Plasticity and functional recovery

• What is plasticity?

  The ability of the brain to change and adapt, modifying its own structure and function as a result of experience - neural connections can form at any age
• Functional recovery of the brain

  • Following physical injury or stroke, unaffected areas of the brain often adapt and compensate for the damaged areas
  • This happens because the brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage. Dormant synapses that wouldn't typically be used to carry out certain functions are activated / 'unmasked' to enable functioning to continue.
  • Stem cells are also used to provide treatments
• What are stem cells?

  Stem cells are undifferentiated cells that have the ability to develop into different types of specialised cells in the body - including neurones
• What did Elbert (1985) research into plasticity in violinists?

  • They rely on extraordinary finger dexterity in their left hand, much less required on the right hand used for bowing
  • Brain scans of the somatosensory cortex in violinists revealed an unusually large region devoted to the fingers movement of the left hand, compared to the right
  • The asymmetry suggests the brain has responded to the demands placed upon it, adapting by recruiting neurones to help support finger control in the left hand
• What did Maguire (2000) research into plasticity in taxi drivers?

  • London taxi drivers require a thorough knowledge of streets and traffic patterns so they can effectively navigate the challenging layout in London streets
  • Brain scans of 16 London taxi drivers showed a particularly large posterior hippocampus, a region that supports two dimensional spatial processing (high demands on long term memory and spatial reasoning)
  • The posterior hippocampus was largest in taxi drivers with more than 40 years of experience
• What did May (2004) research into plasticity in juggling?

  • Divided a group of 24 non-jugglers into two groups, 12 learnt how to juggle and other 12 used as a control group
  • Brain scans taken before and after learning showed changes in regions specific to visualisation in the temporal lobes, 3% increase in volume (small but measurable quantity)
  • Control group - no change
  • Three months later, brain scans showed the structural change had partially reversed -> human brain's macrostructure can change in direct response to level of training
• Practical application in theory of plasticity

  • Contribution to neurorehabilitation
  • Spontaneous recovery slows down after a number of weeks following illness or injury, so physical therapy is required to maintain improvements
  • Movement therapy and electrical stimulation are used to counter the deficits in motor / cognitive functioning after a stroke
  • This shows that although the brain has capacity to recover itself to a point, the process requires further intervention to be successful
• What is negative plasticity?

  • Maladaptive behavioural consequences due to the brain's ability to rewire itself
  • Prolonged drug use results in poorer cognitive functioning as well as an increased risk of dementia
  • 60% - 80% of amputees experience phantom limb syndrome
• What is phantom limb syndrome?

  Perception of sensations or pain in a limb that has been amputated, unpleasant and painful, due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss
• What is the relationship between age and plasticity?

  Functional plasticity tends to reduce with age - brain has a greater propensity for reorganisation in childhood as it is constatnly adapting to new experiences and learning
• What did Ladina Bezzola (2012) demonstrate about neural plasticity?

  • 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 efficient neural representations after training
  • This shows that neural plasticity does continue throughout the lifespan
• How did animal studies support the idea of plasticity?

  Hubel and Wiesel (1963) sewed one eye of a kitten shut and analysed the brain's cortical responses, they found that the area of the visual cortex associated with the shut eye with not idle but continued to process information from the open eye -> plasticity
• Education and plasticity 'Cognitive reserve'

  Eric Schneider (2014) discovered that the more time brain injury patients spent in education, the greater their changes of a disability-free recovery (DFR)

  40% of patients studied who achieved DFR had more than 16 years of education, whereas 10% of patients who did not achieve DFR had less than 12 years of education
• What are three types of functional recovery?

  • Recruitment of homologous areas
  • Axonal sprouting
  • Reformation of blood vessels
• Recruitment of homologous areas

  Using the opposite hemisphere to perform functions that are damaged on the other hemisphere
• Axonal sprouting

  Growing new nerve ending to join undamaged neurones and create new pathways
• Reformation of blood vessels

  Supporting and reinforcing new neural pathways with blood vessels