Cover picture: Ventrolateral frontal and left medial temporal structures release dopamine when people are engaged in a verbal working memory task. The hot colors indicate changes during working memory performance in the binding potential of a high-affinity dopamine D₂ receptor tracer [¹¹C]FLB 457 as measured by positron emission tomography (PET). The stimulus sequence is illustrated in the background. Single letters appear one after another, and the subject should press the "yes" button when the letter is the same as two letters back (e.g., R-k-r). These findings indicate regionally specific dopamine release in verbal working memory and show a noninvasive PET approach for the study of involvement of cortical dopamine neurotransmission in cognitive functions in healthy humans. For details, see the article by Aalto et al. in the issue (pages 2471–2477.