26 research outputs found
Angiogenic Inhibition Therapy, a Sliding Mode Control Adventure
No full textDoruk, Ozgur/0000-0002-9217-0845[No Abstract Available
Control of Hopf Bifurcations in Hodgkin-Huxley Neurons by Automatic Temperature Manipulation
No full textDoruk, Ozgur/0000-0002-9217-0845The purpose of this research is to revisit the bifurcation control problem in Hodgkin-Huxley neurons. As a difference from the classical membrane potential feedback to manipulate the external current injection, we will actuate the temperature of the neural environment to control the bifurcations. In order to achieve this a linear feedback from the membrane potential is established to generate a time varying temperature profile. The considered bifurcating parameter is the external current injection. Upon finishing the controllers, the bifurcation analysis against the changes in external current injection is repeated in order to see the possibility of relapse of any bifurcation phenomena at nearby points. In addition to that, simulations are also provided to show the performances of the controllers
Neuron Modeling: Estimating the Parameters of a Neuron Model From Neural Spiking Data
No full textDoruk, Ozgur/0000-0002-9217-0845We present a modeling study aiming at the estimation of the parameters of a single neuron model from neural spiking data. The model receives a stimulus as input and provides the firing rate of the neuron as output. The neural spiking data will be obtained from point process simulation. The resultant data will be used in parameter estimation based on the inhomogeneous Poisson maximum likelihood method. The model will be stimulated by various forms of stimuli, which are modeled by a Fourier series (FS), exponential functions, and radial basis functions (RBFs). Tabulated results presenting cases with different sample sizes (# of repeated trials), stimulus component sizes (FS and RBF), amplitudes, and frequency ranges (FS) will be presented to validate the approach and provide a means of comparison. The results showed that regardless of the stimulus type, the most effective parameter on the estimation performance appears to be the sample size. In addition, the lowest variance of the estimates is obtained when a Fourier series stimulus is applied in the estimation
Estimating the Parameters of Fitzhugh-Nagumo Neurons From Neural Spiking Data
No full textDoruk, Ozgur/0000-0002-9217-0845A theoretical and computational study on the estimation of the parameters of a single Fitzhugh-Nagumo model is presented. The difference of this work from a conventional system identification is that the measured data only consist of discrete and noisy neural spiking (spike times) data, which contain no amplitude information. The goal can be achieved by applying a maximum likelihood estimation approach where the likelihood function is derived from point process statistics. The firing rate of the neuron was assumed as a nonlinear map (logistic sigmoid) relating it to the membrane potential variable. The stimulus data were generated by a phased cosine Fourier series having fixed amplitude and frequency but a randomly shot phase (shot at each repeated trial). Various values of amplitude, stimulus component size, and sample size were applied to examine the effect of stimulus to the identification process. Results are presented in tabular and graphical forms, which also include statistical analysis (mean and standard deviation of the estimates). We also tested our model using realistic data from a previous research (H1 neurons of blowflies) and found that the estimates have a tendency to converge
Washout filter based control for the Hodgkin-Huxley nerve cell dynamics
No full textIn this work we present a washout filler based control approach for stabilizing the oscillations in Hodgkin-Huxley type neurons. The oscillations occur due to the bifurcations that arise from the potassium and sodium channel conductance deviations. The MATCONT toolbox software environment was used for analysis of the bifurcation points in conjunction with MATLAB. The simulations of the Hodgkin-Huxley (HH) model at those points are provided to validate the results obtained from, the MATCONT software. Then a washout filter is proposed to stabilize the oscillations occur at the Hopf bifurcation points where the external current injection is used to provide the control actuation. A second simulation set is provided to demonstrate the action of the washout filter
Estimating the Parameters of Fitzhugh–Nagumo Neurons from Neural Spiking Data
No full textA theoretical and computational study on the estimation of the parameters of a single Fitzhugh–Nagumo model is presented. The difference of this work from a conventional system identification is that the measured data only consist of discrete and noisy neural spiking (spike times) data, which contain no amplitude information. The goal can be achieved by applying a maximum likelihood estimation approach where the likelihood function is derived from point process statistics. The firing rate of the neuron was assumed as a nonlinear map (logistic sigmoid) relating it to the membrane potential variable. The stimulus data were generated by a phased cosine Fourier series having fixed amplitude and frequency but a randomly shot phase (shot at each repeated trial). Various values of amplitude, stimulus component size, and sample size were applied to examine the effect of stimulus to the identification process. Results are presented in tabular and graphical forms, which also include statistical analysis (mean and standard deviation of the estimates). We also tested our model using realistic data from a previous research (H1 neurons of blowflies) and found that the estimates have a tendency to converge
Satellite attitude control by integrator back-stepping with internal stabilization
No full textPurpose - This paper aims to focus on the implementation of the integral back-stepping control on the model of BILSAT - 1 satellite of the Turkish Scientific and Technological Research Council (TUBITAK)
Discrete fractional solutions of the radial equation of the fractional Schrödinger equation
No full textParticular solutions of the radial Schrödinger equation via Nabla discrete fractional calculus operator
No full text
