Virtual adult ears reveal the roles of acoustical factors and experience in auditory space map development.
Virtual adult ears reveal the roles of acoustical factors and experience in auditory space map development.
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DOI：
10.1523/jneurosci.0545-08.2008
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发表时间：
2008-11-05
期刊：
影响因子：
--
通讯作者：
Doubell TP
中科院分区：
文献类型：
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作者：
Campbell RA;King AJ;Nodal FR;Schnupp JW;Carlile S;Doubell TP
上级丘（SC）中的听觉神经元优先对来自受限方向的声音作出反应，以形成听觉空间的地图。这种表征的发展是由感官经验塑造的，但我们对周边和中枢因素对成人反应的出现的相对贡献知之甚少。通过记录从SC的麻醉雪貂在不同的年龄点，我们表明，地图逐渐成熟后出生的空间感受野（SRFs）变得更加尖锐的调整和地形秩序出现的第二个月后结束。头相关的传递函数的主成分分析表明，映射发展的时间过程是反映了由不断增长的头部和外耳产生的空间线索的成熟。然而，使用虚拟的声学空间刺激，我们表明，这些声学变化本身并不负责SC地图地形的出现。提出刺激婴儿雪貂通过虚拟成人的耳朵并没有改善的顺序在SC中的声音方位角的表示。但使用线性判别分析，比较不同的响应特性，跨年龄，我们发现，婴儿神经元的SRF然而变得更成人一样，当刺激通过虚拟成人的耳朵。因此，虽然听觉地形图的出现很可能取决于神经回路的改进，但SRF结构（特别是其空间范围）的成熟在很大程度上可以通过与头部和耳朵生长相关的声学变化来解释。
Auditory neurons in the superior colliculus (SC) respond preferentially to sounds from restricted directions to form a map of auditory space. The development of this representation is shaped by sensory experience, but little is known about the relative contribution of peripheral and central factors to the emergence of adult responses. By recording from the SC of anesthetized ferrets at different age points, we show that the map matures gradually after birth; the spatial receptive fields (SRFs) become more sharply tuned and topographic order emerges by the end of the second postnatal month. Principal components analysis of the head-related transfer function revealed that the time course of map development is mirrored by the maturation of the spatial cues generated by the growing head and external ears. However, using virtual acoustic space stimuli, we show that these acoustical changes are not by themselves responsible for the emergence of SC map topography. Presenting stimuli to infant ferrets through virtual adult ears did not improve the order in the representation of sound azimuth in the SC. But using linear discriminant analysis to compare different response properties across age, we found that the SRFs of infant neurons nevertheless became more adult-like when stimuli were delivered through virtual adult ears. Hence, although the emergence of auditory topography is likely to depend on refinements in neural circuitry, maturation of the structure of the SRFs (particularly their spatial extent) can be largely accounted for by changes in the acoustics associated with growth of the head and ears.