Many of today's most exciting imaging techniques give researchers insight into both brain structure and function. Portraits of the Mind calls this type of imaging tool a mindoscope: "a tool that can probe the workings of the mind (the intangibles of conscious experience) and establish how they are linked to the anatomy and function of the brain (structure, chemistry, neural activity)." Tools like functional magnetic resonance imaging (fMRI) allow researchers to watch blood flow to specific regions of the brain, which serves as a proxy for the activity of those neurons.

One new method called diffusion MRI reveals major axon pathways by tracking the flow of water molecules through the brain. While the technique is still under development, researchers think it may have many useful clinical applications. This diffusion MRI image, from 2008, shows the brain of a patient who suffered a stroke in the thalamus and midbrain, resulting in broken and disrupted axon tracts (visible at bottom). Each line represents thousands of axons.