Exploratory patterns of rats on a complex maze provide evidence for topological coding.

Rats' exploratory patterns on a complex elevated maze were analyzed in both light and dark conditions. Rats were less active in the light than in the dark. In the light, they spent more time exploring the outer areas of the maze than the inner areas whereas exploration of both regions was similar in the dark. In both light and dark, rats spent more time investigating choice points (which provided multiple directions for movements) than runways that allowed only simple movements. In addition, choice points that provided more connections with other distant places were associated with more exploration. While such effects might be the result of stimulus-seeking of distant information in the light, increased exploration times in the dark presumably reflect the processing of local information associated with the maze connectivity. These results suggest that exploratory patterns in the dark reflect processing of the topological structure of the maze.