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A5 -Neurocognitive Models of Behavioral Control in Obesity - The modulating effects of dynamic changes in central dopaminergic tone

The neurotransmitter dopamine (DA) plays a central role in several cognitive key domains such as (food) motivation, reinforcement learning, and memory. Our recent results point towards (a) prominent alterations in these domains in overweight and obesity and (b) a non-linear relationship between markers of obesity and the central nervous transmission efficacy of dopamine. In particular, moderately obese subjects may exhibit lower levels of dopamine compared to normal-weight subjects whereas severely obese subjects may have an abundance of central dopamine. This has important implications (1) for the assignment to experimental groups, since pooling across moderately and severely obese subjects is likely to result in a null-finding, and (2) for the expected direction of neural and behavioural changes. Due to its central role, alterations in dopaminergic transmission impact on very different behaviors, ranging from eating to decision making and learning. Moreover, opposing patterns of change in dopaminergic transmission suggest a differential pattern of cognitive alterations in moderately and severely obese subjects, giving rise to the assumption of separate subpopulations. Importantly, moderately and severely obese subjects should benefit from opposing manipulations to dopaminergic tone. In the proposed project we will test these predictions experimentally. Specifically, we will test the effects of pharmacological manipulation to central dopaminergic transmission in moderately and severely obese subjects utilizing behavioral testing, functional magnetic resonance imaging (fMRI), and neurocognitive modelling, the latter providing a direct link of behavioral and neural effects on the individual level. Further, we will investigate the interaction of ‘natural’, i.e. genetic, modulators of DA transmission with obesity- and diet-associated alterations in different brain regions.

PD Dr. Jane Neumann, Integrated Research and Treatment Center AdiposityDiseases (co-PI 2013–2016)

Abbildung 1: (A) Quadratic relationship between Positron Emission Tomography (PET) markers of dopaminergic transmission and body mass index (BMI). BP: Binding Potential of PET tracer. (B) Inverted U-shaped relationship between reward sensitivity and BMI. (C) Modulatory effect of BMI on brain activity associated with the volitional regulation of food craving. BMI is nonlinearly related to BOLD activation in clusters in left putamen, amygdala, and insula (D). (E) Inverted u-shaped relationship between BMI and BOLD effect size in the left putamen. (Colour-coding refers to t-values, p<.001 voxel level, p<.05 Family Wise Error corrected on the cluster level, whole brain).

PROJECT TEAM

Lieneke Janssen, PostDoc

Franziska Rausch, Phd student

Hendrik Hartmann, Phd student

Suse Prejawa, Project manager