Cortical-cortical interactions in executive control

人们普遍认为，人类认知是由参与任务的分布式神经网络支持的 依赖的方式。前额叶皮层（PFC）是至关重要的自上而下的控制这样的网络在多个 认知领域包括注意力、语言和记忆。尽管“自上而下”一词被广泛使用， 令人惊讶的是，很少有神经认知研究来研究如何或在何处将其实例化。 神经层面例如，在认知任务中，不知道活动的兴奋与抑制 表示单一的增益控制机制，使得活动沿着一个方向被向上或向下调节。 由一个控制机制或自上而下的控制是否反映了多个和 不同的RFC依赖性兴奋和抑制机制。我们建议PFC独立行使 兴奋和抑制控制，以支持目标导向的行为。为了解决这个假设，我们将执行 一系列的实验，检查是否由不同的兴奋性和抑制性支持自上而下， 具有独立时间进程的机制。我们将进一步评估是否支持自顶向下控制 通过基于预设指令（任务集自上而下）的某类刺激的兴奋或抑制 PFC自上而下的控制是否也能在早期知觉中迅速发挥兴奋和抑制作用？ 在试验的基础上进行试验（自上而下的控制）。为了解决这些问题，我们将执行 正常对照组的fMRI研究，植入硬膜下的患者的皮质电图研究（ECoG）， 在以中外侧PFC为中心的局灶性PFC损伤患者中进行的电极和病变研究（BA 44/9/46）。 ECoG研究将重点关注我们已经显示的新描述的高伽马响应（70-250 Hz） 是大脑皮层激活的有力神经标记患者病变研究将与平行 正常人中外侧PFC的TMS失活研究。病变和TMS研究将评估 在ECoG和TMS研究中观察到的提议的横向PFC激活对任务表现至关重要。如果 该项目的成果将使用聚合方法提供关于全氟化学品在以下方面作用的关键数据： 自上而下的控制这项工作具有广泛的理论意义，也将为翻译提供参考。 对PFC损伤的神经和神经外科患者进行基于生理的干预。

It is widely accepted that human cognition is supported by distributed neural networks engaged in a task dependent manner. Prefrontal cortex (PFC) is crucial to top-down control of such networks across multiple cognitive domains including attention, language and memory. Despite the widespread use of the term "topdown" control there is surprisingly little neurocognitive research on how or where this might be instantiated at a neural level. For instance, it is unknown whether excitation vs inhibition of activity in cognitive tasks represents a unitary gain control mechanism, such that activity is either up or down regulated along one continuum by one control mechanism or whether top-down control reflects the net activity of multiple and distinct RFC-dependent excitatory and inhibitory mechanisms. We propose that PFC exerts independent excitatory and inhibitory control to support goal-directed behavior. To address this hypothesis we will perform a series of experiments examining whether top-down is supported by distinct excitatory and inhibitory mechanisms with independent time courses. We will further assess whether top-down control is supported by excitement or inhibition of all of a certain class of stimuli based on pre-set instructions (Task Set top-down control) or whether PFC top-down control can also rapidly exert excitation and inhibition in early perceptual regions on a trial by trial basis (Trial-by-Trial top-down control). To address these questions we will perform fMRI studies in normal controls, electrocorticography studies (ECoG) in patients with implanted subdural electrodes and lesion studies in patients with focal PFC damage centered in mid-lateral PFC (BA 44/9/46). The ECoG studies will focus on the newly described high gamma response (70-250 Hz) that we have shown to be a robust neural marker of cortical activation. The patient lesion studies will be coupled with parallel TMS inactivation studies of mid-lateral PFC in normals. The lesion and TMS studies will assess whether the proposed lateral PFC activations observed in the ECoG and TMS studies are critical to task performance. If successful the results of this project will provide crucial data using converging methods on the role of PFC in top-down control. The proposed work has broad theoretical implications and will also inform translational physiologically based interventions for neurological and neurosurgical patients with PFC damage.