1. Brain Development
By Jay Patel

2. Development in the womb
3rd week – embryo formed 3 main parts of the brain
4th week – brain begins functioning
4th month onwards – brain making neural connections to all parts of the body (synaptogenesis)
8th month – foetus can recognise and remember its mother’s voice

3. Animal Models Similarities between animal and human brains
So same experimental results usually obtained
Using humans unethical so animal models used
E.g. Hubel and Wiesel’s experiment on development of ocular dominance columns in kittens

4. Ocular Dominance Columns
Visual cortex part of cerebral cortex at back of brain
Neurones in visual cortex receive and process visual information
Neurones grouped together in ocular dominance columns
Arranged in an alternating pattern

5. Hubel and Wiesel Experiment
Stitched closed one eye from each kitten
When unstitched, kittens blind from previously stitched eye
Ocular dominance columns of stitched eyes decreased in size, columns of unstitched eyes increased (switched dominance)
When repeated on adult cats, they recovered full normal vision and ocular dominance columns unchanged
Same results found on young and adult monkeys
So both eyes need to be visually stimulated in early stages of life for normal visual development

6. Critical Window
Period of time in early stages of life when critical for humans to be exposed to visual stimuli for normal visual development
Hubel and Wiesel experiment – animal model applied to humans
Cataracts in humans – babies and adults

7. Animals in Medical Research
Moral and ethical issues
Against
For
Pain/distress caused to animals
Only done when necessary, scientists follow strict rules (painkillers/anaesthetics used to minimise pain)
Alternatives to using animals in research (e.g. human cell cultures and computer models)
Cell cultures and computers not true representation of how cells may react when surrounded by other body tissues, only way to study behaviour
Animals different to humans, drugs tested on animals may have different effects on humans
Animals are similar to humans, animal research has led to many medical breakthroughs (e.g. antibiotics, insulin, organ transplants)
Animals have right to not be experimented on – animal right activists
Humans have greater right to life than animals because they have more complex brains