Episodic memory for personally relevant information, evidence from aging, divided attention at retrieval and positron emission tomography

grantor: University of TorontoThree components of episodic memory are retrieval content, retrieval success, and retrieval experience. These components, as they relate to episodic memory for personally relevant information, were investigated in two behavioral experiments and in a positron emission tomography (PET) experiment; the PET study investigated the neural correlates of the three components with particular attention paid to changes in frontal activity. In each experiment retrieval content was investigated by comparing the retrieval of adjectives that were processed in one of four ways: in terms of the self, another person, social desirability, or phonological structure. Retrieval success was investigated by comparing recognition performance across the four conditions and/or between groups. Retrieval experience was investigated by using a "remember/know" (R/K) recognition procedure; R responses index retrieval that is accompanied by a "re-experiencing" of aspects of the encoding episode whereas K responses index retrieval based on a feeling of familiarity. The retrieval content results suggest that the retrieval of category specific information engages anterior cortical areas when the category is personally or socially relevant. The retrieval success results support previous suggestions of right frontal involvement. The retrieval experience results suggest that increases in frontal activity are more correlated with K responses than R responses. Additional frontal regions may be recruited for K responses to verify and monitor the output, and to engage additional strategic search processes to try to change K responses to R responses. R responses primarily engaged limbic regions and anatomically related structures that may deliver their output to right frontal regions or be "switched on" by them. The PET results converge with the results of the two behavioral studies. Relative to young adults under full attention, the R scores of old adults were smaller in only the self-reference and social desirability conditions, and young adults who divided their attention at retrieval performed similarly to old adults; previous studies have suggested that divided attention and aging affect frontal function. The present series of experiments shed light on the neuro-cognitive system that mediates the retrieval of self-referential information. The experiments revealed different components of episodic memory that contribute to the cognitive processes and patterns of neural activity associated with episodic memory for personally relevant information.Ph.D