Northwestern University

About: Northwestern University is a education organization based out in Evanston, Illinois, United States. It is known for research contribution in the topics: Population & Medicine. The organization has 75430 authors who have published 188857 publications receiving 9463252 citations. The organization is also known as: Northwestern & NU.

Changes in brain activity related to eating chocolate: from pleasure to aversion.

Abstract: We performed successive H(2)(15)O-PET scans on volunteers as they ate chocolate to beyond satiety. Thus, the sensory stimulus and act (eating) were held constant while the reward value of the chocolate and motivation of the subject to eat were manipulated by feeding. Non-specific effects of satiety (such as feelings of fullness and autonomic changes) were also present and probably contributed to the modulation of brain activity. After eating each piece of chocolate, subjects gave ratings of how pleasant/unpleasant the chocolate was and of how much they did or did not want another piece of chocolate. Regional cerebral blood flow was then regressed against subjects' ratings. Different groups of structures were recruited selectively depending on whether subjects were eating chocolate when they were highly motivated to eat and rated the chocolate as very pleasant [subcallosal region, caudomedial orbitofrontal cortex (OFC), insula/operculum, striatum and midbrain] or whether they ate chocolate despite being satiated (parahippocampal gyrus, caudolateral OFC and prefrontal regions). As predicted, modulation was observed in cortical chemosensory areas, including the insula and caudomedial and caudolateral OFC, suggesting that the reward value of food is represented here. Of particular interest, the medial and lateral caudal OFC showed opposite patterns of activity. This pattern of activity indicates that there may be a functional segregation of the neural representation of reward and punishment within this region. The only brain region that was active during both positive and negative compared with neutral conditions was the posterior cingulate cortex. Therefore, these results support the hypothesis that there are two separate motivational systems: one orchestrating approach and another avoidance behaviours.

Does the Source of Capital Affect Capital Structure

Abstract: Prior work on leverage implicitly assumes capital availability depends solely on firm characteristics. However, market frictions that make capital structure relevant may also be associated with a firm's source of capital. Examining this intuition, we find firms that have access to the public bond markets, as measured by having a debt rating, have significantly more leverage. Although firms with a rating are fundamentally different, these differences do not explain our findings. Even after controlling for firm characteristics that determine observed capital structure, and instrumenting for the possible endogeneity of having a rating, firms with access have 35% more debt. Copyright 2006, Oxford University Press.

Chapter 15 Job search and labor market analysis

Abstract: Publisher Summary The theory of search is an important young actor on the stage of economic analysis. It plays a major part in a dramatic new field, the economics of information and uncertainty. By exploiting its sequential statistical decision theoretic origins, the search theory has found success by specializing in the portrayal of a decision-maker who must acquire and use information to take rational action in an ever changing and uncertain environment. Although the search theory's specific characterizations can now be found in many arenas of applied economic analysis, most of the theory's original roles are found in the labor economics literature. This chapter reviews the search theory's performances to date in labor market analysis. In a given population of labor force participants, the steady state fractions that are unemployed are equal to the product of the average frequency and duration of unemployment spells. The data sources reveal that unemployment spells are typically frequent but short in all phases of the business cycle, although counter-cyclic increases in both frequency and duration contribute to the well-known time series behavior of unemployment rates.

Habit Persistence, Asset Returns, and the Business Cycle

Abstract: Two modifications are introduced into the standard real-business-cycle model: habit preferences and a two-sector technology with limited intersectoral factor mobility. The model is consistent with the observed mean risk-free rate, equity premium, and Sharpe ratio on equity. In addition, its business-cycle implications represent a substantial improvement over the standard model. It accounts for persistence in output, comovement of employment across different sectors over the business cycle, the evidence of "excess sensitivity" of consumption growth to output growth, and the "inverted leading-indicator property of interest rates," that interest rates are negatively correlated with future output.