Relationship between visual learning/memory ability and brain cAMP level in Drosophila.

Using the flight simulator system, the operant conditioned visual flight orientation behavior in Drosophila was studied. It was demonstrated that the visual learning performance is associated with age; flies learn more reliably at 3-4 days than at 1-2 days of age; the cAMP level of brain is also increasing with age; the brain cAMP content of nonlearner flies of wild type is much higher than that of normal flies; the cAMP level of brain increased abnormally after being fed with caffeine, and the learning performance decreased. These results imply that a moderate range of cAMP level is necessary for the visual learning and memory process. Abnormally high or low level of cAMP causes defects of learning and memory ability.