Facing uncertainties: The longitudinal relationship between childhood maltreatment and exploratory behavior

BACKGROUND

Exploratory behavior, as an essential component of decision-making, is indispensable for maximizing long-term benefits, making it a crucial factor in adolescents' psychological well-being and social adaptation. Despite the established understanding that this adaptive behavior is shaped by early adverse experiences, limited knowledge exists regarding the longitudinal relationship between childhood maltreatment and exploratory behavior.

OBJECTIVE

The present study examines whether childhood maltreatment would impede subsequent exploratory behavior, considering the mediating role of uncertainty stress and the moderating role of intolerance of uncertainty.

PARTICIPANTS AND SETTING

Participants were 655 adolescents from a longitudinal design with two waves spanning six months (Mage = 15.99, SDage = 0.92, 43.5 % female).

METHODS

Correlation analysis and longitudinal moderated mediation effect testing were used to test our hypotheses.

RESULTS

Correlation analysis indicated that childhood maltreatment was negatively correlated with exploratory behavior only simultaneously but not longitudinally. After controlling age and gender, childhood maltreatment would accompany higher levels of uncertainty stress, which in turn may act as a driving force behind subsequent exploratory behavior. The heightened intolerance of uncertainty may potentially mitigate the direct link between childhood maltreatment and later exploratory behavior. Furthermore, this trait amplifies the experienced uncertainty stress in individuals who have undergone maltreatment, thereby increasing their inclination toward engaging in subsequent exploratory behavior.

CONCLUSIONS

Given the critical role of uncertainty stress, promoting more exploration among these maltreated adolescents requires corresponding cognitive and behavioral interventions to adjust their perception and cognition of uncertainty.

Specific inhibitor of Wnt/beta-catenin pathway can alter behavioral responses in young rats with malformed cortices

The Wnt/beta-catenin pathway plays a crucial role in regulating cellular processes and has been implicated in neural activity-dependent learning as well as anxiety. However, the role of this pathway in young children with abnormal cortical development is unknown. Cortical malformations at early development, behavioral abnormalities, and a susceptibility to seizures have been reported in rats prenatally exposed to methylazoxymethanol. In this study, we aimed to investigate whether we could improve the behavioral deficits in young rats with malformed cerebral cortices by modulation of the Wnt/beta-catenin pathway. We found a small molecule Wnt/beta-catenin inhibitor (CWP) that increased exploratory behavior in the open field test (P9, CWP 100 ug treatment, peripheral exploration, P = 0.011) and social behavior test (P12, CWP 250 ug treatment, distance traveled in center, P = 0.033) and decreased anxiety in fear conditioning. However, it did not reduce the susceptibility to seizures. After high dose (250 ug) CWP treatment at P12, phosphocreatine and glutathione (GSH) were decreased in the cortex at P15 (P = 0.021). These findings suggest that the role of Wnt/beta-catenin signaling in exploratory behavior and anxiety during early development warrants further investigation.

Continuous high-frequency repetitive transcranial magnetic stimulation at extremely low intensity affects exploratory behavior and spatial cognition in mice

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has been shown to be effective for cognitive intervention. However, whether HF-rTMS with extremely low intensity could influence cognitive functions is still under investigation. The present study systematically investigated the effects of continuous 40 Hz and 10 Hz rTMS on cognition in young adult mice at extremely low intensity (10 mT and 1 mT) for 11 days (30 min/day). Cognitive functions were assessed using diverse behavioral tasks, including the open field, Y-maze, and Barnes maze paradigms. We found that 40 Hz rTMS significantly impaired exploratory behavior and spatial memory in both 10 mT and 1 mT conditions. In addition, 40 Hz rTMS induced remarkably different effects on exploratory behavior between 10 mT and 1mT, compared to 10 Hz stimulation. Our results indicate that extremely low intensity rTMS can significantly alter cognitive performance depending on intensity and frequency, shedding light on the understanding of the mechanism of rTMS effects.

Environmental levels of azoxystrobin disturb male zebrafish behavior: Possible roles of oxidative stress, cholinergic system, and dopaminergic system

A widely applied pesticide of azoxystrobin, is increasingly detected in the water environment. Concern has been raised against its potential detriment to aquatic ecosystems. It has been shown that exposure to azoxystrobin interfere with the locomotor behavior of zebrafish larvae. This study aims to investigate whether exposure to environmental levels of azoxystrobin (2 μg/L, 20 μg/L, and 200 μg/L) changes the behavior of male adult zebrafish. Herein, we evaluated behavioral response (locomotor, anxiety-like, and exploratory behaviors), histopathology, biochemical indicators, and gene expression in male adult zebrafish upon azoxystrobin exposure. The study showed that exposure to azoxystrobin for 42 days remarkably increased the locomotor ability of male zebrafish, resulted in anxiety-like behavior, and inhibited exploratory behavior. After treatment with 200 μg/L azoxystrobin, vasodilatation, and congestion were observed in male zebrafish brains. Exposure to 200 μg/L azoxystrobin notably elevated ROS level, MDA concentration, CAT activity, and AChE activity, while inhibiting SOD activity, GPx activity, ACh concentration, and DA concentration in male zebrafish brains. Moreover, the expression levels of genes related to the antioxidant, cholinergic, and dopaminergic systems were significantly changed. This suggests that azoxystrobin may interfere with the homeostasis of neurotransmitters by causing oxidative stress in male zebrafish brains, thus affecting the behavioral response of male zebrafish.

A psychiatric drug found in waste-water plant effluents alters the migratory behavior of critically endangered Anguilla anguilla juveniles

Migratory fishes cross or settle in several environments potentially polluted. Psychiatric drugs, which represent one growing pollution and are found in discharges from waste-water treatment plants, may alter individual behaviors. Here, we assessed behavioral alterations in the upstream migratory behavior of Anguilla anguilla caused by diazepam, an anxiolytic. We monitored the swimming activity, swimming behavior, and boldness to assess whether diazepam impacts them or not. Our 7-day behavioral follow-up allowed us to test the kinetics of the potential effects of diazepam. We found diazepam reduced swimming activity and altered individual swimming behavior, with fewer individuals swimming against the current, so swimming upstream. Those effects varied over time and were stronger at the end of our monitoring, suggesting chemical pollutants encountered in estuaries may act as a chemical burden for individuals, despite metabolisation. We also found diazepam favored bolder behavior in glass eels. Our results provide new knowledge on chemical pollution and psychiatric drugs inducing behavioral alterations. Those alterations may have ecological and evolutionary consequences for glass eels, by diminishing predator avoidance and impacting spatial colonization, and thus, local density.

A sewing needle as a urethral foreign body: A case report and literature review

Foreign bodies in the urethra can occur by self-insertion, and patients often hide the symptoms due to embarrassment. Foreign bodies act as a focus for infection and abscess formation and result in perforation or fistula when not detected on time. Foreign bodies can display symptoms such as frequent urination, dysuria, hematuria, urethrorrhagia, and obstruction. This case discusses a self-inserted urethral sewing needle that was removed cystoscopically from an adolescent.

Calcified clumped neodymium magnetic spheres as an intravesical foreign body: case report and literature review

Foreign bodies in the bladder can occur by self-insertion, and patients often hide the symptoms owing to embarrassment. The foreign bodies act as a nidus for calculus formation when not detected for a long time. Foreign bodies can declare symptoms such as frequency, dysuria, nocturia, hematuria, urethrorrhagia, obstruction, or retention. This case spotlights self-inserted intravesical neodymium magnetic spheres clumped and calcified due to delayed presentation which were removed by open cystotomy after a cystoscopic failure.

Atomoxetine promotes incentive value of modafinil and sensitizes exploratory behavior

Substance dependence is a disorder that alters the functioning of the nervous system due to frequent abuse of drugs. The role of dopamine in the addictive effect of psychostimulants is well known; however, the involvement of the noradrenergic system is still unclear and poorly understood, though drugs like cocaine and amphetamines are known to exert significant activity on this system. The drug modafinil (MOD) has no proven addictive effect. It promotes wakefulness by acting mainly on the dopaminergic system and, to a lesser degree, the noradrenergic (NOR) system. Atomoxetine (ATX) is a non-stimulant drug that acts only on the NOR system, enhancing its activity. The aims of the present study were to analyze the effect of co-activating the DA and NOR systems (with MOD and ATX, respectively) on motor activity and exploratory behavior, and to examine the possible emergence of rewarding properties of MOD and an MOD+ATX mixture. Male Wistar rats at postnatal day 60 were treated chronically (16 days) with either monotherapy with 2ATX, 4ATX, or 60MOD mg/kg, two combinations of these substances -60MOD + 2ATX and 60MOD + 4ATX- or a vehicle. The rats co-administered with 60MOD + 4ATX reduced the rearing behavior frequency induced by MOD, but this behavior was sensitized by self-administration of the MOD+ATX mixture after chronic treatment. The rats pre-treated with 60MOD + 4ATX showed higher self-administration of MOD and greater activity on an operant task to obtain the MOD+ATX mixture. In addition, the 60MOD, 2ATX, and 60MOD + 2ATX groups showed sensitization of exploratory behavior after ingesting the mixture. Results suggest that the noradrenergic system enhances the incentive value of MOD and a MOD+ATX mixture, while also playing an important role in the sensitization of exploratory behavior.

Alpha-synuclein pre-formed fibrils injected into prefrontal cortex primarily spread to cortical and subcortical structures and lead to isolated behavioral symptoms

Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are characterized by diffuse spread of alpha-synuclein (α-syn) throughout the brain. Patients with PDD and DLB have a neuropsychological pattern of deficits that include executive dysfunction, such as abnormalities in planning, timing, working memory, and behavioral flexibility. The prefrontal cortex (PFC) plays a major role in normal executive function and often develops α-syn aggregates in DLB and PDD. To investigate the consequences of α-syn pathology in the cortex, we injected human α-syn pre-formed fibrils into the PFC of wildtype mice. We report that PFC PFFs: 1) induced α-syn aggregation in multiple cortical and subcortical regions with sparse aggregation in midbrain and brainstem nuclei; 2) did not affect interval timing or spatial learning acquisition but did mildly alter behavioral flexibility as measured by intraday reversal learning; 3) increased open field exploration; and 4) did not affect susceptibility to an inflammatory challenge. This model of cortical-dominant pathology aids in our understanding of how local α-syn aggregation might impact some symptoms in PDD and DLB.

Acute intranasal oxytocin dose enhances social preference for parents over peers in male but not female peri-adolescent California mice (Peromyscus californicus)

Peri-adolescence is a critical developmental stage marked by profound changes in the valence of social interactions with parents and peers. We hypothesized that the oxytocin (OXT) and vasopressin (AVP) systems, known for influencing social behavior, would be involved in the maintenance and breaking of bonding behavior expressed by very early peri-adolescent males and females. In rodents, OXT is associated with mother-pup bonding and may promote social attachment to members of the natal territory. AVP, on the other hand, can act in contrasting ways to OXT and has been associated with aggression and territoriality. Specifically, we predicted that in peri-adolescent male and female juveniles of the biparental and territorial California mouse (Peromyscus californicus), a) OXT would increase the social preferences for the parents over unfamiliar age-matched peers (one male and one female), and b) AVP would break the parent-offspring bond and either increase time in the neutral chamber and/or approach to their unfamiliar and novel peers. We examined anxiety and exploratory behavior using an elevated plus maze and a novel object task as a control. Peri-adolescent mice were administered an acute intranasal (IN) treatment of 0.5 IU/kg IN AVP, 0.5 IU/kg IN OXT, or saline control; five minutes later, the behavioral tests were conducted. As predicted, we found that IN OXT enhanced social preference for parents; however, this was only in male and not female peri-adolescent mice. IN AVP did not influence social preference in either sex. These effects appear specific to social behavior and not anxiety, as neither IN OXT nor AVP influenced behavior during the elevated plus maze or novel object tasks. To our knowledge, this is the first evidence indicating that OXT may play a role in promoting peri-adolescent social preferences for parents and delaying weaning in males.

Peg Forest Rehabilitation - A novel spatial navigation based cognitive rehabilitation paradigm for experimental neurotrauma

Traumatic brain injury (TBI) results from mechanical forces applied to the head. Ensuing cascades of complex pathophysiology transition the injury event into a disease process. The enduring constellation of emotional, somatic, and cognitive impairments degrade quality of life for the millions of TBI survivors suffering from long-term neurological symptoms. Rehabilitation strategies have reported mixed results, as most have not focused on specific symptomatology or explored cellular processes. The current experiments evaluated a novel cognitive rehabilitation paradigm for brain-injured and uninjured rats. The arena is a plastic floor with a cartesian grid of holes for plastic dowels to create new environments with the rearrangement of threaded pegs. Rats received either two weeks of Peg Forest rehabilitation (PFR) or open field exposure starting at 7 days post-injury; or one week starting at either day 7 or 14 post-injury; or served as caged controls. Cognitive performance was assessed on a battery of novel object tasks at 28 days post-injury. The results revealed that two weeks of PFR was required to prevent the onset of cognitive impairments, while one week of PFR was insufficient regardless of when rehabilitation was initiated after injury. Further assessment of the task showed that novel daily arrangements of the environment were required to impart the cognitive performance benefits, as exposure to a static arrangement of pegs for PFR each day did not improve cognitive performance. The results indicate that PFR prevents the onset of cognitive disorders following acquired a mild to moderate brain injury, and potentially other neurological conditions.

Gut microbiome diversity and composition is associated with exploratory behavior in a wild-caught songbird

BACKGROUND

The gut microbiome influences its host in a myriad of ways, from immune system development to nutrient utilization. However, our understanding of the relationship between the gut microbiome and behavior, especially in wild species, is still poor. One behavior that potentially interacts with the gut microbiome is exploratory behavior, which animals use to acquire new information from the environment. We hypothesized that diversity of the gut microbiome will be correlated with exploratory behavior in a wild-caught bird species. To test this hypothesis, we captured wild house sparrows (Passer domesticus) and collected fecal samples to measure the diversity of their gut microbiomes. We then introduced individuals to a novel environment and measured their exploratory behavior.

RESULTS

We found that birds with higher alpha diversity of the gut microbiome exhibited higher exploratory behavior. These results suggest that high exploratory birds encounter more types of environmental microbes that contribute to their diverse gut microbiome compared with less exploratory birds. Alternatively, increased gut microbiome diversity may contribute to increased exploratory behavior. We also found differences in beta diversity when comparing high and low exploring birds, indicating differences in microbiome community structure. When comparing predicted functional pathways of the birds' microbiomes, we found that the microbiomes of high explorers contained more pathways involved in biofilm formation and xenobiotic degradation than those of low explorers.

CONCLUSIONS

Overall, we found that the alpha and beta diversity of the gut microbiome is correlated with exploratory behavior of house sparrows. The predicted functions of the gut microbiome from high explorers differs from that of low explorers. Our study highlights the importance of considering the gut microbiome when investigating animal behavior.

Beyond bold versus shy: Zebrafish exploratory behavior falls into several behavioral clusters and is influenced by strain and sex

Individual differences in exploratory behavior have been found across a range of taxa and are thought to contribute to evolutionary fitness. Animals that explore more of a novel environment and visit areas of high predation risk are considered bold, whereas animals with the opposite behavioral pattern are shy. Here, we determined whether this bimodal characterization of bold versus shy adequately captures the breadth of behavioral variation in zebrafish or if there are more than these two subtypes. To identify behavioral categories, we applied unsupervised machine to three-dimensional swim traces from over 400 adult zebrafish across four strains (AB, TL, TU, and WIK) and both sexes. We found that behavior stratified into four distinct clusters: previously described bold and shy behavior and two new behavioral types we call wall-huggers and active explorers. Clusters were stable across time and influenced by strain and sex where we found that TLs were shy, female TU fish were bold, male TU fish were active explorers, and male ABs were wall-huggers. Our work suggests that zebrafish exploratory behavior has greater complexity than previously recognized and lays the groundwork for the use of zebrafish in understanding the biological basis of individual differences in behavior.

Summary: Prior work described individual differences in zebrafish exploratory behavior as bold or shy. Here, we find four categories better describe their behavior: bold, shy, active explorers, and wall-huggers.

A new method to study learning and memory using spontaneous locomotor activity in an open-field arena

BACKGROUND

Reduced locomotion with repeated exposure to a novel environment is often used as a measure of the basic adaptive learning process of habituation. While this is a well-established and reliable measure of habituation, it is not useful for the investigation of neurobiological changes before and after habituation because of the uncontrolled differential activity levels in a novel versus habituated environment. In this study we report a behavioral method that uses spontaneous locomotion to measure habituation, in which the total spontaneous locomotion in an initially novel environment does not change with repeated testing but, the ratio of central to peripheral activity does change and is indicative of habituation. The test sessions are brief (5 min) and the locomotion is measured in 2 separate zones. The peripheral zone comprises 8/9 of the test arena and the central zone 1/9 of the arena.

RESULTS/COMPARISON WITH EXISTING METHODS

In contrast to methods that use between-session reductions in locomotion to assess habituation, this method employs brief test sessions in which overall activity between sessions does not change, but the distribution of locomotion in the periphery versus the central zone of the arena does change. The brevity of the test session also enables us to utilize post-trial drug treatment protocols to impact memory consolidation.

CONCLUSIONS

The progressive change in the central/peripheral activity ratio with repeated testing can be determined independently of total activity and provides a habituation acquisition function that permits the measurement of neurobiological changes without the complication of effects related to changes in locomotor activity per se. The present report also presents evidence that this method can be used with post-trial drug treatment protocols to study the learning and memory effects of the post-trial treatments without the use of explicit rewards and punishments.

Peer tutoring of computer programming increases exploratory behavior in children

There is growing interest in teaching computer science and programming skills in schools. Here we investigated the efficacy of peer tutoring, which is known to be a useful educational resource in other domains but never before has been examined in such a core aspect of applied logical thinking in children. We compared (a) how children (N = 42, age range = 7 years 1 month to 8 years 4 months) learn computer programming from an adult versus learning from a peer and (b) the effect of teaching a peer versus simply revising what has been learned. Our results indicate that children taught by a peer showed comparable overall performance-a combination of accuracy and response times-to their classmates taught by an adult. However, there was a speed-accuracy trade-off, and peer-taught children showed more exploratory behavior, with shorter response times at the expense of lower accuracy. In contrast, no tutor effects (i.e., resulting from teaching a peer) were found. Thus, our results provide empirical evidence in support of peer tutoring as a way to help teach computer programming to children. This could contribute to the promotion of a widespread understanding of how computers operate and how to shape them, which is essential to our values of democracy, plurality, and freedom.

Information transmission in mPFC-BLA network during exploratory behavior in the open field

Exploratory behavior plays a fundamental role in motivation, learning, and well-being of organisms. The open field test (OFT) is a classic method to investigate the exploratory behavior in rodents, also a widely adopted and pharmacologically validated procedure for evaluating anxiety and depression. Several lines of evidence have shown that medial prefrontal cortex (mPFC) and basolateral amygdala (BLA) play crucial roles in anxiety-like or depression-like exploratory behavior. However, the dynamic characterization of the mPFC-BLA network in exploratory behavior is less well understood. Therefore, this study aimed to investigate the information transmission mechanism in the mPFC-BLA network during exploratory behavior. Local field potentials (LFPs) from mPFC and BLA were simultaneously recorded while the rats performed the OFT. Directed transfer function (DTF), which was derived from Granger causal connectivity analysis, was applied to measure the functional connectivity among LFPs. Information flow (IF) was calculated to explore the dynamics of information transmission in the mPFC-BLA network. Our results revealed that, for both mPFC and BLA, the theta-band functional connectivity in periphery was significantly higher than that in center of the open field. The IF from BLA to mPFC in the open field task was significantly higher than that from mPFC to BLA. These results suggest that the functional connectivity and IF in the mPFC-BLA network are related to the exploratory behavior, and information transmission from BLA to mPFC could be predominant for exploratory behavior.

Loss of Calretinin in L5a impairs the formation of the barrel cortex leading to abnormal whisker-mediated behaviors

The rodent whisker-barrel cortex system has been established as an ideal model for studying sensory information integration. The barrel cortex consists of barrel and septa columns that receive information input from the lemniscal and paralemniscal pathways, respectively. Layer 5a is involved in both barrel and septa circuits and play a key role in information integration. However, the role of layer 5a in the development of the barrel cortex remains unclear. Previously, we found that calretinin is dynamically expressed in layer 5a. In this study, we analyzed calretinin KO mice and found that the dendritic complexity and length of layer 5a pyramidal neurons were significantly decreased after calretinin ablation. The membrane excitability and excitatory synaptic transmission of layer 5a neurons were increased. Consequently, the organization of the barrels was impaired. Moreover, layer 4 spiny stellate cells were not able to properly gather, leading to abnormal formation of barrel walls as the ratio of barrel/septum size obviously decreased. Calretinin KO mice exhibited deficits in exploratory and whisker-associated tactile behaviors as well as social novelty preference. Our study expands our knowledge of layer 5a pyramidal neurons in the formation of barrel walls and deepens the understanding of the development of the whisker-barrel cortex system.

Exposure to bacterial lipopolysaccharidein early life affects the expression of ionotropic glutamate receptor genes and is accompanied by disturbances in long-term potentiation and cognitive functions in young rats

Infections in childhood play an essential role in the pathogenesis of cognitive and psycho-emotional disorders. One of the possible mechanisms of these impairments is changes in the functional properties of NMDA and AMPA glutamate receptors in the brain. We suggest that bacterial infections during the early life period, which is critical for excitatory synapse maturation, can affect the subunit composition of NMDA and AMPA receptors. In the present study, we investigated the effect of repetitive lipopolysaccharide (LPS) intraperitoneal (i.p.) administration (25 μg/kg/day on P14, 16, and 18), mimicking an infectious disease, on the expression of subunits of NMDA and AMPA receptors in young rats. We revealed a substantial decrease of GluN2B subunit expression in the hippocampus at P23 using Western blot analysis and real-time polymerase chain reaction assay. Moderate changes were also found in GluN1, GluN2A, and GluA1 mRNA expression. The LPS-treated rats exhibited decreased exploratory and locomotor activity in the open field test and the impairment of spatial learning in the Morris water maze. Behavioral impairments were accompanied by a significant reduction in long-term hippocampal synaptic potentiation. Our data indicate that LPS-treatment in the critical period for excitatory synapse maturation alters ionotropic glutamate receptor gene expression, disturbs synaptic plasticity, and alters behavior.

Intravenous infusion of bone marrow mononuclear cells promotes functional recovery and improves impaired cognitive function via inhibition of Rho guanine nucleotide triphosphatases and inflammatory signals in a model of chronic epilepsy

Temporal lobe epilepsy is the most common form of intractable epilepsy in adults. More than 30% of individuals with epilepsy have persistent seizures and have drug-resistant epilepsy. Based on our previous findings, treatment with bone marrow mononuclear cells (BMMC) could interfere with early and chronic phase epilepsy in rats and in clinical settings. In this pilocarpine-induced epilepsy model, animals were randomly assigned to two groups: control (Con) and epileptic pre-treatment (Ep-pre-t). The latter had status epilepticus (SE) induced through pilocarpine intraperitoneal injection. Later, seizure frequency was assessed using a video-monitoring system. Ep-pre-t was further divided into epileptic treated with saline (Ep-Veh) and epileptic treated with BMMC (Ep-BMMC) after an intravenous treatment with BMMC was done on day 22 after SE. Analysis of neurobehavioral parameters revealed that Ep-BMMC had significantly lower frequency of spontaneous recurrent seizures (SRS) in comparison to Ep-pre-t and Ep-Veh groups. Hippocampus-dependent spatial and non-spatial learning and memory were markedly impaired in epileptic rats, a deficit that was robustly recovered by treatment with BMMC. Moreover, long-term potentiation-induced synaptic remodeling present in epileptic rats was restored by BMMC. In addition, BMMC was able to reduce abnormal mossy fiber sprouting in the dentate gyrus. Molecular analysis in hippocampal tissue revealed that BMMC treatment down-regulates the release of inflammatory cytokine tumor necrosis factor-α (TNF-α) and Allograft inflammatory factor-1 (AIF-1) as well as the Rho subfamily of small GTPases [Ras homolog gene family member A (RhoA) and Ras-related C3 botulinum toxin substrate 1 (Rac)]. Collectively, delayed BMMC treatment showed positive effects when intravenously infused into chronic epileptic rats.

Familiarization effects on the behavioral disinhibition of the cerebellar Lurcher mutant mice: use of the innovative Dual Maze

Anxiety-related behaviors in mice are often assessed over short periods starting immediately after introducing the animals in a dedicated apparatus. In these usual conditions (5-10 min periods), the cerebellar Lurcher mutants showed disinhibited behaviors characterized by abnormally high exploration of the aversive areas in the elevated plus-maze test. We nevertheless observed that this disinhibition sharply weakened after 10 min. We therefore decided to further investigate the influence of the disinhibition on the intrinsic and anxiety-related exploratory behaviors in Lurcher mice, with a special focus on familiarization effects. To this end, we used an innovative apparatus, the Dual Maze, permitting to tune the familiarization level of animals to the experimental context before they are faced with more (open configuration of the device) or less (closed configuration of the device) aversive areas. Chlordiazepoxide administration in BALB/c mice in a preliminary experiment confirmed both the face and the predictive validity of our device as anxiety test and its ability to measure exploratory motivation. The results obtained with the Lurcher mice in the open configuration revealed that 20 min of familiarization to the experimental context abolished the behavioral abnormalities they exhibited when not familiarized with it. In addition, their exploratory motivation, as measured in the closed configuration, was comparable to that of their non-mutant littermates, whatever the level of familiarization applied. Exemplifying the interest of this innovative device, the results we obtained in the Lurcher mutants permitted to differentiate between the roles played by the cerebellum in exploratory motivation and stress-related behaviors.

Incubation temperature and satiety influence general locomotor and exploratory behaviors in the common snapping turtle (Chelydra serpentina)

Temperature during embryogenesis determines sex and has been shown to influence other physiological traits in reptiles. The common snapping turtle (Chelydra serpentina) is an ideal model for testing how temperature impacts behavior in species that display temperature-dependent sex determination. Behavioral assays are crucial to understanding how a changing climate may affect whole organism function in the snapping turtle. Currently, there are few behavioral assays for semi-aquatic vertebrates like turtles. In this study, we used digital cameras to record behavior of fed and fasted hatchling turtles from different incubation temperatures in an open field setting for 20 min in 2018 and repeated the experiment in 2019. Open fields were circular tanks filled with water to a depth of 3.5 cm. Each field was split into four quadrants and two zones (inner and outer). The amount of time turtles spent actively moving, total distance travelled, and several other measures were collected and summarized automatically from videos with open source image analysis software (ImageJ). Satiety and incubation temperature had significant effects on total distance moved, time spent moving, and time moving in the outer zone. These findings indicate that temperature during embryogenesis has a long-lasting effect on neural mechanisms underlying exploratory or general locomotor behavior in turtles.

Sex differences in cognitive performance and alcohol consumption in High Alcohol-Drinking (HAD-1) rats

Excessive alcohol (ethanol) consumption negatively impacts social, emotional, as well as cognitive function and well-being. Thus, identifying behavioral and/or biological predictors of excessive ethanol consumption is important for developing prevention and treatment strategies against alcohol use disorders (AUDs). Sex differences in alcohol consumption patterns are observed in humans, primates, and rodents. Selectively bred high alcohol-drinking rat lines, such as the "HAD-1" lines are recognized animal models of alcoholism. The present work examined sex differences in alcohol consumption, object recognition, and exploratory behavior in male and female HAD-1 rats. Naïve male and female HAD-1 rats were tested in an object recognition test (ORT) prior to a chronic 24 h intermittent ethanol access procedure for five weeks. Object recognition parameters measured included exploratory behavior, object investigation, and time spent near objects. During the initial training trial, rearing, active object investigation and amount of time spent in the object-containing section was significantly greater in female HAD-1 rats compared to their male counterparts. During the subsequent testing trial, time spent in the object-containing section was greater in female, compared to male, rats; but active object investigation and rearing did not statistically differ between females and males. In addition, female HAD-1 rats consumed significantly more ethanol than their male counterparts, replicating previous findings. Moreover, across all animals there was a significant positive correlation between exploratory behavior in ORT and ethanol consumption level. These results indicate there are significant sex differences in cognitive performance and alcohol consumption in HAD-1 rats, which suggests neurobiological differences as well.

A longitudinal examination of the role of sensory exploratory behaviors in young children's acceptance of new foods

OBJECTIVE

Prompted engagement with a new food's sensory properties (smell, texture) has been associated with young children's acceptance of new foods. However, little is known about the prevalence and stability of children's sensory exploratory behaviors exhibited spontaneously when trying new foods. The aim of this analysis was to examine developmental trajectories of sensory exploratory behaviors (i.e., smelling, licking, spitting) in response to new foods.

METHOD

This 3-year longitudinal study included observational data collected from 244 preschoolers. At age 4 years, children were asked to taste four novel foods. An experimenter recorded the child's displays of smelling, licking, spitting, refusals, and acceptance. Assessments were repeated at 4.5, 5.5, and 6.5 years of age. Summary scores were created for each child by totaling the number of foods smelled, licked, spit out, refused, and accepted at each time point. A series of growth models were fit to the summary scores to examine individual sensory behavior trajectories and associations between trajectories of sensory behaviors and acceptance.

RESULTS

Linear growth model parameters indicated that spitting and refusals decreased over time (p-values < 0.01), whereas acceptances increased (p < 0.01). Licking and smelling showed non-significant change (p-values > 0.01) Furthermore, decreases in licking, spitting, and refusals were associated with increases in acceptance across the study period (p-values < 0.01).

DISCUSSION

The decline in young children's sensory exploratory behaviors in response to new foods was associated with increases in food acceptance. Our findings suggest that sensory exploratory behaviors may promote familiarity and help children learn that new foods are acceptable and safe to consume.

Cacna1b alternative splicing impacts excitatory neurotransmission and is linked to behavioral responses to aversive stimuli

Presynaptic CaV2.2 channels control calcium entry that triggers neurotransmitter release at both central and peripheral synapses. The Cacna1b gene encodes the α1-pore forming subunit of CaV2.2 channels. Distinct subsets of splice variants of CaV2.2 derived from cell-specific alternative splicing of the Cacna1b pre-mRNA are expressed in specific subpopulations of neurons. Four cell-specific sites of alternative splicing in Cacna1b that alter CaV2.2 channel function have been described in detail: three cassette exons (e18a, e24a, and e31a) and a pair of mutually exclusive exons (e37a/e37b). Cacna1b mRNAs containing e37a are highly enriched in a subpopulation of nociceptors where they influence nociception and morphine analgesia. E37a-Cacna1b mRNAs are also expressed in brain, but their cell-specific expression in this part of the nervous system, their functional consequences in central synapses and their role on complex behavior have not been studied. In this report, we show that e37a-Cacna1b mRNAs are expressed in excitatory projection neurons where CaV2.2 channels are known to influence transmitter release at excitatory inputs from entorhinal cortex (EC) to dentate gyrus (DG). By comparing behaviors of WT mice to those that only express e37b-CaV2.2 channels, we found evidence that e37a-CaV2.2 enhances behavioral responses to aversive stimuli. Our results suggest that alternative splicing of Cacna1b e37a influences excitatory transmitter release and couples to complex behaviors.

The effects of fluorene-9-bisphenol on female zebrafish (Danio rerio) reproductive and exploratory behaviors

Endocrine disruptor chemicals induce adverse effects to animals' development, reproduction and behavior in environment. We investigated the effects of fluorene-9-bisphenol (BHPF), one substitute of bisphenol A, on courtship behavior and exploratory behavior of adult zebrafish. Customized apparatus was used to evaluate courtship behavior. The result showed that the male spent less time with BHPF and anti-oestrogenic fulvestrant (FULV) treated female in region of approaching (ROA). Courtship index between BHPF-exposed female and male decreased. The body orientation of BHPF- and FULV-exposed female to male decreased. Furthermore, BHPF exposure downregulated the expression of genes related to estrogen receptor, steroidogenesis and upregulated oxidative stress related genes. It indicated that BHPF exposure interfered the preference of male and female in courtship, and induced detrimental effects on reproduction. BHPF treatment decreased locomotor activity and time spent in top, increased freezing bouts, and induced anxiety/depression-like behavior. The tyrosine hydroxylase in brain decreased under BHPF exposure. Here we showed the potential adverse effects of BHPF on reproduction and exploratory behaviors.

Comorbidities of early-onset temporal epilepsy: Cognitive, social, emotional, and morphologic dimensions

Epilepsy, the most common neurologic disorder in childhood, is associated with a subset of psychiatric dysfunctions, including cognitive deficits, and alterations in emotionality (e.g., anxiety and depression) and social functioning. In the present study, we evaluated an integrative set of behavioral responses, including cognitive/socio-cognitive and emotional dimensions, using a number of behavioral paradigms in the LiCl/pilocarpine model of status epilepticus (SE) in rats. The aims of the study were to examine whether SE affects: 1) non-associative learning (habituation of exploratory behavior); 2) investigatory response to an indifferent stimulus object; 3) sociability/social novelty preference; 4) social recognition or discrimination; and 4) short- and long-term memory in the Morris water maze (MWM). Finally, we investigated the morphology of key brain structures involved in the examined behavioral dysfunctions. SE did not affect habituation to an open-field arena in juvenile (P25), adolescent (P32), or adult (P80) rats. SE rats spent less time in the central part of the arena. SE adolescent rats (P32) displayed a higher number of rearings with a shorter duration. SE rats displayed a markedly attenuated investigatory response to an indifferent stimulus object. SE rats in all age groups demonstrated pronounced deficits in sociability and the preference for social novelty. In addition, SE rats spent a reduced amount of time investigating a juvenile rat upon first exposure. After 30 min re-exposure together with an additional, novel juvenile, the SE rats spent equal time investigating both juveniles. In the MWM task, acquisition was unimpaired but there was a deficit in delayed memory retention after 10 days. SE did not affect cognitive flexibility expressed by reversal learning. Together, these findings suggest that early-life SE leads to alterations in emotional/anxiety-related behavior and affects sociability/preference for social novelty and social discrimination. Early-life SE did not alter acquisition of spatial learning, but it impaired delayed retention. Using Fluoro Jade B staining performed 24 h after SE revealed apparent neurodegeneration in the dorsal hippocampus, mediodorsal thalamic nucleus and medial amygdala, brain areas that are critically involved in network underlying emotional behavior and cognitive functions.

Selective maintenance of value information helps resolve the exploration/exploitation dilemma

In natural environments with many options of uncertain value, one faces a difficult tradeoff between exploiting familiar, valuable options or searching for better alternatives. Reinforcement learning models of this exploration/exploitation dilemma typically modulate the rate of exploratory choices or preferentially sample uncertain options. The extent to which such models capture human behavior remains unclear, in part because they do not consider the constraints on remembering what is learned. Using reinforcement-based timing as a motivating example, we show that selectively maintaining high-value actions compresses the amount of information to be tracked in learning, as quantified by Shannon's entropy. In turn, the information content of the value representation controls the balance between exploration (high entropy) and exploitation (low entropy). Selectively maintaining preferred action values while allowing others to decay renders the choices increasingly exploitative across learning episodes. To adjudicate among alternative maintenance and sampling strategies, we developed a new reinforcement learning model, StrategiC ExPloration/ExPloitation of Temporal Instrumental Contingencies (SCEPTIC). In computational studies, a resource-rational selective maintenance approach was as successful as more resource-intensive strategies. Furthermore, human behavior was consistent with selective maintenance; information compression was most pronounced in subjects with superior performance and non-verbal intelligence, and in learnable vs. unlearnable contingencies. Cognitively demanding uncertainty-directed exploration recovered a more accurate representation in simulations with no foraging advantage and was strongly unsupported in our human study.

Intracerebellar microinjection of histaminergic compounds on locomotor and exploratory behaviors in mice

The neural histaminergic system innervates the cerebellum, with a high density of fibers in the vermis and flocculus. The cerebellum participates in motor functions, but the role of the histaminergic system in this function is unclear. In the present study, we investigated the effects of intracerebellar histamine injections and H1, H2 and H3 receptor antagonist injections (chlorpheniramine, ranitidine, and thioperamide, respectively) and H4 receptor agonist (VUF-8430) on locomotor and exploratory behaviors in mice. The cerebellar vermis of male mice was implanted with guide cannula. After three days of recovery,the animals received microinjections of saline or histamine (experiment1), saline or chlorpheniramine (experiment 2), saline or ranitidine(experiment 3), saline or thioperamide (experiment 4), and saline or VUF-8430 (experiment 5) in different concentrations. Five minutes postinjection,the open field test was performed. The data were analyzed using one-way ANOVA and Duncan's post hoc test. The microinjections of histamine, ranitidine or thioperamide did not lead any behavioral effects at the used doses. In contrast, animals that received chlorpheniramine at the highest dose (0.16 nmol) and VUF-8430 at the highest dose (1.48 nmol)were more active in the open field apparatus, with an increase in the number of crossed quadrants, number of rearings and time spent in the central area of the arena, suggesting that chlorpheniramine and VUF-8430 modulates locomotor and exploratory behaviors in mice.

Characterization of sickness behavior in zebrafish

In a previous study we showed a clear relationship between immune system and behavior in zebrafish and we hypothesized that the immune system is capable of inducing behavioral changes. To further investigate this subject and to address our main question, here we induced an inflammatory response in one group of fish by the inoculation of formalin-inactivated Aeromonoas hydrophila bacterin and compared their social and exploratory behavior with control groups. After the behavioral tests, we also analyzed the expression of cytokines genes and markers of neuronal activity in fish brain. In the bacterin-inoculated fish, the locomotor activity, social preference and exploratory behavior towards a new object were reduced compared to the control fish while the expression of proinflammatory cytokines in the brain was upregulated. With this study we demonstrated for the first time that the immune system is capable of causing behavioral changes that are consistent with the sickness behavior observed in mammals.

The effects of auditory enrichment on zebrafish behavior and physiology

Environmental enrichment is widely used to improve welfare and behavioral performance of animal species. It ensures housing of laboratory animals in environments with space and complexity that enable the expression of their normal behavioral repertoire. Auditory enrichment by exposure to classical music decreases abnormal behaviors and endocrine stress responses in humans, non-humans primates, and rodents. However, little is known about the role of auditory enrichment in laboratory zebrafish. Given the growing importance of zebrafish for neuroscience research, such studies become critical. To examine whether auditory enrichment by classical music can affect fish behavior and physiology, we exposed adult zebrafish to 2 h of Vivaldi’s music (65–75 dB) twice daily, for 15 days. Overall, zebrafish exposed to such auditory stimuli were less anxious in the novel tank test and less active, calmer in the light-dark test, also affecting zebrafish physiological (immune) biomarkers, decreasing peripheral levels of pro-inflammatory cytokines and increasing the activity of some CNS genes, without overt effects on whole-body cortisol levels. In summary, we report that twice-daily exposure to continuous musical sounds may provide benefits over the ongoing 50–55 dB background noise of equipment in the laboratory setting. Overall, our results support utilizing auditory enrichment in laboratory zebrafish to reduce stress and improve welfare in this experimental aquatic organism.

Fourteen-month-olds selectively search for and use information depending on the familiarity of the informant in both laboratory and home contexts

Infants are selective in their learning from others. However, there is only very limited research on the possible factors that shape this selectivity, especially when it comes to the impact of infants' familiarity with the informant and the context. The current study investigated whether 14-month-olds preferred to receive and use information provided by an unfamiliar informant (experimenter) compared with a familiar informant (parent) and whether this pattern depended on the context (home vs. laboratory). We tested infants either in the laboratory (n = 67) or in their home (n = 70). When both informants presented a novel object with positive or negative emotions, we measured infants' gaze behavior as an indicator for information search. When infants acted on the novel object themselves, we measured their exploratory behavior as an indicator of information use. Results revealed no effect of context on infants' information search and use. Rather, we found that the familiarity of informant had distinct effects on infant attention and object exploration. Namely, infants looked longer at the unfamiliar informant across contexts, but they explored more when the familiar informant presented the object compared with when the unfamiliar informant did so. Thus, during information search, 14-month-olds paid most attention to an unfamiliar source of information. However, participants explored the objects more when they came from a familiar source than when they came from an unfamiliar one. Possible explanations for these findings are discussed.

Exploratory behavior is linked to stress physiology and social network centrality in free-living house finches (Haemorhous mexicanus)

Animal personality has been linked to individual variation in both stress physiology and social behaviors, but few studies have simultaneously examined covariation between personality traits, stress hormone levels, and behaviors in free-living animals. We investigated relationships between exploratory behavior (one aspect of animal personality), stress physiology, and social and foraging behaviors in wild house finches (Haemorhous mexicanus). We conducted novel environment assays after collecting samples of baseline and stress-induced plasma corticosterone concentrations from a subset of house finches. We then fitted individuals with Passive Integrated Transponder tags and monitored feeder use and social interactions at radio-frequency identification equipped bird feeders. First, we found that individuals with higher baseline corticosterone concentrations exhibit more exploratory behaviors in a novel environment. Second, more exploratory individuals interacted with more unique conspecifics in the wild, though this result was stronger for female than for male house finches. Third, individuals that were quick to begin exploring interacted more frequently with conspecifics than slow-exploring individuals. Finally, exploratory behaviors were unrelated to foraging behaviors, including the amount of time spent on bird feeders, a behavior previously shown to be predictive of acquiring a bacterial disease that causes annual epidemics in house finches. Overall, our results indicate that individual differences in exploratory behavior are linked to variation in both stress physiology and social network traits in free-living house finches. Such covariation has important implications for house finch ecology, as both traits can contribute to fitness in the wild.

Risky business: Changes in boldness behavior in male Siamese fighting fish, Betta splendens, following exposure to an antiandrogen

Components of boldness, such as activity level and locomotion, influence an individual's ability to avoid predators and acquire resources, generating fitness consequences. The presence of endocrine disrupting chemicals (EDCs) in the aquatic environment may affect fitness by changing morphology or altering behaviors like courtship and exploration. Most research on EDC-generated behavioral effects has focused on estrogen mimics and reproductive endpoints. Far fewer studies have examined the effects of other types of EDCs or measured non-reproductive behaviors. EDCs with antiandrogenic properties are present in waterways yet we know little about their effects on exposed individuals although they may produce effects similar to those caused by estrogen mimics because they act on the same hormonal pathway. To examine the effects of antiandrogens on boldness, this study exposed male Siamese fighting fish, Betta splendens, to a high or low dose of one of two antiandrogens, vinclozolin or flutamide, and observed behavior in three boldness assays, both before and after exposure. Overall, antiandrogen exposure increased boldness behavior, especially following exposure to the higher dose. Whether or not antiandrogen exposure influenced boldness, as well as the nature and intensity of the effect, was assay-dependent. This demonstrates the importance of studying EDC effects in a range of contexts and, at least within this species, suggests that antiandrogenic compounds may generate distinct physiological effects in different situations. How and why the behavioral effects differ from those caused by exposure to an estrogen mimic, as well as the potential consequences of increased activity levels, are discussed. Exposure to an antiandrogen, regardless of dose, produced elevated activity levels and altered shoaling and exploration in male Siamese fighting fish. These modifications may have fitness consequences.

Exploratory behaviors and recalibration: What processes are shared between functionally similar affordances?

Recalibration of affordance perception allows observers to adapt to changes in the body's size or abilities that alter possibilities for action. Of key interest is understanding how exploratory behaviors lead to successful recalibration. The present study was designed to test a novel hypothesis-that the same processes of exploration and recalibration should generalize between affordances that share a similar function. Most affordances for fitting the body through openings are recalibrated without feedback from practicing the action; locomotion exploration is sufficient. The present study used a different fitting task, squeezing through doorways, to determine whether locomotor experience was sufficient for recalibrating to changes in body size that altered affordances. Participants were unable to recalibrate from locomotor experience, demonstrating that exploratory behaviors do not necessarily generalize between functionally similar affordances. Participants only recalibrated following action practice or after receiving feedback about judgment accuracy, suggesting that the informational requirements of the squeezing task may differ from those of other fitting tasks. Implications for affordance theory are discussed.

Intraspecific variation in exploratory behavior and elevational affinity in a widely distributed songbird

Populations of the same species can vary substantially in their behavioral and morphometric traits when they are subject to different environmental pressures, which may lead to the development of different adaptive strategies. We quantified variation in exploratory behavior and morphometric traits among two rufous-collared sparrow populations that occur at low and high elevations in central Chile. Moreover, we used census and δ²H values of feather and blood to evaluate migration. We found that individual sparrows inhabiting high elevations were larger and showed more intense exploratory behavior in comparison with those that were captured at lower elevation. Moreover, we observed a steady decline in sparrow abundance during the winter and similar δ²H values for blood collected in the winter and summer at this site, which were significantly lower than blood δ²H values observed at low elevation. This pattern suggests that individuals do not move long distances during winter, and likely they remain at similar elevations in refuge habitats. As predicted, our results support the existent of different adaptive strategies among populations of the same species, and suggest that the combination of behavioral, morphometric, and stable isotope data is a novel and robust integrative approach to assess differences in adaptation across environmental gradients.

Oxytocin modulates human communication by enhancing cognitive exploration

Oxytocin is a neuropeptide known to influence how humans share material resources. Here we explore whether oxytocin influences how we share knowledge. We focus on two distinguishing features of human communication, namely the ability to select communicative signals that disambiguate the many-to-many mappings that exist between a signal's form and meaning, and adjustments of those signals to the presumed cognitive characteristics of the addressee ("audience design"). Fifty-five males participated in a randomized, double-blind, placebo controlled experiment involving the intranasal administration of oxytocin. The participants produced novel non-verbal communicative signals towards two different addressees, an adult or a child, in an experimentally-controlled live interactive setting. We found that oxytocin administration drives participants to generate signals of higher referential quality, i.e. signals that disambiguate more communicative problems; and to rapidly adjust those communicative signals to what the addressee understands. The combined effects of oxytocin on referential quality and audience design fit with the notion that oxytocin administration leads participants to explore more pervasively behaviors that can convey their intention, and diverse models of the addressees. These findings suggest that, besides affecting prosocial drive and salience of social cues, oxytocin influences how we share knowledge by promoting cognitive exploration.

Assessing Mongolian gerbil emotional behavior: effects of two shock intensities and response-independent shocks during an extended inhibitory-avoidance task

Despite step-down inhibitory avoidance procedures that have been widely implemented in rats and mice to study learning and emotion phenomena, performance of other species in these tasks has received less attention. The case of the Mongolian gerbil is of relevance considering the discrepancies in the parameters of the step-down protocols implemented, especially the wide range of foot-shock intensities (i.e., 0.4–4.0 mA), and the lack of information on long-term performance, extinction effects, and behavioral patterning during these tasks. Experiment 1 aimed to (a) characterize gerbils’ acquisition, extinction, and steady-state performance during a multisession (i.e., extended) step-down protocol adapted for implementation in a commercially-available behavioral package (Video Fear Conditioning System—MED Associates Fairfax, VT, USA), and (b) compare gerbils’ performance in this task with two shock intensities – 0.5 vs. 1.0 mA—considered in the low-to-mid range. Results indicated that the 1.0 mA protocol produced more reliable and clear evidence of avoidance learning, extinction, and reacquisition in terms of increments in freezing and on-platform time as well as suppression of platform descent. Experiment 2 aimed to (a) assess whether an alternate protocol consisting of a random delivery of foot shocks could replicate the effects of Experiment 1 and (b) characterize gerbils’ exploratory behavior during the step-down task (jumping, digging, rearing, and probing). Random shocks did not reproduce the effects observed with the first protocol. The data also indicated that a change from random to response-dependent shocks affects (a) the length of each visit to the platform, but not the frequency of platform descends or freezing time, and (b) the patterns of exploratory behavior, namely, suppression of digging and rearing, as well as increments in probing and jumping. Overall, the study demonstrated the feasibility of the extended step-down protocol for studying steady performance, extinction, and reacquisition of avoidance behavior in gerbils, which could be easily implemented in a commercially available system. The observation that 1.0 mA shocks produced a clear and consistent avoidance behavior suggests that implementation of higher intensities is unnecessary for reproducing aversive-conditioning effects in this species. The observed patterning of freezing, platform descents, and exploratory responses produced by the change from random to periodic shocks may relate to the active defensive system of the gerbil. Of special interest is the probing behavior, which could be interpreted as risk assessment and has not been reported in other rodent species exposed to step-down and similar tasks.

Sexual dimorphisms in swimming behavior, cerebral metabolic activity and adrenoceptors in adult zebrafish (Danio rerio)

Sexually dimorphic behaviors and brain sex differences, not only restricted to reproduction, are considered to be evolutionary preserved. Specifically, anxiety related behavioral repertoire is suggested to exhibit sex-specific characteristics in rodents and primates. The present study investigated whether behavioral responses to novelty, have sex-specific characteristics in the neurogenetic model organism zebrafish (Danio rerio), lacking chromosomal sex determination. For this, aspects of anxiety-like behavior (including reduced exploration, increased freezing behavior and erratic movement) of male and female adult zebrafish were tested in a novel tank paradigm and after habituation. Male and female zebrafish showed significant differences in their swimming activity in response to novelty, with females showing less anxiety spending more time in the upper tank level. When fish have habituated, regional cerebral glucose uptake, an index of neuronal activity, and brain adrenoceptors' (ARs) expression (α2-ARs and β-ARs) were determined using in vivo 2-[(14)C]-deoxyglucose methodology and in vitro neurotransmitter receptors quantitative autoradiography, respectively. Intriguingly, females exhibited higher glucose utilization than males in hypothalamic brain areas. Adrenoceptor's expression pattern was dimorphic in zebrafish telencephalic, preoptic, hypothalamic nuclei, central gray, and cerebellum, similarly to birds and mammals. Specifically, the lateral zone of dorsal telencephalon (Dl), an area related to spatial cognition, homologous to the mammalian hippocampus, showed higher α2-AR densities in females. In contrast, male cerebellum included higher densities of β-ARs in comparison to female. Taken together, our data demonstrate a well-defined sex discriminant cerebral metabolic activity and ARs' pattern in zebrafish, possibly contributing to male-female differences in the swimming behavior.

Effect of behavioral testing on spine density of basal dendrites in the CA1 region of the hippocampus modulated by (56)Fe irradiation

A unique feature of the space radiation environment is the presence of high-energy charged particles, including (56)Fe ions, which can present a significant hazard to space flight crews during and following a mission. (56)Fe irradiation-induced cognitive changes often involve alterations in hippocampal function. These alterations might involve changes in spine morphology and density. In addition to irradiation, performing a cognitive task can also affect spine morphology. Therefore, it is often hard to determine whether changes in spine morphology and density are due to an environmental challenge or group differences in performance on cognitive tests. In this study, we tested the hypothesis that the ability of exploratory behavior to increase specific measures of hippocampal spine morphology and density is affected by (56)Fe irradiation. In sham-irradiated mice, exploratory behavior increased basal spine density in the CA1 region of the hippocampus and the enclosed blade of the dentate gyrus. These effects were not seen in irradiated mice. In addition, following exploratory behavior, there was a trend toward a decrease in the percent stubby spines on apical dendrites in the CA3 region of the hippocampus in (56)Fe-irradiated, but not sham-irradiated, mice. Other hippocampal regions and spine measures affected by (56)Fe irradiation showed comparable radiation effects in behaviorally naïve and cognitively tested mice. Thus, the ability of exploratory behavior to alter spine density and morphology in specific hippocampal regions is affected by (56)Fe irradiation.

Clinically effective OCD treatment prevents 5-HT1B receptor-induced repetitive behavior and striatal activation

RATIONALE

Serotonin-1B receptor (5-HT1BR) agonist treatment induces obsessive-compulsive disorder (OCD)-like behaviors including locomotor stereotypy, prepulse inhibition deficits, and delayed alternation disruptions, which are selectively prevented by clinically effective OCD treatment. However, the role of 5-HT1BRs in modulating other repetitive behaviors or OCD-like patterns of brain activation remains unclear.

OBJECTIVES

We assessed the effects of 5-HT1BR agonism on digging, grooming, and open field behaviors in mice. We also quantified effects on neuronal activation in brain regions overactivated in OCD. Finally, we assessed whether effects of the 5-HT1BR challenge could be blocked by clinically effective, but not ineffective, drug treatments.

METHODS

Mice were tested in open field, dig, and splash tests after acute treatment with saline, 1, 3, 5, or 10 mg/kg RU24969 (5-HT1B/1A agonist). Behavioral effects of RU24969 were also tested following co-treatment with vehicle, 1 mg/kg WAY100635 (5-HT1A antagonist) and 5 or 10 mg/kg GR127935 (5HT1B/D antagonist). Separate mice were behaviorally assessed following chronic pretreatment with vehicle with 10 mg/kg fluoxetine or 20 mg/kg desipramine and acute treatment with saline or 10 mg/kg RU24969. Brains were analyzed for Fos expression in the orbitofrontal cortex, the dorsal striatum, and the cerebellum.

RESULTS

RU24969 induced robust locomotor stereotypy and decreased rearing, digging, and grooming. Effects were blocked by GR127935 but not by WAY100635. RU24969 also increased Fos expression in the dorsal striatum. Chronic fluoxetine, but not desipramine, alleviated 5-HT1BR-induced effects.

CONCLUSIONS

We report novel 5-HT1BR-induced behaviors and striatal activation that were alleviated only by clinically effective pharmacological OCD treatment. Studying the mechanisms underlying these effects could provide insight into OCD pathophysiology.

Protocols to Study Behavior in Drosophila

Drosophila melanogaster is an incredibly versatile organism capable of both innate and higher-order behaviors. These behaviors offer not only a way to assay whether or not the animal is physiologically compromised (e.g., feeding, locomotion), but also serve to assess changes in centrally mediated functions. Here we describe several high throughput, reproducible, yet inexpensive and facile behavioral assays for both larval and adult Drosophila. The larval assays all employ an agar substrate in a petri dish; the adult assays are grouped into "vial-based" and "arena-based" paradigms. While these protocols are largely designed to assess individual animals, they are sufficiently rapid that ample numbers can be tested to determine behavioral significance. Importantly, this also allows for one to control for reproductive status, age, and sex, since these factors all have a significant impact on adult behaviors. In general, it is best to designate a dedicated area for any assay, so that lighting conditions are consistent, and all animals should be tested at roughly the same time each day to minimize circadian fluctuations. Temperature and humidity should also be maintained at a constant level to minimize variability in the assays.

Interaction between CHL1 and serotonin receptor 2c regulates signal transduction and behavior in mice

The serotonergic system plays important roles in multiple functions of the nervous system and its malfunctioning leads to neurological and psychiatric disorders. Here, we show that the cell adhesion molecule close homolog of L1 (CHL1), which has been linked to mental disorders, binds to a peptide stretch in the third intracellular loop of the serotonin 2c (5-HT2c) receptor through its intracellular domain. Moreover, we provide evidence that CHL1 deficiency in mice leads to 5-HT2c-receptor-related reduction in locomotor activity and reactivity to novelty, and that CHL1 regulates signaling pathways triggered by constitutively active isoforms of the 5-HT2c receptor. Furthermore, we found that the 5-HT2c receptor and CHL1 colocalize in striatal and hippocampal GABAergic neurons, and that 5-HT2c receptor phosphorylation and its association with phosphatase and tensin homolog (PTEN) and β-arrestin 2 is regulated by CHL1. Our results demonstrate that CHL1 regulates signal transduction pathways through constitutively active 5-HT2c receptor isoforms, thereby altering 5-HT2c receptor functions and implicating CHL1 as a new modulator of the serotonergic system.

Astrocytic IL-6 mediates locomotor activity, exploration, anxiety, learning and social behavior

Interleukin-6 (IL-6) is a major cytokine in the central nervous system, secreted by different brain cells and with roles in a number of physiological functions. We herewith confirm and expand the importance of astrocytic production of and response to IL-6 by using transgenic mice deficient in astrocytic IL-6 (Ast-IL-6 KO) or in its receptor (Ast-IL-6R KO) in full C57Bl/6 genetic background. A major prosurvival effect of astrocytic IL-6 at early ages was clearly demonstrated. Robust effects were also evident in the control of activity and anxiety in the hole-board and elevated plus-maze, and in spatial learning in the Morris water-maze. The results also suggest an inhibitory role of IL-6 in the mechanism controlling the consolidation of hippocampus-dependent spatial learning. Less robust effects of astrocytic IL-6 system were also observed in despair behavior in the tail suspension test, and social behavior in the dominance and resident-intruder tests. The behavioral phenotype was highly dependent on age and/or sex in some cases. The phenotype of Ast-IL-6R KO mice mimicked only partially that of Ast-IL-6KO mice, which indicates both a role of astrocytes in behavior and the participation of other cells besides astrocytes. No evidences of altered function of the hypothalamic-pituitary-adrenal axis were observed. These results demonstrate that astrocytic IL-6 (acting at least partially in astrocytes) regulates normal behavior in mice.

A frontal dopamine system for reflective exploratory behavior

The COMT gene modulates dopamine levels in prefrontal cortex with Met allele carriers having lower COMT enzyme activity and, therefore, higher dopamine levels compared to Val/Val homozygotes. Concordantly, Val/Val homozygotes tend to perform worse and display increased (interpreted as inefficient) frontal activation in certain cognitive tasks. In a sample of 209 participants, we test the hypothesis that Met carriers will be advantaged in a decision-making task that demands sequencing exploratory and exploitive choices to minimize uncertainty about the reward structure in the environment. Previous work suggests that optimal performance depends on limited cognitive resources supported by prefrontal systems. If so, Met carriers should outperform Val/Val homozygotes, particularly under dual-task conditions that tax limited cognitive resources. In accord with these a priori predictions, Met carriers were more resilient in the face of cognitive load, continuing to explore in a sophisticated manner. We fit computational models that embody sophisticated reflective and simple reflexive strategies to further evaluate participants' exploration behavior. The Ideal Actor model reflectively updates beliefs and plans ahead, taking into account the information gained by each choice and making choices that maximize long-term payoffs. In contrast, the Naïve Reinforcement Learning (RL) model instantiates the reflexive account of choice, in which the values of actions are based only on the rewards experienced so far. Its beliefs are updated reflexively in response to observed changes in rewards. Converging with standard analyses, Met carriers were best characterized by the Ideal Actor model, whereas Val/Val homozygotes were best characterized by the Naive RL model, particularly under dual-task conditions.

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.

A computational model for exploratory activity of rats with different anxiety levels in elevated plus-maze

The elevated plus-maze is an apparatus widely used to study the level of anxiety in rodents. The maze is plus-shaped, with two enclosed arms and two open arms, and elevated 50cm from the floor. During a test, which usually lasts for 5min, the animal is initially put at the center and is free to move and explore the entire maze. The level of anxiety is measured by variables such as the percentage of time spent and the number of entries in the enclosed arms. High percentage of time spent at and number of entries in the enclosed arms indicate anxiety. Here we propose a computational model of rat behavior in the elevated plus-maze based on an artificial neural network trained by a genetic algorithm. The fitness function of the genetic algorithm is composed of reward (positive) and punishment (negative) terms, which are incremented as the computational agent (virtual rat) moves in the maze. The punishment term is modulated by a parameter that simulates the effects of different drugs. Unlike other computational models, the virtual rat is built independently of prior known experimental data. The exploratory behaviors generated by the model for different simulated pharmacological conditions are in good agreement with data from real rats.

Postoperative cognitive dysfunction: Involvement of neuroinflammation and neuronal functioning

Postoperative cognitive dysfunction (POCD) has been hypothesized to be mediated by surgery-induced inflammatory processes, which may influence neuronal functioning either directly or through modulation of intraneuronal pathways, such as the brain derived neurotrophic factor (BDNF) mediated pathway. To study the time course of post-surgical (neuro)inflammation, changes in the BDNF-pathway and POCD, we subjected 3months old male Wistar rats to abdominal surgery and implanted a jugular vein catheter for timed blood sampling. Cognition, affective behavior and markers for (neuro)inflammation, BDNF and neurogenesis were assessed at 1, 2 and 3weeks following surgery. Rats displayed changes in exploratory activity shortly after surgery, associated with postoperatively elevated IL-6 plasma levels. Spatial learning and memory were temporarily impaired in the first 2weeks following surgery, whereas non-spatial cognitive functions seemed unaffected. Analysis of brain tissue revealed increased neuroinflammation (IL-1B and microgliosis) 7days following surgery, decreased BDNF levels on postoperative day 14 and 21, and decreased neurogenesis until at least 21days following surgery. These findings indicate that in young adult rats only spatial learning and memory is affected by surgery, suggesting hippocampal dependent cognition is especially vulnerable to surgery-induced impairment. The observed differences in time course following surgery and relation to plasma IL-6 suggest cognitive dysfunction and mood changes comprise distinct features of postoperative behavioral impairment. The postoperative changes in neuroinflammation, BDNF and neurogenesis may represent aspects of the underlying mechanism for POCD. Future research should be aimed to elucidate how these players interact.

Contingent auditory feedback of arm movement facilitates reaching behavior in infancy

The purpose of this study was to investigate the influence of contingent auditory feedback on the development of infant reaching. Eleven full-term infants were observed biweekly from the age of 10 weeks to 16 weeks, and their arm kinematics were recorded. Auditory feedback that was contingent on arm kinematics was provided in the form of: (a) the mother's voice; and (b) musical tones. Results showed that providing auditory feedback (mother's voice or musical tones): (i) increased the amplitude of exploratory arm movements before the onset of reaching; and (ii) increased the number of reaches at the onset of reaching. These results show that infants are able to use contingent auditory feedback to explore the relevant possibilities for action that are subsequently shaped into goal-directed movements.

Are increases in COP variability observed when participants are provided explicit verbal cues prior to COM stabilization?

Previous research has shown that when the COM is stabilized without participant awareness, COP displacements increase. This finding suggests that postural sway under normal conditions may be exploratory and used as a means of acquiring sensory information. However, based on the theory that posture is controlled using internal models, it could be argued that increases in COP displacement reflect errors that arise as the central nervous system attempts to adapt the internal model used to control posture to the new conditions. The current study provided an explicit verbal cue to the participants indicating how and when COM stabilization would occur. Based on evidence suggesting that explicit verbal cues can reduce errors when the dynamics of the task are altered, we hypothesized that when participants were aware of COM stabilization, COP displacements would be reduced. However, we found that anterior-posterior COP displacements increased independent of cueing, suggesting that increases in COP displacements with locking were not the result of an attempt to adapt the internal model of postural control. The results provide further support for an exploratory role of postural sway.