分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Rao, Jia-Sheng
Zhao, Can
Liu, Zuxiang
Yang, Zhao-Yang
Li, Xiao-Guang
Ma, Manxiu
Liu, Zuxiang
Yang, Zhao-Yang
Li, Xiao-Guang
摘要： Purpose: To investigate the longitudinal brain regional homogeneity (ReHo) changes in nonhuman primate after spinal cord injury (SCI) by resting-state functional magnetic resonance imaging (fMRI). Methods: Three adult female rhesus monkeys underwent unilateral thoracic cord injury. A resting-state fMRI examination was performed in the healthy stage and 4, 8, and 12 weeks after the injury. The ReHo value of each voxel in the monkey brain was calculated and compared between pre- and post-SCI monkeys with paired t test. The regions of interest (ROIs) in the significantly changed ReHo regions were set. The correlations between the ReHo change and the time after injury were also determined. Results: Compared with those in healthy period, the ReHo values of the left premotor cortex and the anterior cingulate cortex (ACC) in post-SCI rhesus monkeys significantly increased in 4-week follow-up examinations. The ReHo values of posterior cingulate cortex, left precuneus, left temporal parietooccipital area, and bilateral superior parietal lobules decreased at 8-week follow-up examinations. In 12-week follow-up examinations, the ReHo values of the left postcentral gyrus, right caudate nucleus, and superior temporal gyrus increased. Correlation analysis showed positive correlations between left ACC and the postoperative time. Conclusion: SCI can change the regional synchronism of brain activity in sensorimotor system and the default mode network. These findings may help us to understand the potential pathophysiological changes in the central nervous system after SCI. (C) 2015 Elsevier Inc. All rights reserved.
分类： 生物学 >> 生物物理学 >> 神经科学 提交时间： 2016-05-11
Wu, Qiong
Xi, Sisi
Wu, Yanhong
Chang, Chi-Fu
Huang, I-Wen
Juan, Chi-Hung
Liu, Zuxiang
Wu, Yanhong
Wu, Yanhong
Fan, Jin
Fan, Jin
Fan, Jin
Fan, Jin
摘要： Information processing can be biased toward behaviorally relevant and salient stimuli by top-down (goal-directed) and bottom-up (stimulus-driven) attentional control processes respectively. However, the neural basis underlying the integration of these processes is not well understood. We employed functional magnetic resonance imaging (fMRI) and transcranial direct-current stimulation (tDCS) in humans to examine the brain mechanisms underlying the interaction between these two processes. We manipulated the cognitive load involved in top-down processing and stimulus surprise involved in bottom-up processing in a factorial design by combining a majority function task and an oddball paradigm. We found that high cognitive load and high surprise level were associated with prolonged reaction time compared to low cognitive load and low surprise level, with a synergistic interaction effect, which was accompanied by a greater deactivation of bilateral temporoparietal junction (TPJ). In addition, the TPJ displayed negative functional connectivity with right middle occipital gyrus, which is involved in bottom-up processing (modulated by the interaction effect), and the right frontal eye field (FEF), which is involved in top-down control. The enhanced negative functional connectivity between the TPJ and right FEF was accompanied by a larger behavioral interaction effect across subjects. Application of cathodal tDCS over the right TPJ eliminated the interaction effect. These results suggest that the TPJ plays a critical role in processing bottom-up information for top-down control of attention. Hum Brain Mapp 36:4317-4333, 2015. (c) 2015 Wiley Periodicals, Inc.
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