Transcript Biological Rhythms

Biological Rhythms: Circadian rhythms
Animal research and justification
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
Biorhythms
• 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
The SCN
Justifying animal research using the
CBA - Cost benefit analysis
Costs
• Making decisions
based on a CBA:
– Quality of research
– BUAV campaigns
against Vivisection
studies
– Benefits to
humankind
– Suffering to
animals
– Can we generalise
Benefits
• 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
Writing commentary for RWA and ethics
• 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 ..
.... occurred when people should have been sleeping.
• Therefore this research must be completed to
alleviate human suffering.
Patricia DeCoursey (2000)
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.
Morgan (1995) Hamster research
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.
IDEA: Unethical,
generalisable,
extrapolation,
BUAV, Speciesism,
Ralph (1990) Hamster study
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
Justification of animal research:
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