lecture 25: why do we sleep and dream

Question 1

chemical candidate

Answer 1

melatonin secreted from pineal gland
- is sleep caused by a circulating chemical or activity of the brain
but removal of pineal gland does not abolish sleep and some animals sleep 1 hemisphere at a time

Question 2

the RAS in sleep

Answer 2

EEG used to record brain activity of anesthezied cats while stimulating brainstem
discovered cortical EEG transitioned from delta to sustained beta waves when stimulated
in sleeping cats, stimulation woke the cat

Question 3

damage to RAS

Answer 3

produce a coma

- source of waking

Question 4

is sleep active or passive

Answer 4

not a result of lack of sensory input to RAS because if RAS is deafferentiated, animals still maintain regular sleep wake
other brain regions may participate in sleep/wake cycles

Question 5

basal forebrain

Answer 5

cholinergic cells secrete ACh onto neurons to stimulate waking EEG rhythm beta
- associated with alert but immobile behavior (Attention)

Question 6

median raphe nucleus

Answer 6

contains serotonin neurons that project to neocortex and stimulate beta rhythms
- associated with movement

Question 7

peribrachial area

Answer 7

cholingergic nucleus in dorsal brainstem has a role in REM sleep: projects to MPRF
inibitates REM sleep and related behaviors

Question 8

medial pontine reticular formation

Answer 8

cholinergic nucleus in the pons participating in REM sleep
projects to several other brain areas that produce REM related behavior
produces atonia of REM sleep

Question 9

neural control of REM sleep

Answer 9

1. paribrachial area initiates REM sleep by activating MPRF
2. MPRF activates basal forebrain Ach system stimulating waking state EEG
3. MPRF also activates brainstem motor nuclei to initiate eye movements
4. MPRF initiates atonia by activating subcoerular nucleus
5. subC activates magnocellular nucleus of medulla which sends GABAergic and glycenergic projections to spinal motor neurons to shut them down

Question 10

insomnia

Answer 10

slow wave sleep disorder resulting in inability to sleep
causes: anxiety, depression, shift work, stress
sleep medications deprive of REM sleep

Question 11

drug dependency insomnia

Answer 11

continuous use of sleeping pills builds up tolerance which leads to increased drug dosages

Question 12

narcolepsy

Answer 12

slow wave sleep disorder where person falls asleep at inapropriate times
short periods of NREM before REM
causes: sleep apnea, loss of orexin producing neurons
cataplexy, hypnogognic hallucinaiton, sleep paralysis

Question 13

REM sleep behaivoral disorder

Answer 13

behave as though they are acting out their dreams
do not experience atonia during REM
- older men
- antidepressants
- neurodegenerative disorders (parkinsons)

Question 14

consciousness

Answer 14

states mix together to produce unusual conditions
sleep events (atonia) can intrude into waking (sleep paralysis)
waking events can intrude into sleeping
- studying sleep may help understand psychiatric and drug induced conditions