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https://www.readbyqxmd.com/read/27909395/reversal-learning-in-humans-and-gerbils-dynamic-control-network-facilitates-learning
#1
Christian Jarvers, Tobias Brosch, André Brechmann, Marie L Woldeit, Andreas L Schulz, Frank W Ohl, Marcel Lommerzheim, Heiko Neumann
Biologically plausible modeling of behavioral reinforcement learning tasks has seen great improvements over the past decades. Less work has been dedicated to tasks involving contingency reversals, i.e., tasks in which the original behavioral goal is reversed one or multiple times. The ability to adjust to such reversals is a key element of behavioral flexibility. Here, we investigate the neural mechanisms underlying contingency-reversal tasks. We first conduct experiments with humans and gerbils to demonstrate memory effects, including multiple reversals in which subjects (humans and animals) show a faster learning rate when a previously learned contingency re-appears...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27899890/causal-role-of-thalamic-interneurons-in-brain-state-transitions-a-study-using-a-neural-mass-model-implementing-synaptic-kinetics
#2
Basabdatta Sen Bhattacharya, Thomas P Bond, Louise O'Hare, Daniel Turner, Simon J Durrant
Experimental studies on the Lateral Geniculate Nucleus (LGN) of mammals and rodents show that the inhibitory interneurons (IN) receive around 47.1% of their afferents from the retinal spiking neurons, and constitute around 20-25% of the LGN cell population. However, there is a definite gap in knowledge about the role and impact of IN on thalamocortical dynamics in both experimental and model-based research. We use a neural mass computational model of the LGN with three neural populations viz. IN, thalamocortical relay (TCR), thalamic reticular nucleus (TRN), to study the causality of IN on LGN oscillations and state-transitions...
2016: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/27899887/saccadic-adaptation-alters-the-attentional-field
#3
Farahnaz A Wick, Tyler W Garaas, Marc Pomplun
It is currently unknown whether changes to the oculomotor system can induce changes to the distribution of spatial attention around a fixated target. Previous studies have used perceptual performance tasks to show that adaptation of saccadic eye movements affects dynamic properties of visual attention, in particular, attentional shifts to a cued location. In this study, we examined the effects of saccadic adaptation on the static distribution of visual attention around fixation (attentional field). We used the classic double step adaptation procedure and a flanker task to test for differences in the attentional field after forward and backward adaptation...
2016: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/27897668/global-enhancement-but-local-suppression-in-feature-based-attention
#4
Norman Forschack, Søren K Andersen, Matthias M Müller
A key property of feature-based attention is global facilitation of the attended feature throughout the visual field. Previously, we presented superimposed red and blue randomly moving dot kinematograms (RDKs) flickering at a different frequency each to elicit frequency-specific steady-state visual evoked potentials (SSVEPs) that allowed us to analyze neural dynamics in early visual cortex when participants shifted attention to one of the two colors. Results showed amplification of the attended and suppression of the unattended color as measured by SSVEP amplitudes...
November 29, 2016: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/27889814/an-fmri-study-of-training-voluntary-smooth-circular-eye-movements
#5
Raimund Kleiser, Cornelia Stadler, Sibylle Wimmer, Thomas Matyas, Rüdiger J Seitz
Despite a large number of recent studies, the promise of fMRI methods to produce valuable insights into motor skill learning has been restricted to sequence learning paradigms, or manual training paradigms where a relatively advanced capacity for sensory-motor integration and effector coordination already exists. We therefore obtained fMRIs from 16 healthy adults trained in a new paradigm that demanded voluntary smooth circular eye movements without a moving target. This aimed to monitor neural activation during two possible motor learning processes: (a) the smooth pursuit control system develops a new perceptual-motor relationship and successfully becomes involved in voluntary action in which it is not normally involved or (b) the saccadic system normally used for voluntary eye movement and which only exhibits linear action skill develops new dynamic coordinative control capable of smooth circular movement...
November 26, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27877113/the-effects-of-realistic-synaptic-distribution-and-3d-geometry-on-signal-integration-and-extracellular-field-generation-of-hippocampal-pyramidal-cells-and-inhibitory-neurons
#6
Attila I Gulyás, Tamás F Freund, Szabolcs Káli
In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells (PCs) and interneurons in the hippocampal CA1 area...
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27872267/endophenotypes-epigenetics-polygenicity-and-more-irv-gottesman-s-dynamic-legacy
#7
David L Braff, Carol A Tamminga
First, we describe the hallmark contributions of Irv Gottesman's pioneering scholarship for schizophrenia research including concepts of polygenicity, gene × environment interactions, epigenetics and the endophenotype concept. Gottesman and colleagues' twin studies showed that genes, not social factors, mediate schizophrenia risk. He then showed that schizophrenia is highly polygenic. Next, he introduced the concept of epigenetics into schizophrenia research. Gottesman then introduced the quantitative endophenotype concept...
November 21, 2016: Schizophrenia Bulletin
https://www.readbyqxmd.com/read/27870609/time-series-decomposition-into-oscillation-components-and-phase-estimation
#8
Takeru Matsuda, Fumiyasu Komaki
Many time series are naturally considered as a superposition of several oscillation components. For example, electroencephalogram (EEG) time series include oscillation components such as alpha, beta, and gamma. We propose a method for decomposing time series into such oscillation components using state-space models. Based on the concept of random frequency modulation, gaussian linear state-space models for oscillation components are developed. In this model, the frequency of an oscillator fluctuates by noise...
November 21, 2016: Neural Computation
https://www.readbyqxmd.com/read/27853431/developing-dynamic-field-theory-architectures-for-embodied-cognitive-systems-with-cedar
#9
Oliver Lomp, Mathis Richter, Stephan K U Zibner, Gregor Schöner
Embodied artificial cognitive systems, such as autonomous robots or intelligent observers, connect cognitive processes to sensory and effector systems in real time. Prime candidates for such embodied intelligence are neurally inspired architectures. While components such as forward neural networks are well established, designing pervasively autonomous neural architectures remains a challenge. This includes the problem of tuning the parameters of such architectures so that they deliver specified functionality under variable environmental conditions and retain these functions as the architectures are expanded...
2016: Frontiers in Neurorobotics
https://www.readbyqxmd.com/read/27852771/reduced-efficacy-of-the-kcc2-cotransporter-promotes-epileptic-oscillations-in-a-subiculum-network-model
#10
Anatoly Buchin, Anton Chizhov, Gilles Huberfeld, Richard Miles, Boris S Gutkin
: Pharmacoresistant epilepsy is a chronic neurological condition in which a basal brain hyperexcitability results in paroxysmal hypersynchronous neuronal discharges. Human temporal lobe epilepsy has been associated with dysfunction or loss of the potassium-chloride cotransporter KCC2 in a subset of pyramidal cells in the subiculum, a key structure generating epileptic activities. KCC2 regulates intraneuronal chloride and extracellular potassium levels by extruding both ions. Absence of effective KCC2 may alter the dynamics of chloride and potassium levels during repeated activation of GABAergic synapses due to interneuron activity...
November 16, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27830650/relationships-between-cortical-myeloarchitecture-and-electrophysiological-networks
#11
Benjamin A E Hunt, Prejaas K Tewarie, Olivier E Mougin, Nicolas Geades, Derek K Jones, Krish D Singh, Peter G Morris, Penny A Gowland, Matthew J Brookes
The human brain relies upon the dynamic formation and dissolution of a hierarchy of functional networks to support ongoing cognition. However, how functional connectivities underlying such networks are supported by cortical microstructure remains poorly understood. Recent animal work has demonstrated that electrical activity promotes myelination. Inspired by this, we test a hypothesis that gray-matter myelin is related to electrophysiological connectivity. Using ultra-high field MRI and the principle of structural covariance, we derive a structural network showing how myelin density differs across cortical regions and how separate regions can exhibit similar myeloarchitecture...
November 8, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27822495/scale-free-neural-and-physiological-dynamics-in-naturalistic-stimuli-processing
#12
Amy Lin, Brian Maniscalco, Biyu J He
Neural activity recorded at multiple spatiotemporal scales is dominated by arrhythmic fluctuations without a characteristic temporal periodicity. Such activity often exhibits a 1/f-type power spectrum, in which power falls off with increasing frequency following a power-law function: [Formula: see text], which is indicative of scale-free dynamics. Two extensively studied forms of scale-free neural dynamics in the human brain are slow cortical potentials (SCPs)-the low-frequency (<5 Hz) component of brain field potentials-and the amplitude fluctuations of α oscillations, both of which have been shown to carry important functional roles...
September 2016: ENeuro
https://www.readbyqxmd.com/read/27814463/mittag-leffler-stability-of-fractional-order-neural-networks-in-the-presence-of-generalized-piecewise-constant-arguments
#13
Ailong Wu, Ling Liu, Tingwen Huang, Zhigang Zeng
Neurodynamic system is an emerging research field. To understand the essential motivational representations of neural activity, neurodynamics is an important question in cognitive system research. This paper is to investigate Mittag-Leffler stability of a class of fractional-order neural networks in the presence of generalized piecewise constant arguments. To identify neural types of computational principles in mathematical and computational analysis, the existence and uniqueness of the solution of neurodynamic system is the first prerequisite...
October 14, 2016: Neural Networks: the Official Journal of the International Neural Network Society
https://www.readbyqxmd.com/read/27785464/phase-dependent-modulation-of-oscillatory-phase-and-synchrony-by-long-lasting-depolarizing-inputs-in-central-neurons
#14
Satoshi Watanabe, Moritoshi Hirono
Oscillatory neural activities have been implicated in various types of information processing in the CNS. The procerebral (PC) lobe of the land mollusk Limax valentianus shows an ongoing oscillatory local field potential (LFP). Olfactory input increases both the frequency and spatial synchrony of the LFP oscillation by a nitric oxide (NO)-mediated mechanism, but how NO modulates the activity in a specific manner has been unclear. In the present study, we used electrical stimulation and NO uncaging to systematically analyze the response of the LFP oscillation and found phase-dependent effects on phase shifting and synchrony...
September 2016: ENeuro
https://www.readbyqxmd.com/read/27756615/cytoskeletal-dynamics-during-in-vitro-neurogenesis-of-induced-pluripotent-stem-cells-ipscs
#15
Claudia Compagnucci, Emanuela Piermarini, Antonella Sferra, Rossella Borghi, Alessia Niceforo, Stefania Petrini, Fiorella Piemonte, Enrico Bertini
Patient-derived induced pluripotent stem cells (iPSCs) provide a novel tool to investigate the pathophysiology of poorly known diseases, in particular those affecting the nervous system, which has been difficult to study for its lack of accessibility. In this emerging and promising field, recent iPSCs studies are mostly used as "proof-of-principle" experiments that are confirmatory of previous findings obtained from animal models and postmortem human studies; its promise as a discovery tool is just beginning to be realized...
December 2016: Molecular and Cellular Neurosciences
https://www.readbyqxmd.com/read/27746231/tracking-recurrence-of-correlation-structure-in-neuronal-recordings
#16
Samuel A Neymotin, Zoe N Talbot, Jeeyune Q Jung, André A Fenton, William W Lytton
BACKGROUND: Correlated neuronal activity in the brain is hypothesized to contribute to information representation, and is important for gauging brain dynamics in health and disease. Due to high dimensional neural datasets, it is difficult to study temporal variations in correlation structure. NEW METHOD: We developed a multiscale method, Population Coordination (PCo), to assess neural population structure in multiunit single neuron ensemble and multi-site local field potential (LFP) recordings...
October 13, 2016: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/27736873/identifying-anatomical-origins-of-coexisting-oscillations-in-the-cortical-microcircuit
#17
Hannah Bos, Markus Diesmann, Moritz Helias
Oscillations are omnipresent in neural population signals, like multi-unit recordings, EEG/MEG, and the local field potential. They have been linked to the population firing rate of neurons, with individual neurons firing in a close-to-irregular fashion at low rates. Using a combination of mean-field and linear response theory we predict the spectra generated in a layered microcircuit model of V1, composed of leaky integrate-and-fire neurons and based on connectivity compiled from anatomical and electrophysiological studies...
October 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27729529/fast-fmri-can-detect-oscillatory-neural-activity-in-humans
#18
Laura D Lewis, Kawin Setsompop, Bruce R Rosen, Jonathan R Polimeni
Oscillatory neural dynamics play an important role in the coordination of large-scale brain networks. High-level cognitive processes depend on dynamics evolving over hundreds of milliseconds, so measuring neural activity in this frequency range is important for cognitive neuroscience. However, current noninvasive neuroimaging methods are not able to precisely localize oscillatory neural activity above 0.2 Hz. Electroencephalography and magnetoencephalography have limited spatial resolution, whereas fMRI has limited temporal resolution because it measures vascular responses rather than directly recording neural activity...
October 25, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27726845/sensory-dynamics-of-visual-hallucinations-in-the-normal-population
#19
Joel Pearson, Rocco Chiou, Sebastian Rogers, Marcus Wicken, Stewart Heitmann, Bard Ermentrout
Hallucinations occur in both normal and clinical populations. Due to their unpredictability and complexity, the mechanisms underlying hallucinations remain largely untested. Here we show that visual hallucinations can be induced in the normal population by visual flicker, limited to an annulus that constricts content complexity to simple moving grey blobs, allowing objective mechanistic investigation. Hallucination strength peaked at ~11 Hz flicker and was dependent on cortical processing. Hallucinated motion speed increased with flicker rate, when mapped onto visual cortex it was independent of eccentricity, underwent local sensory adaptation and showed the same bistable and mnemonic dynamics as sensory perception...
October 11, 2016: ELife
https://www.readbyqxmd.com/read/27722603/neural-network-molecular-dynamics-simulations-of-solid-liquid-interfaces-water-at-low-index-copper-surfaces
#20
Suresh Kondati Natarajan, Jörg Behler
Solid-liquid interfaces have received considerable attention in recent years due to their central role in many technologically relevant fields like electrochemistry, heterogeneous catalysis and corrosion. As the chemical processes in these examples take place primarily at the interface, understanding the structural and dynamical properties of the interfacial water molecules is of vital importance. Here, we use a first-principles quality high-dimensional neural network potential built from dispersion-corrected density functional theory data in molecular dynamics simulations to investigate water-copper interfaces as a prototypical case...
October 7, 2016: Physical Chemistry Chemical Physics: PCCP
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