Echolocating bats rely upon spectral interference patterns in echoes to reconstruct fine details of a reflecting object’s shape. However, the acoustic modulations required to do this are extremely brief, raising questions about how their auditory cortex encodes and processes such rapid and fine spectrotemporal details. Here, we tested the hypothesis that biosonar target shape representation in the primary auditory cortex (A1) is more reliably encoded by changes in spike timing (latency) than spike rates and that latency is sufficiently precise to support a synchronization-based ensemble representation of this critical auditory object feature space. To test this, we measured how the spatiotemporal activation patterns of A1 changed when naturalistic spectral notches were inserted into echo mimic stimuli. Neurons tuned to notch frequencies were predicted to exhibit longer latencies and lower mean firing rates due to lower signal amplitudes at their preferred frequencies, and both were found to occur. Comparative analyses confirmed that significantly more information was recoverable from changes in spike times relative to concurrent changes in spike rates. With this data, we reconstructed spatiotemporal activation maps of A1 and estimated the level of emerging neuronal spike synchrony between cortical neurons tuned to different frequencies. The results support existing computational models, indicating that spectral interference patterns may be efficiently encoded by a cascading tonotopic sequence of neural synchronization patterns within an ensemble of network activity that relates to the physical features of the reflecting object surface.

定位蝙蝠依靠回波中的频谱干涉图来重构反射物体形状的精细细节。但是，执行此操作所需的声学调制非常简短，这引发了有关其听觉皮层如何编码和处理这种快速且精细的光谱时态细节的问题。在这里，我们测试了以下假设：主峰听觉皮层（A1）中的生物声目标形状表示比峰值速率更可靠地由峰值定时（潜伏期）的变化编码，并且潜伏期足够精确，可以支持基于同步的集合表示。关键听觉对象特征空间。为了测试这一点，我们测量了将自然光谱缺口插入回波模拟刺激中时A1的时空激活模式如何变化。预测调谐到陷波频率的神经元会表现出更长的等待时间和更低的平均发动频率，这是因为它们的首选频率处的信号幅度较低，并且发现两者均会发生。比较分析证实，相对于同时发生的尖峰速率变化，从尖峰时间的变化中可以发现更多的信息。有了这些数据，我们重建了A1的时空激活图，并估计了调谐到不同频率的皮层神经元之间出现的神经元突波同步水平。结果支持现有的计算模型，表明频谱干涉图样可以由与反射物体表面的物理特征相关的网络活动整体内的神经同步图谱的级联色调序列有效编码。