Graduate School of Science and Technology, Keio University, Kanagawa, Japan. Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Saitama, Japan. Department of Neurophysiology, National Institute of Neuroscience, Tokyo, Japan.
J Neural Eng. 2018 Jun;15(3):036019. doi: 10.1088/1741-2552/aab307. Epub 2018 Mar 1.
Motor map has been widely used as an indicator of motor skills and learning, cortical injury, plasticity, and functional recovery. Cortical stimulation mapping using epidural electrodes is recently adopted for animal studies. However, several technical limitations still remain. Test-retest reliability of epidural cortical stimulation (ECS) mapping has not been examined in detail. Many previous studies defined evoked movements and motor thresholds by visual inspection, and thus, lacked quantitative measurements. A reliable and quantitative motor map is important to elucidate the mechanisms of motor cortical reorganization. The objective of the current study was to perform reliable ECS mapping of motor representations based on the motor thresholds, which were stochastically estimated by motor evoked potentials and chronically implanted micro-electrocorticographical (µECoG) electrode arrays, in common marmosets.
ECS was applied using the implanted µECoG electrode arrays in three adult common marmosets under awake conditions. Motor evoked potentials were recorded through electromyographical electrodes implanted in upper limb muscles. The motor threshold was calculated through a modified maximum likelihood threshold-hunting algorithm fitted with the recorded data from marmosets. Further, a computer simulation confirmed reliability of the algorithm.
Computer simulation suggested that the modified maximum likelihood threshold-hunting algorithm enabled to estimate motor threshold with acceptable precision. In vivo ECS mapping showed high test-retest reliability with respect to the excitability and location of the cortical forelimb motor representations.
Using implanted µECoG electrode arrays and a modified motor threshold-hunting algorithm, we were able to achieve reliable motor mapping in common marmosets with the ECS system.
运动图被广泛用作运动技能和学习、皮质损伤、可塑性和功能恢复的指标。最近，采用硬膜外电极对动物进行皮质刺激映射。然而，仍存在一些技术限制。硬膜外皮质刺激（ECS）映射的测试-再测试可靠性尚未详细检查。许多以前的研究通过视觉检查定义了诱发电位和运动阈值，因此缺乏定量测量。可靠和定量的运动图对于阐明运动皮质重组的机制非常重要。本研究的目的是基于运动诱发电位和慢性植入微电皮质图（µECoG）电极阵列随机估计的运动阈值，对普通狨猴进行可靠的 ECS 运动图绘制。
在清醒状态下，使用植入的µECoG 电极阵列在三只成年普通狨猴中进行 ECS。通过植入上肢肌肉的肌电图电极记录运动诱发电位。通过与记录的狨猴数据拟合的修改后的最大似然阈值搜索算法计算运动阈值。此外，计算机模拟证实了该算法的可靠性。
计算机模拟表明，修改后的最大似然阈值搜索算法能够以可接受的精度估计运动阈值。体内 ECS 映射显示出与皮质前肢运动代表的兴奋性和位置有关的高度测试-再测试可靠性。
使用植入的µECoG 电极阵列和修改后的运动阈值搜索算法，我们能够在 ECS 系统中实现普通狨猴的可靠运动映射。
