Recalling word lists reveals "cognitive dysmetria" in schizophrenia: A positron emission tomography study

Objective: This study explored the neural circuitry used during recall of u nstructured verbal material in schizophrenic patients and healthy volunteer subjects. Method: The subjects were 13 healthy volunteers and 14 schizophr enic patients. All patients were free of medication, and all subjects were right-handed. Two experimental cognitive conditions were used: recall of no vel and practiced word lists (two 15-item lists from the Rey Auditory Verba l Learning Test). Both active recall tasks were compared with an eyes-close d resting baseline condition. A nonparametric randomization test was used t o determine within- and between-group differences in regional cerebral bloo d flow. Results: Performance on both the practiced and novel memory tasks w as nonsignificantly different in the patients and control subjects. During the novel memory task, the patients showed decreased flow in the right ante rior cingulate, right thalamus, and bilateral cerebellum (left greater than right) relative to the control subjects. When recalling the practiced word lists, the patients showed decreased flow in the left dorsolateral prefron tal cortex, bilateral medial frontal cortex, left supplementary motor area, left thalamus, left cerebellar regions, anterior vermis, and right cuneus. Conclusions: Patients with schizophrenia fail to activate cortical-ce rebe l lar-thalamic-cortical circuitry during recall of both well-learned and no vel word lists.