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Date of Award

12-1996

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

Supervisor

H.P. Weingarten

Abstract

Conceptual and empirical analyses of the controls of feeding have emphasized the role of peripheral factors in the control of ingestive behaviour. Currently, it is understood that feeding is under the control of multiple peripheral factors. It follows that if eating is the result of multiple signals, it is necessary to design experiments that examine the ways in which these signals interact and combine to influence eating. The experiments in this thesis accommodate the acknowledged multifactorial control of eating by examining the interaction of two classes of peripheral signals--oral (from the mouth) and gastric (from the stomach). The aim of the experiments is to determine how these two classes of signals interact to influence activity in the CNS (central nervous system) Fos immunohistochemistry was used as the marker of neural activity because of its practicality in determining brain areas activated by experimental treatments and since the technique provides a means to quantify the number of neurons activated. The first experiment was designed to confirm that Fos immunoreactivity could be used as a marker of neural activity induced under "physiological" conditions of feeding. The second experiment used sham feeding and real feeding to compare the patterns of neural activity stimulated by oral stimulation in isolation (sham feeding) or oral and gastric stimulation in combination (real feeding). The third experiment specifically compared FLI patterns induced by oral and gastric stimulation, each presented alone, or in combination under conditions of strict experimenter control. The fourth experiment continued this line of inquiry by addressing whether the order of the two stimulations, one appropriate (oral followed by gastric) and the other reversed (gastric followed by oral), influenced the Fos-like immunoreactivity (FLI) patterns seen in previous experiments. The final experiment examined whether the effect of order also had functional consequences with regard to the control of eating.

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