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PubMed1988

The significance of stapedial reflex test in facial nerve paralysis.

The stapedial reflex of 30 patients with peripheral facial nerve paralysis was compared with the results of facial paralysis scores. The stapedial reflex was measured with an oto-reflex analyser, RS-06A. The stimulation frequencies in the stapedial reflex test were 500, 1,000 and 2,000 Hz for both ipsilateral and contralateral stimulation. The stapedial reflex test at 500 Hz for contralateral stimulation seemed to be useful for evaluating the degree of facial paralysis. With 500 Hz or 1,000 Hz contralateral stimulation, the stapedial reflex test seemed to be useful for predicting the prognosis for facial nerve paralysis. In these stimulations, cases with a positive reflex within 2 weeks showed complete recovery within 12 weeks, and cases with positive reflex within 4 weeks showed recovery within 24 weeks.

Adolescent↗

PubMed1987

Early development of the acoustic reflex.

Acoustic reflex testing was conducted on 2-day-old and on 6-week-old infants to determine how frequently, if at all, the acoustic reflex occurs, if it can be reliably observed, and also to determine what is the mean normal acoustic reflex threshold for pure tones and broad-band noise in these populations. Twenty normal infants were tested in each group. Each infant was considered to be normal by the following criteria: full term, normal pregnancy normal pregnancy and delivery, birth weight greater than 2500 g, 5-min Apgar of 7 or greater, and considered to be not at risk for hearing loss by the absence of any high risk factors. Subjects were tested following feedings. Acoustic reflexes were obtained from subjects with normal tympanograms (+/- 50 mm H2O) for 500, 1,000, 2,000, and 4,000 Hz and broad-band noise stimuli. Behavioral responses were common, requiring quieting pauses in testing and repeated stimulation for habituation of the behavioral component. Acoustic reflexes were observed, and normative reflex threshold data were obtained. The number of reflexes obtained and the mean acoustic reflex thresholds for these age-groups are reported.

Acoustic Impedance Tests↗

PubMedDate not supplied

Effect of stimulus duration on stapedius reflex threshold in electrical stimulation via cochlear implant.

The effect of stimulus duration on the threshold of the contralateral stapedius reflex was investigated in patients supplied with a Vienna cochlear implant (analog stimulation via CI) and compared to results of a normal-hearing reference group in case of acoustic stimulation. Changes in reflex threshold were determined at four frequencies (125, 500, 1,000 and 2,000 Hz in case of electrostimulation and at 500, 1,000, 2,000 and 4,000 Hz for acoustic stimulation) and for five durations (30, 50, 100, 300 and 500 ms). The comparison of the two stimulation modes was accomplished by using the same instrumentation and procedure. Reflex threshold was evaluated according to an objective criterion based on the individual noise distribution of recordings without reflex and by subjective judgement. For both stimulation modes a strong effect of stimulus duration on reflex threshold was observed (p < 0.001). The amount of temporal integration reflected by the threshold difference between 500 and 50 ms was approximately 2-4 dB for electrical stimulation via CI and 6 dB for acoustic stimulation in normal-hearing individuals. In case of electrostimulation, the reflex threshold for stimuli of 30 ms was most often above the limit of uncomfortable loudness sensation; the increase in reflex threshold for acoustic stimulation between 500 and 30 ms was approximately 14 dB. There was no evidence of frequency effect on reflex threshold nor an interaction between frequency and stimulus duration for either stimulation mode.

Adult↗

PubMed2000

Environmental changes in soleus H-reflex excitability in young and elderly subjects.

The purpose of this study was to examine the role of task complexity on soleus H-reflex modulation in young and elderly subjects. Twelve young (mean age = 29.2yrs) and 10 elderly (mean age = 75.1 yrs) apparently healthy individuals were examined under four experimental conditions: (1) eyes open on normal floor surface; (2) eyes open on foam floor surface; (3) eyes closed on normal floor surface; and (4) eyes closed on foam surface. Under each condition, soleus H-reflexes, and background electromyography (EMG) (40 ms window prior to stimulation in both the soleus and the tibialis anterior) were recorded. Postural sway in each condition was also assessed using a Kistler force platform. Results indicated differential reflex modulation between young and elderly subjects. Specifically, young subjects depressed the amplitude of the reflex as task complexity was increased. Elderly subjects, on the other hand, increased the amplitude of the H-reflex when utilizing visual cues, but decreased H-reflex amplitude when vision was occluded. Postural sway in both groups increased as task complexity was increased. There existed a significant difference in the relationship between tibialis anterior activation and soleus H-reflex between the two groups. These results demonstrate differential reflex adjustments between young and elderly subjects as task complexity is increased, and may provide useful information pertaining to postural control in the elderly.

Adult↗

PubMed1994

Modulation of the triceps surae H-reflex with training.

Thirteen neurologically healthy adults were asked to balance on a specially designed balance board. This board allowed rotation in the sagittal plane only. Muscle activity of the triceps surae and tibialis anterior was sampled at 2 kHz and recorded. When the subject was balanced, soleus H-reflexes were elicited in the right leg with a constant-current stimulus pulse. The peak to peak amplitude of the soleus H-reflex served as the perturbation to the subject's balance as well as the dependent variable in question. Subjects performed three blocks (7 H-reflexes/block) of standing control trials with the balance board supported, and seven blocks of balancing trials. Prior to each block, maximal M-waves were recorded to ensure electrode stability across blocks. Results indicated that the subjects were able to significantly reduce (p < .001) the gain the soleus H-reflex while balancing and after the balance training. As a group, the subjects decreased their peak to peak amplitude of the soleus H-reflex by 26.2 percent from the initial standing block to the last balancing block. Moreover, subjects were also able to significantly reduce the gain of their standing control H-reflexes, supporting the notion of longer-term adaptability of the spinal stretch reflex. It is concluded that the progressive reduction in the H-reflex gain with short-term training may represent functional adaptation in the central nervous system.

Adolescent↗

PubMed1995

Acoustic reflex measures at high probe frequency: a phasor diagram approach.

Acoustic reflex measures at high probe frequencies (above 660 Hz) have not been extensively reported in the published literature. Studies of the acoustic reflex at low probe frequencies conflict as to the effect of the reflex on resistance, although all researchers agree that the reflex increases the amount of negative reactance (stiffness). These differences may reflect methodological differences across studies. Lutman and his associates (Lutman and Martin 1979; Lutman et al., 1984) have used phasor diagrams to provide evidence for the effect of the reflex being on reactance, with constant resistance for low probe frequencies (220 and 660 Hz). The present study incorporated the use of this method in order to investigate the effect of the reflex at a 1000 Hz probe frequency in 30 normal ears. Phasor diagrams of probe tip susceptance and conductance values obtained for three stimuli at a 1000 Hz probe frequency were analysed qualitatively. Eighty-two out of a total of 90 phasor diagrams obtained were matched to the constant-resistance stiffness-change model, suggesting that similar effects of the reflex are seen at low and high probe frequencies in most cases. This was noted to be the case for ears that were either stiffness-dominated or at their natural frequency at the 1000 Hz probe. However, the effect of the reflex on mass-dominated systems was less clear and needs further clarification.

Acoustic Stimulation↗

PubMed1989

Temporal integration of acoustic and cutaneous stimuli shown in the blink reflex.

Temporal integration of pairs of brief blink-eliciting acoustic and cutaneous stimuli was investigated to determine if there was integration of stimuli from different modalities. Reflexes elicited by a tone burst or by a brief electrical shock to the supraorbital nerve followed by a second tone burst or shock at short stimulus onset asynchronies (SOAs) were larger and faster than control reflexes elicited by a single stimulus identical to the lead stimulus of the stimulus pairs. Reflex amplitude was augmented at longer SOAs where there was no effect on latency. Temporal integration was evident for all stimulus pairs, showing that it is due, at least in part, to processes that occur outside specific sensory pathways. Heterogeneous stimulus pairs produced greater reflex enhancement than did homogeneous stimulus pairs. This finding was examined further in Experiment 2, which showed that reflex enhancement with pairs of acoustic pulses was unaffected by the frequency of the second stimulus, suggesting that sensory masking was not acting to suppress reflex expression with acoustic pulse pairs. Integration of reflexogenic acoustic stimuli shown in the blink reflex is restricted to shorter intervals than is integration of acoustic stimuli shown by psychophysical procedures, suggesting that the two methods reflect different aspects of stimulus processing. Integration of reflexogenic stimuli may result from summation of activity associated more directly with reflex expression than with perceptual awareness.

Acoustic Stimulation↗

PubMed1990

[A physiological study of the effect of vibration on reflexive control of cats' larynx: the changes in respiratory phase and the role of internal branch of superior laryngeal nerve].

It is generally considered that the vocal cord is finely and reflexively controlled during phonation. In order to investigate the effect of vibratory stimulation of the subglottis on laryngeal reflex, experiments have been performed using cats' larynx under urethane-chloralose general anesthesia. The effect of vibration was estimated by the latency and the area of integrated EMG of the reflex. The glottic closure reflex was induced by electrical stimulation of the internal branch of the superior laryngeal nerve (ISLN) and electromyogram was recorded from contralateral Thyroarytenoid muscle (TA). When ISLN was stimulated, short latency response (early response) and long latency response (late response) in TA was observed. Maximum responses were obtained during the transitional phase, namely, from inspiration to expiration, especially before the denervation of ISLN from the larynx. This phase was tentatively designated as "phase I", being followed by "phase II", the phase prior to "phase I", as "phase III". Vibratory stimulation (100 or 200Hz, 40 microns), applied to the contralateral subglottic portion as a conditioning stimulation, had no effect on early response but enhanced late response, particularly in phase I. After denervation of ISLN, the vibratory effect on late response became phase independent. Furthermore, when the vibratory frequency was elevated from 100Hz to 350Hz at 50Hz interval in phase I, vibration effect was observed in all frequencies investigated. Maximum effect was obtained at 300Hz. However, after denervation of ISLN, this effect was minimized, and no peak observed. The vibratory effects disappeared soon after local anesthesia of the subglottic mucosa. These results suggest that the activity of the mechanoreceptors to vibration in the subglottic mucosa enhances reflexive contraction of the contralateral TA primarily via the recurrent laryngeal nerve and partially via ISLN, both of which are indispensable for reflexive laryngeal control. It is conceivable that early response is one of the primitive reflexes for the protection of the lower airway, and late response is a sort of more evolved reflexes involved in vibration and respiration during phonation.

Animals↗

PubMed1998

A comparison of newborns' NBAS reflex responses using total and individual scores. Neonatal Behavioral Assessment Scale.

The purpose of this study was to compare results found using a total summative score of abnormal reflex responses with the results found using individual reflex scores. The 20 reflexes included as part of the Brazelton Neonatal Behavioral Assessment Scale (NBAS) were assessed on 196 neonates on the 1st and 2nd days postnatally. Differences due to of type of delivery, birth weight, whether their mothers were insulin-dependent diabetics or nondiabetics, and day of testing were assessed by using analysis of variance. The key results were that all effects found using the total reflex score were replicated with individual reflex scores and that individual reflex scores also revealed effects not shown using the total score. It was concluded that the individual reflex scores, rather than the total score, should be used when evaluating newborn reflex performance.

Adult↗

PubMed1978

Muscle responses and monosynaptic reflexes in falling monkey. Role of the vestibular system.

The free fall has been used in our laboratory as a way to test vestibular function in baboons in order to quantify vestibular compensation in the hemilabyrinthectomized animal. This study presents only those results that concern the contribution of the vestibular system to muscle responses due to sudden fall. EMG activity was recorded from the fully conscious animal using chronic electrodes implanted in various muscles. Spinal monosynaptic reflexes (Hoffmann's and tendon reflexes) were studied in the soleus muscle. Baboons were seated in a special chair suspended from an electromagnet and unexpectedly dropped 90 cm. Experiments were performed in normal, unilateral and bilateral vestibular neurectomized baboons. 1. In normal baboons, results showed a first short-latency response in all tested muscles, followed by a second peak of EMG activity in these muscles. Comparison with data from bilateral vestibular neurectomized baboons demonstrates that normal vestibular function is essential for the appearance of the first peak; the second peak rapidly disappears in our experimental situation where the animal's fall is mechanically braked and interrupted, so the animal does not have to make the postural adjustments necessary for landing, It is suggested that the first peak is concerned with the automatic and reflex control of landing, the second with the voluntary breaking of landing. 2. The modulation of monosynaptic spinal reflexes is closely related to the EMG response in soleus muscle. Facilitation of the H-reflex begins just prior to the onset of the EMG activity and continues as long as the baboon is falling. The T-reflex modulation presents a similar time course except in its early phase where it is depressed. Decrease in T and increase in H-reflexes suggest that the EMG response is most likely due to direct activation of alpha-motoneurons and not by means of the gamma-loop. 3. In unilateral vestibular neurectomized baboons, EMG and reflexological data show the classical asymmetry characterized by a strong decrease of the responses on the side of the lesion, and by a pronounced increase on the contralateral side. It is concluded that this represents the imbalance between the resting discharge of the vestibular neurons, and discloses the influence of labyrinthine afferences at the spinal level. We suggest consequently the use of EMG responses and modulation of spinal reflexes to fall in order to quantify vestibular compensation.

Animals↗

PubMed2000

Stretch reflexes in the rectus abdominis muscle in man.

The spinal reflex circuitry of the rectus abdominis (RA) muscle in man was investigated by the application of a mechanical tap to the muscle. Electromyographic recordings were made in ten healthy subjects, performing a series of manoeuvres, using pairs of surface electrodes placed bilaterally. The reflex responses elicited largely depended on the amount of tonic (postural) activity of the trunk. When standing in the upright position, no reflex activity was recorded in response to the tap. Reflex activity due to mechanical tap was readily recorded when the muscle became tonically active. Moderate, backward trunk extension introduced short-latency reflexes at 18.8 +/- 1.9 ms (mean +/- S.D.) ipsilaterally and 20.8 +/- 1.8 ms contralaterally. Excitatory reflex activity of longer latency was also recorded contralaterally in all subjects (latency 45.1 +/- 4.3 ms) and ipsilaterally in five of the ten subjects (latency 47.2 +/- 2.6 ms). Vibration of the tapped muscle produced a reduction in the amplitude of the early reflex responses, whilst increasing the amplitude of the late responses. Moreover, the early reflexes were facilitated by the Jendrassik manoeuvre. Such observations are consistent with the early responses being mediated, at least partly, monosynaptically, and the late responses being of polysynaptic nature. This implies that muscle spindle afferents from rectus abdominis monosynaptically activate motoneurones contralaterally.

Adult↗

PubMed2000

Kainic acid lesions to the lateral tegmental field of medulla: effects on cough, expiration and aspiration reflexes in anesthetized cats.

We have tested the hypothesis that neurons of both the ventral reticular nucleus and the adjacent parts of the lateral tegmental field (LTF) may be important for the production of motor programs associated with cough, expiration and aspiration reflexes. Our studies were conducted on non-decerebrate, spontaneously breathing cats under pentobarbitone anesthesia. Dysfunction of the medullary LTF region above the obex, produced by uni- or bilateral injections of kainic acid (a neurotoxin), regularly abolished the cough reflex evoked by mechanical stimulation of both the tracheobronchial and laryngeal regions and in most cases also the expiration reflex induced from the glottal area. However, some electrical activity still occurred in the neurogram of the recurrent laryngeal nerve during probing the laryngeal and glottal regions. Interestingly, the aspiration reflex elicited from the nasopharynx regularly persisted, although with lower intensity after the LTF lesion. Nevertheless, successive midcollicular decerebration performed in four cats also abolished the aspiration reflex. These experiments demonstrate the importance of medullary LTF neurons for the normal occurrence of cough and expiration reflexes. One possible explanation for the elimination of these expulsive processes is that the blockade of the LTF neurons may remove an important source of a facilitatory input to the brainstem circuitries that mediate cough and expiration reflexes. In addition, the potential importance of the mesencephalic reticular formation for the occurrence of the aspiration reflex and the role of the LTF in modulating both the eupnoeic breathing and the blood pressure are also discussed.

Anesthesia↗

PubMedDate not supplied

The effects of electrical nerve stimulation of the lower extremity on H-reflex and F-wave parameters.

The main purpose of this study was to investigate the effects of electrical nerve stimulation on alpha motoneurons excitability. The electrophysiological parameters of H-reflex and F-wave were assessed for this object. These experiments was performed on ten non-athletic healthy men without neurologic disorders with mean age 25.6 years (SD 4.4) and three spastic hemiplegic patients with mean age 65.33 years (SD 6.32). In the experimental protocol, electrical stimulation (TENS) applied on common peroneal nerve with frequency 99 Hz and duration 0.25 ms for 30 minutes. H-reflex and F-wave of the soleus muscle were recorded in three stages sequenced immediately, 5 minutes and 10 minutes later on. The parameters such as amplitudes and latencies of H-reflex and F-wave were compared with the data of first record before stimulation. Finally, after 30 minutes application of TENS the following results were obtained: 1. The mean peak to peak amplitude of H-reflexes and F-waves were significantly decreased after application of TENS in normal subjects. (P < 0.05) 2. H/M ratios and F/M ratios were significantly decreased after application of TENS in normal subjects. (P < 0.05) 3. The mean latency of H-reflexes and F-waves were significantly increased after application of TENS in normal subjects. (P < 0.05) 4. In spastic patients, the mean peak to peak amplitude of H-reflexes and F-waves, H/M and F/M ratios were significantly decreased and the mean latencies of H-reflexes and F-waves were significantly increased after application of TENS. The reduction of amplitude of H-reflexes and F-waves, H/M and F/M ratios demonstrated reduction of spasticity in patients group. The above-mentioned parameters are parts of electrophysiological indicators about assessment of spasticity.

Adult↗

PubMed1992

[The development of I. P. Pavlov's conditioned reflex theory].

This paper deals with the theory of Ivan Petrovich Pavlov (1849-1936), a Russian physiologist who presented for the first time the systematic theory of the function of the brain that controls the whole behavior of animals, i.e. higher nervous activity through experimental studies. This paper, principally based on Lectures on Conditioned Reflexes (1928), investigates the development of conditioned reflex theory from its beginning by dividing it into three periods. First, during the period from 1898 to 1906, the fundamental concept of conditioned reflex was established and the study of conditioned reflex became an independent discipline. From 1907 to 1916, the second period, Pavlov theorized on higher nervous activity on the basis of extensive data from his laboratory experiments of conditioned reflex. And Pavlov complemented conditioned reflex theory, during the third period from 1916 to 1928, and extended the boundaries of it through applications of conditioned reflex theory to psychopathology and typology. The study contributes to the understanding that conditioned reflex theory was historically developed, and not presented as a complete form from the beginning, and that Pavlov intended to study the higher nervous activity through the method of neurophysiology.

Animals↗

PubMed1975

Ipsilateral acoustic reflex stimulation in normal and sensorineural impaired ears: a preliminary report.

Ipsilateral acoustic reflex thresholds were measured at 1,000 Hz and 2,000 Hz in 38 subjects with normal hearing and in 107 subjects with a symmetrical sensorineural hearing loss. Acoustic reflex thresholds were approximately six dB better for ipsilateral vs. contralateral stimuli for both subject groups. High ipsilateral reflex thresholds were associated with larger static compliance values in the sensorineural hearing impaired subjects. Reversed reflexes (increasing compliance with muscle contraction) were observed for ipsilateral stimulation in five per cent (two) of the normal hearing subjects, and 23 percent (25) of the sensorineural hearing impaired subjects. The number of reversed reflexes was greater for subjects with higher hearing thresholds and higher ipsilateral acoustic reflex thresholds. The results suggest that quantitative use of the ipsilateral acoustic reflex requires additional research. At present it seems prudent to use ipsilateral acoustic reflex measurements as a qualitative rather than a quantitative tool, e.g. in confirming the status of one middle ear when the other has a conductive hearing loss. However, even this limited role has a considerable clinical potential.

Acoustic Stimulation↗

PubMed2000

[Role of nitric oxide in the reflex of raising biliary pressure].

Raising the biliary tract pressure from the baseline to 4 kPa significantly decreases arterial blood pressure and myoelectric activity of sphincter of Oddi (SO) (bile duct-arterial blood pressure reflex), which is sometimes associated with the disappearance of phasic myoelectric activity of SO (bile duct-SO reflex). Thirty-two rabbits were used to investigate the role of nitric oxide (NO) in these reflexes. On the base of increased myoelectric activity and arterial blood pressure by intravenous drip of 4 microgram/(kg.min) noradrenaline, raising the biliary tract pressure from the baseline to 4 kPa significantly decreased arterial blood pressure and myoelectric activity of SO. On the base of increased myoelectric activity and arterial blood pressure by intravenous injection of 10 mg/kg L-NNA, the bile duct-arterial blood pressure reflex disappeared in all the rabbits, but the bile duct-SO reflex disappeared only in a population of (3/8) and obviously decreased in the remaining ones (5/8) during raising biliary pressure from the baseline to 4 kPa. The bile duct-SO reflex after preceding local perfusion of L-NNA was similar to that after preceding intravenous injection of L-NNA, but bile duct-arterial blood pressure reflex still appeared. These findings suggest that both of these two reflexes are caused by the tension stimulation to the receptive area of the biliary tract, and may be mediated by NO.

Animals↗

PubMed2002

Spinal sensorimotor transformation: relation between cutaneous somatotopy and a reflex network.

The projection of primary afferents onto spinal interneurons constitutes the first step in sensorimotor transformations performed by spinal reflex systems. Despite extensive studies on spinal somatotopy, uncertainties remain concerning the extent and significance of representational overlap and relation to spinal reflex circuits. To address these issues, the cutaneous projection from the hindpaw and its relation to the topography of lamina V neurons encoding withdrawal reflex strength ("reflex encoders") was studied in rats. Thin and coarse primary afferent terminations in laminas II and III-IV, respectively, were mapped by wheat germ agglutinin-horseradish peroxidase and choleragenoid tracing. The functional weights of these projections were characterized by mapping nociceptive and tactile field potentials and compared with the topography of reflex encoders. Both anatomical and physiological data indicate that thin and coarse skin afferent input is spatially congruent in the horizontal plane. The representation of the hindpaw in the spinal cord was found to be intricate, with a high degree of convergence between the projections from different skin sites. "Somatotopic disruptions" such as the representation of central pads medial to that of the digits were common. The weight distribution of the cutaneous convergence patterns in laminas III-IV was similar to that of lamina V reflex encoders. This suggests that the cutaneous convergence and features such as somatotopic disruptions have specific relations to the sensorimotor transformations performed by reflex interneurons in the deep dorsal horn. Hence, the spinal somatotopic map may be better understood in light of the topography of such reflex systems.

Action Potentials↗

PubMed2002

[Reflex sympathetic dystrophy of childhood: one case].

INTRODUCTION: Reflex sympathetic dystrophy (Complex Regional Pain Syndrome type 1) is little known by dermatologists. We report a pediatric case of reflex sympathetic dystrophy with predominant cutaneous involvement. CASE REPORT: A 10 year-old girl presented a warm, painful and relapsing right hand edema for seven months (three outbreaks). The hand was cyanotic, pigmented and painful. Routine blood tests were normal. Radiography and radionuclide bone scan were consistent with stage 1 reflex sympathetic dystrophy. Physiotherapy led to dramatic improvement. DISCUSSION: Reflex sympathetic dystrophy is known since the XVIIIth century. In the last decade, progress in radiology and bone scan have provided elements for understanding the physiopathology of the disease. Microvascular abnormalities under the control of sympathetic nervous system are characteristic of different stages of reflex sympathetic dystrophy. Recently, neurovascular system experiments showed that sympathetic reflex tonus changes may be controlled by the central nervous system. Dermatologic changes of reflex sympathetic dystrophy are well known: edema and erythema in first stage, cyanosis in second stage, sclerosis and atrophia in third stage, but pediatric cases are rarely reported. CONCLUSION: Reflex sympathetic dystrophy is a complex disease, however its physiopathology is now understood. The clinical presentation can be atypical and the dermatologist may be the first to be consulted.

Child↗