摘要目的 探索视觉工作记忆的电生理变化特点及其容量限制问题. 方法 应用多通道事件相关电位(ERP)技术,采用延迟样本匹配任务观察18名志愿受试者在5种刺激阵列[(组成2个项目(2 items)、3个项目(3 items)、4个项目(4 items)、6个项目(6 items)和9个项目(9 items)]下诱发的ERP的变化特点,并利用ERP数据t值的统计参数影像(SPM)呈现其脑电地形图,对其时空模式进行分析. 结果 (1)在记忆阵列开始呈现约400 ms时,于双侧后顶部和侧枕部电极位置上有一个大的负走向电位(负向慢波),该波随着刺激阵列从2 items、3 items到4items的增加其波幅增高逐渐明显,但当刺激阵列增加达到6 items、9 items时,其波幅不但不再增加,反而有回退的趋势,这种反应持续于整个记忆保留阶段;各刺激阵列的波幅均值是不完全相同的,总体比较差异有统计学意义(P＜0.05).(2)受试者的配对t检验结果显示,3 items与2 items之间比较的t值的SPM显示显著效应主要发生在双侧枕顶区(450～800 ms),4 items与2 items之间比较的t值的SPM显示显著效应主要发生在双侧枕顶区(350～990 ms). 结论 视觉记忆刺激在顶枕部诱发出的负向慢波反映了视觉工作记忆的记忆保持,其存在容量限制,且与容量相关的脑功能区可能在顶枕部.

abstractsObjective To explore the electro-physiological changes of visual working memory (WM) and the issues related to its capacity limitation.Methods Delayed sample matching duty was used to observe the characteristics of event-related potential (ERP) changes of 18 participants under the evoking of 5 types of stimuli items (consisting of stimulus arrays:2 items,3 items,4 items,6 items and 9 items).The results of ERP analysis were presented by statistical parametric mapping (SPM) oft value.Results At the presentation of 400 ms of memory array,a big negative slow wave was observed in bilateral posterior parietalis and lateral occipitalia,and its amplitude increased gradually with the number of stimulus items increasing from 2 to 4,reaching to the maximum at 4 items; and then,it started to decrease when the number increased to 6 and 9; this reaction lasted for the entire memory retention phase;the amplitude of each array was not totally the same,with significant difference (P＜0.05).The SPM(t)results of ERP showed significant effects in bilateral parietal-occipital sites at 450-800 ms (between 3 and 2 items) and 350-990 ms (between 4 and 2 items).Conclusion Negative slow waves evoked by visual memory stimula in parietal-occipital site reflect the memory retention of visual WM.There is a limitation in visual WM capacity,and functional sites of brain related to its limitation of capacity may locate in the parietal-occipital sites.