Outsourced hearing in an orb-weaving spider that uses its web as an auditory sensor.

SignificanceThe sense of hearing in all known animals relies on possessing auditory organs that are made up of cellular tissues and constrained by body sizes. We show that hearing in the orb-weaving spider is functionally outsourced to its extended phenotype, the proteinaceous self-manufactured web, and hence processes behavioral controllability. This finding opens new perspectives on animal extended cognition and hearing-the outsourcing and supersizing of auditory function in spiders. This study calls for reinvestigation of the remarkable evolutionary ecology and sensory ecology in spiders-one of the oldest land animals. The sensory modality of outsourced hearing provides a unique model for studying extended and regenerative sensing and presents new design features for inspiring novel acoustic flow detectors.

A variable refractory period increases collective performance in noisy environments.

Synchronized oscillations are found in all living systems, from cellsto ecosystems and on varying time scales. A generic principlebehind the production of oscillations involves a delay in theresponse of one entity to stimulations from the others in the sys-tem. Communication among entities is required for the emergenceof synchronization, but its efficacy can be impaired by surroundingnoise. In the social spiderAnelosimus eximius, individuals coordi-nate their activity to catch large prey that are otherwise inaccessi-ble to solitary hunters. When hunting in groups, dozens of spidersmove rhythmically toward their prey by synchronizing movingand stopping phases. We proposed a mechanistic model imple-menting individual behavioral rules, all derived fromfield experi-ments, to elucidate the underlying principles of synchronization.We showed that the emergence of oscillations in spiders involvesa refractory state, the duration of which depends on the relativeintensity of prey versus conspecific signals. Thisflexible behaviorallows individuals to rapidly adapt to variations in their vibrationallandscapes. Exploring the model reveals that the benefits of syn-chronization resulting from improved accuracy in prey detectionand reduced latency to capture prey more than offset the cost ofthe delay associated with immobility phases. Overall, our studyshows that a refractory period whose duration is variable anddependent on information accessible to all entities in the systemcontributes to the emergence of self-organized oscillations innoisy environments. Ourfindings may inspire the design of artifi-cial systems requiring fast andflexible synchronization betweentheir components.

FGF signalling is involved in cumulus migration in the common house spider Parasteatoda tepidariorum.

Cell migration is a fundamental component during the development of most multicellular organisms. In the early spider embryo, the collective migration of signalling cells, known as the cumulus, is required to set the dorsoventral body axis. Here, we show that FGF signalling plays an important role during cumulus migration in the spider Parasteatoda tepidariorum. Spider embryos with reduced FGF signalling show reduced or absent cumulus migration and display dorsoventral patterning defects. Our study reveals that the transcription factor Ets4 regulates the expression of several FGF signalling components in the cumulus. In conjunction with a previous study, we show that the expression of fgf8 in the germ-disc is regulated via the Hedgehog signalling pathway. We also demonstrate that FGF signalling influences the BMP signalling pathway activity in the region around cumulus cells. Finally, we show that FGFR signalling might also influence cumulus migration in basally branching spiders and we propose that fgf8 might act as a chemo-attractant to guide cumulus cells towards the future dorsal pole of the spider embryo.

Dissecting the contributions of membrane affinity and bivalency of the spider venom protein DkTx to its sustained mode of TRPV1 activation.

The spider venom protein, double-knot toxin (DkTx), partitions into the cellular membrane and binds bivalently to the pain-sensing ion channel, TRPV1, triggering long-lasting channel activation. In contrast, its monovalent single knots membrane partition poorly and invoke rapidly reversible TRPV1 activation. To discern the contributions of the bivalency and membrane affinity of DkTx to its sustained mode of action, here, we developed diverse toxin variants including those containing truncated linkers between individual knots, precluding bivalent binding. Additionally, by appending the single-knot domains to the Kv2.1 channel-targeting toxin, SGTx, we created monovalent double-knot proteins that demonstrated higher membrane affinity and more sustained TRPV1 activation than the single-knots. We also produced hyper-membrane affinity-possessing tetra-knot proteins, (DkTx)2 and DkTx-(SGTx)2, that demonstrated longer-lasting TRPV1 activation than DkTx, establishing the central role of the membrane affinity of DkTx in endowing it with its sustained TRPV1 activation properties. These results suggest that high membrane affinity-possessing TRPV1 agonists can potentially serve as long-acting analgesics.

Single-cell RNA sequencing of mid-to-late stage spider embryos: new insights into spider development.

BACKGROUND: The common house spider Parasteatoda tepidariorum represents an emerging new model organism of arthropod evolutionary and developmental (EvoDevo) studies. Recent technical advances have resulted in the first single-cell sequencing (SCS) data on this species allowing deeper insights to be gained into its early development, but mid-to-late stage embryos were not included in these pioneering studies. RESULTS: Therefore, we performed SCS on mid-to-late stage embryos of Parasteatoda and characterized resulting cell clusters by means of in-silico analysis (comparison of key markers of each cluster with previously published information on these genes). In-silico prediction of the nature of each cluster was then tested/verified by means of additional in-situ hybridization experiments with additional markers of each cluster. CONCLUSIONS: Our data show that SCS data reliably group cells with similar genetic fingerprints into more or less distinct clusters, and thus allows identification of developing cell types on a broader level, such as the distinction of ectodermal, mesodermal and endodermal cell lineages, as well as the identification of distinct developing tissues such as subtypes of nervous tissue cells, the developing heart, or the ventral sulcus (VS). In comparison with recent other SCS studies on the same species, our data represent later developmental stages, and thus provide insights into different stages of developing cell types and tissues such as differentiating neurons and the VS that are only present at these later stages.

Foraging rates from metabarcoding: Predators have reduced functional responses in wild, diverse prey communities.

Functional responses describe foraging rates across prey densities and underlie many fundamental ecological processes. Most functional response knowledge comes from simplified lab experiments, but we do not know whether these experiments accurately represent foraging in nature. In addition, the difficulty of conducting multispecies functional response experiments means that it is unclear whether interaction strengths are weakened in the presence of multiple prey types. We developed a novel method to estimate wild predators' foraging rates from metabarcoding data and use this method to present functional responses for wild wolf spiders foraging on 27 prey families. These field functional responses were considerably reduced compared to lab functional responses. We further find that foraging is sometimes increased in the presence of other prey types, contrary to expectations. Our novel method for estimating field foraging rates will allow researchers to determine functional responses for wild predators and address long-standing questions about foraging in nature.

Evolution of the Spider Homeobox Gene Repertoire by Tandem and Whole Genome Duplication.

Gene duplication generates new genetic material that can contribute to the evolution of gene regulatory networks and phenotypes. Duplicated genes can undergo subfunctionalization to partition ancestral functions and/or neofunctionalization to assume a new function. We previously found there had been a whole genome duplication (WGD) in an ancestor of arachnopulmonates, the lineage including spiders and scorpions but excluding other arachnids like mites, ticks, and harvestmen. This WGD was evidenced by many duplicated homeobox genes, including two Hox clusters, in spiders. However, it was unclear which homeobox paralogues originated by WGD versus smaller-scale events such as tandem duplications. Understanding this is a key to determining the contribution of the WGD to arachnopulmonate genome evolution. Here we characterized the distribution of duplicated homeobox genes across eight chromosome-level spider genomes. We found that most duplicated homeobox genes in spiders are consistent with an origin by WGD. We also found two copies of conserved homeobox gene clusters, including the Hox, NK, HRO, Irx, and SINE clusters, in all eight species. Consistently, we observed one copy of each cluster was degenerated in terms of gene content and organization while the other remained more intact. Focussing on the NK cluster, we found evidence for regulatory subfunctionalization between the duplicated NK genes in the spider Parasteatoda tepidariorum compared to their single-copy orthologues in the harvestman Phalangium opilio. Our study provides new insights into the relative contributions of multiple modes of duplication to the homeobox gene repertoire during the evolution of spiders and the function of NK genes.

Sequence analysis, homology modeling, tissue expression, and potential functions of seven putative acetylcholinesterases in the spider Cupiennius salei.

Acetylcholine esterases (AChEs) are essential enzymes in cholinergic synapses, terminating neurotransmission by hydrolysing acetylcholine. While membrane bound AChEs at synaptic clefts efficiently perform this task, soluble AChEs are less stable and effective, but function over broader areas. In vertebrates, a single gene produces alternatively spliced forms of AChE, whereas invertebrates often have multiple genes, producing both enzyme types. Despite their significance as pesticide targets, the physiological roles of invertebrate AChEs remain unclear. Here, we characterized seven putative AChEs in the wandering spider, Cupiennius salei, a model species for neurophysiological studies. Sequence analyses and homology modeling predicted CsAChE7 as the sole stable, membrane-bound enzyme functioning at synaptic clefts, while the others are likely soluble enzymes. In situ hybridization of sections from the spider's nervous system revealed CsAChE7 transcripts co-localizing with choline acetyltransferase in cells that also exhibited AChE activity. CsAChE7 transcripts were also found in rapidly adapting mechanosensory neurons, suggesting a role in precise and transient activation of postsynaptic cells, contrasting with slowly adapting, also cholinergic, neurons expressing only soluble AChEs, which allow prolonged activation of postsynaptic cells. These findings suggest that cholinergic transmission is influenced not only by postsynaptic receptors but also by the enzymatic properties regulating acetylcholine clearance. We also show that acetylcholine is a crucial neurotransmitter in the spider's visual system and sensory and motor pathways, but absent in excitatory motor neurons at neuromuscular junctions, consistent with other arthropods. Our findings on sequence structures may have implications for the development of neurological drugs and pesticides.

Decoding plant-induced transcriptomic variability and consistency in two related polyphagous mites differing in host ranges.

The diet breadth of generalist herbivores when compared to specialists tends to be associated with greater transcriptional plasticity. Here, we consider whether it may also contribute to variation in host range among two generalists with different levels of polyphagy. We examined two related polyphagous spider mites with different host ranges, Tetranychus urticae (1200 plants) and Tetranychus truncatus (90 plants). Data from multiple populations of both species domesticated on common beans and transferred to new plant hosts (cotton, cucumber, eggplant) were used to investigate transcriptional plasticity relative to population-based variation in gene expression. Compared to T. truncatus, T. urticae exhibited much higher transcriptional plasticity. Populations of this species also showed much more variable expression regulation in response to a plant host, particularly for genes related to detoxification, transport, and transcriptional factors. In response to the different plant hosts, both polyphagous species showed enriched processes of drug/xenobiotics metabolism, with T. urticae orchestrating a relatively broader array of biological pathways. Through co-expression network analysis, we identified gene modules associated with host plant response, revealing shared hub genes primarily involved in detoxification metabolism when both mites fed on the same plants. After silencing a shared hub CYP gene related to eggplant exposure, the performance of both species on the original bean host improved, but the fecundity of T. truncatus decreased when feeding on eggplant. The extensive transcriptomic variation shown by T. urticae might serve as a potential compensatory mechanism for a deficiency of hub genes in this species. This research points to nuanced differences in transcriptomic variability between generalist herbivores.

Glycosylation mode of phloretin affects the morphology and stress resistance of apple plant.

Phloretin has different glycosylation modes in plants. Phlorizin (phloretin 2'-O-glucoside) is one of the glycosylation products of phloretin, and accumulates abundantly in apple plants. However, it is still unclear whether phlorizin is more beneficial for apple plants compared with other glycosylation products of phloretin. We created transgenic apple plants with different glycosylation modes of phloretin. In transgenic plants, the accumulation of phlorizin was partly replaced by that of trilobatin (phloretin 4'-O-glucoside) or phloretin 3',5'-di-C-glycoside. Compared with wild type, transgenic plants with less phlorizin showed dwarf phenotype, larger stomatal size, higher stomatal density and less tolerance to drought stress. Transcriptome and phytohormones assay indicate that phlorizin might regulate stomatal development and behaviour via controlling auxin and abscisic acid signalling pathways as well as carbonic anhydrase expressions. Transgenic apple plants with less phlorizin also showed less resistance to spider mites. Apple plants may hydrolyse phlorizin to produce phloretin, but cannot hydrolyse trilobatin or phloretin 3',5'-di-C-glycoside. Compared with its glycosylation products, phloretin is more toxic to spider mites. These results suggest that the glycosylation of phloretin to produce phlorizin is the optimal glycosylation mode in apple plants, and plays an important role in apple resistance to stresses.

Facilitating taxonomy and phylogenetics: An informative and cost-effective protocol integrating long amplicon PCRs and third-generation sequencing.

Phylogenetic inference has become a standard technique in integrative taxonomy and systematics, as well as in biogeography and ecology. DNA barcodes are often used for phylogenetic inference, despite being strongly limited due to their low number of informative sites. Also, because current DNA barcodes are based on a fraction of a single, fast-evolving gene, they are highly unsuitable for resolving deeper phylogenetic relationships due to saturation. In recent years, methods that analyse hundreds and thousands of loci at once have improved the resolution of the Tree of Life, but these methods require resources, experience and molecular laboratories that most taxonomists do not have. This paper introduces a PCR-based protocol that produces long amplicons of both slow- and fast-evolving unlinked mitochondrial and nuclear gene regions, which can be sequenced by the affordable and portable ONT MinION platform with low infrastructure or funding requirements. As a proof of concept, we inferred a phylogeny of a sample of 63 spider species from 20 families using our proposed protocol. The results were overall consistent with the results from approaches based on hundreds and thousands of loci, while requiring just a fraction of the cost and labour of such approaches, making our protocol accessible to taxonomists worldwide.

A consequential one-night stand: Episodic historical hybridization leads to mitochondrial takeover in sympatric desert ant-eating spiders.

Disentangling the genomic intricacies underlying speciation and the causes of discordance between sources of evidence can offer remarkable insights into evolutionary dynamics. The ant-eating spider Zodarion nitidum, found across the Middle East and Egypt, displays yellowish and blackish morphs that co-occur sympatrically. These morphs additionally differ in behavioral and physiological features and show complete pre-mating reproductive isolation. In contrast, they possess similar sexual features and lack distinct differences in their mitochondrial DNA. We analyzed both Z. nitidum morphs and outgroups using genome-wide and additional mitochondrial DNA data. The genomic evidence indicated that Yellow and Black are reciprocally independent lineages without signs of recent admixture. Interestingly, the sister group of Yellow is not Black but Z. luctuosum, a morphologically distinct species. Genomic gene flow analyses pinpointed an asymmetric nuclear introgression event, with Yellow contributing nearly 5 % of its genome to Black roughly 320,000 years ago, intriguingly aligning with the independently estimated origin of the mitochondrial DNA of Black. We conclude that the blackish and yellowish morphs of Z. nitidum are long-diverged distinct species, and that the ancient and modest genomic introgression event registered resulted in a complete mitochondrial takeover of Black by Yellow. This investigation underscores the profound long-term effects that even modest hybridization events can have on the genome of organisms. It also exemplifies the utility of phylogenetic networks for estimating historical events and how integrating independent lines of evidence can increase the reliability of such estimations.

In vitro and in vivo investigation of Argiope bruennichi spider silk-based novel biomaterial for medical use.

As a natural and biocompatible material with high strength and flexibility, spider silk is frequently used in biomedical studies. In this study, the availability of Argiope bruennichi spider silk as a surgical suture material was investigated. The effects of spider silk-based and commercial sutures, with and without Aloe vera coating, on wound healing were evaluated by a rat dorsal skin flap model, postoperatively (7th and 14th days). Biochemical, hematological, histological, immunohistochemical, small angle x-ray scattering (SAXS) analyses and mechanical tests were performed. A. bruennichi silk did not show any cytotoxic effect on the L929 cell line according to MTT and LDH assays, in vitro. The silk materials did not cause any allergic reaction, infection, or systemic effect in rats according to hematological and biochemical analyses. A. bruennichi spider silk group showed a similar healing response to commercial sutures. SAXS analysis showed that the 14th-day applications of A. bruennichi spider silk and A. vera coated commercial suture groups have comparable structural results with control group. In conclusion, A. bruennichi spider silk is biocompatible in line with the parameters examined and shows a healing response similar to the commercial sutures commonly used in the skin.

Membrane-based inverse-transition purification facilitates a rapid isolation of various spider-silk elastin-like polypeptide fusion proteins from extracts of transgenic tobacco.

Plants can produce complex pharmaceutical and technical proteins. Spider silk proteins are one example of the latter and can be used, for example, as compounds for high-performance textiles or wound dressings. If genetically fused to elastin-like polypeptides (ELPs), the silk proteins can be reversibly precipitated from clarified plant extracts at moderate temperatures of ~ 30 °C together with salt concentrations > 1.5 M, which simplifies purification and thus reduces costs. However, the technologies developed around this mechanism rely on a repeated cycling between soluble and aggregated state to remove plant host cell impurities, which increase process time and buffer consumption. Additionally, ELPs are difficult to detect using conventional staining methods, which hinders the analysis of unit operation performance and process development. Here, we have first developed a surface plasmon resonance (SPR) spectroscopy-based assay to quantity ELP fusion proteins. Then we tested different filters to prepare clarified plant extract with > 50% recovery of spider silk ELP fusion proteins. Finally, we established a membrane-based purification method that does not require cycling between soluble and aggregated ELP state but operates similar to an ultrafiltration/diafiltration device. Using a data-driven design of experiments (DoE) approach to characterize the system of reversible ELP precipitation we found that membranes with pore sizes up to 1.2 µm and concentrations of 2-3 M sodium chloride facilitate step a recovery close to 100% and purities of > 90%. The system can thus be useful for the purification of ELP-tagged proteins produced in plants and other hosts.

Eye-specific detection and a multi-eye integration model of biological motion perception.

'Biological motion' refers to the distinctive kinematics observed in many living organisms, where visually perceivable points on the animal move at fixed distances from each other. Across the animal kingdom, many species have developed specialized visual circuitry to recognize such biological motion and to discriminate it from other patterns. Recently, this ability has been observed in the distributed visual system of jumping spiders. These eight-eyed animals use six eyes to perceive motion, while the remaining two (the principal anterior medial eyes) are shifted across the visual scene to further inspect detected objects. When presented with a biologically moving stimulus and a random one, jumping spiders turn to face the latter, clearly demonstrating the ability to discriminate between them. However, it remains unclear whether the principal eyes are necessary for this behavior, whether all secondary eyes can perform this discrimination, or whether a single eye-pair is specialized for this task. Here, we systematically tested the ability of jumping spiders to discriminate between biological and random visual stimuli by testing each eye-pair alone. Spiders were able to discriminate stimuli only when the anterior lateral eyes were unblocked, and performed at chance levels in other configurations. Interestingly, spiders showed a preference for biological motion over random stimuli - unlike in past work. We therefore propose a new model describing how specialization of the anterior lateral eyes for detecting biological motion contributes to multi-eye integration in this system. This integration generates more complex behavior through the combination of simple, single-eye responses. We posit that this in-built modularity may be a solution to the limited resources of these invertebrates' brains, constituting a novel approach to visual processing.

The kinematics of amblypygid (Arachnida) pedipalps during predation: extreme elongation in raptorial appendages does not result in a proportionate increase in reach and closing speed.

The link between form and function is key to understanding the evolution of unique and/or extreme morphologies. Amblypygids, or whip spiders, are arachnids that often have highly elongated spined pedipalps. These limbs are used to strike at, and secure, prey before processing by the chelicerae. Amblypygi pedipalps are multifunctional, however, being used in courtship and contest, and vary greatly in form between species. Increased pedipalp length may improve performance during prey capture, but length could also be influenced by factors including territorial contest and sexual selection. Here, for the first time, we used high-speed videography and manual tracking to investigate kinematic differences in prey capture between amblypygid species. Across six morphologically diverse species, spanning four genera and two families, we created a total dataset of 86 trials (9-20 per species). Prey capture kinematics varied considerably between species, with differences being expressed in pedipalp joint angle ranges. In particular, maximum reach ratio did not remain constant with total pedipalp length, as geometric scaling would predict, but decreased with longer pedipalps. This suggests that taxa with the most elongated pedipalps do not deploy their potential length advantage to proportionally increase reach. Therefore, a simple mechanical explanation of increased reach does not sufficiently explain pedipalp elongation. We propose other factors to help explain this phenomenon, such as social interactions or sexual selection, which would produce an evolutionary trade-off in pedipalp length between prey capture performance and other behavioural and/or anatomical pressures.

Independence and synergy of spatial attention in the two visual systems of jumping spiders.

By selectively focusing on a specific portion of the environment, animals can solve the problem of information overload, toning down irrelevant inputs and concentrating only on the relevant ones. This may be of particular relevance for animals such as the jumping spider, which possess a wide visual field of almost 360° and thus could benefit from a low-cost system for sharpening attention. Jumping spiders have a modular visual system composed of four pairs of eyes, of which only the two frontal eyes (i.e., AMEs) are motile, whereas the other secondary pairs remain immobile. We hypothesized that jumping spiders can exploit both principal and secondary eyes for stimulus detection and attentional shift, with the two systems working synergistically. In Experiment 1 we investigated AMEs' attentional responses following a spatial cue presented to the secondary eyes. In Experiment 2, we tested for enhanced attention in the secondary eyes' visual field congruent with the direction of the AMEs' focus. In both experiments, we observed that animals were faster and more accurate in detecting a target when it appeared in a direction opposite to that of the initial cue. In contrast with our initial hypothesis, these results would suggest that attention is segregated across eyes, with each system working on compensating the other by attending to different spatial locations.

Serial visual reversal learning in captive black-handed spider monkeys, Ateles geoffroyi.

Recent research suggests that socio-ecological factors such as dietary specialization and social complexity may be drivers of advanced cognitive skills among primates. Therefore, we assessed the ability of 12 black-handed spider monkeys (Ateles geoffroyi), a highly frugivorous platyrrhine primate with strong fission-fusion dynamics, to succeed in a serial visual reversal learning task. Using a two-alternative choice paradigm we first trained the animals to reliably choose a rewarded visual stimulus over a non-rewarded one. Upon reaching a pre-set learning criterion we then switched the reward values of the two stimuli and assessed if and how quickly the animals learned to reverse their choices, again to a pre-set learning criterion. This stimulus reversal procedure was then continued for a total of 80 sessions of 10 trials each. We found that the spider monkeys quickly learned to reliably discriminate between two simultaneously presented visual stimuli, that they succeeded in a visual reversal learning task, and that they displayed an increase in learning speed across consecutive reversals, suggesting that they are capable of serial reversal learning-set formation with visual cues. The fastest-learning individual completed five reversals within the 80 sessions. The spider monkeys outperformed most other primate and nonprimate mammal species tested so far on this type of cognitive task, including chimpanzees, with regard to their learning speed in both the initial learning task and in the first reversal task, suggesting a high degree of behavioral flexibility and inhibitory control. Our findings support the notion that socio-ecological factors such as dietary specialization and social complexity foster advanced cognitive skills in primates.

Sustained metabolic benefits of ΔTRTX-Ac1, a tarantula venom-derived peptide, when administered together with exenatide in high-fat fed mice.

AIM: The aim of the present study was to assess the long-term therapeutic efficacy of a recently discovered 28 amino acid peptide, Δ-theraphotoxin-Ac1 (Δ-TRTX-Ac1), originally isolated from venom of the Aphonopelma chalcodes tarantula. Δ-TRTX-Ac has previously been shown to improve pancreatic beta-cell function and suppress appetite. MATERIALS AND METHODS: Δ-TRTX-Ac1 was administered twice daily in high-fat fed (HFF) mice with streptozotocin (STZ)-induced insulin deficiency, namely HFF/STZ mice, for 28 days both alone and in combination with the venom-derived glucagon-like peptide-1 (GLP-1) mimetic, exenatide. RESULTS: Initial pharmacokinetic profiling of ΔTRTX-Ac1 revealed a plasma half-life of 2 h in mice, with ΔTRTX-Ac1 also evidenced in the pancreas 12 h post-injection. Accordingly, HFF-STZ mice received twice-daily injections of Δ-TRTX-Ac1, exenatide or a combination of both peptides for 28 days. As anticipated, HFF/STZ mice presented with hyperglycaemia, impaired glucose tolerance, decreased plasma and pancreatic insulin and disturbed pancreatic islet morphology. Administration of ΔTRTX-Ac1 reduced body weight, improved glucose tolerance and augmented pancreatic insulin content while decreasing glucagon content. Exenatide had similar benefits on body weight and pancreatic hormone content while also reducing circulating glucose. ΔTRTX-Ac1 decreased energy expenditure on day 28 whereas exenatide had no impact. All treatment regimens restored pancreatic islet and beta-cell area towards lean control levels, which was linked to significantly elevated beta-cell proliferation rates. In terms of benefits of combined ΔTRTX-Ac1 and exenatide treatment over individual agents, there was augmentation of glucose tolerance and ambulatory activity with combination therapy, and these mice presented with increased pancreatic glucagon. CONCLUSION: These data highlight the therapeutic promise of ΔTRTX-Ac1 for diabetes, with suggestion that benefits could be enhanced through combined administration with exenatide.

Expectancy and attention bias to spiders: Dissecting anticipation and allocation processes using ERPs.

The current registered report focused on the temporal dynamics of the relationship between expectancy and attention toward threat, to better understand the mechanisms underlying the prioritization of threat detection over expectancy. In the current event-related potentials experiment, a-priori expectancy was manipulated, and attention bias was measured, using a well-validated paradigm. A visual search array was presented, with one of two targets: spiders (threatening) or birds (neutral). A verbal cue stating the likelihood of encountering a target preceded the array, creating congruent and incongruent trials. Following cue presentation, preparatory processes were examined using the contingent negative variation (CNV) component. Following target presentation, two components were measured: early posterior negativity (EPN) and late positive potential (LPP), reflecting early and late stages of natural selective attention toward emotional stimuli, respectively. Behaviorally, spiders were found faster than birds, and congruency effects emerged for both targets. For the CNV, a non-significant trend of more negative amplitudes following spider cues emerged. As expected, EPN and LPP amplitudes were larger for spider targets compared to bird targets. Data-driven, exploratory, topographical analyses revealed different patterns of activation for bird cues compared to spider cues. Furthermore, 400-500 ms post-target, a congruency effect was revealed only for bird targets. Together, these results demonstrate that while expectancy for spider appearance is evident in differential neural preparation, the actual appearance of spider target overrides this expectancy effect and only in later stages of processing does the cueing effect come again into play.