Animal Research

Question 1

BRAIN AND BEHAVIOUR

Answer 1

Theory: Neuroplasticity
Animal study:
Merzenic et al - owl monkeys
- Electrodes inserted into the cortical area responsible for the hand
- Various areas of the hand stimulated to note which electrode was responding to stimulation
- Third digit amputated
- After 62 days a remapping was done to see how the cortical area changed after amputation
- results: The areas responsible for digit 2 and 4 got larger and occupied the area previously responsible for digit 3
- evaluation:
Credibility - good internal validity, all variables well controlled
Generalizability - hard to generalise as the study was only conducted for the hand of an owl monkey and we can’t predict the results for other areas of the cortex nor for other species
Ethical considerations - harm done to the monkeys (amputation), however they were under anaesthesia

Human study:
Draganski et al - jugglers

Question 2

HORMONES

Answer 2

Hormone: Vasopressin
Animal study:
Winslow et al - prairie voles
- placebo or vasopressing antagonist
- put into a cage with a female and left to mate
- after mating they were put into a cage with 3 “rooms”: the sexual partner, another female, empty
- results: The voles that had been injected with the placebo spent their time with their mate. Those that were injected with the antagonist spent equal time with the mate and the other female.
- Evaluation:
strong internal validity, no major ethical concerns, animal model, vasopressin present in other animals that are not monogamous

Human study:
Walum et al - married men
- sampled 500 men to see whether they had a genetic variation that reduced vasopressin levels
- Likert-scale test to measure their attatchment to their partner
- results: lower vasopressin -> lower satisfaction (30 vs 15% had thought about divorce)
- evaluation:
- level of vasopressing never actually measured, vasopressing present in non-monogamous animals, only men, standardised test doesn’t account for individual differences

Question 3

GENETICS

Answer 3

Gene: gene that regulates the production of monoamine oxidase A (MAOA) (MAOA is an enzyme that breaks down serotonin and norepinephrine)

Animal study:
Cases et al - transgenic mice
- gene deleted
- introduced to an “intruder”
- control just checked out the other mouse and the knockout mice were aggressive towards it
- high levels of aggression found in male transgenic pups
- autopsy showed very high levels of serotonin in knockout sample
- conclusion: MAOA deficiency in humans may be a cause of aggressive tendencies
- evaluation:
- ethical concerns, animal model limitations, well controlled

Human study:
Caspi et al 2002 (NOT THE DEPRESSION ONE)
- longitutinal study - 25 years
- over 1000 children from NZ
- results: low enzyme production MAOA gene + abuse = more anti-social/aggressive/criminal behaviour ; only gene = no significant effect ; no gene = little difference between abuse and no abuse
- evaluation:
- longitutinal, large sample, only boys, generalisations

Question 4

ETHICS

Answer 4

Merzenic et al

Cases et al