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https://www.readbyqxmd.com/read/27932957/emergence-of-selectivity-to-looming-stimuli-in-a-spiking-network-model-of-the-optic-tectum
#1
Eric V Jang, Carolina Ramirez-Vizcarrondo, Carlos D Aizenman, Arseny S Khakhalin
The neural circuits in the optic tectum of Xenopus tadpoles are selectively responsive to looming visual stimuli that resemble objects approaching the animal at a collision trajectory. This selectivity is required for adaptive collision avoidance behavior in this species, but its underlying mechanisms are not known. In particular, it is still unclear how the balance between the recurrent spontaneous network activity and the newly arriving sensory flow is set in this structure, and to what degree this balance is important for collision detection...
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27930778/melanopsin-containing-or-non-melanopsin-containing-retinal-ganglion-cells-response-to-acute-ocular-hypertension-with-or-without-brain-derived-neurotrophic-factor-neuroprotection
#2
Giuseppe Rovere, Francisco M Nadal-Nicolás, Jiawei Wang, Jose M Bernal-Garro, Nuria García-Carrillo, Maria Paz Villegas-Pérez, Marta Agudo-Barriuso, Manuel Vidal-Sanz
Purpose: To analyze the responses of different retinal ganglion cell (RGC) types to acute ocular hypertension (AOH) and intravitreal administration of brain-derived neurotrophic factor (BDNF). Methods: In adult albino rats, the anterior chamber of the left eye was cannulated with a needle connected to a saline container elevated 1½ meters above the eye for 75 minutes. Rats received 12 hours before a 5 μl intravitreal injection containing 5 μg BDNF in 1% albumin PBS or vehicle and were analyzed 3, 7, 14, or 45 days later...
December 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27929102/functional-connectivity-changes-resemble-patterns-of-ptdp-43-pathology-in-amyotrophic-lateral-sclerosis
#3
Ines Schulthess, Martin Gorges, Hans-Peter Müller, Dorothée Lulé, Kelly Del Tredici, Albert C Ludolph, Jan Kassubek
'Resting-state' fMRI allows investigation of alterations in functional brain organization that are associated with an underlying pathological process. We determine whether abnormal connectivity in amyotrophic lateral sclerosis (ALS) in a priori-defined intrinsic functional connectivity networks, according to a neuropathological staging scheme and its DTI-based tract correlates, permits recognition of a sequential involvement of functional networks. 'Resting-state' fMRI data from 135 ALS patients and 56 matched healthy controls were investigated for the motor network (corresponding to neuropathological stage 1), brainstem (stage 2), ventral attention (stage 3), default mode/hippocampal network (stage 4), and primary visual network (as the control network) in a cross-sectional analysis and longitudinally in a subgroup of 27 patients after 6 months...
December 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27928035/quantifying-species-contributions-to-ecosystem-processes-a-global-assessment-of-functional-trait-and-phylogenetic-metrics-across-avian-seed-dispersal-networks
#4
Alexander L Pigot, Tom Bregman, Catherine Sheard, Benjamin Daly, Rampal S Etienne, Joseph A Tobias
Quantifying the role of biodiversity in ecosystems not only requires understanding the links between species and the ecological functions and services they provide, but also how these factors relate to measurable indices, such as functional traits and phylogenetic diversity. However, these relationships remain poorly understood, especially for heterotrophic organisms within complex ecological networks. Here, we assemble data on avian traits across a global sample of mutualistic plant-frugivore networks to critically assess how the functional roles of frugivores are associated with their intrinsic traits, as well as their evolutionary and functional distinctiveness...
December 14, 2016: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/27924003/the-combination-of-direct-and-paired-link-graphs-can-boost-repetitive-genome-assembly
#5
Wenyu Shi, Peifeng Ji, Fangqing Zhao
Currently, most paired link based scaffolding algorithms intrinsically mask the sequences between two linked contigs and bypass their direct link information embedded in the original de Bruijn assembly graph. Such disadvantage substantially complicates the scaffolding process and leads to the inability of resolving repetitive contig assembly. Here we present a novel algorithm, inGAP-sf, for effectively generating high-quality and continuous scaffolds. inGAP-sf achieves this by using a new strategy based on the combination of direct link and paired link graphs, in which direct link is used to increase graph connectivity and to decrease graph complexity and paired link is employed to supervise the traversing process on the direct link graph...
December 6, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27920729/transcriptional-network-architecture-of-breast-cancer-molecular-subtypes
#6
Guillermo de Anda-Jáuregui, Tadeo E Velázquez-Caldelas, Jesús Espinal-Enríquez, Enrique Hernández-Lemus
Breast cancer heterogeneity is evident at the clinical, histological and molecular level. High throughput technologies allowed the identification of intrinsic subtypes that capture transcriptional differences among tumors. A remaining question is whether said differences are associated to a particular transcriptional program which involves different connections between the same molecules. In other words, whether particular transcriptional network architectures can be linked to specific phenotypes. In this work we infer, construct and analyze transcriptional networks from whole-genome gene expression microarrays, by using an information theory approach...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27918910/altered-dynamics-of-brain-connectivity-in-major-depressive-disorder-at-rest-and-during-task-performance
#7
Fabio Sambataro, Eleonora Visintin, Nadja Doerig, Janis Brakowski, Martin Grosse Holtforth, Erich Seifritz, Simona Spinelli
Major depressive disorder (MDD) has been associated with alterations in several functional brain networks. Previous studies investigating brain networks in MDD during the performance of a task have yielded inconsistent results with the function of the brain at rest. In this study, we used functional magnetic resonance imaging at rest and during a goal-directed task to investigate dynamics of functional connectivity in 19 unmedicated patients with MDD and 19 healthy controls across both experimental paradigms...
November 17, 2016: Psychiatry Research
https://www.readbyqxmd.com/read/27917569/distinct-intrinsic-functional-brain-network-abnormalities-in-methamphetamine-dependent-patients-with-and-without-a-history-of-psychosis
#8
Jonathan C Ipser, Anne Uhlmann, Paul Taylor, Brian H Harvey, Don Wilson, Dan J Stein
Chronic methamphetamine use is associated with executive functioning deficits that suggest dysfunctional cognitive control networks (CCNs) in the brain. Likewise, abnormal connectivity between intrinsic CCNs and default mode networks (DMNs) has also been associated with poor cognitive function in clinical populations. Accordingly, we tested the extent to which methamphetamine use predicts abnormal connectivity between these networks, and whether, as predicted, these abnormalities are compounded in patients with a history of methamphetamine-associated psychosis (MAP)...
December 5, 2016: Addiction Biology
https://www.readbyqxmd.com/read/27917138/neural-elements-for-predictive-coding
#9
REVIEW
Stewart Shipp
Predictive coding theories of sensory brain function interpret the hierarchical construction of the cerebral cortex as a Bayesian, generative model capable of predicting the sensory data consistent with any given percept. Predictions are fed backward in the hierarchy and reciprocated by prediction error in the forward direction, acting to modify the representation of the outside world at increasing levels of abstraction, and so to optimize the nature of perception over a series of iterations. This accounts for many 'illusory' instances of perception where what is seen (heard, etc...
2016: Frontiers in Psychology
https://www.readbyqxmd.com/read/27913586/local-circuits-of-v1-layer-4b-neurons-projecting-to-v2-thick-stripes-define-distinct-cell-classes-and-avoid-cytochrome-oxidase-blobs
#10
Jeff Yarch, Frederick Federer, Alessandra Angelucci
: Decades of anatomical studies on the primate primary visual cortex (V1) have led to a detailed diagram of V1 intrinsic circuitry, but this diagram lacks information about the output targets of V1 cells. Understanding how V1 local processing relates to downstream processing requires identification of neuronal populations defined by their output targets. In primates, V1 layers (L)2/3 and 4B send segregated projections to distinct cytochrome oxidase (CO) stripes in area V2: neurons in CO blob-columns project to thin stripes, and those outside blob columns to thick and pale stripes, suggesting functional specialization of V1-to-V2 CO streams...
December 2, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27913359/network-unfolding-map-by-vertex-edge-dynamics-modeling
#11
Filipe Alves Neto Verri, Paulo Roberto Urio, Liang Zhao
The emergence of collective dynamics in neural networks is a mechanism of the animal and human brain for information processing. In this paper, we develop a computational technique using distributed processing elements in a complex network, which are called particles, to solve semisupervised learning problems. Three actions govern the particles' dynamics: generation, walking, and absorption. Labeled vertices generate new particles that compete against rival particles for edge domination. Active particles randomly walk in the network until they are absorbed by either a rival vertex or an edge currently dominated by rival particles...
November 29, 2016: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/27910222/cyclic-vomiting-syndrome-is-characterized-by-altered-functional-brain-connectivity-of-the-insular-cortex-a-cross-comparison-with-migraine-and-healthy-adults
#12
D-M Ellingsen, R G Garcia, J Lee, R L Lin, J Kim, A H Thurler, S Castel, L Dimisko, B R Rosen, N Hadjikhani, B Kuo, V Napadow
Cyclic Vomiting Syndrome (CVS) has been linked to episodic migraine, yet little is known about the precise brain-based mechanisms underpinning CVS, and whether these associated conditions share similar pathophysiology. We investigated the functional integrity of salience (SLN) and sensorimotor (SMN) intrinsic connectivity networks in CVS, migraine and healthy controls using brain functional Magnetic Resonance Imaging. CVS, relative to both migraine and controls, showed increased SLN connectivity to middle/posterior insula, a key brain region for nausea and viscerosensory processing...
December 1, 2016: Neurogastroenterology and Motility: the Official Journal of the European Gastrointestinal Motility Society
https://www.readbyqxmd.com/read/27909841/the-shaping-of-intrinsic-membrane-potential-oscillations-positive-negative-feedback-ionic-resonance-amplification-nonlinearities-and-time-scales
#13
Horacio G Rotstein
The generation of intrinsic subthreshold (membrane potential) oscillations (STOs) in neuronal models requires the interaction between two processes: a relatively fast positive feedback that favors changes in voltage and a slower negative feedback that opposes these changes. These are provided by the so-called resonant and amplifying gating variables associated to the participating ionic currents. We investigate both the biophysical and dynamic mechanisms of generation of STOs and how their attributes (frequency and amplitude) depend on the model parameters for biophysical (conductance-based) models having qualitatively different types of resonant currents (activating and inactivating) and an amplifying current...
December 1, 2016: Journal of Computational Neuroscience
https://www.readbyqxmd.com/read/27909483/from-incidental-mechanically-induced-arrhythmias-to-reflex-defined-arrhythmogenicity-on-the-track-of-the-ternary-reflex-system-resemblance-to-the-infancy-of-new-era-or-rediscovery
#14
REVIEW
Petras Stirbys Md PhD
The underlying pathophysiology of supraventricular and ventricular arrhythmias remains a matter of intense investigation. Though evolving, the contemporary explanations do not encompass all aspects of arrhythmogenicity. An improved understanding of arrhythmia substrate is needed to augment therapeutic capabilities. Our observation and literature sources demonstrate relatively high incidence of transitory arrhythmias which are non-intentionally generated by the endocardial lead/catheter manipulation. These findings are interesting and potentially may crystallize the reflex-dependent proarrhythmic cardiac activity...
February 2016: Journal of Atrial Fibrillation
https://www.readbyqxmd.com/read/27907060/amplitude-of-low-frequency-fluctuation-alff-in-the-cervical-spinal-cord-with-stenosis-a-resting-state-fmri-study
#15
Xiaojia Liu, Wenshu Qian, Richu Jin, Xiang Li, Keith Dk Luk, Ed X Wu, Yong Hu
Cervical spondylotic myelopathy (CSM) is a common spinal cord dysfunction disease with complex symptoms in clinical presentation. Resting state fMRI (rsfMRI) has been introduced to study the mechanism of neural development of CSM. However, most of those studies focused on intrinsic functional connectivity rather than intrinsic regional neural activity level which is also frequently analyzed in rsfMRI studies. Thus, this study aims to explore whether the level of neural activity changes on the myelopathic cervical cord and evaluate the possible relationship between this change and clinical symptoms through amplitude of low frequency fluctuation (ALFF)...
2016: PloS One
https://www.readbyqxmd.com/read/27903719/the-segregation-and-integration-of-distinct-brain-networks-and-their-relationship-to-cognition
#16
Jessica R Cohen, Mark D'Esposito
: A critical feature of the human brain that gives rise to complex cognition is its ability to reconfigure its network structure dynamically and adaptively in response to the environment. Existing research probing task-related reconfiguration of brain network structure has concluded that, although there are many similarities in network structure during an intrinsic, resting state and during the performance of a variety of cognitive tasks, there are meaningful differences as well. In this study, we related intrinsic, resting state network organization to reconfigured network organization during the performance of two tasks: a sequence tapping task, which is thought to probe motor execution and likely engages a single brain network, and an n-back task, which is thought to probe working memory and likely requires coordination across multiple networks...
November 30, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27902696/interglomerular-connectivity-within-the-canonical-and-gc-d-necklace-olfactory-subsystems
#17
Cedric R Uytingco, Adam C Puche, Steven D Munger
The mammalian main olfactory system contains several subsystems that differ not only in the receptors they express and the glomerular targets they innervate within the main olfactory bulb (MOB), but also in the strategies they use to process odor information. The canonical main olfactory system employs a combinatorial coding strategy that represents odorant identity as a pattern of glomerular activity. By contrast, the "GC-D/necklace" olfactory subsystem-formed by olfactory sensory neurons expressing the receptor guanylyl cyclase GC-D and their target necklace glomeruli (NGs) encircling the caudal MOB-is critical for the detection of a small number of semiochemicals that promote the acquisition of food preferences...
2016: PloS One
https://www.readbyqxmd.com/read/27901115/p53-coordinates-dna-repair-with-nucleotide-synthesis-by-suppressing-pfkfb3-expression-and-promoting-the-pentose-phosphate-pathway
#18
Derek A Franklin, Yizhou He, Patrick L Leslie, Andrey P Tikunov, Nick Fenger, Jeffrey M Macdonald, Yanping Zhang
Activation of p53 in response to DNA damage is essential for tumor suppression. Although previous studies have emphasized the importance of p53-dependent cell cycle arrest and apoptosis for tumor suppression, recent studies have suggested that other areas of p53 regulation, such as metabolism and DNA damage repair (DDR), are also essential for p53-dependent tumor suppression. However, the intrinsic connections between p53-mediated DDR and metabolic regulation remain incompletely understood. Here, we present data suggesting that p53 promotes nucleotide biosynthesis in response to DNA damage by repressing the expression of the phosphofructokinase-2 (PFK2) isoform 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), a rate-limiting enzyme that promotes glycolysis...
November 30, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27897189/a-design-principle-of-polymers-processable-into-2d-homeotropic-order
#19
Zhen Chen, Yi-Tsu Chan, Daigo Miyajima, Takashi Kajitani, Atsuko Kosaka, Takanori Fukushima, Jose M Lobez, Takuzo Aida
How to orient polymers homeotropically in thin films has been a long-standing issue in polymer science because polymers intrinsically prefer to lie down. Here we provide a design principle for polymers that are processable into a 2D homeotropic order. The key to this achievement was a recognition that cylindrical polymers can be designed to possess oppositely directed local dipoles in their cross-section, which possibly force polymers to tightly connect bilaterally, affording a 2D rectangular assembly. With a physical assistance of the surface grooves on Teflon sheets that sandwich polymer samples, homeotropic ordering is likely nucleated and gradually propagates upon hot-pressing towards the interior of the film...
November 29, 2016: Nature Communications
https://www.readbyqxmd.com/read/27897151/effect-of-intermittent-hypoxic-training-on-hypoxia-tolerance-based-on-brain-functional-connectivity
#20
Guang Li, Tinglin Zhang, Xiaojian Chen, Chungang Shang, You Wang
The difference of brain functional connectivity between hypoxic and normal states was studied. The impact of intermittent hypoxic training on the hypoxia tolerance of the brain was explored. Multivariable empirical mode decomposition was applied to extract common inherent modes of multichannel EEG adaptively instead of a priori selection of filter bandwidth, and the first two scales of intrinsic mode functions expressed the differences in brain connectivity. To quantify synchronization and search for consistent performance, coherence, phase locking value and synchronization likelihood were all utilized...
November 29, 2016: Physiological Measurement
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