Abstract：
Precision reaching often requires corrective submovements to obtain the desired goal. Most studies of reaching have focused on single initial movements, and implied the cortical encoding model was the same for all submovements. However, corrective submovements may show different encoding patterns from the initial submovement with distinct patterns of activation across the population. Two rhesus macaques performed a precision center-out-task with small targets. Neural activity from single units in the primary motor cortex and associated behavioral data were recorded to evaluate movement characteristics. Neural population data and individual neuronal firing rates identified with a peak finding algorithm to identify peaks in hand speed were examined for encoding differences between initial and corrective submovements. Individual neurons were fitted with a regression model that included the reach vector, position, and speed to predict firing rate. For both initial and corrective submovements, the largest effect remained movement direction. We observed a large subset changed their preferred direction greater than 45° between initial and corrective submovements. Neuronal depth of modulation also showed considerable variation when adjusted for movement speed. By using principal component analysis, neural trajectories of initial and corrective submovements progressed through different neural subspaces. These findings all suggest that different neural encoding patterns exist for initial and corrective submovements within the cortex. We hypothesize that this variation in how neurons change to encode small, corrective submovements might allow for a larger portion of the neural space being used to encode a greater range of movements with varying amplitudes and levels of precision.NEW & NOTEWORTHY Neuronal recordings matched with kinematic behavior were collected in a precision center-out task that often required corrective movements. We reveal large differences in preferred direction and depth of modulation between initial and corrective submovements across the neural population. We then present a model of the neural population describing how these shifts in tuning create different subspaces for signaling initial and corrective movements likely to improve motor precision.
摘要：
精确到达通常需要校正子移动以获得期望的目标。大多数关于到达的研究都集中在单个初始运动上，并暗示皮层编码模型对于所有子运动都是相同的。然而,校正子移动可以显示与初始子移动不同的编码模式,具有跨群体的不同激活模式。两只恒河猴以小目标执行了精确的中心任务。记录来自初级运动皮层中单个单元的神经活动和相关行为数据以评估运动特征。检查了通过寻峰算法识别手速峰值的神经群体数据和单个神经元放电率，以编码初始和校正子运动之间的差异。对单个神经元进行回归模型拟合，其中包括到达向量，position,和速度来预测射击率。对于初始和校正子运动，最大的影响仍然是运动方向。我们观察到，在初始和校正子运动之间，一个很大的子集改变了他们的首选方向超过45度。当调整运动速度时，神经元调制深度也显示出相当大的变化。通过利用主成分分析，初始和校正子运动的神经轨迹通过不同的神经子空间进行。这些发现都表明，皮层内的初始和校正子运动存在不同的神经编码模式。我们假设神经元如何改变编码的这种变化很小，校正子运动可能允许神经空间的较大部分用于编码具有变化幅度和精度水平的更大范围的运动。
