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Monoaminergic amygdalar mechanisms of conditioned reflexes of varied biological modality  

Microsoft Academic Search

Microinjection of dopamine and serotonin into the dorsomedial zones of the rat amygdala led to an increase in the latent period of conditioned defensive and motor-food reflexes, spontaneous motor activity, and the number of pushing movements and the magnitude of the food-grasping reflex. Noradrenalin had no effect on the parameters of the conditioned food reflex but facilitated the conditioned avoidance

I. V. Komissarov; A. N. Talalaenko



The conditioned reflex: Detectors and command neurons  

Microsoft Academic Search

The conditioned reflex is characterized by plasticity supporting bilateral selective connections between its input and output.\\u000a In simple nervous systems, input stimuli are represented by selective detectors connected to command neurons by plastic synapses\\u000a whose activity increases on learning and decreases on extinction. The process of associative learning occurs when excitation\\u000a of the detector and the command neuron coincide. Short-term

E. N. Sokolov; N. I. Nezlina



Calcitonin in reflex sympathetic dystrophy syndrome and other painful conditions  

Microsoft Academic Search

Salmon calcitonin (especially intranasal) provides an interesting analgesic effect in a series of painful conditions including reflex sympathetic dystrophy syndrome, adhesive capsulitis, ankylosing spondylitis, rheumatoid arthritis, vertebral crush fractures and metastasis, phantom limb pain, etc. In addition, in preliminary series, calcitonin shows an unexpected benefit to vasomotor changes and peptic ulcer. Yet the experience in these conditions is limited and

T Appelboom



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…

Giurfa, Martin; Malun, Dagmar



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



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



Conditioned-Reflex Estrasystole in Man.  

National Technical Information Service (NTIS)

It is certain that to the cerebral cortex belongs the determining role in the coordination of the nerve effects on the heart both in normal conditions and in a number of cases of disorders of the cardiac rhythm. It was seen that by through excitation the ...

I. A. Peimer



Calcitonin in reflex sympathetic dystrophy syndrome and other painful conditions.  


Salmon calcitonin (especially intranasal) provides an interesting analgesic effect in a series of painful conditions including reflex sympathetic dystrophy syndrome, adhesive capsulitis, ankylosing spondylitis, rheumatoid arthritis, vertebral crush fractures and metastasis, phantom limb pain, etc. In addition, in preliminary series, calcitonin shows an unexpected benefit to vasomotor changes and peptic ulcer. Yet the experience in these conditions is limited and needs confirmation. By comparison with the injectable, the intranasal route seems particularly interesting because of less undesirable effects, and a more rapid and probably more powerful analgesia. PMID:12008165

Appelboom, T



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


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



Recovery of conditioned reflexes in dogs after induction of hypothermia by means of head packs  

Microsoft Academic Search

Following the restoration of the body temperature in dogs, overcooled by head packs to the rectal temperature of 28°C, the secretory food and defensive respiratory conditioned reflexes are also completely restored. The process of restoration of the cerebral cortical function is 2–3 times slower than after external overcooling of the whole body. The restoration of defensive respiratory reflexes begins on

E. K. Aganyants; V. F. Novikov



Identification of Drosophila mutant with memory defects after acquisition of conditioned reflex suppression of courtship  

Microsoft Academic Search

Four lines were selected from a collection of 33 lines prepared by P insertion mutagenesis using a single-copy P-element system;\\u000a the males of these four lines showed memory defects after acquisition of conditioned reflex suppression of courting. In two\\u000a lines (P171 and P95), the dynamics of retention of the conditioned reflex in the repeated impregnated-female courting test\\u000a were similar to

N. G. Kamyshev; K. G. Iliadi; Yu. V. Bragina; E. V. Savvateeva-Popova; E. V. Tokmacheva; T. Preat



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


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



Contralateral and long latency effects of human biceps brachii stretch reflex conditioning  

Microsoft Academic Search

Results from previous studies on monkeys and human subjects have demonstrated that the biceps brachii spinal stretch reflex (SSR) can be operantly conditioned. The extent to which conditioning paradigms influence contralateral SSRs or longer latency responses in the same limb has not been examined. Nine subjects were given 10 training sessions to either increase or decrease the size of their

Steven L. Wolf; Richard L. Segal; Nancy D. Heter; Pamela A. Catlin



A mechanism of the diffuse component of the conditioned-reflex reaction  

Microsoft Academic Search

In investigating the dynamics of electrical activity in varous zones of the cerebral cortex it was noted that during the elaboration of defense and food conditioned reflexes in dogs in response to the action of unconditioned (defense and food) stimuli or conditioned sound signal oscillations resembling by their appearance induced potentials observed during the action of rhythmic light stimulation appeared

T. S. Naumova; N. N. Lyubimov; L. G. Trofimov



Conditioned Reflexes to Taste Stimuli in Children During First Months of Life.  

National Technical Information Service (NTIS)

The work is the continuation of a series of investigations directed toward the establishing of an age limit for the appearance of conditioned reflexes in a person. In the experiments described one was successful in establishing at what age there appear co...

T. P. Nemanova



[Effect of tryptophan and its metabolites on the conditioned reflex activity of the honeybee].  


The effect of tryptophane and its derivatives on the rate of elaboration and transformation of conditioned reflexes (CR) to odour, with alimentary reinforcement, was studied in wild bees under two conditions: free movement of the bee or its immobilization (stress situation), by means of genetic models (mutations, successive blocking stages of kynurenin path of tryptophane metabolism). It was shown that mutations eliciting accumulation of free tryptophane and serotonin in the hemolymph of the bees and creating a deficit of kynurenins accelerate the transformation of conditioned reflexes and aggravate the depression of conditioned activity usually elicited in wild bees by monotonous prolonged presentation of conditioned signal. The injections of tryptophane and serotonin (5 mg) produce the same action. Mutations, eliciting accumulation in the hemolymph of the kynurenins (kynurenin and 3-hydroxikynurenin) accelerate, in conditions of immobilization, the formation of conditioned reflexes and delay the process of their transformation, and also contribute to maintainance of a higher (in comparison with the norm) level of the conditioned activity under monotonous presentation of the signal. The same action is produced by the injection of 1 mcg kynurenin. PMID:6506871

Lopatina, N G; Dolotovskaia, L Z


Conditioning-specific reflex modification of the rabbit ( Oryctolagus cuniculus ) nictitating membrane response: US intensity effects  

Microsoft Academic Search

Conditioning-specific reflex modification (CRM) of the rabbit’s nictitating membrane response (NMR) describes changes in responding\\u000a to an unconditioned stimulus (US) when the rabbit is tested in the absence of the conditioned stimulus. Specifically, after\\u000a at least 3 days of tone-electrical stimulation pairings, responses to the US increase in size, especially at intensities weaker\\u000a than the training intensity. CRM is similar

Matthew A. Seager; Carrie A. Smith-Bell; Bernard G. Schreurs




Microsoft Academic Search

The ability of Aplysia and other gastropod molluscs to exhibit complex behaviors that can be modified by associative learning has encouraged us to search for an elementary behavior controlled by a simple and well analyzed neural circuit that also can be modified by this type of learning. Toward that end, we have now produced classical conditioning in the defensive siphon




The discovery of the principles of reinforcement, extinction, generalization, and differentiation of conditional reflexes in Pavlov’s laboratories  

Microsoft Academic Search

The discovery of reinforcement, extinction, generalization, and differentiation with the conditional reflex method in Pavlov’s\\u000a laboratories is described. Modern American introductory texts show that contemporary understanding of the experimental work\\u000a on conditioning in Pavlov’s laboratories is derived from a 1927 English translation of Pavlov’s lectures on the conditional\\u000a reflexes. The lectures present the discoveries topically, not chronologically. In contrast, this

George Windholz



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



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



Evidence for an Involvement of Associative Conditioning in Reflex Modification of the Acoustic Startle Response with Gaps in Background Noise.  

National Technical Information Service (NTIS)

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. Experiments were conducted with independent, naive groups of adult Long E...

K. M. Crofton K. F. Dean L. P. Sheets D. B. Peele



Heart rate changes during conditioning-specific reflex modification of the rabbit’s ( Oryctolagus cuniculus) nictitating membrane response  

Microsoft Academic Search

Conditioning-specific reflex modification (CRM) of the rabbit’s nictitating membrane response (NMR) involves changes in responding to an unconditioned stimulus (US) when the US is tested in the absence of the conditioned stimulus. Previous experiments have shown that CRM is a function of the type and intensity of the aversive US used during classical conditioning. As a result, it has been

Bernard G. Schreurs; Carrie A. Smith-Bell



Level of neuroactive steroids in the brain and sex-related peculiarities of formation and extinction of conditioned reflex in rats  

Microsoft Academic Search

Sex-related peculiarities of dynamics of brain sex steroids in the process of learning and extinction of the conditioned reflex\\u000a of passive avoidance have been studied in model experiment. Prior to learning of the conditioned reflex, female rats were\\u000a found to be distinguished by manifestation of anxiety and fear as compared with male rats. At formation of the conditioned\\u000a reflex, no

V. A. Sashkov; N. B. Selverova; E. D. Morenkov; I. V. Ermakova



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

PubMed Central

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

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



The optimizing action of the synthetic peptide Selank on a conditioned active avoidance reflex in rats.  


The actions of the synthetic heptapeptide preparation Selank on learning and memory processes in rats with initially low levels of learning ability were compared with those in normal rats, using a method based on acquisition of a conditioned active avoidance reflex, with repeated administration of peptide 15 min before the start of training sessions for four days. The effects of Selank (300 microg/kg) were compared with the effects of the nootrope piracetam (400 mg/kg). These experiments showed that Selank significantly activated the learning process in rats with initially poor learning ability, with effects apparent after first dose on training day 1. The effect progressively increased on repeated administration of Selank: the total number of correct solutions increased and the number of errors decreased (p < 0.05). The maximum optimizing activity of Selank on learning in normal rats was seen on day 3 of repeated administration and training, i.e., after formation of the initial consolidation phase. The dynamic features of the development of the activating action of Selank and piracetam were described. Comparison of the results obtained here with data on the anti-anxiety actions of Selank suggested potential for its use in optimizing mnestic functions in conditions of elevated emotional tension. PMID:14552529

Kozlovskii, I I; Danchev, N D



Neuronal correlates of forward and backward conditioned connections in a food-getting reflex formed to electrical stimulation of the lateral geniculate body  

Microsoft Academic Search

Conclusions 1.During a stable food-getting conditioned reflex to electrical stimulation of the lateral geniculate body basically two types of responses of visual cortical neurons are observed as a manifestation of the forward conditioned connection: conditioned-activating and conditioned-inhibitory.2.During extinction of the conditioned reflex the original neuronal pattern in the visual cortex was changed to the opposite, and was correlated with the

G. Kh. Merzhanova; V. M. Serdyuchenko



Differences in unconditioned and conditioned responses of the human withdrawal reflex during stance: Muscle responses and biomechanical data  

Microsoft Academic Search

The aim of this study was to characterize differences between unconditioned and classically conditioned lower limb withdrawal reflexes in young subjects during standing. Electromyographic activity in the main muscle groups and biomechanical signals from a strain-gauge-equipped platform on which subjects stood were recorded from 17 healthy subjects during unconditioned stimulus (US)-alone trials and during auditory conditioning stimuli (CS) and US

Thomas Kaulich; Wolfram Föhre; Dieter Friedhelm Kutz; Markus Gerwig; Dagmar Timmann; Florian Peter Kolb



Effect of injury to the serotoninergic and noradrenergic brain systems on food and defensive conditioned reflexes in rats  

Microsoft Academic Search

Conclusions 1.Electrolytic injury to the nuclei raphe impairs learning by rats with food reinforcement, as shown by a low initial level of performance of the conditioned-reflex reaction and inability of the animals to attain the criterion of learning. At the same time, formation of a conditioned active avoidance reaction by such animals is facilitated by comparison with the control.2.Electrolytic injury

E. A. Gromova; T. P. Semenova; O. N. Li; I. V. Nesterova



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

Microsoft Academic Search

Understanding the mechanisms of fear extinction has become increasingly important for treating a number of disorders, particularly post-traumatic stress disorder. Conditioning of rabbit heart rate (HR) is an established model for studying fear, yet little is known about procedures for extinguishing it other than repeated presentations of cue(s) associated with the fear-inducing event. The following study examined the effects of

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



Blood flow, blood pressure and heart rate changes accompanying hind leg flexion in conditional and unconditional reflexes  

Microsoft Academic Search

A flexor conditional reflex of the hind leg was formed in seven dogs. The US was an electrical shock on the skin of the paw.\\u000a The CS was a whistle. After stabilization of the CR, the following were recorded: flexor movement to US and to CS of the hind\\u000a leg, blood flow in the femoral artery on the same leg,

Juraj Antal; W. Horsley Gantt



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



Effects of activation of D1 dopamine receptors on extinction of a conditioned passive avoidance reflex and amnesia in aggressive and submissive mice  

Microsoft Academic Search

The studies reported here demonstrate the relationship between the effect of activation of D1 dopamine receptors on the reproduction\\u000a of a conditioned passive avoidance reflex during extinction and amnesia and the aggressive and submissive behavioral stereotypes.\\u000a During extinction, the D1 receptor agonist SKF 38393 at a dose of 5 mg\\/kg given before acquisition of the conditioned reflex\\u000a and on test

N. I. Dubrovina



The effect of operant-conditioning balance training on the down-regulation of spinal H-reflexes in a spastic patient.  


Spasticity in chronic hemiparetic stroke patients has primarily been treated pharmacologically. However, there is increasing evidence that physical rehabilitation can help manage hyper-excitability of reflexes (hyperreflexia), which is a primary contributor to spasticity. In the present study, one chronic hemiparetic stroke patient operantly conditioned the soleus H-reflex while training on a balance board for two weeks. The results showed a minimal decrease in the Hmax-Mmax ratio for both the affected and unaffected limb, indicating that the H-reflex was not significantly altered with training. Alternatively, paired-reflex depression (PRD), a measure of history-dependent changes in reflex excitability, could be conditioned. This was evident by the rightward shift and decreased slope of reflex excitability in the affected limb. The non-affected limb decreased as well, although the non-affected limb was very sensitive to PRD initially, whereas the affected limb was not. Based on these results, it was concluded that PRD is a better index of hyperreflexia, and this measurement could be more informative of synapse function than simple H-reflexes. This study presents a novel and non-pharmacological means of managing spasticity that warrants further investigation with the potential of being translated to the clinic. PMID:21945650

Hoseini, Najmeh; Koceja, David M; Riley, Zachary A



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



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.



[Forming of the visual cognitive structures in the monkey conditioned-reflex behaviour: the dependence on the sensory information].  


In monkeys, changes in size and shape of figures led to a significant decrease of correct solutions in training and a considerable increase of refusals from solution of tasks as well as the time of their motor response. The invariance of differentiation in this case was achieved after additional training. The data obtained show that, based on the stimulus sensory processing in conditioned-reflex training, in the long-term memory some differentiating signs are formed: the cognitive structures (the functional neurophysiological mechanisms) maintaining the classification of visual images. With these structures, temporary conditioned connection will be established. Their formation will be determined by the type of sensory information and provided for by existence in the long-term memory of separate subsystems for spatial as well as non-spatial information. PMID:18383735

Dudkin, K N; Chueva, I V



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


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

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



[A computer analysis of EEG intersignal reactions during the the acquisition of conditioned motor-food reflexes in dogs].  


Background electric activity was studied of different neocortex areas in interstimulus intervals at the stage of generalization during elaboration of motor alimentary conditioned reflexes in dogs. For this stage the appearance is typical of short-term (0.1-0.3 s) packs of high frequencies (above 40 osc./s) significantly exceeding the adjacent initial background by frequency and amplitude (along side with motor interstimulus reactions). The index of specific variation, elaborated by us, allowed to single out this EEG pattern in the initial realizations of the background activity during their input in the computer. With the purpose of further evaluation of the above phenomenon parameters non-standard approaches of computer analyses were used, directed to decomposition of the EEG curve into the system of oscillations and receipt of corresponding amplitudes frequencies distributions (maps). It was shown, the described high frequencies packs were localized on these maps in definite sufficiently compact places. PMID:1369561

Dumenko, V N; Kozlov, M K


Relationship between the types of behavioral reaction in a conditioned shake-off reflex and neocortical lateralization.  


The nature of the spike activity and interhemisphere interactions of neurons in the parietal cortex (somatosensory representation of the ear) during the intersignal period before active shake-off and passive (freezing) reactions to stimuli was studied in rabbits after acquisition of a conditioned defensive escape reflex. Before passive reactions, in contrast to the situation before active shake-off, there were increases in right-sided influences on cells in the left hemisphere with delays of up to 100 msec, leading to asymmetry in interhemisphere interactions with right-sided dominance. Passive reactions were preceded by increases in the extent of frequencies in the delta range in the spike activity of individual neurons and in interactions between pairs of cells. These data provide evidence that the existence and nature of interhemisphere asymmetry before stimulation is one of the factors determining the passive or active type of behavioral reaction and reflecting the level of activation of the cortex. PMID:18802771

Pavlova, I V; Vanetsian, G L



Conditioned food aversion in Suncus murinus (house musk shrew) — a new model for the study of nausea in a species with an emetic reflex  

Microsoft Academic Search

The lack of a small animal model with an emetic reflex in which the relationship between conditioned food aversion and emesis could be investigated prompted a study of the insectivore, Suncus murinus (the house musk shrew). A novel food (either tuna or chicken cat food) was paired (C+) with a single exposure to either nicotine (4 mg\\/kg sc), motion (1

Julia E Smith; Mark I Friedman; Paul L. R Andrews



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

Microsoft Academic Search

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

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



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



Discrimination Learning and Reversal of the Conditioned Eyeblink Reflex in a Rodent Model of Autism  

PubMed Central

Offspring of rats exposed to valproic acid (VPA) on Gestational Day (GD) 12 have been advocated as a rodent model of autism because they show neuron loss in brainstem nuclei and the cerebellum resembling that seen in human autistic cases [20, 37]. Studies of autistic children have reported alterations in acquisition of classical eyeblink conditioning [40] and in reversal of instrumental discrimination learning [9]. Acquisition of discriminative eyeblink conditioning depends on known brainstem-cerebellar circuitry whereas reversal depends on interactions of this circuitry with the hippocampus and prefrontal cortex. In order to explore behavioral parallels of the VPA rodent model with human autism, the present study exposed pregnant Long-Evans rats to 600 mg/kg VPA on GD12 [cf. 37] and tested their offspring from PND26-31 on discriminative eyeblink conditioning and reversal. VPA rats showed faster eyeblink conditioning, consistent with studies in autistic children [40]. This suggests that previously reported parallels between human autism and the VPA rodent model with respect to injury to brainstem-cerebellar circuitry [37] are accompanied by behavioral parallels when a conditioning task engaging this circuitry is used. VPA rats also showed impaired reversal learning, but this likely reflected “carry-over” of enhanced conditioning during acquisition rather than a reversal learning deficit like that seen in human autism. Further studies of eyeblink conditioning in human autism and in various animal models may help to identify the etiology of this developmental disorder.

Stanton, Mark E.; Peloso, Elizabeth; Brown, Kevin L.; Rodier, Patricia



Incubation of Conditioning-Specific Reflex Modification: Implications for Post Traumatic Stress Disorder  

PubMed Central

Incubation of fear has been used to account for the delayed manifestation of symptoms of fear and anxiety including the delayed onset of Post Traumatic Stress Disorder (PTSD). We have shown the utility of classical conditioning-specific modification of the rabbit nictitating membrane response (NMR) as a model of PTSD. This modification includes an exaggeration in the size and a change in the timing of the unconditioned NMR after several days of classical conditioning. To assess the effects of incubation on conditioning-specific modification, we measured changes in responding as a function of the time between classical conditioning and NMR testing. After just one day of classical conditioning resulting in modest levels of learning, increases in response size were an inverted-U shaped function of days of incubation with little if any change occurring one and ten days after training but significant change occurring after six days. The incubation effect persisted for a week. An unpaired control group showed no change in the size of the response confirming the incubation effect was associative. The results bear a striking resemblance to symptoms of PTSD that do not always occur immediately after trauma and become exacerbated over time and then persist. They point to a window when incubation can exacerbate symptoms and speak to the vulnerability of re-experiencing trauma too soon. This could be a serious problem for military or emergency personnel recalled to combat or a disaster site without sufficient time to deal with the effects of their initial experiences.

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



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.



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.



Adopting the good reFLEXes when generating conditional alterations in the mouse genome  

Microsoft Academic Search

Major advances have been made in the use of the Cre\\/loxP system for conditional gene targeting in the mouse. By combining the ability of Cre recombinase to invert or excise a DNA\\u000a fragment, depending upon the orientation of the flanking loxP sites, and the use of wild-type loxP and variant lox511 sites, we devised an efficient and reliable Cre-mediated genetic

Frank Schnütgen; Norbert B. Ghyselinck



Long-term facilitation of nociceptive withdrawal reflexes following low-frequency conditioning electrical stimulation: a new model for central sensitization in humans.  


Central sensitization is believed to be one of the key mechanisms behind chronic pain conditions, and several models have been developed in order to characterize this phenomenon in humans. One of these models relies on conditioning electrical stimulation to elicit long-lasting effects on the nociceptive system. The aim of this study was to evaluate these effects using an objective electrophysiological measurement, the nociceptive withdrawal reflex (NWR). Long-term changes in spinal nociception after high- and low-frequency conditioning electrical stimulation were assessed in 13 healthy volunteers. Perceptual intensity ratings to mechanical stimuli and blood flow variations were assessed in the conditioned area (dorsum of the foot) and surroundings. To evaluate the excitability of the nociceptive system, the NWR was elicited within the same innervation area (superficial peroneal nerve) at graded stimulation intensities and recorded in the hamstrings. Following low-frequency stimulation, an intensity-independent long-lasting facilitation of the NWR was observed, with a significant increase in the reflex size (average of 31+/-4%, p<0.001) and in the number of reflexes (average increase of 22+/-10%, p<0.01), accompanied by a significant increase in the blood flow (average increase of 40+/-10%, p<0.001). These findings suggest that activity-dependent central sensitization can be elicited using conditioning electrical stimulation with a stimulation frequency that lies within the physiological firing range of primary afferents, and that it can be objectively assessed in humans using the NWR. PMID:20110183

Biurrun Manresa, José A; Mørch, Carsten D; Andersen, Ole K



Formation of cognitive structures in conditioned-reflex behavior in monkeys: Relationship with type of visual information.  


The characteristics of learning processes and long-term memory (LTM) were studied in rhesus macaques discriminating visual stimuli (geometrical figures of different shapes, sizes, and orientations, and with different spatial relationships between image components). Trained monkeys were tested for the ability to perform invariant recognition after stimulus transformation, i.e., changes in size, shape, number of objects, and spatial relationships. Analysis of behavioral characteristics (correct solutions, refusals to decide, motor response times) revealed differences associated with the type of visual information. When monkeys discriminated between black and white geometrical figures of different shapes and orientations, as well as black-and-white figures with different shapes or orientations, the learning time was short and transformation of the stimuli had no effect on correct solutions: there was complete transfer of learning. When monkeys discriminated figures of different sizes or complex images with different spatial relationships, the learning time was significantly greater. Changes in the size and shape of figures led to significant reductions in correct solutions and significant increases in refusals to solve the task and in motor reaction times. Invariance of discrimination in this case appeared after additional training. The results obtained here showed that in conditioned reflex learning, the sensory processing of stimuli has the result that discriminatory features are formed in LTM, i.e., cognitive structures (functional neurophysiological mechanisms), these supporting the classification of visual images. The temporal conditioned link of the executive reaction is established with these. Their formation is determined by the type of sensory information and the existence in LTM of separate subsystems for spatial and non-spatial information. PMID:19140004

Dudkin, K N; Chueva, I V



Dopamine D 1 Receptors Regulate the Extracellular Citrulline Level in the Nucleus Accumbens During Performance of a Conditioned Reflex Fear Reaction  

Microsoft Academic Search

Intracerebral microdialysis studies on Sprague–Dawley rats using HPLC showed that performance of a conditioned reflex fear\\u000a reaction was accompanied by an increase in the extracellular citrulline (a co-product of nitric oxide synthesis) level in\\u000a the nucleus accumbens. Administration of the selective D1 receptor antagonist SCH-23390 (100 ?M) into the nucleus accumbens had no long-lasting effect on the extracellular citrulline\\u000a level in

N. B. Saul’skaya; N. V. Fofonova



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.



Emotion, Attention, and the Startle Reflex  

Microsoft Academic Search

This theoretical model of emotion is based on research using the startle-probe methodology. It explains inconsistencies in probe studies of attention and fear conditioning and provides a new approach to emotional perception, imagery, and memory. Emotions are organized biphasically, as appetitive or aversive (defensive). Reflexes with the same valence as an ongoing emotional state are augmented; mismatched reflexes are inhibited.

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



Certain Peculiarities of the Unconditioned Salivary Reflex in Dogs after Conditioned Light and Sound Stimuli of Various Strengths.  

National Technical Information Service (NTIS)

The fact that conditioned stimuli influence the course of unconditioned secretion is well known. It has been customary to explain the difference in the course of unconditioned secretion after application of so-called strong and weak conditioned stimuli in...

L. N. Andreev



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



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



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.



Epidemiology of reflex syncope  

Microsoft Academic Search

Cost-effective diagnostic approaches to reflex syncope require knowledge of its frequency and causes in different age groups. For this purpose we reviewed the available literature dealing with the epidemiology of reflex syncope. The incidence pattern of reflex syncope in the general population and general practice is bimodal with peaks in teenagers and in the elderly. In the young almost all

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



Embodied Self-Reflexivity  

ERIC Educational Resources Information Center

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

Pagis, Michal



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



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



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

Microsoft Academic Search

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

Mary Pendery; Irving Maltzman



Effects of operantly conditioning the amplitude of the P200 peak of the SEP on pain sensitivity and the spinal nociceptive withdrawal reflex in humans.  


This study attempted to replicate and extend earlier work that reported that the amplitude of the P200 peak of the human somatosensory evoked potential (SEP) can be increased and decreased when reward is made contingent upon change and that these changes are accompanied by alterations in pain sensitivity. Twenty-one subjects were able to make the amplitude of the P200 peak evoked by sural nerve stimulation larger during increased training (up-training) than during decreased training (down-training). There were no differences in the sural nerve compound action potential between up-training and down-training. This finding demonstrates that the change in P200 amplitude was not due to a change in stimulus efficacy, but rather to a change within the central nervous system. Subjective pain ratings and a nociceptive spinal reflex were the same in up-training as in down-training. Thus, conditioned changes in P200 amplitude do not alter pain sensitivity. PMID:8936394

Dowman, R



Classical Conditioning Components of the Orienting Reflex to Words Using Innocuous and Noxious Unconditioned Stimuli Under Different Conditioned Stimulus-Unconditioned Stimulus Intervals  

ERIC Educational Resources Information Center

|Concerns the examination of conditioned stimulus--unconditioned stimulus (CS--UCS) intervals of different lengths. Demonstrates the feasibility of using a forewarned reaction time procedure with an innocuous imperative stimulus for the investigation of classical conditioning. (Editor/RK)|

Maltzman, Irving; And Others



Reflex control of immunity  

Microsoft Academic Search

Inflammation can cause damage and even death. What controls this primitive and potentially lethal innate immune response to injury and infection? Molecular and neurophysiological studies during the past decade have revealed a pivotal answer: immunity is coordinated by neural circuits that operate reflexively. The afferent arc of the reflex consists of nerves that sense injury and infection. This activates efferent

Kevin J. Tracey



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.



The parallel programming of voluntary and reflexive saccades  

Microsoft Academic Search

A novel two-step paradigm was used to investigate the parallel programming of consecutive, stimulus-elicited (‘reflexive’) and endogenous (‘voluntary’) saccades. The mean latency of voluntary saccades, made following the first reflexive saccades in two-step conditions, was significantly reduced compared to that of voluntary saccades made in the single-step control trials. The latency of the first reflexive saccades was modulated by the

Robin Walker; Eugene McSorley



Anatomy and neuro-pathophysiology of the cough reflex arc  

PubMed Central

Coughing is an important defensive reflex that occurs through the stimulation of a complex reflex arc. It accounts for a significant number of consultations both at the level of general practitioner and of respiratory specialists. In this review we first analyze the cough reflex under normal conditions; then we analyze the anatomy and the neuro-pathophysiology of the cough reflex arc. The aim of this review is to provide the anatomic and pathophysiologic elements of evaluation of the complex and multiple etiologies of cough.



Brainstem reflex circuits revisited.  


Our current understanding of brainstem reflex physiology comes chiefly from the classic anatomical-functional correlation studies that traced the central circuits underlying brainstem reflexes and establishing reflex abnormalities as markers for specific areas of lesion. These studies nevertheless had the disadvantage of deriving from post-mortem findings in only a few patients. We developed a voxel-based model of the human brainstem designed to import and normalize MRIs, select groups of patients with or without a given dysfunction, compare their MRIs statistically, and construct three-plane maps showing the statistical probability of lesion. Using this method, we studied 180 patients with focal brainstem infarction. All subjects underwent a dedicated MRI study of the brainstem and the whole series of brainstem tests currently used in clinical neurophysiology: early (R1) and late (R2) blink reflex, early (SP1) and late (SP2) masseter inhibitory reflex, and the jaw jerk to chin tapping. Significance levels were highest for R1, SP1 and R2 afferent abnormalities. Patients with abnormalities in all three reflexes had lesions involving the primary sensory neurons in the ventral pons, before the afferents directed to the respective reflex circuits diverge. Patients with an isolated abnormality of R1 and SP1 responses had lesions that involved the ipsilateral dorsal pons, near the fourth ventricle floor, and lay close to each other. The area with the highest probabilities of lesion for the R2-afferent abnormality was in the ipsilateral dorsal-lateral medulla at the inferior olive level. SP2 abnormalities reached a low level of significance, in the same region as R2. Only few patients had a crossed-type abnormality of SP1, SP2 or R2; that of SP1 reached significance in the median pontine tegmentum rostral to the main trigeminal nucleus. Although abnormal in 38 patients, the jaw jerk appeared to have no cluster location. Because our voxel-based model quantitatively compares lesions in patients with or without a given reflex abnormality, it minimizes the risk that the significant areas depict vascular territories rather than common spots within the territory housing the reflex circuit. By analysing statistical data for a large cohort of patients, it also identifies the most frequent lesion location for each response. The finding of multireflex abnormalities reflects damage of the primary afferent neurons; hence it provides no evidence of an intra-axial lesion. The jaw jerk, perhaps the brainstem reflex most widely used in clinical neurophysiology, had no apparent topodiagnostic value, probably because it depends strongly on peripheral variables, including dental occlusion. PMID:15601661

Cruccu, G; Iannetti, G D; Marx, J J; Thoemke, F; Truini, A; Fitzek, S; Galeotti, F; Urban, P P; Romaniello, A; Stoeter, P; Manfredi, M; Hopf, H C



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.  


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



Optimization of a two-stages electrostatic reflex ion source  

Microsoft Academic Search

In our argon, oxygen, or nitrogen broad beam ion source, 80 mm in diameter, which is either an electrostatic reflex ion source, or a magnetic and electrostatic reflex ion source, the hot filament has been replaced by a carefully optimized microwave plasma (MP) cathode under the electron cyclotron resonance condition. Different geometries of antennae in which the microwave transverse electric

A. Farchi; L. Wartski; F. Boukari; V. Roy; Ph. Coste; J. Aubert



What functions do reflexes serve during human locomotion?  

Microsoft Academic Search

Studies on the reflex modulation of vertebrate locomotion have been conducted in many different laboratories and with many different preparations: for example, lamprey swimming, bird flight, quadrupedal walking in cats and bipedal walking in humans. Emerging concepts are that reflexes are task-, phase- and context-dependent. To function usefully in a behaviour such as locomotion wherein initial conditions change from step

E. Paul Zehr; Richard B. Stein



Hyperekplexia and stiff-man syndrome: abnormal brainstem reflexes suggest a physiological relationship  

PubMed Central

Background and objectives: Hyperekplexia and the stiff-man syndrome (SMS) are both conditions with exaggerated startle suggesting abnormal brainstem function. Investigation of brainstem reflexes may provide insight into disturbed reflex excitation and inhibition underlying these movement disorders. Patients and methods: Using four-channel EMG, we examined four trigeminal brainstem reflexes (monosynaptic masseter, masseter inhibitory, glabella, and orbicularis oculi blink reflexes) and their spread into pericranial muscles in five patients with familial hyperekplexia (FH), two with acquired hyperekplexia (AH), 10 with SMS, and 15 healthy control subjects. Results: Both FH/AH and SMS patients had abnormal propagation of brainstem reflexes into pericranial muscles. All patients with hyperekplexia showed an abnormal short-latency (15–20 ms) reflex in the trapezius muscle with a characteristic clinical appearance ("head retraction jerk") evoked by tactile or electrical stimulation of the trigeminal nerve, but normal monosynaptic masseter reflexes. Inhibitory brainstem reflexes were attenuated in some FH/AH patients. Four of 10 patients with SMS had similar short-latency reflexes in the neck muscles and frequently showed widespread enhancement of other excitatory reflexes, reflex spasms, and attenuation of inhibitory brainstem reflexes. Conclusion: Reflex excitation is exaggerated and inhibition is attenuated in both stiff-man syndrome and familial or acquired hyperekplexia, indicating a physiological relationship. Reflex transmission in the brainstem appears biased towards excitation which may imply dysfunction of inhibitory glycinergic or GABAergic interneurons, or both.

Khasani, S; Becker, K; Meinck, H



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



Differential Effects of a Distant Noxious Stimulus on Hindlimb Nociceptive Withdrawal Reflexes in the Rat.  


Recent studies indicate that the nociceptive withdrawal reflexes to individual muscles are evoked by separate reflex pathways. The present study examines whether nociceptive withdrawal reflexes to different muscles are subject to differential supraspinal control in rats. A distant noxious stimulus was used to activate a bulbospinal system which selectively inhibits 'multireceptive' neurons (i.e. neurons receiving excitatory tactile and nociceptive inputs) in the dorsal horn of the spinal cord. Withdrawal reflexes, recorded with electromyographic techniques in single hindlimb muscles, were evoked by standardized noxious pinch. Thirty-seven rats, anaesthetized with halothane and nitrous oxide, were used. Whereas withdrawal reflexes to the extensor digitorum longus and brevis, tibialis anterior and biceps posterior muscles were strongly inhibited, reflexes to interossei muscles were potentiated during noxious pinch of the nose. Reflexes to peronei muscles were not significantly changed. The effects on the reflexes usually had an onset latency of <0.5 s and outlasted the conditioning stimulation by up to 2 s. The monosynaptic la reflex to the deep peroneal nerve, innervating dorsiflexors of the digits and ankle, was not significantly changed during noxious pinch of the nose. Hence, the inhibitory effects on the hindlimb withdrawal reflexes induced by the conditioning stimulation were presumably exerted on reflex interneurons. It is concluded that nociceptive withdrawal reflexes to different hindlimb muscles are differentially controlled by descending pathways activated by a distant noxious stimulus. The results support our previous conclusion that there are separate nociceptive withdrawal reflex pathways to different hindlimb muscles. PMID:12106328

Kalliomäki, J.; Schouenborg, J.; Dickenson, A. H.



Depression of the human nociceptive withdrawal reflex by segmental and heterosegmental intramuscular electrical stimulation  

Microsoft Academic Search

ObjectiveTo investigate the effects of intramuscular electrical conditioning in the modulation of nociceptive withdrawal reflex (NWR) and further to determine what muscle afferents are involved in the modulation of the nociceptive withdrawal reflex and the sites along the reflex pathway where the NWR modulation occurs in healthy humans.

Hong-You Ge; Thomas Collet; Carsten Dahl Mørch; Lars Arendt-Nielsen; Ole Kæseler Andersen



Reflexivity in Pigeons  

ERIC Educational Resources Information Center

A recent theory of pigeons' equivalence-class formation (Urcuioli, 2008) predicts that reflexivity, an untrained ability to match a stimulus to itself, should be observed after training on two "mirror-image" symbolic successive matching tasks plus identity successive matching using some of the symbolic matching stimuli. One group of pigeons was…

Sweeney, Mary M.; Urcuioli, Peter J.



Eponyms in cardiopulmonary reflexes.  


Heart rate, blood pressure, and vascular tone, as well as ventilator drive, respiratory rate, and breathing pattern, are, at least in part, under the control of specific reflexes. These reflexes are mediated by a complex network of baroreceptors and chemoreceptors in the arterial system of the carotids, aorta, and left heart, including receptors in the left atrium, the ventricle, and the coronary arteries; irritants in the upper airways and stretch receptors in the lower airways; juxtacapillary-located nonmyelinated fibers in the alveoli and in the bronchial arterial system; and muscle spindles that evoke changes in the membrane potential upon alteration of sarcolemmal tension. Some of these reflexes, usually named after the first individual to describe them, have spread as eponyms into propaedeutic education and clinical work. Because these euphonic eponyms are enigmatic to most clinicians today, this article is intended to provide a short overview of these reflexes, including the historical context of their describers. As evidenced by their clinical implications, the eponyms discussed are revealed to be more than curiosities taught during undergraduate medical education. PMID:24027790

Arrigo, Mattia; Huber, Lars C



Physiology of Oculocardiac reflex  

Microsoft Academic Search

The oculocardiac reflex slows the heart action, giving extraordinary rest to this vital organ. It stops decay in outer and inner organs, enabling the body cells to brim over with lifeforce. The calming effect on the heart switches off the energy in the five sense- telephones of touch, smell, taste, hearing and sight. It also reduces breathing to a minimum.

Varun Malhotra; Arjun VS; Swarnima Basu; Harish Joshi; RaviShankar P


Possible startle response contamination of the spinal nociceptive withdrawal reflex.  


The objective of this study was to examine the possibility that the spinal nociceptive withdrawal reflex, otherwise known as the RIII reflex, is contaminated by the startle response, which is a non-pain-related supraspinal response. Startle response contamination of the RIII reflex would seriously compromise the RIIIs ability to measure spinal nociceptive processes in man, since a change in the startle response affecting EMG amplitude in the RIII latency range would be erroneously interpreted as a change in a spinal nociceptive process. EMG responses evoked by electrical stimulation of the sural nerve were recorded from the orbicularis oculi, neck, biceps, and biceps femoris muscles in 31 healthy human volunteers. The startle response was elicited under conditions often used to record the RIII reflex. Procedures are described that will completely eliminate the startle response. Comparisons between subjects that did and did not elicit a startle response revealed that the startle does not appear to significantly contaminate the biceps femoris RIII reflex, at least when performing group comparisons. There are, however, situations not dealt with in this study in which the startle might significantly contaminate the RIII reflex, such as patients with pre-existing negative emotional states, experimental procedures that induce fear and/or anxiety, and single case studies. It is important, therefore, that investigators using the RIII reflex be cognizant of the startle response and take appropriate precautions to monitor and if necessary eliminate the startle before attributing a change in the RIII reflex to a spinal nociceptive process. PMID:1608645

Dowman, R



Postural and eye-blink indices of the defensive startle reflex  

Microsoft Academic Search

Postural and eye-blink reactions to acoustic startle probes were examined in 24 volunteers, who completed two blocked conditions (baseline, startle). A postural reaction during the startle condition demonstrated a reflexive movement in the anterior–posterior direction, which was not observed during the baseline condition. This reflexive response was positively associated with the eye-blink reflex, such that larger blink magnitude related to

Charles H. Hillman; Elizabeth T. Hsiao-Wecksler; Karl S. Rosengren



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


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



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



Reflex sympathetic dystrophy.  


Reflex sympathetic dystrophy, causalgia, Sudeck's atrophy, shoulder-hand syndrome, and transient osteoporosis represent a spectrum of sympathetic disturbances which typically present with regional findings. They are often pauciarticular in distribution and uniquely sensitive to timely therapeutic intervention and to preventative measures. Clinical and radiologic appearances are quite characteristic. Thermographic examination provides a valuable tool for monitoring the therapeutic response. The major factor in therapeutic efficacy is aggressive physical therapy. Although therapeusis has been facilitated by a multitude of agents, therapeutic resistance is unfortunately the circumstance, when intervention is delayed. PMID:2285753

Rothschild, B



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.



Demand functions and reflexivity  

NASA Astrophysics Data System (ADS)

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

Polyrakis, Ioannis A.



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


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

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


The Hoffmann Reflex: Methodologic Considerations and Applications for Use in Sports Medicine and Athletic Training Research  

PubMed Central

Objective: To discuss the proper methods used to elicit the Hoffmann reflex (H-reflex) and to present different situations in which this tool can be used in sports medicine research. Data Sources: We searched MEDLINE and SPORT Discus from 1960 to 2004 using the key words Hoffmann reflex, H-reflex, and methodology. The remaining citations were collected from references of similar papers. Data Synthesis: Numerous authors have used the H-reflex as a tool to examine neurologic conditions. However, few have used the H-reflex to examine neuromuscular impairments after sport injuries. Several studies were available describing the appropriate methods to elicit the H-reflex and examining the reliability of this measurement in different muscles. Conclusions/Recommendations: The H-reflex is a valuable tool to evaluate neurologic function in various populations. However, because of the sensitivity of this measurement to extraneous factors, care must be taken when eliciting the H-reflex. We discuss recommendations on how to elicit the H-reflex and how to appropriately present methods in a manuscript.

Ingersoll, Christopher D.; Hoffman, Mark A.



The Relationship between MOC Reflex and Masked Threshold  

PubMed Central

Otoacoustic emission (OAE) amplitude can be reduced by acoustic stimulation. This effect is produced by the medial olivocochlear (MOC) reflex. Past studies have shown that the MOC reflex is related to listening in noise and attention. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold was investigated in 19 adults. Detection thresholds were determined for a 1000-Hz, 300-ms tone presented simultaneously with one repetition of a 300-ms masker in an ongoing train of 300-ms masker bursts at 600-ms intervals. Three masking conditions were tested: 1) broadband noise 2) a fixed-frequency 4-tone complex masker and 3) a random-frequency 4-tone complex masker. Broadband noise was expected to produce energetic masking and the tonal maskers were expected to produce informational masking in some listeners. DPOAEs were recorded at fine frequency interval from 500 to 4000 Hz, with and without contralateral acoustic stimulation. MOC reflex strength was estimated as a reduction in baseline level and a shift in frequency of DPOAE fine-structure maxima near 1000-Hz. MOC reflex and psychophysical testing were completed in separate sessions. Individuals with poorer thresholds in broadband noise and in random-frequency maskers were found to have stronger MOC reflexes.

Garinis, Angela; Werner, Lynne; Abdala, Carolina



Glottic closure reflex: control mechanisms.  


Reflex glottic closure is a dominant and stable reflex produced by stimulation of the superior laryngeal nerve. Its precise execution is basic to successful sphincteric protection of the lower airway. In exaggerated form, it produces life-threatening laryngospasm. Clearly, reflex glottic closure and laryngospasm are facilitated by: a) expiratory phase; b) decreased arterial partial pressure of carbon dioxide (pCO2); c) increased arterial partial presure of oxygen (pO2); and d) negative intrathoracic pressure. On the other hand, both reflex glottic closure and laryngospasm are inhibited by; a) inspiratory phase; b) increased arterial pCO2; c) decreased arterial pO2; and d) positive intrathoracic pressure. A clear understanding of laryngeal adductor control is an essential first step in the therapeutic modification of abnormal laryngeal closure and laryngospasm. PMID:6774650

Ikari, T; Sasaki, C T


Volitional control of reflex cough  

PubMed Central

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

Bolser, Donald C.; Davenport, Paul W.



Impaired cough reflex in patients with recurrent pneumonia  

Microsoft Academic Search

Background: A substantial proportion of patients with recurrent pneumonia do not have an apparent underlying condition, but they may have unknown defects in host defence mechanisms such as cough reflex.Methods: Capsaicin cough sensitivity was measured in seven patients with recurrent pneumonia but no underlying condition. Recurrent pneumonia was defined as at least two episodes of pneumonia in 1 year, or

A Niimi; H Matsumoto; T Ueda; M Takemura; K Suzuki; E Tanaka; K Chin; M Mishima; R Amitani



Peroneus longus stretch reflex amplitude increases after ankle brace application  

PubMed Central

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

Cordova, M; Ingersoll, C



A simulation study of reflex instability in spasticity: origins of clonus  

Microsoft Academic Search

Clonus is defined as an involuntary rhythmic muscle contraction that generally occurs in people who have sustained lesions involving descending motor pathways in the neuraxis, and is usually accompanied by other signs of reflex hyperexcitability such as spasticity. This paper hypothesizes that clonus arises when two conditions occur simultaneously: (1) the reflex pathway contains long delay times (implying innervation of

Joseph M. Hidler; W. Zev Rymer



Taking control of reflexive social attention.  


Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the case that top-down factors may modulate the activation of IT cells. Here we examined behaviorally whether reflexive social orienting is purely automatic or sensitive to top-down modulation. Participants were shown an ambiguous stimulus that could be perceived either as representing EYES or a CAR. In we demonstrated between groups that an automatic shift of attention, equivalent to that triggered by a schematic FACE, occurred only when the stimulus was referred to as possessing EYES. In all participants received the EYES and CAR conditions. When the stimulus was first referred to as a CAR and then as EYES, an attentional shift was only present for the EYES condition. However, when the stimulus was first referred to as possessing EYES, and then later as a CAR, attentional shifts were observed for both conditions. These data indicate that the emergence of a reflexive social attention effect is influenced by top-down mechanisms but in an asymmetrical manner. Top-down processes appear to be effective for triggering IT involvement, that is, for perceiving a stimulus as a face, which produces the social attention effect. But top-down mechanisms are ineffective once IT involvement has been triggered. That is, once a stimulus has been seen as having eyes, it continues to be seen that way, and accordingly, the social attention effect persists. PMID:15617667

Ristic, Jelena; Kingstone, Alan



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.



Phase-specific modulation of the soleus H-reflex as a function of threat to stability during walking  

Microsoft Academic Search

The purpose of the present study was to determine whether the soleus H-reflex is modulated with changes in the level of postural\\u000a threat during walking. H-reflexes were tested at four points in the step cycle when subjects walked in 5 conditions representing\\u000a different levels of postural threat. H-reflexes were significantly increased in amplitude at heelstrike in conditions of increased\\u000a postural

E. M. Krauss; J. E. Misiaszek



Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke  

PubMed Central

Patterns of stereotyped muscle coactivation, clinically referred to as synergies, emerge following stroke and impair arm function. Although researchers have focused on cortical contributions, there is growing evidence that altered stretch reflex pathways may also contribute to impairment. However, most previous reflex studies have focused on passive, single-joint movements without regard to their coordination during volitional actions. The purpose of this study was to examine the effects of stroke on coordinated activity of stretch reflexes elicited in multiple arm muscles following multijoint perturbations. We hypothesized that cortical injury results in increased stretch reflexes of muscles characteristic of the abnormal flexor synergy during active arm conditions. To test this hypothesis, we used a robot to apply position perturbations to impaired arms of 10 stroke survivors and dominant arms of 8 healthy age-matched controls. Corresponding reflexes were assessed during volitional contractions simulating different levels of gravitational support, as well as during voluntary flexion and extension of the elbow and shoulder. Reflexes were quantified by average rectified surface electromyogram, recorded from eight muscles spanning the elbow and shoulder. Reflex coordination was quantified using an independent components analysis. We found stretch reflexes elicited in the stroke group were significantly less sensitive to changes in background muscle activation compared with those in the control group (P < 0.05). We also observed significantly increased reflex coupling between elbow flexor and shoulder abductor–extensor muscles in stroke subjects relative to that in control subjects. This increased coupling was present only during volitional tasks that required elbow flexion (P < 0.001), shoulder extension (P < 0.01), and gravity opposition (P < 0.01), but not during the “no load” condition. During volitional contractions, reflex amplitudes scaled with the level of impairment, as assessed by Fugl-Meyer scores (r2 = 0.63; P < 0.05). We conclude that altered reflex coordination is indicative of motor impairment level and may contribute to impaired arm function following stroke.

Ravichandran, Vengateswaran J.; Krutky, Matthew A.; Perreault, Eric J.



[Clinical relevance of cardiopulmonary reflexes in anesthesiology].  


The baroreflex, chemoreflex, pulmonary reflexes, Bezold-Jarisch and Bainbridge reflexes and their interaction with local mechanisms, are a demonstration of the richness of cardiovascular responses that occur in human beings. As well as these, the anesthesiologist must contend with other variables that interact by attenuating or accentuating cardiopulmonary reflexes such as, anesthetic drugs, surgical manipulation, and patient positioning. In the present article we review these reflexes and their clinical relevance in anesthesiology. PMID:23121709

Guerri-Guttenberg, R A; Siaba-Serrate, F; Cacheiro, F J



Reflexive practice: To enhance student learning  

Microsoft Academic Search

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

Joanne Roebuck



Adapting reflexes controlling the human posture  

Microsoft Academic Search

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

L. M. Nashner



Cutaneous inhibitory receptive fields of withdrawal reflexes in the decerebrate spinal rat.  

PubMed Central

1. The inhibitory cutaneous input to the withdrawal reflex pathways to single hindlimb muscles was investigated in decerebrate spinal rats (n = 53) using electromyography. 2. Withdrawal reflexes in the peronei, extensor digitorum longus and tibialis anterior muscles of the leg were strongly inhibited by conditioning mechanical, thermal (CO2 laser) and intracutaneous electrical stimulation of specific skin areas. By contrast, withdrawal reflexes in the biceps posterior-semitendinosus muscles of the thigh could only be weakly inhibited by conditioning skin stimulation. 3. Powerful inhibition of withdrawal reflexes in single lower leg muscles was elicited from the ipsilateral hindpaw plantar area, which would move towards the stimulation on contraction in the respective muscle. In addition, weak nociceptive inhibition was evoked from the corresponding skin areas on the contralateral hindlimb and, in some muscles, the tail. 4. The ipsilateral inhibitory and excitatory receptive fields of the withdrawal reflexes in single muscles overlapped somewhat. On stimulation of these transitional areas the reflex responses were preceded by a short-lasting inhibition. 5. Graded mechanical and thermal stimulation demonstrated prominent inhibitors effects from nociceptive receptors. Weak inhibitory effects were elicited by innocuous mechanical stimulation, suggesting a weak contribution from low threshold mechanoreceptors. Latency measurements indicated an inhibitory input from both myelinated and unmyelinated fibres. 6. In conclusion, the withdrawal reflex pathways receive a powerful nociceptive inhibitory input through spinal pathways. The movement-related organization of this input suggests that it serves to prevent inappropriate withdrawal reflexes. Images Figure 3 Figure 4 Figure 5

Weng, H R; Schouenborg, J



Pneumatic Registration of Vestibulospinal Reflexes  

Microsoft Academic Search

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

M. Spector



Stretch reflexes in human masseter.  

PubMed Central

The reflex response to stretch in most contracting human muscles includes both a short-latency, probably monosynaptic, excitatory component, and a longer-latency, polysynaptic excitation. However, it has been claimed that stretch of the jaw-closing muscles evokes only the short-latency response in masseter. This question was re-examined, using controlled stretches of varied rates and durations. Very brief, rapid stretches analogous to the stimuli used to investigate the 'jaw-jerk' reflex in earlier studies evoked a prominent excitatory peak in the electromyogram at monosynaptic latency excitation, but little or no longer-latency excitation. This response could be produced even by stimuli that were barely detectable by the subject. However, this prominent electrical response did not produce a measurable increase in biting force. In contrast, slower stretches evoked both a short- and a longer-latency excitatory response in the surface electromyogram, as in most limb muscles. It is shown that the absence of a long-latency excitatory response in earlier studies can be explained by the powerful reflex disfacilitation of the motoneurones that occurred at the end of the brief stretches used. Depending on the duration of the stretch, this disfacilitation is often sufficient to mask or abolish the long-latency reflex. The reflex response to stretches was not markedly affected by blocking the activation of mechanoreceptors around the teeth with local anaesthetic, indicating that receptors around the teeth cannot be playing more than a minor role in the response. The stretch-induced increase in force became greater as the velocity of the stretch decreased.

Poliakov, A V; Miles, T S



Reflex anuria following acute cardiac event  

PubMed Central

Background Reflex anuria is an uncommon cause for acute renal failure, which occurs almost always after manipulation or irritation to kidneys, ureter, bladder or other pelvic organs. Case presentation Here we describe a case of acute renal failure due to reflex anuria following acute cardiac event. This patient had background history of urolithiasis. In the absence of other pre renal, renal or post- renal causes for acute kidney injury, we believe reflex anuria is the causative entity for acute renal failure in our patient. Conclusion Acute renal failure due to reflex anuria is related to a reflex mechanism involving arteriolar vasoconstriction and urethral spasm. Patients with reflex anuria can be successfully managed with medical or surgical interventions. Our case suggests that reflex anuria should be considered as one of the differential diagnosis of acute renal failure following acute cardiac event, especially in patients with background urological problem.



Presynaptic inhibition of the monosynaptic reflex following the stimulation of nerves to extensor muscles of the ankle  

Microsoft Academic Search

1.Electrical stimulation of extensor nerves of the ankle has been used to investigate the presynaptic inhibition in a synergic monosynaptic reflex arc.2.Depression of monosynaptic reflex response as well as increase in excitability of Ia afferent terminals in the MG (medial gastrocnemius) reflex arc is found following the conditioning stimulation of LGS (lateral gastrocnemius-soleus) nerve at Group I strength.3.Excitability increase of

M. Decandia; L. Provini; H. Tábo?íková



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



Changes in spinal reflex excitability associated with motor sequence learning.  


There is ample evidence that motor sequence learning is mediated by changes in brain activity. Yet the question of whether this form of learning elicits changes detectable at the spinal cord level has not been addressed. To date, studies in humans have revealed that spinal reflex activity may be altered during the acquisition of various motor skills, but a link between motor sequence learning and changes in spinal excitability has not been demonstrated. To address this issue, we studied the modulation of H-reflex amplitude evoked in the flexor carpi radialis muscle of 14 healthy individuals between blocks of movements that involved the implicit acquisition of a sequence versus other movements that did not require learning. Each participant performed the task in three conditions: "sequence"-externally triggered, repeating and sequential movements, "random"-similar movements, but performed in an arbitrary order, and "simple"- involving alternating movements in a left-right or up-down direction only. When controlling for background muscular activity, H-reflex amplitude was significantly more reduced in the sequence (43.8 +/- 1.47%. mean +/- SE) compared with the random (38.2 +/- 1.60%) and simple (31.5 +/- 1.82%) conditions, while the M-response was not different across conditions. Furthermore, H-reflex changes were observed from the beginning of the learning process up to when subjects reached asymptotic performance on the motor task. Changes also persisted for >60 s after motor activity ceased. Such findings suggest that the excitability in some spinal reflex circuits is altered during the implicit learning process of a new motor sequence. PMID:20237314

Lungu, Ovidiu; Frigon, Alain; Piché, Mathieu; Rainville, Pierre; Rossignol, Serge; Doyon, Julien



Reflex control of dynamic muscle stiffness in a slow crustacean muscle.  


The properties of a stretch reflex in the ventral superficial muscle of the hermit crab abdomen were studied in an isolated abdominal preparation to determine how the reflex affects the mechanical properties of the muscle and whether the reflex is controlling length, force, or stiffness. The reflex was elicited by stretch of hypodermal mechanoreceptors in the cuticle and resulted in the activation of excitor motoneurons to both circular and longitudinal layers of the muscle, thus stiffening the abdomen. The medial motoneuron of the longitudinal layer of the right fourth segment was selected for detailed analysis. It was tonically active and responded to stretch with a phasic burst having a latency of 100 ms. Reflex muscle tension began to increase at 130 ms and reached a peak at 300 ms. Reflex-burst frequency increased slightly with stretch amplitude. Peak force was an approximately linear function of stretch amplitude. No tonic component to the reflex was found in the medial motoneuron, in the central motoneuron (the smallest excitor to the muscle), or in the medial motoneuron studied in intact animals. The reflex-burst frequency was a function of stretch velocity, increasing between two and one-half to four times for a 10-fold increase in stretch velocity. Peak force was essentially independent of stretch velocity over this range. The reflex-burst frequency was not a function of the initial length of the muscle on the ascending limb of the length-tension relation. Active peak force (between two and three times passive peak force) was relatively constant over this range. The dynamic active stiffness (the resistance to stretch of the muscle when the nervous system was intact) was separated into two components. One component is that due to the tonic frequency of the motoneurons, the other to the reflex burst. The reflex component makes up a substantial part of the total active stiffness. Dynamic active stiffness is relatively constant under the conditions of these experiments and, when normalized, is similar to that observed in mammalian myotatic reflexes. This constancy, however, cannot be due to negative feedback control of stiffness, as in mammals. It is suggested that constant reflex stiffness arises from the combination of the low-pass filter characteristics of the muscle and the high-pass filter characteristics of the reflex over a restricted range of velocities.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:4031994

Chapple, W D



Effects of heterotopic- and segmental counter-stimulation on the nociceptive withdrawal reflex in humans.  


A nociceptive withdrawal reflex in 12 human volunteers was elicited by painful electrical stimulation applied to the cutaneous innervation area of the sural nerve. The evoked electromyographic reflex activities were recorded with surface electrodes placed on the short head of the biceps femoris muscle ipsi-lateral to sural nerve stimulation, before, during and after conditioning stimuli. The nociceptive withdrawal reflex was conditioned by nociceptive and non-nociceptive, heterotopic and segmental counter-stimulation. Heterotopic nociceptive counter-stimulation and segmental nociceptive counter-stimulation were induced by ice water applied to the contra-lateral hand and foot, respectively. Heterotopic nociceptive counter-stimulation produced a significant inhibition of the nociceptive withdrawal reflex and the associated pains rating to sural nerve stimulation. Segmental nociceptive counter-stimulation inhibited the pain rating and tended to inhibit the nociceptive withdrawal reflex. There was no obvious correlation between visual analogue scale (VAS) and the nociceptive withdrawal reflex elicited by sural nerve stimulation neither in the group nor in the individual subject. This suggests that the nociceptive withdrawal reflex cannot always be used as a quantitative measure of pain. PMID:11472308

Terkelsen, A J; Andersen, O K; Hansen, P O; Jensen, T S



[Reflexivity: a critical issue in qualitative research].  


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



Effects of muscle history on the stretch reflex in cat and man.  

PubMed Central

1. This is a report of experiments on cat and man which demonstrate effects of a muscle's previous history of contraction and length changes on the size of the stretch reflex. 2. In adult human subjects the size of the tendon jerk was measured in ankle extensor muscles by tapping the Achilles tendon. Muscle conditioning consisted of a maximum voluntary contraction with the foot dorsiflexed or plantarflexed by 30 deg from the test position, after which the subject was asked to relax while the foot was held still for several seconds before being returned to the test position and a tendon tap given. After a contraction of the lengthened muscle the tendon jerk was smaller than after a contraction of the shortened muscle. 3. The experiment was then repeated, but instead of a tendon jerk an H (Hoffmann) reflex was elicited by transcutaneous electrical stimulation of the tibial nerve in the popliteal fossa. The reflex after a conditioning contraction of the lengthened muscle was larger than after a contraction of the shortened muscle. In other words muscle conditioning produced opposite effects on the tendon jerk and H reflex. 4. These findings were confirmed in cats anaesthetized with chloralose. After a conditioning contraction of triceps surae at a length 5 mm longer than the test length (hold-long) a quick tendon stretch produced a smaller reflex response than following a conditioning contraction with the muscle 5 mm shorter than the test length (hold-short). The reverse trend was seen with a reflex elicited by direct electrical stimulation of the muscle nerve, which stimulates the H reflex. 5. One consequence of a conditioning contraction is that it leads to an alteration of the level of resting discharge of muscle spindles. We propose that the larger tendon jerk after a contraction of the shortened muscle is the result of changes in stretch sensitivity of muscle spindles. The reverse effect on the H reflex we attribute to a rise in the level of resting discharge of muscle spindles, which, we propose, leads to reflex inhibition of motoneurones. 6. We support this conclusion with evidence from an experiment in which the size of the conditioning step was systematically altered. Even quite small hold-short conditioning steps led to depression of the H reflex in man and the monosynaptic reflex in cats. Recordings from single afferents showed that such small steps were also accompanied by a detectable rise in spindle resting discharge.(ABSTRACT TRUNCATED AT 400 WORDS) Images Fig. 5

Gregory, J E; Mark, R F; Morgan, D L; Patak, A; Polus, B; Proske, U



Algebras whose projective modules are reflexive  

Microsoft Academic Search

The algebras of the title are investigated. They are shown to include l-hereditary algebras, monomial algebras whose indecomposable projective representations are reflexive, and certain binomial algebras.

K. R. Fuller; W. K. Nicholson; J. F. Watters



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

PubMed Central

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

Hultborn, H; Pierrot-Deseilligny, E



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

Microsoft Academic Search

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

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



Fragments of galanin message-associated peptide (GMAP) modulate the spinal flexor reflex in rat  

Microsoft Academic Search

We have previously reported that galanin message-associated peptide (GMAP), a fragment of galanin precursor protein, is present in dorsal root ganglion cells and upon intrathecal (i.t.) administration influences the spinal nociceptive flexor reflex in a complex manner in the rat. GMAP elicited a moderate facilitation of the flexor reflex, but when administered prior to conditioning stimulation of C-afferents, it dose

Xiao-Jun Xu; Siv Andell; Tamás Bartfai; Zsuzsanna Wiesenfeld-Hallin



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


The Reflex Mechanism of the Insect Leg  

Microsoft Academic Search

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

J. W. S. Pringle



Possible Relationships between Orienting and Diving Reflexes  

Microsoft Academic Search

THE diving reflex has been studied extensively in aquatic organisms that breathe air and submerge to obtain food or to escape from predators such as ducks, seals and alligators1. This reflex seems to have two phases: an initial phase which may be mediated by the vagus and trigeminal nerves2, and a later one which follows prolonged holding of the breath

David A. Goodman; Norman M. Weinberger



The grasp and other primitive reflexes  

PubMed Central

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

Schott, J; Rossor, M



Photorealistic models for pupil light reflex and iridal pattern deformation  

Microsoft Academic Search

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

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



Circular vection during voluntary suppression of optokinetic reflex  

Microsoft Academic Search

Optokinetic circular vection (CV) was investigated in 12 subjects using an optokinetic pattern rotating at 15°\\/s, 30°\\/s, or\\u000a 60°\\/s, and four viewing conditions: FOL, subjects attentively followed details of pattern; STA, subjects stared at the pattern;\\u000a SUP, subjects suppressed their optokinetic reflex (OKR) voluntarily (this was facilitated by a white, featureless band at\\u000a eye level which separated the pattern in

Wolfgang Becker; Sabine Raab; Reinhart Jürgens



Achilles tendon reflex measuring system  

NASA Astrophysics Data System (ADS)

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

Szebeszczyk, Janina; Straszecka, Joanna



Independent segmental inhibitory modulation of synaptic efficacy of the soleus H-reflex.  


Synaptic efficacy associated with muscle spindle feedback is partly regulated via depression at the Ia-motorneuron synapse through paired reflex depression (PRD) and presynaptic inhibition (PI). The purpose of this study was to examine PRD and PI of the soleus H-reflex at rest and with a background voluntary muscle contraction. The experiment was conducted on 10 healthy males with no history of neurological deficits. Soleus H-reflex and M-wave curves were elicited in three conditions: unconditioned, PRD (two consecutive H-reflexes with 100?ms interval), and PI (1.2?×?MT to tibialis anterior 100?ms prior to soleus H-reflex). Each condition was tested at rest and with a 10% soleus contraction. PRD and PI both produced a pronounced inhibition to the soleus motor pool at rest, with a significant difference observed between threshold values (78.9, 89.3, and 90.4% for unconditioned, PRD, and PI reflexes, respectively). During the voluntary contraction the threshold for both inhibitory mechanisms was significantly reduced, and were not different from the unconditioned H-reflex (74.5, 78.9, and 77.0% for unconditioned, PRD, and PI reflexes, respectively). The slope of PI and the PI Hmax/Mmax ratio were significantly altered during contraction whereas no differences were observed for PRD. The results suggest these inhibitory mechanisms depend on the interaction between background voluntary activation and stimulus intensity. This behavior of these inhibitory mechanisms underscores the specificity of spinal circuitry in the control of motor behaviors. PMID:23682774

Robertson, Christopher T; Kitano, Koichi; Koceja, David M; Riley, Zachary A



Reflexive fighting in response to aversive stimulation1  

PubMed Central

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

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



Blink reflexes and the state of arousal.  

PubMed Central

Blink reflexes were studied in 40 subjects at rest and during the performance of a task. The early reflex (R1) showed an increase of amplitude of action potential during the task, the late reflex (R2) did not. The latency of R1 did not change within the 45 minutes test period; R2 showed an increase of latency during task. R1 showed a systematic decrease in amplitude within rest and task periods, presumably because of habituation. R2 amplitudes decreased throughout the whole experiment, independent of task or rest.

Boelhouwer, A J; Brunia, C H



Discursive Reflexivity in the Ethnography of Communication: Cultural Discourse Analysis  

Microsoft Academic Search

This article is a creative reconstruction of reflexivity as it operates for some practitioners of the ethnography of communication. Our central concern is conceptualized as “discursive reflexivity”; with that concept, we foreground communication both as primary data and as our primary theoretical concern. As a result, we treat reflexivity as a process of metacommunication, that is, as a reflexive process

Donal Carbaugh; Elena V. Nuciforo; Elizabeth Molina-Markham; Brion van Over



Short-term locomotor adaptation to a robotic ankle exoskeleton does not alter soleus Hoffmann reflex amplitude  

PubMed Central

Background To improve design of robotic lower limb exoskeletons for gait rehabilitation, it is critical to identify neural mechanisms that govern locomotor adaptation to robotic assistance. Previously, we demonstrated soleus muscle recruitment decreased by ~35% when walking with a pneumatically-powered ankle exoskeleton providing plantar flexor torque under soleus proportional myoelectric control. Since a substantial portion of soleus activation during walking results from the stretch reflex, increased reflex inhibition is one potential mechanism for reducing soleus recruitment when walking with exoskeleton assistance. This is clinically relevant because many neurologically impaired populations have hyperactive stretch reflexes and training to reduce the reflexes could lead to substantial improvements in their motor ability. The purpose of this study was to quantify soleus Hoffmann (H-) reflex responses during powered versus unpowered walking. Methods We tested soleus H-reflex responses in neurologically intact subjects (n=8) that had trained walking with the soleus controlled robotic ankle exoskeleton. Soleus H-reflex was tested at the mid and late stance while subjects walked with the exoskeleton on the treadmill at 1.25 m/s, first without power (first unpowered), then with power (powered), and finally without power again (second unpowered). We also collected joint kinematics and electromyography. Results When the robotic plantar flexor torque was provided, subjects walked with lower soleus electromyographic (EMG) activation (27-48%) and had concomitant reductions in H-reflex amplitude (12-24%) compared to the first unpowered condition. The H-reflex amplitude in proportion to the background soleus EMG during powered walking was not significantly different from the two unpowered conditions. Conclusion These findings suggest that the nervous system does not inhibit the soleus H-reflex in response to short-term adaption to exoskeleton assistance. Future studies should determine if the findings also apply to long-term adaption to the exoskeleton.



The effects of intrathecal galanin message-associated peptide (GMAP) on the flexor reflex in rats.  


We have examined the effects of intrathecal (i.t.) galanin message-associated peptide (GMAP), the C-terminal flanking peptide in the galanin (GAL) precursor protein, which is produced in equimolar quantities with galanin and which is upregulated upon axotomy, on the spinal nociceptive flexor reflex in decerebrate, spinalized, unanesthetized rats. I.t. GMAP elicited a moderate facilitation of the flexor reflex. No depression of baseline flexor reflex was observed with any dose of GMAP. The facilitation of the flexor reflex induced by conditioning stimulation (CS) of cutaneous C-afferents was dose-dependently blocked by GMAP. The reflex facilitatory effect of exogenously applied substance P (SP), one of the endogenous modulators of reflex hyperexicitability following C-fiber CS, was only blocked by GMAP at a relatively high dose. I.t. GMAP did not antagonize the reflex facilitatory effect of vasoactive intestinal peptide and did not potentiate the reflex depressive effect of i.t. morphine or clonidine. Finally, 1 micrograms i.t. GMAP did not influence spinal cord blood flow whereas 10 micrograms GMAP induced a transient decrease in spinal cord blood flow in some experiments. The ability of GMAP to block the increase in spinal cord excitability following repetitive C-fiber stimulation may be through a presynaptic action. Although some of the effects of GMAP were similar to galanin, distinct differences were found, particularly in interaction with other excitatory and inhibitory agents. It is possible that GMAP exerts its action in the spinal cord through its own specific receptor. GMAP may act similarly to GAL in some, but not all pharmacological functions.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8570856

Xu, X J; Andell, S; Hao, J X; Wiesenfeld-Hallin, Z; Bartfai, T



Dolphin Brain Structure, Reflexes and Echolocation Behavior.  

National Technical Information Service (NTIS)

Structural organization of the limbic cortex of the dolphin brain; Role of underwater exhalations and emergence reflexes in cetaceans; Echolocation discrimination of geometric figures in the dolphin delphinius delphis.

V. S. Kesarev A. G. Tomilin D. A. Morozov V. S. Gurevich



Primitive reflexes and early motor development.  


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

Bartlett, D




Microsoft Academic Search

Module theoretic methods are employed to obtain simple proofs of extensions of two theorems of E. A. Azo regarding the reflexivity of direct sums of copies of an algebra of operators on a nite dimensional Hilbert space.



A case of linear morphoea mistaken for reflex sympathetic dystrophy.  


Morphoea, or localised scleroderma, is a disease entity with poorly understood pathogenesis. Early diagnosis of the condition is crucial in order to prevent permanent morbidity. However, initial presentations of morphoea can be nonspecific and easily mistaken for other conditions, resulting in late treatment and permanent disability. We report a case of linear morphoea in a 22-year-old man who was initially diagnosed with reflex sympathetic dystrophy. By the time the diagnosis of morphoea was confirmed, the patient had already developed contractures. PMID:23546034

Thng, Steven Tien Guan; Wong, Keryi



Reflex responses of masseter muscles to sound.  


Acoustic stimuli can evoke reflex EMG responses (acoustic jaw reflex) in the masseter muscle. Although these were previously ascribed to activation of cochlear receptors, high intensity sound can also activate vestibular receptors. Since anatomical and physiological studies, both in animals and humans, have shown that masseter muscles are a target for vestibular inputs we have recently reassessed the vestibular contribution to masseter reflexes. We found that high intensity sound evokes two bilateral and symmetrical short-latency responses in active unrectified masseter EMG of healthy subjects: a high threshold, early p11/n15 wave and a lower threshold, later p16/n21 wave. Both of these reflexes are inhibitory but differ in their threshold, latency and appearance in the rectified EMG average. Experiments in healthy subjects and in patients with selective lesions showed that vestibular receptors were responsible for the p11/n15 wave (vestibulo-masseteric reflex) whereas cochlear receptors were responsible for the p16/n21 wave (acoustic masseteric reflex). The possible functional significance of the double vestibular control over masseter muscles is discussed. PMID:20447862

Deriu, Franca; Giaconi, Elena; Rothwell, John C; Tolu, Eusebio



[Acupuncture and reflex sympathetic dystrophy].  


The term "reflex sympathetic dystrophy" (RSD) is used for various syndromes, e.g. posttraumatic edema, shoulder-hand syndrome, algodystrophy and causalgia. The clinical symptoms of RSD are characterized by a triad of autonomic, sensory and motor disturbances, which usually develop in the distal region of an affected extremity. The main symptoms are swelling, a side difference in skin temperature (autonomic symptoms), reduced active movements and muscular strength (motor symptoms) and spontaneous, deep, diffuse pain with an orthostatic component (sensory system). As soon as possible the treatment of RSD should include sympatholytic strategies and obligatory physical therapy. Acupuncture has also been reported to reduce sympathetic activity. The analgesic effect of acupuncture is well known, and therefore from an at least theoretical point of view, it should make sense to use acupuncture in the treatment of RSD. To date, however, no prospective, randomized, controlled, clinical long-term studies have been done. One short-term study showed promising results, but did not reach statistical significance. In that study acupuncture treatment seemed to alleviate the major symptoms of RSD. Since acupuncture rarely has side effects, its role as an additional option in the treatment of RSD should be further investigated. PMID:12799835

Spacek, A; Kress, H G



Reflex ring laser amplifier system  


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.



Relating plastic changes of short latency human soleus stretch reflex to changes in task performance induced by training.  


Recent findings in the field of neurophysiology showed that operant conditioning on the human H-Reflex is possible. This leads to many possible clinical applications as well as possible sophisticated training methods for athletes. Although stretch reflexes have been subject to extensive literature, knowledge about the influence of short latency stretch reflexes on task performance is lacking. Within this study an ankle control task was designed where perturbations in the magnitude of functional relevance were applied. Results analyzing angle over time after perturbation confirm previous findings which used to analyze the EMG and force response to ankle perturbations. Further it was found that after training the response to perturbations shifted from initially containing latencies which indicate conscious support by transcortical pathways to latencies which could only origin from unconscious stretch reflex responses. The trend of the short latency response to shift towards the long latency response and to diminish, while pre-defined performance criteria improved, denote a functional relevance of the short latency stretch reflex to task performance. Whereas short latency reflexes have any importance at all or if improvements emerge only out of enhancements in the long latency response future work making use of operant conditioning on the short latency H-Reflex will have to unravel. PMID:23366715

Kundert, Robinson; Yagi, Tohru



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

Microsoft Academic Search

Distraction from pain reduces pain perception, and imaging studies have suggested that this may at least partially be mediated by activation of descending pain inhibitory systems. Here, we used the nociceptive flexor reflex (RIII reflex) to directly quantify the effects of different distraction strategies on basal spinal nociception and its temporal summation. Twenty-seven healthy subjects participated in 3 distraction tasks

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



The bulbocavernosus reflex. A single motor neuron study.  


Reflex latency variability was established for single motor neuron discharges in the bulbocavernosus reflex, as elicited by electrical stimuli to the dorsal penile nerve and recorded by a single fibre EMG electrode in the bulbocavernosus muscle. Whereas many reflex responses had a rather large latency variability of above 1000 microseconds (expressed as SD of mean latency) there was a group of motor neurons with a variability of around 500 microseconds. Single motor neuron reflex responses with shorter latencies tended to show less variability. No habituation of single motor neuron reflex discharges was observed on prolonged regular repetitive stimulation. Both absence of habituation and the relatively low latency variability of bulbocavernosus reflex responses for single motor neurons suggest similarities between this reflex and the first component of the blink reflex; we postulate that the shortest bulbocavernosus reflex pathway is oligosynaptic. PMID:2364270

Vodusek, D B; Janko, M



Effects of peripheral inputs from hindlimb on the monosynaptic reflex of motoneurons innervating tail muscles.  


The effects of group II muscle (PBSt, GS) and cutaneous afferent (Sur, SPc, Tib) inputs from the hindlimb on the monosynaptic reflexes of motoneurons innervating tail muscles were studied in lower spinalized cats. Stimulation of the cutaneous nerves at the conditioning-test stimulus interval of about 10-20 ms facilitated and inhibited the monosynaptic reflexes of ipsilateral and contralateral tail muscles, respectively. The effects of the muscle nerve stimulation were not so prominent as those elicited by cutaneous nerve stimulation. The monosynaptic reflex was also inhibited by muscle nerve stimulation at 10-50 ms intervals. The effects of conditioning stimulation of the hindlimb peripheral nerves at short intervals were depressed or blocked by section of the ipsilateral lateral funiculus at S1 spinal segment. These findings show that the neuronal pathway from hindlimb afferents to tail muscle motoneurons passed the lateral funiculus of the spinal cord and modulates the motoneuronal activity of tail muscles. PMID:1789716

Wada, N



Fragments of galanin message-associated peptide (GMAP) modulate the spinal flexor reflex in rat.  


We have previously reported that galanin message-associated peptide (GMAP), a fragment of galanin precursor protein, is present in dorsal root ganglion cells and upon intrathecal (i.t.) administration influences the spinal nociceptive flexor reflex in a complex manner in the rat. GMAP elicited a moderate facilitation of the flexor reflex, but when administered prior to conditioning stimulation of C-afferents, it dose dependently blocked spinal cord hyperexcitability. The present study examined the effects of four fragments of GMAP-(1-60), GMAP-(1-12), GMAP-(10-24), GMAP-(25-44) and GMAP-(37-60), on the flexor reflex and compared them with the effects of the complete peptide sequence. All four GMAP fragments facilitated the flexor reflex. However, this effect was dose-dependent only for GMAP-(1-12) and the effect of GMAP-(1-12) was stronger than GMAP-(1-60). In contrast, only GMAP-(25-44) dose dependently blocked the facilitation of the flexor reflex induced by the C-fiber conditioning stimulation. The potency of the blocking effect of GMAP-(25-44) was one order of magnitude lower than that of GMAP-(1-60). The results indicated that two fragments of GMAP are pharmacologically active and produce effects which are similar to the full sequence. It is possible that the complex effect of GMAP may be mediated by different subtypes of GMAP receptors which recognize different portions of the GMAP sequence. PMID:9016918

Xu, X J; Andell, S; Bartfai, T; Wiesenfeld-Hallin, Z



Impaired Reflex Vasoconstriction in Chronically Hypoxemic Patients  

PubMed Central

Acute hypoxia impairs vasoconstrictor responses in normal men. The present study was done to determine whether reflex vasoconstriction is impaired in chronically hypoxemic patients and whether correction of hypoxemia in these patients improves their cardiovascular reflexes. In eight chronically hypoxemic patients, arterial PO2 was increased from an average of 45 mm Hg while breathing room air to 161 mm Hg while breathing 40-100% oxygen, with minimal changes in arterial PCO2 or pH. Correction of hypoxemia did not cause changes in resting arterial pressure or in forearm vascular resistance, but it caused a small increase in resting heart rate. Reflex responses to lower body negative pressure, which causes pooling of blood in the lower part of the body, were observed. When the patients were hypoxemic, lower body negative pressure caused a fall in arterial pressure, slight constriction of forearm vessels, and a small increase in heart rate. When hypoxemia was corrected, the same intervention caused marked vasoconstriction and a greater increase in heart rate, and there was no decrease in arterial pressure. The results indicate that reflex vasoconstrictor responses are depressed in chronic hypoxemia, indicating that adaptive mechanisms which occur in chronic hypoxemia do not include preservation of sympathetic reflexes. Images

Heistad, Donald D.; Abboud, Francois M.; Mark, Allyn L.; Schmid, Phillip G.



Using ESO Reflex with Web Services  

NASA Astrophysics Data System (ADS)

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

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



Munchausen's syndrome simulating reflex sympathetic dystrophy.  

PubMed Central

A 15 year old girl who had pain, oedema of her left hand, and fever of four months' duration is described. Marked demineralisation of her hand was shown by radiography, and increased articular uptake by technetium-99m bone scan. All these changes were indistinguishable from reflex sympathetic dystrophy. After two admissions to hospital and multiple explorations we discovered that she had induced her symptoms herself and a diagnosis of Munchausen's syndrome was made. As far as we know this presentation has not been previously reported and might help to explain the physiopathology of some signs of reflex sympathetic dystrophy. Images

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



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


Our previous work showed a beneficial therapeutic effect on blepharospasm using slow repetitive transcranial magnetic stimulation, which produces a long-term depression (LTD)-like effect. High-frequency supraorbital electrical stimulation, asynchronous with the R2 component of the blink reflex, can also induce LTD-like effects on the blink reflex circuit in healthy subjects. Patients with blepharospasm have reduced inhibition of their blink recovery curves; therefore, a LTD-like intervention might normalize the blink reflex recovery (BRR) and have a favorable therapeutic effect. 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 nine stimuli, 400 Hz, 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 BRR. Stimulation "before" and "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 noted only in the before condition. Clinical symptoms differed in the three baseline conditions (resting, reading, and talking). Stimulation before R2 increased inhibition in trigeminal blink reflex circuits in blepharospasm toward normal values and produced subjective, but not objective, improvement. Inhibition of the blink reflex pathway by itself appeared to be insufficient for a useful therapeutic effect. PMID:23401198

Kranz, Gottfried; Shamim, Ejaz A; Lin, Peter T; Kranz, George S; Hallett, Mark



Monitoring of head injury by myotatic reflex evaluation  

Microsoft Academic Search

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.METHODSThe phasic stretch reflex of biceps brachii was elicited by a servo-positioned

J Alastair Cozens; Simon Miller; Iain R Chambers; A David Mendelow



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


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



Jaw, blink and corneal reflex latencies in multiple sclerosis  

Microsoft Academic Search

Jaw, blink and corneal reflexes, which all involve the trigeminal system, were recorded in 54 patients with multiple sclerosis; thirty-seven of these patients were classified as having definite multiple sclerosis and 17 as indefinite multiple sclerosis, according to Schumacher's criteria. The jaw reflex was abnormal less frequently than either of the other two reflexes, but in four cases it was

E A Sanders; B W Ongerboer de Visser; E C Barendswaard; R J Arts



The Acoustic Reflex in Diagnostic Audiology: From Metz to Present  

Microsoft Academic Search

In 1946, Metz described what was probably the first practical impedance bridge for measurement of the acoustic reflex. Over the next four decades, diagnostic use of the acoustic reflex progressed in parallel with instrumentation refinements. Today, acoustic reflex threshold and decay testing are a routine com- ponent of the diagnostic audiology test battery. Recent advances in the measurement of suprathreshold

Brad A. Stach



Neural basis of environmental regulation of the Aplysia siphon-withdrawal reflex  

Microsoft Academic Search

All organisms must cope with environmental change, adjusting their behavior to match the current conditions of the environment. This research project explores how a simpler nervous system accomplishes this task. Specifically, it examines how Aplysia californica adjust the siphon-withdrawal reflex (SWR) to cope with exposure to water turbulence, an environmental change Aplysia often encounter in the wild. ^ Behavioral experiments

Robert J Calin-Jageman



Reflex bradycardia in out-patient surgery done under local anesthesia  

Microsoft Academic Search

Reflex bradycardia is an abnormal reaction to certain stimuli causing a sustained drop in pulse rate; it responds promptly to the administration of atropine. Arrhythmia, fall in blood pressure and oxygen saturation may also occur. If not treated promptly, the condition may be fatal. From 432 consecutive plastic surgical patients operated under local anesthesia at a surgical day care clinic,

P. J. Hurwitz; M. Ogilvie



The reflex effect of cardiovascular drugs arising from the venous receptors of the frog  

Microsoft Academic Search

The reflex effect on the heart and respiration of caffeine, strophantin, adrenalin and nitroglycerin was studied in conditions of perfusion of the humorally isolated femoral vein or of the whole frog's extremity. The impulse activity of the venous receptors was also registered.

P. F. Konovalov; G. N. Sorokhtin



Changes of Reflex, Non-reflex and Torque Generation Properties of Spastic Ankle Plantar Flexors Induced by Intelligent Stretching  

Microsoft Academic Search

Spasticity, contracture, and muscle weakness are major sources of disability in stroke. Changes of torque-generating capacity as well as reflex and non-reflex properties of ankle plantar flexors induced by strenuous stretching in chronic hemiplegia were investigated. Twelve subjects with a unilateral stroke and 10 healthy controls underwent 30 minutes of strenuous intelligent stretching treatment. Reflex and non-reflex components of spastic

S. G. Chung; Z. Bai; W. Z. Rymer; L. Q. Zhang



The effect of startle reflex habituation on cardiac defense: interference between two protective reflexes.  


The present study investigated the relationship between blink startle and cardiac defense, two protective reflexes that are said to be elicited by the transient and the sustained components, respectively, of high intensity stimuli. Three groups of participants were presented with three intense long lasting noise stimuli (500ms) after habituation training with 12 brief (50ms) high intensity noise bursts (High group), low intensity noise bursts (Low group) or high intensity visual stimuli (Light group). The transition from habituation to defense stimuli resulted in increased blink startles in groups Low and Light, but not in group High. A cardiac defense reflex, characterised by a short and long delayed increase in heart rate, was observed in group Light, but not in groups Low and High. This pattern of results indicates that habituation to startle eliciting stimuli will impair defense reflexes elicited on subsequent test trials and suggests some interrelation between the two reflex systems. PMID:18406485

Fernández, María Carmen; Vila, Jaime; Lipp, Ottmar V; Purkis, Helena M



Differentiation between protective reflexes: cardiac defense and startle.  


Rise time and duration are two parametric characteristics of the eliciting stimulus frequently used to differentiate among psychophysiological reflexes. The present research varied the duration (study 1) and rise time (study 2) of an intense acoustic stimulus to dissociate cardiac defense and cardiac startle using the eyeblink response as the external criterion of startle. In each study, 100 participants were presented with five white noise stimuli of 105 dB under one of five duration (50, 100, 250, 500, and 1000 ms) or rise time (0, 24, 48, 96, and 240 ms) conditions. Cardiac defense was affected by stimulus duration, present only in the 500- and 1000-ms conditions, but not by stimulus rise time, present in all rise time conditions. Rise time affected blink startle, but did not selectively alter the short latency accelerative component of the heart rate response, thus questioning whether it reflects startle. PMID:16364069

Ramírez, Isabel; Sánchez, María B; Fernández, María Carmen; Lipp, Ottmar V; Vila, Jaime



Blink Reflex Abnormalities in Chronic Alcoholics  

Microsoft Academic Search

Purpose: The aim of the present study was to evaluate the efficacy of blink reflex as a method for obtaining early diagnosis of cranial nerve involvement in alcoholic patients. Materials and Methods: The study was conducted on 30 male alcoholics with a mean age of 43 years. They had histories of alcohol abuse for at least 6 years (mean: 25).



Anorectal Tightening Reflex: Role in Fecal Incontinence  

Microsoft Academic Search

The present study describes the clinical significance of the anorectal tightening reflex (ATR) in normal and incontinent subjects. It was examined in 16 healthy volunteers and 11 subjects incontinent to flatus and fluid stools; 5 of the latter had in addition fecal soiling. The rectum was distended by a condom inflated with carbon dioxide, while the rectal and rectal neck

Ahmed Shafik



Reflexivity of spaces of weakly summable sequences  

Microsoft Academic Search

We deal with the space of -summable sequences from a locally convex space E, where is a metrizable perfect sequence space. We give a characterization of the reflexivity of ( E) in terms of that of and E and the AK property. In particular, we prove that if is an echelon sequence space and E is a Fr´ echet space

L. Oubbi; M. A. Ould Sidaty



Grounded theory research: literature reviewing and reflexivity  

Microsoft Academic Search

Title. Grounded theory research: literature reviewing and reflexivity Aim. This paper is a report of a discussion of the arguments surrounding the role of the initial literature review in grounded theory. Background. Researchers new to grounded theory may find themselves confused about the literature review, something we ourselves experienced, pointing to the need for clarity about use of the literature

Gerry McGhee; Glenn R. Marland; Jacqueline Atkinson; RMN RNT




Microsoft Academic Search

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

Anna Rita Addessi


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



Cortical neuromagnetic activity associated with cutaneomuscular reflex.  


Cortical activity related to the late component of the cutanomuscular reflex was studied by measuring somatosensory evoked magnetic fields (SEFs) during isometric contraction of the reflex-induced muscle. After electrical stimulation to the index finger with intensity of three times of the perception threshold, three peaks of the cortical activity were detected within the somato-sensory area contralaterally to the stimulation site. Three dimentional location and the amplitude of the equivalent current dipoles for each peak were compared to that of observed SEF without muscle contraction. Significantly increased third component of SEFs (the latency of about 50 ms) always preceeded ca 20 ms against the peak of the late component of the cutaneomusucular reflex observed in the first dorsal interosseous (1DI) muscle. The conduction delay from the primary somatomotor cortex to the 1DI was determined as also ca 20 ms according to the result of the transcranial magnetic stimulation. We conclude from these evidences that all or part of the ingredient of the third component of SEFs may contribute to inducement of the late excitatory component of the cutaneomuscular reflex. PMID:15061401

Masakado, Y; Ushiba, J; Tomita, Y; Chino, N



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



An architecture for reflexive autonomous vehicle control  

Microsoft Academic Search

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

David W. Payton



Self hypnotherapeutic treatment of habitual reflex vomiting.  

PubMed Central

A 9 year old boy with intractable postprandial reflex vomiting was taught a self hypnotherapy technique incorporating relaxation exercises, mental imagery, and suggestions of symptom relief. The sequence was recorded on a personal stereo cassette tape. Vomiting was completely eliminated within four weeks. At 12 month review vomiting had not recurred.

Sokel, B S; Devane, S P; Bentovim, A; Milla, P J



Computational Modeling of the Bremsstrahlung Reflex Triode  

NASA Astrophysics Data System (ADS)

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

Stark, Robert



Photic sneeze reflex in nephropathic cystinosis  

Microsoft Academic Search

Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We

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



Information happenings: Performing reflexive organizational research  

Microsoft Academic Search

This article is an experiment in organizational narration. The adoption of a novel literary form enables the author to address certain contemporary themes in the reflexive presentation and reporting of organizational research. In pursuit of an alternative mode of expression, the notion of the ‘Happening’ is found to be a helpful rhetorical device. ‘Happenings’ serve as a vehicle for the

Peter Case



Cardiopulmonary baroreceptors affect reflexive startle eye blink  

Microsoft Academic Search

Baroafferent signals originating from the ‘high pressure’ arterial vascular system are known to impact reflexive startle eye blink responding. However, it is not known whether baroafferent feedback of the ‘low pressure’ cardiopulmonary system loading status exerts a similar effect.Lower Body Negative Pressure (LBNP) at gradients of 0, ?10, ?20, and ?30mm Hg was applied to unload cardiopulmonary baroreceptors. Acoustic startle

S. Richter; A. Schulz; J. Port; T. D. Blumenthal; H. Schächinger



Taking Control of Reflexive Social Attention  

ERIC Educational Resources Information Center

|Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also…

Ristic, Jelena; Kingstone, Alan



Control of reflexive saccades following hemispherectomy.  


Individuals who have undergone hemispherectomy for treatment of intractable epilepsy offer a rare and valuable opportunity to examine the ability of a single cortical hemisphere to control oculomotor performance. We used peripheral auditory events to trigger saccades, thereby circumventing dense postsurgical hemianopia. In an antisaccade task, patients generated numerous unintended short-latency saccades toward contralesional auditory events, indicating pronounced limitations in the ability of a single hemicortex to exert normal inhibitory control over ipsilateral (i.e., contralesional) reflexive saccade generation. Despite reflexive errors, patients retained an ability to generate correct antisaccades in both directions. The prosaccade task revealed numerous contralesional express saccades, a robust contralesional gap effect, but the absence of both effects for ipsilesional saccades. These results indicate limits to the saccadic control capabilities following hemispherectomy: A single hemicortex can mediate antisaccades in both directions, but plasticity does not extend fully to the bilateral inhibition of reflexive saccades. We posit that these effects are due to altered control dynamics that reduce the responsivity of the superior colliculus on the intact side and facilitate the release of an auditory-evoked ocular grasp reflex into the blind hemifield that the intact hemicortex has difficulty suppressing. PMID:20617888

Reuter-Lorenz, Patricia A; Herter, Troy M; Guitton, Daniel



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



The nociceptive withdrawal reflex: normative values of thresholds and reflex receptive fields.  


Assessments of spinal nociceptive withdrawal reflexes can be used in human research both to evaluate the effect of analgesics and explore pain mechanisms related to sensitization. Before the reflex can be used as a clinical tool, normative values need to be determined in large scale studies. The aim of this study was to determine the reference values of spinal nociceptive reflexes and subjective pain thresholds (to single and repeated stimulation), and of the area of the reflex receptive fields (RRF) in 300 pain-free volunteers. The influences of gender, age, height, weight, body-mass index (BMI), body side of testing, depression, anxiety, catastrophizing and parameters of Short-Form 36 (SF-36) were analyzed by multiple regressions. The 95% confidence intervals were determined for all the tests as normative values. Age had a statistically and quantitatively significant impact on the subjective pain threshold to single stimuli. The reflex threshold to single stimulus was lower on the dominant compared to the non-dominant side. Depression had a negative impact on the subjective pain threshold to single stimuli. All the other analyses either did not reveal statistical significance or displayed quantitatively insignificant correlations. In conclusion, normative values of parameters related to the spinal nociceptive reflex were determined. This allows their clinical application for assessing central hyperexcitability in individual patients. The parameters investigated explore different aspects of sensitization processes that are largely independent of demographic characteristics, cognitive and affective factors. PMID:19505833

Neziri, Alban Y; Andersen, Ole K; Petersen-Felix, Steen; Radanov, Bogdan; Dickenson, Anthony H; Scaramozzino, Pasquale; Arendt-Nielsen, Lars; Curatolo, Michele




Microsoft Academic Search

Real-time scheduling is both based on a broad theoretical background and available through a multitude of tools and infrastructures. The central input parameters to this discipline are the demand for execution time and the real- time conditions given as deadlines or periods. The former has attracted a lot of research efforts, mainly in the scope of worst case execution time

Dieter Z


Impact of aging on long-term ocular reflex adaptation.  


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




Microsoft Academic Search

A shallow, RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)- contaminated aquifer at Naval Submarine Base Bangor has been characterized as predominantly manganese-reducing, anoxic with local pockets of oxic conditions. The potential contribution of microbial RDX degradation to localized decreases observed in aquifer RDX concentrations was assessed in sediment microcosms amended with (U- 14 C) RDX. Greater than 85% mineralization of 14 C-RDX to 14 CO2

Paul M. Bradley; Richard S. Dinicola


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


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

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



Spontaneous and reflex activity of facial muscles in dystonia, Parkinson's disease, and in normal subjects  

PubMed Central

OBJECTIVE—The blink rate is an index which can be easily obtained during the clinical examination, but it has not yet been properly standardised. The present study was undertaken to collect data on the age dependent development of this index and on possible abnormalities in Parkinson's disease and dystonia.?METHODS—The blink rate and the rate of perioral movements were measured in 156 normal controls, 51 patients with Parkinson's disease, 48 patients with spasmodic torticollis, 14 patients with generalised dystonia, and 12 patients with focal hand or leg dystonias and have been correlated with the results of testing the orbicularis oculi reflex, the palmomental reflex, and the perioral reflex.?RESULTS—No age related effects were found for the blink rate and perioral movements but all the reflexes showed age dependent variations. It is sufficient to measure the blink rate for one minute, provided standardised conditions are applied. Blink rate and perioral movement rate were positively correlated in patients and controls. The blink rate was significantly increased in spasmodic torticollis and decreased in Parkinson's disease. In generalised dystonia the blink rate was increased but in hand and leg dystonia the blink rate was normal. The reflex tests did not significantly differ between the subject groups except for the orbicularis oculi reflex, which was hyperexitable in Parkinson's disease.?CONCLUSION—Measuring the blink rate can assist the diagnosis of extrapyramidal disorders as a soft sign, but is not very sensitive. The group differences found indicate a decrease of the blink rate and perioral movements in hypokinetic and an increase in hyperkinetic extrapyramidal disorders such as spasmodic torticollis and generalised dystonias. This may be of interest for future pathophysiological studies.??

Deuschl, G.; Goddemeier, C.



[About the effect of alcohol and tiredness on the activity of tendon reflexes (author's transl)].  


In order to estimate the combined effect of ethanol and fatigue on the activity of tendon reflexes, the mechanical threshhold and the latency of the patellar tendon, the radial and the biceps reflexes as well as the time of contraction of the musculus quadriceps femoris was investigated in men, with an ethanol level in blood at 80 mg % during elimination-period, and with tired subjects meaning that they hade done their usual daywork and had been awake for about 20 to 22 hours. The group, consisting of 21 male students, was then investigated under both these conditions. The patellar reflex was elicited by a specially constructed reflexhammer, by which the mechanical power could by measured exactly, from the angle of the position the hammer was released from and its known weight. The latency and the muscular contraction time were registered with electrodes on the skin by an oscillograph. The mechanical threshhold of the patellar, biceps and radial reflexes and the latency of there reflexes were significantly and equally impaired by ethanol as well as by fatigue. The combination of both these factors resulted in an almost exactly additional effect. The contractiontime of the m. quadriceps was prolonged more by fatigue than by ethanol. Comparing these results with fromer findings, a depressing effect of the formatio reticularis of the brainstem on the activity of the spinal motorcells is to be discussed. This impairment of neuro-muscular coordination and activity obviously is dangerous for drivers. It should especially be noted, that the effect of a wake period of 20 to 22 hours can be compared with that of a bloodlevel of 80 mg % ethanol as to the impairment of the tendon reflexes. PMID:1217209

Joachim, H; Weyer, H H



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.



Analysis of the reflexive feedback control loop during posture maintenance.  


In previous work it has been shown in posture experiments of the human arm that reflexive dynamics were substantial for narrow-band stochastic force disturbances. The estimated reflex gains varied substantially with the frequency content of the disturbances. The present study analyses a simplified linear model of the reflexive feedback control loop, to provide an explanation for the observed behaviour. The model describes co-activation and reflexive feedback. The task instruction 'minimize the displacements' is represented mathematically by a cost function that is minimized by adjusting the parameters of the model. Small-amplitude displacements allow the system to be analysed with a quasilinear approach. The optimization results clarify the limited effectiveness of reflexive feedback on the system's closed-loop behaviour, which emanates from the time delay present in the reflex loops. For low-frequency inputs less than 5 Hz, boundary-stable solutions with high reflex gains are predicted to be optimal. Input frequencies near the system's eigenfrequency (about 5 Hz), however, would be amplified and result in oscillatory behaviour. As long as the disturbance does not excite these frequencies, boundary stability will be optimal. The predicted reflex gains show a striking similarity with the estimated reflex gains from the experimental study. The present model analysis also provides a clear explanation for the negative reflex gains, estimated for near-sinusoidal inputs beyond 1.5 Hz. PMID:11205350

de Vlugt, E; van der Helm, F C; Schouten, A C; Brouwn, G G



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


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

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



Osteopathic medical considerations of reflex sympathetic dystrophy.  


Review of current medical literature reveals little understanding of the physiology underlying the complex signs and symptoms that accompany reflex sympathetic dystrophy (RSD). The author surveyed the osteopathic medical literature and found a significant body of research documenting the physiology of somatic dysfunction. The manifestations of upper thoracic somatic dysfunction are strikingly similar to those of RSD and may offer insight into its heretofore unexplained physiology of this disorder. PMID:9195791

Nelson, K E



Nasonasal reflexes, the nasal cycle, and sneeze  

Microsoft Academic Search

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

James N. Baraniuk; Dennis Kim




PubMed Central

1. Cutting one vagus nerve, while recording the pulmonary ventilation of each lung separately, has no unique effect on the ventilation of the denervated lung. Both lungs respond to unilateral vagotomy by an equivalent slowing and deepening of respiratory movement. 2. When the bronchus to one lung is blocked the first effect is a slowing and deepening of the respiratory movements recorded by the opposite lung. As oxygen want develops these movements become rapid and shallow. 3. With a combination of these two conditions, i.e., when the bronchus to one lung is blocked and its vagus nerve is severed, the pulmonary ventilation recorded by the opposite lung exhibits the same changes as may result from unilateral vagotomy alone, unaccompanied by occlusion of the bronchus. 4. From these facts it may be concluded that the slowing and deepening of breathing which follows unilateral vagotomy does not depend for its occurrence upon the passage of air in and out of the bronchus of the lung whose vagus nerve has been sectioned. 5. The slowing of respirations after occlusion of the bronchus to one lung and section of the corresponding vagus nerve still occurs even though the phrenic nerve on the same side has been divided. This indicates that the slowing of respirations following unilateral vagotomy does not depend on the movements of the diaphragm on the side of vagal section. 6. When the pulmonary artery to one lung has been ligated and the vagus nerve on the same side cut, the response of the other lung is the same as has been described, namely, its respiratory movements become slower and deeper. This is taken as evidence that the results of unilateral vagotomy are not dependent upon an intact pulmonary circulation. 7. The general conclusions from these experiments are that the slowing and deepening of respirations following unilateral vagotomy do not depend upon: (a) Passage of air in and out of the trachea. (b) Expansion and collapse of the lung. (c) Existence of a normal pulmonary circulation in the vagotomized lung. (d) Normal fluctuations in alveolar carbon dioxide tension, (e) Contraction and relaxation of the diaphragm on the side of vagotomy. 8. The slowing and deepening of respirations, alluded to, may be presumed to indicate that a normal reflex (the Hering-Breuer reflex) has been interrupted. Since this interruption occurs in spite of all the conditions enumerated under Paragraph 7, we must conclude that none of these conditions is essential to the existence of this reflex.

Moore, Richmond L.



Anorectal tightening reflex: role in fecal incontinence.  


The present study describes the clinical significance of the anorectal tightening reflex (ATR) in normal and incontinent subjects. It was examined in 16 healthy volunteers and 11 subjects incontinent to flatus and fluid stools; 5 of the latter had in addition fecal soiling. The rectum was distended by a condom inflated with carbon dioxide, while the rectal and rectal neck (RN) (anal canal) pressures were measured, and the external (EAS) and internal anal sphincter (IAS) EMG activity was recorded. The rectum was inflated at two rates: slow and rapid. In normal subjects, the RN pressure increased upon slow rectal inflation; the IAS EMG was augmented. Pudendal nerve block and phentolamine administration revealed that this pressure increase is due to increased IAS tone which tightens the RN against the slow rectal filling by the time adaptive reaction occurs. Rapid rectal filling evoked Gower's rectoinhibitory reflex. Thus, while increased IAS tone in the ATR protects against involuntary incontinence upon 'slow' rectal filling, the increased EAS tone of Gower's reflex protects in the case of 'rapid' filling. Of the 11 incontinent patients, the 5 with fecal soiling did not show ATR, and investigative results pointed to the IAS as being responsible for incontinence. The other 6 patients had normal ATR but nonresponsive EAS on rapid filling. Findings suggest that the ATR plays a role in maintaining continence during slow rectal distension and that a disordered ATR due to IAS dysfunction leads to fecal incontinence. Thus ATR may be useful as an investigative tool in anorectal disorders. PMID:8276040

Shafik, A



Diurnal H-reflex variation in mice.  


Mice exhibit diurnal variation in complex motor behaviors, but little is known about diurnal variation in simple spinally mediated functions. This study describes diurnal variation in the H-reflex (HR), a wholly spinal and largely monosynaptic reflex. Six mice were implanted with tibial nerve cuff electrodes and electrodes in the soleus and gastrocnemius muscles, for recording of ongoing and nerve-evoked electromyographic activity (EMG). Stimulation and recording were under computer control 24 h/day. During a 10-day recording period, HR amplitude varied throughout the day, usually being larger in the dark than in the light. This diurnal HR variation could not be attributed solely to differences in the net ongoing level of descending and segmental excitation to the spinal cord or stimulus intensity. HRs were larger in the dark than in the light even after restricting the evoked responses to subsets of trials having similar ongoing EMG and M-responses. The diurnal variation in the HR was out of phase with that reported previously for rats, but was in phase with that observed in monkeys. These data, supported by those in other species, suggest that the supraspinal control of the excitability of the HR pathway varies throughout the day in a species-specific pattern. This variation should be taken into account in experimental and clinical studies of spinal reflexes recorded at different times of day. PMID:16151781

Carp, Jonathan S; Tennissen, Ann M; Chen, Xiang Yang; Wolpaw, Jonathan R



Is inhibition of return a reflexive effect?  


The inhibition of return (IOR) phenomenon is routinely considered an effect of reflexive attention because the paradigm used to generate IOR employs peripheral cues that are uninformative as to where a target will appear. Because the cues are spatially unreliable it is thought that there is no reason for attention to be committed volitionally to them, and hence, the IOR effect is considered reflexive. What has been generally overlooked, however, is that the cues provide reliable temporal information as to when a target will occur. This predictive information is used by participants to prepare volitionally for when a target is likely to appear. We investigated whether the IOR effect is a product of the volitional application of attention to peripheral cues for the use of their temporal information. To test this idea we rendered the temporal information provided by peripheral cues unreliable. While this eliminated participants using the cues volitionally, it did not abolish the IOR phenomenon. These data demonstrate two new findings. First, the IOR effect is fundamentally a reflexive phenomenon. Second, when peripheral cues are not used volitionally, the IOR effect is attenuated. Together, the present findings indicate that the IOR effect can be modulated by volitional (top-down) processes but it is not the product of them. We argue that an intimate link between fronto-parietal regions and the superior colliculus provide a functional neural mechanism for this volitional effect to impact IOR. PMID:15923001

Tipper, Christine; Kingstone, Alan



Inluence of eye motion on adaptive modifications of the vestibulo-ocular reflex in the rat  

Microsoft Academic Search

While sustained retinal slip is assumed to be the basic conditioning stimulus in adaptive modifications of the vestibulo-ocular reflex (VOR) gain, several observations suggest that eye motion-related signals might also be involved. We oscillated pigmented rats over periods of 20 min around the vertical axis, at 0.3 Hz and 20°\\/s peak velocity, in different retinal slip and\\/or eye motion conditions

Gabriel M. Gauthier; Claudio de'Sperati; Filippo Tempia; Evelyne Marchetti; Piergiorgio Strata



Effects of electric and magnetic transcranial stimulation on long latency reflexes  

Microsoft Academic Search

The interaction of transcranial electric and magnetic brain stimulation with electrically elicited shortand long latency reflexes (LLR) of hand and fore-arm flexor muscles has been investigated in normal subjects. In the first paradigm, the motor potential evoked in thenar muscles by transcranial stimulation was conditioned by median nerve stimulation at various conditioning-test intervals. At short intervals (electric: 5–12.5 ms, magnetic:

G. Deuschl; R. Michels; A. Berardelli; E. Schenck; M. Inghilleri; C. H. Lücking



The irradiation of a tactile conditioned reflex in man  

Microsoft Academic Search

The experiment was devised to clear up the doubts raised by Loucks concerning the evidence for irradiation. Human subjects, naked and isolated from extraneous cues, were subjected to tactile stimulation on the shoulder, small of back, thigh, and calf by means of electrically operated vibratory stimulators of special design. The unconditioned stimulus was an electric shock though the right wrist,

M. J. Bass; C. L. Hull



Soleus Stretch Reflex Inhibition in the Early Swing Phase of Gait Using Deep Peroneal Nerve Stimulation in Spastic Stroke Participants  

Microsoft Academic Search

Objectives: To investigate the feasibility of inhibiting the stretch reflex of the soleus muscle by a conditioning stimulus applied to the deep peroneal nerve in spastic stroke participants during the early swing phase of gait. - Materials and Methods: This study investigated the effect of an electrical conditioning stimulus applied to the deep peroneal nerve on the magnitude at the

Marco M. Voormolen; Michel Ladouceur; Peter H. Veltink; Thomas Sinkjaer



Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes?  

PubMed Central

Intention tremor is related to lesions in the cerebellum or connected pathways. Intention tremor amplitude decreased after peripheral arm cooling in patients with multiple sclerosis (MS), likely caused by a reduction of muscle spindle afferent inflow, while amplitude increased when muscle spindles were artificially stimulated by tendon vibration. This study investigated the contribution of peripheral reflexes to the generation of MS intention tremor. Tendon reflexes of biceps, triceps, and brachioradialis, muscles were measured, using an electromechanical triggered reflex hammer. MS patients with (n = 17) and without (n = 17) upper limb intention and 18 healthy controls were tested. Latency of brachioradialis, biceps, and triceps tendon reflexes was greater in MS patients with tremor than in healthy controls and MS patients without tremor (except for the triceps reflex). Peak and peak-to-peak amplitude were not different between groups. It is concluded that tendon reflexes were delayed but not enlarged in MS patients with tremor.

Feys, Peter; Helsen, Werner; Ilsbroukx, Stephan; Meurrens, Tom



Postauricular reflex responses to pictures varying in valence and arousal.  


Reflexes are modulated by emotions. Much research has revealed that the startle reflexive eyeblink response is modulated by emotion, particularly in response to pictures of emotional scenes. Investigations of other reflexes are limited. Recently, research suggested that the postauricular reflex in response to a startling noise was modulated by emotion. In particular, pleasant stimuli enhanced the postauricular reflex. However, these first investigations were limited: One experiment demonstrated only a marginal difference between the pleasant stimuli and neutral stimuli and the other lacked the typical neutral scene comparison. The present experiment was designed to assess whether significant emotion versus neutral differences would occur. Results demonstrated that pleasant stimuli, regardless of arousal level, evoked larger postauricular reflex activation than neutral and unpleasant emotional stimuli. PMID:19226306

Gable, Philip A; Harmon-Jones, Eddie



Bio-reflex-based robot adaptive motion controlling theory  

Microsoft Academic Search

The environment adaptability of robot motion can be effectively improved with bio-reflex theory which is a new research direction of robot motion-control. The paper introduces the basic theory of complete adaptive motion of robot with bio-reflex mechanism. As for the motion control of the robot, the traditional and the bio-reflex control methods are compared. The concept of a single system

Xiuli Zhang; Haojun Zheng; Guanghong Duan; Liyao Zhao



Do social statuses affect the startle reflex in male mice?  


Usual housing conditions lead to dominance hierarchy forming between male mice. The situation produces physiological and behavioural differences between dominants and subordinates. The goal of the present study was to assess stress responses, and possible changes in prepulse inhibition (PPI) of the startle reflex in dominant and subordinate male mice. Three weeks of daily social interactions led to stable aggressive dominance in 11 pairs of male NMRI mice. Stress levels were assessed by measuring faecal corticosterone metabolites (FCM), a non-invasive technique for monitoring hormonal changes in response to specific situations, with repeated sampling of each animal. The analysis of FCM levels showed greater stress in subordinate males at the beginning of the experiment, as the hierarchy was being established, but by the end of the experiment, FCM levels were reduced and similar in both dominants and subordinates. No significant differences were found in the startle response or PPI. PMID:22728306

Coudereau, J-P; Sreng, L; Palme, R; Touma, C; Pratte, M



Baroreceptor reflex is suppressed in rats that develop hyperalgesia behavior after nerve injury.  


The baroreceptor reflex buffers autonomic changes by decreasing sympathetic activity and increasing vagal activity in response to blood pressure elevations, and by the reverse actions when the blood pressure falls. Because of the many bidirectional interactions of pain and autonomic function, we investigated the effect of painful nerve injury by spinal nerve ligation (SNL) on heart rate (HR), blood pressure (BP) and their regulation by the baroreceptor reflex. Rats receiving SNL were separated into either a hyperalgesic group that developed sustained lifting, shaking and grooming of the foot after plantar punctate nociceptive stimulation by pin touch or a group of animals that failed to show this hyperalgesic behavior after SNL. SNL produced no effect on resting BP recorded telemetrically in unrestrained rats compared to control rats receiving either skin incision or sham SNL. However, two tests of baroreceptor gain showed depression only in animals that developed sustained hyperalgesia after SNL. The animals that failed to develop hyperalgesia after SNL were found to have elevations in HR both before and for the first 4 days after SNL, and HR variability analysis gave indications of decreased vagal control of resting HR and elevated sympatho-vagal balance at these same time intervals. In human patients, other research has shown that blunted baroreceptor reflex sensitivity predicts poor outcome during conditions such as hypertension, congestive heart failure, myocardial infarction, and stroke. If baroreceptor reflex suppression is also found in human subjects during chronic neuropathic pain, this may adversely affect survival. PMID:19729245

Gemes, Geza; Rigaud, Marcel; Dean, Caron; Hopp, Francis A; Hogan, Quinn H; Seagard, Jeanne



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



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

NASA Astrophysics Data System (ADS)

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

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



Reflex discharges into thoracic white rami elicited by somatic and visceral afferent excitation  

PubMed Central

1. Reflex discharges in white rami (WR) were elicited by single-shock stimulation of dorsal roots (DR), splanchnic (SPL) and intercostal nerves (IC). 2. The reflexes have been compared in anaesthetized cats with intact neuraxis, after mid-brain transection and after high cord transection. The brain stem can maintain moderate inhibition of the WR responses, but strong inhibition of IC responses. After cord transection all reflexes are released again. 3. Stimulation of ventromedial medullary reticular substance could completely, and independently, inhibit maximal SPL-to-WR and IC-to-WR reflexes. 4. Carotid sinus distension did not reduce WR responses, indicating that the major part of the volley is not in vasoconstrictor fibres. 5. Central delay of DR-to-WR responses is longer than delay of DR-to-IC responses and is unchanged by transections of the neuraxis at mid-brain or high spinal levels. 6. There was no facilitation of WR responses by a prior conditioning volley in the visceral or somatic afferent pathway in contrast to early facilitation of the IC responses.

Coote, J. H.; Downman, C. B. B.; Weber, W. V.



Further Evidence for the Independent Reflex-Eliciting and Reflex-Inhibiting Effects of a Startle-Blink Eliciting Stimulus  

Microsoft Academic Search

A small change in the environment (a prepulse) that just precedes a startle-eliciting stimulus can reduce the size of the elicited reflex, but a prepulse does not appear to diminish the ability of the startle-eliciting stimulus to depress a startle response elicited a little later. The reflex-eliciting and reflex-modifying effects of startle stimuli seem to be independent. However, most support

E. Evan Krauter; Bridgette C. Cruickshank; Michael C. Avery



Effects of ischaemia upon reflex electromyographic responses evoked by stretch and vibration in human wrist flexor muscles.  

PubMed Central

1. The reflex electromyographic responses evoked in a wrist flexor muscle, flexor carpi radialis (f.c.r.), by forcible extension of the wrist ('stretch') and by vibration of the flexor tendon have been studied in normal subjects. Reflexes were elicited during the maintenance of a low level of voluntary flexor contraction (5% maximum). Stretch regularly produced a relatively prolonged (ca. 100 ms duration) increase in e.m.g. activity which was usually divisible into short-latency (ca. 25 ms, M1) and long-latency (ca. 50 ms, M2) peaks. Vibration produced a single, phasic peak, at short latency, with no sign of an accompanying long-latency wave comparable to the M2 stretch response. 2. Ischaemia was induced by inflation of a blood-pressure cuff around the upper arm and its effects upon the reflex patterns were studied. During ischaemia M1 stretch responses showed a more rapid and pronounced decline than did M2 responses and were abolished before voluntary power was appreciably affected. Vibration-evoked short-latency peaks changed in an essentially parallel manner to M1 stretch reflexes. During recovery from ischaemia M2 reflexes were restored before short-latency responses. 3. The patterns of reflex reductions in e.m.g. upon withdrawal of stimulation were also studied. Such troughs in activity, under non-ischaemic conditions, regularly commenced at short latency and were of relatively small amplitude. The records of several of the subjects, and particularly ones obtained during ischaemia, suggested that release of stretch (with concomitant stretch of antagonists) could elicit an additive, long-latency decline in e.m.g. The existence of any such separate, delayed component was never observed upon termination of vibration. 4. Measurements of changes in the latencies and durations of reflex components, accompanying the progression of ischaemia, indicated that depression of early reflex activity resulted in part from increases in the latencies of these initial peaks but predominantly reflected simultaneous and separate reductions in their amplitudes. 5. The generation of short-latency reflexes by stretch and vibration, both of which stimuli powerfully excite muscle spindle primary endings, and the marked susceptibility of these responses to ischaemia supports their being mediated by group Ia afferents. The contrasting behaviour of M2 stretch responses, both regarding their absence with vibration and their resistance to ischaemia, suggests that they depend crucially upon a separate group of reflex afferents.(ABSTRACT TRUNCATED AT 400 WORDS)

Cody, F W; Goodwin, C N; Richardson, H C



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

ERIC Educational Resources Information Center

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

Dyke, Martin



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

ERIC Educational Resources Information Center

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

Dyke, Martin



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


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 foot sole, and pain intensity ratings and EMG responses were recorded. RRF sensitivity and probability maps were derived, and RRF areas were calculated. During FSI, the stimulation intensities were constant and the pain ratings dropped significantly (p<0.01). In contrast, during ASI the pain ratings were stable, but there was a significant increase in the stimulation intensities (p<0.01). None of the paradigms altered significantly the RRF areas, but the FSI paradigm had lower estimation error (p<0.01). In all cases, the estimation error remained under 10% and 5% after five and ten repetitions, respectively. The 2nd stimulus in the train consistently rendered larger and more reliable RRF areas than the 1st stimulus. The present analysis can be useful in order to identify the most adequate stimulation parameters and quantification variables for RRF assessment in experimental and clinical pain research. PMID:20934351

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



Flexor reflex for assessment of common interneurone activity in spasticity.  


The purpose of this investigation was to evaluate the alterations of flexor reflex parameters in spasticity and the possibilities to take advantage of them as a method for assessment of common interneurone activity. Clinical and electromyographical examinations were performed on 120 patients with spastic hemiparesis after stroke. The flexor reflex was obtained after supramaximal electrostimulation of the tibial nerve behind the ankle. The stimulus consisted of 50 msec train of 1 msec duration pulses given at 100 Hz. The reflex activity was recorded from the tibialis anterior muscle. As all patients were with hemiparesis the healthy side was used as a control. The patients were subdivided into four groups, each treated with different myorelaxants (Baclofen, Sirdalud, Myolastan and electroacupuncture). After about 25 days treatment the clinical and electromyographic examinations were repeated. The flexor reflex was recorded with two clearly distinguishable responses on the healthy, as well as on the spastic side. On the spastic side a reflex with prolonged latencies and durations, as well as with decreased amplitudes and thresholds of both reflex responses was found. On the spastic side the first reflex response had higher threshold than the second one, while on the healthy side it was vice versa. Moderate correlations were found between most of the reflex parameters. No correlations were found between the reflex parameters and the degree of spasticity. Only after Baclofen treatment all reflex parameters tended to normalized. After treatment with Myolastan, Sirdalud and electroacupuncture only the second response's duration shortened. In conclusion the flexor reflex is a sensitive method for assessment of altered common interneurone activity in spasticity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1493777

Milanov, I G



Body Posture: Experimental-Physiological Investigations of the Reflexes Involved in Body Posture, Their Cooperation and Disturbances,  

National Technical Information Service (NTIS)

Contents: General outline; Stato-kinetic reflexes; Switching phenomena in the central nervous system; Position reflexes; Combination of the neck and labyrinth reflexes; Compensatory eye positions; Righting reflexes; Effects of unilateral labyrinth extirpa...

R. Magnus



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

PubMed Central

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

Hsiao, An-Fu; Longhurst, John C.



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

Microsoft Academic Search

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

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



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


Variability in Hoffmann and Tendon Reflexes in Healthy Male Subjects.  

National Technical Information Service (NTIS)

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...

E. Good S. Do M. Jaweed



Reflections on Reflexivity and Critical Reflection as Critical Research Practices  

Microsoft Academic Search

This article explores reflexivity and critical reflection as they were applied during an exploratory study of the psychiatric and mental health service experiences of lesbian and queer women. Reflexivity and critical reflection are centered as critical research practices toward recognizing and responding to micropractices of power and power relations in the interviewing relationship, structural forms of power and its impact

Andrea Daley



Recovery of the Rectoanal Inhibitory Reflex After Restorative Proctocolectomy  

Microsoft Academic Search

PURPOSE: The rectoanal inhibitory reflex has an important role in fecal sampling and discrimination of rectal contents. The aim of this study was to determine the significance of rectoanal inhibitory reflex after restorative proctocolectomy with ileal pouch-anal anastomosis for mucosal ulcerative colitis. METHODS: The medical records of 345 patients who underwent ileal pouch-anal anastomosis from September 1988 to May 1999

Naoto Saigusa; Bruce M. Belin; Hong-Jo Choi; Pascal Gervaz; Jonathan E. Efron; Eric G. Weiss; Juan J. Nogueras; Steven D. Wexner



Direct and consensual murine pupillary reflex metrics: Establishing normative values  

Microsoft Academic Search

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

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



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…

Hale, Bruce D.; And Others


The nociceptive flexion reflex in humans – review article  

Microsoft Academic Search

The nociceptive flexion reflex (NFR) is a physiological, polysynaptic reflex allowing for painful stimuli to activate an appropriate withdrawal response. NFR is easily measurable in clinical setting, and is a reliable and objective tool for measurement of an individual’s pain experience. An exhaustive review of the literature, covering multiple search engines, indicates that the NFR method is valuable in studying

V. Skljarevski; N. M. Ramadan



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



Lombard reflex during PAG-induced vocalization in decerebrate cats  

Microsoft Academic Search

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

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



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



Ethnic differences in the nociceptive flexion reflex (NFR)  

PubMed Central

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

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



Habituation and sensitization of protective reflexes: Dissociation between cardiac defense and eye-blink startle  

Microsoft Academic Search

We examined the habituation and recovery of two protective reflexes, cardiac defense and eye-blink startle, simultaneously elicited by a white noise of 500ms as a function of the time interval between stimulus presentations. Participants were 90 volunteers (54 women) randomly distributed into 6 inter-trial interval (ITI) conditions. They all received three presentations of the stimulus with a time interval of

José Luís Mata; Sonia Rodríguez-Ruiz; Elisabeth Ruiz-Padial; Graham Turpin; Jaime Vila



Static ocular counterroll reflex in skew deviation  

PubMed Central

Objective: The static ocular counterroll (OCR) reflex generates partially compensatory torsional eye movements during head roll. It is mediated by the utricle in the inner ear. Skew deviation is a vertical strabismus thought to be caused by imbalance in the utriculo-ocular pathway. We hypothesized that if skew deviation is indeed caused by damage to this reflex pathway, patients with skew deviation would show abnormal OCR. Methods: Eighteen patients with skew deviation caused by brainstem or cerebellar lesions and 18 normal participants viewed a target at 1 m. Ocular responses to static passive head roll-tilts of approximately 20° were recorded using search coils. Static OCR gain was calculated as the change in torsional eye position divided by the change in head position during sustained head roll. Perception of the subjective visual vertical (SVV) was also measured. Results: Group mean OCR gain was reduced by 45% in patients. At an individual level, OCR gains were asymmetric between eyes and between torsional directions in 90% of patients. In addition, the hypotropic eye incyclotorting gain was lower than the hypertropic eye excyclotorting gain during head roll toward the hypotropic eye in 94% of patients. No consistent pattern of gain asymmetry was found during head roll toward the hypertropic eye. The SVV was tilted toward the hypotropic eye. Conclusion: Static OCR gain is significantly reduced in skew deviation. Interocular and directional gain asymmetries are also prevalent. The asymmetries provide further evidence that disruption of the utriculo-ocular pathway is a mechanism for skew deviation.

Chandrakumar, M.; Blakeman, A.; Goltz, H.C.; Sharpe, J.A.



Psychologic aspects of childhood reflex neurovascular dystrophy.  


Psychosocial factors in 21 families with children affected by reflex neurovascular dystrophy were studied. Each family was interviewed and given a battery of standardized psychologic tests. Two distinct types of families were identified. Fifteen families showed high internal cohesion, expressiveness, and organization and low levels of conflict. Six families showed high overt conflict with low levels of family cohesion, expressiveness, and organization. In all families parental enmeshment with the patient was present. Marital discord was present in 12 families. Thirteen patients had significant school problems (ten had learning disabilities). Although most of the children were described as especially bright, only four had above average intelligence test scores. Four had a history of sexual abuse. The patients and their mothers perceived the health problem as significantly worse than did children with arthritis from whom similar scores had been obtained. Possible role models with similar symptoms were reported by ten patients. These data support the concept that childhood reflex neurovascular dystrophy is frequently a stress-related disease; the therapeutic approach to treating these children and their families must take these psychosocial factors into account. PMID:3353192

Sherry, D D; Weisman, R



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


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



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

Microsoft Academic Search

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,

José A. Biurrun Manresa; John Hansen; Ole K. Andersen



Electromyographic and reflex study in idiopathic and symptomatic trigeminal neuralgias: latency of the jaw and blink reflexes  

PubMed Central

Recorded jaw reflexes were studied in 51 normal subjects. In addition, the blink and jaw reflexes combined with masseteric electromyography were recorded in 17 unselected patients with facial pain. Six of these patients, including two without neurological anomalies, showed electrodiagnostic anomalies. The method proved valuable for differentiation between idiopathic and symptomatic trigeminal neuralgia. Images

Visser, B. W. Ongerboer De; Goor, C.



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

Microsoft Academic Search

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

Keith C. Hayes



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



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


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

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



Inhibitory role of the spinal cholinergic system in the control of urethral continence reflex during sneezing in rats.  


AIMS: The urethral continence reflex during stress conditions such as sneezing or coughing is an important mechanism preventing stress urinary incontinence (SUI). Although the spinal noradrenergic and serotonergic pathways are known to modulate this reflex activity, the role of spinal cholinergic pathways in the control of urethral continence reflex has not been elucidated. We therefore investigated the effect of intrathecal administration of an acetylcholine esterase (AChE) inhibitor, which increases ACh in synaptic terminals, and anti-cholinergic agents on the sneeze-induced urethral reflex in rats. METHODS: Female SD rats were anesthetized with urethane. Urethral function was evaluated during sneezing induced by insertion of the rat whisker into the nostril. Effects of an AChE inhibitor, neostigmine, and muscarinic or nicotinic receptor antagonists administered at the level of L6-S1 spinal cord were examined. RESULTS: Neostigmine dose-dependently and significantly decreased the amplitude of urethral responses during sneezing (A-URS) with an approximately 70% reduction at 3?nmol, without changing urethral baseline pressure. The neostigmine-induced decrease in A-URS was significantly reversed by pretreatment with atropine (nonselective muscarinic receptor antagonist), methoctramine (M2 receptor antagonist) or 4-DAMP (M3 receptor antagonist), but not with pirenzepine (M1 receptor antagonist), tropicamide (M4 receptor antagonist), or mecamylamine (nicotinic receptor antagonist). CONCLUSIONS: These results indicate that an increase in endogenous ACh in the lumbosacral spinal cord inhibits the sneeze-induced urethral continence reflex via activation of M2 and/or M3-muscarinic receptors, implying the inhibitory role of spinal cholinergic pathways in the control of urethral continence reflex under stress conditions such as sneezing. Neurourol. Urodynam. © 2013 Wiley Periodicals, Inc. PMID:23754327

Yoshikawa, Satoru; Kitta, Takeya; Miyazato, Minoru; Sumino, Yasuhiro; Yoshimura, Naoki



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



Bremsstrahlung target optimization for reflex triodes  

NASA Astrophysics Data System (ADS)

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

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



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



Spontaneous oscillations in a nonlinear delayed-feedback shunting model of the pupil light reflex  

NASA Astrophysics Data System (ADS)

We analyze spontaneous oscillations in a second-order delayed-feedback shunting model of the pupil light reflex. This model describes in a simple fashion the nonlinear effects of both the iris and retinal parts of the reflex pathway. In the case of smooth negative feedback, linear stability analysis is used to determine the conditions for a Hopf bifurcation in the pupil area as a function of various neurophysiological parameters of the system such as the time delay and the strength of neural connections. We also investigate oscillation onset in the case of piecewise negative feedback and obtain an analytical expression for the period of oscillations. Finally, complex periodic behavior is shown to arise in the presence of mixed feedback.

Bressloff, P. C.; Wood, C. V.



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

NASA Astrophysics Data System (ADS)

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

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



Aerial righting reflexes in flightless animals.  


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



Sex differences in nociceptive withdrawal reflex and pain perception.  


Experimentally induced pain often reveals sex differences, with higher pain sensitivity in females. The degree of differences has been shown to depend on the stimulation and assessment methods. Since sex differences in pain develop anywhere along the physiological and psychological components of the nociceptive system, we intended to compare the nociceptive flexion reflex (NFR) as a more physiological (spinal) aspect of pain procession to the verbal pain report of intensity and unpleasantness as the more psychological (cortical) aspect. Twenty female and twenty male healthy university students were investigated by use of nociceptive flexion reflex threshold (staircase method) after electrical stimulation of the N. suralis. Furthermore, we assessed supra-threshold reflex responses (latency, amplitude and area) by applying 10 stimuli 5 mA above reflex threshold. Following each stimulation, the subjects provided pain ratings of intensity and unpleasantness on a visual analogue scale. Females exhibited marked lower nociceptive flexion reflex thresholds than males, while the supra-threshold reflex response tailored to the individual reflex threshold did not show any significant differences. The verbal pain ratings, corrected for NFR threshold, were not found to differ significantly. The large sex differences in nociception that were present in NFR threshold but not in the pain ratings corroborate the hypothesis that spinal processes contribute substantially to sex differences in pain procession. PMID:16338828

Mylius, Veit; Kunz, Miriam; Schepelmann, Karsten; Lautenbacher, Stefan



Sensorimotor transformation in cat nociceptive withdrawal reflex system.  


The withdrawal reflex system of higher vertebrates has been extensively used as a model for spinal sensorimotor integration, nociceptive processing and plasticity. In the rat, the nociceptive withdrawal reflex system appears to have a modular organization. Each reflex module controls a single muscle or a few synergistic muscles, and its cutaneous receptive field corresponds to the skin area withdrawn upon contraction of the effector muscle(s) when the limb is in the standing position. This organization principle is at odds with the 'flexion reflex' concept postulated from cat studies. To assess the generality of the modular organization principle we have therefore re-examined the cutaneous input to the withdrawal reflex system of the cat. The cutaneous receptive fields of hindlimb and forelimb muscles were mapped using calibrated noxious pinch stimulation and electromyographic recording technique in barbiturate anaesthetized animals. The investigated muscles had specific cutaneous receptive fields that appeared to correspond to the area of the skin withdrawn upon contraction of the muscle when the limb is in the standing position. The spatial organization of receptive fields in the cat was similar to that in the rat. However, differences in gain properties of reflexes to some anatomically equivalent muscles in the two species were observed, possibly reflecting adaptations to the biomechanics characteristic of the digitigrade and plantigrade stance in cats and rats, respectively. Implications of the findings for the generality of the modular organization of the withdrawal reflex system and for its adaptive properties are discussed. PMID:10594658

Levinsson, A; Garwicz, M; Schouenborg, J



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

Microsoft Academic Search

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

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



The recto-levator reflex: the description of a new reflex and its clinical application. Preliminary report.  


This communication embodies the description of a technique of recording a new reflex which I call "recto-levator reflex". The study was performed on 32 normal volunteers. The technique comprises the introduction of a balloon connected with a catheter into the rectum. A concentric needle electrode was introduced into the levator ani. The rectal balloon was distended and the levator myoelectric activity was recorded. In 12 patients, the procedure was repeated after levator infiltration with xylocaine or saline. When the rectal balloon was inflated with air, the levator muscle contracted. Levator contraction increased with increasing rectal distension. Anesthetized muscle did not respond, while saline-infiltrated muscle responded to rectal distension. Latency of the reflex was calculated. The recto-levator reflex seems to play an important role at defecation. On rectal distension with stools, levator contraction opens the rectal neck. Changes in the latency or amplitude of the reflex would indicate a defect in the reflex pathway. The reflex may thus prove of diagnostic significance in defecation disorders. PMID:8339517

Shafik, A



Postauricular and Superior Auricular Reflex Modulation during Emotional Pictures and Sounds  

PubMed Central

The postauricular reflex is a relatively new psychophysiological measure of appetitive emotional processing during picture viewing. However, the degree to which other auricular (i.e., superior and anterior auricular) muscles might exhibit reflexive activity congruent with that found in the postauricular muscle has not been investigated, nor has the robustness of postauricular reflex modulation across stimulus modality. In this study, postauricular reflexes were the only reflexes that showed consistent emotional modulation across ears and genders. Additionally, postauricular reflexes were significantly modulated for both emotional pictures and sounds; in both cases, postauricular reflexes were greatest during pleasant stimuli.

Benning, Stephen D.



Quantified reflex strategy using an iPod as a wireless accelerometer application.  


A primary aspect of a neurological evaluation is the deep tendon reflex, frequently observed through the patellar tendon reflex. The reflex response provides preliminary insight as to the status of the nervous system. A quantified reflex strategy has been developed, tested, and evaluated though the use of an iPod as a wireless accelerometer application integrated with a potential energy device to evoke the patellar tendon reflex. The iPod functions as a wireless accelerometer equipped with robust software, data storage, and the capacity to transmit the recorded accelerometer waveform of the reflex response wirelessly through email for post-processing. The primary feature of the reflex response acceleration waveform is the maximum acceleration achieved subsequent to evoking the patellar tendon reflex. The quantified reflex strategy using an iPod as a wireless accelerometer application yields accurate and consistent quantification of the reflex response. PMID:23366427

LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren



Relating reflex gain modulation in posture control to underlying neural network properties using a neuromusculoskeletal model  

Microsoft Academic Search

During posture control, reflexive feedback allows humans to efficiently compensate for unpredictable mechanical disturbances.\\u000a Although reflexes are involuntary, humans can adapt their reflexive settings to the characteristics of the disturbances. Reflex\\u000a modulation is commonly studied by determining reflex gains: a set of parameters that quantify the contributions of Ia, Ib\\u000a and II afferents to mechanical joint behavior. Many mechanisms, like

Jasper Schuurmans; Frans C. T. van der Helm; Alfred C. Schouten



Nociceptive reflexes and the somatic dysfunction: a model.  


A model of somatic dysfunction is developed in which restriction in mobility and autonomic, visceral, and immunologic changes are produced by pain-related sensory neurons and their reflexes. Nociceptors are known to produce muscular guarding reactions, as well as autonomic activation, when musculoskeletal or visceral tissue is stressed or damaged. This guarding causes abnormal musculoskeletal position and range of motion. Local inflammatory responses and autonomic reflexes further reinforce nociceptor activity, maintaining restriction. Nociceptive autonomic reflexes also evoke changes in visceral and immunologic function. Finally, maintenance of muscles, joints, and related tissues in an abnormal guarding position causes changes in the connective tissues, solidifying the abnormal position. Stretching these tissues into a normal range of motion will restimulate the nociceptor, reflexly reinforcing the somatic dysfunction. This model has evolved from Korr's neurologic model but emphasizes the nociceptor and its reflexes as a source of the connective tissue, circulatory, visceral, and immunologic changes seen in the somatic dysfunction. PMID:2211195

Van Buskirk, R L



21 CFR 890.1450 - Powered reflex hammer.  

Code of Federal Regulations, 2013 CFR

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



Reflex Responses to Ligament Loading: Implications for Knee Joint Stability.  

National Technical Information Service (NTIS)

To assess the neuromuscular reflex responses to loading of knee ligaments, we applied an abducting positional deflection to the fully extended knee using a servomotor, and recorded EMG activity in preactivated quadriceps and hamstrings muscles with surfac...

Y. Y. Dhaher A. D. Tsoumanis W. Z. Rymer



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



Aging delays strategic modulation of the fixation reflex.  


Stimuli that project onto central vision facilitate maintenance of eye position, a phenomenon called the fixation reflex. Endogenous control over this fixation reflex enables one to willfully look away. The current study investigated whether these behaviors, which are important for effective visual orienting, change with advancing age. Previous research established that patients with frontal lobe damage exhibit weaker fixation reflexes and reduced control over this reflex. In light of brain atrophy occurring during healthy aging, we predicted similar but less robust changes in neurologically healthy older relative to young adults. The results generally supported this prediction, which has negative implications for performance of time-sensitive visual-orienting tasks. (PsycINFO Database Record (c) 2013 APA, all rights reserved). PMID:23586356

Bos, Hannah; Machado, Liana



Reflex Modification and the Assessment of Sensory Dysfunction.  

National Technical Information Service (NTIS)

The chapter states, reflex modification of the startle response is a technique that can provide rapid, objective, and quantitative assessments of sensorimotor function. Advantages of the technique involve the ability to test animals rapidly, test without ...

K. M. Crofton



Impaired control of the oculomotor reflexes in Parkinson's disease  

PubMed Central

To investigate the role of the basal ganglia in integrating voluntary and reflexive behaviour, the current study examined the ability of patients with Parkinson's disease to voluntarily control oculomotor reflexes. We measured the size of the fixation offset effect (the reduction in saccadic reaction time when a fixation point is removed) during a block of pro- and a block of anti-saccades. Healthy controls showed the expected reduction of the FOE during the anti-saccades, which results from efforts to suppress reflexive eye movements (a preparatory set characterized by increased internal control and reduced external control). However, there was no reduction of the FOE in the anti-saccade task in Parkinson's patients, indicating that they are impaired in exerting control over oculomotor reflexes.

van Koningsbruggen, Martijn G.; Pender, Tom; Machado, Liana; Rafal, Robert D.



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


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



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


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



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



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


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

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



Common principles of sensory encoding in spinal reflex modules and cerebellar climbing fibres  

PubMed Central

An important step towards understanding the function of olivo-cerebellar climbing fibres must be to clarify what they signal. We suggest that climbing fibres projecting to paravermal cerebellum mediate highly integrated sensorimotor information derived from activity in spinal withdrawal reflex modules acting on single forelimb muscles. To test this hypothesis, cutaneous nociceptive receptive fields of spinal reflex modules were mapped and compared to those of climbing fibres. Quantitative methods were used both for mapping and for comparing receptive fields. The organization of muscle afferent input converging on individual climbing fibres was analysed in the light of results from receptive field comparisons. Individual cutaneous receptive fields in the two systems were readily matched. Matched pairs were highly similar with regard to detailed distributions of sensitivity: correlation coefficient r = 0.85; overlap of receptive field foci 72 % (average values). The olivary targets of muscle afferents from a given muscle were mainly climbing fibres with cutaneous receptive fields similar to that of the muscle itself, but to a lesser extent also other climbing fibres. In conclusion, paravermal climbing fibres apparently convey information integrating (i) cutaneous input to an individual spinal withdrawal reflex module, (ii) muscle afferent input from the output muscle of that module and (iii) muscle afferent input from muscles that constitute the output of functionally related modules. This suggests that an individual climbing fibre signals cutaneous sensory events reflecting activity of a single muscle conditional upon the functional state of the muscle itself and that of functionally related muscles.

Garwicz, Martin; Levinsson, Anders; Schouenborg, Jens



Spinal reflex excitability changes after cervical and lumbar spinal manipulation  

Microsoft Academic Search

Background context: Spinal manipulation (SM) is a commonly employed nonoperative treatment modality in the management of patients with neck, low back or pelvic pain. One basic physiologic response to SM is a transient decrease in motoneuron activity as assessed using the Hoffmann reflex (H-reflex) technique. Previous research from our laboratory indicates that both SM with a high-velocity, low-amplitude thrust and

J. Donald Dishman; Jeanmarie Burke



Interaction between Ocular Stabilization Reflexes in Patients with Whiplash Injury  

Microsoft Academic Search

PURPOSE. In the past few decades, the automobile has become an increasingly more popular means of transport, which has led to an increasing number of rear-end collisions and conse- quently has resulted in more patients with whiplash-associated disorders (WADs). Recently, it was found that the gain of one of the ocular stabilization reflexes—the cervico-ocular reflex (COR)—is elevated in patients with

Inger Montfoort; Willem P. A. Kelders; Jos N. van der Geest; Inger B. Schipper; Louw Feenstra; Chris I. de Zeeuw; Maarten A. Frens



Modulation of human cutaneous reflexes during rhythmic cyclical arm movement  

Microsoft Academic Search

The organization and pattern of cutaneous reflex modulation is unknown during rhythmic cyclical movements of the human upper\\u000a limbs. On the assumption that these cyclic arm movements are central pattern generator (CPG) driven as has been suggested\\u000a for leg movements such as walking, we hypothesized that cutaneous reflex amplitude would be independent of electromyographic\\u000a (EMG) muscle activation level during rhythmic

E. Paul Zehr; Romeo Chua



Cortical and cerebellar activation induced by reflexive and voluntary saccades  

Microsoft Academic Search

Reflexive saccades are driven by visual stimulation whereas voluntary saccades require volitional control. Behavioral and\\u000a lesional studies suggest that there are two separate mechanisms involved in the generation of these two types of saccades.\\u000a This study investigated differences in cerebral and cerebellar activation between reflexive and self-paced voluntary saccadic\\u000a eye movements using functional magnetic resonance imaging. In two experiments (whole

Caroline K. L. Schraa-Tam; Phillippus van Broekhoven; Josef N. van der Geest; Maarten A. Frens; Marion Smits; Aad van der Lugt



Comparison of Single Bout Effects of Bicycle Training Versus Locomotor Training on Paired Reflex Depression of the Soleus H-Reflex After Motor Incomplete Spinal Cord Injury  

Microsoft Academic Search

Phadke CP, Flynn SM, Thompson FJ, Behrman AL, Trimble MH, Kukulka CG. Comparison of single bout effects of bicycle training versus locomotor training on paired reflex depression of the soleus H-reflex after motor incomplete spinal cord injury.

Chetan P. Phadke; Sheryl M. Flynn; Floyd J. Thompson; Andrea L. Behrman; Mark H. Trimble; Carl G. Kukulka



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


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

Lapole, Thomas; Pérot, Chantal



Measurement of the lateral thoracic reflex latency in ponies.  


Lateral thoracic nerve reflex latencies values were measured in ponies using a simple, non-invasive technique. The reflex was elicited using an external triggering hammer attached to an electrodiagnostic unit. The resulting evoked, compound muscle action potentials were recorded with electrodes, which were placed over the 6th ribs or 11th rib level with the axilla. Two superimposed repeats of 4 signal-averaged sweeps of 50 or 100 milliseconds were recorded and the estimated reflex pathway was measured for each subject in order to calculate the reflex latencies and latency velocities. Mean left and right 6th rib peak latencies were not significantly different from each other (P = .609), but left 6th rib latencies were shorter than those recorded from the 11th rib (P < .0001), substantiating the existence of an indirect (central) pathway to the reflex. The calculated left and right 6th rib latency velocities were not significantly different from each other (P = .58) but left 6th rib latency velocities were different from left 11th rib (P = .009). The calculated latency velocities were within the broad range for corticospinal tract motor conduction velocities and comparable to magnetic motor evoked latency velocities. The use of lateral thoracic reflex latency measurements to objectively identify the site of spinal cord lesions is discussed. PMID:9686392

Hahn, C N; Mayhew, I G; Washbourne, J R


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


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

Wurm, Barbara



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


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



Impaired Sacculocollic Reflex in Lateral Medullary Infarction  

PubMed Central

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

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



Artificial balancer - supporting device for postural reflex.  


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



Frequency dependence of vestibuloocular reflex thresholds  

PubMed Central

How the brain processes signals in the presence of noise impacts much of behavioral neuroscience. Thresholds provide one way to assay noise. While perceptual thresholds have been widely investigated, vestibuloocular reflex (VOR) thresholds have seldom been studied and VOR threshold dynamics have never, to our knowledge, been reported. Therefore, we assessed VOR thresholds as a function of frequency. Specifically, we measured horizontal VOR thresholds evoked by yaw rotation in rhesus monkeys, using standard signal detection approaches like those used in earlier human vestibular perceptual threshold studies. We measured VOR thresholds ranging between 0.21 and 0.76°/s; the VOR thresholds increased slightly with frequency across the measured frequency range (0.2–3 Hz). These results do not mimic the frequency response of human perceptual thresholds that have been shown to increase substantially as frequency decreases below 0.5 Hz. These reported VOR threshold findings could indicate a qualitative difference between vestibular responses of humans and nonhuman primates, but a more likely explanation is an additional dynamic neural mechanism that does not influence the VOR but, rather, influences perceptual thresholds via a decision-making process included in direction recognition tasks.

Haburcakova, Csilla; Lewis, Richard F.



Frequency dependence of vestibuloocular reflex thresholds.  


How the brain processes signals in the presence of noise impacts much of behavioral neuroscience. Thresholds provide one way to assay noise. While perceptual thresholds have been widely investigated, vestibuloocular reflex (VOR) thresholds have seldom been studied and VOR threshold dynamics have never, to our knowledge, been reported. Therefore, we assessed VOR thresholds as a function of frequency. Specifically, we measured horizontal VOR thresholds evoked by yaw rotation in rhesus monkeys, using standard signal detection approaches like those used in earlier human vestibular perceptual threshold studies. We measured VOR thresholds ranging between 0.21 and 0.76°/s; the VOR thresholds increased slightly with frequency across the measured frequency range (0.2-3 Hz). These results do not mimic the frequency response of human perceptual thresholds that have been shown to increase substantially as frequency decreases below 0.5 Hz. These reported VOR threshold findings could indicate a qualitative difference between vestibular responses of humans and nonhuman primates, but a more likely explanation is an additional dynamic neural mechanism that does not influence the VOR but, rather, influences perceptual thresholds via a decision-making process included in direction recognition tasks. PMID:22072512

Haburcakova, Csilla; Lewis, Richard F; Merfeld, Daniel M



Cardiopulmonary baroreceptors affect reflexive startle eye blink.  


Baroafferent signals originating from the 'high pressure' arterial vascular system are known to impact reflexive startle eye blink responding. However, it is not known whether baroafferent feedback of the 'low pressure' cardiopulmonary system loading status exerts a similar effect. Lower Body Negative Pressure (LBNP) at gradients of 0, -10, -20, and -30mm Hg was applied to unload cardiopulmonary baroreceptors. Acoustic startle noise bursts were delivered 230 and 530ms after spontaneous R-waves, when arterial baroreceptors are either loaded or unloaded. Eye blink responses were measured by EMG, and psychomotor reaction time by button pushes to startle stimuli. The new finding of this study was that unloading of cardiopulmonary baroreceptors increases startle eye blink responsiveness. Furthermore, we replicated the effect of relative loading/unloading of arterial baroreceptors on startle eye blink responsiveness. Effects of either arterial or cardiopulmonary baroreceptor manipulations were not present for psychomotor reaction times. These results demonstrate that the loading status of cardiopulmonary baroreceptors has an impact on brainstem-based CNS processes. PMID:19799919

Richter, S; Schulz, A; Port, J; Blumenthal, T D; Schächinger, H



Enhancement of carotid chemoreceptor reflex and cardiac chemosensitive reflex in the acute phase of myocardial infarction of the anesthetized rabbit  

Microsoft Academic Search

.   In the acute phase of cardiac ischemia there is an imbalance of the autonomic outflow with a depression of the baroreceptor\\u000a reflex. Carotid chemoreceptor stimulation evokes an increase on arterial blood pressure and bradycardia in the anesthetized\\u000a and paralyzed animal. The activation of cardiac chemosensitive fibers elicit the Bezold-Jarisch reflex comprising a decrease\\u000a of arterial blood pressure and bradycardia.

I. Rocha; L. B. Rosário; E. I. de Oliveira; M. A. Barros; L. Silva-Carvallho



The effect of whole body vibration on the H-reflex, the stretch reflex, and the short-latency response during hopping.  


The effect of whole body vibration (WBV) on reflex responses is controversially discussed in the literature. In this study, three different modalities of reflex activation with increased motor complexity have been selected to clarify the effects of acute WBV on reflex activation: (1) the electrically evoked H-reflex, (2) the mechanically elicited stretch reflex, and (3) the short-latency response (SLR) during hopping. WBV-induced changes of the H-reflex, the stretch reflex, and the SLR during hopping were recorded in the soleus and gastrocnemius muscles and were analyzed before, during (only the H-reflex), immediately after, 5 min and 10 min after WBV. The main findings were that (1) the H-reflexes were significantly reduced during and at least up to 5 min after WBV, (2) the stretch reflex amplitudes were also significantly reduced immediately after WBV but recovered to their initial amplitudes within 5 min, and (3) the SLR during hopping showed no vibration-induced modulation. With regard to the modalities with low motor complexities, the decreased H- and stretch reflex responses are assumed to point toward a reduced Ia afferent transmission during and after WBV. However, it is assumed that during hopping, the suppression of reflex sensitivity is compensated by facilitatory mechanisms in this complex motor task. PMID:23802287

Ritzmann, R; Kramer, A; Gollhofer, A; Taube, W



A method of Reflexive Balancing in a Pragmatic, Interdisciplinary and Reflexive Bioethics.  


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



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


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

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



Exercise pressor reflex function is altered in spontaneously hypertensive rats  

PubMed Central

In hypertension, exercise elicits excessive elevations in mean arterial pressure (MAP) and heart rate (HR) increasing the risk for adverse cardiac events and stroke during physical activity. The exercise pressor reflex (a neural drive originating in skeletal muscle), central command (a neural drive originating in cortical brain centres) and the tonically active arterial baroreflex contribute importantly to cardiovascular control during exercise. Each of these inputs potentially mediates the heightened cardiovascular response to physical activity in hypertension. However, given that exercise pressor reflex overactivity is known to elicit enhanced circulatory responses to exercise in disease states closely related to hypertension (e.g. heart failure), we tested the hypothesis that the exaggerated cardiovascular response to exercise in hypertension is mediated by an overactive exercise pressor reflex. To test this hypothesis, we used a rat model of exercise recently developed in our laboratory that selectively stimulates the exercise pressor reflex independent of central command and/or the arterial baroreflex. Activation of the exercise pressor reflex during electrically induced static muscle contraction in the absence of input from central command resulted in significantly larger increases in MAP and HR in male spontaneously hypertensive rats as compared to normotensive Wistar-Kyoto rats over a wide range of exercise intensities. Similar findings were obtained in animals in which input from both central command and the arterial baroreflex were eliminated. These findings suggest that the enhanced cardiovascular response to exercise in hypertension is mediated by an overactive exercise pressor reflex. Potentially, effective treatment of exercise pressor reflex dysfunction may reduce the cardiovascular risks associated with exercise in hypertension.

Smith, Scott A; Williams, Maurice A; Leal, Anna K; Mitchell, Jere H; Garry, Mary G



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


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

Schaller, B




PubMed Central

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

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



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.



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.



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


Somatosympathetic reflex and acupuncture-related analgesia.  


Both acute and chronic pains correspond to nociceptive substances (NSs), which are naturally produced and metabolized by the organism experiencing the pains. The accumulation of NSs in regional tissues triggers a series of pathophysiological reactions and initiates certain threats to the health and the quality of human life. Pharmacological intervention is the most popular treatment for pain relief, which is achieved by either reducing the production of NSs or blocking the transmission of nociceptive signals through the nervous system, but no drug has been developed for the elimination of NSs. Therefore, improving blood circulation to eliminate NSs in painful tissues is an alternative strategy for pain relief. Acupuncture has been proved to be effective for the treatment of certain kinds of pain, but the mechanisms therein remain unclear. The effectiveness of acupuncture analgesia is also variable owing to the uncertainty surrounding the mechanism and the poor standardization of the technique. There is some evidence that acupuncture may induce pain relief by changing the regional blood flow through somatosympathetic reflex (SSR). Therefore, when exploring the mechanisms of SSR in detail, it is helpful to clarify the mechanisms of acupuncture analgesia and to develop a more standardized and effective protocol for acupuncture analgesia. Increasing evidence has suggested that both sympathetic activity and stimulation-induced SSR are differentially controlled in an organ-specific and activity-dependent manner. Vasomotor outflow, which involves the regulation of impaired regional blood circulation, is also differentially controlled in response to specific somatic stimulation. Therefore, we vigorously review the relations between SSR and acupuncture-related analgesia so that we can develop a targeted pain therapy where in certain areas of the body undergo site-specific somatic stimulation, which in turn, can adjust the impaired regional blood circulation. PMID:20359125

Huang, Chung-Shin; Tsai, Yuan-Feen



Pharmacological and Anatomical Analysis of Fear Conditioning Using the Fear-Potentiated Startle Paradigm  

Microsoft Academic Search

Pharmacological and anatomical analysis of fear conditioning using the fear-potentiated startle paradigm are reviewed. This test measures conditioned fear by an increase in the amplitude of a simple reflex (the acoustic startle reflex) in the presence of a cue previously paired with a shock. This paradigm offers a number of advantages as an alternative to most animal tests of fear

Michael Davis



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


The aim of this study was to investigate the acute effects of prior exercise (warm-up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min) and (3) after a 10-min warm-up run on a treadmill. Tendon tap reflex force was elicited in the triceps surae of the right leg by means of a standardized reflex hammer and measured in a custom-built fixture. Electromyographic (EMG) signals were recorded with surface electrodes over the medial head of the gastrocnemius (G) and the soleus (S). Low coefficients of variation within subjects contrasted with high between-subject variations, indicating highly individual reflex characteristics. After stretching, reductions in the peak force (-5%; P < 0.05), the force rise rate (-8%; P < 0.01), the half relaxation rate (-5%; N.S.), the EMG amplitudes (G, -16%; S, -17%; P < 0.01) and integrals (G, -15%; S, -18%; P < 0.01), and an increase in EMG latencies (G, +3%; S, +1%; P < 0.01), were found compared with the values obtained without prior exercise. After running, the peak force reached the values obtained without prior exercise (-2%; N.S.), the force rise rate and half relaxation rate increased by 8 and 12%, respectively (P < 0.01), and the impulse (force-time integral; -12%), EMG amplitudes (G, -20%; S, -23%; P < 0.01), integrals (G, -18%; S, -23%; P < 0.01) and latencies (G, -1%; S, -2%; P < 0.01) decreased significantly. The changes in the force characteristics observed after the stretching treatment indicate improved muscle compliance that might reduce the risk of injury. On the other hand, the changes after the additional warm-up run had a more pronounced influence with regard to improved force development and a decreased EMG activity, which can be viewed as a performance-enhancing effect. PMID:8850574

Rosenbaum, D; Hennig, E M



Inhibitory effect of needle penetration on vibration-induced finger flexion reflex in humans  

PubMed Central

Background Vibration-induced finger flexion reflex (VFR) in the upper extremity is inhibited by needle insertion acupuncture to the large intestine 4 (LI4) at the hand. This claim has a limitation because the inhibitory effect is deduced only from reduction in the maximum finger flexion (FF) force during the tonic flexion reflex by vibratory stimulation after acupuncture. Methods The study was a crossover design with two conditions—acupuncture and control—to which 16 healthy volunteers were subjected. VFR in the upper extremity was induced by applying vibratory stimulation on the volar side of the middle fingertip of the right hand, before and after acupuncture at the right LI4 in 16 healthy volunteers. We measured the area under the curve (AUC) of finger flexion force and surface electromyogram (EMG) in the flexor muscles, in addition to the maximum FF force during vibratory stimulation. We compared AUC, surface EMG and maximum FF force in the acupuncture condition with those in the control condition. We also estimated the correlation between AUC, surface EMG and maximum FF force. Results AUC, surface EMG and maximum FF force were significantly reduced (p <0.01) after acupuncture compared with those of the control group. A strong correlation was observed in maximum FF force versus AUC (r=0.98, p <0.01) and surface EMG (r=0.77, p <0.01). Conclusions Acupuncture at ipsilateral LI4 inhibited tonic activities in the finger flexor muscles during VFR, which suggests that afferent input with needle penetration has inhibitory effect on the motor neuronal activities in the reflex circuits of VFR.

Takakura, Nobuari; Yajima, Hiroyoshi; Takayama, Miho; Kawase, Akiko; Homma, Ikuo



Deficits of reflexive attention induced by abduction of the eye.  


Attention mediates access of sensory events to higher cognitive systems and can be driven by either top-down voluntary mechanisms or in a bottom-up, reflexive fashion by the sensory properties of a stimulus. The exact mechanisms underlying these different modes of attention are controversial, but both types of attention appear to be tightly coupled to the systems used for the control of eye-movements. Indeed, recent data indicates that patients with opthalmoplegia (paralysis of the eyes) have difficulty voluntarily attending to locations to which saccades cannot be made (Craighero, Carta, & Fadiga, 2001) and experimentally induced opthalmoplegia disrupts voluntary attention in normal participants. However, the extent to which reflexive attention is mediated by the ability to make eye-movements in normal participants remains unclear. Here, we address this issue by investigating the effect of an experimentally induced opthalmoplegia on voluntary and reflexive attentional orienting during visual search. We observed that abducting the eye into the temporal hemifield elicited deficits of both voluntary and reflexive attention for targets that appeared beyond the oculomotor range. This result confirms the link between oculomotor control and voluntary attention observed in opthalmoplegic patients and demonstrates for the first time that reflexive attention is mediated by the ability to make eye-movements in normal participants. PMID:20036265

Smith, Daniel T; Ball, Keira; Ellison, Amanda; Schenk, Thomas



Changes of Reflex, Non-reflex and Torque Generation Properties of Spastic Ankle Plantar Flexors Induced by Intelligent Stretching.  


Spasticity, contracture, and muscle weakness are major sources of disability in stroke. Changes of torque-generating capacity as well as reflex and non-reflex properties of ankle plantar flexors induced by strenuous stretching in chronic hemiplegia were investigated. Twelve subjects with a unilateral stroke and 10 healthy controls underwent 30 minutes of strenuous intelligent stretching treatment. Reflex and non-reflex components of spastic hypertonia and force-generating capacity of ankle plantar flexors were investigated. Dorsiflexion (DF) range of motion (ROM) was increased (p=0.002) and passive stiffness and passive resistant torque of the spastic muscles were decreased (p=0.004 and 0.007, respectively), while reflex hyper-excitability diminished slightly but with no statistical significance. The maximal voluntary contraction (MVC) torque of the spastic ankle plantar flexors was increased after the forceful stretching treatment (p=0.041). In contrast, the stretching treatment of the healthy plantar flexors did not change any of the variables measured before and after stretching. The stroke subjects who gained more DF ROM or larger decrement of stiffness achieved greater increment of the peak torque generation after the stretching (r=0.597 with p=0.040 and r=-0.746 with p=0.005, respectively). These results suggest that the strenuous dynamic stretching could improve the force-generating capacity of spastic muscles as well as reduce the passive stiffness and increase ROM. PMID:17281024

Chung, S; Bai, Z; Rymer, W Z; Zhang, L Q



Cardiac inhibitory reflex as a cause/mechanism of death.  


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



A reflexive toy-model for financial market  

NASA Astrophysics Data System (ADS)

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

Palatella, Luigi



Blink reflex elicited by auditory stimulation in the rabbit.  


The pathway of the blink reflex, elicited by auditory stimulation, was investigated electrophysiologically. The reflex was recorded as microvibrations of the eyelid and was named the auditory-evoked eyelid microvibration (AMV). Pharmacophysiological studies suggest that AMV is closely related to the midbrain reticular formation and studies of electrical lesions in the midbrain reticular formation support this. Lesions in several parts of the central nervous system provide evidence that the inferior colliculus has an important role in AMV, and the cerebral cortex may have an inhibitory influence. Studies of brainstem transections indicate that the reflex pathway of AMV exists between the lower midbrain and the upper medulla. Because of its ease and simplicity, AMV is believed to be a useful test for evaluation of the function of the brainstem. PMID:3783188

Hori, A; Yasuhara, A; Naito, H; Yasuhara, M



Field trials with low power lasers concerning the blink reflex.  


Laser belonging to class 2 emit in the visible part of the spectrum. The power is limited to 1 mW in the CW mode. Up to now the protection of the eyes has been supposed to be given by the blink reflex for incidentally intrabeam viewing in many regulations. In 3 field trials with 519 test persons we have shown that only 15.9% at 670 nm, 17.2% at 635 nm, and 20.3% at 532 nm had a blink reflex under laser irradiation. An analysis of the results showed neither significant differences concerning the age and the gender of the test persons nor whether they were wearer of glasses or right sighted. The frequent lack of the blink reflex demands organizational measures like instruction using laser class 2 in medical and other applications. PMID:12465249

Reidenbach, H D; Dollinger, K; Hofmann, J



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


In Xenopus laevis tadpoles, we studied the static vestibuloocular reflex (rVOR) in relation to modifications of the gravitational environment to find basic mechanisms of how altered gravitational forces (AGF) affect this reflex. Animals were exposed to microgravity during space flight or hypergravity (3g) for 4 to 12 days. Basic observations were that (1)the development of the rVOR is significantly affected by altered gravitational conditions, (2) the duration of 1g-readaptation depends on the strength of the test stimulus, (3) microgravity induces malformations of the body which are related to the rVOR depression. Future studies are based on the hypotheses (1) that the vestibular nuclei play a key roll in the adaptation to AGF conditions, (2) that the stimulus transducing systems in the sense organ are affected by AGF conditions, and (3) that fertilized eggs will be converted to normal adults guided by physiological and morphological set points representing the genetic programs. Developmental retardation or acceleration, or otherwise occurring deviations from standard development during embryonic and postembryonic life will activate genes that direct the developmental processes towards normality. PMID:11799991

Sebastian, C; Horn, E



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

NASA Astrophysics Data System (ADS)

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

Sebastian, C.; Horn, E.



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



Hydrogen peroxide-induced cardiovascular reflexes. Role of hydroxyl radicals  

Microsoft Academic Search

Mesenteric ischemia reflexly activates thecardiovascular system. Inaddition, mesenteric ischemia and reperfusion generate reactive oxygenspecies. However, theability ofthese short-lived reactive oxygen species togenerate cardiovascular reflexes isunknown. We therefore investigated cardiovascular reflexes induced byserosal application ofhydrogen peroxide (H202) tothegallbladder, stomach, orduodenumin anesthetized cats.Serosal application ofhydrogen peroxide (44gmol) tothegallbladder (n=14) significantly (p<0.05) increased mean arterial blood pressure(MAP)by37±6mm Hg,left ventricular dP\\/dt by1,893+±416 mm Hg\\/sec,

GL Stahl; B Halliwell; JC Longhurst



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


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



Phase and task-specific modulation of soleus H -reflexes during drop-jumps and landings  

Microsoft Academic Search

H-reflexes in the soleus muscle were previously shown to be decreased in drop-jumps at the instant of the short latency response\\u000a (SLR) of the stretch reflex when falling height was increased. The aim of the present study was to elucidate task-specific\\u000a modulation of H-reflexes during drop-jumps in more detail. Therefore, soleus H-reflex excitability was compared in drop-jumps from three different

Christian Leukel; Albert Gollhofer; Martin Keller; Wolfgang Taube



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

Microsoft Academic Search

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

Amandeep Takhar; Pepukayi Chitakunye



A model-based approach for the quantification of H reflex depression in humans  

Microsoft Academic Search

The analysis of the H reflex, a homologue of the stretch reflex, is useful as an aid in understanding certain neurologic disorders as it reflects some aspects of spinal cord neuronal circuitry and dynamics. Here, a dynamical model is used to describe the H reflex depression in humans in response to trains of stimuli. The model describes the interplay of

A. F. Kohn; M. K. Floeter; M. Hallett



Augmentation of vagal reflex bradycardia by central ? 1 adrenoceptors in the cat  

Microsoft Academic Search

Vagal reflex bradycardia was induced in anaesthetized cats with high level spinal axotomy by electrical stimulation of either the carotid sinus nerves or a depressor nerve. In both preparations reflex bradycardia increased with the rate of stimulation. Injection of 1 µg\\/kg clonidine into a lateral cerebral ventricle augmented reflex bradycardia in response to carotid sinus nerve stimulation while the same

Hisato Kitagawa; Alexander Walland



Influence of resting sympathetic activity on reflex sympathetic responses in normal man  

Microsoft Academic Search

Reflex sympathetic responses to physiologic stress are known to be modulated by afferent sensory mechanisms. However, the potential influence of baseline sympathetic tone on these reflex-mediated responses is unclear. To test the hypothesis that the resting level of muscle sympathetic nerve activity (MSNA) influences reflex-mediated changes in MSNA in normal man, MSNA, blood pressure (BP), central venous pressure (CVP), and

Hans P. Schobel; Ron M. Oren; Allyn L. Mark; David W. Ferguson



Somatotopical relationships between cortical activity and reflex areas in reflexology: A functional magnetic resonance imaging study  

Microsoft Academic Search

We examined the somatotopical relationship between cortical activity and sensory stimulation of reflex areas in reflexology using functional magnetic resonance imaging. Three reflex areas on the left foot, relating to the eye, shoulder, and small intestine were stimulated during the experiment. A statistical analysis showed that reflexological stimulation of the foot reflex areas corresponding to the eye, shoulder, and small

Tomomi Nakamaru; Naoki Miura; Ai Fukushima; Ryuta Kawashima



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.



[Localization of level of lesions in internuclear ophthalmoplegia through assessment of masseter and blink reflex].  


The masseter and blink reflexes were investigated in 100 patients with internuclear ophthalmoplegia due to multiple sclerosis (58 patients) or lacunar brainstem infarction (42 patients). In unilateral internuclear ophthalmoplegia, 38 of 60 patients (63.3%) had masseter reflex abnormalities, two patients (3.3%) showed changes of the blink reflex R1 component, and 13 patients (21.7%) combined alterations of the masseter reflex and the blink reflex R1 component. 46 (86.8%) of these 53 patients with electrophysiological abnormalities had unilateral changes, which were ipsilateral to the medial longitudinal fasciculus lesion in 42 patients (91.3%). In bilateral internuclear ophthalmoplegia, 24 of 40 patients (60.0%) had abnormalities of the masseter reflex, two (5.0%) showed changes of the blink reflex R1, and nine (22.5%) combined alterations of the masseter reflex and the blink reflex R1 component. 20 (57.1%) of these 35 patients with electrophysiological abnormalities had bilateral changes. Thus, masseter reflex abnormalities indicating midbrain lesions were seen in 63.3% and 60.0%, respectively, of unilateral and bilateral internuclear ophthalmoplegia. Blink reflex R1 component changes with or without impairment of the masseter reflex indicating rostral pontine to midpontine lesions occurred in 25.0% and 27.5%, respectively. These figures correspond to the results of postmortem examinations and to theoretical considerations based on the length of the medial longitudinal fasciculus. PMID:1462069

Thömke, F; Hopf, H C



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



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

Microsoft Academic Search

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

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



Pain, Negative Mood, and Perceived Support in Chronic Pain Patients: A Daily Diary Study of People With Reflex Sympathetic Dystrophy Syndrome  

Microsoft Academic Search

Chronic pain patients show substantial psychological distress, including depressed mood, anxiety, and anger. Nevertheless, the causal role of negative mood in the course of chronic pain conditions remains unclear. This study prospectively investigated the relationship between daily pain, negative mood, and social support in 109 people with reflex sympathetic dystrophy syndrome. Participants completed 28 daily diaries that included questions about

Scott I. Feldman; Geraldine Downey; Rebecca Schaffer-Neitz



Massage and stretching reduce spinal reflex excitability without affecting twitch contractile properties.  


Both stretching and massage can increase range of motion. Whereas the stretching-induced increases in ROM have been attributed to changes in neural and muscle responses, there is no literature investigating the ROM mechanisms underlying the interaction of stretch and massage. The objective of this paper was to evaluate changes in neural and evoked muscle responses with two types of massage and static stretching. With this repeated measures design, 30s of plantar flexors musculotendinous junction (MTJ) and tapotement (TAP) massage were implemented either with or without 1min of concurrent stretching as well as a control condition. Measures included the soleus maximum H-reflex/M-wave (H/M) ratio, as well as electromechanical delay (EMD), and evoked contractile properties of the triceps surae. With the exception of EMD, massage and stretch did not significantly alter triceps surae evoked contractile properties. Massage with and without stretching decreased the soleus H/M ratio. Both TAP conditions provided greater H/M ratio depression than MTJ massage while the addition of stretch provided the greatest inhibition. Both massage types when combined with stretching increased the duration of the EMD. In conclusion, MTJ and TAP massage as well as stretching decreased spinal reflex excitability, with TAP providing the strongest suppression. While static stretching prolongs EMD, massage did not affect contractile properties. PMID:23770003

Behm, David G; Peach, Ashley; Maddigan, Meaghan; Aboodarda, Saied Jalal; DiSanto, Mario C; Button, Duane C; Maffiuletti, Nicola A



Relationship between facial asymmetry and masseter reflex activity  

Microsoft Academic Search

Purpose: In this study, we evaluated the tonic vibration reflex (TVR) of the masseter muscles in patients with facial asymmetry. Subjects and Methods: The study was conducted with 10 volunteers without facial asymmetry and 12 orthognathic patients with facial asymmetry. Subjects were seated in a chair and held a stimulator composed of an electric motor and an acrylic bite block

Naoki Machida; Kazuhiro Yamada; Yoshiyuki Takata; Yoshiaki Yamada



A Reflective--Reflexive View of Women and Leadership  

ERIC Educational Resources Information Center

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

Moss, Glenda



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



Influence of the emetic reflex on vasopressin release in man  

Microsoft Academic Search

Influence of the emetic reflex on vasopressin release in man. The mechanisms underlying the frequent association of nausea and vomiting with elevations of plasma vasopressin (PAVP) were studied in man and rat. After oral water loads (N = 16), plasma osmolality fell in all human subjects and was associated with a decline in PAVP in 14 asymptomatic human subjects. In

John W Rowe; Ronald L Shelton; J Harold Helderman; Robert E Vestal; Gary L Robertson



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



Long-term depression of the human masseter inhibitory reflex  

Microsoft Academic Search

Long-term depression (LTD) of synaptic transmission is reliably induced by low-frequency stimulation (LFS) of nociceptive afferents in vitro. LTD can only exceptionally be induced in anesthetized animals. In order to fill the gap between the in vitro cell studies and the in vivo situation, the effects of LFS on the masseter inhibitory reflex (MIR) were investigated in man. Noxious LFS

Jens Ellrich; Anila Schorr



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



Diurnal Variations of the Achilles Reflex Time in Normal Man.  

National Technical Information Service (NTIS)

The Achilles tendon reflex time was recorded in the morning, at midday, and in the evening during five days in 18 normal sedentary subjects. Every recording measured the following intervals: SD (contraction time), DP (true half-relaxation time), SP (sum o...

J. A. Macarez



Affective modulation of the startle reflex following traumatic brain injury  

Microsoft Academic Search

Diminished emotional recognition, expression, and responsivity are frequent legacies of traumatic brain injury (TBI) that can have an adverse impact on relationships and psychosocial recovery. However, assessment of emotion responsivity is often difficult because many patients lack insight into their altered personality. To overcome this obstacle, we used a physiological measure of emotion responsivity, the startle reflex, to examine how

Claire Williams; Rodger L. Wood



Conducting Systematic Review in Education: A Reflexive Narrative  

ERIC Educational Resources Information Center

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…

Nind, Melanie



Recto-colic reflex: role in the defecation mechanism.  


As urge is felt and defecation starts, it is postulated that the colon continuously feeds the rectum with stools until the colon is empty. The relationship of rectal distension at defecation to colonic activity is not yet fully explored. The current communication studies this relationship in 11 patients (mean age 48.4+/-18.8 years, 6 men and 5 women) with transverse colostomy performed after transverse colectomy for cancer of the transverse colon. The rectum was distended by a condom-ended catheter in increments of 10 ml of H20, and the pressures in the right and left colon were measured by balloon catheters introduced through the colostomy. The test was repeated after anesthetizing the rectum or colon, respectively. Upon rectal distension up to sensation of urge, there was no colonic pressure response. At urge (mean distension volume of 160+/-36.7 ml), the left colonic pressure showed a significant rise (p<0.001), while the right colon revealed no response (p>0.05). Rectal distension during rectal or colonic anesthetization effected no colonic pressure response (p>0.05). The left colonic contraction upon rectal distension, being reproducible and absent with the anesthetized rectum or colon, postulates a reflex relationship which we call "recto-colic reflex". This reflex acts at defecation to feed the rectum successively with fecal material until the colon is emptied. Reflex derangement may play a role in defecation disorders. PMID:9028993

Shafik, A


Ia reflexes and EPSPs in human soleus motor neurones  

Microsoft Academic Search

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

T. S. Miles; K. S. Türker; T. H. Le



Treatment of Reflex Sympathetic Dystrophy (CRPS Type 1)  

Microsoft Academic Search

A blinded meta analysis was performed on randomized clinical trials (RCT) on the medicinal treatment of reflex sympathetic dystrophy (complex regional pain syndrome type I) to assess the methodological quality and quantify the analgesic effect of treatments by calculating individual and summary effect sizes. The internal validity of 21 RCTs was investigated and the quality weighted summary effect size was

Roberto S. G. M Perez; Gert Kwakkel; Wouter W. A Zuurmond; Jaap J de Lange



Instrumentalization Theory and Reflexive Design in Animal Husbandry  

Microsoft Academic Search

In animal husbandry in The Netherlands, as in a wide variety of other societal areas, we see an increased awareness of the fact that progress cannot be attained anymore by simply repeating the way we modernized this sector in the decades before, due to the multiplicity of the problems to be dealt with. The theory of reflexive modernization articulates this

A. P. Bos



Illustrations of the analytic memo as reflexivity for preservice teachers  

Microsoft Academic Search

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

Donna Kalmbach Phillips; Kevin Carr



Spinal reflex excitability changes after lumbar spine passive flexion mobilization  

Microsoft Academic Search

Background: Flexion distraction has gained increased credibility as a therapeutic modality for treatment of low back pain. Although important work in the area has elucidated the intradiskal pressure profiles during flexion distraction, the accompanying neural responses have yet to be described. Objective: The purpose of this pilot study was to assess neural reflex responses to motion with 3 degrees of

Ronald Bulbulian; Jeanmarie Burke; J. Donald Dishman



Conceptualisation of Terrorism in Modelling Tools: Critical Reflexive Approach  

Microsoft Academic Search

This paper outlines a critical reflexive approach to an assessment of modelling\\/simulation tools. The concepts of terrorism and terrorism threat in modelling literature are analysed and compared with the contesting definitions of terrorism in political science and counter-terrorism discourse. Possible social implications of using particular concepts of terrorism and terrorism threat are identified. This study discusses how modellers provide better

Lucy Resnyansky



Trigeminal reflexes and ingestive behavior in the rat  

Microsoft Academic Search

Used photographic, eletrophysiological, and neurobehavioral analyses in 3 experiments with 21 Wistar rats to examine the contribution of trigeminally mediated jaw-opening reflexes to the control of ingestive behavior. During eating and drinking, jaw opening was always preceded by a period of perioral contact with the food or water source (Exp I). Electrical and mechanical stimulation of perioral areas in Ss

H. Philip Zeigler; Kazue Semba; Mark F. Jacquin



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



Physiological tremor enhanced by manoeuvres affecting the segmental stretch reflex.  

PubMed Central

In view of recent evidence that physiological tremor can be enhanced by positive feedback via the segmental stretch reflex, several manoeuvres and procedures were employed to enhance the finger and hand tremor of healthy subjects--the purpose being to determine if tremorogenic effects, at least in part, are due to increase efficacy of the stretch reflex servo. Mechanical events during tremor (and during voluntary or electrically induced muscle twitches) were recorded together with EMG activity from wrist and finger flexor muscles and discharges from primary spindle endings in these muscles. Physiological tremor can be enhanced not only by manoeuvres which increase the gain of segmental stretch reflexes (Jendrassik manoeuvre) but also by manoeuvres which increase the contrast in spindle firing during stretch versus shortening phases of tremor, thus enhancing reflex modulation. Effects of the latter type can be achieved by procedures which alter mechanical twitch properties of extrafusal fibres (isoproterenol infusions and fatigue) and by procedures which involve application of spindle stimuli acting preferentially during stretch phases of tremor movements (muscle vibrations). Physiological tremor, which can be temporarily enhanced by an externally applied muscle perturbation, also becomes accentuated by those small "pseudo-myoclonic" jerks which occur in all normal subjects attempting to perform slow, smooth movements.

Young, R R; Hagbarth, K E



Reflex inhibition of canine inspiratory intercostals by diaphragmatic tension receptors  

PubMed Central

Electrical stimulation of phrenic afferent fibres in the dog elicits a reflex inhibition of efferent activity to the inspiratory intercostal muscles. However, electrical stimulation has a poor selectivity, so the sensory receptors responsible for this inhibition were not identified.In the present studies, cranial forces were applied during spontaneous inspiration to the abdominal surface of the central, tendinous portion of the canine diaphragm to activate tension mechanoreceptors in the muscle. Vagal afferent inputs were eliminated by vagotomy.The application of force to the central tendon caused a graded, reflex reduction in inspiratory intercostal activity, especially in external intercostal activity. This reduction was commonly associated with a decrease in inspiratory duration and was invariably attenuated after section of the cervical dorsal roots.In contrast, no change in inspiratory intercostal activity was seen when high frequency mechanical vibration was applied to the central tendon to stimulate diaphragmatic muscle spindles.These observations provide strong evidence that tension receptors in the diaphragm, but not muscle spindles, induce reflex inhibition of inspiratory intercostal activity. The expression of this reflex probably involves supraspinal structures.

De Troyer, Andre; Brunko, Eric; Leduc, Dimitri; Jammes, Yves



Contribution of stretch reflexes to locomotor control: a modeling study  

Microsoft Academic Search

It is known that the springlike properties of muscles provide automatic load compensation during weight bearing. How crucial is sensory control of the motor output given these basic properties of the locomotor system? To address this question, a neuromuscular model was used to test two hypotheses. (1) Stretch reflexes are too weak and too delayed to contribute significantly to weight-bearing.

S. Yakovenko; V. Gritsenko; A. Prochazka



Voluntary and reflexive eye movements to illusory lengths  

Microsoft Academic Search

Considerable debate surrounds the extent and manner that motor control is, like perception, susceptible to visual illusions. Using the Brentano version of the Müller-Lyer illusion, we measured the accuracy of voluntary and reflexive eye movements to the endpoints of equal length line segments that appeared different (Experiment 1) and different length line segments that appeared equal (Experiment 3). Voluntary and

Gregory J. Digirolamo; Jason S. McCarley; Arthur F. Kramer; Harry J. Griffin



Stress-Induced Enhancement of the Startle Reflex.  

National Technical Information Service (NTIS)

The goals of the research are to study neural systems involved in the production and inhibition of fear and anxiety. Previous research has found that the acoustic startle reflex is sensitive to both fear and stress. Many effects produced by fear or stress...

M. Davis



Subject instruction and long latency reflex responses to muscle stretch.  

PubMed Central

1. Surface electromyographic recordings were made in eight normal subjects from the isometrically contracting elbow flexors before and during forcible extension of the elbow through 7 degrees in 50-150 msec. 2. Weh the subjects were instructed prior (2-5 sec) to a forthcoming stretch to 'resist' or to 'let go', they could reliably enhance or suppress e.m.g. activity occurring between 40 and 70 msec from commencement of the stretch. Such e.m.g. activity represents a 'long-latency' (or 'M2') reflex response: it occurs with a latency longer than the spinal segmental monosynaptic reflex, but shorter than a voluntary reaction time. When the subjects were given their instructions (by means of a light) at the moment the stretch commenced, however, none of them could adjust the long-latency reflex appropriately. 3. It is concluded that central, evaluative processes commencing at the time of a perturbation cannot influence long-latency reflex responses to that perturbation.

Colebatch, J G; Gandevia, S C; McCloskey, D I; Potter, E K



Facilitation of reflex swallowing from the pharynx and larynx.  


To evaluate the cooperative effect of afferent signals from the pharynx and larynx on reflex swallowing, the interactive effect of afferent signals from the pharyngeal branch of the glossopharyngeal nerve (GPN-ph) and superior laryngeal nerve (SLN) was analyzed in detail in urethane-anesthetized rats. The electromyographic activity of the mylohyoid muscle was recorded as an indicator of swallowing activity. The onset latency of reflex swallowing was measured to evaluate the effects of electrical stimulation of these nerves, and found to become shorter following an increase in the GPN-ph and/or SLN stimulus frequency. During simultaneous electrical stimulation of the GPN-ph and SLN (frequency: 5-10 Hz, intensity: 30 muA, duration: 1.0 ms for each), the onset latency of reflex swallowing became shorter than that for stimulation of each nerve independently. The present findings suggest that spatiotemporal summation of afferent signals from the GPN-ph and SLN results in an increase of motoneuronal activity in the medullary swallowing center, thus enhancing reflex swallowing. PMID:19550082

Kitagawa, Junichi; Nakagawa, Kazuharu; Hasegawa, Momoko; Iwakami, Tomoyo; Shingai, Tomio; Yamada, Yoshiaki; Iwata, Koichi



Reflex Movements for a Virtual Human: A Biology Inspired Approach  

Microsoft Academic Search

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

Mario Gutiérrez; Frédéric Vexo; Daniel Thalmann



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



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




Microsoft Academic Search





Protective role of the hypothalamus against pathological cardiac reflexes  

Microsoft Academic Search

It is well known that the higher levels of the brain exert modulating influences on cardiac reflexes (4, 8, 11-17). However, the character of these influences has not been ex- plained, Most workers consider that they are entirely inhibitory. The possibility of facil- itatory modulating influences on the cardiac component of baroreflexes has received occasion- al mention in the literature

G. E. Samonina



Reflex sympathetic dystrophy/complex regional pain syndrome.  


Occupational health nurses are usually the first to assess workers with reflex sympathetic dystrophy/complex regional pain syndrome. Therefore, they must be aware of the signs and symptoms, implications for lost time, and higher incidence of disability related to this disorder. PMID:18306652

Gann, Charlotte



Hand muscle reflexes following electrical stimulation in choreatic movement disorders.  

PubMed Central

Thenar reflexes following electrical stimulation of the median nerve (containing proprioceptive and cutaneous afferents) and the radial superficial nerve (cutaneous afferents only) were investigated in 23 patients with manifest Huntington's disease (HD) at an early stage, in 17 clinically healthy descendants of HD-patients and in 18 patients with choreatic hyperkinesia due to various aetiologies other than HD. In 61% of the patients with early HD the long-latency reflexes (LLR) were uni- or bilaterally absent in response to both median nerve and radial superficial nerve stimulation. The remaining patients had a diminished mean amplitude and mean duration of their LLR. In contrast, offspring and patients with symptomatic chorea had preserved LLR which did not differ in amplitude or duration from normal controls. Additionally, the mean amplitude and mean duration of the Hoffmaan-reflex (HR) was found to be increased in patients with HD and their offspring but not in patients with other aetiologies. It is concluded (1) that the loss of LLR is not related to the choreatic hyperkinesia itself but to the degeneration of a hitherto poorly defined neuronal circuit in HD; (2) that among a variety of diseases presenting with chorea, the loss of LLR seems to be specific for HD; (3) that the testing of hand muscle reflexes in choreatic movement disorders is helpful for the differential diagnosis of early HD but not for the detection of gene carriers among offspring of patients with HD.

Deuschl, G; Lucking, C H; Schenck, E



Analysis of reflex modulation with a biologically realistic neural network  

Microsoft Academic Search

In this study, a neuromusculoskeletal model was built to give insight into the mechanisms behind the modulation of reflexive feedback strength as exper- imentally identified in the human shoulder joint. The model is an integration of a biologically realistic neural network consisting of motoneurons and interneurons, modeling 12 populations of spinal neurons, and a one degree-of-freedom musculoskeletal model, including proprioceptors.

Arno H. A. Stienen; Alfred C. Schouten; Jasper Schuurmans; Frans C. T. Van Der Helm



Capturing reflexivity modes in IS: A critical realist approach  

Microsoft Academic Search

Critical realism is a subject of growing interest in the IS literature. This article aims at implementing a critical realist framework: Archer [Archer, M. (2003). Structure, agency and the internal conversation. Cambridge: Cambridge University Press] internal conversation theory. As a contemporary sociologist, Archer suggests both a general vision of social practice and a typology of reflexivity modes. Her multilayered framework

François-Xavier de Vaujany



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.



On Becoming a Qualitative Researcher: The Value of Reflexivity  

ERIC Educational Resources Information Center

|Learning how to conduct qualitative research may seem daunting for those new to the task, especially given the paradigm's emphasis on complexity and emergent design. Although there are guidelines in the literature, each project is unique and ultimately the individual researcher must determine how best to proceed. Reflexivity is thus considered…

Watt, Diane




Microsoft Academic Search

This paper presents a grasping strategy of unknown objects imitating human grasping reflex for anthropomorphic robot hands. In the proposed grasping, each joint of the thumb and the fingers is controlled independently using the contact force affecting its adjacent fingertip side link. By setting a suitable contact force, both fingertip grasping and enveloped grasping with uniform grasping force are executable.

Haruhisa Kawasaki; Tetsuya Mouri; Jun Takai; Satoshi Ito



The acoustic blink reflex: Stimulus dependence, excitability and localizing value  

Microsoft Academic Search

The acoustic blink reflex was examined in 26 subjects with open eyes and 20 subjects with closed eyes by means of an electrooculogram. Amplitude and excitability are highly dependent on the loudness of the stimulus used and on the opening or closure of the eyelids. Particularly if the eyes are closed, it may be necessary to use a stimulus of

W. Sfiring; D. von Cramon



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



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



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


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



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


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

Lapole, Thomas; Canon, Francis; Pérot, Chantal



The effects of isometric resistance training on stretch reflex induced tremor in the knee extensor muscles.  


This study examines the effect of 4 wk of high-intensity isometric resistance training on induced tremor in knee extensor muscles. Fourteen healthy volunteers were assigned to either the training group (n = 7) or the nontraining control group (n = 7). Induced tremor was assessed by measuring force fluctuations during anisometric contractions against spring loading, whose compliance was varied to allow for preferential activation of the short or long latency stretch reflex components. Effects of high-intensity isometric resistance training on induced tremor was assessed under two contraction conditions: relative force matching, where the relative level of activity was equal for both pre- and post-training sessions, set at 30% maximum voluntary contraction (MVC), and absolute force matching, where the level of activity was set to 30% pretrained MVC. The training group experienced a 26.5% increase in MVC in contrast to the 0.8% for the control group. For relative force-matching contractions, induced tremor amplitude and frequency did not change in either the training or control group. During absolute force-matching contractions, induced tremor amplitude was decreased by 37.5% and 31.6% for the short and long components, respectively, with no accompanying change in frequency, for the training group. No change in either measure was observed in the control group for absolute force-matching contractions. The results are consistent with high-intensity isometric resistance training induced neural changes leading to increased strength, coupled with realignment of stretch reflex automatic gain compensation to the new maximal force output. Also, previous reported reductions in anisometric tremor following strength training may partly be due to changed stretch reflex behavior. PMID:23580599

Durbaba, Rade; Cassidy, Angela; Budini, Francesco; Macaluso, Andrea



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



Inhibitory effects from various types of dorsal column and raphe magnus stimulations on nociceptive withdrawal flexion reflexes.  


Most of the clinical and research reports agree about the analgesic effects of dorsal column (DC) stimulation, but there is no unanimity about the neural mechanisms involved in this stimulation. The aim of the present study was to compare the effects of segmental and rostral activation of the DCs and to investigate whether these effects are mediated through a brainstem spinal loop. Decerebrate-decerebellate cats were subjected to selective DC lesions at C(1) and C(3) spinal cervical levels and their reflex reactions to natural or electrical nociceptive stimuli were monitored either as withdrawal flexion reflexes or as motorneuronal discharges. Conditioning stimulation was performed as train of shocks (100 Hz, for 1 to 10 min or 300 Hz for 30 ms) applied on the DCs either rostral (DCr) or caudal (DCc) to the spinal lesions or on the raphe magnus (RM). Conditioning trains for 5-10 min applied on DCr inhibited the withdrawal flexion reflexes recorded as toe flexion (90% of the control). Comparisons of the effects of DCr, DCc or RM of conditioning stimuli were made on the discharges of 110 motorneurons recorded in isolated ventral root fibers. Conditioning stimulation applied to DCc produced short lived inhibition (in about 60%) or facilitation (in about 30% of the neurons) while DCr or RM conditioning produced inhibition in 90% of neurons which outlasted the duration of the conditioning trains. It was also shown that repetitive application of conditioning train on either DCr or RM resulted in longer duration of inhibition than that observed following DCc conditioning. We conclude that the stronger inhibition of motorneuronal discharges, evoked by nociceptive stimuli, is obtained by rostral activation of the DCs and that long term effects of DCst are mediated through a DC-brainstem-spinal loop. PMID:10536215

Saadé, N E; Atweh, S F; Privat, A; Jabbur, S J



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



A reflexive neural network for dynamic biped walking control.  


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

Geng, Tao; Porr, Bernd; Wörgötter, Florentin



Reflex regulation of airway sympathetic nerves in guinea-pigs  

PubMed Central

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

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



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


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



Ventilation and the oculocardiac reflex. Prevention of oculocardiac reflex during surgery for squints: role of controlled ventilation and anticholinergic drugs.  


A randomised prospective study was carried out in children undergoing surgery for squint correction, to determine the value of controlled ventilation as a prophylaxis against the occurrence of the oculocardiac reflex. One hundred patients anaesthetised with nitrous oxide/oxygen and halothane were randomly assigned to either ventilated or spontaneously breathing groups of 50 each. Half the patients in each group received glycopyrronium 7.5 micrograms/kg intravenously at the time of induction of anaesthesia. Heart rate, rhythm, blood pressure and end tidal CO2 concentration were monitored throughout. A positive oculocardiac reflex, defined as a fall in heart rate of 20% or more and/or the occurrence of dysrhythmias, was observed in 72% of spontaneously breathing patients and in 100% of ventilated patients not receiving prophylactic intravenous glycopyrronium. The incidence of a positive reflex in patients receiving glycopyrronium was 10% (4 and 16% respectively in spontaneously breathing and ventilated patients). It is concluded that controlled ventilation is of no value as a preventive measure against the occurrence of the oculocardiac reflex in patients undergoing squint surgery and that prophylaxis is safely achieved with the use of intravenous glycopyrronium. PMID:3752464

Mirakhur, R K; Shepherd, W F; Jones, C J



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


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

Mu, Laiyong; Ritzmann, Roy E



Changes in excitability of the flexor carpi radialis H-reflex following tactile stimulation of the index fingertip.  


Adequate stimulation of cutaneous afferents from the fingertip evokes a short-latency inhibition followed by a long-lasting excitation in human flexor carpi radialis (FCR) motoneurones. Changes in excitability of flexor motoneurones were investigated in 11 subjects by means of the H-reflex conditioning technique. The index fingertip, immobilised on a flat table, was stimulated by a small probe mounted on an electromagnetic vibrator. Contact time and tactile perception threshold (PT) were monitored throughout the experiment. In all subjects, tactile stimulation of the skin covering the index pulp, with 10 ms long square pulses, at an intensity of 2-2.5 PT, produced an inhibition starting at a conditioning-test interval of 15 ms and lasting about 2 ms. This was followed by a powerful facilitation lasting more than 10 ms. Excitation appeared just at tactile threshold, whereas threshold for inhibition was about 2 PT. Similar effects were observed after mechanical stimulation of the skin covering the dorsal aspect of the index, close to the nail. Local anaesthesia of the finger pulp drastically reduced both the inhibition and the facilitation of FCR H-reflex. By contrast, electrical stimulation of the index digital nerves, by means of ring electrodes, was always ineffective in modifying the excitability of the FCR H-reflex. It is proposed that inhibition and excitation of FCR H-reflex are caused by activation of oligosynaptic pathways fed by cutaneous afferents; however, it cannot be excluded that joint receptors and primary endings of small hand muscles may contribute in part to the late excitation. The pathways described might play an essential role in modulation and control of exploratory movements and object manipulation, actions that need tactile information to regulate muscle force. PMID:9628421

Cavallari, P; Lalli, S



Novel cross correlation technique allows crosstalk resistant reflex detection from surface EMG.  


Existing methods for withdrawal reflex detection from surface electromyography (sEMG) do not consider the potential presence of electrical crosstalk, which in practical applications may entail reduced detection accuracy. This study estimated muscle fiber conduction velocities (CV) for the tibialis anterior (TA) and soleus (SOL) muscles of both genuine reflexes and identified crosstalk, measured during antagonistic reflex responses. These estimations were used to develop and assess a novel method for reflex detection resistant to crosstalk. Cross correlations of two single differential (SD) sEMG signals recorded along the muscle fibers were performed and two features were extracted from the resulting correlograms (average CV and maximal cross correlation). Reflex detection based on evaluation of the extracted features was compared to a conventional reflex detection method (thresholding of interval peak z-scores), applied on both SD and double differential (DD) sEMG. Intramuscular electromyography (iEMG) was used as validation for reflex detection. Apparent CV due to electrical crosstalk alone were more than one order of magnitude higher than CV estimated for genuine reflexes. Conventional reflex detection showed excellent sensitivity but poor specificity (0.19-0.76) due to the presence of crosstalk. In contrast, cross correlation analysis allowed reflex detection with significantly improved specificity (0.91-0.97). The developed methodology may be readily implemented for more reliable reflex detection. PMID:23366689

Jensen, Michael B; Frahm, Ken Steffen; Biurrun Manresa, Jose; Andersen, Ole K



Effect of sympathetic nervous system activation on the tonic vibration reflex in rabbit jaw closing muscles.  

PubMed Central

1. In precollicular decerebrate rabbits we investigated the effect of sympathetic stimulation, at frequencies within the physiological range, on the tonic vibration reflex (TVR) elicited in jaw closing muscles by small amplitude vibrations applied to the mandible (15-50 microns, 150-180 Hz). The EMG activity was recorded bilaterally from masseter muscle and the force developed by the reflex was measured through an isometric transducer connected with the mandibular symphysis. 2. Unilateral stimulation of the peripheral stump of the cervical sympathetic by the TVR, and a marked decrease or disappearance of the ipsilateral EMG activity. No significant changes were detected in the EMG contralateral to the stimulated nerve. Bilateral CSN stimulation reduced by 60-90% the force reflexly produced by the jaw closing muscles and strongly decreased or suppressed EMG activity on both sides. This effect was often preceded by a transient TVR enhancement, very variable in amplitude and duration, which was concomitant with the modest increase in pulmonary ventilation induced by the sympathetic stimulation. 3. During bilateral CSN stimulation, an increase in the vibration amplitude by a factor of 1.5-2.5 was sufficient to restore the TVR reduced by sympathetic stimulation. 4. The depressant action exerted by sympathetic activation on the TVR is mediated by alpha-adrenergic receptors, since it was almost completely abolished by the I.V. administration of either phentolamine or prazosin, this last drug being a selective antagonist of alpha 1-adrenoceptors. The sympathetically induced decrease in the TVR was not mimicked by manoeuvres producing a large and sudden reduction or abolition of the blood flow to jaw muscles, such as unilateral or bilateral occlusion of the common carotid artery. 5. The effect of sympathetic stimulation was not significantly modified after denervation of the inferior dental arch and/or anaesthesia of the temporomandibular joint, i.e. after having reduced the afferent input from those receptors, potentially affected by CSN stimulation, which can elicit either a jaw opening reflex or a decrease in the activity of the jaw elevator muscle motoneurons. 6. These data suggest that, when the sympathetic nervous system is activated under physiological conditions, there is a marked depression of the stretch reflex which is independent of vasomotor changes and is probably due to a decrease in sensitivity of muscle spindle afferents.

Grassi, C; Deriu, F; Passatore, M



Classical conditioned responses to absent tones  

Microsoft Academic Search

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

Marc Bangert; Uwe Jürgens; Udo Häusler; Eckart Altenmüller



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

PubMed Central

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

Iles, J F; Pisini, J V



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



Reflex bradycardia induced by hydralazine in sino-aortic deafferented conscious rats.  


1. It is generally recognized that the vasodilator hydralazine produces hypotension accompanied by baroreflex-mediated tachycardia. In some experimental conditions, however, the accompanying heart rate change is bradycardia, a paradoxical response which has not been satisfactorily explained. The present study examined the possibility of hydralazine-induced bradycardia being mediated by vagal or sympathetic afferents activated by changes in left ventricular pressure. 2. Systolic blood pressure and heart rate responses to hydralazine were recorded in conscious normotensive intact rats by a tail cuff method and compared with responses in animals subjected to previous sino-aortic deafferentation (SAD) to remove the influence of the arterial baroreflex. Responses were also obtained after blockade of myocardial afferent vagal C-fibres with urethane, of efferent vagal impulses to the heart with methylatropine, of positive inotropic effects of hydralazine with atenolol, and of prostanoid sensitization of myocardial nerve fibres with indomethacin. 3. Hydralazine produced hypotension and tachycardia in intact rats, and hypotension and bradycardia in SAD animals. In intact rats, this pattern was not affected by any of the pretreatments, while in SAD rats, all pretreatments reversed the bradycardia to hydralazine. 4. The present results indicate that suppression of the arterial baroreflex by SAD propitiates the appearance of a bradycardiac response to hydralazine. This reaction probably results from activation of a vagal cardiodepressant reflex originating in the heart, as suggested by its blockade by drugs acting at various sites along the reflex arch. PMID:14565540

Sánchez-Salvatori, M A; Vidrio, H



Habituation and sensitization of protective reflexes: dissociation between cardiac defense and eye-blink startle.  


We examined the habituation and recovery of two protective reflexes, cardiac defense and eye-blink startle, simultaneously elicited by a white noise of 500ms as a function of the time interval between stimulus presentations. Participants were 90 volunteers (54 women) randomly distributed into 6 inter-trial interval (ITI) conditions. They all received three presentations of the stimulus with a time interval of 30min between the first and third noise. The timing of the second noise was manipulated in six steps, using a between-group design, in order to increase the ITI between Trials 1 and 2 and symmetrically decrease the ITI between Trials 2 and 3. Cardiac defense showed fast habituation at the shortest ITI (2.5min), but reduced habituation and increased recovery at the longest ITI (27.5min). In contrast, eye-blink startle showed sensitization irrespective of the ITI. This pattern of findings highlights dissociations between protective reflexes when simultaneously examined. The results are discussed in the context of the cascade model of defense reactions. PMID:19397949

Mata, José Luís; Rodríguez-Ruiz, Sonia; Ruiz-Padial, Elisabeth; Turpin, Graham; Vila, Jaime



Early Modern ET, Reflexive Telescopics, and Their Relevance Today  

NASA Astrophysics Data System (ADS)

The period from the discovery of Tycho's New Star in 1572 to Galileo's "geometrization of astronomical space" in 1610 (and the years following) saw the disintegration of the boundary between the sublunary and superlunary spheres—between the "lower storey" and "upper storey" of the Aristotelian Universe. This establishment of a strong physical affinity between the universe "up there" and the earthly realm "down here" was also complemented by the rise of Copernicanism: for once the Earth was seen as a planet, the other planets could readily be imagined as other Earths. This analogy suggested not only physical but also biological affinities and supported the plausibility of humans' capacity to travel to the Moon and beyond. Robert Burton—given the demise of Aristotle's physics—declared in 1621 that "If the heavens be penetrable … it were not amiss in this aerial progress to make wings and fly up." John Wilkins and Francis Godwin in the 1630s actively imagined creatures in the Moon and human journeys thither. The epic poet John Milton in 1667 hinted that "every star [is] perhaps a world / Of destined habitation." Moreover, space travel was no one-way street: Thomas Traherne in the 1670s imagined a dweller among the stars visiting Earth and remarking on what must be the condition of its inhabitants. In these and other ways, seventeenth-century writers offered serious and impressive speculation about extraterrestrial life and its possible perceptions of Earth. Such speculations remain pertinent to astrobiological theory today. What Hans Blumenberg in the 1970s called "reflexive telescopics"—the examination of Earth from an imagined extraterrestrial viewpoint—is an important counterpart to the search for life "out there." It serves as a reminder of the obvious but profound premise that Earth is part of the cosmos. At a popular level we often continue to speak of "outer space" as if the old "two-storey" picture of the universe still had some residual legitimacy. However, if Galileo, Wilkins, and other devotees of the New Astronomy were right about Earth's being a full participant in "the dance of the stars," then "outer" is a merely relative and parochial term, not a scientific or qualitative one. And it is no trivial claim to assert that the search for intelligent life in the universe has already identified its first specimens.

Danielson, Dennis


Peripheral axotomy increases the expression of galanin message-associated peptide (GMAP) in dorsal root ganglion cells and alters the effects of intrathecal GMAP on the flexor reflex in the rat.  


We have previously reported that galanin message-associated peptide (GMAP), a fragment of galanin precursor protein, occurs in a limited number of dorsal root ganglion (DRG) cells in rats with intact sciatic nerves. In the present study, the localization of GMAP in dorsal root ganglia, dorsal roots and dorsal horn was analyzed immunohistochemically and compared between rats with intact and sectioned sciatic nerves. Furthermore, the effects of intrathecal (i.t.) GMAP on the flexor reflex in rats with intact and sectioned nerves were examined. In rats with intact sciatic nerves, i.t. GMAP elicited a moderate facilitation of the flexor reflex. The facilitation of the flexor reflex induced by conditioning stimulation (CS) of cutaneous C-fibers was strongly blocked by GMAP. GMAP also selectively antagonized the reflex facilitatory effect of i.t. substance P (SP), but not i.t. vasoactive intestinal peptide (VIP). Unilateral sciatic nerve section induced an upregulation of GMAP in the ipsilateral dorsal root ganglia 2 weeks after axotomy. The effect of GMAP on the baseline reflex was similar in normal and axotomized rats, but the blocking effect of GMAP on C-fiber CS-induced facilitation was significantly reduced after axotomy. GMAP did not antagonize the reflex facilitatory effect of SP after axotomy, whereas an antagonism on VIP-induced facilitation was observed. The possible role of GMAP in spinal transmission and comparison with the effects of galanin are discussed. PMID:7603589

Xu, X J; Andell, S; Zhang, X; Wiesenfeld-Hallin, Z; Langel, U; Bedecs, K; Hökfelt, T; Bartfai, T



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


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

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



The afferent volleys responsible for spinal proprioceptive reflexes in man  

PubMed Central

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

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



A model of reflex tracheal constriction in the dog.  


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

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



Lack of trigemino-cervical reflexes in progressive supranuclear palsy.  


Trigemino-cervical reflexes (TCRs) are multisynaptic neck muscle withdrawal responses that are clearly identifiable in humans. Mediated by neural circuits at brainstem level, these reflex responses have been found to be significantly impaired in patients with Parkinson's disease (PD), and it has been hypothesized that a degeneration of brainstem neural structures could play a role in these abnormalities. Because extensive neuronal degeneration at brainstem level has been demonstrated in progressive supranuclear palsy (PSP), in this pilot study we evaluated the TCR responses in 12 subjects with PSP, and in 16 healthy controls. The TCRs were absent in 11 out of the 12 PSP patients while clear responses were evoked in all the healthy subjects. These findings indicate that PSP patients are unable to react to the painful stimuli to the face, suggesting a generalized impairment of the brainstem circuits mediating TCRs. PMID:18561341

Bartolo, Michelangelo; Serrao, Mariano; Perrotta, Armando; Tassorelli, Cristina; Sandrini, Giorgio; Pierelli, Francesco



Kinematic and electromyographic study of the nociceptive withdrawal reflex in the upper limbs during rest and movement.  


This study set out to evaluate nociceptive withdrawal reflex (NWR) excitability and the corresponding mechanical response in the upper limbs during rest and movement. We used a three-dimensional motion analysis system and a surface EMG system to record, in 10 healthy subjects, the NWR in eight upper limb muscles and the corresponding mechanical response in two experimental conditions: rest and movement (reaching for, picking up, and moving a cylinder). The NWR was elicited through stimulation of the index finger with trains of pulses delivered at multiples of the pain threshold (PT). We correlated movement types (reach-to-grasp, grasp-and-lift), movement phases (acceleration, deceleration), and muscle activity types (shortening, lengthening, isometric) with the presence/absence of the NWR (reflex-muscle pattern), with NWR size values, and with the mechanical responses. At rest, when the stimulus was delivered at 4x PT, the NWR was present, in all muscles, in >90% of trials, and the mechanical response consisted of wrist adduction, elbow flexion, and shoulder anteflexion. At this stimulus intensity, during movement, the reflex-muscle pattern, reflex size, and mechanical responses were closely modulated by movement type and phase and by muscle activity type. We did not find, during movement, significant correlations with the level of EMG background activity. Our findings suggest that a complex functional adaptation of the spinal cord plays a role in modulating the NWR in the transition from rest to movement and during voluntary arm movement freely performed in three-dimensional space. Study of the upper limb NWR may provide a window onto the spinal neural control mechanisms operating during movement. PMID:16571758

Serrao, Mariano; Pierelli, Francesco; Don, Romildo; Ranavolo, Alberto; Cacchio, Angelo; Currà, Antonio; Sandrini, Giorgio; Frascarelli, Massimo; Santilli, Valter



Stretch sensitive reflexes as an adaptive mechanism for maintaining limb stability  

PubMed Central

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

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



Influence of body position on fibularis longus and soleus Hoffmann reflexes.  


It is widely accepted that Hoffmann (H) reflex amplitudes of the soleus decrease as complexity of body positions increases, but it is not known if this same mechanism of postural control is seen in other ankle muscles such as fibularis longus (FL). Our purpose was to assess if FL H-reflex changed in different body positions and if the adaptations were correlated to soleus H-reflex modulation. Fifteen healthy subjects had their FL and soleus H-reflexes measured in three positions (prone, bipedal, unipedal). Maximal H-reflexes (H-max) and motor responses (M-max) were collected bilaterally. The average H-max and M-max were used to calculate H(max)/M(max) ratios. To control influences of background muscle activity on H-reflex measures, the ratios were normalized to their corresponding mean EMG amplitudes over a 50-ms time epoch. H-reflex amplitudes of both muscles were significantly lower in unipedal stance than other positions. Additionally, there were strong correlations (R(2)>0.7) in H-reflex modulation between the two muscles when transitioning from prone to either bipedal or unipedal stance. Down-modulation of H-reflex when transitioning to unipedal stance was present in both FL and soleus suggesting that H-reflex modulation of both muscles may play a similar role in control of upright posture. PMID:22795783

Kim, Kyung-Min; Hart, Joseph M; Hertel, Jay



Peripheral ?-opioid receptors attenuate the exercise pressor reflex.  


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

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



Impulsive Consumption and Reflexive Thought: Nudging Ethical Consumer Behavior  

Microsoft Academic Search

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

Leonhard K. Lades



SMOS REFLEX 2003: L-band emissivity characterization of vineyards  

Microsoft Academic Search

The goal of the Soil Moisture and Ocean Salinity mission over land is to infer surface soil moisture from multiangular L-band radiometric measurements. As the canopy affects the microwave emission of land, it is necessary to characterize different vegetation layers. This paper presents the Reference Pixel L-Band Experiment (REFLEX), carried out in June-July 2003 at the Vale`ncia Anchor Station, Spain,

M. Vall-Llossera; A. Camps; I. Corbella; F. Torres; N. Duffo; A. Monerris; R. Sabia; D. Selva; C. Antolin; E. Lopez-Baeza; J. F. Ferrer; K. Saleh



Use of the bulbocavernosus reflex system in assessing voiding dysfunction.  


PURPOSE: The Bulbocavernosus Reflex System (BRS) (Laborie, Canada) is an office-based procedure used to measure the bulbocavernosus reflex (BCR) latency period. The aim of this study is to evaluate the BCR as a predictor of specific voiding dysfunction patterns confirmed by urodynamics (UDS). METHODS: A total of 87 men were evaluated with BRS, UDS, and electromyography at Weill Cornell Medical College from March to August 2010. Baseline characteristics, demographics, UDS, and latency parameters were recorded. Multivariate logistic regression analysis was performed to evaluate prolonged BCR (latency >45 ms) as a predictor of specific voiding dysfunction patterns. RESULTS: The median age of men was 70.4 years (IQR 57.6-75.6). Based on UDS, 60 men were given a primary or secondary diagnosis of bladder outlet obstruction (BOO), 43 a diagnosis of detrusor overactivity (DO), 11 a diagnosis of intrinsic sphincter deficiency (ISD), and 4 a diagnosis of detrusor sphincter dyssynergia (DSD). Median BCR latency was 57.0 ms (IQR 47.5-76.5) and 68 (78 %) men demonstrated a prolonged latency. In multivariate analysis, latency period was not significantly associated with DO, BOO, ISD, or DSD (p = 0.067, 0.696, 0.999, 0.971, respectively). CONCLUSIONS: Prolonged bulbocavernosus reflex latency was not associated with DO, BOO, ISD, or DSD. Although evidence in the literature suggests a link between this reflex arc and voiding, its specific diagnostic role remains unclear. Large prospective trials are needed to further explore the role of BCR in the evaluation of patients with voiding dysfunction. PMID:23525787

Laudano, Melissa A; Chughtai, Bilal; Lee, Richard K; Seklehner, Stephan; Elterman, Dean; Kaplan, Steven A; Te, Alexis E



The effect of mindfulness meditation on cough reflex sensitivity  

Microsoft Academic Search

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

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



Cephalic phase, reflex insulin secretion neuroanatomical and physiological characterization  

Microsoft Academic Search

Summary  Using chronically catheterized, freely moving male Wistar rats, we have shown that the sweet taste of a saccharin solution\\u000a reliably triggers a rapid cephalic phase insulin response (CPIR), in the absence of any significant change of glycemia. To\\u000a establish the neural mediation of this reflex response we used rats that were cured from streptozotocin diabetes by intrahepatic\\u000a islet-transplantation as a

H. R. Berthoud; D. A. Bereiter; E. R. Trimble; E. G. Siegel; B. Jeanrenaud



Airway Receptors and Their Reflex Function – Invited Article  

Microsoft Academic Search

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

J. Yu


Complex regional pain syndromes—reflex sympathetic dystrophy and causalgia  

Microsoft Academic Search

Reflex sympathetic dystrophy (RSD) was the term applied to a variety of unrelated disorders having strikingly similar clinical\\u000a features.The problem with the term RSD is that not all cases meet the classical case scenario.The umbrella term Complex Regional\\u000a Pain Syndromes (CRPS) now includes causalgia and RSD and excludes sympathetically mediated pain, neuropathic pain, inflammatory\\u000a pain, and phantom pain. Complex Regional

P. Prithvi Raj



Neuroadrenergic and reflex abnormalities in patients with metabolic syndrome  

Microsoft Academic Search

Aims\\/hypothesis  Previous studies have shown that alterations in vascular, metabolic, inflammatory and haemocoagulative functions characterise the metabolic syndrome. Whether this is also the case for sympathetic function is not clear. We therefore aimed to clarify this issue and to determine whether metabolic or reflex mechanisms might be responsible for the possible adrenergic dysfunction.Methods  In 43 healthy control subjects (age 48.2±1.0 years, mean±SEM)

G. Grassi; R. Dell’Oro; F. Quarti-Trevano; F. Scopelliti; G. Seravalle; F. Paleari; P. L. Gamba; G. Mancia



Soleus H-reflex excitability during pedaling post-stroke  

Microsoft Academic Search

A major contributor to impaired locomotion post-stroke is abnormal phasing of paretic muscle activity, but the mechanisms\\u000a remain unclear. Previous studies have shown that, in the paretic limb of people post-stroke, Group Ia reflexes are abnormally\\u000a elevated and fail to decrease in amplitude during locomotion. Hence, we hypothesized that inappropriate muscle phasing may\\u000a be associated with enhanced transmission in the

Sheila Schindler-Ivens; David A. Brown; Gwyn N. Lewis; Jens Bo Nielsen; Kathy L. Ondishko; Jon Wieser



Flexion reflex modulation during stepping in human spinal cord injury  

Microsoft Academic Search

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

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



Reflex gain of muscle spindle pathways during fatigue  

Microsoft Academic Search

There are conflicting observations of the effects of fatigue on the sensitivity of large diameter Ia afferents. Our goal was\\u000a to characterize any fatigue-related changes in the spinal reflex pathways during fatigue. Manipulation of the Ia afferent\\u000a response by vibration and tendon tap, in which the motor neuron pool is modulated by both short- and long-loop activation\\u000a from muscle spindles,

A. Biro; L. Griffin; E. Cafarelli



Spinal reflexes in the long-tailed stingray, Himantura fai  

Microsoft Academic Search

We have exploited the segregation of motor and sensory axons into peripheral nerve sub-compartments to examine spinal reflex\\u000a interactions in anaesthetized stingrays. Single, supra-maximal electrical stimuli delivered to segmental sensory nerves elicited\\u000a compound action potentials in the motor nerves of the stimulated segment and in rostral and caudal segmental motor nerves.\\u000a Compound action potentials elicited in segmental motor nerves by

Peter D. Kitchener; Peter J. Snow



Absent stapedial reflex: otosclerosis or middle ear tumor?  


We present an unusual case in which a patient diagnosed as having otosclerosis on the basis of clinical and audiologic findings actually had a middle ear facial nerve schwannoma. To the best of our knowledge, this is the first reported case in English literature in which a facial nerve schwannoma presented with conductive deafness of gradual onset and absent stapedial reflex with a normally functioning facial nerve. We also include a review of the literature. PMID:23460218

Biswas, Deb; Mal, Ranjit K



Modeling movement disorders--CRPS-related dystonia explained by abnormal proprioceptive reflexes.  


Humans control their movements using adaptive proprioceptive feedback from muscle afferents. The interaction between proprioceptive reflexes and biomechanical properties of the limb is essential in understanding the etiology of movement disorders. A non-linear neuromuscular model of the wrist incorporating muscle dynamics and neural control was developed to test hypotheses on fixed dystonia. Dystonia entails sustained muscle contractions resulting in abnormal postures. Lack of inhibition is often hypothesized to result in hyperreflexia (exaggerated reflexes), which may cause fixed dystonia. In this study the model-simulated behavior in case of several abnormal reflex settings was compared to the clinical features of dystonia: abnormal posture, sustained muscle contraction, increased stiffness, diminished voluntary control and activity-aggravation. The simulation results were rated to criteria based on characteristic features of dystonia. Three abnormal reflex scenarios were tested: (1) increased reflex sensitivity-increased sensitivity of both the agonistic and antagonistic reflex pathways; (2) imbalanced reflex offset-a static offset to the reflex pathways on the agonistic side only; and (3) imbalanced reflex sensitivity-increased sensitivity of only the agonistic reflex pathways. Increased reflex sensitivity did not fully account for the features of dystonia, despite distinct motor dysfunction, since no abnormal postures occurred. Although imbalanced reflex offset did result in an abnormal posture, it could not satisfy other criteria. Nevertheless, imbalanced reflex sensitivity with unstable force feedback in one of the antagonists closely resembled all features of dystonia. The developed neuromuscular model is an effective tool to test hypotheses on the underlying pathophysiology of movement disorders. PMID:22112920

Mugge, Winfred; Munts, Alexander G; Schouten, Alfred C; van der Helm, Frans C T



Sweet taste and menthol increase cough reflex thresholds.  


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

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



Area postrema-induced inhibition of the exercise pressor reflex.  


The exercise pressor reflex is opposed by the arterial baroreflex, and circulating peptides may act in the area postrema to enhance this inhibition. Therefore, we tested the hypothesis that the area postrema exerts an inhibitory effect on this reflex. Consequently, in six alpha-chloralose-anesthetized cats, blood pressure and heart rate responses to 30 s of electrically stimulated hindlimb contraction were compared before and after thermal coagulation of the area postrema. In six other cats, the same contraction-induced cardiovascular responses were assessed before and after chemical lesion of the area postrema using kainic acid (214 +/- 9 nl, 2.5-5 mM). Thermal lesion of the area postrema augmented blood pressure and heart rate responses to contraction from 29 +/- 5 to 47 +/- 7 mmHg (P < 0.05) and from 8 +/- 2 to 14 +/- 2 beats/min (P < 0.05), respectively. Chemical lesion of the area postrema enhanced contraction-evoked blood pressure (30 +/- 7 vs. 47 +/- 6 mmHg, P < 0.05) and heart rate (12 +/- 4 vs. 17 +/- 4 beats/min, P < 0.05) responses. These data suggest that the area postrema attenuates the exercise pressor reflex, possibly through the actions of circulating peptides on baroreflex function. PMID:9139947

Bonigut, S; Bonham, A C; Stebbins, C L



Dynamic spindle reflexes and the rigidity of Parkinsonism  

PubMed Central

The effects of stimulating the reflex arc from dynamic spindle endings were examined in patients with the rigidity of Parkinsonism and in control subjects. The arc was activated phasically by a tendon tap and by electrical stimulation in 15 patients. The effect of reinforcement by Jendrassik's manoeuvre was observed. The response to phasic activation indicated central facilitation of the reflex loop in the patients with Parkinsonism, with a concurrent decrease in fusimotor drive to dynamic spindles. These abnormalities could not be correlated with the severity of the patients' rigidity, and they did not alter when the rigidity was reduced by levodopa. The effect of activating dynamic spindle endings tonically by vibration at 50 Hz was also examined. The reflex contraction of the biceps and triceps muscles in response to vibration was found to be increased in 24 patients with rigidity compared with 24 control subjects. Patients with severe rigidity developed a more powerful contraction in response to vibration than patients with mild rigidity. The response to vibration was reduced by treatment with levodopa but the amount of this reduction could not be correlated with changes in the patients' rigidity.

McLellan, D. L.



The clustering of clusters of galaxies in the REFLEX survey  

NASA Astrophysics Data System (ADS)

We summarize the major clustering results obtained so far from the REFLEX survey of X-ray clusters of galaxies. The REFLEX survey is now virtually 100% redshift complete to a flux limit 3×10-12 erg s-1 cm-2 (in the ROSAT band, 0.1-2.4 keV) and several clustering analyses are underway. The most interesting results are being obtained on the power spectrum, which has been estimated on scales approaching ~1000h-1 Mpc and whose shape and amplitude are both in very good agreement with the predictions of a low-?M (open or ?-dominated) CDM model. Both the power spectrum and the two-point correlation function show a remarkable agreement in shape - just scaled by a constant b2 ~ 7 - 10 in amplitude - with the corresponding statistics measured from galaxy surveys, confirming the validity of a simple biasing scheme. Several tests, as e.g. the behaviour of the mean cluster density as a function of redshift, or the isotropy of the correlation function ?(?p, ?), represent additional confirmation that the current REFLEX sample is highly complete (>90%) and with a well-controlled selection function.

Guzzo, L.; Böhringer, H.; Collins, C. A.; Schuecker, P.; Chincarini, G.; Cruddace, R.; de Grandi, S.; Neumann, D. M.; Schindler, S.; Shaver, P. A.; Voges, W.


Sympathetic or reflex footpad swelling due to crystal-induced inflammation in the opposite foot.  


Sympathetic or reflex footpad swelling occurred in rats when several crystals known to be pathogenic in human joints or soft tissues were injected into the opposite footpad. Monosodium urate (MSU), calcium pyrophosphate dihydrate (CaPPD), hydroxyapatite, calcium oxalate (CaOx), and xanthine (X) suspension induced varying degrees of such reflex of sympathetic swelling. In the second cycle of crystal-induced swelling, the foot that had been the initial or primary site of inflammation reacted with greater reflex swelling, when compared to the first cycle. Similarly, reflex increases in temperature occurred when CaPPD was injected. These reflex increases in swelling and temperature may relate to signs and symptoms of patients with reflex neurovascular dystrophy or shoulder--hand syndrome. PMID:680952

Denko, C W; Petricevic, M



Effect of intrathecal baclofen on the monosynaptic reflex in humans: evidence for a postsynaptic action.  

PubMed Central

Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosynaptic H-reflex in spinal patients was investigated. It could inhibit rapidly and profoundly monosynaptic reflexes in lower limbs, but did not modify Ia vibratory inhibition of the soleus H-reflex. To assess more precisely its effect on Ia afferents, an experimental paradigm using Ia heteronymous facilitation of the soleus H-reflex was used. Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve. This demonstrates that the main part of the inhibitory effect of baclofen on the H-reflex in spinal patients is not due to a presynaptic effect, suggesting a postsynaptic site of action.

Azouvi, P; Roby-Brami, A; Biraben, A; Thiebaut, J B; Thurel, C; Bussel, B



Impact of scratching on itch and sympathetic reflexes induced by cowhage (Mucuna pruriens) and histamine.  


Cowhage and histamine, both applied via spicules, were used to induce itch. The quality and intensity of the sensations, axon reflex flare, sympathetic skin vasoconstrictions and the interference of scratching with itch processing were studied. Axon reflex flare reactions were measured by laser Doppler imaging and reflex vasoconstrictions in the finger were recorded by laser Doppler flowmetry. Magnitude of itch sensations was assessed on an electronic visual analogue scale while the skin was intermittently scratched proximal to the application site. The quality of itch was assessed with a questionnaire. Only histamine produced an axon reflex flare. Histamine itch increased faster, but recovered more slowly after scratching, by which it was more effectively suppressed. Cowhage induced a sharper itch sensation and stronger vasoconstrictor reflexes. These findings support the notion that both agents activate different pathways. The differences in sympathetic reflex induction and in the modulation by scratching indicate differential central nervous processing. PMID:19479124

Kosteletzky, Frauke; Namer, Barbara; Forster, Clemens; Handwerker, Herman O



Low-frequency H-reflex depression in trained human soleus after spinal cord injury  

Microsoft Academic Search

After spinal cord injury (SCI), widespread reorganization occurs within spinal reflex systems. Regular muscle activity may influence reorganization of spinal circuitry after SCI. The purpose of this study is to investigate the effects of long-term soleus training on H-reflex depression in humans after SCI. Seven subjects with acute (<7 weeks) SCI (AC group) underwent testing of H-reflex depression at several

Richard K. Shields; Shauna Dudley-Javoroski; Preeti Deshpande Oza



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


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

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



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



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



Reflexes elicited from cutaneous and mucosal trigeminal afferents in normal human subjects  

Microsoft Academic Search

It has been shown that in patients in whom the central stump of the hypoglossal nerve has been anastomosed to the peripheral stump of a lesioned facial nerve, supraorbital nerve stimulation can elicit a short-latency reflex (12.5±0.6 ms; mean±S.D.) in facial muscles similar to the R1 disynaptic blink reflex response, but not followed by an R2 blink reflex component46. Thus

Thierry Maisonobe; Frédéric Tankéré; Georges Lamas; Jacques Soudant; Pierre Bouche; Jean Claude Willer; Emmanuel Fournier



Abnormalities of the acoustic startle reflex and reaction time in Gilles de la Tourette syndrome  

Microsoft Academic Search

Objective: To study the startle reflex and the effect of the startle reflex stimulus over reaction time (start-react effect) in Gilles de la Tourette syndrome (GTS).Method: Ten GTS patients and ten matched healthy volunteers underwent a simple RT paradigm (4 blocks of 50 trials). Forty acoustic startle reflex stimuli (110 dB) were randomly delivered with a 20% occurrence probability and

A. Gironell; A Rodr??guez-Fornells; J Kulisevsky; B Pascual; J Riba; M. Berthier



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

Microsoft Academic Search

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.\\u000a The ASD group, however, showed anomalous reflex modulation patterns, despite similar self-report ratings of pictures. Specifically,\\u000a the ASD group demonstrated exaggerated eyeblink responses to pleasant images and exaggerated postauricular responses

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



Self-Representation in Severe Psychopathology: The Role of Reflexive Self-Awareness  

Microsoft Academic Search

In both normal and abnormal functioning, the self is a complex psychological structure that is constituted and experientially divided by reflexive self-awareness—by the tension that arises from coordinating subjective and objective perspectives on the self. Disturbances in reflexive self-awareness are central to the development of severe psychopathology. Although both schizophrenia and borderline personality disturbances involve difficulties in self-reflexivity, schizophrenia also

John S. Auerbach; Sidney J. Blatt



Post-activation depression of Soleus stretch reflexes in healthy and spastic humans  

Microsoft Academic Search

Reduced depression of transmitter release from Ia afferents following previous activation (post-activation depression) has\\u000a been suggested to be involved in the pathophysiology of spasticity. However, the effect of this mechanism on the myotatic\\u000a reflex and its possible contribution to increased reflex excitability in spastic participants has not been tested. To investigate\\u000a these effects, we examined post-activation depression in Soleus H-reflex

Michael J. Grey; Klaus Klinge; Clarissa Crone; Jakob Lorentzen; Fin Biering-Sørensen; Mads Ravnborg; Jens B. Nielsen



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

Microsoft Academic Search

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

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



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

Microsoft Academic Search

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

Sandra R. Hundza; E. Paul Zehr



Assessment of Deep Tendon Reflexes by Motion Analysis: A Preliminary Study  

Microsoft Academic Search

\\u000a The deep tendon reflex responses are judged by clinicians through visual observation with great variations between different\\u000a examiners leading to high possibilities of errors. This study proposed an alternative approach to quantify the deep tendon\\u000a reflex responses. In the preliminary stage, the motion analysis system was used to collect quantitative data for patellar\\u000a tendon reflex, one of the deep tendon

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


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

PubMed Central

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

Holmberg, H; Schouenborg, J



Enhanced stretch reflex excitability of the soleus muscle in experienced swimmers  

Microsoft Academic Search

The purpose of this study was to investigate effects of long-term participation to swimming on adaptations of spinal reflex\\u000a excitability. To this end, mechanically induced stretch reflex (SR) and electrically induced Hoffmann (H-) reflex of the soleus\\u000a muscle were investigated between swimmers with experience of more than 10 years and non-trained individuals while sitting\\u000a at rest. The amplitude and the gain

Tetsuya Ogawa; Gee Hee Kim; Hirofumi Sekiguchi; Masami Akai; Shuji Suzuki; Kimitaka Nakazawa



"The Sphinx must solve her own riddle": Emerson, secrecy, and the self-reflexive method.  


This article offers a fresh approach to the religious thought of Ralph Waldo Emerson, exploring (1) the particular conception of secrecy in connection with which he understands the human spiritual predicament and (2) his response to this predicament by means of a self-reflexive turn in his writing-a procedure designed to undermine quests for truth elsewhere and so to restore the self to the wholeness implicit in its initial conditions. The operation of this method will be traced through a number of Emerson's major works, including the second "Nature" (from Essays: Second Series), "History," and the poem "The Sphinx." Along the way, Emerson's thought will be discussed in relation to the history of Emerson criticism, alternative views of secrecy in religion, and the theory and practice of religious nondualism, to which Emerson's intellectual project bears considerable resemblance. PMID:20681101

Smith, David L



Event-related EEG time-frequency analysis and the Orienting Reflex to auditory stimuli.  


Sokolov's classic works discussed electroencephalogram (EEG) alpha desynchronization as a measure of the Orienting Reflex (OR). Early studies confirmed that this reduced with repeated auditory stimulation, but without reliable stimulus-significance effects. We presented an auditory habituation series with counterbalanced indifferent and significant (counting) instructions. Time-frequency analysis of electrooculogram (EOG)-corrected EEG was used to explore prestimulus levels and the timing and amplitude of event-related increases and decreases in 4 classic EEG bands. Decrement over trials and response recovery were substantial for the transient increase (in delta, theta, and alpha) and subsequent desynchronization (in theta, alpha, and beta). There was little evidence of dishabituation and few effects of counting. Expected effects in stimulus-induced alpha desynchronization were confirmed. Two EEG response patterns over trials and conditions, distinct from the full OR pattern, warrant further research. PMID:22524168

Barry, Robert J; Steiner, Genevieve Z; De Blasio, Frances M



Suppression of the nociceptive jaw-opening reflex by stimulation of the red nucleus.  


We studied the effect of stimulation of the red nucleus (RN) on the jaw-opening reflex (JOR) in anesthetized rats. The JOR was evoked by electrical stimulation of the tooth pulp of a lower incisor, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the RN was found to suppress the JOR bilaterally. Microinjection of monosodium glutamate into the RN also suppressed the JOR bilaterally. The suppressive effect of the magnocellular part of the RN was significantly larger than that of the parvicellular part of the RN. These results imply that the RN is involved in control of the JOR evoked by noxious stimulus. PMID:22877853

Yajima, Eriko; Satoh, Yoshihide; Ishizuka, Ken'Ichi; Iwasaki, Shin-ichi; Terada, Kazuto



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



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



Visceral and somatic reflexes produced by J pulmonary receptors in newborn kittens.  


The functional efficiency of J pulmonary receptor reflexes was studied in 28 newborn anesthetized kittens. J receptor stimulation was achieved by injecting phenyl diguanide (PDG) solution into the right atrium using a technique established earlier for cats. Control injections of PDG into the aorta were made. Respiration, aortic blood presure, and knee jerk were recorded. The Hering-Breuer reflex was routinely tested in each kitten by inflating the lungs through the tracheal cannula. In the newborn kitten (1-6 days old), it was not possible to elicit any effect on injection of PDG into the right atrium. At 1 wk, the visceral reflexes--apnea, rapid shallow breathing, bradycardia--could be produced by doses much higher (six times) than the adult dose. By the 10th day, the visceral reflexes were fully developed. The motor reflex, i.e., inhibition of EMG and reduction of knee jerk, was elicited after 3 wk. The earliest response was seen in a 3-wk-old kitten. All these reflexes were abolished by bilateral cervical vagotomy. These results suggest that the J receptor reflexes are poorly developed in the newborn kitten and that the motor reflexes develop much later than the visceral reflexes. PMID:972120

Kalia, M



Treatment of Lower Extremity Reflex Sympathetic Dystrophy with Continuous Intrathecal Morphine Infusion  

Microsoft Academic Search

Continuous intrathecal morphine infusion has been used in 3 patients with refractory lower extremity reflex sympathetic dystrophy syndromes. Two patients have experienced prolonged significant benefit.

R. R. Goodman; R. Brisman



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

PubMed Central

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

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



The effect of knee joint afferent discharge on transmission in flexion reflex pathways in decerebrate cats.  

PubMed Central

1. Changes in excitability of reflex arcs mediating flexion withdrawal ad crossed extensor reflexes have been examined in decerebrate cats. 2. The excitability of flexion withdrawal and crossed extensor reflexes was shown to be modulated by knee joint position. Flexion withdrawal reflexes were most easily elicited when the knee was extended and crossed extensor reflexes were most easily elicited when the knee was flexed. 3. The modulation of transmission was not confined to reflex pathways to muscles acting at the knee but also included pathways to muscles acting at the hip and ankle, as well as pathways to muscles in the contralateral limb. 4. The changing excitability of reflex pathways caused by movement of the knee joint was unrelated to the stretch applied to muscles acting at the knee and to cutaneous afferent discharge. Modulation of reflex excitability by joint movement was totally abolished by local anaesthesia of the knee joint in an otherwise intact limb. 5. The results of the present experiments indicate that transmission in flexion reflex pathways can be inhibited by knee joint afferent discharge.

Baxendale, R H; Ferrell, W R



Jaw reflexes and masseter electromyograms in mesencephalic and pontine lesions: an electrodiagnostic study.  

PubMed Central

Jaw reflexes and masseter electromyograms were studied in five patients with mesencephalic and 11 patients with pontine lesions, vascular or tumorous in nature. In the former group jaw reflexes were abnormal, being delayed or absent, whereas masseter electromyograms were normal. In the latter group, both jaw reflexes and masseter EMG, showing denervation, were abnormal in six and both normal in five cases. It is suggested that the afferent limb of the human jaw reflex passes through the mesencephalic trigeminal nucleus. The methods proved to be valuable in the diagnosis of mesencephalic and pontine lesions involving the fifth cranial nerve.

Ongerboer De Visser, B W; Goor, C



Electrical study of jaw and orbicularis oculi reflexes after trigeminal nerve surgery.  

PubMed Central

Trigeminal nerve ophthalmic and motor division function was assessed clinically and electrically in 32 patients who had undergone various surgical procedures for trigeminal neuralgia. Using known electrophysiological techniques, the orbicularis oculi and jaw reflexes were tested in all subjects. Abnormalities of the orbicularis oculi reflex were anticipated on the basis of ophthalmic division anaesthesia. However, jaw reflex abnormalities appeared in operated cases with no clinical or electromyographic evidence of masseter denervation. These results were unexpected, and imply that the proprioceptive fibres of the jaw reflex are mediated by a sensory and not a motor root as previously believed. Images

Ferguson, I T



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


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

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



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



Central Cannabinoid Receptors Modulate Acquisition of Eyeblink Conditioning  

ERIC Educational Resources Information Center

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

Steinmetz, Adam B.; Freeman, John H.



Central Cannabinoid Receptors Modulate Acquisition of Eyeblink Conditioning  

ERIC Educational Resources Information Center

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

Steinmetz, Adam B.; Freeman, John H.



Autogenetic reflex action on to gamma motoneurones by stretch of triceps surae in the decerebrated cat.  

PubMed Central

1. Tonically firing gamma motoneurones of known conduction velocity (total eighty-seven, range 15-43 m/sec) have been isolated in peripheral muscular nerves to triceps surae. Their responses to stretch of triceps surae have been studied in decerebrated cats. A small amplitude, quick stretch and release was used to provide a selective stimulus for primary endings of muscle spindles. 2. To check the selectivity, recordings were made from 135 afferents from triceps surae under conditions closely similar to the reflex experiments. The threshold of all but a few primary endings of muscle spindles law below 50 micrometer whereas threshold was above 50 micrometer for the majority of secondary endings and tendon organs. A 20 micrometer stretch excited approximately half the primary endings but only one of thirty-six secondaries and no tendon organs responded to such a small stretch. Nine group III afferents were also studied but none responded to stretch. 3. Stretch of up to 50 micrometer excited twenty-three and inhibited eleven gamma motoneurones while thirty-three remained unaffected. A further twenty showed mixed responses, being inhibited initially before being excited at longer latency. Thresholds for reflex responses of gamma motoneurones frequently occurred below 20 mum and responses were close to maximal for stretch of 50 micrometer. 4. Excitation always had a lower threshold to stretch than did inhibition for those gamma motoneurones showing mixed responses and was the more potent of the two effects. 5. Excitation to stretch had central delays, to the incoming group Ia volley, ranging from 5 to 14 msec while similarly calculated delays for excitation of alpha motoneurones ranged from 0.6 to 3.0 msec. Central delays of the gamma inhibitory responses lay in an intermediate range of 1.7-7.0 msec. 6. The long central delays of excitation of gamma motoneurones in response to stretch do not reflect transmission in supraspinal pathways since the reflex persisted following spinal section. 7. Excitation of gamma motoneurones was weak in comparison with that of tonically firing alpha motoneurones recorded in the same preparations and it was always necessary to sum a number of responses in order to reveal an effect...

Ellaway, P H; Trott, J R



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.



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.



PIV Application to Fluid Dynamicsof Bass Reflex Ports  

Microsoft Academic Search

\\u000a A bass reflex (or vented or ported) loudspeaker system (BRS) is a particular\\u000a type of loudspeaker enclosure that makes use of the combination of two second-order\\u000a mechanic\\/acoustic devices, i.e., the driver and a Helmotz resonator, in order to create\\u000a a new system with reinforced emission in the low frequency region. The resonator is\\u000a composed by the box itself in which one or

Massimiliano Rossi; Enrico Esposito; Enrico Tomasini


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

PubMed Central

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.

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



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


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

Okada, H; Honda, M; Ono, H



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

ERIC Educational Resources Information Center

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

Medova, Lucie



Anesthetic management of the trigeminocardiac reflex during mesiodens removal-a case report.  


We describe a case in which reflection of a palatal flap for removal of a mesiodens is presented as the triggering factor for bradycardia caused by stimulation of the trigeminocardiac reflex. The management of the case, as well as the reflex arc, is discussed. PMID:17352528

Webb, Michael D; Unkel, John H



Anesthetic Management of the Trigeminocardiac Reflex During Mesiodens Removal--A Case Report  

PubMed Central

We describe a case in which reflection of a palatal flap for removal of a mesiodens is presented as the triggering factor for bradycardia caused by stimulation of the trigeminocardiac reflex. The management of the case, as well as the reflex arc, is discussed.

Webb, Michael D; Unkel, John H



The effect of caffeine on the spinal reflexes in warm-blooded animals  

Microsoft Academic Search

Summary The effect of the intravenous injection of caffeine upon flexor and extensor reflexes and reciprocal inhibition was studied on spinal cats. The change of the motor cell excitability was investigated by their direct stimulation with the aid of microelectrodes inserted into the gray matter of the spinal cord. Caffeine provokes biphasic changes in the reflex responses, i.e., the initial

I. A. Zemlyanoi



Role of the parabrachial nuclei in the airway dilation evoked by the Hering-Breuer reflex  

Microsoft Academic Search

We tested the hypothesis that blockade of glutamatergic receptors in the parabrachial nucleus (PBN) of chloralose-anesthetized cats attenuated the reflex airway dilation evoked by activation of pulmonary stretch receptors. Unilateral microinjection of kynurenic acid (50 nl, 100 mM) into the PBN reversibly attenuated the reflex relaxation of the trachealis muscle in 7 cats. These findings suggest that the PBN is

Ann M. Motekaitis; Irene C. Solomon; Marc P. Kaufman



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



What is the desirable stimulus to induce the rectoanal inhibitory reflex?  

Microsoft Academic Search

PURPOSE: This study was designed to find other methods to induce rectoanal inhibitory reflex. METHODS: Twenty healthy children were studied manometrically using three different types of stimuli, air, balloon, and water. RESULTS: Reflex occurred with all three kinds of stimuli; however, the free-air method was more sensitive and convenient than the common inflating balloon method. The lowest feeling amount and

Yang Gang



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