The neuronal architecture of the mushroom body provides a logic for associative learning

“…We defined six PPL1 DAN cell types (PPL101-PPL106; see Figure 1—video 2 for PPL106) and 15 PAM DAN cell types (PAM01-PAM15). These cell type classifications are consistent with previous studies ( Aso et al, 2014a ), except for the addition of one new type, PAM15 (γ5β′2a). There is only a single cell per PPL1-DAN cell type in a hemisphere, and axons of each cell broadly arborize in the compartment(s) they innervate.…”

“…For the other 21 MBON types, we found only minor differences with previous studies ( Aso et al, 2014a ; Takemura et al, 2017 ). For example, MBON15 (α′1) and MBON17 (α′3m), which each were described as having two cells in Aso et al, 2014a ; Takemura et al, 2017 , had additional cells in the hemibrain that were similar in morphology, but had some connectivity differences, that we refer to as MBON15-like and MBON17-like. However, since our observations are based on a single individual, we did not split them into separate cell types.…”

“…Using high-resolution imaging (Figures 1A″–1G″ & Files S8 – S14), we were able to count the total number of MB KCs of each subtype that is labeled by a given spilt-GAL4 combination (Table 1). The numbers of labeled cells for each MB KC subtype are in general agreement with a previous report (Aso et al 2014a) and it appears that most if not all of the neurons of each subtype are labeled with these Split-GAL4 combinations. In fact the total number of KCs labeled by five non-overlapping split-GAL4 lines – MB131B, MB370B, MB371B, MB185B and MB594B – is very close to the estimated total number of KCs (1,855 vs. 2,000; Aso et al 2014a), making it unlikely that any major KC subtype is missed.…”

“…The numbers of labeled cells for each MB KC subtype are in general agreement with a previous report (Aso et al 2014a) and it appears that most if not all of the neurons of each subtype are labeled with these Split-GAL4 combinations. In fact the total number of KCs labeled by five non-overlapping split-GAL4 lines – MB131B, MB370B, MB371B, MB185B and MB594B – is very close to the estimated total number of KCs (1,855 vs. 2,000; Aso et al 2014a), making it unlikely that any major KC subtype is missed. Together, these results confirm the previously reported specificity and comprehensiveness of these split-GAL4 lines to label each of the MB KC neuronal subtypes.…”

“…5F) (Mao & Davis, 2009). These results indicate that a distinct PAM to α’/β’ mushroom body circuit regulates hedonic feeding, which is consistent with known descriptions of anatomical and functional segregation of mushroom body lobes (Aso et al, 2014; Landayan et al, 2018).…”