Plasticity + functional recovery

• What is plasticity?

  The brains ability to modify, change and adapt its structure + function from experience
• What was the old way of thinking?

  Brain function was fixed and unable to adapt after childhood
• What are the three factors affecting plasticity?

  1. Life experience
  2. Video games
  3. Meditation
• How does life experience affect plasticity?

  • cognitive function decreases with age, but plasticity can still happen throughout the lifespan
  • Research on 60 year 60-year-olds juggling -> increased grey matter in visual cortex
  • If learning is stopped, the changes are reversed (’don’t use it, lose it’)
• How do video games affect plasticity?

  • lead to greater synaptic connections needed for motor and visual functioning
  • Research- Kuhn -increased grey matter in cortex, cerebellum and hippocampus when playing video games
  • Key in practicing spatial awareness and motor skills
• How does meditation affect plasticity?

  • increases gamma waves associated with high synaptic and neuron connection
  • Davidson studied meditating monks
  • Found them to have high levels of gamma wave activity compared to control group
  • Short and long term benefits
• What is functional recovery ?

  Functions can be moved/taken over by an undamaged area of the brain after trauma or injury
• What is meant by spontaneous recovery?

  recover some function quickly after damage but this slows after some time, which is when we begin to introduce the individual go rehabilitation therapy
• What are the two methods that contribute to functional recovery?

  1. Neural masking
  2. Stem cells
• What is neural masking?

  • dormant synapses open themselves to new connections
  • Allows compensation for nearby damage
• How are stem cells used in functional recovery?

  • unspecialised cells
  • Can directly replace / take over the function of dead cells
  • Can help repair injured cells
  • Can bridge a gap between/ provide a link between dying and new cells
• How does re-writing happen?

  1. Axon sprouting
  2. Denervation supersensetivity
  3. Recruitment of homologous areas
• What is Axon sprouting?

  New nerve endings allow connection to undamaged cells - creates new neural pathways
• What is denervation supersensitivity?

  Axons that already do a similar job become active to compensate for the loss of function
• What is the recruitment of homologous areas?

  The equivalent area on the undamaged part of the brain takes over functioning
• Strength of plasticity - research support (rats)

  • Kempermann
  • Rats housed in complex, stimulating environment vs a plain lab cage
  • Those in the complex cage had more new neural connections and neurons
  • Supports the idea of learning and life experience in adapting the brain
• Weakness of plasticity - rats (counter point)

  • rats lack higher order thinking and complex emotions that humans have
  • This could mean that we wouldn’t experience the same changes
  • Rats are also much smaller, so may have key differences in brain structure
  • Therefore, this research isn’t generalisable to humans
  • We can't ethically manipulate the came variables in human studies so can't establish validity
• Strength of plasticity - taxi drivers

  • research support using empirical MRI evidence
  • Increased grey matter in the posterior hippocampus associated with skills for spatial awareness and motor coordination
  • Taxi drivers have to remember 20,000 + streets in London
  • Supports the notion of Kuhn’s research for videogames and how practicing those skills helps the brain
  • Consistent results = reliable
• Weakness of plasticity - taxi drivers studies

  • small sample size
  • Drivers are usually men and may have entered the profession as they were already food at spatial memory = not generalizable
  • So we can't be sure that the difference is due to knowledge as they weren't tested before training and years of experience
  • Confounding variables may have impacted the internal validity - possible the drivers had other life skills or experiences of genetic differences
  • = research is less generalizable
• Strength of functional recovery- neural adaptation

  • Schneider et al
  • Patients with damaged brain areas were 7x more likely to have regained function / be disabikith free only 1 year after trauma IF they had a higher level of educational achievement
  • Higher educational attainment = greater cognitive reserve which is needed for neurons to take over / compensate for functioning
  • Shows how neurons can adapt - evidence of functional recovery and supports the role of re-writing
• Weakness of functional recovery - correlation doesn't = causation

  • Schneider et al
  • Other factors may have impacted recovery such as quality/ standards of care acted trauma or there may be differences due to the type of trauma experienced and exact area of the brain injury
• Weakness of functional recovery - other credible theories

  • lateralisation/localisation - suggest that the concept of recruitment of homologous areas isn't possible for certain functions (e.g. Language centres)
  • Maybe fr is too optimistic and is trying to explain unique cases of regained function that isn’t representative of the wider population
  • Fault in the theory - we all have neurons so why can't everyone’s brain rexerite after trauma? Suggests it is incomplete and doesn't account for factors of individual differences
• Strength of functional recovery - other theories

  • there is case study evidence that functional recovery does happen so the theory does hold some relevance to real experience
  • J.W. (patient) developed the capacity for language out of right hemisphere after damage, even though other theories would dispute this happening