Laboratory of Brain and Cognition, National Institute of Mental Health/NIH, Bethesda, MD 20892, USA.
Neuroimage. 2010 Jan 1;49(1):401-14. doi: 10.1016/j.neuroimage.2009.07.051. Epub 2009 Jul 29.
An increasing number of fMRI studies are using the correlation of low-frequency fluctuations between brain regions, believed to reflect synchronized variations in neuronal activity, to infer "functional connectivity". In studies of autism spectrum disorder (ASD), decreases in this measure of connectivity have been found by focusing on the response to task modulation, by using only the rest periods, or by analyzing purely resting-state data. This difference in connectivity, however, could result from a number of different mechanisms--differences in noise, task-related fluctuations, task performance, or spontaneous neuronal activity. In this study, we investigate the difference in functional connectivity between adolescents with high-functioning ASD and typically developing control subjects by examining the residual fluctuations occurring on top of the fMRI response to an overt verbal fluency task. We find decreased correlations of these residuals (a decreased "connectivity") in ASD subjects. Furthermore, we find that this decrease was not due to task-related effects, block-to-block variations in task performance, or increased noise, and the difference was greatest when primarily rest periods are considered. These findings suggest that the estimate of disrupted functional connectivity in ASD is likely driven by differences in task-unrelated neuronal fluctuations.
越来越多的 fMRI 研究采用脑区之间低频波动的相关性来推断“功能连接”，这种相关性被认为反映了神经元活动的同步变化。在自闭症谱系障碍（ASD）的研究中，通过关注对任务调节的反应、仅使用休息期或分析纯粹的静息状态数据，发现了这种连接性的降低。然而，这种连接性的差异可能是由于许多不同的机制造成的——噪声、与任务相关的波动、任务表现或自发神经元活动的差异。在这项研究中，我们通过检查在明显言语流畅性任务的 fMRI 反应之上发生的剩余波动，来研究高功能 ASD 青少年与典型发育对照受试者之间的功能连接差异。我们发现 ASD 受试者的这些残差（连接性降低）的相关性降低。此外，我们发现这并不是由于与任务相关的影响、任务表现的块间变化或噪声增加所致，当主要考虑休息期时，差异最大。这些发现表明，ASD 中功能连接中断的估计可能是由与任务无关的神经元波动差异驱动的。
