Plasticity and functional recovery

• What is plasticity?

  • Plasticity is the brain’s tendency to change and adapt its structure and function as a result of experience and new learning.
  • Researchers used to believe that changes in the brain only took place during infant and childhood
  • Recent research used to believe that changes continue to create new neural pathways and alter existing ones as a result of learning.
  • The more a person performs an activity, the more neural connections are formed in the area of the brain responsible.
• Who did the study on taxi drivers?

  • London taxi drivers must undertake special training that takes about 2 years to complete, during which time they must learn the roads and routes to an extent that they can navigate their way around central London without a map.
  • This learning period is called being “on the knowledge”.
  • On this basis, Maguire et al (2000) hypothesised that fully licensed London taxi drivers will have structural differences in their hippocampus as a part of this learning experience
• Procedure of Maguire's study?

  • 16 healthy but right-handed male licensed London taxi drivers with a range of years’ experience driving were compared to a control group of 50 healthy right-handed males who did not drive taxis.
  • The mean age of the taxi drivers was 44 and the range of ages was 32-62.
  • Using an MRI scanner, the researchers calculated the amount of grey matter in the participant’s brain.
• Findings of Maguire's study?

  • Taxi drivers had more grey matter in the posterior hippocampus than the control group, therefore the left and right hippocampus had significantly higher volume in taxi drivers’ brains.
  • They also found a positive correlation between the volume of the hippocampus and time spent as a taxi driver that could not be accounted for by age differences. 
• Conclusion of Maguire's study?

  • The hippocampus is associated with memory and development of spatial skills
  • Therefore in taxi drivers there is a redistribution of grey matter in the hippocampus as a result of intense development and use of spatial memory skills, specifically those relating to learning and remembering routes.
  • Therefore, the environment can influence brain structure supporting the idea of plasticity.
• Supporting evidence for plasticity?

  • Supporting evidence for plasticity occurring in other situations comes from Kuhn et al (2014) who compared a control group from a videogame trained for two months for at least 30 minutes a day on Super Mario.
  • They found a significant increase in grey matter in the Super Mario group in various brain areas including the cortex, hippocampus and cerebellum.
  • The researchers concluded that video game training resulted in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance - skills that were important in playing the game successfully 
• Supporting evidence in terms of Draganski?

  • Draganski (2006) also did a study on the brain where he imaged the brains of medical students 3 months before their exams and after their exams, he found a notable increase in the volume of the posterior hippocampus due to the exam. 
• Real life implications of plasticity??

  • Research into plasticity has positive implications in real life from understanding the effects of the environment on the brain.
  • The brain's ability to rewire itself can have negative behavioural consequences which is called negative plasticity.
  • Prolonged drug use for example, is shown to result in poorer cognitive functioning as well as an increase in risk of dementia in life.
  • Therefore, understanding the process of plasticity means advice and treatment can be developed such as rehabilitation, meaning that we can better treat patients who experience negative effects of their environment.
• What is functional recovery?

  • This is a form of plasticity and it is the ability of the brain to redistribute functions after trauma from a damaged area to a non damaged area.
  • This trauma could be caused from a stroke or an accident from brain damage. 
  • Neuroscientists have suggested that the process can occur quickly after a trauma (spontaneous recovery) but it can then slow down after a few months or weeks.
  • After this, rehabilitative therapy is needed to allow the process to further occur. 
  • One way in which the brain is able to recover is through neuronal activation and stem cells: 
• What is neuronal activation?

  • The brain can reorganise itself by forming new synaptic connections close to the damaged area.
  • Instead, secondary neural pathways that are not usually used to carry out the functions are activated to enable the damaged functioning to continue.
  • This process is supported by a number of structural changes: 
• What are some of the structural changes provided for functional recovery?

  • Axonal sprouting - the growth of new nerve endings which connect with other undamaged nerve cells to form a new neural pathway
  • Circulation - Reformation of blood vessels
  • Mirroring - Recruitment of similar areas on the opposite side of the brain, if Broca’s area is damaged in the left hemisphere, it will go to the right hemisphere instead.
• Neuro-rehabilitation real life implication?

  • Understanding the processes of plasticity and functional recovery has led to improvements to the field of neuro-rehabilitation.
  • For example, spontaneous recovery tends to stop after a few weeks or months, which is why rehabilitative therapy is needed to encourage further recovery.
  • Some examples of this therapy can be electrical stimulation or movement therapy, which counter deficits in motor/cognitive functioning.
  • It shows that even though the brain has the capacity to fix itself, it requires further intervention to carry on the process.
• What is a disadvantage regarding individual differences for functional recovery?

  • One disadvantage of functional recovery is that it cannot apply to everyone equally as there are individual differences within the functional recovery.
  • For example, evidence suggests that those who have educational attainment affects how the brain will recover after an accident.
  • University graduates were 7x more likely to be disability free after a moderate to serious injury than those people who did not finish high school.
  • Therefore, this suggests that educational attainment could play a part in functional recovery. 
• Positive evaluation of plasicity?

  • There are thought to be age differences with plasticity; recovery and functional plasticity reduce with age.
  • The brain has a greater ability to reorganise in childhood as it is constantly adapted with new experiences and learning.
  • However, it has also been shown that 40 hours of golf training produced changes in the neural representation of movement in participants aged 40-60.
  • This shows that neural plasticity does continue through the lifespan.
  • Although it has been argued that the capacity for neural reorganisation is greater in children, adults still have the capability of producing changes. 
• Negative evaluation regarding animals?

  • However, most research on plasticity and functional recovery uses animals so we may not be able to generalise it to human plasticity.
  • We have a much higher cognitive functioning with a much more developed cerebrum for example, which is 3mm thick, meaning it contains more neural pathways compared to animals.
  • Therefore, plasticity could be different in animals and humans.