Malmierca Manuel S, Izquierdo Marco A, Cristaudo Salvatore, Hernández Olga, Pérez-González David, Covey Ellen, Oliver Douglas L
Auditory Neurophysiology Unit, Laboratory for the Neurobiology of Hearing, Faculty of Medicine, University of Salamanca, 37007 Salamanca, Spain.
J Neurosci. 2008 Apr 30;28(18):4767-76. doi: 10.1523/JNEUROSCI.0238-08.2008.
Audible frequencies of sound are encoded in a continuous manner along the length of the cochlea, and frequency is transmitted to the brain as a representation of place on the basilar membrane. The resulting tonotopic map has been assumed to be a continuous smooth progression from low to high frequency throughout the central auditory system. Here, physiological and anatomical data show that best frequency is represented in a discontinuous manner in the inferior colliculus, the major auditory structure of the midbrain. Multiunit maps demonstrate a distinct stepwise organization in the order of best frequency progression. Furthermore, independent data from single neurons show that best frequencies at octave intervals of approximately one-third are more prevalent than others. These data suggest that, in the inferior colliculus, there is a defined space of tissue devoted to a given frequency, and input within this frequency band may be pooled for higher-level processing.
可听声频率沿耳蜗长度以连续方式编码，并且频率作为基底膜上位置的表征传递至大脑。由此产生的音频拓扑图被认为在整个中枢听觉系统中是从低频到高频的连续平滑进展。在此，生理学和解剖学数据表明，最佳频率在中脑的主要听觉结构下丘中以不连续方式呈现。多单元图谱显示出最佳频率进展顺序中独特的阶梯式组织。此外，来自单个神经元的独立数据表明，大约三分之一倍频程间隔的最佳频率比其他频率更普遍。这些数据表明，在下丘中，存在专门用于给定频率的特定组织空间，并且该频带内的输入可能会被集中用于更高层次的处理。
