Abstract：
Human neuronal activity, recorded in vivo from microelectrodes, may offer valuable insights into physiological mechanisms underlying human cognition and pathophysiological mechanisms of brain diseases, in particular epilepsy. Continuous and long-term recordings are necessary to monitor non predictable pathological and physiological activities like seizures or sleep. Because of their high impedance, microelectrodes are more sensitive to noise than macroelectrodes. Low noise levels are crucial to detect action potentials from background noise, and to further isolate single neuron activities. Therefore, long-term recordings of multi-unit activity remains a challenge. We shared here our experience with microelectrode recordings and our efforts to reduce noise levels in order to improve signal quality. We also provided detailed technical guidelines for the connection, recording, imaging and signal analysis of microelectrode recordings.
During the last 10 years, we implanted 122 bundles of Behnke-Fried hybrid macro-microelectrodes, in 56 patients with pharmacoresistant focal epilepsy. Microbundles were implanted in the temporal lobe (74%), as well as frontal (15%), parietal (6%) and occipital (5%) lobes. Low noise levels depended on our technical setup. The noise reduction was mainly obtained after electrical insulation of the patient\'s recording room and the use of a reinforced microelectrode model, reaching median root mean square values of 5.8 µV. Seventy percent of the bundles could record multi-units activities (MUA), on around 3 out of 8 wires per bundle and for an average of 12 days. Seizures were recorded by microelectrodes in 91% of patients, when recorded continuously, and MUA were recorded during seizures for 75 % of the patients after the insulation of the room. Technical guidelines are proposed for (i) electrode tails manipulation and protection during surgical bandage and connection to both clinical and research amplifiers, (ii) electrical insulation of the patient\'s recording room and shielding, (iii) data acquisition and storage, and (iv) single-units activities analysis.
We progressively improved our recording setup and are now able to record (i) microelectrode signals with low noise level up to 3 weeks duration, and (ii) MUA from an increased number of wires . We built a step by step procedure from electrode trajectory planning to recordings. All these delicate steps are essential for continuous long-term recording of units in order to advance in our understanding of both the pathophysiology of ictogenesis and the neuronal coding of cognitive and physiological functions.
During the last 10 years, we implanted 122 bundles of Behnke-Fried hybrid macro-microelectrodes, in 56 patients with pharmacoresistant focal epilepsy. Microbundles were implanted in the temporal lobe (74%), as well as frontal (15%), parietal (6%) and occipital (5%) lobes. Low noise levels depended on our technical setup. The noise reduction was mainly obtained after electrical insulation of the patient\'s recording room and the use of a reinforced microelectrode model, reaching median root mean square values of 5.8 µV. Seventy percent of the bundles could record multi-units activities (MUA), on around 3 out of 8 wires per bundle and for an average of 12 days. Seizures were recorded by microelectrodes in 91% of patients, when recorded continuously, and MUA were recorded during seizures for 75 % of the patients after the insulation of the room. Technical guidelines are proposed for (i) electrode tails manipulation and protection during surgical bandage and connection to both clinical and research amplifiers, (ii) electrical insulation of the patient\'s recording room and shielding, (iii) data acquisition and storage, and (iv) single-units activities analysis.
We progressively improved our recording setup and are now able to record (i) microelectrode signals with low noise level up to 3 weeks duration, and (ii) MUA from an increased number of wires . We built a step by step procedure from electrode trajectory planning to recordings. All these delicate steps are essential for continuous long-term recording of units in order to advance in our understanding of both the pathophysiology of ictogenesis and the neuronal coding of cognitive and physiological functions.
摘要：
人类神经元活动，从微电极体内记录，可以为人类认知的生理机制和脑部疾病的病理生理机制提供有价值的见解，特别是癫痫。连续和长期的记录是必要的，以监测不可预测的病理和生理活动，如癫痫发作或睡眠。由于它们的高阻抗，微电极比宏电极对噪声更敏感。低噪声水平对于从背景噪声中检测动作电位至关重要，并进一步隔离单个神经元的活动。因此,多单位活动的长期记录仍然是一个挑战。我们在这里分享了我们在微电极记录方面的经验，以及我们为降低噪声水平以提高信号质量所做的努力。我们还提供了详细的连接技术指南，录音,微电极记录的成像和信号分析。
在过去的10年里,我们植入了122束Behnke-Fried混合宏微电极，56例药物耐药局灶性癫痫患者。微束植入颞叶（74%），以及额叶（15%），顶叶（6％）和枕叶（5％）。低噪声水平取决于我们的技术设置。降噪主要是在患者的录音室电绝缘和使用增强的微电极模型后获得的，达到5.8µV的中值均方根值。70%的捆绑包可以记录多单位活动(MUA)，每束8根线中大约有3根，平均12天。91％的患者通过微电极记录癫痫发作，当连续记录时，在房间保温后，有75％的患者在癫痫发作期间记录了MUA。提出了技术准则，用于（i）手术绷带和连接到临床和研究放大器期间的电极尾巴操纵和保护，(ii)病人记录室的电绝缘和屏蔽，(iii)数据采集和存储，和(四)单一单位活动分析。
我们逐步改进了我们的记录设置，现在能够以低噪声水平记录（i）微电极信号，持续时间长达3周，和(ii)来自增加数量的导线的MUA。我们建立了从电极轨迹规划到记录的逐步程序。所有这些微妙的步骤对于连续长期记录单位至关重要，以促进我们对发生的病理生理学以及认知和生理功能的神经元编码的理解。
在过去的10年里,我们植入了122束Behnke-Fried混合宏微电极，56例药物耐药局灶性癫痫患者。微束植入颞叶（74%），以及额叶（15%），顶叶（6％）和枕叶（5％）。低噪声水平取决于我们的技术设置。降噪主要是在患者的录音室电绝缘和使用增强的微电极模型后获得的，达到5.8µV的中值均方根值。70%的捆绑包可以记录多单位活动(MUA)，每束8根线中大约有3根，平均12天。91％的患者通过微电极记录癫痫发作，当连续记录时，在房间保温后，有75％的患者在癫痫发作期间记录了MUA。提出了技术准则，用于（i）手术绷带和连接到临床和研究放大器期间的电极尾巴操纵和保护，(ii)病人记录室的电绝缘和屏蔽，(iii)数据采集和存储，和(四)单一单位活动分析。
我们逐步改进了我们的记录设置，现在能够以低噪声水平记录（i）微电极信号，持续时间长达3周，和(ii)来自增加数量的导线的MUA。我们建立了从电极轨迹规划到记录的逐步程序。所有这些微妙的步骤对于连续长期记录单位至关重要，以促进我们对发生的病理生理学以及认知和生理功能的神经元编码的理解。
