The antibiotic, puromycin, caused loss of memory of avoidance discrimination learning in mice when injected intracerebrally. Bilateral injections of puromycin involving the hippocampi and adjacent temporal cortices caused loss of short-term memory; consistent loss of longer-term memory required injections involving, in addition, most of the remaining cortices. Spread of the effective memory trace from the temporal-hippocampal areas to wide areas of the cortices appears to require 3 to 6 days, depending upon the individual animal. Recent reversal learning was lost while longer-term initial learning was retained after bilateral injections into the hippocampal-temporal areas.

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An animal's food intake is related to the stimulus properties, or palatability, of its diet and to its body weight. Both normal and hyperphagic rats were fed different diets (powder, pellets, a high-fat diet, and a mineral and fat diet) and gained weight to different asymptotic levels. Food intake was directly related to the palatability of the diet and inversely related to the animal's body weight. These relationships obtained both in normal and in hypothalamic hyperphagic animals. Hyperphagics were more responsive to palatability than were normal animals, but the two groups apparently did not differ in their response to body weight.

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Twenty-five subjects evaluated the sweetness, creaminess and fat content of liquid and solid dairy products containing between 0.1 and 52 g fat/100 g and sweetened with 0-20% sucrose weight/weight. Liquid stimuli included skim milk, whole milk, half and half, and heavy cream, while the solids included cottage cheese and cream cheese, blended and spread "jelly-roll" fashion on slices of white bread. The subjects' ratings of stimulus sweetness, creaminess, and fat content differed sharply between liquids and solids, and the assessment of fat content of solid foods appeared to be impaired. In contrast, acceptability ratings for both sets of stimuli were not substantially different: the subjects optimally preferred equivalent levels of sugar in both liquids and solids, but selected higher fat levels in solid than in liquid foods. Sensory preferences for fat in liquid stimuli may not always be indicative of preferences for fat in solid foods.

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