Finger Flexion Reflex Research Articles

Inhibitory Effect of Acupuncture on Vibration-Induced Finger Flexion Reflex in Humans: Comparisons Among Radial, Median, and Ulnar Nerve Stimulation.

Vibration-induced finger flexion reflex (VFR) is inhibited with acupuncture to TE 5 or LI 4 at the skin innervated by the radial nerve. The aim of this study was to determine if acupoints in regions innervated by the radial nerve are specific to inhibit VFR. This experiment was performed using a crossover design with 3 acupuncture groups (needle insertion to the right LU 11, PC 9, or SI 1) and a control group (no needle treatment). Each acupoint was randomly needled on separate days. Ten healthy volunteers were recruited for this study. VFR was induced by applying vibration on the volar side of the right middle fingertip. An acupuncture needle was inserted in the acupoint and retained for 5 minutes. For the main outcome measure, maximum finger flexion force (MFFF) was measured during vibration and was compared among four groups. MFFFs in the acupuncture groups were significantly lower (p<0.05) than that in the control group. However, no significant difference was observed in MFFFs in the three intervention groups after acupuncture to LU 11, PC 9, and SI 1. Acupuncture to the right LU 11, PC 9, or SI 1 point inhibited the ipsilateral VFR, which suggests that afferent inputs from the radial nerve with needle insertion were not specific, compared with those from the median and ulnar nerves to suppress neuronal activities in the VFR reflex circuits.

Inhibitory Effect of Needle Penetration on Vibration-Induced Finger Flexion Reflex in Humans

BackgroundVibration-induced finger flexion reflex (VFR) in the upper extremity is inhibited by needle insertion acupuncture to the large intestine 4 (LI4) at the hand. This claim has a limitation because the inhibitory effect is deduced only from reduction in the maximum finger flexion (FF) force during the tonic flexion reflex by vibratory stimulation after acupuncture.MethodsThe study was a crossover design with two conditions—acupuncture and control—to which 16 healthy volunteers were subjected. VFR in the upper extremity was induced by applying vibratory stimulation on the volar side of the middle fingertip of the right hand, before and after acupuncture at the right LI4 in 16 healthy volunteers. We measured the area under the curve (AUC) of finger flexion force and surface electromyogram (EMG) in the flexor muscles, in addition to the maximum FF force during vibratory stimulation. We compared AUC, surface EMG and maximum FF force in the acupuncture condition with those in the control condition. We also estimated the correlation between AUC, surface EMG and maximum FF force.ResultsAUC, surface EMG and maximum FF force were significantly reduced (p <0.01) after acupuncture compared with those of the control group. A strong correlation was observed in maximum FF force versus AUC (r=0.98, p <0.01) and surface EMG (r=0.77, p <0.01).ConclusionsAcupuncture at ipsilateral LI4 inhibited tonic activities in the finger flexor muscles during VFR, which suggests that afferent input with needle penetration has inhibitory effect on the motor neuronal activities in the reflex circuits of VFR.

Inhibitory Effect of Pain-Eliciting Transcutaneous Electrical Stimulation on Vibration-Induced Finger Flexion Reflex in the Human Upper Limb

We studied the effects of non-pain transcutaneous electrical stimulation (TES) and pain-eliciting TES on vibration-induced finger flexion reflex (VFR) in 12 healthy volunteers. Tonic finger flexion reflex in the upper limb was induced by the application of vibratory stimulation on the volar side of the middle fingertip in the right hand before and after TES. Non-pain TES or pain-eliciting TES was applied on the skin between the bases of the first and second metacarpals in the right hand dorsal area in a crossover design. Pain-eliciting TES inhibited VFRs significantly (Fisher's PLSD, p <0.01), compared to those of the time-control group during and after TES. VFRs were reduced approximately to 63.8% and 78.6% of prestimulation flexion force during and after pain-eliciting TES, respectively. Nonpain TES did not inhibit VFR. These results suggest that pain-conducting afferent fibers have inhibitory neuronal connection over the ipsilateral reflex circuits of VFR in the upper limb.

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.

Effect of acupuncture at the Hoku point on vibration-induced finger flexion reflex in man: comparison between press needle technique, electroacupuncture, and in-situ technique.

Effects of press needle technique (PN), electroacupuncture (EA), or in-situ technique (IS) on vibration-induced finger flexion reflex (VFR) were examined in 31 healthy adults. VFR, which is tonic finger flexion evoked by vibration applied to the finger tip, was induced by vibrating the volar side of the middle finger tip before and after acupuncture. Acupuncture was applied to the Hoku point on both sides. The three techniques, each studied on separate days, inhibited VFR and there was no significant difference in VFR inhibition among the three techniques (percentage of pre-acupuncture VFR was 71.5 +/- SE 2.2% after PN, 72.6 +/- SE 2.4% after EA, and 75.6 +/- SE 2.8% after IS). The results suggest that afferent signals from muscles contracting due to electrical stimulation had no significant effect on the reflex arcs of VFR; and that the intradermal stimulation by acupuncture played a significant role in VFR inhibition.

Inhibitory effect of acupuncture on the finger flexion reflex induced by finger tip vibration.

The effect of acupuncture on finger flexion reflex, caused by mechanical vibration applied to the finger tip, was studied by using the cross-correlation function. A stainless steel acupuncture needle was inserted into the acupuncture point called "Wai-Kuan" for 10 min. Acupuncture inhibited the reflex and suppressed the two modes seen in the cross-correlogram between unitary EMG activity of the muscle flexor digitorum superficialis and finger tip vibration with random frequency. The recovery of the primary mode, which may be via the spinal monosynaptic reflex loop, was significantly earlier than the recovery of the secondary mode, which may be via the supraspinal reflex long loop. This suggests that the distinct inhibitory effect of acupuncture takes place on the reflex at spinal and supraspinal levels.

Inhibitory effect of acupuncture on the finger flexion reflex induced by finger tip vibration (NSR 00185)

Abstract The effect of acupuncture on finger flexion reflex, caused by mechanical vibration applied to the finger tip, was studied by using the cross-correlation function. A stainless steel acupuncture needle was inserted into the acupuncture point called “Wai-Kuan” for 10 min. Acupuncture inhibited the reflex and suppressed the two modes seen in the cross-correlogram between unitary EMG activity of the muscle flexor digitorum superficialis and finger tip vibration with random frequency. The recovery of the primary mode, which may be via the spinal monosynaptic reflex loop, was significantly earlier than the recovery of the secondary mode, which may be via the supraspinal reflex long loop. This suggests that the distinct inhibitory effect of acupuncture takes place on the reflex at spinal and supraspinal levels.

Difference in electromyographic response of finger flexion muscles between tonic vibration reflex and finger flexion reflex induced by finger tip vibration

Vibratory stimulus applied to the skin of the finger tip induced flexion reflex in that finger. By using the cross-correlation function, characteristics of this reflex were compared to those of tonic vibration reflex (TVR). In the cross-correlogram between unitary electromyogram (EMG) activity in the muscle flexor digitorum superficialis and vibratory stimulus with random frequency, one mode was seen in TVR, and two modes in finger flexion reflex. The secondary mode was significantly wider than the primary mode. Thus it may originate from skin mechanoreceptors and manifest via a reflex center involving a long loop.

Effect of acupuncture stimulation on the finger or toe flexion reflex induced by vibration to the human skin

Effect of acupuncture stimulation on the finger or toe flexion reflex induced by vibration to the human skin

Exteroceptive vibration-induced finger flexion reflex in patients with peripheral nerve injuries

Exteroceptive vibration-induced finger flexion reflex in patients with peripheral nerve injuries

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.

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

The effect of acupuncture on the tonic finger flexion reflex caused by mechanical vibration of the index finger was studied in healthy man. The volar side of the index finger was tapped by a vibrator (100 Hz), while flexion forces were recorded. A silver needle inserted into the acupuncture point (Wai-Kuan) inhibited the vibration-induced finger flexion reflex. In this study, the inhibitory effect of acupuncture on the reflex contraction, rather than pain sensation and analgesia, was demonstrated.

Exteroceptive vibration-induced finger flexion reflex in man.

A tonic finger flexion reflex, induced by mechanical vibration (100 Hz) of the fingers, was studied in 20 healthy subjects. The outcome of nerve blocking experiments indicated that the reflex is mainly exteroceptive, distinct from the tonic vibration reflex of muscle spindle origin. Mechanoreceptors with fast conducting nerve fibres in the distal phalanx seem to constitute the major afferent source. We suggest that afferent signals from such receptors by a feedback mechanism can influence the motor performance of the exploring fingers.