Unique Characterization of Spatiotemporal Neuronal Network Activity

Mapping Intimacies ◽

10.1101/2021.08.16.456546 ◽

2021 ◽

Author(s):

Sarita S. Deshpande ◽

Graham Smith ◽

Wim van Drongelen

Keyword(s):

Neural Activity ◽

Phase Relationship ◽

Building Blocks ◽

Network Activity ◽

Third Order ◽

Triple Correlation ◽

Neuronal Network Activity ◽

Flow Of Information ◽

Spiking Activity

We apply the Triple Correlation Uniqueness (TCU) theorem to the most basic representation of network spiking activity, the raster, to prove that third-order (triple) correlation uniquely characterizes spiking activity in the brain. As a consequence, the three-node (triple) motifs comprising the triple correlation are fundamental building blocks of neuronal activity. By analysing the putative flow of information in these motifs, we group all possible motifs into fourteen motif-classes. These motif-classes embody well-known and well-studied properties in neuroscience, e.g. spike rate, local dynamics, synchrony, feedback, feedforward, convergence, and divergence. We show that motifs with some of these properties---divergence, convergence, and feedforward---are far more prevalent in the triple correlation; and thus, these properties contribute more to characterizing neural activity than do the other properties. In the frequency domain, the triple correlation is the bispectrum, which characterizes the phase-relationship between spike trains and the relationships between frequency bands. We apply these analyses to example rasters to illustrate the dependence of our characterization on the firing patterns underlying neural activity.

Download Full-text

Synthesis and Characterization of TiO2 -Nb2O5 Borosilicate Glasses for Nonlinear Optical Waveguides

MRS Proceedings ◽

10.1557/proc-88-101 ◽

1986 ◽

Vol 88 ◽

Cited By ~ 4

Author(s):

E. M. Vogel ◽

S. R. Fribérg ◽

L. Jackel ◽

P. W. Smith

Keyword(s):

Optical Waveguides ◽

Nonlinear Optical ◽

Building Blocks ◽

Optical Nonlinearity ◽

Borosilicate Glasses ◽

Optical Logic ◽

Third Order ◽

All Optical ◽

Nonlinear Index

ABSTRACTNonlinear optical glasses with fast responding nonlinearities and very low absorption are promising materials for use in ultra-fast (picosecond) all-optical switches. We have synthesized a TiO2 Nb2O5. B2O3 Na2O SiO2 glass with the intention of optimizing both the third order optical nonlinearity and suitability for fabrication of optical waveguides. The nonlinear index coefficient n2 for this glass composition was found to be 4X 10-19 m2/W, a factor of two greater than the largest value previously reported for commercially available TiO2-silicate glasses. Optical waveguides with a maximum index change of Δn = 0.12 were made using silver-sodium ion exchange. These waveguides may become building blocks for future all-optical logic elements and circuits.

Download Full-text

KCNQ potassium channels are critical determinants of neuronal network activity in neonatal mouse brain

Neuropediatrics ◽

10.1055/s-0029-1215870 ◽

2008 ◽

Vol 39 (05) ◽

Author(s):

A Neu ◽

Q Le ◽

I Hanganu ◽

D Isbrandt

Keyword(s):

Potassium Channels ◽

Mouse Brain ◽

Neuronal Network ◽

Neonatal Mouse ◽

Network Activity ◽

Neuronal Network Activity

Download Full-text

Desynchronisation of neuronal network activity in traumatic brain injury

Klinische Neurophysiologie ◽

10.1055/s-2008-1072810 ◽

2008 ◽

Vol 39 (01) ◽

Author(s):

F Otto ◽

J Opatz ◽

R Hartmann ◽

D Willbold ◽

E Donauer ◽

...

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Neuronal Network ◽

Network Activity ◽

Neuronal Network Activity

Download Full-text

Dementia with Lewy bodies—associated ß-synuclein mutations V70M and P123H cause mutation-specific neuropathological lesions

Human Molecular Genetics ◽

10.1093/hmg/ddab036 ◽

2021 ◽

Author(s):

Maryna Psol ◽

Sofia Guerin Darvas ◽

Kristian Leite ◽

Sameehan U Mahajani ◽

Mathias Bähr ◽

...

Keyword(s):

Neuronal Network ◽

Dementia With Lewy Bodies ◽

Lewy Bodies ◽

Sporadic Case ◽

Network Activity ◽

Proteinase K ◽

Neuronal Network Activity ◽

Distinct Disease

Abstract ß-Synuclein (ß-Syn) has long been considered to be an attenuator for the neuropathological effects caused by the Parkinson’s disease-related α-Synuclein (α-Syn) protein. However, recent studies demonstrated that overabundant ß-Syn can form aggregates and induce neurodegeneration in CNS neurons in vitro and in vivo, albeit at a slower pace as compared to α-Syn. Here we demonstrate that ß-Syn mutants V70M, detected in a sporadic case of Dementia with Lewy Bodies (DLB), and P123H, detected in a familial case of DLB, robustly aggravate the neurotoxic potential of ß-Syn. Intriguingly, the two mutations trigger mutually exclusive pathways. ß-Syn V70M enhances morphological mitochondrial deterioration and degeneration of dopaminergic and non-dopaminergic neurons, but has no influence on neuronal network activity. Conversely, ß-Syn P123H silences neuronal network activity, but does not aggravate neurodegeneration. ß-Syn WT, V70M and P123H formed proteinase K (PK) resistant intracellular fibrils within neurons, albeit with less stable C-termini as compared to α-Syn. Under cell free conditions, ß-Syn V70M demonstrated a much slower pace of fibril formation as compared to WT ß-Syn, and P123H fibrils present with a unique phenotype characterized by large numbers of short, truncated fibrils. Thus, it is possible that V70M and P123H cause structural alterations in ß-Syn, that are linked to their distinct neuropathological profiles. The extent of the lesions caused by these neuropathological profiles is almost identical to that of overabundant α-Syn, and thus likely to be directly involved into etiology of DLB. Over all, this study provides insights into distinct disease mechanisms caused by mutations of ß-Syn.

Download Full-text

On the similarity to nonnegative and Metzler Hessenberg forms

Special Matrices ◽

10.1515/spma-2020-0140 ◽

2021 ◽

Vol 10 (1) ◽

pp. 1-8

Author(s):

Christian Grussler ◽

Anders Rantzer

Keyword(s):

Standard Form ◽

Complete Characterization ◽

Nonnegative Matrices ◽

Positive Systems ◽

Third Order ◽

Hessenberg Form ◽

Hessenberg Matrices ◽

Open Question ◽

Order Continuous

Abstract We address the issue of establishing standard forms for nonnegative and Metzler matrices by considering their similarity to nonnegative and Metzler Hessenberg matrices. It is shown that for dimensions n 3, there always exists a subset of nonnegative matrices that are not similar to a nonnegative Hessenberg form, which in case of n = 3 also provides a complete characterization of all such matrices. For Metzler matrices, we further establish that they are similar to Metzler Hessenberg matrices if n 4. In particular, this provides the first standard form for controllable third order continuous-time positive systems via a positive controller-Hessenberg form. Finally, we present an example which illustrates why this result is not easily transferred to discrete-time positive systems. While many of our supplementary results are proven in general, it remains an open question if Metzler matrices of dimensions n 5 remain similar to Metzler Hessenberg matrices.

Download Full-text

Neuromodulation of Astrocytic K+ Clearance

International Journal of Molecular Sciences ◽

10.3390/ijms22052520 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2520

Author(s):

Alba Bellot-Saez ◽

Rebecca Stevenson ◽

Orsolya Kékesi ◽

Evgeniia Samokhina ◽

Yuval Ben-Abu ◽

...

Keyword(s):

Oscillatory Behavior ◽

Network Activity ◽

Oscillatory Activity ◽

Extracellular Potassium ◽

Uptake Mechanism ◽

Kir Channels ◽

Neuronal Network Activity ◽

Clearance Process ◽

Spatial Buffering ◽

The Impact

Potassium homeostasis is fundamental for brain function. Therefore, effective removal of excessive K+ from the synaptic cleft during neuronal activity is paramount. Astrocytes play a key role in K+ clearance from the extracellular milieu using various mechanisms, including uptake via Kir channels and the Na+-K+ ATPase, and spatial buffering through the astrocytic gap-junction coupled network. Recently we showed that alterations in the concentrations of extracellular potassium ([K+]o) or impairments of the astrocytic clearance mechanism affect the resonance and oscillatory behavior of both the individual and networks of neurons. These results indicate that astrocytes have the potential to modulate neuronal network activity, however, the cellular effectors that may affect the astrocytic K+ clearance process are still unknown. In this study, we have investigated the impact of neuromodulators, which are known to mediate changes in network oscillatory behavior, on the astrocytic clearance process. Our results suggest that while some neuromodulators (5-HT; NA) might affect astrocytic spatial buffering via gap-junctions, others (DA; Histamine) primarily affect the uptake mechanism via Kir channels. These results suggest that neuromodulators can affect network oscillatory activity through parallel activation of both neurons and astrocytes, establishing a synergistic mechanism to maximize the synchronous network activity.

Download Full-text

Numerical Characterization of Cohesive and Non-Cohesive ‘Sediments’ under Different Consolidation States Using 3D DEM Triaxial Experiments

Processes ◽

10.3390/pr8101252 ◽

2020 ◽

Vol 8 (10) ◽

pp. 1252

Author(s):

Hadar Elyashiv ◽

Revital Bookman ◽

Lennart Siemann ◽

Uri ten Brink ◽

Katrin Huhn

Keyword(s):

Mechanical Response ◽

Burial Depth ◽

Cohesive Sediments ◽

Third Order ◽

First Order ◽

Numerical Characterization ◽

Response To Stress ◽

Bond Strengths ◽

Individual Bond

The Discrete Element Method has been widely used to simulate geo-materials due to time and scale limitations met in the field and laboratories. While cohesionless geo-materials were the focus of many previous studies, the deformation of cohesive geo-materials in 3D remained poorly characterized. Here, we aimed to generate a range of numerical ‘sediments’, assess their mechanical response to stress and compare their response with laboratory tests, focusing on differences between the micro- and macro-material properties. We simulated two endmembers—clay (cohesive) and sand (cohesionless). The materials were tested in a 3D triaxial numerical setup, under different simulated burial stresses and consolidation states. Variations in particle contact or individual bond strengths generate first order influence on the stress–strain response, i.e., a different deformation style of the numerical sand or clay. Increased burial depth generates a second order influence, elevating peak shear strength. Loose and dense consolidation states generate a third order influence of the endmember level. The results replicate a range of sediment compositions, empirical behaviors and conditions. We propose a procedure to characterize sediments numerically. The numerical ‘sediments’ can be applied to simulate processes in sediments exhibiting variations in strength due to post-seismic consolidation, bioturbation or variations in sedimentation rates.

Download Full-text