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PubMed1988

Medullary substrates mediating antinociception produced by electrical stimulation of the vagus.

Electrical stimulation of afferents of the right cervical vagus inhibited the tail-flick reflex elicited by noxious heat in barbiturate-anesthetized rats. This inhibitory effect was eliminated in rats receiving local anesthetic blockade of either the nucleus tractus solitarii (NTS), the lateral reticular nuclei, the nucleus raphe magnus-medullary reticular formation, or nucleus raphe obscurus regions of the medulla. Similarly, the vasodepressor and bradycardic effects of vagal stimulation were either attenuated or eliminated by local anesthetic blockade of these regions. Microinjection of the non-specific glutamate antagonist gamma-D-glutamylglycine (DGG) into the NTS region also eliminated vagally evoked inhibition of the tail-flick reflex, hypotension, and bradycardia. Conversely, microinjection of glutamate into the NTS region resulted in inhibition of the tail-flick reflex, hypotension, and bradycardia. These findings with DGG and glutamate are consistent with the view that glutamate serves as a neurotransmitter of the primary vagal afferents mediating these antinociceptive and cardiovascular responses. These results are discussed in terms of vagal afferent influences on somatosensory, somatomotor, and cardiovascular function.

Afferent Pathways↗
PubMed1996

Proximal and segmental motor nerve conduction in the sciatic nerve produced by percutaneous high voltage electrical stimulation.

Percutaneous high voltage electrical stimulation was applied to the proximal sciatic nerve at the hip in 18 normal subjects to evaluate motor conduction in the proximal sciatic nerve, and short-segment stimulation of the sciatic and posterior tibial nerves was given in 6 normal subjects. Compound muscle action potentials (CMAPs) were recorded from the abductor hallucis (AH) and extensor digitorum brevis (EDB) muscles. Supramaximal stimulation was easily obtained at the proximal sciatic nerve and all the sites in the short-segment stimulation. The motor nerve conduction velocity of the sciatic nerve between the hip and the popliteal fossa was 49.2 +/- 4.24 m/sec in the tibial division and 54.1 +/- 6.48 m/sec in the peroneal division. The respective peak-to-peak amplitude and negative-peak areas of the CMAPs at the hip were reduced to 86.8 +/- 5.65% and 97.3 +/- 5.36% for the tibial division, and 93.4 +/- 7.06% and 96.8 +/- 5.09% for the peroneal division as compared to the values for the popliteal fossa. The negative-peak duration of the CMAPs at the hip point were increased to 109.2 +/- 7.2% for the tibial nerve and 107.1 +/- 5.68% for the peroneal nerve as compared with the duration at the popliteal fossa. This method is non-invasive and useful for evaluating motor nerve conduction in the lower limb.

Adult↗
PubMed1985

Evidence for purinergic transmission in mouse bladder and for modulation of responses to electrical stimulation by 5-hydroxytryptamine.

Electrical stimulation (ES) contracted superfused mouse bladder, and 10(-7) M tetrodotoxin (TTX) abolished the twitches without impairing responses to acetylcholine (ACh) or beta,gamma-methylene ATP. ES acted largely through nerves which were not cholinergic, adrenergic or histaminergic. They may be purinergic because the bladder was contracted by stable analogues of ATP, and after desensitisation by a high concentration of alpha,beta-methylene ATP the response to ES was selectively reduced. 5-Hydroxytryptamine (5-HT) at 0.03-3 X 10(-6) M and tetraethylammonium (TEA) at 0.1-10 X 10(-3) M potentiated responses to ES, on average by 64% and 182%. Pempidine had no effect on responses to ES. The action of TEA was different from that of 5-HT; potentiation of responses was greater than could be produced by 5-HT, and whereas 5-HT did not increase responses to ACh, TEA markedly increased twitch tensions. The mode of action of 5-HT is not clear.

Adenosine Triphosphate↗
PubMed1978

Lateral geniculate cell responses to electrical stimulation of the retina.

Electrical stimulation of the retina evokes at the optic tract level rhythmic bursts of activity whose temporal structure is predictable from the polarity of the stimulation and the receptive field type. The reaction of lateral geniculate units to this input was studied in fast and slow relay cells as well as in interneurons. The results revealed that fast relaty cells presented a response whose temporal structure remained essentially unmodified in comparison to that observed at the optic tract level: that both anodal and cathodal polarities produced rythmic pattern of excitation the latency of which depended upon receptive field type and polarity applied. In slow relay cells and interneurons responses with equal latencies could be evoked for both polarities. Following cortical depression with 3 M KCl the latency of first bursts was unaffected in relay cells, while about one third of interneurons showed a temporal pattern which was similar to that recorded at the optic tract level after the treatment. This suggests that both ON and OFF retinal networks converge upon one geniculate slow P cell and interneuron, whereas fast relay cells are mostly driven by one of the two systems. Furthermore this convergence may be achieved through visual cortex in some units.

Animals↗
PubMed1988

Effects of BAY K 8644 on the responses of rabbit ear artery to electrical stimulation.

BAY K 8644 at 6.25 nM to 1 microM enhanced, in a concentration-dependent manner, both phases of the vasoconstrictor response of the isolated perfused rabbit ear artery to electrical stimulation. At 1 microM, BAY K 8644 enhanced the constrictor response by more than 250%. To study possible involvement of neurotransmitter release in the enhancement of the vasoconstrictor response by BAY K 8644, rabbit ear arteries were preincubated with [3H]norepinephrine and stimulated either electrically (for 1 or 5 min) or by 60 mM K+. BAY K 8644 (1 microM) had no effect on tritium release caused by 1-min periods of electrical stimulation. However, tritium release caused by 5-min periods of electrical stimulation or by 60 mM K+ was enhanced in the presence of BAY K 8644. It was concluded that BAY K 8644 enhances vasoconstrictor effects of electrical stimulation of rabbit ear artery by primarily a direct agonist action on Ca2+ channels in vascular smooth muscle cells. Following sustained depolarization, however, the drug may also enhance the release of neurotransmitter from sympathetic nerve endings. Under certain conditions, this release may contribute to the overall action of BAY K 8644.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1998

Effect of electrical stimulation of the thalamic Vim nucleus on hand tremor during stereotactic thalamotomy.

OBJECTIVE: The aim of this study was to analyze the correlation between neuronal responses in the thalamic ventralis intermedius (Vim) nucleus to peripheral, natural stimulation and the modulation of tremor by electrical stimulation during stereotactic thalamotomy. DESIGN AND METHODS: The authors studied 36 patients with hand tremor using a microelectrode. The responses of tremor to electrical stimulation were analysed electromyographically. Sixty stimulation sites were divided into three groups. RESULTS: Group A (20 sites) where responses to stretching of the contralateral forearm muscles were recorded. Group B (26 sites) where responses to stretching of the other muscles of the upper extremity were recorded. Electrical stimulation at sites in groups A and B temporarily suppressed the contralateral tremor, but the minimum current intensity to suppress tremor at sites in group A was less than that in group B. Electrical stimulation in group C (14 sites), where kinesthetic responses of contralateral lower extremity were recorded, resulted in increased amplitude of hand tremor. Selective coagulation including the area of tremor suppression resulted in abolition of the tremor in all patients. CONCLUSIONS: These results suggest that the most effective site for thalamotomy may also be suitable for chronic stimulation in the Vim nucleus.

Electric Stimulation↗
PubMed1983

Muscular strength development by electrical stimulation in healthy individuals.

The effects of electrical stimulation and its comparison with various resistance training modes were investigated in 34 subjects who trained their dominant leg isometrically three times a week for five weeks. Group E (n = 8) used maximum voluntary isometric contractions only, Group S (n = 8) received only electrical stimulation, and Group ES (n = 9) trained using a concurrent combination of isometric exercise and electrical stimulation. In addition, Group C (n = 9), a control group, did no experimental training. The expected gain in torque was shown in the isometric strength scores of the three experimental groups; however, there was little change in the isometric strength of the control group and in the isokinetic (100, 200, and 300 degrees/sec) results of any of the four groups. After adjustments were made for pretest strength results, a one-way analysis of covariance indicated that the posttest isometric strength scores of the three experimental groups differed significantly from those of the control group. No other posttest differences were found among any of the other training modes.

Adolescent↗
PubMed1984

Experimental model of electric stimulation of pseudarthrosis healing.

The effect of electric stimulation with direct constant current in induced pseudarthrosis was investigated in the radius of adult dogs. Two surgical techniques for inducing nonunion in the lower third of the radius of adult dogs are also described. Results were evaluated by clinical, radiologic, and histologic examinations and by 99mTc scintillation. A total of 57 animals (41 electrically stimulated and 16 control animals) was used. Statistically significant data show activation of endochrondral ossification and bone union by electric stimulation.

Animals↗
PubMed1983

The role of the septum in the control of the milk ejection reflex in the rat: effects of lesions and electrical stimulation.

Experiments were undertaken to determine the role of the septum on the afferent control of the milk ejection reflex in lactating rats. Massive septal lesions were produced by passing radio-frequency current through lesioning electrodes. Intramammary pressure recordings during suckling showed no significant alterations either in the frequency of milk ejections or in their amplitude and time course. Electrophysiological recordings of identified oxytocin-secreting neurones in supraoptic nuclei of septal-lesioned rats engaged in suckling showed that the pattern of background electrical activity and of the high frequency discharges at milk ejection were normal. The weight of litters from rats lesioned on the third day post-partum increased in a way parallel to that of control litters up to the fifteenth post-natal day. Electrical stimulation was applied bilaterally to the lateral septum in trains of long duration (20-55 min) at varying frequencies. Frequencies of 5 and 10 Hz interrupted the reflex during the period of stimulation. At 1 Hz, milk ejections were not interrupted but the intervals between successive milk ejections were significantly increased in comparison to the intervals before stimulation. Electrical stimulation applied to the septum in short trains of 1 or 3 min at 5 and 10 Hz significantly delayed the appearance of the subsequent milk ejection. At 1 Hz, no effect was observed. Septal stimulation at 1 Hz for 20 min or more did not significantly alter the electrocorticogram during the period of stimulation. Stimulation at 5 Hz for the same period of time always desynchronized the e.e.g. for several minutes after the cessation of stimulation. It is concluded that the septum is not essential for the onset and the maintenance of reflex milk ejections during lactation. The results suggest, however, that in the normal non-anaesthetized animal, septal activation could modulate the frequency of milk ejections.

Action Potentials↗
PubMed1997

Functional electrical stimulation.

In the health-care professions, electrical stimulation is used for three purposes: to aid diagnosis; as a therapeutic tool; and to restore lost or damaged functions. Functional electrical stimulation (FES) and functional neurostimulation (FNS) are terms which are more or less interchangeable, and which encompass the third of these purposes. FES itself can also be conveniently divided into three classes, according to purpose: the restoration of sensor functions; the restoration of skeleto-motor functions; and the restoration of autonomic functions. Potentially, a fourth class would comprise devices restoring cognitive or psychological functions, but no such devices are clinically available as yet. The methods and devices which are currently available for providing FES are reviewed, as are the sorts of result and benefit that may be expected from them. The structure and emphasis of the review is on the clinical applications and the relevant anatomical and neurophysiological considerations and this approach is chosen for two main reasons. Firstly, the clinical, anatomical, and physiological considerations are independent of technological change and development, so they will not become quickly out of date. Secondly, the author is a clinician by profession, and an engineer only by inclination. The functional aims of FES methods will continue to develop as a result of experience gained following the introduction and use of successful devices, and these evolutionary improvements will come from within the FES programme; but the engineering embodiment of those devices may be revolutionized at any time by technological advances coming from elsewhere.

Electric Stimulation↗
PubMed2004

[A clinical study of pelvic floor electrical stimulation in treatment of overactive bladder].

OBJECTIVE: To observe the efficacy of electrical stimulation in treatment of overactive bladder (OAB). METHODS: Patients (n = 60) with overactive bladder were randomly divided into 2 groups. Electrical stimulation group (n = 35) used an instrument for electrical stimulation through a special vagina or rectum probe transfer current (8-70 mA), for 20 min, qd, for 20-30 times. Medical group (n = 25) received oral tolterodine 2 mg, bid, for 2-4 weeks. RESULTS: The total effective rate and cure rate were 74%, 37% in electrical stimulation group and 76%, 40% in medical group, respectively, showing no significant difference between two groups (P > 0.05). While patients' satisfactory rate was significantly higher in electrical stimulation group than in medical group (P < 0.05). Side effects were more commonly seen with tolterodine. CONCLUSIONS: Electrical nerve stimulation is effective and safe for overactive bladder. Further studies are needed to show the long term efficacy and cost-effectiveness.

Adult↗
PubMedDate not supplied

Transretinal electrical stimulation with a suprachoroidal multichannel electrode in rabbit eyes.

PURPOSE: Several approaches for placing an electrode device for visual prosthesis have been previously proposed. In this study, we investigated if transretinal stimulation from the suprachoroidal space can elicit an electrical evoked potential (EEP) in albino rabbits. METHODS: A flat electrode array (polyimide plate, platinum electrode) was developed and used for this study. After performing a scleral incision at 2-2.5 mm from the limbus and placing an anchoring suture, the array was inserted into the suprachoroidal space in the posterior portion of the eye by direct observation under a microscope. A platinum wire was implanted into the vitreous space as a reference electrode. For electrical stimulation, a biphasic pulse was used. When the electrode was stimulated, the EEP was recorded. RESULTS: When the electrical stimulation from the suprachoroidal space was applied, the EEP could be recorded with an epidural electrode, and the threshold was 66.0 +/- 32.1 micro A (420 micro C/cm(2)) [corrected]. placement of the array and the electrical stimulation. CONCLUSIONS: Transretinal electrical stimulation from the suprachoroidal space could elicit EEP, suggesting that this approach may be useful for a retinal prosthesis system.

Animals↗
PubMed1993

Hair cell mediated responses of the auditory nerve to sinusoidal electrical stimulation of the cochlea in the cat.

Electrical stimulation of the cochlea elicits discharges of auditory nerve fibres which are mediated by the electrical or mechanical stimulation of inner hair cells (electrophonic responses). In order to isolate hair-cell mediated responses from those elicited by electrical stimulation of the nerve, the compound action potential (CAP) evoked by an acoustic probe was forward-masked by sinusoidal monopolar, or localized bipolar electrical stimulation of the base of the cochlea. The degree of masking of a given probe estimated the synaptically mediated response to the masker of the population of auditory nerve fibres innervating the cochlear location tuned to the probe. There was a peak of masking for probes close to the frequency of the electrical stimulus, suggesting a spatial tuning of the hair cell mediated response along the cochlea. This is consistent with excitation of the inner hair cells by a propagating mechanical response which is generated within the electrical field at the base of the cochlea. Furthermore, tuning curves for masking of a given probe were sharply tuned to electrical stimulation close to the probe frequency. This masking was not dependent upon the presence of functional outer hair cells close to the electrodes, suggesting an alternate transduction of electrical to mechanical energy.

Action Potentials↗
PubMed1987

Circulatory response of digital arteries associated with electrical stimulation of calf muscle in healthy subjects.

The purpose of this study was to investigate the effects of electrical stimulation (2,500-Hz sine wave modulated at 50 bursts per second) of the posterior calf musculature on the blood circulation of an unexercised part of the body, the ipsilateral digital arteries. Intensities of electrical stimulation sufficient to produce 15% and 30% of isometric maximum voluntary contraction (MVC) of the plantar flexor muscles were used. Twenty-four healthy subjects participated in this study and were assigned either to an Experimental Group receiving electrical stimulation (n = 13) or to a Control Group not receiving electrical stimulation (n = 11). Analysis of data revealed significant differences in finger blood flow when the calf musculature was stimulated electrically. We found significant differences in blood flow of the finger when torques produced by electrical stimulation of the calf musculature were raised to 15% and 30% of MVC. The results of the study indicate that blood flow in the ipsilateral finger decreases significantly when the posterior calf musculature is exercised artificially with electrical stimulation bursts.

Adult↗
PubMed1987

Effect of electrical stimulation current frequencies on isometric knee extension torque.

The purpose of this study was to compare the isometric knee extension torques of male and female subjects during maximal voluntary contractions (MVCs), electrical stimulation only, and electrical stimulation superimposed onto MVCs at electrical stimulation current frequencies of 20, 50, and 100 Hz. An asymmetrical, bidirectional, nonionizing waveform of 1-msec pulse duration was delivered through the femoral nerve and the superficial quadriceps femoris muscles at maximally tolerated intensity for each subject. The male subjects (n = 20) demonstrated significantly greater absolute torques under all contraction conditions than did the female subjects (n = 20) (p less than .01); when the torques were expressed as a percentage of each subject's MVC torque, however, no significant differences were observed between the sexes. Overall, the superimposed contractions at 50 and 100 Hz and the MVCs had similar torque values, all being significantly greater than the torque values produced by electrical stimulation only at frequencies of 20, 50, and 100 Hz and by the superimposed contractions at 20 Hz. Superimposing electrical stimulation onto MVCs did not result in greater torques than those produced by the MVCs alone. The three most effective contraction conditions, in terms of subject comfort (minimal discomfort) and increased torque, were the superimposed contractions at 50 and 100 Hz and MVCs alone, all of which involved a voluntary component.

Adolescent↗
PubMed1996

Electrical stimulation to restore respiration.

Electrical stimulation has been used for over 25 years to restore breathing to patients with high quadriplegia causing respiratory paralysis and patients with central alveolar hypoventilation. Three groups have developed electrical pacing systems for long-term support of respiration in humans. These systems consist of electrodes implanted on the phrenic nerves, connected by leads to a stimulator implanted under the skin, and powered and controlled from a battery-powered transmitter outside the body. The systems differ principally in the electrode design and stimulation waveform. Approximately 1,000 people worldwide have received one of the three phrenic pacing devices, most with strongly positive results: reduced risk of tracheal problems and chronic infection, the ability to speak and smell more normally, reduced risk of accidental interruption of respiration, greater independence, and reduced costs and time for ventilatory care. For patients with partial lesions of the phrenic nerves, intercostal muscle stimulation may supplement respiration.

Electric Stimulation Therapy↗
PubMed1983

Relaxation of rat tail artery to electrical stimulation.

Rat tail artery strips relax in response to electrical stimulation (0.1-8Hz, 9V, 1.0msec) following contraction induced by norepinephrine (5.9 X 10(-7)M). The relaxation is not altered by treatment of the strips with atropine, propranolol, tetrodotoxin or indomethacin nor by chemical denervation with 6-hydroxydopamine. Incubation of strips in calcium-free solution reduced the contractile response to norepinephrine and blocked relaxation in response to 4Hz electrical stimulation. Histamine antagonists (H2 receptor subclass: cimetidine, metiamide) inhibited the relaxation to electrical stimulation in a dose-dependent manner. These results suggest that relaxation to electrical stimulation in rat tail artery is modulated by calcium and by the H2 subclass of histamine receptors.

Animals↗