Dopamine neurons drive competing actions for alcohol preference in Drosophila. Karla R. Kaun, Reza Azanchi, Yoshinori Aso, Gerald M. Rubin, Ulrike Heberlein. Howard Hughes Medical Institute, Janelia Farm Research Campus, 19700 Helix Drive, Ashburn, VA 20147.

   Neural circuits that mediate behavioral choice evaluate and integrate information from the environment with internal demands, then initiate an output response. Even circuits that support simple decisions remain poorly understood. Here we characterize the neural modulation underlying the simple choice to lay eggs on ethanol and show that distinct subsets of dopaminergic neurons compete to either enhance or inhibit egg-laying on ethanol. We propose a model where competing dopaminergic neurons modulate oviposition preference in order to adjust to changes in natural oviposition substrates. Moreover, we show that the circuits that mediate this innate choice overlap with the reward circuits responsible for evaluating the appetitive and aversive effects of intoxicating levels of ethanol. This suggests circuits that evolved to evaluate an oviposition substrate beneficial to the fitness of the flies, may be more generally required to evaluate appetitive and aversive stimuli.