Perturbations of the electronic temperature and density produced by Ion Cyclotron Resonance Frequency (ICRF) power modulation in JET are analyzed 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 into the particle balance equation. These results are in close agreement with recent analyses of heat and density pulse propagation following a sawtooth collapse.