Elongation of tau proteins along the MTs, U2(X,T) – U1(X,T), with (a) L/Lc = 0.28 and (b) L/Lc = 1.40 and also axial strain along microtubules, ∂U1(X,T)/∂X, with (c) L/Lc = 0.28 and (d) L/Lc = 1.40, when overall elongation of the axon is 10%. The centers of the MTs stretch more with increasing strain rate and increasing length. To see this figure in color, go online.