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Makine öğrenmesi ve özellikle derin öğrenme konularındaki son gelişmeler, tıbbı görüntülerdeki nesneleri tanımaya ve sınıflandırmaya yardımcı olmaktadır. Bu çalışmada endoskopi görüntüleri incelenmiş, normal ve polipli görüntülerin tespit edilerek sınıflandırılması için derin öğrenme yöntemi kullanılmıştır. Önerilen sistem için Kütahya Sağlık Bilimleri Üniversitesi Genel Cerrahi Anabilim Dalı, Evliya Çelebi Eğitim ve Araştırma Hastanesi Genel Cerrahi Endoskopi Ünitesi arşiv görüntüleri kullanılarak normal ve poliplerin olduğu görüntüler alınarak veri tabanı oluşturuldu. Oluşturulan veri tabanında 54 arşiv kaydından alınan, 93 polipli ve 216 normal görüntü bulunmaktadır. Bu verilerden rastgele olarak seçilen verilerin 2/3 ü modelin eğitim için ayrılırken, 1/3 ü modelin test için ayrılmıştır. Bu tez çalışmasında, derin öğrenmedeki en iyi sınıflandırma modelini bulmak için farklı aktivasyon ve optimizasyon fonksiyonları kullanılarak 48 farklı model oluşturulmuştur. Elde edilen verilere göre; modellerin sonuçlarının parametrelere göre farklılık gösterdiği, en iyi modelin gizli katmanında 32 nöron, aktivasyon fonksiyonu ReLU ve optimizasyon yönteminin Adagrad olduğu durumda elde edildiği tespit edilmiştir (%98). Bunun aksine, en kötü modelin gizli katmanında 32 nöron, aktivasyon fonksiyonu ReLU ve optimizasyon fonksiyonu SGD olduğu durumda gözlenmiştir (%69). Sonuç olarak, farklı aktivasyon ve optimizasyon yöntemleri kullanılarak derin öğrenme ile polip görüntü verilerinin başarılı sınıf tahmini yapan bir sistem tasarımı yapılabilir Recent advances in machine learning, particularly with regard to deep learning, help to recognize and classify objects in medical images. In this study, endoscopy images were examined and deep learning method was used to classify healthy and polyp cells. For the proposed system, a database was created from the archives of Kutahya Health Sciences University General Surgery Department Endoscopy Unite in Kutahya Evliya Celebi Training and Research Hospital. The database contains 93 polyps and 216 normal images from 54 archive records. Of these data, 2/3 of the randomly selected data is reserved for the model's training, while 1/3 of the data is reserved for the test. In this study, 48 different models were created by using different activation and optimization functions to find the best classification model in deep learning. According to the experimental results; It was determined that accuracy results of the models depend on the selected parameters. We observed the highest accuracy results by means of 32 neurons in the hidden layer, whereas ReLU activation function and Adagrad optimization method are utilized during the best model with the accuracy rate of 98%. In contrast, when we designed a second model with 32 neurons, utilizing ReLU activation and SGD optimization functions, the accuracy rate reduced to 69%. In summary, classification performance of polyp images can be optimized by utilizing different activation and optimization methods during the design of deep learning models

15. “International Congress of Histochemistry and Cytochemistry” kongresinde poster bildiri olarak sunulmuştur (18-21 Mayıs 2017, Antalya). Nesfatin-1 besin alımını baskılayan, oreksin A ise tetikleyen birbirine zıt etkili iki peptidtir. Bu peptidler hipotalamusta yerleşik olan nöron grupları tarafından sentezlenmekte ve salıverilmektedir. Çalışmamız kapsamında, besin alımının düzenlenmesinde rol oynayan bu iki önemli peptiderjik sistemin birbirleri üzerindeki olası etkileşimi immünohistokimyasal yöntemlerle araştırılmıştır. Bu amaca yönelik olarak, ilgili peptidlerin deneklere verilmesi sonucu diğer peptidi sentezleyen nöronlardaki aktivasyon değişiklikleri incelenmiştir. Bir transkripsiyon faktörü olan c-Fos proteininin yanı sıra, iki farklı hücre içi yolağın aktivasyon belirteci olan fosforile STAT5 (sinyal çevrimcileri ve transkripsiyon aktivatörleri) ve fosforile CREB (c-AMP-yanıtlı element bağlayıcı protein, p-CREB) immün reaktivitesinin varlığı, nöronal aktivasyonun belirlenmesinde kullanılmıştır. Çalışmalarda hipotalamusun supraoptik çekirdeklerinde lokalize nesfatin nöronları ile lateral hipotalamusta lokalize oreksin A nöronları incelenmiştir. Çalışmaların sonucunda nesfatin-1 nöronlarına ait aksonların, oreksin A nöronları üzerinde sinaps oluşturabileceğini düşündürecek şekilde sonlanmalar yaptığı görülmüştür. Ancak nesfatin-1 verilen deneklerin oreksin A nöronlarında c-Fos, pCREB veya pSTAT5 proteinlerinin ekspresyonunda bir değişiklik görülmemiştir. Benzer şekilde oreksin A verilen deneklere ait nesfatin-1 nöronlarında da bu belirteçleri içeren yolaklara ait bir aktivasyon gözlenmemiştir. Sonuç olarak, nesfatin-1 nöronlarının oreksin A nöronlarıyla sinaps oluşturabileceği, nesfatin-1 ve oreksin A peptidlerinin birbiri üzerinde, c-Fos, CREB ve STAT proteinlerinin rol aldığı hücre içi yolakları kullanarak aktive edici etkilerinin olmadığı, ancak her iki peptidi eksprese eden nöronlarda, bu yolakların kullanımıyla farklı moleküllerin besin alımının kontrolü doğrultusunda düzenleyici etki gösterebilecekleri düşünülmüştür. Nesfatin-1 and orexin A are oppositely acting two peptides, while nesfatin-1 suppresses food intake, orexin A stimulates this function. These peptides are synthesized and secreted by neuron groups located in the hypothalamus. In this study, the possible interactions between these two important peptidergic systems that play a role in the regulation of food intake were investigated by using immunohistochemical methods. As a result of the administration of the related peptides to the animals, the activational changes in the neurons synthesizing the other peptides were investigated. In addition to the c-Fos protein which is a transcription factor, we used different cellular signal pathway activation markers such as phosphorylated STAT5 (signal transducers and transcription activators) as well as p-CREB (c-AMP-responsive element binding protein). In these studies, the nesfatin neurons that are localized in the hypothalamic supraoptic nuclei and orexin neurons that are localized in the lateral hypothalamus were examined. The results showed that the nesfatin-1 axons are found to be juxta-positioned on the orexin neurons in order to form a possible synapse. However expression pattern of the c-Fos, pCREB or pSTAT5 proteins in the orexin A neurons showed no difference following the nesfatin-1 injections. Similarly no activation was assessed in the nesfatin-1 neurons after orexin administration. In conclusion, it is suggested that the nesfatin-1 neurons may form synaptic interactions with orexin A neurons, these two neurons cannot activate each other through c-Fos, CREB or STAT proteins, however other molecules may use these pathways in order to regulate these neurons as well as the food intake mechanism.

Bu tez çalışması kapsamında Kayseri İleri Biyolojik Atık Su Arıtma Tesisinde bulunan Çürütücü Ünitesinde üretilen biyogazın gelecek günlerdeki üretim miktarı tahmin edilmeye çalışılmıştır. 1 Nisan 2017 ile 11 Nisan 2019 tarihleri arasındaki biyogaz üretim miktarı verileri kullanılarak MATLAB yazılım programında NARNET modeli ile yapay sinir ağları oluşturulmuştur. NARNET modelinde nöron ve gecikme (delay) sayıları değiştirilerek çok sayıda ağ oluşturulmuş, eğitilmiş ve farklı çalışma bölgelerinde başarı ölçütünü geçen 22 adet ağ kaydedilmiştir. Bu ağlara gelecek günlerdeki biyogaz üretim miktarı tahminleri yaptırılarak gerçek değerlerle karşılaştırılmıştır. Tez kapsamında başarılı ağların oluşturulmuş ve eğitilmiş olması biyogaz üretim miktarı ile ilgili tesiste yapılacak iş ve işlemlerde planlama yapılabilmesini sağlayacaktır., In this thesis, the amount of biogas production in the Digestive Unit in Kayseri Advanced Biological Waste Water Treatment Plant is predicted for the following days using previous data. Artificial neural networks are created with NARNET model in MATLAB software program using biogas production amount data between April 1, 2017 and April 11, 2019. In the NARNET model, many networks are created by changing the number of neurons and delays, and totally 22 networks satisfying the success criteria are recorded. Using these networks the biogas production amounts are estimated for the following days and compared with the actual values. The establishment of successful networks within the scope of this thesis will enable the planning of the work and operations to be performed in the facility related to the amount of biogas production.

Amaç: Nörotrofin ailesinin önemli üyelerinden NT3 ve NT4/5’in, mikroskop kontrollü lazer mikrodiseksiyon tekniğiyle akson kesisi (aksotomi) oluşturulmuş dorsal kök gangliyon (DRG) nöronlarının hayatta kalma kabiliyetini etkileyip etkilemediğini araştırmak. Gereç ve Yöntem: Çalışmada 6-12 haftalık Balb/C ırkı fareler kullanıldı. Aseptik koşullarda DRG’ler çıkartıldı, primer DRG nöron kültürü hazırlandı. Hücre ekiminden 48 saat sonra kültürler, NT3 (50 ng/ml), NT4/5 (50 ng/ml)ve NT3-NT4/5 kombinasyonu ile muamele edildi. Nöritler gövdeden 200 µm uzaklıkta laser mikrodiseksiyon mikroskop sisteminde lazer ışını ile aksotomi edildi. Nöronların ölü-canlı ayrımı için propidyum iyodür (PI) alım testi uygulandı. Nöronlar zaman aralıklı floresan mikroskobik görüntüleme sistemi ile görüntülendi.Bulgular: PI, ölü hücrelerin çekirdeğini floresan mikroskobu altında parlak kırmızı gösterdi. Tüm deney grupları,kontrol grubuna göre 24.ve 48. saatlerde aksotomi edilen nöronların hayatta kalma oranlarında önemli artış gerçekleştirdi. En fazla hayatta kalma oranının NT3+NT4 grubunda, sonra sırasıyla NT3, NT4 ve kontrol gruplarında olduğu belirlendi. Hayatta kalma oranları 48. saatte 24. saate göre azalma gösterse de bu azalma istatistiksel olarak önemsizdi.Sonuç: NT3-NT4/5 kombinasyonu, NT3 (50 ng/ml)ve NT4/5 (50 ng/ml), in vitroaksotomi hasarı modelinde yaralı DRG nöronlarının hayatta kalma oranlarını artırmaktadır. Bu nörotrofik faktörler periferik sinirlerin mekanik yaralanmalarında terapötik potansiyel taşımaktadır., Objective: To investigate whether of NT3 and NT4/5, important members of the neurotrophin family, affect the survival ability of dorsal root ganglion (DRG) neurons that were created axon injury (axotomy) with a microscope-controlled laser microdissection technique.Materials and Methods:6-12 week BALB/c mice were used in the study. DRGs were harvested from mice under aseptic conditions and deep anesthesia. Primer DRG neuron culture was prepared. Forty-eight hours after cell culture, the cultures were treated with NT3 (50 ng / ml), NT4 / 5 (50 ng / ml) and NT3-NT4/5 combination. Neurites were axotomized at 200 μm distance from the perikaryon with the microscope-controlled laser beam. A propidium iodide (PI) uptake test was performed to determine the dead-alive distinction of neurons. Neurons were visualized with a time-lapse fluorescent microscopic imaging system. Results: PI show the dead cells' nucleus as bright red under the fluorescence microscope. All experimental groups showed a significant increase in axotomized-neurons’ survival rates at 24th and 48th hours according to the control group. It was determined that the highest survival rate was in NT3 + NT4 group, then NT3, NT4 and control groups respectively. Although the survival rates decreased compared to the 24th hour at the 48th hour, this decrease was statistically insignificant. Conclusion: Combination of NT3-NT4/5, NT3 (50 ng/ml) and NT4/5 (50 ng/ml) increase the survival rate of DRG neurons in vitro axotomy injury model. These neurotrophic factors have therapeutic potential in the mechanical injury of peripheral nerves.

TEZ11103 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2018. Kaynakça (s. 47-51) var. xiv, 53 s. : res. (bzs. rnk.), tablo ; 29 cm. Bu çalışmada, gebelik öncesi strese sahip dişi sıçanların, yavru hipokampüslerinin Dentate Gyrus bölümündeki granülar nöronların morfolojik değişimleri araştırılmıştır. Genç, yetişkin dişi sıçanlar, beklenmedik stres etkenlerine maruz bırakıldıktan sonra iki gruba ayrılırlar. Gruplardan biri travma sonrası hemen çiftleştirilmiş, diğer grup ise travmadan iki hafta sonra çiftleştirilmiştir. Yavrular yetişkin olduktan sonra hipokampüsleri incelenmiş; granülar nöronların, dendrit uzunlukları, dendrit dallanma sayısı ve toplam dendritik spine (çıkıntı) sayısı hesaplanmış; stres ve kontrol gruplarının cinsiyete ve hemisfere göre karşılaştırılması yapılmıştır. Buna göre, dendrit dallanma sayısının dişi ve erkek yavrularda farklı olduğu tespit edilirken; dendrit uzunluğu ve dendritik spine (çıkıntı) sayısında strese dayalı farklılıklar görülmemiştir. Gebelik öncesi stresin dişi yavrularda dendrit dallanma sayısını arttırdığı, erkek yavrularda ise azalttığı kantitatif olarak hesaplanmıştır. Bununla birlikte, hemisferler arasında fark bulunmamıştır. In this study, the morphological changes of the granular neurons in the Dentate Gyrus region of the rat-offspring’s hippocampus which effected by pregestational stress were investigated. Young adult female rats were divided into two groups after exposure to unexpected stress factors. One group was immediately mated after trauma and the other group was mated two weeks after trauma. After the ffspring became adults, their hippocampus’ were examined; dendritic lengths, dendritic complexity and total dendritic spine number of the granular neurons were calculated; stress and control groups were compared according to sex and hemisphere difference. As a result of these, though the dendritic complexity was found different in female and male offspring; there were no stress-based differences on dendritic length and total dendritic spine number. It was quantitatively calculated that the preconceptional stress impact increases dendritic complexity in female offspring and decreases in male offspring. However, there was no difference between the hemispheres.

2018 Medical Technologies National Congress, TIPTEKNO 2018 -- 8 November 2018 through 10 November 2018 -- -- 144203, In this study, A user-friendly, versatile and easily accessible educational software design was done by using NEURON hoc programming in order to investigate the dynamics, biophysical properties of nerve cells and their responses to various stimulation. With the help of interfaces which prepared for users to be assisted visually, it is aimed to be able to easily perform almost any application desired. This software allows users to perform their simulations without the need to write any code. Considering the features given in detail in the study, it has been suggested to use the software in neuroscience education. © 2018 IEEE.

Medical Technologies National Congress (TIPTEKNO) -- OCT 12-14, 2017 -- TRABZON, TURKEY, WOS: 000427649500043, 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., IEEE Turkey Sect

Medical Technologies National Conference (TIPTEKNO) -- OCT 27-29, 2016 -- Antalya, TURKEY, WOS: 000455003600053, 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 vibrational resonance.

21st National Biomedical Engineering Meeting (BIYOMUT) -- NOV 24-DEC 26, 2017 -- Istanbul, TURKEY WOS: 000447671500032 In pharmacological experiments, the effect of ion concentrations on Action potential (AP) and its association with important neurological disorders such as stroke, epilepsy and depression has been investigated. In this paper, Hodgkin-Huxley (HH) and Morris-Lecar (ML) membrane models, which have contributed to the literature of theoretical neural science, have been studied. In the first step, these two models have been simulated individually in Simulink environment using Matlab software. In the second step, the ratio of the amount of extracellular ion to the amount of intracellular ion was expressed as Hd/Hi. Based on Na. and K. as ions, the effect of Hd/Hi ratio change on AP signal was investigated based on HH and ML as a model. In the HH model, it was searched that the Hd/Hi change due to sodium ions influenced the amplitude of AP and the depolarization phase. The change in Hd/Hi ratio due to potassium ion concentrations was found to affect the threshold and hyper-polarization phase of AP. In the ML membrane model, it was observed that the change in Hd/Hi ratio due to intracellular and extracellular Ca+2 and K- ion concentrations affected the formation time of AP, firing time, amplitude and formation phases. HH and ML models showed similarity in the same parameters.

Medical Technologies National Congress (TIPTEKNO) -- OCT 12-14, 2017 -- TRABZON, TURKEY, WOS: 000427649500045, 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 weak signal detection capacity of a Hodgkin-Huxley (H-H) neuron are investigated. In the study, we consider that the H-H neuron has an inhibitory autapse modeled as a chemical synapse. The subthreshold sine wave is injected to the H-H neuron as a weak signal. Obtained results indicate that inhibitory autapse prominently increases the weak signal detection capacity of a H-H neuron when the proper autaptic time delay and autaptic conductance values are choosen., IEEE Turkey Sect

Medical Technologies National Congress (TIPTEKNO) -- OCT 12-14, 2017 -- TRABZON, TURKEY, WOS: 000427649500046, In this paper, the effects of autapse on the first spike latency of the stochastic H-H neuron are examined. In the study, it is considered that H-H neuron has an electrical autapse and by applying a suprathreshold periodic signal to neuron the first spike times has been observed. Obtained results show that the first spike latency of H-H neuron increases prominently in a certain autaptic time delay with the increasing of autaptic conductance. Also, the first spike latency decreases with the increasing of autaptic conductance in a different autaptic time delay interval. In the context of these results, we come to conclusion that the autapse have played important roles on the control of first spike latency of stochastic H-H neurons., IEEE Turkey Sect

25th Signal Processing and Communications Applications Conference (SIU) -- MAY 15-18, 2017 -- Antalya, TURKEY, WOS: 000413813100017, We investigate how firing dynamics of neuron changes with the autpse's coupling strength for different ratio of the blockage of potassium and sodium ion channels embedded in membranes affects, with using a biophysically more realistic Hodgkin-Huxley neuron model. In the study, we assume that neuron has an excitatory chemical autapse. It is found that the neuron dynamics does not change for too small coupling strength whether it increases after a certain coupling strength' value in case of different ion channel blockage case. Besides, it is determined that potassium ion channel blockage has a healing effect whereas sodium ion channel blockage has a destructive effect on the neuron dynamics increasing with the autaptic coupling strength., Turk Telekom, Arcelik A S, Aselsan, ARGENIT, HAVELSAN, NETAS, Adresgezgini, IEEE Turkey Sect, AVCR Informat Technologies, Cisco, i2i Syst, Integrated Syst & Syst Design, ENOVAS, FiGES Engn, MS Spektral, Istanbul Teknik Univ

Medical Technologies National Congress (TIPTEKNO) -- OCT 12-14, 2017 -- TRABZON, TURKEY, WOS: 000427649500079, 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 short-term depression emerges in the cases where static synapses lead to vibrational resonance., IEEE Turkey Sect

24th Signal Processing and Communication Application Conference (SIU) -- MAY 16-19, 2016 -- Zonguldak, TURKEY, WOS: 000391250900535, 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., IEEE, Bulent Ecevit Univ, Dept Elect & Elect Engn, Bulent Ecevit Univ, Dept Biomed Engn, Bulent Ecevit Univ, Dept Comp Engn

In this study, a software is introduced for simulating the electrical properties of passive dendrite based on the cable theory. Dendrites along which the synaptic information is conveyed are the largest component of a neuron in surface area. The Cable theory for dendritic neurons addresses to current-voltage relations in a continuous passive dendritic tree. It is briefly summarized that the cable theory related to passive cables and dendrites, which is a useful approximation and an important reference for excitable cases. The proposed software can be used to construct user-defined dendritic tree model. The user can define the model in detail, display the constructed dendritic tree, and examine the basic electrical properties of the dendritic tree., Bu çalışmada, kablo teoremine dayalı pasif dentrit elektriksel özelliklerinin benzetimi için geliştirilen bir yazılım tanıtılmaktadır. Üzerinden sinaptik bilgi taşınan dentritler, sinir hücresinin yüzey alanı bakımından en büyük bileşenidir. Dentritik nöronlar için kablo teoremi, sürekli pasif dentrit ağaç yapısı içinde akım-gerilim ilişkilerini modellemektedir. Pasif kablo ve dentritlerle ilgili iyi bir yaklaşıklık olan ve uyarılabilir membranlar için önemli bir referans olan kablo teoremi kısaca özetlenmektedir. Önerilen yazılım, kullanıcı tarafından tanımlanan dentrit ağaç yapısını oluşturmak için kullanılabilmektedir. Kullanıcı, yazılımı kullanarak modeli detaylı olarak tanımlayabilmekte, oluşturduğu dentrit ağacını görüntüleyebilmekte ve dentrit ağacının temel elektriksel özelliklerini inceleyebilmektedir.

23nd Signal Processing and Communications Applications Conference (SIU) -- MAY 16-19, 2015 -- Inonu Univ, Malatya, TURKEY, WOS: 000380500900313, In this study, the biophysical factors underlying the irregular spike patterns produced by neurons in the neocortex, whose cause and function are not fully understood yet, are investigated. In the experimental studies in the literature, it has been proposed that neocortical neurons are subject to high background activity. Thereby, the postsynaptic cortical neuron, used in the study, is modeled as a single-compartment neuron which receives random inputs from a large number of excitatory presynaptic neurons. Furthermore, synaptic transmission lines in the model are designed to include the short-term synaptic depression mechanism. In order to examine the regularity of spike trains in postsynaptic neuron having fix and adaptive threshold, the coefficient of variation of interspikes intervals are computed. The obtained results show that short-term synaptic depression and adaptive threshold mechanisms might be candidate mechanisms explaining the irregular firings in cortical neurons., Dept Comp Engn & Elect & Elect Engn, Elect & Elect Engn, Bilkent Univ

22nd IEEE Signal Processing and Communications Applications Conference (SIU) -- APR 23-25, 2014 -- Karadeniz Teknik Univ, Trabzon, TURKEY, WOS: 000356351400477, In this study, the information coding issue in the nervous system is investigated. By using mathematical equations for modeling the dynamics of the basic units of the system, which are neurons, the information processing performance of the neuron populations is systematically studied. As most of studies in the literature investigate the subject by considering neuron populations as homogenous systems, in this study, the populations are considered as heterogeneous in terms of neuronal excitability. The obtained results demonstrate that considering the heterogeneity of the populations provides significant advantages for the processing of neuronal information. It is shown that the neuron population exhibits maximal performance (resonance) for two different levels of network heterogeneity. Moreover, the influences of other biological parameters, forming the whole system, on this double-resonance phenomenon are investigated., IEEE, Karadeniz Tech Univ, Dept Comp Engn & Elect & Elect Engn

IEEE 15th Signal Processing and Communications Applications Conference -- JUN 11-13, 2007 -- Eskisehir, TURKEY, WOS: 000252924600085, Neurons which are the fundamental elements of the nervous system, encode the information about stimulus they received from the external world by sensory system into action potential (spike) sequences before transmitting to the brain. In this study, a neuron population is modeled in mathematical manner and then first spike appearance time in a spike train is examined against changes in the characteristics of the periodic forcing. We also examine the effect of noise which stems from the biophysical structure of neurons and the effect of synaptic coupling which is the consequence of synaptic interaction of neurons with each other in the population to the appearance time of first spikes. The obtained results show that the mean response time of the population decreases with the increasing frequency. When the intensity of inherent noise in the neuronal environment increased, it shows a decreasing effect on the mean response only for low frequency range of the stimulus. Although the synaptic interaction coefficient does not affect substantially the mean response time of the population, it was shown that it is the fundamental parameter controlling the standard deviation of the response time., IEEE

Bu çalışmada, tavşan pars thoracica trunci sympathici ganglionların ın nöron miktarları ve simpatik zincirin bu parçasının preganglioner lif miktarları araştırıldı. Ganglion sayısı 9-13 arasındadır. Birinci ganglion en çok nörona sahip ganglion dur (1503- 11091). Göğüs simpatik zinciri boyunca preganglioner lif sayısı 5-40 arasında değişmektedir. In this study, neurons in the thoracic sympathetic ganglia and preganglionic fibres of the thoracic sympathetic trunk were counted in rab bit. The ganglia of the thoracic sympathetic trunk were 9-13 in number. The first ganglion has more neurons than other ganglia. The number of its neurons varied from 1503 to 11091. Throughout the thoracic part of the sympathetic trunk, the number of preganglionic fibres also varied from 5 to 40.