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Astrositlerin noron dmamiklenne etkileri fifects of astrocytes on neuronal dynamics

Erkan, Yasemin | Özer, Mahmut | Yılmaz, Ergin

Proceedings | 2017 | 2017 MEDICAL TECHNOLOGIES NATIONAL CONGRESS (TIPTEKNO)

Astrocytes are star-shaped glia cells and the most common cell type in the human brain with neurons. Astrocytes fulfill many functions in human brain. Providing support to the cells of the blood-brain barrier, balancing the extracellular ion concentration, supplying nutrients to the nerve tissue, and controlling the development of nerve cells are some of these tasks. In this study, the effects of calcium (Ca') ion concentration oscillations occuring in astrocytes on the neuron firing dynamics are investigated. When the obtained results are examined, it is observed that the production rate of insole 1,4,5-triphosphate (IP3), which is . . . an agent that triggers calcium release from the resoruces in astrocytes, and the degradation time of that within the cell are important effects on the spike production dynamics of the neuron in contact with astrocyte. It is determined that neurons without any stimulation continue to produce spikes through calcium oscillations in the astrocytes, at high IP3 production rates and longer IP3 degradation times Daha fazlası Daha az

Impact of hybrid autapse on firing regularity in a Hodgkin-Huxley neuron

Yılmaz, Ergin | Baysal, Veli | Özer, Mahmut

Proceedings | 2016 | 2016 24th Signal Processing and Communication Application Conference, SIU 2016 - Proceedings , pp.2233 - 2236

In this paper, the effects of autapse (a kind of synapse formed between the axon or soma of a neuron and its own dendrites) on the firing regularity and the firing rate in single Hodgkin-Huxley neuron are investigated. We consider that Hodgkin-Huxley neuron has two autapses. It is supposed that one of them is electrical synapse and the other is chemical synapse. Obtained results indicate that autapse with proper parameter values (delay time and autaptic conductance) prominently increases the firing regularity and the firing rate of a Hodgkin-Huxley neuron. © 2016 IEEE.

Effects of synaptic time delay on vibrational resonance in neuronal networks

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

Proceedings | 2017 | 2017 25th Signal Processing and Communications Applications Conference, SIU 2017 , pp.2233 - 2236

In the phenomenon of vibrational resonance, the excitable system is under the influence of two periodic forces: a low-frequency (signal), a high-frequency (carrier). In this study, the effects of synaptic time delay on the vibrational resonance were investigated in two coupled FitzHugh-Nagumo neurons with electrical or chemical coupling. It is seen that, for both types of coupling by appropriate choice of synaptic time delay can be had a curative effect to transmission between two neurons at certain values of synaptic conductivity. © 2017 IEEE.

Simulation of Parkinsonian Globus Pallidus Nuclei with various network motifs

Çalım, Ali | Özer, Mahmut | Uzuntarla, Muhammet

Proceedings | 2017 | 2017 Medical Technologies National Conference, TIPTEKNO 20172017-January , pp.1 - 4

Parkinson's disease is a neurodegenerative disorder that affect human life quite negatively with motor, cognitive and psychiatric way. Recent electrophysiological experiments have shown that Basal Ganglia, spaced in the midbrain, can lead to Parkinsonism. Beta frequency oscillations and irregular burstings are most important symptoms of Parkinson's disease. They appear in Globus Pallidus and Subtalamus nuclei during the disease. In this study, anatomical connection features that may give rise to emergence of burstings are investigated, simulating Globus Pallidus and Subtalamus nuclei numerically. © 2017 IEEE.

Vibrational resonance in a Hodgkin-Huxley neuron

Yılmaz, Ergin | Baysal, Veli | Özer, Mahmut

Proceedings | 2015 | 2015 23rd Signal Processing and Communications Applications Conference, SIU 2015 - Proceedings , pp.1114 - 1117

In this paper, the effects of high-frequency driving on the weak signal detection capacity of Hodgkin-Huxley neuron are investigated. It is seen that the response of Hodgkin-Huxley neuron shows vibrational resonance with respect to the amplitude of high-frequency driving, and the best detection is obtained at an optimal amplitude of high-frequency driving. Besides, the effects of the frequency of high-frequency driving on the vibrational resonance are investigated. We arrived at the result that resonant response of the neuron can also be obtained for different frequencies of high-frequency signal but larger amplitudes are required f . . .or greater frequency of high frequency signal. © 2015 IEEE Daha fazlası Daha az

Effects of short term synaptic depression on vibrational resonance in neuronal networks

Çalım, Ali | Özer, Mahmut | Uzuntarla, Muhammet

Proceedings | 2017 | 2017 Medical Technologies National Conference, TIPTEKNO 20172017-January , pp.1 - 4

In this study, vibrational resonance phenomena is investigated in excitable neuron population. Synapses where complex electrochemical events take place in is modelled dynamically, not statically by contrast with early studies. Effect of short-Term synaptic depression which is a prominent feature of dynamic synapses on vibrational resonance is studied. The results of numerical simulations that silencing effect of shortterm depression emerges in the cases where static synapses lead to vibrational resonance. © 2017 IEEE.

Classification of cervical cancer data and the effect of random subspace algorithms on classification performance

Erkaymaz, Okan | Palabaş, Tuğba

Proceedings | 2018 | 26th IEEE Signal Processing and Communications Applications Conference, SIU 2018 , pp.1 - 4

Computer assisted automatic diagnostic systems are used for the purpose of speeding up diagnosis and treatment and helping to make the right decision. In this study, cervical cancer is identified using four basic classifiers: Naive Bayes (NB), k-Nearest Neighbor (kNN), Multilayer Perceptron (MLP) and Decision Trees (KA-C4.5) algorithms and random subspaces ensemble algorithm. Gain Ratio Attribute Evaluation (GRAE) feature extraction algorithm is applied to contribute to classification performance. The classification results obtained with all datasets and reduced datasets are compared with respect to performance criteria such as accu . . .racy, Root Mean Square Error (RMSE), Sensitivity, Specificity performance criteria. According to the obtained performance analysis, it is seen that the classification performance with the random subspace ensemble algorithm using the kNN basic classifier on the reduced data set is the highest (%95.51). © 2018 IEEE Daha fazlası Daha az

Effect of channel noise and dynamic synapse structure on latency dynamics in neural system

Çalım, Ali | Özer, Mahmut | Uzuntarla, Muhammet

Proceedings | 2018 | 26th IEEE Signal Processing and Communications Applications Conference, SIU 2018 , pp.1 - 4

Experimental and theoretical studies in recent years suggest that the first spike latency is an effective information carrier and contains more neural information than other spikes. Noise Delayed Decay (NDD) phenomenon emerges when the first spike latency of the neuron exposed to the periodic driving is maximum at a certain noise intensity interval. In this study, the latency dynamics of a single Hodgkin-Huxley neuron is investigated under periodic driving, background activity through dynamic synapses, and channel noise. The system response with first spike latency is investigated as a function of the presynaptic firing rate, the pa . . .rameter with an appropriate biophysical reality to control the level of activity in the nervous system. First, NDD behavior is investigated under suprathreshold stimulation in the presence of synapses at different levels of depression and channel noise. It is then desired to observe the NDD phenomenon under subthreshold stimulation with the same strategy. Our results have shown that the background activity occurring in the presence of dynamic synapses and the channel noise are significant system dynamics in observing the NDD behavior. © 2018 IEEE Daha fazlası Daha az

Effects of calcium channel noise on weak signal detection in neuron-astrocyte interactions

Erkan, Yasemin | Saraç, Zehra | Yılmaz, Ergin

Proceedings | 2018 | 26th IEEE Signal Processing and Communications Applications Conference, SIU 2018 , pp.1 - 4

In this study, the effects of electrically non-excitable astrocyte cell on the weak signal detection capacity of Hodgkin-Huxley neuron are investigated. To do this, by applying a subthreshold weak signal to neuron, we investigate the weak signal detection capacity of the neuron depending on calcium channel noise stemmed from random open-close fluctuations of calcium channels. Obtained results show that astrocyte decreases the weak signal detection capacity of Hodgkin-Huxley neuron. © 2018 IEEE.

Effects of synaptic heterogenity on vibrational resonance in biological neural networks

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

Proceedings | 2017 | 2016 Medical Technologies National Conference, TIPTEKNO 2016 , pp.1 - 4

In this study, vibrational resonance phenomena is investigated for topologies of scale-free network in excitable neural system. Effect of heterogeneity which emerges from weightening synaptic conductivity in neural network on performance of weak signal detection is studied. FitzHugh-Nagumo neuron model with electrical coupling is used as excitable system. In the result of numerical simulations; it is seen that the state of the scale-free network being unweighted or weighted, synaptic conductivity and average connectivity degree play a crucial role for determining performance of information coding of neuron population based on vibrat . . .ional resonance. © 2016 IEEE Daha fazlası Daha az

Effects of autapse on weak signal detection in FFL network motifs

Baysal, Veli | Yılmaz, Ergin

Proceedings | 2018 | 26th IEEE Signal Processing and Communications Applications Conference, SIU 2018 , pp.1 - 4

In this paper, effects of autapse on signal detection capacity of Izhikevich neuron in feed-forward-loop network motifs are investigated. Obtained results showed that autapse significantly enchances singal detection of Izhikevich neuron at proper autaptic time delay values compared without autapse. Also, it is seen that feed-forward-loop motifs have significant effects on signal detection ability of Izhikevich neuron. It is obtained that signal detection of Izhikevich neuron are best in T1 feed-forward-loop motif. © 2018 IEEE.

Effects of electromagnetic induction on vibrational resonance in single neurons and neuronal networks

Baysal, Veli | Yılmaz, Ergin

Article | 2020 | Physica A: Statistical Mechanics and its Applications537 , pp.1 - 4

In this paper, Vibrational Resonance (VR), in which the response of some dynamical systems to a weak, low frequency signal can be enhanced by the optimal amplitude of high frequency signal, is investigated under the effects of electromagnetic induction in both single neurons and small-world networks. We find that the occurrence of VR in single neurons requires less energy in the presence of electromagnetic induction, although the resonant peak of the response reduces. Besides, VR can be obtained in small-world networks both with and without electromagnetic induction. In small-world neuronal networks, the highest resonance peak of VR . . . enhances with an increase in the probability of adding link in case of without electromagnetic induction. On the other hand, with the increasing of the probability of adding link, VR disappears in the presence of relatively strong electromagnetic induction, while it enhances in the presence of relatively weak electromagnetic induction. © 2019 Elsevier B.V Daha fazlası Daha az

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