Sleep and EEGS Flashcards
What is sleep and how is different from a coma
Sleep :State of unconsciousness from which an individual can be aroused via stimuli of light, touch, perception.
Coma: state of unconsciousness from which an individual CANNOT be aroused through stimuli.
What is sleeping due to?
How has this been verified?
Occurs due an inhibitory process which occurs in the pons- impulses must be send through down the mid-line of the pons (damage to this area leads to sleep deprivation)
Which are the neurotrasmitters involved in controlling sleep activity?
Serotonin and melatonin
Which impulses control sleep activity?
Neurones which are fired from the reticular formation of the midbrain
Where are the impulses from the reticular formation sent to?
- The hypothalamus
- The thalamus
- The cortex
What controls the circadian rhythm of electrical impulses
Hypothalamus and Superchiasmatic nuclei are also related to control of slee
What does circadian mean?
It defines a group of patterns in the body which change over 24 hours
What stimuli do the SCN respond to?
- Time zone changes
- Day/night
- Work patterns
Where is the SCN located?
What does this implicate?
Located just above the optic chiasma so must receive info from the brain
How does the sleep cycle work?
- Excitatory neurones are activated (from sleep centres in reticular formation) in the ascending reticular activating system (ARAS) of reticular formation
- These excitatory neurones release impulses which stimulate excitatory pathways in the CNS and PNS
- A positive feedback system allows these pathways to stay activated for a very long period of time
- These cells slowly become fatigued
- Peptides from the sleep centres oft reticular formation are released- dominate over excitatory pathways= lead to sleepiness
How do people who are blind dream?
- If bind from birth have auditory dreams
- If they become blind- they will slowly lose their ability to dream in vision
How do dolphins and birds dream?
One side of the brain awake, one asleep.
What does EEG measure
ecords electrical patterns of the brain
Measures amplitude of waves (size of wave : from 0-200 microV)
Measures frequency of waves ( measures the number of waves in 1 second 0-50)
Different EEGs based on state of consciousness
- Awake: high frequency, low amplitude
- Asleep: low frequency, high amplitude
4 types of wave seen on an EEG
Alpha
Beta
Theta Gamma