The neural basis of learning and memory
mechanisms underlying drug addiction
Drug
addiction is increasingly viewed as the endpoint of a series of transitions from
initial drug use, when a drug is voluntarily taken because it has
reinforcing, often hedonic, effects through loss of control over this
behaviour such that it becomes habitual and ultimately compulsive
in nature. In this lecture I will discuss the evidence that these
transitions depend upon interactions between pavlovian and
instrumental learning processes and further, that the transition from an
initial stage when drug seeking and taking represents a
voluntary, goal-directed action, to a more habitual and compulsive mode
represents a transition at the neural level from prefrontal cortical
to striatal control over such behaviour. Experiments will be
discussed that demonstrate the involvement of limbic
corticostriatal systems in drug-seeking behaviour, emphasizing the importance of
drug-associated stimuli acting as conditioned reinforcers. In
addition, I will consider the possibility of reducing the
motivational impact of drug-associated stimuli by disrupting the
process of memory reconsolidation that point to a novel therapeutic
approach to drug addiction by promoting abstinence and preventing
relapse. |
