老化对视觉注意调控网络的影响

Effects of Aging on Visual Attention Regulatory Network

目的老龄化是日益严重的社会性问题。老年人的认知功能,如注意等,出现了明显的衰退。探究老化过程中视觉注意调控网络的改变有助于理解老年人认知功能衰退的神经机制,并为寻找潜在的干预方式提供理论基础。方法本研究采用经典的双目标注意任务:被试仅需全程注视屏幕中心的黑十字。黑十字左右两侧13.5°视角度会呈现两个相同的视觉圆点,800~1200 ms后其中随机一个目标会发生改变或者不变。通过采集该视觉注意任务期间的脑电活动信号,比较青年人与老年人在视觉目标改变和不变两种条件下的大脑活动。结果实验发现在青年人中,额叶、顶叶和颞叶等脑区的电极记录到的神经电活动特征对视觉目标是否改变存在显著性差别,而老年人的脑活动对该视觉目标改变无显著性变化。此外,还发现该脑网络的变化在青年人和老年人中均存在性别差异。结论注意任务下老年人脑网络难以对外界视觉信息输入做出及时响应,老化过程伴随视觉注意调控网络(额叶、顶叶和颞叶等)功能的衰退,该脑网络的变化存在性别差异。本研究为老化引起视觉注意调控网络损伤提供了新的证据。

Objective Aging is an increasingly serious social problem.The cognitive function of the elderly,such as attention,shows a significant decline.Investigating the deficits of visual attention regulatory network caused by aging will further our understanding of the neural mechanism of cognition declines of the elderly,and providing us the theoretical basis to find potential intervention methods.Methods In the study,we used a classical two-target attention task.Subjects were asked to keep their gaze on the central fixation cross,a pair of spots appeared separately located on left and right 13.5°from the cross.After 800-1200 ms fixation,one of the two spots randomly changed its form or both remained unchanged.We recorded neural activity of young adults and old adults during the attention task using electroencephalogram(EEG).Results Through comparing the differences of EEG activity under visual stimuli changed and unchanged conditions,we found that neural activity of channels in frontal,parietal and temporal areas of young adults significantly changed with the change of stimuli,while neural activity of old adults didn't follow the change of stimuli.Conclusion These results demonstrated that brain network of the elderly could not effectively react to the change of external visual information load in the attention task.Aging is accompanied by the functional decline of the visual attention regulatory network.Besides,decline of this brain network also showed sex difference.Our research provided new evidence for the decline of visual attention regulatory network of the elderly.