which may be why it 's so successful at lodging itself in the brain 
(ROOT (SBAR (WHNP (WDT which)) (S (VP (MD may) (VP (VB be) (SBAR (WHADVP (WRB why)) (S (NP (PRP it)) (VP (VBZ 's) (ADJP (RB so) (JJ successful) (PP (IN at) (S (VP (VBG lodging) (NP (PRP itself)) (PP (IN in) (NP (DT the) (NN brain)))))))))))))))
(ROOT (SBAR (WHNP (WDT )) (S (VP (MD ) (VP (VB ) (SBAR (WHADVP (WRB )) (S (NP (PRP )) (VP (VBZ ) (ADJP (RB ) (JJ ) (PP (IN ) (S (VP (VBG ) (NP (PRP )) (PP (IN ) (NP (DT ) (NN )))))))))))))))