fMRI studies of visual cortical activity during noise stimulation

Psychophysics experiments on the human visual system have established that the sensitivity for the detection of fine detail in noise contaminated imag es can be quantitatively and repeatably measured using stochastic resonance as a tool. Optimal noise results in maximal sensitivity. Does this mean si mply that the retina is averaging out the noise, or instead is the visual c ortex involved in some level of computation? We report results of functiona l magnetic resonance imaging experiments which indicate the latter. (C) 199 9 Elsevier Science B.V. All rights reserved.