Plasticity and functional recovery

Question 1

define plasticity

Answer 1

plasticity, also known as neuroplasticity or cortical remapping, describes the brains tendency to change and adapt (functionally and physically) as a result of experience and new learning.

Question 2

Describe the brain in childhood and infancy

Answer 2

During infancy, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 by the age of 2-3 years old. This equates to twice as many as there are in the adult brain.

Question 3

Describe cognitive pruning

Answer 3

As we age, rarely used connections are deleted and frequently used connections are strengthened in a process known as cognitive pruning

This shows that the brain is in a continual state of change from growth in early years to change and refinement in adulthood as we learn and experience.

Question 4

Explain how plasticity can be negative using examples

Answer 4

Examples of this would include prolonged (illegal) drug use leading to poorer cognitive function and old age being associated with dementia. Both are due to changes in the brain.

Question 5

List 2 studies for plasticity

Answer 5

• Macguire et al 2000
• Tibetan monks

Question 6

Outline Macguire et al 2000

Answer 6

Macguire et al studied the brains of London taxi drivers using an MRI and found significantly more grey matter in the posterior hippocampus than in the matched control group. This part of the brain is associated with the development of spatial and navigational skills in humans and other animals.

As part of their training London Cabbies must take a complex test called ‘the knowledge’, which assesses their recall of the city streets and possible routes.

Question 7

What were the findings of Macguire et al 2000

Answer 7

the longer they had been doing the job the more pronounced was the structural difference (a positive correlation).

Question 8

What are the strengths of Macguire et al 2000

Answer 8

S – matched control group – can say with more certainty that it is due to their driving rather than extraneous variables.
S – scientific – objective measurements - MRI – more accurate

Question 9

what are weaknesses of Macguire et al 2000

Answer 9

W – sample – only from London, only taxi drivers – cant generalise to other jobs
W – they were not tested before they underwent the training

Question 10

Outline the Tibetan monks study

Answer 10

• 8 practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience.
• Both groups were fitted with electrical sensors and asked to meditate for short periods.

Question 11

What were the findings of the Tibetian monks study

Answer 11

The electrodes picked up on much greater activity of gamma waves (important because they coordinate neuron activity) in the monks. While the students showed only a slight increase in gamma wave activity while meditating.

Question 12

Give a conclusion for the Tibetian monks study

Answer 12

The researchers concluded that meditation not only changes the workings of the brain in the short term, but may also produce permanent changes, based on the facts that the monks had far more gamma wave activity than the control group even before they started meditating.

Question 13

evaluate the Tibetian monks study

Answer 13

S - used electrodes - scientific - increase accuracy
W - small sample size with inexperience from the students - may have struggled - squewed the sample

Question 14

What is the connection between plasticity and age

Answer 14

There is also a natural decline in cognitive functioning with age that can be attributed to changes in the brain.
This has led researchers to look for ways in which new connections can be made to reverse this effect.

Question 15

Give a piece of research into plasticity and age.

Answer 15

Boyke et al (2008) found evidence of brain plasticity in 60 yr. olds taught a new skill – juggling. They found increases in grey matter in the visual cortex, although when practicing stopped, these changes reversed.

Question 16

define functional recovery

Answer 16

Functional recovery is a form of plasticity. Following trauma (such as infection or physical injury) unaffected areas of the brain are sometimes able to adapt or compensate for those areas that are damaged. The functional recovery that occurs in these cases is an example of neural plasticity

Question 17

define spontaneous recovery

Answer 17

is the term used to refer to functional recovery that happens very quickly after a trauma.

Question 18

Explain what happens to the brain during recovery

Answer 18

the brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage. Secondary neural pathways that would not typically be used to carry out certain functions are ‘unmasked’ to enable functioning to continue. This process is supported by a number of structural changes.

Question 19

List the structural changes that happen during functional recovery

Answer 19

• Axon sprouting
• reformation
• recruitment of homologous areas

Question 20

define/ explain axon sprouting

Answer 20

new nerve endings grow and connect with undamaged areas.

Question 21

define/ explain reformation in functional recovery

Answer 21

the reforming of blood vessels

Question 22

define/ explain recruitment of homologous areas for functional recovery

Answer 22

the brain recruits similar areas on the opposite hemisphere to do specific tasks

e.g. if Broca’s area was damaged then an area on the right might take over

Question 23

Give example(s) research into functional recovery

Answer 23

• Tajiri et al 2013
• Schneider et al 2014

Question 24

outline Tajiri et al 2013

Answer 24

Tajiri et al (2013) provided evidence for the role of stem cells in recovery from brain injury. They randomly assigned rats with traumatic brain injury to one of 2 groups. One group received transplants of stem cells into the region of the brain affected by traumatic injury. The control group received a solution infused into the brain containing no stem cells.

Question 25

What were the findings of Tajiri et al 2013

Answer 25

Three months after the brain injury, the brains of stem cell rats showed clear development of neuron-like cells in the area of injury. This was accompanied by a solid stream of stem cells migrating to the brain’s site of injury. This was not the case with the control group.

Question 26

Evaluate Tajiri et al 2013

1S, 1W

Answer 26

W – animal studies are hard to generalise to humans
S - Animal studies enable us to monitor the function of the brain before and after trauma because we cause it. Ethically we couldn’t do this in humans and it’s unlikely that we would have measured their function before a natural event (because we didn’t know it was going to happen).

Question 27

Outline Schneider et al 2014

Answer 27

Schneider et al (2014) found that patients with the equivalent of a college education are seven times more likely than those who didn’t finish high school to be disability-free one year after a moderate to severe traumatic brain injury. They carried out a retrospective study based on data from the US Traumatic Brain Injury Systems Database.

Question 28

Describe the findings of Schneider et al 2014

Answer 28

Of the 769 patients studied (large sample), 214 had achieved disability-free recovery (DFR) after one year. Of these, 39.2% of the patients with 16 or more years of education had achieved DFR, as had 30.8% of those with 12-15 years of education, and just 9.7% of those with less than 12 years of education achieved DFR after just one year.

DFR - disability free recovery

Question 29

Give a conclusion for Schneider et al 2014

Answer 29

The researchers concluded that ‘cognitive reserve’ (associated with greater educational attainment) could be a factor in neural adaptation during recovery from traumatic brain injury.

Question 30

Give a strength of Schneider et al 2014

Answer 30

S - large sample size

Question 31

Fully outline Lashley 1950

including results

Answer 31

experiment on rats where he removed 10-50% of their cortex to see if it effected the rat’s ability to learn a route through a maze. In his experiment he found that no area was proven to be more important than any other when it came to learning the route, in fact the process of learning seemed to use every part of the cortex rather than a specific area. This suggests that higher cognitive processes (e.g. learning) are not localised in the brain of rats but distributed in a holistic way.

Question 32

Evaluate Lashley

Answer 32

A weakness of Lashley 1950 though is that he used rats, this is a weakness because he is trying to apply to humans, and it is hard generalise from rats to humans. This means that Lashley’s 1950 experiment can only be applied to rats and suggested for humans.