To summarize, exposure to drug-related cues mimics the effects of direct drug administration on PFC activity in drug-addicted individuals, although the impact of duration of abstinence and expectation of drug use (and related processes such as forming of drugrelated memories), and their unique contributions to PFC function, remain to be assessed in large sample sizes. By expanding studies of cue reactivity to include additional neuropsychological functions, and by exploring the direction of correlations between PFC activity and specific end-points (for example, craving), the functional significance of activations of specific PFC regions in addiction will become clearer. A further recommendation for future studies into cue reactivity is to conduct direct comparisons between sessions (for example, abstinence versus satiety) and task conditions (for example, drug versus neutral cues) and to perform whole-brain correlations with the respective behavioural changes. Future studies could also compare the duration and the pattern of PFC activation following acute drug exposure and following exposure to conditioned cues in the same subjects. Studies in non-addicted individuals could be used to assess the impact of deprivation (for example, of food)
