I would like to discuss the phrase: The left and right cerebral hemisphere(s?) is/are(?) responsible for rational thinking and creativity, respectively. I know that respectively requires parallelism. But do I have to think of two separate sentences like The left cerebral hemisphere is responsible for rational thinking and the right cerebral hemisphere is responsible for creativity. In this case, I would guess that I would have to use "hemisphere" in singular and the verb "is". Or do I have to think of the whole are one phrase and use plural in both places? Using plural in both places might be misleading till the reader arrives at "respectively". He may think that both hemispheres are responsible for both.