Differential effects of hunger and satiety on insular cortex and hypothalamic functional connectivity

• Published in: The European journal of neuroscience Vol. 43; no. 9; pp. 1181 - 1189
• Main Authors: Wright, Hazel, Li, Xiaoyun, Fallon, Nicholas B., Crookall, Rebecca, Giesbrecht, Timo, Thomas, Anna, Halford, Jason C.G., Harrold, Joanne, Stancak, Andrej
• Format: Journal Article
• Language: English
• Published: France Blackwell Publishing Ltd 01.05.2016; John Wiley and Sons Inc
• Subjects: Adult; appetite; Behavioural Neuroscience; Brain Mapping; Cerebral Cortex - physiology; Fasting - psychology; Female; fMRI; homeostatic energy balance; Humans; Hunger - physiology; Hypothalamus - physiology; Magnetic Resonance Imaging; Male; Research Report; fMRI; homeostatic energy balance; appetite
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/ejn.13182

The insula cortex and hypothalamus are implicated in eating behaviour, and contain receptor sites for peptides and hormones controlling energy balance. The insula encompasses multi‐functional subregions, which display differential anatomical and functional connectivities with the rest of the brain. This study aimed to analyse the effect of fasting and satiation on the functional connectivity profiles of left and right anterior, middle, and posterior insula, and left and right hypothalamus. It was hypothesized that the profiles would be altered alongside changes in homeostatic energy balance. Nineteen healthy participants underwent two 7‐min resting state functional magnetic resonance imaging scans, one when fasted and one when satiated. Functional connectivity between the left posterior insula and cerebellum/superior frontal gyrus, and between left hypothalamus and inferior frontal gyrus was stronger during fasting. Functional connectivity between the right middle insula and default mode structures (left and right posterior parietal cortex, cingulate cortex), and between right hypothalamus and superior parietal cortex was stronger during satiation. Differences in blood glucose levels between the scans accounted for several of the altered functional connectivities. The insula and hypothalamus appear to form a homeostatic energy balance network related to cognitive control of eating; prompting eating and preventing overeating when energy is depleted, and ending feeding or transferring attention away from food upon satiation. This study provides evidence of a lateralized dissociation of neural responses to energy modulations. We studied the functional connectivity of insula cortex and hypothalamus under conditions of hunger and satiety. Manipulation of the homeostatic energy balance provokes changes in functional connectivity between insula, hypothalamus, and a fronto‐parietal network. Alterations in connectivity appear to be related to cognitive control of eating: prompting eating, preventing overeating, and transferring attention away from food.