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Oades, R.D. & Dittmann-Balcar, A. (1995) Mismatch negativity (MMN) is altered by directing attention. NeuroReport, 6, 1187-1190. (request a copy) . (view) . Introduction: MMN is a negative component resulting from the difference in event-related potential (ERP) waveforms elicited by a standard and a deviant stimulus. It is usually studied in the absence of attentional requirements. Method: Here we compare this measure of perceptual comparison in a nontask situation (3 tones presented) with that obtained in a task requiring focussed attention and response to the third tone. Subjects were 9 male and 16 female healthy volunteers aged 18-25 years Results: MMN
amplitude (comparison of standard and deviant irrelevant
tones) increased with focussed attention to the third (target) tone
and frontal maxima shifted slightly posteriorly. Conclusion: This demonstrates that not only attending to stimuli, but the active processing of irrelevant stimuli (vs passive perception) involves small changes of the amount and distribution of neural activity. i.e. active controlled processing in focussed attention can affect the capacity or distribution of resources even for automatic processing of information (the MMN). See also initial studies of MMN in schizophrenia from 1991 , 1993, 1995, on topographical comparisons with other waveforms 1996, and on the role of attention/subgroup contributions 1997 . Other reports on the expression of 'difference waveforms' in normal adults (1995b) and the normal development of MMN in children and adolescents (1997b) |