Project 3: Neural Mechanisms for Executive Control of Recall

在之前的资助期间，我们的实验室在识别和表征存储记忆回忆的神经相关方面取得了很大进展。但记忆的一个重要方面仍然几乎完全未知：对记忆回忆的“执行控制”。确定了候选的神经结构和机制后，我们现在准备解决这个问题。在我们提出的项目中，我们的目标是解决关于召回执行控制的最基本问题，它的功能组织。为了做到这一点，我们将比较和对比任务要求回忆的神经相关的时间过程与回忆的行为测量：转换成本。当受试者必须灵活地在两者之间交替时，就会出现转换成本

During the previous funding period, our laboratory has made great progress identifying and characterizing neural correlates of the recall of stored memories. But an important facet of memory remains almost wholly unknown: the "executive control" over memory recall. Having identified candidate neural structures and mechanisms, we are now ready to address this issue. In our proposed project, we aim to address the most fundamental question about executive control of recall, its functional organization. To do so, we will compare and contrast the time-course of neural correlates of the recall of task demands with a behavioral measure of recall: switch costs. Switch costs are seen when subjects must flexibly alternate between performing different, often incompatible, judgments and thus must repeatedly recall and update their internal representations of task demands. Switch costs are increases in reaction time (RT) and errors whose magnitude depends on the time between a cue to switch tasks and task initiation. Thus, switch costs reflect the time needed for a set of rules to be recalled from memory and supplant a set of rules already held "on-line". By comparing neural dynamics of recall with switch costs, we can determine the relationship between this activity and its impact on behavior. We will examine neural activity in brain areas where we have previously identified neural correlates for the recall of task demands: the prefrontal cortex, premotor cortex, and basal ganglia. We found differences in latencies and other neural properties between these areas that suggest different roles in recall. Comparing these properties to a behavioral measure of recall will allow us to tease apart their respective contributions. Monkeys will switch between discriminating the color and orientation; we have already found switch costs in monkeys trained under a similar paradigm. Because executive control over recall and other brain processes is central to intelligent behavior, data from this project has the potential to impact on a wide range of behaviors and human disorders. Executive control is disrupted in a variety of neuropsychiatric disorders such as autism and schizophrenia. By identifying brain structures important for these abilities, discerning their relative roles, and uncovering their neural mechanisms, we can open a path to drug and behavioral therapies designed to alleviate dysfunctions of executive control.