Caffeine and working memory: increase cerebral capacity or demands?
The performance in a N-back task involves multiple hierarchical cognitive processes which heavily depend on different workloads. 0-back, a simple recognition-response task, involves mostly attention, motor control, and inhibition processes without challenging the memory capacity; 2- or more back requires cognitive components recruited in 0-back as well as an increasing memory capacity and continuous information updating. Earlier similar fMRI studies examining acute effects of caffeine using working memory tasks with high versus low-workload contrasts reported an increased task-related activity in the medial frontal region