Intro to Analyzing Brain Imaging Data — Part II: Correlation Maps

In the previous article we covered the basics about the data structure and the differences between structural and functional MRI (fMRI). In this article we move on to the analysis of the fMRI data to answer the following question: What brain regions were active during the scan?

This is actually the main objective behind doing a fMRI scan in the first place. While high-resolution MRI scans are performed to get static anatomical insights, fMRI scans aim at getting behind the dynamics of brain functions. In fMRI the blood-oxygen-level dependent (BOLD) signal is recorded by the MRI machine which is an indirect measure of activity within the brain. In order to perform our analysis we first need to understand how the data was acquired. Was there some sort of stimulus, how long was the experiment running, was there a task involved? So basically we need to know the experimental paradigm.

The experimental paradigm

As we already learned in the previous article the dataset we are looking at is from an experiment were the subject was laying in an MRI machine listening to “ bi-syllabic words”. So our expectation is that we should see a modulation of the BOLD signal (the change in blood oxygenation over time) in brain regions involved in auditory processing. To check if this…