In this paper we carry out an asymptotic analysis of the proximal-gradient dynamical system
{x˙(t)+x(t)=proxγf[x(t)−γ∇Φ(x(t))−ax(t)−by(t)],y˙(t)+ax(t)+by(t)=0
where f is a proper, convex and lower semicontinuous function, Φ a possibly nonconvex smooth function and γ,a and b are positive real numbers. We show that the generated trajectories approach the set of critical points of f + Φ, here understood as zeros of its limiting subdifferential, under the premise that a regularization of this sum function satisfies the Kurdyka-Łojasiewicz property. We also establish convergence rates for the trajectories, formulated in terms of the Łojasiewicz exponent of the considered regularization function.