@article {68008,
	title = {Hierarchical architecture of dopaminergic circuits enables second-order conditioning in Drosophila},
	journal = {eLife},
	year = {2023},
	month = {2023 Jan 24},
	abstract = {<p>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\&nbsp;<em>Drosophila</em>\&nbsp;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 {\textquotedblleft}teacher{\textquotedblright} 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 {\textquotedblleft}student{\textquotedblright} compartments. These hierarchical connections between dopamine subsystems explain distinct properties of first- and second-order memory long known by behavioral psychologists.</p>
},
	doi = {10.7554/eLife.79042},
	url = {https://doi.org/10.7554/eLife.79042},
	author = {Daichi Yamada and Daniel Bushey and Li Feng and Karen Hibbard and Megan Sammons and Jan Funke and Ashok Litwin-Kumar and Toshihide Hige and Yoshinori Aso}
}
