Electrical Stimulus Sensitivity

It also should be noted that the sensitivities of excitable cells to electric fields decrease rapidly as the electric stimulus is applied for time periods decreasingly short in comparison to the refractory period of the order of 1 msec. Hence, quotation of reported low frequency membrane sensitivities as done by Frey (35) carries no implication with regard to sensitivities claimed at microwave frequencies correspond to time periods of the order of 1 nsec, which is a million times smaller than the refractory period. More recently, it has been postulated (36) that microwave fields may well be perceived, provided they are modulated with frequencies below 10 or 20 Hz. This would be possible in principle if induced in situ fields and currents could be rectified with some degree of efficiency so that microwave fields would generate detectable low frequency currents. No evidence for such a mechanism has been demonstrated so far at the membrane level. 

On the other hand, the characteristics of detonation, electric spark sensitivity, and thermal decomposition correlate with the N NMR chemical shifts of nitrogen atoms of the most reactive nitro groups. The basis of initiation by electric spark could lie in a thermal stimulus [35,39,52,53]. However, thermal stimuli cannot be considered in the process of detonation initiation by shock (also by impact) [115]. This also agrees with the finding that the detonation characteristics of energetic materials correlate with the characteristics of their low-temperature decomposition, which means that the primary fragmentation of polynitro compounds in their detonation transformation proceeds at milder conditions than those present at the front of detonation wave or in its reaction zone. That also means that the detonation transformation itself of the given substance should be preceded by an induction period [120]. 

In recent years, ECT has been much improved. A muscle relaxant is given before treatment, which is done under brief anesthesia. Electrodes are placed at precise locations on the head to deliver electrical impulses. The stimulation causes a brief ( 30 seconds) seizure within the brain. The person receiving ECT does not consciously experience the electrical stimulus. For full therapeutic benefit, at least several sessions of ECT, typically given at the rate of three per week, are required. Electroconvulsive therapy appears to increase the sensitivity of postsynaptic 5-HT receptors and upregulation of 5-HTia postsynaptic receptors. 

Due to their sensitivity to electric stimulus, polyelectrolyte hydrogels have been investigated for their potential applications for electrically controlled drug delivery systems, electro-chemical actuators and sensors, as well as muscular actuators (Kaewpirom and Boonsang 2006). The set up for electrostimulation of... 

Electrochemical deposition of conjugated polymers occurs easily, but the final properties are sensitive to the deposition conditions, including supporting electrolyte, temperature, electrical stimulus (galva-nostatic, potentiostatic, or potentiodynamic), and electrode material. MEMS developers need to be familiar with how deposition conditions affect film properties, such as conductivity. Young s modulus, and speed. Further details on the effects of electropolymerization conditions on the structure and properties of conducting polymers can be found elsewhere [9]. 

The stimulus to evoke membrane channel currents can be electrical, chemical, luminous or mechanical. An example of the mechanical stimulus is given in the stretch-activated channels, where it consists of the pressure applied to the recording pipette. The luminous stimulation that generates electrical responses on photoreceptors, is done with the appropriate optical set-up. In the case of chemical stimulation, the substances that will interact with channels can be applied in different ways. If the time-course of the response is not important, the chemical stimulation can be obtained simply by the perfusion of the experimental chamber. When the chemical stimulation has to be applied transiently pressure ejection microperfusion or iontophoresis can be used [16]. The stimulation can be driven by an electrical signal, in order to have a triggering signal to study the time behavior of the responses. In any case, an electrical stimulus is also required, not only to analyze voltage-sensitive channels, but also to monitor the electrical characteristics of the patch, as will be shown in section 4. 

A serious drawback of naturalistic observations and simple one- and two-choice tests is that these methods depend on untrained responding. Simply because an animal fails to respond is not evidence that it has failed to detect a stimulus. For this reason, training procedures have been developed. Typically, these methods employ classical or operant conditioning. With the former, the presentation of a stimulus is paired with the delivery of a reinforcer. For example, presentation of an odor is paired with the delivery of electric shock. The shock leads to an unconditioned increase in heart rate or a measurable change in some other physiological response. After several pairings, presentations of odor alone lead to conditional or conditioned increases in heart rate. The concentration of the odor stimulus can then be manipulated, and questions can be asked about minimum detectable concentrations etc. Not infrequently, greater stimulus sensitivities are measured when trained animals are used than when data are collected from untrained animals in simple choice tests. 

As noted above, Passmore et al. (2003) were the first to demonstrate that Kv7.2, 7.3 and 7.5 are expressed at the protein level in sensory neurons and also that functional M-currents can be measured under voltage-clamp. They were further able to demonstrate that pharmacological activation of Kv7 channels by direct application of retigabine to the spinal cord inhibited both C fiber and AS fiber-mediated signaling. This was true when the afferent fibers were excited by either electrical or tactile stimuli. Moreover, wind-up , an increased sensitivity of the stimulus/response relationship to repetitive stimuli, is also inhibited. These results demonstrate a clear role of Kv7 channels in sensory neuron processing. Gerlach et al. (2006, 2007) have also reported direct effects of ICA-27243 on both M-currents and membrane potential in isolated DRG neurons. Activation of the M-current by ICA-27243... 

Cocaine was, and still is, in the focus of investigations.24-27,29-39 Amongst others, the mechanism of acute cocaine intoxication,24 behavioural sensitization,25 the effects of electric shock on responding, when maintained by cocaine,26 its effects in sleep-deprived humans,27 and the discriminative stimulus properties of cocaine, norcocaine, and A-allylnorcocaine32 have been studied. The effect of benzotropine mesylate on the prolactin response to haloperidol was observed.28... 

A device used as a primary stimulus component in all explosive or pyrotechnic devices, such as detonator primer or squib, which, on receipt of proper mechanical or electrical impulse, produces burning or detonating action. Generally contains a small quantity of sensitive explosive (-> Squib -> Detonator -> Primer -> Bullet Hit Squib). 

The human inner ear is embedded in the temporal bone and houses the sensory epithelia of the cochlea and vestibular apparatus (Fig. 1). The sensory epithelia contain hair cells which transduce the stimulus of sound or motion into nerve impulses. Hair cells are equipped with an apical mechano-sensitive apparatus made up by three rows of actin-containing stereocilia of increasing length. Displacement of the stereocilia towards the longest row opens (gates) mechano-electrical transduction channels, whereas deflection into the opposing direction closes the channels [12],... 

Copper is particularly incompatible with lead azide because the very sensitive copper azide forms in the presence of even small percentages of adsorbed moisture [20,21]. The copper azide appears as a black tarnish on the copper or copper-bearing surface. The film is very sensitive to electric, impact, and fnc-tional stimulus. 

One of the ways of specification of this mechanism can lie in study of relationships of the said sensitivity of energetic materials to their molecular structure [32], thermal reactivity [35,39,52,109-111], sensitivity to mechanic stimuli [32,109,112,113] and detonation characteristics [5,33,34,47]. As already stated, a thermal stimulus could be the basis of electric spark initiation [35,39,52,53],... 

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