Biological Rhythms

Question 1

Describe 3 basic properties of circadian rhythms shown by mice

Answer 1

1. Wheel running rhythm persists in constant dark with endogenous period around 24 hours
2. Entrainment of rhythms controlled by light as a zeitgeber
3. Phase shifts response to new light/ dark pattern

Question 2

What does EEG record

Answer 2

Summer activity of neuronal populations in a continuous reading

Brain activity patterns

Question 3

Describe the clinical importance of EEG

Answer 3

Availability of predictable waves associated with behaviours

Instant measurement

Question 4

What are the two definitions of sleep

Answer 4

Behaviourally: as a normal absence of consciousness

Electrophysiology: a pattern of specific brain wave activity

Question 5

Describe the patterns of the awake brain

Answer 5

15-30Hz

Alpha and beta activity

Question 6

Describe the patterns of stage 1 sleep

Answer 6

4-8Hz

Theta activity

Drowsiness

Question 7

Describe stage 2 brain activity

Answer 7

10-15Hz

Spindle

Oscillations

Question 8

Describe stage 3 brain activity

Answer 8

2-4Hz

20-50% delta

Question 9

Stage 4 brain activity

Answer 9

0.5-2Hz

Delta activity

More than 50% deep sleep

Question 10

REM brain activity

Answer 10

15-30Hz

Resembles beta activity

Question 11

How many sleep cycles a night?

Answer 11

• 5
• REM duration increases
• deep sleep present for only first two
• heart rate and respiration peak during REM

Question 12

Sleep under both Homeostatic and circadian regulation?

Answer 12

Homeostatic: when we are sleep deprived the brain increases need for sleep

Circadian: also controlled by fluctuating circadian cycle

Question 13

What are the 3 neural systems of sleep

Answer 13

Forebrain system: can dependently support SWE
Brainstem: activates the forebrain into waking up
Pons: triggers REM sleep