IS PREFRONTAL CORTEX INVOLVED IN CUED-RECALL - A NEUROPSYCHOLOGICAL TEST OF PET FINDINGS

Positron emission tomography (PET) experiments have detected blood flo w activations in right anterior prefrontal cortex during performance o f a word stem cued recall task [3, 38]. Based on findings from a varie ty of PET studies, the ''hemispheric encoding/retrieval asymmetry mode l'' [44] was proposed to explain the role of the frontal lobes in epis odic memory. This model asserts that left prefrontal cortex is prefere ntially involved in the encoding of new information into episodic memo ry, whereas right prefrontal cortex is more involved in episodic memor y retrieval. As a neuropsychological test of this hypothesis, a group of frontal patients with lesions in areas 6, 8, 9, 10, 44, 45 and/or 4 6 (11 left, five right) were run on word stem cued recall under two se mantic study conditions. As a group, these patients were not significa ntly impaired in cued recall. In the first but not the second experime nt, left frontal patients recalled fewer words than controls. Right fr ontal patients were not impaired on either list. Right prefrontal cort ex could be activated by several strategic aspects of the cued recall paradigm that were minimized in the present experiment. Brain reorgani zation in the lesioned patients could also account for their intact pe rformance. The regions of prefrontal cortex activated in PET studies o f young controls are not necessary for patients to perform the task. C opyright (C) 1996 Elsevier Science Ltd