Functional Neuroimaging of Strategic Retrieval Processes

Washington University, Saint Louis MO

Investigators

Linked publications & trials

Abstract

[unreadable] DESCRIPTION (provided by applicant): Episodic remembering critically relies on the generation retrieval plans, the elaborative processing of retrieval probes, the resolution of interference, and the monitoring of the sufficiency of memory with respect to decision criteria. Although prefrontal cortex (PFC) is the favored candidate for these mechanisms, regional and hemispheric localization for these mechanisms is unclear. Using a component-process model we will: (1) Determine whether left PFC is critically involved in formulating episodic retrieval plans. Recent research contrasting context and item memory have consistently identified left PFC and indicated that activity is not dependent on success, suggesting that it is the intent to retrieve contextual information that is critical. Here we intend to separate cue/question and probe dependent activity and determine whether these regions respond to non-verbalizable probes during contextually based retrieval demands. (2) Conduct Decision Theory based manipulations of memory decision criteria. By manipulating the number, location, and quality of decision criteria we will isolate PFC regions critical for implementing decision rules to memory content. (3) Investigate hemispheric asymmetries during episodic retrieval. Recent evidence suggests hemispheric asymmetries in PFC (particularly dorsal and polar) with left regions associated with contextually specific source attribution, and homologous right PFC regions showing relative increases during judgments of item recency or frequency, which are potentially based on global familiarity assessment. By directly contrasting recency, frequency, and context retrieval for matched materials within subjects, we will test whether the hemispheres are involved in fundamentally different aspects of memory retrieval, advancing beyond earlier constructs such as "effort" or "difficulty". Neurological changes during healthy aging and neurological disorders (e.g., Alzheimer's Dementia, Mild Cognitive Impairment, Traumatic Brain Injury) severely impact memory performance. However, because the control or decision processes regulating memory expression are poorly understood, behavioral impairments could often result from damage to systems that represent or store memory evidence, systems responsible for imposing decisions upon that content, or some combination of the 2. Determining how PFC regions normally regulate the translation of memory content into decisions or actions is therefore critical in understanding the memory performance decline in the above populations. [unreadable] [unreadable] [unreadable]