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Volga Neuroscience School 2016 Astroglial control of rhythm genesis in the brain
Design of Optoelectronic Interface Between Neuron-Like Generator and Living Neuron
M.A. Mishchenko*, S.A. Gerasimova, A.V. Lebedeva, V.B. Kazantsev
Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia. * Presenting e-mail: mischenko@neuro.nnov.ru
Abstract. Design of electronic interface between living neuron and neuron-like oscillator is one of the most intriguing challenges in modern science and engineering. Such systems would permit to develop a neuroprosthesis for biomedi-cine. Another interesting application is to make a new generation of information processing technologies based on brain computation principles.
Dynamics of electronic neuron oscillator coupled with living neurons via optoelectronic communication channel has been investigated. Such system mimics interaction between synaptically coupled brain neurons where the optical fiber imitates axon. The optoelectronic communication channel consists of light emission diode (LED), optical fiber and photodiode. Electronic neuron modulates the intensity of LED emission into the fiber and the photodiode detects the light and converts optical signal into electrical pulses that stimulates living neurons. We demonstrated experimentally that such connection can provide stimulation of neuronal firing.
Electronic neuron was implemented as pulse signal generator based on the FiteHugh-Nagumo model. This model provides a qualitative description of the main neurons' characteristics including excitable and self-oscillatory dynamics. Different neuron-like signals (single pulse, transients, self-oscillations) can be observed by changing threshold parameter.
Experiment of coupling electronic and living neurons via optoelectronic channel has been carried out. Such unidirectional signal transmission implements the functionality of excitatory synaptic coupling. Different amplitude of stimulation signal was observed by varying the load resistance of amplifier of photodiode signal. Local field potentials from living neurons have been observed by increasing amplitude of stimulation signal.
Acknowledgements
The work was supported by the Federal Target Program "Research and Development in Priority Areas of the Development of the Scientific and Technological Complex of Russia for 2014-2020" of the Ministry of Education and Science of Russia (Project ID RFMEFI57814X0074, Contract no. 14.578.21.0074).
References
1. S. Gerasimova, G. Gelikonov, A. Pisarchick and V. Kazantsev, JCTE, 2015, 60(8), 900-903.
Oscillations in Physiological Adaptation: Limit Cycles, Oscillating Death and Recovery
A. N. Gorban and T. A. Tyukina*
University of Leicester, Leicester, UK. * Presenting e-mail: tt51@le.ac.uk
In 1938, H. Selye [1] introduced the notion of adaptation energy as the universal currency for adaptation. He published "Experimental evidence supporting the conception of adaptation energy": adaptation of an animal to different factors (sequentially) looks like spending of one resource, and the animal dies when this resource is exhausted [2].
We aim to demonstrate that Selye's adaptation energy [1] is the cornerstone of the top-down approach to modelling of non-specific adaptation processes. We analyse Selye's [3] axioms of adaptation energy together with Goldstone's [4] modifications. Goldstone proposed the concept of a constant production or income of AE which may be stored (up to a limit), as a capital reserve of adaptation. It was shown that this concept best explains the clinical and Selye's own laboratory findings.
The models based on Selye's idea of adaptation energy demonstrate that the oscillating remission and oscillating death do not need exogenous reasons. These phenomena have been observed in clinic for a long time (for example, [5]) and now attract attention in mathematical medicine and biology.
OM&P
OM&P
Volga Neuroscience School 2016 Astroglial control of rhythm genesis in the brain
We propose a series of models for interpretation of Selye's axioms. The adaptation models introduced and analyzed in this work utilize the most common phenomenological properties of the adaptation process: homeostasis (adaptive regulation) and price for adaptation (adaptation resource).
We started with the simplest model with two phase variables, the available free resource (AE) r_0 and the resource supplied for the stressor neutralization, r [6]. The model comprises only four processes: degradation of the available resource, degradation of the supplied resource, supply of the resource from the storage r_0 to the allocated resource r, and production of the resource for further storage (r_0). Analysis of this model has shown its impracticality as for such simple system immortality is possible under infinite load (stress). To overcome this drawback we introduced the following modification: AE production should decrease for large noncompensated stressors f - r. The modified system of equations has the form:
ip = f — r.
(2)
where k_d r is the rate of degradation of resource supplied for the stressor neutralization, where k_d is the corresponding rate constant; k_d0 r_0 is the rate of degradation of the stored resource, and k_d0 is the corresponding rate constant, we assume that k_d > k_d0; kr_0 (f - r)h(f - r) is the rate of resource supply for the stressor neutralization, where k is the supply constant, h(f - r) is the Heaviside step function; k_pr (R_0 - r_0) is the resource production rate, where k_pr is the production rate constant; W(- ) is the fitness (individual performance) function, given by:
4> H4>)\ h / _ h(ip)\
^o / A ^o / The connection between individual performance and 'fitness' is discussed in [6].
Selye, Goldstone and other researchers (for example, Garkavi et al. [7]) have acknowledged that there are different levels of the adaptation energy supply, with lower and higher energy spending. As an extension of the model (1) we introduce two storages of AE: resource r_0 (which is always available if it is not empty) and reserve r_rv (which becomes available when the resource becomes too low). The Boolean variable B_(o /c) describes the state of the reserve storage: if B_(o /c)=0 then the reserve storage is closed and if B_(o /c)=1 then the reserve storage is open. Thus the extended model can be described by the following system of equations:
W{iP) = (i--
Analyzing this model we found oscillations of the adaptation system near the border of death. Thus, the phenomena of 'oscillating death' and 'oscillating remission' can be predicted on the basis of the dynamical models of adaptation.
References
1. H. Selye, Nature, 1938, 141 (3577), 926.
2. H. Selye , Am. J. Physiol., 1938, 123, 758-765.
3. J.K. Schkade, and S. Schulte , Lippincott Williams & Wilkins, 2003, 181-221.
4. B. Goldstone, S. Afr. Med. J. , 1952, 26, 88-92, 106-109.
5. E. Gudayol-Ferre, J. Guardia-Olmos, and M. Pero-Cebollero, Psychiatry research, 2015, 226 (1), 103-112.
6. A.N. Gorban, T. A. Tyukina, E.V. Smirnova, and L. I. Pokidysheva, J. of Theor. Biol. 2015, D0I:10.1016/j. jtbi.2015.12.017
7. L.Kh. Garkavi, E.B. Kvakina, and M.A. Ukolova , Rostov University Press, 1979.
