Biopsychology: Plasticity & Functional recovery Flashcards
What is meant by brain plasticity & how does the brain do this?
The brain’s ability to change and adapt because of experience.
The brain continues to create new neural pathways after alter existing ones in response to changing experiences.
Who did research into plasticity?
Maguire et al
What was the AIM of Maguire’s study?
AIM:
- To examine weather structural changes could be detected in the brain of people with extensive experience of spatial navigation
What was the METHOD in Maguire’s study?
METHOD:
- structural MRI scans
- 16 right-handed male London taxi drivers
- all had been driving for more than 1.5yrs
- scans of 50 healthy right-handed males who did NOT drive taxis were included for comparison (CONTROL GROUP)
- mean age did not differ between two groups
What was the RESULTS from Maguire’s study?
RESULTS:
- Increased grey matter found in brains of taxi drivers compared to CONTROL GROUP in two brain regions (R+L hippocampi)
- Increased volume was found in right posterior hippocampus - Changes with navigation experience
- A correlation was found between the amount of time spent as a taxi driver and volume in right posterior hippocampus
(Larger amount of time spent as a Taxi driver = larger volume in right posterior hippocampus)
What was the CONCLUSION of Maguire’s study?
CONCLUSION:
- results provide evidence for structural differences between the hippocampi of London taxi drivers and control participants
- suggesting that extensive practice with spatial navigation affects the hippocampus
Strengths of Maguire’s study
- study used a highly controlled clinical method for obtaining objective data (MRI scans)
- data can be easily compared & analysed
- study used a researcher who was blind to the conditions to count the pixels of the MRI images INCREASED INTERNAL VALIDITY
Limitations of Maguire’s study
- Correlation cannot show cause & effect
- Impossible to know whether the taxi drivers already had naturally high levels of hippocampal grey matter
- Results are only generalisable to male, right-handed London taxi drivers
What is meant by functional brain recovery
Form of plasticity. Following damage through trauma, the brain’s ability to redistribute or transfer functions usually performed by a damaged area(s) to other, undamaged area(s).
What do neuroscientists believe about this process?
It occur quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. Individuals may then require rehabilitative therapy to further their recovery.
What happens in the brain during recovery? And what is then activated?
The brain is able to rewire 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 activated to enable functioning to continue
What structural changes occur in the brain during recovery?
Axonal sprouting:
- growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways
Denervation supersensitivity:
- axons that do a similar job become aroused to a higher level to compensate for the ones that are lost. However, it can have the negative consequence of oversensitivity to messages such as pain
Recruitment of homologous (similar) areas on opposite side of brain:
- means that specific tasks can still be performed
(e.g. If Broca’s area was damaged on left side of brain = right sided equivalent would carry out its functions)
- after a period of time, functionality may then shift back to the left side
EVALUATION: 1 strength & 1 limitation of Brain plasticity
Limitation: Negative plasticity
- plasticity may have negative consequences
- e.g. 60-80% of amputees known to develop phantom limb syndrome
- which is the continued experience of sensations in the missing limb which is painful and unpleasant
- due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss
- suggests that brain’s capacity to adapt to damage is not always beneficial
EVALUATION: 1 strength & 1 limitation of functional recovery
Strength: Real world application
- Understanding processes involved in plasticity has contributed to the field of neurohabilitation
- e.g. constraint-induced movement therapy is used with stroke patients where they repeatedly practise using the affected part of their body while the unaffected body part (e.g. other arm) is restrained
- shows that research into functional recovery is useful as it helps medical professionals
Limitation: Cognitive reserve
- level of education may influence recovery rates
- Schneider et al: more time spent in education (indicator of cognitive reserve) = greater chances of disability-free recovery
- 40% with DFR= more than 16 yrs in education
- 10% with DFR= less than 12 yrs in education
- implies that people with brain damage who have insufficient DFR are less likely to achieve a full recovery
