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

Figure 19. Direct connections from MBONs to the central complex (CX).

In this diagram, the central column shows those MBONs that make direct connections of 10 or more synapses onto the dendrites of CX neurons. Such direct connections predominantly occur on fan-shaped body (FB) neurons. Three cell types of nodulus (NO) cell types are also direct targets (see Figure 19—figure supplement 1A); some FB cell types in layers 1, 2, 3, and 4 that are downstream of MBONs also have arbors in the NO. No direct targets were identified in other CX neuropils such as the ellipsoid body (EB) or protocerebral bridge (PB). The number in the circle indicates the MBON cell type; that is, 01 stands for MBON01. The size of the circle indicates what percent of that MBON’s total output (based on synapse number) goes directly to FB neurons. The color of solid circles represents confirmed neurotransmitter types while the color of the outline of hollow circles represents predicted neurotransmitter types. Numbers have been pooled for cases where there are multiple MBONs of the same cell type. The outer columns show FB cell types, arranged by FB layer(s). The name of the cell type and, in parentheses, the number of cells of that type are indicated for those with multiple cells. The percentage of that cell type’s input that comes from MBONs is given and is reflected by the size of the circle representing the cell type. All FB neuron types receive less than 5% of their total input from MBONs except for one layer 4 FB neuron type, CREFB4 (FB4R), which receives nearly 20% of its inputs from two MBONs, MBON09, and MBON21 (see Figure 19—figure supplement 1B,C). Direct MBON connections to the FB are concentrated in FB layers 4 and 5. Links to each of these FB and NO cell types in neuPrint, listed from FB layer 1 to FB layer 9 and then for the nodulus, are as follows: LALNOmFB1 (FB1C), CRENO2,3FB1-4 (FB1H), NOaLALFB2 (FB2A), SMPCREFB2_1 (FB2C), SMPCREFB2_2 (FB2L), CRESMPFB4_1 (FB4A), CRENO2FB4_1 (FB4C), CRESMPFB4_2 (FB4D), CRELALFB4_2 (FB4F_b), CRELALFB4_3 (FB4G), CRELALFB4_4 (FB4H), LALCREFB4 (FB4I), CRELALFB4_5 (FB4J), LALSIPFB4 (FB4L), CRENO2FB4_2 (FB4M), SMPCREFB4 (FB4N), CRESMPFB4d (FB4O), CRESMPFB4_4 (FB4P_a and FB4P_b), CREFB4 (FB4R), CRESIPFB4,5 (FB4X), EBCREFB4,5 (FB4Y), LALCREFB5 (FB5A), SIPCREFB5d (FB5AB), SMPCREFB5_1 (FB5C), CRESMPFB5_1 (FB5D), CRESMPFB5_2 (FB5E), CRESMPFB5_3 (FB5H), SMPCREFB5_3 (FB5I), SMPFB5 (FB5J), CREFB5 (FB5K), CRESMPFB5_4 (FB5L), CRESMPFB5_5 (FB5M), CRELALFB5 (FB5V), SMPCREFB5_8 (FB5X), SMPSIPFB6_1 (FB6A), SMPCREFB6_1 (FB6P), SIPSMPFB6_5 (FB6Q), SMPSIPFB6_7 (FB6R), SIPSMPFB6_7 (FB6T), SMPCREFB6_3 (FB6V), SIPSLPFB8 (FB8F_a), LCNp (LCNOp ), LCNpm (LCNOpm), and LNO1 (LNO2).

Figure 19.

Figure 19—figure supplement 1. The morphology and connectivity of nodulus and CREFB4 neurons.

Figure 19—figure supplement 1.

(A) Morphologies of the LCNp (LCNOp), LCNpm (LCNOpm), and LNO1 (LNO2) nodulus neurons that are downstream of MBONs. The FB, NO, and LAL are shown in gray. Presynaptic sites are shown as yellow dots and postsynaptic sites as gray dots. (A′) Higher magnification view, showing the locations of MBON inputs onto these neurons. (B) CREFB4 (FB4R) neurons are shown with each of the four neurons of this type displayed in a different color. The locations of the synapses CREFB4 (FB4R) cells receive from MBON09 (γ3β′1) and MBON21 are shown, color-coded. (B′-B′′) Alternative views of image shown in (B). (C) Diagram of synaptic connectivity. The numbers in the circles that represent the cells indicate, for CREFB4 (FB4R) cells, the percentage of their input that comes from these two MBONs and, for the MBONs, the percent of their output that goes to CREFB4 (FB4R). The numbers in the arrows are the number of input synapses. The neurotransmitters of the MBONs are indicated.