Eggermont J J
Neuroscience Research Group, Department of Physiology, University of Calgary, 2500 University Drive N.W., Calgary, AB, Canada T2N 1N4.
Hear Res. 2001 Jul;157(1-2):1-42. doi: 10.1016/s0378-5955(01)00259-3.
This review investigates the roles of representation, transformation and coding as part of a hierarchical process between sound and perception. This is followed by a survey of how speech sounds and elements thereof are represented in the activity patterns along the auditory pathway. Then the evidence for a place representation of texture features of sound, comprising frequency, periodicity pitch, harmonicity in vowels, and direction and speed of frequency modulation, and for a temporal and synchrony representation of sound contours, comprising onsets, offsets, voice onset time, and low rate amplitude modulation, in auditory cortex is reviewed. Contours mark changes and transitions in sound and auditory cortex appears particularly sensitive to these dynamic aspects of sound. Texture determines which neurons, both cortical and subcortical, are activated by the sound whereas the contours modulate the activity of those neurons. Because contours are temporally represented in the majority of neurons activated by the texture aspects of sound, each of these neurons is part of an ensemble formed by the combination of contour and texture sensitivity. A multiplexed coding of complex sound is proposed whereby the contours set up widespread synchrony across those neurons in all auditory cortical areas that are activated by the texture of sound.
本综述探讨了表征、转换和编码在声音与感知之间的分层过程中的作用。接下来，我们将审视语音及其元素在听觉通路活动模式中的表征方式。然后，我们将回顾关于声音纹理特征（包括频率、周期性音高、元音中的谐波性以及频率调制的方向和速度）的位置表征，以及关于声音轮廓（包括起始、结束、语音起始时间和低速幅度调制）在听觉皮层中的时间和同步表征的证据。轮廓标志着声音中的变化和过渡，而听觉皮层似乎对声音的这些动态方面特别敏感。纹理决定了皮层和皮层下的哪些神经元会被声音激活，而轮廓则调节这些神经元的活动。由于轮廓在大多数由声音纹理方面激活的神经元中是按时间表征的，因此这些神经元中的每一个都是由轮廓和纹理敏感性组合形成的集合的一部分。本文提出了一种复杂声音的复用编码方式，即轮廓在所有由声音纹理激活的听觉皮层区域的那些神经元之间建立广泛的同步。
