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At least 181 records · Page 10Linked to original sources

PubMed1983

Reinforcement of tonic vibration reflex and exteroceptive vibration-induced flexion reflex in finger flexion muscles by forced respiration.

The effects of forced respiration on tonic vibration reflex (TVR) and exteroceptive vibration-induced flexion reflex (VFR) were studied in healthy man. vibration (100 Hz) applied to finger flexion muscles or the volar side of the middle finger induced a slowly augmenting facilitation of the TVR, which has mono-and polysynaptic components, and VFR, which is polysynaptic. Forced inspiration and forced expiration facilitated these slowly augmenting processes in both reflexes. Respiration reinforces both proprioceptive and exteroceptive reflexes elicited by vibration.

Adult↗

PubMed1981

Basal and reflex human tear analysis. I. Physical measurements: osmolarity, basal volumes, and reflex flow rate.

Minimally stimulated, retained "basal' tears and stimulated reflex tears were collected from normal controls, keratoconjunctivitis sicca (KCS) patients, and contact lens (CL) wearers. Basal tear samples were collected on small filter paper strips (Periopaper) over a five-second period, and volume was measured by means of an electronic device (Periotron). Collected basal tear volumes for KCS patients (0.84 +/- 0.42 mul) were significantly lower (P less than 0.01) than normal controls (1.18 +/- 0.36) and CL wearers (1.24 +/- 0.27). Reflex tear flow rates were measured over a five-minute period on Schirmer strips. Volume was calculated by comparison of wet length with known volumes of 1% egg white lysozyme solution. The reflex tear flow rates in KCS patients (3.29 +/- 3.57 mul/minute) were significantly lower than normal controls (5.71 +/- 5.86) and CL wearers (6.96 +/- 6.07). The elevation in CL wearers was not statistically significant when compared to normals. KCS patients are deficient in both basal and reflex tears compared to normals but have a more significant deficiency of basal tears. Female normals and CL wearers over 40 years of age have a higher tear osmolarity than those under 41 years of age. Female KCS patients over 40 years of age have a tear osmolarity that is not significantly different from female KCS patients under 41 years of age.

Adult↗

PubMed1996

Vibration-induced finger flexion reflex and inhibitory effect of acupuncture on this reflex in cervical spinal cord injury patients.

The vibration-induced finger flexion reflex (VFR) and the inhibitory effect of acupuncture on this reflex were studied in five cervical spinal cord injury patients (C-SCIs). VFR, which is a tonic finger flexion reflex induced by vibratory stimulation on the finger tip, was induced before and after acupuncture was carried out on the same hand. A stainless steel needle was inserted to the Hoku point. As in healthy subjects, VFR was performed and it was significantly inhibited by acupuncture in the C-SCIs; mean maximum VFR was 204.2 +/- S.E. 68.6 g before and 119.8 +/- S.E. 42.2 g after acupuncture. The present results suggest that at least part of the reflex center for VFR is located in the spinal cord and that part of VFR inhibition by acupuncture may be mediated via the spinal cord.

Acupuncture Therapy↗

PubMedDate not supplied

Role of the cervico-ocular reflex in the "flying" pigeon: interactions with the optokinetic reflex.

We studied the cervico-ocular reflex (COR) alone and in combination with the optokinetic (OKN) reflex in head-fixed pigeons. We analyzed these responses in two behavioral conditions: (1) animals were hung in a harness ("resting" condition); and (2) animals were additionally submitted to a frontal airflow that provoked a flight posture ("flying" condition). In both conditions, cervical stimulation provoked a slow phase of very low gain (around 0.05) in the opposite direction to that of the stimulation and fast phases triggered near the head-body alignment in the same direction as the stimulation. The slow phase showed a phase lag of 20 deg at 0.5 Hz. The gain of the slow phase was not modified by the velocity, amplitude, or frequency of the stimuli. This gain was not changed by the presence of a fixed visual surround. When cervical stimuli (0.05-0.5 Hz) were added to an optokinetic stimulation (30 deg/s) in the "resting" condition, the slow phase velocity (SPV) of the optokinetic reflex was modulated with a time course close to that produced by the cervico-ocular reflex alone. The SPV was alternately increased and decreased round the SPV level corresponding to the steady-state OKN. In the "flying" condition, optokinetic-cervical stimulation provoked an eye beating field and a strong SPV modulation synchronized with the position of the cervical stimulation. The number of nystagmic beats (OKN) and the amplitude and velocity of the fast phases were modulated in correlation with the SPV. Consequently, the optokinetic response was increased or decreased according to whether the cervical stimuli were in the reverse direction or in the same direction as the optokinetic stimulation, respectively. These data are interpreted as an improvement of gaze stabilization by the COR. This mechanism is context dependent, since it is strongly reinforced during the flight.

Animals↗

PubMed1990

Effects of brainstem lesions on the masseter inhibitory reflex. Functional mechanisms of reflex pathways.

The masseter inhibitory reflex (MIR) was investigated in 16 patients with localized brainstem lesions involving the trigeminal system. The MIR consists of two phases of EMG silence (S1 and S2) evoked by stimulation of the mental nerve during maximal clenching of the teeth. The extent of the lesions was assessed by neurological examination, nuclear magnetic resonance imaging (MRI), and recording of trigeminal reflexes with known paths (jaw jerk and blink reflex). The MIR appeared to be abnormal in lesions involving the pontine tegmentum, from the pontomedullary junction to midpons, and some lesions selectively affected one component of the MIR, proving that S1 and S2 are relayed by independent circuits. The results indicate that afferent fibres for S1, which reach the pons via the trigeminal sensory root, enter the ipsilateral trigeminal spinal tract and terminate at the level of the midpons; impulses are then relayed by interneurons to the ipsilateral and contralateral trigeminal motor nuclei. The afferent fibres for S2 follow a similar path, but descend to the pontomedullary junction; at this level impulses are conducted along bilateral interneuronal paths, which probably ascend through the lateral reticular formation, before connecting with the trigeminal motor nucleus on either side. Analysis of MIR recordings can be of particular value because brainstem inhibitory reflexes cannot be tested by clinical examination.

Adult↗

PubMed2001

Trigeminocervical reflexes elicited by stimulation of the infraorbital nerve: head retraction reflex.

In the current study, the effects of stimulation of the infraorbital nerve (ION) on the trigeminocervical reflexes (TCRs), recorded from the posterior neck muscles, was investigated and the results were compared with the results recorded by stimulation of the supraorbital nerve (SON). TCRs obtained by stimulation of the ION was evaluated as the electrophysiologic counterpart of the head retraction reflex. Twenty normal control subjects, 10 men and 10 women, were enrolled in the study. The SON and the ION were stimulated by using a bipolar surface electrode. Results were recorded by using either concentric needle electrodes inserted into the semispinalis capitis muscle at the level of the third or fourth cervical vertebra or by surface electrodes placed at the C3 and C7 vertebrae on the midline. It was found that stimulation of the supraorbital and infraorbital branches of the trigeminal nerve had different reflexive effects on the posterior neck muscles. A stable positive (or negative-positive) wave, with a very early latency and high amplitude was always recorded after maximal stimulation of the ION, which could never be detected by stimulation of the SON. The C3 response of the TCR, evoked by SON stimulation was always evoked, by stimulation of the ION, at a low threshold. These findings suggest that the head retraction reflex is composed of two phases: inhibitory and excitatory. The early, fixed positive wave represents the general inhibition of the cranial and neck muscles, just before withdrawal of the face and head, from unexpected stimuli, which precedes the dense C3 response, demonstrating activation of the posterior neck muscles.

Adult↗

PubMed2001

The masseter reflex: postprocessing methods and influence of age and gender. Normative values of the masseter reflex.

OBJECTIVES: Normative values of the masseter reflex are scarce. We studied the latencies, amplitudes and side differences of the masseter reflex in 105 healthy volunteers between the ages of 5 and 78 years. METHODS: Latencies were calculated as the mean of 10 single sweeps and, simultaneously, measured from the summation curve. Short-term reproducibility was determined in 33 volunteers by retesting the reflex after 1 week. RESULTS: There was a positive correlation between age and latencies and a negative correlation between age and amplitude. Maximal normal latencies were 8.3 ms for men and 7.9 ms for women in the age group below 50 years and 9.1 and 9.2 ms for the age group above 50 years. Latency differences between the right and left sides of >0.4 ms for subjects aged below 50 years and >0.5 ms for subjects aged above 50 years exceeded the 95% confidence interval. Amplitudes did not depend on gender. Calculated as a percentage of the side with higher amplitude, differences above one third could be accepted as abnormal. CONCLUSION: The masseter reflex appears to be a stable and robust clinical test, if age and gender differences are taken into account.

Adolescent↗

PubMed1994

Uterocervical reflex: description of the reflex and its clinical significance.

The effect of uterine distension on the cervix was studied in 16 women (mean age 38.4 years). Carbon dioxide was infused, in increments up to 50 ml, into a condom-ended catheter introduced into the uterus. The response of uterine and cervical pressures to uterine distension was determined before and after anesthetizing the uterine body and the cervix, respectively. Upon slow uterine distension, the cervical pressure increased (p < 0.01), while the uterine pressure showed insignificant changes (p > 0.05). Rapid distension led to cervical pressure decrease (p < 0.01) and increase of uterine pressure (p < 0.01). The cervical pressure did not respond to slow or rapid inflation of the anesthetized uterus, neither did the anesthetized cervix respond to uterine inflation. A reflex relationship seems to exist between the uterine body when distended and the cervix, which we call 'uterocervical reflex'. The study demonstrates that the uterus behaves differently under physiologic and pathologic conditions. Upon slow uterine distension as in pregnancy, the uterus adapts by uterine dilatation and cervical tightening. In pathologic conditions which distend the uterus rapidly, the latter reacts with uterine contraction and cervical dilatation, discharging the uterine contents. Dysfunction of the uterocervical reflex may result in uterine and cervical disorders. The reflex may thus be included as a diagnostic tool in such disorders.

Adult↗

PubMed2001

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

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

Amphetamines↗

PubMed1979

Calibration of ipsilateral acoustic reflex stimuli. A comparison of loudness balance and equal reflex response methods.

Hearing levels for ipsilateral impedance probes have not yet been established. This study compares two techniques for "transfer of threshold" from the standardised TDH-39 earphone to the unstandardised probe. Ten normal hearing subjects participated, using both a loudness balance technique and a reflex measurement technique. The reflex measurement technique involved comparing the intensity required from each transducer to produce an equal reflex response, whereas the loudness balance technique compared the intensity required from each transducer for equal loudness. The two techniques were found to differ significantly in terms of the Hearing Level values which they produced. Differences between techniques amounted to approximately 3 dB at 1000 Hz, 11 dB at 2000 Hz, and 7 dB at 3000 Hz. As a comparison of the two techniques, the day to day variances were statistically estimated. The reflex measurement technique was shown to be more reliable than the loudness balance technique.

Acoustic Impedance Tests↗

PubMed1990

[Reflex control on laryngeal functions--vibration effect of the laryngeal mucosa on recurrent laryngeal nerve reflexes].

Electromyographic (EMG) responses of the intrinsic laryngeal muscle have been investigated to clarify reflexogenic laryngeal controls from a viewpoint of its functional significance during phonation. Twenty-five adult cats were anesthetized with intraperitoneal injection of 4ml/kg of a mixture of 10% urethane and 1% alpha-chloralose. Either the internal branch of the superior laryngeal nerve (ISLN) or the recurrent laryngeal nerve (RLN) was carefully dissected and central end of the dissected nerve was electrically stimulated. EMG of the contra-lateral Thyro-Arytenoid muscle (TA muscle) to the stimulation was recorded using a hooked-wire electrode inserted through the laryngeal mucosa. EMG of the TA muscle evoked by the stimulation of the ISLN were analyzed with respect to its latency and discharge pattern inter-collicular brainstem transsected. Together with the stimulation of the RLN, vibratory stimuli were given mainly to the subglottic mucosa as conditioning stimuli. The vibratory frequency was changed from 50Hz to 400Hz step-wisely. Following results were obtained. 1. EMG response of the contra-lateral TA muscle to the stimulation of the ISLN showed two different kinds of latency, approximately 8-10msec, and 40-60msec. 2. After inter-collicular brainstem transsection, evoked response of the latter disappeared. This result indicates that the ISLN-RLN reflex loop consisted of more than two routes, different in the number of synaptic junctions. 3. The vibratory stimuli given to the laryngeal mucosa had facilitatory effect on the reflexive EMG response evoked by the stimulation of the RLN. 4. This facilitatory effect of the vibratory stimuli disappeared after topical anesthesia of the laryngeal mucosa. 5. The facilitatory effect on the reflex responses was partially increased depending on the vibratory frequencies applied. In conclusion, vibratory stimuli to the laryngeal mucosa reflexively modulate the activity of the intrinsic laryngeal muscles.

Animals↗

PubMed2000

[Electromyographic study of the striated urethral sphincter by using the bulbocavernosus reflex: study on change of sacral reflex activity caused by bladder filling].

PURPOSE: The change of sacral reflex activity of the striated urethral sphincter in the urine storage phase is investigated using evoked potential reaction of the bulbocavernosus reflex (BCR). METHODS: Eleven normal male subjects and 13 male patients with neurogenic bladder due to suprasacral (C3-C7) spinal cord injury (SCI patients) were investigated. Within the SCI patients, five were complete SCI and 8 were incomplete SCI. BCR was elicited by electrical stimulation of dorsal nerve of the penis, and the evoked potential of the BCR was recorded with a concentric needle electrode from the periurethral striated muscle. BCR was performed both at empty and at filled bladder respectively, and changes of the amplitudes (AMP) were examined. Moreover, the changes of AMP affected by bladder filling were compared between the normal subjects and the SCI patients. RESULTS: In both the normal subjects and the SCI patients, AMP increased at the filled bladder as compared with that of the empty bladder. In addition, the change of AMP was statistically bigger in the SCI patients (a ratio of amplitude at filled bladder/amplitude at empty bladder: 4.73 +/- 3.90) than in the normal subjects (the ratio: 1.32 +/- 0.44). CONCLUSION: Sacral reflex activity was accelerated by bladder filling in both the normal subjects and SCI patients. And the acceleration in the SCI patients was more remarkable than that in the normal subjects. In addition to the conventional evaluation of the integrity of sacral reflex arc by BCR examination, the observation of changes of BCR affected by bladder filling may provide the information for the continuity of sacral segment and supraspinal micturition center.

Adult↗

PubMed1990

[The spinal monosynaptic reflexes elicited from the tibialis anterior muscle--standardization of the reflexes and diagnostic use in L5 radiculopathy].

The spinal monosynaptic reflexes evoked in the tibialis anterior muscle were investigated to establish a practical method for assessing L5 radiculopathy. Voluntary contraction and averaging technique made it possible to consistently obtain the H-and T-reflexes from the muscle in which these reflexes are normally unelicitable at rest. Based on the study of fifty normal subjects, formulae were produced by an analysis of the simultaneous regression of the latencies of these reflexes on height and age, because these latencies were highly correlated with them. A side-to-side latency difference of the H-and T-waves greater than 1.5 msec. and 2.3 msec. respectively, and/or low amplitude less than 26% and 39% of the amplitude of the contralateral side respectively, could be considered abnormal. According to these criteria, eight out of twelve patients (67%) with unilateral compressive L5 radiculopathy showed abnormalities.

Electrophysiology↗

PubMed1985

Effects of hypoxia on respiratory defence reflexes. Effects of thirty hours' oxygen deficiency on cough, the expiration reflex and sneezing in awake cats.

The authors studied, in 11 awake adult cats, the parameters of the expiration reflex (ER), tracheobronchial (TB) and laryngopharyngeal (LPh) cough, the respiratory rate (f), tidal volume (VT), the end tidal fractional CO2 concentration (FETCO2), the pH, the blood gases and the heart rate during 30 hours' isobaric hypoxic hypoxia (FO2 = 0.11). During the whole 30 hours the cats developed hypocapnic hypoxemia, f remained unchanged and VT was markedly elevated. In the acute phase (15 min) of hypoxic hypoxia of the same intensity, changes in respiratory parameters were the same and the intensity of respiratory reflexes increased significantly (Tatár et al. 1984). During prolonged hypoxic hypoxia there were no statistically significant changes in the intensity of the ER and of TB and LPh cough. The authors assume that some adaptation of the central mechanisms regulating the defence reflexes of the airways took place; this hypothesis is warranted, because an increase in the susceptibility of the cough centre during constant conditions of the stimulation of cough receptors would not be biologically expedient. The different changes in the intensity of respiratory defense reflexes in the acute and the prolonged phase of hypoxic hypoxia in the presence of identical changes in respiratory parameters are further indirect evidence pointing to the existence of functional differences between the respiratory centre and the cough centre.

Animals↗

PubMedDate not supplied

[Blink reflex and jaw reflex in neurinoma of the acoustic and trigeminal nerves (author's transl)].

The blink reflex was studied in four patients with neurinoma of the acoustic nerve and in two patients with trigeminal neurinoma. It was abnormal in all cases except in one neurinoma of the acoustic nerve inside the canal. The jaw reflex, studied in four cases, showed unilateral impairment in two cases of trigeminal neurinoma and one case of acoustic neurinoma; it was normal in the case of acoustic neurinoma in the canal. The blink reflex and jaw reflex merit inclusion among the further tests conducted in cases of suspected neurinoma of the trigeminal or acoustic nerves. However, they are of less interest than oto-vestibular tets in the early diagnosis of neurinoma of the eighth nerve. These techniques deserve a place of choice in investigations of atypical facial neuralgia in general and suspected neurinoma of the trigeminal in particular.

Adult↗

PubMed1977

Conditioning of H reflex by a preceding subthreshold tendon reflex stimulus.

The soleus H reflex excitability cycle has been studied using, as conditioning stimulus, a mechanical tap, subthreshold for the tendon reflex, which was applied either on the Achilles tendon, the short biceps tendon, or the quadriceps tendon. In all cases there was an early facilitation followed by a longlasting inhibition of the test H reflex. The same results were obtained in patients with a complete spinal cord section. Wherever the site of the conditioning stimulation, these modifications disappeared after ischaemia of the leg. It is concluded that the effects observed are due to the activation by the tendon tap of the Ia nerve fibres from the soleus muscle, and that the longlasting inhibition is probably due to a transmitter depletion.

Adult↗

PubMedDate not supplied

Heart rate deceleration is not an orienting reflex; heart rate acceleration is not a defensive reflex.

Graham and Clifton (1966) proposed an integration of Sokolov's theory of orienting and defensive reflexes with the stimulus intake/rejection dichotomy of the Laceys. This integration consisted of hypothesizing that heart rate deceleration is a measure of the orienting reflex, and that cardiac acceleration is a measure of the defensive reflex. This article demonstrates that Graham and Clifton failed to establish a valid integration of these two theories. This failure is a consequence of 1) their misconstruing Sokolov's theory, and 2) an inaccurate and selective review of the research literature then available. Consideration of more recent research would seem to rule out the possibility that their thesis was correct in spite of these flaws in its derivation. Cardiac responding in the OR context thus remains open to further investigation and interpretation.

Acoustic Stimulation↗

PubMed1991

Trigeminocardiac reflexes: maxillary and mandibular variants of the oculocardiac reflex.

Three case reports are presented to illustrate the existence and importance of reflex bradycardic responses that can occur during maxillofacial surgical procedures. All three patients were healthy young adults undergoing operations which did not include any manipulation of orbital structures. After the patients had been anaesthetized for some time and were haemodynamically stable, profound bradycardia or ventricular asystole occurred suddenly in response to manipulations of the bony structures of the maxilla or mandible, or dissection of, or traction on, the attached soft tissue structures. The parasympathetic supply to the face is carried in the trigeminal nerve. Alternative afferent pathways must exist via the maxillary and/or mandibular divisions, in addition to the commonly reported pathway via the ophthalmic division of the trigeminal nerve in the classic oculocardiac reflex. The efferent arc involves the vagus, regardless of which branch of the trigeminal nerve transmits the afferent impulses. All patients undergoing maxillofacial procedures should be monitored carefully for reflex bradycardia and ventricular asystole.

Adult↗