Object priming and recognition memory: Dissociable effects in left frontal cortex at encoding

Functional magnetic resonance imaging (fMRI) studies have implicated the left prefrontal cortex in priming. We tested the hypothesis that object encoding activity in different prefrontal cortex regions selectively predicts subsequent object priming and recognition respectively. Participants were scanned whilst making semantic category judgements about novel object pictures. One week later priming and recognition of these objects were tested. Encoding that produced long-lasting priming in the absence of recognition memory was associated with increased activity in left inferior prefrontal (BA 47) and superior frontal (BA 8) cortices. In contrast, encoding that produced object recognition one week later activated the left middle frontal cortex (BA 9). This is consistent with other evidence indicating that object priming and recognition are independent kind of memory. Problems of measuring item-by-item recognition and priming together are discussed.