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Abstract:
Abstract: There is growing interest in the role of temporal
patterns of neural activity in auditory processing, yet little
information exists on large-scale temporal patterns of brain
activity during the perception of auditory sequences. To determine
if differences in tone sequence structure are reflected in
measurable, dynamic neural responses, subjects were presented with
long (1-minute) pure tone sequences while neural signals were
recorded using 148-channel whole-head magnetoencephalography (MEG).
Sequences ranged from random to deterministic in statistical
structure. Amplitude-modulation of the tone sequences was used to
generate an ongoing, identifiable neural response whose amplitude
and timing (phase) could be studied as a function of sequence
structure. Temporal patterns of neural activity over particular
brain regions tracked the pitch contour of tone sequences, with the
accuracy of tracking increasing as tone sequences became more
deterministic in structure. In contrast, long-distance temporal
synchronization between recording locations, particularly between
sites over the left posterior hemisphere and the rest of the brain,
was greatest when sequences had melody-like statistical properties.
This may reflect the perceptual integration of pitch patterns at
short and long time-scales in melody-like sequences, i.e. a dynamic
neural signature of perceptual integration of local and global
auditory structure. Temporal aspects of human cortical activity
thus reflect both the structure of tone sequences and the dynamic
brain interactions engendered by these sequences. This work was
supported by Neurosciences Research Foundation.
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