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Axonal anisotropy and connectivity inhomogeneities in 2D networks

July 2012
BMC Neuroscience 13(1)

DOI:10.1186/1471-2202-13-S1-P145

License
CC BY 4.0

Conference: BMC Neuroscience

Authors:

Samora Okujeni

University of Freiburg

Stefan Rotter

Vienna University of Economics and Business

Show all 5 authorsHide

Cultured neuronal networks are an interesting experimental model in which neurons are freed from cortical architecture and plated on microelectrode arrays (MEA). Present in their dynamics are periods of strongly synchronized spiking by the network, termed 'bursting', whose role is not understood but dominates network dynamics and, due to its resistance to attempts to remove it [1], has been suggested to be an inherent feature in their dynamics. Bursts have been demonstrated to contains distinct spatiotemporal motifs, repudiating the possibility that they are random or chaotic activity. However, the speeds of these propagating wavefronts has been measured as 5-100mm/s [2], and hence much faster than can be accounted for by local connectivity [3]. In attempting to represent cultured networks using 2D network models, typical connectivity models, such as small-world, prove to be insufficient for recreating some of the distinct phenomena associated with the dynamics of cultured networks, noticeably the fast propagation speeds. Here, we introduce a simple but biologically plausible connectivity model that is able to reproduce this phenomena. We extend it to incorporate some of the subtle structural inhomogeneities observed experimentally to investigate their implications for network dynamics. We demonstrate that these inhomogeneities strongly facilitate the propagation of activity as well as being responsible for emergence of distinct burst motifs. Importantly, our model confirms that bursts are indeed an inherent feature of such networks, as they are an inescapable by-product of network connectivity and structure.

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P O S T E R P R E S E N T A T I O N Open Access

Axonal anisotropy and connectivity

inhomogeneities in 2D networks

Sarah Jarvs

1,2,3*

, Samora Okujeni

1,2,3

, Steffen Kandler

1,2,3

, Stefan Rotter

1,2

, Ulrich Egert

1,3

From Twenty First Annual Computational Neuroscience Meeting: CNS*2012

Decatur, GA, USA. 21-26 July 2012

Cultured neuronal networks are an interesting experi-

mental model in which neurons are freed from cortical

architecture and plated on microelectrode arrays (MEA).

Present in their dynamics are periods of strongly syn-

chronized spiking by the network, termed ‘bursting’,

whose role is not understood but dominates network

dynamics and, due to its resistance to attempts to remove

it [1], has been suggested to be an inherent feature in

their dynamics. Bursts have been demonstrated to con-

tains distinct spatiotemporal motifs, repudiating the pos-

sibility that they are random or chaotic activity. However,

the speeds of these propagating wavefronts has been

measured as 5-100mm/s [2], and hence much faster than

can be accounted for by local connectivity [3].

In attempting to represent cultured networks using 2D

network models, typical connectivity models, such as

small-world, prove to be insufficient for recreating some

of the distinct phenomena associated with the dynamics

of cultured networks, noticeably the fast propagation

speeds.

Here, we introduce a simple but biologically plausible

connectivity model that is able to reproduce this phenom-

ena. We extend it to incorporate some of the subtle struc-

tural inhomogeneities observed experimentally to

investigate their implications for network dynamics. We

demonstrate that these inhomogeneities strongly facilitate

the propagation of activity as well as being responsible for

emergence of distinct burst motifs. Importantly, our

model confirms that bursts are indeed an inherent feature

of such networks, as they are an inescapable by-product of

network connectivity and structure.

Acknowledgements

This work was supported by the German BMBF (FKZ 01GQ0420) and by the

EC (NEURO, No. 12788).

Author details

Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.

Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany.

Department of Biomicrotechnology, IMTEK, University of Freiburg, Freiburg,

79096, Germany.

Published: 16 July 2012

References

1. Madhavan R, Chao ZC, Wagenaar DA, Bakkum DJ, Potter SM: Multi-site

stimulation quiets network-wide spontaneous bursts and enhances

functional plasticity in cultured cortical networks. Conf Proc IEEE Eng Med

Biol Soc 2006, 1:1593-1596.

2. Maeda E, Robinson HP, Kawana A: The mechanisms of generation and

propagation of synchronized bursting in developing networks of cortical

neurons. J Neurosci 1995, 15:6834-6845.

3. Kitano K, Fukai T: Variability vs synchronicity of neuronal activity in local

cortical network models with different wiring topologoes. J Comput

Neurosci 2007, 23:237-250.

doi:10.1186/1471-2202-13-S1-P145

Cite this article as: Jarvs et al.: Axonal anisotropy and connectivity

inhomogeneities in 2D networks. BMC Neuroscience 2012 13(Suppl 1):

P145.

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* Correspondence: jarvis@bcf.uni-freiburg.de

Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany

Full list of author information is available at the end of the article

Jarvs et al.BMC Neuroscience 2012, 13(Suppl 1):P145

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ResearchGate has not been able to resolve any citations for this publication.

The mechanisms of generation and propagation of synchronized bursting in developing networks of cortical neurons

Article

Full-text available

Oct 1995

The characteristics and mechanisms of synchronized firing in developing networks of cultured cortical neurons were studied using multisite recording through planar electrode arrays (PEAs). With maturation of the network (from 3 to 40 d after plating), the frequency and propagation velocity of bursts increased markedly (approximately from 0.01 to 0.5 Hz and from 5 to 100 mm/sec, respectively), and the sensitivity to extracellular magnesium concentration (0–10 mM) decreased. The source of spontaneous bursts, estimated from the relative delay of onset of activity between electrodes, varied randomly with each burst. Physical separation of synchronously bursting networks into several parts using an ultraviolet laser, divided synchronous bursting into different frequencies and phases in each part. Focal stimulation through the PEA was effective at multiple sites in eliciting bursts, which propagated over the network from the site of stimulation. Stimulated bursts exhibited both an absolute refractory period and a relative refractory period, in which partially propagating bursts could be elicited. Periodic electrical stimulation (at 1 to 30 sec intervals) produced slower propagation velocities and smaller numbers of spikes per burst at shorter stimulation intervals. These results suggest that the generation and propagation of spontaneous synchronous bursts in cultured cortical neurons is governed by the level of spontaneous presynaptic firing, by the degree of connectivity of the network, and by a distributed balance between excitation and recovery processes.

Variability v.s. synchronicity of neuronal activity in local cortical network models with different wiring topologies

Article

Full-text available

Nov 2007

Dynamical behavior of a biological neuronal network depends significantly on the spatial pattern of synaptic connections among neurons. While neuronal network dynamics has extensively been studied with simple wiring patterns, such as all-to-all or random synaptic connections, not much is known about the activity of networks with more complicated wiring topologies. Here, we examined how different wiring topologies may influence the response properties of neuronal networks, paying attention to irregular spike firing, which is known as a characteristic of in vivo cortical neurons, and spike synchronicity. We constructed a recurrent network model of realistic neurons and systematically rewired the recurrent synapses to change the network topology, from a localized regular and a "small-world" network topology to a distributed random network topology. Regular and small-world wiring patterns greatly increased the irregularity or the coefficient of variation (Cv) of output spike trains, whereas such an increase was small in random connectivity patterns. For given strength of recurrent synapses, the firing irregularity exhibited monotonous decreases from the regular to the random network topology. By contrast, the spike coherence between an arbitrary neuron pair exhibited a non-monotonous dependence on the topological wiring pattern. More precisely, the wiring pattern to maximize the spike coherence varied with the strength of recurrent synapses. In a certain range of the synaptic strength, the spike coherence was maximal in the small-world network topology, and the long-range connections introduced in this wiring changed the dependence of spike synchrony on the synaptic strength moderately. However, the effects of this network topology were not really special in other properties of network activity.

Multi-site Stimulation Quiets Network-wide Spontaneous Bursts and Enhances Functional Plasticity in Cultured Cortical Networks

Article

Full-text available

Feb 2006

We culture high-density cortical cultures on multi-electrode arrays (MEAs), which allow us to stimulate and record from thousands of neurons. One of the modes of activity in these high-density cultures is dish-wide synchronized bursting. Unlike in vivo, these synchronized patterns persist for the lifetime of the culture. Such aberrant patterns of activity might be due to the fact that cortical cultures are sensory-deprived and arrested in development. We have devised methods to control this spontaneous activity by multi-electrode electrical stimulation and to study long-term functional neural plasticity, on a background of such burst-quieting stimulation. Here, we investigate whether burst quieting reveals long-term plasticity induced by tetanic stimulation. Spatio-temporal activity patterns (STAPs) that result from probe pulses were clustered and quantified in quieted and non-quieted cultures. Burst-quieted cultures show more tetanus-induced functional change than cultures which are allowed to express spontaneous bursts. The methods developed for this study will help in the understanding of network dynamics and appreciation of their role in long-term plasticity and information processing in the brain.

The mechanism of generation and propagation of synchronized bursting in developing networks of cortical neurons

Article

Nov 1995

The characteristics and mechanisms of synchronized firing in developing networks of cultured cortical neurons were studied using multisite recording through planar electrode arrays (PEAs). With maturation of the network (from 3 to 40 d after plating), the frequency and propagation velocity of bursts increased markedly (approximately from 0.01 to 0.5 Hz and from 5 to 100 mm/sec, respectively), and the sensitivity to extracellular magnesium concentration (0-10 mM) decreased. The source of spontaneous bursts, estimated from the relative delay of onset of activity between electrodes, varied randomly with each burst. Physical separation of synchronously bursting networks into several parts using an ultraviolet laser, divided synchronous bursting into different frequencies and phases in each part. Focal stimulation through the PEA was effective at multiple sites in eliciting bursts, which propagated over the network from the site of stimulation. Stimulated bursts exhibited both an absolute refractory period and a relative refractory period, in which partially propagating bursts could be elicited. Periodic electrical stimulation (at 1 to 30 sec intervals) produced slower propagation velocities and smaller numbers of spikes per burst at shorter stimulation intervals. These results suggest that the generation and propagation of spontaneous synchronous bursts in cultured cortical neurons is governed by the level of spontaneous presynaptic firing, by the degree of connectivity of the network, and by a distributed balance between excitation and recovery processes.

1186/1471-2202-13-S1-P145 Cite this article as: Jarvs et al.: Axonal anisotropy and connectivity inhomogeneities in 2D networks

doi:10.1186/1471-2202-13-S1-P145 Cite this article as: Jarvs et al.: Axonal anisotropy and connectivity inhomogeneities in 2D networks. BMC Neuroscience 2012 13(Suppl 1): P145

Variability vs synchronicity of neuronal activity in local cortical network models with different wiring topologoes

Jan 2007
J COMPUT NEUROSCI
237-250

K Kitano
T Fukai

Kitano K, Fukai T: Variability vs synchronicity of neuronal activity in local cortical network models with different wiring topologoes. J Comput Neurosci 2007, 23:237-250. doi:10.1186/1471-2202-13-S1-P145

Axonal anisotropy and connectivity inhomogeneities in 2D networks

Jan 2012
BMC NEUROSCI
145

Jarvs

Cite this article as: Jarvs et al.: Axonal anisotropy and connectivity inhomogeneities in 2D networks. BMC Neuroscience 2012 13(Suppl 1): P145.

Axonal anisotropy and connectivity inhomogeneities in 2D networks

Abstract

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