Brain and Behavior CH 8 - Wakefulness and Sleep

Endogenous circannual rhythm:

An internal calendarwhich prepares a species for annual seasonal changes.

Endogenous circadian rhythm:

An internal rhythm (clock), which lasts about a day, regulates the times for wakefulness and for sleepiness in 24-h cycle.

Your ___________ rhythm is normally set as the pattern that you always fall asleep at night and wake up in the morning.

circadian

Your circadian is set and reset strongly by the _____

sun

sun light is the:

primary "zeitgeber"

Traveling west "phase-________" our circadian rhythms;

delays

Traveling east "phase-________" our circadian rhythms.

advances

What is one of the reasons why night shift workers never feel properly rested?

their body temperature continues to peak when they are sleeping in the day instead of while they are working at night.

How does the body generate a circadian rhythm

The suprachiasmatic nucleus (SCN);

Genes (Per and Tim)

Levels of melatonin released

The SCN is where?

a part of the hypothalamus

The SCN is the main control center of:

circadian rhythms of sleep and temperature

The neurons of the SCN generate impulses according to lightness / darkness and set a circadian rhythm through the:

retinohypothalamic path

The retinohypothalamic path comes from a special population of ganglion cells that have their own photopigment called:

melanopsin.

The gene 'period' produce proteins called:

PER

The gene 'timeless' produce proteins called:

TIM

Early in the morning concentration of both Per and Tim are ____ and they __________ during the day;

low

increase

During the night the Per and Tim are high, which __________ ____________to inhibit mRNAs that leads to stop producing the proteins.

negatively feedback

The pineal gland secretes:

melatonin

Melatonin secretion usually begins when?

2-3 h before bedtime.

Sleep is an ________ physiological process

active

Coma:

extended period of unconsciousness

coma brain activity:

fairly steady

Response to stimuli during a coma

little (or no) response to any strengths of stimuli,

do you have a sleep cycle during a coma?

no

Vegetative state:

A coma-like state characterized by open eyes and the appearance of wakefulness.

Do you have a sleep cycle during a vegetative state?

Yes

Minimally conscious state:

The stage higher than a vegetative state marked by occasional brief periods of purposeful action and limited speech comprehension.

Brain death:

no sign of brain activity and no response to any stimulus.

The EEG records:

gross electrical potentials in an area of the brain

A polysomnograph (a specific chart recorder) is a combination of:

EEG and eye-movement records

Alpha (α-) waves have a frequency of about ___-___ brain waves per second (Hz)

8-12

Which waves are typical of a relaxed state of consciousness?

Alpha

Which is the stage when sleep has just begun?

Stage 1

Stage 2 sleep is characterized by the presence of:

Sleep Spindles

K-Complex

Sleep spindles: ____-____-Hz waves during a burst (short-lasting high frequency) that lasts at least half a second.

12-14

K-complex:

sharp high-amplitude negative wave followed by a smaller, slower positive wave.

Stage __ and stage __ together constitute slow wave sleep (SWS)

3 & 4

slow wave sleep (SWS) has what type of neuronal activity?

highly synchronized

Why is REM sleep called paradoxical sleep?

It is deep sleep in some ways and light in others

What does REM stand for?

rapid eye movement

During paradoxical (or REM) sleep, the EEG show:

irregular, low-voltage fast waves that indicate increased neuronal activity

the postural muscles of the body, including those that support the head, are:

more relaxed during REM than in other stages

Sleep Cycle:

1,2,3,4,3,2,REM (90 minutes long)

Which sleep stages predominate early night?

3 and 4

toward morning, stages __ and __ grow shorter or even do not occur and ____ grows longer, predominant.

3

4

REM

Reticular formation (neuronal network): What part of the brain to where?

The reticular formation is a part of the midbrain that extends from the medulla to the forebrain and one of the functions is responsible for arousal.

Some neurons of the reticular formation have axons ________ into the brain, and some have axons __________ into the spinal cord.

ascending

descending

__________ axons are well suited to regulate arousal.

Ascending

pontomesencephalon

A complex network connected the pons and midbrain in the reticular formation

pontomesencephalon is located where?

midbrain

pontomesencephalon contributes to?

cortical arousal

Axons from the pontomesencephalon extend to the hypothalamus, thalamus, and basal forebrain. These axons relate what?

ACh

Glu

Norepinephrine neurons in the locus coeruleus do what?

increase wakefulness and vigilance.

Histaminergic neurons in the hypothalamus produce what?

widespread excitatory effects throughout the brain

Orexin

produces the ability to stay awake

Where is orexin produced?

hypothalamus

The basal forebrain releases what?

ACh

GABA

he SCN modulates the amount of released ______ from the basal forebrain to set and reset the circadian cycle.

GABA

Sleep is associated with:

actively inhibiting the brain activity by GABA

Studies suggest that REM is initiated from the _____

pons

During REM, activity in which brain areas become decreased?

V1

Motor Cortex

Dorsolateral Prefrontal Cortex

REM sleep is associated with a distinctive pattern of high-amplitude electrical potentials known as:

PGO (pons-geniculate-occipital) waves

ACh is involved in both:

Wakefulness and REM Sleep

REM sleep depends on both ________________ and ______________ activity for its onset and continuation.

acetylcholine (ACh)

serotonin (5-HT)

______ triggers REM; _______ and ____________ block REM.

ACh

5-HT (serotonin)

norepinephrine

Ordinarily, people fall asleep while their body temperature is _________ and awaken while it is __________

declining

rising

Someone whose rhythm is phase-delayed has trouble with what? and why?

falling asleep at the usual time, as if the hypothalamus thinks it is not late enough.

Someone whose rhythm is phase-advanced has trouble with what?

falls asleep easily but awakens early

Onset insomnia

Trouble falling asleep (phase-delayed).

Maintenance insomnia:

Waking up frequently during the night after falling asleep

Termination insomnia

Waking up too early and can not go back to sleep (phase-advanced).

Sleep apnea:

the inability to breathe for a prolonged period of time while sleeping.

Sleep Apnea is most commonly seen in what demographic?

Middle-aged obese men

How to help sleep apnea

CPAP Mask - Continuous Positive Airway Pressuree

Narcolepsy:

frequent unexpected attacks of sleepiness during the daytime.

cataplexy

attack of muscle weakness while awake

hypnagogic hallucination

dream-like experiences occurring at the onset of sleep

Narcolepsy is due to what occurring during the daytime?

REM

Periodic limb movement disorder:

Repeated involuntary movements of the legs and arms that can cause insomnia. The limb movements occur mostly during Non-REM sleep.

Sleep is defined behaviorally:

normal suspension of consciousness;

Sleep is defined electrophysiologically:

using the EEG recordings by specific brain wave (wave storm) criteria.

memory consolidation:

if people learn something and then go to sleep (or even take a nap), their memory is often improved beyond what it was before the sleep.

Memory consolidation is done via some physiological ways:

Replays

Sleep Spindles

Increased Contrast

about ___-_____ of sleep time is spent in REM,

one-fifth

Two theories for why we go into REM:

1. Memory Consolidation

2. Shaking the eyes to provide sufficient oxygen to the corneas

The activation-synthesis hypothesis

A dream is usually a story "synthesized" by the cortex that is initiated by the PGO waves.

The clinico-anatomical hypothesis:

suggests that dreams are similar to thinking, just under unusual circumstances.