Before revision:  Given a large number of measurements and corresponding stimuli , we wish to identify the correct " response function " relating R to S . However the "noise function" relating M to R is unknown a priori.
After revision:  Given a large number of measurements and corresponding stimuli , we wish to identify the correct " response function " that maps S to R. However, the standard method for solving such problems, likelihood-based inference, requires perfect a priori knowledge of the "noise function" relating M to R is unknown a priori.