The Helico Maze allows testing of early learning and subcategories of long-term memory in mice

• Published in: Behavioural brain research 2021-05, Vol.406, p.113242-113242, Article 113242
• Main Authors: Escoffier, Guy, Migliorati, Martine, Rahrah, Melinda, Roman, Charles S.M., Khrestchatisky, Michel, Roman, François S.
• Format: Article
• Language: English
• Subjects: Animals; Association; Behavior, Animal - physiology; Cognitive science; Declarative-like memory; Hippocampus; Hippocampus - physiology; Learning; Life Sciences; Male; Maze Learning - physiology; Memory; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred DBA; Mouse; Neuropsychological Tests; Olfactory Perception - physiology; Procedural memory; Reference memory; Reward
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2021.113242

•A new apparatus for testing learning and memory in mice has been developed.•Olfactory cues are associated with positive or negative rewards.•Procedural long-term memory can be easily evaluated.•Reference long-term memory can be easily evaluated.•Early deficits in reference memory can be observed using this new apparatus. Different memory systems operate in parallel to support behaviour. To evaluate procedural and reference subcategories of long-term memory as early as possible in the mouse, the Helico Maze (HM) was developed. BALB/c AnNCrl (BALB), C57BL/6JRj (C57) and DBA/2 JRj (DBA) mice were trained on this new maze. The three strains learned how to use the HM (procedural memory), and they then learned and remembered four odour-reward associations (reference memory). The three strains differed in the number of correct responses. BALB mice showed better performance than C57 and DBA mice. The results of the first block of each session revealed that only the BALB and C57 mice remembered the odour-reward associations. DBA mice needed to relearn the associations each day. With this new apparatus, the number of olfactory cue-reward associations was increased from 2 to 4 in comparison to a previous olfactory tubing maze. Consequently, a supplementary effort of memory was required, and the chance level was decreased from 50 % to 25 %. Thus, in several important respects, the HM can be considered to measure the hippocampus-dependent behaviour of the mouse, allowing to study, as early as possible in young mice, the different subcategories of long-term memory, such as those observed in humans.