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Abstract:
Abstract: Orangeburg, New York. New York. Bx, New York. The
auditory evoked steady state response (SSR) is driven by rapidly
presented stimuli at rates of approximately 40 Hz and consists of a
superposition of the overlapping transient responses elicited by
each stimulus in the train. Previous studies, using click trains,
have demonstrated that a perturbation of the stimulus train, such
as a change in the amplitude or latency of a click, results in an
amplitude suppression and phase shift in the SSR. This study
employs high-density EEG to examine the perturbation of SSRs driven
by tone pip trains rather than broadband auditory clicks. Using 39
Hz trains of 1000 Hz tone pips we drive the SSR for 1.2 secs.
Perturbing stimuli consisting of tone pips of various frequencies
from 250 Hz to 4000 Hz were introduced midway through the driving
train. The effect of the frequency of these perturbing stimuli on
the amplitude and phase of the SSR driven by 1000 Hz tone pips was
examined. Robust suppression was seen when the perturbing stimulus
was also 1000 Hz. Fall-off of this suppressive effect ensued as the
perturbing frequency deviated from 1000 Hz. This methodology
provides insights into frequency interactions in auditory
cortex.
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