New understanding of principles behind computations in the brain

Sep 24 2007

A University of Leicester mathematician has been working with scientists in Japan and The Netherlands to develop a new technique that produces accurate mathematical models of the actual behaviour of nerve (neural) cells.

Developing such models requires detailed information about the dynamics of components responsible for the spike generation in the cell. The main barrier between mathematical modelling and reality is that the most of intrinsic variables of living cell are not available for direct observation. Dr Ivan Tyukin and his colleagues developed a method for automatic reconstructing of hidden variables describing the cell dynamics using only the recordings of evoked electric activity of the cell.

The work of Dr Ivan Tyukin and his colleagues means an advance in the understanding of principles behind computations in the biological brain. It also explores alternative ways to manipulate and enhance the brain function.

Automatic ‘copying’ of simulated neurons into artificial circuits (and potentially in micro-chips) provides electronic and behaviourally almost identical copies of living neurons, and creates new interfaces between biological tissue and mechanical systems.

Dr Tyukin commented: “The developed technique will enable the creation of novel brain-machine interfaces. The artificial neurons can be easily connected with the machines electronically. On the other hand, being sufficiently close copies of their biological counterparts, they can communicate with the biological cells.

Moreover, detecting and tracking instantaneous changes of the internal variables responsible for spike generation in the cells as a function of external chemical stimulation will allow the development of mathematical techniques for the systematic studying of extrasynaptic singalling, which accounts to up to 75 percent of communications among the neurons in some areas of the brain.”

Synaptic transmission is a form of point-to-point communication between neurons which traditionally believed to be the principal mechanism for information processing in the brain. However, recent studies have pointed to importance of extrasynaptic action of chemical transmitters that may provide an additional way how signals may be transferred and transformed.

Dr Tyukin explained: “Understanding and proper mathematical modelling of this phenomenon will allow us to further progress in understanding the physical principles behind computations in the biological brain.

Furthermore, detailed knowledge of how the brain function would change if we modify parameters of diffusion (e.g. changing extracellular volume or adding some large molecules into it) will enable an extra degree of controlling the brain. This is potentially relevant for medical purposes, for instance when we would like to “shield” the focus of stroke by diffusion barrier”

As well as Dr Ivan Tyukin, of the Department of Mathematics at the University of Leicester (UK), the project involves Prof. Cees van Leeuwen, Prof. Alexey Semyanov and Dr Inseon Song from RIKEN Brain Science Institute (Japan) who provide neurophysiological expertise and neuronal activity recordings; Professor Henk Nijmeijer and Mr. Erik Steur from Eindhoven University of Technology (the Netherlands) who are working on an electromechanical realization of the models and are involved in studying of their synchrony.