Issue 27, June 2012
bulletStress and the Brain
bulletUrban Stress Changes Brain
bulletStress: A Brain-Body Connection - Interview with Prof. Dirk Hellhammer
bulletThe Selfish Brain: Stress and Eating Behavior
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article1Stress and the Brain
It is no mystery that stress affects each of us differently; while a particular situation may be taxing for one group of individuals, another group may not feel any effects of stress. In this month's GCRI interview, Prof. Dirk Hellhammer of the University of Trier discusses the underlying biological explanation for this phenomenon: "People are genetically different. Some gene variants are stress protective, while others enhance stress vulnerability." Prof. Hellhammer has authored a book on this subject, entitled Stress: The Brain-Body Connection. To learn more about how your genes affect your stress levels, read Prof. Hellhammer's full GCRI interview here.

Scientists also have a better understanding of how stress affects the brain's physiology. Research published in the January 26 issue of Neuron provides evidence for a new mechanism of stress adaptation within the brain. This insight may give us a better understanding of why prolonged and repeated exposure to stress can lead to anxiety disorders and depression. Another study in Neuron investigated how repeated stress impairs memory.

City life and the stress factors that come with it, such as crowded spaces and higher noise levels, actually influence the brain's neural processes, thereby negatively impacting mental health. In the article below, Prof. Andreas Meyer-Lindenberg, the Director of the Central Institute of Mental Health in Mannheim, Germany, provides insight into how an urban environment affects the way the brain processes social stress. 

Urban Stress
article2Urban Stress Changes Brain
Text by Prof. Andreas Meyer-Lindenberg, Director, Central Institute of Mental Health, Medical Faculty Mannheim/University of Heidelberg, Mannheim, Germany

More than half of the world's population now lives in cities, and by 2050 more than two-thirds will live in urban areas. Cities have both health risks and benefits, but the effects on mental health are largely negative. Depression and anxiety disorders are more common in people living in cities, while the incidence of schizophrenia is strongly increased in people born and raised in cities. Although these findings have been widely attributed to social aspects of city life, the neural processes that could mediate such associations were unknown. In a paper published in Nature, a German group led by Andreas Meyer-Lindenberg, Central Institute of Mental Health, Mannheim, addressed this issue. Using fMRI, the researchers found that urban upbringing and city living changed the way in which the brain processes social stress. Current city living was associated with increased amygdala activity, a region in the brain important for control of negative emotions, while urban upbringing impacted the perigenual anterior cingulate cortex, a region that regulates amygdala activity. These findings identify distinct neural mechanisms for an established environmental risk factor for anxiety disorders, depression and schizophrenia, link the urban environment for the first time to social stress processing, and have potentially important implications for planning healthier cities in the future. 

Prof. Dirk Hellhammer
article3Stress: A Brain-Body Connection -
Interview with Prof. Dirk Hellhammer

In 2008, Prof. Dirk Hellhammer published Stress: The Brain-Body Connection, a book that provides clinicians, researchers, and students from the fields of psychiatry, psychology, neurobiology and psychoendocrinology with an overview of how knowledge from basic psychobiological research can benefit their patients.

In his book, Prof. Hellhammer introduces Neuropattern, the first translational diagnostic tool for the assessment of stress-related disorders. In this GCRI interview, Prof. Hellhammer addresses the physiological systems most strongly affected by stress, why people react to stress differently, and how Neuropattern can detect and test stress pathology.

Dirk Hellhammer studied psychology and biochemistry at the Universities of Würzburg and Frankfurt, and has been Professor of Clinical and Physiological Psychology at the University of Trier since 1986. His initial animal research focused on glia-neuron interactions, the septo-hippocampal system, and brain mechanisms participating in stress-related bodily disorders, while his clinical research dealt with peptic ulcer, anorexia nervosa, and ulcerative colitis. His group introduced the assessment of hormones in saliva and the Trier Social Stress Test as new tools in stress research. Other main research areas include prenatal programming of stress vulnerability and hypocortisolemic disorders, such as fibromyalgia, irritable bowel disease, or burnout. A recipient of numerous public and scientific awards, such as the German Psychology Award, Prof. Hellhammer will receive the Lifetime Achievement Award of the International Society for Psychoneuroendocrinology in September 2012 in New York. 

Stress and Eating Behaviour
article4The Selfish Brain: Stress and Eating Behavior
Source: Achim Peters et al., The selfish brain: stress and eating behavior, Frontiers in Neuroscience, May 30, 2011

How do stress, the stress response, and adaptation to the stress response influence eating behavior? This is a central question in brain research and medicine. According to the "selfish brain theory" of Achim Peters, Professor of Internal Medicine and obesity specialist at the University of Lübeck, Germany, the brain occupies a special hierarchical position in human energy metabolism. The experimental results presented in the article The Selfish Brain: Stress and Eating Behavior, published in Frontiers in Neuroscience, show that a stressed brain actively demands energy from the body in order to cover its increased energy needs. With this study, Prof. Peters and his co-authors present a logistic approach based on the principles of supply and demand. In this "cerebral supply chain" model, the brain is the final consumer. In order to illustrate the operating mode of the cerebral supply chain, the researchers took experimental data which made it possible to assess the supply, demand and needs of the brain under conditions of psychosocial stress. Data demonstrate that the stressed brain uses a mechanism referred to as "cerebral insulin suppression" to limit glucose fluxes into peripheral tissue, such as muscle and fat, and to enhance cerebral glucose supply. In addition, psychosocial stress elicits a marked increase in eating behavior in the post-stress phase. Subjects ingested more carbohydrates without any preference for sweet ingredients. These experimentally observed changes of cerebral demand, supply and need are integrated into a logistic framework describing the supply chain of the selfish brain. Read the entire article here

CR-Neuromodulation
article5CR-Neuromodulation: An Innovative Treatment Approach to Tinnitus

Stress can cause many health problems and acerbate others, including Tinnitus, a constant ringing in the ears. Millions of people hear and suffer from Tinnitus, the acoustic phenomenon that occurs without the existence of a real external auditory signal. The annoying continuous sound is not generated by the ear, but rather by abnormally synchronized neural action in characteristic brain areas. Self-organization and plasticity are fundamental mechanisms of the brain: Activity-dependent changes of synaptic connectivity enable the brain to learn and adapt. But, under pathological conditions, such as Tinnitus, synaptic connections may be abnormally strong, so that neurons fire in synchrony.

The Coordinated Reset (CR®) approach, developed by Prof. Peter Tass and his team at the Forschungszentrum Jülich, aims at shifting neuronal populations from a disease state to a healthy state. CR® is a sequence of mild stimuli, which specifically counteracts abnormal synchrony by desynchronization.

The patented CR® neuro-technology was established over the course of more than ten years at the Forschungszentrum Jülich. FDA-approved, it is already available for Tinnitus patients as acoustic CR®-neuromodulation in some European countries. This innovative approach, for which Prof. Tass received the 2011 German Innovation Award in Medicine, provides the opportunity to treat other diseases that are characterized by excessive synchronous nerve cell activity, such as Parkinson's disease, and will be studied in further clinical trials.

For more information, visit www.fz-juelich.de and www.anm-medical.com

Connectome event at the GCRI
article6Event Review: Connectome - Uniting People and Machines to Map the Mind

On June 6, 2012, during a panel discussion at the GCRI, Kavli Prize Laureate in Neuroscience Winfried Denk and long-time collaborator Sebastian Seung discussed microscopy and their groundbreaking, Internet- and game-based German-U.S. effort to map the connectome. Visit GCRI's new video page to watch the video.

The term connectome refers to a structural description of the neuronal connections in the brain. According to a doctrine known as connectionism, the properties of the human mind, from memories to mental disorders, are encoded in a distinctive pattern of neural connections. Since the connections of individual neurons differ from brain to brain, they contribute to a person's uniqueness. For years, connectionism has inspired a new generation of scientists to search for the connectome, a map of links between individual neurons in the brain. To date, the only connectome that is known in its entirety is that of the worm, c. elegans. Twelve years were required to identify the worm's 302 neurons and its over 7,000 connections. The human brain consists of 100 billion neurons that are interconnected in 10,000 different ways. To map a human connectome would require extensive use of supercomputers and untold man-hours.

Visit the Connectome event page for the full article. 

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