Extended Data Fig. 9. Artificial activation of β′2, γ4, and γ5 DANs simultaneously conveys multiple reward types and satiety-like signals.
a, In healthy flies, β′2, γ4, and γ5 PAM DANs are activated by specific reward-type upstream neurons (USNs, with excitatory arrow inputs) and modulated by modulatory USNs (with modulatory circle inputs). Some modulatory USNs may also inhibit PPL1 DANs that convey aversive punishment to the γ1 and γ2 compartments29,30. The PAM DANs are coloured according to the rewards they may represent according to prior studies21,23–28,45 in addition to rewards that have not yet been identified. When a healthy fly encounters a reward in a presence of an odour, the reward activates only specific reward-type USNs, whose activation of PAM DANs is concurrent with modulatory input from USNs conveying information about the corresponding physiologically relevant internal state. The PAM DANs therefore convey specific reward teaching signals (and associated satiety-like signals) in a state-appropriate manner to mushroom body Kenyon cells that are coincidentally activated by the odour, leading to normal reward-driven depression of avoidance output pathways. Since approach pathways from the mushroom body are unaffected by reward signalling, flies subsequently demonstrate a net approach to the reward-associated odour, enabling flexible state-dependent reward seeking and motivation. b, In flies whose β′2, γ4, and γ5 PAM DANs express CsChr and are activated directly by red light, information about specific reward types and physiologically relevant internal states is disregarded. The PAM DANs convey a non-specific reward teaching signal consisting of the combined value of multiple rewards (and multiple satiety-like signals) to Kenyon cells, leading to supranormal depression of avoidance output pathways. Flies subsequently demonstrate supranormal approach to the red-light-associated odour, resulting in state-independent reward seeking and demotivation to other natural rewards. PPL1 DANs that convey aversive punishment to the γ1 compartment also consequently undergo indirect inhibition, which manifests when flies display punishment-resistant reward seeking.