Department of Developmental Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan.
PLoS One. 2012;7(10):e47749. doi: 10.1371/journal.pone.0047749. Epub 2012 Oct 24.
Various peripheral receptors provide information concerning position and movement to the central nervous system to achieve complex and dexterous movements of forelimbs in primates. The response properties of single afferent receptors to movements at a single joint have been examined in detail, but the population coding of peripheral afferents remains poorly defined. In this study, we obtained multichannel recordings from dorsal root ganglion (DRG) neurons in cervical segments of monkeys. We applied the sparse linear regression (SLiR) algorithm to the recordings, which selects useful input signals to reconstruct movement kinematics. Multichannel recordings of peripheral afferents were performed by inserting multi-electrode arrays into the DRGs of lower cervical segments in two anesthetized monkeys. A total of 112 and 92 units were responsive to the passive joint movements or the skin stimulation with a painting brush in Monkey 1 and Monkey 2, respectively. Using the SLiR algorithm, we reconstructed the temporal changes of joint angle, angular velocity, and acceleration at the elbow, wrist, and finger joints from temporal firing patterns of the DRG neurons. By automatically selecting a subset of recorded units, the SLiR achieved superior generalization performance compared with a regularized linear regression algorithm. The SLiR selected not only putative muscle units that were responsive to only the passive movements, but also a number of putative cutaneous units responsive to the skin stimulation. These results suggested that an ensemble of peripheral primary afferents that contains both putative muscle and cutaneous units encode forelimb joint kinematics of non-human primates.
各种外周受体为中枢神经系统提供有关位置和运动的信息，以实现灵长类动物前肢的复杂和灵巧运动。单个传入受体对单个关节运动的反应特性已经得到了详细研究，但外周传入的群体编码仍未得到明确界定。在这项研究中，我们从猴子颈椎段的背根神经节（DRG）神经元中获得了多通道记录。我们将稀疏线性回归（SLiR）算法应用于记录中，该算法选择有用的输入信号来重建运动运动学。通过将多电极阵列插入到两只麻醉猴子的下颈椎段的 DRG 中，我们对周围传入神经进行了多通道记录。在 Monkey 1 和 Monkey 2 中，共有 112 和 92 个单位对被动关节运动或用画笔进行的皮肤刺激有反应。使用 SLiR 算法，我们从 DRG 神经元的时间发射模式重建了肘部、手腕和手指关节的关节角度、角速度和加速度的时间变化。通过自动选择记录单元的子集，SLiR 与正则化线性回归算法相比实现了更好的泛化性能。SLiR 不仅选择了仅对被动运动有反应的假定肌肉单元，还选择了许多对皮肤刺激有反应的假定皮肤单元。这些结果表明，包含假定肌肉和皮肤单元的外周初级传入神经的集合编码了非人类灵长类动物的前肢关节运动学。
