Neural Basis of Endogenous Potentials in Humans

描述(申请人提供)：人类大脑功能可以通过使用脑电(EEG)和脑磁图(MEG)测量活跃神经元产生的微小电流来探测。神经元活动也会导致局部血氧和血流量的变化，这可以用功能磁共振成像(FMRI)来测量。功能磁共振成像提供了认知过程中大脑激活的直接定位，但时间分辨率较低。相反，EEG/MEG提供毫秒级的精确度，但它们在大脑中出现的位置很难确定。这项资助的第一个目标是将fMRI的空间分辨率与EEG/MEG的时间分辨率相结合，以生成大脑激活的时空图。这些地图的准确性将通过直接从大脑内进行的脑电记录来验证(进行这些记录是为了定位耐药癫痫患者的癫痫灶)。这些地图将有助于揭示大脑区域在思考过程中何时何地活跃。拨款的第二个目的是更好地了解这些地图代表的是哪种神经元活动。线性微电极阵列将在相同的受试者和任务中使用，以估计不同皮层的群体突触电流(神经元输入)和神经元放电(输出)。因此，在全脑研究中发现的“激活”将被描述为兴奋与抑制、输入与输出、自上而下与自下而上的交互作用。拟议的研究应该提供关于不同的大脑成像模式如何看待脑功能活动的见解，以及它们如何整合在一起，以便追踪通过思维的人脑的激活通道。这项技术对于定位病理活动也是有用的。此外，所提出的研究可能有助于构建认知的功能神经模型。这样的模型对于了解神经精神障碍中认知是如何被破坏的是必要的。最后，更全面地了解认知潜能的产生，应该会极大地增加它们作为神经或精神疾病患者特定大脑系统功能测试的价值。具体地说，对语言和记忆的研究将为术前无创绘制口才皮质图提供科学基础。

DESCRIPTION (provided by applicant): Human brain function can be probed by measuring the minute currents produced by active neurons using electroencephalography (EEG) and magnetoencephalography (MEG). Neuronal activity also results in localized changes in blood oxygenation and flow, which can be measured using functional magnetic resonance imaging (fMRI). fMRI provides direct localization of brain activation during cognition, but with poor temporal resolution. Conversely, EEG/MEG provides millisecond accuracy, but the location in the brain where they arise is hard to determine. The first aim of this grant is to combine the spatial resolution of fMRI with the temporal resolution of EEG/MEG to produce spatiotemporal maps of brain activation. The accuracy of these maps will be validated using EEG recordings from directly within the brain (conducted in order to localize the seizure focus in patients with pharmaco-resistant epilepsy). These maps will help reveal where and when brain areas are active during thought. The second aim of the grant is to better understand what kind of neuronal activity these maps represent. Linear microelectrode arrays will be used in the same subjects and tasks to estimate population synaptic currents (neuronal inputs) and neuronal firing (outputs) in different cortical layers. The 'activation' found in the whole-brain studies will thus be characterized as excitation vs inhibition, input vs output, and top-down vs bottom-up interactions. The proposed studies should provide insights into how the different brain imaging modalities view functional brain activity, and how they may be integrated in order to trace the passage of activation through the thinking human brain. This technique should also be useful for localizing pathological activity. In addition, the proposed studies may help in the construction of functional neural models for cognition. Such models are necessary to understand how cognition is disrupted in neuropsychiatric disorders. Finally, more complete knowledge regarding the generators of cognitive potentials should greatly increase their value as functional tests for specific brain systems in patients with neurological or psychiatric disease. Specifically, studies on language and memory will provide a scientific basis for the non-invasive mapping of eloquent cortex prior to surgery.