Plasticity and functional recovery

• What is plasticity?

  • The ability of the brain to change through life by growing new connections as a result of experience and new learning
  • Our brain has thousands of synaptic connections during infancy - as we grow older our rarely-used connections get deleted and frequently-used connections are strengthened, known as synaptic pruning
• What research is there into plasticity?

  • Maguire et al. (2000): calculated the amount of grey matter in the brains of London taxi drivers
  • Found the posterior hippocampi (area associated with spatial and navigational skills) was significantly larger than control group
  • Showed a positive correlation - the longer they had spent as a taxi driver, the larger their posterior hippocampus in volume, supporting the idea that their learning experience with roads and shortcuts had altered the structure of their brains
• What other research is there into plasticity?

  • Draganski et al (2006): reviewed brain images of medical students 3 months before and after their final exams
  • Learning-induced changes seemed to have occurred in the posterior hippocampus and parietal lobe, supporting the idea that the brain can change throughout life depending on its' experience and learning
• What is one strength of plasticity?

  • Life-long ability: Bezzola et al. (2012) found that in participants aged 40-60, 40 hours of golf-training produced changes in the neural representations of movement in their brains
  • Researchers also found increased motor cortex activity in the fMRIs of the new golf group compared to the old group, suggesting more efficiency after training
  • Shows neural plasticity can continue throughout the lifespan rather than just a result of deleting rarely-used connections from infancy
• What is one limitation of plasticity?

  • Negative plasticity: Medina et al. (2007) has found evidence that the brain's adaptation to prolonged drug use leads to poorer cognitive functioning in later life and an increased risk of dementia
  • Ramachandran and Hirstein (1998): 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
  • Sensations are painfully unpleasant and thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss
  • Suggests the brain's ability to adapt to damage isn't always beneficial
• What is another strength of plasticity?

  • Research support: Kuhn et al found an increased amount of grey matter in the brains of participants who played video games for 30 minutes a day over 2 months
  • Davidson et al. found that Buddhist monks who meditated frequently had a greater activation of gamma waves (which co-ordinate neural activity) compared to a control
  • Studies highlight the idea of plasticity and the brain’s ability to adapt as a result of new experience
• What is functional recovery?

  • A form of plasticity where following damage through trauma, healthy, unaffected areas of the brain are often able to adapt and take over the functions of those areas that are damaged
  • This can occur quickly after trauma then slow down after several weeks/months
• What happens in the brain during recovery?

  • Brain can rewire or reorganise itself by forming new synpatic connections close to the area of damage
  • Secondary neural pathways that aren't typically used are activated or 'unmasked' to enable functioning to continue
• What are 3 structural changes in the brain that support functional recovery?

  • Axonal sprouting - growth of new nerve endings that connect with other undamaged nerve cells to form new neuronal pathways
  • Denervation super-sensitivity - when axons that do a similar job become aroused to a higher level to compensate for the ones that are lost
  • Recruitment of homologous (similar) areas: specific lateralised tasks can still be performed by having the other side carry out its functions e.g. if Broca's area was damaged the right-sided equivalent would carry out its functions of language comprehension
• What is one strength of functional recovery?

  • Real-world application: understanding the processes involved in plasticity has contributed to the field of neurorehabilitation
  • Constraint-induced movement therapy is used to help stroke patients by having them repeatedly practice using the affecting part of their body while the unaffected arm is restrained to support axonal growth
  • Shows research into functional recovery is useful as it helps medical professions know when interventions are to be made
• What is one limitation of functional recovery?

  • Cognitive reserve: a person's level of education may affect their recovery rates
  • Schneider et al. (2014) found that the more time people with a brain injury had spent in education (their 'cognitive reserve') meant they had a greater chance of a disability-free recovery
  • 40% of those who achieved DFR had over 16 years of education compared to 10% who had less than 12 years
  • Implies people with brain damage who have a lower cognitive reserve are less likely to achieve a full recovery
• What is another limitation of functional recovery?

  • Deteriorates with age: Elbert et al. concluded that the capacity for neural reorganisation is much greater in children than in adults which explains why adults find change more demanding than do young people
  • This means that neural regeneration is less effective in older brains, suggesting we must consider individual differences such as age when assessing the likelihood of functional recovery in the brain after trauma