Su1962 IBS Patients Show Altered Behavioral and Functional Brain Responses During an Orienting Attention Task

Abstract

Background. Converging evidence suggests that increased attention to afferent signals from the gut plays an important role in the increased perceptual response to visceral stimuli reported in irritable bowel syndrome (IBS). We hypothesize that prefrontal circuitry controlling attention to threat-related stimuli is less efficient in IBS patients compared to healthy controls (HCs). Aims. To quantify and compare the efficiency of cognitive control regions underlying selective attention to threat-related stimuli between IBS patients and HCs, using a GI symptom unrelated paradigm. Methods. We measured brain response (Siemens 3 Tesla Trio MRI scanner) in 32 females (16 IBS patients, 16 HCs) during administration of the house face matching task, a cognitive task developed and validated to test selective attention to threatening stimuli as well as index processing of task-irrelevant threat stimuli. Subjects were presented with pictures of pairs of houses and faces (fearful or neutral) arranged in a vertical or horizontal orientation around a central fixation cross. During the task subjects were asked to match either houses or faces.. SPM8 was employed to preprocess and analyze the imaging data using the general linear model and a region of interest analysis examining cognitive control and emotional arousal regions. Results were considered significant at p<.05, corrected using family wise error. Results. No significant group differences were observed for reaction time or accuracy on the house face matching task. However, when examining brain responses to viewing attended fearful versus attended neutral faces (AF-AN), IBS patients exhibited significantly greater brain activation compared with HCs in prefrontal control regions [dorso and ventrolateral prefrontal cortex (PFC), medial PFC] as well as in dorsal anterior insula (INS) and left anterior mid-cingulate cortex (MCC). Within group analysis indicated activations in these regions for IBS, but not for HCs, the latter showing deactivation of the ventrolateral PFC, left anterior INS and hippocampus. HCs also showed significant activation in the L middle and posterior INS. Conclusions. In response to an IBS symptom unrelated paradigm (attended fearful versus neutral faces), IBS show greater activity in prefrontal control regions [lPFC, medial PFC) as well as in dorsal anterior insula and left anterior mid-cingulate cortex. Results suggest greater recruitment of cognitive control mechanisms during presentation of emotionally salient or threat-related stimuli in IBS patients. Grants: K08 DK071626, R03 DK084169 (JSL) ,K23DK073451, R01 AT007137KT),T32 DK007180(CH),P50 DK064539, R24 AT002681, R01 DK048351(EAM)