Adaptation in the auditory space map of the barn owl
Adaptation in the auditory space map of the barn owl
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DOI：
10.1152/jn.01144.2005
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发表时间：
2006-08-01
影响因子：
2.5
通讯作者：
Knudsen, Eric I.
中科院分区：
文献类型：
--
作者：
Gutfreund, Yoram;Knudsen, Eric I.
猫头鹰下丘外核(ICx)中的听觉神经元通过频率通道整合信息，创建听觉空间地图。这项研究描述了ICx中一种强大的、声音驱动的对单位反应的适应，并探索了这种适应对感觉加工的影响。通过给轻度麻醉的猫头鹰呈现顺序的双耳噪声脉冲对来分析ICx中的适应。即使是对微弱的、阈值水平的声音，也会发生适应，并在刺激抵消后保持较强的状态超过100ms。由一个声音频率范围的刺激引起的适应，在这些单位对其作出反应的整个广泛的频率范围内普遍存在。使用相同的刺激来测试下丘中央核(ICCls)的外侧壳内的适应性，它直接向ICx提供输入。与ICx适应相比，ICCl中的适应明显更弱、持续时间更短、频率更具特异性，这表明ICx中观察到的适应的一部分可归因于ICx的驻留过程。ICx神经元对空间的敏锐调谐，以及它们对频率的广泛调谐，使得ICx适应保留了刺激位置的表示，而不管声音的频率内容。众所周知，ICx是视觉引导的听觉映射可塑性的场所。ICx适应可以通过提供对听觉定位线索表征的短期记忆，与来自双峰刺激的较晚到达的视觉空间信息进行比较，从而在这种跨模式可塑性中发挥作用。
Auditory neurons in the owl's external nucleus of the inferior colliculus (ICX) integrate information across frequency channels to create a map of auditory space. This study describes a powerful, sound-driven adaptation of unit responsiveness in the ICX and explores the implications of this adaptation for sensory processing. Adaptation in the ICX was analyzed by presenting lightly anesthetized owls with sequential pairs of dichotic noise bursts. Adaptation occurred in response even to weak, threshold-level sounds and remained strong for more than 100 ms after stimulus offset. Stimulation by one range of sound frequencies caused adaptation that generalized across the entire broad range of frequencies to which these units responded. Identical stimuli were used to test adaptation in the lateral shell of the central nucleus of the inferior colliculus (ICCls), which provides input directly to the ICX. Compared with ICX adaptation, adaptation in the ICCls was substantially weaker, shorter lasting, and far more frequency specific, suggesting that part of the adaptation observed in the ICX was attributable to processes resident to the ICX. The sharp tuning of ICX neurons to space, along with their broad tuning to frequency, allows ICX adaptation to preserve a representation of stimulus location, regardless of the frequency content of the sound. The ICX is known to be a site of visually guided auditory map plasticity. ICX adaptation could play a role in this cross-modal plasticity by providing a short-term memory of the representation of auditory localization cues that could be compared with later-arriving, visual-spatial information from bimodal stimuli.