Wide-dynamic-range forward suppression in marmoset inferior colliculus neurons is generated centrally and accounts for perceptual masking.
Wide-dynamic-range forward suppression in marmoset inferior colliculus neurons is generated centrally and accounts for perceptual masking.
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DOI：
10.1523/jneurosci.5359-08.2009
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发表时间：
2009-02-25
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影响因子：
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通讯作者：
Young ED
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文献类型：
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作者：
Nelson PC;Smith ZM;Young ED
一个有机体的能力，以检测和区分感官输入取决于最近的刺激历史。例如，在掩蔽刺激之后，简短音调的感知检测阈值可以提高多达50 dB。以前的工作表明，这种前掩蔽不是外周神经适应的直接结果;中央通路显然以进一步减弱输入对短探针信号的响应的方式修改了表示。在这里，我们表明，这种转换是由下丘（IC）的水平完成。单神经元细胞外反应记录在清醒的绒猴IC的中央核。在最佳频率下呈现的20 ms探测音的阈值是针对各种掩蔽探测延迟在掩蔽SPL和频率范围内确定的。数据中最引人注目的方面是随着SPL的增加，前掩蔽物的效力增加，尽管事实上对掩蔽物的兴奋性反应在相同的水平范围内通常是饱和的或非单调的。这导致在高掩蔽水平下的探测阈值几乎总是高于在听神经中观察到的阈值。探测阈值的变化通常不会引起持续的兴奋性反应的掩蔽，相反，我们提出了一个广泛的动态范围的抑制机制锁定到声音偏移作为几个关键方面的数据的解释。这些研究结果进一步描绘的作用，皮层下的听觉处理中产生的上下文相关的表示正在进行的声学场景。
An organism’s ability to detect and discriminate sensory inputs depends on the recent stimulus history. For example, perceptual detection thresholds for a brief tone can be elevated by as much as 50 dB when following a masking stimulus. Previous work suggests that such forward masking is not a direct result of peripheral neural adaptation; the central pathway apparently modifies the representation in a way that further attenuates the input’s response to short probe signals. Here, we show that much of this transformation is complete by the level of the inferior colliculus (IC). Single-neuron extracellular responses were recorded in the central nucleus of the awake marmoset IC. The threshold for a 20-ms probe tone presented at best frequency was determined for various masker-probe delays, over a range of masker SPLs and frequencies. The most striking aspect of the data was the increased potency of forward maskers as their SPL was increased, despite the fact that the excitatory response to the masker was often saturating or non-monotonic over the same range of levels. This led to probe thresholds at high masker levels that were almost always higher than those observed in the auditory nerve. Probe threshold shifts were not usually caused by a persistent excitatory response to the masker; instead we propose a wide dynamic-range inhibitory mechanism locked to sound offset as an explanation for several key aspects of the data. These findings further delineate the role of subcortical auditory processing in the generation of a context-dependent representation of ongoing acoustic scenes.