Topic 11- Endogenous Pacemakers & Exogenous Zeitgebers

Question 1

PEEL 1
Hamster Animal studies

Answer 1

P- Animal studies support the role of SCN as an endogenous pacemaker.
E- SCN neurons from hamsters bred to have abnormally short circadian rhythms were transplanted into normal hamsters, which displayed the abnormal rhythm too.
E- Further confirmation came in the reverse experiment, when the SCN neurons from normal hamsters were transformed into abnormal hamsters, they changed to a normal 24 hr circadian pattern.
L- Supporting the importance of the SCN in regulating the 24 hr circadian rhythm.

Question 2

PEEL 2
role of melanopsin/ blind ppl

Answer 2

P- The role of melanopsin is supported by studies of blind ppl.
E- Modt blind ppl who still have light perception have normally entrained circadian rhythms.
E- Some blind people who completely lack visual perception, and have no functioning rods and cones still entrain their circadian rhythm to daylight.
L- Suggesting the pathway from retinal cells containing melanopsin to the SCN is still intact in the person.

Question 3

PEEL 3
Jet lag

Answer 3

P- Using light exposure to avoid jet lag, Burgess exposed volunteers to light treatment in order to shift their sleep-wake cycle.
E- Participants sleep patterns and melatonin levels were monitored in a lab.
E- Participants who had been exposed to bright light felt sleepy 2 hrs earlier in the evening and woke up 2 hrs earlier in the morning.
L- Showing circadian rhythms can be shifted by light exposure.