Phototaxis suppression
To ensure that you only use photopositive / photonegative flies for this experiment , do a preselection by running a regular , single - trial photoxasis experiment without aversive stimulus and collect only the flies in either the bright or the dark tube .
After placing the filter paper in the appropriate tube and with the elevator down , load the selected flies ( around 50 ) into the entrance tube and give them 10 minutes for dark adaption .
Shift the elevator all the way up , tap the flies into the elevator and move it to the middle position ( between the entrance tube and the dark tube ) .
Bring the T - maze back into the vertical position and put the elevator with the flies all the way down .
Now let the flies choose between the bright tube and the dark tube for 30 seconds .
Tap all the flies into the tube which doesn’t contain the aversive stimulus ( The elevator is still down ) .
Take this tube and put all the flies in the entrance tube again ( with a funnel ) .
Let them calm down for 15 seconds .
Repeat the " Bright / dark tube choice " section ( steps 3 through 8 ) .
Switch the tube which contains the aversive stimulus with a tube without any filter paper and repeat the " Bright / dark tube choice " section ( steps 3 through 8 ) .
Put the elevator up and count the flies in the entrance tube , the transparent tube and the opaque tube after anesthetizing them .
