Widespread psychoactive pollutant augments daytime restfulness and disrupts diurnal activity rhythms in fish

Pharmaceutical pollution is a major driver of global change, with the capacity to alter key behavioural and physiological traits in exposed animals. Antidepressants are among the most commonly detected pharmaceuti-cals in the environment. Despite well-documented pharmacological effects of antidepressants on sleep in humans and other vertebrates, very little is known about their ecologically relevant impacts as pollutants on non-target wildlife. Accordingly, we investigated the effects of acute 3-day exposure of eastern mosquitofish (Gambusia holbrooki) to field-realistic levels (nominal concentrations: 30 and 300 ng/L) of the widespread psychoactive pollutant, fluoxetine, on diurnal activity patterns and restfulness, as indicators of disruptions to sleep. We show that exposure to fluoxetine disrupted diel activity patterns, which was driven by augmentation of daytime inactivity. Specifically, unexposed control fish were markedly diurnal, swimming farther during the day and exhibiting longer periods and more bouts of inactivity at night. However, in fluoxetine-exposed fish, this natural diel rhythm was eroded, with no differences in activity or restfulness observed between the day and night. As a misalignment in the circadian rhythm has been shown to adversely affect fecundity and lifespan in animals, our findings reveal a potentially serious threat to the survival and reproductive success of pollutant-exposed wildlife

Spectral Properties of Brain Activity Under Two Anesthetics and Their Potential for Inducing Natural Sleep in Birds

Both mammals and birds exhibit two sleep states, slow wave sleep (SWS) and rapid eye movement (REM) sleep. Studying certain aspects of sleep-related electrophysiology in freely behaving animals can present numerous methodological constraints, particularly when even fine body movements interfere with electrophysiological signals. Interestingly, under light general anesthesia, mammals and birds also exhibit slow waves similar to those observed during natural SWS. For these reasons, slow waves occurring under general anesthesia are commonly used in the investigation of sleep-related neurophysiology. However, how spectral properties of slow waves induced by anesthesia correspond to those occurring during natural SWS in birds has yet to be investigated systematically. In this study, we systematically analyzed spectral properties of electroencephalographic (EEG) patterns of pigeons (Columba livia) occurring under two commonly used anesthetics, isoflurane and urethane. These data were compared with EEG patterns during natural sleep. Slow waves occurring during spontaneous SWS, and those induced with isoflurane and urethane all showed greatest absolute power in the slowest frequencies (<3 Hz). Isoflurane and urethane-induced slow waves had near-identical power spectra, and both had higher mean power than that observed during SWS for all frequencies examined (0–25 Hz). Interestingly, burst suppression EEG activity observed under deeper planes of isoflurane anesthesia could occur bihemispherically or unihemispherically. Electrophysiological patterns while under isoflurane and urethane share phenomenological and spectral similarities to those occurring during SWS, notably the generation of high amplitude, slow waves, and peak low-frequency power. These results build upon other studies which suggest that some anesthetics exert their effects by acting on natural sleep pathways. As such, anesthesia-induced slow waves appear to provide an acceptable model for researchers interested in investigating sleep-related slow waves utilizing electrophysiological methods not suitable for use in freely behaving birds

Ostriches Sleep like Platypuses

Mammals and birds engage in two distinct states of sleep, slow wave sleep (SWS) and rapid eye movement (REM) sleep. SWS is characterized by slow, high amplitude brain waves, while REM sleep is characterized by fast, low amplitude waves, known as activation, occurring with rapid eye movements and reduced muscle tone. However, monotremes (platypuses and echidnas), the most basal (or ‘ancient’) group of living mammals, show only a single sleep state that combines elements of SWS and REM sleep, suggesting that these states became temporally segregated in the common ancestor to marsupial and eutherian mammals. Whether sleep in basal birds resembles that of monotremes or other mammals and birds is unknown. Here, we provide the first description of brain activity during sleep in ostriches (Struthio camelus), a member of the most basal group of living birds. We found that the brain activity of sleeping ostriches is unique. Episodes of REM sleep were delineated by rapid eye movements, reduced muscle tone, and head movements, similar to those observed in other birds and mammals engaged in REM sleep; however, during REM sleep in ostriches, forebrain activity would flip between REM sleep-like activation and SWS-like slow waves, the latter reminiscent of sleep in the platypus. Moreover, the amount of REM sleep in ostriches is greater than in any other bird, just as in platypuses, which have more REM sleep than other mammals. These findings reveal a recurring sequence of steps in the evolution of sleep in which SWS and REM sleep arose from a single heterogeneous state that became temporally segregated into two distinct states. This common trajectory suggests that forebrain activation during REM sleep is an evolutionarily new feature, presumably involved in performing new sleep functions not found in more basal animals

Validation of ‘Somnivore’, a Machine Learning Algorithm for Automated Scoring and Analysis of Polysomnography Data

Manual scoring of polysomnography data is labor-intensive and time-consuming, and most existing software does not account for subjective differences and user variability. Therefore, we evaluated a supervised machine learning algorithm, SomnivoreTM, for automated wake–sleep stage classification. We designed an algorithm that extracts features from various input channels, following a brief session of manual scoring, and provides automated wake-sleep stage classification for each recording. For algorithm validation, polysomnography data was obtained from independent laboratories, and include normal, cognitively-impaired, and alcohol-treated human subjects (total n = 52), narcoleptic mice and drug-treated rats (total n = 56), and pigeons (n = 5). Training and testing sets for validation were previously scored manually by 1–2 trained sleep technologists from each laboratory. F-measure was used to assess precision and sensitivity for statistical analysis of classifier output and human scorer agreement. The algorithm gave high concordance with manual visual scoring across all human data (wake 0.91 ± 0.01; N1 0.57 ± 0.01; N2 0.81 ± 0.01; N3 0.86 ± 0.01; REM 0.87 ± 0.01), which was comparable to manual inter-scorer agreement on all stages. Similarly, high concordance was observed across all rodent (wake 0.95 ± 0.01; NREM 0.94 ± 0.01; REM 0.91 ± 0.01) and pigeon (wake 0.96 ± 0.006; NREM 0.97 ± 0.01; REM 0.86 ± 0.02) data. Effects of classifier learning from single signal inputs, simple stage reclassification, automated removal of transition epochs, and training set size were also examined. In summary, we have developed a polysomnography analysis program for automated sleep-stage classification of data from diverse species. Somnivore enables flexible, accurate, and high-throughput analysis of experimental and clinical sleep studies

Energetic costs and benefits of sleep.

Energy derived from food is a precious resource to animals. Those finite calories are often well-earned through exhaustive foraging effort, which can dominate waking hours, to support physiological processes (e.g. body maintenance and growth) and ecological necessities (e.g. predator avoidance and courting) that are pertinent to the production of progeny. So, it is unsurprising to find that animals have evolved strategies to guard against the gratuitous waste of hard-won caloric energy. Yet, it remains surprising to find such diversity, and elegant creativity, in those solutions. Brief examples of energy-saving innovation could include the very shape of animals and how they move, from streamlined swimming sharks to skyward-soaring seabirds; or the evolutionary appearance of various states of dormancy, such as endothermic animals sacrificing high body temperature through modest (torpor) or severe (hibernation) curtailments to metabolic heat production. Another reversibly dormant state with energetic benefits is sleep

Sleep architecture and regulation of male dusky antechinus, an Australian marsupial

Study Objectives In this study, we (1) describe sleep behavior and architecture, and (2) explore how sleep is regulated in dusky antechinus (Antechinus swainsonii), a small insectivorous marsupial. Our aim is to provide the first investigation into sleep homeostasis in a marsupial. Methods Wild-caught male dusky antechinus (n = 4) were individually housed in large indoor cages under a natural photoperiod of 10.5 h light/13.5 h dark. Continuous recordings of EEG, EMG, and tri-axial accelerometry were performed under baseline conditions and following 4-h of extended wakefulness. Results Antechinus engage in SWS and REM sleep. Some aspects of these states are mammal-like, including a high amount (23%) of REM sleep, but other features are reminiscent of birds, notably, hundreds of short sleep episodes (SWS mean: 34 s; REM sleep: 10 s). Antechinus are cathemeral and sleep equally during the night and day. Immediately after the sleep deprivation ended, the animals engaged in more SWS, longer SWS episodes, and greater SWS SWA. The animals did not recover lost REM sleep. Conclusions Sleep architecture in dusky antechinus was broadly similar to that observed in eutherian and marsupial mammals, but with interesting peculiarities. We also provided the first evidence of SWS homeostasis in a marsupial mammal.ISSN:1550-9109ISSN:0161-810

Data from: Artificial light at night desynchronises strictly seasonal reproduction in a wild mammal

Change in day length is an important cue for reproductive activation in seasonally breeding animals to ensure that the timing of greatest maternal investment (e.g. lactation in mammals) coincides with favourable environmental conditions (e.g. peak productivity). However, artificial light at night has the potential to interfere with the perception of such natural cues. Following a 5-year study on two populations of wild marsupial mammals exposed to different night-time levels of anthropogenic light, we show that light pollution in urban environments masks seasonal changes in ambient light cues, suppressing melatonin levels and delaying births in the tammar wallaby. These results highlight a previously unappreciated relationship linking artificial light at night with induced changes in mammalian reproductive physiology, and the potential for larger-scale impacts at the population level

Supplementary materials to BEH 3776

   Figure A1. Tool-use apparatus. (a) Tool-use apparatus seen from the side with stick tool inserted between the transparent walls. (b) Apparatus seen from above next to the stick tool and digitally inserted ruler. Table A1. Ethogram of behaviours displayed towards the tool use set-up and average occurrences of the behaviours observed during the study (N = 11 birds; mean ± standard deviation). Tool use as a behaviour was not included in the ethogram because it was only displayed once by a single bird. Table A2. Total amount of time (min) each bird was presented the tool use apparatus. Table A3. Number of times each bird pulled the stick to acquire food. Video 1. Australian magpies pulling a stick to acquire food. Video 2. Australian magpie using a stick tool to extract food.</p