Biopsychology - endogenous pacemakers and exogenous zeitgebers

Question 1

what are endogenous pacemakers

Answer 1

• internal body clocks that regulate biological rhythms
• pineal gland and melatonin
• superchiasmatic nucleus

Question 2

what is the superchiasmatic nucleus

Answer 2

• hypothalamus of each hemisphere
• receives information about light
• above the optic chiasm
• occur when eyes are closed - biological clock can still work when asleep

Question 3

what animal study was conducted with the SCN

Answer 3

Decoursey et al (2000)
- destroyed SCN connections in 30 chipmunks
- returned to natural habitat and observed
- end of the study several had been killed by predators

Question 4

what is the role of the pineal gland and melatonin

Answer 4

• SCN passes information to the pineal gland
• at night produces melatonin
• melatonin induces sleep

Question 5

what are the limitations of endogenous pacemakers

Answer 5

Interactionist system
- pacemakers cannot be studied in isolation
- lowers validity of research

Ethics
- ethical issues with the chipmunks
- cannot be generalised

Question 6

what are exogenous zeitgebers

Answer 6

• external factors that affect our biological rhythms
• light on sleep wake cycle

Question 7

what is the effect of light on the sleep wake cycle

Answer 7

• resets the SCN
  Campbell and Murphy (1998)
• light may be detected by skin receptors even when information is received by the eyes
• 15 pps woke up at various times when a light pad was shone on the back of their legs

Question 8

what are the limitations of exogenous zeitgebers

Answer 8

Environmental determinism
- don’t have the same effect in all environments
- people who live in countries with little sunlight have similar sleep patterns all year round even if they spend 6 months in the dark

Case study evidence
Miles (1977)
- young man blind from birth had a circadian rhythm of 24.9 hours
- despite social cues (meals) his sleep wake/cycle couldn’t be adjusted