Plasticity & Functional Recovery

• Brain plasticity refers to the brain's ability to change and adapt as a result of experience.
• Synaptic pruning involves strengthening of regularly used pathways, and deletion of pathways not used.
• Synaptic pruning means that even after childhood, the brain can still create new neural pathways or adapt to new experiences as a result of learning.
• The capacity for the brain to mould and sculpt itself is at its peak in early childhood. (If an entire hemisphere is removed from a child in their early life they can still grown up to have few, if any, behavioural/ cognitive impairments- shows incredible plasticity to rewire).
• • Kuhn et al compared a control group with a video game training group that was trained for 2 months for at least 30 mins per day on the game Super Mario.
  • They found a significant increase in grey matter in various brain areas (cortex, hippocampus, cerebellum), this increase was not evident in the control group that did not play Super Mario.
  • Researchers concluded that video game training had resulted in new synaptic connections in brain areas involved in spatial navigation, strategic planning & motor performance- skills that are important in playing the game successfully.
• • Boyke et al taught PPs a new skill- juggling- and found evidence of neural plasticity in even 60+ year olds.
  • Changes were lost if they stopped practising, which indicates the 'use it or lose it' nature of brain plasticity when older.
  • Neural decline in ageing.
• Brain Plasticity Strength:

  • There's research support for brain plasticity from studies on humans- Maguire et al investigated London cab drivers using MRI scans.
  • Found an increased hippocampus size compared to controls and a positive correlation between this and time spent as a cab driver.
  • Lends support to the validity of the claims about brain plasticity.
• Brain Plasticity Strength:

  • There's research support from studies on animals- Kempermann et al found that the amount of neurons in the brain of rats increased if they were placed in a complex, enriched environments compared to those in basic lab cages.
  • This was particularly evident in the hippocampus- responsible for new memories & spatial awareness.
  • Lends support to validity of the claims about brain plasticity, although there are issues with non-human animal research.
• Functional recovery refers to the brain's ability to regain a particular function even when the dedicated area has been damaged or destroyed (through stroke etc).

  The brain appears to be able to 're-wire' itself so that other sections can take over the lost function- only possible because of the brain's plasticity.
• Research has investigated how functional recovery happens:

  • Neural unmasking- Wall (1997)
  • We have 'dormant' synapses in our brain (not doing a particular job), these can act as 'spares' so that if an area is damaged, the areas around it become activated which unmasks the dormant synapses so they can take on the function that may have been lost.
• Functional recovery may occur through:

  1. Axonal sprouting/ Neural unmasking- undamaged axons grown new nerve endings to reconnect the neurons (links severed through damage). Undamaged axons can sprout new links & neural pathways to accomplish what was a damaged function.
  2. Reformation of blood vessels- facilitates the growth of new neural pathways & body heals.
• Functional recovery may occur through:

  3. Recruitment of homologous areas- an area of the brain has been damaged so the opposite side of the brain may take on those abilities.

  4. Stem cells- unspecialised cells, can become nerve cells & replace ones from the damaged area.
• Functional Recovery Strength:

  • Has lead to advancements in neurohabilitation.
  • Eg, constraint-induced movement therapy (CMT) can be used when motor control on one side of the brain has been lost.
  • By constraining the working limb, the patient is forced to use the affected one- allowing the brain to make new connections.
  • Gives credibility to the theory as it can be used to help improve lives.
• Functional Recovery Weakness:

  • There's evidence that individual differences mediate functional recovery- such as age.
  • Elbert et al demonstrated that the capacity for neural rewiring following trauma is much greater in children than in adults.
  • Children recover quicker & with less long term loss of function.
  • In studies of soldiers with brain damage, 20 year olds had better recovery rates than over 26 year olds (Kapar 1997).
  • Indicates that the capacity for functional recovery is not universal in humans.
• Functional Recovery Weakness:

  • There's evidence that individual differences mediate functional recovery- level of education prior to damage.
  • Schneider et al (2014) found that following brain injury, recovery within one year was 7 times more likely if the patient had a degree level education compared to those who didn't complete high school with any qualifications.
  • This may have important repercussions for rehabilitation workers.
• Functional Recovery Strength:

  • There's research support for functional recovery with stem cells from studies on animals.
  • Tajiri et al transplanted stem cells into the damaged areas of rat's brains. A control group just received a solution infusion, and after 3 months the first group showed development of new neuron cells in the area of injury.
  • Indicates the importance of stem cells in the brain's recovery from damage.