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Title: Hierarchical architecture of dopaminergic circuits enables second-order conditioning in Drosophila
Dopaminergic neurons with distinct projection patterns and physiological properties compose memory subsystems in a brain. However, it is poorly understood whether or how they interact during complex learning. Here, we identify a feedforward circuit formed between dopamine subsystems and show that it is essential for second-order conditioning, an ethologically important form of higher-order associative learning. The Drosophila mushroom body comprises a series of dopaminergic compartments, each of which exhibits distinct memory dynamics. We find that a slow and stable memory compartment can serve as an effective ‘teacher’ by instructing other faster and transient memory compartments via a single key interneuron, which we identify by connectome analysis and neurotransmitter prediction. This excitatory interneuron acquires enhanced response to reward-predicting odor after first-order conditioning and, upon activation, evokes dopamine release in the ‘student’ compartments. These hierarchical connections between dopamine subsystems explain distinct properties of first- and second-order memory long known by behavioral psychologists.  more » « less
Award ID(s):
2034783
PAR ID:
10398027
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Date Published:
Journal Name:
eLife
Volume:
12
ISSN:
2050-084X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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