Multiple sounds degrade the frequency representation in monkey inferior colliculus.
Multiple sounds degrade the frequency representation in monkey inferior colliculus.
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DOI：
10.1111/ejn.15545
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发表时间：
2022-01
影响因子：
3.4
通讯作者：
Groh, Jennifer M.
中科院分区：
文献类型：
--
作者：
Willett, Shawn M.;Groh, Jennifer M.
我们如何区分多个同时刺激是不确定的，特别是考虑到这些刺激有时会招募大量重叠的神经元群体。一个普遍提出的假设是，调谐曲线的锐度可能会改变，以限制在多个刺激存在时驱动任何给定神经元的刺激的数量。为了验证这一假设，我们记录了猴子对一个或两个频率和空间位置不同的声音进行扫视时下丘神经元的活动。尽管猴子很容易区分同时出现的声音（正确率约为90%），但在双声试验中，下丘神经元的频率选择性并没有明显改善。与单声试验相比，双声试验的频率选择性降低：神经反应函数变宽，频率占放电率方差的比例较小。神经放电的这些变化导致最大似然解码器在双音试验中的表现比在单音试验中更差。这些结果不能支持的假设，即频率响应函数的变化，以减少重叠的同时声音的表示。相反，这些结果表明，替代的可能性，如最近的证据表明，在对应于两个刺激的速率之间的放电率交替，提供了一个更有前途的方法。尽管存在粗编码，但感觉表征如何对多个刺激进行编码仍是未知的。使用最大似然解码器操作的尖峰计数响应模式的猴子下丘神经元，我们表现出显着降低解码精度时，两个声音相比，一个。解码是劣于动物的行为表现，因此表明存在替代编码策略。
How we distinguish multiple simultaneous stimuli is uncertain, particularly given that such stimuli sometimes recruit largely overlapping populations of neurons. One commonly proposed hypothesis is that the sharpness of tuning curves might change to limit the number of stimuli driving any given neuron when multiple stimuli are present. To test this hypothesis, we recorded the activity of neurons in the inferior colliculus while monkeys made saccades to either one or two simultaneous sounds differing in frequency and spatial location. Although monkeys easily distinguished simultaneous sounds (~90% correct performance), the frequency selectivity of inferior colliculus neurons on dual‐sound trials did not improve in any obvious way. Frequency selectivity was degraded on dual‐sound trials compared to single‐sound trials: neural response functions broadened and frequency accounted for less of the variance in firing rate. These changes in neural firing led a maximum‐likelihood decoder to perform worse on dual‐sound trials than on single‐sound trials. These results fail to support the hypothesis that changes in frequency response functions serve to reduce the overlap in the representation of simultaneous sounds. Instead, these results suggest that alternative possibilities, such as recent evidence of alternations in firing rate between the rates corresponding to each of the two stimuli, offer a more promising approach. How sensory representations encode multiple stimuli despite coarse coding is unknown. Using a maximum likelihood decoder operating on the spike count response patterns of monkey inferior colliculus neurons, we show a marked reduction in decoding accuracy when two sounds are presented compared to one. The decoding was inferior to the behavioural performance of the animals and thus suggests the presence of alternative coding strategies.
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