Behavioral Brain Research Research Articles

Sight of conspecific images induces changes in neurochemistry in zebrafish

Zebrafish are gaining popularity in behavioural brain research as this species combines practical simplicity with system complexity. The dopaminergic system has been thoroughly investigated using mammals. Dopamine plays important roles in motor function and reward. Zebrafish have dopamine receptors homologous to mammalian counterparts, and dopamine receptor antagonists as well as alcohol have been shown to exert significant effects on this species as measured using HPLC or behavioural methods. The sight of conspecifics was previously shown to be rewarding in zebrafish but whether this stimulus affects the dopaminergic system has not been studied. Here, we present animated images of zebrafish to the experimental zebrafish subject for varying lengths of time and quantify the amount of dopamine, DOPAC, serotonin and 5HIAA extracted from the subject's brain immediately after the stimulus presentation using HPLC with electrochemical detection. We find conspecific images to induce a robust behavioural response (attraction) in experimental zebrafish. Importantly, dopamine and DOPAC levels significantly increased in response to the presentation of conspecific images but not to scrambled images. Last, serotonin and 5HIAA levels did not significantly change in response to the conspecific images. We conclude that our findings, together with pervious studies, now conclusively demonstrate that the behavioural response induced by the appearance of conspecifics is mediated, at least partly, by the dopaminergic system in zebrafish.

Endogenous Noradrenaline and Fear Extinction Learning in Humans

Endogenous Noradrenaline and Fear Extinction Learning in Humans

The place escape/avoidance paradigm: A novel method to assess nociceptive processing

This paper summarizes a behavioral paradigm that was developed as a novel method to dissociate the multidimensional pain experience in rodents. The place escape/avoidance paradigm (PEAP) is based on the assumption that if animals escape and/or avoid a noxious stimulus, then the stimulus is aversive to the animal. Data is presented showing that when animals are placed in a specific environmental condition, they will perform purposeful behavior to escape and/or avoid the noxious stimulus. Additional data is presented to demonstrate the validity of the behavioral paradigm and how the paradigm has been used to test the hypothesis that the affective/motivational dimension of pain can be dissociated and studied independent of sensory pain processing. The behavioral paradigm highlights the emerging trend in the area of pain research and management towards developing more realistic behavioral paradigms to assess nociceptive processing in rodent models of chronic pain.

Automated visual choice discrimination learning in zebrafish (Danio rerio)

Training experimental animals to discriminate between different visual stimuli has been an important tool in cognitive neuroscience as well as in vision research for many decades. Current methods used for visual choice discrimination training of zebrafish require human observers for response tracking, stimulus presentation and reward delivery and, consequently, are very labor intensive and possibly experimenter biased. By combining video tracking of fish positions, stimulus presentation on computer monitors and food delivery by computer-controlled electromagnetic valves, we developed a method that allows for a fully automated training of multiple adult zebrafish to arbitrary visual stimuli in parallel. The standardized training procedure facilitates the comparison of results across different experiments and laboratories and contributes to the usability of zebrafish as vertebrate model organisms in behavioral brain research and vision research.

Impulsive rats are less maternal

Early life environment and maternal care can have long-lasting effects on behavior and physiology. Previously, we found that compared to mother-reared (MR) female rats, rats reared without mothers, siblings, and nest, through artificially rearing (AR), show reduced levels of maternal behavior when they grow up. These effects can be reversed if AR pups are provided with extra "licking-like" tactile stimulation during the preweaning period [Gonzalez et al. [2001] Developmental Psychobiology, 38(1), 11-42]. We also found that AR rats are more action impulsive and have reduced attentional capacities in comparison to their MR siblings [Lovic, Fletcher, & Fleming, in preparation; Lovic & Fleming [2004] Behavioural Brain Research 148: 209-219]. However, it is unknown whether increased impulsivity contributes to reduced levels of maternal behaviors. The purpose of this study was to assess the relationship between impulsivity and maternal behavior in AR and MR rats. Female rats were reared with (MR) or without mothers (AR) and half of the AR rats received additional stroking stimulation. As adults, AR and MR rats were mated and maternal behavior towards their own pups was assessed. In addition, rats were assessed on impulsive action (differential reinforcement of low-rate schedule; DRL-20s). Consistent with previous findings, AR rats were both less maternal and more action impulsive than MR rats. Partial correlations revealed that impulsivity was inversely related to pup licking-impulsive rats were less maternal.

Teaching & Learning Guide for: Once Upon a Time: Explaining Cultural Differences in Episodic Specificity

Teaching & Learning Guide for: Once Upon a Time: Explaining Cultural Differences in Episodic Specificity

MicroRNAs and Heart Failure Diagnosis

See related article, pages 1035–1039 Heart disease is the greatest noninfectious health hazard ever to confront the human race. It is the leading cause of death in industrialized nations, and, accordingly, it is responsible for a huge economic burden to society. It is estimated that 5 million Americans have heart failure (HF), a syndrome with mortality of approximately 50% at 5 years.1 Now, evidence indicates that the epidemic of HF is extending to the developing world. The road to advances in the treatment of HF is littered with failures, and many new means of diagnosing and tracking disease progression have disappointed. Therefore, there is an urgent need to identify novel mechanisms, markers, and therapeutic targets in HF pathogenesis. MicroRNAs (miRNAs or miRs) are among the most exciting areas in medicine and science today. MicroRNAs are endogenous, highly conserved, ≈22-nucleotide-long noncoding RNAs that regulate the stability and subsequent translation of nascent mRNA transcripts. Generally, miRs inhibit protein translation and/or promote mRNA degradation by base-pairing with 3′ untranslated regions within a transcript. MicroRNAs were first discovered in 1993 in Caenorhabditis elegans and are known to be critical to early vertebrate development and in an increasing number of basic molecular processes. Over the last few years, miRs have emerged as important mechanisms in human disease, including cardiovascular disease, diabetes, and cancer.2–6 Now, there is burgeoning interest in testing whether miRs could serve as markers for disease progression or prognostication. Indeed, in the cancer literature, strategies are emerging to use miR profiles for diagnosis and risk stratification. Currently, miR profiling is being evaluated in prostate cancer, head and neck squamous cell carcinomas, breast cancer, acute lymphoblastic leukemia, malignant mesothelioma, and other tumors.2,7–10 Most clinical studies to date on miRs have relied on tissue-based measurement of miR abundances, but miRs are …

Latent learning in zebrafish ( Danio rerio)

The zebrafish may represent an excellent compromise between system complexity and practical simplicity for behavioral brain research. It may be particularly appropriate for large scale screening studies whose aim is to identify mutants with altered phenotypes or novel compounds with particular efficacy. For example, the zebrafish may have utility in the analysis of the biological mechanisms of learning and memory. Although learning and memory have been extensively studied and hundreds of underlying molecular mechanisms have been identified, this number may represent only the fraction of genes involved in these complex brain functions. Thus large scale mutagenesis screens may have utility. In order for such screens to succeed, appropriate screening paradigms must be developed. The first step in this research is the characterization of learning and memory capabilities of zebrafish and the development of automatable tasks. Here we show that zebrafish is capable of latent learning, i.e. can acquire memory of their environment after being allowed to explore it. For example, we found experimental zebrafish that experienced an open left tunnel or an open right tunnel of a maze during the unrewarded exploration phase of the test to show the appropriate side bias during a probe trial when they had to swim to a group of conspecifics (the reward). Given that exploration of the maze does not require the presence of the experimenter and the probe trial, during which the subjects are video-recorded and their memory is tested, is short, we argue that the paradigm has utility in high-throughput screening.

Zebrafish ( Danio rerio) responds to the animated image of a predator: Towards the development of an automated aversive task

Zebrafish is gaining popularity in basic behavioral brain research, behavior genetics, and in translational studies because it offers a cheap and efficient alternative to rodents. Abnormally exaggerated fear and anxiety are some of the most prevalent neuropsychiatric diseases in the human society whose mechanisms are not well understood. These diseases still represent major unmet medical needs. Ethologically relevant fear paradigms involving the presentation of predators, or of stimuli characteristic of predators, have been proposed as appropriate for the modeling and the analysis of fear responses. Previously, we have shown that zebrafish respond specifically to visual stimuli of their sympatric predator, the Indian leaf fish. In the current paper we show that an animated (moving) image of this predator elicits significant behavioral responses and that these responses can be quantified using video-tracking. As stimulus presentation and behavioral response quantification are both computerized and automated, we suggest the paradigm is appropriate for high throughput screening and, once pharmacologically and behaviorally validated, may have utility in the detection of anxiolytic or anxiogenic properties of compounds or in the identification of fear altering mutations.

Shuttle box learning in zebrafish ( Danio rerio)

Zebrafish is used in forward genetic and drug screening and is gaining popularity in behavioral brain research but high throughput learning paradigms are lacking. The sight of conspecifics has been shown to be rewarding in zebrafish. Here, in a novel paradigm, subjects learn to respond to alternating presentation of computer-animated zebrafish images. The simplicity and computerization of the paradigm will make it useful for high throughput screening.

Differential role of the hippocampal endocannabinoid system in the memory consolidation and retrieval mechanisms

CB1 cannabinoid receptors are abundantly expressed in the brain, with large concentrations present in the hippocampus, a brain structure essential for memory processing. In the present study, we have investigated the possible modulatory role of the endocannabinoid system in the dorsal hippocampus upon the different phases of memory processing of an aversive task. AM251, a selective antagonist of CB1 receptors, and anandamide, an endogenous agonist of cannabinoid receptors, were bilaterally infused into the dorsal hippocampus of male Wistar rats either before training, immediately after training, or before test in the step-down inhibitory avoidance (IA) task. Results showed that pre-training infusion of CB1 drugs did not influence the acquisition of the task. In contrast, post-training infusion of the CB1 antagonist disrupted while the antagonist facilitated memory consolidation of IA. The post-training results demonstrate that memory consolidation depends on the integrity of the endocannabinoid system in the CA1 region of the dorsal hippocampus. While we still have no direct proof of endocannabinoids released there after an aversive task such as IA, these results suggests that (a) AM251 acts blocking the binding of endogenously released cannabinoids and (b) exogenously supplemented anandamide may be adding its contribution to the action of the endogenously released pool. Considering our data and the higher density of CB1 receptors present in the GABAergic interneurons, we propose them as the putative target of the endocannabinoid modulation of memory, a hypothesis that needs to be proven. In addition, pre-test infusion of the CB1 receptor antagonist facilitated while infusion of the agonist did not affect memory retrieval of IA. The completely opposite action of the same drug upon memory at the post-training (consolidation) and pre-test (recall) contexts suggests that some durable change took place in the CA1 region during the consolidation process that modified the logical attributes of the pharmacological response, i.e., the drug response changed from memory disruption to memory facilitation. A similar phenomenon was previously described by us in the M4 cholinergic muscarinic subsystem in the hippocampus for the same task (Diehl, F., Fürstenau, L. O., Sanchez, G., Camboim, C., de Oliveira Alvares, L., Lanziotti, V. B., et al. (2007). Facilitatory effect of the intra-hippocampal pretest administration of MT3 in the inhibitory avoidance task. Behavioral Brain Research, 177(2), 227–231), but the biological nature of such change in the local neural circuitry remains to be investigated.

Ketamine blocks the formation of a gustatory memory trace in rats

N-methyl- d-aspartate (NMDA) receptors appear to play a central role in learning and memory processes, as the administration of antagonistic substances of these receptors hinders learning acquisition by using different behavioral paradigms (e.g., Riedel G, Platt B, Micheau J. Glutamate receptor function in learning and memory. Behavioural Brain Research, 2003;140 (1–2):1–47.). In the specific case of conditioned taste aversion, the administration of ketamine seems to affect the acquisition of conditioning when the drugs are administered before the experimental treatment. In this paper we present three experiments designed to analyze the effect of different ketamine doses (25 mg/kg, 50 mg/kg, 75 mg/kg and 120 mg/kg), administered between exposure to a taste (the conditioned stimulus) and the administration of the unconditioned stimulus, on the acquisition of a taste aversion association. The results reveal that higher ketamine doses (75 mg/kg and 120 mg/kg) have a disruptive effect on conditioned taste aversion by impeding the formation of the gustatory trace.

Developmental aspects of automatic word processing: Language lateralization of early ERP components in children, young adults and middle-aged subjects

Reading words elicits a very early evoked potential termed “recognition potential” with a latency of about 150 ms and clearly located in left posterior regions. A review of the current literature indicates that N150 marks the automatic lexical classification of a word, is relatively independent of the task, and is followed by a later negative and more anterior component which is sensitive to the task. However, from the literature it is not clear whether the left lateralization of the neural networks involved in word recognition changes with age and experience, and how this lateralization is related with behavioral performance. To this aim, based on a previously validated paradigm [Spironelli, C., Angrilli, A., 2006. Language lateralization in Phonological, Semantic and Orthographic tasks: a slow evoked potential study. Behavioral Brain Research 175, 296–304; Spironelli, C., Angrilli, A., 2007. Influence of Phonological, Semantic and Orthographic tasks on the early linguistic components N150 and N350. International Journal of Psychophysiology 64, 190–198], we ran an experiment on three samples of subjects, 28 children (mean: 10 years), 22 young adults (23 years) and 20 middle-aged subjects (59 years). Subjects had to read the same sample of words in three blocked tasks, Orthographic, Phonological and Semantic, while EEG was recorded from 38 scalp locations. Analysis performed on N150 and four regions of interest/quadrants revealed typical significant left posterior negativity in young and aged subjects, but reversed lateralization and greater right negativity in children compared with the two adult groups. Analysis of the later N350 revealed a significant three-way group × laterality × task interaction, showing greater left negativity on the Phonological task only in the two adult groups, and a bilateral component in children. Results indicate that the functional lateralization of linguistic neural networks involved in automatic word recognition and in phonological processing is not yet developed in linguistically competent children aged 10 years, whereas the observed lateralization is relatively stable and not degraded in moderately aged subjects. Results are discussed in view of their implications for age-related linguistic pathologies.

Human Motor Behavior

Human Motor Behavior

Time stamp in conditioned place avoidance can be set to different circadian phases

We have reported that the expression of conditioned place avoidance (CPA) in the golden hamster is regulated in a circadian pattern such that the preference is exhibited strongly at the circadian time of prior training but not at other circadian times [Cain, S. W., Chou, T., & Ralph, M. R. (2004a). Circadian modulation of performance on an aversion-based place learning task in hamsters. Behavioural Brain Research, 150(1–2), 201–205]. In that study, animals that were trained at a specific circadian time to discriminate between a “safe” context and one paired with foot shock, showed strong avoidance of the paired context at 24 and 48 h following the last training session, and showed no avoidance at 32 and 40 h following training. In the present study, we hypothesized that this “time stamp” effect is settable to any circadian phase. This was tested by training animals at one of two times of day (ZT13 or ZT4) and testing whether a time stamp would be observed, with avoidance occurring only when training and testing times match. Results confirmed our hypothesis, suggesting that the time stamp in the performance of learned tasks can be set to any circadian phase. Such an ability may allow animals in nature to predict the recurrence of 24 h events, regardless of the time of day the event was encountered.

Control of the Corridor Illusion in Baboons (Papio Papio) by Gradient and Linear-Perspective Depth Cues

The corridor illusion was recently demonstrated in baboons with background pictures containing rich depth information (Barbet and Fagot 2002, Behavioural Brain Research 132 111-115). In the current research we determined the contribution of gradient texture and perspective lines to that illusion. In experiment 1, the corridor illusion was tested in two baboons, with pictures of a hallway as backgrounds, or the same image of the hallway represented by perspective lines. Findings confirmed that the baboons experience the corridor illusion with the picture of the hallway, and showed that this illusion remained with the perspective-line backgrounds. The same procedure was adopted in experiment 2, but with a hallway drawn from gradient textures. The two baboons experienced the illusion in this experiment too. Thus both gradient and perspective line cues convey sufficient information to control the corridor illusion in baboons. In baboons, the processing of these two kinds of depth cues interacts with the perception of object size, suggesting homologous processes of pictorial depth perception in humans and non-human primates.

Protecting the Brain With eNOS

See related article, pages 1132–1140 Nitric oxide (NO) plays a major role in both vascular and neural biology in health and disease. This concept is exemplified when one examines the role of NO in the brain and the cerebral circulation. NO is a potent vasodilator, and blood vessels in the brain are normally exposed to NO from 2 major sources—endothelium and neurons. Acting as a messenger molecule, NO mediates the majority of endothelium-dependent responses in the brain.1 The source of this NO is the endothelial isoform of NO synthase (eNOS). This prominent role for NO has been observed in a variety of blood vessels from multiple species including humans.1–3 Through this signaling mechanism, NO influences resting vascular tone and mediates responses to varied stimuli, including endothelium-dependent agonists and increases in blood flow (Figure).1,4,5 In addition, eNOS inhibits vasoconstrictor responses and cerebral vasospasm6–8 and can affect permeability of cerebral endothelium, the blood-brain barrier (Figure).9 eNOS normally inhibits cerebral vascular growth or hypertrophy (Figure),10 a structural change that can have functional consequences by impairing of maximal vasodilator capacity. Impairment of NO-mediated signaling is a key underlying mechanism of vascular dysfunction in diverse forms of disease and aging.1,11–13 Impairment of these eNOS-dependent mechanisms in the presence of cardiovascular risk factors may contribute to …

Face pictures reduce behavioural, autonomic, endocrine and neural indices of stress and fear in sheep.

Faces are highly emotive stimuli and we find smiling or familiar faces both attractive and comforting, even as young babies. Do other species with sophisticated face recognition skills, such as sheep, also respond to the emotional significance of familiar faces? We report that when sheep experience social isolation, the sight of familiar sheep face pictures compared with those of goats or inverted triangles significantly reduces behavioural (activity and protest vocalizations), autonomic (heart rate) and endocrine (cortisol and adrenaline) indices of stress. They also increase mRNA expression of activity-dependent genes (c-fos and zif/268) in brain regions specialized for processing faces (temporal and medial frontal cortices and basolateral amygdala) and for emotional control (orbitofrontal and cingulate cortex), and reduce their expression in regions associated with stress responses (hypothalamic paraventricular nucleus) and fear (central and lateral amygdala). Effects on face recognition, emotional control and fear centres are restricted to the right brain hemisphere. Results provide evidence that face pictures may be useful for relieving stress caused by unavoidable social isolation in sheep, and possibly other animal species, including humans. The finding that sheep, like humans, appear to have a right brain hemisphere involvement in the control of negative emotional experiences also suggests that functional lateralization of brain emotion systems may be a general feature in mammals.

Retrograde amnesia: neither partial nor complete hippocampal lesions in rats result in preferential sparing of remote spatial memory, even after reminding

Many lesion experiments have provided evidence that the hippocampus plays a time-limited role in memory, consistent with the operation of a systems-level memory consolidation process during which lasting neocortical memory traces become established [see Squire, L. R., Clark, R. E., & Knowlton, B. J. (2001). Retrograde amnesia. Hippocampus 11, 50]. However, large lesions of the hippocampus at different time intervals after acquisition of a watermaze spatial reference memory task have consistently resulted in temporally ungraded retrograde amnesia [Bolhuis, J. J., Stewart, C. A., Forrest, E. M. (1994). Retrograde amnesia and memory reactivation in rats with ibotenate lesions to the hippocampus or subiculum. Quarterly Journal of Experimental Psychology 47B, 129; Mumby, D. G., Astur, R. S., Weisend, M. P., Sutherland, R. J. (1999). Retrograde amnesia and selective damage to the hippocampal formation: memory for places and object discriminations. Behavioural Brain Research 106, 97; Sutherland, R. J., Weisend, M. P., Mumby, D., Astur, R. S., Hanlon, F. M., et al. (2001). Retrograde amnesia after hippocampal damage: recent vs. remote memories in two tasks. Hippocampus 11, 27]. It is possible that spatial memories acquired during such a task remain permanently dependent on the hippocampus, that chance performance may reflect a failure to access memory traces that are initially unexpressed but still present, or that graded retrograde amnesia for spatial information might only be observed following partial hippocampal lesions. This study examined the retrograde memory impairments of rats that received either partial or complete lesions of the hippocampus either 1–2 days, or 6 weeks after training in a watermaze reference memory task. Memory retention was assessed using a novel ‘reminding’ procedure consisting of a series of rewarded probe trials, allowing the measurement of both free recall and memory reactivation. Rats with complete hippocampal lesions exhibited stable, temporally ungraded retrograde amnesia, and could not be reminded of the correct location. Partially lesioned rats could be reminded of a recently learned platform location, but no recovery of remote memory was observed. These results offer no support for hippocampus-dependent consolidation of allocentric spatial information, and suggest that the hippocampus can play a long-lasting role in spatial memory. The nature of this role—in the storage, retrieval, or expression of memory—is discussed.

AAA award winners.

AAA award winners.