28 Sleep

Question 1

What distinguishes sleep from other brain states (behaviorally and electrophysiologically)

Answer 1

Quiescence, descreased awareness of external environment, rapidly reversible, characteristic brain wave patterns

Question 2

What three types of measurements are taken during sleep studies?

Answer 2

electroencephalogram (brain waves), electromyogram (muscle tension) and electrooculogram (eye movements)

Question 3

Describe features of a electroencephalogram of the following states: eyes closed/resting, NREM Stage N1, NREM stage N2, NREM Stage N3, REM sleep

Answer 3

resting (alpha rhythms), N1 (theta waves) slowing and synchronization of waves, N2 (sleep spindles produced by the thalamic reticular nuclei) N3 (greater amplitude waves) and REM (waves similar to awake state)

Question 4

What is the proportion of NREM slow wave sleep to REM sleep as the night wears on for a normal sleeper.

Answer 4

SWA is greatest at the first part of the evening where REM is increased in the later portion of the night

Question 5

What are some of the physiological effects of NREM sleep?

Answer 5

increased parasympathetic activity, decreased HR, CO and BP, decrease ventilation, decreased hypoxic and hypercapnic ventilatory response, decrease in EMG activity

Question 6

What are the physiological effects of REM sleep?

Answer 6

increase in sympathetic activity (phasic REM), irregular breathing pattern, decreased in thermoregulatory reps one, paralysis of skeletal muscle, extra ocular movements, dreaming

Question 7

Contrast a legion of the anterior hypothalamus with a lesion at the junction between brainstem and forebrain as they related to sleep.

Answer 7

lesion of the anterior hypothalamus will lead to profound insomnia; lesion between the brainstem and forebrain lead to profound sleepiness (lesion between lead to narcolepsy)

Question 8

Contrast the two major pathways of the ascending arousal system.

Answer 8

the dorsal branch uses Ach. as it neurotransmitter and ascends through the thalamus, the ventral branch uses monoamines as its signaling molecule and travels bypasses the thalamus

Question 9

How does a lesion between the forebrain and the brainstem affect the arousal system?

Answer 9

it disconnects the ascending arousal system, causing profound sleepiness

Question 10

How does the ventro lateral pre optic area promote sleep?

Answer 10

VLPO inhibits the ascending arousal system which promotes sleep (a lesion to the anterior hypothalamus damages VLPO causing loss of inhibition and insomnia

Question 11

Orexin neurons in the hypothalamus are important to sleep how?

Answer 11

orexin neurons in the hypothalamus are important for stabilizing sleep-wake transitions (damage of these neurons can lead to narcolepsy with cataplexy)

Question 12

What are symptoms of narcolepsy?

Answer 12

excessive daytime sleepiness, sleep paralysis, hypnagogic/hypnopomic imagery (dream mentation during wakefulness), cataplexy (loss of muscle tone due to emotional situation) and automatic behaviors

Question 13

Which nuclei are important in NREM sleep?

Answer 13

thalamic reticular nucleus, and basal forebrain

Question 14

What is the basal forebrain play in sleep?

Answer 14

build up of adenosine in the basal forebrain causes increase of slow waves (increased during sleep deprivation also)

Question 15

What thalamic nucleus is responsible for sleep spindles.

Answer 15

thalamic reticular nucleus

Question 16

How can PPT (peduculopontine) and LDT(laterodorosal tegmental) be active in both wake and REM sleep states?

Answer 16

activation in different states is due to cell types with differential sensitivity to serotonergic and noradrenergic input

Question 17

T/F Normally REM sleep is associated with muscle tone comparable to to alert brain states.

Answer 17

false, normally, REM sleep is associated with atonia due to net inhibition of spinal motor neurons (disfunction of this system can clear to REM-behavior disorders

Question 18

Inhibition by what nuclei are important to inhibit REM-On LDT/PPT neurons.

Answer 18

the locus cereuleus and the dorsal raphe both promote wakefulness by inhibiting REM-on nuclei

Question 19

What are the effects of antidepressants on REM sleep?

Answer 19

they increase the latency of REM sleep and the decrease REM total time

Question 20

How do wakefulness drive (sleep debt) and alerting signal (circadian rhythm) interact to produce periods of wakefulness and sleep?

Answer 20

wakefulness drive decreases throughout the day alerting signal increases until the onset of melatonin at the end of the day

Question 21

Describe the sleep of someone who is sleep deprivation once that person succumbs to sleep

Answer 21

they will sleep longer and their slow wave activity will be increased

Question 22

Name 3 general symptoms that circadian rhythms have an effective on.

Answer 22

brain function, autonomic tone and hormone release

Question 23

Which nucleus is considered the master biological clock?

Answer 23

the suprachiasmatic nucleus (hypothalamus): promotes wake and suppresses REM/ sleep

Question 24

Circadian timing will directly regulate what functions

Answer 24

plasma melatonin, autonomic output controlling body temperature and adrenal gland secretion of cortisol

Question 25

Describe the steps in the round-about pathway of melatonin secretion.

Answer 25

photic input to the SCN, which sends signal via the intermediolateral cell column in the upper thoracic spinal cord. ICC signals to superior cervical ganglion which effects the pineal gland to secrete melatonin

Question 26

Photic input to the SCN is via what types of cells in the retina

Answer 26

melanopsin containing cells (light inhibits production of melatonin)