Emergence of an egocentric cue guiding and allocentric inferring strategy that mirrors hippocampal brain-derived neurotrophic factor (BDNF) expression in the Morris water maze.

From insects to humans, successful navigation relies on retained representations of spatial relations. These representations are thought to depend on the hippocampal formation, particularly those that are independent of the navigator (allocentric representations). The Morris water maze is a simple and popular task often used to assess spatial navigation. But how animals navigate toward and retain information regarding the location of the goal in this task remains unclear. We provide a comprehensive account of how the water maze is accomplished behaviourally. Our findings suggest that animals solve the task using distal cues via an initial view-matching strategy that is supported by egocentric guidance. Through increased training, however, an emergence of an egocentric-guiding strategy combined with the animal's greater ability to infer the hidden platform's location (via allocentric extrapolation) emerges. We also demonstrate that behavioural changes, towards a more allocentric strategy, are reflected in increases in hippocampal brain-derived neurotrophic factor.