Models of heterogeneous dopamine signaling in an insect learning and memory center
Fig 9
Model behavior for a navigation task.
(A) Top: Schematic of navigation task. After conditioning, the simulated organism uses odor concentration input (blue) and information about wind direction w relative to its heading h. Bottom: Diagram of a network that uses these signals to compute forward and angular velocity signals for navigation. Velocity signals are read out from other neurons in the mushroom body output circuitry (gray), rather than output neurons. (B) Position of the simulated organism as a function of time during navigation. Black: Simulation with intact dopamine-gated plasticity during navigation; Red: Simulation with plasticity blocked. Arrowheads indicate direction of movement. In the top left plot, the starting location (gray circle) is indicated. (C) Position error (mean-squared distance from rewarded odor source at the end of navigation) for control networks and the same networks in which dopamine-gated plasticity is blocked during the navigation phase. For each network realization, error rates are computed over 50 test trials and bars represent s.e.m. over 30 network realizations. Significance is computed with a Wilcoxon signed-rank test. (D) Forward (top) and angular (bottom) velocity as a function of time during one example navigation trial. (E) Left: Dopamine neuron activity during CS and US presentation in the conditioning phase of a trial. Right: Dopamine neuron activity during the navigation phase of the trial (same trial as in D).