( ( The elimination ) ( ( is ( driven ( by ( competition ( between ( ( neurons , ) ( which ( ( in turn ) ( is ( governed ( by ( ( the ( ( activity or ) use ) ) ( of ( neural circuits ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN elimination)) (VP (VBZ is) (VP (VBN driven) (PP (IN by) (NP (NP (NN competition)) (PP (IN between) (NP (NP (NNS neurons)) (, ,) (SBAR (WHNP (WDT which)) (S (PP (IN in) (NP (NN turn))) (VP (VBZ is) (VP (VBN governed) (PP (IN by) (NP (NP (DT the) (NN activity) (CC or) (NN use)) (PP (IN of) (NP (JJ neural) (NNS circuits))))))))))))))) (. .)))
The elimination is driven by competition between neurons, which in turn is governed by the activity or use of neural circuits.
(ROOT (S (NP (NP (QP (DT Half))) (PP (IN of) (NP (NP (DT the) (NNS neurons)) (VP (VBN formed) (PP (IN in) (NP (DT the) (NN embryo))))))) (VP (VBP are) (VP (VBN eliminated) (PP (RB because) (IN of) (NP (NN competition)))))))