练习材料：
Lesson 19-2 The stuff of dreams
If it is not a question of resting the body, then perhaps it is the brain that needs resting? This might be a plausible hypothesis were it not for two factors. First the electroencephalograph (which is simply a device for recording the electrical activity of the brain by attaching electrodes to the scalp) shows that while there is a change in the pattern of activity during sleep, there is no evidence that the total amount of activity is any less. The second factor is more interesting and more fundamental. Some years ago an American psychiatrist named William Dement published experiments dealing with the recording of eye-movements during sleep.
如果睡眠的功能不是在于使身体得到休息，那么也许是让大脑得以休息？若不是下面两点，这种假使似乎是有道理的。第一点，脑电图记录仪（不过是一种把电极接到头皮上记录脑电活动的仪器）显示，人在睡眠时大脑活动的方式有变化，但没有迹象表明，其活动总量有任何减少。第二点更有意思，也更重要。前些年，美国一位精神病学者发表了一篇报告，报告中记录了眼球在睡眠时的活动情况。
任务配置：L0、L3、L4
练习感悟：完成底限任务。
