ETHOWATCHER: validation of a tool for behavioral and video-tracking analysis in laboratory animals

A Review of Freely Available, Open-Source Software for the Automated Analysis of the Behavior of Adult Zebrafish

The analysis of behavior in animal models is an important objective in many research fields, including neuroscience, psychology, toxicology, and neuropsychopharmacology. Animal models have been used for many years, and several behavioral paradigms, such as locomotor activity, social interactions, and cognitive behavior, have been studied in animal models to correlate the behaviors with pharmacological or environmental interventions and with molecular, biochemical, and physiological findings. We reviewed the literature looking for open-source, freely available software to analyze animal behavior and found 12 freely available programs: ToxTrack, EthoWatcher, Mouse Behavior Tracker, Mouse Move, JAABA, wrMTrck, AnimalTracker, idTracker, Ctrax, Mousetracker, VideoHacking, and Cowlog, which were developed with different programs, work on different platforms, and have particular types of inputs and outputs and analysis capabilities. We reviewed some examples of their use, tested some of them, and provided several recommendations for the future development of programs for the automated analysis of behavior in animal models. In conclusion, we show freely available software for the automated analysis of behavior in animal models such as adult zebrafish and provide information for researchers and students looking for quick, easy-to-implement, and inexpensive behavior analysis alternatives.

MouBeAT: A New and Open Toolbox for Guided Analysis of Behavioral Tests in Mice

Animal behavioral tests are essential to understand the bases of neurologic and psychological disorders, which can be evaluated by different methodological and experimental models. However, the quantification of behavioral tests results is limited by the considerable amount of time needed for manual evaluation and the high costs of automated analysis software. To overcome these limitations, we describe here a new, open source toolbox for ImageJ, called Mouse Behavioral Analysis Toolbox (MouBeAT), designed to analyze different behavioral tests in rodents semi-automatically. These tests include Open Field (OF), Elevated Plus Maze (EPM), Y-maze (YM) test and Morris Water Maze (MWM). MouBeAT showed a high correlation with manual evaluation in all the parameters analyzed for all the behavioral tests, reinforcing its value as an accurate analysis tool. This new tool is freely available online.

The McGill Transgenic Rat Model of Alzheimer's Disease Displays Cognitive and Motor Impairments, Changes in Anxiety and Social Behavior, and Altered Circadian Activity

The McGill-R-Thy1-APP transgenic rat is an animal model of the familial form of Alzheimer's disease (AD). This model mirrors several neuropathological hallmarks of the disease, including the accumulation of beta-amyloid and the formation of amyloid plaques (in homozygous animals only), neuroinflammation and the gradual deterioration of cognitive functions even prior to plaque formation, although it lacks the tauopathy observed in human victims of AD. The goal of the present study was a thorough characterization of the homozygous model with emphasis on its face validity in several domains of behavior known to be affected in AD patients, including cognitive functions, motor coordination, emotionality, sociability, and circadian activity patterns. On the behavioral level, we found normal locomotor activity in spontaneous exploration, but problems with balance and gait coordination, increased anxiety and severely impaired spatial cognition in 4–7 month old homozygous animals. The profile of social behavior and ultrasonic communication was altered in the McGill rats, without a general social withdrawal. McGill rats also exhibited changes in circadian profile, with a shorter free-running period and increased total activity during the subjective night, without signs of sleep disturbances during the inactive phase. Expression of circadian clock gene Bmal1 was found to be increased in the parietal cortex and cerebellum, while Nr1d1 expression was not changed. The clock-controlled gene Prok2 expression was found to be elevated in the parietal cortex and hippocampus, which might have contributed to the observed changes in circadian phenotype. We conclude that the phenotype in the McGill rat model is not restricted to the cognitive domain, but also includes gait problems, changes in emotionality, social behavior, and circadian profiles. Our findings show that the model should be useful for the development of new therapeutic approaches targeting not only memory decline but also other symptoms decreasing the quality of life of AD patients.

UMATracker: an intuitive image-based tracking platform

Image-based tracking software are regarded as valuable tools in collective animal behaviour studies. For such operations, image preprocessing is a prerequisite, and the users are required to build an appropriate image-processing pipeline for extracting the shape of animals. Even if the users successfully design an image-processing pipeline, unexpected noise in the video frame may significantly reduce the tracking accuracy in the tracking step. To address these issues, we propose UMATracker (Useful Multiple Animal Tracker), which supports flexible image preprocessing by visual programming, multiple tracking algorithms and a manual tracking error-correction system. UMATracker employs a visual programming user interface, wherein the user can intuitively design an image-processing pipeline. Moreover, the software also enables the user to visualize the effect of image processing. We implement four different tracking algorithms to enable the users to choose the most suitable algorithm. In addition, UMATracker provides a manual correction tool for identifying and correcting tracking errors.

Stearidonic acid combined with alpha-linolenic acid improves lipemic and neurological markers in a rat model subject to a hypercaloric diet

In this study, we hypothesized that terrestrial plant oils, rich in alpha linolenic acid (ALA) and stearidonic acid (SDA) relative to fish oil, rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), prevent negative effects on cardiovascular and neurological function using a rat model fed a hypercaloric diet. Results showed effects on the FA profile, namely, eicosapentaenoic, EPA, and docosahexaenoic, DHA, levels. There were also effects on neural aspects (cAMP response element-binding protein, CREB, gene expression, at least, doubled) and the pro-inflammatory/anti-inflammatory balance (TNF-α, tumor necrosis factor alpha reduced by 30-50%). The most positive impact of ALA and SDA was the beneficial reduction of total lipids (from 395 ± 3 to 352-361 mg/dL), VLDL-cholesterol (from 21.8 ± 0.2 to 14.1-17.8 mg/dL), and triacylglycerols (from 109 ± 1 to 71-89 mg/dL) in both LIN (diet enriched in linseed oil) and BUG (diet enriched in Buglossoides oil) groups. Overall, data indicate that ALA- and SDA-rich lipid sources may counteract the undesirable cardiovascular effects of a hypercaloric diet based on milk fat.

Failure to detect the action of antidepressants in the forced swim test in Swiss mice

OBJECTIVE

The aims of this study were to replicate previously published experiments and to modify the protocol to detect the effects of chronic antidepressant treatment in mice.

METHODS

Male Swiss mice (n=6-8/group) housed in reversed light/dark cycle were randomly assigned into receive vehicle (10% sucrose), sub-effective doses (1 and 3 mg/kg) or effective doses (10 and 30 mg/kg) of bupropion, desipramine, and fluoxetine and a candidate antidepressant, sodium butyrate (1-30 mg/kg) per gavage (p.o.) 1 h before the forced swim test (FST). Treatments continued daily for 7 and 14 days during retests 1 and 2, respectively. In an additional experiment, mice received fluoxetine (20 mg/kg) or vehicle (10% sucrose or 0.9% saline) p.o. or i.p. before the FST. Mice housed in reversed or standard light/dark cycles received fluoxetine (20 mg/kg) prior FST. Video recordings of behavioural testing were used for blind assessment of the outcomes.

RESULTS

According to the expected, doses of antidepressants considered sub-effective failed to affect the immobility time of mice in the FST. Surprisingly, acute and chronic treatment with the high doses of bupropion, desipramine, and fluoxetine or sodium butyrate also failed to reduce the immobility time of mice in the FST. Fluoxetine 20 mg/kg was also ineffective in the FST when injected i.p. or in mice housed in normal light/dark cycle.

CONCLUSION

Data suggest the lack of efficacy of orally administered bupropion, desipramine, fluoxetine in the FST in Swiss mice. High variability, due to high and low immobility mice, may explain the limited effects of the treatments.

Neonatal immune activation by lipopolysaccharide causes inadequate emotional responses to novel situations but no changes in anxiety or cognitive behavior in Wistar rats

Infection during the prenatal or neonatal stages of life is considered one of the major risk factors for the development of mental diseases such as schizophrenia or autism. However, the impacts of such an immune challenge on adult behavior are still not clear. In our study, we used a model of early postnatal immune activation by the application of bacterial endotoxin lipopolysaccharide (LPS) to rat pups at a dose of 2 mg/kg from postnatal day (PD) 5 to PD 9. In adulthood, the rats were tested in a battery of tasks probing various aspects of behavior: spontaneous activity (open field test), social behavior (social interactions and female bedding exploration), anxiety (elevated plus maze), cognition (active place avoidance in Carousel) and emotional response (ultrasonic vocalization recording). Moreover, we tested sensitivity to acute challenge with MK-801, a psychotomimetic drug. Our results show that the application of LPS led to increased self-grooming in the female bedding exploration test and inadequate emotional reactions in Carousel maze displayed by ultrasonic vocalizations. However, it did not have serious consequences on exploration, locomotion, social behavior or cognition. Furthermore, exposition to MK-801 did not trigger social or cognitive deficits in the LPS-treated rats. We conclude that the emotional domain is the most sensitive to the changes induced by neonatal immune activation in rats, including a disrupted response to novel and stressful situations in early adulthood (similar to that observed in human patients suffering from schizophrenia or autism), while other aspects of tested behavior remain unaffected.

A noninterfering system to measure in-cage spontaneous physical activity in mice

Due to lack of low-cost and convenient measurement procedures, uncontrolled changes in spontaneous physical activity (SPA) level often are insufficiently considered as a confounding factor in rodent studies. Nonetheless, alterations in SPA can significantly impact on a wide range of physiological measurements. Therefore, we developed an accurate, low-cost video tracking procedure to allow routine assessment of SPA in the home cage of experimental animals (i.e., mice) and in the absence of any distress that might cause alterations in SPA. SPA parameters acquired (movement distance, movement time, and movement speed) with the novel tracking system were identical to those simultaneously obtained with a high-end and well-validated movement-tracking device (mean error = 0.15 ± 0.07%, r = 0.99, P < 0.001). To further validate the setup, we also demonstrated caffeine-induced stimulation of SPA (195% more activity compared with vehicle, P < 0.01), we adequately reproduced typical SPA fluctuations inherent to day/night cycles (146 and 702% more active during nocturnal compared with diurnal cycle for Balb/c and C57BL/6J mice, respectively, P < 0.001), and we confirmed previously documented SPA differences between animal strains (24% less activity in C57BL/6J mice compared with Balb/c mice, P < 0.05). Taken together, we provide data to prove that this novel low-cost methodology can be conveniently used in any mouse experiment where uncontrolled changes in SPA due to experimental interventions might confound data interpretation. By analogy, the system can be used to document a beneficial impact of therapeutic interventions on SPA in any disease mouse model. NEW & NOTEWORTHY We developed a low-cost procedure to routinely measure SPA in mice. The procedure maintains normal SPA because the animals continue to stay in their home cage in the absence of any external manipulation by the investigators and under habitual dark/light ambient conditions. This novel methodology can be conveniently used in any mouse experiment to quantify experimentally induced alterations in SPA or to assess natural variations in SPA that might confound data interpretation.

Repeated forced-swimming test in intact female rats: behaviour, oestrous cycle and enriched environment

Psychopharmacology used animal models to study the effects of drugs on brain and behaviour. The repeated forced-swimming test (rFST), which is used to assess the gradual effects of antidepressants on rat behaviour, was standardized only in males. Because of the known sex differences in rats, experimental conditions standardized for males may not apply to female rats. Therefore, the present work aimed to standardize experimental and housing conditions for the rFST in female rats. Young or adult Wistar female rats were housed in standard or enriched environments for different experimental periods. As assessed in tested and nontested females, all rats had reached sexual maturity by the time behavioural testing occurred. The rFST consisted of a 15-min session of forced swimming (pretest), followed by 5-min sessions at 1 (test), 7 (retest 1) and 14 days (retest 2) later. The oestrous cycle was registered immediately before every behavioural session. All sessions were videotaped for further analysis. The immobility time of female rats remained similar over the different sessions of rFST independent of the age, the phase of the oestrous cycle or the housing conditions. These data indicate that rFST in female Wistar rats may be reproducible in different experimental conditions.

Non-target impacts of soybean insecticidal seed treatments on the life history and behavior of Podisus nigrispinus, a predator of fall armyworm

The treatment of seeds with systemic insecticides has become a common practice worldwide. However, this prophylactic use of insecticides has been questioned recently because of the potential risks to non-target organisms. This study assessed the non-target effects of chlorantraniliprole and thiamethoxam seed treatments on the life history and walking behavior of Podisus nigrispinus (Dallas), as well as the efficacy of these insecticides for controlling Spodoptera frugiperda (Smith). Thiamethoxam caused mortality of P. nigrispinus, increased the pre-oviposition period, and reduced the oviposition period and the fecundity and survival of females compared to chlorantraniliprole. In contrast, the life expectancy of P. nigrispinus females was prolonged by chlorantraniliprole, which also increased the intrinsic rate of growth (rm) and the finite growth rate (λ), and reduced the population doubling time (DT) compared to thiamethoxam. The net reproductive rate (R0) and mean generation time (T) were not affected by either insecticide treatment, and neither were the walking velocity of P. nigrispinus females, nor the distance they covered. Both chlorantraniliprole and thiamethoxam reduced soybean leaf consumption by S. frugiperda larvae. Given the observed lethal and sublethal effects, soybean seed treatments with chlorantraniliprole and thiamethoxam were judged to present low and moderate risks for P. nigrispinus, respectively.

Protective effect of aspirin treatment on mouse behavior in the acute phase of experimental infection with Trypanosoma cruzi

Chagas disease is a potentially fatal disease caused by the parasite Trypanosoma cruzi, which can in some cases affect the central nervous system. The objective was to evaluate the effect of aspirin (ASA) in the behavior of mice infected with T. cruzi during the acute phase. This was an experimental study with random assignation. Twenty four BALB/c mice were divided into four groups of six animals each as follows: only ASA (OA), ASA before infection (BI), ASA after infection (AI) and only infection (OI). The strain used for infection was M/HOM/Bra/53/Y. An ASA dose of 100 mg/kg per day was administered 72 h before infection to BI group and the same dose 48 h after infection to AI group. Mice behavior in the open field test, mortality, and brain histopathology was evaluated. Data were analyzed using ANOVA, chi square test, and Kaplan-Meier with long-rank for survival analysis. In the open field test, the OA group has similar results with the BI group, in the variables of immobility and escape. Also, the OA group displayed significantly higher rates of micturition (p < 0.001) and defecation (p < 0.001) compared to infected groups. Mortality was higher in BI group (p = 0.02). The presence of T. cruzi amastigotes were higher in brain tissues of the AI and OI groups (p = 0.008). In conclusion, the administration of ASA before infection seemed to prevent behavioral changes induced by the acute infection, but it led to accelerated mortality. The study highlighted the potential importance of the pathways inhibited by ASA in the early hours of acute infection with T. cruzi.

Mouse Behavior Tracker: An economical method for tracking behavior in home cages

Analysis of mouse behavior often requires expensive equipment and transfer of the mice to new test environments, which could trigger confounding behavior alterations. Here, we describe a system for tracking mouse behavior in home cages using a low-cost USB webcam and free software (Fiji and wrMTrck). We demonstrate the effectiveness of this method by tracking differences in distance traveled, speed, and movement tracks between wild-type mice and amyotrophic lateral sclerosis (ALS) model mice (SOD1G93A).

Markers of neuroprotection of combined EPA and DHA provided by fish oil are higher than those of EPA (Nannochloropsis) and DHA (Schizochytrium) from microalgae oils in Wistar rats

Background

To overcome the current overexploitation of fish rich in n-3 long chain polyunsaturated fatty acids (LCPUFA), microalgae have become a promising marine lipid source. The purpose of this study was to assess eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), isolated or combined from distinct marine origins, on the promotion of neuroprotective effects.

Methods

The experiment lasted for 10 weeks and involved 32 Wistar rats, divided into 4 diets (n = 8): a diet rich in milk fat was taken as control (Milk Fat) and compared to n-3 LCPUFA enriched diets, either in EPA + DHA form through fish oil (Fish Oil), or EPA through Nannochloropsis oil (Nanno), or DHA through Schizochytrium oil (Schyzo), while maintaining Milk Fat incorporation.

Results

Plasma lipid profile and dopamine levels were more beneficial in Fish Oil diet. In addition, n-3 LCPUFA incorporation was found increased in liver and erythrocytes from Fish Oil fed rats, suggesting that fish oil is a better dietary source for fatty acids deposition in the organism than microalgae. The Forced Swimming Test revealed a positive behavioural action of EPA + DHA, in opposition to Milk Fat and Nanno diets, which had higher immobile times. mRNA levels of serotonin receptors, HT1A and HT2A along with CREB, the transmission factor for learning and memory, were higher in the hippocampus of rats fed n-3 LCPUFA diets comparative to Milk Fat.

Conclusion

Taken together, the combination of EPA and DHA from fish oil can counteract the undesirable health effects of saturated fat based diets and benefit, in the long run, neurological function.

CA1 inactivation impairs episodic-like memory in rats

Episodic memory was initially believed to be unique to humans. However, studies demonstrate that nonhuman species discriminate items based on the triad what, where and when. Here we addressed the role of the dorsal hippocampal subfield CA1 in an integrative what-where-when task in Wistar rats. We performed bilateral inactivation of dorsal CA1 with the GABA_A agonist muscimol previously to the task. As expected, sham-operated animals recollected an integrative memory for objects (what), their places (where) and temporal order (when). However, the inactivation of CA1 impaired the performance of the three components of episodic-like memory. In addition, total time of objects exploration and distance traveled were not different between groups, indicating that rats had similar levels of motivation, thus, alterations in exploration does not account for impaired locomotor performance. Altogether, our data provides evidence that CA1 plays an important role in episodic-like memory.

Kinoscope: An Open-Source Computer Program for Behavioral Pharmacologists

Behavioral analysis in preclinical neuropsychopharmacology relies on the accurate measurement of animal behavior. Several excellent solutions for computer-assisted behavioral analysis are available for specialized behavioral laboratories wishing to invest significant resources. Herein, we present an open source straightforward software solution aiming at the rapid and easy introduction to an experimental workflow, and at the improvement of training staff members in a better and more reproducible manual scoring of behavioral experiments with the use of visual aids-maps. Currently the program readily supports the Forced Swim Test, Novel Object Recognition test and the Elevated Plus maze test, but with minor modifications can be used for scoring virtually any behavioral test. Additional modules, with predefined templates and scoring parameters, are continuously added. Importantly, the prominent use of visual maps has been shown to improve, in a student-engaging manner, the training and auditing of scoring in behavioral rodent experiments.

A novel automated rodent tracker (ART), demonstrated in a mouse model of amyotrophic lateral sclerosis

BACKGROUND

Generating quantitative metrics of rodent locomotion and general behaviours from video footage is important in behavioural neuroscience studies. However, there is not yet a free software system that can process large amounts of video data with minimal user interventions.

NEW METHOD

Here we propose a new, automated rodent tracker (ART) that uses a simple rule-based system to quickly and robustly track rodent nose and body points, with minimal user input. Tracked points can then be used to identify behaviours, approximate body size and provide locomotion metrics, such as speed and distance.

RESULTS

ART was demonstrated here on video recordings of a SOD1 mouse model, of amyotrophic lateral sclerosis, aged 30, 60, 90 and 120days. Results showed a robust decline in locomotion speeds, as well as a reduction in object exploration and forward movement, with an increase in the time spent still. Body size approximations (centroid width), showed a significant decrease from P30.

COMPARISON WITH EXISTING METHOD(S)

ART performed to a very similar accuracy as manual tracking and Ethovision (a commercially available alternative), with average differences in coordinate points of 0.6 and 0.8mm, respectively. However, it required much less user intervention than Ethovision (6 as opposed to 30 mouse clicks) and worked robustly over more videos.

CONCLUSIONS

ART provides an open-source option for behavioural analysis of rodents, performing to the same standards as commercially available software. It can be considered a validated, and accessible, alternative for researchers for whom non-invasive quantification of natural rodent behaviour is desirable.

A low-cost system to easily measure spontaneous physical activity in rodents

Spontaneous physical activity (SPA) can be responsible for variations of a lot of physiological parameters at the molecular, cellular, tissue, and systemic levels. It is increasingly recognized that good understanding of a large part of experimental results requires weighting them by SPA in order to reduce variability and thus to decrease the number of animals necessary to conduct a study. However, because of the high cost of this equipment, only a few laboratories are equipped with such equipment to measure the SPA of their animals. Here we present an effective, adaptable, and affordable system to measure SPA in rodents based on video acquisition of the animal in its own environment. We compared results obtained with our system to those collected at the same time with a commercial system of actimetry recording, and we found a high degree of correlation between these two approaches ( r = 0.93; P < 0.001). We also were able to detect small variations of SPA induced by a special environment like chronic hypoxia exposure (25% less spontaneous activity compared with animals in normoxia, P < 0.05) or during the circadian cycle (107% more activity during the nocturnal phase compared with the diurnal phase, P < 0.05).

Aplysia Locomotion: Network and Behavioral Actions of GdFFD, a D-Amino Acid-Containing Neuropeptide

One emerging principle is that neuromodulators, such as neuropeptides, regulate multiple behaviors, particularly motivated behaviors, e.g., feeding and locomotion. However, how neuromodulators act on multiple neural networks to exert their actions remains poorly understood. These actions depend on the chemical form of the peptide, e.g., an alternation of L- to D- form of an amino acid can endow the peptide with bioactivity, as is the case for the Aplysia peptide GdFFD (where dF indicates D-phenylalanine). GdFFD has been shown to act as an extrinsic neuromodulator in the feeding network, while the all L-amino acid form, GFFD, was not bioactive. Given that both GdFFD/GFFD are also present in pedal neurons that mediate locomotion, we sought to determine whether they impact locomotion. We first examined effects of both peptides on isolated ganglia, and monitored fictive programs using the parapedal commissural nerve (PPCN). Indeed, GdFFD was bioactive and GFFD was not. GdFFD increased the frequency with which neural activity was observed in the PPCN. In part, there was an increase in bursting spiking activity that resembled fictive locomotion. Additionally, there was significant activity between bursts. To determine how the peptide-induced activity in the isolated CNS is translated into behavior, we recorded animal movements, and developed a computer program to automatically track the animal and calculate the path of movement and velocity of locomotion. We found that GdFFD significantly reduced locomotion and induced a foot curl. These data suggest that the increase in PPCN activity observed in the isolated CNS during GdFFD application corresponds to a reduction, rather than an increase, in locomotion. In contrast, GFFD had no effect. Thus, our study suggests that GdFFD may act as an intrinsic neuromodulator in the Aplysia locomotor network. More generally, our study indicates that physiological and behavioral analyses should be combined to evaluate peptide actions.

MouseMove: an open source program for semi-automated analysis of movement and cognitive testing in rodents

The Open Field (OF) test is one of the most commonly used assays for assessing exploratory behaviour and generalised locomotor activity in rodents. Nevertheless, the vast majority of researchers still rely upon costly commercial systems for recording and analysing OF test results. Consequently, our aim was to design a freely available program for analysing the OF test and to provide an accompanying protocol that was minimally invasive, rapid, unbiased, without the need for specialised equipment or training. Similar to commercial systems, we show that our software—called MouseMove—accurately quantifies numerous parameters of movement including travel distance, speed, turning and curvature. To assess its utility, we used MouseMove to quantify unilateral locomotor deficits in mice following the filament-induced middle cerebral artery occlusion model of acute ischemic stroke. MouseMove can also monitor movement within defined regions-of-interest and is therefore suitable for analysing the Novel Object Recognition test and other field-related cognitive tests. To the best of our knowledge, MouseMove is the first open source software capable of providing qualitative and quantitative information on mouse locomotion in a semi-automated and high-throughput fashion, and hence MouseMove represents a sound alternative to commercial movement analysis systems.

Predation risk modulates diet-induced obesity in male C57BL/6 mice

OBJECTIVE

In this study, the behavioral and physiological changes induced by experimentally varying the risk of predation in male mice fed a high-fat diet were examined. In particular, the study aimed to assess whether the risk of being predated modulates the body weight gain, providing an ecological context for the obesity resistance observed in many species of small mammals.

METHODS

Body weight, food intake, physical activity, and core body temperature of 35 male C57BL/6 mice were monitored for 20 days, while feeding a high-fat diet. A third of the animals were exposed to elevated risk of predation through exposure to the sounds of nocturnal predatory birds, and these were compared to animals exposed to a neutral noise or silence.

RESULTS

Male mice exposed to predation risk had significantly lower weight gain than the neutral or silent groups. Reduced food intake and increased physical activity were the main proximal factors explaining this effect. The risk of predation also induced changes in boldness.

CONCLUSIONS

This study provides evidence supporting the role of predation risk on body weight gain of small mammals.

Consistent individual differences in haemolymph density reflect risk propensity in a marine invertebrate

While the literature on consistent individual differences in correlated suites of physiological and behavioural traits is steadily growing for vertebrates, invertebrates have received less attention. The few studies that do exist have measured temporary physiological states (or responses), rather than consistent individual physiological traits. Here, I explore the consistency of individual differences in physiology and behaviour of n=53 shore crabs (Carcinus maenas) by repeatedly measuring haemolymph density (HD) and the crabs' responses to a novel environment. In crustaceans, HD is directly proportional to protein concentrations, and thus indicative of physiological condition. HD was highly repeatable, and crabs showed consistent individual differences in their behavioural responses to a novel environment, thus indicating individual consistency in both physiology and behaviour. Furthermore, HD was significantly correlated with the crabs' risk propensity, i.e. individuals with higher HD spent more time near shelter. Overall, this provides the first evidence for consistency in an endogenous physiological trait in an invertebrate. The link between consistent physiology and behaviour, i.e. coping styles, analogous to those found in vertebrates, suggests metabolic and/or immunological correlates of personality which offer great potential for future studies.

An animal model of female adolescent cannabinoid exposure elicits a long-lasting deficit in presynaptic long-term plasticity

Cannabis continues to be the most accessible and popular illicit recreational drug. Whereas current data link adolescence cannabinoid exposure to increased risk for dependence on other drugs, depression, anxiety disorders and psychosis, the mechanism(s) underlying these adverse effects remains controversial. Here we show in a mouse model of female adolescent cannabinoid exposure deficient endocannabinoid (eCB)-mediated signaling and presynaptic forms of long-term depression at adult central glutamatergic synapses in the prefrontal cortex. Increasing endocannabinoid levels by blockade of monoacylglycerol lipase, the primary enzyme responsible for degrading the endocannabinoid 2-arachidonoylglycerol (2-AG), with the specific inhibitor JZL 184 ameliorates eCB-LTD deficits. The observed deficit in cortical presynaptic signaling may represent a neural maladaptation underlying network instability and abnormal cognitive functioning. Our study suggests that adolescent cannabinoid exposure may permanently impair brain functions, including the brain's intrinsic ability to appropriately adapt to external influences.

Distribution of serotonin 5-HT1A-binding sites in the brainstem and the hypothalamus, and their roles in 5-HT-induced sleep and ingestive behaviors in rock pigeons (Columba livia)

Serotonin 1A receptors (5-HT1ARs), which are widely distributed in the mammalian brain, participate in cognitive and emotional functions. In birds, 5-HT1ARs are expressed in prosencephalic areas involved in visual and cognitive functions. Diverse evidence supports 5-HT1AR-mediated 5-HT-induced ingestive and sleep behaviors in birds. Here, we describe the distribution of 5-HT1ARs in the hypothalamus and brainstem of birds, analyze their potential roles in sleep and ingestive behaviors, and attempt to determine the involvement of auto-/hetero-5-HT1ARs in these behaviors. In 6 pigeons, the anatomical distribution of [(3)H]8-OH-DPAT binding in the rostral brainstem and hypothalamus was examined. Ingestive/sleep behaviors were recorded (1h) in 16 pigeons pretreated with MM77 (a heterosynaptic 5-HT1AR antagonist; 23 or 69 nmol) for 20 min, followed by intracerebroventricular ICV injection of 5-HT (N:8; 150 nmol), 8-OH-DPAT (DPAT, a 5-HT1A,7R agonist, 30 nmol N:8) or vehicle. 5-HT- and DPAT-induced sleep and ingestive behaviors, brainstem 5-HT neuronal density and brain 5-HT content were examined in 12 pigeons, pretreated by ICV with the 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) or vehicle (N:6/group). The distribution of brainstem and diencephalic c-Fos immunoreactivity after ICV injection of 5-HT, DPAT or vehicle (N:5/group) into birds provided with or denied access to water is also described. 5-HT1ARs are concentrated in the brainstem 5-HTergic areas and throughout the periventricular hypothalamus, preoptic nuclei and circumventricular organs. 5-HT and DPAT produced a complex c-Fos expression pattern in the 5-HT1AR-enriched preoptic hypothalamus and the circumventricular organs, which are related to drinking and sleep regulation, but modestly affected c-Fos expression in 5-HTergic neurons. The 5-HT-induced ingestivebehaviors and the 5-HT- and DPAT-induced sleep behaviors were reduced by MM77 pretreatment. 5,7-DHT increased sleep per se, decreased tryptophan hydroxylase expression in the raphe nuclei and decreased prosencephalic 5-HT release but failed to affect 5-HT- or DPAT-induced drinking or sleep behavior. 5-HT- and DPAT-induced ingestive and sleep behaviors in pigeons appear to be mediated by heterosynaptic and/or non-somatodendritic presynaptic 5-HT1ARs localized to periventricular diencephalic circuits.

Influence of enrichment on behavioral and neurogenic effects of antidepressants in Wistar rats submitted to repeated forced swim test

Repeated forced swimming test (rFST) may detect gradual effects of antidepressants in adult rats. Antidepressants, as enrichment, affected behavior and neurogenesis in rats. However, the influence of enrichment on behavioral and neurogenic effects of antidepressants is unknown. Here, effects of antidepressants on rFST and hippocampal neurogenesis were investigated in rats under enriched conditions. Behaviors of male Wistar rats, housed from weaning in standard (SE) or enriched environment (EE), were registered during rFST. The rFST consisted of 15min of swimming (pretest) followed by 5min of swimming in the first (test), seventh (retest 1) and fourteenth (retest 2) days after pretest. One hour before the test, rats received an intraperitoneal injection of saline (1ml/kg), fluoxetine (2.5mg/kg) or imipramine (2.5 or 5mg/kg). These treatments were performed daily until the day of the retest 2. After retest 2, rats were euthanized for the identification of markers for neurogenesis in the hippocampus. Fluoxetine or imipramine decreased immobility in retests 1 and 2, as compared to saline. EE abolished these differences. In EE, fluoxetine or imipramine (5mg/kg) reduced immobility time in retest 2, as compared to the test. Independent of the housing conditions, fluoxetine and imipramine (5mg/kg) increased the ratio of immature neurons per progenitor cell in the hippocampus. In summary, antidepressants or enrichment counteracted the high immobility in rFST. Enrichment changed the effects of antidepressants in rFST depending on the type, and the dose of a substance but failed to change neurogenesis in control or antidepressant treated-rats. Effects of antidepressants and enrichment on rFST seemed neurogenesis-independent.

Statins enhance cognitive performance in object location test in albino Swiss mice: involvement of beta-adrenoceptors

Statins are inhibitors of the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, thereby inhibiting cell synthesis of cholesterol and isoprenoids. Moreover, several studies have been evaluating pleiotropic effects of statins, mainly because they present neuroprotective effects in various pathological conditions. However, knowledge about behavioral effects of statins per se is relatively scarce. Considering these facts, we aimed to analyze behavioral responses of atorvastatin or simvastatin-treated mice in the open field test, elevated plus maze and object location test. Atorvastatin treatment for 7 consecutive days at 1 mg/kg or 10 mg/kg (v.o.) or simvastatin 10 mg/kg or 20 mg/kg enhanced cognitive performance in object location test when compared to control group (saline-treated mice). Simvastatin effects on mice performance in the object location test was abolished by post-training infusion of the beta-adrenoceptor antagonist propranolol. Atorvastatin and simvastatin did not change the behavioral response in open field and elevated plus-maze (EPM) tests in any of the used doses. These data demonstrate the positive effects of both statins in cognitive processes in mice, without any alteration in locomotor parameters in the open field test or anxiolytic-like behavior in EPM. In conclusion, we demonstrate that atorvastatin and simvastatin per se improve the cognitive performance in a rodent model of spatial memory and this effect is related to beta-adrenergic receptors modulation.

Visualizing and quantifying movement from pre-recorded videos: The spectral time-lapse (STL) algorithm

When studying animal behaviour within an open environment, movement-related data are often important for behavioural analyses. Therefore, simple and efficient techniques are needed to present and analyze the data of such movements. However, it is challenging to present both spatial and temporal information of movements within a two-dimensional image representation. To address this challenge, we developed the spectral time-lapse (STL) algorithm that re-codes an animal’s position at every time point with a time-specific color, and overlays it with a reference frame of the video, to produce a summary image. We additionally incorporated automated motion tracking, such that the animal’s position can be extracted and summary statistics such as path length and duration can be calculated, as well as instantaneous velocity and acceleration. Here we describe the STL algorithm and offer a freely available MATLAB toolbox that implements the algorithm and allows for a large degree of end-user control and flexibility.