title: Performance (re-acquisition) of a water-maze task by adult meadow voles: effects of age of initial task acquisition and in utero environment (litter sex-ratio).
abstract: Previous research in this laboratory has shown that preweaning and postweaning juvenile meadow voles, Microtus pennsylvanicus, can acquire a spatial task, the Morris water-maze task. The present study examined the influence of age of juvenile acquisition ("before weaning" (BW; Day 10 and 15 after birth) and "after weaning" (AW; Day 20 and 25 after birth)) of a spatial task on subsequent re-acquisition of the same hidden-platform spatial water-maze task. This study also compared sex differences and litter sex-ratio effects on reacquisition performance. Fifteen litters of adults were re-tested in the same water maze 6 weeks after being initially tested as juveniles. All analyses were conducted using a covariate that removed the group differences in the original task performance. Adult voles from female-biased litters, that had previously learned the task at an older juvenile age (AW), reacquired the same task faster than adults that had previously learned the task at a younger juvenile age (BW). In the adult BW group there was also a significant litter sex-ratio effect such that voles born into a female-biased litter re-acquired the task more slowly than did voles born into a male-biased litter. There were no significant sex or litter sex-ratio effects on spatial learning in the AW group. These results show that adult meadow voles can require a spatial task more quickly if they initially learned the task at an older juvenile age, suggestive of a period of infantile amnesia. In addition, these results indicate that the litter sex-ratio can affect adult spatial performance, suggesting that the relative amount of androgens in utero may influence the development of sexually-dimorphic spatial ability in adulthood.
authors.affiliation: Neuroscience Program, University of Western Ontario, London, Canada.
authors.forename: L A
authors.initials: LA
authors.lastname: Galea
authors.forename: K P
authors.initials: KP
authors.lastname: Ossenkopp
authors.forename: M
authors.initials: M
authors.lastname: Kavaliers
mesh_terms: D000728:Androgens / Q000502:physiology; D000818:Animals; D003411:Arvicolinae; D004924:Escape Reaction / Q000502:physiology*; D005260:Female; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D009949:Orientation / Q000502:physiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012153:Retention, Psychology / Q000502:physiology; D012733:Sex Differentiation / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology*
chemical_list: D000728:Androgens