title: Insulin action in the human brain: evidence from neuroimaging studies.
abstract: Thus far, little is known about the action of insulin in the human brain. Nonetheless, recent advances in modern neuroimaging techniques, such as functional magnetic resonance imaging (fMRI) or magnetoencephalography (MEG), have made it possible to investigate the action of insulin in the brain in humans, providing new insights into the pathogenesis of brain insulin resistance and obesity. Using MEG, the clinical relevance of the action of insulin in the brain was first identified, linking cerebral insulin resistance with peripheral insulin resistance, genetic predisposition and weight loss success in obese adults. Although MEG is a suitable tool for measuring brain activity mainly in cortical areas, fMRI provides high spatial resolution for cortical as well as subcortical regions. Thus, the action of insulin can be detected within all eating behaviour relevant regions, which include regions deeply located within the brain, such as the hypothalamus, midbrain and brainstem, as well as regions within the striatum. In this review, we outline recent advances in the field of neuroimaging aiming to investigate the action of insulin in the human brain using different routes of insulin administration. fMRI studies have shown a significant insulin-induced attenuation predominantly in the occipital and prefrontal cortical regions and the hypothalamus, successfully localising insulin-sensitive brain regions in healthy, mostly normal-weight individuals. However, further studies are needed to localise brain areas affected by insulin resistance in obese individuals, which is an important prerequisite for selectively targeting brain insulin resistance in obesity.
authors.affiliation: Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany.|German Center for Diabetes Research, Neuherberg, Germany.|Institute of Medical Psychology and Behavioral Neurobiology/fMEG, Eberhard Karls University Tübingen, Tübingen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kullmann
authors.affiliation: Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany.|German Center for Diabetes Research, Neuherberg, Germany.|Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tübingen, Tübingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Heni
authors.affiliation: Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany.|German Center for Diabetes Research, Neuherberg, Germany.|Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tübingen, Tübingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Fritsche
authors.affiliation: Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University of Tübingen, Tübingen, Germany.|German Center for Diabetes Research, Neuherberg, Germany.|Institute of Medical Psychology and Behavioral Neurobiology/fMEG, Eberhard Karls University Tübingen, Tübingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Preissl
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography
chemical_list: D007328:Insulin
keywords: brain; functional magnetic resonance imaging; insulin resistance; neuroimaging; obesity