Network synchronization

Network Synchronization in Tonic, Chaotic and Bursting Regimes... 

The implications of individual neuron dynamics on neuronal network synchronization is evident. In Fig. 7.9 (from Schneider et al., unpublished data) this is demonstrated with network simulations (10 x 10 neurons) of nearest neighbor gap-junction coupling. It is illustrated in quite a simple form which, in a similar way, can also be experimentally used with the local mean field potential (LFP). In the simulations LFP simply is the mean potential value of all neurons. In the nonsynchronized state LFP shows tiny, random fluctuations. In the completely in-phase synchronized states the spikes should peak out to their full height... 

Motter, A.E., Zhou, C and Kurths,). Network synchronization, diffusion, and the paradox of heterogeneity. Phys Rev E Stat Nonlin Soft Matter Phys 2005,71 016116. 

Mario Baldi was bom in Cuneo, Italy, on November 9, 1968. He received his M.S. in Electronic Engineering in 1993 from Politecnico di Torino where he is currently Ph.D. student. His research interests include protocols for high speed networks, real-time services over packet switched networks, synchronous packet switched networks, and active networks. 

The instrument/display (client/server) paradigm allows for synchronous and asynchronous analysis, locally or remotely via the Internet or in-house Intranet network. 

The local dynamics of tire systems considered tluis far has been eitlier steady or oscillatory. However, we may consider reaction-diffusion media where tire local reaction rates give rise to chaotic temporal behaviour of tire sort discussed earlier. Diffusional coupling of such local chaotic elements can lead to new types of spatio-temporal periodic and chaotic states. It is possible to find phase-synchronized states in such systems where tire amplitude varies chaotically from site to site in tire medium whilst a suitably defined phase is synclironized tliroughout tire medium 51. Such phase synclironization may play a role in layered neural networks and perceptive processes in mammals. Somewhat suriDrisingly, even when tire local dynamics is chaotic, tire system may support spiral waves... 

Primary generalized seizures are also heterogeneous with respect to their clinical features. Such seizures can impose as absence epilepsy, which is characterized by a brief interruption of consciousness due to highly synchronized neuronal activity involving thalamocortical networks without increases in neuronal firing rate. On the other hand, tonic-clonic convulsions with loss of consciousness are often also primarily generalized. 

Whittington, M. A., Traub, R. D. 8r Jefferys, J. G. (1995). Synchronized oscillations in interneuron networks driven by metabotropic glutamate receptor activation. Nature 373, 612-15. 

Fig. 4.10 Step 2 networks of processes like the left one are transformed into trees shown on the right hand side. Thereby the need of synchronization at the node H258, Q 9351/0/3362 is not necessary any more, because this synchronization is an inher-...

L. Wang and J. Ross, Synchronous neural networks of nonlinear threshold elements with hysteresis, Proc. Natl. Acad. Sci. USA, 87, 988-992 (1990). 

Whittington MA, Traub RD, Jeffreys JG (1995) Synchronized oscillations in interneuron network driven by metabotropic glutamate receptor activation. Natime 373 612-615 Whittington MA, Traub RD, Faulkner HJ, Stanford IM, Jeffreys JG (1997) Recurrent excitatory postsynaptic potentials induced by synchronized fast cortical oscillations. Proc Natl Acad Sci U S A 94 12 198-12 203... 

As can be seen from Fig. 30-32, neurons send "trains" of spikes down their axons. These form synapses with dendrites, usually on dendritic spikes, of a postsynaptic cell.593,1007-1009 However, each such cell typically receives input from thousands of other neurons. At any moment most of these are probably "silent," but others are sending trains of impulses. Among the important questions are "How does the postsynaptic neuron know whether to fire or not " and "What kinds of information, if any, are encoded in the trains of impulses both in the presynaptic inputs and in the output of the postsynaptic neuron "10101011 Part of the answer to the first question is probably that firing occurs if two or more input impulses arrive synchronously,10101012-1014 and if there are not too many inhibitory impulses that damp the response. In the hippocampus a network of neurons electrically coupled via gap junctions may be synchronized to the theta and gamma brain rhythms by high-frequency (150-200 Hz) oscillations.988 See also Fig. 30-15. 

Nicholson, P.J An Introduction to Fiber Optics. Micro-wave J. 26 (June 1991). Nicholson, P.J An Overview of llie Synchronous Optical Network, Microwave J. 24 (December 1991)... 

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