Visual Pattern Memory Requires "Foraging" Function in the Central Complex of "Drosophila"

The role of the "foraging" ("for)" gene, which encodes a cyclic guanosine-3',5'-monophosphate (cGMP)-dependent protein kinase (PKG), in food-search behavior in "Drosophila" has been intensively studied. However, its functions in other complex behaviors have not been well-characterized. Here, we show experimentally in "Drosophila" that the "for" gene is required in the operant visual learning paradigm. Visual pattern memory was normal in a natural variant rover ("for[superscript R]") but was impaired in another natural variant sitter ("for[superscript S]"), which has a lower PKG level. Memory defects in "for[superscript S]" flies could be rescued by either constitutive or adult-limited expression of "for" in the fan-shaped body. Interestingly, we showed that such rescue also occurred when "for" was expressed in the ellipsoid body. Additionally, expression of "for" in the fifth layer of the fan-shaped body restored sufficient memory for the pattern parameter "elevation" but not for "contour orientation," whereas expression of "for" in the ellipsoid body restored sufficient memory for both parameters. Our study defines a "Drosophila" model for further understanding the role of cGMP-PKG signaling in associative learning/memory and the neural circuit underlying this "for"-dependent visual pattern memory.