White matter fibres. Coloured 3D diffusion tensor imaging (DTI) scan of the bundles of white matter nerve fibres in the cerebellum. The fibres transmit nerve signals between brain regions and between the brain and the spinal cord. The cerebellum controls sensory perception, motor control and coordination. DTI scans show the diffusion of water along white matter fibres, allowing their orientations and the connections between brain regions to be mapped.