Spatially Correlated Noise Effects on Coherence Resonance in Excitable Cell Networks

1. The effect of spatially correlated noiseon coherence resonancein a network of excitable cells 권오규, 조항현, 문희태 2005년 8월 8일

2. Stochastic Resonance • Single system • Single bistable system with periodic signal(=SR) • Single excitable system without external signal(=CR) • Extended system • Array enhance • Spatial independence noise enhance • Network topology

3. Our Model • Combine network effect and noise correlation effect noise elements network • As network randomness increases, • we can change both network structure and noise correlation

4. …… …… Model equation • FitzHugh-Nagumo neuron • Spatially correlated noise Independent gaussian random variables …… ……

5. Mean of firing interval S = Variance of firing interval 1 = Normalized Variance of firing interval Coherence measure • Degree of temporal coherence firing interval Larger S implies that firing intervals are more uniform

6. Results 1/4 • Increasing noise correlation when • If there is noise correlation, neurons begin to fire smaller noise for relatively strong coupling When regular network

7. Results 2/4 • Increasing long range interaction when • If coupling strength is not strong, long range connection further enhance coherent motion • For strong coupling, excitation is more difficult by long range connection When completely uncorrelated noise

8. Results 3/4 • Maximum coherence Smvs. randomness p very weak coupling optimal coupling very strong coupling rather weak coupling rather strong coupling

9. Results 4/4 Quantity of network topology rather strong coupling very strong coupling Dopt as a function of p

10. Conclusion • We can see diverse CR phenomena as a function of p for various coupling strength • We can obtain abrupt change of CR near p=0.1 • Clustered structure of the network is drastically fractured near p=0.1 • Spatially correlated noise enforces the role of the clustered structure