Brain Ryhtms and Sleep

Question 1

What is a cue that synchronizes a Biorythm with the environment called?

Answer 1

Zeitgeber

Question 2

Difference in Phase shifts between Diurnal and Nocturnal animals?

Answer 2

Diurnal get longer free running period in constant darkness
Nocturnal get shorter free running period in constant darkness

Question 3

What is the Biological clock?

Answer 3

Suprachiasmatic nucleus

Question 4

How does the SCN get cues?

Answer 4

Specialized retinal ganglion cells project to SCN, contain melanopsin (Blue light pigment)

Question 5

What is the molecular clock and how does it work?

Answer 5

Two proteins Clock & Cycle form a dimer. This dimer promotes transcription of two genes Period(per) and Chryptochrome(cry). per and cry proteins form a complex that enters the nucleus and inhibits Clock&Cycle. No new proteins until complex degrades ~ 24 hours. Ganglion cells that detect light release Glutamate into the SCN -> promotes per production and shifts cycle

Question 6

Which hormones are involved in sleep and where are released?

Answer 6

SCN promotes melatonin release from pineal gland during dark.
SCN promotes release of glucocorticoids from adrenal gland during light. (mobilizes glucose for cellular activity)

Question 7

Non-circadian rythms

Answer 7

Circannual - Yearly (Bird migration)
Ultradian - less than day ( human eating)
Infradian - more than day( Menstrual cycle)

Question 8

How can different sleep stages be measured?

Answer 8

Electroencephalogram (EEG) brain activity
Electromyogram (EMG) muscle activity
Electrooculogram(EOG) eye movement

Question 9

In which species has REM sleep been observed?

Answer 9

Birds, Mammals and reptiles

Question 10

Functions of REM?

Answer 10

Brain development: infants have more REM
Implicit memory formation
Restoration of Brain function: interstitial space increases 60%, allow clearance

Question 11

Effect of Brain lesions on sleep?

Answer 11

Transection between medulla and Spinal cord -> regular sleep wake cycle
Incision in midbrain- only SWS

Question 12

What are the four interacting regions that underlie sleep?

Answer 12

Basal forebrain: generates SWS
Reticular formation: regulates Wakefullness
subcoeruleus( sublaterodorsal nucleus (SLD)) triggers REM and inhibits muscles

Question 13

What are the 4 functions of sleep?

Answer 13

Memory consolidation
Niche adaptation
Energy conservation
Body restoration