Chronic stress, cortical plasticity and neuroecology

Econeurobiology and brain development in children: key factors affecting development, behavioral outcomes, and school interventions

The Econeurobiology of the brain describes the environment in which an individual's brain develops. This paper explores the complex neural mechanisms that support and evaluate enrichment at various stages of development, providing an overview of how they contribute to plasticity and enhancement of both achievement and health. It explores the deep benefits of enrichment and contrasts them with the negative effects of trauma and stress on brain development. In addition, the paper strongly emphasizes the integration of Gardner's intelligence types into the school curriculum environment. It emphasizes the importance of linking various intelligence traits to educational strategies to ensure a holistic approach to cognitive development. In the field of Econeurobiology, this work explains the central role of the environment in shaping the development of the brain. It examines brain connections and plasticity and reveals the impact of certain environmental factors on brain development in early and mid-childhood. In particular, the six key factors highlighted are an environment of support, nutrition, physical activity, music, sleep, and cognitive strategies, highlighting their potential to improve cognitive abilities, memory, learning, self-regulation, and social and emotional development. This paper also investigates the social determinants of health and education in the context of Econeurobiology. It emphasizes the transformative power of education in society, especially in vulnerable communities facing global challenges in accessing quality education.

Randomized controlled trials of non-pharmacological interventions for healthy seniors: Effects on cognitive decline, brain plasticity and activities of daily living-A 23-year scoping review

Little is known about the simultaneous effects of non-pharmacological interventions (NPI) on healthy older adults' behavior and brain plasticity, as measured by psychometric instruments and magnetic resonance imaging (MRI). The purpose of this scoping review was to compile an extensive list of randomized controlled trials published from January 1, 2000, to August 31, 2023, of NPI for mitigating and countervailing age-related physical and cognitive decline and associated cerebral degeneration in healthy elderly populations with a mean age of 55 and over. After inventorying the NPI that met our criteria, we divided them into six classes: single-domain cognitive, multi-domain cognitive, physical aerobic, physical non-aerobic, combined cognitive and physical aerobic, and combined cognitive and physical non-aerobic. The ultimate purpose of these NPI was to enhance individual autonomy and well-being by bolstering functional capacity that might transfer to activities of daily living. The insights from this study can be a starting point for new research and inform social, public health, and economic policies. The PRISMA extension for scoping reviews (PRISMA-ScR) checklist served as the framework for this scoping review, which includes 70 studies. Results indicate that medium- and long-term interventions combining non-aerobic physical exercise and multi-domain cognitive interventions best stimulate neuroplasticity and protect against age-related decline and that outcomes may transfer to activities of daily living.

Introducing the Neuroplastic Narrative: a non-pathologizing biological foundation for trauma-informed and adverse childhood experience aware approaches

Most people accessing mental health services have adverse childhood experiences (ACEs) and/or histories of complex trauma. In recognition of this, there are calls to move away from medical model approaches and move toward trauma-informed approaches which privilege the impact of life experience over underlying pathology in the etiology of emotional and psychological suffering. Trauma-informed approaches lack a biological narrative linking trauma and adversity to later suffering. In its absence, this suffering is diagnosed and treated as a mental illness. This study articulates the Neuroplastic Narrative, a neuroecological theory that fills this gap, conceptualizing emotional and psychological suffering as the cost of surviving and adapting to the impinging environments of trauma and adversity. The Neuroplastic Narrative privileges lived experience and recognizes that our experiences become embedded in our biology through evolved mechanisms that ultimately act to preserve survival in the service of reproduction. Neuroplasticity refers to the capacity of neural systems to adapt and change. Our many evolved neuroplastic mechanisms including epigenetics, neurogenesis, synaptic plasticity, and white matter plasticity allow us to learn from, and adapt to, past experiences. This learning and adaption in turn allows us to better anticipate and physiologically prepare for future experiences that (nature assumes) are likely to occur, based on past experiences. However, neuroplastic mechanisms cannot discriminate between experiences; they function to embed experience regardless of the quality of that experience, generating vicious or virtuous cycles of psychobiological anticipation, to help us survive or thrive in futures that resemble our privileged or traumatic pasts. The etiology of suffering that arises from this process is not a pathology (a healthy brain is a brain that can adapt to experience) but is the evolutionary cost of surviving traumatizing environments. Misidentifying this suffering as a pathology and responding with diagnosis and medication is not trauma-informed and may cause iatrogenic harm, in part through perpetuating stigma and exacerbating the shame which attends complex trauma and ACEs. As an alternative, this study introduces the Neuroplastic Narrative, which is situated within an evolutionary framework. The Neuroplastic Narrative complements both Life History and Attachment Theory and provides a non-pathologizing, biological foundation for trauma-informed and Adverse Childhood Experience aware approaches.

Bioinformatics Analysis of Molecular Interactions between Endoplasmic Reticulum Stress and Ferroptosis under Stress Exposure

Stress has become a universal biological phenomenon in the body, which leads to pathophysiological changes. However, the molecular network interactions between endoplasmic reticulum (ER) stress and ferroptosis under stressful conditions are not clear. For this purpose, we screened the gene expression profile of GSE173795 for intersection with ferroptosis genes and screened 68 differentially expressed genes (DEGs) (63 up-regulated, 5 down-regulated), mainly related to lipid and atherosclerosis, autophagy-animal, mitophagy-animal, focal adhesion, DNA replication, proteasome, oocyte meiosis, toll-like receptor signaling pathway, cell cycle, etc. Immune infiltration analysis revealed that stress resulted in decreased B cells memory, T cells CD8 and T cells CD4 memory resting, monocytes, macrophages M2, and increased B cells naive, T cells follicular helper, and macrophages M1. 19 core-DEGs (ASNS, TRIB3, ATF4, EIF2S1, CEBPG, RELA, HSPA5, DDIT3, STAT3, MAP3K5, HIF1A, HNF4A, MAPK14, HMOX1, CDKN1A, KRAS, SP1, SIRT1, EGFR) were screened, all of which were up-regulated DEGs. These biological processes and pathways were mainly involved in responding to ER stress, lipid and atherosclerosis, cellular response to stress, cellular response to chemical stress, and regulation of DNA-templated transcription in response to stress, etc. Spearman analysis did not find MAPK14 to be significantly associated with immune cells. Other core-DEGs were associated with immune cells, including B cells naive, T cells follicular helper, and monocytes. Based on core-DEGs, 283 miRNAs were predicted. Among the 22 miRNAs with highly cross-linked DEGs, 11 had upstream lncRNA, mainly targeting STAT3, SP1, CDKN1A, and SIRT1, and a total of 39 lncRNA were obtained. 85 potential drugs targeting 11 core-DEGs were identified and were expected to be potential immunotherapeutic agents for stress injury. Our experiments also confirmed that Liproxstatin-1 alleviates common cross-linked proteins between ER stress and ferroptosis. In conclusion, our study explored the molecular mechanisms and network interactions among stress-ER stress-ferroptosis from a novel perspective, which provides new research ideas for studying stressful injury.

Glucocorticoid Regulates the Synthesis of Porcine Muscle Protein through m6A Modified Amino Acid Transporter SLC7A7

The occurrence of stress is unavoidable in the process of livestock production, and prolonged stress will cause the decrease of livestock productivity. The stress response is mainly regulated by the hypothalamic-pituitary-adrenal axis (HPA axis), which produces a large amount of stress hormones, namely glucocorticoids (GCs), and generates a severe impact on the energy metabolism of the animal body. It is reported that m⁶A modification plays an important role in the regulation of stress response and also participates in the process of muscle growth and development. In this study, we explored the effect of GCs on the protein synthesis procession of porcine skeletal muscle cells (PSCs). We prove that dexamethasone affects the expression of SLC7A7, a main amino acid transporter for protein synthesis by affecting the level of m⁶A modification in PSCs. In addition, we find that SLC7A7 affects the level of PSC protein synthesis by regulating the conduction of the mTOR signaling pathway, which indicates that the reduction of SLC7A7 expression may alleviate the level of protein synthesis under stress conditions.

Plasma metabolites associated with physiological and biochemical indexes indicate the effect of caging stress on mallard ducks (Anas platyrhynchos)

Objective

Cage rearing has critical implications for the laying duck industry because it is convenient for feeding and management. However, caging stress is a type of chronic stress that induces maladaptation. Environmental stress responses have been extensively studied, but no detailed information is available about the comprehensive changes in plasma metabolites at different stages of caging stress in ducks. We designed this experiment to analyze the effects of caging stress on performance parameters and oxidative stress indexes in ducks.

Methods

Liquid chromatography tandem mass spectrometry (LC/MS-MS) was used to determine the changes in metabolites in duck plasma at 5 (CR5), 10 (CR10), and 15 (CR15) days after cage rearing and traditional breeding (TB). The associated pathways of differentially altered metabolites were analyzed using Kyoto encyclopedia of genes and genomes (KEGG) database.

Results

The results of this study indicate that caging stress decreased performance parameters, and the plasma total superoxide dismutase levels were increased in the CR10 group compared with the other groups. In addition, 1,431 metabolites were detected. Compared with the TB group, 134, 381, and 190 differentially produced metabolites were identified in the CR5, CR10, and CR15 groups, respectively. The results of principal component analysis (PCA) show that the selected components sufficiently distinguish the TB group and CR10 group. KEGG analysis results revealed that the differentially altered metabolites in duck plasma from the CR5 and TB groups were mainly associated with ovarian steroidogenesis, biosynthesis of unsaturated fatty acids, and phenylalanine metabolism.

Conclusion

In this study, the production performance, blood indexes, number of metabolites and PCA were compared to determine effect of the caging stress stage on ducks. We inferred from the experimental results that caging-stressed ducks were in the sensitive phase in the first 5 days after caging, caging for approximately 10 days was an important transition phase, and then the duck continually adapted.

Microglia react to partner loss in a sex- and brain site-specific manner in prairie voles

Positive social relationships are paramount for the survival of mammals and beneficial for mental and physical health, buffer against stressors, and even promote appropriate immune system functioning. By contrast, impaired social relationships, social isolation, or the loss of a bonded partner lead to aggravated physical and mental health. For example, in humans partner loss is detrimental for the functioning of the immune system and heightens the susceptibility for the development of post-traumatic stress disorders, anxiety disorders, and major depressive disorders. To understand potential underlying mechanisms, the monogamous prairie vole can provide important insights. In the present study, we separated pair bonded male and female prairie voles after five days of co-housing, subjected them to the forced swim test on the fourth day following separation, and studied their microglia morphology and activation in specific brain regions. Partner loss increased passive stress-coping in male, but not female, prairie voles. Moreover, partner loss was associated with microglial priming within the parvocellular region of the paraventricular nucleus of the hypothalamus (PVN) in male prairie voles, whereas in female prairie voles the morphological activation within the whole PVN and the prelimbic cortex (PrL) was decreased, marked by a shift towards ramified microglial morphology. Expression of the immediate early protein c-Fos following partner loss was changed within the PrL of male, but not female, prairie voles. However, the loss of a partner did not affect the investigated aspects of the peripheral immune response. These data suggest a potential sex-dependent mechanism for the regulation of microglial activity following the loss of a partner, which might contribute to the observed differences in passive stress-coping. This study furthers our understanding of the effects of partner loss and its short-term impact on the CNS as well as the CNS immune system and the peripheral innate immune system in both male and female prairie voles.

Dream Recall/Affect and the Hypothalamic-Pituitary-Adrenal Axis

In this concise review, we present an overview of research on dream recall/affect and of the hypothalamic–pituitary–adrenal (HPA) axis, discussing caveats regarding the action of hormones of the HPA axis (mainly cortisol and its free form, cortisol-binding globulin and glucocorticoid receptors). We present results of studies regarding dream recall/affect and the HPA axis under physiological (such as waking) or pathological conditions (such as in Cushing’s syndrome or stressful situations). Finally, we try to integrate the effect of the current COVID-19 situation with dream recall/affect vis-à-vis the HPA axis.

The efficacy of repetitive transcranial magnetic stimulation (rTMS) for young individuals with high-level perceived stress: study protocol for a randomized sham-controlled trial

Background

High level of perceived stress may result in negative effects both psychologically and physically on individuals and may predispose onset of mental disorders such as depression, anxiety, and posttraumatic stress disorder. However, there is no suitable intervention for it. Repetitive transcranial magnetic stimulation (rTMS) studies have shown its therapeutic efficacy in treatment resistant patients with stress-related disorders. Here we describe an exploratory study protocol to investigate the effect of the intervention for the individuals with high level of stress.

Method

This is a single blinded, randomized sham-controlled trial, targeting at young healthy adults aging from 18 to 24 years old. Forty eligible volunteers will be recruited and randomly divided into active and sham rTMS group. All subjects will take a set of neuropsychological and biological assessments and MRI scanning before and right after the intervention. During the interventional period, 12-session stimulations will be performed in 4 weeks with three sessions per week. The primary outcome will detect the difference of Chinese 14-item perceived stress scales between active and sham rTMS groups after intervention. Secondary outcomes will examine the differences of other affective measurements, level of cortisol, and MRI-derived neural functional measures between the two groups after intervention.

Discussion

This trial aims to examine the effect of the 12-session rTMS intervention on individuals with high level of perceived stress. Positive or negative findings from any of the outcome measures would further our understanding of the efficacy of the stimulation and its neural impact. If effective, it would provide an evidence for a new treatment for high perceived stress.

Trial registration

Chinese Clinical Trial Registry (ChiCTR1900027662). Registered on 23 November 2019. And all items of the WHO Trial Registry Data set can be found within the protocol.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05308-3.

How stress physically re-shapes the brain: Impact on brain cell shapes, numbers and connections in psychiatric disorders

Severe stress is among the most robust risk factors for the development of psychiatric disorders. Imaging studies indicate that life stress is integral to shaping the human brain, especially regions involved in processing the stress response. Although this is likely underpinned by changes to the cytoarchitecture of cellular networks in the brain, we are yet to clearly understand how these define a role for stress in human psychopathology. In this review, we consolidate evidence of macro-structural morphometric changes and the cellular mechanisms that likely underlie them. Focusing on stress-sensitive regions of the brain, we illustrate how stress throughout life may lead to persistent remodelling of the both neurons and glia in cellular networks and how these may lead to psychopathology. We support that greater translation of cellular alterations to human cohorts will support parsing the psychological sequalae of severe stress and improve our understanding of how stress shapes the human brain. This will remain a critical step for improving treatment interventions and prevention outcomes.

Pathways from early adversity to later adjustment: Tests of the additive and bidirectional effects of executive control and diurnal cortisol in early childhood

Additive and bidirectional effects of executive control and hypothalamic-pituitary-adrenal (HPA) axis regulation on children's adjustment were examined, along with the effects of low income and cumulative risk on executive control and the HPA axis. The study utilized longitudinal data from a community sample of preschool age children (N = 306, 36-39 months at Time 1) whose families were recruited to overrepresent low-income contexts. We tested the effects of low income and cumulative risk on levels and growth of executive control and HPA axis regulation (diurnal cortisol level), the bidirectional effects of executive control and the HPA axis on each other, and their additive effects on children's adjustment problems, social competence and academic readiness. Low income predicted lower Time 4 executive control, and cumulative risk predicted lower Time 4 diurnal cortisol level. There was little evidence of bidirectional effects of executive control and diurnal cortisol. However, both executive control and diurnal cortisol predicted Time 4 adjustment, suggesting additive effects. There were indirect effects of income on all three adjustment outcomes through executive control, and of cumulative risk on adjustment problems and social competence through diurnal cortisol. The results provide evidence that executive control and diurnal cortisol additively predict children's adjustment and partially account for the effects of income and cumulative risk on adjustment.

Unexpected inflammation in the sympathetic ganglia in thromboangiitis obliterans: more likely sterile or infectious induced inflammation?

Introduction

The aim of this study was to determine if the inflammation of the sympathetic ganglia (SG) in thromboangiitis obliterans (TAO) is induced by an infectious pathogen inside or if it is a reactive sterile inflammation.

Methods

For the purpose of this study, the gene expression of high-mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), toll-like receptor 9 (TLR9), and the receptor for advanced glycation end-products (RAGE) were evaluated on the complementary DNA (cDNA) of the SG tissues of 24 TAO patients and two controls with hyperhidrosis by real-time polymerase chain reaction (PCR) and analysed by the Pfaffl method.

Results

The gene expression of HMGB1 and TLR9 increased by about 25- and 2-fold changes in the SG of the TAO patients, respectively. However, there was no change in the gene expression of TLR4 or RAGE.

Conclusion

It appears that the inflammation in the SG of TAO patients is more likely a sterile inflammation, and its trigger may be mitochondrial DNA (mtDNA). Cadmium in cigarettes could be responsible for the induction of mtDNA release to the cell cytoplasm. In addition, the high expression of HMGB1 may play a role in the pathogenesis of TAO and may be responsible for both clinical manifestation of the disease and the imaging findings. Moreover, HMGB1 may be a target for treatment protocols for TAO. Further studies are highly recommended.

Endoplasmic Reticulum Stress Is Involved in Stress-Induced Hypothalamic Neuronal Injury in Rats via the PERK-ATF4-CHOP and IRE1-ASK1-JNK Pathways

Objective

As a high-level nerve center that regulates visceral and endocrine activity, the hypothalamus plays an important role in regulating the body’s stress response. Previous studies have shown that stress can cause damage to hypothalamic neurons. The present study aimed to further clarify the mechanism of endoplasmic reticulum stress (ERS) involvement in hypothalamic neuronal injury.

Methods

A 7-day stressed rat model was established with daily restraining for 8 h and forced ice-water swimming for 5 min. The rats were randomly divided into control, stress, stress + GSK2606414 (PERK phosphorylation inhibitor), stress + KIRA6 (IRE1 phosphokinase activity inhibitor), GSK2606414, and KIRA6 groups. The pathological changes of hypothalamic neurons were observed by thionine staining. Expression of ERS proteins GRP78, ATF4, ASK1, JNK, and CHOP in the hypothalamic neurons were observed by immunohistochemical staining. The expression of JNK and CHOP mRNA in the hypothalamic neurons were observed by RNA in situ hybridization (RNA Scope) and the expression of related proteins and mRNA was semiquantitatively analyzed by microscopy-based multicolor tissue cytometry (MMTC).

Results

Thionine staining revealed that stress exposure resulted in edema, a lack of Nissl bodies, and pyknosis in hypothalamic neurons. Immunohistochemistry and RNA Scope showed that stress exposure significantly increased the expression of GRP78, ATF4, ASK1, CHOP, JNK, JNK mRNA, and CHOP mRNA. Treatment with PERK and IRE1 inhibitors attenuated pathological damage and downregulated the expression of ATF4, ASK1, JNK, CHOP, JNK mRNA, and CHOP mRNA.

Conclusion

Stress caused pathological changes in rat hypothalamic neurons. ERS PERK-ATF4-CHOP and IRE1-ASK1-JNK pathways were involved in the injury process.

Investigation on the association of occupational stress with risk of polycystic ovary syndrome and mediating effects of HOMA-IR

We aimed to evaluate the association between occupational stress and PCOS risk in a Chinese population and whether insulin resistance mediates the association. A total of 366 patients with PCOS and 325 controls were included in this study. Three logistic regression analyzes were applied in statistical analysis. In the first logistic regression analysis, the occupational stress significantly influenced development of PCOS (cumulative R² = 0.737). In model 2, the environmental factors cumulatively accounted for 4.2% of the variance in PCOS risk. In model 3, which contained HOMA-IR, the R² of HOMA-IR to PCOS risk was as high as 0.41, but the R² of occupational stress reduced to 0.22. HOMA-IR became the main risk factor for PCOS. SEM model showed that ORQ, PSQ and PRQ had a direct and indirect effect on PCOS, and the indirect effect was through HOMA-IR. Occupational stress has a direct and indirect relationship with PCOS, which is mediated by HOMA-IR.

Antidepressant Effect of Fraxinus rhynchophylla Hance Extract in a Mouse Model of Chronic Stress-Induced Depression

Prolonged exposure to stress can affect mood and cognition and lead to mood disorders. Research on stress-associated mood disorders is important in modern society as people are increasingly exposed to unavoidable stressors. We used a mouse model with 2 weeks of exposure to electric foot shock and restraint, to determine the effect of Fraxinus rhynchophylla Hance (FX) extract on chronic stress-induced depression. We measured the effect of FX extract using various physiological, behavioral, and biochemical measures. FX extract ameliorated chronic stress-induced body and relative liver weight loss and improved depressive-like behaviors in the open field and forced swim tests. In addition, plasma cortisol and serotonin levels in stress-induced mice following FX treatment were similar to normal mice, and the elevation of proinflammatory cytokines was prevented. Moreover, FX treatment increased the expression of phosphorylated cyclic adenosine-3′,5′-monophosphate response element-binding protein (pCREB)/brain-derived neurotrophic factor (BDNF). Further experiments confirmed the efficacy of FX extract by showing similar results using esculin and esculetin, compounds extracted from FX. Taken together, these results indicate that FX extract has an antidepressant effect on chronic stress-induced depression by associating signaling with neuroinflammation and neurogenesis.

Behavioral and structural adaptations to stress

Unpredictable aversive experiences, or stressors, lead to changes in depression- and anxiety-related behavior and to changes in hippocampal structure including decreases in adult neurogenesis, granule cell and pyramidal cell dendritic morphology, and volume. Here we review the relationship between these behavioral and structural changes and discuss the possibility that these changes may be largely adaptive. Specifically, we suggest that new neurons in the dentate gyrus enhance behavioral adaptability to changes in the environment, biasing behavior in novel situations based on previous experience with stress. Conversely, atrophy-like changes in the hippocampus and decreased adult neurogenesis following chronic stress may serve to limit stress responses and stabilize behavior during chronic stress.

The Energy Costs of Prematurity and the Neonatal Intensive Care Unit (NICU) Experience

Premature neonates are in an energy deficient state due to (1) oxygen desaturation and hypoxia events, (2) painful and stressful stimuli, (3) illness, and (4) neurodevelopmental energy requirements. Failure to correct energy deficiency in premature infants may lead to adverse effects such as neurodevelopmental delay and negative long-term metabolic and cardiovascular outcomes. The effects of energy dysregulation and the challenges that clinicians in the Neonatal Intensive Care Unit (NICU) face in meeting the premature infant's metabolic demands are discussed. Specifically, the focus is on the effects of pain and stress on energy homeostasis. Energy deficiency is a complex problem and requires a multi-faceted solution to promote optimum development of premature infants.

Medical Yoga Therapy

Medical yoga is defined as the use of yoga practices for the prevention and treatment of medical conditions. Beyond the physical elements of yoga, which are important and effective for strengthening the body, medical yoga also incorporates appropriate breathing techniques, mindfulness, and meditation in order to achieve the maximum benefits. Multiple studies have shown that yoga can positively impact the body in many ways, including helping to regulate blood glucose levels, improve musculoskeletal ailments and keeping the cardiovascular system in tune. It also has been shown to have important psychological benefits, as the practice of yoga can help to increase mental energy and positive feelings, and decrease negative feelings of aggressiveness, depression and anxiety.

Tourette syndrome in the context of evolution and behavioral ecology

Tourette syndrome, and the closely related spectrum of tic disorders, are inherited neuropsychiatric conditions characterized by the presence of repetitive and stereotyped movements. Tics are elicited by either environmental experiences or internal signals that instruct the basal ganglia to initiate automatic or procedural movements. In most vertebrates the basal ganglia encode instructions for habitually used sequences of motor movements that are essential to survival. Tic disorders may represent evolved phenotypes with a lower threshold for basal ganglia-directed actions. This may have produced a susceptibility to extraneous tics, but also produced fast-acting tactical solutions to immediate physical problems. During periods of nonstop movement, continual foraging, and sustained vigilance, it may have been advantageous to allow subcortical motor commands to intrude into ongoing motor activities. It is clear that the engrams for individual motor responses held in the basal ganglia are selected by converging cortical and subcortical inputs. This form of convergent action selection results in the selection of the most contextually reinforced actions. Today people with Tourette's have tics that seem arbitrary and inappropriate; however, this may be due to the vast discrepancies in reinforcement between the ancestral environment and the modern one. In prehistoric environments, the motor behaviors of individuals with tic disorders may have been appropriate in environmental context, and had ecological relevance in survival and self-promotion.

Incremental change in the set of coactive cortical assemblies enables mental continuity

This opinion article explores how sustained neural firing in association areas allows high-order mental representations to be coactivated over multiple perception-action cycles, permitting sequential mental states to share overlapping content and thus be recursively interrelated. The term "state-spanning coactivity" (SSC) is introduced to refer to neural nodes that remain coactive as a group over a given period of time. SSC ensures that contextual groupings of goal or motor-relevant representations will demonstrate continuous activity over a delay period. It also allows potentially related representations to accumulate and coactivate despite delays between their initial appearances. The nodes that demonstrate SSC are a subset of the active representations from the previous state, and can act as referents to which newly introduced representations of succeeding states relate. Coactive nodes pool their spreading activity, converging on and activating new nodes, adding these to the remaining nodes from the previous state. Thus, the overall distribution of coactive nodes in cortical networks evolves gradually during contextual updating. The term "incremental change in state-spanning coactivity" (icSSC) is introduced to refer to this gradual evolution. Because a number of associated representations can be sustained continuously, each brain state is embedded recursively in the previous state, amounting to an iterative process that can implement learned algorithms to progress toward a complex result. The longer representations are sustained, the more successive mental states can share related content, exhibit progressive qualities, implement complex algorithms, and carry thematic or narrative continuity. Included is a discussion of the implications that SSC and icSSC may have for understanding working memory, defining consciousness, and constructing AI architectures.