Frontiers in Behavioral Neuroscience

The midsession reversal (MSR) task is frequently used to study behavioral flexibility and decision strategies in animals. In a typical version of the task, subjects complete 80 trials in which they choose between two simultaneously presented stimuli, S1 and S2. During the first 40 trials, responses to S1 are reinforced, whereas responses to S2 are not. The contingencies then reverse without warning: From trial 41 to 80, only responses to S2 are reinforced. In birds, performance in this task is often characterized by anticipatory and perseverative errors around the reversal point, suggesting a reliance on elapsed time since the session began. In contrast, rats tested in operant conditioning chambers typically show near-optimal performance with few errors, a pattern often interpreted as evidence that rats rely primarily on local reinforcement cues rather than temporal information. The present study investigated whether rats exclusively rely on local cues in the MSR task or whether temporal information also contributes to the decision process. Two groups of rats were trained with different intertrial intervals (ITIs; 5 s or 10 s) while the reversal point remained fixed at Trial 41. During acquisition, both groups diplayed similar learning rates and near-optimal steady-state performance with minimal anticipatory or perseverative errors. However, when the ITI was manipulated in probe sessions, systematic shifts in switching behavior emerged. Rats adjusted their choices according to the temporal midpoint experienced during training rather than the nominal trial number of the reversal. These results suggest that rats rely on a mixed strategy that integrates local reinforcement cues with global timing information. Temporal control may therefore be present even when it is not expressed during standard training conditions.

Neuropsychiatric (depression, schizophrenia, etc.) and neurological disorders (Alzheimers disease, AD, Parkinsons disease) are characterized by disruptions in cognition including social interaction and recognition. Developing tools for the assessment of social behaviour in mouse models and its relevance is essential to further advance our understanding of social impairments in these diseases. In the Agora maze for rodents, stranger mice confined into cubicles around the perimeter of the open square mirror the agora (marketplace) in ancient cities. Up to 5 social interaction partners are presented and can be freely selected for interaction (exposure). In the discrimination phase one novel mouse (SNew) is presented while 4 familiar partners remain. Interaction time is recorded via video observation. In Exp 1, we validated the test with different strains of wild-type male mice (C57BL/6J, Balb/c, NMRI) that were able to readily identify SNew and spent significantly more time in zones adjacent to their cubicle; only NMRI mice did not prefer SNew. Exp. 2 explored 5xFAD Alzheimer mice and showed normal exploration and discrimination when aged 6 and 8 months old. Repeat of the experiment in a second cohort confirmed robustness of this phenotype, but also reproducibility of the behavioural paradigm. The Agora task allows semi-automated evaluation of preference for social novelty in a more complex paradigm by expanding the number of social interaction partners from 2 (three-chamber test) to 5 (or more), while still avoiding physical approaches and aggressive episodes. Thus, Agora provides a more physiological behavioural paradigm which is highly robust and reproducible. HighlightsO_LIMore comprehensive behavioural test bed for social recognition C_LIO_LIMale wild-type mice can identify a stranger mouse amongst 5 social interaction partners C_LIO_LINo deficit in amyloid-based Alzheimer model 5xFAD aged 6-8 months. C_LIO_LIRepeat of experiments returned highly robust and reproducible results. C_LI

Quantitative phenotyping is essential to studies of animal behavior, enabling systematic analysis of variation arising from natural diversity or experimental manipulation. High-throughput behavioral assays that can simultaneously test multiple animals support sufficiently powered studies of behavioral variation, but accurate tracking of each animal is critical. Furthermore, behavioral tasks and experimental arenas span a wide range of complexity, from the reaction of a single larval zebrafish to an acoustic stimulus to associative conditioning in cue-rich environments. Here, we developed and validated StrIPETrack (Structural similarity-based Image Processing for Estimation and Tracking), a Python-based, modular animal tracking software designed for flexible region-of-interest (ROI) definitions and extensibility across assays. We show that StrIPETrack measures activity comparably to our previous LabVIEW-based zebrafish tracking software and detects similar behavioral differences between wild-type clutches. In addition, StrIPETrack accurately captures behavior in a complex arena: the Y-maze. Our approach for analyzing Y-maze navigation yields an expanded set of metrics beyond turn count and direction, revealing more subtle behavioral variation. Overall, this versatile software can be applied to monitor the activity of multiple animals in parallel in both simple high-throughput and more complex assays, and can be readily adapted to new paradigms. SummaryOur open-source tracking software provides rich behavioral phenotyping of animals in many behavioral tasks. The flexible ROI design and live tracking makes the software adaptable to diverse paradigms.

BackgroundThe three-chamber test (3CT) is widely used to assess social behaviour in mice, based on the assumption that time spent near a conspecific reflects motivation for social contact. However, the design of the task constrains interpretation, as behaviour may reflect exploration, novelty seeking, or territorial investigation rather than affiliative social motivation. In addition, key biological factors such as sex differences and social hierarchy are often overlooked. AimsWe hypothesised that the 3CT overestimates sociability and used a direct-interaction phase to investigate motivation for affiliative social contact. We also integrated social status to determine if this modulated behavioural patterns and interacted with sex. MethodsAdult male and female C57BL/6 mice (n = 32) were tested in a standard 3CT, followed by removal of the cage barrier to permit direct contact. Behavioural parameters were quantified, and social status was determined using the tube test. ResultsMales exhibited higher social interest index scores than females. Once the barrier was removed, both sexes displayed a negative direct sociability index, indicating greater environmental exploration than social engagement. Correlation analysis revealed no association between indirect and direct measures. Sex differences emerged primarily among submissive mice, with submissive males showing greater social investigation than submissive females. ConclusionThese findings suggest that standard 3CT indices reflect exploratory rather than affiliative social motivation. The modified paradigm incorporating direct interaction provides a more realistic assessment of social behaviour and challenges assumptions about intrinsic sociability in mice.

Attention-deficit/hyperactivity disorder (ADHD) is a developmental psychiatric disorder associated with a complex interplay of genetic and environmental risk factors. We have shown embryonic dorsal forebrain loss in mice of fibroblast growth factor receptor 2 (Fgfr2), which has a critical role in normal brain development, results in ADHD-relevant phenotypes: increased locomotion and sociability, and impaired working memory postnatally. How such genetic vulnerabilities interact with environmental exposures to translationally model human ADHD risk remains unclear. Here, we pair the embryonic hGFAP-cre Fgfr2 conditional knockout (Fgfr2 cKO) mouse model with prenatal repetitive restraint stress, modeling an environmental factor associated with ADHD risk, to assess adult offspring behaviors and dopamine transporter (DAT) levels. Offspring of prenatally stressed, Fgfr2 cKO mice show increased locomotion (80% compared to non-stressed, Fgfr2 cKO animals). Prenatal stress led to a trend increase in impulsivity and trend decrease in working memory but did not affect sociability. There were no interactions with Fgfr2 cKO observed in these behaviors. Neurobiologically, prenatal stress led to a trend decrease in medial frontal cortex DAT, but these changes did not correlate with behavior. Taken together, our findings implicate prenatal stress as a potential contributor to gene-environment interactions for ADHD risk, supporting its use in translational animal models of childhood psychiatric disorders.

Physical activity offers myriad benefits to health and well-being, in humans and other animals as well. In rodents, voluntary wheel running can attenuate the effects of both physical and social stressors on rodent social behavior. Whether wheel running affects rodent social behaviors per se remains less well understood. We conducted the current study to test whether home cage access to running wheels impacts the social behaviors of adult, group-housed C57BL/6J female mice during same-sex interactions with novel females. Group-housed females were either given continuous home cage running wheel access or a standard paper hut starting at weaning, and as adults, social behaviors were measured during interactions with novel females. In two cohorts, we found that 5 weeks of running wheel access during adolescence reduced the time that subject females spent investigating a novel female and also tended to reduce total ultrasonic vocalizations produced during interactions. These effects were not reversed by a 2-week period of running wheel removal but were recapitulated in a different cohort by 2 weeks of running wheel access in adulthood. Unexpectedly, we found that these effects on female social behavior were not due to wheel running per se, because females raised from weaning with immobile running wheels also showed low rates of social behaviors during same-sex interactions in adulthood. Overall, we find that the presence of a running wheel in the home cage has an enduring inhibitory influence on female social behavior during same-sex interactions, a finding that has implications for the design of studies that include same-sex interactions between female mice.

Sex differences in responses to chronic stress are implicated in the higher prevalence of major depression and PTSD in females. Evidence of sex differences in endocannabinoid (eCB) physiology suggests that eCB signaling contributes to sexual disparities in fear conditioning and extinction. In adolescent male Sprague-Dawley rats, exposure to chronic-mild-unpredictable stress (CMS) resulted in enhanced trace-fear conditioning that was reversed by CB1 activation (Reich et al, 2013). In the present study, we assessed the effects of CMS and CB1 activation on hippocampal-dependent trace and contextual fear conditioning in adolescent female Sprague-Dawley rats. CMS exposure enhanced trace freezing behavior during memory recall compared to non-stress controls. This effect was not observed in contextually conditioned females. The CB1 receptor agonist, ACEA (0.1 mg/kg), administered prior to trace memory recall, but not prior to acquisition, significantly decreased freezing in both stress and non-stress females. ACEA significantly reduced baseline freezing behavior during trace memory recall in both stress and non-stress rats, however ACEA either 1) did not affect or 2) impaired short and long-term extinction in stress and non-stress females. In contextually conditioned females, ACEA decreased freezing during memory recall, although the effect was more robust in stress rats. ACEA impaired long-term contextual extinction in stress females while facilitating this in non-stress controls. However, ACEA had no effect or impaired short-term contextual extinction in both stress and non-stress groups. The results demonstrate that CMS enhances hippocampal-dependent episodic fear memories but has limited effects on contextual fear conditioning in female rats. These findings have implications in the use of medical cannabinoid treatment of disorders such as PTSD, as well as recreational cannabis use in adolescent/young adult females.

Flexible reward-seeking relies upon an organisms integration of expectations about environmental cues with knowledge of actions that produce rewards, which is captured by pavlovian instrumental transfer (PIT). Although widely used to study motivation across species, rodent PIT paradigms differ from human tasks in lacking an active baseline for comparison. Here we adapted the full PIT paradigm to include a non-rewarded cue (CSO) as an active control with the aim of improving the translational relevance of the procedure. Despite robust pavlovian and instrumental learning, neither male nor female rats expressed outcome-specific PIT when the active baseline was present. The absence of PIT persisted even after instrumental extinction training prior to the test, though cue-driven magazine approaches remained elevated. Data obtained under these conditions may reflect protocol-dependent modulation by the amount of training, or strain-specific differences in motivational influence. Replicated across male and female cohorts, they identify boundary conditions where PIT appears less robust. This methodological adaptation advances the translational alignment between animal and human PIT paradigms and informs future investigations into the mechanisms of cue-motivated behaviour.

BackgroundLong-term home-cage monitoring is essential to quantify spontaneous locomotor and social behaviors in group-housed mice, but analysis of high-density RFID tracking data remains a barrier to reproducibility. New methodsWe developed IntelliProfiler 2.0, a fully R-based pipeline tailored to the eeeHive 2D floor-mounted RFID array. The workflow performs data import from text logs, preprocessing, coordinate reconstruction, missing-value handling, feature extraction, statistical testing, and visualization in a single environment. Behavioral metrics include travel distance, close contact ratio (CCR), and a newly implemented inter-individual distance metric. ResultsIn four-day recordings of group-housed C57BL/6J mice (8 males and 8 females), IntelliProfiler 2.0 captured circadian phase-dependent locomotion and proximity patterns and reproduced sex-dependent differences consistent with prior analyses while incorporating updated hardware specifications. Radar-chart summaries enabled intuitive comparison of multidimensional behavioral profiles and inter-individual variability across light/dark phases. Comparison with existing methodsCompared with IntelliProfiler 1.0 and multi-tool workflows, IntelliProfiler 2.0 consolidates analysis into a single, script-based R pipeline, reducing operational complexity and improving reproducibility. The updated implementation supports recent manufacturer-driven changes, including antenna renumbering and multi-USB data export. ConclusionsIntelliProfiler 2.0 provides a reproducible, extensible framework for high-throughput behavioral phenotyping of group-housed mice and is scalable across hardware configurations, including simplified single-board recordings. HighlightsO_LIEnd-to-end R pipeline for eeeHive 2D floor-based RFID tracking analysis C_LIO_LIStandardized setup with comprehensive manuals and protocols C_LIO_LIInter-individual distance metric to quantify group spatial structure C_LIO_LICircadian- and sex-dependent behavioral profiling in group-housed mice C_LIO_LIRadar-charts summarize multidimensional behavioral profiles and variability C_LI

Behavioral dysfunction is a common characteristic of many mental health disorders. While the causes of these disorders vary, aberrant behaviors may arise from alterations in transcriptional regulation already during early neural development. Because transcription factors (TFs) often belong to families of closely related members, disruption of a single TF may indirectly influence the functionality of other family members. Consequently, mutations in TFs within the same family may lead to overlapping, yet distinct, phenotypes. This feature of TF function has important implications for understanding behavioral phenotypes, but detailed analyses across a single TF family are still lacking. In this study, we present a comprehensive behavioral analysis of adult zebrafish harboring mutations in individual members of the TALE and Hox TF families, that are essential for nervous system development. Using a battery of validated behavioral assays, we uncover elevated stress responses among all TF mutant lines, as well as TF-specific dysregulation in coping strategies, social interaction, learning/memory, and endurance and locomotion. The shared behavioral abnormalities across mutants suggests TF family members converge on core developmental pathways for stress-related behavioral regulation, while mutation-specific phenotypes indicate unique roles for individual TFs in fine-tuning neural function. Our findings provide a systematic behavioral characterization of TALE and Hox mutants in a vertebrate model and provide a framework for understanding how genetic variation within TF families may differentially contribute to vulnerability for mental health disorders.

Traumatic stress can cause long-lasting changes in cognition and affect, sometimes leading to diagnoses such as post-traumatic stress disorder (PTSD). The stress-enhanced fear learning (SEFL) model recapitulates understudied components of PTSD, such as stress-induced sensitization of fear learning. The SEFL procedure entails exposing mice to footshock stress followed later by fear conditioning in a different context. When tested later for recall of fear conditioning, previously stressed mice exhibit enhanced freezing compared to non-stressed controls. Studies have shown that dorsal and ventral dentate gyrus (DG) generates neural ensemble representations of contextual fear, such that fear recall involves reactivation of a sparse set of "engram cells" that were active during fear memory acquisition. How stress affects these hippocampal ensemble representations is unknown. We used SEFL and activity-dependent neuronal tagging with FosTRAP2 mice to investigate effects of stress on fear memory ensembles in rostral and caudal hippocampal DG. FosTRAP2/Ai6 mice received footshock stress or equivalent context exposure without shock in Context A on day 1. Five days later, mice received 1-shock conditioning in Context B and immediately received an injection of 4-OHT (55mg/kg) to tag fear acquisition neurons with the zsGreen reporter. One day later, mice were tested for fear recall in Context B and were perfused 90 minutes after testing. Confirming prior studies, prior stress potentiated 1-shock conditioning in Context B, with stressed mice displaying higher freezing in the Context B test session than non-stressed mice. At the level of neural activity, results showed stress had no effect on the number of zsGreen+ fear ensemble cells or the number of cfos+ recall-activated cells in rostral or caudal DG. However, stress increased reactivation (percentage of zsGreen+ cells expressing cfos) in the caudal but not rostral DG. The results suggest stress potentiates later fear learning by enhancing fear representations in caudal hippocampus, a region of the hippocampus specialized for integrating emotional and motivational valence into memory.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a prevalent neurodevelopmental condition characterized by persistent deficits in working memory (WM) and executive control. Dysregulation of the Cyclin-dependent kinase 5 (Cdk5)/p35 signaling pathway has been implicated in ADHD pathophysiology due to its impact on neuronal connectivity and dopamine regulation. Using p35 knockout (p35KO) mice--a validated model exhibiting ADHD-like phenotypes--we investigated sex-specific WM performance, task-related neuronal activation patterns, and responses to acute treatment with methylphenidate (MPH) or fluoxetine (FLX), administered alone or in combination. Under basal conditions, p35KO mice of both sexes exhibited significant WM impairment in the Y-maze test compared with wild type (WT) counterparts, whereas recognition memory remained intact. Analysis of neuronal activation (c-Fos-IR) 90 min after testing revealed region-, sex-, and genotype-dependent alterations. Overall, p35KO animals of both sexes showed reduced c-Fos-IR expression in prefrontal cortical regions, while exhibiting increased c-Fos-IR in hippocampal regions. Acute MPH or FLX treatment improved WM in p35KO males, but this benefit was not observed following combined treatment (MPH+FLX). In contrast, p35KO females showed no WM improvement with any treatment. Notably, WT females exhibited a pronounced decline in WM after exposure to MPH, FLX, or their combination, indicating sex-specific pharmacological sensitivity in healthy animals. These findings support an important role of Cdk5/p35 signaling in the functional engagement of prefrontal and hippocampal networks and demonstrate that pharmacological responses in this ADHD model are strongly influenced by sex and neurobiological background, highlighting the importance of incorporating sex as a biological variable in preclinical and translational ADHD research. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=123 SRC="FIGDIR/small/696253v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@12b4330org.highwire.dtl.DTLVardef@14826c3org.highwire.dtl.DTLVardef@1e8f3d8org.highwire.dtl.DTLVardef@e108a2_HPS_FORMAT_FIGEXP M_FIG C_FIG

Background and aimsPerseverative behaviours are commonly assessed using operant paradigms in which rodents work for drugs or food under physiological deprivation, limiting translational relevance to some behavioural addictions. Here we validated an operant paradigm in which the acquired behaviour is driven neither by physiological needs nor hedonic responses. MethodsMice were trained to lever-press for green light. Exp.1 used a within-subjects design to examine lever discrimination and whether responding could be "satiated" by light preexposure. Exp.2 examined instrumental contingency using a between-subjects design, with light delivery equated between contingent and non-contingent groups. Exp.3 replaced green light with dim red light producing less retinal photoreceptor excitation but comparable heat to assess non-photic cues. Exp.4 examined whether green light could affect food seeking different motivational states. ResultsIn Exp.1, green light supported lever discrimination. Among high responders, the satiation effect was modest (<15% reduction) and did not deter lever pressing. In Exp.2, instrumental contingency promoted response acquisition whereas random light delivery did not. In Exp.3, dim red light failed to sustain behaviour, producing [~]50% response decrement. In Exp.4, light potentiated food seeking under ad libitum feeding. Discussion and conclusionsResponse-contingent light serves as a reward to establish operant responding, which cannot be explained by alerting effects or thermal cues. Our study bridges the gap between animal models and findings from humans that coloured light may exacerbate smartphone use and that light therapy may reshape reward circuits in individuals with Internet gaming disorder symptoms [Li et al. (2026) Advanced Science 13:e14044].

BackgroundPavlovian responding is a core component of behavior and can be measured via Pavlovian-instrumental transfer (PIT), where Pavlovian responses bias instrumental actions. Standard single-lever PIT paradigms, which assess responses using a single-choice option, cannot dissociate the contribution of model-free versus model-based reinforcement learning. While indirect evidence suggests a role for model-free responding in single-lever PIT, the contribution of model-based strategies is unclear. It also remains unknown whether internal cognitive states, such as mind wandering, impair specifically model-based but not model-free PIT, as is theoretically expected. MethodsWe developed a novel, trial-by-trial two-stage PIT paradigm designed to computationally dissociate model-free and model-based Pavlovian responding by leveraging probabilistic state transitions and trial-wise outcome predictions. After each two-stage Pavlovian learning trial, participants performed a single-lever PIT trial as well as a query trial of explicit value judgment. Detailed task instructions were provided to support potential model-based strategies. Computational modeling was used to quantify individual learning strategies. We assessed mind-wandering questionnaires and thought probes. ResultsAnalysis of query and PIT trials revealed trial-by-trial updating of outcome expectations based on probabilistic task structure, consistent with model-based Pavlovian responding. Behavioral responses during PIT were best explained by a computational model-based reinforcement learning model. In contrast, we found little evidence for model-free Pavlovian responding. Higher levels of mind wandering were associated with reduced model-based control but did not impact model-free indices. ConclusionWe introduce a novel single-lever PIT paradigm that enables fine-grained dissociation of model-free versus model-based Pavlovian response systems. Our findings provide evidence that single-lever PIT can operate through model-based mechanisms, challenging the assumption that single-lever PIT is predominantly model-free. Our findings also indicate that internal attentional states selectively modulate model-based PIT. Given the involvement of Pavlovian responding in numerous psychiatric conditions, our paradigm offers new avenues for understanding maladaptive behavior. Author SummaryOur daily actions are often influenced by cues like the smell of food or the sound of phone notifications that signal potential rewards or losses. These Pavlovian cues can shape our instrumental behavior even though their outcomes do not depend on what we do - a process known as Pavlovian-instrumental transfer (PIT). Here we study the computational learning mechanisms that underlie such PIT effects. While it is often assumed that Pavlovian responding follows simple, automatic rules without a cognitive model of cue consequences (i.e., model-free), evidence also shows a role for cognitive anticipations in Pavlovian responding (i.e., model-based). In this study, we extend this evidence by showing that PIT responding can be driven by flexible model-based learning. We designed a task to test whether participants use model-free versus model-based strategies to guide PIT, providing detailed task instructions. Using reinforcement learning models, we found that most participants used model-based learning when forming cue-outcome associations. Importantly, peoples attention mattered: when they were more distracted and doing mind wandering, they relied less on model-based strategies. Our findings suggest that Pavlovian learning is complex, flexible, and influenced by internal mental states, opening new windows to understand decision-making problems in mental health conditions like addiction.

Stressors are commonly used in rats to induce models of anxiety or depression. The effectiveness of these stressors is often evaluated using specific behavioural tests. In a previous meta-analysis of chronic variable stress (CVS) procedures, we predicted that longer and more intensive stress procedures would result in larger effect sizes in behavioural tests. However, we found that the duration or intensity of CVS procedures did not correlate strongly with the magnitude of the effect sizes reported in behaviouraltests. In that study, we were concerned that the large and unexplained diversity in CVS procedure design, both in terms of duration and the types of stressors used, made it challenging to detect the factors that were influencing effect size. In an effort to address this, we explore here the use of a much simpler stress procedure - chronic restraint stress (CRS) - to study the relationship between the duration of CRS procedures and the effect sizes obtained in subsequent behavioural tests. We searched PubMed for articles using CRS procedures with rats, systematically documented the total duration of restraint, and carried out a meta-analysis of the effect sizes obtained in four behavioural tests: the forced swim test (FST), the sucrose preference test (SPT), the elevated plus maze (EPM) and the open field test (OFT). We found that chronic restraint stress increased immobility in the FST, decreased sucrose preference in the SPT, decreased time spent in the open arms of the EPM but had no effect on time spent in the centre of the OFT. However, the effect sizes in all behavioural tests, except the SPT, were not moderated by the duration of the CRS procedure, indicating that longer CRS procedures are associated with larger effect sizes in the SPT but not in the FST or EPM.

BackgroundEarly-life adversity can alter emotional and social development and increase vulnerability to later life stress. We investigated how early adverse experiences (EAE) and later adverse experiences (LAE) shape adult emotional contagion (EC) responses in female and male rats. MethodsEAE was induced using the limited bedding and nesting model during the first postnatal week. LAE was induced via footshocks during adolescence. In adulthood, male and female rats underwent an EC test in which observers witnessed a conspecific receiving footshocks. ResultsAdolescence-footshock exposed observers showed cingulate cortex-associated increased immobility, proximity, and attention toward distressed conspecifics during adulthood, compared to adult-exposed and sham animals, both in male and female animals. While EAE did alter maternal care, pup stress physiology, and pup weight, we found evidence that it did not alter immobility during EC. However, female demonstrators paired with EAE observers showed increased immobility, linked to a reduced rate and lower frequency of the observers 50-kHz vocalizations. Mediation analysis revealed that a shift toward lower-frequency 50-kHz vocalizations specifically mediated this effect, suggesting a sex-specific pathway by which early adversity shapes social behavior. ConclusionsEarly and adolescent adversity influenced distinct aspects of emotional contagion: EAE mediated an observer-to-demonstrator emotional transfer during EC, while LAE impacted a demonstrator-to-observer transfer, with no evidence of additive effects. Our results highlight developmentally specific and sex-dependent mechanisms by which early and later adversity alter social-affective responses in adulthood.

An increasing number of epidemiological and experimental studies have demonstrated a bidirectional relationship between mood disorders and the circadian system, with disrupted circadian rhythms contributing to depressive states, and their restoration playing a key role in antidepressants effects. In this context, we sought to examine whether key molecular targets of antidepressants exhibit diurnal regulatory patterns. Naive adult male and female C57BL/6 mice were euthanized at 3-hour intervals beginning at Zeitgeber Time 0 (ZT0), and hippocampal (HC) and medial prefrontal cortex (mPFC) tissues were collected for RT-qPCR and western blot analyses. We observed statistically significant diurnal rhythmicity in all analyzed transcripts (cFos, Arc, Nr4a1, Dusp1, Dusp5, and Dusp6) in both HC and mPFC samples, with peak expression occurring during the dark (active) phase (ZT15-18). Phosphorylation levels of TrkBY816 (tropomyosin-related kinase) and GSK3{beta}S9 (glycogen synthase kinase 3{beta}) also showed periodic rhythmicity, peaking during the light (inactive) phase. Levels of p-ERK2T185/Y187 (extracellular-signal regulated kinase) did not display rhythmicity, but peaked during the light phase in the HC, especially in males. Collectively, these findings demonstrate that antidepressant targets are subject to diurnal regulation, highlighting the importance of integrating circadian biology and time-of-day as relevant variables in the development of translationally relevant antidepressant research. HighlightsO_LIKey molecular targets of antidepressants exhibit diurnal regulation in adult mice C_LIO_LIDiurnal patterns were conserved across targets, sexes, and brain regions (HC&PFC) C_LIO_LIcFos, Arc, Nr4a1, Dusp1,5,6 mRNAs display peak expression during the dark phase C_LIO_LITrkBY816 and GSK3{beta}S9 phosphorylation peak during the light (inactive) phase C_LIO_LIAntidepressant mechanisms may be linked with circadian and sleep-wake dynamics C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/716906v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1e65e60org.highwire.dtl.DTLVardef@13e302corg.highwire.dtl.DTLVardef@1ccc25forg.highwire.dtl.DTLVardef@1ed10d3_HPS_FORMAT_FIGEXP M_FIG C_FIG

By relying on the observation of others experiences, humans learn about threat while avoiding harmful experiences. Yet, previous neuroscience research has focused on observational threats that are predictable. While the neurobiological distinction between temporally predictable (cued) and unpredictable (contextual) threats has been well-characterized in firsthand learning. In this study, we developed a novel observational paradigm in which participants learned from predictable (P) and unpredictable (U) observational threats, as well as a no-threat (N) condition and encountered the same conditions during an expression phase based on the NPU paradigm to investigate how the brain encodes predictable and unpredictable threat cues observed in others. Participants in Experiment 1 (n=20, male and female) and Experiment 2 (n=23, male and female) successfully learned threat contingencies, showing heightened threat expectations for predictable cues and unpredictable contexts. This converged with neural (fMRI, Experiment 2) responses in the anterior insula during the expression phase. Reflecting the dynamic process of learning, the amygdala responded to predictable threat cues with a linear decrease across trials. Interestingly, we found that responses to others pain was enhanced within the amygdala, insula and hippocampus, when participant could learn to predict threats, as compared to unpredictable conditions. Our findings suggest that humans learn to resolve temporal uncertainty, relying solely on observation, which thereby lays a foundation to the concept of fear and anxiety in social groups.

Developing scientific reading skills is critical for undergraduate STEM students due to scientific literatures unique formatting and use of specialized jargon. Generative AI tools such as ChatGPT offer students the ability to ask questions about what they are reading interactively. Previously, we reported the development of a ChatGPT-assisted reading guide that combined structured, active reading strategies with using ChatGPT to clarify unfamiliar words and concepts in real time. In the initial study, undergraduates found the use of the ChatGPT-assisted reading guide helpful in their understanding of an abstract and introduction of a journal article. Here, the ChatGPT-assisted reading guide was used in a journal club assignment for an undergraduate chemistry course. ChatGPT transcripts were analyzed for common types of interactions, and students were surveyed about their experience. Overall, students reported that using the ChatGPT-assisted reading guide was helpful in understanding the article and helped them have more productive class discussions. However, some students also expressed skepticism about using AI tools, citing concerns about accuracy of AI-generated information and the effect of using AI on their own learning.

Prairie voles (Microtus ochrogaster) are highly social rodents that have become a valuable animal model for studying social attachment, pair bonding, parental care, and the neurobiological mechanisms underlying social behavior. In recent years, due in part to the publication of the prairie vole genome and deeper mechanistic understanding of their social behavior, prairie voles have become a more popular research model, especially for translational research. However, generating reliable and reproducible findings requires effective colony management, including thoughtful breeding strategies, consistent husbandry practices, and clear documentation. In this paper, we describe the demographic history of and husbandry techniques employed in our prairie vole breeding colony at UC Davis from 2004 to 2020. Well-organized and transparent colony management allows for the preservation of informative behavioral traits in prairie voles and strengthens the impact of the prairie vole model across behavioral and biomedical science.