Neurons communicate through electrochemical signaling within a complex network. These signals are composed of changes in membrane potentials and are traditionally measured with the aid of (toxic) fluorescent labels or invasive electrical probes. Here, we demonstrate an improvement in label-free second harmonic neuroimaging sensitivity by ~3 orders of magnitude using a wide-field medium repetition rate illumination. We perform a side-by-side patch-clamp and second harmonic imaging comparison to demonstrate the theoretically predicted linear correlation between whole neuron membrane potential changes and the square root of the second harmonic intensity. We assign the ion induced changes to the second harmonic intensity to changes in the orientation of membrane interfacial water, which is used to image spatiotemporal changes in the membrane potential and K⁺ ion flux. We observe a non-uniform spatial distribution and temporal activity of ion channels in mouse brain neurons.

中文翻译：

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膜水用于在单​​个细胞水平上探测神经元膜电位和离子通量。

神经元通过复杂网络内的电化学信号进行通信。这些信号由膜电位的变化组成，传统上是借助（有毒的）荧光标记或侵入性电探针进行测量的。在这里，我们证明了使用广域中等重复率照明，无标记的二次谐波神经影像敏感性提高了约3个数量级。我们进行并排膜片钳和二次谐波成像比较，以证明理论上预测的整个神经元膜电位变化与二次谐波强度的平方根之间的线性相关性。我们将离子诱导的变化分配给二次谐波强度，以改变膜界面水的方向，⁺离子通量。我们观察到小鼠脑神经元中离子通道的非均匀空间分布和时间活动。