Functional connectomes (FCs) derived from fMRI are unique to an individual and can be reliably distinguished from those of others. However, the neurobiological basis for this "fingerprint"-like uniqueness remains unclear. One hypothesis holds that FC fingerprinting reflects idiosyncratic conscious experiences, while an alternative suggests that stable, intrinsic brain functional network structure underpins individual specificity. To test these hypotheses, we analyzed FC fingerprints across sleep stages using a two-night concurrent EEG-fMRI dataset from healthy participants and exploited the natural fluctuations in consciousness that occur across the sleep-wake cycle: during sleep, consciousness gradually diminishes from N1 to N3 non-REM (NREM) sleep, then partially reemerges during REM sleep. Contrary to the consciousness-dependent hypothesis, we found that FC fingerprinting remained robust, and in fact improved during deep, unconscious sleep (N3) relative to wakefulness. Moreover, the brain networks contributing most to individual identification shifted across sleep stages, with hippocampal connectivity playing a larger role during N3. Finally, using a deep-learning classifier (multi-layer perceptron) on short (90 seconds) fMRI segments, we demonstrated high identification accuracy; notably, models trained on deep-sleep data generalized well across all stages, including wakefulness. These findings favor the view that individual-specific network architecture rather than moment-to-moment conscious experience underlies FC fingerprints, with important implications for their use as biomarkers in both healthy and clinical populations.

Rapid Eye Movement (REM) sleep, characterized by vivid dreaming and muscle atonia, raises the fascinating question about how such immersive experiences occur without external sensory input. To investigate this, we analyzed data from a whole-night 8-hour EEG-fMRI concurrent recording study with 12 non-sleep-deprived participants. Our findings confirmed that during REM sleep, all thalamic subnetworks simultaneously connect with multiple sensory networks, including visual, motor, auditory, and action-planning networks, which was not observed during wake. Additionally, intra-thalamic connection was significantly higher during REM sleep compared to wake in all 11 participants with high-quality fMRI data during REM, and compared to Non-REM stages in nine out of 11 participants. We validated these results on seven participants who achieved REM sleep on the first (adaptation) night. Building on these findings, we further hypothesized that the observed increases in thalamus-related FCs were specifically linked to phasic REM, a state associated with vivid dreaming, as opposed to tonic REM. Using the Hidden Markov Model to classify phasic and tonic REM states, we found that phasic REM exhibited significantly greater intra-thalamic and thalamo-cortical FCs than tonic REM. These results suggest that during REM sleep, specifically during phasic REM, thalamic subnetworks function collectively to distribute internally generated sensory information to sensory-related cortical networks, which might be the neural mechanisms underlying vivid dreaming.

Background:Adolescence is a critical period of brain maturation and heightened vulnerability to cognitive and mental health disorders. Sleep plays a vital role in neurodevelopment, yet the mechanisms linking insufficient sleep to adverse brain and behavioral outcomes remain unclear. The glymphatic system (GS), a brain-wide clearance pathway, may provide a key mechanistic link. Methods:Leveraging baseline data from the Adolescent Brain Cognitive Development (ABCD) Study, we examined whether GS function mediates the effects of sleep on brain structure, cognition, and mental health. GS function was indexed by perivascular space (PVS) burden derived from structural MRI. Participants (n ≈ 6,800; age ≈ 11 years) were categorized into sleep-sufficient (≥9 h/night) and sleep-insufficient (<9 h/night) groups. Linear models tested associations among sleep, PVS burden, brain volumes, and behavioral outcomes. Mediation analyses evaluated whether PVS burden explained sleep-related effects. Results:Adolescents with insufficient sleep exhibited significantly greater PVS burden (Cohen's d ≈ 0.15), reduced cortical, subcortical, and white matter volumes, poorer cognitive performance across multiple domains (largest effect in crystallized intelligence, d ≈ 0.20), and elevated psychopathology (largest effect in general problems, d ≈ -0.34). Sleep duration and quality were strongly associated with PVS burden (p < 10-8). Mediation analyses revealed that PVS burden partially mediated sleep effects on cognition (e.g., crystallized intelligence, episodic memory) and mental health (e.g., psychosis severity), with indirect proportions up to 10.9%. Sequential models suggested a pathway from sleep → PVS → brain volume → behavior as the most plausible route. Conclusions:Insufficient sleep during adolescence is linked to glymphatic dysfunction, reflected by increased PVS burden, which partially accounts for adverse effects on brain structure, cognition, and mental health. These findings highlight the glymphatic system as a potential mechanistic pathway and imaging biomarker, underscoring the importance of promoting adequate sleep to support neurodevelopment and mental health.

Reports of sleep-specific brain activity patterns have been constrained by assessing brain function as it related to the conventional polysomnographic sleep stages. This limits the variety of sleep states and underlying activity patterns that one can discover. The current study used all-night functional MRI sleep data and defined sleep behaviorally with auditory arousal threshold (AAT) to characterize sleep depth better by searching for novel neural markers of sleep depth that are neuroanatomically localized and temporally unrelated to the conventional stages. Functional correlation values calculated in a four-min time window immediately before the determination of AAT were entered into a linear mixed effects model, allowing multiple arousals across the night per subject into the analysis, and compared to models with sleep stage to determine the unique relationships with AAT. These unique relationships were for thalamocerebellar correlations, the relationship between the right language network and the right "default-mode network dorsal medial prefrontal cortex subsystem," and the relationship between thalamus and ventral attention network. These novel neural markers of sleep depth would have remained undiscovered if the data were merely analyzed with the conventional sleep stages.

Understanding health differences among racial groups in child development is crucial for addressing inequalities that may affect various aspects of a child's life. However, factors such as household and neighborhood socioeconomic status (SES) often covary with health differences between races, making it challenging to accurately reveal these differences using conventional covariate-control methods such as multiple regression. Alternative methods, such as Propensity Score Matching (PSM), may provide better covariate control. Supporting this notion, we found that PSM is more sensitive than regression-based methods in detecting health differences between self-reported Black and White children across a wide range of behavioral and neural measurements in the ABCD (5636 White, 1350 Black). Puberty status, an index of physical maturation, emerged as the largest difference between races and mediated the health differences between races on the majority of behavioral and neural variables. These findings highlight the importance of controlling for pubertal status and using more effective covariate-control methods to accurately represent health differences between Black and White children.

Understanding the function of sleep requires studying the dynamics of brain activity across whole-night sleep and their transitions. However, current gold standard polysomnography (PSG) has limited spatial resolution to track brain activity. Additionally, previous fMRI studies were too short to capture full sleep stages and their cycling. To study whole-brain dynamics and transitions across whole-night sleep, we used an unsupervised learning approach, the Hidden Markov model (HMM), on two-night, 16 hr fMRI recordings of 12 non-sleep-deprived participants who reached all PSG-based sleep stages. This method identified 21 recurring brain states and their transition probabilities, beyond PSG-defined sleep stages. The HMM trained on one night accurately predicted the other, demonstrating unprecedented reproducibility. We also found functionally relevant subdivisions within rapid eye movement (REM) and within non-REM 2 stages. This study provides new insights into brain dynamics and transitions during sleep, aiding our understanding of sleep disorders that impact sleep transitions.

Approximately half of adolescents encounter a mismatch between their sleep patterns on school days and free days, also referred to as "social jetlag." This condition has been linked to various adverse outcomes, such as poor sleep, cognitive deficits, and mental disorders. However, prior research was unsuccessful in accounting for other variables that are correlated with social jetlag, including sleep duration and quality. To address this limitation, we applied a propensity score matching method on a sample of 6335 11-12-year-olds from the 2-year follow-up (FL2) data of the Adolescent Brain Cognitive Development study. We identified 2424 pairs of participants with high sleep-corrected social jetlag (SJLsc, over 1 hour) and low SJLsc (<= 1 hour) at FL2 (1728 pairs have neuroimaging data), as well as 1626 pairs at 3-year follow-up (FL3), after matching based on 11 covariates including socioeconomic status, demographics, and sleep duration and quality. Our results showed that high SJLsc, as measured by the Munich Chronotype Questionnaire, was linked to reduced crystallized intelligence (CI), lower school performance-grades, and decreased functional connectivity between cortical networks and subcortical regions, specifically between cingulo-opercular network and right hippocampus. Further mediation and longitudinal mediation analyses revealed that this connection mediated the associations between SJLsc and CI at FL2, and between SJLsc and grades at both FL2 and FL3. We validated these findings by replicating these results using objective SJLsc measurements obtained via Fitbit watches. Overall, our study highlights the negative association between social jetlag and CI during early adolescence.

Approximately half of adolescents encounter a mismatch between their sleep patterns on school days and free days, also referred to as "social jetlag". This condition has been linked to various adverse outcomes, such as poor sleep, cognitive deficits, and mental disorders. However, prior research was unsuccessful in accounting for other variables that are correlated with social jetlag, including sleep duration and quality. To address this limitation, we applied a propensity score matching method on a sample of 8853 11-12-year-olds from the two-year follow-up (FL2) data of the Adolescent Brain Cognitive Development (ABCD) study. We identified 3366 pairs of participants with high sleep-corrected social jetlag (SJLsc, over 1 hour) and low SJLsc (<= 1 hour) at FL2, as well as 1277 pairs at three-year follow-up (FL3), after matching based on 11 covariates including socioeconomic status, demographics, and sleep duration and quality. Our results showed that high SJLsc, as measured by the Munich Chronotype Questionnaire, was linked to reduced crystallized intelligence, lower school performance - grades, and decreased functional connectivity between cortical networks and subcortical regions, specifically between cingulo-opercular network and right hippocampus (cerc-hprh). Further mediation and longitudinal mediation analyses revealed that cerc-hprh connection mediated the associations between SJLsc and crystallized intelligence at FL2, and between SJLsc and grades at both FL2 and FL3. We validated these findings by replicating these results using objective SJLsc measurements obtained via Fitbit watches. Overall, our study highlights the negative association between social jetlag and crystallized intelligence during early adolescence.

Adolescence, a developmental period characterized by significant changes in sleep, is associated with normative increases in impulsivity. While short sleep duration has been linked to elevated impulsivity, the neural mechanism underlying the relationship between short sleep duration and elevated impulsivity remains poorly understood. We analyzed a dataset of 7,884 drug-naive 9–10 year-olds from the Adolescent Brain Cognitive Development (ABCD) study. Among them, 5,166 have two-year follow-up neuroimaging data. Linear mixed-effects models, mediation analyses, and longitudinal mediation analyses were used to investigate the relationship between parent-reported sleep duration, impulsivity, and functional and structural connectivity between the cortex and the striatum. We found that less sleep duration is significantly associated with higher positive and negative urgency, which are two affect-related components of impulsivity. In addition, we observed a link between short sleep duration and reduced corticostriatal connectivity. Neural pathways associated with short sleep duration—functional connectivity between the cingulo-opercular network and the left caudate, and between the cingulo-parietal network and the right pallidum—mediated the association between sleep duration and positive urgency both at baseline and two-year follow-up. Longitudinal mediation analyses further revealed that short sleep duration and elevated positive urgency exacerbated each other through these two corticostriatal connectivities. These findings highlight the key role of corticostriatal connectivities in the reciprocal relationship between short sleep duration and elevated impulsivity. Given the increasing prevalence of short sleep duration in adolescents, the link between sleep duration, impulsivity, and corticostriatal connectivities has important implications for timely interventions to address impulsive problems in early adolescents.

BACKGROUND:Adolescence, a developmental period characterized by significant changes in sleep, is associated with normative increases in impulsivity. While short sleep duration has been linked to elevated impulsivity, the neural mechanism underlying the relationship between short sleep duration and elevated impulsivity remains poorly understood.METHODS:We analyzed a dataset of 7,884 drug-naive 9-10 year-olds from the Adolescent Brain Cognitive Development (ABCD) study. Among them, 5,166 have two-year follow-up neuroimaging data. Linear mixed-effects models, mediation analyses, and longitudinal mediation analyses were used to investigate the relationship between parent-reported sleep duration, impulsivity, and functional and structural connectivity between the cortex and the striatum.RESULTS:We found that less sleep duration is significantly associated with higher positive and negative urgency, which are two affect-related components of impulsivity. In addition, we observed a link between short sleep duration and reduced corticostriatal connectivity. Neural pathways associated with short sleep duration-functional connectivity between the cingulo-opercular network and the left caudate, and between the cingulo-parietal network and the right pallidum-mediated the association between sleep duration and positive urgency both at baseline and two-year follow-up. Longitudinal mediation analyses further revealed that short sleep duration and elevated positive urgency exacerbated each other through these two corticostriatal connectivities.CONCLUSIONS:These findings highlight the key role of corticostriatal connectivities in the reciprocal relationship between short sleep duration and elevated impulsivity. Given the increasing prevalence of short sleep duration in adolescents, the link between sleep duration, impulsivity, and corticostriatal connectivities has important implications for timely interventions to address impulsive problems in early adolescents.

HIV-associated neurocognitive disorders (HAND) remain highly prevalent in people with HIV (PWH). Studies suggested that certain sociodemographic factors are associated with the risk of HAND in PWH. Here we investigated the impact of HIV infection and demographics on functional brain networks. One run of 8.5 min resting state functional MRI (fMRI) data was collected from 101 PWH (41–70 years old) and 40 demographically comparable controls. Functional connectivity (FC) was calculated using average wavelet coherence. The impact of demographic factors on FCs was investigated using canonical correlation analysis (CCA). Wavelet coherence analysis revealed a reduced within-network connectivity in the dorsal somatomotor network (dSMN), along with a reduced between-network connectivity between dSMN and medial temporal lobe (MTL) in PWH (compared to controls). Across all participants, CCA revealed that older age and HIV infection had negative impacts on network connectivity measures (mainly reduced within- and between-network FCs), whereas education had an opposite effect. In addition, being female at birth or a member of a minority ethnic/racial group was also associated with network disruptions. Our data suggested that advanced age and HIV infection are risk factors for functional brain network disruptions, whereas higher educational attainment was linked to better preserved functional network connectivity.

BACKGROUND:Although the American Academy of Sleep Medicine suggests at least 9 h of sleep per day for 6-12-year-olds, children in recent generations often report sleeping less than this amount. Because early adolescence is a crucial period for neurocognitive development, we aimed to investigate how insufficient sleep affects children's mental health, cognition, brain function, and brain structure over 2 years. METHODS:In this propensity score matched, longitudinal, observational cohort study, we obtained data from a population-based sample of 9-10-year-olds from 21 US study sites in the ongoing Adolescent Brain Cognitive Development (ABCD) study. Participants were categorised as having sufficient sleep or insufficient sleep on the basis of a cutoff of 9 h sleep per day. Using propensity score matching, we matched these two groups of participants on 11 key covariates, including sex, socioeconomic status, and puberty status. Participants were excluded from our analysis if they did not pass a baseline resting-state functional MRI quality check or had missing data for the covariates involved in propensity score matching. Outcome measures retrieved from the ABCD study were behavioural problems, mental health, cognition, and structural and resting-state functional brain measures, assessed at baseline and at 2-year follow-up. We examined group differences on these outcomes over those 2 years among all eligible participants. We then did mediation analyses of the neural correlates of behavioural changes induced by insufficient sleep. FINDINGS:Between Sept 1, 2016, and Oct 15, 2018, 11 878 individuals had baseline data collected for the ABCD study, of whom 8323 were eligible and included in this study (4142 participants in the sufficient sleep group and 4181 in the insufficient sleep group). Follow-up data were collected from July 30, 2018, to Jan 15, 2020. We identified 3021 matched sufficient sleep-insufficient sleep pairs at baseline and 749 matched pairs at 2-year follow-up, and observed similar differences between the groups in behaviour and neural measures at both timepoints; the effect sizes of between-group differences in behavioural measures at these two timepoints were significantly correlated with each other (r=0·85, 95% CI 0·73-0·92; p<0·0001). A similar pattern was observed in resting-state functional connectivity (r=0·54, 0·45-0·61; p<0·0001) and in structural measures (eg, in grey matter volume r=0·61, 0·51-0·69; p<0·0001). We found that cortico-basal ganglia functional connections mediate the effects of insufficient sleep on depression, thought problems, and crystallised intelligence, and that structural properties of the anterior temporal lobe mediate the effect of insufficient sleep on crystallised intelligence. INTERPRETATION:These results provide population-level evidence for the long-lasting effect of insufficient sleep on neurocognitive development in early adolescence. These findings highlight the value of early sleep intervention to improve early adolescents' long-term developmental outcomes. FUNDING:National Institutes of Health.

Background Neuronal dysfunction plays an important role in the high prevalence of HIV-associated neurocognitive disorders (HAND) in people with HIV (PWH). Transcranial direct current stimulation (tDCS)—with its capability to improve neuronal function—may have the potential to serve as an alternative therapeutic approach for HAND. Brain imaging and neurobehavioral studies provide converging evidence that injury to the anterior cingulate cortex (ACC) is highly prevalent and contributes to HAND in PWH, suggesting that ACC may serve as a potential neuromodulation target for HAND. Here we conducted a randomized, double-blind, placebo-controlled, partial crossover pilot study to test the safety, tolerability, and potential efficacy of anodal tDCS over cingulate cortex in adults with HIV, with a focus on the dorsal ACC (dACC). Methods Eleven PWH (47–69 years old, 2 females, 100% African Americans, disease duration 16–36 years) participated in the study, which had two phases, Phase 1 and Phase 2. During Phase 1, participants were randomized to receive ten sessions of sham (n = 4) or cingulate tDCS (n = 7) over the course of 2–3 weeks. Treatment assignments were unknown to the participants and the technicians. Neuropsychology and MRI data were collected from four additional study visits to assess treatment effects, including one baseline visit (BL, prior to treatment) and three follow-up visits (FU1, FU2, and FU3, approximately 1 week, 3 weeks, and 3 months after treatment, respectively). Treatment assignment was unblinded after FU3. Participants in the sham group repeated the study with open-label cingulate tDCS during Phase 2. Statistical analysis was limited to data from Phase 1. Results Compared to sham tDCS, cingulate tDCS led to a decrease in Perseverative Errors in Wisconsin Card Sorting Test (WCST), but not Non-Perseverative Errors, as well as a decrease in the ratio score of Trail Making Test—Part B (TMT-B) to TMT—Part A (TMT-A). Seed-to-voxel analysis with resting state functional MRI data revealed an increase in functional connectivity between the bilateral dACC and a cluster in the right dorsal striatum after cingulate tDCS. There were no differences in self-reported discomfort ratings between sham and cingulate tDCS. Conclusions Cingulate tDCS is safe and well-tolerated in PWH, and may have the potential to improve cognitive performance and brain function. A future study with a larger sample is warranted.

AbstractImportanceAdolescents nowadays often get insufficient sleep. Yet, the long-term adverse effects of sleep loss on developing brain and behavior remains unknown.ObjectiveTo determine whether insufficient sleep leads to long-lasting impacts on mental health, cognition, and brain development in adolescents across two years.DesignThis longitudinal study utilized a public dataset, the Adolescent Brain Cognitive Development (ABCD) study, which is an ongoing study starting from 2016.SettingData were collected from 21 research sites in the U.S.Participants11,875 9-10-year-olds were recruited using stratified sampling in order to reflect the diversity of the U.S. population.InterventionIndividuals with sufficient versus insufficient sleep (< 9 hours per day for adolescents) were compared after controlling for age (months), sex, race, puberty status, and other 7 covariates based on propensity score matching.Main Outcomes and MeasuresBehavior problems, cognition, mental health assessments, resting-state functional connectivity, gray matter volume, cortical area, cortical thickness, and structural connectivity (Fractional anisotropy) were collected and preprocessed by the ABCD study. Independent-sample t-tests and meditation analysis were performed to investigate the effects of insufficient sleep.Results3021 matched pairs (50.7% male) were identified based on baseline assessment, with mean (SD) age of 119.5 (7.5) months. In baseline, sufficient sleep is associated less behavioral problems on 18 of 20 assessments, e.g. depress (95% CI of mean difference: -0.28 to -0.47, false discovery rate (FDR)-corrected p□p□p□0.15), and large structure in ACC and temporal pole (all FDR-corrected p□0.09). Similar patterns of effect of sufficient sleep were found in FL2 (749 pairs remained) e.g. Cohen’s d of function connectivity at baseline was correlated with Cohen’s d of that at FL2 (r = 0.54, 95% CI: 0.45 to 0.61, p < 1e-10). Mediation and longitudinal mediation analysis revealed that identified brain measures (e.g. gray matter volume of left temporal pole) at baseline mediated the effect of sufficient sleep on behavioral assessments (e.g. crystal cognition) at baseline and at FL2 (95% CI did not encompass 0, p < 0.05 on 100,000 random-generated bootstrapped samples).Conclusions and RelevanceThese results provide strong population-level evidence for the long-lasting detrimental effects of insufficient sleep on mental health, cognition, and brain function and structure in adolescents. The current study identified potential neural mechanisms of adverse effect of insufficient sleep in adolescents, which might provide a theoretical grounding for sleep intervention programs to improve the long-term developmental outcomes in adolescents.Key pointsQuestionWhat are the long-lasting effects of insufficient sleep on neurocognitive development in early adolescents?FindingsIn this propensity score matching study that included 11,875 9-10-year-old participants, we identified long-lasting adverse effects of insufficient sleep on depression, thought problems, crystal cognition, neural network connectivity, cortical areas, and gray matter volume across 2 years.MeaningThis study elucidated the neural mechanisms underlying the long-term detriments of insufficient sleep on mental health and cognition, suggesting potential intervention targets to improve sleep-related outcomes.

Sleep disturbance is known to be associated with various mental disorders and often precedes the onset of mental disorders in youth. Given the increasingly acknowledged bidirectional influence between sleep disturbance and mental disorders, we aim to identify a shared neural mechanism that underlies sleep disturbance and mental disorders in preadolescents. We analyzed a dataset of 9,350 9-10 year-old children, among whom 8,845 had 1-year follow-up data, from the Adolescent Brain Cognitive Development (ABCD) study. Linear mixed-effects models, mediation analysis, and longitudinal mediation analysis were used to investigate the relationship between sleep disturbance, mental disorders, and resting-state network connectivity. Out of 186 unique connectivities, the effect of total sleep disturbance (TSP, from Sleep Disturbance Scale) and mental problems (MP, from Child Behavior Checklist) converged in the default mode network (DMN) and the dorsal attention network (DAN). Within- and between-network connectivities (DMN-DAN, DMN-DMN, DAN-DAN) mediated the relationship between baseline TSD and MP at 1-year follow-up and the relationship between baseline MP and TSD at 1-year follow-up. The pathway model in which sleep disturbance and mental problems affect each other through two anticorrelated brain networks (DMN and DAN) suggests a common neural mechanism between them. Longitudinally, a less segregated DMN and DAN is associated with negative outcomes on mental well-being and sleep disturbance a year later. These findings have important implications for the design of prevention and neurofeedback intervention for mental disorders and sleep problems.

IMPACT: If immune checkpoint blockade increases bacterial clearance with or without antibiotics in vitro, clinical appli-cation would be almost immediate and dramatic creating a seismic shift in the current therapeutic paradigm of periprosthetic joint infection. OBJECTIVES/GOALS: Periprosthetic joint infection (PJI) is a major cause of failure after joint replacement. Currently, the treatment of PJI relies on removing biofilm contaminated implants. Some of the bacteria within biofilm undergo a phenotypic shift becoming small colony variants (SCVs). SCVs induce local immunosuppression through PD-1/L1 signaling. METHODS/ ABSTRACT IMPACT: The knowledge acquired from my research can inform the development of early diagnostic methods for HIV-associated neurocognitive disorders. OBJECTIVES/GOALS: In the era of combina-tionantiretroviraltherapy(cART),theprevalenceofHIV-associatedneu-rocognitivedisorders(HAND)remainshighbuttheneuralmechanismsareunclear.WeexaminedwhetherolderpeoplewithHIV(PWH)withminimalcognitiveimpairmenthavereducedfunctionalconnectivityinfrontostriatalcircuitscomparedtocontrols.METHODS/STUDYPOPULATION:99PWH(meanage56.6years,75%male,62%Black,meandurationofHIV-infection26.2years ± 9.3, 90% viral load < 50 cop-ies, 98% on stable cART) and 38 demographically-comparable controls (mean age 54.5 years, 71% male, 58% Black) participated in a cross-sec-tional study. A 7-domain neuropsychological battery and an Activities of Daily Living index were used to determine HAND diagnoses: 32 PWH met criteria for asymptomatic to mild HAND. Motor skill was assessed using the Grooved Pegboard Test by measuring performance speed. Structural MRI and resting-state functional MRI were collected. Seed-to-voxelanalyseswereconductedusing4distinctregionsinthestria-tumasseedregions.Weusedavoxelthresholdofp < 0.001 and cluster threshold of p < 0.05 (FDR-corrected) after controlling for demographic variables. RESULTS/ANTICIPATED RESULTS: Compared to controls, PWH had lower resting state functional connectivity between the default mode region of the striatum (i.e., medial caudate) and bilateral superior frontal gyrus, supplementary motor cortex and paracingulate gyrus (p < 0.05; cluster size: 567 voxels). Also, compared to controls, PWH had reduced resting state functional connectivity between the motor divi-sionofthestriatum(i.e.,posteriorputamen)andanteriorcingulatecortexandleftsupplementarymotorcortex(p Our results support the hypothesis that frontostriatal abnor-malities are widely present in PWH and might play a key role in HAND development. Our data suggest that dysfunction within the frontostriatal circuits may be involved in motor impairment in PWH, and ongoing inflammation may contribute to motor impairment and frontostriatal injury. ABSTRACT IMPACT: Our data demonstrate that VC2 oncolytic virotherapy has significant clinical potential. OBJECTIVES/

ABSTRACT IMPACT: The knowledge acquired from my research can inform the development of early diagnostic methods for HIV-associated neurocognitive disorders. OBJECTIVES/GOALS: In the era of combination antiretroviral therapy (cART), the prevalence of HIV-associated neurocognitive disorders (HAND) remains high but the neural mechanisms are unclear. We examined whether older people with HIV (PWH) with minimal cognitive impairment have reduced functional connectivity in frontostriatal circuits compared to controls. METHODS/STUDY POPULATION: 99 PWH (mean age 56.6 years, 75% male, 62% Black, mean duration of HIV-infection 26.2 years ±9.3, 90% viral load <50 copies, 98% on stable cART) and 38 demographically-comparable controls (mean age 54.5 years, 71% male, 58% Black) participated in a cross-sectional study. A 7-domain neuropsychological battery and an Activities of Daily Living index were used to determine HAND diagnoses: 32 PWH met criteria for asymptomatic to mild HAND. Motor skill was assessed using the Grooved Pegboard Test by measuring performance speed. Structural MRI and resting-state functional MRI were collected. Seed-to-voxel analyses were conducted using 4 distinct regions in the striatum as seed regions. We used a voxel threshold of p<0.001 and cluster threshold of p<0.05 (FDR-corrected) after controlling for demographic variables. RESULTS/ANTICIPATED RESULTS: Compared to controls, PWH had lower resting state functional connectivity between the default mode region of the striatum (i.e., medial caudate) and bilateral superior frontal gyrus, supplementary motor cortex and paracingulate gyrus (p<0.05; cluster size: 567 voxels). Also, compared to controls, PWH had reduced resting state functional connectivity between the motor division of the striatum (i.e., posterior putamen) and anterior cingulate cortex and left supplementary motor cortex (p<0.05, cluster size: 405 voxels). Performance speed on the Grooved Pegboard motor test negatively correlated with functional connectivity between the motor region of the striatum and supplementary motor frontal regions in all participants (Spearman’s rho=-0.18, p=0.04). DISCUSSION/SIGNIFICANCE OF FINDINGS: Our results support the hypothesis that frontostriatal abnormalities are widely present in PWH and might play a key role in HAND development. Our data suggest that dysfunction within the frontostriatal circuits may be involved in motor impairment in PWH, and ongoing inflammation may contribute to motor impairment and frontostriatal injury.

IMPACT: If immune checkpoint blockade increases bacterial clearance with or without antibiotics in vitro, clinical application would be almost immediate and dramatic creating a seismic shift in the current therapeutic paradigm of periprosthetic joint infection. OBJECTIVES/GOALS: Periprosthetic joint infection (PJI) is a major cause of failure after joint replacement. Currently, the treatment of PJI relies on removing biofilm contaminated implants. Some of the bacteria within biofilm undergo a phenotypic shift becoming small colony variants (SCVs). SCVs induce local immunosuppression through PD-1/L1 signaling. METHODS/ STUDY POPULATION: We will infect cultured human macrophages and bone marrow aspirate with stable Staphylococcus aureus SVCs and treat with anti-PD-1 or anti-PD-L1monoclonal antibodies with and without antibiotics (e.g., gentamycin, cefazolin, vancomycin, rifampicin) and assess the residual bacterial viability.Wewill utilizemultiplexed ion beam imaging to quantify PD-1/L1 expression in human tissue from patients with a chronic PJI and compare those to patients undergoing an aseptic revision. Patients with a chronic PJI are likely to have increased expression of PD-1/L1 as their tissue samples are prospectively screened. RESULTS/ANTICIPATED RESULTS: SCVs reduce the phagocytic activity of macrophages and can survive intracellularly. SCVs also induce anti-inflammatory M2-macrophage polarization and recruit a heterogeneous group of immature monocytes and granulocytes called myeloid-derived suppressor cells (MDSC) to the periprosthetic microenvironment. M2macrophages and MDSCs then produce an immunosuppressive cytokine milieu characterized by increased IL-10 and decreased TNF-α. Clinically isolated SCVs up-regulate the expression of PDL1 and PD-L2 on the surface of macrophages, representing a mechanism by which SCVs induce host immunosuppression and survive immune clearance. Our preliminary data show PD-L1 expression during septic PJI, but not in aseptic revisions. DISCUSSION/ SIGNIFICANCE OF FINDINGS: If immune checkpoint blockade is shown to increase bacterial clearance with or without antibiotics, host immunomodulation would represent a novel class of therapeutic adjuvants to assist surgical debridement and antibiotic administration that could be superimposed on existing treatment algorithms to improve PJI related outcomes. 41224 REDUCED FRONTOSTRIATAL FUNCTIONAL CONNECTIVITY IN 41TO 70-YEAR-OLD ADULTS WITH HIV* Shiva Hassanzadeh-Behbahani1, Fan Nils Yang1, Margarita Bronshteyn1, Matthew Dawson2, Princy Kumar1, John VanMeter1, David J. Moore2, Ronald J. Ellis2 and Xiong Jiang1 1Georgetown University Medical Center and 2University of California San Diego ABSTRACT IMPACT: The knowledge acquired from my research can inform the development of early diagnostic methods for HIV-associated neurocognitive disorders. OBJECTIVES/GOALS: In the era of combination antiretroviral therapy (cART), the prevalence ofHIV-associatedneu-IMPACT: The knowledge acquired from my research can inform the development of early diagnostic methods for HIV-associated neurocognitive disorders. OBJECTIVES/GOALS: In the era of combination antiretroviral therapy (cART), the prevalence ofHIV-associatedneurocognitive disorders (HAND) remains high but the neural mechanisms are unclear. We examined whether older people with HIV (PWH) with minimal cognitive impairment have reduced functional connectivity in frontostriatal circuits compared to controls. METHODS/STUDY POPULATION: 99 PWH (mean age 56.6 years, 75% male, 62% Black, mean duration ofHIV-infection 26.2 years±9.3, 90% viral load<50 copies, 98% on stable cART) and 38 demographically-comparable controls (mean age 54.5 years, 71% male, 58% Black) participated in a cross-sectional study. A 7-domain neuropsychological battery and an Activities of Daily Living index were used to determine HAND diagnoses: 32 PWH met criteria for asymptomatic to mild HAND. Motor skill was assessed using the Grooved Pegboard Test by measuring performance speed. Structural MRI and resting-state functional MRI were collected. Seed-to-voxel analyseswereconductedusing4distinct regions in thestriatum as seed regions. We used a voxel threshold of p<0.001 and cluster threshold of p<0.05 (FDR-corrected) after controlling for demographic variables. RESULTS/ANTICIPATED RESULTS: Compared to controls, PWH had lower resting state functional connectivity between the default mode region of the striatum (i.e., medial caudate) and bilateral superior frontal gyrus, supplementary motor cortex and paracingulate gyrus (p<0.05; cluster size: 567 voxels). Also, compared to controls, PWH had reduced resting state functional connectivity between themotor division of the striatum (i.e., posterior putamen) and anterior cingulate cortex and left supplementary motor cortex (p<0.05, cluster size: 405 voxels). Performance speedon theGroovedPegboardmotor test negatively correlated with functional connectivity between the motor region of the striatum and supplementary motor frontal regions in all participants (Spearman’s rho=-0.18, p=0.04). DISCUSSION/SIGNIFICANCE OF FINDINGS: Our results support the hypothesis that frontostriatal abnormalities are widely present in PWH andmight play a key role in HAND development. Our data suggest that dysfunction within the frontostriatal circuits may be involved in motor impairment in PWH, and ongoing inflammation may contribute to motor impairment and frontostriatal injury.

Global cognitive performance plays an important role in the diagnosis of HIV-associated neurocognitive disorders (HAND), yet to date, there is no simple way to measure global cognitive performance in people with HIV (PWH). Here, we performed connectome-based predictive modeling (CPM) to pursue a neural biomarker of global cognitive performance in PWH based on whole-brain resting-state functional connectivity. We built a CPM model that successfully predicted individual differences in global cognitive performance in the training set of 67 PWH by using leave-one-out cross-validation. This model generalized to both 33 novel PWH in the testing set and a subset of 39 PWH who completed a follow-up visit two years later. Furthermore, network strengths identified by the CPM model were significantly different between PWH with HAND and without HAND. Together, these results demonstrate that whole-brain functional network strengths could serve as a potential neural biomarker of global cognitive performance in PWH.

IMPACT: This study has uncovered a novel surprising mechanism involving the epithelial adherens junctions and transposon regulation that can deepen our understanding of tumorigenesis. OBJECTIVES/GOALS: Recent studies show that genomic instability in 50% of tumors can be attributed to increased transposon activity, but the the reasons for this activity are unknown. We have evidence of a novelmechanism linking adherens junctionswith transposon regulation.Wehypothesize that adherens junctions suppress transposons to maintain genomic integrity.METHODS/STUDY POPULATION:We observed co-localization of PIWIL2 with adherens junction components of well differentiated epithelial breast, kidney and colon cell lines MCF10A, MDCK and CACO2, respectively, through immunofluorescence staining, confocal microscopy, and co-immunoprecipitation studies. Breast cancer cell linesMCF7andMDA-231were alsoobserved using immunofluorescence to determine the localization of PIWIL2 in cancer cell lines. shRNA knockdown of PIWIL2 in MCF10A cells, followed by western blot, immunofluorescence, and qRT-PCR was performed to confirm the knockdown, observe if transposons were upregulated, and determine the extent of DNA damage to the genome by themarker gamma-H2AX.RNA-seqwill be performed to determine piRNA sequences and possible targets of PIWIL2. RESULTS/ ANTICIPATED RESULTS: Our data have revealed an interaction of E-cadherin and p120 catenin, core components of adherens junctions, with PIWIL2, a member of the Argonaute family of proteins and a key component of the piRNA processing pathway that is responsible for transposon silencing. piRNAs (PIWI-interacting RNAs) are a distinct class of small RNAs that bind to PIWI proteins, and aid in transposon degradation.We found co-localization of PIWIL2 with E-cadherin and p120 catenin at adherens junctions ofwell-differentiated epithelial cells, whereas this association was lost in cancer cells. Furthermore, our data show that E-cadherin depletion results in mis-localization of PIWIL2 and TDRD1, another member of the PIWI complex. E-cadherin depletion also results in upregulation of transposons and ?-H2AX, an indicator of DNA damage. DISCUSSION/SIGNIFICANCE OF FINDINGS: Since both loss of junctional integrity and increased transposon activity are universal events in cancer, this study has the potential to further our understanding of the causes of tumorigenesis. Understanding themechanismsof transposonregulationhas thepotential to lead to a therapeutic target in the future.