9. Endogenous Pacemakers and Exogenous Zeitgebers

• What are endogenous pacemakers?

  Internal bodily regulators of biological rhythms
• How do endogenous pacemakers affect biological rhythms?

  They entrain biological rhythms to conform to certain cyclical periods
• What is an example of a cyclical period for circadian rhythms?

  One cycle every 24 hours
• What role does the suprachiasmatic nucleus (SCN) play in biological rhythms?

  It processes information about daylight and day length
• How does the SCN receive information about light?

  Through the eyes, processed by the visual area in the occipital lobe
• What happens to melatonin release during nighttime?

  Increased melatonin release triggers decreased serotonin production
• What effect does light exposure have on melatonin release during the daytime?

  It triggers the pineal gland to release less melatonin
• What was the main finding of DeCoursey et al (2000) regarding SCN lesions in chipmunks?

  The majority of the experimental group had been killed within 80 days
• What did Ralph et al's research on SCN cells from hamsters demonstrate?

  The restored rhythms exhibited the period of the donor genotype
• What are exogenous zeitgebers?

  External environmental changes affecting biological rhythms
• How do social cues function as exogenous zeitgebers?

  They signify when to wake up and when to fall asleep
• How can one avoid jet lag according to the study material?

  By accustoming oneself to the sleeping and eating times of the destination
• What was demonstrated by Siffre et al (1967) regarding light and the sleep-wake cycle?

  Light can entrain biological rhythms even when not detected by the eyes
• What did Campbell and Murphy's research show about light exposure?

  It produced deviations of 3 hours in participants' sleep-wake cycles
• What did Damiola et al's findings suggest about the SCN's influence?

  The SCN's influence may be overestimated due to peripheral oscillators
• What are peripheral oscillators?

  Collections of cells that act independently of the SCN
• What ethical issues arise from animal research in biopsychology?

  Deliberate harm to animals breaches ethical guidelines
• What is a cost-benefit analysis in the context of animal research?

  Assessing whether ethical costs outweigh the benefits of findings
• What limitation is associated with generalizing findings from animal studies to humans?

  Differences in physiology and circadian rhythms limit ecological validity
• What case did Miles et al (1977) report regarding circadian rhythms?

  A man with a sleep-wake cycle of 24.9 hours that could not be changed
• What does the case reported by Miles et al (1977) suggest about exogenous and endogenous factors?

  Their influence may be overestimated