Further Evidence of Initial BOLD Dip Across Cortico-Thalamic Visual Network During Visual Stimulation

Nanyin Zhang¹, Xiao-Hong Zhu¹, Yi Zhang¹, Wei Chen¹

The initial dip in the BOLD signal is controversial. In this study we explored the existence and generality of initial dip using a paired-stimulus paradigm. We observed that for the pixels showing initial dip to the first stimulus, they also show obvious initial dip to the second stimulus. The delay between the two dips correlates with the delay between the stimulation pair. Moreover, our study demonstrates that initial dip also exists in sub-cortical brain areas such as thalamus, and suggests the possibility to apply initial dip for functional mapping of the entire cortico-thalamic visual network with improved specificity.