Center of Brain and Cognition, Theoretical and Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona, Spain.
Neuroimage. 2012 Sep;62(3):1342-53. doi: 10.1016/j.neuroimage.2012.06.007. Epub 2012 Jun 13.
A growing body of experimental evidence suggests that functional connectivity at rest is shaped by the underlying anatomical structure. Furthermore, the organizational properties of resting-state functional networks are thought to serve as the basis for an optimal cognitive integration. A disconnection at the structural level, as occurring in some brain diseases, would then lead to functional and presumably cognitive impairments. In this work, we propose a computational model to investigate the role of a structural disconnection (encompassing putative local/global and axonal/synaptic mechanisms) on the organizational properties of emergent functional networks. The brain's spontaneous neural activity and the corresponding hemodynamic response were simulated using a large-scale network model, consisting of local neural populations coupled through white matter fibers. For a certain coupling strength, simulations reproduced healthy resting-state functional connectivity with graph properties in the range of the ones reported experimentally. When the structural connectivity is decreased, either globally or locally, the resultant simulated functional connectivity exhibited a network reorganization characterized by an increase in hierarchy, efficiency and robustness, a decrease in small-worldness and clustering and a narrower degree distribution, in the same way as recently reported for schizophrenia patients. Theoretical results indicate that most disconnection-related neuropathologies should induce the same qualitative changes in resting-state brain activity.
越来越多的实验证据表明，静息状态下的功能连接受潜在解剖结构的影响。此外，静息态功能网络的组织特性被认为是实现最佳认知整合的基础。如果结构水平上出现连接中断，如某些脑部疾病中发生的那样，那么就会导致功能，可能还会导致认知障碍。在这项工作中，我们提出了一个计算模型来研究结构连接中断（包括局部/全局和轴突/突触机制）对新兴功能网络的组织特性的影响。使用一个由局部神经元群体通过白质纤维耦合而成的大规模网络模型，模拟了大脑的自发神经活动和相应的血液动力学反应。在一定的耦合强度下，模拟再现了具有实验报道的范围内图性质的健康静息状态功能连接。当结构连接无论是全局还是局部减少时，模拟得到的功能连接表现出网络重组的特征，表现为层次结构、效率和鲁棒性的增加，小世界特性和聚类的减少，以及度分布变窄，与最近报告的精神分裂症患者的情况相同。理论结果表明，大多数与连接中断相关的神经病理学应该会导致静息态大脑活动发生相同的定性变化。
