Rosenzweig and Bennet

Aim: 1972 Animals raised in highly stimulating environments will demonstrate differences in brains growth and chemistry when compared with animals reared in dull environments.
1. Carried out to measure the effects of wither enrichment or deprivation to the development of neurons in the cerebral cortex.
Method:
1. Male rats randomly assigned into 12 sets of 3 (each from the same litter).
2. Put into 1 of 3 circumstances to create a control group, and 2 experimental groups: enriched cage, deprived cage. Here they spent 4-12 weeks.
3. Cages:
  1. The control group were placed in the standard laboratory colony cage which contained several rats in a adequate space with food and water always available.
  2. The enriched environment where 6-8 rats lived in a "large cage furnished with a variety of objects with which they could play."
  3. The deprived environment was a slightly smaller cage isolated in a separate room in which the rat was placed alone with adequate food and water.
4. The rats were then killed and autopsies were carried out on their brains to determine differences between the brains of the enriched rats vs the deprived rats.
5. The examinations were done in random order by code number.
6. The rats various brain sections were measured, weighed and analysed to determine amount of cell growth and levels of neurotransmitter activity.
Findings:
1. The cerebral cortext (responds to experience and is responsible for movement, memory, learning and all sensory input) of the enriched rats was significantly heavier and thicker.
2. There was greater activity of the nervous system enzyme acetylcholinesterase found in the brain tissue of the enriched rats.
3. Cortical thickness increases even further if the rats are placed with other rats.
  1. The combination of having company and many interesting toys created the best conditions for developing cerebral thickness.
4. There were no significant differences found between the two groups of rats in the number of brain cells (neurons) but the enriched rats produced larger neurons.
5. The ratio of RNA to DNA was greater for the enriched rats (higher levels of chemical activity in the enriched rats brains).
6. The synapses of the enriched rats brains were 50% larger than those of the deprived rats.
Problems:
1. Animal cruelty.
2. Androcentric.
3. Rats cannot be generalised to humans.
4. Small sample size.

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Rosenzweig and Bennet

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	Created by leonie1997 about 10 years ago