Cortical Activation Patterns Evoked by Temporally Asymmetric Sounds and Their Modulation by Learning.
Cortical Activation Patterns Evoked by Temporally Asymmetric Sounds and Their Modulation by Learning.
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DOI：
10.1523/eneuro.0241-16.2017
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发表时间：
2017-03
期刊：
影响因子：
3.4
通讯作者：
Ojima H
中科院分区：
文献类型：
--
作者：
Horikawa J;Ojima H
当复杂的声音在时间上颠倒时，原始版本和颠倒版本在频谱和时间维度上的感知是不同的，尽管它们的持续时间和长期频谱功率分布相同。由时间上不对称的声音对引起的时空激活模式展示了时间包络如何决定频谱的读出。我们研究了时间上不对称的声音对在麻醉豚鼠的初级听野(AI)中诱发的激活模式，并确定了辨别训练如何改变这些模式。使用电压敏感染料的光学成像显示，正向降低的自然声(F)始终比时间反转的增强的自然声(RevF)产生更强的反应。F诱发的激活的时空最大峰值(Max P)始终大于RevF诱发的激活的时空最大峰值(Max P)，且这两个max在AI内显著分离。尽管辨别训练不影响这些MAXP的绝对大小，但训练组在大脑半球最大激活位置(即F诱发的MAXP)计算的激活峰的RevF/F比率明显较小。F-诱发的激活沿时间轴穿过AI传至腹前带区，训练组VA内的局部激活峰值显著大于单纯训练组。这些结果表明，与生俱来的网络对倾斜信封的自然声音比它们的时间反转的非自然声音更有反应。VA带野的激活可能通过其与杏仁核的联系，在声音的情绪学习中发挥重要作用。
When complex sounds are reversed in time, the original and reversed versions are perceived differently in spectral and temporal dimensions despite their identical duration and long-term spectrum-power profiles. Spatiotemporal activation patterns evoked by temporally asymmetric sound pairs demonstrate how the temporal envelope determines the readout of the spectrum. We examined the patterns of activation evoked by a temporally asymmetric sound pair in the primary auditory field (AI) of anesthetized guinea pigs and determined how discrimination training modified these patterns. Optical imaging using a voltage-sensitive dye revealed that a forward ramped-down natural sound (F) consistently evoked much stronger responses than its time-reversed, ramped-up counterpart (revF). The spatiotemporal maximum peak (maxP) of F-evoked activation was always greater than that of revF-evoked activation, and these maxPs were significantly separated within the AI. Although discrimination training did not affect the absolute magnitude of these maxPs, the revF-to-F ratio of the activation peaks calculated at the location where hemispheres were maximally activated (i.e., F-evoked maxP) was significantly smaller in the trained group. The F-evoked activation propagated across the AI along the temporal axis to the ventroanterior belt field (VA), with the local activation peak within the VA being significantly larger in the trained than in the naïve group. These results suggest that the innate network is more responsive to natural sounds of ramped-down envelopes than their time-reversed, unnatural sounds. The VA belt field activation might play an important role in emotional learning of sounds through its connections with amygdala.