Institute for Cell Biology and Neuroscience, Goethe University, Frankfurt/Main, Germany.
J Acoust Soc Am. 2013 Jan;133(1):570-8. doi: 10.1121/1.4768794.
Delay tuning was studied in the auditory cortex of Pteronotus quadridens. All the 136 delay-tuned units that were studied responded strongly to heteroharmonic pulse-echo pairs presented at specific delays. In the heteroharmonic pairs, the first sonar call harmonic marks the timing of pulse emission while one of the higher harmonics (second or third) indicates the timing of the echo. Delay-tuned units are organized chronotopically along a rostrocaudal axis according to their characteristic delay. There is no obvious indication of multiple cortical axes specialized in the processing of different harmonic combinations of pulse and echo. Results of this study serve for a straight comparison of cortical delay-tuning between P. quadridens and the well-studied mustached bat, Pteronotus parnellii. These two species stem from the most recent and most basal nodes in the Pteronotus lineage, respectively. P. quadridens and P. parnellii use comparable heteroharmonic target-range computation strategies even though they do not use biosonar calls of a similar design. P. quadridens uses short constant-frequency (CF)/frequency-modulated (FM) echolocation calls, while P. parnellii uses long CF/FM calls. The ability to perform "heteroharmonic" target-range computations might be an ancestral neuronal specialization of the genus Pteronotus that was subjected to positive Darwinian selection in the evolution.
延迟调谐在 Pteronotus quadridens 的听觉皮层中进行了研究。所有研究的 136 个延迟调谐单元对特定延迟下呈现的异谐波脉冲回波对反应强烈。在异谐波对中，第一个声纳呼叫谐波标记脉冲发射的时间，而较高谐波之一（第二或第三）指示回波的时间。根据其特征延迟，沿前后轴组织延迟调谐单元。没有明显的迹象表明存在多个专门处理脉冲和回波不同谐波组合的皮质轴。这项研究的结果可用于 P. quadridens 和研究充分的鬃毛蝙蝠 Pteronotus parnellii 之间皮质延迟调谐的直接比较。这两个物种分别来自 Pteronotus 谱系中最近和最基础的节点。尽管它们不使用类似设计的生物声纳叫声，但 P. quadridens 和 P. parnellii 使用可比的异谐波目标范围计算策略。P. quadridens 使用短的恒定频率（CF）/调频（FM）回声定位叫声，而 P. parnellii 使用长的 CF/FM 叫声。执行“异谐波”目标范围计算的能力可能是 Pteronotus 属的祖先神经元专业化，它在进化中受到了正达尔文选择的影响。
