Suppression of cortical neural variability is stimulus- and state-dependent.
Suppression of cortical neural variability is stimulus- and state-dependent.
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DOI：
10.1152/jn.00723.2011
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发表时间：
2012-11
影响因子：
2.5
通讯作者：
Ben White;L. Abbott;J. Fiser
中科院分区：
文献类型：
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作者：
Ben White;L. Abbott;J. Fiser
内部产生的自发活动在皮层中无处不在，但它似乎对感觉处理没有显着的负面影响。各种研究已经发现，刺激开始减少皮层反应的变异性，但这种抑制的特点仍然没有探索。通过记录清醒和麻醉大鼠的多单位活动，我们研究了这种噪声抑制是否以及如何依赖于刺激的性质和皮层的状态。与理论预测一致，我们发现，在清醒的大鼠的噪声抑制的程度有一个非单调依赖于闪烁的视觉刺激的时间频率与噪声抑制的最佳频率~2 Hz。这种效应不能用自发神经活动的功率谱特征来解释。变异性抑制的非单调频率依赖性在麻醉水平增加的情况下逐渐消失，并转变为随频率降低而增加抑制的单调模式。信号噪声比显示出类似的，虽然反转，依赖于皮质状态和频率。这些结果表明，在清醒的皮层系统，调谐支持信号传播和编码的主动噪声抑制机制的存在。
Internally generated, spontaneous activity is ubiquitous in the cortex, yet it does not appear to have a significant negative impact on sensory processing. Various studies have found that stimulus onset reduces the variability of cortical responses, but the characteristics of this suppression remained unexplored. By recording multiunit activity from awake and anesthetized rats, we investigated whether and how this noise suppression depends on properties of the stimulus and on the state of the cortex. In agreement with theoretical predictions, we found that the degree of noise suppression in awake rats has a nonmonotonic dependence on the temporal frequency of a flickering visual stimulus with an optimal frequency for noise suppression ~2 Hz. This effect cannot be explained by features of the power spectrum of the spontaneous neural activity. The nonmonotonic frequency dependence of the suppression of variability gradually disappears under increasing levels of anesthesia and shifts to a monotonic pattern of increasing suppression with decreasing frequency. Signal-to-noise ratios show a similar, although inverted, dependence on cortical state and frequency. These results suggest the existence of an active noise suppression mechanism in the awake cortical system that is tuned to support signal propagation and coding.