Long-term but not short-term blockade of dopamine release in Drosophila impairs orientation during flight in a visual attention paradigm.

Dopamine is a major neuromodulator in both vertebrates and invertebrates and has profound effects on many physiological processes, including the regulation of attention. Most studies of the functions of dopamine use models with long-term blockade of dopamine release and few effects of transient blockade have yet been reported. The goal of the present study was to determine the role of dopamine in attention-like behavior in Drosophila by taking advantage of the fly's orientation behavior during flight. The examination of several different transgenic flies in a single-target visual attention paradigm showed that flies lost their orientation ability if dopamine release was blocked from the beginning of the development of dopaminergic neurons. This is similar to the attention loss in mammals. However, if the blockade of dopamine release was induced during the experimental procedure, flies performed normally. Statistical analysis of the behavioral assessment showed a significant difference between long-term and transient blockade. Using the RNA interference approach, we generated flies with down-regulated J-domain protein, which is a potential cochaperone in synaptic vesicle release, to make an alternative form of long-term dopamine-blockade mutant. Behavioral assays revealed that flies with permanent J-domain protein down-regulation specifically in dopaminergic neurons have an attention defect similar to that induced by long-term blockade of dopamine release. Furthermore, dopamine depletion beginning at eclosion also caused an attention deficit. Our results indicate that prolonged but not transient blockade of dopamine release impairs visual attention-like behavior in Drosophila.