Conjunction analysis of cortical activations common to encoding and retrieval.

The notion of overlap between encoding and retrieval processes is central in cognitive theories of episodic memory, but to date most functional neuroimaging studies have emphasized differences between these processes. In the present study, overlap between encoding and retrieval processes was investigated by analyzing data from a positron emission tomography (PET) study of encoding and retrieval of different kinds of event information. Using a conjunction analysis, we specifically aimed at identifying overlap in activation patterns for encoding and retrieval of three classes of event information: item, temporal, and spatial. It was found that both encoding and retrieval of spatial information activated posterior parietal areas bilaterally. In addition, item encoding and retrieval were associated with increased activity in the right temporal pole, and temporal encoding and retrieval with left inferior frontal and left inferior temporal regions. These findings suggest that when specific episodic information is retrieved from memory, regions involved in encoding of the same information are engaged.