Zusammenfassung der Ressource
Sleep & Biological
Rhythms
- Stages of Sleep
- Stage 1
- Light sleep, irregular
low voltage waves
- Stage 2
- Sleep Spindle
- Short bursts of
12-14Hz waves
- K-Complex
- Sharp high
amplitude negative
waves, smaller slow
positive waves
- Stage 3 & 4
- Slow, large amplitude waves
- Deepest sleep
- REM Sleep
- Function
- Discards useless
connections
formed in the day
- Assists in memory formation & motor skills
- Moving eyes increase O2 supply to cornea
- Irritability, anxiety, impaired concentration
- Rats die from no REM sleep
- Desynchronized EEG activity
- Rapid eye movements
- Muscular paralysis
- REM Rebound
- 1 Cycle = 90mins
- Brain
Activity
- Measurements
- EEG
- Electroencephalograph
- measures electrical
potentials by
synchronicity
- net avg of all
neuron activity
- EMG
- Electromyogram
- electrical potential
recorded from electrode
placed on muscle
- detects muscle movement
- EOG
- Electro-oculogram
- electrical potential recorded from
electrode placed around eye
- detects eye movements
- REM Sleep
- Alpha
- Relaxation
- Smooth, 8-12Hz
- Beta
- Arousal
- Fairly slow,
13-30Hz
- Theta
- Stage 1 & REM
- 3.5-7.5 Hz
- Delta
- Stage 3 & 4
- Less than 4Hz
- Wakefulness
& Arousal
- Neurotransmitters
- ACh
- Key player, keeps you
awake but triggers REM
- Pons & Basal Forebrain
- produce activation &
cortical desynchrony
- Faster REM
- NE
- Keeps you awake
- Catecholamine agonists
produce arousal &
sleeplessness
- Locus Coeruleus in dorsal pons
- 5-HT
- Activates Behavior
- Raphe Nuclei
- NE & 5HT
disrupts REM
- Physiological
Mechanisms
- Hypocretin
- Peptide (orexin)
produced by neurons
located in hypothalamus
- Orexin = motivation
to stay awake
- Destruction = narcolepsy
- VLPA
- Group of GABA neurons in preoptic
area, activity suppresses alertness &
behavioral arousal, promotes sleep
- Destruction = total insomnia, coma, death in rats
- Endogenous Cycles
- Endogenous: generated by body
- Circadian Rhythm
- wakefulness & sleep
- hormones secretion
- Circannual Rhythm
- mostly in animals
- Allows conservation of energy
for future possible events
- Sleep Abnormalities
- Insomnia
- Onset, Maintenance, Termination
- Sleep Apnea
- Inability to breathe while asleep
- Narrow Airway (obese)
- Brain mechanisms for
respiration fail (elderly)
- Narcolepsy
- Sudden attacks of
sleepiness
- Hypnagogic hallucinations
- ACh, Orexin deficiency
- Pemoline (Cylert)/Ritalin may relieve
sleep but cause other problems
- Periodic Limb
Movement Disorder
- Involuntary
movement of limbs
- Middle age & elderly
- Tranquilizers sometimes
- REM Behavior Disorder
- Vigorous movement
during REM
- Night Terrors
- Sleep Talking/Walking
- SCN Damage
- Suprachiasmatic Nucleus
- Part of hypothalamus, bilateral
- Source of
endogenous rhythm
- Damage = inconsistent rhythm,
no light/dark synchrony
- Chemical Control
- Adenosine
- Produces Sleepiness
- Caffeine inhibits
- Prostoglandins
- Promotes Sleep
- Inhibits Hypothalamus
cells that + arousal
- Basal Forebrain &
Hypothalamus
- Promotes sleep, release GABA
- Prolonged wakefulness
if damaged
- Anesthesia increases
GABA receptors
- Function of Sleep
- Repair & Restoration
- Repair itself after exertions of the day
- Evolutionary
- Sleep conserves energy to search for
food & keep safe from predators
- Brain Structures of
Wakefulness & Arousal
- Reticular
Formation
- Medulla >
Forebrain
- Lesions =
v arousal
- NE
- Pontomesencephalon
- Stimulation = + arousal
- Locus
Coeruleus
- In pons
- Important for info
storage (hippocampus)
- Mostly inactive
during sleep (why
we forget dreams)
- Basal
Forebrain
& Axons
- To thalamus &
cerebral cortex
- + Arousal
- Damage =
Alzheimers
- ACh
- Hypothalamus
- Stimulates arousal w histamine