适度应激有助于提高学习效率

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Stress helps you learn better

17 Mar 2008, 2114 hrs IST,IANS

NEW YORK: There is no harm in a bit of stress - in fact, it helps you learn things better. At least that's how it is among squirrels, says a new study.

University of Chicago researchers who conducted the study found that squirrels learn more quickly while carrying out survival tasks if they have modest

levels of cortisol, a hormone produced in response to stress.

In humans, cortisol production is linked to stress and is known to impact learning, but the process is not well understood, said lead researcher Jill Mateo.

The research on squirrels could open up more avenues of research.

The results of the study have been published in the latest edition of the journal Neurobiology of Learning and Memory.

Squirrels must learn how to cope with the dangers of their environment to find their way back to their homes. The pups emerge from their nests about the time

they're weaned, at four weeks.

\"Two hundred can emerge at the same time, providing a feast for predators,\" said Mateo. About 30 percent of pups do not survive.

In order to test whether animals with low levels have difficulty learning, Mateo altered the amount of cortisol in the pups' systems and found that those

with both high and low cortisol levels took an average of 13 to 14 trials before navigating a maze, while the group of non-treated pups needed just nine.

She tested the animals' response to danger by throwing a frisbee over the maze and also by sounding a birdcall to see how quickly the pups responded. High

and low amounts of cortisol reduced the animals' ability to learn how to respond to danger.

The animal tests also help to understand the potential human impact of low cortisol on learning, she said.

美国研究人员最近一项动物研究表明，适度应激有助于提高学习效率。

该研究的主要作者Jill Mateo说，人们都知道皮质醇的产生与应激有关，且对学习能力有一定影响，但其中的具体机制尚不十分清楚，对松鼠的研究可以开辟更多新的研究途径。上述研究结果发表在最新出版的《学习与记忆神经生物学》杂志。

芝加哥大学的研究人员通过对松鼠的试验研究发现，松鼠在执行生存任务时如果体内应激状态产生的激素——皮质醇保持一定的水平，它们的学习速度会明显加快。

松鼠必须学会如何应对周围环境中的危险，才能找到回家的路。小松鼠通常在只有四周大的时候就断奶，离开他们的巢穴。 Mateo介绍说，“同一时间可以有200只松鼠离开巢穴，这对食肉动物来说，简直就是一场盛宴。通常，30 ％的小松鼠都无法从危险中生存下来。

Mateo人为改变小松鼠体内的皮质醇水平，以明确是否皮质醇水平低的松鼠学习能力也会下降。结果发现，皮质醇水平过高和过低的松鼠平均需要13～14次试验才能走出迷宫，而未经处理过的小松鼠只需9次就能学会。Mateo还将一枚飞盘扔到迷宫上方，用来测试松鼠对险情的反应，并发出鸟叫声观察松鼠的反应速度。较高和较低量的皮质醇都会降低动物应对危险的学习能力。

Mateo说，动物试验结果也有助于理解皮质醇水平过低对人类学习能力的潜在影响。