汉字提示下视空间注意年老化的事件相关电位研究

目的：采用“提示-目标”的视觉实验范式,以汉字提示不同等级的搜索范围,通过事件相关电位(ERP)技术研究早期视觉注意年老化脑机制。方法：以青年和老年人各16名为被试,背景由3个同心圆组成,提示为汉字“大”、“中”、“小”,刺激材料是随机选取的大写英文字母,组成3个同心圆圈。“T”为靶刺激,被试按照提示搜索提示范围上的靶刺激。结果：与青年组相比,老年组反应时更长：老年组后部P1显著增强和N1明显抑制;老年组前部P2成分受到显著抑制,这种抑制不仅表现在波幅上,还表现在波形的不规则和不稳定。结论：年老化引起视觉空间随意注意功能的降低,其视觉分析的最早期阶段亦受到年老化的影响,而且老年组被试对靶刺激的评估识别能力降低,提示年老化可能导致视觉空间随意注意的前脑区功能缺陷,

Aging Study of Event-related Potential on Visual Spatial Attention Precued by Chinese Words

Objective: Based on the visual experimental paradigm "precue-target", the search range should be affected by different Chinese characters and the dynamic mechanisms of aging in the brain on the visual attention were investigated. Method: 16 young and 16 old subjects participated the experiment. Cue was comprised of three Chinese words "Large", or "Median" or "Small." The letter "T" was designed as the target stimulus. When the cue was the "large", "T" may appear within 3 circles. When the cue was the "median", "T" may appear within either the median and small circles. When the cue was small, the target "T" may appear only within the small circle. Result: The reaction time (RT) of the two groups of subjects became quick with the reduction of the cue size, while amplitudes of the P1 and N1 component of ERPs increased with the decrease of the cue scale. Old subjects showed longer RT than younger subjects did. The posterior P1 was enhanced significantly and the N1 was inhibited obviously in the old group. The P2 was manifested as significantly inhibitory effect not only in the amplitude but also in the abnormal and unstable waveform. Conclusion: The cognitive function of elderly subjects declined in the task of visual spatial attention. We demonstrated for the first time that the P2 was manifested as significantly inhibitory effect, which suggested that the age-related reduction could lead to dysfunction in the anterior scalp to visual spatial attention (voluntary attention).