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PubMed1993

Rapid filopodial sprouting induced by electrical stimulation in nerve terminals.

Direct electrical stimulation of terminals of neurite-like extensions of cultured chromaffin cells and neuronally differentiated PC12 cells induced rapid sprouting of filopodia in a Ca dependent manner. Repetitive stimulation could produce filopodia with greater ease. Their formation could not be significantly suppressed by treatment with cytoskeletal blocking agents. Filopodial sprouting was localized to the terminal region only. This response may occur at the growth cone in vivo playing a role in neuronal development.

Animals↗

PubMed1986

Electrical stimulation releases 3H-betaxolol from rat atrial slices: possible role of noradrenergic nerves.

Under in vitro conditions, 3H-betaxolol was accumulated in rat atrial slices, reaching a tissue-medium ratio of 12.3 +/- 1.8 ml/g. This process was temperature-dependent, but ouabain-resistant. 3H-Betaxolol accumulated in atrial slices was subsequently released by electrical stimulation. The electrically-evoked release of 3H-betaxolol was abolished in the absence of calcium, and reduced in the presence of bretylium 10 microM. After surgical sympathetic denervation by stellate ganglionectomy there was a marked reduction in the endogenous content of noradrenaline and in the retention of 3H-noradrenaline in atrial slices. The concomitant decrease in the amount of 3H-noradrenaline released by electrical stimulation following denervation was modest, although statistically significant. Following sympathetic denervation, the tissue retention of 3H-betaxolol was not significantly affected, but the release of 3H-betaxolol by electrical stimulation was considerably reduced. After pretreatment with reserpine the amount of radioactivity released by electrical stimulation from slices labelled with 3H-betaxolol or 3H-noradrenaline was markedly reduced. The tissue retention of 3H-noradrenaline was reduced to a larger extent than that of 3H-betaxolol following the administration of reserpine. The simultaneous release of noradrenaline and betaxolol by nerve stimulation observed under our experimental conditions may represent a mechanism through which betaxolol can reach selectively the postsynaptic beta 1-adrenoceptors and reinforce beta-adrenoceptor blockade in the heart.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

[Spectral characteristics of the bioelectrical activity of the cerebral cortex upon electric stimulation of subcortical structures].

A spectral-correlation analysis of electrical activity of the rabbit cerebral cortex was made with the use of Dnieper computer, after electrical stimulation (100-250 c/s) of the midbrain reticular formation, the thalamic nonspecific formations (midline nuclei) and different nuclei of the posterior part of the hypothalamic area (ventromedial and posterior hypothalamic nuclei and the lateral field). The background spectrograms were characterized by a high variability; their frequencies ranged from 0,5 to 12 c/s. Under the influence of the electrical stimulation of the indicated formations, a well-pronounced, dominating peak appeared in the spectrograms of the cortical EEG, in the band from 4 to 7 c/s, and the similarity of biopotentials in this rhythm increased. The experimental data show that enhancement of spatial synchronization of the cortical biopotentials under conditions of electrical stimulation of the indicated subcortical formations is based on increased rhythmic oscillations within the theta-band and on a greater coherence in this range.

Animals↗

PubMed1991

Wild running and switch-off behavior elicited by electrical stimulation of the inferior colliculus: effect of anticonvulsant drugs.

The behavioral and motivational effects of electrical stimulation of the inferior colliculus (IC) were investigated. Electrical stimulations of either the dorsal part or ventral part of the IC both elicited wild running (WR). Nevertheless, the ventral part was found more sensitive than the dorsal part, as lower intensities were needed to elicit WR. Moreover, WR differed depending on the part of the IC stimulated. It stopped as soon as the stimulation was switched off when the ventral IC was stimulated, whereas it further persisted in a poststimulus WR when the dorsal IC was stimulated. This poststimulus WR was abolished by anticonvulsant drugs such as diazepam, phenytoin or sodium valproate. In an operant escape conditioning paradigm (switch-off test), only stimulation of the ventral IC readily sustained switch-off learning. Dorsal IC stimulations did not, possibly because of the poststimulus enduring effects of the stimulation, as evidenced by poststimulus WR. Indeed, the anticonvulsant drugs which abolished this poststimulus WR also permitted switch-off of dorsal IC stimulations. It is concluded that electrical stimulations of the IC (dorsal or ventral) elicit aversive effects and that WR elicited either by ventral or dorsal stimulation may represent the overt expression of these aversive effects.

Animals↗

PubMed1996

Intravesical electrical stimulation induces a prolonged decrease in micturition threshold volume in the rat.

PURPOSE: Intravesical electrical stimulation (IVES) has been used clinically to treat patients with voiding disorders. The aim of the present experimental study was to obtain objective evidence of a modulation of the micturition reflex by intravesical electrical stimulation (IVES). MATERIALS AND METHODS: Forty-one female rats, anesthetized by alpha-chloralose were used for the experiments. Intravesical electrical stimulation was given by a catheter electrode in the bladder (5 minutes of continuous stimulation at 20 Hz, 7 to 11 mA). The effect was evaluated by the change in cystometric micturition threshold volume. RESULTS: The threshold volume of the micturition reflex decreased significantly to 82% of controls after IVES (p<0.001; n=31). The effect was reversible and lasted for about 1 hour. The decrease was prevented by a transient blockade of the bladder nerves during IVES. CONCLUSIONS: Intravesical electrical stimulation induced a prolonged modulation of the micturition reflex in anesthetized rats. The effect was due to activation of bladder mechanoreceptor afferents and remained long after the period of stimulation. It is proposed that the modulation was due to a prolonged enhancement of excitatory synaptic transmission in the central micturition reflex pathway. Such a modulation may underlie the curative effect of IVES in certain voiding disorders.

Animals↗

PubMed1971

Summating potential with electrical stimulation of crossed olivocochlear bundles.

Electrical stimulation of crossed olivocochlear bandles resulted in increase of the positive summating potential in response to high-frequency tone bursts when the summating potential was recorded in the basal turn of the cochlea in anesthetized and immobilized guinea pigs. Strychnine locally applied suppressed the changes of the summating potential.

Action Potentials↗

PubMed1982

Electrical stimulation of the human brain.

Electrical stimulation of the human brain is one of the most exciting chapters in the story of experimental neurobiology. Since the first reported case of brain stimulation in a patient, by Bartholow in 1874, much progress has been made in this field. Today's methods of stimulation are much more subtle, and sophisticated methods for the assessment of the patient's experiences are used, as is shown by the following papers. The object of this issue is to provide an overview of the recent work in this field and to outline the influences it has, or should have, on our functional concepts of the human brain.

Brain↗

PubMed1993

Electrical stimulation to heal dermal wounds.

BACKGROUND: Numerous human and animal efficacy studies have demonstrated that electrical stimulation of the correct charge, density and total energy causes dramatically improved healing of dermal wounds. The investigations of biological actions (in vitro, animal, and human) demonstrate several effects that go a long way to explaining why electrical stimulation works. OBJECTIVE: To discuss recent research and advances in electrical stimulation of wound healing. RESULTS: Based on the latest scientific understanding of the wound healing process, one would expect a beneficial outcome from a therapy what decreases edema, debrides necrotic tissue, attracts neutrophils and macrophages, stimulates receptor sites for growth factors, stimulates growth of fibroblasts and granulation tissue, increases blood flow, stimulates neurite growth, induces epidermal cell migration, prevents post-ischemic oxygen radical-mediated damage, inhibits bacteria, and reduces numbers of mast cells. CONCLUSION: Taken together, the efficacy studies and the "mechanism of action" studies provide compelling, scientific evidence that electrical stimulation is safe and effective for promoting the healing of dermal wounds.

Animals↗

PubMed1979

Mapping the representation of the visual field by electrical stimulation of human visual cortex.

Electrical stimulation of human visual cortex produces punctuate phosphenes in the visual field. This phenomenon, which is being explored as the basis for a visual prosthesis for the blind, also provides the first electrophysiological information about the retinocortical map in man. Stimulation of points clustered on the surface of the visual cortex produces phosphenes clustered in visual space. However, adjacent surface electrodes located on opposite sides of a sulcus can produce widely separated phosphenes, because the intervening cortex is buried and inaccessible to stimulation. Such electrodes can also produce multiple phosphenes by simultaneously stimulating both banks of the sulcus. Electrodes which are widely spaced on the brain can produce phosphenes close together in visual space providing they stimulate cortex corresponding to overlapping maps in areas 17 and 18. Analysis of the phosphene map indicates that successive stimulation of points further from the tip of the occipital pole produces phosphenes progressively more distant from the fixation point. Successive stimulation of points along the orthogonal dorsoventral dimension produces a progressive change in phosphene bearing. These results confirm the general view of cortical organization derived from field defect studies in man, and from anatomical and electrophysiological studies in monkeys, and provide a new tool for more detailed study of retinotopic projections in man.

Adult↗

PubMedDate not supplied

Electric stimulation in chronic headaches.

Therapeutic electric stimulation in cases of chronic headaches was carried out in 150 patients. Migraine was diagnosed in 40 cases, common vasomotor headache in 63, cervical migraine in 24, Horton's neuralgia in 5 and complex headaches in 18 cases. The results are reported here, which were best in the cervical migraine syndrome, while in the typical migraine they were the least successful.

Adult↗

PubMed1975

Effects of electrical stimulation on human ovarian contractility.

Electrical stimulation was applied to the follicular walls, capsules of corpora lutea, and pieces of atrophic ovaries obtained from 29 human ovaries. The quantitative analysis of contractile capacity in these ovarian strips was performed on the basis of stimulation-response relationships. Only with follicular walls and capsules of corpora lutea was the step linear dose-response relationship similar to that shown by the uterine rube obtained by alternating current stimulation. The basal portions of mature follicular walls showed much more distinct responses to AC-stimulation than the apical portions. This difference further indicates a possible role of contractions by basal follicular walls in the process of follicular rupture at the apex in the human ovulation. The contractile elements of these ovarian strips were electronmicroscopically investigated with the strips which had shown contractions and confirmed to be smooth muscle cells in the ovary.

Adult↗

PubMedDate not supplied

Effect of in vivo electrical stimulation on the carbohydrate metabolism of control and denervation atrophied muscle of dog, Canis domesticus.

The standardized programme of electrical stimulation was applied to the control and denervation atrophied muscle of dog, Canis domesticus and the pattern of changes in the carbohydrate metabolism was analysed in the control (C), denervated control (DC), control stimulated (CS) and denervated stimulated (DS) gastrocnemius muscles. The programme of electrical stimulation of the control muscle has elevated glycogenolysis, glycolysis and increased the level of operation of TCA cycle with decreased mobilization of carbohydrates into hexose monophosphate pathway, indicating the setting in of trained condition. Sciatectomy, on the other hand, lowered the level of operation of glycogenolysis and decreased the utilization of carbohydrates through hexose-mono and di-phosphate pathways and TCA cycle. The programme of electrical stimulation applied to the denervated muscle has restored the utilization of carbohydrates through hexose mono and diphosphate pathways and oxidative metabolism indicating the applicability of this programme of electrical stimulation in the treatment of muscular atrophy.

Animals↗

PubMed1973

Predatory attack, grooming, and consummatory behaviors evoked by electrical stimulation of cat cerebellar nuclei.

Electrical stimulation at single sites in the rostral fastigial nucleus elicits hypertension, grooming, feeding, and attack behaviors in the cat. The stimulus intensity and availability of suitable goal objects determines the behavior. Bilateral lesions of the area fail to produce motor deficits. The rostral fastigial nucleus may be a cerebellar area for behavioral and autonomic regulation.

Aggression↗

PubMedDate not supplied

[Electrical stimulation of the vagal nerve: from experimental to clinical aspects].

INTRODUCTION AND AIMS: This review focuses its attention on the studies that have been conducted to determine the influence of electrical stimulation of the vagal nerve on experimentally induced convulsive activity and its application in the clinical field. The literature published to date describes an anticonvulsive effect on the seizures triggered by pharmacological agents and by electrical stimulation such as electroshock, and in the amygdaline electrical kindling model a delay in the generalisation of the convulsive activity is observed. DEVELOPMENT: The first experimental observations showed that electrical stimulation of the vagal nerve can have effects on EEG activity, including synchronisation and desynchronisation of the electrical activity of the brain, as well as promoting an increase in the amount of REM sleep. These observations served as the basis for the renewed interest in the electrical stimulation of the vagal nerve in experimental models and testing its effectiveness in patients with medication-resistant epilepsy. Nevertheless, the mechanisms accounting for the anticonvulsive effect remain unknown. CONCLUSIONS: These observations open up the possibility of studying the role played by neurotransmitters and neuromodulators in the anticonvulsive process of the electrical stimulation of the vagal nerve in experimental models of epilepsy and offer evidence of its possible action in the human brain.

Electric Stimulation↗

PubMed1983

Frequency-dependent activation of glucose utilization in the superior cervical ganglion by electrical stimulation of cervical sympathetic trunk.

Electrical stimulation of the distal stump of the transected cervical sympathetic trunk produces a frequency-dependent activation of glucose utilization, measured by the deoxy[14C]glucose method, in the superior cervical ganglion of the urethane-anesthetized rat. The frequency dependence falls between 0-15 Hz; at 20 Hz the activation of glucose utilization is no greater than at 15 Hz. Deafferentation of the superior cervical ganglion is transection of the cervical sympathetic trunk does not diminish the rate of glucose utilization in the ganglion in the urethane-anesthetized rat. These results indicate that the rate of energy metabolism in an innervated neural structure is, at least in part, regulated by the impulse frequency of the electrical input to the structure, and this regulation may be an essential component of the mechanism of the coupling of metabolic activity to functional activity in the nervous system.

Animals↗

PubMed1991

[Visual illusions during the electrical stimulation of the labyrinth].

Transcutaneous electrical stimulation of the labyrinth induced apparent motion of a stationary light source in darkness in normal subjects. This effect is similar to the oculogyric illusion induced by rotatory vestibular stimulation. Monaural anodal stimulation of the right labyrinth evoked apparent movement of the target to the left, whereas cathodal stimulation induced opposite illusion. The threshold current was 0.35-0.6 mA. Binaural bipolar stimuli induced illusory target motion directed to the side of the cathode, the threshold decreased 1.5-2.5 times. Binaural monopolar stimulation induced vertical apparent displacement of a target, the threshold being 1.4-3.0 mA. The amplitude and velocity of illusory target motion increased with current. The subject eyes began to move with much higher currents than those necessary for illusory sensation. It is therefore suggested that the visual illusion is related not to vestibulo-visual interaction but to vestibular effects on the spatial perception system.

Darkness↗

PubMed1995

Reflex reversal of apnoeic episodes by electrical stimulation of upper airway in cats.

Respiratory effects of electrical stimulation of the upper airways (UAW) before and during apnoeic episodes induced by nitrogen inhalation were studied in 9 anaesthetized cats. In eupnoeic animals these electrically-evoked reflexes comprise rapid and powerful inspiratory efforts characterized by strong maximal airway occlusion pressures (Pmax = 635 +/- 39 mm H2O) and rapid peak inspiratory flow rates (PIF = 536 +/- 36 ml.sec-1) similar to the sniff-like aspiration reflex elicited mechanically. Electrical stimulation of the UAW mucosa can elicit reflex inspirations and sniff-like aspiration reflexes even during reversible hypoxic apnoea but their intensity and reproducibility are transiently reduced. When repeated adequately, the electrically-induced reflexes can increase the reactivity of respiratory centre and interrupt or terminate apnoeic episodes as do other types of UAW stimulation. Reflex mechanisms and respiratory centre activations seem to be involved in these effects. The results suggest that electrical stimulation of UAW could be useful for testing the respiratory centre reactivity as well as for reflex reversal of apnoeic episodes and restoration of normal breathing in animal experiments and clinico-physiological studies. Such investigation of the role of UAW reflexes in the pathogenesis and therapy of apnoeic syndromes might also be possible by using a cardiostimulator adapted as respiratory pacemaker.

Animals↗

PubMed1978

[Hemodynamics in atrioventricular block in acute myocardial infarct and its changes under the influence of electric stimulation of the heart].

Hemodynamics was studied in the initial condition and against the background of electric stimulation of the heart in 18 patients with acute myocardial infarction complicated by complete atrioventricular block. It is shown that block promotes the development of circulatory insufficiency in patients with myocardial infarction. The marked character of hemodynamic disorders and the changes induced in it by electric stimulation are determined in many respects by the functional condition of the left ventricle. In most patients with acute myocardial infarction complicated by complete atrioventricular block, with the exception of those with a clinical picture of cardiogenic shock, the main values of hemodynamics demonstrated against the background of electric stimulation hardly differ from the corresponding values in patients with myocardial infarction and no disturbances of atrioventricular conduction. During electric stimulation of the heart in the contingent of patients examined, the external work of the heart and the "tension/time" index considerably increase which suggests a marked increase in the myocardium requirements in oxygen. The probability of unbalanced increase in the requirements of the myocardium in oxygen against the background of electric stimulation dictates the necessity for raising its parameters to optimum levels.

Acute Disease↗