neurons  

PubMed Central

Hypoxia inducible factor-1 (HIF-1) has an important contribution to pathophysiological changes of homeostasis under conditions of oxygen deprivation as well as ischemia. We examined the effects of femoral artery occlusion on HIF-1? expression in sensory dorsal root ganglion (DRG) neurons of rats. Also, we examined cardiovascular responses to static muscle contraction following femoral occlusion. We hypothesized that hindlimb vascular insufficiency increases the levels of sensory nerves’ HIF-1? and augments autonomic responses induced by activation of muscle afferent nerves. In addition, we examined if the reflex cardiovascular responses were altered as HIF-1? was increased in the DRG neurons. Our data show that HIF-1? was significantly increased in the lumbar DRG neurons 6, 24 and 72 hours after femoral artery ligation as compared with sham control. Administration of dimethyloxalylglycine (DMOG), a stabilizer of HIF-?, significantly increased HIF-1? in the lumbar DRG neurons. Furthermore, femoral occlusion enhanced the reflex pressor response to muscle contraction; however, the response was not altered by injection of DMOG. Overall, our results indicate that 1) femoral artery occlusion increases HIF-1? levels of in DRG neurons and contraction-induced pressor response; and 2) an increase in HIF-1? of DRG neurons per se may not alter the muscle pressor reflex. PMID:25346936

Gao, Wei; Li, Jianhua

2013-01-01

214

[The effects of the orbital cortex on the neuronal activity of the tegmentum mesencephali in a food reflex in cats].  

PubMed

In chronic experiments on cat influences of functional exclusion of the orbital cortex on the rearrangement neuronal activity of the midbrain tegmentum on performance of food-acquiring conditioned reflexes have studied. Most neurons showed decreased firing rate responses increased latency and increase of number short interspike intervals accompanied by changes in parameters of the food-acquiring responses: increase latent periods and long persistence of electromyogram. The above-noted facts have shown that the most obvious excitatory influences to the midbrain tegmentum from orbital cortex in the period of initiation condition motor response. PMID:7581579

Driagin, Iu M

1995-04-01

215

Frequency tuning of the contralateral medial olivocochlear reflex in humans  

PubMed Central

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

Dhar, Sumitrajit

2012-01-01

216

Cough reflex sensitivity in various phenotypes of childhood asthma.  

PubMed

Cough is a major symptom in some children with asthma, but the relationship between cough and the severity of asthma is defined insufficiently. As cough represents common problem of pediatrics, several objective methods for its assessment were developed. Cough reflex sensitivity (CRS) test with capsaicin is one of the most important tools for studying cough. In the present study, we aimed to study the CRS in various phenotypes of childhood asthma. We found that, in general, CRS was increased in asthmatic children compared with controls. The most evident increase of CRS was observed during acute asthma exacerbation, in children suffering from asthma with concomitant allergic rhinitis, and in atopic asthmatics. Interestingly, we noted a significant decline in lung function after capsaicin CRS. Various laboratory and clinical characteristics of asthmatic children influence cough sensitivity to a different extent. Cough reflex sensitivity measurement can add valuable information beside the commonly used spirometric and inflammometric methods in the management of asthmatic children. PMID:20134041

Jesenak, M; Babusikova, E; Petrikova, M; Turcan, T; Rennerova, Z; Michnova, Z; Havlicekova, Z; Villa, M P; Banovcin, P

2009-11-01

217

An unusual case of benign reflex myoclonic epilepsy of infancy.  

PubMed

A previously healthy one-year-old boy, the youngest child of unrelated parents, presented with a four-week history of episodes of myoclonus triggered only by tactile stimulation to his head. There had been no loss of developmental skills. The electroencephalogram (EEG) revealed generalised polyspike wave activity both with and without clinical correlate. The infant was started on sodium valproate, which resulted in cessation of the myoclonic episodes one week after starting therapy. At subsequent follow-up (at 18 months) the infant was seizure free and a repeat EEG was normal. This case of non-progressive reflex myoclonic epilepsy of infancy triggered only by head tapping (and not by acoustic stimuli) is an extremely rare phenomenon. Reflex myoclonic epilepsy of infancy represents a distinct subtype of myoclonic epilepsy in infancy. It should be considered as an age-dependent idiopathic generalised epileptic syndrome with an apparently good prognosis. PMID:12910440

Kurian, M A; King, M D

2003-06-01

218

Peripheral ?-opioid receptors attenuate the exercise pressor reflex  

PubMed Central

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

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

2013-01-01

219

The development of reflexes and behavior in the rabbit  

E-print Network

and defe- cation, accomplished by stroking the external genitalia (Fox 1965). Williams and Scott (1953) likewise observed this in the mouse. The onset of extensor dominance marks the beginning of the second period of neurological development... explain the lack of spinal extension. Since the rabbit also failed to show strong flexor dominance, it is possible that this pattern of development is absent in this species. Another reflex described in the dog (Fox 1965) and mouse (Williams & Scott...

Finn, Miguelita Whelan

2012-06-07

220

Increased Auditory Startle Reflex in Children with Functional Abdominal Pain  

Microsoft Academic Search

Objective To test the hypothesis that children with abdominal pain-related functional gastrointestinal disorders have a general hypersensitivity for sensory stimuli. Study design Auditory startle reflexes were assessed in 20 children classified according to Rome III classifications of abdominal pain-related functional gastrointestinal disorders (13 irritable bowel syndrome [IBS], 7 functional abdominal pain syndrome; mean age, 12.4 years; 15 girls) and 23

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

2010-01-01

221

Influence of gravity on cat vertical vestibulo-ocular reflex  

Microsoft Academic Search

The vertical vestibulo-ocular reflex (VOR) was recorded in cats using electro-oculography during sinusoidal angular pitch. Peak stimulus velocity was 50°\\/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,

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

1988-01-01

222

Trait Dominance Promotes Reflexive Staring at Masked Angry Body Postures  

PubMed Central

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

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

2014-01-01

223

Motion perception correlates with volitional but not reflexive eye movements.  

PubMed

Visually-driven actions and perception are traditionally ascribed to the dorsal and ventral visual streams of the cortical processing hierarchy. However, motion perception and the control of tracking eye movements both depend on sensory motion analysis by neurons in the dorsal stream, suggesting that the same sensory circuits may underlie both action and perception. Previous studies have suggested that multiple sensory modules may be responsible for the perception of low- and high-level motion, or the detection versus identification of motion direction. However, it remains unclear whether the sensory processing systems that contribute to direction perception and the control of eye movements have the same neuronal constraints. To address this, we examined inter-individual variability across 36 observers, using two tasks that simultaneously assessed the precision of eye movements and direction perception: in the smooth pursuit task, observers volitionally tracked a small moving target and reported its direction; in the ocular following task, observers reflexively tracked a large moving stimulus and reported its direction. We determined perceptual-oculomotor correlations across observers, defined as the correlation between each observer's mean perceptual precision and mean oculomotor precision. Across observers, we found that: (i) mean perceptual precision was correlated between the two tasks; (ii) mean oculomotor precision was correlated between the tasks, and (iii) oculomotor and perceptual precision were correlated for volitional smooth pursuit, but not reflexive ocular following. Collectively, these results demonstrate that sensory circuits with common neuronal constraints subserve motion perception and volitional, but not reflexive eye movements. PMID:25073044

Price, N S C; Blum, J

2014-09-26

224

Neurons of rostral ventrolateral medulla mediate somatic pressor reflex.  

PubMed

The somatic pressor reflex (SPR) elicited in anesthetized paralyzed rats by electrical stimulation of the sciatic or sural cutaneous afferent nerves produced an increase in arterial pressure ranging from 5 to 40 mmHg. Stimulation of femoral or tibial afferent nerves from muscle produced a depressor response. The SPR was not affected by midpontine transection but was eliminated either by hemisection of the lumbar spinal cord contralateral, but not ipsilateral, to the stimulated nerve or by electrolytic or kainic acid lesion of the contralateral, but not ipsilateral, rostral ventrolateral medulla (RVL). Stimulation of the brachial plexus elicited an SPR that was not eliminated by contralateral lumbar hemisection but was abolished by RVL lesion. RVL lesions consistently overlapped areas containing phenylethanolamine N-methyltransferase-labeled C1 adrenergic neurons. Kainic acid injections into the lateral reticular nucleus (LRN) did not affect the SPR. Neither contralateral nor ipsilateral electrolytic lesions of other autonomic areas including parabrachial nucleus, the nucleus tractus solitarii, the A5 region, or the inferior cerebellar peduncle (output pathway of the LRN) affected the reflex. In axonal transport studies using horseradish peroxidase, afferent terminals of the sciatic nerve were shown to overlap spinoreticular neurons in the dorsal horn retrogradely labeled from tracer injections in the RVL. We conclude that the SPR can be elicited in rats, that it is mediated by spinoreticular afferents traveling in the contralateral spinal cord, and that the C1 adrenergic area of the RVL is a critical region for the integration of the somatic pressor reflex. PMID:2464948

Stornetta, R L; Morrison, S F; Ruggiero, D A; Reis, D J

1989-02-01

225

Particle-in-cell modeling of the bremsstrahlung reflex triode  

NASA Astrophysics Data System (ADS)

Modeling of the operation of the reflex triode for bremsstrahlung production is being performed using the 2-1/2 D particle-in-cell (PIC) code MAGIC (Mission Research Corp). The reflex triode employs a range-thin foil anode between two identical face-to-face hollow cathodes. Electrons undergo multiple reflexes through the anode foil as they lose their energy and are focused radially. The range-thin anode enhances the escape of warm x-rays (5 keV < E < 50 keV). Peak voltages range from a few hundred kilovolts to over a megavolt, depending on the desired x-ray radiation spectrum. Results of PIC simulations will be presented for the typical electron trajectories and the radial profile of the electron energy loss in the foil anode and radiation spectrum. Also presented will be simulations of the effect of the anode plasma on the electron orbits. Finally, analytic modeling of the formation and expansion of the anode plasma will be presented.

Stark, Robert

1998-11-01

226

The effect of increasing the innervation field sizes of nerves on their reflex response time in salamanders  

PubMed Central

1. A simple quantitative measure was sought which could describe the relationship between reflex coupling in the spinal cord of salamanders and the peripheral innervation fields of the nerves from which the reflexes were elicited. 2. In decerebrate salamanders reflex responses were recorded between pairs of cut hind limb nerves. The latencies (S/R times) of these reflex responses were bilaterally symmetrical for a given pair of nerves and were shorter when the stimulated nerve of the pair had a large motor and sensory peripheral limb innervation field; this was especially obvious for reflexes between 15th and 17th segmental nerves. 3. After cutting or crushing the 16th nerve in adult salamanders, the adjacent 15th and 17th nerves sprouted collaterally to innervate denervated skin and muscle. There was apparently complete recovery of normal tactile reflexes and walking movements within a month. 4. The operation did not affect the reflex response (S/R) times for nerve combinations on the unoperated side, which were not significantly different from those of normal animals with similar sized peripheral nerve fields. The unoperated side therefore represented the preoperative condition. 5. In animals where one or both the 15th and 17th nerves had increased its innervation field size, the S/R times between them were significantly shorter on the operated side when the nerve with the enlarged field was stimulated. The degree of shortening was greatest for nerves showing the largest increase in peripheral field area. 6. The S/R times between the 15th and 17th nerves were similar to those measured in normal animals in which the peripheral fields were of similar size to the enlarged fields in the operated animals. In a few cases where the increase in field size was considerable, the S/R time between the 15th and 17th nerves became as short as that between the 15th and 16th nerves on the control side. 7. After removal of the 15th nerve, the 14th nerve sprouted into the trunk skin and muscle previously innervated by the 15th nerve and the 16th nerve into denervated limb skin and muscle. In spite of the increased peripheral fields of both these nerves, there was no change in the S/R times between them, or between any other pair of limb nerves on the operated side. 8. The decrease in the S/R times between the 15th and 17th nerves was only observed where the stimulated nerve had increased its peripheral limb innervation field. The possible causes and significance of this shortening reflex response times are discussed in the context of an apparently functionally appropriate adaptation in the spinal cord. PMID:4693677

Stirling, R. Victoria

1973-01-01

227

An Iterative Algorithm for the Reflexive Solution of the General Coupled Matrix Equations  

PubMed Central

The general coupled matrix equations (including the generalized coupled Sylvester matrix equations as special cases) have numerous applications in control and system theory. In this paper, an iterative algorithm is constructed to solve the general coupled matrix equations over reflexive matrix solution. When the general coupled matrix equations are consistent over reflexive matrices, the reflexive solution can be determined automatically by the iterative algorithm within finite iterative steps in the absence of round-off errors. The least Frobenius norm reflexive solution of the general coupled matrix equations can be derived when an appropriate initial matrix is chosen. Furthermore, the unique optimal approximation reflexive solution to a given matrix group in Frobenius norm can be derived by finding the least-norm reflexive solution of the corresponding general coupled matrix equations. A numerical example is given to illustrate the effectiveness of the proposed iterative algorithm. PMID:24324386

Zhou, Zhongli; Huang, Guangxin

2013-01-01

228

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

PubMed

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

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

2015-03-01

229

GABAergic inhibition of hiccup-like reflex induced by electrical stimulation in medulla of cats  

Microsoft Academic Search

We hypothesize that the hiccup reflex is actively inhibited through GABAB receptor within central connections of the hiccup reflex arc. Because the hiccup-like reflex can be elicited by electrical stimulation to a limited area within the medullary reticular formation, the hiccup-evoking site (HES), electrical stimulation (50–100 ?A, three train pulses at 20 Hz) was delivered to HES by means of

Tsutomu Oshima; Masahiro Sakamoto; Hideki Tatsuta; Hideho Arita

1998-01-01

230

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

PubMed Central

Background Females have a higher risk of experiencing low back pain or injury than males. One possible reason for this might be altered reflexes since longer paraspinal reflex latencies exist in injured patients versus healthy controls. Gender differences have been reported in paraspinal reflex latency, yet findings are inconsistent. The goal here was to investigate gender differences in paraspinal reflex latency, avoiding and accounting for potentially gender-confounding experimental factors. Methods Ten males and ten females underwent repeated trunk flexion perturbations. Paraspinal muscle activity and trunk kinematics were recorded to calculate reflex latency and maximum trunk flexion velocity. Two-way mixed model ANOVAs were used to determine the effects of gender on reflex latency and maximum trunk flexion velocity. Findings Reflex latency was 18.7% shorter in females than in males (P=0.02) when exposed to identical trunk perturbations, and did not vary by impulse (P=0.38). However, maximum trunk flexion velocity was 35.3% faster in females than males (P=0.01) when exposed to identical trunk perturbations, and increased with impulse (P<0.01). While controlling for differences in maximum trunk flexion velocity, reflex latency was 16.4% shorter in females than males (P=0.04). Implications The higher prevalence of low back pain and injury among females does not appear to result from slower paraspinal reflexes. PMID:20359800

Miller, Emily M.; Slota, Gregory P.; Agnew, Michael J.; Madigan, Michael L.

2010-01-01

231

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

PubMed

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

LeMoyne, Robert; Mastroianni, Timothy

2014-08-01

232

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

PubMed Central

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

Shemmell, Jonathan

2015-01-01

233

[The somato-sympathetic and somato-somatic reflexes in the spontaneous hypertensive rats].  

PubMed

In anaesthetized normotensive (Wistar) and hypertensive (SHR) rats, sympathetic and somatic reflexes were studied before and after cervical spinal cord transection. Single shock stimulation of a peripheral afferent nerve of brachial plexus produced reflex discharges in the cervical sympathetic trunk and the radial nerve. In rats with intact brain stem, evoked response in the cervical sympathetic trunk was composed of three components, but evoked response in radial nerve consisted of two components. The total somato-sympathetic reflex in hypertensive rats was more on 54 % than the somato-sympathetic reflex in normotensive rats. The total somato-somatic reflex in hypertensive rats was more on 70 % than the somato-somatic reflex in normotensive rats. In rats with transected brain stem, evoked response in the cervical sympathetic trunk was composed of two components, but evoked response in radial nerve consisted of one component. After neuraxis transection the total sympathetic and somatic reflexes in normotensive rats decreased by 85 and 83 %, respectively. The total sympathetic and somatic reflexes in hypertensive rats decreased by 88 and 84 %, respectively. However, the peak value of evoked discharges in sympathetic and somatic nerves were more in hypertensive rats than in normotensive rats. Suprasegmental and spinal mechanisms responsible for the augmentation of both sympathetic and somatic reflexes are discussed. PMID:25464722

Shcherbin, Iu I; Tsyrlin, V A

2014-01-01

234

H-reflex modulation in the human medial and lateral gastrocnemii during standing and walking  

PubMed Central

Introduction The soleus H-reflex is dynamically modulated during walking. However, modulation of the gastrocnemii H-reflexes has not been studied systematically. Methods The medial and lateral gastrocnemii (MG and LG) and soleus H-reflexes were measured during standing and walking in humans. Results Maximum H-reflex amplitude was significantly smaller in MG (mean 1.1 mV) or LG (1.1 mV) than in soleus (3.3 mV). Despite these size differences, the reflex amplitudes of the three muscles were positively correlated. The MG and LG H-reflexes were phase- and task-dependently modulated in ways similar to the soleus H-reflex. Discussion Although there are anatomical and physiological differences between the soleus and gastrocnemii muscles, the reflexes of the three muscles are similarly modulated during walking and between standing and walking. The findings support the hypothesis that these reflexes are synergistically modulated during walking to facilitate ongoing movement. PMID:22190317

Makihara, Yukiko; Segal, Richard L.; Wolpaw, Jonathan R.; Thompson, Aiko K.

2011-01-01

235

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

PubMed Central

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

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

2004-01-01

236

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

PubMed

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

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

2015-01-21

237

Rapid motor learning in the translational vestibulo-ocular reflex  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

238

Modification of Otolith Reflex Asymmetries Following Space Flight  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

239

Agmatine disrupts prepulse inhibition of acoustic startle reflex in rats.  

PubMed

Agmatine is a guanidine-amine formed by the enzymatic decarboxylation of arginine. Agmatine has been proposed to be a neuromodulator and its downstream derivatives, the polyamines, have been suggested to be responsible for sensory gating deficits seen in schizophrenia. In this study, male Wistar rats underwent treatments with agmatine, vehicle or other agents known to alter sensory gating in an experimental paradigm of prepulse inhibition (PPI) of the acoustic startle response. Apomorphine (1 mg/kg s.c.), a nonselective dopamine agonist known to disrupt PPI responses, was injected as the positive reference. Neither apomorphine nor agmatine (40-160 mg/kg i.p.) induced effects on the intensity of startle reflex without a prepulse. However, apomorphine or agmatine (160 mg/kg i.p.) disrupted the PPI of acoustic startle reflex. Furthermore, when given 30 min prior, agmatine acted additively with apomorphine's effect on PPI. In an attempt to gain more insight, haloperidol (1 and 2 mg/kg i.p.), clozapine (2.5-7.5 mg/kg i.p.) or quetiapine (2.5 and 7.5 mg/kg i.p.) was also injected prior to agmatine (160 mg/kg i.p.). Haloperidol (1 mg/kg) and clozapine (2.5 and 5 mg/kg) were able to prevent the PPI-disrupting effects of apomorphine. However, none of these antipsychotics prevent the PPI-disrupting effects of agmatine. These results suggest that agmatine disrupts the PPI of acoustic startle reflex of rats in a fundamentally different manner than apomorphine does. It may also have a critical role in the pathogenesis of sensorimotor gating-related dysfunctions. PMID:19282421

Uzbay, T; Kayir, H; Goktalay, G; Yildirim, M

2010-06-01

240

The reflex-diode HPM source on Aurora  

SciTech Connect

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.

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

1990-06-01

241

Abnormal pupillary light reflex with chromatic pupillometry in Gaucher disease  

PubMed Central

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

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

2014-01-01

242

Abnormal pupillary light reflex with chromatic pupillometry in Gaucher disease.  

PubMed

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

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

2014-02-01

243

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

PubMed Central

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

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

2014-01-01

244

In Proceedings AISB 2006 Symposium on Integrative Approaches to Machine Consciousness Towards a Computational Account of Reflexive Consciousness  

E-print Network

In Proceedings AISB 2006 Symposium on Integrative Approaches to Machine Consciousness Towards a Computational Account of Reflexive Consciousness Murray Shanahan Department of Computing, Imperial College a preliminary sketch for an account of reflexive consciousness based on an im- plemented architecture

Shanahan, Murray

245

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

E-print Network

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

Paris-Sud XI, Université de

246

Mechanisms of the clasp-knife reflex studied in an animal model  

Microsoft Academic Search

Summary The mechanisms of the clasp-knife reflex were studied in the soleus muscle of an animal model, the decerebrate cat with a dorsal hemisection of the lower thoracic cord. The reflex is shown to be autogenetic, and to depend on muscle length in keeping with previous suggestions. However, the magnitude of the inhibition increases with increasing initial force, and the

W. Z. Rymer; J. C. Houk; P. E. Crago

1979-01-01

247

Clifford Geertz and Beyond: The Interpretive Interview/Essay and Reflexive Ethnography.  

ERIC Educational Resources Information Center

In "The Uses of Diversity," the interpretive anthropologist, Clifford Geertz, says that it is impossible to completely get inside the point of view of another culture. Geertz contends, however, that despite multiple voices in the growing body of reflexive ethnographies there is still an author composing the work. Besides Geertz, reflexive

Page, Miriam Dempsey

248

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

PubMed

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

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

2013-05-01

249

EMG feedback tasks reduce reflexive stiffness during force and position perturbations.  

PubMed

Force and position perturbations are widely applied to identify muscular and reflexive contributions to posture maintenance of the arm. Both task instruction (force vs. position) and the inherently linked perturbation type (i.e., force perturbations-position task and position perturbations-force tasks) affect these contributions and their mutual balance. The goal of this study is to explore the modulation of muscular and reflexive contributions in shoulder muscles using EMG biofeedback. The EMG biofeedback provides a harmonized task instruction to facilitate the investigation of perturbation type effects irrespective of task instruction. External continuous force and position perturbations with a bandwidth of 0.5-20 Hz were applied at the hand while subjects maintained prescribed constant levels of muscular co-activation using visual feedback of an EMG biofeedback signal. Joint admittance and reflexive impedance were identified in the frequency domain, and parametric identification separated intrinsic muscular and reflexive feedback properties. In tests with EMG biofeedback, perturbation type (position and force) had no effect on joint admittance and reflexive impedance, indicating task as the dominant factor. A reduction in muscular and reflexive stiffness was observed when performing the EMG biofeedback task relative to the position task. Reflexive position feedback was effectively suppressed during the equivalent EMG biofeedback task, while velocity and acceleration feedback were both decreased by approximately 37%. This indicates that force perturbations with position tasks are a more effective paradigm to investigate complete dynamic motor control of the arm, while EMG tasks tend to reduce the reflexive contribution. PMID:21717098

Forbes, Patrick A; Happee, Riender; van der Helm, Frans C T; Schouten, Alfred C

2011-08-01

250

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

ERIC Educational Resources Information Center

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…

Day, Jessica E.; Feeney, M. Patrick

2008-01-01

251

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

Microsoft Academic Search

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

Sara Delamont

2009-01-01

252

Effects of fixation and optokinetic stimulation on vestibulo-ocular reflex suppression.  

PubMed Central

Suppression of the vestibulo-ocular reflex was assessed in normal subjects and patients with neurological disorders to determine the relative effects on suppression of a single fixation target and an optokinetic field. Subjects were rotated sinusoidally in yaw at varying frequencies of up to 0.5 Hz whilst seated in a Barany chair. A comparison was made between eye movements in darkness, those produced during fixation on a central target mounted to the chair, and eye movements during fixation on the target plus an "earth-fixed" or "chair-fixed" visual background. Presentation of a background produced only minimal effects on the suppression of the vestibulo-ocular reflex in normal subjects. In patients with impairment of fixation suppression, suppression of the vestibulo-ocular reflex was not improved after presentation of either form of optokinetic field. The results demonstrate that central fixation is the predominant requirement for suppression of the vestibulo-ocular reflex. This correlates closely with the ability to pursue. Although the optokinetic reflex generates following eye movements similar to pursuit, it cannot be used to mediate suppression of the vestibulo-ocular reflex in the absence of an intact pursuit system. The findings strengthen the view that the optokinetic reflex evolved to act in synergy with the vestibulo-ocular reflex in generating compensatory eye movements. Images PMID:7175543

Chambers, B R; Gresty, M A

1982-01-01

253

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

ERIC Educational Resources Information Center

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

Medova, Lucie

2009-01-01

254

From CNI-1493 to the immunological homunculus: physiology of the inflammatory reflex  

Microsoft Academic Search

The inflammatory reflex is a neuro- physiological mechanism that regulates the im- mune system. The efferent branch of the reflex the cholinergic anti-inflammatory pathway, which in- hibits inflammation by suppressing cytokine syn- thesis via release of acetylcholine in organs of the reticuloendothelial system, including the spleen, liver, and gastrointestinal tract. Acetylcholine binds to 7 nicotinic acetylcholine receptors ex- pressed by

Stacey L. Oke; Kevin J. Tracey

2007-01-01

255

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

ERIC Educational Resources Information Center

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…

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

2009-01-01

256

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

ERIC Educational Resources Information Center

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…

McClean, Michael D.

1987-01-01

257

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

Microsoft Academic Search

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

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

2005-01-01

258

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

ERIC Educational Resources Information Center

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…

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

2010-01-01

259

Cocaine-induced genital reflexes during paradoxical sleep deprivation and recovery  

Microsoft Academic Search

Paradoxical sleep deprivation (PSD) for 96 h together with cocaine administration elicits genital reflexes (penile erection [PE] and ejaculation [EJ]) in rats. Our objective was to examine genital reflexes after periods of 24, 48, 72, 96, 120, and 144 h of PSD and during a 4-day recovery period in acute cocaine-administered rats. After 24 h of PSD followed by cocaine

Monica L. Andersen; Magda Bignotto; Sergio Tufik

2003-01-01

260

Criteria for reflex peripheral smear review in infants.  

PubMed

Criteria for peripheral smear review are designed to include those samples with results outside the reference interval and can be more extreme based on what is considered to have clinical utility. However, we are unaware of previous studies that reported the distributions of various complete blood cell count (CBC) parameters in infants. In the following study we reviewed screening CBC results of 692 infants aged 9-15 months in order to determine the proportion of peripheral smear reviews recommended according to consensus criteria and that after adjusting for the observed distributions of the various parameters. According to consensus criteria the recommended reflex peripheral smear review rate was 39.7% (95% CI 36.1-43.4) whereas after adjustment for the observed distributions, the rate fell to 5.6% (95% CI 3.9-7.3) (p < 0.001). The major reasons for the difference in rates were the high proportion of infants with an absolute lymphocyte count > 7 × 10(9)/L (17.5%), the presence of a plus one blast flag (4.3%), and a large unstained cell count of ? 5% (26.2%) (equivalent to + 1 atypical flag). We found that international consensus criteria for reflex peripheral smear review results in a very high peripheral smear review rate in well infants, and might be inappropriate. PMID:24650178

Froom, Paul; Isakov, Elada; Barak, Mira

2014-06-01

261

Vestibulospinal control of reflex and voluntary head movement  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

262

Reflex effects on the heart of stimulating left atrial receptors  

PubMed Central

1. Stimulation of left atrial receptors, by distension of the pulmonary vein/left atrial junctions, is known to cause a reflex increase in heart rate; the efferent pathway is known to be solely in the sympathetic nerves. 2. In expectation of a concomitant positive inotropic response the effect of stimulating the left atrial receptors on the inotropic state of the left ventricle was studied, using as a known sensitive index of inotropic changes the maximal rate of rise of pressure in the left ventricle (dP/dt max). 3. Stimulation of left atrial receptors resulted in an increase in heart rate but there were no significant concomitant changes in dP/dt max. 4. It is concluded that activity in this discrete efferent pathway does not include an inotropic effect on the left ventricle and therefore the reflex involves only those sympathetic nerves which innervate the sinu-atrial node. 5. The possible function of atrial receptors in the regulation of heart volumes is discussed. PMID:5124571

Furnival, C. M.; Linden, R. J.; Snow, H. M.

1971-01-01

263

Trigemino-cervical reflex in spinal cord injury.  

PubMed

Abnormal enhancement of polysynaptic brainstem reflexes has been previously reported in patients with spinal cord injury (SCI). We aimed to investigate trigemino-cervical reflex (TCR) in SCI since it may reflect alterations in the connections of trigeminal proprioceptive system and cervical motoneurons. Consecutive 14 patients with SCI and 16 healthy subjects were included in this study. All patients were in the chronic phase. TCR was recorded over sternocleidomastoid (SCM) and splenius capitis (SC) muscles by stimulation of infraorbital nerve. We measured onset latency, amplitudes and durations of responses and compared between groups. We obtained stable responses over both muscles after one sided stimulation in healthy volunteers whereas probability of TCR was decreased in patients over both SCM (78.6% vs. 100%, p=0.050) and SC (71.4% vs. 100%, p=0.022). The absence of TCR was related to use of oral baclofen (?50mg/day). However, when present, responses of SCI group had higher amplitudes and were more persistent. We demonstrated that TCR probability was similar to healthy subjects in SCI patients who used no or low dose oral baclofen. But it had higher amplitudes and longer durations. It was not obtained in only two patients who used oral baclofen more than 50mg/day. PMID:25128217

Gündüz, Ay?egül; Uzun, Nurten; Örnek, Nurettin ?rem; Ünalan, Halil; Karamehmeto?lu, ?afak Sahir; K?z?ltan, Meral E

2014-09-19

264

Activation of mu-opioid receptors in rat ventrolateral medulla selectively blocks baroreceptor reflexes while activation of delta opioid receptors blocks somato-sympathetic reflexes.  

PubMed

The effects of activation of mu and delta-opioid receptors in the rostral ventrolateral medulla (RVLM) on somato-sympathetic, baroreceptor and chemoreceptor reflexes, as well as respiratory rhythmicity in sympathetic nerves, were examined in urethane anaesthetized (1.1-1.2 g/kg) and artificially ventilated Sprague-Dawley rats. Microinjection of the delta-opioid receptor agonist [D-Pen(2,5)]-enkephalin (DPDPE; 8 mM, 50 nl) bilaterally into the RVLM potently inhibited the post-inspiratory-related burst discharges of lumbar sympathetic nerve activity (LSNA) but had only limited effects on splanchnic sympathetic nerve activity (SSNA) and phrenic nerve discharge. Injection of DPDPE into the RVLM strongly attenuated the somato-sympathetic reflex (approximately 50-80%) evoked in the lumbar sympathetic nerve and splanchnic sympathetic nerve by tibial nerve stimulation but had no effect on baroreceptor reflexes and chemoreceptor reflexes evoked by aortic nerve stimulation and brief hypoxia, respectively. Injection of the mu-opioid receptor agonist, [D-Ala(2),N-Me-Phe(4),Gly-ol(5)]-enkephalin (DAMGO; 4 mM, 50 nl), also elicited a greater inhibition of LSNA than SSNA accompanied by an abolition of phrenic nerve discharge. Injection of DAMGO inhibited the baroreceptor reflex without significant effect on either the somato-sympathetic or the chemoreceptor reflexes. We propose that opioid peptides diminish specific excitatory and inhibitory inputs to the presympathetic neurons in RVLM via distinct presynaptic receptor subclasses. PMID:11784705

Miyawaki, T; Goodchild, A K; Pilowsky, P M

2002-01-01

265

Difference in the amplitude of the human soleus H reflex during walking and running.  

PubMed Central

1. The Hoffman reflex, or H reflex, was strongly modulated in the human soleus muscle during both walking (4 km/h) and running (8 km/h). It was relatively low at the time of heel contact, increased progressively during the stance phase, and reached its maximum amplitude late in the stance phase. During ankle dorsiflexion the H reflex was absent. 2. During running the peak e.m.g. level of the soleus was on average 2.4 times higher than during walking but the maximum amplitude of the H reflex was never larger than during walking. In fact, the H reflex was on average significantly (P less than 0.05 for one-tailed t test) smaller during running than during walking. Furthermore, the slope of the least-squares line fitted to the relation between the H reflex amplitude and the background e.m.g. was always steeper for the walking data than for the running data. 3. The difference in the H reflex in the two tasks is evidence that the size of the H reflex is not simply a passive consequence of the alpha-motoneurone excitation level, as indicated by the e.m.g., but is also influenced by other central neural mechanisms. We suggest that presynaptic inhibition is the most likely mechanism accounting for the change in the slope. 4. The modulation of the reflexes during walking and running can be interpreted in terms of the idea of automatic gain compensation. The decreased gain during running may be appropriate to reduce saturation of motor output and potential instability of the stretch reflex feed-back loop. PMID:3446790

Capaday, C; Stein, R B

1987-01-01

266

The effects of morphine on supraspinal and propriospinal somatocardiac reflexes in anesthetized rats.  

PubMed

In anesthetized rats, the effects of i.v. injection of morphine on supraspinally- and spinally-mediated tachycardiac reflex responses of heart rate (HR) and cardiac sympathetic nerve reflex activity were examined following electrical stimulation of either a non-segmental hindlimb (tibial) or a segmental (3rd or 4th intercostal, IC3-4) afferent nerve. In central nervous system (CNS)-intact rats, the supraspinally-mediated reflex increase in HR in response to tibial afferent nerve stimulation was augmented by morphine, whereas the increase in response to IC3-4 afferent nerve stimulation was variable. Both the supraspinally-mediated myelinated (A) and unmyelinated (C) reflex discharges in the cardiac sympathetic nerve elicited by tibial afferent nerve stimulation were augmented by morphine. The effects of morphine on A- and C-sympathetic reflex discharges elicited by IC3-4 afferent nerve stimulation varied depending upon whether the discharge was of supraspinal or spinal origin. In spinal rats (spinalized at the cervical level), tibial afferent nerve stimulation did not produce any HR response, whereas IC3-4 afferent nerve stimulation produced a reflex increase in both HR and sympathetic reflex discharges of spinal origin. Furthermore, these spinal HR and sympathetic nerve reflex responses were inhibited by morphine. In conclusion, morphine depressed somatocardiac sympathetic reflexes at the spinal level, but enhanced these reflexes at the supraspinal level, leading to different effects of morphine on somatically-induced HR responses of supraspinal and spinal origins depending upon the segmental levels of afferent nerves stimulated. PMID:10454157

Uchida, S; Suzuki, A; Hotta, H; Sato, A

1999-07-16

267

Good airway reflexes and normal sensorium do not assure safe tracheal extubation in patients with cerebral hemispheric pathology.  

PubMed

Following brain injury, return of consciousness and cough reflex are presumed to be associated with safe airway. We describe two patients who had a normal cough reflex, but impaired swallowing, which led to prolonged hospital stay. This report highlights the dissociation between the cough reflex and swallowing function in such patients. PMID:21899382

Sriganesh, Kamath; Smita, Vimala; Bansal, Sonia; Rao, G S Umamaheswara

2012-02-01

268

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

269

Kinesio taping in young healthy subjects does not affect postural reflex reactions and anticipatory postural adjustments of the trunk: a pilot study.  

PubMed

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

Voglar, Matej; Sarabon, Nejc

2014-09-01

270

Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

271

Developmental tuning of reflexive attentional effect to biological motion cues  

PubMed Central

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

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

2014-01-01

272

Developmental tuning of reflexive attentional effect to biological motion cues.  

PubMed

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

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

2014-01-01

273

Effect of brotizolam on the averaged photopalpebral reflex in man  

PubMed Central

1 The photopalpebral reflex (PPR) is a useful method to assess level of arousal. Healthy males were given either brotizolam (0.0625, 0.125, 0.25 or 0.5 mg) or placebo within a double-blind, crossover design. Changes in PPR and subjective assessments were observed for 5 h after medication. 2 Prolongation of the latencies of PPR were dose dependent, and the amplitude tended to be reduced. These effects appeared within 30 min, and lasted about 4 h. 3 The dose-response curve of the maximum prolongation of the latencies was linear. 4 Sleepiness and slight ataxia were observed after drug ingestion. Sleepiness was correlated with the prolongation of the PPR latencies. 5 Brotizolam could be a potent hypnotic, with rapid onset and moderate duration of action, and it has no severe side-effects. PMID:6661378

Tanaka, M.; Isozaki, H.; Mizuki, Y.; Inanaga, K.

1983-01-01

274

A procedure concept for local reflex control of grasping  

NASA Technical Reports Server (NTRS)

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

Fiorini, Paolo; Chang, Jeffrey

1989-01-01

275

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

PubMed

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

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

2015-02-01

276

Analgesic-antiinflammatory drugs inhibit orbicularis oculi reflexes in humans via a central mode of action.  

PubMed

1. A cross-over single blind study examined the possible central effects of non-opioid analgesic drugs on the trigeminal reflexes. 2. The corneal reflex and blink reflex (R1, R2) were recorded electromyographically and response areas measured in healthy volunteers before and after intramuscular injection of piroxicam (40 mg); and after intravenous injection of lysine acetylsalicylate (500 mg). After the last drug recording the subjects received intravenous naloxone (2 mg) followed 5 minutes later by further reflex testing. Saline was used as a placebo in control experiments. 3. Both analgesics reduced the corneal reflex: piroxicam induced a 27% and lysine acetylsalicylate a 21% a reduction that naloxone did not reverse. Neither drug reduced the early or the late component of the blink reflex. 4. The marked inhibitory changes that the two non-narcotic analgesics produced on the corneal reflex--a nociceptive response--indicate a centrally-mediated action. 5. Naloxone's failure to reverse the induced analgesia argues against opiate receptor mediation. PMID:8115666

Ferracuti, S; Leardi, M G; Cruccu, G; Fabbri, A; Itil, T M

1994-01-01

277

Systemic hypoxia facilitates somato-cardiac sympathetic A- and C-reflexes in anesthetized rats.  

PubMed

In rats anesthetized with urethane, electrical stimuli applied to tibial nerve afferents produced a somato-sympathetic A-reflex of 41 +/- 2 (mean +/- SEM)ms latency and C-reflex of 210 +/- 13 ms latency recorded in the left inferior cardiac sympathetic nerve. Hypoxia was induced by switching room air to nitrogen/oxygen gas mixture in the inspiratory line reducing end-tidal oxygen from about 18% FETO2 to 10% FETO2 and 6% FETO2 for 60s, respectively. During 6% FETO2 hypoxia, the amplitude of the somato-cardiac sympathetic A-reflex increased significantly to 138 +/- 13% of the control, and that of the C-reflex increased to 186 +/- 18% of the control. During 10% FETO2 hypoxia, the A-reflex increased insignificantly to 117 +/- 8%; the amplitude of the C-reflex was augmented significantly to 149 +/- 11% of the control. Peripheral carotid chemoreceptor denervation abolished the facilitatory effects of systemic hypoxia. It is concluded that carotid chemoreceptor stimulation enhances the responsiveness of somato-cardiac sympathetic excitatory reflexes originating in the hind limb receptors. PMID:8897486

Li, W M; Sato, A; Suzuki, A; Trzebski, A

1996-10-01

278

Modulation of somatocardiac sympathetic reflexes mediated by opioid receptors at the spinal and brainstem level.  

PubMed

Modulation of somatosympathetic reflexes at the spinal cord and the brainstem was studied by administering opioid receptor agonists into the intrathecal space of the lumbar spinal cord and into the subarachnoid space of the cisterna magna in rats anesthetized with alpha-chloralose and urethane. Somatocardiac sympathetic A- and C-reflexes were elicited by electrical stimulation of myelinated (A) and unmyelinated (C) afferent fibers of the tibial nerve, respectively. Intrathecal administration of the mu-opioid receptor agonist DAMGO selectively depressed the C-reflex in a dose-dependent manner (minimum effective dose 10 ng), whereas the intrathecal injection of the delta-opioid receptor agonist DPDPE and the kappa-opioid receptor agonist U-50,488H only at doses of 10 micrograms and 100 micrograms, respectively, led to a significant depression of the C-reflex. Injection of DAMGO into the cisterna magna enhanced both A- and C-reflexes in a dose-dependent manner (minimum effective dose 1 ng). The administration of neither DPDPE nor U-50,488H into the cisterna magna affected A- or C-reflexes. It is concluded that the activation of mu-opioid receptors is mainly or exclusively responsible for suppressing somatosympathetic C-reflexes at the spinal cord and for enhancing them at the brainstem. PMID:7589306

Sato, A; Sato, Y; Schmidt, R F

1995-01-01

279

Laryngopharyngeal sensory discrimination testing and the laryngeal adductor reflex.  

PubMed

Laryngopharyngeal sensory capacity has been determined by endoscopically administering air pulse stimuli to the mucosa innervated by the superior laryngeal nerve and asking the patient if he or she feels the stimulus. A potential shortcoming of this psychophysical testing (PT) procedure is that it is a subjective test, and patients with impaired cognition may not be able to perform the required task. In the search for an objective measure of laryngeal sensory function, we have observed that the laryngeal adductor reflex (LAR) is evoked at stimulus intensities similar to those capable of eliciting the psychophysical, or perceptual, response. The purpose of this study is to determine if the threshold for eliciting the LAR is the same as that of the sensory threshold. A specially designed endoscope was used to present air pulse stimuli (range 0.0 to 10 mm Hg) to the laryngopharynx in 20 healthy subjects and in 80 patients with dysphagia, using both PT and the LAR. The patients had a variety of underlying diagnoses, with stroke and chronic neurologic disease predominating (n = 65). In the control group and in the group of patients with dysphagia, there was no statistically significant difference between the median laryngopharyngeal sensory thresholds whether we used PT or the LAR (p>.05, Wilcoxon signed-rank test). The intraclass correlation for the total sample was .999 (U = .999, L = .998). Since psychophysical and sensorimotor reflex thresholds were not statistically significantly different and the intraclass correlation was close to a perfect correlation, we conclude that the LAR can be used as an objective and accurate clinical method of endoscopically assessing laryngopharyngeal sensory capacity. PMID:10453777

Aviv, J E; Martin, J H; Kim, T; Sacco, R L; Thomson, J E; Diamond, B; Close, L G

1999-08-01

280

Cough reflex sensitivity in adolescents with diabetic autonomic neuropathy  

PubMed Central

Objective Diabetic autonomic neuropathy (DAN) is one of the chronic complications of diabetes mellitus which can involve one or more organ systems. DAN without apparent symptoms is more often in childhood and adolescence. While heart rate variability (HRV) and Ewing's battery of cardiovascular tests are regarded as a gold standard for the diagnosis of DAN, the examination of cough reflex sensitivity (CRS) is another possibility. The aim of this study was to compare HRV and CRS in children with diabetes mellitus. Materials and methods Sixty one patients (37 girls, 24 boys) aged 15-19 suffering from diabetes mellitus type 1 completed the study. Based on HRV, patients were divided into 2 groups - with DAN (n = 25) and without DAN (n = 32), 4 patients were excluded because of ambiguous results. CRS was studied in each patient by inhalation of gradually increasing concentration of capsaicin. Results Subjects with DAN required a significantly higher concentration of capsaicin needed to evoke 2 coughs (median 625 ?mol/l, IQR 68.4-625.0 ?mol/l vs. median 29.3 ?mol/l, IQR 9.8-156.3 ?mol/l, P < 0.001) and 5 coughs (median 2500.0 ?mol/l, IQR 1250.0-2500.0 ?mol/l vs. median 312.5 ?mol/l, IQR 117.2-625.0 ?mol/l, P < 0.001) compared with those without DAN. Moreover, a strong negative correlation between HRV and CRS was established. Conclusion Diabetes mellitus lowers the cough response. Cough reflex sensitivity appears to be another sensitive method for the evaluation of DAN in diabetes. PMID:20156724

2009-01-01

281

Electrophysiological study of the bulbocavernosus reflex: normative data  

PubMed Central

Summary In the clinical setting the bulbocavernosus reflex (BCR) is elicited by squeezing the glans penis and digitally palpating the contraction of the bulbocavernosus (BC) muscle. In neurophysiology the BCR is obtained by stimulating the dorsal nerve of the penis or clitoris and by recording the response from BC muscle and it should be performed in selected patients with suspected urinary, bowel, or sexual neurogenic dysfunction. The BCR is considered one of the sacral neurophysiological tests of the greatest clinical utility. Previous normative data were obtained on small samples. The aim of this study was to determine normative values for the BCR in a large sample of men. We studied a large population (105 men; mean age 53 years, range 19–73 years) without central or peripheral neurological diseases. In each subject the sacral reflex was elicited by electrical stimulation of the base of the dorsum penis and recorded using a surface electrode from the BC muscle. We recorded the latency, calculated at onset, and the maximal amplitude of response, calculated peak to peak. We were able to detect the BCR in all the men. No correlation between BCR latency and age was found (r=0.136; p=0.160). The mean onset latency value was 33.0±4.85 ms (mean±2SD, range 26.8–39.4). The mean amplitude value was 16.53±12.21 ?V (mean±2SD, range 4.2–43.6). Our normative data on the BCR were similar to previously published data. PMID:24598398

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

2013-01-01

282

Acupuncture stimulation inhibits somato-renal sympathetic A- and C-reflexes in anesthetized rats.  

PubMed

Stimulation of peripheral nerve afferent for example tibial nerve by a strong electrical stimulation (rectanfular wave with 20V amplitude; pulse duration of 0.5 ms, 0.3 pulses/sec) can evoke a discharge of the somato-sympathetic reflex which is recorded on the efferent of renal sympathetic nerve. The component of the somato-sympathetic reflex can be divided into two parts: one is related to the transmission of the myelinated afferent fibers with a short lantency (41+/-2 ms) and is defined A-reflex, the other is related to the transmission of the unmyelinated afferent fibers with a long latency (210+/-13 ms) and is defined C-reflex. In the present study, an acupuncture needle (diameter 0.34 mm) was inserted into the hind limbs of the rat, dorsolaterally at the area of acupoint: huantiao (GB30), at a depth of 4-5 mm and was twisted right and left twice every second during recording the somato-renal sympathetic reflex. It was found that acupuncture on the huantiao acupoint significantly inhibited both A- and C-reflexes. There was no different inhibition of the A- and C-reflexes by acupuncture on the right or left side. However acupuncture on the fore limbs of the rat dorsolaterally at the area of acupoint: quchi (LI11) showed no effect on neither A- nor C-reflexes. These results suggest that acupuncture at the same spinal segment of the acupoint inhibits the somatorenal sympathetic reflex. PMID:12269720

Li, Wei-Min; Wu, Gen-Cheng; Arita, Hideko; Hanaoka, Kazuo

2002-01-01

283

Trunk Muscle Reflex Amplitudes Increased in Patients With Subacute, Recurrent LBP Treated With a 10-Week Stabilization Exercise Program  

PubMed Central

Altered trunk muscle reflexes have been observed in patients with low back pain (LBP). Altered reflexes may contribute to impaired postural control, and possibly recurrence of LBP. Specific stabilization exercise (SSE) programs have been shown to decrease the risk of LBP recurrence in a select group of patients with acute, first episode LBP. It is not known if trunk muscle reflex responses improve with resolution of subacute, recurrent LBP when treated with a SSE program. A perturbation test was used to compare trunk muscle reflexes in patients with subacute, recurrent LBP, before and after 10 weeks of a SSE program and a group of matched control subjects (CNTL). The LBP group pre therapy had delayed trunk muscle reflexes compared with the CNTL group. Post therapy reflex latencies remained delayed, but amplitudes increased. Increased reflex amplitudes could limit excessive movement of the spine when perturbed; potentially helping prevent recurrence. PMID:22964879

Navalgund, Anand; Buford, John A.; Briggs, Mathew S.; Givens, Deborah L.

2013-01-01

284

From CNI-1493 to the immunological homunculus: physiology of the inflammatory reflex.  

PubMed

The inflammatory reflex is a neurophysiological mechanism that regulates the immune system. The efferent branch of the reflex the cholinergic anti-inflammatory pathway, which inhibits inflammation by suppressing cytokine synthesis via release of acetylcholine in organs of the reticuloendothelial system, including the spleen, liver, and gastrointestinal tract. Acetylcholine binds to alpha7 nicotinic acetylcholine receptors expressed by macrophages and other cytokine-producing cells. Receptor-ligand engagement suppresses proinflammatory cytokines and prevents tissue damage. Herein is a review of some of the experimental studies that define the inflammatory reflex and its anatomic and physiologic components. PMID:18065685

Oke, Stacey L; Tracey, Kevin J

2008-03-01

285

Modulation of the human nociceptive flexion reflex by pleasant and unpleasant odors.  

PubMed

The nociceptive withdrawal reflex (NWR), a defensive response that allows withdrawal from a noxious stimulus, is a reliable index of spinal nociception in humans. It has been shown that various kinds of stimuli (emotional, visual, auditory) can modulate the transmission and perception of pain. The aim of the present study was to evaluate, by means of the NWR, the modulatory effect on the spinal circuitry of olfactory stimuli with different emotional valence. The magnitude of the NWR elicited by electrical stimulation of the sural nerve was measured while 18 subjects (9 women, 9 men) smelled pleasant, unpleasant, or neutral odors. The NWR was conditioned by odor probe with interstimulus intervals (ISIs) of 500 ms and 1,500 ms. The magnitude of NWR was significantly greater after the unpleasant odor probe (P <.001) and reduced following the pleasant odor probe (P<.001) at both ISIs. A significant effect of olfactory stimuli on subjective pain ratings were found at both ISIs for pleasant vs unpleasant odors (P<.000), and for both pleasant and unpleasant odors vs neutral and basal conditions (P<.000). No statistical differences in subjective pain ratings at different ISIs were found. Consistent with the notion that NWR magnitude and pain perception can be modulated by stimuli with different emotional valence, these results show that olfactory stimuli, too, can modulate spinal nociception in humans. PMID:24040974

Bartolo, Michelangelo; Serrao, Mariano; Gamgebeli, Zurab; Alpaidze, Marina; Perrotta, Armando; Padua, Luca; Pierelli, Francesco; Nappi, Giuseppe; Sandrini, Giorgio

2013-10-01

286

Comparison between the effects of lisinopril and losartan on the cougn reflex in anesthetized and awake rabbits.  

PubMed

The aim of the present study was to analyze differences in cough induction between losartan and lisinopril in both anaesthetized and awake rabbits, i.e., under conditions in which the influences of higher brain areas on the cough reflex are strongly reduced or abolished. Losartan (500 ?g/kg), lisinopril (100 ?g/kg) and NaCl 0.9% saline solution (vehicle) were administered by intravenous injections. Animals were randomly assigned to the different experimental treatments. The cough reflex was induced by chemical (citric acid) and/or mechanical stimulation of the tracheobronchial tree. In anaesthetized rabbits, losartan and lisinopril caused similar hypotensive effects. Lisinopril, but not losartan, increased the cough response induced by both mechanical and chemical stimulation due to increases in the cough number, i.e. the number of coughs induced by each stimulation challenge. In awake animals, only lisinopril significantly increased the cough number. The results support the notion that cough potentiation induced by losartan, and possibly other sartans, is lower than that induced by most angiotensin-converting enzyme inhibitors despite the reduction or complete absence of higher brain functions. In this connection, the comparison between present results and our previous findings on ramipril and zofenopril shows that losartan and zofenopril display similar cough-inducing potency, much lower than that of lisinopril and ramipril. PMID:23756395

Mutolo, D; Cinelli, E; Bongianni, F; Evangelista, S; Pantaleo, T

2013-04-01

287

REFLEX MODIFICATION AND THE DETECTION OF TOXICANT-INDUCED AUDITORY DYSFUNCTION  

EPA Science Inventory

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

288

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

PubMed Central

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

Gibson, Peter G.; Birring, Surinder S.

2014-01-01

289

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

NASA Technical Reports Server (NTRS)

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

Highstein, S. M.

1998-01-01

290

Trigemino-Cardiac Reflex During Orbital Floor Reconstruction: A Case Report and Review  

Microsoft Academic Search

Trigemino-cardiac reflex is occurrence of hypotension and bradycardia upon surgical manipulation of areas supplied by the\\u000a trigeminal nerve, and has been reported during craniofacial maxillofacial and ocular surgeries. Communication between the\\u000a anaesthetic and surgical team is essential, and cessation of the precipitating stimulus is the first and most important therapeutic\\u000a step. We report a case of immediate, reproducible, and reflexive

Sunil VasudevK; K. Sudhakara Reddy

291

Reflex: intramolecular barcoding of long-range PCR products for sequencing multiple pooled DNAs  

PubMed Central

We present an intramolecular reaction, Reflex™, to derive shorter, sequencer-ready, daughter polymerase chain reaction products from a pooled population of barcoded long-range polymerase chain reaction products, whilst still preserving the cognate DNA barcodes. Our Reflex workflow needs only a small number of primer extension steps to rapidly enable uniform sequence coverage of long contiguous sequence targets in large numbers of samples at low cost on desktop next-generation sequencers. PMID:23580546

Casbon, James A.; Slatter, Andrew F.; Musgrave-Brown, Esther; Osborne, Robert J.; Lichtenstein, Conrad P.; Brenner, Sydney

2013-01-01

292

Differences in H-reflex between athletes trained for explosive contractions and non-trained subjects  

Microsoft Academic Search

Summary  The efficacy of type la synapse on alpha-motoneurons of soleus and lateral gastrocnemius muscles has been investigated, using the H-reflex technique, in athletes engaged in sports requiring very rapid and intense contractions (sprinters and volley-ball players) as well as in non-trained subjects. It has been observed, in both muscles, that the ratio between the mean value of the maximal reflex

A. Casabona; M. C. Polizzi; V. Perciavalle

1990-01-01

293

Measurement of a single tendon reflex in conjunction with a myogram - The second manned Skylab mission  

NASA Technical Reports Server (NTRS)

A generalized hyperreflexia was observed in Skylab 2 crew members immediately postflight. Duration of the Achilles reflex was significantly shortened. Further shortening was observed on the fourth day after recovery. At the 16th and 29th postrecovery days a lengthening of the reflex was observed in two of the three crew members. The muscle potential intervals were shortened immediately postflight and remained shortened throughout the 29 day postflight evaluation period.

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

1976-01-01

294

Sleep deprivation disrupts prepulse inhibition of the startle reflex: reversal by antipsychotic drugs  

E-print Network

KU ScholarWorks | http://kuscholarworks.ku.edu Sleep deprivation disrupts prepulse inhibition of the startle reflex: reversal by antipsychotic drugs by Roberto Frau et al. KU ScholarWorks is a service provided by the KU Libraries’ Office... prepulse inhibition of the startle reflex: reversal by antipsychotic drugs. International Journal of Neuropsychopharmacology 11:947-955. Published version: http://www.dx.doi.org/10.1017/ S1461145708008900 Terms of Use: http://www2.ku...

Frau, Roberto; Orrù , Marco; Puligheddu, Monica; Gessa, Gian Luigi; Mereu, Giampaolo; Marrosu, Francesco; Bortolato, Marco

2008-11-01

295

Effect of Nicotine Upon the Reflex Action of Some Cutaneous Sense Organs in the Frog  

E-print Network

EFFECT OF NICOTINE UPON THE REFLEX ACTION OF SOIffi CUTANEOUS SENSE ORGANS IN THE FROG By Irene Howat 1914 A Thesis submitted to the Physiology Department and to the Faculty of the Graduate School of the University of Kansas in partial... of Kansas) The "basis of this investigation was to determine the effect of nicotine upon certain skin reflexes in the frog: to determine the duration of this effect; its after effect; if immunity could "be established; and how the action of nicotine...

Howat, Irene

1914-01-01

296

Enhanced sympathetic activity and cardiac sympathetic afferent reflex in rats with heart failure induced by adriamycin  

PubMed Central

Our previous studies have shown that the cardiac sympathetic afferent reflex is enhanced in rats with chronic heart failure (CHF) induced by coronary artery ligation and contributes to the over-excitation of sympathetic activity. We sought to determine whether sympathetic activity and cardiac sympathetic afferent reflex were enhanced in adriamycin-induced CHF and whether angiotensin II (Ang II) in the paraventricular nucleus (PVN) was involved in enhancing sympathetic activity and cardiac sympathetic afferent reflex. Heart failure was induced by intraperitoneal injection of adriamycin for six times during 2 weeks (15 mg/kg). Six weeks after the first injection, the rats underwent anesthesia with urethane and ?-chloralose. After vagotomy and baroreceptor denervation, cardiac sympathetic afferent reflex was evaluated by renal sympathetic nerve activity and mean arterial pressure (MAP) response to epicardial application of capsaicin (1.0 nmol). The response of MAP to ganglionic blockade with hexamethonium in conscious rats was performed to evaluate sympathetic activity. The renal sympathetic nerve activity and cardiac sympathetic afferent reflex were enhanced in adriamycin rats and the maximum depressor response of MAP induced by hexamethonium was significantly greater in adriamycin rats than that in control rats. Bilateral PVN microinjection of angiotensin II (Ang II) caused larger responses of the cardiac sympathetic afferent reflex, baseline renal sympathetic nerve activity and MAP in adriamycin rats than control rats. These results indicated that both sympathetic activity and cardiac sympathetic afferent reflex were enhanced and Ang II in the PVN was involved in the enhanced sympathetic activity and cardiac sympathetic afferent reflex in rats with adriamycin-induced heart failure. PMID:23554781

Zhang, Shujuan; Zhang, Feng; Sun, Haijian; Zhou, Yebo; Han, Ying

2012-01-01

297

The effect of sex and chronic low back pain on back muscle reflex responses.  

PubMed

Different back muscle reflex assessment protocols have shown abnormally longer reflex latency responses of back muscles in chronic low back pain (CLBP). However, many confounding variables are difficult to control, such as the load magnitude and the preactivation of trunk muscles. The aims of this study were to evaluate, in 30 subjects with CLBP and 30 healthy controls, the activation levels of back muscles during pre-loading and their reflex responses to sudden loading. After subjected to six practice perturbations, 20 sudden and unexpected forward perturbations of the trunk were applied in 30 CLBP subjects (14 women) and 31 controls (17 women), while attempting to minimize the confounding effect of preactivation level and perturbation amplitude. Reflex latency and amplitudes were computed from the surface EMG signals of four back muscles (bilaterally at L5, L3, L1, T10 vertebral levels). EMG was also collected from abdominal muscles. Subjects with CLBP significantly increased the preactivation of back muscles (abdominal preactivation the same) relative to controls while no sex effect was observed. While adjusting statistically for these differences, reflex amplitude was significantly higher in subjects with CLBP and men, compared to healthy controls and women, respectively. Interestingly, contrary to most of the literature available, no between-group effects were detected for reflex latency, which could potentially be explained by an appropriate control of confounding variables, but this remains to be clarified in future research. PMID:20174929

Larivière, Christian; Forget, Robert; Vadeboncoeur, Roger; Bilodeau, Martin; Mecheri, Hakim

2010-07-01

298

Stability of cough reflex sensitivity during viral upper respiratory tract infection (common cold).  

PubMed

Cough is among the symptoms most commonly associated with an acute, viral upper respiratory tract infection (URI), such as the common cold. Two previous studies incorporating capsaicin cough challenge methodology have demonstrated that cough reflex sensitivity is transiently enhanced during URI. These studies used single measurements of cough reflex sensitivity during the URI period. To our knowledge, no previous studies have included multiple measurements of cough reflex sensitivity to capsaicin during a URI to evaluate the stability of this measure during the acute viral illness. In the current methodological investigation, we performed capsaicin cough challenges in 42 subjects with URI who were otherwise healthy, adult, nonsmokers (25 female). Subjects were enrolled within 72 h of onset of illness and randomly assigned to 3 groups (n = 14 each) that underwent cough reflex sensitivity measurement (C2 and C5) at days 0 and 1 for group 1; days 2 and 3 for group 2; or days 4 and 5 for group 3. Each subject returned 4-8 weeks post-viral infection to establish a healthy baseline measurement (recovery). Our results support that cough reflex sensitivity to capsaicin, as measured by C5, is a sensitive measure that remains stable during 6 days of a URI. These results suggest that cough reflex sensitivity measures in the presence of a URI provide a sensitive and reproducible approach that could be used in future investigations seeking to test experimental antitussive therapies. PMID:24878421

Dicpinigaitis, Peter V; Tibb, Amit S; Ramsey, David L; Carr, Andrew N; Poore, Cathy L

2014-08-01

299

Proprioceptive neuropathy affects normalization of the H-reflex by exercise after spinal cord injury  

PubMed Central

The H-reflex habituates at relatively low frequency (10 Hz) stimulation in the intact spinal cord, but loss of descending inhibition resulting from spinal cord transection reduces this habituation. There is a return towards a normal pattern of low-frequency habituation in the reflex activity with cycling exercise of the affected hind limbs. This implies that repetitive passive stretching of the muscles in spinalized animals and the accompanying stimulation of large (Group I and II) proprioceptive fibers has modulatory effects on spinal cord reflexes after injury. To test this hypothesis, we induced pyridoxine neurotoxicity that preferentially affects large dorsal root ganglia neurons in intact and spinalized rats. Pyridoxine or saline injections were given twice daily (IP) for 6 weeks and half of the spinalized animals were subjected to cycling exercise during that period. After 6 weeks, the tibial nerve was stimulated electrically and recordings of M and H waves were made from interosseous muscles of the hind paw. Results show that pyridoxine treatment completely eliminated the H-reflex in spinal intact animals. In contrast, transection paired with pyridoxine treatment resulted in a reduction of the frequency-dependent habituation of the H-reflex that was not affected by exercise. These results indicate that normal Group I and II afferent input is critical to achieve exercise-based reversal of hyper-reflexia of the H-reflex after spinal cord injury. PMID:19913536

Ollivier-Lanvin, Karen; Keeler, Benjamin E.; Siegfried, Rachel; Houlé, John D.; Lemay, Michel A.

2009-01-01

300

Velocity-dependent suppression of the soleus H-reflex during robot-assisted passive stepping.  

PubMed

The amplitude of the Hoffmann (H)-reflex in the soleus (Sol) muscle is known to be suppressed during passive stepping compared with during passive standing. The reduction of the H-reflex is not due to load-related afferent inputs, but rather to movement-related afferent inputs from the lower limbs. To elucidate the underlying neural mechanisms of this inhibition, we investigated the effects of the stepping velocity on the Sol H-reflex during robot-assisted passive stepping in 11 healthy subjects. The Sol H-reflexes were recorded during passive standing and stepping at five stepping velocities (stride frequencies: 14, 21, 28, 35, and 42min(-1)) in the air. The Sol H-reflexes were significantly inhibited during passive stepping as compared with during passive standing, and reduced in size as the stepping velocity increased. These results indicate that the extent of H-reflex suppression increases with increasing movement-related afferent inputs from the lower limbs during passive stepping. The velocity dependence suggests that the Ia afferent inputs from lower-limb muscles around the hip and knee joints are most probably related to this inhibition. PMID:25449873

Masugi, Yohei; Kitamura, Taku; Kamibayashi, Kiyotaka; Ogawa, Tetsuya; Ogata, Toru; Kawashima, Noritaka; Nakazawa, Kimitaka

2015-01-01

301

Reflex Responsiveness of a Human Hand Muscle When Controlling Isometric Force and Joint Position  

PubMed Central

Objective This study compared reflex responsiveness of the first dorsal interosseus muscle during two tasks that employ different strategies to stabilize the finger while exerting the same net muscle torque. Methods Healthy human subjects performed two motor tasks that involved either pushing up against a rigid restraint to exert a constant isometric force equal to 20% of maximum, or maintaining a constant angle at the metacarpophalangeal joint while supporting an equivalent inertial load. Each task consisted of six 40-s contractions during which electrical and mechanical stimuli were delivered. Results The amplitude of short and long latency reflex responses to mechanical stretch did not differ significantly between tasks. In contrast, reflexes evoked by electrical stimulation were significantly greater when supporting the inertial load. Conclusions Agonist motor neurons exhibited heightened reflex responsiveness to synaptic input from heteronymous afferents when controlling the position of an inertial load. Task differences in the reflex response to electrical stimulation were not reflected in the response to mechanical perturbation, indicating a difference in the efficacy of the pathways that mediate these effects. Significance Results from this study suggest that modulation of spinal reflex pathways may contribute to differences in the control of force and position during isometric contractions of the first dorsal interosseus muscle. PMID:17646129

Maluf, Katrina S.; Barry, Benjamin K.; Riley, Zachary A.; Enoka, Roger M.

2007-01-01

302

A new method to determine reflex latency induced by high rate stimulation of the nervous system  

PubMed Central

High rate stimulations of the neuromuscular system, such as continuous whole body vibration, tonic vibration reflex and high frequency electrical stimulation, are used in the physiological research with an increasing interest. In these studies, the neuronal circuitries underlying the reflex responses remain unclear due to the problem of determining the exact reflex latencies. We present a novel “cumulated average method” to determine the reflex latency during high rate stimulation of the nervous system which was proven to be significantly more accurate than the classical method. The classical method, cumulant density analysis, reveals the relationship between the two synchronously recorded signals as a function of the lag between the signals. The comparison of new method with the classical technique and their relative accuracy was tested using a computer simulation. In the simulated signals the EMG response latency was constructed to be exactly 40 ms. The new method accurately indicated the value of the simulated reflex latency (40 ms). However, the classical method showed that the lag time between the simulated triggers and the simulated signals was 49 ms. Simulation results illustrated that the cumulated average method is a reliable and more accurate method compared with the classical method. We therefore suggest that the new cumulated average method is able to determine the high rate stimulation induced reflex latencies more accurately than the classical method. PMID:25100978

Karacan, Ilhan; Cakar, Halil I.; Sebik, Oguz; Yilmaz, Gizem; Cidem, Muharrem; Kara, Sadik; Türker, Kemal S.

2014-01-01

303

Cerebellar Substrates for Error Correction in Motor Conditioning  

Microsoft Academic Search

The authors evaluate a mapping of Rescorla and Wagner's (1972) behavioral model of classical conditioning onto the cerebellar substrates for motor reflex learning and illustrate how the limitations of the Rescorla-Wagner model are just as useful as its successes for guiding the development of new psychobiological theories of learning. They postulate that the inhibitory pathway that returns conditioned response information

Mark A. Gluck; M. Todd Allen; Catherine E. Myers; Richard F. Thompson

2001-01-01

304

Effects of reflex delays on postural control during unstable seated balance.  

PubMed

Patients with low-back pain (LBP) exhibit longer trunk muscle reflex latencies and poorer postural control than healthy individuals. We hypothesized that balance during a simulated postural control task would become impaired when the delays exhibited by LBP patients were incorporated into neuromuscular control. The task chosen for this investigation was seated balancing, which emphasizes trunk muscles' contribution in postural control. This task was modeled in Simulink as a fourth order linearized dynamic system with feedback delays. Optimization (minimizing error between experimental and model data) of state variables was used to determine neuromuscular control parameters. Experimental data were obtained from 7 subjects during 5 perturbation trials while balancing on the seat with eyes closed. Model accuracy, reflecting the ability of the model to capture the dynamics of seated balance, was correlated with seated balance performance (r=0.91, p<0.001). To minimize the risk of erroneous findings from inaccurate modeling, only the best five balancers' data were used for hypothesis testing. In these five subjects, feedback delays in modeled neuromuscular control were increased to determine their effect on task stability, trunk displacement and trunk moment. Simulations showed that longer delays found in LBP, in general, did not produce unstable balancing, but did result in increased trunk displacement (p<0.001) and trunk moment (p=0.001). This impairment in neuromuscular control in chronic LBP patients could possibly exacerbate their condition by increasing tissue strain (more spinal displacement) and stress (more spinal loading). PMID:19121523

Reeves, N Peter; Cholewicki, Jacek; Narendra, Kumpati S

2009-01-19

305

Cyclooxygenase-1 vs. cyclooxygenase-2 inhibitors in the induction of antinociception in rodent withdrawal reflexes.  

PubMed

Non-steroidal antiinflammatory drugs (NSAIDs) inhibit the cyclooxygenase (COX) enzyme and so they are effective analgesic, antiinflammatory and antipyretic drugs. The discovery of COX-2 led to the search for new NSAIDs with a selective action over this isoenzyme. The experiments performed to date have shown either more, less or no different efficacy of new COX-2 selective NSAIDs when compared to the non-selective inhibitors, probably because the comparison has not been performed under similar conditions. We have therefore compared the analgesic activity of six NSAIDs with different selectivity for the COX isoenzymes. The experiments were performed using the recording of spinal cord nociceptive reflexes in anaesthetised rats and in awake mice. The non-selective COX inhibitors, such as dexketoprofen trometamol, were effective in reducing nociceptive responses both in normal and monoarthritic rats (ED50s: 0.31 and 3.97 micromol/kg, respectively), and in mice with paw inflammation (12.5 micromol/kg, p < 0.01). The COX-1 selective inhibitor SC-58560 showed efficacy in normal rats (ED50: 0.8 micromol/kg) and in mice with paw inflammation (15 micromol/kg, p < 0.05), but not in monoarthritic rats. The COX-2 selective inhibitors celecoxib (105 micromol/kg) and rofecoxib (128 micromol/kg) however, were not effective in any of the groups studied. We conclude that inhibition of both COX isoenzymes is needed to achieve an effective analgesia in inflammation. PMID:11378164

Mazario, J; Gaitan, G; Herrero, J F

2001-06-01

306

Working data together: the accountability and reflexivity of digital astronomical practice.  

PubMed

Drawing on ethnomethodology, this article considers the sequential work of astronomers who combine observations from telescopes at two observatories in making a data set for scientific analyses. By witnessing the induction of a graduate student into this work, it aims at revealing the backgrounded assumptions that enter it. I find that these researchers achieved a consistent data set by engaging diverse evidential contexts as contexts of accountability. Employing graphs that visualize data in conventional representational formats of observational astronomy, experienced practitioners held each other accountable by using an 'implicit cosmology', a shared (but sometimes negotiable) characterization of 'what the universe looks like' through these formats. They oriented to data as malleable, that is, as containing artifacts of the observing situation which are unspecified initially but can be defined and subsequently removed. Alternating between reducing data and deducing astronomical phenomena, they ascribed artifacts to local observing conditions or computational procedures, thus maintaining previously stabilized phenomena reflexively. As researchers in data-intensive sciences are often removed from the instruments that generated the data they use, this example demonstrates how scientists can achieve agreement by engaging stable 'global' data sets and diverse contexts of accountability, allowing them to bypass troubling features and limitations of data generators. PMID:24941613

Hoeppe, Götz

2014-04-01

307

Dual adaptation and adaptive generalization of the human vestibulo-ocular reflex  

NASA Technical Reports Server (NTRS)

In two experiments, we examined the possibility that the human vestibulo-ocular reflex (VOR) is subject to dual adaptation (the ability to adapt to a sensory rearrangement more rapidly and/or more completely after repeated experience with it) and adaptive generalization (the ability to adapt more readily to a novel sensory rearrangement as a result of prior dual adaptation training). In Experiment 1, the subjects actively turned the head during alternating exposure to a visual-vestibular rearrangement (target/head gain = 0.5) and the normal situation (target/head gain = 0.0). These conditions produced both adaptation and dual adaptation of the VOR but no evidence of adaptive generalization when tested with a target/head gain of 1.0. Experiment 2, in which exposure to the 0.5 gain entailed externally controlled (i.e., passive) whole body rotation, resulted in VOR adaptation but no dual adaptation. As in Experiment 1, no evidence of adaptive generalization was found.

Welch, R. B.; Bridgeman, B.; Williams, J. A.; Semmler, R.

1998-01-01

308

Readaptation of the Vestibulo-Ocular Reflex Relieves the Mal De Debarquement Syndrome  

PubMed Central

The mal de debarquement syndrome (MdDS), a continuous feeling of swaying, rocking, and/or bobbing, generally follows travel on the sea. The associated symptoms cause considerable distress. The underlying neural mechanisms are unknown, and to date there have been no effective treatments for this condition. Results in monkeys and humans suggested that MdDS was caused by maladaptation of the vestibulo-ocular reflex (VOR) to roll of the head during rotation. We studied 24 subjects with persistent MdDS (3 males, 21 females; 19.1?±?33?months). Physical findings included body oscillation at 0.2?Hz, oscillating vertical nystagmus when the head was rolled from side-to-side in darkness, and unilateral rotation during the Fukuda stepping test. We posited that the maladapted rocking and the physical symptoms could be diminished or extinguished by readapting the VOR. Subjects were treated by rolling the head from side-to-side while watching a rotating full-field visual stimulus. Seventeen of the 24 subjects had a complete or substantial recovery on average for approximately 1?year. Six were initially better, but the symptoms recurred. One subject did not respond to treatment. Thus, readaptation of the VOR has led to a cure or substantial improvement in 70% of the subjects with MdDS. We conclude that the adaptive processes associated with roll-while-rotating are responsible for producing MdDS, and that the symptoms can be reduced or resolved by readapting the VOR. PMID:25076935

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

2014-01-01

309

The proboscis extension reflex to evaluate learning and memory in honeybees ( Apis mellifera): some caveats  

NASA Astrophysics Data System (ADS)

The proboscis extension reflex (PER) is widely used in a classical conditioning (Pavlovian) context to evaluate learning and memory of a variety of insect species. The literature is particularly prodigious for honeybees ( Apis mellifera) with more than a thousand publications. Imagination appears to be the only limit to the types of challenges to which researchers subject honeybees, including all the sensory modalities and a broad diversity of environmental treatments. Accordingly, some remarkable insights have been achieved using PER. However, there are several challenges to evaluating the PER literature that warrant a careful and thorough review. We assess here variation in methods that makes interpretation of studies, even those researching the same question, tenuous. We suggest that the numerous variables that might influence experimental outcomes from PER be thoroughly detailed by researchers. Moreover, the influence of individual variables on results needs to carefully evaluated, as well as among two or more variables. Our intent is to encourage investigation of the influence of numerous variables on PER results.

Frost, Elisabeth H.; Shutler, Dave; Hillier, Neil Kirk

2012-09-01

310

Artificial Balance: Restoration of the Vestibulo-Ocular Reflex in Humans with a Prototype Vestibular Neuroprosthesis  

PubMed Central

The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently, there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the vestibulo-ocular reflex (VOR), the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss. PMID:24808890

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

2014-01-01

311

Encoding of the cough reflex in anesthetized guinea pigs  

PubMed Central

We have previously described the physiological and morphological properties of the cough receptors and their sites of termination in the airways and centrally in the nucleus tractus solitarius (nTS). In the present study, we have addressed the hypothesis that the primary central synapses of the cough receptors subserve an essential role in the encoding of cough. We found that cough requires sustained, high-frequency (?8-Hz) afferent nerve activation. We also found evidence for processes that both facilitate (summation, sensitization) and inhibit the initiation of cough. Sensitization of cough occurs with repetitive subthreshold activation of the cough receptors or by coincident activation of C-fibers and/or nTS neurokinin receptor activation. Desensitization of cough evoked by repetitive and/or continuous afferent nerve activation has a rapid onset (<60 s) and does not differentiate between tussive stimuli, suggesting a central nervous system-dependent process. The cough reflex can also be actively inhibited upon activation of other airway afferent nerve subtypes, including slowly adapting receptors and pulmonary C-fibers. The sensitization and desensitization of cough are likely attributable to the prominent, primary, and unique role of N-methyl-d-aspartate receptor-dependent signaling at the central synapses of the cough receptors. These attributes may have direct relevance to the presentation of cough in disease and for the effectiveness of antitussive therapies. PMID:20926760

Mori, Nanako

2011-01-01

312

Reflexive obstacle avoidance for kinematically-redundant manipulators  

NASA Technical Reports Server (NTRS)

Dexterous telerobots incorporating 17 or more degrees of freedom operating under coordinated, sensor-driven computer control will play important roles in future space operations. They will also be used on Earth in assignments like fire fighting, construction and battlefield support. A real time, reflexive obstacle avoidance system, seen as a functional requirement for such massively redundant manipulators, was developed using arm-mounted proximity sensors to control manipulator pose. The project involved a review and analysis of alternative proximity sensor technologies for space applications, the development of a general-purpose algorithm for synthesizing sensor inputs, and the implementation of a prototypical system for demonstration and testing. A 7 degree of freedom Robotics Research K-2107HR manipulator was outfitted with ultrasonic proximity sensors as a testbed, and Robotics Research's standard redundant motion control algorithm was modified such that an object detected by sensor arrays located at the elbow effectively applies a force to the manipulator elbow, normal to the axis. The arm is repelled by objects detected by the sensors, causing the robot to steer around objects in the workspace automatically while continuing to move its tool along the commanded path without interruption. The mathematical approach formulated for synthesizing sensor inputs can be employed for redundant robots of any kinematic configuration.

Karlen, James P.; Thompson, Jack M., Jr.; Farrell, James D.; Vold, Havard I.

1989-01-01

313

Primate translational vestibuloocular reflexes. IV. Changes after unilateral labyrinthectomy  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

314

Methods of assessing vagus nerve activity and reflexes  

PubMed Central

The methods used to assess cardiac parasympathetic (cardiovagal) activity and its effects on the heart in both humans and animal models are reviewed. Heart rate (HR)-based methods include measurements of the HR response to blockade of muscarinic cholinergic receptors (parasympathetic tone), beat-to-beat HR variability (HRV) (parasympathetic modulation), rate of post-exercise HR recovery (parasympathetic reactivation), and reflex-mediated changes in HR evoked by activation or inhibition of sensory (afferent) nerves. Sources of excitatory afferent input that increase cardiovagal activity and decrease HR include baroreceptors, chemoreceptors, trigeminal receptors, and subsets of cardiopulmonary receptors with vagal afferents. Sources of inhibitory afferent input include pulmonary stretch receptors with vagal afferents and subsets of visceral and somatic receptors with spinal afferents. The different methods used to assess cardiovagal control of the heart engage different mechanisms, and therefore provide unique and complementary insights into underlying physiology and pathophysiology. In addition, techniques for direct recording of cardiovagal nerve activity in animals; the use of decerebrate and in vitro preparations that avoid confounding effects of anesthesia; cardiovagal control of cardiac conduction, contractility, and refractoriness; and noncholinergic mechanisms are described. Advantages and limitations of the various methods are addressed, and future directions are proposed. PMID:20577901

Chapleau, Mark W.; Sabharwal, Rasna

2015-01-01

315

[Reflex sympathetic dystrophy: still a poorly defined entity].  

PubMed

The reflex sympathetic dystrophy (algodystrophy) constitutes a large nosological field of which the main characteristics are the appearance of algic and vasomotor symptoms at a segmental level of a limb, in consequence to diverse pathologies (trauma, cardiovascular disease, etc.). The widely accepted theory of a dysregulation of the sympathetic nervous system is nowadays counter-balanced by recent work highlighting the preponderant role of polymodal afferent nerves in the pathophysiology of this disease. The diagnosis, being above-all clinical, is marked by two distinct phases appearing in a variable chronology; a warm phase associating fluctionating pain, stiffness and vasomotor symptoms, and then a cold phase characterized by fibrosis, leading to disabling trophic symptoms. Spontaneous recovery is usual and can be delayed by up to two years, however irreversible sequelae can occur. Paraclinical investigations are necessary to confirm the diagnosis: absence of a biological inflammatory syndrome, early hyperfixation on bone scintography or an abnormality in the MRI signal in the sub-chondral zones. The X-ray shows late local demineralization that is often non-homogenous. The treatment is poorly codified. First-line treatment in France, other than antalgics, often rests on the calcitonins. Intravenous diphosphonates are proposed by some in case of treatment failure. Regional venous blocks are sometimes performed in resistant and disabling forms. Rehabilitation and psychological support have a primordial place throughout the evolution of the illness. PMID:15086053

Ornetti, Paul; Maillefert, Jean-Francis

2004-01-31

316

Quantification of the stapedial reflex reveals delayed responses in autism.  

PubMed

Autism is a developmental disorder characterized, in part, by sensory abnormalities. It is well established that most if not all patients with autism have problems with auditory processing, ranging from deafness to hyperacusis, and physiological testing of auditory function (i.e. auditory brain stem responses) implicates brain stem dysfunction in autism. Additionally, previous research from this lab has revealed significantly fewer auditory brain stem neurons in autistic subjects as young as 2 years of age. These observations have led us to hypothesize that objective, noninvasive measures of auditory function can be used as an early screening tool to identify neonates with an elevated risk of carrying a diagnosis of autism. Here, we provide a detailed quantitative investigation of the acoustic stapedial reflex (ASR), a three- or four-neuron brain stem circuit, in young autistic subjects and normal developing controls. Indeed, we find significantly lower thresholds, responses occurring at significantly longer latency and right-left asymmetry in autistic subjects. The results from this investigation support deficits in auditory function as a cardinal feature of autism and suggest that individuals with autism can be identified by their ASR responses. PMID:23825093

Lukose, Richard; Brown, Kevin; Barber, Carol M; Kulesza, Randy Joseph

2013-10-01

317

Research of light reflex surface defects detection technology  

NASA Astrophysics Data System (ADS)

The surface defects (indentations, humps, scores) of semiconductor wafers are the major factor to affect the performance of the semiconductor devices. Moreover, these defects make the manufacturing process difficult or yield of the semiconductor devices decrease. Consequently, it is necessary to do an on-line wafers detection in the benefit of the performance and yield of the devices. Thus, developing a way suited for practical detection is the urgent affair faced to people. The optical methods are the most suited ways for surface defects detection because of their non-contact operation. We discuss a relatively unknown method of the light reflex surface defects detection technology (Makyoh (or magic-mirror) topography (MT)). The optical system that we designed achieves the detection mode of the parallel light vertical incidence for the first time. It corrects the deviation between the tradition light path and arithmetic, promotes the detection precision. A lot of experiments based on this optical system are taken to get the difference between the detection modes of vertical incidence and the oblique incidence. The experiments prove that the vertical incidence mode excels the oblique incidence mode. The MT images are also analyzed and disposed. The quantitative measurement can be realized by digital image processing technology.

Tian, Jiajun; Yao, Yong; Sun, Yunxu; Shi, Weijie; Zhao, Xinhui; Yu, Xuelian

2008-03-01

318

Evolution of Gustatory Reflex Systems in the Brainstems of Fishes  

PubMed Central

The great number of species of teleosts permits highly specialized forms to evolve to occupy particular niches. This diversity allows for extreme variations in brain structure according to particular sensory or motor adaptations. In the case of the taste system, goldfish (Carassius auratus) and some carps have evolved a specialized intraoral food-sorting apparatus along with corresponding specializations of gustatory centers in the brainstem. A comparison of circuitry within the complex vagal lobe of goldfish, and the of simpler gustatory lobes in catfish (Ictalurus punctatus) shows numerous similarities in organization and neurotransmitters. Double labeling studies using horseradish peroxidase (HRP) and biotinylated dextran amine in catfish shows a direct projection from the vagal lobe to the motoneurons of nuc. ambiguus which innervate oropharyngeal musculature. Thus a 3-neuron reflex arc connects gustatory input to motor output. In the vagal lobe of goldfish, a similar 3-neuron arc can be identified: from primary gustatory afferent, to vagal lobe interneuron, thence to dendrites of the vagal motoneurons that innervate the pharyngeal muscles. Thus despite large differences in the gross appearance of the vagal gustatory systems in the brains of catfish and goldfish, the essential connectivity and circuitry is similar. This suggests that evolutionary change in the central nervous system largely proceeds by rearrangement and elaboration of existing systems, rather than by addition of new structures or circuits. PMID:20160963

Finger, Thomas E.

2009-01-01

319

Reflex Control of Robotic Gait Using Human Walking Data  

PubMed Central

Control of human walking is not thoroughly understood, which has implications in developing suitable strategies for the retraining of a functional gait following neurological injuries such as spinal cord injury (SCI). Bipedal robots allow us to investigate simple elements of the complex nervous system to quantify their contribution to motor control. RunBot is a bipedal robot which operates through reflexes without using central pattern generators or trajectory planning algorithms. Ground contact information from the feet is used to activate motors in the legs, generating a gait cycle visually similar to that of humans. Rather than developing a more complicated biologically realistic neural system to control the robot's stepping, we have instead further simplified our model by measuring the correlation between heel contact and leg muscle activity (EMG) in human subjects during walking and from this data created filter functions transferring the sensory data into motor actions. Adaptive filtering was used to identify the unknown transfer functions which translate the contact information into muscle activation signals. Our results show a causal relationship between ground contact information from the heel and EMG, which allows us to create a minimal, linear, analogue control system for controlling walking. The derived transfer functions were applied to RunBot II as a proof of concept. The gait cycle produced was stable and controlled, which is a positive indication that the transfer functions have potential for use in the control of assistive devices for the retraining of an efficient and effective gait with potential applications in SCI rehabilitation. PMID:25347544

Macleod, Catherine A.; Meng, Lin; Conway, Bernard A.; Porr, Bernd

2014-01-01

320

Intrasession and intersession reliability of the soleus H-reflex in supine and standing positions.  

PubMed

The Hoffmann reflex (H-reflex) is a measure of motoneuron pool excitability, which is valuable in determining muscle inhibition caused by joint damage (arthrogenic muscle inhibition). In order to detect changes in H-reflex due to injury, the reliability of such a measurement must be established. The purpose of this study was to establish the intrasession and intersession reliability of soleus H-reflex in a supine and standing position. Thirteen healthy volunteers (age 10 +/- 2.63 yr, height 171.35 +/- 10.19 cm, mass 69.62 +/- 13.03 Kg) with no lower extremity orthopedic or neurological disorders within the past year participated in this study. To determine the intrasession and intersession reliability of this measure in a supine resting position and a one-leg standing position, EMG data were collected from the soleus while the tibial nerve was stimulated in the popliteal space. A high voltage (120-200 V), short duration (1.0 msec) stimulus was automatically triggered, eliciting a reflex twitch detected by surface EMG. Several of these measurements were performed with 20 second rest intervals to find the maximum H-reflex. The maximum H-reflex was located by adjusting the intensity of the stimulus. Once a maximum H-reflex was found, 12 measurements were taken in that position with 20 second rest intervals. These steps were repeated for each position (supine and standing) at the same time for 5 consecutive days. Intrasession reliability was computed using 12 measurement trials (12), 12 measurement trials dropping the high and low score (12x), the first 7 measurement trials dropping the high and low score (7x), and the first 5 measurement trials (5). Intrasession and intersession reliability over five consecutive days was estimated using intraclass correlation coefficients (ICC (3, 1)). The supine intrasession reliability measurements were as follows: 0.932 (12), 0.932 (12x), 0.935 (7x), and 0.932 (5). The standing intrasession reliability was 0.853 (12), 0.852 (12x), 0.865 (7x), and 0.862 (5). The intersession reliability was 0.938 in the supine position and 0.803 in the standing position. These results indicate that the H-reflex measured using our protocol in a supine and standing position is a reliable assessment within sessions and between sessions. Five measurements are sufficient to observe reliable measurements within a single session. Most importantly, this data shows that the H-reflex is a reliable assessment that may be used to measure small changes in motoneuron pool excitability over time. PMID:10746184

Hopkins, J T; Ingersoll, C D; Cordova, M L; Edwards, J E

2000-03-01

321

Variability of motoneuron activation and the modulation of force production in a postural reflex of the hermit crab abdomen  

Microsoft Academic Search

The tri-phasic reflex in hermit crab (Pagurus pollicarus) abdomen is triggered by local mechanoreceptors and is essential for postural control. The reflex consists of three stereotypical phases: a brief, high-frequency burst, a transient cessation of firing, and a late-discharge that is much lower in frequency than the initial burst. To better understand the reflex generation of force, variability of motoneuron

Jacob L. Krans; William D. Chapple

2005-01-01

322

Modulation of the blink reflex and P3 component of the startle response during an interoceptive challenge.  

PubMed

The blink reflex component of the startle response is potentiated during processing of exteroceptive unpleasant stimuli. In contrast, blink magnitudes are often inhibited during interoceptive challenges. We measured respiration, blink magnitudes, and the P3 component to the acoustic startle probes in 34 participants while breathing against a mild resistance (mask-with-tubing) compared to breathing with no mask. Breathing through a mask with tubing resulted in increased inspiratory resistance as indicated by increased flow rate and tidal volume, a compensatory breathing pattern. Blink magnitudes to probes presented during the mask-with-tubing condition were inhibited compared to no-mask. Likewise, the probe P3 component was smaller during breathing through a mild resistance. These data suggest that startle inhibition during interoceptive challenges might be due to a shift in attention towards the mildly unpleasant interoceptive stimuli. PMID:25059805

Alius, Manuela G; Pané-Farré, Christiane A; Löw, Andreas; Hamm, Alfons O

2015-01-01

323

Pulmonary oedema produced by scorpion venom augments a phenyldiguanide-induced reflex response in anaesthetized rats.  

PubMed

1. The involvement of pulmonary oedema produced by scorpion venom in augmenting a phenyldiguanide (PDG)-induced reflex response was evaluated in urethane-anaesthetized rats. 2. PDG-induced bradycardiac, hypotensive and apnoeic responses, expressed as time-response area, exhibited similarities before or after venom treatment. Hence, the time-response area of bradycardia was taken as a reflex parameter. Pulmonary oedema was determined by physical evaporation and histological methods. 3. Exposure to Indian red scorpion (Buthus tamulus, BT; i.v.) venom for 30 min increased the pulmonary water content (P < 0.05; Student's t test) and augmented the PDG-induced bradycardiac reflex response by more than 2 times (P < 0.001). The increase of pulmonary water content was maximal with 100 microg kg-1 of venom and the augmentation was maximal with 10 microg kg-1. In a separate series of experiments, the venom (100 microg kg-1)-induced pulmonary oedema was confirmed by histological and physical methods. In this group also, the venom augmented the reflex to the same magnitude. 4. Pulmonary oedema (physical and histological) and augmentation of the bradycardiac reflex response after BT venom (100 microg kg-1; i.v.) were absent in animals pretreated with aprotinin, a kallikrein-kinin inhibitor (6000 KIU; i. v.). 5. Ondansetron (10 microg kg-1; i.v.), a 5-HT3 receptor antagonist, failed to block the venom-induced pulmonary oedema (physical and histological) but blocked the venom-induced augmentation of the reflex. 6. The results of this study indicate that the venom-induced augmentation of the PDG reflex is associated with pulmonary oedema involving kinins utilizing 5-HT3 receptors. PMID:10581322

Deshpande, S B; Bagchi, S; Rai, O P; Aryya, N C

1999-12-01

324

Propranolol, but not naloxone, enhances spinal reflex bladder activity and reduces pudendal inhibition in cats.  

PubMed

This study examined the role of ?-adrenergic and opioid receptors in spinal reflex bladder activity and in the inhibition induced by pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS). Spinal reflex bladder contractions were induced by intravesical infusion of 0.25% acetic acid in ?-chloralose-anesthetized cats after an acute spinal cord transection (SCT) at the thoracic T9/T10 level. PNS or TNS at 5 Hz was applied to inhibit these spinal reflex contractions at 2 and 4 times the threshold intensity (T) for inducing anal or toe twitch, respectively. During a cystrometrogram (CMG), PNS at 2T and 4T significantly (P < 0.05) increased bladder capacity from 58.0 ± 4.7% to 85.8 ± 10.3% and 96.5 ± 10.7%, respectively, of saline control capacity, while TNS failed to inhibit spinal reflex bladder contractions. After administering propranolol (3 mg/kg iv, a ?1/?2-adrenergic receptor antagonist), the effects of 2T and 4T PNS on bladder capacity were significantly (P < 0.05) reduced to 64.5 ± 9.5% and 64.7 ± 7.3%, respectively, of the saline control capacity. However, the residual PNS inhibition (about 10% increase in capacity) was still statistically significant (P < 0.05). Propranolol treatment also significantly (P = 0.0019) increased the amplitude of bladder contractions but did not change the control bladder capacity. Naloxone (1 mg/kg iv, an opioid receptor antagonist) had no effect on either spinal reflex bladder contractions or PNS inhibition. At the end of experiments, hexamethonium (10 mg/kg iv, a ganglionic blocker) significantly (P < 0.05) reduced the amplitude of the reflex bladder contractions. This study indicates an important role of ?1/?2-adrenergic receptors in pudendal inhibition and spinal reflex bladder activity. PMID:25394827

Rogers, Marc J; Xiao, Zhiying; Shen, Bing; Wang, Jicheng; Schwen, Zeyad; Roppolo, James R; de Groat, William C; Tai, Changfeng

2015-01-01

325

The sacral parasympathetic reflex pathway regulating colonic motility and defaecation in the cat.  

PubMed Central

1. The sacral parasympathetic outflow to the large intestine of the cat was studied by monitoring simultaneously intestinal motility and the efferent firing in postganglionic fibres on the serosal surface of the mid-distal colon. 2. Increases in efferent firing were noted during the occurrence of spontaneous propulsive activity (tonic pressure waves) or segmental contractions (slow rhythmic pressure waves). The neural discharge was not altered by transection of the lumbar sympathetic innervation to the colon but was blocked by interruption of the sacral parasympathetic outflow. 3. Electrical stimulation of pelvic nerve afferents arising in the colon or distension of the colon or rectum evoked reflex increases in efferent firing and sustained propulsive contractions that were associated with defaecation. Both responses were abolished by transection of the pelvic nerves or sacral dorsal roots. 4. Electrical stimulation of colonic afferent fibres also evoked synchronous reflex discharges in colonic efferents at latencies ranging from 180 to 300 msec. The discharges were enhanced during propulsive contractions, abolished by transection of the pelvic nerves but not altered by transection of the lumbar sympathetic nerves. 5. Sacral reflexes were present in cats with intact spinal cord and in chronic spinal animals (transection at T10-T12). The reflexes recovered within minutes to several hours after acute transection of the spinal cord. 6. Electrophysiological measurements indicated that the sacral reflexes to the large intestine were mediated by non-myelinated afferent and preganglionic efferent fibres. The central delay for the reflex was estimated to be 45-60 msec. 7. It is concluded that the sacral parasympathetic reflexes to the large intestine are mediated via a spinal pathway and have an essential role in the initiation of propulsive activity during defaecation. PMID:650474

De Groat, W C; Krier, J

1978-01-01

326

Alimentary conditioned reflexes in dogs on activation and blockage of the cholinoreactive amygdaloid system  

Microsoft Academic Search

Conclusions 1.Chemical stimulation of the basolateral area of the amygdala by acetylcholine at a dose of 300 µg, carbocholine at a dose of 0.5 µg, and atropine at a dose of 60 µg changes the production of the secretory component of alimentary reactions but has no effect on the production of the instrumental component.2.Activation of the cholinoreactive system of the

S. I. Shefer

1989-01-01

327

Trigeminocardiac reflex in neurosurgical practice: An observational prospective study  

PubMed Central

Background: Considering wide variations regarding the incidence of trigeminocardiac reflex (TCR) during cranial neurosurgical procedures, and paucity of reliable data, we intended to design a prospective study to determine the incidence of TCR in patients undergoing standard general anesthesia for surgery of supra/infra-tentorial cranial and skull base lesions. Methods: A total of 190 consecutive patients candidate for elective surgery of supra-tentorial, infra-tentorial, and skull base lesions were enrolled. All the patients were operated in the neurosurgical operating room of a university-affiliated teaching hospital. All surgeries were performed using sufficient depth of anesthesia achieved by titration of propofol–alfentanil mixture, adjusted according to target Cerebral State Index (CSI) values (40-60). All episodes of bradycardia and hypotension indicating the occurrence of TCR during the surgery (sudden decrease of more than 20% from the previous level) were recorded. Results: Four patients, two female and two male, developed episodes of TCR during surgery (4/190; 2.1%). Three patients showed one episode of TCR just at the end of operation when the skin sutures were applied while CSI values were 70-77 and in the last case, when small tumor samples were taken from just beneath the lateral wall of the cavernous sinus TCR episode was seen while the CSI value was 51. Conclusion: TCR is a rare phenomenon during brain surgeries when patient is anesthetized using standard techniques. Keeping the adequate depth of anesthesia using CSI monitoring method may be an advisable strategy during whole period of a neurosurgical procedure. PMID:24083052

Etezadi, Farhad; Orandi, Amir Ali; Orandi, Amir Hosein; Najafi, Atabak; Amirjamshidi, Abbas; Pourfakhr, Pejman; Khajavi, Mohammad Reza; Abbassioun, Kazem

2013-01-01

328

Relationship of noradrenergic locus coeruleus neurones to vestibulospinal reflexes.  

PubMed

The electrical activity of presumably noradrenergic locus coeruleus (LC) neurones was recorded in decerebrate cats during roll tilt of the animal at 0.15 Hz, +/- 10 degrees, leading to sinusoidal labyrinth stimulation. Among the tested units, some of which projected to the lumbosacral spinal cord, 56.7% responded to animal tilt. Most of these neurones were activated during side-up and depressed during side-down tilt of the animal, while a smaller proportion of units showed the opposite response pattern. This predominant response pattern of LC neurones and coeruleospinal (CS) neurones to animal tilt was opposite in activation polarity to that of vestibulospinal (VS) neurones projecting to the same segments of the spinal cord. Both the VS and the CS neurones exert a direct excitatory influence on ipsilateral limb extensor motoneurones. However, VS neurones excite corresponding Renshaw (R) cells, though due to activation of limb extensor motoneurones and their recurrent collaterals, the CS neurones may inhibit them. It appears, therefore, that during side-down animal tilt, the motoneurones innervating the ipsilateral limb extensors are excited by the increased discharge of VS neurones, while the corresponding R-cells are disinhibited due to the reduced discharge of CS neurones. The functional coupling between ipsilateral limb extensor motoneurones and the corresponding R-cells would then increase, just at the time in which these motoneurones are driven by the excitatory VS volleys, thus limiting the response gain of limb extensors to labyrinth stimulation. This hypothesis is supported by two facts: (1) R-cells linked with limb extensor motoneurones discharge during side-down tilt, thus firing in phase with the excitatory VS volleys, and (2) functional inactivation of the noradrenergic LC neurones increases the gain of the vestibulospinal reflexes acting on limb extensors. PMID:2699372

Pompeiano, O

1989-01-01

329

Neural learning rules for the vestibulo-ocular reflex  

NASA Technical Reports Server (NTRS)

Mechanisms for the induction of motor learning in the vestibulo-ocular reflex (VOR) were evaluated by recording the patterns of neural activity elicited in the cerebellum by a range of stimuli that induce learning. Patterns of climbing-fiber, vestibular, and Purkinje cell simple-spike signals were examined during sinusoidal head movement paired with visual image movement at stimulus frequencies from 0.5 to 10 Hz. A comparison of simple-spike and vestibular signals contained the information required to guide learning only at low stimulus frequencies, and a comparison of climbing-fiber and simple-spike signals contained the information required to guide learning only at high stimulus frequencies. Learning could be guided by comparison of climbing-fiber and vestibular signals at all stimulus frequencies tested, but only if climbing fiber responses were compared with the vestibular signals present 100 msec earlier. Computational analysis demonstrated that this conclusion is valid even if there is a broad range of vestibular signals at the site of plasticity. Simulations also indicated that the comparison of vestibular and climbing-fiber signals across the 100 msec delay must be implemented by a subcellular "eligibility" trace rather than by neural circuits that delay the vestibular inputs to the site of plasticity. The results suggest two alternative accounts of learning in the VOR. Either there are multiple mechanisms of learning that use different combinations of neural signals to drive plasticity, or there is a single mechanism tuned to climbing-fiber activity that follows activity in vestibular pathways by approximately 100 msec.

Raymond, J. L.; Lisberger, S. G.

1998-01-01

330

Role of adenosine A{sub 2A} receptor signaling in the nicotine-evoked attenuation of reflex cardiac sympathetic control  

SciTech Connect

Baroreflex dysfunction contributes to increased cardiovascular risk in cigarette smokers. Given the importance of adenosinergic pathways in baroreflex control, the hypothesis was tested that defective central adenosinergic modulation of cardiac autonomic activity mediates the nicotine-baroreflex interaction. Baroreflex curves relating changes in heart rate (HR) to increases or decreases in blood pressure (BP) evoked by i.v. doses (1-16 {mu}g/kg) of phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious rats; slopes of the curves were taken as measures of baroreflex sensitivity (BRS). Nicotine (25 and 100 {mu}g/kg i.v.) dose-dependently reduced BRS{sub SNP} in contrast to no effect on BRS{sub PE}. BRS{sub SNP} was also attenuated after intracisternal (i.c.) administration of nicotine. Similar reductions in BRS{sub SNP} were observed in rats pretreated with atropine or propranolol. The combined treatment with nicotine and atropine produced additive inhibitory effects on BRS, an effect that was not demonstrated upon concurrent exposure to nicotine and propranolol. BRS{sub SNP} was reduced in preparations treated with i.c. 8-phenyltheophylline (8-PT, nonselective adenosine receptor antagonist), 8-(3-Chlorostyryl) caffeine (CSC, A{sub 2A} antagonist), or VUF5574 (A{sub 3} antagonist). In contrast, BRS{sub SNP} was preserved after blockade of A{sub 1} (DPCPX) or A{sub 2B} (alloxazine) receptors or inhibition of adenosine uptake by dipyridamole. CSC or 8-PT abrogated the BRS{sub SNP} depressant effect of nicotine whereas other adenosinergic antagonists were without effect. Together, nicotine preferentially impairs reflex tachycardia via disruption of adenosine A{sub 2A} receptor-mediated facilitation of reflex cardiac sympathoexcitation. Clinically, the attenuation by nicotine of compensatory sympathoexcitation may be detrimental in conditions such as hypothalamic defense response, posture changes, and ventricular rhythms. - Research Highlights: > The role of central adenosinergic sites in the nicotine-baroreflex interaction was investigated. > Inhibition of reflex sympathoinhibition mediates the BRS depressant action of nicotine. > Nicotine preferentially impairs reflex tachycardia via disruption of adenosine A{sub 2A} signaling. > The attenuation by nicotine of reflex sympathetic activity is clinically important.

El-Mas, Mahmoud M., E-mail: mahelm@hotmail.com; El-gowilly, Sahar M.; Fouda, Mohamed A.; Saad, Evan I.

2011-08-01

331

Role of medullary GABA signal transduction on parasympathetic reflex vasodilatation in the lower lip.  

PubMed

In the orofacial area, noxious stimulation of the orofacial structure in the trigeminal region evokes parasympathetic reflex vasodilatation, which occurs via the trigeminal spinal nucleus (Vsp) and the inferior/superior salivatory nucleus (ISN/SSN). However, the neurotransmitter involved in the inhibitory synaptic inputs within these nuclei has never been described. This parasympathetic reflex vasodilatation is suppressed by GABAergic action of volatile anesthetics, such as isoflurane, sevoflurane, and halothane, suggesting that medullary GABAergic mechanism exerts its inhibitory effect on the parasympathetic reflex via an activation of GABA receptors. The aim of the present study was to determine the role of GABA(A) and GABA(B) receptors in the Vsp and the ISN in regulating the lingual nerve (LN)-evoked parasympathetic reflex vasodilatation in the lower lip. Under urethane anesthesia (1g/kg), change in lower lip blood flow elicited by electrical stimulation of the LN was recorded in cervically vago-sympathectomized rats. Microinjection of GABA (10 ?M; 0.3 ?l/site) into the Vsp or the ISN significantly and reversibly attenuated the LN-evoked parasympathetic reflex vasodilatation. Microinjection of the GABA(A) receptor-selective agonist muscimol (100 ?M; 0.3 ?l/site) or the GABA(B) receptor-selective agonist baclofen (100 ?M; 0.3 ?l/site) into the Vsp or the ISN significantly and irreversibly reduced this reflex vasodilatation, and these effects were attenuated by pretreatment with microinjection of each receptor-selective antagonists [GABA(A) receptor selective antagonist bicuculline methiodide (1mM; 0.3 ?l/site) or GABA(B) receptor selective antagonist CGP-35348 (1mM; 0.3 ?l/site)] into the Vsp or the ISN. Microinjection of these antagonists alone into the Vsp or the ISN had no significant effect on this reflex vasodilatation. In addition, microinjection (0.3 ?l/site) of the mixture of muscimol (100 ?M) and baclofen (100 ?M) into the Vsp or the ISN also significantly reduced this reflex vasodilatation. These results suggest that medullary GABA signal transduction inhibits the parasympathetic reflex vasodilatation in the rat lower lip via GABA(A) and GABA(B) receptors in the Vsp and the ISN. PMID:22226507

Kawakami, So; Izumi, Hiroshi; Masaki, Eiji; Kuchiiwa, Satoshi; Mizuta, Kentaro

2012-02-01

332

The long-latency reflex is composed of at least two functionally independent processes.  

PubMed

The nervous system counters mechanical perturbations applied to the arm with a stereotypical sequence of muscle activity, starting with the short-latency stretch reflex and ending with a voluntary response. Occurring between these two events is the enigmatic long-latency reflex. Although researchers have been fascinated by the long-latency reflex for over 60 years, some of the most basic questions about this response remain unresolved and often debated. In the present study we help resolve one such question by providing clear evidence that the human long-latency reflex during a naturalistic motor task is not a single functional response; rather, it appears to reflect the output of (at least) two functionally independent processes that overlap in time and sum linearly. One of these functional components shares an important attribute of the short-latency reflex (i.e., automatic gain scaling, sensitivity to background load), and the other shares a defining feature of voluntary control (i.e., task dependency, sensitivity to goal target position). We further show that the task-dependent component of long-latency activity reflects a feedback control process rather than the simplest triggered reaction to a mechanical stimulus. PMID:21543751

Pruszynski, J Andrew; Kurtzer, Isaac; Scott, Stephen H

2011-07-01

333

Stretch reflex improves rolling stability during hopping of a decerebrate biped system.  

PubMed

When humans hop, attitude recovery can be observed in both the sagittal and frontal planes. While it is agreed that the brain plays an important role in leg placement, the role of low-level feedback (the stretch reflex) on frontal plane stabilization remains unclear. Seeking to better understand the contribution of the soleus stretch reflex to rolling stability, we performed experiments on a biomimetic humanoid hopping robot. Various reflex responses to touching the floor, ranging from no response to long muscle activations, were examined, and the effect of a delay upon touching the floor was also examined. We found that the stretch reflex brought the system closer to stable, straight hopping. The presence of a delay did not affect the results; both the cases with and without a delay outperformed the case without a reflex response. The results of this study highlight the importance of low-level control in locomotion for which body stabilization does not require higher-level signals. PMID:25599138

Rosendo, Andre; Liu, Xiangxiao; Shimizu, Masahiro; Hosoda, Koh

2015-01-01

334

Nurses' decision on seclusion: patient characteristics, contextual factors and reflexivity in teams.  

PubMed

While many characteristics of patients, professionals and facilities with relevance to seclusion rates have been investigated, their relative importance is unclear. Virtually no attention has been paid to team processes and reflexivity in relation to decision making on seclusion. The aim of this paper is to estimate the effects of these factors on nurse decision making on seclusion. Sixty Dutch psychiatric nurses of four closed wards reported team reflexivity and their tendency to seclude a theoretical patient. Approachability (whether there was a good or hardly any possibility to communicate with the patient), staffing level and confidence within the team had the greatest impact on the decision to seclude. Intra class correlation was 0.30. There was a large interaction effect of reflexivity with team 4, and team reflexivity was highly correlated with team tendency to avoid seclusion. In nurses' decision on seclusion, the effects of 'pure' patient characteristics are small as compared with the effects of interpersonal and contextual factors, and nurses vary widely in their judgement. Team reflexivity is related to the tendency to prevent seclusion. PMID:22074324

Boumans, C E; Egger, J I M; Souren, P M; Mann-Poll, P S; Hutschemaekers, G J M

2012-04-01

335

Some conceptual remarks about supraspinal mechanisms in the control of voluntary and reflex motor activities.  

PubMed

The present paper analyses the supraspinal control of motor functions and sensorimotor integrations. Attention was paid mainly to three phenomena involved in these mechanisms: the Bereitschaftspotential, the long latency reflex responses and the short latency somatosensory evoked potentials (SEPs). The study includes the problems of long loop motor control and dyscontrol, the gating process of SEPs by movement, the role of N18 component of SEP and the analysis of supraspinal modulation of the H-reflex excitability curve in healthy subjects and in patients with some cerebral dysfunction. It was found that the amplitude of the Bereitschaftspotential increased with peripheral nerve stimulation. The experiments have shown a positive relationship between the long latency reflex latencies and the distance of the corresponding muscle from the brain. The amplitude of the long latency reflex response was found to be higher and its synchronization better in phasic movements than in a slightly sustained contraction. The short latency somatosensory evoked potentials were distinctly attenuated by movement gating. By its wide spread negativity, the N18 component probably facilitates the cortical transfer of the long latency muscle response. The H-reflex excitability curves in patients with various cerebral dysfunction exhibited a characteristic course corresponding approximately to the degree of dysfunction in focal cerebral lesions, arterial hypertension and neurasthenias. PMID:1446586

Jergelová, M; Podivinský, F

1992-01-01

336

Walking phase modulates H-reflex amplitude in flexor carpi radialis.  

PubMed

It is well established that remote whole-limb rhythmic movement (e.g., cycling or stepping) induces suppression of the Hoffman (H-) reflex evoked in stationary limbs. However, the dependence of reflex amplitude on the phase of the movement cycle (i.e., phase-dependence) has not been consistent across this previous research. The authors investigated the phase-dependence of flexor carpi radialis (FCR) H-reflex amplitudes during active walking and in kinematically matched static postures across the gait cycle. FCR H-reflexes were elicited in the stationary forearm with electrical stimulation to the median nerve. Significant phase-dependent modulation occurred during walking when the gait cycle was examined with adequate phase resolution. The suppression was greatest during midstance and midswing, suggesting increased ascending communication during these phases. There was no phase-dependent modulation in static standing postures and no correlation between lower limb background electromyography levels and H-reflex amplitude during active walking. This evidence, along with previous research demonstrating no phase modulation during passive walking, suggests that afferent feedback associated with joint position and leg muscle activation levels are not the sole source of the phase modulation seen during active walking. Possible sources of phase modulation include combinations of afferent feedback related to active movement or central motor commands or both. PMID:24313749

Domingo, Antoinette; Klimstra, Marc; Nakajima, Tsuyoshi; Lam, Tania; Hundza, Sandra R

2014-01-01

337

Endothelial nitric oxide synthase mediates the nitric oxide component of reflex cutaneous vasodilatation during dynamic exercise in humans.  

PubMed

Recent data suggests neuronal nitric oxide synthase (nNOS) mediates the NO component of reflex cutaneous vasodilatation with passive heat stress. We tested the hypothesis that nNOS inhibition would attenuate reflex cutaneous vasodilatation during sustained dynamic exercise in young healthy humans. All subjects first performed an incremental V?O2, peak test to exhaustion on a custom-built supine cycle ergometer. On a separate day, subjects were instrumented with four intradermal microdialysis fibres on the forearm and each randomly assigned as: (1) lactated Ringer's (control); (2) 20 mm N?-nitro-l-arginine methyl ester hydrochloride (non-selective NOS inhibitor); (3) 5 mm N-propyl-l-arginine (nNOS inhibitor); and (4) 10 mm N(5)-(1-iminoethyl)-l-ornithine dihydrochloride [endothelial NOS (eNOS) inhibitor]. Following microdialysis placement, subjects performed supine cycling with the experimental arm at heart level at 60% V?O2, peak for a period sufficient to raise core temperature 0.8°C. At the end of cycling, all microdialysis sites were locally heated to 43°C and sodium nitroprusside was perfused to elicit maximal vasodilatation. Mean arterial pressure, skin blood flow via laser-Doppler flowmetry and core temperature via ingestible telemetric pill were measured continuously; cutaneous vascular conductance (CVC) was calculated as laser-Doppler flowmetry/mean arterial pressure and normalized to maximum. There was no significant difference between control (58 ± 2%CVCmax) and nNOS-inhibited (56 ± 3%CVCmax) sites in response to exercise-induced hyperthermia. The increase in CVC at eNOS-inhibited (41 ± 3%CVCmax) and non-selective NOS-inhibited (40 ± 4%CVCmax) sites were significantly attenuated compared to control and nNOS-inhibited (P < 0.001 all conditions) but there was no difference between eNOS-inhibited and non-selective NOS-inhibited sites. These data suggest eNOS, not nNOS, mediate NO synthesis during reflex cutaneous vasodilatation with sustained dynamic exercise. PMID:25260636

McNamara, Tanner C; Keen, Jeremy T; Simmons, Grant H; Alexander, Lacy M; Wong, Brett J

2014-12-01

338

Sudden loading perturbation to determine the reflex response of different back muscles: a reliability study.  

PubMed

In this study we estimate the reliability of reflex response variables to identify the main sources of variability and to estimate appropriate measurement strategies to obtain more reliable measures. Back muscle surface electromyography (EMG) was recorded in healthy males during anteriorly-directed sudden loading perturbations applied to the trunk. Measures of EMG reflex latency and amplitude were obtained. The generalizability theory was used as a framework to estimate the magnitude of the different variance components and the reliability of the measures corresponding to various simulations of different measurement strategies. Reliability of the different variables was poor to moderate (intraclass correlation coefficient range 0-0.62). Averaging scores across homologous muscles and several trials were strategies to achieve more acceptable reliability. The reflex response of back muscles is inherently variable, and a large measurement effort is necessary to obtain reliable and, consequently, valid and responsive estimations of this neuromuscular function. PMID:21321951

Santos, Brenda R; Larivière, Christian; Delisle, Alain; McFadden, David; Plamondon, André; Imbeau, Daniel

2011-03-01

339

Saccadic compensation for reflexive optokinetic nystagmus just as good as compensation for volitional pursuit  

PubMed Central

The natural viewing behavior of moving observers ideally requires target-selecting saccades to be coordinated with automatic gaze-stabilizing eye movements such as optokinetic nystagmus. However, it is unknown whether saccade plans can compensate for reflexive movement of the eye during the variable saccade latency period, and it is unclear whether reflexive nystagmus is even accompanied by extraretinal signals carrying the eye movement information that could potentially underpin such compensation. We show that saccades do partially compensate for optokinetic nystagmus that displaces the eye during the saccade latency period. Moreover, this compensation is as good as for displacements due to voluntary smooth pursuit. In other words, the saccade system appears to be as well coordinated with reflexive nystagmus as it is with volitional pursuit, which in turn implies that extraretinal signals accompany nystagmus and are just as informative as those accompanying pursuit. PMID:25624463

Harrison, James J.; Freeman, Tom C. A.; Sumner, Petroc

2015-01-01

340

Loss of reflex tearing after maxillary orthognathic surgery: a report of two cases  

PubMed Central

Background Few reports have described the ophthalmic complications that occur after maxillary orthognathic surgery. Since cases of decreased reflex tearing after maxillary orthognathic surgery are extremely rare, we describe 2 cases of loss of reflex tearing after maxillary orthognathic surgery. Case presentation Two Asian women, an 18-year-old and a 32-year-old, suffered from unilateral dryness and irritation caused by maxillary orthognathic surgery. In both patients, Schirmer test (II) showed reduced reflex tearing in 1 eye. Computed tomography showed that the pterygoid plate had been fractured in both patients. Conclusions The pterygopalatine ganglion and its associated fibers in the pterygopalatine fossa may be injured during Le Fort osteotomy. PMID:24673800

2014-01-01

341

Cortical stimulation causes long-term changes in H-reflexes and spinal motoneuron GABA receptors  

PubMed Central

The cortex gradually modifies the spinal cord during development, throughout later life, and in response to trauma or disease. The mechanisms of this essential function are not well understood. In this study, weak electrical stimulation of rat sensorimotor cortex increased the soleus H-reflex, increased the numbers and sizes of GABAergic spinal interneurons and GABAergic terminals on soleus motoneurons, and decreased GABAA and GABAB receptor labeling in these motoneurons. Several months after the stimulation ended the interneuron and terminal increases had disappeared, but the H-reflex increase and the receptor decreases remained. The changes in GABAergic terminals and GABAB receptors accurately predicted the changes in H-reflex size. The results reveal a new long-term dimension to cortical-spinal interactions and raise new therapeutic possibilities. PMID:22933718

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

2012-01-01

342

Nasal-Ocular Reflexes and Their Role in the Management of Allergic Rhinoconjunctivitis With Intranasal Steroids  

PubMed Central

Allergic rhinitis is a common disorder and involves the reaction to environmental allergens with resultant nasal and eye symptoms. The pathophysiologic mechanisms of the eye symptoms in allergic conjunctivitis include a direct effect on the eye by deposited allergen and indirect effects related to the deposition of allergen in the nasal mucosa. One of these proposed mechanisms is the existence of a nasal-ocular reflex whereby the nasal allergic reaction leads to an afferent reflex response, the efferent limb of which results in eye symptoms. Among the treatments available for allergic rhinitis, intranasal steroids are most efficacious for nasal symptoms and have also shown sizeable efficacy related to eye symptoms. We speculated that the effect of intranasal steroids on eye symptoms in allergic rhinitis was related to their inhibition of the nasal-ocular reflex and present data previously generated from our laboratory to support this assumption in a nasal challenge model. PMID:23283068

2011-01-01

343

[The effect of transcranial electrostimulation in an analgesic regimen on somatosympathetic reflexes].  

PubMed

The mechanisms of inhibitory effect of transcranial electrostimulation in analgesic regime on blood pressor nociceptive reflexes were studied in experiments in rabbits and cats. Considerable inhibition of the late (bulbar) somato-sympathetic reflexes and spino-bulbo-spinal somato-somatic reflexes as well was demonstrated. The probable basis of sympatho-inhibition during transcranial electrical stimulation is a reduction of excitatory input to bulbar sympathoexcitatory neurons. It was revealed in experiments with inhibition of sympatho-excitation elicited by temporal brain ischaemia and local electrical stimulation of different bulbar ventrolateral vasomotor zones. The role of periaqueductal gray activated by transcranial electrical stimulation as a source of inhibition and its opioid mechanisms are discussed. PMID:1302714

Krasiukov, A V; Lebedev, V P; Katsenel'son, Ia S; Fan, A B

1992-11-01

344

Dissociative identity disorder and prepulse inhibition of the acoustic startle reflex.  

PubMed

A group of persons with dissociative identity disorder (DID) was compared with a group of persons with other dissociative disorders, and a group of nondiagnosed controls with regard to prepulse inhibition (PPI) of the acoustic startle reflex. The findings suggest maladaptive attentional processes at a controlled level, but not at a preattentive automatic level, in persons with DID. The prepulse occupied more controlled attentional resources in the DID group compared with the other two groups. Preattentive automatic processing, on the other hand, was normal in the DID group. Moreover, startle reflexes did not habituate in the DID group. In conclusion, increased PPI and delayed habituation is consistent with increased vigilance in individuals with DID. The present findings of reduced habituation of startle reflexes and increased PPI in persons with DID suggest the operation of a voluntary process that directs attention away from unpleasant or threatening stimuli. Aberrant voluntary attentional processes may thus be a defining characteristic in DID. PMID:18830396

Dale, Karl Yngvar; Flaten, Magne Arve; Elden, Ake; Holte, Arne

2008-06-01

345

Dissociative identity disorder and prepulse inhibition of the acoustic startle reflex  

PubMed Central

A group of persons with dissociative identity disorder (DID) was compared with a group of persons with other dissociative disorders, and a group of nondiagnosed controls with regard to prepulse inhibition (PPI) of the acoustic startle reflex. The findings suggest maladaptive attentional processes at a controlled level, but not at a preattentive automatic level, in persons with DID. The prepulse occupied more controlled attentional resources in the DID group compared with the other two groups. Preattentive automatic processing, on the other hand, was normal in the DID group. Moreover, startle reflexes did not habituate in the DID group. In conclusion, increased PPI and delayed habituation is consistent with increased vigilance in individuals with DID. The present findings of reduced habituation of startle reflexes and increased PPI in persons with DID suggest the operation of a voluntary process that directs attention away from unpleasant or threatening stimuli. Aberrant voluntary attentional processes may thus be a defining characteristic in DID. PMID:18830396

Dale, Karl Yngvar; Flaten, Magne Arve; Elden, Åke; Holte, Arne

2008-01-01

346

Eye gaze triggers reflexive attention shifts: Evidence from lateralised ERPs.  

PubMed

Social cues, such as another individual?s eye gaze, provide valuable information regarding the actions and intentions of others. Previous studies have suggested that seeing another?s gaze automatically orients one?s attention in the gaze direction. In this event-related potential (ERP) study, a spatial cuing paradigm was combined with a visual search task in which targets were defined by feature conjunctions in order to eliminate effects of target/distractor salience. Participants viewed centrally presented faces with neutral expressions in which eyes looked to the left or right. The participants? task was to identify a target object (with or without gap) defined by a combination of shape and orientation, which appeared in either the same (cued) or the opposite (uncued) location as the direction of the eye gaze. There was behavioural evidence of a gaze congruency effect, as reaction times (RTs) were faster when the eyes looked towards the target rather than away from the location of the target. The ERP data indicated the presence of significant gaze-congruent early directing attention negativity (EDAN) and anterior directing attention negativity (ADAN), reflecting attention shifts to the cued location in advance of the target presentation. ERP data did not show evidence of later orienting of attention triggered by gaze cues in the late attention-directing attention positivity (LDAP) at posterior sites. The results disclosed the neural response during reflexive attention shifting triggered by gazes and ascertained the relationship among EDAN, ADAN, LDAP and gaze-elicited attention shifts. After the presentation of the target array without salient stimuli, the presence of the N2-posterior-contralateral (N2pc) in the cued trials and the absence in the uncued trials further supported that attention had been directed to the possible target location prior to the target onset. The ERPs in response to the target array also extend our understanding of the neural response that orients spatial attention by providing valuable information about the temporal dynamics without the influence of salience. PMID:25241361

Feng, Qing; Zhang, Xuemin

2014-11-17

347

Ontogeny of Mouse Vestibulo-Ocular Reflex Following Genetic or Environmental Alteration of Gravity Sensing  

PubMed Central

The vestibular organs consist of complementary sensors: the semicircular canals detect rotations while the otoliths detect linear accelerations, including the constant pull of gravity. Several fundamental questions remain on how the vestibular system would develop and/or adapt to prolonged changes in gravity such as during long-term space journey. How do vestibular reflexes develop if the appropriate assembly of otoliths and semi-circular canals is perturbed? The aim of present work was to evaluate the role of gravity sensing during ontogeny of the vestibular system. In otoconia-deficient mice (ied), gravity cannot be sensed and therefore maculo-ocular reflexes (MOR) were absent. While canals-related reflexes were present, the ied deficit also led to the abnormal spatial tuning of the horizontal angular canal-related VOR. To identify putative otolith-related critical periods, normal C57Bl/6J mice were subjected to 2G hypergravity by chronic centrifugation during different periods of development or adulthood (Adult-HG) and compared to non-centrifuged (control) C57Bl/6J mice. Mice exposed to hypergravity during development had completely normal vestibulo-ocular reflexes 6 months after end of centrifugation. Adult-HG mice all displayed major abnormalities in maculo-ocular reflexe one month after return to normal gravity. During the next 5 months, adaptation to normal gravity occurred in half of the individuals. In summary, genetic suppression of gravity sensing indicated that otolith-related signals might be necessary to ensure proper functioning of canal-related vestibular reflexes. On the other hand, exposure to hypergravity during development was not sufficient to modify durably motor behaviour. Hence, 2G centrifugation during development revealed no otolith-specific critical period. PMID:22808156

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

2012-01-01

348

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

PubMed

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

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

2014-07-01

349

Reversal of functional disorders by aspiration, expiration, and cough reflexes and their voluntary counterparts  

PubMed Central

Agonal gasping provoked by asphyxia can save ~15% of mammals even from untreated ventricular fibrillation (VF), but it fails to revive infants with sudden infant death syndrome (SIDS). Our systematic study of airway reflexes in cats and other animals indicated that in addition to cough, there are two distinct airway reflexes that may contribute to auto-resuscitation. Gasp- and sniff-like spasmodic inspirations (SIs) can be elicited by nasopharyngeal stimulation, strongly activating the brainstem generator for inspiration, which is also involved in the control of gasping. This “aspiration reflex” (AspR) is characterized by SI without subsequent active expiration and can be elicited during agonal gasping, caused by brainstem trans-sections in cats. Stimulation of the larynx can activate the generator for expiration to evoke the expiration reflex (ExpR), manifesting with prompt expiration without preceding inspiration. Stimulation of the oropharynx and lower airways provokes the cough reflex (CR) which results from activating of both generators. The powerful potential of the AspR resembling auto-resuscitation by gasping can influence the control mechanisms of vital functions, mediating reversal of various functional disorders. The AspR in cats interrupted hypoxic apnea, laryngo- and bronchospasm, apneusis and even transient asphyxic coma, and can normalize various hypo- and hyper-functional disorders. Introduction of a nasogastric catheter evoked similar SIs in premature infants and interrupted hiccough attacks in adults. Coughing on demand can prevent anaphylactic shock and resuscitate the pertinent subject. Sniff representing nasal inspiratory pressure and maximal inspiratory and expiratory pressures (MIP and MEP) are voluntary counterparts of airway reflexes, and are useful for diagnosis and therapy of various cardio-respiratory and neuromuscular disorders. PMID:23248602

Tomori, Zoltan; Donic, Viliam; Benacka, Roman; Gresova, Sona; Peregrim, Igor; Kundrik, Martin; Pallayova, Maria; Jakus, Jan

2012-01-01

350

Effect of chronic intermittent hypoxia on the reflex recruitment of the genioglossus during airway obstruction in the anesthetized rat.  

PubMed

We sought to test the hypothesis that chronic intermittent hypoxia (CIH)-a feature of sleep-disordered breathing in humans-impairs reflex recruitment of the genioglossus (GG, pharyngeal dilator) during obstructive airway events. Adult male Wistar rats were exposed to 20 cycles of normoxia and hypoxia (5% O2 at nadir) per hour, 8h a day for 7 days (CIH, N=7). The sham group (N=7) were exposed to normoxia in parallel. Following gas treatments, rats were anesthetized with an i.p. injection of urethane (1.5g/kg; 20%, w/v). Fine concentric needle electrodes were inserted into the GG and the costal diaphragm. Discriminated GG motor unit potentials and whole electromyograph (EMG), together with arterial blood pressure and arterial O2 saturation, were recorded during quiet basal breathing and during nasal airway occlusion. Airway occlusion significantly increased GG EMG activity in all animals; but there was no difference in the reflex response to airway occlusion between sham and CIH-treated animals (+105±22% vs. +105±17%, mean±SEM for area under the curve of integrated GG EMG, % increase from baseline, p=0.99). Occluded breaths were characterized by a significant increase in the firing frequency of phasically active units and the recruitment of large motor units that were quiescent under basal conditions. Though there are reports of impaired control of the upper airway following CIH in the rat, we conclude that reflexly evoked motor discharge to the GG is not affected by 7 days of CIH, a paradigm that we have shown increases apnea index in sleeping rats. PMID:24746047

Edge, Deirdre; McDonald, Fiona B; Jones, James F X; Bradford, Aidan; O'Halloran, Ken D

2014-01-01

351

A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders  

NASA Technical Reports Server (NTRS)

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

Leigh, R. J.; Brandt, T.

1993-01-01

352

Nitric Oxide/cGMP-Mediated Protein Kinase A Activation in the Antennal Lobes Plays an Important Role in Appetitive Reflex  

E-print Network

Role in Appetitive Reflex Habituation in the Honeybee Uli Mu¨ ller1 and Herbert Hildebrandt2 1Institut of a reflex pathway (Thompson and Spencer, 1966; Groves and Thompson, 1970). Paradoxically, com- pared

Menzel, Randolf - Institut für Biologie

353

Distributed and Partially Separate Pools of Neurons Are Correlated with Two Different Components of the Gill-Withdrawal Reflex in  

E-print Network

of the Gill-Withdrawal Reflex in Aplysia Michal Zochowski,1,2,5 Lawrence B. Cohen,1,2 Galit Fuhrmann,2 abdominal ganglion with the movement of the gill during the gill-withdrawal reflex. We discriminated four-order sensory neurons that respond to the onset and offset of stimulation of the gill and are active before

Kleinfeld, David

354

Frontal lobe lesions in man cause difficulties in suppressing reflexive glances and in generating goal-directed saccades  

Microsoft Academic Search

Summary  The frontal eye field (FEF) and superior colliculus (SC) are thought to form two parallel systems for generating saccadic eye movements. The SC is thought classically to mediate reflex-like orienting movements. Thus it can be hypothesized that the FEF exerts a higher level control on a visual grasp reflex. To test this hypothesis we have studied the saccades of patients

D. Guitton; H. A. Buchtel; R. M. Douglas

1985-01-01

355

Politics, Knowledge and Objectivity in Sociology of Education: A Response to the Case for "Ethical Reflexivity" by Gewirtz and Cribb  

ERIC Educational Resources Information Center

The present article examines the relationship between political values and social research, with particular reference to the case for ethical reflexivity in sociology of education put forward by Gewirtz and Cribb. It is argued that their case for such reflexivity is flawed by conceptual imprecision and over-determination of the links between value…

Abraham, John

2008-01-01

356

The enhancement of learned cardiac deceleration through reflexive techniques and biofeedback  

E-print Network

of NASTER OF SCIENCE August 1976 Major Subject: Psychology THE ENHANCEMENT 0 F LEARNED CARDIAC DECELERATION THROUGH REFLEXIVE TECHNIQUES AND BIOFEEDBACK A Thesis by ARNETTE INGRAM Approved as to sty1e and content by: (Chairman of Co ittee) (Head... of Department) (Mem er) (Member) August 1 976 ABSTRACT The Enhancement of Learned Cardiac Decelerat1on through Reflexive Techniques And Biofeedback. (August 1976) Arnette Ingram, B. A. , St. I'4ary's University Chairman of Adv1sory Comm1ttee: Dr. A. E...

Ingram, Arnette

1976-01-01

357

Visual suppression of the vestibulo-ocular reflex during space flight  

NASA Technical Reports Server (NTRS)

Visual suppression of the vestibulo-ocular reflex was studied in 16 subjects on 4 Space Shuttle missions. Eye movements were recorded by electro-oculography while subjects fixated a head mounted target during active sinusoidal head oscillation at 0.3 Hz. Adequacy of suppression was evaluated by the number of nystagmus beats, the mean amplitude of each beat, and the cumulative amplitude of nystagmus during two head oscillation cycles. Vestibulo-ocular reflex suppression was unaffected by space flight. Subjects with space motion sickness during flight had significantly more nystagmus beats than unaffected individuals. These susceptible subjects also tended to have more nystagmus beats before flight.

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

1989-01-01

358

Effect of unilateral vestibular deafferentation on the initial human vestibulo-ocular reflex to surge translation  

PubMed Central

Transient whole-body surge (fore-aft) translation at 0.5 G peak acceleration was administered to six subjects with unilateral vestibular deafferentation (UVD), and eight age-matched controls. Subjects viewed eccentric targets to determine if linear vestibulo-ocular reflex (LVOR) asymmetry might lateralize otolith deficits. Eye rotation was measured using magnetic search coils. Immediately before surge, subjects viewed a luminous target 50 cm away, centered or displaced 10° horizontally or vertically. The target was extinguished during randomly directed surges. LVOR gain relative to ideal velocity in subjects with UVD for the contralesional horizontally eccentric target (0.59 ± 0.08, mean ± SEM) did not differ significantly from normal (0.50 ± 0.04), but gain for the ipsilesional eccentric target (0.35 ± 0.02) was significantly less than normal (0.48 ± 0.03, P < 0.05). Normal subjects had mean gain asymmetry for horizontally eccentric targets of 0.17 ± 0.03, but asymmetry in UVD was significantly increased to 0.35 ± 0.05 (P < 0.05). Four of six subjects with UVD had maximum gain asymmetry outside normal 95% confidence limits. Asymmetry did not correlate with UVD duration. Gain for 10° vertically eccentric targets averaged 0.38 ± 0.14 for subjects with UVD, insignificantly lower than the normal value of 0.75 ± 0.15 (P > 0.05). Surge LVOR latency was symmetrical in UVD, and did not differ significantly from normal. There was no significant difference in response between dark and visible target conditions until 200 ms after surge onset. Chronic human UVD, on average, significantly impairs the surge LVOR for horizontally eccentric targets placed ipsilesionally, but this asymmetry is small relative to interindividual variation. PMID:16900361

Tian, Jun-Ru; Ishiyama, Akira; Demer, Joseph L.

2007-01-01

359

Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex  

NASA Technical Reports Server (NTRS)

The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head movements.

Trillenberg, P.; Shelhamer, M.; Roberts, D. C.; Zee, D. S.

2003-01-01

360

Kinematics of Vertical Saccades during the Yaw Vestibulo-ocular Reflex in Humans  

PubMed Central

Purpose Listing’s law (LL) constrains the rotational axes of saccades and pursuit eye movements to Listing’s plane (LP). In the velocity domain, LL is ordinarily equivalent to a tilt in the ocular velocity axis equal to half the change in eye position, giving a tilt angle ratio (TAR) of 0.5. This study was undertaken to investigate vertical saccade behavior after the yaw vestibulo-ocular reflex (VOR) had driven eye torsion out of LP, an initial condition causing the position and velocity domain formulations of LL to differ. Methods Binocular eye and head motions were recorded with magnetic search coils in eight humans. With the head immobile, LP was determined for each eye, and mean TAR was 0.50 ± 0.07 (mean ± SD) for horizontal and 0.45 ± 0.11 for vertical saccades. The VOR was evoked by transient, whole-body yaw at 2800 deg/s2 peak acceleration, capable of evoking large, uninterrupted VOR slow phases. Before rotation, subjects viewed a target at eye level, 20° up, or 20° down. In two thirds of the trials, the target moved upward or downward at systematically varying times, triggering a vertical saccade during the horizontal VOR slow phase. Results Because the head rotation axis was generally misaligned with LP, the eye averaged 3.6° out of LP at vertical saccade onset. During the saccade, eye position continued to depart LP by an average 0.8°. The horizontal TAR at saccade onset was 0.29 ± 0.07. At peak saccade velocity 35 ± 3 ms later, the vertical TAR was 0.45 ± 0.07, statistically similar to that of head fixed saccades. Saccades did not return to LP. Conclusions Although they did not observe the position domain formulation of LL, vertical saccades, during the VOR, observed the half-angle velocity domain formulation of LL. PMID:16043853

Crane, Benjamin T.; Tian, Junru; Demer, Joseph L.

2007-01-01

361

Measuring in-the-ear gain of hearing aids by the acoustic reflex method.  

PubMed

The gain of hearing aids is conventionally measured in a hard-walled 2-cc coupler. It has become increasingly apparent, however, that many interacting variables can affect the aid's behavior in an individual ear quite significantly. Therefore it is desirable that any departure from coupler response be known. A number of methods have been used to measure real-ear gain, some of which require expensive or nonstandard instrumentation. An alternative method is described, based on measurements of aided and unaided acoustic reflect thresholds that appears to have certain advantages over other methods. Sound-field intra-aural reflex thresholds for six one-third-octave noise bands were determined for 20 subjects using a postauricular aid under three conditions--unaided, aided/ear occluded, and aided/ear nonoccluded. Real-ear gain was defined as the difference in decibels between aided and unaided thresholds. Results showed wide individual differences in real-ear response. Average occluded real-ear gain was about 5 dB greater at 1.6 k Hz, and about 5 dB less at 3.15 k Hz, than the gain in the artificial ear. When the aid was coupled to the open ear, average real-ear response was down at all frequencies relative to the 2-cc coupler, although relative to the closed-ear response frequencies above 1.6 k Hz were emphasized. It is argued that real-ear response can be expected to vary considerably depending on the location and orientation of the microphone of the aid on the head or body. It is suggested therefore that real-ear measurements be part of every aid selection procedure, especially for persons with a reduced dynamic range. Response modifications might then be possible to enable the critical speech frequencies to be heard at a comfortable level. PMID:1127901

Tonisson, W

1975-03-01

362

Motor dysfunction and reflex sympathetic dystrophy. Bilateral motor denervation in an experimental model.  

PubMed

Reflex sympathetic dystrophy (RSD) is a neuropathic pain condition most often occurring in relation to trauma to, or surgery on, an extremity. It is characterized among other things by motor disturbances such as joint stiffness and tremor. Signs and symptoms can be induced in a rat model through chronic constriction of a sciatic nerve (CCI-model). In this study the CCI-model was used to evaluate the extent of bilateral peripheral motor nerve-fiber involvement in relation to ligature localization. In 12 Lewis rats, the common sciatic nerve was loosely ligated with four chromic catgut ligatures at the midthigh level just proximal to the right sciatic trifurcation. Acetylcholinesterase (CE) histochemistry of sciatic (distal and proximal to ligation) and corresponding contralateral nerve biopsy specimens was performed at 21 days after ligation. An additional 12 rats were sham-operated and served as controls. As compared to sham-operated controls or contralateral nonligated sciatic nerves, CE histochemistry after 21 days revealed a marked decrease of CE-positive fibers in cross-sections taken from distal and proximal sciatic nerve biopsies ipsilateral to the ligatures. In addition, as compared to sham-operated controls, there was a decrease of CE-positive fibers in cross-sections taken from contralateral nonligated sciatic nerves. The present findings indicate profound motor denervation, distal as well as proximal to the ligatures. Motor denervation also affected the contralateral nonligated sciatic nerve. The evident usefulness of the CCI-model for the study of RSD places the present results in line with the concept of central nervous system involvement in the pathophysiology of RSD. PMID:9689764

Bullens, P; Daemen, M; Freling, G; Kitslaar, P; Van den Wildenberg, F; Kurvers, H

1998-06-01

363

Paradoxical withdrawal of reflex vasoconstriction as a cause of hemodialysis-induced hypotension.  

PubMed Central

Acute hypotension is an important complication of hemodialysis, but the underlying mechanisms remain poorly understood. Because hemorrhage-induced hypovolemia can trigger a sudden decrease in sympathetic activity resulting in bradycardia and vasodilation, we hypothesized that hemodialysis-induced hypovolemia also can trigger the same type of vasodepressor reaction, which would exacerbate the volume-dependent fall in blood pressure. We therefore measured blood pressure, vascular resistance, and sympathetic nerve activity (intraneural microelectrodes) during sessions of maintenance hemodialysis in 7 patients with and 16 patients without a history of hemodialysis-induced hypotension. During hemodialysis, blood pressure at first remained unchanged as calf resistance increased in both hypotension-resistant (from 37 +/- 4 to 49 +/- 5 U, P < 0.05) and hypotension-prone (from 42 +/- 6 to 66 +/- 12 U, P < 0.05) patients; sympathetic activity increased comparably in the subset of patients in whom it could be measured. With continued hemodialysis, calf resistance and sympathetic activity increased further in the hypotension-resistant patients, but in the hypotension-prone patients the precipitous decrease in blood pressure was accompanied by decreases in sympathetic activity, vascular resistance, and heart rate as well as symptoms of vasodepressor syncope. On an interdialysis day, both groups of patients increased vascular resistance normally during unloading of cardiopulmonary baroreceptors with lower body negative pressure and increased heart rate normally during unloading of arterial baroreceptors with infusion of nitroprusside. These findings indicate that in a group of hemodialysis patients without diabetes or other conditions known to impair autonomic reflexes, hemodialysis-induced hypotension is not caused by chronic uremic impairment in arterial or cardiopulmonary baroreflexes but rather by acute, paradoxical withdrawal of sympathetic vasoconstrictor drive producing vasodepressor syncope. Images PMID:1430196

Converse, R L; Jacobsen, T N; Jost, C M; Toto, R D; Grayburn, P A; Obregon, T M; Fouad-Tarazi, F; Victor, R G

1992-01-01

364

Indian red scorpion ( Buthus tamulus) venom-induced augmentation of cardiac reflexes is mediated through the mechanisms involving kinins in urethane anaesthetized rats  

Microsoft Academic Search

The mechanism underlying the action of Indian red scorpion (Buthus tamulus; BT) venom on cardiac reflexes was examined in urethane anaesthetized adult albino rats of either sex. Intravenous injection of phenyldiguanide (PDG) produced reflex hypotension, bradycardia and apnea lasting for >60s. The PDG-induced reflex responses (blood pressure, heart rate and respiration) were augmented greatly (magnitude and time period) after exposure

Sovan Bagchi; Shripad B. Deshpande

1998-01-01

365

The human startle reflex and alcohol cue reactivity: Effects of early versus late abstinence  

Microsoft Academic Search

This study investigated the human eyeblink startle reflex as a measure of alcohol cue reactivity. Alcohol-dependent participants early (n 36) and late (n 34) in abstinence received presentations of alcohol and water cues. Consistent with previous research, greater salivation and higher ratings of urge to drink occurred in response to the alcohol cues. Differential salivary and urge responding to alcohol

Michael E. Saladin; David J. Drobes; Julian M. Libet; Scott F. Coffey

2002-01-01

366

Bourdieu Knew More than How to Play Tennis! An Empirically Based Discussion of Habituation and Reflexivity  

ERIC Educational Resources Information Center

This paper explores the role of reflexivity in habituation by contrasting the learning of aerobics and basketball with the acquisition of gendered bodily skills. The discussion is inspired by the paper "So, how did Bourdieu learn to play tennis? Habitus, consciousness and habituation," by Noble and Watkins (2003), which represents a…

Strandbu, Åse; Steen-Johnsen, Kari

2014-01-01

367

Vestibulo-ocular reflex and optokinetic nystagmus in adult cats reared in stroboscopic illumination  

Microsoft Academic Search

Cats reared in stroboscopic illumination (strobe reared cats) have been found to have abnormal eye movements. Visual and vestibular evoked compensatory eye movements were inefficient. Vestibuloocular reflex in the dark had a maximum gain of 0.6 (1.0 in normal animals). Optokinetic nystagmus had a mean gain which approached unity only at stimulus velocities around 7 °\\/s (up to 30 °\\/s

H. Kennedy; J. H. Courjon; J. M. Flandrin

1982-01-01

368

Dream Interpretation as a Component of Researcher's Reflexivity within an Ethnographic Research  

ERIC Educational Resources Information Center

Researchers' "reflexivity" about how they shape the phenomena that they study within the data collection process is often presented as a crucial component of ethnographic research methodology. Nevertheless, academic literature about ethnography is mostly silent around whether researchers' dreams are relevant to the research…

Miškolci, Jozef

2015-01-01

369

Structural and Semantic Constraints on the Resolution of Pronouns and Reflexives  

ERIC Educational Resources Information Center

We present four experiments on the interpretation of pronouns and reflexives in picture noun phrases with and without possessors (e.g. "Andrew's picture of him/himself, the picture of him/himself"). The experiments (two off-line studies and two visual-world eye-tracking experiments) investigate how syntactic and semantic factors guide the…

Kaiser, Elsi; Runner, Jeffrey T.; Sussman, Rachel S.; Tanenhaus, Michael K.

2009-01-01

370

Microinjections of vasopressin in the locus coeruleus complex affect posture and vestibulospinal reflexes in decerebrate cats  

Microsoft Academic Search

Vasopressin (VP) acts as a neurotransmitter or a neuromodulator on noradrenergic locus coeruleus (LC) neurons by exciting them. Experiments were performed in precollicular decerebrate cats to investigate whether direct infusion of VP into the LC complex of one side produced changes in posture as well as in the gain of vestibulospinal reflexes acting on forelimb extensors. Unilateral microinjection of 0.25

P. Andre; P. d'Ascanio; M. Ioffe; O. Pompeiano

1992-01-01

371

Inclusive Education: Pre-Service Teachers' Reflexive Learning on Diversity and Their Challenging Role  

ERIC Educational Resources Information Center

Today people from a wide range of socio-cultural backgrounds are entering the teaching profession. The changing profile of pre-service teachers prompted inquiry into personal and professional influences in understanding diversity and inclusive practices. Two teacher educators collaborated across Australian universities to explore reflexive

Bentley-Williams, Robyn; Morgan, Jennifer

2013-01-01

372

The inflammatory reflex and risk for rheumatoid arthritis: a case–control study of human vagotomy  

Microsoft Academic Search

Recent data suggest remarkable effects of vagus stimulation (reduction) and vagotomy (exacerbation) on acute inflammation in rats, the so-called “inflammatory reflex”. Its role in humans remains unknown. Therefore, the aim was to explore whether surgical vagotomy in humans would affect the risk of a prototype inflammatory disease, rheumatoid arthritis. This was a case–control study. Assessment of the relative risk (RR)

Cecilia Carlens; Lena Brandt; Lars Klareskog; Jon Lampa; Johan Askling

2007-01-01

373

Role of the central monoaminergic mechanisms in the action of drugs on the cardiac reflexes  

Microsoft Academic Search

hic recording of the tonic activity and the reflex responses in the cardiac sympathetic nerves. For this purpose, in experiments on anesthetized cats, after thoracotomy the efferent impulses were recorded in the central end of the divided left inferior cardiac nerve. The central end of the divided tibial nerve was stimulated with rectangular electric pulses. The parameters of the stimuli

N. V. Kaverina; R. S. Mirzoyan; Yu. B. Rozonov

1967-01-01

374

Reduced stretch-reflex sensitivity after exhausting stretch-shortening cycle exercise  

Microsoft Academic Search

The stretch-shortening cycle (SSC) is an effective and natural form of muscle function but, when repeated with sufficient intensity or duration, it may lead to muscle damage and functional defects. A reduced tolerance to impact has been reported, which may be partly attributed to a reduced stretch-reflex potentiation. The aim of the present study was to examine the influence of

P. V. Komi; T. Horita; H. Kyröläinen; T. E. S. Takala; C. Nicol

1996-01-01

375

Central ghrelin inhibits reflex swallowing elicited by activation of the superior laryngeal nerve in the rat  

Microsoft Academic Search

The effect of ghrelin on rhythmic reflex swallowing was examined in urethane–chloralose anesthetized rats. Swallowing was monitored by recording electromyographic activities of the suprahyoid muscle. Fourth ventricular administration of ghrelin decreased swallowing frequency during electrical stimulation of the central cut end of the superior laryngeal nerve (SLN stimulation). A significant decrease in swallowing frequency was observed after ghrelin administration at

Motoi Kobashi; Song-Yu Xuan; Masako Fujita; Yoshihiro Mitoh; Ryuji Matsuo

2010-01-01

376

Simulating Reflex Induced Changes in the Acoustic Impedance of the Ear.  

ERIC Educational Resources Information Center

A simple procedure for measuring changes in the acoustic impedance of the ear is described. The technique has several applications, including simulation using a standard coupler of changes in real ear impedance produced by the acoustic reflex, and calibration of response time of an otoadmittance meter. (Author/DB)

Sirlin, Mindy W.; Levitt, Harry

1991-01-01

377

Enhancing informality as an opportunity for the reflexivity of social sciences  

E-print Network

of informality regarding social sciences ­ it might not be that new ­, and it makes 1 Enhancing informality as an opportunity for the reflexivity of social sciences 5th Meeting of RECIM network (ENS ­ Lyon; January 2012, 16th ­ 17th

Paris-Sud XI, Université de

378

Parallel Reflex and Central Control of Promotor and Receptor Motorneurons in Crayfish  

Microsoft Academic Search

We describe the reflex and central control of an identified motorneuron (rml) to a crayfish muscle receptor, the thoracocoxal muscle receptor organ (TCMRO), and compare it with the in-parallel, `extrafusal' promotor motorneurons. Rml is spontaneously active in an isolated preparation. This activity is modulated in phase with centrally driven promotor nerve activity, suggesting coactivation of promotor and receptor-motor motorneurons. Rml

Peter Skorupski; Brian M. H. Bush

1992-01-01

379

Neither Shaking nor Stirring: A Case Study of Reflexivity in Norwegian Physical Education Teacher Education  

ERIC Educational Resources Information Center

This paper examines the place of reflexivity in the "philosophies" and practices of physical education (PE) teacher educators in Norway. Using a case study approach to one quite typical institution delivering physical education teacher education (PETE) in Norway, semi-structured interviews were conducted with 15 teacher educators.…

Mordal-Moen, Kjersti; Green, Ken

2014-01-01

380

Emergent Identity Matching after Successive Matching Training, I: Reflexivity or Generalized Identity?  

ERIC Educational Resources Information Center

This research investigated the source of an ostensible reflexivity effect in pigeons reported by Sweeney and Urcuioli (2010). In Experiment 1, pigeons learned two symmetrically reinforced symbolic successive matching tasks (hue-form and form-hue) using red-green and triangle-horizontal line stimuli. They differed in their third concurrently…

Urcuioli, Peter J.

2011-01-01

381

Cardiac nociceptive reflexes after transmyocardial laser revascularization: Implications for the neural hypothesis of angina relief  

Microsoft Academic Search

Objective: The mechanism by which transmyocardial laser revascularization relieves angina is not understood. One theory is that laser-induced thermal damage to cardiac nerves results in cardiac denervation. This study examined the acute effects of transmyocardial laser revascularization on reflex responses mediated by cardiac nociceptors, the left ventricular receptors with sympathetic afferent fibers that are thought to mediate anginal chest pain.

Anthony J. Minisi; On Topaz; M. Susan Quinn; Laxmi B. Mohanty

2001-01-01

382

For a public sociology on participatory democracy Reflexive feedback on a research conducted in an association  

E-print Network

1 For a public sociology on participatory democracy Reflexive feedback on a research conducted on the research methods and the results and, vice versa, the role of sociology1 in the development Burawoy entitled "For public sociology" (2005), who fuelled many debates across the Atlantic on the social

Boyer, Edmond

383

Interaction between vestibulosympathetic and skeletal muscle reflexes on sympathetic activity in humans  

NASA Technical Reports Server (NTRS)

Evidence from animals indicates that skeletal muscle afferents activate the vestibular nuclei and that both vestibular and skeletal muscle afferents have inputs to the ventrolateral medulla. The purpose of the present study was to investigate the interaction between the vestibulosympathetic and skeletal muscle reflexes on muscle sympathetic nerve activity (MSNA) and arterial pressure in humans. MSNA, arterial pressure, and heart rate were measured in 17 healthy subjects in the prone position during three experimental trials. The three trials were 2 min of 1) head-down rotation (HDR) to engage the vestibulosympathetic reflex, 2) isometric handgrip (IHG) at 30% maximal voluntary contraction to activate skeletal muscle afferents, and 3) HDR and IHG performed simultaneously. The order of the three trials was randomized. HDR and IHG performed alone increased total MSNA by 46 +/- 16 and 77 +/- 24 units, respectively (P < 0.01). During the HDR plus IHG trial, MSNA increased 142 +/- 38 units (P < 0.01). This increase was not significantly different from the sum of the individual trials (130 +/- 41 units). This finding was also observed with mean arterial pressure (sum = 21 +/- 2 mmHg and HDR + IHG = 22 +/- 2 mmHg). These findings suggest that there is an additive interaction for MSNA and arterial pressure when the vestibulosympathetic and skeletal muscle reflexes are engaged simultaneously in humans. Therefore, no central modulation exists between these two reflexes with regard to MSNA output in humans.

Ray, C. A.

2001-01-01

384

1) The motor system -an overall 2) Spinal reflexes and circuitry  

E-print Network

1 1) The motor system - an overall view 2) Spinal reflexes and circuitry 3) Brainstem pathways Topic 6 ­ Organization of Motor System - Spinal and Brainstem Circuitry Sensory systems - Physical;2 Brainstem The motor system - an overall view Source: Kandel et al., Principles of Neural Science, Mc

Sergio, Lauren E.

385

The Limits of Children's Voices: From Authenticity to Critical, Reflexive Representation  

ERIC Educational Resources Information Center

This article provides a critique of the preoccupation with children's voices in child-centred research by exploring their limits and problematizing their use in research. The article argues that critical, reflexive researchers need to reflect on the processes which produce children's voices in research, the power imbalances that shape them and the…

Spyrou, Spyros

2011-01-01

386

Maintaining Interaction at the Zone of Proximal Development through Reflexive Practice and Action Research  

ERIC Educational Resources Information Center

In this study, dialectical reflexive practice is used to maintain student-teacher interactions in the zone of proximal development. The zone of proximal development is the development-and-learning unit of the child or learner and the author suggests that it is also the fusion point of Marx's dialectical historical materialism: the creation of…

Lisle, Angela

2006-01-01

387

An Existentialist in Iqaluit: Existentialism and Reflexivity Informing Pedagogy in the Canadian North  

ERIC Educational Resources Information Center

Reflecting on the personal experience of teaching human resource management in the Canadian Arctic, the author explores the utility of an existentialist approach to pedagogy. The author outlines select aspects of existentialism that are pertinent to the teaching and discusses the implications of using reflexive existential thought as guidance in a…

Yue, Anthony R.

2011-01-01

388

Anomalous behavior of neutron refraction index in a perfect crystal near the Bragg reflex  

NASA Astrophysics Data System (ADS)

Anomalous behavior of neutron refraction index in a perfect crystal near Bragg resonance was studied. This phenomenon is connected with the resonance behavior of potential of neutron interaction with crystal near the Bragg reflex. The amplitude of this resonance is equal to magnitude of g-harmonic of neutron interaction potential Vg and width is about the Bragg width of reflex. Recently, it was shown that for the case of noncentrosymmetric crystal this effect result in a large electric field acting on a neutron (value of the field can reach about 108V/cm) . This effect is planed using to search for the electric dipole moment of a neutron. If the degree of crystal imperfect is less than the Bragg reflection width (case of perfect crystal) the width of the reflex is determined by the own width of crystal reflex that is about 10?5 of the neutron energy. The value of g-harmonics of interaction of neutron with crystal Vg and optical potential of the interaction of neutron with crystal V0 are usually about the same. Therefore the variation of neutron energy on a 10?5 of its value will change significantly a potential of neutron interaction with crystal.

Lasitsa, M. V.; Braginetz, Yu P.; Vezhlev, E. O.; Semenikhin, S. Yu; Kuznetsov, I. A.; Fedorov, V. V.; Voronin, V. V.

2014-12-01

389

Association Between In Utero Organophosphate Pesticide Exposure and Abnormal Reflexes in Neonates  

Microsoft Academic Search

The detrimental effects of organophosphate pesticide (OP) exposure on neurodevelopment have been shown in animals. The present study aimed to assess the relationship between in utero and early postnatal OP exposure and neonatal neurobehavior in humans, as measured by seven clusters (habituation, orientation, motor performance, range of state, regulation of state, autonomic stability, and reflex) on the Brazelton Neonatal Behavioral

Jessica G. Young; Brenda Eskenazi; Eleanor A. Gladstone; Asa Bradman; Lesley Pedersen; Caroline Johnson; Dana B. Barr; Clement E. Furlong; Nina T. Holland

2005-01-01

390

The bedside examination of the vestibulo-ocular reflex (VOR): An update  

PubMed Central

Diagnosing dizzy patients remains a daunting challenge to the clinician in spite of modern imaging and increasingly sophisticated electrophysiological testing. Here we review the major bedside tests of the vestibulo-ocular reflex and how, when combined with a proper examination of the other eye movement systems, one can arrive at an accurate vestibular diagnosis. PMID:22981296

Kheradmand, A.; Zee, D.S.

2014-01-01

391

Human papillomavirus ‘reflex’ testing as a screening method in cases of minor cytological abnormalities  

Microsoft Academic Search

The aim was to evaluate human papillomavirus (HPV) ‘reflex genotyping’ in cases of minor cytological abnormalities detected in the gynaecological screening programme in Stockholm, Sweden. Liquid-based cytology samples showing minor cytological abnormalities were analysed using HPV genotyping (Linear Array, Roche diagnostics). Colposcopically directed cervical biopsies were obtained and the HPV test results were correlated with the histological results. In all,

M Fröberg; B Johansson; A Hjerpe; S Andersson

2008-01-01

392

Biting intentions modulate digastric reflex responses to sudden unloading of the jaw.  

PubMed

Reflex responses in jaw-opening muscles can be evoked when a brittle object cracks between the teeth and suddenly unloads the jaw. We hypothesized that this reflex response is flexible and, as such, is modulated according to the instructed goal of biting through an object. Study participants performed two different biting tasks when holding a peanut half stacked on a chocolate piece between their incisors. In one task, they were asked to split the peanut half only (single-split task), and in the other task, they were asked to split both the peanut and the chocolate in one action (double-split task). In both tasks, the peanut split evoked a jaw-opening muscle response, quantified from electromyogram (EMG) recordings of the digastric muscle in a window 20-60 ms following peanut split. Consistent with our hypothesis, we found that the jaw-opening muscle response in the single-split trials was about twice the size of the jaw-opening muscle response in the double-split trials. A linear model that predicted the jaw-opening muscle response on a single-trial basis indicated that task settings played a significant role in this modulation but also that the presplit digastric muscle activity contributed to the modulation. These findings demonstrate that, like reflex responses to mechanical perturbations in limb muscles, reflex responses in jaw muscles not only show gain-scaling but also are modulated by subject intent. PMID:24899675

Johansson, Anders S; Pruszynski, J Andrew; Edin, Benoni B; Westberg, Karl-Gunnar

2014-09-01

393

Labour Market Mismatch among UK Graduates: An Analysis Using REFLEX Data  

ERIC Educational Resources Information Center

There is much disagreement in the literature over the extent to which graduates are mismatched in the labour market and the reasons for this. In this paper we utilise the Flexible Professional in the Knowledge Society (REFLEX) data set to cast light on these issues, based on data for UK graduates. We find substantial pay penalties for…

McGuinness, Seamus; Sloane, Peter J.

2011-01-01

394

The Reflexive Producer: The Influence of Farmer Knowledge upon the Use of Bt Corn  

ERIC Educational Resources Information Center

This paper examines the influence of farmer knowledge upon decision making processes. Drawing upon the sociological debates around the ideas of reflexive modernity and biotechnology as well as from classic adoption and diffusion studies, I explore the influences upon farmers' use of "Bacillus thuringiensis" (Bt) corn. Utilizing survey data…

Kaup, Brent Z.

2008-01-01

395

The Suppression of Reflexive Visual and Auditory Orienting when Attention Is Otherwise Engaged  

ERIC Educational Resources Information Center

Two experiments were conducted to examine whether abrupt onsets are capable of reflexively capturing attention when they occur outside the current focus of spatial attention, as would be expected if exogenous orienting operates in a truly automatic fashion. The authors established a highly focused attentional state by means of the central…

Santangelo, Valerio; Olivetti Belardinelli, Marta; Spence, Charles

2007-01-01

396

Reflex human papillomavirus deoxyribonucleic acid testing in women with abnormal Papanicolaou smears  

Microsoft Academic Search

OBJECTIVE: The study examined interrelationships between sensitivity and specificity of “reflex human papillomavirus deoxyribonucleic acid testing” from liquid-based cervical cytologic specimens by means of receiver operator characteristics curves. STUDY DESIGN: A cohort study was performed on 265 women evaluated by colposcopy because of atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion found on Papanicolaou smear. RESULTS: At

Thomas C. Wright Jr.; Attila Lorincz; Daron G. Ferris; Ralph M. Richart; Alex Ferenczy; Iwona Mielzynska; Lynn Borgatta

1998-01-01

397

Resolving conflicting views: Gaze and arrow cues do not trigger rapid reflexive shifts of attention  

E-print Network

correspondence to Jessica Green, Assistant Professor, Department of Psychology, Rm. 414, 1512 Pendleton StResolving conflicting views: Gaze and arrow cues do not trigger rapid reflexive shifts of attention, Duke University, Durham, NC, USA 2 Department of Psychology and Neuroscience, Duke University, Durham

398

Structural and semantic constraints on the resolution of pronouns and reflexives  

PubMed Central

We present four experiments on the interpretation of pronouns and reflexives in picture noun phrases with and without possessors (e.g. Andrew’s picture of him/himself, the picture of him/himself). The experiments (two off-line studies and two visual-world eye-tracking experiments) investigate how syntactic and semantic factors guide the interpretation of pronouns and reflexives and how different kinds of information are integrated during real-time reference resolution. The results show that the interpretation of pronouns and reflexives in picture NP constructions is sensitive not only to purely structural information, as is commonly assumed in syntactically-oriented theories of anaphor resolution, but also to semantic information (see Kuno, 1987; Tenny, 2003). Moreover, the results show that pronouns and reflexives differ in the degree of sensitivity they exhibit to different kinds of information. This finding indicates that the form-specific multiple-constraints approach (see Kaiser, 2003; Kaiser, 2005; Kaiser & Trueswell, 2008; Brown-Schmidt, Byron & Tanenhaus, 2005), which states that referential forms can exhibit asymmetrical sensitivities to the different constraints guiding reference resolution, also applies in the within-sentence domain. PMID:19426968

Kaiser, Elsi; Runner, Jeffrey T.; Sussman, Rachel S.; Tanenhaus, Michael K.

2009-01-01

399

Using Stimulation of the Diving Reflex in Humans to Teach Integrative Physiology  

ERIC Educational Resources Information Center

During underwater submersion, the body responds by conserving O[subscript 2] and prioritizing blood flow to the brain and heart. These physiological adjustments, which involve the nervous, cardiovascular, and respiratory systems, are known as the diving response and provide an ideal example of integrative physiology. The diving reflex can be…

Choate, Julia K.; Denton, Kate M.; Evans, Roger G.; Hodgson, Yvonne

2014-01-01

400

Emergent Identity Matching after Successive Matching Training. II: Reflexivity or Transitivity?  

ERIC Educational Resources Information Center

Three experiments evaluated whether the apparent reflexivity effect reported by Sweeney and Urcuioli (2010) for pigeons might, in fact, be transitivity. In Experiment 1, pigeons learned symmetrically reinforced hue-form (A-B) and form-hue (B-A) successive matching. Those also trained on form-form (B-B) matching responded more to hue comparisons…

Urcuioli, Peter J.; Swisher, Melissa

2012-01-01

401

The Application of Reflexivity in Small Business Research and Implications for the Business Practitioner  

ERIC Educational Resources Information Center

This paper is based on a review of the lead author's research, which took the form of a self-narrative from a practitioner about the perceived realities of one small business and its owner. The paper explores the practical application of auto-ethnographic reflexive research methodologies and seeks to demonstrate that structured ways can be…

Harrison, Nigel; Kirkham, Janet

2014-01-01

402

Respiratory Neurons Mediating the Breuer-Hering Reflex Prolongation of Expiration in Rat  

Microsoft Academic Search

Afferent input from pulmonary stretch receptors is important in the control of the timing of inspiratory and expiratory phases of the respiratory cycle. The current study was undertaken to identify neurons within a column of respiratory neurons in the ventrolateral medulla (termed the ventral respiratory group, VRG) that, when activated by lung inflation, produce the Breuer-Hering (BH) reflex in which

Fumiaki Hayashi; Sharon K. Coles; Donald R. McCrimmon

1996-01-01

403

Acoustic startle reflex in schizophrenia patients and their first-degree relatives: Evidence of  

E-print Network

Acoustic startle reflex in schizophrenia patients and their first-degree relatives: Evidence schizophrenia patients, 48 of their first-degree relatives, and 56 controls to determine if abnormal affective startle modulation could be associated with genetic risk for schizophrenia. Both patients and relatives

Curtis, Clayton

404

The Use of Reflexive Photography in the Study of the Freshman Year Experience.  

ERIC Educational Resources Information Center

This study used reflexive photography to examine the perceptions of college freshmen at the University of Southern Indiana. A random sample of 10 first-time, full-time, degree-seeking freshmen completed an initial interview and background questionnaire and were given a 27-exposure disposable camera to take pictures that would illustrate their…

Harrington, Charles; Lindy, Ingrid

405

Higher Education's Self-Reflexive Turn: Toward an Intercultural Theory of Student Development.  

ERIC Educational Resources Information Center

Submits survey instruments on college student development used by Tinto, Astin, and Pace to five probes from recent social theory--voice, power, authenticity, self-reflexivity, and reconstitution--and proposes a shift in focus in student development research from essentialized categories like culture and race to relation and learning "between"…

Tanaka, Greg

2002-01-01

406

Variable Foreperiod Deficits in Parkinson's Disease: Dissociation across Reflexive and Voluntary Behaviors  

ERIC Educational Resources Information Center

The effect of a visual warning signal (1.0-6.5s random foreperiod, FP) on the latency of voluntary (hand-grip) and reflexive (startle-eyeblink) reactions was investigated in Parkinson's disease (PD) patients and in young and aged control subjects. Equivalent FP effects on blink were observed across groups. By contrast, FP effects diverged for…

Jurkowski, A.J.; Stepp, E.; Hackley, S.A.

2005-01-01

407

A positive Babinski reflex predicts delayed neuropsychiatric sequelae in Chinese patients with carbon monoxide poisoning.  

PubMed

As the human population increased in China, the carbon monoxide is a serious environmental toxin in public health. However, predicting the delayed neuropsychiatric sequelae (DNS) of carbon monoxide poisoning (COP) has not been well studied. We investigated the independent predictors of DNS in patients with COP. This study was conducted at four hospitals in China. Data were retrospectively collected from 258 patients with COP between November 1990 and October 2011. DNS was the primary endpoint. A positive Babinski reflex was the independent predictor for DNS: sensitivity = 53.8% (95% confidence interval [CI]: 26.1-79.6), specificity = 88.6% (95% CI: 83.7-92.1), positive predictive value (PPV) = 20.0% (95% CI: 9.1-37.5), and negative predictive value (NPV) = 97.3% (95% CI: 94.0-98.9). The area under the receiver operating characteristic curve = 0.712 (95% CI: 0.544-0.880). A positive Babinski reflex was very memorable, immediately available, and applicable in clinical practice. Even when the sensitivity and PPV of a positive Babinski reflex were unsatisfactory, it had a good specificity and NPV for excluding the risk of DNS. In patients without a positive Babinski reflex, the risk for DNS was only 2.7%. This finding may help physicians make decisions about dispositions for patients with COP. PMID:24959589

Zou, Jian-Fang; Guo, Qiming; Shao, Hua; Li, Bin; Du, Yuxiu; Liu, Maofeng; Liu, Fengling; Dai, Lixin; Chung, Min-Hsien; Lin, Hung-Jung; Guo, How-Ran; Yang, Tzu-Meng; Huang, Chien-Cheng; Hsu, Chien-Chin

2014-01-01

408

The Suppression of Reflexive Visual and Auditory Orienting When Attention Is Otherwise Engaged  

Microsoft Academic Search

Two experiments were conducted to examine whether abrupt onsets are capable of reflexively capturing attention when they occur outside the current focus of spatial attention, as would be expected if exogenous orienting operates in a truly automatic fashion. The authors established a highly focused attentional state by means of the central presentation of a stream of visual or auditory characters,

Valerio Santangelo; Marta Olivetti Belardinelli; Charles Spence

2007-01-01

409

Direction-specific optokinetic modulation of monosynaptic hind limb reflexes in cats.  

PubMed

The excitability of hindlimb extensor and flexor motoneurons is tonically modulated by animal tilt and a large visual stimulus rotating about the animal's line of sight. This direction-specific modulation is opposite for extensor and flexor motoneurons and opposite for optokinetic and vestibular stimuli, thus combining to a functionally significant pattern of postural reflexes. PMID:304014

Thoden, U; Dichgans, J; Savidis, T

1977-10-24

410

Direction-specific optokinetic modulation of monosynaptic hind limb reflexes in cats  

Microsoft Academic Search

The excitability of hindlimb extensor and flexor motoneurons is tonically modulated by animal tilt and a large visual stimulus rotating about the animal's line of sight. This direction-specific modulation is opposite for extensor and flexor motoneurons and opposite for optokinetic and vestibular stimuli, thus combining to a functionally significant pattern of postural reflexes.

U. Thoden; J. Dichgans; Th. Savidis

1977-01-01

411

The effects of exercise and training on human cardiovascular reflex control  

Microsoft Academic Search

During physical activity, there is a graded withdrawal of vagal cardiac tone and a graded increase in sympathetic cardiac and vasomotor tone, initiated through both central command from the somatic motor cortex and muscle chemoreceptive and mechanoreceptive inputs. In parallel, there is an upward resetting of the operating point of the arterial baroreflex, with preserved reflex sensitivity. In contrast to

Saoirse E O’Sullivan; Christopher Bell

2000-01-01

412

Bernard J. Baars I.P. Pavlov and the Freedom Reflex  

E-print Network

in San Diego. PICTURE OF PAVLOV TO BE SUPPLIED #12;Abstract: Why was Ivan Pavlevich Pavlov so widelyBernard J. Baars I.P. Pavlov and the Freedom Reflex We started off with a very simple experiment not remain quiet when it was constrained in the stand. I.P. Pavlov (1927, Vol. I, Ch. XXVIII) If `A

Memphis, University of

413

Reflexive orienting in response to short- and long-duration gaze cues in young, young-old, and old-old adults.  

PubMed

Shifting visual focus on the basis of the perceived gaze direction of another person is one form of joint attention. In the present study, we investigated whether this socially relevant form of orienting is reflexive and whether it is influenced by age. Green and Woldorff (Cognition 122:96-101, 2012) argued that rapid cueing effects (i.e., faster responses to validly than to invalidly cued targets) were limited to conditions in which a cue overlapped in time with a target. They attributed slower responses following invalid cues to the time needed to resolve the incongruent spatial information provided by the concurrently presented cue and target. In the present study, we examined the orienting responses of young (18-31 years), young-old (60-74 years), and old-old (75-91 years) adults following uninformative central gaze cues that overlapped in time with the target (Exp. 1) or that were removed prior to target presentation (Exp. 2). When the cue and target overlapped, all three groups localized validly cued targets more quickly than invalidly cued targets, and validity effects emerged earlier for the two younger groups (at 100 ms post-cue-onset) than for the old-old group (at 300 ms post-cue-onset). With a short-duration cue (Exp. 2), validity effects developed rapidly (by 100 ms) for all three groups, suggesting that validity effects resulted from reflexive orienting based on the gaze cue information rather than from cue-target conflict. Thus, although old-old adults may be slow to disengage from persistent gaze cues, attention continues to be reflexively guided by gaze cues late in life. PMID:24170377

Gayzur, Nora D; Langley, Linda K; Kelland, Chris; Wyman, Sara V; Saville, Alyson L; Ciernia, Annie T; Padmanabhan, Ganesh

2014-02-01

414

A- and C-reflexes elicited in cardiac sympathetic nerves by single shock to a somatic afferent nerve include spinal and supraspinal components in anesthetized rats.  

PubMed

The spinal and supraspinal components of both A- and C-reflexes were studied in the somato-cardiac sympathetic reflex discharges elicited by a single electrical shock either to a spinal (T3-4) afferent nerve or to a limb (tibial) afferent nerve in urethane anesthetized rats. In central nervous system (CNS) intact rats, a single shock to a T3-4 spinal afferent nerve produced early and late A-reflex discharges with latencies of 20 +/- 1 ms and 62 +/- 6 ms, respectively, and a C-reflex with a latency of 136 +/- 9 ms in a cardiac sympathetic efferent nerve. After spinalization at the first cervical level, stimulation of the same spinal afferent nerve produced an A-reflex with the same latency as the early A-reflex in CNS-intact rats and a C-reflex with a latency of 86 +/- 3 ms. The amplitude of the early A-reflex became augmented after spinal transection. On the other hand, a single shock to a tibial afferent nerve evoked an A-reflex discharge with a latency of 41 +/- 2 ms and a C-reflex discharge with a latency of 210 +/- 13 ms in CNS-intact rats. These A- and C-reflexes elicited by stimulation of a tibial afferent nerve were not observed after spinalization. It was concluded that cardiac sympathetic A- and C-reflex discharges evoked by stimulation of a segmental spinal afferent nerve in CNS-intact rats are of spinal and supraspinal origin, and those evoked by tibial nerve stimulation are of supraspinal origin. The spinal reflex pathway is segmentally organized, because the spinal reflex is evoked only when stimulation is delivered to afferent nerves close to the cardiac sympathetic outflow segments. With the CNS intact, the spinal reflex component is depressed by descending inhibitory pathways originating in the brain. PMID:8808803

Kimura, A; Sato, A; Sato, Y; Suzuki, H

1996-05-01

415

Oral sapropterin augments reflex vasoconstriction in aged human skin through noradrenergic mechanisms  

PubMed Central

Reflex vasoconstriction is attenuated in aged skin due to a functional loss of adrenergic vasoconstriction. Bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for catecholamine synthesis, is reduced with aging. Locally administered BH4 increases vasoconstriction through adrenergic mechanisms in aged human skin. We hypothesized that oral sapropterin (Kuvan, a pharmaceutical BH4) would augment vasoconstriction elicited by whole-body cooling and tyramine perfusion in aged skin. Ten healthy subjects (age 75 ± 2 yr) ingested sapropterin (10 mg/kg) or placebo in a randomized, double-blind crossover design. Venous blood samples were collected prior to, and 3 h following ingestion. Three intradermal microdialysis fibers were placed in the forearm skin for local delivery of 1) lactated Ringer, 2) 5 mM BH4, and 3) 5 mM yohimbine + 1 mM propranolol (Y+P; to inhibit adrenergic vasoconstriction). Red cell flux was measured at each site by laser-Doppler flowmetry (LDF) as reflex vasoconstriction was induced by lowering and then clamping whole-body skin temperature (T?sk) using a water-perfused suit. Following whole-body cooling, subjects were rewarmed and 1 mM tyramine was perfused at each site to elicit endogenous norepinephrine release from the perivascular nerve terminal. Cutaneous vascular conductance was calculated as CVC = LDF/mean arterial pressure and expressed as change from baseline (?CVC). Plasma BH4 was elevated 3 h after ingestion of sapropterin (43.8 ± 3 vs. 19.1 ± 2 pmol/ml; P < 0.001). Sapropterin increased reflex vasoconstriction at the Ringer site at T?sk ? 32.5°C (P < 0.05). Local BH4 perfusion augmented reflex vasoconstriction at T?sk ? 31.5°C with placebo treatment only (P < 0.05). There was no treatment effect on reflex vasoconstriction at the BH4-perfused or Y+P-perfused sites. Sapropterin increased pharmacologically induced vasoconstriction at the Ringer site (?0.19 ± 0.03 vs. ?0.08 ± 0.02 ?CVC; P = 0.01). There was no difference in pharmacologically induced vasoconstriction between treatments at the BH4-perfused site (?0.16 ± 0.04 vs. ?0.14 ± 0.03 ?CVC; P = 0.60) or the Y+P-perfused site (?0.05 ± 0.02 vs.?0.06 ± 0.02 ?CVC; P = 0.79). Sapropterin increases both reflex (cold-induced) and pharmacologically induced vasoconstriction through adrenergic mechanisms and may be a viable intervention to improve reflex vasoconstriction in aged humans. PMID:23869061

Stanhewicz, Anna E.; Kenney, W. Larry

2013-01-01

416

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

PubMed Central

Here, we review the angular vestibulocollic reflex (VCR) focusing on its function during unexpected and voluntary head movements. Theoretically, the VCR could (1) stabilize the head in space during body movements and/or (2) dampen head oscillations that could occur as a result of the head’s underdamped mechanics. The reflex appears unaffected when the simplest, trisynaptic VCR pathways are severed. The VCR’s efficacy varies across species; in humans and monkeys, head stabilization is ineffective during low-frequency body movements in the yaw plan. While the appearance of head oscillations after the attenuation of semicircular canal function suggests a role in damping, this interpretation is complicated by defects in the vestibular input to other descending motor pathways such as gaze premotor circuits. Since the VCR should oppose head movements, it has been proposed that the reflex is suppressed during voluntary head motion. Consistent with this idea, vestibular-only (VO) neurons, which are possible vestibulocollic neurons, respond vigorously to passive, but not active, head rotations. Although VO neurons project to the spinal cord, their contribution to the VCR remains to be established. VCR cancelation during active head movements could be accomplished by an efference copy signal negating afferent activity related to active motion. Oscillations occurring during active motion could be eliminated by some combination of reflex actions and voluntary motor commands that take into account the head’s biomechanics. A direct demonstration of the status of the VCR during active head movements is required to clarify the function of the reflex. PMID:21442224

Cullen, Kathleen E.

2013-01-01

417

Spatial patterns of reflex evoked by pressure stimulation of the foot pads in cats.  

PubMed Central

1. The spatial patterns of reflexes elicited by localized pressure stimulation of the foot skin were analysed by recording electromyographic activities of various hindlimb muscles or muscle nerve discharges in cats anaesthetized with sodium pentobarbitone. 2. Reflex discharges evoked by stimulation of the central pad occurred mainly in physiological toe extensors located in the foot. Stimulus-response relationships of single motor units revealed characteristically wide ranges of graded response and recruitment. 3. Within the central pad, the strongest excitation was evoked from the central lobe and was distributed to extensors of all four toes. Excitation from the medial and the lateral lobes was usually asymmetrical and weaker in toe muscles of the stimulated side. It is suggested that the weakness was in part due to concomitant inhibition. 4. Stimulation of a toe pad caused marked suppression of central pad-evoked activity of toe extensors with a highly specific spatial pattern. The inhibition was strongest in extensors of its own toe, and gradually weaker in the more distant toes. Weak excitation was occasionally evoked in extensors of the most medial or lateral toes, when the most lateral or the most medial toe-pad, respectively, was stimulated. 5. A similar pattern of relfex to that from the toe pad was evoked from the claw base and the hairy toe dorsum of each digit. 6. Reflex effects, both inhibitory and excitatory, from the central and toe pads, claw bases and toe dorsum were maintained during prolonged stimuli, indicating that slowly adapting receptors contributed to these reflexes. 7. It is concluded that stimulation of localized skin areas of the foot, particularly the pads, evokes highly specialized reflexes, which may be important in controlling movements of individual digits. Images Fig. 1 PMID:2324993

Hongo, T; Kudo, N; Oguni, E; Yoshida, K

1990-01-01

418

Effect of Aging on Hypopharyngeal Safe Volume and the Aerodigestive Reflexes Protecting the Airways  

PubMed Central

Objectives/Hypothesis Studies on young volunteers have shown that aerodigestive reflexes are triggered before the maximum volume of fluid that can safely collect in the hypopharynx before spilling into the larynx is exceeded (hypopharyngeal safe volume [HPSV]). The objective of this study was to determine the influence of aging on HPSV and pharyngoglottal closure reflex (PGCR), pharyngo-UES contractile reflex (PUCR), and reflexive pharyngeal swallow (RPS). Study Design Comparison between two groups of different age ranges. Methods Ten young (25 ±3 standard deviation [SD] years) and 10 elderly (77 ±3 SD years) subjects were studied. PGCR, PUCR, and RPS were elicited by perfusing water into the pharynx rapidly and slowly. HPSV was determined by abolishing RPS with pharyngeal anesthesia. Results Frequency–elicitation of PGCR and PUCR were significantly lower in the elderly compared to the young during slow water perfusion (47% vs. 97% and 40% vs. 90%, respectively, P <.001). RPS was absent in five of the 30 (17%) slow injections in the elderly group. In these elderly subjects, HPSV was exceeded and laryngeal penetration of the water was seen. The threshold volume to elicit PGCR, PUCR, and RPS was significantly lower than the HPSV during rapid injections. Except for RPS, these volumes were also significantly lower than HPSV during slow injections. Conclusions PGCR, PUCR, and RPS reflexes are triggered at a threshold volume significantly lower than the HPSV in both young and elderly subjects. Lower frequency–elicitation of PGCR, PUCR, and RPS in the elderly can predispose them to the risks of aspiration. PMID:24281906

Dua, Kulwinder S.; Surapaneni, Sri Naveen; Kuribayashi, Shiko; Hafeezullah, Mohammed; Shaker, Reza

2014-01-01

419

Basic Concepts in Understanding Recovery of Function in Vestibular Reflex Networks during Vestibular Compensation  

PubMed Central

Unilateral peripheral vestibular lesions produce a syndrome of oculomotor and postural deficits with the symptoms at rest, the static symptoms, partially or completely normalizing shortly after the lesion due to a process known as vestibular compensation. The symptoms are thought to result from changes in the activity of vestibular sensorimotor reflexes. Since the vestibular nuclei must be intact for recovery to occur, many investigations have focused on studying these neurons after lesions. At present, the neuronal plasticity underlying early recovery from the static symptoms is not fully understood. Here we propose that knowledge of the reflex identity and input–output connections of the recorded neurons is essential to link the responses to animal behavior. We further propose that the cellular mechanisms underlying vestibular compensation can be sorted out by characterizing the synaptic responses and time course for change in morphologically defined subsets of vestibular reflex projection neurons. Accordingly, this review focuses on the perspective gained by performing electrophysiological and immunolabeling studies on a specific subset of morphologically defined, glutamatergic vestibular reflex projection neurons, the principal cells of the chick tangential nucleus. Reference is made to pertinent findings from other studies on vestibular nuclei neurons, but no comprehensive review of the literature is intended since broad reviews already exist. From recording excitatory and inhibitory spontaneous synaptic activity in principal cells, we find that the rebalancing of excitatory synaptic drive bilaterally is essential for vestibular compensation to proceed. This work is important for it defines for the first time the excitatory and inhibitory nature of the changing synaptic inputs and the time course for changes in a morphologically defined subset of vestibular reflex projection neurons during early stages of vestibular compensation. PMID:22363316

Peusner, Kenna D.; Shao, Mei; Reddaway, Rebecca; Hirsch, June C.

2012-01-01

420

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

PubMed

Fipronil (FPN) is a phenylpyrazole insecticide used in veterinary services and agriculture, and it is of considerable concern to public health. It inhibits the chloride channels associated with gamma-amino butyric acid (GABA) receptors in mammals and also inhibits the chloride channels associated with GABA and glutamate (Glu) receptors in insects. In this study, a commercial product containing fipronil was orally administered to pregnant Wistar rats at dose levels of 0.1, 1.0, or 10.0mg/kg/day from the sixth to twentieth day of gestation (n=10 pregnant rats/group). Its toxicity was evaluated based on maternal toxicity, reproductive quality, maternal behavior, and offspring physical as well as reflex development. All parameters observed in the observed offspring were assigned to one ink-marked couple in each litter (n=20 animals/group - 10 males and 10 females). The offspring couple represented the litter. Slight maternal toxicity presented during the second week of gestation for each fipronil dose and during the third gestational week at the highest dose due to lower chow intake. However, no effects were observed for gestational weight gain or gestation time, and the reproductive quality was not impaired, which suggests no adverse maternal effects from the doses during pregnancy. Moreover, the lowest fipronil dose compromised the active and reflexive maternal responses, but the highest dose induced a stereotyped active response without interfering in the reflexive reaction. For offspring development, no differences in physical growth parameters were observed between the groups. However, considering reflex development, our results showed that negative geotaxis reflex development was delayed in the offspring at the lowest fipronil dose, and palmar grasp was lost earlier at the lowest and intermediate fipronil doses. These results suggest that the alterations observed herein may be due to either the GABAergic system or endocrine disruption, considering that fipronil also acts as an endocrine disruptor. PMID:24978116

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

2014-01-01

421

Environmental Conditions Environmental Conditions  

E-print Network

Environmental Conditions Environmental Conditions Appendix II The unique geology, hydrology and instream habitat. This chapter examines how environmental conditions in the Deschutes watershed affect, the discussion characterizes the environmental conditions within three watershed areas: the Lower Deschutes

422

Phase-dependent and task-dependent modulation of stretch reflexes during rhythmical hand tasks in humans  

PubMed Central

Phase-dependent and task-dependent modulation of reflexes has been extensively demonstrated in leg muscles during locomotory activity. In contrast, the modulation of reflex responses of hand muscles during rhythmic movement is poorly documented. The objective of this study was to determine whether comparable reflex modulation occurs in muscles controlling finger motions during rhythmic, fine-motor tasks akin to handwriting. Twelve healthy subjects performed two rhythmic tasks while reflexes were evoked by mechanical perturbations applied at various phases of each task. Electromyograms (EMGs) were recorded from four hand muscles, and reflexes were averaged during each task relative to the movement phase. Stretch reflexes in all four muscles were found to be modulated in amplitude with respect to the phase of the rhythmic tasks, and also to vary distinctly with the tasks being conducted. The extent and pattern of reflex modulation differed between muscles in the same task, and between tasks for the same muscle. Muscles with a primary role in each task showed a higher correlation between reflex response and background EMG than other muscles. The results suggest that the modulation patterns observed may reflect optimal strategies of central–peripheral interactions in controlling the performance of fine-motor tasks. As with comparable studies on locomotion, the phase-dependency of the stretch reflexes implies a dynamically fluctuating role of proprioceptive feedback in the control of the hand muscles. The clear task-dependency is also consistent with a dynamic interaction of sensory feedback and central programming, presumably adapted to facilitate the successful performance of the different fine-motor tasks. PMID:15746170

Xia, Ruiping; Bush, Brian M H; Karst, Gregory M

2005-01-01

423

The inhibitory role of nitric oxide (NO) in the somatocardiac sympathetic C-reflex in anesthetized rats.  

PubMed

The role of nitric oxide (NO) in the two somatosympathetic reflex arcs, i.e. A- and C-reflexes, was examined using NO synthase (NOS) inhibitor in anesthetized rats. The A- and C-reflex components were recorded from a cardiac sympathetic efferent nerve and elicited by stimulation of myelinated A and unmyelinated C afferent fibers in the left tibial nerve. NG-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, when administered by either intrathecal (i.t.) or into the cisterna magna (i.c.m.) routes, augmented only the C-reflex in a dose-dependent manner. The effective i.t. dose of L-NAME to augment the C-reflex was approximately 1000 times the i.c.m. dose. NG-nitro-D-arginine methyl ester (D-NAME), an isomer of L-NAME, had no effect on either A- or C-reflexes, when administered i.c.m. Neither i.c.m. pre-treatment nor post-treatment with L-arginine, a NOS substrate, influenced either A- or C-reflexes, but i.c.m. pre-treatment with L-arginine abolished the facilitatory effect of L-NAME on the C-reflex. These results suggest that NO, synthesized in the brain stem, plays an inhibitory role in the central modulation of the somatocardiac sympathetic C-reflex. The possibility of movement of L-NAME to the brain stem from the spinal cord is discussed. PMID:7478302

Li, W M; Sato, A; Suzuki, A

1995-07-01

424

Adaptive changes of the locomotor pattern and cutaneous reflexes during locomotion studied in the same cats before and after spinalization  

PubMed Central

Descending supraspinal inputs exert powerful influences on spinal reflex pathways in the legs. Removing these inputs by completely transecting the spinal cord changes the state (i.e. the configuration of the spinal circuitry) of the locomotor network and undoubtedly generates a reorganization of reflex pathways. To study changes in reflex pathways after a complete spinalization, we recorded spinal reflexes during locomotion before and after a complete transection of the spinal cord at the 13th thoracic segment in cats. We chronically implanted electrodes in three cats, to record electromyography (EMG) in several hindlimb muscles and around the left tibial (Tib) nerve at the ankle to elicit reflexes during locomotion before and after spinalization in the same cat. Control values of kinematics, EMGs and reflexes were obtained during intact locomotion for 33–60 days before spinalization. After spinalization, cats were trained 3–5 times a week on a motorized treadmill. Recordings resumed once a stable spinal locomotion was achieved (26–43 days), with consistent plantar foot placement and full hindquarter weight support without perineal stimulation. Changes in Tib nerve reflex responses after spinalization in the same cat during locomotion were found in all muscles studied and were often confined to specific phases of the step cycle. The most remarkable change was the appearance of short-latency excitatory responses in some ipsilateral ankle extensors during stance. Short-latency excitatory responses in the ipsilateral tibialis anterior were increased during stance, whereas in other flexors such as semitendinosus and sartorius, increases were mostly confined to swing. Longer-latency excitatory responses in ipsilateral flexors were absent or reduced. Responses evoked in limb muscles contralateral to stimulation were generally increased throughout the step cycle. These reflex changes after spinalization provide important clues regarding the functional reorganization of reflex pathways during spinal locomotion. PMID:18420704

Frigon, Alain; Rossignol, Serge

2008-01-01

425

Conditioning honeybees to discriminate between heritable odors from full and half sisters  

Microsoft Academic Search

Differential conditioning of the proboscis extension reflex in honeybees is used to assess whether worker honeybees can be trained to discriminate between volatile odors emanating from different kin groups consisting of 2 or 20 workers. These odor source group workers are all reared and maintained under identical environmental conditions. They are the progeny of a queen that has been instrumentally

Wayne M. Getz; Dorothea Brfickner; Katherine B. Smith

1986-01-01

426

Parasympathetic Control of Airway Submucosal Glands: Central Reflexes and the Airway Intrinsic Nervous System  

PubMed Central

Airway submucosal glands produce the mucus that lines the upper airways to protect them against insults. This review summarizes evidence for two forms of gland secretion, and hypothesizes that each is mediated by different but partially overlapping neural pathways. Airway innate defense comprises low level gland secretion, mucociliary clearance and surveillance by airway-resident phagocytes to keep the airways sterile in spite of nearly continuous inhalation of low levels of pathogens. Gland secretion serving innate defense is hypothesized to be under the control of intrinsic (peripheral) airway neurons and local reflexes, and these may depend disproportionately on non-cholinergic mechanisms, with most secretion being produced by VIP and tachykinins. In the genetic disease cystic fibrosis, airway glands no longer secrete in response to VIP alone and fail to show the synergy between VIP, tachykinins and ACh that is observed in normal glands. The consequent crippling of the submucosal gland contribution to innate defense may be one reason that cystic fibrosis airways are infected by mucus-resident bacteria and fungi that are routinely cleared from normal airways. By contrast, the acute (emergency) airway defense reflex is centrally mediated by vagal pathways, is primarily cholinergic, and stimulates copious volumes of gland mucus in response to acute, intense challenges to the airways, such as those produced by very vigorous exercise or aspiration of foreign material. In cystic fibrosis, the acute airway defense reflex can still stimulate the glands to secrete large amounts of mucus, although its properties are altered. Importantly, treatments that recruit components of the acute reflex, such as inhalation of hypertonic saline, are beneficial in treating cystic fibrosis airway disease. The situation for recipients of lung transplants is the reverse; transplanted airways retain the airway intrinsic nervous system but lose centrally mediated reflexes. The consequences of this for gland secretion and airway defense are poorly understood, but it is possible that interventions to modify submucosal gland secretion in transplanted lungs might have therapeutic consequences. Introduction and overviewProtecting the Airways: mucus and submucosal glands.The airway intrinsic nervous system: a special role in innate defense?Innate defense: prophylactic secretion and local responses.Acute ‘Emergency’ airway defense reflexesAirway receptors: Improved methods reveal greater diversityHijacking emergency defense for innate defense: receptor plasticity and airways sen