The study will last for approximately 4 weeks but could be up to 6 weeks, depending on length of time between screening and dosing. From screening the subjects will be alcohol-abstinent, they may be put on medication for treatment of withdrawal symptoms and then will have at least 7 days without any medication before beginning the study medication. During the study the subjects will be inpatients at the Central Institute of Mental Health. All subjects will be required to fill out questionnaires, perform behavioural tasks and undergo MRI and functional MRI (fMRI) scans.