Multimode Phenomena in Cellular Processes
O.V. Sosnovtseva, A.N. Pavlov, N.A. Brazhe, A. R. Brazhe, H. Braun, and E. Mosekilde
It is well-known that many cells display complex oscillatory phenomena in their respiratory, metabolic, and electrophysiological processes. Phenomena of this type are revealed both in patch clamp experiments and in fluorscent studies. In general, however, a particular technique only allows the observation of a single or a few modes at a time. Through the application of the newly developed technique of interference microscopy and by analysing the obtained data by means of a double-wavelet approach we have revealed the simultanous presence of 8-9 dynamic or oscillatory processes in isolated (Lymnaea stagnalis) neurons. The technique of interference microscopy provides a time and space resolved measure (the phase height) of the time delay of a light signal through the cell. This time delay reflects the refraction index in the light path and, hence, provides information not only on the position (and dynamics) if intracellular and membrane-bound structures, but also about the variations in the ionic concentrations.
A first wavelet analysis transforms the temporal phase height variation into traces that show the variation of the amplitudes and frequencies of the most pronounced modes. By submitting the signal to a secondary wavelet analysis we can reveal how the modes interact with one another and, particularly, how the slower modes modulate the more high-frequency components.
Some of the observed modes can be identified by reference to previous studies, through separate experiments that show how the modes react to changes in the external conditions, and through an analysis of the modes with which they interact. Ongoing work will provide a more detailed identification of the various modes. We are also trying to examine variations in mode amplitudes and frequencies across the cell surface and to investigate the effects of coupling to neighboring cells.
Our efforts in this field also include modeling of the influence of noise on the spiking and bursting behaviour of nerve cells, of small clusters of interacting nerve cells, and of the interaction between nerve and glia cells. In parallel with this work we have worked on the modeling of pancreatic alpha- and beta-cells and on interacting muscle cells.
For further details see our recent publications.