Contralateral noise stimulation delays P300 latency in school-aged children

Background and objective: The auditory cortex modulates auditory afferents through the olivocochlear system, which innervates the outer hair cells and the afferent neurons under the inner hair cells in the cochlea. Most of the studies that investigated the efferent activity in humans focused on evaluating the suppression of the otoacoustic emissions by stimulating the contralateral ear with noise, which assesses the activation of the medial olivocochlear bundle. The neurophysiology and the mechanisms involving efferent activity on higher regions of the auditory pathway, however, are still unknown. Also, the lack of studies investigating the effects of noise on human auditory cortex, especially in peadiatric population, points to the need for recording the late auditory potentials in noise conditions. Assessing the auditory efferents in schoolaged children is highly important due to some of its attributed functions such as selective attention and signal detection in noise, which are important abilities related to the development of language and academic skills. For this reason, the aim of the present study was to evaluate the effects of noise on P300 responses of children with normal hearing. Methods: P300 was recorded in 27 children aged from 8 to 14 years with normal hearing in two conditions: with and whitout contralateral white noise stimulation. Results: P300 latencies were significantly longer at the presence of contralateral noise. No significant changes were observed for the amplitude values. Conclusion: Contralateral white noise stimulation delayed P300 latency in a group of school-aged children with normal hearing. These results suggest a possible influence of the medial olivocochlear activation on P300 responses under noise condition.

背景与研究目的：听觉皮层（auditory cortex）可通过橄榄耳蜗系统（olivocochlear system）对听觉传入通路进行调控，该系统可支配耳蜗（cochlea）内的外毛细胞（outer hair cells）以及内毛细胞下方的传入神经元。既往针对人类传出活动（efferent activity）的研究大多聚焦于通过噪声刺激对侧耳来评估耳声发射（otoacoustic emissions）的抑制效应，以此评价内侧橄榄耳蜗束（medial olivocochlear bundle）的激活状态。然而，针对听觉通路（auditory pathway）高级区域传出活动的神经生理学机制仍未明确。此外，目前缺乏探讨噪声对人类听觉皮层影响的相关研究，尤其是在儿科人群（pediatric population）中，这凸显了在噪声环境下记录迟发性听觉电位（late auditory potentials）的必要性。评估学龄儿童（school-aged children）的听觉传出功能具有重要意义，因为其传出系统可介导选择性注意、噪声环境下的信号检测等功能，而这些能力与语言及学业技能的发展密切相关。基于上述背景，本研究旨在探讨噪声对听力正常儿童P300反应的影响。
研究方法：本研究纳入27名年龄8~14岁的听力正常儿童，分别在对侧白噪声刺激与无对侧白噪声刺激两种条件下记录P300。
研究结果：当存在对侧噪声刺激时，P300潜伏期显著延长；而P300波幅未出现显著变化。
研究结论：对侧白噪声刺激可延迟听力正常学龄儿童的P300潜伏期，上述结果提示，内侧橄榄耳蜗束的激活可能对噪声环境下的P300反应存在调控作用。