Neuromodulatory Mechanisms Underlying Contrast Gain Control in Mouse Auditory Cortex
Neuromodulatory Mechanisms Underlying Contrast Gain Control in Mouse Auditory Cortex
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DOI：
10.1523/jneurosci.2054-21.2022
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发表时间：
2022-07-13
影响因子：
5.3
通讯作者：
Tzounopoulos, Thanos
中科院分区：
文献类型：
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作者：
Cody, Patrick A.;Tzounopoulos, Thanos
神经适应使大脑能够有效地处理感觉信号，尽管背景噪声有很大的变化。以前的研究已经确定，最近的背景光谱或时空统计尺度神经反应的感官刺激通过一个典型的归一化计算，这是保守的物种和感觉域。在听觉通路中，一种主要形式的正常化，称为对比度增益控制，表现为降低瞬时放电率增益，神经输入-输出关系的斜率，随着时间和频率的背景声级（对比度）的可变性增加。尽管这种增益重新标度，听觉皮层的平均放电率变得不受声级对比度的影响，称为对比度不变性。这两种现象的潜在神经调节机制仍然未知。为了在雄性和雌性小鼠中研究这些机制，我们在初级听觉皮层（A1）的第2/3层神经元中使用了双光子钙成像制剂，沿着药理学和遗传学KO方法。我们发现，神经调节皮层突触锌信号是必要的对比度增益控制，但不是对比度不变性在小鼠A1。
Neural adaptation enables the brain to efficiently process sensory signals despite large changes in background noise. Previous studies have established that recent background spectro- or spatio-temporal statistics scale neural responses to sensory stimuli via a canonical normalization computation, which is conserved among species and sensory domains. In the auditory pathway, one major form of normalization, termed contrast gain control, presents as decreasing instantaneous firing-rate gain, the slope of the neural input-output relationship, with increasing variability of background sound levels (contrast) across time and frequency. Despite this gain rescaling, mean firing-rates in auditory cortex become invariant to sound level contrast, termed contrast invariance. The underlying neuromodulatory mechanisms of these two phenomena remain unknown. To study these mechanisms in male and female mice, we used a 2-photon calcium imaging preparation in layer 2/3 neurons of primary auditory cortex (A1), along with pharmacological and genetic KO approaches. We found that neuromodulatory cortical synaptic zinc signaling is necessary for contrast gain control but not contrast invariance in mouse A1.