changes in neural resources are required to understand how these declines arise and how they are
counteracted by mechanisms mobilising remaining resources. Lack of sleep destabilises and impairs
cognitive performance and renders mistakes more likely, presumably by functionally depleting neural
resources. In this project we aim to establish and characterise sleep deprivation (SD) as a model to
test and simulate the effects of declining cognitive functions as a result of reduced availability of neural resources (a "functional loss of resources”) in humans. On the other hand, cognitive control may adaptively mobilise resources according to needs and availability. To probe neural resources and mechanisms maintaining cognitive functions in spite of SD effects, cognitive control is investigated using a task allowing us to disentangle contributions of the posterior medial frontal, lateral frontal, and occipital cortices which together form a neural network that facilitates behavioural adaptations. Employing model-based and multivariate pattern analyses (MVPA) to neuroimaging data in rested wakefulness (RW) and after SD, the contributions of individual regions and the network itself will be investigated. Structural predictors of resource vs. vulnerability to SD, such as intracortical myelination, will be explored using microstructural MRI. Orexin (OX) is a neuropeptide that, in interaction with the noradrenergic (NA) system, stabilises and adjusts arousal and may have the potential to revert SD effects. Therefore, its role of in stabilising and restoring neural resources will be studied in pharmacological challenge studies.