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1.
Heliyon ; 10(5): e26788, 2024 Mar 15.
Article in English | MEDLINE | ID: mdl-38455583

ABSTRACT

To mitigate the effects of climate change, a significant percentage of future energy generation is set to come from renewable energy sources. This has led to a substantial increase of installed offshore wind in the North Sea in the last years (28 GW in 2021) and is projected to further accelerate to an installed capacity of 212 GW by 2050. Increasing the renewable energy grid penetration brings challenges, including 1) limitations in space availability and 2) the reliability of renewable energy systems in terms of grid balancing. In the North Sea, maritime space is getting scarce and the projected upscaling of offshore wind is putting pressure on the chemical-, biological, and physical balance of the marine ecosystem. Without economically viable large-scale storage systems, a renewable energy system focused on one intermittent source does not provide reliable baseload- and energy demand compliance. By integrating different supplementary offshore renewable energy sources into multi-source parks output becomes smoother, while the energy yield per area increases. Despite multiple studies stating the benefits of multi-source energy parks of either wind and wave energy or wind and PV energy, no study has been conducted on the co-location of all three offshore renewables. This study combines and analyzes the three offshore renewable energy sources: wave-, offshore PV- and wind energy in the example of Ten Noorden van de Waddeneilanden, a future wind farm north of the Dutch Wadden Islands. The additional renewables are allocated within the wind turbine spacing, taking into account safety zones and maintenance corridors. Co-location of these renewables increases the extracted energy density by 22%, making more efficient use of the limited available marine space. Moreover, the park output becomes smoother as the yearly-averaged coefficient of variation decreases by 13%, the capacity factor with respect to the export cable increases by 19%, and the hours where the output of the park is below 20% of the export cable capacity decreases by 86.5%.

2.
Nat Commun ; 14(1): 2311, 2023 04 21.
Article in English | MEDLINE | ID: mdl-37085475

ABSTRACT

As renewed interest in human space-exploration intensifies, a coherent and modernized strategy for mission design and planning has become increasingly crucial. Biotechnology has emerged as a promising approach to increase resilience, flexibility, and efficiency of missions, by virtue of its ability to effectively utilize in situ resources and reclaim resources from waste streams. Here we outline four primary mission-classes on Moon and Mars that drive a staged and accretive biomanufacturing strategy. Each class requires a unique approach to integrate biomanufacturing into the existing mission-architecture and so faces unique challenges in technology development. These challenges stem directly from the resources available in a given mission-class-the degree to which feedstocks are derived from cargo and in situ resources-and the degree to which loop-closure is necessary. As mission duration and distance from Earth increase, the benefits of specialized, sustainable biomanufacturing processes also increase. Consequentially, we define specific design-scenarios and quantify the usefulness of in-space biomanufacturing, to guide techno-economics of space-missions. Especially materials emerged as a potentially pivotal target for biomanufacturing with large impact on up-mass cost. Subsequently, we outline the processes needed for development, testing, and deployment of requisite technologies. As space-related technology development often does, these advancements are likely to have profound implications for the creation of a resilient circular bioeconomy on Earth.


Subject(s)
Mars , Space Flight , Humans , Moon , Biotechnology
3.
Front Neurosci ; 16: 829415, 2022.
Article in English | MEDLINE | ID: mdl-35516796

ABSTRACT

Background: Atypical processing of unfamiliar, but less so familiar, stimuli has been described in Autism Spectrum Disorder (ASD), in particular in relation to face processing. We examined the construct of familiarity in ASD using familiar and unfamiliar songs, to investigate the link between familiarity and autism symptoms, such as repetitive behavior. Methods: Forty-eight children, 24 with ASD (21 males, mean age = 9.96 years ± 1.54) and 24 typically developing (TD) controls (21 males, mean age = 10.17 ± 1.90) completed a music familiarity task using individually identified familiar compared to unfamiliar songs, while magnetoencephalography (MEG) was recorded. Each song was presented for 30 s. We used both amplitude envelope correlation (AEC) and the weighted phase lag index (wPLI) to assess functional connectivity between specific regions of interest (ROI) and non-ROI parcels, as well as at the whole brain level, to understand what is preserved and what is impaired in familiar music listening in this population. Results: Increased wPLI synchronization for familiar vs. unfamiliar music was found for typically developing children in the gamma frequency. There were no significant differences within the ASD group for this comparison. During the processing of unfamiliar music, we demonstrated left lateralized increased theta and beta band connectivity in children with ASD compared to controls. An interaction effect found greater alpha band connectivity in the TD group compared to ASD to unfamiliar music only, anchored in the left insula. Conclusion: Our results revealed atypical processing of unfamiliar songs in children with ASD, consistent with previous studies in other modalities reporting that processing novelty is a challenge for ASD. Relatively typical processing of familiar stimuli may represent a strength and may be of interest to strength-based intervention planning.

4.
Soc Cogn Affect Neurosci ; 17(4): 377-386, 2022 04 01.
Article in English | MEDLINE | ID: mdl-34654932

ABSTRACT

Very preterm (VPT: ≤32 weeks of gestational age) birth poses an increased risk for social and cognitive morbidities that persist throughout life. Resting-state functional network connectivity studies provide information about the intrinsic capacity for cognitive processing. We studied the following four social-cognitive resting-state networks: the default mode, salience, frontal-parietal and language networks. We examined functional connectivity using magnetoencephalography with individual head localization using each participant's MRI at 6 (n = 40) and 8 (n = 40) years of age compared to age- and sex-matched full-term (FT) born children (n = 38 at 6 years and n = 43 at 8 years). VPT children showed increased connectivity compared to FT children in the gamma band (30-80 Hz) at 6 years within the default mode network (DMN), and between the DMN and the salience, frontal-parietal and language networks, pointing to more diffuse, less segregated processing across networks at this age. At 8 years, VPT children had more social and academic difficulties. Increased DMN connectivity at 6 years was associated with social and working memory difficulties at 8 years. Therefore, we suggest that increased DMN connectivity contributes to the observed emerging social and cognitive morbidities in school age.


Subject(s)
Brain , Infant, Extremely Premature , Brain/diagnostic imaging , Brain Mapping , Child , Cognition , Humans , Infant, Newborn , Magnetic Resonance Imaging , Magnetoencephalography
5.
Hum Brain Mapp ; 42(17): 5747-5760, 2021 12 01.
Article in English | MEDLINE | ID: mdl-34582067

ABSTRACT

The ability to effectively and automatically regulate one's response to emotional information is a basic, fundamental skill for social functioning. The neural mechanisms underlying emotion regulation processing have been assessed, however few investigations have leveraged neurophysiological techniques, particularly magnetoencephalography (MEG) to determine the development of this critical ability. The current MEG study is the first to examine developmental changes in the neural mechanisms supporting automatic emotion regulation. We used an emotional go/no-go task with happy and angry faces in a single-site cohort of 97 healthy participants, 4-40 years of age. We found age-related changes as a function of emotion and condition in brain regions key to emotion regulation, including the right inferior frontal gyrus, orbitofrontal cortices and primarily right-lateralized temporal areas. Interaction effects, including an age by emotion and condition, were also found in the left angular gyrus, an area critical in emotion regulation and attention. Findings demonstrate protracted and nonlinear development, due to the adolescent group, of emotion regulation processing from child to adulthood, and highlight that age-related differences in emotion regulation are modulated by emotional face type.


Subject(s)
Cerebral Cortex/physiology , Emotional Regulation/physiology , Executive Function/physiology , Human Development/physiology , Inhibition, Psychological , Magnetoencephalography , Adolescent , Adult , Child , Child, Preschool , Facial Expression , Facial Recognition/physiology , Female , Humans , Male , Psychomotor Performance/physiology , Young Adult
6.
ACS Appl Nano Mater ; 4(8): 8334-8342, 2021 Aug 27.
Article in English | MEDLINE | ID: mdl-34485844

ABSTRACT

Graphene oxide (GO) has immense potential for widespread use in diverse in vitro and in vivo biomedical applications owing to its thermal and chemical resistance, excellent electrical properties and solubility, and high surface-to-volume ratio. However, development of GO-based biological nanocomposites and biosensors has been hampered by its poor intrinsic biocompatibility and difficult covalent biofunctionalization across its lattice. Many studies exploit the strategy of chemically modifying GO by noncovalent and reversible attachment of (bio)molecules or sole covalent biofunctionalization of residual moieties at the lattice edges, resulting in a low coating coverage and a largely bioincompatible composite. Here, we address these problems and present a facile yet powerful method for the covalent biofunctionalization of GO using colamine (CA) and the poly(ethylene glycol) cross-linker that results in a vast improvement in the biomolecular coating density and heterogeneity across the entire GO lattice. We further demonstrate that our biofunctionalized GO with CA as the cross-linker provides superior nonspecific biomolecule adhesion suppression with increased biomarker detection sensitivity in a DNA-biosensing assay compared to the (3-aminopropyl)triethoxysilane cross-linker. Our optimized biofunctionalization method will aid the development of GO-based in situ applications including biosensors, tissue nanocomposites, and drug carriers.

7.
Neuroimage ; 237: 118142, 2021 08 15.
Article in English | MEDLINE | ID: mdl-33951516

ABSTRACT

Recent work identified that patterns of distributed brain regions sharing similar myeloarchitecture are related to underlying functional connectivity, demonstrating cortical myelin's plasticity to changes in functional demand. However, the changing relations between functional and structural architecture throughout child and adulthood are poorly understood. We show that structural covariance connectivity (T1-weighted/T2-weighted ratio) and functional connectivity (magnetoencephalography) exhibit nonlinear developmental changes. We then show significant relations between structural and functional connectivity, which have shared and distinct characteristics dependent on the neural oscillatory frequency. Increases in structure-function coupling are visible during the protracted myelination observed throughout childhood and adolescence and are followed by decreases near the onset of adulthood. Our work lays the foundation for understanding the mechanisms by which myeloarchitecture supports brain function, enabling future investigations into how clinical populations may deviate from normative patterns.


Subject(s)
Brain Waves , Cerebral Cortex , Connectome , Magnetic Resonance Imaging , Magnetoencephalography , Myelin Sheath , Nerve Net , Adolescent , Adult , Brain Waves/physiology , Cerebral Cortex/anatomy & histology , Cerebral Cortex/diagnostic imaging , Cerebral Cortex/physiology , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Myelin Sheath/physiology , Nerve Net/anatomy & histology , Nerve Net/diagnostic imaging , Nerve Net/physiology , Young Adult
8.
PLoS One ; 16(4): e0249962, 2021.
Article in English | MEDLINE | ID: mdl-33909656

ABSTRACT

In-situ resource utilization (ISRU) is increasingly acknowledged as an essential requirement for the construction of sustainable extra-terrestrial colonies. Even with decreasing launch costs, the ultimate goal of establishing colonies must be the usage of resources found at the destination of interest. Typical approaches towards ISRU are often constrained by the mass and energy requirements of transporting processing machineries, such as rovers and massive reactors, and the vast amount of consumables needed. Application of self-reproducing bacteria for the extraction of resources is a promising approach to reduce these pitfalls. In this work, the bacterium Shewanella oneidensis was used to reduce three different types of Lunar and Martian regolith simulants, allowing for the magnetic extraction of iron-rich materials. The combination of bacterial treatment and magnetic extraction resulted in a 5.8-times higher quantity of iron and 43.6% higher iron concentration compared to solely magnetic extraction. The materials were 3D printed into cylinders and the mechanical properties were tested, resulting in a 400% improvement in compressive strength in the bacterially treated samples. This work demonstrates a proof of concept for the on-demand production of construction and replacement parts in space exploration.


Subject(s)
Iron/metabolism , Shewanella/metabolism , Compressive Strength , Iron/analysis , Iron/isolation & purification , Magnetics , Mars , Minerals/chemistry , Minerals/pharmacology , Moon , Printing, Three-Dimensional , Shewanella/chemistry , Shewanella/drug effects , Shewanella/growth & development , Silicon Dioxide/chemistry , Soil/chemistry
9.
Neurobiol Aging ; 96: 246-254, 2020 12.
Article in English | MEDLINE | ID: mdl-33049517

ABSTRACT

We have used the magnetisation transfer (MT) MRI measure as a primary measure of myelination in both the gray matter (GM) of the 78 cortical automated anatomical labeling (AAL) regions of the brain, and the underlying white matter in each region, in a cohort of healthy adults (aged 19-62 year old). The results revealed a significant quadratic trend in myelination with age, with average global myelination peaking at 42.9 year old in gray matter, and at 41.7 year old in white matter. We also explored the possibility of using the Nuclear Overhauser Enhancement (NOE) effect, which is acquired in a similar method to MT, as an additional measure of myelination. We found that the MT and NOE signals were strongly correlated in the brain and that the NOE effects displayed similar (albeit weaker) parabolic trends with age. We also investigated differences in cortical thickness with age, and confirmed a previous result of a linear decline of 4.5 ± 1.2 µm/y.


Subject(s)
Cerebral Cortex/diagnostic imaging , Cerebral Cortex/pathology , Gray Matter/diagnostic imaging , Gray Matter/pathology , Healthy Aging/pathology , Magnetic Resonance Imaging/methods , Myelin Sheath/pathology , White Matter/diagnostic imaging , White Matter/pathology , Adult , Female , Humans , Male , Middle Aged , Young Adult
10.
Neuroimage ; 219: 116995, 2020 10 01.
Article in English | MEDLINE | ID: mdl-32480036

ABSTRACT

Magnetoencephalography (MEG) is a powerful technique for functional neuroimaging, offering a non-invasive window on brain electrophysiology. MEG systems have traditionally been based on cryogenic sensors which detect the small extracranial magnetic fields generated by synchronised current in neuronal assemblies, however, such systems have fundamental limitations. In recent years, non-cryogenic quantum-enabled sensors, called optically-pumped magnetometers (OPMs), in combination with novel techniques for accurate background magnetic field control, have promised to lift those restrictions offering an adaptable, motion-robust MEG system, with improved data quality, at reduced cost. However, OPM-MEG remains a nascent technology, and whilst viable systems exist, most employ small numbers of sensors sited above targeted brain regions. Here, building on previous work, we construct a wearable OPM-MEG system with 'whole-head' coverage based upon commercially available OPMs, and test its capabilities to measure alpha, beta and gamma oscillations. We design two methods for OPM mounting; a flexible (EEG-like) cap and rigid (additively-manufactured) helmet. Whilst both designs allow for high quality data to be collected, we argue that the rigid helmet offers a more robust option with significant advantages for reconstruction of field data into 3D images of changes in neuronal current. Using repeat measurements in two participants, we show signal detection for our device to be highly robust. Moreover, via application of source-space modelling, we show that, despite having 5 times fewer sensors, our system exhibits comparable performance to an established cryogenic MEG device. While significant challenges still remain, these developments provide further evidence that OPM-MEG is likely to facilitate a step change for functional neuroimaging.


Subject(s)
Brain/diagnostic imaging , Equipment Design , Functional Neuroimaging/instrumentation , Head Protective Devices , Magnetoencephalography/instrumentation , Adult , Female , Humans , Male , Young Adult
11.
Neuroimage ; 209: 116537, 2020 04 01.
Article in English | MEDLINE | ID: mdl-31935517

ABSTRACT

Neural oscillations dominate electrophysiological measures of macroscopic brain activity and fluctuations in these rhythms offer an insightful window on cortical excitation, inhibition, and connectivity. However, in recent years the 'classical' picture of smoothly varying oscillations has been challenged by the idea that many 'oscillations' may actually be formed from the recurrence of punctate high-amplitude bursts in activity, whose spectral composition intersects the traditionally defined frequency ranges (e.g. alpha/beta band). This finding offers a new interpretation of measurable brain activity, however neither the methodological means to detect bursts, nor their link to other findings (e.g. connectivity) have been settled. Here, we use a new approach to detect bursts in magnetoencephalography (MEG) data. We show that a time-delay embedded Hidden Markov Model (HMM) can be used to delineate single-region bursts which are in agreement with existing techniques. However, unlike existing techniques, the HMM looks for specific spectral patterns in timecourse data. We characterise the distribution of burst duration, frequency of occurrence and amplitude across the cortex in resting state MEG data. During a motor task we show how the movement related beta decrease and post movement beta rebound are driven by changes in burst occurrence. Finally, we show that the beta band functional connectome can be derived using a simple measure of burst overlap, and that coincident bursts in separate regions correspond to a period of heightened coherence. In summary, this paper offers a new methodology for burst identification and connectivity analysis which will be important for future investigations of neural oscillations.


Subject(s)
Brain Waves/physiology , Cerebral Cortex/physiology , Connectome/methods , Magnetoencephalography/methods , Nerve Net/physiology , Pattern Recognition, Visual/physiology , Psychomotor Performance/physiology , Adult , Female , Humans , Male , Middle Aged , Young Adult
12.
J Immigr Minor Health ; 22(3): 494-502, 2020 Jun.
Article in English | MEDLINE | ID: mdl-31350680

ABSTRACT

To improve the coordination of long-term services and supports for dual-eligibles (those with both Medicare and Medicaid), California created Cal MediConnect (CMC), an Affordable Care Act-authorized managed care demonstration program. Beneficiaries were "passively enrolled" into CMC, meaning they were automatically enrolled unless they actively opted out. The aim of this study was to examine differences in factors influencing the enrollment decisions of U.S. born and immigrant dual-eligible beneficiaries. To explore differences in decision-making processes, we conducted in-depth interviews with dual-eligible consumers (39 native and 14 immigrant) in Los Angeles County. Interviews were analyzed using a constructivist grounded theory approach. Our findings illustrate a heightened sense of vulnerability and disempowerment experienced by immigrant participants. Immigrant participants also faced greater challenges in accessing healthcare and eliciting healthcare information compared to U.S.-born participants. Understanding the diverse perspectives of dual-eligible immigrant healthcare decision-making has implications for health care reform strategies aimed at ameliorating disparities for vulnerable immigrant populations.


Subject(s)
Eligibility Determination , Emigrants and Immigrants , Managed Care Programs , Medicaid , Medicare , Aged , California , Decision Making , Female , Humans , Interviews as Topic , Male , Middle Aged , Patient Protection and Affordable Care Act , Qualitative Research , United States
13.
Article in English | MEDLINE | ID: mdl-31706907

ABSTRACT

BACKGROUND: Visual regions develop rapidly in utero and throughout early childhood, but very preterm (VPT) birth can disrupt the typical maturation of primary cortices, with VPT children exhibiting mild visual impairments in early life and throughout development. This is thought to be due to dysfunctional maturation of occipital cortices. A way to readily index brain function is to examine neural oscillations; these mechanisms play a central role in the modeling and pruning of connections, providing an intrinsic temporal structure that refines the precise alignment of spiking, processing information in the brain, and coordinating networks. METHODS: Using magnetoencephalography, we examined regional oscillatory patterns and functional coupling in VPT and full-term children. Five minutes of eyes-open resting-state data were acquired from 27 VPT and 32 full-term children at 8 years of age. RESULTS: As hypothesized, the VPT group, when compared with control children, had elevated theta-band power, while alpha amplitude envelope coupling, a marker of connectivity, was found to be decreased. CONCLUSIONS: These results support the hypothesis of spectral slowing in VPT children and more broadly suggest that the developmental arc of visual neurophysiology is disrupted by VPT birth. We conclude that these deficits underlie difficulties in complex visual perceptual processing evident during childhood and beyond.


Subject(s)
Premature Birth , Visual Cortex , Brain , Female , Humans , Infant, Newborn , Magnetoencephalography , Neurophysiology , Pregnancy
14.
Sci Rep ; 9(1): 15757, 2019 10 31.
Article in English | MEDLINE | ID: mdl-31673006

ABSTRACT

Children born very preterm (VPT) often demonstrate selective difficulties in working memory (WM), which may underlie academic difficulties observed in this population. Despite this, few studies have investigated the functional networks underlying WM in young children born VPT, a period when cognitive deficits become apparent. Using magnetoencephalography, we examined the networks underlying the maintenance of visual information in 6-year-old VPT (n = 15) and full-term (FT; n = 20) children. Although task performance was similar, VPT children engaged different oscillatory mechanisms during WM maintenance. Within the FT group, we observed higher mean whole-brain connectivity in the alpha-band during the retention (i.e. maintenance) interval associated with correct compared to incorrect responses. VPT children showed reduced whole-brain alpha synchrony, and a different network organization with fewer connections. In the theta-band, VPT children demonstrated a slight increase in whole-brain connectivity during WM maintenance, and engaged similar network hubs as FT children in the alpha-band, including the left dorsolateral prefrontal cortex and superior temporal gyrus. These findings suggest that VPT children rely on the theta-band to support similar task performance. Altered oscillatory mechanisms may reflect a less mature pattern of functional recruitment underlying WM in VPT children, which may affect the processing in complex ecological situations.


Subject(s)
Brain/physiology , Cognition/physiology , Connectome , Infant, Extremely Premature/physiology , Magnetoencephalography , Memory, Short-Term/physiology , Child , Female , Humans , Infant, Newborn , Male
15.
ChemistryOpen ; 8(7): 888-895, 2019 Jul.
Article in English | MEDLINE | ID: mdl-31312588

ABSTRACT

Graphene's maximized surface-to-volume ratio, high conductance, mechanical strength, and flexibility make it a promising nanomaterial. However, large-scale graphene production is typically cost-intensive. This manuscript describes a microbial reduction approach for producing graphene that utilizes the bacterium Shewanella oneidensis in combination with modern nanotechnology to enable a low-cost, large-scale production method. The bacterial reduction approach presented in this paper increases the conductance of single graphene oxide flakes as well as bulk graphene oxide sheets by 2.1 to 2.7 orders of magnitude respectively while simultaneously retaining a high surface-area-to-thickness ratio. Shewanella-mediated reduction was employed in conjunction with electron-beam lithography to reduce one surface of individual graphene oxide flakes. This methodology yielded conducting flakes with differing functionalization on the top and bottom faces. Therefore, microbial reduction of graphene oxide enables the development and up-scaling of new types of graphene-based materials and devices with a variety of applications including nano-composites, conductive inks, and biosensors, while avoiding usage of hazardous, environmentally-unfriendly chemicals.

16.
J Vis Exp ; (147)2019 05 16.
Article in English | MEDLINE | ID: mdl-31157785

ABSTRACT

Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced antibiotic resistance, which poses potential health dangers, but can also be beneficial for environmental applications such as purification of drinking water. The further development of anti-bacterial therapeutics and biofilm-inspired applications will require the development of reproducible, engineerable methods for biofilm creation. Recently, a novel method of biofilm preparation using a modified three-dimensional (3D) printer with a bacterial ink has been developed. This article describes the steps necessary to build this efficient, low-cost 3D bioprinter that offers multiple applications in bacterially-induced materials processing. The protocol begins with an adapted commercial 3D printer in which the extruder has been replaced with a bio-ink dispenser connected to a syringe pump system enabling a controllable, continuous flow of bio-ink. To develop a bio-ink suitable for biofilm printing, engineered Escherichia coli bacteria were suspended in a solution of alginate, so that they solidify in contact with a surface containing calcium. The inclusion of an inducer chemical within the printing substrate drives expression of biofilm proteins within the printed bio-ink. This method enables 3D printing of various spatial patterns composed of discrete layers of printed biofilms. Such spatially-controlled biofilms can serve as model systems and can find applications in multiple fields that have a wide-ranging impact on society, including antibiotic resistance prevention or drinking water purification, among others.


Subject(s)
Biofilms , Bioprinting/instrumentation , Printing, Three-Dimensional , Biofilms/drug effects , Escherichia coli/drug effects , Escherichia coli/physiology , Hydrogels/pharmacology
17.
Netw Neurosci ; 3(2): 497-520, 2019.
Article in English | MEDLINE | ID: mdl-30984904

ABSTRACT

Detailed characterization of typical human neurodevelopment is key if we are to understand the nature of mental and neurological pathology. While research on the cellular processes of neurodevelopment has made great advances, in vivo human imaging is crucial to understand our uniquely human capabilities, as well as the pathologies that affect them. Using magnetoencephalography data in the largest normative sample currently available (324 participants aged 6-45 years), we assess the developmental trajectory of resting-state oscillatory power and functional connectivity from childhood to middle age. The maturational course of power, indicative of local processing, was found to both increase and decrease in a spectrally dependent fashion. Using the strength of phase-synchrony between parcellated regions, we found significant linear and nonlinear (quadratic and logarithmic) trajectories to be characterized in a spatially heterogeneous frequency-specific manner, such as a superior frontal region with linear and nonlinear trajectories in theta and gamma band respectively. Assessment of global efficiency revealed similar significant nonlinear trajectories across all frequency bands. Our results link with the development of human cognitive abilities; they also highlight the complexity of neurodevelopment and provide quantitative parameters for replication and a robust footing from which clinical research may map pathological deviations from these typical trajectories.

18.
Cereb Cortex ; 29(6): 2668-2681, 2019 06 01.
Article in English | MEDLINE | ID: mdl-29897408

ABSTRACT

Event-related fluctuations of neural oscillatory amplitude are reported widely in the context of cognitive processing and are typically interpreted as a marker of brain "activity". However, the precise nature of these effects remains unclear; in particular, whether such fluctuations reflect local dynamics, integration between regions, or both, is unknown. Here, using magnetoencephalography, we show that movement induced oscillatory modulation is associated with transient connectivity between sensorimotor regions. Further, in resting-state data, we demonstrate a significant association between oscillatory modulation and dynamic connectivity. A confound with such empirical measurements is that increased amplitude necessarily means increased signal-to-noise ratio (SNR): this means that the question of whether amplitude and connectivity are genuinely coupled, or whether increased connectivity is observed purely due to increased SNR is unanswered. Here, we counter this problem by analogy with computational models which show that, in the presence of global network coupling and local multistability, the link between oscillatory modulation and long-range connectivity is a natural consequence of neural networks. Our results provide evidence for the notion that connectivity is mediated by neural oscillations, and suggest that time-frequency spectrograms are not merely a description of local synchrony but also reflect fluctuations in long-range connectivity.


Subject(s)
Brain/physiology , Models, Neurological , Nerve Net/physiology , Neurons/physiology , Adult , Computer Simulation , Female , Humans , Magnetoencephalography , Male , Psychomotor Performance/physiology
19.
Schizophr Bull ; 45(4): 883-891, 2019 06 18.
Article in English | MEDLINE | ID: mdl-30239878

ABSTRACT

INTRODUCTION: Schizophrenia and schizotypal personality disorder (SPD) lie on a single spectrum of mental illness and converging evidence suggests similarities in the etiology of the 2 conditions. However, schizotypy is a heterogeneous facet of personality in the healthy population and so may be seen as a bridge between health and mental illness. Neural evidence for such a continuity would have implications for the characterization and treatment of schizophrenia. Based on our previous work identifying a relationship between symptomology in schizophrenia and abnormal movement-induced electrophysiological response (the post-movement beta rebound [PMBR]), we predicted that if subclinical schizotypy arises from similar neural mechanisms to schizophrenia, schizotypy in healthy individuals would be associated with reduced PMBR. METHODS: One-hundred sixteen participants completed a visuomotor task while their neural activity was recorded by magnetoencephalography. Partial correlations were computed between a measure of PMBR extracted from left primary motor cortex and scores on the Schizotypal Personality Questionnaire (SPQ), a self-report measure of schizotypal personality. Correlations between PMBR and SPQ factor scores measuring cognitive-perceptual, interpersonal and disorganization dimensions of schizotypy were also computed. Effects of site, age, and sex were controlled for. RESULTS: We found a significant negative correlation between total SPQ score and PMBR. This was most strongly mediated by variance shared between interpersonal and disorganization factor scores. CONCLUSION: These findings indicate a continuum of neural deficit between schizotypy and schizophrenia, with diminution of PMBR, previously reported in schizophrenia, also measurable in individuals with schizotypal features, particularly disorganization and impaired interpersonal relations.


Subject(s)
Beta Rhythm/physiology , Cerebral Cortex/physiopathology , Psychomotor Performance/physiology , Schizotypal Personality Disorder/physiopathology , Adult , Electromyography , Female , Humans , Individuality , Magnetic Resonance Imaging , Magnetoencephalography , Male , Middle Aged , Schizophrenia/physiopathology , Young Adult
20.
Dev Cogn Neurosci ; 34: 114-123, 2018 11.
Article in English | MEDLINE | ID: mdl-30336447

ABSTRACT

Working Memory (WM) supports a wide range of cognitive functions, and is positively associated with academic achievement. Although fMRI studies have revealed WM networks in adults, little is known about how these networks develop to support successful WM performance in children. Using magnetoencephalography, we examined the networks underlying the maintenance of visual information in 6-year-old children. We observed an increase in mean whole-brain connectivity that was specific to the alpha frequency band during the retention interval associated with correct compared to incorrect responses. Additionally, our network analysis revealed elevated alpha synchronization during WM maintenance in a distributed network of frontal, parietal and temporal regions. Central hubs in the network were lateralized to the left hemisphere with dominant fronto-temporal connections, including the dorsolateral prefrontal cortex, middle temporal and superior temporal gyri, as well as other canonical language areas. Local changes in power were also analysed for seeds of interest, including the left inferior parietal lobe, which revealed an increase in alpha power after stimulus onset that was sustained throughout the retention period of WM. Our results therefore implicate sustained fronto-temporal alpha synchrony during the retention interval with subsequent successful WM responses in children, which may be aided by subvocal rehearsal strategies.


Subject(s)
Alpha Rhythm/physiology , Magnetic Resonance Imaging/methods , Magnetoencephalography/methods , Memory, Short-Term/physiology , Child , Female , Humans , Male
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