Human head and brain. Coloured magnetic resonance imaging (MRI) scan of a midsagittal section through the head of a healthy 37-year-old female patient, showing structures of the brain, intra-cerebral arteries, spine, and facial tissues. The highly folded area of the brain is the cerebrum (upper centre), which is responsible for conscious thought, emotion and voluntary movement. The arch-like structure beneath it is the corpus callosum, which facilitates communication between the left and right cerebral hemispheres. At bottom right is the cerebellum, which controls muscle coordination and balance. This is an MRI scan under gadolinium injection.