Bottom-up Pathways Research Articles

Cortical Mapping in Conventional and High Dose Spinal Cord Stimulation: An Exploratory Power Spectrum and Functional Connectivity Analysis With Electroencephalography

Spinal cord stimulation (SCS) is considered an effective pain-relieving treatment for patients with Failed Back Surgery Syndrome (FBSS). Despite the clinical effectiveness, it is unknown whether the altered functional connectivity in such patients, as compared to healthy persons, can be influenced by SCS. Therefore, the goal of this study is to evaluate whether brain connectivity assessed by EEG differs between baseline and SCS in patients with FBSS. Eight patients with FBSS underwent a resting-state EEG protocol before SCS, 1.5 months and 2.5 months after receiving SCS. At each frequency band, power spectrums were compared for no SCS, conventional (CON) SCS and High Dose (HD) SCS. Functional connectivity, with the aid of eConnectome was also calculated. Significant differences in the average power density spectrum over the whole scalp were observed between no SCS, CON SCS and HD SCS in delta, theta and beta frequency bands (p < 0.01). The average power spectrum for CON SCS was significantly lower than the average power spectrum for HD SCS. Marked increases in strength of the information flow between electrode pair FC3-TP9 in the beta frequency band (p = 0.006) were found in favor of HD SCS. The differences in power spectrum and connectivity between the three conditions lead to the hypothesis that HD SCS differs from CON SCS on average power spectrum, suggesting that HD SCS may have a higher contribution on the excitatory bottom-up pathway.

Corrections to “Ensemble of Instance Segmentation Models for Polyp Segmentation in Colonoscopy Images”

In the above-named article, we explored the ensemble model using two Mask R-CNNs with the backbones consisting of ResNet50 and ResNet101, respectively, for polyp segmentation in colonoscopy images. The proposed ensemble method has two main stages. First, it generates proposals of the regions where there might be an object based on the given input image. Second, it predicts the class of the object, refines the bounding box, and finally generates a mask in the pixel level of the object based on the first stage proposal. Both stages are connected to the backbone structure. Backbone is a Feature Pyramid Network (FPN) style deep neural network. It consists of a bottom-up pathway, a top-bottom pathway, and lateral connections. AlexNet, VGG, Inception-ResNet-v2, ResNet50, and ResNet101 are some of the popular backbone networks.

A Differential Circuit via Retino-Colliculo-Pulvinar Pathway Enhances Feature Selectivity in Visual Cortex through Surround Suppression

In the mammalian visual system, information from the retina streams into parallel bottom-up pathways. It remains unclear how these pathways interact to contribute to contextual modulation of visual cortical processing. By optogenetic inactivation and activation of mouse lateral posterior nucleus (LP) of thalamus, a homolog of pulvinar, or its projection to primary visual cortex (V1), we found that LP contributes to surround suppression of layer (L) 2/3 responses in V1 by driving L1 inhibitory neurons. This results in subtractive suppression of visual responses and an overall enhancement of orientation, direction, spatial, and size selectivity. Neurons in V1-projecting LP regions receive bottom-up input from the superior colliculus (SC) and respond preferably to non-patterned visual noise. The noise-dependent LP activity allows V1 to "cancel" noise effects and maintain its orientation selectivity under varyingnoise background. Thus, the retina-SC-LP-V1 pathway forms a differential circuit with the canonical retino-geniculate pathway to achieve context-dependent sharpening of visual representations.

Physiological processes of inflammation and edema initiated by sustained mechanical loading in subcutaneous tissues: A scoping review.

Deep tissue injuries are pressure ulcers which initiate in the subcutaneous tissues and extend through a bottom-up pathway. Once deep tissue injuries are visual at skin level, serious irreversible tissue damage has already occurred. In pressure ulcer development, inflammation and edema are coupled physiological processes associated with tissue damage arising due to sustained mechanical loading. This study aimed to provide an in-depth overview of the physiological processes of inflammation and edema initiated by sustained mechanical loading in subcutaneous tissues, in the context of pressure ulceration. A scoping review was performed according to the framework by Arksey and O'Malley. The databases MEDLINE, EMBASE, Web of Science, and Scopus, and the reference lists of included studies were searched for in vivo (animal, human), and in vitro studies matching the study objectives (from inception to 28 May 2018). No restrictions for inclusion were applied for study design, setting, participants, and year of publication. A total of 12 studies were included, varying in study design, sample characteristics, amount and duration of mechanical loads that were applied, follow-up time, and assessment methods. Neutrophil infiltration and edema occur in the subcutaneous tissues nearly immediately after the application of load on soft tissues. The amount of neutrophils and edema increase in the first days after the mechanical insult and decrease once healing has been initiated and no supplementary mechanical load was applied. One study indicated that edema may extend up to the level of the dermo-epidermal junction. Further research should focus on how deep tissue inflammation and edema are reflected into unique tissue changes at skin level, and how abnormal inflammatory responses manifest (e.g. when the nervous system is not functioning normally).

CircleNet: Reciprocating Feature Adaptation for Robust Pedestrian Detection

Pedestrian detection in the wild remains a challenging problem especially when the scene contains significant occlusion and/or low resolution of the pedestrians to be detected. Existing methods are unable to adapt to these difficult cases while maintaining acceptable performance. In this paper we propose a novel feature learning model, referred to as CircleNet, to achieve feature adaptation by mimicking the process humans looking at low resolution and occluded objects: focusing on it again, at a finer scale, if the object can not be identified clearly for the first time. CircleNet is implemented as a set of feature pyramids and uses weight sharing path augmentation for better feature fusion. It targets at reciprocating feature adaptation and iterative object detection using multiple top-down and bottom-up pathways. To take full advantage of the feature adaptation capability in CircleNet, we design an instance decomposition training strategy to focus on detecting pedestrian instances of various resolutions and different occlusion levels in each cycle. Specifically, CircleNet implements feature ensemble with the idea of hard negative boosting in an end-to-end manner. Experiments on two pedestrian detection datasets, Caltech and CityPersons, show that CircleNet improves the performance of occluded and low-resolution pedestrians with significant margins while maintaining good performance on normal instances.

Indian Imaginaries of Chinese Success in the Global Herbal Medicine Market

Abstract India’s share in the global herbal market is dwarfed by that of China. Public and policy discourse in India exhorts Ayurvedic stakeholders to emulate Chinese medicine’s “science-based approach” to expand their global market share. But contrary to popular perception in India, China has been largely unsuccessful in making inroads into the coveted Euro-American herbal medicine market. Chinese medicine’s global footprint is largely the result of historical-cultural links, diasporic influences, and acupuncture practitioners. With national traditional medicine policies increasingly shaped by the evidence-based regulatory paradigm, the future of these informal bottom-up pathways is uncertain. Ignoring the roots of Chinese medicine’s global career has led to a distorted image of its “success” as an outcome of state investment in scientific validation and standardization programs. Our findings underscore the need to critically examine the imaginaries of success that drive stakeholders of non-biomedical traditions toward scientization to earn legitimacy and profits in the global realm.

Invasive Japanese Barberry, Berberis thunbergii (Ranunculales: Berberidaceae) Is Associated With Simplified Branch-Dwelling and Leaf-Litter Arthropod Communities in a New York Forest.

Arthropod food webs can be indirectly impacted by woody plant invasions, with cascading consequences for higher trophic levels. There are multiple bottom-up pathways by which invasive plants can alter food webs: above-ground interactions based on plant-herbivore associations and below-ground at the interface of leaf-litter and soil food webs. We compared arthropod community composition in these two food web dimensions in a New York forest that has been heavily invaded by nonnative Japanese barberry. Using two sampling protocols, we compared arthropod community composition on Japanese barberry shrubs to multiple species of native host shrubs and then compared leaf-litter arthropod assemblages between forest patches with exceptionally high Japanese barberry densities and those with relatively little to no Japanese barberry present. Fitting with trends in other woody shrub invasions, arthropod species richness was significantly lower in the leaf litter around Japanese barberry and on Japanese barberry plants themselves. Although overall arthropod abundance was also significantly lower on and in the leaf litter around Japanese barberry than on and around native shrubs, total biomass did not differ due to the taxa associated with Japanese barberry tending to be larger-bodied. We observed a dramatic reduction in predatory arthropods in response to both bottom-up pathways, particularly among ants and spiders. Our results show that Japanese barberry-invaded habitats may be experiencing trophic downgrading as result of lower numbers of generalist predators like spiders and ants, which may have rippling effects up the food web to insectivorous animals and their predators.

Gated bidirectional feature pyramid network for accurate one-shot detection

Despite recent advances in machine learning, it is still challenging to realize real-time and accurate detection in images. The recently proposed StairNet detector (Sanghyun et al. in Proceedings of winter conference on applications of computer vision (WACV), 2018), one of the strongest one-stage detectors, tackles this issue by using a SSD in conjunction with a top-down enrichment module. However, the StairNet approach misses the finer localization information which can be obtained from the lower layer and lacks a feature selection mechanism, which can lead to suboptimal features during the merging step. In this paper, we propose what is termed the gated bidirectional feature pyramid network (GBFPN), a simple and effective architecture that provides a significant improvement over the baseline model, StairNet. The overall network is composed of three parts: a bottom-up pathway, a top-down pathway, and a gating module. Given the multi-scale feature pyramid of deep convolutional network, two separate pathways introduce both finer localization cues and high-level semantics. In each pathway, the gating module dynamically re-weights the features before the combining step, transmitting only the informative features. Placing GBFPN on top of a basic one-stage detector SSD, our method shows state-of-the-art results.

Neural processing of odor-associated words: an fMRI study in patients with acquired olfactory loss.

Perception of olfactory information is mediated by both bottom-up (from molecules to perception) and top-down (e.g. cross-modal associative learning) processes. Acquired olfactory loss is a frequent disorder which is typically due to alterations in the bottom-up pathway. However, it is unclear how the top-down modulation of olfactory processing is affected by olfactory impairment. Our study aimed to investigate the top-down olfactory processing in patients with acquired olfactory loss and participants with normal olfaction. Using functional MRI, brain responses from 14 patients and 16 healthy controls were assessed during a task of expectation and reading of words with strong olfactory associations (OW) (e.g. "Rose") and control words with little to no olfactory associations (CW) (e.g. "Door"). The expectation but not reading of the OW was associated with stronger neural activation in the angular gyrus and the inferior frontal gyrus extending to insula in the group of patients. During OW reading, the brain activation in the left OFC and right putamen was negatively correlated with odor identification score in patient and control groups, respectively. In addition, the duration of olfactory loss among patients was positively associated with activation in the left putamen during OW expectation. Taken together, these findings suggest an enhanced top-down olfactory modulation in patients with olfactory loss.

Responses of seed size, ant worker size, and seed removal rate to elevation in Mediterranean grasslands.

Elevational gradients are a powerful tool to investigate how abiotic factors affect ecosystems and to predict the possible consequences of climate change. Here, we investigated the assemblage-level responses of seed size, ant worker size, and rates of seed removal by ants along a 1700m elevational gradient in Mediterranean grasslands of central Spain, taking into account abiotic factors and interactions between biotic variables. Our results showed that both seed size and ant size decreased with elevation. Structural equation models linking abiotic factors and biotic variables were built to describe these patterns. Two equally plausible models were selected, both based on temperature. In the first model, temperature directly affected seed size and granivorous ant size, and indirectly affected ant size (of both granivorous and non-granivorous species) through a bottom-up pathway. The second model included the direct effects of temperature on ant size and granivorous ant size, and indirect effects on seed size through a top-down pathway. In this model, the link between granivorous ant size and seed size was positive. Seed removal rates decreased with elevation and seed size, with smaller seeds being preferred with increasing elevation. Taken together, our results indicate that the observed patterns of ant size and seed size are ultimately controlled by abiotic factors, although the system is more satisfactorily explained if seed-ant interactions are incorporated into the models. We expect that climate change will have strong effects on this system, including mismatches between consumers and producers potentially altering the interspecific relationships among ants and plants.

Abstract # 3115 Chemotherapy, bacterial translocation, heart rate variability, and depression in breast cancer survivors

While psychosocial factors are powerful predictors of depression in cancer patients, objective measures (e.g., chemotherapy treatment length and type) have been inconsistently linked to depression. Even so, several studies have found higher rates of depression among chemotherapy patients. The kynurenine pathway has been proposed as an inflammation-mediated link between chemotherapy and depression. The current study proposed and tested another pathway from chemotherapy to depression. Breast cancer survivors (N = 143) were recruited for the parent study – a yoga clinical trial. At the baseline visit, women had blood drawn, completed the CES-d, and engaged in relaxation while heart rate variability (HRV) was measured. Chemotherapy patients (n = 87) had greater serum CD14 (p = 0.032), an index of bacterial translocation and intestinal permeability. Additionally, women with higher levels of serum CD14 exhibited lower HRV (p = 0.049) – consistent with mechanistic animal studies. Finally, lower HRV was associated with greater depressive symptoms (p = 0.018). A double mediation model was tested, with chemotherapy leading to serum CD14 leading to HRV leading to depressive symptoms. Controlling for age, sagittal abdominal diameter, beta blocker use, tamoxifen, and radiation, a complete mediation emerged, whereby women who received chemotherapy had greater depressive symptoms when both serum CD14 and heart rate variability were included as mediators (CI: 0.0043–0.4690). Results suggest a novel bottom-up pathway from chemotherapy to depression.

On Biomineralization: Enzymes Switch on Mesocrystal Assembly

Cellular machineries guide the bottom-up pathways toward crystal superstructures based on the transport of inorganic precursors and their precise integration with organic frameworks. The biosynthesis of mesocrystalline spines entails concerted interactions between biomolecules and inorganic precursors; however, the bioinorganic interactions and interfaces that regulate material form and growth as well as the selective emergence of structural complexity in the form of nanostructured crystals are not clear. By investigating mineral nucleation under the regulation of recombinant proteins, we show that SpSM50, a matrix protein of the sea urchin spine, stabilizes mineral precursors via vesicle-confinement, a function conferred by a low-complexity, disordered region. Site-specific proteolysis of this domain by a collagenase initiates phase transformation of the confined mineral phase. The residual C-type lectin domain molds the fluidic mineral precursor into hierarchical mesocrystals identical to structural crystal modules constituting the biogenic mineral. Thus, the regulatory functions of proteolytic enzymes can guide biomacromolecular domain constitutions and interfaces, in turn determining inorganic phase transformations toward hybrid materials as well as integrating organic and inorganic components across hierarchical length scales. Bearing striking resemblance to biogenic mineralization, these hybrid materials recruit bioinorganic interactions which elegantly intertwine nucleation and crystallization phenomena with biomolecular structural dynamics, hence elucidating a long-sought key of how nature can orchestrate complex biomineralization processes.

Public Appeal and Local Fiscal Transparency：An Empirical Analysis based on Chinese Provincial Panel Data

Fiscal transparency is not only the basic feature of the modern fiscal budget system, but also the inevitable requirement of establishing a sunshine and responsibility government. Fiscal transparency means disclosing to the public the structure, functions, public sector accounts, fiscal forecast information, etc., and ensuring that the information is timely, detailed, reliable and understandable. If local governments lack sufficient impetus to improve local financial transparency, it is clearly worth studying whether to improve local financial transparency through the bottom-up pathway. What is more, with the official implementation of the Regulation of Government Information Disclosure in 2008, public concern and enthusiasm for public information openness issues have gradually increased. At the central government level, the number of applications for information disclosure accepted by the ministry of finance increased from 17 to 1,362 in 2008-2014. At the local government level, the number of applications for fiscal information disclosure received by provincial departments of finance in China fluctuates slightly, but generally shows an upward trend. From 2008 to 2015, the provincial department of finance received 149, 222, 912, 558, 834, 892, 880 and 1616 government information disclosure applications respectively. The public’s application to local governments for fiscal information disclosure involves the three public consumptions”, the social security” information, the public pricing information and many other aspects. Based on these observations and reflections, this paper uses the panel data of 31 provinces in China from 2011 to 2015 to analyze the mechanism of public appeal for local fiscal transparency. We first use Baidu search function to structure the index which can measure the public attention on fiscal transparency problem index in different provinces and different years, then analyze the public demands for the influence of local total fiscal transparency. On this basis, we analyze the public demands for state-owned enterprise information transparency, the transparency of the social security fund and the general public budget transparency further. At the same time, there may be significant regional differences in the influence of public appeal on local fiscal transparency in coastal areas and inland areas. Therefore, we examine the regional differences between coastal areas and inland areas in which public appeal affects local fiscal transparency. Our empirical results show that the public’s focus on the three public consumption” issues will promote the fiscal transparency of the local government, the transparency of state-owned enterprises and the transparency of the social security fund. The public’s focus on social security” will promote the fiscal transparency of local government and the transparency of state-owned enterprises. However, public attention will not promote the general public budget transparency. At the same time, in coastal areas, the public’s attention to the three public consumptions” and the social security” information can significantly promote the total fiscal transparency of local governments. However, in inland areas, public appeal does not significantly affect local fiscal transparency, whether it concerns the three public consumptions” or the social security” information.

The gut-brain axis: interactions between microbiota and nervous systems

Humans coexist in a mutualistic relationship with the intestinal microbiota, a complex microbial ecosystem that resides largely in the distal bowel. The lower gastrointestinal tract contains almost 100 trillion microorganisms, most of which are bacteria. More than 1,000 bacterial species have been identified in this microbiota. The intestinal microbiota lives in a symbiotic relationship with the host. A bidirectional neurohumoral communication system, known as the gut–brain axis, integrates the host gut and brain activities (Mayer et al. 2015). Communication between the brain and gut occurs along a network of pathways collectively termed the brain-gut axis. The brain-gut axis encompass the CNS, ENS, sympathetic and parasympathetic branches of the autonomic nervous system, neuroendocrine and neuroimmune pathways, and the gut microbiota (Colins et al. 2012). The gut microbiota can signal to the brain via a number of pathways which include: regulating immune activity and the production of roinflammatory cytokines that can either stimulate the HPA axis to produce CRH, ACTH and cortisol, or directly impact on CNS immune activity; through the production of SCFAs such as propionate, butyrate, and acetate; the production of neurotransmitters which may enter circulation and cross the blood brain barrier; by modulating tryptophan metabolism and downstream metabolites, serotonin, kynurenic acid and quinolinic acid. Neuronal and spinal pathways, particularly afferent signaling pathways of the vagus nerve, are critical in mediating the effect of the gut microbiota on brain function and behavior. Microbial produced SCFAs and indole also impact on EC cells of the enteric nervous system (Romijn et al. 2008; Cani et al. 2013). The purpose of this presentation was to summarize our current knowledge regarding the role of microbiota in bottom-up pathways of communication in the gutbrain axis.

Canopy closure after four decades of postlogging riparian forest regeneration reduces cutthroat trout biomass in headwater streams through bottom-up pathways

Recovery from timber harvest is widespread across North America, but few studies have evaluated long-term stream responses to riparian harvest. We revisited five stream reach pairs where in 1976, periphyton chlorophyll a, predatory invertebrate biomass, and cutthroat trout (Oncorhynchus clarkii clarkii) biomass were elevated in reaches where canopies were more open following timber harvest. After four decades of riparian regeneration, mean canopy openness, chlorophyll a, predatory invertebrate biomass, and cutthroat trout biomass declined in harvested reaches relative to paired old-growth reference reaches. In one reach pair, the harvested reach remained more open than the control reach. In accordance with the hypothesis that light exerts strong controls on predator biomass via bottom-up processes in these forested headwaters, trout biomass was also greater in the harvested reach in this pair in 2014. Changes in large wood and pool area over this time interval do not account for chlorophyll a, predatory invertebrate biomass, or cutthroat trout biomass responses. These results provide empirical support for conceptual models relating changes in riparian canopy cover to primary production and bottom-up controls on consumer populations.

Artifacts and Errors Associated with the Ubiquitous Presence of Fluorescent Impurities in Carbon Nanodots

Fluorescent carbon dots have attracted tremendous attention owing to their superlative optical properties which suggest opportunities for replacing conventional fluorescent materials in various application fields. Not surprisingly, the rapid pace of publication has been accompanied by a host of critical issues, errors, controversies, and misconceptions associated with these emergent materials, which present significant barriers to elucidating their true nature, substantially hindering the extensive exploitation of these nanomaterials. Of particular interest are expedient, bottom-up pathways to carbon dots starting from molecular precursors (e.g., citric acid, amino acids, and alkylamines), although such routes are associated with generation of a ubiquity of small molecular weight or oligomeric fluorescent byproducts. A primary obstacle to progress is the inadequacy of purification in reported studies, an omission which gives rise to misconceptions about the nature and characteristics of the carbon dots. I...

Strong Functional Connectivity among Homotopic Brain Areas Is Vital for Motor Control in Unilateral Limb Movement.

The mechanism underlying brain region organization for motor control in humans remains poorly understood. In this functional magnetic resonance imaging (fMRI) study, right-handed volunteers were tasked to maintain unilateral foot movements on the right and left sides as consistently as possible. We aimed to identify the similarities and differences between brain motor networks of the two conditions. We recruited 18 right-handed healthy volunteers aged 25 ± 2.3 years and used a whole-body 3T system for magnetic resonance (MR) scanning. Image analysis was performed using SPM8, Conn toolbox and Brain Connectivity Toolbox. We determined a craniocaudally distributed, mirror-symmetrical modular structure. The functional connectivity between homotopic brain areas was generally stronger than the intrahemispheric connections, and such strong connectivity led to the abovementioned modular structure. Our findings indicated that the interhemispheric functional interaction between homotopic brain areas is more intensive than the interaction along the conventional top–down and bottom–up pathways within the brain during unilateral limb movement. The detected strong interhemispheric horizontal functional interaction is an important aspect of motor control but often neglected or underestimated. The strong interhemispheric connectivity may explain the physiological phenomena and effects of promising therapeutic approaches. Further accurate and effective therapeutic methods may be developed on the basis of our findings.

(Invited) Molecular-Scale Evidence Provides New Insights into Fullerene Formation Mechanism

It has been proposed that the fullerene formation mechanism involves either a top-down or bottom-up pathway. Despite of different starting points, either mechanism approved that particular fullerenes or metallofullerenes are formed through a consecutive stepwise process involving Stone-Wales transformations (SWTs) and C2 insertion or extrusion. However, the formation pathway has been seldom defined at the molecular level due to the missing link fullerenes. Herein, we present a series of previously missing species, including Sc2O@C2v(24107)-C78 and Sc2O@D3h(24109)-C78, Sc2O@C2(7892)-C70 and Sc2C2@D3h(14246)-C74. Each of them can be converted to other isomers or larger or smaller species via a simple conversion route involving Stone-Wales (SW) transformation and C2 insertion or extrusion. Thus, this study might provide molecular structural evidence for the less confirmed fullerene formation mechanism.

Solvothermal fabrication and growth behavior study of spherical MnFe2O4 through a bottom-up method on wood substrate with effective microwave absorption

Spherical MnFe2O4 colloidal nanocrystal assemblies (CNAs) with different sizes were controllably fabricated on a wood substrate using a solvothermal method through a bottom-up pathway.

Declines in benthic macroinvertebrate community metrics and microphytobenthic biomass in an estuarine lake following enrichment by hippo dung.

Hippos transfer massive quantities of trophic resources from terrestrial to aquatic ecosystems through defecation. The ramifications of the latter for the functioning of benthic ecosystems are unknown, but are dependent ultimately on rates of utilisation relative to inputs. Low input and high utilisation can strengthen bottom-up pathways and enhance consumer biomass and abundance. However, if inputs exceed utilisation rates, dung can accumulate, leading to a decline in water quality, with important repercussions for resident assemblages. Here, we quantify the consequences of hippo dung inputs on benthic assemblages in an estuarine lake in South Africa. The system supports over a thousand hippos, and during recent drought periods (extending over a decade), hippo dung has been observed to form mats over benthic habitats. Enrichment of plots using exclusion/inclusion cages with dung at naturally occurring concentrations indicated a decline in benthic chl-a by roughly 50% and macrofaunal abundance, biomass and richness by up to 76, 56 and 27% respectively. Our findings suggest that persistent inputs of hippo dung can act as an important stressor of benthic systems, leading ultimately to a loss of productivity. Accumulation of hippo dung over benthic habitats is therefore an important mechanism by which hippos indirectly structure aquatic ecosystems.