Social learning in a maze? Contrasting individual performance among wild zebrafish when associated with trained and naïve conspecifics

The effect of observing trained conspecifics on the performance and motivation of goldfish, Carassius auratus, in a spatial task

Spatial and social cognition are two aspects of fish behaviour that have been subject to an increasing amount of research in recent years, but few have investigated potential behaviour overlaps. Testing the ability for an individual to socially learn a spatial task would bridge this gap in understanding. We provided naïve goldfish, Carassius auratus, the opportunity to observe a trained conspecific navigate a T-shaped maze, and then recorded how many trials it took for them to learn the maze, time taken per trial, motivation, and acceptance of the food reward. We also recorded how many trials it took a control group to learn the maze without the opportunity to observe a demonstrator. The observer group took significantly longer to learn the maze than the control group. Although the observer group were significantly less motivated (trials without a choice made), they were significantly more likely to accept the food reward. The social learning of reward acceptance was taking place, but the process of the demonstration disrupted the training of the spatial task, with possible explanations as the passenger effect and trade-off mechanism being discussed. Future studies are needed to determine whether goldfish can acquire spatial information socially; however, this study contributes to the feasibility of studying social learning of environmentally information in goldfish.

Correlations begin at home: drivers of co-occurrence patterns in personality and cognitive ability in wild populations of zebrafish

Aquatic habitats are extremely dynamic, with constantly changing ecological factors, which has now been exacerbated due to human-induced rapid environmental change. In such variable environments, it becomes essential to understand how personality and cognition in organisms affect the adaptability of individuals to different habitat conditions. To test this, we studied how personality-related traits as well as cognitive ability differ between populations of wild-caught zebrafish (Danio rerio) from habitats that differed in various environmental factors. We measured emergence into a novel environment as an indicator of boldness, and performance in a spatial task inferred from feeding latencies in a maze over repeated trials to assess learning and memory, as an indicator of cognitive ability. We found that personality affects cognition and although bolder fish are better learners, they show poorer retention of memory across populations. Although personality and cognitive ability varied between habitats, the patterns of their correlations remained similar within each population. However, the individual traits (such as sex and size) that were drivers of personality and cognition differed between the habitats, suggesting that not only do behavioral traits vary between populations, but also the factors that are important in determining them. Personality and cognitive ability and the correlations between these traits determine how well an organism performs in its habitat, as well as how likely it is to find new habitats and adapt to them. Studying these across wild zebrafish populations helps predict performance efficiencies among individuals and also explains how fish adapt to extremely dynamic environments that can lead to variation in behavioral traits and correlations between them. This study not only sheds light on the drivers of interindividual variation and co-occurrence patterns of personality and cognition, but also individual and population factors that might have an effect on them.

Consensus driven by a minority in heterogenous groups of the cockroach Periplaneta american a

Many social species are able to perform collective decisions and reach consensus. However, how the interplay between social interactions, the diversity of preferences among the group members and the group size affects these dynamics is usually overlooked. The collective choice between odourous and odorless shelters is tested for the following three groups of social cockroaches (Periplaneta americana) which are solitary foragers: naive (individuals preferring the odorous shelter), conditioned (individuals without preference), and mixed (combining, unevenly, conditioned, and naive individuals). The robustness of the consensus is not affected by the naive individuals' proportion, but the rate and the frequency of selection of the odorous shelter are correlated to this proportion. In mixed groups, the naive individuals act as influencers. Simulations based on the mechanisms highlighted in our experiments predict that the consensus emerges only for intermediate group sizes. The universality of these mechanisms suggests that such phenomena are widely present in social systems.

Swimming in the maze: An overview of maze apparatuses and protocols to assess zebrafish behavior

Most preclinical behavioral assays use rodents as model animals, leaving room for species-specific biases that could be avoided by an expanded cross-species approach. In this context, zebrafish emerges as an alternative model organism to study neurobiological mechanisms of anxiety, preference, learning, and memory, as well as other phenotypes with relevance to neuropsychiatric disorders. In recent years, several zebrafish studies using different types of mazes have been published. However, the protocols and apparatuses' shapes and dimensions vary widely in the literature. This variation may puzzle researchers attempting to implement maze behavioral assays and challenges the reproducibility across institutions. This review aims to provide an overview of the behavioral paradigms assessed in different types of mazes in zebrafish reported in the last couple of decades. Also, this review aims to contribute to a better characterization of multi-behavioral assessment in zebrafish.

Leveraging Social Learning to Enhance Captive Animal Care and Welfare

From ants to zebras, animals are influenced by the behavior of others. At the simplest level, social support can reduce neophobia, increasing animals’ exploration of novel spaces, foods, and other environmental stimuli. Animals can also learn new skills more quickly and more readily after observing others perform them. How then can we apply animals’ proclivity to socially learn to enhance their care and welfare in captive settings? Here, I review the ways in which animals (selectively) use social information, and propose tactics for leveraging that to refine the behavioral management of captive animals: to enhance socialization techniques, enrichment strategies, and training outcomes. It is also important to consider, however, that social learning does not always promote the uniform expression of new behaviors. There are differences in animals’ likelihood to seek out or use socially provided information, driven by characteristics such as species, rank, age, and personality. Additionally, social learning can result in inexact transmission or the transmission of undesirable behaviors. Thus, understanding when, how, and why animals use social information is key to developing effective strategies to improve how we care for animals across settings and, ultimately, enhance captive animal welfare.

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.

Teaching laboratory for large cohorts of undergraduates: Private and social information in fish

A challenge in the Bachelor's studies in Biology is to strike a balance between reducing the teaching of practical scientific experiments to what is feasible in a short time, and teaching "real" science in undergraduate laboratories for high numbers of participants. We describe a laboratory in behavioral biology, with the primary focus on the student learning. However, also the underlying scientific question and the results of the experiment, namely the behavior of the three-spined stickleback (Gasterosteus aculeatus) in a trade-off situation during foraging, is without a doubt timely and sufficient for scientific studies on this subject, and this through the experiments conducted and data collected by the students. The students rated this laboratory well and learned at the end that social information is certainly important, but that self-learning can be more important, and this not only in small fish, but also for the students themselves.

Color preferences affect learning in zebrafish, Danio rerio

Animals may exhibit preference for colors that match their environment or the resources in the environment. These preferences may impact ability to learn associations with these colors and revert the associations when the reward contingency is modified. We used zebrafish Danio rerio from four populations to test if color preferences impact associative and reversal learning ability. First, we tested if preference for blue or green impact associative ability. We subjected individual fish through eight trials to associate a social stimulus with blue or green. Next, we tested if preference for red or green impact associative reversal learning ability. We trained fish in groups of three to associate a social stimulus with red or green over three trials, and reversed the reward contingency during the following session. Results showed that zebrafish preferred green over blue and domesticated fish chose green more than blue when there was a reward attached. Zebrafish also preferred red over green. Fish from one wild population learned with both colors and reversed learning only from green to red and not vice-versa. Fish from another population showed an overwhelming preference for red irrespective of what was rewarded. Domesticated fish did not show reversal learning ability.

The zebrafish subcortical social brain as a model for studying social behavior disorders

Social behaviors are essential for the survival and reproduction of social species. Many, if not most, neuropsychiatric disorders in humans are either associated with underlying social deficits or are accompanied by social dysfunctions. Traditionally, rodent models have been used to model these behavioral impairments. However, rodent assays are often difficult to scale up and adapt to high-throughput formats, which severely limits their use for systems-level science. In recent years, an increasing number of studies have used zebrafish (Danio rerio) as a model system to study social behavior. These studies have demonstrated clear potential in overcoming some of the limitations of rodent models. In this Review, we explore the evolutionary conservation of a subcortical social brain between teleosts and mammals as the biological basis for using zebrafish to model human social behavior disorders, while summarizing relevant experimental tools and assays. We then discuss the recent advances gleaned from zebrafish social behavior assays, the applications of these assays to studying related disorders, and the opportunities and challenges that lie ahead.

Divergences in learning and memory among wild zebrafish: Do sex and body size play a role?

Given its diverse ecological distribution, zebrafish has great potential for investigations on the effect of habitat characteristics on cognition. Studies were conducted on four wild-caught zebrafish populations to understand the role of native habitat, sex, and body size in determining learning through a novel task associated with a food reward. The habitat variables, namely, the relative abundances of zebrafish and predatory fish and the substrate and vegetation diversity, were quantified during fish sampling. Fish were subjected to a novel task to find a food reward in a maze over successive training trials followed by a test for memory. Performances of subjects were based on time taken to find the food reward and number of mistakes made during trials, and tests for memory. The experiments revealed significant differences in learning rates and memory across populations. Males made significantly fewer mistakes than females only within two populations. No relationship between performance and body size was observed. The differences in learning and memory among wild zebrafish could be due to differences in predation, complexity, and stability of the native habitats. These findings suggest the possible role of multiple interacting factors in determining learning and memory among populations and point to a need for incorporating effects of several factors in future studies.

A method for rapid testing of social learning in vampire bats

Designing experiments on social learning using an untested behaviour or species requires baseline knowledge of how the animals will perform. We conducted a pilot study of a procedure for rapidly testing social learning in the highly social common vampire bat (Desmodus rotundus) using a simple maze. To create demonstrators, we allowed captive bats to learn to exit a three-dimensional maze, which reunited them with their colony as a reward. We then filmed naive bats in the same maze, comparing their ability to exit the maze before, during and after the addition of a trained demonstrator. The presence of a demonstrator increased the exit rates of naive bats, presumably by attracting the attention of the naive bats to the maze exit. Four of the five naive bats that exited in the presence of a demonstrator retained the ability to exit without the demonstrator. No naive bat exited during trials without a potential demonstrator present. This experimental procedure appears to be a promising approach for efficient tests of social learning in vampire bats because maze difficulty can be manipulated to adjust learning rates and each trial requires only 15 min.

Population, sex and body size: determinants of behavioural variations and behavioural correlations among wild zebrafish Danio rerio

This study (1) investigated variation among populations and the effects of sex and body size on boldness, activity and shoal-association tendency among wild zebrafish, and (2) tested for existence of correlations between behaviours, controlling for sex and body size. Individuals across four natural populations were tested for general activity in a novel situation, number of predator inspections undertaken and tendency to associate with a conspecific shoal in the presence of predators. Results showed a significant effect of population on boldness with a population from high-predation habitat being bolder than populations from low-predation habitats. Males showed significantly higher tendencies than females to associate with a conspecific shoal in the presence of predators. Further, a negative relationship was found between activity and boldness only within two low-predation populations. Individual body size had a strong effect on the activity-boldness relationship within the low-predation population from flowing water habitat. Smaller fish were bolder and less active while larger fish were more cautious and active. Overall, the results indicated that while population-level behavioural responses might be shaped by predation pressure, state-dependent factors could determine behavioural correlations among individuals within populations.