Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ELECTRICITY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources
PubMed2005

Effect of centrifugation and electrical activation on male pronucleus formation and embryonic development of porcine oocytes reconstructed with intracytoplasmic sperm injection.

Oocyte centrifugation and electrical activation are commonly used in intracytoplasmic sperm injection (ICSI) of bovine and porcine oocytes, to facilitate visual identification of sperm release into the ooplasm and to support oocyte activation following injection with tail membrane-damaged sperm. The present study evaluated the necessity of these steps in porcine modified ICSI. In the first series of experiments, in vitro-matured gilt oocytes with or without centrifugation were injected with head membrane-damaged spermatozoa aspirated tail first. Oocytes without centrifugation exhibited a significantly higher normal fertilisation rate, defined as male pronucleus (MPN) and female pronucleus (FPN) formation and the presence of two polar bodies, than centrifuged oocytes (40% v. 9%, respectively; P < 0.05). The rate of MPN formation was significantly higher in uncentrifuged oocytes compared with centrifuged oocytes (48% v. 17%, respectively; P < 0.05). The rates of survival, cleavage, blastocyst formation and total cell number in blastocysts did not differ between the two groups of oocytes. Next, the effect of electrical activation after ICSI on uncentrifuged oocytes injected with head membrane-damaged spermatozoa was determined. No significant differences were observed in the rate of MPN formation in sperm-injected oocytes regardless of electrical activation. However, the survival rates of sperm-injected or control oocytes without electrical activation were significantly higher than those of sperm-injected or control oocytes with electrical activation (88% and 84% v. 77% and 64%, respectively; P < 0.05). The cleavage rates of sperm-injected oocytes were significantly higher than those of control oocytes, regardless of electrical activation (77% and 81% v. 47% and 61% in sperm-injected and control oocytes with or without electrical activation, respectively; P < 0.05). Although development to blastocysts was similar in all experimental groups, the total cell numbers in blastocysts from control oocytes were significantly higher than those in sperm-injected oocytes, regardless of electrical activation (40 and 44 v. 22 and 26 in control and sperm-injected oocytes with or without electrical activation, respectively; P < 0.05). In conclusion, the present study clearly demonstrated that oocyte centrifugation before sperm injection is not beneficial to normal fertilisation and that electrical activation is not necessary in the modified porcine ICSI.

Animals↗
PubMed2005

Relation between stimulation characteristics and clinical outcome in studies using electrical stimulation to improve motor control of the upper extremity in stroke.

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.

Arm↗
PubMed1999

Effect of the duration of electrical stimulation on the analgesic response in patients with low back pain.

BACKGROUND: Electrical stimulation of peripheral nerves produces acute analgesic effects. This randomized, sham-controlled, crossover study was designed to evaluate the effect of differing durations of electrical stimulation on the analgesic response to percutaneous electrical nerve stimulation in 75 consenting patients with low back pain. METHODS: All patients received electrical stimulation for four different time intervals (0, 15, 30, and 45 min) in a random sequence over the course of an 11-week study period. All active percutaneous electrical nerve stimulation treatments were administered using alternating frequencies of 15 and 30 Hz three times per week for 2 consecutive weeks. The prestudy assessments included the health status survey short form questionnaire and 10-cm visual analog scale scores for pain, physical activity, and quality of sleep, with 0 being the best and 10 being the worst. The pain scoring was repeated 5-10 min after each 60-min study session and 24 h after the last treatment session with each of the four methods. The daily oral analgesic requirements were assessed during each of the four treatment blocks. At the end of each 2-week treatment block, the questionnaire was repeated. RESULTS: Electrical stimulation using percutaneously placed needles produced short-term improvements in the visual analog scale pain, physical activity, and quality of sleep scores, and a reduction in the oral analgesic requirements. The 30-min and 45-min durations of electrical stimulation produced similar hypoalgesic effects (48+/-21% and 46+/-19%, respectively) and were significantly more effective than either 15 min (21+/-17%) or 0 min (10+/-11%). The 30- and 45-min treatments were also more effective in improving physical activity and sleep scores over the course of the 2-week treatment period. In contrast to the sham treatment (0 min), the health status survey short form revealed that electrical stimulation for 15 to 45 min three times per week for 2 weeks improved patient function. CONCLUSION: The recommended duration of electrical stimulation with percutaneous electrical nerve stimulation therapy is 30 min.

Adult↗
PubMedDate not supplied

Auditory and neuropsychiatric behavior patterns after electrical injury.

Major electrical injury causes widespread tissue destruction. Slow and incomplete functional recovery after electrocution-type injury has led clinicians to suspect residual brain damage. One hundred and one consecutive patients who were admitted to the hospital because of electrical injury were studied. Forty-eight had electric-current injury. The other 53 had flash, contact, or arcing burns (electrical injury without passage of current). A primary study cohort of 16 patients with electric-current injury and 18 patients who had electrical injury without passage of current received specialized trauma-based psychiatric treatment, which was coordinated with serial auditory and neurologic studies. This strategy served to highlight discrepancies between preinjury and postinjury performance. Twelve of 16 patients with electric-current injury showed neurobehavioral (organic) dysfunction after 1 year, which implied brain damage; eight showed persistent auditory changes. Four of 18 patients who had electrical injury without passage of current met criteria for post-traumatic stress disorder after 1 year; none had neurobehavioral or auditory dysfunction. These findings indicate that patients with electric-current injury are at risk for permanent auditory dysfunction and brain damage, whereas those with other types of electrical burns are not.

Adult↗
PubMed2002

Electrical conductivity of lumbar anulus fibrosis: effects of porosity and fixed charge density.

STUDY DESIGN: Experimental investigation of the electrical conductivity of normal and trypsin-treated lumbar anulus fibrosis specimens. OBJECTIVES: To measure the electrical conductivity of intervertebral disc tissues and to study the effects of tissue porosity (volume fraction of water) and fixed charge density on the electrical conductivity of anulus fibrosis in physiologic saline. SUMMARY OF BACKGROUND DATA: Specific electrical conductivity is one of the material properties of intervertebral discs. Their value depends on ion concentrations and ion diffusivities within the tissue, which in turn are functions of tissue composition and structure. To our knowledge, the electrical conductivity of intervertebral discs has not been studied. Investigation of the electrical conductivity of intervertebral discs and understanding of their relationship to tissue porosity and fixed charge density will provide insights into electromechanical phenomena (e.g., streaming potential) and ion transport in intervertebral discs. METHODS: A total of 35 porcine lumbar anulus fibrosis specimens were divided into two groups: one control group (n = 10) and one trypsin-treated group (n = 25). The specimens in the control group were subjected to one-dimensional free swelling in phosphate-buffered saline (pH 7.4), and electrical conductivity and porosity (water content) were measured over a period of about 45 minutes. The specimens in the treated group were immersed in a trypsin solution (372 U/mL phosphate-buffered saline) for 45 minutes at room temperature, and the electrical conductivity and porosity were measured after treatment. The electrical conductivity was correlated to tissue porosity for the control and treated specimens. The influences of porosity and fixed charge density were studied. RESULTS: The average value for control specimens was 5.60 +/- 0.89 mS/cm (mean +/- SD; n = 10) before swelling and 9.11 +/- 0.90 mS/cm (mean +/- SD; n = 10) after swelling. Tissue porosity increased from 0.74 +/- 0.03 (mean +/- SD; n = 10) before swelling to 0.83 +/- 0.02 (mean +/- SD; n = 10) after swelling. The trypsin treatment reduced anulus fibrosis porosity by 3.6% (P < 0.05) and conductivity by 13% (P < 0.05) compared to those for control specimens after swelling. No significant changes werefound in wet and dry tissue densities between control and treated groups. There was a significant, linear correlation between conductivity and porosity for control anulus fibrosis specimens (R2 = 0.87; 86 measurements). CONCLUSIONS: Measured electrical conductivity was sensitive to tissue porosity, but not to fixed charged density for anulus fibrosis specimens in phosphate-buffered saline.

Animals↗
PubMed1999

A clinical analysis of 836 cases with electric injury.

Eight hundred thirty-six patients with electric injury were admitted to Shanghai Power Hospital from 1972 to 1998. The majority of electric injury patients were young or middle-aged industrial workers from both cities and rural areas. These patients were classified into three categories depending on the type of electric injury: (1) electric shock; (2) electric contact burn injury; (3) electric arc burn. In our study of wound management, we focused on three areas: first, the choice of operation time in electric burn injury; second, the methods of wound management on the injured extremities, especially the hands and upper limbs; third, functional site wounds that included some exposed blood vessels. Nerves and tendons were covered and repaired by various flaps. Through the analysis of 836 electric injury cases, we summarized our experience of treating electric injury with the purpose of increasing our knowledge in the area of electric injury prevention and treatment.

Accidents, Occupational↗
PubMed2001

Electrical storm presages nonsudden death: the antiarrhythmics versus implantable defibrillators (AVID) trial.

BACKGROUND: Electrical storm, multiple temporally related episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF), is a frequent problem among recipients of implantable cardioverter defibrillators (ICDs). However, insufficient data exist regarding its prognostic significance. METHODS AND RESULTS: This analysis includes 457 patients who received an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial and who were followed for 31 +/- 13 months. Electrical storm was defined as > or = 3 separate episodes of VT/VF within 24 hours. Characteristics and survival of patients surviving electrical storm (n = 90), those with VT/VF unrelated to electrical storm (n = 184), and the remaining patients (n = 183) were compared. The 3 groups differed in terms of ejection fraction, index arrhythmia, revascularization status, and baseline medication use. Survival was evaluated using time-dependent Cox modeling. Electrical storm occurred 9.2 +/- 11.5 months after ICD implantation, and most episodes (86%) were due to VT. Electrical storm was a significant risk factor for subsequent death, independent of ejection fraction and other prognostic variables (relative risk [RR], 2.4; 95% confidence interval [CI], 1.3 to 4.2; P = 0.003), but VT/VF unrelated to electrical storm was not (RR, 1.0; 95% CI, 0.6 to 1.7; P = 0.9). The risk of death was greatest 3 months after electrical storm (RR, 5.4; 95% Cl, 2.4 to 12.3; P = 0.0001) and diminished beyond this time (RR, 1.9; 95% CI, 1.0 to 3.6; P=0.04). CONCLUSIONS: Electrical storm is an important, independent marker for subsequent death among ICD recipients, particularly in the first 3 months after its occurrence. However, the development of VT/VF unrelated to electrical storm does not seem to be associated with an increased risk of subsequent death.

Aged↗
PubMed1988

Electrical stimulation of ascending noradrenergic tracts in the midbrain: suppression of steroid-induced luteinizing hormone release.

This study examined the effects of electrical stimulation of the dorsal and ventral ascending noradrenergic tracts in the central nervous system [dorsal (DNT) and ventral (VNT) noradrenergic tracts] during an ongoing LH surge induced by ovarian steroids. A bipolar electrode was implanted in the midbrain of ovariectomized rats, in the region of either the DNT or VNT. One week later the rats were given estradiol benzoate (10 micrograms/100 g BW), followed 3 days later by an injection of progesterone (2 mg) at 1100 h. This steroid treatment resulted in a LH surge in the afternoon which peaked at approximately 1800 h. Biphasic electrical stimulation (50-100 microA; 400 musec; 30 Hz) was applied to the conscious unrestrained rats for 1 h beginning at 1600 h. Electrical stimulation of the DNA (n = 10) for 1 h resulted in significantly lower LH levels at 1700 h. Similar electrical stimulation of the VNT (n = 8) also markedly suppressed LH release at 1700 h. Electrical stimulation of brain sites close to but outside the DNT or VNT were ineffective. After the cessation of electrical stimulation, LH levels began to rise again and at 1900 h were not significantly different from levels in the control rats. To determine if the recovering LH surge could be interrupted further, the effects of a second electrical stimulating session, 2 h after the first one, was investigated in other groups of animals. As expected, electrical stimulation of either the DNT or VNT between 1600 and 1700 h resulted in a transient suppression of the steroid-induced LH surge. The mean LH levels of these animals were on the rise between 1700 and 1900 h. Dramatically, a second electrical stimulation applied to the DNT or VNT from 1900-2000 h again inhibited LH release. Thus, the LH release pattern in these twice-stimulated rats was significantly different from that in either the nonstimulated controls or animals that had received only one electrical stimulation session (at 1600 h). Treatment of the rats with an alpha-adrenergic blocker (phenoxybenzamine) reversed the inhibitory effect of DNT activation on the LH surge. Treatment with a beta-adrenergic blocker (propranolol) or a dopamine antagonist (pimozide) was ineffective. These data demonstrate that, similar to intraventricular infusion of norepinephrine, activation of the ascending norepinephrine fibers results in interruption of the steroid-induced LH surge.

Animals↗
PubMed2006

Response of gait deficits to neuromuscular electrical stimulation for stroke survivors.

Persistent gait deficits after stroke can cause falls, elevated energy cost and poor endurance. Coordination impairment is an underlying cause of gait deficits. Few efficacious interventions have been described that have targeted and measured restoration of coordinated gait components. Neuromuscular electrical stimulation can provide the critical gait practice characteristic of close-to-normal movements, by electrically inducing muscle contractions and coordinated movements that are not possible under volitional effort. Two-channel, surface neuromuscular electrical stimulation can be synchronized with phases of gait and can provide faster, more symmetrical neuromuscular electrical stimulation-assisted gait than gait with no neuromuscular electrical stimulation. Difficulties encountered during the use of surface neuromuscular electrical stimulation for gait training led to the development of neuromuscular electrical stimulation with implanted technologies. Implanted electrodes and/or stimulators proved to be feasible for gait training in stroke survivors. Gait training with a multichannel neuromuscular electrical stimulation system with implanted electrodes proved more advantageous than gait training without neuromuscular electrical stimulation, according to measures of volitional coordinated gait components (neuromuscular electrical stimulation deactivated).

Electric Stimulation Therapy↗
PubMed2002

[Injury by electrical forces: pathophysiology, biophysics and pathogenesis].

As the technologic sophistication of generation and distribution of electrical energy has grown, so has the general concern about the effects of electric fields on human health. There can be no doubt that the significance of electrical trauma will continue to grow with our increasing use of power. It is apparent that our understanding of the various forms of electric trauma must increase, while we continue to promote safety near electrical hazards and develop effective medical therapies. Tissue damage as a result of electrical injury occurs by two mechanisms which are summative in action and have a variable degree of contribute to the ultimate damage produced. Thermal tissue damage occurs as a result of heat generated within the tissue (which offer an electrical resistance) secondary to the passage of the electrical current. High temperatures can also lead to cell membrane components, e.g., phospholipids, to dissolve. Electroportation damage is the tissue damage induced secondary to the strong electric field. Transmembrane potentials caused by electrical current result in the formation of pore in the phospholipid component of the cell membrane resulting in loss of function of the cell membrane with consequent cell death.

Animals↗
PubMed2003

[Clinical analysis of brain injury in patients injured by high voltage electricity].

OBJECTIVE: To explore the pathogenic characteristics and management of brain injury in patients injured by high voltage electricity. METHODS: One hundred and thirty eight patients injured by electricity were enrolled in this study. Postburn brain injury was diagnosed by clinical sighs and imaging analysis. The brain injury was graded as mild, moderate, severe and most severe. The relationships among the inlet of the electric current and the electric voltage and the degree of brain injury were analyzed, and the causes and pathogenesis of the brain injury were suggested. Treatment modality was optimized for the patients according to the diagnostic data. RESULTS: In this group of patients, brain injury was identified in 106 cases, mostly rated as mild and moderate. Only 4 cases were ranked as severe degree with positive imaging findings. The electric voltage seemed to be not correlated with the incidence of postburn brain injury. But the intensity of electric current and the locations of electrical current inlet and outlet were closely related to the degree of brain injury. Among all the patients in this group, 131 survived and 7 died after treatment. But there was no death due directly to brain injury. CONCLUSION: There was high incidence of postburn brain injury in patients injured by high voltage electricity. The injury might be related to the direct effect of electrical current on the brain tissue, to mechanical injury, to the cardio-pulmonary lesions caused by electrical current, or to massive skin burn. Early and accurate diagnosis of the injury was of key importance for lowering both mortality and disability.

Adolescent↗
PubMed1992

[A physiological investigation of chronic electrical stimulation with scala tympani electrodes in kittens].

A physiological investigation of cochlear electrical stimulation was undertaken in six two-month-old kittens. The scala tympani electrodes were implanted and electrically stimulated using biphasic balanced electrical pulses for periods of 1000-1500h in four ears. Four ears received implants for same period but without electrical stimulation. The other two ears served as normal control. The results indicated: 1) Chronic electrical stimulation of the cochlea within electrochemically safe limits did not influence the hearing of kittens and the normal delivery of impulses evoked by acoustic and electrical signals on the auditory brainstem pathway. 2) The wave shapes of EABRs were similar to those of ABRs. The amplitudes of EABRs showed a significant increase following chronic electrical stimulation, resulting in a leftward shift in the input/output function. The absolute latencies and interwave latencies of waves II-III, III-IV and II-IV were significantly shorter than those of ABRs. These results imply that there was no adverse effect of chronic electrical stimulation on the maturing auditory systems of kittens using these electrical parameters and the mechanism of electrical hearing should be further studied.

Animals↗
PubMed1983

Amphetamine inhibits the electrically evoked release of [3H]dopamine from slices of the rabbit caudate.

The effects of d-amphetamine on the spontaneous and electrically evoked release of [3H]dopamine in slices of the rabbit caudate nucleus were investigated. At a concentration of 0.1 microM amphetamine did not modify the spontaneous outflow of radioactivity, but significantly inhibited the release of [3H]dopamine elicited by electrical stimulation. At a 10-fold higher concentration (1 microM) amphetamine enhanced the spontaneous outflow of radioactivity and also inhibited the stimulation-evoked release of [3H]dopamine. The inhibition by amphetamine of electrically evoked release of [3H]dopamine was also observed under conditions in which monoamine oxidase was inhibited by pargyline. At concentrations of 0.1 and 0.5 microM amphetamine there was no inhibition of neuronal uptake and retention of [3H]dopamine in slices of the rabbit caudate. In the presence of 100 microM l-3-iodotyrosine, the inhibition by amphetamine of [3H]dopamine release was still obtained. The dopamine receptor antagonists, haloperidol and sulpiride, were not able to antagonize the inhibition by amphetamine of the electrically evoked release of [3H] dopamine at concentrations which effectively blocked apomorphine-induced inhibition of stimulation-evoked release of the labeled neurotransmitter. Exposure to serotonin in the presence of an inhibitor of neuronal uptake did not modify the spontaneous outflow of radioactivity or the electrically evoked release of [3H] dopamine. Nomifensine, an inhibitor of neuronal uptake of dopamine prevented the release of [3H]dopamine induced by exposure to 10 microM amphetamine and antagonized the inhibitory effects of lower concentrations of amphetamine on the electrically evoked release of [3H]dopamine. Tyramine and amfonelic acid in low concentrations enhanced the spontaneous outflow of radioactivity and, similarly to amphetamine, inhibited the electrically evoked release of [3H]dopamine. Exposure to bretylium (1 and 10 microM) inhibited the release of [3H]dopamine elicited by electrical stimulation. In the presence of bretylium, the inhibition by amphetamine of the stimulation-evoked release of [3H]dopamine was still present. In contrast to its inhibitory action on the release of [3H]dopamine, exposure to amphetamine (0.1-1.0 microM) enhanced in a concentration-dependent manner the electrically evoked release of [3H]norepinephrine from the rabbit hypothalamus. These results indicate that the inhibition by amphetamine of the electrically evoked release of [3H]dopamine does not involve the activation of presynaptic inhibitory dopamine autoreceptors possibly located on dopaminergic nerve terminals.(ABSTRACT TRUNCATED AT 400 WORDS)

Amphetamine↗
PubMed1993

Electrical resonance of isolated hair cells does not account for acoustic tuning in the free-standing region of the alligator lizard's cochlea.

The cochlea of the alligator lizard is divided into two morphologically and physiologically distinct regions. In the "tectorial region," hair bundles of hair cells are draped by a tectorial membrane, whereas in the "free-standing region," hair bundles are said to be free-standing because there are no overlying tectorial structures. The acoustic tuning of the free-standing region depends at least in part on mechanical resonances of the hair bundles. In the turtle cochlea, in contrast, acoustic tuning depends in large part upon the electrical properties of the hair cells. We have investigated the electrical properties of hair cells isolated from the free-standing region of the alligator lizard's cochlea. When injected with steps of depolarizing current, these "free-standing hair cells" exhibited electrical resonances that were comparable in frequency and quality to electrical resonances in cochlear hair cells from turtles, chicks, and alligators, and in saccular hair cells from frogs and fish. In the lizard's free-standing hair cells, however, the electrical resonance frequencies (< 300 Hz) were a decade below the cells' acoustic characteristic frequencies (between 1 and 4 kHz), showing that the electrical resonance is not likely to contribute to acoustic tuning. The electrical resonances were not apparent at rest. The cells' resting potentials were significantly more negative than the activation voltage (approximately -40 mV) of the Ca(2+)-dependent K+ current upon which the electrical resonance has been shown to depend in other hair cells. At potentials more negative than -50 mV, an inwardly rectifying K+ conductance dominated. Because we observed no electrical tuning above 300 Hz, our results indirectly support a mechanical origin for acoustic tuning in the free-standing region of the alligator lizard cochlea. These results further show that acoustic tuning cannot be inferred solely from the electrical resonances of isolated hair cells.

Animals↗
PubMed1989

Growth and electric current loops in plants.

A theory is presented for a relationship between ion accumulation and electric current loops in multicellular systems such as the roots and stems of higher plants. A network of electric circuits shows that the electric current transported across the cell membrane flows between an elongating region and a mature region, not only in roots but also in stems. In roots, ions constituting the extracellular electric current flow in the external aqueous medium, while in stems an electric current of comparable density flows within the epidermal cell wall. Based on this theoretical result, electric isolation between the elongating and mature regions was made in the case of both roots and stems. The speed of growth during the initial stage was greatly decreased due to a change in the distribution of protons around the surfaces of the plant by cutting off the electric current loop. Electrochemical calculation shows that ions are not always accumulated at the efflux site, since the ion distribution is strongly affected by the relation of the magnitudes between the electric field and electric current. The results calculated for the electric potential and pH distributions around the root agree with experimental data.

Journal Article↗
PubMed2002

Semiochemicals released by electrically stimulated red imported fire ants, Solenopsis invicta.

The red imported fire ant Solenopsis invicta Buren, has evolved sophisticated chemical communication systems that regulate the activities of the colony. Among these are recruitment pheromones that effectively attract and stimulate workers to follow a trail to food or alternative nesting sites. Alarm pheromones alert, activate, and attract workers to intruders or other disturbances. The attraction and accumulation of fire ant workers in electrical equipment may be explained by their release of pheromones that draw additional worker ants into the electrical contacts. We used chemical analysis and behavioral bioassays to investigate if semiochemicals were released by electrically shocked fire ants. Workers were subjected to a 120 V, alternating-current power source. In all cases, electrically stimulated workers released venom alkaloids as revealed by gas chromatography. We also demonstrated the release of alarm pheromones and recruitment pheromones that elicited attraction and orientation. Arrestant behavior was observed with the workers not electrically stimulated but near those that were, indicating release of unkown behavior-modifying substances from the electrically stimulated ants. It appears that fire ants respond to electrical stimulus by generally releasing exocrine gland products. The behaviors associated with these products support the hypothesis that the accumulation of fire ants in electrical equipment is the result of a foraging worker finding and closing electrical contacts, then releasing exocrine gland products that attract other workers to the site, who in turn are electrically stimulated.

Animal Communication↗
PubMed1994

Neuronal responses in cat primary auditory cortex to electrical cochlear stimulation. I. Intensity dependence of firing rate and response latency.

1. Responses of neurons in primary auditory cortex (AI) of the barbiturate anesthetized adult cat were studied using cochlear stimulation with electrical and acoustic stimuli. Acoustic stimulation of the ear ipsilateral to the studied cortical hemisphere with brief biphasic clicks was compared with electrical stimulation of the contralateral cochlea with brief biphasic electrical pulses delivered via a feline cochlear prosthesis. The contralateral ear was deafened immediately before implantation of the cochlear prosthesis. The feline cochlear prosthesis consisted of four bipolar electrode pairs and was placed in the scala tympani. Two bipolar electrode conditions were used for stimulation: one near radial pair with electrode spacing of approximately 0.5 mm, and one longitudinal pair with electrode spacing of approximately 6 mm. 2. The firing rates obtained from single- and multiple-neuron recordings were measured as a function of stimulus intensity for single electrical and acoustic pulses. Resulting rate/level functions were characterized by a fast growing low-level segment and a more slowly growing, saturating, or decreasing high-level segment. The slopes of these two segments as well as the stimulus level and firing rate at the juncture of these two segments (the transition point) provide a complete characterization of the response magnitude behavior as a function of stimulus intensity. 3. The main characteristics of rate/level functions obtained with electrical and acoustic cochlear stimulation were quite similar. However, for any given neuron, differences in the primary growth behavior, such as monotonic or nonmonotonic growth, could be observed between the different stimulation modes. 4. Response latencies from single- and multiple-neuron recordings were obtained as a function of stimulus intensity for electrical and acoustic pulses. Resulting latency/level functions were characterized by a rapidly decreasing low-level segment and a more slowly decreasing high-level segment. The slopes of these two segments as well as the stimulus level and response latency at the juncture of these two segments (the transition point) provide a complete characterization of the response latency behavior as a function of stimulus intensity. Transition point levels for the rate/level function and the latency/level were nearly identical. 5. The characteristic latency behavior for each neuronal response was found to be very similar for acoustic and electrical stimulation. Correlation analysis revealed a close relationship between latency parameters of the two electrical stimulation conditions, a weaker relationship between the longitudinal electrical and the acoustic conditions, and the weakest relationship between the radial electrical and acoustic conditions. 6. Correlation analysis for rate and latency parameters revealed several relationships between these response aspects.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1994

[Effects of electromagnetic field emitted by electric blankets on brain catecholamine in fetal mice].

A study of effects of electromagnetic field emitted by electric blankets on brain catecholamine (CA) content in fetal mice under development was carried out, to determine which component of the electromagnetic field, electric field or magnetic field or both, causes the effects, and to improve the design of the electric blankets. Forty-eight NIH pregnant mice were divided into three groups exposed to electric field, magnetic field and electromagnetic field, respectively for five hours daily during mice's whole gestational periods, and one control group. Twelve infant mice in each group were decapitated at the seventh day after delivery, and sagittal sections of the middle part of their brain were prepared for quantitative histofluorescence analysis of CA with a microspectrophotometer. Results showed brain CA content in all the exposed groups was lower than that in controls, with F values of 18.5 and 37.6 in hypothalamus and hippocampus, respectively. Both electric and magnetic fields could decrease brain CA content in mice, but electric fields had greater effects. It suggested the focus in production of electric blankets should be put on reducing electric field, as well as reducing magnetic field by cloth wiring design. Electric field lowered to less than 100 V/m for the electric blankets with such design from 1 kV/m, and magnetic field to less than 0.08 microT from 1 microT.

Animals↗