Influence of Spontaneous BOLD Fluctuation on Stimulus-Evoked BOLD in Human Visual Cortex Using Event-Related Paradigm

Xiao Liu¹, Xiao-Hong Zhu¹, Wei Chen¹

This study found that the spontaneous BOLD fluctuations account for the trial-to-trial variation of stimulus-evoked BOLD responses in human visual cortex, and thus confirmed the linear superimposition of spontaneous BOLD fluctuation and stimulus-evoked BOLD signal in the event-related fMRI studies. Combined with the results from one previous study using continuous visual stimulation, it also suggested that the instantaneous stimuli used by the event-related studies could probably only perturb the spontaneous brain activity briefly and slightly, and thus result in the linear superimposition of BOLD signals approximately, which however could not hold when continuous stimuli are used to constantly stimulate the brain.