Editorial: Local Aspects of Sleep and Wakefulness

No abstract availabl

Direct emergence of the dorsospinal artery from the aorta and spinal cord blood supply: Case reports and literature review

Introduction: Direct emergence of a dorsospinal artery from the aorta is a rare anatomic variant, of which a total of seven cases have been reported. This report offers an additional angiographic observation and reviews the literature. Methods: Two observations of common intercostal trunks documented during spinal angiography are described. Results: In the first observation, the common intercostal trunk provided complete blood supply to two adjacent vertebral levels (T11 and T12). In other words, the trunk included an intercostal branch and a dorsospinal branch for each level. In the second observation, the common intercostal trunk provided an intercostal branch for each level (T9 and T10), but only one dorsospinal branch (T10). An isolated dorsospinal artery (DA) originated separately from the aorta at the T9 level, and provided a significant contribution to the anterior spinal axis. Conclusion: The two reported cases illustrate the concept of "complete” versus "incomplete” common intercostal trunks. In instances where an incomplete trunk is documented, a separate DA originating directly from the aorta must be looked for. A review of the literature indicates a tendency for isolated DAs to participate in the blood supply to the spinal cor

Local and Widespread Slow Waves in Stable NREM Sleep: Evidence for Distinct Regulation Mechanisms

Previous work showed that two types of slow waves are temporally dissociated during the transition to sleep: widespread, large and steep slow waves predominate early in the falling asleep period (type I), while smaller, more circumscribed slow waves become more prevalent later (type II). Here, we studied the possible occurrence of these two types of slow waves in stable non-REM (NREM) sleep and explored potential differences in their regulation. A heuristic approach based on slow wave synchronization efficiency was developed and applied to high-density electroencephalographic (EEG) recordings collected during consolidated NREM sleep to identify the potential type I and type II slow waves. Slow waves with characteristics compatible with those previously described for type I and type II were identified in stable NREM sleep. Importantly, these slow waves underwent opposite changes across the night, with only type II slow waves displaying a clear homeostatic regulation. In addition, we showed that the occurrence of type I slow waves was often followed by larger type II slow waves, whereas the occurrence of type II slow waves was usually followed by smaller type I waves. Finally, type II slow waves were associated with a relative increase in spindle activity, while type I slow waves triggered periods of high-frequency activity. Our results provide evidence for the existence of two distinct slow wave synchronization processes that underlie two different types of slow waves. These slow waves may have different functional roles and mark partially distinct “micro-states” of the sleeping brain

EEG functional connectivity metrics wPLI and wSMI account for distinct types of brain functional interactions

Abstract: The weighted Phase Lag Index (wPLI) and the weighted Symbolic Mutual Information (wSMI) represent two robust and widely used methods for MEG/EEG functional connectivity estimation. Interestingly, both methods have been shown to detect relative alterations of brain functional connectivity in conditions associated with changes in the level of consciousness, such as following severe brain injury or under anaesthesia. Despite these promising findings, it was unclear whether wPLI and wSMI may account for distinct or similar types of functional interactions. Using simulated high-density (hd-)EEG data, we demonstrate that, while wPLI has high sensitivity for couplings presenting a mixture of linear and nonlinear interdependencies, only wSMI can detect purely nonlinear interaction dynamics. Moreover, we evaluated the potential impact of these differences on real experimental data by computing wPLI and wSMI connectivity in hd-EEG recordings of 12 healthy adults during wakefulness and deep (N3-)sleep, characterised by different levels of consciousness. In line with the simulation-based findings, this analysis revealed that both methods have different sensitivity for changes in brain connectivity across the two vigilance states. Our results indicate that the conjoint use of wPLI and wSMI may represent a powerful tool to study the functional bases of consciousness in physiological and pathological conditions

Violence in sleep

Although generally considered as mutually exclusive, violence and sleep can coexist. Violence related to the sleep period is probably more frequent than generally assumed and can be observed in various conditions including parasomnias (such as arousal disorders and rapid eye movement sleep behaviour disorder), epilepsy (in particular nocturnal frontal lobe epilepsy) and psychiatric diseases (including delirium and dissociative states). Important advances in the fields of genetics, neuroimaging and behavioural neurology have expanded the understanding of the mechanisms underlying violence and its particular relation to sleep. The present review outlines the different sleep disorders associated with violence and aims at providing information on diagnosis, therapy and forensic issues. It also discusses current pathophysiological models, establishing a link between sleep-related violence and violence observed in other setting

The rhythm of the night: patterns of~activity of the European wildcat in the Italian peninsula

The European wildcat is a threatened carnivore, whose ecology is still scarcely studied, especially in Mediterranean areas. In this study, we estimated activity rhythm patterns of this felid, by means of camera-trapping at three spatial scales: (i) whole country (Italy); (ii) biogeographical areas; (iii) latitudinal zones. The activity rhythms patterns were also calculated according to temporal scales: (1) warm semester; (2) cold semester and (3) seasonal scales. Lastly, we also tested whether the effect of moon phases affected the wildcat activity. We conducted the analysis on a total of 975 independent events collected in 2009-2021, from 285 locations, in 65,800 camera days. We showed that the wildcat in Italy exhibits a > 70% nocturnal behaviour, with 20% of diurnal activity, at all spatial scales, and throughout the whole year, with peaks at 10.00 p.m. and 04.00 a.m. We observed a high overlap of wildcat activity rhythms between different biogeographical and latitudinal zones. The wildcat was mainly active on the darkest nights, reducing its activity in bright moonlight nights. Diurnal activity was greater in the warm months and decreased with the distance from shrubs and woodlands, most likely according to activity rhythms of its main prey, water presence in summer, the care of offspring and the availability of shelter sites. Conversely, the distance to paved roads seems to have no significant effects on diurnal activity, suggesting that, in presence of natural shelters, the wildcat probably may tolerate these infrastructures. We suggested limited plasticity in activity rhythm patterns of the wildcat, emphasizing the importance of dark hours for this species

The neural correlates of dreaming.

Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density electroencephalography, we contrasted the presence and absence of dreaming in NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with local decreases in low-frequency activity in posterior cortical regions. High-frequency activity in these regions correlated with specific dream contents. Monitoring this posterior 'hot zone' in real time predicted whether an individual reported dreaming or the absence of dream experiences during NREM sleep, suggesting that it may constitute a core correlate of conscious experiences in sleep