By 1950, the results of attempts to relate brain processes to mental experience appeared rather discouraging. Herring suggested that different modes of sensation, such as pain, taste, and color, might be correlated with the discharge of specific kinds of nervous energy. However, subsequently developed methods of recording and analyzing nerve potentials failed to reveal any such qualitative diversity. Although qualitative variance among nerve energies was never rigidly disproved, the doctrine was generally abandoned in favor of the opposing view, namely, that nerve impulses are essentially homogeneous in quality and are transmitted as common currency throughout the nervous system.
According to this theory, it is not the quality of the sensory nerve impulses that determines the diverse conscious sensations they produce, but rather the different areas of the brain into which they discharge, and there is some evidence for this view. In one experiment, when an electric stimulus was applied to a given sensory field of the cerebral cortex of a conscious human subject, it produced a sensation of the appropriate modality for that particular locus, that is, a visual sensation from the visual cortex, an auditory sensation from the auditory cortex, and so on. However, cortical locus, in itself, turned out to have little explanatory value.
1. The author mentions common currency primarily in order to emphasize the
A. lack of differentiation among nerve impulses in human beings
B. similarity of the sensations that all human beings experience
C. similarities in the views of scientists who have studied the human nervous system
D. continuous passage of nerve impulses through the nervous system
E. recurrent questioning by scientists of an accepted explanation about the nervous system
解析：原句翻译：神经冲动本质上质量相似，并在神经系统中流通传输。通过语法分析，我们可以知道common currency与前面的从句成分nerve impulses are essentially homogeneous in quality是并列的，主语都是nerve impulses，并且common和前面的homogeneous都是在讲相似，差异小。
2. The description of an experiment in which electric stimuli were applied to different sensory fields of the cerebral cortex tends to support the theory that
A. the simple presence of different cortical areas cannot account for the diversity of mental experience
B. variation in spatiotemporal patterning of nerve impulses correlates with variation in subjective experience
C. nerve impulses are essentially homogeneous and are relatively unaffected as they travel through the nervous system
D. the mental experiences produced by sensory nerve impulses are determined by the cortical area activated
E. variation in neuron types affects the quality of nerve impulses
解析：定位到文章：可以直接得出答案“it produced a sensation of the appropriate modality for that particular locus, that is, a visual sensation from the visual cortex“电刺激能产生一种对特定位置的恰当的感知，也就是视觉中枢的视觉感知。和D选项的cortical area脑皮层被刺激使神经产生精神反应对应。
3. Which of the following best summarizes the author‘s opinion of the suggestion that different areas of the brain determine perceptions produced by sensory nerve impulses?
A. It is a plausible explanation, but it has not been completely proved.
B. It is the best explanation of brain processes currently available.
C. It is disproved by the fact that the various areas of the brain are physiologically very similar.
D. There is some evidence to support it, but it fails to explain the diversity of mental experience.
E. There is experimental evidence that confirms its correctness.
解析：结合结尾句：However, cortical locus, in itself, turned out to have little explanatory value.大脑区位理论就其本身是几乎没有解释的意义，说明其解释的价值和意义还是有限的。