target trial N − 1 from the interfering trial N − 2. Thus, the target information required for successful performance varies from trial to trial, so that the subject is not only required to temporarily keep specific information in short-term storage but also reset it over successive runs. The resetting mechanisms and cognitive flexibility required to alternate over successive runs are major components of working memory processes. Working memory is a component of the sequential alternation task, since spontaneous alternation rates are dependent on the length of the inter-trial delay interval and/or the place of the trial in the series. Indeed, repetitive testing constitutes a potent source of proactive interference. Thus, the sequential alternation procedure is relevant to assess delay-dependent working memory in mice (50–52). Using in vivo microdialysis in freely moving mice, we observed that early (1 week) and protracted (6 weeks) withdrawal periods from prolonged (6 months) alcohol exposure causes an exaggerated corticosterone rise in the medial PFC. In addition, withdrawn mice having abnormal corticosterone concentration in the PFC displayed impaired working memory performance, effects that were not observed in animals still submitted to chronic alcohol consumption. Moreover, early and protracted withdrawal periods had no effect on the
