Small changes in temporal deviance modulate mismatch negativity amplitude in humans.

The relative sensitivity of mismatch negativity (MMN) amplitude to small changes in temporal (i.e. timing) deviance of an ongoing stimulus train was investigated. MMN was measured at Fz in response to 3.75-15% decrements of inter-stimulus interval from a 400 ms standard with a deviant probability of 1/15. This parameter space represents the smallest degree of deviance and the narrowest range of variation that has been tested in the context of MMN sensitivity to temporal variables. Waveform amplitude was found to significantly increase with degree of temporal deviance even within this relatively narrow parameter space. This finding is consistent with the view that the MMN corresponds to pre-attentive neural activity that subsequently allows the conscious perception of time during temporal discrimination tasks.