ROI analysis
As we just completed a group-level analysis, and identified some regions of the brain show a significant difference under the condition of the experiment. Now, we are going to continue our learning with region of analysis(ROI). This is called a whole-brain or exploratory analysis. When we doesn’t have a hypothesis to test, these types of studies are beneficial.
While a large number of studies have been run about a specific topic, we can begin to make more specific hypotheses about where we should find our results in the brain images. For instance, memory has been studied for many years, and many fMRI studies have been published about it using different paradigms that compare differenmt memory tasks. In general, significant increases in the BOLD signal during various memories conditions are seen in a region of the brain known as the Hippocampus and medial temporal lobe. For this BART study, then, we could restrict our analysis to this region and only extract data from voxels within that region. This is known as a ROI analysis. In short, a general name for an analysis in which we choose to analyze a region selected before look at whole-brain results is called a confirmatory analysis.
In terms of BART study, Whole-brain maps can hide important details about the effects that we’re studying. As you may find a significant effect of BART conditions, but the reason the effect is significant could come from a greater change of cash than explode, or because explode is much more negative than cash, or some combination of the two. The only way to determine what is driving the effect is with ROI analysis, and this is especially important when