Zusammenfassung der Ressource
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.
- Carried out to measure the
effects of wither enrichment or
deprivation to the development of
neurons in the cerebral cortex.
- Method:
- Male rats randomly assigned into 12
sets of 3 (each from the same litter).
- 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.
- Cages:
- 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.
- The enriched environment where 6-8 rats
lived in a "large cage furnished with a variety
of objects with which they could play."
- 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.
- 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.
- The examinations were done in
random order by code number.
- The rats various brain sections were
measured, weighed and analysed to
determine amount of cell growth and
levels of neurotransmitter activity.
- Findings:
- 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.
- There was greater activity of the
nervous system enzyme
acetylcholinesterase found in the brain
tissue of the enriched rats.
- Cortical thickness increases even further
if the rats are placed with other rats.
- The combination of having company and many
interesting toys created the best conditions for
developing cerebral thickness.
- 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.
- The ratio of RNA to DNA was greater for
the enriched rats (higher levels of chemical
activity in the enriched rats brains).
- The synapses of the enriched rats brains were
50% larger than those of the deprived rats.
- Problems:
- Animal cruelty.
- Androcentric.
- Rats cannot be generalised to humans.
- Small sample size.