An FMRI Study Of Item Memory And Source Memory

Objective Episodic memory is a kind of memory for events that occurred in a particular place at a particular time.Episodic memory contains information about the content of an experience(item),as well as its context(source).the former is item memory(familiarity);the latter is source memory (color vs shapes).In the last decade,a growing body of evidence has been amassed regarding the neural substrates associated with item memory; however, much less is known about the neural basis associated with source memory.with the use of functional magnetic resonance imaging(fMRI) and positron emission tomography (PET), item memory has been shown to consistently activate right prefrontal cortex, consistent with Tulving's hemispheric encoding/retrieval asymmetry model(HERA MODEL).Some researchers have argued for a dual-process model of source and item memory, namely the prefrontal regions subserve source memory and the hippocampal regions subserve item memory. Whereas others have argued for a single process model that holds that both frontal and hippocampal areas are more involved in source than in item memory retrieval.there are no quality difference between source memory and item memory,but difference in quantity. Though few in number,fMRI studies on item memory and source memory have produced very consistent results,which demonstrated that item memory was mainly associated with activity in the right prefrontal cortex and source memory was mainly associated with activity in the left prefrontal cortex.in addition,lots of behavioral differences between men and women have been documented across cognitive domains.A consistent finding is that men perform better on spatial tasks,whereas women outperform men on some verbal and memory tasks.by means of BOLD-fMRI, Shaywitz et al.reportedthat women tend to excel men in accomplishment of phonological tasks, women showed more bilateral frontal gyrus activation, whereas, men showed unilateral inferior frontal gyrus activation.The major purpose of this study was to investigate brain regions activated by item memory and source memory,and validated the feasibility of single-process and dual-process model, in addition,examined whether gender differences existed in item memory and source memory.Materials and Methods Sixteen neurologically intact right-handed native Chinese speakers with normal(or corrected) eyesight(eight male and eight female), aged between 22 and 26 years(with a mean age of 23.6 years).5O4 high-frequence Chinese double-character phrases were used.participants were scanned during six sessions ordered as study-test-study-test conditions.At study,subjects were presented with Chinese characters displayed either red or green,and depending on the color, performed one of pressing left or right mouse button task.The test phase consisted of a sequence of three 16-items blocks.For one block, subjects performed simple control tasks in sixteen old words(eight red and eight green) that had presented at study,the participants was to indicate with pressing left or right button when items was red or green. For another block, item memory were performed on a mixture of eight old and eight new items,the participants was asked to judge whether the items presented was seen or not seen.In the remaining block,consisting of 16-old-black items,the requirement was to judge whether each word that had presented at study was red or green.Results Both item memory and source memory attracted bilateral dorsolateral prefrontal cortex(BA6).relative to source memory,only item memory was associated with increased activity in right dorsolateral prefrontal cortex(BA46),right hippocampus and right superior parietal gyrus(BA7).Only source memory was associated with increased activity left middle prefrontal cortex(BA10) and left hippocampus. Relative to item memory,^eater activity was found in anterior cingulate cortex(BA32/24),left inferior...