Fig. 3: The γ lobe of the mushroom body mediates social motivation.

a A diagram to show different brain regions in the adult fly (top) and the inactivation scheme by the GAL4/UAS system (bottom). Different Gal4s drove the expression of TNT in specific neurons in selected brain regions, including the mushroom body (b), ellipsoid body (c), fan-shaped body (d), suboesophageal ganglia (e), protocerebral bridge (f), and AMMC region (g). The social approach level was dramatically altered by expressing TNT in neurons labelled in ok107, MB247, 201y, D52H, and NP1131 lines (a), but not other neurons (a–g). h The social approach levels were affected when silencing populations containing KC_γ neurons in MB010B (α/β + α׳/β׳+γ), MB607B (γ_d), MB419B (γ_d), MB009B (γ_d+main), and MB131B (γ_d+main), but were normal when silencing the KC_α/β and KC_α׳/β׳ neurons (α/β: MB008B, MB477B, MB185B, MB594B, and MB371B; α׳/β׳: MB005B and MB463B). Different KCs occupy distinct layers in the lobes as indicated (a: anerior; d: dorsal; p:posterior; m: medial; c: core; s: surface). Blue, pink, and green circles represents expression in γ, α׳/β׳, and α/β lobe, respectively. i A scheme for inactivating neural activity in a selected time window by elevating the temperature to allow the expression of TNT. Flies containing UAS-TNT-E, tub-Gal80^ts, and various Gal4s were kept at 18 °C for 3 days after eclosion. Subsequently, flies were kept at 29 °C for 2 days. The social approach tests were conducted after restoration at 25 °C for 2 h. j The results of selective inactivation via controlling temperature. The social approach levels were decreased in ok107, MB247, 201y, and NP1131. Results are presented as a box and whisker plot; the whiskers indicate the minimum and maximum, the box includes the 25th–75th percentile, and the line in the box indicates the median of the data set. Statistical analysis: unpaired t-test. ns: P > 0.05, *P < 0.05, **P < 0.01, ***P < 0.001.