A resting‐state fMRI study of obese females between pre‐ and postprandial states before and after bariatric surgery

Abstract

Past studies utilizing resting-state functional MRI (rsfMRI), have shown that obese humans exhibit altered activity in brain areas related to reward compared to normal-weight controls. However, to what extent bariatric surgery-induced weight loss alters resting-state brain activity in obese humans is less well-studied. Thus, we measured the fractional amplitude of low-frequency fluctuations from eyes-closed, rsfMRI in obese females (n = 11, mean age = 42 years, mean BMI = 41 kg/m 2 ) in both a pre-and postprandial state at two time points: four weeks before, and four weeks after bariatric surgery. Several brain areas showed altered resting-state activity following bariatric surgery, including the putamen, insula, cingulate, thalamus and frontal regions. Activity augmented by surgery was also dependent on prandial state. For example, in the fasted state, activity in the middle frontal and pre-and postcentral gyri was found to be decreased after surgery. In the sated state, activity within the insula was increased before, but not after surgery. Collectively, our results suggest that resting-state neural functions are rapidly affected following bariatric surgery and the associated weight loss and change in diet.

Resting‐State Brain Connectivity Predicts Weight Loss and Cognitive Control of Eating Behavior After Vertical Sleeve Gastrectomy

“…SN hyperconnectivity in individuals with obesity may underlie the overintegration of multisensory information and appetite in individuals with obesity (11), with previous studies reporting attenuation and normalization of FC in the SN 1 to 12 months following bariatric surgery (9,16). Our results are consistent with these findings and with task-based FC studies demonstrating altered FC in the SN and visual areas in lean individuals versus those with obesity during a food processing task (30).…”

“…The SN is linked to integration of high‐level sensory information with visceral, autonomic, and hedonic signals . Recent studies have investigated the effects of bariatric surgery on FC, with assessments of patients at 1 , 3 to 4 and 12 months post surgery. In a cross‐sectional study, individuals with severe obesity who did not undergo surgery demonstrated increased FC strength within the DMN compared with Roux‐en‐Y gastric bypass (RYGB) patients scanned at least 1 year after surgery .…”

“…The SN is linked to integration of high-level sensory information with visceral, autonomic, and hedonic signals (15). Recent studies have investigated the effects of bariatric surgery on FC, with assessments of patients at 1 (16,17), 3 to 4 (18,19) and 12 (9,20) months post surgery.…”

Bariatric surgery in obese patients reduced resting connectivity of brain regions involved with self‐referential processing

“…An association between lessened postoperative craving for high-caloric food and diminished activity within prefrontal region (dorsolateral prefrontal cortex-DLPFC) has also been observed 1 month post-surgery (Bruce et al, 2012;Ochner et al, 2012). Particularly, RS-fMRI studies have also revealed a partial reversal of hypothalamic dysfunction and altered brain activity (insula) following body mass index (BMI) reduction (Van de Sande-Lee et al, 2011; Wiemerslage et al, 2017). Bariatric surgery also decreased RSFC within the DMN comprising the anterior cingulate cortex (ACC), frontal superior gyrus, and orbitofrontal cortex (Frank et al, 2014) and RSFC between insula/left precuneus (Lepping et al, 2015).…”

Neuroimaging correlates of cognitive changes after bariatric surgery

“…Single-photon energy computed tomography brain perfusion has been used to demonstrate that obesity can be associated with reduced prefrontal cortex blood flow [17]; but the study did not assess longitudinal changes of blood flow from weight loss or correlate them with cognitive function. Studies of functional brain connectivity using blood oxygenation level dependent (BOLD) resting-state functional MRI (rsfMRI) have shown baseline deficits and longitudinal improvements in functional connectivity of brain regions after bariatric surgery [18][19][20], but similarly failed to assess longitudinal association of these changes with changes in cognitive function.…”