FoxP influences the speed and accuracy of a perceptual decision in Drosophila

Decisions take time if information gradually accumulates to a response threshold, but the neural mechanisms of integration and thresholding are unknown. We characterized a decision process in Drosophila that bears the behavioral signature of evidence accumulation. As stimulus contrast in trained odor discriminations decreased, reaction times increased and perceptual accuracy declined, in quantitative agreement with a drift-diffusion model. FoxP mutants took longer than wild-type flies to form decisions of similar or reduced accuracy, especially in difficult, low-contrast tasks. RNA interference with FoxP expression in αβ core Kenyon cells, or the overexpression of a potassium conductance in these neurons, recapitulated the FoxP mutant phenotype. A mushroom body subdomain whose development or function require the transcription factor FoxP thus supports the progression of a decision toward commitment. Fruit flies engage a subset of mushroom body neurons to gather information before committing to a choice Decisions, decisions, decisions… Flies, like humans, deliberate before making perceptual judgments: They ponder difficult decisions longer than they do easy ones. DasGupta et al. measured reaction times in flies choosing between different smells. Mutations in a particular gene, they found, could cause indecision. Mutations in the same gene are implicated in intellectual disability, learning deficits, and language impairment. Science, this issue p. 901.