Perturbations of the electronic temperature and density produced by ion cyclotron resonance frequency (ICRF) power modulation in JET are analysed in terms of coupled transport equations. The incremental heat diffusivity is an order of magnitude larger than the incremental particle diffusivity. Off-diagonal transport plays a significant role by coupling the temperature perturbations to the particle balance equation. These results are in agreement with analyses of heat and density pulse propagation following a sawtooth collapse