The primary objective of this study is to investigate the safety and tolerability of AZD1704 following single ascending doses in healthy Japanese male and non-fertile female volunteers by assessment of adverse events (AEs), vital signs (supine and standing blood pressure, pulse rate, respiratory rate and body temperature), safety laboratory variables and 12 lead electrocardiography (ECG). The secondary objectives of the study are: to investigate the subjective CNS effects of orally administered AZD1704 in healthy Japanese male and non-fertile female volunteers on a psychometric rating scale by assessment of specific adjectives (stimulated, anxious, sedated, down and high) rated on visual analogue mood scale (VAMS) and to investigate the pharmacokinetic profile of AZD1704 following single ascending doses in healthy Japanese male and non-fertile female volunteers.