Musical intervention enhances infants' neural processing of temporal structure in music and speech

Abstract

Individuals with music training in early childhood show enhanced processing of musical sounds, an effect that generalizes to speech processing. However, the conclusions drawn from previous studies are limited due to the possible confounds of predisposition and other factors affecting musicians and nonmusicians. We used a randomized design to test the effects of a laboratory-controlled music intervention on young infants' neural processing of music and speech. Nine-month-old infants were randomly assigned to music (intervention) or play (control) activities for 12 sessions. The intervention targeted temporal structure learning using triple meter in music (e.g., waltz), which is difficult for infants, and it incorporated key characteristics of typical infant music classes to maximize learning (e.g., multimodal, social, and repetitive experiences). Controls had similar multimodal, social, repetitive play, but without music. Upon completion, infants' neural processing of temporal structure was tested in both music (tones in triple meter) and speech (foreign syllable structure). Infants' neural processing was quantified by the mismatch response (MMR) measured with a traditional oddball paradigm using magnetoencephalography (MEG). The intervention group exhibited significantly larger MMRs in response to music temporal structure violations in both auditory and prefrontal cortical regions. Identical results were obtained for temporal structure changes in speech. The intervention thus enhanced temporal structure processing not only in music, but also in speech, at 9 mo of age. We argue that the intervention enhanced infants' ability to extract temporal structure information and to predict future events in time, a skill affecting both music and speech processing.

Keywords: MEG; early experience; infants; music; speech.

Fig. 1.

Music condition (MEG). (A) Schematics of stimuli. Standard and deviant sounds are acoustically identical, and deviants violate the standard temporal structure. (B, Top) The group average of the difference waves for the temporal regions of the cortex for the intervention group and the control group. The shaded region indicates the selected time window for the MMR. Time 0 marks the onset of the strong beat. (Bottom) The group average of the difference waves for the prefrontal regions of the cortex for the intervention group and the control group. (C) Mean MMR values within the target time window by region (temporal region vs. prefrontal region) and group (intervention vs. control).

Fig. 2.

Speech condition (MEG). (A) Schematics of stimuli. Deviants /bibi/ violate the syllable structure of /bibbi/. In a separate recording (Bottom), /bibi/ served as standards in a constant stream. (B, Top) The group average of the difference waves for the temporal regions of the cortex for the intervention group and the control group. The shaded region indicates the selected time window for the MMR, shifted accordingly with the onset of violation (210 ms after the onset of the nonword /bibi/, marked by time 0). (Bottom) The group average of the difference waves for the prefrontal regions of the cortex for the intervention group and the control group. (C) Mean MMR values within the target time window by region (temporal region vs. prefrontal region) and group (intervention vs. control).

Fig. 3.

(A) Music condition (sensor data from one participant). Red line, averaged epochs for standards; green line, average epochs for deviants; blue line, difference between standards and deviants. Two channels were selected to illustrate responses to the standards and deviants as well as the difference waves in the temporal and frontal areas at the sensor level. (B) Speech condition (sensor data from one participant). Red line, averaged epochs for /bibi/, serving as standards; green line, average epochs for /bibi/ deviants; blue line, difference between /bibi/ serving as standards and deviants. Two channels were selected to illustrate responses to the standards and deviants as well as the difference waves in the temporal and frontal areas at the sensor level.