plasticity and functional recovery

Question 1

what is plasticity

Answer 1

brains ability to physically and functionally adapt and change in response to trauma (to the brain), new experiences and learning

Question 2

brain plasticity

Answer 2

by 2-3y we have around 15,000 synapses per neuron (Gopnik et al)
- synaptic pruning takes place
- recent research shows that at any time in life, existing neural connections can change and new ones can be formed

Question 3

what is synaptic pruning

Answer 3

a process where rarely used connections are deleted and frequently used ones are strengthened

Question 4

research into plasticity

Answer 4

1. Maguire et al
2. Draganski et al

Question 5

Maguire et al

Answer 5

studied brains of London taxi drivers
- found significantly more grey matter in posterior hippocampus than in a control
- part of the brain associated w development of spatial and navigational skill
- London cab drivers must have good recall of the city streets and possible routes
- the longer they were in the job, the more pronounced the structural difference

Question 6

Draganski et al

Answer 6

imaged the brains of medical students
- 3 months before and after exams
- learning induced changes were seen in the posterior hippocampus and parietal cortex

Question 7

what is functional recovery

Answer 7

brains ability to transfer functions from areas damaged by trauma to healthy parts of the brain
- maintains normal functioning

Question 8

how does this process happen

Answer 8

healthy brain areas take over the functions of the damaged/ missing areas
- suggested that this process can occur quickly after trauma and then slow down after several weeks or months

Question 9

what happens in the brain during recovery

Answer 9

• brain is able to rewire and reorganise itself by forming new synaptic connections close to damaged area
• secondary neural pathways are activated to enable functioning to continue

Question 10

structural changes that support functional recovery

Answer 10

• axonal sprouting
• reformation of blood vessels
• recruitment of homologous areas

Question 11

what is axonal sprouting

Answer 11

the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways

Question 12

reformation of blood vessels

Answer 12

supports recovery by increasing blood flow to activate areas

Question 13

recruitment of homologous areas

Answer 13

recruit similar areas on the opposite side of the brain to perform specific tasks
- eg. Broca’s area damaged on left side, right side equivalent would carry out its function

Question 14

what does functional recovery imply about lateralisation

Answer 14

function is not always lateralised to specific hemispheres

Question 15

supporting evaluation for plasticity

Answer 15

1. research support, Maguire and Draganski
2. animal study support, Hubel and Wiesel

Question 16

Hubel and Wieser

Answer 16

sewed one eye of a kitten shut
- analysed brains cortical responses
- found area of visual cortex associated w shut eye was not ilde, but continued to process info from the open eye
CA - careful when extrapolating to humans

Question 17

opposing evaluation for plasticity

Answer 17

negative plasticity

Question 18

negative plasticity

Answer 18

E - 60-80% of amputees have been known to develop phantom limb syndrome
E - these sensations are painful and thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss (Ramachandran and Hirstein)
CA - unique case, not generalisable
L - brains ability to rewire itself can sometimes have maladaptive behavioural consequences