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. 2020 Dec 14;9:e62576. doi: 10.7554/eLife.62576

Figure 35. Output neurons from different areas of the SEZ tile the SMP where they synapse onto select DAN subtypes.

(A) Axons from multiple SEZON cell types in clusters 22, 23, 24, 25, 26, 27, and 28 (see Figure 31) that provide strong inputs to DAN subtypes are shown together. (A′) The same SEZON axons shown with synapses connecting to PAM DANs (blue, from five clusters) and to PPL1 DANs (orange, from two clusters); synapse numbers are given in parentheses. (B) The five neurons of SEZON cluster 28 (light blue; these neurons correspond to the SEZON01 cluster 5.4.1 of Otto et al., 2020) branch in the SMP and synapse onto the PPL101 (orange), PAM01-lc (black), PAM01-fb (dark yellow), PAM02-pd (green), and PAM15-uc (yellow) subtypes; synapse numbers are given in parentheses. (C) The single neuron in SEZON cluster 27 (green) branches in the SMP and SIP and synapses only onto PPL106; synapse number is given in parentheses. (D) The single neuron in SEZON cluster 23 (gray) branches in the SMP and connects to positive-valence DANs: PAM01-lc (yellow), PAM01-uc (green), PAM01-nc (blue), and PAM08-md (magenta); synapse numbers are given in parentheses. (E) The axons of SEZON neurons can be matched to those in the FAFB EM volume (Zheng et al., 2018) to permit the retrieval of their dendritic field, which resides in tissue that is missing from the hemibrain dataset; skeleton ID numbers from FAFB are shown. FAFB matches to hemibrain SEZONs are shown and colored to match their hemibrain counterparts (colors correspond to those used in panels B-D); the SEZON 551939 was traced in the left hemisphere in FAFB and a mirror image is shown here to facilitate comparison. Their dendritic fields differ, suggesting these SEZON clusters are likely to convey distinct information. Connections contributing less than 0.5% of a neuron’s total dendritic input have been excluded.

Figure 35.

Figure 35—figure supplement 1. Most strongly connected SEZON clusters exclusively synapse onto positive-valence PAM DANs.

Figure 35—figure supplement 1.

(A–C) Further examples of clusters consisting of SEZONs that connect to specific DAN subtypes. In each panel the neuronal morphology is shown on the left with the brain regions where they contact DANs shown in gray , and on the right a higher magnification view of their output synapses onto specific DAN types are shown, color-coded , with synapse numbers given in parentheses. The threshold for connectivity is 0.5% of the DANs total inputs (Figure 31). (A) The neurons of SEZON cluster 22 (481679524) and its contralateral partner (482076140) branch in the SMP and SLP and synapse onto all 3 PAM11 subtypes (compare to Figure 33). (B) The six neurons in SEZON cluster 26 branch in the SMP and connect to positive-valence γ5 DAN subtypes (blue) and weakly to PAM15 (γ5β′2a) and PAM02 (β′2a) subtypes. (C) The single neuron in SEZON cluster 24 branches in the SMP and connects specifically to PAM08-md (γ4; blue) and PAM08-nc subtypes (green), all PAM01 (γ5) subtypes (yellow). (D) The axons of SEZONs in (A and B) can be matched to those in the FAFB EM volume (Zheng et al., 2018). This registration permits the retrieval of their dendritic fields, which reside in tissue that is missing from the hemibrain dataset. FAFB matches to hemibrain SEZONs are shown and are colored to match their hemibrain counterparts in panels (A) and (B). The dendritic fields differ, suggesting these SEZONs convey distinct information. Connections contributing less than 0.5% of a neuron’s total dendritic input have been excluded.