The regulation of brain states by neuroactive substances distributed via the cerebrospinal fluid; a review.

Contains fulltext : 83842.pdf (publisher's version ) (Open Access)The cerebrospinal fluid (CSF) system provides nutrients to and removes waste products from the brain. Recent findings suggest, however, that in addition, the CSF contains message molecules in the form of actively released neuroactive substances. The concentrations of these vary between locations, suggesting they are important for the changes in brain activity that underlie different brain states, and induce different sensory input and behavioral output relationships.The cranial CSF displays a rapid caudally-directed ventricular flow followed by a slower rostrally-directed subarachnoid flow (mainly towards the cribriform plate and from there into the nasal lymphatics). Thus, many brain areas are exposed to and can be influenced by substances contained in the CSF. In this review we discuss the production and flow of the CSF, including the mechanisms involved in the regulation of its composition. In addition, the available evidence for the release of neuropeptides and other neuroactive substances into the CSF is reviewed, with particular attention to the selective effects of these on distant downstream receptive brain areas. As a conclusion we suggest that (1) the flowing CSF is involved in more than just nutrient and waste control, but is also used as a broadcasting system consisting of coordinated messages to a variety of nearby and distant brain areas; (2) this special form of volume transmission underlies changes in behavioral states

Bringing Society Back in : Actors, Networks, and Systems in Public Policy

A key thesis of this contribution is that the analysis of policy processes in the last decades has focused too much on governmental and conventional political actors, on the one hand, and too much on actor-centered bottom-up perspectives. As the microfoundation of social explanations has moved to the fore, actor constellations became the core of policy explanations and contextual factors and systemic perspectives moved into the background. The chapter proposes a renewed perspective on public policy with the aim to bring social factors back into play, particularly at macrostructural level. This means not only that non-governmental, civil society organizations and social relations should be given greater consideration, but even more important are various forms of structural differentiation at the macro level of societies which should be reintegrated into policy explanations.publishe