Theoretical models of chemoreceptor discharge patterns

Abstract

The firing patterns of single afferent fibers from the carotid body chemoreceptors exhibit an apparently random behavior in that the inter-spike interval histogram has an exponential form and a plot of standard deviation versus mean interval results in an identity relationship over much of the physiological range. When only these fundamental tests are applied, there are a large number of models which can account for this kind of activity. There are six such models which are being investigated in our laboratory. Among these are models which assume the involvement of a transmitter substance and those which provide for local potential fluctuations resulting from the opening and closing of ionic channels. Also included are models which utilize either the notion of a transmitter reservoir or the concept of several regularly firing collateral receptor axons summing centrally to produce an apparently random pattern. Each of the models produce data similar to that which has been experimentally developed when only interspike interval histograms, means and standard deviations are used. However, they are distinguishable when more sophisticated measures such as higher moments, autocorrelation functions, and serial correlation measures are applied.