plasticity Flashcards
what is brain plasticity
the brain’s ability to modify its own structure and function as a result of experience and new learning
plasticity AO1
during infancy, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 by the age of 2-3 years. This is twice as many as there are in the adult brain.
As we age, rarely used connections are deleted and frequently used connections are strengthened in a process known as cognitive pruning. This shows that the brain is in a continual state of change from growth in early years to change and refinement in adulthood as we learn and experience.
plasticity research
Maguire et al (2000) studied the brains of London taxi drivers using MRI and found significantly more grey matter in the posterior hippocampus than those in the matched control group. This part of the brain is associated with spatial and navigational skills in humans and other animals.
As part of their training, London cabbies must take a complex test called ‘the knowledge’ which assesses their recall of city streets and possible routes. The longer they had been doing the job, the more pronounced was the structural difference.
This shows plasticity because there is a change in the brain of London cabbies from the learning and experience as they have done the job.
strength of Maguire’s research into plasticity (MRI)
the use of MRI allows a scientific and objective measurement to be made which reduces the possibility of researcher bias.
strength of Maguire’s research (control group)
the use of a control group allows us to say that there is a significant difference between taxi drivers and others. (good design)
weakness of Maguire’s research
the difference between the taxi drivers hippocampi might have always been there and this could have led them to do a job where navigational skills were important due to the already existing difference.
Despite this methodological weakness, the results still support plasticity because the longer they had been a cab driver, the greater volume of their posterior hippocampus.
negative plasticity
plasticity can be negative. Prolonged drug use has been shown to result in poorer cognitive functioning as well as an increase in risk of dementia later in life.
60-80% of amputees have been known to develop phantom limb syndrome. These sensations are often unpleasant, painful and thought to be due to the reorganisation of the somatosensory cortex as a result of the limb loss.
Draganski et al. study of plasticity
Draganski et al imaged the brains of medical students three months before and after final exams. Learning-induced changes were seen in the posterior hippocampus as a result of learning for the exam.
Kempermann et al. study
Kempermann et al. investigated whether an enriched environment can alter the number of neurons in the brain. They found evidence of an increased number of neurons in the brains of rats housed in complex environments compares to rats housed in lab cages. In particular, an increased number of neurons in the hippocampus which is associated with spatial and navigational abilities.
Tibetan monks study
Researchers have demonstrated that meditation can change the inner workings of the brain. Davidson et al. compared 8 practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience. Both groups were fitted with electrical sensors and asked to meditate for short periods. The electrodes picked up on much greater activity of gamma waves in the monks. The students showed only a slight increase in gamma wave activity.
Concluded that meditiation not only changes the workings of the brain in the short term but also may produce permanent changes as the monks had greater gamma wave activity even before meditation.
