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1.
Small ; : e2308072, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38698574

RESUMO

Tunnel junctions comprising self-assembled monolayers (SAMs) from liquid crystal-inspired molecules show a pronounced hysteretic current-voltage response, due to electric field-driven dipole reorientation in the SAM. This renders these junctions attractive device candidates for emerging technologies such as in-memory and neuromorphic computing. Here, the novel molecular design, device fabrication, and characterization of such resistive switching devices with a largely improved performance, compared to the previously published work are reported. Those former devices suffer from a stochastic switching behavior limiting reliability, as well as from critically small read-out currents. The present progress is based on replacing Al/AlOx with TiN as a new electrode material and as a key point, on redesigning the active molecular material making up the SAM: a previously present, flexible aliphatic moiety has been replaced by a rigid aromatic linker, thereby introducing a molecular "ratchet". This restricts the possible molecular conformations to only two major states of opposite polarity. The above measures have resulted in an increase of the current density by five orders of magnitude as well as in an ON/OFF conductance ratio which is more than ten times higher than the individual scattering ranges of the high and low resistance states.

2.
Neuroimage ; 218: 116934, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32416227

RESUMO

When we read, our eyes move through the text in a series of fixations and high-velocity saccades to extract visual information. This process allows the brain to obtain meaning, e.g., about sentiment, or the emotional valence, expressed in the written text. How exactly the brain extracts the sentiment of single words during naturalistic reading is largely unknown. This is due to the challenges of naturalistic imaging, which has previously led researchers to employ highly controlled, timed word-by-word presentations of custom reading materials that lack ecological validity. Here, we aimed to assess the electrical neural correlates of word sentiment processing during naturalistic reading of English sentences. We used a publicly available dataset of simultaneous electroencephalography (EEG), eye-tracking recordings, and word-level semantic annotations from 7129 words in 400 sentences (Zurich Cognitive Language Processing Corpus; Hollenstein et al., 2018). We computed fixation-related potentials (FRPs), which are evoked electrical responses time-locked to the onset of fixations. A general linear mixed model analysis of FRPs cleaned from visual- and motor-evoked activity showed a topographical difference between the positive and negative sentiment condition in the 224-304 â€‹ms interval after fixation onset in left-central and right-posterior electrode clusters. An additional analysis that included word-, phrase-, and sentence-level sentiment predictors showed the same FRP differences for the word-level sentiment, but no additional FRP differences for phrase- and sentence-level sentiment. Furthermore, decoding analysis that classified word sentiment (positive or negative) from sentiment-matched 40-trial average FRPs showed a 0.60 average accuracy (95% confidence interval: [0.58, 0.61]). Control analyses ruled out that these results were based on differences in eye movements or linguistic features other than word sentiment. Our results extend previous research by showing that the emotional valence of lexico-semantic stimuli evoke a fast electrical neural response upon word fixation during naturalistic reading. These results provide an important step to identify the neural processes of lexico-semantic processing in ecologically valid conditions and can serve to improve computer algorithms for natural language processing.


Assuntos
Emoções/fisiologia , Leitura , Adulto , Encéfalo/fisiologia , Mapeamento Encefálico , Eletroencefalografia , Potencial Evocado Motor/fisiologia , Potenciais Evocados Visuais/fisiologia , Medições dos Movimentos Oculares , Movimentos Oculares , Feminino , Fixação Ocular/fisiologia , Humanos , Idioma , Masculino , Pessoa de Meia-Idade , Psicolinguística , Desempenho Psicomotor/fisiologia , Reprodutibilidade dos Testes , Adulto Jovem
3.
Eur J Neurosci ; 47(7): 800-811, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29461657

RESUMO

Human-environment interactions are mediated through the body and occur within the peripersonal space (PPS), the space immediately adjacent to and surrounding the body. The PPS is taken to be a critical interface between the body and the environment, and indeed, body-part specific PPS remapping has been shown to depend on body-part utilization, such as upper limb movements in otherwise static observers. How vestibular signals induced by whole-body movement contribute to PPS representation is less well understood. In a series of experiments, we mapped the spatial extension of the PPS around the head while participants were submitted to passive whole-body rotations inducing vestibular stimulation. Forty-six participants, in three experiments, executed a tactile detection reaction time task while task-irrelevant auditory stimuli approached them. The maximal distance at which the auditory stimulus facilitated tactile reaction time was taken as a proxy for the boundary of peri-head space. The present results indicate two distinct vestibular effects. First, vestibular stimulation speeded tactile detection indicating a vestibular facilitation of somatosensory processing. Second, vestibular stimulation modulated audio-tactile interaction of peri-head space in a rotation direction-specific manner. Congruent but not incongruent audio-vestibular motion stimuli expanded the PPS boundary further away from the body as compared to no rotation. These results show that vestibular inputs dynamically update the multisensory delineation of PPS and far space, which may serve to maintain accurate tracking of objects close to the body and to update spatial self-representations.


Assuntos
Espaço Pessoal , Vestíbulo do Labirinto/fisiologia , Estimulação Acústica , Adolescente , Adulto , Feminino , Humanos , Masculino , Estimulação Física , Tempo de Reação/fisiologia , Rotação , Percepção Espacial/fisiologia , Percepção do Tato/fisiologia , Adulto Jovem
4.
Neurocrit Care ; 28(1): 104-109, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28337603

RESUMO

BACKGROUND: Targeted temperature management (TTM) represents the standard of care in comatose survivors after cardiac arrest (CA) and may be applied targeting 33° or 36 °C. While multimodal prognostication has been extensively tested for 33 °C, scarce information exists for 36 °C. METHODS: In this cohort study, consecutive comatose adults after CA treated with TTM at 36 °C between July 2014 and October 2016 were included. A combination of neurological examination, electrophysiological features, and serum neuron-specific enolase (NSE) was evaluated for outcome prediction at 3 months (mortality; good outcome defined as cerebral performance categories (CPC) score of 1-2, poor outcome defined as CPC 3-5). RESULTS: We analyzed 61 patients. The presence of two or more predictors out of, unreactive electroencephalogram (EEG) background, epileptiform EEG, absent pupillary and/or corneal reflex, early myoclonus, bilaterally absent cortical somatosensory evoked potentials, and serum NSE >75 µg/l, had a high specificity for predicting mortality (positive predictive value [PPV] = 1.00, 95% CI 0.87-1.00) and poor outcome (PPV = 1.00, 95% CI 0.80-1.00). Reactive EEG background was highly sensitive for predicting good outcome (0.95, 95% CI 0.74-0.99). CONCLUSIONS: Prediction of outcome after CA and TTM targeting 36 °C seems valid in adults using the same features tested at 33 °C. A reactive EEG under TTM appears highly sensitive for good outcome.


Assuntos
Eletroencefalografia/métodos , Parada Cardíaca , Hipotermia Induzida/métodos , Exame Neurológico/métodos , Avaliação de Resultados em Cuidados de Saúde , Fosfopiruvato Hidratase/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Parada Cardíaca/sangue , Parada Cardíaca/diagnóstico , Parada Cardíaca/fisiopatologia , Parada Cardíaca/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico
5.
J Neurosci ; 36(32): 8453-60, 2016 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-27511016

RESUMO

UNLABELLED: Recent research has investigated self-consciousness associated with the multisensory processing of bodily signals (e.g., somatosensory, visual, vestibular signals), a notion referred to as bodily self-consciousness, and these studies have shown that the manipulation of bodily inputs induces changes in bodily self-consciousness such as self-identification. Another line of research has highlighted the importance of signals from the inside of the body (e.g., visceral signals) and proposed that neural representations of internal bodily signals underlie self-consciousness, which to date has been based on philosophical inquiry, clinical case studies, and behavioral studies. Here, we investigated the relationship of bodily self-consciousness with the neural processing of internal bodily signals. By combining electrical neuroimaging, analysis of peripheral physiological signals, and virtual reality technology in humans, we show that transient modulations of neural responses to heartbeats in the posterior cingulate cortex covary with changes in bodily self-consciousness induced by the full-body illusion. Additional analyses excluded that measured basic cardiorespiratory parameters or interoceptive sensitivity traits could account for this finding. These neurophysiological data link experimentally the cortical mapping of the internal body to self-consciousness. SIGNIFICANCE STATEMENT: What are the brain mechanisms of self-consciousness? Prominent views propose that the neural processing associated with signals from the internal organs (such as the heart and the lung) plays a critical role in self-consciousness. Although this hypothesis dates back to influential views in philosophy and psychology (e.g., William James), definitive experimental evidence supporting this idea is lacking despite its recent impact in neuroscience. In the present study, we show that posterior cingulate activities responding to heartbeat signals covary with changes in participants' conscious self-identification with a body that were manipulated experimentally using virtual reality technology. Our finding provides important neural evidence about the long-standing proposal that self-consciousness is linked to the cortical processing of internal bodily signals.


Assuntos
Imagem Corporal , Mapeamento Encefálico , Encéfalo/fisiologia , Estado de Consciência/fisiologia , Frequência Cardíaca/fisiologia , Autoimagem , Adulto , Eletrocardiografia , Eletroencefalografia , Feminino , Análise de Fourier , Humanos , Ilusões/fisiologia , Masculino , Inquéritos e Questionários , Adulto Jovem
6.
Neuroimage ; 158: 176-185, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28669917

RESUMO

Multisensory perception research has largely focused on exteroceptive signals, but recent evidence has revealed the integration of interoceptive signals with exteroceptive information. Such research revealed that heartbeat signals affect sensory (e.g., visual) processing: however, it is unknown how they impact the perception of body images. Here we linked our participants' heartbeat to visual stimuli and investigated the spatio-temporal brain dynamics of cardio-visual stimulation on the processing of human body images. We recorded visual evoked potentials with 64-channel electroencephalography while showing a body or a scrambled-body (control) that appeared at the frequency of the on-line recorded participants' heartbeat or not (not-synchronous, control). Extending earlier studies, we found a body-independent effect, with cardiac signals enhancing visual processing during two time periods (77-130 ms and 145-246 ms). Within the second (later) time-window we detected a second effect characterised by enhanced activity in parietal, temporo-occipital, inferior frontal, and right basal ganglia-insula regions, but only when non-scrambled body images were flashed synchronously with the heartbeat (208-224 ms). In conclusion, our results highlight the role of interoceptive information for the visual processing of human body pictures within a network integrating cardio-visual signals of relevance for perceptual and cognitive aspects of visual body processing.


Assuntos
Interocepção/fisiologia , Percepção Visual/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados Visuais/fisiologia , Feminino , Coração , Humanos , Masculino , Estimulação Luminosa/métodos , Processamento de Sinais Assistido por Computador , Adulto Jovem
7.
Blood ; 125(5): 820-30, 2015 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-25428221

RESUMO

Patients with t(1;19)-positive acute lymphoblastic leukemia (ALL) are prone to central nervous system (CNS) relapses, and expression of the TAM (Tyro3, Axl, and Mer) receptor Mer is upregulated in these leukemias. We examined the functional role of Mer in the CNS in preclinical models and performed correlative studies in 64 t(1;19)-positive and 93 control pediatric ALL patients. ALL cells were analyzed in coculture with human glioma cells and normal rat astrocytes: CNS coculture caused quiescence and protection from methotrexate toxicity in Mer(high) ALL cell lines, which was antagonized by short hairpin RNA-mediated knockdown of Mer. Mer expression was upregulated, prosurvival Akt and mitogen-activated protein kinase signaling were activated, and secretion of the Mer ligand Galectin-3 was stimulated. Mer(high) t(1;19) primary cells caused CNS involvement to a larger extent in murine xenografts than in their Mer(low) counterparts. Leukemic cells from Mer(high) xenografts showed enhanced survival in coculture. Treatment of Mer(high) patient cells with the Mer-specific inhibitor UNC-569 in vivo delayed leukemia onset, reduced CNS infiltration, and prolonged survival of mice. Finally, a correlation between high Mer expression and CNS positivity upon initial diagnosis was observed in t(1;19) patients. Our data provide evidence that Mer is associated with survival in the CNS in t(1;19)-positive ALL, suggesting a role as a diagnostic marker and therapeutic target.


Assuntos
Sistema Nervoso Central/metabolismo , Regulação Leucêmica da Expressão Gênica , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteínas Proto-Oncogênicas/genética , Pirazóis/uso terapêutico , Pirimidinas/uso terapêutico , Receptores Proteína Tirosina Quinases/genética , Animais , Antimetabólitos Antineoplásicos/farmacologia , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Proteínas Sanguíneas , Estudos de Casos e Controles , Sobrevivência Celular , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/patologia , Criança , Cromossomos Humanos Par 1 , Cromossomos Humanos Par 19 , Técnicas de Cocultura , Feminino , Galectina 3/genética , Galectina 3/metabolismo , Galectinas , Glioma/genética , Glioma/metabolismo , Glioma/patologia , Humanos , Metotrexato/farmacologia , Camundongos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Cultura Primária de Células , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Translocação Genética , Células Tumorais Cultivadas , c-Mer Tirosina Quinase
8.
Neuroimage ; 125: 208-219, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26466979

RESUMO

In non-human primates several brain areas contain neurons that respond to both vestibular and somatosensory stimulation. In humans, vestibular stimulation activates several somatosensory brain regions and improves tactile perception. However, less is known about the spatio-temporal dynamics of such vestibular-somatosensory interactions in the human brain. To address this issue, we recorded high-density electroencephalography during left median nerve electrical stimulation to obtain Somatosensory Evoked Potentials (SEPs). We analyzed SEPs during vestibular activation following sudden decelerations from constant-velocity (90°/s and 60°/s) earth-vertical axis yaw rotations and SEPs during a non-vestibular control period. SEP analysis revealed two distinct temporal effects of vestibular activation: An early effect (28-32ms post-stimulus) characterized by vestibular suppression of SEP response strength that depended on rotation velocity and a later effect (97-112ms post-stimulus) characterized by vestibular modulation of SEP topographical pattern that was rotation velocity-independent. Source estimation localized these vestibular effects, during both time periods, to activation differences in a distributed cortical network including the right postcentral gyrus, right insula, left precuneus, and bilateral secondary somatosensory cortex. These results suggest that vestibular-somatosensory interactions in humans depend on processing in specific time periods in somatosensory and vestibular cortical regions.


Assuntos
Potenciais Somatossensoriais Evocados/fisiologia , Córtex Somatossensorial/fisiologia , Vestíbulo do Labirinto/fisiologia , Adulto , Estimulação Elétrica , Eletroencefalografia , Feminino , Humanos , Masculino , Rotação , Transdução de Sinais/fisiologia , Adulto Jovem
9.
Exp Brain Res ; 232(12): 4021-33, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25200173

RESUMO

Self-consciousness is based on multisensory signals from the body. In full-body illusion (FBI) experiments, multisensory conflict was used to induce changes in three key aspects of bodily self-consciousness (BSC): self-identification (which body 'I' identify with), self-location (where 'I' am located), and first-person perspective (from where 'I' experience the world; 1PP). Here, we adapted a previous FBI protocol in which visuotactile stroking was administered by a robotic device (tactile stroking) and simultaneously rendered on the back of a virtual body (visual stroking) that participants viewed on a head-mounted display as if filmed from a posterior viewpoint of a camera. We compared the effects of two different visuospatial viewpoints on the FBI and thereby on these key aspects of BSC. During control manipulations, participants saw a no-body object instead of a virtual body (first experiment) or received asynchronous versus synchronous visuotactile stroking (second experiment). Results showed that within-subjects visuospatial viewpoint manipulations affected the subjective 1PP ratings if a virtual body was seen but had no effect for viewing a non-body object. However, visuospatial viewpoint had no effect on self-identification, but depended on the viewed object and visuotactile synchrony. Self-location depended on visuospatial viewpoint (first experiment) and visuotactile synchrony (second experiment). Our results show that the visuospatial viewpoint from which the virtual body is seen during FBIs modulates the subjective 1PP and that such viewpoint manipulations contribute to spatial aspects of BSC. We compare the present data with recent data revealing vestibular contributions to the subjective 1PP and discuss the multisensory nature of BSC and the subjective 1PP.


Assuntos
Ilusões/fisiologia , Autoimagem , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Ilusões/psicologia , Masculino , Estimulação Luminosa , Adulto Jovem
10.
Commun Biol ; 7(1): 226, 2024 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-38396068

RESUMO

The human brain can encode auditory regularities with fixed sound-to-sound intervals and with sound onsets locked to cardiac inputs. Here, we investigated auditory and cardio-audio regularity encoding during sleep, when bodily and environmental stimulus processing may be altered. Using electroencephalography and electrocardiography in healthy volunteers (N = 26) during wakefulness and sleep, we measured the response to unexpected sound omissions within three regularity conditions: synchronous, where sound and heartbeat are temporally coupled, isochronous, with fixed sound-to-sound intervals, and a control condition without regularity. Cardio-audio regularity encoding manifested as a heartbeat deceleration upon omissions across vigilance states. The synchronous and isochronous sequences induced a modulation of the omission-evoked neural response in wakefulness and N2 sleep, the former accompanied by background oscillatory activity reorganization. The violation of cardio-audio and auditory regularity elicits cardiac and neural responses across vigilance states, laying the ground for similar investigations in altered consciousness states such as coma and anaesthesia.


Assuntos
Eletroencefalografia , Vigília , Humanos , Vigília/fisiologia , Sono/fisiologia , Encéfalo/fisiologia , Som
11.
Small ; 9(9-10): 1573-84, 2013 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-23112130

RESUMO

The innovative use of engineered nanomaterials in medicine, be it in therapy or diagnosis, is growing dramatically. This is motivated by the current extraordinary control over the synthesis of complex nanomaterials with a variety of biological functions (e.g. contrast agents, drug-delivery systems, transducers, amplifiers, etc.). Engineered nanomaterials are found in the bio-context with a variety of applications in fields such as sensing, imaging, therapy or diagnosis. As the degree of control to fabricate customized novel and/or enhanced nanomaterials evolves, often new applications, devices with enhanced performance or unprecedented sensing limits can be achieved. Of course, interfacing any novel material with biological systems has to be critically analyzed as many undesirable adverse effects can be triggered (e.g. toxicity, allergy, genotoxicity, etc.) and/or the performance of the nanomaterial can be compromised due to the unexpected phenomena in physiological environments (e.g. corrosion, aggregation, unspecific absorption of biomolecules, etc.). Despite the need for standard protocols for assessing the toxicity and bio-performance of each new functional nanomaterial, these are still scarce or currently under development. Nonetheless, nanotoxicology and relating adverse effects to the physico-chemical properties of nanomaterials are emerging areas of the utmost importance which have to be continuously revisited as any new material emerges. This review highlights recent progress concerning the interaction of nanomaterials with biological systems and following adverse effects.


Assuntos
Nanopartículas , Sistemas de Liberação de Medicamentos , Transferência Ressonante de Energia de Fluorescência , Humanos , Nanopartículas/efeitos adversos , Nanopartículas/toxicidade
12.
Sci Rep ; 13(1): 9727, 2023 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-37322248

RESUMO

Does gravity affect decision-making? This question comes into sharp focus as plans for interplanetary human space missions solidify. In the framework of Bayesian brain theories, gravity encapsulates a strong prior, anchoring agents to a reference frame via the vestibular system, informing their decisions and possibly their integration of uncertainty. What happens when such a strong prior is altered? We address this question using a self-motion estimation task in a space analog environment under conditions of altered gravity. Two participants were cast as remote drone operators orbiting Mars in a virtual reality environment on board a parabolic flight, where both hyper- and microgravity conditions were induced. From a first-person perspective, participants viewed a drone exiting a cave and had to first predict a collision and then provide a confidence estimate of their response. We evoked uncertainty in the task by manipulating the motion's trajectory angle. Post-decision subjective confidence reports were negatively predicted by stimulus uncertainty, as expected. Uncertainty alone did not impact overt behavioral responses (performance, choice) differentially across gravity conditions. However microgravity predicted higher subjective confidence, especially in interaction with stimulus uncertainty. These results suggest that variables relating to uncertainty affect decision-making distinctly in microgravity, highlighting the possible need for automatized, compensatory mechanisms when considering human factors in space research.


Assuntos
Gravidade Alterada , Voo Espacial , Ausência de Peso , Humanos , Teorema de Bayes , Incerteza , Encéfalo
13.
Cortex ; 161: 116-144, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36933455

RESUMO

Increasing life expectancy is prompting the need to understand how the brain changes during healthy aging. Research utilizing electroencephalography (EEG) has found that the power of alpha oscillations decrease from adulthood on. However, non-oscillatory (aperiodic) components in the data may confound results and thus require re-investigation of these findings. Thus, the present report analyzed a pilot and two additional independent samples (total N = 533) of resting-state EEG from healthy young and elderly individuals. A newly developed algorithm was utilized that allows the decomposition of the measured signal into periodic and aperiodic signal components. By using multivariate sequential Bayesian updating of the age effect in each signal component, evidence across the datasets was accumulated. It was hypothesized that previously reported age-related alpha power differences will largely diminish when total power is adjusted for the aperiodic signal component. First, the age-related decrease in total alpha power was replicated. Concurrently, decreases of the intercept and slope (i.e. exponent) of the aperiodic signal component were observed. Findings on aperiodic-adjusted alpha power indicated that this general shift of the power spectrum leads to an overestimation of the true age effects in conventional analyses of total alpha power. Thus, the importance of separating neural power spectra into periodic and aperiodic signal components is highlighted. However, also after accounting for these confounding factors, the sequential Bayesian updating analysis provided robust evidence that aging is associated with decreased aperiodic-adjusted alpha power. While the relation of the aperiodic component and aperiodic-adjusted alpha power to cognitive decline demands further investigation, the consistent findings on age effects across independent datasets and high test-retest reliabilities support that these newly emerging measures are reliable markers of the aging brain. Hence, previous interpretations of age-related decreases in alpha power are reevaluated, incorporating changes in the aperiodic signal.


Assuntos
Disfunção Cognitiva , Eletroencefalografia , Humanos , Adulto , Idoso , Teorema de Bayes , Encéfalo , Envelhecimento
14.
Psychophysiology ; 60(7): e14268, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-36894751

RESUMO

The quantification of resting-state electroencephalography (EEG) is associated with a variety of measures. These include power estimates at different frequencies, microstate analysis, and frequency-resolved source power and connectivity analyses. Resting-state EEG metrics have been widely used to delineate the manifestation of cognition and to identify psychophysiological indicators of age-related cognitive decline. The reliability of the utilized metrics is a prerequisite for establishing robust brain-behavior relationships and clinically relevant indicators of cognitive decline. To date, however, test-retest reliability examination of measures derived from resting human EEG, comparing different resting-state measures between young and older participants, within the same adequately powered dataset, is lacking. The present registered report examined test-retest reliability in a sample of 95 young (age range: 20-35 years) and 93 older (age range: 60-80 years) participants. A good-to-excellent test-retest reliability was confirmed in both age groups for power estimates on both scalp and source levels as well as for the individual alpha peak power and frequency. Partial confirmation was observed for hypotheses stating good-to-excellent reliability of microstates measures and connectivity. Equal levels of reliability between the age groups were confirmed for scalp-level power estimates and partially so for source-level power and connectivity. In total, five out of the nine postulated hypotheses were empirically supported and confirmed good-to-excellent reliability of the most commonly reported resting-state EEG metrics.


Assuntos
Encéfalo , Eletroencefalografia , Humanos , Idoso , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso de 80 Anos ou mais , Reprodutibilidade dos Testes , Encéfalo/fisiologia , Mapeamento Encefálico , Couro Cabeludo
15.
Langmuir ; 28(24): 8915-9, 2012 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-22444199

RESUMO

Ultrasmall water-soluble silver nanoclusters are synthesized, and their properties are investigated. The silver nanoclusters have high colloidal stability and show fluorescence in the red. This demonstrates that like gold nanoclusters also silver nanoclusters can be fluorescent.


Assuntos
Fluorescência , Nanopartículas Metálicas/química , Prata/química , Coloides/síntese química , Coloides/química , Tamanho da Partícula , Propriedades de Superfície
16.
BMC Public Health ; 12: 263, 2012 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-22469235

RESUMO

BACKGROUND: As epidemiological surveys have shown, binge drinking is a constant and wide-spread problem behavior in adolescents. It is not rare to find that more than half of all adolescents engage in this behavior when assessing only the last 4 weeks of time independent of the urbanity of the region they live in. There have been several reviews on predictors of substance consumption in adolescents in general, but there has been less high quality research on predictors of binge drinking, and most studies have not been theoretically based. The current study aimed to analyze the ultimate and distal factors predicting substance consumption according to Petraitis' theory of triadic influence. We assessed the predictive value of these factors with respect to binge drinking in German adolescents, including the identification of influence direction. METHODS: In the years 2007/2008, a representative written survey of N = 44,610 students in the 9th grade of different school types in Germany was carried out (net sample). The return rate of questionnaires was 88% regarding all students whose teachers or school directors had agreed to participate in the study. In this survey, prevalence of binge drinking was investigated as well as potential predictors from the social/interpersonal, the attitudinal/environmental, and the intrapersonal fields (3 factors of Petraitis). In a multivariate logistic regression analysis, these variables were included after testing for multicollinearity in order to assess their ability to predict binge drinking. RESULTS: Prevalence of binge drinking in the last 30 days was 52.3% for the surveyed adolescents with a higher prevalence for boys (56.9%) than for girls (47.5%). The two most influential factors found to protect against binge drinking with p < .001 were low economic status and importance of religion. The four most relevant risk factors for binge drinking (p < .001) were life-time prevalence of school absenteeism/truancy, academic failure, suicidal thoughts, and violence at school in the form of aggressive behavior of teachers. The model of Petraitis was partly confirmed for Binge Drinking in German adolescents and the direction of influence factors was clarified. CONCLUSIONS: Whereas some of the risk and protective factors for binge drinking are not surprising since they are known for substance abuse in general, there are two points that could be targeted in interventions that do not focus on adolescents alone: (a) training teachers in positive, reassuring behavior and constructive criticism and (b) a focus on high risk adolescents either because they have a lack of coping strategies when in a negative mood or because of their low academic achievement in combination with absenteeism from school.


Assuntos
Alcoolismo/etiologia , Etanol/intoxicação , Adolescente , Comportamento do Adolescente , Alcoolismo/epidemiologia , Coleta de Dados , Feminino , Previsões , Alemanha/epidemiologia , Humanos , Modelos Logísticos , Masculino , Razão de Chances , Fatores de Risco
17.
PLoS One ; 17(3): e0264471, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35231038

RESUMO

Humans race drones faster than neural networks trained for end-to-end autonomous flight. This may be related to the ability of human pilots to select task-relevant visual information effectively. This work investigates whether neural networks capable of imitating human eye gaze behavior and attention can improve neural networks' performance for the challenging task of vision-based autonomous drone racing. We hypothesize that gaze-based attention prediction can be an efficient mechanism for visual information selection and decision making in a simulator-based drone racing task. We test this hypothesis using eye gaze and flight trajectory data from 18 human drone pilots to train a visual attention prediction model. We then use this visual attention prediction model to train an end-to-end controller for vision-based autonomous drone racing using imitation learning. We compare the drone racing performance of the attention-prediction controller to those using raw image inputs and image-based abstractions (i.e., feature tracks). Comparing success rates for completing a challenging race track by autonomous flight, our results show that the attention-prediction based controller (88% success rate) outperforms the RGB-image (61% success rate) and feature-tracks (55% success rate) controller baselines. Furthermore, visual attention-prediction and feature-track based models showed better generalization performance than image-based models when evaluated on hold-out reference trajectories. Our results demonstrate that human visual attention prediction improves the performance of autonomous vision-based drone racing agents and provides an essential step towards vision-based, fast, and agile autonomous flight that eventually can reach and even exceed human performances.


Assuntos
Redes Neurais de Computação , Dispositivos Aéreos não Tripulados , Fixação Ocular , Humanos , Visão Ocular
18.
BMC Public Health ; 11: 84, 2011 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-21299841

RESUMO

BACKGROUND: Binge drinking is a constant problem behavior in adolescents across Europe. Epidemiological investigations have been reported. However, epidemiological data on alcohol consumption of adolescents with different migration backgrounds are rare. Furthermore representative data on rural-urban comparison concerning alcohol consumption and binge drinking are lacking. The aims of the study are the investigation of alcohol consumption patterns with respect to a) urban-rural differences and b) differences according to migration background. METHODS: In the years 2007/2008, a representative written survey of N = 44,610 students in the 9th. grade of different school types in Germany was carried out (net sample). The return rate of questionnaires was 88% regarding all students whose teachers respectively school directors had agreed to participate in the study. Weighting factors were specified and used to make up for regional and school-type specific differences in return rates. 27.4% of the adolescents surveyed have a migration background, whereby the Turkish culture is the largest group followed by adolescents who emigrated from former Soviet Union states. The sample includes seven large cities (over 500,000 inhabitants) (12.2%), independent smaller cities ("urban districts") (19.0%) and rural areas ("rural districts") (68.8%). RESULTS: Life-time prevalence for alcohol consumption differs significantly between rural (93.7%) and urban areas (86.6% large cities; 89.1% smaller cities) with a higher prevalence in rural areas. The same accounts for 12-month prevalence for alcohol consumption. 57.3% of the rural, respectively 45.9% of the urban adolescents engaged in binge drinking in the 4 weeks prior to the survey. Students with migration background of the former Soviet Union showed mainly drinking behavior similar to that of German adolescents. Adolescents with Turkish roots had engaged in binge drinking in the last four weeks less frequently than adolescents of German descent (23.6% vs. 57.4%). However, in those adolescents who consumed alcohol in the last 4 weeks, binge drinking is very prominent across the cultural backgrounds. CONCLUSIONS: Binge drinking is a common problem behavior in German adolescents. Obviously adolescents with rural residence have fewer alternatives for engaging in interesting leisure activities than adolescents living in cities. This might be one reason for the more problematic consumption patterns there. Common expectations concerning drinking behavior of adolescents of certain cultural backgrounds ('migrants with Russian background drink more'/'migrants from Arabic respectively Oriental-Islamic countries drink less') are only partly affirmed. Possibly, the degree of acculturation to the permissive German alcohol culture plays a role here.


Assuntos
Consumo de Bebidas Alcoólicas/epidemiologia , Alcoolismo/epidemiologia , Emigrantes e Imigrantes , População Rural , População Urbana , Adolescente , Consumo de Bebidas Alcoólicas/etnologia , Alcoolismo/etnologia , Feminino , Alemanha/epidemiologia , Inquéritos Epidemiológicos , Humanos , Masculino , Federação Russa/etnologia , Turquia/etnologia
19.
Br J Dev Psychol ; 28(Pt 3): 699-725, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20849041

RESUMO

In work done at the German Criminological Research Institute of Lower Saxony (KFN) various methods have been used to investigate how specific inappropriate media usage patterns affect academic performance in children and adolescents. The findings are paralleled by current international research indicating a negative relationship between these two variables. Based on a cross-sectional survey of 5,529 fourth grade students and a longitudinal panel study with 1,157 primary schoolchildren, a key finding can be demonstrated: the more time students spend on consuming media and the more violent its contents are, the worse are their marks at school, even when controlling for vital factors such as family, educational, or immigrant background. In particular, boys who gender-specifically are better equipped with electronic media devices, who partially have extensive media usage times and who strongly prefer violent media content, are at the risk of showing poor school performance. In fact, a decrease in academic performance of boys can be observed in German school statistics. By presenting first results of a school-based intervention programme, a promising approach to the reduction of detrimental effects of electronic media use on school performance is introduced.


Assuntos
Logro , Atividades de Lazer , Microcomputadores , Televisão , Jogos de Vídeo , Alcoolismo/psicologia , Transtorno da Personalidade Antissocial/psicologia , Estudos Transversais , Alemanha , Inquéritos Epidemiológicos , Humanos , Delinquência Juvenil/psicologia , Fatores de Risco , Fatores Sexuais , Socialização , Transtornos Relacionados ao Uso de Substâncias/psicologia , Fatores de Tempo , Violência/psicologia
20.
eNeuro ; 7(5)2020.
Artigo em Inglês | MEDLINE | ID: mdl-32907833

RESUMO

Neuropsychological studies indicate that healthy aging is associated with a decline of inhibitory control of attentional and behavioral systems. A widely accepted measure of inhibitory control is the antisaccade task that requires both the inhibition of a reflexive saccadic response toward a visual target and the initiation of a voluntary eye movement in the opposite direction. To better understand the nature of age-related differences in inhibitory control, we evaluated antisaccade task performance in 78 younger (20-35 years) and 78 older (60-80 years) participants. In order to provide reliable estimates of inhibitory control for individual subjects, we investigated test-retest reliability of the reaction time, error rate, saccadic gain, and peak saccadic velocity and further estimated latent, not directly observable processed contributing to changes in the antisaccade task execution. The intraclass correlation coefficients (ICCs) for an older group of participants emerged as good to excellent for most of our antisaccade task measures. Furthermore, using Bayesian multivariate models, we inspected age-related differences in the performances of healthy younger and older participants. The older group demonstrated higher error rates, longer reaction times, significantly more inhibition failures, and late prosaccades as compared with young adults. The consequently lower ability of older adults to voluntarily inhibit saccadic responses has been interpreted as an indicator of age-related inhibitory control decline. Additionally, we performed a Bayesian model comparison of used computational models and concluded that the Stochastic Early Reaction, Inhibition and Late Action (SERIA) model explains our data better than PRO-Stop-Antisaccade (PROSA) that does not incorporate a late decision process.


Assuntos
Envelhecimento , Movimentos Sacádicos , Adulto , Idoso , Teorema de Bayes , Humanos , Tempo de Reação , Reprodutibilidade dos Testes , Adulto Jovem
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