Heil P
Department of Psychology, Monash University, Clayton, Victoria, Australia.
Acta Otolaryngol Suppl. 1997;532:99-102. doi: 10.3109/00016489709126152.
The timing of the phasic responses of neurons in cat primary auditory cortex to linear frequency modulated (FM) sweeps was studied and compared in detail with the neurons-responses to tone bursts of different frequencies. FM sweeps differed in direction and rate of change of frequency (RCF) and entirely traversed the neuron's excitatory frequency response area. It is demonstrated that a neuron's response to FM sweeps in a given direction is initiated whenever the instantaneous frequency of the sweep reaches a particular value, the effective Fi, independent of RCF. Effective Fi for upward and downward sweeps are closely associated with the steepest slopes of the neuron's tone burst frequency response function below and above the best frequency, respectively. This predictability of response timing appears ideal for encoding of FM parameters, such as direction, RCF, and form of modulation (e.g. linear, exponential) in the spatiotemporal pattern of excitation and in the inter-response-intervals of different neurons, i.e. in latency place codes.
研究了猫初级听觉皮层中神经元对线性调频（FM）扫描的相位响应时间，并将其与神经元对不同频率短音的响应进行了详细比较。FM扫描在频率变化方向和变化率（RCF）上有所不同，并且完全跨越了神经元的兴奋性频率响应区域。结果表明，无论扫描的RCF如何，只要扫描的瞬时频率达到特定值（有效Fi），神经元就会在给定方向上对FM扫描产生响应。向上和向下扫描的有效Fi分别与最佳频率以下和以上的神经元短音频率响应函数的最陡斜率密切相关。响应时间的这种可预测性似乎非常适合在兴奋的时空模式以及不同神经元的响应间隔中，即潜伏期位置编码中，对FM参数进行编码，如方向、RCF和调制形式（如线性、指数）。
