Browsing by Author "Ilola, Marianne"

Objectives: The mismatch negativity (MMN) is a component of event-related potential reflecting a process where violations of regularities in auditory input are detected pre-attentively. In commonly used oddball- paradigm a repetitive standard stimulus is infrequently replaced by a deviant stimulus. Auditory deviance elicits MMN even in the absence of focused attention to stimuli. Automaticity of the MMN process has been an object of controversy due to limitations in methods used in most studies. Object of this study was to examine if potential attentional effects (suppression / enhancement) on MMN are similar or different to auditory stimuli violating regularities either physically or abstractly. Another goal was to examine if commonly used video-watching task can sufficiently keep attention directed away from the stimuli. Methods: Auditory stimuli was presented in an oddball paradigm. In physical stimuli blocks the deviant stimuli were higher in frequency compared to that of the standards. In abstract stimuli blocks the standard stimuli were tone pairs ascending in frequency, and deviant stimuli were descending tone pairs. Direction of attention was modulated by three conditions where subject’s task was to a) play a computer game (Tetris) b) watch a silent movie or c) focus on listening the stimuli and press a button to softer target deviants. Physical and abstract stimuli blocks were presented in each condition. Results: Both physical and abstract deviants elicited significant MMN in all three conditions. Direction of attention modulated by different tasks didn’t have a significant effect on amplitude of MMN elicited by physical and abstract deviants. Attention didn’t have any different effect on MMN regardless if it was elicited by stimuli violating regularities either physically or abstractly. Conclusions: The results of this study support the interpretation of MMN reflecting an automatic, attention- independent process where violations of regularities in auditory input are detected. Watching a silent movie seemed to sufficiently direct attention away from stimuli. Therefore video condition can be used as a primary task in future studies as well. Sometimes using a computer game similar to Tetris can be preferable since it might better uphold the arousal level of the subject.