Cortical-cortical interactions in executive control

人们普遍认为，人类的认知是由参与任务的分布式神经网络支持的 依赖的态度。前额叶皮质(PFC)对于自上而下控制这种跨越多个 认知域包括注意力、语言和记忆。尽管“自上而下”一词被广泛使用 控制--令人惊讶的是，很少有关于如何或在哪里实例化它的神经认知研究 一种神经层面。例如，在认知任务中，兴奋性活动与抑制性活动之间的关系尚不清楚 表示一种单一的增益控制机制，这样活动就可以按照一种方式进行上下调节 或者自上而下的控制是否反映了多个和 不同的RFC依赖的兴奋和抑制机制。我们建议PFC发挥独立的作用 兴奋性和抑制性控制，以支持目标导向行为。为了解决这一假设，我们将执行 检验自上而下是否受到明显的兴奋和抑制的支持的一系列实验 具有独立时间进程的机构。我们将进一步评估是否支持自上而下的控制 通过基于预置指令(任务设置自上而下)对所有特定类别的刺激进行兴奋或抑制 控制)，或者PFC自上而下控制是否也能在知觉早期迅速地发挥兴奋和抑制作用 在逐个试行的基础上(逐个试行自上而下的控制)。为了解决这些问题，我们将执行 正常对照组的功能磁共振成像和植入硬膜下的患者的皮层脑电研究 以中外侧为中心的PFC局灶性损害患者的电极和病变研究(BA 44/9/46)。 ECoG研究将重点放在我们已经显示的最新描述的高伽马反应(70-250赫兹)上 成为皮质激活的强有力的神经标志物。患者病变研究将与平行研究相结合 正常人中外侧PFC的TMS失活研究。病变和TMS研究将评估是否 在ECoG和TMS研究中观察到的侧向PFC激活对任务绩效至关重要。如果 该项目的成功结果将提供使用汇聚方法的关键数据，以了解PFC在 自上而下的控制。这项拟议的工作具有广泛的理论意义，也将为翻译 神经科和神经外科PFC受损患者的生理学干预。

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.