Department of Neuroscience, Box GLN, Brown University, Providence, RI 02912, USA.
Curr Opin Neurobiol. 2012 Apr;22(2):311-9. doi: 10.1016/j.conb.2012.02.007. Epub 2012 Mar 19.
This paper reexamines neurophysiological results from echolocating big brown bats to propose a new perspective on FM biosonar processing in the auditory system. Individual auditory neurons are frequency-tuned and respond to brief, 2-10 ms FM sweeps with an average of one spike per sound to register their tuned frequencies, to detect echo arrival, or to register a local null in the echo spectrum. When initiated by the broadcast, these responses comprise a cascade of single spikes distributed across time in neurons tuned to different frequencies that persists for 30-50 ms, long after the sound has ended. Their progress mirrors the broadcast's propagation away from the bat and the return of echoes for distances out to 5-8 m. Each returning echo evokes a similar pattern of single spikes that coincide with ongoing responses to the broadcast to register the target's distance and shape. The hypothesis advanced here is that this flow of responses over time acts as an internal model of sonar acoustics that the bat executes using neuronal computations distributed across many neurons to accumulate a dynamic image of the bat's surroundings.
本文重新审视了回声定位大褐蝙蝠的神经生理学结果，提出了一种关于听觉系统中调频生物声纳处理的新观点。单个听觉神经元具有频率调谐性，对持续 2-10 毫秒的 FM 扫频做出反应，平均每个声音有一个尖峰，以记录其调谐频率、检测回声到达或记录回声频谱中的局部零值。当由广播触发时，这些反应构成了一个在不同频率调谐的神经元中分布在时间上的一连串单个尖峰，持续 30-50 毫秒，远远超过声音结束的时间。它们的进展反映了广播从蝙蝠传播开来，以及回声返回的情况，距离可达 5-8 米。每个返回的回声都会引发类似的单个尖峰模式，与正在进行的广播反应相吻合，以记录目标的距离和形状。这里提出的假设是，这种随时间流动的反应流充当了声纳声学的内部模型，蝙蝠使用分布在许多神经元中的神经元计算来执行该模型，以积累其周围环境的动态图像。
