Contents lists available at ScienceDirect Physiology & Behavior journal homepage: www.elsevier.com/locate/physbeh The impact of elevated body mass on brain responses during appetitive prediction error in postpartum women Grace E. Shearrer a , Tonja R. Nansel b , Leah M. Lipsky b , Jennifer R. Sadler a , Kyle S. Burger a,c, ⁎ a Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America b Social and Behavioral Sciences Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health & Human Development, Bethesda, MD, United States of America c Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America ARTICLE INFO Keywords: Functional MRI Reward, obesity Prediction error ABSTRACT Repeated exposure to highly palatable foods and elevated weight promote: 1) insensitivity to punishment in striatal regions and, 2) increased willingness to work for food. We hypothesized that BMI would be positively associated with negative prediction error BOLD response in the occipital cortex. Additionally, we postulated that food reinforcement value would be negatively associated with negative prediction error BOLD response in the orbital frontal cortex and amygdala. Postpartum women (n = 47; BMI = 25.5 ± 5.1) were ‘trained’ to associate specific cues paired to either a highly palatable milkshake or a sub-palatable milkshake. We then violated these cue-taste pairings in 40% of the trials by showing a palatable cue followed by the sub-palatable taste (negative prediction error). Contrary to our hypotheses, during negative prediction error (mismatched cue-taste) versus matched palatable cue-taste, women showed increased BOLD response in the central operculum (pFWE = 0.002; k = 1680; MNI: -57, -7,14) and postcentral gyrus (pFWE = 0.006, k = 1219; MNI: 62, -8,18). When com- paring the matched sub-palatable cue-taste to the negative prediction error trials, BOLD response increased in the postcentral gyrus (r = -0.60, pFWE = 0.008), putamen (r = -0.55, pFWE = 0.02), and insula (r = -0.50, pFWE = 0.01). Similarly, viewing the palatable cue vs sub-palatable cue was related to BOLD response in the putamen (pFWE = 0.025, k = 53; MNI: -20, 6, -8) and the insula (pFWE = 0.04, k = 19, MNI:38, -12, -6). Neither BMI at 6-month postpartum nor food reinforcement value was related to BOLD response. The insula and putamen appear to encode for visual food cue processing, and the gustatory and somatosensory cortices appear to encode negative prediction errors. Differential response in the somatosensory cortex to the matched cue-taste pairs to negative prediction error may indicate that a palatable cue may dull aversive qualities in the stimulus. 1. Introduction Increased energy needs and weight gain characterize pregnancy [1]. However, in the last two decades pregnancy weight retention has be- come a risk factor for future development of obesity in both the mother and child [2–7]. Despite substantial evidence of the negative con- sequences of postpartum weight retention, interventions have been generally unsuccessful [8,9]. Desire to consume palatable foods is a noted barrier to weight loss in women [10] and overconsumption of palatable foods has been linked overweight and obese status [11]. Understanding the desire and motivation to over consume palatable foods may inform the development of more effective intervention strategies. Intake of palatable food, a hedonic reward, is a multidimensional behavior comprised of learning, incentive motivation, and pleasure [12]. While the expected value of a stimulus [13], salience of both a cue and a stimulus [13] are important components of learning; Mirenowicz and Schultz’ prediction error theory posits that the brain learns about rewarding stimuli through coding unexpected outcomes as pleasurable or unpleasant if they are better or worse than the expected respectively [14,15]. As a simple example, consider a tray of cookies that appear to be chocolate chip. However, upon biting into a cookie one realizes that it is in fact an oatmeal raisin cookie, a flavor the individual does not enjoy. As the person dislikes oatmeal raisin cookies, but was expecting a highly pleasant chocolate chip cookie, she/he experienced negative prediction error; characterized as an anticipated pleasant outcome that, when experience, is worse than expected. As a function of this re- inforcing learning experience, the person now has learned that this tray of cookies contains different cookies and cookie selection requires closer attention. As such, prediction errors act to update the brain with https://doi.org/10.1016/j.physbeh.2019.04.009 Received 30 November 2018; Received in revised form 11 April 2019; Accepted 11 April 2019 ⁎ Corresponding author at: 2212 McGravran-Greenberg Hall, CB 7461, Chapel Hill, NC 27599, United States of America E-mail address: kyle_burger@unc.edu (K.S. Burger). Physiology & Behavior 206 (2019) 243–251 Available online 13 April 2019 0031-9384/ © 2019 Published by Elsevier Inc. T