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Abstract:
Humans can rapidly adapt motor responses to changes in the
frequency of rhythmic auditory stimuli. The adaptation is rapid
even when the frequency changes by less than 5%, a well-documented
threshold below which subjects do not perceive the change. One goal
of our laboratory is to elucidate the neural mechanisms of this
sensorimotor integration. We recorded EEG from subjects performing
a rhythmic auditory tracking task. Subjects screened for normal
hearing and right handedness were instructed to tap as
synchronously as possible with a train of simple pure tones
delivered binaurally. Each trial consisted of several 417
millisecond interstimulus intervals (ISIs) followed by either
several 400 milliseconds ISIs or several 367 milliseconds ISIs. Our
previous results suggest a hemispheric specialization for the
tapping versus a passive control version of the task. In the
present study we investigated the topography of the dissociation
and the associated temporal dynamics. The topographies suggest that
differential widespread cortical networks are recruited depending
upon whether or not the task requires synchronizing a motor
response to a rhythmic auditory stimulus. The results also suggest
that temporally structured sequences of auditory stimuli undergo
substantial pre-attentive cortical processing.
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