Abstract

Accumulating evidence supports the view that the medial part of the posterior parietal cortex (mPPC) is involved in the planning of reaching, but while plenty of studies investigated reaching performed toward different directions, only a few studied different depths. Here, we investigated the causal role of mPPC (putatively, human area V6A–hV6A) in encoding depth and direction of reaching. Specifically, we applied single-pulse transcranial magnetic stimulation (TMS) over the left hV6A at different time points while 15 participants were planning immediate, visually guided reaching by using different eye-hand configurations. We found that TMS delivered over hV6A 200 ms after the Go signal affected the encoding of the depth of reaching by decreasing the accuracy of movements toward targets located farther with respect to the gazed position, but only when they were also far from the body. The effectiveness of both retinotopic (farther with respect to the gaze) and spatial position (far from the body) is in agreement with the presence in the monkey V6A of neurons employing either retinotopic, spatial, or mixed reference frames during reach plan. This work provides the first causal evidence of the critical role of hV6A in the planning of visually guided reaching movements in depth.

中文翻译：

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人体内侧后顶叶皮层的经颅磁刺激在达到计划期间破坏深度编码

摘要

越来越多的证据支持后顶叶皮层 (mPPC) 的内侧部分参与到达计划的观点，但是虽然大量研究调查了向不同方向进行的伸展，但只有少数研究了不同的深度。在这里，我们研究了 mPPC（假定为人类区域 V6A-hV6A）在编码深度和到达方向中的因果作用。具体来说，我们在不同时间点对左侧 hV6A 应用单脉冲经颅磁刺激 (TMS)，同时 15 名参与者计划通过使用不同的眼手配置立即、视觉引导到达。我们发现，在 Go 信号后 200 ms 传递超过 hV6A 的 TMS 通过降低朝向相对于凝视位置更远的目标的运动精度来影响到达深度的编码，但只有当他们也远离尸体时。视网膜（相对于凝视更远）和空间位置（远离身体）的有效性与猴子 V6A 中存在的神经元一致，在到达计划期间使用视网膜、空间或混合参考框架。这项工作提供了 hV6A 在规划视觉引导的深度到达运动中的关键作用的第一个因果证据。