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PubMedDate not supplied

[Effect of a dominant focus created in the center of the wink reflex on the local defense reflex in the rabbit].

The paper deals with conjugated inhibition of rabbit's defensive limb reflex at formation of a dominant focus in the center of the eye-lid reflex. In the initial period of dominant focus formation, when the dominant comes through the stage of summation reflex, electrocutaneous limb stimulation induced, along with successive summation, temporary inhibition of the forming dominant focus. The dominant focus formed in the eye-lid center did not induce conjugated inhibition of the limb defensive reflex. In the study of the influence of the eye-lid reflex on the motor defensive one it was found that formation of temporary connection of summation reflex type, led to circulatory interaction between the centers.

Animals↗
PubMed1981

[Reflex effects of cough reflex on the tracheobronchial vascular tone (author's transl)].

In a previous paper, it was shown that the cough reflex was accompanied by a slight fall of systemic arterial pressure, tracheal constriction and tracheal vasodilation. In the present study, tracheobronchial muscular and vascular tones during the cough reflex were investigated using the blood perfused canine tracheal and bronchial preparations in situ. The cough reflex was elicited with electrical stimulation of the membraneous wall mucosa of the upper trachea. In the blood perfused tracheal preparation, a close intraarterial injection of atropine or bilateral vagotomy inhibited the tracheoconstriction but had no effect on the tracheal vasodilation during the cough reflex. In the blood perfused bronchial preparation, electrical stimulation of the upper tracheal mucosa induced bronchial constriction but not bronchial vasodilation. Lung inflation with air resulted in a bronchial vasodilation and which persisted even after a close intraarterial infusion of atropine and benzonatate and after bilateral vagotomy. These findings indicate that the tracheobronchial constriction response are primary reflex effects following coughing and the tracheobronchial vasodilation responses are secondary reflex effects induced by increase in internal pressure of the respiratory tract.

Animals↗
PubMed1994

Excitability of the soleus motoneuron pool revealed by the developmental slope of the H-reflex as reflex gain.

The excitability of a motoneuron (MN) pool was evaluated by the developmental slope of H-reflexes (Hslp) evoked at a range of a stimulus intensity less than the threshold of an M-response. The Hslp has been regarded as the "reflex gain", which is the changing rate in MN excitability as a function of the increase of Ia input to an MN pool. In a comparison of two parameters used in the H-reflex technique, such as the ratio of the maximal H-reflex to the maximal M-response and the ratio of the threshold of an H-reflex to that of an M-response, the Hslp was predicted to be a reasonable parameter to evaluate motoneuronal excitability, because the Hslp is free from the effect of any collision between the H-reflex discharge and the antidromic volley drived from the occurrence of an M-response within the alpha-efferents, and the Hslp can estimate the recruitment properties of a whole MN pool. The Hslp was alleviated during dorsi-flexion and steepened during plantar-flexion, according to the inhibitory or facilitatory synaptic modifications onto soleus MNs. The developmental slope of an M-response (Mslp), which shows the recruitment property of axons of soleus MNs, was alleviated especially in plantar-flexion. In order to exclude the peripheral neuromuscular factors in evaluating substantial MN excitability, the Hslp/Mslp is proposed as a more effective parameter than the Hslp.

Adolescent↗
PubMed1993

Development of the stretch reflex in the newborn: reciprocal excitation and reflex irradiation.

The stretch reflex is a spinal cord pathway between a muscle's stretch receptors and its own motor units. This reflex is thought to play an important role in normal motor function, because it is unique as a monosynaptic pathway, and because its hyperactivity is a hallmark of many motor disorders. We previously reported a difference in the stretch reflexes in healthy newborn infants and nonambulatory individuals with cerebral palsy (CP): these reflexes are characterized by responses from the stretched muscle and from the reciprocal or antagonist muscle. We proposed the existence of a functional spinal cord pathway that connects both agonist and antagonist muscles at a single joint. We hypothesized that this "reciprocal excitation" is a functional pathway of all newborn infants, which during the normal course of development of motor skills in infants is eliminated. If the CNS is damaged at birth, as in CP, the pathway of reciprocal excitation endures and is reinforced. In the current study of newborns, we recorded stretch reflex responses from all major muscle groups of the lower limb. This "irradiation of reflexes" is a normal phenomenon of the newborn CNS. This pathway becomes suppressed during normal maturation and control of coordinated limb movements.

Achilles Tendon↗
PubMed1996

The role of the spinal cord as a reflex center for the somatically induced reflex responses of splenic sympathetic and natural killer cell activity in anesthetized rats.

Somatic afferent regulation of splenic natural killer (NK) cell activity by hindpaw pinching has been proven, in anesthetized rats, to be a reflex response whose reflex center is in the brain and efferent arc is a splenic sympathetic nerve. Using central nervous system (CNS)-intact and acutely spinalized anesthetized rats, the present study aimed to examine the possibility of whether afferent stimulation (pinching) of the skin over the abdominal segments could influence cytotoxic activity of splenic NK cells and splenic sympathetic nerve activity at the spinal segmental level. In CNS-intact rats, pinching stimulation of the skin of the abdomen with surgical clamps for 30 min did not significantly change cytotoxic activity of splenic NK cells although splenic sympathetic nerve activity increased slightly. In acutely spinalized rats the same stimulation reduced cytotoxic activity of splenic NK cells and was accompanied by an intense reflex increase in splenic sympathetic nerve activity. It is concluded that the spinal cord is capable of producing propriospinally the reflex suppression of cytotoxic activity of splenic NK cells via reflex activation of the splenic sympathetic efferent nerve following stimulation to the abdominal segments whose afferent information enters the spinal cord at the same segments or segments overlapping the splenic sympathetic outflow. A possible mechanism of inhibition of this spinal reflex by inhibitory descending pathways is discussed.

Animals↗
PubMed1997

Olfactory-corporeal reflex: description of a new reflex and its role in the erectile process.

OBJECTIVE: The dog approaches the bitch and smells the vulva. The relationship which seems to exist between a special smell in the bitch and sexual arousal in the male dog was investigated. METHODS: 12 male dogs and 25 bitches were studied. The bitches were divided into five equal groups, each representing 1 of the 5 phases of the estrous cycle. A vaginal swab that soaked in the bitches' vaginal secretions was divided into two pieces: one was sent for estradiol and progesterone determination, and the other was smelt by the male dog. The responses of the intracorporeal pressure (IP) and the electromyographic activity of the bulbo- and ischiocavernosus (BC, IC) muscles of the male dog to the smelling of bitch's vaginal odor were assessed. The pressure response was also determined 10 min and 1 h after either the nasal mucosa or the corporeal tissue was anesthetized. RESULTS: Elevated IP was recorded in 12 of 12, 10 of 12 and 8 of 12 dogs smelling vaginal swabs of bitches in metestrus (p < 0.001), estrus (p < 0.001), and diestrus (p < 0.01), respectively. No pressure response occurred when the vaginal swab was smelt while the nasal mucosa or the corporeal tissue was anesthetized. The BC and IC muscles exhibited no response to smelling of the vaginal swab of bitches in any phase of the estrous cycle. The results were reproducible. CONCLUSIONS: The study showed that the IP increased with smelling of vaginal secretions containing high progesterone levels, whereas estradiol-17 beta did not effect IP elevations. The higher the progesterone level, the greater the IP. The increased IP is not due to BC and IC muscle contraction. It is postulated that a reflex relationship exists between IP elevation and olfactory stimulation. This reflex response was reproducible and was not evoked when the two arms of the reflex were anesthetized. We call this reflex 'olfactory-corporeal reflex'. This reflex seems to prime the male dog for sexual intercourse.

Animals↗
PubMed2001

Masseter reflex and blink reflex abnormalities in Chiari II malformation.

Masseter reflex and blink reflex were evaluated in 64 patients with a myelomeningocele and Chiari II malformation. In 46 patients, no brainstem signs or symptoms were present. Brainstem dysfunction related to Chiari II malformation occurred in 18 patients. The masseter reflex was more frequently abnormal in the symptomatic than asymptomatic patients (P = 0.02). Although the blink reflex was similarly affected in the two groups of patients (P > 0.1), it was very sensitive, being abnormal in 83% of symptomatic and 65% of asymptomatic patients. Concomitant abnormality of masseter reflex and the late contralateral blink reflex component (R2c) was almost exclusively found in symptomatic patients and reached the highest significance in separating the two groups (P = 0.002).

Adolescent↗
PubMed1993

Blink reflex and the masseter inhibitory reflex in patients with dystonia.

The excitatory and inhibitory interneuronal pathways in the brainstem are tested by examining the blink reflex and the masseter inhibitory reflex, respectively. We studied the R2 component of the blink reflex and the SP2 component of the masseter inhibitory reflex and their recovery cycle in 56 patients with various forms of dystonia. In patients with cranial, cervical, and generalized dystonia, but not in patients with extracranial segmental dystonia, the recovery cycle of both reflexes was enhanced. The recovery cycle of R2 and SP2 can demonstrate subclinical changes in excitability of brainstem interneurons. The degree of enhancement of the recovery cycles did not correlate, however, with the severity of clinical facial muscle impairment. In addition, the recovery cycles correlated positively with each other, showing that excitatory as well as inhibitory interneuronal pathways in the brainstem are perturbed in dystonia. Study of the trigemino-facial and trigemino-trigeminal reflexes provides an objective tool for assessing functional abnormalities in dystonia.

Adult↗
PubMed2002

Activation of mu-opioid receptors in rat ventrolateral medulla selectively blocks baroreceptor reflexes while activation of delta opioid receptors blocks somato-sympathetic reflexes.

The effects of activation of mu and delta-opioid receptors in the rostral ventrolateral medulla (RVLM) on somato-sympathetic, baroreceptor and chemoreceptor reflexes, as well as respiratory rhythmicity in sympathetic nerves, were examined in urethane anaesthetized (1.1-1.2 g/kg) and artificially ventilated Sprague-Dawley rats. Microinjection of the delta-opioid receptor agonist [D-Pen(2,5)]-enkephalin (DPDPE; 8 mM, 50 nl) bilaterally into the RVLM potently inhibited the post-inspiratory-related burst discharges of lumbar sympathetic nerve activity (LSNA) but had only limited effects on splanchnic sympathetic nerve activity (SSNA) and phrenic nerve discharge. Injection of DPDPE into the RVLM strongly attenuated the somato-sympathetic reflex (approximately 50-80%) evoked in the lumbar sympathetic nerve and splanchnic sympathetic nerve by tibial nerve stimulation but had no effect on baroreceptor reflexes and chemoreceptor reflexes evoked by aortic nerve stimulation and brief hypoxia, respectively. Injection of the mu-opioid receptor agonist, [D-Ala(2),N-Me-Phe(4),Gly-ol(5)]-enkephalin (DAMGO; 4 mM, 50 nl), also elicited a greater inhibition of LSNA than SSNA accompanied by an abolition of phrenic nerve discharge. Injection of DAMGO inhibited the baroreceptor reflex without significant effect on either the somato-sympathetic or the chemoreceptor reflexes. We propose that opioid peptides diminish specific excitatory and inhibitory inputs to the presympathetic neurons in RVLM via distinct presynaptic receptor subclasses.

Action Potentials↗
PubMed1988

Stabilizing gaze reflexes in the pigeon (Columba livia). II. Vestibulo-ocular (VOR) and vestibulo-collic (closed-loop VCR) reflexes.

The vestibulo-ocular reflex (VOR) and the closed-loop vestibulo-collic reflex (CL-VCR) were investigated in the pigeon. The animals, placed either in the fixed-head condition (VOR) or in the free-head condition (CL-VCR) were rotated in darkness (vestibular responses) or in the presence of visual surroundings (visuo-vestibular responses). The linear range of the reflexes were determined both in the frequency and in the velocity domains. Results show that: 1. Pigeons develop a strong VOR, which presents the same asymmetry observed with the OKN, the gain being higher when the slow-phase occurs in the T-N direction. This asymmetry persists in the light (VOR + OKN). In the free-head condition, both the eye and the head display a synchronized nystagmus whose effects are additive. The head reflex (CL-VCR) contributes about 80% of the gaze stabilization. 2. In the medium-low frequency range, the head response (CL-VCR) has a lower gain than the VOR (head-fixed), but the gain of both reflexes increases with frequency, up to about 1 at 0.6-1 Hz. The gaze response (eye + head) presents an optimal gain above 0.06 Hz. The phase lead is higher for the VOR than for the CL-VCR (40 degrees and 32 degrees respectively at 0.03 Hz), but both phases also become nul around 1 Hz. The time constants are 6.5 s for the VOR, 8.5 s for the CL-VCR and 9.6 s for the gaze response (VOR + CL-VCR). 3. While the VOR gain shows a saturation at peak stimulation velocities (PV) higher than 20 degrees/s (at 0.3 Hz), the CL-VCR gain is linear at least up to 60 degrees/s (the highest PV used). However, the phase lead declines when the PV is greater than 20 degrees/s, both for the VOR and the CL-VCR. 4. When the vestibular stimulation is delivered in the light (visuo-vestibular stimulation), there is no phase shift. The VOR gain (fixed-head) is optimal and linear over the entire frequency range, but it saturates for PV higher than 40 degrees/s. In the free-head condition, while the gaze gain is linear and close to 1 in both the frequency and the velocity domains, the head response gain (CL-VCR) remains lower especially in the low frequency and in the low velocity ranges.

Animals↗
PubMed1996

Reflex sympathetic dystrophy: skin blood flow, sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy.

To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, skin resistance and skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four patients were treated with unilateral surgical sympathectomy and pain and vascular changes were documented in follow-up investigations. (1) After acclimatization in cold environment (< or = 18 degrees C) blood flow and skin temperature were considerably lower on the affected side in 10 patients. No additional vasoconstrictor reflexes could be elicited. (2) After acclimatization in warm environment (22-24 degrees C) blood flow and skin temperature demonstrated no side differences in all cases. Vasoconstrictor responses were the same on both sides. (3) After sympathectomy vasoconstrictor reflexes were absent. Skin resistance was considerably higher on the affected side. In the first 4 weeks the affected hand was warmer and blood flow was higher compared with the healthy side. Thereafter, skin temperature and perfusion slowly decreased and the affected hand turned from warm to cold. Very regular high amplitude vasomotion waves occurred unilaterally. There were no signs of reinnervation. Two patients had long-term pain relief. We conclude as follows. (1) Side differences in skin temperature and blood flow are no static descriptors in RSD. They are dynamic values depending critically on environmental temperature. Therefore, they have to be interpreted with care when defining reliable diagnostic criteria. (2) Vascular disturbances in RSD are not due to constant overactivity of sympathetic vasoconstrictor neurons. Changes in vascular sensitivity to cold temperature and circulating catecholamines may be responsible for vascular abnormalities. Alternatively, RSD may be associated with an abnormal (side different) reflex pattern of sympathetic vasoconstrictor neurons due to thermoregulatory and emotional stimuli generated in the central nervous system. (3) After sympathectomy, denervation supersensitivity of blood vessels and intense vasomotion may be associated with recurrence of pain in some patients.

Adult↗
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↗
PubMed2003

Role of positive anorectal feedback in rectal evacuation: the concept of a second defecation reflex: the anorectal reflex.

BACKGROUND/OBJECTIVE: The present study investigated the hypothesis that rectal contraction is maintained by positive anorectal feedback elicited by continuous passage of stools through the rectal neck (anal canal), and that cessation of stool passage aborts rectal contraction. METHODS: Anal and rectal pressures were measured in 18 healthy volunteers (mean age = 38.6 years; 10 men, 8 women) during evacuation of saline infused into the rectum. Residual fluid volume was calculated. The test was repeated after separate application of lidocaine or bland gel to the rectal neck. RESULTS: On evacuation, fluid emanated from the rectal neck in continuous flow with no, or mild, straining. No residual saline was collected from 16 of 18 participants. After anal anesthetization, evacuation occurred in gushes induced with excessive straining; residual fluid was huge. Repetition of the test 2 hours after anesthetization produced the same results as before anesthetization. Bland gel applied to the rectal neck yielded results similar to those before gel application. CONCLUSION: Rectal contraction at defecation is suggested to be maintained by positive anorectal feedback evoked by continuous passage of stool through the rectal neck. This feedback appears to be affected through an anorectal excitatory reflex (ARR), which produces rectal contraction upon stimulation of anal stretch receptors. Abortion of this reflex by anal anesthetization seems to result in failure of the rectum to contract and in excessive straining to achieve rectal evacuation. ARR thus is suggested to be a second defecation reflex necessary to continue defecation, whereas the rectoanal inhibitory reflex is the primary reflex. The role of the ARR in pathogenesis of constipation and its utility in spinal cord injury need to be investigated.

Adult↗
PubMed1990

H-reflex recovery curve and reciprocal inhibition of H-reflex in different kinds of dystonia.

We studied the H-reflex recovery curve and reciprocal inhibition of the H-reflex bilaterally in the upper limb of 5 patients with generalized dystonia, 5 patients with blepharospasm, 10 patients with spasmodic torticollis, and 14 patients with writer's cramp. We compared the results with those obtained from a group of healthy volunteers. The recovery curve of the H-reflex was normal in patients with writer's cramp or blepharospasm, but showed an increase of the physiologic recovery at a 200 msec delay in patients with spasmodic torticollis or generalized dystonia. Reciprocal inhibition of the H-reflex showed a decrease in the amount of inhibition in all the patient groups and a facilitation of the H-reflex during the 3rd period of inhibition in the patients with spasmodic torticollis or generalized dystonia.

Adult↗
PubMed2001

Effect of pelvic floor muscle contraction on vesical and rectal function with identification of puborectalis-rectovesical inhibitory reflex and levator-rectovesical excitatory reflex.

The effects of pelvic floor muscle contraction on rectal and vesical function were studied in 19 healthy volunteers with the aim of shedding light on some of the hitherto vague aspects of the mechanisms involved in micturition and defecation and their disorders. Rectal and vesical pressures were recorded during puborectalis (PR) and levator ani (LA) muscle stimulation with the rectum or urinary bladder empty and full. Muscle stimulation was effected by needle EMG electrode. The pressure responses to stimulation of the PR and LA muscles were also recorded with these muscles and the rectum and urinary bladder individually anesthetized in 12 of the 19 subjects. The test was repeated using saline instead of xylocaine. PR and LA muscle stimulation produced no pressure response in the empty rectum or bladder. Upon rectal balloon distension with a mean of 156.6+/-34.2 ml of carbon dioxide the mean rectal pressure was 64.6+/-18.7 cm H2O, the subject felt the urge to evacuate and the balloon was expelled to the exterior. On PR muscle stimulation at rectal distension with the above volume, the subject did not feel the urge to evacuate, the rectal pressure was 8.2+/-1.6 cm H2O and the balloon was not expelled. Upon LA stimulation at the same volume, the urge persisted, the rectal pressure was higher and the balloon was expelled. Vesical filling with a mean of 378.2+/-23.6 ml of saline initiated the urge to urinate and elevated the vesical pressure. PR muscle stimulation at this volume aborted the urge and pressure elevation, while LA stimulation caused more elevation of the vesical pressure and spontaneous micturition. Bladder filling with a mean of 423.6+/-38.2 ml produced high vesical pressure and spontaneous urination, both of which were prevented by PR muscle stimulation but not by LA muscle stimulation. Stimulation of the PR and LA muscles during individual anesthetization of the rectum, bladder or PR and LA muscles resulted in no significant rectal or vesical pressure changes. Repetition of the test using saline instead of xylocaine resulted in rectal and vesical pressure responses similar to those without the use of saline. In conclusion, the decline in rectal and vesical responses upon PR muscle contraction indicates a reflex relationship which we term 'puborectalis rectovesical inhibitory reflex'. This reflex is suggested to abort the urge to defecate or urinate. In contrast, LA muscle contraction produced rectal and vesical pressure elevation which is suggested to be mediated through the 'levator rectovesical excitatory reflex'. 'This reflex is probably evoked to promote rectal and vesical evacuation.

Adolescent↗
PubMed1995

Vagino-levator reflex: description of a reflex and its role in sexual performance.

A new reflex, termed the 'vagino-levator reflex', was studied in 17 healthy women (mean age 36.6 years). The vagina was distended with up to 300 ml air in a condom tied to a catheter, and the levator ani response was determined by means of needle electrode introduced into the muscle. The test was repeated after anesthetizing the vagina and the levator muscle, respectively. The levator EMG activity rose when the vagina was distended; the amplitude and duration of activity increased in parallel with vaginal distension. The levator response did not occur after successive repetition of vaginal distension due probably to levator muscle fatigue; nor did it occur after anesthetizing the vagina or the levator muscle. The mean latency of the reflex was 39.5 ms. The vagino-levator reflex seems to play a role in the sexual act. Levator contraction upon penile thrusting leads to genital responses that could facilitate sexual performance. These responses comprise widening of the vaginal introitus, vaginal elongation and ballooning of the upper vagina as well as uterine elevation. Vagino-levator reflex dysfunction may result in disorders of sexual act.

Adult↗