Department of Neurosurgery, National Neuroscience Institute, Singapore, Singapore.
Duke-NUS Medical School, Singapore, Singapore.
J Neural Eng. 2024 Aug 5;21(4). doi: 10.1088/1741-2552/ad618c.
Micro-electrocorticographic (ECoG) arrays are able to record neural activities from the cortical surface, without the need to penetrate the brain parenchyma. Owing in part to small electrode sizes, previous studies have demonstrated that single-unit spikes could be detected from the cortical surface, and likely from Layer I neurons of the neocortex. Here we tested the ability to useECoG arrays to decode, in rats, body position during open field navigation, through isolated single-unit activities.ECoG arrays were chronically implanted onto primary motor cortex (M1) of Wistar rats, and neural recording was performed in awake, behaving rats in an open-field enclosure. The signals were band-pass filtered between 300-3000 Hz. Threshold-crossing spikes were identified and sorted into distinct units based on defined criteria including waveform morphology and refractory period. Body positions were derived from video recordings. We used gradient-boosting machine to predict body position based on previous 100 ms of spike data, and correlation analyses to elucidate the relationship between position and spike patterns.Single-unit spikes could be extracted during chronic recording fromECoG, and spatial position could be decoded from these spikes with a mean absolute error of prediction of 0.135 and 0.090 in the x- and y- dimensions (of a normalized range from 0 to 1), and Pearson's r of 0.607 and 0.571, respectively.ECoG can detect single-unit activities that likely arise from superficial neurons in the cortex and is a promising alternative to intracortical arrays, with the added benefit of scalability to cover large cortical surface with minimal incremental risks. More studies should be performed in human related to its use as brain-machine interface.
微电极皮层电图 (ECoG) 阵列能够从皮层表面记录神经活动，而无需穿透脑实质。由于电极尺寸较小，先前的研究表明可以从皮层表面检测到单个单元的尖峰，并且可能来自新皮层的 I 层神经元。在这里，我们通过孤立的单个单元活动测试了使用 ECoG 阵列来解码大鼠在开阔场导航过程中体位的能力。ECoG 阵列被慢性植入 Wistar 大鼠的初级运动皮层 (M1)，并在开放场围场中对清醒、行为大鼠进行神经记录。信号在 300-3000 Hz 之间进行带通滤波。根据定义的标准（包括波形形态和不应期）识别和分类具有阈值交叉的尖峰到不同的单元。体位源自视频记录。我们使用梯度提升机根据前 100 ms 的尖峰数据预测体位，并进行相关分析以阐明位置与尖峰模式之间的关系。可以从 ECoG 的慢性记录中提取单个单元的尖峰，并且可以从这些尖峰解码空间位置，预测的 x 轴和 y 轴的平均绝对误差分别为 0.135 和 0.090（归一化范围为 0 到 1），Pearson r 分别为 0.607 和 0.571。ECoG 可以检测可能来自皮层浅层神经元的单个单元活动，是皮层内阵列的有前途的替代方案，其优势在于可扩展性，可以用最小的递增风险覆盖大面积的皮层。应该在人类中进行更多的研究，以研究其作为脑机接口的用途。
