The white matter (WM) architecture of the human brain changes in response to training, though fine-grained temporal characteristics of training-induced white matter plasticity remain unexplored. We investigated white matter microstructural changes using diffusion tensor imaging at five different time points in 26 sighted female adults during 8 months of training on tactile braille reading. Our results show that training-induced white matter plasticity occurs both within and beyond the trained sensory modality, as reflected by fractional anisotropy (FA) increases in somatosensory and visual cortex, respectively. The observed changes followed distinct time courses, with gradual linear FA increase along the training in the somatosensory cortex and sudden visual cortex cross-modal plasticity occurring after braille input became linguistically meaningful. WM changes observed in these areas returned to baseline after the cessation of learning in line with the supply–demand model of plasticity. These results also indicate that the temporal dynamics of microstructural plasticity in different cortical regions might be modulated by the nature of computational demands. We provide additional evidence that observed FA training-induced changes are behaviorally relevant to tactile reading. Together, these results demonstrate that WM plasticity is a highly dynamic process modulated by the introduction of novel experiences.

SIGNIFICANCE STATEMENT Throughout the lifetime the human brain is shaped by various experiences. Training-induced reorganization in white matter (WM) microstructure has been reported, but we know little about its temporal dynamics. To fill this gap, we scanned sighted subjects five times during tactile braille reading training. We observed different dynamics of WM plasticity in the somatosensory and visual cortices implicated in braille reading. The former showed a continuous increase in WM tissue anisotropy along with tactile training, while microstructural changes in the latter were observed only after the participants learned to read braille words. Our results confirm the supply–demand model of brain plasticity and provide evidence that WM reorganization depends on distinct computational demands and functional roles of regions involved in the trained skill.

人脑的白质 (WM) 结构会随着训练而变化，尽管训练引起的白质可塑性的细粒度时间特征仍未得到探索。在 8 个月的触觉盲文阅读训练期间，我们使用弥散张量成像在 26 名视力正常的女性成年人的五个不同时间点调查了白质微观结构变化。我们的结果表明，训练诱导的白质可塑性发生在受过训练的感觉模式之内和之外，这分别反映在体感和视觉皮层的各向异性分数 (FA) 增加。观察到的变化遵循不同的时间过程，随着体感皮层训练的线性 FA 逐渐增加，盲文输入后发生的突然视觉皮层跨模态可塑性变得具有语言意义。根据可塑性的供需模型，在停止学习后，在这些区域观察到的 WM 变化恢复到基线。这些结果还表明，不同皮层区域微结构可塑性的时间动态可能受到计算需求性质的调节。我们提供了额外的证据，表明观察到的 FA 训练引起的变化与触觉阅读在行为上相关。总之，这些结果表明 WM 可塑性是一个高度动态的过程，通过引入新体验进行调节。根据可塑性的供需模型，在停止学习后，在这些区域观察到的 WM 变化恢复到基线。这些结果还表明，不同皮层区域微结构可塑性的时间动态可能受计算需求性质的调节。我们提供了额外的证据，表明观察到的 FA 训练引起的变化与触觉阅读在行为上相关。总之，这些结果表明 WM 可塑性是一个高度动态的过程，通过引入新体验进行调节。根据可塑性的供需模型，在停止学习后，在这些区域观察到的 WM 变化恢复到基线。这些结果还表明，不同皮层区域微结构可塑性的时间动态可能受到计算需求性质的调节。我们提供了额外的证据，表明观察到的 FA 训练引起的变化与触觉阅读在行为上相关。总之，这些结果表明 WM 可塑性是一个高度动态的过程，通过引入新体验进行调节。我们提供了额外的证据，表明观察到的 FA 训练引起的变化与触觉阅读在行为上相关。总之，这些结果表明 WM 可塑性是一个高度动态的过程，通过引入新体验进行调节。我们提供了额外的证据，表明观察到的 FA 训练引起的变化与触觉阅读在行为上相关。总之，这些结果表明 WM 可塑性是一个高度动态的过程，通过引入新体验进行调节。

意义声明人的大脑在一生中受到各种经历的影响。白质 (WM) 微观结构中训练诱导的重组已有报道，但我们对其时间动态知之甚少。为了填补这一空白，我们在触觉盲文阅读训练期间对视力正常的受试者进行了五次扫描。我们观察到与盲文阅读有关的体感和视觉皮质中 WM 可塑性的不同动态。前者显示 WM 组织各向异性随着触觉训练持续增加，而后者的微观结构变化仅在参与者学会阅读盲文单词后才能观察到。我们的结果证实了大脑可塑性的供需模型，并提供证据表明 WM 重组取决于不同的计算需求和训练技能所涉及区域的功能作用。