Committee on Computational Neuroscience, University of Chicago, Chicago, Illinois 60637, USA.
J Neurosci. 2010 Dec 15;30(50):17079-90. doi: 10.1523/JNEUROSCI.2558-10.2010.
Few studies have investigated how the cortex encodes the preshaping of the hand as an object is grasped, an ethological movement referred to as prehension. We developed an encoding model of hand kinematics to test whether primary motor cortex (MI) neurons encode temporally extensive combinations of joint motions that characterize a prehensile movement. Two female rhesus macaque monkeys were trained to grasp 4 different objects presented by a robot while their arm was held in place by a thermoplastic brace. We used multielectrode arrays to record MI neurons and an infrared camera motion tracking system to record the 3-D positions of 14 markers placed on the monkeys' wrist and digits. A generalized linear model framework was used to predict the firing rate of each neuron in a 4 ms time interval, based on its own spiking history and the spatiotemporal kinematics of the joint angles of the hand. Our results show that the variability of the firing rate of MI neurons is better described by temporally extensive combinations of finger and wrist joint angle kinematics rather than any individual joint motion or any combination of static kinematic parameters at their optimal lag. Moreover, a higher percentage of neurons encoded joint angular velocities than joint angular positions. These results suggest that neurons encode the covarying trajectories of the hand's joints during a prehensile movement.
很少有研究调查大脑皮层如何对手部的预塑形进行编码，这种预塑形是一种被称为抓握的行为运动。我们开发了一种手部运动学的编码模型，以测试初级运动皮层（MI）神经元是否编码了特征性抓握运动的关节运动的时间广泛组合。两只雌性恒河猴被训练用机器人抓取 4 种不同的物体，同时它们的手臂被热塑性支架固定在适当位置。我们使用多电极阵列记录 MI 神经元，并使用红外摄像机运动跟踪系统记录放置在猴子手腕和手指上的 14 个标记的 3D 位置。基于神经元自身的放电历史和手部关节角度的时空运动学，我们使用广义线性模型框架来预测每个神经元在 4 毫秒时间间隔内的放电率。我们的结果表明，MI 神经元的放电率的可变性可以通过手指和手腕关节角度运动学的时间广泛组合来更好地描述，而不是任何单个关节运动或其最佳滞后时的静态运动学参数的任何组合。此外，更多的神经元编码关节角速度而不是关节角度位置。这些结果表明，神经元在抓握运动期间编码手关节的协变轨迹。
