Episodic Long-Term Memory

Higher order cognition depends on the ability to form and retrieve lasting memories for events (i.e., long-term memory; LTM). Individuals with schizophrenia have severely impaired LTM, which in turn compromises their daily living skills. Research on the neural substrates of memory dysfunction in schizophrenia can provide a foundation for new approaches to diagnosis and rehabilitation. The prefrontal cortex (PFC) is thought to play a critical role in the implementation of working memory (WM) control processes that promote successful LTM encoding and retrieval. Our prediction is that different regions in prefrontal cortex implement different types of control processes, and that these processes are differentially affected in schizophrenia. We hypothesize that the ventrolateral PFC (VLPFC) is critical for attending to relevant items ("item-specific" WM) during memory encoding, whereas the dorsolateral PFC (DLPFC) is critical for building relationships between these items ("relational" WM). We propose that it is the latter mechanism that is disproportionately impaired in schizophrenia.

This translational functional magnetic resonance imaging research is being directed by Dr. J. Daniel Ragland at the UC Davis Imaging Research Center, in collaboration with basic cognitive neuroscience investigators at the UC Davis Center for Neuroscience (Dr. Charan Ranganath), the UC Davis Center for Mind and Brain (Dr. Simona Getty), the UC Davis M.I.N.D. Institute (Dr. Marjorie Solomon) and the Department of Psychology at UC Berkeley (Dr. Silvia Bunge). Current experiments are investigating relational versus item-specific encoding effects on subsequent LTM, effects of semantic strength and encoding instructions on false memory formation, and characterization of formal thought disorder in individuals with autism versus early psychosis.