Analyzing Method of Temporal Brain Activation in fMRI Measurements

Abstract

AbstractIn this paper, we propose a method to acquire the temporal changes of activations by combining a slide of the analysis time window and t‐value. An advantage of this method is that it can acquire rough changes of the activated areas even with data having low time resolution. Nine normal subjects participated in the study of the visual oddball paradigm, which consisted of a random series of 30 targets and 30 control stimuli. Here, the subjects were instructed to push a button as the go‐task when a target stimulus occurred. We investigated the activated area in three types of analysis time sections: from stimulus onset to 5 s after the stimulus (time section A; TS‐A); from 5 to 10 s (TS‐B); and from 10 to 15 s (TS‐C). We also investigated the temporal change of the t‐value between go and no‐go responses in blood oxygenation level dependent (BOLD) signals. In this study, we picked up the following eight representative areas corresponding with previous reports: left primary motor area and left somatosensory motor area, supramarginal gyri (SMG), right superior parietal lobule, right inferior frontal gyrus, cerebellum (cerebellar tonsil), and right medial frontal gyrus. Among them, the left primary motor area and left somatosensory motor area showed prominent activation (t > 10) in TS‐A and TS‐B, respectively. Activity at the left supramarginal gyrus decreased gradually with time, and right insula showed constant activation through all time sections.We could see various patterns on temporal activation at different positions in the brain. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.