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Brain Source Localization

José R Donoso, Dietmar Schmitz, Nikolaus Maier, Richard Kempter
Hippocampal ripples are involved in memory consolidation, but the mechanisms underlying their generation remain unclear. Models relying on interneuron networks in the CA1 region disagree on the predominant source of excitation to interneurons: either 'direct', via the Schaffer collaterals that provide feedforward input from CA3 to CA1, or 'indirect', via the local pyramidal cells in CA1, which are embedded in a recurrent excitatory-inhibitory network. Here, we used physiologically constrained computational models of basket-cell networks to investigate how they respond to different conditions of transient, noisy excitation...
February 16, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
A Kabbara, H Eid, W El Falou, M Khalil, F Wendling, M Hassan
OBJECTIVE: Emerging evidence shows that cognitive deficits in Alzheimer's disease (AD) are associated with disruptions in brain functional connectivity. Thus, the identification of alterations in AD functional networks has become a topic of increasing interest. However, to what extent AD induces disruption of the balance of local and global information processing in the human brain remains elusive. The main objective of this study is to explore the dynamic topological changes of AD networks in terms of brain network segregation and integration...
February 16, 2018: Journal of Neural Engineering
Kaja K Jasińska, Sosthène Guei
Portable neuroimaging approaches provide new advances to the study of brain function and brain development with previously inaccessible populations and in remote locations. This paper shows the development of field functional Near Infrared Spectroscopy (fNIRS) imaging to the study of child language, reading, and cognitive development in a rural village setting of Côte d'Ivoire. Innovation in methods and the development of culturally appropriate neuroimaging protocols allow a first-time look into the brain's development and children's learning outcomes in understudied environments...
February 2, 2018: Journal of Visualized Experiments: JoVE
Yang Qiao, Joy Gumin, Christopher MacLellan, Feng Gao, Richard Bouchard, Frederick Lang, R Jason Stafford, Marites P Melancon
To evaluate the feasibility of visualizing bone marrow-derived human mesenchymal stem cells (MSCs) labeled with a gold-coated magnetic resonance (MR)-active multifunctional nanoparticle (SPIO@Au) for assessing the extent of MSC homing in glioma- bearing mice following carotid artery MSC injection. MATERIALS AND METHODS: Nanoparticle containing superparamagnetic iron oxide coated with gold (SPIO@Au) having a diameter of ~82 nm and maximum absorbance in the near infrared (NIR) region was synthesized...
February 13, 2018: Nanotechnology
Keith P Johnson, Lei Zhao, Daniel Kerschensteiner
The spike trains of retinal ganglion cells (RGCs) are the only source of visual information to the brain. Here, we genetically identify an RGC type in mice that functions as a pixel encoder and increases firing to light increments (PixON-RGC). PixON-RGCs have medium-sized dendritic arbors and non-canonical center-surround receptive fields. From their receptive field center, PixON-RGCs receive only excitatory input, which encodes contrast and spatial information linearly. From their receptive field surround, PixON-RGCs receive only inhibitory input, which is temporally matched to the excitatory center input...
February 6, 2018: Cell Reports
Somayeh Raiesdana
An automated sleep staging based on analyzing long-range time correlations in EEG is proposed. These correlations, indicating time-scale invariant property or self-similarity at different time scales, are known to be salient dynamical characteristics of stage succession for a sleeping brain even when the subject suffers a destructive disorder such as Obstructive Sleep Apnea (OSA). The goal is to extract a set of complementary features from cerebral sources mapped onto the scalp electrodes or from a number of denoised EEG channels...
February 8, 2018: Australasian Physical & Engineering Sciences in Medicine
Forooz Shahbazi Avarvand, Sarah Bartz, Christina Andreou, Wojciech Samek, Gregor Leicht, Christoph Mulert, Andreas K Engel, Guido Nolte
We propose a new method for the localization of nonlinear cross-frequency coupling in EEG and MEG data analysis, based on the estimation of bicoherences at the source level. While for the analysis of rhythmic brain activity, source directions are commonly chosen to maximize power, we suggest to maximize bicoherence instead. The resulting nonlinear cost function can be minimized effectively using a gradient approach. We argue, that bicoherence is also a generally useful tool to analyze phase-amplitude coupling (PAC), by deriving formal relations between PAC and bispectra...
February 5, 2018: NeuroImage
Joanna Urban-Ciecko, Jean-Sebastien Jouhanneau, Stephanie E Myal, James F A Poulet, Alison L Barth
Sleep, waking, locomotion, and attention are associated with cell-type-specific changes in neocortical activity. The effect of brain state on circuit output requires understanding of how neuromodulators influence specific neuronal classes and their synapses, with normal patterns of neuromodulator release from endogenous sources. We investigated the state-dependent modulation of a ubiquitous feedforward inhibitory motif in mouse sensory cortex, local pyramidal (Pyr) inputs onto somatostatin (SST)-expressing interneurons...
February 7, 2018: Neuron
Driton Vela
Hepcidin is emerging as a new important factor in brain iron homeostasis. Studies suggest that there are two sources of hepcidin in the brain; one is local and the other comes from the circulation. Little is known about the molecular mediators of local hepcidin expression, but inflammation and iron-load have been shown to induce hepcidin expression in the brain. The most important source of hepcidin in the brain are glial cells. Role of hepcidin in brain functions has been observed during neuronal iron-load and brain hemorrhage, where secretion of abundant hepcidin is related with the severity of brain damage...
February 7, 2018: Journal of Translational Medicine
Fumihiko Igarashi, Mari H Ogihara, Masatoshi Iga, Hiroshi Kataoka
Dietary sterols including cholesterol and phytosterols are essential substrates for insect steroid hormone (ecdysteroid) synthesis in the prothoracic glands (PGs). In a silkworm Bombyx mori, one of the model species of insects, the steroidogenesis has been well demonstrated that cholesterol biotransformation into ecdysone in the PG cells. Because insects lack the ability to synthesize cellular sterol de novo, lipoprotein, lipophorin (Lp), has been thought to be the major cholesterol supply source; however, details of cholesterol behavior from Lp to the PG cells has not been analyzed till date...
January 31, 2018: Steroids
Asad Ali, Xiaoying Cui, Suzanne Alexander, Darryl Eyles
Emerging evidence suggests that maternal or developmental vitamin D (DVD) deficiency is a risk factor for Autism Spectrum Disorders. A well-established association has also been found between gestational infection and increased incidence of autism. Placenta mediates the maternal immune response in respect to the foetus. The placenta is also a major source of vitamin D and locally produced vitamin D is an essential regulator of immune function during pregnancy. Here we investigate the effects of DVD-deficiency on baseline placental immune status and in response to the well-known viral and bacterial immune activating agents polyriboinosinic-polyribocytidylic acid (poly(I:C) and lipopolysaccharide (LPS)...
February 3, 2018: Journal of Steroid Biochemistry and Molecular Biology
Shibao He, Yaru Yin, Xi Zheng, Dongdong Guo, Jia Xin, Yong Zhu
The head of the silkworm is a nerve center and a sense organ, contains antennaes and sensory hair, feels the outside signal, and responds to the external signal delivered to the brain. Juvenile hormone is mainly synthesized and secreted by corpora allata, and it needs to be played with the aid of the hormone binding protein, because the juvenile hormone binding protein is the carrier of juvenile hormone transport and plays a functional in vivo, they have an extremely important function in insects. The objective of this study is to screened and identify a novel BmTOL proteins that it has a conserved structure of the juvenile hormone binding protein family by SilkDB and NCBI database...
January 25, 2018: Sheng Wu Gong Cheng Xue Bao, Chinese Journal of Biotechnology
Lutz Kettler, Hannah Griebel, Roland Ferger, Hermann Wagner
A function of the auditory system is to accurately determine the location of a sound source. The main cues for sound location are interaural time (ITD) and level (ILD) differences. Humans use both ITD and ILD to determine the azimuth. Thus far, the conception of sound localization in barn owls was that their facial ruff and asymmetrical ears generate a two-dimensional grid of ITD for azimuth and ILD for elevation. We show that barn owls also use ILD for azimuthal sound localization when ITDs are ambiguous. For high-frequency narrowband sounds, midbrain neurons can signal multiple locations, leading to the perception of an auditory illusion called a phantom source...
November 2017: ENeuro
Sheng H Wang, Muriel Lobier, Felix Siebenhühner, Tuomas Puoliväli, Satu Palva, J Matias Palva
Inter-areal functional connectivity (FC), neuronal synchronization in particular, is thought to constitute a key systems-level mechanism for coordination of neuronal processing and communication between brain regions. Evidence to support this hypothesis has been gained largely using invasive electrophysiological approaches. In humans, neuronal activity can be non-invasively recorded only with magneto- and electroencephalography (MEG/EEG), which have been used to assess FC networks with high temporal resolution and whole-scalp coverage...
January 26, 2018: NeuroImage
Julia Siemann, Manfred Herrmann, Daniela Galashan
The present study examined whether feature-based cueing affects early or late stages of flanker conflict processing using EEG and fMRI. Feature cues either directed participants' attention to the upcoming colour of the target or were neutral. Validity-specific modulations during interference processing were investigated using the N200 event-related potential (ERP) component and BOLD signal differences. Additionally, both data sets were integrated using an fMRI-constrained source analysis. Finally, the results were compared with a previous study in which spatial instead of feature-based cueing was applied to an otherwise identical flanker task...
January 25, 2018: Scientific Reports
Annabel D Nijhof, Monica Dhar, Judith Goris, Marcel Brass, Jan R Wiersema
Diminished responding to hearing one's own name is one of the earliest and strongest predictors of autism spectrum disorder (ASD). Here, we studied, for the first time, the neural correlates of hearing one's own name in ASD. Based on existing research, we hypothesized enhancement of late parietal positive activity specifically for the own name in neurotypicals, and for this effect to be reduced in adults with ASD. Source localization analyses were conducted to estimate group differences in brain regions underlying this effect...
January 2018: Journal of Abnormal Psychology
Christian Brodbeck, Alessandro Presacco, Jonathan Z Simon
Human experience often involves continuous sensory information that unfolds over time. This is true in particular for speech comprehension, where continuous acoustic signals are processed over seconds or even minutes. We show that brain responses to such continuous stimuli can be investigated in detail, for magnetoencephalography (MEG) data by combining linear kernel estimation with minimum norm source localization. Previous research has shown that the requirement to average data over many trials can be overcome by modeling the brain response as a linear convolution of the stimulus and a kernel, or response function, and estimating a kernel that predicts the response from the stimulus...
January 20, 2018: NeuroImage
Julie Bolcaen, Benedicte Descamps, Tom Boterberg, Christian Vanhove, Ingeborg Goethals
For decades, small animal radiation research was mostly performed using fairly crude experimental setups applying simple single-beam techniques without the ability to target a specific or well-delineated tumor volume. The delivery of radiation was achieved using fixed radiation sources or linear accelerators producing megavoltage (MV) X-rays. These devices are unable to achieve sub-millimeter precision required for small animals. Furthermore, the high doses delivered to healthy surrounding tissue hamper response assessment...
December 28, 2017: Journal of Visualized Experiments: JoVE
Chiara Todaro, Laura Marzetti, Pedro A Valdés Sosa, Pedro A Valdés-Hernandez, Vittorio Pizzella
Electrocorticography (ECoG) is an electrophysiological technique that records brain activity directly from the cortical surface with high temporal (ms) and spatial (mm) resolution. Its major limitations are in the high invasiveness and in the restricted field-of-view of the electrode grid, which partially covers the cortex. To infer brain activity at locations different from just below the electrodes, it is necessary to solve the electromagnetic inverse problem. Limitations in the performance of source reconstruction algorithms from ECoG have been, to date, only partially addressed in the literature, and a systematic evaluation is still lacking...
January 23, 2018: Brain Topography
Zikuan Chen, Jennifer Robinson, Vince Calhoun
PURPOSE: To computationally separate dynamic brain functional BOLD responses from static background in a brain functional activity for forward fMRI signal analysis and inverse mapping. METHODS: A brain functional activity is represented in terms of magnetic source by a perturbation model: χ = χ0 +δχ, with δχ for BOLD magnetic perturbations and χ0 for background. A brain fMRI experiment produces a timeseries of complex-valued images (T2* images), whereby we extract the BOLD phase signals (denoted by δP) by a complex division...
2018: PloS One
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