( ( In ( the brain ) ) ( ( the ( white matter ) ) ( ( lies ( within ( ( the ( gray layer ) ) ( of ( the ( cerebral cortex ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN In) (NP (DT the) (NN brain))) (NP (DT the) (JJ white) (NN matter)) (VP (VBZ lies) (PP (IN within) (NP (NP (DT the) (JJ gray) (NN layer)) (PP (IN of) (NP (DT the) (JJ cerebral) (NN cortex)))))) (. .)))
In the brain the white matter lies within the  gray layer of the cerebral cortex.
(ROOT (S (NP (NP (JJS Most)) (PP (IN of) (NP (DT the) (JJ gray) (NN matter)))) (VP (VBZ is) (PP (IN on) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (DT the) (NN brain))))) (, ,) (S (VP (VBG surrounding) (NP (JJ white) (NN matter))))) (. .)))