BRAIN-REGIONS ASSOCIATED WITH ACQUISITION AND RETRIEVAL OF VERBAL EPISODIC MEMORY

IT is widely held that conscious recall of past experiences involves a specific system-episodic memory1. Patients with amnesia have gross impairments of episodic memory while other kinds of memory remain intact2,3, suggesting that a separable brain system underlies episodic memory. We have used positron emission tomography (PET) to identify components of this system in normal volunteers. A dual-task interference paradigm4 was used to isolate brain areas associated with acquisition, and a cueing paradigm5 to isolate the areas concerned with retrieval from verbal episodic memory. Acquisition was associated with activity in the left prefrontal cortex and the retrosplenial area, whereas retrieval was associated with activity in right prefrontal cortex and the precuneus. Our results provide clear evidence that episodic memory involves a network of specific prefrontal and posterior structures6,7 which can be fractionated into different component processes.