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. 2023 Jan 25;12:e80594. doi: 10.7554/eLife.80594

Figure 2. The organization and development of the larval and adult mushroom bodies (MBs).

Figure 2.

(A) The larval MB has a core of γ Kenyon neurons whose dendrites project to the calyx (CA) neuropil and whose axons extend through the peduncle and bifurcate into a vertical and medial lobe. Projections from three clusters of aminergic neurons, the PAL, PPL1, and PAM clusters divide the axon array into 10 computational compartments: IP and LP: intermediate and lower peduncle; LA: lateral appendix; UVL, IVL, LVL: upper, intermediate, and lower vertical lobe; SHA: shaft; UT, IT, LT: upper, intermediate, and lower toe. PPL1 input largely indicates punishment, PAM input indicates reward, and PAL is unknown. The diagrams below highlight in gray (left) the compartments that lose contact with γ neuron axons during pruning and (right) the compartments that are not incorporated into the adult MB. (B) The adult MB has 16 compartments. It contains regrown γ neurons (gray) that lack the larval-specific vertical branch along with late developing α′β′ (green) and αβ (orange) Kenyon cells. These together form the medial (β′,β) and vertical (α′, α) lobe systems of the adult. Compartment designations are numbered and based on the Kenyon cell axons that they contain. (C) Projection of a multicolor flip-out (MCFO) image from a larval brain showing two MB input neurons that project bilaterally to the upper (UVL) and intermediate (IVL) compartments of the vertical lobes. Blue: neuroglian staining. (D) Schematic of the microcircuitry characteristic of larval and adult compartments. (E) Developmental timeline of the production of the three major classes of Kenyon cells that make up the mature MB.

Figure 2—source data 1. Examples of the adult anatomies of larval neurons MBIN-b1 and -b2 obtained by flip-switch-mediated immortalization of expression of line SS21716 late in larval life.
Figure 2—source data 2. Examples of the adult anatomies of larval neurons DAN-c1 and DAN-d1 obtained by flip-switch-mediated immortalization of expression of lines MB586B and MB328B, respectively, late in larval life.
Figure 2—source data 3. Examples of the adult anatomy of larval neuron OAN-e1 obtained by flip-switch-mediated immortalization of expression of lines SS21716 and SS01958 late in larval life.
Figure 2—source data 4. Examples of the adult anatomies of larval neurons MBIN-l1 and DAN-f1 obtained by flip-switch-mediated immortalization of expression of stable spilt lines late in larval life.
The anatomy of the adult form of MBIN-l1 was revealed using lines SS04484 and SS01624; that of DAN-f1 using lines MB065B and MB145B.
Figure 2—source data 5. Examples of the adult anatomies of larval neurons DAN-g1 and OAN-g1 obtained by flip-switch-mediated immortalization of expression of stable spilt lines late in larval life.
The anatomy of the adult form of DAN-g1 was revealed using lines SS017164 and SS01755; that of OAN-g1 using lines SS20844 and SS4268.
Figure 2—source data 6. Table showing the success rate for maintaining expression of the various larval neurons through metamorphosis.