Plasticity and functional recovery of the brain after trauma

• What is plasticity?


  This describes the brain's tendency to change and adapt as a result of experience and new learning.
• As we age, rarely used synaptic connections are deleted and frequently used connections are strengthened - a process known as synaptic pruning.
• Research into plasticity:


  Maguire et al. studied the brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group. This part of the brain is associated with the development of spatial and navigational skills in humans. As part of their training, London cabbies must take a complex test called 'The Knowledge', which assess their recall of the city streets and possible routes.
• The functional recovery that may occur in the brain after trauma is another example of neural plasticity. Healthy brain areas may take over the functions of those areas that are damaged, destroyed or even missing.
• What happens in the brain during recovery?

  1. Axonal sprouting.
  2. Reformation of blood vessels.
  3. Recruitment of homologous (similar) areas to perform specific tasks.
• AO3 - Practical application:

  Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation. Following injury to the brain, spontaneous recovery tends to slow down after a number of weeks so forms of physical therapy may be required to maintain improvements in functioning. This shows that this process requires further intervention if it is to be completely successful.
• AO3 - Negative plasticity:

  60-80% of amputees have been known to develop phantom limb syndrome - the continued experience of sensations in the missing limb as if it were still there. These sensations are usually unpleasant and are though to be due to cortical reorganisation in the somatosensory cortex. This shows that the brain's ability to rewire itself can sometimes have maladaptive behavioural consequences.
• AO3 - Age and plasticity:

  Bezzola et al. demonstrated how 40 hours of golf training produced changes in the neural representation of movement in participants aged 40-60. Using fMRI, the researchers observed reduced motor cortex activity in the novice golfers compared to a control group, suggesting more effective neural representations after training. This suggests that neural plasticity does continue throughout the lifespan.
• AO3 - Support from animal studies:

  A study by Hubel and Wiesel involved sewing one eye of a kitten shut and analysing the brain's cortical responses. It was found that the area of the visual cortex associated with the shut eye was not idle but continued to process information from the open eye.