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At least 181 records · Page 10Linked to original sources
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↗
PubMed1990

Effects of a new analog of thyrotropin-releasing hormone, N alpha-[(S)-4-oxo-2-azetidinyl) carbonyl]-L-histidyl-L-prolinamide dehydrate (YM-14673) on spinal reflex potentials and flexor reflexes in spinalized rats.

Experiments were performed on spinalized rats, transected at the Cl level. The intravenous administration of TRH and its analog YM-14673 (N alpha-[(S)-4-oxo-2-azetidinyl) carbonyl]-L-histidyl-L-prolinamide dehydrate) produced marked increases in the amplitude of mono- and polysynaptic reflex potentials and those of the withdrawal flexor reflexes. The effects of YM-14673 were stronger and longer-lasting than those of TRH. The stimulant action of TRH and YM-14673 on the flexor reflexes was not antagonized by prazosin, chlorpromazine, haloperidol or cyproheptadine, suggesting no involvement of the release of catecholamines or serotonin in the stimulant effects of TRH and its analog. Therefore, YM-14673 may be beneficial for the treatment of several spinal motor neuron diseases.

Animals↗
PubMed2002

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

The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex- and age-matched controls were selected. In subgroups of migraine with-aura and without-aura patients, and normal controls, the blink reflex was elicited during different cognitive situations: (a) spontaneous mental activity; (b) stimulus anticipation; (c) recognition of target numbers. In the remaining subjects, R2 and R3 habituation was evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s intervals. The R2 and R3 recovery curves were also computed. A reduced R3 threshold with a normal pain threshold was found in migraine with-aura and without-aura patients; the R3 component was not significantly correlated with the pain thresholds in patients and controls. The R2 and R3 components were less influenced by the warning of the stimulus in migraine without-aura and migraine with-aura patients, in comparison with the control group. A slight increase of both R2 and R3 recovery after preconditioning stimulus was also observed in migraine patients, probably caused by a phenomenon of trigeminal hyperexcitability persisting after the last attack. The abnormal BR modulation by alerting expresses in migraine a dysfunction of adaptation capacity to environmental conditions, probably predisposing to migraine.

Adult↗
PubMed1979

Modulation of the acoustic startle reflex in humans in the absence of anticipatory changes in the middle ear reflex.

If a weak tone precedes an intense tone, then the acoustic startle eyeblink reflex elicited by the stronger stimulus is inhibited. It has been suggested that the leading stimulus gives rise to a protective middle ear reflex that attenuates the effective intensity of the second. This hypothesis was tested and disproved. In seven subjects intense tone bursts sufficient to elicit both intratympanic and eyeblink responses were presented sometimes alone and sometimes preceded at various lead times (25 to 400 msec) by a weak tone. The weak tone inhibited the amplitude of the eye blink to the strong tone, maximally at intervals of 100 to 200 msec, but was never seen to produce any of the anticipatory impedance changes that would be characteristic of middle ear reflex activity during the interval between the two stimuli.

Adolescent↗
PubMed1978

Reflex arc of the first component of the human blink reflex: a single motoneurone study.

Latency variation of consecutive responses of single orbicularis oculi motoneurones in the first component of the electrically elicited blink reflex was 2.6 times larger than that of the H reflex of the soleus muscle fibres. Some motoneurones showed bimodal latency distribution or double responses or both at an interval of about 4-5 ms. Typical first component responses were sometimes obtained by contralateral stimulation. Central conduction time in the brainstem, estimated for 15 motoneurones, was between 2.4 and 6.6 ms. It is concluded that the first component of the blink reflex is conducted through an oligosynaptic arc including one or more interneurones.

Adult↗
PubMed1979

H reflex analysis of segmental reflex excitability in flexor and extensor muscles.

In normal adults, H reflexes are commonly found only in the antigravity calf and flexor carpi radialis (FCR) muscles. However, these responses may be more widespread if agonist muscles contract. This study demonstrates that H reflexes may be found in the peroneal (P) and anterior tibialis (TA) muscles in the leg and the extensor digitorum communis (EDC) muscle in the arm on contraction of the antagonistic calf and flexor carpi radialis muscles, respectively. H reflexes were also elicited regularly in the EDC by passive extension of the wrist. The data indicate physiologic unity of comparably acting human antigravity muscles and their antagonists in both the upper and lower extremities, and imply an important functional role of group II afferent fibers in normal motor system activity.

Adult↗
PubMed1983

The reflex sympathetic dystrophy syndrome. An experimental study of sympathetic reflex control of subcutaneous blood flow in the hand.

Adrenergic sympathetic vasoconstrictor activity in subcutaneous tissue on the back of the hand was studied in 13 patients suffering from reflex sympathetic dystrophy syndrome. Subcutaneous blood flow was measured by the local 133Xe wash-out technique with simultaneous measurements on the healthy side as a control. The results indicated an increased subcutaneous blood flow in the affected hand compared with the control side. Proximal nervous blockade caused only a slight, 35% increase in subcutaneous blood flow on the affected side, whereas an increase of 122% was registered on the control side. Augmented sympathetic vasoconstrictor activity elicited by the local veno-arteriolar axon reflex mechanism or centrally elicited by head-up tilt caused an equal degree of arteriolar vasoconstriction in both hands. The results suggest that sympathetic vasomotor tone during resting conditions is reduced in the affected hand in patients with the reflex sympathetic dystrophy syndrome.

Aged↗
PubMed2001

Voluntary and reflex influences on the initiation of swallowing reflex in man.

The electrophysiological features of voluntarily induced and reflexive/spontaneous swallows were investigated. In normal subjects, swallows were elicited by infusing water either into the mouth (1-3 ml) or directly into the oropharyngeal region through a nasopharyngeal cannula (0.3-1 ml). For water infused orally, subjects were either requested to swallow voluntarily or instructed to resist swallowing and maintain the horizontal head position until swallowing occurred reflexively. Spontaneous saliva swallowing was investigated in patients with severe dysphagia who had a prominent clinical picture of suprabulbar palsy. Comparisons between different swallowing types were made by measuring the time interval between the onset of submental electromyographic activity (SM-EMG) and the onset of the upward movement of the larynx recorded by a movement sensor. This interval was less than 100 ms, even frequently less than 50 ms, in reflexive/spontaneous swallows, while in voluntarily induced swallows it was substantially longer. The rising time of submental muscle's excitation was also shorter in reflexive/spontaneous swallows. It was suggested that the triggering of voluntarily induced swallows commences more than 100 ms before the onset of swallowing reflex and that this mechanism is under the control of corticobulbar-pyramidal pathways. If the swallowing reflex is triggered within such a short period of time following the onset of SM-EMG, the central control by the bulbar swallowing center should be effective until the end of oropharyngeal swallowing.

Adult↗
PubMed2002

The perineorectal reflex The perineorectal reflex in health and obstructed defecation.

PURPOSE: Many females with obstructed defecation apply digital pressure on their perineum to facilitate defecation. This study investigated the impact of this maneuver on rectal tone. METHODS: Forty-five female patients with obstructed defecation were studied. Thirty-four patients (76 percent) regularly applied digital pressure on their perineum to facilitate defecation. Total colonic transit time was normal in 32 patients and prolonged in 13 patients. For comparison, 17 female controls were studied. With the subject in the left lateral position, a thin, "infinitely" compliant polyethylene bag was inserted into the rectum at 10 cm from the anal canal. Rectal tone was assessed by measuring variations in bag volume with a computer-controlled electromechanical air injection system. After an adaptation period of 15 minutes, digital pressure was applied to the anterior perineum by one of the authors (WRS). In a second recording session, the tonic response of the rectum to an evoked urge to defecate was examined. RESULTS: During the application of perineal pressure, all controls showed an increase in rectal tone (mean value, 52.8+/-19 percent). In the whole patient group, this response was significantly lower (mean value, 24.2+/-19 percent; P < 0.001). Eight of these patients (18 percent) showed no response at all. None of them applied perineal pressure. In the remaining 37 patients (72 percent), the perineorectal reflex was present but was significantly lower (mean value, 29.8+/-17 percent; P < 0.001). Thirty-four of these females (92 percent) stated that they applied perineal pressure on a regular basis to facilitate their defecation. All controls showed an increase in rectal tone during an evoked urge to defecate (mean value, 37.8+/-8 percent). In the patients, this response was significantly lower (16.7+/-6 percent). Eight of these patients showed no increase in rectal tone at all. These patients were the same patients in whom the perineorectal reflex was absent. Regarding the tonic response of the rectum to perineal pressure, no difference was found between patients with a normal colonic transit time and those with a prolonged colonic transit time. CONCLUSION: Digital pressure applied on the perineum results in an increase in rectal tone. This perineorectal reflex is present, although significantly lower, in the majority of females with obstructed defecation. This observation might explain why females with obstructed defecation frequently apply perineal pressure to facilitate defecation.

Adolescent↗