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Memory and information processing in assemblies of neurons

Final Report Summary - MIPAN (Memory and information processing in assemblies of neurons)

The main objective of the project was the study of memory and information processing in assemblies of neurons. Two lines were proposed, one experimental and one theoretical. The experimental research concerned the study of the electrical activity in the cells of plants, situated in the roots, as well as in physical systems reproducing dynamical aspects of biological cells. The realisation of the experiments on plants took place on ground experiments and during the parabolic flights in Bordeaux, France. During the flights the micro (0 g) and macro (2 g) gravity periods were created allowing to gather experimental data with the use of microelectrode array (MEA) device. MEA was previously prepared on the specially constructed rack structure. During analysis of these data, the special attention was put on the changing gravity and chemical substances effects on the cells' electrical activity. The description of the realised project can be found on the European Space Agency (ESA) webpage: http://eea.spaceflight.esa.int/?pg=exprec&id=9135&t=2548894488. The interview with Prof. S. Mancuso (University of Florence, Italy) that collabourated on this project and the researcher working with MEA during parabolic flight (in the microgravity) can be seen here: http://eea.spaceflight.esa.int/attachments/parabolicflights/ID4bd6bb87f0916.mov.

The study of electric activity in plant cells revealed the existence of excitable propagating waves, the dynamics similar to that occurring in animal cells. On the other side, the collabouration with physicists and engineers resulted with many publications [1] on the experimental study of artificial neural networks composed with light emitting diodes as well as designed with use of electronic circuits. This work enabled the experimental simulation of neural dynamics in networks and gave an insight to the understanding of neural interaction and communication. In particular, light emitting diodes (LEDs) were considered, since their use has a potential technological application - they allow to construct miniaturised neural networks on chip. The systems were designed in a way to reproduce neural dynamics, including different dynamical regimes, starting from excitability ending on autonomous chaotic spiking.

Theoretical studies concerning neural networks were based on the derivation of supporting mathematical models, allowing to understand dynamical mechanisms governing such a complex dynamics. Theoretical studies concerning the processing of the information by neurons was considered in the model for rebound bursting obtained by a modification of the Morris-Lecar equations. The main question was how the neurons respond to external stimuli in the presence of thermal (or of another kind) fluctuations. The answer given by the research was that such a response may be highly nonlinear and thus extremely difficult to interpret. The results may be very useful for experimentalists (including plant biologists), who are studying neural systems in vivo as well as in vitro. The results were published in Physica A [2]. The short description of this work can be found on the following webpage: http://www.scitopics.com/Noise_amplified_incoherence_in_bursting.html.

The additional theoretical research was carried out on the assemblies of coupled and autonomously spiking neurons interacting mutually through the spike timing dependent plasticity (STDP) rule, which includes long-term potentiation (LTP) and long-term depotentiation (LTD). The researcher and collaborators, proposed a model for the autonomous transition from sleep to awake and vice-versa by accumulation and loss of information during wake-sleep cycle (published in Chaos [3]).

The researcher spent two weeks at the Department of Biological Physics, Eötvös Loránd University in Budapest, Hungary, under the supervision of Prof. Tamás Vicsek, the famous expert in swarming behaviour of animals. The collabouration concerned the analysis of the experimental data coming from the maize roots and the development of the theoretical models describing the mutual interaction between the roots. The collabouration resulted with a publication in PLoS ONE [4]. The latest research regarded the experimental study of phototactic swimmers that interact in a group and are stimulated by light. The results were published in PLoS ONE [5].

[1] F. Marino, M. Ciszak, S. F. Abdalah, K. Al-Naimee, R. Meucci and F. T. Arecchi, 'Mixed mode oscillations via canard explosions in light-emitting diodes with optoelectronic feedback' Physical Review E 84, 047201 (2011)

[2] M. Ciszak, 'Stochastic incoherence in the response of rebound bursters', Physica A 389, 2351-2357 (2010)

[3] M. Ciszak and M. Bellesi, 'Synaptic plasticity modulates autonomous transitions between waking and sleep states: Insights from a Morris-Lecar model' Chaos 21, 043119 (2011)
Also published as a selected article of frontier research in Virtual Journal of Biological Physics Research Vol. 22, Issue 10 (2011)

[4] M. Ciszak, D. Comparini, B. Mazzolai, F. Baluska, F. T. Arecchi, T. Vicsek, S. Mancuso, 'Swarming behavior in plant roots' PLoS ONE 7(1), e29759-1-e29759-7 (2012)

[5] S. Furlan, D. Comparini, M. Ciszak, L. Beccai, S. Mancuso, B. Mazzolai, 'Origin of polar order in dense suspensions of phototactic micro-swimmers' PLoS ONE 7(6) e38895(1-9) (2012)

More details about the project can be found at the following link: http://www.ino.it/home/marzena/mipan.htm

Contact e-mail:
marzena.ciszak@ino.it.