Synaptic Noise Facilitates the Emergence of Self-Organized Criticality in the Caenorhabditis elegans Neuronal Network

Avalanches with power-law distributed size parameters have been observed in neuronal networks. This observation might be a manifestation of the self-organized criticality (SOC). Yet, the physiological mechanicsm of this behavior is currently unknown. Describing synaptic noise as transmission failures mainly originating from the probabilistic nature of neurotransmitter release, this study investigates the potential of this noise as a mechanism for driving the functional architecture of the neuronal networks towards SOC. To this end, a simple finite state neuron model, with activity dependent and synapse specific failure probabilities, was built based on the known anatomical connectivity data of the nematode Ceanorhabditis elegans. Beginning from random values, it was observed that synaptic noise levels picked out a set of synapses and consequently an active subnetwork which generates power-law distributed neuronal avalanches. The findings of this study brings up the possibility that synaptic failures might be a component of physiological processes underlying SOC in neuronal networks

Synaptic noise facilitates the emergence of self-organized criticality in the Caenorhabditis elegans neuronal network

Avalanches with power-law distributed size parameters have been observed in neuronal networks. This observation might be a manifestation of self-organized criticality (SOC). Yet, the physiological mechanisms of this behaviour are currently unknown. Describing synaptic noise as transmission failures mainly originating from the probabilistic nature of neurotransmitter release, this study investigates the potential of this noise as a mechanism for driving the functional architecture of the neuronal networks towards SOC. To this end, a simple finite state neuron model, with activity dependent and synapse specific failure probabilities, was built based on the known anatomical connectivity data of the nematode Ceanorhabditis elegans. Beginning from random values, it was observed that synaptic noise levels picked out a set of synapses and consequently an active subnetwork that generates power-law distributed neuronal avalanches. The findings of this study bring up the possibility that synaptic failures might be a component of physiological processes underlying SOC in neuronal networks. © 2018, © 2018 Taylor & Francis

Synchronization Cost of Coupled Oscillators with a Spatial Embedding

Synchronous behavior brings advantages for complex systems. Yet, this advantage comes with a cost: Emergence and sustainability of synchronization requires a continuous exchange among the interacting units. Thus, networks with optimal synchronization dynamics is a subject of active research. In this study, we define a cost function for synchronization which takes into account both the network structure which is embedded in space and the dynamic coupling within the system. Beginning from a fully connected network and using an edge pruning strategy based on simulated annealing, we searched for optimal configurations for synchronization with minimum cost. We observed that the same levels of synchronization with a fully connected network can be reached by different networks with sparse connections. We conclude that the chain structure, clustering behavior and degree-frequency relations are the main determinants of optimally synchronizable network structures. © 2013 IEEE

Kucuk Dunya A?larinda Eşzamanlama Davranişinin Kuramoto Modeliyle Incelenmesi]

27th Signal Processing and Communications Applications Conference, SIU 2019 -- 24 April 2019 through 26 April 2019 -- -- 151073In this study, the synchronization behaviour of coupled oscillators with heterogeneous intrinsic frequencies is investigated with the Kuramoto Model. The network structure is varied between the completely regular and completely random states and the synchronization among the oscillators is determined by quantifying the phase locking among them. It is concluded that the synchronization is optimal in the small world regime which stands between the fully regular and random states. © 2019 IEEE

Minimum Spanning Tree Reflects the Alterations of the Default Mode Network During Alzheimer's Disease

This study analyzes the connectivity pattern of the default mode network (DMN) in patients with Alzheimer's disease (AD) in comparison with young and elderly controls using the minimum spanning tree (MST). This tree is a tool from graph theory and connects all the nodes of a graph with the minimum cost. The findings revealed that the alterations of the basic structure represented by the MST might provide valuable insights about the physiopathology of the disease. Additionally, by making use of the MST for functionally clustering the DMN, it was shown that the functional subnetworks comprising the DMN differed among the three subject groups. Nonetheless, there were intact prefrontal and temporal networks in elderly controls and AD patients, as well. The analysis shows that although the topologies of the MST characterized by the degree distributions do not differ significantly among the groups, the DMN of the AD patients exhibits a higher segregation, insomuch that posterior cingulate/precuneus and hippocampus/parahippocampus are heavily isolated from rest of the network. We conclude that the MST can be used effectively for analyzing cortical networks.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109E202]The author acknowledges the support from the Scientific and Technological Research Council of Turkey (TUBITAK) under grant no. 109E202

Alzheimer hastali?inda beyi?n varsayilan durum a?inin en küçük örten a?aç i?le i?ncelenmesi?]

2011 IEEE 19th Signal Processing and Communications Applications Conference, SIU 2011 -- 20 April 2011 through 22 April 2011 -- Antalya -- 85528This study analyzes the connectivity pattern of the default mode network (DMN) in patients with Alzheimer's disease (AD) in comparison with young and elderly controls using the minimum spanning tree (MST). The findings revealed that the alterations of the basic structure represented by the MST might provide valuable insights about the physiopathology of the disease. Additionally, by making use of the MST for functionally clustering the DMN, it was shown that the functional subnetworks comprising the DMN differed among the three subject groups. Nonetheless, there were intact prefrontal and temporal networks in elderly controls and AD patients, as well. The analysis shows that the DMN of the AD patients exhibit a higher segregation. We conclude that the MST can be used effectively for analyzing cortical networks. © 2011 IEEE

Betonarme çerçeveli yapıların lineer olmayan analizi.

Reinforced concrete frames display nonlinear behavior both due to its composite nature and the material properties of concrete itself. The yielding of the reinforcement, the non-uniform distribution of aggregates and the development of cracks under loading are the main reasons of nonlinearity. The stiffness of a frame element depends on the combination of the modulus of elasticity and the geometric properties of its section - area and the moment of inertia. In practice, the elastic modulus is assumed to be constant throughout the element and the sectional properties are assumed to remain constant under loading. In this study, it is assumed that the material elasticity depends on the reinforcement ratio and its distribution over the section. Also, the cracks developing in the frame element reduces the sectional properties. In case of linear analysis, the material and sectional parameters are assumed to be constant. In practice, the modulus of elasticity E is a predefined value based on previous experiments and the moment of inertia I is assumed to be constant throughout the analysis. However, in this study, E and I are assumed to be combined. In other words, they cannot be separated from each other throughout the analysis. These two parameters are handled as a single parameter as EI . This parameter is controlled by the reinforcement ratio and its configuration, sectional properties and deformation of the member. Two types of analysis, namely a sectional and a finite element analyses, are used in this study. From the sectional analysis, the parameter EI is calculated based on the sectional geometry, material properties and the axial load applied on the section. The parameter EI is then used in the finite element analysis to calculate the sectional forces and the nodal displacements. For the nonlinear analysis, the Newton-Raphson iterative approach is followed until convergence is obtained.M.S. - Master of Scienc

Türkçe P300 heceleti?ci?si? i?çi?n görsel uyaran yerleşi?mi? karşilaştirmasi]

2012 20th Signal Processing and Communications Applications Conference, SIU 2012 -- 18 April 2012 through 20 April 2012 -- Fethiye, Mugla -- 90786A P300 speller is designed, that is implemented with Turkish characters. The designed P300 speller is used as a brain computer interface via electroencephalogram (EEG). For this speller, the visual stimulus has been prepared for two different letter placements. The first of these placements, which is very common in the literature, is the square formed letter sequence. The second placement of letters is designed to consist of a gap on top and at the bottom rows of letters in the form of parallelogram. For the two different letter placements, data are collected from the subjects. The data are evaluated for the placement changes' effects on the designed P300 speller. © 2012 IEEE

Mobile Posturographic Analysis System

Electric Electronics, Computer Science, Biomedical Engineerings' Meeting (EBBT) -- APR 26-27, 2016 -- Istanbul, TURKEYThere is an increasing ratio of balance losses and consequently risk of falling with aging population. The failure of current treatment methods to achieve significant improvements has rendered the patient passive in his/her daily life. Therefore, with the aid of a mobile system which will collect continuous data during subjects' daily lives, this study aims at determining and investigating posture deformity and helping the physicians in forming the training plans of their patients. The device was designed to record the movements of the body on the roll and pitch planes. Depending on age and gender, recorded parameters have been thought to be compared automatically with normal data. A computer interface was designed for the physicians to visualize and inspect the measurements.IEEE, EMB, Istanbul Arel Uni

Modeling cortical states by spiking neurons

22nd IEEE Signal Processing and Communications Applications Conference (SIU) -- APR 23-25, 2014 -- Karadeniz Teknik Univ, Trabzon, TURKEYComputational neuroscience has been effective in providing tools for investigation of cognitive processes along with neurode generative diseases and neurological disorders, recently. In this work, it will be shown that it could be possible to understand the mechanisms behind cortical dynamics using spiking neural networks. Here, Izhikevich neuron model is used to set up a cortex model and with this model, signals related to brain dynamics have been observed.IEEE, Karadeniz Tech Univ, Dept Comp Engn & Elect & Elect Eng