pdepe does not allow for time derivatives in the boundary conditions. The boundary conditions are expressed in terms of the flux term f(x,t,u,dudx) in the PDE equation, which only includes the spatial derivative.
If you instead had du/dx(0, t) = du/dx(1, t) on the ring, then you could use m = 1 for a spherical geometry. Whenever m > 0 pdepe automatically imposes its own left boundary condition to account for the singularity at the origin, so then you would just need to code the right boundary condition.
