Chiu T W, Poon Paul W F
Institute of Basic Medical Science, and Department of Physiology Medical College, National Cheng Kung University Tainan 701, Taiwan, ROC.
Chin J Physiol. 2007 Jun 30;50(3):105-12.
Receptive fields of single units in the auditory midbrain of anesthetized rats were studied using random FM-tone stimuli of narrow frequency-ranges. Peri-spike averaging of the modulating waveform first produced a spectro-temporal receptive field (STRF). Combining STRFs obtained from the same unit at different frequency regions generated a composite receptive field covering a wider frequency range of 2 to 3 octaves. About 20% of the composite STRFs (26/122) showed a pattern of multiple-bands which were not clear in the non-composite maps. Multiple-bands in a given composite map were often oriented in the same direction (representing upward or downward FM ramp) separated at rather regular frequency intervals. They reflect multiple FM trigger features in the stimulus rather than repetitive firing to a single trigger feature. Results showed that the subcortical auditory pathways are capable of detecting multiple FM features and such sensitivity could be useful in detecting multiple-harmonic FM bands present in the vocalization sounds.
利用窄频率范围的随机调频音调刺激，研究了麻醉大鼠听觉中脑单个神经元的感受野。对调制波形进行峰周平均，首先产生了一个频谱-时间感受野（STRF）。将从同一神经元在不同频率区域获得的STRF组合起来，生成了一个覆盖2至3个八度更宽频率范围的复合感受野。约20%的复合STRF（26/122）呈现出多带模式，这在非复合图谱中并不明显。给定复合图谱中的多带通常沿相同方向排列（代表向上或向下的调频斜坡），以相当规则的频率间隔分开。它们反映了刺激中的多个调频触发特征，而不是对单个触发特征的重复放电。结果表明，皮层下听觉通路能够检测多个调频特征，这种敏感性可能有助于检测发声声音中存在的多谐波调频带。
