Neural pulse

The nature of the signal processing, and its potential effectiveness, depends on the characteristics of the auditory system. The ear transforms the incoming acoustic signal into mechanical motion, and this motion ultimately triggers neural pulses that carry the auditory information to the brain. The essential components of the ear are shown in Fig 6.1. 

The tectorial membrane rests at the top of the organ of Corti, and the basilar membrane forms the base. Two types of hair cells are found along the basilar membrane. There are three rows of outer hair cells and one row of inner hair cells. The outer hair cells form part of the mechanical system of the cochlear partition, while the inner hair cells provide transduction from mechanical motion into neural firing patterns. There are about 30,000 nerve fibers in the human ear. The vast majority are afferent fibers that conduct the inner hair cell neural pulses towards the brain approximately 20 fibers are connected to each of the 1,500 inner hair cells. Approximately 1,800 efferent fibers conduct neural pulses from the brain to the outer hair cells [Pickles, 1988],... 

Although it is common to assert that there are only four distinct taste sensations, even a casual introspection reveals that other oral sensations can be distinguished. As one may expect, flavor chemists have discovered that many separate oral sensations are required to reconstruct the flavors of foods and beverages. Some of these sensations have distinct oral loci from which they are elicited by specified types of chemical compounds, thus indicating that different neural systems are involved. Many of these sensations are difficult to typify verbally and also often have affective overtones. These sensations are the result of considerable peripheral and central neural processing and are only indirectly related to the peripheral neural pulse signals as discussed above. The type of sensation elicited and the locus of elicitation provide us with further measures of the functional properties of oral chemoreceptor systems. 

What is more interesting, at least from the theoretical point of view is that oscillatory behaviour might emerge as a result of the interaction between the system and the external noise applied. This phenomenon was earlier described in a radio-engineering context (Kuznetsov et ai, 1965). Studying the role of multiplicative coloured noise for the catalytic oxidation of CO on a platinum surface, de la Rubia et ai (1982) demonstrated that a limit cycle is induced by external noise. Similarly, Treutlein Schulten (1985) found noise induced limit cycles in the Bonhoffer-van der Pol model of neural pulses (see further Lefever Turner (1984)). 

Treutlein, M. Schulten, K. 1985. Noise-induced limit cycle on the bonhoffer-Van der Pol model of neural pulses. Ber. Bunsenges. Phys. Chem., 89, 710-19. 

M. Schweizer-Berberich, M. Zdralek, U. Weimar, W. Gopel, T. Viard, D. Martinez, A. Seube, and A. Peyre-Lavigne. Pulsed mode of operation and artificial neural network evaluation for improving the CO selectivity of Sn02 gas sensors . Sensors and Actuators B65 (2000), 91-93. 

It is noteworthy that some therapeutic applications, such as transcutaneous electrical neural stimulation, involve application to the skin of electric pulses of up to hundreds of volts [5], However, a safety limitation is the major concern associated with the use of electroporation, even though several reports indicated that the damage to the skin was mild and reversible [16,23]. The only skin alteration seen with electroporation was slight erythema that decreased within a few hours [34]. Patients submitted to electrochemotherapy seemed to tolerate well the application of 10,000 V/cm for 100 p,s square-wave pulses [35]. However, to avoid pain during electroporation, milder conditions such as lower voltage, shorter pulses, or improved electrode design could be used [36]. 

A consortium of 13 technical and medical partners works on different tasks to develop a complete system for a visual prosthesis (Fig. 25). The neural pros-theses comprises a unit to record and process ambiance light, an encoder that transforms visual information into a sequence of stimulation pulses, a micro-electromechanical system that is implanted into the eye for interfacing the retina and for generating the appropriate stimuli. 

Probably, a combination of both i) digitally recording of LSC pulses plus their analysis by a neural network and ii) reducing the amount of reaction products entering the SISAK system with a pre-separator gives the most promising perspective. Various liquid-liquid extraction schemes for the transactinides have already been elaborated. An example is the separation procedure proposed for liquid-phase studies of element 107, bohrium (Bh) [62],... 

Microelectrodes made of carbon have been used for in vivo neuroelectrochemistry to measure catecholamines in neural tissues [137]. A major technical issue is distinguishing one compound from another using redox potential as a basis and differential pulse voltammetry as the method. 

Aberg, K.M. and Jacobsson, S.P. (2001) Preprocessing of three-way data by pulse-coupled neural networks - an imaging approach. Che-mom. Intdl. Lab. Syst., 57, 25-36. 

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