5.2 Plasticity After Brain Damage Flashcards
The possible cause of brain damage include ____, ____, exposure to ____ or ____ substances, and degenerative conditions such Parkinson’s disease and Alzheimer’s disease.
tumours, infections, exposure to radiation or toxic
Almost all survivors of brain damage show ____ recovery to some degree.
behavioural
In young people, the most common cause in ____ ____ ____, a sharp blow to the head resulting from an accident or assault that does not puncture the brain.
closed head injury
____ head injuries, common in certain sports, are more worrisome. After a severe head injury, recovery is slow and often incomplete.
Repeated
One cause of damage after closed head injury is the ____ ____ that drive brain tissue against the inside the skull. Another cause is blood clots that interrupted bloodflow to the brain.
rotational forces
A common cause of brain damage, especially older people, is temporary interruption of normal blood flow to a brain area during a ____, also known as a ____ accident.
stroke : cerebrovascular
The more common type of stroke is ____, the result of a blood clot or other obstruction in an artery.
ischemia
The least common type of stroke is ____, the result of a ruptured artery.
hemorrhage
And ischemia, the neurons deprived of blood lose much of their ____ and ____ supplies.
oxygen and glucose
In haemorrhage, the neurons are flooded with blood and excess ____, ____ and other chemicals.
oxygen, calcium
Both ischemia and haemorrhage lead to many of the same problems, including ____ (the accumulation of fluid), which increases pressure on the brain and the probability of additional strokes.
edema
Both ischemia and haemorrhage also impair the ____ pump, leading to an accumulation of sodium inside neurons.
sodium-potassium
Today, prospects are good for ischemia if physicians act quickly. A new drug called ____ ____ ____ (tPA) breaks up blood clots. To get significant benefit, a patient should receive tPA within three hours after stroke, although slight benefits are possible during the next several hours.
tissue plasminogen activator
TPA can make matters worse in a haemorrhage. The usual decision is to give the tPA. Haemorrhage is less common and usually ___ anyway, so the risk of making a haemorrhage worst is small compared to the hope of alleviating ischemia.
fatal
The most effective known method of preventing brain damage after strokes in laboratory animals is to ____ the brain.
cool
Another procedure might surprise you: exposure to ____ (chemicals found in marijuana) minimise the damage caused by strokes in laboratory animals.
cannabinoids
Research on laboratory animals indicates that cannabinoids are most effective if taken shortly ____ the stroke. It would be difficult to apply that advice in humans.
before
After the first days following brain damage, many of the surviving brain areas ____ or ____ their activity. In some cases, one area more or less takes over the function of another, damaged area.
increase or reorganise
In other cases, surviving brain areas do not take over the functions of the damaged area, but they ____ in various ways.
compensate
A behavioural deficit after brain damage reflects more than just the cells that died. After damage to any brain area, other areas that have lost part of their normal input become less ____.
active
____ refers to the decreased activity of surviving neurons after damage to other neurons.
Diaschisis
If diaschisis contributes to behavioural deficits following brain damage, then increased ____ should help.
stimulation
____ drugs also promote recovery in brain damage.
Stimulant
With impaired movement or depth perception in laboratory animals, injecting ____ significantly enhanced both behaviours, and animals that practised behaviours under the influence of amphetamines showed long-lasting benefits.
amphetamines
With impaired movement or depth perception in laboratory animals, injecting a different drug to block dopamine synapses ____ behavioural recovery.
impaired
Although amphetamine is too risky for use with human patients, other stimulant drugs are more promising. A related idea is to use drugs that block the release of ____, the brains main inhibitory neurotransmitter.
GABA
Although a destroyed cell body cannot be replaced, damaged axons do ____ ____ under certain circumstances.
grow back
