Narayanan Nandakumar S, Laubach Mark
The John B. Pierce Laboratory, Yale University School of Medicine, New Haven, Connecticut 06519, USA.
J Neurophysiol. 2009 Jun;101(6):2859-71. doi: 10.1152/jn.90615.2008. Epub 2009 Apr 1.
To understand how different parts of the frontal cortex control the timing of action, we characterized the firing patterns of single neurons in two areas of rodent frontal cortex-dorsomedial prefrontal cortex (dmPFC) and motor cortex-during a simple reaction time task. Principal component analysis was used to identify major patterns of delay-related activity in frontal cortex: ramping activity and sustained delay activity. These patterns were similar in dmPFC and motor cortex and did not change as animals learned to respond at novel delays. Many neurons in both areas were modulated early in the delay period. Other neurons were modulated in a persistent manner over the duration of the delay period. Delay-related modulations started earlier in motor cortex than in dmPFC and terminated around different task events (at the time of release in dmPFC, just before release of the lever in motor cortex). A subpopulation of neurons was found in dmPFC, but not motor cortex, that fired in response to the trigger stimulus. These results suggest that populations of neurons in rodent frontal cortex are coordinated during delay periods to enable proactive inhibitory control of action.
为了解额叶皮质的不同部分如何控制动作时机，我们在一项简单反应时任务中，对啮齿动物额叶皮质的两个区域——背内侧前额叶皮质（dmPFC）和运动皮质——中单个神经元的放电模式进行了特征描述。主成分分析用于识别额叶皮质中与延迟相关活动的主要模式：斜坡活动和持续延迟活动。这些模式在dmPFC和运动皮质中相似，并且在动物学会在新的延迟时间做出反应时没有改变。两个区域中的许多神经元在延迟期早期受到调制。其他神经元在延迟期持续时间内以持续的方式受到调制。与延迟相关的调制在运动皮质中比在dmPFC中开始得更早，并在不同的任务事件时终止（在dmPFC中是在释放时，在运动皮质中是在杠杆释放前）。在dmPFC中发现了一个神经元亚群，但在运动皮质中没有，它们对触发刺激做出反应。这些结果表明，啮齿动物额叶皮质中的神经元群体在延迟期是协调的，以实现对动作的主动抑制控制。
