Effect of Abuse History on Pain Reports and Brain Responses to Aversive Visceral Stimulation: An fMRI Study

Abuse history is common in irritable bowel syndrome (IBS) and is associated with greater pain reporting, psychologic distress, and poorer health outcome. These effects may be mediated by enhanced responses to aversive visceral stimuli. We investigated the effects of IBS and abuse history on pain reporting and brain activation in response to rectal distentions. Ten female patients with IBS and 10 controls were included. Half of patients in each group reported a history of abuse. Brain functional magnetic resonance imaging (fMRI) images and pain ratings were obtained during rectal distentions. Statistical parametric mapping identified activation in subregions of the dorsal cingulate cortex and covariation with rated pain. (1) Distention-elicited pain correlated with anxiety and activation of the posterior (PCC) and middle (MCC) dorsal cingulate subregions. (2) Subjects with a history of abuse showed greater activation in the left MCC ( = .022; t = 5.61) and PCC ( = .033; t = 5.00) than subjects without abuse. (3) Those with IBS and abuse reported greater pain than all others ( = .004), had more activity in the left MCC ( = .021; t = 5.29) and PCC ( = .049; t = 4.81), and had less activity in the left supragenual anterior cingulate (sACC) ( = .01; t = 4.86). Pain ratings during rectal distention are associated with activation of dorsal cingulate regions implicated in homeostatic afferent processing, and prior abuse enhances this activation. Patients with IBS and abuse report more pain, greater MCC/PCC activation, and reduced activity of a region implicated in pain inhibition and arousal (sACC). These findings suggest a possible explanation for the clinical observation of greater pain reporting and poorer outcome in IBS patients with a history of abuse

Impact of mindfulness-based stress reduction training on intrinsic brain connectivity

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Influence of Sucrose Ingestion on Brainstem and Hypothalamic Intrinsic Oscillations in Lean and Obese Women

Background & aimsThe study of intrinsic fluctuations in the blood oxygen level-dependent signal of functional magnetic resonance imaging can provide insight into the effect of physiologic states on brain processes. In an effort to better understand the brain-gut communication induced by the absorption and metabolism of nutrients in healthy lean and obese individuals, we investigated whether ingestion of nutritive and non-nutritive sweetened beverages differentially engages the hypothalamus and brainstem vagal pathways in lean and obese women.MethodsIn a 2-day, double-blind crossover study, 11 lean and 11 obese healthy women underwent functional magnetic resonance imaging scans after ingestion of 2 beverages of different sucrose content, but identical sweetness. During scans, subjects rested with eyes closed.ResultsBlood oxygen level-dependent fluctuations demonstrated significantly greater power in the highest frequency band (slow-3: 0.073-0.198 Hz) after ingestion of high-sucrose compared with low-sucrose beverages in the nucleus tractus solitarius for both groups. Obese women had greater connectivity between the right lateral hypothalamus and a reward-related brain region and weaker connectivity with homeostasis and gustatory-related brain regions than lean women.ConclusionsIn a functional magnetic resonance imaging study, we observed sucrose-related changes in oscillatory dynamics of blood oxygen level-dependent fluctuations in brainstem and hypothalamus in lean and obese women. The observed frequency changes are consistent with a rapid vagally mediated mechanism due to nutrient absorption, rather than sweet taste receptor activation. These findings provide support for altered interaction between homeostatic and reward networks in obese individuals