Stress, memory and the amygdala

Associations between triglyceride glucose index-related obesity indices and anxiety: Insights from the National Health and Nutrition Examination Survey 2007-2012

BACKGROUND

The triglyceride glucose index (TyG), along with its associated obesity indices, including TyG-body mass index (TyG-BMI), TyG-waist-to-height ratio (TyG-WHtR), TyG-waist circumference (TyG-WC), and TyG-weight-adjusted-waist index (TyG-WWI), have become valuable tools for evaluating insulin resistance in metabolic diseases. Few researches explored their links with anxiety.

METHODS

This observational study leveraged data from the National Health and Nutrition Examination Survey (2007-2012), analyzing 6726 participants to investigate the correlations between TyG-related indices and anxiety using multivariable logistic regression, subgroup analysis, and curve fitting.

RESULTS

After adjusting for confounders, significant positive correlations were identified between TyG, TyG-WWI, and anxious days [0.792 (0.262, 1.322); 0.033 (0.003, 0.063)]. These findings were reinforced when TyG-related indices were categorized into quartiles. Positive associations were further observed between TyG and anxiety state [1.243 (1.076, 1.437)], which was consistent across quartile groupings. Subgroup analyses revealed that racial stratification significantly influenced the relationship between TyG, TyG-BMI, TyG-WHtR, TyG-WC, TyG-WWI and anxious days. Gender stratification significantly influenced the relationship between TyG and anxiety state. Linear associations were established between TyG and anxious days, anxiety state with regression coefficients of 0.873 and 1.254 respectively. Non-linear relationships and threshold effects were detected, with inflection points at 187.731, 3.040, 725.288, and 104.011 (for TyG-BMI, TyG-WHtR, TyG-WC, TyG-WWI with anxious days) and 188.677, 3.059, 730.251, and 103.869 (for TyG-BMI, TyG-WHtR, TyG-WC, TyG-WWI with anxiety state).

CONCLUSIONS

These results enhance our understanding of relationships between TyG-related indices and anxiety, providing valuable insights for the prevention and management of obesity and anxiety.

Divergent amygdala function in proposed brain-first and body-first Parkinson's disease: a resting-state functional magnetic resonance imaging study

BACKGROUND

The newly proposed α-Synuclein Origin and Connectome (SOC) Model classifies Parkinson's disease (PD) patients into brain-first and body-first subtypes. In brain-first patients, α-synuclein may originate in the amygdala of one cerebral hemisphere and disseminate ipsilaterally via the neural connectome. This study aimed to investigate the differences in clinical characteristics and amygdala function between these two subtypes and to evaluate whether amygdala function could serve as a marker for subtype distinctions.

METHODS

Resting-state functional MRI data of 66 early-stage PD patients and 17 healthy controls (HC) were retrieved from the Parkinson's Progression Markers Initiative database. PD patients with REM Sleep Behavior Disorder (RBD) were classified as the body-first subtype, while those without RBD were classified as the brain-first subtype.

RESULTS

We found that body-first patients had a longer disease duration and more severe autonomic dysfunction compared to brain-first patients. Amygdala-related FC in brain-first patients was similar to that in the HC group, with both groups showing stronger FC between the bilateral amygdala and the right postcentral gyrus than body-first patients. Importantly, the abnormal amygdala-related FC was negatively correlated with SCOPA-Aut scores (r = -0.361, P = 0.002) in PD patients. ROC analysis indicated that the area under the curve for the FC was 0.834.

CONCLUSION

Our findings suggest that the amygdala-related FC may serve as an effective indicator to differentiate brain-first and body-first subtypes. Moreover, functional abnormalities in the amygdala contribute to autonomic dysfunction, rather than depression or anxiety in early-stage PD patients. Further validation of these findings in trials with larger cohorts is needed.

Increased excitatory amino acid transporter 2 levels in basolateral amygdala astrocytes mediate chronic stress-induced anxiety-like behavior

JOURNAL/nrgr/04.03/01300535-202506000-00024/figure1/v/2024-08-05T133530Z/r/image-tiff The conventional perception of astrocytes as mere supportive cells within the brain has recently been called into question by empirical evidence, which has revealed their active involvement in regulating brain function and encoding behaviors associated with emotions. Specifically, astrocytes in the basolateral amygdala have been found to play a role in the modulation of anxiety-like behaviors triggered by chronic stress. Nevertheless, the precise molecular mechanisms by which basolateral amygdala astrocytes regulate chronic stress-induced anxiety-like behaviors remain to be fully elucidated. In this study, we found that in a mouse model of anxiety triggered by unpredictable chronic mild stress, the expression of excitatory amino acid transporter 2 was upregulated in the basolateral amygdala. Interestingly, our findings indicate that the targeted knockdown of excitatory amino acid transporter 2 specifically within the basolateral amygdala astrocytes was able to rescue the anxiety-like behavior in mice subjected to stress. Furthermore, we found that the overexpression of excitatory amino acid transporter 2 in the basolateral amygdala, whether achieved through intracranial administration of excitatory amino acid transporter 2 agonists or through injection of excitatory amino acid transporter 2-overexpressing viruses with GfaABC1D promoters, evoked anxiety-like behavior in mice. Our single-nucleus RNA sequencing analysis further confirmed that chronic stress induced an upregulation of excitatory amino acid transporter 2 specifically in astrocytes in the basolateral amygdala. Moreover, through in vivo calcium signal recordings, we found that the frequency of calcium activity in the basolateral amygdala of mice subjected to chronic stress was higher compared with normal mice. After knocking down the expression of excitatory amino acid transporter 2 in the basolateral amygdala, the frequency of calcium activity was not significantly increased, and anxiety-like behavior was obviously mitigated. Additionally, administration of an excitatory amino acid transporter 2 inhibitor in the basolateral amygdala yielded a notable reduction in anxiety level among mice subjected to stress. These results suggest that basolateral amygdala astrocytic excitatory amino acid transporter 2 plays a role in in the regulation of unpredictable chronic mild stress-induced anxiety-like behavior by impacting the activity of local glutamatergic neurons, and targeting excitatory amino acid transporter 2 in the basolateral amygdala holds therapeutic promise for addressing anxiety disorders.

Distinct cortisol effects on item and associative memory across memory phases

Our daily lives are filled with stressful situations, which powerfully shape the way we form, consolidate, and retrieve episodic memories. As such, stress hormones affect different memory phases of both individual items and their associations, whether they are neutral or emotional. However, an interplay between all these factors in our memory of stressful events is still poorly understood. To address this conundrum, we employed a within-subject, double-blind, placebo-controlled design with exogenous cortisol administration (10 mg hydrocortisone) to affect different memory phases (pre-encoding, post-encoding, pre-retrieval). Our participants encoded neutral and emotional noun - image pairs. After a 24 h delay, we tested their memory for individual items (nouns) and their associations (nouns - objects). While accounting for baseline (no stress) memory performance, we found divergent cortisol effects on item and associative memory, depending on affected memory phase and on emotionality of memoranda. While post-encoding cortisol administration enhanced item memory, pre-encoding, and pre-retrieval cortisol administration impaired item memory. Similarly, pre-encoding cortisol administration impaired associative memory, but only for neutral stimuli. Moreover, we observed that both salivary cortisol levels and emotionality of memoranda modulated item and associative memory performance. These findings highlight a complex interplay of how stress hormone cortisol, throughout all memory phases, differently modulates item and associative memory of neutral and emotional events.

Interoception in Parkinson's disease: A narrative review and framework for translational research

Parkinson's disease (PD) is the second most common, and the fastest growing, neurodegenerative disease worldwide. Non-motor manifestations, particularly autonomic nervous system dysfunction, are common throughout the disease course, in some cases preceding motor symptom onset by years, and are often more disabling and harder to treat than motor symptoms and contribute significantly to disability. An understudied consequence of autonomic and visceral dysfunction in PD is interoception, the neural processing of internal organ system signals. Interoceptive processes form a foundational body-brain interface, mediating basic homeostatic reflexes and complex physiologic and behavioral adaptive responses to internal perturbations. Emerging evidence exists that interoception is impaired in some individuals with PD, potentially explaining why those who have objective evidence of autonomic dysfunction do not always report typical symptoms. Failure to recognize these impairments may lead to missed opportunities for early intervention, particularly in addressing 'silent' autonomic disturbances (e.g., orthostatic hypotension leading to sudden falls, dysphagia leading to aspiration pneumonia). In this narrative review, we synthesize current findings on the neuroanatomical networks underlying interoception, examine clinical manifestations of interoceptive dysfunction across multiple organ systems in PD, and identify key gaps in knowledge. We propose a translational research framework to enhance early detection, symptom management, and intervention strategies for PD. This framework integrates cognitive, mood, and autonomic dysfunctions with clinical factors (disease stage, duration, motor subtype, levodopa status) to understand interoceptive dysfunction within a translational model. This approach highlights novel opportunities for personalized care and improved therapeutic interventions in PD.

Vibrotactile auricular vagus nerve stimulation alters limbic system connectivity in humans: A pilot study

Vibration offers a potential alternative modality for transcutaneous auricular vagus nerve stimulation (taVNS). However, mechanisms of action are not well-defined. The goal of this pilot study was to evaluate the potential of vibrotactile stimulation of the outer ear as a method for activating central brain regions similarly to established vagal nerve stimulation methods. Seven patients with intractable epilepsy undergoing stereotactic electroencephalography (sEEG) monitoring participated in the study. Vibrotactile taVNS was administered across five vibration frequencies (2, 6, 12, 20, and 40 Hz) following a randomized stimulation pattern with 30 trials per frequency. Spectral coherence during stimulation was analyzed across theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), and broadband gamma (70-170 Hz) frequency bands. At the group level, vibrotactile taVNS significantly increased coherence in theta (effect sizes 6 Hz: r = 0.311; 20 Hz: r = 0.316; 40 Hz: r = 0.264) and alpha bands (effect sizes 20 Hz: r = 0.455; 40 Hz: r = 0.402). Anatomically, multiple limbic brain regions exhibited increased coherence during taVNS compared to baseline. The percentage of total electrode pairs demonstrating increased coherence was also quantified at the individual level. Twenty Hz vibration resulted in the highest percentage of responder pairs across low-frequency coherence measures, with a group-average of 33% of electrode pairs responding, though inter-subject variability was present. Overall, vibrotactile taVNS induced significant low-frequency coherence increases involving several limbic system structures. Further, parametric characterization revealed the presence of inter-subject variability in terms of identifying the vibration frequency with the greatest coherence response. These findings encourage continued research into vibrotactile stimulation as an alternative modality for noninvasive vagus nerve stimulation.

Microglial repopulation reverses radiation-induced cognitive dysfunction by restoring medial prefrontal cortex activity and modulating leukotriene-C4 synthesis

Cranial radiotherapy and environmental radiation exposure are associated with increased risk of cognitive dysfunction, including memory deficits and mood disorders, yet the underlying mechanisms remain poorly understood. In this study, we demonstrate that cranial irradiation induces hypoactivity in the medial prefrontal cortex (mPFC) of mice, leading to anxiety-like behaviors and memory impairments, which can be prevented by optogenetic activation of mPFC excitatory neurons. Radiaiton exposure also causes a significant reduction in microglial density within the mPFC, accompanied by morphological and transcriptional alterations in the remaining microglia. Notably, microglial repopulation, achieved through CSF1R antagonist-mediated depletion prior to irradiation and subsequent repopulation, restores mPFC neuronal acitivity and reverses cognitive and behavioral deficits. Integrated bulk RNA sequencing and microglial proteomic analysis of the mPFC reveal that microglial repopulation specifically modulates the leukotriene-C4 biosynthesis pathway, without significant changes in canonical pro-inflammatory cytokines or chemokines. Importantly, pharmacological inhibition of leukotriene-C4 synthase ameliorates radiation-induced anxiety and memory impairments. These findings identify leukotriene-C4 signaling as a critical mechanism underlying radiation-induced cognitive dysfunction and suggest that microglial repopulation and targted inhibition of leukotriene-C4 represent potential therapeutic strategies for mitigating radiation-associated cognitive disorders.

Structural plasticity of the contralesional subfields of hippocampus and amygdala in patients with IDH-mutant astrocytoma and oligodendroglioma

PURPOSE

To detect the structural plasticity of the contralesional hippocampus and amygdala in patients with unilateral IDH-mutant astrocytoma and oligodendroglioma, and to compare the differences between these two types of tumors.

METHODS

3D T1-weighted MRI images were collected from 46 patients with left-hemispheric tumors (IDH-mutant astrocytoma, n = 22; oligodendroglioma, n = 24) and 23 healthy controls (HCs). Volumetric differences in the subregional volumes of the hippocampus and amygdala were assessed using FreeSurfer software. The differences were compared across groups.

RESULTS

In comparison to HCs, patients with unilateral IDH-mutant astrocytoma and oligodendroglioma exhibited a significantly larger volume of the hippocampal fissure in the contralesional hippocampus (p = 0.021, p = 0.041). In the astrocytoma group, volumetric increases were also observed in the contralesional amygdala subregions, including the medial-nucleus (p = 0.009), central-nucleus (p = 0.011), and cortical-nucleus (p = 0.039). Compared to the oligodendroglioma group, the astrocytoma group demonstrated significantly larger gray matter volume in the subiculum head (p = 0.008) of the contralesional hippocampus, as well as in the anterior amygdaloid area (AAA) (p = 0.044), central-nucleus (p = 0.025), and cortical-nucleus (p = 0.021) of the contralesional amygdala.

CONCLUSION

These findings provide robust evidence of macrostructural plasticity in the contralateral hippocampus and amygdala in patients with unilateral IDH-mutant astrocytomas and oligodendrogliomas. Furthermore, the structural differences between tumor types may reflect distinct effects on brain plasticity and variations in tumor invasiveness. These insights could contribute to optimization of clinical management strategies and personalized cognitive rehabilitation strategies for glioma patients.

Physical Activity to Counter Age-Related Cognitive Decline: Benefits of Aerobic, Resistance, and Combined Training-A Narrative Review

BACKGROUND

With the increase in life expectancy, age-related cognitive decline has become a prevalent concern. Physical activity (PA) is increasingly being recognized as a vital non-pharmacological strategy to counteract this decline. This review aimed to (i) critically evaluate and synthesize the impact of different PA and exercise modalities (aerobic, resistance, and concurrent training) on cognitive health and overall well-being in older adults, (ii) discuss the influence of exercise intensity on cognitive functions, and (iii) elucidate the potential mechanisms through which PA and exercise may enhance or mitigate cognitive performance among older adults.

MAIN BODY

An exhaustive analysis of peer-reviewed studies pertaining to PA/exercise and cognitive health in older adults from January 1970 to February 2025 was conducted using PubMed, Scopus, Web of Science, PsycINFO, and MEDLINE. There is compelling evidence that aerobic and resistance training (RT) improve cognitive function and mental health in older adults, with benefits influenced by the type and intensity of exercise. Specifically, moderate-intensity aerobic exercise appears to bolster memory, executive functions, and mood regulation, potentially through increased cerebral blood flow, neurogenesis, and production of brain-derived neurotrophic factors in the hippocampus. Moderate-to-high-intensity RT acutely enhances visuospatial processing and executive functions, with chronic training promoting neurogenesis, possibly by stimulating insulin-like growth factor-1 and augmenting blood flow to the prefrontal cortex. Findings related to the effects of concurrent training on cognitive function and mental health are heterogeneous, with some studies reporting no significant impact and others revealing substantial improvements. However, emerging evidence indicates that the combination of concurrent training and cognitive tasks (i.e., dual tasks) is particularly effective, often outperforming aerobic exercise alone.

CONCLUSIONS

Regular aerobic and RT performance is beneficial for older adults to mitigate cognitive decline and enhance their overall well-being. Specifically, engaging in moderate-intensity aerobic exercises and moderate-to-high-intensity RT is safe and effective in improving cognitive function and mental health in this demographic. These exercises, which can be conveniently incorporated into daily routines, effectively enhance mental agility, memory, executive function, and mood. The findings related to concurrent training are mixed, with emerging evidence indicating the effectiveness of combined concurrent and cognitive tasks on cognitive health and well-being in older adults. Key Points - Moderate-intensity aerobic exercise is associated with significant improvements in cognitive function, mood regulation, and overall well-being in older adults. These benefits are linked to structural and functional changes in the brain such as increased hippocampal volume and elevated levels of brain-derived neurotrophic factor. - Moderate-to-high-intensity resistance training, both in acute and chronic forms, enhances cognitive performance in older adults, particularly in executive functions and visuospatial processing. Cognitive benefits, including improvements in information-processing speed, attention, and memory, can be sustained through regular training. - The effects of concurrent resistance and aerobic training on cognitive function in older adults are mixed. However, combining concurrent training with cognitive tasks (i.e., dual-task training) is particularly effective and often outperforms aerobic exercise alone. - Cognitive and well-being improvements from aerobic and resistance training are mediated by mechanisms such as increased cerebral blood flow and oxygen delivery, enhanced neurogenesis, reduced oxidative stress and inflammation, and positive hormonal changes. - While the optimal exercise dosage for promoting cognitive health in older adults remains undetermined, empirical evidence indicates a positive correlation between increased exercise dosage and cognitive health improvements.

Social stress enhances intuitive prosocial behavior in males while disrupting self-reward processing: Evidence from behavioral, computational, and neuroimaging studies

In this study, we present behavioral, computational, and neuroimaging evidence that social stress enhances intuitive prosocial value processing while impairing self-reward processing. When deciding on monetary rewards for individuals at various social distances, participants who exhibited elevated cortisol levels following a social stress task were more inclined to choose a disadvantageous unequal option. Neuroimaging data revealed that participants more likely to choose the disadvantageous unequal option exhibited increased encoding of other-regarding rewards in the ventral medial prefrontal cortex (mPFC), whereas the dorsal mPFC exhibited a decrease in encoding. Mediation analyses further indicated that both the ventral and dorsal mPFC indirectly mediated the relationship between heightened cortisol levels and a greater likelihood of choosing a disadvantageous unequal option. Additionally, effective connectivity analysis results demonstrated that cortisol has an excitatory effect on the dorsal mPFC via the ventral striatum, while simultaneously sending inhibitory signals to the dorsal mPFC via the dorsal striatum. These findings provide empirical evidence to clarify the ambiguity surrounding the effects of stress on prosocial decision-making, suggesting that social stress disrupts deliberative decision-making while simultaneously promoting intuitive prosocial motivation through the differential modulation of hierarchically organized cortico-striatal loops.

Dissociating and linking divergent effects of emotion on cognition: insights from current research and emerging directions

This century has witnessed unprecedented increasing interest in the investigation of emotion-cognition interactions and the associated neural mechanisms. The present review emphasizes the need to consider the various factors that can influence enhancing and impairing effects of emotion on cognition, in studies of both healthy and clinical groups. First, we discuss advances in understanding the circumstances in which emotion enhances or impairs cognition at different levels, both within the same processes (e.g., perception, episodic memory) and across different processes (i.e., episodic vs. working memory). Then, we discuss evidence regarding these opposing effects of emotion in a larger context, of the response to stressors, and linked to the role of individual differences (personality, genetic) affecting stress sensitivity. Finally, we also discuss evidence linking these opposing effects of emotion in a clinical group (PTSD), where they are both deleterious, and based on comparisons across groups with opposing affective biases: healthy aging (positive bias) vs. depression (negative bias). These issues have relevance for understanding mechanisms of emotion-cognition interactions in healthy functioning and in psychopathology, which can inspire training interventions to increase resilience and well-being.

Rosa multiflora fructus and its active compound ellagic acid improve depressive-like behaviors in mice via monoamine oxidase inhibition

Depression is a significant global health challenge, imposing severe social and economic burdens. Rosa multiflora fructus possesses a range of biological properties; however, its role in reducing stress hormone-induced depression remains unclear. This study examined the antidepressant effects of Rosa multiflora fructus extract (RMFE) on corticosterone (CORT)-induced depressive-like behaviors in mice and explored the underlying molecular mechanisms. ICR mice were administered CORT (40 mg/kg/day, i.p.) for 8 weeks to induce depressive-like behaviors. They were then treated with RMFE (100 or 300 mg/kg/day, p.o.) or selegiline (10 mg/kg/day, p.o.) as a positive control. RMFE treatment significantly alleviated depressive-like behaviors, as evaluated by the tail suspension and forced swimming tests. Furthermore, RMFE reduced hippocampal astrocyte hypertrophy and lowered the protein and mRNA expression of monoamine oxidase A and B (MAOA and MAOB). Phytochemical analysis using UPLC-MS/MS identified five flavonoids in RMFE, including ellagic acid (EA), hyperoside, isoquercetin, quercetin, and quercetin-3-glucuronide. In silico molecular docking revealed that these phenolic compounds interact with MAOA and MAOB, with EA exhibiting the strongest binding affinity. Consistently, EA administration effectively alleviated depressive-like behaviors and increased monoamine neurotransmitter levels in CORT-treated mice. These results suggest that RMFE exerts antidepressant effects by inhibiting MAO, restoring monoamine levels, and modulating hippocampal astrocytic hypertrophy, with EA identified as the primary bioactive compound driving its efficacy.

The Interplay Between Psychological and Neurobiological Predictors of Weight Regain: A Narrative Review

Introduction: Obesity is a global health problem requiring effective interventions to achieve weight loss and maintain it in the long term. A major challenge for clinicians is weight regain (WR), defined as progressive weight gain following successful weight loss. WR is affected by multiple factors, including psychological traits linked to specific brain alterations. Understanding these mechanisms is crucial in developing strategies to prevent WR and to ensure effective weight control. Objectives: This narrative review aims to gather current findings on the psychological and neurobiological determinants of WR and to discuss the interplay between these factors. Methods: A literature search was conducted on PubMed, Medline, and Web of Science for English-language studies published between December 1990 and November 2024. Results: WR is driven by interconnected psychological and neurobiological factors that influence eating behavior and the regulation of body weight. Certain personality traits and emotional patterns are associated with specific changes in brain activity, which together affect vulnerability to WR. Although distinct mechanisms can be identified, the complexity of homeostatic and nonhomeostatic appetite control suggests that no single factor predominates. Conclusions: This review highlights the dynamic interplay between psychological and neurobiological predictors of WR. However, due to the narrative nature of this review, the focus on selected determinants, and the limited quality and size of the available studies, further research is needed to comprehensively understand causality and to improve relapse prevention strategies.

Posttraining noradrenergic stimulation maintains hippocampal engram reactivation and episodic-like specificity of remote memory

Recent findings indicate that noradrenergic arousal maintains long-term episodic-like specificity of memory. However, the neural mechanism of how norepinephrine can alter the temporal dynamics of systems consolidation to maintain hippocampus dependency of remote memory is currently unknown. Memories are stored within ensembles of neurons that become activated during learning and display strengthened mutual plasticity and connectivity. This strengthened connectivity is believed to guide the coordinated reactivation of these neurons upon subsequent memory recall. Here, we used male transgenic FosTRAP2xtdTomato mice to investigate whether the noradrenergic stimulant yohimbine administered systemically immediately after an episodic-like object-in-context training experience maintained long-term memory specificity which was joined by an enhanced reactivation of training-activated cells within the hippocampus during remote retention testing. We found that saline-treated control mice time-dependently lost their episodic-like specificity of memory, which was associated with a shift in neuronal reactivation from the dorsal hippocampus to the prelimbic cortex at a 14-day retention test. Importantly, yohimbine-treated mice maintained episodic-like specificity of remote memory and retained high neuronal reactivation within the dorsal hippocampus, without a time-dependent increase in prelimbic cortex reactivation. These findings suggest that noradrenergic arousal shortly after training maintains episodic-like specificity of remote memory by strengthening the connectivity between training-activated hippocampal cells during consolidation, and provide a cellular model of how emotional memories remain vivid and detailed.

Affective Neuroscience Personality Scale (ANPS) in Children with Internalizing Disorders

Background/Objectives: This study of endophenotypes represents a new research approach to overcome the limits of a syndromic model to psychiatric diseases. The Affective Neuroscience Personality Scales (ANPS, 31) is a self-report questionnaire used to facilitate the transition from the syndromic to the endophenotypic model through the assessment of basic emotional systems described by Panksepp (1): SEEKING, PLAY, CARE, FEAR, RAGE, PANIC, and LUST. The ANPS was used with adults, but it may be important to investigate the expression of basic emotional systems in childhood clinical disorders. Methods: The present study compares the ANPS scores of a group of children (n = 71) with internalizing disorders (diagnoses of depression and anxiety) with those of a normative group (n = 208) (8-13 years). Conclusions: We found that the group with internalizing disorders showed significantly lower scores for SEEKING and PLAY and significantly higher scores for ANGER and SADNESS than the control group. Furthermore, depressed children reported significantly lower scores in the SEEKING, PLAY, CARE scales and higher scores in the ANGER and SADNESS scales than healthy children. The children with anxiety disorder had significantly lower scores in the SEEKING and PLAY scales and higher scores in the FEAR and SADNESS scales than control children. No significant effect was found in reference to the age of the children. The results indicate that the ANPS might be a useful instrument to assess the expression of emotional endophenotypes in childhood.

Advances in discerning the mechanisms underlying depression and resiliency: relation to the neurobiology of stress and the effects of antidepressants

Depression denotes a dysregulated stress response with significant mental and health implications. This review examines the neurobiological mechanisms underlying depression and resilience, focusing on how stress mediators influence vulnerability to severe stressors contrasted with resilience. We analyze structural and functional alterations in key brain regions, genetic factors, and potential therapeutic interventions. Understanding these mechanisms offers insights into preventing depression onset instead of solely treating its manifestations.

Elucidating the complexity of radiation-induced brain injury: comprehensive assessment of hippocampal and cortical impacts

PURPOSE

Radiation-induced brain injury (RIBI) poses significant clinical challenges, underscoring the limited mechanistic understanding in this field. This study systematically investigates both the genetic and metabolic alterations induced by RIBI and their differential regional impacts across brain structures.

METHODS

Mice received cranial irradiation with a single 30 Gy X-ray dose. Behavioral assessments, including the open field test (OFT), elevated plus maze test (EPM), and Morris water maze test (MWM), were conducted to evaluate the impact of RIBI on mouse behavior. Hippocampal and cortical tissues were subjected to transcriptomic and metabolomic analyses to identify alterations in gene expression and metabolic profiles.

RESULTS

Behavioral tests indicated that irradiated mice exhibited significant impairments in exploration behavior, anxiety levels, and memory capabilities compared to controls. Transcriptomic analysis identified 456 and 516 significantly altered genes in the hippocampus and cerebral cortex, respectively. Metabolomic analysis identified 253 and 335 significantly altered metabolites in the hippocampus and cerebral cortex, respectively. Integrated pathway analysis uncovered region-specific alterations, while also highlighting shared perturbations in pathways such as glycerophospholipid metabolism, cAMP signaling, and the TCA cycle, suggesting these pathways as key biological processes affected by RIBI.

CONCLUSIONS

This study delineates the genetic and metabolic alterations induced by RIBI in the hippocampus and cerebral cortex. Our findings reveal both region-specific and shared characteristics of RIBI, providing a foundation for understanding the differential effects of radiation-induced injury across brain regions.

Social stress increases anxiety by GluA1-dependent synaptic strengthening of ventral tegmental area inputs to the basolateral amygdala

BACKGROUND

Brain defensive mechanisms evolved to maintain low levels of state anxiety. However, risk factors such as stress exposure shifts activity within defensive circuits, resulting in increased anxiety. The amygdala is a crucial node for maintaining adaptive anxiety levels, and amygdala hyperactivity can lead to pathological anxiety through mechanisms that are not well understood.

METHODS

We used chronic social defeat stress (CSD) in mice. We combined anatomical tracing methods, patch-clamp recordings and optogenetics to probe how synaptic inputs from the ventral tegmental area (VTA) to the basolateral amygdala (BLA) are affected by CSD. We performed in vivo fiber photometry recordings to track inputs onto basolateral amygdala. Array tomography and electron microscopy were used to unravel the structural composition of VTA-BLA synapses.

RESULTS

We identified the VTA as a source of glutamatergic inputs to the BLA potentiated by stress. In turn, inputs from mPFC were not potentiated. BLA-projecting VTA glutamatergic neurons are activated by social stress, increasing their excitability and synaptic strength. In vivo potentiation of VTA glutamatergic inputs in the BLA is sufficient to increase anxiety. We showed that stress-induced synaptic strengthening is mediated by insertion of GluA1-containing AMPA receptors. Impeding GluA1 subunit trafficking in BLA neurons with VTA upstream inputs prevents stress-induced increase in synaptic firing and anxiety.

CONCLUSIONS

Potentiation of VTA inputs increases synaptic integration, enhancing amygdala activity and promoting maladaptive anxiety. Understanding the impact of amygdala hyperactivity could lead to targeted therapies, restoring circuit balance and offering new precision medicine approaches for anxiety disorders.

A global survey on the associations between the lockdown group, free memory recall and emotional responses during the COVID-19 lockdown

The unprecedented outbreak of the COVID-19 pandemic has altered the course of many lives, resulting in multiple health and social challenges. Due to the speed at which this pandemic spread, various public health 'lockdown' measures were introduced to mitigate its spread. The outcome of adherence to these measures has revealed the possible influence on individuals' varying cognitive abilities. Accordingly, this study aimed to explore the predictive relationships between lockdown responses and COVID-19 restrictions, memory recall performance, and associated emotional responses while examining the sociodemographic influences of age and sex. Participants were drawn from a secondary dataset of an international online survey study of 1634 individuals aged 18-75 years across 49 countries. Participants' demographic questionnaires, free memory recall, and hospital anxiety and depression scale scores were used to collect the data for analysis. Four-way MANOVA and hierarchical multiple regression were utilised to explore the mean differences and predict relationships between the study variables. Significant differences were found in memory recall performance and anxiety and depression scores across lockdown groups (the comply, sufferer, and defiant). Regression analysis indicated that age and gender were predictive markers of lockdown responses and anxiety (R2 = 0.14, F4,1625 = 66.15, p < .001, f2 = 0.17), while age was the only predictor of lockdown responses and depression association ([Formula: see text] = -0.78, t(1625) = -4.35, p < .001). Lockdown compliance was associated with better free recall (M = 8.51, SD = 6.38, p < .001; η2 = 0.01), lockdown suffering was associated with greater anxiety (M = 9.97, SD = 4.36, p < .001; η2 = 0.06), and lockdown deviance was associated with greater depression (M = 7.90, SD = 3.12, p < .001; η2 = 0.05). The current study provides valuable information on the mechanisms of cognitive interpretations and emotional arousal in individuals' social isolation responses to recent life stress and potential severe pandemics. This may support the need for robust interventions aimed at improving people's psychological appraisals associated with anxiety in preparation for any new potential waves or future pandemics.

Cross-ancestry and sex-stratified genome-wide association analyses of amygdala and subnucleus volumes

The amygdala is a small but critical multi-nucleus structure for emotion, cognition and neuropsychiatric disorders. Although genetic associations with amygdala volumetric traits have been investigated in sex-combined European populations, cross-ancestry and sex-stratified analyses are lacking. Here we conducted cross-ancestry and sex-stratified genome-wide association analyses for 21 amygdala volumetric traits in 6,923 Chinese and 48,634 European individuals. We identified 191 variant-trait associations (P < 2.38 × 10-9), including 47 new associations (12 new loci) in sex-combined univariate analyses and seven additional new loci in sex-combined and sex-stratified multivariate analyses. We identified 12 ancestry-specific and two sex-specific associations. The identified genetic variants include 16 fine-mapped causal variants and regulate amygdala and fetal brain gene expression. The variants were enriched for brain development and colocalized with mood, cognition and neuropsychiatric disorders. These results indicate that cross-ancestry and sex-stratified genetic association analyses may provide insight into the genetic architectures of amygdala and subnucleus volumes.

Neuroprotective Roles of Daidzein Through Extracellular Signal-Regulated Kinases Dependent Pathway In Chronic Unpredictable Mild Stress Mouse Model

Depression is a stress-related neuropsychiatric disorder causing behavioural, biochemical, molecular dysfunctions and cognitive impairments. Previous studies suggested connection between neuropsychiatric diseases like depression with estrogen and estrogen receptors (ER). Daidzein is a phytoestrogen that functions as mammalian estrogen and regulates gene expressions through extracellular signal-regulated kinases (ERKs) dependent pathway by activating ERβ. ERβ modulates stress responses, physiological processes by activating protein kinases and plays a significant role in various neurological diseases like depression. However, significant roles of daidzein in depression involving ERK1/2, pERK1/2, and mTOR still unknown. Herein, we examined neuroprotective role of daidzein in chronic unpredictable mild stress (CUMS) mouse model. CUMS model was prepared, and placed in six groups namely, control, CUMS, CUMS vehicle, CUMS DZ (Daidzein 1 mg/kgbw, orally), CUMS PHTPP (ERβ blocker, 0.3 mg/kgbw, i..p.) and CUMS Untreated. Supplementation of daidzein to CUMS mice exhibits decrease depressive and anxiety-like behaviour, improved motor coordination and memory. Further, immunofluorescence results showed daidzein improved ERK1/2, pERK1/2 and mTOR expressions in the cortex, hippocampus and medulla of stressed mice. SOD, catalase and acetylcholinesterase levels were also improved. Blocking of ERβ with PHTPP stressed mice showed deficits in behaviour, low expression of ERK1/2, pERK1/2 and mTOR, and no significant changes in SOD, catalase and acetylcholinesterase level. Collectively, this study suggests that daidzein may ameliorate depressive and anxiety-like behaviour through ERK downregulating pathway by activating ERβ through ERK1/2, pERK1/2 and mTOR. Such study may be useful to understand daidzein dependent neuroprotection through ERβ in depression.

A dual-pathway architecture for stress to disrupt agency and promote habit

Chronic stress can change how we learn and, thus, how we make decisions1-5. Here we investigated the neuronal circuit mechanisms that enable this. Using a multifaceted systems neuroscience approach in male and female mice, we reveal a dual-pathway, amygdala-striatal neuronal circuit architecture by which a recent history of chronic stress disrupts the action-outcome learning underlying adaptive agency and promotes the formation of inflexible habits. We found that the projection from the basolateral amygdala to the dorsomedial striatum is activated by rewarding events to support the action-outcome learning needed for flexible, goal-directed decision-making. Chronic stress attenuates this to disrupt action-outcome learning and, therefore, agency. Conversely, the projection from the central amygdala to the dorsomedial striatum mediates habit formation. Following stress, this pathway is progressively recruited to learning to promote the premature formation of inflexible habits. Thus, stress exerts opposing effects on two amygdala-striatal pathways to disrupt agency and promote habit. These data provide neuronal circuit insights into how chronic stress shapes learning and decision-making, and help understanding of how stress can lead to the disrupted decision-making and pathological habits that characterize substance use disorders and mental health conditions.

Abnormalities in cognitive-related functional connectivity can be used to identify patients with schizophrenia and individuals in clinical high-risk

BACKGROUND

Clinical high-risk (CHR) refers to prodromal phase before schizophrenia onset, characterized by attenuated psychotic symptoms and functional decline. They exhibit similar but milder cognitive impairments, brain abnormalities and eye movement change compared with first-episode schizophrenia (FSZ). These alterations may increase vulnerability to transitioning to the disease. This study explores cognitive-related functional connectivity (FC) and eye movement abnormalities to examine differences in the progression of schizophrenia.

METHODS

Thirty drug-naive FSZ, 28 CHR, and 30 healthy controls (HCs) were recruited to undergo resting-state functional magnetic resonance imaging (rs-fMRI). Connectome-based predictive modeling (CPM) was employed to extract cognitive-related brain regions, which were then selected as seeds to form FC networks. Support vector machine (SVM) was used to distinguish FSZ from CHR. Smooth pursuit eye-tracking tasks were conducted to assess eye movement features.

RESULTS

FSZ displayed decreased cognitive-related FC between right posterior cingulate cortex and right superior frontal gyrus compared with HCs and between right amygdala and left inferior parietal gyrus (IPG) compared with CHR. SVM analysis indicated a combination of BACS-SC and CFT-A scores, and FC between right amygdala and left IPG could serve as a potential biomarker for distinguishing FSZ from CHR with high sensitivity. FSZ also exhibited a wide range of eye movement abnormalities compared with HCs, which were associated with alterations in cognitive-related FC.

CONCLUSIONS

FSZ and CHR exhibited different patterns of cognitive-related FC and eye movement alteration. Our findings illustrate potential neuroimaging and cognitive markers for early identification of psychosis that could help in the intervention of schizophrenia in high-risk groups.

Sub-chronic administration of AM6545 enhances cognitive performance and induces hippocampal synaptic plasticity changes in naïve mice

BACKGROUND AND PURPOSE

There is evidence of crosstalk between the brain and peripheral tissues. However, how the periphery contributes to brain function is not well understood. The cannabinoid CB1 receptor is classically pictured to have a relevant role in cognitive function. We previously demonstrated a novel mechanism where acute administration of the CB1 receptor antagonist AM6545, largely restricted to the periphery, prolonged memory persistence in mice. Here, we have assessed the effects of repeated exposure to AM6545 on cognitive improvements.

EXPERIMENTAL APPROACH

We evaluated, in young adult male and female mice, the behavioural consequences of sub-chronic treatment with AM6545. An unbiased transcriptomic analysis, as well as electrophysiological and biochemical studies, was carried out to elucidate the central cellular and molecular consequences of such action at peripheral receptors.

KEY RESULTS

Sub-chronic AM6545 enhanced memory in low and high arousal conditions in male and female mice. Executive function was facilitated after repeated AM6545 administration in male mice. Transcriptional analysis of hippocampal synaptoneurosomes from treated mice revealed a preliminary, sex-dependent, modulation of synaptic transcripts by AM6545. Notably, AM6545 occluded long-term potentiation in CA3-CA1 synapses while enhancing input-output relation in male mice. This was accompanied by an increase in hippocampal expression of Bdnf and Ngf.

CONCLUSION AND IMPLICATIONS

Our results showed that repeated administration of AM6545 contributed to the modulation of memory persistence, executive function and hippocampal synaptic plasticity in mice, further indicating that peripheral CB1 receptors could act as a target for a novel class of nootropic compounds.

Effect of stress on neuronal cell: Morphological to molecular approach

Stress can be characterized as any perceived or actual threat that necessitates compensatory actions to maintain homeostasis. It can alter an organism's behavior over time by permanently altering the composition and functionality of brain circuitry. The amygdala and prefrontal cortex are two interrelated brain regions that have been the focus of initial research on stress and brain structural and functional plasticity, with the hippocampus serving as the entry point for most of this knowledge. Prolonged stress causes significant morphological alterations in important brain regions such as the hippocampus, amygdala, and prefrontal cortex. Memory, learning, and emotional regulation are among the cognitive functions that are adversely affected by these changes, including neuronal shrinkage, dendritic retraction, and synaptic malfunction. Stress perturbs the equilibrium of neurotransmitters, neuronal plasticity, and mitochondrial function at the molecular level. On the other hand, chronic stress negatively impacts physiology and can result in neuropsychiatric diseases. Recent molecular research has linked various epigenetic processes, such as DNA methylation, histone modifications, and noncoding RNAs, to the dysregulation of genes in the impacted brain circuits responsible for the pathophysiology of chronic stress. Numerous disorders, including neurodegenerative diseases (NDDs) including Alzheimer's, amyotrophic lateral sclerosis, Friedreich's ataxia, Huntington's disease, multiple sclerosis, and Parkinson's disease, have been linked to oxidative stress as a possible cause.

Genetic and Environmental Influences on Anxiety Disorders: A Systematic Review of Their Onset and Development

Fear is an emotion most humans feel throughout their lifetime, often without knowing its exact cause. Fear is considered a behavioural act to escape a potentially threatening situation, whereas anxiety is distinguished by the lack of actual stimuli and, more so, the threat of potential stimuli. Fear and anxiety are two distinct emotions which warrant separate classifications. Understanding both the genetic and environmental influences which contribute to anxiety disorder onset and development can aid in prevention, diagnosis and management; it may also play a role in helping patients further understand their diagnosis and guide future research. This review examines genetic and environmental contributions to the onset and development of anxiety disorders and explores their implications for treatments and further research. An extensive search of databases, including PubMed, Web of Science and Google Scholar, using specific search terms led to the collection of a large number of studies prior to further screening. The inclusion criteria were: studies written in English, full-text available, human studies, and studies conducted within the last 10 years (at the time of writing). The exclusion criteria were: animal studies, studies with a focus on neurological anatomy rather than anxiety disorders, and studies including depressive or other psychological disorders. Using a cross-sectional approach allowed for the strengths to be summarised whilst considering the limitations of the research. The studies were screened for limitations and some of these were stated within the research, whilst others had to be interpreted using a subset of pre-formulated questions to ensure reproducibility. Variables such as the main outcomes, conclusions and limitations were tabulated to guide the interpretation of these studies. Genetic predispositions were linked to specific gene polymorphisms or familial abnormalities in neurological anatomy and often correlated with the likelihood of the onset of anxiety disorders or contributed to the severity of symptoms. Environmental influences were found to affect the functioning of the brain and some studies established the impacts that therapies have on brain function. The majority of studies have implicated that a combination of genetics and environment have an effect on anxiety disorders, with one study suggesting that a single traumatic event can lead to alterations in the function of specific genes related to anxiety disorders. Both genetic and environmental factors contribute to the onset, development and severity of anxiety disorders, with environmental triggers often influencing the phenotypic expression of these disorders. Further research would benefit from determining specific processes which lead to the onset of anxiety disorders to facilitate their detection and intervention before resulting in life-long and generational consequences. Studies including larger sample sizes and varied subjects would be advantageous in the future.

On the role of epigenetic modifications of HPA axis in posttraumatic stress disorder and resilience

Stress is a fundamental adaptive response that invokes amygdala and hypothalamus-pituitary-adrenal (HPA) axis along with other brain regions. Extreme or chronic stress, however, can result in a multitude of neuropsychiatric disorders, including anxiety, paranoia, bipolar disorder (BP), major depressive disorder (MDD), and posttraumatic stress disorder (PTSD). Despite widespread exposure to trauma (70.4%), the incidence of PTSD is relatively low (6.8%), suggesting that either individual susceptibility or adaptability driven by epigenetic and genetic mechanisms are likely at play. PTSD takes hold from exposure to traumatic events, such as death threats or severe abuse, with its severity being impacted by the magnitude of trauma, its frequency, and the nature. This comprehensive review examines how traumatic experiences and epigenetic modifications in hypothalamic-pituitary axis (HPA), such as DNA methylation, histone modifications, noncoding RNAs, and chromatin remodeling, are transmitted across generations, and impact genes such as FKBP prolyl isomerase 5 (FKBP5), nuclear receptor subfamily 3 group C member 1 (NR3C1), brain-derived neurotrophic factor (BDNF), and solute carrier family 6 member 4 (SLC6A4). It also provides a comprehensive overview on trauma reversal, resilience mechanisms, and pro-resilience factors such as histone acetyltransferases (HATs)/histone deacetylases (HDACs) ratio, dehydroepiandrosterone (DHEA)/cortisol ratio, testosterone levels, and neuropeptide Y, thus highlighting potential therapeutic approaches for trauma-related disorders. The studies highlighted here underscore the narrative, for the first time, that the examination and treatment of PTSD and other depressive disorders must invoke a multitude of approaches to seek out the most effective and personalized strategies. We also hope that the discussion emanating from this review will also inform government policies directed toward intergenerational trauma and PTSD.

Transcutaneous Auricular Vagus Nerve Stimulation Enhances Emotional Processing and Long-Term Recognition Memory: Electrophysiological Evidence Across Two Studies

Recently, we found that continuous transcutaneous auricular vagus nerve stimulation (taVNS) facilitates the encoding and later recollection of emotionally relevant information, as indicated by differences in the late positive potential (LPP), memory performance, and late ERP Old/New effect. Here, we aimed to conceptually replicate and extend these findings by investigating the effects of different time-dependent taVNS stimulation protocols. In Study 1, an identical paradigm to our previous study was employed with interval stimulation (30-s on/off). Participants viewed unpleasant and neutral scenes on two consecutive days while receiving taVNS or sham stimulation and completed a recognition test 1 week later. Replicating previous results, unpleasant images encoded under taVNS, compared to sham stimulation, elicited larger amplitudes in an earlier window of the LPP during encoding, as well as more pronounced late Old/New differences. However, no effects of taVNS on memory performance were found. In Study 2, we followed up on these findings by synchronizing the stimulation cycle with image presentation to determine the taVNS effects for images encoded during the on and off cycles. We could replicate the enhancing effects of taVNS on brain potentials (early LPP and late Old/New differences) and found that taVNS improved recollection-based memory performance for both unpleasant and neutral images, independently of the stimulation cycle. Overall, our results suggest that taVNS increases electrophysiological correlates of emotional encoding and retrieval in a time-independent manner, substantiating the vagus nerve's role in emotional processing and memory formation, opening new venues for improving mnemonic processes in both clinical and non-clinical populations.

The impact of distal stress on the spontaneous recovery of conditioned defensive responses

Intense and chronic stress strengthens fear memories and increases the risk for mental disorders. Often stressful situations are experienced long before the appearance of the symptoms, but so far, little has been investigated on how distal stress alters fear memories. In a four-day paradigm, 131 healthy individuals were either assigned to the stress-group by means of the socially evaluated cold-pressor test (SECPT) or to the sham-group (control condition). Twenty-four hours later, participants underwent fear acquisition during which two shapes were presented. The first shape (conditioned stimulus, CS+) was associated with an electro-tactile stimulation (unconditioned stimulus, US), whereas the second shape (CS-) were presented alone. During extinction training, both shapes were presented while the US was omitted. To investigate if stress induction alters extinction recall differently depending on the passage of time, participants were tested either one day (recent) or 15 days (remote) after extinction training. Learning was quantified via subjective ratings, startle reflex and skin conductance response. While we found successful acquisition and extinction of the conditioned defensive responses, there was no effect of stress on these learning processes. Stress induction did not alter the spontaneous recovery of the conditioned defensive verbal responses but of the physiological responses as stressed individuals tested two weeks after extinction training showed startle potentiation to CS + vs. CS-. In conclusion, distal stress, even if mild, can strengthen fear memories and weaken extinction memory by the passage of time. This could be a possible mechanism facilitating the onset of stress-related and anxiety disorders.

Functional network disruptions in youth with concussion using the Adolescent Brain Cognitive Development study

OBJECTIVE

This study aimed to compare psychosocial outcomes and functional neuroimaging among youth with concussion, youth with anxiety, and age- and sex-matched controls.

METHODS

Using archival data from the Adolescent Brain Cognitive DevelopmentSM Study, we analyzed between-group differences in psychosocial outcomes measured by the Child Behavior Checklist's internalizing and externalizing problem scales, and assessed brain function using resting-state fMRI network-region connectivity (specifically frontoparietal network (FPN) and default mode network (DMN) connectivity with the amygdala).

RESULTS

Significant differences in psychosocial outcomes were found across all groups, with the anxiety group reporting the most internalizing problems, followed by the concussion group which significantly differed from controls. Additionally, FPN-amygdala connectivity was significantly reduced in the concussion group only; this reduced connectivity did not predict psychosocial outcomes across groups.

CONCLUSION

This study provided preliminary findings that brain connectivity is reduced exclusively in individuals with concussion. Although disruptions were observed in the concussion group, further investigation is warranted to understand how disruptions may be associated with concussion symptoms. Studies that utilize well-defined control and study groups, and comprehensive cognitive and mental health measures will offer a deeper understanding of the relationship between brain function and psychosocial outcomes.

Human single-neuron activity is modulated by intracranial theta burst stimulation of the basolateral amygdala

Direct electrical stimulation of the human brain has been used for numerous clinical and scientific applications. Previously, we demonstrated that intracranial theta burst stimulation (TBS) of the basolateral amygdala (BLA) can enhance declarative memory, likely by modulating hippocampal-dependent memory consolidation. At present, however, little is known about how intracranial stimulation affects activity at the microscale. In this study, we recorded intracranial EEG data from a cohort of patients with medically refractory epilepsy as they completed a visual recognition memory task. During the memory task, brief trains of TBS were delivered to the BLA. Using simultaneous microelectrode recordings, we isolated neurons in the hippocampus, amygdala, orbitofrontal cortex, and anterior cingulate cortex and tested whether stimulation enhanced or suppressed firing rates. Additionally, we characterized the properties of modulated neurons, patterns of firing rate coactivity, and the extent to which modulation affected memory task performance. We observed a subset of neurons (~30%) whose firing rate was modulated by TBS, exhibiting highly heterogeneous responses with respect to onset latency, duration, and direction of effect. Notably, location and baseline activity predicted which neurons were most susceptible to modulation, although the impact of this neuronal modulation on memory remains unclear. These findings advance our limited understanding of how focal electrical fields influence neuronal firing at the single-cell level and motivate future neuromodulatory therapies that aim to recapitulate specific patterns of activity implicated in cognition and memory.

Memory Under Stress: From Adaptation to Disorder

Stressful events are ubiquitous in everyday life. Exposure to these stressors initiates the temporally orchestrated release of a multitude of hormones, peptides, and neurotransmitters that target brain areas that have been critically implicated in learning and memory. This review summarizes recent insights on the profound impact of stress on 4 fundamental processes of memory: memory formation, memory contextualization, memory retrieval, and memory flexibility. Stress mediators instigate dynamic alterations in these processes, thereby facilitating efficient responding under stress and the creation of a decontextualized memory representation that can effectively aid coping with novel future threats. While they are generally adaptive, the same stress-related changes may contribute to the rigid behaviors, uncontrollable intrusions, and generalized fear responding seen in anxiety disorders and posttraumatic stress disorder. Drawing on recent discoveries in cognitive neuroscience and psychiatry, this review discusses how stress-induced alterations in memory processes can simultaneously foster adaptation to stressors and fuel psychopathology. The transition from adaptive to maladaptive changes in the impact of stress on memory hinges on the nuanced interplay of stressor characteristics and individual predispositions. Thus, taking individual differences in the cognitive response to stressors into account is essential for any successful treatment of stress-related mental disorders.

Building Resilience: The Stress Response as a Driving Force for Neuroplasticity and Adaptation

People exhibit an extraordinary capacity to adjust to stressful situations. Here, we argue that the acute stress response is a major driving force behind this adaptive process. In addition to immediately freeing energy reserves, facilitating a rapid and robust neurocognitive response, and helping to reinstate homeostasis, the stress response also critically regulates neuroplasticity. Therefore, understanding the healthy acute stress response is crucial for understanding stress resilience-the maintenance or rapid recovery of mental health during and after times of adversity. Contemporary resilience research differentiates between resilience factors and resilience mechanisms. Resilience factors refer to a broad array of social, psychological, or biological variables that are stable but potentially malleable and predict resilient outcomes. In contrast, resilience mechanisms refer to proximate mechanisms activated during acute stress that enable individuals to effectively navigate immediate challenges. In this article, we review literature related to how neurotransmitter and hormonal changes during acute stress regulate the activation of resilience mechanisms. We integrate literature on the timing-dependent and neuromodulator-specific regulation of neurocognition, episodic memory, and behavioral and motivational control, highlighting the distinct and often synergistic roles of catecholamines (dopamine and norepinephrine) and glucocorticoids. We conclude that stress resilience is bolstered by improved future predictions and the success-based reinforcement of effective coping strategies during acute stress. The resulting generalized memories of success, controllability, and safety constitute beneficial plasticity that lastingly improves self-control under stress. Insight into such mechanisms of resilience is critical for the development of novel interventions focused on prevention rather than treatment of stress-related disorders.

Architecturally Mediated Allostasis and Neurosustainability: A Proposed Theoretical Framework for the Impact of the Built Environment on Neurocognitive Health

The global rise in mental health-related disorders represents a significant health and wellbeing challenge, imposing a substantial social and economic burden on individuals, communities, and healthcare systems. According to the World Health Organization, one in four people globally will be affected by mental or neurological disorders at some point in their lives, highlighting a significant global health concern that warrants carefully considered and innovative responses. While mental health challenges arise from complex, multifaceted factors, emerging research indicates that the built environment-the architecture of our homes, workplaces, and public spaces-may exert a critical but underappreciated influence on mental health outcomes. This paper outlines a novel theoretical framework for how visual stressors in the built environment might trigger neurophysiological stress responses via the HPA and SAM axes, potentially contributing over time to allostatic load. In this paper, it is proposed that chronic physiological strain can alter neuroplastic processes and neurogenesis in key brain regions-such as the hippocampus, prefrontal cortex (PFC), anterior cingulate cortex (ACC), and amygdala-thereby affecting cognitive health, emotional regulation, and overall mental wellbeing. Drawing on the principle of neurosustainability, this paper suggests that long-term exposure to stress-inducing environments may create feedback loops, particularly involving the amygdala, that have downstream effects on other brain areas and may be linked to adverse mental health outcomes such as depression. By presenting this framework, this paper aims to inspire further inquiry and applied experimental research into the intersection of neurophysiology, mental health, and the built environment, with a particular emphasis on rigorous testing and validation of the proposed mechanisms, that may then be translated into practical architectural design strategies for supporting health and wellbeing. In doing so, it is hoped that this work may contribute to a more holistic approach to improving mental health that integrates the creation of nurturing, resilient spaces into the broader public health agenda.

Early-life stress induces persistent astrocyte dysfunction associated with fear generalisation

Early-life stress can have lifelong consequences, enhancing stress susceptibility and resulting in behavioural and cognitive deficits. While the effects of early-life stress on neuronal function have been well-described, we still know very little about the contribution of non-neuronal brain cells. Investigating the complex interactions between distinct brain cell types is critical to fully understand how cellular changes manifest as behavioural deficits following early-life stress. Here, using male and female mice we report that early-life stress induces anxiety-like behaviour and fear generalisation in an amygdala-dependent learning and memory task. These behavioural changes were associated with impaired synaptic plasticity, increased neural excitability, and astrocyte hypofunction. Genetic perturbation of amygdala astrocyte function by either reducing astrocyte calcium activity or reducing astrocyte network function was sufficient to replicate cellular, synaptic, and fear memory generalisation associated with early-life stress. Our data reveal a role of astrocytes in tuning emotionally salient memory and provide mechanistic links between early-life stress, astrocyte hypofunction, and behavioural deficits.

Introduction to neurobiology and pharmacology of stress

In order to improve individual and community health outcomes, stress research is crucial for developing our understanding of human biology, psychology, and social dynamics. It also informs therapeutic practices, public health campaigns, and educational activities. The chapter explores how neurotransmitters, including glutamate, GABA, adrenaline, norepinephrine, serotonin, dopamine, and adrenaline, mediate stress responses, impact mood and behavior, and play a part in a number of stress-related disorders. The relevance of focused research and therapy approaches aimed at reestablishing equilibrium within these systems is highlighted by the fact that dysregulation of these neurotransmitters can exacerbate health problems. Additionally, it is investigated how the amygdala, hippocampus, and prefrontal cortex interact to process emotions, build resilience, and determine an individual's susceptibility to stress. These interactions are regulated by both neuroplasticity and hereditary and epigenetic factors. The chapter discusses the pharmaceutical approach to stress management, which includes a variety of drugs such as beta-blockers, anxiolytics, and antidepressants that work by targeting different neurotransmitter systems to reduce anxiety and mood disorders. Even while these therapies work, they may have negative consequences and side effects that should be carefully considered in clinical settings. The chapter promotes a comprehensive approach to stress management that combines medication, lifestyle changes, psychotherapy, and stress-reduction methods. Healthcare workers can improve patient care and ultimately the health and quality of life for people with stress-related disorders by knowing the complexity of pharmaceutical therapies and how they affect the stress response.

Microbial metabolites tune amygdala neuronal hyperexcitability and anxiety-linked behaviors

Changes in gut microbiota composition have been linked to anxiety behavior in rodents. However, the underlying neural circuitry linking microbiota and their metabolites to anxiety behavior remains unknown. Using male C57BL/6J germ-free (GF) mice, not exposed to live microbes, increased anxiety-related behavior was observed correlating with a significant increase in the immediate early c-Fos gene in the basolateral amygdala (BLA). This phenomenon coincided with increased intrinsic excitability and spontaneous synaptic activity of BLA pyramidal neurons associated with reduced small conductance calcium-activated potassium (SK) channel currents. Importantly, colonizing GF mice to live microbes or the microbial-derived metabolite indoles reverted SK channel activities in BLA pyramidal neurons and reduced the anxiety behavioral phenotype. These results are consistent with a molecular mechanism by which microbes and or microbial-derived indoles, regulate functional changes in the BLA neurons. Moreover, this microbe metabolite regulation of anxiety links these results to ancient evolutionarily conserved defense mechanisms associated with anxiety-related behaviors in mammals.

Enhancing Military Performance and Stress Management Through Mindfulness Training: The Role of Fronto-Limbic Network and Sequential Mediation Analysis

Mindfulness training (MT) has been shown to be effective at managing emotions and stress. However, the underlying neural mechanism of MT is yet unclear and attempts to explore the effects of MT on both psychological factors and performance outcomes remain unexplored. Physiological questionnaire, performance measures, and EEG-based Functional connectivity (FC) in the fronto-limbic network were analyzed in both the MT (N = 39) and control (N = 43) groups. Statistical analyses were conducted to evaluate group-wise differences, within-group longitudinal change, and sequential mediation effects. MT group maintained their stress coping capacity and demonstrated improved performance during the military training weeks. There was an increase in FC between the frontal and limbic regions in all frequency bands (i.e., delta, theta, alpha, and beta) in the MT group, yielding a higher FC than the control group in the final week. Furthermore, changes in these FC and changes in stress coping capacities played a sequential mediation role in the association between the MT and changes in military performance. This study demonstrated that MT was effective for military personnel under stressful conditions, in terms of managing stress coping capacity via changes in fronto-limbic FC, and improving task performance.

Post-retrieval noradrenergic activation impairs subsequent memory depending on cortico-hippocampal reactivation

When retrieved, seemingly stable memories can become sensitive to significant events, such as acute stress. The mechanisms underlying these memory dynamics remain poorly understood. Here, we show that noradrenergic stimulation after memory retrieval impairs subsequent remembering, depending on hippocampal and cortical signals emerging during retrieval. In a three-day study, we measured brain activity using fMRI during initial encoding, 24 hr-delayed memory cueing followed by pharmacological elevations of glucocorticoid or noradrenergic activity, and final recall. While post-retrieval glucocorticoids did not affect subsequent memory, the impairing effect of noradrenergic arousal on final recall depended on hippocampal reactivation and category-level reinstatement in the ventral temporal cortex during memory cueing. These effects did not require a reactivation of the original memory trace and did not interact with offline reinstatement during rest. Our findings demonstrate that, depending on the retrieval-related neural reactivation of memories, noradrenergic arousal after retrieval can alter the future accessibility of consolidated memories.

A Scoping Review of Corticosterone-Induced Changes in Ionotropic Glutamate Receptor Levels and Localization in the Rodent Brain: Implications for the Auditory System

BACKGROUND

The ionotropic glutamate receptor AMPA (AMPAR) mediates fast excitatory synaptic transmission and regulates synaptic strength in various parts of the CNS. Emotional challenges can affect these processes by influencing AMPAR levels and localization via stress hormones, resulting, e.g., in behavioral changes. AMPARs are essential for auditory processing, but their response to stress hormones in the central or peripheral auditory system remains poorly understood. Therefore, this scoping review examines the effects of corticosterone (CORT), a primary stress hormone in rodents, on AMPA receptor levels and localization in the rodent nervous system and considers potential implications for the auditory system.

METHODS

We systematically searched PubMed, Web of Science, and OVID EMBASE using MeSH terms related to AMPA receptors and corticosterone. Studies were screened based on predefined inclusion criteria, including original research published in English that focused on AMPA receptor subunits (e.g., GluR1-4, GluA1-4, Gria1-4). Of 288 articles screened, 17 met the criteria for final analysis.

RESULTS

No reports were found regarding CORT action in the auditory system. Three main experimental models used in the included research were identified: neuronal cultures, isolated tissue cultures, and animal models. Generally, short-term CORT exposure increases AMPAR surface localization and mobility in neuronal cultures, especially in the hippocampus and prefrontal cortex. However, results from animal models were inconsistent due to variations in experimental design and other factors. The isolated tissue study did not provide sufficient data for clear conclusions.

CONCLUSIONS

Variability in experimental models limits our ability to draw definitive conclusions about the effects of CORT on AMPARs across different regions of the nervous system. The differences in live animal studies highlight the need for standardized methods and reporting. Since AMPARs play a crucial role in auditory processing, CORT-induced changes in neuronal cultures may occur in the auditory system. Further research is needed to explore the specific responses of AMPAR subunits and how stress hormones may influence auditory disorders, which could help identify potential treatment strategies.

Stress disrupts engram ensembles in lateral amygdala to generalize threat memory in mice

Stress induces aversive memory overgeneralization, a hallmark of many psychiatric disorders. Memories are encoded by a sparse ensemble of neurons active during an event (an engram ensemble). We examined the molecular and circuit processes mediating stress-induced threat memory overgeneralization in mice. Stress, acting via corticosterone, increased the density of engram ensembles supporting a threat memory in lateral amygdala, and this engram ensemble was reactivated by both specific and non-specific retrieval cues (generalized threat memory). Furthermore, we identified a critical role for endocannabinoids, acting retrogradely on parvalbumin-positive (PV+) lateral amygdala interneurons in the formation of a less-sparse engram and memory generalization induced by stress. Glucocorticoid receptor antagonists, endocannabinoid synthesis inhibitors, increasing PV+ neuronal activity, and knocking down cannabinoid receptors in lateral amygdala PV+ neurons restored threat memory specificity and a sparse engram in stressed mice. These findings offer insights into stress-induced memory alterations, providing potential therapeutic avenues for stress-related disorders.

Hindbrain networks: Exploring the hidden anxiety circuits in rodents

Anxiety disorders are multifaceted conditions that engage numerous brain regions and circuits. While the hindbrain is pivotal in fundamental biological functions, its role in modulating emotions has been underappreciated. This review will uncover critical targets and circuits within the hindbrain that are essential for both anxiety and anxiolytic effects, expanding on research obtained through behavioral tests. The bidirectional neural pathways between the hindbrain and other brain regions, with a spotlight on vagal afferent signaling, provide a crucial framework for unraveling the neural mechanisms underlying anxiety. Exploring neural circuits within the hindbrain can help to unravel the neurobiological mechanisms of anxiety and elucidate differences in the expression of these circuits between genders, thereby providing valuable insights for the development of future anxiolytic drugs.

Multi-region processing during sleep for memory and cognition

Over the past decades, the understanding of sleep has evolved to be a fundamental physiological mechanism integral to the processing of different types of memory rather than just being a passive brain state. The cyclic sleep substates, namely, rapid eye movement (REM) sleep and non-REM (NREM) sleep, exhibit distinct yet complementary oscillatory patterns that form inter-regional networks between different brain regions crucial to learning, memory consolidation, and memory retrieval. Technical advancements in imaging and manipulation approaches have provided deeper understanding of memory formation processes on multi-scales including brain-wide, synaptic, and molecular levels. The present review provides a short background and outlines the current state of research and future perspectives in understanding the role of sleep and its substates in memory processing from both humans and rodents, with a focus on cross-regional brain communication, oscillation coupling, offline reactivations, and engram studies. Moreover, we briefly discuss how sleep contributes to other higher-order cognitive functions.

Microglia Morphology in the Developing Primate Amygdala and Effects of Early Life Stress

A unique pool of immature glutamatergic neurons in the primate amygdala, known as the paralaminar nucleus (PL), are maturing between infancy and adolescence. The PL is a potential substrate for the steep growth curve of amygdala volume during this developmental period. A microglial component is also embedded among the PL neurons and likely supports local neuronal maturation and emerging synaptogenesis. Microglia may alter neuronal growth following environmental perturbations such as stress. Using multiple measures in rhesus macaques, we found that microglia in the infant primate PL had relatively large somas and a small arbor size. In contrast, microglia in the adolescent PL had a smaller soma and a larger dendritic arbor. We then examined microglial morphology in the PL after a novel maternal separation protocol, to examine the effects of early life stress. After maternal separation, the microglia had increased soma size, arbor size, and complexity. Surprisingly, strong effects were seen not only in the infant PL, but also in the adolescent PL from subjects who had experienced the separation many years earlier. We conclude that under normal maternal-rearing conditions, PL microglia morphology tracks PL neuronal growth, progressing to a more "mature" phenotype by adolescence. Maternal separation has long-lasting effects on microglia, altering their normal developmental trajectory, and resulting in a "hyper-ramified" phenotype that persists for years. We speculate that these changes have consequences for neuronal development in young primates.

Behavioral disorders in multiple sclerosis: a comprehensive review

Multiple sclerosis (MS) is a heterogenous autoimmune-mediated disease of the central nervous system (CNS) characterized by inflammation, demyelination and chronic progressive neurodegeneration. Among its broad and unpredictable range of neuropsychiatric symptoms, behavioral changes are common, even from the early stages of the disease, while they are associated with cognitive deficits in advanced MS. According to DSM-5, behavioral disorders include attention deficits, oppositional, defiant and conduct disorders, anxiety, panic, obsessive-compulsive disorders (OCD), disruptive and emotional disorders, while others include also irritability, agitation, aggression and executive dysfunctions. Approximately 30 to 80% of individuals with MS demonstrate behavioral changes associated with disease progression. They are often combined with depression and other neuropsychiatric disorders, but usually not correlated with motor deficits, suggesting different pathomechanisms. These and other alterations contribute to disability in MS. While no specific neuropathological data for behavioral changes in MS are available, those in demyelination animal models share similarities with white matter and neuroinflammatory abnormalities in humans. Neuroimaging revealed prefrontal cortical atrophy, interhemispheric inhibition and disruption of fronto-striato-thalamic and frontoparietal networks. This indicates multi-regional patterns of cerebral disturbances within the MS pathology although their pathogenic mechanisms await further elucidation. Benefits of social, psychological, behavioral interventions and exercise were reported. Based on systematical analysis of PubMed, Google Scholar and Cochrane library, current epidemiological, clinical, neuroimaging and pathogenetic evidence are reviewed that may aid early identification of behavioral symptoms in MS, and promote new therapeutic targets and strategies.

Glutamatergic neurons of basolateral amygdala mediate increased exploratory behaviors produced by mildly chronic restraint stress in adolescent mice

In response to stressors, individuals manifest varied behavioral responses directed toward satisfying physiological survival needs. Although the enduring effects of adolescent stress on both humans and animals are well-documented, the underlying mechanisms remain insufficiently elucidated. Utilizing immunofluorescence, viral injections, and brain slice electrophysiological recordings, we have delineated that heightened excitability among glutamatergic neurons in the basolateral amygdala (BLA) is responsible for inducing heightened exploratory behaviors in adolescent mice subjected to mild, chronic restraint stress. Activation of BLA glutamatergic neurons through chemogenetics increases exploratory behaviors in emotional assessments, whereas inhibition of these neurons diminishes exploratory behaviors in measures such as the open field and elevated plus maze test. Furthermore, an upregulation of glutamate receptor expression and a concomitant downregulation of GABA receptor expression in BLA glutamatergic neurons have been associated with enhanced exploratory behaviors, validated through in vivo receptor antagonists. These findings unveil the protective role of mild stress exposure during adolescence against adversity, providing novel insights for addressing stressful events.

Emotion Regulation Under Stress: A Social Processing and Memory Perspective

Research on emotion regulation often focuses on cognitively effortful self-regulation strategies, but exposure to stress has been shown to interfere with the underlying mechanisms supporting such processes. Understanding alternative strategies that potentially bolster emotion regulation under stress is an important topic of investigation. Two potential alternatives involve everyday occurrences of social processing and memory recall. Social support and past emotional experiences may help in guiding us toward appropriate neurophysiological responses through overlapping circuitry with stress and reward systems, while also buttressing cognitive regulation strategies by expanding one's perspective and allowing multiple opportunities to regulate retrospectively. In recognition that ongoing social and emotional events are often at the beginning of a cascade of both emotion regulation and memory processes, this chapter focuses on the emerging role of social relationships and autobiographical memory recall in regulating emotions under stress, highlighting opportunities and challenges associated with this process.

Cortisol awakening response prompts dynamic reconfiguration of brain networks in emotional and executive functioning

Emotion and cognition involve an intricate crosstalk of neural and endocrine systems that support dynamic reallocation of neural resources and optimal adaptation for upcoming challenges, an active process analogous to allostasis. As a hallmark of human endocrine activity, the cortisol awakening response (CAR) is recognized to play a critical role in proactively modulating emotional and executive functions. Yet, the underlying mechanisms of such proactive effects remain elusive. By leveraging pharmacological neuroimaging and hidden Markov modeling of brain state dynamics, we show that the CAR proactively modulates rapid spatiotemporal reconfigurations (state) of large-scale brain networks involved in emotional and executive functions. Behaviorally, suppression of CAR proactively impaired performance of emotional discrimination but not working memory (WM), while individuals with higher CAR exhibited better performance for both emotional and WM tasks. Neuronally, suppression of CAR led to a decrease in fractional occupancy and mean lifetime of task-related brain states dominant to emotional and WM processing. Further information-theoretic analyses on sequence complexity of state transitions revealed that a suppressed or lower CAR led to higher transition complexity among states primarily anchored in visual-sensory and salience networks during emotional task. Conversely, an opposite pattern of transition complexity was observed among states anchored in executive control and visuospatial networks during WM, indicating that CAR distinctly modulates neural resources allocated to emotional and WM processing. Our findings establish a causal link of CAR with brain network dynamics across emotional and executive functions, suggesting a neuroendocrine account for CAR proactive effects on human emotion and cognition.

Amygdala-Centered Emotional Processing in Prolonged Grief Disorder: Relationship With Clinical Symptomatology

BACKGROUND

Prolonged grief disorder (PGD) is a multidimensional condition with adverse health consequences. We hypothesized that enhanced negative emotional bias characterizes this disorder and underlies its key clinical symptoms.

METHODS

In a cross-sectional design, chronically grieving older adults (age 61.5 ± 8.9 years) experiencing probable PGD (n = 33) were compared with demographic- and time since loss-equated integrated (adaptive) grief participants (n = 38). To probe generalized negative affective reactivity, participants performed an emotional face-matching task during functional magnetic resonance imaging scanning and completed demographic and clinical assessments. Contrast maps (fearful + angry faces [-] shapes) were generated to determine group differences in brain activity within hypothesized affective and regulatory processing regions (amygdala, anterior insula, dorsal anterior cingulate, dorsolateral prefrontal cortex) and in exploratory whole-brain regression analyses.

RESULTS

The PGD group showed higher right amygdala activation to negative emotional stimuli than the integrated grief group (pcorrected < .05), which positively correlated with intrusive thoughts. Generalized psychophysiological interaction analysis revealed lower task-dependent functional connectivity (FC) between the right amygdala and posterior cingulate cortex/precuneus in PGD (pcorrected < .05), which negatively correlated with avoidance of loss reminders. Resting-state FC between the identified right amygdala and thalamus was higher in PGD (pcorrected < .05), which negatively correlated with loneliness.

CONCLUSIONS

Dysregulated amygdala-centric neural activity and FC during processing of negative affective stimuli and at rest appear to differentiate prolonged from integrated grief in older adults. Future investigations that use interventions to target amygdala-centric neural circuit abnormalities may provide new insights into the role of enhanced negative bias and related mechanisms that underlie PGD and support treatment efficacy.