求助36套中exercise 2 的一道题目

nuinuiUID: 3129830

原文定位：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.
答案：There is some evidence to support it, but it fails to explain the diversity of mental experience.

疑惑： 答案的前半句能懂后半句怎么就能出来了diversity呢？很多解答上只说了后面有作者的负态度 所以就转折，可是转折后的宾语都哪儿来的呀？而且个人感觉最后一句however， 表达的是没有解释的必要， 为什么是缺陷呢？