Memory template comparison processes in anhedonia and dysthymia

Authors


  • The first author undertook this research in partial fulfillment of the requirements for the Master of Arts degree at the University of Illinois under the supervision of the second author. This research was supported in part by NIMH grant MH39628 to the second author and by grants from the Research Board and the Department of Psychology of the University of Illinois.

  • We gratefully acknowledge consultation with Michael Coles, William J. Gehring, Risto Näätänen, Walter Ritter, and Clifford Saron and assistance from Lori Ebert, Mindy Mechanic, Mark Musselman, Judy Pouk, and Cindy Yee.

Abstract

Anhedonic subjects, potentially at risk for psychopathology because of a deficient ability to experience pleasure, have demonstrated a large N200 component in the event-related brain potential (ERP). The present experiment attempted to determine the psychological significance of this finding in light of Näätänen's (1990) distinction between N2a and N2b subcomponents. Anhedonics were contrasted with controls and dysthymics, an at-risk group reporting depression. Across groups, N2a was larger when a tone mismatched a longer run of preceding identical tones. Thus, an involuntary mismatch process appears to be intact in both at-risk groups. However, the three groups produced distinct N2bs as a function of stimulus sequence. The N2b finding for anhedonics is consistent with Knight's (1984, 1992) model of early stimulus processing deficits in schizophrenia.

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