OBJECTIVE: Although it is well established that cerebral activation increases with higher task load, the potential effects of training have been investigated over brief periods only. Training is of potential clinical relevance since training programs are an essential part of psychiatric therapy. METHOD: Cerebral activation during a visual spatial working memory task was examined before, during, and after 4 weeks of daily training in nine healthy subjects using functional magnetic resonance imaging. RESULTS: All subjects showed a pronounced activation mainly involving the right inferior frontal gyrus and the right intraparietal sulcus. While the respective regions showed activation increases with improved performance after 2 weeks of training, the activation values decreased at the time of consolidation of performance gains after 4 weeks. CONCLUSIONS: Our results suggest that training-related cerebral activation changes follow an inverse U-shaped quadratic function and raise the prospect of investigating cerebral mechanisms underlying training effects.