Background: Loss of motivation is a characteristic feature of several psychiatric and neurological disorders. However, the neural mechanisms underlying human motivation are far from being understood. Here, we investigate the role that the frontopolar cortex (FPC) plays in motivating cognitive and physical effort exertion by computing subjective effort equivalents.
Methods: We manipulated neural processing with transcranial direct current stimulation targeting the FPC while 141 healthy participants decided whether or not to engage in cognitive or physical effort to obtain rewards.
Results: We found that brain stimulation targeting the FPC increased the amount of both types of effort participants were willing to exert for rewards.
Conclusions: Our findings provide important insights into the neural mechanisms involved in motivating effortful behavior. Moreover, they suggest that considering the motivation-related activity of the FPC could facilitate the development of treatments for the loss of motivation commonly seen in psychiatric and other neurological disorders.
In magnetic resonance imaging, precise measurements of longitudinal relaxation time (T1) is crucial to acquire useful information that is applicable to numerous clinical and neuroscience applications. In this work, we investigated the precision of T1 relaxation time as measured using the variable flip angle method with emphasis on the noise propagated from radiofrequency transmit field (B+1) measurements. The analytical solution for T1 precision was derived by standard error propagation methods incorporating the noise from the three input sources: two spoiled gradient echo (SPGR) images and a B+1 map. Repeated in vivo experiments were performed to estimate the total variance in T1 maps and we compared these experimentally obtained values with the theoretical predictions to validate the established theoretical framework. Both the analytical and experimental results showed that variance in the B+1 map propagated comparable noise levels into the T1 maps as either of the two SPGR images. Improving precision of the B+1 measurements significantly reduced the variance in the estimated T1 map. The variance estimated from the repeatedly measured in vivo T1 maps agreed well with the theoretically-calculated variance in T1 estimates, thus validating the analytical framework for realistic in vivo experiments. We concluded that for T1 mapping experiments, the error propagated from the B+1 map must be considered. Optimizing the SPGR signals while neglecting to improve the precision of the B+1 map may result in grossly overestimating the precision of the estimated T1 values.
Background: Physicians often do not initiate or intensify treatments when clearly warranted, a phenomenon known as therapeutic inertia (TI). Limited information is available on educational interventions to ameliorate knowledge-to-action gaps in TI.
Objectives: To evaluate the feasibility and efficacy of an educational intervention compared to usual care among practicing neurologists caring for patients with multiple sclerosis (MS).
Methods: We conducted a pilot double-blind, parallel-group, randomized clinical trial. Inclusion criteria included neurologists who are actively involved in managing MS patients. Participants were exposed to 20 simulated case-scenarios (10 cases at baseline, and 10 cases post-randomization to usual care vs. educational intervention) of relapsing–remitting MS with moderate or high risk of disease progression. The educational intervention employed a traffic light system (TLS) to facilitate decisions, allowing participants to easily recognize high-risk scenarios requiring treatment escalation. We also measured differences between blocks to invoke decision fatigue. The control group responded as they would do in their usual clinical practice not exposed to the educational intervention. The primary feasibility outcome was the proportion of participants who completed the study and the proportion of participants who correctly identified a high-risk case-scenario with the “red traffic light.” Secondary outcomes included decision fatigue (defined as an increment of TI in the second block of case-scenarios compared to the first block) and the efficacy of the educational intervention measured as a reduction in TI for MS treatment.
Results: Of 30 neurologists invited to be part of the study, the participation rate was 83.3% (n = 25). Of the 25 participants, 14 were randomly assigned to the control group and 11 to the intervention group. TI was present in 72.0% of participants in at least one case scenario. For the primary feasibility outcome, the completion rate of the study was 100% (25/25 participants). Overall, 77.4% of participants correctly identified the “red traffic light” for clinical-scenarios with high risk of disease progression. Similarly, 86.4% of participants correctly identified the “yellow traffic light” for cases that would require a reassessment within 6–12 months. For the secondary fatigue outcome, within-group analysis showed a significant increased prevalence of TI in the second block of case-scenarios (decision fatigue) among participants randomized to the control group (TI pre-intervention 57.1% vs. TI post-intervention 71.4%; p = 0.015), but not in the active group (TI pre-intervention 54.6% vs. TI post-intervention 63.6%; p = 0.14). For the efficacy outcome, we found a non-significant reduction in TI for the targeted intervention compared to controls (22.6 vs. 33.9% post-intervention; OR 0.57; 95% CI 0.26–1.22).
Conclusion: An educational intervention applying the TLS is feasible and shows some promising results in the identification of high-risk scenarios to reduce decision fatigue and TI. Larger studies are needed to determine the efficacy of the proposed educational intervention.
Obese individuals have been shown to exhibit abnormal sensitivity to rewards and reward-predicting cues as for example food-associated cues frequently used in advertisements. It has also been shown that food-associated cues can increase goal-directed behavior but it is currently unknown, whether this effect differs between normal-weight, overweight, and obese individuals. Here, we investigate this question by using a Pavlovian-to-instrumental transfer (PIT) task in normal-weight (N = 20), overweight (N = 17), and obese (N = 17) individuals. Furthermore, we applied eye tracking during Pavlovian conditioning to measure the participants’ conditioned response as a proxy of the incentive salience of the predicted reward. Our results show that the goal-directed behavior of overweight individuals was more strongly influenced by food-predicting cues (i.e., stronger PIT effect) than that of normal-weight and obese individuals (p < 0.001). The weight groups were matched for age, gender, education, and parental education. Eye movements during Pavlovian conditioning also differed between weight categories (p < 0.05) and were used to categorize individuals based on their fixation style into “high eye index” versus “low eye index” as well. Our main finding was that the fixation style exhibited a complex interaction with the weight category. Furthermore, we found that normal-weight individuals of the group “high eye index” had higher body mass index within the healthy range than individuals of the group “low eye index” (p < 0.001), but this relationship was not found within in the overweight or obese groups (p > 0.646). Our findings are largely consistent with the incentive sensitization theory predicting that overweight individuals are more susceptible to food-related cues than normal-weight controls. However, this hypersensitivity might be reduced in obese individuals, possibly due to habitual/compulsive overeating or differences in reward valuation.
Objectives: Limited information is available on physician-related factors influencing therapeutic inertia (TI) in multiple sclerosis (MS). Our aim was to evaluate whether physicians’ risk preferences are associated with TI in MS care, by applying concepts from behavioral economics.
Design: In this cross-sectional study, participants answered questions regarding the management of 20 MS case scenarios, completed 3 surveys, and 4 experimental paradigms based on behavioral economics. Surveys and experiments included standardized measures of aversion ambiguity in financial and health domains, physicians’ reactions to uncertainty in patient care, and questions related to risk preferences in different domains. The primary outcome was TI when physicians faced a need for escalating therapy based on clinical (new relapse) and magnetic resonance imaging activity while patients were on a disease-modifying agent.
Results: Of 161 neurologists who were invited to participate in the project, 136 cooperated with the study (cooperation rate 84.5%) and 96 completed the survey (response rate: 60%). TI was present in 68.8% of participants. Similar results were observed for definitions of TI based on modified Rio or clinical progression. Aversion to ambiguity was associated with higher prevalence of TI (86.4% with high aversion to ambiguity vs. 63.5% with lower or no aversion to ambiguity; p = 0.042). In multivariate analyses, high aversion to ambiguity was the strongest predictor of TI (OR 7.39; 95%CI 1.40–38.9), followed by low tolerance to uncertainty (OR 3.47; 95%CI 1.18–10.2).
Conclusion: TI is a common phenomenon affecting nearly 7 out of 10 physicians caring for MS patients. Higher prevalence of TI was associated with physician’s strong aversion to ambiguity and low tolerance of uncertainty.
Der Erfolg von Unternehmen wie Microsoft und Amazon hat zur Marktdominanz einzelner Anbieter geführt und deren Besitzer immens reich gemacht. Ein Kommentar von David Dorn.
Derzeit ist nicht erkennbar, dass es eine klare Rolle für Kryptowährungen gibt, die für legitime Zwecke nicht ebenso gut durch traditionelle Währungen erfüllt werden könnte. Ein Kommentar von Joachim Voth.
Die Uni Zürich ist die forschungsstärkste VWL-Hochschule im deutschsprachigen Raum und peilt nun die Weltspitze an. Direktor Rainer Winkelmann über die Zukunft und die Probleme der Zunft.
We propose a model consistent with two observations. First, the tax rates adopted by different countries are generally uncorrelated with their growth performance. Second, countries that drastically reduce private incentives to invest severely hurt their growth performance. In our model, the effects of taxation on growth are highly nonlinear. Low tax rates have a very small impact on long-run growth rates. But as tax rates rise, their negative impact on growth rises dramatically. The median voter chooses tax rates that have a small impact on growth prospects, making the relation between tax rates and economic growth difficult to measure empirically.
We study the role of foreign-born workers in the growth of employment in STEM occupations since 1980. Given the importance of employment in these fields for research and innovation, we consider their role in a model featuring endogenous non-routine-biased technical change. We use this model to quantify the impact of high-skilled immigration, and the increasing tendency of such immigrants to work in innovation, on the pace of non-routine-biased technical change, the polarization of employment opportunities, and the evolution of wage inequality since 1980.
