Encoding Stage Of Processing On The Prefrontal Cortex Of Old And New Effects Of Extraction Stage

Item memory and source memory are two important aspects of episodic memory, source memory is defined as the time, place and background information of the object we should remember. At present, fewer researchers distinct the intre-item and extra-item attributes of source memory explicitly. In this study, the three key response paradigm of study-test was adopted to investigate the impact of encoding precess to the prefrontal effect in the recollection.It is well established that source memory retrieval engages prefrontal cortex (PFC) more than simple item memory. In event-related potentials (ERPs), this is manifest in a late-onset difference over PFC between studied and unstudied items which can be immediately rejected. Although some sorts of attribute conjunctions are easier to remember than others, the role of source retrieval difficulty on prefrontal activity has received little attention. We examined memory for conjunctions of objects and backgrounds when the subjects told to make a judgment about the adaptability between the two, and when the subjects told to make a judgment about the size between the real object and the CRT monitor in the front of them. When the subjects do the size-judgment task, the accuracy of their source memory is low, however, the prefrontal activity is equally between these two conditions. The insensitivity of prefrontal ERPs to this perceptual manipulation of difficulty stands in contrast to their sensitivity to encoding task:deliberate voluntary effort to integrate objects and colors during encoding reduced prefrontal activity during retrieval, but perceptual organization of stimuli did not.17 subjects took part in the size-judgment and matching judgment tasks, the result indicated that there is no difference in reaction time and accuracy rate between the two tasks during the study phase, and the matching judgment task had a longer reaction time and a lower accuracy rate. During the test phase, the main effect between types of group was not significant, and the types and conditions or sites had no significant interaction. This showed that differences in task difficulty between the two groups does not affect the the prefrontal effect in the test phase, which proved that stimulus of any difficulty will all have a prefrontal old/new effect during recollection, however, different coding difficulty of extra-item material didn't have a significant impact on the prefrontal effect in the recollection phase.