• The Korean Journal of Physiology
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• 제21권1호
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• pp.67-77
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• 1987

Effect of intravenously injected clonidine on the flexion reflex was studied in 15 decerebrated and spinalized cats. The flexion reflex was elicited by electrical stimulation of the tibial nerve or the common peroneal nerve and it was recorded as single unit activity from filaments of the L6 or L7 ventral roots. In order to obtain the late flexion reflex discharges, $A{\delta}$ and C afferent fibers were stimulated with single or train electrical pulses respectively. The flexion reflex, especially the late component, was markedly inhibited after intravenous administration of clonidine. The clonidine-induced inhibition of the flexion reflex was compared before and after treatment of the animals respectively with yohimbine and naloxone. The inhibitory effect on the flexion reflex of clonidine was not altered by naloxone, a ${\mu}-opioid$ receptor blocker, whereas it was completely blocked by yohimbine, an ${\alpha}_2-adrenergic$ antagonist. These results indicate that clonidine inhibits the flexion reflex through excitation of ${\alpha}_2-adrenoceptors$ even at the spinal cord level.

• The Korean Journal of Physiology
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• 제15권2호
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• pp.67-71
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• 1981

Experiments were conducted to test morphine sensitivity of the flexion reflex in the anemic decerebrate cats. Animals were immobilized with gallamine triethiodide(Flxaedil) and were artificially ventilated. The sural nerve was electrically stimulated(20V, 0.5 msec) and the flexion reflex was obtained by recording compound action potentials from the nerve innervated to the semitendinosus muscle. Intravenous injection of morphine $(0.5{\sim}2.0\;mg/kg)$ was found to have following effects on the flexion reflex. 1) Morphine tended to depress the early component of the flexion reflex and the effect was widely variable between animal preparations. 2) Morphine significantly depressed the late component of the flexion reflex, the effect being proportional to the dose of morphine. 3) The morphine effect on the flexion reflex was reversed by a small dose of naloxone hydrochloride$(0.025{\sim}0.1\;mg/kg)$. 4) Naloxone hydrochloride alone did not appear to facilitate the flexion reflex. 5) The main site for the morphine action was found to be the brain stem. From these results and those reported in literatures, we conclude that the late component of the flexion reflex well represents the pain sensation, thus the late component of the flexion reflex can be used as a reasonable subjective index of pain in experimental animals.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1183-1194
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• 2006

The aim of this study was to identify the characteristics of the flexion withdrawal reflex modulated by the hip angle and hip movement in spinal cord injury (SCI). The influence of the hip position and passive movement were tested in 6 subjects with chronic SCI. Each subject placed in a supine position and lower leg was fixed with the knee at 5 -45 degree flexion and the ankle at 25-40 degree plantar flexion. A train of 10 stimulus pulses were applied at 200 Hz to the skin of the medial arch to trigger flexion reflexes. From results of the regression analysis, static properties of normalized muscle activation of flexor muscles have the linear relationship with respect to hip angle (P< 0.05). In order to verify the neural contribution of flexion reflex, we compared the static and dynamic gains of estimated muscle activations with measured EMG of ankle flexor muscle. Form this study, we postulate that the torque and muscle response of flexion withdrawal reflex have linear relationship with hip angle and angular velocity.

• The Korean Journal of Pain
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• 제13권2호
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• pp.175-181
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• 2000

Background: Pain is often measured using psychophysical scaling techniques. However, all of these methods found their limits, since they were based on the subjective sensations reported by the subjects. It is, therefore, desirable to validate psychophysical pain measures by simultaneously measuring some physiological correlate of nociception. We studied an objective method for measuring pain in human volunteer using R(III) nociceptive flexion reflex. Methods: Four different intensity of electrical stimuli between perception and 1.4 times the R(III) nociceptive flexion threshold were delivered to the sole of the feet in 8 normal volunteers. We measured the flexion reflex activity in the skin over the ipsilateral tibialis anterior muscle and subjects rated each stimulus on a visual analog scale (VAS) Results: Both R(III) nociceptive flexion reflex activity and VAS ratings showed a linear relationship with stimulus intensity and with each other in all volunteers. Conclusions: R(III) nociceptive flexion reflex elicited through electrical stimulation may used as an objective pain measurement, previsionary based on our study paradigm.

• The Korean Journal of Physiology
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• 제15권2호
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• pp.73-81
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• 1981

Experiments were conducted in ischemic decerebrate cats to study the effects of electroacupuncture and electrical stimulation of peripheral nerve on pain reaction. Flexion reflex was used as an index of pain. The reflex was elicited by stimulating the sural nerve(20 V, 0.5 msec duration) and recorded as a compound action potential from the nerve innervated to the semitendinosus muscle. Electroacupuncture was performed, using a 23-gauge hyperdermic needle, on the tsusanli point in the lateral upper tibia of the ipsilateral hindlimb. The common peroneal nerve was selected as a peripheral nerve which may be associated with electroacupuncture action, as it runs through the tissue portion under the tsusanli point. Both for electroacupuncture and the stimulation of common peroneal nerve a stimulus of 20 V-intensity, 2 msec-duration and 2 Hz-frequency was applied for 60 min. The results are summerized as follows: 1) The electroacupuncture markedly depressed the flexion reflex; this effect was eliminated by systemic application of naloxone $(0.02{\sim}0.12\;mg/kg)$, a specific narcotic antagonist. 2) Similarly, the electrical stimulation of the common peroneal nerve significantly depressed the flexion reflex, the effect being reversed by naloxone. 3) When most of the afferent nerves excluding sural nerve in the ipsilateral hindlimb were cut, the effect of electroacupuncture on the flexion reflex was not observed. Whereas direct stimulation of the common peroneal nerve at the proximal end from the cut resulted in a significant reduction of the flexion reflex, again the effect was reversible by naloxone application. 4) Transection of the spinal cord at the thoracic 12 did not eliminate the effect of peripheral nerve stimulation on the flexion reflex and its reversal by naloxone, although the effect was significantly less than that in the animal with spinal cord intact. These results suggest that: 1) the analgesic effect of an electroacupuncture is directly mediated by the nervous system and involves morphine-like substances in CNS, 2) the site of analgesic action of electroacupuncture resides mainly in the brainstem and in part in the spinal cord.

• The Korean Journal of Pain
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• 제14권1호
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• pp.19-25
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• 2001

Background: Transcutaneous electrical nerve stimulation (TENS) has been used widely, but its effects are controversial. This is probably due to the varying intensity and type of pain. We designed a study to assess the effects of the TENS on the RIII nociceptive flexion reflex as the resting pain level and the temporal summation as a repeated, movement related pain in 7 normal volunteer subjects. Methods: High frequency (80 Hz), non-noxious TENS was applied over the left popliteal fossa for 20 minutes. Ipsilateral RIII reflexes induced by single electrical stimulus and temporal summation of pain responses to repeated stimuli (five stimuli at 2 Hz) were recorded before, during (just before stopping), and subsequently at 20 minutes after TENS. Results: R (III) nociceptive flexion reflex activity during and after TENS was more significantly decreased than before treatment. However, the temporal summation threshold was not changed. Conclusions: We conclude that high frequency, non-noxious TENS could be effective on resting pain relief in the same segment but not on the movement related pain.

• 대한의용생체공학회:의공학회지
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• 제31권5호
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• pp.344-350
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• 2010

The aim of this study was to investigate the characteristics of the flexion withdrawal reflex modulated during Lokomat treadmill walking in people with spinal cord injury. The influence of the limb position and movement were tested in 5 subjects with chronic spinal cord injury. EMG activities from tibialis anterior and moments of the hip joint elicited by the foot stimulation were examined during Lokomat treadmill walking. To trigger the flexion withdrawal reflex during Lokomat treadmill walking, a train of 10 stimulus pulses was applied at the skin of the medial arch. The TA EMG activity was modulated during gait phase and the largest TA reflex was obtained after heel-off and initial swing phase. During swing phase, TA EMG was 40.9% greater for the extended hip position (phase 6), compared with flexed hip position (phase 8). The measured reflex moment of the hip joint was also modulated during gait phase. In order to characterize the neural contribution of flexion reflex at the hip joint, we compared estimated moments consisted of the static and dynamic components with measured moment of the hip joint. The mean static gains of reflex hip moments for swing and stance phase are -0.1, -0.8, respectively. The mean dynamic gains of reflex hip moments are 0.25 for swing, 0.75 for stance phase. From this study, we postulate that the joint moment and muscle response of flexion withdrawal reflex have the phase-dependent modulation and linear relationship with hip angle and angular velocity for swing phase during Lokomat treadmill walking.

• The Korean Journal of Physiology
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• 제17권2호
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• pp.169-176
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• 1983

It is well known that the acupuncture has been used effectively for the relief of certain types of pain. Although the precise mechanism of action of acupuncture analgesia is unknown, it is generally accepted that their analgesic properties are related to the activation of endogenous opiate system in central nervous system. And it is suggested that pain-relieving properties of acupunture may be related to a stimulation of peripheral nerve underlying the acupuncture point on the skin. However, the efficacy of acupuncture has no relationship between the site of pain and the acupuncture point. Consequently, the present study was undertaken to investigate electroacupuncture analgesia in relation to the site of peripheral nerve stimulation. Cats were decerebrated ischemically and the flexion reflex as an index of pain was elicited by stimulating the sural nerve (20V, 0.5 msec duration) and recored as a compound action potential from the nerve innervated to the posterior biceps femoris muscle in the ipsilateral hindlimb. Bilateral common peroneal nerve and contralateral superficial radial nerve were selected as the site of peripheral nerve stimulation. For the stimulation of peripheral nerve, a stimulus of 20 V intensity, 2 msec-duration and 2 Hz-frequency was applied for 60 min respectively. The results obtained are summarized as follows: 1) Both stimulation of contralateral common peronal nerve and contralateral superficial radial nerve did not change the flexion reflex and there were no significant differences between them. 2) Stimulation of ipsilateral common peroneal nerve markedly depress the flexion reflex, the effect being reversed by naloxone application. These results suggest that stimulation of ipsilateral common peroneal nerve has the analgesic effect but both stimulation of contralteral common peroneal nerve and contralateral superficial radial nerve to the pain site where flexion reflex was elicited have no analgesic effect.

• 한국전문물리치료학회지
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• 제14권4호
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• pp.7-13
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• 2007

The purpose of this study was to investigate correlations among objective measurements of spasticity in patients with brain lesions. Thirty-two stroke and traumatic brain injury subjects participated in the study. Spasticity was quantified using the knee first flexion angle, relaxation index obtained from a pendulum drop test, and the amplitude of a knee tendon reflex test. Pearson's product correlation coefficient was used to examine relationships among these measurements of spasticity. There was a significant positive correlation between the relaxation index and knee first flexion angle in patients with brain lesions (r=.895, p<.01). There was also significant negative correlation between the amplitude of knee tendon reflex and relaxation index (r=-.612, p<.01), and between amplitude and knee first flexion angle (r=-.537, p<.01). Thus, it is possible to use the knee first flexion angle as an objective measure of spasticity, rather than relaxation index, which is more complicated to obtain. Further studies are needed to explore the effects of functional improvement and long-lasting carryover effects of spasticity using a simple objective measure such as the knee first flexion angle from a pendulum test.

• The Korean Journal of Physiology
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• 제21권1호
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• pp.79-90
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• 1987

The present experiment was performed in 35 normal male volunteers to evaluate the effect of electroacupuncture on the human nociception more clearly and to demonstrate the effect of different parameters of electrical stimulation through acupuncture needles. The threshold of the pain(Tp) and the nociceptive flexion reflex(Tr), the threshold for intolerable pain(Tip) and that for obtaining maximal reflex response(Tmr) were studied before and after electroacupuncture performed on the acupoints of tsusanli and hsuanchung. 1) For the pricking pain, electroacupuncture with intermittent stimulation induced a significant decrease in Tp which recovered after removal of the needles. There was no significant change in other thresholds. 2) For the dull pain, electroacupuncture with intermittent stimulation produced a significant increase in Tp which continued after removal of the needles. But there was no signifcant change in Tip. Electroacupuncture with continuous stimulation induced a slight increase in Tp. 3) After resting without electroacupuncture, Tp and Tip of the dull pain were slightly decreased. These results suggest that electroacupuncture had no significant analgesic effect on the pricking pain induced by electrical stimulation of the foot skin. However, electroacupuncture with intermittent stimulation had significant analgesic effect on the weak dull pain and it had slightly greater analgesic effect than electroacupuncture with continuous stimulation.