Brain plasticity + Functional recovery

• Brain Plasticity


  the idea that the brain is malleable so that it can flex and change shape

  it has the ability to create and lose connections
• Synaptic Pruning


  connections that are frequently used are strengthened

  connections that aren't used are deleted
• Draganski et al (2004)

  compared students 3 months before exams and then after (repeated measures)

  showed increased connections in hippocampus and parietal lobes after the exam
• Functional Recovery

  physical injury such as illness or stroke

  areas that haven't been damaged will try to compensate

  this often occurs rapidly after injury but slows in time

  brain strengthens different pathways and reforms blood vessels
• Axonal Sprouting


  growing new nerve endings to connect else where
• Recruitment of Homologous Areas

  using a similar area of the brain in the opposite hemisphere
• Plasticity and Functional Recovery Evaluation

  neuro-rehabilitation and therapy

  education e.g revision

  functional changes reduces with age
• Medina et al (2007)

  prolonged drug use leads to a lack of connections and risk of dementia
• Romachandlan and Hirstein (1998)

  60-80% of amputees experience phantom limb from somatosensory recognition
• Bezzola et al (2012)

  showed increased connections in motor cortex of novice golfers when given golf training at age of 40-60

  suggests the brain can still make connections later in life
• Maguire aims

  To investigate the difference in the brain, especially the hippocampus, in London taxi drivers, and to establish whether differences in hippocampus volume would be observed compared to controls.
• Maguire procedure

  Scanned using an MRI scanner. Scans were analysed and compared with the scans of the control participants.
• Maguire results

  Showed that in the taxi drivers there was an increase in grey matter in only two areas:

  the left and right hippocampi
• Maguire conclusions

  Differences between the hippocampi of London taxi drivers compared to a control group of non taxi drivers. Professional dependence on navigational skills is associated with a redistribution of grey matter in the hippocampus.
• Maguire ethical guidelines

  Guidelines were upheld: no deception, Informed consent given, right to withdraw upheld.

  Guideline broken: MRI is a cramped space and participants (claustrophobic) may have been subjected to harm
• Maguire reliability evaluation

  Internal: Highly controlled experiment so easily repeatable.

  External: Fairly small sample size but shows consistency within results. MRI scans are expensive so 16 is not a bad number.
• Maguire Internal validity

  Scientific measure so no demand characteristics.

  Education, previous jobs and hobbies not considered in control group - could affect hippocampus.
• Maguire Ecological validity

  MRI scanner not something that would happen every day, but this does not change the hippocampal volume.
• Maguire Population validity

  Only males used and only right handed.

  Cannot generalise to females or left handed people.
• Maguire Ethnocentrism

  Is ethnocentric as only taxi drivers from London used.

  Not ethnocentric because brain structure is a species specific behaviour.
• Link to biological area- Maguire

  Investigating neuroplasticity, specifically demonstrating the plasticity of the hippocampi in London taxi drivers.

  Used MRI scanner which gives biological data, in particular measuring the grey matter volume in the hippocampi of the participants
• Link to key theme of brain plasticity - Maguire

  Demonstrated that the fully developed adult human brain could change and adapt to environmental demands.

  Showed brain plasticity in the hippocampus of London taxi drivers with the hippocampi reducing in volume in the anterior hippocampus and increasing in volume in the posterior hippocampus as time spent as a taxi driver.
• Neuronal Unmasking

  "dormant" synapses are activated to compensate for damaged brain areas
•  Taijiri et al.

  found that stem cells provided to rats after brain trauma showed a clear development of neuron-like cells in the area of injury, which shows the brain can create new connections using neurons manufactured by stem cells
• Elbert et al.

  the capacity for neural reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains. suggests that individual differences affect brain recovery
• Schneider et al.

  people with 16+ years of education were more likely to recover from a brain injury than those with <12 years of education, so education makes functional recovery more likely