Direct comparison of episodic encoding and retrieval of words: An event-related fMRI study

Functional magnetic resonance imaging (fMRI) was used to compare directly e pisodic encoding and retrieval. During encoding, subjects studied visually presented words and reported via keypress whether each word represented a p leasant or unpleasant concept (intentional, deep encoding). During the retr ieval phase, subjects indicated (via keypress) whether visually presented w ords had previously been studied. No reliable differences were found during the recognition phase for words that had been previously studied and those that had not been studied. Areas preferentially active during encoding (re lative to retrieval) included left superior frontal cortex, medial frontal cortex, left superior temporal cortex, posterior cingulate, left parahippoc ampal gyrus, and left inferior frontal gyrus. Regions more active in retrie val than encoding included bilateral inferior parietal cortex, bilateral pr ecuneus, right frontal polar cortex, right dorsolateral prefrontal cortex, and right inferior frontal/insular cortex.