Dept. of Biology and Center for Neural Science, 1009 Main Bldg., New York University, New York, NY 10003
The necessity of performing a task in order to learn it defines many forms of learning, such as the associative conditioning of courtship in Drosophila. In the courtship suppression paradigm, initial performance corresponds to the modification of the male's behavior during his exposure to a mated female, during which time he normally decreases his courtship. Subsequent exposure of the male to a virgin female tests the success of the earlier stimulus in producing an enduring modification of his behavior. Males expressing a transgenic inhibitor of protein kinase C and then subjected to the courtship suppression paradigm exhibit a selective deficit in immediate performance with no effect on their final retention of conditioning. When protein kinase C is moderately inhibited in these males, they are normal for locomotion, olfactory response and courtship of virgin females. When placed with mated females, however, they do not exhibit any overt suppression of courtship, continuing at high levels throughout the conditioning period. When subsequently placed with virgin females, they nonetheless exhibit a depressed level of courtship as if they had been successfully conditioned during their previous exposure to the mated females. The dissociation of immediate response from longer lasting modification points to a selective role for the PKC second messenger system in the feedback of conditioning on immediate performance.