( ( ( receptors , ) dopamine ) ; )
(ROOT (NP (NP (NNS receptors)) (, ,) (NP (NN dopamine)) (: ;)))
receptors, dopamine;
(ROOT (S (NP (NNP Addiction)) (VP (VBZ affects) (NP (NP (DT the) (JJ dopamine) (NNS receptors)) (PP (IN within) (NP (DT the) (NN brain))))) (. .)))