43. Consciousness and Sleep

what is wakeful consciousness characterized by?

alertness, attentiveness

what is sleep characterized by?

muscle relaxation, periods of fast and slow brain waves, unawareness of external stimuli but can be aroused

what is unconciousness characterized by?

lack of awareness of external stimuli and hard to arouse

T/F: wakefulness and sleep are actively generated brain states

true

________ rhythm is a cycle of wakefulness vs sleep per 24 hours

circadian

dirunal

active during the day

nocturnal

active at night

crepuscular

active at dawn and dusk

_______ rhythm is cycles greater than 24 hours during wakefulness and sleep stages

ultradian

what are the 2 basic sleep states?

REM and non-REM

REM sleep

Rapid eye movement,

paradoxical sleep

non-REM sleep

slow wave sleep (SWS)

What is the typical progression of sleep?

start with SWS to REM then if aroused back to SWS and then REM

*stage 4 waves are the most restorative

How do EEG waves differ between wake, NREM sleep and REM sleep?

while falling asleep EEG rhythms get slower and higher in amplitude until reaching NREM sleep.

REM and wake look similar on EEG

circadian rhythm is synchronized to ___-____ photoperiod

day night

what is the input and to where for the sleep wake cycle?

light via retinal input to suprachiasmatic nucleus in hypothalamus

T/F: light input is only important to shift circadian rhythm

true

light induced activation of the SCN prevents production of ___________ by the pineal gland

melatonin

what are the transcription factors of the sleep wake cycle?

Clock and Bmal1

what are the transcription repressors of the sleep wake cycle?

CRY and PER

During daytime ________ and ___________ help transcribe DNA to produce what proteins?

Clock and Bmal1

CRY and PER

During nighttime ________ and ________ enter the nucleus and repress transcription of DNA necessary for production of more of these proteins

CRY and PER

it is the interplay of transcription and repression that create a cycle called what?

circadian arousal drive

what builds up during the day?

what is an example?

what do they act on?

somnogens

adenosine (byproduct of ATP)

adenosine 2a receptors

what is the purpose of somnogens such as adenosine?

reduce wakefulness and induce sleepiness

A2a receptors can be ____________ on wake active neurons found where?

inhibitory

basal forebrain

A2a receptors can be __________ on sleep promoting neurons found where?

excitatory

ventrolateral preoptic nucleus

when are adenosine levels highest?

in the evening

what is an example of something that can block A2a receptors? hint: keeps you awake

caffeine

There is a 2 process model for sleep generation. It means that sleep is most likely when _________ ____________ is highest and when _______ ________ is lowest

sleep pressure

wake drive

what are the important NT of wakefulness?

Ach

glutamate

NE

dopamine

which NT act on PPT nucleus?

Ach and glut

which NT act on PB nucleus?

glut

which NT act on LC nucleus?

NE

which NT act on VTA nucleus during wakefulness?

DA

which NT act on basal forebrain?

ach and gaba

Which neurons help maintain waking state by activating other wake centers?

orexin neurons

What are the main NT in NREM sleep?

GABA

Galanin

NOS

Which NT acts on VLPO nucleus?

GABA and galanin

which NT acts on PZ nucleus?

GABA

which NT acts on VTA during NREM?

GABA

orexin stabilizes sleep and wake centers explain.

orexin stimulates wake centers which inhibit sleeps centers during awake period

however orexin is inhibited along with wake centers during sleep period by sleep centers

THERE IS NO INBETWEEN

what are the main NT of REM sleep?

glut

Ach

MCH

which NT acts on SLD nucelus?

glut

which NT acts on lateral hypothalamus?

MCH

During REM sleep the SLD nucleus activates ventromedial medulla neurons and premotor neurons to (activate/inhibit) spinal motor neurons. Why is this important?

inhibit

prevent info from motor cortex while dreaming

Narcolepsy

excessive sleepiness

cataplexy

stimulus induced sudden loss of muscle tone

narcolepsy with cataplexy can be inherited or sporadic. Explain how

inherited in dogs due to mutation of orexin receptors and sporadic form due to loss of orexin neurons

What happens during REM sleep behavior disorder? aka RBD

lack of inhibition of spinal motor neurons during REM sleep = acting out dreams, may be confused with seizures

altered consciousness