NETWORKS OF DOMAIN-SPECIFIC AND GENERAL REGIONS INVOLVED IN EPISODIC MEMORY FOR SPATIAL LOCATION AND OBJECT IDENTITY

Positron emission tomography (PET) was used to investigate human episo dic memory for spatial location and object identity. We measured regio nal cerebral bloodflow (rCBF) while subjects engaged in perceptual mat ching of the location or the identity of line drawings of objects. Per ceptual matching also involved incidental encoding of the presented in formation. Subsequently, rCBF was measured when subjects retrieved the location or the identity of these objects from memory. Using the mult ivariate partial least squares image analysis, we identified three pat terns of activity across the brain that allowed us to distinguish stru ctures that are differentially involved in processing spatial location and object identity from structures that are differentially involved in encoding and retrieval but operate across both domains. Domain-spec ificity was evident by increased rCBF during the processing of spatial location in the right middle occipital gyrus, supramarginal gyrus, an d-superior temporal sulcus, and by increased rCBF during the processin g of object identity in portions of bilateral lingual and fusiform gyr i. There was a nearly complete overlap between domain-specific dorsal and ventral extrastriate cortex activations during perceptual matching and memory retrieval. Evidence of domain-specificity was also found i n the prefrontal cortex and the left hippocampus, but the effect inter acted with encoding and retrieval. Domain-general structures included bilateral superior temporal cortex regions, which were preferentially activated during encoding, and portions of bilateral middle and inferi or frontal gyri, which were preferentially activated during retrieval. Together, our data suggest that encoding and retrieval in episodic me mory depend on the interplay between domain-specific structures, most of which are involved in memory as well as perception, and domain-gene ral structures, some of which operate more at encoding and others more at retrieval. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.