专八阅读训练：Brain Process and Mental Experience

The Relationship between Brain Process with Mental Experience

By 1950, the results of attempts to relate brain processesto mental experience appeared rather discouraging. Suchvariations in size, shape, chemistry, conduction speed, excitationthreshold, and the like as had been demonstrated in nerve cellsremained negligible in significance for any possible correlationwith the manifold dimensions of mental experience.

Near the turn of the century, it had been suggested by Hering that different modes of sensation,such as pain, taste and color, might be correlated with the discharge of specific kinds of nervousenergy, However, subsequently developed methods of recording and analyzing nerve potentialsfailed to reveal any such qualitative diversity. It was possible to demonstrate by other methodsrefined structural differences among neuron types; however, proof was lacking that the quality ofthe impulse or its conduction was influenced by these differences, which seemed instead toinfluence the developmental patterning of the neural circuits. Although qualitative variance amongnerve 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 qualityof 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 evidencefor this view. In one experiment, when an electric stimulus was applied to a given sensory field ofthe cerebral cortex of a conscious human subject, it produced a sensation of the appropriatemodality for that particular locus, that is, a visual sensation from the visual cortex, an auditorysensation from the auditory cortex, and so on. Other experiments revealed slight variations in thesize, number, arrangement, and interconnection of the nerve cells, but as for as psychoneuralcorrelations were concerned, the obvious similarities of these sensory fields to each other seemedmuch more remarkable than any of the minute differences.

However, cortical as diverse as those of red, black, green and white, or touch, cold, warmth,movement, pain, posture and pressure apparently may arise through activation of the samecortical areas. What seemed to remain was some kind of differential patterning effects in the brainexcitation: it is the difference in the central distribution of impulses that counts. In short, Braintheory suggested a correlation between mental experience and the activity of relativelyhomogenous nerve-cell units conducting essentially homogeneous impulses throughhomogeneous cerebral tissue. To match the multiple dimensions of mental experiencepsychologists could only point to a limitless variation in the spatiotemporal patterning of nerveimpulses.

1. Up until 1950, efforts to establish that brain processes and mental experience are related wouldmost likely have been met with
[A] vexation [B] irritability [C] discouragement [D] neutrality

2. The author mentions “common currency” primarily in order to emphasize the
[A] lack of differentiation among nerve impulses in human beings.
[B] similarities in the views of the scientists.
[C] similarity of sensations of human beings.
[D] continuous passage of nerve impulses through the nervous system.

3. Which of the following theories is reinforced by the depiction of the experiment in lines 16—19?
[A] Cognitive experience manifested by sensory nerve impulses are influenced by the area of thebrain stimulated.
[B] Qualitative diversity in nerve potentials can now be studied more accurately.
[C] Sensory stimuli are heterogeneous and are greatly influenced by the nerve sensors theyproduce.
[D] Differentiation in neural modalities influences the length of nerve transmissions.

4. It can be inferred from the passage that which of the following exhibit the LEAST qualitativevariation?
[A] Nerve cells.     [B] Nerve impulses.
[C] Cortical areas. [C] Spatial patterns of nerve impulses.