Journal of Comparative Physiology A-Neuroethology Sensory Neural and Behavioral Physiology最新文献

The natural lighting conditions vary depending on latitude, niche, and time of day, and animals are evolutionarily adapted to them. Artificial lighting, along with global warming, drives population ranges toward high latitudes, which creates fast-changing environments for the biota. The American cockroach Periplaneta americana L. is a synanthropic species with a nocturnal lifestyle, rarely exposed to light. Three-month-long exposure to constant light or constant darkness compared to the control 12:12 h day and night cycle, causes behavioral changes explained by two main factors: adaptation of the visual system and circadian rhythm disruption. State of complete immobility, an indicator of the inactive phase of a 24 h rhythm, appeared in groups kept under constant light regimes and tested in the dark, as well as in those subjected to experimental lighting with low-intensity green light. Exposure to such light caused different behavioral changes in groups kept under different light regimes, reflecting the cockroaches' internal levels of arousal, stress, and light adaptation of their photoreceptor organs. Thus, altered lighting conditions impose significant challenges on different aspects of insect physiology and behavior.

As the Arctic warms and becomes more accessible to human activities and associated noise sources, it is important to understand the auditory capabilities of ice-associated marine mammals that rely on sound. In this study, the in-air hearing of one adult bearded seal (Erignathus barbatus) was measured in ambient outdoor conditions using psychophysical methods. 50% detection thresholds were measured for 10 frequencies (0.04-51.2 kHz) that extend across the subject's hearing range. For low to mid frequencies (0.04-12.8 kHz), thresholds were constrained, or masked, by ambient noise. Thresholds obtained at higher frequencies (25.6-51.2 kHz) were sufficiently elevated above background noise to provide absolute measures of hearing sensitivity. These measurements reveal that the high-frequency roll-off for bearded seals is in alignment with available auditory data for related species despite more than 11 million years of evolutionary isolation. Further, the data collected at low and mid frequencies enable an unconventional estimation of critical ratios, which can be applied in masking models. Collectively, these findings for bearded seals listening for airborne sounds highlight auditory similarities within the northern clade of phocid Carnivores and improve predictions of potential noise effects for seals in changing Arctic soundscapes.

Species recognition is essential for reproductive isolation and plays a central role in the evolution of mating signals. In acoustically communicating species, temporal features of calls are critical for distinguishing conspecific from heterospecific signals. Anurans rely heavily on the precise timing of pulse trains for mate recognition. Females of Hyla chrysoscelis use the species-specific temporal structure of male advertisement (Adv) calls-specifically pulse rate (PR)-to select mates. For stimuli with the Adv call PR (40-60 pulses/s), females require at least ~ 6-7 pulses to approach a sound source, implicating interval-counting neurons (ICNs) in call recognition. To test this model and further investigate the neural basis of this temporal selectivity, we used behavioral and neurophysiological approaches. We lengthened interpulse intervals (IPIs) in pulse trains either at a single midpoint or in an alternating fashion while holding pulse number and, thus, stimulus energy constant. In phonotaxis assays, females showed sharply reduced responses when even one IPI was lengthened twofold or more, revealing high sensitivity to temporal irregularity. Single-unit in vivo extracellular recordings from the auditory midbrain revealed that ICNs exhibited a progressive decline in activity with increasing IPI length, closely mirroring behavioral trends. In contrast, long-interval neurons (LINs) responded more strongly to temporally irregular stimuli. These results support the hypothesis that ICNs mediate behavioral selectivity for conspecific Adv call temporal patterns, whereas LINs may contribute to processing other call types. Our study directly links a defined neuronal population to natural behavior, underscoring how midbrain temporal computations underlie species-specific recognition in Hyla chrysoscelis.

Most humans have experienced regurgitation and vomiting (emesis) at some point in their lives. These behaviors are also commonly observed throughout the rest of the animal kingdom, serving various functions such as feeding, courtship, defense against predators, and protection from accidental toxin ingestion. Studying these behaviors offers valuable insights into the underlying gut-brain axis and presents opportunities to identify new therapeutic targets. However, detailed mechanistic studies on the molecular, genetic, and neural circuit basis of regurgitative behaviors have been hampered until recently due to the lack of suitable genetic model organisms capable of regurgitation. This review introduces researchers to the mechanisms of regurgitative behaviors, particularly those related to the gut-brain axis. We summarize these behaviors across different taxa, review current knowledge of their underlying mechanisms with a focus on gut-brain connections, and discuss related pathologies. Finally, we present recent findings from Drosophila models of regurgitation and emesis, and outline key questions that still require attention.

Praying mantises often display elaborate camouflage, disappearing into the shapes, textures, and colors around them. But they have largely been thought to be monochromats, unable to perceive the colors they mimic. To examine this, we tested the compound eye spectral sensitivity of three species of praying mantises, each representing unique mimicry strategies: Theopropus elegans, Popa spurca, and Hymenopus coronatus. We quantified mantis spectral sensitivity to light, ranging from 350 to 650 nm wavelength, using electroretinography under both dark and chromatic adaptation. We find distinct spectral sensitivity peaks that suggest the presence of multiple photoreceptor types or varying expressions of visual pigments across the species studied. T. elegans and P. spurca exhibited potential trichromatic vision, with primary sensitivity peaks in green (515-525 nm), and secondary and tertiary peaks in ultraviolet (350-360 nm) and blue (441 nm and 416 nm). Conversely, H. coronatus displayed a simpler dichromatic pattern. This suggests praying mantises have the capacity for color vision, likely adapted to enhance camouflage and predatory efficiency in their environments.

Caterpillars (larval Lepidoptera) are one of the most ecologically and evolutionarily significant taxa on Earth. As both feeders and food, they shape the dynamics of enumerate ecosystems on land. Key to this prominent role in nature is the sensory systems that inform, guide, and trigger their behaviour. Gaining an understanding of caterpillar sensory ecology therefore promises to reveal fundamental insights into the broader principles of ecology and evolution, conservation and management, within and beyond the Lepidoptera. To facilitate such an understanding, here we review the existing literature on the sensory physiology and ecology of all currently recognised sensory modalities in caterpillars, namely vision, hearing, vibration detection, touch, electroreception, chemoreception, hygroreception, thermoreception, and graviception. In each of these sensory modalities, we also explore the current evidence surrounding the threat of anthropogenic sensory pollution. Taken together, this review reveals the great depth and breadth of research into caterpillar sensory ecology, making clear the value of caterpillars to neuroethology, but also of neuroethology to caterpillars. However, many of the attributes that caterpillars bring to neuroethological research are yet to be taken advantage of. For example, there is currently a lack of comparative sensory system studies on caterpillars, utilising their ecological diversity and existing phylogenetic data. We also highlight many considerable knowledge gaps, most pertinently, the need to identify the sensors responsible for each sensory modality in caterpillars, and to characterise the potential effects of sensory pollution across all of these modalities.

The Lepidoptera, butterflies and moths, display an astonishing diversity of spatial orientation strategies essential for survival, reproduction, and ecological success. These spatial orientation strategies range from basic taxes to light, wind, gravity, and chemical cues, to more advanced strategies such as straight-line dispersal, multigenerational migration across continents, and complex trap-lining foraging involving long-term spatial memory. These orientation behaviours are tightly integrated with the ecological roles of lepidopterans as pollinators, prey, and bioindicators, and are supported by a flexible neuronal network. Of special interest for successful orientation are higher-order integration centres like the mushroom bodies (centres for learning and memory) and the central complex (the centre for spatial orientation and locomotion). These centres support cue integration, compass orientation, memory, and directional decision-making. However, anthropogenic stressors, including habitat fragmentation, light pollution, pesticides, and electromagnetic noise, threaten both the environmental cues and the neural systems facilitating lepidopteran navigation, with potential cascading effects on biodiversity and ecosystem health. By combining insights from behavioural ecology, neurobiology, and conservation, we aim to provide a comprehensive overview of the challenges and adaptations that shape the navigational toolkit of lepidopterans, underlining their significance as animal models for studying spatial orientation in a changing world.

Many insects are formidable navigators illustrated by homing behavior in bees and ants or regular seasonal migrations in butterflies, moths, and others. For spatial orientation, many insects rely on celestial cues, in particular the position of the sun or the polarization pattern of the blue sky generated by the sun. In all species studied celestial polarization is perceived by photoreceptors in a highly specialized dorsal rim area of the eye. Studies in various insects showed that the central complex utilizes these and other sensory inputs to create an internal compass-like representation of external space for vector navigation. Cockroaches, likewise, rely on visual and antennal input for navigational decisions mediated by the central complex. To explore the possible contribution of sky compass signals, we have characterized the responsiveness of neurons of the optic lobe and central complex of the Madeira cockroach Rhyparobia maderae to the angle of polarized light and the azimuth of unpolarized light spots representing the sun or the chromatic gradient of the sky. Strong responses to polarization angle and to changing polarization angle were found in several cell types connecting both optic lobes. Responses to sky compass signals in neurons of the central complex were less pronounced, but were significant in several cell types corresponding to neurons encoding sun compass signals in other species. Although the Madeira cockroach is a nocturnal scavenger and the existence of a specialized dorsal eye region has not been established, sky compass signals likely play a substantial role in behavioral decisions.

Atlantic salmon (Salmo salar) move from fresh- to seawater environments following a seasonally timed preparative transition called smoltification, which takes place under photoperiodic control in the freshwater environment. In masu salmon (Oncorhynchus masou), coordination of photoperiodic sexual maturation is proposed to involve in a fish-specific circumventricular organ, the saccus vasculosus (SV), through its intrinsic opsin-based light sensitivity, thyrotrophin secretion and modulation of deiodinase activity (TSH-DIO cascade). The saccus vasculosus is a highly vascularized structure located on the ventral side of the hypothalamus and its interface between the blood and cerebrospinal fluid also hints at a role in ionic balance of the cerebrospinal fluid (CSF). Both the potential photoperiodic and ionic functions of the SV led us to perform transcriptome analysis of the SV in smoltification in Atlantic salmon. Specifically, we compared transcriptomes of SVs collected from freshwater fish following exposure to an 8-week stimulated winter photoperiod followed by 8-week simulated summer photoperiod, or a 16-week simulated winter photoperiod control and from both photoperiod treatments after 24 h exposure to seawater. Our data show that SV response to seawater exposure is highly dependent on photoperiodic history and identifies ependymin as a major secretory output of the SV, consistent with a role in control of CSF composition. Conversely, we could not detect crucial elements of the opsin-TSH-DIO cascade suggesting that the photoperiodic history-dependence of the SV to seawater exposure is unlikely to stem from SV-intrinsic responses to photoperiod.