Figure 1.

Schematic of the protocol used for generating aversive olfactory memories in Drosophila larvae. Training and memory tests are carried out in square shape Petri dishes that in opposite sides have containers where odorants are located (represented in yellow) (a) Training: fifteen or more larvae are exposed for 3 min to only one odorant in a dish half-covered with agar supplemented with 2 M NaCl (Odor A + salt). Then animals are exposed to a second odorant in a different Petri plate half-covered with regular agar. This is one training cycle. This procedure is repeated two more times. Afterwards, memory test is carried out. (b) Memory test: to evaluate aversive olfactory memory, animals are placed in the centerline of a square plate, so they are equally exposed to the two odorants, each one in opposite containers. After three minutes, the number of larvae at both sides of the center area is counted.