A simple starting point
Introduction
The brain and spinal cord contain several kinds of tissue. Two important categories are grey matter and white matter. They work together, but they are not made of exactly the same structures or arranged in the same way.
In broad terms, grey matter contains many neuron cell bodies and areas that process information. White matter contains bundles of axons, many wrapped in a fatty insulating material called myelin, which helps signals travel between regions.
Grey matter is closely associated with processing and interpreting information. White matter forms communication routes between processing areas. Neither works alone.
Grey matter
Grey matter contains neuron cell bodies, dendrites, connections between neurons, supporting glial cells, and small blood vessels. The name describes its appearance in preserved nervous tissue; living tissue can have pinkish or brownish tones as well.
Where is grey matter found?
In the cerebrum, grey matter forms much of the outer cerebral cortex. It is also found in deeper groups of cells called nuclei. The cerebellum has an outer grey-matter cortex and deeper nuclei. In the spinal cord, grey matter lies more centrally and forms a recognisable H-shaped or butterfly-shaped region surrounded by white matter.
What does grey matter do?
Grey matter includes many sites where nervous-system information is received, combined, and interpreted. Depending on the region, it supports movement, sensation, language, memory, attention, learning, planning, and the control of automatic body functions.
White matter
White matter is made largely from axons, the long projections that carry electrical signals away from neuron cell bodies. Many axons are surrounded by myelin. This lipid-rich sheath gives white matter its paler appearance and helps signals move efficiently.
How is white matter organised?
Axons are grouped into pathways and tracts. Some connect nearby areas, while others link distant parts of the brain or carry information between the brain and spinal cord. Oligodendrocytes make myelin in the central nervous system, while astrocytes and other support cells help maintain the surrounding environment.
What does white matter do?
White matter provides communication routes. Ascending pathways carry some sensory information towards the brain, while descending pathways carry motor instructions towards the spinal cord and body. Connections within the brain also allow separate regions to coordinate their work.
Grey matter
Rich in neuron cell bodies and local connections.
Often involved in processing, interpretation, and control.
Found in the cerebral and cerebellar cortices, deeper nuclei, and the centre of the spinal cord.
White matter
Rich in myelinated axons and supporting cells.
Often involved in communication between processing areas.
Found deep within much of the brain and around the spinal cord’s central grey matter.
Health and disease
Changes affecting grey or white matter can have many causes, including ageing, inflammation, injury, disrupted blood supply, and neurodegenerative disease. The effects depend on which pathways or processing regions are involved.
Conditions affecting grey matter may influence memory, movement, sensation, or decision-making. Conditions affecting white matter may interfere with communication between regions and can contribute to changes in coordination, strength, sensation, or thinking. A scan finding alone does not explain a person’s health; interpretation belongs with a qualified clinician who knows the wider context.
Why the distinction matters
Grey matter and white matter are best understood as partners. Processing areas need communication pathways, and communication pathways need processing areas. Learning the difference is useful, but it is just one step towards understanding the whole nervous system.
Summary
Grey matter contains many neuron cell bodies and is found in the cerebral and cerebellar cortices, deeper nuclei, and the central part of the spinal cord. White matter contains axon bundles, often insulated by myelin, and forms pathways within the brain and between the brain and spinal cord.
Together, these tissues allow the nervous system to receive information, interpret it, coordinate responses, and communicate across the body. This page is an educational overview, not a diagnosis or a substitute for medical advice.