aleep and consciousness Flashcards
(28 cards)
Function of general sleep
1) RESTORATIVE HYPOTHESIS (REGENERATION)
2) ADAPTIVE REACTION
REGENERATION)
in animal expts: may cause death, loss of weight and body care
after deprivation: SWS4 and REM is made up
effect of physical effort? sleep pattern of patients confined to bed
ADAPTIVE REACTION
avoidance of predators
REM – effect of meaningful stimuli – chance to survive
FUNCTIONS OF REM
developmental hypothesis: newborns of predators (and man) need more
in learning and memory: selective REM deprivation slows down learning, memory functions are impaired
4 phases and REM
o Frequency gets lower, amplitude increases
o Just before sleep still alpha waves, phase 2 sleep spindles, 3 and 4 deep relaxation (slow wave)
o Tonic REM with phasic activity
o 90 minute cycles throughout the night, about 7 hours of sleep, 3-4 REM phases → differs
Neuronal Regulation of Sleep in Wakeefulness → producing area between two levels of transaction (EEG)
o Cerveau isolé → permanent sleep (all raphe are cut from brain)
o Encephale isolé → unchanged sleep pattern (at least some raphe are still at brain)
- ARAS
(Ascending reticular activating system and Raphe system
Neuronal Regulation of Sleep in Activation of specific neural circuits triggers sleep and wakefulness
o Cholinergic neurons of ARAS → awaken
o Slow electrical stimulation of thalamus → fall asleep
o Posterior hypothalamus → arousal (ergotrop)
o Anterior hypothalamus → sleep (trophotrop)
- REM → ACh neurons become active in pons
o Loss of muscle tone
Inhibitory neuron in medulla → to motor neuron and muscle
o Eye movements, PGO waves → Pons → lateral geniculate → occipital cortex
Each wave is synchronized with an eye movement
o Desynchronized EEG
o Hippocampal theta rythm
- Biochemical regulation of SWS
o Glycogen metabolism → adenosine is released (inhibitory neuromodelator) → induces SWS
Caffeine is adenosine inhibitor
o Following sleep deprivation
S-factor (muramil peptides)
DSIP (deep sleep inducing factor)
o Sleep proting substance (SPS, uridin)
o Stimulation of basal forebrain cholinergic system causes ACh increase in cortex and concomitant EEG desynchronization
- Biochemical regulation of REM
o Noradrenergic system → locus coeruleus (medulla)
o Serotinergic system → raphe nuclei
o Both stop during REM, increasing activity of cholinergic system (pons) during REM
- Sleep and thermoregulation
o Part of basal forebrain is center (preoptic part of hypothalamus) of thermoregulation → its warming causes SWS
Warming face or body increases SWS
During SWS brain temperature decreases
During REM temperature of brain increases
Sleep disorders
- Insomnia
- Narcolepsy
Sleep attack
Cataplexy
Sleep paralysis
Hypnagogic hallucinations - Somnambulism
- Narcolepsy
→ disorder of REM
- sleep attack
normal sleep for a few minutes
- cataplexy
loss of muscle tone durink awake state
- Sleep paralysis
before going to sleep or before waking up.
- Hypnagogic hallucinations
frightning
- Somnambulism
combined sleep and wakefulness
Circadian rhythms
Biological clock
- Retinohypothalamic pathway
o Nucleus suprachiasmaticus (in hypothalamus) → pineal glad (melatonin).
- SCN transplanted into other brain causes change of circadian rhythm → the secretion of the hypothalamic hormones is also changed
ATTENTION passive and active
orientating reaction (reflexes) vs selective attention
- Skinner-Yingling model
o Frontal cortex → modality specific inhibition in NR – relevant channel activated o MRF (mesencephalic reticular formation)→ result of inhibition of NR
Consciousness criteria
correct awareness of self and enviroment and space
continuity and clarity
