Sentence:  Furthermore , conditioned reactions are fundamentally altered when the hypothalamic sympathetic reactivity is augmented beyond a critical level , and <WSD>several</WSD> types of behavioral changes probably related to the degree of central autonomic `` tuning '' are observed . 
Meaning of the word marked with <WSD> tags:  (used with count nouns) of an indefinite number more than 2 or 3 but not many