BP - Brain Plasticity and Functional Recovery Flashcards
What did scientists previously think about the brain 20 years ago compared to modern theory?
They thought our brains stopped developing once we reached adulthood - however, due to functional brain imaging, we now know that learning causes the brain to constantly change and continues to strengthen connections
What happens to synapses?
Between the age of 0-3, we develop around 6x more synapses than we had (2,500 -> 15,000)
What happens between age 3 and adulthood?
They shrink up when no longer needed in synaptic pruning; more and stronger dendrites are used to strengthen STM and synapses are reinforced and change.
- The synapses are able to forge and be created with the LTM to reinforce information
- Synaptic pruning - the less you use a connection, the more likely you will lose it
What is brain plasticity?
- The capability of living things to mold themselves to new conditions
- Describes the brain’s tendency to change and adapt (functionally and structurally) as a result of new experiences, new learning or training
- Also known as neuroplasticity and cortical remapping
- Recent research has suggested that plasticity occurs throughout the lifespan; existing neural connections can change or new neural connections can be formed as a result of learning and experience
- However, functional plasticity tends to reduce with age and so the brain has a greater prosperity for re-organisation in childhood as it consistently adapts to new experiences and learning
- During infancy, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at an approximately 15,000 at 2-3 years old
- As we age, rarely used connections are deleted and frequently used connections are strengthened - synaptic pruning
Activities that promote plasticity
- Meditation
- Learning languages
- Driving
- Learning new skills
- Reading
- Video games / crosswords etc
Functional Recovery after trauma
- A type of plasticity
- Following damage through trauma, functional recovery is the brain’s ability to redistribute or transfer function usually performed by damaged areas to other, undamaged areas
- This functionally changes the brain (sometimes structurally) as a result of a traumatic experience
- Older people may still be able to build new connections
- Spontaneous recovery may initially occur, before slowing down, which may require rehabilitation
- Often known as neural reorganisation where functions are redistributed or transferred to undamaged areas
- Plasticity allows the brain to cope better with ‘indirect’ affects of brain damage and recovery following trauma may be enhanced by brain stimulation of the opposite hemisphere to the trauma, physiotherapy etc
Factors affecting brain recovery after trauma - Perserverance
- Functional recovery is dependent on this - sometimes a function may appear to be lost, but that could be because the individual affected may not be trying and takes the view they cannot recover
- Animal studies have shown that when they have a limb that has lost its sensory input (deafferented) they try to avoid using it; however, if another limb is damaged, they have no other option but to use the limb without sensory input
- The motor nerves are still connected to the limb, but the sensory nerve connections are damaged and so the monkey feels as though it doesn’t work - perception therefore affects recovery (Taub and Berman 1968)
Factors affecting brain recovery - Physical exhaustion, stress and alcohol consumption
- When function is recovered it is important to remember that often the function is used with considerable effort ad although the person can do a task, they are often fatigued by the effort
- Other factors like stress and alcohol can affect the ability to use any regained function (Fleet and Heilman 1986)
Factors affecting brain recovery - Age
- There is brain deterioration with old age and this affects the extent and speed of recovery
- Marquez et al study (2008) - found that patients above 40 years old regained less function after treatment than younger patients and were more likely to decline in function 5 years after trauma and treatment
- Contemporary case study Danelli et al (2013) - illustrates the extent a young brain can regain function after severe damage
Factor affecting brain recovery - Gender
- Some research suggests that women recover better from brain trauma than men as their function is not as lateralized
- Ratcliffe et al (2007) examined 325 patients with brain trauma for their level of response for cognitive skills to rehabilitation
- The patients were 16-45 years old at injury, and all received rehab at a care facility, followed by a complete follow-up a year later
- None had prior learning problems
- When assessed for cognitive skills, women performed consistently and significantly better than men on tests of attention and working memory and language whereas men outperformed females in visual analytical skills
- The results overall suggest more effective recovery for women, however, results did not control for performance pre-injury, so this could influence results
- Research is however mixed so clear conclusions cannot be drawn
Evidence of plasticity - Taxi drivers
Procedure:
- Mcguire et al (2000) studied the brains of London taxi drivers, and as a part of their training they have to take a complex test called ‘the Knowledge’ which assess their recall of the city streets and possible routes
Results:
- There was significantly more evidence of grey matter in the posterior hippocampus of the taxi drivers in comparison to match controls
- This part of the brain is associated with spatial awareness development and navigational skills in humans and animals
- The longer they had been in the job, the more pronounced the structural difference (positive)
- This is strong evidence for plasticity - detailed, controlled study
Evidence of plasticity - examples 2 and 3
Procedure 1:
- Draganski et al (2006) imaged the brains of medical students 3 months before and after their final exams
Results 1:
- There were changes to the posterior hippocampus and parietal cortex, presumably because of the exam
- Weak evidence - too many unaccounted factors, not enough detail, only casual links of the cortex and learning
Procedure 2:
- Mechelli et al (2004) compared bilingual brains to matched monolingual controls
Results 2:
- They found a larger parietal cortex in the brains of bilingual people
- Weak - again, lack of detail and control of factors such as background and only links learning to this cortex
Evidence of plasticity - Video gamers
Procedure:
- Kuhn et al (2014) compared a control group with a video game training programme group that were trained for two months for at least 30 minutes per day on the game Super Mario
Results:
- They found a significant increase in grey matter in various brain areas, including the cortex, hippocampus and cerebellum - these increases were not evident in a control group
- It was concluded that the video game training had resulted in new synaptic connections in brain areas of spatial navigation, strategic planning, working memory and motor performance, all of which are skills needed to play the game well
- Strong evidence for plasticity, as function was able to be improved in used areas (more they did it, the stronger the area’s function)
Evidence of plasticity - meditation
Procedure:
- Davidson et al (2004) 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
Results:
- The electrodes picked up much greater activation of gamma waves (important because they coordinate neuron activity) in the monks - the students showed only a slight increase in gamma wave activity while mediating
- It was concluded that meditation not only changes the way the brain works in the short term, but may also produce permanent changes, based on the fact the monks had much more gamma wave activity than the control group even before they started meditating
- Strong evidence - detailed, controlled, uses comparison from before and after
Evaluation of plasticity - positive supporting evidence
- The evidence of plasticity can be all used to support plasticity - these studies all suggest that the brain changes and adapts functionally and structurally as a result of experience, supporting the theory of plasticity
- Bezzola et al demonstrated how 40 hours of golf training produced changes in the neural representation of movement in participants aged 40-60 - using fMRI, researchers were able to observe reduced motor cortex activity in the novice golfers compared to control groups
- This suggests more efficient neural representations after training
- This suggests that neural plasticity continues throughout the lifespan
