Brain plasticity:
Plasticity refers to the ability of the brain to change its own structure (synapses,
pathways) and function as a result of various experiences
Processes involved in brain plasticity:
- Synaptogenesis: growth of new synapses
- Neurogenesis: growth of new neurons
- Synaptic pruning: eliminating unwanted or unused synapses
Plasticity as a result of life experience
As people gain new experiences, nerve pathways that are used frequently develop
stronger connections, whereas neurons that are rarely or never used eventually die. By
developing new connections and pruning away weak ones (synaptic pruning), the brain is
able to constantly adapt to a changing environment. However, there is also a natural
decline in cognitive functioning with age that can be attributed to changes in the brain.
The brain becomes less plastic as it ages. Much of the brain’s plasticity is lost after two
years of age, there is significant plasticity up until puberty, and relatively little in adulthood.
Evidence for plasticity in the brain:
Juggling
Boyke et al. (2008) found evidence of brain plasticity in 60-year-olds taught a new skill –
juggling.
They found increases in grey matter (consists of neuronal cell bodies and their dendrites)
in the visual cortex, although when practising stopped, these changes were reversed.
Video Game Playing
Kuhn et al. (2014) compared a control group with a video game training group that was
trained for 2 months for at least 30 mins per day in the game Super Mario.
They found a significant increase in grey matter (neurons) in various brain areas including
the cortex, hippocampus and cerebellum. This increase was not evident in the control
group that did not play Super Mario.
, The researchers concluded that video game training had resulted in new synaptic
connections in brain areas involved in spatial navigation, strategic planning, working
memory and motor performance – skills that were important in playing the game.
Functional recovery:
This is a form of plasticity. Following damage through trauma, this refers to the brain’s
ability to redistribute or transfer functions usually performed by a damaged area(s) to
other, undamaged areas.
(Brain trauma = stroke, physical trauma, viral/bacterial infections)
Following physical injury, or other forms of trauma such as the experience of a stroke,
unaffected areas of the brain are often able to adapt and compensate for those areas that
are damaged.
The functional recovery that may occur in the brain after trauma is an example of neural
plasticity.
Healthy brain areas may take over the functions of those areas that are damaged,
destroyed or even missing (neural reorganisation). Neuroscientists suggest that this
process can occur quickly after trauma (spontaneous recovery) and then slow down
after several weeks or months. At this point, the individual may require rehabilitative
therapy to further their recovery.
Mechanisms for recovery/factors affecting recovery:
Functional This is brought about by intensive rehabilitation. The brain learns to
compensation compensate for function. The brain can be taught to learn how to use
the working faculties and functions to compensate for the ones that are
lost forever.
Age at which There is a deterioration of the brain in old age, and this therefore affects
damage occurs the extent and speed of recovery. Teuber (1975) studied soldiers with
brain damage. He found that recovery from movement and visual
problems over 20 years was age dependent: 60% of those under 20
showed significant improvement, while only around 20% of those over
26 showed similar recovery.
Axonal sprouting When an axon is damaged, its connection with a neighbouring neuron
is lost. In some cases, other axons that already connect with that
neuron will sprout extra connections to the neuron, replacing the ones
that have been destroyed.
Rehabilitation The practice of a skill affected by brain damage (as would happen
during physiotherapy and speech therapy) alters brain reorganisation