Plasticity & Functional Recovery of Brain

Question 1

Brain Plasticity - Life Experience

Answer 1

1) Synaptic Pruning –> As we age, rarely-used connections are deleted/weaken & frequently-used connections are strengthened.
2) Neural connections can change & be formed (plasticity) at any time, due to learning & experience.

Question 2

Maguire et al.(2000)

Answer 2

Concept of plasticity is supported by a taxi driver study.

1) Found significantly more volume of grey matter in the posterior hippocampus in London taxi drivers than in a matched control group - this part of brain is linked with development of spatial & navigational skills.

2) London cabbies take a complex test as training to assess their recall of city streets & routes –> this learning experience appears to alter the structure of their brains & the longer they had been on the job, the more pronounced the structural difference was.

3) Found a positive correlation between the size of the posterior hippocampus and the time spent taxi driving.

Question 3

Draganski et al.(2006)

Answer 3

Concept of plasticity is supported by research on learning.

1) Imaged brains of medical students 3 months before & after final exams.
2) Learning-induced changes were seen in posterior hippocampus & the parietal cortex, presumably from learning for the exam.

Question 4

Khun et al (2014)

Answer 4

1) Compared a control group with a video training group who were trained for 30 minutes per day on a game.
2) Found a significant increase in grey matter in various brain areas. This was not evident in the control group who did not play the game.

3) Concluded that video game training resulted in new synaptic connections in brain areas involved in special navigation, strategic planning, working memory & motor performance.

Question 5

Limitation of Plasticity

Answer 5

POSSIBLE NEGATIVE BEHAVIOURAL CONSEQUENCES

1) 60-80% of amputees have phantom limb syndrome - experiencing sensations in missing limbs due to changes in somatosensory cortex.
–> Suggests brain’s ability to adapt to damage isn’t always beneficial & may lead to physical & psychological problems.

Question 6

Functional Recovery

Answer 6

1) Functional recovery of brain after trauma is an important example of neural plasticity - healthy brain areas take over functions of areas damaged, destroyed or missing.

2) Neuroscientists suggest this process occurs quickly after trauma (spontaneous recovery) & then slows down.

Question 7

Brain ‘Rewires’ Itself

Answer 7

1) Brain rewires & reorganises itself by forming new synaptic connections close to damaged area.

Question 8

Structural Changes in the Brain

Answer 8

Further Structural Changes:

1) Axonal Sprouting - growth of new nerve endings which connect with other undamaged cells to form new neuronal pathways.
2) Denervation Supersensitivity - axons that do a similar job become aroused to a higher level to compensate for the ones that are lost.
3) Recruitment of Homologous (similar) Areas - the opposite side of the brain takes over specific tasks (e.g. language production).

Question 9

Mechanisms For Recovery

Answer 9

1) Neuronal Unmasking:
Wall (1977) identified ‘dormant synapses’ in the brain. The unmasking can open connections to regions of the brain that aren’t normally activated, which in time allows the development of new structures.

2) Stem Cells:
Unspecialised cells that have the potential to give rise to different cell types that carry out different functions.
- Stem cells implanted into the brain can replace dead or dying cells.
- Secrete growth factors that somehow ‘rescue’ the injured 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 10

Strength - Functional Recovery

Answer 10

REAL-WORLD APPLICATION

1) Understanding brain plasticity has led to neurorehabilitation - understanding axonal growth encourages new therapies.
2) E.g. constraint-induced movement therapy involves mass practice with an affected arm while unaffected arm is restrained.
–> Shows research into functional recovery helps medical professionals know when interventions can be made.

Question 11

Limitation - Functional Recovery

Answer 11

NEURAL PLASTICITY MAY BE RELATED TO COGNITIVE RESERVE

1) Schneider et al. looked at the time brain injury patients had spent in education (indicated their cognitive reserve) & their chances of a disability-free recovery (DFR).
2) 40% of patients who achieved DFR had more than 16 yrs in education compared to 10% who had less than 12 yrs.
–> Suggest cognitive reserve is a crucial factor in determining how well the brain adapts after trauma.