scholarly journals Brief wide-field photostimuli evoke and modulate oscillatory reverberating activity in cortical networks

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Rocco Pulizzi ◽  
Gabriele Musumeci ◽  
Chris Van den Haute ◽  
Sebastiaan Van De Vijver ◽  
Veerle Baekelandt ◽  
...  
Keyword(s):  
Wide Field ◽  
Cortical Networks

scholarly journals Rapid fluctuations in functional connectivity of cortical networks encode spontaneous behavior

2021 ◽  
Author(s):  
Hadas Benisty ◽  
Andrew H Moberly ◽  
Sweyta Lohani ◽  
Daniel Barson ◽  
Ronald R Coifman ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Neural Activity ◽  
Large Scale ◽  
Analytical Framework ◽  
Network Activity ◽  
Wide Field ◽  
Time Varying ◽  
Cortical Networks ◽  
Novel Approach ◽  
Spontaneous Behavior

Experimental work across a variety of species has demonstrated that spontaneously generated behaviors are robustly coupled to variation in neural activity within the cerebral cortex. Indeed, functional magnetic resonance imaging (fMRI) data suggest that functional connectivity in cortical networks varies across distinct behavioral states, providing for the dynamic reorganization of patterned activity. However, these studies generally lack the temporal resolution to establish links between cortical signals and the continuously varying fluctuations in spontaneous behavior typically observed in awake animals. Here, we took advantage of recent developments in wide-field, mesoscopic calcium imaging to monitor neural activity across the neocortex of awake mice. Applying a novel approach to quantifying time-varying functional connectivity, we show that spontaneous behaviors are more accurately represented by fast changes in the correlational structure versus the magnitude of large-scale network activity. Moreover, dynamic functional connectivity reveals subnetworks that are not predicted by traditional anatomical atlas-based parcellation of the cortex. These results provide insight into how behavioral information is represented across the mammalian neocortex and demonstrate a new analytical framework for investigating time-varying functional connectivity in neural networks.

scholarly journals Assessing the role of inhibition in stabilizing neocortical networks requires large-scale perturbation of the inhibitory population

2017 ◽  
Author(s):  
Sadra Sadeh ◽  
R. Angus Silver ◽  
Thomas Mrsic-Flogel ◽  
Dylan Richard Muir
Keyword(s):  
Large Scale ◽  
Computational Models ◽  
Network Models ◽  
Operating Regime ◽  
High Gain ◽  
Inhibitory Neurons ◽  
Wide Field ◽  
Cortical Networks ◽  
Inhibitory Feedback ◽  
Inhibitory Population

AbstractNeurons within cortical microcircuits are interconnected with recurrent excitatory synaptic connections that are thought to amplify signals (Douglas and Martin, 2007), form selective subnetworks (Ko et al., 2011) and aid feature discrimination. Strong inhibition (Haider et al., 2013) counterbalances excitation, enabling sensory features to be sharpened and represented by sparse codes (Willmore et al., 2011). This “balance” between excitation and inhibition makes it difficult to assess the strength, or gain, of recurrent excitatory connections within cortical networks, which is key to understanding their operational regime and the computations they perform. Networks of neurons combining an unstable high-gain excitatory population with stabilizing inhibitory feedback are known as inhibition-stabilized networks (ISNs; Tsodyks et al. 1997). Theoretical studies using reduced network models predict that ISNs produce paradoxical responses to perturbation, but experimental perturbations failed to find evidence for ISNs in cortex (Atallah et al., 2012). We re-examined this question by investigating how cortical network models consisting of many neurons behave following perturbations, and found that results obtained from reduced network models fail to predict responses to perturbations in more realistic networks. Our models predict that a large proportion of the inhibitory network must be perturbed in order to robustly detect an ISN regime in cortex. We propose that wide-field optogenetic suppression of inhibition under a promoter targeting all inhibitory neurons may provide a perturbation of sufficient strength to reveal the operating regime of cortex. Our results suggest that detailed computational models of optogenetic perturbations are necessary to interpret the results of experimental paradigms.Significance statementMany useful computational mechanisms proposed for cortex require local excitatory recurrence to be very strong, such that local inhibitory feedback is necessary to avoid epileptiform runaway activity (an “inhibition-stabilized network” or “ISN” regime). However, recent experimental results suggest this regime may not exist in cortex. We simulated activity perturbations in cortical networks of increasing realism, and found that in order to detect ISN-like properties in cortex, large proportions of the inhibitory population must be perturbed. Current experimental methods for inhibitory perturbation are unlikely to satisfy this requirement, implying that existing experimental observations are inconclusive about the computational regime of cortex. Our results suggest that new experimental designs, targetting a majority of inhibitory neurons, may be able to resolve this question.

scholarly journals Long-range order from local interactions: organization and development of distributed cortical networks

2018 ◽  
Author(s):  
Gordon B. Smith ◽  
Bettina Hein ◽  
David E. Whitney ◽  
David Fitzpatrick ◽  
Matthias Kaschube
Keyword(s):  
Visual Cortex ◽  
Spontaneous Activity ◽  
Long Range ◽  
Network Structure ◽  
Large Scale ◽  
Wide Field ◽  
Cortical Networks ◽  
Subsequent Formation ◽  
Correlated Activity

The cortical networks that underlie behavior exhibit an orderly functional organization at local and global scales, which is readily evident in the visual cortex of carnivores and primates1-6. Here, neighboring columns of neurons represent the full range of stimulus orientations and contribute to distributed networks spanning several millimeters2,7-11. However, the principles governing functional interactions that bridge this fine-scale functional architecture and distant network elements are unclear, and the emergence of these network interactions during development remains unexplored. Here, by using in vivo wide-field and 2-photon calcium imaging of spontaneous activity patterns in mature ferret visual cortex, we find widespread and specific modular correlation patterns that accurately predict the local structure of visually-evoked orientation columns from the spontaneous activity of neurons that lie several millimeters away. The large-scale networks revealed by correlated spontaneous activity show abrupt ‘fractures’ in continuity that are in tight register with evoked orientation pinwheels. Chronic in vivo imaging demonstrates that these large-scale modular correlation patterns and fractures are already present at early stages of cortical development and predictive of the mature network structure. Silencing feed-forward drive through either retinal or thalamic blockade does not affect network structure suggesting a cortical origin for this large-scale correlated activity, despite the immaturity of long-range horizontal network connections in the early cortex. Using a circuit model containing only local connections, we demonstrate that such a circuit is sufficient to generate large-scale correlated activity, while also producing correlated networks showing strong fractures, a reduced dimensionality, and an elongated local correlation structure, all in close agreement with our empirical data. These results demonstrate the precise local and global organization of cortical networks revealed through correlated spontaneous activity and suggest that local connections in early cortical circuits may generate structured long-range network correlations that underlie the subsequent formation of visually-evoked distributed functional networks.

scholarly journals Wide field-of-view, twin-region two-photon imaging across extended cortical networks

2014 ◽  
Author(s):  
Jeffrey N. Stirman ◽  
Ikuko T. Smith ◽  
Michael W. Kudenov ◽  
Spencer L. Smith
Keyword(s):  
Imaging System ◽  
Field Of View ◽  
Wide Field ◽  
Cortical Networks ◽  
Two Photon ◽  
Cortical Areas ◽  
Cellular Resolution ◽  
Wide Field Of View ◽  
Photon Imaging ◽  
Two Photon Imaging

We demonstrate a two-photon imaging system with corrected optics including a custom objective that provides cellular resolution across a 3.5 mm field of view (9.6 mm^2). Temporally multiplexed excitation pathways can be independently repositioned in XY and Z to simultaneously image regions within the expanded field of view. We used this new imaging system to measure activity correlations between neurons in different cortical areas in awake mice.

STM studies of crystal growth

1991 ◽  
Vol 49 ◽  
pp. 374-375
Author(s):  
M. G. Lagally
Keyword(s):  
Crystal Growth ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Sputter Deposition ◽  
Field Of View ◽  
Scanning Tunneling ◽  
Wide Field ◽  
Tunneling Microscopy ◽  
Wide Field Of View ◽  
The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

Wide-field subsecond temporal resolution optical monitoring systems for detection and study of cosmic hazards

2013 ◽  
Vol 183 (8) ◽  
pp. 888-894
Author(s):  
G.M. Beskin ◽  
S.V. Karpov ◽  
V.L. Plokhotnichenko ◽  
S.F. Bondar ◽  
A.V. Perkov ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Monitoring Systems ◽  
Wide Field ◽  
Optical Monitoring

Discovery of the fast optical variability of GRB 080319B and the prospects for wide-field optical monitoring with high time resolution

2010 ◽  
Vol 180 (4) ◽  
pp. 424 ◽  
Author(s):  
G.M. Beskin ◽  
S.V. Karpov ◽  
S.F. Bondar ◽  
V.L. Plokhotnichenko ◽  
A. Guarnieri ◽  
...  
Keyword(s):  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Optical Variability ◽  
Wide Field ◽  
Optical Monitoring
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