背景:全球动态,大脑连通性的状态依赖性重新配置尚不清楚。我们旨在评估全局信号相关系数(GSCORR)的重新配置,每个体素时间序列和全局信号之间的连通性的度量,从静止状态到停止信号任务。次要目的是评估GSCORR与三种不同试验条件下的血氧水平依赖性(BOLD)激活或失活之间的关系(GO,STOP-correct,和STOP-不正确)。
方法:作为主要分析,我们计算了全脑,在107名21-50岁的健康受试者的静息状态(GSCORR-rest)和停止信号任务(GSCORR-task)期间,逐体素GSCORR移位为GSCORR-task减去GSCORR-rest。还对任务剩余时间序列计算了GSCORR-tr和trGSCORR-shift,以量化试验期间任务相关活动的影响。为了测试次要目标,在三种试验条件下,大脑区域首先被分成一组,显示出与任务相关的显著激活,一组显示出显著失活.然后,计算了两个集群中GSCORR-休息/任务/移位与激活/去激活之间的相关性。作为敏感性分析,在执行全局信号回归后,对同一样本计算GSCORR-shift,并且GSCORR-rest/task/shift与任务性能相关。
结果:感觉区和颞顶区表现出负GSCORR偏移。相反,关联区域(即。左舌回,双侧背侧后扣带回,小脑区,丘脑,后外侧顶叶皮质)显示出阳性GSCORR移位(FDR校正p<0.05)。GSCORR偏移显示出与trGSCORR偏移(幅度增加)和全局信号回归(幅度减小)相似的模式。关于大胆的变化,Brodmann6区和下顶叶小叶显示激活,顶叶后小叶,Cuneus,precuneus,额中回显示失活(FDR校正p<0.05)。激活簇中GSCORR-休息/任务/移位和β系数之间没有发现相关性,尽管在GSCORR任务和GO/STOP正确失活之间观察到负相关(Pearsonrho=-0.299/-0.273;Bonferroni-p<0.05)。观察到GSCORR与任务绩效之间的弱关联(未校正的p<0.05)。
结论:GSCORR状态相关重新配置表明在停止信号任务期间将功能资源重新分配到关联区域。GSCORR,激活和去激活可能代表具有特定神经功能相关性的大脑状态的不同代理。
BACKGROUND: The dynamics of global, state-dependent reconfigurations in brain connectivity are yet unclear. We aimed at assessing reconfigurations of the global signal correlation coefficient (GSCORR), a measure of the connectivity between each voxel timeseries and the global signal, from resting-state to a stop-signal task. The secondary aim was to assess the relationship between GSCORR and blood-oxygen-level-dependent (BOLD) activations or deactivation across three different trial-conditions (GO, STOP-correct, and STOP-incorrect).
METHODS: As primary analysis we computed whole-brain, voxel-wise GSCORR during resting-state (GSCORR-rest) and stop-signal task (GSCORR-task) in 107 healthy subjects aged 21-50, deriving GSCORR-shift as GSCORR-task minus GSCORR-rest. GSCORR-tr and trGSCORR-shift were also computed on the task residual time series to quantify the impact of the task-related activity during the trials. To test the secondary aim, brain regions were firstly divided in one cluster showing significant task-related activation and one showing significant deactivation across the three trial conditions. Then, correlations between GSCORR-rest/task/shift and activation/deactivation in the two clusters were computed. As sensitivity analysis, GSCORR-shift was computed on the same sample after performing a global signal regression and GSCORR-rest/task/shift were correlated with the task performance.
RESULTS: Sensory and temporo-parietal regions exhibited a negative GSCORR-shift. Conversely, associative regions (ie. left lingual gyrus, bilateral dorsal posterior cingulate gyrus, cerebellum areas, thalamus, posterolateral parietal cortex) displayed a positive GSCORR-shift (FDR-corrected p < 0.05). GSCORR-shift showed similar patterns to trGSCORR-shift (magnitude increased) and after global signal regression (magnitude decreased). Concerning BOLD changes, Brodmann area 6 and inferior parietal lobule showed activation, while posterior parietal lobule, cuneus, precuneus, middle frontal gyrus showed deactivation (FDR-corrected p < 0.05). No correlations were found between GSCORR-rest/task/shift and beta-coefficients in the activation cluster, although negative correlations were observed between GSCORR-task and GO/STOP-correct deactivation (Pearson rho=-0.299/-0.273; Bonferroni-p < 0.05). Weak associations between GSCORR and task performance were observed (uncorrected p < 0.05).
CONCLUSIONS: GSCORR state-dependent reconfiguration indicates a reallocation of functional resources to associative areas during stop-signal task. GSCORR, activation and deactivation may represent distinct proxies of brain states with specific neurofunctional relevance.