Following impurity injection by Laser Ablation (LA) in JET plasmas, the electron temperature (Te) is observed to drop at a rate that cannot be accounted for by changes in radiated power (ΔPrad). Te starts to drop promptly over a large fraction of the plasma volume which can be explained by a non local change in electron heat diffusivity. The change in diffusivity, Δχce, is generally short lived, lasting a few milliseconds, even if ΔPrad can persist for longer times. No clear relation between ΔPrad and the strength of the prompt plasma response to LA can be observed, but only those events with Prad/Prad>0.5 give rise to detectable Te perturbations. The Δχce value at the LA time (tLA) is found to increase exponentially with tLA in Hot Ion H mode plasmas reaching values that are much larger than typical Ohmic and H mode levels (for which Δχce ≈ 1 m2/s). The Δχce profile is strongly non uniform in Hot Ion H mode plasmas; moreover, also examples of non monotonic Δχce profiles are found in low power plasmas. Energy transport models combining local and non local (or strongly non linear) features are possible candidates for an explanation of these observations.