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Abstract:
Is pitch perception mediated through right frontal cortical
regions regardless of the linguistic or non-linguistic context?
This crosslinguistic PET study compares the strategy of pitch
perception in native speakers of English with those of different
tone languages (Thai, Chinese), in which pitch patterns are
linguistically significant
. Subjects (5 per group) were presented binaurally with sound pairs
consisting of monosyllabic Thai words (natural speech) or their
filtered versions (nonspeech). PET scans were acquired using the
bolus H215O methodology in four task condition presented twice:
silent
baseline, pitch, consonant
, and
tone
. Significant focal blood flow changes were identified from
paired-image subtractions of group-averaged data. Behavioral
measures of task performance (e.g., reaction time, response
accuracy) yielded no significant group effects. When each active
task was compared to baseline, all 3 groups showed increased
activity in the anterior cingulate and the posterior temporal gyri.
Only Thai listeners showed increased activity in the
left
frontal operculum to the tone task compared to other tasks.
Chinese and English listeners showed increased activity in the
insula to speech stimuli compared to silence. Results suggest that
patterns of cortical activity differ as a function of linguistic
experience, and that the functional anatomy subserving perception
of language stimuli may vary depending on listener processing
strategy.
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