If gray matter is the workhorse of the brain, white matter is the coordinating director that allows for synchronized action. In other words, white matter is an often overlooked but essential system in our brains that facilitates communication and helps coordinate brain activity for smooth functioning.
If you don’t know much about white matter, you’re in good company. White matter has only recently become an area of scientific curiosity, with gray matter soaking up the majority of attention in previous years.
It used to be that we thought of white matter was just the messenger. A delivery system for the activity and decisions made by the rest of the brain. Truth be told, white matter does function as a communication system for impulses throughout the brain. But evolving research suggests white matter is involved in much, much more, from brain health as we age to psychological diseases.
How does the brain work?
The human brain is an incredibly powerful and delicate system. It has multiple regions that are responsible for various functions such as breathing, perception, decision-making, and self-awareness. It's safe to say that a lot goes on inside our heads.
In our dedication to understanding and promoting brain health, Muse conducted a brain health study in 2022. We asked study participants what they considered to be the most important aspect of brain health. Memory came up as a top priority, followed by focus and sleep.
While all aspects of brain health are crucial, it's important to understand the fundamental components of the brain – the gray and white matter.
First, it’s important to know how the brain communicates and conducts action.
All communication in the brain is conducted via neurons (nerve cells). Neurons are tiny but powerful cells that use electrical impulses and chemicals to send and receive information between brain regions and the central nervous system.
There are four important parts that make up neurons:
Dendrites: Serve as the arms of the cell body that receive signals from other neurons. These signals are sent through neurotransmitters. Once the neurotransmitters reach the dendrite, they trigger electrical changes that are then interpreted by the Soma.
Soma: The soma, also called the neuronal cell body, is where the genetic material for the cell is stored. Electrical and chemical signals processed through the dendrites are analyzed by the soma, which then passes on the signals to the axon.
Axons: Also known as nerve fibers, act like a freeway that transmits signals from the soma to the synapses and to nearby neurons.
- Myelin: An insulating material that, in healthy brains, covers the axon to prevent the nerve signals from degrading. The more myelin, the faster a signal can travel. Myelin also helps protect nerve fibers from injury.
Once the signal travels from the dendrites through the cell body and axon, they end up at the synapses. Here, they trigger the release of neurotransmitters through synaptic buttons which then spread the message to the next neuron.
What is gray matter?
If you were to look at a spliced image of the brain, you would see that the outer layer with its ridges and folds appears as a more gray color – this is the brain’s gray matter. It’s mostly made up of neuronal cell bodies, or soma.
Put simply, the gray matter does the heavy duty work of making sense of the world and our experiences. But the decisions and actions that result from that analysis are passed through and orchestrated by white matter.
What is white matter?
If we’re again looking at a scan of the brain, we see that beneath the outer gray matter layer of our brain, lives white matter.
White matter is mainly made up of densely packed bundles of nerve fibers, (axons and myelinated sheaths). These nervous fibers, also called white matter tracts, conduct a careful orchestration of sending and receiving signals.
These signals are what facilitate and coordinate movement, thought, and action through different parts of the brain, the brain stem, and the central nervous system.
Unlike gray matter which peaks in development by the time we reach about 11 or 12 years old, white matter continues developing through our 20s.
Myelin and white matter
Let’s talk about the role of myelin for a moment. Myelin is a white, fatty, waxy insulating material that covers most nerve cells. However, it does not cover the entire axon. Instead, it leaves gaps about every millimeter or so.
Some parts of the nerve cell, like the soma, are not coated in myelin. When comparing myelinated vs. unmyelinated axons, we see that myelinated axons pass information far faster than unmyelinated nerve cells.
For instance, electrical and sensory information processed in our brain’s gray matter must travel the full length of the nerve cell. With myelinated axons, the electrical information can hop from myelinated sheath to sheath, moving at faster rates.
In fact, researchers have found that myelinated axons transmit impulses up to 100 times faster than unmyelinated cells.
Myelin coverage increases as we age, finally encompassing our frontal lobes by our mid to late 20s.
White matter and psychological health
While research is still growing with the role white matter plays in our health, numerous studies confirm that white matter does, indeed, matter. Beyond simply transporting messages, white matter is essential for synchrony.
Consider for a moment that it can take hundreds of neuron signals working in coordination to do even the simplest tasks, such as raising your hand or smiling. Signals are being sent from all over the brain to prompt this action. For the action to be completed, the signals must work together. White matter and myelination helps moderate the speed of messaging so that signals can be coordinated into synchronized action.
When it comes to white matter health and strength of white matter tracts, research has found connections between white matter and IQ, as well as with reading ability. The greater the IQ or reading ability, the greater the fiber organization, the more efficient the signaling process.
White matter and diseases
White matter loss or deterioration has been linked with a number of diseases and mental disorders. First and foremost, white matter loss is linked with cognitive impairment. The less white matter we have, the slower and less coordinated our brain processes information.
Certain conditions like multiple sclerosis and Guillain-Barre syndrome attack myelin sheaths, leading to white matter degradation.
Other conditions that have been linked to white matter loss include:
- White matter disease (leukoaraiosis)
- Alzheimer’s disease
- Post-traumatic stress disorder
- Major depression
- Attention-deficit hyperactivity disorder
- Obsessive compulsive disorder
- Tourette’s syndrome
- Sleep deprivation
White matter disease
Also known as leukoaraiosis and white matter hyperintensities, white matter disease is a progressive, age-based disease that is said to pre-empt other health conditions. This means we are at higher risk for it as we age, and it worsens over time. When someone has white matter disease, the myelin protecting their nerve fibers breaks down.
Symptoms of white matter disease often include:
- Loss of balance
- Falling down more frequently
- Walking at a slower pace
- Finding it difficult to do two things at once, like walking and talking
- Mood shifts
- Depressive symptoms
Researchers have linked numerous factors to white matter disease, including but not limited to: smoking cigarettes, high cholesterol, high blood pressure, and heart disease.
White matter loss can lead to serious issues, but thanks to modern EEG technology like the Muse headbands, conditions can be detected early on. Our user-friendly meditation wearables, trusted by neuroscientists and researchers, boast an 86% accuracy in detecting mild cognitive impairment.
How can you keep white matter healthy?
Meditation is also a great activity to keep white matter healthy. One study compared the brain scans of 33 meditators and 31 non-meditators. Unsurprisingly, they found higher levels of white matter preservation and lower levels of white matter loss compared to non-meditators and accounting for age.
If you’re looking to start or improve your meditation, the Muse 2 Headband is a great tool to deepen your practice by helping you understand your brain’s function with real-time biofeedback. Meditation with biofeedback not only enhances cognitive performance but also reduces stress and increases relaxation, offering a holistic approach to wellbeing.
Good sleep is also beneficial to a healthy white matter. If you’re having trouble sleeping, the Muse S Headband is a meditation and sleep wearable that can help. Personalized sleep tracking provided by Muse S allows a deeper understanding of sleep patterns, helping you achieve a more restful sleep. With its impressive record of enhancing sleep quality by 20%, our EEG sleep technology contributes to the preservation of healthy white matter and the overall vitality of the brain.