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Results for “animal behavior and cognition”

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bioRxiv2018

Conditioned increase of locomotor activity induced by haloperidol

Dopamine antagonist drugs have profound effects on locomotor activity. In particular, the administration of the D2 antagonist haloperidol produces a state that is similar to catalepsy. In order to confirm whether the modulation of the dopaminergic activity produced by haloperidol can act as an unconditioned stimulus, we carried out two experiments in which the administration of haloperidol was repeatedly paired with the presence of distinctive contextual cues that served as a Conditioned Stimulus. Paradoxically, the results revealed a dose-dependent increase in locomotor activity following conditioning with dopamine antagonist (Experiments 1) that was susceptible of extinction when the conditioned stimulus was presented repeatedly by itself after conditioning (Experiment 2). These data are interpreted from an associative perspective, considering them as a result of a classical conditioning process.

animal behavior and cognition↗

bioRxiv2018

Angular Substrate Preference and Molting Behavior of the Giant River Prawn, Macrobrachium rosenbergii and its Implications for Cannibalism Management

The Giant River Prawn is an important commercial species from southeastern Asia and has a large global market. It has a complex life cycle in which it undergoes several molting sequences. Many arthropods require firm perches on which they can perform ecdysis. We investigated preference for substrate slope and its influence on ecdysis. We discovered that prawns occupy horizontal surfaces more frequently than others, but during pre-molt and molt stages, they shift their habitat use to non-horizontally sloped surfaces. Here, they will flex their shell and later molt. We recommend modification of cannibalism management in commercial facilities by providing sufficient vertical (strongly preferred) or high-sloped (greater than 30 degrees) surfaces to facilitate ecdysis, while providing much horizontal space for foraging and other activities. This should create habitat separation between foraging and highly susceptible freshly-molted prawns, thus leading to reduced cannibalism-related mortality.\n\nFundingThis work was supported by the USDA Evans Allen Program at Langston University, Project Number USDA-NIFA-OKLUMCCALLUM2017.\n\nDisclosure statementWe acknowledge that there is no financial interest or benefit that has arisen from the direct applications of our research.

animal behavior and cognition↗

bioRxiv2018

Mechanics of exploration in Drosophila melanogaster

The Drosophila larva executes a stereotypical exploratory routine that appears to consist of stochastic alternation between straight peristaltic crawling and reorientation events through lateral bending. We present a model of larval mechanics for axial and transverse motion over a planar substrate, and use it to develop a simple, reflexive neuromuscular model from physical principles. In the absence of damping and driving, the mechanics of the body produces axial travelling waves, lateral oscillations, and unpredictable, chaotic deformations. The neuromuscular system counteracts friction to recover these motion patterns, giving rise to forward and backward peristalsis in addition to turning. The model produces spontaneous exploration, even though the model nervous system has no intrinsic pattern generating or decision making ability, and neither senses nor drives bending motions. Ultimately, our model suggests a novel view of larval exploration as a deterministic superdiffusion process which is mechanistically grounded in the chaotic mechanics of the body.

animal behavior and cognition↗

bioRxiv2018

Bats adjust temporal features of echolocation calls but not those of communication calls in response to traffic noise

Summary statementThis study reveals the impact of anthropogenic noise on spectrally distinct vocalizations and the limitations of the acoustic masking hypothesis to explain the vocal response of bats to chronic noise.\n\nAbstractThe acoustic masking hypothesis states that auditory masking may occur if the target sound and interfering sounds overlap spectrally, and it suggests that animals exposed to noise will modify their acoustic signals to increase signal detectability. However, it is unclear if animals will put more effort into changing their signals that spectrally overlap more with the interfering sounds than when the signals overlap less. We examined the dynamic changes in the temporal features of echolocation and communication vocalizations of the Asian particolored bat (Vespertilio sinensis) when exposed to traffic noise. We hypothesized that traffic noise has a greater impact on communication vocalizations than on echolocation vocalizations and predicted that communication vocalization change would be greater than echolocation. The bats started to adjust echolocation vocalizations on the fourth day of noise exposure, including an increased number of call sequences, decreased number of calls, and vocal rate within a call sequence. However, there was little change in the duration of the call sequence. In contrast, these communication vocalization features were not significantly adjusted under noise conditions. These findings suggest that the degree of spectral overlap between noise and animal acoustic signals does not predict the level of temporal vocal response to the noise.

animal behavior and cognition↗

bioRxiv2018

Lag Effects in Primate Brain Size Evolution: A Re-Evaluation

The question as to whether there is a lag between brain and body mass evolution was ostensibly solved two decades ago by Deaner & Nunn (1999) who used phylogenetic methods to show that there was no evidence to suggest that changes in brain size lagged behind changes in body size. However, their assumption that body size would always change ahead of brain size is open to question. In addition, many of their datapoints are confounded by grade shift effects. A reanalysis of their data controlling for these confounds shows that there is in fact a strong lag effect, but that the direction of the lag is the reverse of that originally assumed: brain size typically changes first, and does so under selection from changes in group size. The data suggest that it takes about 2.0 million years for body size to converge back onto the conventional allometric relationship with brain size. In the meantime, species that have increased brain size are likely to incur a significant energy cost that must be met from elsewhere. I show that they seem to do so by changing to a more nutrient-rich diet.

animal behavior and cognition↗

bioRxiv2018

Acquiring absolute pitch in adulthood is difficult but possible

Absolute pitch (AP) refers to the rare ability to name the pitch of a tone without external reference. It is widely believed that AP is only for the selected few with rare genetic makeup and early musical training during the critical period. Accordingly, acquiring AP in adulthood is impossible. Previous studies have not offered a strong test of the effect of training because of issues like small sample size and insufficient training. In three experiments, adults learned to name pitches in a computerized and personalized protocol for 12 to 40 hours. They improved considerably, with a continuous distribution of learning progress among them. 14% of the participants (6 out of 43) were able to name twelve pitches at accuracy of 90% or above, comparable to that of AP possessors as defined in the literature. In general, AP learning showed classic characteristics of perceptual learning, including generalization of learning dependent on the training stimuli, and sustained improvement for at least one to three months. Overall, the finding that AP continues to be learnable in adulthood calls for reconsidering the role of learning in the occurrence of AP. The finding also pushes the field to pinpoint and explain, if any, the differences between the aspects of AP more trainable in adulthood and the aspects of AP that are potentially exclusive for the few exceptional AP possessors.

animal behavior and cognition↗

bioRxiv2018

The evolution of a beneficial association between an animal and a microbial community

Animals are now known to be intimately associated with microbial communities, some of which enhance animal fitness. Yet relatively little is known about how these beneficial associations initially arose. We investigated this problem with an experiment on burying beetles, Nicrophorus vespilloides, which breed on the body of a small dead vertebrate. We found that burying beetles breeding on germ-free mice produced smaller larvae, with lower fitness, than those breeding on conventional germ-laden mice. Thus, burying beetles gain benefits from the microbial community associated with their carrion breeding resource, because they lose fitness when this community is removed experimentally. Our experiment suggests that a symbiosis between an animal and a microbial community might begin as an adaptation to the microbial ecosystem in which the animal lives, even when these microbes exist outside the animal, are transiently associated with it at each generation and are not directly transmitted from parents to offspring.

animal behavior and cognition↗

bioRxiv2018

Mouse Models of GNAO1-Associated Movement Disorder: Allele- and sex-specific differences in phenotypes

Background\n\nInfants and children with dominant de novo mutations in GNAO1 exhibit movement disorders, epilepsy, or both. Children with loss-of-function (LOF) mutations exhibit Epileptiform Encephalopathy 17 (EIEE17). Gain-of-function (GOF) mutations or those with normal function are found in patients with Neurodevelopmental Disorder with Involuntary Movements (NEDIM). There is no animal model with a human mutant GNAO1 allele.\n\nObjectives\n\nHere we develop a mouse model carrying a human GNAO1 mutation and determine whether clinical features of the GNAO1 mutation including movement disorder would be evident in the mouse model.\n\nMethods\n\nA mouse Gnao1 knock-in GOF mutation (G203R) was created by CRISPR/Cas9 methods. The resulting offspring and littermate controls were subjected to a battery of behavioral tests. A previously reported GOF mutant mouse knock-in (Gnao1+/G184S) was also studied for comparison.\n\nResults\n\nGnao1+/G203R mutant mice are viable and gain weight comparably to controls. Homozygotes are non-viable. Grip strength was decreased in both males and females. Male Gnao1+/G203R mice were strongly affected in movement assays (RotaRod and DigiGait) while females were not. Male Gnao1+/G203R mice also showed enhanced seizure propensity in the pentylenetetrazole kindling test. Mice with a G184S GOF knock-in also showed movement-related behavioral phenotypes but females were more strongly affected than males.\n\nConclusions\n\nGnao1+/G203R mice phenocopy children with heterozygous GNAO1 G203R mutations, showing both movement disorder and a relatively mild epilepsy pattern. This mouse model should be useful in mechanistic and preclinical studies of GNAO1-related movement disorders.

animal behavior and cognition↗

bioRxiv2018

Computational modeling of social face perception in humans: Leveraging the active appearance model

Face processing plays a central role in human social life. Humans readily infer social traits (e.g. attractiveness and trustworthiness) from a strangers face. Previous attempts to characterize the facial (physiognomic) features underlying social processing have lacked either systematicity or interpretability. Here, we utilize a statistical framework to tackle this problem, by learning a vector space to represent faces, and a linear mapping from this face space into human social trait judgments. Specifically, we obtain a face space by training the Active Appearance Model on large datasets of face images. Based on human evaluations of numerous social traits on these images, we then use regression to find linear combinations of facial features (what we call Linear Trait Axis, or LTA) that best predict human social judgments. Our model achieves state-of-the-art performance in overall predictive accuracy - comparable to the best convolutional neural network and better than human prediction of other human ratings. To interpret the LTAs, we regress them against a large repertoire of geometric features. To understand the relationship between the facial features that underlie different social, emotional, and demographic traits, we present a novel \"dual space analysis\" that characterizes the geometric relationship among LTA vectors. It shows that facial features important for social trait perception are largely distinct from those underlying demographic and emotion perception, contrary to previous suggestions that social trait perception is driven by over-generalization of relatively primitive demographic and emotion perception processes. In addition, we present a novel correlation decomposition analysis that quantifies how correlations in trait judgments (e.g. between attractiveness and babyfacedness) independently arise from (1) shared facial features among traits, and (2) correlation in the distribution of facial features in the human population.

animal behavior and cognition↗

bioRxiv2018

Searching for structure in collective systems

Collective systems such as fish schools, bird flocks, and neural networks are comprised of many mutually-influencing individuals, often without long-term leaders, well-defined hierarchies, or persistent relationships. The remarkably organized group-level behaviors readily observable in these systems contrast with the ad hoc, often difficult to observe, and complex interactions among their constituents. While these complex individual-level dynamics are ultimately the drivers of group-level coordination, they do not necessarily offer the most parsimonious description of a groups macroscopic properties. Rather, the factors underlying group organization may be better described at some intermediate, mesoscopic scale. We introduce a novel method from information-theoretic first principles to find a compressed description of a system based on the actions and mutual dependencies of its constituents, thus revealing the natural structure of the collective. We emphasize that this method is computationally tractable and requires neither pairwise nor Gaussian assumptions about individual interactions.

animal behavior and cognition↗

bioRxiv2018

Excretion initiates walking in the cricket Gryllus bimaculatus

Feces contain information about the donor and potentially attracts both conspecifics and predators and parasites. The excretory system must be coordinated with other behaviors in insects. We found that crickets start walking forward following excretion of feces. Most intact crickets walked around the experimental arena, stopped at a particular site and raised up their body with a slight backward drift to excrete feces. After the feces dropped on the floor, the animal started walking with a random gait pattern away from the feces, and then changed the gait pattern to a tripod gait. Headless cricket also showed walking following excretion. In more than half of excretion events, headless crickets walked backward before excretion. The posture adopted during excretion was similar to that of intact crickets, and post-excretory forward walking was also observed. The occurrence rate of post-excretory walking was more than that of intact crickets. The gait pattern during forward walking was random and never transitioned to a tripod gait in the headless crickets. In animals whose abdominal nerve cords were cut, in any position, pre- or post-excretion walking was not shown in both intact and headless crickets, although they excreted feces. These results indicate that ascending signals from the terminal abdominal ganglion initiate leg movement through the neuronal circuits within thoracic ganglia, and that descending signals from the brain must regulate leg the motor circuit to express the appropriate walking gait.

animal behavior and cognition↗

bioRxiv2018

Moderate consistency in smooth newt behaviour

Behavioural consistency (i.e., personality) is a novel field of research in amphibians. Current published studies often address only one or two aspects of personality and therefore cannot assess more complex relationships and behavioural syndromes. This is the first study focusing on all relevant behavioural traits and their relationships in urodele amphibians. Based on the three trials of the experiment, we examined the consistency of activity (time spent moving), boldness (latency of the first movement and time spent escaping) and exploration (number of visited segments of testing arena) of 42 smooth newts (Lissotriton vulgaris). Individual consistency, calculated through the intraclass correlation coefficient (ICC), was low in newt activity (ICC = 0.192) and moderate in boldness (0.476) and exploration (0.403). Activity was moderately consistent for each trial (0.425), indicating a possible habituation, supported by a decrease of mean activity throughout the trials. Correlation of the behavioural traits studied suggests the presence of a behavioural syndrome, which potentially shaped the traits together. Our findings suggest the need for a complex approach to the study of amphibian personality and the need for standardized methodology, which would solve the current difficulties in comparing published results.

animal behavior and cognition↗

bioRxiv2018

Collective decision-making by rational individuals

The patterns and mechanisms of collective decision making in humans and animals have attracted both empirical and theoretical attention. Of particular interest has been the variety of social feedback rules, and the extent to which these behavioural rules can be explained and predicted from theories of rational estimation and decision making. However, models that aim to model the full range of social information use have incorporated ad hoc departures from rational decision-making theory to explain the apparent stochasticity and variability of behaviour. In this paper I develop a model of social information use and collective decision making by fully rational agents that reveals how a wide range of apparently stochastic social decision rules emerge from fundamental information asymmetries both between individuals, and between the decision-makers and the observer of those decisions. As well as showing that rational decision making is consistent with empirical observations of collective behaviour, this model makes several testable predictions about how individuals make decisions in groups, and offers a valuable perspective on how we view sources of variability in animal, and human, behaviour.

animal behavior and cognition↗

bioRxiv2018

Synchronised brood transport by ants occurs without communication

Collective behaviours in societies such as those formed by ants are thought to be the result of distributed mechanisms of information processing and direct decision-making by well-informed individuals, but their relative importance remains unclear. Here we tracked all ants and brood movements to investigate the decision strategy underlying brood transport in nests of the ant Camponotus fellah. Changes in environmental conditions induced workers to quickly transport the brood to a preferred location. Only a minority of the workers, mainly nurses, participated in this task. Using a large number of statistical tests we could further show that these transporters omitted to recruit help, and relied only on private information rather than information obtained from other workers. This reveals that synchronised group behaviour, often suggestive of coordinated actions among workers, can also occur in the complete absence of communication.

animal behavior and cognition↗

bioRxiv2018

Familiarity modulates social approach toward stressed conspecifics in female rats

Familiarity between conspecifics may influence how social affective cues shape social behaviors. In a social affective preference test, experimental rats, when given the choice to explore an unfamiliar stressed or a naive adult, will avoid interaction with a stressed conspecific. To determine if familiarity would influence social interactions with stressed conspecifics, male and female test rats underwent 2 social affective preference tests in isosexual triads where an experimental rat was presented with a naive and a stressed target conspecific who were either familiar (cagemate) or unfamiliar. Male and female experimental rats avoided stressed unfamiliar conspecifics. However, experimental female rats demonstrated a preference to interact with their stressed, familiar cagemates. Male and female rats exhibited more self-grooming and immobility behavior in the presence of stressed conspecifics, which may indicate emotion contagion. These findings suggest a sex-specific role of familiarity in social approach and avoidance, and warrant further mechanistic exploration.

animal behavior and cognition↗

bioRxiv2018

Intentional gestures predict complex sociality in wild chimpanzee

A key challenge for primates is coordinating behavior with conspecifics in large, complex social groups. Gestures play a key role in this process and chimpanzees show considerable flexibility communicating through single gestures, sequences of gestures interspersed with periods of response waiting (persistence) and rapid sequences where gestures are made in quick succession, too rapid for the response waiting to have occurred. Previous studies examined behavioral reactions to single gestures and sequences, but whether this complexity is associated with more complex sociality at the level of the dyad partner and the group as a whole is not well understood. We used social network analysis to examine how the production of single gestures and sequences of gestures was related to the duration of time spent in proximity and individual differences in proximity in wild East African chimpanzees (Pan troglodytes schweinfurthii). Pairs of chimpanzees that spent a longer duration of time in proximity had higher rates of persistence, but not a higher rate of single gesture or rapid sequences. Central individuals in the social network received higher rates of persistence, but not rapid sequence or single gesture. Intentional gestural communication plays an important role in regulating social interactions in complex primate societies.

animal behavior and cognition↗

bioRxiv2018

Memory Image Completion (MIC): Establishing a task to behaviorally assess pattern completion in humans

For memory retrieval, pattern completion is a crucial process that restores memories from partial or degraded cues. Neurocognitive aging models suggest that the aged memory system is biased toward pattern completion, resulting in a behavioral preference for retrieval over encoding of memories. While there are behavioral tasks to assess the encoding side of these memory differences, pattern completion has received less attention in the literature. Here, we built on our previously developed behavioral recognition memory paradigm - the Memory Image Completion task (MIC) - a task to specifically target pattern completion. First, we used the original design with concurrent eye-tracking in order to rule out perceptual confounds that could interact with recognition performance. Second, we developed parallel versions of the task to accommodate test settings in clinical environments or longitudinal studies. The results show that older adults have a deficit in pattern completion ability with a concurrent bias toward pattern completion - a replication of previously found effects. Importantly, eye-tracking data during encoding could not account for age-related performance differences. At retrieval, spatial viewing patterns for both age groups were more driven by stimulus identity than by response choice, but compared to young adults, older adults fixation patterns overlapped more between stimuli that they (wrongly) thought had the same identity. This supports the observation that when making errors older adults choose responses perceived as similar to the correct stimulus, which is interpreted as a bias toward pattern completion. Additionally, two shorter versions of the task yielded comparable results, and no general learning effects were observed for repeated testing. Together, we present evidence that the MIC is a reliable behavioral task that targets pattern completion, that is easily and repeatedly applicable, and that is made freely available online.

animal behavior and cognition↗

bioRxiv2018

Orienting to Polarized Light at Night-Matching Lunar Skylight to Performance in a Nocturnal Beetle

For polarized light to inform behaviour, the typical range of degrees of polarization observable in the animals natural environment must be above the threshold for detection and interpretation. Here we present the first investigation of the degree of linear polarization threshold for orientation behaviour in a nocturnal species, with specific reference to the range of degrees of polarization measured in the night sky. An effect of lunar phase on the degree of polarization of skylight was found, with smaller illuminated fractions of the moons surface corresponding to lower degrees of polarization in the night sky. We found that South African dung beetle Escarabaeus satyrus (Boheman, 1860) can orient to polarized light for a range of degrees of polarization similar to that observed in diurnal insects, reaching a lower threshold between 0.04 and 0.32, possibly as low as 0.11. For degrees of polarization lower than 0.23, as measured on a crescent moon night, orientation performance was considerably weaker than that observed for completely linearly-polarized stimuli, but was nonetheless stronger than in the absence of polarized light.\n\nSummary StatementA degree-of-polarization threshold for orientation behaviour is reported for nocturnal dung beetle Escarabaeus satyrus in the context of measurements showing changes in the degree of polarization of skylight with lunar phase.

animal behavior and cognition↗