Simultaneous pitches are encoded separately in auditory cortex: an
MMNm study
Neuroreport, 19 (3):
361--6 (February 2008)DOI: 10.1097/WNR.0b013e3282f51d91
Abstract
This study examined whether two simultaneous pitches have separate
memory representations or an integrated representation in preattentive
auditory memory. Mismatch negativity fields were examined when a
pitch change occurred in either the higher-pitched or the lower-pitched
tone at 25\% probability each, thus making the total deviation rate
of the two-tone dyad 50\%. Clear MMNm was obtained for deviants in
both tones confirming separate memory traces for concurrent tones.
At the same time, deviants to the lower-pitched, but not higher-pitched,
tone within the two-tone dyad elicited a reduced MMNm compared to
when each tone was presented alone, indicating that the representations
of two pitches are not completely independent.