不同持续时间的短暂视觉刺激引起的BOLD响应在初级皮层区的时间特性

目的探讨在短暂视觉刺激情况下,大脑初级视觉皮层(V1)的血氧水平依赖(BOLD)性响应的时间特性.材料与方法采用事件关联型磁共振功能成像(ER-fMRI)技术,通过改变视觉刺激的持续时间,即从Is到6s,检测BOLD响应的峰值、基线之上的面积、响应恢复到基线的时间、达到峰值的时间等特征值的变化,评估BOLD响应的测量值和预测值之间的关系.结果作为视觉刺激时间的函数,BOLD响应曲线的峰值、基线之上的面积、响应恢复到基线的时间、达到峰值的时间等呈直线增加.对于所有刺激时间,BOLD响应的预测值全部大于测量值.结论在短暂刺激时,视觉刺激时间与BOLD响应之间是非线性关系.但当研究其引起的神经活动时,BOLD响应的峰值、基线之上的面积、响应恢复时间和峰值时间可以是重要的参考值.

Temporal Characteristics of BOLD Response to Brief Visual Stimuli of Varying Duration in Human V1

Purpose: To investigate the temporal characteristics of BOLD responses to brief visual stimulation of the human primary visual cortex (V1). Materials and Methods: Using ER fMRI technique the magnitude and extent of the BOLD reponse were examined by changing the stimulus duration of a reversing checkerboard between 1 to 6s. The relationship between measured and predicted BOLD responses was also evaluated. Results: The peak hight, area above the baseline, width of the response and peak time increased linearly as a function of stimulus duration. It was also shown that the predicted response was over estimated the measured response. Conclusion: BOLD response exhibits nonlinear behavior, but the peak height, area, width and peak time of the BOLD response may be important parameters when studying the neural activation resulting from brief visual stimuli.