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1

Reflex conditioning in a spinal man.  

PubMed

A man with a completely transected spinal cord and a spastic neurogenic bladder was conditioned to void upon the presentation of an external stimulus. A classical conditioning paradigm was employed in which strong abdominal shock (unconditioned stimulus) was paired with an initially neutral mild electrical stimulation of the thigh (conditioned stimulus; CS). After the pairing trials, a reliable conditioned response of urination was elicited by the CS alone. The conditioned response did not extinguish over time, and the procedure left the bladder with clinically safe residual amounts of urine. Practical implications of the conditioning technique for the treatment of spastic neurogenic bladder conditions in spinally injured patients are discussed, as is the theoretical significance of conditioning at the reflex level in the absence of cortical involvement. PMID:153348

Ince, L P; Brucker, B S; Alba, A

1978-10-01

2

Is the Conditioned Reflex the Unit of Habit?  

Microsoft Academic Search

The conditioned reflex differs from habit, as the term is generally used, in that it lacks the relative robustness and self-subsistence of the latter, the discrepancy being probably due to a nonpsychological analysis of the psychological situation. The paper is in general a plea for the independence of psychology, and for the necessity of psychological treatment of psychological data. By

G. Humphrey

1925-01-01

3

Associative Mechanosensory Conditioning of the Proboscis Extension Reflex in Honeybees  

ERIC Educational Resources Information Center

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

Giurfa, Martin; Malun, Dagmar

2004-01-01

4

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.

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

2010-01-01

5

Role of Nucleic Acid Synthesis in the Stabilization of Conditioned Reflexes and Memory.  

National Technical Information Service (NTIS)

A study was made of the effect of the factor which selectively blocks the DNA-dependent synthesis of RNA - actinomycin 2703 - on the formation of new conditioned reflexes and the stabilization of previously formed conditioned reflexes. (Author)

F. Z. Meerson R. I. Kruglikov I. A. Kolomeitseva

1968-01-01

6

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

PubMed

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

Kyung-Sup, Chang

2010-09-01

7

[Genetically determined characteristics of conditioned reflex and locomotor activity of rats of different lines].  

PubMed

Peculiarities of conditioned instrumental food obtaining (getting) "pyrocmu" reflex development and realization of locomotor reactions (exploratory activity, motor activity, stance, gruming) of hypertensive (SHR) and Wistar rats in ordinary conditions and after strong sound signal were studied. It is shown that the dynamics of conditioned reflex development and its reproducing after experiment interruption are essentially different in two groups of animals: reflex conditioned in Wistar rats is of high level and is easily reproducible while in hypertensive animals it is transformed to the hidden (concealed) form of "incomplete" conditioned reflex-smelling at feeding rack in response to sound signal. The higher anxiety level and lower adaptability of hypertensive rats as compared with Wistar rats to the experimental conditions are confirmed by higher exploratory activity, more prolonged gruming in standard experimental conditions and long-duration immobility phase after sound signal. PMID:16958217

Kruchenko, Zh A

2006-01-01

8

Effects of H-reflex up-conditioning on GABAergic terminals on rat soleus motoneurons  

PubMed Central

To explore the role of spinal cord plasticity in motor learning, we evaluated the effects of H-reflex operant conditioning on GABAergic input to rat spinal motoneurons. Previous work indicated that down-conditioning of soleus H-reflex increases GABAergic input to soleus motoneurons. This study explored the effect of H-reflex up-conditioning on GABAergic input. Of nine rats exposed to H-reflex up-conditioning, up-conditioning was successful (H-reflex increase ? 20%) in seven and failed (change < 20%) in two. These rats and eight naive control (i.e. unconditioned) rats were injected with cholera toxin subunit B-conjugated Alexa fluor 488 into the soleus muscle to retrogradely label soleus motoneurons. Sections containing soleus motoneurons were processed for GAD67 [one of the two principal forms of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD)] with an ABC-peroxidase system. Two blinded independent raters counted and measured GABAergic terminals on these motoneurons. Unlike successful down-conditioning, which greatly increased the number of identifiable GABAergic terminals on the motoneurons, up-conditioning did not significantly change GABAergic terminal number. Successful up-conditioning did produce slight but statistically significant increases in GABAergic terminal diameter and soma coverage. These results are consistent with other data indicating that up- and down-conditioning are not mirror images of each other, but rather have different mechanisms. Although the marked changes in GABAergic terminals with down-conditioning probably contribute to H-reflex decrease, the modest changes in GABAergic terminals associated with up-conditioning may be compensatory or reactive plasticity, rather than the plasticity responsible for H-reflex increase. As a variety of spinal and supraspinal GABAergic neurons innervate motoneurons, the changes found with up-conditioning may be in terminals other than those affected in successful down-conditioning.

Pillai, Shreejith; Wang, Yu; Wolpaw, Jonathan R.; Chen, Xiang Yang

2010-01-01

9

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.

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

2013-01-01

10

Operant conditioning of a spinal reflex can improve locomotion after spinal cord injury in humans.  

PubMed

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 R; Wolpaw, Jonathan R

2013-02-01

11

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.

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

2014-01-01

12

Operant conditioning to increase ankle control or decrease reflex excitability improves reflex modulation and walking function in chronic spinal cord injury.  

PubMed

Ankle clonus is common after spinal cord injury (SCI) and is attributed to loss of supraspinally mediated inhibition of soleus stretch reflexes and maladaptive reorganization of spinal reflex pathways. The maladaptive reorganization underlying ankle clonus is associated with other abnormalities, such as coactivation and reciprocal facilitation of tibialis anterior (TA) and soleus (SOL), which contribute to impaired walking ability in individuals with motor-incomplete SCI. Operant conditioning can increase muscle activation and decrease stretch reflexes in individuals with SCI. We compared two operant conditioning-based interventions in individuals with ankle clonus and impaired walking ability due to SCI. Training included either voluntary TA activation (TA?) to enhance supraspinal drive or SOL H-reflex suppression (SOL?) to modulate reflex pathways at the spinal cord level. We measured clonus duration, plantar flexor reflex threshold angle, timed toe tapping, dorsiflexion (DF) active range of motion, lower extremity motor scores (LEMS), walking foot clearance, speed and distance, SOL H-reflex amplitude modulation as an index of reciprocal inhibition, presynaptic inhibition, low-frequency depression, and SOL-to-TA clonus coactivation ratio. TA? decreased plantar flexor reflex threshold angle (-4.33°) and DF active range-of-motion angle (-4.32°) and increased LEMS of DF (+0.8 points), total LEMS of the training leg (+2.2 points), and nontraining leg (+0.8 points), and increased walking foot clearance (+ 4.8 mm) and distance (+12.09 m). SOL? decreased SOL-to-TA coactivation ratio (-0.21), increased nontraining leg LEMS (+1.8 points), walking speed (+0.02 m/s), and distance (+6.25 m). In sum, we found increased voluntary control associated with TA? outcomes and decreased reflex excitability associated with SOL? outcomes. PMID:23468393

Manella, Kathleen J; Roach, Kathryn E; Field-Fote, Edelle C

2013-06-01

13

Japanese Adult Learners' Development of the Locality Condition on English Reflexives.  

ERIC Educational Resources Information Center

Explores the developmental patterns observed when Japanese adult learners acquire the locality condition on English reflexives. Experimental tasks were designed specifically to deal with the methodological problems of earlier research and then administered to Japanese learners of English at five proficiency levels as well as English and Japanese…

Akiyama, Yasuhiro

2002-01-01

14

Sensitization and aversive conditioning: Effects on the startle reflex and electrodermal responding  

Microsoft Academic Search

Animal data suggest that shock sensitization as well as aversive learning potentiates the acoustic startle reflex. The present\\u000a experiment tested, whether this shock sensitization also occurs in human subjects and whether it precedes aversive conditioning.\\u000a Sixty subjects viewed—prior to conditioning—a series of slides of different emotional contents including the to be conditioned\\u000a stimuli (CSs). Afterwards, the experimenter attached the shock

Alfons O. Hamm; Rudolf Stark

1993-01-01

15

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

16

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.

Thompson, Aiko K.; Wolpaw, Jonathan R.

2014-01-01

17

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

18

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...

19

H-reflex down-conditioning greatly increases the number of identifiable GABAergic interneurons in rat ventral horn  

Microsoft Academic Search

H-reflex down-conditioning increases GABAergic terminals on spinal cord motoneurons. To explore the origins of these terminals, we studied the numbers and distributions of spinal cord GABAergic interneurons. The number of identifiable GABAergic interneurons in the ventral horn was 78% greater in rats in which down-conditioning was successful than in naive rats or rats in which down-conditioning failed. No increase occurred

Yu Wang; Shreejith Pillai; Jonathan R. Wolpaw; Xiang Yang Chen

2009-01-01

20

An Analysis of Conditioned Reflexes and of the Thought Processes of the Human Brain.  

National Technical Information Service (NTIS)

The current status of research on mental mechanisms was surveyed. Three series of experiments, using models, attempting to analyze the information processes which take place in the brain during the functioning of a chain of reflexes are described. A bibli...

A. V. Napalkov N. I. Bobneva

1964-01-01

21

Long-term sound conditioning increases distortion product otoacoustic emission amplitudes and decreases olivocochlear efferent reflex strength.  

PubMed

The cochlea can be protected from acoustic trauma by moderate-level sound exposure. It is suggested that olivocochlear system may play a significant role in this protection. This study was performed to investigate distortion product otoacoustic emission (DPOAE) amplitudes changes and the efficiency of contralateral noise stimulation on DPOAE after conditioning noise exposure. Our results demonstrate that long-term conditioning can increase the DPOAE amplitudes at low frequencies (1.0-3.0 kHz) and decrease the olivocochlear efferent reflex strength at the same frequencies. The DPOAE amplitudes are partially restored to the preconditioning levels 2 weeks after conditioning; contralateral suppression also returns to the preconditioning levels. These results suggest that the enhancement of DPOAE amplitudes might be due to a decrease in olivocochlear efferent reflex strength. PMID:17589320

Peng, Jian-Hua; Tao, Ze-Zhang; Huang, Zhi-Wu

2007-07-16

22

H-Reflex Down-Conditioning Greatly Increases the Number of Identifiable Gabaergic Interneurons in Rat Ventral Horn  

PubMed Central

H-reflex down-conditioning increases GABAergic terminals on spinal cord motoneurons. To explore the origins of these terminals, we studied the numbers and distributions of spinal cord GABAergic interneurons. The number of identifiable GABAergic interneurons in the ventral horn was 78% greater in rats in which down-conditioning was successful than in naive rats or rats in which down-conditioning failed. No increase occurred in other spinal lamina or on the contralateral side. This finding supports the hypothesis that the corticospinal tract influence that induces the motoneuron plasticity underlying down-conditioning reaches the motoneuron through GABAergic interneurons in the ventral horn.

Wang, Yu; Pillai, Shreejith; Wolpaw, Jonathan R.; Chen, Xiang Yang

2010-01-01

23

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.

Futagi, Yasuyuki; Toribe, Yasuhisa; Suzuki, Yasuhiro

2012-01-01

24

Knee Jerk Reflex (Patellar Reflex)  

NSDL National Science Digital Library

In this quick and simple activity about reflexes (third activity on the page), learners conduct a simple test to explore the knee jerk reflex, typically conducted at the doctor's office. In this version, learners work in pairs and use their hand to prompt the reflex (not a hammer!). This activity is one of several activities featured on this webpage related to human reflexes.

Chudler, Eric

2009-01-01

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

Caring Reflexivity  

ERIC Educational Resources Information Center

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

Rallis, Sharon F.; Rossman, Gretchen B.

2010-01-01

27

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

PubMed

The aim of the present work was to study the involvement of protein synthesis in the reconsolidation of memory at different periods of time after training. In mice trained in a conditioned reflex freezing model, memory was reactivated by a reminder combined with administration of the protein synthesis inhibitor cycloheximide. The results showed that suppression of protein synthesis on reactivation of memory 3, 6, and 24 h and 14 and 30 days after training impaired acquired conditioned reflex freezing. These data provide evidence that memories retrieved by a reminder require protein-dependent reorganization at both short (3-6 h) and long (14-30 days) periods after training. PMID:17457537

Murav'eva, E V; Anokhin, K V

2007-05-01

28

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

PubMed

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

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

2014-03-01

29

Primitive reflexes in Parkinson's disease.  

PubMed Central

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

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

1993-01-01

30

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

31

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

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

32

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

33

Modulation of Unconditioned Defensive Reflexes by a Putative Emotive Pavlovian Conditioned Stimulus  

Microsoft Academic Search

Four experiments showed differential modulation of defensive unconditioned responses (URs) in rabbits by contextual stimuli that Brandon and Wagner (1991) have shown similarly to modulate conditioned eyeblink responses. Two 30-s auditory cues, A and B, were differentially paired with shock. Tests were presentations of a response-eliciting probe stimulus within A, B, or a comparable blank interval. Experiments 1 and 2

Susan E. Brandon; Joan C. Bombace; William A. Falls; Allan R. Wagner

1991-01-01

34

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

Microsoft Academic Search

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

E. V. Murav’eva; K. V. Anokhin

2007-01-01

35

Teaching and learning critical accounting using media texts as reflexive devices: conditions for transformative action or reinforcing the status quo?  

Microsoft Academic Search

This paper considers the possibilities of accounting education being used in its transformative capacity. The use of “real world events” as presented by the media is used as an educational resource to bridge theory and practice. It is argued that the use of media texts as a practicum to enable praxis, must be reflexive. Whilst the opportunities for emancipation are

Mary A Kaidonis

2004-01-01

36

[Oculorespiratory reflex].  

PubMed

The lack of interest about oculorespiratory reflex (ORR) in surgery and experimental studies is obvious. However the authors insist on the importance of its clinical traduction. The purpose of this study is to determinate an experimental model with titration of stimulus (pressure or traction) and therapeutic test. Our first Results prove the clinic entity of O.R.R. In first conclusion, we can insist on the importance of ventilatory assistance during squint surgery and on the monitoring of PE CO2 and Sa O2. PMID:2225259

Thirion, B; Marchal, F; Pétry, L; George, J L; Crance, J P; Haberer, J P

1990-01-01

37

Wireless quantified reflex device  

NASA Astrophysics Data System (ADS)

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

Lemoyne, Robert Charles

38

The vestibulosympathetic reflex in humans: neural interactions between cardiovascular reflexes  

NASA Technical Reports Server (NTRS)

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

Ray, Chester A.; Monahan, Kevin D.

2002-01-01

39

Vestibular-Ocular Reflex  

NSDL National Science Digital Library

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

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

2013-01-30

40

The Reflexes of the Fundus Oculi  

PubMed Central

The fundus reflexes reveal, in a manner not yet completely understood, the texture and contour of the reflecting surfaces and the condition of the underlying tissues. In this way they may play an important part in the biomicroscopy of the eye. The physiological reflexes are seen at their best in the eyes of young subjects, in well-pigmented eyes, with undilated pupils and with emmetropic refraction. Their absence during the first two decades, or their presence after the forties, their occurrence in one eye only, their appearance, disappearance or change of character should suggest the possibility of some pathological state. The investigation and interpretation of the reflexes are notably assisted by comparing the appearances seen with long and short wave lights such as those of the sodium and mercury vapour lamps, in addition to the usual ophthalmoscopic lights. Most of the surface reflexes disappear in the light of the sodium lamp, sometimes revealing important changes in the deeper layers of the retina and choroid. The physiological reflexes, chiefly formed on the surface of the internal limiting membrane, take the forms of the familiar watered silk or patchy reflexes, the peri-macular halo, the fan reflex in the macular depression and the reflex from the foveal pit. The watered silk or patchy reflexes often show a delicate striation which follows the pattern of the nerve-fibre layer, or there may be a granular or criss-cross texture. Reflexes which entirely lack these indications of “texture” should be considered as possibly pathological. This applies to the “beaten metal” reflexes and to those formed on the so-called hyaloid membrane. The occurrence of physiological reflexes in linear form is doubtful, and the only admittedly physiological punctate reflexes are the so-called Gunn's dots. Surface reflexes which are broken up into small points or flakes are pathological, and are most frequently seen in the central area of the fundus in cases of pigmentary degeneration of the retina or after the subsidence of severe retinitis or retino-choroiditis. A mirror reflex from the layer of pigmented epithelium or from the external limiting membrane is sometimes recognizable in normal eyes, especially in the brunette fundus. In such, it forms the background to a striking picture of the fine circumfoveal vessels. Pathological reflexes from the level of the pigmented epithelium or of the external limiting membrane are also observed, and these often present a granular, frosted or crystalline appearance. They may indicate a senile change, or result from trauma or from retino-choroidal degeneraion. Somewhat similar reflexes may sometimes be present as small frosted patches anterior to the retinal vessels. Linear sinuous, whether appearing in annular form, as straight needles, as broader single sinuous lines, as the tapering, branched double reflexes of Vogt, or in association with traction or pressure folds, in the retina, are probably always pathological. By the use of selected light of long and short wave lengths, it can be shown that intraretinal or true retinal folds may exist with or without the surface reflexes which indicate a corresponding folding of the internal limiting membrane. On the other hand, superficial linear reflexes of various types may occur without evidence of retinal folding. Annular reflexes usually accompany a rounded elevation of the retina due to tumour, hæmorrhage or exudate, but may indicate the presence of rounded depressions; traction folds occur where there is choroido-retinal scarring, or in association with macular hole or cystic degeneraion at the macula; pressure folds in cases of orbital cyst, abscess or neoplasm; and the other linear reflexes in association with papillo-retinal œdema, for example, in retrobulbar neuritis, in hypertensive neuro-retinitis, in contusio bulbi and in anterior uveitis. Punctate reflexes, other than Gunn's dots, are also pathological. They may occur as one variety of “fragmented” surface reflexes, or as evidence of th

Ballantyne, A. J.

1940-01-01

41

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

ERIC Educational Resources Information Center

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

Pendery, Mary; Maltzman, Irving

1977-01-01

42

Sneeze reflex: facts and fiction.  

PubMed

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

Songu, Murat; Cingi, Cemal

2009-06-01

43

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

ERIC Educational Resources Information Center

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

Maltzman, Irving; And Others

1977-01-01

44

Assessment of Primitive Reflexes in High-risk Newborns  

PubMed Central

Background Assessment of primitive reflexes is one of the earliest, simplest, and most frequently used assessment tools among health care providers for newborns and young infants. However, very few data exist for high-risk infants in this topic. Among the various primitive reflexes, this study was undertaken particularly to describe the sucking, Babinski and Moro reflexes in high-risk newborns and to explore their relationships with clinical variables. Methods This study is a cross-sectional descriptive study. Sixty seven high-risk newborns including full-term infants required intensive care as well as premature infants were recruited in a neonatal intensive care unit using convenient sampling method. The sucking, Babinski and Moro reflexes were assessed and classified by normal, abnormal and absence. To explore their relationships with clinical variables, birth-related variables, brain sonogram results, and behavioral state (the Anderson Behavioral State Scale, ABSS) and mental status (the Infant Coma Scale, ICS) were assessed. Results The sucking reflex presented a normal response most frequently (63.5%), followed by Babinski reflex (58.7%) and Moro reflex (42.9%). Newborns who presented normal sucking and Babinski reflex responses were more likely to have older gestational age, heavier birth and current weight, higher Apgar scores, shorter length of hospitalization, better respiratory conditions, and better mental status assessed by ICS, but not with Moro reflex. Conclusions High risk newborns presented more frequent abnormal and absence responses of primitive reflex and the proportions of the responses varied by reflex. Further researches are necessary in exploring diverse aspects of primitive reflexes and revealing their clinical implication in the high-risk newborns that are unique and different to normal healthy newborns. Keywords Primitive reflex; High risk infants; Korean; Moro reflex; Sucking reflex; Babinski reflex; The Anderson Behavioral State Scale; Infant Coma Scale

Sohn, Min; Ahn, Youngmee; Lee, Sangmi

2011-01-01

45

Astronomical Data Reduction Workflows with Reflex  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

46

The spinal reflex cannot be perceptually separated from voluntary movements.  

PubMed

Both voluntary and involuntary movements activate sensors in the muscles, skin, tendon and joints. As limb movement can result from a mixture of spinal reflexes and voluntary motor commands, the cortical centres underlying conscious proprioception might either aggregate or separate the sensory inputs generated by voluntary movements from those generated by involuntary movements such as spinal reflexes. We addressed whether healthy volunteers could perceive the contribution of a spinal reflex during movements that combined both reflexive and voluntary contributions. Volunteers reported the reflexive contribution in leg movements that were partly driven by the knee-jerk reflex induced by a patellar tendon tap and partly by voluntary motor control. In one condition, participants were instructed to kick back in response to a tendon tap. The results were compared to reflexes in a resting baseline condition without voluntary movement. In a further condition, participants were instructed to kick forwards after a tap. Volunteers reported the perceived reflex contribution by repositioning the leg to the perceived maximum displacement to which the reflex moved the leg after each tendon tap. In the resting baseline condition, the reflex was accurately perceived. We found a near-unity slope of linear regressions of perceived on actual reflexive displacement. Both the slope value and the quality of regression fit in individual volunteers were significantly reduced when volunteers were instructed to generate voluntary backward kicks as soon as they detected the tap. In the kick forward condition, kinematic analysis showed continuity of reflex and voluntary movements, but the reflex contribution could be estimated from electromyography (EMG) recording on each trial. Again, participants' judgements of reflexes showed a poor relation to reflex EMG, in contrast to the baseline condition. In sum, we show that reflexes can be accurately perceived from afferent information. However, the presence of voluntary movement significantly impairs reflex perception. We suggest that perceptual separation between voluntary and reflex movement is poor at best. Our results imply that the brain has no clear marker for perceptually separating voluntary and involuntary movement. Attribution of body movement to voluntary or involuntary motor commands is surprisingly poor when both are present. PMID:24060990

Ghosh, Arko; Haggard, Patrick

2014-01-01

47

On Reflexive Data Models  

SciTech Connect

An information system is reflexive if it stores a description of its current structure in the body of stored information and is acting on the base of this information. A data model is reflexive, if its language is meta-closed and can be used to build such a system. The need for reflexive data models in new areas of information technology applications is argued. An attempt to express basic notions related to information systems is made in the case when the system supports and uses meta-closed representation of the data.

Petrov, S.

2000-08-20

48

The corneomandibular reflex1  

PubMed Central

Seven patients are presented in whom a prominent corneomandibular reflex was observed. These patients all had severe cerebral and/or brain-stem disease with altered states of consciousness. Two additional patients with less prominent and inconsistent corneomandibular reflexes were seen; one had bulbar amyotrophic lateral sclerosis and one had no evidence of brain disease. The corneomandibular reflex, when found to be prominent, reflects an exaggeration of the normal. Therefore one may consider the corneomandibular hyper-reflexia as possibly due to disease of the corticobulbar system. Images

Gordon, Robert M.; Bender, Morris B.

1971-01-01

49

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

PubMed

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

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

2012-06-01

50

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

Microsoft Academic Search

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

Pauline Maillou; Samuel W. Cadden; Frank Lobbezoo

2010-01-01

51

Dysautonomia, fibromyalgia and reflex dystrophy  

PubMed Central

Autonomic nervous system dysfunction observed in fibromyalgia, characterized without exception by a sympathetic hyperactivity and hyporeactivity, has been reported. However, several studies demonstrated reduced levels of norepinephrine and neuropeptide Y at rest and after tilt table in some patients, which was improved by beta-stimulating agents. These findings support heterogeneity in fibromyalgia-associated dysautonomia. Fibromyalgia could be a generalized sympathetic dystrophy since both conditions are activated by trauma and partly linked to sympathetic mechanisms. Yet they differ on several points: hormonal and neurochemical abnormalities are observed in fibromyalgia whereas activation by peripheral trauma and hyperosteolysis are observed in reflex sympathetic dystrophy.

Eisinger, Jean

2007-01-01

52

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

PubMed

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

Udalova, G P; Karas', A Ya

2006-11-01

53

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

54

Reflexivity and the Researcher: An Illumination  

ERIC Educational Resources Information Center

Is reflexivity the condition of taking account of the personality and presence of the researcher within the investigation? Some argue that it is and it is necessary because self-examination is commonplace in society today. Improving and building are common goals, and within education we are committed to questioning in order to examine, build, and…

Ryan, Thomas

2004-01-01

55

Monitoring of head injury by myotatic reflex evaluation  

PubMed Central

OBJECTIVES—(1) To establish the feasibility of myotatic reflex measurement in patients with head injury. (2) To test the hypothesis that cerebral dysfunction after head injury causes myotatic reflex abnormalities through disordered descending control. These objectives arise from a proposal to use reflex measurements in monitoring patients with head injury.?METHODS—The phasic stretch reflex of biceps brachii was elicited by a servo-positioned tendon hammer. Antagonist inhibition was evoked by vibration to the triceps. Using surface EMG, the amplitude of the unconditioned biceps reflex and percentage antagonist inhibition were measured. After standardisation in 16 normal adult subjects, the technique was applied to 36 patients with head injury across the range of severity. Objective (1) was addressed by attempting a measurement on each patient without therapeutic paralysis; three patients were also measured under partial paralysis. Objective (2) was addressed by preceding each of the 36 unparalysed measurements with an assessment of cerebral function using the Glasgow coma scale (GCS); rank correlation was employed to test a null hypothesis that GCS and reflex indices are unrelated.?RESULTS—In normal subjects, unconditioned reflex amplitude exhibited a positive skew requiring logarithmic transformation. Antagonist inhibition had a prolonged time course suggesting presynaptic mechanisms; subsequent measurements were standardised at 80 ms conditioning test interval (index termed "TI80").? Measurements were obtained on all patients, even under therapeutic paralysis (objective (1)). The unconditioned reflex was absent in most patients with GCS less than 5; otherwise it varied little across the patient group. TI80 fell progressively with lower GCS, although patients' individual GCS could not be inferred from single measurements. Both reflex indices correlated with GCS (p<0.01), thereby dismissing the null hypothesis (objective (2)).?CONCLUSION—Cerebral dysfunction in head injury is reflected in myotatic reflex abnormalities which can be measured at the bedside. With greater reproducibility, reflex measurements may assist monitoring of patients with head injury.??

Cozens, J; Miller, S.; Chambers, I.; Mendelow, A

2000-01-01

56

Reflexivity in derived categories  

Microsoft Academic Search

An adjoint pair of contravariant functors between abelian categories can be\\u000aextended to the adjoint pair of their derived functors in the associated\\u000aderived categories. We describe the reflexive complexes and interpret the\\u000aachieved results in terms of objects of the initial abelian categories. In\\u000aparticular we prove that, for functors of any finite cohomological dimension,\\u000athe objects of the

Francesca Mantese; Alberto Tonolo

2010-01-01

57

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

PubMed Central

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

Garrison, M. Kevin; Schmit, Brian D.

2014-01-01

58

Reflexive Accounts and Accounts of Reflexivity in Qualitative Data Analysis  

Microsoft Academic Search

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

Natasha S. Mauthner; Andrea Doucet

2003-01-01

59

Rhythmic arm cycling differentially modulates stretch and H-reflex amplitudes in soleus muscle.  

PubMed

During rhythmic arm cycling, soleus H-reflex amplitudes are reduced by modulation of group Ia presynaptic inhibition. This suppression of reflex amplitude is graded to the frequency of arm cycling with a threshold of 0.8 Hz. Despite the data on modulation of the soleus H-reflex amplitude induced by rhythmic arm cycling, comparatively little is known about the modulation of stretch reflexes due to remote limb movement. Therefore, the present study was intended to explore the effect of arm cycling on stretch and H-reflex amplitudes in the soleus muscle. In so doing, additional information on the mechanism of action during rhythmic arm cycling would be revealed. Although both reflexes share the same afferent pathway, we hypothesized that stretch reflex amplitudes would be less suppressed by arm cycling because they are less inhibited by presynaptic inhibition. Failure to reject this hypothesis would add additional strength to the argument that Ia presynaptic inhibition is the mechanism modulating soleus H-reflex amplitude during rhythmic arm cycling. Participants were seated in a customized chair with feet strapped to footplates. Three motor tasks were performed: static control trials and arm cycling at 1 and 2 Hz. Soleus H-reflexes were evoked using single 1 ms pulses of electrical stimulation delivered to the tibial nerve at the popliteal fossa. A constant M-wave and ~6% MVC activation of soleus were maintained across conditions. Stretch reflexes were evoked using a single sinusoidal pulse at 100 Hz given by a vibratory shaker placed over the triceps surae tendon and controlled by a custom-written LabView program. Results demonstrated that rhythmic arm cycling that was effective for conditioning soleus H-reflexes did not show a suppressive effect on the amplitude of the soleus stretch reflex. We suggest this indicates that stretch reflexes are less sensitive to conditioning by rhythmic arm movement, as compared to H-reflexes, due to the relative insensitivity to Ia presynaptic inhibition. PMID:21901451

Palomino, Andres F; Hundza, Sandra R; Zehr, E Paul

2011-10-01

60

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

61

Design of perturbation signals for the estimation of proprioceptive reflexes.  

PubMed

This study aimed to identify the functional contribution of reflexes to human motor control during posture maintenance. Continuous random force disturbances were applied at the hand while the subjects were instructed to minimize the deviation resulting from the force disturbances. The results were analyzed in the frequency domain with frequency response functions (FRFs). Two FRFs were evaluated: 1) the mechanical admittance and 2) the reflexive impedance, expressing the dynamic relation between position and muscle activation (assessed via electromyography, EMG). The reflexive impedance is a direct measure of the proprioceptive reflexes. To record all relevant dynamical characteristics of the arm, wide bandwidth signals were used as force disturbance. Distributing the power of the signal over fewer frequencies within the bandwidth improved the signal-to-noise-ratio SNR of the EMG recordings, facilitating reliable estimation of the reflexive impedance. The coherence indicated that the relation between force disturbance and EMG is linear under the given conditions and improved with the SNR. The method of designing disturbance signals and the estimation of the reflexive impedance are useful for studies aiming to quantify proprioceptive reflexes and to investigate its functionality. PMID:18440907

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

2008-05-01

62

Reflexive Planning for Later Life  

ERIC Educational Resources Information Center

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

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

2004-01-01

63

Gain control in reflex pathways  

Microsoft Academic Search

Summary form only given. A series of experiments was undertaken to determine the gain of the stretch reflex in decerebrate cats. Stretches are applied through a servo-controlled motor that receives length and velocity feedback which are adjusted so that it behaves like a spring of a particular stiffness. As the stiffness decreases the gain of the reflex increases until the

R. B. Stein; S. DeSerres; D. J. Bennett

1992-01-01

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

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

66

Reflex myoclonus in olivopontocerebellar atrophy.  

PubMed Central

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

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

1994-01-01

67

Calcitonin and reflex sympathetic dystrophy syndrome  

Microsoft Academic Search

Summary  \\u000aReflex sympathetic dystrophy syndrome is a difficult condition to treat. Many modalities have been proposed, all of them being clinically effective but whose efficacy is often difficult to assess, and has not been properly compared. A regimen of physical therapy (pressure therapy, antalgic electrotherapy and exercise therapy) with or without calcitonin was investigated in 24 patients randomly assigned to

C. Gobelet; J.-L. Meier; W. Schaffner; A. Bischof-Delaloye; J.-C. Gerster; P. Burckhardt

1986-01-01

68

Acoustic reflex measurement.  

PubMed

Middle ear muscle reflex (MEMR) measurements have been a part of the standard clinical immittance test battery for decades as a cross-check with the behavioral audiogram and as a way to separate cochlear from retrocochlear pathologies. MEMR responses are measured in the ear canal by using a probe stimulus (e.g., single frequency or broadband noise) to monitor admittance changes elicited by a reflex-activating stimulus. In the clinical MEMR procedures, one test yields changes in a single measurement (i.e., admittance) at a single pure tone (e.g., 226 or 1000 Hz). In contrast, for the wideband acoustic immittance (WAI) procedure,one test yields information about multiple measurements (e.g., admittance, power reflectance, absorbance) across a wide frequency range (e.g., 250 to 8000 Hz analysis bandwidth of the probe). One benefit of the WAI method is that the MEMR can be identified in a single test regardless of the frequency at which the maximum shift in the immittance measurement occurs; this is beneficial because maximal shifts in immittance vary as a function of age and other factors. Another benefit is that the wideband response analysis yields lower MEMR thresholds than with the clinical procedures. Lower MEMR thresholds would allow for MEMR decay tests in ears in which the activator levels could not be safely presented. Finally, the WAI procedures can be automated with objective identification of the MEMR, which would allow for use in newborn and other screening programs in which the tests are completed by nonaudiological personnel. PMID:23900179

Schairer, Kim S; Feeney, M Patrick; Sanford, Chris A

2013-07-01

69

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

70

Modification of cutaneous reflexes during visually guided walking.  

PubMed

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

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

2014-01-01

71

Effects of TMJ anesthesia and jaw gape on jaw-stretch reflexes in humans  

Microsoft Academic Search

Objective: To study the roles of afferent sensory inputs in the temporomandibular joint (TMJ) and of muscle length in the modulation of the jaw-stretch reflex in humans.Methods: Reflexes were evoked in both the masseter and temporalis muscles under standardized conditions in 11 young women. The study was performed in two sessions; experimental conditions were jaw gape and injection of local

F Lobbezoo; K Wang; I. H. A Aartman; P Svensson

2003-01-01

72

Vestibulo-spinal reflex mechanisms  

NASA Technical Reports Server (NTRS)

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

Reschke, M. F.

1981-01-01

73

Dysphoric milk ejection reflex: A case report  

PubMed Central

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

2011-01-01

74

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

75

Avian reflex and electroencephalogram responses in different states of consciousness.  

PubMed

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

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

2014-06-22

76

Introducing the reflex probability maps in the quantification of nociceptive withdrawal reflex receptive fields in humans  

Microsoft Academic Search

The aim of the present study was to improve the assessment of reflex receptive fields (RRF) in humans, using reflex sensitivity and reflex probability maps. Repeated electrical stimulation was applied to elicit the nociceptive withdrawal reflex (NWR) in fifteen healthy volunteers using two stimulation paradigms: fixed (FSI) and adjusted (ASI) stimulation intensities. Stimulation was applied on sixteen sites in the

José A. Biurrun Manresa; Michael B. Jensen; Ole K. Andersen

2011-01-01

77

Variable Patterned Pudendal Nerve Stimuli Improves Reflex Bladder Activation  

PubMed Central

We evaluated variable patterns of pudendal nerve (PN) stimuli for reflex bladder excitation. Reflex activation of the bladder has been demonstrated previously with 20–33 Hz continuous stimulation of PN afferents. Neuronal circuits accessed by afferent mediated pathways may respond better to physiological patterned stimuli than continuous stimulation. Unilateral PN nerve cuffs were placed in neurologically intact male cats. PN stimulation (0.5–100 Hz) was performed under isovolumetric conditions at bladder volumes up to the occurrence of distension evoked reflex contractions. Stimulus evoked reflex bladder contractions were elicited in eight cats. Across all experiments, bursting of 2–10 pulses at 100–200 Hz repeated at continuous stimulation frequencies evoked significantly larger bladder responses than continuous (single pulse) stimulation (52.0 ± 44.5%). Bladder excitation was also effective at 1 Hz continuous stimuli, which is lower than typically reported. Variable patterned pulse bursting resulted in greater evoked reflex bladder pressures and increased the potential stimulation parameter space for effective bladder excitation. Improved bladder excitation should increase the efficacy of neuroprostheses for bladder control.

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

2010-01-01

78

Intranasal Midazolam May Prevent Gagging Reflex: a Case Report  

PubMed Central

ABSTRACT Background Gagging can become a conditioned response that makes dental treatment difficult or impossible for both the individual and the dentist. The aim of this study is to report a 50 year old female and two children (15 and 11 years old) with exaggerated gag reflex referred to Faculty of Dentistry of Selçuk University. Methods During obtaining records, taking impression procedure was elicited the patients’ hypersensitive gagging reflex. Therefore, it was decided to administer intranasal midazolam to facilitate the taking of accurate dental impressions. After given verbal information about the procedure, 2.5 mg intranasal midazolam (Demizolam, Dem Medikal, Istanbul) were applied incrementally in both nostrils. Results Five minutes later; patients had no gagging reflex and allowed the clinician to take satisfying impressions. No serious adverse effects were observed and the patients remained cooperative during the entire procedure which was completed to the full satisfaction of all involved. The short absorption time and the fast relief process of anaesthetics transferred to the systemic circulatory system are important advantages of nasal application. Conclusions Intranasal midazolam may be very useful for the treatment of gag reflex probably effecting on the depression of upper airway reflex sensitivity.

Malkoc, Meral Arslan; Demir, Necla; Erdur, Aybuke; Apiliogullari, Seza

2013-01-01

79

Effect of cervicolabyrinthine impulsation on the spinal reflex apparatus  

NASA Technical Reports Server (NTRS)

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

Yarotskiy, A. I.

1980-01-01

80

The facial reflex of allergy.  

PubMed

The facial reflex, originally described by Franz Chvostek, is shown to be of value in allergy by assessing the relative irritability of muscle tissue (cardic, smooth, skeletal) and the effect of certain drugs frequently used by allergists upon them. PMID:222174

Breneman, J C

1979-06-01

81

Axillary Brachial Plexus Blockade for the Reflex Sympathetic Dystrophy Syndrome.  

ERIC Educational Resources Information Center

Reflex sympathetic dystrophy syndrome (RSD) is a neurogenic pain syndrome characterized by pain, vasomotor and dystrophic changes, and often motor impairments. This study evaluated the effectiveness of brachial plexus blockade with local anaesthetic drugs as a treatment for this condition. Three patients responded well; three did not. (DB)

Ribbers, G. M.; Geurts, A. C. H.; Rijken, R. A. J.; Kerkkamp, H. E. M.

1997-01-01

82

Quantifying the effects of voluntary contraction and inter-stimulus interval on the human soleus H-reflex.  

PubMed

The human soleus H-reflex is commonly tested as an indicator of the reflex excitability of the calf muscles with infrequent stimuli to a subject seated and at rest. However, the reflex varies widely with the level of voluntary contraction and with the time history of stimulation. We studied two aspects of this variation. Antagonist (tibialis anterior) activation decreases the response, while increasing agonist (soleus) activation increases the H-reflex to a peak after which it declines. In subjects with large H-reflexes at rest, the reflex peaked at low levels of contraction. In contrast, in subjects with small H-reflexes at rest, the reflex peaked at higher levels of contraction for reasons that were elucidated using a realistic computer model. A parabolic curve fitted the maximum amplitude of the H-reflex in the model and over the entire range of contractile levels studied. The second aspect studied was post-activation depression or homosynaptic depression (HD), which has been described previously as a reduction of a second H-reflex elicited shortly after an initial reflex. We confirmed the presence of HD in resting, seated subjects for intervals up to 4 s. However, by voluntarily activating the soleus muscle, HD was drastically reduced when seated and abolished when standing. This suggests that HD may be absent in normal, functional movements and perhaps in clinical conditions that alter H-reflexes. Meaningful, quantitative measurements of reflex excitability can only be made under voluntary activity that mimics the condition of interest. PMID:17562030

Stein, Richard B; Estabrooks, Kristen L; McGie, Steven; Roth, Michael J; Jones, Kelvin E

2007-09-01

83

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

84

Hypothesis: The nasal fatigue reflex  

Microsoft Academic Search

Natural selection results in adaptations. I suggest that unexplained fatigue may be an adaptive response to nasal impairment.\\u000a For macrosmatic animals, intact olfaction is necessary to detect predators. In such animals, any reflex (e.g., fatigue) triggered\\u000a by nasal dysfunction that limited exposure would offer great survival advantage. The “fatigued” animal would remain in its\\u000a protected environment, unexposed to hungry carnivores,

Alexander C. Chester

1993-01-01

85

[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

86

Sacral reflex latencies in tethered cord syndrome.  

PubMed

We performed electrophysiologic evaluation in three adult patients with diagnosis of tethered cord syndrome confirmed by magnetic resonance imaging. In addition to lower motor neuron lesion signs in the lumbar and sacral myomeres we noticed shortened latencies for the H and bulbocavernosus reflexes. H reflex latencies ranged from 23.3 to 26.0 ms; bulbocavernosus reflex latencies ranged from 18.2 to 20.2 ms. The low location of the conus medullaris accounts for the shortening of the monosynaptic H reflex and for a part of the shortening of the polysynaptic bulbocavernosus reflex, anoxia of the conus being probably another important factor. In the absence of previous description of alternative pathology accountable for such a shortening, our observations suggest that shortened sacral reflex latencies might be specific of the tethered cord syndrome. PMID:8431266

Hanson, P; Rigaux, P; Gilliard, C; Biset, E

1993-02-01

87

Excitability of the human trigeminal motoneuronal pool and interactions with other brainstem reflex pathways  

PubMed Central

We studied the properties of motoneurones and Ia-motoneuronal connections in the human trigeminal system, and their functional interactions with other brainstem reflex pathways mediated by non-muscular (A?) afferents. With surface EMG recordings we tested the recovery cycles of the heteronymous H-reflex in the temporalis muscle and the homonymous silent period in the masseter muscle both elicited by stimulation of the masseteric nerve at the infratemporal fossa in nine healthy subjects. In four subjects single motor-unit responses were recorded from the temporalis muscle. In six subjects we also tested the effect of the stimulus to the mental nerve on the temporalis H-reflex and, conversely, the effect of Ia input (stimulus to the masseteric nerve) on the R1 component of the blink reflex in the orbicularis oculi muscle. The recovery cycle of the H-reflex showed a suppression peaking at the 5-20 ms interval; conversely the time course of the masseteric silent period was facilitated at comparable intervals. The inhibition of the test H-reflex was inversely related to the level of background voluntary contraction. Single motor units were unable to fire consistently in response to the test stimulus at intervals shorter than 50 ms. Mental nerve stimulation strongly depressed the H-reflex. The time course of this inhibition coincided with the EMG inhibition elicited by mental nerve stimulation during voluntary contraction. The trigeminal Ia input facilitated the R1 component of the blink reflex when the supraorbital test stimulation preceded the masseteric conditioning stimulation by 2 ms. We conclude that the time course of the recovery cycle of the heteronymous H-reflex in the temporalis muscle reflects the after-hyperpolarization potential (AHP) of trigeminal motoneurones, and that the Ia trigeminal input is integrated with other brainstem reflexes.

Cruccu, G; Truini, A; Priori, A

2001-01-01

88

Soleus H-reflex graded depression by contralateral hip afferent feedback in humans.  

PubMed

The aim of this study was to establish the effects of contralateral hip oscillations on the ipsilateral soleus H-reflex. A servomotor system was utilized to impose bilateral hip oscillations at 0.5 Hz, while braces stabilized the joint position of both legs. The soleus H-reflex was evoked every 4 s during bilateral synchronous and asynchronous hip movements and during unilateral hip oscillations with the contralateral leg hyperextended or flexed. In all experimental conditions, a stimulus was delivered to the posterior tibial nerve while the ipsilateral leg was moving either into extension or flexion. Torques at the hip and ankle joints and activity from six muscles were recorded from both legs. The ipsilateral soleus H-reflex was profoundly depressed in all conditions. The reflex depression was less during asynchronous than synchronous hip oscillations. Further, the soleus H-reflex depression did not vary with the contralateral hip flexed or extended, but it was larger when the ipsilateral hip was moving in flexion. These findings demonstrate that sensory afferent feedback from the contralateral hip adjusts the amount of inhibition acting on the ipsilateral soleus H-reflex, supporting cross-leg reflex and heteronymous muscle afferents interactions in humans. PMID:19913521

Stanislaus, Vimal; Mummidisetty, Chaithanya K; Knikou, Maria

2010-01-15

89

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.

Szabadi, Elemer

2012-01-01

90

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

91

21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food...Diagnostic Devices § 890.1450 Powered reflex hammer. (a) Identification. A powered reflex hammer is a motorized device intended for...

2009-04-01

92

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

PubMed Central

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

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

2009-01-01

93

Diachronic Processes in the Evolution of Reflexives.  

ERIC Educational Resources Information Center

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

Kemmer, Suzanne

94

Roll tilt reflexes after vestibulospinal tract lesions  

Microsoft Academic Search

The effects of lesions of the vestibulospinal tracts on vestibular reflexes evoked by roll tilt in forelimb and neck extensors were examined in decerebrate cats. Sectioning the medial longitudinal fasciculus, which contains the medial vestibulospinal tract, had no major effect on the phase of the reflex, although some gain was usually lost at high stimulus frequencies. Spinal lesions at C2–C3,

A. D. Miller; P. S. Roossin; R. H. Schor

1982-01-01

95

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

PubMed Central

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

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

1995-01-01

96

Studies of the horizontal vestibulo-ocular reflex in spaceflight  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

97

Reflexivity: recursion and relationality in organizational research processes  

Microsoft Academic Search

Purpose – The paper seeks to support a better understanding of the types (or processes) of reflexivity which may be involved in the practice of organizational research, and the implications of reflexive practice for organizational researchers. Design\\/methodology\\/approach – A characterization of reflexivity as a process is developed from extant research, in four steps. First, the principal dimensions of reflexivity

Paul Hibbert; Christine Coupland; Robert MacIntosh

2010-01-01

98

Changes in the Achilles tendon reflexes following Skylab missions  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

99

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

ERIC Educational Resources Information Center

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

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

2004-01-01

100

The influence of an enkephalin derivative, DAGO, on the behavior and activity of neurons of the neocortex and hippocampus of rabbits during the development of defensive and inhibitory conditioned reflexes.  

PubMed

After the administration of a morphine-like opiate, DAGO (D), in a dose of 250 micrograms/kg, a decrease was observed in the probability of movements of a rabbit in response to light flashes, the signal for a defensive reflex. The level of the background impulse activity of the neurons gradually decreased in the sensorimotor cortex and in the hippocampus, and did not change in the visual cortex. The decrease and the recovery of the responses of the neurons to the reinforcing stimulus (electrodermal stimulation of the limb) proceeded unidirectionally in all of the areas of the cortex studied, while there were substantial differences in the relationship to the cortical area studied and to the biological significance of the stimulus in the dynamics of the responses to the inhibitory and reinforced light flashes. The identification of the features of the systemic organization of the neurons during training with change in the properties of the reinforcement under the influence of the preparation under study is discussed, as well as the similarity of some features in the mechanisms of the development of internal inhibition in the defensive situation and of the properties of positive reinforcement. PMID:2164170

Shul'gina, G I; Okhotnikov, N V; Ryzhov, S O; Cherdakova, M V

1990-01-01

101

Role of Optokinetic Stimulation in Vesibulospinal Reflexes.  

National Technical Information Service (NTIS)

Data are presented concerning the effect of optokinetic stimulation (OKS) on vestibulospinal reflexes and discusses mechanisms of interaction of the vestibular, optic, and proprioceptive sensors during their combined stimulation. The vestibulospinal refle...

Y. V. Krylov V. V. Ivanov A. A. Podshivalov V. V. Zaritskiy

1988-01-01

102

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

103

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

104

Orbicularis oculi reflex in brain death.  

PubMed Central

The early and late components of the orbicularis oculi reflex were absent bilaterally in three patients who fulfilled the clinical and electroencephalographic criteria of brain death. A response to peripheral facial nerve stimulation was obtained in all. These preliminary observations suggest that the study of the orbicularis oculi reflex is a simple, objective, bedside neurophysiological test of brain stem function, complementing the electroencephalogram in the diagnosis of brain death.

Mehta, A J; Seshia, S S

1976-01-01

105

Chronic cerebellar stimulation and developmental reflexes.  

PubMed

The changes in motor function in cerebral palsy patients produced by chronic anterior lobe cerebellar stimulation were documented with the Milani-Comparetti developmental scale, which allows comparison betweenfunctional gains and reflex patterns. Two patients with marked motor retardation and primitive reflexes were followed serially over several months of stimulation. Using these measures, the efficiency of chronic stimulation can be assessed, although many years will be needed to evaluate its role in treating motor disabilities. PMID:300429

Penn, R D; Etzel, M L

1977-04-01

106

Acute provoked reflex seizures induced by thinking.  

PubMed

Thinking epilepsy is a rare form of reflex epilepsy that can be induced by specific cognitive tasks, and occurs mainly in idiopathic generalized epilepsies. We report a case of complex partial seizures triggered by thinking in a young man with acute bacterial meningitis and a remote head injury. This case illustrates that thinking-induced reflex seizures can be partial and can be provoked by an acute brain insult. PMID:23114680

Nevler, Naomi; Gandelman-Marton, Revital

2012-11-01

107

A range of different stretch reflex responses in the human thumb.  

PubMed

1. Imposed sinusoids were used to assess the resistance to movement at the thumb interphalangeal joint.2. The resistance to high-frequency movements (> 12 Hz) increased when the subject exerted a large voluntary flexing force; this increase was attributable to a greater non-reflex resistance of the contracting flexor muscles. This resistance was essentially ;visco-elastic', and the force was phase-advanced on joint position. At moderately large forces (up to half maximal), however, the resistance changed with changing frequency, and over a range 4-12 Hz the vectors which represented joint stiffness described the wide path that is characteristic of an active stretch reflex (Brown, Rack & Ross, 1982a). At frequencies between about 4 and 6 Hz the force was sometimes phase-delayed on position, and the joint exhibited a negative viscous stiffness. When the voluntary flexing force was very large the reflex contributed less to the resisting force, which was then phase-advanced on position at all frequencies of movement.3. Large amplitude movements did not generate correspondingly large reflex responses; as the amplitude of movement was increased, the reflex component of the resisting force became relatively smaller and the total resisting force was then phase-advanced on joint position at all frequencies.4. The reflex component of the resisting force (as indicated by the excursion of the joint stiffness vectors) varied from subject to subject and from time to time; the reflex usually became more active late in an experiment when the subject had exerted flexing forces against the imposed movement for some minutes. Extreme fatigue, however, diminished the amount of reflex force.5. In some subjects the joint-stiffness records indicated a particularly vigorous reflex response at 8-11 Hz, in contrast to a rather feeble response at 6 or 7 Hz. It is suggested that the reflex pathways then had a relatively low impedance to afferent signals that were modulated at 8-11 Hz, related perhaps to the firing patterns of the most recently recruited motoneurones.6. Under the conditions of these experiments, it appears that the stretch reflex has too small a gain to function as a very effective error-controlled position servo-mechanism. PMID:7153922

Brown, T I; Rack, P M; Ross, H F

1982-11-01

108

Adductor T and H reflexes in humans.  

PubMed

In the belief that changes in the adductor reflex (AR) may be helpful in evaluating lumbar root and plexus lesions, expression of the AR was studied in 43 healthy human subjects. ARs elicited with an electronic reflex hammer were recorded from the inner side of the proximal thigh using needle and surface electrodes, and patellar reflexes (PRs) were recorded simultaneously. These reflexes were obtained by tapping the ipsilateral medial aspect of the knee, the contralateral patellar tendon, the ipsilateral and contralateral anterior superior iliac spines, and the Achilles tendon. The H reflex of the obturator nerve was also evaluated in 17 cases. ARs were evoked consistently by tapping the ipsilateral medial aspect of the knee and by contralateral patellar tap, and by tapping ipsilateral and contralateral anterior superior iliac spines when a needle recording electrode was used. Sometimes an Achilles tendon tap also elicited the AR ipsilaterally. By contrast, the PR could only be elicited by a tap to the ipsilateral patellar tendon. ARs have somewhat different features than other well-known tendon reflexes such as the PR and are recorded consistently when a needle electrode is used, being elicited from both distal and proximal areas of the legs by tapping the Achilles tendon or anterior superior iliac spines unilaterally or bilaterally. Their role in evaluating lumbar root disease and monitoring adductor spasticity merits investigation. PMID:16941659

Ertekin, Cumhur; Bademkiran, Fikret; Tataroglu, Cengiz; Aydogdu, Ibrahim; Karapinars, Nevin

2006-11-01

109

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.

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

2012-01-01

110

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.

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

2012-01-01

111

Reflex ring laser amplifier system  

DOEpatents

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

Summers, M.A.

1983-08-31

112

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

113

Management of reflex anoxic seizures in children.  

PubMed

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

Iyer, Anand; Appleton, Richard

2013-09-01

114

Influence of tonic neck reflexes on the upper limb stretch reflex in man  

Microsoft Academic Search

This study was designed to test the influence of tonic neck reflexes (TNR) on the elbow extensor muscles. Surface electromyography (EMG) of triceps brachii (TB), anconeus (ANC) and biceps brachii (BB) muscles were recorded simultaneously with elbow acceleration. Stretch reflex responses from the elbow extensors were analysed in seven healthy subjects for three head positions, two positions of the eyes

A. Le Pellec; B. Maton

1996-01-01

115

[Corneal reflex in normal and pathological subjects].  

PubMed

The orbicularis oculi response can be evoked both by mechanical stimulation of the cornea (corneal reflex) and by electrical stimulation of the skin overlying the supraorbital nerve (blink reflex). Mechanical stimuli to the cornea activate A delta and C free nerve endings of the corneal mucosa. Electrical stimuli to the supraorbital nerve activate A beta, A delta and C fibers of the nerve trunk. Both reflexes present a bilateral late response, but the blink reflex shows in addition an early ipsilateral component (R1), which has never been observed with the corneal stimulation in man. We have developed a simple technique of electrical stimulation of the cornea which provides stable responses and allows precise measurements of threshold and latency of the reflex. In normal subjects, the threshold ranged from 50 to 350 microA, and the maximal stimulus that the subject could bear (tolerance level) ranged from 1000 to 2500 microA. The minimal latency to tolerance level stimuli was 39 +/- 3 msec. The latency difference between the direct responses evoked from the two opposite corneas never exceeded 8 msec and the difference between the direct and consensual responses elicited from the same cornea never exceeded 5 msec. An early ipsilateral component similar to the R1 response of the blink reflex was not observed, even with supramaximal stimulation. The electrically evoked corneal reflex was normal in 10 cases of essential trigeminal neuralgia, while the responses showed significant abnormalities in 18 subjects submitted to thermocoagulation of the Gasserian ganglion as a treatment of neuralgic pain, as well as in 2 cases of symptomatic neuralgia.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:4001709

Manfredi, M; Berardelli, A; Cruccu, G; Fabiano, F

1985-01-01

116

The effects of asymmetric tonic neck reflex during reaching movement following stroke: Preliminary results  

Microsoft Academic Search

Previous studies and clinical observations reveal that stroke survivors show the resurgence of the asymmetric tonic neck reflex (ATNR) both in static and dynamic conditions during maximal efforts. This observation may imply more reliance on the brainstem pathways following stroke. However, the effect of ATNR during a dynamic condition that represents more natural movement, such as reaching, has not been

S. Lee; J. Yao; A. M. Acosta; J. P. A. Dewald

2009-01-01

117

Stretch reflex gain in cat triceps surae muscles with compliant loads  

PubMed Central

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

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

2002-01-01

118

Phase-dependent modulation of cutaneous reflexes in tibialis anterior muscle during passive stepping.  

PubMed

The purpose of this study was to determine whether the cutaneous reflex elicited in the tibialis anterior (TA) muscle would be modulated in a phase-dependent manner while human subjects were passively stepping on a treadmill (treadmill stepping) or in the air (air stepping). The passive stepping was produced by a robotic gait trainer, Lokomat. The cutaneous reflexes following electric stimulation to the distal tibial nerve were recorded at ten different phases of a step cycle under the condition of tonic dorsiflexion [10% of maximum electromyography activity (EMGmax)]. Cutaneous reflex EMG responses with peak latencies of 70-120 ms [middle latency responses (MLR)] were then analysed. The results showed that there were no visible differences in the background EMG activities at the ten phases or two passive stepping conditions. During treadmill stepping, however, the magnitude of the facilitatory reflex responses between the late stance and the early swing phase was strongly enhanced, whereas no clear modulation of the MLR during air stepping was observed. These results suggest that the load-related afferent information plays a key role in the modulation of the cutaneous reflex during human walking. PMID:18387261

Nakajima, Tsuyoshi; Kamibayashi, Kiyotaka; Takahashi, Makoto; Komiyama, Tomoyoshi; Nakazawa, Kimitaka

2008-02-01

119

Atypical Pupillary Light Reflex in Individuals with Autism.  

National Technical Information Service (NTIS)

Pupillary light reflex (PLR) refers to the involuntary response whereby the pupil size changes in response to a short flash light. In this project, we will evaluate the atypical dynamic pupillary light reflex (PLR) observed in children autism. In addition...

D. Q. Beversdorf G. Yao J. H. Miles S. E. Christ

2013-01-01

120

[Neuropathology of contralateral pain flexor reflexes].  

PubMed

Postmortem neuropathological and neuroanatomical--topographical examinations of brain section series of 10 patients with brain tumours of different histological type and localization with evidence of the Contralateral Pain Flexor Reflex (CPFR), described by Sayk (1982), were performed. In each case could be found an alteration or damage of functionally relevant structures of the ventrocaudal--lateral Thalamus, the intralaminar and intralaminar-reticular nuclei, of the Pulvinar thalami, the lemniscus medialis and the striopallidar nuclei formation by tumuorcellinfiltration and oedema. Possible ways of origin of the CPFR, pathophysiological possibilities and the prognostic relevance of this reflex are discussed. PMID:3312404

Schröter, P

1987-01-01

121

The Limits of Institutional Reflexivity in Bulgarian Universities  

ERIC Educational Resources Information Center

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

Slantcheva, Snejana

2004-01-01

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 seizures induced by micturition and defecation, successfully treated with clobazam and phenytoin.  

PubMed

We report a six-year-old girl with seizures induced by both micturition and defecation. Several days after unprovoked generalised tonic-clonic seizures, she developed reflex seizures characterised by the extension of both arms and rhythmic jerking of her upper body. No abnormal findings were noted on brain magnetic resonance imaging. Interictal electroencephalography (EEG) showed spike-and-wave activity on central electrode recording, and rhythmic fast activity was recorded by central electrodes during the ictal EEG upon micturition. The combination of clobazam and phenytoin was effective for both unprovoked and reflex seizures. Although some previous reports have described reflex seizures triggered by either micturition or defecation, this is the first case report of reflex seizures induced by both micturition and defecation in the same patient. Based on a comparison with previous cases of reflex seizures induced either by micturition or defecation, the neuronal pathway from the pelvic base musculature to the supplementary motor area may be responsible for the condition in our patient. PMID:21561835

Higuchi, Tsukasa; Fukuyama, Tetsuhiro; Misawa, Yuka; Inaba, Yuji; Ichikawa, Motoki; Koike, Kenichi

2011-06-01

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

Provoked and reflex seizures: surprising or common?  

PubMed

Most patients with epilepsy report that seizures are sometimes, or exclusively, provoked by general internal precipitants (such as stress, fatigue, fever, sleep, and menstrual cycle) and by external precipitants (such as excess alcohol, heat, bathing, eating, reading, and flashing lights). Some patients describe very exotic and precise triggers, like tooth brushing or listening to a particular melody. Nevertheless, the most commonly noticed seizure increasers by far are stress, lack of sleep, and fatigue. Recognized reflex seizure triggers are usually sensory and visual, such as television, discotheques, and video games. Visually evoked seizures comprise 5% of the total of 6% reflex seizures. The distinction between provocative and reflex factors and seizures seems artificial, and in many patients, maybe all, there is a combination of these. It seems plausible that all of the above-mentioned factors can misbalance the actual brain network; at times, accumulation of factors leads then to primary generalized, partial, or secondarily generalized seizures. If the provoking factors are too exotic, patients may be sent to the psychiatrist. Conversely, if the seizure-provoking fluctuating mechanisms include common habits and environmental factors, these may hardly be considered as provocative factors. Awareness of precipitating factors and its possible interactions might help us to unravel the pathophysiology of epilepsy and to change the notion that seizure occurrence is unpredictable. This article provides an overview of the epidemiology, classification, diagnosis, treatment, and especially similarities in the variety of provocative and reflex factors with resulting general hypotheses. PMID:22946728

Kasteleijn-Nolst Trenité, Dorothée G A

2012-09-01

127

Semantic Descriptors: The Case of Reflexive Verbs  

Microsoft Academic Search

This paper presents a semantic classification of reflexive verbs in Bulgarian, augmenting the morphosyntactic classes of verbs in the large Bulgarian Lexical Data Base - a language resource utilized in a number of Language Engineering (LE) applications. The semantic descriptors conform to the Unified Eventity Representation (UER), developed by Andrea Schalley. The UER is a graphical formalism, introducing the object-oriented

Milena Slavcheva

128

Reflex tetrode with unidirectional ion flow  

Microsoft Academic Search

Experimental results are reported which show that the backward-directed (and unusable) ion current in a reflex triode can be almost completely suppressed by adding a second anode, made of aluminized Mylar, 0.5 cm from the existing polyethylene anode. Proton-generation efficiencies in excess of 50% have been obtained.

J. A. Pasour; R. A. Mahaffey; J. Golden; C. A. Kapetasnakos

1978-01-01

129

Reflex Tetrode with Unidirectional Ion Flow  

Microsoft Academic Search

Experimental results are reported which show that the backward-directed (and unusable) ion current in a reflex triode can be almost completely suppressed by adding a second anode, made of aluminized Mylar, 0.5 cm from the existing polyethylene anode. Proton-generation efficiencies in excess of 50% have been obtained.

J. A. Pasour; R. A. Mahaffey; J. Golden; C. A. Kapetasnakos

1978-01-01

130

Yohimbine — facilitated acoustic startle reflex in humans  

Microsoft Academic Search

Preclinical studies have suggested the acoustic startle reflex (ASR) may be a useful animal model to investigate the neurochemical basis of anxiety and fear states. This work has revealed that the anxiogenic alpha-2 receptor antagonist, yohimbine, increases the amplitude of the ASR in laboratory animals. The present investigation evaluated the effects of yohimbine on the ASR in healthy subjects. Seven

C. A. Morgan; S. M. Southwick; C. Grillon; M. Davis; J. H. Krystal; D. S. Charney

1993-01-01

131

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

132

[Blockade of obturator reflex (author's transl)].  

PubMed

The obturator reflex is a frequent complication of the transurethral resection of bladder tumors, specially those localized at the side of bladder. The transurethral operation often must be interrupted, or changed into a transabdominal one, because of danger of bladder perforation or severe bleeding. In addition to spinal analgesia two techniques of obturator block are presented and their use is discussed. PMID:7446947

Hoffmann, P; Meyer, O

1980-10-01

133

Short reflex expirations (expiration reflexes) induced by mechanical stimulation of the trachea in anesthetized cats  

Microsoft Academic Search

Fifty spontaneously breathing pentobarbital-anesthetized cats were used to determine the incidence rate and parameters of short reflex expirations induced by mechanical stimulation of the tracheal mucosa (ERt). The mechanical stimuli evoked coughs; in addition, 67.6% of the stimulation trials began with ERt. The expiration reflex mechanically induced from the glottis (ERg) was also analyzed (99.5% incidence, p < 0.001 compared

Ivan Poliacek; Melanie J Rose; Lu Wen-Chi Corrie; Cheng Wang; Jan Jakus; Helena Barani; Albert Stransky; Hubert Polacek; Erika Halasova; Donald C Bolser

2008-01-01

134

[Variability of interspike intervals of human motor neurons during voluntary muscle contraction and tonic vibration reflex].  

PubMed

Firing of motor units of human soleus, triceps brachii and rectus femoris muscles was studied. Standard deviations of interspike intervals against mean intervals were plotted during voluntary muscle contraction and tonic vibration reflex. There was no significant difference between the results obtained under these conditions. PMID:1598125

Kozhina, G V; Person, R S

1992-01-01

135

Role of testosterone secretion and penile reflexes in sexual behavior and sperm competition in male rats: a theoretical contribution.  

PubMed

A number of experiments have documented that when male rats are exposed to female rats they undergo a marked increase in the secretion of luteinizing hormone and testosterone. This response can be conditioned to other, previously neutral, stimuli associated with mating. Recent work has highlighted the remarkable sensitivity of penile reflexes to fluctuations in blood concentration of testosterone. Other work has pointed to the function of penile reflexes in seminal plug removal and deposition. It is hypothesized that penile reflexes are potentiated by the increase in testosterone that occurs in response to sexually relevant cues and that the potentiated reflexes play a role in sperm competition during multi-male mating encounters. The sperm competition centers around a male rat's ability to dislodge seminal plugs left in the vagina by other males and to deposit his own plug as tightly as possible to resist dislodgement by another. PMID:6665072

Hart, B L

1983-12-01

136

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

PubMed Central

Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Methods Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Results Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects. Conclusion Post stroke, we found active posture tasking to be dominated by: 1) muscle weakness and 2) lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.

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

2009-01-01

137

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

138

Aging effects on posture-related modulation of stretch reflex excitability in the ankle muscles in humans.  

PubMed

The purpose of this study was to examine the effects of aging on posture-related changes of the stretch reflex excitability in the ankle extensor, soleus (SOL), and flexor, tibialis anterior (TA) muscles. Fourteen neurologically normal elderly (mean 68±6years) and 12 young (mean 27±3years) subjects participated. Under two postural conditions, upright standing (STD) and sitting (SIT), stretch reflex electromyographic (EMG) responses in the SOL/TA muscle were elicited by imposing rapid ankle dorsi-/plantar-flexion. Under the SIT condition, subjects were asked to keep the SOL background EMG level, which is identical to that under the STD condition. In the SOL muscle, both groups showed significant enhancement of the short-latency stretch reflex (SLR) response when the posture changed from SIT to STD. In the TA muscle, the young group showed significant enhancement of the middle- (MLR) and long-latency stretch reflex (LLR) when the posture changed from SIT to STD; no such modulation was observed in the elderly group. Since the TA stretch reflex responses under the STD condition were comparable in the young and elderly groups, the lack of posture-related modulation of the TA muscle in the elderly group might be explained by augmented stretch reflex excitability under the SIT condition. The present results suggest that the (1) SOL SLR responses are modulated both in the young and elderly subjects when the posture is changed from SIT to STD, (2) TA MLR and LLR responses are not modulated in the elderly subjects when the posture is changed from SIT to STD, while each response is same between the young and elderly in STD, and (3) the effect of aging on the posture-related stretch reflex differs in the SOL and TA muscles. PMID:22118785

Obata, Hiroki; Kawashima, Noritaka; Ohtsuki, Tatsuyuki; Nakazawa, Kimitaka

2012-02-01

139

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

PubMed

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

Lapole, Thomas; Pérot, Chantal

2012-02-01

140

Yaw sensory rearrangement alters pitch vestibulo-ocular reflex responses  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

141

Impact of aging on long-term ocular reflex adaptation.  

PubMed

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

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

2013-12-01

142

The muscle engram: the reflex that limits conventional occlusal treatment.  

PubMed

The engram (the masticatory "muscle memory") is shown to be a conditionable reflex whose muscle conditioning lasts less than two minutes, far shorter than previously thought. This reflex, reinforced and stored in the masticatory muscles at every swallow, adjusts masticatory muscle activity to guide the lower arch unerringly into its ICP. These muscle adjustments compensate for the continually changing intemal and external factors that affect the mandible's entry into the ICP. A simple quick experiment described in this article isolates the engram, enabling the reader to see its action clearly for the first time. It is urged that every reader perform this experiment. This experiment shows how the engram, by hiding the masticatory muscles' reaction (the hit-and-slide), limits the success of the therapist in achieving occlusion-muscle compatibility. This finding has major clinical implications. It means that, as regards the muscle aspect of treating occlusion, the dentist treating occlusion conventionally is working blind, a situation the neuromuscular school of occlusal thought seeks to correct. The controversy over occlusion continues. PMID:22128670

Lerman, Martin D

2011-10-01

143

Dependency of human neck reflex responses on the bandwidth of pseudorandom anterior-posterior torso perturbations.  

PubMed

The vestibulocollic (VCR) and cervicocollic (CCR) reflexes are essential to stabilize the head-neck system and to deal with unexpected disturbances. This study investigates how neck reflexes contribute to stabilization and modulate with perturbation properties. We hypothesized that VCR and CCR modulate with the bandwidth of the perturbation and that this modulation is maintained across amplitudes and influenced by the eyes being open or closed. Seated subjects were perturbed in an anterior-posterior direction. The perturbations varied in bandwidth from 0.3 Hz to a maximum of 1.2, 2.0, 4.0, and 8.0 Hz, at three amplitudes, and with eyes open and closed. Frequency response functions of head kinematics and neck muscle EMG demonstrated substantial changes with bandwidth and vision and minor changes with amplitude, which through closed-loop identification were attributed to neural (reflexive) modulation. Results suggest that both reflexes were attenuated when perturbations exceeded the system's natural frequency, thereby shifting from a head-in-space to a head-on-trunk stabilization tendency. Additionally, results indicate that reflexive and mechanical stiffness marginally exceed the negative stiffness due to gravity; a stabilization strategy which minimizes effort. With eyes closed, reflexes were attenuated further, presumably due to a reduced ability to discriminate self-motion, driving the system to a head-on-trunk stabilization strategy at the highest bandwidth. We conclude that VCR and CCR modulate with perturbation bandwidth and visual feedback conditions to maintain head-upright posture, but are invariant across amplitude changes. PMID:23329203

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

2013-04-01

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

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

146

Respiratory reflexes in the anesthetized miniature swine.  

PubMed

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

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

1987-12-01

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

The mammalian exercise pressor reflex in health and disease.  

PubMed

The exercise pressor reflex (a peripheral neural reflex originating in skeletal muscle) contributes significantly to the regulation of the cardiovascular system during exercise. Exercise-induced signals that comprise the afferent arm of the reflex are generated by activation of mechanically (muscle mechanoreflex) and chemically sensitive (muscle metaboreflex) skeletal muscle receptors. Activation of these receptors and their associated afferent fibres reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the cardiovascular response to exercise is augmented. Owing to the peripheral skeletal myopathy that develops in heart failure (e.g. muscle atrophy, decreased peripheral blood flow, fibre-type transformation and reduced oxidative capacity), the exercise pressor reflex has been implicated as a possible mechanism by which the cardiovascular response to physical activity is exaggerated in this disease. Accumulating evidence supports this conclusion. This review therefore focuses on the role of the exercise pressor reflex in regulating the cardiovascular system during exercise in both health and disease. Updates on our current understanding of the exercise pressor reflex neural pathway as well as experimental models used to study this reflex are presented. In addition, special emphasis is placed on the changes in exercise pressor reflex activity that develop in heart failure, including the contributions of the muscle mechanoreflex and metaboreflex to this pressor reflex dysfunction. PMID:16282366

Smith, Scott A; Mitchell, Jere H; Garry, Mary G

2006-01-01

149

An experimental model of oculorespiratory reflex.  

PubMed Central

An experimental study of the oculorespiratory reflex (ORR) was conducted on 20 albino rabbits using a square wave (SW) type of stimulus. The ORR could be elicited in 100% of animals. The medial rectus was observed to be most reflexogenic for ORR. The frequency and pattern of ORR was not affected by bilateral vagotomy, intravenous atropine or glycopyrrolate, but could be completely abolished by retrobular block. Images

Khurana, A K; Khurana, I; Yadav, R N; Singh, P I; Gombar, K K; Ahluwalia, B K

1992-01-01

150

Promoting Self-Reflexivity in Intercultural Education  

Microsoft Academic Search

Self-reflexivity—having an ongoing conversation with your whole self about what you are experiencing as you are experiencing it—is a crucial skill for interculturalists, and I have been seeking to promote it when teaching intercultural communication in English to stu- dents of varying nationalities. This article will review how I structured both a large, intro- ductory intercultural communication undergraduate course and

Adair Linn Nagata

2004-01-01

151

Analysis of muscle fiber conduction velocity enables reliable detection of surface EMG crosstalk during detection of nociceptive withdrawal reflexes  

PubMed Central

Background The nociceptive withdrawal reflex (NWR) is a polysynaptic spinal reflex that induces complex muscle synergies to withdraw a limb from a potential noxious stimulus. Several studies indicate that assessment of the NWR is a valuable objective tool in relation to investigation of various pain conditions. However, existing methodologies for NWR assessment evaluate standard surface electromyography (sEMG) measured over just one muscle and do not consider the possible interference of crosstalk originating from adjacent active muscles. The present study had two aims: firstly, to investigate to which extent the presence of crosstalk may affect NWR detection using a standardized scoring criterion (interval peak z-score) that has been validated without taking crosstalk into consideration. Secondly, to investigate whether estimation of muscle fiber conduction velocity can help identifying the propagating and non-propagating nature of genuine reflexes and crosstalk respectively, thus allowing a more valid assessment of the NWR. Results Evaluation of interval peak z-score did apparently allow reflex detection with high sensitivity and specificity (0.96), but only if the influence of crosstalk was ignored. Distinction between genuine reflexes and crosstalk revealed that evaluation of interval peak z-score incorporating a z-score threshold of 12 was associated with poor reflex detection specificity (0.26-0.62) due to the presence of crosstalk. Two different standardized methods for estimation of muscle fiber conduction velocity were employed to demonstrate that significantly different muscle fiber conduction velocities may be estimated during genuine reflexes and crosstalk, respectively. This discriminative feature was used to develop and evaluate a novel methodology for reflex detection from sEMG that is robust with respect to crosstalk. Application of this conduction velocity analysis (CVA) entailed reflex detection with excellent sensitivity (1.00 and 1.00) and specificity (1.00 and 0.96) for the tibialis anterior and soleus muscles. Conclusion This study investigated the negative effect of electrical crosstalk during reflex detection and revealed that the use of a previously validated scoring criterion may result in poor specificity due to crosstalk. The excellent performance of the developed methodology in the presence of crosstalk shows that assessment of muscle fiber conduction velocity allows reliable detection of EMG crosstalk during reflex detection.

2013-01-01

152

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

153

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

154

Social orienting: reflexive versus voluntary control  

PubMed Central

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

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

2010-01-01

155

The swallowing reflex and its significance as an airway defensive reflex  

PubMed Central

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

Nishino, Takashi

2013-01-01

156

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

157

Reflex Sympathetic Dystrophy: Recognition and Management for the Physician  

Microsoft Academic Search

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

Edward Carden

158

Changes in cough reflex sensitivity after cessation and resumption of cigarette smoking.  

PubMed

Previous studies have shown that healthy cigarette smokers have diminished cough reflex sensitivity compared to healthy nonsmokers. We have recently demonstrated that cough reflex sensitivity is enhanced soon after smoking cessation, suggesting that diminished cough sensitivity in smokers results from chronic cigarette smoke-induced desensitization of airway cough receptors. In this study, we evaluated cough reflex sensitivity to capsaicin (C(5)) in 11 chronic smokers who had discontinued smoking for at least 2 weeks, and then resumed smoking. Two weeks after smoking cessation there was a significant enhancement of cough reflex sensitivity; mean (+/-SEM) log C(5) decreased from 1.77+/-0.18 to 1.47+/-0.14 (p=0.01). All subjects resumed smoking after 2-12 weeks of abstinence. Repeat capsaicin cough challenge was performed 14-23 days after resumption of smoking. Mean log C(5) increased compared to the last value obtained during the smoking cessation period: 1.42+/-0.15 vs. 1.77+/-0.16 (p=0.0004). Mean log C(5) after resumption of smoking returned to almost exactly the baseline value. Our findings suggest that the sensitivity of airway cough receptors is a dynamic phenomenon, promptly affected and modulated by changes in environmental conditions, such as the presence or absence of cigarette smoke. PMID:17045500

Sitkauskiene, Brigita; Stravinskaite, Kristina; Sakalauskas, Raimundas; Dicpinigaitis, Peter V

2007-01-01

159

Reflex contractions of the ischiocavernosus muscles following electrical and pressure stimulations.  

PubMed

In a previous study, we have demonstrated that voluntary muscular contractions of the ischiocavernosus muscles (IC) correlate with changes in intracavernous pressure and, therefore, with penile rigidity. The purpose of our current research project was to verify whether reflex contractions of the IC muscles exist and under what conditions. Our results confirm that reflex contractions occur following electrical or pressure stimulations. Following electrical stimulation, the mean latency of the reflex contractions was 67.5 ms for the IC muscles and 34.9 ms for the bulbocavernosus muscles (BC). Following pressure stimulation, the pressure threshold necessary to elicit contractions of the IC muscles varied between 18.2 mm. Hg and 34.8 mm. Hg. We also observed that pressure variation (increase and decrease) rather than a relatively constant pressure is necessary to produce this reflex response. We interpret these results to suggest that pressure stimulations on the glans penis during coitus contribute to the erectile process and, specifically, to the increase in intracavernous pressure. These findings suggest the possibility of a physiotherapeutic management for patients with penile rigidity problems. PMID:3339760

Lavoisier, P; Proulx, J; Courtois, F

1988-02-01

160

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

161

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.

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

2012-01-01

162

Context-Specific Adaptation of Gravity-Dependent Vestibular Reflex Responses  

NASA Technical Reports Server (NTRS)

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

Shelhamer, Mark J.

1999-01-01

163

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

PubMed Central

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

Buzsaki, G

1982-01-01

164

A robot conditioned reflex system modeled after the cerebellum.  

NASA Technical Reports Server (NTRS)

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

Albus, J. S.

1972-01-01

165

Multi-MA reflex triode research.  

SciTech Connect

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

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

2010-08-01

166

Reflex peripheral vasoconstriction is diminished in older men.  

PubMed

The purpose of this study was to compare reflex control of limb blood flow in healthy young (Y; 26 +/- 2 yr) and older (O;61 +/- 2 yr) men during whole body cooling under resting conditions. To better isolate the effect of chronological age, the two age groups (n = 6 per group) were closely matched for maximal oxygen uptake, body surface area, skinfold thickness, and fat-free weight. Subjects sat in an environmentally controlled chamber clad in standardized (0.6-clo) light cotton clothing at a dry-bulb temperature (Tdb) of 28 degrees C. After 30 min, Tdb was decreased by 2 degrees C every 5 min until Tdb = 10 degrees C, where it was held constant for the remainder of the 120-min session. Esophageal and mean skin temperatures were monitored continuously. Forearm blood flow (FBF) was measured every 5 min by venous occlusion plethysmography by using a mercury-in-Silastic strain gauge while arm temperature between the wrist and elbow was clamped at 37.2 +/- 0.1 degrees C by localized warm air heating. In this way, limb vasoconstriction was driven solely by thermoregulatory reflexes and not by direct effects of localized cooling. Mean skin temperature decreased at a similar rate and to a similar extent (by approximately 6 degrees C over a 2-h period) in both age groups, whereas esophageal temperature was relatively unaffected. In response to the local heating, the Y group maintained a significantly higher FBF than did the O group during the initial 30 min but decreased FBF during the cooling phase at a greater rate and to a greater extent than did the O group, leading to a significantly lower FBF during the final 30 min (at Tdb = 10 degrees C). Because there was no age difference in the mean arterial pressure response, similar effects of age were seen on forearm vascular conductance (FBF/mean arterial pressure). It was concluded that older men have a diminished reflex limb vasoconstrictor response to skin cooling. Furthermore, this difference in control of peripheral blood flow appears to be related to age per se; i.e., it is not a reflection of age-related differences in maximal oxygen uptake or body composition. PMID:8929592

Kenney, W L; Armstrong, C G

1996-02-01

167

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.

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

2011-01-01

168

Emotion, Novelty, and the Startle Reflex: Habituation in Humans  

Microsoft Academic Search

Previous research with both animal and human subjects has shown that startle reflex magnitude is potentiated in an aversive stimulus context, relative to responses elicited in a neutral or appetitive context. In the present experiment, the same pleasant, unpleasant, and neutral picture stimuli were repeatedly presented to human subjects. Startle reflex habituation was assessed in each stimulus context and was

Margaret M. Bradley; Peter J. Lang; Bruce N. Cuthbert

1993-01-01

169

Vertical Location of the Corneal Light Reflex in Strabismus Photography  

Microsoft Academic Search

Objective: To improve the clinical documentation of strabismus by mathematically predicting and clinically verifying the location of a fixation target that produces a vertically centered corneal light reflex (first Purkinje im- age) in clinical photographs of the eye using a standard photographic flash unit. Materials and Methods: Mathematical modeling of the corneal light reflex during clinical photography was based on

David G. Hunter; David L. Guyton

1998-01-01

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

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

172

Approaches to Reflexivity: Navigating Educational and Career Pathways  

ERIC Educational Resources Information Center

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

Dyke, Martin; Johnston, Brenda; Fuller, Alison

2012-01-01

173

Bourdieu and Science Studies: Toward a Reflexive Sociology  

ERIC Educational Resources Information Center

Two of Bourdieu's fundamental contributions to science studies--the reflexive analysis of the social and human sciences and the concept of an intellectual field--are used to frame a reflexive study of the history and social studies of science and technology as an intellectual field in the United States. The universe of large, Ph.D.-granting…

Hess, David J.

2011-01-01

174

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

175

PROPRIOCEPTIVE REFLEXES IN THE LEGS OF CARCINUS MAENAS (L.)  

Microsoft Academic Search

The preceding paper dealt with the reflex responses to two tactile stimuli of the motor and inhibitor axons innervating the claw-opener muscle of the crab, Carcinus maenas (L.) (Bush, 1962). Peripheral inhibition, through the specific opener inhibitor, was shown to be primarily responsible for the observed reflex inhibition of claw opening. During these experiments it was noticed that if the

B. M. H. BUSH

176

The expiration reflex from the trachea and bronchi  

Microsoft Academic Search

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

M. Tatar; J. Hanacek; J. Widdicombe

2008-01-01

177

Stretch reflex contribution to soleus activation during spastic gait  

Microsoft Academic Search

The authors studied the ankle extensor stretch reflex contribution to locomotor EMG for spastic gait by relating ankle angular velocity and soleus electromyography (EMG). The perturbations induced by the load variation during free gait were sufficient to characterize the stretch reflex contribution to soleus EMG during the beginning of the stance phase. Dorsiflexion peaks in the averaged ankle angular velocity

Peter H. Veltink; M. Ladouceur; T. Sinkjaer

1998-01-01

178

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

179

Primitive Reflex Profile: Early Motor Diagnosis. Volumes I and II.  

National Technical Information Service (NTIS)

The Primitive Reflex Profile (PRP) is a quantitative examination technique used to evaluate nine primitive reflexes. The PRP was performed on a cohort of 448 infants examined serially at each well baby visit between birth and two years of age. Standardiza...

A. J. Capute P. J. Accardo F. B. Palmer R. C. Wachtel B. K. Shapiro

1981-01-01

180

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

181

Abnormalities of the blink reflex in Gilles de la Tourette syndrome  

Microsoft Academic Search

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

S J Smith; A J Lees

1989-01-01

182

Effects of remote noxious stimulation on exteroceptive reflexes in human jaw-closing muscles  

Microsoft Academic Search

Reflexes evoked by applying non-painful taps to an incisor tooth were recorded from the jaw closing masseter and temporal muscles of 21 human subjects. A series of inhibitory, excitatory, inhibitory and excitatory waves (the ‘Q, R, S and T’ waves of the post-stimulus electromyographic complex (PSEC)) occurred in full-wave rectified and averaged electromyograms. Conditioning by remote noxious stimulation (RNS; application

S. W. Cadden; H. W. van der Glas; F. Lobbezoo; A. van der Bilt

1996-01-01

183

Effect of afferent feedback and central motor commands on soleus H-reflex suppression during arm cycling.  

PubMed

Suppression of soleus H-reflex amplitude in stationary legs is seen during rhythmic arm cycling. We examined the influence of various arm-cycling parameters on this interlimb reflex modulation to determine the origin of the effect. We previously showed the suppression to be graded with the frequency of arm cycling but not largely influenced by changes in peripheral input associated with crank length. Here, we more explicitly explored the contribution of afferent feedback related to arm movement on the soleus H-reflex suppression. We explored the influence of load and rate of muscle stretch by manipulating crank-load and arm-muscle vibration during arm cycling. Furthermore, internally driven ("Active") and externally driven ("Passive") arm cycling was compared. Soleus H-reflexes were evoked with tibial nerve stimulation during stationary control and rhythmic arm-cycling conditions, including: 1) six different loads; 2) with and without vibration to arm muscles; and 3) Active and Passive conditions. No significant differences were seen in the level of suppression between the different crank loads or between conditions with and without arm-muscle vibration. Furthermore, in contrast to the clear effect seen during active cycling, passive arm cycling did not significantly suppress the soleus H-reflex amplitude. Current results, in conjunction with previous findings, suggest that the afferent feedback examined in these studies is not the primary source responsible for soleus H-reflex suppression. Instead, it appears that central motor commands (supraspinal or spinal in origin) associated with frequency of arm cycling are relatively more dominant sources. PMID:22956797

Hundza, S R; de Ruiter, Geoff C; Klimstra, M; Zehr, E Paul

2012-12-01

184

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

PubMed Central

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

2011-01-01

185

Reflex receptive fields are enlarged in patients with musculoskeletal low back and neck pain.  

PubMed

Pain hypersensitivity has been consistently detected in chronic pain conditions, but the underlying mechanisms are difficult to investigate in humans and thus poorly understood. Patients with endometriosis pain display enlarged reflex receptive fields (RRF), providing a new perspective in the identification of possible mechanisms behind hypersensitivity states in humans. The primary hypothesis of this study was that RRF are enlarged in patients with musculoskeletal pain. Secondary study end points were subjective pain thresholds and nociceptive withdrawal reflex (NWR) thresholds after single and repeated (temporal summation) electrical stimulation. Forty chronic neck pain patients, 40 chronic low back pain patients, and 24 acute low back pain patients were tested. Electrical stimuli were applied to 10 sites on the sole of the foot to quantify the RRF, defined as the area of the foot from where a reflex was evoked. For the secondary end points, electrical stimuli were applied to the cutaneous innervation area of the sural nerve. All patient groups presented enlarged RRF areas compared to pain-free volunteers (P<.001). Moreover, they also displayed lower NWR and pain thresholds to single and repeated electrical stimulation (P<.001). These results demonstrate that musculoskeletal pain conditions are characterized by enlarged RRF, lowered NWR and pain thresholds, and facilitated temporal summation, most likely caused by widespread spinal hyperexcitability. This study contributes to a better understanding of the mechanisms underlying these pain conditions, and it supports the use of the RRF and NWR as objective biomarkers for pain hypersensitivity in clinical and experimental pain research. PMID:23707309

Biurrun Manresa, José A; Neziri, Alban Y; Curatolo, Michele; Arendt-Nielsen, Lars; Andersen, Ole K

2013-08-01

186

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

National Technical Information Service (NTIS)

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 t...

R. J. Leigh T. Brandt

1992-01-01

187

Foot-sole reflex receptive fields for human withdrawal reflexes in symmetrical standing position  

Microsoft Academic Search

Human withdrawal-reflex receptive fields were assessed in 10 healthy subjects during standing with even support on both legs. Two electrical-stimulus intensities (1.2 and 2.2 times the pain threshold, PTh) were used. The painful stimuli were delivered in random order to 12 positions distributed over the foot sole. Tibialis anterior (TA), soleus (SO), vastus lateralis (VL), semitendinosus (ST), and iliopsoas (IL)

Ole K. Andersen; Finn Sonnenborg; Zlatko Matjacic; Lars Arendt-Nielsen

2003-01-01

188

Lower esophageal sphincter relaxation reflex kinetics: effects of peristaltic reflexes and maturation in human premature neonates.  

PubMed

We defined the sensory-motor characteristics of the lower esophageal sphincter relaxation (LESR) (stimulus threshold volume, response onset, and relaxation period, relaxation magnitude, nadir) during maturation in human neonates. We hypothesized that LESR kinetics differs during maturation and with peristaltic reflex type. Basal and adaptive esophageal motility testing was performed (N = 20 premature neonates) at 34.7 and 39.1 wk (time 1 and time 2). Effects of midesophageal provocation with graded stimuli (N = 1,267 stimuli, air and liquids) on LESR kinetics during esophagodeglutition response (EDR) and secondary peristalsis (SP) were analyzed by mixed models. Frequency of LESR with basal primary peristalsis were different during maturation (P = 0.03). During adaptive responses with maturation, 1) the frequencies of peristaltic reflexes and LESR were similar; 2) liquid stimuli resulted in a shorter LESR response latency and LESR nadir and greater LESR magnitude (all P < 0.05); 3) media differences were noted with LESR response latency (air vs. liquids, P < 0.02); and 4) infusion flow rate-LESR were different (P < 0.01 for air and liquids). Mechanistically, 1) frequency of LESR was greater during peristaltic reflexes at both times (vs. none, P < 0.0001); 2) LESR response latency, duration, and time to complete LESR were longer with EDR (all P < 0.05, vs. SP at time 2); and 3) graded stimulus volume LESR were different for air and liquids (P < 0.01). In conclusion, sensory-motor characteristics of LESR depend on the mechanosensitive properties of the stimulus (media, volume, flow), type of peristaltic reflex, and postnatal maturation. Maturation modulates an increased recruitment of inhibitory pathways that favor LESR. PMID:20864655

Pena, Eneysis M; Parks, Vanessa N; Peng, Juan; Fernandez, Soledad A; Di Lorenzo, Carlo; Shaker, Reza; Jadcherla, Sudarshan R

2010-12-01

189

Lower esophageal sphincter relaxation reflex kinetics: effects of peristaltic reflexes and maturation in human premature neonates  

PubMed Central

We defined the sensory-motor characteristics of the lower esophageal sphincter relaxation (LESR) (stimulus threshold volume, response onset, and relaxation period, relaxation magnitude, nadir) during maturation in human neonates. We hypothesized that LESR kinetics differs during maturation and with peristaltic reflex type. Basal and adaptive esophageal motility testing was performed (N = 20 premature neonates) at 34.7 and 39.1 wk (time 1 and time 2). Effects of midesophageal provocation with graded stimuli (N = 1,267 stimuli, air and liquids) on LESR kinetics during esophagodeglutition response (EDR) and secondary peristalsis (SP) were analyzed by mixed models. Frequency of LESR with basal primary peristalsis were different during maturation (P = 0.03). During adaptive responses with maturation, 1) the frequencies of peristaltic reflexes and LESR were similar; 2) liquid stimuli resulted in a shorter LESR response latency and LESR nadir and greater LESR magnitude (all P < 0.05); 3) media differences were noted with LESR response latency (air vs. liquids, P < 0.02); and 4) infusion flow rate-LESR were different (P < 0.01 for air and liquids). Mechanistically, 1) frequency of LESR was greater during peristaltic reflexes at both times (vs. none, P < 0.0001); 2) LESR response latency, duration, and time to complete LESR were longer with EDR (all P < 0.05, vs. SP at time 2); and 3) graded stimulus volume LESR were different for air and liquids (P < 0.01). In conclusion, sensory-motor characteristics of LESR depend on the mechanosensitive properties of the stimulus (media, volume, flow), type of peristaltic reflex, and postnatal maturation. Maturation modulates an increased recruitment of inhibitory pathways that favor LESR.

Pena, Eneysis M.; Parks, Vanessa N.; Peng, Juan; Fernandez, Soledad A.; Di Lorenzo, Carlo; Shaker, Reza

2010-01-01

190

The milk ejection reflex in the pig  

PubMed Central

1. The milk ejection reflex in response to suckling was studied in conscious sows by continuous recording of intramammary pressure, radioimmunoassay of plasma concentrations of neurohypophysial hormones, and observation of the behaviour of the sows and piglets. 2. A regular pattern of nursing, suckling and milk ejection was observed. The mean duration of the suckling period was 6·3 min. Over 144 suckling periods, 113 milk ejections were recorded. Each milk ejection was characterized by a sudden rise in intramammary pressure reaching 20-49 mmHg, and lasting 8-41 sec. Milk ejections occurred only once per suckling period, at a mean interval of 44·3 min. 3. Each milk ejection occurred with a mean latency of 2·4 min from the onset of a period of initial massage of the udders by the piglets, and was coincident with a period of quiet suckling when the piglets were consuming milk. The onset of nursing was signalled by the sows grunting in a rhythmic manner. In most cases, the frequency of grunts, at first low, increased suddenly 23 sec before milk ejection. 4. During eighteen suckling periods leading to milk ejection, neurohypophysial hormone assays performed on serial blood samples showed an increase in plasma concentration of oxytocin up to 30 sec before milk ejection. The concentration of lysine—vasopressin did not rise above basal levels. 5. In 21·4% of the suckling periods, no rise in intramammary pressure was observed. In these `incomplete sucklings', the sow usually failed to grunt rapidly, and the piglets obtained no milk. For three of these periods, hormone assay showed no increase in oxytocin or vasopressin concentrations in blood. 6. Oxytocin given intravenously produced variations in intramammary pressure which depended on the dose and the rate of injection. Rapid injections of 25-50 m-u. oxytocin, caused milk ejections similar to those induced by suckling. When oxytocin was administered at different rates, the faster the injection, the shorter the latency and the higher the amplitude of the response. Plasma concentrations of oxytocin after injection of 25 m-u. were similar to those observed during reflex milk ejection. 7. Trains of electrical pulses were applied to the posterior pituitary of four anaesthetized sows. At frequencies of stimulation above 10 Hz, a rise in intramammary pressure and an increase in plasma oxytocin and vasopressin concentrations were observed. At frequencies of stimulation of 30-50 Hz, the response of the mammary gland and the time course of the variations in oxytocin plasma concentrations were similar to those observed during natural reflex milk ejection. 8. It is concluded that reflex milk ejections during suckling in the pig are caused by the intermittent and spurt-like release of about 25 m-u. oxytocin, without concomitant vasopressin release. It is postulated that the release of oxytocin is probably precipitated by a brief and massive activation of oxytocin-secreting neurones in the hypothalamus. Central mechanisms controlling the intermittent release of oxytocin are discussed.

Ellendorff, F.; Forsling, M. L.; Poulain, D. A.

1982-01-01

191

Vestibulospinal reflexes as a function of microgravity  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

192

Aerial righting reflexes in flightless animals.  

PubMed

Animals that fall upside down typically engage in an aerial righting response so as to reorient dorsoventrally. This behavior can be preparatory to gliding or other controlled aerial behaviors and is ultimately necessary for a successful landing. Aerial righting reflexes have been described historically in various mammals such as cats, guinea pigs, rabbits, rats, and primates. The mechanisms whereby such righting can be accomplished depend on the size of the animal and on anatomical features associated with motion of the limbs and body. Here we apply a comparative approach to the study of aerial righting to explore the diverse strategies used for reorientation in midair. We discuss data for two species of lizards, the gecko Hemidactylus platyurus and the anole Anolis carolinensis, as well as for the first instar of the stick insect Extatosoma tiaratum, to illustrate size-dependence of this phenomenon and its relevance to subsequent aerial performance in parachuting and gliding animals. Geckos can use rotation of their large tails to reorient their bodies via conservation of angular momentum. Lizards with tails well exceeding snout-vent length, and correspondingly large tail inertia to body inertia ratios, are more effective at creating midair reorientation maneuvers. Moreover, experiments with stick insects, weighing an order of magnitude less than the lizards, suggest that aerodynamic torques acting on the limbs and body may play a dominant role in the righting process for small invertebrates. Both inertial and aerodynamic effects, therefore, can play a role in the control of aerial righting. We propose that aerial righting reflexes are widespread among arboreal vertebrates and arthropods and that they represent an important initial adaptation in the evolution of controlled aerial behavior. PMID:21930662

Jusufi, Ardian; Zeng, Yu; Full, Robert J; Dudley, Robert

2011-12-01

193

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

194

Reflexes from the lungs and airways: historical perspective.  

PubMed

Historical aspects of respiratory reflexes from the lungs and airways are reviewed, up until about 10 yr ago. For most of the 19th century, the possible reflex inputs into the "respiratory center," the position of which had been identified, were very speculative. There was little concept of reflex control of the pattern of breathing. Then, in 1868, Breuer published his paper on "The self-steering of respiration via the Nervus Vagus." For the first time this established the role of vagal inflation and deflation reflexes in determining the pattern of breathing. Head later extended Breuer's work, and Kratschmer laid a similar basis for reflexes from the nose and larynx. Then, 50-60 yr later, the development of the thermionic valve and the oscilloscope allowed recording action potentials from single nerve fibers in the vagus. In 1933, Adrian showed that slowly adapting pulmonary stretch receptors were responsible for the inflation reflex. Later, Knowlton and Larrabee described rapidly adapting receptors and showed that they mediated deep augmented breaths and the deflation reflex. Still later, it was established that rapidly adapting receptors were, at least in part, responsible for cough. In 1954, Paintal began his study of C-fiber receptors (J receptors), work greatly extended by the Coleridges. Since approximately 10 yr ago, when the field of this review stops, there has been an explosion of research on lung and airway receptors, many aspects of which are dealt with in other papers in this series. PMID:16601307

Widdicombe, John

2006-08-01

195

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

SciTech Connect

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

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

1995-07-01

196

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

SciTech Connect

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

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

1995-08-01

197

Presynaptic inhibition of monosynaptic reflexes in the lower limbs of subjects with upper motoneuron disease.  

PubMed Central

Presynaptic inhibition of muscle spindle Ia afferents by group I afferents from the same and other muscles has been studied in the lower limbs of subjects with upper motoneuron lesions. The experiments utilised conditioning of soleus test monosynaptic reflexes during controlled voluntary contraction. The protocol was designed to isolate presynaptic inhibition from postsynaptic components. The relation between estimate of inhibition and test reflex amplitude was examined. The subjects showed less inhibition than controls at all levels of voluntary torque investigated (less than or equal 15 Nm). Two thirds had weak inhibition which did not show the decrease during muscle contraction characteristic of controls. The degree of difference from the normal situation correlated with severity of the clinical sign (weakness of voluntary ankle flexion).

Iles, J F; Roberts, R C

1986-01-01

198

Reversible abnormalities of the Hering Breuer reflex in acrylamide neuropathy.  

PubMed Central

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

Satchell, P

1985-01-01

199

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

ERIC Educational Resources Information Center

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

Taylor, Myra; Houghton, Stephen; Chapman, Elaine

2004-01-01

200

Inhibition of monosynaptic reflexes in the human lower limb.  

PubMed Central

1. Presynaptic inhibition of muscle spindle Ia afferents by afferents from the same and other muscles has been studied in the human lower limb. The experiments have utilized conditioning of test monosynaptic reflexes by vibration of both the test and other muscles. 2. The pattern of inhibition invariably includes autogenetic actions. 3. There are powerful effects from flexor to extensor Ia afferents. Actions from flexor to flexor, and from extensor to extensor, are weaker. Actions from extensors to flexors are very weak. 4. The strength of presynaptic inhibition from one muscle type to another weakens as the muscles considered become more anatomically distant. 5. The inhibition studied both by vibration and by electrical conditioning stimulation of nerves becomes weaker during voluntary isometric contraction of the test muscle. It is strongest at rest and during antagonist contraction. 6. Evidence is provided suggesting that descending control is the primary cause of this modulation of inhibition during contraction. 7. Stimulation of afferents in cutaneous nerves reduces group I presynaptic inhibition of Ia afferents.

Iles, J F; Roberts, R C

1987-01-01

201

Analysis of the Vestibulo-Ocular Counterroll Reflex in Primates.  

National Technical Information Service (NTIS)

The vestibulo-ocular reflex manifest by counterroll was used to determine the response dynamics of the vestibular system and alterations in these dynamics subsequent to +Gx exposure. Sic rhesus monkeys were tested before and after acceleration exposure to...

A. M. Junker C. R. Replogle K. A. Smiles R. Wheeler R. D. Brown

1971-01-01

202

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.

Panikkar, Bindu; Smith, Natasha; Brown, Phil

2013-01-01

203

REFLEX MODIFICATION AND THE ASSESSMENT OF SENSORY DYSFUNCTION  

EPA Science Inventory

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

204

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

PubMed

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

Baraniuk, James N; Merck, Samantha J

2008-04-01

205

Neuroanatomical basis of Sandifer's syndrome: a new vagal reflex?  

PubMed

Sandifer's syndrome is a gastrointestinal disorder with neurological features. It is characterized by reflex torticollis following deglutition in patients with gastroesophageal reflux and/or hiatal hernia. The authors believe that neurological manifestations of the syndrome are the consequence of vagal reflex with the reflex center in nucleus tractus solitarii (NTS). Three models for the neuroanatomical basis of the hypothetic reflex arc are presented. In the first one the hypothetic reflex arc is based on the classic hypothesis of two components nervus accessorius (n.XI) - radix cranialis (RC) and radix spinalis (RS) The nervous impulses are transmitted by nervus vagus (n.X) general visceral afferent (GVA) fibers to NTS situated in medulla oblongata, then by interneuronal connections on nucleus ambiguus (NA) and nucleus dorsalis nervi vagi (NDX). Special visceral efferent fibers (SVE) impulses from NA are in part transferred to n.XI ramus externus (RE) (carrying the majority of general somatic efferent (GSE) fibers) via hypothetic anastomoses in the region of foramen jugulare. This leads to contraction of trapezius and sternocleidomastoideus muscles, and the occurrence of intermittent torticollis. In the second suggested neuroanatomical model the hypothetic reflex arc is organized in the absence of n.XI RC, the efferent part of the reflex arc continues as NA, which is motor nucleus of nervus glossopharyngeus (n.IX) and n.X in this case while distal roots of n.XI that appear at the level of the olivary nucleus lower edge represent n.X roots. In the third presented model the hypothetic reflex arc includes no jugular transfer and could be realized via interneuronal connections directly from NTS to the spinal motoneurons within nucleus radicis spinalis nervi accessorii (NRS n.XI) or from NA to NRS n.XI. The afferent segment of the postulated reflex arc in all three models is mediated via n.X. We conclude that Sandifer's syndrome is a clinical manifestation of another vagal reflex that could be termed a "vagocervical" or "esophagocervical" reflex, based on the neuroanatomical hypotheses elaborated in this paper. PMID:18031943

Cerimagic, Denis; Ivkic, Goran; Bilic, Ervina

2008-01-01

206

Emetic stimulation inhibits the swallowing reflex in decerebrate rats  

Microsoft Academic Search

The effects of emetic stimulation on the swallowing reflex were investigated in decerebrated rats. Hypoxia, gastric distension and LiCl administration were used as emetic stimulations. The swallowing reflex was elicited by electrical stimulation of the superior laryngeal nerve (SLN, 20 Hz, 3–5 V, 0.3 ms duration) for 20 s. To examine the effect of hypoxia, nitrogen gas was inhaled under artificial ventilation. There were

Chiharu Kurozumi; Ryuzo Yamagata; Naoyuki Himi; Tomoshige Koga

2008-01-01

207

Reflex antennal movements in the spiny lobster, Palinurus elephas  

Microsoft Academic Search

1.Reflex antennal movements in the frontal plane, brought about by movement at the J1 joint, occur in the spiny lobster,Palinurus elephas, in response to tilting movements of a platform held under the animal's legs. Imposed movements of the J1 joint give rise to resistance reflexes. Experiments in which the two stimuli are delivered with different timing relations demonstrate that the

D. M. Neil; W. J. P. Barnes; M. D. Burns

1982-01-01

208

Mechanical Characteristics of Reflex Durign Upright Posture in Paralyzed Subjects  

NASA Astrophysics Data System (ADS)

The characteristics of flexor reflexes have been investigated in the previous studies with human subjects who were seated or supine position. However, researchers did not describe how the spinal circuits are used in different hip angles for paralyzed subjects, such as the standing position with walker or cane. In upright posture the compatibility between a flexor reflex of leg and body balance is a special problem for lower limb injured subjects. Therefore, the purpose of this study was to investigate the effects of hip angle change on the flexor reflex evoked in standing paralyzed subjects supported by walker. In this study, six spinal cord injured and four stroke subjects were recruited through the inpatient physical therapy clinics of Korea national rehabilitation hospital. A single axis electronic goniometer was mounted on the lateral side of the hip joint of the impaired limb to record movements in the sagittal plane at this joint. The electronic goniometer was connected to a data acquisition system, through amplifiers to a computer. Since subject' posture influenced characteristics of the flexion reflex response, the subjects were supported in an upright posture by the help of parallelogram walder. Two series of tests were performed on each leg. The first series of the tests investigated the influence of hip angle during stationary standing posture on flexion reflex response. The hip angle was adjusted by the foot plate. The second examined the effect of the voluntary action of subject on swing motion during the gait. The electrically induced flexion reflex simultaneously produced the flexion of the hip, knee and dorsiflexion of the ankle enabling the swing phase of walking. Form the experimental results we observed that the reflex response of hip joint was largerwith the hip in the extended position than in the flexed position during standing posture. Under voluntary movement on flexion reflex during gaint, the peak hip angle induced by stimulation was increased in spinal cord injury and stroke patients by subject' voluntary movement.

Kim, Yongchul; Youm, Youngil; Lee, Bumsuk; Kim, Youngho; Choi, Hyeonki

209

Attentional control and reflexive orienting to gaze and arrow cues  

Microsoft Academic Search

A wealth of data indicate that central spatially nonpredictive eyes and arrows trigger very similar reflexive spatial orienting,\\u000a although the effects of eyes may be more strongly reflexive (e.g., Friesen, Ristic, & Kingstone, 2004). Pratt and Hommel (2003)\\u000a recently reported that the orienting effect for arrows is sensitive to arbitrary cue-target color contingencies; for example,\\u000a an attentional orienting effect for

Jelena Ristic; Alissa Wright; Alan Kingstone

2007-01-01

210

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.

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

2013-01-01

211

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

212

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

PubMed

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

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

2006-05-01

213

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

214

Auditory Brainstem Circuits That Mediate the Middle Ear Muscle Reflex  

PubMed Central

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

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

2013-01-01

215

Noncommutative control in the rotational vestibuloocular reflex.  

PubMed

To investigate the role of noncommutative computations in the oculomotor system, three-dimensional (3D) eye movements were measured in seven healthy subjects using a memory-contingent vestibulooculomotor paradigm. Subjects had to fixate a luminous point target that appeared briefly at an eccentricity of 20 degrees in one of four diagonal directions in otherwise complete darkness. After a fixation period of approximately 1 s, the subject was moved through a sequence of two rotations about mutually orthogonal axes in one of two orders (30 degrees yaw followed by 30 degrees pitch and vice versa in upright and 30 degrees yaw followed by 20 degrees roll and vice versa in both upright and supine orientations). We found that the change in ocular torsion induced by consecutive rotations about the yaw and the pitch axis depended on the order of rotations as predicted by 3D rotation kinematics. Similarly, after rotations about the yaw and roll axis, torsion depended on the order of rotations but now due to the change in final head orientation relative to gravity. Quantitative analyses of these ocular responses revealed that the rotational vestibuloocular reflexes (VORs) in far vision closely matched the predictions of 3D rotation kinematics. We conclude that the brain uses an optimal VOR strategy with the restriction of a reduced torsional position gain. This restriction implies a limited oculomotor range in torsion and systematic tilts of the angular eye velocity as a function of gaze direction. PMID:17989243

Tchelidze, Tamara; Hess, Bernhard J M

2008-01-01

216

Compensatory adrenal growth - A neurally mediated reflex  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

217

Artificial balancer - supporting device for postural reflex.  

PubMed

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

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

2012-02-01

218

Reflex receptive fields for human withdrawal reflexes elicited by non-painful and painful electrical stimulation of the foot sole  

Microsoft Academic Search

Objectives: Human withdrawal reflex receptive fields (RRFs) were assessed for 4 different electrical stimulus intensities, ranging from below the pain threshold (PTh) to up to two times the PTh intensity (0.8×, 1.2×, 1.6×, and 2.0×PTh).Methods: Thirteen subjects participated, and the reflexes were recorded in a sitting position. The stimuli were delivered in random order to 12 positions distributed over the

Ole K Andersen; Finn A Sonnenborg; Lars Arendt-Nielsen

2001-01-01

219

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.

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

220

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

PubMed

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

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

2009-04-01

221

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

222

A method of reflexive balancing in a pragmatic, interdisciplinary and reflexive bioethics.  

PubMed

In recent years there has been a wealth of literature arguing the need for empirical and interdisciplinary approaches to bioethics, based on the premise that an empirically informed ethical analysis is more grounded, contextually sensitive and therefore more relevant to clinical practice than an 'abstract' philosophical analysis. Bioethics has (arguably) always been an interdisciplinary field, and the rise of 'empirical' (bio)ethics need not be seen as an attempt to give a new name to the longstanding practice of interdisciplinary collaboration, but can perhaps best be understood as a substantive attempt to engage with the nature of that interdisciplinarity and to articulate the relationship between the many different disciplines (some of them empirical) that contribute to the field. It can also be described as an endeavour to explain how different disciplinary approaches can be integrated to effectively answer normative questions in bioethics, and fundamental to that endeavour is the need to think about how a robust methodology can be articulated that successfully marries apparently divergent epistemological and metaethical perspectives with method. This paper proposes 'Reflexive Bioethics' (RB) as a methodology for interdisciplinary and empirical bioethics, which utilizes a method of 'Reflexive Balancing' (RBL). RBL has been developed in response to criticisms of various forms of reflective equilibrium, and is built upon a pragmatic characterization of Bioethics and a 'quasi-moral foundationalism', which allows RBL to avoid some of the difficulties associated with RE and yet retain the flexible egalitarianism that makes it intuitively appealing to many. PMID:23444909

Ives, Jonathan

2014-07-01

223

Maternal Separation Uncouples Reflex From Spontaneous Voiding in Rat Pups  

PubMed Central

Purpose Rat pups only void when the perigenital-bladder reflex is activated by the mother rat licking the perineum. Maternal separation causes bladder distention as well as stress responses and anxiety behaviors in adult rats. We determined if MS would change voiding reflex maturation in neonatal rats. Materials and Methods A total of 14 Sprague-Dawley rat pups were subjected to 6 hours of daily MS and 17 were subjected to 6 hours of MS with bladder emptying by perigenital stimulation at 3 hours on postnatal days 2 to 14. Age matched controls for the 2 groups remained with the mother. Spontaneous voiding in awake pups from 1 to 3 weeks was monitored in a metabolic cage and perigenital-bladder reflex latency was determined from 1 to 7 weeks. Cystometry was performed at 9 weeks with the rats under urethane anesthesia. Results Spontaneous voiding began at 3 weeks in all animals. The latency of the perigenital-bladder reflex at 3 weeks was shorter than the latency at 2 days in MS animals (3.3 vs 6.4 seconds, p < 0.01) but not in control or MSPG animals. MS animals maintained the perigenital-bladder reflex 2 weeks longer than control animals. The spontaneous voiding behavior of MSPG animals was similar to that in controls. Conclusions Intermittent bladder distention delays withdrawal of the spinal perigenital-bladder reflex but it does not affect maturation of the supraspinal bladder-bladder reflex that controls spontaneous voiding in older rats. This suggests that increased bladder afferent firing can selectively modulate spinal but not supraspinal mechanisms controlling postnatal changes in voiding function.

Wu, Hsi-Yang; de Groat, William C.

2011-01-01

224

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

225

The role of the superior laryngeal nerve in esophageal reflexes  

PubMed Central

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.

Medda, B. K.; Jadcherla, S.; Shaker, R.

2012-01-01

226

Driving a car using reflexive fuzzy behaviors  

SciTech Connect

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

Pin, F.G.; Watanabe, Y.

1992-10-01

227

Driving a car using reflexive fuzzy behaviors  

SciTech Connect

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

Pin, F.G.; Watanabe, Y.

1992-01-01

228

Gravity and Development of Cardiopulmonary Reflex  

NASA Astrophysics Data System (ADS)

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

Nagaoka, Shunji; Eno, Yuko; Ohira, Yoshinobu

229

Proprioceptive reaction times and long-latency reflexes in humans.  

PubMed

The stretch of upper limb muscles results in two electromyographic (EMG) peaks, M1 and M2. The amplitude of M2 peak can generally be modified by giving prior instruction to the subject on how to react to the applied perturbation. The unresolved question is whether the amplitude modulation results from change in the gain of the reflex pathway contributing to M2, or by superposition of reaction time (RT) activity. The following study attempted to resolve this question by examining the overlap between proprioceptive RT and M2 activities. Subject's right wrist flexors were stretched, and he/she was instructed either (1) not to intervene (passive task) or (2) to react as fast as possible by simultaneously flexing both wrists (active or compensate task). Under passive and active conditions, M1 and M2 were observed from EMG of right wrist flexors, and during the active condition, RT activities were additionally observed from both sides. The onset and offset of M2 (M1(onset), M2(offset)) were measured from the passive averages, while the RT was measured from the averaged EMG response of the left wrist flexors. For between-subject correlations, the data were divided into two sets: (1) subjects with RT shorter than M2(offset) (fast group) and (2) subjects with RT more than 10 ms longer than their M2(offset) (slow group). Modulation during M2 period was large for the fast group, and it was almost zero for the slow group. These results indicate that the superimposition of RT activity mainly contributes to the instruction-dependent modulation of M2 peak. PMID:22766848

Manning, C D; Tolhurst, S A; Bawa, P

2012-08-01

230

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

PubMed

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

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

2011-03-01

231

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

232

Plasticity of the human otolith-ocular reflex.  

PubMed

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. PMID:1441982

Wall, C; Smith, T R; Furman, J M

1992-01-01

233

Opioidergic inhibition of flexor and extensor reflexes in the rabbit.  

PubMed Central

1. Recordings were made from gastrocnemius medialis (GM), semitendinosus (ST) and tibialis anterior/extensor digitorum longus (TA/EDL) motor nerves during mechanical and electrical stimulation of the skin of the foot in decerebrated and spinalized rabbits. 2. GM motoneurones were excited from the heel and not from the toes, whereas TA/EDL responded to stimulation at the toes but not at the heel. ST also responded to electrical and mechanical stimulation at the toes, but there was a disparity between the effects of the two types of stimuli when they were applied at the heel: ST motoneurones fired in response to electrical stimulation of the heel but showed only an 'off' response to mechanical stimulation at this site. 3. The opioid antagonist naloxone caused a dose-dependent increase in all reflexes evoked by electrical stimulation of the skin. The heel-GM, toes-ST and toes-TA/EDL reflexes all increased to more than 3 times control levels with naloxone, which also caused significant decreases in the latencies of these reflex responses. On the other hand, the heel-ST response increased to just 1.4 times control levels and showed no decrease in latency with the opioid antagonist. 4. These data suggest that segmental withdrawal reflex pathways in the rabbit are suppressed by endogenous opioid peptides. This opioid-mediated inhibition seems to operate non-selectively on reflex pathways between cutaneous afferents and motoneurones.

Clarke, R W; Galloway, F J; Harris, J; Taylor, J S; Ford, T W

1992-01-01

234

Reflex control of inflammation by sympathetic nerves, not the vagus.  

PubMed

We investigated a neural reflex that controls the strength of inflammatory responses to immune challenge - the inflammatory reflex. In anaesthetized rats challenged with intravenous lipopolysaccharide (LPS, 60 ?g kg(-1)), we found strong increases in plasma levels of the key inflammatory mediator tumour necrosis factor ? (TNF?) 90 min later. Those levels were unaffected by previous bilateral cervical vagotomy, but were enhanced approximately 5-fold if the greater splanchnic sympathetic nerves had been cut. Sham surgery had no effect, and plasma corticosterone levels were unaffected by nerve sections, so could not explain this result. Electrophysiological recordings demonstrated that efferent neural activity in the splanchnic nerve and its splenic branch was strongly increased by LPS treatment. Splenic nerve activity was dependent on inputs from the splanchnic nerves: vagotomy had no effect on the activity in either nerve. Together, these data demonstrate that immune challenge with this dose of LPS activates a neural reflex that is powerful enough to cause an 80% suppression of the acute systemic inflammatory response. The efferent arm of this reflex is in the splanchnic sympathetic nerves, not the vagi as previously proposed. As with other physiological responses to immune challenge, the afferent pathway is presumptively humoral: the present data show that vagal afferents play no measurable part. Because inflammation sits at the gateway to immune responses, this reflex could play an important role in immune function as well as inflammatory diseases. PMID:24421357

Martelli, D; Yao, S T; McKinley, M J; McAllen, R M

2014-04-01

235

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.

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

2012-01-01

236

Human-like reflex control for an artificial hand.  

PubMed

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

Folgheraiter, Michele; Gini, Giuseppina

2004-01-01

237

Effects of postural changes of the upper limb on reflex transmission in the lower limb. Cervicolumbar reflex interactions in man.  

PubMed Central

The influence of passive changes in upper limb position on the excitability of three myotatic arc reflexes (soleus, quadriceps, and biceps femoris) of the lower limb has been explored on 42 volunteers. The results indicate that the excitability of the three myotatic arcs can be influenced at a distance by postural modifications of the upper limb. When the ipsilateral upper limb is forwards or the contralateral backwards, a facilitation of both soleus and quadriceps tendon reflexes is observed while the biceps femoris reflexes are reduced. This pattern of facilitation and inhibition is reversed when the ipsilateral upper limb is backwards or the contralateral forwards. The facilitations as well as inhibitions of proximal myotatic arc reflexes are quantitatively more marked than that of the soleus reflex. Facilitation and inhibition are not linearly related to the angle of the arm with the trunk. Effects begin at a considerable angle, become maximal at 45 degrees, and progressively disappear for greater values. It is suggested that the distinct pattern of facilitation and inhibition which is exerted in reciprocal fashion on extensor and flexor motor nuclei might depend on the long propriospinal neurones connecting cervical and lumbar enlargements.

Delwaide, P J; Figiel, C; Richelle, C

1977-01-01

238

Cardiac inhibitory reflex as a cause/mechanism of death.  

PubMed

The role of cardiac inhibitory reflex as a potential cause of death is still a matter of debate. This study reports two cases of death under unusual circumstances. Case 1 corresponds to a man found hanging where the role of ligature compression of the carotid sinus became relevant as a possible explanation of death. In Case 2, the participation of a vasovagal syncope was clearly triggered by the laryngoscopic procedure. It is proposed that cardiac inhibitory reflex should be taken into account in those cases of unexpected death, which fulfills the following three criteria: (i) The investigation of the circumstances of the death is consistent with a hypothesis of cardiac arrest. (ii) A typical triggering peripheral stimulus is present. (iii) The performance of a complete autopsy cannot rule out the participation of a cardiac inhibitory reflex in the cause of death. PMID:23786368

Suárez-Peñaranda, Jose M; Cordeiro, Cristina; Rodríguez-Calvo, Marisol; Vieira, Duarte N; Muñoz-Barús, Jose Ignacio

2013-11-01

239

Pain-related somatosensory evoked potentials in cortical reflex myoclonus.  

PubMed Central

To elucidate the sensitivity to pain stimuli in patients with cortical reflex myoclonus, pain-related somatosensory evoked potentials (pain SEPs) following CO2 laser stimulation and conventional electrically-stimulated SEPs (electric SEPs) were compared in four patients with cortical reflex myoclonus. The P25 peak of electric SEPs was considerably enhanced but the P320 potential of pain SEPs was of normal amplitude in all patients. After medication, myoclonus was reduced and the amplitude of P25 was decreased, but P320 showed no change. In our previous study of the scalp distribution in normal subjects, a subcortical site, probably the thalamus, was considered to be the generator source of P320. Because most pain stimuli do not reach the cortex, patients with cortical reflex myoclonus are not sensitive to pain stimuli and P320 in pain SEPs is not enhanced. Images

Kakigi, R; Shibasaki, H; Neshige, R; Ikeda, A; Mamiya, K; Kuroda, Y

1990-01-01

240

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.

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

241

Reflex anuria: a rare cause of acute kidney injury  

PubMed Central

Background Acute Kidney Injury results from pre renal, post renal or intrinsic renal causes. Reflex anuria is a very rare cause of renal impairment which happens due to irritation or trauma to one kidney or ureter, or severely painful stimuli to other nearby organs. Case Presentation Here we present a case of acute kidney injury secondary to reflex anuria in a patient who underwent extensive gynecological surgery along with ureteral manipulation which recovered spontaneously. Conclusion Reflex Anuria is a rare and often not considered as cause of acute kidney injury. This case illustrates that this should be kept as a differential in potential cause of acute kidney injury in patient undergoing urogenital or gynecological surgeries.

Adediran, Samuel; Dhakarwal, Pradeep

2014-01-01

242

Effect of a Muscle Relaxant on the Biomechanics of the Patella Reflex.  

National Technical Information Service (NTIS)

The thesis is on the development of a device and technique for the simple and direct measurement of the biomechanical parameters of reflex movements, such as displacement, velocity, and acceleration. The biomechanical profile of the patella reflex of heal...

R. K. Jarvik

1971-01-01

243

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

244

Choroidal blood flow. III. Reflexive control in human eyes.  

PubMed

Choroidal blood flow helps maintain a stable temperature environment for the outer retinal layers, especially in the macular area. Recent studies in monkeys have demonstrated a centrally mediated reflexive mechanism that increases choroidal blood flow in response to light or light-generated heat. This increase in choroidal blood flow can be detected as an elevation in ocular surface temperature. With the use of ocular surface temperature as a semiquantitative index of alterations in choroidal blood flow, the existence of a similar reflex was demonstrated in normal human volunteers. PMID:6626016

Parver, L M; Auker, C R; Carpenter, D O

1983-10-01

245

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.

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

2014-01-01

246

Electrical activation of the human vestibulo-sympathetic reflex.  

PubMed

Muscle sympathetic nerve activity (MSNA) is modulated on a beat-to-beat basis by the baroreflex. Vestibular input from the otolith organs also modulates MSNA, but characteristics of the vestibulo-sympathetic reflex (VSR) are largely unknown. The purpose of this study was to elicit the VSR with electrical stimulation to estimate its latency in generating MSNA. The vestibular nerves of seven subjects were stimulated across the mastoids with short trains of high frequency, constant current pulses. Pulse trains were delivered every fourth heartbeat at delays of 300-700 ms after the R wave of the electrocardiogram. Vestibular nerve stimulation given 500 ms after the R wave significantly increased baroreflex-driven MSNA, as well as the diastolic blood pressure threshold at which bursts of MSNA occurred. These changes were specific to beats in which vestibular stimulation was applied. Electrical stimulation across the shoulders provided a control condition. When trans-shoulder trials were subtracted from trials with vestibular nerve stimulation, eliminating the background baroreflex-driven sympathetic activity, there was a sharp increase in MSNA beginning 660 ms after the vestibular nerve stimulus and lasting for about 60 ms. The increase in the MSNA produced by vestibular nerve stimulation, and the associated increase in the diastolic blood pressure threshold at which the baroreflex-driven bursts occurred, provide evidence for the presence of a short-latency VSR in humans that is likely to be important for the maintenance of blood pressure during rapid changes in head and body position with respect to gravity. PMID:16308690

Voustianiouk, Andrei; Kaufmann, Horacio; Diedrich, André; Raphan, Theodore; Biaggioni, Italo; Macdougall, Hamish; Ogorodnikov, Dmitri; Cohen, Bernard

2006-05-01

247

Development of a data acquisition and analysis system for nociceptive withdrawal reflex and reflex receptive fields in humans.  

PubMed

A system for data acquisition and analysis of nociceptive withdrawal reflex (NWR) and reflex receptive field (RRF) is introduced. The system is constituted by hardware and software components. The hardware consists of devices commonly used for electrical stimulation and electromyographic and kinematic data recording. The software comprises two different programs: Wirex, a stand-alone program developed in LabView for data acquisition, and Reflex Lab, a Matlab-based toolbox for data analysis. These programs were developed to maximize the potential of the hardware, turning it into a complete stimulation system capable of automatic quantification of NWR and RRF. In this article, a brief review of NWR and RRF analysis is presented, the system features are described in detail and its present and future applications are discussed. PMID:21096727

Biurrun Manresa, Jose A; Hansen, John; Andersen, Ole K

2010-01-01

248

Three-dimensional vestibular eye and head reflexes of the chameleon: characteristics of gain and phase and effects of eye position on orientation of ocular rotation axes during stimulation in yaw direction.  

PubMed

We investigated gaze-stabilizing reflexes in the chameleon using the three-dimensional search-coil technique. Animals were rotated sinusoidally around an earth-vertical axis under head-fixed and head-free conditions, in the dark and in the light. Gain, phase and the influence of eye position on vestibulo-ocular reflex rotation axes were studied. During head-restrained stimulation in the dark, vestibulo-ocular reflex gaze gains were low (0.1-0.3) and phase lead decreased with increasing frequencies (from 100 degrees at 0.04 Hz to < 30 degrees at 1 Hz). Gaze gains were larger during stimulation in the light (0.1-0.8) with a smaller phase lead (< 30 degrees) and were close to unity during the head-free conditions (around 0.6 in the dark, around 0.8 in the light) with small phase leads. These results confirm earlier findings that chameleons have a low vestibulo-ocular reflex gain during head-fixed conditions and stimulation in the dark and higher gains during head-free stimulation in the light. Vestibulo-ocular reflex eye rotation axes were roughly aligned with the head's rotation axis and did not systematically tilt when the animals were looking eccentrically, up- or downward (as predicted by Listing's Law). Therefore, vestibulo-ocular reflex responses in the chameleon follow a strategy, which optimally stabilizes the entire retinal images, a result previously found in non-human primates. PMID:12783170

Haker, H; Misslisch, H; Ott, M; Frens, M A; Henn, V; Hess, K; Sándor, P S

2003-07-01

249

Reflex adrenergic inhibition of colonic motility in anesthetized rat caused by nociceptive stimuli of peritoneum  

Microsoft Academic Search

Nociceptive stimulation of the peritoneum inhibits colonic motility via a sympathoadrenergic reflex. This sympathetic reflex most probably induces the inhibition indirectly via a presynaptic blockade of cholinergic transmission. To further clarify this reflex, colonic motility was continuously recorded by a volume method in rats exposed to nociceptive abdominal stimulation and intravenous drug administration. Intraabdominally applied HCl inhibited colonic motility, which

Anders Sjöqvist; Bengt Hallerbäck; Hans Glise

1985-01-01

250

Design of a Reflex-Based Bidirectional Converter With the Energy Recovery Function  

Microsoft Academic Search

In this paper, a reflex charging strategy with the energy recovery function for a bidirectional converter (BC) is proposed to build a novel reflex-based BC (RBC) for increasing the battery charging efficiency in an uninterruptible power supply (UPS). The proposed RBC can provide a reflex charging current profile to charge the battery to obtain a high battery charging efficiency and

Liang-Rui Chen; Neng-Yi Chu; Chau-Shing Wang; Ruey-Hsun Liang

2008-01-01

251

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

252

Human interlimb reflexes evoked by electrical stimulation of cutaneous nerves innervating the hand and foot  

Microsoft Academic Search

There is some discrepancy over the extent to which reflex pathways from different cutaneous nerves in the hand and foot link the cervical and lumbar spinal cord in neurologically intact humans. The present experi- ments were designed to determine whether stimulation of a cutaneous nerve in the foot or in the hand evoked reflexes in the non-stimulated limbs (interlimb reflexes).

Paul Zehr; David F. Collins; Romeo Chua

2001-01-01

253

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

254

Differential modulation of withdrawal reflexes by a cannabinoid in the rabbit  

Microsoft Academic Search

Inhibition of spinal and trigeminal withdrawal reflexes by morphine and by the cannabinoid agonist HU 210 has been studied in anaesthetized and in decerebrated rabbits. In intact, pentobarbitone-anaesthetized animals, the jaw-depressor reflex (JDR) evoked by stimulation of the tongue, and the reflex elicited in the ankle flexor tibialis anterior (TA) by stimulation of the toes were inhibited to the same

Sarah Jenkins; Mark Worthington; John Harris; Rob W Clarke

2004-01-01

255

Abnormal blink reflex studies in a patient with supraorbital neuralgia.  

PubMed

A 44-year-old female with gabapentin-responsive supraorbital neuralgia is presented. She had pre- and post-treatment nociceptive-specific blink reflexes carried out which tracked the good clinical outcome from treatment. The results of the electrophysiological testing imply some central component to the pathophysiology of supra-orbital neuralgia. PMID:16776705

Cohen, A S; Gantenbein, A R; Goadsby, P J

2006-07-01

256

Abnormal Blink Reflex Studies in a Patient With Supraorbital Neuralgia  

Microsoft Academic Search

A 44-year-old female with gabapentin-responsive supraorbital neuralgia is presented. She had pre- and post-treatment nociceptive-specific blink reflexes carried out which tracked the good clinical outcome from treatment. The results of the electrophysiological testing imply some central component to the pathophysiology of supra-orbital neuralgia.

AS Cohen; AR Gantenbein; PJ Goadsby

2006-01-01

257

Minimum area polygons with two reflex angles enclosing k Points  

Microsoft Academic Search

We present in this paper, algorithms for finding the minimum area isothetic polygons having two reflex angles containing k points; (k

Kamala Krithivasan; Vanam Srilakshmi

2001-01-01

258

The Semantics of a Child's Use of Reflexives in Spanish.  

ERIC Educational Resources Information Center

A case study of the use of reflexive constructions by a Spanish-speaking child from age 2;5.2 to 3;5.2 is presented. Sixty hours of audiotaped utterances were recorded monthly over a one year period. The utterances are analyzed in terms of self-induced actions, impersonal constructions, and two-argument predicates. The data show the regular…

Pardo, Elly

259

Polyphony in the Classroom: Reporting Narrative Action Research Reflexively  

ERIC Educational Resources Information Center

In this article we will present a reflexive way of producing a narrative analysis on teaching and learning that involves all participants of the pedagogical process. Our theoretical contribution rests on the concept "lived pedagogy", adapted from Max van Manen's term "lived experience". Like van Manen, we start by asking the key question of…

Niemi, Reetta; Heikkinen, Hannu L. T.; Kannas, Lasse

2010-01-01

260

Muscle reflex in heart failure: the role of exercise training  

PubMed Central

Exercise evokes sympathetic activation and increases blood pressure and heart rate (HR). Two neural mechanisms that cause the exercise-induced increase in sympathetic discharge are central command and the exercise pressor reflex (EPR). The former suggests that a volitional signal emanating from central motor areas leads to increased sympathetic activation during exercise. The latter is a reflex originating in skeletal muscle which contributes significantly to the regulation of the cardiovascular and respiratory systems during exercise. The afferent arm of this reflex is composed of metabolically sensitive (predominantly group IV, C-fibers) and mechanically sensitive (predominately group III, A-delta fibers) afferent fibers. Activation of these receptors and their associated afferent fibers reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the sympathetic activation during exercise is exaggerated, which potentially increases cardiovascular risk and contributes to exercise intolerance during physical activity in chronic heart failure (CHF) patients. A therapeutic strategy for preventing or slowing the progression of the exaggerated EPR may be of benefit in CHF patients. Long-term exercise training (ExT), as a non-pharmacological treatment for CHF increases exercise capacity, reduces sympatho-excitation and improves cardiovascular function in CHF animals and patients. In this review, we will discuss the effects of ExT and the mechanisms that contribute to the exaggerated EPR in the CHF state.

Wang, Han-Jun; Zucker, Irving H.; Wang, Wei

2012-01-01

261

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

262

Vaginocavernosus reflex. Clinical significance and role in sexual act.  

PubMed

The action and clinical significance of the vaginocavernosus reflex was studied in 17 healthy women with a mean age of 36.6 years. The response of the bulbo- and ischiocavernosus muscles to rapid vaginal distension by balloon was recorded by a needle electrode inserted in each muscle and displayed on the screen of an EMG apparatus. The two cavernosus muscles contracted on vaginal distension; the amplitude of contraction increased with the increase of volume of vaginal inflation. The reflex contraction was not evoked after frequent successive or slow inflations or upon inflation of the anesthetized vagina. The latency of the reflex decreased with increased volume of vaginal inflation. The reflex cavernosus muscle contraction on vaginal distension during the sexual act seems to enhance both the clitoris and penile erection. This is believed to result from the compression exerted on both the deep dorsal vein of the penis and the erectile cavernous tissue. Also, cavernosus muscles contraction may help to milk the semen in the penile urethra into the vagina while the penis is being withdrawn from the vagina after ejaculation. Furthermore, vaginal distension by the fetal head during delivery induces cavernosus muscles contraction, which is suggested to support the head during its descent and prevent vaginal and perineal tears. PMID:8449442

Shafik, A

1993-01-01

263

Interlimb reflexes following cervical spinal cord injury in man  

Microsoft Academic Search

The reflex interconnection of lower and upper extremity muscles was investigated in subjects with chronic (> 1 year post-injury) lesions to the cervical spinal cord. Lower extremity mixed nerves were stimulated with single shocks or with brief trains of high-frequency stimuli of varying intensities. EMG from a number of lower and upper extremity muscles was recorded on magnetic tape for

B. Calancie

1991-01-01

264

Chronic Vestibulo-Ocular Reflexes Evoked by a Vestibular Prosthesis  

Microsoft Academic Search

We are developing prosthetics for patients suffering from peripheral vestibular dysfunction. We tested a sensory-replacement prosthesis that stimulates neurons innervating the vestibular system by providing chronic pulsatile stimulation to electrodes placed in monkeys' lateral semicircular canals, which were plugged bilaterally, and used head angular velocity to modulate the current pulse rate. As an encouraging finding, we observed vestibulo-ocular reflexes that

Daniel M. Merfeld; Csilla Haburcakova; Wangsong Gong; Richard F. Lewis

2007-01-01

265

Compartmentalization of the cervicocollic reflex in cat splenius muscle  

Microsoft Academic Search

We have examined the cervicocollic reflex (CCR), evoked by horizontal rotation of the head of decerebrate cats, in the dorsal neck extensor muscle splenius. This muscle is divided into compartments which are innervated by three or four spinal segments; an analogous Compartmentalization may be observed in the CCR.

K. Ezure; K. Fukushima; R. H. Schor; V. J. Wilson

1983-01-01

266

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

267

Carbon dioxide alters the Hoffmann reflex independent of hydrogen ions.  

PubMed

The purpose of this study was to examine the effect of changes in capillary blood pH on the resting soleus Hoffmann (H) reflex in the intact human. H-max size, H-wave at 20% of H-max, M-max and H-reflex latency were recorded in 10 subjects (apparently healthy, ages 19-36) before and after exposure to 3 hours of NaHCO3, CaCO3, NH4Cl (all at 0.3 g/kg) or 10 minutes 7% Carbon dioxide (CO2) administration. NaHCO3 increased capillary blood pH, CaCO3 did not change capillary blood pH, and NH4Cl and 7% CO2 decreased capillary blood pH. H-max and H-wave at 20% of M-max size were significantly decreased with no change in M-max, and H-reflex latency significantly increased during 7% CO2 administration only. No other changes in H-maximum size or H-reflex latency in response to dry chemical administration were observed. Seven percent CO2 administration reduces the size and increases the latency of the H-maximum size as previously found, but other chemicals which alter capillary blood pH do not. CO2 modulates afferent nerve function, and does so, it appears, independent of changes in capillary blood pH. PMID:24134189

Beekley, Matthew D

2014-07-01

268

Mechanism of Reflex Regulation of the Gastroduodenal Function by Acupuncture  

PubMed Central

Many clinical studies focus on the effects of acupuncture on digestive disorders. However, few studies describe the mechanism by which these effects are produced. We present some recent experimental work on the mechanism of acupuncture for reflex regulation of gastroduodenal function in anesthetized rats. In anesthetized rats, it has been proven that acupuncture to the abdomen excites sympathetic nerves via spinal reflexes causing inhibition of motilities while acupuncture of limbs excites vagus nerves via supraspinal reflexes causing an increase in the motilities. It has also been shown that in order to inhibit gastric motilities, acupuncture stimulation of the abdomen must be strong enough to excite group VI fibers of the afferent intercostal nerves. To increase gastric motilities, acupuncture stimulation to hind limbs must be strong enough to excite the high-threshold group III fibers of tibial nerves. It has also been shown that the neural mechanism of duodenal motility stimulation by acupuncture involves the same body regions and intensity of stimulation as that of gastric motilities. Theories regarding the underlying mechanism have proposed somato-autonomic reflexes and responses via endogenous opioids, etc., but without definitive conclusions.

2008-01-01

269

Hindlimb venous distention evokes a pressor reflex in decerebrated rats.  

PubMed

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

2014-06-01

270

Cutaneus trunci muscle reflex of the guinea pig.  

PubMed

The cutaneus trunci muscle reflex in guinea pigs was studied with a combination of video analysis, electromyography, lesioning, and light microscopy. The muscle forms a bilateral, subdermal sheet over much of the trunk. Local contractions of the dorsal part of the muscle are produced in response to brief tactile or electrical stimulation of the skin and consist of a twitch centered 1-2 cm rostral of the stimulus site. The reflex receptive field covers most of the thoracic and lumbar dorsal surface. The sensory information is carried via segmental dorsal cutaneous nerves. Receptive fields of adjacent nerves overlap and form rectangular areas perpendicular to the midline, at thoracic levels. Motor innervation projects through the lateral thoracic nerves of the brachial plexus. The motoneurons are located near the cervical thoracic junction (C7-T1). Lesions of the lower thoracic cord indicate that ascending sensory information is carried to the motor nuclei via the ventral half of the lateral funiculus. This pathway conveys information primarily from ipsilateral skin. There is a weaker input from contralateral skin, crossing at segmental levels. Electromyographic responses to brief electrical stimulation of lower thoracic skin occur usually as 10-12 msec bursts at latencies of 10-20 msec, and do not readily habituate or fatigue at stimulus frequencies below 10 Hz. The reflex persists under light pentobarbital anesthesia. This combination of characteristics makes the reflex useful for a variety of physiological and pathophysiological studies. PMID:2358554

Blight, A R; McGinnis, M E; Borgens, R B

1990-06-22

271

Opening to Possibility: Reflectivity and Reflexivity in Our Teaching  

ERIC Educational Resources Information Center

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

Wilhelm, Jeff, Ed.

2013-01-01

272

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

273

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

274

Triangulations, Visibility Graph and Reflex Vertices of a Simple Polygon  

Microsoft Academic Search

In this paper tight lower and upper bounds for the number of triangulations of a simple polygon are obtained as a function of the number of reflex vertices, thus relating these two shape descriptors. Tight bounds for the size of the visibility graph of a polygon are obtained too, with the same parameter. The former bounds are also studied from

Ferran Hurtado; Marc Noy

1996-01-01

275

Reflex Activity in Spinal Cats with Postasphyxial Rigidity.  

National Technical Information Service (NTIS)

The reflex activity in three groups of cats in which the spinal cord had been asphyxiated for 30 to 55 min, and which had been kept from one day to 2 weeks afterwards was compared with that in acute and chronic spinal control animals. Asphyxiation tended ...

A. V. Harreveld D. Spinelli

1964-01-01

276

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.

Abdala, Carolina; Mishra, Srikanta; Garinis, Angela

2013-01-01

277

Postoperative Pain and Superficial Abdominal Reflexes After Posterolateral Thoracotomy  

Microsoft Academic Search

Background. Posterolateral thoracotomy can produce stretching of\\/or damage to the intercostal nerves and their branches. To assess intercostal nerve impairment after operation, we measured the superficial abdominal reflexes, which are mediated, at least in part, by the most inferior intercostal nerves.Methods. Using electrophysiologic techniques, we made recordings from the left and right abdominal walls to study the responses evoked by

Fabrizio Benedetti; Martina Amanzio; Caterina Casadio; Pier Luigi Filosso; Massimo Molinatti; Alberto Oliaro; Franco Pischedda; Giuliano Maggi

1997-01-01

278

Pure nuclear reflexes and combined hyperfine interactions in YIG  

Microsoft Academic Search

Mössbauer spectra of oriented YIG single crystals were taken and the numerical analysis using the transmission integral yielded a consistent set of hyperfine interaction parameters. They are in good agreement with theoretical values obtained by MO-calculations which included clusters up to 62 ions. Finally pure nuclear reflexes are predicted for single crystals and two theoretical spectra are given.

H. Winkler; R. Eisberg; E. Alp; R. Rüffer; E. Gerdau; S. Lauer; A. X. Trautwein; M. Grodzicki; A. Vera

1983-01-01

279

Computer Model for a Controller System of Spinal Reflex Patterns  

Microsoft Academic Search

Nervous system presents the grey and the white matter. The c ord g rey matter is the integrative area for the spinal reflexes and o ther motor f unctions. Sensory signals enter the c ord through the sensory nerve roots, and after they have two d ifferent destinations: (a) the grey matter of the cord, where some sensory fibre or

Frederico A. O. Cruz; Célia M. Cortez

280

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

PubMed Central

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

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

2001-01-01

281

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

282

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

283

Changes in perceived heaviness and motor commands produced by cutaneous reflexes in man.  

PubMed Central

1. This study examined the relationship between the perceived heaviness of a weight and reflexes acting on the motoneurones required for the contraction. The perceived heaviness of low (100 g) and high (500 g) reference weights lifted by the first dorsal interosseous muscle was estimated using a matching task. Weights were also lifted during stimulation of the digital nerves of the index finger at two times and four times sensory threshold (T). Averages of force and EMG were also made when isometric forces of 100 and 500 g were maintained. 2. Stimuli at 4T produced a significant increase in perceived heaviness in each subject for both reference weights. Averages of EMG made under isometric conditions showed a short-latency inhibition with a reflex reduction in force following single stimuli. This inhibition was also observed during weight lifting when trains of stimuli were given. 3. Stimuli at 2T produced less-marked changes in EMG, averaged force, and perceived heaviness for individual subjects. However, for the group of subjects, perceived heaviness declined significantly with 2T stimuli for the 500 g but not the 100 g weight. This decrease in perceived heaviness was associated with evidence of short-latency facilitation within the motoneurone pool. 4. Inhibition of the motoneurone pool was associated with an increase and facilitation with a decrease in perceived heaviness. These observations favour a role for a signal of centrally generated motor command in the sensation of heaviness and provide insight as to how this signal must change when reflex inputs change and when high-threshold motoneurones are recruited.

Aniss, A M; Gandevia, S C; Milne, R J

1988-01-01

284

Function of sural nerve reflexes during human walking  

PubMed Central

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

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

1998-01-01

285

The REFLEX II galaxy cluster survey: power spectrum analysis  

NASA Astrophysics Data System (ADS)

We present the power spectrum of galaxy clusters measured from the new ROSAT-ESO Flux-Limited X-Ray (REFLEX II) galaxy cluster catalogue. This new sample extends the flux limit of the original REFLEX catalogue to 1.8 × 10-12 erg s-1 cm-2, yielding a total of 911 clusters with ?94 per cent completeness in redshift follow-up. The analysis of the data is improved by creating a set of 100 REFLEX II-catalogue-like mock galaxy cluster catalogues built from a suite of large-volume ? cold dark matter (?CDM) N-body simulations (L-BASICC II). The measured power spectrum is in agreement with the predictions from a ?CDM cosmological model. The measurements show the expected increase in the amplitude of the power spectrum with increasing X-ray luminosity. On large scales, we show that the shape of the measured power spectrum is compatible with a scale-independent bias and provide a model for the amplitude that allows us to connect our measurements with a cosmological model. By implementing a luminosity-dependent power-spectrum estimator, we observe that the power spectrum measured from the REFLEX II sample is weakly affected by flux-selection effects. The shape of the measured power spectrum is compatible with a featureless power spectrum on scales k > 0.01 h Mpc-1 and hence no statistically significant signal of baryonic acoustic oscillations can be detected. We show that the measured REFLEX II power spectrum displays signatures of non-linear evolution.

Balaguera-Antolínez, A.; Sánchez, Ariel G.; Böhringer, H.; Collins, C.; Guzzo, L.; Phleps, S.

2011-05-01

286

Self-protective whole body motion for humanoid robots based on synergy of global reaction and local reflex.  

PubMed

This paper describes a self-protective whole body motor controller to enable life-long learning of humanoid robots. In order to reduce the damages on robots caused by physical interaction such as obstacle collision, we introduce self-protective behaviors based on the adaptive coordination of full-body global reactions and local limb reflexes. Global reactions aim at adaptive whole-body movements to prepare for harmful situations. The system incrementally learns a more effective association of the states and global reactions. Local reflexes based on a force-torque sensing function to reduce the impact load on the limbs independently of high-level motor intention. We examined the proposed method with a robot simulator in various conditions. We then applied the systems on a real humanoid robot. PMID:22377658

Shimizu, Toshihiko; Saegusa, Ryo; Ikemoto, Shuhei; Ishiguro, Hiroshi; Metta, Giorgio

2012-08-01

287

Convergence in segmental reflex pathways from nociceptive and non-nociceptive afferents to alpha-motoneurones in the cat.  

PubMed Central

1. Reflex interaction between nociceptive and non-nociceptive segmental afferents was investigated by testing for spatial facilitation of postsynaptic potentials (PSPs) in alpha-motoneurones recorded in anaemically decapitated, high spinal cats. Nociceptive segmental afferents were activated by applying noxious radiant heat to the skin. Non-nociceptive skin mechanoreceptors were activated by puffs of air. Non-nociceptive skin, joint and group I-III muscle afferents were stimulated by electrical pulses delivered to various nerves. 2. Conditioning by stimulation of nociceptive afferents facilitated transmission in various ipsilateral segmental pathways. Such spatial facilitation occurred in both excitatory and inhibitory pathways. Pathways that were facilitated included those activated by low to medium threshold cutaneous afferents, joint afferents, and group Ib and II muscle afferents. 3. In contrast, monosynaptic EPSPs evoked by stimulating ipsilateral group Ia muscle afferents did not show spatial facilitation but rather inhibition during conditioning stimulation of nociceptive afferents. Spatial facilitation of reciprocal group Ia IPSPs was rare and small if it occurred. 4. Pathways activated by cutaneous and group II muscle afferents were depressed by contralateral stimulation of nociceptive afferents. 5. We conclude that spatial facilitation observed between nociceptive and non-nociceptive afferents results from a convergence of inputs on common interneurones in the reflex pathways to alpha-motoneurones. Therefore nociceptive afferents have to be regarded as constituents of flexor reflex afferents (FRAs) and may add a specific nocifensive function to the FRA system.

Steffens, H; Schomburg, E D

1993-01-01

288

The Motor Present State in Man under Water Immersion Conditions.  

National Technical Information Service (NTIS)

The functional state of the segmental apparatus before voluntary movement was investigated in subjects under water immersion conditions. The H-reflex was used to evaluate the excitability of the spinal cord motoneurons. On the third, fourth, and fifth day...

A. V. Ovsyannikov

1974-01-01

289

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

PubMed Central

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

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

2013-01-01

290

Altered gravitational experience during early periods of life affects the static vestibulo-ocular reflex of tadpoles of the Southern Clawed Toad, Xenopus laevis Daudin  

Microsoft Academic Search

The effects of altered gravitational forces (AGF) on the development of the static vestibulo-ocular reflex (VOR) were investigated in Xenopus laevis tadpoles exposed to hypergravity (1.4g; 3g) or microgravity conditions (German spacelab mission D-2) for 9–10 days. The effects of light conditions during development were also tested by exposing tadpoles to either complete darkness (DD) or 12:12 h light-dark conditions

C. Sebastian; K. Eßeling; E. Horn

1996-01-01

291

Inappropriate mediastinal baroreceptor reflex as a possible cause of sudden infant death syndrome - Is thorough burping before sleep protective?  

PubMed

Despite extensive research, a link between the assumed mechanisms of death and known risk factors for sudden infant death syndrome (SIDS) has not yet been established. Modifiable risk factors such as prone sleeping position, nicotine exposure and thermal stress and non-avoidable risk factors like male gender and some risky socio-economic conditions could be detected, but the etiology of SIDS remains unknown. In many SIDS cases histopathological findings suggest an involvement of vital autonomic control functions and unidentified trigger factors seem to play a role. From a hypothetical point of view, a developmental sympatheticovagal imbalance of the cardiovascular reflex control could cause a predisposition for SIDS. An assumed gastroesophageal trigger impulse is possibly developed during the first weeks of life and could lead to the infant's vagal reflex death. Air swallowed during feeding escapes through the esophagus while the infant is sleeping. The temporarily bloated esophagus exerts pressure on neighboring mediastinal baroreceptors, which is potentially misinterpreted as a rise in arterial pressure. The following cardiodepressoric baroreceptor reflex could lead to arterial hypotension, bradycardia and cardiac arrest. Sleeping in prone position may create an increased thoracic pressure on mediastinal baroreceptors, causing a more pronounced vagal reflex and an increased likelihood of SIDS. Prone position in connection with soft objects in the infant's sleeping environment potentially generates an increased oculobulbar pressure, resulting in an additional cardiodepressoric condition (Aschner-Dagnini phenomenon). From the sixth month of life onwards the sympatheticovagal balance seems to have matured sufficiently to compensate the life-threatening challenges in most infants. Insufficient postprandial burping could either create another independent modifiable risk factor or present the missing link to a common trigger mechanism for SIDS. Further investigations may possibly lead to the explicit recommendation to burp all infants sufficiently and repeatedly before sleep. PMID:17145140

Flaig, Christian

2007-01-01

292

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

PubMed

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

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

2011-01-01

293

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.

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

2014-01-01

294

The role of periodontal receptors in the jaw-opening reflex in the cat.  

PubMed Central

1. In anaesthetized cats, graded electrical stimulation of the inferior alveolar nerve at just above threshold for the largest afferent fibres caused inhibition of jaw-closer motoneurones. Stimulus strength had to be increased to 1.5 times threshold with double shocks to cause reflex contraction of the digastric muscle. 2. Inhibition of jaw-closer muscles and excitation of digastric muscle resulted from transients of force applied to the upper canine tooth. However, the threshold for the digastric response was approximately 11 times higher than that of the periodontal afferent units recorded in the mesencephalic nucleus of the fifth nerve (MesV). Vibration of the upper canine at 50 Hz, with amplitude adequate to excite periodontal afferents, caused no digastric contraction. 3. Stimulation in the caudal part of the MesV so as to excite periodontal afferents caused no digastric reflex, provided that the stimulus did not spread to other parts of the fifth nerve nuclei. 4. It is concluded that under these conditions the low-threshold periodontal mechanoreceptors cause inhibition of jaw-closer muscles, but no significant excitation of jaw-opener muscles. 5. These findings are discussed from the point of view of the control which periodontal mechanoreceptors may exert over the biting force during mastication.

Dessem, D; Iyadurai, O D; Taylor, A

1988-01-01

295

Acute myocardial ischemia enhances the vanilloid TRPV1 and serotonin 5-HT3 receptor-mediated Bezold-Jarisch reflex in rats.  

PubMed

The Bezold-Jarisch reflex is characterized by a sudden bradycardia associated with hypotension induced by the activation of the vanilloid TRPV1 and serotonin 5-HT(3) receptors. This reflex is associated with several health conditions, including myocardial infarction. The aim of the present study was to elucidate the influence of acute experimental myocardial ischemia on the reflex bradycardia induced by anandamide and phenylbiguanide, agonists of the TRPV1 and 5-HT(3) receptors, respectively. In urethane-anesthetized rats, the rapid iv injection of anandamide (0.6 ?mol/kg) or phenylbiguanide (0.03 ?mol/kg) decreased heart rate (HR) by about 7-10% of the basal values. Myocardial ischemia (MI) was induced by ligation of the left anterior coronary artery. The agonists were injected 5 min before MI (S(1)) and 10, 20 and 30 min thereafter (S(2)-S(4)). MI potentiated the anandamide-induced reflex bradycardia by approximately 105% at S(2) and 70% at S(3) but had no effect at S(4). This amplificatory effect of MI was virtually abolished by the TRPV1 receptor antagonist capsazepine (1 ?mol/kg) and was not modified by the cannabinoid CB(1) receptor antagonist rimonabant (0.1 ?mol/kg). MI also amplified the reflex bradycardia elicited by phenylbiguanide by approximately 110, 60 and 90% (S(2), S(3) and S(4), respectively), and this effect was sensitive to the 5-HT(3) receptor antagonist ondansetron (3 ?mol/kg). In conclusion, our results suggest that acute myocardial ischemia augments the Bezold-Jarisch reflex induced via activation of TRPV1 and 5-HT(3) receptors located on sensory vagal nerves in the heart. PMID:22358093

Lupi?ski, Sebastian ?; Schlicker, Eberhard; P?dzi?ska-Betiuk, Anna; Malinowska, Barbara

2011-01-01

296

Bulbar inhibition of spinal and supraspinal sympathetic reflex discharges  

Microsoft Academic Search

Summary  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a In chloralose anesthetized cats, the sympathetic reflex discharge was recorded from the renal sympathetic nerve.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a The early-spinal and late-supraspinal sympathetic reflex discharges were elicited by single electrical stimulation of the\\u000a thoracic dorsal roots.\\u000a \\u000a \\u000a \\u000a \\u000a 3. \\u000a \\u000a Increased excitation of the baroceptor afferents produced by a rise of blood pressure after injection of noradrenaline caused\\u000a strong inhibitition of the latesupraspinal

F. Kirchner; A. Sato; H. Weidinger

1971-01-01

297

Supratentorial Multiple Sclerosis Lesions Affect the Blink Reflex Test  

PubMed Central

Introduction The Blink Reflex Test (BRT) is a neurophysiological examination used for evaluation of brainstem reflex circuits. MRI is the most precise modality for evaluation of MS lesion anatomy. Our study objective was to investigate how the functional results of the neurophysiological BRT relate to the anatomy of MS lesions in routine MRI studies. Methods 65 MS patients underwent the BRT within 2 months of a brain MRI showing demyelinating lesions. Results The overall sensitivity of the BRT was 90.8%, while in patients with at least one brainstem lesion and no brainstem lesions it was 91.4% and 90%, respectively. Discussion The presence of brainstem lesions does not significantly affect BRT sensitivity. This points to the influence of supratentorial MS lesions on the BRT. Gender, age, disease duration, type of MS, acuteness of an MS event and whether MS diagnosis was recent or not were not variables affecting the results.

Mikropoulos, Efthimios H; Papathanasiou, Afroditi A; Hadjigeorgiou, Georgios; Tsironi, Evangelia; Papadimitriou, Alex

2010-01-01

298

Reflex myoclonic epilepsy in infancy: a critical review.  

PubMed

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

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

2013-06-01

299

Frequency tuning of the contralateral medial olivocochlear reflex in humans  

PubMed Central

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

Dhar, Sumitrajit

2012-01-01

300

Network Activity in Neurons of the Motor and Prefrontal Areas of the Cortex in Trained Cats in Conditions of Systemic Administration of m-Cholinoreceptor Blockers  

Microsoft Academic Search

Experiments on five cats already trained to an operant conditioned food-procuring reflex to light were used to study the network activity of cells in the frontal and motor areas of the cortex accompanying disruption of conditioned reflex behavior in conditions of systemic administration of m-cholinoreceptor blockers. The activity of cortical neurons and their network properties were assessed using auto- and

V. N. Khokhlova; G. Kh. Merzhanova; É. E. Dolbakyan

2002-01-01

301

Increased Auditory Startle Reflex in Children with Functional Abdominal Pain  

Microsoft Academic Search

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

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

2010-01-01

302

Electrical activation of the human vestibulo-sympathetic reflex  

Microsoft Academic Search

Muscle sympathetic nerve activity (MSNA) is modulated on a beat-to-beat basis by the baroreflex. Vestibular input from the otolith organs also modulates MSNA, but characteristics of the vestibulo-sympathetic reflex (VSR) are largely unknown. The purpose of this study was to elicit the VSR with electrical stimulation to estimate its latency in generating MSNA. The vestibular nerves of seven subjects were

Andrei Voustianiouk; Horacio Kaufmann; André Diedrich; Theodore Raphan; Italo Biaggioni; Hamish MacDougall; Dmitri Ogorodnikov; Bernard Cohen

2006-01-01

303

Does peri-operative guanethidine prevent reflex sympathetic dystrophy?  

Microsoft Academic Search

The use of intravenous guanethidine blocks is an accepted treatment for established reflex sympathetic dystrophy (RSD). Some units administer intravenous guanethidine peri-operatively with the intention of protecting their patients from post-operative dystrophy. There have been no studies confirming this protective effect of peri-operative guanethidine. Between 1992 and 1994 we performed a prospective randomized double blind study in 71 patients undergoing

C. Gschwind; R. Fricker; G. Lacher; M. Jung

1995-01-01

304

Central integration of swallow and airway protective reflexes  

Microsoft Academic Search

The relationship between the timing of respiration and swallowing has been proven not to be random. Using pseudorabies virus (PRV) as a transsynaptic neural tracer, a basis for the central integration of swallowing and airway-protective reflexes can be located in the neural circuits projecting to swallowing-related muscles.The premotor neurons (PMNs) that constitute the swallowing central pattern generators, interneuronal networks able

Delma L Broussard; Steven M Altschuler

2000-01-01

305

Conducting systematic review in education: a reflexive narrative  

Microsoft Academic Search

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

Melanie Nind

2006-01-01

306

Neuronal pathways for the lingual reflex in the Japanese toad  

Microsoft Academic Search

1.Anuran tongue is controlled by visual stimuli for releasing the prey-catching behavior (‘snapping’) and also by the intra-oral stimuli for eliciting the lingual reflex. To elucidate the neural mechanisms controlling tongue movements, we analyzed the neuronal pathways from the glossopharyngeal (IX) afferents to the hypoglossal (XII) tongue-muscle motoneurons.2.Field potentials were recorded from the bulbar dorsal surface over the fasciculus solitarius

Toshiya Matsushima; Masahiko Satou; Kazuo Ueda

1988-01-01

307

Masseteric silent period and reflex before and after dentomaxillofacial surgery  

Microsoft Academic Search

.   The aim of this study was to evaluate massetteric silent period and reflex in patients affected by progenia, before and after\\u000a maxillofacial surgery, in order to determine their clinical utility. The electrophysiological changes generated by malocclusion\\u000a secondary to prognatism have been evaluated before and after maxillofacial corrective surgery in 14 patients aged between\\u000a 18 and 36 years. The masseteric

B. Jandolo; E. Galiè; D. Badia

2003-01-01

308

Relationship of cat vestibular neurons to otolith-spinal reflexes  

Microsoft Academic Search

Summary  The dynamics of neurons in the vestibular nuclei of canal-plugged, decerebrate cats were studied in response to lateral (roll) tilt. Forelimb and neck extensor reflexes recorded simultaneously develop a progressive phase lag above 0.1 Hz. Neurons which exhibited a muscle-like phase lag were excited during low frequency stimuli by ipsilateral side-up tilt (beta response). Neurons with alpha responses, excited during

R. H. Schor; A. D. Miller

1982-01-01

309

Acceptance of the different denominations for reflex sympathetic dystrophy  

Microsoft Academic Search

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

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

2001-01-01

310

The carotid sinus baroreceptor reflex in conscious rabbits.  

PubMed Central

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

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

1980-01-01

311

Effect of smoking cessation on cough reflex sensitivity.  

PubMed

Recent studies have shown that cigarette smokers have diminished cough reflex sensitivity compared with nonsmokers. The current authors proposed a mechanism of chronic cigarette smoke-induced desensitisation of airway cough receptors. To investigate this hypothesis, cough sensitivity to inhaled capsaicin (C5) in chronic smokers was measured both while they were actively smoking and 2, 6, 12 and 24 weeks after smoking cessation. In total, 29 subjects underwent baseline capsaicin challenge while smoking and 2 weeks after smoking cessation. Mean+/-sem log C5 fell from 1.86+/-0.12 to 1.60+/-0.12, demonstrating significant enhancement of cough reflex sensitivity. Of the total, 20, 18 and 14 subjects successfully abstained from smoking for 6, 12 and 24 weeks, respectively. Mean log C5 values after 12 and 24 weeks of smoking cessation were significantly diminished from baseline. In a control group of smokers, mean log C5 did not decrease from baseline after 6, 12 and 24 weeks. Overall, the log C5 profile of the smoking cessation group showed a clear, linearly decreasing trend over time compared with the control group. Even after many years of smoking, cough sensitivity is enhanced as early as 2 weeks after smoking cessation. Given the importance of an intact cough reflex, these changes may provide clinical benefit. PMID:16774954

Dicpinigaitis, P V; Sitkauskiene, B; Stravinskaite, K; Appel, D W; Negassa, A; Sakalauskas, R

2006-10-01

312

Primitive reflexes in amyotrophic lateral sclerosis: prevalence and correlates.  

PubMed

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

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

2014-06-01

313

Interaction of tonic neck and vestibular reflexes in the forelimb of the decerebrate cat  

Microsoft Academic Search

Summary  Tonic neck reflexes, studied with EMG recording, have similar dynamics in forelimb extensor muscles of acutely labyrinthectomized cats, and in cats with intact labyrinths. The reflex occurs more frequently in the latter and its gain is higher. In intact preparations we evoked vestibular and tonic neck reflexes separately or in combination, at frequencies of 0.05–0.5 Hz. As expected from earlier

K. Ezure; V. J. Wilson

1984-01-01

314

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

PubMed Central

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

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

2013-01-01

315

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

316

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

Microsoft Academic Search

Changes in the activity of human jaw-elevator muscles related to the mandibular stretch (jaw-jerk) reflex could be involved in the aetiology of temporomandibular disorders (TMD). In order to investigate whether there are differences in the sensitivity of the jaw-jerk reflex between myogenous TMD patients (n = 10) and gender- and age-matched controls (n = 10), jaw-jerk reflexes were elicited under

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

1996-01-01

317

Cannabinoidergic and opioidergic inhibition of spinal reflexes in the decerebrated, spinalized rabbit  

Microsoft Academic Search

The present experiments were designed to investigate the role(s) of cannabinoid receptors in modulating transmission in the sural–medial gastrocnemius withdrawal reflex of the decerebrated, spinalized rabbit and how, if present, cannabinoid-mediated control might interact with opioid-mediated inhibitions known to impinge on this reflex pathway. The selective CB1 receptor antagonist SR 141716A enhanced reflexes by a factor of two after a

R. W Clarke; J Harris; S Jenkins; S. K Witton

2001-01-01

318

Centrally-generated and reflexive control strategies in the adaptive behavior of real and simulated animals  

Microsoft Academic Search

In our studies of the odor-guided navigation of real and simulated insects we have explicitly addressed the strengths and weaknesses of reflexive and centrally-patterned control strategies in successfully adapting to a complex environment. While often presented as contesting organizational principles, reflexive and centrally-patterned behaviors actually exist on a continuum ranging from purely reflexive control with no central contribution to purely

Jim H. Belanger; Mark A. Willis

319

A Conserved Network for Control of Arthropod Exteroceptive Optical Flow Reflexes during Locomotion  

Microsoft Academic Search

\\u000a We have developed an exteroceptive reflex network of sensory interneurons and command neurons that simulates arthropod optical\\u000a reflexes based on current ethological and neurophysiological models. The simple neural network was instantiated in software\\u000a with discrete-time map-based neurons and synapses and can mediate four forms of optomotor reflexes in arthropods: (1) translational\\u000a responses to pure translational optic flow; (2) rotational responses

Daniel Blustein; Joseph Ayers

2010-01-01

320

Withdrawal reflexes in adductor muscles elicited by electrical and magnetic stimulation of the obturator nerve.  

PubMed

The withdrawal reflex in the short head of the biceps femoris muscle after electrical stimulation of the sural nerve at the ankle has been investigated in numerous studies. These studies have described two distinct responses: early (R-II) and late (R-III). However, withdrawal reflex activity of the adductor muscles in the legs has not been studied systematically. Adductor muscle reflex activity is important because it can produce serious clinical problems, such as adductor spasticity and spasms, during bladder surgery. The present study examined withdrawal reflex features of adductor muscles obtained by electrical and magnetic stimulation of the obturator nerve (ON) in 34 normal healthy subjects. Early adductor muscle withdrawal reflex responses were elicited by ipsilateral ON electrical stimulation with a mean latency of 45.7+/-2.0 ms (responses in 94% of subjects). Reflex responses were also obtained using magnetic stimulation at a similar incidence rate. Contralateral ON electrical stimulation resulted in a similar reflex, but with a lower incidence. ON and femoral nerve electrical and magnetic coil stimulation produced similar low-incidence responses in the vastus medialis. These findings indicate that short latency adductor withdrawal reflexes are easily obtained on both sides following electrical or magnetic stimulation of the ON, and they can be elicited by both nociceptive and nonnociceptive stimuli. These reflexes prepare the body for a proper response to incoming signals and likely serve to protect the pelvic floor and pelvic organs. PMID:18816621

Ertekin, Cumhur; Bademkiran, Fikret; Yalin, Sevket; Karapinar, Nevin; Uysal, Hilmi

2008-11-01

321

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

PubMed Central

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

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

2013-01-01

322

Antinociceptive effect of R-(+)-hyoscyamine on the conjunctival reflex test in rabbits.  

PubMed

R-(+)-Hyoscyamine (1-10 microg/kg, s.c.) dose-dependently increased the local anesthetic effect of procaine (50 microg/ml) and lidocaine (50 microg/ml) in the conjunctival reflex test in the rabbit. This potentiating effect is completely prevented by the M1 antagonist dicyclomine (10 mg/kg, s.c.). The intensity of R-(+)-hyoscyamine antinociception was comparable to that induced by morphine (2 mg/kg, s.c.) and minaprine (15 mg/kg, s.c.), used as analgesic reference drugs. In the same experimental conditions, the S-(-)-enantiomer of atropine (0.1-10 microg/kg, s.c.), was completely ineffective. The present results confirm the ability of R-(+)-hyoscyamine to produce a paradoxical antinociceptive effect mediated by a cholinergic mechanism not only in rodents but also in the rabbit. PMID:10580368

Ghelardini, C; Galeotti, N; Fantetti, L; Gualtieri, F; Scapecchi, S; Bartolini, A

1999-09-01

323

Noise-induced intermittency of a reflexive model with symmetry-induced equilibrium manifold  

NASA Astrophysics Data System (ADS)

We discuss a route to intermittency based on the concept of reflexivity, namely on the interaction between observer and stochastic reality. A simple model mirroring the essential aspects of this interaction is shown to generate perennial out of equilibrium condition, intermittency and 1/f-noise. In the absence of noise the model yields a symmetry-induced equilibrium manifold with two stable states. Noise makes this equilibrium manifold unstable, with an escape rate becoming lower and lower upon time increase, thereby generating an inverse power law distribution of waiting times. The distribution of the times of permanence in the basin of attraction of the equilibrium manifold are analytically predicted through the adoption of a first-passage time technique. Finally we discuss the possible extension of our approach to deal with the intermittency of complex systems in different fields.

Palatella, Luigi; Grigolini, Paolo

2012-12-01

324

Simultaneously measured pupillary light reflex and heart rate variability in healthy children  

PubMed Central

We investigated the potential interrelationship between two measures of autonomic nervous system: pupillary light reflex (PLR) and heart rate variability (HRV), in healthy children of 8–16 years old. PLR was measured at both dark- and light-adapted conditions with various stimulation intensities. Simultaneously measured HRV was obtained in five different PLR testing phases: before PLR test, light-adapted PLR test, dark adaptation, dark-adapted PLR test, and after PLR test. The frequency domain HRV parameters measured during PLR test were significantly different from those measured during rest. Both regression analysis and factor analysis indicated that PLR and HRV parameters were not correlated, which suggests that they may provide complementary assessment of different aspects of the overall autonomic nervous system.

Daluwatte, C; Miles, J H; Yao, G

2012-01-01

325

Reflex sympathetic dystrophy and repetitive strain injury: temperature and microcirculatory changes following mild cold stress.  

PubMed Central

Temperature and blood flow studies were performed in the upper limbs of six patients with reflex sympathetic dystrophy (RSD), nine patients with repetitive strain injury (RSI) and 12 control subjects using thermography, laser Doppler flowmetry, infrared photoplethysmography and venous occlusion strain gauge plethysmography. The contralateral responses of the symptomatic and asymptomatic limbs were examined after being subjected, separately, to mild cold stress (20 degrees C for 1 min). Altered thermoregulation and haemodynamics were evident in RSD. Though the pattern of response to contralateral cold challenge is similar to normal in RSI, vasodilatation and reduced vasomotion appears to be characteristic in this condition. Such changes may assist in distinguishing between RSD and RSI from other causes of chronic upper limb pain.

Cooke, E D; Steinberg, M D; Pearson, R M; Fleming, C E; Toms, S L; Elusade, J A

1993-01-01

326

Abnormalities of the blink reflex in Gilles de la Tourette syndrome.  

PubMed Central

The blink reflex and it's recovery cycle were studied in 26 patients with Gilles de la Tourette syndrome and 10 controls. There was a significant increase in the mean duration of the R2 response. The amplitude of the R2 response following paired shocks (mean R2[T]/R2[C]%) was 11%, 40% and 52% of the conditioning stimulus with intervals of 200 ms, 500 ms and 1 second in the patients, compared with 10%, 17% and 32% respectively in the controls. Half the patients, however, had normal recovery cycles and voluntary suppression of tics and blinks reduced the amplitude of R2 in all patients. These results suggest increased excitability of brainstem interneurons in Gilles de la Tourette syndrome.

Smith, S J; Lees, A J

1989-01-01

327

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

328

The effect of transcranial magnetic stimulation on the soleus H reflex during human walking  

PubMed Central

The effect of transcranial magnetic stimulation (TMS) on the soleus H reflex was investigated in the stance phase of walking in seventeen human subjects. For comparison, measurements were also made during quiet standing, matched tonic plantar flexion and matched dynamic plantar flexion.During walking and dynamic plantar flexion subliminal (0.95 times threshold for a motor response in the soleus muscle) TMS evoked a large short-latency facilitation (onset at conditioning-test interval: ?5 to ?1 ms) of the H reflex followed by a later (onset at conditioning-test interval: 3–16 ms) long-lasting inhibition. In contrast, during standing and tonic plantar flexion the short-latency facilitation was either absent or small and the late inhibition was replaced by a long-lasting facilitation.When grading the intensity of TMS it was found that the short-latency facilitation had a lower threshold during walking than during standing and tonic plantar flexion. Regardless of the stimulus intensity the late facilitation was never seen during walking and dynamic plantar flexion and the late inhibition was not seen, except for one subject, during standing and tonic plantar flexion.A similar difference in the threshold of the short-latency facilitation between walking and standing was not observed when the magnetic stimulation was replaced by transcranial electrical stimulation.The lower threshold of the short-latency facilitation evoked by magnetic but not electrical transcranial stimulation during walking compared with standing suggests that cortical cells with direct motoneuronal connections increase their excitability in relation to human walking. The significance of the differences in the late facilitatory and inhibitory effects during the different tasks is unclear.

Petersen, Nicolas; Christensen, Lars O D; Nielsen, Jens

1998-01-01

329

Abnormalities of the blink reflex in burning mouth syndrome.  

PubMed

To our knowledge, this is the first report on pain-related abnormalities of the eye blink reflex (BR) in a clinical pain patient population. The objective of this study was to evaluate the possible neuropathic mechanisms underlying the burning mouth syndrome (BMS), by means of objective electrophysiological examination of the trigemino-facial system. We studied the BR with stimulation of the supraorbital nerve (SON) with particular emphasis on the occurrence of the pain-related ultralate R3 components, and the habituation response of the R2 components. The subjects consisted of eleven BMS patients and 10 healthy control subjects. All patients underwent thorough clinical oral and neurological examinations. The motor function of the trigeminal nerve was assessed with a jaw reflex recording, and a needle-EMG examination of the facial and masticatory muscles was performed in the patients with abnormalities in the BR recordings. The jaw reflexes, the latencies of the BR components, and the needle-EMG examinations were normal in all patients. As a group, the BMS patients had statistically significantly higher stimulus thresholds for the tactile R 1 components of the BR compared with the control subjects. With non-noxious stimulation, the BMS patients showed more frequently pain-related R3 components (11/22 SONs) compared with the controls (3/20 SONs). In addition, four BMS patients had abnormal habituation of the R2 components. In two of these patients, the findings were segmental (i.e., unilateral), coinciding with the side of the subjective BM symptoms. The abnormalities of the BR tests appeared to be related to longer disease duration. Our results suggest a possible pathologic involvement of the nervous system in chronic BMS. PMID:9469537

Jääskeläinen, S K; Forssell, H; Tenovuo, O

1997-12-01

330

Parasympathetic reflex vasodilation in the cerebral hemodynamics of rats.  

PubMed

We investigated the role of parasympathetic reflex vasodilation in the regulation of the cerebral hemodynamics, and whether GABAA receptors modulate the response. We examined the effects of activation of the parasympathetic fibers through trigeminal afferent inputs on blood flow in the internal carotid artery (ICABF) and the cerebral blood vessels (rCBF) in parietal cortex in urethane-anesthetized rats. Electrical stimulation of the central cut end of the lingual nerve (LN) elicited intensity- and frequency-dependent increases in ICABF that were independent of changes in external carotid artery blood flow. Increases in ICABF were elicited by LN stimulation regardless of the presence or absence of sympathetic innervation. The ICABF increases evoked by LN stimulation were almost abolished by the intravenous administration of hexamethonium (10 mg kg(-1)) and were reduced significantly by atropine administration (0.1 mg kg(-1)). Although the LN stimulation alone had no significant effect on rCBF, LN stimulation in combination with a blocker of the GABAA receptor pentylenetetrazole increased the rCBF markedly. This increase in rCBF was reduced significantly by the administration of hexamethonium and atropine. These observations indicate that the increases in both ICABF and rCBF are evoked by parasympathetic activation via the trigeminal-mediated reflex. The rCBF increase evoked by LN stimulation is thought to be limited by the GABAA receptors in the central nervous system. These results suggest that the parasympathetic reflex vasodilation and its modulation mediated by GABA receptors within synaptic transmission in the brainstem are involved in the regulation of the cerebral hemodynamics during trigeminal afferent inputs. PMID:24504265

Ishii, Hisayoshi; Sato, Toshiya; Izumi, Hiroshi

2014-04-01

331

Modeling upper eyelid kinematics during spontaneous and reflex blinks.  

PubMed

To test a mathematical model for measuring blinking kinematics. Spontaneous and reflex blinks of 23 healthy subjects were recorded with two different temporal resolutions. A magnetic search coil was used to record 77 blinks sampled at 200 Hz and 2 kHz in 13 subjects. A video system with low temporal resolution (30 Hz) was employed to register 60 blinks of 10 other subjects. The experimental data points were fitted with a model that assumes that the upper eyelid movement can be divided into two parts: an impulsive accelerated motion followed by a damped harmonic oscillation. All spontaneous and reflex blinks, including those recorded with low resolution, were well fitted by the model with a median coefficient of determination of 0.990. No significant difference was observed when the parameters of the blinks were estimated with the under-damped or critically damped solutions of the harmonic oscillator. On the other hand, the over-damped solution was not applicable to fit any movement. There was good agreement between the model and numerical estimation of the amplitude but not of maximum velocity. Spontaneous and reflex blinks can be mathematically described as consisting of two different phases. The down-phase is mainly an accelerated movement followed by a short time that represents the initial part of the damped harmonic oscillation. The latter is entirely responsible for the up-phase of the movement. Depending on the instantaneous characteristics of each movement, the under-damped or critically damped oscillation is better suited to describe the second phase of the blink. PMID:20547184

Malbouisson, Jorge Mario C; Messias, Andre; Garcia, Denny Marcos; Cechetti, Sheila de Paula; Barbosa, José Carlos; Cruz, Antonio Augusto Velasco

2010-08-15

332

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

333

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

334

Reflexive reasoning for distributed real-time systems  

NASA Technical Reports Server (NTRS)

This paper discusses the implementation and use of reflexive reasoning in real-time, distributed knowledge-based applications. Recently there has been a great deal of interest in agent-oriented systems. Implementing such systems implies a mechanism for sharing knowledge, goals and other state information among the agents. Our techniques facilitate an agent examining both state information about other agents and the parameters of the knowledge-based system shell implementing its reasoning algorithms. The shell implementing the reasoning is the Distributed Artificial Intelligence Toolkit, which is a derivative of CLIPS.

Goldstein, David

1994-01-01

335

The proprioceptive reflex control of the intercostal muscles during their voluntary activation  

PubMed Central

1. A quantitative study has been made of the reflex effects of sudden changes in mechanical load on contracting human intercostal muscles during willed breathing movements involving the chest wall. Averaging techniques were applied to recordings of electromyogram (EMG) and lung volume, and to other parameters of breathing. 2. Load changes were effected for brief periods (10-150 msec) at any predetermined lung volume by sudden connexion of the airway to a pressure source variable between ± 80 cm H2O so that respiratory movement could be either assisted or opposed. In some experiments airway resistance was suddenly reduced by porting from a high to a low resistance external airway. 3. Contracting inspiratory and expiratory intercostal muscles showed a `silent period' with unloading which is attributed to the sudden withdrawal from intercostal motoneurones of monosynaptic excitation of muscle spindle origin. 4. For both inspiratory and expiratory intercostal muscles the typical immediate effect of an increase in load was an inhibitory response (IR) with a latency of about 22 msec followed by an excitatory response (ER) with a latency of 50-60 msec. 5. It was established using brief duration stimuli (< 40 msec) that the IR depended on mechanical events associated with the onset of stimulation, whereas stimuli greater than 40 msec in duration were required to evoke the ER. 6. For constant expiratory flow rate and a constant load, the ER of expiratory intercostal muscles increased as lung volume decreased within the limits set by maximal activation of the motoneurone pool as residual volume was approached. 7. The ER to a constant load increased directly with the expiratory flow rate at which the load applied, also within limits set by maximal activation of the motoneurone pool. 8. For a given load, the ER during phonation was greater than that occurring at a similar expiratory flow rate without phonation when the resistance of the phonating larynx was mimicked by an external airway resistance. 9. It is argued that the IR is due to autogenetic inhibition arising from tendon organs and that the ER is due to autogenetic excitation arising from intercostal muscle spindles. 10. The initial dominance of inhibition in this dual proprioceptive reflex control was not predicted by the servo theory. It is proposed that the reflex pathways subserving autogenetic inhibition are under a centrifugal control which determines in relation to previous experience (learning) the conditions under which autogenetic facilitation is allowed.

Davis, J. Newsom; Sears, T. A.

1970-01-01

336

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.

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

2014-01-01

337

Reflex Influence of 'Somatic Pressor and Depressor Afferents' on Resistance and Capacitance Vessels and on Transcapillary Fluid Exchange.  

National Technical Information Service (NTIS)

The reflex circulatory effects of afferent somatic nerve stimulation were studied in the different consecutive vascular sections in skeletal muscle and intestine. In skeletal muscle the somatic pressor reflex elicited constriction of resistance and capaci...

B. Johansson O. Lundgren S. Mellander

1964-01-01

338

Differences of blink-reflex abnormalities in patients suffering from idiopathic and symptomatic trigeminal neuralgia  

Microsoft Academic Search

Summary We investigated the brainstem blink reflex in patients suffering from idiopathic and symptomatic trigeminal neuralgia to establish possible dysfunction in the reflex cycle and determine eventual differences between the two disease types. The study included 35 patients with idiopathic disease and seven patients with symptomatic disease, their results compared with those of 50 normal controls. We stimulated the forehead

Ivan Mikula; Zlatko Trkanjec; Ružica Negoveti?; Snježana Miškov; Vida Demarin

2005-01-01

339

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

ERIC Educational Resources Information Center

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

McPhillips, M.; Sheehy, N.

2004-01-01

340

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

ERIC Educational Resources Information Center

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

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

2012-01-01

341

Pharyngoglottal Closure Reflex: Characterization in Healthy Young, Elderly and Dysphagic Patients with Predeglutitive Aspiration  

Microsoft Academic Search

Background: Mechanism(s) of aspiration, a common complication of oropharyngeal dysphagia, is not completely elucidated. Since the pharyngoglottal closure reflex induces vocal cord adduction in healthy young humans, it may help prevent aspiration during premature spill of oral content. Objective: The objective of this study was to characterize this reflex in normal young and elderly humans and dysphagic patients with predeglutitive

Reza Shaker; Junlong Ren; Eytan Bardan; Caryn Easterling; Kulwinder Dua; Pengyan Xie; Mark Kern

2003-01-01

342

Temporal acuity in auditory function in the rat: Reflex inhibition by brief gaps in noise  

Microsoft Academic Search

Previous results show that the acoustic startle reflex in the rat is inhibited if a relatively weak stimulus precedes the startle-eliciting tone burst. The present 5 experiments explored the effect of brief silent periods (gaps) in white noise on the startle reflex in order to describe the limits of temporal resolution in the auditory system of 12 Long-Evans hooded rats.

James R. Ison

1982-01-01

343

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

344

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

PubMed Central

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

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

2011-01-01

345

Reflex responses of motor units in human masseter muscle to mechanical stimulation of a tooth  

Microsoft Academic Search

The reflex responses evoked by controlled mechanical stimulation of an upper central incisor tooth in single motor units in the human masseter muscle were examined. The stimuli were (brisk) taps and (slow) pushes of about 2 N peak force, applied orthogonally to the labial surface of the ipsilateral upper central incisor tooth. The reflex responses of the motor units were

Kemal S. Türker; Pål Brodin; Timothy S. Miles

1994-01-01

346

Selective activation of human soleus or gastrocnemius in reflex responses during walking and running  

Microsoft Academic Search

Phase-dependent reflex modulation was studied by recording the electromyographic (EMG) responses in soleus (SOL) and gastrocnemius medialis (GM) to a 20 ms train of 5 electrical pulses, applied to the sural or tibial nerve at the ankle, in 14 volunteers walking or running on a treadmill. Although both the spontaneous activity and the reflex responses were usually similar for both

J. Duysens; A. A. M. Tax; B. Doelen; M. Trippel; V. Dietz

1991-01-01

347

Unmasking of the trigemino-accessory reflex in accessory facial anastomosis  

Microsoft Academic Search

OBJECTIVETo evaluate the possible blink reflex responses in facial muscles reinnervated by the accessory nerve.METHODEleven patients with a complete facial palsy were submitted to a surgical repair by an accessory facial nerve anastomosis (AFA). In this pathological group, blink reflex was studied by means of percutaneous electrical stimulation of the supraorbital nerve and recording from the orbicularis oculi muscle. A

Angel Esteban; Julio Prieto

1999-01-01

348

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

PubMed Central

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

Tanino, Yoshitsugu; Suzuki, Toshiaki

2014-01-01

349

Effects of Motoneuron Properties on Reflex Stability in Spastic Subjects: A Simulation Study.  

National Technical Information Service (NTIS)

The influence of motoneuron pool properties on the stability of the stretch reflex at the ankle in subjects with spinal cord injury was tested using a comprehensive model of the reflex pathway. This model included the passive and active components of the ...

J. M. Hidler W. Z. Rymer

2001-01-01

350

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

ERIC Educational Resources Information Center

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

Smyth, Mary; Anderson, Mike; Hammond, Geoff

1999-01-01

351

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

ERIC Educational Resources Information Center

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

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

2009-01-01

352

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

Microsoft Academic Search

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

Sara Delamont

2009-01-01

353

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

354

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

355

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

Microsoft Academic Search

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

DAVID A. MORILAK; BARRY L. JACOBS

356

Plasticity of lumbosacral monosynaptic reflexes after a ventral root transection injury in the adult cat  

Microsoft Academic Search

Injuries to spinal ventral roots may induce plastic changes in adjacent segmental reflex pathways. Earlier studies in the cat have demonstrated that a partial loss of target motoneurons, following a ventral root avulsion injury, induces a compensatory enhancement of monosynaptic reflexes in adjacent segments. Here, we studied electrophysiologically the effects of a primarily non-lethal motoneuron injury of lumbosacral ventral roots

Leif A. Havton; Jan-Olof Kellerth

2004-01-01

357

New method for quantification and statistical analysis of nociceptive reflex receptive fields in humans  

Microsoft Academic Search

A method for quantifying nociceptive withdrawal reflex receptive fields in human volunteers and patients is described. The reflex receptive field (RRF) for a specific muscle denotes the cutaneous area from which a muscle contraction can be evoked by a nociceptive stimulus. The method is based on random stimulations presented in a blinded sequence to 10 stimulation sites. The sensitivity map

Alban Y. Neziri; Michele Curatolo; Alessandra Bergadano; Steen Petersen-Felix; Anthony Dickenson; Lars Arendt-Nielsen; Ole K. Andersen

2009-01-01

358

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

359

Hypothalamic stimulation and baroceptor reflex interaction on renal nerve activity.  

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

360

Criteria for reflex peripheral smear review in infants.  

PubMed

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

Froom, Paul; Isakov, Elada; Barak, Mira

2014-06-01

361

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

PubMed

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

Walklate, Sandra; Mythen, Gabriel

2010-03-01

362

Intraurethral stimulation evokes bladder responses via two distinct reflex pathways  

PubMed Central

Purpose Recent animal studies have shown that selective activation of pudendal nerve branches can evoke bladder responses through two distinct reflex pathways. In this study, we examined intraurethral electrical stimulation (IES) as a minimally invasive means to activate selectively these pathways in the cat. Materials and Methods The bladder responses evoked by IES were measured in ?-chloralose anesthetized male cats at different stimulation frequencies, stimulation intensities, and intraurethral locations. Results IES evoked both inhibitory and excitatory bladder reflexes dependent on stimulation frequency and location. IES in the penile urethra (0–3 cm from the urethral meatus) at 33 Hz stimulation evoked bladder contraction and at 10 Hz stimulation evoked bladder relaxation, and these responses were abolished following bilateral transection of the dorsal penile nerves. Stimulation in the membranous urethra (5–7 cm from the urethral meatus) at 2, 10, and 33 Hz stimulation evoked bladder contractions, and these responses were abolished following bilateral transection of the cranial sensory nerves. Following acute spinal cord transection, bladder contractions were still evoked by 33 Hz stimulation in the penile urethra but not by stimulation at any frequency in the membranous urethra. Conclusions IES selectively evoked bladder responses by activation of two distinct pudendal afferent pathways, and the responses were dependent on the stimulation frequency and location. IES is a valid means to determine the pathways involved in bladder responses evoked by pudendal nerve stimulation.

Woock, John P; Yoo, Paul B; Grill, Warren M

2011-01-01

363

The vestibulo-collic reflex is abnormal in migraine.  

PubMed

Interictal evoked central nervous system responses are characterized in migraineurs by a deficit of habituation, at both cortical and subcortical levels. The click-evoked vestibulo-collic reflex (VCR) allows the assessment of otolith function and an oligosynaptic pathway linking receptors in the saccular macula to motoneurons of neck muscles. Three blocks of 75 averaged responses to monaural 95-dB normal hearing level 3-Hz clicks were recorded over the contracted ipsilateral sternocleidomastoid muscle in 25 migraineurs between attacks and 20 healthy subjects, without vestibular symptoms. Amplitudes, raw and corrected for baseline electromyography, were significantly smaller in migraine patients. Whereas in healthy volunteers the VCR habituated during stimulus repetition (-4.96% +/- 14.3), potentiation was found in migraineurs (4.34% +/- 15.3; P = 0.04). The combination with a reduced mean amplitude does not favour vestibular hyperexcitability as an explanation for the habituation deficit in migraine, but rather an abnormal processing of repeated stimuli in the reflex circuit. PMID:17784856

Allena, M; Magis, D; De Pasqua, V; Schoenen, J; Bisdorff, A R

2007-10-01

364

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

365

Effects of galvanic vestibular stimulation on postural limb reflexes and neurons of spinal postural network.  

PubMed

Quadrupeds maintain the dorsal side up body orientation due to the activity of the postural control system driven by limb mechanoreceptors. Binaural galvanic vestibular stimulation (GVS) causes a lateral body sway toward the anode. Previously, we have shown that this new position is actively stabilized, suggesting that GVS changes a set point in the reflex mechanisms controlling body posture. The aim of the present study was to reveal the underlying neuronal mechanisms. Experiments were performed on decerebrate rabbits. The vertebral column was rigidly fixed, whereas hindlimbs were positioned on a platform. Periodic lateral tilts of the platform caused postural limb reflexes (PLRs): activation of extensors in the loaded and flexing limb and a decrease in extensor activity in the opposite (unloaded and extending) limb. Putative spinal interneurons were recorded in segments L4-L5 during PLRs, with and without GVS. We have found that GVS enhanced PLRs on the cathode side and reduced them on the anode side. This asymmetry in PLRs can account for changes in the stabilized body orientation observed in normal rabbits subjected to continuous GVS. Responses to platform tilts (frequency modulation) were observed in 106 spinal neurons, suggesting that they can contribute to PLR generation. Two neuron groups were active in opposite phases of the tilt cycle of the ipsi-limb: F-neurons in the flexion phase, and E-neurons in the extension phase. Neurons were driven mainly by afferent input from the ipsi-limb. If one supposes that F- and E-neurons contribute, respectively, to excitation and inhibition of extensor motoneurons, one can expect that the pattern of response to GVS in F-neurons will be similar to that in extensor muscles, whereas E-neurons will have an opposite pattern. We have found that ~40% of all modulated neurons meet this condition, suggesting that they contribute to the generation of PLRs and to the GVS-caused changes in PLRs. PMID:22514291

Hsu, L-J; Zelenin, P V; Orlovsky, G N; Deliagina, T G

2012-07-01

366

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

PubMed Central

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

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

2014-01-01

367

Recovery of cardiopulmonary reflexes in monkeys undergoing heart-lung transplantation.  

PubMed

After heart-lung transplantation in primates, cardiopulmonary reflexes were tested and shown to be present. The Hering-Breuer and cough reflexes were tested, as well as responses to an inhaled respiratory stimulant, vasodilator, and an intravenous anticholinesterase and antimuscarinic agent. Recovery of these responses, except to the anticholinesterase agent, suggests that reinervation occurs in autotransplanted organs in primates. The Hering-Breuer reflex was present at 1.9 and 2.2 months after the operation in two animals subjected to autotransplantation. These cardiopulmonary reflex responses were also demonstrated in two allograft recipients studied at 15 and 16.9 months after the operation. Return of protective reflexes such as coughing may be an important mechanism to prevent aspiration pneumonitis and other complications in humans. PMID:2796358

Mihm, F G; Popovic, B K; Noe, C; Hilberman, M; Reitz, B A

1989-10-01

368

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

PubMed Central

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

2012-01-01

369

[Reflex responses of human perioral muscles to mechanical stimulation of the vestibular oris mucosa].  

PubMed

To investigate the effects on perioral muscles with mechanical stimulation to the mucosa electromyograms were recorded in nine subjects. Results were as follows: 1. Tonic excitatory reflex of m. orbicularis oris and m. mentalis was evoked by the non-painful pressure stimulation to lower lip mucosa. These responses were increased, as the stimulus strength was increased. 2. Reflex responses to stimulation of the corner of the mouth and lower lip mucosa were greater than that of buccal mucosa. The response in m. orbicularis oris superior (O.O.S.) to stimulation of upper lip mucosa was greater than in m. orbicularis oris inferior (O.O.I.). And the response in O.O.I. to stimulation of lower lip mucosa was greater than the response in O.O.S. 3. Tonic excitatory reflex was abolished after local anesthesia of the stimulation area. 4. Excitatory reflex was reversed to inhibitory reflex, when background activity of three muscles was changed by voluntary lip closure. When background activity was weak, excitatory reflex was induced by pressure stimulation. On the contrary, when background activity was strong, inhibitory reflex was induced by the same stimulation. When background activity was moderate, excitatory reflex in O.O.I. and inhibitory one in O.O.S. was easily induced by lower lip stimulation. On the other hand, by upper stimulation, excitatory reflex in O.O.S. and inhibitory one in O.O.I. was easily induced. These results suggest that the orthodontic appliance placed on the vestibular oris gives mechanical stimulation to oral mucosa, which induce reflex contraction in perioral muscles. PMID:2133876

Saito, T

1990-04-01

370

Gradual enlargement of human withdrawal reflex receptive fields following repetitive painful stimulation.  

PubMed

Dynamic changes in the topography of the human withdrawal reflex receptive fields (RRF) were assessed by repetitive painful stimuli in 15 healthy subjects. A train of five electrical stimuli was delivered at a frequency of 3 Hz (total train duration 1.33 s). The train was delivered in random order to 10 electrode sites on the sole of the foot. Reflexes were recorded from tibialis anterior, soleus, vastus lateralis, biceps femoris, and iliopsoas (IL). The RRF changes during the stimulus train were assessed during standing with even support on both legs and while seated. The degree of temporal summation was depending on stimulation site. At the most sensitive part of the RRF, a statistically significant increase in reflex size was seen after two stimuli while four stimuli were needed to observe reflex facilitation at less sensitive electrode sites. Hence, the region from which reflexes could be evoked using the same stimulus intensity became larger through the train, that is, the RRF was gradually expanding. Reflexes evoked by stimuli four and five were of the same size. No reflex facilitation was seen at other stimulus sites outside the RRF. In all muscles except in IL, the largest reflexes were evoked when the subjects were standing. In the ankle joint, the main withdrawal pattern consisted of plantar flexion and inversion when the subjects were standing while dorsi-flexion was prevalent in the sitting position. Up to 35 degrees of knee and hip flexion were evoked often leading to a lift of the foot from the floor during standing. In conclusion, a gradual expansion of the RRF was seen in all muscles during the stimulus train. Furthermore, the motor programme task controls the reflex sensitivity within the reflex receptive field and, hence, the sensitivity of the temporal summation mechanism. PMID:15854591

Andersen, Ole K; Spaich, Erika G; Madeleine, Pascal; Arendt-Nielsen, Lars

2005-05-01

371

Reflex modification in the domain of startle: II. The anomalous history of a robust and ubiquitous phenomenon  

Microsoft Academic Search

Describes the discovery and rediscoveries of the phenomenon of the reflex modification of the startle reaction. The startle reaction is elicited in animals by abrupt stimuli in diverse modalities. Weak stimuli can modify the reflex. This phenomenon of reflex modification has been discovered on at least 4 separate occasions since the mid-19th century, beginning with I. M. Sechenov in 1862.

James R. Ison; Howard S. Hoffman

1983-01-01

372

EMG, force and discharge rate analysis of human jaw reflexes in response to axial stimulation of the incisor  

Microsoft Academic Search

Reflex studies utilising controlled stimulation along the long axis of human incisors are relatively new, and the effects that various stimulus parameters have on the elicited reflexes are not fully understood. Twelve subjects were recruited to determine the effects that contraction level, stimulus force and amount of constant force applied between stimuli have on the reflex response of the masseter

Russell S. A. Brinkworth; Kemal S. Türker

2005-01-01

373

The Effects Of Input And Interaction On The Acquisition Of French Reflexive Verbs Within The Second Language University Classroom  

Microsoft Academic Search

This study investigates the effects of input and interaction activities on the acquisition of French reflexive verbs. In this research project, I address the following two research questions: 1) Will acquisition and production of French reflexive verbs vary according to instructional treatment? 2) Will acquisition and production of French reflexive verbs vary according to the proficiency level of the participants?

Virginia Hudson Osborn

2006-01-01

374

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

375

Olfactory classical conditioning in newborn mice  

Microsoft Academic Search

Determining the behavioural phenotype of genetically altered mice is a valuable approach for elucidating the function of genes and their role in cognitive disorders. Methods for phenotyping newborn mice are scarce and generally confined to sensorimotor reflexes. Here, we describe a simple method for assessing associative abilities in newborn mice. We used a two-odour-choice classical conditioning paradigm in mice from

Myriam Bouslama; Estelle Durand; Laetitia Chauvière; Omer Van den Bergh; Jorge Gallego

2005-01-01

376

Organisation of sensitisation of hind limb withdrawal reflexes from acute noxious stimuli in the rabbit  

PubMed Central

Spatial aspects of central sensitisation were investigated by studying the effects on three hind limb withdrawal reflexes of an acute noxious stimulus (20 % mustard oil) applied to a number of locations around the body in decerebrate and in anaesthetised rabbits. Reflex responses to electrical stimulation of the toes were recorded from the ankle flexor tibialis anterior (TA) and the knee flexor semitendinosus (ST), whereas responses to stimulation of the heel were recorded from the ankle extensor medial gastrocnemius (MG). In non-spinalised, decerebrated, pentobarbitone-sedated preparations, flexor reflexes were facilitated significantly from sites on the plantar surface of the ipsilateral foot but were either inhibited or unaffected by stimulation of sites away from this location. The heel–MG reflex was facilitated from the ipsilateral heel and was inhibited from a number of ipsilateral, contralateral and off-limb sites. In decerebrated, spinalised, pentobarbitone-sedated animals, mustard oil applied to any site on the ipsilateral hind limb enhanced both flexor reflexes, whereas the MG reflex was enhanced only after stimulation at the ipsilateral heel and was inhibited after stimulation of the toe tips or TA muscle. Mustard oil on the contralateral limb had no effect on any reflex. In rabbits anaesthetised with pentobarbitone and prepared with minimal surgical interference, the sensitisation fields for the heel–MG and toes–TA reflexes were very similar to those in non-spinal decerebrates whereas that for toes–ST was more like the pattern observed in spinalised animals. In no preparation was sensitisation or inhibition of reflexes related to the degree of motoneurone activity generated in direct response to the sensitising stimulus. This study provides for the first time a complete description of the sensitisation fields for reflexes to individual muscles. Descending controls had a marked effect on the area from which sensitisation of flexor reflexes could be obtained, as the sensitisation fields for the flexor reflexes evoked from the toes were larger in spinalised compared to decerebrated, non-spinalised animals. The intermediate sizes of sensitisation fields in anaesthetised animals suggests that the area of these fields can be dynamically controlled from the brain. On the other hand, the sensitisation field for the heel–MG reflex varied little between preparations and appears to be a function of spinal neurones.

Harris, John; Clarke, Rob W

2003-01-01

377

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.

2013-01-01

378

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

379

Enhanced magnetic ionization in hydrogen reflex discharge plasma source  

SciTech Connect

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

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

2005-03-01

380

Enhanced magnetic ionization in hydrogen reflex discharge plasma source  

NASA Astrophysics Data System (ADS)

The effect of enhanced magnetic ionization on the external and internal parameters of a high-density, low pressure reflex plasma source operating in hydrogen is studied. The Langmuir probe method and Druyvesteyn procedure coupled with suitable software are used to measure the internal parameters. The bulk plasma region is free of an electric field and presents a high degree of uniformity. The electron energy distribution function is bi-Maxwellian with a dip/shoulder structure around 5.5 eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density ne is as high as 1018 m-3, and the electron temperature Te is as low as a few tens of an electron volt, for dissipated energy of tens of Watts. The bulk plasma density scales with the dissipated power.

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

2005-03-01

381

Developmental tuning of reflexive attentional effect to biological motion cues  

PubMed Central

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

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

2014-01-01

382

Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

383

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

384

Developmental tuning of reflexive attentional effect to biological motion cues.  

PubMed

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

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

2014-01-01

385

Olfactory bulbectomy attenuates cardiovascular sympathoexcitatory reflexes in rats.  

PubMed

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

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

2002-12-01

386

Organization of the neural switching circuitry underlying reflex micturition  

PubMed Central

The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain and spinal cord that coordinates the activity of the bladder and urethral outlet. Experimental studies in animals indicate that urine storage is modulated by reflex mechanisms in the spinal cord, whereas voiding is mediated by a spinobulbospinal pathway passing through a coordination centre in the rostral brain stem. Many of the neural circuits controlling micturition exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. This study summarizes the anatomy and physiology of the spinal and supraspinal micturition switching circuitry and describes a computer model of these circuits that mimics the switching functions of the bladder and urethra at the onset of micturition.

de Groat, W. C.; Wickens, C.

2013-01-01

387

Projection neurons of the vestibulo-sympathetic reflex pathway.  

PubMed

Changes in head position and posture are detected by the vestibular system and are normally followed by rapid modifications in blood pressure. These compensatory adjustments, which allow humans to stand up without fainting, are mediated by integration of vestibular system pathways with blood pressure control centers in the ventrolateral medulla. Orthostatic hypotension can reflect altered activity of this neural circuitry. Vestibular sensory input to the vestibulo-sympathetic pathway terminates on cells in the vestibular nuclear complex, which in turn project to brainstem sites involved in the regulation of cardiovascular activity, including the rostral and caudal ventrolateral medullary regions (RVLM and CVLM, respectively). In the present study, sinusoidal galvanic vestibular stimulation was used to activate this pathway, and activated neurons were identified through detection of c-Fos protein. The retrograde tracer Fluoro-Gold was injected into the RVLM or CVLM of these animals, and immunofluorescence studies of vestibular neurons were conducted to visualize c-Fos protein and Fluoro-Gold concomitantly. We observed activated projection neurons of the vestibulo-sympathetic reflex pathway in the caudal half of the spinal, medial, and parvocellular medial vestibular nuclei. Approximately two-thirds of the cells were ipsilateral to Fluoro-Gold injection sites in both the RVLM and CVLM, and the remainder were contralateral. As a group, cells projecting to the RVLM were located slightly rostral to those with terminals in the CVLM. Individual activated projection neurons were multipolar, globular, or fusiform in shape. This study provides the first direct demonstration of the central vestibular neurons that mediate the vestibulo-sympathetic reflex. J. Comp. Neurol. 522:2053-2074, 2014. © 2013 Wiley Periodicals, Inc. PMID:24323841

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

2014-06-15

388

Normal cardiovascular reflex testing in patients with parkin disease.  

PubMed

The objective of this study was to investigate cardiovascular autonomic function in patients with parkin disease. Ten patients with a genetically confirmed diagnosis were compared to 11 healthy controls. Symptoms related to autonomic dysfunction were collected by structured interviews. Cardiovascular autonomic reflex function was evaluated using a standard battery of eight tests. Autonomic tests included the study of sympathetic function through the analysis of blood pressure responses to head-up tilt, standing, isometric hand grip, cold pressor, mental arithmetic, Valsalva maneuver (Valsalva overshoot), and the study of parasympathetic function through the analysis of heart rate responses to deep breathing, hyperventilation, and Valsalva ratio. Seven out of 10 patients reported symptoms involving different aspects of autonomic function, while 5 out of 11 controls reported symptoms related exclusively to orthostatic dizziness and constipation. Symptoms related to bladder dysfunction were the most frequent autonomic abnormality occurring in six patients, followed by orthostatic dizziness and dry mouth (in four patients each). Constipation occurred in three patients, sialorrhea in two, and erectile dysfunction, dry eye, and warm intolerance in one each. Cardiovascular reflex testing revealed no difference between patients and controls in quantitative assessment of both sympathetic and parasympathetic functions, except for diastolic blood pressure after isometric hand grip that did not increase normally in parkin patients compared to controls (P = 0.007). These data show that cardiovascular dysautonomia is not associated to the parkin phenotype, whereas urinary complaints are more frequently reported by parkin patients than by controls. Urinary dysautonomia warrants further investigation in patients with parkin disease. PMID:17230469

Del Sorbo, Francesca; Elia, Antonio E; De Joanna, Gabriella; Romito, Luigi M; Garavaglia, Barbara; Albanese, Alberto

2007-03-15

389

Cholesteric Liquid Crystal Based Reflex Color Reflective Displays  

NASA Astrophysics Data System (ADS)

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

Khan, Asad

2012-02-01

390

Neuromodulation in a rat model of the bladder micturition reflex  

PubMed Central

A rat model of bladder reflex contraction (BRC) was used to determine the optimal frequency and intensity of spinal nerve (SN) stimulation to produce neuromodulation of bladder activity and to assess the therapeutic mechanisms of this neuromodulation. In anesthetized female rats (urethane 1.2 g/kg ip), a wire electrode was used to produce bilateral stimulation of the L6 SN. A cannula was placed into the bladder via the urethra, and the urethra was ligated to ensure an isovolumetric bladder. Saline infusion induced BRC. Electrical stimulation of the SN produced a frequency- and intensity-dependent attenuation of the frequency of bladder contractions. Ten-herz stimulation produced maximal inhibition; lower and higher stimulation frequency produced less attenuation of BRC. Attenuation of bladder contraction frequency was directly proportional to the current intensity. At 10 Hz, stimulation using motor threshold pulses (Tmot) produced a delayed inhibition of the frequency of bladder contractions to 34 ± 11% of control. Maximal bladder inhibition appeared at 10 min poststimulation. High current intensity at 0.6 mA (?6 * Tmot) abolished bladder contraction during stimulation, and the inhibition was sustained for 10 min poststimulation (prolonged inhibition). Furthermore, in rats pretreated with capsaicin (125 mg/kg sc), stimulation produced a stronger inhibition of BRC. The inhibitory effects on bladder contraction may be mediated by both afferent and efferent mechanisms. Lower intensities of stimulation may activate large, fast-conducting fibers and actions through the afferent limb of the micturition reflex arc in SN neuromodulation. Higher intensities may additionally act through the efferent limb.

Nickles, Angela; Nelson, Dwight E.

2012-01-01

391

[Modulation of soleus H-reflex by teeth clenching].  

PubMed

Modulation of the human soleus H-reflex (Sol. H-R) was studied during voluntary teeth clenching in 11 healthy adult volunteers, to investigate the possible correlation of motor functions between the jaw and body. The following results were obtained: (1) Sol. H-R was facilitated during the maximum voluntary teeth clenching more than during the maximum voluntary efforts in the other parts of the body, i.e., Jendrassik maneuver and clenching of both hands. (2) The amount of the Sol. H-R facilitation increased with the masseter EMG activity. (3) Facilitation of the Sol. H-R in association with teeth clenching started ca 60ms before the onset of the masseter EMG activity, reached its peak ca. 100ms after the onset and thereafter decreased to a certain plateau level in accordance with the masseter EMG activity level. (4) During the inhibition of the masseter EMG reflexively evoked by electrical stimulation of the lower lip, the amount of the facilitation of the Sol. H-R during teeth clenching decreased compared with that without lip stimulation, though the facilitation was still retained. It was concluded that: 1) The excitability of the Sol. H-R is remarkably elevated during teeth clenching. 2) There is a positive correlation between the amount of the facilitation of the Sol. H-R and the teeth clenching force level. 3) The facilitation is due to both the descending influence from the higher brain and the afferent inputs from the oral structures. It is assumed that the oral motor activity exerts a strong influence on the bodily motor function in general. PMID:1795137

Miyahara, T

1991-12-01

392

Trigeminocardiac reflex in neurosurgical practice: Report of two new cases  

PubMed Central

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

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

2013-01-01

393

Manometric evidence for a phonation-induced UES contractile reflex.  

PubMed

The mechanism against entry of gastric content into the pharynx during high-intensity vocalization such as seen among professional singers is not known. We hypothesized that phonation-induced upper esophageal sphincter (UES) contraction enhances the pressure barrier against entry of gastroesophageal contents into pharynx. To determine and compare the effect of phonation on luminal pressures of the esophagus and its sphincters, we studied 17 healthy volunteers (7 male, 10 female) by concurrent high-resolution manometry and voice analysis. We tested high- and low-pitch vowel sounds. Findings were verified in six subjects by UES manometry using a water-perfused sleeve device. Eight of the volunteers (2 male, 6 female) had concurrent video fluoroscopy with high-resolution manometry and voice recording. Fluoroscopic images were analyzed for laryngeal movement. To define the sex-based effect, subgroup analysis was performed. All tested phonation frequencies and intensities induced a significant increase in UES pressure (UESP) compared with prephonation pressure. The magnitude of the UESP increase was significantly higher than that of the distal esophagus, the lower esophageal sphincter (LES), and the stomach. Concurrent videofluoroscopy did not show posterior laryngeal movement during phonation, eliminating a purely mechanical cause for phonation-induced UESP increase. Subgroup analysis demonstrated phonation-induced UESP increases in males that were significantly greater than those of females. Phonation induces a significant increase in UESP, suggesting the existence of a phonation-induced UES contractile reflex. UESP increase due to this reflex is significantly higher than that of the distal esophagus, LES, and stomach. The phonation-induced UESP increase is influenced by sex. PMID:18239061

Perera, Lilani; Kern, Mark; Hofmann, Candy; Tatro, Linda; Chai, Krisna; Kuribayashi, Shiko; Lawal, Adeyemi; Shaker, Reza

2008-04-01

394

Visceral and postural reflexes evoked by genital stimulation in urethane-anesthetized female rats.  

PubMed

The present study describes several muscular reflexes produced by genital stimulation, the nerves that subserve them, and the visceral and postural effects induced by these reflexes. Electrical stimulation of the iliococcygeus (ic) and pubococcygeus (pc) (striated) muscles produced movement of the vaginal orifice and wall, membranous urethra, tail and pelvis. Electrical stimulation of the psoas major (pm) or iliacus (i) (striated) muscles produced movements of the lumbar vertebrae and extension of the ipsilateral hindlimb. Sensory mechanostimulation elicited responses of these muscles as follows: stimulation of the perineal skin, clitoral sheath or distal vagina produced reflex contraction of the ic and pc muscles. Stimulation of the cervix produced reflex contraction of the pm and i muscles and also blocked the above reflex contraction of the ic and pc muscles. Both the cervical stimulation-induced blockage of the ic and pc reflex response, and the cervical stimulation-induced activation of pm and i muscles was prevented by bilateral transection of the viscerocutaneous branch of the pelvic nerve. Based on the above observations, it is proposed that stimulation of the vaginal surface of the cervix resulting from penile intromission and/or seminal plug deposition during mating behavior in the rat may reflexively active pm and i, thereby contributing to the hindleg postural rigidity and lordotic dorsiflexion that are characteristic of the normal mating posture in female rats. PMID:1533338

Martinez-Gomez, M; Chirino, R; Beyer, C; Komisaruk, B R; Pacheco, P

1992-03-20

395

Long latency reflex force of human finger muscles in response to imposed sinusoidal movements.  

PubMed

Reflex stiffness of the flexing human index finger was studied using sinusoidal movements at 3-16 Hz. The Nyquist stiffness diagram indicates the presence of a 'presonance' at around 4 Hz, its 'C' shape after correction for the mechanical properties of the relaxed finger is consistent with the involvement of a stretch reflex in its generation. This contention was supported by the presence of negative friction around 4 Hz and the disappearance of the modulation of the stiffness curve after afferent ischaemic block. Correction for the mechanical properties of active muscle, measured after afferent block, permitted the isolation of the reflex component of stiffness. The circular form of the Nyquist diagram indicates a relatively flat frequency response for the reflex over the range tested, and its radius gives a measure of reflex gain. The low value of the frequency at which the frictional force is minimal, suggests the involvement of a reflex of longer than spinal latency. This is discussed in relation to mechanisms of tremor genesis and the interaction of spinal and long latency reflexes in distal hand muscles. PMID:6745369

Noth, J; Matthews, H R; Friedemann, H H

1984-01-01

396

Effects of tonic vibration reflex on motor unit recruitment in human wrist extensor muscles.  

PubMed

Tonic vibration reflex was used to investigate the effects of muscle spindle Ia afferent activation on motor unit (MU) recruitment in human wrist extensor muscles. The MU force recruitment threshold recorded in the extensor carpi radialis muscles were quantitatively compared under two experimental situations: (1) during tonic isometric reflex contractions induced by mechanical tendon vibration and during voluntary contractions performed at the same velocity; (2) during two voluntary imposed ramp contractions (0.25 N.s-1) performed the one immediately before, and the other immediately after a tonic vibration reflex. In the first situation, it was observed that the Ia afferents activated by tendon vibration exerted a strong homonymous facilitatory action on their bearing muscles (extensor carpi radialis longus and brevis), while their heteronymous action on the synergistic muscle (extensor carpi ulnaris) was very weak. The MU recruitment thresholds in the extensor carpi radialis muscles were therefore significantly lower during the tonic reflex contraction than during the voluntary contraction. In the second situation, the tonic vibration reflex induced a facilitatory after-effect which decreased the MU recruitment thresholds during the subsequent voluntary imposed ramp contraction. It is suggested that this post-vibratory effect may have been due either to a postsynaptic potentiation of the motoneurones or to a reflex sensitization of the muscle spindles increasing their response to voluntary isometric contraction and consequently, increasing their facilitatory reflex action on the motoneurone pool. PMID:8448656

Romaiguère, P; Vedel, J P; Pagni, S

1993-01-29

397

Esophageal sensation in premature human neonates: temporal relationships and implications of aerodigestive reflexes and electrocortical arousals  

PubMed Central

Electrocortical arousal (ECA) as an effect of visceral provocation or of its temporal relationships with aerodigestive reflexes in premature neonates is not known. We tested the hypothesis that esophageal provocation results in both esophageal reflex responses and ECAs during sleep and that ECAs are dependent on the frequency characteristics of esophageal neuromotor responses. We defined the spatiotemporal relationship of ECAs in relation to 1) spontaneous pharyngoesophageal swallow sequences and gastroesophageal reflux (GER) events and 2) sensory-motor characteristics of esophageal reflexes. Sixteen healthy premature neonates born at 27.9 ± 3.4 wk were tested at 36.8 ± 1.9 wk postmenstrual age. Ninety-five midesophageal and 31 sham stimuli were given in sleep during concurrent manometry and videopolysomnography. With stimulus onset as reference point, we scored the response latency, frequency occurrence and duration of arousals, peristaltic reflex, and upper esophageal sphincter contractile reflex (UESCR). Changes in polysomnography-respiratory patterns and esophageal sensory-motor parameters were scored by blinded observers. Significantly (for each characteristic listed, P < 0.05), swallow sequences were associated with arousals and sleep state changes, and arousals were associated with incomplete peristalsis, response delays to lower esophageal sphincter relaxation, and prolonged esophageal clearance. GER events (73.5%) provoked arousals, and arousals were associated with response delays to peristaltic reflexes or clearance, sleep state modification, and prolonged respiratory arousal. Midesophageal stimuli (54%) provoked arousals and were associated with increased frequency, prolonged latency, prolonged response duration of peristaltic reflexes and UESCR, and increased frequency of sleep state changes and respiratory arousals. In human neonates, ECAs are provoked upon esophageal stimulation; the sensory-motor characteristics of esophageal reflexes are distinct when accompanied by arousals. Aerodigestive homeostasis is defended by multiple tiers of aerodigestive safety mechanisms, and when esophageal reflexes are delayed, cortical hypervigilance (ECAs) occurs.

Parks, Vanessa N.; Peng, Juan; Dzodzomenyo, Samuel; Fernandez, Soledad; Shaker, Reza; Splaingard, Mark

2012-01-01

398

Esophageal sensation in premature human neonates: temporal relationships and implications of aerodigestive reflexes and electrocortical arousals.  

PubMed

Electrocortical arousal (ECA) as an effect of visceral provocation or of its temporal relationships with aerodigestive reflexes in premature neonates is not known. We tested the hypothesis that esophageal provocation results in both esophageal reflex responses and ECAs during sleep and that ECAs are dependent on the frequency characteristics of esophageal neuromotor responses. We defined the spatiotemporal relationship of ECAs in relation to 1) spontaneous pharyngoesophageal swallow sequences and gastroesophageal reflux (GER) events and 2) sensory-motor characteristics of esophageal reflexes. Sixteen healthy premature neonates born at 27.9 ± 3.4 wk were tested at 36.8 ± 1.9 wk postmenstrual age. Ninety-five midesophageal and 31 sham stimuli were given in sleep during concurrent manometry and videopolysomnography. With stimulus onset as reference point, we scored the response latency, frequency occurrence and duration of arousals, peristaltic reflex, and upper esophageal sphincter contractile reflex (UESCR). Changes in polysomnography-respiratory patterns and esophageal sensory-motor parameters were scored by blinded observers. Significantly (for each characteristic listed, P < 0.05), swallow sequences were associated with arousals and sleep state changes, and arousals were associated with incomplete peristalsis, response delays to lower esophageal sphincter relaxation, and prolonged esophageal clearance. GER events (73.5%) provoked arousals, and arousals were associated with response delays to peristaltic reflexes or clearance, sleep state modification, and prolonged respiratory arousal. Midesophageal stimuli (54%) provoked arousals and were associated with increased frequency, prolonged latency, prolonged response duration of peristaltic reflexes and UESCR, and increased frequency of sleep state changes and respiratory arousals. In human neonates, ECAs are provoked upon esophageal stimulation; the sensory-motor characteristics of esophageal reflexes are distinct when accompanied by arousals. Aerodigestive homeostasis is defended by multiple tiers of aerodigestive safety mechanisms, and when esophageal reflexes are delayed, cortical hypervigilance (ECAs) occurs. PMID:21852361

Jadcherla, Sudarshan R; Parks, Vanessa N; Peng, Juan; Dzodzomenyo, Samuel; Fernandez, Soledad; Shaker, Reza; Splaingard, Mark

2012-01-01

399

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

PubMed Central

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

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

2013-01-01

400

Normalization reduces the spatial dependency of the jaw-stretch reflex activity in the human masseter muscle.  

PubMed

The jaw-stretch reflex is the short-latency response in the jaw-closing muscles after a sudden stretch. The hypothesis whether normalization of the jaw-stretch reflex amplitude with respect to prestimulus electromyographic (EMG) activity will make the amplitude more independent of the location of the electrodes over the masseter muscle was tested. A 5 x 6 electrode grid was used to record the jaw-stretch reflex from 25 sites over the right masseter muscle of 15 healthy men. The results showed that there was a significant site dependency of the prestimulus EMG activity and the reflex amplitude. High cross-correlation coefficients were found between the spatial distribution of mean prestimulus EMG activities and reflex amplitude. When the reflex amplitude was normalized with respect to the prestimulus EMG activity, no site dependency was found. In conclusion, normalization of the jaw-stretch reflex amplitude by the prestimulus EMG activity strongly reduces its spatial dependency. PMID:19768764

Koutris, Michail; Naeije, Machiel; Lobbezoo, Frank; Wang, Kelun; Arendt-Nielsen, Lars; Svensson, Peter; Farina, Dario

2010-01-01

401

Role of the cerebellum and the vestibular apparatus in regulation of orthostatic reflexes in the cat  

NASA Technical Reports Server (NTRS)

The contribution of the fastigial nucleus and the vestibular nerves (eighth cranial nerves) to the orthostatic reflexes in anesthetized, paralyzed cats was studied. Bilateral lesions of the rostral fastigial nucleus resulted in impairment of the reflex changes in blood pressure, femoral arterial flow, and resistance evoked by head-up tilting to 30 deg or 60 deg. The rostral fastigial nucleus, which might be triggered by the vestibular apparatus, appears to participate in concert with the baroreceptors in the initiation and possibly the maintenance of the orthostatic reflexes.

Doba, N.; Reis, D. J.

1974-01-01

402

Temperature dependence of soleus H-reflex and M wave in young and older women  

Microsoft Academic Search

The purpose of this study was to investigate the effect of altered local temperature on soleus H-reflex and compound muscle action potential (M wave) in young and older women. H-reflex and M wave responses were elicited in 10 young (22.3±3.3 years) and 10 older (72.5±3.2 years) women at three muscle temperatures: control (34.2±0.3°C), cold (31.3±0.5°C) and warm (37.1±0.2°C). H-reflex output, expressed as

Susan Dewhurst; Philip E. Riches; Myra A. Nimmo; Giuseppe De Vito

2005-01-01

403

Stretch reflex and servo action in a variety of human muscles.  

PubMed Central

1. In the long flexor of the thumb the latency of the stretch reflex and of other manifestations of servo action is some 45 msec, roughly double the latency of a finger jerk. 2. Tendon jerks are feeble or absent in the long flexor of the thumb even in subjects with brisk long-latency stretch reflexes in this muscle. This, and other facts, suggests that the nervous mechanism of the tendon jerk is different from that of the stretch reflex. 3. A muscle that has feeble tendon jerks may show a late component in the response to a tendon tap, with a latency similar to that of the long-latency stretch reflex. 4. On the hypothesis that the excess latency of the stretch reflex over that of a tendon jerk is because the stretch reflex employs a cortical rather than a spinal arc, the excess would be expected to be larger in magnitude for the long flexor of the big toe and smaller for the jaw closing muscles. This is confirmed, 5. An alternative hypothesis that the long latency of stretch reflexes in thumb and toe is because they are excited by slow-conducting afferents is made improbable by the finding that stretch reflexes with an equal or greater excess latency are also found in proximal arm muscles. 6. The long-latency stretch reflex in proximal muscles was seen most distinctly in a healthy subject who happened to have feeble or absent tendon jerks. In ordinary subjects there is often a large, short-latency, presumably spinal component of the stretch reflex in proximal muscles; and short-latency responses to halt and release are also seen, The significance of this spinal latency servo action in proximal muscles remains to be explored. 7. The Discussion argues that the available data on conduction time to and from the cerebral cortex are compatible with the hypothesis that the long-latency component of the stretch reflex uses a transcortical reflex arc, and that none of the experiments described in the present paper are inimical to this view.

Marsden, C D; Merton, P A; Morton, H B

1976-01-01

404

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

PubMed

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

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

2014-05-01

405

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

PubMed Central

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

2014-01-01

406

Glutamatergic neurotransmission from melanopsin retinal ganglion cells is required for neonatal photoaversion but not adult pupillary light reflex.  

PubMed

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

407

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

PubMed

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

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

2013-04-01

408

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

PubMed

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

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

2013-02-01

409

Pten deletion in RIP-Cre neurons protects against type 2 diabetes by activating the anti-inflammatory reflex.  

PubMed

Inflammation has a critical role in the development of insulin resistance. Recent evidence points to a contribution by the central nervous system in the modulation of peripheral inflammation through the anti-inflammatory reflex. However, the importance of this phenomenon remains elusive in type 2 diabetes pathogenesis. Here we show that rat insulin-2 promoter (Rip)-mediated deletion of Pten, a gene encoding a negative regulator of PI3K signaling, led to activation of the cholinergic anti-inflammatory pathway that is mediated by M2 activated macrophages in peripheral tissues. As such, Rip-cre(+) Pten(flox/flox) mice showed lower systemic inflammation and greater insulin sensitivity under basal conditions compared to littermate controls, which were abolished when the mice were treated with an acetylcholine receptor antagonist or when macrophages were depleted. After feeding with a high-fat diet, the Pten-deleted mice remained markedly insulin sensitive, which correlated with massive subcutaneous fat expansion. They also exhibited more adipogenesis with M2 macrophage infiltration, both of which were abolished after disruption of the anti-inflammatory efferent pathway by left vagotomy. In summary, we show that Pten expression in Rip(+) neurons has a critical role in diabetes pathogenesis through mediating the anti-inflammatory reflex. PMID:24747746

Wang, Linyuan; Opland, Darren; Tsai, Sue; Luk, Cynthia T; Schroer, Stephanie A; Allison, Margaret B; Elia, Andrew J; Furlonger, Caren; Suzuki, Akira; Paige, Christopher J; Mak, Tak W; Winer, Daniel A; Myers, Martin G; Woo, Minna

2014-05-01

410

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

411

Three cases of reflex sympathetic dystrophy in the lower extremity treated with lumbar sympathetic ganglion block  

Microsoft Academic Search

Reflex sympathetic dystrophy (RSD) is defined as follows: continuous pain in a portion of an extremity after trauma which may include fracture but does not involve a major nerve, associated with sympathetic hyperactivity\\

Kazumichi Yamada; Kazuo Ushijima; Masafumi Tashiro; Kumi Matsuyama; Yasuyuki Kakiuchi; Hisayoshi Miyazaki

1991-01-01

412

The depression of monosynaptically excited ?-motoneurons during vibration reflex by dimethylaminoadamantan (DMAA)  

Microsoft Academic Search

Summary The reflex amplitude of GS ?-motoneurons monosynaptically excited by Ia spindle afferents in cats with intercollicular decerebration was remarkably decreased in a parallel shift downwards from control by 10 mg\\/kg i.v. DMAA.

B. Mühlberg; K.-H. Sontag

1973-01-01