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

• Published in: Learning & memory (Cold Spring Harbor, N.Y.) Vol. 29; no. 10; pp. 355 - 366
• Main Authors: Mohandasan, Radhika, Thakare, Manikrao, Sunke, Suhas, Iqbal, Fathima Mukthar, Sridharan, Madhav, Das, Gaurav
• Format: Journal Article
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 01.10.2022
• Subjects: Drosophila; Insects; Neural networks; Olfactory discrimination learning; Olfactory pathways; Phenotypes; Protein biosynthesis; Reinforcement; Sweet taste
• ISSN: 1549-5485; 1072-0502; 1549-5485
• DOI: 10.1101/lm.053545.121

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.