Schulze H, Ohl F W, Heil P, Scheich H
Federal Institute for Neurobiology (IfN), Magdeburg, Germany.
J Comp Physiol A. 1997 Dec;181(6):573-89. doi: 10.1007/s003590050141.
Responses of multi-units in the auditory cortex (AC) of unanaesthetized Mongolian gerbils to pure tones and to linearly frequency modulated (FM) sounds were analysed. Three types of responses to pure tones could be clearly distinguished on the basis of spectral tuning properties, response latencies and overall temporal response pattern. In response to FM sweeps these three types discharged in a temporal pattern similar to tone responses. However, for all type-1 units the latencies of some phasic response components shifted systematically as a function of range and/or speed of modulation. Measurements of response latencies to FMs revealed that such responses were evoked whenever the modulation reached a particular instantaneous frequency (Fi). Effective Fi was: (1) independent of modulation range and speed, (2) always reached before the modulation arrived at a local maximum of the frequency response function (FRF) and consequently differed for downward and upward sweeps, and (3) was correlated with the steepest slope of that FRF maximum. The three different types of units were found in discrete and separate fields or regions of the AC. It is concluded that gross temporal response properties are one of the key features distinguishing auditory cortical regions in the Mongolian gerbil.
分析了未麻醉的蒙古沙鼠听觉皮层（AC）中多单元对纯音和线性调频（FM）声音的反应。根据频谱调谐特性、反应潜伏期和整体时间反应模式，可以清楚地区分出对纯音的三种反应类型。对FM扫描的反应中，这三种类型以类似于纯音反应的时间模式放电。然而，对于所有1型单元，一些相位反应成分的潜伏期会根据调制范围和/或速度系统地变化。对FM反应潜伏期的测量表明，只要调制达到特定的瞬时频率（Fi），就会引发这种反应。有效Fi为：（1）与调制范围和速度无关；（2）总是在调制到达频率反应函数（FRF）的局部最大值之前达到，因此向下和向上扫描时不同；（3）与该FRF最大值的最陡斜率相关。在AC的离散和独立区域发现了三种不同类型的单元。得出的结论是，总体时间反应特性是区分蒙古沙鼠听觉皮层区域的关键特征之一。
