Rats’ orientation at the start point is important for spatial learning in a water T-maze

When trained to locate a hidden platform in a T-maze moved between two positions, rats appear to adopt a conditional strategy based on start point discrimination. To determine if location cues or orientation cues at the start point underlie this discrimination, separate groups of rats were trained on two place problems, each with unique start locations at the two maze positions (Experiment 1). The group with the start arms oriented in different directions was more successful than the group with start arms oriented in the same direction. In Experiment 2, rats were trained from two maze positions to swim in a consistent direction from the choice point to the platform. When the maze was later moved to two new positions, rats trained to make the same response based on start point orientation showed no disruption in performance while rats trained to make the same response based on start point location did show an initial disruption in performance. When the start point location cues were masked, by making the room dark prior to placing the rats in the maze, performance did not deteriorate if rats were required to respond based on orientation of the start point but was disrupted if they were required to respond based on start point location cues (Experiment 3). This sense of direction requires exposure to the room cues to get oriented, as rats brought into an already darkened room (Experiment 4) were disrupted regardless of whether responses were tied to orientation cues or location cues. These findings are consistent with views of spatial learning that attribute a strong role to a rats’ sense of direction.

► Orientation at the start point guides responses at the choice point in spatial tasks.
► Distal cues at the start point are not necessary to guide responses at the choice point.
► Some exposure to distal room cues is necessary to maintain a sense of direction.