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The prediction was made that by increasing the synthesis of striatal acetylcholine, through local injection of its precursor choline, the acquisition of a lever-pressing response in two different autoshaping situations would be accelerated. In the first experiment, choline was injected into the striatum or parietal cortex of rats immediately after dipper training; 24 h later and during 5 consecutive days the animals were submitted to an autoshaping procedure of the operant kind. In the second experiment, choline was administered to the same regions shortly after each of three classical-operant autoshaping sessions; during the next two sessions, autoshaping contingencies of the operant kind were in effect. In both experiments choline injection into the striatum induced a marked facilitation of acquisition of the conditioned responses, although cortical injection of choline produced a milder improvement only in the first experiment. These results indicate that striatal cholinergic activity is, indeed, involved in the early phases of positively reinforced learning.

Rats were trained on a passive avoidance task, and a retention test was carried out 24 h later. Scopolamine was injected into the anterior striatum at one of various intervals following training: at 2 min it produced amnesia; an intermediate degree of impairment was found when given 8 min after training. With a delay of 15 min, this drug did not produce an interference with memory. These observations suggest that striatal cholinergic activity is involved in memory consolidation.