My research is concerned with the neural and psychological mechanisms underlying learning, memory, motivation and reward especially related to drug addiction. A major research theme is the impact of learning on drug addiction - both its development and its persistence. Thus, taking drugs might begin as a voluntary, or goal-directed, action but may transform in time to become a compulsive habit that is extremely difficult to relinquish. This transition from initial drug use to addiction may occur through the progressive engagement of different pavlovian and instrumental learning systems in the brain. We have begun to define the neural basis of these learning mechanisms underlying addiction and are also investigating the molecular and neurochemical basis of memory ‘reconsolidation’, the process by which drug and fear (and other memories) become labile when reactivated at retrieval and which holds promise for future treatments of addiction and other neuropsychiatric disorders.