Evidence for 24-hour memory retention in radial maze performance by rats: an examination controlling for possible odor cues

Abstract

The present study examined memory retention over 24 hours in rats’ performance in a radial maze. Crystal & Babb (2008) demonstrated that rats can retain spatial memory for up to 25 hours in a radial maze, but these findings had not been reexamined until now. Therefore, the primary objective of our study was to replicate the results reported by Crystal & Babb (2008). Each trial included a learning phase, during which subjects were required to sequentially visit four randomly selected arms, followed by a free-choice test that encompassed all eight arms after a retention interval. Although Crystal & Babb cleaned the arms of the maze with Nolvasan solution during the retention interval, they did not conduct further controls for potential odor cues left by markings to identify unvisited baited arms. Consequently, the second objective of our study was to eliminate the possibility of the results being influenced by such odor cues. To achieve this, we covered touchable parts of the maze, including the arms and the platform, and alternated these covers among the arms, while also rotating the cover on the platform during the retention interval. Performance significantly exceeded chance levels under the 24-hour retention interval, demonstrating that rats can retain spatial memory for 24 hours, thus replicating the findings of Crystal & Babb (2008) without the influence of odor cues marked in the maze.