Insanally Michele, Trumpis Michael, Wang Charles, Chiang Chia-Han, Woods Virginia, Palopoli-Trojani Kay, Bossi Silvia, Froemke Robert C, Viventi Jonathan
Skirball Institute for Biomolecular Medicine, Neuroscience Institute, Departments of Otolaryngology, Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA.
Center for Neural Science, New York University, New York, NY, USA.
J Neural Eng. 2016 Apr;13(2):026030-26030. doi: 10.1088/1741-2560/13/2/026030. Epub 2016 Mar 15.
Micro-electrocorticography (μECoG) offers a minimally invasive neural interface with high spatial resolution over large areas of cortex. However, electrode arrays with many contacts that are individually wired to external recording systems are cumbersome and make recordings in freely behaving rodents challenging. We report a novel high-density 60-electrode system for μECoG recording in freely moving rats.
Multiplexed headstages overcome the problem of wiring complexity by combining signals from many electrodes to a smaller number of connections. We have developed a low-cost, multiplexed recording system with 60 contacts at 406 μm spacing. We characterized the quality of the electrode signals using multiple metrics that tracked spatial variation, evoked-response detectability, and decoding value. Performance of the system was validated both in anesthetized animals and freely moving awake animals.
We recorded μECoG signals over the primary auditory cortex, measuring responses to acoustic stimuli across all channels. Single-trial responses had high signal-to-noise ratios (SNR) (up to 25 dB under anesthesia), and were used to rapidly measure network topography within ∼10 s by constructing all single-channel receptive fields in parallel. We characterized evoked potential amplitudes and spatial correlations across the array in the anesthetized and awake animals. Recording quality in awake animals was stable for at least 30 days. Finally, we used these responses to accurately decode auditory stimuli on single trials.
This study introduces (1) a μECoG recording system based on practical hardware design and (2) a rigorous analytical method for characterizing the signal characteristics of μECoG electrode arrays. This methodology can be applied to evaluate the fidelity and lifetime of any μECoG electrode array. Our μECoG-based recording system is accessible and will be useful for studies of perception and decision-making in rodents, particularly over the entire time course of behavioral training and learning.
微电极皮质电图（μECoG）提供了一种微创神经接口，可在大面积皮质上实现高空间分辨率。然而，具有许多单独连接到外部记录系统的触点的电极阵列很笨重，使得在自由活动的啮齿动物中进行记录具有挑战性。我们报告了一种用于在自由活动的大鼠中进行μECoG记录的新型高密度60电极系统。
多路复用前置放大器通过将来自多个电极的信号组合到较少数量的连接中来克服布线复杂性问题。我们开发了一种低成本的多路复用记录系统，其触点间距为406μm，共有60个触点。我们使用多种指标来表征电极信号的质量，这些指标跟踪空间变化、诱发反应可检测性和解码值。该系统的性能在麻醉动物和自由活动的清醒动物中均得到了验证。
我们在初级听觉皮质上记录了μECoG信号，测量了所有通道对听觉刺激的反应。单次试验反应具有高信噪比（SNR）（麻醉状态下高达25dB），并通过并行构建所有单通道感受野，在约10秒内快速测量网络地形图。我们表征了麻醉和清醒动物阵列上的诱发电位幅度和空间相关性。清醒动物的记录质量至少稳定30天。最后，我们利用这些反应在单次试验中准确解码听觉刺激。
本研究介绍了（1）一种基于实用硬件设计的μECoG记录系统，以及（2）一种用于表征μECoG电极阵列信号特征的严格分析方法。这种方法可用于评估任何μECoG电极阵列的保真度和寿命。我们基于μECoG的记录系统易于使用，将有助于啮齿动物感知和决策的研究，特别是在行为训练和学习的整个时间过程中。
