Sleep

Question 1

How can we define sleep?

Answer 1

Sleep is a continuum of states

Sleep is higly risky - therefor must be vitally important.

Question 2

How can we measure sleep?

Answer 2

EEG: a tool for measuring sleep.
- Allows to measure the synchronized activity of neurons in cerebral cortex.

• EEG can identify stages of sleep: 

- Most sleep is "non-REM" rype
- Unconscious 
- Gradient of depth from awake to deep sleep

Question 3

How is sleep regulated

Answer 3

Sleep is regulated by two parallel mechanisms, homeostatic regulation and circadian regulation, controlled by the hypothalamus and the suprachiasmatic nucleus (SCN), respectively

Question 4

What controls the ascending arousal system?

Answer 4

Hypothalamus - Responsible for controlling primitive body functions (e.g. body temperature, blood pressure), and Behaviours (feeding, sex, behaviours defensive flight/fight)

- Where the brain’s clock  is  found 

Cells in the suprachiasmatic nucleus (SCN) of the hypothalamus act as intrinsic timers with a 24 hour cycle

Question 5

The ascending arousal system control

Answer 5

the firing mode of forebrain neurons and thus determine arousal state

Question 6

Why do we sleep?

Answer 6

The brain is a complex system with very high energy demands

- Maintenance is  required  to  keep it running well 
- “Downtime”  can make  maintenance  less disruptive

Question 7

What happens during sleep after learning?

Answer 7

• During sleep, place cells fire in short bursts called “ripples”
  
  • Many place cells participate in each ripple event
  • Place-cell sequences are “replayed” during sleep after the event
  • Replay occurs approx. 20 x faster than original speed