Encoding and Retrieval Processes in Declarative Memory

Project summary

Using a novel behavioral science strategy probing the functional architecture of long-term memory and its disruption in the early course of schizophrenia. This project aims:

  1. To evaluate functional dissociations between episodic and familiarity-based retrieval and between retrieval and encoding processes in long-term memory in healthy subjects; and
  2. To evaluate the possible differential relevance of episodic versus familiarity-based retrieval and of encoding versus retrieval processes in long-term memory in relation to symptom onset and functional outcome in schizophrenia.

This is the first study to test whether behavioral and physiologic deficits in particular aspects of long-term memory precede and predict the onset of psychotic symptoms and whether these changes are differentially related to short-term changes in social and work outcome and to variability in the long-term course of functional outcome in schizophrenia. If behavioral and/or physiologic deficits in long-term memory functioning can improve the prediction of conversion to schizophrenia above that associated with prodromal behavioral features, this information could lead to better theoretical specification of the mechanisms underlying psychosis onset and eventually to improved preventive intervention strategies.

Investigators
Primary Investigator: 
Tyrone Cannon
Co-Investigators: 
Russell Poldrack
Co-Investigators: 
Mark Cohen
Other Investigators: 
Theo van Erp
Findings
Publications and documents produced by the team on this project
Summary: 

At the inception of the Memory Project, questions remained regarding the development, nature (e.g., encoding, retrieval), and neural underpinnings of the declarative memory deficit in schizophrenia. Based on neuropsychological studies, there was a general consensus that neurocognitive deficits do not progress over time after illness onset, but little was known with regard to putative deficits prior to the onset of illness. Our initial studies focused on clinical and neuropsychogocal measures in the prodrome and their continuity with first-episode schizophrenia (Niendam et al. 2006; Willhite et al. 2008).

We also started to examine similar questions in the domain of working memory (Karlsgodt et al. 2008; Karlsgodt et al. submitted). Within the Center, we were able to translate the basic science remember-know paradigm to evaluate the development, nature (e.g., encoding, retrieval), and neural underpinnings of the declarative memory deficit in schizophrenia.

We published a study validating the paradigm behaviorally in a chronic schizophrenia sample, and are the first to interpret the schizophrenia memory deficit based on the two most prominent basic science memory models to date (Van Erp et al. 2008).

The Center also allowed us to evaluate at-risk for psychosis (prodromal) and first-episode schizophrenia samples on this paradigm with fMRI. Collectively, these studies reveal a progressive deficit in recollection across the phases of illness. fMRI data indicate that both the first-episode and prodromal samples show aberrant neural activation in the declarative memory network during encoding and recognition (Van Erp et al. submitted; Van Erp et al. submitted).

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