Publications by authors named "Vinod Menon"

205 Publications

Latent brain state dynamics distinguish behavioral variability, impaired decision-making, and inattention.

Mol Psychiatry 2021 Feb 15. Epub 2021 Feb 15.

Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA.

Children with Attention Deficit Hyperactivity Disorder (ADHD) have prominent deficits in sustained attention that manifest as elevated intra-individual response variability and poor decision-making. Influential neurocognitive models have linked attentional fluctuations to aberrant brain dynamics, but these models have not been tested with computationally rigorous procedures. Here we use a Research Domain Criteria approach, drift-diffusion modeling of behavior, and a novel Bayesian Switching Dynamic System unsupervised learning algorithm, with ultrafast temporal resolution (490 ms) whole-brain task-fMRI data, to investigate latent brain state dynamics of salience, frontoparietal, and default mode networks and their relation to response variability, latent decision-making processes, and inattention. Our analyses revealed that occurrence of a task-optimal latent brain state predicted decreased intra-individual response variability and increased evidence accumulation related to decision-making. In contrast, occurrence and dwell time of a non-optimal latent brain state predicted inattention symptoms and furthermore, in a categorical analysis, distinguished children with ADHD from controls. Importantly, functional connectivity between salience and frontoparietal networks predicted rate of evidence accumulation to a decision threshold, whereas functional connectivity between salience and default mode networks predicted inattention. Taken together, our computational modeling reveals dissociable latent brain state features underlying response variability, impaired decision-making, and inattentional symptoms common to ADHD. Our findings provide novel insights into the neurobiology of attention deficits in children.
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http://dx.doi.org/10.1038/s41380-021-01022-3DOI Listing
February 2021

Dissociation by Network Integration.

Authors:
Vinod Menon

Am J Psychiatry 2021 02;178(2):110-112

Department of Psychiatry and Behavioral Sciences and Department of Neurology and Neurological Sciences, Stanford Neurosciences Institute, Stanford University School of Medicine, Stanford, Calif.

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http://dx.doi.org/10.1176/appi.ajp.2020.20121728DOI Listing
February 2021

Long-term effects of intermittent early life stress on primate prefrontal-subcortical functional connectivity.

Neuropsychopharmacology 2021 Jan 25. Epub 2021 Jan 25.

Department of Psychiatry and Behavioral Sciences, Stanford, USA.

Correlational studies of humans suggest that exposure to early life stress has long-term effects on neural circuits involved in vulnerability and resilience to mental health disorders. Stress-related mental health disorders are more prevalent in women than in men. Here, female squirrel monkeys are randomized to intermittently stressful (IS) social separations or a non-separated (NS) control condition conducted from 17 to 27 weeks of age. Nine years later in mid-life adulthood, resting-state functional magnetic resonance imaging was employed to parcellate prefrontal cortex (PFC). Resulting subdivisions were then used to characterize functional connectivity within PFC, and between PFC subdivisions and subcortical regions that are known to be altered by stress. Extensive hyper-connectivity of medial and orbitofrontal PFC with amygdala, hippocampus, and striatum was observed in IS compared to NS monkeys. Functional hyper-connectivity in IS monkeys was associated with previously reported indications of diminished anxiety-like behavior induced by prepubertal stress. Hyper-connectivity of PFC with amygdala and with hippocampus was also associated with increased ventral striatal dopamine D2 and/or D3 receptor (DRD2/3) availability assessed with positron emission tomography (PET) of [C]raclopride binding in adulthood. Ventral striatal DRD2/3 availability has been linked to cognitive control, which plays a key role in stress coping as an aspect of emotion regulation. These findings provide causal support for enduring neurobiological effects of early life stress and suggest novel targets for new treatments of stress-related mental health disorders.
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http://dx.doi.org/10.1038/s41386-021-00956-0DOI Listing
January 2021

Time-Varying Functional Connectivity Decreases as a Function of Acute Nicotine Abstinence.

Biol Psychiatry Cogn Neurosci Neuroimaging 2020 Oct 19. Epub 2020 Oct 19.

Neuroimaging Research Branch, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, Baltimore, Maryland. Electronic address:

Background: The nicotine withdrawal syndrome (NWS) includes affective and cognitive disruptions whose incidence and severity vary across time during acute abstinence. However, most network-level neuroimaging uses static measures of resting-state functional connectivity and assumes time-invariance and is thus unable to capture dynamic brain-behavior relationships. Recent advances in resting-state functional connectivity signal processing allow characterization of time-varying functional connectivity (TVFC), which characterizes network communication between networks that reconfigure over the course of data collection. Therefore, TVFC may more fully describe network dysfunction related to the NWS.

Methods: To isolate alterations in the frequency and diversity of communication across network boundaries during acute nicotine abstinence, we scanned 25 cigarette smokers in the nicotine-sated and abstinent states and applied a previously validated method to characterize TVFC at a network and a nodal level within the brain.

Results: During abstinence, we found brain-wide decreases in the frequency of interactions between network nodes in different modular communities (i.e., temporal flexibility). In addition, within a subset of the networks examined, the variability of these interactions across community boundaries (i.e., spatiotemporal diversity) also decreased. Finally, within 2 of these networks, the decrease in spatiotemporal diversity was significantly related to NWS clinical symptoms.

Conclusions: Using multiple measures of TVFC in a within-subjects design, we characterized a novel set of changes in network communication and linked these changes to specific behavioral symptoms of the NWS. These reductions in TVFC provide a meso-scale network description of the relative inflexibility of specific large-scale brain networks during acute abstinence.
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http://dx.doi.org/10.1016/j.bpsc.2020.10.004DOI Listing
October 2020

The first modified Delphi consensus statement on sleeve gastrectomy.

Surg Endosc 2021 Jan 12. Epub 2021 Jan 12.

Cleveland Clinic, Cleveland, USA.

Introduction: Sleeve gastrectomy (SG) is the commonest bariatric procedure worldwide. Yet there is significant variation in practice concerning its various aspects. This paper report results from the first modified Delphi consensus-building exercise on SG.

Methods: We established a committee of 54 globally recognized opinion makers in this field. The committee agreed to vote on several statements concerning SG. An agreement or disagreement amongst ≥ 70.0% experts was construed as a consensus.

Results: The committee achieved a consensus of agreement (n = 71) or disagreement (n = 7) for 78 out of 97 proposed statements after two rounds of voting. The committee agreed with 96.3% consensus that the characterization of SG as a purely restrictive procedure was inaccurate and there was 88.7% consensus that SG was not a suitable standalone, primary, surgical weight loss option for patients with Barrett's esophagus (BE) without dysplasia. There was an overwhelming consensus of 92.5% that the sleeve should be fashioned over an orogastric tube of 36-40 Fr and a 90.7% consensus that surgeons should stay at least 1 cm away from the angle of His. Remarkably, the committee agreed with 81.1% consensus that SG patients should undergo a screening endoscopy every 5 years after surgery to screen for BE.

Conclusion: A multinational team of experts achieved consensus on several aspects of SG. The findings of this exercise should help improve the outcomes of SG, the commonest bariatric procedure worldwide, and guide future research on this topic.
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http://dx.doi.org/10.1007/s00464-020-08216-wDOI Listing
January 2021

Damage-Free Atomic Layer Etch of WSe: A Platform for Fabricating Clean Two-Dimensional Devices.

ACS Appl Mater Interfaces 2021 Jan 22;13(1):1930-1942. Epub 2020 Dec 22.

Department of Electrical Engineering, Columbia University, New York, New York 10027-6902, United States.

The development of a controllable, selective, and repeatable etch process is crucial for controlling the layer thickness and patterning of two-dimensional (2D) materials. However, the atomically thin dimensions and high structural similarity of different 2D materials make it difficult to adapt conventional thin-film etch processes. In this work, we propose a selective, damage-free atomic layer etch (ALE) that enables layer-by-layer removal of monolayer WSe without altering the physical, optical, and electronic properties of the underlying layers. The etch uses a top-down approach where the topmost layer is oxidized in a self-limited manner and then removed using a selective etch. Using a comprehensive set of material, optical, and electrical characterization, we show that the quality of our ALE processed layers is comparable to that of pristine layers of similar thickness. The ALE processed WSe layers preserve their bright photoluminescence characteristics and possess high room-temperature hole mobilities of 515 cm/V·s, essential for fabricating high-performance 2D devices. Further, using graphene as a testbed, we demonstrate the fabrication of ultra-clean 2D devices using a sacrificial monolayer WSe layer to protect the channel during processing, which is etched in the final process step in a technique we call sacrificial WSe with ALE processing (SWAP). The graphene transistors made using the SWAP technique demonstrate high room-temperature field-effect mobilities, up to 200,000 cm/V·s, better than previously reported unencapsulated graphene devices.
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http://dx.doi.org/10.1021/acsami.0c18390DOI Listing
January 2021

Bariatric surgery for patients with type 2 diabetes mellitus requiring insulin: Clinical outcome and cost-effectiveness analyses.

PLoS Med 2020 12 7;17(12):e1003228. Epub 2020 Dec 7.

National Bariatric Surgical Registry (NBSR)/British Obesity and Metabolic Surgical Society (BOMSS), Royal College of Surgeons of England, London, United Kingdom.

Background: Although bariatric surgery is well established as an effective treatment for patients with obesity and type 2 diabetes mellitus (T2DM), there exists reluctance to increase its availability for patients with severe T2DM. The aims of this study were to examine the impact of bariatric surgery on T2DM resolution in patients with obesity and T2DM requiring insulin (T2DM-Ins) using data from a national database and to develop a health economic model to evaluate the cost-effectiveness of surgery in this cohort when compared to best medical treatment (BMT).

Methods And Findings: Clinical data from the National Bariatric Surgical Registry (NBSR), a comprehensive database of bariatric surgery in the United Kingdom, were extracted to analyse outcomes of patients with obesity and T2DM-Ins who underwent primary bariatric surgery between 2009 and 2017. Outcomes for this group were combined with data sourced from a comprehensive literature review in order to develop a state-transition microsimulation model to evaluate cost-effectiveness of bariatric surgery versus BMT for patients over a 5-year time horizon. The main outcome measure for the clinical study was insulin cessation at 1-year post-surgery: relative risks (RR) summarising predictive factors were determined, unadjusted, and after adjusting for variables including age, initial body mass index (BMI), duration of T2DM, and weight loss. Main outcome measures for the economic evaluation were total costs, total quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER) at willingness-to-pay threshold of GBP£20,000. A total of 2,484 patients were eligible for inclusion, of which 1,847 had 1-year follow-up data (mean age of 51 years, mean initial BMI 47.2 kg/m2, and 64% female). 67% of patients no longer required insulin at 1-year postoperatively: these rates persisted for 4 years. Roux-en-Y gastric bypass (RYGB) was associated with a higher rate of insulin cessation (71.7%) than sleeve gastrectomy (SG; 64.5%; RR 0.92, confidence interval (CI) 0.86-0.99) and adjustable gastric band (AGB; 33.6%; RR 0.45, CI 0.34-0.60; p < 0.001). When adjusted for percentage total weight loss and demographic variables, insulin cessation following surgery was comparable for RYGB and SG (RR 0.97, CI 0.90-1.04), with AGB having the lowest cessation rates (RR 0.55, CI 0.40-0.74; p < 0.001). Over 5 years, bariatric surgery was cost saving compared to BMT (total cost GBP£22,057 versus GBP£26,286 respectively, incremental difference GBP£4,229). This was due to lower treatment costs as well as reduced diabetes-related complications costs and increased health benefits. Limitations of this study include loss to follow-up of patients within the NBSR dataset and that the time horizon for the economic analysis is limited to 5 years. In addition, the study reflects current medical and surgical treatment regimens for this cohort of patients, which may change.

Conclusions: In this study, we observed that in patients with obesity and T2DM-Ins, bariatric surgery was associated with high rates of postoperative cessation of insulin therapy, which is, in turn, a major driver of overall reductions in direct healthcare cost. Our findings suggest that a strategy utilising bariatric surgery for patients with obesity and T2DM-Ins is cost saving to the national healthcare provider (National Health Service (NHS)) over a 5-year time horizon.
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http://dx.doi.org/10.1371/journal.pmed.1003228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7721482PMC
December 2020

Older age does not influence the success of weight loss through the implementation of lifestyle modification.

Clin Endocrinol (Oxf) 2021 Feb 6;94(2):204-209. Epub 2020 Nov 6.

Division of Biomedical Sciences, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospitals Coventry and Warwickshire, Coventry, UK.

Objective: Age is sometimes a barrier for acceptance of patients into a hospital-based obesity service. Our aim was to explore the effect of age on the ability to lose weight through lifestyle interventions, implemented within a hospital-based obesity service.

Design: Retrospective study.

Patients: We included a cohort of randomly selected patients with morbid obesity (n = 242), who attended our hospital-based obesity service during 2005-2016 and received only lifestyle weight loss interventions.

Measurements: Primary outcome measures were percentage weight loss (%WL) and percentage reduction in body mass index (%rBMI) following implemented lifestyle interventions. Data were stratified according to patient age at referral: group 1 (age < 60 years, n = 167) and group 2 (age ≥ 60 years, n = 75). Weight loss was compared between groups, and correlations with age at referral were explored.

Results: The duration of hospital-based weight loss interventions ranged between 1 and 143 months (mean: 38.9 months; SD: 32.3). Baseline BMI at referral differed significantly between groups 1 and 2 (49.7 kgm [SD: 8.7] vs 46.9 kgm [SD: 6.1], respectively; P < .05). Following implemented lifestyle interventions, between groups 1 and 2 there were no differences in %WL (6.9% [SD: 16.7] vs 7.3% [SD: 11.60], respectively; P = NS) or %rBMI (8.1% [SD: 14.9] vs 7.8% [SD: 11.7], respectively; p = NS). Overall, there was no significant correlation between patient age at referral and %WL (r = -.13, p = NS).

Conclusions: Older age does not influence the success of weight loss through the implementation of lifestyle modification within a hospital-based obesity service. Therefore, age per se should not influence clinical decisions regarding acceptance of patients to hospital-based obesity services.
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http://dx.doi.org/10.1111/cen.14354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7821294PMC
February 2021

Impact of COVID-19 on Obesity Management Services in the United Kingdom (The COMS-UK study).

Obes Surg 2021 02 13;31(2):904-908. Epub 2020 Oct 13.

Division of Surgery and Cancer, Imperial College London, London, W2 1NY, UK.

Coronavirus Disease-2019 (COVID-19) has had a severe impact on all aspects of global healthcare delivery. This study aimed to investigate the nationwide impact of the pandemic on obesity management services in the UK in a questionnaire-based survey conducted of professionals involved in the delivery. A total of 168 clinicians took the survey; the majority of which maintained their usual clinical roles and were not redeployed except physicians and nurse specialists. Nearly all (97.8%) elective bariatric surgery was cancelled, 67.3% of units cancelled all multidisciplinary meeting activity, and the majority reduced clinics (69.6%). Most respondents anticipated that the services would recommence within 1-3 months. This study found that the COVID-19 pandemic has had a severe impact on the services involved in the management of patients suffering from severe, complex obesity in the UK.
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http://dx.doi.org/10.1007/s11695-020-05005-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7552587PMC
February 2021

Plasmonic enhancement of stability and brightness in organic light-emitting devices.

Nature 2020 09 16;585(7825):379-382. Epub 2020 Sep 16.

Universal Display Corporation, Ewing, NJ, USA.

The field of plasmonics, which studies the resonant interactions of electromagnetic waves and free electrons in solid-state materials, has yet to be put to large-scale commercial application owing to the large amount of loss that usually occurs in plasmonic materials. Organic light-emitting devices (OLEDs) have been incorporated into billions of commercial products because of their good colour saturation, versatile form factor and low power consumption, but could still be improved in terms of efficiency and stability. Although OLEDs incorporating organic phosphors achieve an internal charge-to-light conversion of unity, their refractive index contrast reduces the observable fraction of photons outside the device to around 25 per cent. Further, during OLED operation, a localized buildup of slow-decaying triplet excitons and charges gradually reduces the brightness of the device in a process called ageing, which can result in 'burn-in' effects on the display. Simultaneously improving device efficiency and stability is of paramount importance for OLED technology. Here we demonstrate an OLED that uses the decay rate enhancement of a plasmonic system to increase device stability, while maintaining efficiency by incorporating a nanoparticle-based out-coupling scheme to extract energy from the plasmon mode. Using an archetypal phosphorescent emitter, we achieve a two-fold increase in operational stability at the same brightness as a reference conventional device while simultaneously extracting 16 per cent of the energy from the plasmon mode as light. Our approach to increasing OLED stability avoids material-specific designs and is applicable to all commercial OLEDs that are currently used for lighting panels, televisions and mobile displays.
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http://dx.doi.org/10.1038/s41586-020-2684-zDOI Listing
September 2020

Brain networks and cognitive impairment in psychiatric disorders.

Authors:
Vinod Menon

World Psychiatry 2020 Oct;19(3):309-310

Departments of Psychiatry and Behavioral Sciences, and of Neurology and Neurological Sciences, Stanford Neurosciences Institute, Stanford University School of Medicine, Stanford, CA, USA.

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http://dx.doi.org/10.1002/wps.20799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7491636PMC
October 2020

Modification of fecal microbiota as a mediator of effective weight loss and metabolic benefits following bariatric surgery.

Expert Rev Endocrinol Metab 2020 09 25;15(5):363-373. Epub 2020 Aug 25.

Division of Biomedical Sciences, Warwick Medical School, University of Warwick , Coventry, UK.

Introduction: Bariatric surgery (primarily Laparoscopic Sleeve Gastrectomy [LSG] and Roux-en-Y Gastric Bypass [RYGB]) is an efficacious and durable therapeutic option for weight loss in obesity. The mechanisms that mediate weight loss following bariatric surgery remain incompletely understood.

Areas Covered: Pubmed search of published data on fecal microbiota, metabolic health, LSG, and RYGB. The fecal microbiome plays a key role in the establishment and maintenance of metabolic wellbeing, and may also contribute (through fecal dysbiosis) to metabolic dysfunction. LSG and RYGB both result in characteristic, procedure-specific changes to the fecal microbiota that may mediate at least some of the resultant weight-loss and metabolically beneficial effects, when applied to the management of obesity.

Expert Opinion: The human fecal microbiome, containing around 100 trillion microbes, evolved over millions of years and interacts symbiotically with its human host. Rodent-based studies have provided insights into the complexities of the gut-microbiome-brain axis. This includes the important role of the gut microbiome in the mediation of normal immunological development, inflammatory pathways, metabolic functioning, hypothalamic appetite regulation, and the absorption of essential nutrients as by-products of bacterial metabolism. Fecal transformation is likely to provide an important therapeutic target for future prevention and management of obesity and metabolic dysfunction.
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http://dx.doi.org/10.1080/17446651.2020.1801412DOI Listing
September 2020

Microstructural organization of human insula is linked to its macrofunctional circuitry and predicts cognitive control.

Elife 2020 06 4;9. Epub 2020 Jun 4.

Parietal, Inria Saclay Île-de-France, CEA Université Paris Sud, Palaiseau, France.

The human insular cortex is a heterogeneous brain structure which plays an integrative role in guiding behavior. The cytoarchitectonic organization of the human insula has been investigated over the last century using postmortem brains but there has been little progress in noninvasive in vivo mapping of its microstructure and large-scale functional circuitry. Quantitative modeling of multi-shell diffusion MRI data from 413 participants revealed that human insula microstructure differs significantly across subdivisions that serve distinct cognitive and affective functions. Insular microstructural organization was mirrored in its functionally interconnected circuits with the anterior cingulate cortex that anchors the salience network, a system important for adaptive switching of cognitive control systems. Furthermore, insular microstructural features, confirmed in Macaca mulatta, were linked to behavior and predicted individual differences in cognitive control ability. Our findings open new possibilities for probing psychiatric and neurological disorders impacted by insular cortex dysfunction, including autism, schizophrenia, and fronto-temporal dementia.
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http://dx.doi.org/10.7554/eLife.53470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7308087PMC
June 2020

Ultralong-Range Energy Transport in a Disordered Organic Semiconductor at Room Temperature Via Coherent Exciton-Polariton Propagation.

Adv Mater 2020 Jul 2;32(28):e2002127. Epub 2020 Jun 2.

Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, 48109, USA.

Amorphous molecular solids are inherently disordered, exhibiting strong exciton localization. Optical microcavities containing such disordered excitonic materials have been theoretically shown to support both propagating and localized exciton-polariton modes. Here, the ultrastrong coupling of a Bloch surface wave photon and molecular excitons in a disordered organic thin film at room temperature is demonstrated, where the major fraction of the polaritons are propagating states. The delocalized exciton-polariton has a group velocity as high as 3 × 10 m s and a lifetime of 500 fs, leading to propagation distances of over 100 µm from the excitation source. The polariton intensity shows a halo-like pattern that is due to self-interference of the polariton mode, from which a coherence length of 20 µm is derived and is correlated with phase breaking by polariton scattering. The demonstration of ultralong-range exciton-polariton transport at room temperature promises new photonic and optoelectronic applications such as efficient energy transfer in disordered condensed matter systems.
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http://dx.doi.org/10.1002/adma.202002127DOI Listing
July 2020

Intrinsic functional architecture of the human speech processing network.

Cortex 2020 Aug 21;129:41-56. Epub 2020 Apr 21.

Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA; Program in Neuroscience, Stanford University School of Medicine, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA. Electronic address:

Speech engages distributed temporo-fronto-parietal brain regions, however a comprehensive understanding of its intrinsic functional network architecture is lacking. Here we investigate the human speech processing network using the largest sample to date, high temporal resolution resting-state fMRI data, network stability analysis, and theoretically informed models. Network consensus analysis revealed three stable functional modules encompassing: (1) superior temporal plane (STP) and Area Spt, (2) superior temporal sulcus (STS) + ventral frontoparietal cortex, and (3) dorsal frontoparietal cortex. The STS + ventral frontoparietal cortex module showed the highest participation coefficient, and a hub-like organization linking STP with frontoparietal cortical nodes. Node-wise analysis revealed key connectivity features underlying this modular architecture, including a leftward asymmetric connectivity profile, and differential connectivity of STS and STP, with frontoparietal cortex. Our findings, replicated across cohorts, reveal a tripartite functional network architecture supporting speech processing and provide a novel template for future studies.
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http://dx.doi.org/10.1016/j.cortex.2020.03.013DOI Listing
August 2020

Spatiotemporal Integrity and Spontaneous Nonlinear Dynamic Properties of the Salience Network Revealed by Human Intracranial Electrophysiology: A Multicohort Replication.

Cereb Cortex 2020 Sep;30(10):5309-5321

Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.

The salience network (SN) plays a critical role in cognitive control and adaptive human behaviors, but its electrophysiological foundations and millisecond timescale dynamic temporal properties are poorly understood. Here, we use invasive intracranial EEG (iEEG) from multiple cohorts to investigate the neurophysiological underpinnings of the SN and identify dynamic temporal properties that distinguish it from the default mode network (DMN) and dorsolateral frontal-parietal network (FPN), two other large-scale brain networks that play important roles in human cognition. iEEG analysis of network interactions revealed that the anterior insula and anterior cingulate cortex, which together anchor the SN, had stronger intranetwork interactions with each other than cross-network interactions with the DMN and FPN. Analysis of directionality of information flow between the SN, DMN, and FPN revealed causal outflow hubs in the SN consistent with its role in fast temporal switching of network interactions. Analysis of regional iEEG temporal fluctuations revealed faster temporal dynamics and higher entropy of neural activity within the SN, compared to the DMN and FPN. Critically, these results were replicated across multiple cohorts. Our findings provide new insights into the neurophysiological basis of the SN, and more broadly, foundational mechanisms underlying the large-scale functional organization of the human brain.
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http://dx.doi.org/10.1093/cercor/bhaa111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566690PMC
September 2020

Anxiety and Stress Alter Decision-Making Dynamics and Causal Amygdala-Dorsolateral Prefrontal Cortex Circuits During Emotion Regulation in Children.

Biol Psychiatry 2020 Oct 21;88(7):576-586. Epub 2020 Feb 21.

Department of Psychiatry and Behavioral Sciences, Stanford School of Medicine, Stanford, California. Electronic address:

Background: Anxiety and stress reactivity are risk factors for the development of affective disorders. However, the behavioral and neurocircuit mechanisms that potentiate maladaptive emotion regulation are poorly understood. Neuroimaging studies have implicated the amygdala and dorsolateral prefrontal cortex (DLPFC) in emotion regulation, but how anxiety and stress alter their context-specific causal circuit interactions is not known. Here, we use computational modeling to inform affective pathophysiology, etiology, and neurocircuit targets for early intervention.

Methods: Forty-five children (10-11 years of age; 25 boys) reappraised aversive stimuli during functional magnetic resonance imaging scanning. Clinical measures of anxiety and stress were acquired for each child. Drift-diffusion modeling of behavioral data and causal circuit analysis of functional magnetic resonance imaging data, with a National Institute of Mental Health Research Domain Criteria approach, were used to characterize latent behavioral and neurocircuit decision-making dynamics driving emotion regulation.

Results: Children successfully reappraised negative responses to aversive stimuli. Drift-diffusion modeling revealed that emotion regulation was characterized by increased initial bias toward positive reactivity during viewing of aversive stimuli and increased drift rate, which captured evidence accumulation during emotion evaluation. Crucially, anxiety and stress reactivity impaired latent behavioral dynamics associated with reappraisal and decision making. Anxiety and stress increased dynamic casual influences from the right amygdala to DLPFC. In contrast, DLPFC, but not amygdala, reactivity was correlated with evidence accumulation and decision making during emotion reappraisal.

Conclusions: Our findings provide new insights into how anxiety and stress in children impact decision making and amygdala-DLPFC signaling during emotion regulation, and uncover latent behavioral and neurocircuit mechanisms of early risk for psychopathology.
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http://dx.doi.org/10.1016/j.biopsych.2020.02.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442664PMC
October 2020

Laparoscopic Adjustable Gastric Banding-Should a Second Chance Be Given?

Obes Surg 2020 Aug;30(8):2913-2919

Department of Endocrinology and Metabolic Medicine, King's College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS, UK.

Background: Obesity is a chronic relapsing-remitting disease and a global pandemic, being associated with multiple comorbidities. Laparoscopic adjustable gastric banding (LAGB) is one of the safest surgical procedures used for the treatment of obesity, and even though its popularity has been decreasing over time, it still remains an option for a certain group of patients, producing considerable weight loss and improvement in obesity-associated comorbidities.

Methods: The aim of this study was to evaluate the impact of weight loss following LAGB on obesity-associated comorbidities, and to identify factors that could predict better response to surgery, and patient sub-groups exhibiting greatest benefit. A total of 99 severely obese patients (81.2% women, mean age 44.19 ± 10.94 years, mean body mass index (BMI) 51.84 ± 8.77 kg/m) underwent LAGB in a single institution. Results obtained 1, 2, and 5 years postoperatively were compared with the pre-operative values using SPPS software version 20.

Results: A significant drop in BMI was recorded throughout the follow-up period, as well as in A1c and triglycerides, with greatest improvement seen 2 years after surgery (51.8 ± 8.7 kg/m vs 42.3 ± 9.2 kg/m, p < 0.05, 55.5 ± 19.1 mmol/mol vs 45.8 ± 13.7 mmol/mol, p < 0.05, and 2.2 ± 1.7 mmol/l vs 1.5 ± 0.6 mmol/l). Better outcomes were seen in younger patients, with lower duration of diabetes before surgery, and lower pre-operative systolic blood pressure.

Conclusions: Younger age, lower degree of obesity, and lower severity of comorbidities at the time of surgery can be important predictors of successful weight loss, making this group of patients the ideal candidates for LAGB.
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http://dx.doi.org/10.1007/s11695-020-04613-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7305253PMC
August 2020

The visual word form area (VWFA) is part of both language and attention circuitry.

Nat Commun 2019 12 6;10(1):5601. Epub 2019 Dec 6.

Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, 94394, USA.

While predominant models of visual word form area (VWFA) function argue for its specific role in decoding written language, other accounts propose a more general role of VWFA in complex visual processing. However, a comprehensive examination of structural and functional VWFA circuits and their relationship to behavior has been missing. Here, using high-resolution multimodal imaging data from a large Human Connectome Project cohort (N = 313), we demonstrate robust patterns of VWFA connectivity with both canonical language and attentional networks. Brain-behavior relationships revealed a striking pattern of double dissociation: structural connectivity of VWFA with lateral temporal language network predicted language, but not visuo-spatial attention abilities, while VWFA connectivity with dorsal fronto-parietal attention network predicted visuo-spatial attention, but not language abilities. Our findings support a multiplex model of VWFA function characterized by distinct circuits for integrating language and attention, and point to connectivity-constrained cognition as a key principle of human brain organization.
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http://dx.doi.org/10.1038/s41467-019-13634-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6898452PMC
December 2019

Faster learners transfer their knowledge better: Behavioral, mnemonic, and neural mechanisms of individual differences in children's learning.

Dev Cogn Neurosci 2019 12 15;40:100719. Epub 2019 Oct 15.

Department of Psychiatry & Behavioral Sciences, Stanford, CA 94305, United States; Department of Neurology & Neurological Sciences, Stanford, CA 94305, United States; Stanford Neurosciences Institute, Stanford University School of Medicine, Stanford, CA 94305, United States. Electronic address:

Why some children learn, and transfer their knowledge to novel problems, better than others remains an important unresolved question in the science of learning. Here we developed an innovative tutoring program and data analysis approach to investigate individual differences in neurocognitive mechanisms that support math learning and "near" transfer to novel, but structurally related, problems in elementary school children. Following just five days of training, children performed recently trained math problems more efficiently, with greater use of memory-retrieval-based strategies. Crucially, children who learned faster during training performed better not only on trained problems but also on novel problems, and better discriminated trained and novel problems in a subsequent recognition memory task. Faster learners exhibited increased similarity of neural representations between trained and novel problems, and greater differentiation of functional brain circuits engaged by trained and novel problems. These results suggest that learning and near transfer are characterized by parallel learning-rate dependent local integration and large-scale segregation of functional brain circuits. Our findings demonstrate that speed of learning and near transfer are interrelated and identify the neural mechanisms by which faster learners transfer their knowledge better. Our study provides new insights into the behavioral, mnemonic, and neural mechanisms underlying children's learning.
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http://dx.doi.org/10.1016/j.dcn.2019.100719DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974913PMC
December 2019

Inhibition-related modulation of salience and frontoparietal networks predicts cognitive control ability and inattention symptoms in children with ADHD.

Mol Psychiatry 2019 Oct 29. Epub 2019 Oct 29.

Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, 94305, USA.

Attention-deficit hyperactivity disorder (ADHD) is associated with pervasive impairments in attention and cognitive control. Although brain circuits underlying these impairments have been extensively investigated with resting-state fMRI, little is known about task-evoked functional brain circuits and their relation to cognitive control deficits and inattention symptoms in children with ADHD. Children with ADHD and age, gender and head motion matched typically developing (TD) children completed a Go/NoGo fMRI task. We used multivariate and dimensional analyses to investigate impairments in two core cognitive control systems: (i) cingulo-opercular "salience" network (SN) anchored in the right anterior insula, dorsal anterior cingulate cortex (rdACC), and ventrolateral prefrontal cortex (rVLPFC) and (ii) dorsal frontoparietal "central executive" (FPN) network anchored in right dorsolateral prefrontal cortex (rDLPFC) and posterior parietal cortex (rPPC). We found that multivariate patterns of task-evoked effective connectivity between brain regions in SN and FPN distinguished the ADHD and TD groups, with rDLPFC-rPPC connectivity emerging as the most distinguishing link. Task-evoked rdACC-rVLPFC connectivity was positively correlated with NoGo accuracy, and negatively correlated with severity of inattention symptoms. Brain-behavior relationships were robust against potential age, gender, and head motion confounds. Our findings highlight aberrancies in task-evoked modulation of SN and FPN connectivity in children with ADHD. Crucially, cingulo-frontal connectivity was a common locus of deficits in cognitive control and clinical measures of inattention symptoms. Our study provides insights into a parsimonious systems neuroscience model of cognitive control deficits in ADHD, and suggests specific circuit biomarkers for predicting treatment outcomes in childhood ADHD.
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http://dx.doi.org/10.1038/s41380-019-0564-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188596PMC
October 2019

Hyperdirect insula-basal-ganglia pathway and adult-like maturity of global brain responses predict inhibitory control in children.

Nat Commun 2019 10 22;10(1):4798. Epub 2019 Oct 22.

Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, 94305, USA.

Inhibitory control is fundamental to children's self-regulation and cognitive development. Here we investigate cortical-basal ganglia pathways underlying inhibitory control in children and their adult-like maturity. We first conduct a comprehensive meta-analysis of extant neurodevelopmental studies of inhibitory control and highlight important gaps in the literature. Second, we examine cortical-basal ganglia activation during inhibitory control in children ages 9-12 and demonstrate the formation of an adult-like inhibitory control network by late childhood. Third, we develop a neural maturation index (NMI), which assesses the similarity of brain activation patterns between children and adults, and demonstrate that higher NMI in children predicts better inhibitory control. Fourth, we show that activity in the subthalamic nucleus and its effective connectivity with the right anterior insula predicts children's inhibitory control. Fifth, we replicate our findings across multiple cohorts. Our findings provide insights into cortical-basal ganglia circuits and global brain organization underlying the development of inhibitory control.
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http://dx.doi.org/10.1038/s41467-019-12756-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6805945PMC
October 2019

A room-temperature polariton light-emitting diode based on monolayer WS.

Nat Nanotechnol 2019 11 23;14(11):1024-1028. Epub 2019 Sep 23.

Department of Physics, City College of New York, City University of New York, New York, USA.

Exciton polaritons that arise through the strong coupling of excitons and cavity photons are used to demonstrate a wide array of fundamental phenomena and potential applications that range from Bose-Einstein-like condensation to analogue Hamiltonian simulators and chip-scale interferometers. Recently, the two-dimensional (2D) transition metal dichalcogenides (TMDs), because of their large exciton binding energies, oscillator strength and valley degree of freedom, have emerged as a very attractive platform to realize exciton polaritons at elevated temperatures. Achieving the electrical injection of polaritons is attractive both as a precursor to realizing electrically driven polariton lasers as well as for high speed light-emitting diodes (LEDs) for communication systems. Here, we demonstrate an electrically driven polariton LED that operates at room temperature using monolayer tungsten disulfide (WS) as the emissive material. The extracted external quantum efficiency is ~0.1% and is comparable to recent demonstrations of bulk organic and carbon nanotube-based polariton electroluminescence (EL) devices. The possibility to realize electrically driven polariton LEDs in atomically thin semiconductors at room temperature presents a promising step towards achieving an inversionless electrically driven laser in these systems as well as for ultrafast microcavity LEDs using van der Waals (vdW) materials.
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http://dx.doi.org/10.1038/s41565-019-0543-6DOI Listing
November 2019

Direct Observation of Gate-Tunable Dark Trions in Monolayer WSe.

Nano Lett 2019 10 9;19(10):6886-6893. Epub 2019 Sep 9.

Department of Chemical and Biological Engineering , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States.

Spin-forbidden intravalley dark excitons in tungsten-based transition-metal dichalcogenides (TMDCs), because of their unique spin texture and long lifetime, have attracted intense research interest. Here, we show that we can control the dark exciton electrostatically by dressing it with one free electron or free hole, forming the dark trions. The existence of the dark trions is suggested by the unique magneto-photoluminescence spectroscopy pattern of the boron nitride (BN)-encapsulated monolayer WSe device at low temperature. The unambiguous evidence of the dark trions is further obtained by directly resolving the radiation pattern of the dark trions through back focal plane imaging. The dark trions possess a binding energy of ∼15 meV, and they inherit the long lifetime and large -factor from the dark exciton. Interestingly, under the out-of-plane magnetic field, dressing the dark exciton with one free electron or hole results in distinctively different valley polarization of the emitted photon, as a result of the different intervalley scattering mechanism for the electron and hole. Finally, the lifetime of the positive dark trion can be further tuned from ∼50 ps to ∼215 ps by controlling the gate voltage. The gate-tunable dark trions usher in new opportunities for excitonic optoelectronics and valleytronics.
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http://dx.doi.org/10.1021/acs.nanolett.9b02132DOI Listing
October 2019

Guiding of visible photons at the ångström thickness limit.

Nat Nanotechnol 2019 09 12;14(9):844-850. Epub 2019 Aug 12.

Department of Nanoengineering, University of California, San Diego, La Jolla, CA, USA.

Optical waveguides are vital components of data communication system technologies, but their scaling down to the nanoscale has remained challenging despite advances in nano-optics and nanomaterials. Recently, we theoretically predicted that the ultimate limit of visible photon guiding can be achieved in monolayer-thick transition metal dichalcogenides. Here, we present an experimental demonstration of light guiding in an atomically thick tungsten disulfide membrane patterned as a photonic crystal structure. In this scheme, two-dimensional tungsten disulfide excitonic photoluminescence couples into quasi-guided photonic crystal modes known as resonant-type Wood's anomalies. These modes propagate via total internal reflection with only a small portion of the light diffracted to the far field. Such light guiding at the ultimate limit provides more possibilities to miniaturize optoelectronic devices and to test fundamental physical concepts.
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http://dx.doi.org/10.1038/s41565-019-0519-6DOI Listing
September 2019

Development of Human Emotion Circuits Investigated Using a Big-Data Analytic Approach: Stability, Reliability, and Robustness.

J Neurosci 2019 09 22;39(36):7155-7172. Epub 2019 Jul 22.

Department of Psychiatry and Behavioral Sciences,

Emotion perception is fundamental to affective and cognitive development and is thought to involve distributed brain circuits. Efforts to chart neurodevelopmental changes in emotion have been severely hampered by narrowly focused approaches centered on activation of individual brain regions and small sample sizes. Here we investigate the maturation of human functional brain circuits associated with identification of fearful, angry, sad, happy, and neutral faces using a large sample of 759 children, adolescents, and adults (ages 8-23; female/male = 419/340). Network analysis of emotion-related brain circuits revealed three functional modules, encompassing lateral frontoparietal, medial prefrontal-posterior cingulate, and subcortical-posterior insular cortices, with hubs in medial prefrontal, but not posterior cingulate, cortex. This overall network architecture was stable by age 8, and it anchored maturation of circuits important for salience detection and cognitive control, as well as dissociable circuit patterns across distinct emotion categories. Our findings point to similarities and differences in functional circuits associated with identification of fearful, angry, sad, happy, and neutral faces, and reveal aspects of brain circuit organization underlying emotion perception that are stable over development as well as features that change with age. Reliability analyses demonstrated the robustness of our findings and highlighted the importance of large samples for probing functional brain circuit development. Our study emphasizes a need to focus beyond amygdala circuits and provides a robust neurodevelopmental template for investigating emotion perception and identification in psychopathology. Emotion perception is fundamental to cognitive and affective development. However, efforts to chart neurodevelopmental changes in emotion perception have been hampered by narrowly focused approaches centered on the amygdala and prefrontal cortex and small sample sizes. Using a large sample of 759 children, adolescents, and adults and a multipronged analytical strategy, we investigated the development of brain network organization underlying identification and categorization of fearful, happy, angry, sad, and neutral facial expressions. Results revealed a developmentally stable modular architecture that anchored robust age-related and emotion category-related changes in brain connectivity across multiple brain systems that extend far beyond amygdala circuits and provide a new template for investigation of emotion processing in the developing brain.
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http://dx.doi.org/10.1523/JNEUROSCI.0220-19.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6733549PMC
September 2019

An Examination of Who Is Eligible and Who Is Receiving Bariatric Surgery in England: Secondary Analysis of the Health Survey for England Dataset.

Obes Surg 2019 10;29(10):3246-3251

Warwick Medical School, Coventry, UK.

Background: Over 2 million people in England were estimated to be eligible for bariatric surgery in 2006. In 2014, clinical guidelines were updated, widening potential eligibility, meanwhile, obesity prevalence rose. However, numbers receiving surgery decreased, and concerns exist of inequalities in access between population groups. This study is aimed at estimating the number of adults eligible for surgery in England and to compare demographics with those that receive surgery.

Methods: BMI and comorbidity status were used to determine eligibility for bariatric surgery within participants of the 2014 Health Survey for England dataset (6938 adults), based on the National Institute of Health and Care Excellence guidelines. Results were scaled up using national population estimates. The demographics of eligible participants were compared against 2014/2015 hospital episode statistics for sex and age group using a chi-squared analysis.

Results: Of the total population of England, 7.78% (95% CI 7.1-8.6%), or 3,623,505 people, could have been eligible for bariatric surgery in 2014; nearly a million more than if previous guidelines applied. Eligibility peaked at ages 45-54, with most in the 35-64 age group (58.9%). 58.4% of those eligible were women. Patients receiving surgery were far more likely to be female than male (76.1%) and the distribution skewed towards younger ages when compared with those eligible.

Conclusion: Bariatric surgery may benefit many people in England; significant investment is required so that service provision is adequate for demand. Differences between demographics of those eligible and receiving surgery may be explainable; however, the potential health inequality should be investigated.
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http://dx.doi.org/10.1007/s11695-019-03977-3DOI Listing
October 2019

Quantitative analysis of heterogeneity in academic achievement of children with autism.

Clin Psychol Sci 2019 Mar 14;7(2):362-380. Epub 2018 Nov 14.

Department of Psychiatry and Behavioral Sciences, Stanford University.

Autism spectrum disorders (ASD) represent a quintessential example of a clinical population with diverse symptom presentations and marked variation in cognitive abilities. However, the extent literature lacks rigorous quantitative procedures for characterizing heterogeneity of cognitive abilities in these individuals. Here we employ novel clustering and cross-validation procedures to investigate the stability of heterogeneous patterns of cognitive abilities in reading and math in a relatively large sample (N=114) of children with ASD and matched controls (N=96). Our analysis revealed a unique profile of heterogeneity in ASD, consisting of a low-achieving subgroup with poor math skills compared to reading, and a high-achieving subgroup who showed superior math skills compared to reading. Verbal and central executive working memory skills further differentiated these subgroups. Findings provide insights into distinct profiles of academic achievement in children with ASD, with implications for educational practice and intervention, and provide a novel framework for quantifying heterogeneity in the disorder.
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http://dx.doi.org/10.1177/2167702618809353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483392PMC
March 2019

Polariton chemistry: Thinking inside the (photon) box.

Proc Natl Acad Sci U S A 2019 03 11;116(12):5214-5216. Epub 2019 Mar 11.

Department of Physics, City College and Graduate Center, City University of New York, New York, NY 10031

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http://dx.doi.org/10.1073/pnas.1900795116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6431159PMC
March 2019

Impaired voice processing in reward and salience circuits predicts social communication in children with autism.

Elife 2019 02 26;8. Epub 2019 Feb 26.

Program in Neuroscience, Stanford University School of Medicine, Stanford, United States.

Engaging with vocal sounds is critical for children's social-emotional learning, and children with autism spectrum disorder (ASD) often 'tune out' voices in their environment. Little is known regarding the neurobiological basis of voice processing and its link to social impairments in ASD. Here, we perform the first comprehensive brain network analysis of voice processing in children with ASD. We examined neural responses elicited by unfamiliar voices and mother's voice, a biologically salient voice for social learning, and identified a striking relationship between social communication abilities in children with ASD and activation in key structures of reward and salience processing regions. Functional connectivity between voice-selective and reward regions during voice processing predicted social communication in children with ASD and distinguished them from typically developing children. Results support the Social Motivation Theory of ASD by showing reward system deficits associated with the processing of a critical social stimulus, mother's voice, in children with ASD.

Editorial Note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that minor issues remain unresolved (see decision letter).
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http://dx.doi.org/10.7554/eLife.39906DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391069PMC
February 2019