Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská 1083, 14220 Prague 4, Czech Republic; Department of Technical Studies, College of Polytechnics Jihlava, Tolstého 16, 58601, Jihlava, Czech Republic; Department of Otorhinolaryngology, Third Faculty of Medicine, University Hospital Královské Vinohrady, Charles University in Prague, Šrobárova 1150/50, 10034 Prague 10, Czech Republic.
Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská 1083, 14220 Prague 4, Czech Republic.
Hear Res. 2024 Nov;453:109110. doi: 10.1016/j.heares.2024.109110. Epub 2024 Sep 5.
It has long been known that environmental conditions, particularly during development, affect morphological and functional properties of the brain including sensory systems; manipulating the environment thus represents a viable way to explore experience-dependent plasticity of the brain as well as of sensory systems. In this review, we summarize our experience with the effects of acoustically enriched environment (AEE) consisting of spectrally and temporally modulated complex sounds applied during first weeks of the postnatal development in rats and compare it with the related knowledge from the literature. Compared to controls, rats exposed to AEE showed in neurons of several parts of the auditory system differences in the dendritic length and in number of spines and spine density. The AEE exposure permanently influenced neuronal representation of the sound frequency and intensity resulting in lower excitatory thresholds, increased frequency selectivity and steeper rate-intensity functions. These changes were present both in the neurons of the inferior colliculus and the auditory cortex (AC). In addition, the AEE changed the responsiveness of AC neurons to frequency modulated, and also to a lesser extent, amplitude-modulated stimuli. Rearing rat pups in AEE leads to an increased reliability of acoustical responses of AC neurons, affecting both the rate and the temporal codes. At the level of individual spikes, the discharge patterns of individual neurons show a higher degree of similarity across stimulus repetitions. Behaviorally, rearing pups in AEE resulted in an improvement in the frequency resolution and gap detection ability under conditions with a worsened stimulus clarity. Altogether, the results of experiments show that the exposure to AEE during the critical developmental period influences the frequency and temporal processing in the auditory system, and these changes persist until adulthood. The results may serve for interpretation of the effects of the application of enriched acoustical environment in human neonatal medicine, especially in the case of care for preterm born children.
长期以来，人们已经知道环境条件，特别是在发育过程中的环境条件，会影响大脑的形态和功能特性，包括感觉系统；因此，操纵环境代表了一种可行的方法，可以探索大脑以及感觉系统的经验依赖性可塑性。在这篇综述中，我们总结了我们在大鼠出生后发育的第一周期间应用包含光谱和时间调制的复杂声音的丰富声音环境（AEE）对听觉系统的影响的经验，并将其与文献中的相关知识进行了比较。与对照组相比，暴露于 AEE 的大鼠在听觉系统的几个部分的神经元中，在树突长度和棘突数量以及棘突密度方面表现出差异。AEE 暴露永久性地影响了声音频率和强度的神经元表示，导致兴奋性阈值降低、频率选择性增加和斜率强度函数变陡。这些变化在丘脑中的神经元和听觉皮层（AC）中都存在。此外，AEE 改变了 AC 神经元对调频刺激以及调制幅度较小的刺激的反应性。在 AEE 中饲养大鼠幼仔会导致 AC 神经元对声音反应的可靠性增加，从而影响到率和时间代码。在单个尖峰的水平上，单个神经元的放电模式在刺激重复时表现出更高的相似性。在行为上，在刺激清晰度恶化的情况下，在 AEE 中饲养幼仔可提高对频率分辨率和间隙检测能力。总的来说，实验结果表明，在关键发育期间暴露于 AEE 会影响听觉系统中的频率和时间处理，并且这些变化会持续到成年期。这些结果可用于解释在人类新生儿医学中应用丰富声音环境的影响，特别是在早产儿护理的情况下。
