Test‐retest reliability and postprandial time course of the neural responses to visual food stimuli

Abstract

The brain's reward system influences ingestive behavior and subsequently obesity risk. Functional magnetic resonance imaging (fMRI) is a common method for investigating brain reward function. We sought to assess the test‐retest reliability and postprandial time course of neural responses to visual food cues using fMRI. A priori brain regions of interest included bilateral insula, amygdala, orbitofrontal cortex, caudate, and putamen. Fasting‐state fMRI and appetite assessments were completed by 29 overweight or obese women (n=17) and men (n=12) on 2 days for test‐retest reliability analyses determined by intraclass correlation coefficient. A subset of 3 women and 4 men completed postprandial fMRI and appetite assessments 0, 90, 180, and 270 min after consuming a 300 kcal meal to document the postprandial time course of responses. Mean fasting‐state neural responses on Day 1 and Day 2 were not different in 8 of 10 regions of interest. However, test‐retest reliabilities of neural responses were mostly poor or unreliable. Only the left orbitofrontal cortex response demonstrated fair test‐retest reliability. Furthermore, neural responses to visual food stimuli were largely unaffected by meal consumption. In conclusion, fMRI‐measured responses to visual food cues in overweight and obese adults show relatively good group‐level reproducibility but considerable within‐subject variability and are insensitive to meal consumption.Support or Funding InformationAmerican Egg Board, NIH UL1 TR001108, USDA‐NIFA 2011‐38420‐20038, Purdue University Ingestive Behavior Research Center