Aims
To know the biological clock in control of the
Circadian Rhythm
To understand the difference between Endogeous
Pacemakers and Exogenous Zeitgebers
To be able to evaluate animal research ethics/studies in regards RWA and justification

• A biological rhythm is any change in a biological activity that repeats periodically.
Often synchronised: Daily, Monthly and annual.
Circadian = 24 hour cycle; S/W cycle
Infradian = 24+ hour cycle; Menstrual cycle
Ultradian = <24 hours; Sleep

Costs
• Making decisions Benefits based on a CBA:
– Quality of research
– BUAV campaigns against Vivisection studies
– Benefits to humankind
– Suffering to animals
– Can we generalise

• Making decisions based on a CBA
– cost benefits analysis:
– Quality of research
– BUAV campaigns against Vivisection studies
– Benefits to humankind
– Suffering to animals
– Can we generalise

• Research into circadian rhythms have huge real world application.
• A common criticism of animal research is the unethical suffering caused by vivisection studies.
• For example, .... deCoursey/ralph/morgan .....
• However, a cost benefit analysis would suggest that the research is justifiable.
• For example, the exxon vladez/chernobyl disasters ..
.... o ccurred when people should have been sleeping.
• Therefore this research must be completed to
alleviate human suffering.

IDEA: Cruel, Unethical, costs benefits analysis, generalisable, extrapolation,
Rights, Speciesism, Equality, Respect,
BUAV, Home office license, 3RRR’s
• She removed/damaged the SCN
in 30 chipmunks. The chipmunks were returned to their natural habitat.
• After 80 days, significantly more of the SCN-lesioned chipmunks had been killed by weasels.
• This was presumably because these chipmunks remained
awake in their burrows and the
weasels could hear the noise and were able to locate the chipmunks.

IDEA: Cruel, Unethical, costs benefits analysis, generalisable, extrapolation,
Rights, Speciesism, Equality,
Respect, BUAV, Home office license, 3RRR’s
• He gave hamsters brain transplants of SCN from a mutant strain (which he bred) whose biological rhythms have a shorter cycle.
• The recipients adopted the same activity cycles as the mutant strain.
• The finding that animals transplanted with the SCN adopts the same activity patterns as their donors, along with the fact that the circadian rhythm cannot be
manipulated beyond certain limits, suggests that bodily rhythms are primarily endogenous.

Ralph (1990) also transplanted an
SCN from a free running (25 hour) hamster into the mutants; who adopted a 25 hour rhythm. The mutant gene was tau which caused the 20 hour cycle. Showing how genes affect behaviour.
• Aim: To show that the SCN generates the circadian rhythm in mammals.
• Sample: hamsters, with a genetic abnormality affecting their circadian cycle that resulted in a 20-hour circadian cycle, rather than a 24-hour one.
• Method: Their SCNs were removed and placed in the brains of a group of hamsters with a normal 24-hour cycle.
• Result: The experimental group shifted to a 20-hour cycle.
• Conclusion: the hamsters’ circadian cycle was regulated by the SCN. When normal hamsters were given an abnormal SCN they developed an abnormal circadian cycle.

RWA
Working when we should be sleeping!
Using SCN research to help remove Human error from shift work
• Negative effects of sleep deprivation
– e.g. decreased attention
– slowing of reasoning skills
– impaired reaction could have serious consequences on the ability to do work or drive safely.
Possible justification for animal research
Practical application of Psychology in the real world