title: Parameter-specific modulation of the mismatch negativity to duration decrement and increment: evidence for asymmetric processes.
abstract: OBJECTIVE
  The mismatch negativity (MMN) component of event-related potentials (ERPs) reflects a change-detection process in the brain. The present study investigated whether stimulus parameters (sound type and duration) exert a differential influence on the MMN for a duration decrement and increment of an equal magnitude. Some asymmetries were reported in the previous studies; yet no systematical study has been conducted.
  
  
  METHODS
  ERPs were recorded from 16 healthy adults presented with repetitive standard sounds interspersed with duration changes (deviant sounds). In separate sequences, stimuli were vowels, music chord, sinusoid, or band-pass filtered white noise. The stimulus durations (standard/deviant) were either 200/120 ms or 400/240 ms for decrements, and vice versa for increments.
  
  
  RESULTS
  The MMN for the increments was abolished in the 400/240 ms condition, whereas the MMN for decrements was significant irrespective of the sound duration. The amplitude of the increment MMN paralleled with the spectral complexity of the stimulus sound, whereas that of the decrement MMN was larger for natural sounds than artificial sounds.
  
  
  CONCLUSIONS
  The observed interactions demonstrated asymmetries in the MMN for duration increment and decrement.
  
  
  CONCLUSIONS
  The present findings suggest that the effects of stimulus parameters should be taken into account when comparing different studies, especially where clinical populations are involved, with one another.
authors.affiliation: Cognitive Brain Research Unit, Department of Psychology, PO Box 9, University of Helsinki, Finland and Helsinki Brain Research Centre, Finland. rika.takegata@helsinki.fi
authors.forename: Rika
authors.initials: R
authors.lastname: Takegata
authors.forename: Mari
authors.initials: M
authors.lastname: Tervaniemi
authors.forename: Paavo
authors.initials: P
authors.lastname: Alku
authors.forename: Sari
authors.initials: S
authors.lastname: Ylinen
authors.forename: Risto
authors.initials: R
authors.lastname: Näätänen
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009146:Music / Q000523:psychology; D013060:Speech