Role of oscillatory dynamics in prefrontal control of cortical excitability durin

描述（由申请人提供）：选择性地促进或抑制信息处理的能力对于高阶认知任务（如工作记忆）至关重要。以前的工作已经确定了前额叶皮层（PFC）作为区域调制这个过程。我们认为，PFC利用振荡机制沟通和控制网络活动在较低级别的皮层区域在认知过程中。本研究旨在探讨在工作记忆过程中，前额叶皮层对感觉区皮层兴奋性的调节机制。PFC参与这一过程的神经机制的知识具有理论和翻译意义，并可能导致有针对性的康复方法的发展，以治疗和监测脑损伤患者的恢复进展。这项工作将有两个具体目标。目的1：利用皮层电图（ECoG）研究振荡耦合在感觉皮层兴奋性的前额叶控制中的作用。ECoG信号直接从接受难治性癫痫治疗的患者的皮层获得， 当受试者执行多模态工作记忆任务时记录，该任务需要选择性地注意不同感觉模态中的刺激。与非侵入性记录方法相比，ECoG方法具有许多优点，包括非常高的空间和时间分辨率以及增强的信噪比。我们假设，PFC使用振荡机制来控制和增强PFC和低阶皮层区域之间的网络活动，以促进相关信息的处理，这一假设将通过计算连接措施，如相位相干性，频谱格兰杰因果关系，并在不同的任务期间电极之间的交叉频率耦合进行测试。此外，我们预测，PFC和感觉区之间的连接水平越高，任务表现越好，α（~ 10 Hz）振荡的调制也越大，这是一个公认的皮质兴奋性指数，超过了感觉区。在目标2中，我们将建立在我们的研究结果，从以前的目标和评估的因果关系和重组的前额叶皮层在调制感觉处理利用脑电图（EEG）记录与局灶性额叶损伤的患者，由于中风以及年龄匹配的控制。当受试者执行与目标1中所用任务相似的任务时，将记录EEG。我们假设，与任务表现下降时，参加对侧的刺激受损PFC，我们进一步预测，完整的额叶皮层将补偿受损的皮层，这种补偿将通过患者完整的额叶半球和后部感觉区之间更高水平的连接来表现与年龄匹配的对照组相比。

DESCRIPTION (provided by applicant): The ability to selectively facilitate or suppress the processing of information is essential for higher-order cognitive tasks such as working memory. Previous work has identified the prefrontal cortex (PFC) as the region modulating this processing. We propose that the PFC utilizes oscillatory mechanisms to communicate with and control network activity in lower-order cortical areas during cognition. The proposed work seeks to investigate the oscillatory interactions which allow the PFC to modulate cortical excitability i sensory areas during working memory. Knowledge of the neural mechanisms of PFC engagement in this process has both theoretical as well as translational implications and may lead to development of targeted rehabilitation methods to treat and monitor the progress of recovery for patients suffering from brain injury. This work will be carried out with two specific aims. In Aim 1, we will utilize electrocorticography (ECoG) to investigate the role of oscillatory coupling in the prefrontal control of sensory cortex excitability. ECoG signals, which are obtained directly from the cortex of patients undergoing treatment for refractory epilepsy, will be recorded while subjects perform a multimodal working memory task requiring selective attention to stimuli in different sensory modalities. The ECoG method has many benefits compared with noninvasive recording methods including exceptionally high spatial and temporal resolutions as well as an enhanced signal to noise ratio. We hypothesize that the PFC uses oscillatory mechanisms to control and enhance network activity between PFC and lower-order cortical areas in order to facilitate the processing of relevant information, and this hypothesis will be tested by computing connectivity measures such as phase coherence, spectral Granger causality, and cross frequency coupling between electrodes during different task periods. Furthermore, we predict that greater levels of connectivity between PFC and sensory areas will be associated with better task performance, as well as with an increased modulation of alpha (~10Hz) oscillations, a putative index of cortical excitability, over sensory areas. In Aim 2, we wll build on our findings from the previous aim and assess the causal role and reorganization of prefrontal cortex in modulating sensory processing utilizing electroencephalographic (EEG) recordings from patients with focal frontal lobe damage due to stroke as well as age-matched controls. EEG will be recorded while subjects perform a task similar to that used in Aim 1. We hypothesize that, concurrent with decreased task performance when attending to stimuli contralateral to damaged PFC, patients will show a decreased amount of alpha modulation over sensory areas ipsilateral to damaged PFC. We further predict that intact frontal cortex will compensate for lesioned cortex and that this compensation will be manifested through a greater level of connectivity between the intact frontal hemisphere and posterior sensory areas in patients compared with age-matched controls.