Yılmaz, Ergin | Baysal, Veli | Özer, Mahmut

Article | 2015 | Physics Letters, Section A: General, Atomic and Solid State Physics379 ( 26-27 ) , pp.1594 - 1599

We investigate the effects of time-periodic coupling strength on the temporal coherence or firing regularity of a scale-free network consisting of stochastic Hodgkin-Huxley (H-H) neurons. The temporal coherence exhibits a resonance-like behavior depending on the cell size or the channel noise intensity. The best temporal coherence requires an optimal channel noise intensity, and this coherence can be significantly increased by time-periodic coupling strength when its frequency matches the integer multiples of the intrinsic subthreshold oscillation frequency of H-H neuron. Particularly, we find the multiple-coherence resonance depend . . .ing on frequency of time-periodic coupling strength at the optimal noise intensity. We also obtain a resonance-like dependence of temporal coherence on the amplitude of time-periodic coupling strength. Additionally, we investigate the effects of average degree on the temporal coherence and find that the temporal coherence exhibits a resonance-like behavior with respect to the network average degree, indicating that the best regularity requires an optimal average degree. © 2015 Elsevier B.V. All rights reserved Daha fazlası Daha az

Özer, Mahmut | Ekmekçi, N. Hakan

Article | 2005 | Physics Letters, Section A: General, Atomic and Solid State Physics338 ( 2 ) , pp.150 - 154

Ion channel noise that stems from the stochastic nature of the channel has important effects on neuronal dynamics. In this context, we examine the effect of the channel noise on the time-course of recovery from inactivation of sodium channels by using a stochastic extension of the Hodgkin-Huxley model. We show that the channel noise provides both some amount of the non-inactivated channels and a smaller time-course for recovering from inactivation leading to an increased maximal sodium conductance compared to deterministic one. © 2005 Elsevier B.V. All rights reserved.

Özer, Mahmut | Perc, Matjaž | Uzuntarla, Muhammet | Koklukaya, Etem

Article | 2010 | NeuroReport21 ( 5 ) , pp.338 - 343

We determine under which conditions the propagation of weak periodic signals through a feedforward Hodgkin-Huxley neuronal network is optimal. We find that successive neuronal layers are able to amplify weak signals introduced to the neurons forming the first layer only above a certain intensity of intrinsic noise. Furthermore, we show that as low as 4% of all possible interlayer links are sufficient for an optimal propagation of weak signals to great depths of the feedforward neuronal network, provided the signal frequency and the intensity of intrinsic noise are appropriately adjusted. © 2010 Wolters Kluwer Health | Lippincott Wil . . .liams & Wilkins Daha fazlası Daha az

Uzun, Rukiye | Özer, Mahmut

Proceedings | 2017 | Istanbul University - Journal of Electrical and Electronics Engineering17 , pp.3069 - 3073

In this paper; the effects of autapse (a kind of self-synapse formed between the axon of the soma of a neuron and its own dendrites) and ion channel blockage on the firing regularity of a biological small-world neuronal network, consists of stochastic Hodgkin-Huxley neurons, are studied. In this study, it is assumed that all of the neurons on the network have a chemical autapse and a constant membrane area. Obtained results indicate that there are different effects of channel blockage and parameters of the autapse on the regularity of the network, thus on the temporal coherence of the network. It is found that the firing regularity . . .of the network is decreased with the sodium channel blockage while increased with potassium channel blockage. Besides, it is determined that regularity of the network augments with the conductance of the autapse Daha fazlası Daha az

Özer, Mahmut

Article | 2006 | Physics Letters, Section A: General, Atomic and Solid State Physics354 ( 4 ) , pp.258 - 263

The channel noise that stems from the stochastic nature of the ion channel has important effects on neuronal dynamics. In this context, we investigate the effect of the sub-threshold periodic current forcing on the regularity and synchronization of neuronal spiking activity by using a stochastic extension of the Hodgkin-Huxley model. We demonstrate that the intrinsic coherence resonance is independent of the forcing frequency for very small patch size while it is dependent on the frequency for larger sizes. We also show that the observed phase locking behavior occurs on the positive phase of the periodic current forcing for a small . . .frequency range while the spikes fire most frequently at negative phase as the frequency is increased. © 2006 Elsevier B.V. All rights reserved Daha fazlası Daha az

Özer, Mahmut | Uzuntarla, Muhammet | Perc, Matjaž | Graham, Lyle J.

Article | 2009 | Journal of Theoretical Biology261 ( 1 ) , pp.83 - 92

Özer, Mahmut | Uzuntarla, Muhammet | Ağaoğlu, Şükrüye Nihal

Article | 2006 | Physics Letters, Section A: General, Atomic and Solid State Physics360 ( 1 ) , pp.135 - 140

We first investigate the amplitude effect of the subthreshold periodic forcing on the regularity of the spiking events by using the coefficient of variation of interspike intervals. We show that the resonance effect in the coefficient of variation, which is dependent on the driving frequency for larger membrane patch sizes, disappears when the amplitude of the subthreshold forcing is decreased. Then, we demonstrate that the timings of the spiking events of a noisy and periodically driven neuron concentrate on a specific phase of the stimulus. We also show that increasing the intensity of the noise causes the phase probability densit . . .y of the spiking events to get smaller values, and eliminates differences in the phase locking behavior of the neuron for different patch sizes. © 2006 Elsevier B.V. All rights reserved Daha fazlası Daha az