plasticity and functional recovery of brain

• What is meant by brain 'plasticity'.

  Refers to the brain's ability to change and adapt (in terms of function and structure as a result of experience and learning) because of experience

  
• What is functional recovery?

  An example of neural plasticity - the transfer of functions from a damaged area of the brain after trauma (eg stroke) to other undamaged areas to compensate for damage
• (E) Why do children have maximum plasticity?

  To organise all the new information they're developing. Having twice as many synaptic connections than in adulthood
• What is synaptic pruning?

  as we grow older, weak neural connections are broken while strong ones are reinforced, increasing the efficiency of our brains.

  
  

  Research has demonstrated that the brain continues to create new neural pathways and alter existing ones in response to changing experiences
• What is maladaptive plasticity?

  Plasticity resulting in negative consequences.

  
  

  E.G. prolonged drug use causing poorer cognitive function, older age being associated with dementia. Both are due to changes in the brain

  
  

  •Also, 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, painful and are thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss. An error occurs in this rewiring sending faulty messages.
• Outline Maguire et al (2000) taxi driver study.


  (Matched pairs study matched on age and gender) Studied taxi drivers' brains using MRI. Found significantly more grey matter in posterior hippocampus of taxi drivers than control group, which plays a role in human spatial memory and navigational skills. London taxi drivers must do complex test - The Knowledge - which assess their recall of the streets and other possible routes. It is also noteworthy that the longer they had been doing the job the more pronounced was the structural difference (a positive correlation).
• (AO3)What are some issues with Maguire's research into plasticity?

  - Taxi drivers weren't tested before meaning they could've had an already existing difference so can't be sure difference is down to knowledge. However positive correlation between experience and structure makes this less likely

  
  

  - Some psychologists argue research is biologically reductionist and only examines single biological factors in relation to spatial memory. Approach is limited and fails to take into account all different biological/cognitive processes in spatial navigation potentially limiting our understanding.
• (AO3)What are some strengths of the notion of brain plasticity?

  - Supported by research from Maguire et al. (2000) taxi study however is criticised as being biologically reductionist. The research shows that the brain can permanently change in response to frequent exposure to a particular task supporting theory of brain plasticity. Other research includes Kuhn et al (video games) and Davidson et al. (meditation)

  
  

  - Practical application: Contributed to field of neurorehabilitation.

  
  

  - Support from animal studies - early evidence of neuroplasticity and functional recovery was derived from animal studies. Hubel and Wiesel (1963) involved sewing one eye of kitten shut and analysing brains cortical responses. was found that the area of the visual cortex associated with the shut eye was not idle but continued to process info from open eye, supporting plasticity.
• Briefly outline the research by Kuhn and Davidson in to plasticity.

  - More research: Kuhn et al. found significant increase in grey matter in various regions of the brain after participants played video games for 30 min a day over 2 month period. Davidson et al. demonstrated the permanent change in brain generated by prolonged meditation: Buddhist and monks who meditate frequently had a much greater activation of gamma waves (which coordinate neural activity) than students with no experience of meditation. Two studies highlight idea of plasticity and brains ability to adapt as a result of new experience
• Outline the practical application of plasticity research.

  From research in to understanding the process involved in plasticity it has contributed to neurorehabilitation:

  
  

  Following illness or injury to the brain, spontaneous recovery may slow down so forms of physical therapy may be required to maintain improvements in functioning. E.g. electrical stimulation, movement therapy to counter deficits in motor or cognitive functioning.

  This shows although brain may have capacity to 'fix itself' to a point this process may require intervention to be completely successful. neurorehabilitation demonstrates the positive application of research in this area to help improve the cognitive functions of people suffering from injuries.
• What are the 4 types of functional recovery?

  Neuronal unmasking

  Axonal sprouting

  Reformation of blood

  Recruitment of homologous areas
• Explain what neuronal unmasking is?

  When dormant neurons (not had enough input to become active) open connections to compensate for nearby damaged areas.

  
  

  The brain is able to rewire and organise itself by forming new synaptic connections close to the area of damage. Secondary neural pathways not typically used to carry out certain functions are unmasked to allow function to continue
• What is axonal sprouting?

  Undamaged axons 'sprouting' (growing) nerve endings and connect with other undamaged nerve cells and reconnect to neurons where connection was damaged/severed, therefore making new links and new neural pathways to accomplish what was a damaged function.
• Explain the process of 'recruitment of homologous areas in functional recovery.

  Recruitment of similar areas on opposite side of brain

  
  

  E.G. if brocas area was damaged then a similar area on the right side of brain would carry out its functions for a period of time until left side recovers if it does
• What is meant by reformation of blood vessels in functional recovery?

  Damaged blood vessels are reformed to ensure the brain functions in affected areas
• What are some strengths of research in to functional recovery?

  - Supported by animal studies: Taijri et al. (2013) found stem cells provided to rats after brain trauma showed a clear development of neuron like cells in area (neuronal unmasking). Stream of stem cells migrated to injury area - not the case with control group

  
  

  - Supported by human studies: human echolocation can be learned for humans to sense their environment - specifically used by some blind people to navigate environment and sense their surroundings. 2010+11 studies using fMRI show parts of brain associated with visual processing adapted for echolocation - supports neuroplasticity and functional recovery (navigation). However, small scale studies meaning could be down to individual difference

  
  

  - Evidence that a persons education attainment influences how well the brain functionality adapts after injury - Eric Schneider et al (2014)
• (AO3)What is a pro and con of Tariji et al. (2003) research into functional recovery with the use of stem cells?

  + Animal studies enable us to monitor function of brain before and after trauma which ethically could not be done on humans or impossible (if naturalistic)

  
  

  - Animal studies limited in generalisation to humans: rat brains are smaller and less complex but to counter the two brains are very similar in structure and function
• What factors may influence how well a person recovers from a brain injury?

  Severity of injury

  Where the injury was

  Age

  How quickly they are treated

  How they respond to treatment

  Any other pre existing conditions

  cognitive reserve
• What is meant by cognitive reserve?

  ?????? TBC
• Outline the research conducted by Eric Schnieder et al. in 2014 on functional recovery.

  Eric Schneider et al (2014) discovered that the more time brain injury patients had spent in education - which was taken as an indication of their 'cognitive reserve' - the greater their chances of a disability free recovery

  
  

  Two-fifths of patients studied who achieved disability free recovery had more than 16 years education compared to about 10% of patients who had less than 10 years of education

  
  

  The researchers concluded that 'cognitive reserve' (associated with greater educational attainment) could be a factor in neural adaptation during recovery from traumatic brain injury.
• (AO3) Outline a debate relating to functional recovery.


  •There are individual differences in how we recover from brain trauma. Particularly age differences in functional recovery - it is possible that this ability can deteriorate with age

  
  

  It's a commonly accepted view that functional plasticity reduces with age (Huttenlocher, 2002). According to this view, the only option following traumatic brain injury beyond childhood is to develop compensatory behavioural strategies to work around the deficit (such as seeking social support or to develop strategies to deal with cognitive deficits).

  
  

  However, studies have suggested that even abilities commonly thought to be fixed in childhood can still be modified in adults with intense retraining. Despite these indications of adult plasticity, Elbert et al (2001) concluded that the capacity for neural reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains.

  
  

  This may explain why adults find change more demanding than do young people.

  Therefore, we must consider individual differences when assessing the likelihood of functional recovery in the brain after trauma.
• negative plasticity

  P: limitation - may have negative behavioural consequences

  E: brains adaption to prolonged drug use leads to poorer cognitive abilities later and increased risk of dementia

  E: 60-80% of amputees develop phantom limb syndrome

  L: therefore brains ability to adapt to damage may not be beneficial
• age and plasticity

  P: strength - brain plasticity may be long-term ability

  E: 40 hours of golf training produced changes in neural representations of movement in ppt aged 40-60

  E: researchers observed increased motor cortex activity in novice golfers compared to a control group

  L: therefore neural plastcity may continue life-long
• real-world application - functional recovery

  P: strength - real-world application

  E: understanding axonal growth is possible has led to new therapies being tried

  E: e.g. costrait-induced movement therapy used with stroke patients whereby their practice using their affected limb while their unaffected limb is restrained

  L: therefore helps medical professionals know when interventions are needed
• cognitive reserve - functional recovery

  P: limitation - level of education may influence recovery rates

  E: those with a brain injury that have been in education for longer are more likely to have a disability-free recovery

  E: 40% of those who achived a DFR spent more than 16 yrs in education compared to 10% who spent less than 12 yrs in education

  L: therefore this suggests that people who have insufficient DFR are less likely to achieve a full recovery