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At least 19 recordsLinked to original sources
PubMed1979

Babinski reflex and the CUT reflex--a comparative study.

The Babinski reflex and the CUT reflex were examined in 150 neurological patients and 20 controls. A positive CUT reflex occurred more frequently than a positive Babinski reflex in the patient material as a whole, and in different diagnostic groups. However, there was a low grade of correspondence between a positive CUT reflex and a positive Babinski reflex. There were many positive CUT reflexes in the group of normal persons. In a number of cases the examination of the CUT reflex was impossible because of lack of strength or incooperability. The study indicates that the CUT reflex and the Babinski reflex are not comparable phenomena.

Adolescent↗
PubMed1979

The Bezold reflex: a special case of the left ventricular mechanoreceptor reflex.

Our previous finding that increasing myocardial contractility caused reflex systemic hypotension, the left ventricular (LV) mechanoreceptor reflex, suggested that the classical Bezold reflex (systemic hypotension and bradycardia after intracoronary administration of veratrum alkaloids) may be initiated by these same LV mechanoreceptors. In our working LV preparation with the coronary and systemic circulations isolated and perfused separately, intracoronary injection of veratrum alkaloids, like that of catecholamines or ouabain, had a positive inotropic effect which produced the hypotensive response typical of the LV mechanoreceptor reflex. To test directly if veratridine's positive inotropic effect initiates the Bezold reflex, verapamil, which blocks the slow Ca(2+) channels of myocardial cells but leaves intracardiac nerves unaffected, was injected by the intracoronary route to prevent the increased contractility from intracoronary injection of veratridine which also abolished the reflex hypotension, demonstrating conclusively that increasing myocardial contractility and thereby activating LV mechanoreceptors but not chemoreceptors initiates the Bezold reflex. Contrariwise, decreasing contractility or cardiac asystole by administration of tetrodotoxin, verapamil, or EDTA resulted in an increase in the systemic resistance, indicating that changes in the magnitude of the stimulus initiating the LV mechanoreceptor reflex (i.e., changes in myocardial contractility) lead to directionally opposite changes in peripheral resistance, as in the sino-aortic mechanoreflexes. Thus, it is concluded that the Bezold reflex is a special case of the LV mechanoreceptor reflex. The latter, by means of feedback mechanisms, functions normally by continuously matching the peripheral resistance to the LV contractile state so as to maintain the arterial pressure constant, thereby playing an important role in blood pressure regulation.

Animals↗
PubMed1976

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

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.

Animals↗
PubMedDate not supplied

[Effect of polysynaptic flexion reflex on monosynaptic reflexes of calf muscles prior to and following intramuscular injection of ethylbenzatropine in drug-induced muscle rigidity].

In patients with drug-induced parkinsonism and in healthy subjects the effect of stimulation of low-threshold skin fibres of sural nerve producing the polysynaptic flexion reflex of the short head of the biceps femoris muscle on the monosynaptic H reflex of calf muscles was studied before and after administration of ethylbenzatropine. In healthy subjects stimulation of low-threshold skin nerve was followed by facilitation of H reflex in the time of 70 to 200 msec. from the conditioning stimulation to the test stimulation. After one single intramuscular dose of ethylbenzatropine this late facilitating effect disappeared. In patients with drug-induced parkinsonism stimulation of afferent fibres of flexion reflex failed to cause late facilitation of H reflex and one dose of ethylbenzatropine brought no changes. During systematic administration of the drug an evident tendency for facilitation of H reflex was observed, similarly as in healthy subjects. The results obtained in healthy subjects and in patients with drug-induced parkinsonism are explained as evidence of inhibitory action of noradrenaline in certain chains of spinal interneurons, since noradrenaline release in the spinal cord is determined by the striatal equilibrium between the cholinergic and dopaminergic systems. The corrective action of ethylbenzatropine would depend on its central action on certain spinal chains of interneurons determining transmission of impulses from dermal afferent nerves to alpha motoneurons.

H-Reflex↗
PubMedDate not supplied

[Soleus muscle reflexes evoked by stimulation of the posterior tibial nerve compared to tendon reflexes in man (author's transl)].

The characteristics of the reflex response evoked in the soleus muscle after stimulation of the posterior tibial nerve at the ankle were contrasted with the achilleus tendon reflex in 14 healthy volunteers and in a group of selected neurological patients. The following features were examined: conditions of stimulation including stimulation frequency; appearance of reflex activity in muscles other than soleus, effect of the vibratory stimulation, interactions with voluntary contraction. Moreover, a reflex response is described in the soleus following stimulation of the sural nerve. The results have shown a marked jitter in latencies of the responses, a pattern of coactivation of antagonistic muscles, a clear increase of amplitude under vibration or voluntary contraction, normal responses both in spasticity and in S1 radiculopathy with achilleus areflexia. All these data differ from those observed with the tendon jerk of the same amplitude and differentiate the two responses. It is concluded that the reflex evoked by stimulation of the tibial nerve at the ankle is a polysynaptic response of cutaneous origin.

Achilles Tendon↗
PubMed1977

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

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

Achilles Tendon↗
PubMed1978

Studies on the mechanism of reflex vasodilatation. The cholinergic component in the baroreceptorial reflex in the dog.

This study was designed to investigate whether the cholinergic system is involved in the genesis of the reflex vasodilatation which follows the systemic hypertension induced by fast intravenous injection of norepinephrine in the dog. Accordingly, in 7 dogs the gracilis muscle was isolated and perfused and the reflex evoked. The analysis of the integrated areas of vasodilatation after atropine pretreatment showed a significant decrease of the reflex response in the perfused circulation. In fact, the mean value of the integrated areas of vasodilatation which was 66 +/- 8 mm Hg/min in the control condition, was reduced to 45 +/- 4 mm Hg/min after administration of atropine in the gracilis artery; meanwhile the integrated areas of systemic hypertension did not show any change. Phentolamine intra-arterial administration completely abolished the reflex. These results suggest the existence of a cholinergic component in the reflex vasodilatation induced by transitory baroreceptorial stimulation.

Animals↗
PubMed1979

Somatosensory evoked potential of the stretch-reflex (T-reflex).

Averaging of EEG recorded monopolarly from C3, contralateral to the activated limb, in the stretch reflex shows the presence of somatosensory evoked potential (SSEP) with characteristic shape: four constant waves--P29, N84, P202 and N294, and four inconstant waves--N31, P74, P99 and N123. Comparison of this SSEP with the SSEP in children, evoked in the stretch reflex, shows shorter latencies of the waves in adults. On the basis of data from the different series of experiments, it is assumed that kinesthetic signalization plays a dominant role in the genesis of SSEP of the T-reflex. Studies have shown that SSEP of the T-reflex is succeptible to habituation upon long repetition of the stretch reflex.

Achilles Tendon↗
PubMedDate not supplied

Admittance values associated with the acoustic reflex and reflex decay.

Acoustic stapedial reflexes were elicited from 10 normal S's in each of three age groups. Susceptance and conductance values were measured for each subject in both the unreflexed and reflexed states and at 10-sec intervals during a continuous, reflex-sustaining stimulation with pure tones. Percentage of reflex decay over time was noted for each group and as a function of stimulus frequency and measurement mode. No significant age group differences were noted. Significant stimulus frequency and measurement mode differences were presented to represent "normal" reflex decay.

Adult↗
PubMed1976

[Descending long-loop reflexes in the human spinal cord I. Facilitation of the triceps surae H reflex following stimulation of forelimb afferences (author's transl)].

The H reflex in the triceps surae muscle was elicited by just supraliminal stimulation of the tibial nerve. It was conditioned by paired impulses to the brachial plexus or the forelimb nerves and in some cases to other sites of the body. With a conditioning test interval of 32-47 msec a facilitation occurred which reached its maximum at about 80 msec and lasted for about 400 msec. The facilitation evoked by ipsilateral conditioning had a shorter latency than that from contralateral (ipsilateral: 32-42 msec, contralateral; 37-47 msec). The facilitation at the optimum interval (about 80 msec) ranged between 1;5 and 11.3 times of the control values. Ipsilateral conditioning was slightly more effective than the contralateral one (Fig. 1, 2). Stimulation of different forelimb nerves at an interval of 80 msec showed only insignificant differences in the amount of facilitation but was more effective than skin stimulation in the most cases (Fig. 3). Varying the intensity of the conditioning stimulus showed that facilitation occurred with just perceptable stimuli but it became more pronounced as soon as pain threshold (2-3 time of perception threshold) was exceeded (Fig. 3). This suggests that facilitation was mainly due to activation of nociceptor afferents. From the onset of facilitation and the conduction velocities of the respective forelimb and hindlimb afferents (cf. 6) a central reflex lantency of about 43 msec was calculated. To get further insight into the central connections of the reflex loop the H reflex was conditioned by paravertebral stimulation at C5 and L1 level. Both stimuli caused a distinct facilitation. However, the latency of the onset was 10-15 msec shorter with lumbar stimulation than with cervical stimulation. This and the similar time course of facilitation seen in animal experiments (12) suggest that an early part of facilitation is mediated via a descending propriospinal pathway. The major part, however, is supposed to be mediated via supraspinal pathways and seems to be related to a startle response.

Animals↗
PubMed1975

Amygdala and masseteric reflex. II Mechanism of the diphasic modifications of the reflex elicited from the "defence reaction area". Role of the spinal trigeminal nucleus (pars oralis).

It has been demonstrated (Gary Bobo and Bonvallet 1975) that long-lasting stimulation of the "amygdaloid area for the defence reaction" (basal nucleus, pars magnocellularis) elicits, after an initial facilitation, a delayed inhibition of the monosynaptic masseteric reflex (MR), while stimulation of the amygdalofugal fibers running in the ansa lenticularis provokes an immediate inhibition of the reflex. In present study, the structure which mediates these inhibitions has been identified. Using combined techniques of limited transections, localized coagulations and localized stimulation and recording, it has been demonstrated that these ingibitions are mediated by the rostral portion of the spinal trigeminal nucleus, the subnucleus oralis (NO). After localized coagulation of this nucleus, or after lesions which interrupt slectively the connections between the NO and the masticatory nucleus, long-lasting stimulation of the basal nucleus elicits only well maintained facilitation of the MR. Hence, the delayed decrease in amplitude of the reflex, observed during stimulation of the basal nucleus in the preparations with intact brain, cannot be explained by the reversal of an initial facilitatory influence to an ingibitory one. The one ingibition of the reflex is due to the superimposition, on a background of sustained facilitation of the masseteric motoneurons, of the inhibitory influence exerted on the monosynaptic masseteric circuit by a trigeminal sensory nucleus, itself activated by delayed discharges of the basal nucleus. A tentative representation of the dual control exerted on the masseteric activity by the basal nucleus is given in Fig. 9. The functional implications of this dual control during the "defence reaction" are briefly discussed.

Amygdala↗
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↗
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↗
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↗
PubMed1975

[Electrophysiological analysis of facial reflex in monkeys: trigemino-naso-labial reflex].

Electrical stimulation of the awake monkey's supra orbital nerve, elicits two successive reflex discharge in both naso-labialis muscles (NL). The responses have a similar high threshold. Similar responses are also elicited on electrical stimulation of the facial skin, whereas flash, click or tapping on the muscle belly are ineffective. These responses bear some resemblances to those obtained in orbicularis oculi muscles ; but the higher threshold and the different organization of the NL responses would suggest that such reflexes may serve a different function from that of the blink reflex.

Animals↗
PubMed1977

Electrodiagnostic investigation of motor neuron and spinal reflex arch (H-reflex) in spinal cord injury.

Twenty patients with spinal cord injury underwent serial electromyographic examinations. Fibrillation potentials and positive waves were noted in six patients in the spinal shock phase. In another subject, these potentials were found 27 months after injury. Our finding of significant slowing in the NCV of both nerves, indicates that lower motor neurons are indeed affected by upper motor neuron lesions. The H-reflex studies showed an increase in the mean H/M ratio. This may indicate an increase of reflex motor neuron excitability. No clear correlation was found between this increase and the degree of clinical spasticity. With repeat investigations, after a period of physical activity, a trend to reduction of the H/M ratio was noted with no clinical confirmation of reduction in spasticity. These findings emphasise the need for not assigning diagnostic terms to EMC abnormalities, but rather identifying them as neurophysiological changes which must be interpreted in the light of the clinical picture.

Adolescent↗