Over the past year, we have developed and tested a variety of cognitive tasks for functional neuroimaging and PET NMRI. 1. Using a dual task paradigm involving the Wisconsin Card Sort and shadowing (subjects hear then repeat words). We observed striking decreases in activation during the dual task condition and qualitative increases in cerebellar activation. These results suggest that cognitive overload phenomena may be associated with the disillusion of neural networks and consequent impairments in performance. 2. Using a continuous working memory task (""""""""n-back test""""""""), we found highly significant differences between schizophrenic patients and normal subjects in prefrontal activation as measured by fMRI. This task imposes continuous demands on the working memory system as it necessitates the maintenance of information over delays and resistance to interference. 3. We developed an episodic recognition memory task to be used in fMRI in order to examine a """"""""levels of processing"""""""" account of memory functioning in normal subjects and schizophrenics. In addition, we have worked out technical problems in verbal fluency tasks (semantic and phonologic) that involve both movement artifact and noise suppression. Thus in addition to working memory, we will be able to evaluate episodic memory and semantic memory.
Showing the most recent 10 out of 21 publications
