Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States of America.
PLoS One. 2012;7(8):e39804. doi: 10.1371/journal.pone.0039804. Epub 2012 Aug 3.
The corpus callosum is hypothesized to play a fundamental role in integrating information and mediating complex behaviors. Here, we demonstrate that lack of normal callosal development can lead to deficits in functional connectivity that are related to impairments in specific cognitive domains. We examined resting-state functional connectivity in individuals with agenesis of the corpus callosum (AgCC) and matched controls using magnetoencephalographic imaging (MEG-I) of coherence in the alpha (8-12 Hz), beta (12-30 Hz) and gamma (30-55 Hz) bands. Global connectivity (GC) was defined as synchronization between a region and the rest of the brain. In AgCC individuals, alpha band GC was significantly reduced in the dorsolateral pre-frontal (DLPFC), posterior parietal (PPC) and parieto-occipital cortices (PO). No significant differences in GC were seen in either the beta or gamma bands. We also explored the hypothesis that, in AgCC, this regional reduction in functional connectivity is explained primarily by a specific reduction in interhemispheric connectivity. However, our data suggest that reduced connectivity in these regions is driven by faulty coupling in both inter- and intrahemispheric connectivity. We also assessed whether the degree of connectivity correlated with behavioral performance, focusing on cognitive measures known to be impaired in AgCC individuals. Neuropsychological measures of verbal processing speed were significantly correlated with resting-state functional connectivity of the left medial and superior temporal lobe in AgCC participants. Connectivity of DLPFC correlated strongly with performance on the Tower of London in the AgCC cohort. These findings indicate that the abnormal callosal development produces salient but selective (alpha band only) resting-state functional connectivity disruptions that correlate with cognitive impairment. Understanding the relationship between impoverished functional connectivity and cognition is a key step in identifying the neural mechanisms of language and executive dysfunction in common neurodevelopmental and psychiatric disorders where disruptions of callosal development are consistently identified.
胼胝体被假设在整合信息和调节复杂行为方面发挥着基本作用。在这里，我们证明了正常胼胝体发育的缺乏会导致功能连接的缺陷，而这些缺陷与特定认知领域的损伤有关。我们使用脑磁图成像（MEG-I）检查了胼胝体发育不全（AgCC）个体和匹配对照组在 alpha（8-12Hz）、beta（12-30Hz）和 gamma（30-55Hz）频段的静息状态功能连接。全局连接（GC）被定义为一个区域与大脑其他部分之间的同步。在 AgCC 个体中，alpha 频段的 GC 在背外侧前额叶（DLPFC）、后顶叶（PPC）和顶枕叶皮质（PO）中显著降低。在 beta 或 gamma 频段中，GC 没有显著差异。我们还探讨了这样一种假设，即在 AgCC 中，这种功能连接的区域减少主要是由于半球间连接的特定减少。然而，我们的数据表明，这些区域连接的减少是由半球间和半球内连接的错误耦合驱动的。我们还评估了连接程度是否与行为表现相关，重点关注在 AgCC 个体中受损的认知测量。AgCC 参与者的左内侧和上颞叶的静息状态功能连接与神经心理学言语处理速度测量显著相关。AgCC 队列中 DLPFC 的连接与塔伦卢尔任务的表现密切相关。这些发现表明，异常的胼胝体发育会产生显著但选择性的（仅 alpha 频段）静息状态功能连接中断，与认知障碍相关。了解功能连接不良与认知之间的关系是识别常见神经发育和精神障碍中语言和执行功能障碍的神经机制的关键步骤，在这些障碍中，胼胝体发育的中断是一致的。
