Role of oscillatory dynamics in prefrontal control of cortical excitability durin

描述（由申请人提供）：有选择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。先前的研究已经确定前额皮质（PFC）是调节这一过程的区域。我们认为，在认知过程中，PFC利用振荡机制与低阶皮层区域的网络活动进行沟通和控制。提出的工作旨在研究振荡相互作用，使PFC在工作记忆期间调节皮层兴奋性的感觉区域。了解PFC参与这一过程的神经机制具有理论和转化意义，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康复进展。这项工作将有两个具体目标。在目的1中，我们将利用皮质电图（ECoG）来研究振荡耦合在前额叶控制感觉皮层兴奋性中的作用。ECoG信号是直接从接受治疗的难治性癫痫患者的大脑皮层获得的

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.