CO-OCCURRING PLASTICITY IN DISTRIBUTED NEURAL NETWORKS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 简介： 重复概念处理的刺激结果在行为易化（启动）和功能激活减少左腹外侧前额叶皮层（VLPFC）和后部新皮层区域。虽然最初假设，以反映新皮层调谐，重复诱导的激活减少最近已与刺激反应学习。 具体目标： 为了研究皮层调谐和反应学习是否共同发生，并确定反应学习影响皮层激活的表征水平，使用事件相关fMRI检查三个水平的重复效应：（a）概念重复，（B）刺激-决策重复，和（c）刺激-反应重复。 方法和材料： 事件相关功能磁共振成像测量BOLD活动在研究和测试块的实验。在研究过程中，参与者对单词进行两个语义分类任务之一。随后，所研究的单词被表示（概念重复）沿着与一组新的单词（无重复）。一半的旧单词被归类在相同的决定，在研究（任务内重复），一半被归类根据其他决定（跨任务重复）。在跨任务试验中，一半要求与研究时相同的反应（反应重复），另一半要求不同的反应（反应转换）。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: Repeated conceptual processing of a stimulus results in behavioral facilitation (priming) and functional activation reductions in left ventrolateral prefrontal cortex (VLPFC) and posterior neocortical regions. While initially posited to reflect neocortical tuning, repetition-induced activation reductions have been recently associated with stimulus-response learning. Specific Aims: To investigate whether cortical tuning and response learning co-occur and to determine the representational level at which response learning impacts cortical activation, event-related fMRI was used to examine repetition effects at three levels: (a) conceptual repetition, (b) stimulus-decision repetition, and (c) stimulus-response repetition. Methods & Materials: Event-related fMRI measured BOLD activity during both study and test blocks of the experiment. During study, participants performed one of two semantic classification tasks on words. Subsequently, studied words were represented (conceptual repetition) along with a set of novel words (no repetition). Half of the old words were classified under the same decision as at study (within-task repetition), and half were classified according to the other decision (across-task repetition). Of the across-task trials, half required the same response as at study (response repetition) and half a different response (response switch).