The study on the frontoparietal networks by continuous theta burst stimulation in healthy human subjects

Frontoparietal networks (FPNs) including the regions of the posterior parietal cortex (PPC) and dorsolateral prefrontal cortex (DLPFC) have been implicated in visuospatial attention. However, the functional interactions among different regions of dorsal FPNs remain elusive. The Attention Network Test (ANT) and continuous theta burst stimulation (cTBS) were used to investigate the functional interactions in healthy subjects. During the ANT task, subjects receiving right PPC cTBS responded significantly slower in spatial cue condition, had deficits in both alerting and orienting indices compared with those receiving either the sham cTBS or left PPC cTBS. In addition, subjects receiving left-DLPFC cTBS showed significant improvements on alerting and conflict indices whereas significant deficits on the orienting index compared with those receiving the sham cTBS. Moreover, compared with subjects exposed to the sham cTBS condition, subjects exposed to cTBS to the right-DLPFC exhibited significant decreases in the efficiency of the alerting and conflict indices whereas significant increases in the orienting index. Furthermore, there were significant differences in the alerting, orienting and conflict effect indices between subjects receiving the left-DLPFC-cTBS and those receiving the right-DLPFC-cTBS. These results suggest that the right DLPFC played a pivotal role in executive control process, whereas the right PPC was associated with orienting attentional function. The current study not only supports the model of inter-hemispheric rivalry for visuospatial attention, but also indicates inter-regional competition between the different areas of the FPNs.