In Experiment 1, rats previously trained on both brightness and pattern discrimination habits underwent discrete bilateral lesions of either the nucleus posterior, red nucleus, or substantia nigra; retention data indicated that the pattern habit was significantly more impaired than the brightness habit. In Experiment 2, extensive bilateral pretecto-diencephalic damage produced profound disturbances in relearning both visual habits, while extensive lesions of the anterior thalamus or subcollicular area produced only slight disturbances in relearning. In Experiment 3, lesions of either the nucleus posterior, red nucleus, or substantia nigra impaired retention of a kinesthetic discrimination; extensive pretecto-diencephalic damage produced a retention deficit on the kinesthetic habit comparable in severity to that observed on visual habits.

Twelve rats with amygdala damage (CBM) and 20 sham-operated controls were tested in several food-related situations. The CBM rats showed a longer latency to eat than controls in a novel environment due to more pronounced exploration. In the competition for food, CBM rats lost 85% of encounters with controls. Immediately after the contest, when allowed to eat singly, CBM rats displayed a higher persistence of alimentary responses to an emptied cup than did controls, presumably because they experienced more losses in the food competition. Both groups were equally able to overcome obstacles on the way to food, which suggests similar alimentary motivation. The only direct indication of a lowered responsiveness to hunger in CBM rats was 24-hr-fasting-induced hypophagia. The results of this study indicate the involvement of the cortico-basomedial amygdaloid region in the control of relations between alimentary and other motivations. The contribution of eventual changes of food motivation in the postoperative alteration of this balance is discussed.

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