Grent-'t-Jong Tineke, Oostenveld Robert, Jensen Ole, Medendorp W Pieter, Praamstra Peter
Radboud University Nijmegen Medical Centre, Dept. of Neurology, PO Box 9101, 6500 HB Nijmegen, The Netherlands; Radboud University Nijmegen, Donders Institute for Brain, Cognition, and Behaviour, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
Neuroimage. 2013 Dec;83:27-34. doi: 10.1016/j.neuroimage.2013.06.051. Epub 2013 Jun 21.
Neurophysiological studies in non-human primates have provided evidence for simultaneous activation of competing responses in the (pre)motor cortex. Human evidence, however, is limited, partly because experimental approaches have often mapped competing responses to paired effectors represented in opposite hemispheres, which restricts the analysis to between-hemisphere comparisons and allows simultaneous execution. A demonstration of competition between different movement plans in the motor cortex is more compelling when simultaneous execution of the alternative responses is ruled out and they are represented in one motor cortex. Therefore, in the current MEG study we have used a unimanual Eriksen flanker paradigm with alternative responses assigned to flexion and extension of the right index finger, activating different direction-sensitive neurons within the finger representation area of the same motor cortex. Results showed that for stimuli eliciting response competition the pre-response motor cortex beta-band (17-29 Hz) power decreased stronger than for stimuli that did not induce response competition. Furthermore, response competition elicited an additional pre-response mid-frontal high-gamma band (60-90 Hz) power increase. Finally, larger gamma-band effect sizes correlated with greater behavioral response delay induced by response competition. Taken together, our results provide evidence for co-activation of competing responses in the human brain, consistent with evidence from non-human primates.
对非人类灵长类动物的神经生理学研究为（前）运动皮层中竞争性反应的同时激活提供了证据。然而，人类方面的证据有限，部分原因在于实验方法通常将竞争性反应映射到相对半球中所代表的成对效应器上，这将分析限制在半球间比较，并且允许同时执行。当排除替代反应的同时执行且它们在一个运动皮层中得到表征时，运动皮层中不同运动计划之间竞争的证明更具说服力。因此，在当前的脑磁图（MEG）研究中，我们使用了一种单手的埃里克森侧翼范式，将替代反应分配给右手食指的屈伸，从而激活同一运动皮层手指表征区域内不同的方向敏感神经元。结果表明，对于引发反应竞争的刺激，反应前运动皮层的β波段（17 - 29赫兹）功率下降幅度比未引发反应竞争的刺激更大。此外，反应竞争引发了反应前额中高γ波段（60 - 90赫兹）功率的额外增加。最后，更大的γ波段效应大小与反应竞争引起的更大行为反应延迟相关。综上所述，我们的结果为人类大脑中竞争性反应的共同激活提供了证据，这与非人类灵长类动物的证据一致。
