Early musical training and white-matter plasticity in the corpus callosum: evidence for a sensitive period

Abstract

Training during a sensitive period in development may have greater effects on brain structure and behavior than training later in life. Musicians are an excellent model for investigating sensitive periods because training starts early and can be quantified. Previous studies suggested that early training might be related to greater amounts of white matter in the corpus callosum, but did not control for length of training or identify behavioral correlates of structural change. The current study compared white-matter organization using diffusion tensor imaging in early- and late-trained musicians matched for years of training and experience. We found that early-trained musicians had greater connectivity in the posterior midbody/isthmus of the corpus callosum and that fractional anisotropy in this region was related to age of onset of training and sensorimotor synchronization performance. We propose that training before the age of 7 years results in changes in white-matter connectivity that may serve as a scaffold upon which ongoing experience can build.

Figure 1.

Behavioral task and group performance data. A, Temporal motor sequence task. The learned sequence, visually presented stimuli, and response method are shown. B, Performance data from the TMST. PCOR and PSYN are shown across blocks. Group means for each measure are plotted for each day (d) and block (b): ET are shown in red, LT in blue, and NM in black. Error bars depict ±SEM. The vertical dotted line between d1b3 and d2b1 denotes the boundary between days of training.

Figure 2.

ET versus LT group FA differences and extractions. A, ET > LT group difference in skeletonized FA (blue) in posterior midbody of the corpus callosum. The tract based on this seed connects the right and left sensorimotor cortices and is represented as the red-yellow underlay (where red represents a threshold of 1–10% of maximum particle count and bright yellow depicts 10% and greater). B, FA (top) and RD (bottom) values from the peak CC voxel plotted against group, age of onset, and PSYN Final. Values for ET are depicted in red, LT in blue, and NM in black. Group means are depicted with filled circles. Raw values were used for all plots while statistics were based on the corrected values as stated in the text. **p < 0.001.

Figure 3.

Correlation between FA and age of onset of musical training. FA was significantly correlated with age of onset of musical training across musicians in bilateral rostral body and midbody of the corpus callosum (red). This region overlaps with the more posterior midbody location identified in the group contrast between ET and LT (overlayed in semitransparent blue visible in the top left and bottom right slices).

Figure 4.

Whole-brain FA correlations with PSYN Final. A, Skeleton voxels significantly correlated with PSYN Final in left temporal lobe and posterior limb of the internal and external capsules (blue). B, Mean values extracted from the region of significant correlation plotted against group, age of onset, and PSYN Final. ET are shown in red, LT in blue, and NM in black. Group means are depicted with filled circles. Note that raw values were used for all plots while statistics were based on the corrected values as stated in the text. *p < 0.05.