We use MRI images of brain anatomy in several ways. First, we coregister our EROS, NIRS and ERP data to each subjects MRI brain image in order to accurately determine which brain structures are being measured. We also make quantitative measurements of the size of various brain structures to see how their variation across subjects correlates with both behavior and with optical and electrical responses. In addition we are exploring the use of Diffusion Tensor Imaging (DTI) to trace fiber tracts in the brain, which can be compared to the functional connectivity maps derived from EROS measurements. Finally, we are investigating the utility of using MRI images to model the optical properties of each subject's head and brain in order to improve the spatial localization and resolution of optical measurements.
Functional Magnetic Resonance Imaging is an established technique which provides images with very good spatial resolution (0.5 cm or less) and has a temporal resolution of the order of .5 to 5 seconds, depending on the situation. Thus, whereas its temporal resolution is inferior to that of ERPs and EROS, the spatial information it provides is excellent. For this reason, MRI and fMRI provide data that effectively compliments that from optical measurements.
