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At least 145 records · Page 8Linked to original sources
PubMed2000

Muscular reflexes elicited by electrical stimulation of the anterior cruciate ligament in humans.

Anterior cruciate ligament (ACL)-deficient knees have impaired proprioception, and, although mechanoreceptors have been found in the ACL, the existence of a reflex elicited from these receptors has not been directly demonstrated in humans. In eight patients that underwent knee arthroscopy and had no sign of ACL disease, thin wire electrodes were inserted into the proximal and mid parts of the ACL. Postoperatively, the sensory nerve fibers inside the ACL were stimulated electrically while motor activity in the knee muscles was recorded using electromyography. In seven of the eight patients, a muscular contraction of the semitendinosus muscle could be elicited with stimulus trains consisting of at least two stimuli. The latency was 95 +/- 35 ms. Stimulation during isometric contraction of either extensor or flexor muscles elicited a short, complete inhibition of the muscle activity in the contracting muscles. The latency of the inhibitory responses was 65 +/- 20 ms in the semitendinosus muscle and 70 +/- 15 ms in the rectus femoris muscle.

Adult↗
PubMed1993

Evans blue extravasation in rat dental pulp and oral tissues induced by electrical stimulation of the inferior alveolar nerve.

Whether increased extravasation of plasma protein may occur in the rat incisor pulp as a result of antidromic stimulation of afferent nerves was investigated, and this preinflammatory reaction compared with that in adjacent soft tissues. In anaesthetized rats, the inferior alveolar nerve was exposed and stimulated electrically (10-15 V, 2 ms, 10 Hz for 30 s or 5 min). Blood flow changes in the lower lip and incisor pulp were recorded by laser Doppler flowmetry. Increased vascular permeability in the lip, gingiva and pulp was indirectly determined by means of the Evans blue dye method and spectrophotometric analysis. Stimulation of the inferior alveolar nerve for 30 s, in the presence of the alpha-adrenergic blocker phenoxybenzamine (3 mg/kg), increased blood flow in the lip by 172 +/- 16% and in the pulp by 38 +/- 5% as compared to basal blood flow. Intravenous (i.v.) administration of atropine (1 mg/kg), chlorisondamine (3 mg/kg), timolol (150 micrograms/kg), cimetidine plus mepyramine (3 mg/kg of each), methysergide (1 mg/kg) and diclofenac sodium (3 mg/kg) was without effect on this response. Acute pretreatment with capsaicin (1-3 mg/kg, i.v.), however, abolished the vasodilation in the pulp and reduced that in the lip by 58% (p < 0.05). In untreated animals, stimulation of the inferior alveolar nerve for 5 min increased the Evans blue content in the ipsilateral lip by 164% (p < 0.001), gingiva by 55% (p < 0.01) and pulp by 67% (p < 0.01). Pretreatment (i.v.) with a combination of cimetidine and mepyramine counteracted the dye extravasation only in the gingiva.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Fast to slow transformation of denervated and electrically stimulated rat muscle.

1. Denervated fast extensor digitorum longus (EDL) muscles of adult rats were stimulated electrically for up to 4 months with a slow pattern resembling the activity in soleus (Sol) motor units and examined with antibodies against myosin heavy chains (MHCs). 2. The normal EDL contained, on average, 45% type IIB, 29% type IIX, 23% type IIA and 3% type I fibres. All type IIB and almost all type IIX fibres disappeared during the first 3 weeks of stimulation. They were replaced by type IIA and type I fibres, whose percentages increased to about 75 and 15, respectively. Type IIA fibres remained at 75% for nearly 2 months and were then gradually replaced by type I fibres during the next 2 months. The transformation occurred sequentially in the order IIB/IIX-->IIA-->I, the first step (IIB/IIX-->IIA) occurring after a short delay (2 weeks) and the last step (IIA-->I in originally IIB or IIX fibres) after a long delay (> 2 months). During the transformation coexpression of MHCs occurred. 3. It appears that the transformation to type I fibres occurred in pre-existing type II fibres since no signs of fibre damage or regeneration were observed. 4. Normal EDL was also stimulated through an intact nerve with the same pattern for up to 37 days. The effects on fibre type distributions were identical to those observed in the denervated EDL. The result indicated that the Sol-like pattern of evoked muscle activity, rather than nerve-derived trophic influences or denervation per se, was primarily responsible for the fast to slow transformation.

Animals↗
PubMed1986

Investigation of cochlear mechanisms using combined acoustical and electrical stimulations.

Electrically-evoked VIIIth nerve CAP responses evoked by electrical stimulation and derived by masking with sounds are recorded in the guinea pig, using different masking paradigms (pure tones and high-pass filtered white noise). CAP frequency threshold curves correlate with threshold curves determined by other means, in normal as well as in pathological guinea pigs. Amplitudes of the responses as a function of pure tones frequency and intensity are also measured. Such measurements provide an estimate of the number of fibers activated by the pure tones. These responses can be further analysed using masking with high-pass filtered white noise.

Acoustic Stimulation↗
PubMed1987

Schistosoma mansoni: effects of bromolysergic acid diethylamide, verapamil, and Ca2+-free solution on the motor activity of the isolated male worm induced by electrical stimulation and oxamniquine.

Electrical stimulation and oxamniquine effect the motor activity of isolated Schistosoma mansoni. Electrical stimulation produced contractions that increased with stimulus intensity. Oxamniquine (10(-4) M) produced an increase in basal tonus and in the frequency and amplitude of the worm's spontaneous contractions. Incubation in the absence of calcium produced a decrease in the basal tonus, abolished the spontaneous contractions of S. mansoni, and abolished the mechanical response induced by electrical stimulation and oxamniquine. The effects of electrical stimulation and oxamniquine were, respectively, significantly reduced and abolished by 10(-6) M verapamil (a calcium channel blocking agent). Bromolysergic acid diethylamide (3 X 10(-5) M), a serotonin blocking agent, reduced the motor response induced by high intensity electrical stimulation and blocked the response induced by oxamniquine. The effects of low intensity electrical stimulation were not modified in the presence of bromolysergic acid. We think that external Ca2+ is important for basal tonus, for spontaneous motor activity, and for motor responses of S. mansoni induced by electrical stimulation and oxamniquine. Serotonin may be important for mechanical responses induced by high intensity electrical stimulation and for responses induced by oxamniquine.

Animals↗
PubMed1982

Desynchronized sleep-like pattern of sympathetic activity elicited by electrical stimulation of sites in the brainstem.

In unanaesthetized mid-collicular decrebrate cats, paralyzed and artificially respired, recordings were made of sympathetic activity in nerves to heart (CN), to kidney (RN) and in identified vasoconstrictor nerves to skeletal muscle (SFM), whilst stimulating electrically with monopolar electrodes at various sites throughout the pons and medulla. Comparing RN and SFM, 1 of 3 patterns of response was observed at any one site: an increase in RN and SFM activity, a reduction or abolition of activity in both or a reduction or abolition of RN activity with a simultaneous facilitation of SFM activity. The latter differential pattern of sympathetic activity is characteristic of desynchronized sleep-like periods and could only be elicited from a discrete region in the mid-line of the caudal brainstem. Stimulation in this same region produced a reduction or abolition of CN as well as RN. It was suggested that neurones within the caudal part of nucleus raphe obscurus can generate a pattern of sympathetic activity similar to that occurring naturally in desynchronized sleep.

Animals↗
PubMed1998

Histamine H1-receptor-mediated increase in the Ca2+ transient without a change in the Ca2+ current in electrically stimulated guinea-pig atrial myocytes.

The effects of histamine on the intracellular Ca2+ concentration ([Ca2+]i), action potential and membrane currents were assessed in single atrial myocytes prepared from guinea-pigs. Histamine caused a concentration-dependent increase in the [Ca2+]i transient in indol/AM loaded myocytes when stimulated electrically at 0.5 Hz. However, the maximum increase in [Ca2+]i transient produced by histamine was less than 50% of that elicited by isoprenaline. The histamine-induced increase in [Ca2+]i transient was significantly inhibited by chlorpheniramine, but not by cimetidine. Pretreatment with nifedipine nearly completely suppressed the histamine-induced increase in [Ca2+]i transient. Cyclopiazonic acid did not affect the histamine response. In the whole-cell current-clamp mode of the patch-clamp method, both histamine and isoprenaline prolonged action potential duration (APD) in atrial myocytes. In the presence of Co2+ or nifedipine, the isoprenaline-induced APD prolongation was abolished and an APD shortening effect was manifested, while histamine still increased APD. The APD prolongation elicited by histamine was reversed by chlorpheniramine. In the voltage-clamp mode, the histamine-sensitive membrane current was inwardly rectifying and reversed close to the calculated value of the K+ equilibrium potential. Histamine had no apparent effect on L-type Ca2+ current, in contrast to the pronounced effect of isoprenaline. These results indicate that in guinea-pig atrial myocytes stimulation of H1-receptors with histamine does not directly activate Ca2+ channels but causes an elevation of [Ca2+]i transient by increasing Ca2+ influx through the channels during the prolonged repolarization of action potentials resulting from inhibition of the outward K+ current.

Action Potentials↗
PubMed1984

Bladder inhibition by penile electrical stimulation.

Transcutaneous electrical stimulation was applied to the penis in 22 patients complaining of frequency, urgency and/or urge incontinence. Detrusor activity was suppressed with this stimulation, causing decreased bladder spasticity and/or increased cystometric capacity in 10 of 22 patients. Clinical success was noted in four patients with a portable stimulator.

Adolescent↗
PubMed2006

Effects of transcranial direct current stimulation coupled with repetitive electrical stimulation on cortical spreading depression.

We have recently shown that two techniques of brain stimulation - repetitive electrical stimulation (ES) (that mimics transcranial magnetic stimulation) and transcranial direct current stimulation (tDCS) - modify the velocity of cortical spreading depression (CSD) significantly. Herein we aimed to study the effects of these two techniques combined on CSD. Thirty-two Wistar rats were divided into four groups according to the treatment: sham tDCS/sham ES, sham tDCS/1 Hz ES, anodal tDCS/1 Hz ES, cathodal tDCS/1 Hz ES. Our findings show that 1 Hz ES reduced CSD velocity, and this effect was modified by either anodal or cathodal tDCS. Anodal tDCS induced larger effects than cathodal tDCS. Hereby CSD velocity was actually increased significantly after anodal tDCS/1 Hz ES. Our results show that combining two techniques of brain stimulation can modify significantly the effects of ES alone on cortical excitability as measured by the neurophysiological parameter of cortical spreading depression and therefore provide important insights into the effects of this new approach of brain stimulation on cortical activity.

Animals↗
PubMed2006

An energy algorithm improves symptoms in some patients with gastroparesis and treated with gastric electrical stimulation.

Gastric electrical stimulation (GES) is effective to improve symptoms of nausea and vomiting in most patients, but very little is known about the effect of varying stimulation parameters. We analysed stimulation parameters in a pilot study of 22 patients (12 idiopathic, four diabetic and four postsurgical) with drug-refractory gastroparesis who did not respond optimally to initial settings. Patients underwent high-frequency/low energy GES using identical initial stimulation parameters: 5 mA of current, 330 micros pulse width, 14 Hz for 0.1 s on and 5.0 s off. Due to lack on optimal response, 22 patients underwent alteration of an algorithm using stimulation parameters. At follow-up (mean of 4.3 years) a dose-response relationship for charge, power and energy were compared with baseline for the whole group and for each diagnostic subgroup by anova data are reported as mean +/- SE. Based on the mean of individual dose-response curves, differences in data are charge, current per pulse and energy per pulse were noted for the whole group at follow up vs baseline. The subgroup of patients with postsurgical gastroparesis required the most energy using the algorithm. In conclusion, an algorithmic approach to identify optimal stimulation parameters in GES for individual patients is associated with symptom improvement. Also, certain subgroups appear to have different energy parameters. Based on this preliminary data, the use of an algorithm for some patients with GES is feasible and may have potential for clinical application. A randomized-controlled trial of different stimulation parameters for GES seems warranted.

Adult↗
PubMed1987

Changes in monoamine content of the rabbit carotid body following prolonged electrical stimulation of the carotid sinus nerve.

In the anaesthetized, paralysed and artificially ventilated rabbit the carotid sinus nerve (CSN) has been stimulated electrically for 6 h. At the end of the stimulation period, the carotid body (CB) has been removed, frozen and processed for measurement of the monoamines (MA) and of their catabolites with high-pressure liquid chromatography and electrochemical detection (HPLC-ECD). Results show a significant increase of dopamine (DA) and adrenaline (A) content and of all the metabolites. Besides an important augmentation of DA metabolism suggests that CSN efferent activity exerts some regulation on the MA content and turnover of the CB.

Animals↗
PubMed1983

'Vomiting center' reanalyzed: an electrical stimulation study.

Electrical stimulation of the brainstem of 15 decerebrate cats produced stimulus-bound vomiting in only 4 animals. Vomiting was reproducible in only one cat. Effective stimulating sites were located in the solitary tract and reticular formation. Restricted localization of a 'vomiting center', stimulation of which evoked readily reproducible results, could not be obtained.

Animals↗
PubMed1991

Canine-specific adaptation of energy metabolism of latissimus dorsi muscle in response to chronic electrical stimulation.

Continuous electrical stimulation ot canine latissimus dorsi (LD) muscle in situ during 24 weeks induced an increase of immunohistochemically assayed type I fibers from about 30 to 80%. Concomitantly, the activity of fructose-6-phosphate kinase, a key enzyme of the glycolytic pathway, declined markedly, but the capacity for fatty acid oxidation remained unaltered. With respect to myofibrillar and metabolic properties the dog LD muscle initially resembled soleus muscle, and after 24 weeks of stimulation had acquired the properties of gastrocnemius muscle. It is concluded that in the dog, unlike the rat, the LD muscle has an inherently fixed capacity for oxidative energy production. Further expansion of its resistance to fatigue, as induced by chronic stimulation, most likely results mainly from a more efficient coupling between tension development and energy production.

Adaptation, Physiological↗
PubMed1988

Enhancement of gait restoration in spinal injured patients by functional electrical stimulation.

Functional electrical stimulation (FES) was applied in 50 spinal cord injury patients in an effort to restore standing and walking. All patients in the program with lesions from T4-T12 were able to stand by means of FES. Walking, utilizing a four-channel stimulator, was accomplished by 25 patients with lesions in the range from T4-T12. These 25 patients represent approximately 5% of all spinal cord injured patients treated in the authors' rehabilitation facility during this time period. After using the stimulation in a home environment for more than three months, the number of patients who continued to use the stimulation for walking declined, and 16 patients remained ambulatory. The discontinuance of FES was mainly because of the time required to put on and operate the FES system and difficulties adapting to a new home environment and living situation.

Adolescent↗
PubMed2006

The role of the right superior temporal gyrus in visual search-insights from intraoperative electrical stimulation.

Intraoperative electrical stimulation in awake patients is a seminal technique during brain surgery allowing one to infer the function of brain areas by temporary inactivation. Using this technique, we found that inactivation of the middle portion of the superior temporal gyrus (STG) leads to disturbed serial exploratory visual search. The data supplement recent findings by Ellison et al. [Ellison, A., Schindler, I., Pattison, L. L., & Milner, A. D. (2004). An exploration of the role of the superior temporal gyrus in visual search and spatial perception using TMS. Brain, 127, 2307-2315] using repetitive transcranial magnetic stimulation over the STG in healthy subjects. Our data demonstrate that the STG is integral to human exploration behaviour and challenge the traditional view that only the right posterior parietal cortex is involved in the mediation of visual search processes.

Aged↗
PubMed1994

Technical approach for reanimation of the chronically denervated larynx by means of functional electrical stimulation.

Functional electrical stimulation (FES) of the posterior cricoarytenoid (PCA) muscle to produce vocal fold abduction offers an alternative approach to current surgical therapies for bilateral vocal fold paralysis. The purpose of this study was to characterize the application of FES to chronically denervated PCA muscles. Specific goals were to develop a stimulus delivery system for the PCA muscle, determine a practical means of implantation, and identify stimulus parameters effective in activating chronically denervated muscle. Seventeen dogs were implanted with planar electrode arrays 3 months after unilateral recurrent laryngeal nerve resection. A nail-bed electrode array allowed discrete activation of the PCA muscle and gave the greatest abductions, with minimal charge dissipation. Muscle mapping revealed hot-spot regions on the PCA muscle surface, in which stimulation produced maximum abduction. A conservative stimulus paradigm effective in activating chronically denervated muscle was a 1-second pulse train of 2-millisecond-duration pulses, delivered at a tetanizing frequency of 30 Hz and an amplitude of 4 to 14 mA.

Animals↗
PubMed1983

The neurophysiological basis of bladder inhibition in response to intravaginal electrical stimulation.

Intravaginal electrical stimulation (IVS) induces a profound bladder inhibition and is successful in the treatment of incontinence due to detrusor instability. In this experimental study in cats, direct recordings of the efferent activity in thin hypogastric and pelvic nerve filaments to the bladder were used to analyze the neuronal mechanisms underlying this bladder inhibition. A longlasting reflex discharge, with a latency of 35 to 50 msec., was evoked in the hypogastric nerve by IVS. The reflex discharge was unaffected by imposed changes in intravesical pressure or by micturition contractions, but the response was very frequency-sensitive with an optimal transmission at about 5 Hz of stimulation. A "spontaneous" efferent activity could be recorded in the pelvic nerve filaments when the bladder pressure was elevated above 5 to 7 cm. H2O. The pelvic activity occurred in 10 to 20-second bursts, each followed by an abortive detrusor contraction. IVS of 5 to 10 Hz completely abolished this efferent pelvic activity by central inhibition. The findings are discussed in relation to the normal neuronal control of the bladder and to the clinical application of IVS.

Action Potentials↗