Cytoskeletal heavy tails

The eukaryotic cell's cytoskeleton is a prototypical example of an active material, with objects embedded within it driven by force dipoles exerted by molecular motors. Experiments tracking the behavior of cell-attached objects have observed anomalous diffusion with a distribution of displacements that is non-Gaussian, with heavy tails. This has been attributed to "cytoquakes" or other spatially extended collective effects. We present a simple model that naturally creates heavy power-law tails in cytoskeletal displacements. We predict that this power law exponent should depend on the geometry of where active motors are distributed through the cell, but is likely not strongly dependent on the rheology of the cytoskeleton. We then discuss potential tests of this model both in cells and in synthetic active gels.