Processing of modulated sounds in the zebra finch auditory midbrain: responses to noise, frequency sweeps, and sinusoidal amplitude modulations.
Processing of modulated sounds in the zebra finch auditory midbrain: responses to noise, frequency sweeps, and sinusoidal amplitude modulations.
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DOI：
10.1152/jn.01064.2004
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发表时间：
2005-08
影响因子：
2.5
通讯作者：
Sarah M. N. Woolley;J. H. Casseday
中科院分区：
文献类型：
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作者：
Sarah M. N. Woolley;J. H. Casseday
鸟类听觉中脑核（mesencephalicus lateralis，dorsalis，MLd）是多个平行输入汇聚的第一个听觉加工阶段，它将输入提供给听觉丘脑。我们研究了单个MLd神经元对四种调制声音的反应：1）白色噪声; 2）带限噪声; 3）调频（FM）扫描; 4）正弦幅度调制音调（SAM）在成年雄性斑胸草雀。反应进行了比较与相同的神经元纯音的时间响应模式，阈值，特征频率，频率调谐带宽，调谐锐度，和尖峰率/强度的关系。大多数神经元对噪音反应良好。超过一半的神经元选择性地对噪声的特定部分做出反应，这表明与前脑神经元不同，许多MLd神经元可以编码高度调制的声音（如噪声）的特定声学成分。只有13%的对扫描有反应的细胞对FM扫描方向有选择性。这些细胞也表现出不对称的调谐曲线，这表明不对称抑制在FM方向选择性中起作用。对SAM的反应表明，MLd神经元编码的时间调制率使用的尖峰速率和同步。几乎所有的细胞都表现出低通或带通滤波特性的SAM。最佳调制频率与斑胸草雀鸣叫的时间调制相匹配。结果表明，听觉中脑神经元非常适合编码广泛的复杂的声音，具有高度的时间准确性，而不是选择性地只对某些声音作出反应。
The avian auditory midbrain nucleus, the mesencephalicus lateralis, dorsalis (MLd), is the first auditory processing stage in which multiple parallel inputs converge, and it provides the input to the auditory thalamus. We studied the responses of single MLd neurons to four types of modulated sounds: 1) white noise; 2) band-limited noise; 3) frequency modulated (FM) sweeps, and 4) sinusoidally amplitude-modulated tones (SAM) in adult male zebra finches. Responses were compared with the responses of the same neurons to pure tones in terms of temporal response patterns, thresholds, characteristic frequencies, frequency tuning bandwidths, tuning sharpness, and spike rate/intensity relationships. Most neurons responded well to noise. More than one-half of the neurons responded selectively to particular portions of the noise, suggesting that, unlike forebrain neurons, many MLd neurons can encode specific acoustic components of highly modulated sounds such as noise. Selectivity for FM sweep direction was found in only 13% of cells that responded to sweeps. Those cells also showed asymmetric tuning curves, suggesting that asymmetric inhibition plays a role in FM directional selectivity. Responses to SAM showed that MLd neurons code temporal modulation rates using both spike rate and synchronization. Nearly all cells showed low-pass or band-pass filtering properties for SAM. Best modulation frequencies matched the temporal modulations in zebra finch song. Results suggest that auditory midbrain neurons are well suited for encoding a wide range of complex sounds with a high degree of temporal accuracy rather than selectively responding to only some sounds.