Publications by authors named "Ralf Veit"

Aims: Central insulin has been shown to regulate eating behavior and cognitive processes in a sex-specific manner. Besides memory, the hippocampus is pivotal in the control of appetite. However, how insulin interacts with the hippocampal food cue response and the role of sex hormones in this context remain unclear.

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Objectives: Intrauterine exposure to gestational diabetes mellitus (GDM) increases the risk of obesity in the offspring, but little is known about the underlying neural mechanisms. The hippocampus is crucial for food intake regulation and is vulnerable to the effects of obesity. The purpose of the study was to investigate whether GDM exposure affects hippocampal functional connectivity during exposure to food cues using functional magnetic resonance imaging (fMRI).

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The hypothalamus is the key regulator for energy homeostasis and is functionally connected to striatal and cortical regions vital for the inhibitory control of appetite. Hence, the ability to non-invasively modulate the hypothalamus network could open new ways for the treatment of metabolic diseases. Here, we tested a novel method for network-targeted transcranial direct current stimulation (net-tDCS) to influence the excitability of brain regions involved in the control of appetite.

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Objectives: Intrauterine exposure to gestational diabetes mellitus (GDM) increases the risk of obesity in the offspring, but little is known about the underlying neural mechanisms. The hippocampus is crucial for food intake regulation and is vulnerable to the effects of obesity. The purpose of the study was to investigate whether GDM exposure affects hippocampal functional connectivity during exposure to food cues using functional magnetic resonance imaging.

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Article Synopsis
  • Insulin resistance in childhood increases the risk of type 2 diabetes and can affect brain activity related to behavior and metabolism.
  • A study with 53 children aged 7-11 measured their insulin sensitivity and brain responses to food cues using fMRI during glucose tests.
  • Results revealed that children with lower insulin sensitivity had distinct brain connectivity patterns, which could impact their eating behaviors and future diabetes risk.
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The hypothalamus has an abundant expression of sweet taste receptors that play a role in glucose sensing and energy homeostasis. Evidence suggests that liking "sweets" can be associated with weight gain, but the relationship between sweet taste preference and hypothalamic regulation of appetite is unknown. This study tested the hypothesis that sweet taste preference is associated with increased hypothalamic activation in response to glucose (a purported neural marker for weight gain risk) and greater longitudinal increases in body mass index (BMI).

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Aims: Insulin action in the brain influences cognitive processes, peripheral metabolism and eating behaviour. However, the influence of age and peripheral insulin sensitivity on brain insulin action remains unclear.

Materials And Methods: We used intranasal administration of insulin and functional magnetic resonance imaging in a randomized, placebo-controlled within-subject design in 110 participants (54 women, body mass index 18-49 kg/m , age 21-74 years).

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Article Synopsis
  • Insulin resistance in the brain negatively impacts weight maintenance and fat distribution, and there is limited understanding of how to restore brain insulin sensitivity in humans.
  • This study involved an 8-week supervised aerobic exercise program for 21 overweight and obese participants, using functional MRI to measure changes in brain insulin sensitivity before and after the intervention.
  • Results showed that regular exercise improved brain insulin action similar to that of healthy individuals, leading to better metabolism, reduced visceral fat, decreased hunger, and enhanced cognitive function, indicating that exercise can be a potential treatment for brain insulin resistance.
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The neural underpinnings of the integration of internal and external cues that reflect nutritional status are poorly understood in humans. The hypothalamus is a key integrative area involved in short- and long-term energy intake regulation. Hence, we examined the effect of hunger state on the hypothalamus network using functional magnetic resonance imaging.

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Background/objectives: Central insulin action influences cognitive processes, peripheral metabolism, and eating behavior. However, the contribution of obesity and sex on central insulin-mediated neural food cue processing still remains unclear.

Subjects/methods: In a randomized within-participant design, including two visits, 60 participants (30 women, BMI 18-32 kg/m, age 21-69 years) underwent a functional MRI task measuring blood oxygen level-dependent (BOLD) signal in response to visual food cues after intranasal insulin or placebo spray administration.

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Background: This study investigates the influence of maternal stress during pregnancy on maternal insulin sensitivity and Interleukin-6 (IL-6) levels in pregnant women (N = 277) in dependence of pre-pregnancy Body-Mass-Index (BMI).

Methods: Gestational diabetes was diagnosed in 80 women. We used the Patient Health Questionnaire (PHQ-D) to investigate maternal stress during pregnancy with a higher scoring indicating higher maternal stress level.

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Objective: Insulin action in the human brain reduces food intake, improves whole-body insulin sensitivity, and modulates body fat mass and its distribution. Obesity and type 2 diabetes are often associated with brain insulin resistance, resulting in impaired brain-derived modulation of peripheral metabolism. So far, no pharmacological treatment for brain insulin resistance has been established.

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Communication pathways of the hypothalamus with other brain regions and the periphery are critical to successfully control key physiological and psychological processes. With advanced functional magnetic resonance imaging (fMRI) techniques, it is possible to target hypothalamic function and infer discrete hypothalamus networks. Resting-state functional connectivity (RSFC) is a promising tool to study the functional organization of the brain and may act as a marker of individual differences and dysfunctions.

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Background: Behavioral and cognitive control are vital for healthy eating behavior. Patients with binge eating disorder (BED) suffer under recurrent binge eating episodes accompanied by subjective loss of control that results, among other factors, from increased impulsivity.

Methods: In the current study, we investigated the frontal network using functional near-infrared spectroscopy (fNIRS) during a food specific go/nogo task to assess response inhibition in 24 patients with BED (BMI range 22.

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Real-time fMRI neurofeedback is an increasingly popular neuroimaging technique that allows an individual to gain control over his/her own brain signals, which can lead to improvements in behavior in healthy participants as well as to improvements of clinical symptoms in patient populations. However, a considerably large ratio of participants undergoing neurofeedback training do not learn to control their own brain signals and, consequently, do not benefit from neurofeedback interventions, which limits clinical efficacy of neurofeedback interventions. As neurofeedback success varies between studies and participants, it is important to identify factors that might influence neurofeedback success.

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Although investigation of the brains of criminals began quite early in the history of psychophysiological research, little is known about brain plasticity of offenders with psychopathy. Building on our preliminary study reporting successful brain self-regulation using slow cortical potential (SCP) neurofeedback in offenders with psychopathy, we investigated the central nervous and autonomic peripheral changes occurring after brain self-regulation in a group of severe male offenders with psychopathy. Regarding the central nervous system, an overall suppression of the psychopathic overrepresentation of slow frequency bands was found, such as delta and theta band activity, after EEG neurofeedback.

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Neurofeedback training has been shown to influence behavior in healthy participants as well as to alleviate clinical symptoms in neurological, psychosomatic, and psychiatric patient populations. However, many real-time fMRI neurofeedback studies report large inter-individual differences in learning success. The factors that cause this vast variability between participants remain unknown and their identification could enhance treatment success.

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The amount of fat in ingested food dictates specific activation patterns in the brain, particularly in homeostatic and reward-related areas. Taste-specific brain activation changes have also been shown and the sensitivity to the oral perception of fat is associated with differential eating behavior and physiological parameters. The association between oral fat sensitivity and neuronal network functions has, however, not yet been defined.

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Background: Increased portion size is an essential contributor to the current obesity epidemic. The decision of how much to eat before a meal begins (i.e.

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Obesity is associated with altered responses to food stimuli in prefrontal brain networks that mediate inhibitory control of ingestive behavior. In particular, activity of the dorsolateral prefrontal cortex (dlPFC) is reduced in obese compared to normal-weight subjects and has been linked to the success of weight-loss dietary interventions. In a randomized controlled trial in overweight/obese subjects, we investigated the effect on eating behavior of volitional up-regulation of dlPFC activity via real-time functional magnetic resonance imaging (fMRI) neurofeedback training.

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While the significance of auditory cortical regions for the development and maintenance of speech motor coordination is well established, the contribution of somatosensory brain areas to learned vocalizations such as singing is less well understood. To address these mechanisms, we applied intermittent theta burst stimulation (iTBS), a facilitatory repetitive transcranial magnetic stimulation (rTMS) protocol, over right somatosensory larynx cortex (S1) and a nonvocal dorsal S1 control area in participants without singing experience. A pitch-matching singing task was performed before and after iTBS to assess corresponding effects on vocal pitch regulation.

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Background: Gastric distention contributes to meal termination. There is little research on the neural correlates of gastric distention by food. To date, neural measures have not been obtained concurrently with measurements of gastric distention.

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Obesity develops due to an imbalance between energy intake and expenditure. Besides the decision about what to eat, daily energy intake might be even more dependent on the decision about the portion size to be consumed. For decisions between different foods, attentional focus is considered to play a key role in the choice selection.

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Objective: Human obesity is associated with impaired central insulin signaling, and in very rare cases, severe obesity can be caused by congenital leptin deficiency. In such patients, leptin replacement results in substantial weight loss and improvement in peripheral metabolism.

Research Design And Methods: In a leptin-deficient patient, we investigated the impact of leptin substitution on central insulin action, as quantified by changes in neuronal activity after intranasal insulin application.

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Context: Insulin action in the human brain influences eating behavior, cognition, and whole-body metabolism. Studies investigating brain insulin rely on intranasal application.

Objective: To investigate effects of three doses of insulin and placebo as nasal sprays on the central and autonomous nervous system and analyze absorption of insulin into the bloodstream.

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