Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
Sci Rep. 2019 Jan 30;9(1):936. doi: 10.1038/s41598-018-37302-2.
Several investigations at a single-cell level demonstrated that the medial posterior parietal area V6A is involved in encoding reaching and grasping actions in different visual conditions. Here, we looked for a "low-dimensional" representation of these encoding processes by studying macaque V6A neurons tested in three different tasks with a dimensionality reduction technique, the demixed principal component analysis (dPCA), which is very suitable for neuroprosthetics readout. We compared neural activity in reaching and grasping tasks by highlighting the portions of population variance involved in the encoding of visual information, target position, wrist orientation and grip type. The weight of visual information and task parameters in the encoding process was dependent on the task. We found that the distribution of variance captured by visual information in the three tasks did not differ significantly among the tasks, whereas the variance captured by target position and grip type parameters were significantly higher with respect to that captured by wrist orientation regardless of the number of conditions considered in each task. These results suggest a different use of relevant information according to the type of planned and executed action. This study shows a simplified picture of encoding that describes how V6A processes relevant information for action planning and execution.
几项单细胞水平的研究表明，内侧后顶叶区域 V6A 参与了在不同视觉条件下编码到达和抓取动作。在这里，我们通过使用一种降维技术——混合主成分分析（dPCA），研究了猕猴 V6A 神经元在三个不同任务中的测试结果，寻找这些编码过程的“低维”表示，这种技术非常适合神经假肢的读取。我们通过突出参与视觉信息、目标位置、手腕方向和抓握类型编码的种群方差部分，比较了到达和抓取任务中的神经活动。在编码过程中，视觉信息和任务参数的权重取决于任务。我们发现，在三个任务中，视觉信息捕获的方差分布在任务之间没有显著差异，而目标位置和抓握类型参数捕获的方差明显高于手腕方向捕获的方差，无论在每个任务中考虑了多少条件。这些结果表明，根据计划和执行动作的类型，对相关信息的使用不同。这项研究展示了一种简化的编码图像，描述了 V6A 如何处理与动作规划和执行相关的信息。
