Source memory is defined as memory for not only the core aspect of some event, but additional contextual detail about that core aspect, or item. Source memory tasks are marked by their engagement of prefrontal cortex in addition to the brain circuits required by other episodic memory tasks. The dissertation examines the relationships among source memory accuracy, concurrent brain activity, and general cognitive principles derived from the study of episodic memory more generally. Electrical measures of brain activity (event-related potentials, ERPs) were recorded while manipulating factors hypothesized to improve or worsen source memory accuracy.The first experiment manipulated the task assigned during the encoding phase and its match to the retrieval demands of remembering objects (depicted in drawings) and their colors. As predicted by the principle of transfer-appropriate processing, source accuracy was higher when the encoding task fostered integration of the item (object) and source (color) attributes. Prefrontal activity during the retrieval phase was greatly reduced when retrieval could benefit from transfer-appropriate processing.In associative memory tasks, poor memory performance is observed when the to-be-retained stimuli share elements with other studied stimuli, as in a variety of interference paradigms. The second experiment thus examined the impact of feature overlap on source recognition by varying the quantitative mapping between the shape and color of an object depicted in a drawing. The results showed two frontal processes supporting source retrieval: an early differentiation between stimuli identical to those encoded and those that switch colors from study to test, and a later effect reflecting prolonged memory search that was truncated by reinstating unique object-color pairings at test.The final experiment compared conjunctions of "intra-item" versus "extra-item" features, by placing the features within a single visual object or distributing them across two visual objects. Source accuracy was worse when shape and color were spatially separated, but prefrontal activity did not vary. The insensitivity of prefrontal ERPs to this perceptual manipulation of difficulty stands in contrast to their sensitivity to encoding task. Individual variability in parietal ERPs was strongly correlated with source accuracy, and likely reflects a contribution of visual working memory to long-term memory.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/193740 |
| Date | January 2007 |
| Creators | Kuo, Trudy Yang |
| Contributors | Van Petten, Cyma, Van Petten, Cyma, Glisky, Elizabeth, Ryan, Lee, Rapcsak, Steve |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Electronic Dissertation |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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