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Neuroplasticity
By Bekky, Estelle, and Kassie.
Brain plasticity
• Brain’s ability to rearrange different
connections between its neurons
(electrochemical message transmitter)
• Experience and learning cause the changes
that occur in the structure of the brain.
• Different challenges that the environment
contains cause the brain to adapt to it.
Sensory Deprivation
• Depriving the body of 5 senses:
-touch
-taste
-smell
-hearing
-seeing
• E.g. = taking away...food or light or social
communications
Rosenweig and Bennett (1972)
• AIM: believed that animals raised in highly stimulating
environments will demonstrate differences in brain growth
and structure when compared with animals exposed to a
dull environment – measure the effect of either enrichment
or deprivation to the development of neurons in the
cerebal cortex.
• METHOD: rats placed into one of two environments.
Enriched environment included interesting toys to play with
and lots of food. The deprived environment was the
opposite (no toys etc). 12 male rats in each for 4-10 weeks.
Rats then sacrificed and autopsies carried out on their
brains to determine differences developed between brains
of the enriched rats compared to deprived rats.
Results
• When replicated the results were the same (more valid)
• Cerebral cortex (responds to experience and responsible for
movement, memory, learning and sensory input) was
heavier and thicker in the enriched rats than the deprived.
• Greater activity of nervous system memory enzymes found
in brain tissue of enriched rats.
• Enriched rats produced larger neurons.
• RNA DNA ratio greater in enriched rats (higher level of
chemical activity in enriched rats).
• Synapses of enriched rats’ brain were 50% larger than
those of the deprived rats.
Limitations
• Unethical – physical and psychological harm,
consent, withdrawal, rats killed after
experiment.
• All male rats (and humans are not rats)
• Human error involved (analysing the brain
sections etc)
Strengths
• Experiment repeated
• Coding order was random (no
predictions/expectations made)
• Rats from the same litter (controlled)
• Same amount of the section of brain each
time (machine was used)
• 2 groups or rats to compare results.
Merzenich’s experiment on monkeys
• Outline: Michael Merzenich and Clinton
Woosley’s experiment on monkeys was based on
observation of what occured in the brain when
one peripheral nerve was cut and subsequently
regenerated.
• Aim: The aim of this experiment was to show that
the adult brain was plastic.
• Method: The two scientists micromapped the
hand maps of monkey brains before and after
cutting a peripheral nerve and sewing the ends
together.
Results
• Results: They realised that the hand map in the brain that
was expected to be jumbled was nearly normal. Merzenich
concluded that if the brain map could normalize its
structure in response to abnormal input, the prevailing
view that we are born with a hardwired system had to be
wrong, therefore the brain had to be plastic.
• Results: They realised that the hand map in the brain that
was expected to be jumbled was nearly normal. Merzenich
concluded that if the brain map could normalize its
structure in response to abnormal input, the prevailing
view that we are born with a hardwired system had to be
wrong, therefore the brain had to be plastic.
Limitations
• Although monkeys are close in relation to
humans, they are not humans therefore you
can’t generalise.
• It could be considered unethical to do these
experiments on monkeys due to the lack of
consent, and may have caused physical harm.
• Experiment was not repeated. Only done on
one group of monkeys.
Strengths
• Since we are getting this information from
monkeys, it is close to being accurate.
• Was a really important study for
neuroplasticity and showed great results.