The functional neuroanatomy of episodic memory.

Functional neuroimaging studies have revealed that effective encoding in episodic memory is associated with enhanced activity in left prefrontal cortex, whereas retrieval is accompanied by the enhancement of predominantly right-sided prefrontal activity. The extent of the contribution of prefrontal cortex to episodic memory, and the fact that the encoding and retrieval operations it supports are differentially lateralized, were unexpected on the basis of evidence from lesion studies. Such studies have highlighted the crucial role in episodic memory played by the hippocampus and related medial temporal lobe structures. Neuroimaging studies, however, have had only limited success in elucidating the role of the hippocampus in episodic memory. Refinements in experimental design and improved spatial resolution should promote rapid future progress with respect to this issue.