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 pre-frontal cortex and the retrosplenial area, whereas retrieval was associated with activity in right prefrontal cortex and the precu-neus. 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.