plasticity

Question 1

what is plasticity?

Answer 1

the brain’s tendency to change and adapt due to experience and learning involving the growth of new connections

Question 2

describe the brain’s plasticity throughout life

Answer 2

• during infancy, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at about 15,000 per neuron at 2-3 years (gopnik et al. 1999)
• this is about twice as many there are in the adult brain
• people once thought that the adult brain was not capable of change but we now understand that synpatic pruning enables lifelong plasticity where new neural connections are formed in response to new demands on the brain

Question 3

what is synaptic pruning?

Answer 3

the process by which rarely-used connections are deleted and frequently-used connections are strengthened as we age

Question 4

research into plasticity: maguire et al. (2000)

Answer 4

• studied that brains of london taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group
• the longer the taxi drivers had been in the job, the more pronounced the structural difference (a positive correlation)

Question 5

what could explain maguire et al.’s findings?

Answer 5

• posterior hippocampus area is associated with the development of spatial and navigational skills
• as part of their training, london taxi drivers must take a complex test called ‘the knowledge’ which assesses their recall of the city streets and possible routes
• maguire et al. found that this learning experience alters the structure of the taxi drivers’ brains

Question 6

research into plasticity: draganski et al. (2006)

Answer 6

• imaged brains of medical students 3 months before and after their final exams
• learning-induced changes occurred in the posterior hippocampus and the parietal cortex, presumably as a result of the learning

Question 7

evaluation: plasticity may have negative behavioural consequences (drug use)

Answer 7

• medina et al. (2007) showed that the brain’s adaptation to prolonged drug use leads to poorer cognitive functioning in later life and an increased risk of dementia
• the brain’s ability to adapt is not always beneficial

Question 8

evaluation: plasticity may have negative behavioural consequences (phantom limb syndrome)

Answer 8

• 60-80% of amputees develop this
• continued experience of sensations in the missing limb as if it were still there
• these sensations are usually unpleasant and painful
• thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss (ramachandran and hirstein 1998)

Question 9

evaluation: brain plasticity may be a life-long ability

Answer 9

• in general, plasticity reduces with age
• however, bezzola et al. (2012) demonstrated how 40 hours of golf training produced changes in the neural representations of movements in paritcipants aged 40-60
• using fMRI, the researchers observed increased motor cortex activity in the novice golfers compared to a control group, suggesting more efficient neural representations after training
• this shows that neural plasticity can continue through the lifespan

Question 10

evaluation: seasonal brain changes

Answer 10

• research suggests that there many be seasonal plasticity in the brain in response to environmental changes
• eg. there is evidence that the suprachiasmatic nucleus (SCN), which regulates the sleep/wake cycle) shrinks in all animals during spring and expands throughout autumn (tramontin and brenowitz 2000)

Question 11

evaluation: against seasonal brain changes

Answer 11

• much of the work on seasonal plasticity has been done on animals, notably songbirds
• human behaviour may be controlled differently
• issues of generalisability etc.

Question 12

evaluation: meditation and mindfulness evidence (lazar et al. 2005)

Answer 12

• using MRI scans, demonstrated how experienced meditators had a thicker cortex than non-meditators, particularly in areas related to attention and sensory processing
• meditation and mindfulness may alter the structure and function of the brain

Question 13

evaluation: meditation and mindfulness evidence (holzel et al. 2011)

Answer 13

• individuals who took part in an 8-week mindfulness-based stress reduction course showed an increase in grey matter in the left hippocampus
• this part of the brain is strongly associated with learning and memory

Question 14

evaluation: meditation and mindfulness evidence (tang et al. 2012)

Answer 14

• four weeks of meditation resulted in an increase in white matter in the anterior cingulate cortex
• this part of the brain contributes to self-regulation and control, a key aspect of meditational practice