The Study of Task-Level Control Signals Using fMRI

描述（由申请人提供）：认知神经科学的一个主要问题是如何组织特定的神经通路进行任务执行。这个建议的主要假设是，任务水平的控制是实现的，在一定程度上，通过活动持续跨任务试验，并可以使用功能磁共振成像研究。这一假设通过三个具体目标来解决。具体目标1：完善范式设计和分析方法，分离持续和瞬态fMRI信号。主要的假设是，混合块/事件相关的范式可以优化的持续的“控制”信号的准确和灵敏的识别从瞬态的“审判相关”的功能磁共振成像信号。具体目标2：表征在试验中表现出持续活性的不同区域的功能属性。三个一般假设将被测试：1）一些区域将在广泛的任务中表现出持续的活动，暗示它们在一般控制功能中; 2）尽管有这种共性，但对控制的可分离方面的操纵（例如，输入或反应选择）将不同地影响这些区域的特定子集; 3）一些区域将显示与特定任务域相关的持续活动，暗示它们是域特异性控制的来源，或者是控制信号影响正在进行的试验相关处理的位点。具体目标3：使用持续信号的特性来解决记忆提取的特定问题。一些情景提取的研究表明，激活的右额叶区域，并已提出，这种活动可能与“提取模式”。两个相关的假设进行了测试：1）右额叶持续活动将被发现的条件下，要求“重新集体的努力”或“重新集体模式”; 2）右额叶持续活动不会是特定的“回忆”，但也将存在复杂的检索约束时，被放置在“中间水平”之间的回忆和熟悉。作为一个群体，这些研究应该提高我们对大脑中任务控制过程的理解。几种精神和神经疾病（例如，抽动秽语综合征、额叶中风）与控制缺陷有关;对与控制过程相关的神经机制的更深入理解可能允许比目前存在的更具体的诊断、预后或康复方法来解决这些困难。

DESCRIPTION (provided by applicant): A major issue in cognitive neuroscience is how specific neural pathways are organized for task performance. The major hypothesis of this proposal is that task-level control is implemented, in part, by activity sustained across task trials, and can be studied using fMRI. This hypothesis is addressed through 3 Specific Aims. Specific Aim 1: To refine paradigm designs and analysis methods for separating sustained and transient fMRI signals. The main hypothesis is that the mixed block/event related paradigm can be optimized for the accurate and sensitive identification of sustained "control" signals from transient "trial-related" fMRI signals. Specific Aim 2: To characterize the functional attributes of different regions exhibiting sustained activity across trials. Three general hypotheses will be tested: 1) Some regions will exhibit sustained activity across a wide range of tasks, implicating them in general control functions; 2) In spite of this commonality, manipulation of separable aspects of control (e.g., input or response selection) will differentially affect specific subsets of these regions; 3) Some regions will show sustained activity related to specific task domains, implicating them as sources of domain specific control, or as sites at which control signals affect ongoing trial-related processing. Specific Aim 3: To use properties of sustained signals to address issues specific to memory retrieval. Several episodic retrieval studies have shown activation of right frontal regions, and it has been proposed that this activity may be related to "retrieval mode". Two related hypotheses are tested: 1) Right frontal sustained activity will be found across conditions that demand "re-collective effort" or "re-collective mode"; 2) The right frontal sustained activity will not be specific to "recollection", but will also be present when complex retrieval constraints are placed at "intermediate levels" between recollection and familiarity. As a group, these studies should improve our understanding of task control processes in the brain. Several psychiatric and neurological diseases (e.g., Tourette's syndrome, frontal lobe strokes) have been related to deficits of control; a deeper understanding of the neural mechanisms related to control processes may allow more specific diagnostic, prognostic, or rehabilitative approaches to these difficulties than currently exist.