Enhanced olfactory memory detection in trap-design Y-mazes allows the study of imperceptible memory traces in Drosophila

Abstract

The neural basis of behavior is identified by systematically manipulating the activity of specific neurons and screening for loss or gain of phenotype. Therefore, robust, high-scoring behavioral assays are necessary for determining the neural circuits of novel behaviors. We report a simple Y-maze design for Drosophila olfactory learning and memory assay. Memory scores in our Y-mazes are considerably better and longer-lasting than scores obtained with commonly used T-mazes. Our results suggest that trapping flies to an odor choice in a Y-maze could improve scores. We postulated that the improved scores could reveal previously undetectable memory traces, enabling the study of underlying neural mechanisms. Indeed, we identified unreported protein synthesis-dependent long-term memories (LTMs), reinforced by ingestion of (1) an aversive compound and (2) a sweet but nonnutritious sugar, both 24 h after training. We also used Y-mazes to probe how using a greater reward may change memory dynamics. Our findings predict that a greater sugar reward may extend existing memory traces or reinforce additional novel ones.

Breaking free from the clock’s tyranny restores memory to brain damaged flies

“…To further examine the role of sleep in restoring STM to brain damaged flies, we fed larvae HU and examined aversive olfactory memory using the recently described Y-maze ( 75 ) (Figure 1H). As above, HU was effective in eliminating most KCs (Figure 1I).…”

Influence of RVFV Infection on Olfactory Perception and Behavior in Drosophila melanogaster

“…However, it is very unlikely that reduced odor choice in our experiments can be explained by the reduced locomotor activity of infected flies alone, because the design of the Y-maze with its small start chamber strongly reduces possible effects of general activity [59], as opposed to, e.g., upwind-T-maze tests that strongly rely on locomotor activity [72]. Thus, in our experiments conducted for 24 h, participation rates in the test were high in both RVFV and control groups.…”

“…This could be explained by the high vapor pressure of ethyl acetate as compared to the other odorants [69][70][71], which prevents its usage in the Y-maze assay. However, we consider the Y-maze superior to air-flow based olfactory choice assays because the uncomfortably small start tube enforces choice and the assay does not depend on locomotion against an air stream [72]. This is particularly important in RVFV infected flies that showed less activity.…”