Module 11

Question 1

To be entrained to local time, the circadian clock must have access to information about ______ (photic entrainment) and ______ (non-photic entrainment)

Answer 1

• the timing of dawn and dusk

- the timing of meals, the behavioural state of the animal, or other stimuli

Question 2

Rods are specialized to ___ vision and cones are specialized for ____ vision

Answer 2

• night

- day

Question 3

Rods and cones contain ____ that absorb light

Answer 3

photopigments

Question 4

Absorbtion of light triggers _______ that alter ______

Answer 4

• intracellular second messenger pathways

- the amount of neurotransmitters that rods and cones release

Question 5

Changes in neurotransmitter release by rods and cones alters _______ which, along with _____, send information to _____

Answer 5

• Neural activity in horizontal and bipolar cells
• amacrine cells
• retinal ganglion cells

Question 6

What are the output neurons of the retina?

Answer 6

Ganglion cells

Question 7

The axons of ganglion cells make up the _____

Answer 7

Optic nerves

Question 8

How does loss of rods and cones in mice affect their circadian response to light?

Answer 8

Does not affect their ability to phase shift and entrain to light

Question 9

How does the functioning of melanopsin-containing retinal ganglion cells work?

Answer 9

The cells have long dendritic trees, which are photoreceptive and send information to the SCN

Question 10

Melanopsin-containing retinal cells are also called ______

Answer 10

Intrinsically photoreceptive melanopsin-containing ganglion cells (ipRGCs)

Question 11

What happened to melanopsin KO mice?

Answer 11

They still responded to light cues

Question 12

What gene mutation is required to make mice circadian blind?

Answer 12

Mutation to make the melanopsin gene undergo cell death, eliminating ipRGCs that connect to the SCN

Question 13

The retina innervates the SCN directly through the ______

Answer 13

Retinohypothalamic tract (RHT)

Question 14

The RHT originates from neurons in the ______

Answer 14

Intergeniculate leaflet (IGL) of the thalamus

Question 15

SCN action potentials code for ____

Answer 15

Total illuminance - the total number of photons falling on the retina

Question 16

SCN neurons have ______ receptors, which is the main _____ in the brain

Answer 16

• glutamate

- depolarizing transmitter

Question 17

What is most likely the photic neurotransmitter for shifting SCN clocks?

Answer 17

Glutamate

Question 18

In Syrian hamsters, NDMA injections to the SCN early in the subjective night cause ______, and late in the subjective night cause ______ - the same as _______

Answer 18

• phase delay
• phase advance
• short light pulses

Question 19

What happens if a drug that blocks glutamate receptors is injected before a light pulse?

Answer 19

The pulse does not induce a phase shift

Question 20

What does cfos do?

Answer 20

Expression is turned on when neurons are depolarized, correlated with phase shifting

Question 21

IGL lesions that eliminate ___ in the SCN prevent entrainment of free-running rhythms by a ______

Answer 21

• NPY

- daily exercise schedule

Question 22

In Syrian hamsters, stimulation of the IGL with electric currents or stimulation of the SCN with NPY both _______

Answer 22

Induce phase shifts like those by exercise in the middle of the subjective day

Question 23

NPY neurons are activated by _____

Answer 23

Exercise

Question 24

In mice, lesions to the median raphe prevent _______

Answer 24

Full entraining effects of exercise in mice

Question 25

Raphe nuclei use _____ as a neurotransmitter

Answer 25

Serotonin (5HT)

Question 26

Which neurotransmitters appear to be involved in non-photic entrainment, and which one is necessary

Answer 26

NPY (necessary) and 5HT

Question 27

In hamsters, stress activates cells in the _____, which project to the ____, which inhibits _____, preventing the activation that is needed to _____

Answer 27

• Dorsal raphe
• IGL
• NPY neurons in the IGL
• Release NPY into the SCN to induce a phase shift

Question 28

The photic PRC can be reproduced using ______

Answer 28

Injections of glutamate into the SCN

Question 29

The PRC in rats to melatonin causes a phase _____ near _____

Answer 29

• Advance

- CT12

Question 30

The PRC to physical restraint is _____

Answer 30

The mirror image to melatonin