Week 3 (Modules 5-6)

Question 1

What is the main Zeitgeber to synchronizing circadian rhyths to local time?

Answer 1

light

Question 2

What are ‘black box’ models of circadian rhythms?

Answer 2

Models that are ‘conceptual’ - represent the elements and interactions that may be present in the brain and body which explain properties of circadian rhythms

Question 3

Relations between brain areas are ____, which means ______

Answer 3

• reciprocal

- if one area sends signals to another, it is also able to receive signals from that region

Question 4

What is the best time to see how social cues affect the circadian rhythm of an animal?

Answer 4

When they are very young and dependant on their parents

Question 5

What is one way in which a rat fetus’s internal clock becomes entrained to local time?

Answer 5

Through hormones from the mother, such as melatonin when it is the mother’s night-time

Question 6

What is a possible explanation for how social stimuli can affect an animal’s biological clock?

Answer 6

The social stimuli affect the animal’s activity-rest cycle, which causes inputs to be sent to the circadian clock

Question 7

How can a rat’s or mouse’s circadian rhythm be altered without the use of light?

Answer 7

• Wheel-running (or arousal) at night decreases their tau slightly
• Wheel-running during the day increases their tau

Question 8

How can phase shifts in rats or mice be prevented?

Answer 8

Stress

Question 9

In rodents, how does exercise affect phase shift effects?

Answer 9

Inhibits them

Question 10

What inhibits entrainment from daily feeding schedules in rats?

Answer 10

Constant darkness or constant light

Question 11

What are three ways rats may be able to have food-anticipatory behaviour separate from their circadian rhythm?

Answer 11

• Separate biological clock for food (food-entrainable pacemaker)
• Internal hourglass (controlled by hunger)
• Internal stopwatch (rat can time how long until next meal)

Question 12

Evidence points to rat food-anticipatory behaviour being part of a ______, because _____

Answer 12

• circadian rhythm

- their behaviour persists even after several days with no food at their scheduled feeding time

Question 13

In rats, food anticipation does not occur unless _____

Answer 13

Meals are given at circadian intervals

Question 14

What evidence is there for the existence of multiple food-entrained clocks in rats?

Answer 14

Rats are able to entrain to multiple meals at different circadian intervals

Question 15

What is temporal niche switching?

Answer 15

Feeding animals during their usual rest phase