An Event-related Potential Of Encoding And Retrieval

Retrieval and encoding all are important phases of memory, but in the past, few experiments investigate the relationship between encoding and retrieval, especially in the domains of source memory and item memory. Moreover, few experiments compare ERPs of encoding with corresponding ERPs of retrieval, and recollection with familiarity.To probe into the relationship of encoding and retrieval, source memory and item memory, recollection and familiarity, we collected data with event-related potential(ERP), and used the stimulus of words. The experiment included two parts. Source memory: subjects were instructed to judge among the new words, the old words with ring background and the old words with pane background. Item memory: subjects were instructed to make old/new judgement.The results indicated that, in encoding phase, Dm effects were found both in source memory and in item memory, but had no difference in magnitude. Moreover, in source memory, Dm effects were found both in recollection and familiarity, and the time cource of Dm effect of recollection was earlier than that of familiarity.In retrieval phase, two old/new effects were found both in source memory and in item memory. First old/new was that ERP of correctly judged old words was mere positive than that of correctly judged new words. But old/new effect in source memory was bigger than that in item memory. In addition, there were old/new effects between recollection (Hit/Hit) and new, and familiarity (Hit/Miss) and new, and the former was bigger than the latter. Second old-new effect was that ERP of old words judged as old was more positive than that of old words judged as new. This effect in source memory was bigger than that in item memory. In addition, two old-new effects: recollection vs. "ncw"(i.e. miss), familiarity vs. "new"(i.e. miss) were found in source memory. And in retrieval phase, ERP of recollection was more positive than that of familiarity in source memory.To analyze exactly the relationship of retrieval and encoding, we compared Dm effect in encoding phase with second old-nev/ effect in retrieval phase. The results indicated that the neuralmechanisms of encoding and retrieval may be different. In item memory, the time course of Dm effect was earlier than that of corresponding old-new effect. In source memory, ERP of recollection was more positive than that of familiarity in retrieval phase. But in encoding phase, there was no significant difference; In retrieval phase, old-new effect of recollection was bigger than that of familiarity, but in encoding phase, there was no difference between their corresponding Dm effects. In addition, the time course of familiarity Dm effect was the same as that of second old-new effect, but more brain regions were activated with old-new effect; the time courses of Dm effects of recollection (Hit/Hit) and remember (Hit/Hit+Hit/Miss) both were earlier than their corresponding old-new effects, but more brain regions were activated with old-new effect. These results indicated that, just as the review of Endel Tulving in one talk, " the key process in memory is retrieval."...