Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Wales, UK.
Hum Brain Mapp. 2019 Jul;40(10):2884-2898. doi: 10.1002/hbm.24566. Epub 2019 Mar 13.
Precuneus/posterior cingulate cortex (PCu/PCC) are key components of a midline network, activated during rest but also in tasks that involve construction of scene or situation models. Despite growing interest in PCu/PCC functional alterations in disease and disease risk, the underlying neurochemical modulators of PCu/PCC's task-evoked activity are largely unstudied. Here, a multimodal imaging approach was applied to investigate whether interindividual differences in PCu/PCC fMRI activity, elicited during perceptual discrimination of scene stimuli, were correlated with local brain metabolite levels, measured during resting-state H-MRS. Forty healthy young adult participants completed an fMRI perceptual odd-one-out task for scenes, objects and faces. H-MRS metabolites N-acetyl-aspartate (tNAA), glutamate (Glx) and γ-amino-butyric acid (GABA+) were quantified via PRESS and MEGA-PRESS scans in a PCu/PCC voxel and an occipital (OCC) control voxel. Whole brain fMRI revealed a cluster in right dorsal PCu/PCC that showed a greater BOLD response to scenes versus faces and objects. When extracted from an independently defined PCu/PCC region of interest, scene activity (vs. faces and objects and also vs. baseline) was positively correlated with PCu/PCC, but not OCC, tNAA. A voxel-wise regression analysis restricted to the PCu/PCC H-MRS voxel area identified a significant PCu/PCC cluster, confirming the positive correlation between scene-related BOLD activity and PCu/PCC tNAA. There were no correlations between PCu/PCC activity and Glx or GABA+ levels. These results demonstrate, for the first time, that scene activity in PCu/PCC is linked to local tNAA levels, identifying a neurochemical influence on interindividual differences in the task-driven activity of a key brain hub.
楔前叶/后扣带回皮层（PCu/PCC）是中线网络的关键组成部分，在休息时激活，但也在涉及场景或情境模型构建的任务中激活。尽管人们对 PCu/PCC 在疾病和疾病风险中的功能改变越来越感兴趣，但 PCu/PCC 任务诱发活动的潜在神经化学调节剂在很大程度上仍未得到研究。在这里，采用多模态成像方法来研究在场景刺激的感知辨别过程中，PCu/PCC 的 fMRI 活动的个体间差异是否与静息状态下 1 H-MRS 测量的局部脑代谢物水平相关。40 名健康年轻成年参与者完成了场景、物体和面孔的 fMRI 感知异类任务。通过 PRESS 和 MEGA-PRESS 扫描在 PCu/PCC 体素和枕叶（OCC）对照体素中定量了 N-乙酰天冬氨酸（tNAA）、谷氨酸（Glx）和γ-氨基丁酸（GABA+）代谢物。全脑 fMRI 显示右背侧 PCu/PCC 中存在一个簇，该簇对场景的 BOLD 反应大于对脸和物体的反应。当从一个独立定义的 PCu/PCC 感兴趣区域中提取出来时，场景活动（与脸和物体以及与基线相比）与 PCu/PCC 呈正相关，但与 OCC 不相关。将回归分析限制在 PCu/PCC 1 H-MRS 体素区域，确定了一个显著的 PCu/PCC 簇，证实了与场景相关的 BOLD 活动与 PCu/PCC tNAA 之间的正相关。PCu/PCC 活动与 Glx 或 GABA+水平之间没有相关性。这些结果首次表明，PCu/PCC 中的场景活动与局部 tNAA 水平相关，确定了对关键大脑中枢的任务驱动活动中个体间差异的神经化学影响。
