Effect of BOLD on Sight Stimulation and Artifact of CSF : Identification of Activating Signal and CSF Artifact

Abstract

This study used functional magnetic resonance imaging (fMRI) for brain function evaluation. fMRI data were collected by a block paradigm, and brain function was evaluated. In the block paradigm, the BOLD effect causes a several-second delay in hemodynamics, and analytical processing is done in consideration of this time lag. However, irrelevant artifacts caused by the BOLD effect frequently occur in analytical processing. Therefore, there is a limit to obtaining a sufficient activating reaction in the analytical system, which is normally equipped with MRI. Thus, obtaining the activating reaction is limited because the corresponding misregistration correction, angle correction, time series correction, and so on, are insufficient in an analytical system equipped with MRI. It has become standard to use analytical systems such as SPM. We examined the mean curve of the activating part and the area of artifact. As a result, it was possible to identify the activating signal and the artifact signal, and it became possible to obtain an adequate response from a system that is normally equipped with an activating signal in which artifacts are few.