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The circuit that the suprachiasmatic nucleus uses to control the daily glucocorticoids surge remains unknown. Here, authors show two parallel neural pathways from the hypothalamus that control the daily surge of corticosteroid by mapping the circuits from the SPZ and DMH to the PVH.

Neurons in the median preoptic nucleus that express the prostaglandin EP3 receptor produce prolonged hypothermic responses or hyperthermic responses, respectively, following brief activation or inhibition.

Supramammillary nucleus (SuM) neurons have been studied in the context of REM sleep but their possible role in mediating wakefulness is not known. Here the authors elucidate the distinct functional contributions of three subpopulations in the SuM on electrographical and behavioral arousal in mice using genetically targeted approaches.

The dorsal pons in the brainstem is packed with clusters of neurons, including the parabrachial nucleus, that are involved in many vital functions. Here, authors use single nucleus RNA sequencing and MERFISH to create a spatially defined transcriptional atlas of this region.

A population of excitatory neurons has been found to have a key role in controlling body temperature in rodents. The discovery adds to a body of work that is raising questions about long-standing models of thermoregulation.

The parabrachial nucleus contains separate populations of neurons that respond to elevated CO₂ with EEG arousal and increased breathing. Here we report that the parabrachial respiratory neurons express FoxP2 and are required for respiratory responses to elevated CO₂.

Sleep and wakefulness is stabilized by a population of orexin-expressing neurons. In this study, the authors demonstrate how these neurons drive arousal by silencing sleep-promoting neurons in the ventrolateral preoptic nucleus.

Todd et al. show a daily rhythm in aggression propensity in male mice and reveal a novel polysynaptic circuit within the hypothalamus by which the central circadian clock (the suprachiasmatic nucleus) influences neurons that regulate attack behavior.

In mice, brain neurons that respond during either mating or aggression exhibit spatial overlap, and some even respond during both. This may help to explain the relationship between sex and violence in human behaviour. See Article p.221

Dorsal raphe 5HT(DR^Sert) neurons regulate arousal from hypercapnia by their projections to the neurons in the external lateral parabrachial nucleus (PBel) that are glutamatergic and also express calcitonin gene related peptide (PBel^CGRP). The DR^Sert input to the PBel modulates the arousal system to rising levels of blood CO₂, and may be mediated by 5HT_2a receptors on the PBel^CGRP neurons.

Light makes migraines worse. The authors show that this effect can be mediated by intrinsically photosensitive retinal ganglion cells projecting onto thalamic neurons that also receive nociceptive input from the dura mater.

Anatomical lesions of the preoptic area (POA) can cause sleep loss while electrical, chemical, or thermal stimulation of POA can induce sleep. To better understand the exact neural function of the POA, this study shows that galanin and GABA+ inhibitory neurons in the ventrolateral POA that project to the wake-promoting tuberomammillary nucleus promote sleep in a stimulation frequency dependent manner.

Using a combination of targeted activation and optogenetic-based mapping in mice, this study demonstrates that sleep-active GABAergic neurons in the medullary parafacial zone promote slow wave sleep and cortical slow wave activity and uncovers functional circuit connections linking these neurons with the cortex.

Orexins are known to regulate sleep and feeding, but a study in Nature now shows that they are also involved in drug-seeking behavior. This suggests a larger role for orexin-producing neurons as an interface between internal states and motivated behaviors.

Laser microdissection and microarrays are used to assess 900 precise subdivisions of the brains from three healthy men with 60,000 gene expression probes; the resulting atlas allows comparisons between humans and other animals, and will facilitate studies of human neurological and psychiatric diseases.

In mouse, an axonal connectivity map showing the wiring patterns across the entire brain has been created using an EGFP-expressing adeno-associated virus tracing technique, providing the first such whole-brain map for a vertebrate species.

An orally available drug enters the brain and interferes with signaling of orexin neuropeptides—providing a potential treatment for sleep disorders and possibly addiction (pages 150–155).

Combining cell group specific gene expression patterns with recent technologies has provided insights into brain circuitry. A new resource may make it possible for those studying the hypothalamus to use these techniques as well.

Acute exposure to a variety of pathogens or inflammatory insults leads to a well-characterized set of responses in the CNS, aimed at promoting the clearance of the infecting agent. In this review, the authors examine the various symptoms of this 'sickness syndrome' and the actions of prostaglandins in linking inflammation with these CNS responses.