The role of encoding strategy in subsequent recognition in schizophrenia
Aaron Bonner-Jackson, Kristin M. Haut, John G. Csernansky, Deanna M. Barch*
Research suggests that impairments in the ability to spontaneously apply effective encoding and/or retrieval strategies contribute to episodic memory deficits in schizophrenia. The goal of this study was to examine the effect of providing encoding strategies on brain activation during encoding and on subsequent recognition performance in individuals with schizophrenia. Participants with schizophrenia and control subjects underwent fMRI scans while performing encoding and recognition tasks of words and non-famous faces. During encoding, subjects made either semantic (deep encoding) or orthographic (shallow encoding) judgments for words and gender (deep encoding) judgments for faces. During recognition, subjects indicated whether given words or faces had been seen previously. Individuals with schizophrenia demonstrated better memory for words encoded deeply than shallowly and activated semantic processing regions (left BA 45/47) for deep as compared to shallow encoding tasks. Interestingly, the patients also demonstrated more deep encoding-related activity than controls in anterior left inferior prefrontal regions, as well as activation of homologous right BA 47, perhaps reflecting compensatory memory processes. When oriented towards appropriate strategies, individuals with schizophrenia showed left lateralized prefrontal activity for words and right lateralized prefrontal activity for faces. However, during recognition memory individuals with schizophrenia no longer showed left lateralized prefrontal activity for words, though controls did. When given advantageous strategies, individuals with schizophrenia show enhanced subsequent memory performance and engage task appropriate neural systems. However, when strategy is unconstrained, individuals with schizophrenia show abnormal patterns of brain activity and impaired task performance.
Supported by a Conte Feasibility Center for Neuroscience Research (MH071616-01)