Two Key Studies of Neuroplasticity: Maguire (2000) & Luby (2013) (SL IB Psychology)

Aim: To investigate a neuroplasticity in London black cab taxi drivers as a result of experience in spatial navigation

Participants: 16 healthy, right-handed male London black cab taxi drivers who had passed ‘The Knowledge’, a test of spatial navigation, aged 32-62 years with a mean age of 44 years. They had all been taxi drivers for at least 18 months, with the highest number of years as a taxi driver at 42 years

Procedure: The participants were placed in an MRI scanner and their brains were scanned. The MRI measured the volume of grey matter in the hippocampus of each participant, and this was then compared to pre-existing scans of 50 healthy, right-handed males (the control group). Grey matter was measured using voxel-based morphemetry (VBM) which focuses on the density of grey matter and pixel counting

Results: The posterior hippocampi of the taxi drivers showed a greater volume of grey matter than that of the controls, who had increased grey matter in their anterior hippocampi compared to the taxi drivers. Maguire also carried out a correlational analysis which showed a positive correlation between volume of posterior hippocampal grey matter and length of time spent as a taxi driver

Conclusion: The posterior hippocampus may be linked to spatial navigation skills

Evaluation of Maguire (2000)

Strengths

• The study used a highly controlled clinical method of obtaining objective data which could then be easily compared and analysed
• Understanding neuroplasticity can help aid the recovery of people who have suffered brain damage

Limitations

• A correlation cannot show cause-and-effect so it is impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter
• The results are only generalisable to male, right-handed London taxi drivers so the nature of neuroplasticity in women is not known

Key terms:

• Spatial navigation  
• Posterior hippocampus   
• Voxel-based morphometry  

Aim: To investigate whether poverty experienced in childhood is shown in delayed brain development and the extent to which mediating factors may influence early deprivation.

Participants: Children who were already enrolled on a 10-year longitudinal study of Preschool Depression: 145 right-handed children from the USA. The children were categorised as living in poverty.

Procedure: The children had undergone regular testing: once a year (over 3-6 years) which consisted of a series of tests aimed to measure their cognitive, emotional and social skills. The researchers also collected data on how close the children were to their caregivers as well as incidences of any negative and stressful events in their lives. Each child then had two MRI scans in which the whole brain was scanned (session 1) or just the hippocampus and the amygdala (session 2).

Results: Both the hippocampus and the amygdala showed less white and grey matter in the MRI scans. However, if the child had experienced positive care from adults there was a less negative effect on the hippocampus. Difficult and stressful life events only affected the left hippocampus.

Conclusion: Poverty does appear to have a negative effect on brain development in childhood, but this can be reduced by the quality of caregiving the child experiences.

Evaluation of Luby et al. (2013)

   Strengths

• • The researchers were able to check the behavioural, cognitive, and social measures against the MRI results which increases the internal validity of the study
  • The study’s longitudinal design means that real changes and comparisons across time could be made

   Limitations

• • Attempting to measure complex variables (e.g. nature of caregiving, social skills) is difficult as these variables are not exact and may be prone to researchers interpreting them in subjective ways
  • The sample is difficult to generalise from as it only represents pre-school children living in poverty who exhibit symptoms of depression so it cannot explain how poverty may affect non-depressed children

Key terms:

• Hippocampus  
• Amygdala  
• Mediating factors