D'Alessandro Lisa M, Harrison Robert V
Department of Physiology, University of Toronto, Toronto, Canada M5S 1A8; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9; The Auditory Science Laboratory, Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada M5G 1X8.
Department of Physiology, University of Toronto, Toronto, Canada M5S 1A8; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9; The Auditory Science Laboratory, Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada M5G 1X8; Department of Otolaryngology-Head and Neck Surgery, University of Toronto, Toronto, Canada M5G 2N2.
Neural Plast. 2016;2016:3734646. doi: 10.1155/2016/3734646. Epub 2016 Nov 8.
Auditory brain areas undergo reorganization resulting from abnormal sensory input during early postnatal development. This is evident from studies at the cortical level but it remains unclear whether there is reorganization in the auditory midbrain in a species similar to the human, that is, with early hearing onset. We have explored midbrain plasticity in the chinchilla, a precocious species that matches the human in terms of hearing development. Neonatal chinchillas were chronically exposed to a 2 kHz narrowband sound at 70 dB SPL for 4 weeks. Tonotopic maps in inferior colliculus (central nucleus) were defined based on single neuron characteristic frequency. We hypothesized an overrepresentation of the 2 kHz region of the maps. However, we observed a significant decrease in the proportion of neurons dedicated to the 2 kHz octave band and also away from the exposure frequency at 8 kHz. In addition, we report a significant increase in low frequency representation (<1 kHz), again a change to tonotopic mapping distant to the 2 kHz region. Thus in a precocious species, tonotopic maps in auditory midbrain are altered following abnormal stimulation during development. However, these changes are more complex than the overrepresentation of exposure related frequency regions that are often reported.
在出生后早期发育过程中，听觉脑区会因异常的感觉输入而发生重组。这在皮层水平的研究中很明显，但在与人类相似的物种（即听力早期开始的物种）中，听觉中脑是否存在重组仍不清楚。我们研究了绒鼠（一种在听力发育方面与人类相似的早熟物种）中脑的可塑性。新生绒鼠在70 dB SPL的条件下长期暴露于2 kHz的窄带声音中4周。基于单个神经元的特征频率确定下丘（中央核）的音频拓扑图。我们假设该图谱中2 kHz区域会过度呈现。然而，我们观察到专门负责2 kHz倍频程带的神经元比例显著下降，并且远离8 kHz的暴露频率。此外，我们报告低频表征（<1 kHz）显著增加，同样是向远离2 kHz区域的音频拓扑映射变化。因此，在一个早熟物种中，发育过程中的异常刺激会改变听觉中脑的音频拓扑图。然而，这些变化比通常报道的与暴露相关频率区域的过度呈现更为复杂。
