A2 Biopsychology - Plasticity

Question 1

What happens to plasticity in infancy vs as we age?

Answer 1

At infancy, the brain experiences a rapid growth in the number of synaptic connections. Each neuron has up to 15000 connections to other neurons (over twice as many as in adulthood)

As we age, the rarely used connections are weakened or deleted whilst the frequently used ones are strengthened (called synaptic pruning)

Question 2

Give the original view vs the current view of brain plasticity.

Answer 2

Original view: brain could only change in childhood

Current view: although plasticity does reduce with age, existing neural connections can be changed at any age and new ones can be formed from learning and experience.

Question 3

Give two supporting studies for plasticity.

Answer 3

Maguire (2000) found significantly more grey matter in the posterior hippocampus of London cab drivers than a non cab driver control group, and found that grey matter increases with experience. Posterior hippocampus is linked to space and memory.

Draganski (2006) analysed brains of medical students 3 months before an exam and straight afterwards and also found significant changes in grey matter of posterior hippocampus.

Question 4

What is involved in functional recovery after trauma?

Answer 4

The brain can repair itself after damage from illness or injury (trauma), but this spontaneous recovery slows down over time, so rehabilitative therapy may be required later.

The processes involved are:

1) Axonal sprouting: new pathways form as new nerve endings grow
2) Blood vessel reformation
3) Recruitment of homologous areas: similar areas on the opposite side of the brain may adapt and take over the functions lost. Recruitment is done via the new nerve endings.

Question 5

Evaluate plasticity and functional recovery after trauma.

Answer 5

(+) Led to the development of neurorehabilitative therapies eg constraint-induced therapy (where able body parts are restricted to force affected parts to recover), transcranial magnetic therapy and movement therapy.
(+) Hubel and Weasel (1963) sewed kittens’ left eyes shut and found RH part of brain had started helping LH part as RH had stopped receiving information.
(-) Plasticity reduces with age
(+) although a study showed that 40-60yr old golfers could learn new skills which led to permanent brain changes
(-) Ramachandrandt and Hirstein (1998) found that plasticity led to phantom limb pains in amputees
(-) Persistent drug or alcohol misuse can reduce plasticity which inhibits recovery after trauma.
(-) Localisation of function