Tzagarakis Charidimos, West Sarah, Pellizzer Giuseppe
Brain Sciences Center, Veterans Affairs Health Care Service Minneapolis, MN, USA ; Department of Neuroscience, University of Minnesota Minneapolis, MN, USA.
Brain Sciences Center, Veterans Affairs Health Care Service Minneapolis, MN, USA ; College of Biological Sciences, University of Minnesota Minneapolis, MN, USA.
Front Neurosci. 2015 Jul 21;9:246. doi: 10.3389/fnins.2015.00246. eCollection 2015.
In time-constraint activities, such as sports, it is advantageous to be prepared to act even before knowing precisely what action will be needed. Here, we studied the relation between neural oscillations during motor preparation and amount of uncertainty about the direction of the upcoming target. Ten right-handed volunteers participated in a cued center-out task. A brief visual cue identified the region of space in which the target would appear. Three cue sizes were used to vary the amount of information about the direction of the upcoming target. The target appeared at a random location within the region indicated by the cue, and the participants moved a joystick-controlled cursor toward it. Time-frequency analyses showed phasic increases of power in low (delta/theta: <7 Hz) and high (gamma: >30 Hz) frequency-bands in relation to the onset of visual stimuli and of the motor response. More importantly in regard to motor preparation, there was a tonic reduction of power in the alpha (8-12 Hz) and beta (14-30 Hz) bands during the period between cue presentation and target onset. During motor preparation, the main source of change of power of the alpha band was localized over the contralateral sensorimotor region and both parietal cortices, whereas for the beta-band the main source was the contralateral sensorimotor region. During cue presentation, the reduction of power of the alpha-band in the occipital lobe showed a brief differentiation of condition: the wider the visual cue, the more the power of the alpha-band decreased. However, during motor preparation, only the power of the beta-band was dependent on directional uncertainty: the less the directional uncertainty, the more the power of the beta-band decreased. In conclusion, the results indicate that the power in the alpha-band is associated briefly with cue size, but is otherwise an undifferentiated indication of neural activation, whereas the power of the beta-band reflects the level of motor preparation.
在诸如体育等有时间限制的活动中，甚至在确切知道需要采取何种行动之前就做好行动准备是很有利的。在此，我们研究了运动准备期间的神经振荡与即将出现的目标方向的不确定性程度之间的关系。十名右利手志愿者参与了一个提示性的中心向外任务。一个简短的视觉提示确定了目标将出现的空间区域。使用三种提示大小来改变关于即将出现的目标方向的信息量。目标出现在提示所指示区域内的随机位置，参与者将操纵杆控制的光标移向目标。时频分析显示，与视觉刺激和运动反应的开始相关，低频（δ/θ：<7Hz）和高频（γ：>30Hz）频段的功率有阶段性增加。更重要的是关于运动准备，在提示呈现和目标出现之间的时间段内，α（8 - 12Hz）和β（14 - 30Hz）频段的功率有持续性降低。在运动准备期间，α频段功率变化的主要来源位于对侧感觉运动区和双侧顶叶皮层，而对于β频段，主要来源是对侧感觉运动区。在提示呈现期间，枕叶α频段功率的降低显示出条件的短暂差异：视觉提示越宽，α频段的功率下降越多。然而，在运动准备期间，只有β频段的功率取决于方向不确定性：方向不确定性越小，β频段的功率下降越多。总之，结果表明α频段的功率与提示大小有短暂关联，但在其他方面是神经激活的无差异指示，而β频段的功率反映了运动准备的水平。
