Plasticity and functional recovery

• Neuroplasticity


  brains ability to change and adapt in response to experiences
• In first few years brain grows rapidly
• As each neurone matures, sends out multiple branches which increases number of synaptic connections from neurone to neurone.
• At birth each neurone has about 2500 synapses.

  At 3 years old it increases to 15,000.
• Neural Pruning


  As we mature, connections we dont use are deleted whilst ones we do use are strengthened.

  This continues throughout our life.
• Maguire


  Investigated 16 London Taxi drivers.

  Found had more vol of grey matter in posterior hippocampus than cntrl grp.

  This area of brain involved in STM and spatial navigation.
• Mechelli


  Found that learning second language increases density of grey matter in left inferior parietal cortex.

  Amount of changes to brain structure depends on fluency of lang and age started learning it.
• After brain injury, e.g. stroke, unaffected brain areas can take over and carry out functions of affected areas.
• Can be fast in first few years - spontaneous recovery stage.

  But after slows down.
• Can be helped by rehabilitation.

  Nature of these programs vary with type of injury, e.g. can retrain movement or do speech therapy.
• Hart found recovery slows with age and is influenced by severity of impairment by injury.
• Scheider


  Carried out retrospective study of 769 ps.

  Had moderate - severe brain injuries.

  Found those with college education 7x more likely to achieve disability free recovery compared to high school dropouts.
• During brain recovery period, brain rewires and reorganises itself.

  Forms new synaptic connections avoiding damaged areas.
• Existing neural pathways that are inactive/used for other purposes take over and carry out lost function.
• Brain reorganisation happens thru mechanism e.g. Axonal Sprouting.
• Axonal Sprouting


  where undamaged axons grow new nerve endings to reconnect neurones whose links severed by damaged.
• Undamaged axons sprout new nerve endings and connect with other undamaged nerve cells.

  Thus making new links and neural pathways to accomplish what was once a damaged function.
• Recruitment of homologous areas


  Even though each hemisphere responsible for own function, if one damaged the intact one can take over some of its functions.