https://doi.org/10.1140/epje/i2009-10476-8
Regular Article
Physical model for the width distribution of axons
Department of Chemical Physics, Weizmann Institute of Science, P.O. Box 26, 71600, Rehovot, Israel
* e-mail: nir.gov@weizmann.ac.il
Received:
29
January
2009
Revised:
21
May
2009
Accepted:
8
June
2009
Published online:
5
July
2009
The distribution of widths of axons was recently investigated, and was found to have a distinct peak at an optimized value. The optimized axon width at the peak may arise from the conflicting demands of minimizing energy consumption and assuring signal transmission reliability. The distribution around this optimized value is found to have a distinct non-Gaussian shape, with an exponential “tail”. We propose here a mechanical model whereby this distribution arises from the interplay between the elastic energy of the membrane surrounding the axon core, the osmotic pressure induced by the neurofilaments inside the axon bulk, and active processes that remodel the microtubules and neurofilaments inside the axon. The axon’s radius of curvature can be determined by the cell’s control of the osmotic pressure difference across the membrane, the membrane tension or by changing the composition of the different components of the membrane. We find that the osmotic pressure, determined by the neurofilaments, seems to be the dominant control parameter.
PACS: 87.16.Mq Morphology of nerve cells – / 87.16.ad Analytical theories – / 87.16.dm Mechanical properties and rheology – / 87.16.Ka Filaments, microtubules, their networks, and supramolecular assemblies –
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2009