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Abstract:
Abstract: The Mismatch-Negativity (MMN) is a negative
potential formed by taking the difference between event-related
potentials (ERPs) to frequent (standard) and infrequent (deviant)
auditory stimuli. It has been used to determine whether subjects
can discriminate between stimuli that differ by specific physical
features. Furthermore, it has been reported that MMN amplitude can
be used as a measure of the size of the physical and conceptual
distance between two stimuli. Therefore, we employed the MMN to
index categorical perception of linguistic stimuli (phonemes) and
as a measure of the detectability of fast temporal changes in
non-linguistic stimuli including brief gaps in tones and frequency
modulations. ERPs were recorded from 32 channels. Subjects were
asked to watch a silent video during the presentation of phonemes
(/t/ and /d/ with voice-onset times of 10, 30, 50, and 70ms), tones
(500Hz with gaps of 0, 2, 4, and 40ms) and frequency modulated
sounds (over 0, 10, 40, and 200ms). By using both linguistic and
non-linguistic stimuli to elicit MMNs in the same subjects, it was
possible to determine if the neural systems involved in fast
temporal processing of the two types of material were identical or
not. The results to date suggest that although the MMN elicited by
the different types of stimuli were similar across subjects, there
were also some differences between the MMNs to linguistic and
non-linguistic stimuli.
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