False-colour magnetic resonance image (MRI) of a coronal (frontal) section through the head of a healthy human infant, showing the division of the brain into left and right cerebral hemispheres. MRI distinguishes between the outer grey and inner white matter tissue components that make up the brain. In this image, the outer grey matter appears red, and the inner white matter yellow. MRI is also called NMR - nuclear magnetic resonance - the name of the physical phenomenon on which the imaging technique is based.