Neuroplasticity

1. Neuroplasticity By Bekky, Estelle, and Kassie.

2. 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.

3. Sensory Deprivation • Depriving the body of 5 senses:-touch-taste-smell-hearing-seeing • E.g. = taking away...food or light or social communications

4. 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.

5. 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.

6. 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)

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.