Electrical and Computer Engineering, University of Connecticut, Storrs, Connecticut, United States of America.
Biomedical Engineering, University of Connecticut, Storrs, Connecticut, United States of America.
PLoS Biol. 2019 Jun 24;17(6):e2005861. doi: 10.1371/journal.pbio.2005861. eCollection 2019 Jun.
Accurately resolving frequency components in sounds is essential for sound recognition, yet there is little direct evidence for how frequency selectivity is preserved or newly created across auditory structures. We demonstrate that prepotentials (PPs) with physiological properties resembling presynaptic potentials from broadly tuned brainstem inputs can be recorded concurrently with postsynaptic action potentials in inferior colliculus (IC). These putative brainstem inputs (PBIs) are broadly tuned and exhibit delayed and spectrally interleaved excitation and inhibition not present in the simultaneously recorded IC neurons (ICNs). A sharpening of tuning is accomplished locally at the expense of spike-timing precision through nonlinear temporal integration of broadband inputs. A neuron model replicates the finding and demonstrates that temporal integration alone can degrade timing precision while enhancing frequency tuning through interference of spectrally in- and out-of-phase inputs. These findings suggest that, in contrast to current models that require local inhibition, frequency selectivity can be sharpened through temporal integration, thus supporting an alternative computational strategy to quickly refine frequency selectivity.
准确解析声音中的频率成分对于声音识别至关重要，但对于频率选择性如何在听觉结构中得以保留或新产生，目前几乎没有直接证据。我们证明，具有类似于来自广泛调谐脑干输入的突触前电位的生理特性的预电位 (PP) 可以与下丘脑中的突触后动作电位同时记录。这些推测的脑干输入 (PBI) 具有广泛的调谐特性，并表现出延迟和频谱交织的兴奋和抑制，而在同时记录的下丘神经元 (ICNs) 中不存在。通过对宽带输入的非线性时间整合，在局部实现调谐的锐化，而牺牲了尖峰时间精度。神经元模型复制了这一发现，并表明仅通过时间整合就可以在增强频率调谐的同时降低时间精度，这是通过对同相和异相信号输入的干扰实现的。这些发现表明，与需要局部抑制的现有模型相反，频率选择性可以通过时间整合来锐化，从而支持一种替代的计算策略，可以快速细化频率选择性。
