Turner R S, Anderson M E
Department of Physiology and Biophysics, University of Washington, Seattle 98195, USA.
J Neurophysiol. 1997 Mar;77(3):1051-74. doi: 10.1152/jn.1997.77.3.1051.
Movement-related discharge of neurons in the internal and external segments of the globus pallidus (GPi and GPe, respectively) of two monkeys was studied during reaching movements in a two-dimensional work-space. Discharge was studied during movements to targets in eight directions and at three distances from the starting position under three behavioral conditions that manipulated target visibility and movement triggering. A total of 73 neurons (57 in GPe and 18 in GPi) with changes in discharge in concert with arm movements were included in a quantitative analysis. Of these, 83% also changed their discharge during manipulation of the contralateral arm outside of the task. Although 73% of changes in discharge began before the initiation of movement, they seldom preceded the initial activity of the antagonist muscles. Decreases in discharge were more common than reported previously, constituting 40% of the changes in discharge detected. In GPi neurons, decreases also tended to begin earlier than increases. Changes in discharge in GPe neurons were of larger magnitude than those in GPi, and increases in discharge were larger than decreases. Onsets of changes in discharge were temporally linked to movement onset in 69% of neurons. Time locking of neural onset to trigger presentation and movement termination was found in only 30 and 1% of neurons, respectively. Direction of movement influenced the magnitude of changes in discharge in 78% of cells. Directional modulations were broadly tuned and preferred directions were uniformly distributed across the range of directions. When directional modulations were large, preferred directions were consistent for different amplitudes of movement and for different behavioral conditions. Amplitude of movement influenced the magnitude of changes in discharge in 78% of cells, and in 80% of cases that relation had a significant linear component. Amplitude effects were not more common or stronger for movements in directions close to a cell's preferred direction. Linear relations to movement amplitude were more common and accounted for more of the trial-to-trial variance in discharge rate than relations to either average velocity or movement duration. The relation to movement amplitude was consistent for two behavioral conditions when the change in discharge was scaled strongly with movement amplitude. Movement-related changes in discharge of neurons in the skeletomotor portions of both pallidal segments reflect the kinematics of movement. This information, encoded in combination with sensory and contextual information, may play an on-line role in the selective facilitation and suppression of different frontal thalamocortical circuits.
在二维工作空间的伸手动作过程中，研究了两只猴子苍白球内侧段和外侧段（分别为GPi和GPe）中与运动相关的神经元放电情况。在三种行为条件下，研究了向八个方向的目标移动以及在距起始位置三个距离处移动时的放电情况，这三种行为条件分别控制目标可见性和运动触发。共有73个神经元（GPe中57个，GPi中18个）的放电随手臂运动而变化，被纳入定量分析。其中，83%的神经元在任务之外对侧手臂的操作过程中也改变了放电。虽然73%的放电变化在运动开始前就已开始，但它们很少先于拮抗肌的初始活动。放电减少比之前报道的更为常见，占检测到的放电变化的40%。在GPi神经元中，放电减少也往往比增加开始得更早。GPe神经元的放电变化幅度大于GPi神经元，且放电增加大于放电减少。69%的神经元放电变化的起始时间与运动起始在时间上相关。分别只有30%和1%的神经元的神经起始与触发呈现和运动终止存在时间锁定。78%的细胞中，运动方向影响放电变化的幅度。方向调制的范围较广，偏好方向在整个方向范围内均匀分布。当方向调制较大时，不同运动幅度和不同行为条件下的偏好方向是一致的。78%的细胞中，运动幅度影响放电变化的幅度，在80%的情况下，这种关系具有显著的线性成分。对于接近细胞偏好方向的运动，幅度效应并不更常见或更强。与运动幅度的线性关系比与平均速度或运动持续时间的关系更常见，并且在放电率的逐次试验方差中占比更大。当放电变化与运动幅度密切相关时，在两种行为条件下，与运动幅度的关系是一致的。苍白球两个节段的骨骼运动部分中神经元的运动相关放电变化反映了运动的运动学特征。这些信息与感觉和情境信息相结合进行编码，可能在不同额叶丘脑皮质回路的选择性促进和抑制中发挥在线作用。
