An important difference between these studies is the time at which memory was tested. Shock-memory was tested 3, 5 or 30 min after training37,38, sucrose memory was tested 3 hrs after training21, and ethanol memory was tested 24 hrs after training. It is possible that output of distinct subsets of mushroom body neurons is required for different stages of memory. For example, recent work suggests that animals that receive multiple spaced odor-shock pairings form a memory trace in the αβ neurons between 9 and 24 hrs after training, and in the γ neurons between 18 and 48 hrs after training40.
