Although the hormone adrenaline is known to regulate
memory storage, it does not pass from the blood into
brain cells. We are faced with an apparent paradox: how
can a hormone that does not act directly on the brain
have such a large effect on brain function?
Recently, we tested the possibility that one of the
hormone’s actions outside the brain might be responsible.
Since one consequence of adrenaline release in an animal
is an increase in blood glucose levels, we examined the
effects of glucose on memory in rats. We found that glucose
injected immediately after training enhances memory tested
the next day. Additional evidence was provided by negative
findings: drugs called adrenergic antagonists, which block
peripheral adrenaline receptors, disrupted adrenaline’s
ability to regulate memory but did not affect memory
enhancements produced by glucose that was not stimulated
by adrenaline. These results are as they should be if
adrenaline affects memory modulation by increasing blood
glucose levels.
4. The author refers to the results of the experiment using
adrenergic antagonists as “negative findings” (line 13)
most likely because the adrenergic antagonists
(A) failed to disrupt adrenaline’s effect on memory
(B) did not affect glucose’s ability to enhance memory
(C) did not block adrenaline’s ability to increase blood glucose levels
(D) only partially affected adrenaline’s ability to enhance memory
(E) disrupted both adrenaline’s and glucose’s effect on memory
答案是：B
首先,我对文章的理解是这样的
待解释的现象：hormone adrenaline是怎么不和大脑直接作用而影响记忆？
读到这,我就知道文章接下来要说明问号的内容 ： hormone adrenaline -> ? -> 记忆
果然,是因为adrenaline产生葡萄糖 而葡萄糖影响记忆
证据1： 把葡萄糖注入老鼠 记忆up
反向证据2 : 某drug会block adrenaline的接收器 所以无法影响记忆
而且不影响不是由adrenaline产生的葡萄糖
我的问题是 我看不懂证据2的意义在哪？为何他是反向证据
而且证据1已经说明葡萄糖响记忆
那么证据2的"不是由adrenaline产生的葡萄糖”本来就不会被影响阿
为什么”不是由adrenaline产生的葡萄糖不被影响” 这句话却成为反向证据的关键
我不知道我是不理解文章意思还是没有搞懂反向证据的意思
麻烦高手解答
谢谢