Figure 4.

dAlk levels in the adult MBs during conditioning enhance or constrain LTM performance. Mean PIs (bars) ± SEMs (error bars) are shown. The number of experimental replicates (n) are indicated within the bars. *Significant differences denoted by horizontal line pairs. n.s. means not significant. A, Attenuation of dAlk expression levels with the dAlk^RNAi(11446) transgene restricted specifically to the adult CNS for 48 h before training yielded significant LTM increase (black bars) compared with controls (light and dark gray bars) when the transgene was expressed pan-neuronally (Elav;G80^ts), in all MB neurons (LeoMB;G80^ts) and more specifically in α/β MB neurons (c739;G80^ts). B, Conversely, adult-specific overexpression of the wild-type dAlk^WT transgene using the same indicated G80^ts drivers elicited significant LTM deficits. In contrast, ARM and learning/3 min memory (Massed and STM) were not affected. C, Induction of dAlk^WT expression in adult c739;G80^ts MB neurons for 8 h before conditioning (t_{−8 h}-t₀) resulted in deficient LTM; but in contrast, it left LTM intact if the transgene was induced for 8 h immediately following conditioning (t₀-t_{+8 h}), or 8 h before testing (t_{+16 h}-t_{+24 h}), as indicated in the diagram below.