Me, Myself, and fMRI: The Effects of Cortisol on Self-Referential Processing and Amygdala Activation Elana G. Brubaker, Allison L. Jahn, Heather C. Abercrombie, Richard J. Davidson Background The self-reference effect (SRE) is the phenomenon in which people remember adjectives better when the adjectives are thought of in reference to themselves versus someone else or when thinking about the word in general (Weiten et al., 2001). Essential to this phenomenon is the individual’s perception of the self, which is generally tied to the medial prefrontal cortex and the amygdala. These areas of the brain are also closely ingrained in the formation and recall of memories, allowing the brain to help control emotional behavior and the expression of negative emotion (Carlson, 2007). Increased activation of the amygdala has been found when individuals are involved in a self-referential task, although lateralized amygdala activation is often found. Studies have shown that the right side of the amygdala is more greatly activated when the individual is encoding negative words, while the left amygdala is more active when encoding positive words (Ramel et al., 2007). This increased activation throughout the amygdala may allow individuals to process self-referential words more quickly than other words, due to the strong emotionality of the those words. Watson et al. (2007) accredited the quicker response times to the self-positivity bias, meaning that people responded faster to positive words in order to maintain a positive self-image. Methods Participants completed 5 sessions. Screening session to ensure potential subjects are able to participate Simulation session to allow subjects to become accustomed to the task and the scanner fMRI scans during which the tasks take place. Each participant given hydrocortisone pill one day and placebo the other Memory session Phone Screen MRI Simulation Memory Test Screening Visit 15 mg Cortisol Placebo Counterbalanced 3.0 Tesla GE SIGNA Scanner Beginning approx. 4:30pm Valence x Drug Main effect of word valence Positive words were rated as being more self-referential than negative or neutral words Participants responded “yes” to positive words more often than negative or neutral words Conclusion Our hypothesis that participants would respond that more positive words were rated as self-referential than neutral or negative words was supported. Also, the hypothesis that participants would respond more quickly to negative words than to words of other valences was also supported, a finding that was paralleled by Watson et al. (2007), who found that emotionally charged words led participants to react more quickly in a self-referential task. In a follow-up analysis we examined the correlation between reaction time and brain activation. These data show significant correlations between activation of the right amygdala while processing negative words and the activation of the left amygdala while processing positive words. Hypotheses We hypothesize that participants would respond more quickly to negative than to neutral or positive words. Further, we hypothesize that participants will respond more quickly to words rated as self-referential. Finally, we hypothesized that participants would rate more positive words as self-referential than neutral or negative words. quiet + 2s 4-8s 2 runs; approx. 12 min lonely angry FMRI Stimuli Presentation Self-Referential Task Participants were shown 32 positive words, 32 negative words, and 24 neutral words Then they were asked to determine whether each word did or did not describe them Each word was shown for 2 seconds Fixation period between words, variable length Participants Thirty-nine participants were included in this analysis. Data used in this analysis are from a larger ongoing fMRI study that will include both control and depressed participants. Participants were between 18 and 49 years of age (mean = 25.44, SD = 6.88). This sample included 22 males and 17 females. Participants had to be in good physical health, right-handed, and non-smokers. Participation was voluntary, and participants were compensated $300 at the end of the study for their time. Amygdala Activation During Remembered Negative Words When Given a Placebo No hypotheses were made regarding amygdala activation, and therefore the following correlations are exploratory. Negative correlation between left amygdala activation and reaction time for positive words, r = -0.478, p < .01 Positive correlation between right amygdala activation and the number of times participants responded “yes” to negative words, r = 0.349, p = .046 Reaction Time x Response Faster reaction time for words rated as self-referent T = -2.073, p = .046 * Reaction Time x Valence Faster reaction time for negative words versus neutral words, t = -8.603, p < .01 Faster reaction time for negative words versus positive words, t = -4.811, p < .01 * References Carlson, N. R. 2007. Physiology of Behavior. Pearson Education, Inc, Boston. Ramel, W., Goldin, P. R., Eyler, L. T., Brown, G. G., Gotlib, I. H., McQuaid, J. R. 2007. Amygdala reactivity and mood-congruent memory in individuals at risk for depressive relapse. Biological Psychiatry. 61: 231-239. Watson, L. A., Dritschel, B., Obonsawin, M. C., Jentzsch, I. 2007. Seeing yourself in a positive light: Brain correlates of the self-positivity bias. Brain Research. 1152: 106-110. Weiten, W. 2001. Psychology Themes and Variations. Thomson Learning, Inc. Belmont.