Lin Hai, Li Wei-Ping, Carlson Synnöve
Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
Department of Neurosurgery, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China.
Front Hum Neurosci. 2019 Jan 28;13:2. doi: 10.3389/fnhum.2019.00002. eCollection 2019.
Top-down modulation is engaged during multiple stages of working memory (WM), including expectation, encoding, and maintenance. During WM maintenance period, an "incidental cue" can bring one of the two items into a privileged state and make the privileged item be recalled with higher precision, despite being irrelevant to which one to be probed as the target. With regard to the different representational states of WM, it's unclear whether there is top-down modulation on earth sensory cortical areas. Here, We used this behavioral paradigm of "incidental cue" and event-related fMRI to investigate whether there were a privileged WM state and top-down modulation for complex stimuli including faces and natural scenes. We found that faces, not scenes, could enter into the privileged state with improved accuracy and response time of WM task. Meanwhile, cue-driven baseline activity shifts in fusiform face area (FFA) were identified by univariate analysis in the recognition of privileged faces, compared to that of non-privileged ones. In addition, the functional connectivity between FFA and right inferior frontal junction (IFJ), middle frontal gyrus (MFG), inferior frontal gyrus, right intraparietal sulcus (IPS), right precuneus and supplementary motor area was significantly enhanced, corresponding to the improved WM performance. Moreover, FFA connectivity with IFJ and IPS could predict WM improvements. These findings indicated that privileged WM state and potential top-down modulation existed for faces, but not scenes, during WM maintenance period.
自上而下的调制在工作记忆（WM）的多个阶段发挥作用，包括预期、编码和维持。在WM维持期间，一个“偶然线索”可以使两个项目中的一个进入优先状态，并使优先项目被更精确地回忆起来，尽管该线索与被探测为目标的项目无关。关于WM的不同表征状态，尚不清楚在感觉皮层区域是否存在自上而下的调制。在这里，我们使用这种“偶然线索”的行为范式和事件相关功能磁共振成像来研究对于包括面孔和自然场景在内的复杂刺激，是否存在优先的WM状态和自上而下的调制。我们发现，面孔而非场景能够以更高的WM任务准确性和反应时间进入优先状态。同时，与非优先面孔相比，在识别优先面孔时，通过单变量分析确定了梭状面孔区（FFA）中线索驱动的基线活动变化。此外，FFA与右下额叶交界处（IFJ）、额中回（MFG）、额下回、右顶内沟（IPS）、右楔前叶和辅助运动区之间的功能连接显著增强，这与WM表现的改善相对应。此外，FFA与IFJ和IPS的连接可以预测WM的改善。这些发现表明，在WM维持期间，面孔存在优先的WM状态和潜在的自上而下的调制，而场景则不存在。
