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Various electrical devices are implanted for cardiac-, diaphragma-, pain- and musclestimulation. The stimulator/pacemaker can be implanted in locations, different from that of ordinary cardiac pacemakers. All electric stimulation equipment containing batteries must be removed before cremation on account of the risk of explosion.
A portable lightweight stimulator for small animals is described. It delivers pulse trains of high intensity and is convenient for denervated muscle studies. It does not cause discomfort and does not restrict activity.
1. This study examines the effect on auditory desensitization of electrically stimulating the crossed olivocochlear bundle (COCB) at the floor of the fourth ventricle. Auditory desensitization was induced by a loud high-frequency pure tone exposure and measured as temporary threshold shifts (TTS) in the sensitivity of the compound action potential recorded from the cochlea. COCB stimulation simultaneous with the loud sound exposure reduced the TTS. This reduction was contingent on the COCB stimulus being presented as a continuous burst for the entire duration (1 min) of the exposure. 2. The reduction in TTS could be abolished by prior administration of strychnine. The action of strychnine on these TTS effects of continuous COCB stimulation paralleled its action on the classical COCB effects elicited by pulsed short COCB trains. If the action of strychnine on the classical COCB effects was allowed to reverse, then continuous COCB stimulation reduced TTS as effectively as before. 3. The most effective COCB stimulus was found to be one that was presented at a high rate of stimulation simultaneous with the exposure. The COCB effect on TTS was also found to be a tonic one; smaller but significant reductions in TTS could still be obtained with the exposure presented 5 min after COCB stimulation though not when the delay was 10 min. The tonic reductions in TTS appeared to occur without any persisting changes at the cochlea. Normal cochlear responses remeasured in the delay between the stimulus and exposure were not altered. 4. It was hypothesized that the persisting effect responsible for TTS reductions did not occur at the cochlea but at some central site facilitated by antidromic action potentials along the COCB fibers. Subsequent exposure to loud sounds would activate the central site primed by the prior COCB stimulus. This hypothesis was tested by stimulating the COCB alone as before, but then lesioning the fibers before presenting the exposure. Persistent cochlear effects of the COCB stimulus should have still resulted in a reduction in TTS. However, if the persistent effect was at a more central location, lesioning the fibers would allow afferent input to act at the facilitated central location but would not allow subsequent expression of COCB effects at the cochlea. In this case, no reductions in TTS could be expected--precisely the results that were obtained in these experiments. Thus the COCB system appeared to have a "memory" component facilitated by prior stimulation and activated by a subsequent exposure.
The release of both radioactive and endogenous purines was investigated in rat brain cortical, hippocampal and striatal slices at rest and following stimulation with electrical fields. Purines were labelled by incubating the slices with 3H-adenine. The purine efflux at rest and that evoked by electrical stimulation (10 Hz. 5 min) was analyzed by HPLC with ultraviolet absorbance detection. Both radioactive and endogenous purines in the effluent consisted mainly of hypoxanthine, xanthine, inosine and adenosine. No qualitative differences in the composition of the released purines were found in the three areas investigated. Electrical stimulation evoked a net increase in both radioactive and endogenous purine release. However the increase in 3H-adenosine following electrical stimulation was twice as large as that of endogenous adenosine. The electrically evoked release of both radioactive and endogenous purines was greatest in hippocampal slices and progressively smaller in cortical and striatal slices. In the three areas the addition of 0.5 microM tetrodotoxin to the superfusing Krebs solution brought about a similar (83-100%) reduction in evoked 3H-purine and endogenous purine release. Superfusion of the slices with calcium-free Krebs solution containing 0.5 mM EGTA reduced evoked release of 3H-purines by 58-60% and that of endogenous purine components by 54-89%. The results demonstrate similar characteristics for both radioactive and endogenous purine release but indicate that the most recently synthetized adenosine is the most readily available for release. The features of the electrically evoked purine release support a neuronal origin of adenosine and derivatives and are consistent with the hypothesis of discrete regional differences in adenosine neuromodulation.
The relationship between intracranial self-stimulation (ICSS) and stimulation-produced analgesia (SPA) was investigated in that rat employing an operant bar-press response and a modification of the hot-plate test. ICSS and SPA were elicited through bipolar electrodes chronically implanted in two catecholamine nuclei; the nucleus locus coeruleus (LC) and the substantia nigra (SN). These sites have previously been shown to yield both phenomena. SPA was shown to be of a magnitude similar to that of morphine. In addition, SPA deriving from both LC and SN was significantly reversed by the specific opiate antagonist, naloxone. The intensity of the stimulating current sufficient to induce SPA was found to be higher than that required for ICSS. The pharmacological susceptibilities of the two phenomena were tested by administering a number of drugs: haloperidol, propranolol, pimozide and AMPT attenuated ICSS in both LC and SN, while leaving SPA unaffected. In contrast, methysergide and PCPA blocked SPA and simultaneously facilitated ICSS. The present results indicate a dissociation of ICSS and SPA from LC and SN at both physiological and neurochemical levels; ICSS rates appeared to be a function of catecholaminergic tone, while SPA depended upon the integrity of serotonin transmission.
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Extracellular recording techniques were used to investigate the effects of focal brain stimulation and external electrical stimulation on spontaneous activity and on noxious evoked responses in the habenular nucleus of anesthetized Sprague-Dawley rats. Two hundred and forty-one habenular neurons were tested to noxious and non-noxious stimuli. The habenular neurons exhibited three cell types according to their patterns of response to the noxious stimulus: 123 neurons (51%) responded to noxious stimulus by excitation and were classified as "nociceptive-on" cells; 56 neurons (23%) responded to the same noxious stimulus by decreasing their firing rate and were classified as "nociceptive-off" cells; and 62 neurons (26%) failed to respond to noxious stimulation and were classified as "non-nociceptive" cells. None of these 241 cells responded to non-noxious stimulus. One hundred and fifty-five, 160, 142 and 241 habenular neurons were tested following focal lateral hypothalamus stimulation, dorsal raphe stimulation, cerebellar stimulation and transcranial electrical stimulation alone and concomitant with noxious stimulation, respectively. The observations demonstrate that focal lateral hypothalamic, dorsal raphe and external (transcranial) electrical stimulation suppresses habenular noxious evoked responses while cerebellar electrical stimulation elicits no effect on the nociceptive-off cells and augmenting effects on the nociceptive-on cells. In addition, it was observed that low current (below threshold) external transcranial electrical stimulation was as effective in suppression of habenular noxious evoked responses as was focal brain electrical stimulation in the lateral hypothalamus and dorsal raphe.
Conventional programmed electrical stimulation (PES) of the ventricle is useful for establishing inducibility or noninducibility of clinical ventricular arrhythmias (VA) but is complex and time consuming. The present study was designed to compare a standard PES protocol with an alternative method using ultrarapid train stimulation in patients with VA and coronary artery disease (CAD). A prospective, randomized, crossover design was used. During each session in the electrophysiology laboratory, patients were studied using both the trains and PES protocols in randomized order. In 82 matched pairs of comparisons in 50 patients, results were concordant in 85% (p < 0.0001). There were no differences related to type of clinical arrhythmia or to the presence of antiarrhythmic drugs. There were no significant differences in the induction of nonclinical arrhythmias with the two methods (p < 0.0001 for concordance). There were no significant differences related to the cycle length of the trains (10, 20, or 30 ms, equivalent to 100, 50, or 33 Hz). The number of drive-extrastimuli sequences and the time required to complete the trains protocol was significantly shorter (p < 0.0001) using trains versus PES. Ultrarapid train stimulation provides results in CAD patients that are comparable with those of conventional PES protocols. There is a significant savings in time, adding practical value to intrinsic electrophysiologic interest. Trains may be useful when multiple inductions are desirable, for example, in the setting of antitachycardia pacing parameters in an implantable defibrillator (ICD), during ICD implantation, or in other circumstances where the main question is inducibility of ventricular arrhythmias.
The purpose of this study was to answer the following questions: (1) Is it more effective to treat spastic cerebral palsy with the Hufschmidt electrical stimulation therapy combined with the Bobath neuro-development treatment or only with the Bobath therapy? (2) Can a general increase in activity be obtained by the electrotherapeutic muscle stimulation? A test group (combined Hufschmidt/Bobath therapy) and a control group (Bobath), both consisting of 10 subjects, were observed for four months. The duration of observation was divided into two four months treatment periods with a rest interval of two months in between. At the start of therapeutic measures, motor activity and psychic condition were tested with corresponding motormetric and psychodiagnostic techniques; three check-up examinations were carried out at the end of the first, and at the beginning and end of the second period of treatment. The motor-metric control examination showed that at the end of the first period the test group had achieved by far the better results, but at the end of the second therapeutic period, both groups were equally successful. The combined electrophysiotherapy hence reached in a relatively shorter time - as it were by leaps and bounds - the optimal obtainable state of functional improvements which, with the Bobath therapy alone, can be effected more slowly but with more continuity. The psychodiagnostic controls clearly indicate that the electrical stimulation produced an unspecified increase in activity, especially after the first phase of treatment, whereas in the second phase this could only be proven in a graded form. The report closes with an examination of the results and their consequences for the implementation of the treatment for cerebral palsied children.
In vivo electrical stimulations were applied to the gastrocnemius muscles of intact frogs for prolonged periods which lead to improved muscular efficiency and delayed onset of fatigue. The muscular strength improvement was correlated to increased tissue contractile proteins and decreased collagen content. Elevated levels of muscular fuels, mitochondrial content, oxidative metabolism in the stimulated muscles were suggested to be responsible for the delayed onset of fatigue. In view in these characteristics regarding the improvement at physical and metabolic levels, the muscles exposed to chronic electrical stimulations were termed as trained muscles. The applicability of electrical stimulations to induce the training effects into the muscles in atrophic and dystrophic conditions to avert the muscle wastings was suggested.
OBJECTIVE: Electrical stimulation can be applied in a variety of ways to the hemiparetic upper extremity following stroke. The aim of this review is to explore the relationship between characteristics of stimulation and the effect of electrical stimulation on the recovery of upper limb motor control following stroke. METHODS: A systematic literature search was performed to identify clinical trials evaluating the effect of electrical stimulation on motor control. The reported outcomes were examined to identify a possible relationship between the reported effect and the following characteristics: duration of stimulation, method of stimulation, setting of stimulation parameters, target muscles and stage after stroke. RESULTS: Nineteen clinical trials were included, and the results of 22 patient groups were evaluated. A positive effect of electrical stimulation was reported for 13 patient groups. Positive results were more common when electrical stimulation was triggered by voluntary movement rather than when non-triggered electrical stimulation was used. There was no relation between the effect of electrical stimulation and the other characteristics examined. CONCLUSION: Triggered electrical stimulation may be more effective than non-triggered electrical stimulation in facilitating upper extremity motor recovery following stroke. It appears that the specific stimulus parameters may not be crucial in determining the effect of electrical stimulation.
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Aperonotus leptorhynchus (Gymnotiformes) produces wave-like electric organ discharges distinguished by a high degree of constancy. Transient frequency and amplitude modulations of these discharges occur both spontaneously and during social interactions, which can be mimicked by external electrical stimulation. The so-called chirps can be divided into four different types. Independent of the type of chirp produced under spontaneous conditions, the fish generate only significant numbers of type-2 chirps under evoked conditions. The rate of production of chirps of this type is largely determined by the frequency relative to the fish's frequency and signal intensity. Frequencies of + 10 Hz of the fish's own discharge frequency most effectively elicit chirps. Type-2 chirps can also be evoked through stimulation at or near the higher harmonic frequencies of the fish's frequency, but the chirp rate decreases with increasing number of the higher harmonic component. Over a certain range, the rate of production of type-2 chirps increases with increasing stimulus intensity. At very high intensities the generation of type-2 chirps is accompanied by the production of a novel type of electrical signal ("abrupt frequency rise") characterized by a frequency increase of approximately 20 Hz and high repetition rates of roughly 10 s(-1). We hypothesize that the different types of electric modulations subserve different behavioral functions.
Central thalamic electrical stimulation has been proposed as a method for remediation of acquired cognitive disability. Long-standing experimental and clinical observations indicate a key role for neurons within the central thalamus in maintaining the alert waking state and facilitating attended behaviors. Here, we show that continuous high frequency (100 Hz) electrical stimulation of the central thalamus generates widespread cortical activation of c-fos across all cortical layers and a selective pattern of regulation of zif268 within the supragranular, granular, and infragranular cortical laminae. Significant elevation of both immediate early genes also is seen in the dentate gyrus of the hippocampus. Use of the same stimulation parameters is shown to facilitate untrained goal-directed seeking behavior and object recognition memory in rodents. An overall increase of exploratory motor behaviors and grooming activity also is observed, consistent with a global increase in arousal. Taken together, these studies indicate that electrical stimulation of the central thalamus may enhance cognitive performance through neocortical and hippocampal neuronal activation and specific regulation of gene expression.