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首页> 外文期刊>Journal of Neurophysiology >Visuomotor processing as reflected in the directional discharge of premotor and primary motor cortex neurons.
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Visuomotor processing as reflected in the directional discharge of premotor and primary motor cortex neurons.

机译：运动前和初级运动皮层神经元的定向放电所反映的运动运动过程。

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摘要

Premotor and primary motor cortical neuronal firing was studied in two monkeys during an instructed delay, pursuit tracking task. The task included a premovement "cue period," during which the target was presented at the periphery of the workspace and moved to the center of the workspace along one of eight directions at one of four constant speeds. The "track period" consisted of a visually guided, error-constrained arm movement during which the animal tracked the target as it moved from the central start box along a line to the opposite periphery of the workspace. Behaviorally, the animals tracked the required directions and speeds with highly constrained trajectories. The eye movements consisted of saccades to the target at the onset of the cue period, followed by smooth pursuit intermingled with saccades throughout the cue and track periods. Initially, an analysis of variance (ANOVA) was used to test for direction and period effects in the firing. Subsequently, a linear regression analysis was used to fit the average firing from the cue and track periods to a cosine model. Directional tuning as determined by a significant fit to the cosine model was a prominent feature of the discharge during both the cue and track periods. However, the directional tuning of the firing of a single cell was not always constant across the cue and track periods. Approximately one-half of the neurons had differences in their preferred directions (PDs) of >45 degrees between cue and track periods. The PD in the cue or track period was not dependent on the target speed. A second linear regression analysis based on calculation of the preferred direction in 20-ms bins (i.e., the PD trajectory) was used to examine on a finer time scale the temporal evolution of this change in directional tuning. The PD trajectories in the cue period were not straight but instead rotated over the workspace to align with the track period PD. Both clockwise and counterclockwise rotations occurred. The PD trajectories were relatively straight during most of the track period. The rotation and eventual convergence of the PD trajectories in the cue period to the preferred direction of the track period may reflect the transformation of visual information into motor commands. The widely dispersed PD trajectories in the cue period would allow targets to be detected over a wide spatial aperture. The convergence of the PD trajectories occurring at the cue-track transition may serve as a "Go" signal to move that was not explicitly supplied by the paradigm. Furthermore, the rotation and convergence of the PD trajectories may provide a mechanism for nonstandard mapping. Standard mapping refers to a sensorimotor transformation in which the stimulus is the object of the reach. Nonstandard mapping is the mapping of an arbitrary stimulus into an arbitrary movement. The shifts in the PD may allow relevant visual information from any direction to be transformed into an appropriate movement direction, providing a neural substrate for nonstandard stimulus-response mappings.
机译：在指令的延迟，追踪追踪任务中，对两只猴子的运动前和原运动皮质神经元放电进行了研究。任务包括一个预演“提示周期”，在此期间，目标出现在工作空间的外围，并以四个恒定速度之一沿八个方向之一移动到工作空间的中心。 “跟踪期”包括视觉引导，错误约束的手臂运动，在此过程中，动物从中央起始框沿一条线移动到工作空间的相对外围时跟踪了目标。从行为上讲，动物以高度受限的轨迹跟踪所需的方向和速度。在提示阶段开始时，眼球运动包括扫视到目标，随后在整个提示和跟踪期间，平滑的追踪与扫视混杂在一起。最初，使用方差分析（ANOVA）来测试射击中方向和周期的影响。随后，使用线性回归分析来拟合从提示和跟踪周期到余弦模型的平均发射。通过显着拟合余弦模型确定的方向调整是在提示和跟踪期间放电的一个突出特征。但是，单个提示音的定向调整在提示和跟踪期间并不总是恒定的。在提示和跟踪时间段之间，大约一半的神经元的首选方向（PDs）差异> 45度。提示或跟踪时段中的PD不取决于目标速度。基于在20毫秒仓中的首选方向的计算（即PD轨迹）进行的第二次线性回归分析用于在更精细的时间尺度上检查方向性变化的时间演变。提示周期中的PD轨迹不是笔直的，而是在工作空间中旋转以与跟踪周期PD对齐。顺时针和逆时针旋转都发生。在大部分跟踪期间，PD的轨迹相对笔直。 PD轨迹在提示周期中向轨迹周期的首选方向的旋转和最终收敛可能反映了视觉信息到运动命令的转换。在提示期间广泛分布的PD轨迹将允许在较宽的空间孔径上检测目标。在提示音轨过渡处发生的PD轨迹的会聚可以充当“未移动”信号，该信号并未由范式明确提供。此外，PD轨迹的旋转和收敛可以为非标准映射提供一种机制。标准映射是指感觉运动转换，其中刺激是触及的对象。非标准映射是将任意刺激映射为任意运动。 PD的移动可以允许将来自任何方向的相关视觉信息转换为适当的运动方向，从而为非标准刺激响应映射提供了神经基础。

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