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dynamic neural field

Hulusi Kafaligonul, Thomas D Albright, Gene R Stoner
The timing of brief stationary sounds has been shown to alter the perceived speed of visual apparent motion (AM), presumably by altering the perceived timing of the individual frames of the AM stimuli and/or the duration of the inter-stimulus intervals (ISIs) between those frames. To investigate the neural correlates of this "temporal ventriloquism" illusion, we recorded spiking and local field potential (LFP) activity from area MT (the middle temporal area) in awake, fixating macaques. We found that the spiking activity of most MT neurons (but not the LFP) was tuned for the ISI/speed (these parameters co-varied) of our AM stimuli but that auditory timing had no effect on that tuning...
June 20, 2018: Journal of Neurophysiology
Antje Kilias, Andres Canales, Ulrich P Froriep, Seongjun Park, Ulrich Egert, Polina Anikeeva
Optogenetic modulation of neural activity is a ubiquitous tool for basic investigation of brain circuits. While the majority of optogenetic paradigms rely on short light pulses to evoke synchronized activity of optically sensitized cells, many neurobiological processes are associated with slow local field potential (LFP) oscillations. Therefore, we developed a hybrid fiber probe capable of simultaneous electrophysiological recording and optical stimulation and used it to investigate the utility of sinusoidal light stimulation for evoking oscillatory neural activity in vivo across a broad frequency range...
June 20, 2018: Journal of Neural Engineering
Axel Hutt, Jérémie Lefebvre, Darren Hight, Jamie Sleigh
The physiological mechanisms by which anaesthetic drugs modulate oscillatory brain activity remain poorly understood. Combining human data, mathematical and computational analysis of both spiking and mean-field models, we investigated the spectral dynamics of encephalographic (EEG) beta-alpha oscillations, observed in human patients undergoing general anaesthesia. The effect of anaesthetics can be modelled as a reduction of neural fluctuation intensity, and/or an increase in inhibitory synaptic gain in the thalamo-cortical circuit...
June 16, 2018: NeuroImage
Gavin Jenkins, Paul Tupper
Transposition is a tendency for organisms to generalize relationships between stimuli in situations where training does not objectively reward relationships over absolute, static associations. Transposition has most commonly been explained as either conceptual understanding of relationships (Köhler, 1938) as nonconceptual effects of neural memory gradients (as in Spence's stimulus discrimination theory, 1937). Most behavioral evidence can be explained by the gradient account, but a key finding unexplained by gradients is intermediate transposition, where a central (of three) stimulus, "relationally correct response," is generalized from training to test...
June 12, 2018: Neural Computation
Farouk Zouari, Asier Ibeas, Abdesselem Boulkroune, Jinde Cao, Mohammad Mehdi Arefi
This study addresses the issue of the adaptive output tracking control for a category of uncertain nonstrict-feedback delayed incommensurate fractional-order systems in the presence of nonaffine structures, unmeasured pseudo-states, unknown control directions, unknown actuator nonlinearities and output constraints. Firstly, the mean value theorem and the Gaussian error function are introduced to eliminate the difficulties that arise from the nonaffine structures and the unknown actuator nonlinearities, respectively...
June 1, 2018: Neural Networks: the Official Journal of the International Neural Network Society
Serge O Dumoulin, Tomas Knapen
Receptive fields are a core property of cortical organization. Modern neuroimaging allows routine access to visual population receptive fields (pRFs), enabling investigations of clinical disorders. Yet how the underlying neural circuitry operates is controversial. The controversy surrounds observations that measurements of pRFs can change in healthy adults as well as in patients with a range of ophthalmological and neurological disorders. The debate relates to the balance between plasticity and stability of the underlying neural circuitry...
June 11, 2018: Annual Review of Vision Science
Anna Shin, Jeonghoon Woo, Jung Eun Kim, Daesoo Kim
Drowsiness is an awake state with increased sleep drive, yet the neural correlates and underlying mechanisms remains unclear. Here, we established a mouse model of drowsiness, where mice are fasted for 1 day and then allowed to overeat high-fat food (to promote sleep) while positioned in an open-field box (to promote vigilance). They fall into a long-lasting drowsy state, as reflected by repeated and open-eyed nodding of the head while in a standing position. Simultaneous recording of electroencephalogram (EEG) and neck electromyogram (EMG) readouts revealed that this drowsy state including nodding state had multiple stages in terms of the relationship between the level of vigilance and head movement: delta oscillations decreased in power prior to the head-nodding period and increased during the non-nodding period...
June 7, 2018: Molecular Brain
Matthew C Costello, Aaron T Buss
Visual working memory (VWM) is essential for executive function and is known to be compromised in older adults. Yet, the cognitive and neural processes associated with these age-related changes remain inconclusive. The purpose of this study is to explore such factors with a dynamic neural field (DNF) model that was manipulated to replicate the behavioral performances of younger and older adults in a change detection task. Although previous work has successfully modeled children and younger adult VWM performance, this study represents the first attempt to model older adult VWM performance within the DNF architecture...
June 7, 2018: Journal of Cognitive Neuroscience
Torbjørn V Ness, Michiel W H Remme, Gaute T Einevoll
In cortex the local field potential (LFP) is thought to mainly stem from correlated synaptic input to populations of geometrically aligned neurons. Computer models of single cortical pyramidal neurons showed that subthreshold voltage-dependent membrane conductances can also shape the LFP signal, in particular the h-type current, Ih This ion-channel is prominent in various types of pyramidal neurons, typically showing an increasing density gradient along the apical dendrites. Here, we investigate how Ih affects the LFP generated by a model of a population of cortical pyramidal neurons...
June 6, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Eva-Maria Reuter, Gregory E P Pearcey, Timothy J Carroll
Although age-related declines in cognitive, sensory and motor capacities are well documented, current evidence is mixed as to whether or not aging impairs sensorimotor adaptation to a novel dynamic environment. More importantly, the extent to which any deficits in sensorimotor adaptation are due to general impairments in neural plasticity, or impairments in the specific processes that drive adaptation is unclear. Here we investigated whether there are age-related differences in electrophysiological responses to reaching endpoint and trajectory errors caused by a novel force field, and whether markers of error processing relate to the ability of older adults to adapt their movements...
June 2, 2018: Experimental Gerontology
Sean P Parsons, Jan D Huizinga
NEW FINDINGS: What is the central question of this study? What is the nature of slow wave driven contraction frequency gradients in the small intestine? What is the main finding and its importance? Frequency plateaus are composed of discrete waves of increased interval, each wave associated with a contraction dislocation. Smooth frequency gradients are generated by localised neural modulation of wave frequency, leading to functionally important wave turbulence. Both patterns are emergent properties of a network of coupled oscillators, the interstitial cells of Cajal...
June 3, 2018: Experimental Physiology
Jiao Yang Lu, Qiu Yan Zhu, Xin Xing Zhang, Fu Rui Zhang, Wei Tao Huang, Xue Zhi Ding, Li Qiu Xia, Hong Qun Luo, Nian Bing Li
Due to rapid change in information technology, many consumer electronics become electronic waste which is the fastest-growing pollution problems worldwide. In fact, many discarded electronics with prefabricated micro/nanostructures may provide a good basis to fulfill special needs of other fields, such as tissue engineering, biosensors, and energy. Herein, to take waste optical discs as an example, we demonstrate that discarded electronics can be directly repurposed as highly anisotropic platforms for in vitro investigation of cell behaviors, such as cell adhesion, cell alignment, and cell-cell interactions...
May 28, 2018: Ecotoxicology and Environmental Safety
Payam Emami Khoonsari, Elena Ossipova, Johan Lengqvist, Camilla I Svensson, Eva Kosek, Diana Kadetoff, Per-Johan Jakobsson, Kim Kultima, Jon Lampa
Chronic pain represents one of the major medical challenges in the 21st century, affecting >1.5 billion of the world population. Overlapping and heterogenous symptoms of various chronic pain conditions complicate their diagnosis, emphasizing the need for more specific biomarkers to improve the diagnosis and understand the disease mechanisms. We have here investigated proteins found in human CSF with respect to known "pain" genes and in a cohort of patients with dysfunctional pain (fibromyalgia, FM), inflammatory pain (rheumatoid arthritis patients, RA) and non-pain controls utilized semi-quantitative proteomics using mass spectrometry (MS) to explore quantitative differences between these cohorts of patients...
May 28, 2018: Journal of Proteomics
Eli J Müller, Peter A Robinson
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is modeled to explore the mechanisms of this effective, but poorly understood, treatment for motor symptoms of drug-refractory Parkinson's disease and dystonia. First, a neural field model of the corticothalamic-basal ganglia (CTBG) system is developed that reproduces key clinical features of Parkinson's disease, including its characteristic 4-8 Hz and 13-30 Hz electrophysiological signatures. Deep brain stimulation of the STN is then modeled and shown to suppress the pathological 13-30 Hz (beta) activity for physiologically realistic and optimized stimulus parameters...
May 29, 2018: PLoS Computational Biology
Viola Priesemann, Oren Shriki
The finding of power law scaling in neural recordings lends support to the hypothesis of critical brain dynamics. However, power laws are not unique to critical systems and can arise from alternative mechanisms. Here, we investigate whether a common time-varying external drive to a set of Poisson units can give rise to neuronal avalanches and exhibit apparent criticality. To this end, we analytically derive the avalanche size and duration distributions, as well as additional measures, first for homogeneous Poisson activity, and then for slowly varying inhomogeneous Poisson activity...
May 29, 2018: PLoS Computational Biology
Julie Fourneau, Marie-Hélène Canu, Caroline Cieniewski-Bernard, Bruno Bastide, Erwan Dupont
In human, a chronic sensorimotor perturbation (SMP) through prolonged body immobilization alters motor task performance through a combination of peripheral and central factors. Studies performed on a rat model of SMP have shown biomolecular changes and a reorganization of sensorimotor cortex through events such as morphological modifications of dendritic spines (number, length, functionality). However, underlying mechanisms are still unclear. It is well known that phosphorylation regulates a wide field of synaptic activity leading to neuroplasticity...
May 28, 2018: Journal of Neurochemistry
F Deeba, Paula Sanz-Leon, P A Robinson
A neural field model of the corticothalamic system is applied to investigate the temporal and spectral characteristics of absence seizures in the presence of a temporally varying connection strength between the cerebral cortex and thalamus. Increasing connection strength drives the system into an absence seizure-like state once a threshold is passed and a supercritical Hopf bifurcation occurs. The dynamics and spectral characteristics of the resulting model seizures are explored as functions of maximum connection strength, time above threshold, and the rate at which the connection strength increases (ramp rate)...
May 25, 2018: Journal of Theoretical Biology
Han Shao, Tingting Li, Rong Zhu, Xiaoting Xu, Jiandong Yu, Shengfeng Chen, Li Song, Seeram Ramakrishna, Zhigang Lei, Yiwen Ruan, Liumin He
Carbon nanotubes (CNTs) have shown potential applications in neuroscience as growth substrates owing to their numerous unique properties. However, a key concern in the fabrication of homogeneous composites is the serious aggregation of CNTs during incorporation into the biomaterial matrix. Moreover, the regulation mechanism of CNT-based substrates on neural differentiation remains unclear. Here, a novel strategy was introduced for the construction of CNT nanocomposites via layer-by-layer assembly of negatively charged multi-walled CNTs and positively charged poly(dimethyldiallylammonium chloride)...
August 2018: Biomaterials
Hao Wang, Weitao Yang
We developed a novel neural network based force field for water based on training with high level ab initio theory. The force field was built based on electrostatically embedded many-body expansion method truncated at binary interactions. Many-body expansion method is a common strategy to partition the total Hamiltonian of large systems into a hierarchy of few-body terms. Neural networks were trained to represent electrostatically embedded one-body and two-body interactions, which require as input only one and two water molecule calculations at the level of ab initio electronic structure method CCSD/aug-cc-pVDZ embedded in the molecular mechanics water environment, making it efficient as a general force field construction approach...
May 18, 2018: Journal of Physical Chemistry Letters
Ann Clock Eddins, Erol J Ozmeral, David A Eddins
Over the years, the effect of aging on auditory function has been investigated in animal models and humans in an effort to characterize age-related changes in both perception and physiology. Here, we review how aging may impact neural encoding and processing of binaural and spatial cues in human listeners with a focus on recent work by the authors as well as others. Age-related declines in monaural temporal processing, as estimated from measures of gap detection and temporal fine structure discrimination, have been associated with poorer performance on binaural tasks that require precise temporal processing...
May 5, 2018: Hearing Research
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