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 mediatio n of spatially related behaviors in male and female laboratory rats. M eadow voles, Microtus pennsylvanicus, are dirunally-crepuscularly acti ve microtine rodents that exhibit a variety of sexually dimorphic spat ially associated behaviors in both the laboratory and wild. In the pre sent study we examined both the spatial Morris water maze performance and dendritic architecture and branching of neuronal cells in the pref rontal and parietal cortex of reproductive male and female meadow vole s. 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 wi th Golgi-Cox stained sections showed that male voles had significantly more dendritic arborization in the medial prefrontal and parietal cor tex than females. These sex differences in both spatial navigation abi lity and in neural structures related to spatial navigation in meadow voles suggest that the size of neural areas might be shaped by ecologi cal pressures associated with sexually dimorphic spatial behaviors. (C ) 1998 Elsevier Science B.V. All rights reserved.