愛思唯爾期刊《學習與記憶神經生物學》(Neurobiology of Learning and Memory)在線發(fā)表了美國芝加哥大學的一項最新研究,，研究發(fā)現體內皮質醇含量適中的松鼠在學習和適應環(huán)境等方面都比含皮質醇偏高或是偏低的松鼠強,。
皮質醇是腎上腺在應激反應里產生的一種類激素,，壓力狀態(tài)下身體需要皮質醇來維持正常生理機能,。研究中研究人員模擬出一個與松鼠窩相連的自然迷宮以探測其辨別能力,，同時研究人員人為地改變了一些松鼠的體內皮質醇含量,。結果發(fā)現,，體內皮質醇含量適中的松鼠用9次會找到它們的“家”,，而對于那些皮質醇含量偏高或偏低的松鼠則平均都需要13至14次的嘗試才能做到,。同時，研究人員還對體內皮質醇含量的不同的松鼠對應險情能力方面做了測試,，研究發(fā)現同樣皮質醇含量適中的松鼠能力要強,。
目前，對于人體內皮質醇偏低會如何影響其學習方面還尚不清楚,?？茖W家希望動物體內皮質醇含量對其學習方面的影響，能夠對研究人體皮質醇水平對人學習能力的影響有所啟發(fā),。（科學網 于乃森/編譯）
生物谷推薦原始出處：
(Neurobiology of Learning and Memory),，doi:10.1016/j.nlm.2007.11.002，Jill M. Mateo
Inverted-U shape relationship between cortisol and learning in ground squirrels
Jill M. Mateo, a,
aDepartment of Comparative Human Development & The Institute for Mind and Biology, 5730 South Woodlawn Avenue, The University of Chicago, Chicago, IL 60637, USA
Received 16 October 2007; revised 18 November 2007; accepted 19 November 2007. Available online 4 March 2008.
Abstract
Adrenal hormones regulate glucose levels, responses to unpredictable stressors and modulate cognition. Glucocorticoids can have an inverted-U shape relationship with cognition, as very low or high levels impair, whereas moderate elevations facilitate, acquisition and retention of memories. To date these relationships have been tested with humans and rodents in laboratory settings rather than with wild animals in biologically relevant contexts. This study examined whether the elevated cortisol observed in juvenile Belding’s ground squirrels (Spermophilus beldingi) at natal emergence might promote both acquisition of adaptive responses to this species’ two alarm calls warning of predators and memory of the spatial configuration of mothers’ territories. Both experimentally increased and decreased basal cortisol levels interfere with acquisition and retention of an association between a warning call and the appropriate response compared with naturally occurring moderately elevated cortisol. Further, decreased cortisol impairs learning of a novel, complex spatial maze. Thus in the field the brief elevation of cortisol at emergence might facilitate acquisition of spatial memory of a three-dimensional environment and responses to alarm calls during a sensitive period of learning. This novel demonstration of the inverted-U shape function in a wild animal suggests that natural selection has favored a hormonal profile facilitating rapid acquisition of important survival behaviors.
