Plasticity

• The brain is plastic - synaptic connection form and are pruned. During infancy, the brain experiences a rapid growth in synaptic connections, peaking at about 15,000 at age 2-3 (Gopnik). As we age, rarely used connections are deleted and frequently used connections are strengthened -synaptic pruning. It was once thought these changes were limited to childhood. Recent studies suggest neural connections can change or be formed at any time, due to learning and experience.
• Maguire found significantly more volume of grey matter in the posterior hippocampus in London taxi drivers than in the matched control group. This part of the brain is linked with the development of spatial and navigational skills. As part of their training, London cabbies take a complex test called ‘the knowledge’ to assess their recall of city streets and possible routes. This learning experience appears to alter the structure of the taxi drivers brains. The longer they had been in the job, the more pronounced the structural difference.
• Dragonski imagines the brains of medical students three months before and after their final exams. Learning induced changes were seen in the posterior hippocampus and the parietal cortex, presumable as a result of learning for the exam.
• +Possible negative behavioural consequences. The brain's adaptation to prolonged drug use leads to poorer cognitive functioning in later life, as well as an increased risk of dementia - Medina. 60-80% of amputees have phantom limb syndrome where they experience sensations in missing limb due to changes in the somatosensory cortex. This suggests that the brain's ability to adapt to damage isn’t always beneficial and may lead to physical and psychological problems.
• +May not decline sharply with age - Bezzola demonstrated how 40 hours of golf training produced changes in the neural representations in participants aged 40-60. Using fMRI, motor cortex activity in the novice golfers reduced compared to a control group, suggesting greater efficiency after training. This shows that neural plasticity can continue throughout the lifespan.
• +Seasonal brain changes- Tramotin and Brenowitz found seasonal plasticity occurs in response to environmental changes. The suprachiasmatic nucleus shrinks in spring and expands in autumn. However, much of the work on seasonal plasticity has been done on animals (songbirds). Human behaviour may be controlled differently therefore

  suggesting that animal research can't be generalised to humans.