Distinct roles for onset and sustained activity in the neuronal code for temporal periodicity and acoustic envelope shape.
Distinct roles for onset and sustained activity in the neuronal code for temporal periodicity and acoustic envelope shape.
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DOI：
10.1523/jneurosci.2882-08.2008
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发表时间：
2008-12-24
影响因子：
5.3
通讯作者：
Escabi, Monty A.
中科院分区：
文献类型：
--
作者：
Zheng, Yi;Escabi, Monty A.
关键词：
听觉神经元对时间上的声音信息具有选择性，而时间上的声音信息对于节奏、音高和音色的感知是重要的。传统的模型假设，周期性信息表示的放电率调谐调制滤波器或同步的放电模式。然而，缺乏不变速率或同步码的令人信服的证据，并且这些模型都没有说明声音包络形状是如何编码的。我们研究了猫下丘中央核（CNIC）的包络形状和周期性的神经元表示与调制宽带噪声，缺乏频谱线索，并产生一个周期性的音高感知仅基于定时信息。CNIC神经元的调制传递函数在具有相同周期性但不同包络形状的刺激条件下显著不同，这意味着形状对神经元反应有显着贡献。因此，我们设计了一个洗牌相关程序来量化周期性和包络形状如何有助于时间放电模式。持续响应在低调制速率下忠实地编码包络形状，但在高速率下恶化并且不能说明定时和包络信息。令人惊讶的是，发病反应准确地夹带到刺激，并提供了一种手段，以高速率编码重复信息。最后，我们证明，包络线形状信息准确地反映在人口放电模式，使形状很容易区分重复频率高达~100 Hz。这些结果反对传统的基于速率或同步的编码，并提供了两个互补的时间机制，CNIC神经元可以编码包络形状和重复信息的自然声音。
Auditory neurons are selective for temporal sound information that is important for rhythm, pitch, and timbre perception. Traditional models assume that periodicity information is represented either by the discharge rate of tuned modulation filters or synchrony in the discharge pattern. Compelling evidence for an invariant rate or synchrony code, however, is lacking and neither of these models account for how the sound envelope shape is encoded. We examined the neuronal representation for envelope shape and periodicity in the cat central nucleus of the inferior colliculus (CNIC) with modulated broadband noise that lack spectral cues and produce a periodicity pitch percept solely based on timing information. The modulation transfer functions of CNIC neurons differed dramatically across stimulus conditions with identical periodicity but different envelope shapes implying that shape contributed significantly to the neuronal response. We therefore devised a shuffled correlation procedure to quantify how periodicity and envelope shape contribute to the temporal discharge pattern. Sustained responses faithfully encode envelope shape at low modulation rates but deteriorate and fail to account for timing and envelope information at high rates. Surprisingly, onset responses accurately entrained to the stimulus and provided a means of encoding repetition information at high rates. Finally, we demonstrate that envelope shape information is accurately reflected in the population discharge pattern such that shape is readily discriminated for repetition frequencies up to ~100 Hz. These results argue against conventional rate or synchrony based codes and provides two complementary temporal mechanisms by which CNIC neurons can encode envelope shape and repetition information in natural sounds.