Sentence:  Some investigators have found a parallelism between remissions and return of the sympathetic reactivity of the <WSD>hypothalamus</WSD> to the normal level as indicated by the Mecholyl test and , conversely , between clinical impairment and increasing deviation of this test from the norm . 
Meaning of the word marked with <WSD> tags:  a basal part of the diencephalon governing autonomic nervous system