Neurobiology of Stress

Ambiguity represents a form of uncertainty in which outcome probabilities cannot be explicitly learned, making decisions dependent on emotional states and cognitive biases. Early-life stress (ELS) increases the risk of adverse mental and physical health outcomes and alters affective processing and learning. ELS may thus affect how ambiguous information is processed, which may depend on interactions with adulthood stress (AS) and mechanistically on bioenergetic mechanisms mediated by top-down cognitive control systems within the prefrontal cortex (PFC). The present study investigated the effects of AS in rats exposed to early maternal separation (MS), a rodent model of ELS, on a task assessing cognitive bias, together with putatively accompanying alterations in PFC mitochondrial function. Cognitive bias was assessed using an ambiguous cue task (ACT) in MS and non-separated control rats tested at baseline and following repeated unpredictable mild stress during adulthood. MS did not affect baseline cognitive bias but increased response latencies. Following AS, control animals showed a significant negative shift in cognitive bias, whereas MS animals were resistant to this shift. MS was also associated with greater PFC mitochondrial respiratory capacity and uncoupling of oxidative phosphorylation following AS. These findings suggest that ELS is associated with a recalibrated phenotype that buffers against the affective consequences of later stress. Enhanced PFC mitochondrial bioenergetics may underlie this resilience, highlighting the importance of developmental context in shaping affective-cognitive responses to stress.

Chronic stress alters striatal functions involved in motivation, action selection, and behavioral adaptation, yet cell-type-associated transcriptional organization in the dorsal striatum remains unclear. We used RNAscope-guided GeoMx spatial transcriptomics to compare D1 and D2 neuronal compartments in matched dorsal striatal regions after chronic restraint stress (CRS). CRS engaged both populations and produced comparable numbers of differentially expressed genes. Gene set enrichment analysis revealed partially overlapping CRS-associated pathway attenuation in D1 and D2 neurons, indicating stress-responsive transcriptional organization in both populations. However, D2 responses showed more coherent convergence around receptor-trafficking and synaptic signaling programs, including AMPA receptor trafficking and EPHB-mediated signaling. Moreover, under the same threshold-defined DEG criteria, CRS-downregulated D2 genes resolved into synapse-centered functional annotation categories, including glutamatergic synapse, postsynaptic organization, and dendritic spine, whereas D1 gene sets did not show a comparable pattern. These findings provide a framework for comparing stress-associated D1/D2 transcriptional organization in the dorsal striatum. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/737112v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@a57a73org.highwire.dtl.DTLVardef@a2cf8org.highwire.dtl.DTLVardef@e6ea0org.highwire.dtl.DTLVardef@180f997_HPS_FORMAT_FIGEXP M_FIG C_FIG

The medial habenula (MHb) is an epithalamic structure involved in aversive processing and emotional regulation, notable for its marked cellular heterogeneity and high astrocyte density. This cellular composition suggests that astrocytes may play an important role in MHb structure and plasticity, potentially contributing to the regulation of emotional states. The aim of this study is to characterize sex-dependent astrocytic morphology in the MHb and determine how it is modulated by peripheral alterations and direct central manipulations. A high-fat diet (HFD) was used as a model of metabolic stress, and systemic lipopolysaccharide (LPS) administration was used to induce a peripheral inflammatory challenge. At the central level, a chemogenetic approach using Gi-DREADDs under the GFAP promoter allowed selective modulation of astrocytic intracellular signaling independently of peripheral influences. Preliminary results indicate sex-dependent morphological differences in MHb astrocytes across all these experimental conditions, supporting the idea that MHb astrocytes are sensitive to both peripheral and central disturbances and may represent a key cellular substrate linking body-brain interactions with emotional regulation.

An appropriate stress response is essential for properly responding to, coping with, and subsequently recovering from disturbing environmental stimuli. However, how the brain dynamically encodes the scalability of stress responses remains poorly understood. Here, we found that, GABAergic neurons in the arcuate nucleus (Arc, denoted as ArcGABA neurons) send direct inputs to corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVH, denoted as PVHCRH neurons), the primary regulators of the hypothalamic-pituitary-adrenal (HPA) axis. Although PVHCRH neurons exhibited time-locked activation in response to various environmental stressors, both GABA release onto PVHCRH neurons and the activity of PVHCRH-projecting ArcGABA neurons were selectively reduced during exposure to prolonged, high-intensity stressors, but not following exposure to transient, low-intensity stressors. Notably, GABA release onto PVHCRH neurons was positively correlated with PVHCRH-projecting ArcGABA neuron activity, yet anticorrelated with PVHCRH neuronal activity in response to the same prolonged, high-intensity stressors. Selective silencing of PVHCRH-projecting ArcGABA neurons was sufficient to elevate HPA axis activity and stress levels, phenocopying the effect of direct of PVHCRH neuron activation. Conversely, selective activation of PVHCRH-projecting ArcGABA neurons reduced both HPA axis activity and stress levels, this effect was completely abolished by concurrent excitation of PVHCRH neurons. Molecular identity screening further revealed that these PVHCRH-projecting ArcGABA neurons are not subsets expressing agouti-related peptide (AgRP) and tyrosine hydroxylase (TH) markers. Collectively, these findings indicate that the non-AgRP/TH ArcGABA[->]PVHCRH neurocircuit serves as a critical neural substrate that directly encodes the scalability of stress responses to environmental stressors by modulating inhibitory GABA release in a stimulus intensity-dependent manner.

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.

Cortisol, our stress hormone, exerts widespread influence on neural activity. However, its influence on the aperiodic component of the electroencephalography power spectrum remains to be investigated. Given individual differences in the capacity to cope with stress and adversity, it also remains unclear whether trait resilience moderates this relationship. Hence, the present study examined whether individual differences in trait resilience moderates the association between resting cortisol and aperiodic activity. Participants (N=145) completed various self-report questionnaires (e.g., trait resilience). Electroencephalography was recorded over a 20-minute baseline period, followed by salivary cortisol collection. The results revealed a significant moderating effect of trait resilience in the occipital scalp region. Specifically, higher cortisol concentration was associated with flatter 1/f slopes amongst individuals with low trait resilience, whereas this association was reversed amongst those with high trait resilience. Overall, our findings highlight the role of individual differences in trait resilience in shaping hypothalamic-pituitary-adrenal axis-related neural dynamics.

Objective: Polygenic risk scores (PRS) for posttraumatic stress disorder (PTSD) often account for a low amount of variance. Ancestry-related differences in PRS scale and variance limit cross-group comparisons. This methodological challenge further complicates gene-by-environment (GxE) analyses, given that socioenvironmental exposures are inequitably distributed across ethnoracial groups. We constructed an ancestry-calibrated polygenic risk score (AC-PRS) for PTSD in the largest longitudinal study of trauma survivors to date and investigated GxE interactions. Method: Recent trauma survivors (N=1,801) provided a blood specimen for genotyping. Six PTSD trajectories were previously identified from PTSD Checklist for DSM-5 (PCL-5) scores at 2-weeks, 8-weeks, 3-months, and 6-months post-trauma. Greenspace (normalized difference vegetation index [NDVI) and socioeconomic disadvantage (area deprivation index [ADI]) were derived from residential addresses. Logistic regressions examined interactions between newly developed AC-PRS and neighborhood factors on trajectories after adjusting for sociodemographic and trauma-related covariates. Secondary linear models considered GxE interactions on 6-month PCL-5 scores. Results: AC-PRS performed well across ethnoracial groups, explaining significant variability in PTSD trajectories (R2=.053). ADI moderated the association between AC-PRS and the likelihood of assignment in a high nonremitting trajectory of PTSD symptoms and severity of symptoms at 6-months (ps < .05). There were no NDVI x AC-PRS interactions in any models. Conclusions: AC-PRS captures genetic risk for PTSD in admixed trauma survivors, demonstrating good discrimination between nonremitting and resilient courses of PTSD. However, neighborhood disadvantage may modify utility of PRS for PTSD, warranting careful consideration when applying these scores across contexts.

Early life stress (ELS), modeled in rodents through neonatal maternal separation (NMS), induces lasting behavioral and molecular alterations including pain hypersensitivity, anxiety-like behaviors, and cognitive deficits. While NMS disrupts the oxytocinergic system, the specific contribution of oxytocin receptor (OTR) dysfunction during critical neurodevelopmental periods remains unclear. Here, we investigated whether neonatal OTR blockade alone could recapitulate key features of the NMS phenotype. Control rats received daily injections of the selective OTR antagonist d(CH2)5-Tyr(Me)-[Orn8]-vasotocin (dOVT) during postnatal days 2-12, matching the NMS period. At adulthood, behavioral assessments revealed that control+dOVT animals exhibited mechanical and cold thermal hypersensitivity similar to NMS rats, though hot thermal sensitivity was unaffected. Anxiety-like behaviors observed in NMS animals were not reproduced by dOVT treatment. Notably, sex-specific spatial memory deficits emerged: male NMS and female control+dOVT rats showed impaired object location recognition, while females and males in their respective opposite groups remained unaffected. Molecular analyses of spinal cord tissue revealed significant downregulation of GAD65, BDNF, and CD11b in control+dOVT animals. Chloride cotransporters NKCC1 and KCC2 exhibited sexual dimorphism with opposite changes in NMS males versus females and different responses to dOVT. These expressions yet converged on an elevated NKCC1/KCC2 ratio in both sexes, indicating compromised chloride homeostasis despite sex-divergent molecular pathways. These findings demonstrate that developmental OTR dysfunction likely contributes to nociceptive and cognitive consequences of ELS, while anxiety-like phenotypes probably involve additional mechanisms. This work highlights OTR as a critical mediator of neurodevelopmental programming and a potential therapeutic target for mitigating ELS-related disorders.

Adrenal chromaffin cells are key effectors of the sympathoadrenal response and play a central role in the organisms adaptation to environmental and physiological challenges. While cholinergic and pituitary adenylate cyclase-activating polypeptide (PACAP)-dependent mechanisms have long been recognized as major regulators of catecholamine secretion, increasing evidence indicates that connexin-mediated gap junctional communication provides an additional and highly dynamic level of control. Whether early-life experience modifies the adult capacity of chromaffin-cell networks to undergo stress-induced connexin remodeling remains unclear. Here, we examined adrenal medullary connexin expression in adult rats exposed to neonatal maternal separation (MS; 3 h daily, postnatal days 2-15) and later challenged with an 8-day unpredictable mild stress (UMS) protocol. Under basal adult conditions, MS did not produce an overt change in adrenal medullary Cx36 or Cx43 immunoreactivity relative to animal-facility-reared controls. In contrast, UMS increased connexin immunoreactivity in the adrenal medulla, and this response was amplified in animals with a history of MS. MS+UMS animals also displayed enhanced corticosterone responses to acute restraint stress. These findings suggest that neonatal MS does not impose a constitutively altered adult chromaffin-cell phenotype, but instead primes the future stress responsiveness of adrenal medullary connexin remodeling. We propose that chromaffin-cell gap junctions represent a substrate sensitive to stress history, through which developmental experience may influence sympathoadrenal and endocrine adaptation in adulthood.

Stress during critical developmental periods causes lasting neurobiological alterations. Rodent models like neonatal maternal separation (NMS) induce cognitive alterations, particularly spatial memory deficits. Oxytocin (OT) system has been suggested to underlie these consequences, as it is critical for neurodevelopment. This neuropeptide also promotes maternal nurturing, prevents neuroinflammation and displays anxiolytic properties. This study hypothesized that early postnatal OT administration could prevent NMS-induced memory alterations in adult rats. Sprague-Dawley rat pups (both sexes, n=8-12/group) underwent NMS with concomitant intraperitoneal OT injections. At adulthood, novel object recognition and object location tasks were performed. Further investigation was conducted through ex vivo electrophysiological recordings of functional plasticity at Schaffer collateral-CA1 synapses (male, n=7-12/group), alongside RT-qPCR of synaptic, GABAergic, neuro-inflammatory, and oxytocin receptor markers in dorsal CA1 (male, n=4-6/group). NMS induced male-specific spatial memory impairment without affecting recognition memory. Early OT completely prevented spatial memory deficits in NMS males. Electrophysiological recordings revealed that NMS suppressed CA1 long-term potentiation (LTP), and neonatal OT restored it. NMS induced transcript overexpression of neuro-inflammatory markers, GABAergic markers, and synaptic proteins in dorsal CA1. OT treatment normalized or reduced these mRNA expressions, consistent with restoration of CA1 synaptic function. Early postnatal OT prevents NMS-induced spatial memory deficits and hippocampal LTP impairments in male rats, which is associated with normalized or reduced neuro-inflammatory and GABAergic transcript expressions. These findings establish exogenous oxytocin administration during a critical neonatal window as sufficient to prevent male-specific hippocampal dysfunction and cognitive deficits induced by early-life stress, identifying the oxytocinergic system as a promising target for early neuroprotective interventions.

Early-life adversity durably alters neural development through complex mother-offspring interactions whose underlying mechanisms remain poorly understood. We investigated how neonatal maternal separation (NMS) affects the large repertoire of maternal behaviors and subsequently influences spinal nociceptive circuit development and pain responses in rat offspring. Rat dams underwent NMS from postnatal day 2 (P2) to P12, 3h/day, and maternal behaviors were assessed before and after the separation period. These behaviors were compared to those of control (non-separated) dams. Offspring spinal cord and dorsal root ganglia were analyzed at P14 and P24 for several neurotrophic, glutamatergic, and GABAergic gene expression patterns. Offspring nociceptive sensitivity was also assessed at P24. NMS induced increased maternal behaviors (including longer arched-back nursing, higher nest occupancy, and better pup retrieval efficiency), alongside reduced self-care behaviors. These behavioral adaptations were correlated with spinal gene reprogramming in offspring, characterized by a biphasic developmental pattern. At P14, we observed elevated neurotrophic signaling alongside increased GABAergic and glutamatergic markers. By P24, neurotrophic factors decreased while compensatory changes emerged, yet persistent excitatory-inhibitory imbalances remained evident. Parallel to these results, NMS rats also showed mechanical and thermal hot hypersensitivity at P24. These findings reveal that despite apparent maternal behavioral compensation following NMS, offspring exhibit neurotrophic-driven developmental dysregulation resulting in persistent spinal circuit alterations. The disconnect between maternal behavioral normalization and sustained molecular changes suggests that early separation stress triggers enduring neurobiological cascades independent of ongoing maternal care quantity, with long-term consequences for sensory processing and pain sensitivity.

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.

Neurobiological mechanisms underlying child maltreatment perpetration remain poorly understood, and the role of immune dysregulation has rarely been examined. Here, we tested whether peripheral inflammatory signatures are linked to brain structural alterations in mothers who have perpetrated maltreatment, and whether such alterations mediate this link to perpetration. In this cross-sectional study integrating structural MRI and inflammatory proteomics, 16 mothers with histories of maltreatment perpetration and 145 age-matched control mothers underwent brain imaging; a subgroup (n = 52; 11 maltreatment, 41 control) also completed plasma proteomic profiling using the Olink Target 96 Inflammation panel. Whole-brain voxel-based morphometry revealed significantly reduced gray matter volume (GMV) in the right middle/inferior temporal gyri, a region implicated in social cognition and contextual interpretation, in the maltreatment group. Proteomic analysis identified 16 inflammation-related proteins differentially expressed between groups; among these, nine were significantly associated with GMV in this temporal region. Lower GMV was associated with higher levels of pro-inflammatory proteins (CCL20, IL-17C) and with lower levels of immune-regulatory and metabolic proteins (CXCL1, CXCL6, SIRT2, STAMBP, MCP-2, MCP-4, 4E-BP1). Mediation analyses revealed that both protein sets were indirectly associated with perpetration through this regional GMV, with opposing patterns of direct association. These findings suggest that peripheral immune imbalance, characterized by elevated inflammatory signaling and diminished immune-regulatory capacity, is linked to structural vulnerability in a temporal cortical region involved in social cognition, specifically in perpetrating mothers. This neuroimmune pathway may contribute to maladaptive interpretation of child signals during caregiving and represents a potential target for biomarker-informed preventive intervention.

BackgroundRepeated stress is a risk factor for developing motivational deficits which are common across a variety of disease states including depression and are particularly resistant to treatment with conventional pharmacotherapies. Amotivation is multifaceted and can be caused by impairments in value learning, reward anticipation, and cost-benefit decision-making. Importantly, not all individuals who experience chronic stress develop motivational symptoms, suggesting there may be neurobiological signatures of resilience. MethodsWe developed a novel head-restrained effortful reinforcement task in which anticipatory and consummatory behavior can be tracked. Chronic non-discriminatory social defeat stress combined with behavioral analysis and spatially resolved RNA sequencing were used to determine the transcriptional signatures of stress in the anterior cingulate cortex of mice with varying levels of motivational impairment as well as unstressed controls. ResultsWhile stress led to a general impairment in effortful reward seeking, animals differed in the extent of behavioral deficit, with increased susceptibility marked by a unique set of differentially expressed genes within the anterior cingulate cortex (ACC). By leveraging the spatial component of our data, we were further able to identify altered interactions from inhibitory neurons and astrocytes to excitatory pyramidal cells, which correlated with intact or impaired motivated responding following stress exposure. ConclusionsChronic psychosocial stress results in divergent effects on motivated behavior and distinct ACC transcriptional signatures that are concentrated in excitatory pyramidal neurons. Cell interaction analysis implicates enhanced inhibitory neuropeptide signaling and reduced astrocytic contact signaling as upstream markers of motivational resilience and point toward ACC hyperexcitability as a targetable feature of stress susceptibility.

Background: Childhood trauma exposure (TE) may heighten negative emotional responses, overwhelm cognitive control, and increase risk for anxiety disorders. Cognitive control is facilitated by glutamatergic (Glu) excitatory neurotransmission within the dorsal anterior cingulate cortex (dACC). Dynamic changes in dACC Glu levels were investigated using 1H functional magnetic resonance spectroscopy (1H fMRS) to assess the impact of negative emotional processing on neural mechanisms supporting cognitive control in TE-youth. Methods: Fifty adolescents were categorized into two TE-Groups: Higher (Mtrauma=6{+/-}1events) and Lower (Mtrauma=3{+/-}1events). 1H fMRS from the dACC was acquired during an inhibitory motor control task requiring tapping responses to stimuli under two Response Modes, NonSelective (100% response) and Selective (80% response, 20% inhibition), executed with two Stimuli Conditions, Squares (no emotion) and Faces (emotion). Glu modulation (relative to basal levels) was tested across TE-Group, Stimuli Condition, and their interaction. Within each Stimuli Condition, Glu modulation was tested across Response Modes by TE-Group. Results: We observed a 2-way interaction of TE-Group x Stimuli Condition ({chi}2=4.66, p=0.031). Post-hoc tests revealed significantly lower Glu modulation in Higher TE vs Lower TE (p=.023) during Faces but not Squares. This Glu modulation did not differ across Response Modes. Within the Higher TE-Group, Glu was significantly reduced during Faces compared to Squares (p<.001). Basal dACC Glu levels did not differ between groups. Conclusions: TE-Group differences in adolescent dACC Glu modulation were observed during cognitive control performed with emotional, but not non-emotional, stimuli, highlighting the value of 1H fMRS for detecting trauma-related differences in task-related excitatory neurochemical dynamics.

Post-traumatic Stress Disorder (PTSD) is a debilitating psychiatric condition caused by severe trauma exposure and characterized by ongoing dysregulation of fear processing, hyperarousal, and amygdala activation, but with limited effective treatments. Recent large-scale genome-wide association studies (GWAS) of PTSD have identified the transcription factor FOXP2 as a highly-significant, top putative risk gene. Both fine-mapping of the PTSD GWAS with amygdala-specific expression quantitative trait loci (eQTL) data, and transcriptome-wide association analyses, show that altered expression of FOXP2 is associated with increased PTSD risk. In vertebrates, FOXP2 mRNA is most densely expressed in the intercalated cells (ITCs) of the amygdala. ITC neurons receive excitatory input from external regulatory and sensory brain regions, as well as the basolateral amygdala, and send inhibitory projections to the central amygdala, which regulates downstream fear responses. While ITCs are critical for conditioned fear acquisition and extinction, the role of the FOXP2 gene in modulating fear-related behaviors remains unknown. Here, we used complementary bioinformatic, molecular, circuit, behavioral, and electrophysiological approaches to characterize the function of mouse (Foxp2) and human (FOXP2) orthologs in amygdala-mediated fear learning. To assess Foxp2 function in vivo, we first used shRNA-mediated knockdown (KD) of Foxp2 in ITC neurons of adult mice. Targeted Foxp2 KD robustly and significantly reduced freezing (threat/fear expression) during and after auditory fear conditioning. Whole-cell recordings from individual ITC neurons revealed that Foxp2 KD increased their intrinsic membrane excitability and action potential frequency, consistent with hypothesized enhanced inhibitory output to the central amygdala and thus reduced fear expression. This hyperexcitability was associated with reduced potassium channel conductance. Bulk RNA sequencing (RNA-seq) of mouse amygdala after ITC Foxp2 KD confirmed decreased potassium channel transcription and revealed broader Foxp2-dependent regulation of multiple genes implicated in fear learning, including Wnt, Crh (which encodes corticotropin-releasing hormone), and neurokinin signaling pathways. Consistent with these findings, bulk RNA-seq of medial amygdala postmortem tissue from humans with PTSD versus neurotypical controls showed decreased potassium channel transcription in samples with low FOXP2 expression. Downstream transcriptional changes following Foxp2 KD in the mouse amygdala also showed marked enrichment of genes identified in PTSD risk loci from the largest PTSD GWAS to date. Specifically, downregulated genes were enriched for mouse orthologs of Tier 1 PTSD GWAS risk genes. This enrichment appears to reflect subcortical Foxp2 signaling within the amygdala, driven predominantly by decreased expression of genes lacking promoter-anchored chromatin loops. This finding suggests that Foxp2 may directly bind regulatory elements of multiple top PTSD risk genes, acting as a key regulatory node for fear-related pathways in the amygdala. Collectively, our findings establish FOXP2 as a central transcriptional regulator of fear-related gene networks in the amygdala and potential regulatory hub for PTSD genetic risk.

The medial prefrontal cortex (mPFC) plays a significant role in modulating the threat response, particularly in ambiguous circumstances. The mPFC performs this role through its connectivity with multiple brain regions, including the amygdala, long regarded as the central hub for threat responses. However, the roles of specific prefrontal projections to the amygdala in contextual threat discrimination are not yet fully understood, particularly regarding more complex learning tasks and when disentangling the functionally distinct prelimbic (PL) subunit of the mPFC. Here, we challenged mice with a contextual differential threat conditioning (DTC) learning task in which subjects were repeatedly exposed to one context predictive of a foot shock (CS+) and to a similar yet distinct context that was not (CS-). While control mice showed a similar threat response in both contexts immediately after threat conditioning, within a few days of contextual exposures, controls acquire threat discrimination and freeze less to CS- than to CS+ during late DTC. However, we found that inducing localized hypofunction of neuroplasticity in PL neurons projecting to the basolateral amygdala (BLA) impairs performance on DTC. This finding identifies the specific population of neurons in PL cortices as a critical site for learning to discriminate threat.

Background Prenatal cannabidiol (CBD) consumption is increasing, driven by a perception of safety relative to delta-9-tetrahydrocannabinol (THC). However, the neurodevelopmental risks of gestational CBD remain largely uncharacterized. Methods Using a sex-disaggregated framework, we investigated adult (P100-140) mouse offspring following in utero exposure (GD5-18; 3 mg/kg) to THC or CBD. Behavioral strategies were evaluated through risk-assessment and repetitive behavior tasks, coupled with targeted electrophysiological mapping of medial prefrontal cortex Layer 5 neurons, the primary hub for approach-avoidance arbitration. Results We found that increased repetitive behavior was a universal feature of prenatal cannabinoids exposure. Alterations in risk appraisal emerged uniquely in CBD-exposed females and appeared dissociated from classical anxiety metrics. At the circuit level, THC and CBD were linked to an absence of endocannabinoid long-term depression (eCB-LTD). In males, CBD exposure coincided with a bidirectional plasticity collapse characterized by functional saturation, elevated AMPA/NMDA ratios, and slowed NMDAR activation kinetics. This ceiling effect may represent a top-down constraint on the prefrontal output circuit, potentially limiting the synaptic flexibility typically associated with adaptive behavioral transitions. In contrast, females exhibited compound-specific reorganizations of E/I balance. CBD-exposed females displayed a scaled-up architecture that preserved net E/I balance, whereas THC was associated with a pro-excitatory phenotype through the collapse of inhibitory control. Conclusions Despite a shared loss of eCB-LTD, distinct synaptic remodeling might underlie divergent alterations in risk assessment and behavioral flexibility. This sex-specific circuit rewiring provides a neurobiological framework for the long-term behavioral risks associated with gestational cannabinoid exposure.

Stress involves coordinated central and peripheral processes that unfold dynamically and can be assessed through brain, autonomic, endocrine, and subjective measures. Centrally, acute stress has been linked to altered functional connectivity, particularly in the salience (SN), frontoparietal networks (FPN), and default mode networks (DMN). Here, we used cortical gradients to characterize stress-related reconfiguration in macroscale functional space and assessed their relation to peripheral stress measures. We performed secondary analyses on data from 67 young males completing the Trier Social Stress Test or a control task with resting-state fMRI before and after, concurrent peripheral (autonomic, endocrine) and subjective measures. To assess region- and network-specific changes in functional organization, we derived eccentricity and within- and between-network dispersion for the first three cortical gradients. Acute stress was associated with selective gradient reconfigurations in the right ventral prefrontal cortex and left insula and with increased SN-DMN and SN-FPN dispersion, indicating DMN and FPN decoupling from the SN. Although no associations with peripheral or subjective stress measures survived multiple-comparison correction, nominal effects suggested partly distinct links of saliva cortisol with local gradient changes and HRV with network-level reconfiguration. Together, these findings show that acute stress selectively reconfigures macroscale cortical organization.

Traumatic brain injury (TBI) is one of the leading causes of emergency room visits in children under 10. Children are potentially more vulnerable to the adverse effects of TBI, given that their brains are still developing at the time of injury. Indeed, early life TBI has been linked to cognitive, social, and mood-related impairments later in life. The neuroimmune system has been implicated in adult TBI mechanisms and plays numerous key roles in brain development, making it an interesting candidate for linking pediatric TBI and prolonged behavioral alterations. Here we establish a rat model of mild pediatric TBI to investigate the relationship between early life TBI, acute responses of neuroimmune cells, and chronic behavioral dysregulation. At postnatal day 15, which is roughly equivalent to toddler age, male and female rat pups received a TBI via lateral fluid percussion injury. At 3 days post injury, TBI increased microglia and astrocyte coverage locally in the Perilesional Cortex but not in more distant corticolimbic regions. However, the hippocampus and prefrontal cortex did exhibit increased expression of the phagocytic marker CD68 in microglia, suggesting widespread glial activation even in the absence of gross coverage change. TBI also impacted mast cells, early-response innate immune cells, increasing their number and degranulation in multiple regions. In the juvenile and early adult periods, TBI impaired cognitive function, reduced sociability, and increased avoidance, with no change in anxiety-like behavior. Later in adulthood, TBI continued to impact cognitive behavior, increasing risky decision-making and impairing optimization months after injury. Together, these results suggest that pediatric TBI causes lasting cognitive and social dysregulation, possibly via acute neuroimmune alterations following injury at a critical period of brain development.