Plasticity & functional recovery of the brain after trauma

Question 1

Brain plasticity

Plasticity

Answer 1

Brain has ability to change throughout life
During infancy, brain experiences rapid growth in number of synaptic connections it has, peaking at 15,000 per neuron at 2-3 years (Gopnik et al 1999)
This is 2x as many as in adult brain
As we age, rarely-used connections are deleted and frequently-used connections are strengthened - synaptic pruning
Synaptic pruning allows lifelong plasticity where new neural connections are formed in response to new demands on brain

Question 2

Maguire et al (2000)

Plasticity

Answer 2

Studied brain of London taxi drivers & found sigly more vol of grey matter in posterior hippocampus than in matched CG
This part of brain is associated w/ development of spatial & nav skills in humans & other animals
As part of training, London cabbies take complex test (The Knowledge) which tests their recall of city streets & poss routes
Also found that longer taxi driver had been in job, more pronounced the structural diff (pos correlation)

Question 3

Draganski et al (2006)

Plasticity

Answer 3

Imaged brains of med students 3 months before & after final exams
Learning-induced- changes were seen to have occured in posterior hippocampus & parietal cortex as result of learning

Question 4

Evaluation: Negative plasticity

Plasticity

Answer 4

Limit: may have negative behavioural consequences
Evidence shows the brain’s adaptation to prolonged drug use leads to poorer cog functioning in later life & increased risk of dementia (Medina et al, 2007)
60-80% of amputees develop phantom limb syndrome
This is unpleasant, painful & thought to be due to cortical reorganisation in somatosensory cortex that occurs as result of limb loss (Ramachandran & Hirstein)
Therefore, brain’s ability to adapt to damage is not always beneficial

Question 5

Evaluation: Age & plasticity

Plasticity

Answer 5

Strength: brain plasticity may be life-long ability
Bezzola et al (2012) demonstrated how 40 hours of golf training prodcued changes in neural reps of movement in ppts age 40-60
Using fMRI, researchers observed increased motor cortex activity in novice golfers compared to a CG, suggesting mor efficient neural reps after training
Therefore, neural plasticity can continue throughout the lifespan

Question 6

After brain trauma

Functional recovery

Answer 6

Following trauma, unaffected areas of brain are able to adapt & compensate for damaged areas
Neuroscientists suggest this process can occur quickly after trauma & then slow down after several weeks or months
At this point, individual may require rehabilitative therapy to further their recovery

Question 7

What happens in brain during recovery?

Functional recovery

Answer 7

Brain able to rewire itself by forming new synaptic connections close to area of damage
Secondary neural pathways that would not typically be used to carry out certain functions are activated to enable functioning to continue, often in same way as before (Doidge, 2007)

Question 8

Axonal sprouting

Functional recovery

Answer 8

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

Question 9

Denervation supersensitivity

Functional recovery

Answer 9

Occurs when axons that do a similar job become aroused to a higher level to compensate for ones that are lost
However, it can have neg consequence of oversensitivity to messages such as pain

Question 10

Recruitment of homologous areas

Functional recovery

Answer 10

This means specific tasks can still performed
For example, if Broca’s area was damaged on left side of brain, the right-sided equivalent would carry out its functions
After a period of time, functionality may then shift back to the left side

Question 11

Evaluation: Real-world application

Functional recovery

Answer 11

Strength: real-world applications
Understanding the processes involved in plasticity has contributed to field of neurorehab
Simply understanding axonal growth is possible encourages new therapies to be tried
For example, constraint-induced movement therapy for stroke patients where they practise using affected part of their body while unaffacted part is restrained
Therefore, research into functional recovery is useful as it helps medical professionals know when interventions need to be made

Question 12

Evaluation: Cognitive reserve

Functional recovery

Answer 12

Limit: level of education may influence recovery rates
Schneider et al (2014) revealed that more time people w/ brain injury had spent in education, the greater their chances of a disability-free recovery (DFR)
40% of those who achieved DFR had more than 16 years’ education compared to 10% who had less than 12 years
Therefore, people with brain damage who have insufficient DFR are less likely to achieve a full recovery