Individual Differences in Radial Maze Performance and Locomotor Activity in the Meadow Vole, Microtus pennsylvanicus

Abstract

Individual differences in the radial maze performance and locomotor activity of wild-caught and first-generation laboratory-born meadow voles are described. Based on their patterns of response in an eight-arm radial maze the essentially wild voles fell into three behavioral categories: 1) strict algorithmic (i.e., they systematically chose the next adjacent arm to their previous choice); 2) nonalgorithmic (i.e., they ran the maze without any consistent or definable pattern); and 3) nonrunners (i.e., nonperformers of the task who remained relatively immobile in the arms of the maze). The algorithmic and nonalgorithmic voles further differed in their responses to an interference manipulation of the radial maze task. Algorithmic individuals displayed a marked performance deficit, while the nonalgorithmic individuals showed minimal disruption to a 1-min delay interruption of the maze task. Measurements of several aspects of locomotor activity using the automated Digiscan activity monitoring system revealed that the algorithmic individuals also displayed significantly greater levels of activity than the nonalgorithmic or nonrunners, with no significant difference in activity between the latter two groups. These findings suggest that the algorithmic voles were relatively inflexible in their behavior, while the nonalgorithmic individuals were more flexible in their maze performance and likely in their use of spatial and nonspatial information. These individual differences in laboratory measures of learning behavior and locomotor activity in meadow voles are consistent with the polymorphism that is proposed to occur in the wild.