The Brain - Plasticity and Functional Recovery Flashcards
WHAT IS MEANT BY THE TERM BRAIN PLASTICITY?
The brain’s ability to change and adapt as a result of experience.
Research shows that the brain continues to create new neural pathways and
alter existing ones in order to adapt to new experiences as a result of
learning.
There are many different factors known to affect neuronal structure and
function, including life experience, video games and meditation.
Neuroplasticity?
During infancy, the brain experience a rapid growth in the number of
synaptic connections it has, peaking at approximately 15,000 by the
age of 2-3 years old. This equates to twice as many as there are in
the adult brain. As we age rarely used connections are deleted and
frequently used connections are strengthened in a process known as
cognitive pruning.
This shows that the brain is in a continual state of change from
growth in early years to change and refinement in adulthood as we
learn and experience.
Plasticity - Real World Application
In recent years, it’s become clear not only that neural
organization is changed as a result of experience, but
also that there are many different types of experience
that can do this. Areas investigated have included
video games and meditation.
PLASTICITY AS A RESULT OF LIFE EXPERIENCE
The brain constantly adapts to a changing environment; as we gain new experiences, neuronal pathways that are used frequently develop stronger connections whereas those that are rarely or never used eventually die
However there is also a decline in cognitive ability due to age, which
can be attributed to changes in the brain – can this effect be reversed?
Boyke et al. (2008) – found evidence of brain plasticity in 60 year-olds taught a new skill – juggling. They found increases in grey matter in the visual cortex (although when practising stopped this was
reversed)
PLAYING VIDEO GAMES
Playing video games makes many complex cognitive and motor demands
Kuhn et al. (2014) – participants trained for at least 30 mins a day for 2
months on Super Mario. Significant increase in grey matter in several areas
of the brain (this did not happen for a control group). Video game training
resulted in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance.
MEDITATION
Davidson et al. (2004) – 8 Tibetan monks and 10 volunteers who had never
meditated before were asked to meditate for short periods
Measured gamma wave activity (important because they coordinate
neuron activity) and found much greater gamma wave activity in the monks than the students, even before meditation began.
They concluded that meditation not only affects the brain in the short-term but may also produce permanent changes
Plasticity can be negative.
Examples of this would include prolonged drug use
leading to poorer cognitive functioning and old age
being associated with dementia .Both are due to
changes in the brain.
PLASTICITY EVALUATION 1
Animal Studies : Studies using rats have shown that
environment and life experience positively influence plasticity
in relevant areas of the brain.
Kempermann (1998) found that rats living in complex
environments showed increased neuronal activity in the hippocampus, responsible for spatial awareness and new
memory formation, compared to rats living in lab cages.
This research suggests the brain will adapt and become active in response to environmental pressures, showing direct evidence
for plasticity in rat brains.
PLASTICITY EVALUATION 2
Furthermore, research has found a similar relationship in humans, between neural response and our environment.
Maguire’s (2000) research showed London taxi drivers had increased grey
matter and neural activity in the hippocampus, which is responsible for spatial awareness, navigation and other skills they will have in abundance
due to the demands of their job. Increasing the importance of this evidence, was the finding that time working as a taxi driver was positively correlated with hippocampal volume.
This is significant evidence that the brain changes and develops in response to environment and that plasticity continues to occur to meet the specific demands of our individual lifestyles.
RESEARCH
Maguire et al (2000) studied the brains of London taxi drivers using an MRI
and found significantly more grey matter in the posterior hippocampus than in the matched control group.
This part of the brain is associated with the development of spatial and
navigational skills in humans and other animals.
As part of their training London Cabbies must take a complex test called ‘the
knowledge’, which assesses their recall of the city streets and possible routes. It is also noteworthy that the longer they had been doing the job the more pronounced was the structural difference (a positive correlation).
EVALUATION OF MAGUIRE
+ Control group allows us to say that there is a significant difference between taxi drivers and others. (good design).
+ Use of scientific, objective measurements (MRI)
+ An attempt to study a real world phenomena.
- We can’t be sure that the difference is due to the ‘knowledge’, as they
weren’t tested before. They could have been taxi drivers because of their
already existing difference. (although the positive correlation between
experience and structure makes this less likely)
EVALUATION OF PLASTICITY
+ Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation. Techniques for physical therapy can maintain
improvements.
+ Support from animal studies
- Negative plasticity – the brain’s ability to rewire can have maladaptive
behavioural consequences, e.g. poorer cognitive functioning due to
prolonged drug use or phantom limb syndrome. - Functional plasticity reduces with age
FUNCTIONAL RECOVERY
Following physical injury or other forms of trauma such as infection or the experience of a stroke, unaffected areas are
sometimes able to adapt or compensate for those areas that are damaged.
The functional recovery that occurs in these cases is an example of neural plasticity. Neuro scientists suggest that this can happen quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. Therapy may then be needed.
WHAT HAPPENS IN THE BRAIN DURING RECOVERY?
The brain is able to rewire and reorganise it’s self by forming new synaptic
connections close to the area of damage. Secondary neural pathways that
would not typically be used to carry out certain functions are ‘unmasked’ to
enable functioning to continue. This process is supported by a number of
structural changes.
- Axon sprouting: new nerve endings grow and connect with undamaged areas.
- Denervation supersensitivty axons that do a similar job become more sensitive to allow them to also do that job (compensating for lost connections)
- Recruitment of homologous (similar) areas on the opposite hemisphere to do specific tasks. E.g if Brocas area was damaged then an area on the right might take over
FUNCTIONAL RECOVERY AFTER TRAUMA
Research has shown that when brain cells are destroyed or damaged (due
to stroke or other trauma) the brain rewires itself over time so that some
level of function can be regained. Neurons next to damaged brain areas
can form new circuits that resume some of the lost function.
Two ways in which the brain is able to recover are neuronal unmasking
and stem cells
