Cortical specialization for music in preverbal infants

Audition 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.