A perspective on neuroethology: what the past teaches us about the future of neuroethology

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.

Centennial issue

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.

Fantastic beasts and how to study them: rethinking experimental animal behavior

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.

'Distributed' vision and the architecture of animal visual systems

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.

pi_tailtrack: A compact, inexpensive and open-source behaviour-tracking system for head-restrained zebrafish

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€.

The archerfish predictive C-start

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.

The Presidential Symposium at the International Congress of Neuroethology 2022 in Lisbon, Portugal

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.

Beyond simple laboratory studies: Developing sophisticated models to study rich behavior

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.

Serotonin increases population coding of behaviorally relevant stimuli by enhancing responses of ON but not OFF-type sensory neurons

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.

Displacement experiments provide evidence for path integration in Drosophila

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.

On the value of diverse organisms in auditory research: From fish to flies to humans

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.

An 'instinct for learning': the learning flights and walks of bees, wasps and ants from the 1850s to now

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.

Wild brains: The value of neuroethological approaches in preclinical behavioral neuroscience animal models

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.

Polarization sensitivity and decentralized visual processing in an animal with a distributed visual system

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.

Comparative biology of spatial navigation in three arachnid orders (Amblypygi, Araneae, and Scorpiones)

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.

Exploring the light/dark box test: Protocols and implications for neuroscience research

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.

The marine gastropod Conomurex luhuanus (Strombidae) has high-resolution spatial vision and eyes with complex retinas

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.

Summary: Behavioural trials indicate the eyes of conch snail Conomurex luhuanus provide high-resolution spatial vision, and morphological examination reveals the retina contains more cell types than those of other gastropods.

Generating spatiotemporal patterns of linearly polarised light at high frame rates for insect vision research

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.

Summary: Design of a versatile visual stimulation device for presenting moving patterns of polarised light, and demonstration of its use to characterise polarisation sensitivity in butterfly photoreceptors and blowfly motion-sensitive interneurons.

From Karl von Frisch to Neuroethology: A Methodological Perspective on the Frischean Tradition's Expansion into Neuroethology

This paper examines a tradition of eusocial insect research stemming from the Austrian zoologist Karl von Frisch. As I show in this paper, one of the most enduring features of the Frischean tradition has been an experimental methodology developed by Frisch in the early 1910s. By tracing this methodology's use through Frisch's student, Martin Lindauer, and two of Lindauer's students, Rüdiger Wehner and Randolf Menzel, this paper illuminates a surprising aspect of ethology's development during the last half of the 20^th century. Namely, it sheds light on how the Frischean tradition, a tradition that had a complicated relationship with ethology since the discipline's formation in the 1930s, produced scientists who became leading figures in neuroethology, the most prominent contemporary field of behavioral research to retain the label of "ethology." Some of the features that distinguished Frisch's training method from the program of classical ethology and the work of his contemporaries later helped his academic descendants adapt the method to the neuroethological program.

A dynamical systems view of neuroethology: Uncovering stateful computation in natural behaviors

State-dependent computation is key to cognition in both biological and artificial systems. Alan Turing recognized the power of stateful computation when he created the Turing machine with theoretically infinite computational capacity in 1936. Independently, by 1950, ethologists such as Tinbergen and Lorenz also began to implicitly embed rudimentary forms of state-dependent computation to create qualitative models of internal drives and naturally occurring animal behaviors. Here, we reformulate core ethological concepts in explicitly dynamical systems terms for stateful computation. We examine, based on a wealth of recent neural data collected during complex innate behaviors across species, the neural dynamics that determine the temporal structure of internal states. We will also discuss the degree to which the brain can be hierarchically partitioned into nested dynamical systems and the need for a multi-dimensional state-space model of the neuromodulatory system that underlies motivational and affective states.

Bumblebees display characteristics of active vision during robust obstacle avoidance flight

Insects are remarkable flyers and capable of navigating through highly cluttered environments. We tracked the head and thorax of bumblebees freely flying in a tunnel containing vertically oriented obstacles to uncover the sensorimotor strategies used for obstacle detection and collision avoidance. Bumblebees presented all the characteristics of active vision during flight by stabilizing their head relative to the external environment and maintained close alignment between their gaze and flightpath. Head stabilization increased motion contrast of nearby features against the background to enable obstacle detection. As bees approached obstacles, they appeared to modulate avoidance responses based on the relative retinal expansion velocity (RREV) of obstacles and their maximum evasion acceleration was linearly related to RREVmax. Finally, bees prevented collisions through rapid roll manoeuvres implemented by their thorax. Overall, the combination of visuo-motor strategies of bumblebees highlights elegant solutions developed by insects for visually guided flight through cluttered environments.

It's all about seeing and hearing: the Editors' and Readers' Choice Awards 2022

This year marks the inauguration of the annual Editors' Choice Award and the Readers' Choice Award, each presented for outstanding original papers and review articles published in the Journal of Comparative Physiology A. The winners of the 2022 Editors' Choice Award were determined by vote of the Editorial Board for the most highly recommended papers published in Volume 207 in 2021. They are 'Visual discrimination and resolution in freshwater stingrays (Potamotrygon motoro)' by Daniel et al. (J Comp Physiol A 207, 43-58, 2021) in the Original Paper category; and 'Neurophysiology goes wild: from exploring sensory coding in sound proof rooms to natural environments' by Römer (J Comp Physiol A 207, 303-319, 2021) in the Review Article category. The 2022 Readers' Choice Award was based on access number of articles published in Volume 206 in 2020, to ensure at least 12-month online presence. It is given to Nicholas et al. for their original paper titled 'Visual motion sensitivity in descending neurons in the hoverfly' (J Comp Physiol A 206, 149-163, 2020); and to Schnaitmann et al. for their review article entitled 'Color vision in insects: insights from Drosophila' (J Comp Physiol A 206, 183-198, 2020).

The female sex pheromone (Z)-4-undecenal mediates flight attraction and courtship in Drosophila melanogaster

Specific mate communication and recognition underlies reproduction and hence speciation. Our study provides new insights in Drosophila melanogaster premating olfactory communication. Mate communication evolves during adaptation to ecological niches and makes use of social signals and habitat cues. Female-produced, species-specific volatile pheromone (Z)-4-undecenal (Z4-11Al) and male pheromone (Z)-11-octadecenyl acetate (cVA) interact with food odour in a sex-specific manner. Furthermore, Z4-11Al, which mediates upwind flight attraction in both sexes, also elicits courtship in experienced males. Two isoforms of the olfactory receptor Or69a are co-expressed in the same olfactory sensory neurons. Z4-11Al is perceived via Or69aB, while the food odorant (R)-linalool is a main ligand for the other variant, Or69aA. However, only Z4-11Al mediates courtship in experienced males, not (R)-linalool. Behavioural discrimination is reflected by calcium imaging of the antennal lobe, showing distinct glomerular activation patterns by these two compounds. Male sex pheromone cVA is known to affect male and female courtship at close range, but does not elicit upwind flight attraction as a single compound, in contrast to Z4-11Al. A blend of the food odour vinegar and cVA attracted females, while a blend of vinegar and female pheromone Z4-11Al attracted males, instead. Sex-specific upwind flight attraction to blends of food volatiles and male and female pheromone, respectively, adds a new element to Drosophila olfactory premating communication and is an unambiguous paradigm for identifying the behaviourally active components, towards a more complete concept of food-pheromone odour objects.

The Journal of Comparative Physiology A: rooted in great tradition, committed to innovation and discovery

The current volume of the Journal of Comparative Physiology A marks a transition in editorship. This event provides the opportunity to reflect on the 98 years of the history of the Journal; on the impact of its legacy on the evolution of neuroethology and the comparative branches of sensory physiology and neurobiology; and on future changes in editorial organization and content.

[Effects of curcumin on neurobehavior and oxidative stress in hippocampus of rats exposed to manganese]

Objective: To establish the animal model of subchronic manganism, and to explore the effect of manganese on neurofunction of rats and the protective effect of curcumin on neurotoxicity of manganism rats. Methods: From July to December 2019, 80 SPF male SD rats were divided into 8 groups according to body weight by random number table method, which were blank control group, low, middle and high dose manganese exposure group, low, middle and high dose curcumin antagonistic group and curcumin group, with 10 rats in each group. The low, middle and high dose manganese groups were given intraperitoneal injection of 5 mg/kg, 10 mg/kg and 15 mg/kg MnCl(2)·4H(2)O respectively. The low, middle and high dose curcumin antagonistic groups were given 100 mg/kg, 200 mg/kg and 400 mg/kg curcumin orally along with 15 mg/kg MnCl(2)·4H(2)O intraperitoneal injection. Curcumin group was given 400 mg/kg curcumin orally. The rats were exposed to 5 days a week, once a day for 16 weeks. After exposure, neurobehavioral tests (balance beam test, Morris water maze, passive avoidance test) were carried out in each group. Hippocampus tissues were taken for pathological examination and oxidative stress indexes were detected. Results: The balance beam test results showed that, compared with the blank control group, the scores of balance beam of the rats in the middle and high dose manganese exposure groups increased (P<0.05) . Compared with the high dose manganese exposure group, the balance beam scores of the low, middle and high dose curcumin antagonistic groups were decreased (P<0.05) .The results of Morris water maze showed that, compared with the blank control group, the escape latency of middle and high dose manganese exposure groups was prolonged from the third day (P<0.05) , and the average number of crossing the platform area of each manganese exposure group was decreased (P<0.05) .Compared with the high dose manganese exposure group, the escape latency of the middle and high dose curcumin antagonistic groups was shortened (P<0.05) , and the average number of crossing the original platform was increased (P<0.05) . The results of passive avoidance test show that, compared with the blank control group, the number of errors were increased in middle and high dose manganese exposure groups (P<0.05) . Compared with the high dose manganese exposure group, the number of errors in the passive avoidance test in the middle and high dose curcumin antagonistic groups were decreased (P<0.05) . Pathological examination showed that the rats treated with manganses had different degrees of degeneration and necrosis of nerve cells, and the structure of nerve cells was blurred and the number of nerve cells decreased. The above phenomena were improved after curcumin antagonism. The results of oxidative stress index showed that, compared with blank control group, the activity of superoxide dismutase (SOD) decreased and the content of malondialdehyde (MDA) increased in the hippocampus of rats exposed to middle and high dose of manganese (P<0.05) . Compared with the high dose manganese exposure group, the SOD activity increased and the MDA content decreased in the middle and high dose antagonist group (P<0.05) . Conclusion: Subchronic manganese exposure can reduce the balance function, learning and memory ability of rats, and damage the hippocampal nerve cells in oxidative stress state. Curcumin can improve the balance function and learning and memory ability of rats with manganese poisoning, improve the hippocampal nerve damage caused by manganese exposure, and has a certain protective effect on manganese induced neurotoxicity.

Neural substrates involved in the cognitive information processing in teleost fish

Over the last few decades, it has been shown that fish, comprising the largest group of vertebrates and in many respects one of the least well studied, possess many cognitive abilities comparable to those of birds and mammals. Despite a plethora of behavioural studies assessing cognition abilities and an abundance of neuroanatomical studies, only few studies have aimed to or in fact identified the neural substrates involved in the processing of cognitive information. In this review, an overview of the currently available studies addressing the joint research topics of cognitive behaviour and neuroscience in teleosts (and elasmobranchs wherever possible) is provided, primarily focusing on two fundamentally different but complementary approaches, i.e. ablation studies and Immediate Early Gene (IEG) analyses. More recently, the latter technique has become one of the most promising methods to visualize neuronal populations activated in specific brain areas, both during a variety of cognitive as well as non-cognition-related tasks. While IEG studies may be more elegant and potentially easier to conduct, only lesion studies can help researchers find out what information animals can learn or recall prior to and following ablation of a particular brain area.

Archerfish coordinate fin maneuvers with their shots

Archerfish down a variety of aerial prey from a range of distances using water jets that they adjust to the size and distance of their prey. We describe here that characteristic rapid fin maneuvers, most notably of the pectoral and pelvic fins, are precisely coordinated with the release of the jet. We discovered these maneuvers in two fish, the jets of which had been characterized in detail, that had been trained to shoot from fixed positions at targets at different heights and that remained stable during their shots. Based on the findings in these individuals, we examined shooting-associated fin movement in 28 further archerfish of two species that could shoot from freely chosen positions at targets at different heights. Slightly before the onset of the water jet, at a time when the shooter remains stable, the pectoral fins of all shooters switched from asynchronous low-amplitude beating to a synchronized rapid forward flap. The onset and duration of the forward and subsequent backward flap were robust across all individuals and shooting angles but depended on target height. The pelvic fins were slowly adducted at the start of the jet and stopped moving after its release. All other fins also showed a characteristic sequence of activation, some starting ∼0.5 s before the shot. Our findings suggest that shooting-related fin maneuvers are needed to stabilize the shooter, and that these maneuvers are an important component in the precise and powerful far-distance shooting in archerfish.

A spider in motion: facets of sensory guidance

Spiders show a broad range of motions in addition to walking and running with their eight coordinated legs taking them towards their resources and away from danger. The usefulness of all these motions depends on the ability to control and adjust them to changing environmental conditions. A remarkable wealth of sensory receptors guarantees the necessary guidance. Many facets of such guidance have emerged from neuroethological research on the wandering spider Cupiennius salei and its allies, although sensori-motor control was not the main focus of this work. The present review may serve as a springboard for future studies aiming towards a more complete understanding of the spider's control of its different types of motion. Among the topics shortly addressed are the involvement of lyriform slit sensilla in path integration, muscle reflexes in the walking legs, the monitoring of joint movement, the neuromuscular control of body raising, the generation of vibratory courtship signals, the sensory guidance of the jump to flying prey and the triggering of spiderling dispersal behavior. Finally, the interaction of sensors on different legs in oriented turning behavior and that of the sensory systems for substrate vibration and medium flow are addressed.

Olfactory systems across mosquito species

There are 3559 species of mosquitoes in the world (Harbach 2018) but, so far, only a handful of them have been a focus of olfactory neuroscience and neurobiology research. Here we discuss mosquito olfactory anatomy and function and connect these to mosquito ecology. We highlight the least well-known and thus most interesting aspects of mosquito olfactory systems and discuss promising future directions. We hope this review will encourage the insect neuroscience community to work more broadly across mosquito species instead of focusing narrowly on the main disease vectors.

Modulation of odour-guided behaviour in mosquitoes

Mosquitoes are emerging as model systems with which to study innate behaviours through neuroethology and functional genomics. Decades of work on these disease vectors have provided a solid behavioural framework describing the distinct repertoire of predominantly odour-mediated behaviours of female mosquitoes, and their dependence on life stage (intrinsic factors) and environmental cues (extrinsic factors). The purpose of this review is to provide an overview of how intrinsic factors, including adult maturation, age, nutritional status, and infection, affect the attraction to plants and feeding on plant fluids, host seeking, blood feeding, supplemental feeding behaviours, pre-oviposition behaviour, and oviposition in female mosquitoes. With the technological advancements in the recent two decades, we have gained a better understanding of which volatile organic compounds are used by mosquitoes to recognise and discriminate among various fitness-enhancing resources, and characterised their neural and molecular correlates. In this review, we present the state of the art of the peripheral olfactory system as described by the neural physiology, functional genomics, and genetics underlying the demonstrated changes in the behavioural repertoire in female mosquitoes. The review is meant as a summary introduction to the current conceptual thinking in the field.

Getting the Most Out of Your Zombie: Abdominal Sensors and Neural Manipulations Help Jewel Wasps Find the Roach's Weak Spot

The parasitoid emerald jewel wasp (Ampulex compressa) subdues the American cockroach (Periplaneta americana) with a sting to the 1st thoracic ganglion, followed by a sting to the roach's brain, causing long-term pacification. The wasp then leads the cockroach to a hole where it lays an egg on the roach middle leg before barricading the entrance and departing. Although many aspects of the wasp's initial attack have been investigated, few studies have detailed the egg-laying process and the subsequent fate of the larvae. Here I show that larval survival depends on precise egg positioning on the cockroach by the female wasp. Ablation of sensory hairs on the wasp's abdomen resulted in mislaid eggs, which seldom survived. In addition, the cockroach femur may block the oviposition site. The wasp contended with this challenge with a newly discovered suite of stings, 3 directed into the 2nd thoracic ganglion which resulted in extension of the femur, thus exposing the oviposition site and removing a potential barrier to the wasp's successful reproduction. When the femur was glued in place, the wasp stung the cockroach over 100 times, in an apparent fixed action pattern triggered by the obscured oviposition target. These findings highlight the importance of proper egg placement by the wasp, and reveal sensors and new neural manipulations that facilitate the process.

Progressive impairment of learning and memory in adult zebrafish treated by Al2O3 nanoparticles when in embryos

Al₂O₃ Nanoparticles (Al₂O₃-NPs) have been widely used because of their unique physical and chemical properties, and Al₂O₃-NPs can be released into the environment directly or indirectly. Our previous research found that 13 nm Al₂O₃-NPs can induce neural cell death and autophagy in primarily cultured neural cells in vitro. The aim of this study was to determine where Al₂O₃-NPs at 13 nm particle size can cause neural cells in vivo and assess related behavioural changes and involved potential mechanisms. Zebrafish from embryo to adult were selected as animal models. Learning and memory as functional indicators of neural cells in zebrafish were measured during the development from embryo to adult. Our results indicate that Al₂O₃-NPs treatment in zebrafish embryos stages can cause the accumulation of aluminium content in zebrafish brain tissue, leading to progressive impaired neurodevelopmental behaviours and latent learning and memory performance. Additionally, oxidative stress and disruption of dopaminergic transmission in zebrafish brain tissues are correlated with the dose-dependent and age-dependent accumulation of aluminium content. Moreover, the number of neural cells in the telencephalon tissue treated with Al₂O₃-NPs significantly declined, and the ultramicroscopic morphology indicated profound autophagy alternations. The results suggest that Al₂O₃-NPs has dose-dependent and time-dependent progressive damage on learning and memory performance in adult zebrafish when treated in embryos. This is the first study of the effects of Al₂O₃-NPs on learning and memory during the development of zebrafish from embryo to adult.

Behavioral Activity Recognition Based on Gaze Ethograms

Noninvasive behavior observation techniques allow more natural human behavior assessment experiments with higher ecological validity. We propose the use of gaze ethograms in the context of user interaction with a computer display to characterize the user's behavioral activity. A gaze ethogram is a time sequence of the screen regions the user is looking at. It can be used for the behavioral modeling of the user. Given a rough partition of the display space, we are able to extract gaze ethograms that allow discrimination of three common user behavioral activities: reading a text, viewing a video clip, and writing a text. A gaze tracking system is used to build the gaze ethogram. User behavioral activity is modeled by a classifier of gaze ethograms able to recognize the user activity after training. Conventional commercial gaze tracking for research in the neurosciences and psychology science are expensive and intrusive, sometimes impose wearing uncomfortable appliances. For the purposes of our behavioral research, we have developed an open source gaze tracking system that runs on conventional laptop computers using their low quality cameras. Some of the gaze tracking pipeline elements have been borrowed from the open source community. However, we have developed innovative solutions to some of the key issues that arise in the gaze tracker. Specifically, we have proposed texture-based eye features that are quite robust to low quality images. These features are the input for a classifier predicting the screen target area, the user is looking at. We report comparative results of several classifier architectures carried out in order to select the classifier to be used to extract the gaze ethograms for our behavioral research. We perform another classifier selection at the level of ethogram classification. Finally, we report encouraging results of user behavioral activity recognition experiments carried out over an inhouse dataset.

A frog's eye view: Foundational revelations and future promises

From the mid-19th century until the 1980's, frogs and toads provided important research models for many fundamental questions in visual neuroscience. In the present century, they have been largely neglected. Yet they are animals with highly developed vision, a complex retina built on the basic vertebrate plan, an accessible brain, and an experimentally useful behavioural repertoire. They also offer a rich diversity of species and life histories on a reasonably restricted physiological and evolutionary background. We suggest that important insights may be gained from revisiting classical questions in anurans with state-of-the-art methods. At the input to the system, this especially concerns the molecular evolution of visual pigments and photoreceptors, at the output, the relation between retinal signals, brain processing and behavioural decision-making.

Studying convergent evolution to relate genotype to behavioral phenotype

Neuroscience has a long, rich history in embracing unusual animals for research. Over the past several decades, there has been a technology-driven bottleneck in the species used for neuroscience research. However, an oncoming wave of technologies applicable to many animals hold promise for enabling researchers to address challenging scientific questions that cannot be solved using traditional laboratory animals. Here, we discuss how leveraging the convergent evolution of physiological or behavioral phenotypes can empower research mapping genotype to phenotype interactions. We present two case studies using electric fish and poison frogs and discuss how comparative work can teach us about evolutionary constraint and flexibility at various levels of biological organization. We also offer advice on the potential and pitfalls of establishing novel model systems in neuroscience research. Finally, we end with a discussion on the use of charismatic animals in neuroscience research and their utility in public outreach. Overall, we argue that convergent evolution frameworks can help identify generalizable principles of neuroscience.

An automatic behavior recognition system classifies animal behaviors using movements and their temporal context

Animals can perform complex and purposeful behaviors by executing simpler movements in flexible sequences. It is particularly challenging to analyze behavior sequences when they are highly variable, as is the case in language production, certain types of birdsong and, as in our experiments, flies grooming. High sequence variability necessitates rigorous quantification of large amounts of data to identify organizational principles and temporal structure of such behavior. To cope with large amounts of data, and minimize human effort and subjective bias, researchers often use automatic behavior recognition software. Our standard grooming assay involves coating flies in dust and videotaping them as they groom to remove it. The flies move freely and so perform the same movements in various orientations. As the dust is removed, their appearance changes. These conditions make it difficult to rely on precise body alignment and anatomical landmarks such as eyes or legs and thus present challenges to existing behavior classification software. Human observers use speed, location, and shape of the movements as the diagnostic features of particular grooming actions. We applied this intuition to design a new automatic behavior recognition system (ABRS) based on spatiotemporal features in the video data, heavily weighted for temporal dynamics and invariant to the animal's position and orientation in the scene. We use these spatiotemporal features in two steps of supervised classification that reflect two time-scales at which the behavior is structured. As a proof of principle, we show results from quantification and analysis of a large data set of stimulus-induced fly grooming behaviors that would have been difficult to assess in a smaller dataset of human-annotated ethograms. While we developed and validated this approach to analyze fly grooming behavior, we propose that the strategy of combining alignment-invariant features and multi-timescale analysis may be generally useful for movement-based classification of behavior from video data.

The Future of Gene-Guided Neuroscience Research in Non-Traditional Model Organisms

Natural variations across animals in form, function, and behavior have long been sources of inspiration to scientists. Despite this, experimentalists focusing on the neural bases of behavior have increasingly focused on a select few model species. This consolidation is motivated primarily by the availability of resources and technologies for manipulation in these species. Recent years have witnessed a proliferation of experimental approaches that were developed primarily in traditional model species, but that may in principle be readily applied to any species. High-throughput sequencing, CRISPR gene editing, transgenesis, and other technologies have enabled new insights through their deployment in non-traditional model species. The availability of such approaches changes the calculation of which species to study, particularly when a trait of interest is most readily observed in a non-traditional model organism. If these technologies are widely adopted in many new species, it promises to revolutionize the field of neuroethology.

Co-opting evo-devo concepts for new insights into mechanisms of behavioural diversity

We propose that insights from the field of evolutionary developmental biology (or 'evo-devo') provide a framework for an integrated understanding of the origins of behavioural diversity and its underlying mechanisms. Towards that goal, in this Commentary, we frame key questions in behavioural evolution in terms of molecular, cellular and network-level properties with a focus on the nervous system. In this way, we highlight how mechanistic properties central to evo-devo analyses - such as weak linkage, versatility, exploratory mechanisms, criticality, degeneracy, redundancy and modularity - affect neural circuit function and hence the range of behavioural variation that can be filtered by selection. We outline why comparative studies of molecular and neural systems throughout ontogeny will provide novel insights into diversity in neural circuits and behaviour.

A novel setup for 3D chasing behavior analysis in free flying flies

BACKGROUND

Insects catching prey or mates on the wing perform one of the fastest behaviours observed in nature. Some dipteran flies are aerial acrobats specialized to detect, chase and capture their targets within the blink of an eye. Studies of aerial pursuits and its underlying sensorimotor control have been a long-standing subject of interest in neuroethology research.

NEW METHOD

We designed an actuated dummy target to trigger chasing flights in male blowflies. Our setup generates arbitrary 2D target trajectories in the horizontal plane combining translation up to 1 m/s and angular rotation up to 720°/s.

RESULTS

Using stereovision methods we reconstructed target and pursuer positions every 5 ms with a maximum 3D error of 5 mm. The pursuer's body pitch and yaw angles were resolved within an error range of 6deg. An embedded observation point provides a close-up view of the pursuer's final approach and enables us to measure its body roll angle. We observed banked turns and sideslip which have not been reported for chasing blowflies in the past.

COMPARISON WITH EXISTING METHOD(S)

Previous studies focused on pursuit along circular paths or interception of translating targets while our method allows us to generate more complex target trajectories. Measurements of body orientation in earlier accounts were limited to the heading direction while we extended the analysis to include the full body orientation during pursuit.

CONCLUSIONS

Our setup offers an opportunity to investigate kinematics and governing visual parameters of chasing behaviour in species up to the size of blowflies under a large variety of experimental conditions.

Behavioral analysis of substrate texture preference in a leech, Helobdella austinensis

Leeches in the wild are often found on smooth surfaces, such as vegetation, smooth rocks or human artifacts such as bottles and cans, thus exhibiting what appears to be a "substrate texture preference". Here, we have reproduced this behavior under controlled circumstances, by allowing leeches to step about freely on a range of silicon carbide substrates (sandpaper). To begin to understand the neural mechanisms underlying this texture preference behavior, we have determined relevant parameters of leech behavior both on uniform substrates of varying textures, and in a behavior choice paradigm in which the leech is confronted with a choice between rougher and smoother substrate textures at each step. We tested two non-exclusive mechanisms which could produce substrate texture preference: (1) a Differential Diffusion mechanism, in which a leech is more likely to stop moving on a smooth surface than on a rough one, and (2) a Smoothness Selection mechanism, in which a leech is more likely to attach its front sucker (prerequisite for taking a step) to a smooth surface than to a rough one. We propose that both mechanisms contribute to the texture preference exhibited by leeches.

Encoding lateralization of jump kinematics and eye use in a locust via bio-robotic artifacts

The effect of previous exposure to lateral sensory stimuli in shaping the response to subsequent symmetric stimuli represents an important overlooked issue in neuroethology, with special reference to arthropods. In this research, we investigated the hypothesis to 'programme' jumping escape direction as well as surveillance orientation in young and adult individuals of Locusta migratoria as an adaptive consequence of prior exposure to directional-biased predator approaches generated by a robotic leopard gecko representing Eublepharis macularius The manipulation of the jumping escape direction was successfully achieved in young locusts, although young L. migratoria did not exhibit innately lateralized jumping escapes. Jumping escape direction was also successfully manipulated in adult locusts, which exhibited innate lateralized jumping escape at the individual level. The innate lateralization of each instar of L. migratoria in using a preferential eye during surveillance was not affected by prior lateralized exposure to the robotic gecko. Our results indicate a high plasticity of the escape motor outputs that are occurring almost in real time with the perceived stimuli, making them greatly adaptable and compliant to environmental changes in order to be effective and reliable. In addition, surveillance lateralization innately occurs at population level in each instar of L. migratoria Therefore, its low forgeability by environmental factors would avoid disorganization at swarm level and improve swarm coordination during group tasks. These findings are consistent with the fact that, as in vertebrates, in insects the right hemisphere is specialized in controlling fear and escape functions.

Hunting in archerfish - an ecological perspective on a remarkable combination of skills

Archerfish are well known for using jets of water to dislodge distant aerial prey from twigs or leaves. This Review gives a brief overview of a number of skills that the fish need to secure prey with their shooting technique. Archerfish are opportunistic hunters and, even in the wild, shoot at artificial objects to determine whether these are rewarding. They can detect non-moving targets and use efficient search strategies with characteristics of human visual search. Their learning of how to engage targets can be remarkably efficient and can show impressive degrees of generalization, including learning from observation. In other cases, however, the fish seem unable to learn and it requires some understanding of the ecological and biophysical constraints to appreciate why. The act of shooting has turned out not to be of a simple all-or-none character. Rather, the fish adjust the volume of water fired according to target size and use fine adjustments in the timing of their mouth opening and closing manoeuvre to adjust the hydrodynamic stability of their jets to target distance. As soon as prey is dislodged and starts falling, the fish make rapid and yet sophisticated multi-dimensional decisions to secure their prey against many intraspecific and interspecific competitors. Although it is not known why and how archerfish evolved an ability to shoot in the first place, I suggest that the evolution of shooting has strongly pushed the co-evolution of diverse other skills that are needed to secure a catch.

The Mauthner cell in a fish with top-performance and yet flexibly tuned C-starts. I. Identification and comparative morphology

Archerfish use two powerful C-starts: one to escape threats, the other to secure prey that they have downed with a shot of water. The two C-starts are kinematically equivalent and variable in both phases, and the predictive C-starts - used in hunting - are adjusted in terms of the angle of turning and the final linear speed to where and when their prey will hit the water surface. Presently, nothing is known about the neural circuits that drive the archerfish C-starts. As the starting point for a neuroethological analysis, we first explored the presence and morphology of a pair of Mauthner cells, which are key cells in the teleost fast-start system. We show that archerfish have a typical Mauthner cell in each medullary hemisphere and that these send by far the largest axons down the spinal cord. Stimulation of the spinal cord caused short-latency all-or-none field potentials that could be detected even at the surface of the medulla and that had the Mauthner cell as its only source. The archerfish's Mauthner cell is remarkably similar morphologically to that of equally sized goldfish, except that the archerfish's ventral dendrite is slightly longer and its lateral dendrite thinner. Our data provide the necessary starting point for the dissection of the archerfish fast-start system and of any role potentially played by its Mauthner cell in the two C-start manoeuvres. Moreover, they do not support the recently expressed view that Mauthner cells should be reduced in animals with highly variable fast-start manoeuvres.

The Mauthner cell in a fish with top-performance and yet flexibly tuned C-starts. II. Physiology

The parallel occurrence in archerfish of fine-tuned and yet powerful predictive C-starts as well as of kinematically identical escape C-starts makes archerfish an interesting system to test hypotheses on the roles played by the Mauthner cells, a pair of giant reticulospinal neurons. In this study, we show that the archerfish Mauthner cell shares all hallmark physiological properties with that of goldfish. Visual and acoustic inputs are received by the ventral and lateral dendrite, respectively, and cause complex postsynaptic potentials (PSPs) even in surgically anaesthetised fish. PSP shape did not indicate major differences between the species, but simple light flashes caused larger PSPs in archerfish, often driving the cell to fire an action potential. Probing archerfish in the classical tests for feedback inhibition, established in the Mauthner-associated networks in goldfish, revealed no differences between the two species, including the indications for electrical and chemical synaptic components. Also, the established hallmark experiments on feed-forward inhibition showed no differences between the goldfish and archerfish Mauthner system. Extending these experiments to visual stimuli also failed to detect any differences between the two species and suggested that acoustical and visual input cause feed-forward inhibition, the magnitude, time course and duration of which match that of the respective PSPs in both archerfish and goldfish. Our findings question simple views on the role of the Mauthner cell and suggest that the archerfish Mauthner cell should be a good system to explore the function of these giant neurons in more sophisticated C-start behaviours.

Deep facial analysis: A new phase I epilepsy evaluation using computer vision

Semiology observation and characterization play a major role in the presurgical evaluation of epilepsy. However, the interpretation of patient movements has subjective and intrinsic challenges. In this paper, we develop approaches to attempt to automatically extract and classify semiological patterns from facial expressions. We address limitations of existing computer-based analytical approaches of epilepsy monitoring, where facial movements have largely been ignored. This is an area that has seen limited advances in the literature. Inspired by recent advances in deep learning, we propose two deep learning models, landmark-based and region-based, to quantitatively identify changes in facial semiology in patients with mesial temporal lobe epilepsy (MTLE) from spontaneous expressions during phase I monitoring. A dataset has been collected from the Mater Advanced Epilepsy Unit (Brisbane, Australia) and is used to evaluate our proposed approach. Our experiments show that a landmark-based approach achieves promising results in analyzing facial semiology, where movements can be effectively marked and tracked when there is a frontal face on visualization. However, the region-based counterpart with spatiotemporal features achieves more accurate results when confronted with extreme head positions. A multifold cross-validation of the region-based approach exhibited an average test accuracy of 95.19% and an average AUC of 0.98 of the ROC curve. Conversely, a leave-one-subject-out cross-validation scheme for the same approach reveals a reduction in accuracy for the model as it is affected by data limitations and achieves an average test accuracy of 50.85%. Overall, the proposed deep learning models have shown promise in quantifying ictal facial movements in patients with MTLE. In turn, this may serve to enhance the automated presurgical epilepsy evaluation by allowing for standardization, mitigating bias, and assessing key features. The computer-aided diagnosis may help to support clinical decision-making and prevent erroneous localization and surgery.

Intense olfactory stimulation blocks seizures in an experimental model of epilepsy

There are reports of patients whose epileptic seizures are prevented by means of olfactory stimulation. Similar findings were described in animal models of epilepsy, such as the electrical kindling of amygdala, where olfactory stimulation with toluene (TOL) suppressed seizures in most rats, even when the stimuli were 20% above the threshold to evoke seizures in already kindled animals. The Wistar Audiogenic Rat (WAR) strain is a model of tonic-clonic seizures induced by acute acoustic stimulation, although it also expresses limbic seizures when repeated acoustic stimulation occurs - a process known as audiogenic kindling (AK). The aim of this study was to evaluate whether or not the olfactory stimulation with TOL would interfere on the behavioral expression of brainstem (acute) and limbic (chronic) seizures in the WAR strain. For this, animals were exposed to TOL or saline (SAL) and subsequently exposed to acoustic stimulation in two conditions that generated: I) acute audiogenic seizures (only one acoustic stimulus, without previous seizure experience before of the odor test) and II) after AK (20 acoustic stimuli [2 daily] before of the protocol test). We observed a decrease in the seizure severity index of animals exposed only to TOL in both conditions, with TOL presented 20s before the acoustic stimulation in both protocols. These findings were confirmed by behavioral sequential analysis (neuroethology), which clearly indicated an exacerbation of clusters of specific behaviors such as exploration and grooming (self-cleaning), as well as significant decrease in the expression of brainstem and limbic seizures in response to TOL. Thus, these data demonstrate that TOL, a strong olfactory stimulus, has anticonvulsant properties, detected by the decrease of acute and AK seizures in WARs.

Transcriptomic analysis of instinctive and learned reward-related behaviors in honey bees

We used transcriptomics to compare instinctive and learned, reward-based honey bee behaviors with similar spatio-temporal components: mating flights by males (drones) and time-trained foraging flights by females (workers), respectively. Genome-wide gene expression profiling via RNA sequencing was performed on the mushroom bodies, a region of the brain known for multi-modal sensory integration and responsive to various types of reward. Differentially expressed genes (DEGs) associated with the onset of mating (623 genes) were enriched for the gene ontology (GO) categories of Transcription, Unfolded Protein Binding, Post-embryonic Development, and Neuron Differentiation. DEGs associated with the onset of foraging (473) were enriched for Lipid Transport, Regulation of Programmed Cell Death, and Actin Cytoskeleton Organization. These results demonstrate that there are fundamental molecular differences between similar instinctive and learned behaviors. In addition, there were 166 genes with strong similarities in expression across the two behaviors - a statistically significant overlap in gene expression, also seen in Weighted Gene Co-Expression Network Analysis. This finding indicates that similar instinctive and learned behaviors also share common molecular architecture. This common set of DEGs was enriched for Regulation of RNA Metabolic Process, Transcription Factor Activity, and Response to Ecdysone. These findings provide a starting point for better understanding the relationship between instincts and learned behaviors. In addition, because bees collect food for their colony rather than for themselves, these results also support the idea that altruistic behavior relies, in part, on elements of brain reward systems associated with selfish behavior.

The planarian TRPA1 homolog mediates extraocular behavioral responses to near-ultraviolet light

Although light is most commonly thought of as a visual cue, many animals possess mechanisms to detect light outside of the eye for various functions, including predator avoidance, circadian rhythms, phototaxis and migration. Here we confirm that planarians (like Caenorhabditis elegans, leeches and Drosophila larvae) are capable of detecting and responding to light using extraocular photoreception. We found that, when either eyeless or decapitated worms were exposed to near-ultraviolet (near-UV) light, intense wild-type photophobic behaviors were still observed. Our data also revealed that behavioral responses to green wavelengths were mediated by ocular mechanisms, whereas near-UV responses were driven by extraocular mechanisms. As part of a candidate screen to uncover the genetic basis of extraocular photoreception in the planarian species Schmidtea mediterranea, we identified a potential role for a homolog of the transient receptor potential channel A1 (TRPA1) in mediating behavioral responses to extraocular light cues. RNA interference (RNAi) to Smed-TrpA resulted in worms that lacked extraocular photophobic responses to near-UV light, a mechanism previously only identified in Drosophila These data show that the planarian TRPA1 homolog is required for planarian extraocular-light avoidance and may represent a potential ancestral function of this gene. TRPA1 is an evolutionarily conserved detector of temperature and chemical irritants, including reactive oxygen species that are byproducts of UV-light exposure. Our results suggest that planarians possess extraocular photoreception and display an unconventional TRPA1-mediated photophobic response to near-UV light.

Pharmacological and neuroethological study of the acute and chronic effects of lamotrigine in the genetic audiogenic seizure hamster (GASH:Sal)

The present study aimed to investigate the behavioral and anticonvulsant effects of lamotrigine (LTG) on the genetic audiogenic seizure hamster (GASH:Sal), an animal model of audiogenic seizure that is in the validation process. To evaluate the efficiency of acute and chronic treatments with LTG, GASH:Sals were treated with LTG either acutely via intraperitoneal injection (5-20mg/kg) or chronically via oral administration (20-25mg/kg/day). Their behavior was assessed via neuroethological analysis, and the anticonvulsant effect of LTG was evaluated based on the appearance and the severity of seizures. The results showed that acute administration of LTG exerts an anticonvulsant effect at the lowest dose tested (5mg/kg) and that chronic oral LTG treatment exerts an anticonvulsant effect at a dose of 20-25mg/kg/day. Furthermore, LTG treatment induced a low rate of secondary adverse effects. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".