Endogenous neural activity: neurophysiology, optical imaging, fMRI, and behavior.

 描述(由申请人提供)：我们最近确定了一种反映受试者在任务中投入程度的神经活动类型。我们使用固有信号光学成像和功能磁共振成像测量了这种与任务相关的活动，它独立于外部视觉刺激，而与大脑内部状态(如唤醒和内源性注意)有关。在这里，我们提出了一系列实验，使用广泛的神经生理学方法来测试与任务相关的大脑活动的几个假说。目标1将测试血流动力学活动(通过光学成像或功能磁共振成像测量)是否可以分离为神经上不同的刺激诱发成分和任务相关成分的线性总和。目标2将测试任务相关成分是否广泛存在，但可能是任务通道(例如，视觉与听觉)的函数，而不是空间上的全局。目标3将测试与任务相关的部分是否反映了投入程度(唤醒或注意力的一种形式)，从而是奖励、难度和时机的函数。我们建议研究的内源性过程牵涉到各种神经和精神障碍。例如，ADHD患者表现出各种各样的注意力缺陷，但他们最明显的缺陷与“持续注意力”有关，即在很长一段时间内保持对一项不常见任务的稳定表现。我们建议研究的任务相关成分很可能与持续注意力有关，而从拟议的实验中获得的知识可能会为ADHD和相关障碍提供见解。

 DESCRIPTION (provided by applicant): We have recently identified a type of neural activity that reflects the subject's engagement in a task. This task- related activity, which we have measured using both intrinsic-signal optical imaging and functional magnetic resonance imaging, is independent of external visual stimuli and is, instead, linked to internal brain states such as arousal and endogenous attention. Here, we propose a series of experiments that test several hypotheses about task-related brain activity, using a wide range of neurophysiological methods. Aim 1 will test whether hemodynamic activity (measured with optical imaging or with fMRI) can be separated into a linear sum of neurally distinct stimulus-evoked and task-related components. Aim 2 will test whether the task-related component is widespread but possibly a function of task modality (e.g. visual vs. auditory) and not spatially global. Aim 3 will test whether the task-related component reflects the degree of engagement (a form of arousal or attention) and is thus a function of reward, difficulty and timing. The endogenous processes that we propose to investigate are implicated a variety of neurological and psychiatric disorders. For example, individuals with ADHD demonstrate a wide variety of attentional deficits, but their most pronounced deficits are related to "sustained attention", i.e., maintaining a steady level of performance on an infrequent task over a prolonged period of time. It is likely that the task-related component that we are proposing to study is related to sustained attention, and knowledge gained from the proposed experiments may provide insights into ADHD and related disorders.