What Is Grey Matter Made Of? Key Components and Placement Explained
Our brain is deemed as one of the most complex and intriguing structures. But anatomically it can be divided into a few discrete parts which are: the right and left hemispheres, frontal lobes, occipital, temporal, and parietal lobe. Another common divider for the brain is grey matter and white matter.
Grey and white matter tissues are present in our central nervous system. Grey matter forms the outermost layer of our brain and has a pinkish-grey tone (that’s where the name comes from). The grey matter has an essential role in enabling human beings to function normally on a daily basis. Grey matter and white matters are both vital sections of the brain and spinal cord.
We will learn a great deal about the grey matter in the brain in this article. We will be covering functions of grey matter, the difference between grey and white matter, and also learning how to increase grey matter through certain activities.
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Grey Matter Contents
The material between our ears is present in two shades; white and grey. The difference between these two matters is in the amount of fat content. The grey matter contains:
High concentration of neuronal cell bodies (which is responsible for its grey tone).
Unmyelinated Axons - Axons are elongated portions of the neuron which is placed at the center of the cell in between axon and soma. These axons are unmyelinated which means they do not have a covering of fatty protein which is whitish in color.
Non-neuron Brain Cells Which are also Called Glial Cells - These cells provide energy and nutrients to the neurons. They also help in transporting glucose to the brain, clean excess chemicals out of the brain, and may also affect the intensity of how neurons communicate.
Grey matter forms from ectoderm (the outermost layer of skin) in early development years and continues to form till we attain 8 years of age. After this point, the grey matter starts decreasing in brain areas but the matter density increases. This higher density allows further mental development and higher processing powers of our brains.
Grey Matter in Brain
Grey matter in the brain is found in abundance in the cerebellum, brain stem, cerebrum, and spinal cord.
The cerebrum has a sheet of grey matter of thickness of 2 to 5 mm.
Grey matter in the brain is highly concentrated in the Cerebellum, which is just 10% of the total brain volume. The cerebellum contains more neural cell bodies than all the other parts of the brain combined.
Grey Matter Composition and Placement
The grey matter has somas which are neuronal cell bodies. These structures are circular in shape and contain the nucleus of the cells. Our cerebellum has 10 to over 50 billion cells.
White matter is a layer of nerve fibers lying below the grey matter surface. White matter connects neurons in the grey matter to other parts of the brain.
Grey matter is present throughout the inside of the spinal cord in a horn-like structure and white matter fills up the surrounding sections of the spinal cord.
Grey matter around the cerebrum is referred to as the cortex of the brain. We have two major cortexes in our brains: cerebellar and cerebral cortexes.
The cortex has a wrinkled appearance due to the presence of ridges (called gyri) and grooves (called sulci).
Gyri and sulci increase the surface area of the brain which allows more neurons to be present (which is not possible on a smooth surface). This is crucial for the effective working of the brain.
Grey matter also contains glial cells which are supportive to the neurons. Glial cells, specifically oligodendrocytes (they produce myelin) and astrocytes are present in numbers that are 10 times more than neurons.
Grey matter also has capillary blood vessels and neuropil which is a mix of glia, dendrites, and unmyelinated axons.
Grey Matter Function
Grey matter performs many functions in our bodies that are basic for living. It enables us to control our movements, regulate emotions, retain memories, and controls many other aspects of human life that depend on grey matter in brain.
Grey matter processes information in the brain. Grey matter receives signals from our sensory organs or other areas within the grey matter. There are structures in grey matter that process these signals. These sensory stimuli are then directed to the neurons present in our central nervous system where synapses produce a response to the stimuli.
Grey matter in the cerebellum affects human personalities and plays a role in:
Motor functioning and automatic movements
Intelligence
Organization
Planning
Processing sensory information
Language processing
The grey matter of the spinal cord has its own functions. The anterior column of grey matter connects to the brain via a pathway known as the pyramidal tract (originating in the cerebral cortex) and is essential for motor movements
The posterior grey matter in the spinal cord helps in receiving sensory signals and enables our body’s constant interaction with the environment.
The lateral grey matter in the spinal cord is present in the middle and regulates the autonomic nervous system by activating the sympathetic nervous system. Our bodies’ response to stressful situations is stimulated by the sympathetic nervous system. For example, when our heartbeat accelerates, the nervous system sends extra blood to muscles.
How to Increase Grey Matter
There are a few ways of boosting your mood and reducing stress which also leads to an increase in the grey matter in the brain.
Meditation - As per a study from Harvard University, long-term meditation has been shown to increase the amount of grey matter in the brain within the sensory and insula region and sensory and auditory cortex. Meditation alters brain wave patterns and helps you sleep better.
Physical Activities - Apart from the health benefits of physical activities, science has proven that working out increases grey matter in the brain. Cardiovascular exercises enhance the central nervous system and increase both grey matter and white matter in our brains.
Playing Video Games - Many people feel that playing video games is bad for your brain. But according to a study done by the Macquarie University of Sydney and the University of Electronic Science and Technology of China, video games change the brain structure. They heighten the connection between a few insular cortex subregions and result in a larger surface area and greater volume of grey matter
FAQs on Grey Matter: Definition, Role & Significance
1. What is grey matter and where is it found in the central nervous system?
Grey matter is a major component of the central nervous system, consisting mainly of neuronal cell bodies (soma), dendrites, glial cells, and unmyelinated axons. It is the primary site of neural processing. In the brain, it forms the outer layer of the cerebrum (the cerebral cortex) and is also found in deep structures like the thalamus and basal ganglia. In the spinal cord, it forms a butterfly-shaped core in the centre.
2. What are the main differences between grey matter and white matter?
The main differences between grey and white matter are based on their composition and function.
- Composition: Grey matter is rich in neuronal cell bodies, dendrites, and glial cells. White matter is primarily composed of long-range myelinated axons, which are covered in a fatty myelin sheath that gives it its whitish colour.
- Function: Grey matter is where information is processed and integrated. It is involved in functions like memory, emotions, and muscle control. White matter acts as the communication network, transmitting nerve signals between different brain regions and between the brain and the spinal cord.
- Location: In the brain, grey matter is mostly on the surface (cortex), while white matter is in the interior. In the spinal cord, this is reversed, with grey matter at the core and white matter surrounding it.
3. What is the primary role or significance of grey matter in the brain?
The primary significance of grey matter is its role as the brain's main processing centre. Because it contains a high concentration of neuronal cell bodies, it is where all synaptic activity, or "thinking," occurs. Its key functions include controlling movement, memory, emotions, and sensory perception (like seeing, hearing, and touch). Essentially, all higher-order cognitive functions depend on the health and activity of the grey matter.
4. How is grey matter arranged in the spinal cord, and how does it differ from its arrangement in the brain?
The arrangement of grey matter differs significantly between the spinal cord and the brain. In the spinal cord, grey matter forms a central, H-shaped or butterfly-shaped core. This core is divided into regions called horns (dorsal, ventral, and lateral) that handle specific sensory and motor information. Conversely, in the brain, grey matter primarily forms the outermost layer, known as the cerebral cortex, and is also found in clusters called nuclei deep within the brain. This structural difference reflects their roles: the spinal cord's central grey matter acts as a relay and reflex station, while the brain's vast cortical grey matter handles complex processing.
5. What happens to our cognitive functions if grey matter is damaged or lost?
Damage or loss of grey matter can have severe consequences for cognitive and motor functions, as this is where information processing occurs. Depending on the affected area, symptoms can include:
- Memory loss and difficulties forming new memories.
- Cognitive impairment, affecting language, attention, reasoning, and judgment.
- Motor control issues, such as problems with muscle movement, coordination, and fine motor skills.
- Sensory deficits, including problems with vision, hearing, or touch.
6. Can a person increase their brain's grey matter? If so, how?
Yes, research suggests that the volume of grey matter is not fixed and can be influenced by lifestyle and activities. This ability of the brain to change is called neuroplasticity. Activities that may help increase or preserve grey matter density include:
- Learning new skills: Engaging in mentally challenging activities like learning a musical instrument or a new language.
- Physical exercise: Regular aerobic exercise has been shown to increase grey matter volume in regions associated with memory.
- Meditation and mindfulness: These practices can lead to increased grey matter density in areas related to attention and emotional regulation.
7. Why is grey matter crucial for processing sensory information like touch and pain?
Grey matter is crucial for processing sensory information because it contains the neuronal cell bodies that receive and interpret incoming signals. When you touch something, sensory neurons send signals up the spinal cord to specific regions of the grey matter in the brain, particularly the somatosensory cortex. Here, the signals are decoded to identify the location, pressure, temperature, and texture. Similarly, pain signals are processed in grey matter areas that not only identify the location and intensity of the pain but also generate an emotional response to it. Without grey matter, these signals would be transmitted but not understood.
8. Does the amount of grey matter change as a person ages?
Yes, the amount and density of grey matter naturally change throughout a person's life. Grey matter volume generally increases during childhood and adolescence, peaking in the late teens or early twenties. After this peak, there is a gradual, natural decline in grey matter volume as part of the normal ageing process. This decline can affect cognitive functions like memory and processing speed. However, engaging in mentally and physically stimulating activities can help mitigate this age-related loss.
