Gray matter is an important component of the central nervous system and significantly determines its functions. The brain‘s intelligence performance is particularly associated with the gray matter. However, in addition to intelligence, it controls all perceptual processes and motor performance in humans.
What is gray matter?
The central nervous system is composed of both gray matter and white matter. Unlike white matter, gray matter is composed of the actual cell bodies of nerve cells (neurons) and glial cells. White matter, on the other hand, is composed of the nerve fibers surrounded by membranes, the axons. Between the neurons and glia cells, there are still the neurophilia and the capillaries. The actual processing of the central nervous system takes place in the neurons. The glial cells assume a supporting function. However, they are not involved in the transmission processes of the nervous system. The neurophilem as a so-called nerve felt provides the link between the individual cells. Finally, the capillaries are responsible for supplying the cells with oxygen and nutrients. The name gray matter results from the gray coloration of the preparations of these areas preserved in formalin. However, the gray matter in living organisms does not appear gray, but pink. Gray matter is present in all parts of the central nervous system. This is equally true of the brain, spinal cord, and neural pathways. However, the two components, gray and white matter, are arranged differently in different parts of the nervous system.
Anatomy and structure
There are three different arrangement possibilities for the gray matter. It should always be noted that it always occurs together with the white matter. The white matter represents an area that mainly contains the nerve fibers of the neurons. The actual cell bodies gather in the gray matter area. In the brain, the gray matter is located at the periphery. Thus, the so-called cortex, the cerebral cortex, is composed of gray matter, while inside the cerebrum the white matter is located as the cerebral medulla. Both the cerebrum and the cerebellum are surrounded by a cortex of gray matter. In various other areas of the brain, there are nuclei of gray matter surrounded by white matter. This is especially true of the diencephalon and brainstem. In the spinal cord, the gray matter is on the inside. There, the white matter is on the outside. It has been found that the amount of gray matter in the brain correlates with intelligence performance and all other brain performance. However, due to lack of space, the brain cannot expand indefinitely. The biological solution consists in an increasingly complicated folding of the cerebral cortex. In the process, its surface area is increased, with more space for the gray matter. The human cortex contains between 19 and 23 billion nerve cells, the interconnection of which determines large parts of its brain performance.
Function and tasks
The gray matter controls all brain functions as well as all central nervous system functions. The cortex of the cerebrum is responsible for several basic functions. It consists of four lobes called the frontal, parietal, temporal, and occipital lobes. The frontal lobe controls motor processes, motivation, drive, and mental performance. The other three lobes mainly process signals from sensory organs. For example, the parietal lobe is responsible for touch stimuli. The temporal lobe processes all auditory stimuli and the occipital lobe all visual stimuli. The cortex of the cerebellum controls balance and coordination. The brainstem processes basic control mechanisms. The diencephalon relays signals to the cerebrum. It consists of gray matter nuclei that function as the thalamus, hypothalamus, epithalamus and subthalamus. The thalamus plays a special role in signal transmission to the cerebrum. In the spinal cord, the gray matter is responsible for the motor function of the skeletal muscles and for the sensitivity of the nerve cells. In the form of nerve cords, the fiber bundles of nerve cells are guided through the spinal canal. Inside these nerve bundles is the gray matter. The fiber bundles split in an h-shape into an anterior and posterior column.Because of its function, the anterior column is called the motor anterior root and the posterior column is called the sensory posterior root.
Diseases
When certain parts of the central nervous system fail, characteristic signs of failure result. In the cerebral cortex, many areas lie side by side, performing quite different functions. In case of local injuries or disease-related failures, partial disturbances of perceptual processes may occur. For example, if the visual center is destroyed, blindness occurs even though the eyes are fine. The visual stimuli are transmitted from the eye to the brain, but in this case a processing of the optical impressions is no longer possible. If higher cortical fields fail, the patient can see but cannot recognize the movements, colors or faces. If the broca center is damaged, the ability to speak is severely impaired. However, speech comprehension does not suffer. If the frontal lobe is damaged, there may be a decrease in intelligence and a change in personality. Damage to specific areas of the brain can result from injury, stroke, or other disease processes. Damage to the spinal cord, in turn, is often the cause of paralysis and paraplegia, as its nerve cords are responsible for the motor function of skeletal muscles. Such damage is caused by injury or pinching of nerves as part of a herniated disc. Nerve entrapment can cause temporary paralysis, which usually disappears once the cause is removed. In severe cases, however, paraplegia can develop here as well due to the death of nerve fibers.
