Short-term musical intervention enhances infants' neural processing of temporal structure in music and speech

Thesis (Ph.D.)--University of Washington, 2015Early music training provides an excellent model for studying neural plasticity and understanding the relations between music and speech processing; and it has implications for speech and language development. Most of the recent experimental evidence comes from cross-sectional studies of individuals with different music learning backgrounds. Data from these studies suggest an experience-related enhancement for high-level music pitch processing (e.g. chord and melody processing), and generalization to pitch processing in speech. However, little is known about processing in the temporal domain, where critical information lies both in music and speech, especially at the level of temporal structure. In music, temporal structure (e.g., meter) groups beats into units to help generate differential expectations for strong and weak beats (marching vs. waltz). In speech, temporal structure carries critical information such as syllable structure. The current study aimed to elucidate the effect of a short-term music intervention on infants' neural processing of temporal structure in music and speech using a random-assignment approach. Forty-seven 9-month-olds were randomly assigned to complete 12 sessions (~4 wks) of social, multimodal music intervention (Intervention group) or 12 sessions of social free play (Control group). The mismatch response (MMR) was the target neural measure used to quantify infants' processing of temporal structure both in music and in speech after the intervention/control sessions. Using Magnetoencephalography (MEG) with good spatial resolution, we compared the MMRs in the temporal cortical regions as well as in the prefrontal regions between the Intervention and the Control groups. The results showed that the Intervention group exhibited larger MMRs in both temporal and prefrontal regions than their Control group counterparts, indicating stronger ability to track high-level temporal structure, as hypothesized. It is the first known experiment demonstrating an effect of music intervention in the temporal information processing domain in infancy, and the first to show generalization from music intervention to speech processing in infancy. The results provide important implications for our understanding of auditory experience-related effects on music and speech early in development