Biopsychology: Plasticity and Functional Recovery Flashcards
What is Brain Plasticity?
The brain’s ability to change and adapt (functionally and physically) as a result of experience and new learning.
Researchers used to believe that changes in the brain only took place during infancy and childhood (experience expectant plasticity).
More recent research has demonstrated that the brain continues to create new neural pathways and alter existing ones to adapt to new experiences as a result of learning and life experiences (experience dependent plasticity).
The brain also appears to show evidence of functional recovery, moving functions from a damaged area of the brain after trauma to other areas.
Name 3 forms of brain plasticity
1) Synaptogenesis
2) Neurogenesis
3) Synaptic pruning (or axon pruning)
Describe synaptogenesis
Synaptogenesis - where new synapses are formed. This can occur throughout life but during infancy there’s an explosion of synaptic formation (known as exuberant synaptogenesis).
Describe neurogenesis
Neurogenesis - this refers to when new neurons are grown. In infancy this is responsible for populating the growing brain with neurons, but also occurs in adulthood.
Describe synaptic pruning
Synaptic pruning (or axon pruning) - the process of synapse elimination that typically happens between early childhood and the onset of puberty. However, this has also been shown to occur to a lesser extent in adulthood.
Describe Experience Expectant Plasticity: Infancy
During infancy, the brain experiences rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 by the age of 2-3 years old (this is synaptogenesis).
This equates to twice as many as there are in the adult brain!
As we age, rarely used connections are deleted and frequently used connections are strengthened (called synaptic pruning).
Describe Experience Dependent Plasticity:(Kuhn)
Kuhn et al (2014) illustrated the potential benefits of playing Super Mario for 2 months (at least 30 mins per day).
They found significant increases in neural connections in certain areas of the brain (e.g. the hippocampus, the prefrontal cortex and the cerebellum) responsible for key behaviours such as working memory, planning and motor performance.
This gives support for synaptogenesis because more grey matter is developing in these areas to deal with the increase in function.
Describe Experience Dependent Plasticity: Computer Gaming
Hippocampus
Changes seen here are likely to reflect navigational learning in the game.
Cerebellum
The increase here is likely to be due to the visual-motor learning in order to play the game.
Prefrontal Cortex
This area is involved in many cognitive processes. At the most basic level just learning when new behaviours are appropriate is likely to be changing this area of the brain.
Describe Experience Dependent Plasticity: Taxi Driving
Maguire et al. (2000) studied the brains of London taxi drivers using an MRI and found significantly more grey matter in the posterior hippocampus than in the matched control group (non-taxi drivers).
This part of the brain is associated with the development of spatial and navigational skills. The longer they had been doing the job the more pronounced was the structural difference (a positive correlation).
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.
Describe Experience Dependent Plasticity: Astronauts
Koppelmans et al. (2016) studied the effect of no gravity in space and how this affects the brain.
27 astronauts were brain scanned before a space mission, then again upon their return.
Between 2 weeks – 6 months in space…
Cerebellum shrunk (involved in coordination) = this effect was positively correlated with time in space
However, the motor and somatosensory regions were swollen
Describe what is meant by functional recovery
Following physical injury or other forms of trauma such as…
Infection (e.g. meningitis)
The experience of a stroke
Individuals may experience loss of brain function including paralysis, aphasia (problems with language), memory loss (amnesia) or difficulties in perception.
In these cases 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.
Neuroscientists suggest that this can happen quickly after trauma (spontaneous recovery) and then slows down after several weeks or months.
A number of structural and functional changes allow the brain to adapt following brain trauma.
These include:
Neural regeneration
Neuronal unmasking
Neural reorganisation
Describe neural regeneration
This is also known as axon sprouting and occurs when new nerve endings grow and connect with undamaged areas.
This can compensate for damaged areas and enable the recovery of previously lost functioning.
This can be seen as a type of SYNAPTOGENESIS.
Describe neural unmasking
This occurs when ‘dormant synapses’ in the brain (which exist anatomically but are blocked from functioning) are opened and become functional.
This can occur when a surrounding brain area becomes damaged as the rate of input to these dormant synapses would increase opening connections to regions of the brain that are not normally activated and allowing the gradual development of new structures.
This can be seen as a type of SYNAPTOGENESIS / NEUROGENESIS.
Describe neural reorganisation
This occurs when the brain transfers functions from the damaged area to undamaged sections of the brain. For example, if Broca’s area in the left hemisphere was damaged then an area on the right hemisphere might take over.
In extreme cases (and with intensive therapy) whole areas of the brain can take over the functions of damaged sections.
Danelli (2013) investigated a case of a boy who had most of his left hemisphere removed aged 2 ½ to remove a tumour. With intensive therapy, his right hemisphere was able to take over almost all of the functioning (language, speech etc) that would normally have been done by the left.
