Neurons analogy

There has been a steady development of neuronal analogs over the past 50 years. An important early model was proposed in 1943 by McCulloch and Pitts [23]. They described the neuron as a logical processing unit, and the influence of their model set the mathematical tone of what is being done today. Adaption or learning is a major focus of neural net research. The development of a learning rule that could be used for neural models was pioneered by Hebb, who proposed the famous Hebbian model for synaptic modification [24]. Since then, many alternative quantitative interpretations of synaptic modification have been developed [15-22]. 

Serotonergic neurons. Analogous enzymes, transport pumps, and receptors exist in the 5HT neuron (Figs. 5 — 34 through 5—42). For synthesis of serotonin in serotonergic... 

Only after the amount of data has been reduced to conform to the conveyance limits of neurons are the signals converted to digital form. Myelinated neurons can transmit action potentials faster than slower unmyelinated neurons. Thus, in any given amount of time, more information can be conveyed on a myelinated neuron. Analog processing either limits the amount of information to the rate at which it can be transmitted, or additional information is lost. 

In a series of experiments that correspond remarkably well with the electrically coupled neuron analogy, Crowley and Field (1986) studied the BZ reaction in two CSTRs, using the difference in redox potential between the two reactors to determine the amount of current that flows from one to the other. They obtained a wealth of dynamical behavior, including entrainment, quasiperiodicity, and chaos. In this study, as in all other physical coupling experiments to date, the same reaction is run in all of the subsystems. 

The presence of polymer, solvent, and ionic components in conducting polymers reminds one of the composition of the materials chosen by nature to produce muscles, neurons, and skin in living creatures. We will describe here some devices ready for commercial applications, such as artificial muscles, smart windows, or smart membranes other industrial products such as polymeric batteries or smart mirrors and processes and devices under development, such as biocompatible nervous system interfaces, smart membranes, and electron-ion transducers, all of them based on the electrochemical behavior of electrodes that are three dimensional at the molecular level. During the discussion we will emphasize the analogies between these electrochemical systems and analogous biological systems. Our aim is to introduce an electrochemistry for conducting polymers, and by extension, for any electrodic process where the structure of the electrode is taken into account. 

The possibility that an aetive metabolite is involved in the neurotoxic effects of amphetamine analogs reeeives limited discussion in this chapter and has been considered previously, espeeially with />-chloroamphetamine (Miller et al. 1986.) Partly beeause the ehemieal structures of these amphetamines do not suggest ways in whieh they would be toxic to neurons, the... 

A fourth approach to evaluating the intactness of dopamine and/or serotonin neurons in human subjects who have taken one of the amphetamine analogs might be to use a probe for labeling a constituent of those neurons in position emission tomography scanning studies. A label for the serotonin or dopamine uptake carrier, or a label for tryptophan hydroxylase or tyrosine... 

The most promising mechanism of action, which may account for some of caffeine s potential ergogenic effects, involves its demonstrated ability as a competitive antagonist of the depressant effects of adenosine analogs in the central nervous system. Adenosine and its derivatives have been shown to inhibit neuronal electrical activity, the release of neurotransmitters, and to interfere with synaptic transmission.19-24 27... 

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