Plasicity

Plasticity AO1

• The brain’s ability to adapt & change both functionally and physically as a result of new experiences & learning

• During infancy, the brain experiences rapid growth in synaptic connections, peaking at approx 15,00 by age 2-3, almost twice the amount in an adult brain, meaning plasticity is very high

• As we age, rarely used connections are deleted & frequently used connections are strengthened (synaptic pruning)

• Plasticity can be negative eg through prolonged drug use & dementia 

Maguire aim AO1

To investigate if the brain changes in response to environmental demands through studying the structures of london taxi drivers’ brains 

Maguire method AO1

• Took MRI scans of 16 male london taxi drivers brains & compared the structural results to a control group of 50 males who weren’t taxi drivers

Maguire findings AO1

• Taxi drivers had a significant increase in the volume of grey matter in their posterior hippocampus compared to the control group

• Found a positive correlation between the length of time spent as a taxi driver and the volume of the posterior hippocampus — the longer they’d been driving, the larger this area was

Maguire conclusion AO1

• New experiences (eg driving taxis/spatial navigation) can change the brain’s structure (enlarged hippocampus), suggesting the brain isn’t fixed & can adapt 

Functional recovery AO1

• The theory that following brain damage, unaffected areas of the brain can adapt & compensate for damaged areas 

• Young, healthy females have better plasticity 

What are the 3 ways functional recovery occurs? AO1

• Axon sprouting

• Reformation of blood vessels

• Increased brain stimulation

Plasticity strengths AO3

• P - research support (brain plasticity)

• E - Kuhn conducted an experiment where a group of participants played video games for around 30 minutes a day over a two-month period, while a control group played no video games. MRI scans taken before and after the study found increased grey matter volume in areas of the brain associated with spatial navigation & strategic planning, performance, including the hippocampus and prefrontal cortex.

• T - supports brain plasticity by showing that the brain can physically adapt in response to new experiences and learning, therefore increasing the theory’s validity. The use of objective scientific methods such as MRI scanning increases the validity of the findings because the changes in brain structure were directly measured rather than relying on self-report data.

• P - case study support (functional recovery)

• E - E.B. was a 14-year-old boy who had undergone a left hemispherectomy at the age of two to remove a tumour. This surgery removed important language centres, including Broca’s and Wernicke’s areas, causing a complete loss of language ability. However, over the following two years, he gradually recovered his language functions despite no longer having a left hemisphere. Researchers concluded that the right hemisphere had reorganised itself and taken over the language functions normally localised in the left hemisphere.

• T - provides strong support for functional recovery because it demonstrates the brain’s ability to adapt and form new neural pathways after damage. Therefore, it increases the validity of the theory, showing that the brain isn’t fixed like lateralisation proposes but is adaptable.

• P - practical applications

• E - led to neurorehabilitation which uses motor therapy & electrical stimulation of the brain to counter motor & cognitive functions deficits following accidents/strokes. For example, constraint-induced movement therapy is where the unaffected limb is restrained, forcing patients to use the affected limb, which stimulates cortical reorganisation in motor areas & leads to regained movement and strength

• T - real-world value as it has helped improve the quality of life for many patients by providing effective rehabilitation programmes and increasing the likelihood of recovering lost functions after brain injury.

Plasticity limitations AO3

• P - individual differences in functional recovery

• E - Elbert et al concluded that the capacity for neural reorganisation is much greater in children than in adults, meaning that neurorehabilitation may be less effective in older brains. This may also explain why adults find change more demanding than young people, due to to plasticity’s decrease with old age. Furthermore, there are gender differences within plasticity as females have much better, meaning the effects of neurorehabilitation may be more effective than for males.

• T - we must consider individual differences when assessing the likelihood of functional recovery after brain injury. This decreases the generalizability of treatments such as neurorehabilitation, suggesting it is not universally effective