Injury to Brain MatterWhite vs. Grayness Affair Injury

Brain damage is often described as either a white or grey affair injury, but what is the departure?

White Affair Injuries

White affair injuries occur when white matter tracts (bundles of myelinated axons) are damaged. Damage essentially cuts off or limits communication between areas of grey matter (neuron cell bodies and dendrites, the neuropil, glial cells, and capillaries).

Perhaps the easiest example to envision is a spinal cord injury.

The exterior of the spinal cord is composed of large white matter tracts. Transecting or compressing these tracts tin can lead to paralysis because the information from the encephalon's motor cortex (grey affair) can no longer reach the spinal string and muscles. White matter tracts relaying sensory information from the muscles and skin to the brain can also be lost. In this case, the patient may not be able to feel an ice cube placed on his or her skin.

White affair injuries are very serious, merely, depending on the type and extent of the injury, extensive recovery may occur. Equally long as the neuron cell bodies remain healthy, axons can regrow and slowly repair themselves. Functional recovery may as well occur if the information can be transmitted through an culling road. In many cases, this occurs through the strengthening of weak connections that already exist.

Greyness Affair Injuries

Neuronal death is at the heart of grey matter brain damage.

The neuron jail cell bodies are responsible for keeping the entire neuron alive and healthy and that takes a lot of energy. Grey affair is therefore very susceptible to injury when oxygen levels are low (hypoxia) such as during an ischemic consequence.

Impairment also occurs when the local environment changes such equally during an intracerebral hemorrhage or when physical impairment occurs. Damaged neurons and glia likewise release factors that tin increase the effect of the injury. In many cases, the initial damage causes a series of downstream effects that can initiate apoptosis (programmed cell decease).

Once the damage has occurred, the cell cannot support its axons or dendrites and the entire cell dies. This is especially true in neurons that have big cell bodies and long axons. In dissimilarity, afterwards a white matter injury, a healthy prison cell trunk may be able to repair the damaged axon.

Similar white thing injuries, the type and extent of the injury largely dictate recovery.

Young infants and children often have meliorate outcomes than adults since their neural systems are withal developing and more adaptable. Targeted rehabilitation training tin can also improve functional outcomes. For instance, after selective damage to the motor cortex, fine finger movements can be improved when the rehabilitative preparation results in an expansion of the finger motor representation inside the motor cortex. In other words, nearby neurons tin can begin to take over the functions of the damaged neurons.

White and Grey Matter Interactions

Although white and grey matter injuries are often presented as separate entities, information technology is hard to have 1 without the other.

This is because (1) many injuries simply involve both gray and white matter areas, (ii) a single neuron can accept its cell trunk and dendrites in the grey matter and an axon in the white thing, and (3) because neurons depend on their interactions with other neurons.

White matter harm tin cause a great deal of stress and increase the energy demands on the neuron. In some cases, the neuron will not be able to meet the energy demands and the entire neuron will die (cell body, axon, and dendrites). This oft starts with the retraction of the injured axon.

On the other stop, the grey thing targeted past that axon (i.due east. the postal service-synaptic neurons) tin shrink and die from inactivity or be taken over by other functions (i.e. innervated past other neurons). Grey matter almost the site of white affair injury tin likewise be damaged by factors released from damaged axons and vice versa.