Limitations on Spatial Memory in Mice

Rats have an impressive ability to remember locations they have visited. Two experiments used an eight-arm radial maze to determine whether mice showed two important characteristics of this spatial memory: its durability, and its dependence on stimuli outside the maze (extreme stimuli). In Experiment 1, food-deprived mice were allowed to eat from four of the eight arms of the maze then, after delays of 5 sec, 1 min, or 5 min, they were permitted to choose the remaining arms. Choice accuracy declined significantly with the longer delays, but always remained above chance. In Experiment 2, the maze was rotated 180° after four choices had been made, then subjects chose the rest of the arms. The mice relied primarily on extramaze cues for selecting arms, although some subjects exhibited considerable response patterning. As other studies have suggested, the rat's impressive spatial memory may not be shared by other species, even other rodents.