Biopsych: Brain Plasticity Flashcards
What is brain plasticity?
If a brain is plastic, it means it can adapt and change over time. In infancy the brain experiences growth in the number of synaptic connections it has, peaking at approx 15,000 at 2-3 yo (Gopnick et al 1999). This is 2x more than the adult brain.
What happens to our synaptic connections as we age?
Rarely used connections are deleted and frequently used connections strengthened - known as synaptic pruning.
- was originally thought such changes were restricted to the developing brain, and after a certain period it remains fixed in function and structure, yet research suggests that any time in life, existing neural connections can change, or new connections can be formed as a result of learning and experience.
What did Maguire find about brain plasticity in the brains of local taxi drivers?
Found a lot more volume of grey matter in the posterior hippocampus than in the matched control group.
- this part of the brain is associated with the development of spatial/navigational skills in humans and other animals.
- as part of training, London cabbies need to take ‘the Knowledge’ which assesses their recall of the city. It appears that this spatial learning alters the structure of the taxi drivers.
What did Maguire also find about the posterior hippocampus?
Also found a positive correlation between the size of the posterior hippocampus and time as a taxi driver. Correlations are not causal, but implies the experience of being a taxi driver changes the brain (or at least the hippocampus)
What did Draganski et al find to support brain plasticity?
Imaged the brain of medical students 3 months before and after their final exams. Learning induced changed seemed to occur in the posterior hippocampus and the parietal cortex, presumably as a result of studying for exams.
What did Mechelli et al find that supports brain plasticity?
Found a larger parietal cortex in the brains of people who were bi-lingual compared to matched monolingual controls
What is functional recovery of the brain after trauma?
Following physical injury or trauma, such as stroke, unaffected areas of the brain are able to adapt and compensate for those areas that are damaged.
- this is an example of brain plasticity
- Neuroscientists suggest that this process can occur quickly after trauma and then slow down after several weeks or months. At this point, the individual may need rehabilitative therapy.
What happens to the brain during recovery?
The brain is able to rewrite/reorganise itself by forming new synaptic connections close to the area of damage.
Secondary neural pathways (not typically used to carry out certain functions) are activated to enable functioning to continue, often in the same way as before (Doidge, 2007)
What is axonal sprouting and how is it a structural change?
Growth of new nerve endings which connect with other undamaged nerve cells to form new neural pathways
What’s another structural change?
Reformation of blood vessels
How is recruitment of homologous areas another structural change?
When homologous (similar) area of the brain on the opposite side is used to perform a specific task
- e.g. if Broca’s area was damaged (left side of the brain), the right sided equivalent would carry out its functions
- after a period of time, functionality may then shift back to the left side
What are the practical applications from these brain plasticity theories?
- understanding the processes involved in plasticity has contributed to the field of neurorehabilitation. E.g. understanding when recovery slows down, so that therapy is then required to maintain improvements in functioning.
- techniques may include movement therapy and electrical stimulation of the brain to counter the deficit in motor and/or cognitive functioning following a stroke, for example.
What’s a study to support the idea that brain plasticity can sometimes have maladaptive behavioural consequences (this is not a strength, but supports the notion of brain plasticity)?
Medina et al found that prolonged use of marijuana resulted in in poorer cognitive functioning as well as increased risk of dementia in later life. 60-80% of amputees develop ‘Phantom limb syndrome’ where they continue to experience sensations in the missing limb as if it was still there. These are thoughts to be due to cognitive reorganisation in the somatosensory cortex and is usually very painful (Kamachandran and Hirstein 1998). These are both examples of brains plasticity.
Who found evidence of plasticity and functional recovery was derived from animals?
Huber and Wiesel involved seeing one eye of a kitten shut and analysing the brains cortical responses. Found the area of visual cortex associated with the shut eye was not idle (as had been predicted) but continued to process info form the open eye.
How might educational level influence how well the brain functionally adapts after injury?
Schneider et al found the more time brain injury patients had spent in education, the greater their chances of a disability-free recovery (DFR). Of the patients who achieved a DFR, 40% had more than 16 years in education, whereas 10% had less than 12 years.
