Brain Development

Question 1

Describe structure and role of the visual cortex

Answer 1

• area of cerebral cortex, found at the back of the brain
• receives and processes visual info

Question 2

Describe how visual cortex receives visual information

Answer 2

• neurones in visual cortex receive info from either left or right eye
• neurones are grouped in ocular dominance columns; columns of same size arranged in an alternating pattern (L,R,L,R…)

Question 3

Outline Hubel and Wiesel’s experiment into visual development

Answer 3

• carried out research on animals with similar brain structure to humans
  ~ stitched kittens eye closed soon after birth
  ~ after 3 months, found kittens were blind in stitched eye
  ~ looked at neurone activity in visual cortex, found ocular dominance columns corresponding to stitched eye were smaller than normal while those corresponding to open eye were larger than normal
• repeated this with adult cats —> no blindness occurred + no changes in distribution of ODCs

Question 4

What did Hubel and Wiesel conclude from their research?

Answer 4

Without early stimulation, ODCs are unable to develop normally

Question 5

Define critical period

Answer 5

A period in early development where synapses between neurones are strengthened, must occur for proper development

Question 6

Describe role of visual stimulation during critical period

Answer 6

• soon after birth neurones begin to form connections —> neurones
• both eyes must be visually stimulated for neurones in VC to be correctly organised
• synapses which pass on nerve impulses are strengthened and become permanent part of the visual cortex
• those that do not are lost + cannot be reformed

Question 7

Give ethical argument for use of animals in research

Answer 7

• new drugs must be tested on whole organism, not group of cells
• more ethical than using humans, testing drugs we don’t know are safe on humans is unethical
• only carried out on animals when no alternatives, governed by strict regulations
• animal anatomy is similar to humans so research is transferable

Question 8

Chive ethical argument against use of animals in research

Answer 8

• testing in human cells/tissue or computer models provides an alternative
• many believe animals should have same rights as humans -consent, welfare
• animals still suffer pain and distress despite regulations, may be killed to analyse tissues
• animal and human anatomy ≠ identical, medications may have a different effect on humans than on animals