Models for scopolamine, atropine and amphetamine effects on an alternate bar pressing paradigm

Abstract

A hypothetical neural network is presented to account for errors made by food-deprived albino-rats in a bar-pressing situation (Carlton, 1964). The rats were required to press alternately on two bars in order to activate a device that releases milk to them. When-ever an animal pressed consecutively on the same bar, no milk was released and the animal was scored as having committed an error. In the first part of the paper, a time-independent neural network, part of which is equivalent to the psychophysical discrimination network of H. D. Landahl (1938), is used to interpret the effects on the animals’ performances of the drugs amphetamine, scopolamine and atropine. Suggestions for further experiments are made on the basis of the initial form to the model. In the second part of the paper, certain parameters of the initial form of the model are assumed to be time-dependent and a further generalization occurs through the introduction of the interresponse time distribution. It is shown that, under specified conditions, the second form of the model reduces to the first. The time-dependent form of the model allows certain features to be discussed that could not be discussed in the time-independent form [e.g. P. Dew’s (1961) notion of a possible mode of action for a variety of the behavioral effects of amphetamine]. Furthermore, experiments of an essentially different type from those discussed in the first part can be proposed to aid in the development of a theory for this kind of behavioral situation.