FUNCTIONAL MAGNETIC-RESONANCE-IMAGING IN THE ACTIVATION OF WORKING-MEMORY

Aims: Functional magnetic resonance imaging was used in conjunction wi th a letter detection task for the study of working memory in 16 norma l subjects. Because of movement artifacts, data from only 9 subjects w ere analysed. Methods: In the activation task, subjects responded by p ressing a button whenever any presented letter was the same as the sec ond last in the sequence. In the control condition, the subjects had t o respond to a fixed letter. Hence, the activation condition and the c ontrol condition differed only subjectively, i.e., regarding the task demand, whereas the stimuli and the type and frequency of response wer e identical. Results: The activation condition produced significant ac tivation in the dorsolateral prefrontal cortex (Brodmann's areas 10, 4 6, and 9). Conclusions: In contrast to experimental tasks previously u sed rather extensively to study the prefrontal cortex, the present par adigm is characterized by its simplicity, interpretability, and its ti es to known neurophysiology of the frontal cortex.