Deletion variant in the ADRA2B gene increases coupling between emotional responses at encoding and later retrieval of emotional memories R.M. Todd a,⇑ , D.J. Müller b , D.J. Palombo c,d , A. Robertson e , T. Eaton d , N. Freeman b , B. Levine c,d , A.K. Anderson f,⇑ a Department of Psychology, University of British Columbia, Canada b Department of Psychiatry, University of Toronto and Neurogenetics Section, Centre for Addiction and Mental Health, Canada c Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Canada d Department of Psychology, University of Toronto, Canada e Diagnostic Imaging and Research Institute, Hospital for Sick Children, Toronto, Canada f Department of Human Development, College of Human Ecology, Cornell University, United States article info Article history: Available online 19 October 2013 Keywords: Emotion Memory Genetic variation ADRA2B Norepinephrine Affective bias abstract A deletion variant of the ADRA2B gene that codes for the a2b adrenoceptor has been linked to greater sus- ceptibility to traumatic memory as well as attentional biases in perceptual encoding of negatively valen- ced stimuli. The goal of the present study was to examine whether emotional enhancements of memory associated with the ADRA2B deletion variant were predicted by encoding, as indexed by the subjectively perceived emotional salience (i.e., arousal) of events at the time of encoding. Genotyping was performed on 186 healthy young adults who rated positive, negative, and neutral scenes for level of emotional arou- sal and subsequently performed a surprise recognition memory task 1 week later. Experience of child- hood trauma was also measured, as well as additional genetic variations associated with emotional biases and episodic memory. Results showed that subjective arousal was linked to memory accuracy and confidence for ADRA2B deletion carriers but not for non-carriers. Our results suggest that carrying the ADRA2B deletion variant enhances the relationship between arousal at encoding and subsequent memory for moderately arousing events. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction There is evidence that emotionally salient events are typically remembered more vividly than everyday ones (Kensinger & Corkin, 2003; Sharot, Martorella, Delgado, & Phelps, 2007). Yet individuals differ in the degree to which emotional salience enhances memory (Hamann, Ely, Grafton, & Kilts, 1999; Todd, Palombo, Levine, & Anderson, 2011) as well as in their susceptibility to intrusive mem- ories associated with post-traumatic stress disorder (PTSD) (Yehu- da & LeDoux, 2007). Individual differences may also partly explain conflicting findings in the literature, with some studies reporting that memory is enhanced for emotionally arousing relative to neu- tral events [e.g., (Brown & Kulik, 1977; Ochsner, 2000)], and other studies failing to find such an effect (Sharot, Verfaellie, & Yonelinas, 2007). The modulation hypothesis (McGaugh, 2002) proposes that in- creased norepinephrine (NE) activity in the basolateral amygdala (BLA) elicited by an affectively salient event enhances encoding of the event. Such arousal related activity at encoding further inter- acts with the influence of NE on longer-term memory consolida- tion processes to enhance memory for salient events (Cahill & Alkire, 2003; Roozendaal & McGaugh, 2011). This hypothesis is supported by findings that in rats, administration of NE into the BLA both prior to and following encoding of an event is associated with enhanced memory (for review see Roozendaal et al. (2009) and Roozendaal and McGaugh (2011)). In humans, the influence of arousal on both encoding and post-encoding processes has been demonstrated by injecting epinephrine or exposing participants to emotionally arousing images prior or subsequent to encoding (Anderson, Wais, & Gabrieli, 2006; Cahill & Alkire, 2003; Cahill, Gorski, & Le, 2003; Cahill, Prins, Weber, & McGaugh, 1994; Schwarze, Bingel, & Sommer, 2012). We have recently shown that, in humans, enhanced arousal at encoding is associated with the experience of emotion enhanced perceptual vividness (EEV), which in turn predicts the vividness of later memory (Todd, Talmi, Sch- mitz, Susskind, & Anderson, 2012). 1074-7427/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.nlm.2013.10.008 ⇑ Corresponding authors. Address: Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, BC V6T 1Z4, Canada (R.M. Todd). Address: G77 Martha Van Rensselaer Hall, Department of Human Development, College of Human Ecology, Cornell University, Ithaca NY 14850, USA. (A.K. Anderson). E-mail address: becket.todd@psych.ubc.ca (R.M. Todd). Neurobiology of Learning and Memory 112 (2014) 222–229 Contents lists available at ScienceDirect Neurobiology of Learning and Memory journal homepage: www.elsevier.com/locate/ynlme