Neuroimaging and modulation in obesity and diabetes research: 10th anniversary meeting

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) hosted a workshop on April 16–17, 2019 titled, “Neuroimaging and Modulation in Obesity and Diabetes Research: 10th Anniversary Meeting”. This workshop convened creative scientists conducting basic and applied obesity and type 2 diabetes (T2D) neuroimaging and neuromodulation research, and celebrated the substantial progress made in the decade since a similar previous NIDDK workshop entitled “Neuroimaging in Obesity Research” on October 27–28, 2008. The goals of the 2008 workshop were to bring together an interdisciplinary audience to explore the state-of-the-art in the various disciplines related to obesity research that have successfully used neuroimaging, to identify obesity-related research questions that lend themselves best to imaging approaches, and to discuss best imaging practices, available opportunities and resources, and barriers to progress. To stimulate research in this area, the NIH issued a Request for Applications, DK-08-009 “Neuroimaging in Obesity Research (R01)” http://grants.nih.gov/grants/guide/rfa-files/RFA-DK-08-009.html . For the 2019 workshop, attendees considered three questions (1) What have we done? (2) What are we missing? and (3) What can we do to move forward? The World Health Organization estimates that the global incidence of overweight and obesity has tripled in the last 40 years [ 1 ]. Meanwhile, the number of people with T2D worldwide more than quadrupled, from 108 million in 1980 to more than 400 million in 2014 [ 2 ]. While the public health problem has been growing, researchers have focused on understanding the bidirectional relationships between obesity, T2D and brain structure and function, and how we can image and modulate the brain to advance our understanding of how it controls physiological and homeostatic functions as well as the cognitive and motivational states and traits critical for ingestive behaviors and metabolism [ 3 ]. The brain orchestrates what, when, and how much we eat and how our bodies use the nutrients provided by food. It drives our thirst and hunger, controls the sensory and emotional pleasures associated with eating and the decisions surrounding food choices. The complexity of feeding and metabolic circuitry could not have been imagined only 25 years ago, when the mediobasal hypothalamus was viewed as the “hunger center” and the lateral hypothalamus as the “satiety center” of the brain [ 4 ]. Now we know that feeding and metabolic control is mediated by discrete, genetically defined microcircuits within the mesoscopic anatomy of the brain [ 5 ]. The advent of neuroimaging technologies like functional magnetic resonance imaging (fMRI) has greatly improved our focus on the details of networks within the human brain [ 6 ]. The central control of metabolism involves hypothalamic signaling through the vagus nerve to the liver, fat and pancreas and the integration of reafferent signals in the brain stem and hypothalamus. These physiological signals are then projected to the anterior insula, which appears to regulate interoceptive attention to these signals before they are projected to higher-order brain networks that govern behavior [ 5 ]. These pathways are affected by obesity and T2D, which also lead to brain-peripheral system pathologies, impaired neuropsychological functions, and increased risk for Alzheimer’s disease and related disorders [ 7 ]. The 2019 workshop also addressed the advances that have enriched our understanding of these detailed networks and functions, which will help the community identify the gaps and research opportunities to be addressed over the next decade.