Sex differences in spatial learning and prefrontal and parietal cortical dendritic morphology in the meadow vole, Microtus pennsylvanicus.

The prefrontal and parietal cortex has been implicated in the mediation of spatially related behaviors in male and female laboratory rats. Meadow voles, Microtus pennsylvanicus, are diurnally-crepuscularly active microtine rodents that exhibit a variety of sexually dimorphic spatially associated behaviors in both the laboratory and wild. In the present study we examined both the spatial Morris water maze performance and dendritic architecture and branching of neuronal cells in the prefrontal and parietal cortex of reproductive male and female meadow voles. Males learned the location of the hidden platform in the water task faster than estrous females and on probe trials they spent more time in the previously correct quadrant than females. Dendritic analysis with Golgi-Cox stained sections showed that male voles had significantly more dendritic arborization in the medial prefrontal and parietal cortex than females. These sex differences in both spatial navigation ability and in neural structures related to spatial navigation in meadow voles suggest that the size of neural areas might be shaped by ecological pressures associated with sexually dimorphic spatial behaviors. Copyright 1998 Elsevier Science B.V.