Cecchetto Claudia, Vassanelli Stefano, Kuhn Bernd
Department of Biomedical Sciences, Section of Physiology, University of Padua, Padua, Italy.
Optical Neuroimaging Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
Front Neurosci. 2021 Nov 11;15:741279. doi: 10.3389/fnins.2021.741279. eCollection 2021.
Neuronal population activity, both spontaneous and sensory-evoked, generates propagating waves in cortex. However, high spatiotemporal-resolution mapping of these waves is difficult as calcium imaging, the work horse of current imaging, does not reveal subthreshold activity. Here, we present a platform combining voltage or calcium two-photon imaging with multi-channel local field potential (LFP) recordings in different layers of the barrel cortex from anesthetized and awake head-restrained mice. A chronic cranial window with access port allows injecting a viral vector expressing GCaMP6f or the voltage-sensitive dye (VSD) ANNINE-6plus, as well as entering the brain with a multi-channel neural probe. We present both average spontaneous activity and average evoked signals in response to multi-whisker air-puff stimulations. Time domain analysis shows the dependence of the evoked responses on the cortical layer and on the state of the animal, here separated into anesthetized, awake but resting, and running. The simultaneous data acquisition allows to compare the average membrane depolarization measured with ANNINE-6plus with the amplitude and shape of the LFP recordings. The calcium imaging data connects these data sets to the large existing database of this important second messenger. Interestingly, in the calcium imaging data, we found a few cells which showed a decrease in calcium concentration in response to vibrissa stimulation in awake mice. This system offers a multimodal technique to study the spatiotemporal dynamics of neuronal signals through a 3D architecture . It will provide novel insights on sensory coding, closing the gap between electrical and optical recordings.
神经元群体活动，包括自发活动和感觉诱发活动，会在皮层中产生传播波。然而，由于钙成像（当前成像的主要手段）无法揭示阈下活动，对这些波进行高时空分辨率映射很困难。在此，我们展示了一个平台，该平台将电压或钙双光子成像与来自麻醉和清醒头部固定小鼠桶状皮层不同层的多通道局部场电位（LFP）记录相结合。带有接入端口的慢性颅骨窗口允许注射表达GCaMP6f的病毒载体或电压敏感染料（VSD）ANNINE-6plus，以及通过多通道神经探针进入大脑。我们展示了对多根触须吹气刺激的平均自发活动和平均诱发信号。时域分析显示诱发反应对皮层层和动物状态的依赖性，这里将动物状态分为麻醉、清醒但休息和奔跑。同步数据采集允许将用ANNINE-6plus测量的平均膜去极化与LFP记录的幅度和形状进行比较。钙成像数据将这些数据集与这个重要第二信使的大量现有数据库联系起来。有趣的是，在钙成像数据中，我们发现一些细胞在清醒小鼠对触须刺激的反应中钙浓度降低。该系统提供了一种多模态技术，通过三维结构研究神经元信号的时空动态。它将为感觉编码提供新的见解，弥合电记录和光记录之间的差距。
