With age, the brain undergoes comprehensive changes in its function and physiology. Cerebral metabolism and blood supply are among the key physiologic processes supporting the daily function of the brain and may play an important role in age-related cognitive decline. Using MRI, it is now possible to make quantitative assessment of these parameters in a noninvasive manner. In the present study, we concurrently measured cerebral metabolic rate of oxygen (CMRO(2)), cerebral blood flow (CBF), and venous blood oxygenation in a well-characterized healthy adult cohort from 20 to 89 years old (N = 232). Our data showed that CMRO(2) increased significantly with age, while CBF decreased with age. This combination of higher demand and diminished supply resulted in a reduction of venous blood oxygenation with age. Regional CBF was also determined, and it was found that the spatial pattern of CBF decline was heterogeneous across the brain with prefrontal cortex, insular cortex, and caudate being the most affected regions. Aside from the resting state parameters, the blood vessels' ability to dilate, measured by cerebrovascular reactivity to 5% CO(2) inhalation, was assessed and was reduced with age, the extent of which was more prominent than that of the resting state CBF.

Emotional stimuli have been shown to preferentially engage initial attention but their sustained effects on neural processing remain largely unknown. The present study evaluated whether emotional faces engage sustained neural processing by examining the attenuation of neural repetition suppression to repeated emotional faces. Repetition suppression of neural function refers to the general reduction of neural activity when processing a repeated stimulus. Preferential processing of emotional face stimuli, however, should elicit sustained neural processing such that repetition suppression to repeated emotional faces is attenuated relative to faces with no emotional content. We measured the reduction of functional magnetic resonance imaging signals associated with immediate repetition of neutral, angry and happy faces. Whereas neutral faces elicited the greatest suppression in ventral visual cortex, followed by angry faces, repetition suppression was the most attenuated for happy faces. Indeed, happy faces showed almost no repetition suppression in part of the right-inferior occipital and fusiform gyri, which play an important role in face-identity processing. Our findings suggest that happy faces are associated with sustained visual encoding of face identity and thereby assist in the formation of more elaborate representations of the faces, congruent with findings in the behavioral literature.

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Over the last two decades, researchers in operations management have increasingly leveraged laboratory experiments to identify key behavioral insights. These experiments inform behavioral theories of operations management, impacting domains including inventory, supply chain management, queuing, forecasting, and sourcing. Yet, until now, the replicability of most behavioral insights from these laboratory experiments has been untested. We remedy this with the first large-scale replication study in operations management. With the input of the wider operations management community, we identify 10 prominent experimental operations management papers published in Management Science, which span a variety of domains, to be the focus of our replication effort. For each paper, we conduct a high-powered replication study of the main results across multiple locations using original materials (when available and suitable). In addition, our study tests replicability in multiple modalities (in-person and online) due to laboratory closures during the COVID-19 pandemic. Our replication study contributes new knowledge about the robustness of several key behavioral theories in operations management and contributes more broadly to efforts in the operations management field to improve research transparency and reliability. This paper was accepted by David Simchi-Levi, operations management. Funding: The authors gratefully acknowledge financial support from Cornell University, the University of South Carolina, the University of Texas at Dallas, the University of Michigan, and the University of Wisconsin-Madison. Supplemental Material: The data files and online appendices are available at https://doi.org/10.1287/mnsc.2023.4866 .

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