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. Author manuscript; available in PMC: 2020 Sep 23.
Published in final edited form as: Nat Neurosci. 2020 Mar 23;23(4):544–555. doi: 10.1038/s41593-020-0607-9

Extended Data Fig. 5. (related to Fig. 3a) Modulatory neurons receive convergent one-step feedback from multiple MBONs from functionally distinct compartments.

Extended Data Fig. 5

Connectivity of each of the 40 feedback neuron (FBN) pairs that provide one-step feedback from MBONs to DANs. Each diagram represents the connectivity of a single left-right pair of homologous FBNs. Each box indicates a separate compartment. Purple, compartment(s) of the presynaptic MBON(s). Green, compartment(s) of the postsynaptic modulatory neuron(s). FBNs are ordered according to the modulatory neuron they innervate, starting with peduncle modulatory neurons and ending with the medial lobe ones. Classical neurotransmitter profiles of the MBONs and FBNs are indicated by the arrow (cholinergic, excitatory connection), vertical line (GABAergic, inhibitory connection) or square (glutamatergic, probably also inhibitory connection) for the neurons for which they are known from immunostaining (For images, see Extended Data Fig. 9 for FBNs and ref.12 for MBONs), or by a circle when they are unknown. 7 FBNs provide exclusively within-compartment feedback. 13 FBNs provide exclusively cross-compartment feedback (named FANs, for feed-across). 8 FBNs synapse onto multiple modulatory neurons from multiple compartments. The largest class of FBNs (17) receives input from multiple MBONs, with the majority (at least 13) receiving input of potentially opposite sign from MBONs from functionally distinct compartments. More than a quarter of FBNs (at least 12) receive direct GABAergic(inhibitory) or glutamatergic (also potentially inhibitory) input from MBONs from one compartment and direct cholinergic(excitatory) input from MBONs from a functionally distinct compartments enabling them to compare the odor drive to these MBONs. Many DANs (DAN-f1, d1, i1, j1, and k1) receive potentially inhibitory (excitatory FBN downstream of an inhibitory MBON) one-step feedback from MBONs from one compartment and potentially disinhibitory (inhibitory FBN downstream of an inhibitory MBON) or excitatory (excitatory FBN downstream of an excitatory MBON) one-step feedback from MBONs from a functionally distinct compartment. A common pattern for the lobe DANs implicated in memory formation may be a likely inhibitory connection from an MBON from their own compartment and a likely disinhibitory connection from an MBON from a compartment of opposite valence (observed for both DAN-g1 and i1), that could enable these DANs to compare the odor drive to MBONs from compartments of opposite valence.