Research was undertaken in an attempt to clarify the relationship between stimulus-bound eating and self-deprivation produced by electrical stimulation of the lateral hypothalamus. It was hypothesized that if these two phenomena are mediated through a common population of feeding-related neurons, a significant correlation should be observed between these two behaviors. No significant relationship was discovered among the rats tested for both stimulus-bound eating and self-deprivation. Although this finding by itself does not rule out some role for feeding-related neural elements in stimulus-bound eating and self-deprivation, the present results provide no support for this view and suggest alternative explanations should be sought.

In order. to assess the effect of changes in brain-stimulation reward (BSR) on food intake, train duration of BSR was manipulated during food/BSR competition periods. Train duration, rather than intensity, was used in order to hold the area of stimulation about the electrode tip constant. Train duration had a significant effect on food intake, with longer durations decreasing intake. Increases in food deprivation increased feeding during food/BSR competition, and the tendency for subjects to self-deprive was reduced over the 4 weeks of successive competition testing. Further analyses of the data revealed that stimulation on-time (defined as the product of leverpresses and train duration) was a better predictor of food intake than was leverpressing rate. The results are interpreted as supporting the hypothesis that choices for food or BSR during competition reflect the relative reward value of the alternatives.The potency of brain-stimulation reward (BSR) has been dramatically demonstrated by its ability to compete with behavior that has biologically relevant consequences (Carlisle & Snyder, 1970;Eckert & Lewis, 1967;Morgan & Mogenson, 1966;Rossi & Stutz, 1978;Routtenberg & Lindy, 1965;Spies, 1965;Stutz, Rossi, & Bowring, 1971). It has been argued that self-stimulation competes with other reinforcers by virtue of its rewarding properties (Rossi & Stutz, 1978;Stutz, Rossi, & Bowring, 1971) as opposed to its ability to reduce the competitive drive (Spies, 1965). This conclusion is based on the findings that animals who self-starve in order to obtain BSR also self-dehydrate, and that experimenter-administered brain stimulation does not significantly reduce food intake in food-deprived animals who have previously .self-starved. Further support for this position is found in research showing that the ability of BSR to compete with sweetened water is a function of the liquid's palatability (Phillips, Morgen, & Mogenson, 1971) and that food deprivation increases responses for food during BSR/food competition periods (Miliaressis & Cardo, 1973;Morgan & Mogenson, 1966 , 1972;Keesey, 1964;Ridgway, Pliskoff, & Mcintire, 1965). Increases in BSR induced by longer train durations are apparently mediated through temporal summation within a discrete population of neurons, while changes in the intensity of the stimulation modify BSR via spatial summation (Gallistel, 1973). Therefore, in order to assess the effect of changing BSR on self-deprivation with the area of stimulation held constant, train duration rather than intensity was manipulated. It was assumed that longer durations more effectively stimulate a finite population of neurons around the electrode tip whereas manipulation of intensity widens the field of stimulation. If the amount of food eaten during simultaneous access to BSR and food is an index of the comparative reward values of the reinforcers, food intake should decrease with increasing train durations. METHOD SubjectsTwenty naive male Sprague-Dawley rats (Blue Spruce Farm, Altamont, New York), weighing 350-425...

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