Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen, 6500HB, Nijmegen, The Netherlands.
Proc Natl Acad Sci U S A. 2011 Jun 28;108(26):10708-13. doi: 10.1073/pnas.1107297108. Epub 2011 Jun 13.
The neuronal correlate of perceptual decision making has been extensively studied in the monkey somatosensory system by using a vibrotactile discrimination task, showing that stimulus encoding, retention, and comparison are widely distributed across cortical areas. However, from a network perspective, it is not known what role oscillations play in this task. We recorded local field potentials (LFPs) from diverse cortical areas of the sensorimotor system while one monkey performed the vibrotactile discrimination task. Exclusively during stimulus presentation, a periodic response reflecting the stimulus frequency was observed in the somatosensory regions, suggesting that after initial processing, the frequency content of the stimulus is coded in some other way than entrainment. Interestingly, we found that oscillatory activity in the beta band reflected the dynamics of decision making in the monkey sensorimotor network. During the comparison and decision period, beta activity showed a categorical response that reflected the decision of the monkey and distinguished correct from incorrect responses. Importantly, this differential activity was absent in a control condition that involved the same stimulation and response but no decision making required, suggesting it does not merely reflect the maintenance of a motor plan. We conclude that beta band oscillations reflect the temporal and spatial dynamics of the accumulation and processing of evidence in the sensorimotor network leading to the decision outcome.
感觉运动系统中的神经元决策相关研究在猴子的触觉辨别任务中已经被广泛研究，结果表明刺激的编码、保持和比较广泛分布在皮质区域。然而，从网络的角度来看，还不清楚振荡在这个任务中扮演了什么角色。当一只猴子执行触觉辨别任务时，我们记录了感觉运动系统中不同皮质区域的局部场电位（LFPs）。仅在刺激呈现期间，在感觉区域观察到反映刺激频率的周期性反应，这表明在初始处理后，刺激的频率内容是以某种方式编码的，而不是同步。有趣的是，我们发现β频带中的振荡活动反映了猴子感觉运动网络中决策的动态。在比较和决策期间，β活动表现出一种分类反应，反映了猴子的决策，并将正确和错误的反应区分开来。重要的是，在不涉及决策的控制条件下，这种差异活动不存在，这表明它不仅仅反映了运动计划的维持。我们的结论是，β频带振荡反映了证据在感觉运动网络中积累和处理的时空动态，从而导致决策结果。
