Sample records for conditioned reflexes

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

    E-print Network

    Menzel, Randolf - Institut für Biologie

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

  2. Induced specific immunological unresponsiveness & conditioned behavioral reflexes, in functional isomorphism-meditation and conditioned specific unresponsiveness.

    PubMed

    Freed, S

    1989-02-01

    Detailed functional isomorphism had been observed (Freed, 1984) between induced (conditioned) immunogenicity and classical conditioned defensive reflexes, possibly as evolutionary adaptation against danger at micro and macro levels respectively. Similarly, functional isomorphism is postulated between conditioned specific tolerogenicity of the immunotolerance system and behavioral reflexes. Isomorphism requires that sensory signals elaborated with intrinsic (unconditioned) behavioral tolerogens as carriers do not subsequently combine classically with unconditioned aversive stimuli and evoke conditioned defensive responses. Unconditioned behavioral tolerogenic carriers were identified with behavioral (physiological) activities of Oriental meditation. Confirmation of conditioned behavioral tolerogenicity appeared in the unresponsiveness of Yogi mediators to sensory stimuli as reflected in unchanged alpha rhythms of their encephalograms. Conditioned behavioral specific unresponsiveness maintains the "quiet" of meditation and mediates the experience of Zen mediators, namely, sharpened, clearer perceptions and unresponsiveness to aversive components of current conditioned signals ordinarily reactivating residues of affect. Conditioned behavioral specific unresponsiveness has survival value. PMID:2656566

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

    PubMed

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

    2014-11-15

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

  4. Long-lasting conditioning of the human soleus H reflex following quadriceps tendon tap

    Microsoft Academic Search

    Jianguo Cheng; John D. Brooke; William R. Staines; John E. Misiaszek; Jim Hoare

    1995-01-01

    Percussion of the quadriceps tendon was used to test the hypothesis that knee extensor muscle spindle discharge initiates down-regulation of the gain of the soleus H reflex. Seven subjects participated. Soleus H reflex magnitude was observed for up to 15 s, following conditioning tendon taps of 60 N or 80 N force and 10 ms or 100 ms duration, with

  5. Exercise-induced neuromuscular dysfunction under reflex conditions

    Microsoft Academic Search

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

    2001-01-01

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

  6. Restoring walking after spinal cord injury: operant conditioning of spinal reflexes can help.

    PubMed

    Thompson, Aiko K; Wolpaw, Jonathan R

    2015-04-01

    People with incomplete spinal cord injury (SCI) frequently suffer motor disabilities due to spasticity and poor muscle control, even after conventional therapy. Abnormal spinal reflex activity often contributes to these problems. Operant conditioning of spinal reflexes, which can target plasticity to specific reflex pathways, can enhance recovery. In rats in which a right lateral column lesion had weakened right stance and produced an asymmetrical gait, up-conditioning of the right soleus H-reflex, which increased muscle spindle afferent excitation of soleus, strengthened right stance and eliminated the asymmetry. In people with hyperreflexia due to incomplete SCI, down-conditioning of the soleus H-reflex improved walking speed and symmetry. Furthermore, modulation of electromyographic activity during walking improved bilaterally, indicating that a protocol that targets plasticity to a specific pathway can trigger widespread plasticity that improves recovery far beyond that attributable to the change in the targeted pathway. These improvements were apparent to people in their daily lives. They reported walking faster and farther, and noted less spasticity and better balance. Operant conditioning protocols could be developed to modify other spinal reflexes or corticospinal connections; and could be combined with other therapies to enhance recovery in people with SCI or other neuromuscular disorders. PMID:24636954

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

    E-print Network

    Zehr, Paul

    Effect of Rhythmic Arm Movement on Reflexes in the Legs: Modulation of Soleus H of rhythmic arm movement on reflexes in the legs: modulation of soleus H-reflexes and somatosensory.2003. During locomotor tasks such as walking, running, and swimming, the arms move rhythmically with the legs

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

    E-print Network

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-09-15

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

  11. [Use of conditioned reflex therapy combined with teturam administration in chronic alcoholism].

    PubMed

    Krylovski?, A P; Litvinenko, V I

    1984-01-01

    In order to treat patients who are resistant to antialcohol therapy (110 patients), the authors used sensibilizing therapy throughout the entire course of treatment in conjunction with reflex therapy conducted by using conditional drops (1/20 part of a gulp) of alcohol. This method is technically simple, causes no complications and produces more persistent remissions, e.g. remissions lasting over one year were observed in almost half of the patients (47,2%). PMID:6711217

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

    ERIC Educational Resources Information Center

    Wolpaw, Jonathan R.; Chen, Xiang Yang

    2006-01-01

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

  13. Reflexes in Psychiatry

    PubMed Central

    Sanders, Richard D.

    2011-01-01

    Psychiatric patients often do not cooperate fully with the neurologic examination. Reflexes virtually bypass patient effort and are difficult to consciously determine. This article reviews muscle stretch (deep tendon) reflexes, and pathological reflexes including the extensor plantar (Babinski) and primitive release reflexes. Topics include findings in common psychiatric and neurologic conditions and methods for eliciting these signs. PMID:21637631

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

    PubMed Central

    Thompson, Aiko K.; Wolpaw, Jonathan R.

    2014-01-01

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

  15. [The conditioned avoidance reflex and intersignal movements: the correlation of the cardiac and motor components].

    PubMed

    Dolbakian, E E

    1991-01-01

    In five dogs correlation was studied of heart rate (HR) and motor component of conditioned avoidance reflex (CAR), elaborated by Petropavlovski? method. Stable CAR was expressed in lifting and long (not less than 5-10 sec) holding of the paw on definite height (5-10 cm) for the avoidance of painful electrocutaneous paw stimulation in response to conditioned acoustic stimulus. The level of defensive excitation, evaluated by heart rate change was maximum before the beginning of the conditioned motor reaction. Immediately after lifting and placing the paw in the zone of security a sharp decrease of defensive excitation level ("drive" reduction) took place. Intertrial motor reactions of two types were revealed. The first type imitated the conditioned motor reaction, the second one the usual phasic bending of the paw. Against the background of intertrial movement of the first, operant type a decrease of defensive motivation took similarity as it occurred against the background of CAR during the performance response. PMID:1651617

  16. Moro reflex

    MedlinePLUS

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

  17. EVIDENCE FOR THE INVOLVEMENT OF ASSOCIATIVE CONDITIONING IN REFLEX MODIFICATION OF THE ACOUSTIC STARTLE RESPONSE WITH GAPS IN BACKGROUND NOISE

    EPA Science Inventory

    The experiments reported here were designed to determine the role of associative conditioning in reflex modification of the acoustic startle response using gaps in background noise. xperiments were conducted with independent, naive groups of adult Long Evans hooded rats tested us...

  18. Abnormal conditioning effect of transcranial magnetic stimulation on soleus H-reflex during voluntary movement in Parkinson's disease

    Microsoft Academic Search

    H Morita; M Shindo; S Morita; T Hashimoto; T Tada; S Ikeda

    2002-01-01

    Objectives: The objective of this study is to clarify the participation of cortical motor control abnormality in the motor dysfunction of Parkinson's disease (PD), especially at the onset of movement.Methods: Conditioning effects of transcranial magnetic simulation (TMS) on the soleus (SOL) H-reflex evoked with tibial nerve stimulation were examined in 19 patients with PD and 10 normal volunteers. Experiments were

  19. [Effects of mechanical stimulation of the soles' support zones on H-reflex characteristics under support unloading condition].

    PubMed

    Zakirova, A Z; Shigueva, T A; Tomilovskaya, E S; Kozlovskaya, I B

    2015-01-01

    The aim of the work was to study the effects of mechanical stimulation of the soles' support zones on state of m. soleus motoneurone pool in man under 7-days support unloading conditions, which was provided by "Dry Immersion" model. Before, during and after immersion exposure the excitability of m. soleus motoneurone pool was estimated by H-reflex amplitude normalized by the maximal amplitude of M-wave. The data registered in two groups of volunteers: "control" in which only immersion exposure was used and "experimental" in which stimulation of support zones of sole was carried out during Dry Immersion were compared. During immersion relative amplitude of H-reflex increased in the control group. These alterations were not revealed in the experimental group with daily application of the support stimulation in natural locomotion regimens during immersion. PMID:26027332

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

    PubMed Central

    Burhans, Lauren B.; Schreurs, Bernard G.

    2013-01-01

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

  1. Caring Reflexivity

    ERIC Educational Resources Information Center

    Rallis, Sharon F.; Rossman, Gretchen B.

    2010-01-01

    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…

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

    PubMed

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

    2014-03-01

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

  3. Experimenting With Baroreceptor Reflexes

    NASA Technical Reports Server (NTRS)

    Eckberg, Dwain L.; Goble, Ross L.

    1988-01-01

    Carotid arteries stimulated by pressure or suction on neck. Baro-Cuff is silicone-rubber chamber that fits on front of subject's neck. Electronic system, stepping motor, bellows, and umbilical tube furnish controlled pressure to chamber. Pressure sensor provides feedback to microprocessor in electronic system. Developed to study blood-pressure-reflex responses of astronauts in outer space. Useful for terrestrial studies of patients with congestive heart failure, chronic diabetes mellitus, and other conditions in which blood-pressure-reflex controls behave abnormally.

  4. Reflexes and the eye.

    PubMed

    Hunyor, A P

    1994-08-01

    Reflexes are an essential part of protective and homeostatic function, both in general terms and with specific reference to ocular structures. A wide range of stimuli and responses, with varying degrees of central processing, is involved in such reflexes. The simplest reflexes are monosynaptic, such as the stretch or myotatic reflex. More complex polysynaptic reflexes are involved in many regulatory and protective functions--these include autonomic as well as somatic reflexes. Ocular autonomic reflexes include the oculocardiac, pupillary, accommodative and lacrimatory reflexes. Ocular somatic reflexes include eyelid and extra-ocular muscle reflexes (such as Bell's phenomenon, vestibulo-ocular and optokinetic reflexes). An account of the above reflexes is given in the format of an essay, modified from the FRACO Part I Examination in Physiology. The topic was 'Discuss reflex activities with particular reference to the eye'. The content is based on several of the texts recommended for the Part I Examination, as listed under references. PMID:7818872

  5. Functional relationships between myotatic reflex arcs of the lower limb in man: investigation by excitability curves

    Microsoft Academic Search

    P J Delwaide; M Cordonnier; M Charlier

    1976-01-01

    In 30 normal subjects, the influence of the reflex activation of one myotatic reflex arc on the excitability of other myotatic reflex arcs of the lower limb has been investigated using excitability curves. Soleus, quadriceps, and short biceps tendon reflexes as well as H reflex at two different intensities (liminal and H max\\/2) were used either as conditioning or as

  6. Wireless quantified reflex device

    NASA Astrophysics Data System (ADS)

    Lemoyne, Robert Charles

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

  7. Vestibular-Ocular Reflex

    NSDL National Science Digital Library

    Marlene Y. MacLeish, Ed.D.

    2013-01-30

    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.

  8. Differential Effects of Noxious Conditioning Stimulation of the Cheek by Capsaicin on Human Sensory and Inhibitory Masseter Reflex Responses Evoked by Tooth Pulp Stimulation

    Microsoft Academic Search

    P. Kemppainen; A. Waltimo; T. Waltimo; M. Könönen; A. Pertovaara

    1997-01-01

    In this study, we investigated whether selective activation of nociceptive primary afferent fibers by capsaicin would induce modulations on tooth-pulp-evoked sensory or inhibitory masseter reflex responses in healthy human subjects. The contribution of central N-methyl-D-aspartate (NMDA) receptor mechanisms in capsaicin-induced effects on sensory or reflex responses was evaluated by dextromethorphan, an NMDA-receptor antagonist. The inhibitory masseter reflex was evoked by

  9. Differential Effects ofNoxious Conditioning Stimulation oftheCheekbyCapsaicin onHumanSensory andInhibitory Masseter Reflex Responses Evoked byTooth PulpStimulation

    Microsoft Academic Search

    P. Kemppainenl; A. Waltimol; T. Waltimol; M. Kononen

    Inthis study, weinvestigated whether selective activation ofnociceptive primary afferent fibers bycapsaicin wouldinduce modulations ontooth-pulp-evoked sensory or inhibitory masseter reflex responses inhealthy humansubjects. Thecontribution ofcentral N-methyl-D-aspartate (NMDA) receptor mechanisms incapsaicin-induced effects onsensory or reflex responses wasevaluated bydextromethorphan, an NMDA-receptor antagonist. Theinhibitory masseter reflex was evoked byelectrical stimulation (constant current, single puLses) oftheupper incisor while thesubject wasbiting at10% ofhismaximalforce. Thesensation ofthetooth pulp

  10. Farhan Imtiaz Emergence of Reflexive

    E-print Network

    Daraio, Chiara

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

  11. [Natural 1st and 2d degree conditioned food reflexes in the dog in relation to space orientation].

    PubMed

    Simonov, P V; Rudenko, L P

    1985-01-01

    In three dogs formation and performance of spatial alimentary natural conditioned responses of the second order was studied when the dog had to find food preliminarily shown to it in one of the four food-distributors (psychonervous activity directed by a food image in terms proposed by I. S. Beritashvili). Characteristics of this form of behaviour were demonstrated and discussed: rapid formation, dependence of performance on the delay time, conflict between responses of the first and the second order. In the second series of the experiments food-procuring behaviour of dogs was studied under conditions of conflict between the quality (value) of alimentary reinforcement and probability of its finding in certain food-distributor. Such kind of behavior was shown to depend on the motivation level and individual characteristics of the dog. Interaction of "informational" (anterior areas of the neocortex, hippocampus) and "motivational" (nuclei of amigdalar complex, hypothalamus) cerebral structures is supposed to underlie the organization of behaviour. PMID:3984509

  12. Human jaw reflexes.

    PubMed

    Lund, J P; Lamarre, Y; Lavigne, G; Duquet, G

    1983-01-01

    Although the jaw reflexes are analogous in many ways to the corresponding limb reflexes, important differences do exist. The myotatic reflex appears to contribute more stiffness to the jaw-closing muscles than to limb muscles. The jaw tends to swing up and down during locomotion, and, to maintain a stable position in relationship to the skull, it is necessary that the muscles be made stiff by tonic contraction and/or through a powerful servoreflex. The short conduction pathway and rapid contraction of jaw muscles allow reflex effects to act with little phase lag and to provide efficient compensation. If limb muscle reflexes were equally powerful, their effects could be of more nuisance than help in overcoming expected loads because they occur so late. Perhaps the lack of Renshaw cell inhibition of trigeminal MNs and the potentiation of the jaw jerk reflex by chin vibration are features designed to maintain the strength of the myotatic reflex during locomotion. The jaw-opening reflex (including exteroceptive suppression of jaw-closer muscle activity) is bilaterally symmetrical rather than bilaterally reciprocal, as are the analogous spinal flexor withdrawal reflexes. Bilateral braking is necessary to stop closure, because the mandible crosses the midline, whereas withdrawal of a limb often needs to be compensated for by extension of the other to maintain balance. It has recently been shown in animals that limb and jaw reflex responses are highly context dependent: the size and direction of limb reflexes depend on the phase of locomotion (Forssberg et al., 1977), and the gain of the jaw-opening reflex is increased during the closing phase of mastication (Lund et al., 1981). PMID:6660120

  13. The spinal reflex cannot be perceptually separated from voluntary movements.

    PubMed

    Ghosh, Arko; Haggard, Patrick

    2014-01-01

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

  14. Self-organization of reflexive behavior from spontaneous motor activity.

    PubMed

    Marques, Hugo Gravato; Imtiaz, Farhan; Iida, Fumiya; Pfeifer, Rolf

    2013-02-01

    In mammals, the development of reflexes is often regarded as an innate process. However, recent findings show that fetuses are endowed with favorable conditions for ontogenetic development. In this article, we hypothesize that the circuitry of at least some mammalian reflexes can be self-organized from the sensory and motor interactions brought forth in a musculoskeletal system. We focus mainly on three reflexes: the myotatic reflex, the reciprocal inhibition reflex, and the reverse myotatic reflex. To test our hypothesis, we conducted a set of experiments on a simulated musculoskeletal system using pairs of agonist and antagonist muscles. The reflex connectivity is obtained by producing spontaneous motor activity in each muscle and by correlating the resulting sensor and motor signals. Our results show that, under biologically plausible conditions, the reflex circuitry thus obtained is consistent with that identified in relation to the analogous mammalian reflexes. In addition, they show that the reflex connectivity obtained depends on the morphology of the musculoskeletal system as well as on the environment that it is embedded in. PMID:23053431

  15. On Reflexive Data Models

    SciTech Connect

    Petrov, S.

    2000-08-20

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

  16. Amplitude modulation of the human quadriceps tendon jerk reflex during gait

    Microsoft Academic Search

    V. Dietz; M. Bischer; M. Faist; M. Trippel

    1990-01-01

    Amplitude modulation of the quadriceps tendon jerk reflex was investigated during the step cycle in normal human subjects. Reflex amplitude was compared with that obtained during a control stance condition, with “equivalent” levels of EMG activity and limb position. During gait there was a progressive decrease in the reflex amplitude early in the stance phase, i.e. during yielding of the

  17. Monitoring of head injury by myotatic reflex evaluation

    PubMed Central

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

    2000-01-01

    OBJECTIVES—(1) To establish the feasibility of myotatic reflex measurement in patients with head injury. (2) To test the hypothesis that cerebral dysfunction after head injury causes myotatic reflex abnormalities through disordered descending control. These objectives arise from a proposal to use reflex measurements in monitoring patients with head injury.?METHODS—The phasic stretch reflex of biceps brachii was elicited by a servo-positioned tendon hammer. Antagonist inhibition was evoked by vibration to the triceps. Using surface EMG, the amplitude of the unconditioned biceps reflex and percentage antagonist inhibition were measured. After standardisation in 16 normal adult subjects, the technique was applied to 36 patients with head injury across the range of severity. Objective (1) was addressed by attempting a measurement on each patient without therapeutic paralysis; three patients were also measured under partial paralysis. Objective (2) was addressed by preceding each of the 36 unparalysed measurements with an assessment of cerebral function using the Glasgow coma scale (GCS); rank correlation was employed to test a null hypothesis that GCS and reflex indices are unrelated.?RESULTS—In normal subjects, unconditioned reflex amplitude exhibited a positive skew requiring logarithmic transformation. Antagonist inhibition had a prolonged time course suggesting presynaptic mechanisms; subsequent measurements were standardised at 80 ms conditioning test interval (index termed "TI80").? Measurements were obtained on all patients, even under therapeutic paralysis (objective (1)). The unconditioned reflex was absent in most patients with GCS less than 5; otherwise it varied little across the patient group. TI80 fell progressively with lower GCS, although patients' individual GCS could not be inferred from single measurements. Both reflex indices correlated with GCS (p<0.01), thereby dismissing the null hypothesis (objective (2)).?CONCLUSION—Cerebral dysfunction in head injury is reflected in myotatic reflex abnormalities which can be measured at the bedside. With greater reproducibility, reflex measurements may assist monitoring of patients with head injury.?? PMID:10766887

  18. The inflammatory reflex

    Microsoft Academic Search

    Kevin J. Tracey

    2002-01-01

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

  19. Cockcrow reflex epilepsy

    Microsoft Academic Search

    Agostino Nappo

    1995-01-01

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

  20. Reflexivity in Pigeons

    ERIC Educational Resources Information Center

    Sweeney, Mary M.; Urcuioli, Peter J.

    2010-01-01

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

  1. Superposition of H reflexes on steady contractions in man.

    PubMed Central

    Rüegg, D G; Krauer, R; Drews, H

    1990-01-01

    1. The aim of the investigation was to study the influence of steady isometric contractions on H reflexes of human soleus muscle. 2. Stimulating and recording conditions were hardly affected by plantar flexions which subjects maintained in a force matching task. 3. If the interval between a preceding control and the test stimulus was less than 8 s the test H reflex was depressed in the relaxed subject. The depression was diminished or removed if the test reflex was superimposed on a background activity. The interval between control and test H reflex was at least 8 s in the following experiments. 4. H reflexes were nearly independent of steady plantar flexions on which they were superimposed. In some subjects, there was a slight increase with increasing torque. During dorsal flexions, H reflexes in all subjects were inhibited with increasing torque. 5. The relationship between test H reflexes, control H reflexes and background activity was evaluated by varying pseudo-randomly stimulus intensity and steady flexion torque. The surface defined by this three-dimensional relation approximated a plane suggesting linear properties of the H reflex. In some subjects threshold intensity decreased slightly with torque, in others it was constant. 6. In response to a warning signal, human subjects initiated steady plantar or dorsal flexions in both feet and, at the same time, they started to concentrate on a light at the onset of which they performed a unilateral ballistic plantar contraction as fast as possible. The relations between H reflex and maintained flexion force during the warning period of the reaction time task were identical to those during force matching, showing that the behavioural context did not modulate the relations. 7. The relations were also the same if reflexes were evoked bi- or unilaterally, illustrating the absence of a mutual modification of simultaneously evoked H reflexes. 8. The relation was the same with ipsilateral matching and relaxed contralateral muscles as with bilateral matching. If the ipsilateral side stayed flaccid contralateral matching increased H reflexes by about 20% above control values. 9. It was concluded that various factors can combine to produce an increase of H reflexes with torque, the most important of them being the use of short intervals between H reflexes. We have various evidence from the present experiments for believing that, in the relaxed subjects, the subliminal fringe was small and that although stimulus intensities below threshold could evoke an afferent volley, the effect of this on low-threshold motor units was prevented by presynaptic inhibition at the Ia terminals. PMID:2213593

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  3. Corporeal reflexivity and autism.

    PubMed

    Ochs, Elinor

    2015-06-01

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

  4. Evaluation of a wireless three dimensional MEMS accelerometer reflex quantification device using an artificial reflex system

    Microsoft Academic Search

    Robert LeMoyne; Cristian Coroian; Timothy Mastroianni

    2009-01-01

    An essential aspect for the neurological examination is the assessment of the deep tendon reflex. The deep tendon reflex is commonly conducted by a clinician through evoking the patellar tendon reflex. The significant parameters are the reflex response and the latency of the reflex loop. The characteristics of the reflex response and latency are representative of the severity and status

  5. Baroreceptor Reflex Role Play

    NSDL National Science Digital Library

    2012-06-26

    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.

  6. Calcitonin and reflex sympathetic dystrophy syndrome

    Microsoft Academic Search

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

    1986-01-01

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

  7. Reflex Epilepsy Triggered by Smell.

    PubMed

    Ilik, Faik; Pazarli, Ahmet Cemal

    2015-07-01

    Reflex epilepsies can be provoked by various types of external stimuli, but triggered by smell is rare in the literature. In this case report, we present a patient whose reflex epilepsy is triggered by smell. Physical examination findings and electrophysiologic studies of the patient are discussed. PMID:25013184

  8. Patterning of somatosympathetic reflexes

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  9. Electron dynamics in the bremsstrahlung reflex triode

    Microsoft Academic Search

    R. A. Stark

    2002-01-01

    Summary form only given. The reflex triode is a versatile bremsstrahlung source for Nuclear Weapons Effects simulation. The reflex triode employs a rangethin 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. The reflex triode can operate in the high total dose mode;

  10. Fractionated myotatic reflex times in women by activity level and age.

    PubMed

    Hart, B A

    1986-05-01

    A lifetime habit of participation in vigorous physical exercise has been associated with the maintenance of efficient neuromuscular performance into old age. During test sessions on three consecutive days, measures of fractioned patellar (knee-jerk) reflex times under normal and Jendrassik conditions were obtained from 60 female participants classified as old inactive, old active, young inactive, or young active. A three-factor analysis of variance showed that age/activity group differences were present for reflex latency, but not for reflex motor time or total reflex time. Age differences were demonstrated for degree of reflex facilitation resulting from the Jendrassik maneuver. The results demonstrate that the functional reflex is well maintained into the sixth decade, but that sensitivity to Jendrassik facilitation of the pathway is diminished with age. PMID:3700986

  11. Electromechanical analogs of human reflexes.

    PubMed

    Littman, M G; Liker, M; Stubbeman, W; Russakow, J; McGee, C; Gelfand, J; Call, B J

    1989-01-01

    The conclusion to be drawn from our modeling is that the combined stretch and tendon reflexes alone can endow artificial muscle with a springlike feel as well as give it a baseline tone. In response to questions that motor physiologists often ask as to what variables the system controls, the answer here is clear: the stretch and tendon reflexes act together to maintain both a tension set-point and a length set-point, but in so doing they also give the system a springlike feel because of the existence of a servo error. The main goal of our studies is to understand the integration of reflexes, and thus far we have only begun to explore the two lowest-level spinal reflexes. We are in the process of expanding this work by developing a much more refined arm explicitly modeled after the human arm. This new arm is to be activated by a minimum of 10 muscles, each of which is reflexively driven, and it will allow us to explore the integration of higher-level reflex action such as automatic inhibition of antagonists and facilitation of synergists. PMID:2774411

  12. Vestibulo-spinal reflex mechanisms

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.

    1981-01-01

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

  13. Medio-lateral balance adjustments preceding reflexive limb withdrawal are modified by postural demands

    Microsoft Academic Search

    Leah R Bent; Jim R Potvin; John D Brooke; William E McIlroy

    2001-01-01

    We have recently observed medio-lateral balance adjustments (BA) preceding reflexive stepping elicited by noxious stimulation. While task specific modulation is evident for BA prior to voluntary leg movement, it is unclear whether rapid BA reactions (prior to ‘reflexive’ stepping) represent a generic response to evoked limb withdrawal or can be modified to suit task-conditions. This study was designed to establish

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

    Microsoft Academic Search

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

    1993-01-01

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

  15. Effect of high ambient temperature on the kinetics of the pupillary light reflex in healthy volunteers.

    PubMed Central

    Leung, N K; Bradshaw, C M; Szabadi, E

    1992-01-01

    Miotic responses to brief light stimuli were studied in healthy volunteers under two ambient temperature conditions, 22 degrees C and 40 degrees C. The latency and amplitude of the light reflex did not differ between the two conditions, but the recovery time of the reflex was significantly shorter under the 40 degrees C condition than under the 22 degrees C condition. The results are consistent with the hypothesis that exposure to high ambient temperature results in an increased sympathetic drive to the iris dilator muscle but does not influence the parasympathetic light reflex. PMID:1576072

  16. Reflex seizures in Rett syndrome.

    PubMed

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

    2011-12-01

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

  17. Response to sudden torques about ankle in man: myotatic reflex.

    PubMed

    Gottlieb, G L; Agarwal, G C

    1979-01-01

    1. Sudden dorsiflexions and plantarflexions of the foot were imposed on normal human subjects under various states of voluntary activity. 2. Under conditions of constant muscle contraction, the myotatic reflex in soleus and lateral gastrocnemius muscles is linearly and highly correlated with the rate of muscle stretch. The slope of this curve characterizes part of the reflex arc "gain." 3. The gain is linearly proportional to the level of tonic voluntary activation. 4. The gain is reduced by tonic contraction of antagonists. 5. The above statements can be summarized by the following equation (formula: see text), where d theta/dt is the rate of joint rotation. Ts and Tat are measures of voluntary contraction (tension) of all the extensor and flexor muscles acting at the ankle. The term S represents the level of preexisting spinal excitability that can be altered by prior instruction to the subject. 6. A phasic voluntary contraction of the soleus muscle, which leads to muscle shortening, will alter the reflex gain. The gain initially increases with increasing rates of shortening, but at higher rates the gain is reduced. This is in contradiction to the observation for tonic activation as stated above and may be due to an inability of the coactivated fusimotor system to produce sufficiently rapid cocontraction of the spindle fibers. 7. During lengthening of a muscle caused by voluntary contraction of its antagonists, the myotatic reflex gain is reduced. 8. The above facts are interpreted to imply that a functional role for the myotatic reflex in the leg extensors is limited to conditions of postural maintenance or slow, precise movement. During rapid movement, the myotatic reflex is ineffective and load-compensating reactions are mediated by longer latency loops. 9. The duration of the myotatic reflex EMG is from 10 to 40 ms, too brief to be a simple response to a velocity-sensing receptor organ. Either the response is in large measure due to the initial burst of spindle activity that occurs at the start of a ramp stretch, or motoneuron pool dynamics act as a high-pass filter on afferent inputs. 10. In the anterior tibial muscle, the relationships between stretch velocity and reflex amplitude and tonic voluntary contraction and reflex gain are qualitatively similar to those found in the ankle extensors. PMID:430116

  18. Axially evoked postural reflexes: influence of task.

    PubMed

    Govender, Sendhil; Dennis, Danielle L; Colebatch, James G

    2015-01-01

    Postural reflexes were recorded in healthy subjects (n = 17) using brief axial accelerations and tap stimuli applied at the vertebra prominens (C7) and manubrium sterni. Short latency (SL) responses were recorded from the soleus, hamstrings and tibialis anterior muscles and expressed as a percentage of the background EMG prior to stimulus onset. In the majority of postural conditions tested, subjects were recorded standing erect and leaning forward with their feet together. The SL response was larger for soleus than for the hamstrings during standing (soleus vs hamstrings; 70.4 vs 28.1%), whereas the opposite occurred during kneeling (25.3 vs 127.3%). Concordant head and trunk accelerations produced larger SL responses than discordant accelerations for soleus and hamstrings, but the evoked excitatory response was independent of head direction and as expected for the direction of truncal acceleration. Postural reflexes for soleus and tibialis anterior were strongly affected by conditions that posed a significant threat to postural stability; stimulation at C7 was associated with significant SL enhancement for soleus during anterior lean while sternal stimulation showed SL enhancement for tibialis anterior during posterior lean. Cutaneous anaesthesia applied over the C7 stimulation site had no significant effect on EMG responses, nor did vision or surface type (rigid or compliant). This study provides further evidence that postural reflexes produced by brief axial accelerations are independent of cutaneous receptors, vestibular afferents and ankle proprioceptors, and demonstrates that postural tasks and truncal orientation significantly affect the evoked response, consistent with a role in stabilising posture. PMID:25300958

  19. Effect of cervicolabyrinthine impulsation on the spinal reflex apparatus

    NASA Technical Reports Server (NTRS)

    Yarotskiy, A. I.

    1980-01-01

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

  20. Sensitization of enteric reflexes in the rat colon in vitro.

    PubMed

    Furness, John B; Kumano, Kimitsuka; Larsson, Håkan; Murr, Elise; Kunze, Wolfgang A A; Vogalis, Fivos

    2002-04-18

    We have investigated sensitization of reflexes in the isolated rat colon in order to develop a model that might prove useful for investigating how the sensitivity of enteric reflexes can be altered by prior stimulation. Records were taken of circular muscle tension, 7-10 mm oral and anal to radial distension exerted by a hook passed through the wall of the colon. A test stimulus of 1.5 g produced consistent contractions both oral and anal to the distension. A conditioning protocol, consisting of repeated application of 3 g for 30 s with 30 s between the stimuli for 30 min, doubled the amplitudes of reflex contractions that were evoked by the test stimuli but did not change the sensitivity of the muscle to the direct action of carbachol. The enhanced responses persisted for at least 40 min. The enhancement of reflexes was not reduced by antagonists of tachykinin NK3 receptors or of 5-HT3 receptors, but the reflex oral to stimulation was reduced by NK1 and NK3 antagonists added together. Sensitization was abolished by the cyclo-oxygenase and thromboxane synthase inhibitor, indomethacin. We conclude that sensitization can be reliably induced in vitro and that the model described in the present work can be used to investigate drugs that interfere with the sensitization process. PMID:12036182

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

    PubMed

    Gibson, W; Campbell, A; Allison, G

    2013-09-01

    Motor output in activities such as walking and hopping is suggested to be mediated neurally by purported stretch reflex augmentation of muscle output. Reflex EMG activity during these tasks has been frequently investigated in the soleus muscle; with alterations in reflex amplitude being associated with changes in hip joint angle/phase of the gait cycle. Previous work has focussed on reflex activity induced by an artificial perturbation or by induction of H-reflexes. As such, it is currently unknown if stretch reflex activity induced intrinsically (as part of the task) is modulated by changes in hip joint angle. This study investigated whether hip joint angle modulated reflex EMG 'burst' activity during a hopping task performed on a custom-built partially reclined sleigh. Ten subjects participated; EMG and kinematic data (VICON motor capture system) was collected for each hop cycle. Participants completed 5 sets of 30s of self-paced hopping in (1) hip neutral and (2) hip 60° flexion conditions. There was no difference in EMG 'burst' activity or in sagittal plane kinematics (knee/ankle) in the hopping task between the two conditions. The results indicate that during a functional task such as hopping, changes in hip angle do not alter the stretch reflex-like activity associated with landing. PMID:23791780

  2. Electron dynamics in the bremsstrahlung reflex triode

    Microsoft Academic Search

    R. A. Stark

    2002-01-01

    The reflex triode is a versatile bremsstrahlung source for Nuclear Weapons Effects simulation. The reflex triode employs a range-thin foil anode between two identical face-to-face hollow cathodes. Electrons undergo multiple reflexes through the anode foil converter as they lose their energy and are focused radially. The reflex triode can operate in the high total dose mode; the high dose rate

  3. Axillary Brachial Plexus Blockade for the Reflex Sympathetic Dystrophy Syndrome.

    ERIC Educational Resources Information Center

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

    1997-01-01

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

  4. Afferent Limb of the Myotatic Reflex Arc

    Microsoft Academic Search

    A. K. McIntyre

    1951-01-01

    WITHIN the past decade, the use of electronic methods has laid bare much of the mechanism underlying the myotatic, or stretch, reflex of mammalian striated muscle. Outstanding among these advances are Lloyd's demonstration of the monosynaptic nature of the myotatic reflex pathway, and his disclosure that fibres of large diameter (Group I fibres) constitute the afferent limb of this reflex

  5. Some observations on spinal reflexes in man

    Microsoft Academic Search

    J. W. Magladery

    1955-01-01

    An attempt has been made to assess the functional significance of certain spinal reflexes demonstrable in man, and to consider their relationships to tendon jerks and tonus. Selected older studies have been reviewed in light of current knowledge of stretch reflex activity. The physiological basis of the electrically induced reflexes first described by Paul Hoffmann has been more strictly defined.

  6. Reflexive aerostructures: increased vehicle survivability

    NASA Astrophysics Data System (ADS)

    Margraf, Thomas W.; Hemmelgarn, Christopher D.; Barnell, Thomas J.; Franklin, Mark A.

    2007-04-01

    Aerospace systems stand to benefit significantly from the advancement of reflexive aerostructure technologies for increased vehicle survivability. Cornerstone Research Group Inc. (CRG) is developing lightweight, healable composite systems for use as primary load-bearing aircraft components. The reflexive system is comprised of piezoelectric structural health monitoring systems, localized thermal activation systems, and lightweight, healable composite structures. The reflexive system is designed to mimic the involuntary human response to damage. Upon impact, the structural health monitoring system will identify the location and magnitude of the damage, sending a signal to a discrete thermal activation control system to resistively heat the shape memory polymer (SMP) matrix composite above activation temperature, resulting in localized shape recovery and healing of the damaged areas. CRG has demonstrated SMP composites that can recover 90 percent of flexural yield stress and modulus after postfailure healing. During the development, CRG has overcome issues of discrete activation, structural health monitoring integration, and healable resin systems. This paper will address the challenges associated with development of a reflexive aerostructure, including integration of structural health monitoring, discrete healing, and healable shape memory resin systems.

  7. Intracranial causes of ophthalmoplegia: the visual reflex pathways.

    PubMed

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

    2013-01-01

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

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

    PubMed

    Chapple, W D

    1985-08-01

    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

  9. The organization of heterogenic reflexes among muscles crossing the ankle joint in the decerebrate cat.

    PubMed Central

    Nichols, T R

    1989-01-01

    1. Mechanical actions of heterogenic (intermuscular) reflexes arising from proprioceptors in flexor and extensor ankle muscles were measured in intercollicular and premammillary decerebrate cats. Length inputs were applied to the freed tendons of one of a pair of muscles crossing the ankle joint and resulting changes in force in both muscles were measured. Interactions between autogenic and heterogenic reflexes were studied by applying length changes to both muscles. 2. A consistent asymmetry was observed in the heterogenic inhibition between the single-joint antagonists soleus and tibialis anterior (TA). Inhibition from soleus to TA was weak or absent during the reflex activation of TA. In contrast, a strong heterogenic inhibition was consistently observed from TA to soleus during the activation of soleus by a crossed-extension reflex. The effect of this inhibition in the intact joint is to increase the apparent mechanical stiffness of soleus. 3. Mutual synergism among soleus, medial gastrocnemius (MG) and lateral gastrocnemius (LG) was demonstrated only at low to moderate forces by the observation of excitatory reflexes among them. During a naturally or electrically evoked crossed-extension reflex, however, a unidirectional inhibitory reflex from MG and LG to soleus was observed. This inhibition increased with force in MG or LG. These results suggest that the knee and ankle joints become more tightly linked mechanically at high forces since the stiffness of the biarticular gastrocnemius muscle predominates over that of the uniarticular soleus. 4. Under quiescent conditions (no resting muscle activation), mutual synergism was obeyed among the ankle extensors soleus, LG and MG and also between the pretibial flexors TA and extensor digitorum longus (EDL). Moreover, inhibition was generally observed between a pretibial flexor and an ankle extensor. Departures from this expected pattern of heterogenic reflexes occurred when the muscle groups were activated by crossed-extension and flexion reflexes. Reflexes onto soleus, TA and EDL reversed in sign or increased in magnitude. 5. The observed patterns of reflex connectivity among the ankle flexors and extensors were similar in both intercollicular and premammillary preparations, although changes in reflex strength were sometimes noted in cases where a second, lower transection was performed during the experiment. 6. It is argued from the large magnitudes of certain heterogenic reflexes that the mechanical response properties of muscles crossing the ankle joint in the intact animal are not dominated by autogenic reflexes and intrinsic mechanical properties.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2795487

  10. Human stretch reflex pathways reexamined

    PubMed Central

    Yavuz, ?. Utku; Mrachacz-Kersting, Natalie; Sebik, O?uz; Berna Ünver, M.; Farina, Dario

    2013-01-01

    Reflex responses of tibialis anterior motor units to stretch stimuli were investigated in human subjects. Three types of stretch stimuli were applied (tap-like, ramp-and-hold, and half-sine stretch). Stimulus-induced responses in single motor units were analyzed using the classical technique, which involved building average surface electromyogram (SEMG) and peristimulus time histograms (PSTH) from the discharge times of motor units and peristimulus frequencygrams (PSF) from the instantaneous discharge rates of single motor units. With the use of SEMG and PSTH, the tap-like stretch stimulus induced five separate reflex responses, on average. With the same single motor unit data, the PSF technique indicated that the tap stimulus induced only three reflex responses. Similar to the finding using the tap-like stretch stimuli, ramp-and-hold stimuli induced several peaks and troughs in the SEMG and PSTH. The PSF analyses displayed genuine increases in discharge rates underlying the peaks but not underlying the troughs. Half-sine stretch stimuli induced a long-lasting excitation followed by a long-lasting silent period in SEMG and PSTH. The increase in the discharge rate, however, lasted for the entire duration of the stimulus and continued during the silent period. The results are discussed in the light of the fact that the discharge rate of a motoneuron has a strong positive linear association with the effective synaptic current it receives and hence represents changes in the membrane potential more directly and accurately than the other indirect measures. This study suggests that the neuronal pathway of the human stretch reflex does not include inhibitory pathways. PMID:24225537

  11. Gastric sensitivity and reflexes: basic mechanisms underlying clinical problems.

    PubMed

    Azpiroz, Fernando; Feinle-Bisset, Christine; Grundy, David; Tack, Jan

    2014-02-01

    Both reflex and sensory mechanisms control the function of the stomach, and disturbances in these mechanisms may explain the pathophysiology of disorders of gastric function. The objective of this report is to perform a literature-based critical analysis of new, relevant or conflicting information on gastric sensitivity and reflexes, with particular emphasis on the comprehensive integration of basic and clinical research data. The stomach exerts both phasic and tonic muscular (contractile and relaxatory) activity. Gastric tone determines the capacity of the stomach and mediates both gastric accommodation to a meal as well as gastric emptying, by partial relaxation or progressive recontraction, respectively. Perception and reflex afferent pathways from the stomach are activated independently by specific stimuli, suggesting that the terminal nerve endings operate as specialized receptors. Particularly, perception appears to be related to stimulation of tension receptors, while the existence of volume receptors in the stomach is uncertain. Reliable techniques have been developed to measure gastric perception and reflexes both in experimental and clinical conditions, and have facilitated the identification of abnormal responses in patients with gastric disorders. Gastroparesis is characterised by impaired gastric tone and contractility, whereas patients with functional dyspepsia have impaired accommodation, associated with antral distention and increased gastric sensitivity. An integrated view of fragmented knowledge allows the design of pathophysiological models in an attempt to explain disorders of gastric function, and may facilitate the development of mechanistically orientated treatments. PMID:24306100

  12. Cultural reflexivity in health research and practice.

    PubMed

    Aronowitz, Robert; Deener, Andrew; Keene, Danya; Schnittker, Jason; Tach, Laura

    2015-07-01

    Recent public health movements have invoked cultural change to improve health and reduce health disparities. We argue that these cultural discourses have sometimes justified and maintained health inequalities when those with power and authority designated their own social practices as legitimate and healthy while labeling the practices of marginalized groups as illegitimate or unhealthy. This "misrecognition," which creates seemingly objective knowledge without understanding historical and social conditions, sustains unequal power dynamics and obscures the fact that what is deemed legitimate and healthy can be temporally, geographically, and socially relative. We use examples from research across multiple disciplines to illustrate the potential consequences of cultural misrecognition, highlight instances in which culture was invoked in ways that overcame misrecognition, and discuss how cultural reflexivity can be used to improve health research and practice. PMID:25905833

  13. Reflex assessment of a reciprocal inhibition between bifunctional ago-antagonist muscles.

    PubMed

    Pérot, C; Mora, I; Goubel, F

    1994-01-01

    Neuronal connections between the peroneus longus and the soleus, ago-antagonist bifunctional muscles, were investigated by reflex analysis. The peroneus longus H-reflex, obtained by stimulating the common peroneal nerve, was conditioned by a posterior tibial nerve stimulation. This conditioning stimulus induced an early inhibition of the peroneus longus H-reflex and the degree of inhibition increased with the conditioning stimulus intensity. The soleus H-reflex, solicited by stimulating the posterior tibial nerve, was conditioned by passive adduction movements. These movements were passive quick-release movements achieved by a specific device containing an electromagnet and stiff springs. The passive adduction movement induced both a myotatic reflex in the stretched muscles and an early inhibition of the test soleus H-reflex. This inhibition is most likely due to the activation of the primary spindle afferents of the stretched muscles. Thus we propose an antagonist neuronal scheme between peroneus longus and soleus muscles in spite of their agonism in plantarflexion. PMID:20870550

  14. Modulation of slow and fast elbow extensor EMG tonic activity by stretch reflexes in man

    Microsoft Academic Search

    K. Bejaoui; S. Le Bozec; B. Maton

    1987-01-01

    Summary  Reflex EMG responses to sudden passive flexion of the elbow were recorded from anconeus and triceps brachii in 5 human volunteers.While the subjects were required not to resist the flexion movement, they were required to maintain an extension torque of 3.5 or 7.0 Nm prior to its onset.Under these isotonic conditions, the latency and amplitude of the reflex activities from

  15. Effect of aluminum consumption on the vestibulo-ocular reflex

    Microsoft Academic Search

    O. Mameli; M. A. Caria; P. Melis; P. Zambenedetti; M. Ramila; P. Zatta

    2006-01-01

    The effects of chronic exposure (90 days) to Aluminum chloride (AlCl3) were analyzed in 3, 10 and 24 month old male rats (n=270) by investigating the function of the VOR (vestibulo-ocular reflex) in correlation with Aluminum (Al) concentrations\\u000a in blood and brain. The VOR was chosen and tested in basal conditions (pre-exposure measures) and during the continuous administration\\u000a of three

  16. Reflexivity: Towards a Theory of Lifelong Learning.

    ERIC Educational Resources Information Center

    Edwards, Richard; Ranson, Stewart; Strain, Michael

    2002-01-01

    The current notion of lifelong learning in policy and practice is dominated by behaviorist, adaptive accumulation of skills and qualifications. An alternative is reflexive lifelong learning, developed through social learning networks within the context of dislocation and uncertainty. It involves the reflexive practices of metacognitive analysis…

  17. Reflexive composites: self-healing composite structures

    Microsoft Academic Search

    Thomas W. Margraf Jr.; Thomas J. Barnell; Ernie Havens; Christopher D. Hemmelgarn

    2008-01-01

    Cornerstone Research Group Inc. has developed reflexive composites achieving increased vehicle survivability through integrated structural awareness and responsiveness to damage. Reflexive composites can sense damage through integrated piezoelectric sensing networks and respond to damage by heating discrete locations to activate the healable polymer matrix in areas of damage. The polymer matrix is a modified thermoset shape memory polymer that heals

  18. ADAPTIVE REFLEX CONTROL FOR AN ARTIFICIAL HAND

    Microsoft Academic Search

    Michele Folgheraiter; Giuseppina Gini; Marek Perkowski; Mikhail Pivtoraiko

    In this paper we illustrate the properties and the morphology of a human like neural reflex controller, used to set the stiness and joint positions of an anthropomorphic artificial hand. In particular we explain, by simulations results, its ability to emulate the myotatic human reflex, and its capacity to learn in real time the best control strategy. We also present

  19. Humanlike reflex control for an artificial hand

    Microsoft Academic Search

    Michele Folgheraiter; Giuseppina Gini

    2004-01-01

    In this paper, we illustrate the low level reflex control used to govern an anthropomorphic artificial hand. The paper develops the position and stiffness control strategy based on dynamic artificial neurons able to simulate the neurons acting in the human reflex control. The controller has a hierarchical structure. At the lowest level there are the receptors able to convert the

  20. Myotatic Reflex: Its Input-Output Relation

    Microsoft Academic Search

    R. E. Poppele; C. A. Terzuolo

    1968-01-01

    The dynamic properties of the myotatic reflex and of its components were determined by a systems-analysis approach. The gain and phase relations between an applied stretch, which initiates the reflex, and the output of the primary muscle spindles, which impinge upon alpha -motoneurons, are not further changed by the properties of the motoneurons. The dynamic relation between motoneuron activity and

  1. Reflexive autoepistemic logic and logic programming

    E-print Network

    Marek, Victor W.

    Reflexive autoepistemic logic and logic programming V. Wiktor Marek Miroslaw Truszczy@ms.uky.edu Abstract In this paper we show that reflexive autoepistemic logic of Schwarz is a par- ticularly convenient modal formalism for studying properties of answer sets for logic programs with classical negation

  2. Expression of the bilateral deficit during reflexively evoked contractions.

    PubMed

    Khodiguian, N; Cornwell, A; Lares, E; DiCaprio, P A; Hawkins, S A

    2003-01-01

    During maximal contractions, the sum of forces exerted by homonymous muscles unilaterally is typically larger than the sum of forces exerted by the same muscles bilaterally. This phenomenon is known as the bilateral deficit (BLD), and it is suggested that this deficit is due to neural inhibition. It remains unclear, however, whether such inhibition is mediated by supraspinal mechanisms or by reflex pathways at the level of spinal cord. To further study the origin of likely neural influences, we tested for the presence of BLD under the condition of reflexive force generation. Force output and integrated electromyogram (iEMG) (quadriceps femoris) were measured in 17 male participants after initiation of the myotatic patellar reflex under unilateral and bilateral conditions. A significant BLD of 9.26 +/- 1.19 (P = 0.004) and 16.76 +/- 4.69% (P = 0.001) was found for force and iEMG, respectively. However, because similar findings were not evident during maximal isometric knee extensions, it is difficult to predict the contribution of a spinal mechanism to the BLD under the condition of maximal voluntary activation. PMID:12391080

  3. Reliability of the NINDS Myotatic Reflex Scale.

    PubMed

    Litvan, I; Mangone, C A; Werden, W; Bueri, J A; Estol, C J; Garcea, D O; Rey, R C; Sica, R E; Hallett, M; Bartko, J J

    1996-10-01

    The assessment of deep tendon reflexes is useful for localization and diagnosis of neurologic disorders, but only a few studies have evaluated their reliability. We assessed the reliability of four neurologists, instructed in two different countries, in using the National Institute of Neurological Disorders and Stroke (NINDS) Myotatic Reflex Scale. To evaluate the role of training in using the scale, the neurologists randomly and blindly evaluated a total of 80 patients, 40 before and 40 after a training session. Inter- and intraobserver reliability were measured with kappa statistics. Our results showed substantial to near-perfect intraobserver reliability, and moderate-to-substantial interobserver reliability of the NINDS Myotatic Reflex Scale. The reproducibility was better for reflexes in the lower than in the upper extremities. Neither educational background nor the training session influenced the reliability of our results. The NINDS Myotatic Reflex Scale has sufficient reliability to be adopted as a universal scale. PMID:8857728

  4. TETANUS TOXIN REDUCES LOCAL AND DESCENDING REGULATION OF THE H-REFLEX

    PubMed Central

    MATTHEWS, CHRISTOPHER C.; FISHMAN, PAUL S.; WITTENBERG, GEORGE F.

    2015-01-01

    Introduction Skeletal muscles that are under the influence of tetanus toxin show an exaggerated reflex response to stretch. We examined which changes in the stretch reflex may underlie the exaggerated response. Methods H-reflexes were obtained from the tibialis anterior (TA) and flexor digitorum brevis (FDB) muscles in rats 7 days after intramuscular injection of tetanus toxin into the TA. Results We found effects of the toxin on the threshold, amplitude, and duration of H-waves from the TA. The toxin inhibited rate-dependent depression in the FDB between the stimulation frequencies of 0.5–50 HZ and when a conditioning magnetic stimulus applied to the brain preceded a test electrical stimulus delivered to the plantar nerve. Conclusions Tetanus toxin increased the amplitude of the H-wave and reduced the normal depression of H-wave amplitude that is associated with closely timed stimuli, two phenomena that could contribute to hyperactivity of the stretch reflex. PMID:24772492

  5. Achilles tendon reflex measuring system

    NASA Astrophysics Data System (ADS)

    Szebeszczyk, Janina; Straszecka, Joanna

    1995-06-01

    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.

  6. Laryngeal and respiratory protective reflexes.

    PubMed

    Altschuler, S M

    2001-12-01

    Swallowing is a complex motor behavior that relies on an interneuronal network of premotor neurons (PMNs) to organize the sequential activity of motor neurons that are active during the buccopharyngeal and esophageal phases. Swallowing PMNs are highly interconnected to multiple areas of the brain stem and the central nervous system and provide a potential anatomic substrate integration of swallowing activity with airway protective reflexes. Because these neurons have synaptic contact with both afferent inputs and motor neurons and exhibit a true central activity, they appear to constitute the swallowing central pattern generator. We studied the viscerotopic organization of the nucleus of the solitary tract (NTS), the nucleus ambiguus (NA), the dorsal motor nucleus (DMN), and the hypoglossal nucleus (XII) using cholera toxin horseradish peroxidase (CT-HRP), a sensitive antegrade and retrograde tracer that effectively labels afferent terminal fields within the NTS as well as swallowing motor neurons and their dendritic fields within the NA, DMN, and XII. We used CT-HRP to provide a comprehensive description of the dendritic architecture of NA motor neurons innervating swallowing muscles. We also conducted studies using pseudorabies virus (PRV), a swine alpha-herpesvirus, to map central neural circuits after injection in the peripheral or central nervous systems. One attenuated vaccine strain, Bartha PRV, has preferential affinity for sites of afferent synaptic contact on the cell body and dendrites and a reactive gliosis that effectively isolates the infected neurons and provides a barrier to the nonspecific spread to adjacent neurons. The findings provide a basis for the central integration of swallowing and respiratory protective reflexes. PMID:11749932

  7. Human myotatic reflex development of the lower extremities

    Microsoft Academic Search

    Charles T. Leonard; Tamaki Matsumoto; Pamela Diedrich

    1995-01-01

    Lower extremity (LE) myotatic reflexes were tested by percussion (taps) to the patellar and Achilles tendons. Surface electromyographic recordings were obtained from 5 LE muscles during tendon taps. Results indicated that LE myotatic reflexes underwent considerable change during early human development. The changes were non-linear and highly variable. Reflex irradiation (the presence of reflex responses in muscles other than the

  8. Implementation of an iPod wireless accelerometer application using machine learning to classify disparity of hemiplegic and healthy patellar tendon reflex pair

    PubMed Central

    LeMoyne, Robert; Kerr, Wesley T.; Zanjani, Kevin; Mastroianni, Timothy

    2014-01-01

    The characteristics of the patellar tendon reflex provide fundamental insight regarding the diagnosis of neurological status. Based on the features of the tendon reflex response, a clinician may establish preliminary perspective regarding the global condition of the nervous system. Current techniques for quantifying the observations of the reflex response involve the application of ordinal scales, requiring the expertise of a highly skilled clinician. However, the reliability of the ordinal scale approach is debatable. Highly skilled clinicians have even disputed the presence of asymmetric reflex pairs. An alternative strategy was the implementation of an iPod wireless accelerometer application to quantify the reflex response acceleration waveform. An application enabled the recording of the acceleration waveform and later wireless transmission as an email attachment by connectivity to the Internet. A potential energy impact pendulum enabled the patellar tendon reflex to be evoked in a predetermined and targeted manner. Three feature categories of the reflex response acceleration waveform (global parameters, temporal organization, and spectral features) were incorporated into machine learning to distinguish a subject's hemiplegic and healthy reflex pair. Machine learning attained perfect classification of the hemiplegic and healthy reflex pair. The research findings implicate the promise of machine learning for providing increased diagnostic acuity regarding the acceleration waveform of the tendon reflex response. PMID:25685611

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2014-08-15

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

  11. Diagnostic value of myotactic reflexes in axonal and demyelinating polyneuropathy.

    PubMed

    van Dijk, G W; Wokke, J H; Notermans, N C; van Gijn, J; Franssen, H

    1999-10-22

    In 11 patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and 11 patients with chronic idiopathic axonal polyneuropathy (CIAP), absent myotatic reflexes were significantly associated more often with CIDP than with CIAP, an absent biceps-reflex having the highest sensitivity and specificity for the diagnosis of CIDP. In CIDP, the latencies of electromyographically recorded myotatic reflexes often indicated demyelination, notwithstanding normal clinically assessed myotatic reflexes. Myotatic reflexes may therefore be useful for the distinction between axonal and demyelinating polyneuropathy. PMID:10534270

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

    PubMed

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

    1990-01-01

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

  13. A testbed for autonomous reflexive grasping

    NASA Astrophysics Data System (ADS)

    Kemme, David A.; McDonnell, John R.

    1993-03-01

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

  14. Reflexive Anaphora Resolution in Pashto Discourse

    Microsoft Academic Search

    Rahman Ali; Mohammad Abid Khan; Mushtaq Ali

    2009-01-01

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

  15. Variability in Hoffmann and tendon reflexes in healthy male subjects

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    There is a time dependent decrease in amplitude of H- and T-reflexes during Zero-G exposure and subsequently an increase in the amplitude of the H-reflex 2-4 hours after return to a 1-G environment. These alterations have been attributed to the adaptation of the human neurosensory system to gravity. The Hoffman reflex (H-reflex) is an acknowledged method to determine the integrity of the monosynaptic reflex arc. However deep tendon reflexes (DTR's or T-reflexes), elicited by striking the tendon also utilize the entire reflex arc. The objective of this study was to compare the variability in latency and amplitude of the two reflexes in healthy subjects. Methods: Nine healthy male subjects, 27-43 years in age, 161-175 cm in height plus 60-86 Kg in weight, underwent weekly testing for four weeks with a Dan-Tec EMG counterpoint EMG system. Subjects were studied prone and surface EMG electrodes were placed on the right and left soleus muscles. The H-reflex was obtained by stimulating the tibial nerve in the politeal fossa with a 0.2 msec square wave pulse delivered at 2 Hz until the maximum H-reflex was obtained. The T-reflex was invoked by tapping the achilles tendon with a self triggering reflex hammer connected to the EMG system. The latencies and amplitudes for the H- and T-reflexes were measured. Results: These data indicate that the amplitudes of these reflexes varied considerably. However, latencies to invoked responses were consistent. The latency of the T-reflex was approximately 3-5 msec longer than the H-reflex. Conclusion: The T-reflex is easily obtained, requires less time, and is more comfortable to perform. Qualitative data can be obtained by deploying self triggering, force plated reflex hammers both in the 1-G and Zero-G environment.

  16. Management of reflex anoxic seizures in children.

    PubMed

    Iyer, Anand; Appleton, Richard

    2013-09-01

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

  17. [Study of the H-reflex of human hand muscles using the post-stimulus histogram method].

    PubMed

    Person, R S

    1977-01-01

    The method of post-stimulus histograms of the single motor unit potentials permits the under-threshold facilitation to be revealed and the antidromic blocking of H-reflex to be avoided up to sub-maximal for M-response stimuli. The H-reflex was revealed only under abnormal conditions and was not observed in the noraml subjects. In the experiments the motoneurons responded to impulses from above, therefore the inhibition of the motoneurons itself cannot be a mechanism of the H-reflex inhibition. The alternative explanation is the presynaptic inhibition. PMID:593466

  18. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

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

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

    PubMed

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

    2015-01-01

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

  20. Loading and reflexes : the influence of body weight and active movements on reflex responses in humans

    Microsoft Academic Search

    Catharina Maria Bastiaanse

    2003-01-01

    This thesis describes six studies on the influence of active movements and body loading on reflex responses. To measure those influences healthy subjects were asked to walk with different loadings (e.g. a backpack) or with different active movements (e.g. arm swing) while different reflex responses were measured. After a general introduction (chapter 1), the studies are described. In chapter 2

  1. The trigeminocardiac reflex – a comparison with the diving reflex in humans

    PubMed Central

    Lemaitre, Frederic; Schaller, Bernhard

    2015-01-01

    The trigeminocardiac reflex (TCR) has previously been described in the literature as a reflexive response of bradycardia, hypotension, and gastric hypermotility seen upon mechanical stimulation in the distribution of the trigeminal nerve. The diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, reduction of limb blood flow and a gradual rise in the mean arterial blood pressure. Although the two reflexes share many similarities, their relationship and especially their functional purpose in humans have yet to be fully elucidated. In the present review, we have tried to integrate and elaborate these two phenomena into a unified physiological concept. Assuming that the TCR and the DR are closely linked functionally and phylogenetically, we have also highlighted the significance of these reflexes in humans. PMID:25995761

  2. Retrieval interference in reflexive processing: experimental evidence from Mandarin, and computational modeling

    PubMed Central

    Jäger, Lena A.; Engelmann, Felix; Vasishth, Shravan

    2015-01-01

    We conducted two eye-tracking experiments investigating the processing of the Mandarin reflexive ziji in order to tease apart structurally constrained accounts from standard cue-based accounts of memory retrieval. In both experiments, we tested whether structurally inaccessible distractors that fulfill the animacy requirement of ziji influence processing times at the reflexive. In Experiment 1, we manipulated animacy of the antecedent and a structurally inaccessible distractor intervening between the antecedent and the reflexive. In conditions where the accessible antecedent mismatched the animacy cue, we found inhibitory interference whereas in antecedent-match conditions, no effect of the distractor was observed. In Experiment 2, we tested only antecedent-match configurations and manipulated locality of the reflexive-antecedent binding (Mandarin allows non-local binding). Participants were asked to hold three distractors (animate vs. inanimate nouns) in memory while reading the target sentence. We found slower reading times when animate distractors were held in memory (inhibitory interference). Moreover, we replicated the locality effect reported in previous studies. These results are incompatible with structure-based accounts. However, the cue-based ACT-R model of Lewis and Vasishth (2005) cannot explain the observed pattern either. We therefore extend the original ACT-R model and show how this model not only explains the data presented in this article, but is also able to account for previously unexplained patterns in the literature on reflexive processing. PMID:26074829

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  4. Modulation of human vestibular reflexes with increased postural threat.

    PubMed

    Horslen, Brian C; Dakin, Christopher J; Inglis, J Timothy; Blouin, Jean-Sébastien; Carpenter, Mark G

    2014-08-15

    Anxiety and arousal have been shown to facilitate human vestibulo-ocular reflexes, presumably through direct neural connections between the vestibular nuclei and emotional processing areas of the brain. However, the effects of anxiety, fear and arousal on balance-relevant vestibular reflexes are currently unknown. The purpose of this study was to manipulate standing height to determine whether anxiety and fear can modulate the direct relationship between vestibular signals and balance reflexes during stance. Stochastic vestibular stimulation (SVS; 2-25 Hz) was used to evoke ground reaction forces (GRF) while subjects stood in both LOW and HIGH surface height conditions. Two separate experiments were conducted to investigate the SVS-GRF relationship, in terms of coupling (coherence and cumulant density) and gain, in the medio-lateral (ML) and antero-posterior (AP) directions. The short- and medium-latency cumulant density peaks were both significantly increased in the ML and AP directions when standing in HIGH, compared to LOW, conditions. Likewise, coherence was statistically greater between 4.3 Hz and 6.7 Hz in the ML, and between 5.5 and 17.7 Hz in the AP direction. When standing in the HIGH condition, the gain of the SVS-GRF relationship was increased 81% in the ML direction, and 231% in the AP direction. The significant increases in coupling and gain observed in both experiments demonstrate that vestibular-evoked balance responses are augmented in states of height-induced postural threat. These data support the possibility that fear or anxiety-mediated changes to balance control are affected by altered central processing of vestibular information. PMID:24973412

  5. Reflex sympathetic dystrophy: an enigmatic improvement with spinal manipulation

    PubMed Central

    Bortolotto, James

    2000-01-01

    Reflex Sympathetic Dystrophy (RSD) or complex regional pain syndrome, is an extremely painful and disabling condition commonly seen following trauma. Its early recognition and treatment is most critical for a favorable prognosis. Although its diagnosis and treatments vary, neuroblockade is the treatment of choice. Very little has been reported in the literature in regards to manipulation as an early treatment modality to improve joint mobility and reduce pain and future disability. This case report reviews one case presentation of RSD where dramatic results followed cervical spine manipulation.

  6. Proposed equation between flexor carpi radialis H-reflex latency and upper limb length

    PubMed Central

    Khosrawi, Saeid; Taheri, Parisa; Hashemi, Seyed Hasan

    2015-01-01

    Background: H-reflex is a valuable electrophysiological technique for assessing nerve conduction through entire length of afferent and efferent pathways, especially nerve roots and proximal segments of peripheral nerves. The aim of this study was to investigate the relation between normal values of flexor carpi radialis (FCR) H-reflex latency, upper limb length and age in normal subjects, and to determine whether there is any regression equation between them. Methods: By considering the criteria of inclusion and exclusion, 120 upper limbs of 69 normal volunteers (68 hands of 39 men and 52 hands of 30 women) with the mean age of 39.8 ± 11.2 years participated in this study. FCR H-reflex was obtained by standard electrodiagnostic techniques, and its onset latency was recorded. Upper limb length and arm length were measured in defined position. The degree of association between these variables was determined with Pearson correlation and linear regression was used for obtaining the proposed relations. Results: Mean FCR H-reflex latency was found to be 15.88 ± 1.27 ms. There was a direct linear correlation between FCR H-reflex latency and upper limb length (r = 0.647) and also arm length (r = 0.574), but there was no significant correlation between age and FCR H-reflex latency (P = 0.260). Finally, based on our findings, we tried to formulate these relations by statistical methods. Conclusion: We found that upper limb length and arm length are good predictive values for estimation of normal FCR H-reflex latency but age, in the range of 20-60 years old, has no correlation with its latency. This estimation could have practical indications in pathologic conditions. PMID:25874056

  7. Effects of postural threat on spinal stretch reflexes: evidence for increased muscle spindle sensitivity?

    PubMed

    Horslen, Brian C; Murnaghan, Chantelle D; Inglis, J Timothy; Chua, Romeo; Carpenter, Mark G

    2013-08-01

    Standing balance is often threatened in everyday life. These threats typically involve scenarios in which either the likelihood or the consequence of falling is higher than normal. When cats are placed in these scenarios they respond by increasing the sensitivity of muscle spindles imbedded in the leg muscles, presumably to increase balance-relevant afferent information available to the nervous system. At present, it is unknown whether humans also respond to such postural threats by altering muscle spindle sensitivity. Here we present two studies that probed the effects of postural threat on spinal stretch reflexes. In study 1 we manipulated the threat associated with an increased consequence of a fall by having subjects stand at the edge of an elevated surface (3.2 m). In study 2 we manipulated the threat by increasing the likelihood of a fall by occasionally tilting the support surface on which subjects stood. In both scenarios we used Hoffmann (H) and tendon stretch (T) reflexes to probe the spinal stretch reflex circuit of the soleus muscle. We observed increased T-reflex amplitudes and unchanged H-reflex amplitudes in both threat scenarios. These results suggest that the synaptic state of the spinal stretch reflex is unaffected by postural threat and that therefore the muscle spindles activated in the T-reflexes must be more sensitive in the threatening conditions. We propose that this increase in sensitivity may function to satisfy the conflicting needs to restrict movement with threat, while maintaining a certain amount of sensory information related to postural control. PMID:23719208

  8. Visual modulation of proprioceptive reflexes during movement

    PubMed Central

    Mutha, Pratik K.; Boulinguez, Philippe; Sainburg, Robert L.

    2009-01-01

    Previous research has demonstrated that feedback circuits such as reflexes can be tuned by setting their gains prior to movement onset during both posture and movement tasks. However, such a control strategy requires that perturbation contingencies be predicted during movement planning and that task goals remain fixed. Here we test the hypothesis that feedforward regulation of reflex circuits also occurs during the course of movement in response to changes in task goals. Participants reached to a visual target that was occasionally jumped on movement initiation, thus changing task goals. Reflex responses were elicited through a mechanical perturbation on the same trial, 100 milliseconds after the target jump. Impedance to the perturbation was tuned to the direction of the preceding jump: reflex responses increased or decreased depending on whether the perturbation opposed or was consistent with the target jump. This modulation, although sensitive to the direction of the jump, was insensitive to jump amplitude, as tested in a follow-up experiment. Our findings thus suggest that modulation of reflex circuits occurs online, and is sensitive to changes in visual target information. In addition, our results suggest a two-level model for visuo-motor control that reflects hierarchical neural organization. PMID:18926800

  9. Asymmetric tonic labyrinth reflexes and their interaction with neck reflexes in the decerebrate cat.

    PubMed Central

    Lindsay, K W; Roberts, T D; Rosenberg, J R

    1976-01-01

    1. Tonic labyrinth and neck reflexes were studied separately and in combination in the decerebrate cat with C1 and C2 spinal roots cut. Reflex effects were observed as changes in length of the isotonically loaded medial head of triceps. 2. The tonic labyrinth reflexes acted asymmetrically on the medial head of triceps. Side-down rotation of the head produced shortening in medial triceps, whereas side-up rotations of the head resulted in a lengthening. 3. The tonic neck reflexes acted asymmetrically on the medial head of triceps. Side-down rotations of the neck produced a lengthening of medial triceps, whereas side-up rotations of the neck resulted in shortening. 4. Labyrinth and neck reflexes produce opposite effects on the same limb extensor muscle so that, if the neck innervation is intact, head tilting produces no change in muscle length. 5. It is suggested that the interaction between the labyrinth and neck reflexes contributes to the stability of the trunk, allowing the head to move freely on the body without affecting this stability. Labyrinth and neck reflexes need therefore to be considered together as a single system. PMID:978589

  10. Biological motion cues trigger reflexive attentional orienting.

    PubMed

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

    2010-12-01

    The human visual system is extremely sensitive to biological signals around us. In the current study, we demonstrate that biological motion walking direction can induce robust reflexive attentional orienting. Following a brief presentation of a central point-light walker walking towards either the left or right direction, observers' performance was significantly better on a target in the walking direction compared with that in the opposite direction even when participants were explicitly told that walking direction was not predictive of target location. Interestingly, the effect disappeared when the walker was shown upside-down. Moreover, the reflexive attentional orienting could be extended to motions of other biological entities but not inanimate objects, and was not due to the viewpoint effect of the point-light figure. Our findings provide strong evidence that biological motion cues can trigger reflexive attentional orienting, and highlight the intrinsic sensitivity of the human visual attention system to biological signals. PMID:20883983

  11. Reflexive composites: self-healing composite structures

    NASA Astrophysics Data System (ADS)

    Margraf, Thomas W., Jr.; Barnell, Thomas J.; Havens, Ernie; Hemmelgarn, Christopher D.

    2008-03-01

    Cornerstone Research Group Inc. has developed reflexive composites achieving increased vehicle survivability through integrated structural awareness and responsiveness to damage. Reflexive composites can sense damage through integrated piezoelectric sensing networks and respond to damage by heating discrete locations to activate the healable polymer matrix in areas of damage. The polymer matrix is a modified thermoset shape memory polymer that heals based on phenomena known as reptation. In theory, the reptation healing phenomena should occur in microseconds; however, during experimentation, it has been observed that to maximize healing and restore up to 85 % of mechanical properties a healing cycle of at least three minutes is required. This paper will focus on work conducted to determine the healing mechanisms at work in CRG's reflexive composites, the optimal healing cycles, and an explanation of the difference between the reptation model and actual healing times.

  12. On the Classification of Reflexive Polyhedra

    NASA Astrophysics Data System (ADS)

    Kreuzer, M.; Skarke, H.

    Reflexive polyhedra encode the combinatorial data for mirror pairs of Calabi-Yau hypersurfaces in toric varieties. We investigate the geometrical structures of circumscribed polytopes with a minimal number of facets and of inscribed polytopes with a minimal number of vertices. These objects, which constrain reflexive pairs of polyhedra from the interior and the exterior, can be described in terms of certain non-negative integral matrices. A major tool in the classification of these matrices is the existence of a pair of weight systems, indicating a relation to weighted projective spaces. This is the cornerstone for an algorithm for the construction of all dual pairs of reflexive polyhedra that we expect to be efficient enough for an enumerative classification in up to 4 dimensions, which is the relevant case for Calabi-Yau compactifications in string theory.

  13. Neural reflexes in inflammation and immunity

    PubMed Central

    2012-01-01

    The mammalian immune system and the nervous system coevolved under the influence of infection and sterile injury. Knowledge of homeostatic mechanisms by which the nervous system controls organ function was originally applied to the cardiovascular, gastrointestinal, musculoskeletal, and other body systems. Development of advanced neurophysiological and immunological techniques recently enabled the study of reflex neural circuits that maintain immunological homeostasis, and are essential for health in mammals. Such reflexes are evolutionarily ancient, dating back to invertebrate nematode worms that possess primitive immune and nervous systems. Failure of these reflex mechanisms in mammals contributes to nonresolving inflammation and disease. It is also possible to target these neural pathways using electrical nerve stimulators and pharmacological agents to hasten the resolution of inflammation and provide therapeutic benefit. PMID:22665702

  14. On the Classification of Reflexive Polyhedra

    E-print Network

    M. Kreuzer; H. Skarke

    1997-02-04

    Reflexive polyhedra encode the combinatorial data for mirror pairs of Calabi-Yau hypersurfaces in toric varieties. We investigate the geometrical structures of circumscribed polytopes with a minimal number of facets and of inscribed polytopes with a minimal number of vertices. These objects, which constrain reflexive pairs of polyhedra from the interior and the exterior, can be described in terms of certain non-negative integral matrices. A major tool in the classification of these matrices is the existence of a pair of weight systems, indicating a relation to weighted projective spaces. This is the corner stone for an algorithm for the construction of all dual pairs of reflexive polyhedra that we expect to be efficient enough for an enumerative classification in up to 4 dimensions, which is the relevant case for Calabi-Yau compactifications in string theory.

  15. A reflex resonance model of vocal vibrato

    NASA Astrophysics Data System (ADS)

    Titze, Ingo R.; Story, Brad; Smith, Marshall; Long, Russel

    2002-05-01

    A reflex mechanism with a long latency (>40 ms) is implicated as a plausible cause of vocal vibrato. At least one pair of agonist-antagonist muscles that can change vocal-fold length is needed, such as the cricothyroid muscle paired with the thyroarytenoid muscle, or the cricothyroid muscle paired with the lateral cricoarytenoid muscle or a strap muscle. Such an agonist-antagonist muscle pair can produce negative feedback instability in vocal-fold length with this long reflex latency, producing oscillations on the order of 5-7 Hz. It is shown that singers appear to increase the gain in the reflex loop to cultivate the vibrato, which grows out of a spectrum of 0-15-Hz physiologic tremors in raw form.

  16. Classification of Reflexive Polyhedra in Three Dimensions

    E-print Network

    M. Kreuzer; H. Skarke

    1998-05-27

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

  17. Nasal reflexes: Implications for exercise, breathing, and sex

    Microsoft Academic Search

    James N. Baraniuk; Samantha J. Merck

    2008-01-01

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

  18. Monitoring of head injury by myotatic reflex evaluation

    Microsoft Academic Search

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

    2000-01-01

    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

  19. A SERVOANALYTIC STUDY OF CONSENSUAL PUPIL REFLEX TO LIGHT1

    E-print Network

    Catholique de Louvain, Université

    in terms of servotheory to the silent- period phenomenon of the myotatic reflex (11, 12). In anotherA SERVOANALYTIC STUDY OF CONSENSUAL PUPIL REFLEX TO LIGHT1 LAWRENCE STARK AND PHILIP M. SHERMAN reflex to light is an example of such a process. This paper approaches the problem of a quantitative

  20. Reflex control of the prototype leg during contact and slippage

    Microsoft Academic Search

    Ho Cheung Wong; David E. Orin

    1988-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Komendantov, G. L.

    1973-01-01

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

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

    PubMed

    McCormick, Lillian R; Cohen, Jonathan H

    2012-08-01

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

  3. An architecture for reflexive autonomous vehicle control

    Microsoft Academic Search

    David W. Payton

    1986-01-01

    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

  4. Biological Motion Cues Trigger Reflexive Attentional Orienting

    ERIC Educational Resources Information Center

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

    2010-01-01

    The human visual system is extremely sensitive to biological signals around us. In the current study, we demonstrate that biological motion walking direction can induce robust reflexive attentional orienting. Following a brief presentation of a central point-light walker walking towards either the left or right direction, observers' performance…

  5. Perspective on the human cough reflex

    PubMed Central

    2011-01-01

    This review dissects the complex human cough reflex and suggests hypotheses about the evolutionary basis for the reflex. A mechanosensory-induced cough reflex conveys through branches of myelinated A? nerve fibers is not chemically reactive (i.e., capsaicin, bradykinin); possibly, its evolution is to prevent the harmful effects of aspiration of gastric or particulate contents into the lungs. This became necessary as the larynx moves closer to the opening of the esophagus as human ancestors adapt phonation over olfaction beginning less than 10 million years ago. The second type of cough reflex, a chemosensory type, is carried by unmyelinated C fibers. Supposedly, its origin dates back when prehistoric humans began living in close proximity to each other and were at risk for infectious respiratory diseases or irritant-induced lung injury. The mechanism for the latter type of cough is analogous to induced pain after tissue injury; and, it is controlled by the identical transient receptor potential vanilloid cation channel (TRPV1). The airways do not normally manifest nociceptive pain from a stimulus but the only consistent response that capsaicin and lung inflammation provoke in healthy human airways is cough. TRPA1, another excitatory ion channel, has been referred to as the "irritant receptor" and its activation also induces cough. For both types of cough, the motor responses are identical and via coordinated, precisely-timed and sequential respiratory events orchestrated by complex neuromuscular networking of the diaphragm, chest and abdominal respiratory muscles, the glottis and parts of the brain. PMID:22074326

  6. Research report Elevated depressive symptoms enhance reflexive

    E-print Network

    Maddox, W. Todd

    Research report Elevated depressive symptoms enhance reflexive but not reflective auditory category efficiency of the two learning systems. Previous studies have shown that individuals with elevated depressive are dissociable and competitive. We predicted that elevated depressive symptoms would lead to reflective

  7. Jaw reflexes in healthy old people

    Microsoft Academic Search

    ANASTASSIA E. KOSSIONI; HERCULES C. KARKAZIS

    1998-01-01

    Objective: to investigate variations in the masseteric myotatic reflex (jaw-jerk) and the silent period from the 5th to the 9th decades of life. Subjects and methods: electromyographic data were recorded from the masseter muscle of the preferred chewing side by surface electrodes, using a computerized recording and analysis system. Chin taps were applied with a neurologist's hammer during mandibular rest

  8. Reflex Anuria After Renal Tumor Embolization

    SciTech Connect

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

    2007-04-15

    We report a case of reflex anuria after transarterial embolization of a renal tumor. Anuria developed immediately after embolization and resolved 74 hr following the procedure. We postulate that reflux anuria in our case was related to mechanoreceptors, chemoreceptors, or both, as these are stimulated by the occluded blood vessels, ischemia, and edema of the normal renal tissue of an embolized kidney.

  9. Reflex sympathetic dystrophy: changing concepts and taxonomy

    Microsoft Academic Search

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

    1995-01-01

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

  10. Is human galvanically induced triceps surae electromyogram a vestibulospinal reflex response?

    PubMed

    Storper, I S; Honrubia, V

    1992-10-01

    Interest in understanding the human vestibulospinal reflex has increased enormously over the past three decades, because this reflex is the primary effector of maintenance of posture and balance. On a posture platform, forces exerted by the triceps surae (TS) and tibialis anterior muscles are measured to calculate center of mass sway. We wished to determine whether the TS response is a direct component of the vestibulospinal reflex. Ten healthy human beings were stimulated with sinusoidal galvanic currents delivered over their mastoid processes. Sway response on a posture platform and TS electromyogram (EMG) were recorded for the following conditions: (1) standing unrestrained; (2) standing completely restrained above the leg; and (3) sitting unrestrained. Results were similar for all subjects. Computer-aided analysis for case 1 reveals that TS EMG and horizontal body sway responses are generated at the same frequency as the stimulating current, with a phase lag of 90 degrees. For case 2, body sway response and any component of the TS EMG over the unstimulated condition were absent in all subjects. For case 3, body sway persisted, but no TS EMG above the unstimulated condition was recorded. As the TS EMG disappears when the standing subject is restrained from swaying or in the unrestrained seated subject, we conclude that the TS EMG response is compensatory to motion of more superior portions of the musculoskeletal system; it is not part of the vestibulospinal reflex. PMID:1437184

  11. Specificity of Reflex Adaptation for Task-Relevant Variability

    PubMed Central

    Franklin, David W.; Wolpert, Daniel M.

    2009-01-01

    The motor system responds to perturbations with reflexes, such as the vestibulo-ocular reflex or stretch reflex, whose gains adapt in response to novel and fixed changes in the environment, such as magnifying spectacles or standing on a tilting platform. Here we demonstrate a reflex response to shifts in the hand’s visual location during reaching, which occurs before the onset of voluntary reaction time, and investigate how its magnitude depends on statistical properties of the environment. We examine the change in reflex response to two different distributions of visuomotor discrepancies, both of which have zero mean and equal variance across trials. Critically one distribution is task-relevant and the other task-irrelevant. The task-relevant discrepancies are maintained to the end of the movement, whereas the task-irrelevant discrepancies are transient such that no discrepancy exists at the end of the movement. The reflex magnitude was assessed using identical probe trials under both distributions. We find opposite directions of adaptation of the reflex response under these two distributions, with increased reflex magnitudes for task relevant variability and decreased reflex magnitudes for task irrelevant variability. This demonstrates modulation of reflex magnitudes in the absence of a fixed change in the environment, and shows that reflexes are sensitive to the statistics of tasks with modulation depending on whether the variability is task-relevant or task-irrelevant. PMID:19109499

  12. Modulation of the initial light reflex during affective picture viewing.

    PubMed

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

    2014-09-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  15. Influence of Age on Patellar Tendon Reflex Response

    PubMed Central

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

    2013-01-01

    Background A clinical parameter commonly used to assess the neurological status of an individual is the tendon reflex response. However, the clinical method of evaluation often leads to subjective conclusions that may differ between examiners. Moreover, attempts to quantify the reflex response, especially in older age groups, have produced inconsistent results. This study aims to examine the influence of age on the magnitude of the patellar tendon reflex response. Methodology/Principal Findings This study was conducted using the motion analysis technique with the reflex responses measured in terms of knee angles. Forty healthy subjects were selected and categorized into three different age groups. Patellar reflexes were elicited from both the left and right patellar tendons of each subject at three different tapping angles and using the Jendrassik maneuver. The findings suggested that age has a significant effect on the magnitude of the reflex response. An angle of 45° may be the ideal tapping angle at which the reflex can be elicited to detect age-related differences in reflex response. The reflex responses were also not influenced by gender and were observed to be fairly symmetrical. Conclusions/Significance Neurologically normal individuals will experience an age-dependent decline in patellar reflex response. PMID:24260483

  16. Is MS Intention Tremor Amplitude Related to Changed Peripheral Reflexes?

    PubMed Central

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

    2011-01-01

    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. PMID:22389808

  17. Modulation of the myotatic reflex gain in man during intentional movements.

    PubMed

    Dufresne, J R; Soechting, J F; Terzuolo, C A

    1980-07-01

    Human subjects were asked to perform sinusoidal tracking movements (0.5--3.0 Hz) with their forearms while external torque disturbances were applied at the elbow. The changes in angular position, velocity, and acceleration produced by these disturbances were found to be represented in the reflex changes in EMG activity of both biceps and triceps muscles. The gain of each of these reflex components varied during the tracking task, their maximal being about the same as those measured when the torque disturbances were applied in the absence of movements and the subjects attempted to maintain a constant forearm position. Such changes in gain were found to be centrally regulated since they were shown not to depend on the movement itself, being also present during force tracking, i.e. under nearly isometric conditions. Also their minima and maxima did not coincide with those of the EMG activity. These results suggest that an internal plan (or model) of the learned task is present, whereby reflex gains can be regulated independently from the motion and alpha-motoneuron activity. Such regulation effectively uncouples the reflex motor output from the intentionally controlled motion and maintains spindle sensitivity to external disturbances independent of large changes in muscle length. These conclusions are discussed in the context of the functional role of gamma-motoneurons in the control of movements. PMID:7378830

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

    PubMed Central

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

    2012-01-01

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

  19. Context-Specific Adaptation of Gravity-Dependent Vestibular Reflex Responses

    NASA Technical Reports Server (NTRS)

    Shelhamer, Mark J.

    1999-01-01

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

  20. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...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...

  1. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...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...

  2. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...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...

  3. Excitability of the soleus H-reflex arc during walking and stepping in man.

    PubMed

    Crenna, P; Frigo, C

    1987-01-01

    In eight normal subjects, the excitability of the soleus (Sol) H-reflex was tested in parallel with Sol length changes, EMGs of leg and thigh muscles and ground contact phases, during three different pacing movements: bipedal treadmill walking, single limb treadmill walking, and single-limb stepping on one spot. A computerized procedure was used which compensated for changes in stimulus effectiveness that occurred during free motion. In the three paradigms examined, significant excitability modulations were observed with respect to a control level determined in standing weight-bearing position. During bipedal treadmill walking, excitability was decreased in the early stance, maximally enhanced in the second half of the stance, and again decreased during the end-stance and the whole swing phase, with a minimum value around the toe off period. The main modulation pattern was retained during single-limb treadmill walking. During single-limb stepping on one spot, the stance-phase increase in excitability and the swing phase depression were still present. However, in the second half of the swing phase, reflex responsiveness returned to reference level, which was maintained during the subsequent contact period. Moreover, a decrease in reflex excitability was detected around the mid-stance. The time course of the described modulations was only partly correlated with the EMG and length changes of the Sol muscle. Furthermore, in the three movements tested, during the early stance phase, the excitability of the H-reflex arc did not correspond to the one expected on the basis of the available H-reflex studies performed under static conditions. It is suggested that, at least in certain stride phases (e.g. around the early contact period), an active regulation affects the transmission in the Sol myotatic arc during the pacing movements investigated. PMID:3582535

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

    ERIC Educational Resources Information Center

    Raven, Glenda

    2006-01-01

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

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

    ERIC Educational Resources Information Center

    Dyke, Martin

    2009-01-01

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

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    PubMed

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

    2014-01-01

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

  8. Bidirectional interactions between the baroreceptor reflex and arousal: an update.

    PubMed

    Silvani, Alessandro; Calandra-Buonaura, Giovanna; Benarroch, Eduardo E; Dampney, Roger A L; Cortelli, Pietro

    2015-02-01

    Studies involving genetic engineering on animal models and mathematical analysis of cardiovascular signals on humans are shedding new light on the interactions between the arterial baroreceptor reflex (baroreflex) and arousal. Baroreceptor stimulation, if very mild or performed under anaesthesia, may inhibit cortical arousal. However, substantial increases or decreases in baroreflex activation cause arousal in animal models and human subjects in physiological conditions. On the other hand, cardiovascular changes during autonomic arousals and between the states of wakefulness and sleep involve changes in the baroreflex set point and balance with central autonomic commands. Neural connectivity and functional data suggest that the nucleus of the solitary tract, adrenergic C1 neurons of the medulla, and the parabrachial nucleus of the pons mediate the bidirectional interactions between the baroreflex and arousal. These interactions may constitute a positive feedback loop that facilitates sharp and coordinated brain state and autonomic transitions upon arousal: upon arousal, central autonomic commands may increase blood pressure, thereby loading baroreceptors and further increasing arousal. Anomalies of this feedback loop may play a role in the pathophysiology of disease conditions associated with cardiovascular and sleep-wake cycle alterations. These conditions include: obstructive sleep apnoea syndrome, with its association with excessive daytime sleepiness and baroreflex impairment; and insomnia, with its association with autonomic hyperarousal and hypertension. When faced with disorders associated with cardiovascular and sleep-wake cycle alterations, clinical reasoning should entertain the possibility that both conditions are strongly influenced by anomalies of baroreflex function. PMID:25616389

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

    PubMed Central

    2011-01-01

    Background Insight is impaired in a majority of people with schizophrenia. Impaired insight is associated with poorer outcomes of the disorder. Based on existing literature, we developed a model that explains which processes may possibly play a role in impaired insight. This model was the starting point of the development of REFLEX: a brief psychosocial intervention to improve insight in schizophrenia. REFLEX is a 12-sessions group training, consisting of three modules of four sessions each. Modules in this intervention are: "coping with stigma", "you and your personal narrative", and "you in the present". Methods/Design REFLEX is currently evaluated in a multicenter randomized controlled trial. Eight mental health institutions in the Netherlands participate in this evaluation. Patients are randomly assigned to either REFLEX or an active control condition, existing of cognitive remediation exercises in a group. In a subgroup of patients, fMRI scans are made before and after training in order to assess potential haemodynamic changes associated with the effects of the training. Discussion REFLEX is one of the few interventions aiming specifically to improving insight in schizophrenia and has potential value for improving insight. Targeting insight in schizophrenia is a complex task, that comes with several methodological issues. These issues are addressed in the discussion of this paper. Trial registration Current Controlled Trials: ISRCTN50247539 PMID:21975132

  10. The proboscis extension reflex not elicited in Magachilid bees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Honey bees (Apis mellifera L.) will reflexively extend their proboscis in response to antennal stimulation with sucrose solution. For decades, the proboscis extension reflex (PER) of honey bees has been used as a tool to further the understanding of their cognitive processes, such as learning and m...

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

    E-print Network

    Johnson, William B.

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

  12. Reflex HMD to Compensate Lag and Correction of Derivative Deformation

    Microsoft Academic Search

    Ryugo Kijima; Takeo Ojika

    2002-01-01

    A head-mounted display (HMD) system suffers largely from the time lag between human motion and the display output. The concept of a reflex HMD to compensate for the time lag is proposed and discussed. Based on this notion, a prototype reflex HMD is constructed. The rotational movement of the user's head is measured by a gyroscope, modulating the driving signal

  13. Reflexivity of Discomfort in Insider-Outsider Educational Research

    ERIC Educational Resources Information Center

    Hamdan, Amani K.

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  15. Regulation of reflex gain in the control of movement

    Microsoft Academic Search

    Gerald L. Gottlieb; Gyan C. Agarwal

    1981-01-01

    The myotatic reflex, the simplest and fastest feedback loop of the motor system has not been demonstrated to possess a clear and simple physiological role in motor control. In this paper, we discuss two possible roles, load compensation and sensory-motor integration. Integral to both these roles is the idea that the gain of the closed-loop reflex arc is one of

  16. A simple measurement hammer for quantitative reflex studies.

    PubMed

    Stam, J; Van Leeuwen, J R

    1984-09-01

    A reflex hammer for measurement of the mechanical stimulus strength was designed. Combined with standard EMG equipment this instrument permits the study of both stimulus-response relations and latencies of myotatic reflexes. Some results in normal subjects are discussed. PMID:6205860

  17. A method of study of the human myotatic reflex

    Microsoft Academic Search

    Z. A. Gantseva

    1962-01-01

    The results obtained by the method of equitonometry in measuring the myotatic reflex in man are described. Besides recording the responses mechanically as suggested by G. V. Dzhikiya [1, 2] a control was made by recording the electromyogram. A determination was made of the mean reflex time, and of its correlation with the strength of the stimulus; both flexors and

  18. Reflexive Management Learning: An Integrative Review and a Conceptual Typology

    ERIC Educational Resources Information Center

    Cotter, Richard J.; Cullen, John G.

    2012-01-01

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

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

    PubMed

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

    2013-08-01

    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

  20. Conditions?

    Microsoft Academic Search

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

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

  1. Is the long-latency stretch reflex in human masseter transcortical?

    PubMed

    Pearce, Sophie L; Miles, Timothy S; Thompson, Philip D; Nordstrom, Michael A

    2003-06-01

    A long-latency stretch reflex (LLSR) has been described in the human masseter muscle, but its pathway remains uncertain. To investigate this, the excitability of corticomotoneuronal (CM) cells projecting to masseter motoneurons during the LLSR was assessed with transcranial magnetic stimulation (TMS). A facilitated response to TMS would be evidence of a LLSR pathway that traverses the motor cortex. Surface electromyogram electrodes were placed over the left or right masseter, and subjects ( n=10) bit on bars with their incisor teeth at 10% of maximal electromyographic activity (EMG). Servo-controlled displacements were imposed on the lower jaw to evoke a short- and long-latency stretch reflex in masseter. TMS intensity was just suprathreshold for a response in contralateral masseter. Trials consisted of: (1) stretch alone, (2) TMS alone, and (3) TMS with a preceding conditioning stretch at varied conditioning-testing (C-T) intervals chosen to combine TMS with the short-latency stretch reflex (3 ms, 5 ms) and the LLSR (23-41 ms). Masseter EMG was rectified and averaged. With TMS alone, mean (+/- SE) MEP area above baseline was 56+/-9%. The area of masseter MEPs above baseline in the C-T trials was calculated from each EMG average following subtraction of the response to stretch alone. Conditioning muscle stretch had no significant effect on masseter MEPs evoked by TMS with any C-T interval (ANOVA; P=0.90). In addition, subjects were unable to modify the SLSR or LLSR by voluntary command. It is concluded that the long-latency stretch reflex in the masseter does not involve the motor cortex and is not influenced by "motor set". PMID:12712307

  2. Resuscitation and auto resuscitation by airway reflexes in animals

    PubMed Central

    2013-01-01

    Various diseases often result in decompensation requiring resuscitation. In infants moderate hypoxia evokes a compensatory augmented breath – sigh and more severe hypoxia results in a solitary gasp. Progressive asphyxia provokes gasping respiration saving the healthy infant – autoresuscitation by gasping. A neonate with sudden infant death syndrome, however, usually will not survive. Our systematic research in animals indicated that airway reflexes have similar resuscitation potential as gasping respiration. Nasopharyngeal stimulation in cats and most mammals evokes the aspiration reflex, characterized by spasmodic inspiration followed by passive expiration. On the contrary, expiration reflex from the larynx, or cough reflex from the pharynx and lower airways manifest by a forced expiration, which in cough is preceded by deep inspiration. These reflexes of distinct character activate the brainstem rhythm generators for inspiration and expiration strongly, but differently. They secondarily modulate the control mechanisms of various vital functions of the organism. During severe asphyxia the progressive respiratory insufficiency may induce a life-threatening cardio-respiratory failure. The sniff- and gasp-like aspiration reflex and similar spasmodic inspirations, accompanied by strong sympatho-adrenergic activation, can interrupt a severe asphyxia and reverse the developing dangerous cardiovascular and vasomotor dysfunctions, threatening with imminent loss of consciousness and death. During progressive asphyxia the reversal of gradually developing bradycardia and excessive hypotension by airway reflexes starts with reflex tachycardia and vasoconstriction, resulting in prompt hypertensive reaction, followed by renewal of cortical activity and gradual normalization of breathing. A combination of the aspiration reflex supporting venous return and the expiration or cough reflex increasing the cerebral perfusion by strong expirations, provides a powerful resuscitation and autoresuscitation potential, proved in animal experiments. They represent a simple but unique model tested in animal experiments. PMID:23968541

  3. Stretch reflexes and joint dynamics in rheumatoid arthritis.

    PubMed

    Rajagopalan, Aparna; Burne, John A

    2010-02-01

    In clinically diagnosed rheumatoid arthritis (RA), studies were conducted to investigate the reflex and passive tissue contribution to measured increases in joint stiffness in the resting upper limb and during constant contractions of an attached muscle. The tonic stretch reflex was induced by a servo-controlled sinusoidal stretch perturbation of the metacarpophalangeal joint of RA patients, and age- and sex-matched controls. The resulting reflexes and mechanical changes in the RA affected joint were explored. Surface electromyographic (EMG) measurements were obtained from first dorsal interosseus muscle. Reflex gain (EMG/joint angle amplitude ratio), phase difference (reflex delay after stretch), coherence square (proportion of EMG variance accounted for by joint angle changes), joint mechanical gain (torque-joint angle amplitude ratio) and mechanical phase difference (torque response delay after stretch) were determined. RA patients showed decreased reflex gain that was partly due to coexistent severe muscle weakness, as determined from maximum voluntary contraction and grip pressure estimates. The decreased reflex gain was most evident at high stretch frequency suggesting a disproportionate loss of the large diameter afferent response and also increased reflex delay in the patients. These changes ensemble suggest significant loss of neural drive to the motor unit population. Patients also showed increased joint stiffness (measured as torque gain) in the contracting muscle, but there was no evidence of reflex activity or increased stiffness at rest. This suggests that the increased joint stiffness in RA was due to changes in the mechanical properties of the active muscle-joint system rather than changes in reflex properties. PMID:19771418

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

    Microsoft Academic Search

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

    1985-01-01

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

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

    PubMed

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

    2012-08-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    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. .

  7. Acoustic Startle Reflex and Prepulse Inhibition.

    PubMed

    Ouagazzal, Abdel Mottalib; Meziane, Hamid

    2012-01-01

    The completion of genome sequencing in humans and mice has opened new opportunities to study the relationship between gene expression and behavior and for development of novel therapeutic approaches for brain diseases. Recently, several international programs for large-scale production and phenotyping of genetically modified mice have been launched (e.g., EUCOMM, EUMODIC, IMPC), and comprehensive high-throughput behavioral phenotyping strategies have been developed (EUMORPHIA). In this context, startle reflex represents an important research tool for studying the impact of genetic manipulations not only on sensory processes but also on complex brain functions such as cognition, emotions, and movement control. In this unit, step-by-step protocols for measurement of acoustic startle reactivity and prepulse inhibition of startle in mice are described, and supporting experimental data presented. Curr. Protoc. Mouse Biol. 2:25-35 © 2012 by John Wiley & Sons, Inc. PMID:26069003

  8. Did reflexive catalysts drive chemical evolution?

    PubMed

    Allen, G

    1994-02-01

    High-energy starting materials and energy sources on the primitive earth would have generated abundant and varied organic molecules of small or medium size. It is questionable, however, whether ordinary chemical evolution could have produced information-carrying polymers. The end point might have been a fixed steady state if some form of autocatalysis had not intervened. Autocatalytic synthesis is possible for small molecules as illustrated by the formose reaction, in which glycolaldehyde condenses with formaldehyde to form sugars, and resulting tetroses may cleave into two molecules of glycolaldehyde. This and other 'reflexive catalysts', some functioning in molecular aggregates, may have energized chemical evolution and carried it to a level at which RNA or an RNA analog could replicate itself. PMID:7510381

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

    PubMed

    Bach, Dominik R

    2015-04-01

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

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

    PubMed

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

    2010-08-01

    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

  11. Modulation of slow and fast elbow extensor EMG tonic activity by stretch reflexes in man.

    PubMed

    Bejaoui, K; Le Bozec, S; Maton, B

    1987-01-01

    Reflex EMG responses to sudden passive flexion of the elbow were recorded from anconeus and triceps brachii in 5 human volunteers. While the subjects were required not to resist the flexion movement, they were required to maintain an extension torque of 3.5 or 7.0 Nm prior to its onset. Under these isotonic conditions, the latency and amplitude of the reflex activities from anconeus and triceps brachii did not differ significantly, in contrast to the findings of Le Bozec (1986) in actively relaxed subjects. The myotatic/postmyotatic EMG amplitude ratio did not provide a further quantitative way to distinguish between these muscles. The absence of a difference between the reflex activities of a slow (anconeus) and a fast (triceps brachii) muscle is interpreted as resulting from a strong drive of spindle activity on the whole extensor motoneuron pool, which outweights the differences in recruitment due to the differing relative amounts of type I and type II fibres in the two muscles. Differences like those described between finger and calf muscles by other authors are thought to be due to the relative degree of corticalization of these muscles. All short and long latency responses of the muscles increased in magnitude and decreased in latency with increasing background EMG activity as well as with increasing initial length. The position and tonic activity dependency of these responses is explained in terms of alpha-gamma coactivation. PMID:3830149

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

    PubMed Central

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

    2013-01-01

    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

  13. Non-reflexive Logical Foundation for Quantum Mechanics

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    On the one hand, non-reflexive logics are logics in which the principle of identity does not hold in general. On the other hand, quantum mechanics has difficulties regarding the interpretation of `particles' and their identity, also known in the literature as `the problem of indistinguishable particles'. In this article, we will argue that non-reflexive logics can be a useful tool to account for such quantum indistinguishability. In particular, we will provide a particular non-reflexive logic that can help us to analyze and discuss this problem. From a more general physical perspective, we will also analyze the limits imposed by the orthodox quantum formalism to consider the existence of indistinguishable particles in the first place, and argue that non-reflexive logics can also help us to think beyond the limits of classical identity.

  14. Speech Performance, Dysphagia and Oral Reflexes in Cerebral Palsy.

    ERIC Educational Resources Information Center

    Love, Russell J.; And Others

    1980-01-01

    The adequacy of biting, sucking, swallowing, and chewing as well as the presence or absence of nine infantile oral reflexes were assessed in 60 cerebral palsied individuals (ages 3 to 23). (Author/PHR)

  15. Reflexive Research Ethics in Fetal Tissue Xenotransplantation Research

    PubMed Central

    Panikkar, Bindu; Smith, Natasha; Brown, Phil

    2013-01-01

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

  16. 21 CFR 890.1450 - Powered reflex hammer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...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...

  17. LEARNING REFLEXES FOR TELEOPERATED GROUND-BASED RESCUE ROBOTS 

    E-print Network

    Moss, Matthew 1987-

    2011-04-25

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

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

    PubMed Central

    Tokuda, Keita; Nishikawa, Michimasa; Kawahara, Shigenori

    2014-01-01

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

  19. Reflex regulation during sustained and intermittent submaximal contractions in humans

    PubMed Central

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

    2002-01-01

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

  20. The development of reflexes and behavior in the rabbit 

    E-print Network

    Finn, Miguelita Whelan

    1977-01-01

    THE DEVELOPMFNT OF REFLEXES AND BEHAVIOR IN THE RABBIT A Thesis by MIGUELITA WHELAN FINN Submitted to the Graduate College of Texas AAM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1977... Major Subject: Veterinary Anatomy THE DEVELOPMENT OF REFLEXES AND BEHAVIOR IN THE RABBIT A Thesis by MIGUELITA WHELAN FINN Approved as to style and content by: (Chairman of Committee) (Head of Department) t (Member) ( mber August 1977...

  1. Mechanical Characteristics of Reflex Durign Upright Posture in Paralyzed Subjects

    NASA Astrophysics Data System (ADS)

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

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

  2. Human myotatic reflex development of the lower extremities.

    PubMed

    Leonard, C T; Matsumoto, T; Diedrich, P

    1995-08-30

    Lower extremity (LE) myotatic reflexes were tested by percussion (taps) to the patellar and Achilles tendons. Surface electromyographic recordings were obtained from 5 LE muscles during tendon taps. Results indicated that LE myotatic reflexes underwent considerable change during early human development. The changes were non-linear and highly variable. Reflex irradiation (the presence of reflex responses in muscles other than the one being directly stimulated by a tendon tap) was present in the newborn but to a lesser extent than was in evidence later on during the first year of life. The percentage of time reflex irradiation was detected in heteronymous muscle groups appeared to achieve maximal levels during the first year and then progressively decline. The decline in reflex irradiation was most dramatic between the first and second years of life. Irradiated responses were still recorded from 2 year-old children but with less frequency than in children less than 1 year of age. With the exception of responses in muscles that were direct antagonists to the stimulated muscle, irradiation was not observed in children 3-5 years of age. PMID:8575354

  3. A new technique to investigate vestibulo-spinal reflexes.

    PubMed

    Grasso, C; Orsini, P; Bruschini, L; Manzoni, D; Barresi, M

    2013-06-01

    Vestibulospinal reflexes can be elicited in humans by low amplitudes direct (galvanic) currents lasting tens of milliseconds and applied across the two mastoids bones, which can be delivered by particular stimulators. The stimulus induces a perception of body sway and a postural response appropriate to counteract the perceived sway. Both the direction of the perceived and induced body sway are modulated by the orientation of the head with respect to the body. This phenomenon is due to the fact that integration of vestibular and neck signals allows to correctly infer the direction of body sway from the labyrinthine input, which is instead related to direction of head motion. The modulation of stimulus-elicited body sway by neck rotation could be utilised for testing the effectiveness of neck proprioceptive signals in modifying the reference frame for labyrinthine signals from the head to the body. In the present experiments we showed that labyrinthine stimulation can be performed also by using train of pulses of 1 msec duration, which can be delivered by virtually all stimulators allowed for human use. Moreover, we developed a simple technique for visualising the time course of the changes in the direction of the postural response, based on the evaluation of the velocity vector of subject's centre of pressure. This method could be exploited in order to the test the efficacy of neck proprioceptive information in modifying the reference frame for processing vestibular signals in both physiological and pathological condition. PMID:24442983

  4. Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex

    PubMed Central

    Steinhauer, Stuart R.; Condray, Ruth; Pless, Misha L.

    2015-01-01

    Cognitive operations can be detected by reduction of the pupillary light response. Neurophysiological pathways mediating this reduction have not been distinguished. We utilized selective blockade of pupillary sphincter or dilator muscles to isolate parasympathetic or sympathetic activity during cognition, without modifying central processes. Pupil diameter was measured during the light reaction in 29 normal adults under three processing levels: No Task, during an easy task (Add 1), or a difficult task (Subtract 7). At three separate sessions, the pupil was treated with placebo, tropicamide (blocking the muscarinic sphincter receptor), or dapiprazole (blocking the adrenergic dilator receptor). With placebo, pupil diameter increased with increasing task difficulty. The light reaction was reduced only in the Subtract 7 condition. Dapiprazole (which decreased overall diameter) showed similar task-related changes in diameter and light reflex as for placebo. Following tropicamide (which increased overall diameter), there was a further increase in diameter only in the difficult task. Findings suggest two separate inhibitory components at the parasympathetic oculomotor center. Changes in baseline diameter are likely related to reticular activation. Inhibition of the light reaction in the difficult task is likely associated with cortical afferents. Sustained sympathetic activity also was present during the difficult task. PMID:26090217

  5. Vergence-dependent adaptation of the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    The gain of the vestibulo-ocular reflex (VOR) normally depends on the distance between the subject and the visual target, but it remains uncertain whether vergence angle can be linked to changes in VOR gain through a process of context-dependent adaptation. In this study, we examined this question with an adaptation paradigm that modified the normal relationship between vergence angle and retinal image motion. Subjects were rotated sinusoidally while they viewed an optokinetic (OKN) stimulus through either diverging or converging prisms. In three subjects the diverging prisms were worn while the OKN stimulus moved out of phase with the head, and the converging prisms were worn when the OKN stimulus moved in-phase with the head. The relationship between the vergence angle and OKN stimulus was reversed in the fourth subject. After 2 h of training, the VOR gain at the two vergence angles changed significantly in all of the subjects, evidenced by the two different VOR gains that could be immediately accessed by switching between the diverged and converged conditions. The results demonstrate that subjects can learn to use vergence angle as the contextual cue that retrieves adaptive changes in the angular VOR.

  6. Quantitative Assessment of the Canine Pupillary Light Reflex

    PubMed Central

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

    2013-01-01

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

  7. The defecation reflex in rats: fundamental properties and the reflex center.

    PubMed

    Nagano, Mayuko; Ishimizu, Yohko; Saitoh, Sanae; Okada, Hiromasa; Fukuda, Hiroyuki

    2004-03-31

    While pharmacological and physiological studies in rats are now increasing, physiological properties of their defecation have been scarcely investigated. This study was performed to define the properties of defecation in decerebrate rats, with special reference to the pontine defecation reflex center, which has been postulated in dogs. Intraluminal pressure was recorded from the colon and rectum with balloon-pressure transducer method using balloons of 15-20 mm in length and 0.1-0.3 ml in volume. Distention of a balloon in the descending colon and rectum with an additional injection of 0.03-0.1 ml air induced propulsive contractions on the descending colon and rectum. The mean of threshold pressures to induce propulsive contraction was 17.0 +/- 5.8 mm Hg (mean+/-S.E.) in the proximal part and 18.3 +/- 3.3 mm Hg in the distal part of the descending colon, and 11.8 +/- 1.3 mm Hg in the rectum. The maximum amplitude of propulsive contractions was 55 mm Hg in the rectum, 47 mm Hg in the distal part of the descending colon and 38 mm Hg in the proximal part. Similar colorectal propulsive contractions were produced by gastric distention (5-10 ml, 20-30 mm Hg) and electrical stimulation of the anal canal. Contrarily, spontaneous contractions of the proximal colon were suppressed by rectal distention and anal-canal stimulation. These results suggest that the descending colon and rectum, but not the proximal colon, were innervated by the pelvic afferent and efferent fibers mediating the defecation reflex. Pontine transection at the cerebellar peduncle level abolished colorectal propulsive contractions induced by distention of the stomach, descending colon and rectum, and stimulation of the anal canal, although much smaller contractions were still induced after the pontine transection. These results suggest that the pontine defecation reflex center exists and works in rats, as in dogs. PMID:15109938

  8. Crossed reflex reversal during human locomotion.

    PubMed

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

    2013-05-01

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

  9. Compensatory adrenal growth - A neurally mediated reflex

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

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

    PubMed

    Ives, Jonathan

    2014-07-01

    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

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

    NASA Astrophysics Data System (ADS)

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

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

  12. Habituation of an appetitive reflex in the honeybee.

    PubMed

    Braun, G; Bicker, G

    1992-03-01

    1. The proboscis extension reflex is an appetitive component of the bee's feeding behavior that is elicited by touching one antenna with a droplet of sugar water. Repetitive stimulation leads to a decrement and finally to the disappearance of the response, which can be restored by stimulating the contralateral antenna. This behavioral plasticity conforms to essential parametric characteristics for habituation. 2. The response was quantified by recording extracellularly from a muscle involved in proboscis movement, by measuring the duration of the proboscis extension, or by determining the number of trials necessary to abolish any visible response. 3. Because habituation was restricted to the repetitively stimulated antenna and did not generalize to the contralateral hemisphere, the neural circuits mediating habituation may be confined to one hemisphere. 4. State dependence of habituation could be demonstrated by showing that hungry animals exhibited a smaller response decrement and required more trials until disappearance of the response compared with satiated animals. The initial response and the subsequent response decrement are separate components determined by satiation level and stimulus strength. 5. Depleting the nervous system of monoamines by the use of reserpine abolished the reflex in 30% of the animals and reduced responsiveness in the remainder. Injection of octopamine or its metabolic precursor tyramine restored the reflex in reserpinized unresponsive animals, and tyramine also enhanced the muscle-spike discharge of reserpinized, responsive animals. In undepleted animals, tyramine application also accelerated the rate of habituation of the reflex. We therefore propose that octopaminergic neurons participate in mediating food arousal and the state dependence of habituation and, in a separate process, influence the response decrement during habituation. 6. Application of an acetylcholine esterase (AChE) inhibitor and a cholinergic receptor blocker confirmed histochemical data that implicate cholinergic transmission in the reflex pathways. 7. The combined pharmacological dissection of the reflex and immunocytochemical investigations of its chemical architecture provide evidence that the proboscis extension reflex is mediated by nonaminergic and monoaminergic pathways operating in parallel. PMID:1578245

  13. Driving a car using reflexive fuzzy behaviors

    SciTech Connect

    Pin, F.G.; Watanabe, Y.

    1992-01-01

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

  14. Driving a car using reflexive fuzzy behaviors

    SciTech Connect

    Pin, F.G.; Watanabe, Y.

    1992-10-01

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

  15. 3-Nitropropionic acid-induced depression of spinal reflexes does not involve 5-hydroxytryptaminergic system in contrast to ischemia-induced depression in neonatal rat spinal cord in vitro

    Microsoft Academic Search

    Rajesh Gupta; Archana Jha; Shripad B. Deshpande

    2008-01-01

    The involvement of 5-hydroxytryptaminergic (5-HTergic) system for the 3-nitropropionic acid (3-NPA)-induced depression of spinal reflexes was evaluated and compared with other energy deficiency condition (ischemia; glucose-free and O2-free). The monosynaptic (MSR) and polysynaptic reflex (PSR) potentials were recorded at ventral root by stimulating the corresponding dorsal root in neonatal rat spinal cord in vitro. Superfusion of 3-NPA (3.4mM) or ischemic

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

    PubMed

    Folgheraiter, Michele; Gini, Giuseppina

    2004-01-01

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

  17. Effect of vibration of the ankle stretch reflex in man.

    PubMed

    Agarwal, G C; Gottlieb, G L

    1980-07-01

    Vibration at frequencies above 50 Hz applied to the tendon of the extensor muscles of the ankle joint produce the tonic vibration reflex (TVR) which increases when the vibration frequency is increased. The TVR affects a joint's mechanical response to sinusoidal and random oscillations in a manner similar to that seen with tonic voluntary contraction. Although the myotatic reflex is suppressed by vibration, repeated stretches of sinusoidal oscillation produce an average EMG response which is not different in magnitude from the no vibration case. Either polysynaptic mechanisms at the spinal cord level of mechanisms involving higher centers (and possibly both) are able to overcome the inhibitory mechanisms at the Ia-alpha motoneuron level in producing a stretch evoked resonance near 6 Hz. The degree of inhibition of the myotatic component of the stretch reflex is proportional to the vibration frequency. This is in contrast to the facilitation of the myotatic reflex produced by tonic voluntary contraction. Vibration does not seem to influence the post-myotatic component (> 100 msec) of the stretch reflex. These results indicate that the post-myotatic responses to limb perturbation are not only different in their latency but also in their functional dependence upon peripheral influences. PMID:6159174

  18. Reflexive activation of newly instructed stimulus-response rules: evidence from lateralized readiness potentials in no-go trials.

    PubMed

    Meiran, Nachshon; Pereg, Maayan; Kessler, Yoav; Cole, Michael W; Braver, Todd S

    2015-06-01

    Previous behavioral and electrophysiological evidence has suggested that the instructions for a new choice task are processed even when they are not currently required, indicating intention-based reflexivity. Yet these demonstrations were found in experiments in which participants were set to execute a response (go). In the present experiment, we asked whether intention-based reflexivity would also be observed under unfavorable conditions in which participants were set not to respond (no-go). In each miniblock of our paradigm, participants received instructions for a task in which two new stimuli were mapped to right/left keys. Immediately after the instructions, a no-go phase began, which was immediately followed by a go phase. We found a significant stimulus-locked lateralized readiness potential in the first no-go trial, indicating reflexive operation of the new instructions. These results show that representing instructions in working memory provides sufficient conditions for stimuli to launch task processing, proceeding all the way until motor response-specific brain activation, which takes place even under unfavorable, no-go conditions. PMID:25216992

  19. Complete classification of reflexive polyhedra in four dimensions

    E-print Network

    Maximilian Kreuzer; Harald Skarke

    2000-02-28

    Four dimensional reflexive polyhedra encode the data for smooth Calabi-Yau threefolds that are hypersurfaces in toric varieties, and have important applications both in perturbative and in non-perturbative string theory. We describe how we obtained all 473,800,776 reflexive polyhedra that exist in four dimensions and the 30,108 distinct pairs of Hodge numbers of the resulting Calabi-Yau manifolds. As a by-product we show that all these spaces (and hence the corresponding string vacua) are connected via a chain of singular transitions.

  20. Reflex Modification by Acoustic Signals in Newborn Infants and in Adults.

    ERIC Educational Resources Information Center

    Hoffman, Howard S.; And Others

    1985-01-01

    Five experiments using identical reflex modification procedures on neonates and adults suggest developmental differences in processing auditory stimuli. Neonates failed to exhibit reflex inhibition by either prior acoustic or tactile stimuli. Adults exhibited robust reflex inhibition to these same stimuli. Developmental processes implied by these…

  1. Reflex control of sympathetic outflow and depressed baroreflex sensitivity following myocardial infarction

    Microsoft Academic Search

    Christine M. Jones; M. Susan Quinn; Anthony J. Minisi

    2008-01-01

    Reflex control of heart rate is frequently impaired following myocardial infarction. This is referred to as depressed baroreflex sensitivity. The aim of these experiments was to assess the function of other autonomic reflexes in dogs with depressed baroreflex sensitivity. Comparisons were made to dogs in whom baroreflex sensitivity was preserved or unchanged after myocardial infarction. Under chloralose–barbiturate anesthesia, reflex control

  2. Timing as a prominent factor of the Jendrassik manoeuvre on the H reflex

    Microsoft Academic Search

    T Kawamura; S Watanabe

    1975-01-01

    The influence of the Jendrassik manoeuvre on the myotatic reflex was analysed using a strain gauge as an indicator of the upper extremity movement and the H reflex of the soleus muscle as the test reflex. The most prominent factor responsible for the enhancement was not the speed or the strength of the manoeuvre but the timing from the instruction.

  3. The development of the pupillary light reflex and menace response in neonatal lambs and kids

    Microsoft Academic Search

    Afshin Raoofi; Pejman Mirfakhraie; Sorush Yourdkhani

    2011-01-01

    The aim of this study was to investigate the development of the pupillary light reflex and menace response in neonatal lambs and goat kids. Thirty lambs and 33 kids were assessed daily from birth until the pupillary light reflex and menace response had become established. All animals had a controlled pupillary light reflex within 20h of birth. Lambs and kids

  4. Adaptation to sensory-motor reflex perturbations is blind to the source of errors

    E-print Network

    Landy, Michael S.

    perturbations via a visual-motor reflex induced by slow drift of a large-field visual stimulus. This `visual a visually induced reflex in the reaching arm. Unlike adaptation to an external force, our method induces a perturbing reflex within the motor system itself, i.e., perturbing forces are self-generated. This novel

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Unpaced voluntary horizontal head oscillation was used to study the Vestibulo-Ocular Reflex (VOR) on Shuttle flights STS 7 and 8. Ten subjects performed head oscillations at 0.33 Hz + or - 30 deg amplitude under the followng conditions: VVOR (visual VOR), eyes open and fixed on a stationary target; VOR-EC, with eyes closed and fixed on the same target in imagination; and VOR-S (VOR suppression), with eyes open and fixed on a head-synchronized target. Effects of weightlessness, flight phase, and Space Motion Sickness (SMS) on head oscillation characteristics were examined. A significant increase in head oscillation frequency was noted inflight in subjects free from SMS. In subjects susceptible to SMS, frequency was reduced during their Symptomatic period. The data also suggest that the amplitude and peak velocity of head oscillation were reduced early inflight. No significant changes were noted in reflex gain or phase in any of the test conditions; however, there was a suggestion of an increase in VVOR and VOR-ES gain early inflight in asymptomatic subjects. A significant difference in VOR-S was found between SMS susceptible and non-susceptible subjects. There is no evidence that any changes in VOR characteristics contributed to SMS.

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

    PubMed

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

    2014-03-01

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

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

    PubMed

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

    2012-08-01

    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

  8. [Grasping reflex activity in utero is one element of fetal behavior (Grasping activity is a part of fetal ethology)].

    PubMed

    Jakobovits, Akos

    2007-09-01

    It is well known the newborns and infants activity include touching and grasping of various surrounding things lasting some months in postnatal period. The study involved observation of fetal grasping reflex during last trimester of pregnancy. The author was able to observe 6 episodes of grasping the umbilical cord in an other fetus grasping his scrotum, and another of his penis. When checked with Doppler sonography flow velocity waveforms of umbilical artery were disturbed temporarily. All fetuses were born some days or weeks later in good condition. Grasping reflex is an innocuous transitory episode from prenatal to postnatal life, without adverse sequelae. It is only one aspect of fetal behavior, and proof of its hereditary nature. PMID:17720675

  9. Process, Content, and Feminist Reflexivity: One Researcher's Exploration

    Microsoft Academic Search

    Tracey L. Hurd

    1998-01-01

    This article explores the unraveling of the relationship between research methodology, process, and content as revealed through my own feminist research project. I examine the evolution of my research process with one participant from a larger study, as I sought to better understand a story she told about racism. First, I address the theoretical underpinnings of feminist reflexivity and research,

  10. ORIGINAL PAPER Gill chemoreceptors and cardio-respiratory reflexes

    E-print Network

    Milsom, William

    ORIGINAL PAPER Gill chemoreceptors and cardio-respiratory reflexes in the neotropical teleost pacu chemoreceptors involved in cardio-respiratory responses to hypoxia in the neotropical teleost, the pacu arches, and were sensitive to O2 levels in the water and the blood. Ventilatory responses to all stimuli

  11. Evaluation of Reflex (fomesafen) herbicide for watermelon in Oklahoma

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effective preemergence herbicides are needed for weed control in watermelon grown from transplants. Reflex (fomesafen) was found to be effective and to exhibit crop safety in southeast USA. Trials were conducted during 2011 and 2012 in southeast Oklahoma to determine if this product would be useful...

  12. Reflexive responses to slipping in bipedal running robots

    Microsoft Academic Search

    Gary N. Boone; Jessica K. Hodgins

    1995-01-01

    Many robot applications require traversing uneven or unmodeled terrain. This paper explores strategies for one class of difficult terrain: slippery surfaces. We evaluate several reflexive responses to a slip using a dynamically simulated, three-dimensional, bipedal robot. We explore two kinds of reaction strategies. One strategy continues the step, in which the slip occurred. The other lifts the slipping foot and

  13. Reflex Control of Biped Robot Locomotion on A Slippery Surface

    Microsoft Academic Search

    Jong Hyeon Park; Ohung Kwon

    2001-01-01

    Biped robots are expected to walk on many different and previously unknown terrains, and thus they may walk on a slippery surface with low friction with no information on the surface a priori. Any fall-down due to unexpected slipping could cause costly damage to the robot and thus should be avoided. The paper proposes a reflex control method for biped

  14. Reflex inhibition of canine inspiratory intercostals by diaphragmatic tension receptors

    PubMed Central

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

    1999-01-01

    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. PMID:9831731

  15. Hindlimb venous distention evokes a pressor reflex in decerebrated rats

    PubMed Central

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

    2014-01-01

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

  16. Red reflex examination in neonates, infants, and children.

    PubMed

    2008-12-01

    Red reflex testing is an essential component of the neonatal, infant, and child physical examination. This statement, which is a revision of the previous policy statement published in 2002, describes the rationale for testing, the technique used to perform this examination, and the indications for referral to an ophthalmologist experienced in the examination of children. PMID:19047263

  17. Pattern of extraocular muscle activation during reflex blinking

    Microsoft Academic Search

    Craig Evinger; Karen A. Manning

    1993-01-01

    Studies in humans and rabbits suggest that cocontraction of extraocular muscles occurs with reflex and voluntary blinks. We determined the pattern of extraocular muscle activity elicited by blink-evoking visual and trigeminal stimuli by electromyographically recording antagonistic pairs of extraocular muscles in alert rabbits. In addition, we recorded the activity of antidromically identified oculomotor motoneurons in response to the same stimuli

  18. Multicyclic scratch reflex movements in the terrapin pseudemys scripta elegans

    Microsoft Academic Search

    J. G. M. Bakker; A. Crowe

    1982-01-01

    1.We present observations on the multicyclic scratch reflex in spinal terrapins as produced by a brief mechanical stimulus to specific regions of the shell. Hip and knee movements and EMG's from several muscles are simultaneously recorded.2.We confirm the results of Stein and Grossman (1980) that the EMG's during a movement cycle can be divided into three phases. We have related

  19. Contribution of stretch reflexes to locomotor control: a modeling study

    Microsoft Academic Search

    S. Yakovenko; V. Gritsenko; A. Prochazka

    2004-01-01

    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.

  20. H-Reflex of Single Motoneurones in Man

    Microsoft Academic Search

    J. V. Trontelj

    1968-01-01

    As early as 1918 Hoffmann described how electrical stimulation of the tibial nerve in man evokes, in addition to a direct motor response in the calf muscles, another well synchronized motor response at a latency of about 30 ms1. He concluded that this later response was identical with the myotatic reflex, because it had the following characteristics : (1) it

  1. Reflexes evoked by rhythmic stimulation of muscle nerves

    Microsoft Academic Search

    V. D. Glebovskii; N. T. Shutova

    1960-01-01

    Experiments were performed on cats in decerbrate rigidity. Stimulation of the central ends of some nerves to the quadriceps femoris muscle (100 stimuli per second) evoked a steady contraction or relaxation of the other heads of this muscle. Contractions corresponding to the myotatic reflex are observed with comparatively weak stimuli. Contractions appeared and increased in amplitude in response to stimulation

  2. Modulation of postural reflexes by voluntary movement1

    Microsoft Academic Search

    Gerald L. Gottlieb; Gyan C. Agarwal

    1973-01-01

    We have observed that there is a brief, 400 msec period of widespread facilitation of both the Hoffmann and the tendon-jerk reflexes associated with the initiation of a variety of local, voluntary, isometric efforts. It is suggested that the site of this facilitation lies within the spinal cord. We have also observed that this period is followed, for the Hoffmann

  3. Maturation of the human medial efferent reflex revisited

    PubMed Central

    Abdala, Carolina; Mishra, Srikanta; Garinis, Angela

    2013-01-01

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

  4. Muscle reflex in heart failure: the role of exercise training

    PubMed Central

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

    2012-01-01

    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. PMID:23060821

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

    ERIC Educational Resources Information Center

    Pardo, Elly

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

  6. Transference, Counter-Transference, and Reflexivity in Intercultural Education

    ERIC Educational Resources Information Center

    Shim, Jenna Min

    2015-01-01

    The article addresses the contributions psychoanalytic theory, particularly its concepts of "transference and counter-transference," can make to our understanding of reflexivity in intercultural education (IE). After the introduction, the article is organized into three parts. The first part is a psychoanalytic discussion that focuses on…

  7. Reconceptualising Learning as a Form of Relational Reflexivity

    ERIC Educational Resources Information Center

    Dyke, Martin

    2015-01-01

    The paper makes a connection between transmission modes and constructivism in sociology and education, respectively. There are parallels between Archer's criticism of upward and downward conflation in social theory, and approaches to learning in education. In her 2012 book, Archer seeks to reconceptualise socialisation as relational reflexivity.…

  8. Muscle reflex classification of low-back pain

    Microsoft Academic Search

    N. P. Reeves; J. Cholewicki; T. E. Milner

    2005-01-01

    It has been well documented that low-back pain (LBP) patients have longer muscle response latencies to perturbation than healthy controls. These muscle responses appear to be reflexive and not voluntary in nature, and as a result, might be useful for objectively classifying LBP. The goal of the study was to develop an objective and accurate method for classifying LBP using

  9. Nitric Oxide in the Dorsal Medulla Modulates Excitatory Somatosympathetic Reflexes

    Microsoft Academic Search

    Sheng-Xing Ma

    2007-01-01

    Activation of afferent cutaneous or mixed nerves, such as the sural or the sciatic, results in changes in sympa- thetic activity and arterial blood pressure by excitatory somatosympathetic reflexes (SSR). The underlying causes and modulation of SSR functions in the dorsal medulla are poorly understood. This review focuses our recent findings incor- porated with the publications from other investigators implicating

  10. Medical image. Reflex anoxic seizures in a toddler.

    PubMed

    de Almeida, Tilak; Pennock, Victoria; Skinner, Jonathan R

    2013-02-15

    We report a toddler with frequent pallid type breath-holding or reflex anoxic seizure episodes successfully treated with pacemaker implantation. A rhythm strip (from an ambulatory ECG monitor that shows an 18-second period of asystole) is shown. PMID:23463115

  11. Stiffness regulation by reflex action in the normal human hand.

    PubMed

    Carter, R R; Crago, P E; Keith, M W

    1990-07-01

    1. The torque and electromyographic (EMG) responses to stretch of the first dorsal interosseous muscle (externally imposed joint rotation) were recorded in five normal human subjects. The total measured stiffness was decomposed into three individual stiffness components; passive, intrinsic, and reflex. 2. The passive component was measured with the subject relaxed. Compared with the total response at the height of short latency reflex action, the passive component comprised 6-32% of the total stiffness recorded at an initial torque level of 20 N-cm [15-39% maximum voluntary contraction (MVC)]. The passive response also reflected a significant acceleration component during rapid joint rotation due primarily to digit inertia. 3. The intrinsic stiffness component, attributed to the mechanical properties of the active muscle fibers, was estimated by recording the response to joint rotation with the muscle activated in a distributed manner using a single intramuscular electrode. The dynamic stiffness (measured at the end of a ramp displacement) and the static stiffness (measured 1 s after onset of the displacement) both scaled in a straight-line manner with the initial torque level. This relationship held whether the initial torque level was varied by changes in recruitment or temporal summation. 4. The reflex component was calculated by subtracting the passive and the estimated intrinsic component from the total response. The timing of the EMG signal recorded during measurement of the total response and the fact that the estimated intrinsic component matched the total active response over the first 65-100 ms after displacement onset supported the case that this was the true reflex component. The peak of the reflex activity occurred 155-360 ms after displacement onset and, at this peak, accounted for 18-44% of the total stiffness (at an initial torque level of 20 N-cm). 5. Over the low to intermediate torque range employed, we observed that both intrinsic muscle stiffness and total stiffness increased with initial torque. Because total stiffness increased more rapidly than intrinsic stiffness, the difference between them (equal to reflex stiffness) also increased with initial torque. Furthermore, when the total active response trials (passive stiffness removed) were shifted vertically so that the initial torque levels matched, it was seen that reflex action did not reduce the stiffness range to less than the stiffness range encountered for the intrinsic response alone.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2388060

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

    PubMed

    Flaig, Christian

    2007-01-01

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

  13. Inhibition of spinal reflexes by paramedian reticular nucleus.

    PubMed

    Chai, C Y; Lin, Y F; Wang, H Y; Wu, W C; Yen, C T; Kuo, J S; Wayner, M J

    1990-10-01

    The inhibitory actions of the paramedian reticular nucleus (PRN), and its neighbouring structures, i.e., midline raphe nuclei (MRN) and dorsal medullary depressor area (DMD) on the knee jerk (KnJ) and crossed extension movement (CEM) induced by central sciatic stimulation and on the L5 ventral root response (EVRR) evoked by central tibial stimulation, were studied in cats under urethane (400 mg/kg) and alpha-chloralose (40 mg/kg) anesthesia alone, IP or further paralyzed with atracurium besylate (0.5 mg/kg/30 min), IV. Electrical stimulation of the above areas with rectangular pulses (80 Hz, 1.0 msec, 100-200 microA) decreased systemic arterial blood pressure (SAP) in an average value of: 36 +/- 3 mmHg for PRN; 19 +/- 2 mmHg for MRN; and 23 +/- 3 mmHg for DMD. The KnJ and CEM were almost completely suppressed by simultaneous PRN stimulation. The EVRR, including mono- and polysynaptic spinal reflexes with transmission velocity from 10 to 60 m/sec or above, were also suppressed. MRN stimulation only inhibited the KnJ, CEM and polysynaptic spinal reflexes with transmission velocities between 25 and 60 m/sec, but facilitated spinal reflexes with conduction velocities below 10 m/sec. On the other hand, DMD stimulation resulted in small suppression of KnJ, CEM and inhibition of polysynaptic spinal reflexes with conduction velocities between 25 and 60 m/sec. Even though MRN and DMD partially inhibited polysynaptic spinal reflexes, the magnitude of such inhibition was much smaller than that produced by PRN (-20% and -22% vs. -48%). The above-mentioned PRN effects on SAP and EVRR persisted in chronic animals decerebellated 9-12 days before.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2271962

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

    Microsoft Academic Search

    P J Delwaide; C Figiel; C Richelle

    1977-01-01

    The influence of passive changes in upper limb position on the excitability of three myotatic arc reflexes (soleus, quadriceps, and biceps femoris) of the lower limb has been explored on 42 volunteers. The results indicate that the excitability of the three myotatic arcs can be influenced at a distance by postural modifications of the upper limb. When the ipsilateral upper

  15. Post-activation depression of soleus stretch reflexes in healthy and spastic humans.

    PubMed

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

    2008-02-01

    Reduced depression of transmitter release from Ia afferents following previous activation (post-activation depression) has been suggested to be involved in the pathophysiology of spasticity. However, the effect of this mechanism on the myotatic reflex and its possible contribution to increased reflex excitability in spastic participants has not been tested. To investigate these effects, we examined post-activation depression in Soleus H-reflex responses and in mechanically evoked Soleus stretch reflex responses. Stretch reflex responses were evoked with consecutive dorsiflexion perturbations delivered at different intervals. The magnitude of the stretch reflex and ankle torque response was assessed as a function of the time between perturbations. Soleus stretch reflexes were evoked with constant velocity (175 degrees /s) and amplitude (6 degrees) plantar flexion perturbations. Soleus H-reflexes were evoked by electrical stimulation of the tibial nerve in the popliteal fossa. The stretch reflex and H-reflex responses of 30 spastic participants (with multiple sclerosis or spinal cord injury) were compared with those of 15 healthy participants. In the healthy participants, the magnitude of the soleus stretch reflex and H-reflex decreased as the interval between the stimulus/perturbation was decreased. Similarly, the stretch-evoked torque decreased. In the spastic participants, the post-activation depression of both reflexes and the stretch-evoked torque was significantly smaller than in healthy participants. These findings demonstrate that post-activation depression is an important factor in the evaluation of stretch reflex excitability and muscle stiffness in spasticity, and they strengthen the hypothesis that reduced post-activation depression plays a role in the pathophysiology of spasticity. PMID:17932663

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

    PubMed Central

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

    1998-01-01

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

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

    PubMed

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

    2009-07-01

    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

  18. Quantitative evaluation of the stretch reflex before and after hydro kinesy therapy in patients affected by spastic paresis.

    PubMed

    Pagliaro, P; Zamparo, P

    1999-04-01

    The aim of this study was the quantitative evaluation of the myotatic reflex in a group of 26 patients affected by stationary spastic paresis (6: hemiparesis; 5: paraparesis; 8: tetraparesis; 7: multiple sclerosis) before and after a treatment of hydro-kinesy therapy. The treatment was carried out in an indoor pool containing warm (32 degrees C) sea water and consisted of active and passive motion exercises, coordination exercises and immersion walking. The measured parameters were: (i) the peak input force (FpH) measured by means of an instrumented hammer with which the patellar tendon was hit; and (ii) the peak value of the corresponding reflex force of the quadriceps femoris (FpQ) measured by means of a load cell connected to the subject's ankle. The peak values of the reflex response (FpQ) were found to increase as a function of the intensity of the imposed stimulus and to reach a plateau between 15 and 30 N of FpH. A Student's t test applied to the paired values of FpQ (as measured at plateau conditions) on both the lower limbs, before and after therapy, showed no significant changes due to the treatment in the four groups of subjects. However, if all subjects were grouped regardless the type of illness: 1) the average reflex response of the affected limb (the one characterized before therapy by the higher FpQ values) was found to decrease following the treatment (75.1+/-26.7 N pre therapy and 69.1+/-29.3 N post therapy, p = 0.07, n = 26); and 2) the effect of the treatment was found to be significantly larger (p = 0.04, n = 26) on the affected limb (delta FpQ = 6.07+/-16.5 N) as respect with the contra lateral one (delta FpQ = -0.16+/-12.1 N). PMID:10098714

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

    PubMed Central

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

    2010-01-01

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

  20. Results of the REFLEX (Return Flux Experiment) Flight Mission

    NASA Technical Reports Server (NTRS)

    Pepin, R. O. (Compiler); Mauersberger, Konrad; Johnson, Bradford W.; Manning, Heidi K.

    1997-01-01

    The numerous problems occurring in this first flight of the REFLEX experiment, both in the spacecraft and with the instrument package, seriously constrained the acquisition and analysis of data and severely limited the interpretation of the data that were obtained. Of these, the ambient helium measurements appear to be the most promising. They are summarized and discussed in Appendix A. Further analyses could be attempted to establish the correct values for the energy centers as they varied during the mission. In addition, an extensive laboratory recalibration on a high-speed beam system could in principle provide corrections to be used in analyzing and interpreting the returned data set. The unknown malfunction which generated the energy drift needs to be understood and corrected before the REFLEX experiment is reflown; some hardware modification, or at least retuning, is likely to be required.

  1. Representation and Reflexivity in ICT for Development (Telecentre) Research

    Microsoft Academic Search

    Savita Bailur

    2009-01-01

    The author argues there is insufficient discussion of representation (the problems of showing the realities of the lived experiences\\u000a of the observed settings) and reflexivity (the relationship between knowledge and the ways whereby knowledge is produced)\\u000a in ICTD literature, particularly regarding telecentre users and non-users. It first reviews six papers from 2007-8 in Information Technologies and International Development and find

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  3. SMOS REFLEX 2003: L-band emissivity characterization of vineyards

    Microsoft Academic Search

    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

    2005-01-01

    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,

  4. Impulsive Consumption and Reflexive Thought: Nudging Ethical Consumer Behavior

    Microsoft Academic Search

    Leonhard K. Lades

    2012-01-01

    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

  5. Hypnotizability, hypnosis and prepulse inhibition of the startle reflex in healthy women: an ERP analysis.

    PubMed

    De Pascalis, Vilfredo; Russo, Emanuela

    2013-01-01

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

  6. Sweet taste and menthol increase cough reflex thresholds.

    PubMed

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

    2012-06-01

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

  7. The carotid sinus baroreceptor reflex in conscious rabbits.

    PubMed Central

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

    1980-01-01

    1. A method is described for altering the pressure across the wall of the carotid sinus in conscious rabbits by enclosing the carotid bifurcation in a rigid, fluid-filled capsule. The extracapsular arterial baroreceptors were denervated. 2. The baroreceptor--heart rate reflex, elicited by injecting vasoactive drugs or inflating aortic and vena caval cuffs, was used to test the new method. The function of the carotid sinus was shown to be unaffected by enclosure in the capsule. Denervation of the extracapsular baroreceptors reduced the gain of the baroreceptor--heart rate reflex two- to threefold. 3. The characteristics of the carotid baroreceptor reflex were studied in sixteen animals by the capsule method. Median estimates of maximum gain, and the range over which blood pressure changed, were 1.1 mmHg/mmHg and 57 mmHg respectively. There was good agreement between duplicate estimates made 1--20 days apart. 4. There was only a weak association between the effects on blood pressure and heart rate of altering carotid sinus transmural pressure. Autonomic blockade of the heart, so that its rate was fixed, did not reduce the gain or range of blood pressure change. PMID:7359409

  8. Prominent reflexive eye-movement orienting associated with deafness.

    PubMed

    Bottari, Davide; Valsecchi, Matteo; Pavani, Francesco

    2012-01-01

    Profound deafness affects orienting of visual attention. Until now, research focused exclusively on covert attentional orienting, neglecting whether overt oculomotor behavior may also change in deaf people. Here we used the pro- and anti-saccade task to examine the relative contribution of reflexive and voluntary eye-movement control in profoundly deaf and hearing individuals. We observed a behavioral facilitation in reflexive compared to voluntary eye movements, indexed by faster saccade latencies and smaller error rates in pro- than anti-saccade trials, which was substantially larger in deaf than hearing participants. This provides the first evidence of plastic changes related to deafness in overt oculomotor behavior, and constitutes an ecologically relevant parallel to the modulations attributed to deafness in covert attention orienting. Our findings also have implications for designers of real and virtual environments for deaf people and reveal that experiments on deaf visual abilities must not ignore the prominent reflexive eye-movement orienting in this sensory-deprived population. PMID:24168645

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

    PubMed

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

    1999-09-01

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

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

    Microsoft Academic Search

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

    2008-01-01

    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

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

    Microsoft Academic Search

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

    2011-01-01

    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

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

    Microsoft Academic Search

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

    2010-01-01

    Eyeblink and postauricular reflexes to standardized affective images were examined in individuals without (n = 37) and with (n = 20) autism spectrum disorders (ASDs). Affective reflex modulation in control participants replicated previous findings.\\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

  13. Reduced postactivation depression of soleus H reflex and root evoked potential after transcranial magnetic stimulation.

    PubMed

    Andrews, Jennifer C; Stein, Richard B; Roy, François D

    2015-07-01

    Postactivation depression of the Hoffmann (H) reflex is associated with a transient period of suppression following activation of the reflex pathway. In soleus, the depression lasts for 100-200 ms during voluntary contraction and up to 10 s at rest. A reflex root evoked potential (REP), elicited after a single pulse of transcutaneous stimulation to the thoracolumbar spine, has been shown to exhibit similar suppression. The present study systematically characterized the effect of transcranial magnetic stimulation (TMS) on postactivation depression using double-pulse H reflexes and REPs. A TMS pulse reduced the period of depression to 10-15 ms for both reflexes. TMS could even produce postactivation facilitation of the H reflex, as the second reflex response was increased to 243 ± 51% of control values at the 75-ms interval. The time course was qualitatively similar for the REP, yet the overall increase was less. While recovery of the H reflex was slower in the relaxed muscle, the profile exhibited a distinct bimodal shape characterized by an early peak at the 25-ms interval, reaching 72 ± 23% of control values, followed by a trough at 50 ms, and then a gradual recovery at intervals > 50 ms. The rapid recovery of two successively depressed H reflexes, ?25 ms apart, was also possible with double-pulse TMS. The effect of the TMS-induced corticospinal excitation on postactivation depression may be explained by a combination of pre- and postsynaptic mechanisms, although further investigation is required to distinguish between them. PMID:25995355

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2013-01-01

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

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

    PubMed

    LeMoyne, Robert; Mastroianni, Timothy

    2014-01-01

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

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

    PubMed Central

    Shemmell, Jonathan

    2015-01-01

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

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2015-01-21

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

  20. Rapid motor learning in the translational vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    Motor learning was induced in the translational vestibulo-ocular reflex (TVOR) when monkeys were repeatedly subjected to a brief (0.5 sec) head translation while they tried to maintain binocular fixation on a visual target for juice rewards. If the target was world-fixed, the initial eye speed of the TVOR gradually increased; if the target was head-fixed, the initial eye speed of the TVOR gradually decreased. The rate of learning acquisition was very rapid, with a time constant of approximately 100 trials, which was equivalent to <1 min of accumulated stimulation. These learned changes were consolidated over >or=1 d without any reinforcement, indicating induction of long-term synaptic plasticity. Although the learning generalized to targets with different viewing distances and to head translations with different accelerations, it was highly specific for the particular combination of head motion and evoked eye movement associated with the training. For example, it was specific to the modality of the stimulus (translation vs rotation) and the direction of the evoked eye movement in the training. Furthermore, when one eye was aligned with the heading direction so that it remained motionless during training, learning was not expressed in this eye, but only in the other nonaligned eye. These specificities show that the learning sites are neither in the sensory nor the motor limb of the reflex but in the sensory-motor transformation stage of the reflex. The dependence of the learning on both head motion and evoked eye movement suggests that Hebbian learning may be one of the underlying cellular mechanisms.

  1. Gigahertz signal processing using reflex optoelectronic switching matrices

    NASA Astrophysics Data System (ADS)

    Lam, D. K. W.; Syrett, B. A.

    1987-03-01

    The application of reflex optoelectronic switching matrices (ROSM) to signal processing in the gigahertz region is analyzed. Various signal processing functions such as delay generation, loop filtering, word generation/detection, integration, and digital to analog conversion are identified and their respective realizations in a ROSM are presented. It is found that for dedicated signal processing functions, simpler submatrices instead of full matrices can be employed with significant reduction in complexity and cost. The performance of ROSM's using currently commercially available components confirms the feasibility of gigahertz signal processing with ROSM's.

  2. A study of reflex optoelectronic switching matrices and their derivatives

    NASA Astrophysics Data System (ADS)

    Lam, D. K. W.

    1985-04-01

    The application of reflex optoelectronic switching matrices (ROSM) to signal processing in the GHz region is analyzed. Various signal processing functions such as delay generation, loop filtering, word generation/detection, integration and digital to analog conversions are identified and their respective realizations in a ROSM are presented. It is found that for dedicated signal processing functions, simpler submatrices instead of full matrices can be employed with significant reduction in complexity and cost. The performance of ROSMs using currently commercially available components confirms the feasibility of GHz signal processing with ROSMs.

  3. Identification of the vestibulo-ocular reflex dynamics.

    PubMed

    Ranjbaran, Mina; Galiana, Henrietta L

    2014-08-01

    The vestibulo-ocular reflex (VOR) plays an important role in our daily activities by enabling us to fixate on objects during head movements. Modeling and identification of the VOR improves our insight into the system behavior and helps in diagnosing various disorders. However, the switching nature of eye movements, including the VOR, makes the dynamic analysis challenging. In this work we are using integration of subspace and prediction error methods to analyze VOR dynamics. The performance of the method is evaluated using simulation studies and experimental data. PMID:25570250

  4. Hemodynamic changes associated with the diving reflex in the dog 

    E-print Network

    Jones, Charla Lynn

    1977-01-01

    HEMODYNAMIC CHANGES ASSOCIATED WIIH TH DIVING REFLEY IN THE DOG A Thesis CHARLA LYNN JONES Subm'tted to the Graduate Co'leg of Texas ASM I', . iv er si tv in partial fulfillment of the requitement for the degree of . STEH OF SCIENCE May 1977... Major Subj ect: Biology HEMODYNAMIC CHANGES ASSOCIATED WITH THE DIVING REFLEX IN THE DOG A Thesis by CHARLA LYNIN JONES Approved as to style and content by: / y . ) (Chairman of Committee) I (Head of D cpa tment) (Member) er ( embe May 1977...

  5. Calibration of ipsilateral stimulus transducer for acoustic reflex measurements.

    PubMed

    Olsen, S; Osterhammel, P A; Rasmussen, A N; Nielsen, L H

    1995-01-01

    Pure-tone Reference Equivalent Threshold Sound Pressure Level (RETSPL) of the ipsilateral stimulus receiver for acoustic reflex measurements on Madsen Electronics type Zodiac 901 impedance audiometer is provided. The results, obtained from 20 normal-hearing subjects, are achieved by comparing hearing threshold levels measured using a TDH 39 telephone (calibrated to ISO 389) with thresholds recorded using the ipsilateral stimulus insert phone. The calibration is referenced to an IEC-711 ear simulator and comprises the following frequencies: 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, 8000 Hz. PMID:8552975

  6. Abnormal pupillary light reflex with chromatic pupillometry in Gaucher disease.

    PubMed

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

    2014-02-01

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

  7. Super-high-speed reflex-type moving image camera

    NASA Astrophysics Data System (ADS)

    Drozhbin, Yu. A.; Trofimenko, Vladimir V.

    1991-04-01

    Experimental investigations ofthe spatial-time characteristics ofhigh-energy pulse lasers possessing generation pulse duration ranging from tens of microseconds up to tens of nanoseconds and spectral radiation band from vacuum ultra-violet up to infra-red (1O.6raLcr,m) are facifitated by use of optical-mechanical instruments of high-speed photography that employ reflex-type optical systems. High-speed ofthe mirror rotar rotation is obtained through utffization ofa turbine actuator on aerial supports.

  8. Bone scintigraphy in the reflex sympathetic dystrophy syndrome

    SciTech Connect

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

    1981-02-01

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

  9. PIV Application to Fluid Dynamicsof Bass Reflex Ports

    Microsoft Academic Search

    Massimiliano Rossi; Enrico Esposito; Enrico Tomasini

    \\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

  10. Abnormal Control of Orbicularis Oculi Reflex Excitability in Multiple Sclerosis

    PubMed Central

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

    2014-01-01

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

  11. Abnormal control of orbicularis oculi reflex excitability in multiple sclerosis.

    PubMed

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

    2014-01-01

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

  12. Central Cannabinoid Receptors Modulate Acquisition of Eyeblink Conditioning

    ERIC Educational Resources Information Center

    Steinmetz, Adam B.; Freeman, John H.

    2010-01-01

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

  13. Levodopa raises objective pain threshold in Parkinson's disease: a RIII reflex study

    PubMed Central

    Gerdelat?Mas, A; Simonetta?Moreau, M; Thalamas, C; Ory?Magne, F; Slaoui, T; Rascol, O; Brefel?Courbon, C

    2007-01-01

    Background Patients suffering from Parkinson's disease (PD) describe painful sensations that could be related to neuropathic pain. Experimental data have indicated the involvement of basal ganglia and dopaminergic pathways in central nociceptive processing. Aim The objective of this study was to assess and compare the effect of levodopa on the objective pain threshold in patients with PD and healthy subjects. Methods The objective pain threshold was assessed by the nociceptive flexion reflex (RIII) in 13 PD patients and 10 healthy subjects. Patients and healthy subjects were evaluated under two randomised conditions: with levodopa (ON) and without (OFF). Results Levodopa significantly increased the RIII threshold of PD patients (6.9 (1.2)?mA in the OFF condition vs 8 (1.1)?mA in the ON position; p?=?0.02). RIII threshold was significantly lower in PD patients than in healthy subjects in the OFF condition (6.9 (1.2)?mA vs 9.7 (3.4)?mA; p?=?0.02). RIII threshold did not change after levodopa administration in healthy subjects. Conclusion These results provide evidence of a dopaminergic modulation of objective pain threshold in PD patients. In addition, the decrease in RIII threshold in PD patients, in the OFF condition, compared with controls, confirms the existence of an objective pain perception disturbance in PD. PMID:17504881

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

    PubMed

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

    2015-06-01

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

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

    PubMed Central

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

    2014-01-01

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

  16. A review of myotatic reflexes and the development of motor control and gait in infants and children: a special communication.

    PubMed

    Myklebust, B M

    1990-03-01

    Although the mechanism of the phasic myotatic (or "stretch") reflex is well-known, the role of this reflex in adult gait remains speculative. The acquisition and development of locomotor skills with respect to the development of the myotatic reflex require further study in both healthy and neurologically impaired children. In this article, the well-documented properties of the healthy adult's myotatic reflex are compared with recent findings of the myotatic reflex in healthy infants and children and contrasted with reflex properties in patients with cerebral palsy. These data allow us to begin to characterize the emerging features of the stretch reflex in normal and pathological early development. From these data, we can begin to speculate about the relationship between changes in stretch reflexes and the acquisition of skillful movement and gait in early childhood. PMID:2304976

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

    PubMed

    Okada, H; Honda, M; Ono, H

    2001-05-01

    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

  18. Inhibitory effects of electrical stimulation of ventrolateral orbital cortex on the rat jaw-opening reflex

    Microsoft Academic Search

    Sun Zhang; Jing-Shi Tang; Bin Yuan; Hong Jia

    1998-01-01

    In previous studies, we have shown that electrically or chemically evoked activation of the ventrolateral orbital cortex (VLO) depresses the rat tail-flick (TF) reflex, and this antinociceptive effect is mediated by the periaqueductal gray (PAG). The aim of the present study was to examine whether electrical stimulation of the VLO could inhibit the rat jaw-opening reflex (JOR), and to determine

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

    PubMed

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

    1997-10-22

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

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

    ERIC Educational Resources Information Center

    Medova, Lucie

    2009-01-01

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

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

    Microsoft Academic Search

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

    2010-01-01

    The Hoffmann reflex is obtained through surface electromyographic recordings, and it is one of the most common neurophysiological techniques in exercise science. Measurement and evaluation of the peak-to-peak amplitude of the Hoffmann reflex has been guided by the observation that it is a variable response that requires multiple trials to obtain a stable mean. As a result, reliability assessment of

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

    ERIC Educational Resources Information Center

    Day, Jessica E.; Feeney, M. Patrick

    2008-01-01

    Purpose: The purpose of this study was to examine the effect of the 226-Hz probe level on the acoustic stapedius reflex threshold. Method: Contralateral reflex thresholds for a 1000-Hz pure-tone stimulus were obtained from 40 young adults with normal hearing using an experimental system at four 226-Hz probe levels (70, 75, 80, and 85 dB SPL) with…

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

    ERIC Educational Resources Information Center

    McPhillips, M.; Sheehy, N.

    2004-01-01

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

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

    ERIC Educational Resources Information Center

    Smyth, Mary; Anderson, Mike; Hammond, Geoff

    1999-01-01

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

  5. A Physiologically Based Clinical Measure for Spastic Reflexes in Spinal Cord Injury

    Microsoft Academic Search

    Ela N. Benz; T. George Hornby; Rita K. Bode; Robert A. Scheidt; Brian D. Schmit

    2005-01-01

    Benz EN, Hornby TG, Bode RK, Scheidt RA, Schmit BD. A physiologically based clinical measure for spastic reflexes in spinal cord injury. Arch Phys Med Rehabil 2005;86:52-9. Objective: To test the validity of the Spinal Cord Assess- ment Tool for Spastic reflexes (SCATS), a clinical tool in- tended to rate spastic motor behavior after spinal cord injury (SCI). Design: By

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

    E-print Network

    Sergio, Lauren E.

    1 1) The motor system - an overall view 2) Spinal reflexes and circuitry 3) Brainstem pathways Topic 6 ­ Organization of Motor System - Spinal and Brainstem Circuitry Sensory systems - Physical view 2) Spinal reflexes and circuitry 3) Brainstem pathways Topic 6 ­ Organization of Motor System

  7. A Development of Reflex HMD - HMD with time delay compensation capability

    Microsoft Academic Search

    Ryugo Kijima; Eijiroh Yamada; Takeo Ojika

    2001-01-01

    A Head Mounted Display system suffers largely from the time lag between human motion and the display output. The concept of Reflex HMD to compensate for the time lag is proposed and discussed. Based on this notion, a proto- type Reflex HMD is constructed. The rotation movement of the user's head is measured by a gyroscope, modulating the driving signal

  8. Processing Reflexives in a Second Language: The Timing of Structural and Discourse-Level Constraints

    ERIC Educational Resources Information Center

    Felser, Claudia; Cunnings, Ian

    2012-01-01

    We report the results from two eye-movement monitoring experiments examining the processing of reflexive pronouns by proficient German-speaking learners of second language (L2) English. Our results show that the nonnative speakers initially tried to link English argument reflexives to a discourse-prominent but structurally inaccessible antecedent,…

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

    ERIC Educational Resources Information Center

    Page, Miriam Dempsey

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

  10. Static and dynamic changes in body orientation modulate spinal reflex excitability in humans

    Microsoft Academic Search

    Maria Knikou; William Zev Rymer

    2003-01-01

    In the present study, we investigated the modulation pattern of the soleus H reflex in healthy subjects in response to imposed static and dynamic changes in body angle, referenced to the vertical plane. Soleus H reflexes were recorded using conventional methods with subjects either supine or while they were erect. Changes in body angle were initiated with subjects lying supine

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

    PubMed

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

    2013-05-01

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

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

    E-print Network

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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    The Hoffmann reflex is obtained through surface electromyographic recordings, and it is one of the most common neurophysiological techniques in exercise science. Measurement and evaluation of the peak-to-peak amplitude of the Hoffmann reflex has been guided by the observation that it is a variable response that requires multiple trials to obtain a…

  14. Impaired modulation of quadriceps tendon jerk reflex during spastic gait: differences between spinal and cerebral lesions

    Microsoft Academic Search

    Michael Faist; Matthias Ertel; Wiltrud Berger; Volker Dietz

    1999-01-01

    Summary In healthy subjects, functionally appropriate modulation of short latency leg muscle reflexes occurs during gait. This modulation has been ascribed, in part, to changes in presynaptic inhibition of Ia afferents. The changes in modulation of quadriceps tendon jerk reflexes during gait of healthy subjects were compared with those of hemi- or paraparetic spastic patients. The spasticity was due to

  15. A Study of Jaw Reflexes of the Awake Cat during Mastication and Locomotion

    Microsoft Academic Search

    J. P. Lund; T. Drew; S. Rossignol

    1984-01-01

    This paper reports on experiments on the jaw opening reflex carried out while awake unrestrained cats were eating or walking on a treadmill. It is shown that the jaw opening reflex response to low intensity stimulation diminished in all phases of the masticatory cycle. The response to higher threshold afferents, however, is phase modulated so that the largest responses occur

  16. Modelling of the activation of a stretch reflex in view of improving the muscular force

    Microsoft Academic Search

    L. Afilal; N. Manamanni; T. Cherouali; S. Moughamir; J. Zaytoon

    2001-01-01

    This paper presents a method to improve the muscular force for a patient's muscle during rehabilitation or training. The aim of this work is to formalise a stretch reflex called myotatic reflex by building an adequate model. This model is then used together with a muscle model to illustrate, through simulation, the efficiency and the feasibility of the method relatively

  17. Reflexive Polyhedra and their Applications in String and F-theory

    E-print Network

    Harald Skarke

    2000-02-29

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

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

    PubMed Central

    Chambers, B R; Gresty, M A

    1982-01-01

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

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

    ERIC Educational Resources Information Center

    Glass, Michael R.

    2014-01-01

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

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

    Microsoft Academic Search

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

    2005-01-01

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

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

    E-print Network

    Yabushita, Katsuhiko

    1995-01-01

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

  2. [Effect of immersion in water on the rudimentary reflexes of infants in the 1st months of life].

    PubMed

    Praznikov, V P

    1984-01-01

    Seizing and myotatic reflexes differ in their intensities in the right and left hands already from the first month of life in babies. It was shown that disappearing seizing and myotatic reflexes together with Moro's and Babinsky's reflexes in 3 1/2-4 months old babies can be elicited again during bathing. In the course of adaptation of babies to the water these reflexes disappear. PMID:6333121

  3. ESO Reflex: Using a Workflow Engine for Data Reduction

    NASA Astrophysics Data System (ADS)

    Ullgrén, M.; Maisala, S.; Oittinen, T.; Hook, R. N.; Romaniello, M.; Péron, M.; Licha, T.; Izzo, C.; Solin, O.; Savolainen, V.; Lindroos, J.; Järveläinen, P.

    2007-10-01

    Sampo {http://www.eso.org/sampo} (Hook et al. 2005) is a three year project that began in 2005 January. It is led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. The goal of the project is to assess the needs of the ESO community in the area of data reduction and analysis environments, and to create pilot software products that illustrate critical steps along the road to a new system. Those prototypes will not only be used to validate concepts and understand requirements, but will also be tools of immediate value for the community. The Sampo team has been researching new ways in which instrument pipeline recipes can be executed in a more flexible way. The requirements gathering process resulted in a prototype application called ESO Reflex {http://www.eso.org/sampo/reflex/} that offers a novel approach to astronomical data reduction. The integration of a modern graphical user interface and robust legacy data reduction algorithms gives the astronomer user the best of both worlds: ease of use combined with the re-use of well-tested algorithms.

  4. Trigemino-cervical reflex in spinal cord injury.

    PubMed

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

    2014-09-19

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

  5. Reflex effects on the heart of stimulating left atrial receptors

    PubMed Central

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

    1971-01-01

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

  6. Vestibulospinal control of reflex and voluntary head movement

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  7. Reflexive polyhedra, weights and toric Calabi-Yau fibrations

    E-print Network

    Maximilian Kreuzer; Harald Skarke

    2000-01-19

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

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

    PubMed Central

    2012-01-01

    Capsaicin, the pungent extract of red peppers, has been used in clinical research for almost three decades. Capsaicin has gained favor as the provocative agent of choice to measure cough reflex sensitivity, as it induces cough in a safe, reproducible, and dose-dependent manner. One of the major uses of capsaicin cough challenge testing has been to evaluate the effect of a pharmacological intervention on the human cough reflex. The current review summarizes the published experience with capsaicin inhalation challenge in the evaluation of drug effects on cough reflex sensitivity. A notable contrast evident between studies demonstrating a drug effect (inhibition of cough reflex sensitivity) and those that do not, is the predominance of healthy volunteers as subjects in the latter. This observation suggests that subjects with pathological cough, rather than normal volunteers, comprise the optimal group in which to evaluate the effect of potential antitussive agents on human cough reflex sensitivity. PMID:23146824

  9. NO donor SIN-1 potentiates monosynaptic reflexes in the cat spinal cord.

    PubMed

    Manjarrez, E; Rocha, T; Rojas-Piloni, G; Méndez, I; Vélez, D; Flores, A

    2001-08-28

    The effect produced by the nitric oxide donor SIN-1 on monosynaptic reflexes was examined. Experiments were performed on anesthetized, paralyzed and spinalized cats. Lumbar monosynaptic reflexes were produced by stimulation of Ia afferents. I.v. application of SIN-1 (500 microg/kg) produced a mean marked potentiation of 704% of pre-drug control (100%) in the amplitude of monosynaptic reflexes. In addition, in other experiments a concentration-dependent effect on the amplitude of monosynaptic reflexes was observed after microinjections of SIN-1 into the ventral horn (1 microl; 10(-12) - 10(-3) M), with a mean facilitatory effect of 355%. In both cases, the potentiation was reversible 45 min after i.v. or local application of SIN-1. These results provide the first evidence that monosynaptic reflexes can be potentiated by nitric oxide. PMID:11522945

  10. Reflexive anaphor resolution in spoken language comprehension: structural constraints and beyond

    PubMed Central

    Clackson, Kaili; Heyer, Vera

    2014-01-01

    We report results from an eye-tracking during listening study examining English-speaking adults’ online processing of reflexive pronouns, and specifically whether the search for an antecedent is restricted to syntactically appropriate positions. Participants listened to a short story where the recipient of an object was introduced with a reflexive, and were asked to identify the object recipient as quickly as possible. This allowed for the recording of participants’ o?ine interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our o?ine results show that the ultimate interpretation for reflexives was constrained by binding principles, the response time, and eye-movement data revealed that during processing participants were temporarily distracted by a structurally inappropriate competitor antecedent when this was prominent in the discourse. These results indicate that in addition to binding principles, online referential decisions are also affected by discourse-level information. PMID:25191290

  11. Myotatic reflex responses of non-disabled children and children with spastic cerebral palsy.

    PubMed

    Leonard, C T; Hirschfeld, H

    1995-09-01

    Surface electromyography (EMG) was used to examine lower-extremity myotatic reflex responses following patellar or Achilles tendon taps to normally developing, non-disabled infants and to individuals with cerebral palsy (CP). Reflex irradiation was present in non-disabled infants and infants with CP under two years of age. The only significant differences in myotatic reflex responses between the two groups at this age was the higher amplitude of the directly stimulated muscle of children with CP. After two years the amplitude did not differ between groups. Reflex irradiation, however, was greatly reduced in the non-disabled children but not in the children with cerebral palsy. These findings and those of non-human animal studies indicate the possible neural mechanisms that underlie reflex irradiation of individuals with CP. The potential clinical relevance of these findings is discussed. PMID:7589861

  12. An Intelligent Computerized Stretch Reflex Measurement System For Clinical And Investigative Neurology

    NASA Astrophysics Data System (ADS)

    Flanagan, P. M.; Chutkow, J. G.; Riggs, M. T.; Cristiano, V. D.

    1987-05-01

    We describe the design of a reliable, user-friendly preprototype system for quantifying the tendon stretch reflexes in humans and large mammals. A hand-held, instrumented reflex gun, the impactor of which contains a single force sensor, interfaces with a computer. The resulting test system can deliver sequences of reproducible stimuli at graded intensities and adjustable durations to a muscle's tendon ("tendon taps"), measure the impacting force of each tap, and record the subsequent reflex muscle contraction from the same tendon -- all automatically. The parameters of the reflex muscle contraction include latency; mechanical threshold; and peak time, peak magnitude, and settling time. The results of clinical tests presented in this paper illustrate the system's potential usefulness in detecting neurologic dysfunction affecting the tendon stretch reflexes, in documenting the course of neurologic illnesses and their response to therapy, and in clinical and laboratory neurologic research.

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

    PubMed Central

    2013-01-01

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

  14. The differential role of motor cortex in the stretch reflex modulation induced by changes in environmental mechanics and verbal instruction

    PubMed Central

    Shemmell, Jonathan; An, Je Hi; Perreault, Eric J.

    2009-01-01

    The motor cortex assumes an increasingly important role in higher mammals relative to that in lower mammals. This is true to such an extent that the human motor cortex is deeply involved in reflex regulation and it is common to speak of “transcortical reflex loops”. Such loops appear to add flexibility to the human stretch reflex, once considered to be immutable, allowing it to adapt across a range of functional tasks. However, the purpose of this adaptation remains unclear. A common proposal is that stretch reflexes contribute to the regulation of limb stability; increased reflex sensitivity during tasks performed in unstable environments supports this hypothesis. Alternatively, prior to movement onset, stretch reflexes can assist an imposed stretch, opposite to what would be expected from a stabilizing response. Here we show that stretch reflex modulation in tasks that require changes in limb stability is mediated by motor cortical pathways, and that these differ from pathways contributing to reflex modulation that depends on how the subject is instructed to react to an imposed perturbation. By timing muscle stretches such that the modulated portion of the reflex occurred within a cortical silent period induced by transcranial magnetic stimulation, we abolished the increase in reflex sensitivity observed when individuals stabilized arm posture within a compliant environment. Conversely, reflex modulation caused by altered task instruction was unaffected by cortical silence. These results demonstrate that task-dependent changes in reflex function can be mediated through multiple neural pathways and that these pathways have task specific roles. PMID:19846713

  15. Abnormalities of prepulse inhibition do not depend on blink reflex excitability: a study in Parkinson's disease and Huntington's disease

    Microsoft Academic Search

    J Valls-Solé; J. E Muñoz; F Valldeoriola

    2004-01-01

    ObjectivePrepulse inhibition of the blink reflex is a robust phenomenon with an interesting physiology and a large potential for clinical applicability. In the study presented here we investigated whether the blink reflex inhibition by a prepulse (BRIP) is influenced by the blink reflex excitability recovery (BRER).

  16. Tachykinin receptors mediate atropine-resistant rat duodenal reflex contractions in vivo.

    PubMed

    Giuliani, S; Tramontana, M; Lecci, A; Maggi, C A

    1996-01-01

    The study aimed to establish the possible role of tachykinins as mediators of atropine-resistant reflex contractions evoked by balloon distension in the proximal duodenum of urethane-anesthetized, guanethidine (34 mumol/kg s.c.)-pretreated rats. Distension of the balloon with a small amount (0.2-0.3 ml) of saline induced the appearance of phasic rhythmic contractions (about 11 mmHg in amplitude) which were promptly suppressed by either atropine (3 mumol/kg i.v.) or hexamethonium (28 mumol/kg i.v.). Despite the continuous i.v. infusion of atropine (2 mumol/h), low-amplitude rhythmic phasic contractions recovered, which were promptly suppressed by hexamethonium, to indicate the involvement of an atropine-resistant excitatory reflex. The amplitude of these atropine-resistant contractions was increased to about 4-5 mmHg by further distension of the balloon (0.4-0.6 ml) : under these conditions, the atropine-resistant contractions undergo a progressive fading. The fading was prevented by i.v. administration of the nitric oxide (NO) synthase inhibitor, L-nitroarginine methyl ester (L-NAME, 55 mumol/h), to provide a suitable baseline (amplitude of contractions was 7-8 mmHg) for studying the effect of tachykinin receptor antagonists. I.v. administration of the selective tachykinin NK2 receptor antagonists, MEN 10,627 (10-100 nmol/kg) and SR 48968 (100-300 nmol/kg) or of the selective NK1 antagonist SR 140333 (100 nmol/kg), at doses which do not affect the duodenal contractions induced by acetylcholine (5.5 mumol/kg i.v.), produced a prompt and long lasting suppression of the atropine-resistant reflex duodenal contractions produced by balloon distension in urethane-anesthetized rats, whilst SR-48965 (300 nmol/kg), the enantiomer of SR-48968 devoid, of NK2 receptor blocking activity, was without effect. I.v. administration of the selective NK1 receptor agonists [Sar9] substance P sulfone and septide or of the NK2 receptor selective agonist, [beta Ala8] neurokinin A(4-10) produced dose-dependent contractions of the duodenum. SR 140333 (100 nmol/kg i.v.) selectively antagonized the duodenal contractions produced by [Sar9] substance P sulfone and septide without affecting those produced by [beta Ala8] neurokinin A(4-10). On the other hand, MEN 10,627 (30-100 nmol/kg i.v.) and SR 48968 (100-300 nmol/kg i.v.) but not SR 48965 (300 nmol/kg i.v.) antagonized, at a comparable extent, duodenal contractions induced by both the selective NK2 and NK1 receptor agonists. We conclude that endogenous tachykinins are involved in mediating atropine-resistant reflex contractions evoked by distension of the rat duodenum in vivo: both NK1 and NK2 receptors are activated by endogenous ligands to produce NANC contractions of rat duodenum in vivo. However, the contractile response to i.v. administered NK1 receptor agonists, [Sar9] substance P sulfone and septide, may involve the release of mediators producing smooth muscle contraction via NK2 receptors. PMID:8878063

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  18. Soleus H-reflex tests and clinical signs of the upper motor neuron syndrome.

    PubMed Central

    Koelman, J H; Bour, L J; Hilgevoord, A A; van Bruggen, G J; Ongerboer de Visser, B W

    1993-01-01

    Soleus H-reflex tests are used for elucidating pathophysiological mechanisms in motor control. The cumulative vibratory inhibition of the soleus H-reflex, the ratio of the reflex to direct muscle potential (H to M ratio) and the recovery curve of the soleus H-reflex were studied in 38 patients with varying signs of the upper motor neuron syndrome for a possible relation with clinical features. The results were compared with those obtained from a group of healthy volunteers. The magnitude of vibratory inhibition decreased with increase of hypertonia. The H to M ratio increased as the activity of the tendon reflex was enhanced and correlated to a lesser degree with muscle tone. Both the H to M ratio and late facilitation of the soleus H-reflex recovery curve were elevated in clonus. The findings suggest that alterations in the results of soleus H-reflex tests relate to specific clinical features of the upper motor neuron syndrome. Possible pathophysiological implications are discussed. PMID:8331353

  19. A new predisposing factor for trigemino-cardiac reflex during subdural empyema drainage: a case report

    PubMed Central

    2010-01-01

    Introduction The trigemino-cardiac reflex is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. Clinically, trigemino-cardiac reflex has been reported to occur during neurosurgical skull-base surgery. Apart from the few clinical reports, the physiological function of this brainstem reflex has not yet been fully explored. Little is known regarding any predisposing factors related to the intraoperative occurrence of this reflex. Case presentation We report the case of a 70-year-old Caucasian man who demonstrated a clearly expressed form of trigemino-cardiac reflex with severe bradycardia requiring intervention that was recorded during surgical removal of a large subdural empyema. Conclusion To the best of our knowledge, this is the first report of an intracranial infection leading to perioperative trigemino-cardiac reflex. We therefore add a new predisposing factor for trigemino-cardiac reflex to the existing literature. Possible mechanisms are discussed in the light of the relevant literature. PMID:21118536

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

    PubMed

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

    2014-10-01

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

  1. A procedure concept for local reflex control of grasping

    NASA Technical Reports Server (NTRS)

    Fiorini, Paolo; Chang, Jeffrey

    1989-01-01

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

  2. Developmental tuning of reflexive attentional effect to biological motion cues.

    PubMed

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

    2014-01-01

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

  3. Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  4. Characterising our Universe with the REFLEX II cluster survey

    NASA Astrophysics Data System (ADS)

    Chon, G.; Boehringer, H.

    2014-07-01

    Galaxy clusters are important cosmological probes and they are in particular useful to constrain the parameters for the matter density and the density fluctuation amplitude in the Universe. The currently largest uncertainties in using galaxy clusters for cosmological tests originate in our imperfect knowledge of scaling relations between cluster observables and the masses of galaxy clusters. Using well defined statistical samples constructed from our REFLEX and NORAS survey of X-ray luminous clusters in the ROSAT All-Sky Survey, we aim for a comprehensive characterization of the statistical properties of the structure of galaxy clusters in the nearby Universe. We will discuss scaling relations, morphological distributions and the effect of the enviroment on these properties. For the first time we compare such results for flux- and volume-limted samples of galaxy clusters.

  5. 'Being there': multidimensionality, reflexivity and the study of emotional lives.

    PubMed

    Brownlie, Julie

    2011-09-01

    Emotional lives tend to be untidy. Yet despite a growing recognition of this, sociological research designs rarely mirror the multidimensionality they are striving to represent. This article takes as its starting point a recent study of beliefs and practices about emotional support and emotions talk in Britain, to illustrate how a methodologically mixed approach offers particular purchase on what passes between us in our everyday emotional lives and in research about these lives. The notion of 'being there' is drawn on to help make this argument. Moving between 'being there' as topic, a form of emotional support, and 'being there' as a methodological resource, the article concludes that the analytical claims we make about our emotional lives are strengthened through a methodologically mixed - and by necessity, reflexive - approach which explores, rather than smooths out, the ragged, sometimes indeterminate, edges between methods. PMID:21899523

  6. Spastic paresis: impaired spinal reflexes and intact motor programs.

    PubMed Central

    Berger, W; Horstmann, G A; Dietz, V

    1988-01-01

    Leg muscle EMG responses evoked by short treadmill acceleration impulses applied during stance were analysed in patients with spastic hemiparesis. The compensatory reactions on the unaffected side consisted of a diphasic pattern of leg muscle activation. The first response could best be described as a polysynaptic spinal stretch reflex response. This response was absent on the spastic side, except for its later, declining component. This remainder of the first response and the following activation of the antagonistic muscle was identical on both the unaffected and the spastic side. This part of the pattern is assumed to be centrally programmed (at the spinal level) and triggered by the termination of the acceleration impulse. PMID:3379431

  7. Specification of Extended Reflexive Ontologies in the context of CDSS.

    PubMed

    Sanchez, Eider; Toro, Carlos; Graña, Manuel; Sanín, Cesar; Szczerbicki, Edward

    2014-01-01

    Decision recommendations are a set of alternative options for clinical decisions (e.g. diagnosis, prognosis, treatment selection, follow-up and prevention) that are provided to decision makers by knowledge-based Clinical Decision Support Systems (k-CDSS) as aids. We propose to follow a reasoning over domain approach for the generation of decision recommendations, by gathering and inferring conclusions from production rules. In order to rationalize our approach we present a specification that will sustain the logic models supported in the Knowledge Bases we use for persistence. We introduce first the underlying knowledge model and then the necessary extensions that will convey towards the solution of the reported needs. The starting point of our approach is the work of Toro et al. [13] on Reflexive Ontologies (RO). We also propose an extension of RO, by including the handling and reasoning that production rules provide. Our approach speeds-up the recommendation generation process. PMID:25488229

  8. Critical reflexivity in financial markets: a Hawkes process analysis

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  9. Stick balancing with reflex delay in case of parametric forcing

    NASA Astrophysics Data System (ADS)

    Insperger, Tamas

    2011-04-01

    The effect of parametric forcing on a PD control of an inverted pendulum is analyzed in the presence of feedback delay. The stability of the time-periodic and time-delayed system is determined numerically using the first-order semi-discretization method in the 5-dimensional parameter space of the pendulum's length, the forcing frequency, the forcing amplitude, the proportional and the differential gains. It is shown that the critical length of the pendulum (that can just be balanced against the time-delay) can significantly be decreased by parametric forcing even if the maximum forcing acceleration is limited. The numerical analysis showed that the critical stick length about 30 cm corresponding to the unforced system with reflex delay 0.1 s can be decreased to 18 cm with keeping maximum acceleration below the gravitational acceleration.

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

    PubMed Central

    Verma, Rajesh; Gupta, Mani

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Truszkowski, Walt; Hinchey, Mike; Sterritt, Roy

    2005-01-01

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

  12. Repetitive exposure: Brain and reflex measures of emotion and attention

    PubMed Central

    Ferrari, Vera; Bradley, Margaret M.; Codispoti, Maurizio; Lang, Peter J.

    2010-01-01

    Effects of massed repetition on the modulation of the late positive potential elicited during affective picture viewing were investigated in two experiments. Despite a difference in the number of repetitions across studies (from 5 to 30), results were quite similar: the late positive potential continued to be enhanced when viewing emotional, compared to neutral, pictures. On the other hand, massed repetition did prompt a reduction in the late positive potential that was most pronounced for emotional pictures. Startle probe P3 amplitude generally increased with repetition, suggesting diminished attention allocation to repeated pictures. The blink reflex, however, continued to be modulated by hedonic valence, despite massive massed repetition. Taken together, the data suggest that the amplitude of the late positive potential during picture viewing reflects both motivational significance and attention allocation. PMID:20701711

  13. Pupillary light reflex to light inside the natural blind spot

    PubMed Central

    Miyamoto, Kentaro; Murakami, Ikuya

    2015-01-01

    When a light stimulus covers the human natural blind spot (BS), perceptual filling-in corrects for the missing information inside the BS. Here, we examined whether a filled-in surface of light perceived inside the BS affects the size of the short-latency pupillary light reflex (PLR), a pupil response mediated by a subcortical pathway for unconscious vision. The PLR was not induced by a red surface that was physically absent but perceptually filled-in inside the BS in the presence of a red ring surrounding it. However, a white large disk covering the BS unexpectedly induced a larger PLR than a white ring surrounding the BS border did, even though these two stimuli must be equivalent for the visual system, and trial-by-trial percepts did not predict PLR size. These results suggest that some physiological mechanism, presumably the retinal cells containing the photopigment melanopsin, receives the light projected inside the BS and enhances PLR. PMID:26115182

  14. Dynamic control of muscle stiffness and H reflex modulation during hopping and jumping in man.

    PubMed Central

    Dyhre-Poulsen, P; Simonsen, E B; Voigt, M

    1991-01-01

    1. The objective of the study was to evaluate the functional effects of reflexes on muscle mechanics during natural voluntary movements. The excitability of the H (Hoffmann) reflex was used as a measure of the excitability of the central component of the stretch reflex. 2. We recorded EMG, ground reaction forces and the H reflex in the soleus muscle in humans while landing from a downward jump, during drop jumping and during hopping. The movements were also recorded by high-speed cinematography. 3. The EMG pattern was adapted to the motor task. When landing the EMG in the soleus muscle and in the anterior tibial muscle showed preinnervation and alternating activity after touch down. When hopping there was little preinnervation in the soleus muscle, and the activity was initiated about 45 ms after touch down by a peak and continued unbroken until lift off. In the drop jumps the EMG pattern depended on the jumping style used by the subject. 4. The H reflex in the soleus muscle was strongly modulated in a manner appropriate to the requirements of the motor task. During landing from a downward jump the H reflex was low at touch down whereas while hopping it was high at touch down. During drop jumping it was variable and influenced by the jumping technique. 5. Muscle stiffness in the ankle joint was negative after touch down when landing, but always positive when hopping. 6. It is suggested that during landing the alternating EMG pattern after touch down was programmed and little influenced by reflexes. During hopping reflexes could contribute to the initial peak and the EMG during lift off. 7. The programmed EMG activity and the suppression of the H reflex while landing probably contribute to the development of the negative stiffness and change the muscles from a spring to a damping unit. PMID:1890636

  15. Endogenous angiotensin II and the reflex response to stimulation of cardiopulmonary serotonin 5HT3 receptors

    PubMed Central

    Veelken, R; Hilgers, K F; Scrogin, K E; Mann, J F E; Schmieder, R E

    1998-01-01

    Angiotensin (Ang) II modulates cardiovascular baroreflexes; whether or not the peptide influences chemosensitive cardiovascular reflexes is not known. We tested the hypothesis that Ang II modulates the reflex control of sympathetic nerve activity exerted by 5-hydroxytryptamine 3 (5HT3) cardiopulmonary receptors.The 5HT3 receptor agonist phenylbiguanide (PBG), infused intravenously for 15?min, elicited a sustained reflex decrease of renal sympathetic nerve activity (RSNA) but only transient (<3?min) changes of arterial blood pressure (BP) and heart rate (HR) in methohexital-anaesthesized rats.Infusion of Ang II at a dose that did not affect baseline BP, HR and RSNA enhanced the PBG-evoked reflex decrease of RSNA (?54±5% in Ang II treated versus ?33±6% in control rats after 15?min PBG, P<0.05, n=6 each) in methohexital-anaesthetized rats.The angiotensin converting enzyme (ACE) inhibitor lisinopril blunted the reflex responses to PBG in anaesthetized as well as conscious animals. The effect of the ACE inhibitor was abolished by concomitant infusion of Ang II.The reflex response to stimulation of cardiopulmonary 5HT3 afferents was also impaired by the Ang II type 1 receptor (AT1) blocker ZD7155 but not by the type 2 (AT2) blocker PD 123319.Infusion of a volume load to stimulate cardiopulmonary baroreceptors induced a gradual decrease of RSNA which was impaired by exogenous Ang II (RSNA ?26±6% in Ang II treated versus ?47±6% in control rats after volume load, P<0.05, n=6 each) but unaffected by ACE inhibition.The reflex control of RSNA by cardiopulmonary 5HT3 receptors is enhanced by Ang II via AT1 receptors. Thus, Ang II facilitates a chemosensitive cardiovascular reflex, in contrast to its inhibitory influences on mechanosensitive reflexes. PMID:9886768

  16. Projection neurons of the vestibulo-sympathetic reflex pathway.

    PubMed

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

    2014-06-15

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

  17. PROJECTION NEURONS OF THE VESTIBULO-SYMPATHETIC REFLEX PATHWAY

    PubMed Central

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

    2014-01-01

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

  18. Cholesteric Liquid Crystal Based Reflex Color Reflective Displays

    NASA Astrophysics Data System (ADS)

    Khan, Asad

    2012-02-01

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

  19. Excitability of lower limb myotatic reflex arcs under the influence of caloric labyrinthine stimulation. Analysis of the postural effects in man

    Microsoft Academic Search

    P J Delwaide

    1977-01-01

    The excitability changes of myotatic reflex arcs have been investigated in 36 volunteers by two methods (tendon reflex and tonic vibration reflex) in a bilateral invertigation of soleus, quadriceps, biceps femoris, and tibialis anterior after caloric stimulation of the labyrinth. The extensor myotatic reflexes are facilated during the irrigation and the nystagmus phases. Contrary to the soleus, quadriceps facilitation is

  20. Modulation of two types of jaw-opening reflex by stimulation of the red nucleus.

    PubMed

    Satoh, Yoshihide; Yajima, Eriko; Ishizuka, Ken'Ichi; Nagamine, Yasuhiro; Iwasaki, Shin-ichi

    2013-08-01

    The red nucleus (RN) is divided cytoarchitecturally into two parts, the parvicellular part (RPC) and the magnocellular part (RMC). The present study aims, first, to compare the effects of RN stimulation between low- and high-threshold afferents-evoked jaw opening reflexes (JORs), and secondly to compare the size of these effects in the RPC and RMC. Experiments were performed on rats anesthetized with urethane-chloralose. The JOR was evoked by electrical stimulation of the inferior alveolar nerve and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was either 1.2 (low-threshold) or 4.0 (high-threshold) times that necessary to elicit the JOR. Conditioning electrical stimulation of the RN significantly facilitated the JOR evoked by the low-threshold afferents. On the other hand, conditioning electrical stimulation of the RN significantly suppressed the JOR evoked by the high-threshold afferents. Microinjection of monosodium glutamate into the RN also facilitated the JOR evoked by the low-threshold afferents, but suppressed that evoked by high-threshold afferents. Facilitation did not differ between the RMC and the RPC. Suppression by the RMC stimulation was significantly greater than that by the RPC stimulation. These results suggest that the RN has distinct functional roles in the control of the JOR. PMID:23708019

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

    NASA Technical Reports Server (NTRS)

    Doba, N.; Reis, D. J.

    1974-01-01

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

  2. Role of Autonomic Reflex Arcs in Cardiovascular Responses to Air Pollution Exposure

    EPA Science Inventory

    The body responds to environmental stressors by triggering autonomic reflexes in the pulmonary receptors, baroreceptors, and chemoreceptors to maintain homeostasis. Numerous studies have shown that exposure to various gases and airborne particles can alter the functional outcome ...

  3. Red reflex examination in infants. Section on Ophthalmology. American Academy of Pediatrics.

    PubMed

    2002-05-01

    Red reflex examination is recommended for all infants. This statement describes the indications for and the technique to perform this examination, including indications for dilation of the pupils before examination and indications for referral to an ophthalmologist. PMID:11986467

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

    E-print Network

    Golden, Adam J

    2004-01-01

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

  5. A study of jaw reflexes of the awake cat during mastication and locomotion.

    PubMed

    Lund, J P; Drew, T; Rossignol, S

    1984-01-01

    This paper reports on experiments on the jaw opening reflex carried out while awake unrestrained cats were eating or walking on a treadmill. It is shown that the jaw opening reflex response to low intensity stimulation diminished in all phases of the masticatory cycle. The response to higher threshold afferents, however, is phase modulated so that the largest responses occur during the jaw closing phase. This is in accord with the need for increased protection of the soft tissues in this phase of the movement. In contrast, the digastric reflex amplitude does not change when the cat passes from quiet standing to walking on the treadmill. Evidence is presented that the electromyographic activity of the jaw closing muscles increases during upwards movement of the head during walking and decreases as the head falls. These data support the hypothesis that the myotatic reflex in the elevator muscles plays a role in stabilizing the mandible during locomotion. PMID:6242024

  6. Nonlinear modeling and identification of stretch reflex dynamics using support vector machines

    Microsoft Academic Search

    Mujahed Al Dhaifallah; David T. Westwick

    2009-01-01

    In this work, an algorithm that identifies Hammerstein models with support vector machine nonlinearities and output-error linear dynamics is proposed. This algorithm is used to identify a Hammerstein model of stretch reflex EMG dynamics from experimental data.

  7. Surface EMG crosstalk during phasic involuntary muscle activation in the nociceptive withdrawal reflex.

    PubMed

    Frahm, Ken S; Jensen, Michael B; Farina, Dario; Andersen, Ole K

    2012-08-01

    The human nociceptive withdrawal reflex is typically assessed using surface electromyography (sEMG). Based on sEMG, the reflex receptive field (RRF) can be mapped. However, EMG crosstalk can cause erroneous results in the RRF determination. Single differential (SD) vs. double differential (DD) surface EMG were evaluated. Different electrode areas and inter-electrode-distances (IED) were evaluated. The reflexes were elicited by electrical stimulation of the sole of the foot. EMG was obtained from both tibialis anterior (TA) and soleus (SOL) using both surface and intramuscular EMG (iEMG). The amount of crosstalk was significantly higher in SD recordings than in DD recordings (P < 0.05). Crosstalk increased when electrode measuring area increased (P < 0.05) and when IED increased (P < 0.05). Reflex detection sensitivity decreases with increasing measuring area and increasing IED. These results stress that for determination of RRF and similar tasks, DD recordings should be applied. PMID:22806372

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

    E-print Network

    Tangorra, James Louis, 1967-

    2003-01-01

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

  9. Inequality of the direct and consensual light reflexes in normal subjects

    Microsoft Academic Search

    S A Smith; C J Ellis; S E Smith

    1979-01-01

    Anisocoria in darkness and during reflex responses to unilateral light stimulation was studied in 150 normal subjects with television pupillometry. It was commonly found that the direct light reaction of the stimulation eye exceeded the consensual reaction of the other eye. This light-induced anisocoria, termed 'contraction anisocoria', had a mean value of 0.075 mm or 6.1 % of light reflex

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

    Microsoft Academic Search

    Jay M. GoldbergKathleen; Kathleen E. Cullen

    2011-01-01

    Here, we review the angular vestibulocollic reflex (VCR) focusing on its function during unexpected and voluntary head movements.\\u000a Theoretically, the VCR could (1) stabilize the head in space during body movements and\\/or (2) dampen head oscillations that\\u000a could occur as a result of the head’s underdamped mechanics. The reflex appears unaffected when the simplest, trisynaptic\\u000a VCR pathways are severed. The

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

    Microsoft Academic Search

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

    2003-01-01

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

  12. The effects of head position on skilled force production: implications for the tonic neck reflex

    E-print Network

    Guadagnoli, Mark Aloysious

    1990-01-01

    THE EFFECTS OF HEAD POSITION ON SKILLED FORCE PRODUCTION: IMPLICATIONS FOR THE TONIC NECK REFLEX A Thesis by MARK ALOYSIOUS GUADAGNOLI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE Nay 1990 Major Subject: Kinesiology THE EFFECT OF HEAD POSITION ON SKILLED FORCE PRODUCTION: IMPLICATIONS FOR THE TONIC NECK REFLEX A Thesis by MARK ALOYSIOUS GUADAGNOLI Approved as to style and content...

  13. Operation of a large-area reflex triode on a modular pulsed power generator

    Microsoft Academic Search

    D. P. Murphy; B. V. Weber; R. J. Commisso; R. J. Allen; D. G. Phipps; S. B. Swanekamp; D. Mosher; V. Harper-Slaboszewicz; K. A. Mikkelson; J. Goyer; J. Riordan

    2010-01-01

    Summary form only given. The SATURN pulsed-power machine is normally operated in negative polarity using up to 3 cathodes and 4 anodes to drive three electron-beam diodes in parallel. A large-area, reflex triode for <;1MV x-ray production is being tested on SATURN. The first shots with a reflex triode load used convolutes to connect the lines to a tri-axial feed

  14. Urethral sensory threshold and urethro-anal reflex latency in continent women

    Microsoft Academic Search

    Geraldo de Aguiar Cavalcanti; Homero Bruschini; Gilberto M. Manzano; Lydia P. Giuliano; João Antônio M. Nóbrega; Miguel Srougi

    2007-01-01

    Aims of study  The sensory evaluation of the lower urinary tract is summarized in the bladder proprioceptive sensitivity during cystometry.\\u000a Experimental studies suggest that abnormalities of the urethral innervation and micturition reflex can be related to the presence\\u000a of continence disturbances. This study aimed to measure the urethral sensory threshold and the urethro-anal reflex latency\\u000a in healthy volunteers, establishing reading criteria,

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

    Microsoft Academic Search

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

    2010-01-01

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

  16. Spinal manipulation results in immediate H-reflex changes in patients with unilateral disc herniation

    Microsoft Academic Search

    Y. Floman; N. Liram; A. N. Gilai

    1997-01-01

    The aim of this clinical investigation was to determine whether the abnormal H-reflex complex present in patients with S 1 nerve root compression due to lumbosacral disc herniation is improved by single-session lumbar manipulation. Twenty-four patients with unilateral disc herniation at the L5-S1 level underwent spinal H-reflex electro-physiological evaluation. This was carried out before and after single-session lumbar manipulation in

  17. Eccentric exercise inhibits the H reflex in the middle part of the trapezius muscle.

    PubMed

    Vangsgaard, Steffen; Nørgaard, Lars T; Flaskager, Brian K; Søgaard, Karen; Taylor, Janet L; Madeleine, Pascal

    2013-01-01

    The objectives of this study were to (1) investigate the modulation of the H reflex immediately after and 24 h after eccentric exercise in the presence of delayed-onset muscle soreness (DOMS) and (2) test the reproducibility of the H reflex in trapezius across days. H reflexes were recorded from the dominant middle trapezius muscle by electrical stimulation of the C3/4 cervical nerve in ten healthy subjects. DOMS was induced by eccentric exercise of the dominant shoulder. H reflexes were obtained in four sessions: "24 h before", "Pre", "Post", and "24 h after" eccentric exercise. Ratios of maximal H reflex and M wave responses (H (max)/M (max)) were compared between sessions. In addition, a between session comparison was done for the ratios of H reflex amplitudes (H (i_75)/M (max), and H (i_50)/M (max)) obtained from the stimulus intensity needed to obtain 75 and 50 % of H (max) at "24 h before". No ratio changes were found when comparing "24 h before" and "Pre" recordings. A decrease in H (i_50)/M (max) was found at "Post" (P < 0.05) and decreases in both H (i_75)/M (max) and H (i_50)/M (max) were observed at "24 h after" (P < 0.05). This study presented evidence that an acceptable day-to-day reproducibility of the H reflex could be obtained with the applied experimental setup. Furthermore, immediately after and 24 h after exercise a stronger stimulus intensity was needed to reach the same magnitude of the H reflex reflecting that the recruitment curve was shifted to the right. This modulation of the stimulus-response relationship could be caused by presynaptic inhibition of Ia afferent fibres' input to the motoneuron by group III and IV afferents. PMID:22573465

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

    Microsoft Academic Search

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

    1990-01-01

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

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

    PubMed Central

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Highstein, S. M.

    1998-01-01

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

  1. The cerebellum and sensorimotor coupling: Looking at the problem from the perspective of vestibular reflexes

    Microsoft Academic Search

    D. Manzoni

    2007-01-01

    Cerebellar modules process afferent information and deliver outputs relevant for both reflex and voluntary movements. The\\u000a response of cerebellar modules to a given input depends on the whole array of signals impinging on them. Studies on vestibular\\u000a reflexes indicate that the response of the cerebellar circuits to the vestibular input is modified by the integration of multiple\\u000a visual, vestibular and

  2. Thixotropic behaviour of human finger flexor muscles with accompanying changes in spindle and reflex responses to stretch.

    PubMed Central

    Hagbarth, K E; Hägglund, J V; Nordin, M; Wallin, E U

    1985-01-01

    Prompted by previous reports on muscle thixotropy, we have investigated changes in inherent and reflex stiffness of the finger flexor muscles of human subjects at rest, following transient conditioning manoeuvres involving contractions and/or length changes of the finger flexors. The stiffness measurements were combined with electromyographic recordings from forearm and hand muscles and with microneurographic recordings of afferent stretch responses in finger flexor nerve fascicles. Finger flexor stiffness was evaluated by measuring (a) the flexion angle of the metacarpo-phalangeal joints at which the system during rest balanced the force of gravity and (b) the speed and amplitude of angular finger extensions induced by recurrent extension torque pulses of constant strength delivered by a torque motor. In the latter case, extension drifts in the resting position of the fingers were prevented by a weak flexion bias torque holding the fingers in a pre-determined, semiflexed position against a stop-bar. Stiffness changes following passive large amplitude finger flexions and extensions were studied in subjects with nerve blocks or nerve lesions preventing neurally mediated contractions in the forearm and hand muscles. Inherent stiffness was enhanced following transient finger flexions and reduced following transient finger extensions. The after-effects gradually declined during observation periods of several minutes. Similar results were obtained in subjects with intact innervation who succeeded during the pre- and post-conditioning periods in keeping the arm and hand muscles relaxed (i.e. showed no electromyographic activity). In these subjects it was also found that the after-effects were similar for active and passive finger movements and that isometric voluntary finger flexor contractions loosened the system in a way similar to finger extensions. In some subjects electromyographic reflex discharges appeared in the finger flexors in response to the extension test pulses. When elicited by small ramp stretch stimuli of constant amplitude, the stretch reflex responses were found to vary in strength in parallel with the changes in inherent stiffness following the various conditioning manoeuvres. The strength of the multi-unit afferent stretch discharges in the muscle nerve, used as index of muscle spindle stretch sensitivity, varied in parallel with the changes in inherent stiffness. Post-manoeuvre changes in muscle spindle stretch sensitivity were seen also when the spindles were de-efferented by a nerve block proximal to the recording site. The results can be explained in terms of thixotropic behaviour of extra- and intrafusal muscle fibres.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2934547

  3. Perception and gut reflexes induced by stimulation of gastrointestinal thermoreceptors in humans.

    PubMed Central

    Villanova, N; Azpiroz, F; Malagelada, J R

    1997-01-01

    1. Experimental studies in animals suggest the existence of thermoreceptors in the gastrointestinal tract. Our aim was to investigate the distribution and specificity of upper gut thermoreceptors in humans. 2. In healthy subjects, thermal stimulation of the stomach (n = 8) and the small intestine (n = 6) was produced by means of a thermostat, which recirculates water at adjusted temperatures through an ultrathin intraluminal bag. Progressively warm (42, 47 and 52 degrees C) and cold (32, 22 and 12 degrees C) stimuli of 3 min duration were alternately applied at 13 min intervals. Perception was scored on a scale of 0-6 and gastric tone responses were measured with a barostat. 3. Thermal stimuli induced specific responses: cold stimuli induced abdominal cold sensation and a reflex contraction of the stomach, whereas warm stimuli induced warm sensation and a reflex gastric relaxation. 4. Thermal stimuli induced similar stimulus-related perception in the stomach and small intestine (temperatures between 12 and 49.5 +/- 0.5 degrees C were tolerated). 5. The reflex responses were site specific. Warm and cold stimulation of the stomach induced gastric reflexes (76 +/- 26 ml isobaric expansion at 47 degrees C, and 68 +/- 10 ml contraction at 12 degrees C; P < 0.05 for both). However, only warm, not cold, stimulation of the intestine induced enterogastric reflexes. 6. These results indicate that in humans, warm and cold receptors are distributed along the gastrointestinal tract and project afferent input both into perception and reflex circuits with specific topographic organization. PMID:9234208

  4. The olivocochlear reflex strength and cochlear sensitivity are independently modulated by auditory cortex microstimulation.

    PubMed

    Dragicevic, Constantino D; Aedo, Cristian; León, Alex; Bowen, Macarena; Jara, Natalia; Terreros, Gonzalo; Robles, Luis; Delano, Paul H

    2015-04-01

    In mammals, efferent projections to the cochlear receptor are constituted by olivocochlear (OC) fibers that originate in the superior olivary complex. Medial and lateral OC neurons make synapses with outer hair cells and with auditory nerve fibers, respectively. In addition to the OC system, there are also descending projections from the auditory cortex that are directed towards the thalamus, inferior colliculus, cochlear nucleus, and superior olivary complex. Olivocochlear function can be assessed by measuring a brainstem reflex mediated by auditory nerve fibers, cochlear nucleus neurons, and OC fibers. Although it is known that the OC reflex is activated by contralateral acoustic stimulation and produces a suppression of cochlear responses, the influence of cortical descending pathways in the OC reflex is largely unknown. Here, we used auditory cortex electrical microstimulation in chinchillas to study a possible cortical modulation of cochlear and auditory nerve responses to tones in the absence and presence of contralateral noise. We found that cortical microstimulation produces two different peripheral modulations: (i) changes in cochlear sensitivity evidenced by amplitude modulation of cochlear microphonics and auditory nerve compound action potentials and (ii) enhancement or suppression of the OC reflex strength as measured by auditory nerve responses, which depended on the intersubject variability of the OC reflex. Moreover, both corticofugal effects were not correlated, suggesting the presence of two functionally different efferent pathways. These results demonstrate that auditory cortex electrical microstimulation independently modulates the OC reflex strength and cochlear sensitivity. PMID:25663383

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

    PubMed

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

    2009-03-30

    A method for quantifying nociceptive withdrawal reflex receptive fields in human volunteers and patients is described. The reflex receptive field (RRF) for a specific muscle denotes the cutaneous area from which a muscle contraction can be evoked by a nociceptive stimulus. The method is based on random stimulations presented in a blinded sequence to 10 stimulation sites. The sensitivity map is derived by interpolating the reflex responses evoked from the 10 sites. A set of features describing the size and location of the RRF is presented based on statistical analysis of the sensitivity map within every subject. The features include RRF area, volume, peak location and center of gravity. The method was applied to 30 healthy volunteers. Electrical stimuli were applied to the sole of the foot evoking reflexes in the ankle flexor tibialis anterior. The RRF area covered a fraction of 0.57+/-0.06 (S.E.M.) of the foot and was located on the medial, distal part of the sole of the foot. An intramuscular injection into flexor digitorum brevis of capsaicin was performed in one spinal cord injured subject to attempt modulation of the reflex receptive field. The RRF area, RRF volume and location of the peak reflex response appear to be the most sensitive measures for detecting modulation of spinal nociceptive processing. This new method has important potential applications for exploring aspects of central plasticity in volunteers and patients. It may be utilized as a new diagnostic tool for central hypersensitivity and quantification of therapeutic interventions. PMID:19063920

  6. Physiological indices of visual fatigue due to VDT operation: pupillary reflexes and accommodative responses.

    PubMed

    Saito, S; Sotoyama, M; Saito, S; Taptagaporn, S

    1994-01-01

    In spite of the clarification of some significant physiological factors of visual fatigue caused by VDT work, pupillary reflexes have not been studied as to how they are affected after prolonged visual work. This study examined visual function changes objectively in terms of pupillary reflexes and lens accommodative responses after a 4-hr VDT operation task. The relationship between the two functions was also examined. Two measurements in this paper revealed the physiological function changes due to VDT operation. The subjects involved were five students with an average age of 22.6 years. First, near-reflex measurement ascertained decreases in amplitude and the velocity of accommodation function after the visual task. Second, light-reflex measurement revealed a delay of the reflex, an increase in the amplitude of the reflex, and a decrease in pupil size after the visual task. A weak correlation between the decrease in pupil size and accommodation function was found. The occurrence of visual fatigue due to 4-hr VDT operation was also confirmed by CFF measurements and reported subjective visual symptoms in this experiment. PMID:7806446

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

    PubMed Central

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

    2007-01-01

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

  8. Considering distortion product otoacoustic emission fine structure in measurements of the medial olivocochlear reflex

    PubMed Central

    Abdala, Carolina; Mishra, Srikanta K.; Williams, Tracy L.

    2009-01-01

    In humans, when the medial olivocochlear (MOC) pathway is activated by noise in the opposite ear, changes in distortion product otoacoustic emission (DPOAE) level, i.e., the MOC reflex, can be recorded in the test ear. Recent evidence suggests that DPOAE frequency influences the direction (suppression?enhancement) of the reflex. In this study, DPOAEs were recorded at fine frequency intervals from 500 to 2500 Hz, with and without contralateral acoustic stimulation (CAS) in a group of 15 adults. The MOC reflex was calculated only at DPOAE frequencies corresponding to peaks in the fine structure. Additionally, inverse fast-Fourier transform was conducted to evaluate MOC effects on individual DPOAE components. Results show the following: (1) When considering peaks only, the mean MOC reflex was ?2.05 dB and 97% of observations reflected suppression, (2) CAS reduced distortion characteristic frequency component levels more than overlap component levels, and (3) CAS produced an upward shift in fine structure peak frequency. Results indicate that when the MOC reflex is recorded at DPOAE frequencies corresponding to fine structure maxima (i.e., when DPOAE components are constructive and in phase), suppression is reliably observed and level enhancement, which probably reflects component mixing in the ear canal rather than strength of the MOC reflex, is eliminated. PMID:19275316

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

    PubMed

    Mikula, Ivan; Trkanjec, Zlatko; Negoveti?, Ruzica; Miskov, Snjezana; Demarin, Vida

    2005-06-01

    We investigated the brainstem blink reflex in patients suffering from idiopathic and symptomatic trigeminal neuralgia to establish possible dysfunction in the reflex cycle and determine eventual differences between the two disease types. The study included 35 patients with idiopathic disease and seven patients with symptomatic disease, their results compared with those of 50 normal controls. We stimulated the forehead afferents of the supraorbital nerve and recorded the response from both orbicularis oculi muscles. We tested latencies of bilateral late components (R2, R2'), irritative R3 component and the incidence of R3 component. The patients with idiopathic trigeminal neuralgia showed normal parameters of blink reflex, except for the greater incidence of R3 component. Patients with symptomatic trigeminal neuralgia showed prolonged latencies of R2, R2' and R3 components when stimulating the afflicted side, but no significant difference in incidence of R3 component compared with the control group. The results indicate that abnormalities of blink reflex are significantly different in the two groups of patients. The high incidence of R3 component seems to be typical of idiopathic disease, whereas the prolonged latencies of late reflex components after stimulation of the afflicted side seem to be typical for symptomatic disease. These results suggest that testing the blink reflex may prove a significant aid in distinguishing the idiopathic and symptomatic disease types. PMID:16053198

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  11. Evolution inclusions governed by the difference of two subdifferentials in reflexive Banach spaces

    NASA Astrophysics Data System (ADS)

    Akagi, Goro; Ôtani, Mitsuharu

    The existence of strong solutions of Cauchy problem for the following evolution equation du(t)/dt+??1(u(t))-??2(u(t))?f(t) is considered in a real reflexive Banach space V, where ??1 and ??2 are subdifferential operators from V into its dual V*. The study for this type of problems has been done by several authors in the Hilbert space setting. The scope of our study is extended to the V- V* setting. The main tool employed here is a certain approximation argument in a Hilbert space and for this purpose we need to assume that there exists a Hilbert space H such that V?H?H*?V* with densely defined continuous injections. The applicability of our abstract framework will be exemplified in discussing the existence of solutions for the nonlinear heat equation: ut(x,t)-?pu(x,t)-|u|u(x,t)=f(x,t), x??, t>0, u|=0, where ? is a bounded domain in RN. In particular, the existence of local (in time) weak solution is shown under the subcritical growth condition q

  12. Effects of interstitial cystitis on the acoustic startle reflex in cats

    PubMed Central

    Hague, Devon W.; Stella, Judi L.; Tony Buffington, C. A.

    2015-01-01

    Objective To compare acoustic startle reflexes (ASRs) of healthy cats and cats with interstitial cystitis (IC). Animals 28 healthy cats (11 males and 17 females) and 20 cats with IC (13 males and 7 females). Procedures To evaluate the effect of neutering on ASRs, ASRs in neutered and unneutered healthy cats were measured. To evaluate the effect of housing facility acclimation on ASRs in cats with IC, ASRs were measured in cats with IC within 1 month after arrival at the housing facility and again 2 to 3 months after arrival. To evaluate the effect of the environment on ASRs, ASRs were evaluated in all cats with and without IC after acclimation but before and then after environmental enrichment. Results Neutering led to a significant decrease in overall ASR in the healthy cats. Habituation to the housing facility resulted in a significant decrease in overall ASR of female but not male cats with IC. Environmental enrichment led to a significant decrease in ASR in cats with IC but not in healthy cats. Conclusions and Clinical Relevance The magnitude of the ASR appeared to be sensitive to environmental conditions and affected by sex, both in healthy cats and cats with IC. It was also higher in cats with IC versus healthy cats, except when cats were housed in a highly enriched environment. Impact for Human Medicine Treatment approaches that include reduction of a patient’s perception of environmental unpredictability may benefit humans with IC. PMID:23270359

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

    PubMed Central

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

    2014-01-01

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

  14. Muscle stretch used as conditioning stimulus for assessing a reciprocal inhibition.

    PubMed

    Pérot, C; Mora, I; Goubel, F

    1992-01-01

    The disynaptic Ia-alpha inhibition between the tibialis anterior and the soleus muscles is now well known. This neuronal organization has been established thanks to the analysis of the Hoffmann reflex (H reflex) changes following an electrical stimulation of the antagonist muscle nerve. In some cases, anatomical constraints impede the use of this classical technique for assessing a reciprocal Ia inhibition between muscles. Furthermore, an electrical stimulus solicits the primary spindle afferents in conditions which are very different from their natural stimulus: the muscle stretch. Thus we have undertaken to analyse the changes of a soleus H reflex following a rapid stretch of the ankle dorsiflexors and therefore of their prime-mover: the tibialis anterior. The mechanical perturbations were imposed with a strong initial acceleration and a limited angular displacement thanks to an original device including electromagnet and spring. This technique, derivated from the quick release technique, was applied on relaxed muscles to avoid a co-contraction phenomenon. 45 to 50 ms after the initiation of the mechanical perturbation an early reflex response was observed on the stretched tibialis anterior. The area of this first reflex response was related to the initial acceleration of the passive dorsiflexion. Several arguments are presented in favour of the myotatic origin of this reflex component. The passive dorsiflexion used as a conditioning stimulus led to a strong and longlasting inhibition of the test soleus H reflex. The early inhibition of the soleus H reflex was observed only about 18 ms after the conditioning stimulus.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1526213

  15. Anatomic patterning in the expression of vestibulosympathetic reflexes

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; Yates, B. J.; McAllen, R. M.

    2000-01-01

    To investigate the possibility that expression of vestibulosympathetic reflexes (VSR) is related to a nerve's anatomic location rather than its target organ, we compared VSR recorded from the same type of postganglionic fiber [muscle vasoconstrictor (MVC)] located at three different rostrocaudal levels: hindlimb, forelimb, and face. Experiments were performed on chloralose-anesthetized cats, and vestibular afferents were stimulated electrically. Single MVC unit activity was extracted by spike shape analysis of few-fiber recordings, and unit discrimination was confirmed by autocorrelation. Poststimulus time histogram analysis revealed that about half of the neurons were initially inhibited by vestibular stimulation (type 1 response), whereas the other MVC fibers were initially strongly excited (type 2 response). MVC units with types 1 and 2 responses were present in the same nerve fascicle. Barosensitivity was equivalent in the two groups, but fibers showing type 1 responses fired significantly faster than those giving type 2 responses (0.29 +/- 0.04 vs. 0.20 +/- 0.02 Hz). Nerve fibers with type 1 responses were most common in the hindlimb (21 of 29 units) and least common in the face (2 of 11 units), the difference in relative proportion being significant (P < 0.05, chi(2) test). These results support the hypothesis that VSR are anatomically patterned.

  16. The human vestibulo-ocular reflex during linear locomotion

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  17. Primate translational vestibuloocular reflexes. IV. Changes after unilateral labyrinthectomy

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  18. [The cardiovascular reflex tests in autonomic cardiac neuropathy diagnosis].

    PubMed

    Strobescu, Elena; Graur, Mariana

    2002-01-01

    Ewing's five standard cardiovascular reflex tests were used for the assessment of autonomic function. Changes in heart rate during deep inspiration and expiration, Valsalva manoeuvre or standing up evaluate parasympathetic innervation, whereas blood pressure fluctuations during standing up and handgrip evaluate sympathetic innervation. According to physiological principles we must remind that each test is useful predominantly but not exclusively to reveal the impairment of parasympathetic or sympathetic innervation. A total of 271 patients (247 with diabetes mellitus) were estimated for the diagnosis of autonomic neuropathy. Computed time domain analysis of the heart rate variability reveals 21% of the patients with autonomic neuropathy, but this method doesn't rich the performance of spectral analysis witch is x3 times greater. The deep inspiration and expiration remains the preferable test according to its sensibility, specificity and predictive value. I found that handgrip test has, beside the known limitations (arterial hypertension, heart failure, valvular disease, emphysema, advanced diabetic retinopathy, drugs like digitalis, beta-receptor blockers, antihypertensives, sedatives, etc.) one more linked by the hand muscular force. Orthostatic hypertension has too many false results so the interpretation must be done with much precaution. PMID:14974222

  19. Vestibulo-ocular reflex modification after virtual environment exposure.

    PubMed

    Di Girolamo, S; Picciotti, P; Sergi, B; Di Nardo, W; Paludetti, G; Ottaviani, F

    2001-01-01

    Immersion in an illusory world is possible by means of virtual reality (VR), where environmental perception is modified by artificial sensorial stimulation. The application of VR for the assessment and rehabilitation of pathologies affecting the vestibular system, in terms of both diagnosis and care, could represent an interesting new line of research. Our perception of reality is in fact based on static and dynamic spatial information perceived by our senses. During head movements in a virtual environment the images on the display and the labyrinthine information relative to the head angular accelerations differ and therefore a visuo-vestibular conflict is present. It is known that mismatches between visual and labyrinthine information may modify the vestibulo-oculomotor reflex (VOR) gain. We studied the post-immersion modifications in 20 healthy subjects (mean age 25 years) exposed to a virtual environment for 20 min by wearing a head-mounted display. VOR gain and phase were measured by means of harmonic sinusoidal stimulation in the dark before, at the end of and 30 min after VR exposure. A VOR gain reduction was observed in all subjects at the end of VR exposure which disappeared after 30 min. Our data show that exposure to a virtual environment can induce a temporary modification of the VOR gain. This finding can be employed to enable an artificial, instrumental modification of the VOR gain and therefore opens up new perspectives in the assessment and rehabilitation of vestibular diseases. PMID:11349781

  20. Laryngeal afferent activity and reflexes in the guinea pig.

    PubMed

    Tsubone, H; Sant'Ambrogio, G; Anderson, J W; Orani, G P

    1991-11-01

    We have investigated the various sensory modalities represented in the laryngeal nerves of the guinea pig. In addition, we have examined the defensive responses to mechanical stimuli and capsaicin instillation into the laryngeal lumen of the same species. Recording from both the whole superior laryngeal nerve and from single units of the same nerve revealed the presence of afferent activity related (1) to the contraction of laryngeal muscles and/or the 'tracheal tug', (2) to transmural pressure changes, either positive or negative and (3) to mechanical and chemical irritants. The irritant type receptors of this species, when challenged with water solutions, show two distinct patterns of activation: some behave as osmoreceptors, some respond to the lack of chloride ions. Challenges with capsaicin solutions activated one ending with the characteristics of a C-fiber receptor that failed to respond to a subsequent trial. This behavior is consistent with the reflex apnea, dependent on an intact laryngeal innervation, induced by capsaicin instillation that was not elicitable on repeating the challenge. Cough to mechanical probing of the supraglottic area depended on an intact SLN, whereas cough elicited from the subglottic area depended on an intact RLN. Cough to mechanical stimulation could not be desensitized by capsaicin. These findings suggest the presence of two independent afferent pathways for defensive responses. PMID:1780601

  1. Distribution of Ia effects onto human hand muscle motoneurones as revealed using an H reflex technique.

    PubMed Central

    Mazzocchio, R; Rothwell, J C; Rossi, A

    1995-01-01

    1. The possibility of eliciting H reflexes in relaxed hand muscles using a collision between the orthodromic impulses generated by magnetic cortical stimulation and the antidromic motor volley due to a supramaximal (SM) peripheral nerve stimulus was investigated in seven subjects. 2. Magnetic stimuli, applied through a circular coil (outer diameter, 13 cm) centred at the vertex, evoking EMG responses of 3-5 mV amplitude in the relaxed abductor digit minimi (ADM) muscle, and SM test stimuli to the ulnar nerve at the wrist producing a direct maximal motor response (Mmax) in the ADM muscle, were given either alone or combined. 3. In all subjects, combined cortical and SM ulnar stimulation produced a response after the Mmax with the latency of an H reflex evoked by the ulnar stimulus. This response occurred only within interstimulus intervals (1-20 ms) compatible with collision in the motor axons. The response behaved like an H reflex being time-locked to the SM ulnar stimulus, facilitated by voluntary activation of ADM muscle, depressed by vibration (4 s, 100 Hz) of ADM tendon and by a submotor-threshold ulnar nerve stimulus applied 50 and 80 ms before the combined stimulation, respectively. 4. In some subjects, it was also possible to distinguish an earlier response preceding the H reflex by 3 ms. Evidence is given that this response is probably of cortical origin. 5. Varying the intensity of magnetic stimulation resulted in a non-linear relationship between the H reflex size and the size of the cortical response. When the latter was between 5-25% of Mmax, H reflexes were small (2.5-7.5% of Mmax); with cortical responses between 25-50% of Mmax, there was a steep increase in H reflex amplitude (10-30% of Mmax). We suggest that this behaviour is due to an uneven distribution of Ia effects within the motoneurone pool. PMID:8583410

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

    PubMed

    Riskin, Arieh; Bamberger, Peter

    2014-01-01

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

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

    SciTech Connect

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

    2011-08-01

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

  4. Frequency response of human vestibular reflexes characterized by stochastic stimuli.

    PubMed

    Dakin, Christopher J; Son, Gregory M Lee; Inglis, J Timothy; Blouin, Jean-Sébastien

    2007-09-15

    Stochastic vestibular stimulation (SVS) can be used to study the postural responses to unpredictable vestibular perturbations. The present study seeks to determine if stochastic vestibular stimulation elicits lower limb muscular responses and to estimate the frequency characteristics of these vestibulo-motor responses in humans. Fourteen healthy subjects were exposed to unpredictable galvanic currents applied on their mastoid processes while quietly standing (+/-3 mA, 0-50 Hz). The current amplitude and stimulation configuration as well as the subject's head position relative to their feet were manipulated in order to determine that: (1) the muscle responses evoked by stochastic currents are dependent on the amplitude of the current, (2) the muscle responses evoked by stochastic currents are specific to the percutaneous stimulation of vestibular afferents and (3) the lower limb muscle responses exhibit polarity changes with different head positions as previously described for square-wave galvanic vestibular stimulation (GVS) pulses. Our results revealed significant coherence (between 0 and 20 Hz) and cumulant density functions (peak responses at 65 and 103 ms) between SVS and the lower limbs' postural muscle activity. The polarity of the cumulant density functions corresponded to that of the reflexes elicited by square-wave GVS pulses. The SVS-muscle activity coherence and time cumulant functions were modulated by current amplitude, electrode position and head orientation with respect to the subject's feet. These findings strongly support the vestibular origin of the lower limb muscles evoked by SVS. In addition, specific frequency bandwidths in the stochastic vestibular signal contributed to the early (12-20 Hz) and late components (2-10 Hz) of the SVS-evoked muscular responses. These frequency-dependent SVS-evoked muscle responses support the view that the biphasic muscle response is conveyed by two distinct physiological processes. PMID:17640935

  5. Trigeminocardiac reflex in neurosurgical practice: An observational prospective study

    PubMed Central

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

    2013-01-01

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

  6. Stretch reflex responses in the human elbow joint during a voluntary movement.

    PubMed Central

    Bennett, D J

    1994-01-01

    1. The responsiveness of the stretch reflex is modulated during human voluntary limb movements. The influence of this modulation on the limb mechanical properties (stiffness) was investigated. 2. Subjects were taught to replicate accurately a rapid (4.0 rad s-1) targeted elbow flexion movement of 1 rad. From the onset of 12% of the trials a sinusoidal position disturbance (0.05 rad) was superimposed on the normal (trained) movement trajectory. The net joint torque (muscle torque) resisting these stretches was computed from measurements of applied torque, acceleration and limb inertia. Electromyographic (EMG) responses in the triceps brachii (TB), brachialis (Br) and biceps brachii (BB) were monitored. 3. The EMG responses to sinusoidal stretches applied early in the movement were less than those responses to perturbations applied when the arm neared the target (especially in the antagonist muscle TB). These EMG responses caused fluctuations in the resistance to the perturbation (stiffness), as described below. 4. When the perturbation frequency was low (< 4 Hz) the resistance of the elbow muscles to the stretch increased as the arm approached the target (48% increase). In contrast, when the stretch frequency was 7 Hz the resistance decreased by 63%. This decrease can be explained by the increased reflex response, since at 7 Hz the reflex response is probably timed so that it assists, rather than resists, the stretching as a result of loop delays. This reflex timing was confirmed by observing that, after abruptly stopping the sinusoidal stretch, the reflex response persisted for 100 ms and was indeed in a direction that would have reduced the resistance, had the perturbation continued. 5. The time course of the net muscle stiffness was estimated for frequencies ranging from 4 to 8 Hz and for each 40 ms interval a Nyquist plot was constructed, forming a C-shaped curve as frequency was varied. The size of this curve gave a measure of the stiffness resulting from reflex activity. When the arm neared the target this reflexive stiffness reached a maximum, and was probably comparable in size to the intrinsic (non-reflexive) muscle stiffness. Also, in four of the five subjects the viscous component of stiffness at 7 Hz dropped significantly below zero when the arm neared the target, again indicating that at this frequency the reflex was large and acted inappropriately.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8006819

  7. Startle reactivity and anxiety disorders: aversive conditioning, context, and neurobiology

    Microsoft Academic Search

    Christian Grillon

    2002-01-01

    The aim of this article is to review studies on human anxiety using the startle reflex methodology and to apply the literature on context conditioning in rats to interpret the results. A distinction is made between cued fear (as in specific phobia), a phasic response to an explicit threat cue, and anxiety, a more sustained and future-oriented response not linked

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

    PubMed

    Mellon, DeForest; Hamid, Omer A Abdul

    2012-05-01

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

  9. Effect of contraction level and magnitude of stretch on tonic stretch reflex transmission characteristics.

    PubMed Central

    Neilson, P D; McCaughey, J

    1981-01-01

    Electromyogram tonic stretch reflex responses were recorded from biceps brachii muscles in normal and cerebral palsied subjects sustaining either 10% or 20% of maximum voluntary contraction and attempting to keep the elbow stiff in a fixed position. The muscle was stretch by a sinusoidal perturbation applied by the experimenter to the elbow angle. Five different amplitudes of stretch were employed ranging 1.67 to 10.0 degrees peak to peak variation of elbow angle. Spectral analysis of the rectified and filtered electromyogram revealed "noisy" sinusoidal reflex responses with negligible harmonic distortion but the amplitude of the reflex responses did not increase linearly with the amplitude of stretch. An analysis of variance showed that for both groups of subjects the gain of the tonic stretch reflex increased significantly (p less than 0.001) with contraction level and decreased significantly (p less than 0.001) with magnitude of stretch. This finding illustrates that both magnitude of stretch and level of contraction need to be carefully controlled when measures of tonic stretch reflex responses are used to assess changes of muscle tone. PMID:6278094

  10. Reflex jaw motions and jaw stiffness pertaining to whiplash injury of the neck.

    PubMed

    Christensen, L V; McKay, D C

    1997-07-01

    Because a so-called mandibular whiplash injury requires the absence of short-latency jaw-closing reflexes in order to explain the postulated mechanism of injury (excessive jaw opening); the authors studied the presence and absence and more importantly, the kinematics (duration, displacement, velocity, acceleration) of monosynaptic and possibly, polysynaptic myotatic (stretch) reflexes in the jaw elevator muscles. In six healthy adults jaw jerk maneuvers were elicited through a brisk tap on the chin, and surface electromyography identified elevator reflexes while translational electrognathography identified the kinematics of the reflexes. The maneuvers were done while maintaining the rest position (3% MVC) and moderate clenching of the teeth (30% MVC). Electromyography was also used to identify phasic elevator excitations during a passive brisk neck extension maneuver. A sudden and unexpected elongation of the jaw elevators released autogenic reflex responses that, in conjunction with augmented tissue elasticity (stiffness), elevated the mandible into centric occlusion within approximately 150 milliseconds. In 86% of trials, the responses occurred regardless of the prevailing resting and clenching contractile activities. There was no evidence of a depressor force that consistently would and could anchor the mandible in a position of extreme or moderate depression, the theoretical linchpin of the mandibular whiplash injury. It was concluded that the mandibular locomotor system is very efficient in maintaining the rest and intercuspal positions of the mandible. This study found no evidence corroborating the mechanism claimed to release a so-called mandibular whiplash injury. PMID:9586504

  11. Quantitative evaluation of the Myotatic Reflex in Hemiplegic and Paraplegic patients.

    PubMed

    Zamparo; Capelli; Pagliaro; De Luca G; Pertoldi; Saccavini; Di Prampero PE

    1997-01-01

    The aim of this study was the quantitative evaluation of the myotatic reflex in a group of 11 subjects affected by spastic paresis of the lower limbs (8 hemiplegic and 3 paraplegic patients) and, for comparison, in a group of 7 healthy subjects. The parameters taken into account were the gain of the reflex and the time delay between the input and the mechanical output. The gain was calculated as the ratio between: i) the peak value of the input force (FPH) measured by means of an instrumented hammer with which the patellar tendon was hit; and ii) the peak value of the corresponding reflex force of the quadriceps femoris (FPQ) measured by means of a load cell connected to the subject's ankle. The gain of the reflex (FPQ/FPH) was found to be 1.9 to 2.4 times larger in patients as compared to control subjects and, among the patients to be twice at low, as compared to high, levels of stimulation. Among the hemiplegic patients, significant differences were found in the time delay of the response between the affected and unaffected limbs. Since both the intensity of the reflex and its gain were found to depend on the mechanical energy input, both parameters must be taken in to account if a diagnosis of spasticity has to be made. PMID:10352468

  12. Acute Whole-Body Vibration does not Facilitate Peak Torque and Stretch Reflex in Healthy Adults

    PubMed Central

    Yeung, Ella W.; Lau, Cheuk C.; Kwong, Ada P.K.; Sze, Yan M.; Zhang, Wei Y.; Yeung, Simon S.

    2014-01-01

    The acute effect of whole-body vibration (WBV) training may enhance muscular performance via neural potentiation of the stretch reflex. The purpose of this study was to investigate if acute WBV exposure affects the stretch induced knee jerk reflex [onset latency and electromechanical delay (EMD)] and the isokinetic knee extensor peak torque performance. Twenty-two subjects were randomly assigned to the intervention or control group. The intervention group received WBV in a semi-squat position at 30° knee flexion with an amplitude of 0.69 mm, frequency of 45 Hz, and peak acceleration of 27.6 m/s2 for 3 minutes. The control group underwent the same semii-squatting position statically without exposure of WBV. Two-way mixed repeated measures analysis of variance revealed no significant group effects differences on reflex latency of rectus femoris (RF) and vastus lateralis (VL; p = 0.934 and 0.935, respectively) EMD of RF and VL (p = 0.474 and 0.551, respectively) and peak torque production (p = 0.483) measured before and after the WBV. The results of this study indicate that a single session of WBV exposure has no potentiation effect on the stretch induced reflex and peak torque performance in healthy young adults. Key Points There is no acute potentiation of stretch reflex right after whole body vibration. Acute whole body vibration does not improve mus-cle peak torque performance in healthy young adults. PMID:24570602

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

    PubMed

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

    2012-04-01

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

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

    PubMed

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

    2014-12-01

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

  15. Effect of stimulus size and luminance on the rod-, cone-, and melanopsin-mediated pupillary light reflex.

    PubMed

    Park, Jason C; McAnany, J Jason

    2015-01-01

    This study determined if the pupillary light reflex (PLR) driven by brief stimulus presentations can be accounted for by the product of stimulus luminance and area (i.e., corneal flux density, CFD) under conditions biased toward the rod, cone, and melanopsin pathways. Five visually normal subjects participated in the study. Stimuli consisted of 1-s short- and long-wavelength flashes that spanned a large range of luminance and angular subtense. The stimuli were presented in the central visual field in the dark (rod and melanopsin conditions) and against a rod-suppressing short-wavelength background (cone condition). Rod- and cone-mediated PLRs were measured at the maximum constriction after stimulus onset whereas the melanopsin-mediated PLR was measured 5-7 s after stimulus offset. The rod- and melanopsin-mediated PLRs were well accounted for by CFD, such that doubling the stimulus luminance had the same effect on the PLR as doubling the stimulus area. Melanopsin-mediated PLRs were elicited only by short-wavelength, large (>16°) stimuli with luminance greater than 10 cd/m(2), but when present, the melanopsin-mediated PLR was well accounted for by CFD. In contrast, CFD could not account for the cone-mediated PLR because the PLR was approximately independent of stimulus size but strongly dependent on stimulus luminance. These findings highlight important differences in how stimulus luminance and size combine to govern the PLR elicited by brief flashes under rod-, cone-, and melanopsin-mediated conditions. PMID:25788707

  16. Effect of stimulus size and luminance on the rod-, cone-, and melanopsin-mediated pupillary light reflex

    PubMed Central

    Park, Jason C.; McAnany, J. Jason

    2015-01-01

    This study determined if the pupillary light reflex (PLR) driven by brief stimulus presentations can be accounted for by the product of stimulus luminance and area (i.e., corneal flux density, CFD) under conditions biased toward the rod, cone, and melanopsin pathways. Five visually normal subjects participated in the study. Stimuli consisted of 1-s short- and long-wavelength flashes that spanned a large range of luminance and angular subtense. The stimuli were presented in the central visual field in the dark (rod and melanopsin conditions) and against a rod-suppressing short-wavelength background (cone condition). Rod- and cone-mediated PLRs were measured at the maximum constriction after stimulus onset whereas the melanopsin-mediated PLR was measured 5–7 s after stimulus offset. The rod- and melanopsin-mediated PLRs were well accounted for by CFD, such that doubling the stimulus luminance had the same effect on the PLR as doubling the stimulus area. Melanopsin-mediated PLRs were elicited only by short-wavelength, large (>16°) stimuli with luminance greater than 10 cd/m2, but when present, the melanopsin-mediated PLR was well accounted for by CFD. In contrast, CFD could not account for the cone-mediated PLR because the PLR was approximately independent of stimulus size but strongly dependent on stimulus luminance. These findings highlight important differences in how stimulus luminance and size combine to govern the PLR elicited by brief flashes under rod-, cone-, and melanopsin-mediated conditions. PMID:25788707

  17. Age-related changes in human vestibulo-ocular and optokinetic reflexes: Pseudorandom rotation tests

    NASA Technical Reports Server (NTRS)

    Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

    1989-01-01

    The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters which describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year.

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

    PubMed Central

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

    2008-01-01

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

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

    PubMed

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

    2008-06-01

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

  20. Changes in the stretch reflex of the human first dorsal interosseous muscle during different tasks.

    PubMed Central

    Doemges, F; Rack, P M

    1992-01-01

    1. Subjects flexed the interphalangeal joint of the index finger against a lever which was mounted on the shaft of a torque motor. 2. There were two different tasks. In one, the subject attempted to maintain a constant finger position in the face of changing forces, whereas in the other the subject attempted to maintain a constant force while the motor moved the lever. 3. Each of the tasks was interrupted by ramp extensions. These evoked stretch reflexes which were recorded in the first dorsal interosseous (FDI) muscle electromyogram (EMG). 4. Long-latency (55-90 ms) reflex responses were larger during the 'maintain position' task than during the 'maintain force' task, although the ramp extensions began from a similar finger position, a similar flexing force, and with a similar amount of FDI EMG activity. 5. It is concluded that the nature of the task has an effect on the magnitude of the long-latency stretch reflex. PMID:1593460

  1. [The circulation of reflexes in brain research, art and technology. Introductory remarks].

    PubMed

    Wübben, Yvonne; Vöhringer, Margarete

    2009-03-01

    The introduction deals with two main issues: First, it focuses on the question why a history of scientific concepts should not be limited to the analysis of scientific texts alone. Secondly, it shows how the history of the reflex concept gains from looking at various fields such as art, literature and brain research. The crucial role the reflex played in 19th and 20th century and the different meanings it adopted allowed us to conclude with Bruno Latour that the distinction between art and science is in itself historical. Thus, the distinction proves to be of little use for the historiography of complex concepts such as the reflex which rarely appear to be purely scientific. PMID:19824304

  2. Myotatic reflexes and the on-off effect in patients with Parkinson's disease.

    PubMed

    Dufresne, J R; Soechting, J F; Tolosa, E S

    1981-04-01

    Reflex activity in the biceps and triceps muscles evoked by applied torque perturbations was studied in patients with Parkinson's disease. The perturbations consisted of single pulses or of pseudo-random sequences of pulses of torque. The patients were treated with levodopa and some exhibited marked fluctuations in their clinical disabilities ("on-off" effect). The study was undertaken to see if reflex activity changed in parallel with the fluctuations of their clinical symptoms. It was found that the reflex activity in these patients could be classified into two types, a Type I response differing little from normal and a Type II response exhibiting marked high-frequency (8-14 Hz) oscillations in EMG activity. Both Type I and Type II responses were virtually the same in the "on" as in the "off" state. PMID:7241159

  3. Affective modulation of the startle eyeblink and postauricular reflexes in autism spectrum disorder.

    PubMed

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

    2010-07-01

    Eyeblink and postauricular reflexes to standardized affective images were examined in individuals without (n = 37) and with (n = 20) autism spectrum disorders (ASDs). Affective reflex modulation in control participants replicated previous findings. The ASD group, however, showed anomalous reflex modulation patterns, despite similar self-report ratings of pictures. Specifically, the ASD group demonstrated exaggerated eyeblink responses to pleasant images and exaggerated postauricular responses to unpleasant images. Although ASD is often conceptualized in terms of specific deficits in affective responding in the social domain, the present results suggest a domain-general pattern of deficits in affective processing and that such deficits may arise at an early phase in the stream of information processing. PMID:20049632

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

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Brandt, T.

    1993-01-01

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

  5. Associations between prefrontal cortex activation and H-reflex modulation during dual task gait.

    PubMed

    Meester, Daan; Al-Yahya, Emad; Dawes, Helen; Martin-Fagg, Penny; Piñon, Carmen

    2014-01-01

    Walking, although a largely automatic process, is controlled by the cortex and the spinal cord with corrective reflexes modulated through integration of neural signals from central and peripheral inputs at supraspinal level throughout the gait cycle. In this study we used an additional cognitive task to interfere with the automatic processing during walking in order to explore the neural mechanisms involved in healthy young adults. Participants were asked to walk on a treadmill at two speeds, both with and without additional cognitive load. We evaluated the impact of speed and cognitive load by analyzing activity of the prefrontal cortex (PFC) using functional Near-Infrared Spectroscopy (fNIRS) alongside spinal cord reflex activity measured by soleus H-reflex amplitude and gait changes obtained by using an inertial measuring unit. Repeated measures ANOVA revealed that fNIRS Oxy-Hb concentrations significantly increased in the PFC with dual task (walking while performing a cognitive task) compared to a single task (walking only; p < 0.05). PFC activity was unaffected by increases of walking speed. H-reflex amplitude and gait variables did not change in response to either dual task or increases in walking speed. When walking under additional cognitive load participants adapted by using greater activity in the PFC, but this adaptation did not detrimentally affect H-reflex amplitude or gait variables. Our findings suggest that in a healthy young population central mechanisms (PFC) are activated in response to cognitive loads but that H-reflex activity and gait performance can successfully be maintained. This study provides insights into the mechanisms behind healthy individuals safely performing dual task walking. PMID:24600375

  6. Effects of sufentanil and NMDA antagonists on a C-fibre reflex in the rat

    PubMed Central

    Adam, Frédéric; Gairard, Anne Cécile; Chauvin, Marcel; Bars, Daniel Le; Guirimand, Frédéric

    2001-01-01

    The effects of intravenous sufentanil and pre-administration of N-methyl-D-aspartate (NMDA) receptor antagonists were tested on a reflex triggered by C-fibre activation. The reflex was elicited by electrical stimulation of the sural nerve and recorded from the ipsilateral biceps femoris muscle in halothane anaesthetized rats either (1) with an intact neuraxis or (2) in which the brain had previously been transected at the level of the obex.All four doses of sufentanil (0.33, 0.6, 1 and 2??g?kg?1) elicited a depression of the reflex in a dose-dependent manner. However, following the expected depression, all doses of sufentanil elicited both facilitation of the reflex and tonic inter-stimulus discharges.The C-fibre reflex was not modified following intravenous ketamine (1?mg?kg?1) or (+)-HA966 (5 or 10?mg?kg?1) but, when administered 5?min before sufentanil, these drugs enhanced both the extent and the duration of the depression and strongly reduced the facilitations.In the obex-transected rats, the depressive effect of 1??g?kg?1 sufentanil increased, while the facilitation of the C-fibre reflex and the tonic inter-stimulus discharges disappeared. Pre-administration of 10?mg?kg?1 (+)-HA966 reinforced and prolonged the depressive effect of sufentanil.These results extend previous studies suggesting the involvement of NMDA receptors in the spinal transmission of nociceptive signals. They illustrate the potential of spinal NMDA receptor blockade to both enhance the analgesic, and prevent the pro-nociceptive, effects of sufentanil. PMID:11487510

  7. Behaviour of short and long latency reflexes in fatigued human muscles.

    PubMed Central

    Duchateau, J; Hainaut, K

    1993-01-01

    1. The human abductor pollicis brevis (APB) and first dorsal interosseus (FDI) were fatigued by sustained maximal voluntary contractions and, in the case of the APB also by electrically induced (30 Hz) contractions, until the loss of force reached 50% of control. The short latency or Hoffmann reflex (H reflex) and the long latency reflex (LLR) were evoked during weak voluntary contractions by the electrical stimulation of the median nerve at the wrist in control, during and after the fatigue experiments. 2. As compared to control, the normalized H reflex amplitude in the two fatigue modalities was found to have decreased by 30% without any significant change in the LLR. This finding and the observation that the LLR was enhanced by 46% in simultaneous recordings, in which the APB remained at rest during FDI fatigue, could be explained by a stronger descending fatigue-induced central drive which spreads to neighbouring non-fatigued muscles. 3. A comparison of the H reflex and the LLR behaviour during fatigue indicates that motoneurone activation threshold is not affected but that changes in peripheral drive are present, which possibly induce presynaptic inhibition of Ia afferents and/or inhibition of interneurones in the oligosynaptic pathways. Our observation of a rather slow time course for the H reflex decrease during fatigue supports the point of view that these inhibitions are activated by metabolic and/or chemical changes in the fatigued muscle. 4. It is concluded from the results of this study that muscle fatigue induces an enhanced descending supraspinal drive which compensates for a loss of excitation from the peripheral afferents on motoneurones. PMID:8120833

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

    PubMed Central

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

    2014-01-01

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

  9. Associations between prefrontal cortex activation and H-reflex modulation during dual task gait

    PubMed Central

    Meester, Daan; Al-Yahya, Emad; Dawes, Helen; Martin-Fagg, Penny; Piñon, Carmen

    2014-01-01

    Walking, although a largely automatic process, is controlled by the cortex and the spinal cord with corrective reflexes modulated through integration of neural signals from central and peripheral inputs at supraspinal level throughout the gait cycle. In this study we used an additional cognitive task to interfere with the automatic processing during walking in order to explore the neural mechanisms involved in healthy young adults. Participants were asked to walk on a treadmill at two speeds, both with and without additional cognitive load. We evaluated the impact of speed and cognitive load by analyzing activity of the prefrontal cortex (PFC) using functional Near-Infrared Spectroscopy (fNIRS) alongside spinal cord reflex activity measured by soleus H-reflex amplitude and gait changes obtained by using an inertial measuring unit. Repeated measures ANOVA revealed that fNIRS Oxy-Hb concentrations significantly increased in the PFC with dual task (walking while performing a cognitive task) compared to a single task (walking only; p < 0.05). PFC activity was unaffected by increases of walking speed. H-reflex amplitude and gait variables did not change in response to either dual task or increases in walking speed. When walking under additional cognitive load participants adapted by using greater activity in the PFC, but this adaptation did not detrimentally affect H-reflex amplitude or gait variables. Our findings suggest that in a healthy young population central mechanisms (PFC) are activated in response to cognitive loads but that H-reflex activity and gait performance can successfully be maintained. This study provides insights into the mechanisms behind healthy individuals safely performing dual task walking. PMID:24600375

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

    PubMed Central

    Lilaonitkul, Watjana

    2012-01-01

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

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

    PubMed

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

    2014-07-01

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

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

    PubMed Central

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

    2012-01-01

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

  13. The interaction between the central and peripheral nervous systems in the mediation of gill withdrawal reflex behavior in Aplysia

    Microsoft Academic Search

    Ken Lukowiak; Bertram Peretz

    1977-01-01

    We studied the relationship between the peripheral and central nervous system in mediating the gill withdrawal reflex. The central and peripheral nervous systems which mediate the gill withdrawal reflex interact and are parts of an integrated nervous system. The PNS initiates and mediates the behavior in the absence of the CNS. When the CNS is present, it bestows greater adaptability

  14. Spinal reflexes and the concentrations of 5HIAA, MHPG, and HVA in lumbar cereborspinal fluid after spinal lesions in man

    Microsoft Academic Search

    P Ashby; M Verrier; J J Warsh; K S Price

    1976-01-01

    Descending bulbospinal pathways that employ specific neurotransmitter substances are known to be capable of modulating segmental reflex activity in the experimental animal. To determine whether this might also occur in man correlations have been sought between the activity in spinal reflex pathways and the lumbar cerebrospinal fluid (CSF) concentrations of 5-hydroxyindolacetic acid (5-HIAA), 3 methoxy-4-hydroxyphenylglycol (MHPG), and homovanillic acid (HVA)

  15. THE EXOSKELETON AND INSECT PROPRIOCEPTION II. REFLEX EFFECTS OF TIBIAL CAMPANIFORM SENSILLA IN THE AMERICAN COCKROACH, PERIPLANETA AMERICANA

    Microsoft Academic Search

    SASHA N. ZILL; DAVID T. MORAN; FRANCISCO G. VARELA

    SUMMARY 1. Mechanical stimulation of individual tibia! campaniform sensilla produces specific reflex effects upon motoneurones to leg muscles. 2. The reflex effects of a campaniform sensillum depend upon the orientation of its cuticular cap. The proximal sensilla, oriented perpendicular to the long axis of the tibia, excite slow motoneurones to the extensor tibiae and extensor trochanteris muscles and inhibit slow

  16. Trigeminocardiac reflex in a child during pre-Onyx DMSO injection for juvenile nasopharyngeal angiofibroma embolization. A case report.

    PubMed

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

    2011-03-01

    We describe the occurrence of the trigeminocardiac reflex (TCR) during DMSO pre-flushing of the microcatheter in preparation for Onyx embolization via the internal maxillary artery. TCR has not been previously associated with embolization of extradural entities. Familiarity with this clinical reflex and its proper management may help in planning neurointerventional procedures involving DMSO injection in the trigeminal territory. PMID:21561553

  17. The whole-body shortening reflex of the medicinal leech: motor pattern, sensory basis, and interneuronal pathways

    Microsoft Academic Search

    B. K. Shaw; W. B. Kristan Jr

    1995-01-01

    The leech whole-body shortening reflex consists of a rapid contraction of the body elicited by a mechanical stimulus to the anterior of the animal. We used a variety of reduced preparations — semi-intact, body wall, and isolated nerve cord — to begin to elucidate the neural basis of this reflex in the medicinal leech Hirudo medicinalis. The motor pattern of

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

    ERIC Educational Resources Information Center

    Abraham, John

    2008-01-01

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

  19. Comparative studies of the effects of some antimuscarinic agents on gastric damage and pupillary reflex in the rat.

    PubMed Central

    Daniotti, S.; Del Soldato, P.

    1984-01-01

    The effects of some antimuscarinic compounds on oxotremorine-induced gastric damage, the pupil size and the pupillary light reflex have been studied in the rat. Unlike atropine, propantheline and methylscopolamine, pirenzepine is effective in preventing gastric erosions at doses much lower than those that affect pupillary reflex. PMID:6547361

  20. The effects of catalase inhibition into the fourth cerebral ventricle on the Bezold-Jarisch reflex in spontaneously hypertensive rats.

    PubMed

    Cisternas, José Raul; Valenti, Vitor E; Sato, Monica A; Fonseca, Fernando L A; Saldiva, Paulo H N; De Mello Monteiro, Carlos B; Neto, Modesto Leite Rolim; Rodrigues, Luciano M R; De Abreu, Luiz Carlos

    2011-12-01

    Many studies have investigated the role of oxidative stress on cardiovascular system in the brainstem of spontaneously hypertensive rats (SHR). However, we do not know yet if catalase inhibition influences cardiopulmonary reflex (Bezol-Jarisch reflex). Thus, we aimed to evaluate the effects of central catalase inhibition on cardiopulmonary reflex in SHR. Males Wistar Kyoto (WKY) rats and SHR were implanted with a stainless steel guide cannula into the fourth cerebral ventricle (4th V). The femoral artery and vein were cannulated for mean arterial pressure (MAP) and heart rate (HR) measurement and drug infusion, respectively. The cardiopulmonary reflex was tested with phenylbiguanide (PBG, 8 ?g/kg, bolus, i.v.). Cardiopulmonary reflex was evaluated before and 15 minutes after 3-amino-1,2,4-triazole (ATZ, 0.01 g/100 ?L) injection into the 4th V. Vehicle treatment did not change basal MAP and HR and cardiopulmonary reflex responses in SHR and WKY rats. Central ATZ increased hypotensive (p=0.038) responses without influencing the bradycardic reflex (p=0.287) in WKY rats. In SHR, ATZ increased hypotension (p=0.0004) and bradycardic (p=0.04) responses to i.v. PBG. No changes were observed regarding basal MAP and HR after ATZ injection in SHR and WKY rats. We suggest central catalase inhibition affects cardiopulmonary reflex with more intensity in SHR compared to WKY rats. PMID:22262536

  1. The use of acupuncture in controlling the gag reflex in patients requiring an upper alginate impression: an audit

    Microsoft Academic Search

    M Bundgaard; J Fiske; A M L Pedersen; P Rosted

    2006-01-01

    Background A pronounced gag reflex (GR) can be a problem to both the acceptance and delivery of dental treatment. Despite a range of management strategies, some patients cannot accept even simple dental treatment. The aim of this study was to evaluate the use of acupuncture point CV-24 in controlling a profound gag reflex during dental treatment requiring an upper alginate

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

    E-print Network

    Kleinfeld, David

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

  3. Addressing Uncomfortable Issues: Reflexivity as a Tool for Culturally Safe Practice in Aboriginal and Torres Strait Islander Health

    ERIC Educational Resources Information Center

    Wilson, Annabelle

    2014-01-01

    It is well recognised that research with Aboriginal communities needs to be ethical, meaningful and useful, in a way that is defined by communities themselves. This article provides an example of how reflexivity, from a number of positions and paradigms, can be used to undertake such research. I used a reflexive journal to document and critically…

  4. Afferent signals from the extraocular muscles affect the gain of the horizontal vestibulo-ocular reflex in the alert pigeon

    Microsoft Academic Search

    I. M. L Donaldson; P. C Knox

    2000-01-01

    We have shown previously that the gain of the horizontal vestibulo-ocular reflex (HVOR) is modified by afferent signals from extraocular muscle proprioceptors in the decerebrate pigeon. We have now analysed the variability of the HVOR in intact, alert pigeons and, using the artificial vestibulo-ocular reflex method, have found that in all of the pigeons tested afferent signals from the extraocular

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  6. The conjugacy of the vestibulo-ocular reflex evoked by single labyrinth stimulation in awake monkeys.

    PubMed

    Tang, Xuehui; Xu, Youguo; Simpson, Ivra; Jeffcoat, Ben; Mustain, William; Zhou, Wu

    2010-10-01

    It is well known that the vestibulo-ocular reflex (VOR) is conjugate when measured in the dark with minimal vergence. But the neural basis of the VOR conjugacy remains to be identified. In the present study, we measured the VOR conjugacy during single labyrinth stimulation to examine whether the VOR conjugacy depends on reciprocal stimulation of the two labyrinths. There are conflicting views on this issue. First, since the vestibular signals carried by the ascending tract of Deiters' are distributed exclusively to the motoneurons of the ipsilateral eye, the neural innervations after single labyrinth stimulation are not symmetrical for the two eyes. Thus, single labyrinth stimulation may generate disjunctive VOR responses. Second, the only published study on this issue was an electrooculography (EOG) study that reported disjunctive VOR responses during unilateral caloric irrigation (Wolfe in Ann Otol 88:79-85, 1979). Third, the VOR during unilateral caloric stimulation performed in clinical vestibular tests is routinely perceived to be conjugate. To resolve these conflicting views, the present study examined the VOR conjugacy during single labyrinth stimulation by recording binocular eye position signals in awake monkeys with a search coil technique. In contradiction to the previous EOG study and the prediction based on the asymmetry of the unilateral brainstem VOR circuits, we found that the VOR during unilateral caloric irrigation was conjugate over a wide range of conditions. We conclude that the net neural innervations received by the two eyes are symmetrical after single labyrinth stimulation, despite the apparent asymmetry in the unilateral VOR pathways. A novel role for the ascending tract of Deiters' in the VOR conjugacy is proposed. PMID:20820761

  7. Iron Deficiency with or without Anemia Impairs Prepulse Inhibition of the Startle Reflex

    PubMed Central

    Pisansky, Marc T.; Wickham, Robert J.; Su, Jianjun; Fretham, Stephanie; Yuan, Li-Lian; Sun, Mu; Gewirtz, Jonathan C.; Georgieff, Michael K.

    2013-01-01

    Iron deficiency (ID) during early life causes long-lasting detrimental cognitive sequelae, many of which are linked to alterations in hippocampus function, dopamine synthesis, and the modulation of dopaminergic circuitry by the hippocampus. These same features have been implicated in the origins of schizophrenia, a neuropsychiatric disorder with significant cognitive impairments. Deficits in sensorimotor gating represent a reliable endophenotype of schizophrenia that can be measured by prepulse inhibition (PPI) of the acoustic startle reflex. Using two rodent model systems, we investigated the influence of early-life ID on PPI in adulthood. To isolate the role of hippocampal iron in PPI, our mouse model utilized a timed (embryonic day 18.5), hippocampus-specific knockout of Slc11a2, a gene coding an important regulator of cellular iron uptake, the divalent metal transport type 1 protein (DMT-1). Our second model used a classic rat dietary-based global ID during gestation, a condition that closely mimics human gestational ID anemia (IDA). Both models exhibited impaired PPI in adulthood. Furthermore, our DMT-1 knockout model displayed reduced long-term potentiation (LTP) and elevated paired pulse facilitation (PPF), electrophysiological results consistent with previous findings in the IDA rat model. These results, in combination with previous findings demonstrating impaired hippocampus functioning and altered dopaminergic and glutamatergic neurotransmission, suggest that iron availability within the hippocampus is critical for the neurodevelopmental processes underlying sensorimotor gating. Ultimately, evidence of reduced PPI in both of our models may offer insights into the roles of fetal ID and the hippocampus in the pathophysiology of schizophrenia. PMID:23733517

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

    PubMed Central

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

    2007-01-01

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

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

    PubMed Central

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

    2007-01-01

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

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

    SciTech Connect

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

    1985-03-01

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

  11. Mayo and NINDS scales for assessment of tendon reflexes: between observer agreement and implications for communication

    PubMed Central

    Manschot, S; van Passel, L; Buskens, E; Algra, A; van Gijn, J

    1998-01-01

    The purpose of this study was to assess the between observer reliability of two standard notation scales for grading tendon reflexes, The Mayo Clinic scale and the NINDS scale. In a university department of neurology two or three physicians judged the biceps, triceps, knee, and ankle tendon reflexes in two groups of 50 patients using either scale. The interobserver agreement was assessed by means of ? statistics. The agreement among doctors was never better than "fair" for both scales (highest ? value 0.35). A verbal description rather than a codified scale may improve communication among doctors.?? PMID:9489542

  12. Weight systems for toric Calabi-Yau varieties and reflexivity of Newton polyhedra

    E-print Network

    Harald Skarke

    1996-03-07

    According to a recently proposed scheme for the classification of reflexive polyhedra, weight systems of a certain type play a prominent role. These weight systems are classified for the cases $n=3$ and $n=4$, corresponding to toric varieties with K3 and Calabi--Yau hypersurfaces, respectively. For $n=3$ we find the well known 95 weight systems corresponding to weighted $\\IP^3$'s that allow transverse polynomials, whereas for $n=4$ there are 184026 weight systems, including the 7555 weight systems for weighted $\\IP^4$'s. It is proven (without computer) that the Newton polyhedra corresponding to all of these weight systems are reflexive.

  13. Caloric stimulation-induced augmentation of H-reflexes in normal subjects, but not in spinal cord-injured patients.

    PubMed

    Raffensperger, M; York, D H

    1984-05-01

    This study examined the effects of ice water caloric stimulation on H-reflex amplitude in normal subjects and three complete spinal cord-injured patients. H-reflexes were obtained by stimulating the tibial nerve at the popliteal fossa and recording the H-response from the gastrocnemius muscle. All normal subjects who experienced nystagmus or vertigo demonstrated significant augmentation in H-reflex amplitude with ice water irrigation of the ear canal. In the three spinal cord-injured patients, there was no significant change of H-reflex with the ice water stimulus. The results suggest that descending tracts in the anterior spinal cord must be functional to demonstrate caloric augmentation of H-reflexes. In patients with spinal cord injury, it may be possible to predict the recovery of motor function using this test together with other clinical signs of neurological function. PMID:6728162

  14. FUNCTIONAL ORGANIZATION IN THE TERMINAL SEGMENTS OF THE SPINAL CORD WITH A CONSIDERATION OF CENTRAL EXCITATORY AND INHIBITORY LATENCIES IN MONOSYNAPTIC REFLEX SYSTEMS

    Microsoft Academic Search

    DAVID P. C. LLOYD; VICTOR J. WILSON

    1959-01-01

    Prominent monosynaptic and disynaptic reflex discharges characterize ipsilateral reflex transmission in the third sacral segment. Convergence upon the motoneurons from the two sides of the body is inhibitory, that through disynaptic paths excitatory. The relative latencies of excitation and inhibition of reflex responses, of excitatory and inhibitory synaptie potentials, and of various aspects of impulse discharge in motoneurons are considered.

  15. The Inter-Reflexive Possibilities of Dual Observations: An Account from and through Experience

    ERIC Educational Resources Information Center

    Barrett, Margaret S.; Mills, Janet

    2009-01-01

    In this article, we explore the methodological possibilities of dual observation and "inter-reflexive" interpretation as we have experienced this in a longitudinal ethnographic case study of music teaching and learning in an English cathedral choir school. Our intent here is to understand the ways in which our particular historical, social and…

  16. Distributed parallel processing in the vertical vestibulo-ocular reflex: Learning networks compared to tensor theory

    Microsoft Academic Search

    T. J. Anastasio; D. A. Robinson

    1990-01-01

    The vestibulo-ocular reflex (VOR) is capable of producing compensatory eye movements in three dimensions. It utilizes the head rotational velocity signals from the semicircular canals to control the contractions of the extraocular muscles. Since canal and muscle coordinate frames are not orthogonal and differ from one another, a sensorimotor transformation must be produced by the VOR neural network. Tensor theory

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

  18. "Hearing the Country": Reflexivity as an Intimate Journey into Epistemological Liminalities

    ERIC Educational Resources Information Center

    Bradley, John

    2012-01-01

    In this article I discuss the way Problem-Based Learning (PBL) and reflexivity is employed in a university environment to address the question of how we can most successfully transfer knowledge about the presumed Other into our own cultural space without reducing, fragmenting, and exoticising complex knowledge systems. My goal is to stimulate in…

  19. Genetic Influence on Slope Variability in a Childhood Reflexive Attention Task

    PubMed Central

    Lundwall, Rebecca A.; Watkins, Jeffrey K.

    2015-01-01

    Individuals are not perfectly consistent, and interindividual variability is a common feature in all varieties of human behavior. Some individuals respond more variably than others, however, and this difference may be important to understanding how the brain works. In this paper, we explore genetic contributions to response time (RT) slope variability on a reflexive attention task. We are interested in such variability because we believe it is an important part of the overall picture of attention that, if understood, has the potential to improve intervention for those with attentional deficits. Genetic association studies are valuable in discovering biological pathways of variability and several studies have found such associations with a sustained attention task. Here, we expand our knowledge to include a reflexive attention task. We ask whether specific candidate genes are associated with interindividual variability on a childhood reflexive attention task in 9–16 year olds. The genetic makers considered are on 11 genes: APOE, BDNF, CHRNA4, COMT, DRD4, HTR4, IGF2, MAOA, SLC5A7, SLC6A3, and SNAP25. We find significant associations with variability with markers on nine and we discuss the results in terms of neurotransmitters associated with each gene and the characteristics of the associated measures from the reflexive attention task. PMID:26102342

  20. Soleus H-reflex phase-dependent modulation is preserved during stepping within a robotic exoskeleton

    Microsoft Academic Search

    Maria Knikou; Nupur Hajela; Chaithanya K. Mummidisetty; Ming Xiao; Andrew C. Smith

    2011-01-01

    ObjectiveTo investigate to what extent the phase-dependent modulation of the soleus H-reflex is preserved when bilateral leg movements are electromechanically driven by a robotic exoskeleton at different levels of body weight support (BWS) in healthy subjects.

  1. The Role of Pragmatics in Reflexive Interpretation by Turkish Learners of English.

    ERIC Educational Resources Information Center

    Demirci, Mahide

    2000-01-01

    Investigates the effects of pragmatic principles on the acquisition of the binding of English reflexives by adult Turkish second language (L2) learners. Compares pragmatically-biased and pragmatically-neutral sentences to determine whether pragmatic bias towards a non-local antecedent overrides the parameter setting of English and causes learners…

  2. The Role of Pragmatics in the Acquisition of Reflexive Binding in L2.

    ERIC Educational Resources Information Center

    Demirci, Mahide

    1997-01-01

    Investigated the effects of pragmatic constraints on the acquisition of the binding of English reflexives by adult Turkish second-language learners. Pragmatically-biased and pragmatically-neutral sentences were compared to determine whether pragmatic bias towards a non-local antecedent overrides the parameter setting of English and causes learners…

  3. EVALUATION OF SENSORY SYSTEM FUNCTION USING REFLEX MODIFICATION OF THE STARTLE RESPONSE

    EPA Science Inventory

    Methods to measure damage to sensory systems following toxicant exposure vary from rapid and subjective tests (e.g., pinna reflex) to time-consuming and objective tests (e.g., psychophysical tests). eflex modification of the startle response represents an alternative technique in...

  4. Investigating Hemispheric Lateralization of Reflexive Attention to Gaze and Arrow Cues

    ERIC Educational Resources Information Center

    Marotta, Andrea; Lupianez, Juan; Casagrande, Maria

    2012-01-01

    Recent studies have demonstrated that central cues, such as eyes and arrows, reflexively trigger attentional shifts. However, it is not clear whether the attentional mechanisms induced by these two cues are similar or rather differ in some important way. We investigated hemispheric lateralization of the orienting effects induced by the two cue…

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Fan, Xiaofei; Miles, Judith H.; Takahashi, Nicole; Yao, Gang

    2009-01-01

    Computerized binocular infrared pupillography was used to measure the transient pupillary light reflex (PLR) in both children with autism spectrum disorders (ASDs) and children with typical development. We found that participants with ASDs showed significantly longer PLR latency, smaller constriction amplitude and lower constriction velocity than…

  7. Evolution, Psychology, and John Dewey's Critique of the Reflex Arc Concept.

    ERIC Educational Resources Information Center

    Bredo, Eric

    1998-01-01

    Discusses Dewey's article on the reflex arc concept as critique of mechanistic approaches to psychology and suggestion for an approach based on evolutionary assumptions. Maintains that the resulting psychology gave an integrated way of understanding the relation between organism and environment, and cognition and behavior; the work anticipated…

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

    ERIC Educational Resources Information Center

    McGuinness, Seamus; Sloane, Peter J.

    2011-01-01

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

  9. Post-Stop-Signal Slowing: Strategies Dominate Reflexes and Implicit Learning

    E-print Network

    Logan, Gordon D.

    Post-Stop-Signal Slowing: Strategies Dominate Reflexes and Implicit Learning Patrick G. Bissett demands. One task that is well-suited to explore control adjustments is the stop-signal paradigm, in which subjects must balance initiation and inhibition. One common adjustment in the stop-signal paradigm is post-stop-signal

  10. Desensitization of the cough reflex during limb muscle contraction in anesthetized rabbits.

    PubMed

    Poussel, Mathias; Bosser, Gilles; Varechova, Silvia; Demoulin, Bruno; Chalon, Bernard; Ruckebusch, Odile; Tiotiu, Angelica; Renaud, Pierre; Schweitzer, Cyril; Chenuel, Bruno

    2014-02-01

    The 'cough network' exhibits plasticity at the sensor and integration levels leading to modulation of the strength or pattern of the cough reflex. Little is known about the interactions between cough and human activities, especially during exercise. The present study was designed to determine whether exercise, mimicked by electrically induced muscle contractions, can modify the incidence and/or strength of cough following mechanical stimulation of the trachea in anesthetized rabbits. Thirteen anesthetized, tracheotomized rabbits were studied by a total of 311 tracheal stimulations: 196 at rest and 115 during exercise. During muscle contractions, the incidence of the cough reflex (CR) decreased and the expiration reflex (ER) increased (p < 0.0001). The sensitivity of the CR and ER both decreased during exercise compared to the sensitivity of the CR at rest (p < 0.02), while the strength of the expulsive response remained unchanged. These results indicate that adjustments occurring during muscle contractions likely downregulate tracheal defensive reflexes in anesthetized rabbits. PMID:23891778

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

    E-print Network

    2005-01-01

    thresholds and are greater in magnitude, resulting clinically in spasticity and spasms. Reflexes may also. For instance, the Babinski sign, which consists of the activation of the extensor hallucis longus muscle ob- served in chronic human SCI. Indeed, it has been suggested that flexor spasms, which are common

  12. Autoethnography as a Method for Reflexive Research and Practice in Vocational Psychology

    ERIC Educational Resources Information Center

    McIlveen, Peter

    2008-01-01

    This paper overviews the qualitative research method of autoethnography and its relevance to research in vocational psychology and practice in career development. Autoethnography is a reflexive means by which the researcher-practitioner consciously embeds himself or herself in theory and practice, and by way of intimate autobiographic account,…

  13. Effects of Cultured Adrenal Chromaffin Cell Implants on Hindlimb Reflexes of the 6-OHDA Lesioned Rat

    PubMed Central

    Pulford, Bruce E.; Mihajlov, Andrea R.; Nornes, Howard O.; Whalen, L. Ray

    1994-01-01

    The effects of implantation of cultured adrenal medullary cells on the recovery of neurotransmitter specific reflex activity were studied in the rat spinal cord using electrophysiological testing methods. Cell suspensions of cultured neonatal adrenal medullary chromaffin (AM) cells (which produce catecholamines), or Schwann (Sc) cells (controls) were implanted into the lumbar region of the spinal cord 2 weeks after catecholamine (CA) denervation by intracisternal injection of 6-hydroxydopamine (6-OHDA). All cells were taken from 7 day neonates and cultured for 10 days in the presence of nerve growth factor (NGF). Three months after implantation, the extent of implant-associated recovery of reflex activity was determined by measuring electromyogram (EMG) activity and force associated with the long latency component of the hindlimb withdrawal reflex (which is CA modulated). After the electrophysiological testing, rats were anesthetized, and the spinal cords were rapidly removed and frozen. Spinal cords were sectioned longitudinally, and implanted cells were visualized using glyoxylic acid techniques. Labelled sections were examined to determine cell survival. Results indicate that 1) chromaffin cells survive for 3 months in the segments of the cord into which they have been implanted and 2) rats implanted with AM cells have significantly more forceful withdrawal reflexes than those that received Sc cells or received no implant after lesioning. PMID:7703294

  14. Tensions in Creating Possibilities for Youth Voice in School Choice: An Ethnographer's Reflexive Story of Research

    ERIC Educational Resources Information Center

    Cotnam-Kappel, Megan

    2014-01-01

    The following article relates a reflexive ethnographic research project that focuses on youth voice in relation to the process of choosing a high school and a language of instruction in Ontario, Canada. The purpose of this methodological article is to relate a story of research and explore the tensions between theory and practice experienced by a…

  15. Myotatic reflexes and the on-off effect in patients with Parkinson's disease

    Microsoft Academic Search

    J R Dufresne; J F Soechting; E S Tolosa

    1981-01-01

    Reflex activity in the biceps and triceps muscles evoked by applied torque perturbations was studied in patients with Parkinson's disease. The perturbations consisted of single pulses or of pseudo-random sequences of pulses of torque. The patients were treated with levodopa and some exhibited marked fluctuations in their clinical disabilities (\\

  16. Autonomic dysfunction in muscular dystrophy: a theoretical framework for muscle reflex involvement

    PubMed Central

    Smith, Scott A.; Downey, Ryan M.; Williamson, Jon W.; Mizuno, Masaki

    2014-01-01

    Muscular dystrophies are a heterogeneous group of genetically inherited disorders whose most prominent clinical feature is progressive degeneration of skeletal muscle. In several forms of the disease, the function of cardiac muscle is likewise affected. The primary defect in this group of diseases is caused by mutations in myocyte proteins important to cellular structure and/or performance. That being stated, a growing body of evidence suggests that the development of autonomic dysfunction may secondarily contribute to the generation of skeletal and cardio-myopathy in muscular dystrophy. Indeed, abnormalities in the regulation of both sympathetic and parasympathetic nerve activity have been reported in a number of muscular dystrophy variants. However, the mechanisms mediating this autonomic dysfunction remain relatively unknown. An autonomic reflex originating in skeletal muscle, the exercise pressor reflex, is known to contribute significantly to the control of sympathetic and parasympathetic activity when stimulated. Given the skeletal myopathy that develops with muscular dystrophy, it is logical to suggest that the function of this reflex might also be abnormal with the pathogenesis of disease. As such, it may contribute to or exacerbate the autonomic dysfunction that manifests. This possibility along with a basic description of exercise pressor reflex function in health and disease are reviewed. A better understanding of the mechanisms that possibly underlie autonomic dysfunction in muscular dystrophy may not only facilitate further research but could also lead to the identification of new therapeutic targets for the treatment of muscular dystrophy. PMID:24600397

  17. Emphatic or Reflexive? On the Endophoric Character of French "lui-meme" and Similar Complex Pronouns.

    ERIC Educational Resources Information Center

    Zribi-Hertz, Anne

    1995-01-01

    This study examined the referential properties of a class of complex pronouns labelled M-Pronouns, exemplified by Old English "himself," French "lui-meme," and English "his own." It is shown that M-Pronouns exhibit some properties commonly taken as characterizing reflexive anaphors, and that they also occur as "intensive" pronouns. Contains 66…

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

    ERIC Educational Resources Information Center

    Lisle, Angela

    2006-01-01

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

  19. Seasonal variations of cough reflex sensitivity in elite athletes training in cold air environment

    PubMed Central

    2012-01-01

    Background Exercise-induced cough is common among athletes. Athletes training in cold air often report an increasingly troublesome cough during the winter season. Chronic airway irritation or inflammation may increase the sensory response of cough receptors. The aim of this study was to evaluate the seasonal variability of cough reflex sensitivity to capsaicin in elite athletes. Methods Fifty-three elite winter athletes and 33 sedentary subjects completed a respiratory questionnaire and a capsaicin provocation test during the summer, fall, and winter. Allergy skin prick tests, spirometry, eucapnic voluntary hyperpnea test (EVH), methacholine inhalation test (MIT), and induced sputum analysis were also performed. Results In athletes, the prevalence of cough immediately after exercise was high, particularly during winter. Athletes often showed a late occurrence of cough between 2-8 h after exercise. The cough reflex sensitivity to capsaicin was unchanged through the seasons in both athletes and non-athlete subjects. No significant correlations were found in groups between cough reflex sensitivity to capsaicin and the number of years in sport training, the number of hours of training per week, EVH response (% fall in FEV1), airway responsiveness to methacholine (PC20), airway inflammation or atopy. Conclusion The prevalence of cough immediately and a few hours after exercise is high in athletes and more frequently reported during winter. However, cough does not seem to be associated with cough reflex hypersensitivity to capsaicin, bronchoconstriction, or airway inflammation in the majority of athletes. PMID:22449054

  20. Aspects of the central integration of arterial baroreceptor and cardiac ventricular receptor reflexes in the cat.

    PubMed

    Little, R; Wennergren, G; Oberg, B

    1975-01-01

    The possible central integrative mechanisms, responsible for the earlier reported, differentiated reflex engagement of the renal and muscle vessels and the heart from cardiac ventricular receptors and arterial baroreceptors, respectively, were analyzed in atropinized cats. The reflux renal vessel, muscle vessel and heart rate responses, expressed as per cent of maximum, to graded activations of arterial baroreceptors (sinus pressure variations) and stimulations of ventricular receptor afferents in the cardiac nerve were systematically compared. Cardiac nerve stimulation with low frequencies was found to elicit more pronounced reflex renal vessel responses than muscle vessel and heart rate responses. In contrast, elevations of sinus pressure induced equally pronounced renal and muscle vessel responses. High frequency cardiac nerve stimulation elicited maximal reflex renal vessel responses, but only submaximal effects on muscle vessels and heart rate, while intense baroreceptor stimulation induced maximal reflex effector responses throughout. The submaximal heart rate response to cardiac nerve stimulation is probably due to a simultaneous activation of excitatory afferents. On the other hand, the less pronounced muscle than renal vessel responses when the cardiac nerve was stimulated probably reflect a relatively sparse innervation of muscle vasomotor neurons by ventricular receptor afferents, which seem instead to be preferentially oriented towards renal vasomotor and, possibly, cardiac motor neurons. PMID:1155134

  1. A reflexive approach to dealing with uncertainties in environmental health risk science and policy

    Microsoft Academic Search

    Matthieu Craye; Silvio Funtowicz; Jeroen P. Van Der Sluijs

    2005-01-01

    Based on insights obtained through an analysis of an environmental health risk controversy, we developed a reflexive approach to uncertainty assessment, explicitly acknowledging the complexity of the knowledge production process. The approach aims at interactively exploring uncertainty in relation to different scientific framings, societal perspectives and policy options. The structure of the discussion scheme used for the exploration is based

  2. Excitability of the soleus H-reflex arc during walking and stepping in man

    Microsoft Academic Search

    P. Crenna; C. Frigo

    1987-01-01

    In eight normal subjects, the excitability of the soleus (Sol) H-reflex was tested in parallel with Sol length changes, EMGs of leg and thigh muscles and ground contact phases, during three different pacing movements: bipedal treadmill walking, single limb treadmill walking, and single-limb stepping on one spot. A computerized procedure was used which compensated for changes in stimulus effectiveness that

  3. Hyperbaric hyperreflexia: tendon-jerk and Hoffmann reflexes in man at 43 bars.

    PubMed

    Harris, D J

    1979-12-01

    Tendon jerk (TJR) and Hoffmann (H) reflexes of the soleus muscle were studied in two men during a 26-day simulated oxygenhelium dive to a maximum pressure of 43 bars. The amplitude of the TJR response was observed to increase markedly after compression and also at the end of decompression. This biphasic pattern of enhanced reflectivity was reproduced by synchronised but much smaller variations in H reflex response. The positive facilitatory effects of applying Jenkdrassik's manoeuvre were reduced and the negative effects increased during hyperbaric exposure. Excitability cycles (twin-pulses methods) revealed modifications in one subject similar to those observed in clinical hyperreflexia, namely a shortening of Phase III and an enhancement of Phase IV. The other subject exhibited a notable depression of Phase IV. Abnormal EMG recordings are described including randomly-triggered slow wave potentials with no mechanical effects, and fixed, long latency late responses of a reflex nature with a definite mechanical effect. The contention that alterations in vestibulo-spinal relations may result in the release from tonic presynaptic inhibitory control of myotatic reflex arc excitability is discussed as a partial explanation for these and related findings. PMID:91497

  4. An artificial myotatic reflex: a potential avenue to fine motor control.

    PubMed

    Grundfest-Broniatowski, S; Broniatowski, M; Davies, C R; Jacobs, G B; Kasick, J C; Chou, S S; Nosé, Y; Hermann, R E; Tucker, H M

    1989-12-01

    When a striated muscle becomes paralyzed, not only its motor function, but its sensory innervation may be impaired. Methods of rehabilitation have previously focused only on motor innervation, although striated muscles are submitted to self-regulation of length and tension. Indeed, reinnervated muscle may not contract appropriately unless sensory information is available, nor is it known whether sensory receptors are included in the reinnervation process. We hypothesized that the myotatic reflex (MR) would be absent in the event these sensory organs are not reinnervated, and that an artificial myotatic reflex (AMR) would be useful in reestablishing fine motor control. The strap muscles were exposed in six anesthetized rabbits. The MR was verified by stretching an intact sternohyoid muscle. Next, loss of the reflex was documented after the ipsilateral ansa hypoglossi was divided, and a crossover nerve-muscle pedicle (NMP) was brought in from the opposite sternothyroid. After 3 months, the MR was still absent; however, stretch of the contralateral sternohyoid produced a reflex response on the reinnervated side. A strain gauge sutured to the reinnervated muscle was linked to an electronic modulator so that stretch induced electric stimulation of the NMP and contraction (the AMR). We conclude that (1) proprioception is not reestablished in the reinnervated muscle; (2) by contrast, sensory information from the muscle of origin of the NMP is conveyed to the reinnervated side; and (3) the AMR offers promise toward more sophisticated control of paralyzed (i.e., facial, laryngeal) musculature. PMID:2512549

  5. Effect of clorazepate in spasticity and rigidity: a quantitative study of reflexes and plasma concentrations.

    PubMed

    Lossius, R; Dietrichson, P; Lunde, P K

    1985-03-01

    The effect on increased myotatic reflexes of desmethyldiazepam, formed from its precursor clorazepate, was assessed in a double-blind cross-over study of 27 days duration. Eight patients with spasticity or rigidity were given placebo or active substance; first in loading doses for 2 days, then 5 mg every 12 h for a total of 10 days. A wash-out period of 7 days was interposed between the 2 10-day periods. Desmethyldiazepam had a normalizing effect on the increased phasic ankle reflexes seen in spasticity, but not on the increased tonic reflex seen in rigidity. The mean concentration of desmethyldiazepam in the steady state was 1227 nmol/l (range 600-1990 nmol/l). The plasma concentration of desmethyldiazepam tended to correlate with the percent decrease in phasic reflex activity (P = 0.08, 2-tailed). A slight drowsiness in 2 patients was the only side-effect seen. In conclusion, desmethyldiazepam given as clorazepate seems to be a suitable medicament in the treatment of spasticity. PMID:2859728

  6. Abnormal postural reflex activity and voice usage deviations in cerebral palsy.

    PubMed

    Keesee, P D

    1976-12-01

    A relationship is considered between abnormal postural reflex activity and its effect on vocal processes in infants and very young children having cerebral palsy. Neurodevelopmental treatment concepts are interpreted as they may apply to evaluation and intiial management of hypertonic children who exhibit voice usage deviations. Interdisciplinary team function in the areas of physical therapy, occupational therapy, and speech pathology is suggested. PMID:996091

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

    ERIC Educational Resources Information Center

    Spyrou, Spyros

    2011-01-01

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

  8. Reflexivity and Professional Use of Self in Research: A Doctoral Student's Journey

    ERIC Educational Resources Information Center

    Valandra, V.

    2012-01-01

    In this analysis I reflected how research reflexivity and professional use of self assisted me in completing my phenomenological doctoral study about African American mothers' experiences of sexual mistreatment and how those experiences influence their child rearing practices within an extended family system. I combined research and social work…

  9. Atypical Pupillary Light Reflex and Heart Rate Variability in Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Daluwatte, Chathuri; Miles, Judith H.; Christ, Shawn E.; Beversdorf, David Q.; Takahashi, T. Nicole; Yao, Gang

    2013-01-01

    We investigated pupillary light reflex (PLR) in 152 children with ASD, 116 typically developing (TD) children, and 36 children with non-ASD neurodevelopmental disorders (NDDs). Heart rate variability (HRV) was measured simultaneously to study potential impairments in the autonomic nervous system (ANS) associated with ASD. The results showed that…

  10. Debriefing Interviews and Coaching Conversations: Strategies to Promote Student Reflexivity and Action

    ERIC Educational Resources Information Center

    Maritz, J.; Jooste, K.

    2011-01-01

    Without conscious will and engagement in critical reflexivity as a process of growth and learning in research, students remain unaware of their subjective biases and the effect of bias on the inquiry. A qualitative, exploratory, single descriptive case study was used to explore and describe the operationalisation of debriefing interviews and…

  11. Motor and reflex testing in G M1-gangliosidosis model mice

    Microsoft Academic Search

    Satoshi Ichinomiya; Hiroshi Watanabe; Kimiko Maruyama; Hiroko Toda; Hiroyuki Iwasaki; Mieko Kurosawa; Junichiro Matsuda; Yoshiyuki Suzuki

    2007-01-01

    A large number of genetic disease model mice have been produced by genetic engineering. However, phenotypic analysis is not sufficient, particularly for brain dysfunction in neurogenetic diseases. We tried to develop a new assessment system mainly for motor and reflex functions in GM1-gangliosidosis model mice. Two genetically engineered model mouse strains were used for this study: the ?-galactosidase-deficient knockout mouse

  12. Ironic effects as reflexive responses: Evidence from word frequency effects on involuntary subvocalizations.

    PubMed

    Bhangal, Sabrina; Merrick, Christina; Morsella, Ezequiel

    2015-07-01

    In ironic processing, one is more likely to think about something (e.g., white bears) when instructed to not think about that thing. To further investigate this phenomenon involving cognitive control, in the Reflexive Imagery Task (RIT), participants are instructed to not subvocalize the names of visual objects. On the majority of the trials, participants fail to suppress such subvocalizations. This finding supports theorizing that conscious thoughts can be triggered by external stimuli in a manner that is nontrivial, involuntary, and, importantly, reflex-like. These conclusions challenge intuitions that consciousness is unpredictable, whimsical, and somewhat insulated from external control. Perhaps these thoughts arise, not in a reflex-like manner, but from experimental demand or other high-level, strategic processes. This prevalent criticism would be inconsistent with the observation that the RIT effect is influenced by a stimulus parameter such as word frequency. Regarding demand characteristics, such an artifact would require participants to have a theory regarding how word frequency should influence responses. We introduce evidence that stimuli associated with high frequency names are more likely to yield involuntary subvocalizations than stimuli associated with low frequency names. These theoretically-relevant data suggest that ironic effects in paradigms such as the RIT resemble reflex-like processes. PMID:26005914

  13. The Role of Habitus and Reflexivity in Young People Managing Pathways out of Crime

    ERIC Educational Resources Information Center

    France, Alan; Bottrell, Dorothy; Haddon, Edward

    2013-01-01

    This article draws on material from the ESRC funded "Pathways into and out of crime" research programme (Grant number L330253001) to explore how a group of educationally disaffected young people negotiate and try to manage their desistance from offending. We argue that the ability to be reflexive represents a form of embodied cultural…

  14. Breathtaking TRP Channels: TRPA1 and TRPV1 in Airway Chemosensation and Reflex Control

    Microsoft Academic Search

    Bret F. Bessac; Sven-Eric Jordt

    2008-01-01

    The airways are highly sensitive to damage by airborne reactive chemicals, toxic particulates, and infectious agents. Airway reflex responses such as cough and sneezing are crucial for the protection of the airways from chemical and biological challenges (33). Cough and sneezing are triggered by activation of peripheral sensory nerve endings in the airway lining. The air- ways are innervated by

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

    ERIC Educational Resources Information Center

    Urcuioli, Peter J.; Swisher, Melissa

    2012-01-01

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

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

    ERIC Educational Resources Information Center

    Urcuioli, Peter J.

    2011-01-01

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

  17. Approaching game-studies: towards a reflexive methodology of games as situated cultures

    Microsoft Academic Search

    Sybille Lammes

    2007-01-01

    This paper will address why and how a reflexive and situated methodology could be employed to study cultural functions of play. Starting from the supposition that playing is pivotal to all game-research, I will follow Aarseth's claim that any (cultural) approach of games asks for an inclusion of the position of the player\\/researcher in its methodology (1). Being particularly interested

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

    PubMed Central

    Kheradmand, A.; Zee, D.S.

    2014-01-01

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

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

    ERIC Educational Resources Information Center

    Harrison, Nigel; Kirkham, Janet

    2014-01-01

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

  20. The effects of multiple reflex pathways on the oscillations in neuro-muscular systems

    Microsoft Academic Search

    M. N. O?uztöreli; R. B. Stein

    1976-01-01

    A model of mammalian neuro-muscular systems described previously (Oguztöreli and Stein, 1975) has been extended to include multiple reflex pathways, as have been shown to exist in primates, including man (Milner-Brown et al., 1975). A number of general mathematical properties of the extended system are described. In the final section, using computer solutions, it is shown that the presence of

  1. Gain and threshold of the jaw-jerk reflex in man during isometric contraction

    Microsoft Academic Search

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

    1993-01-01

    The control of mandibular posture has been related to the activity of the anterior temporal muscles, whereas the masseter muscles have been viewed mainly as force producers. However, these groups of muscles, especially in the deep layers, are highly endowed with muscle spindles, so that a difference in function should imply a difference in the reflex sensitivity. By studying the

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

    E-print Network

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

  3. Engaging with Issues of Cultural Diversity and Discrimination through Critical Emotional Reflexivity in Online Learning

    ERIC Educational Resources Information Center

    Zembylas, Michalinos

    2008-01-01

    The purposes of this article are to describe the adult learners' emotional experiences as a result of engaging with issues of cultural diversity and discrimination, and to interrogate the ways in which critical emotional reflexivity emerges in the online format. The analysis is done in the context of an online course on diversity, inequality, and…

  4. Rethinking Attentional Development: Reflexive and Volitional Orienting in Children and Adults

    ERIC Educational Resources Information Center

    Ristic, Jelena; Kingstone, Alan

    2009-01-01

    It is thought that a child takes the first 8 years of life to develop an adult-like volitional attention system. The data that support this belief, however, are based on studies that inadvertently measured a combination of volitional and reflexive attention, rather than volitional attention alone. What is immature then in children that are younger…

  5. Assessing information of soleous and gastrocnemius motor unit H-reflex response to paired stimulation.

    PubMed

    Sarmadi, Alireza; Firoozabadi, Seyyed Mohammad; Torkaman, Giti; Fathollahi, Yaghoub

    2004-01-01

    In this study we compared soleous and gastrocnemius muscles responses to paired stimulation in order to reveal the embedded information in H-reflex of these muscles. Four men with ages between 20 and 26 were tested. Since there was no ideal point based on the scientific rules to record H-reflex from gastrocnemius muscle, we were to determine an ideal point and electrode placement from anatomical and physiological point of view. Then, soleous and gastrocnemius muscles were subjected to paired stimulus and H-reflex recovery curve of these muscles were recorded To record the recovery curve, 11 pairs of stimulus were delivered to the posterior tibial nerve. Time interval between the 1st pair of stimulus was 50 ms and increased by 20 ms steps in the next pairs up to 250 ms. The second H-reflex amplitude was divided to the first H-reflex amplitude and expressed in percent, then the recovery curve was drawn accordingly. While the time interval of the paired stimulus was less than 110 ms, the behavior of the curves was similar. In this stage we guessed that the muscles were impressed by the renshaw cells inhibition and the induced fatigue by the first stimulus. When the interval in a pair was 110 ms or more, the recovery percent of soleous was significantly higher than that of the gastrocnemius. This behavior may be due to the less fatigability of soleous motoneurons and less renshaw inhibition on slow motoneurons of soleous. When the time interval of a pair stimulus increases to more than 170 ms, both of the curves behave alike. This may be due to the diminishing of renshaw cell inhibition and the reduction of fatigue. Because of motoneurons physiological properties, when we evoke H-reflex, smaller motoneurons recruit predominantly; but the comparison of the soleous (slow) and gastrocnemius (fast) recovery curves behavior shows that the information about the fast motoneuron are included in H-reflex using this procedure. So we can indirectly assess different motoneurons and renshaw cell activities. PMID:15559074

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

    PubMed

    Stanhewicz, Anna E; Alexander, Lacy M; Kenney, W Larry

    2013-10-01

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

  7. Excitability of lower limb myotatic reflex arcs under the influence of caloric labyrinthine stimulation. Analysis of the postural effects in man.

    PubMed

    Delwaide, P J

    1977-10-01

    The excitability changes of myotatic reflex arcs have been investigated in 36 volunteers by two methods (tendon reflex and tonic vibration reflex) in a bilateral invertigation of soleus, quadriceps, biceps femoris, and tibialis anterior after caloric stimulation of the labyrinth. The extensor myotatic reflexes are facilated during the irrigation and the nystagmus phases. Contrary to the soleus, quadriceps facilitation is not symmetrical during the phase of nystagmus but predominates on the side opposite to the expected axial deviation. The short biceps femoris reflexes are slightly facilitated. The postural modifications arise from differences in the degree of bilateral facilitation of the extensors. PMID:591975

  8. Anodal vestibular stimulation does not suppress vestibular reflexes in human subjects.

    PubMed

    Bacsi, Ann M; Colebatch, James G

    2003-06-01

    Anodal current applied to the vestibular apparatus has previously been found to inhibit discharge from irregular vestibular afferents in squirrel monkeys. We wished to investigate whether anodal currents applied over the mastoid processes of human subjects would significantly reduce ongoing vestibular activity and thereby the size of galvanic-evoked vestibulospinal reflexes, measured by soleus electromyogram. Nine subjects were tested, of whom six subjects (five females, one male) provided data for the final analysis. Tonic anodal current was applied over one mastoid at 0 (baseline), 2, 4, 6 and 8 mA. The cathode was placed at C7. Superimposed on each intensity of tonic current were separate, short anodal currents of 4 mA, duration 20 ms, presented as 128 stimuli to the same side, and used to test vestibular responsiveness. These trials were then repeated with the anode overlying the contralateral mastoid. Short latency (SL) and medium latency (ML) reflexes were measured from the right soleus muscle. All six subjects used in the final analysis had readily identifiable reflexes to all stimuli. One-way ANOVA revealed no significant difference in the magnitude of the SL ( P=0.99) or ML ( P=0.96) components of the vestibulospinal reflexes across the group. Despite surface anodal currents of up to 8 mA, there was no consistent effect on the size of galvanic-evoked vestibulospinal reflexes. As 8 mA is close to the maximum intensity tolerated by volunteer subjects, our results indicate that anodal current applied over the mastoids is unlikely to be a useful means of suppressing vestibular function in human subjects. PMID:12739094

  9. Effect of angiotensin II on baroreceptor reflex control of heart rate in conscious baboons.

    PubMed

    Garner, M G; Phippard, A F; Fletcher, P J; Maclean, J M; Duggin, G G; Horvath, J S; Tiller, D J

    1987-12-01

    Studies of the baroreceptor-heart rate reflex were performed in four conscious, unrestrained male baboons to determine whether changes in circulating angiotensin II within the physiological range are associated with alterations in baroreceptor reflex sensitivity. With the animals on a high sodium intake, studies were performed before and during graded angiotensin II infusion (10 and 20 ng/kg/min). To separate effects on baroreceptor reflex function mediated by angiotensin II-induced increases in arterial pressure, these studies were repeated on a different day with simultaneous glyceryl trinitrate infusion to prevent increases in pressure during angiotensin II infusion. With the animals on a low sodium intake, studies were performed before and after angiotensin converting enzyme inhibition with captopril (1 and 5 mg/kg). These studies were also repeated on a separate day during simultaneous phenylephrine infusion to prevent a decrease in pressure with captopril. Reduction in sodium intake had no significant effect on arterial pressure, heart rate, or plasma volume, although arterial plasma angiotensin II concentration and renin activity were significantly increased (p less than 0.01). Infusion of angiotensin II produced a significant reduction in baroreceptor reflex sensitivity (p less than 0.01), and converting enzyme inhibition produced a significant increase (p less than 0.05). These effects accompanied significant increases and decreases in arterial angiotensin II concentration, respectively (p less than 0.01), but were independent of angiotensin II-related changes in arterial pressure. The data indicate that physiological variations in circulating angiotensin II have a direct effect on sensitivity of the baroreceptor-heart rate reflex. PMID:3121505

  10. The ipsilateral motor cortex does not contribute to long-latency stretch reflex amplitude at the wrist

    PubMed Central

    Fox, Jonathan; Shemmell, Jonathan

    2014-01-01

    Background A capacity for modulating the amplitude of the long-latency stretch reflex (LLSR) allows us to successfully interact with a physical world with a wide range of different mechanical properties. It has recently been demonstrated that stretch reflex modulation is impaired in both arms following monohemispheric stroke, suggesting that reflex regulation may involve structures on both sides of the motor system. Methods We examined the involvement of both primary motor cortices in healthy reflex regulation by eliciting stretch reflexes during periods of suppression of the motor cortices contra-and ipsilateral to the extensor carpi radialis in the nondominant arm. Results LLSRs were significantly attenuated during suppression of the contralateral, but not ipsilateral, motor cortex. Modulation of the LLSR was not affected by suppression of either primary motor cortex. Conclusion Our results confirm the involvement of the contralateral motor cortex in the transmission of the LLSR, but suggest that the ipsilateral motor cortex plays no role in reflex transmission and that neither motor cortex is involved in stability-dependent modulation of the LLSR. The implications of these results for reflex impairments following stroke are discussed. PMID:24653955

  11. Phase-dependent and task-dependent modulation of stretch reflexes during rhythmical hand tasks in humans

    PubMed Central

    Xia, Ruiping; Bush, Brian M H; Karst, Gregory M

    2005-01-01

    Phase-dependent and task-dependent modulation of reflexes has been extensively demonstrated in leg muscles during locomotory activity. In contrast, the modulation of reflex responses of hand muscles during rhythmic movement is poorly documented. The objective of this study was to determine whether comparable reflex modulation occurs in muscles controlling finger motions during rhythmic, fine-motor tasks akin to handwriting. Twelve healthy subjects performed two rhythmic tasks while reflexes were evoked by mechanical perturbations applied at various phases of each task. Electromyograms (EMGs) were recorded from four hand muscles, and reflexes were averaged during each task relative to the movement phase. Stretch reflexes in all four muscles were found to be modulated in amplitude with respect to the phase of the rhythmic tasks, and also to vary distinctly with the tasks being conducted. The extent and pattern of reflex modulation differed between muscles in the same task, and between tasks for the same muscle. Muscles with a primary role in each task showed a higher correlation between reflex response and background EMG than other muscles. The results suggest that the modulation patterns observed may reflect optimal strategies of central–peripheral interactions in controlling the performance of fine-motor tasks. As with comparable studies on locomotion, the phase-dependency of the stretch reflexes implies a dynamically fluctuating role of proprioceptive feedback in the control of the hand muscles. The clear task-dependency is also consistent with a dynamic interaction of sensory feedback and central programming, presumably adapted to facilitate the successful performance of the different fine-motor tasks. PMID:15746170

  12. Pupillary light reflex deficits in a canine model of late infantile neuronal ceroid lipofuscinosis.

    PubMed

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

    2013-11-01

    Late-infantile neuronal ceroid lipofuscinosis (CLN2) is a hereditary neurological disorder characterized by progressive retinal degeneration and vision loss, cognitive and motor decline, seizures, and pronounced brain atrophy. The progressive loss of neurological functions eventually leads to death, usually by the early teenage years. Utilizing a canine model of CLN2, therapeutic studies to inhibit the brain and retinal degenerations are currently under way. Using this dog model, studies were undertaken to compare quantitative assessments of the pupillary light reflex (PLR) and electroretinography (ERG) as tools for evaluating the effects of the disease on retinal function. The PLR and ERG were recorded in normal and CLN2-affected Dachshunds at 2 month intervals between the ages of 4 and 10 months. Using custom instrumentation for quantitative PLR assessments, a series of white light stimuli of varying intensity was used to elicit pupil constriction, and pupil images were recorded using continuous infrared illumination and an infrared-sensitive camera. Electroretinography was used to evaluate retinal function in the same dogs. As the disease progressed, affected dogs exhibited progressive and profound declines in ERG amplitudes under both scotopic and photopic conditions. With low intensity light stimuli, CLN2 was also accompanied by progressive deficits in the PLR. Changes in the PLR to dim light stimuli included significant deficits in latency, constriction velocity, constriction amplitude, and redilation velocity. However, despite the almost complete loss of detectable ERG responses by disease end stage, the PLR to bright stimuli was well preserved throughout the disease progression. These findings demonstrate that the PLR is much more sensitive than the ERG in detecting residual retinal function in animal models of retinal degenerative disease. The preservation of the PLR in dogs with profoundly depressed ERGs correlates with a preservation of visually-mediated behavior even late in the disease progression. Quantitative analysis of the PLR has potential as a biomarker in animal models of retinal degenerative diseases and in evaluating the efficacy of therapeutic interventions in preserving retinal function. PMID:24135299

  13. Glutamatergic receptor dysfunction in spinal cord contributes to the exaggerated exercise pressor reflex in heart failure.

    PubMed

    Wang, Han-Jun; Cahoon, Rebecca; Cahoon, Edgar B; Zheng, Hong; Patel, Kaushik P; Zucker, Irving H

    2015-03-01

    Excitatory amino acids (e.g., glutamate) released by contraction-activated skeletal muscle afferents into the dorsal horn of the spinal cord initiate the central component of the exercise pressor reflex (EPR) in physiological conditions. However, the role of glutamate and glutamate receptors in mediating the exaggerated EPR in the chronic heart failure (CHF) state remains to be determined. In the present study, we performed microinjection of glutamate receptor antagonists into ipisilateral L4/L5 dorsal horns to investigate their effects on the pressor response to static contraction induced by stimulation of the peripheral end of L4/L5 ventral roots in decerebrate sham-operated (sham) and CHF rats. Microinjection of glutamate (10 mM, 100 nl) into the L4 or L5 dorsal horn caused a greater pressor response in CHF rats compared with sham rats. Furthermore, microinjection of either the broad-spectrum glutamate receptor antagonist kynurenate (10 mM, 100 nl) or the N-methyl-d-aspartate (NMDA) receptor antagonist dl-2-amino-5-phosphonovalerate (50 mM, 100 nl) or the non-NMDA-sensitive receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (5 mM, 100 nl) into L4/5 dorsal horns decreased the pressor response to static contraction in CHF rats to a greater extent than in sham rats. Molecular evidence showed that the protein expression of glutamate receptors (both non-NMDA and NMDA) was elevated in the dorsal horn of the lumbar spinal cord in CHF rats. In addition, data from microdialysis experiments demonstrated that although basal glutamate release at the dorsal horn at rest was similar between sham and CHF rats (225 ± 50 vs. 260 ± 63 nM in sham vs. CHF rats, n = 4, P > 0.05), CHF rats exhibit greater glutamate release into the dorsal horn during muscle contraction compared with sham rats (549 ± 60 vs. 980 ± 65 nM in sham vs. CHF rats, n = 4, P < 0.01). These data indicate that the spinal glutamate system contributes to the exaggerated EPR in the CHF state. PMID:25502111

  14. For a social ontology with a self-reflective knowing subject: towards the articulation of the epistemic criterion of reflexivity 

    E-print Network

    Bouzanis, Christoforos

    2013-07-02

    This thesis argues for the idea that there are deep interconnections between the notions of ontology and reflexivity. It starts from the idea that ontological claims are cognitionally prior to epistemological and ...

  15. [Effect produced by the alkaloid fraction of Mimosa tenuiflora (tepescohuite) on the peristaltic reflex of the guinea pig ileum].

    PubMed

    Meckes-Lozoya, M; Lozoya, X; González, J L; Martínez, M

    1990-01-01

    An alkaloidal fraction was obtained from Mimosa tenuiflora (Willd.) Poir (tepescohuite) trunk bark. The product contained mainly an indolealkylamine and three minor alkaloids. This fraction inhibited the peristaltic reflex in the guinea-pig isolated ileum in vitro. PMID:2103706

  16. Central 5HT7 receptors are critical for reflex activation of cardiac vagal drive in anaesthetized rats

    Microsoft Academic Search

    Daniel O. Kellett; G. Ramage; David Jordan

    2004-01-01

    5-Hydroxytryptamine (5-HT; serotonin)-containing neurones contribute to reflex activation of parasympathetic outflow in a number of species, but the 5-HT receptors mediating these effects have yet to be fully determined. The present experiments demonstrate that central 5-HT7 receptors are involved in the vagal bradycardia evoked during the cardiopulmonary reflex, baroreflexes and the chemoreflex, as well as other autonomic changes caused by

  17. 3-Nitropropionic acid-induced depression of spinal reflexes involves mechanisms different from ischemia-induced depression

    Microsoft Academic Search

    Rajesh Gupta; Shripad B. Deshpande

    2008-01-01

    Effect of 3-nitropropionic acid (3-NPA) and ischemia (glucose- and O2-free solution) on synaptic transmission in hemisected spinal cord from 4 to 8 day old rats was examined in vitro. Stimulation of a dorsal root (L3-5 segments) evoked monosynaptic (MSR) and polysynaptic reflex (PSR) potentials in the segmental ventral root. Superfusion of 3-NPA (0.17–3.4mM) depressed the reflexes in a concentration- and

  18. Adjuvant physical therapy versus occupational therapy in patients with reflex sympathetic dystrophy\\/complex regional pain syndrome type I

    Microsoft Academic Search

    H. Margreet Oerlemans; Rob A. B. Oostendorp; Theo de Boo; Lyckle van der Laan; Johan L. Severens; R. Jan A. Goris

    2000-01-01

    Oerlemans HM, Oostendorp RAB, de Boo T, van der Laan L, Severens JL, Goris RJA. Adjuvant physical therapy versus occupational therapy in patients with reflex sympathetic dystrophy\\/complex regional pain syndrome type I. Arch Phys Med Rehabil 2000;81:49-56. Objective: To investigate the effectiveness and cost of physical therapy (PT) or occupational therapy (OT) in patients with reflex sympathetic dystrophy (RSD). Design:

  19. Comparison of spinal myotatic reflexes in human adults investigated with cross-correlation and signal averaging methods

    Microsoft Academic Search

    S. Miller; J. Clark; J. A. Eyre; S. Kelly; E. Lim; V. M. McClelland; S. Mc Donough; A. V. Metcalfe

    2001-01-01

    A cross-correlation method for recording spinal myotatic reflexes has been developed to meet the need for brief test periods in babies and children and subjects with central neurological pathology. In normal adult subjects the method has been validated by comparing excitatory and inhibitory reflexes obtained with cross-correlation with those obtained with conventional signal averaging. In the cross-correlation method a pseudo-random

  20. A review of the modulation of the startle reflex by affective states and its application in psychiatry

    Microsoft Academic Search

    Christian Grillon; Johanna Baas

    2003-01-01

    Objective: To provide an overview of startle reflex methodologies applied to the examination of emotional and motivational states in humans and to review the findings in different forms of psychopathology.Methods: Pertinent articles were searched mostly via MEDLINE and PsycINFO.Results: The startle reflex is a non-invasive translational tool of research that bridges the gap between animal and human investigations. Startle is