Tracks analysis: oscillating movement

Dear Forum,
we are working on a vesicle movement project, where we would like to describe with some parameter the oscillating movement of these particles.

Just to put a little bit of biology, they are moving on neuronal axons so more or less they exhibit a movement on a straight line (the axons), but it seems some of them go back and forward along the axons others they just go in one direction.

So, the question is: do you know some good parameter/plot/model to describe how much a particle has an oscillating movement, without reinventing the wheel?

have a nice day,
Emanuele Martini