Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands.
J Neurophysiol. 2021 Dec 1;126(6):1891-1902. doi: 10.1152/jn.00198.2021. Epub 2021 Nov 3.
Although beta-band activity during motor planning is known to be modulated by uncertainty about where to act, less is known about its modulations to uncertainty about how to act. To investigate this issue, we recorded oscillatory brain activity with EEG while human participants ( = 17) performed a hand choice reaching task. The reaching hand was either predetermined or of participants' choice, and the target was close to one of the two hands or at about equal distance from both. To measure neural activity in a motion artifact-free time window, the location of the upcoming target was cued 1,000-1,500 ms before the presentation of the target, whereby the cue was valid in 50% of trials. As evidence for motor planning during the cuing phase, behavioral observations showed that the cue affected later hand choice. Furthermore, reaction times were longer in the choice trials than in the predetermined trials, supporting the notion of a competitive process for hand selection. Modulations of beta-band power over central cortical regions, but not alpha-band or theta-band power, were in line with these observations. During the cuing period, reaches in predetermined trials were preceded by larger decreases in beta-band power than reaches in choice trials. Cue direction did not affect reaction times or beta-band power, which may be due to the cue being invalid in 50% of trials, retaining effector uncertainty during motor planning. Our findings suggest that effector uncertainty modulates beta-band power during motor planning. Although reach-related beta-band power in central cortical areas is known to modulate with the number of potential targets, here we show, using a cuing paradigm, that the power in this frequency band, but not in the alpha or theta band, is also modulated by the uncertainty of which hand to use. This finding supports the notion that multiple possible effector-specific actions can be specified in parallel up to the level of motor preparation.
尽管已知运动规划期间的β波段活动会受到行动地点不确定性的调节，但对于其对行动方式不确定性的调节知之甚少。为了研究这个问题，我们在人类参与者（n=17）进行手部选择伸手任务时，使用 EEG 记录了振荡脑活动。伸手的手是预先确定的还是参与者的选择，目标靠近双手之一或大约与双手等距离。为了在运动伪影-free 的时间窗口中测量神经活动，即将到来的目标的位置在目标呈现前 1000-1500 毫秒被提示，其中提示在 50%的试验中有效。作为在提示阶段进行运动规划的证据，行为观察表明提示会影响后来的手选择。此外，在选择试验中反应时间比在预定试验中长，这支持了手选择的竞争过程的概念。β波段功率的调制在中央皮质区域，而不是α波段或θ波段功率，与这些观察结果一致。在提示期间，与选择试验相比，预定试验中的伸手动作之前β波段功率的下降幅度更大。提示方向不影响反应时间或β波段功率，这可能是由于提示在 50%的试验中无效，在运动规划期间保持了效应器的不确定性。我们的发现表明，效应器的不确定性会调节运动规划期间的β波段功率。尽管与伸手相关的中央皮质区域的β波段功率已知会随着潜在目标数量的变化而变化，但在这里我们使用提示范式表明，该频率带中的功率（而不是α或θ带中的功率）也会受到使用哪只手的不确定性的调节。这一发现支持了这样一种观点，即多个可能的特定于效应器的动作可以在运动准备的水平上并行指定。
