Deutsches Primatenzentrum GmbH, Kellnerweg 4, 37077 Göttingen, Germany.
Electrical Engineering Department.
J Neurosci. 2018 Jun 20;38(25):5759-5773. doi: 10.1523/JNEUROSCI.2557-17.2018. Epub 2018 May 24.
Our voluntary grasping actions lie on a continuum between immediate action and waiting for the right moment, depending on the context. Therefore, studying grasping requires an investigation into how preparation time affects this process. Two macaque monkeys (; one male, one female) performed a grasping task with a short instruction followed by an immediate or delayed go cue (0-1300 ms) while we recorded in parallel from neurons in the grasp preparation relevant area F5 that is part of the ventral premotor cortex, and the anterior intraparietal area (AIP). Initial population dynamics followed a fixed trajectory in the neural state space unique to each grip type, reflecting unavoidable movement selection, then diverged depending on the delay, reaching unique states not achieved for immediately cued movements. Population activity in the AIP was less dynamic, whereas F5 activity continued to evolve throughout the delay. Interestingly, neuronal populations from both areas allowed for a readout tracking subjective anticipation of the go cue that predicted single-trial reaction time. However, the prediction of reaction time was better from F5 activity. Intriguingly, activity during movement initiation clustered into two trajectory groups, corresponding to movements that were either "as fast as possible" or withheld movements, demonstrating a widespread state shift in the frontoparietal grasping network when movements must be withheld. Our results reveal how dissociation between immediate and delay-specific preparatory activity, as well as differentiation between cortical areas, is possible through population-level analysis. Sometimes when we move, we consciously plan our movements. At other times, we move instantly, seemingly with no planning at all. Yet, it's unclear how preparation for movements along this spectrum of planned and seemingly unplanned movement differs in the brain. Two macaque monkeys made reach-to-grasp movements after varying amounts of preparation time while we recorded from the premotor and parietal cortex. We found that the initial response to a grasp instruction was specific to the required movement, but not to the preparation time, reflecting required movement selection. However, when more preparation time was given, neural activity achieved unique states that likely related to withholding movements and anticipation of movement, shedding light on the roles of the premotor and parietal cortex in grasp planning.
我们的自愿抓握动作位于即时动作和等待合适时机之间的连续体上,具体取决于上下文。因此,研究抓握需要调查准备时间如何影响这个过程。两只猕猴(一雄一雌)在短指令后进行抓握任务,然后立即或延迟发出 Go 信号(0-1300ms),同时我们从位于抓握准备相关区域 F5 的神经元和前内顶叶区域 (AIP) 进行平行记录。初始群体动态遵循每个抓握类型特有的神经状态空间中的固定轨迹,反映出不可避免的运动选择,然后根据延迟发散,达到即时 cue 运动无法达到的独特状态。AIP 中的群体活动不那么动态,而 F5 活动在整个延迟过程中继续演变。有趣的是,来自两个区域的神经元群体允许读取跟踪对 Go 信号的主观预期,该预期可以预测单次试验反应时间。然而,F5 活动的反应时间预测更好。有趣的是,运动启动期间的活动聚类为两个轨迹组,对应于尽可能快地运动或抑制运动,表明在必须抑制运动时,额顶抓握网络中的状态广泛转移。我们的研究结果揭示了通过群体水平分析如何实现即时和延迟特定准备活动之间的分离,以及皮质区域之间的分化。有时当我们移动时,我们会有意识地计划我们的动作。在其他时候,我们会立即移动,似乎没有任何计划。然而,目前尚不清楚在大脑中,沿着计划和看似无计划运动的这个谱准备运动有何不同。两只猕猴在不同的准备时间后进行伸手抓握动作,而我们则从前运动和顶叶皮层进行记录。我们发现,对抓握指令的初始反应特定于所需的运动,但与准备时间无关,反映了所需的运动选择。然而,当给予更多的准备时间时,神经活动达到了可能与抑制运动和运动预期相关的独特状态,揭示了前运动和顶叶皮层在抓握计划中的作用。