位置提示与汉字提示视觉注意范围的脑机制差异

目的：研究并比较在位置提示与汉字提示下注意范围对脑内时程变化影响的异同，探讨视觉注意范围加工的脑机制。方法：实验一使用固定位置的、3种不同直径的线圈作为注意范围的位置性提示，实验二使用汉字来提示注意范围的大小。结果：在短时间间隔（ISI）条件、小和中范围时，实验一的反应时要显著小于实验二。在同等提示条件下，两实验提示物诱发的ERP相比较：实验二前部N1波幅显著大于实验一，实验二后部P1潜伏期长于实验一；两实验靶刺激诱发的ERP相比较：实验二后部P1、N1成分的潜伏期显著长于实验一，实验一后部P2的波幅显著大于实验二。结论：1）汉字提示与位置提示相比，需要更高级脑区的参与，其提示信息较径直地与额叶协同加工；2）前部头颅的N1成分与“top-down“机制及汉字加工影响有关；3）汉字提示信息比位置提示信息引起的注意增益程度小。

Differential Visual Attention Scales Directed by Location Versus Semantic Cue

Objective: To compare the cortical mechanisms associated with visual spatial attention directed by location cues and Chinese character cues. Method: Eleven healthy adults (mean age=19) with normal vision served as the subjects. In experiment I, the cue was a circle with black solid line. There were three cue sizes: small, medium and large. In experiment II, three black concentric circles were presented as background, their diameters were the same as the three cues used in experiment I. The cue was one of three Chinese characters small, medium or large respectively. The task of the subjects was to discriminate the target's orientation. Result: RT in experiment II was longer with short ISI. The anterosuperior N1 amplitude elicited by the cue in experiment II was larger than that in experiment I. The inferoposterior P1 latency in experiment II was longer than that in experiment I. Comparing the target evoked ERP, the inferoposterior P1 and N1, latency of experiment II was longer than that in experiment I, the inferoposterior P2 amplitude in experiment II was larger than that in experiment I. Conclusion: The processing of Chinese cue takes place at higher level functional brain regions compared to processing of location cue. The later requires more resource in the earlier stage of cue process and less in the subsequent stage of the task.