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Cortical activity associated with rhythmic grouping of pitch sequences

Segmentational grouping in music listening refers to the organisation of individual tones
into tone groups that tend to be processed and subsequently recalled as perceptual units
or chunks. Grouping of tones via this process tends to occur at natural breaks in
structure of a tone sequence, so that relatively larger changes in pitch, amplitude or
timing are perceived as boundaries which cue the segmentational grouping process.
Segmentational grouping processes have been examined using behavioural research
techniques; yet neurophysiological processes underlying the grouping process have
received little attention, and are poorly understood. This study aimed to identify brain
regions involved in the segmentational grouping process as cued by rhythmic
information. Participants performed two auditory tasks while brain electrical activity
responses were monitored using Steady-State Probe Topography (SSPT).
Behavioural responses evoked in a task probing individuals' use of lengthened-duration
tones to organise memory for pitch sequences indicated that longer-duration tones were
used as cues to organise working memory representations of the musical patterns.
Examination of dynamic SSPT responses during the encoding phase of a probe
recognition task indicated that greater use of rhythmic cues to organise working
memory representations was associated with activation of a network of left hemisphere
frontal, temporal and parietal regions. During the lengthened tone, activation of left
central and vertex regions and progressive activation of left temporal and
temporoparietal regions were linked with use of the deviant status of the lengthened
tone to update temporal expectations for the sequence. Excitatory responses observed in
left posterior frontal and temporal regions to a tone following the lengthened tone were
proposed to reflect temporal allocation of attention to this point in time, whereas
sustained excitatory activation of left temporal, and temporoparietal regions reflected
the role of these regions in supporting representations of the tone events in working
memory. Finally, late inhibitory responses to the tone following the lengthened tone in
left frontal, temporal, temporoparietal, and parietal regions were linked with the
manipulation and closure of the working memory trace in association with the grouping
process. Together, these findings support the activation of a network of left frontal,
temporal and parietal regions underlying rhythmic grouping of pitch sequences.

Identiferoai:union.ndltd.org:ADTP/216662
Date January 2007
CreatorsHarris, Philip G., n/a
PublisherSwinburne University of Technology.
Source SetsAustraliasian Digital Theses Program
LanguageEnglish
Detected LanguageEnglish
Rightshttp://www.swin.edu.au/), Copyright Philip G. Harris

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