FUNCTIONAL NETWORK ARCHITECTURE IN OBESITY: COMPARISON OF TASK-EVOKED AND RESTING STATE CONNECTIVITY

Functional alterations of the neural networks that support reward valuation and reward-driven decision making may be related to obesity. In support of this hypothesis, obesity is associated with differences in task-evoked and intrinsic functional connectivity. However, few studies have used a hypothesis-driven multimodal approach to compare obesity-related differences in functional network organization evoked by high calorie food cues and in the absence of externally-guided information processing demands. The sample included 122 adults (78% female; age M = 44.43, SD = 8.67) with body mass index (BMI) in the overweight or obese range (BMI M = 31.28, SD = 3.92) assessed prior to a behavioral weight loss intervention. Participants completed a functional MRI scan that included a resting period followed by a visual food cue task in which participants viewed alternating blocks of high and low-calorie foods and neutral non-food items. A seed-based approach was used, with seeds being located in regions including the orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC). Whole-brain functional connectivity analyses were conducted to examine seed-to-voxel signal covariation during the presentation of high calorie food and at rest. For all seeds selected for analysis, obesity was associated with stronger functional connectivity during the presentation of high calorie food, but weaker functional connectivity at rest. While regions located in the default mode network (e.g., mPFC, posterior cingulate cortex) exhibited BMI-dependent modulation of signal coherence in the presence of palatable food cues, regions involved in reward processing (e.g., basal ganglia) exhibited BMI-dependent modulation of signal coherence at rest. These data provide evidence that obesity predicts stronger functional connectivity between regions involved in reward valuation, self-directed thinking, memory, and emotion processing during the presentation of high calorie food cues, but weaker intrinsic functional connectivity in reward processing regions. These dissociable patterns of functional network organization are suggestive of separate mechanisms potentially contributing to variation in functioning in distinct cognitive, psychological, or behavioral domains. This may have implications for understanding individual differences in obesity