Plasticity and functional recovery

• Brain plasticity - brains ability to change and adapt as a result of the experience.

  During infancy, brain experiences rapid growth in the number of synaptic connections it has.

  As we age, rarely used connections are deleted and frequently used connections are strengthened - known as synaptic pruning
• Plasticity

  Brains of young children exhibit more plasticity than adults.

  Existing neural connections can change or new neural connections can be formed as a result of learning and experience
• Functional recovery of the brain after trauma

  Following a form of trauma such as stroke, unaffected areas of the brain are able to adapt and compensate for those areas that are damaged.

  Healthy brain areas may take over those areas that are damaged, destroyed or even missing.

  This process can occur quickly after trauma and then slow down after several months.
• What happens during brain recovery?

  The brain is able to rewire and reorganise itself by forming new synaptic connections close to the areas of damage.

  Neural pathways that would not typically be used to carry out certain functions are activated or 'unmasked' to enable functioning to continue.
• Structural changes in the brain:

  • Axonal sprouting
  • Neuronal unmasking
  • Recruitment of homologous areas
• Axonal sprouting

  The growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways.
• Neuronal unmasking

  Dormant synapses were identified in the brain. These are synaptic connections that exist but are ineffective.

  However, increasing the rate of input to there synapses, which would happen when surrounding brain area becomes damaged can the unmask these dormant synapses.

  This can open connections to regions of the brain that are not normally activated creating development of new structures.
• Recruitment of homologous areas

  Opposite side of the brain takes over to perform specific tasks.

  For example if the Broca's area was damaged on the left side of the brain, the right sided equivalent would carry out its functions
• Evaluation - plasticity

  Longitudinal studies can show direct changes. Hyde studied the effects of 15 months of instrumental music training in 6 year olds. There was significant increases in brain tissue in the motor and auditory centres.

  Kuhn et al - found participants that played Super Mario for 30 minutes a day for two months had a large increase in grey matter in various brain areas. The game had improved their spatial navigation, strategic planning and working memory and motor performance.
• Evaluation plasticity - against

  May have negative behaviour consequences. Research has shown that the brains adaptation to prolonged drug use lead to poorer cognitive functioning in later life as well as increase risk of dementia.

  60-80% of amputees have been known develop phantom limb syndrome, they continued to experience sensations in the missing limb like it was still there. Suggesting the brains ability to adapt to damage is not always beneficial.
• Evaluation - functional recovery

  Tajiri - found rats given transplanted stem cells to the region of the brain affected by injury showed clear development of neuron-like cells 3 months after the injury.

  Practical application - understanding the process involved in plasticity and functional recovery has contributed to the field of neurohabilitation. It is now known that the brain can only fix itself up to a point and that further invention is needed like therapy.
• AO3 - London Taxi drivers (plasticity)

  May have an enlarged hippocampus before they aquire 'The knowledge'.

  Longitudinal studies can show direct changes
• AO3 - Hyde (Plasticity)

  Studied the affects of 15 months of instrumental music training in 6 year olds. There were significant increases in brain tissue in the motor and auditory area. Those with the biggest changes showed the greatest improvements
• AO3 - Zattore (Plasticity)

  Reviewed the research on the effects of musical training on the brain and found they were greater among children and young adults than older adults suggesting plasticity reduces with age
• AO3 - functional recovery

  Age differences in functional recovery - it is commonly accepted view that functional plasticity reduces with age. According to this view the only option following traumatic brain injury beyond childhood is to develop compensatory behavioural strategies to work around the deficit