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In order to test the effects of sodium barbitone on the acquisition and retention of an appetitively and an aversively reinforced behavior, mice were trained in a spatial discrimination Y-maze task. Learning was observed in both situations, with acquisition unimpaired by the drug. Sodium barbitone did, however, affect retention of both tasks in all groups treated with the drug before training. Results are discussed in light of the various modes of action of this drug, i.e., as an inhibitor of protein synthesis, as a blocker of catecholamine biosynthesis, with regard to its effects on paradoxical sleep and on gamma-amino-butyric acid (GABA).

In order to investigate whether conditioned circling interferes with recovery from turning induced by unilateral substantia nigra (SN) lesion, rats were trained to turn either ipsi- or contralateral to the lesioned side before and after the lesion was made. Two yoked groups served as controls. The number of turns contralateral to the trained side was significantly lower in relation to the pre-lesion value for the ipsilateral trained group and remained so until the end of the experiment. A partial recovery was observed on the 19th post-lesion day for the contralateral trained group. The results are discussed in terms of additive effects from training and the lesion symptoms.

Experiments were undertaken to investigate the effects of the neuropeptide Substance P (SP) on performance of a conditioned inhibitory avoidance response in rats. A single-trial inhibitory avoidance task was employed. In Experiment 1 SP was injected IP immediately after the training trial in doses of 0.5, 5, 50, 100, 250 or 500 micrograms/kg; control animals were injected with diluent vehicle. The group treated with 50 micrograms SP/kg exhibited better avoidance than the other groups. In Experiment 2 the doses of SP used were 1, 50, 250 micrograms/kg, and the control animals were injected with vehicle or not injected at all. Only the 50 micrograms SP/kg treatment group showed significantly better performance. In Experiment 3 50 micrograms/kg SP or vehicle was injected post-trial immediately or 5 hr after the trial. Only the group in which SP was injected immediately after the training trial showed significantly better performance when tested 24 hr later. This result rules out the possibility that SP exerts its effect by a long lasting proactive action on performance during the testing trial 24 hr later.

Avoidance learning followed by reversal learning was tested in rats after removal of all telencephalic brain structures. In phase I, 24 h after ablation of the telencephalon, rats were given a learning trial in the up-hill avoidance task and tested for retention 2 h later. The animals receiving a tail-shock contingent on the up-hill response showed significant increases in step-up latencies in comparison with control animals that had received noncontingent shock. In phase II, rats of the "reversal learning" group received a tail-shock if they did not perform the up-hill response within 5 s. Control animals received either another up-hill contingent shock or no shock. Two hours later the "reversal" group animals showed a decrement in step-up latencies in comparison with control animals, suggesting that reversal learning of the up-hill avoidance task is possible in rats devoid of the telencephalon.

Behavioral effects of unilateral microinjections into periventricular structures of bicuculline, a classic GABA-A antagonist, and semicarbazide, a glutamic acid decarboxylase blocker, were studied in detelencephalated rats. These drugs produced a behavioral activation together with jumps. However, the characteristics of this behavioral activation differed as the injections were made in dorsal periaqueductal gray matter or medial hypothalamus. These data show close similarities to those observed with intact animals suggesting that GABA-A receptors are involved in the neural control of expression of flight behavior and functions in an intact manner and possibly independent of influences from forebrain structures. At variance with intact animals, these drugs produced contralateral turning behavior when locally injected into MH, pointing to some kind of inhibitory control exerted by telencephalic structures on the expression of circling behavior from diencephalic regions.

Experiments were conducted to determine whether rats having unilateral or bilateral ablation of either the neocortex or telencephalon can learn to escape from a tank of water by climbing a platform. Hemi- or bilaterally decorticated rats were able to learn the swimming escape task, the same being observed for hemidetelencephalated rats. Fully detelencephalated rats, however, did not exhibit this capability. These results show that integrity of one of the cerebral hemispheres is necessary in order to allow swimming escape learning.