Suner Selim, Fellows Matthew R, Vargas-Irwin Carlos, Nakata Gordon Kenji, Donoghue John P
Department of Emergency Medicine and Surgery, Brown University, Providence, RI 02912, USA.
IEEE Trans Neural Syst Rehabil Eng. 2005 Dec;13(4):524-41. doi: 10.1109/TNSRE.2005.857687.
Multiple-electrode arrays are valuable both as a research tool and as a sensor for neuromotor prosthetic devices, which could potentially restore voluntary motion and functional independence to paralyzed humans. Long-term array reliability is an important requirement for these applications. Here, we demonstrate the reliability of a regular array of 100 microelectrodes to obtain neural recordings from primary motor cortex (MI) of monkeys for at least three months and up to 1.5 years. We implanted Bionic (Cyberkinetics, Inc., Foxboro, MA) silicon probe arrays in MI of three Macaque monkeys. Neural signals were recorded during performance of an eight-direction, push-button task. Recording reliability was evaluated for 18, 35, or 51 sessions distributed over 83, 179, and 569 days after implantation, respectively, using qualitative and quantitative measures. A four-point signal quality scale was defined based on the waveform amplitude relative to noise. A single observer applied this scale to score signal quality for each electrode. A mean of 120 (+/- 17.6 SD), 146 (+/- 7.3), and 119 (+/- 16.9) neural-like waveforms were observed from 65-85 electrodes across subjects for all recording sessions of which over 80% were of high quality. Quantitative measures demonstrated that waveforms had signal-to-noise ratio (SNR) up to 20 with maximum peak-to-peak amplitude of over 1200 microv with a mean SNR of 4.8 for signals ranked as high quality. Mean signal quality did not change over the duration of the evaluation period (slope 0.001, 0.0068 and 0.03; NS). By contrast, neural waveform shape varied between, but not within days in all animals, suggesting a shifting population of recorded neurons over time. Arm-movement related modulation was common and 66% of all recorded neurons were tuned to reach direction. The ability for the array to record neural signals from parietal cortex was also established. These results demonstrate that neural recordings that can provide movement related signals for neural prostheses, as well as for fundamental research applications, can be reliably obtained for long time periods using a monolithic microelectrode array in primate MI and potentially from other cortical areas as well.
多电极阵列作为一种研究工具以及神经运动假体装置的传感器都很有价值，这种装置有可能恢复瘫痪患者的自主运动和功能独立性。长期阵列可靠性是这些应用的一项重要要求。在此，我们展示了一个由100个微电极组成的规则阵列的可靠性，该阵列从猴子的初级运动皮层（MI）获取神经记录至少三个月，最长达1.5年。我们将仿生（Cyberkinetics公司，马萨诸塞州福克斯伯勒）硅探针阵列植入三只猕猴的MI。在执行一个八方向按钮任务期间记录神经信号。分别在植入后83、179和569天分布的18、35或51次记录时段中，使用定性和定量方法评估记录可靠性。基于相对于噪声的波形幅度定义了一个四点信号质量量表。由一名观察者应用该量表对每个电极的信号质量进行评分。在所有记录时段中，从各受试者的65 - 85个电极观察到平均120（±17.6标准差）、146（±7.3）和119（±16.9）个类神经波形，其中超过80%为高质量波形。定量测量表明，波形的信噪比（SNR）高达20，最大峰 - 峰幅度超过1200微伏，对于评为高质量的信号，平均信噪比为4.8。在评估期内平均信号质量没有变化（斜率分别为0.001、0.0068和0.03；无显著性差异）。相比之下，神经波形形状在所有动物的不同天数之间有所变化，但在同一天内没有变化，这表明随着时间推移，记录的神经元群体在发生变化。与手臂运动相关的调制很常见，所有记录的神经元中有66%被调整到与到达方向相关。该阵列从顶叶皮层记录神经信号的能力也得到了证实。这些结果表明，使用灵长类动物MI中的单片微电极阵列，以及潜在地从其他皮层区域，能够长时间可靠地获取可为神经假体以及基础研究应用提供与运动相关信号的神经记录。
