Active avoidance conditioning in zebrafish (Danio rerio)

The zebrafish represents a potentially useful organism for studying genes involved in learning and memory function in vertebrates, because a number of genetic techniques in zebrafish have been developed to produce a wide variety of genetic mutants. While zebrafish mutants are being developed, behavioral studies on learning and memory function in zebrafish are in urgent need. The present study investigated active avoidance conditioning in normal zebrafish. Zebrafish were trained to swim from a lighted (CS) compartment to a dark compartment to avoid an electrical body shock (US) in a shuttle-box that consisted of a water-filled tank separated by an opaque barrier into two equal compartments. By varying the number of trials per training session and the duration of the intertrial interval, Experiments 1 and 2 showed that, with the CS, US, and intertrial interval being 12s, zebrafish learned avoidance responses within a training session consisting of 30 trials and retained the avoidance responses. Experiment 3 showed that zebrafish learned avoidance responses following the association between the CS of light and the US of shock in the avoidance conditioning paradigm. Using the avoidance conditioning paradigm, Experiment 4 investigated the amnestic effects of N-methyl-D-aspartate receptor antagonist MK-801 and nitric oxide synthase inhibitor L-NAME in zebrafish. Experiment 4 showed that post-training injection of L-NAME significantly impaired retention of avoidance responses while MK-801 did not, confirming previous results with other vertebrates. The results of the present study suggest the similar involvements of neurochemicals in learning and memory among vertebrates. Thus, future studies with zebrafish mutants may identify genes involved in learning and memory in vertebrates.     

Spatial and non-spatial visual discrimination learning in zebrafish (Danio rerio)

Zebrafish (Danio rerio) provide an excellent model for assessment of molecular processes of neurodevelopment. To determine the functional importance of molecular events during neurodevelopment, we have developed methods for assessing learning in zebrafish in a three-chambered fish tank. In the first study, simple escape response was assessed. Zebrafish tested with a moving net learned to escape to another chamber more rapidly over the six sessions of training than the fish with the still net which did not learn. Upon reversal of the contingencies, the fish switched to the inactive net rapidly learned to suppress the escape response and fish formerly in the inactive net condition learned to avoid the moving net. In the second study, spatial discrimination learning was assessed. Zebrafish were trained on a right-left position discrimination to avoid the active net. Zebrafish showed significant improvement in escape responses over six sessions of training with three trials per session. In the third study, red-blue non-spatial discrimination learning was assessed. There was a significant improvement over the first six training sessions. With the reversal of contingencies, there was a significant decline of performance. With continued training, the fish again significantly improved avoidance. These studies found an effective motivational stimulus and procedure for studying escape behavior in zebrafish; a procedure whereby zebrafish would learn both spatial and non-spatial discrimination. These methods are being developed to help determine the functional importance of molecular events during zebrafish neurodevelopment. Accepted after revision: 20 August 2001 Electronic Publication     

Response acquisition by zebrafish (Danio rerio) with delayed reinforcement

Zebrafish (Danio rerio) is a common vertebrate animal model in biomedical research and is a promising species for studying how genes interact with environmental factors in determining behavior. The present study investigated how reinforcement parameters affect zebrafish behavior by assessing response acquisition with delayed reinforcement, which has been studied with other species (e.g., rats, pigeons, humans, etc.) but not with zebrafish. Twenty‐four experimentally naïve subjects were exposed to a tandem fixed‐ratio 1 differential‐reinforcement‐of‐other‐behavior x‐s schedule of reinforcement, where x varied across subjects. There were six different delay‐to‐reinforcement durations and sets of four fish were assigned to each delay duration. All of the fish assigned to a 0‐, 0.5‐, or 1‐s delay acquired responding. Two fish acquired responding with a 3‐s delay and one fish appeared to have acquired it with a 6‐s delay although the latter result was less clear. None acquired responding with a 12‐s delay. These results suggest that zebrafish behavior is sensitive to delays to reinforcement and the time frame over which reinforcement is effective may be limited approximately to 6 s. This time frame is shorter than that found with other species. Practical and theoretical implications of the present finding are discussed.     

Associative learning performance is impaired in zebrafish (Danio rerio) by the NMDA-R antagonist MK-801

The zebrafish is gaining popularity in behavioral neuroscience perhaps because of a promise of efficient large scale mutagenesis and drug screens that could identify a substantial number of yet undiscovered molecular players involved in complex traits. Learning and memory are complex functions of the brain and the analysis of their mechanisms may benefit from such large scale zebrafish screens. One bottleneck in this research is the paucity of appropriate behavioral screening paradigms, which may be due to the relatively uncharacterized nature of the behavior of this species. Here we show that zebrafish exhibit good learning performance in a task adapted from the mammalian literature, a plus maze in which zebrafish are required to associate a neutral visual stimulus with the presence of conspecifics, the rewarding unconditioned stimulus. Furthermore, we show that MK-801, a non-competitive NMDA-R antagonist, impairs memory performance in this maze when administered right after training or just before recall but not when given before training at a dose that does not impair motor function, perception or motivation. These results suggest that the plus maze associative learning paradigm has face and construct validity and that zebrafish may become an appropriate and translationally relevant study species for the analysis of the mechanisms of vertebrate, including mammalian, learning and memory.     

The ontogeny of continuous quantity discrimination in zebrafish larvae (Danio rerio)

Animal Cognition - Several studies have investigated the ontogeny of the capacity to discriminate between discrete numerical information in human and non-human animals. Contrarily, less attention...     

Predator videos and electric shock function as punishers for zebrafish (Danio rerio)

Zebrafish (Danio rerio) are a promising animal model for studying the effects of gene–environment interactions on behavior. Two experiments were conducted to assess punishment effects of presenting predator videos (Indian leaf fish; Nandus nandus) and electric shock on operant approach responses in zebrafish. In Experiment 1, the predator video and shock stimuli were presented upon a response maintained by a single variable‐interval schedule of food reinforcement in different groups of fish. In Experiment 2, the predator video and shock stimuli were presented upon one of two response alternatives maintain by concurrently available variable‐interval schedules of food reinforcement in different groups of fish. Responding decreased when the predator video and shock stimuli were presented relative to their absence in both experiments. Moreover, responding on an unpunished alternative did not reliably decrease in Experiment 2. These results indicate that the decrease in responding resulted from the punishment contingency rather than from elicited species‐specific defense responses or conditioned avoidance. Thus, the predator video and electric shock functioned as punishers of operant behavior for zebrafish. Identifying punishers for this species could lead to research on how gene–environment interactions influence individual differences in sensitivity to punishment.     

Insensitivity to reward shifts in zebrafish (Danio rerio) and implications for assessing affective states

Animal Cognition - Theory and empirical findings predict that individuals in a negative affective state are more sensitive to unexpected reward loss and less sensitive to unexpected reward gain...     

Subcutaneous dye injection for marking and identification of individual adult zebrafish (Danio rerio) in behavioral studies

The zebrafish is increasingly utilized in behavioral brain research, as it offers a useful compromise between system complexity and practical simplicity. However, a potential drawback of this species in behavioral research is that individuals are difficult to distinguish. Here we describe a simple marking procedure, subcutaneous injection of color dyes, that may alleviate this problem. The procedure allowed us to successfully mark zebrafish and distinguish them for a period of more than 30 days, which is sufficiently long for most behavioral paradigms developed for this species. In addition, we also provide data suggesting that the injection-based marking does not significantly alter social interaction, as defined by the frequency of agonistic behaviors within shoals.     

Redundancy in task assignments and group performance

The problem of combining abilities of group members to maximize the performance of the group as a whole is examined in terms of redundancy in task assignments. In particular, ways of distributing a given number of items of information among a given number of individuals to obtain the maximum probability of each item being recalled by at least one individual are studied. It is shown that there exists an optimal distribution scheme which is independent of the amount of material originally given, the size of the group, and individual differences in ability.This work was done under the sponsorship of the Behavioral Sciences Division, Air Force Office of Scientific Research, Contract AF 49(630)-33.     

Sex differences in social buffering and social contagion of alarm responses in zebrafish

Animal Cognition - The alarm substance in fish is a pheromone released by injured individuals after a predator attack. When detected by other fish, it triggers fear/defensive responses, such as...     

Bullying as a group process: Participant roles and their relations to social status within the group

Bullying was investigated as a group process, a social phenomenon taking place in a school setting among 573 Finnish sixth-grade children (286 girls, 287 boys) aged 12–13 years. Different Participant Roles taken by individual children in the bullying process were examined and related to a) self-estimated behavior in bullying situations, b) social acceptance and social rejection, and c) belongingness to one of the five sociometric status groups (popular, rejected, neglected, controversial, and average). The Participant Roles assigned to the subject were Victim, Bully, Reinforcer of the bully, Assistant of the bully, Defender of the victim, and Outsider. There were significant sex differences in the distribution of Participant Roles. Boys were more frequently in the roles of Bully, Reinforcer and Assistant, while the most frequent roles of the girls were those of Defender and Outsider. The subjects were moderately well aware of their Participant Roles, although they underestimated their participation in active bullying behavior and emphasized that they acted as Defenders and Outsiders. The sociometric status of the children was found to be connected to their Participant Roles. © 1996 Wiley-Liss, Inc.     

Sleep deprivation effects on object discrimination task in zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

The zebrafish is an ideal vertebrate model for neurobehavioral studies with translational relevance to humans. Many aspects of sleep have been studied, but we still do not understand how and why sleep deprivation alters behavioral and physiological processes. A number of hypotheses suggest its role in memory consolidation. In this respect, the aim of this study was to analyze the effects of sleep deprivation on memory in zebrafish (Danio rerio), using an object discrimination paradigm. Four treatments were tested: control, partial sleep deprivation, total sleep deprivation by light pulses, and total sleep deprivation by extended light. The control group explored the new object more than the known object, indicating clear discrimination. The partially sleep-deprived group explored the new object more than the other object in the discrimination phase, suggesting a certain degree of discriminative performance. By contrast, both total sleep deprivation groups equally explored all objects, regardless of their novelty. It seems that only one night of sleep deprivation is enough to affect discriminative response in zebrafish, indicating its negative impact on cognitive processes. We suggest that this study could be a useful screening tool for cognitive dysfunction and a better understanding of the effect of sleep-wake cycles on cognition.     

Age differences in the effects of social influence on children's eyewitness performance and their metacognitive monitoring

The current work investigated the effects of social influence on children's recall accuracy and metacognitive monitoring. Two studies were conducted in which 8- and 10-year-olds were confronted with postevent information in an interview situation. An interviewer (Study 1) or a confederate (Study 2) provided postevent information with two levels of assertiveness, inducing (a) a variation of conformity pressure and (b) a variation of information credibility. Afterwards, children's confidence judgments were assessed. The results revealed significant age differences in children's ability to adequately cope with variations of social influence. Although conformity pressure was especially important for the 8-year-olds, effects of informative social influence were independent of age. However, 10-year-olds were also able to act appropriately on low credibility, thereby demonstrating a more sophisticated consideration of social influence sources. Moreover, varying assertiveness also affected the quality of children's confidence judgments by improving their metacognitive differentiation skills.     

Sex differences in performance on a combined manual and decision task.

This report describes results of an experimental study of the differences in response time between 10 male and 10 female undergraduate operators performing a combined manual and decision task. Analysis indicated that the performance times of women on such tasks were shorter than those of the men as expected.     

Help yourself by helping others: The joint impact of group member organizational citizenship behaviors and group cohesiveness on group member objective task performance change

This paper examines how a group member's individual‐targeted citizenship behavior (OCBI) and organization‐targeted citizenship behavior (OCBO) interact with a salient group‐level contextual variable, group cohesiveness, to foster positive change for that group member, starting with job self‐efficacy change, and followed by objective task performance change. Over a span of 6 months, we engaged in multilevel, multisource, multistage data collection and surveyed 587 members in 83 work groups. Our results indicate that a group member's OCBI, in comparison with OCBO, is more positively related to his or her job self‐efficacy change. Group cohesiveness was found to attenuate the relationship between a group member's OCBI and job self‐efficacy change, and conversely, to accentuate the relationship between a group member's OCBO and job self‐efficacy change. Furthermore, a group member's job self‐efficacy change mediated the interactive effects of the group member's OCBI and group cohesiveness (as well as the group member's OCBO and group cohesiveness) on his or her objective task performance change.     

Social roles and social perception: individual differences in attribution and error

In a replication of the social roles experiment by Ross, Amabile, and Steinmetz (1977), 103 male and female 14-year-olds viewed a brief videotape that showed a randomly assigned "questioner" asking general knowledge questions of a "contestant," who answered most of them incorrectly. Subjects subsequently manifested the role-based attribution error of attributing significantly more knowledge and ability to the arbitrarily designated questioner than to the arbitrarily designated contestant, and this effect was stronger among girls than boys. Personality data were available on the subjects for when they were in nursery school and again at age 14 in the form of independent Q-sort ratings. Personality correlates of the role effect were stronger among boys but manifested a basically similar pattern among girls and suggested that those most prone to make this attribution error, far from being disadvantaged in social judgment, tended to be more socially engaged and competent as well as emotionally well adjusted. The role effect was also positively associated with self-esteem. Personality correlates of attributional generosity and the tendency to attribute high ability to stimulus persons were associated with generally positive interpersonal qualities and attitudes. Results were interpreted in terms of usually appropriate heuristic social competencies that, in special circumstances, may sometimes underlie attribution errors. The general usefulness of examining individual differences in research on social cognition was noted.     

The effects of sex differences and evaluation on task performance and aspiration

An investigation was conducted of how evaluation differentially affects the performance and aspiration for future performance of 118 high school boys and girls. Subjects were selected to fit into either a superior or average intelligence group. In the high evaluation condition, subjects were instructed that their intelligence was being evaluated in anagram and visual-motor tasks they performed, while those in the low evaluation condition were instructed that the two tasks were being correlated. It was hypothesized that on a highly evaluated task, girls, when compared to boys, would show greater performance debilitation and would have lower aspirations for future performance. Although sex differences were found in performance debilitation and aspiration for future performance, they were not all in the predicted directions. Girls were equally debilitated in anagram performance under both evaluation conditions, while boys were debilitated in anagram performance only under high evaluation. When both boys and girls demonstrated a performance debilitation on the anagram task, their performance declined approximately 10%. No sex differences in performance were found on the visual-motor task. On both tasks, girls' aspirations were significantly affected by evaluation condition. The girls averaged 89% choosing the more difficult task in the low evaluation condition. Evaluation condition had no significant effect on aspiration for boys on either task. Intelligence showed no significant relationships.