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1

Conditional reflex theory and motivational behavior.  

PubMed

Motivational behavior is explained in the light of reflex theory by reference to: (i) Pavlov's concept of nerve center as an assembly of structures messing the same function, (ii) Sherrington's and Magnus' ideas about the hierarchical structure of the nervous system, (iii) author's notion about the multistage arc of the unconditioned reflex, i.e., an arc with many branches in its central path, each passing through the main integrative levels of the central nervous system, (iv) experimental facts of this laboratory and particularly concerning bidirectional conditioned connections. It is assumed that motivational behavior elicited by endogenous and exogenous factors through hereditary mechanisms may be regarded as a manifestation of complex inborn reflexes, in which the main branch is located in the limbic system. The cortical branch makes it possible to elaborate particular conditioned reflexes. Physiological mechanisms of so-called purposive movements in motivational behavior is regarded as the activity of backward conditioned connections, leading from the unconditioned reflex centers to the centers controlling motor effectors. PMID:4838073

Asratyan, E A

1974-01-01

2

Soleus H-Reflex Operant Conditioning Changes The H-Reflex Recruitment Curve  

PubMed Central

Introduction Operant conditioning can gradually change the human soleus H-reflex. The protocol conditions the reflex near M-wave threshold. This study examined its impact on the reflexes at other stimulus strengths. Methods H-reflex recruitment curves were obtained before and after a 24-session exposure to an up-conditioning (HRup) or down-conditioning (HRdown) protocol and were compared. Results In both HRup and HRdown subjects, conditioning affected the entire H-reflex recruitment curve. In 5 of 6 HRup and 3 of 6 HRdown subjects, conditioning elevated (HRup) or depressed (HRdown), respectively, the entire curve. In the other HRup subject or the other 3 HRdown subjects, the curve was shifted to the left or to the right, respectively. Discussion H-reflex conditioning does not simply change the H-reflex to a stimulus of particular strength; it also changes the H-reflexes to stimuli of different strengths. Thus, it is likely to affect many actions in which this pathway participates. PMID:23281107

Thompson, Aiko K.; Chen, Xiang Yang; Wolpaw, Jonathan R.

2012-01-01

3

[Electroencephalographic analysis of a conditioned reflex to time].  

PubMed

EEG parameters in different cortical territories of free moving dogs were analyzed during formation of conditioned reflex to time, in situation of instrumental alimentary conditioning. It was shown that in organization of a reflex to time as a complex reaction(present, trace and rhythmic processes), different brain systems play different roles in the formation of its stages. Sensory systems provide for the complex of trace processes underlying reaction to time. Associative structures are involved in the afferent synthesis necessary for the present moment. Integrative-triggering formations attach formed reaction to a strictly fixed time. PMID:7386013

Mukhin, E I

1980-01-01

4

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

5

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

PubMed Central

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

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

2010-01-01

6

The effect of early partial decortication on visual and auditory conditioned reflexes in chickens  

Microsoft Academic Search

Removal of the cerebral hemispheres, including the corpora striata, in young chicks has a marked effect on their subsequent conditioned reflex activity. The stability and regularity of the conditioned reflexes is reduced, and differentiation of the visual and of the auditory conditioned signals deteriorates. Removal of the rudimentary cortical areas in young chicks has little effect on their subsequent reflex

O. E. Panomareva; A. B. Kogan; V. N. Chernigovskii

1959-01-01

7

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

E-print Network

to spinal cord injury, cerebral palsy, stroke, amyotrophic lateral sclerosis (ALS), or other chronic the same circuits. Appropriate reflex conditioning can help to reduce locomotor abnormalities caused

Valero-Cuevas, Francisco

8

Acquisition of a conditioned reflex in New Zealand White rabbits from three sources  

Microsoft Academic Search

Summary In studies of learning using rabbits, there has been standardization of behavioural procedures across laboratories. Less attention has been paid to variation that may arise from genetic differences and\\/or differences in rearing conditions. The present experiment revealed that acquisition of a conditioned reflex can be affected dramatically by such differences. Specifically, the acquisition of a conditioned reflex in New

E. James Kehoe; Amanda J. Horne; Jennifer Kingham; Thomas Martin; Wayne Roach

1995-01-01

9

Persistent beneficial impact of H-reflex conditioning in spinal cord-injured rats.  

PubMed

Operant conditioning of a spinal cord reflex can improve locomotion in rats and humans with incomplete spinal cord injury. This study examined the persistence of its beneficial effects. In rats in which a right lateral column contusion injury had produced asymmetric locomotion, up-conditioning of the right soleus H-reflex eliminated the asymmetry while down-conditioning had no effect. After the 50-day conditioning period ended, the H-reflex was monitored for 100 [±9 (SD)] (range 79-108) more days and locomotion was then reevaluated. After conditioning ended in up-conditioned rats, the H-reflex continued to increase, and locomotion continued to improve. In down-conditioned rats, the H-reflex decrease gradually disappeared after conditioning ended, and locomotion at the end of data collection remained as impaired as it had been before and immediately after down-conditioning. The persistence (and further progression) of H-reflex increase but not H-reflex decrease in these spinal cord-injured rats is consistent with the fact that up-conditioning improved their locomotion while down-conditioning did not. That is, even after up-conditioning ended, the up-conditioned H-reflex pathway remained adaptive because it improved locomotion. The persistence and further enhancement of the locomotor improvement indicates that spinal reflex conditioning protocols might supplement current therapies and enhance neurorehabilitation. They may be especially useful when significant spinal cord regeneration becomes possible and precise methods for retraining the regenerated spinal cord are needed. PMID:25143542

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

2014-11-15

10

Exercise-induced neuromuscular dysfunction under reflex conditions  

Microsoft Academic Search

.   The purpose of this research was to describe further the effects of exercise-induced muscle damage on reflex sensitivity.\\u000a The subjects were eight physically active, but untrained males, between the ages of 18 and 29 years. The effects of eccentric\\u000a and concentric exercise on patellar tendon reflex responses were determined. The 8 week experiment consisted of two, 5 day,\\u000a test protocols with a

Thomas Kaufman; Jeanmarie R. Burke; Mark J. Davis; Larry J. Durstine

2001-01-01

11

Significance of reinforcement for differentiation of signals of instrumental conditional reflexes in rats  

Microsoft Academic Search

Conclusions  \\u000a \\u000a \\u000a \\u000a 1) \\u000a Elaboration of defensive instrumental conditioned reflexes proceeds much more readily than elaboration of analogous drinking\\u000a conditioned reflexes.\\u000a \\u000a \\u000a \\u000a 2) \\u000a Differentiation with defensive reinforcement is elaborated more readily than with drinking reinforcement; in the first case\\u000a it is done mainly owing to the increase of inhibition of the nonreinforced reflexes, in the second case, owing to the increase\\u000a of the

V. N. Semaguin; A. V. Zukhar

1983-01-01

12

A robot conditioned reflex system modeled after the cerebellum  

Microsoft Academic Search

Most modern theories of behavior involve a hierarchical structure whereby low level behavioral units are controlled or manipulated by higher centers so as to produce characteristic patterns of movement. In the simplest life forms, low level behavioral units may consist of simple reflex arcs with very little higher level control. In intermediate forms, the low level behavioral units may be

James S. Albus

1972-01-01

13

Electroencephalographic analysis of a conditioned reflex to time  

Microsoft Academic Search

Conclusions 1.During CRT formation fast spindle-like electrical activity with a frequency of 28–32 waves\\/sec is generated in the cortical projection (auditory, visual) and association (parietal) areas, and it is enhanced in the anterior zones of the brain (somatosensory and motor cortex).2.During the formation of a reflex to time close interconnection is observed (with respect to spatial synchronous activity of the

E. I. Mukhin

1982-01-01

14

OPERANT CONDITIONING OF A SPINAL REFLEX CAN IMPROVE LOCOMOTION AFTER SPINAL CORD INJURY IN HUMANS  

PubMed Central

Operant conditioning protocols can modify the activity of specific spinal cord pathways and can thereby affect behaviors that use these pathways. To explore the therapeutic application of these protocols, we studied the impact of down-conditioning the soleus H-reflex in people with impaired locomotion caused by chronic incomplete spinal cord injury. After a baseline period in which soleus H-reflex size was measured and locomotion was assessed, subjects completed either 30 H-reflex down-conditioning sessions (DC subjects) or 30 sessions in which the H-reflex was simply measured (Unconditioned (UC) subjects), and locomotion was reassessed. Over the 30 sessions, the soleus H-reflex decreased in two-thirds of the DC subjects (a success rate similar to that in normal subjects) and remained smaller several months later. In these subjects, locomotion became faster and more symmetrical, and the modulation of EMG activity across the step-cycle increased bilaterally. Furthermore, beginning about halfway through the conditioning sessions, all of these subjects commented spontaneously that they were walking faster and farther in their daily lives, and several noted less clonus, easier stepping, and/or other improvements. The H-reflex did not decrease in the other DC subjects or in any of the UC subjects; and their locomotion did not improve. These results suggest that reflex conditioning protocols can enhance recovery of function after incomplete spinal cord injuries and possibly in other disorders as well. Because they are able to target specific spinal pathways, these protocols could be designed to address each individual’s particular deficits, and might thereby complement other rehabilitation methods. PMID:23392666

Thompson, Aiko K.; Pomerantz, Ferne; Wolpaw, Jonathan R.

2013-01-01

15

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

16

The simplest motor skill: mechanisms and applications of reflex operant conditioning.  

PubMed

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

Thompson, Aiko K; Wolpaw, Jonathan R

2014-04-01

17

Functional changes of brainstem reflexes in Parkinson's disease conditioning of the blink reflex R2 component by paired and index finger stimulation  

Microsoft Academic Search

Summary Recovery curves of the R2 component of the blink reflex have been studied in 10 control subjects and 13 parkinsonian patients both after ipsilateral paired stimulation of the supraorbital nerve and after index finger stimulation. In control subjects, both types of conditioning induced a comparable marked inhibition lasting more than 600ms. In parkinsonian patients, inhibition was reduced after both

A. Lozza; J. L. Pepin; G. Rapisarda; A. Moglia; P. J. Delwaide

1997-01-01

18

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

ERIC Educational Resources Information Center

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

Wolpaw, Jonathan R.; Chen, Xiang Yang

2006-01-01

19

Operant conditioning of spinal reflexes: from basic science to clinical therapy  

PubMed Central

New appreciation of the adaptive capabilities of the nervous system, recent recognition that most spinal cord injuries are incomplete, and progress in enabling regeneration are generating growing interest in novel rehabilitation therapies. Here we review the 35-year evolution of one promising new approach, operant conditioning of spinal reflexes. This work began in the late 1970’s as basic science; its purpose was to develop and exploit a uniquely accessible model for studying the acquisition and maintenance of a simple behavior in the mammalian central nervous system (CNS). The model was developed first in monkeys and then in rats, mice, and humans. Studies with it showed that the ostensibly simple behavior (i.e., a larger or smaller reflex) rests on a complex hierarchy of brain and spinal cord plasticity; and current investigations are delineating this plasticity and its interactions with the plasticity that supports other behaviors. In the last decade, the possible therapeutic uses of reflex conditioning have come under study, first in rats and then in humans. The initial results are very exciting, and they are spurring further studies. At the same time, the original basic science purpose and the new clinical purpose are enabling and illuminating each other in unexpected ways. The long course and current state of this work illustrate the practical importance of basic research and the valuable synergy that can develop between basic science questions and clinical needs. PMID:24672441

Thompson, Aiko K.; Wolpaw, Jonathan R.

2014-01-01

20

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

21

Moro reflex  

MedlinePLUS

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

22

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...

23

Aversive Learning in Honeybees Revealed by the Olfactory Conditioning of the Sting Extension Reflex  

PubMed Central

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

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

2007-01-01

24

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

PubMed Central

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

Futagi, Yasuyuki; Toribe, Yasuhisa; Suzuki, Yasuhiro

2012-01-01

25

Comparison of the classically conditioned withdrawal reflex in cerebellar patients and healthy control subjects during stance: I. electrophysiological characteristics.  

PubMed

The aim of this study was to demonstrate the involvement of the human cerebellum in the classically conditioned lower limb withdrawal reflex in standing subjects. Electromyographic activity was recorded from the main muscle groups of both legs of eight patients with cerebellar disease (CBL) and eight control subjects (CTRL). The unconditioned stimulus (US) consisted of electrical stimulation of the tibial nerve at the medial malleolus. The conditioning stimulus (CS) was an auditory signal given via headphones. Experiments started with 70 paired conditioning stimulus-unconditioned stimulus(CSUS) trials followed by 50 US-alone trials. The general reaction consisted of lifting and flexing the stimulated (stepping) leg with accompanying activation of the contralateral (supporting) leg. In CTRL, the ipsilateral (side of stimulation) flexor and contralateral extensor muscles were activated characteristically. In CBL, the magnitudes of ipsilateral flexor and contralateral extensor muscle activation were reduced comparably. In CTRL, the conditioning process increased the incidence of conditioned responses (CR), following a typical learning curve, while CBL showed a clearly lower CR incidence with a marginal increase, albeit, at a shorter latency. Conditioning processes also modified temporal parameters by shortening unconditioned response (UR) onset latencies and UR times to peak and, more importantly in CBL, also the sequence of activation of muscles, which became similar to that of CTRL. The expression of this reflex in standing subjects showed characteristic differences in the groups tested with the underlying associative processes not being restricted exclusively to the CR but also modifying parameters of the innate UR. PMID:22836373

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

2013-02-01

26

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

Microsoft Academic Search

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

A. S. Denisova

1981-01-01

27

Effect of some drugs, experimental stress and estrus on unstable and fixed conditioned alimentary motor reflexes in cats. Meclophenoxate, chlorprothixen, caffeine, piracetam. Part VI.  

PubMed

A group of 10 cats, both sexes, were studied for the effect of peroral administration of the meclophenoxate (Cetrexin, Léciva, 1.5 mg kg-1) + chlorprothixen (Chlorprothixen, Spofa, 0.045 mg kg-1) + caffeine (Coffeinum natrium benzoicum, Spofa, 0.15 mg kg-1) combination upon the fixation of conditioned alimentary motor reflexes to a sound signal in the course of a 10-week experiment. The mentioned combination of drugs demonstrated a beneficial protective influence on the fixed alimentary motor reflexes against laboratory stress. The results were compared with the earlier fixation of the same reflexes in another group of 11 cats under piracetam (Nootropil, U.C.B. 20 mg kg-1, s.c.). In both groups of animals, the development of reflexes was performed in regular alterations of experiments under the effect of the drugs and control experiments. The drugs were administered 1 hour before the experiments. Both groups of animals showed significantly fewer intersignal and other incorrect motor reactions on the days they were given the drugs than the controls did. The number of fixed correct reactions and their latencies displayed only moderate insignificant differences between the pharmacological trials and the controls. The conclusions is that the actual development of conditioned alimentary motor reflexes was not found to be influenced by the action of the mentioned drugs modifying psychological functions and mental states. PMID:2149802

Medek, A; Stod?lka, J; Komenda, S

1990-01-01

28

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

Microsoft Academic Search

Background  Autonomous reflexes enable animals to respond quickly to potential threats, prevent injury and mediate fight or flight responses.\\u000a Intense acoustic stimuli with sudden onsets elicit a startle reflex while stimuli of similar intensity but with longer rise\\u000a times only cause a cardiac defence response. In laboratory settings, habituation appears to affect all of these reflexes so\\u000a that the response amplitude

Thomas Götz; Vincent M Janik

2011-01-01

29

Comparison of trunk muscle reflex activation patterns between active and passive trunk flexion-extension loading conditions.  

PubMed

The aim of the present study was to determine the effects of trunk flexion-extension loading on the neuromuscular reflexive latencies and amplitude responses of the trunk musculature. Eighteen male and female subjects (18-27yrs) participated in active and passive trunk flexion extension, performed ?7days apart. Subjects performed 60 trunk flexion-extension repetitions. Surface electromyography (EMG) was collected bilaterally from paraspinal and abdominal muscles. In the active condition, subjects volitionally moved their trunks, while in the passive condition the dynamometer controlled the movements. The trunk was perturbed before and immediately after 30 repetitions. Latency of muscle onset, latency of first peak, latency of maximum peak, and peak EMG amplitude were evaluated. No differences between conditions, sides, or perturbation session were apparent. Overall latencies were shorter in females (p<.05) and abdominal muscles compared to paraspinals (p<.05). Thoracic paraspinal muscle amplitudes were greater than all other muscles (p<.05). Based upon the present results, the neuromuscular system engages trunk flexor muscles prior to the paraspinals in order to provide possible stabilization of the trunk when flexor moments are generated. Overall, the results indicate no difference in response of the neuromuscular system to active or passive repetitive loading. PMID:24690742

Olson, Michael W

2014-04-01

30

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

31

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

32

Is the conditioned pain modulation paradigm reliable? A test-retest assessment using the nociceptive withdrawal reflex.  

PubMed

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

33

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, Jose A.; Fritsche, Raphael; Vuilleumier, Pascal H.; Oehler, Carmen; M?rch, Carsten D.; Arendt-Nielsen, Lars; Andersen, Ole K.; Curatolo, Michele

2014-01-01

34

Amygdalar NMDA Receptors Control the Expression of Associative Reflex Facilitation and Three Other Conditional Responses  

Microsoft Academic Search

Four conditional responses (CRs) were measured in rats implanted with bilateral cannulas in the basolateral nuclear complex of the amygdala (BLA). During retention testing in either the original training context or a shifted context, BLA was infused with artificial cerebral spinal fluid (ACSF) or ACSF containing an N-methyl-D-aspartate receptor antagonist (APV). Regardless of the testing context, APV infusion into BLA

Derick H. Lindquist; Thomas H. Brown

2004-01-01

35

Electrophysiological analysis of the conditioned reflex activity of cats during thirst  

Microsoft Academic Search

The EEG of the cerebral cortex and the electrohypothalamogram (EHG) was recorded in cats with a salt load and water deprivation during the performance of runs conditioned to non-salty and salty food signals. The non-salty food signal against the background of thirst was accompanied only by the activation of the cerebral cortex, whereas the hypothalamus in addition to the cortex

A. S. Batuev; B. G. Gafurov

1990-01-01

36

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

ERIC Educational Resources Information Center

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

Chen, Xiang Yang; Wolpaw, Jonathan R.

2005-01-01

37

Classical Conditioning and Conditioning-Specific Reflex Modification of Rabbit Heart Rate as a Function of Unconditioned Stimulus Location  

Microsoft Academic Search

Heart rate conditioning is used as an index of conditioned fear and is important for understanding disorders of anxiety and stress, including post traumatic stress disorder (PTSD). One important feature of PTSD is that patients generalize conditioned fear from danger signals to safety signals especially when the two signals have overlapping features. What has not been determined is whether generalization

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

2011-01-01

38

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

39

Chinese Reflexive Ziji: Syntactic Reflexes vs. Nonsyntactic Reflexes.  

ERIC Educational Resources Information Center

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

Pollard, Carl; Xue, Ping

1998-01-01

40

Reflexives in Mohawk  

E-print Network

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

Bonvillain, Nancy

1994-01-01

41

Embodied Self-Reflexivity  

ERIC Educational Resources Information Center

Drawing on G. H. Mead and Merleau-Ponty, this paper aims to extend our understanding of self-reflexivity beyond the notion of a discursive, abstract, and symbolic process. It offers a framework for embodied self-reflexivity, which anchors the self in the reflexive capacity of bodily sensations. The data consist of two years of ethnographic…

Pagis, Michal

2009-01-01

42

Instructions and the orienting reflex in semantic conditioning of the galvanic skin response in an innocuous situation  

Microsoft Academic Search

Used a modified semantic conditioning situation employing a reaction time (RT) paradigm to study the acquisition of differential GSRs in 105 college students. During acquisition, which was preceded by habituation, a repeated critical word (CW) was interspersed among filler words (FWs). A tone-signaled RT task occurred 10 sec after each presentation of the CW. Instructed groups were informed concerning all

Mary Pendery; Irving Maltzman

1977-01-01

43

Emotionally Colorful Reflexive Games  

E-print Network

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

Tarasenko, Sergey

2011-01-01

44

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,

45

Modernization and relational reflexivity  

Microsoft Academic Search

This paper deals with the issue of reflexivity in the different spheres of society, affected by the processes of globalization. The author argues that each sub-system of society is more or less differentiating itself according to a (prevailing) code or register of reflexivity. Global contextualism changes the way people manage the distinction between the particular and the universal (i.e. their

Pierpaolo Donati

2011-01-01

46

Epidemiology of reflex syncope  

E-print Network

? Abstract Cost-effective diagnostic approaches to reflex syncope require knowledge of its frequency and causes in different age groups. For this purpose we reviewed the available literature dealing with the epidemiology of reflex syncope. The incidence pattern of reflex syncope in the general population and general practice is bimodal with peaks in teenagers and in the elderly. In the young almost all cases of transient loss of consciousness are due to reflex syncope. The life-time cumulative incidence in young females ( ? 50 %) is about twice as high as in males ( ? 25 %). In the elderly, cardiac causes, orthostatic and postprandial hypotension, and the effects of medications are common, whereas typical vasovagal syncope is less frequent. In emergency departments, cardiac causes and orthostatic hypotension are more frequent especially in elderly subjects. Reflex syncope, however, remains the most common cause of syncope, but all-cause mortality in subjects with reflex syncope is not higher than in the general population. This knowledge about the epidemiology of reflex syncope can serve as a benchmark to develop cost-effective diagnostic approaches. ? Key words reflex syncope · epidemiology · incidence · prevalence · setting · prognosis

N. Colman; K. Nahm; K. S. Ganzeboom; W. K. Shen; J. B. Reitsma; M. Linzer; W. Wieling; H. Kaufmann; W. Wieling; N. Colman; K. Nahm; H. Kaufmann; W. K. Shen; J. B. Reitsma; M. Linzer

47

Totally reflexive extensions and modules  

E-print Network

We introduce the notion of totally reflexive extension of rings. It unifies Gorenstein orders and Frobenius extensions. We prove that for a totally reflexive extension, a module over the extension ring is totally reflexive if and only if its underlying module over the base ring is totally reflexive.

Chen, Xiao-Wu

2012-01-01

48

From Reflexive to Passive  

E-print Network

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

Sohn, Joong-Sun

1998-01-01

49

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

50

Dynamic properties of stretch reflex  

Microsoft Academic Search

Dynamic aspects of stretch and unloading reflexes were investigated in the hindlimb extensor muscles of decerebrate cats. A complex transformation of non-linear effects inherent in the dynamics of the deafferented muscle was seen to occur under reflex control without hysteris (underlying non-linear static qualities of the muscle) being suppressed. Hysteresis of stretch reflex is responsible for uncertainty in muscle length

A. I. Kostyukov

1989-01-01

51

The Babinski reflex  

Microsoft Academic Search

The plantar response is a reflex that involves not only the toes, but all muscles that shorten the leg. In the newborn the synergy is brisk, involving all flexor muscles of the leg; these include the toe 'extensors', which also shorten the leg on contraction and therefore are flexors in a physiological sense. As the nervous system matures and the

J. van Gijn

1995-01-01

52

Reflexivity in Pigeons  

ERIC Educational Resources Information Center

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…

Sweeney, Mary M.; Urcuioli, Peter J.

2010-01-01

53

The inflammatory reflex  

Microsoft Academic Search

Inflammation is a local, protective response to microbial invasion or injury. It must be fine-tuned and regulated precisely, because deficiencies or excesses of the inflammatory response cause morbidity and shorten lifespan. The discovery that cholinergic neurons inhibit acute inflammation has qualitatively expanded our understanding of how the nervous system modulates immune responses. The nervous system reflexively regulates the inflammatory response

Kevin J. Tracey

2002-01-01

54

Reflex secretion of the human parotid gland  

Microsoft Academic Search

Investigated the conditions which influence the secretion of the parotid gland directly or indirectly. A series of experiments were conducted, in which the secretion was recorded by counting the drops as they fell from the drainage tube. Eight Ss between 8 to 38 yrs of age were involved. Concludes that direct reflexes of the parotid gland were excited by the

K. S. Lashley

1916-01-01

55

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

56

Spinal reflexes in brain death.  

PubMed

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

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

2014-12-01

57

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

58

The acoustic reflex and temporary threshold shift: temporal characteristics.  

PubMed

One ear of each of seven normal-hearing subjects was exposed to a continuous 1000-Hz tone at 110 dB SPL for three minutes. During exposure, a broad-band noise at 100 dB SPL was presented to the contralateral ear. The noise was either continuous or pulsed. Four pulsed conditions employed repetition periods of 360, 180, 90, or 9 msec with a 50% duty cycle. A control condition in which no noise was presented was also included. Temporary threshold shift was measured at selected postexposure times at the frequency one-half octave above the exposure frequency. TTS2 was greatest for the control condition and least for the 360- and 180-msec conditions. Results are discussed in relation to the dynamics of the acoustic reflex, particularly reflex relaxation, reflex adaptation, and reflex temporal summation. PMID:904317

Karlovich, R S; Osier, H A; Gutnick, H N; Ivey, R G; Wolf, K; Schwimmer, S; Strennen, M L; Gerber, J

1977-09-01

59

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.

Macleish, Marlene Y.; Mclean, Bernice R.

2012-06-26

60

Reflexive functors of modules in Commutative Algebra  

E-print Network

Reflexive functors of modules are ubiquitous in Algebraic Geometry, mainly in the theory of linear representations of group schemes, and in "duality theories". In this paper we study and determine reflexive functors and we give many properties of reflexive functors.

Navarro, J; Sancho, P

2012-01-01

61

Reflexive and Reciprocal Elements in Ixil  

E-print Network

Reflexives and reciprocals in Ixil, a Mayan language of Guatemala, appear to have features which distinguish them from reflexives surveyed in typological studies such as Faltz 1985 and Geniusiene 1987. Third person reflexives and reciprocals seem...

Ayres, Glenn

1990-01-01

62

Patterning of somatosympathetic reflexes  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

63

Reflexive Monte-Carlo Search  

Microsoft Academic Search

Reflexive Monte-Carlo search uses the Monte-Carlo search of a given level to improve the search of the upper level. We describe the application to Morpion Solitaire. For the non touching version, reflexive M onte-Carlo search breaks the current record and establishes a new record of 78 moves.

Tristan Cazenave

64

From bioprospecting to reflexive governance  

Microsoft Academic Search

In this paper I evaluate the contribution of new institutional economics to reflexive governance in the field of bioprospecting. My hypothesis is that the design of governance arrangements that are both efficient and legitimate necessitates taking into account the reflexivity of the actors on the proposed institutional design. In considering this hypothesis, I apply current theoretical insights from new institutional

Tom Dedeurwaerdere

2005-01-01

65

Changes of compensatory proprioceptive evoked reflexes during hypoxia  

NASA Technical Reports Server (NTRS)

The ocular and third eyelid muscles of rabbits were the subjects of the investigation. 68 rabbits were tested in a pressure chamber at an altitude of up to 11,000 meters for 1 to 58 minutes. It was found that the evoked reflexes were highly resistant to hypoxically caused changes; restoration of altered reflexes occurred. Hypoxic ocular nystagmus was registered in high altitude conditions.

Komendantov, G. L.

1973-01-01

66

[A method for recording the human periodontal muscular reflex].  

PubMed

Principal block-diagram and characteristics of devices recording the parameters of periodontal muscular reflex in humans are presented. Twenty healthy volunteers aged 20 to 30 years with full dentition and normal occlusion and temporomandibular articulations unchanged were studied. Parameters of periodontal muscular reflex showed no bilateral asymmetry. Temporal muscles displayed 15 +/- 0.87 s latencies, masseters 13 +/- 0.8 latencies. Silent periods in temporal muscles were 22 +/- 0.89 ms and in masseters 24 +/- 0.75 ms. In patients with mandibular fractures the time of periodontal muscular reflex was increased up to 3-4-fold as compared to that in normal subjects. The indices of the reflex are clearly different in normal and pathological conditions. This technique is useful both in scientific and diagnostic purposes. PMID:2749808

Malevich, O E; Zhitni?, N I; Chirkin, V I; Ivashenko, M V

1989-01-01

67

Personal Branding and the Commodification of Reflexivity  

Microsoft Academic Search

Reflexivity as a concept has produced theoretical debates which have explored the relationship of social actors to agency and identity. Less attention has been paid to reflexivity as a commodity, that is, to the forms of reflexivity that different actors display and to the appropriateness of these forms. Actors who display appropriate forms of reflexivity are likely to be treated

Lionel Wee; Ann Brooks

2010-01-01

68

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

PubMed

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

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

2010-06-01

69

Reflexivity in precompact groups and extensions  

E-print Network

We establish some general principles and find some counter-examples concerning the Pontryagin reflexivity of precompact groups and P-groups. We prove in particular that: (1) A precompact Abelian group G of bounded order is reflexive iff the dual group $\\hat{G}$ has no infinite compact subsets and every compact subset of G is contained in a compact subgroup of G. (2) Any extension of a reflexive P-group by another reflexive P-group is again reflexive. We show on the other hand that an extension of a compact group by a reflexive $\\omega$-bounded group (even dual to a reflexive P-group) can fail to be reflexive. We also show that the P-modification of a reflexive $\\sigma$-compact group can be nonreflexive (even if the P-modification of a locally compact Abelian group is always reflexive).

Bruguera, Monteserrat; Hernández, Constancio; Tkachenko, Mikhail

2012-01-01

70

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

Microsoft Academic Search

The present study explored anxious apprehension in panic disorder patients and controls in two threat conditions, darkness and threat of shock. Autonomic arousal and startle eyeblink reflexes were recorded in 26 panic disorder patients and 22 controls during adaptation, a safe condition, threat of shock, and darkness. Exposure to darkness resulted in a clear potentiation of the startle reflex. Panic

Christiane A. Melzig; Almut I. Weike; Jörg Zimmermann; ALFONS O. HAMMa

2007-01-01

71

Jaw stretch reflexes in children.  

PubMed

The substantial morphological transformations that occur during human development present the nervous system with a considerable challenge in terms of motor control. Variability of skilled motor performance is a hallmark of a developing system. In adults, the jaw stretch reflex contributes to the functional stability of the jaw. We have investigated the response properties of the jaw stretch reflex in two groups of young children and a group of young adults. Response latencies increased with development, and all age groups produced stimulus-magnitude-dependent increases in reflex gain and resulting biting force. Reflex gain was largest for the older children (9-10 years), yet net increases in resulting biting force were comparable across age groups. These data and earlier experiments suggest that oral sensorimotor pathways mature throughout childhood in concert with the continued acquisition of complex motor skills. PMID:15981018

Finan, Donald S; Smith, Anne

2005-07-01

72

Volitional control of reflex cough.  

PubMed

Multiple studies suggest a role for the cerebral cortex in the generation of reflex cough in awake humans. Reflex cough is preceded by detection of an urge to cough; strokes specifically within the cerebral cortex can affect parameters of reflex cough, and reflex cough can be voluntarily suppressed. However, it is not known to what extent healthy, awake humans can volitionally modulate the cough reflex, aside from suppression. The aims of this study were to determine whether conscious humans can volitionally modify their reflexive cough and, if so, to determine what parameters of the cough waveform and corresponding muscle activity can be modified. Twenty adults (18-40 yr, 4 men) volunteered for study participation and gave verbal and written informed consent. Participants were seated and outfitted with a facemask and pneumotacograph, and two surface EMG electrodes were positioned over expiratory muscles. Capsaicin (200 ?M) was delivered via dosimeter and one-way (inspiratory) valve attached to a side port between the facemask and pneumotachograph. Cough airflow and surface EMG activity were recorded across tasks including 1) baseline, 2) small cough (cough smaller or softer than normal), 3) long cough (cough longer or louder than normal), and 4) not cough (alternative behavior). All participants coughed in response to 200 ?M capsaicin and were able to modify the cough. Variables exhibiting changes include those related to the peak airflow during the expiratory phase. Results demonstrate that it is possible to volitionally modify cough motor output characteristics. PMID:22492938

Hegland, Karen W; Bolser, Donald C; Davenport, Paul W

2012-07-01

73

Possible mechanisms of the involvement of dopaminergic cells and cholinergic interneurons in the striatum in the conditioned-reflex selection of motor activity.  

PubMed

A possible mechanism for the involvement of cholinergic interneurons in the striatum and dopaminergic cells in the substantia nigra in the selection from among several types of motor activity during learning is proposed. Selection is triggered by simultaneous increases in the activity of dopaminergic neurons and a pause in the activity of cholinergic interneurons in response to the conditioned signal. The appearance of the pause may facilitate activation of GABAergic interneurons in the striatum and the action of dopamine on D2 receptors on cholinergic interneurons. Differently directed changes in dopamine and acetylcholine levels synergistically modulate the efficiency of corticostriatal inputs, such that the rules for modulation of the "strong" and "weak" inputs are opposite in sign. The subsequent reorganization of neuron activity in the cortex-basal ganglia-thalamus-cortex circuit leads to increased activity in those cortical neurons providing "strong" innervation to the striatum with simultaneous decreases in the activity of neurons providing "weak" innervation to the striatum, which may underlie the selection of the movement reaction, in which the neocortex is involved. It follows from this model that if the delay between the conditioned and unconditioned stimuli is not longer than the latent period of the reactions of dopaminergic and cholinergic cells (about 100 msec), selection of movement activity in response to the conditioned signal and learning is hindered. PMID:16380830

Sil'kis, I G

2006-02-01

74

Reflex seizures in Rett syndrome.  

PubMed

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

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

2011-12-01

75

Independent control of reflex and volitional EMG modulation during sinusoidal pursuit tracking in humans  

Microsoft Academic Search

It is well known that during volitional sinusoidal tracking the long-latency reflex modulates in parallel with the volitional EMG activity. In this study, a series of experiments are reported demonstrating several conditions in which an uncoupling of reflex from volitional activity occurs. The paradigm consists of a visually guided task in which the subject tracked a sinusoid with the wrist.

M. T. V. Johnson; A. N. Kipnis; M. C. Lee; T. J. Ebner

1993-01-01

76

Brane Tilings and Reflexive Polygons  

E-print Network

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

Amihay Hanany; Rak-Kyeong Seong

2012-01-12

77

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

PubMed Central

This study characterizes tonic and phasic stretch reflex and stiffness and viscosity changes associated with spastic hemiparesis. Perturbations were applied to the ankle of 27 hemiparetic and 36 healthy subjects under relaxed or active contracting conditions. A nonlinear delay differential equation model characterized phasic and tonic stretch reflex gains, elastic stiffness, and viscous damping. Tendon reflex was characterized with reflex gain and threshold. Reflexively, tonic reflex gain was increased in spastic ankles at rest (P < 0.038) and was not regulated with muscle contraction, indicating impaired tonic stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction (P < 0.012) than controls (P < 0.023) and higher in dorsi-flexors at lower torques (P < 0.038), primarily because of its increase at rest (P = 0.045), indicating exaggerated phasic stretch reflex especially in more spastic plantar flexors, which showed higher phasic stretch reflex gain than dorsi-flexors (P < 0.032). Spasticity was associated with increased tendon reflex gain (P = 0.002) and decreased threshold (P < 0.001). Mechanically, stiffness in spastic ankles was higher than that in controls across plantar flexion/dorsi-flexion torque levels (P < 0.032), and the more spastic plantar flexors were stiffer than dorsi-flexors at comparable torques (P < 0.031). Increased stiffness in spastic ankles was mainly due to passive stiffness increase (P < 0.001), indicating increased connective tissues/shortened fascicles. Viscous damping in spastic ankles was increased across the plantar flexion torque levels and at lower dorsi-flexion torques, reflecting increased passive viscous damping (P = 0.033). The more spastic plantar flexors showed higher viscous damping than dorsi-flexors at comparable torque levels (P < 0.047). Simultaneous characterizations of reflex and nonreflex changes in spastic hemiparesis may help to evaluate and treat them more effectively. PMID:23636726

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

2013-01-01

78

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

PubMed

This study characterizes tonic and phasic stretch reflex and stiffness and viscosity changes associated with spastic hemiparesis. Perturbations were applied to the ankle of 27 hemiparetic and 36 healthy subjects under relaxed or active contracting conditions. A nonlinear delay differential equation model characterized phasic and tonic stretch reflex gains, elastic stiffness, and viscous damping. Tendon reflex was characterized with reflex gain and threshold. Reflexively, tonic reflex gain was increased in spastic ankles at rest (P < 0.038) and was not regulated with muscle contraction, indicating impaired tonic stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction (P < 0.012) than controls (P < 0.023) and higher in dorsi-flexors at lower torques (P < 0.038), primarily because of its increase at rest (P = 0.045), indicating exaggerated phasic stretch reflex especially in more spastic plantar flexors, which showed higher phasic stretch reflex gain than dorsi-flexors (P < 0.032). Spasticity was associated with increased tendon reflex gain (P = 0.002) and decreased threshold (P < 0.001). Mechanically, stiffness in spastic ankles was higher than that in controls across plantar flexion/dorsi-flexion torque levels (P < 0.032), and the more spastic plantar flexors were stiffer than dorsi-flexors at comparable torques (P < 0.031). Increased stiffness in spastic ankles was mainly due to passive stiffness increase (P < 0.001), indicating increased connective tissues/shortened fascicles. Viscous damping in spastic ankles was increased across the plantar flexion torque levels and at lower dorsi-flexion torques, reflecting increased passive viscous damping (P = 0.033). The more spastic plantar flexors showed higher viscous damping than dorsi-flexors at comparable torque levels (P < 0.047). Simultaneous characterizations of reflex and nonreflex changes in spastic hemiparesis may help to evaluate and treat them more effectively. PMID:23636726

Zhang, Li-Qun; Chung, Sun G; Ren, Yupeng; Liu, Lin; Roth, Elliot J; Rymer, W Zev

2013-07-01

79

The Reflexive Suffix -V In Hualapai  

E-print Network

Like many other languages Hualapai employs the reflexive suffix for several different grammatical purposes. Unlike them, however, constructions with a reflexive marker in Hualapai are usually not ambiguous with respect to the expected meanings...

Sohn, Joong-Sun

1995-01-01

80

The history of examination of reflexes.  

PubMed

In the late 1800s, Wilhelm Erb, Joseph Babinski, William Gowers, and others helped develop the neurologic examination as we know it today. Erb was one of the first to emphasize a detailed and systematic neurologic exam and was co-discoverer of the muscle stretch reflex, Gowers began studying the knee jerk shortly after it was described, and Babinski focused on finding reliable signs that could differentiate organic from hysterical paralysis. These physicians and others emphasized the bedside examination of reflexes, which have been an important part of the neurologic examination ever since. This review will focus on the history of the examination of the following muscle stretch and superficial/cutaneous reflexes: knee jerk, jaw jerk, deep abdominal reflexes, superficial abdominal reflexes, plantar reflex/Babinski sign, and palmomental reflex. The history of reflex grading will also be discussed. PMID:24695995

Boes, Christopher J

2014-12-01

81

Adapting reflexes controlling the human posture  

Microsoft Academic Search

Doubt about the role of stretch reflexes in movement and posture control has remained in part because the questions of reflex “usefulness” and the postural “set” have not been adequately considered in the design of experimental paradigms. The intent of this study was to discover the stabilizing role of stretch reflexes acting upon the ankle musculature while human subjects performed

L. M. Nashner

1976-01-01

82

Reflexive practice: To enhance student learning  

Microsoft Academic Search

This paper reports on the use of reflexive practice activities designed to enhance learning for first year law students at James Cook University, Australia. The paper considers various aspects of student learning and explores connections between reflexive practice and concepts such as deep learning, understanding, motivation and engagement, and identifies abilities developed by reflexive practice. The paper explores terms such

Joanne Roebuck

2007-01-01

83

Are there clinical features of a sensitized cough reflex?  

PubMed

Cough reflex hypersensitization is a key feature in patients with troublesome cough. The clinical consequence of this hypersensitive state is typified by bouts of coughing often triggered by low threshold stimuli encountered by the patient during normal daily activities including exposure to aerosols, scents and odours, a change in air temperature and when talking or laughing. These features are often perceived by cough patients to be the most disruptive aspect of their condition and undoubtedly contribute to impaired quality of life. Patients with troublesome cough may describe a range of additional symptoms and sensations including an 'urge to cough' or the feeling of an 'itch' at the back of the throat, or a choking sensation and occasionally chest pain or breathlessness. It is uncertain if these features arise due to the processes responsible for cough reflex sensitization or as a direct consequence of the underlying cough aetiology. In an attempt to understand the clinical features of a sensitized cough reflex, the spectrum of symptoms typically described by cough patients will be reviewed and possible underlying mechanisms considered. Since an intact cough reflex is crucial to airway protection, anti-tussive treatment that attenuates the hypersensitive cough state rather than abolishing the cough reflex completely would be preferable. Identifying such agents remains a clinical, scientific and pharmacological challenge. PMID:19049891

McGarvey, L; McKeagney, P; Polley, L; MacMahon, J; Costello, R W

2009-04-01

84

Reflexive Expectation Formation Timo Ehrig  

E-print Network

Reflexive Expectation Formation Timo Ehrig J¨urgen Jost Abstract How do economic agents form expectations regarding asset prices and the development of macroeconomic quantities, when of expectations fold back to the realized economic process, and in particular, to the selection of one of multiple

Jost, Jürgen

85

Vortex equation and reflexive sheaves  

E-print Network

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

Indranil Biswas; Matthias Stemmler

2011-11-28

86

The Reflexive Relationship between Computer Games Technology and the Law  

Microsoft Academic Search

Computer Games Technology (CGT) is an important phenomenon in the evolution of the relationship between Communications Technology (CT) and the law. CGT is reflexively linked with the evolution of law. Thus (for example) the development of CGT is conditioned, and will continue to be affected, by the evolution of law and legal principles. The legal domains of Intellectual Property (IP)

JAMES TUNNEY

87

Trigeminocardiac reflexes: maxillary and mandibular variants of the oculocardiac reflex  

Microsoft Academic Search

Three case reports are presented to illustrate the existence and importance of reflex bradycardic responses that can occur\\u000a during maxillofacial surgical procedures. All three patients were healthy young adults undergoing operations which did not\\u000a include any manipulation of orbital structures. After the patients had been anaesthetized for some time and were haemodynamically\\u000a stable, profound bradycardia or ventricular asystole occurred suddenly

Scott Lang; Dennis T. Lanigan; Mike van der Wal

1991-01-01

88

Intracranial causes of ophthalmoplegia: the visual reflex pathways.  

PubMed

The gathering of visual information is a complex process that relies on concerted movements of the eyes, and cranial nerves II-VIII are at least partially involved in the visual system. The cranial nerves do not function in isolation, however, and there are multiple higher-order cortical centers that have input into the cranial nerves to coordinate eye movement. Among the functions of the cortical reflex pathways are (a) controlling vertical and horizontal gaze in response to vestibular input to keep the eyes focused on an object as the head moves through space, and (b) controlling rapid, coordinated eye movement to a new visual target (saccades). There are also reflex pathways connecting the cranial nerves involved in vision that produce consensual blinking of the eyes in response to corneal stimulation of one eye and consensual pupillary constriction in response to light input on one pupil. A variety of intracranial pathologic conditions, including benign and malignant neoplasms, infection, trauma, autoimmune diseases, vascular anomalies, degenerative diseases, and inherited-congenital disorders, can disrupt the cranial nerves and visual reflex pathways. This disruption can manifest in myriad ways-for example, as extraocular muscle paresis, afferent pupillary defect, oculosympathetic paresis (Horner syndrome), internuclear ophthalmoplegia, dorsal midbrain (Parinaud) syndrome, or loss of the corneal reflex. Knowledge of the function and anatomy of the cranial nerves and visual reflex pathways, coupled with selection of the proper magnetic resonance pulse sequence, will allow the radiologist to order appropriate imaging of the involved cranial nerve or visual reflex pathway based on the patient's symptoms and thereby play an essential role in establishing the diagnosis and planning appropriate therapy. PMID:24025940

Stalcup, Seth T; Tuan, August S; Hesselink, John R

2013-01-01

89

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

90

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

91

[Reflexivity: a critical issue in qualitative research].  

PubMed

Reflexivity is an English term that Spanish speaking people have to assign a technical meaning. Reflexivity expresses the conscience of researchers conscience and refers to their connection with the study's situation. It is a process by which researchers step back to critically exam the effect they have on the study and the impact of their interactions with participants. The reflexive process is embedded in all research levels and is present in all the research phases, from the research question to fieldwork, from data analysis to writing the final report. Nevertheless, the question is not so much to engage in reflective activities but to be a reflexive researcher. Reflexivity is a human ability that is present during social interactions. For this reason it is present in qualitative research. A self inquirer can be addressed as it is constructed by the relationships and interactions that are established with study participants. Reflexivity has an educational character that continues after the study is completed. PMID:21531602

de la Cuesta-Benjumea, Carmen

2011-01-01

92

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

PubMed Central

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

Szabadi, Elemer

2012-01-01

93

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

ERIC Educational Resources Information Center

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

Myklebust, Barbara M.; Gottlieb, Gerald L.

1993-01-01

94

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

PubMed

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

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

2013-12-01

95

Stable reflexive sheaves and localization  

E-print Network

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

Gholampour, Amin

2013-01-01

96

Acousticomotor reflexes M Dolores E. Lpez Garca  

E-print Network

Tympanic Ear Drum Incus Stapedius Eustachian Tube Tympanic cavity Stapes Malleus 1- Middle ear reflex1 Membrane (Ear Drum) Incus Stapedius Eustachian Tube Tympanic cavity Stapes Malleus · Involuntary bilateral for the organism is analyzed since they are responsible for protecting the auditory receptor (middle-ear reflexes

Oliver, Douglas L.

97

The Reflex Mechanism of the Insect Leg  

Microsoft Academic Search

1. Variations in the frequency of the motor discharges to the leg muscles of Periplaneta americana are followed in the intact animal under different types of sensory stimulation by electrical recording from the muscles.2. Two main reflexes are described: the depressor reflex, evoked by stimulation of the campaniform sensilla on the legs, and a levator response to touch on the

J. W. S. Pringle

1940-01-01

98

Functional organization of the nociceptive withdrawal reflexes  

Microsoft Academic Search

The spatial organization of the cutaneous input to hindlimb withdrawal reflexes was studied in spinalized, decerebrated, unanesthetized rats. Reflex activity in plantar flexors of the digits, pronators of the foot, dorsiflexors of the digits, and\\/or the ankle and flexors of the knee was recorded with electromyographic techniques for up to 12 h after spinalization. Graded mechanical (pinch) and thermal stimulation

Jens Schouenborg; Hans Holmberg; Han-Rong Weng

1992-01-01

99

Effect of capsaicin on micturition and associated reflexes in chronic spinal rats  

Microsoft Academic Search

The role of capsaicin-sensitive bladder afferents in micturition was studied in unanesthetized chronic spinal rats. Reflex voiding in response to tactile stimulation of the perigenital region appeared 5–9 days after spinal cord injury (SCI) whereas voiding induced by bladder distension occurred 2–3 weeks after SCI. The frequency and amplitude of reflex bladder contractions recorded under isovolumetric conditions were similar in

Chen-Li Cheng; Cheng-Ping Ma; William C. de Groat

1995-01-01

100

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

101

Stable reflexive sheaves and localization  

E-print Network

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

Amin Gholampour; Martijn Kool

2013-08-16

102

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

103

Abnormal oculocardiac reflex in two patients with Marcus Gunn syndrome  

PubMed Central

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

2011-01-01

104

Demonstrating the Stretch Reflex: A Mechanical Model.  

ERIC Educational Resources Information Center

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

Batavia, Mitchell; McDonough, Andrew L.

2000-01-01

105

Relationship of Postural Reflexes to Learning Disabilities  

ERIC Educational Resources Information Center

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

Rider, Barbara A.

1972-01-01

106

Reflexive Operator Algebras on Banach Spaces  

E-print Network

In this paper we study the reflexivity of a unital strongly closed algebra of operators with complemented invariant subspace lattice on a Banach space. We prove that if such an algebra contains a complete Boolean algebra of projections of finite uniform multiplicity and with the direct sum property, then it is reflexive, i.e. it contains every operator that leaves invariant every closed subspace in the invariant subspace lattice of the algebra. In particular, such algebras coincide with their bicommutant.

Merlevède, Florence; Peligrad, Magda

2012-01-01

107

Somatosensory and acoustic brain stem reflex myoclonus.  

PubMed Central

A patient with brain stem reflex myoclonus due to a massive midbrain infarct was studied electrophysiologically. Myoclonic jerks were elicited at variable latencies by tapping anywhere on the body or by acoustic stimuli, and mainly involved flexor muscles of upper extremities. The existence of convergence of somatosensory and acoustic inputs in the brain stem was suggested. This myoclonus seemed to be mediated by a mechanism similar to the spino-bulbo-spinal reflex. PMID:3379432

Shibasaki, H; Kakigi, R; Oda, K; Masukawa, S

1988-01-01

108

Reflexive Anaphora Resolution in Pashto Discourse  

Microsoft Academic Search

The paper presents a rule-based approach for the reflexive pronouns (ReflPro(s)) resolution problem in Pashto language. Here, first the rules are described and exemplified and then the algorithm for identifying the noun phrase antecedents of reflexive anaphors is developed. Finally, the proposed algorithm is evaluated against a manually annotated Pashto corpus. The algorithm successfully identifies the antecedents of about 87.0%

Rahman Ali; Mohammad Abid Khan; Mushtaq Ali

2009-01-01

109

Modulation of Ankle Muscle Postural Reflexes in Stroke: Influence of Weight-bearing Load  

PubMed Central

Objective Given the known sensorimotor deficits and asymmetric weight-bearing posture in stroke, the aim of this study was to determine whether stroke affects the modulation of standing postural reflexes with varying weight-bearing load. Methods Ten individuals with chronic stroke and 10 healthy older adult controls were exposed to unexpected forward and backward platform translations while standing. Three different stance conditions were imposed: increased weight-bearing load, decreased weight-bearing load, and self-selected stance. Surface EMG from bilateral ankle dorsiflexors (tibialis anterior) and extensors (gastrocnemius) were recorded and the magnitude of background muscle activity (prior to the platform translation) and postural reflex onset latency and magnitude (75 ms following reflex onset) were determined. Results Load modulation of ankle extensors was found in controls and individuals with stroke. Although controls demonstrated modulation of ankle dorsiflexors to different loads, individuals with stroke did not show this modulation. Further, load did not change the onset latency of postural reflexes of the individuals with stroke. Conclusion The delayed paretic muscle onset latencies in conjunction with impaired modulation of ankle dorsiflexor postural reflexes may contribute to the instability and frequent falls observed among individuals with stroke. Significance The results provide some insight into standing postural reflexes following stroke. PMID:15546787

Marigold, Daniel S.; Eng, Janice J.; Inglis, J. Timothy

2011-01-01

110

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

111

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

PubMed Central

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

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

2012-01-01

112

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

PubMed Central

Background Our previous work showed a beneficial therapeutic effect on blepharospasm using slow repetitive transcranial magnetic stimulation which produces a long-term depression-like effect. High-frequency supraorbital electrical stimulation, asynchronous with the R2 component of the blink reflex, can also induce long-term depression-like effects on the blink reflex circuit in healthy subjects. Patients with blepharospasm have reduced inhibition of their blink recovery curves; therefore, a long-term depression-like intervention might normalize the blink reflex recovery and have a favorable therapeutic effect. Methods This is a randomized, sham-controlled, observer-blinded prospective study. In 14 blepharospasm patients, we evaluated the effects of high-frequency supraorbital stimulation on three separate treatment days. We applied 28 trains of 9 stimuli, 400 Hertz, either BEFORE or AFTER the R2 or used SHAM stimulation. The primary outcome was the blink rate, number of spasms rated by a blinded physician and patient rating before, immediately after and 1 hour after stimulation while resting, reading, and talking; secondary outcome was the blink reflex recovery. Results Stimulation-BEFORE and stimulation-AFTER the R2 both showed a similar improvement as SHAM-stimulation in physician rating, but patients felt significantly better with the BEFORE condition. Improvement in recovery of the blink reflex was seen only in the BEFORE condition. Clinical symptoms differed in the three baseline conditions (resting, reading, talking). Conclusions Stimulation BEFORE R2 increased inhibition in trigeminal blink reflex circuits in blepharospasm toward normal values and produced subjective but not objective improvement. Inhibition of the blink reflex pathway by itself appeared to be insufficient for a useful therapeutic effect. PMID:23401198

Kranz, G.; Shamim, E.A.; Lin, P.T.; Kranz, G.S.; Hallett, M.

2012-01-01

113

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

114

Reflex sympathetic dystrophy: Skin blood flow, sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy  

Microsoft Academic Search

To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, skin resistance and skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four

R. Baron; C. Maier

1996-01-01

115

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

Microsoft Academic Search

The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex- and age-matched controls were selected. In subgroups of

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

2002-01-01

116

Age, functional postural reflexes, and voluntary sway.  

PubMed

This experiment considered age-related changes in functional relationships between postural reflexes and voluntary movement. Young and older adults received horizontal perturbations during normal stance and when engaged in voluntary sway. Electromyographic activity showed that (a) older adults had poorer coordination between postural reflexes and voluntary movement, and (b) their stabilizing responses to postural disturbances during voluntary sway were slower. In addition, the onsets of activity of functionally important muscles were less tightly bilaterally coupled, and patterns of muscle onsets were less stereotypically organized in older adults. The results suggest that older adults experience some breakdown in the timing and sequencing of muscle activity and in the functional coordination of their postural reflexes with voluntary sway. PMID:2738304

Stelmach, G E; Phillips, J; DiFabio, R P; Teasdale, N

1989-07-01

117

Classification of Reflexive Polyhedra in Three Dimensions  

E-print Network

We present the last missing details of our algorithm for the classification of reflexive polyhedra in arbitrary dimensions. We also present the results of an application of this algorithm to the case of three dimensional reflexive polyhedra. We get 4319 such polyhedra that give rise to K3 surfaces embedded in toric varieties. 16 of these contain all others as subpolyhedra. The 4319 polyhedra form a single connected web if we define two polyhedra to be connected if one of them contains the other.

M. Kreuzer; H. Skarke

1998-05-27

118

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

Microsoft Academic Search

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,

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

2005-01-01

119

Rhythmic leg cycling modulates forearm muscle H-reflex amplitude and corticospinal tract excitability.  

PubMed

Rhythmic arm cycling leads to suppression of H-reflexes in both leg and arm muscles, and a reduction in the excitability of corticospinal projections to the forearm flexors. It is unknown, however, whether leg cycling modulates excitability in neural projections to the arms. Here we studied the extent to which rhythmic movement of the legs alters reflex (Experiment 1) and corticospinal (Experiment 2) transmission to arm muscles. In experiment 1, flexor carpi radialis (FCR) H-reflex recruitment curves were recorded with the legs static, and during rhythmic leg movement, while the FCR was both contracted and relaxed. The results indicate that rhythmic leg movement suppresses reflex transmission, both when FCR is at rest and during tonic contraction, but that the effect is not phase-dependent. In experiment 2, we used transcranial magnetic stimulation (TMS) to elicit motor-evoked potentials in the contracted and relaxed FCR during static leg, and leg cycling conditions. Sub-threshold TMS was also used to condition H-reflexes in order to provide specific information about cortical excitability during leg cycling. Both resting and tonically contracting arm muscles showed a greater corticospinal excitability during leg cycling than during the static leg condition. The magnitude of TMS facilitation of H-reflexes was similar during leg cycling and rest, suggesting a considerable sub-cortical component to the increased corticospinal excitability. The results suggest a differential regulation of afferent and descending projections to the arms during leg cycling, and are consistent with the idea that there is a loose, but significant, neural coupling between the arms and legs during rhythmic movement. PMID:17452078

Zehr, E Paul; Klimstra, Marc; Johnson, Elizabeth A; Carroll, Timothy J

2007-05-23

120

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

ERIC Educational Resources Information Center

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

Minderaa, Ruud B.; And Others

1985-01-01

121

Writing in the Disciplines Strategies for Reflexive Writing  

E-print Network

See over Writing in the Disciplines Strategies for Reflexive Writing 1. Understand the role of selfreflection in "writing to learn/learning to write" In reflexive (selfreflective) writing, you couple. As well as sharing insights with readers, reflexive writing is increasingly becoming "an important

122

On Reflection: Is Reflexivity Necessarily Beneficial in Intercultural Education?  

ERIC Educational Resources Information Center

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

Blasco, Maribel

2012-01-01

123

Reflex control of the prototype leg during contact and slippage  

Microsoft Academic Search

A formulation of reflex control is presented which has been developed and used in the control of a prototype leg of the adaptive suspension vehicle to implement reflex actions. In particular, the concept of reflex control has been demonstrated experimentally in high-speed contact and foot slippage. A constraint analysis of the leg-environment interaction is found to be especially useful in

Ho Cheung Wong; David E. Orin

1988-01-01

124

Experimental research of the pupil light reflex  

NASA Astrophysics Data System (ADS)

This paper reports the method of recording the Pupil Light Reflex with using a CCD linear sensor as a detector. The system allows to obtain a linear resolution 0,005 mm and a temporary resolution 11 ins. The principle of measuring method and example results of PLR study are presented.

Szczepanowska, Wioletta; Kasprzak, Henryk T.; Hachol, Andrzej

2003-11-01

125

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

126

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

127

On Becoming a Critically Reflexive Practitioner  

ERIC Educational Resources Information Center

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

Cunliffe, Ann L.

2004-01-01

128

Reflex sympathetic dystrophy in a child  

Microsoft Academic Search

We describe a 9 1\\/2 year old girl who suffered from severe recurrent pain and functional limitation in her right leg with hyperesthesia, hyperalgesia, color change and edema as the presenting symptoms, during the previous two months. All laboratory tests were found to be normal and diagnosis of reflex sympathetic dystrophy was made.

U. Brook; A. Hanukuglo; M. Heim

1992-01-01

129

Atomic compactness and reflexive graphs. Christian DELHOMM '  

E-print Network

Atomic compactness and reflexive graphs. Christian DELHOMM ' E Universit¨at Bielefeld Abstract A first order structure M with universe M is atomic compact if every system of atomic formulas with parameters in M is satisfiable in M provided each of its finite subsystems is. The definition of atomic

Bielefeld, University of

130

The Reflexive Modernization of Australian Universities  

ERIC Educational Resources Information Center

The profound changes occurring in Australian higher education are viewed here in the context of the social, cultural, political and economic effects of globalization. Particular attention is paid to providing a theoretical foundation for understanding these effects using the reflexive modernization perspective. Highlighted are some of the…

Pick, David

2004-01-01

131

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

132

Motor Cortex Reflexes Associated with Learned Movement  

Microsoft Academic Search

In primates, sensory input can generate reflex motor cortex output in association with learned movement when the sensory input has a strong and direct connection to the motor cortex-for example, when a stimulus calling for repositioning of the hand consists of a perturbation of hand position. This finding supports the proposal that neurons of primate motor cortex may function in

Edward V. Evarts

1973-01-01

133

The Pectoralis Cross Reflex in Man  

Microsoft Academic Search

A pectoralis cross reflex was described. It is indicative of a pyramidal tract lesion. It was detected in patients with cervical cord pathology. Some of those patients had cervical cord compression; myelogram showed partial or complete block, due to tumors, cervical spondylosis, fracture, subluxation, herniated disc or any other space-occupying lesion between C-1 and C-6. The importance of the pectoralis

J. Moldaver

1972-01-01

134

INTERACTIVE REFLEXIVE MUSICAL SYSTEMS FOR MUSIC EDUCATION  

Microsoft Academic Search

The present paper deals with a research project currently being undertaken at the Faculty of Education, University of Bologna, in collaboration with François Pachet from SONY-Computer Science Laboratory, in Paris. Our project collects and develops experiments about music education and the Interactive Reflexive Musical Systems. The IRMS are systems in which the user, whatever his competences' level, is confronted with

Anna Rita Addessi

135

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

136

Munchausen's syndrome simulating reflex sympathetic dystrophy  

Microsoft Academic Search

A 15 year old girl who had pain, oedema of her left hand, and fever of four months' duration is described. Marked demineralisation of her hand was shown by radiography, and increased articular uptake by technetium-99m bone scan. All these changes were indistinguishable from reflex sympathetic dystrophy. After two admissions to hospital and multiple explorations we discovered that she had

J Rodriguez-Moreno; J M Ruiz-Martin; L Mateo-Soria; A Rozadilla; D Roig-Escofet

1990-01-01

137

A study on the forearm muscular reflexes during grasping for prosthetic applications.  

PubMed

Recently, there has been an increasing interest in upper-limb prosthetic hand control, but most of these studies focus on the detection of exact motion intentions. Therefore, the responses to unexpected disturbance are not taken into consideration. On the other hand, unimpaired people respond to external disturbances by reflexive responses, hence, it is important to explore how this kind of reactive responses could be applied into prosthetic hand applications, and whether it will improve the human-machine interaction in a dynamical way. Our objective for the present study was to examine the responses of the human reflexes on different conditions in order to apply them to our prosthetic hand. Electromyograph (EMG) signals were recorded from the forearm muscles of unimpaired people during grasping of a cylinder. Results showed that the reflexes have different tendencies depending on the direction on which the disturbance is applied. PMID:21096654

Soma, Hirokazu; Horiuchi, Yuse; Gonzalez, Jose; Yu, Wenwei

2010-01-01

138

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

NASA Technical Reports Server (NTRS)

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

Komendantov, G. L.

1973-01-01

139

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

E-print Network

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

140

Reflexivity and Globalisation: some challenges for research and evaluation into quality education mediated by ICTs  

Microsoft Academic Search

Globalisation can be characterised, Giddens (1994) suggests, as a process of 'intensified reflexivity' that creates the conditions for 'a world of clever people'. Information and Communication Technologies (ICTs) are fundamental to globalisation and they have also been incorporated into the new educational technologies deployed by educators to (re)create 'a world of clever people'. Together, education and the ICTs are strong

Terry Evans

141

Pupil light reflex in the Atlantic brief squid, Lolliguncula brevis.  

PubMed

Coleoid behavioral ecology is highly visual and requires an eye capable of forming images in a variety of photic conditions. A variable pupil aperture is one feature that contributes to this visual flexibility in most coleoids, although pupil responses have yet to be quantitatively documented for squid. The pupil light reflex (PLR) of the Atlantic brief squid, Lolliguncula brevis, was analyzed by directly exposing one eye of individual squid to light stimuli of varying irradiance and imaging the reflex, while simultaneously recording from the opposite, indirectly stimulated eye to determine whether the constriction was consensual between eyes. A PLR was measured in L. brevis, with an asymmetrical constriction observed under increasing irradiance levels that was not consensual between eyes, although a response of some level was observed in both eyes. Response thresholds ranged between 12.56 and 12.66 log photons cm(-2) s(-1). The PLR was rapid and dependent upon the stimulus irradiance, achieving half-maximum constriction within 0.49-1.2 s. The spectral responsivity of the PLR was analyzed by measuring the magnitude of the reflex in the eye directly stimulated by light of equal quantal intensity at wavelengths from 410 to 632 nm. The responsivity curve showed a maximum at 500 nm, indicating the eye is especially well suited for vision at twilight. These results, when considered in the context of the ambient light characteristics, show that the PLR of L. brevis contributes to a dynamic visual system capable of adjusting to the highly variable composition of light in its estuarine habitat. PMID:22786645

McCormick, Lillian R; Cohen, Jonathan H

2012-08-01

142

Modulation of the initial light reflex during affective picture viewing.  

PubMed

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

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

2014-09-01

143

Effect of chronic and acute cigarette smoking on the pharyngo-upper oesophageal sphincter contractile reflex and reflexive pharyngeal swallow  

PubMed Central

Background—Cigarette smoking is known to affect adversely the defence mechanisms against gastro-oesophageal reflux. The effect of smoking on the supraoesophageal reflexes that prevent aspiration of gastric contents has not been previously studied. ?Aims—To elucidate the effect of cigarette smoking on two of the supraoesophageal reflexes: the pharyngo-upper oesophageal sphincter (UOS) contractile reflex; and the reflexive pharyngeal swallow. ?Methods—Ten chronic smokers and 10 non-smokers were studied, before and 10 minutes after real or simulated smoking, respectively. UOS pressure and threshold volume for the reflexes were determined using a UOS sleeve assembly. Two modes of fluid delivery into the pharynx were tested: rapid injection and slow injection. ?Results—For both rapid and slow injections, the threshold volume for triggering the pharyngo-UOS contractile reflex was significantly higher in smokers than in non-smokers (rapid: smokers 0.42 (SE 0.07) ml, non-smokers 0.16 (0.04) ml; slow: smokers 0.86 (0.06) ml, non-smokers 0.38 (0.1) ml; p<0.05). During rapid injection, the threshold volume for reflexive pharyngeal swallow was higher in smokers (smokers 0.94 (0.09) ml, non-smokers 0.46 (0.05) ml; p<0.05). Acute smoking further increased the threshold volume for the pharyngo-UOS contractile reflex and reflexive pharyngeal swallow during rapid injection. ?Conclusions—Smoking adversely affects stimulation of the pharyngo-UOS contractile reflex and pharyngeal reflexive swallow. These findings may have implications in the development of reflux related respiratory complications among smokers. ?? Keywords: smoking; supraoesophageal reflexes; pharyngo-upper oesophageal sphincter contractile reflex; reflexive pharyngeal swallow; airway protection; gastro-oesophageal reflux PMID:9824582

Dua, K; Bardan, E; Ren, J; Sui, Z; Shaker, R

1998-01-01

144

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

145

Intraoperative recording of the bulbocavernosus reflex.  

PubMed

: The bulbocavernosus reflex (BCR) is mediated by the sacral somatic afferent/efferent periphery as well as the sacral cord. Unfortunately, the reflex has suffered from a partly deserved reputation as difficult to implement. However, recent stratagems have improved the test's reliability. Multipulse stimulation (enhanced by double trains as required) and exacting recording technique can yield positive and remarkably reproducible results in patients of all ages and either sex. In this review, we document a 94% baseline BCR acquisition rate among 100 consecutive cases in one institution. Acceptance and routine use of the BCR is needed to help assure optimal post-operative low sacral function in intradural and extradural surgeries at the level of conus medullaris, cauda equina, sacral plexus, and the pudendal nerve. Case studies within this review illustrate the power of the BCR to predict patient outcome or, much more importantly, reverse incipient patient injury in real time. PMID:25083842

Skinner, Stanley A; Vodušek, David B

2014-08-01

146

Exaggerated postural vasoconstrictor reflex in Raynaud's phenomenon.  

PubMed Central

The central and local regulation of capillary blood flow in the finger was studied by the local xenon-133 washout technique in women with primary Raynaud's phenomenon, men with vibration induced white finger, and their respective sex matched controls. The vasoconstrictor response to venous stasis of 40 mm Hg elicited by local reflex was normal in both types of Raynaud's phenomenon. Change in posture from lying to sitting induced vasoconstriction in all groups, which was abolished by proximal nervous blockade. The vasoconstrictor response to sitting was augmented in both groups of subjects with Raynaud's phenomenon compared with their sex matched controls. These results show the existence of central and local postural vasoconstrictor reflexes in normal fingers. In both types of Raynaud's phenomenon there was hyperreactivity of the central sympathetic nervous system to orthostatic stress and normal function of digital arterioles and postganglionic sympathetic nerve fibres. PMID:3109573

Olsen, N; Petring, O U; Rossing, N

1987-01-01

147

How to classify reflexive Gorenstein cones  

NASA Astrophysics Data System (ADS)

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

Skarke, Harald

2013-10-01

148

How to Classify Reflexive Gorenstein Cones  

E-print Network

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

Skarke, Harald

2012-01-01

149

How to Classify Reflexive Gorenstein Cones  

E-print Network

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

Harald Skarke

2012-04-05

150

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

PubMed Central

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

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

2013-01-01

151

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

PubMed

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

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

2013-08-01

152

Nasonasal reflexes, the nasal cycle, and sneeze  

Microsoft Academic Search

The nasal mucosa is a complex tissue that interacts with its environment and effects local and systemic changes. Receptors\\u000a in the nose receive signals from stimuli, and respond locally through afferent, nociceptive, type C neurons to elicit nasonasal\\u000a reflex responses mediated via cholinergic neurons. This efferent limb leads to responses in the nose (eg, rhinorrhea, glandular\\u000a hyperplasia, hypersecretion with mucosal

James N. Baraniuk; Dennis Kim

2007-01-01

153

Photic sneeze reflex in nephropathic cystinosis.  

PubMed Central

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

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

1990-01-01

154

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

155

Ethical reflections: examining reflexivity through the narrative paradigm.  

PubMed

Being reflexive and providing these reflections for public scrutiny is often considered a key element of ethical, rigorous qualitative research. Prevalent conceptualizations of reflexivity, however, need interrogating and sharpening. We aim to contribute to this by examining reflexive practice, and in particular researchers' reflexive accounts, through the lens of the narrative paradigm. Our aim is to demonstrate that acknowledging the role of narrative reconstruction in reflexivity creates more ethical research, and that it is therefore crucial for researchers to more explicitly recognize this. Both authors present an analysis of one particular exchange between interviewer and participant. This analysis highlights that despite our best efforts at "doing reflexivity," both immediately following and when reflecting back on an interview, there are influential factors that escape our gaze. Reflections of the past are particularly imperfect. Without fully recognizing this, we are not utilizing all the tools available for ensuring honest, ethical research. PMID:21508253

Bishop, Emily C; Shepherd, Marie L

2011-09-01

156

Attention to bright surfaces enhances the pupillary light reflex.  

PubMed

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

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

2013-01-30

157

Inhibition of micturition reflex by activation of somatic afferents in posterior femoral cutaneous nerve.  

PubMed

This study determined if activation of somatic afferents in posterior femoral cutaneous nerve (PFCN) could modulate the micturition reflex recorded under isovolumetric conditions in ?-chloralose anaesthetized cats. PFCN stimulation inhibited reflex bladder activity and significantly (P <0.05) increased bladder capacity during slow infusion of saline or 0.25% acetic acid (AA). The optimal frequency for PFCN stimulation-induced bladder inhibition was between 3 and 10 Hz, and a minimal stimulation intensity of half of the threshold for inducing anal twitching was required. Bilateral pudendal nerve transection eliminated PFCN stimulation-induced anal twitching but did not change the stimulation-induced bladder inhibition, excluding the involvement of pudendal afferent or efferent axons in PFCN afferent inhibition.Mechanical or electrical stimulation on the skin surface in the PFCN dermatome also inhibited bladder activity. Prolonged (2 × 30 min) PFCN stimulation induced a post-stimulation inhibition that persists for at least 2 h. This study revealed a new cutaneous-bladder reflex activated by PFCN afferents. Although the mechanisms and physiological functions of this cutaneous-bladder reflex need to be further studied, our data raise the possibility that stimulation of PFCN afferents might be useful clinically for the treatment of overactive bladder symptoms. PMID:22869011

Tai, Changfeng; Shen, Bing; Mally, Abhijith D; Zhang, Fan; Zhao, Shouguo; Wang, Jicheng; Roppolo, James R; de Groat, William C

2012-10-01

158

Inhibition of micturition reflex by activation of somatic afferents in posterior femoral cutaneous nerve  

PubMed Central

This study determined if activation of somatic afferents in posterior femoral cutaneous nerve (PFCN) could modulate the micturition reflex recorded under isovolumetric conditions in ?-chloralose anaesthetized cats. PFCN stimulation inhibited reflex bladder activity and significantly (P < 0.05) increased bladder capacity during slow infusion of saline or 0.25% acetic acid (AA). The optimal frequency for PFCN stimulation-induced bladder inhibition was between 3 and 10 Hz, and a minimal stimulation intensity of half of the threshold for inducing anal twitching was required. Bilateral pudendal nerve transection eliminated PFCN stimulation-induced anal twitching but did not change the stimulation-induced bladder inhibition, excluding the involvement of pudendal afferent or efferent axons in PFCN afferent inhibition. Mechanical or electrical stimulation on the skin surface in the PFCN dermatome also inhibited bladder activity. Prolonged (2 × 30 min) PFCN stimulation induced a post-stimulation inhibition that persists for at least 2 h. This study revealed a new cutaneous-bladder reflex activated by PFCN afferents. Although the mechanisms and physiological functions of this cutaneous-bladder reflex need to be further studied, our data raise the possibility that stimulation of PFCN afferents might be useful clinically for the treatment of overactive bladder symptoms. PMID:22869011

Tai, Changfeng; Shen, Bing; Mally, Abhijith D; Zhang, Fan; Zhao, Shouguo; Wang, Jicheng; Roppolo, James R; de Groat, William C

2012-01-01

159

Role of Striated Sphincter Muscle in Urethral Closure under Stress Conditions: An Experimental Study  

Microsoft Academic Search

The three-component mechanism for urethral closure under stress conditions is composed of urethral tension, passive pressure transmission and reflex pressure transmission. The reflex pressure transmission is regarded as a global result of the striated muscles of the urethra and the pelvic floor. In this experimental study, the question of what peak the reflex pressure reaches and which parts of the

H. Heidler; F. Casper; J. W. Thüroff

1987-01-01

160

Bourdieu's Reflexive Sociology and "Spaces of Points of View": Whose Reflexivity, Which Perspective?  

ERIC Educational Resources Information Center

This paper considers Bourdieu's concepts of perspectivism and reflexivity, looking particularly at how he develops arguments about these in his recent work, The Weight of the World (1999) and Pascalian Meditations (2000b). We explicate Bourdieu's distinctive purposes and deployment of these terms and approaches, and discuss how this compares with…

Kenway, Jane; McLeod, Julie

2004-01-01

161

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

Microsoft Academic Search

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

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

1990-01-01

162

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

Microsoft Academic Search

Laser stimulation of the supraorbital regions evokes brain potentials (LEPs) related to trigeminal nociception. The aim of this study was to record the R2 component of the blink reflex and the corneal reflex in 20 normal subjects, comparing the scalp activity following these reflexes with the nociceptive potentials evoked by CO2 laser stimulation of supraorbital regions. Cortical and muscular reflexes

Marina de Tommaso; Giuseppe Libro; Marco Guido; Vittorio Sciruicchio; Francomichele Puca

2001-01-01

163

Ultrasonic evaluation of pupillary light reflex  

Microsoft Academic Search

Background  Evaluation of pupillary light reflex (PLR) is an important neurological test with a variety of clinical applications. Obstacles\\u000a such as severe soft tissue damage or hyphema may obstruct the visual access to the pupil, thus rendering direct PLR observation\\u000a difficult or impossible. Multipurpose ultrasonic systems, however, can overcome this problem.\\u000a \\u000a \\u000a \\u000a Methods  Using ultrasound imaging, a coronal view of the iris and

Ashot E. SargsyanDouglas; Douglas R. Hamilton; Shannon L. Melton; David Amponsah; Nathan E. Marshall; Scott A. Dulchavsky

2009-01-01

164

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

165

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

166

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

167

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

168

Assessing European futures in an age of reflexive security  

Microsoft Academic Search

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

Tom Vander Beken; Kristof Verfaillie

2010-01-01

169

ACTION CURRENT PATTERNS OF HOMOLOGOUS MUSCLE GROUPS DURING REFLEX ACTIVITY  

Microsoft Academic Search

Hypothetical induction from experimental facts supporting the theory of cerebral dominance suggested the possibility that action current records of reflex activity from the two sides of the body might indicate the dominant of the two hemispheres. This study attempts to test this hypothesis; in addition action current records were examined for evidence of any inter-relationship existing between the same reflexes

Mervin Patterson

1937-01-01

170

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

171

Electromechanical delay and reflex response in spastic cerebral palsy  

Microsoft Academic Search

Granata KP, Ikeda AJ, Abel MF. Electromechanical delay and reflex response in spastic cerebral palsy. Arch Phys Med Rehabil 2000;81:888-94. Objective: Electromechanical delay (EMD) and reflex response in patients with spastic cerebral palsy (CP) were quantified and compared with those in normally developing individuals. It was hypothesized that the increased muscle stiffness associated with spasticity must make EMD shorter than

Kevin P. Granata; Andrea J. Ikeda; Mark F. Abel

2000-01-01

172

System identification of human triceps surae stretch reflex dynamics  

Microsoft Academic Search

The interpretation of stretch-evoked reflex responses is complicated by the fact that the pattern of response will depend upon both the underlying reflex mechanisms and the time course of the stretch used to evoke the response. The objective of the present study was to use engineering systems analysis techniques to identify the dynamics of the human triceps surae (TS) stretch

R. E. Kearney; I. W. Hunter

1983-01-01

173

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

174

Cardiovascular regulation by skeletal muscle reflexes in health and disease  

PubMed Central

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

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

2011-01-01

175

Reflexivity of Discomfort in Insider-Outsider Educational Research  

ERIC Educational Resources Information Center

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

Hamdan, Amani K.

2009-01-01

176

Amelioration of Depressed Cardiopulmonary Reflex Control of Sympathetic Nerve Activity by Short-Term Exercise Training in Male Rabbits with Heart Failure  

Microsoft Academic Search

Abstract The reflex regulation of sympathetic nerve activity has been demonstrated,to be impaired in the chronic heart failure (CHF) state compared,to the normal condition. Exercise training (EX) appears to be beneficial to patients with CHF and has been shown to reduce sympathetic outflow in this disease state. We tested the hypothesis that EX corrects the reduced cardiopulmonary,(CP) reflex response to

R. U. Pliquett; K. G. Cornish; K. P. Patel; H. D. Schultz; J. D. Peuler; I. H. Zucker

2003-01-01

177

Pupil Light Reflex Produced by Glare under Mesopic Adaptation  

NASA Astrophysics Data System (ADS)

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 methodology to measure pupil diameter is required. In the present paper pupil diameter, in steady (0.5 cd/m2) and dynamic adaptation conditions, is measured. The dynamic state is originated by a transient peripheral glare source with three different illuminance levels (15, 30 and 60 lx). Ten eyes of 5 subjects (19, 36, 50, 53 and 52 years old) are considered. The measurements are made by means of a video of the pupil captured with a CCD while the sight is fixated in a chart. In the steady condition, the average pupil diameter for each subject varies between 4.8 and 7.2 mm from one subject to another. In the dynamic condition, latency time results to be independent both of the subject and of the glare level, adding evidence to the robustness of this parameter when radiation is not incident centrally.

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

178

Reflexive differential forms on singular spaces -- Geometry and Cohomology  

E-print Network

Based on a recent extension theorem for reflexive differential forms, that is, regular differential forms defined on the smooth locus of a possibly singular variety, we study the geometry and cohomology of sheaves of reflexive differentials. First, we generalise the extension theorem to holomorphic forms on locally algebraic complex spaces. We investigate the (non-)existence of reflexive pluri-differentials on singular rationally connected varieties, using a semistability analysis with respect to movable curve classes. The necessary foundational material concerning this stability notion is developed in an appendix to the paper. Moreover, we prove that Kodaira-Akizuki-Nakano vanishing for sheaves of reflexive differentials holds in certain extreme cases, and that it fails in general. Finally, topological and Hodge-theoretic properties of reflexive differentials are explored.

Greb, Daniel; Peternell, Thomas

2012-01-01

179

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

180

Convergence in reflex pathways from multiple cutaneous nerves innervating the foot depends upon the number of rhythmically active limbs during locomotion.  

PubMed

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

181

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

182

Voluntary and Reflex Influences on the Initiation of Swallowing Reflex in Man  

Microsoft Academic Search

.   The electrophysiological features of voluntarily induced and reflexive\\/spontaneous swallows were investigated. In normal\\u000a subjects, swallows were elicited by infusing water either into the mouth (1–3 ml) or directly into the oropharyngeal region\\u000a through a nasopharyngeal cannula (0.3–1 ml). For water infused orally, subjects were either requested to swallow voluntarily\\u000a or instructed to resist swallowing and maintain the horizontal head

Cumhur Ertekin; Nefati Kiylioglu; Sultan Tarlaci; A. Bulent Turman; Yaprak Secil; Ibrahim Aydogdu

2001-01-01

183

Biomechanical characterization of the stretch reflex activity as an approach to spasticity measurement and modeling-a pilot study  

Microsoft Academic Search

Spasticity is a clinical condition that may develop in people with central nervous system injuries. It is believed that spasticity results from changes in the excitability of the stretch reflex pathways manifesting clinically as a velocity dependent increase in resistance to passive movement (RTPM) and exaggerated tendon jerks. A biomechanical device was designed to provide a 90 ms torque controlled

J. de J. Salazar-Torres; A. D. Pandyan; C. I. M. Price; R. I. Davidson; M. P. Barnes; G. R. Johnson

2003-01-01

184

Analysing responses to climate change through the lens of reflexivity.  

PubMed

Sociologists are increasingly directing attention toward social responses to climate change. As is true of any new field of inquiry, theoretical frameworks guiding the research to date have room for improvement. One advance could be achieved through closer engagement with Reflexivity Theory, particularly the work of Margaret Archer, who asks just how individuals come to give attention to certain problems, and formulate responses to them. Individuals vary significantly in regard to their understanding of and concern for anthropogenic climate change, and these standpoints in turn influence commitment to mitigation and adaptation. The emergent social interactions among all such agents in turn influence the morphogenetic trajectories through which social structures will evolve, but the role of 'meta-reflexives' is particularly crucial. Identifying pathways of individual climate change reflexivity can make a valuable contribution to our understanding of the potential for and nature of collective responses. In this paper, I explore climate change reflexivity, with particular attention to climate change meta-reflexives, through a qualitative analysis of personal interviews with residents of two small communities in Alberta, Canada. Applying Reflexivity Theory to this context articulates dimensions of reflexive processing not elaborated in current theoretical treatments, including future outlook and comfort with uncertainty, among others. PMID:23240835

Davidson, Debra

2012-12-01

185

Inactivation of the interpositus nucleus blocks the conditioned response acquired by a somatosensory conditioned stimulus in rabbit eyeblink conditioning  

Microsoft Academic Search

1.Earlier studies suggest that the memory trace for the conditioned eyeblink reflex is formed and maintained in the interpositus nucleus (IPN) in the deep cerebellar nuclei when either an auditory or visual stimulus is used as a conditioned stimulus (CS).2.In the present study, the eyeblink reflex of the rabbit was conditioned to a somatosensory CS (an airpuff onto the back).3.In

Jan Wikgren; Tapani Korhonen

2001-01-01

186

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

187

Biologically based distributed control and local reflexes improve rough terrain locomotion in a hexapod robot  

Microsoft Academic Search

Distributed control and local leg reflexes enable insects to cope easily with terrain that would defeat many legged robots. An insect-like hexapod robot incorporating biologically based control effectively responded to mechanical perturbations using active and passive compliance and a local stepping reflex. An elevator reflex and a searching reflex addressed unexpected obstacles and loss of support, respectively. The robot exhibited

Kenneth S. Espenschied; Roger D. Quinn; Randall D. Beer; Hillel J. Chiel

1996-01-01

188

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

189

Writing in the Disciplines Strategies for Reflexive Writing  

E-print Network

, or form of knowledge. Even though reflexive writing might look like a story, you do have to employ. At times, personal experience can serve as a very powerful form of proof or evidence in academic writing

190

Nasal Reflexes: Implications for Exercise, Breathing, and Sex  

PubMed Central

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

Baraniuk, James N.; Merck, Samantha J.

2014-01-01

191

Reconsidering reflexivity: introducing the case for intellectual entrepreneurship.  

PubMed

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

Cutcliffe, John R

2003-01-01

192

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2012 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...

2012-04-01

193

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

194

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2013 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...

2013-04-01

195

21 CFR 890.1450 - Powered reflex hammer.  

...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...

2014-04-01

196

Response characteristics of the human torsional vestibuloocular reflex  

NASA Technical Reports Server (NTRS)

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

Peterka, Robert J.

1992-01-01

197

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

198

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

199

LEARNING REFLEXES FOR TELEOPERATED GROUND-BASED RESCUE ROBOTS  

E-print Network

This thesis presents a system for shared autonomy, where a search and rescue robot uses training data to create a "maintain balance" reflex to enable a robot to autonomously stop, back up, or change configuration to avoid falling over...

Moss, Matthew 1987-

2011-04-25

200

Stretch reflexes and joint dynamics in rheumatoid arthritis  

Microsoft Academic Search

In clinically diagnosed rheumatoid arthritis (RA), studies were conducted to investigate the reflex and passive tissue contribution\\u000a to measured increases in joint stiffness in the resting upper limb and during constant contractions of an attached muscle.\\u000a The tonic stretch reflex was induced by a servo-controlled sinusoidal stretch perturbation of the metacarpophalangeal joint\\u000a of RA patients, and age- and sex-matched controls.

Aparna Rajagopalan; John A. Burne

2010-01-01

201

The development of reflexes and behavior in the rabbit  

E-print Network

feeding, disturbance (Critchley 1968), or sleep (Vlach, Von Bermuth & Prechtl 1968), and weakens after the eyes have opened and the animal begins to rely on visual stimuli (Fox 1964, 1965). When testing for cutaneous reflexes at this time the dog may... feeding, disturbance (Critchley 1968), or sleep (Vlach, Von Bermuth & Prechtl 1968), and weakens after the eyes have opened and the animal begins to rely on visual stimuli (Fox 1964, 1965). When testing for cutaneous reflexes at this time the dog may...

Finn, Miguelita Whelan

2012-06-07

202

Hemodynamic changes associated with the diving reflex in the dog  

E-print Network

associated with bzadycardia (23, 49, 5', 68), reduction in cardiac outpu- (23, 24, 65), vasoconstriction in all tissues other than the brain and heart (23, 24, 51, 54), and a slight rise in blood pressure (24) . These reflex changes are referred... associated with bzadycardia (23, 49, 5', 68), reduction in cardiac outpu- (23, 24, 65), vasoconstriction in all tissues other than the brain and heart (23, 24, 51, 54), and a slight rise in blood pressure (24) . These reflex changes are referred...

Jones, Charla Lynn

2012-06-07

203

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

NASA Technical Reports Server (NTRS)

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

Gunn, W. J.

1973-01-01

204

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

PubMed Central

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

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

2013-01-01

205

Additive effects of threat-of-shock and picture valence on startle reflex modulation.  

PubMed

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

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

2013-01-01

206

Tonabersat (SB-220453) a novel benzopyran with anticonvulsant properties attenuates trigeminal nerve-induced neurovascular reflexes  

PubMed Central

The effects of tonabersat (SB-220453) were evaluated on trigeminal nerve ganglion stimulation-induced sensory-autonomic neurovascular reflexes in the anaesthetized cat. Comparisons were made to intravenous administration of carabersat (SB-204269), and to valproate, gabapentin and lamotrigine following intraduodenal administration. There were no effects on resting blood pressure, heart rate, carotid blood flow or carotid vascular resistance for any compound evaluated. Trigeminal nerve ganglion stimulation increased carotid blood flow by 65% and reduced vascular resistance by 41% with minimal effect on blood pressure (<10%) and no effect on heart rate. Intravenous infusion of tonabersat or carabersat (both 3.4??mol?h?1) produced time related reductions in stimulation-induced responses with a maximal inhibition (relative to control) of 30±7% (n=4), at 240?min for tonabersat and 33±4% (n=3) at 180?min for carabersat. Tonabersat (11.5??mol?h?1) produced a similar inhibitory effect (32±9%, n=4) after 120?min of infusion. Following intraduodenal administration of tonabersat, the maximal inhibition of nerve stimulation-induced responses was 55±4% at 120?min (n=4) for tonabersat 10?mg?kg?1, and 24±2% after 180?min for 1?mg?kg?1 (n=4). Intraduodenal administration of sodium valproate (10 or 100?mg?kg?1 n=4/group) had no effect on neurovascular reflexes. Maximal inhibition of nerve ganglion-stimulated reductions in carotid vascular resistance were observed at 150?min for lamotrigine (50?mg?kg?1, 52±12%, n=4) and gabapentin (100?mg?kg?1, 17±13%, n=3). Lamotrigine 10?mg?kg?1 produced 22±11% (n=3) inhibition after 180?min. These data demonstrate blockade of trigeminal parasympathetic reflexes with tonabersat, carabersat and other anticonvulsants. These agents may therefore have therapeutic benefit in conditions where this type of reflex is evident. PMID:11264249

Parsons, Andrew A; Bingham, Sharon; Raval, Pravin; Read, Simon; Thompson, Mervyn; Upton, Neil

2001-01-01

207

[Clinical characteristics of reflex sympathetic dystrophy in Aragon (Spain). A prospective study of 171 patients].  

PubMed

We followed a total of 171 patients diagnosed with Reflex Sympathetic Dystrophy (RSD). This enigmatic condition normally has a secondary origin, being trauma the unleashing cause in most cases. Psychological predisposition plays a major role in developing the clinical state, which affects lower extremities more frequently. In this series, patients were first seen during the acute "warm" phase and the final outcome was generally good after a period of treatment with non-steroidal anti-inflammatory drugs (NSAID), calcitonin and physical therapy. However, a comprehensive review of the literature revealed the heterogeneity of this condition. PMID:21794734

Bruscas Izu, Carlos; Beltrán Audera, Chesús; Jiménez Zorzo, Fernando

2010-01-01

208

Diffuse radio emission in a REFLEX cluster  

E-print Network

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

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

2005-08-10

209

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

210

Crossed reflex reversal during human locomotion.  

PubMed

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

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

2013-05-01

211

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; Narfstrom, Kristina; Pearce, Jacqueline W.; Coates, Joan R.; Dodam, John R.; Castaner, Leilani J.; Katz, Martin L.

2013-01-01

212

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

213

Modulation of spinal reflexes by pyramidal tract stimulation in an in vitro brainstem-spinal cord preparation from the hamster  

Microsoft Academic Search

Electrophysiological evidence is presented showing that the pyramidal tract (PT) of the hamster modulates spinal reflexes in an in vitro brainstem-spinal cord preparation. Three spinal reflexes were studied. Stimulation of a dorsal root (DR) while recording from a ventral root (VR) of the same spinal segment evoked two reflexes: the monosynaptic reflex, and a long latency polysynaptic reflex. Stimulation of

J. Keifer; K. Kalil

1989-01-01

214

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

PubMed Central

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

Tokuda, Keita; Nishikawa, Michimasa; Kawahara, Shigenori

2014-01-01

215

Linear time delay methods and stability analyses of the human spine. Effects of neuromuscular reflex response.  

PubMed

Linear stability methods were applied to a biomechanical model of the human musculoskeletal spine to investigate effects of reflex gain and reflex delay on stability. Equations of motion represented a dynamic 18 degrees-of-freedom rigid-body model with time-delayed reflexes. Optimal muscle activation levels were identified by minimizing metabolic power with the constraints of equilibrium and stability with zero reflex time delay. Muscle activation levels and associated muscle forces were used to find the delay margin, i.e., the maximum reflex delay for which the system was stable. Results demonstrated that stiffness due to antagonistic co-contraction necessary for stability declined with increased proportional reflex gain. Reflex delay limited the maximum acceptable proportional reflex gain, i.e., long reflex delay required smaller maximum reflex gain to avoid instability. As differential reflex gain increased, there was a small increase in acceptable reflex delay. However, differential reflex gain with values near intrinsic damping caused the delay margin to approach zero. Forward-dynamic simulations of the fully nonlinear time-delayed system verified the linear results. The linear methods accurately found the delay margin below which the nonlinear system was asymptotically stable. These methods may aid future investigations in the role of reflexes in musculoskeletal stability. PMID:18701383

Franklin, Timothy C; Granata, Kevin P; Madigan, Michael L; Hendricks, Scott L

2008-08-01

216

The role of the superior laryngeal nerve in esophageal reflexes.  

PubMed

The aim of this study was to determine the role of the superior laryngeal nerve (SLN) in the following esophageal reflexes: esophago-upper esophageal sphincter (UES) contractile reflex (EUCR), esophago-lower esophageal sphincter (LES) relaxation reflex (ELIR), secondary peristalsis, pharyngeal swallowing, and belch. Cats (N = 43) were decerebrated and instrumented to record EMG of the cricopharyngeus, thyrohyoideus, geniohyoideus, and cricothyroideus; esophageal pressure; and motility of LES. Reflexes were activated by stimulation of the esophagus via slow balloon or rapid air distension at 1 to 16 cm distal to the UES. Slow balloon distension consistently activated EUCR and ELIR from all areas of the esophagus, but the distal esophagus was more sensitive than the proximal esophagus. Transection of SLN or proximal recurrent laryngeal nerves (RLN) blocked EUCR and ELIR generated from the cervical esophagus. Distal RLN transection blocked EUCR from the distal cervical esophagus. Slow distension of all areas of the esophagus except the most proximal few centimeters activated secondary peristalsis, and SLN transection had no effect on secondary peristalsis. Slow distension of all areas of the esophagus inconsistently activated pharyngeal swallows, and SLN transection blocked generation of pharyngeal swallows from all levels of the esophagus. Slow distension of the esophagus inconsistently activated belching, but rapid air distension consistently activated belching from all areas of the esophagus. SLN transection did not block initiation of belch but blocked one aspect of belch, i.e., inhibition of cricopharyngeus EMG. Vagotomy blocked all aspects of belch generated from all areas of esophagus and blocked all responses of all reflexes not blocked by SLN or RLN transection. In conclusion, the SLN mediates all aspects of the pharyngeal swallow, no portion of the secondary peristalsis, and the EUCR and ELIR generated from the proximal esophagus. Considering that SLN is not a motor nerve for any of these reflexes, the role of the SLN in control of these reflexes is sensory in nature only. PMID:22403790

Lang, I M; Medda, B K; Jadcherla, S; Shaker, R

2012-06-15

217

ESO Reflex: a graphical workflow engine for data reduction  

NASA Astrophysics Data System (ADS)

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

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

218

Aging attenuates the vestibulosympathetic reflex in humans  

NASA Technical Reports Server (NTRS)

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

Ray, Chester A.; Monahan, Kevin D.

2002-01-01

219

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

PubMed

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

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

2014-10-01

220

Plasticity of the human otolith-ocular reflex  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

221

Persistence of the nasotrigeminal reflex after pontomedullary transection  

PubMed Central

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

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

2012-01-01

222

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

PubMed Central

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

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

2009-01-01

223

A patient with reflex myoclonus and muscle rigidity: "jerking stiff-man syndrome".  

PubMed Central

A patient with progressive muscular rigidity associated with reflex myoclonus is described. The muscular rigidity was predominantly axial, and the myoclonic jerks affected axial and leg muscles. Jerks occurred either spontaneously, or in response to touch to the perioral region, or to stretch of head and neck muscles. Physiological investigations suggested that the myoclonus originated in the medulla and was mediated by fast-conducting pathways upwards through the brainstem and down the spinal cord. The relationship of this condition to other types of muscular rigidity with and without myoclonus is discussed. PMID:7217959

Leigh, P N; Rothwell, J C; Traub, M; Marsden, C D

1980-01-01

224

Reflexive Numbers and Berger Graphs from Calabi-Yau Spaces  

E-print Network

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

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

2005-01-14

225

ESO Reflex: A Graphical Workflow Engine for Astronomical Data Reduction  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

226

A reflexive toy-model for financial market  

NASA Astrophysics Data System (ADS)

We propose a reflexive toy model for market dynamics, based on the idea that existing reflexive loops are generated by the conviction, shared by many market operators, that a certain price follows a certain model. Their trading behaviour will therefore increase the probability that the model predictions are in fact fulfilled. We analytically write the equations generating a reflexive loop stemming from a simple linear regression model, and we show that the resulting toy model yields a peculiar intermittent behavior. The presence of two unstable fixed points is apparent from our numerical calculation and the residence-time distribution density in these points asymptotically follows an inverse-power-law tail. The exponent of this tail, as well as the scaling properties of the model output, are close to those stemming from real-price time series.

Palatella, Luigi

2010-01-01

227

Direct and consensual murine pupillary reflex metrics: establishing normative values.  

PubMed

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

2009-12-01

228

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; Stuve, Olaf

2014-01-01

229

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

230

Onset of sweating depends on the type of reflex syncope.  

PubMed

Reflex syncope is classified based on the efferent autonomic system as vasodepressant type, cardioinhibitory type and mixed type. We employed quantitative sweat testing to assess differences in sudomotor sympathetic activity in relation to the type of reflex syncope. In cardioinhibitory type sweating started in 7/9 patients after and in vasodepressor type in 11/12 patients before syncope. In mixed type sweating in 20 patients started before and in 10 after syncope. The onset of sweating correlated significantly with the onset of syncope symptoms. These results possibly reflect different onsets of emotional sweating. PMID:25009131

Struhal, Walter; Mišmaš, Antonija; Kirchmayr, Matthias; Bartl, Sigrid; Javor, Andrija; Vosko, Milan R; Ransmayr, Gerhard

2014-09-01

231

Primary reflex persistence in children with partial hearing.  

PubMed

Persistence of the asymmetrical tonic neck reflex (ATNR) was examined in children with partial hearing (aged 6-12 years). Core literacy skills were also assessed. Three groups of children were selected from three schools with special units for children with partial hearing. All children completed an upright ATNR test protocol and standardized tests of reading and spelling. Children with partial hearing had significant levels of ATNR persistence, and significant reading and spelling difficulties. The findings suggest that persistence of an early sub-cortical reflex system may be associated with some of the motor and cognitive difficulties experienced by children with partial hearing. PMID:24742313

Livingstone, Nuala; McPhillips, Martin

2014-01-01

232

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

E-print Network

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

Bonizzoni, Paola

233

Experimental and pathophysiological modulation of oesophageal afferent pathways: implications for oesophago-pharyngeal reflexes, regurgitation and symptom perception.  

E-print Network

??The work presented in this thesis concerns neurophysiology and pharmacology of the oesophageal afferent pathways involved in oesophago-pharyngeal reflexes and oesophageal nociception. Disturbances of reflexes… (more)

Szcz?sniak, Michal Marcin

2008-01-01

234

Pre- and postsynaptic modulation of monosynaptic reflex by GABAA receptors on turtle spinal cord  

PubMed Central

There is growing evidence that activation of high affinity extrasynaptic GABAA receptors in the brain, cerebellum and spinal cord substantia gelatinosa results in a tonic inhibition controlling postsynaptic excitability. The aim of the present study was to determine if GABAA receptors mediating tonic inhibition participate in the modulation of monosynaptic reflex (MSR) in the vertebrate spinal cord. Using an in vitro turtle lumbar spinal cord preparation, we show that conditioning stimulation of a dorsal root depressed the test monosynaptic reflex (MSR) at long condition–test intervals. This long duration inhibition is similar to the one seen in mammalian spinal cord and it is dependent on GABAA as it was completely blocked by 20 ?m picrotoxin (PTX) or bicuculline (BIC) or 1 ?m gabazine, simultaneously depressing the dorsal root potential (DRP) without MSR facilitation. Interestingly 100 ?m picrotoxin or BIC potentiated the MSR, depressed the DRP, and produced a long lasting motoneurone after-discharge. Furosemide, a selective antagonist of extrasynaptic GABAA receptors, affects receptor subtypes with ?4/6 subunits, and in a similar way to higher concentrations of PTX or BIC, also potentiated the MSR but did not affect the DRP, suggesting the presence of ?4/6 GABAA receptors at motoneurones. Our results suggest that (1) the turtle spinal cord has a GABAA mediated long duration inhibition similar to presynaptic inhibition observed in mammals, (2) GABAA receptors located at the motoneurones and primary afferents might produce tonic inhibition of monosynaptic reflex, and (3) GABAA receptors modulate motoneurone excitability reducing the probability of spurious and inappropriate activation. PMID:20519320

Bautista, Wendy; Aguilar, Justo; Loeza-Alcocer, Jose Emanuel; Delgado-Lezama, Rodolfo

2010-01-01

235

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

236

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

237

Algebraic Reflexivity of the set of n-Isometries on C(X,E)  

E-print Network

We prove that if the group of isometries of C(X,E) is algebraically reflexive, then the group of n-isometries is also algebraically reflexive. Here, X is a compact Hausdorff space and E is a uniformly convex Banach space such that the group of isometries of E is algebraically reflexive. As a corollary to this, we establish the algebraic reflexivity of the set of generalized bi-circular projections on C(X,E).

Abubaker, A B

2012-01-01

238

Reflexes mediated by non-impulsive afferent neurones of thoracic-coxal muscle receptor organs in the crab, Carcinus maenas  

Microsoft Academic Search

In the crab's thoracic-coxal muscle receptor (T-C MRO) system, receptor motor (Rm) input to the receptor muscle (RM) results in a variety of effects on the sensory responsiveness, and hence on the reflex output of the system.1.Repetitive stimulation of the Rm nerve with the RM under isometric conditions results in T sensory fibre depolarisation, to levels which can exceed threshold

Alberto J. Cannone; Brian M. H. Bush

1981-01-01

239

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

240

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

E-print Network

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

Zhong, Lin

241

Neuronal Mechanisms of Habituation and Dishabituation of the Gill-Withdrawal Reflex in Aplysia  

Microsoft Academic Search

The cellular mechanisms of habituation and dishabituation of the gill-withdrawal reflex in Aplysia were studied with an isolated abdominal ganglion connected to a piece of skin from the tactile receptive field of the reflex. By obtaining simultaneous intracellular recordings from both the sensory neurons and one of the main identified motor neurons, we have been able to reduce the reflex

Vincent Castellucci; Harold Pinsker; Irving Kupfermann; Eric R. Kandel

1970-01-01

242

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

243

Differential effects of stress on escape and reflex responses to nociceptive thermal stimuli in the rat  

Microsoft Academic Search

Acute stress has been shown to increase latencies of nociceptive reflexes, and this effect is considered evidence for stress-induced analgesia. However, tests for nociception that rely on motivated operant escape assess cerebral processing of pain and could be modulated independent of reflex responses. We therefore compared the effects of an acute stressor (restraint) on escape responses and lick\\/guard reflexes to

C. D King; D. P Devine; C. J Vierck; J Rodgers; R. P Yezierski

2003-01-01

244

Evaluation of Two Sympathetic Cutaneous Vasomotor Reflexes Using Laser Doppler Fluxmetry  

Microsoft Academic Search

Disturbances in sympathetic cutaneous vasomotor reflexes may be of pathogenetic importance in several microvascular problems. Laser Doppler fluxmetry (LDF) enables one to study the influence of sympathetic reflexes on skin blood flow. A matter of concern is the high variability of skin blood flow and its reactivity to sympathetic reflex test resulting in a poor reproducibility. In this study we

P. M. Netten; H. Wollersheim; P. van den Broek; T. Thien

1996-01-01

245

How Abnormal Reflexes Influence Movements in Cerebral Palsy.  

ERIC Educational Resources Information Center

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

Sellers, Jeanne Shanks

246

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

247

Gaze shift reflex in a humanoid active vision system  

Microsoft Academic Search

Full awareness of sensory surroundings requires active atten- tional and behavioral exploration. In visual animals, visual, auditory and tactile stimuli elicit gaze shifts (head and eye movements) to aid visual perception of stimuli. Such gaze shifts can either be top-down attention driven (e.g. visual search) or they can be reflex movements triggered by unexpected changes in the surroundings. Here we

Ansgar Koene; V lad Trifa; Gordon Cheng

248

Latency of the blink reflex and stimulus intensity J  

Microsoft Academic Search

The latency of the eyeblink reflex is inversely related to the intensity of the auditory or visual stimuli used to evoke it.\\u000a This is true for both mechanical and muscle action potential methods for recording the response.

Edward O. Bixler; Neil R. Bartlett; Robert W. Lansing

1967-01-01

249

Decomposition of the human electromyogramme in an inhibitory reflex  

Microsoft Academic Search

The activity of up to 4 motor units was recorded simultaneously with electrodes placed in the masseter muscle in human subjects. Mildly noxious electrical shocks were applied to the ipsilateral lip while one of the units was kept firing at a steady frequency by voluntary control. The pattern of reflex responses of each of the units was determined, and spike-triggered

T. S. Miles; K. S. Ttirker

1987-01-01

250

Pulmonary sensory and reflex responses in the mouse.  

PubMed

Mouse model research is proliferating because of its readiness for genetic manipulation. Little is known about pulmonary vagal afferents in mice, however. The purpose of this study was to determine whether their pulmonary afferents are similar to those in large animals. Single-unit activity was recorded in the cervical vagus nerve of anesthetized, open-chest, and mechanically ventilated mice. We evaluated airway sensory activity in 153 single units; 141 were mechanosensitive, with 134 inflation receptors and 7 deflation receptors. The remaining 12 receptors were chemosensitive and mechanically insensitive, showing low basal firing frequency and behaving like C-fiber or high-threshold Adelta-receptors. In separate studies, phrenic activity was recorded as an index of respiratory drive to assess pulmonary reflexes. Lung inflation produced a typical Hering-Breuer reflex, and intravenous injection of phenylbiguanide produced the typical chemoreflex resulting in apnea, bradycardia, and hypotension. These reflexes were blocked by bilateral vagotomy. We conclude that mice possess a similar set of airway sensors and pulmonary reflexes as typically found in larger animals. PMID:16675617

Zhang, J W; Walker, J F; Guardiola, J; Yu, J

2006-09-01

251

Position dependence of stretch reflex dynamics at the human ankle  

Microsoft Academic Search

The purpose of this study was to examine the effect of ankle position on the human ankle stretch reflexes during tonically-maintained contractions over most of the range of motion. The ankle was placed at randomly selected mean positions. Target levels of triceps surae (TS) or tibialis anterior (TA) tonic contractions were generated while the ankle was displaced by small amplitude,

P. L. Weiss; R. E. Kearney; I. W. Hunter

1986-01-01

252

Maturation of the human medial efferent reflex revisited  

PubMed Central

Past work applying otoacoustic emissions to gauge maturational status of the medial olivocochlear (MOC) reflex in human newborns has produced mixed results. The present study revisits the question while considering the dual nature of the 2f1 – f2 distortion product otoacoustic emission (DPOAE) and expanding measures of medial efferent function. Subjects included premature and term-born neonates, 6-month-old infants and young adults. The MOC reflex was elicited with contralateral acoustic stimulation (CAS) while shifts in amplitude and phase of the DPOAE, and its distortion and reflection components, were monitored. Overall, CAS-elicited reductions in DPOAE level did not differ among age groups. For all ages, the MOC reflex was strongest at frequencies below 1.5 kHz, and the reflection component of the DPOAE was most affected, showing maximally reduced amplitude and shallower phase slope when contralateral noise was presented. Results suggest that the MOC reflex likely reaches maturation prior to full-term birth. However, prematurely born neonates show markedly more episodes of CAS-induced DPOAE level enhancement. This may be due to more intrusive component mixing in this age group or disruptions in the formation of the MOC pathway or synapse in the most premature neonates. PMID:23363111

Abdala, Carolina; Mishra, Srikanta; Garinis, Angela

2013-01-01

253

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

254

Reflex Movements for a Virtual Human: A Biology Inspired Approach  

Microsoft Academic Search

This paper presents the results of a method to produce au- tonomous animation of virtual humans. In particular, the proposed method- ology is focused on the autonomous synthesis of non-voluntary gestures such as reflexes and subtle movements which provide a noticeable im- pression of realism and naturalness. The final goal of this technique is to produce virtual humans with a

Mario Gutiérrez; Frédéric Vexo; Daniel Thalmann

2004-01-01

255

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

256

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

257

Dissimulation and simulation as forms of religious reflexivity  

Microsoft Academic Search

This paper discusses conventional illusory enactments, largely recognised as such by those who undertake them, drawn from two Central African male initiation rites : the novices' dramatic execution on the one hand, and the purportedly painless sacrifice of the ritual's emblematic animal on the other. In doing so, it attempts to elucidate two related forms of religious reflexivity : ritual

Michael Houseman

2002-01-01

258

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

259

Hindlimb venous distention evokes a pressor reflex in decerebrated rats  

PubMed Central

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

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

2014-01-01

260

Frechet-Legendre functions and reflexive Banach spaces  

E-print Network

in a real Banach space X whose closed unit ball is denoted by BX. By a proper function f : X (-, +] we mean] extend to reflexive Banach spaces. In particular, let us state the following capstone result: Theorem 1: Primary 52A41; Secondary 46G05, 46N10, 49J50, 90C25. 1 Introduction and preliminary results We work

Borwein, Jonathan

261

Processing Reflexives and Pronouns in Picture Noun Phrase  

ERIC Educational Resources Information Center

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.…

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

2006-01-01

262

The human vertical translational vestibulo-ocular reflex. Normal and abnormal responses.  

PubMed

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

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

2009-05-01

263

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

264

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

PubMed

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

Aritomi, Shizuka; Konda, Tomoyuki; Yoshimura, Michihiro

2012-07-01

265

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

PubMed

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

Lapole, Thomas; Canon, Francis; Pérot, Chantal

2013-09-01

266

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

267

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

268

A Cartesian Reflex Assessment of Face Processing  

E-print Network

times (RTs) were mea- sured from CS onset. RTs provided a measure of the processing cost (PC by the window of a limousine en route to her wedding. He is so struck by her beauty that he is slow to react but significant cost in reaction time. Because the CRP is closely related to classical conditioning proce- dures

Massachusetts at Amherst, University of

269

Effect of viral upper respiratory tract infection on cough reflex sensitivity  

PubMed Central

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

2014-01-01

270

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

271

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

272

Possible cues driving context-specific adaptation of optocollic reflex in pigeons (Columba livia).  

PubMed

Context-specific adaptation (Shelhamer M, Clendaniel R. Neurosci Lett 332: 200-204, 2002) explains that reflexive responses can be maintained with different "calibrations" for different situations (contexts). Which context cues are crucial and how they combine to evoke context-specific adaptation is not fully understood. Gaze stabilization in birds is a nice model with which to tackle that question. Previous data showed that when pigeons (Columba livia) were hung in a harness and subjected to a frontal airstream provoking a flying posture ("flying condition"), the working range of the optokinetic head response [optocollic reflex (OCR)] extended toward higher velocities compared with the "resting condition." The present study was aimed at identifying which context cues are instrumental in recalibrating the OCR. We investigated that question by using vibrating stimuli delivered during the OCR provoked by rotating the visual surroundings at different velocities. The OCR gain increase and the boost of the fast phase velocity observed during the "flying condition" were mimicked by body vibration. On the other hand, the newly emerged relationship between the fast-phase and slow-phase velocities in the "flying condition" was mimicked by head vibration. Spinal cord lesion at the lumbosacral level decreased the effects of body vibration, whereas lesions of the lumbosacral apparatus had no effect. Our data suggest a major role of muscular proprioception in the context-specific adaptation of the stabilizing behavior, while the vestibular system could contribute to the context-specific adaptation of the orienting behavior. Participation of an efferent copy of the motor command driving the flight cannot be excluded. PMID:22049337

Gioanni, Henri; Vidal, Pierre-Paul

2012-01-01

273

The effect of mindfulness meditation on cough reflex sensitivity  

Microsoft Academic Search

Background:Chronic cough is common, and medical treatment can be ineffective. Mindfulness is a psychological intervention that aims to teach moment-to-moment non-judgemental awareness of thoughts, feelings and sensations.Method:30 healthy subjects and 30 patients with chronic cough were studied in two sequential trials. For both studies, cough reflex sensitivity to citric acid (C5) was measured on two occasions, with urge to cough

E C Young; C Brammer; E Owen; N Brown; J Lowe; C Johnson; R Calam; S Jones; A Woodcock; J A Smith

2009-01-01

274

Methods of assessing vagus nerve activity and reflexes  

Microsoft Academic Search

The methods used to assess cardiac parasympathetic (cardiovagal) activity and its effects on the heart in both humans and\\u000a animal models are reviewed. Heart rate (HR)-based methods include measurements of the HR response to blockade of muscarinic\\u000a cholinergic receptors (parasympathetic tone), beat-to-beat HR variability (HRV) (parasympathetic modulation), rate of post-exercise\\u000a HR recovery (parasympathetic reactivation), and reflex-mediated changes in HR evoked

Mark W. Chapleau; Rasna Sabharwal

2011-01-01

275

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

PubMed Central

The mammalian diving response is a remarkable behavior that overrides basic homeostatic reflexes. It is most studied in large aquatic mammals but is seen in all vertebrates. Pelagic mammals have developed several physiological adaptations to conserve intrinsic oxygen stores, but the apnea, bradycardia, and vasoconstriction is shared with those terrestrial and is neurally mediated. The adaptations of aquatic mammals are reviewed here as well as the neural control of cardiorespiratory physiology during diving in rodents. PMID:23997188

2013-01-01

276

Flexion reflex modulation during stepping in human spinal cord injury  

Microsoft Academic Search

The flexion reflex modulation pattern was investigated in nine people with a chronic spinal cord injury during stepping using\\u000a body weight support on a treadmill and manual assistance by therapists. Body weight support was provided by an upper body\\u000a harness and was adjusted for each subject to promote the best stepping pattern with the least manual assistance required by\\u000a the

Maria Knikou; Claudia A. Angeli; Christie K. Ferreira; Susan J. Harkema

2009-01-01

277

(0,2) Target Space Duality, CICYs and Reflexive Sheaves  

E-print Network

It is shown that the recently proposed target space duality for (0,2) models is not limited to models admitting a Landau-Ginzburg description. By studying some generic examples it is established for the broader class of vector bundles over complete intersections in toric varieties. Instead of sharing a common Landau-Ginzburg locus, a pair of dual models agrees in more general non-geometric phases. The mathematical tools for treating reflexive sheaves are provided, as well.

Ralph Blumenhagen

1997-10-02

278

Assessment of Baroreceptor Reflex Sensitivity by Means of Spectral Analysis  

Microsoft Academic Search

SUMMARY A method of determining baroreceptor reflex sensitivity is proposed that is based on spectral analysis of systolic pressure values and RR interval times, namely, the modulus (or gain) in the mid frequency band (0.07-0.14 Hz) between these two signals. Results using this method were highly correlated (0.94; n = 8) with results of the phenylephrine method. In addition, compared

HINDRIK W. J. ROBBE; LAMBERTUS J. M. MULDER; HEINZ RUDDEL; WOL F A. LANGEWITZ; JOHANNES B. P. VELDMAN; GUSBERTUS MULDER

279

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

280

Peripheral ?-opioid receptors attenuate the exercise pressor reflex.  

PubMed

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

Leal, Anna K; Yamauchi, Katsuya; Kim, Joyce; Ruiz-Velasco, Victor; Kaufman, Marc P

2013-10-15

281

Airway Receptors and Their Reflex Function – Invited Article  

Microsoft Academic Search

Sensory information in the lung is generated by airway receptors located throughout the respiratory tract. This information\\u000a is mainly carried by the vagus nerves and yields multiple reflex responses in disease states (cough, bronchoconstriction and\\u000a mucus secretion). Airway receptors are also essential for breathing control and lung defense. A single sensory unit contains\\u000a homogeneous or heterogeneous types of receptors, providing

J. Yu

282

Impulsive Consumption and Reflexive Thought: Nudging Ethical Consumer Behavior  

Microsoft Academic Search

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

Leonhard K. Lades

2012-01-01

283

Stretch sensitive reflexes as an adaptive mechanism for maintaining limb stability  

PubMed Central

The often studied stretch reflex is fundamental to the involuntary control of posture and movement. Nevertheless, there remains controversy regarding its functional role. Many studies have demonstrated that stretch reflexes can be modulated in a task appropriate manner. This review focuses on modulation of the long latency stretch reflex, thought to be mediated, at least in part, by supraspinal pathways. For example, this component of the stretch reflex increases in magnitude during interactions with compliant environments, relative to the sensitivity during interactions with rigid environments. This suggests that reflex sensitivity increases to augment limb stability when that stability is not provided by the environment. However, not all results support the stabilizing role of stretch reflexes. Some studies have demonstrated that involuntary responses within the time period corresponding to the long latency reflex can destabilize limb posture. We propose that this debate stems from the fact that multiple perturbation-sensitive pathways can contribute to the long latency stretch reflex and that these pathways have separate functional roles. The presented studies suggest that neural activity occurring within the period normally ascribed to the long latency stretch reflex is highly adaptable to current task demands and possibly should be considered more intelligent than “reflexive.” PMID:20434396

Shemmell, Jonathan; Krutky, Matthew A.; Perreault, Eric J.

2010-01-01

284

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

PubMed

The often studied stretch reflex is fundamental to the involuntary control of posture and movement. Nevertheless, there remains controversy regarding its functional role. Many studies have demonstrated that stretch reflexes can be modulated in a task appropriate manner. This review focuses on modulation of the long-latency stretch reflex, thought to be mediated, at least in part, by supraspinal pathways. For example, this component of the stretch reflex increases in magnitude during interactions with compliant environments, relative to its sensitivity during interactions with rigid environments. This suggests that reflex sensitivity increases to augment limb stability when that stability is not provided by the environment. However, not all results support the stabilizing role of stretch reflexes. Some studies have demonstrated that involuntary responses within the time period corresponding to the long-latency reflex can destabilize limb posture. We propose that this debate stems from the fact that multiple perturbation-sensitive pathways can contribute to the long-latency stretch reflex and that these pathways have separate functional roles. The presented studies suggest that neural activity occurring within the period normally ascribed to the long-latency stretch reflex is highly adaptable to current task demands and possibly should be considered more intelligent than "reflexive". PMID:20434396

Shemmell, Jonathan; Krutky, Matthew A; Perreault, Eric J

2010-10-01

285

Simultaneous Measurement of Noise-Activated Middle-Ear Muscle Reflex and Stimulus Frequency Otoacoustic Emissions  

PubMed Central

Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex [Guinan et al. (2003) J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higher-frequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a low-frequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probe-tone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex. PMID:16568366

Keefe, Douglas H.

2006-01-01

286

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.

Gao, Wei; Li, Jianhua

2013-01-01

287

[Effect of manipulating the risetime of an acoustic stimulus on two protective reflexes: cardiac defense and motor startle].  

PubMed

Effect of manipulating the risetime of an acoustic stimulus on two protective reflexes: cardiac defense and motor startle. The risetime is a parametric characteristic of the eliciting stimulus frequently used to differentiate among psychophysiological reflexes. The aim of the present study was to examine the effect of manipulating the risetime of an acoustic stimulus on two protective reflexes: cardiac defense and motor startle. 100 participants underwent a psychophysiological reactivity test to five presentations of an intense acoustic stimulus (105 dB white noise) under one of five risetime conditions: 0, 24, 48, 96, and 240 ms. Total energy of the stimulus was controlled by increasing the base duration of the stimulus (1000 ms) by one third of the risetime. Results showed that risetime significantly affected motor startle but not cardiac defense. Startle amplitude decreased linearly with increasing risetime after 24 ms. On the other hand, repetition of the stimulus significantly affected cardiac defense but not motor startle. These results question the traditional differentiation between startle and defense based on risetime. PMID:17296108

Ramírez Uclés, Isabel; de la Fuente Solana, Emilia Inmaculada; Martín Tamayo, Ignacio; Vila Castellar, Jaime

2006-11-01

288

Stapedial reflex and recruitment: What is the relationship with tinnitus?  

PubMed

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

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

2014-01-01

289

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

PubMed Central

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

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

2012-01-01

290

Influence of lower body negative pressure release on soleus H reflex, respiratory sensations and reflexes in human subjects.  

PubMed

Using a physiological model of acutely increasing venous return into the lungs, i.e. by applying and then releasing lower body negative pressure (LBNP) to mimic the natural stimulus of juxtapulmonary capillary (J) or pulmonary C fibre receptors, produced an immediate and significant reduction in the amplitude of the Hoffman (H) reflex by 81±4% (P=0.001) in a majority of subjects 70% (n=5). Accompanying this was a notable change in the respiratory pattern with tidal volume (V(T)) increasing in all subjects from (mean) 0.462±.038 to 0.777±.061l/min (P=0.001) and the respiratory rate (F(R)) in 40% from 14±1 to 24±0.8 breaths/min. A feeling of pressure in throat, upper chest was reported by all and a shortness of breath-by 70% of the subjects. These were similar in nature to the respiratory sensations felt with threshold doses of intravenous lobeline, a well-established chemical stimulant of J receptors. All effects lasted for 15-20s and within a minute the parameters resumed their earlier control values. In animals, respiratory augmentation and locomotion inhibition are well-established reflexes of J receptors - this simultaneous though transitory reduction in H reflex amplitude reflecting change in the excitability of the motoneurone pool and appearance of respiratory effects, is the first demonstration in human subjects of the two reflexes appearing in response to a sudden increase in pulmonary blood flow that mimics the natural stimulus of these receptors. PMID:20619362

Anand, Ashima; Raj, Hans; Gupta, Uday A; Srivastava, Niraj

2010-09-30

291

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

PubMed Central

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

De Pascalis, Vilfredo; Russo, Emanuela

2013-01-01

292

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

293

Modulation of flexion reflex induced by hip angle changes in human spinal cord injury  

Microsoft Academic Search

The flexion reflex can be elicited via stimulation of skin, muscle, and high-threshold afferents inducing a generalized flexion\\u000a of the limb. In spinalized animal models this reflex is quite prominent and is strongly modulated by actions of hip proprioceptors.\\u000a However, analogous actions on the flexion reflex in spinal cord injured (SCI) humans have not yet been examined. In this study,

Maria Knikou; Elizabeth Kay; William Zev Rymer

2006-01-01

294

Increased H-reflex response induced by intramuscular electrical stimulation of latent myofascial trigger points  

Microsoft Academic Search

Background:Myofascial trigger points (MTrPs) present with mechanical hyperalgesia and allodynia. No electrophysiological evidence exists as to the excitability of muscle spindle afferents at myofascial trigger points MTrPs. The purpose of this current study was to explore whether an H-reflex response could be elicited from intramuscular electrical stimulation. If so, to assess the possibility of increased reflex response at MTrPs.Methods:The H-reflex

Hong-You Ge; Mariano Serrao; Ole K Andersen; Thomas Graven-Nielsen; Lars Arendt-Nielsen

2009-01-01

295

Somatosensory graviception inhibits soleus H-reflex gain in humans during walking  

Microsoft Academic Search

To investigate the effects of gravity-related somatosensory information on spinal human reflexes, the soleus H-reflex was\\u000a recorded in ten healthy subjects walking on a treadmill at 2.0 km\\/h on land and in water. The modulation pattern of the soleus\\u000a H-reflex was determined in ten different phases of the step cycle. While the subjects were walking in water, the background\\u000a electromyographic activity

Tasuku Miyoshi; Keisuke Hotta; Shin-Ichiro Yamamoto; Kimitaka Nakazawa; Masami Akai

2006-01-01

296

Jaw-jerk reflex activity in relation to various clenching tasks in man  

Microsoft Academic Search

In order to investigate whether the mandibular stretch (jaw-jerk) reflex is modulated in a task-dependent manner, jaw-jerk reflexes were elicited in eight subjects during clenching with unilateral and bilateral tooth support, respectively. The reflexes were examined in the electromyographic (EMG) activity recorded by means of surface electrodes and were elicited by means of small transient jaw displacements at a constant

F. Lobbezoo; H. W. Glas; R. Buchner; A. Bilt; F. Bosman

1993-01-01

297

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

Microsoft Academic Search

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

Sandra R. Hundza; E. Paul Zehr

2009-01-01

298

Location specificity of plantar cutaneous reflexes involving lower limb muscles in humans  

Microsoft Academic Search

It is known that cutaneous reflexes in human hand muscles show strong location-specificity dependent on the digit stimulated. We hypothesized that in lower leg muscles the cutaneous reflex following tactile sensation of the plantar surface of the foot is also organized in a location-specific manner. The purpose of the present study was to test this hypothesis. Middle latency reflexes (?70–110 ms,

Tsuyoshi Nakajima; Masanori Sakamoto; Toshiki Tazoe; Takashi Endoh; Tomoyoshi Komiyama

2006-01-01

299

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

PubMed

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

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

2014-09-01

300

Implementation of an iPhone wireless accelerometer application for the quantification of reflex response.  

PubMed

The patellar tendon reflex represents an inherent aspect of the standard neurological evaluation. The features of the reflex response provide initial perspective regarding the status of the nervous system. An iPhone wireless accelerometer application integrated with a potential energy impact pendulum attached to a reflex hammer has been successfully developed, tested, and evaluated for quantifying the patellar tendon reflex. The iPhone functions as a wireless accelerometer platform. The wide coverage range of the iPhone enables the quantification of reflex response samples in rural and remote settings. The iPhone has the capacity to transmit the reflex response acceleration waveform by wireless transmission through email. Automated post-processing of the acceleration waveform provides feature extraction of the maximum acceleration of the reflex response ascertained after evoking the patellar tendon reflex. The iPhone wireless accelerometer application demonstrated the utility of the smartphone as a biomedical device, while providing accurate and consistent quantification of the reflex response. PMID:24110773

LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren; Nishikawa, Kiisa

2013-01-01

301

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

PubMed Central

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

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

2011-01-01

302

Electrical Stimulation of Afferent Neural Pathways for Suppression of Urethral Reflexes.  

E-print Network

?? Aberrant urethral reflexes following neurological injury or disease are a major component of voiding dysfunction, preventing micturition and leading to serious medical complications. Current… (more)

Mariano, Timothy Yu

2009-01-01

303

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

304

Classical conditioned responses to absent tones  

Microsoft Academic Search

BACKGROUND: Recent evidence for a tight coupling of sensorimotor processes in trained musicians led to the question of whether this coupling extends to preattentively mediated reflexes; particularly, whether a classically conditioned response in one of the domains (auditory) is generalized to another (tactile\\/motor) on the basis of a prior association in a second-order Pavlovian paradigm. An eyeblink conditioning procedure was

Marc Bangert; Uwe Jürgens; Udo Häusler; Eckart Altenmüller

2006-01-01

305

Desensitization of the cough reflex by exercise and voluntary isocapnic hyperpnea.  

PubMed

Little is known about the effects of exercise on the sensory and cognitive aspects of coughing evoked by inhalation of tussigenic agents. The threshold for the cough reflex induced by inhalation of increasing nebulizer outputs of ultrasonically nebulized distilled water (fog), an index of cough reflex sensitivity, was assessed in twelve healthy humans in control conditions, during exercise and during voluntary isocapnic hyperpnea (VIH) at the same ventilatory level as the exercise. The intensity of the urge to cough (UTC), a cognitive component of coughing, was recorded throughout the trials on a linear scale. The relationships between inhaled fog nebulizer outputs and the correspondingly evoked UTC values, an index of the perceptual magnitude of the UTC sensitivity, were also calculated. Cough appearance was always assessed audiovisually. At an exercise level of 80% of anaerobic threshold, the median cough threshold was increased from a control value of 0.73 to 2.22 ml/min (P<0.01), i.e., cough sensitivity was downregulated. With VIH, the threshold increased from 0.73 to 2.22 ml/min (P<0.01), a similar downregulation. With exercise and VIH compared with control, mean UTC values at cough threshold were unchanged, i.e., control, 3.83 cm; exercise, 3.12 cm; VIH, 4.08 cm. The relationship of the fog nebulizer output/UTC value was linear in control conditions and logarithmic during both exercise and VIH. The perception of the magnitude of the UTC seems to be influenced by signals or sensations arising from exercising limb and thoracic muscles and/or by higher nervous (cortical) mechanisms. The results indicate that the adjustments brought into action by exercise-induced or voluntary hyperpnea exert inhibitory influences on the sensory and cognitive components of fog-induced cough. PMID:20093671

Lavorini, Federico; Fontana, Giovanni A; Chellini, Elisa; Magni, Chiara; Duranti, Roberto; Widdicombe, John

2010-05-01

306

The Central Nervous Connections Involved in the Vomiting Reflex  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

307

Increased dietary salt intake enhances the exercise pressor reflex.  

PubMed

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

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

2014-02-01

308

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

309

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

310

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

311

Bone scintigraphy in the reflex sympathetic dystrophy syndrome  

SciTech Connect

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

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

1981-02-01

312

Abnormal Control of Orbicularis Oculi Reflex Excitability in Multiple Sclerosis  

PubMed Central

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

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

2014-01-01

313

Eye-head movement coordination: vestibulo-ocular reflex suppression with head-fixed target fixation.  

PubMed

To maintain clear vision, the images on the retina must remain reasonably stable. Head movements are generally dealt with successfully by counter-rotation of the eyes induced by the combined actions of the vestibulo-ocular reflex (VOR) and the optokinetic reflex. A problem of importance relates to the value of the so-called intrinsic gain of the VOR (VORG) in man, and how this gain is modulated to provide appropriate eye movements. We have studied these problems in two situations: 1. fixation of a stationary object of the visual space while the head moves; 2. fixation of an object moving with the head. These two situations were compared to a basic condition in which no visual target was allowed in order to induce "pure" VOR. Eye movements were recorded in seated subjects during stationary sinusoidal and transient rotations around the vertical axis. Subjects were in total darkness (DARK condition) and involved in mental arithmetic. Alternatively, they were provided with a small foveal target, either fixed with respect to earth (earth-fixed target: EFT condition), or moving with them (chair-fixed-target: CFT condition). The stationary rotation experiment was used as baseline for the ensuing experiment and yielded control data in agreement with the literature. In all 3 visual conditions, typical responses to transient rotations were rigorously identical during the first 200 ms. They showed, sequentially, a 16-ms delay of the eye behind the head and a rapid increase in eye velocity during 75 to 80 ms, after which the average VORG was 0.9 +/- 0.15. During the following 50 to 100 ms, the gain remained around 0.9 in all three conditions. Beyond 200 ms, the VORG remained around 0.9 in DARK and increased slowly towards 1 or decreased towards zero in the EFT and CFT conditions, respectively. The time-course of the later events suggests that visual tracking mechanisms came into play to reduce retinal slip through smooth pursuit, and position error through saccades. Our data also show that in total darkness VORG is set to 0.9 in man. Lower values reported in the literature essentially reflect predictive properties of the vestibulo-ocular mechanism, particularly evident when the input signal is a sinewave. PMID:1670149

Vercher, J L; Gauthier, G M

314

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

PubMed Central

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

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

2014-01-01

315

Visual vestibular interaction: vestibulo-ocular reflex suppression with head-fixed target fixation.  

PubMed

In order to maintain clear vision, the images on the retina must remain reasonably stable. Head movements are generally dealt with successfully by counterrotation of the eyes induced by the combined actions of the vestibulo-ocular reflex (VOR) and the opto-kinetic reflex. We have studied how, in humans, the VOR gain (VORG) is modulated to provide appropriate eye movements in two situations: 1. fixation of a stationary object of the visual space while the head moves. This requires a visuo-vestibulo-ocular reaction to induce eye movements opposite in direction, and equal in velocity to head movements, and 2. fixation of an object moving with the head. Here, the visuo-vestibulo-ocular reaction should be totally suppressed. These two situations were compared to a basic condition in which, to induce "pure" VOR, the subjects (Ss) in darkness were not allowed a visual target. Eye movements were recorded in seated Ss during constant amplitude sinusoidal and pulse-like passive rotations applied around the vertical axis. Subjects were in total darkness (DARK condition) and performing mental arithmetic. Alternatively, they were provided with a small target, either stationary with respect to earth (earth-fixed target: EFT), or moving with them (chair-fixed-target: CFT). The sinusoidal rotation experiment was used as baseline for the ensuing experiments and yielded control data in agreement with the literature. In particular, rotation in the dark showed a VORG of 0.6. With, for example, 0.8 s passive pulse rotations, typical responses in all three visual conditions were rigorously identical during the first 150 to 180 ms. They showed a delay of about 16 ms of the eye behind the head with no significant difference between passive whole-body and passive head-alone rotations. In all conditions, once the eyes had started to move, a rapid increase in eye velocity was observed during 75 to 80 ms, after which, the average VORG was 0.9 +/- 0.15. During the following 50 to 100 ms, the gain remained around 0.9 in all three conditions. Beyond 180 ms, the VORG remained around 0.9 in DARK, increased slowly towards 1 or decreased towards zero in the EFT and CFT conditions, respectively. The time-course of these later events suggests that visual tracking mechanisms came into play to reduce retinal slip through smooth pursuit. Sinusoidal rotations, extensively used in VOR studies, do not seem to be a satisfactory stimulus to rapidly and precisely characterize VOR function, particularly in pathological cases. Our data suggest that rapid transient rotations are more appropriate. PMID:2394222

Gauthier, G M; Vercher, J L

1990-01-01

316

Method for recording spinal reflexes in mice: effects of thyrotropin-releasing hormone, DOI, tolperisone and baclofen on monosynaptic spinal reflex potentials.  

PubMed

Mice were used to record the spinal reflex potentials and to examine the effects of some drugs upon them. In anesthetized mice, laminectomy was performed in the lumbo-sacral region, and monosynaptic reflex potential (MSR) and polysynaptic reflex potential were recorded from the L5 ventral root after stimulation of the L5 dorsal root. Thyrotropin-releasing hormone (TRH) and 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI) produced transient and long-lasting increases in the MSR amplitude, respectively. Tolperisone hydrochloride and baclofen produced transient and long-lasting MSR depressions, respectively. These results show that mice can be used to record spinal reflex potentials, and that it may be possible to study the spinal cord function of mutant and knockout mice using this method. PMID:11430467

Okada, H; Honda, M; Ono, H

2001-05-01

317

Repetitive pupil light reflex: potential marker in Alzheimer's disease?  

PubMed

It was investigated whether alterations of the pupil's light reflex might reflect Alzheimer's disease (AD) pathology. Changes in the pupil's system might be expected due to AD pathology present in the oculomotor system of the Edinger-Westphal nucleus, and a cholinergic deficit caused by degeneration of the nucleus basalis Meynert. A rather new method of repetitive light stimulation was applied assessing variations in pupil size, latency, and amplitude over time. We analyzed 44 healthy controls, 42 subjects with mild cognitive impairment (MCI), and 66 AD patients. AD and MCI showed a less pronounced pupil size decrease and amplitude increase over time than controls. A higher MMSE was associated with a higher increase of relative amplitude and greater decrease of latency in AD and MCI, and absolute amplitude increase in AD alone. Pupil size increase correlated with cerebrospinal fluid markers in AD. Summarized pupil light reflex is not stable under repetitive stimulation, but changes systematically and less pronounced in AD and MCI. Thus repetitive stimulation of the pupil's response potentially indicates AD pathology. PMID:25024346

Bittner, Daniel M; Wieseler, Isabel; Wilhelm, Helmut; Riepe, Matthias W; Müller, Notger G

2014-01-01

318

Vestibulosympathetic reflex during orthostatic challenge in aging humans  

NASA Technical Reports Server (NTRS)

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

Monahan, Kevin D.; Ray, Chester A.

2002-01-01

319

Reflexive polyhedra, weights and toric Calabi-Yau fibrations  

E-print Network

During the last years we have generated a large number of data related to Calabi-Yau hypersurfaces in toric varieties which can be described by reflexive polyhedra. We classified all reflexive polyhedra in three dimensions leading to K3 hypersurfaces and have nearly completed the four dimensional case relevant to Calabi-Yau threefolds. In addition, we have analysed for many of the resulting spaces whether they allow fibration structures of the types that are relevant in the context of superstring dualities. In this survey we want to give background information both on how we obtained these data, which can be found at our web site, and on how they may be used. We give a complete exposition of our classification algorithm at a mathematical (rather than algorithmic) level. We also describe how fibration structures manifest themselves in terms of toric diagrams and how we managed to find the respective data. Both for our classification scheme and for simple descriptions of fibration structures the concept of weight systems plays an important role.

Maximilian Kreuzer; Harald Skarke

2000-01-19

320

Constructing mock catalogues for the REFLEX II galaxy cluster sample  

E-print Network

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

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

2012-01-01

321

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

PubMed

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

Steen, Marc

2013-09-01

322

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

323

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

324

Temporal facilitation of spastic stretch reflexes following human spinal cord injury  

PubMed Central

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

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

2006-01-01

325

Visual vestibular interaction: vestibulo-ocular reflex suppression with head-fixed target fixation  

Microsoft Academic Search

In order to maintain clear vision, the images on the retina must remain reasonably stable. Head movements are generally dealt with successfully by counterrotation of the eyes induced by the combined actions of the vestibulo-ocular reflex (VOR) and the opto-kinetic reflex. We have studied how, in humans, the VOR gain (VORG) is modulated to provide appropriate eye movements in two

G. M. Gauthier; J.-L. Vercher

1990-01-01

326

Effects of a new centrally acting muscle relaxant, NK433 (lanperisone hydrochloride) on spinal reflexes.  

PubMed

(-)-(R)-2-methyl-3-(1-pyrrolidinyl)-4'-trifluoromethylpropiophenone++ + monohydrochloride, lanperisone hydrochloride (NK433) administered intravenously or orally depressed the mono- and polysynaptic reflex potential, dorsal root reflex potential, flexor reflex mediated by group II afferent fibers, patellar and flexor reflexes. These effects were reduced by spinal transection. NK433 inhibited the facilitation of the flexor reflex mediated by group II afferent fibers that was induced by intrathecal administration of noradrenaline-HCl. (+)-(1R,2R)-2-methyl-3-(1-pyrrolidinyl)-1-(4-trifluoromethylphenyl)-1-pr opanol (LPS-9)-HCl, a metabolite of NK433, also inhibited the spinal reflexes. Given orally, NK433 had effects more than three times stronger and tending to be longer-lasting than those of eperisone-HCl. These results suggest that NK433 exerts a non-selective inhibition on spinal reflexes and that inhibition of the descending noradrenergic tonic facilitation within the spinal cord is involved in the mechanism of spinal reflex depression by NK433. LPS-9 could contribute to the potent activity of NK433 after oral administration. PMID:9430412

Sakitama, K; Ozawa, Y; Aoto, N; Tomita, H; Ishikawa, M

1997-10-22

327

Effectiveness of an improvement writing program according to students' reflexivity levels.  

PubMed

After designing a writing program to enhance students' reflexivity and thus improve their compositions (García & de Caso, 2002a, 2002b), the aim of the research project was to show how reflexivity levels could influence the effectiveness of this program. This writing instruction through reflexivity was carried out with 5th and 6th grade students with learning disabilities (LD) and/or low achievement (LA) during 25 sessions. One hundred participants were assigned to either the experimental group (n=49), which received specific intervention in writing and reflexivity, or the control group (n=51), which simply received the ordinary curriculum. Both groups were assessed on the productivity and quality of their writing composition as well as their attitudes, self-efficacy, and reflexivity towards writing. The results show that coherence and reflexivity improved depending on the level of reflexivity, whereas the relationship with attitudes and self-efficacy is not so clear. Thus, it seems possible to improve LD and/or LA students' compositions by taking their reflexive style into account. Depending on the students' learning style, teachers should use either one or another technique. PMID:17992957

García, Jesús Nicasio; de Caso-Fuertes, Ana M

2007-11-01

328

Development of multimodal attention in young infants: Modification of the startle reflex by attention  

Microsoft Academic Search

This study examined the effect of attention engagement to compound auditory-visual stimuli on the modification of the startle blink reflex in infants. Infants at 8, 14, 20, or 26 weeks of age were presented with interesting audiovisual stimuli. After stimulus onset, at delays defined by heart rate changes known to be associated with sustained attention or attention disengagement, blink reflexes

JOHN E. RICHARDS

2000-01-01

329

Specific modulation of the Hoffmann reflex cutaneous facilitation during a reaction-time task  

Microsoft Academic Search

The Hoffmann (H) reflex and its facilitation produced by electrical stimulation of the sural area were examined before a ballistic extension of the right foot. Modulations of the cutaneous facilitation of the H reflex (CFH) were used to assess the control exerted over the transmission of low threshold cutaneous afferents. The time-course of H and CFH changes were investigated at

C. Demairé; J. Honoré; J. Le Bizec; J. M. Coquery

1989-01-01

330

Rhythmic leg cycling modulates forearm muscle H-reflex amplitude and corticospinal tract excitability  

Microsoft Academic Search

Rhythmic arm cycling leads to suppression of H-reflexes in both leg and arm muscles, and a reduction in the excitability of corticospinal projections to the forearm flexors. It is unknown, however, whether leg cycling modulates excitability in neural projections to the arms. Here we studied the extent to which rhythmic movement of the legs alters reflex (Experiment 1) and corticospinal

E. Paul Zehr; Marc Klimstra; Elizabeth A. Johnson; Timothy J. Carroll

2007-01-01

331

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

332

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

333

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

Microsoft Academic Search

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

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

334

Age-related changes of the stretch reflex excitability in human ankle muscles  

Microsoft Academic Search

The purpose of this study was to characterize the effects of aging on the stretch reflex in the ankle muscles, and in particular to compare the effects on the ankle dorsi-flexor (tibialis anterior: TA) and the plantar-flexor (soleus: SOL). Stretch reflex responses were elicited in the TA and SOL at rest and during weak voluntary contractions in 20 elderly and

Hiroki Obata; Noritaka Kawashima; Masami Akai; Kimitaka Nakazawa; Tatsuyuki Ohtsuki

2010-01-01

335

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

ERIC Educational Resources Information Center

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

Glass, Michael R.

2014-01-01

336

Point of View and Zibun: Toward a Unified Theory of the Japanese Reflexive  

E-print Network

The predominant view of the binding facts of the Japanese reflexive zibun is that there are two types of uses; one is as a reflexive which is to be bound by the clause-mate subject, and the other one is as the so-called "logophoric" pronoun...

Yabushita, Katsuhiko

1995-01-01

337

Reflexive Polyhedra and their Applications in String and F-theory  

E-print Network

This is an informal introduction to the concept of reflexive polyhedra and some of their most important applications in perturbative and non-perturbative string physics. Following the historical development, topics like mirror symmetry, gauged linear sigma models, and the geometrical structures relevant to string and F-theory dualities are discussed. Finally some recent developments concerning the classification of reflexive polyhedra are mentioned.

Harald Skarke

2000-02-29

338

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

E-print Network

Asymmetry of Hindlimb Muscle Activity and Cutaneous Reflexes After Tendon Transfers in Kittens G. E, Ontario K7L 3E6, Canada Loeb, G. E. Asymmetry of hindlimb muscle activity and cutaneous reflexes after feedback. For the major limb muscles, the patterns are reproducible across ani- mals and resistant

Loeb, Gerald E.

339

Modulation of cutaneous reflexes from the foot during gait in Parkinson's disease.  

PubMed

Normal gait is characterized by a phase-dependent modulation of cutaneous reflexes. The role of the basal ganglia in regulating these reflexes is largely unknown. Therefore cutaneous reflex responses from the skin of the foot were studied during walking of patients with mild to moderate Parkinson's disease (PD). The reflex responses were elicited by stimulation of the sural nerve of the most affected leg. The responses were studied in the biceps femoris (BF) and tibialis anterior (TA) of both legs. The latencies, durations, and phase-dependent modulation patterns of the responses were mostly comparable with those observed in healthy subjects. However, on average the amplitude of the responses in the ipsilateral and contralateral BF was respectively 1.4- and 5-fold larger for the PD patients than that for the healthy subjects. This increase was mostly seen throughout the whole step cycle. However, in some PD patients the crossed BF responses were very large during the contralateral swing phase. In such cases the increase in crossed reflexes sometimes reflected premotoneuronal gating since it was not always due to increased background activation in that period. Fast activation of contralateral BF reflexes is known to occur in conjunction with ipsilateral perturbations when there is a threat to stability. It is concluded that cutaneous reflexes are facilitated in PD but that some of the increase in reflexes in BF may be indirectly related to unsteady gait and to perceived instability. PMID:20463195

Duysens, Jacques; Van Wezel, Bart M H; Smits-Engelsman, Bouwien

2010-07-01

340

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

341

Long-Term Changes in Purposive and Reflexive Responses to Nociceptive Stimulation Following Anterolateral Chordotomy  

Microsoft Academic Search

Macaca nemestrinamonkeys received unilateral interruption of the spinothalamic tract, producing contralateral hypal- gesia and a bilateral decrease in amplitude of the flexion reflex. These effects on operant escape and reflex re- sponses to electrocutaneous stimulation (ES) were moni- tored for months to evaluate relationships between the ex- tent of each lesion and the presence or absence of recovery from the

Charles J. Vierck; Joel D. Greenspaw; Louis A. Ritzb

1990-01-01

342

The “clinalyst” : Institutionalizing reflexive space to realize safety and flexible systematization in health care  

Microsoft Academic Search

Purpose – This paper aims to present evidence for regarding reflexive practice as the crux of patient safety in tertiary hospitals. Reflexive practice buttresses safety because it is the precondition for flexible systematization – that is, the process that involves frontline clinicians in designing, redesigning and flexibly enacting care processes. Design\\/methodology\\/approach – The paper presents an account of a collaborative

Rick Iedema; Katherine Carroll

2011-01-01

343

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

Microsoft Academic Search

OBJECTIVE: This review details the anatomy and interactions of the postural and somatosensory reflexes. We attempt to identify the important role the nervous system plays in maintaining reflex control of the spine and posture. We also review, illustrate, and discuss how the human vertebral column develops, functions, and adapts to Earth's gravity in an upright position. We identify functional characteristics

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

2005-01-01

344

Perioperative bradycardia and asystole: relationship to vasovagal syncope and the Bezold-Jarisch reflex  

Microsoft Academic Search

*Corresponding author Reflex cardiovascular depression with vasodilation and bradycardia has been variously termed vasovagal syncope, the Bezold-Jarisch reflex and neurocardiogenic syncope. The circulatory response changes from the normal maintenance of arterial pressure, to parasympathetic activ- ation and sympathetic inhibition, causing hypotension. This change is triggered by reduced cardiac venous return as well as through affective mechanisms such as pain or

S. M. Kinsella; J. P. Tuckey

2001-01-01

345

Aging impairs heart rate reflexes earlier in female than in male sprague-dawley rats  

Microsoft Academic Search

We compared heart rate reflexes in conscious male or female Sprague-Dawley rats at ages of 4, 14, or 24 months to determine whether, with advancing age, baroreflex sensitivity diminishes uniformly in both sexes. Phenylephrine or sodium nitroprusside was infused intravenously to elevate or lower systemic arterial pressure and thereby elicit reflex changes in heart rate. Ensuing blood pressure responses to

Ruben D. Buñag; Lawrence W. Davidow

1996-01-01

346

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

347

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

PubMed Central

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

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

2012-01-01

348

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

PubMed Central

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

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

2014-01-01

349

Case Marking in Reflexive Construction Accompanied by Body Part Noun: A Contrastive Study of Russian and French  

Microsoft Academic Search

This paper discusses the alternation of the reflexive and non-reflexive constructions accompanied by at least one body part NP in Russian and French, in particular those that have three semantic arguments: A (agent) MOVE B (agent's body part) TO C (place or another body part). First, positive differences in the use of reflexive constructions between Russian and French are shown

MIZUNO Akiko; FUJIMURA Itsuko

350

Variation of magnitude and timing of wrist flexor stretch reflex across the full range of voluntary activation  

Microsoft Academic Search

This paper reports an investigation of the magnitude and timing of the stretch reflex over the full range of activation of flexor carpi radialis. While it is well established that the magnitude of the reflex increases with the level of muscle activation, there have been few studies of reflex magnitude above 50% of maximum voluntary contraction (MVC) and virtually no

I. Cathers; N. O’Dwyer; P. Neilson

2004-01-01

351

Blauwblomme et al.: Multimodal Imaging of Eating Reflex Seizures Multimodal Imaging Reveals the Role of Gamma Activity in Eating  

E-print Network

Blauwblomme et al.: Multimodal Imaging of Eating Reflex Seizures 1 Multimodal Imaging Reveals the Role of Gamma Activity in Eating Reflex Seizures Running head: Multimodal Imaging of Eating Reflex Seizures Thomas Blauwblomme, MSc1 , Philippe Kahane, MD PhD1,2,3,6 , Lorella Minotti MD1

Paris-Sud XI, Université de

352

Ontogeny of embryonic behavior in Aves: V. The reflex concept in the light of embryonic behavior in birds  

Microsoft Academic Search

The doctrine that habits are post-natally acquired behavior patterns integrated from simple reflexes has been justly criticized on the ground that the early behavior of most, if not all, vertebrate animals is characterized by massive movements, rather than by separate reflexes. Hence reflexes come about by a process of differentiation from the total pattern. Coghill has attempted to account for

Z. Y. Kuo

1932-01-01

353

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

PubMed Central

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

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

2005-01-01

354

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

PubMed Central

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

2013-01-01

355

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

PubMed

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

Verma, Rajesh; Gupta, Mani

2012-01-01

356

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

NASA Technical Reports Server (NTRS)

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

Truszkowski, Walt; Hinchey, Mike; Sterritt, Roy

2005-01-01

357

Critical reflexivity in financial markets: a Hawkes process analysis  

NASA Astrophysics Data System (ADS)

We model the arrival of mid-price changes in the E-mini S&P futures contract as a self-exciting Hawkes process. Using several estimation methods, we find that the Hawkes kernel is power-law with a decay exponent close to -1.15 at short times, less than ? 103 s, and crosses over to a second power-law regime with a larger decay exponent ?-1.45 for longer times scales in the range [ 103,106 ] seconds. More importantly, we find that the Hawkes kernel integrates to unity independently of the analysed period, from 1998 to 2011. This suggests that markets are and have always been close to criticality, challenging a recent study which indicates that reflexivity (endogeneity) has increased in recent years as a result of increased automation of trading. However, we note that the scale over which market events are correlated has decreased steadily over time with the emergence of higher frequency trading.

Hardiman, Stephen J.; Bercot, Nicolas; Bouchaud, Jean-Philippe

2013-10-01

358

Modeling multistage decision processes with Reflexive Game Theory  

E-print Network

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

Tarasenko, Sergey

2012-01-01

359

Evaluating palliative care: facilitating reflexive dialogues about an ambiguous concept.  

PubMed

Palliation is a relatively new concept that is used in connection with the integral care provided to those who are unable to recover from their illness. The specific meaning of the concept has not been clearly defined. This article explores the possibilities offered by a responsive approach to evaluation that can facilitate a reflexive dialogue on this ambiguous concept. In doing so it draws on a case study of a palliative care project in a Dutch health care authority. The article begins with an overview of the characteristics of a responsive approach to evaluation and addresses interpretative, representational and practical dilemmas. It goes on to present a series of dialogues between health professionals, informal caregivers, patients and evaluators. These dialogues take the form of juxtaposed stories, transcribed conversations and interpretations. Finally, the learning experiences are summarised and the appropriateness of the responsive approach to evaluate palliative care is discussed. PMID:11760226

Abma, T A

2001-01-01

360

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

361

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

362

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

PubMed

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

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

2014-10-01

363

Local electrical stimulation: effective needling points for suppressing jaw opening reflex in rat.  

PubMed

Effects of electroacupuncture on the jaw opening reflex after tooth pulp stimulation were investigated in lightly anesthetized rats. Electroacupuncture stimulation (45 Hz, 5 msec) was delivered to 8 meridian points and 6 nonmeridian ones for 15 min so as to compare the degree of suppression elicited from each point. Significant suppressive effects on the reflex were observed in the cases of Yin-Hsiang, Ho-Ku and Shou-Sanli stimulation and these effects were antagonized by naloxone. However, stimulation of Hsia-Kuan, Chu-Chih, Neiting and Taichi, although these points were reported to suppress oro-facial or dental pain in man, scarcely produced suppressive effects. On the other hand, stimulation of some nonmeridian points produced moderate analgesic effects as gauged by the jaw opening reflex. The present study revealed that specificity of the meridian points is not absolute, but relative and that Yin-Hsiang, Ho-Ku and Shou-Sanli points were fairly effective in suppressing pulp-evoked jaw opening reflex in rat, which is presumably a noxious reflex. When the jaw opening reflex was evoked by non-pulpal stimulation, electroacupuncture was less effective on the reflex. PMID:7454385

Toda, K; Suda, H; Ichioka, M; Iriki, A

1980-10-01

364

POST-TETANIC POTENTIATION OF RESPONSE IN MONOSYNAPTIC REFLEX PATHWAYS OF THE SPINAL CORD  

PubMed Central

Following tetanic afferent stimulation of a monosynaptic reflex pathway, the transmission through that pathway of isolated reflex volleys is enhanced for some minutes. Post-tetanic potentiation is comparable in the monosynaptic reflex arcs of flexor and extensor muscles. The facilitator and inhibitor actions of monosynaptic reflex afferent fibers, as well as the transmitter action, are potentiated following tetanization. Little post-tetanic change attends reflex transmission through plurisynaptic reflex arcs. Various tests for excitability change made independently of the tetanized afferent fibers reveal none or a slight depression. Hence the potentiating influence of a tetanus is limited to subsequent action on the part of the recently tetanized fibers themselves. Increase in the size of the individual impulses comprising an afferent volley such as might occur during positive after-potential, would accommodate the requirement for a limited process and provide for increased synaptic action. The proposed association between post-tetanic potentiation and positive after-potential (i.e. hyperpolarization) is supported by the following lines of evidence:— 1. Changes in intensity and duration of potentiation with change in frequency and duration of tetanic stimulation are characteristic of, and parallel to, the changes of positive after-potential in similar circumstances. 2. Afferent impulses are increased following a tetanus, and in a fashion that parallels the course of monosynaptic reflex potentiation. Post-tetanic potentiation, as here described, and after-discharge, whatever may be its mechanism, are unrelated phenomena. PMID:15406744

Lloyd, David P. C.

1949-01-01

365

Identification of intrinsic and reflexive components of human arm dynamics during postural control.  

PubMed

In this study a new methodology to quantify reflexive feedback gains from the mechanical behavior of the human arm during posture maintenance is proposed. Disturbance experiments were carried out on human subjects using continuous random force inputs. The task instruction was 'minimize displacements', prescribing a maximum performance task. For the separation of intrinsic and reflexive components, system identification in the frequency domain is applied. From the time records of position and force, frequency response functions (FRFs) are estimated. Given a model structure and an appropriate estimate of the intrinsic component, an estimate of the reflex gains for length and velocity are obtained from the FRFs. The feedback gains vary considerably with the frequency content of the disturbance signal. The results show that reflexive dynamics are substantial for narrow-band and especially low-frequency input signals. It is likely that high reflex gains are most effective for low-frequency inputs (< 3 Hz) that do not excite the closed-loop system's eigenfrequency. Also significant negative reflex gains are estimated for near-sinusoidal inputs (> 1.5 Hz). It is concluded that this new methodology can offer interesting insights into the ability of the central nervous system to modulate reflexive feedback gains. PMID:12234629

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

2002-09-15

366

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

PubMed Central

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

Onushko, Tanya; Hyngstrom, Allison

2013-01-01

367

Facial reflex examination for assessment of trigeminal nerve involvement in pituitary fossa tumours.  

PubMed Central

Sixteen patients with pituitary fossa tumours with different intrasellar extension have been studied by facial reflex examination, a neurophysiological test for the trigemino-facial pathway. Impaired transmission along the reflex path was shown in patients with proved encroachments on the flexible walls of the cavernous sinuses, but with no tumour spread to the brain stem and facial nerve. The findings were consistent with a subclinical involvement of the first trigeminal division. Tumour removal resulted in recovery in nerve conduction. It is concluded that facial reflex examination is a valuable test for detecting cavernous sinus involvement in pituitary fossa tumours. Images PMID:2993529

Bynke, O

1985-01-01

368

Sonographic Investigation of the Rectoanal Inhibitory Reflex: A Qualitative Pilot Study in Healthy Females  

Microsoft Academic Search

\\u000a Purpose  The rectoanal inhibitory reflex has been studied using various methods, e.g., anometry and electromyography. The aim of this study was to apply ultrasound for direct visualization of the rectoanal inhibitory\\u000a reflex.\\u000a \\u000a \\u000a \\u000a Method  The rectoanal inhibitory reflex was induced in ten healthy females (age range, 21–55 years) by injection of small amounts\\u000a of water (7, 12, and 20 ml), into the rectum. The

A.-K. Örnö; K. Maršál

2006-01-01

369

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

370

Glutamatergic Neurotransmission from Melanopsin Retinal Ganglion Cells Is Required for Neonatal Photoaversion but Not Adult Pupillary Light Reflex  

PubMed Central

Melanopsin-expressing retinal ganglion cells (mRGCs) in the eye play an important role in many light-activated non-image-forming functions including neonatal photoaversion and the adult pupillary light reflex (PLR). MRGCs rely on glutamate and possibly PACAP (pituitary adenylate cyclase-activating polypeptide) to relay visual signals to the brain. However, the role of these neurotransmitters for individual non-image-forming responses remains poorly understood. To clarify the role of glutamatergic signaling from mRGCs in neonatal aversion to light and in adult PLR, we conditionally deleted vesicular glutamate transporter (VGLUT2) selectively from mRGCs in mice. We found that deletion of VGLUT2 in mRGCs abolished negative phototaxis and light-induced distress vocalizations in neonatal mice, underscoring a necessary role for glutamatergic signaling. In adult mice, loss of VGLUT2 in mRGCs resulted in a slow and an incomplete PLR. We conclude that glutamatergic neurotransmission from mRGCs is required for neonatal photoaversion but is complemented by another non-glutamatergic signaling mechanism for the pupillary light reflex in adult mice. We speculate that this complementary signaling might be due to PACAP neurotransmission from mRGCs. PMID:24391855

Delwig, Anton; Majumdar, Sriparna; Ahern, Kelly; LaVail, Matthew M.; Edwards, Robert; Hnasko, Thomas S.; Copenhagen, David R.

2013-01-01

371

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 (less than 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

Leigh, R. John; Brandt, Thomas

1992-01-01

372

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

373

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...

374

Attenuation of the oculocardiac reflex after topically applied lignocaine during surgery for strabismus in children.  

PubMed

The effect of topical lignocaine applied to the eye muscles, on the incidence of the oculocardiac reflex during squint surgery of the medial rectus was investigated in 56 healthy children aged between 3-14 years. Three groups were studied. One (n = 16): stimulation of the reflex without lignocaine; 2 (n = 10): stimulation of the reflex after topical administration of 1 mg kg-1 lignocaine 2% to the medial part of the eye after induction of anaesthesia; 3 (n = 30): stimulation of the oculocardiac reflex without, and after a 5 min interval under the influence of lignocaine. Topical administered lignocaine significantly attenuated the OCR (105 vs. 68 bpm group II vs. group 1:82 vs. 63 bpm in group III). Severe bradycardiac rhythm disturbances, in particular cardiac stand-still, were not observed after lignocaine had been applied. Systemic side effects of lignocaine were not seen. PMID:8829929

Ruta, U; Möllhoff, T; Markodimitrakis, H; Brodner, G

1996-01-01

375

Voluntary and visual control of the vestibuloocular reflex after cerebral hemidecortication.  

PubMed

Horizontal vestibuloocular reflex (VOR) function was studied in five patients after cerebral hemidecortication. In darkness, VOR gain contralateral to the decorticate hemisphere was slightly higher than ipsilateral gain. Voluntary modulation of the reflex by attempted fixation of imaginary targets in darkness increased this VOR asymmetry. Voluntary cancellation of the ipsilateral VOR was better than cancellation of the contralateral VOR. Voluntary enhancement of the contralateral VOR was better than enhancement of the ipsilateral VOR. Visual control of the reflex while viewing foveal targets further increased the VOR asymmetry. Defective visual modulation corresponded to paresis of ipsilateral smooth pursuit. Abnormal voluntary responses in darkness indicate that cerebral control of the reflex can be independent of the pursuit system. The hemispheres may use a corollary discharge of eye position in the orbit and a head velocity signal to direct smooth eye movements toward the perceived location of objects. One hemisphere regulates ipsilateral smooth eye movements that achieve voluntary and visual control of the VOR. PMID:7283402

Sharpe, J A; Lo, A W

1981-08-01

376

System identification of the vestibular ocular reflex via visual and vestibular co-stimulation  

E-print Network

The study of eye motions involved in the vestibular ocular reflex (VOR) is a key tool for understanding the performance of the vestibular system and for the diagnosis of dysfunction. Limitations in experimental equipment ...

Tangorra, James Louis, 1967-

2003-01-01

377

Adaptive Effects Of Virtual Interfaces: Vestibulo-Ocular Reflex and Simulator Sickness.  

National Technical Information Service (NTIS)

Current virtual interfaces imperfectly simulate the motion dynamics of the real world. Conflicting visual and vestibular cues of self-motion are believed to result in vestibulo-ocular reflex (VOR) adaptations and simulator sickness, which raises health an...

M. H. Draper

1998-01-01

378

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

E-print Network

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

Golden, Adam J

2004-01-01

379

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

E-print Network

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

Bernert, Julia M

1987-01-01

380

Emotional qualities of odors and their influence on the startle reflex in humans.  

PubMed

Recent human and animal research suggests that the startle reflex might serve as a psychophysiological indicator of the emotional valence of foreground stimulation. The present experiment was designed to evaluate the emotional effects of positive and negative odorant stimuli. We examined the effects of continuous hydrogen sulphide (H2S) and vanillin stimulation on the magnitude of the acoustic startle reflex (measured at the M. orbicularis oculi) and on ratings of subjective valence in 16 healthy subjects. In accordance with the view that odors have emotional qualities, we found that H2S, a presumed negative foreground stimulus, significantly enhanced the startle-reflex amplitude relative to neutral air stimulation, whereas vanillin, a positive foreground stimulus, tended to reduce the reflex amplitude compared with neutral air stimulation. Both odorant stimuli were rated as equally intense by the subjects, and heart rate and electrodermal activity were not affected differentially by the two odorants. PMID:8146248

Miltner, W; Matjak, M; Braun, C; Diekmann, H; Brody, S

1994-01-01

381

Muscle Stiffness and Spinal Stretch Reflex Sensitivity in the Triceps Surae  

PubMed Central

Context: Greater musculotendinous stiffness may enhance spinal stretch reflex sensitivity by improving mechanical coupling of the muscle spindle and the stretch stimulus. This heightened sensitivity would correspond with a shorter latency and higher-amplitude reflex response, potentially enhancing joint stability. Objective: To compare spinal stretch reflex latency and amplitude across groups that differed in musculotendinous stiffness. Design: Static group comparisons. Setting: Research laboratory. Patients or Other Participants: Forty physically active individuals (20 men, 20 women). Intervention(s): We verified a sex difference in musculotendinous stiffness and compared spinal stretch reflex latency and amplitude in high-stiffness (men) and low-stiffness (women) groups. We also evaluated relationships between musculotendinous stiffness and spinal stretch reflex latency and amplitude, respectively. Main Outcome Measure(s): Triceps surae musculotendinous stiffness and soleus spinal stretch reflex latency and amplitude were assessed at 30% of a maximal voluntary isometric plantar-flexion contraction. Results: The high-stiffness group demonstrated significantly greater stiffness (137.41 ± 26.99 N/cm) than the low-stiffness group did (91.06 ± 20.10 N/cm). However, reflex latency (high stiffness = 50.11 ± 2.07 milliseconds, low stiffness = 48.26 ± 2.40 milliseconds) and amplitude (high stiffness = 0.28% ± 0.12% maximum motor response, low stiffness = 0.31% ± 0.16% maximum motor response) did not differ significantly across stiffness groups. Neither reflex latency (r = .053, P = .746) nor amplitude (r = .073, P = .653) was related significantly to musculotendinous stiffness. Conclusions: A moderate level of pretension (eg, 30%) likely eliminates series elastic slack; thus, a greater change in force per unit-of-length change (ie, heightened stiffness) would have minimal effects on coupling of the muscle spindle and the stretch stimulus and, therefore, on spinal stretch reflex sensitivity. It appears unlikely that differences in musculotendinous stiffness influenced spinal stretch reflex sensitivity when initiated from a moderate level of pretension. Consequently, differences in musculotendinous stiffness did not appear to influence dynamic joint stability with respect to reflexive neuromuscular control. PMID:18335010

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

2008-01-01

382

Management of Severe Gag Reflex by An Unique Approach: Palateless Dentures  

PubMed Central

Gagging is most common protective reflex that prevents the foreign bodies from entering trachea. But some patients have abnormally active gag reflex. The purpose of this paper was to describe method of managing gagging patients , based on modified treatment approaches, starting from impression making to design of the prosthesis i.e. palateless denture, to help the patient tolerate prosthesis in his/her mouth. PMID:24298541

Jain, Anoop; V, Vijayalaxmi; Bharathi, R.M.; Patil, Veena; Alur, Jyoti

2013-01-01

383

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

384

Influence of jaw gape on EMG of jaw muscles and jaw-stretch reflexes  

Microsoft Academic Search

The influence of jaw gapes on jaw-stretch reflexes and jaw muscles activity was studied in order to test the sensitivity of human muscle spindle afferents in various jaw muscles. Twelve healthy men (mean age±S.E.M.: 25.0±1.2yr) participated in the study. Short-latency excitatory reflex responses were evoked by a custom-made stretch device with the subjects biting on a jaw-bar with their front

Kelun Wang; Frank Lobbezoo; Peter Svensson; Lars Arendt-Nielsen

2007-01-01

385

Decoupling of stretch reflex and background muscle activity during anticipatory postural adjustments in humans  

Microsoft Academic Search

We studied the evolution of stretch reflexes in relation to background electromyographic (EMG) activity in the soleus muscle\\u000a preceding the onset of voluntary arm raise movements. Our objective was to investigate if changes in reflex EMG and muscle\\u000a activity occur simultaneously and are similarly scaled in amplitude. Ten human subjects stood with each foot on pedals able\\u000a to exert short

Siddharth Vedula; Robert E. Kearney; Ross Wagner; Paul J. Stapley

2010-01-01

386

Obstacle avoidance during human walking: H-reflex modulation during motor learning  

Microsoft Academic Search

.  The goal of this study was to investigate changes of H-reflex amplitudes during a motor learning task. Subjects with reduced\\u000a vision were instructed to step over an obstacle on a treadmill as low as possible, while the soleus H-reflex was elicited.\\u000a Acoustic warning and feedback signals about performance were provided. Performance improvement was associated with a decrease\\u000a of muscle activity,

F. Hess; H. J. A. van Hedel; V. Dietz

2003-01-01

387

Identification of time-varying dynamics of the human triceps surae stretch reflex  

Microsoft Academic Search

We examined the time-varying dynamics of the human triceps surae stretch reflex before, during, and after a large stretch was imposed upon the ankle joint, during a constant voluntary contraction of 15% of maximum voluntary contraction. Stretch reflex dynamics were estimated by superimposing a small stochastic displacement on many such stretches and using an “ensemble-based” time-varying identification procedure to compute

Robert F. Kirsch; Robert E. Kearney

1993-01-01

388

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

389

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

Microsoft Academic Search

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

C. Capaday; B. Stein

390

Integrative properties of a reflex motoneuron in the brain of the crab Carcinus maenas  

Microsoft Academic Search

1.A proximal portion of the reflex eye-withdrawal motoneuron in the crab brain (Carcinus maenas) does not conduct spike potentials but acts instead as an integrating sink for signals coming into it from smaller side branches.2.Stimulation of the primary sensory input to the reflex evokes an excitatory depolarization in this integrating segment. The excitatory depolarization is made up of summed spike

D. C. Sandeman

1969-01-01

391

Cough reflex and oral chemesthesis induced by capsaicin and capsiate in healthy never-smokers  

Microsoft Academic Search

BACKGROUND: Many tussive agents are components of foods, but little is known about the relationship between cough reflex and oral chemesthesis sensitivities. We investigated the relationships between cough reflex and oral chemesthesis in individuals using two transient receptor potential vanilloid 1 (TRPV1) agonists with different potencies: capsaicin and capsiate. METHODS: Twenty-eight healthy never-smokers were allocated to evaluate cough and oral

Miyako Yamasaki; Satoru Ebihara; Takae Ebihara; Shannon Freeman; Shinsuke Yamanda; Masanori Asada; Motoki Yoshida; Hiroyuki Arai

2007-01-01

392

Involvement of ERK phosphorylation in brainstem neurons in modulation of swallowing reflex in rats  

PubMed Central

In order to evaluate the neuronal mechanisms underlying functional abnormalities of swallowing in orofacial pain patients, this study investigated the effects of noxious orofacial stimulation on the swallowing reflex, phosphorylated extracellular signal-regulated kinase (pERK) and ?-aminobutyric acid (GABA) immunohistochemical features in brainstem neurons, and also analysed the effects of brainstem lesioning and of microinjection of GABA receptor agonist or antagonist into the nucleus tractus solitarii (NTS) on the swallowing reflex in anaesthetized rats. The swallowing reflex elicited by topical administration of distilled water to the pharyngolaryngeal region was inhibited after capsaicin injection into the facial (whisker pad) skin or lingual muscle. The capsaicin-induced inhibitory effect on the swallowing reflex was itself depressed after the intrathecal administration of MAPK kinase (MEK) inhibitor. No change in the capsaicin-induced inhibitory effect was observed after trigeminal spinal subnucleus caudalis lesioning, but the inhibitory effect was diminished by paratrigeminal nucleus (Pa5) lesioning. Many pERK-like immunoreactive neurons in the NTS showed GABA immunoreactivity. The local microinjection of the GABAA receptor agonist muscimol into the NTS produced a significant reduction in swallowing reflex, and the capsaicin-induced depression of the swallowing reflex was abolished by microinjection of the GABAA receptor antagonist bicuculline into the NTS. The present findings suggest that facial skin–NTS, lingual muscle–NTS and lingual muscle–Pa5–NTS pathways are involved in the modulation of swallowing reflex by facial and lingual pain, respectively, and that the activation of GABAergic NTS neurons is involved in the inhibition of the swallowing reflex following noxious stimulation of facial and intraoral structures. PMID:19124539

Tsujimura, Takanori; Kondo, Masahiro; Kitagawa, Junichi; Tsuboi, Yoshiyuki; Saito, Kimiko; Tohara, Haruka; Ueda, Koichiro; Sessle, Barry J; Iwata, Koichi

2009-01-01

393

H-reflex depression simulated by a biologically realistic motoneuron network  

Microsoft Academic Search

The H-reflex is frequently used both in the clinic as well as in research, with the purpose of providing a better understanding of the spinal cord. For repetitive stimuli (e.g. at 1 Hz) the H-reflex depresses, probably due to synaptic depression. Experimental results from the literature provided the basis for the simulations presented here. A large network of motoneurons connected

Rogerio R. L. Cisi; André F. Kohn

2007-01-01

394

Role of spinal serotonin 1 receptor subtypes in thermally and mechanically elicited nociceptive reflexes  

Microsoft Academic Search

The ability of 5-HT1A and 5-HT1B agonists to alter a spinal animal's nociceptive threshold was examined using two analgesiometric tests. In the spinal withdrawal reflex test, administration of the selective 5-HT1A agonists ipsapirone, gepirone and PAPP resulted in significant dose-dependent increases in receptive field (RF) area for withdrawal reflexes when compared to predrug baseline values, indicating an increase in nociceptive

Anne Z. Murphy; R. Maureen Murphy; Frank P. Zemlan

1992-01-01

395

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

396

Blood parameters and corneal-reflex of finishing pigs with and without lung affections observed post mortem in two abattoirs stunning with CO?.  

PubMed

In two pig abattoirs of different slaughter capacities, the stunning efficacy of CO2 on finishing pigs with and without pneumonic lesions (observed post mortem) was reflected against the corneal-reflex and blood parameters (blood pH, pCO2 and pO2) from individual finishers. Stunning duration was 120 s (abattoir A) and 90 s (abattoir B), respectively. Pneumonia in finisher pigs is frequently observed during post mortem inspection, which may raise concerns about a delay of unconsciousness because of hampered gas exchange in the lungs. The aim of this study was to examine possible pneumonia consequences for stunning efficacy under commercial conditions. For that, corneal reflex, O2 and CO2 partial pressure in the blood as well as blood pH were measured in 2650 finishers from abattoir A and 2100 from abattoir B. The partial pressure of O2 after stunning accounted to about 3 kPa, the partial pressure of CO2 was found at levels of about 24 kPa in abattoir A (after 120 s CO2 exposure) and 17.5 kPa in abattoir B (after 90 s CO2 exposure). In abattoir A, the blood pH was at 6.9, and at 7.0 in abattoir B. The corneal reflex was observed in 6.2% of pigs in abattoir A and 17.1% of pigs in abattoir B. A correlation between pneumonic lesions and blood status was not observed. However, for some individual farms, a significant correlation between pneumonia and corneal reflex was observed. PMID:22898535

Fries, R; Rindermann, G; Siegling-Vlitakis, C; Bandick, N; Bräutigam, L; Buschulte, A; Irsigler, H; Wolf, K; Hartmann, H

2013-02-01

397

Reflex sympathetic dystrophy: a retrospective epidemiological study of 168 patients.  

PubMed

This is a retrospective epidemiological study. The objective is to determine the epidemiological characteristics including the patient demographics, etiological factors, duration of symptoms, treatment modalities applied and clinical outcome of the treatment in reflex sympathetic dystrophy (RSD). Medical records of the 168 patients managed in two tertiary hospitals with the diagnosis of RSD that was made according to both IASP criteria and three-phase bone scan were reviewed. The upper limb was affected 1.5 times as commonly as the lower limb. Of the 168 cases, 10.7% were non-traumatic. In 89.3% of the patients, RSD developed after a traumatic inciting event with a predominance of fracture. In 75.6% of the patients, RSD developed due to job-related injuries. The percentage of successful clinical outcome was 72%. The percentage of the patients that did not respond to therapy was 28%. The management period is long and this causes higher therapeutic costs in addition to loss of productive effort. However, response to therapy is good. On the other hand, in approximately one third of the patients, RSD does not improve despite all therapeutic interventions. In addition to compensation costs, this potentially debilitating feature causes RSD to appear as a socioeconomic problem. PMID:17221145

Duman, Iltekin; Dincer, Umit; Taskaynatan, Mehmet Ali; Cakar, Engin; Tugcu, Ilknur; Dincer, Kemal

2007-09-01

398

Methods of assessing vagus nerve activity and reflexes.  

PubMed

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

2011-03-01

399

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

400

Construction of a model demonstrating neural pathways and reflex arcs.  

PubMed

Employment opportunities in the future will require higher skills and an understanding of mathematics and science. As a result of the growing number of careers that require solid science and mathematics training, the methods of science education are undergoing major reform. To adequately equip students for technologically advanced positions, new teaching methods must be developed that prepare tomorrow's workforce for the challenges of the 21st century. One such method is the use of models. By actively building and manipulating concrete models that represent scientific concepts, students are involved in the most basic level of Piaget's learning scheme: the sensorimotor stage. Models are useful in reaching all students at the foundational levels of learning, and further learning experiences are rapidly moved through higher learning levels. This success ensures greater comprehension and understanding compared with the traditional methods of rote memorization. We developed an exercise for the construction of an inexpensive, easy-to-build model demonstrating neural pathways and reflex arcs. Our exercise also includes many supplemental teaching tools. The exercise is designed to fulfill the need of sound physiological teaching materials for high school students. PMID:8997405

Chan, V; Pisegna, J M; Rosian, R L; DiCarlo, S E

1996-12-01

401

The human vestibulo-ocular reflex during linear locomotion  

NASA Technical Reports Server (NTRS)

During locomotion, there is a translation and compensatory rotation of the head in both the vertical and horizontal planes. During moderate to fast walking (100 m/min), vertical head translation occurs at the frequency of stepping (2 Hz) and generates peak linear acceleration of 0.37 g. Lateral head translation occurs at the stride frequency (1 Hz) and generates peak linear acceleration of 0.1 g. Peak head pitch and yaw angular velocities are approximately 17 degrees/s. The frequency and magnitude of these head movements are within the operational range of both the linear and angular vestibulo-ocular reflex (IVOR and aVOR). Vertical eye movements undergo a phase reversal from near to far targets. When viewing a far (>1 m) target, vertical eye velocity is typical of an aVOR response; that is, it is compensatory for head pitch. At close viewing distances (<1 m), vertical eye velocity is in phase with head pitch and is compensatory for vertical head translation, suggesting that the IVOR predominantly generates the eye movement response. Horizontal head movements during locomotion occur at the stride frequency of 1 Hz, where the IVOR gain is low. Horizontal eye movements are compensatory for head yaw at all viewing distances and are likely generated by the aVOR.

Moore, S. T.; Hirasaki, E.; Raphan, T.; Cohen, B.

2001-01-01

402

Ternary numbers and algebras. Reflexive numbers and Berger graphs  

E-print Network

The Calabi-Yau spaces with SU(m) holonomy can be studied by the algebraic way through the integer lattice where one can construct the Newton reflexive polyhedra or the Berger graphs. Our conjecture is that the Berger graphs can be directly related with the $n$-ary algebras. To find such algebras we study the n-ary generalization of the well-known binary norm division algebras, ${\\mathbb R}$, ${\\mathbb C}$, ${\\mathbb H}$, ${\\mathbb O}$, which helped to discover the most important "minimal" binary simple Lie groups, U(1), SU(2) and G(2). As the most important example, we consider the case $n=3$, which gives the ternary generalization of quaternions and octonions, $3^p$, $p=2,3$, respectively. The ternary generalization of quaternions is directly related to the new ternary algebra and group which are related to the natural extensions of the binary $su(3)$ algebra and SU(3) group. Using this ternary algebra we found the solution for the Berger graph: a tetrahedron.

A. Dubrovskiy; G. Volkov

2006-08-11

403

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

404

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

405

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

406

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

407

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

408

The adaptation of vestibulo-spinal reflexes as a function of spaceflight and their relationship to space motion sickness  

NASA Technical Reports Server (NTRS)

The hypothesis that exposure to prolonged free fall is a form of sensorymotor rearrangement rather than a direct change in otolith sensitivity or sensory compensation for a reduced otolith input is discussed. Data from Spacelab-1 experiment 1NS-104 are presented to support an otolith reinterpretation hypothesis. This experiment measured vestibulo-spinal reflex changes as a function of sustained free fall. Findings indicate that when a monosynaptic reflex (H-reflex), measured from the major postural muscles (soleus) is used, adaptation to space flight includes a change in how the central nervous system interprets a fall. In a normal gravity environment a sudden unexpected fall produces a potentiated H-reflex. After 7 days inflight, an equivalent fall does not potentiate the reflex. Postflight a greatly increased reflex is observed in those crewmen most susceptible to space motion sickness.

Reschke, M. F.; Anderson, D. J.; Homick, J. L.; Baker, J. T.; Wood, S. J.; Crosier, W. G.

1984-01-01

409

Triceps surae stretch reflex modulation after a mechanically evoked ankle dorsiflexion during the swing phase of human running.  

PubMed

The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s-1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion. We measured the electromyographic activity of the soleus, medial and lateral gastrocnemii just after the perturbation to evaluate the triceps surae stretch reflex. Similar perturbations were also delivered at rest. Our results showed that the stretch reflex was suppressed during the swing phase of running, except in late swing where a late reflex response was observed. At rest, all triceps surae muscles showed an early reflex response to stretch. Our findings suggest that the triceps surae short/medium-latency stretch reflex cannot be evoked during swing phase and thus cannot contribute to the control of the locomotor pattern after aperturbation during this phase. PMID:24718966

Scohier, Mikael; De Jaeger, Dominique; Schepens, Benedicte

2014-10-01

410

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

Microsoft Academic Search

A preliminary assay was made of the existence of time-space coherence patterns of fast EEG activity in the visual cortex of a Rhe- sus monkey. The primary intent of the present study was to evaluate the similarities and differences in relation to the olfactorybutb. where such eoherences have been described and have been demonstrated to be associated with behaviour. Segments

Walter J. Freeman; B VANDIJK

1987-01-01

411

The amplitude modulation of the Quadriceps H-reflex in relation to the knee joint action during walking  

Microsoft Academic Search

Previously the modulation of the quadriceps H-reflex has only been investigated in the initial part of the gait cycle, and\\u000a it was suggested that the quadriceps H-reflex modulates with relative high reflex gain at heel contact and decreases during\\u000a the subsequent part of stance (Dietz et al. 1990b). The objectives of the present study was to elaborate on the previous

Birgit Larsen; Natalie Mrachacz-Kersting; Brigitte A. Lavoie; Michael Voigt

2006-01-01

412

[Evaluation of perioperative analgesia by nociceptive flexor reflex in pigs under ketamine-azaperone-general anaesthesia].  

PubMed

The objective of the investigation was to evaluate quantitatively the analgesic efficacy of the Ketamine-Azaperone-general anesthesia during surgical procedures on pigs by nociceptive flexor reflexes (NFR). The study was performed in 30 four to five month old male pigs which were castrated. The NFR was evoked every minute over the N. ulnaris by multiple electrical stimulation consisting of five single stimuli (2 Hz). The reflex response was derived electromyographically (EMG) by surface electrodes placed over the M. deltoideus. The root-mean-square amplitude within the time interval of 80-240 ms after the last stimulus was calculated as measure for the reflex size. The threshold was fixed at 40 microV. Beside electrical NFR recording the surgical tolerance was determined by the traditional interdigital reflex and the defense reaction to defined surgical test stimuli which were incisisions in the scrotal skin, in the tunica vaginalis and in the testis, pulling off the spermatic cord, clamping and cutting off the spermatic cord and final wound disinfection. All surgical pain stimuli were performed simultaneously with the electrical stimuli. After induction of anesthesia the NFR amplitude declined from 3500 microV below the threshold of 40 microV. At 98% of the surgical stimuli without defense reaction were below the reflex threshold. At 93% with defense reactions demonstrated reflex amplitudes above the threshold. When the interdigital reflex was suppressed, 89% of the NFR values fell below the threshold of 40 microV. These findings demonstrate a good correlation of NFR-amplitudes with reactions to traditional controls of analgesia. PMID:22515026

Rintisch, Ulf; Baars, Jan; Lahrmann, Karl-Heinz

2012-01-01

413

[Developing team reflexivity as a learning and working tool for medical teams].  

PubMed

Team reflexivity is a collective activity in which team members review their previous work, and develop ideas on how to modify their work behavior in order to achieve better future results. It is an important learning tool and a key factor in explaining the varying effectiveness of teams. Team reflexivity encompasses both self-awareness and agency, and includes three main activities: reflection, planning, and adaptation. The model of briefing-debriefing cycles promotes team reflexivity. Its key elements include: Pre-action briefing--setting objectives, roles, and strategies the mission, as well as proposing adaptations based on what was previously learnt from similar procedures; Post-action debriefing--reflecting on the procedure performed and reviewing the extent to which objectives were met, and what can be learnt for future tasks. Given the widespread attention to team-based work systems and organizational learning, efforts should be made toward ntroducing team reflexivity in health administration systems. Implementation could be difficult because most teams in hospitals are short-lived action teams formed for a particular event, with limited time and opportunity to consciously reflect upon their actions. But it is precisely in these contexts that reflexive processes have the most to offer instead of the natural impulsive collective logics. Team reflexivity suggests a potential solution to the major problems of iatorgenesis--avoidable medical errors, as it forces all team members to participate in a reflexive process together. Briefing-debriefing technology was studied mainly in surgical teams and was shown to enhance team-based learning and to improve quality-related outcomes and safety. PMID:24791567

Riskin, Arieh; Bamberger, Peter

2014-01-01

414

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

415

Interaction of semicircular canal stimulation with carotid baroreceptor reflex control of heart rate  

NASA Technical Reports Server (NTRS)

The carotid-cardiac baroreflex contributes to the prediction of orthostatic tolerance; experimental attenuation of the reflex response leads to orthostatic hypotension in humans and animals. Anecdotal observations indicate that rotational head movements about the vertical axis of the body can also induce orthostatic bradycardia and hypotension through increased parasympathetic activity. We therefore measured the chronotropic response to carotid baroreceptor stimulation in 12 men during varying conditions of vestibulo-oculomotor stimulation to test the hypothesis that stimulation of the semicircular canals associated with head movements in the yaw plane inhibits cardioacceleration through a vagally mediated baroreflex. Carotid-cardiac baroreflex response was assessed by plotting R-R intervals (ms) at each of 8 neck pressure steps with their respective carotid distending pressures (mmHg). Calculated baroreflex gain (maximal slope of the stimulus-response relationship) was measured under 4 experimental conditions: 1) sinusoidal whole-body yaw rotation of the subject in the dark without visual fixation (combined vestibular-oculomotor stimulation); 2) yaw oscillation of the subject while tracking a small head-fixed light moving with the subject (vestibular stimulation without eye movements); 3) subject stationary while fixating on a small light oscillating in yaw at the same frequency, peak acceleration, and velocity as the chair (eye movements without vestibular stimulation); and 4) subject stationary in the dark (no eye or head motion). Head motion alone and with eye movement reduced baseline baroreflex responsiveness to the same stimulus by 30%. Inhibition of cardioacceleration during rotational head movements may have significant impact on functional performance in aerospace environments, particularly in high-performance aircraft pilots during high angular acceleration in aerial combat maneuvers or in astronauts upon return from spaceflight who already have attenuated baroreflex functions.

Convertino, V. A.

1998-01-01

416

Pulsatile motor output in human finger movements is not dependent on the stretch reflex.  

PubMed Central

1. Stretch perturbations were delivered during slow voluntary finger movements with the aim of exploring the role of the stretch reflex in generating the 8-10 Hz discontinuities that characterize these movements. Afferent activity from muscle spindle primary endings in the finger extensor muscles was recorded from the radial nerve, along with the EMG activity of these muscles, and kinematics of the relevant metacarpo-phalangeal joint. 2. Perturbations elicited a distinct response from the muscle spindles appearing at the recording electrode after 13 ms, and weak reflex responses from the muscle with peak values at 53 and 63 ms during flexion and extension, respectively. 3. The time relations between kinematics, spindle firing and modulations of EMG activity elicited by the perturbations were compared with those of the self-generated discontinuities. These analyses indicate that stretch reflex mechanisms cannot account for the modulations of EMG activity that give rise to successive 8-10 Hz discontinuities. 4. A comparison of the reflex responses to perturbations with the EMG modulations during self-generated movements indicates that the reflex was too weak to account for the pulsatile motor output during voluntary movements. 5. By inference it was concluded that the 8-10 Hz discontinuities during self-generated movements are probably generated by mechanisms within the central nervous system. PMID:8799909

Wessberg, J; Vallbo, A B

1996-01-01

417

Identified antennular near-field receptors trigger reflex flicking in the crayfish.  

PubMed

Near-field disturbances in the water column are known to trigger reflex antennular flicking in the crayfish Procambarus clarkii. We have identified the hydrodynamic sensors on the lateral antennular flagellum that constitute an afferent limb of this reflex and have measured the relative directionally dependent thresholds of the sensory neurons associated with these structures to hydrodynamic stimulation. Twenty-five individual standing feathered sensilla, comprising a sparse, linearly arrayed population of near-field sensors along the lateral and medial antennular flagella, were exposed to standardized pulsatile stimuli at 20 deg intervals along a 320 deg circular track. The results indicate that the sensilla are most sensitive to such stimulation in the plane of the flagellar axis. Identification and mechanical stimulation of single feathered sensilla in some preparations consistently evoked a flick reflex at maximal response latency, indicating that these sensors constitute at least one afferent limb for the reflex behavior. Experiments in which response latencies were measured following mechanical stimulation of truncated flagella, and were compared with the latencies in respective intact flagella, suggest that summation of inputs from the feathered sensillar pathways generates reflex flicking at minimal latencies. We discuss the possible central mechanisms that may underlie detection of critically important signals from this population of highly sensitive, inherently noisy sensors. PMID:22496293

Mellon, DeForest; Hamid, Omer A Abdul

2012-05-01

418

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

419

Volume expansion potentiates cardiac sympathetic afferent reflex in dogs.  

PubMed

Our previous study (27) showed that the cardiac sympathetic afferent reflex (CSAR) was enhanced in dogs with congestive heart failure. The aim of this study was to test whether blood volume expansion, which is one characteristic of congestive heart failure, potentiates the CSAR in normal dogs. Ten dogs were studied with sino-aortic denervation and bilateral cervical vagotomy. Arterial pressure, left ventricular pressure, left ventricular epicardial diameter, heart rate, and renal sympathetic nerve activity were measured. Coronary blood flow was also measured and, depending on the experimental procedure, controlled. Blood volume expansion was carried out by infusion of isosmotic dextran into a femoral vein at 40 ml/kg at a rate of 50 ml/min. CSAR was elicited by application of bradykinin (5 and 50 microg) and capsaicin (10 and 100 microg) to the epicardial surface of the left ventricle. Volume expansion increased arterial pressure, left ventricular pressure, left ventricular diameter, and coronary blood flow. Volume expansion without controlled coronary blood flow only enhanced the RSNA response to the high dose (50 microg) of epicardial bradykinin (17. 3 +/- 1.9 vs. 10.6 +/- 4.8%, P < 0.05). However, volume expansion significantly enhanced the RSNA responses to all doses of bradykinin and capsaicin when coronary blood flow was held at the prevolume expansion level. The RSNA responses to bradykinin (16. 9 +/- 4.1 vs. 5.0 +/- 1.3% for 5 microg, P < 0.05, and 28.9 +/- 3.7 vs. 10.6 +/- 4.8% for 50 microg, P < 0.05) and capsaicin (29.8 +/- 6.0 vs. 9.3 +/- 3.1% for 10 microg, P < 0.05, and 34.2 +/- 2.7 vs. 15.1 +/- 2.7% for 100 microg, P < 0.05) were significantly augmented. These results indicate that acute volume expansion potentiated the CSAR. These data suggest that enhancement of the CSAR in congestive heart failure may be mediated by the concomitant cardiac dilation, which accompanies this disease state. PMID:11158954

Wang, W; Schultz, H D; Ma, R

2001-02-01

420

Reflexive journaling on emotional research topics: ethical issues for team researchers.  

PubMed

Traditional epistemological concerns in qualitative research focus on the effects of researchers' values and emotions on choices of research topics, power relations with research participants, and the influence of researcher standpoints on data collection and analysis. However, the research process also affects the researchers' values, emotions, and standpoints. Drawing on reflexive journal entries of assistant researchers involved in emotionally demanding team research, this article explores issues of emotional fallout for research team members, the implications of hierarchical power imbalances on research teams, and the importance of providing ethical opportunities for reflexive writing about the challenges of doing emotional research. Such reflexive approaches ensure the emotional safety of research team members and foster opportunities for emancipatory consciousness among research team members. PMID:18000072

Malacrida, Claudia

2007-12-01

421

[The value of stapedius reflex examinations in patients with myasthenia gravis (author's transl)].  

PubMed

The behavior of the stapedius reflex was examined by means of the Z0-70 Madsen electroacoustic bridge in 41 patients (aged 9-73) with myasthenia gravis. A higher stapedius reflex threshold (90-130 db) at normal hearing was found in 66% of the cases. In 46.3% of the cases, an increased fatigue of the stapedius muscle was observed, as characterized by the lowering of the amplitude or the disappearance of the reflex after several successively repeated recordings. The examination of stapedius muscle fatigqu may be helpful indiagnosing early forms of myasthenia, in following the results of therapy for the disease, as well as in assessing the efficiency of antimyasthenic drugs. PMID:669994

Szmeja, Z; OBrebowski, A; Pruszewicz, A; Mularek, J

1978-06-01

422

The REFLEX Cluster Survey: Probing the Mass Distribution in the Universe  

E-print Network

We summarize some of the major results obtained so far from the REFLEX survey of X-ray clusters of galaxies, concentrating on the latest measurements of the cluster X-ray luminosity function and two-point correlation function. The REFLEX luminosity function provides the most homogeneous census of the distribution function of masses in the local Universe, representing a unique zero-redshift reference quantity for evolutionary studies. On the other hand, the observed clustering of REFLEX clusters is very well described both in amplitude and shape by the correlation function computed for a low-Omega_M CDM model. The bidimensional correlation map xi(r_p,pi) shows no stretching along the line of sight, indicating negligible spurious effects in the sample, with at the same time a clear compression of the contours as expected in the presence of coherent large-scale motions.

L. Guzzo; H. Boehringer; C. A. Collins; P. Schuecker; the REFLEX Team

2001-12-11

423

Completing multi-wavelength studies of the REFLEX-DXL sample  

NASA Astrophysics Data System (ADS)

To use massive clusters as the most sensitive probes to study the evolution of cosmic structure and to test cosmological models, it is important to control the systematics of the mass--observable relations. To meet this requirements, we constructed a morphology-unbiased and volume-limited sample with a well defined flux limit, consisting of 14 distant X-ray luminous clusters in the REFLEX survey (the REFLEX-DXL sample). The sample was observed in AO1 and AO3. We published detailed studies of 13 clusters. However, the observations of RXCJ2011.3-5725 were seriously spoiled by flares. To complete the REFLEX-DXL sample to finish the multi-wavelength studies, we request a re-observation of 36 ks for RXCJ2011.3-5725.

Zhang, Yu-Ying

2005-10-01

424

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

PubMed

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

425

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

426

Interruptions of fictive scratch motor rhythms by activation of cutaneous flexion reflex afferents in the turtle.  

PubMed

A low-spinal immobilized turtle displays a fictive scratch reflex in hindlimb muscle nerves in response to mechanical stimulation of specific regions of the shell (Robertson et al., 1985). There are 3 forms of the scratch reflex: the rostral, the pocket, and the caudal; each exhibits rhythmic activation of hindlimb motor neurons. Cutaneous stimulation of the distal hindlimb elicits a fictive flexion reflex that exhibits tonic excitation of hip protractor (flexor) motor neurons and tonic inhibition of knee extensor motor neurons (Stein et al., 1982). In the present study, we describe the motor pattern blends that resulted from transient activation of either the ipsilateral or the contralateral flexion reflex pathway during ongoing scratch motor patterns. Two types of blends were observed: (1) insertions of a flexion reflex synergy into an interrupted scratch cycle and (2) deletions of parts of a scratch cycle. Associated with each type of motor pattern blend was a permanent reset of the ongoing scratch rhythm. The sign of the reset (phase-advance or phase-delay) could be predicted for all forms of the scratch based on the location of the foot stimulus (ipsi- or contralateral) and its timing relative to the hip protractor/retractor cycle. The timing of knee extensor activity within the hip cycle is different for each form of the scratch (Robertson et al., 1985); thus, the sign of the reset cannot be predicted from the timing of the stimulus relative to the knee extensor cycle. These results indicate the importance of the hip rhythm in determining the overall timing of the scratch reflex.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2918373

Currie, S N; Stein, P S

1989-02-01

427

Frequency tuning of medial-olivocochlear-efferent acoustic reflexes in humans as functions of probe frequency  

PubMed Central

The medial-olivocochlear (MOC) acoustic reflex is thought to provide frequency-specific feedback that adjusts the gain of cochlear amplification, but little is known about how frequency specific the reflex actually is. We measured human MOC tuning through changes in stimulus frequency otoacoustic emissions (SFOAEs) from 40-dB-SPL tones at probe frequencies (fps) near 0.5, 1.0, and 4.0 kHz. MOC activity was elicited by 60-dB-SPL ipsilateral, contralateral, or bilateral tones or half-octave noise bands, with elicitor frequency (fe) varied in half-octave steps. Tone and noise elicitors produced similar results. At all probe frequencies, SFOAE changes were produced by a wide range of elicitor frequencies with elicitor frequencies near 0.7–2.0 kHz being particularly effective. MOC-induced changes in SFOAE magnitude and SFOAE phase were surprisingly different functions of fe: magnitude inhibition largest for fe close to fp, phase change largest for fe remote from fp. The metric ?SFOAE, which combines both magnitude and phase changes, provided the best match to reported (cat) MOC neural inhibition. Ipsilateral and contralateral MOC reflexes often showed dramatic differences in plots of MOC effect vs. elicitor frequency, indicating that the contralateral reflex does not give an accurate picture of ipsilateral-reflex properties. These differences in MOC effects appear to imply that ipsilateral and contralateral reflexes have different actions in the cochlea. The implication of these results for MOC function, cochlear mechanics, and the production of SFOAEs are discussed. PMID:22190630

Lilaonitkul, Watjana

2012-01-01

428

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

429

Influence of age and gender on the occurrence and presentation of reflex syncope  

Microsoft Academic Search

Background  The clinical history is the cornerstone of diagnosing patients with transient loss of consciousness (TLOC). Reflex syncope\\u000a is the most common cause of TLOC in patients across all ages. Knowledge of the variation in incidence and clinical features\\u000a of reflex syncope by age and gender provides important background information to acquire an accurate diagnosis.\\u000a \\u000a \\u000a \\u000a Methods  In a cohort of 503 patients

Jacobus J. C. M. Romme; Nynke van Dijk; Kimberly R. Boer; Lukas R. C. Dekker; Jan Stam; Johannes B. Reitsma; Wouter Wieling

2008-01-01

430

Einfluß von lokal appliziertem Lidocain auf die Ausprägung des okulokardialen Reflexes  

Microsoft Academic Search

\\u000a   \\u000a Introduction: The oculocardiac reflex causes severe bradycardic arrhythmias and is a frequent complication during surgical\\u000a manipulation at the medial rectus muscle. The purpose of this study was to evaluate the influence of lidocaine administered\\u000a topically on the muscle on the incidence of the oculocardiac reflex.\\u000a \\u000a \\u000a \\u000a Patients and methods: After obtaining informed consent, 140 patients with strabism or retinal surgery

Ulrich Ruta; Heinrich Gerding; Thomas Möllhoff

1997-01-01

431

The REFLEX Cluster Survey: Observing Strategy and First Results on Large-Scale Structure  

E-print Network

We give a general description of the optical observing strategy of the ROSAT-ESO Flux-Limited X-ray (REFLEX) cluster survey. This presently includes 460 clusters of galaxies selected from the ROSAT All-Sky Survey in the Southern hemisphere, to a flux limit of 3 10^{-12} erg s^{-1} cm^{-2}. Redshifts are now measured for 95% of this sample. Work is in progress to complete this coverage, and then extend the sample to fainter fluxes. A few highlights on the large-scale distribution of REFLEX clusters and their clustering properties are also discussed.

L. Guzzo; H. Boehringer; P. Schuecker; C. A. Collins; S. Schindler; D. M. Neumann; S. De Grandi; R. Cruddace; G. Chincarini; A. C. Edge; P. A. Shaver; W. Voges

1999-03-25

432

Technetium 99m-methylene diphosphonate bone scans in children with reflex neurovascular dystrophy  

SciTech Connect

Eleven children with reflex neurovascular dystrophy were investigated by technetium-labeled methylene diphosphonate bone scanning. Eight of 12 scans demonstrated abnormal findings, four showing diffusely decreased uptake and four diffusely increased uptake of the radionuclide in the affected site. Three scans showed normal findings initially, as did one previously abnormal scan when repeated in the asymptomatic patient 6 months later. Diffusely abnormal findings can be helpful in the diagnosis of childhood reflex neurovascular dystrophy, but a normal scan does not exclude the diagnosis.

Laxer, R.M.; Allen, R.C.; Malleson, P.N.; Morrison, R.T.; Petty, R.E.

1985-03-01

433

[Relationship of indices of cerebral blood flow and reflex manifestations in patients with cervicogenic vertebrobasilar insufficiency].  

PubMed

In 100 patients with cervicogenic vertebral basilar insufficiency of cerebral circulation was performed clinical and neurological examination, and transcranial Doppler arteries of vertebral basilar area. Found patterns that suggest the existence of links between reflex manifestations of vertebral basilar insufficiency and of cerebral blood flow. The presence of patients with abnormal reflex Rossolimo - Venderovich may indicate an early stage of cerebrovascular insufficiency in the vertebral basilar area and the preservation of autoregulation of cerebral blood flow. The presence of patients with VBI Chvostek III contrary may indicate a deepening of vertebral basilar insufficiency and failure of autoregulation of cerebral blood flow. PMID:25095690

Kozar-Hurina, O M

2013-06-01

434

Reflex modification and the detection of toxicant-induced auditory dysfunction.  

PubMed

There are numerous environmental chemicals that adversely impact sensory functioning in exposed populations. Test methods are needed that can rapidly and efficiently assess the potential of chemicals to induce sensory toxicity. Reflex modification of the startle response is a technique that provides rapid, objective and quantitative assessments of sensorimotor function. This procedure has been shown to be sensitive to a variety of neurotoxic compounds. Reflex modification can also provide independent estimates of chemical-induced alterations in both sensory and motor function. Future efforts should focus on expanding the use of this procedure in both the identification and characterization of neurotoxic chemicals. PMID:2247033

Crofton, K M

1990-01-01

435

Responses of the flexor reflex to LSD, tryptamine, 5-hydroxytryptophan, methoxamine, and d -amphetamine in acute and chronic spinal rats  

Microsoft Academic Search

The flexor reflex of acute (40–48 h after mid-thoracic spinal transection) and chronic (at least 2 months after transection) spinal rats was evoked by tetanic electrical stimulation of both hindfeet and recorded on a polygraph using a transducer connected to the left hindfoot. The flexor reflex in the chronic spinal rat was more responsive to electrical stimulation and to the

M. Nozaki; J. A. Bell; D. B. Vaupel; W. R. Martin

1977-01-01

436

Comments on Pediatric Elimination Dysfunctions: The Whorf Hypothesis, the Elimination Interview, the Guarding Reflex and Nocturnal Enuresis  

Microsoft Academic Search

Aims of study: This paper addresses pediatric elimination disorders including nocturnal enuresis from the perspectives of terminology (the Whorf hypothesis), the elimination interview, and the guarding reflex. Methods: The elimination interview and a modern model of normal voiding function, including the guarding reflex, are explained. Results: The language of voiding dysfunction influences our perception of it. Nocturnal enuresis, and all

David A. Bloom; John M. Park; Harry P. Koo

1998-01-01

437

Evaluation of chapman's neurolymphatic reflexes via applied kinesiology: a case report of low back pain and congenital intestinal abnormality  

Microsoft Academic Search

ObjectiveTo describe the applied kinesiologic evaluation of Chapman's neurolymphatic (NL) reflexes in the management of a person with an unusual congenital bowel abnormality and its role in the manifestation of low back pain. The theoretical foundations of these reflexes will be elaborated on and practical applications discussed.

Marcello Caso

2004-01-01

438

Effects of single and repeated exposure to apomorphine on the acoustic startle reflex and its inhibition by a visual prepulse  

Microsoft Academic Search

The acoustic startle reflex (ASR) is inhibited by startle-irrelevant stimuli that briefly precede reflex elicitation. This effect, prepulse inhibition (PPI), is reduced in strength for animals that have received dopamine agonists, such as apomorphine (APO). Reduction in PPI is most evident for weak masked noise prepulses, thus suggesting that APO disrupts the reception of stimuli to the extent that they

M. K. Taylor; J. R. Ison; S. B. Schwarzkopf

1995-01-01

439

While the organization and patterns of modulation of cutaneous reflexes have been shown to be quite similar  

E-print Network

motor tasks. For example in leg muscles, task dependency of cutaneous reflexes has been shown at similar), cycling vs. static contraction (Zehr et al. 2001) and stable vs. unstable standing (Burke et al. 1991). The main observation from these experiments is that cutaneous reflexes in leg muscles are very sensitive

Zehr, Paul

440

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