He was responding inappropriately to questions (i.e. saying "no" when he meant to say "yes"), but appeared to understand what was being said to him.
 The patient has expressive dysphasia. 
(ROOT (S (NP (PRP He)) (VP (VP (VBD was) (VP (VBG responding) (ADVP (RB inappropriately)) (PP (TO to) (NP (NP (NNS questions)) (PRN (-LRB- -LRB-) (PP (FW i.e.) (S (VP (VBG saying) (`` ``) (NP (DT no) ('' '') (SBAR (WHADVP (WRB when)) (S (NP (PRP he)) (VP (VBD meant) (S (VP (TO to) (VP (VB say) (INTJ (`` ``) (UH yes) ('' '')))))))))))) (-RRB- -RRB-)))))) (, ,) (CC but) (VP (VBD appeared) (S (VP (TO to) (VP (VB understand) (SBAR (WHNP (WP what)) (S (VP (VBD was) (VP (VBG being) (VP (VBD said) (PP (TO to) (NP (PRP him))))))))))))) (. .)))
(ROOT (S (NP (DT The) (NN patient)) (VP (VBZ has) (NP (JJ expressive) (NN dysphasia))) (. .)))
( He ( ( ( ( ( was ( ( responding inappropriately ) ( to ( questions ( -LRB- ( ( i.e. ( ( saying `` ) ( ( no '' ) ( when ( he ( meant ( to ( say ( `` ( yes '' ) ) ) ) ) ) ) ) ) ) -RRB- ) ) ) ) ) ) , ) but ) ( appeared ( to ( understand ( what ( was ( being ( said ( to him ) ) ) ) ) ) ) ) ) . ) )
( ( The patient ) ( ( has ( expressive dysphasia ) ) . ) )