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Abstract:
Abstract: NJ, USA Research suggests that ability to detect
rapid sound changes is related to speech perception. Brain event
related potentials (ERPs) to pitch changes in tone pairs with
variable within-pair interstimulus intervals (ISI) were studied
using an oddball paradigm with normal healthy adults. A low-low
complex tone pair (100 Hz-100 Hz, 75 dB SPL) was the standard
stimulus, occasionally replaced by a deviant (100 Hz-300 Hz, 15 %).
In the passive condition participants were reading, whereas in the
active condition participants pressed a button upon detecting the
target stimulus. In both conditions blocks of 300 and 70 ms ISI
were used. Preliminary analyses (7 participants) reveal that in all
conditions ERPs to the standard and deviant stimuli differed,
showing robust pitch discrimination. Interestingly, the stimuli
with 300 ms ISI elicited biphasic response patterns corresponding
to the physical gap duration within the paired stimulus, whereas
those with 70 ms ISI showed a more merged response pattern
suggesting temporal integration. Attention selectively modified the
response for the deviant stimuli. The second negative deflection,
reflecting preattentive change detection (mismatch negativity) and
perhaps attention dependent N2, was larger in the active condition
for the deviant stimulus with 70 ms ISI but not for 300 ms ISI.
This suggests a rate-related attentional modulation of change
detection response.
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