There is no significant difference in learning index between wild-type and amn^unspecified mutants at three hours after training, although there is a significant difference at eight hours, when the learning index of the mutants drops to zero.

The time taken to immobilise 50% of flies in an ethanol sensitivity assay is shorter than that of wild-type flies.

Mutant flies have a limited ability to focus attention on specific visual figures in a visual stimulus assay.

The population of neurons in the central nervous system that exhibit K⁺ currents differs from wild type; the number of type II neurons is less than a third of those of wild type, type II neurons are twofold more abundant than in wild type and type I neurons are 1.5-fold more abundant than in wild type. A larger proportion of K⁺ currents are sensitive to cAMP compared to wild type. The proportion of neurons with long time constants is reduced.

The ability to learn is normal in amn^unspecified flies, but the learning level is reduced. The 30 and 60 minute memory are blocked in these flies, but other aspects of memory are not significantly affected.

amn^unspecified flies have calyxes that are increased in volume by 5.4% compared to control flies. In wild-type animals, increasing the density at which larvae are reared results in an increase in the volume of the calyx in the adult brain. This plasticity is abolished in amn^unspecified mutants.

Irregularity of heart rhythm is pronounced compared to wild-type in homozygous amn^unspecified animals tested at the transition between larva and pupa at 20, 25, 30, 35 or 37^oC. The heart rate is significantly lower than wild-type in homozygous amn^unspecified animals tested at the transition between larva and pupa at 25, 30, 35 or 37^oC.

Homozygous larvae show no initial learning in an odour avoidance test. Homozygous adults derived from larvae conditioned using the odour avoidance test show no memory retention, in contrast to wild-type flies.

Flies show a low habituation index to sucrose stimuli applied to the tarsus, although as they also show a lower initial responsiveness, habituation may be similar to wild-type flies.