Frontiers in Behavioral Neuroscience

Operant paradigms are powerful tools to quantify motivation and reward. Traditionally, operant conditioning research has been limited to food and drug reinforcers. Recent advances in commercially available operant equipment, however, allow for the quantification of social motivation. These operant assays are an improvement over commonly used social preference tasks, as they enable direct measurement of the effort and motivation driving social behavior. Based on a design by Venniro et al. (2020), the MedPC social operant boxes modify the traditional operant box setup for social interactions. The experimental rat can lever-press to raise a door for an interaction with a target rat behind a porous barrier. These social operant boxes have been widely adapted to test social behavior in adult and adolescent rodents and investigate how a range of conditions (e.g. stress, drug taking, etc.) affect social motivation. However, there is a gap in assessing maternal motivation for pups during the postpartum period, despite ample evidence that postpartum social behavior is highly relevant for offspring health outcomes. Here, we detail 3D-printed modifications to the standard Med PC social operant boxes to adapt the social target chamber to safely house neonatal pups. We have also developed testing protocols to assess motivation during the limited postpartum period. These data demonstrate that, with simple modifications to social operant chambers and testing protocols, the field can implement advanced behavioral approaches to directly assess maternal motivation.

Motivational deficit is a prevalent symptom across a wide range of neurodegenerative and neuropsychiatric disorders. Despite its clinical importance, first-line treatments for these disorders fail to effectively treat this symptom domain. In animal models, motivation is typically assessed in the context of extrinsic reward, where reward is delivered for completing an effortful action. However, many motivated behaviours occur in the absence of a tangible reward and are instead driven by intrinsic motivation. Previous work has shown that an extrinsic motivation task (effort for reward (EfR)) and an intrinsic motivation task (effort based forage (EBF) task) show opposing responses to a range of pharmacological manipulations. However, it is not clear whether intrinsic and extrinsic motivation dissociate in the context of endogenous behavioural variation. We therefore investigated whether these tasks were sensitive to behavioural variation across three different strains of mice (C57Bl/6JJRi, 129S2/SvPasOrlRj and BALB/cJRi) and whether strain profiles diverged across tasks. Here, we found that BALB/c mice showed the lowest levels of foraging in the EBF task, indicative of a low intrinsic motivational state but showed the highest levels of high effort responding in the EfR task, indicative of a high extrinsic motivational state. These differences were not driven by an anxiety-related phenotype and were therefore indicative of a motivation phenotype divergence across tasks. This work highlights the importance of moving away from considering motivation on a single axis, as findings can diverge depending on the nature of the motivational process. This has important implications for both phenotypic interpretation and the development of treatments targeting motivational dysfunction.

The rapidly increasing number of video tracking-based behavioral summary tools and methods raises the question as to the most suitable approaches for pharmacological fingerprinting in pre-clinical research. We have recently shown that social context has a strong effect on behavioral syntax in mice, further suggesting that treatment effects can be context dependent. Here, we aim to answer the question whether there is an optimal combination of context and behavioral summary method for effect detection and discrimination of different psychoactive substances in a controlled environment. To this end, we applied eight different treatment-dosage pairs (amphetamine 1.5,3,6 mg/kg; modafinil 5,10,50 mg/kg; seltorexant 3,10 mg/kg) and evaluated five different approaches to behavioral summary: parametric aggregation, unsupervised segmentation in Keypoint-MoSeq (KPMS) & Variational Animal Motion Encoding (VAME), and supervised segmentation in Simple Behavioral Analysis (SimBA) & A-SOiD, across two different contexts (Solitary & Social) in 314 recordings of freely moving mice in an open-field arena. Surprisingly, our results show no significant differences in performance across models and context. Across treatment effect detection to treatment-dose discrimination, all models showed performance significantly above chance that was insensitive to various data limitations and extensions. Overall, our study shows that under the tested conditions and treatments, the choice of a behavioral summary model does not meaningfully affect the description of treatment effects. Simple aggregate measures from tracking data and machine learning based behavioral summary approaches that are expensive, in terms of training data and computational resources, performed equally well. Our findings taken together with literature suggest that the fuller decomposition of complex behavior through unsupervised machine learning might be necessary for the description of large-scale datasets but does not necessarily align with the goals present in smaller-scale treatment discrimination tasks common in pre-clinical research.

RationaleAdolescence is a period of heightened vulnerability to nicotine reinforcement. While zebrafish are a valuable model for investigating drug reward, standard conditioned place preference (CPP) assays typically test subjects in isolation. In this highly social species, solitary testing may act as an environmental stressor that confounds behavioral readouts. ObjectivesThis study examined how social context during testing (isolated vs. grouped) affects experimental attrition, behavioral stability, and nicotine CPP expression in late juvenile zebrafish. MethodsZebrafish housed in groups of four were tested either individually (isolated) or in their housing groups (grouped) during daily 20-minute sessions. Following baseline preference assessments, subjects underwent six days of conditioning pairing their initially non-preferred compartment with fish water or nicotine (0.5, 1.6, or 5.0 {micro}mol/L). Place preference, locomotion, and thigmotaxis were assessed on a drug-free test day. ResultsIsolated testing reduced distance traveled, decreased swimming speed, and increased time spent near tank walls, indicating heightened anxiety-like behavior. Experimental attrition was significantly higher in isolated (38.9%) than grouped (2.5%) subjects. Grouped subjects developed significant place preference at 1.6 and 5.0 {micro} mol/L nicotine, whereas preference was not detectable in isolated subjects. ConclusionsSolitary testing acts as a stressor that increases experimental attrition and masks place preference. Conversely, testing in the presence of conspecifics stabilizes behavior and facilitates the detection of nicotine reward in late juvenile zebrafish.

Despite its strong link to neuropsychiatric conditions, frustration remains critically understudied in humans and animals alike. Therefore, there is an urgent need to develop tools to understand and therapeutically target frustration-related functions. Interestingly, humans and rats respond similarly during frustrative nonreward by increasing barpress durations. We previously validated barpress duration in rat operant tasks as a reliable measure of frustration-related behavior; however, it is wellknown that in addition to duration of responding, emotional states such as frustration alter other aspects of responding such as force of pressing. One-dimensional, static measures such as maximum force could miss rich information contained within operant data. Thus, the objective of this study is to apply machine learning (ML) to force/time profiles to discriminate frustration-related barpresses from non-frustration-related barpresses. Results showed an AUROC for FR1 (i.e., non-frustrated) vs. extinction (frustrated condition) for individual barpresses of 0.65 that improved to 0.84 with a chunk size of 10. The model generalized well to progressive ratio responding, a different kind of frustration procedure. We conclude that force/time profiling does provide utility beyond one dimensional measures of duration or force separately, meaning that we can indeed infer the internal state of frustration from behavior using ML techniques. Importantly, this project will also serve as proof-of-concept for applying ML to predict other internal states from barpress data.

Epilepsy affects approximately 30% of individuals with autism spectrum disorder (ASD). Consistent with these observations, while PRICKLE mutations are primarily linked with epilepsy, there is an enrichment of pathogenic DNA sequence variants in PRICKLE genes carried by individuals with ASD. Nonetheless, a connection between PRICKLE function and ASD warrants further investigation. Here, we show that a seizure-prone Drosophila prickle mutant (prickle-spiny-legs, or pksple) exhibits learning and memory deficits, increased pain sensitivity, both communication and social interaction difficulties, and restrictive repetitive grooming behaviors, all of which are strongly correlated with ASD, while a non-seizure prone prickle mutant (prickle-prickle, or pkpk) does not, thereby providing a direct genetic connection between epilepsy and ASD through prickle. Comparing headed versus headless pksple mutants, we also show that the excessive grooming requires higher level cognitive processing from the brain. Finally, both pksple and pkpk mutants exhibit circadian rhythm defects, another feature correlated with ASD, as well as distinct yet overlapping neurological anomalies in processes that include innate immune response, oxidative stress response, neuronal cell death, neurodegeneration, motor dysfunction and reduced lifespan, likely reflecting the unique isoform expression patterns observed in the developing CNS. Collectively, this study highlights the broadscale effects of PRICKLE mutations that extend beyond the primary clinical features of epilepsy to include several of the core features of ASD.

Huntingtons disease (HD) is a progressive neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin (HTT) gene. The disease is characterized by movement disorders, and it also presents with personality changes, including apathy and aggression, along with cognitive decline. While most animal models for HD have been validated for motor deficits, less is known about alterations in other behavioral functions. Here, we performed a longitudinal study to analyze the behavior of a knock-in mouse model of HD with a chimeric mouse/human exon 1 containing 140 CAG repeats inserted in the murine huntingtin gene. We specifically inquired about the onset of cognitive impairments in knock-in mice and whether changes in various behavioral functions such as locomotion, anxiety, and cognition correlate at the individual level. Our data indicate that female and male knock-in mice exhibit reductions in body weight, novelty-induced locomotion, and remote spatial memory retrieval. However, social behavior, working, and short-term memory remain unaffected. Within knock-in mice, lower open-field activity correlated with poorer remote memory performance. Moreover, CAG repeat length negatively correlated with locomotor activity and spatial memory, indicating that greater repeat expansion predicts more severe behavioral impairment. These findings identify early affective changes, followed by selective long-term memory and locomotor deficits, in knock-in mice, supporting this model as a useful platform for studying prodromal HD and repeat-length-dependent disease variability. HighlightsO_LICAG140 knock-in mice show early anxiety, later reduced locomotion and memory deficits C_LIO_LILong-term and remote memory are impaired while short-term and working memory are spared C_LIO_LILower locomotion at the age of 8 months correlates with poorer memory at 14 months of age in individual CAG140 knock-in mice C_LIO_LIGreater CAG repeat length predicts worse locomotion and memory C_LI

Perceived or volitional control over a stressor is a critical determinant of resilient versus susceptible behavioral phenotypes. Activation of the lateral habenula (LHb) is required for the behavioral changes or "learned helplessness" effects that follow inescapable, but not escapable, stress. However, the relevant LHb inputs that regulate its mediation of inescapable stress outcomes are not fully elucidated. We find that ventral tegmental area (VTA) glutamatergic axons in LHb are activated by aversive stimuli, and this activation was not altered by prior inescapable stress experience. Similarly, optogenetic activation of VTA glutamatergic axons in LHb resulted in c-Fos expression in LHb neurons that did not depend on a prior inescapable stress experience. Photoinhibition of VTA glutamatergic axons in LHb during each inescapable stress trial prevented social and nonsocial consequences of inescapable stress. We interpret these results such that VTA glutamatergic inputs to LHb report aversive stimuli to LHb, possibly related to current salient aversive experience without regard to prior stress history. Nevertheless, VTA glutamatergic input to the LHb plays an important role in regulating LHb-mediated social and nonsocial consequences of uncontrollable stress.

Risk for opioid use disorder (OUD) is substantially heritable, yet its genetic architecture remains only partly understood. This study examined oxycodone intake in two nearly isogenic rat strains, Wistar Kyoto More Immobile (WMI) and Less Immobile (WLI), and their reciprocal female F1 offspring. The parental strains differ in depression-like behavior and substance use vulnerability, with WMI rats consuming more oxycodone than WLI controls. Voluntary consumption was measured with an operant licking self-administration protocol that delivered 60 l drug per reward. Across four experimental stages, oxycodone concentrations increased from 0.025 to 0.1 mg/ml, and session durations increased from 1 to 4 hours. Female offspring showed a parent-of-origin effect. F1 females sired by WMI fathers (WLIxWMI) displayed accelerated escalation during the transition from 1-hour to 4-hour sessions in Stage 2 and consumed more oxycodone than reciprocal WMIxWLI females across expanded-access stages. This vulnerability was associated with increased licking during the drug-unavailable timeout period. In WMI and reciprocal WMIxWLI female, consumption was regulated by the drugs subjective value, as measured by lick microstructure, during Stages 1 and 2. This relationship was absent in WLIxWMI females during Stage 2. Together, these findings suggest that paternal WMI lineage is associated with a rapid transition to high oxycodone intake and cue-directed drug seeking, and identify a parent-of-origin effect that may contribute to female vulnerability to addiction.

In recent years, rodent touchscreen-based paradigms have gained popularity for their flexible task design, automated data collection and improved standardization. These devices minimize experimenter intervention and contribute to more replicable and reliable research. However, the high costs and proprietary hardware / software associated with commercially available systems present a financial barrier for smaller labs or researchers with limited resources. To address this issue, we developed "NC4Touch", an open-source scalable, modular rodent testing apparatus. It features three independent touchscreens and a feeding port for easy use in a wide array of tests comparable to those available with standard operant chambers, with the added benefit that visual stimuli can be highly customized. The system includes a user-friendly graphical interface that offers real-time control, task customization, video recording, and data management. We demonstrate its effectiveness in a visual discrimination task using both rats and mice. Several devices can be operated in parallel from the same computer and user interface, allowing high- throughput data collection. We provide detailed assembly instructions for the hardware and well- documented and easily-configurable software. We hope that the affordable open-source nature of NC4Touch will expand the scope of behavioral testing, allowing researchers to overcome traditional financial barriers and create a more collaborative community. Significance StatementTouchscreen-based testing is a powerful tool for assessing cognition in rodent models, however commercial systems remain cost-prohibitive for many researchers. NC4Touch is a rodent touchscreen apparatus that provides an open-source, customizable, and affordable alternative that enables high-throughput, cognitive testing in both mice and rats. By lowering financial barriers and promoting hackability, this system enables greater accessibility and collaboration in research.

Behavioral test batteries are increasingly used to characterize multiple functional domains in zebrafish, yet the potential impact of test sequence on behavioral outcomes remains poorly defined. Here, we systematically evaluated whether test order influences behavioral responses in a three-assay battery comprising the novel tank test (NTT), mirror-induced aggression (MIA), and social preference (SP) test. Adult zebrafish (Danio rerio) were exposed to all possible permutations of the three assays in a fully counterbalanced design, allowing assessment of order effects across locomotor, anxiety-like, aggression-related, and social behaviors. Test order produced modest and parameter-specific effects, primarily affecting locomotor activity in the NTT and social proximity in the SP assay. Time-course analysis revealed within-test behavioral dynamics, with limited evidence that test order modulates early adaptation or late engagement with the testing environment but does not alter overall temporal response profiles. Sex-dependent effects were assay-specific and most pronounced in the NTT, with no consistent sex differences observed in MIA or SP. To evaluate the global structure of behavioral variation, Principal Component Analysis (PCA) was performed across assays. Despite localized effects of test order, no clear multivariate separation between test sequences was observed, indicating that sequential testing does not produce distinct baseline phenotypes. Together, these findings support the robustness and reproducibility of multidomain behavioral batteries while highlighting the importance of standardized test-order reporting to improve cross-study comparability.

Social isolation is commonly used to model social stress and is a known risk factor for depression, with impacts on hippocampal function and postnatal neurogenesis. However, most studies focus on social isolation in juvenile mice isolation during adolescence, leaving the effects of prolonged adult isolation less understood. Post-transcriptional regulation of gene expression by microRNAs (miRNAs) plays a role in hippocampal function, and altered miRNA, as well as gene expression, has been reported in the hippocampus of mice exposed to social isolation. A single-nucleotide polymorphism in miR-30e in humans is associated with increased expression of the mature miRNA, impaired cognition, electroencephalogram waveform latency, depression, and schizophrenia. We investigated whether adult isolation in mice alters gene regulation via microRNAs, particularly miR-30e-5p, and affects hippocampal function. In adult BALB/c male mice, 10 weeks of isolation increased miR-30e-5p expression in the ventral hippocampus, reduced its target gene Neurod1, and impaired hippocampal-dependent cognition (object pattern separation), without clear anxiety- or depression-like behaviours. Isolated mice also showed a blunted response to acute stress. These findings suggest that adult social isolation affects hippocampal function through post-transcriptional gene regulation, highlighting a role for miR-30e-5p in neurogenesis and cognition in response to psychological stress.

Quantitative analysis of rodent behaviour is fundamental to neuroscience, preclinical drug discovery and neurotoxicology research. Although several commercial and open-source software packages are available for behavioural assessment, some are expensive, some require programming expertise, and some provide limited flexibility for user-defined experimental configurations. To address these limitations, we developed Robean, a freely available standalone software platform for automated rodent neurobehavioural analysis from both live camera feeds and pre-recorded videos. Robean provides an intuitive graphical user interface that enables users to design experimental arenas, define custom analysis zones, perform spatial calibration, and automatically track rodent movement without requiring programming knowledge. The software currently supports automated analysis of three widely used behavioural paradigms: the Morris Water Maze, Elevated Plus Maze, and Open Field Test. Robean extracts behavioural metrics including escape latency, path efficiency, platform crossings, target quadrant preference, thigmotaxis, locomotor activity, zone occupancy, arm entries, and centre exploration specific to behavioural tests. In addition, the software generates trajectory maps, occupancy heatmaps, comma-separated value (CSV) datasets, comprehensive PDF reports, and batch study summaries for multiple experimental sessions. Developed using open-source software technologies and distributed as a standalone freeware application, Robean provides an accessible and reproducible solution for behavioural neuroscience laboratories. Its modular architecture facilitates future integration of additional behavioural paradigms and analytical modules, making it a flexible platform for automated rodent behavioural assessment.

Post-Traumatic Stress Disorder (PTSD) commonly occurs alongside Traumatic Brain Injury (TBI), yet the chronic behavioral consequences of combined neurotrauma (i.e., PTSD and TBI) across the sexes remain unclear. Using a mouse model combining Single Prolonged Stress (SPS) as a model for PTSD and Controlled Cortical Impact (CCI) as a model for TBI, we assessed gait, anxiety-like behavior, and contextual fear learning and extinction at 2, 4, and 12-weeks post-injury. Combined neurotrauma produced early and persistent gait impairments in both sexes, delayed changes to anxiety-like behavior characterized by reduced avoidance of an anxiogenic environment, and long-lasting contextual fear recall deficits. Impaired learning was observed in males, where they demonstrated reduced fear acquisition and diminished extinction rates at later time points while females showed no deficits. Across testing and sex, peak deficits emerged at 4 weeks post-neurotrauma. Together, these findings define a sex- and time-dependent behavioral phenotype following combined neurotrauma and underscore the importance of modeling comorbidity to capture the temporal and neurobehavioral consequences of trauma exposure that more closely reflect clinical populations.

Early life adversity can produce persistent changes during development that increase vulnerability to neuropsychiatric disorders. Although disruptions in reward processing are widely recognized as a hallmark of these disorders, reward is not a single construct. Distinct forms of reward including social interaction and primary rewards such as food rely on overlapping but dissociable neural circuitry and may be differentially affected by adverse experiences. Here, we used a rodent model of neonatal predator odor exposure (POE) to determine how early life threat influences motivation for social and sucrose reward in adulthood using operant procedures. Neonatal POE reduced adult motivation for a social reinforcer during an operant social self-administration task, whereas motivation for a sucrose reinforcer was unchanged. However, we did find a significant difference in sucrose self-administration with POE females pressing more for sucrose than control females. These findings demonstrate that neonatal threat does not produce a generalized deficit in motivation but rather selectively alters motivation across distinct reward domains. Together, this work identifies social reward as a particularly vulnerable behavioral domain following early life threat and provides new insight into how adverse developmental experiences shape adult reward-related behavior.

We previously reported, using in-vivo fiber photometry, that operant responding reinforced by access to a peer (social self-administration) is associated with phasic dopamine increases in nucleus accumbens (NAc) core following lever insertion (reward-availability cue) and gradual increases preceding lever-pressing. Here, we sought to replicate these findings and determine whether dopamine signals (1) generalize to responding for high-carbohydrate palatable food, (2) show opposite patterns during negative reinforcement (shock avoidance/escape), and (3) depend on whether reinforcers are experienced alone or together. We trained rats (n=11; 6 females) to lever-press for access to a same-sex peer (15 s/trial) and palatable food (45-mg pellet/trial), followed by shock avoidance/escape (0.18-0.26 mA). After training, we expressed the dopamine sensor GRAB-DA2m and implanted optic fibers into NAc core. We measured dopamine activity during sessions with either one- or three-reinforcers. During social self-administration, dopamine activity showed phasic increases following lever insertion and gradual increases preceding lever-pressing; responses were moderately greater during sessions with all three reinforcers. Palatable food self-administration showed a similar pattern, but responses were approximately twofold greater during single-reinforcer sessions. During shock avoidance/escape, dopamine activity showed phasic decreases at warning onset, lever insertion, and shock onset; responses were also greater during single-reinforcer sessions. Results suggest that NAc core dopamine signaling distinguishes positive from negative reinforcement and is modulated by reinforcer availability. Compared with single-reinforcer sessions, dopamine responses during food self-administration and shock avoidance/escape were reduced during sessions with all three reinforcers, whereas responses during social self-administration modestly increased. Significance statementNucleus accumbens (NAc) dopamine is critical for processing the valence of positive reinforcers, whereas its role in negative reinforcement is less well understood. Here, we extended our prior work on operant social self-administration to determine whether these findings generalize to food reinforcement, show the opposite pattern during operant negative reinforcement (shock avoidance/escape), and depend on whether reinforcers are experienced alone or together. Results suggest that NAc core dopamine activity differentiates positive and negative reinforcement and is modulated by the presence of other available reinforcers. Specifically, dopamine responses during food self-administration and shock avoidance/escape were reduced when all three reinforcers were available together compared with when each reinforcer was experienced alone, whereas responses during social self-administration showed the opposite pattern.

20% of Americans are at risk for environmental circadian rhythm disruptions (CRD) due to shift work, leading to substantial negative health outcomes. However, females are especially affected with greater vulnerability for substance use (SU) and adverse outcomes associated with pregnancy, including for offspring at birth and later in life. In mice, prenatal CRD (pCRD) recapitulates these risks, but it is unknown whether pCRD affects SU in mature offspring. To investigate this, C57BL/6J dams were disrupted by reversing the light/dark cycle during gestation. Following pCRD, reward- (cocaine conditioned place preference, intravenous self-administration) and mood-related behaviors (open field, elevated plus maze, light/dark box, forced swim) were measured in adult offspring. Adult female offspring of dams exposed to CRD developed an anhedonic-like phenotype with decreased food self-administration, cocaine intake and reinforcing properties of cocaine. Opposingly, pCRD male offspring showed a SU-like phenotype with increased cocaine preference, higher order food self-administration and cocaine reinforcement. Interestingly, these divergent behavioral outcomes were not specific to reward. While female pCRD mice showed increased anxiety-like behavior, pCRD males showed decreased anxiety/increased risk-taking behavior, as well as decreased immobility in the forced swim test. Rhythms in corticosterone were also sex-specifically affected by pCRD. These results suggest that pCRD may predispose individuals to distinct psychiatric disorders based on sex with mood disorders developing in females and SU disorders developing in males. By better understanding how disrupted rhythms during pregnancy affect behavior in adulthood, we can develop novel therapeutic approaches for SU and mood disorders in adults.

Although female rats are typically less aggressive than male rats, lactating females will vigorously defend their nests and pups against an intruder. Much attention has been directed at the consequences of this aggression on the intruder and less on the consequences for the mother and her subsequent interactions with her pups. Here, we exposed resident Sprague-Dawley dams to the resident-intruder paradigm twice daily for five consecutive days, beginning when the dam's (RES) pups were 7 days old, to assess social stress effects on maternal behavior and neurobiology. Controls were dams that had time-matched (TMC) separation from their pups but were not exposed to intruders, and naive moms which were never separated nor exposed to an intruder (CTL). We assessed the dam's subsequent behavior and interactions with her pups on Day 1 and Day 5, and Fos expression after Day 5 in select regions of the prefrontal cortex, amygdala, hypothalamus and periaqueductal gray of the midbrain. In separate cohorts, after pups were weaned, the dams underwent restraint stress and plasma corticosterone assayed. PCA analysis of the dam's behaviors identified three components: normal self-focused behaviors; nurturing behaviors and rough non-nurturing behaviors. Relative to CTL, RES dams exhibited more disrupted behaviors towards their pups, including, rough transport, stepping on pups, and flinging/tossing pups around the cage. In contrast, TMC Dams showed some, but fewer changes relative to CTL, suggesting that separation from pups alone does not account for all disrupted behavior in RES dams. The bulk of these behavioral effects occurred in the first 5-10 min after reunion with the pups and were seen on both the first and fifth day of testing. Of the brain regions examined, the prefrontal cortex was activated by both the defeat/intruder stress (RES) and separation stress (TMC), whereas the dorsal PAG was activated specifically by the defeat/intruder stress. The medial and basolateral amygdala exhibited differential neuronal activity between the RES defeat/intruder-exposed dams and the other two groups. The RES moms exhibited an insufficient adrenocortical response to acute restraint stress. The results suggest that amygdala-dPAG activity is important for dissociating disrupted maternal care in RES (due to defense of the nest against an intruder) from simple pup separation, both of which activate the mPFC. The experience of repeatedly defending the nest may induce subsequent disruptions in HPA responses. The amygdala-dPAG pathway may regulate aspects of stress and emotional regulation exhibited by mothers who defend their offspring against intruders.

Rationale: Early life stress (ELS) is acknowledged to underlie cognitive and emotional abnormalities linked to stress-related mood disorders. ELS can lead to persistent biases in how uncertain feedback is processed to affect the flexibility of decision-making. Objectives: (1) To investigate the effects of ELS on the flexibility of rats trained on a serial probabilistic reversal learning (PRL) task involving spurious positive and negative feedback. (2) To elucidate the involvement of the stress hormone corticosterone and the noradrenergic and serotonergic systems in modulating how ELS affects PRL. Methods: Male and female rats were intermittently separated from maternal care on postnatal days five to nineteen, inclusively. As adults, the same rats were trained on a deterministic reversal learning task involving certain rewarded or non-rewarded outcomes followed by a PRL task where correct and incorrect responses were rewarded on 80% and 20% of trials, respectively. Dose-dependent effects of the beta-blocker, propranolol, selective serotonin reuptake inhibitor, citalopram and corticosterone were subsequently determined. Results: ELS resulted in an increased responsivity to feedback, specifically in males making more win-stay responses following a reward, that was associated with an increased punishment learning rate. In both control and MS rats, propranolol increased feedback sensitivity, but delayed updating following a rule switch. In contrast, neither citalopram nor corticosterone significantly affected reversal learning. Conclusions: ELS is sufficient to cause persistent changes in how feedback is processed by male rats on a reversal learning task. Activation of beta-adrenergic receptors may be necessary for updating learned associations during decision-making involving uncertain feedback.

Humans make emotional facial expressions and have a cardiac response when they catch themselves in a mistake or receive feedback about task performance. We tested whether rats exhibit similar visceral responses in the context of metacognition. We assessed heart rate variability (HRV) and machine learning-detected facial expressions as female and male rats detected and stopped in-progress mistakes and received post-choice rewards or error cues. HRV increased during internally detected mistakes, as well as in response to external error cues for both sexes. Errors were associated with an HRV response when parasympathetic tone was higher, while rewards were associated with an HRV response when sympathetic tone was higher. We observed sex-specific effects of cardiac interoception on cognitive control over real-time action correction, in that low parasympathetic tone was associated with reduced ability to stop in-progress mistakes exclusively in females. Rats made facial expressions during mistake detection and in response to task feedback. Outcome-related facial expressions were valence-specific, in that the facial expression after error feedback was delayed relative to the post-reward facial expression. Our results suggest that rats have a visceral experience during metacognitive monitoring.