Early Adolescence is a Critical Period for the Maturation of Inhibitory Behavior.

Psychiatric conditions marked by impairments in cognitive control often emerge during adolescence, when the prefrontal cortex (PFC) and its inputs undergo structural and functional maturation and are vulnerable to disruption by external events. It is not known, however, whether there exists a specific temporal window within the broad range of adolescence when the development of PFC circuitry and its related behaviors are sensitive to disruption. Here we show, in male mice, that repeated exposure to amphetamine during early adolescence leads to impaired behavioral inhibition, aberrant PFC dopamine connectivity, and reduced PFC dopamine function in adulthood. Remarkably, these deficits are not observed following exposure to the exact same amphetamine regimen at later times. These findings demonstrate that there is a critical period for the disruption of the adolescent maturation of cognitive control and PFC dopamine function and suggest that early adolescence is particularly relevant to the emergence of psychopathology in humans.

DCC-related developmental effects of abused- versus therapeutic-like amphetamine doses in adolescence.

The guidance cue receptor DCC controls mesocortical dopamine development in adolescence. Repeated exposure to an amphetamine regimen of 4 mg/kg during early adolescence induces, in male mice, downregulation of DCC expression in dopamine neurons by recruiting the Dcc microRNA repressor, microRNA-218 (miR-218). This adolescent amphetamine regimen also disrupts mesocortical dopamine connectivity and behavioral control in adulthood. Whether low doses of amphetamine in adolescence induce similar molecular and developmental effects needs to be established. Here, we quantified plasma amphetamine concentrations in early adolescent mice following a 4 or 0.5 mg/kg dose and found peak levels corresponding to those seen in humans following recreational and therapeutic settings, respectively. In contrast to the high doses, the low amphetamine regimen does not alter Dcc mRNA or miR-218 expression; instead, it upregulates DCC protein levels. Furthermore, high, but not low, drug doses downregulate the expression of the DCC receptor ligand, Netrin-1, in the nucleus accumbens and prefrontal cortex. Exposure to the low-dose regimen did not alter the expanse of mesocortical dopamine axons or their number/density of presynaptic sites in adulthood. Strikingly, adolescent exposure to the low-dose drug regimen does not impair behavioral inhibition in adulthood; instead, it induces an overall increase in performance in a go/no-go task. These results show that developmental consequences of exposure to therapeutic- versus abused-like doses of amphetamine in adolescence have dissimilar molecular signatures and opposite behavioral effects. These findings have important clinical relevance since amphetamines are widely used for therapeutic purposes in youth.

Self-injection of household cleaning detergents into a ventriculoperitoneal shunt reservoir during a suicide attempt: a case report and literature review.

Self-injection of household cleaning detergents (more specifically, commercial toilet bowl cleaner) into the reservoir of a ventriculoperitoneal shunt (VPS) has never been reported in the neurosurgical literature. A right-handed 41-year-old female with a past medical history significant for bipolar depression (with multiple prior hospital admissions for suicide attempts) and pseudotumor cerebri (status-post VPS placement from a right frontal approach) successfully injected ∼5 ml of toilet bowl cleaner into her ventricular shunt reservoir during a suicide attempt. She was found unresponsive by a family member 48 h after this event and presented to our hospital in moribund neurological condition (bilaterally fixed and dilated pupils with decerebrate posturing). Head computed tomography (CT) demonstrated marked ventriculomegaly. She was taken emergently to the operating room for placement of a left frontal ventriculostomy. Cerebrospinal fluid (CSF) sampled intraoperatively showed numerous Gram-positive cocci (later determined to be Staphylococcus epidermidis). For this reason, her right-sided shunt system was also removed in its entirety. She was treated with broad-spectrum intravenous and intraventricular antibiotics for her bacterial ventriculitis and her CSF was aggressively drained to treat her hydrocephalus. Once her infection had resolved, the shunt was replaced (using a right parietal approach) and she went on to make an excellent neurological recovery. Here, the authors present the case of a patient who self-injected household cleaning detergents into her VPS reservoir-and, likely, the ventricular system-during a suicide attempt and subsequently developed hydrocephalus and ventriculitis. Following this infrequent clinical scenario, consideration should be given to temporary ventriculostomy placement and shunt removal. Moreover, in patients with a known history of psychiatric co-morbidities-and particularly those patients with prior suicide attempts-the neurosurgeon should give serious consideration to placing the shunt system in an anatomical region which is difficult for the patient to self-access based upon their handedness.

Head Lag in Infancy: What Is It Telling Us?

OBJECTIVE: To investigate changes in head lag across postmenstrual age and define associations between head lag and (1) perinatal exposures and (2) neurodevelopment. METHOD: Sixty-four infants born ≤ 30 wk gestation had head lag assessed before and at term-equivalent age. Neurobehavior was assessed at term age. At 2 yr, neurodevelopmental testing was conducted. RESULTS: Head lag decreased with advancing postmenstrual age, but 58% (n = 37) of infants continued to demonstrate head lag at term. Head lag was associated with longer stay in the neonatal intensive care unit (p = .009), inotrope use (p = .04), sepsis (p = .02), longer endotracheal intubation (p = .01), and cerebral injury (p = .006). Head lag was related to alterations in early neurobehavior (p < .03), but no associations with neurodevelopment were found at 2 yr. CONCLUSION: Head lag was related to medical factors and early neurobehavior, but it may not be a good predictor of outcome when used in isolation.

Alterations in brain structure and neurodevelopmental outcome in preterm infants hospitalized in different neonatal intensive care unit environments.

OBJECTIVE: To evaluate associations between neonatal intensive care unit (NICU) room type (open ward and private room) and medical outcomes; neurobehavior, electrophysiology, and brain structure at hospital discharge; and developmental outcomes at 2 years of age. STUDY DESIGN: In this prospective longitudinal cohort study, we enrolled 136 preterm infants born <30 weeks gestation from an urban, 75-bed level III NICU from 2007-2010. Upon admission, each participant was assigned to a bedspace in an open ward or private room within the same hospital, based on space and staffing availability, where they remained for the duration of hospitalization. The primary outcome was developmental performance at 2 years of age (n = 86 infants returned for testing, which was 83% of survivors) measured using the Bayley Scales of Infant and Toddler Development, 3rd Edition. Secondary outcomes were: (1) medical factors throughout the hospitalization; (2) neurobehavior; and (3) cerebral injury and maturation (determined by magnetic resonance imaging and electroencephalography). RESULTS: At term equivalent age, infants in private rooms were characterized by a diminution of normal hemispheric asymmetry and a trend toward having lower amplitude integrated electroencephalography cerebral maturation scores (P = .02; ß = -0.52 [CI -0.95, -0.10]). At age 2 years, infants from private rooms had lower language scores (P = .006; ß = -8.3 [CI -14.2, -2.4]) and a trend toward lower motor scores (P = .02; ß = -6.3 [CI -11.7, -0.99]), which persisted after adjustment for potential confounders. CONCLUSION: These findings raise concerns that highlight the need for further research into the potential adverse effects of different amounts of sensory exposure in the NICU environment.

Altered regulation of sleep and feeding contributes to starvation resistance in Drosophila melanogaster.

Animals respond to changes in food availability by adjusting sleep and foraging strategies to optimize their fitness. Wild populations of the fruit fly, Drosophila melanogaster, display highly variable levels of starvation resistance that are dependent on geographic location, food availability and evolutionary history. How behaviors that include sleep and feeding vary in Drosophila with increased starvation resistance is unclear. We have generated starvation-resistant flies through experimental evolution to investigate the relationship between foraging behaviors and starvation resistance. Outbred populations of D. melanogaster were selected for starvation resistance over 60 generations. This selection process resulted in flies with a threefold increase in total lipids that survive up to 18 days without food. We tested starvation-selected (S) flies for sleep and feeding behaviors to determine the effect that selection for starvation resistance has had on foraging behavior. Flies from three replicated starvation-selected populations displayed a dramatic reduction in feeding and prolonged sleep duration compared to fed control (F) populations, suggesting that modified sleep and feeding may contribute to starvation resistance. A prolonged larval developmental period contributes to the elevated energy stores present in starvation-selected flies. By preventing S larvae from feeding longer than F larvae, we were able to reduce energy stores in adult S flies to the levels seen in adult F flies, thus allowing us to control for energy storage levels. However, the reduction of energy stores in S flies fails to generate normal sleep and feeding behavior seen in F flies with similar energy stores. These findings suggest that the behavioral changes observed in S flies are due to genetic regulation of behavior rather than elevated lipid levels. Testing S-F hybrid individuals for both feeding and sleep revealed a lack of correlation between food consumption and sleep duration, indicating further independence in genetic factors underlying the sleep and feeding changes observed in S flies. Taken together, these findings provide evidence that starvation selection results in prolonged sleep and reduced feeding through a mechanism that is independent of elevated energy stores. These findings suggest that changes in both metabolic function and behavior contribute to the increase in starvation resistance seen in flies selected for starvation resistance.

Cerebral maturation on amplitude-integrated electroencephalography and perinatal exposures in preterm infants.

AIM: To determine the associations between perinatal exposures, cerebral maturation on amplitude-integrated encephalography (aEEG) and outcome. METHODS: During this prospective cohort study, 136 infants ≤30 weeks estimated gestational age received 4 h of aEEG at four time points (between the first 2 weeks of life and term-equivalent age) during hospitalisation. Perinatal factors were documented. Associations between perinatal exposures and Burdjalov-scores were investigated. Neurodevelopmental outcome was assessed at the age of two. RESULTS: Immature cyclicity on the initial aEEG recording was associated with higher CRIB score (p = 0.01), vaginal delivery (p = 0.02), male gender (p < 0.01) and death (p = 0.01). Perinatal factors associated with lower Burdjalov-scores included cerebral injury (p < 0.01), sepsis (p < 0.01), lower caffeine dose (p = 0.006), prolonged mechanical ventilation (p = 0.002) and death (p < 0.01). Burdjalov-scores at 30 (ß = 2.62, p < 0.01) and 34 weeks postmenstrual age (ß = 2.89, p = 0.05) predicted motor scores. CONCLUSION: aEEG measures of cyclicity and Burdjalov-scores in the first 6 weeks of life, with an emphasis on 30 and 34 weeks postmenstrual age, demonstrated associations with perinatal factors known to predict adverse neurodevelopmental outcome.

Racial Health Disparity Associated With Poor Pediatric Cardiac Surgery Outcomes: A Multicentered, Cross-Sectional Study.

Background: Health disparities are known to play a role in pediatric cardiac surgery outcomes. Objectives: Risk factors associated with poor clinical outcomes were assessed. Methods: Using Pediatric Health Information System Database, pediatric subjects undergoing cardiac surgery using International Classification of Diseases 10th Revision from October 2015 to December 2020 were evaluated. Subjects were categorized by case complexity using the newly validated Risk Adjustment for Congenital Heart Surgery-2 (RACHS-2). Multivariable regression analyses were conducted to ascertain risk factors. Results: A total of 59,856 subjects, median age 7.4 months (IQR: 1.5-61 months) were included; 38,917 (low), 9,833 (medium), and 11,106 (high) RACHS-2. Overall, hospital mortality was 3% and postoperative length of stay (LOS) was 7 days (IQR: 4-18 days), with significant increases in both mortality and postoperative LOS from low to high RACHS-2 scores by multivariable analysis, Kaplan-Meier, and Cox regression. Mechanical ventilation, extracorporeal membrane oxygenation, infection, and surgical complication were most significantly associated with increased mortality by 1.198 to 10.227 times (P < 0.008). After controlling for these significant variables as well as RACHS-2, age at surgery and emergency/urgent admission type, multivariable analysis revealed that non-White race was associated with increased mortality (relative risk: 1.2, 95% CI: 0.729-0.955, P = 0.008) and increased postoperative LOS by 1.04 days (95% CI: 0.95-0.97, P < 0.001). This significant increase in both clinical outcomes was concordant in non-White neonates (mortality relative risk: 1.3, 95% CI: 1.1-1.6, P = 0.003; and postoperative LOS by 2.05 weeks (95% CI: 1.36-3.10, P < 0.001). Conclusions: The influence of racial differences in neonates and children should be further evaluated to mitigate any disparity in those undergoing cardiac surgery.

Neonatal nurses' and therapists' perceptions of positioning for preterm infants in the neonatal intensive care unit.

PURPOSE: Determine perceptions about positioning for preterm infants in the neonatal intensive care unit (NI CU). DESIGN: Twenty-item survey. SAMPLE: Neonatal nurses (n = 68) and speech, physical, and occupational therapists (n = 8). MAIN OUTCOME VARIABLE: Perceptions about positioning were obtained, and differences in perceptions between nurses and therapists were explored. RESULTS: Ninety-nine percent of respondents agreed that positioning is important for the well-being of the infant. Sixty-two percent of nurses and 86 percent of therapists identified the Dandle ROO as the ideal method of neonatal positioning. Forty-four percent of nurses and 57 percent of therapists reported that the Dandle ROO is the easiest positioning method to use in the NICU. Some perceptions differed: Therapists were more likely to report that the SleepSack does not hold the infant in good alignment. Nurses were more likely to report that the infant does not sleep well in traditional positioning.

Nursing Perceptions of Clinical Research in the Neonatal Intensive Care Unit.

PURPOSE: To determine perceptions of clinical research in the NICU. DESIGN: Survey study. SAMPLE: Nurses (n=68) employed in a level III NICU in the midwestern United States. MAIN OUTCOME VARIABLE: Cross-sectional analysis of responses to a survey exploring perceptions of clinical research. RESULTS: Ninety-seven percent of nurses (n=66) agree that clinical research is important for improving care, while 57% (n=39) report that it affects their day positively. Thirty-seven percent reported excellent communication between clinical and research teams. In addition, 27% (n=18) of nurses reported research presents complications for families, and 79% (n=54) reported that it is acceptable to cease a research protocol for infant benefit. Years of practice and whether nurses read research affected various responses. CONCLUSION: Clinical research is imperative to inform best practice, and nurses are an integral part of care. Therefore, it is essential to better define strategies to bridge the gap between clinical and research teams.

Impact of the gut microbiome on nicotine's motivational effects and glial cells in the ventral tegmental area in male mice.

A link between gut dysbiosis and the pathogenesis of brain disorders has been identified. A role for gut bacteria in drug reward and addiction has been suggested but very few studies have investigated their impact on brain and behavioral responses to addictive drugs so far. In particular, their influence on nicotine's addiction-like processes remains unknown. In addition, evidence shows that glial cells shape the neuronal activity of the mesolimbic system but their regulation, within this system, by the gut microbiome is not established. We demonstrate that a lack of gut microbiota in male mice potentiates the nicotine-induced activation of sub-regions of the mesolimbic system. We further show that gut microbiota depletion enhances the response to nicotine of dopaminergic neurons of the posterior ventral tegmental area (pVTA), and alters nicotine's rewarding and aversive effects in an intra-VTA self-administration procedure. These effects were not associated with gross behavioral alterations and the nicotine withdrawal syndrome was not impacted. We further show that depletion of the gut microbiome modulates the glial cells of the mesolimbic system. Notably, it increases the number of astrocytes selectively in the pVTA, and the expression of postsynaptic density protein 95 in both VTA sub-regions, without altering the density of the astrocytic glutamatergic transporter GLT1. Finally, we identify several sub-populations of microglia in the VTA that differ between its anterior and posterior sub-parts, and show that they are re-organized in conditions of gut microbiota depletion. The present study paves the way for refining our understanding of the pathophysiology of nicotine addiction.

Axo-glial interactions between midbrain dopamine neurons and oligodendrocyte lineage cells in the anterior corpus callosum.

Oligodendrocyte progenitor cells (OPCs) receive synaptic innervation from glutamatergic and GABAergic axons and can be dynamically regulated by neural activity, resulting in activity-dependent changes in patterns of axon myelination. However, it remains unclear to what extent other types of neurons may innervate OPCs. Here, we provide evidence implicating midbrain dopamine neurons in the innervation of oligodendrocyte lineage cells in the anterior corpus callosum and nearby white matter tracts of male and female adult mice. Dopaminergic axon terminals were identified in the corpus callosum of DAT-Cre mice after injection of an eYFP reporter virus into the midbrain. Furthermore, fast-scan cyclic voltammetry revealed monoaminergic transients in the anterior corpus callosum, consistent with the anatomical findings. Using RNAscope, we further demonstrate that ~ 40% of Olig2 + /Pdfgra + cells and ~ 20% of Olig2 + /Pdgfra- cells in the anterior corpus callosum express Drd1 and Drd2 transcripts. These results suggest that oligodendrocyte lineage cells may respond to dopamine released from midbrain dopamine axons, which could affect myelination. Together, this work broadens our understanding of neuron-glia interactions with important implications for myelin plasticity by identifying midbrain dopamine axons as a potential regulator of corpus callosal oligodendrocyte lineage cells.

Amphetamine disrupts dopamine axon growth in adolescence by a sex-specific mechanism in mice.

Initiating drug use during adolescence increases the risk of developing addiction or other psychopathologies later in life, with long-term outcomes varying according to sex and exact timing of use. The cellular and molecular underpinnings explaining this differential sensitivity to detrimental drug effects remain unexplained. The Netrin-1/DCC guidance cue system segregates cortical and limbic dopamine pathways in adolescence. Here we show that amphetamine, by dysregulating Netrin-1/DCC signaling, triggers ectopic growth of mesolimbic dopamine axons to the prefrontal cortex, only in early-adolescent male mice, underlying a male-specific vulnerability to enduring cognitive deficits. In adolescent females, compensatory changes in Netrin-1 protect against the deleterious consequences of amphetamine on dopamine connectivity and cognitive outcomes. Netrin-1/DCC signaling functions as a molecular switch which can be differentially regulated by the same drug experience as function of an individual's sex and adolescent age, and lead to divergent long-term outcomes associated with vulnerable or resilient phenotypes.

Social Determinants of Inter-Individual Variability and Vulnerability: The Role of Dopamine.

Individuals differ in their traits and preferences, which shape their interactions, their prospects for survival and their susceptibility to diseases. These correlations are well documented, yet the neurophysiological mechanisms underlying the emergence of distinct personalities and their relation to vulnerability to diseases are poorly understood. Social ties, in particular, are thought to be major modulators of personality traits and psychiatric vulnerability, yet the majority of neuroscience studies are performed on rodents in socially impoverished conditions. Rodent micro-society paradigms are therefore key experimental paradigms to understand how social life generates diversity by shaping individual traits. Dopamine circuitry is implicated at the interface between social life experiences, the expression of essential traits, and the emergence of pathologies, thus proving a possible mechanism to link these three concepts at a neuromodulatory level. Evaluating inter-individual variability in automated social testing environments shows great promise for improving our understanding of the link between social life, personality, and precision psychiatry - as well as elucidating the underlying neurophysiological mechanisms.

Mature human eosinophils express functional Notch ligands mediating eosinophil autocrine regulation.

Eosinophil chemotaxis and survival within tissues are key components in the development of tissue eosinophilia and subsequent effector responses. In this study, we demonstrate a novel mechanism of eosinophil autoregulation affecting migration and survival mediated through Notch signaling. We show for the first time that human blood eosinophils express Notch receptors and Notch ligands, expressions of which are influenced by the presence of eosinophil-activating granulocyte-macrophage colony-stimulating factor (GM-CSF). Evidence of Notch receptor activation and subsequent transcription of the Notch-responsive gene HES1 were observed in GM-CSF-stimulated eosinophils, confirming functionality of eosinophil-expressed Notch-signaling components. Moreover, by inhibiting Notch signaling with gamma-secretase inhibitors or Notch receptor-specific neutralizing antibodies, we demonstrate that autocrine Notch signaling enhances stimulus-mediated actin rearrangement and eosinophil chemokinesis, and impairs eosinophil viability. Taken together, these data suggest autocrine Notch signaling, enhanced in response to tissue- or inflammatory-derived signals, influences eosinophil activity and longevity, which may ultimately contribute to the development of tissue eosinophilia and exacerbation or remediation of eosinophil effector functions.

Eosinophil granules function extracellularly as receptor-mediated secretory organelles.

Intracellular granules in several types of leukocytes contain preformed proteins whose secretions contribute to immune and inflammatory functions of leukocytes, including eosinophils, cells notably associated with asthma, allergic inflammation, and helminthic infections. Cytokines and chemokines typically elicit extracellular secretion of granule proteins by engaging receptors expressed externally on the plasma membranes of cells, including eosinophils. Eosinophil granules, in addition to being intracellular organelles, are found as intact membrane-bound structures extracellularly in tissue sites of eosinophil-associated diseases. Neither the secretory capacities of cell-free eosinophil granules nor the presence of functional cytokine and chemokine receptors on membranes of leukocyte granules have been recognized. Here, we show that granules of human eosinophils express membrane receptors for a cytokine, IFN-gamma, and G protein-coupled membrane receptors for a chemokine, eotaxin, and that these receptors function by activating signal-transducing pathways within granules to elicit secretion from within granules. Capacities of intracellular granule organelles to function autonomously outside of eosinophils as independent, ligand-responsive, secretion-competent structures constitute a novel postcytolytic mechanism for regulated secretion of eosinophil granule proteins that may contribute to eosinophil-mediated inflammation and immunomodulation.

Mesocorticolimbic Dopamine Pathways Across Adolescence: Diversity in Development.

Mesocorticolimbic dopamine circuity undergoes a protracted maturation during adolescent life. Stable adult levels of behavioral functioning in reward, motivational, and cognitive domains are established as these pathways are refined, however, their extended developmental window also leaves them vulnerable to perturbation by environmental factors. In this review, we highlight recent advances in understanding the mechanisms underlying dopamine pathway development in the adolescent brain, and how the environment influences these processes to establish or disrupt neurocircuit diversity. We further integrate these recent studies into the larger historical framework of anatomical and neurochemical changes occurring during adolescence in the mesocorticolimbic dopamine system. While dopamine neuron heterogeneity is increasingly appreciated at molecular, physiological, and anatomical levels, we suggest that a developmental facet may play a key role in establishing vulnerability or resilience to environmental stimuli and experience in distinct dopamine circuits, shifting the balance between healthy brain development and susceptibility to psychiatric disease.

Chronic nicotine increases midbrain dopamine neuron activity and biases individual strategies towards reduced exploration in mice.

Long-term exposure to nicotine alters brain circuits and induces profound changes in decision-making strategies, affecting behaviors both related and unrelated to drug seeking and consumption. Using an intracranial self-stimulation reward-based foraging task, we investigated in mice the impact of chronic nicotine on midbrain dopamine neuron activity and its consequence on the trade-off between exploitation and exploration. Model-based and archetypal analysis revealed substantial inter-individual variability in decision-making strategies, with mice passively exposed to nicotine shifting toward a more exploitative profile compared to non-exposed animals. We then mimicked the effect of chronic nicotine on the tonic activity of dopamine neurons using optogenetics, and found that photo-stimulated mice adopted a behavioral phenotype similar to that of mice exposed to chronic nicotine. Our results reveal a key role of tonic midbrain dopamine in the exploration/exploitation trade-off and highlight a potential mechanism by which nicotine affects the exploration/exploitation balance and decision-making.

Nicotine inhibits the VTA-to-amygdala dopamine pathway to promote anxiety.

Nicotine stimulates dopamine (DA) neurons of the ventral tegmental area (VTA) to establish and maintain reinforcement. Nicotine also induces anxiety through an as yet unknown circuitry. We found that nicotine injection drives opposite functional responses of two distinct populations of VTA DA neurons with anatomically segregated projections: it activates neurons that project to the nucleus accumbens (NAc), whereas it inhibits neurons that project to the amygdala nuclei (Amg). We further show that nicotine mediates anxiety-like behavior by acting on ß2-subunit-containing nicotinic acetylcholine receptors of the VTA. Finally, using optogenetics, we bidirectionally manipulate the VTA-NAc and VTA-Amg pathways to dissociate their contributions to anxiety-like behavior. We show that inhibition of VTA-Amg DA neurons mediates anxiety-like behavior, while their activation prevents the anxiogenic effects of nicotine. These distinct subpopulations of VTA DA neurons with opposite responses to nicotine may differentially drive the anxiogenic and the reinforcing effects of nicotine.