Controlling the spontaneous spiking regularity via channel blocking on Newman-Watts networks of Hodgkin-Huxley neurons

We investigate the regularity of spontaneous spiking activity on Newman-Watts small-world networks consisting of biophysically realistic Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise and fraction of blocked voltage-gated sodium and potassium ion channels embedded in neuronal membranes. We show that there exists an optimal fraction of shortcut links between physically distant neurons, as well as an optimal intensity of intrinsic noise, which warrant an optimally ordered spontaneous spiking activity. This doubly coherence resonance-like phenomenon depends significantly, and can be controlled via the fraction of closed sodium and potassium ion channels, whereby the impacts can be understood via the analysis of the firing rate function as well as the deterministic system dynamics. Potential biological implications of our findings for information propagation across neural networks are also discussed.Comment: 6 two-column pages, 5 figures; accepted for publication in Europhysics Letter

Double Inverse Stochastic Resonance with Dynamic Synapses

We investigate the behavior of a model neuron that receives a biophysically-realistic noisy post-synaptic current based on uncorrelated spiking activity from a large number of afferents. We show that, with static synapses, such noise can give rise to inverse stochastic resonance (ISR) as a function of the presynaptic firing rate. We compare this to the case with dynamic synapses that feature short-term synaptic plasticity, and show that the interval of presynaptic firing rate over which ISR exists can be extended or diminished. We consider both short-term depression and facilitation. Interestingly, we find that a double inverse stochastic resonance (DISR), with two distinct wells centered at different presynaptic firing rates, can appear.Comment: 12 pages, 7 figure

Chimera states in hybrid coupled neuron populations

Here we study the emergence of chimera states, a recently reported phenomenon referring to the coexistence of synchronized and unsynchronized dynamical units, in a population of Morris-Lecar neurons which are coupled by both electrical and chemical synapses, constituting a hybrid synaptic architecture, as in actual brain connectivity. This scheme consists of a nonlocal network where the nearest neighbor neurons are coupled by electrical synapses, while the synapses from more distant neurons are of the chemical type. We demonstrate that peculiar dynamical behaviors, including chimera state and traveling wave, exist in such a hybrid coupled neural system, and analyze how the relative abundance of chemical and electrical synapses affects the features of chimera and different synchrony states (i.e. incoherent, traveling wave and coherent) and the regions in the space of relevant parameters for their emergence. Additionally, we show that, when the relative population of chemical synapses increases further, a new intriguing chaotic dynamical behavior appears above the region for chimera states. This is characterized by the coexistence of two distinct synchronized states with different amplitude, and an unsynchronized state, that we denote as a chaotic amplitude chimera. We also discuss about the computational implications of such state. (c) 2020 Elsevier Ltd. All rights reserved.MU acknowledges Bulent Ecevit University Research Foundation, Turkey under Project No. BAP2018-39971044-01. JJT acknowledges the Spanish Ministry for Science and Technology and the "Agencia Espanola de Investigacion, Spain'' (AEI) for financial support under grant FIS2017-84256-P (FEDER funds). AC acknowledges financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) BIDEB-2214/A International Research Fellowship Program, and the hospitality of the Institute Carlos I for Theoretical and Computational Physics at University of Granada

Vibrational resonance in a scale-free network with different coupling schemes

We investigate the phenomenon of vibrational resonance (VR) in neural populations, whereby weak low-frequency signals below the excitability threshold can be detected with the help of additional high-frequency driving. The considered dynamical elements consist of excitable FitzHugh–Nagumo neurons connected by electrical gap junctions and chemical synapses. The VR performance of these populations is studied in unweighted and weighted scale-free networks. We find that although the characteristic network features – coupling strength and average degree – do not dramatically affect the signal detection quality in unweighted electrically coupled neural populations, they have a strong influence on the required energy level of the high-frequency driving force. On the other hand, we observe that unweighted chemically coupled populations exhibit the opposite behavior, and the VR performance is significantly affected by these network features whereas the required energy remains on a comparable level. Furthermore, we show that the observed VR performance for unweighted networks can be either enhanced or worsened by degree-dependent coupling weights depending on the amount of heterogeneity

Temporal discrimination from the interaction between dynamic synapses and intrinsic subthreshold oscillations

The interaction between synaptic and intrinsic dynamics can efficiently shape neuronal input-output relationships in response to temporally structured spike trains. We use a neuron model with subthresh-old oscillations receiving inputs through a synapse with short-term depression and facilitation to show that the combination of intrinsic subthreshold and synaptic dynamics leads to channel-specific nontrivial responses and recognition of specific temporal structures. Our study employs the Generalized Integrate and-Fire (GIF) model, which can be subjected to analytical characterization. We map the temporal structure of spike input trains to the type of spike response, and show how the emergence of nontrivial input- output preferences is modulated by intrinsic and synaptic parameters in a synergistic manner. We demonstrate that these temporal input discrimination properties are robust to noise and to variations in synaptic strength. Furthermore, we also illustrate the presence of these input-output relationships in conductance-based models. Our results suggest a widespread computationally economic and easily tunable mechanism for temporal information discrimination in single neurons. (c) 2020 Elsevier B.V. All rights reserved.This work was supported AEI/FEDER grants FIS2017-84256-P (JJT) and PGC2018-095895-B-I00, DPI2015-65833-P (RL & PV)

School culture in health education institutions: Gulhane Military Medical Academy (GMMA), health noncommissioned officer college example

Bu araştırmanın amacı, Ankara İli Keçiören İlçesi Etlik Semtinde bulunan GATA Sağlık Astsubay Meslek Yüksekokulu (SAMYO) öğrencilerinin ve yeni mezun stajyerlerin okul kültürüne ilişkin algılarını belirlemek olup, bu çalışma metodolojik (yöntemsel) bir araştırmadır. Araştırmanın evrenini 2. sınıfta öğrenim gören 126 öğrenci ve Samsun Sahra Sıhhiye Okulu'nda eğitim gören 97 stajyer astsubay, toplam 223 kişi oluşturmaktadır. Evrenin tamamına ulaşılmaya çalışılmış olup, 122 öğrenci ve 80 stajyer olmak üzere 202 kişiye ulaşılmıştır. Anket yüz yüze görüşme yöntemi ile uygulanmıştır. Ölçeğe katılım oranı %95'dir. Veri kaynağı olarak Erdem ve İşbaşı tarafından geliştirilen 2001 yılında Akdeniz Üniversitesi İktisadi ve İdari Bilimler Fakültesi (İİBF)'nde, daha sonra Özer ve arkadaşları tarafından 2004 yılında Gülhane Askeri Tıp Fakültesi'nde, Yılmaz ve Oğuz tarafından 2005 yılında Ankara Üniversitesi Eğitim Bilimleri Fakültesi'nde, Köksal tarafından 2007 yılında Balıkesir Üniversitesi'nde, Durmuş tarafından ise 2010 yılında Güvercinlik Teknik ve Endüstri Meslek Lisesi'nde uygulanan ölçek kullanılmıştır. Veri toplama aracı olarak, GATA Sağlık Astsubay Meslek Yüksekokulu (SAMYO) Okul Kültürü anketinden faydalanılmıştır. Araştırmada iki hipotez test edilmeye çalışılmıştır. Veriler bilgisayara SPSS 15.0 istatistik paket programı aracılığı ile yüklenmiş ve verilerin çözümlenmesinde, aritmetik ortalama, standart sapma, frekans analizi, faktör analizi, bağımsız gruplarda t testi ve korelasyon analizi kullanılmıştır. İstatistiksel anlamlılık değeri p<0.05 olarak kabul edilmiştir. Öğrenci ve stajyerler arasında ölçek sorularına verilen önermeler değerlendirildiğinde önermelerin 20'sinde gruplar arasında istatistiksel anlamlı farklılık bulunmuştur. Fark bulunan tüm önermelerde öğrencilerin verdiği yanıtlar stajyerlere göre daha olumlu bulunmuştur. Okul kültüründe ele alınan boyutlardan örgütsel yapı/etkinlik boyutunun iletişim/ilişki, sembol ve güç mesafesi boyutlarıyla; iletişim/ilişki boyutunun örgütsel yapı/etkinlik ve sembol boyutlarıyla; sembol boyutunun örgütsel yapı/etkinlik ve iletişim boyutlarıyla zayıf-orta güçte ilişkisi olduğu bulunmuştur. Güç mesafesi boyutunun ise yalnızca örgütsel yapı/etkinlik boyutuyla ilişkisi vardır.The aim of this study is to investigate the perception of school culture of the students and trainees of the GMMA, Health Noncommissioned Officer College (HNOC) which is located in Ankara, Keçiören town, Etlik district. This study is a methodological study. The population of the study performed on a total of 223 persons which is composed of 126 second year students and 97 trainee sergeants at Field Military Health School, Samsun. Whole population was tried to reach. A questionnaire was performed on 122 students and 80 trainees (total 202 persons). The questionnaire was performed via face to face interview method and the scale participation rate was 95%. The scale which is developed by Erdem and İşbaşı was used as the data source. This scale was later used by Akdeniz University Faculty of Economics and Administrative Sciences (2001), Gulhane Military Medical Academy (Ozer et al, 2004), Ankara University, Faculty of Education (Yılmaz and Oğuz, 2005), Balıkesir University (Köksal, 2007), and Güvercinlik Technical and Industrial Vocational High School (Durmuş, 2010). GMMA, Health Noncommissioned Officer College, School Culture Questionnaire was used for data collection. Two hypotheses was tried to test in the study. The data was uploaded to SPSS 15.0 program and analysis of the data was performed with arithmetic mean, standard deviation, frequency analysis, factor analysis. For independent groups, t test and correlation analysis was used. Statistical significance was set at p<0.05. When the suggestions given to questions of scale by the students and trainees are evaluated, a statistical significance was found between groups of 20 of the suggestions. In all statistically significant suggestions, the response of the students was more positive favorable than trainees. In terms of school culture; it is found that organizational structure/activity dimensions was related with communication/relationship, symbols, and power distance dimensions; communication/relationship dimension was related with organizational structure / function and symbol dimensions; symbol dimension was related with organizational structure / activity and communication dimensions and these relations had weak to moderate strength. Power distance dimension was found to be only related to organizational structure / activity dimension

İleri yönlü biyolojik sinir sinir ağlarında bilgi iletimi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Sinir sisteminde bilginin işlenimi farklı nöronal bölgeler tarafından yapılmaktadır. Bu durum, nöronal aktivitenin bir nöron topluluğundan başka bir nöron topluluğuna iletildiğini göstermektedir. Hesaplamalı yaklaşımlar nöronal aktivitenin farklı bilgi işleme birimleri arasındaki propagasyonunun nasıl gerçekleştiğini anlamada etkili araçlar sunmaktadır. Bu bağlamda ileri yönlü sinir ağları modeli sinir sisteminde bilgi iletiminin incelenmesinde basit bir platformdur. Bu çalışma, nöronların biyofiziksel açıdan daha gerçekçi modelleri kullanılarak ileri yönlü ağda nöronal aktivite propagasyonunun daha iyi bir biçimde anlaşılmasını hedeflemektedir. Ağdaki her bir nöron, membran üzerinde gömülü bulunan iyon kanallarının stokastik davranışlarını da içerecek şekilde hücre büyüklüklerine bağlı olarak modellenmiştir. Çalışmada ilk olarak, zayıf periyodik sinyallerin ileri yönlü ağda iletimindeki optimum koşulların belirlenmesi ele alınmıştır. Nöron iç dinamiklerinden kaynaklanan gürültü şiddeti belirli bir seviyenin üzerinde olduğunda, ilk katmana uygulanan zayıf sinyalin sonraki katmanlar tarafından yükseltilerek iletilebildiği tespit edilmiştir. Bunun yanında, sistemdeki gürültü şiddeti ve sinyal frekansı uygun bir biçimde ayarlandığında, katmanlar arasındaki sinaptik bağlantıların olası tüm bağlantı sayısının %4’ ü kadar olmasının etkili bir zayıf sinyal iletimi için yeterli olduğu gösterilmiştir. Çalışmada ayrıca oransal kodlama bağlamında, katmanlarda farklı gürültü rejimleri oluşturularak ateşleme oranlarının ileri yönlü ağdaki propagasyonu araştırılmıştır. Tüm gürültü rejimlerinde, ateşleme oranının ağdaki iletiminin katmanlarda nöronların sergilediği senkronizasyon mekanizması ile gerçekleşebileceği ortaya konmuştur. Sözü edilen mekanizmanın ileri yönlü ağda ortaya çıkabilmesinin giriş katmanı ateşleme oranı seviyesine, ağdaki sinaptik bağlantı yoğunluğuna, sinaptik akım istatistiklerine ve nöron iç dinamiklerinden kaynaklanan gürültü şiddetine bağlı olduğu da gösterilmiştir. Tespit edilen sonuçlar literatürdeki deneysel sonuçlarla tutarlılık göstermekte ve ileri yönlü ağda bilgi işlemenin nasıl gerçekleştiğinin anlaşılmasına katkı sağlamaktadır.Information processing in the nervous system involves multiple stages of neuronal networks, where neuronal activity progress from one sub-population to another. Computational approaches provide useful tools to understand the underlying mechanisms of the activity propagation through multiple processing stages. A feedforward sequence of layers of neurons provides a simple platform for analyzing the propagation of neuronal activity in the nervous system. The present work aims at a better understanding of neuronal activity propagation in Feedforward Networks (FFN) by including a more biophysically realistic model of individual neurons on the network, where the stochastic behavior of voltage-gated ion channels embedded in neuronal membranes is modeled depending on the cell size. First, it is determined under which conditions the propagation of weak periodic signals through a FFN is optimal. It is found 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, as low as 4% of all possible interlayer links are sufficient for an optimal propagation of weak signals to great depths of the FFN, provided the signal frequency and the intensity of intrinsic noise are appropriately adjusted. Next, in the context of rate coding, firing rate propagation is studied in FFN by considering the different noise regimes in layers. For all regimes, the stable propagation of input firing rate through the network can be achieved via the synchronization mechanism within the neurons in layers. It is also shown that the development of this mechanism in the network depends on the input rate, interlayerlink density, synaptic current statistics and intrinsic noise intensity in layers. Achieved results are consistent with experimental results, given in the literature, and advance our understanding of how information is processed in FFN

Analysis of hemodialysis patients&#146; thoughts about kidney transplantation and the national organ transplant system in terms of organ transplantation services management

Introduction: Kidney transplantation is the most effective treatment of end-stage renal failure. Although many patients continue to wait for a kidney transplant, there are constraints in organ supply. This situation needs to be analyzed and to be managed effectively. Objective: The objective of this study was to determine the status of information regarding kidney transplants provided to patients treated with hemodialysis, the patients&#146; thoughts regarding kidney transplants and the national organ transplant system as well as assessing their registration status at transplant centers. Methods: 273 patients receiving hemodialysis treatment at 4 private dialysis centers in Ankara/Turkey were evaluated within the scope of this descriptive study. The data were collected through a survey method. The survey consisted of 18 questions in total which had been developed by the authors. Results: It was determined that the hemodialysis patients responding to the survey were in the 20-95 age group with an average age of 58,64&plusmn;15,64 years. 87,9% of the patients reported that they had been briefed about kidney transplants, 32,2% of those had been briefed said that the information had been delivered by the dialysis physician, 77,7% stated that they wanted a kidney transplant from a cadaver, 49,5% did not want a kidney transplant from a live donor and 35,5% indicated that the national organ transplant system operated adequately. Furthermore, it was noted that 50,9% of the responders were registered on the waiting lists of kidney transplant centers. Conclusions: It was concluded that it is necessary to provide sufficient information to hemodialysis patients about kidney transplants and the national organ transplant system to steer them to transplant centers. It is anticipated that the results of this study will assist officers of the Ministry of Health, politicians involved in health issues, decision makers and health professionals. [Arch Clin Exp Surg 2017; 6(1.000): 33-37