Although the neural circuitry underlying homeostatic sleep regulation is little understood, cortical neurons immunoreactive for neuronal nitric oxide synthase (nNOS) and the neurokinin-1 receptor (NK1) have been proposed to be involved in this physiological process. By systematically manipulating the durations of sleep deprivation and subsequent recovery sleep, we show that activation of cortical nNOS/NK1 neurons is directly related to non-rapid eye movement (NREM) sleep time, NREM bout duration, and EEG δ power during NREM sleep, an index of preexisting homeostatic sleep drive. Conversely, nNOS knockout mice show reduced NREM sleep time, shorter NREM bouts, and decreased power in the low δ range during NREM sleep, despite constitutively elevated sleep drive. Cortical NK1 neurons are still activated in response to sleep deprivation in these mice but, in the absence of nNOS, they are unable to up-regulate NREM δ power appropriately. These findings support the hypothesis that cortical nNOS/NK1 neurons translate homeostatic sleep drive into up-regulation of NREM δ power through an NO-dependent mechanism.T he electrical activity of the cerebral cortex has been used to distinguish sleep vs. wakefulness since the earliest EEG studies of sleep (1). Several neural circuits have been implicated in the synchronization and desynchronization of cortical activity that distinguish non-rapid eye movement sleep (NREM) from wakefulness and rapid eye movement sleep (REM). Input from the basal forebrain (BF), likely from both cholinergic and noncholinergic neurons, is critical for the desynchronized EEG characteristic of wakefulness and REM (2, 3). Synchronization of the EEG during NREM depends on thalamic as well as intrinsic cortical oscillators (4).The firing rate of cortical neurons has generally been reported to be reduced during NREM relative to wakefulness and REM (5, 6). A few studies have reported cortical neurons with the opposite pattern. For example, 4 of 177 neurons in the monkey orbitofrontal cortex increased their firing rates during NREM (7). In the cat parietal cortex, 25% of neurons discharged in phase with NREM slow waves during up states but ceased firing during quiet wakefulness (8).Using Fos immunohistochemistry as a marker of cellular activity, we described a population of cortical GABAergic interneurons that are activated during sleep in three species (9, 10). These neurons express neuronal nitric oxide synthase (nNOS) and thus likely release nitric oxide (NO) as well as GABA (11). The percentage of activated cortical nNOS neurons was proportional to NREM δ energy (NRDE), the product of NREM time and NREM EEG δ power. Because NREM time and δ power increase in response to prolonged wakefulness through a regulated process referred to as sleep homeostasis, NRDE is an electrophysiological marker of homeostatic sleep "drive." Consequently, activation of cortical nNOS neurons during sleep seems to be related to the sleep need that accrues during wakefulness.Cortical nNOS neurons receive cholinergic (12), monoamin...

Self-reported gout is common among patients with CKD and lower GFR is strongly associated with gout. Pharmacological management of gout in patients with CKD is suboptimal. Prospective follow-up will show whether gout and hyperuricaemia increase the risk of CKD progression and cardiovascular events in the GCKD study.

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The pigeon is a standard animal in comparative psychology and is frequently used to investigate visuocognitive functions. Nonetheless, the strategies that pigeons use to discriminate complex visual stimuli remain a difficult area of study. In search of a reliable method to identify features that control the discrimination behaviour, pecking location was tracked using touch screen technology in a people-absent/people-present discrimination task. The correct stimuli contained human figures anywhere on the picture, but the birds were not required to peck on that part. However, the stimuli were designed in a way that only the human figures contained distinguishing information. All pigeons focused their pecks on a subarea of the distinctive human figures, namely the heads. Removal of the heads significantly impaired performance, while removal of other distinctive parts did not. Thus, peck tracking reveals the location within a complex visual stimulus that controls discrimination behaviour, and might be a valuable tool to reveal the strategies pigeons apply in visual discrimination tasks.

Genetic variation is a primary determinant of phenotypic diversity. In laboratory mice, genetic variation can be a serious experimental confounder, and thus minimized through inbreeding. However, generalizations of results obtained with inbred strains must be made with caution, especially when working with complex phenotypes and disease models. Here we compared behavioral characteristics of C57Bl/6—the strain most widely used in biomedical research—with those of 129S4. In contrast to 129S4, C57Bl/6 demonstrated high within-strain and intra-litter behavioral hyperactivity. Although high consistency would be advantageous, the majority of disease models and transgenic tools are in C57Bl/6. We recently established six Cre driver lines and two Cre effector lines in 129S4. To augment this collection, we genetically engineered a Cre line to study astrocytes in 129S4. It was validated with two Cre effector lines: calcium indicator gCaMP5g-tdTomato and RiboTag—a tool widely used to study cell type-specific translatomes. These reporters are in different genomic loci, and in both the Cre was functional and astrocyte-specific. We found that calcium signals lasted longer and had a higher amplitude in cortical compared to hippocampal astrocytes, genes linked to a single neurodegenerative disease have highly divergent expression patterns, and that ribosome proteins are non-uniformly expressed across brain regions and cell types.