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https://www.readbyqxmd.com/read/29240769/specific-excitatory-connectivity-for-feature-integration-in-mouse-primary-visual-cortex
#1
Dylan R Muir, Patricia Molina-Luna, Morgane M Roth, Fritjof Helmchen, Björn M Kampa
Local excitatory connections in mouse primary visual cortex (V1) are stronger and more prevalent between neurons that share similar functional response features. However, the details of how functional rules for local connectivity shape neuronal responses in V1 remain unknown. We hypothesised that complex responses to visual stimuli may arise as a consequence of rules for selective excitatory connectivity within the local network in the superficial layers of mouse V1. In mouse V1 many neurons respond to overlapping grating stimuli (plaid stimuli) with highly selective and facilitatory responses, which are not simply predicted by responses to single gratings presented alone...
December 14, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29238299/the-htm-spatial-pooler-a-neocortical-algorithm-for-online-sparse-distributed-coding
#2
Yuwei Cui, Subutai Ahmad, Jeff Hawkins
Hierarchical temporal memory (HTM) provides a theoretical framework that models several key computational principles of the neocortex. In this paper, we analyze an important component of HTM, the HTM spatial pooler (SP). The SP models how neurons learn feedforward connections and form efficient representations of the input. It converts arbitrary binary input patterns into sparse distributed representations (SDRs) using a combination of competitive Hebbian learning rules and homeostatic excitability control...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/29230640/new-class-of-reduced-computationally-efficient-neuronal-models-for-large-scale-simulations-of-brain-dynamics
#3
Maxim Komarov, Giri Krishnan, Sylvain Chauvette, Nikolai Rulkov, Igor Timofeev, Maxim Bazhenov
During slow-wave sleep, brain electrical activity is dominated by the slow (< 1 Hz) electroencephalogram (EEG) oscillations characterized by the periodic transitions between active (or Up) and silent (or Down) states in the membrane voltage of the cortical and thalamic neurons. Sleep slow oscillation is believed to play critical role in consolidation of recent memories. Past computational studies, based on the Hodgkin-Huxley type neuronal models, revealed possible intracellular and network mechanisms of the neuronal activity during sleep, however, they failed to explore the large-scale cortical network dynamics depending on collective behavior in the large populations of neurons...
December 12, 2017: Journal of Computational Neuroscience
https://www.readbyqxmd.com/read/29230055/impaired-path-integration-in-mice-with-disrupted-grid-cell-firing
#4
Mariana Gil, Mihai Ancau, Magdalene I Schlesiger, Angela Neitz, Kevin Allen, Rodrigo J De Marco, Hannah Monyer
Path integration (PI) is a highly conserved, self-motion-based navigation strategy. Since the discovery of grid cells in the medial entorhinal cortex, neurophysiological data and computational models have suggested that these neurons serve PI. However, more direct empirical evidence supporting this hypothesis has been missing due to a lack of selective manipulations of grid cell activity and suitable behavioral assessments. Here we report that selective disruption of grid cell activity in mice can be achieved by removing NMDA glutamate receptors from the retro-hippocampal region and that disrupted grid cell firing accounts for impaired PI performance...
December 11, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/29229704/a-unifying-motif-for-spatial-and-directional-surround-suppression
#5
Liu D Liu, Kenneth D Miller, Christopher C Pack
In the visual system, the response to a stimulus in a neuron's receptive field can be modulated by stimulus context, and the strength of these contextual influences vary with stimulus intensity. Recent work has shown how a theoretical model, the stabilized supralinear network (SSN), can account for such modulatory influences, using a small set of computational mechanisms. While the predictions of the SSN have been confirmed in primary visual cortex (V1), its computational principles apply with equal validity to any cortical structure...
December 11, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29223682/neocortical-origin-and-progression-of-gray-matter-atrophy-in-nonamnestic-alzheimer-s-disease
#6
Jeffrey S Phillips, Fulvio Da Re, Laynie Dratch, Sharon X Xie, David J Irwin, Corey T McMillan, Sanjeev N Vaishnavi, Carlo Ferrarese, Edward B Lee, Leslie M Shaw, John Q Trojanowski, David A Wolk, Murray Grossman
Amnestic Alzheimer's disease (AD) is characterized by early atrophy of the hippocampus and medial temporal lobes before spreading to the neocortex. In contrast, nonamnestic Alzheimer's patients have relative sparing of the hippocampus, but the pattern in which the disease spreads is unclear. We examined spreading disease in nonamnestic AD using a novel magnetic resonance imaging-based analysis adapted from pathologic staging studies, applied here to cross-sectional imaging data. We selected 240 T1-weighted scans from 129 patients with pathology confirmed by autopsy or cerebrospinal fluid, and atrophy maps were computed relative to 238 scans from 115 elderly controls...
November 21, 2017: Neurobiology of Aging
https://www.readbyqxmd.com/read/29220308/learning-midlevel-auditory-codes-from-natural-sound-statistics
#7
Wiktor Młynarski, Josh H McDermott
Interaction with the world requires an organism to transform sensory signals into representations in which behaviorally meaningful properties of the environment are made explicit. These representations are derived through cascades of neuronal processing stages in which neurons at each stage recode the output of preceding stages. Explanations of sensory coding may thus involve understanding how low-level patterns are combined into more complex structures. To gain insight into such midlevel representations for sound, we designed a hierarchical generative model of natural sounds that learns combinations of spectrotemporal features from natural stimulus statistics...
December 8, 2017: Neural Computation
https://www.readbyqxmd.com/read/29217687/role-of-the-axon-initial-segment-in-the-control-of-spontaneous-frequency-of-nigral-dopaminergic-neurons-in-vivo
#8
Rodrigo C Meza, Luciana López-Jury, Carmen C Canavier, Pablo Henny
The spontaneous tonic discharge activity of nigral dopamine neurons plays a fundamental role in dopaminergic signaling. To investigate the role of neuronal morphology and architecture with respect to spontaneous activity in this population, we visualized the 3D structure of the axon initial segment (AIS) along with the entire somatodendritic domain of adult male mouse dopaminergic neurons, previously recorded in vivo We observed a positive correlation of the firing rate with both proximity and size of the AIS...
December 6, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29213234/cognitive-mapping-based-on-conjunctive-representations-of-space-and-movement
#9
Taiping Zeng, Bailu Si
It is a challenge to build robust simultaneous localization and mapping (SLAM) system in dynamical large-scale environments. Inspired by recent findings in the entorhinal-hippocampal neuronal circuits, we propose a cognitive mapping model that includes continuous attractor networks of head-direction cells and conjunctive grid cells to integrate velocity information by conjunctive encodings of space and movement. Visual inputs from the local view cells in the model provide feedback cues to correct drifting errors of the attractors caused by the noisy velocity inputs...
2017: Frontiers in Neurorobotics
https://www.readbyqxmd.com/read/29212924/robust-mixture-modeling-reveals-category-free-selectivity-in-reward-region-neuronal-ensembles
#10
Tommy C Blanchard, Steve Piantadosi, Benjamin Y Hayden
Classification of neurons into clusters based on their response properties is an important tool for gaining insight into neural computations. However, it remains unclear to what extent neurons fall naturally into discrete functional categories. We developed a Bayesian method that models the tuning properties of neural populations as a mixture of multiple types of task-relevant response patterns. We applied this method to data from several cortical and striatal regions in economic choice tasks. In all cases, neurons fell into only two clusters: one multiple selectivity cluster containing all cells driven by task variables of interest and another of no selectivity for those variables...
December 6, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29212920/phasic-and-tonic-cell-types-in-the-zebra-finch-auditory-caudal-mesopallium
#11
Andrew N Chen, C Daniel Meliza
The caudal mesopallium (CM) is a cortical-level area in the songbird auditory pathway where selective, invariant responses to familiar songs emerge. To characterize the cell types that perform this computation, we made whole-cell recordings from brain slices in juvenile zebra finches (Taeniopygia guttata) of both sexes. We found three groups of putatively excitatory neurons with distinct firing patterns. Tonic cells produced sustained responses to depolarizing step currents, phasic cells produced only a few spikes at the onset, and an intermediate group was also phasic but responded for up to a few hundred ms...
December 6, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29211994/membrane-tension-inhibits-rapid-and-slow-endocytosis-in-secretory-cells
#12
Xin-Sheng Wu, Sharon Elias, Huisheng Liu, Johanna Heureaux, Peter J Wen, Allen P Liu, Michael M Kozlov, Ling-Gang Wu
Endocytosis generates spherical or ellipsoid-like vesicles from the plasma membrane, which recycles vesicles that fuse with the plasma member during exocytosis in neurons and endocrine secretory cells. Although tension in the plasma membrane is generally considered to be an important factor in regulating endocytosis, whether membrane tension inhibits or facilitates endocytosis remains debated in the endocytosis field, and has been rarely studied for vesicular endocytosis in secretory cells. Here we report that increasing membrane tension by adjusting osmolarity inhibited both the rapid (a few seconds) and slow (tens of seconds) endocytosis in calyx-type nerve terminals containing conventional active zones and in neuroendocrine chromaffin cells...
December 5, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29209178/a-three-layer-network-model-of-direction-selective-circuits-in-the-optic-tectum
#13
Fatima Abbas, Marcus A Triplett, Geoffrey J Goodhill, Martin P Meyer
The circuit mechanisms that give rise to direction selectivity in the retina have been studied extensively but how direction selectivity is established in retinorecipient areas of the brain is less well understood. Using functional imaging in larval zebrafish we examine how the direction of motion is encoded by populations of neurons at three layers of the optic tectum; retinal ganglion cell axons (RGCs), a layer of superficial inhibitory interneurons (SINs), and periventricular neurons (PVNs), which constitute the majority of neurons in the tectum...
2017: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/29208230/learning-from-connectomics-on-the-fly
#14
REVIEW
Philipp Schlegel, Marta Costa, Gregory Sxe Jefferis
Parallels between invertebrates and vertebrates in nervous system development, organisation and circuits are powerful reasons to use insects to study the mechanistic basis of behaviour. The last few years have seen the generation in Drosophila melanogaster of very large light microscopy data sets, genetic driver lines and tools to report or manipulate neural activity. These resources in conjunction with computational tools are enabling large scale characterisation of neuronal types and their functional properties...
December 2017: Current Opinion in Insect Science
https://www.readbyqxmd.com/read/29206224/efficient-encoding-of-motion-is-mediated-by-gap-junctions-in-the-fly-visual-system
#15
Siwei Wang, Alexander Borst, Noga Zaslavsky, Naftali Tishby, Idan Segev
Understanding the computational implications of specific synaptic connectivity patterns is a fundamental goal in neuroscience. In particular, the computational role of ubiquitous electrical synapses operating via gap junctions remains elusive. In the fly visual system, the cells in the vertical-system network, which play a key role in visual processing, primarily connect to each other via axonal gap junctions. This network therefore provides a unique opportunity to explore the functional role of gap junctions in sensory information processing...
December 4, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29196762/neuronal-mechanisms-underlying-differences-in-spatial-resolution-between-darks-and-lights-in-human-vision
#16
Carmen Pons, Reece Mazade, Jianzhong Jin, Mitchell W Dul, Qasim Zaidi, Jose-Manuel Alonso
Artists and astronomers noticed centuries ago that humans perceive dark features in an image differently from light ones; however, the neuronal mechanisms underlying these dark/light asymmetries remained unknown. Based on computational modeling of neuronal responses, we have previously proposed that such perceptual dark/light asymmetries originate from a luminance/response saturation within the ON retinal pathway. Consistent with this prediction, here we show that stimulus conditions that increase ON luminance/response saturation (e...
December 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/29194457/olfactory-coding-in-the-turbulent-realm
#17
Vincent Jacob, Christelle Monsempès, Jean-Pierre Rospars, Jean-Baptiste Masson, Philippe Lucas
Long-distance olfactory search behaviors depend on odor detection dynamics. Due to turbulence, olfactory signals travel as bursts of variable concentration and spacing and are characterized by long-tail distributions of odor/no-odor events, challenging the computing capacities of olfactory systems. How animals encode complex olfactory scenes to track the plume far from the source remains unclear. Here we focus on the coding of the plume temporal dynamics in moths. We compare responses of olfactory receptor neurons (ORNs) and antennal lobe projection neurons (PNs) to sequences of pheromone stimuli either with white-noise patterns or with realistic turbulent temporal structures simulating a large range of distances (8 to 64 m) from the odor source...
December 1, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29193076/resurgent-sodium-current-promotes-action-potential-firing-in-the-avian-auditory-brainstem
#18
Hui Hong, Ting Lu, Xiaoyu Wang, Yuan Wang, Jason Tait Sanchez
Auditory brainstem neurons are functionally primed to fire action potentials (APs) at markedly high-rates in order to rapidly encode acoustic information of sound. This specialization is critical for survival and the comprehension of behaviourally relevant communication functions, including sound localization and understanding speech in noise. Here, we investigated underlying ion channel mechanisms essential for high-rate AP firing in neurons of the chicken nucleus magnocellularis (NM) - the avian analog of bushy cells of the mammalian anteroventral cochlear nucleus...
November 28, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29192377/how-does-transient-signaling-input-affect-the-spike-timing-of-postsynaptic-neuron-near-the-threshold-regime-an-analytical-study
#19
Safura Rashid Shomali, Majid Nili Ahmadabadi, Hideaki Shimazaki, Seyyed Nader Rasuli
The noisy threshold regime, where even a small set of presynaptic neurons can significantly affect postsynaptic spike-timing, is suggested as a key requisite for computation in neurons with high variability. It also has been proposed that signals under the noisy conditions are successfully transferred by a few strong synapses and/or by an assembly of nearly synchronous synaptic activities. We analytically investigate the impact of a transient signaling input on a leaky integrate-and-fire postsynaptic neuron that receives background noise near the threshold regime...
December 1, 2017: Journal of Computational Neuroscience
https://www.readbyqxmd.com/read/29190695/high-accuracy-detection-of-early-parkinson-s-disease-using-multiple-characteristics-of-finger-movement-while-typing
#20
Warwick R Adams
Parkinson's Disease (PD) is a progressive neurodegenerative movement disease affecting over 6 million people worldwide. Loss of dopamine-producing neurons results in a range of both motor and non-motor symptoms, however there is currently no definitive test for PD by non-specialist clinicians, especially in the early disease stages where the symptoms may be subtle and poorly characterised. This results in a high misdiagnosis rate (up to 25% by non-specialists) and people can have the disease for many years before diagnosis...
2017: PloS One
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