Browsing by Author "Fava, Eswen Elizabeth"
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Item Cortical specialization for music in preverbal infants(2009-05-15) Fava, Eswen ElizabethAudition is perhaps the most developed and acute sense available to infants at birth. One theory supported by speech and music researchers alike proposes that the auditory system is biased to salient properties such as pitch and allocates processing of such stimuli to specialized areas. In the current study, we sought to investigate whether infants would show similar patterns for processing music and language, as they both contain predictable changes in pitch. In a previous study, we established that language processing is lateralized to the left temporal region in the infant brain. We hypothesized music would be processed in the right temporal area. Although it contains a rule-based structure somewhat akin to language, it is heavily dependent on fine distinctions in pitch. Preverbal infants watched a video of animated shapes (visual stimuli) coupled with either speech (1 of 10 different stories in infant-direct speech) or music (Scriabbin's Ballade No. 3 in A flat) while hemodynamic activity in bilateral temporal sites was recording using near-infrared spectroscopy. Results indicated significant right temporal decreases in HbO2 concentration in comparison with baseline measures during music trials relative to the left temporal area. These results suggest that even at the preverbal stage, infants process speech differently than other similarly structured auditory stimuli.Item Tracking Language Tuning across the First Year of Life using Near-infrared Spectroscopy(2012-02-14) Fava, Eswen ElizabethBoth behavioral and neurophysiological data indicate that many factors contribute to how infants tune to their native language(s) in early infancy. However, substantial debate remains regarding the neural mechanisms that underlie this tuning process. This study was designed to determine whether the behavioral changes in infants' processing of native and non-native speech during the second half of the first year correspond to qualitative neural processing changes that can be measured using near-infrared spectroscopy (NIRS). Specifically, we used NIRS to examine changes in hemodynamic activity in monolingually-exposed infants between the ages of 3 and 14 months while they were exposed to native (English) and non-native (Spanish) speech. In all infants, measurements were taken from the bilateral temporal regions of the cerebral cortex. Three age groups were tested: pre-tuned infants, who should show no sensitivity to phonological differences between the native and non-native speech samples (3-to-6-month-olds), actively tuning infants, who should be beginning to differentiate between the phonology of the native and non-native speech samples (7-to-10-month-olds), and tuned infants, who should readily distinguish between the phonologies of the native and non-native speech samples (11-to-14-month-olds). Results demonstrated significant differences in hemodynamic activity during the processing of native speech compared to non-native speech in each of the three age groups, with qualitatively different patterns of hemispheric lateralization emerging in response to the two types of speech in each of the three groups. These findings point to a potential neural marker of infants' sensitivity to the phonology of their native language as it emerges with increasing age that will be useful in future research.