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Frontiers in Computational Neuroscience

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https://www.readbyqxmd.com/read/28539881/the-influence-of-mexican-hat-recurrent-connectivity-on-noise-correlations-and-stimulus-encoding
#1
Robert Meyer, Josef Ladenbauer, Klaus Obermayer
Noise correlations are a common feature of neural responses and have been observed in many cortical areas across different species. These correlations can influence information processing by enhancing or diminishing the quality of the neural code, but the origin of these correlations is still a matter of controversy. In this computational study we explore the hypothesis that noise correlations are the result of local recurrent excitatory and inhibitory connections. We simulated two-dimensional networks of adaptive spiking neurons with local connection patterns following Gaussian kernels...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28522969/equilibrium-propagation-bridging-the-gap-between-energy-based-models-and-backpropagation
#2
Benjamin Scellier, Yoshua Bengio
We introduce Equilibrium Propagation, a learning framework for energy-based models. It involves only one kind of neural computation, performed in both the first phase (when the prediction is made) and the second phase of training (after the target or prediction error is revealed). Although this algorithm computes the gradient of an objective function just like Backpropagation, it does not need a special computation or circuit for the second phase, where errors are implicitly propagated. Equilibrium Propagation shares similarities with Contrastive Hebbian Learning and Contrastive Divergence while solving the theoretical issues of both algorithms: our algorithm computes the gradient of a well-defined objective function...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28507514/markovian-analysis-of-the-sequential-behavior-of-the-spontaneous-spinal-cord-dorsum-potentials-induced-by-acute-nociceptive-stimulation-in-the-anesthetized-cat
#3
Mario Martin, Javier Béjar, Gennaro Esposito, Diógenes Chávez, Enrique Contreras-Hernández, Silvio Glusman, Ulises Cortés, Pablo Rudomín
In a previous study we developed a Machine Learning procedure for the automatic identification and classification of spontaneous cord dorsum potentials (CDPs). This study further supported the proposal that in the anesthetized cat, the spontaneous CDPs recorded from different lumbar spinal segments are generated by a distributed network of dorsal horn neurons with structured (non-random) patterns of functional connectivity and that these configurations can be changed to other non-random and stable configurations after the noceptive stimulation produced by the intradermic injection of capsaicin in the anesthetized cat...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28491031/control-of-absence-seizures-by-the-thalamic-feed-forward-inhibition
#4
Mingming Chen, Daqing Guo, Yang Xia, Dezhong Yao
As a subtype of idiopathic generalized epilepsies, absence epilepsy is believed to be caused by pathological interactions within the corticothalamic (CT) system. Using a biophysical mean-field model of the CT system, we demonstrate here that the feed-forward inhibition (FFI) in thalamus, i.e., the pathway from the cerebral cortex (Ctx) to the thalamic reticular nucleus (TRN) and then to the specific relay nuclei (SRN) of thalamus that are also directly driven by the Ctx, may participate in controlling absence seizures...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28487645/forearm-flexor-muscles-in-children-with-cerebral-palsy-are-weak-thin-and-stiff
#5
Ferdinand von Walden, Kian Jalaleddini, Björn Evertsson, Johanna Friberg, Francisco J Valero-Cuevas, Eva Pontén
Children with cerebral palsy (CP) often develop reduced passive range of motion with age. The determining factor underlying this process is believed to be progressive development of contracture in skeletal muscle that likely changes the biomechanics of the joints. Consequently, to identify the underlying mechanisms, we modeled the mechanical characteristics of the forearm flexors acting across the wrist joint. We investigated skeletal muscle strength (Grippit®) and passive stiffness and viscosity of the forearm flexors in 15 typically developing (TD) children (10 boys/5 girls, mean age 12 years, range 8-18 yrs) and nine children with CP Nine children (6 boys/3 girls, mean age 11 ± 3 years (yrs), range 7-15 yrs) using the NeuroFlexor® apparatus...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28487644/a-computational-analysis-of-the-function-of-three-inhibitory-cell-types-in-contextual-visual-processing
#6
Jung H Lee, Christof Koch, Stefan Mihalas
Most cortical inhibitory cell types exclusively express one of three genes, parvalbumin, somatostatin and 5HT3a. We conjecture that these three inhibitory neuron types possess distinct roles in visual contextual processing based on two observations. First, they have distinctive synaptic sources and targets over different spatial extents and from different areas. Second, the visual responses of cortical neurons are affected not only by local cues, but also by visual context. We use modeling to relate structural information to function in primary visual cortex (V1) of the mouse, and investigate their role in contextual visual processing...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28484385/an-evaluation-of-the-accuracy-of-classical-models-for-computing-the-membrane-potential-and-extracellular-potential-for-neurons
#7
Aslak Tveito, Karoline H Jæger, Glenn T Lines, Łukasz Paszkowski, Joakim Sundnes, Andrew G Edwards, Tuomo Māki-Marttunen, Geir Halnes, Gaute T Einevoll
Two mathematical models are part of the foundation of Computational neurophysiology; (a) the Cable equation is used to compute the membrane potential of neurons, and, (b) volume-conductor theory describes the extracellular potential around neurons. In the standard procedure for computing extracellular potentials, the transmembrane currents are computed by means of (a) and the extracellular potentials are computed using an explicit sum over analytical point-current source solutions as prescribed by volume conductor theory...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28484384/mechanisms-of-winner-take-all-and-group-selection-in-neuronal-spiking-networks
#8
Yanqing Chen
A major function of central nervous systems is to discriminate different categories or types of sensory input. Neuronal networks accomplish such tasks by learning different sensory maps at several stages of neural hierarchy, such that different neurons fire selectively to reflect different internal or external patterns and states. The exact mechanisms of such map formation processes in the brain are not completely understood. Here we study the mechanism by which a simple recurrent/reentrant neuronal network accomplish group selection and discrimination to different inputs in order to generate sensory maps...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28473765/feature-detection-in-visual-cortex-during-different-functional-states
#9
Pavel Esir, Alexander Simonov, Misha Tsodyks
Cortical activity exhibits distinct characteristics in different functional states. In awake behaving animals it shows less synchrony, while in rest or sleeping state cortical activity is most synchronous. Previous studies showed that switching between functional states can change the efficiency of flowing sensory information. Switching between functional states can be triggered by releasing neuromodulators which affect neurotransmitter release probability and depolarization of cortical neurons. In this work we focus on studying primary visual area V1, by using firing rate ring model with short-term synaptic depression (STD)...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28469569/eliminating-absence-seizures-through-the-deep-brain-stimulation-to-thalamus-reticular-nucleus
#10
Zhihui Wang, Qingyun Wang
Deep brain stimulation (DBS) can play a crucial role in the modulation of absence seizures, yet relevant biophysical mechanisms are not completely established. In this paper, on the basis of a biophysical mean-field model, we investigate a typical absence epilepsy activity by introducing slow kinetics of GABAB receptors on thalamus reticular nucleus (TRN). We find that the region of spike and slow-wave discharges (SWDs) can be reduced greatly when we add the DBS to TRN. Furthermore, we systematically explore how the corresponding stimulation parameters including frequency, amplitude and positive input duration suppress the SWDs under certain conditions...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28458635/analysis-and-modeling-of-subthreshold-neural-multi-electrode-array-data-by-statistical-field-theory
#11
Måns Henningson, Sebastian Illes
Multi-electrode arrays (MEA) are increasingly used to investigate spontaneous neuronal network activity. The recorded signals comprise several distinct components: Apart from artifacts without biological significance, one can distinguish between spikes (action potentials) and subthreshold fluctuations (local fields potentials). Here we aim to develop a theoretical model that allows for a compact and robust characterization of subthreshold fluctuations in terms of a Gaussian statistical field theory in two spatial and one temporal dimension...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28458634/understanding-epileptiform-after-discharges-as-rhythmic-oscillatory-transients
#12
Gerold Baier, Peter N Taylor, Yujiang Wang
Electro-cortical activity in patients with epilepsy may show abnormal rhythmic transients in response to stimulation. Even when using the same stimulation parameters in the same patient, wide variability in the duration of transient response has been reported. These transients have long been considered important for the mapping of the excitability levels in the epileptic brain but their dynamic mechanism is still not well understood. To investigate the occurrence of abnormal transients dynamically, we use a thalamo-cortical neural population model of epileptic spike-wave activity and study the interaction between slow and fast subsystems...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28450833/optimal-control-based-stiffness-identification-of-an-ankle-foot-orthosis-using-a-predictive-walking-model
#13
Manish Sreenivasa, Matthew Millard, Martin Felis, Katja Mombaur, Sebastian I Wolf
Predicting the movements, ground reaction forces and neuromuscular activity during gait can be a valuable asset to the clinical rehabilitation community, both to understand pathology, as well as to plan effective intervention. In this work we use an optimal control method to generate predictive simulations of pathological gait in the sagittal plane. We construct a patient-specific model corresponding to a 7-year old child with gait abnormalities and identify the optimal spring characteristics of an ankle-foot orthosis that minimizes muscle effort...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28424606/bifurcation-analysis-on-phase-amplitude-cross-frequency-coupling-in-neural-networks-with-dynamic-synapses
#14
Takumi Sase, Yuichi Katori, Motomasa Komuro, Kazuyuki Aihara
We investigate a discrete-time network model composed of excitatory and inhibitory neurons and dynamic synapses with the aim at revealing dynamical properties behind oscillatory phenomena possibly related to brain functions. We use a stochastic neural network model to derive the corresponding macroscopic mean field dynamics, and subsequently analyze the dynamical properties of the network. In addition to slow and fast oscillations arising from excitatory and inhibitory networks, respectively, we show that the interaction between these two networks generates phase-amplitude cross-frequency coupling (CFC), in which multiple different frequency components coexist and the amplitude of the fast oscillation is modulated by the phase of the slow oscillation...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28420975/beta-band-corticomuscular-drive-reflects-muscle-coordination-strategies
#15
Alexander Reyes, Christopher M Laine, Jason J Kutch, Francisco J Valero-Cuevas
During force production, hand muscle activity is known to be coherent with activity in primary motor cortex, specifically in the beta-band (15-30 Hz) frequency range. It is not clear, however, if this coherence reflects the control strategy selected by the nervous system for a given task, or if it instead reflects an intrinsic property of cortico-spinal communication. Here, we measured corticomuscular and intermuscular coherence between muscles of index finger and thumb while a two-finger pinch grip of identical net force was applied to objects which were either stable (allowing synergistic activation of finger muscles) or unstable (requiring individuated finger control)...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28408878/reward-based-motor-adaptation-mediated-by-basal-ganglia
#16
Taegyo Kim, Khaldoun C Hamade, Dmitry Todorov, William H Barnett, Robert A Capps, Elizaveta M Latash, Sergey N Markin, Ilya A Rybak, Yaroslav I Molkov
It is widely accepted that the basal ganglia (BG) play a key role in action selection and reinforcement learning. However, despite considerable number of studies, the BG architecture and function are not completely understood. Action selection and reinforcement learning are facilitated by the activity of dopaminergic neurons, which encode reward prediction errors when reward outcomes are higher or lower than expected. The BG are thought to select proper motor responses by gating appropriate actions, and suppressing inappropriate ones...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28381996/evaluation-of-a-neuromechanical-walking-control-model-using-disturbance-experiments
#17
Seungmoon Song, Hartmut Geyer
Neuromechanical simulations have been used to study the spinal control of human locomotion which involves complex mechanical dynamics. So far, most neuromechanical simulation studies have focused on demonstrating the capability of a proposed control model in generating normal walking. As many of these models with competing control hypotheses can generate human-like normal walking behaviors, a more in-depth evaluation is required. Here, we conduct the more in-depth evaluation on a spinal-reflex-based control model using five representative gait disturbances, ranging from electrical stimulation to mechanical perturbation at individual leg joints and at the whole body...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28377709/the-role-of-architectural-and-learning-constraints-in-neural-network-models-a-case-study-on-visual-space-coding
#18
Alberto Testolin, Michele De Filippo De Grazia, Marco Zorzi
The recent "deep learning revolution" in artificial neural networks had strong impact and widespread deployment for engineering applications, but the use of deep learning for neurocomputational modeling has been so far limited. In this article we argue that unsupervised deep learning represents an important step forward for improving neurocomputational models of perception and cognition, because it emphasizes the role of generative learning as opposed to discriminative (supervised) learning. As a case study, we present a series of simulations investigating the emergence of neural coding of visual space for sensorimotor transformations...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28373839/high-entrainment-constrains-synaptic-depression-levels-of-an-in-vivo-globular-bushy-cell-model
#19
Marek Rudnicki, Werner Hemmert
Globular bushy cells (GBCs) located in the ventral cochlear nucleus are an essential part of the sound localization pathway in the mammalian auditory system. They receive inputs directly from the auditory nerve and are particularly sensitive to temporal cues due to their synaptic and membrane specializations. GBCs act as coincidence detectors for incoming spikes through large synapses-endbulbs of Held-which connect to their soma. Since endbulbs of Held are an integral part of the auditory information conveying and processing pathway, they were extensively studied...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28373838/decoding-time-varying-functional-connectivity-networks-via-linear-graph-embedding-methods
#20
Ricardo P Monti, Romy Lorenz, Peter Hellyer, Robert Leech, Christoforos Anagnostopoulos, Giovanni Montana
An exciting avenue of neuroscientific research involves quantifying the time-varying properties of functional connectivity networks. As a result, many methods have been proposed to estimate the dynamic properties of such networks. However, one of the challenges associated with such methods involves the interpretation and visualization of high-dimensional, dynamic networks. In this work, we employ graph embedding algorithms to provide low-dimensional vector representations of networks, thus facilitating traditional objectives such as visualization, interpretation and classification...
2017: Frontiers in Computational Neuroscience
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