Dopaminergic neurons dynamically update sensory values during olfactory maneuver.

Dopaminergic neurons (DANs) drive associative learning to update the value of sensory cues, but their contribution to the assessment of sensory values outside the context of association remains largely unexplored. Here, we show in Drosophila that DANs in the mushroom body encode the innate value of odors and constantly update the current value by inducing plasticity during olfactory maneuver. Our connectome-based network model linking all the way from the olfactory neurons to DANs reproduces the characteristics of DAN responses, proposing a concrete circuit mechanism for computation. Downstream of DANs, odors alone induce value- and dopamine-dependent changes in the activity of mushroom body output neurons, which store the current value of odors. Consistent with this neural plasticity, specific sets of DANs bidirectionally modulate flies' steering in a virtual olfactory environment. Thus, the DAN circuit known for discrete, associative learning also continuously updates odor values in a nonassociative manner. [Display omitted] • A population of dopaminergic neurons (DANs) encodes the innate value of odors • A connectome-based simulation proposes circuit mechanisms underlying DAN odor responses • Odors alone induce value- and dopamine-dependent changes in the activity of MBONs • DANs continuously update odor values in a nonassociative manner Kato et al. show that Drosophila dopaminergic neurons encode innate values of odors and continuously update the values in a nonassociative manner as animals explore the environment. Perturbation of dopamine signaling uncovers that odors alone cause value- and dopamine-dependent changes in the neural output of association area and behavior. [ABSTRACT FROM AUTHOR]