The goal of the proposed research is to use functional magnetic resonance imaging (fMRI) to test two primary hypotheses about the nature of memory impairments in schizophrenia. The first is that impaired episodic memory in schizophrenia is related to dysfunctional semantic processing, reflected in failure to activate left inferior frontal gyrus (LIFG) during word encoding and recognition. The second hypothesis is that this LIFG dysfunction is primarily due to patients' impaired controlled processing of semantic information, rather than degradation of their semantic memory knowledge or automatic associative processes. The first hypothesis will be tested in experiments 1 & 2. Experiment one will employ the Penn Word Recognition Test (PWRT) which will allow us to replicate previous Positron Emission Tomography findings that impaired episodic memory is related to LIFG dysfunction during word encoding and retrieval. Experiment 2 will employ a shallow/deep word encoding and recognition paradigm that will permit us to test the role of self-generated organizational strategies in the semantic processing difficulties and related LIFG dysfunction in schizophrenia. The second primary hypothesis will be tested in the final two experiments. Experiment 3 will employ a cued semantic verbal fluency paradigm that will allow us to investigate the effect of reducing controlled processing demands on verbal fluency and LIFG function. The final experiment will use an uncued verbal fluency design that will permit a trial-by-trial examination of the effect of controlled versus automatic processing on LIFG function. This series of studies promises to uncover fundamental mechanisms of impaired semantic processing and related episodic memory and LIFG deficits in schizophrenia. Establishing this mechanism will lay the groundwork for future imaging studies and can help provide a rationale for developing cognitive interventions designed to remediate semantic processing and verbal memory deficits in schizophrenia in order to improve functional outcome.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH062103-02
Application #
6621559
Study Section
Special Emphasis Panel (ZRG1-BBBP-4 (01))
Project Start
2001-12-01
Project End
2005-11-30
Budget Start
2002-12-01
Budget End
2003-11-30
Support Year
2
Fiscal Year
2003
Total Cost
$198,125
Indirect Cost
Name
University of Pennsylvania
Department
Psychiatry
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Dickinson, Dwight; Ragland, J Daniel; Gold, James M et al. (2008) General and specific cognitive deficits in schizophrenia: Goliath defeats David? Biol Psychiatry 64:823-7
Ragland, J D; Moelter, S T; Bhati, M T et al. (2008) Effect of retrieval effort and switching demand on fMRI activation during semantic word generation in schizophrenia. Schizophr Res 99:312-23
Wolf, Daniel H; Gur, Ruben C; Valdez, Jeffrey N et al. (2007) Alterations of fronto-temporal connectivity during word encoding in schizophrenia. Psychiatry Res 154:221-32
Ragland, J Daniel; Valdez, Jeffrey N; Loughead, James et al. (2006) Functional magnetic resonance imaging of internal source monitoring in schizophrenia: recognition with and without recollection. Schizophr Res 87:160-71
Ragland, J Daniel; McCarthy, Erin; Bilker, Warren B et al. (2006) Levels-of-processing effect on internal source monitoring in schizophrenia. Psychol Med 36:641-8
Dickinson, Dwight; Ragland, J Daniel; Calkins, Monica E et al. (2006) A comparison of cognitive structure in schizophrenia patients and healthy controls using confirmatory factor analysis. Schizophr Res 85:20-9
Calkins, Monica E; Gur, Ruben C; Ragland, J Daniel et al. (2005) Face recognition memory deficits and visual object memory performance in patients with schizophrenia and their relatives. Am J Psychiatry 162:1963-6
Moelter, Stephen T; Hill, S Kristian; Hughett, Paul et al. (2005) Organization of semantic category exemplars in schizophrenia. Schizophr Res 78:209-17
Ragland, J Daniel; Gur, Ruben C; Valdez, Jeffrey N et al. (2005) Levels-of-processing effect on frontotemporal function in schizophrenia during word encoding and recognition. Am J Psychiatry 162:1840-8
Ragland, J Daniel; Gur, Ruben C; Valdez, Jeffrey et al. (2004) Event-related fMRI of frontotemporal activity during word encoding and recognition in schizophrenia. Am J Psychiatry 161:1004-15

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