Biology subjects

Plassmann, H.

Publications and source records attributed to Plassmann, H..

8 recordsLinked to original sources

bioRxiv2026

When adiposity and listening to reasons for behavioral change make food choices healthier: Behavioral and neural mediators of weight status effects on dietary decision-making following behavioral change interventions.

Resolving the inner conflict between improving eating habits (change talk) and sticking to unhealthy ones (sustain talk) is a key target in communication-based behavioral change interventions such as motivational interviewing (MI). Recent work has shown that this inner conflict affects how tastiness and healthiness are traded off in dietary decision-making. The effect varied with body mass index (BMI). Here we aimed to identify why participants with higher BMI shifted toward healthier food choices after listening to change talk. An evidence accumulation model found that BMI affected health evidence sampling when listening to change talk, and taste evidence sampling when listening to sustain talk. A serial mediation analysis showed that the effect of BMI on change-talk-induced health evidence sampling was explained by stronger resting-state connectivity in the ventromedial prefrontal cortex within the default mode network (DMN), which in turn predicted greater motivation to change eating habits. These cross-sectional findings indicate that the intrinsic functional organization of valuation-related regions within the DMN is associated with motivation to change. They provide evidence that these neural and behavioral factors need to align with contextual cues, such as weight status (as reflected by BMI), and with reasons for behavioral change to promote healthier decision-making.

neuroscience↗

bioRxiv2024

A structural MRI marker predicts individual differences in impulsivity and classifies patients with behavioral-variant frontotemporal dementia from matched controls

Impulsive decision-making is a symptom across many neuropsychiatric and neurological disorders. Yet, it is still unknown whether impulsivity can be predicted based on individual differences in brain structure. Here, we used machine-learning to develop a structural MRI signature of impulsivity, tested its validity in several independent samples, and assessed its diagnostic value in patients with behavioral variant frontotemporal dementia (bvFTD)--a neurodegenerative disease characterized by high impulsivity. The resulting whole-brain grey matter density pattern--the Structural Impulsivity Signature (SIS)--showed a good prediction-outcome correlation of r=0.35 (out-of-sample, p=0.0028) in the training sample of healthy adults (N=117) and significantly predicted individual differences in impulsivity in four other, independent studies (total N=626), including healthy and clinical participants with neuropsychiatric and neurological conditions. Further, the SIS separated bvFTD patients from controls with high accuracy (81% correct, p=0.002) and predicted impulsivity-related symptom severity among patients. The spatial distribution of weights in the SIS brain pattern highlights the key role of brain regions associated with affective processing in impulsivity. Together, these results provide evidence for a new structural neuromarker of individual differences in impulsivity that can be easily applied to new samples. Future studies can further assess its predictive value towards better prevention, diagnosis and treatment of mental disorders associated with impulsivity symptoms.

neuroscience↗

bioRxiv2024

High delay discounting relates to core symptoms and to pulvinar atrophy in frontotemporal dementia

Behavioural variant frontotemporal dementia (bvFTD) is a neurodegenerative disorder characterized by behavioural changes and atrophy in brain regions important for decision-making. Computations such as trading off between larger later (LL) and smaller sooner (SS) rewards -- called delay discounting in behavioural economics -- might be heavily impaired by bvFTD. In this cross-sectional study, our objectives were to investigate (1) whether bvFTD patients show higher delay discounting than healthy controls, (2) whether this maladaptive discounting correlates with impulsivity-related bvFTD symptoms, and (3) in which brain regions atrophy is related to bvFTDs steeper discounting. BvFTD patients (N=24) and matched controls (N=18) performed two delay discounting tasks: one with monetary rewards and one with food rewards. We compared discount rates (log(k)) in bvFTD patients and controls and tested their correlations with symptoms. We used participants structural MRI data and applied whole-brain mediation analyses to investigate brain structures mediating the effect of bvFTD on delay discounting. For both monetary and food rewards, delay discounting was significantly higher in bvFTD patients than in healthy controls. BvFTD patients higher discounting of both money and food was associated with their greater disinhibition and eating behaviour changes. Whole-brain mediation analyses revealed that (1) several brain regions (left thalamic pulvinar, left parahippocampal cortex, right temporal lobe) were predictive of steeper discounting of both money and food and (2) grey matter density in these brain regions, including most prominently the medial pulvinar, mediated the effect of bvFTD on discounting. The impulsive preference for sooner rewards captured by delay discounting might constitute a common mechanism of the behavioural symptoms of inhibition deficit and eating behaviour changes in bvFTD. Future studies could further investigate the potential role of medial pulvinar structural modifications as a transdiagnostic marker and a therapeutic target of impulsivity troubles.

neuroscience↗

bioRxiv2022

Investigation of whether oxytocin and trust play a role in placebo effects of marketing actions

Expectations about the quality of a medical treatment influence how much an inert treatment helps to improve patient well-being. Similarly, expectations about the quality of products influence how identical goods and services are evaluated differently after their consumption. One driver for such "placebo effects" in medical treatments is social cognition in the form of trust, which may be influenced by the hormone oxytocin. An open question is whether trust and oxytocin play similar roles in marketing placebo effects. To answer this question, we combined oxytocin administration (24 IU) and trust questionnaires in a pre-registered double-blind randomized between-subjects study design (Nfood tasting task = 223; Ncognitive performance task = 202). We could not find evidence that oxytocin and trust play a role in placebo effects of marketing actions. Together with other recent null findings from oxytocin administration studies, these findings question the role trust might play in different types of placebo effects.

neuroscience↗

bioRxiv2021

An fMRI-based brain marker predicts individual differences in delay discounting

Individual differences in impatience--how much we discount future compared to immediate rewards--are associated with general life outcomes and related to substance use, psychiatric diseases, and obesity. Here, we use machine-learning on fMRI activity during an intertemporal choice task to develop a brain marker of individual differences in delay discounting. Study 1 (N=110) was used as a training and cross-validation set, resulting in significant prediction accuracy (r = 0.49) and suggesting an interplay between brain regions associated with affect, value, and cognitive control. The validity of the brain marker was replicated in an independent data set (Study 2, N=145, r = 0.45). In both studies, responses of the marker significantly differed between overweight and lean individuals. This pattern is a first step towards a generalizable neuromarker of delay discounting and a potentially transdiagnostic phenotype, which can be used as a brain-based target measure in future studies.

neuroscience↗

bioRxiv2020

The brain's hedonic valuation system's resting-state connectivity predicts weight loss and correlates with leptin

Weight gain is often associated with the pleasure of eating foods rich in calories and lack of willpower to reduce such food cravings, but empirical evidence is sparse. Here we investigated the role that connectivity within the brains hedonic valuation system (BVS, the ventral striatum and the ventromedial prefrontal cortex) at rest plays (1) to predict weight gain or loss over time and (2) for homeostatic hormone regulation. We found that intrinsic connectivity within the BVS at rest (RSC) predicted out-of-sample weight changes over time in lean and obese participants. Counterintuitively, such BVS RSC was higher in lean versus obese participants before the obese participants underwent a drastic weight loss intervention (Roux-en-Y gastric bypass surgery, RYGB). The RYGB surgery increased BVS RSC in the obese after surgery. The obese participants increase in BVS RSC correlated with decreases in fasting state systemic leptin, a homeostatic hormone signalling satiety that has been previously linked to dopamine functioning. Taken together, our results indicate a first link between brain connectivity in reward circuits in a more tonic state at rest, homeostatic hormone regulation involved in dopamine functioning and ability to lose weight. Significance statementWith obesity rates on the rise, advancing our understanding of what factors drive peoples ability to lose and gain weight is crucial. This research is the first to link what we know about the brains hedonic valuation system (BVS) to weight loss and homeostatic hormone regulation. We found that connectivity at rest (RSC) within the BVS system predicted changes in weight, differentiated between lean and obese participants, and increased after a weight loss intervention (gastric bypass surgery). Interestingly, the extent to which BVS RSC improved after surgery correlated to decreases in circulating levels of the satiety hormone leptin. These findings are the first to reveal the neural and hormonal determinants of weight loss, combining hedonic and homeostatic drivers of (over-)eating.

neuroscience↗

bioRxiv2017

Red Bull Gives You Incentive Motivation: Understanding Placebo Effects of Energy Drinks on Human Cognitive Performance

The consumption of cognitive enhancers like energy drinks (EnD) is on the rise, but do they really improve cognitive performance, and, if yes, why? We examined two novel psychological mechanisms. First, we dissociated the role of expectations and actual consumption by crossing what people consumed--Red Bull Silver Edition or a similar-tasting Sprite soda--and what they thought they consumed. We found that participants performed better in a numerical Stroop task when they believed that they had consumed an EnD, irrespective of what they had actually consume, Second, we investigated the role of motivation for such a placebo effect of EnD. We found that expected, but not actual, consumption of EnD increased the effects of incentives on cognitive performance. Our results suggest that believing that one consumes an EnD increased participants motivation to perform and thus enhanced their performance.\n\nSignificance statementAcademic doping has become increasingly popular on campuses around the globe over the last years. However, it remains unknown if and how commercially available cognitive enhancers such as energy drinks (EnD) impact cognitive performance. We varied actual and believed consumption of an EnD and measured cognitive performance and its allocation according to the magnitude of points to earn. We found that the belief that one has consumed an EnD but not its actual consumption, increased cognitive performance specifically in high point trials compared to low point trials. These findings provide novel insights into motivational processes underpinning marketing-led expectancy effects, and contribute to the current public policy debate on the use and abuse of increased alertness and concentration claims for EnD.

neuroscience↗

bioRxiv2017

How context alters value: Price information recruits the brain’s valuation and affective regulation system for shaping experienced taste pleasantness

Informational cues such as the price of a wine can trigger expectations about its taste quality and thereby modulate the sensory experience on a reported and neural level. Yet it is unclear how the brain translates such expectations into sensory pleasantness. We used multilevel mediation analysis of neural and behavioral data obtained in participants who tasted identical wines cued with different prices. We found that the brain's valuation system (BVS) in concert with the anterior prefrontal cortex explained the effect of price cues on taste pleasantness ratings. The sensitivity of the BVS to rewards outside the taste domain moderated the strength of these effects. Moreover, brain mediators of price cue effects overlapped with brain regions previously found to be involved in placebo analgesia. These findings provide novel evidence for the fundamental role that neural pathways linked to motivation and affective regulation play for the effect of informational cues on sensory experiences.

neuroscience↗