Sentence:  Important as these differences are , they should not obscure the basic fact that by shifting the hypothalamic balance sufficiently to the parasympathetic <WSD>side</WSD> , we produce depressions , whereas a shift in the opposite direction causes excitatory effects and , eventually , maniclike changes . 
Meaning of the word marked with <WSD> tags:  a place within a region identified relative to a center or reference location