Department of Neurological Surgery, Washington University in St. Louis, St. Louis, MO 63110;
Mallinckrodt Institute Radiology, Washington University in St. Louis, St. Louis, MO 63110.
Proc Natl Acad Sci U S A. 2017 Dec 12;114(50):13278-13283. doi: 10.1073/pnas.1707050114. Epub 2017 Nov 28.
Resting state functional connectivity is defined in terms of temporal correlations between physiologic signals, most commonly studied using functional magnetic resonance imaging. Major features of functional connectivity correspond to structural (axonal) connectivity. However, this relation is not one-to-one. Interhemispheric functional connectivity in relation to the corpus callosum presents a case in point. Specifically, several reports have documented nearly intact interhemispheric functional connectivity in individuals in whom the corpus callosum (the major commissure between the hemispheres) never develops. To investigate this question, we assessed functional connectivity before and after surgical section of the corpus callosum in 22 patients with medically refractory epilepsy. Section of the corpus callosum markedly reduced interhemispheric functional connectivity. This effect was more profound in multimodal associative areas in the frontal and parietal lobe than primary regions of sensorimotor and visual function. Moreover, no evidence of recovery was observed in a limited sample in which multiyear, longitudinal follow-up was obtained. Comparison of partial vs. complete callosotomy revealed several effects implying the existence of polysynaptic functional connectivity between remote brain regions. Thus, our results demonstrate that callosal as well as extracallosal anatomical connections play a role in the maintenance of interhemispheric functional connectivity.
静息态功能连接是根据生理信号之间的时间相关性来定义的，最常使用功能磁共振成像来研究。功能连接的主要特征与结构（轴突）连接相对应。然而，这种关系不是一一对应的。胼胝体的大脑两半球间功能连接就是一个很好的例子。具体来说，有几项研究记录了在胼胝体（大脑两半球之间的主要连合）从未发育的个体中，大脑两半球间功能连接几乎完整。为了研究这个问题，我们在 22 名患有药物难治性癫痫的患者中评估了胼胝体手术前后的功能连接。胼胝体的切开明显降低了大脑两半球间的功能连接。这种效应在额顶叶的多模态联合区比感觉运动和视觉功能的主要区域更为明显。此外，在获得多年纵向随访的有限样本中，没有观察到恢复的证据。部分与完全胼胝体切开的比较显示了几个效应，暗示在远程脑区之间存在多突触功能连接。因此，我们的结果表明，胼胝体以及胼胝体外的解剖连接在维持大脑两半球间功能连接中发挥作用。
