Plasticity and Functional Recovery in the Brain Flashcards
What is Plasticity?
The brain’s ability to change + adapt as a result of experience + new learning
=> as a child grows, brain experiences rapid increase in synaptic connections peaking at around 15000 (Gopnik et al, 1999)
Synaptic Pruning
Connections no longer used are removed + frequently used ones are strengthened
- Occurs ages 2-10
- Previously thought to not happen in adults but gives lifelong plasticity
Research Support for Plasticity in London Taxi Drivers - Maguire et al, 2000
- Studied their brains using MRI scans
- Significantly greater vol. of grey matter in posterior hippocampus than matched control group
- Brain area associated w/ spatial + navigation skills likely changed due to completing the Knowledge to assess recall of city routes during training
- The longer they had the job, the more pronounced the structural difference
Plasticity Supported by Research on Learning
- Dragonski et al (2006)
- imaged brains of medical students 3 months before + after final exams
- changes in posterior hippocampus + parietal cortex
Mechelli et al
- found a larger parietal cortex in the brains of those who are bilingual than monolingual brains
(S) Plasticity may not decline w/ age - Bezzola et al (2012)
- Demonstrated how 40 hours of golf training produced changes in neural representation in those aged 40-60 yrs
- Using fMRI, motor cortex activity in golfers increased compared to control
Shows => neural plasticity can change throughout life
(L) of Plasticity - Possible negative behavioural consequences - Medina et al (2007)
- Brain’s adaptation to prolonged drug use lead to poorer cog. functioning as well as increased dementia risk
- 60-80% of amputees have phantom limb syndrome due to changes in somatosensory cortex
Suggests => brain’s ability to adapt to damage is not always beneficial + may lead to physical and psychological issues
AO3 Extra for Plasticity : Seasonal Brain Changes
Occurs in response to environmental changes - Tramontin + Brenowitz
=> The suprachiasmatic nucleus (SCN) shrinks in spring and expands in autumn
=> Much work on this is done on animals e.g. kitten with eye sewed shut had visual cortex for shut eye process info from open eye
Suggests => loss of functiom leads to compensary activity in brain but these findings may not generalise to humans
What is Functional Recovery?
- Following trauma to brain - brain redirects/transfers function to undamaged areas
- Secondary neural pathways are unmasked
- Brain reorganises by forming new synaptic connections close to area of damage
- Spontaneous recovery occurs quickly after trauma
- Rehabiliative therapy is needed as this slows down after weeks or months
Structural change to brain - Axonal Sprouting
New nerve endings grow to connect w/ other undamaged cells to form new neural pathways
Structural change to brain - Denervation Supersensitivity
- Surrounding axons that process similar transmitters become more aroused (‘supersensitive’) to compensate for ones lost (‘denerved’)
Structural change to brain - Recruitment of Homologous Areas in the Brain
Nearby or opposite side of brain takes over specific tasks
e.g. right side equivalent of Broca’s area take over language production following damage
(S) Real World Application of Functional Recovery
Understanding plasticity has led to neurorehabilitation
Understanding axonal growth encourages new therapies
e.g. Constraint-induced movement therapy involves massed practice with affect arm while unaffected is restrained - won’t take over task
Suggests => research into functional recovery helps professionals know when interventions can be made
(L) Functional recovery may be related to cognitive reserve - Schneider et al (2014)
Cog. reserve - the extent brain can sustain damage
=> been shown those with higher literacy rate, educational level and IQ have higher CR
- Found 40% of patients who achieved disability free recovery had >16yrs of education compared to 10% of patients who had <12yrs
