Ferkin Michael H, Pierce Andrew A, Sealand Robert O
The University of Memphis, Biology Department, Ellington Hall, Memphis, TN 38152, USA.
Horm Behav. 2009 Jan;55(1):76-83. doi: 10.1016/j.yhbeh.2008.08.010. Epub 2008 Sep 10.
Animals in a variety of taxa discriminate between a greater quantity and a lesser quantity of the same object, an ability that is referred to as relative numerousness judgment. For example, meadow voles can distinguish between areas containing more over-marks by one opposite-sex scent donor and fewer over-marks by another opposite-sex scent donor. Females appear to be able to make better discriminations between more or less over-marks than do males. In that gonadal hormones have been implicated in modulating cognitive function associated with spatial tasks, we tested the hypothesis that high titers of testosterone and estradiol are necessary for male and female voles, respectively, to distinguish between the top- and bottom-scent donors in an area containing mixed over-marks. We gonadectomized voles, giving them either gonadal hormone replacement (testosterone for males and estradiol for females) or no hormone replacement, and tested their spontaneous judgments of distinguishing between the top- and bottom-scent donors in an area containing mixed over-marks; a task involving judgments of relative numerousness. Female voles given replacement estradiol performed better than did female voles not given replacement estradiol in determining the top-scent and bottom-scent males in areas containing mixed over-marks. In contrast, males not treated with replacement testosterone performed better than did males treated with testosterone in determining the top-scent and bottom-scent males in areas containing mixed over-marks. Thus, high titers of estradiol and low titers of testosterone are associated with better performance on tasks involving relative numerousness in female and male voles, respectively. The results of this task on relative numerousness judgments are discussed in relation to the effects of gonadal steroid hormone on spatial ability, a closely related cognitive domain, and the social biology of meadow voles.
多种分类群的动物能够区分同一物体的较多数量和较少数量，这种能力被称为相对数量判断。例如，草甸田鼠能够区分由一个异性气味提供者留下更多标记的区域和由另一个异性气味提供者留下较少标记的区域。雌性似乎比雄性能够更好地区分标记的多少。鉴于性腺激素与调节与空间任务相关的认知功能有关，我们测试了这样一个假设，即高浓度的睾酮和雌二醇分别是雄性和雌性田鼠区分含有混合标记区域中顶部和底部气味提供者所必需的。我们对田鼠进行了性腺切除，给它们提供性腺激素替代物（雄性用睾酮，雌性用雌二醇）或不进行激素替代，然后测试它们在含有混合标记区域中区分顶部和底部气味提供者的自发判断；这是一项涉及相对数量判断的任务。在含有混合标记的区域中，接受雌二醇替代的雌性田鼠在确定顶部气味和底部气味雄性方面比未接受雌二醇替代的雌性田鼠表现更好。相反，在含有混合标记的区域中，未接受睾酮替代治疗的雄性在确定顶部气味和底部气味雄性方面比接受睾酮治疗的雄性表现更好。因此，高浓度的雌二醇和低浓度的睾酮分别与雌性和雄性田鼠在涉及相对数量任务中的更好表现相关。关于相对数量判断这项任务的结果，将结合性腺类固醇激素对空间能力（一个密切相关的认知领域）的影响以及草甸田鼠的社会生物学进行讨论。
