Over the past year, we have developed a variety of cognitive tasks for functional neuroimaging in PET and MRI. 1. We have developed a spatial delayed response task that involves maintaining non-verbal information over short delays. PET activation was noted in a physically distributed neural network that included prefrontal cortex, occipital cortex, and supplementary motor cortex. 2. We have developed a verbal fluency paradigm which involves paced fluency for phonologic materials (i.e., the subject is asked to say as many words beginning with a given letter as possible in comparison to semantic fluency (the subject is requested to state as many semantic exemplars of a given category as possible). We found PET activation for phonologic fluency in Broca's area and Wernicke's area in the left hemisphere. We found relatively greater activation for semantic fluency in the superior temporal lobe. Both fluency paradigms also demanded prefrontal and cingulate activity, perhaps in relationship to retrieval. 3. We have developed continuous working memory task in which numeric information must be maintained over short delays in the face of interference. In this task, the subject must respond to a number that had been previously present, but was no longer present on the screen as a continuous set of numbers is presented. In this task, there are "one back and two back" conditions in order to manipulate difficulty. 4. A dual task interference paradigm was developed in order to assess whether marked increases in difficulty level produce greater activation in a given region or less activation in a given region. Preliminary results indicated that the cerebellum may participate in dual tasks, perhaps, in relationship to a "time-sharing" function. 5. A rapid finger tapping procedure in the context of a video game will be used in order to activate dopaminergic neurons in the hope of producing activation in basal ganglia regions due to dopaminergic neuronal activity.