Sleep and Circadian Rhythms Flashcards
The definition of wakefulness is …
an aspect of quantitative consciousness
The definition of arousal is ….
transition from sleep to wakefulness
Somnolence is a disorder where one will …
keep falling asleep
What is a common tool in clinical medicine used to assess the degree of consciousness of a person
Glasgow Coma Scale
What is the outcome of cerveau isolé, transection at the ponto-mesencephal level
persistent sleep, similar to a coma
The VLPO (Ventrolateral preoccipital nucleus) of the hypothalamus releases what neurotransmitter?
GABA
The LH (lateral hypothalamus) releases what neurotransmitter?
Orexin
The TMN (tuberomammillary nucleus) releases what neurotransmitter?
Histamine
The Raphé-Kern released what neurotransmitter?
Serotonin (5-HT)
The LDT, BV (dorsal tegmentum, basal forebrain) release what NT?
Acetylcholin (ACh)
The LC (locus coeruleus) releases what NT?
Noradrenalin
The VTA (ventral tegmental area) releases what NT?
Dopamine (DA)
What structure in the brain co-ordinates the activity of the brainstem nuclei and is crucial to induce sleep
Hypothalamus
In what 3 dimensions is EEG measured?
Temporal, topographical and frequency
Alpha-EEG activity is suppressed while a person eyes are open? T or F
True
The entire suppression of REM and SWS can have detrimental effects on health. T or F?
T
The quality of sleep one gets is defined by the amount of stage 4 sleep they get? T or F?
F. By the amount of SWS and REM sleep
The dissociation of two states of vigilance in one single person where the persons motor system is in a state of REM sleep, but they are awake is known as what?
Cataplexic attack - this is a defining symptom of Narcolepsy
What are the 3 types of narcolepsy?
- Narcolepsy with cataplexy
- Narcolepsy without cataplexy
- Symptomatic narcolepsy
What is cataplectic status?
Complete inability to move to the capacity of breathing. Occurs when you withdraw anti-cataplexic medicine too early.
Orexin is exclusively produced in the hypothalamus and has an exclusive connection with the LC, Raphe, VTA and LDT which are involved in the induction of sleep and the maintenance of wakefulness. T or F?
T
About 50,000 hypocretin-producing neurons in the ventromedial hypothalamus? T or F?
F in the posteriolateral hypothalamus
What systems are regulated through the LHA?
Behavioural, emotional, sleep/wakefulness and motor systems
What is the only NT system that induces sleep?
GABA
The human internal clock has a period of 24 hrs. T or F?
F
What hormone rises while we sleep and peaks around the time of waking?
Cortisol
Melatonin is a sleep hormone?
No. Its a DARK hormone
What is chronotheraphy?
It is when you make use of the many rhythms in the body and change the medication to accommodate for this.
Who was the 1st person to come up with the idea that humans have a biological clock and tested this by using WW2 bunkers?
Jurgen Aschhoff
Circadian rhythm is endogenous, it is self-sustained and it is not 24 hours. T or F?
T
What are the fundamental properties of circadian clock?
- Circadian clocks are endogenous, self-sustained oscillators
- The free-running period tau is close to but not exactly 24 hours
- The free-running periods are temperature-compensated
- Rhythmic environmental stimuli entrain (sync) circadian clocks
Where is the internal clock located?
Suprachiasmatic Nucleus (SCN)
How do we know that the SCN is the master clock?
- SCN lesions result in loss of overt circadian rhythms
- Transplantation of fetal SCN tissue in an SCN-lesioned arrhythmic host restores locomotor activity rhythms– do a transplant from a hamster that has a shorter cycle and a normal hamster and see if there is a difference when the transplant is done. First you should breed the hamsters. This allows you to see if this behaviour is genetically transferred.
- Genotype of the donor SCN determines circadian period of the grafted host
- SCN explants and even dispersed SCN neurons show self-sustained circadian oscillations in neuronal spiking activity in vitro
- SCN is linked anatomically to the retina via the retinohypothalamic tract (RHT) – neuronal connection, one axon is coming from the retina directly to the SCN, it uses the optic nerve and instead of ending in the visual cortex some of these neurons directly project to neurons in the SCN.
Clock proteins inhibit their own production to cause an oscillatory behavior? T or F?
T
Clock and Bmal1 form a heterodimer and then bind to the f-box and this drives the transcription of Per1-2 and Cry1-2. They are translated in the cytoplasm and they form huge complexes and are PTM. It takes a long time before a critical level of these molecules is produced and then they go back into the nucleus and inhibit the transcription of the clock genes.
What happens if you KO B-mal in mice?
The mice have no rhythm at all and they also suffer from early ageing.
What percentage of genes have rhythmic properties?
10-20%
Can a gene be rhythmic in one body part but constant in another area?
Yup
Does light reset the circadian clock?
Yes by the induction of period genes
Define Entrainment
Synchronization of the endogenous oscillator to the light/dark cycle of the environment.
What cells are the most efficient at resetting the clock?
Melanopsin containing retinal ganglion cells
In the model of the timing of sleep what two processes regulate the timing of sleep?
Circadian process and homeostatic process
