( ( ( ( ( The brain ) ( ( , ( ( he says ) , ) ) ( is ( ( the ( ( ( ( most complex ) and ) least ) ( understood parts ) ) ) ( of ( the ( human body ) ) ) ) ) ) ) and ) ( ( studying ( ( the way ) ( it ( works ( in weightlessness ) ) ) ) ) ( will ( be ( ( the focus ) ( for ( the ( entire mission ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN brain)) (PRN (, ,) (S (NP (PRP he)) (VP (VBZ says))) (, ,)) (VP (VBZ is) (NP (NP (DT the) (ADJP (ADJP (RBS most) (JJ complex)) (CC and) (ADJP (JJS least))) (JJ understood) (NNS parts)) (PP (IN of) (NP (DT the) (JJ human) (NN body)))))) (CC and) (S (S (VP (VBG studying) (NP (NP (DT the) (NN way)) (SBAR (S (NP (PRP it)) (VP (VBZ works) (PP (IN in) (NP (NNS weightlessness))))))))) (VP (MD will) (VP (VB be) (NP (NP (DT the) (NN focus)) (PP (IN for) (NP (DT the) (JJ entire) (NN mission))))))) (. .)))
The brain, he says, is the most complex and least understood parts of the human body and studying the way it works in weightlessness will be the focus for the entire mission.
(ROOT (S (NP (DT The) (NN brain)) (VP (VBZ is) (NP (NP (DT the) (ADJP (RBS most) (JJ complex)) (NN organ)) (PP (IN in) (NP (DT the) (JJ human) (NN body))))) (. .)))