Calhoun B M, Schreiner C E
UCSF/UCB Bioengineering Graduate Group, Keck Center, University of California, San Francisco 94143-0732, USA.
Eur J Neurosci. 1998 Mar;10(3):926-40. doi: 10.1046/j.1460-9568.1998.00102.x.
Electrophysiological studies in mammal primary auditory cortex have demonstrated neuronal tuning and cortical spatial organization based upon spectral and temporal qualities of the stimulus including: its frequency, intensity, amplitude modulation and frequency modulation. Although communication and other behaviourally relevant sounds are usually complex, most response characterizations have used tonal stimuli. To better understand the mechanisms necessary to process complex sounds, we investigated neuronal responses to a specific class of broadband stimuli, auditory gratings or ripple stimuli, and compared the responses with single tone responses. Ripple stimuli consisted of 150-200 frequency components with the intensity of each component adjusted such that the envelope of the frequency spectrum is sinusoidal. It has been demonstrated that neurons are tuned to specific characteristics of those ripple stimulus including the intensity, the spacing of the peaks, and the location of the peaks and valleys (C. E. Schreiner and B. M. Calhoun, Auditory Neurosci., 1994; 1: 39-61). Although previous results showed that neuronal response strength varied with the intensity and the fundamental frequency of the stimulus, it is shown here that the relative response to different ripple spacings remains essentially constant with changes in the intensity and the fundamental frequency. These findings support a close relationship between pure-tone receptive fields and ripple transfer functions. However, variations of other stimulus characteristics, such as spectral modulation depth, result in non-linear alterations in the ripple transformation. The processing between the basilar membrane and the primary auditory cortex of broadband stimuli appears generally to be non-linear, although specific stimulus qualities, including the phase of the spectral envelope, are processed in a nearly linear manner.
对哺乳动物初级听觉皮层的电生理研究表明，基于刺激的频谱和时间特性，神经元存在调谐以及皮层空间组织，这些特性包括：频率、强度、幅度调制和频率调制。尽管交流声和其他与行为相关的声音通常很复杂，但大多数反应特征描述都使用了纯音刺激。为了更好地理解处理复杂声音所需的机制，我们研究了神经元对一类特定宽带刺激（听觉光栅或波纹刺激）的反应，并将这些反应与单音反应进行了比较。波纹刺激由150 - 200个频率成分组成，每个成分的强度经过调整，使得频谱包络呈正弦曲线。已经证明，神经元会针对那些波纹刺激的特定特征进行调谐，包括强度、峰值间距以及峰值和谷值的位置（C. E. 施赖纳和B. M. 卡尔霍恩，《听觉神经科学》，1994年；第1卷：39 - 61页）。尽管先前的结果表明神经元反应强度会随刺激的强度和基频而变化，但此处表明，随着强度和基频的变化，对不同波纹间距的相对反应基本保持不变。这些发现支持了纯音感受野与波纹传递函数之间的密切关系。然而，其他刺激特征的变化，如频谱调制深度，会导致波纹变换出现非线性改变。宽带刺激从基底膜到初级听觉皮层的处理过程总体上似乎是非线性的，尽管包括频谱包络相位在内的特定刺激特性是以近乎线性的方式进行处理的。
