Infant brain development incorporates several intermingled mechanisms leading to intense and asynchronous maturation across cerebral networks and functional modalities. Combining electroencephalography (EEG) and diffusion magnetic resonance imaging (MRI), previous studies in the visual modality showed that the functional maturation of the event-related potentials (ERP) during the first postnatal semester relates to structural changes in the corresponding white matter pathways. Here investigated similar issues in the auditory modality. We measured ERPs to syllables in 1- to 6-month-old infants and related them to the maturational properties of underlying neural substrates measured with diffusion tensor imaging (DTI). We first observed a decrease in the latency of the auditory P2, and in the diffusivities in the auditory tracts and perisylvian regions with age. Secondly, we highlighted some of the early functional and structural substrates of lateralization. Contralateral responses to monoaural syllables were stronger and faster than ipsilateral responses, particularly in the left hemisphere. Besides, the acoustic radiations, arcuate fasciculus, middle temporal and angular gyri showed DTI asymmetries with a more complex and advanced microstructure in the left hemisphere, whereas the reverse was observed for the inferior frontal and superior temporal gyri. Finally, after accounting for the age-related variance, we correlated the inter-individual variability in P2 responses and in the microstructural properties of callosal fibers and inferior frontal regions. This study combining dedicated EEG and MRI approaches in infants highlights the complex relation between the functional responses to auditory stimuli and the maturational properties of the corresponding neural network.

婴儿的大脑发育融合了多种相互交织的机制，从而导致整个大脑网络和功能模式的强烈和异步成熟。结合脑电图（EEG）和扩散磁共振成像（MRI），先前在视觉方式上的研究表明，产后第一学期事件相关电位（ERP）的功能成熟与相应的白质途径的结构变化有关。在这里调查了听觉模态中的类似问题。我们测量了1至6个月大婴儿的音节的ERPs，并将它们与通过扩散张量成像（DTI）测量的基础神经基质的成熟特性相关。我们首先观察到听觉P2潜伏期的减少，以及随着年龄的增长，听觉和周围神经的扩散性。其次，我们重点介绍了侧向化的一些早期功能和结构基础。对单耳音节的对侧反应比同侧反应更强，更快，尤其是在左半球。此外，声辐射，弓形筋膜，颞中回和角回均显示出DTI不对称，左半球的显微结构更为复杂和先进，而额下回和颞上回则相反。最后，在考虑了与年龄有关的方差后，我们将个体间的P2响应变异性以及in纤维和额叶下部的微结构特性关联起来。