健康与遗传心理学研究室知识库

    目前，视觉空间注意的心理过程和神经基础还不十分清楚，空间注意在信息加工过程中所起的作用也未彻底明确。Eriksen等提出的空间注意“变焦镜”理论认为视觉注意是一个资源有限的系统，它可以指向一定大小的空间区域，增加注意的空间区域可以使注意的资源在更大的区域内分配。本研究采用不同空间范围的“提示—目标”实验范式，以正常青年人为研究对象，对不同注意范围提示及其在干扰条件下对视觉空间注意的影响，进行了系列的事件相关脑电位(ERP)实验和行为学实验，从不同方面得到了关于视觉空间注意范围早期调控脑机制的行为数据和电生理学证据，并探讨了视觉空间注意的年老化问题。结果如下:
    ①当给予不同等级的空间提示时，随着提示范围的减小，反应时加快，早期P1与N1波幅增大，表明“变焦镜”效应发生在信息加工的早期阶段; P1提示效应与P2效应分离，揭示注意的提示范围扩大，需要更多的加工资源;P2效应的左右半球分离，提示左半球是提示下注意加工的优势半球。
    ②在固定提示范围的视觉搜索条件下，靶刺激位置对视觉P1和Nl等ERP早期成分未产生显著影响。即视觉ERP早期成分(头皮后部P1和Nl )所代表的早期视皮质活动不受靶刺激位置的调节。
    ③干扰刺激引起后部Pl和前部N1波幅增大以及前部P2潜伏期延长;内部干扰的影响还表现在中线和右半球的P2波幅受到明显抑制，对靶刺激识别的影响大于外部干扰。
    ④汉字提示和范围提示下ERP等级效应具有不同的表现形式;与范围提示相比，汉字提示下的靶刺激引起后部P1、前部P2的增强和后部N1的抑制。范围提示能够加快靶刺激识别或视觉搜索的速度，在外部干扰条件下，范围提示的靶刺激识别速度优势更为突出;
    ⑤干扰刺激与靶刺激相对位置的变化对靶刺激搜索有显著影响，表现为干扰在对侧小圈即距靶刺激较近时，后部P1增强和N1的减小存在提示注意范围等级对干扰刺激影响的早期ERP成分变化，且外部干扰和内部干扰有各自的特点，在内部干扰时表现为干扰一靶刺激距离越近，后部P1增强和N1减小，而在外部干扰时，干扰一靶刺激距离越近，反应时越长，前部N1减小和P2增强。
    ⑥年老化引起视觉空间注意(随意注意和反射性注意)功能的降低;视觉加工的最早期阶段受到了年老化的影响，源于外纹状皮质的后部P1显  著增大;年老化引起前部P:成分的显著抑制不口波形的不稳定，提示前    额叶功能缺陷可能是视觉空间注意障碍的主要原因;内部干扰下年老化对ERP早期成分的影响程度更大，与年老化的“复杂度效应”一致。
综上所述，本研究的结果显示不同注意范围、不同干扰条件以及年老化对前部N1和P2的不同影响，反映了前额区在视觉空间注意中具有重要作用，因而是对Where通道理论的有益补充;本研究结果也支持Eriksen等提出的空间注意“变焦镜”理论，而视觉空间注意的干扰机制则是对“变焦镜”理论的进一步发展。

    At present, the psychological process and neural correlates of visual spatial attention is still not clear, and the role of visual spatial attention in information processing is still to be clarified. The "zoom-lens" theory about spatial attention put forward by Eriksen et al holds that the visual attention is a system with limited resources. It can be directed to a certain spatial region, and increasing the spatialattention region can enlarge the distribution area of attention resources.
    The even-related potentials (ERPs) and behavioral experiments were carried out using a "cue-target" paradigm precued by the different spatial regions in the young and old people. The goal of the present experiment is to the study neural basis of different scales of regions as well as different conditions of interference on visual spatial attention. The  behavioral  data and electrophysiological results on the early dynamic mechanisms of visual attention were as the following:
    (1) The faster for the reaction time, the larger in the amplitude of early ERP component P1 and N1, and the smaller with the cue scale. This suggests that "zoom-lens effect" took place at the early stage of information processing. The P 1 and P2 effect separated, means the cue effect enhanced, and the additional computation was needed. The left and right sphere of P2 effect separated, which indicated the left hemisphere predominated in the attention processing under cue.
    (2) Under the condition of fixed cue region, the location of targets did not significantly affect the early ERP component of the P1 and N1. That is, the early visual cortical activities represented by the P1 and N1 were not regulated by the target location.
    (3) Interference enlarged the amplitude of the posterior P1，the anterior N 1 and prolonged the latency of the anterior P2; the effects of endogenous interference were also manifested by the obvious inhibition of P2 amplitude in the medline area and the right hemisphere. The affection of the interior interference on the target discrimination was bigger than of the interior interference.
    (4) The scales effects of ERP under semantic cue and region cue had different forms;compared with that in region cue, target stimulation in semantic cue could lead to the increase of posterior Pl, the decrease of N1 and the increase of P2. Region cue could make target discrimination faster; what's more, with exterior interference, the speed superiority in target stimulation discrimination on region cue was much more outstanding.
    (5) The change in the relative position between interference stimulation and target stimulation could have significant effect on target discrimination, and there was early ERP component effect, which indicated the scale effect of attention on interference stimulation, and exterior interference and interior interference had their different features. In case of interior interference, the nearer the interference to the target, the larger the posterior P 1  amplitude and the smaller the posterior N 1 amplitude; while in case of exterior interference, the nearer the interference to the target, the longer the reaction time, the smaller the anterior N1 amplitude and the larger the anterior P2 amplitude;
    (6) Aging could lead to the decrease in the function of visual spatial attention (voluntary and involuntary); The earliest stage of visual analysis was affected by aging, which originated from the obvious increase of posterior P1 in extrastriate cortical areas; Aging resulted in the dysfunction of prefrontal areas in visual spatial attention----the obvious inhibition of anterior P2 and the instability in its wave. Under interior interference, aging had more effect on the early element of ERP which was consistent with  "complexity effect" of aging.
    In conclusion, different attention scale, different interference condition and the different effects of aging on anterior N1 and P2 proved the important role of prefrontal area in visual spatial attention, which further developed the "Where Pathway”Theory. The results of the interference-free experiments in the research could support the "zoom-lens”theory in spatial attention which was put forward by Eriksen et al, but the interference mechanisms of visual spatial attention were a beneficial supplement for "zoom-lens”theory.