Neurophysiological correlates of emotional directed-forgetting in persons with Schizophrenia: An event-related brain potential study

Abstract

Background: Recent research has shown that patients with schizophrenia (SCZ) exhibit reduced directed forgetting (DF) for negative words, suggesting impaired ability to instantiate goal-directed inhibition in order to suppress a competing, emotion-driven responses (i.e., emotional memory enhancement). However, disrupted inhibition is not the only possiblemechanismbywhich patients couldmanifest reduced emotional DF. Therefore, the primary objective of the current study was to use event-related brain potential (ERP) recordings to investigate alternative hypotheses. Methods: ERPs were recorded while patients and controls completed an item-method DF paradigm using negative and neutral words. The N2 indexed goal-directed inhibition of to-be-forgotten items. The late positive potential (LPP) indexed emotional memory enhancement for negative study items. The P300 indexed selective rehearsal of to-be-remembered items. Results: The SCZ group exhibited a reduced DF effect overall, but this was not modulated by emotion. N2 amplitude at anterior siteswas larger for forget versus remember cues in the control group only, but this effect was not modulated by emotion. LPP amplitude was greater for negative versus neutral words in both groups, independent of region. P300 amplitude at posterior sites was greater for remember versus forget cues in the control group only. Discussion: These data suggest that reduced DF in SCZ may be due, in part, to both diminished goal-directed inhibition of to-be-forgotten items and reduced selective rehearsal of to-be-remembered items. However, these data do not support the hypothesis that goal-directed, inhibitory processes are disrupted by competing, emotion-driven processes in SCZ. Patients' ERP data also suggested that they did not exhibit disproportionately heightened encoding of emotional stimuli, nor did they have deficient selective rehearsal of to-beremembered emotional items. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Schizophrenia (SCZ) is characterized by abnormalities in both emotional and cognitive processing. However, the interactive contribution of these domains to SCZ psychopathology has not been welldelineated. To date, investigations of emotion-cognition interactions in SCZ have primarily focused on the effects of extraneous emotional distraction on primary cognitive processing. This literature has yielded inconsistent results, with behavioral and neuroimaging research suggesting both increased vulnerability (e.g., Bentall and Kaney, 1989; Dichter et al., 2010; Mohanty et al., 2005; Park et al., 2008; Strauss et al., 2008) and normal susceptibility to emotional interference (Anticevic et al., 2011, 2012; Demily et al., 2010; Diaz et al., 2011; Gopin et al., 2011). These apparently discrepant findings may stem fromvariability in methodology and sample characteristics across studies. They may also result from the fact that previous studies have failed to employ tasks that maximize the antagonistic relationship between cognitive and emotional determinants of behavior. Such antagonism frequently typifies cognition-emotion interactions in real-world settings (e.g., Metcalfe and Mischel, 1999; Bickel et al., 2007) andmay potentiate the likelihood that one will impact the other (Anticevic et al., 2012). That is, patients with SCZ may have difficulty prioritizing cognitive or contextual response cues as determinants of goal-directed behavior in the face of countermanding emotional cues that impel an alternative response. International Journal of Psychophysiology 98 (2015) 612–623 ☆ Author note: The authors would like to thank Iulia Patriciu, Katie Herdman, Carolyn Roy, and RoshiWagley for their contributions toward participant recruitment, data collection, and data management. ⁎ Corresponding author at: Department of Psychiatry and Behavioural Neuroscience, McMaster University, 100West 5th Street, Hamilton, ON L8N 3K7, Canada. Tel.: +1 905 522 1155x36239. E-mail address: bruce.christensen@mcmaster.ca (B.K. Christensen). http://dx.doi.org/10.1016/j.ijpsycho.2015.01.006 0167-8760/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect International Journal of Psychophysiology journal homepage: www.elsevier.com/locate/ijpsycho