Emotional, motivational, or species-specific behaviour can be elicited by intracranial electrical stimulation (ICS) in unanesthetized and unrestrained animals with chronically implanted electrodes. The purpose of this investigation was to describe and quantify, using an escape and avoidance task, a behaviour called flight, using rats as the experimental animal. An enclosed test box was used that had a hole in one wall covered by a moveable clear plastic plate. With the interior light on and exterior lights off, the hole represented the only opening in the box. Flight was then operationally defined as plate-pushing in response to ICS (escape response). It was found that only 25% of rats which showed manifestations of flight on pre-test screening would perform the escape response. After establishing reliable escape, the rats were given the opportunity to avoid ICS, at the threshold voltage for escape, by responding to a signal (bell, light or click) predicting the occurrence of ICS. In over 200 trials there were at most only 10% avoidances and no tendency for faster responding. A current explanation for this, proposed by W. W. Roberts, was tested by allowing these rats to press a bar for brief ICS at the voltage used in avoidance. Only 40% of the subjects would self-stimulate. These, and other results from the literature suggest that rewarding onset of ICS, as in the Roberts hypothesis, is insufficient to explain the lack of avoidance. The electrode sites producing escape were found to be in the central gray of the midbrain, and in both the medial and lateral divisions of the middle to posterior hypothalamus near the fornix. The sites producing similar behavioural manifestations but not escape were found to be in the same regions of the hypothalamus and midbrain. / Medicine, Faculty of / Graduate

The "hyperphagic syndrome" consists of a number of behavioral changes which normally occur along with the increased weight gain following VMH lesions in the rat. The present study explored the possibility of separating these behavioral changes from the increased weight gain. The behavioral dimensions sampled were activity, tendency to work for food and reactivity to diet adulteration. Three different methods were employed to produce the increased weight gain: electrolytic VMH lesions, cuts lateral to the VMH, and cuts anterior to the VMH. The results confirmed the decreased activity, decreased tendency to work for food, and increased reactivity to taste manipulation previously reported for VMH-lesioned animals. Cuts lateral to the VMH were indistinguishable from lesions on each of these measures. Cuts anterior to the VMH resulted in no change in normal activity level or in the tendency to work for food but did result in increased reactivity to taste manipulation. The results are consistent with the notion of a medial-lateral system controlling some facit of energy balance and of an anterior system underlying a sex dependent part of the weight gain in female rats. / Arts, Faculty of / Psychology, Department of / Graduate