scholarly journals Bottom-up sensory processing can decrease activity and functional connectivity in the default mode like network in rats

2018 ◽  
Author(s):  
Rukun Hinz ◽  
Lore M. B. Peeters ◽  
Disha Shah ◽  
Stephan Missault ◽  
Michaël Belloy ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Sensory Processing ◽  
Large Scale ◽  
Visual Stimulation ◽  
Block Design ◽  
Brain State ◽  
Top Down ◽  
Similar Reduction ◽  
Bottom Up ◽  
Default Mode

AbstractThe default mode network is a large-scale brain network that is active during rest and internally focused states and deactivates as well as desynchronizes during externally oriented (top-down) attention demanding cognitive tasks. However, it is not sufficiently understood if unpredicted salient stimuli, able to trigger bottom-up attentional processes, could also result in similar reduction of activity and functional connectivity in the DMN. In this study, we investigated whether bottom-up sensory processing could influence the default mode like network (DMLN) in rats. DMLN activity was examined using block-design visual functional magnetic resonance imaging (fMRI) while its synchronization was investigated by comparing functional connectivity during a resting versus a continuously stimulated brain state by unpredicted light flashes. We demonstrated that activity in DMLN regions was decreased during visual stimulus blocks and increased during blanks. Furthermore, decreased inter-network functional connectivity between the DMLN and visual networks as well as decreased intra-network functional connectivity within the DMLN was observed during the continuous visual stimulation. These results suggest that triggering of bottom-up attention mechanisms in anesthetized rats can lead to a cascade similar to top-down orienting of attention in humans and is able to deactivate and desynchronize the DMLN.

scholarly journals Bottom-up sensory processing can induce negative BOLD responses and reduce functional connectivity in nodes of the default mode-like network in rats

NeuroImage ◽  
2019 ◽  
Vol 197 ◽  
pp. 167-176 ◽  
Author(s):  
Rukun Hinz ◽  
Lore M. Peeters ◽  
Disha Shah ◽  
Stephan Missault ◽  
Michaël Belloy ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Sensory Processing ◽  
Bottom Up ◽  
Default Mode ◽  
Bold Responses ◽  
Negative Bold

“Forward to David the Builder!” Georgia's (re)turn to language-centered nationalism

2016 ◽  
Vol 44 (4) ◽  
pp. 522-542 ◽  
Author(s):  
Christofer Berglund
Keyword(s):  
Large Scale ◽  
Nation Building ◽  
The State ◽  
Top Down ◽  
Bottom Up ◽  
The Past ◽  
Building Project ◽  
The Rose ◽  
State Language

After the Rose Revolution, President Saakashvili tried to move away from the exclusionary nationalism of the past, which had poisoned relations between Georgians and their Armenian and Azerbaijani compatriots. His government instead sought to foster an inclusionary nationalism, wherein belonging was contingent upon speaking the state language and all Georgian speakers, irrespective of origin, were to be equals. This article examines this nation-building project from a top-down and bottom-up lens. I first argue that state officials took rigorous steps to signal that Georgian-speaking minorities were part of the national fabric, but failed to abolish religious and historical barriers to their inclusion. I next utilize a large-scale, matched-guise experiment (n= 792) to explore if adolescent Georgians ostracize Georgian-speaking minorities or embrace them as their peers. I find that the upcoming generation of Georgians harbor attitudes in line with Saakashvili's language-centered nationalism, and that current Georgian nationalism therefore is more inclusionary than previous research, or Georgia's tumultuous past, would lead us to believe.

scholarly journals Climate Dialog, Climate Action: Can Democracy Do the Job?

2021 ◽  
Author(s):  
Fred Young Phillips ◽  
LaVonne Reimer ◽  
Rebecca Turner
Keyword(s):  
Large Scale ◽  
Global Climate ◽  
Environmental Issues ◽  
Top Down ◽  
Bottom Up ◽  
Psychological Mechanisms ◽  
Ipcc Report ◽  
Climate Action

The latest IPCC report forcefully states that immediate, decisive, and large-scale actions are needed to avert climate catastrophe. This essay presumes that democratic governments are best and most desirably positioned to take these actions. Yet in the countries most pivotal to global climate, significant voting blocs are uninterested in environmental issues. The essay urges adding bottom-up dialog between environmental and anti-environmental voters, to current and future top-down technocratic “solutions.” To make this combination result in a unified pro-environment electorate, we must understand: religious objections to environmentalism; the capital-vs.-knowledge strife that slows polluting corporations’ green transitions; and the psychological mechanisms that can make inter-group dialog fruitful.

Attentional Fluctuations Influence the Neural Fidelity and Connectivity of Stimulus Representations

2018 ◽  
Vol 30 (9) ◽  
pp. 1209-1228 ◽  
Author(s):  
David Rothlein ◽  
Joseph DeGutis ◽  
Michael Esterman
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Brain Networks ◽  
Relevant Information ◽  
Mental States ◽  
Attention Task ◽  
Default Mode ◽  
Neural Representations ◽  
Similarity Structure ◽  
Similarity Matrices

Attention is thought to facilitate both the representation of task-relevant features and the communication of these representations across large-scale brain networks. However, attention is not “all or none,” but rather it fluctuates between stable/accurate (in-the-zone) and variable/error-prone (out-of-the-zone) states. Here we ask how different attentional states relate to the neural processing and transmission of task-relevant information. Specifically, during in-the-zone periods: (1) Do neural representations of task stimuli have greater fidelity? (2) Is there increased communication of this stimulus information across large-scale brain networks? Finally, (3) can the influence of performance-contingent reward be differentiated from zone-based fluctuations? To address these questions, we used fMRI and representational similarity analysis during a visual sustained attention task (the gradCPT). Participants ( n = 16) viewed a series of city or mountain scenes, responding to cities (90% of trials) and withholding to mountains (10%). Representational similarity matrices, reflecting the similarity structure of the city exemplars ( n = 10), were computed from visual, attentional, and default mode networks. Representational fidelity (RF) and representational connectivity (RC) were quantified as the interparticipant reliability of representational similarity matrices within (RF) and across (RC) brain networks. We found that being in the zone was characterized by increased RF in visual networks and increasing RC between visual and attentional networks. Conversely, reward only increased the RC between the attentional and default mode networks. These results diverge with analogous analyses using functional connectivity, suggesting that RC and functional connectivity in tandem better characterize how different mental states modulate the flow of information throughout the brain.

scholarly journals Emissions of Carbon Tetrachloride (CCl<sub>4</sub>) from Europe

2016 ◽  
Author(s):  
Francesco Graziosi ◽  
Jgor Arduini ◽  
Paolo Bonasoni ◽  
Francesco Furlani ◽  
Umberto Giostra ◽  
...  
Keyword(s):  
Carbon Tetrachloride ◽  
Large Scale ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Scale Production ◽  
Top Down ◽  
Significant Discrepancy ◽  
Bottom Up ◽  
Atmospheric Observations ◽  
Global Emissions

Abstract. Carbon tetrachloride (CCl4) is a long-lived radiatively-active compound able to destroy stratospheric ozone. Due to its inclusion in the Montreal Protocol on Substances that Deplete the Ozone Layer, the last two decades have seen a sharp decrease in its large scale emissive use with a consequent decline of its atmospheric mole fractions. However, the Montreal Protocol restrictions do not apply to the use of carbon tetrachloride as feedstock for the production of other chemicals, implying the risk of fugitive emissions from the industry sector. The occurrence of such unintended emissions is suggested by a significant discrepancy between global emissions as derived by reported production and feedstock usage (bottom-up emissions), and those based on atmospheric observations (top-down emissions). In order to better constrain the atmospheric budget of carbon tetrachloride, several studies based on a combination of atmospheric observations and inverse modelling have been conducted in recent years in various regions of the world. This study is focused on the European scale and based on long-term high-frequency observations at three European sites, combined with a Bayesian inversion methodology. We estimated that average European emissions for 2006–2014 were 2.3 (± 0.8) Gg yr−1, with an average decreasing trend of 7.3 % per year. Our analysis identified France as the main source of emissions over the whole study period, with an average contribution to total European emissions of 25 %. The inversion was also able to allow the localisation of emission "hot-spots" in the domain, with major source areas in Southern France, Central England (UK) and Benelux (Belgium, The Netherlands, Luxembourg), where most of industrial scale production of basic organic chemicals are located. According to our results, European emissions correspond to 4.0 % of global emissions for 2006–2012. Together with other regional studies, our results allow a better constraint of the global budget of carbon tetrachloride and a better quantification of the gap between top-down and bottom-up estimates.

Multi-scale predictions distinctively modulate tone perception in schizophrenia patients with auditory verbal hallucinations

2020 ◽  
Author(s):  
Fuyin Yang ◽  
Hao Zhu ◽  
Lingfang Yu ◽  
Weihong Lu ◽  
Chen Zhang ◽  
...  
Keyword(s):  
Sensory Processing ◽  
Source Monitoring ◽  
Weighting Function ◽  
Sensitivity Index ◽  
Healthy Controls ◽  
Top Down ◽  
Bottom Up ◽  
Multiple Timescales ◽  
Temporal Characteristics ◽  
Auditory Verbal Hallucinations

AbstractsAuditory verbal hallucinations (AVHs) are one of the most pronounced symptoms that manifest the underlying mechanisms of deficits in schizophrenia. Cognitive models postulate that malfunctioned source monitoring incorrectly weights the top-down prediction and bottom-up sensory processing and causes hallucinations. Here, we investigate the featural-temporal characteristics of source monitoring in AVHs. Schizophrenia patients with and without AVHs, and healthy controls identified target tones in noise at the end of tone sequences. Predictions of different timescales were manipulated by either an alternating pattern in the preceding tone sequences, or a repetition between the target tone and the tone immediately before. The sensitivity index, d’, was obtained to assess the modulation of predictions on tone identification. We found that patients with AVHs showed higher d’ when the target tones conformed to the long-term regularity of alternating pattern in the preceding tone sequence than that when the targets were inconsistent with the pattern. Whereas, the short-term regularity of repetitions modulated the tone identification in patients without AVHs. Predictions did not influence tone identification in healthy controls. These findings suggest that malfunctioned source monitoring in AVHs heavily weights predictions to form incorrect perception. The weighting function in source monitoring can extend to the process of basic tonal features, and predictions at multiple timescales differentially modulate perception in different clinical populations. These collaboratively reveal the featural and temporal characteristics of weighting function in source monitoring of AVHs and suggest that the malfunctioned interaction between top-down and bottom-up processes might underlie the development of auditory hallucinations.HighlightsMalfunctioned source monitoring incorrectly weights the top-down prediction and bottom-up sensory processing underlie pathogenesis of auditory verbal hallucinations in schizophrenia.The weighting function in top-down predictions and bottom-up sensory processing can extend to tonal features.Predictions at multiple timescales differentially modulate perception in different clinical schizophrenia populations.

scholarly journals δ-Oscillation Correlates of Anesthesia-induced Unconsciousness in Large-scale Brain Networks of Human Infants

2019 ◽  
Vol 131 (6) ◽  
pp. 1239-1253 ◽  
Author(s):  
Ioannis Pappas ◽  
Laura Cornelissen ◽  
David K. Menon ◽  
Charles B. Berde ◽  
Emmanuel A. Stamatakis
Keyword(s):  
Functional Connectivity ◽  
General Anesthesia ◽  
Information Transfer ◽  
Large Scale ◽  
Aminobutyric Acid ◽  
Brain State ◽  
Whole Brain ◽  
Efficient System ◽  
Median Difference ◽  
Infant Brain

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Functional brain connectivity studies can provide important information about changes in brain-state dynamics during general anesthesia. In adults, γ-aminobutyric acid–mediated agents disrupt integration of information from local to the whole-brain scale. Beginning around 3 to 4 months postnatal age, γ-aminobutyric acid–mediated anesthetics such as sevoflurane generate α-electroencephalography oscillations. In previous studies of sevoflurane-anesthetized infants 0 to 3.9 months of age, α-oscillations were absent, and power spectra did not distinguish between anesthetized and emergence from anesthesia conditions. Few studies detailing functional connectivity during general anesthesia in infants exist. This study’s aim was to identify changes in functional connectivity of the infant brain during anesthesia. Methods A retrospective cohort study was performed using multichannel electroencephalograph recordings of 20 infants aged 0 to 3.9 months old who underwent sevoflurane anesthesia for elective surgery. Whole-brain functional connectivity was evaluated during maintenance of a surgical state of anesthesia and during emergence from anesthesia. Functional connectivity was represented as networks, and network efficiency indices (including complexity and modularity) were computed at the sensor and source levels. Results Sevoflurane decreased functional connectivity at the δ-frequency (1 to 4 Hz) in infants 0 to 3.9 months old when comparing anesthesia with emergence. At the sensor level, complexity decreased during anesthesia, showing less whole-brain integration with prominent alterations in the connectivity of frontal and parietal sensors (median difference, 0.0293; 95% CI, −0.0016 to 0.0397). At the source level, similar results were observed (median difference, 0.0201; 95% CI, −0.0025 to 0.0482) with prominent alterations in the connectivity between default-mode and frontoparietal regions. Anesthesia resulted in fragmented modules as modularity increased at the sensor (median difference, 0.0562; 95% CI, 0.0048 to 0.1298) and source (median difference, 0.0548; 95% CI, −0.0040 to 0.1074) levels. Conclusions Sevoflurane is associated with decreased capacity for efficient information transfer in the infant brain. Such findings strengthen the hypothesis that conscious processing relies on an efficient system of integrated information transfer across the whole brain.

Large scale and cost effective generation of 3D self-supporting oxide nanowire architectures by a top-down and bottom-up combined approach

RSC Advances ◽  
2016 ◽  
Vol 6 (51) ◽  
pp. 45923-45930 ◽  
Author(s):  
Peixun Fan ◽  
Minlin Zhong ◽  
Benfeng Bai ◽  
Guofan Jin ◽  
Hongjun Zhang
Keyword(s):  
Large Scale ◽  
Cost Effective ◽  
Combined Approach ◽  
Top Down ◽  
Bottom Up ◽  
Effective Generation

Large-scale and cost-effective generation of desired 3D self-supporting macro–micronano-nanowire architectures is realized by a top-down and bottom-up combined approach.

scholarly journals Human subsystems of medial temporal lobes extend locally to amygdala nuclei and globally to an allostatic-interoceptive system

2019 ◽  
Author(s):  
Adriana L. Ruiz-Rizzo ◽  
Florian Beissner ◽  
Kathrin Finke ◽  
Hermann J. Müller ◽  
Claus Zimmer ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Local Level ◽  
Resting State Fmri ◽  
Medial Temporal Lobes ◽  
Default Mode ◽  
Temporal Lobes ◽  
Dual Regression ◽  
Slow Activity ◽  
Global Brain

AbstractIn mammals, the hippocampus, entorhinal, perirhinal, and parahippocampal cortices (i.e., core regions of the human medial temporal lobes, MTL) are locally interlaced with the adjacent amygdala nuclei at the structural and functional levels. At the global brain level, the human MTL has been described as part of the default mode network whereas amygdala nuclei as parts of the salience network, with both networks forming collectively a large-scale brain system supporting allostatic-interoceptive functions. We hypothesized (i) that intrinsic functional connectivity of slow activity fluctuations would reveal human MTL subsystems locally extending to the amygdala; and (ii) that these extended local subsystems would be globally embedded in large-scale brain systems supporting allostatic-interoceptive functions. From the resting-state fMRI data of three independent samples of cognitively healthy adults (one main and two replication samples: Ns = 101, 61, and 29, respectively), we analyzed the functional connectivity of fluctuating ongoing BOLD-activity within and outside the amygdala-MTL in a data-driven way using masked independent component and dual-regression analyses. We found that at the local level MTL subsystems extend to the amygdala and are functionally organized along the longitudinal amygdala-MTL axis. These subsystems were characterized by a consistent involvement of amygdala, hippocampus, and entorhinal cortex, but a variable participation of perirhinal and parahippocampal regions. At the global level, amygdala-MTL subsystems selectively connected to salience, thalamic-brainstem, and default mode networks – the major cortical and subcortical parts of the allostatic-interoceptive system. These results provide evidence for integrated amygdala-MTL subsystems in humans, which are embedded within a larger allostatic-interoceptive system.

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