Reflex In Man Research Articles

The antagonistic effects of naloxone on acupuncture inhibition of the vibration-induced grasp reflex in man

It is known that the vibration-induced grasp reflex (VGR) is inhibited by the insertion of needles into the acupuncture points. Effects of intravenous administration of naloxone on acupuncture inhibition of the VGR were studied in human subjects to determine if acupuncture inhibition of the VGR might be mediated by endogenous opioids. Acupuncture inhibition of the VGR was partly reversed by the administration of naloxone. The VGR is mediated by a polysynaptic pathway through which the acupuncture inhibition that is reversed by naloxone is considered to occur. We conclude that the facilitatory influence of interneurons on motoneurons in the VGR was reduced by endogenous opioids to inhibit the VGR.

Antagonistic effect of naloxone on acupuncture inhibition of vibration-induced grasp reflex in man

Antagonistic effect of naloxone on acupuncture inhibition of vibration-induced grasp reflex in man

Inhibitory effect of acupuncture on the vibration-induced finger flexion reflex in man

Experiments were performed on 12 young and healthy subjects. The palmar side of the index finger was vibrated with a triangular wave form at randomly changed inter-stimulus intervals. This vibratory stimulation elicited a flexion movement of the index finger, which was depressed by acupuncture at ‘Wai-Kuan.’ It was generally observed that the depressive effect developed slowly and lasted for a long time. The depressive effect of acupuncture on this reflex was analyzed using a cross-correlation between the vibratory stimuli and motor unit spikes recorded from the flexor digitorum communis muscle. Cross-correlograms revealed two types of reflex responses. One of them showed a peak of time-locked spikes to the vibratory stimuli at a latency of 25 msec, which indicates monosynaptic activity of the motoneuron, and also showed time-unlocked spikes distributed in both sides of the peak, which implies polysynaptic activity. This type of response was frequently observed and was supposed to be elicited by the proprioceptive tonic vibration reflex. The other revealed no peaks, which indicates that only time-unlocked spikes to the stimuli are generated, and that these spikes are evoked via polysynaptic pathway. This type of response was supposed to be elicited by so-called exteroceptive vibration-induced finger flexion reflex. Since both types of reflex responses, i.e., mono- and polysynaptic ones, were equally depressed during acupuncture, it was concluded that the excitability of the motoneuron, a common output of this reflex, is lowered by acupuncture.

Technique and Clinical Applications of Latency Measurement of the Pudendoanal (Sacral Evoked) Reflex in Man

Technique and Clinical Applications of Latency Measurement of the Pudendoanal (Sacral Evoked) Reflex in Man

An experimental psychophysiological approach to human bradycardiac reflexes.

Bradycardic reflexes in man are both of scientific and clinical interest. Using the methods of experimental psychophysiology, control over relevant independent variables permits the study of fine-grained temporal physiologic response topographies, and of psychological factors that may modify the reflex. In addition, information can also be sought through interdisciplinary collaborations with experimental physiologists in order to shed light on the mechanism of the reflexes. These general features of the approach are illustrated by presenting data on two bradycardic reflex preparations: the laboratory dive analog, and the 90-degree negative tilt. The dive-analog studies have shown that a) the dive-reflex proper is a late-occurring bradycardia accompanied by a late-occurring vasoconstriction; and b) for the elicitation of this reflex, both breath-holding and face immersion are necessary. In addition, the physiologic manipulation of temperature affects the reflex in an inverse way over the range of 10 degrees to 40 degrees C, while the sense of control (a psychological variable) attenuates the reflex. The negative-tilt preparation produces a bradycardic response that is ideal as a Pavlovian unconditional response. Some Pavlovian conditioning arrangements, especially an "imaginational" form, do produce significant conditional bradycardic responding, and this has both potential clinical (e.g., biofeedback-related) and theoretical (e.g., S-R vs. S-S accounts of Pavlovian conditioning) applications. The paper ends with a comment on the cognitive paradigm shift in psychology. Although this shift is of importance, it is suggested that it is also important to "remember the response."

The effect of stimulus intensity and gape on electrically-evoked jaw reflexes in man

The changes in masseter EMG and biting force evoked by electrical stimulation of the lip were measured in normal people. Stimulation at noxious intensities elicited a characteristic, biphasic inhibitory response in the masseter EMG and a transient reduction in the biting force. The pattern of masseter inhibition and force change varied both with stimulus intensity and with inter-incisal separation. In general, the decrease in biting force was greater at intermediate jaw positions than in the open and closed positions. The duration of the EMG inhibitory period increased as the stimulus intensity increased but was independent of the jaw separation. Reflex thresholds could not be correlated with pain thresholds because subjects found it difficult to decide at what level an electrical stimulus became painful. Nevertheless this stimulation of high-threshold afferents may be useful in estimating the rate of relaxation of tension in the jaw muscles.

Recovery cycle of the masseter inhibitory reflex in man

The masseter inhibitory reflex from stimulation of the mental nerve has been recorded electromyographically in 10 healthy subjects. The recovery cycle of the two silent periods interrupting the tonic contraction of the masseter muscles have been studied with the paired shock technique. There was a clear dissociation between the recovery of early and late inhibition, the latter being far more affected by a preceding impulse. It is concluded that the two silent periods are mediated by separate neural nets. The differences with the recovery curves of the two components of the blink reflex are discussed.

Recruitment order of motor units during the stretch reflex in man

The recruitment pattern of single motor units contributing to the short- and long-latency periods of the stretch reflex was investigated in human adults. When non-tonic, a given unit responded to stretch during the long-latency reflex period. When made tonic, the same unit showed a reflex response during the short-latency period, while a higher threshold, non-tonic unit would respond during the long-latency period. The data show an orderly recruitment of motor units during both phases of the stretch reflex in man.

A quantitative study of flexion reflex in man

A quantitative study of flexion reflex in man

EMG-analysis of descending interlimb proprioceptive reflexes in man

EMG-analysis of descending interlimb proprioceptive reflexes in man

The afferent volleys responsible for spinal proprioceptive reflexes in man.

1. To define the neural volleys responsible for the Achilles tendon jerk and the H reflex, muscle afferent activity was recorded using micro-electrodes inserted percutaneously into appropriate fascicles of the tibial nerve in the popliteal fossa.2. The response of soleus muscle afferents to tendon percussion consisted of a dispersed volley, starting 3.5-7.0 ms after percussion, increasing to a peak over 6.5-11.0 ms, and lasting 25-30 ms, depending on the strength of percussion. Electrical stimuli to the sciatic nerve at a level adequate to evoke an H reflex but subthreshold for the M wave produced a more synchronized volley, the fastest fibres of which had conduction velocities of 62-67 m/s, and the slowest 36-45 m/s.3. The wave of acceleration produced by percussion subthreshold for the ankle jerk spread along the skin at over 150 m/s. Midway between the bellies of the gastrocnemii it consisted of a damped oscillation with four to five separate phases and maximum amplitude approximately one-twentieth of that recorded on the Achilles tendon.4. With ten primary spindle endings, tendon percussion subthreshold for the ankle jerk elicited two to five spike discharges per tap, the shortest interspike intervals being 4-7 ms. Tendon percussion elicited single discharges from two Golgi tendon organs, and altered the discharge pattern of a single secondary spindle ending. The degree of dispersion of the multi-unit muscle afferent volley can be explained by the pattern of discharge of primary spindle endings.5. Percussion on the Achilles tendon evoked crisp afferent volleys in recordings from nerve fascicles innervating flexor hallucis longus, tibialis posterior, the intrinsic muscles of the foot and the skin of the foot. Electrical stimuli delivered to the tibial nerve in the popliteal fossa at a level sufficient for the H reflex of soleus produced either a volley in muscle afferents from the intrinsic muscles of the foot or a volley in cutaneous afferents from the foot.6. For comparable stimuli in the two positions, the H reflex was inhibited but the Achilles tendon jerk enhanced when the ankle was dorsiflexed from 105 degrees to 90 degrees .7. The duration of the rise times of the excitatory post-synaptic potentials (e.p.s.p.s) produced in soleus motoneurones by electrical stimulation, and by tendon percussion subthreshold for the H reflex and the ankle jerk respectively, was estimated from post-stimulus time histograms of the discharge of voluntarily activated single motor units in soleus. The mean e.p.s.p. rise times were 1.9 ms for electrical stimulation and 6.6 ms for tendon percussion. There was evidence that the duration of the electrically evoked e.p.s.p. was curtailed by an inhibitory post-synaptic potential (i.p.s.p.) of only slightly longer latency than the e.p.s.p.8. The mechanically induced and electrically induced afferent volleys are not homogeneous volleys in group I a afferents from triceps surae. The afferent volleys differ in so many respects that it is probably invalid to compare the H reflex and tendon jerk as a measure of fusimotor activity. It is suggested that neither reflex can be considered a purely monosynaptic reflex.

Effect of brotizolam on the averaged photopalpebral reflex in man.

The photopalpebral reflex (PPR) is a useful method to assess level of arousal. Healthy males were given either brotizolam (0.0625, 0.125, 0.25 or 0.5 mg) or placebo within a double-blind, crossover design. Changes in PPR and subjective assessments were observed for 5 h after medication. Prolongation of the latencies of PPR were dose dependent, and the amplitude tended to be reduced. These effects appeared within 30 min, and lasted about 4 h. The dose-response curve of the maximum prolongation of the latencies was linear. Sleepiness and slight ataxia were observed after drug ingestion. Sleepiness was correlated with the prolongation of the PPR latencies. Brotizolam could be a potent hypnotic, with rapid onset and moderate duration of action, and it has no severe side-effects.

Sensitization of unmyelinated nociceptive afferents in monkey varies with skin type.

Sensitization of unmyelinated nociceptive afferents in monkey varies with skin type.

Comparative effects of electroacupuncture and transcutaneous nerve stimulation on the human blink reflex

The effects of low frequency (2 Hz) high intensity (10–12 mA) (electroacupuncture, EA)and of high frequency (100 Hz) low intensity (2 mA) (transcutaneous nerve stimulation, TNS) conditioning stimuli were studied on the nociceptive component (R2) of the blink reflex in normal volunteers. EA induced a progressive and moderate partially naloxone-reversible depression in the R2 response. In contrast, TNS induced a rapid and major depression in this reflex. In this latter case, naloxone failed to produce any reversal effect. These two patterns of data are discussed and further electrophysiological studies provide some evidence for two different mechanisms in the depressive effects of EA and TNS upon the nociceptive component of the blink reflex in man.

Cardiovascular responses to lateral semicircular canal stimulation in man

The cardiovascular effects of aural irrigation with water at 37 degrees C (control subjects, n = 6) or 44 degrees C (experimental subjects n = 11) were assessed from measurements of heart rate, brachial arterial blood pressure and forearm blood flow. The occurrence and intensity of vestibular stimulation was assessed from the electronystagmogram. The procedure had no significant effect on cardiovascular variables in control subjects or in subjects who were exposed to vestibular stimulation but who were not nauseated by it (n = 6). Those subjects who felt nauseous (n = 5) showed a tachycardia and forearm vasodilatation. These results provide no evidence that vestibular stimulation contributes to orthostatic reflexes in man.

Inhibitory effect of acupuncture on the vibration-induced grasp reflex in man

The effect of acupuncture on the grasp reflex caused by mechanical vibrations of fingers produced by a cylinder-type vibrator (120 Hz) was studied in healthy man. As the hand grasped the vibrator during vibration, the volar surface of all fingers was simultaneously stimulated, resulting in a gradually increased force of the grasp, the vibration-induced grasp reflex (VGR). The VGR was inhibited by acupuncture with needles inserted into three acupuncture points (Shou Sanli, Chicheng and Szutu), but not into other sites in the hand.

An electromyographic study of jaw opening and closing reflexes in man

The electromyographic activity of the right masseter and digastric muscles was recorded in 10 subjects. A jaw-opening reflex was observed shortly after a mechanical stimulation in subjects performing clenching and active jaw-opening exercises. The latency of this reflex activity was about 28 ms, coinciding with the termination of the silent period of the masseter muscle. The experiments show that this opening reflex can occur without masseter spindle-unloading and may respond to low-threshold afferents.

Long loop and spinal reflexes in man during preparation for intended directional hand movements

Long loop and spinal reflexes in man during preparation for intended directional hand movements

Physiological study of the averaged photopalpebral reflex in man : H. Isozaki, M. Tanaka, Y. Mizuki and K. Inanaga (Kurume, Japan)

Physiological study of the averaged photopalpebral reflex in man : H. Isozaki, M. Tanaka, Y. Mizuki and K. Inanaga (Kurume, Japan)

Labial reflexes in man during performance of an oral reaction time task : M. Bratzlavsky and H. Vander Eecken (Ghent, Belgium)

Labial reflexes in man during performance of an oral reaction time task : M. Bratzlavsky and H. Vander Eecken (Ghent, Belgium)