Functional Recovery

Question 1

Describe early cases of functional recovery

Answer 1

• In the 1960s, researchers studied cases where stroke victims regained functioning
• They found that when brain cells are destroyed/damaged during a stroke, the brain re-wires itself over time so that some function can be regained

Question 2

How does functional recovery wok?

Answer 2

• Although parts of the brain may be damaged or destroyed due to trauma, other parts can take over the functions that were lost.
• Neurons next to damaged areas can form new circuits that resume some of the lost function

Question 3

What are the two mechanisms for recovery?

Answer 3

• Neuronal unmasking
• Stem cells

Question 4

Describe neuronal unmasking as a mechanisms for recovery

Answer 4

• Wall identified ‘dormant synapses’ in the brain. These are synaptic connections that exist anatomically but their function is blocked.
• Under normal conditions these synapses may be ineffective as the rate of neural input to them is too low for them to be activated
• But, increasing the rate of input of these synapses, as would happen when a surrounding brain area is damaged, can then ‘unmask’ these dormant synapses.
• The unmasking opens connections to brain regions that aren’t normally activated, and in time gives way to the development of new structures.

Question 5

What are stem cells?

Answer 5

Stem cells are unspecialised cells that can give rise to different cell types that carry out various functions, including the function of nerve cells

Question 6

What are the 3 views on how stem cells can provide treatment to brain damaged caused by injury or neurodegenerative disorders?

Answer 6

• Stem cells implanted in the brain would replace dead/dying cells
• Transplanted stem cells secrete growth factors that somehow ‘rescue’ the injured cells
• Transplanted cells form a neural network, which links an uninjured brain site, where new stem cells are made, with the damaged region of the brain

Question 7

Give evaluation for functional recovery (animal studies)

Answer 7

• Tajril et al provided evidence for the role of stem cells in recovery after brain injury
• They randomly assigned rats with brain injury to a group. One group received stem cell transplants to the affected region. The control group received a solution into the brain with no stem cells. 3 months later, the brains of the stem cell rats showed development of neuron-like cells in the injured area, accompanied by a solid stream of stem cells migrating to the brain’s site of injury.
• New neuronal cells wasn’t evident in the control group, supporting the role played by stem cells in recovery.

Question 8

Give evaluation for functional recovery (age differences)

Answer 8

• It’s commonly accepted that functional plasticity reduces with age (Huttenlocher)
• According to this, the only option after brain injury beyond childhood is to develop compensatory behavioral strategies to deal with cognitive deficits. However, studies have suggested that abilities thought to be fixed in childhood can be modified in adults with intense retraining
• Despite this, Elbert et al conclude the capacity for neural reorganisation is greater in children than in adults, as shown by the extended practice that adults require for change.

Question 9

Give evaluation for functional recovery (educational attainment)

Answer 9

• Schneider et al found patients with a college education were 7 times more likely, than those who didn’t finish high school, to be disability-free a year after a moderate to severe brain injury
• They did a retrospective study based on data from the US Traumatic Brain Injury Systems Database. Of 769 patients, 214 achieved disability-free recovery (DFR) after a year. Of these, 39% had 16 or more years of education, 30% had 12-15 years of education, and 9% had less than 12 years of education.
• Researchers concluded that ‘cognitive reserve’ (associated with greater educational attainment) was an important factor in neural adaptation during recovery from traumatic brain injury