( ( ( A ( neuroleptic 's ) ) potency ) ( ( is ( defined ( by ( its ( ability ( to ( block ( ( the ( ( dopamine type-2 ) ( ( -LRB- ( ( D 2 ) -RRB- ) ) receptors ) ) ) ( in ( ( the striatum ) ( of ( ( the brain ) ( -LRB- ( 3 -RRB- ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (NN neuroleptic) (POS 's)) (NN potency)) (VP (VBZ is) (VP (VBN defined) (PP (IN by) (NP (PRP$ its) (NN ability) (S (VP (TO to) (VP (VB block) (NP (NP (DT the) (ADJP (JJ dopamine) (JJ type-2)) (PRN (-LRB- -LRB-) (NP (NNP D) (CD 2)) (-RRB- -RRB-)) (NN receptors)) (PP (IN in) (NP (NP (DT the) (NN striatum)) (PP (IN of) (NP (NP (DT the) (NN brain)) (PRN (-LRB- -LRB-) (NP (CD 3)) (-RRB- -RRB-)))))))))))))) (. .)))
A neuroleptic's potency is defined by its ability to block the dopamine type-2 (D 2 ) receptors in the striatum of the brain (3).
(ROOT (S (NP (NNP Addiction)) (VP (VBZ affects) (NP (NP (DT the) (JJ dopamine) (NNS receptors)) (PP (IN within) (NP (DT the) (NN brain))))) (. .)))