What makes a landmark effective in adolescent and adult rats? Sex and age differences in a navigation task

Abstract

In three experiments, rats of different ages were trained in a circular pool to find a hidden platform whose location was defined in terms of a single landmark, a cylinder outside the pool. Following training, two main components of the landmark, its shape and pattern, were tested individually. Experiment 1 was performed by adolescent and adult rats (Exp. 1a, males; Exp. 1b, females). Adult rats always learned faster than the adolescent animals. On test trials, interesting tendencies were found-mainly, one favoring males on the shape test trial, and another favoring females on the pattern test trial. Experiment 2 was conducted only with adolescent rats, and these males and females did not differ when learning the task. However, on test trials the males learned more about the landmark shape component than about the landmark pattern component, while the females learned equally about the two components of the landmark. Finally, Experiment 3 was conducted only with adult rats, and again the males and females did not differ when learning the task. However, on test trials the males learned equally about the two components of the landmark (shape and pattern), but the females learned more about the landmark pattern component than about the landmark shape component. This set of experiments supports the claim that male and female rats can learn rather different things about a landmark that signals the location of the platform, with age being a critical variable.

Geometry learning while navigating: The importance of task difficulty and sex differences.

“…Answering this question is important because it has been shown, in rodents and in humans, that when trained to find a hidden goal in the presence of geometrical and nongeometrical cues, in the two species mentioned, males seem more likely to rely on geometrical information to reach the goal, while females are more likely to use landmarks (in rats, see Rodríguez, Torres, Mackintosh, & Chamizo, 2010; Williams, Barnett, & Meck, 1990; in humans, Sandstrom, Kaufman, & Huettel, 1998; Ward, Newcombe, & Overton, 1986). Moreover, even when only landmark learning is addressed, males seem to learn different things than females about a single landmark that signals the location of a hidden platform (Chamizo, Rodríguez, Torres, Torres, & Mackintosh, 2014; Chamizo, Torres, Rodríguez, & Mackintosh, 2019).…”