Harrison R V, Ibrahim D, Mount R J
Department of Otolaryngology, Hospital for Sick Children, Toronto, Canada.
Exp Brain Res. 1998 Dec;123(4):449-60. doi: 10.1007/s002210050589.
There is substantial reorganization of the midbrain (inferior colliculus) tonotopic map following neonatally induced partial cochlear lesions in the chinchilla. The most obvious feature of this remapping is a large "iso-frequency" region in the ventral sector of the central nucleus of inferior colliculus (ICC). Neurons in this region exhibit similar threshold and tuning properties, with a common characteristic frequency which corresponds to the high-frequency audiometric cutoff. This overrepresented frequency range also corresponds to the high-frequency border of the cochlear lesion. Alterations to the tonotopic map corresponding to lower frequencies, in more dorsal regions of ICC, depend on the extent and degree of the cochlear lesion. When there is minimal damage to apical (low-frequency) cochlear areas, the dorsal ICC has relatively normal frequency representations. With more extensive apical cochlear lesions there is a corresponding disruption of ICC tonotopic representation of the low frequencies. We conclude that the tonotopic map within the ICC can become (re)organized postnatally according to the abnormal pattern of neural activity from the auditory periphery. Similar reorganization can be expected to occur in human infants with a partial cochlear hearing loss from birth.
在新生期诱导的灰鼠部分耳蜗损伤后，中脑（下丘）音频拓扑图会发生显著重组。这种重新映射最明显的特征是在下丘中央核（ICC）腹侧部分有一个大的“等频率”区域。该区域的神经元表现出相似的阈值和调谐特性，具有一个共同的特征频率，该频率对应于高频听力截止点。这个过度代表的频率范围也对应于耳蜗损伤的高频边界。在ICC更靠背侧区域中，对应于较低频率的音频拓扑图的改变取决于耳蜗损伤的范围和程度。当耳蜗顶部（低频）区域损伤很小时，背侧ICC具有相对正常的频率表征。随着耳蜗顶部损伤范围扩大，低频的ICC音频拓扑表征会相应受到破坏。我们得出结论，ICC内的音频拓扑图可在出生后根据听觉外周神经活动的异常模式进行（重新）组织。预计出生时患有部分耳蜗性听力损失的人类婴儿也会发生类似的重组。
