Colin, C. 1 , Hoonhorst, I. 1 , Markessis, E. 2 , Collet, G. 1, 3 , Pablos Martin, X. 1 & Deltenre, P. . 1
1 Free University of Brussels (ULB), Belgium
2 Institut Libre Marie Haps, Brussels, Belgium
3 FNRS Belgium
This study was designed to test separately the effect of the featured/featureless nature of deviant stimuli and that of temporal distance between sound and deviance onsets on the Mismatch Negativity (MMN) as well as to look for discrepancies between behavioral discrimination performances and MMN amplitude when deviants are featureless. Ten healthy adults were submitted to stimuli that were contrasted by the presence or absence of a frequency sweep with an onset positioned early or late within the sound. Discrimination performances were collected after the electrophysiological sessions. MMNs were much larger for featured than for featureless deviants. The temporal distance between sound and deviance onset affected featureless deviants strongly, abolishing the MMN when deviance occurred later in the stimulus. Behavioral data were at ceiling levels for all conditions, contrasting with the absence of MMN in the featureless / late onset condition. We propose that two mechanisms contribute to the MMN evoked by featured deviants: the memory comparison process and the adaptation/fresh-afferent one, the former being more sensitive to deviance onset within the Temporal Window of Integration than the latter. These results suggest that the two putative mechanisms of MMN elicitation are not mutually exclusive and can combine to yield composite MMNs.