  During wound healing, fish keratocyte cells undergo galvanotaxis where they
follow a wound-induced electric field. In addition to their stereotypical
persistent motion, keratocytes can develop circular motion without a field or
oscillate around the field direction. We developed a coarse-grained
phenomenological model that captures these keratocyte behaviors. We fit this
model to experimental data on keratocyte response to an electric field being
turned on. A critical element of our model is a tendency for cells to turn
toward their long axis, arising from a coupling between cell shape and
velocity, which gives rise to oscillatory and circular motion. Galvanotaxis is
influenced not only by the field-dependent responses, but also cell speed and
cell shape relaxation rate. When the cell reacts to an electric field being
turned on, our model predicts that stiff, slow cells react slowly but follow
the signal reliably. Cells that polarize and align to the field at a faster
rate react more quickly and follow the signal more reliably. When cells are
exposed to a field that switches direction rapidly, cells follow the average of
field directions, while if the field is switched more slowly, cells follow a
"staircase" pattern.
