Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
Laboratory of Neuroenergetics and cellular dynamics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
Nat Commun. 2018 Dec 11;9(1):5287. doi: 10.1038/s41467-018-07713-w.
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.
神经元在复杂的网络中通过电化学信号进行通讯。这些信号由膜电位的变化组成，传统上借助（有毒的）荧光标记物或侵入性的电探针进行测量。在这里，我们通过使用宽场中重复率照明，将无标记的二次谐波神经成像灵敏度提高了约 3 个数量级。我们进行了旁贴式膜片钳和二次谐波成像的对比，以证明整个神经元膜电位变化与二次谐波强度的平方根之间存在理论预测的线性相关性。我们将离子诱导的变化归因于膜界面水分子的取向变化，这可用于成像膜电位和 K 离子通量的时空变化。我们观察到在小鼠脑神经元中离子通道的空间分布和时间活动不均匀。
