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Olfaction is a critical sensory modality for invertebrates, and it mediates a wide range of behaviors and physiological processes. Like most living organisms, insects live in rhythmic environments: the succession of nights and days is accompanied by cyclic variations in light intensity and temperature, as well as in the availability of resources and the activity of predators. Responding to olfactory cues in the proper temporal context is thus highly adaptive and allows for the efficient allocation of energy resources. Given the agricultural or epidemiological importance of some insect species, understanding olfactory rhythms is critical for the development of effective control strategies. Although the vinegar fly Drosophila melanogaster has been a classical model for the study of olfaction and circadian rhythms, recent studies focusing on non-model species have expanded our understanding of insect olfactory rhythms. Additionally, recent evidence revealing receptor co-expression by sensory neurons has brought about an ongoing paradigm shift in our understanding of insect olfaction, making it timely to review the state of our knowledge on olfactory rhythms and identify critical future directions for the field. In this Review, we discuss the multiple biological scales at which insect olfactory rhythms are being analyzed, and identify outstanding questions., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

The physiological diversity of inhibitory neurons provides ample opportunity to influence a wide range of computational roles through their varied activity patterns, especially via feedback loops. In the avian auditory brain stem, inhibition originates primarily from the superior olivary nucleus (SON), and so it is critical to understand the intrinsic physiological properties and processing capabilities of these neurons. Neurons in the SON receive ascending input via the cochlear nuclei: directly from the intensity-coding cochlear nucleus angularis (NA) and indirectly via the interaural timing nucleus laminaris (NL), which itself receives input from cochlear nucleus magnocellularis (NM). Two distinct populations of SON neurons provide inhibitory feedback either to ipsilateral NA, NL, and the timing cochlear nucleus NM or to the contralateral SON. To determine whether these populations correspond to distinct response types, we investigated their electrophysiology in brain stem slices, using patch-clamp electrophysiology. We identified three phenotypes: single-spiking, chattering tonic, and regular tonic neurons. The two tonic phenotypes displayed distinct firing patterns and different membrane properties. Fluctuating "noisy" currents used to probe the capability of SON neurons to encode temporal features showed that each phenotype differed in sensitivity to temporally modulated input. By using cell fills and anatomical reconstructions, we could correlate the firing phenotypes with their axonal projection patterns. We found that SON axons exited via three fiber tracts, with each tract composed of specific phenotypes. These results provide a basis for understanding the role of specific inhibitory cell types in auditory function and elucidate the organization of the SON outputs. NEW & NOTEWORTHY Inhibitory inputs for the avian brain stem originate primarily from the superior olivary nucleus (SON). We describe three intrinsic phenotypes of SON neurons and show how they differ in their temporal processing and projection patterns. We propose that the two types of tonic firing neurons (including one novel type) and the single-spiking neurons in SON comprise separate feedback circuits that may differentially influence the auditory information flowing via the cochlear nuclei and nucleus laminaris.

Background: Stereotaxic surgery is a cornerstone in brain research for the precise positioning of electrodes and probes, but its application is limited to species with available brain atlases and tailored stereotaxic frames. Addressing this limitation, we introduce an alternative technique for small animal brain surgery that requires neither an aligned brain atlas nor a stereotaxic frame., New Method: The new method requires an ex-vivo high-contrast MRI brain scan of one specimen and access to a micro-CT scanner. The process involves attaching miniature markers to the skull, followed by CT scanning of the head. Subsequently, MRI and CT images are co-registered using standard image processing software and the targets for brain recordings are marked in the MRI image. During surgery, the animal's head is stabilized in any convenient orientation, and the probe's 3D position and angle are tracked using a multi-camera system. We have developed a software that utilizes the on-skull markers as fiducial points to align the CT/MRI 3D model with the surgical positioning system, and in turn instructs the surgeon how to move the probe to reach the targets within the brain., Results: Our technique allows the execution of insertion tracks connecting two points in the brain. We successfully applied this method for neuropixels probe positioning in owls, quails, and mice, demonstrating its versatility., Comparison With Existing Methods: We present an alternative to traditional stereotaxic brain surgeries that does not require established stereotaxic tools. Thus, this method is especially of advantage for research in non-standard and novel animal models., Competing Interests: Declaration of Competing Interest None, (Copyright © 2024 Elsevier B.V. All rights reserved.)

The meninges and associated vasculature (MAV) play a crucial role in maintaining cerebral integrity and homeostasis. Recent advances in transcriptomic analysis have illuminated the significance of the MAV in understanding the complex physiological interactions at the interface between the skull and the brain after exposure to mechanical stress. To investigate how physiological responses may confer resilience against repetitive mechanical stress, we performed the first transcriptomic analysis of avian MAV tissues using the Downy Woodpecker (Dryobates pubescens) and Tufted Titmouse (Baeolophus bicolor) as the comparison species. Our findings reveal divergences in gene expression profiles related to immune response, cellular stress management, and protein translation machinery. The male woodpeckers exhibit a tailored immune modulation strategy that potentially dampens neuroinflammation while preserving protective immunity. Overrepresented genes involved in cellular stress responses suggest enhanced mechanisms for mitigating damage and promoting repair. Additionally, the enrichment of translation-associated pathways hints at increased capacity for protein turnover and cellular remodeling vital for recovery. Our study not only fills a critical gap in avian neurobiology but also lays the groundwork for research in comparative neuroprotection., (© 2024 American Association for Anatomy.)

One crucial interaction for the health of fish communities in coral reefs is performed by cleaner fish by removing ectoparasites from the body of other fish, so-called clients. Studying the underlying mechanisms of this behaviour is essential to understanding how species react to social stimuli and defining the drivers of mutualistic social behaviour. Here, we pinpoint the neural molecular mechanisms in the cleaning behaviour of Labroides dimidiatus in the wild through an in situ interaction experiment at a coral reef in New Caledonia. Five cleaners and clients ( Abudefduf saxatilis ) were placed into underwater aquaria to interact, while five were not presented with a client. The brain transcriptomes revealed 233 differentially expressed genes in cleaners that were interacting with a client. Among these genes, grin2d , npy , slc6a3 and immediate early genes (IEGs; fosb and fosl1 ) were related to learning and memory, glutamate and dopamine pathways, which confirm molecular pathways observed in laboratory studies. However, a new potential mechanism was found with npy (neuropeptide Y) as a driver of feeding behaviour. These results show the role of neurotransmitters and IEGs in mutualistic social behaviour, unveiling the mechanism behind the feeding stimulus that leads the cleaner fish to establish mutualistic interactions in coral reefs.

The present study aims to investigate whether begging calls elicit specific auditory responses in non-parenting birds, whether these responses are influenced by the hormonal status of the bird, and whether they reflect biparental care for offspring in the European starling ( Sturnus vulgaris ). An fMRI experiment was conducted to expose non-parenting male and female European starlings to recordings of conspecific nestling begging calls during both artificially induced breeding and non-breeding seasons. This response was compared with their reaction to conspecific individual warbling song motifs and artificial pure tones, serving as social species-specific and artificial control stimuli, respectively. Our findings reveal that begging calls evoke a response in non-parenting male and female starlings, with significantly higher responsiveness observed in the right Field L and the Caudomedial Nidopallium (NCM), regardless of season or sex. Moreover, a significant seasonal variation in auditory brain responses was elicited in both sexes exclusively by begging calls, not by the applied control stimuli, within a ventral midsagittal region of NCM. This heightened response to begging calls, even in non-parenting birds, in the right primary auditory system (Field L), and the photoperiod induced hormonal neuromodulation of auditory responses to offspring's begging calls in the secondary auditory system (NCM), bears resemblance to mammalian responses to hunger calls. This suggests a convergent evolution aimed at facilitating swift adult responses to such calls crucial for offspring survival., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Vidas-Guscic, Jonckers, Van Audekerke, Orije, Hamaide, Majumdar, Henry, Hausberger, Verhoye and Van der Linden.)

In the natural world, animals make decisions on an ongoing basis, continuously selecting which action to undertake next. In the lab, however, the neural bases of decision processes have mostly been studied using artificial trial structures. New experimental tools based on the genetic toolkit of model organisms now make it experimentally feasible to monitor and manipulate neural activity in small subsets of neurons during naturalistic behaviors. We thus propose a new approach to investigating decision processes, termed reverse neuroethology. In this approach, experimenters select animal models based on experimental accessibility and then utilize cutting-edge tools such as connectomes and genetically encoded reagents to analyze the flow of information through an animal's nervous system during naturalistic choice behaviors. We describe how the reverse neuroethology strategy has been applied to understand the neural underpinnings of innate, rapid decision making, with a focus on defensive behavioral choices in the vinegar fly Drosophila melanogaster .

Every species' brain, body and behavior is shaped by the contingencies of their evolutionary history; these exert pressures that change their developmental trajectories. There is, however, another set of contingencies that shape us and other animals: those that occur during a lifetime. In this perspective piece, we show how these two histories are intertwined by focusing on the individual. We suggest that organisms--their brains and behaviors--are not solely the developmental products of genes and neural circuitry but individual centers of action unfolding in time. To unpack this idea, we first emphasize the importance of variation and the central role of the individual in biology. We then go over "errors in time" that we often make when comparing development across species. Next, we reveal how an individual's development is a process rather than a product by presenting a set of case studies. These show developmental trajectories as emerging in the contexts of the "the actual now" and "the presence of the past". Our consideration reveals that individuals are slippery-they are never static; they are a set of on-going, creative activities. In light of this, it seems that taking individual development seriously is essential if we aspire to make meaningful comparisons of neural circuits and behavior within and across species., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This commentary critiques Mougenot and Matheson's proposal to integrate embodied cognition with mechanistic explanations in cognitive neuroscience. We suggest more promising directions for embodied cognitive neuroscience, focusing on neuroethological research and evolutionary studies of nervous systems. These approaches, compatible with wide mechanistic explanations, offer a robust path forward by examining central nervous system function within whole organisms in their environments.

Studying animal social systems requires understanding variations in contact and interaction, influenced by factors like environmental conditions, resource availability, and predation risk. Traditional observational methods have limitations, but advancements in sensor technologies and data analytics provide new opportunities. We developed a wireless wearable sensor system, "Juxta," with features such as modular battery packs and a smartphone app for data collection. A pilot study on free-living prairie voles ( Microtus ochrogaster ), a species with complex social behavior, demonstrated Juxta's potential for studying social networks and behavior. We propose a framework for merging temporal, spatial, and event-driven data, which can help explore complex social dynamics across species and environments.

The Food Finding Test (FFT) olfactory paradigm without overnight food deprivation examined olfaction in aged (16-months-old) animals. Ethograms of three goal-directed behaviors towards hidden food (sniffing, finding and eating) elicited in male and female 3xTg-AD mice for Alzheimer's disease (AD) and their age-matched C57BL/6 wild-type counterparts with normal aging were meticulously analyzed with the support of video recordings. The new FFT protocol elicited longer ethograms than previously reported with the standard deprivation protocol. However, it was sensitive when identifying genotype- and sex-dependent olfactory signatures for the temporal patterns of slow sniffing, finding, and eating in AD and males, but it had a striking consistency in females. The impact of forced social isolation was studied and it was found to exert sex-dependent modifications of the ethogram, mostly in males. Still, in both sexes, a functional derangement was detected since the internal correlations among the behaviors decreased or were lost under isolated conditions. In conclusion, the new paradigm without overnight deprivation was sensitive to sex (males), genotype (AD), and social context (isolation-dependent changes) in its ethogram and functional correlation. At the translational level, it is a warning about the impact of isolation in the advanced stages of the disease, paying notable attention to the male sex.

For 100 years, the Journal of Comparative Physiology-A has significantly supported research in the field of neuroethology. The celebration of the journal's centennial is a great time point to appreciate the recent progress in neuroethology and to discuss possible avenues of the field. Animal behavior is the main source of inspiration for neuroethologists. This is illustrated by the huge diversity of investigated behaviors and species. To explain behavior at a mechanistic level, neuroethologists combine neuroscientific approaches with sophisticated behavioral analysis. The rapid technological progress in neuroscience makes neuroethology a highly dynamic and exciting field of research. To summarize the recent scientific progress in neuroethology, I went through all abstracts of the last six International Congresses for Neuroethology (ICNs 2010-2022) and categorized them based on the sensory modalities, experimental model species, and research topics. This highlights the diversity of neuroethology and gives us a perspective on the field's scientific future. At the end, I highlight three research topics that may, among others, influence the future of neuroethology. I hope that sharing my roots may inspire other scientists to follow neuroethological approaches., (© 2024. The Author(s).)

The Journal of Comparative Physiology A, also known as JCPA, was founded by Karl von Frisch and Alfred Kühn in 1924, then under its German title Zeitschrift für vergleichende Physiologie. During the 100 years of its history, it became the leading international journal in comparative physiology and its daughter discipline, neuroethology. As such, it had a major impact on the development of these disciplines. In celebration of this achievement and the nearly 10,000 articles that appeared during the last 100 years, this Centennial Issue is published. Its authors reflect on the history of JCPA and the early pioneers, including women scientists, of comparative physiology; share the impact that the Journal had on their careers; discuss the benefit of the enormous taxonomic diversity of model systems used in studies published in JCPA; contrast this philosophy with the strategy of a limited number of standard biomedical model systems; review popular and trending research topics covered in JCPA; and, by interrogating the past, take a peek into the future of neuroethology., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Humans have been trying to understand animal behavior at least since recorded history. Recent rapid development of new technologies has allowed us to make significant progress in understanding the physiological and molecular mechanisms underlying behavior, a key goal of neuroethology. However, there is a tradeoff when studying animal behavior and its underlying biological mechanisms: common behavior protocols in the laboratory are designed to be replicable and controlled, but they often fail to encompass the variability and breadth of natural behavior. This Commentary proposes a framework of 10 key questions that aim to guide researchers in incorporating a rich natural context into their experimental design or in choosing a new animal study system. The 10 questions cover overarching experimental considerations that can provide a template for interspecies comparisons, enable us to develop studies in new model organisms and unlock new experiments in our quest to understand behavior., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

The dorsomedial posterior parietal cortex (dmPPC) is part of a higher-cognition network implicated in elaborate processes underpinning memory formation, recollection, episode reconstruction, and temporal information processing. Neural coding for complex episodic processing is however under-documented. Here, we recorded extracellular neural activities from three male rhesus macaques ( Macaca mulatta ) and revealed a set of neural codes of "neuroethogram" in the primate parietal cortex. Analyzing neural responses in macaque dmPPC to naturalistic videos, we discovered several groups of neurons that are sensitive to different categories of ethogram items, low-level sensory features, and saccadic eye movement. We also discovered that the processing of category and feature information by these neurons is sustained by the accumulation of temporal information over a long timescale of up to 30 s, corroborating its reported long temporal receptive windows. We performed an additional behavioral experiment with additional two male rhesus macaques and found that saccade-related activities could not account for the mixed neuronal responses elicited by the video stimuli. We further observed monkeys' scan paths and gaze consistency are modulated by video content. Taken altogether, these neural findings explain how dmPPC weaves fabrics of ongoing experiences together in real time. The high dimensionality of neural representations should motivate us to shift the focus of attention from pure selectivity neurons to mixed selectivity neurons, especially in increasingly complex naturalistic task designs., (Copyright © 2024 the authors.)

Introduction: Comparative studies of brain anatomy between closely related species have been very useful in demonstrating selective changes in brain structure. Within-species comparisons can be particularly useful for identifying changes in brain structure caused by contrasting environmental selection pressures. Here, we aimed to understand whether differences within and between species in habitat use and foraging behaviour influence brain morphology, on both ecological and evolutionary time scales., Methods: We used as a study model three species of the Elacatinus genus that differ in their habitat-foraging mode. The obligatory cleaning goby Elacatinus evelynae inhabits mainly corals and feeds mostly on ectoparasites removed from larger fish during cleaning interactions. In contrast, the obligatory sponge-dwelling goby Elacatinus chancei inhabits tubular sponges and feeds on microinvertebrates buried in the sponges' tissues. Finally, in the facultatively cleaning goby Elacatinus prochilos, individuals can adopt either phenotype, the cleaning or the sponge-dwelling habitat-foraging mode. By comparing the brains of the facultative goby phenotypes to the brains of the obligatory species we can test whether brain morphology is better predicted by phylogenetic relatedness or the habitat-foraging modes (cleaning × sponge dwelling)., Results: We found that E. prochilos brains from both types (cleaning and sponge dwelling) were highly similar to each other. Their brains were in general more similar to the brains of the most closely related species, E. evelynae (obligatory cleaning species), than to the brains of E. chancei (sponge-dwelling species). In contrast, we found significant brain structure differences between the cleaning species (E. evelynae and E. prochilos) and the sponge-dwelling species (E. chancei). These differences revealed independent changes in functionally correlated brain areas that might be ecologically adaptive. E. evelynae and E. prochilos had a relatively larger visual input processing brain axis and a relatively smaller lateral line input processing brain axis than E. chancei., Conclusion: The similar brain morphology of the two types of E. prochilos corroborates other studies showing that individuals of both types can be highly plastic in their social and foraging behaviours. Our results in the Elacatinus species suggest that morphological adaptations of the brain are likely to be found in specialists whereas species that are more flexible in their habitat may only show behavioural plasticity without showing anatomical differences., (© 2024 S. Karger AG, Basel.)

Jumping spiders have extraordinary vision. Using multiple, specialized eyes, these spiders selectively gather and integrate disparate streams of information about motion, color, and spatial detail. The saccadic movements of a forward-facing pair of eyes allow spiders to inspect their surroundings and identify objects. Here, we discuss the jumping spider visual system and how visual information is attended to and processed., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Ltd.)

Background: By examining species-specific innate behaviours, neuroethologists have characterized unique neural strategies and specializations from throughout the animal kingdom. Simultaneously, the field of evolutionary developmental biology (informally, "evo-devo") seeks to make inferences about animals' evolutionary histories through careful comparison of developmental processes between species, because evolution is the evolution of development. Yet despite the shared focus on cross-species comparisons, there is surprisingly little crosstalk between these two fields. Insights can be gleaned at the intersection of neuroethology and evo-devo. Every animal develops within an environment, wherein ecological pressures advantage some behaviours and disadvantage others. These pressures are reflected in the neurodevelopmental strategies employed by different animals across taxa., Summary: Vision is a system of particular interest for studying the adaptation of animals to their environments. The visual system enables a wide variety of animals across the vertebrate lineage to interact with their environments, presenting a fantastic opportunity to examine how ecological pressures have shaped animals' behaviours and developmental strategies. Applying a neuroethological lens to the study of visual development, we advance a novel theory that accounts for the evolution of spontaneous retinal waves, an important phenomenon in the development of the visual system, across the vertebrate lineage., Key Messages: We synthesize literature on spontaneous retinal waves from across the vertebrate lineage. We find that ethological considerations explain some cross-species differences in the dynamics of retinal waves. In zebrafish, retinal waves may be more important for the development of the retina itself, rather than the retinofugal projections. We additionally suggest empirical tests to determine whether Xenopus laevis experiences retinal waves., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

Spatial memory helps animals to navigate familiar environments. In insects, spatial memory has extensively been studied in central place foragers such as ants and bees. However, if butterflies memorize a spatial location remains unclear. Here, we conducted behavioural experiments to test whether monarch butterflies ( Danaus plexippus ) can remember and retrieve the spatial location of a food source. We placed several visually identical feeders in a flight cage, with only one feeder providing sucrose solution. Across multiple days, individual butterflies predominantly visited the rewarding feeder. Next, we displaced a salient landmark close to the feeders to test which visual cue the butterflies used to relocate the rewarding feeder. While occasional landmark displacements were ignored by the butterflies and did not affect their decisions, systematic displacement of both the landmark and the rewarding feeder demonstrated that the butterflies associated the salient landmark with the feeder's position. Altogether, we show that butterflies consolidate and retrieve spatial memory in the context of foraging.

More than a century of research, of which JEB has published a substantial selection, has highlighted the rich diversity of animal eyes. From these studies have emerged numerous examples of visual systems that depart from our own familiar blueprint, a single pair of lateral cephalic eyes. It is now clear that such departures are common, widespread and highly diverse, reflecting a variety of different eye types, visual abilities and architectures. Many of these examples have been described as 'distributed' visual systems, but this includes several fundamentally different systems. Here, I re-examine this term, suggest a new framework within which to evaluate visual system distribution in both spatial and functional senses, and propose a roadmap for future work. The various architectures covered by this term reflect three broad strategies that offer different opportunities and require different approaches for study: the duplication of functionally identical eyes, the expression of multiple, functionally distinct eye types in parallel and the use of dispersed photoreceptors to mediate visual behaviour without eyes. Within this context, I explore some of the possible implications of visual system architecture for how visual information is collected and integrated, which has remained conceptually challenging in systems with a large degree of spatial and/or functional distribution. I highlight two areas that should be prioritised in future investigations: the whole-organism approach to behaviour and signal integration, and the evolution of visual system architecture across Metazoa. Recent advances have been made in both areas, through well-designed ethological experiments and the deployment of molecular tools., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Quantifying animal behaviour during microscopy is crucial to associate optically recorded neural activity with behavioural outputs and states. Here, I describe an imaging and tracking system for head-restrained larval zebrafish compatible with functional microscopy. This system is based on the Raspberry Pi computer, Pi NoIR camera and open-source software for the real-time tail segmentation and skeletonization of the zebrafish tail at over 100 Hz. This allows for precise and long-term analyses of swimming behaviour, which can be related to functional signals recorded in individual neurons. This system offers a simple but performant solution for quantifying the behaviour of head-restrained larval zebrafish, which can be built for 340€., Competing Interests: Competing interests The author declares no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Background: Plants often use floral displays to attract mutualists and prevent antagonist attacks. Chemical displays detectable from a distance include attractive or repellent floral volatile organic compounds (FVOCs). Locally, visitors perceive contact chemicals including nutrients but also deterrent or toxic constituents of pollen and nectar. The FVOC and pollen chemical composition can vary intra- and interspecifically. For certain pollinator and florivore species, responses to these compounds are studied in specific plant systems, yet we lack a synthesis of general patterns comparing these two groups and insights into potential correlations between FVOC and pollen chemodiversity., Scope: We reviewed how FVOCs and non-volatile floral chemical displays, i.e. pollen nutrients and toxins, vary in composition and affect the detection by and behaviour of insect visitors. Moreover, we used meta-analyses to evaluate the detection of and responses to FVOCs by pollinators vs. florivores within the same plant genera. We also tested whether the chemodiversity of FVOCs, pollen nutrients and toxins is correlated, hence mutually informative., Key Results: According to available data, florivores could detect more FVOCs than pollinators. Frequently tested FVOCs were often reported as pollinator-attractive and florivore-repellent. Among FVOCs tested on both visitor groups, there was a higher number of attractive than repellent compounds. FVOC and pollen toxin richness were negatively correlated, indicating trade-offs, whereas a marginal positive correlation between the amount of pollen protein and toxin richness was observed., Conclusions: Plants face critical trade-offs, because floral chemicals mediate similar information to both mutualists and antagonists, particularly through attractive FVOCs, with fewer repellent FVOCs. Furthermore, florivores might detect more FVOCs, whose richness is correlated with the chemical richness of rewards. Chemodiversity of FVOCs is potentially informative of reward traits. To gain a better understanding of the ecological processes shaping floral chemical displays, more research is needed on floral antagonists of diverse plant species and on the role of floral chemodiversity in visitor responses., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company.)

An increasingly popular animal model for studying the neural basis of social behavior, cognition, and communication is the common marmoset (Callithrix jacchus). Interest in this New World primate across neuroscience is now being driven by their proclivity for prosociality across their repertoire, high volubility, and rapid development, as well as their amenability to naturalistic testing paradigms and freely moving neural recording and imaging technologies. The complement of these characteristics set marmosets up to be a powerful model of the primate social brain in the years to come. Here, we focus on vocal communication because it is the area that has both made the most progress and illustrates the prodigious potential of this species. We review the current state of the field with a focus on the various brain areas and networks involved in vocal perception and production, comparing the findings from marmosets to other animals, including humans., (© 2023 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals LLC on behalf of New York Academy of Sciences.)

A very quick decision enables hunting archerfish to secure downed prey even when they are heavily outnumbered by competing other surface-feeding fish. Based exclusively on information that is taken briefly after the onset of prey motion, the fish select a rapid C-start that turns them right towards the later point of catch. Moreover, the C-start, and not later fin strokes, already lends the fish the speed needed to arrive at just the right time. The archerfish predictive C-starts are kinematically not distinguishable from escape C-starts made by the same individual and are among the fastest C-starts known in teleost fish. The start decisions allow the fish-for ballistically falling prey-to respond accurately to any combination of the initial variables of prey movement and for any position and orientation of the responding fish. The start decisions do not show a speed-accuracy tradeoff and their accuracy is buffered against substantial changes of environmental parameters. Here, I introduce key aspects of this high-speed decision that combines speed, complexity, and precision in an unusual way., (© 2023. The Author(s).)

Psychology and neuroscience are concerned with the study of behavior, of internal cognitive processes, and their neural foundations. However, most laboratory studies use constrained experimental settings that greatly limit the range of behaviors that can be expressed. While focusing on restricted settings ensures methodological control, it risks impoverishing the object of study: by restricting behavior, we might miss key aspects of cognitive and neural functions. In this article, we argue that psychology and neuroscience should increasingly adopt innovative experimental designs, measurement methods, analysis techniques and sophisticated computational models to probe rich, ecologically valid forms of behavior, including social behavior. We discuss the challenges of studying rich forms of behavior as well as the novel opportunities offered by state-of-the-art methodologies and new sensing technologies, and we highlight the importance of developing sophisticated formal models. We exemplify our arguments by reviewing some recent streams of research in psychology, neuroscience and other fields (e.g., sports analytics, ethology and robotics) that have addressed rich forms of behavior in a model-based manner. We hope that these "success cases" will encourage psychologists and neuroscientists to extend their toolbox of techniques with sophisticated behavioral models - and to use them to study rich forms of behavior as well as the cognitive and neural processes that they engage., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

In this special issue of articles from leading neuroethologists-all of whom gave outstanding presentations within the Presidential Symposium of the 2022 International Congress of Neuroethology held in Lisbon, Portugal-we learn about the role of cryptochrome molecules in the magnetic sense of animals, how honeybees construct their honeycombs, why fish eyes are built the way they are in species from different depths, how archerfish intercept their newly downed prey with a swift muscular curving of the body (known as a C-start) and how birds process optic flow information to control flight. Each contribution showcases how nervous systems have evolved to control behaviour, the raison d'être of neuroethology., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Steroid hormones remodel neural networks to induce seasonal or developmental changes in behavior. Hormonal changes in behavior likely require coordinated changes in sensorimotor integration. Here, we investigate hormonal effects on a predictive motor signal, termed corollary discharge, that modulates sensory processing in weakly electric mormyrid fish. In the electrosensory pathway mediating communication behavior, inhibition activated by a corollary discharge blocks sensory responses to self-generated electric pulses, allowing the downstream circuit to selectively analyze communication signals from nearby fish. These pulses are elongated by increasing testosterone levels in males during the breeding season. We induced electric-pulse elongation using testosterone treatment and found that the timing of electroreceptor responses to self-generated pulses was delayed as electric-pulse duration increased. Simultaneous recordings from an electrosensory nucleus and electromotor neurons revealed that the timing of corollary discharge inhibition was delayed and elongated by testosterone. Furthermore, this shift in the timing of corollary discharge inhibition was precisely matched to the shift in timing of receptor responses to self-generated pulses. We then asked whether the shift in inhibition timing was caused by direct action of testosterone on the corollary discharge circuit or by plasticity acting on the circuit in response to altered sensory feedback. We surgically silenced the electric organ of fish and found similar hormonal modulation of corollary discharge timing between intact and silent fish, suggesting that sensory feedback was not required for this shift. Our findings demonstrate that testosterone directly regulates motor output and internal prediction of the resulting sensory consequences in a coordinated manner., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Internal models that predict the sensory consequences of motor actions are vital for sensory, motor, and cognitive functions. However, the relationship between motor action and sensory input is complex, often varying from one moment to another depending on the state of the animal and the environment. The neural mechanisms for generating predictions under such challenging, real-world conditions remain largely unknown. Using novel methods for underwater neural recording, a quantitative analysis of unconstrained behavior, and computational modeling, we provide evidence for an unexpectedly sophisticated internal model at the first stage of active electrosensory processing in mormyrid fish. Closed-loop manipulations reveal that electrosensory lobe neurons are capable of simultaneously learning and storing multiple predictions of the sensory consequences of motor commands specific to different sensory states. These results provide mechanistic insights into how internal motor signals and information about the sensory environment are combined within a cerebellum-like circuitry to predict the sensory consequences of natural behavior., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

How neural populations encode sensory input to generate behavioral responses remains a central problem in systems neuroscience. Here we investigated how neuromodulation influences population coding of behaviorally relevant stimuli to give rise to behavior in the electrosensory system of the weakly electric fish Apteronotus leptorhynchus . We performed multi-unit recordings from ON and OFF sensory pyramidal cells in response to stimuli whose amplitude (i.e., envelope) varied in time, before and after electrical stimulation of the raphe nuclei. Overall, raphe stimulation increased population coding by ON- but not by OFF-type cells, despite both cell types showing similar sensitivities to the stimulus at the single neuron level. Surprisingly, only changes in population coding by ON-type cells were correlated with changes in behavioral responses. Taken together, our results show that neuromodulation differentially affects ON vs. OFF-type cells in order to enhance perception of behaviorally relevant sensory input., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

From both comparative biology and translational research perspectives, there is escalating interest in understanding how animals navigate their environments. Considerable work is being directed towards understanding the sensory transduction and neural processing of environmental stimuli that guide animals to, for example, food and shelter. While much has been learned about the spatial orientation behavior, sensory cues, and neurophysiology of champion navigators such as bees and ants, many other, often overlooked animal species possess extraordinary sensory and spatial capabilities that can broaden our understanding of the behavioral and neural mechanisms of animal navigation. For example, arachnids are predators that often return to retreats after hunting excursions. Many of these arachnid central-place foragers are large and highly conducive to scientific investigation. In this review we highlight research on three orders within the Class Arachnida: Amblypygi (whip spiders), Araneae (spiders), and Scorpiones (scorpions). For each, we describe (I) their natural history and spatial navigation, (II) how they sense the world, (III) what information they use to navigate, and (IV) how they process information for navigation. We discuss similarities and differences among the groups and highlight potential avenues for future research., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Like many other animals, insects are capable of returning to previously visited locations using path integration, which is a memory of travelled direction and distance. Recent studies suggest that Drosophila can also use path integration to return to a food reward. However, the existing experimental evidence for path integration in Drosophila has a potential confound: pheromones deposited at the site of reward might enable flies to find previously rewarding locations even without memory. Here, we show that pheromones can indeed cause naïve flies to accumulate where previous flies had been rewarded in a navigation task. Therefore, we designed an experiment to determine if flies can use path integration memory despite potential pheromonal cues by displacing the flies shortly after an optogenetic reward. We found that rewarded flies returned to the location predicted by a memory-based model. Several analyses are consistent with path integration as the mechanism by which flies returned to the reward. We conclude that although pheromones are often important in fly navigation and must be carefully controlled for in future experiments, Drosophila may indeed be capable of performing path integration., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Historically, diverse organisms have contributed to our understanding of auditory function. In recent years, the laboratory mouse has become the prevailing non-human model in auditory research, particularly for biomedical studies. There are many questions in auditory research for which the mouse is the most appropriate (or the only) model system available. But mice cannot provide answers for all auditory problems of basic and applied importance, nor can any single model system provide a synthetic understanding of the diverse solutions that have evolved to facilitate effective detection and use of acoustic information. In this review, spurred by trends in funding and publishing and inspired by parallel observations in other domains of neuroscience, we highlight a few examples of the profound impact and lasting benefits of comparative and basic organismal research in the auditory system. We begin with the serendipitous discovery of hair cell regeneration in non-mammalian vertebrates, a finding that has fueled an ongoing search for pathways to hearing restoration in humans. We then turn to the problem of sound source localization - a fundamental task that most auditory systems have been compelled to solve despite large variation in the magnitudes and kinds of spatial acoustic cues available, begetting varied direction-detecting mechanisms. Finally, we consider the power of work in highly specialized organisms to reveal exceptional solutions to sensory problems - and the diverse returns of deep neuroethological inquiry - via the example of echolocating bats. Throughout, we consider how discoveries made possible by comparative and curiosity-driven organismal research have driven fundamental scientific, biomedical, and technological advances in the auditory field., Competing Interests: Declaration of Competing Interest The authors have no competing interests to declare., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

To evolve, and remain adaptive, collective behaviours must have a positive impact on overall individual fitness. However, these adaptive benefits may not be immediately apparent owing to an array of interactions with other ecological traits, which can depend on a lineage's evolutionary past and the mechanisms controlling group behaviour. A coherent understanding of how these behaviours evolve, are exhibited, and are coordinated across individuals, therefore requires an integrative approach spanning traditional disciplines in behavioural biology. Here, we argue that lepidopteran larvae are well placed to serve as study systems for investigating the integrative biology of collective behaviour. Lepidopteran larvae display a striking diversity in social behaviour, which illustrates critical interactions between ecological, morphological and behavioural traits. While previous, often classic, work has provided an understanding of how and why collective behaviours evolve in Lepidoptera, much less is known about the developmental and mechanistic basis of these traits. Recent advances in the quantification of behaviour, and the availability of genomic resources and manipulative tools, allied with the exploitation of the behavioural diversity of tractable lepidopteran clades, will change this. In doing so, we will be able to address previously intractable questions that can reveal the interplay between levels of biological variation. This article is part of a discussion meeting issue 'Collective behaviour through time'.

Many vertebrate species show breeding periods and exhibit series of characteristic species-specific sexual behaviors only during the breeding period. Here, secretion of gonadal sex hormones from the mature gonads has been considered to facilitate sexual behaviors. Thus, the sexual behavior has long been considered to be regulated by neural and hormonal mechanisms. In this review, we discuss recent progress in the study of neural control mechanisms of sexual behavior with a focus on studies using fish, which have often been the favorite animals used by many researchers who study instinctive animal behaviors. We first discuss control mechanisms of sexual behaviors by sex steroids in relation to the anatomical studies of sex steroid-concentrating neurons in various vertebrate brains, which are abundantly distributed in evolutionarily conserved areas such as preoptic area (POA) and anterior hypothalamus. We then focus on another brain area called the ventral telencephalic area, which has also been suggested to contain sex steroid-concentrating neurons and has been implicated in the control of sexual behaviors, especially in teleosts. We also discuss control of sex-specific behaviors and sexual preference influenced by estrogenic signals or by olfactory/pheromonal signals. Finally, we briefly summarize research on the modulatory control of motivation for sexual behaviors by a group of peptidergic neurons called terminal nerve gonadotropin-releasing hormone (TN-GnRH) neurons, which are known to be especially developed in fishes among various vertebrate species.

The learning flights and walks of bees, wasps and ants are precisely coordinated movements that enable insects to memorise the visual surroundings of their nest or other significant places such as foraging sites. These movements occur on the first few occasions that an insect leaves its nest. They are of special interest because their discovery in the middle of the 19th century provided perhaps the first evidence that insects can learn and are not solely governed by instinct. Here, we recount the history of research on learning flights from their discovery to the present day. The first studies were conducted by skilled naturalists and then, over the following 50 years, by neuroethologists examining the insects' learning behaviour in the context of experiments on insect navigation and its underlying neural mechanisms. The most important property of these movements is that insects repeatedly fixate their nest and look in other favoured directions, either in a preferred compass direction, such as North, or towards preferred objects close to the nest. Nest facing is accomplished through path integration. Memories of views along a favoured direction can later guide an insect's return to its nest. In some ant species, the favoured direction is adjusted to future foraging needs. These memories can then guide both the outward and homeward legs of a foraging trip. Current studies of central areas of the insect brain indicate what regions implement the behavioural manoeuvres underlying learning flights and the resulting visual memories., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

For three decades, IBNS has provided a forum for the dissemination of behavioral neuroscience research, broadly defined. Throughout this time, research presented at the annual meetings has reflected representative trends in the field with an emphasis on relevant preclinical animal models. From its inception, IBNS has contributed to my professional development and evolving research interests. Unsurprisingly, throughout the three decades of its existence, IBNS annual programs have reflected research trends that have been thoughtfully evaluated, challenged, and, in some cases, recalibrated. An emphasis in my lab, for example, has slowly navigated toward the inclusion of more diverse species (e.g., nonhuman primate models, wild rats, wild and captive raccoons) assessed in settings that reflect more ethological relevance than typically observed in traditional laboratory settings. Consequently, my research interests are pivoting from laboratory animal model exclusive (L.A.M.E.) endeavors to more natural, diverse, ethoexperimental approaches. As progress toward translational findings for psychiatric and neurological conditions is considered, it is recommended that researchers remain open to nontraditional methodological approaches that incorporate diverse animal models and assessments to inform laboratory-generated findings., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The marine mollusc Acanthopleura granulata (Mollusca; Polyplacophora) has a distributed visual array composed of hundreds of small image-forming eyes embedded within its eight dorsal shell plates. As in other animals with distributed visual systems, we still have a poor understanding of the visual capabilities of A. granulata and we have yet to learn where and how it processes visual information. Using behavioral trials involving isoluminant looming visual stimuli, we found that A. granulata demonstrates spatial vision with an angular resolution of 6 deg. We also found that A. granulata responds to looming stimuli defined by contrasting angles of linear polarization. To learn where and how A. granulata processes visual information, we traced optic nerves using fluorescent lipophilic dyes. We found that the optic nerves innervate the underlying lateral neuropil, a neural tissue layer that circumnavigates the body. Adjacent optic nerves innervate the lateral neuropil with highly overlapping arborizations, suggesting it is the site of an integrated visuotopic map. Using immunohistochemistry, we found that the lateral neuropil of A. granulata is subdivided into two separate layers. In comparison, we found that a chiton with eyespots (Chiton tuberculatus) and two eyeless chitons (Ischnochiton papillosus and Chaetopleura apiculata) have lateral neuropil that is a singular circular layer without subdivision, findings consistent with previous work on chiton neuroanatomy. Overall, our results suggest that A. granulata effectuates its visually mediated behaviors using a unique processing scheme: it extracts spatial and polarization information using a distributed visual system, and then integrates and processes that information using decentralized neural circuits., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Background: Knowledge on the neurobiological systems underlying psychiatric disorders has considerably evolved due to findings on basic research using animal models. Anxiety-like behaviors in rodents are widely explored in neuroethological apparatuses, such as the light-dark box (LDB) test through different protocols, which have been shown to influence the behavioral outcomes and probably the activation of the hypothalamic-pituitary-adrenal (HPA) axis., New Method: Adult male Wistar rats were submitted to LDB in different room illumination conditions (25/0, 65/0 and/or 330/0 lux), initial positioning in the LDB compartments and previous stressful experience in the Elevated Plus Maze (EPM) or restraint stress (RS). Rats' behavior (exploratory and risk assessment) was registered during a 15 min period, divided into blocks of 5 min RESULTS: Exploration of the lit compartment decreased in higher luminosity condition, as after positioning rats in the dark compartment or previous exposure to the EPM, while low luminosity increased exploration of the LDB. No differences were observed on serum corticosterone in all groups and experimental conditions., Comparison With Existing Methods: Light intensity and test duration influenced exploration of the LDB jeopardizing the anxiolytic/anxiogenic effects. Low light intensity increased exploration, while high intensity decreased it. These results suggest that 65/0 lux is a neutral condition to investigate possible anxiolytic/anxiogenic effects of drugs and/or exposure to previous aversive stimuli as the EPM., Conclusions: Different factors impact on exploratory and risk assessment behaviors which may be related to safety maximization behavior. Unraveling how different factors affect behavior may be a crucial step towards understanding its expression and the contributions on advances in the physiopathology 1 and treatment of psychiatric disorders., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Rapid anthropogenic environmental changes, including those due to habitat contamination, degradation, and climate change, have far-reaching effects on biological systems that may outpace animals' adaptive responses. Neurobiological systems mediate interactions between animals and their environments and evolved over millions of years to detect and respond to change. To gain an understanding of the adaptive capacity of nervous systems given an unprecedented pace of environmental change, mechanisms of physiology and behavior at the cellular and biophysical level must be examined. While behavioral changes resulting from anthropogenic activity are becoming increasingly described, identification and examination of the cellular, molecular, and circuit-level processes underlying those changes are profoundly underexplored. Hence, the field of neuroscience lacks predictive frameworks to describe which neurobiological systems may be resilient or vulnerable to rapidly changing ecosystems, or what modes of adaptation are represented in our natural world. In this review, we highlight examples of animal behavior modification and corresponding nervous system adaptation in response to rapid environmental change. The underlying cellular, molecular, and circuit-level component processes underlying these behaviors are not known and emphasize the unmet need for rigorous scientific enquiry into the neurobiology of changing ecosystems., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Michaiel and Bernard.)

Neurons receive information through their synaptic inputs, but the functional significance of how those inputs are mapped on to a cell's dendrites remains unclear. We studied this question in a grasshopper visual neuron that tracks approaching objects and triggers escape behavior before an impending collision. In response to black approaching objects, the neuron receives OFF excitatory inputs that form a retinotopic map of the visual field onto compartmentalized, distal dendrites. Subsequent processing of these OFF inputs by active membrane conductances allows the neuron to discriminate the spatial coherence of such stimuli. In contrast, we show that ON excitatory synaptic inputs activated by white approaching objects map in a random manner onto a more proximal dendritic field of the same neuron. The lack of retinotopic synaptic arrangement results in the neuron's inability to discriminate the coherence of white approaching stimuli. Yet, the neuron retains the ability to discriminate stimulus coherence for checkered stimuli of mixed ON/OFF polarity. The coarser mapping and processing of ON stimuli thus has a minimal impact, while reducing the total energetic cost of the circuit. Further, we show that these differences in ON/OFF neuronal processing are behaviorally relevant, being tightly correlated with the animal's escape behavior to light and dark stimuli of variable coherence. Our results show that the synaptic mapping of excitatory inputs affects the fine stimulus discrimination ability of single neurons and document the resulting functional impact on behavior., Competing Interests: RD, YZ, ME, RM, FG No competing interests declared, (© 2022, Dewell, Zhu et al.)

Translational research in behavioral neuroscience seeks causes and remedies for human mental health problems in animals, following leads imposed by clinical research in psychiatry. This endeavor faces several problems because scientists must read and interpret animal movements to represent human perceptions, mood, and memory processes. Yet, it is still not known how mammalian brains bundle all these processes into a highly compressed motor output in the brain stem and spinal cord, but without that knowledge, translational research remains aimless. Based on some four decades of experience in the field, the article identifies sources of interpretation problems and illustrates typical translational pitfalls. (1) The sensory world of mice is different. Smell, hearing, and tactile whisker sensations dominate in rodents, while visual input is comparatively small. In humans, the relations are reversed. (2) Mouse and human brains are equated inappropriately: the association cortex makes up a large portion of the human neocortex, while it is relatively small in rodents. The predominant associative cortex in rodents is the hippocampus itself, orchestrating chiefly inputs from secondary sensorimotor areas and generating species-typical motor patterns that are not easily reconciled with putative human hippocampal functions. (3) Translational interpretation of studies of memory or emotionality often neglects the ecology of mice, an extremely small species surviving by freezing or flight reactions that do not need much cognitive processing. (4) Further misinterpretations arise from confounding neuronal properties with system properties, and from rigid mechanistic thinking unaware that many experimentally induced changes in the brain do partially reflect unpredictable compensatory plasticity. (5) Based on observing hippocampal lesion effects in mice indoors and outdoors, the article offers a simplistic general model of hippocampal functions in relation to hypothalamic input and output, placing hypothalamus and the supraspinal motor system at the top of a cerebral hierarchy. (6) Many translational problems could be avoided by inclusion of simple species-typical behaviors as end-points comparable to human cognitive or executive processing, and to rely more on artificial intelligence for recognizing patterns not classifiable by traditional psychological concepts., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Lipp and Wolfer.)

Cold environment is an inevitable stress source for humans and livestock in cold areas, which easily induce a cold stress response and then cause a series of abnormal changes in energy metabolism, neuroendocrine system, behavior and emotion. Homeostasis is maintained by the unified regulation of the autonomic nervous system, endocrine system, metabolism and behavior under cold exposure. Behavior is an indispensable part of the functional regulation of the body to respond to environmental changes. At present, the behavioral changes caused by cold exposure are unclear or even chaotic due to the difficulty of defining cold stress. Therefore, this study aims to systematically observe the changes in spontaneous movement, exploratory behavior and anxiety of mice under different intensity cold exposure and summarize the characteristics and behavior traits combined with relevant blood physiological indexes under corresponding conditions. Mice models of cold stress with different intensities were established (cold exposure gradients were 22 °C, 16 °C, 10 °C and 4 °C, and time gradients of each temperature were 2 h, 4 h, 6 h, 8 h, 10 h and 12 h). After the corresponding cold exposure treatment, mice immediately carried out the open field test(OFT) and elevated plus maze test (PMT) to evaluate their spontaneous movement, exploratory behavior and anxiety. Subsequently, blood samples were collected and used for the determination of corticosterone (Cort), corticotropin-releasing hormone (CRH), epinephrine (E), norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT) by enzyme-linked immunosorbent assay (ELISA). Spontaneous movement of mice increased under 22 °C cold exposure, but their exploration behavior did not significantly change, and their anxiety improved at the initial stage. The spontaneous movement and anxiety of mice increased in the initial stage and decreased in the later stage under cold exposure at 16, 10 and 4 °C and the exploratory behavior was inhibited. The hypothalamic-pituitary-adrenal (HPA) axis and locus coeruleus-noradrenergic (LC/NE) system were activated by cold stress and fluctuated with different intensities of cold exposure. Meanwhile, serum DA increased, and 5-HT was the opposite under different intensities of cold exposure. In conclusion, mild acute cold exposure promoted the spontaneous movement, increased exploratory behavior and improved anxiety. As the intensity of cold exposure increases, cold exposure had a negative effect on spontaneous movement, exploratory behavior and emotion. The physiological basis of these behavioral and emotional changes in mice under different intensity cold stimulation is the fluctuation of Cort, CRH, E, NE, DA and 5-HT.

Recent studies conducted in the natural habitats of songbirds have provided new insights into the neural mechanisms of turn-taking. For example, female and male plain-tailed wrens ( Pheugopedius euophrys ) sing a duet that is so precisely timed it sounds as if a single bird is singing. In this review, we discuss our studies examining the sensory and motor cues that pairs of wrens use to coordinate the rapid alternation of syllable production. Our studies included behavioral measurements of freely-behaving wrens in their natural habitat and neurophysiological experiments conducted in awake and anesthetized individuals at field sites in Ecuador. These studies show that each partner has a pattern-generating circuit in their brain that is linked via acoustic feedback between individuals. A similar control strategy has been described in another species of duetting songbird, white-browed sparrow-weavers ( Plocepasser mahali ). Interestingly, the combination of neurophysiological results from urethane-anesthetized and awake wrens suggest a role for inhibition in coordinating the timing of turn-taking. Finally, we highlight some of the unique challenges of conducting these experiments at remote field sites., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Coleman, Day and Fortune.)

Although rodents have represented the most intensely studied animals in neurobiological investigations for more than a century, few studies have systematically compared neural and endocrine differences between wild rodents in their natural habitats and laboratory strains raised in traditional laboratory environments. In the current study, male and female Rattus norvegicus rats were trapped in an urban setting and compared to weight-and sex-matched conspecifics living in standard laboratory housing conditions. Brains were extracted for neural assessments and fecal boli were collected for endocrine [corticosterone and dehydroepiandrosterone (DHEA)] assays. Additionally, given their role in immune and stress functions, spleen and adrenal weights were recorded. A separate set of wild rats was trapped at a dairy farm and held in captivity for one month prior to assessments; in these animals, brains were processed but no hormone data were available. The results indicated that wild-trapped rats exhibited 31% heavier brains, including higher densities of cerebellar neurons and glial cells in the bed nucleus of the stria terminalis. The wild rats also had approximately 300% greater spleen and adrenal weights, and more than a six-fold increase in corticosterone levels than observed in laboratory rats. Further research on neurobiological variables in wild vs. lab animals will inform the extensive neurobiological knowledge base derived from laboratory investigations using selectively bred rodents in laboratory environments, knowledge that will enhance the translational value of preclinical laboratory rodent studies., (Copyright © 2022 Elsevier B.V. All rights reserved.)

All species within the conch snail family Strombidae possess large camera-type eyes that are surprisingly well-developed compared with those found in most other gastropods. Although these eyes are known to be structurally complex, very little research on their visual function has been conducted. Here, we use isoluminant expanding visual stimuli to measure the spatial resolution and contrast sensitivity of a strombid, Conomurex luhuanus. Using these stimuli, we show that this species responds to objects as small as 1.06 deg in its visual field. We also show that C. luhuanus responds to Michelson contrasts of 0.07, a low contrast sensitivity between object and background. The defensive withdrawal response elicited by visual stimuli of such small angular size and low contrast suggests that conch snails may use spatial vision for the early detection of potential predators. We support these findings with morphological estimations of spatial resolution of 1.04 deg. These anatomical data therefore agree with the behavioural measures and highlight the benefits of integrating behavioural and morphological approaches in animal vision studies. Using contemporary imaging techniques [serial block-face scanning electron microscopy (SBF-SEM), in conjunction with transmission electron microscopy (TEM)], we found that C. luhuanus have more complex retinas, in terms of cell type diversity, than expected based on previous studies of the group using TEM alone. We find the C. luhuanus retina comprises six cell types, including a newly identified ganglion cell and accessory photoreceptor, rather than the previously described four cell types., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

A central aim of neuroethological research is to discover the mechanisms of natural behaviors in controlled laboratory studies. This goal, however, comes with challenges, namely the selection of experimental paradigms that allow full expression of natural behaviors. Here, we explore this problem in echolocating bats that evolved Doppler shift compensation (DSC) of sonar vocalizations to yield close matching between echo frequency and hearing sensitivity. We ask if behavioral tasks influence the precision of DSC in Pratt's roundleaf bat, Hipposideros pratti , in three classic laboratory paradigms evoking audio-vocal adjustments: Stationary bats listening to echo playbacks, bats transported on a moving pendulum, and bats flying freely. We found that experimental conditions had a strong influence on the expression of the audiovocal frequency adjustments in bats. H. pratti exhibited robust DSC in both free-flying and moving-pendulum experiments but did not exhibit consistent audiovocal adjustments in echo playback experiments. H. pratti featured a maximum compensation magnitude of 87% and a compensation precision of 0.27% in the free flight experiment. Interestingly, in the moving pendulum experiment H. pratti displayed surprisingly high-precision DSC, with an 84% maximum compensation magnitude and a 0.27% compensation precision. Such DSC performance places H. pratti among the bat species exhibiting the most precise audio-vocal control of echo frequency. These data support the emerging view that Hipposiderid bats have a high-precision DSC system and highlight the importance of selecting experimental paradigms that yield the expression of robust natural behaviors., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Luo, Lu, Wang, Wang and Moss.)

Polarisation vision is commonplace among invertebrates; however, most experiments focus on determining behavioural and/or neurophysiological responses to static polarised light sources rather than moving patterns of polarised light. To address the latter, we designed a polarisation stimulation device based on superimposing polarised and non-polarised images from two projectors, which can display moving patterns at frame rates exceeding invertebrate flicker fusion frequencies. A linear polariser fitted to one projector enables moving patterns of polarised light to be displayed, whilst the other projector contributes arbitrary intensities of non-polarised light to yield moving patterns with a defined polarisation and intensity contrast. To test the device, we measured receptive fields of polarisation-sensitive Argynnis paphia butterfly photoreceptors for both non-polarised and polarised light. We then measured local motion sensitivities of the optic flow-sensitive lobula plate tangential cell H1 in Calliphora vicina blowflies under both polarised and non-polarised light, finding no polarisation sensitivity in this neuron., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

Neophobia - an animal's reluctance to approach novel objects, try new foods, or explore unfamiliar environments - affects whether animals can adapt to new environments and exploit novel resources. However, despite its importance, the neurobiological mechanisms underlying this personality trait are poorly understood. In this study, we examined regional brain activity using the expression of two immediate early genes (IEGs), ZENK and c-Fos, in response to novel objects or control conditions in captive house sparrows (Passer domesticus, n = 22). When exposed to novel objects, we predicted that we would see differential IEG activity in brain regions involved in regulating stress and emotion (hippocampus, medial ventral arcopallium, lateral septum), reward and learning (striatum), and executive function (NCL) between neophobic and non-neophobic individuals. To classify birds by phenotype, we used behavior trials that tested willingness to approach a food dish in the presence of several different novel objects, habituation to one novel object, and willingness to try several different novel foods. We then exposed birds to a new novel object or a control condition and assessed protein expression of two IEGs in neophobic vs non-neophobic individuals after this final exposure. An analysis of average sparrow feeding times in the presence of novel objects showed a bimodal distribution of neophobia behavior. There was also high repeatability of individual novel object responses, and average responses to all three trial types (novel object, novel food, and habituation to a novel object) were significantly correlated. Although we saw no differences between neophobic and non-neophobic birds in IEG expression in response to novel objects in any of the 6 brain regions examined, there was a significant global decrease in ZENK expression and a significant increase in c-Fos expression in the medial ventral arcopallium and the caudal hippocampus in response to novel objects compared to controls, suggesting that these two regions may be important in novelty detection and threat perception. Additionally, there was no object effect in the rostral hippocampus, which supports the hypothesis that the avian hippocampus may have a rostrocaudal functional gradient similar to the septotemporal gradient in mammals., (Copyright © 2022 Elsevier B.V. All rights reserved.)