Plasticity and Functional recovery of the brain Flashcards
What is brain plasticity?
Refers to the brain’s ability to modify its own structure and function as a result of experience and new learning
What is functional recovery?
A form of plasticity. Refers to the recovery of abilities and mental processes that have been compromised as a result of brain injury or disease.
What is synaptic pruning?
With age rarely used synaptic connections in the brain are deleted and frequently used connections strengthened.
What are 3 structural changes the brain undergoes to help it recover after trauma?
- Axonal sprouting: new nerve endings grow and connect with other undamaged nerve cells to form new neural pathways
- Reformation of blood vessels
- Recruitment of homologous (similar) areas on the opposite hemisphere
who did research into plasticity of the brain?
Eleanor Maguire et al (2000)
Davidson et al (2004)
Describe Eleanor Maguire et al’s (200) study into brain plasticity
Eleanor Maguire et al (2000):
- Studied the brains of London taxi drivers .
- As part of their training London Cabbies must take a complex test called ‘the knowledge’, which assesses their recall of the city streets and possible routes.
- Maguire scanned their brains using an MRI and found significantly more grey matter in the posterior hippocampus than in the matched control group. This part of the brain is associated with the development of spatial and navigational skills in humans and other animals.
- It was also found the longer they had been doing the job the more pronounced was the structural difference (a positive correlation).
Describe Davidson et al’s (2004) study into brain plasticity
- Compared 8 practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience.
- Both groups fitted with electrical sensors and asked to meditate for short period.
- There was much greater activation of gamma waves in the monks compared to the students.
- The monks had far more gamma wave activity than the control group even before they started meditating, suggesting that meditation may produce permanent changes in the brain.
What is functional recovery after trauma?
- Following physical injury or other forms of trauma such as infection or the experience of a stroke, unaffected areas are sometimes able to adapt or compensate for those areas that are damaged. The functional recovery that occurs in these cases is an example of neural plasticity. Neuro scientists suggest that this can happen quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. Therapy may then be needed.
- What happens in the brain during recovery?
The brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage. Secondary neural pathways that would not typically be used to carry out certain functions are ‘unmasked’ to enable functioning to continue. This process is supported by a number of structural changes.
1.Axonal sprouting: new nerve endings grow and connect with other undamaged nerve cells to form new neural pathways.
2. Reformation of blood vessels.
3. Recruitment of homologous (similar) areas on the opposite hemisphere to do specific tasks. E.g if Broca’s area was damaged then the right-sided equivalent would carry out its function. After time, functionality may then shift back to the left. EVIDENCE= patient J.W. (looked at last lesson).
What are the two strengths of plasticity?
Research support from animal studies for neural plasticity- Kempermann et al. (1998)- found evidence of an increased number of new neurons in the brains of rats housed in complex environments compared to rats housed in laboratory cages. The rats housed in the complex environment= an increase in neurons in the hippocampus (associated with the ability to navigate from one location to another).
Research support from humans for neural plasticity- Maguire et al. (2000)= London cabbies and Davidson et al. (2004)= Tibetan monks
-Both used a control group- allows us to conclude that there is a significant difference
-Use of scientific, objective measurements (MRI and electrodes fitted to brain)
-Both attempted to study a real world phenomena- high ecological validity
What are the two limitations of plasticity?
Negative plasticity- The brain’s ability to rewire itself can sometimes have maladaptive behavioural consequences.
It was found that prolonged use of marijuana resulted in poorer cognitive functioning as well as an increased risk of dementia later in life.
Phantom limb syndrome= 60-80% of amputees have been known to develop this. This means they continue to experience sensations in the missing limb as if it were still there. These sensations are usually unpleasant and are thought to be due to the cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss.
Plasticity changes with age- Age is a confounding variable which affects the plasticity of the brain. Functional plasticity tends to reduce with age. According to this view the only option following traumatic brain injury beyond childhood is to develop compensatory behavioural strategies to work around the deficit (such as seeking social support for developing strategies to deal with cognitive deficits).
Counter- Some studies have shown that even abilities commonly thought to be fixed in childhood can still be modified in adults with intense retraining. Researchers showed that 40 hours of golf training in 40-60 year olds produced changes in the neural representation of movement suggests that neural plasticity is evident in all ages and not just young people.
What is the strength of functional recovery?
Support from animal studies for functional recovery- Hubel and Wiesel (1963)- sewed one eye of a kitten shut and analysed the brain’s cortical responses. It was found that the area of the visual cortex associated with the shut eye was not idle (as predicted) but continued to process information from the open eye.
What is the limitation of functional recovery?
Level of education may influence functional recovery- The level of education may influence recovery rates.
Schneider et al. (2014) the more time people with a brain injury had spent in education (taken as an indication of their cognitive reserve) the greater their chances of a disability-free recovery (DFR). 40% of those who achieved DFR had more than 16 years’ education compared to 10% of those who had less than 12 years’ education.
Implies that people with brain damage who have insufficient DFR are less likely to achieve a full recovery.
