Chapter 8 - Wakefulness & Sleep Flashcards by Elisa Soto

In humans, the sun, alarm clocks, and eating (feedings) are all ________ that help maintain endogenous ________ rhythms.

zeitgerbers; circadian

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The daily pattern of human temperature is highest around ____ hours from sleep time, and lowest around _____ hours into sleep.

6 hours; 2 hours.

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The purpose of the circadian rhythm is to?

To keep our internal workings in phase with the outside world.

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A stimulus that resets circadian rhythms is? The most potent for land animals is? For animals at sea?

A Zeitgerber; sunlight; tides.

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Light intensity, temperature, food availability, and social interactions are all examples of stimuli known as _________.

Zeitgerbers

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Due to alternating between 45’ of light and 45’ of darkness, astronaut often experience? What other group of scientists might experience this?

Depression and cognitive impairment; scientists in the antarctic.

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In Germany, the east side experiences sunrise ~30’ earlier than their western counterparts. What does this due to their circadian rhythms?

People on the east tend to go to bed earlier and wake earlier.

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How might blind people set their circadian rhythms?

Noise, temperature, meals, and activity

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Humans vs. squirrels - what’s the length of the biological clock for each?

Humans slightly >24hrs; squirrels slightly <24hrs.

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Regarding jet lag, which direction is easiest to travel from/to, and why?

From east to west because it’s easier to stay up later than to try to go to sleep earlier (circadian rhythm is slightly >24hrs).

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Regarding jet lag, traveling east causes a ____-_____ in our circadian rhythm while traveling west causes a ____-_____. Which is ‘easier’?

phase-advance; phase-delay. Phase-delay (traveling west) is easier - it’s harder to go to bed earlier.

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Jet lag can case elevations in what hormone? Prolonged exposure (as evidenced in flight attendants) can damage what?

Elevates cortisol levels; damage to the hippocampus which causes memory impairments.

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Circadian rhythms in all animals change as a function of their _____. Why might this be?

Age; staying up later during late adolescence to early adulthood may be due to sex hormones and increased mating.

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The main control center of the circadian rhythms for sleep and body temperature is the ____ ____? Where is it located?

surprachiasmatic nucleus (SCN); located above the optic chiasm

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Circadian rhythms generated by the SCN are controlled by? What is the significance of a single SCN cell in a culture?

genetics; it will keep the circadian rhythm all on its own.

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SCN cells transplanted from a mutated mouse with a 20 hr rhythm to a normal mouse will do what? How about transplanting the reverse?

A normal mouse will have the circadian rhythm of the donor SCN cells; a mouse with the mutation will have the rhythm of the healthy donor mouse.

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The _____ path of the optic nerve alters the SCN’s settings due to the presence of _______ in the retinal ganglion cells of this path.

retinohypothalamic path; melanopsin

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Mice that have a genetic defect which renders them nearly blind can maintain a circadian rhythm due to?

The presence of the ganglion cells with melanopsin and the the retinohypothalamic path.

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Blind mole rats can see light because of the presence of the _________ path, but they need ____, ____-____ light in order to activate.

retinohypothalamic path; sustained, blue-wave light.

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What condition stimulates the ganglions of the retinohypothalamic path?

darkness/dim light

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Animal studies from this animal revealed several genes responsible for circadian rhythms, including the period and timeless genes.

Drosophila

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The production of these two circadian proteins (name them) is controlled by what? What causes production, and when is production increased? Decreased?

An automatic feedback loop controls the production of PER and TIM proteins. mRNA is responsible for production, and it increases throughout the day. Once the concentration of PER and TIM are high, mRNA is inhibited.

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How are PER and TIM concentrations reduced, and why are they reduced?

Light activates chemicals that break them down which helps keep synch with the environment.

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The SCN regulates waking and sleeping by _____ activity levels in other areas of the brain including the _____ gland - an endocrine gland posterior to the thalamus that secretes ______.

controlling; pineal; melatonin.

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_______ is a hormone secreted by animals that helps to induce sleep in diurnal animals and wakefulness in nocturnal animals.

Melatonin

Sleep is a state that the brain passively/actively produces.

Actively

A coma is categorized by extended unconsciousness and _____ brain activity with ______ response to stimuli.

low; reduced

A vegetative state is categorized by alternations between _____ and moderate _____ with/without purposeful action. Also, they respond to stimuli, like pain, by?

sleep and moderate arousal; without. Increased heart rate.

A minimally conscious state is categorized by alternations between _____ and moderate _____ with/without purposeful action.

sleep and moderate arousal; with.

A _______ combines EEG and eye-movement to record various stages of sleep.

polysomnograph

Stage 1 sleep is characterized by ____ ____ at a frequency of 8 - 12 Hz per second.

alpha waves

Alpha waves are characteristic of ________, not wakefulness; and indicates that sleep has just ______.

Relaxation; begun

T or F: In stage 1 sleep, brain activity is less than in relaxed wakefulness and in other sleep stages.

False: brain activity is less than in relaxed wakefulness; however, it is higher than other sleep stages.

This sharp brain wave is associated with temporary inhibition of neuronal firing and is usually accompanied by sleep spindles in stage two.

K-complex

During stage 2 sleep, a ____ _____ is a series of 12-14 Hz waves occurring in burst that last at least 1/2 second resulting from oscillations between cells in the thalamus and ____.

Sleep spindle; cortex

Sleep spindles increase in number after new _____ and have a positive/negaive correlation with improvements of certain types of memory.

learning; positive

Sleep spindles are related to memory ________.

consolidation

There is a > 0.7 correlation between _____ ______ and IQ (nonverbal).

sleep spindle

K-complexes have been suggested to _____ sleep and also contribute to memory ______.

protect; consolidation

Do K-complexes arise spontaneously, or are they evoked? Explain.

Both; they respond to internal and external stimuli which is suggestive of them being a mechanism for sleep protection.

K-complexes induce a state that allows for cortical firing "_____" in a systematic order so that memory engrams (changes to the brains wiring) can be "repeatedly practiced and thus ______".

"reboots"; consolidated.

Stages 3 & 4 are dominated by ___, ____-amplitude waves and decreased breathing, heartbeat, and brain activity; this is aptly named ____-____ sleep.

slow; large-; slow-wave sleep

Slow waves in polysomnographs indicate that neuronal activity is _____ synchronized.

highly.

During ___-wave sleep, the _____ (and therefore, the _____ _____ nuclei) are hyperpolarized, so sensory input to the cerebral cortex is greatly ______.

slow; thalamus; thalamic relay; reduced.

REM sleep is AKA as ______ sleep because heart rate, blood pressure, and breathing are more _______ than in stages 2 - 4; however, ________ muscles are more relaxed than in other stages.

paradoxical; variable; postural

EEG shows irregular ___, low-voltage ___, and fast ___ of increased neuronal activity associated with ______ sleep.

waves; waves; waves; REM

The typical sleep cycle starts with ____ waves of stage 1; _____ spindles and ___-complexes of stage 2; ___-____ sleep of stages 3 and; back to stage 2, and irregular, low-voltage, fast waves of ____ sleep.

alpha; sleep; K-; slow-wave; REM

The ______ formation is a structure that selectively increases arousal and attention in various forebrain areas; and it extends from the _____ to the forebrain.

reticular; medulla

The ________ part of the reticular formation contributes to cortical arousal due to widespread ______ effects (release of _____ and ______) throughout the cortex. Its axons extend to the ______, ______ and _____ forebrain.

pontomesencephalon; excitatory; acetylcholine and glutamate. thalamus, hypothalamus, and basal

The _____ (hindbrain) serves as a message station between several areas of the brain.

Pons

The _____ ______ structure within the pons is usually inactive, but will emit burst of impulses in response to _____ events, esp ______ arousal. Its output _____ activity of the most active neurons and ____ the activity of less active neurons, a phenomenon known as "____"; and it releases the NT _______. Surprisingly, it suppresses ______ sleep.

locus coeruleus; meaningful; emotional. increases; decreases; "gain"; norepinephrine REM

Parts of the hypothalamus release _______ to produce widespread excitatory effects throughout the brain. Many anti-_____ drugs counteract this neurotransmitter - but only if they cross the ____-_____ barrier.

histamine; histamine; blood-brain

Parts of the hypothalamus releases a peptide neurotransmitter called _____ (aka hypocretin). The axons releasing this NT extend to the ____ forebrain and many other areas to enhance wakefulness - but it does not _____ waking up!

orexin; basal; stimulate

A lack of _____ can cause _____: a sleep disorder where the person falls asleep throughout the waking period - even in the middle of activities that normally cause arousal.

orexin; narcolepsy

_____; a neuroscientific technique that uses a GMO virus to insert _____-sensitive proteins into the membrane of a given neuron, can be used to study narcolepsy or other sleep disorders. The researcher can stimulate activity in targeted neurons by shining a ____ within the brain.

Optogenetics; light-sensitive; light

Which part of the brain releases GABA to promote sleep? What NT does it release to promote wakefulness? What is curious about the NT it releases during wakefulness; in other words, when else is it released?

basal forebrain acetylcholine It releases acetylcholine to induce REM during sleep.

When neurons of the thalamus do fire during sleep, they fire in _____ bursts, yielding ____-amplitude waves characteristic of ___-____ sleep.

synchronous; high-amplitude; slow-wave

When GABA is released and weakening connectivity, and when stimuli is presented, the signal is not _____, so there's no _____ awareness of the stimulus.

spread; conscious

GABA is important during sleep because it ____ stimulation of neurons, and because it decreases _____ and ____ rate to conserve energy.

decreases; temperature and metabolic rate

Sleep can be ____ within the brain because it depends on ______-mediated inhibition (which can be restricted to select areas of the brain).

local; GABA

Sleepwalkers do not have the NT _____ released to their ____ cortex.

GABA; motor

During ____ dreaming, someone is aware of being asleep and dreaming. This enables some control over ____ and ____ movements.

lucid; dreaming; eye

Sleep paralysis occurs when cells in the ___ and ___ inhibit spinal neurons, but the pons remains in REM. Cats with damage to the pons will awkwardly ______ around during sleep.

pons; medulla move

REM sleep is associated with distinctive patterns of _____-amplitude electrical potentials knowns as ____ waves (which stands for the ____, _____ and ______ lobe). While in REM, activity increases in the ____ which triggers the onset of REM sleep and triggers the limbic system.

high; PGO waves; pons, geniculate, occipital. pons

REM is regulated by the pons, medulla, and by the NTs _____ (activates REM) and ______ (interrupts REM). The latter interrupts REM - HOWEVER, no cognitive _____ have been noted from people on SSRIs or SARIs.

acetylcholine; serotonin; deficits

_____ is a sleep disorder of inadequate sleep. Causes include ___ lag, blue ____, diet, stress, temperature, and ___ disease

Insomnia; jet; light; Parkinson's

Some cases of insomnia can be attributed to shifts in ___ rhythms. For example, people who's rhythms are phase-___ will have too high a body temp before bed, and people who are phase-___ will be too warm before waking hours.

circadian; delayed, advanced.

Causes of sleep ____ include: hormones, ___ of the brain that regulates breathing, _____ (esp middle-aged men), and genetics. They are at increased risk of ____, CVD, and depression; and they loose neurons due to low __.

apnea; aging; obesity. stroke, O2

Narcolepsy relates to deficiencies of what NT? Where is it produced? Some narcoleptics produce enough NT, but they are lacking what? What are the 4 symptoms of Narcolepsy?

Orexin; hypothalamus; receptors (1) Sudden daytime sleepiness; (2) cataplexy (muscle paralysis); (3) hypnogogic hallucinations, (4) sleep paralysis

Huntington's disease can cause _____ due to damage to the hypothalamic cells that produce ______.

narcolepsy; orexin

What is periodic limb movement disorder? Who does it mostly affect, and at what sleep stage?

Involuntary movement of the limbs during sleep that mostly affects middle- to older-aged men, and usually occurs during NREM

Unlike periodic limb movement disorder, ____ behavior disorder is vigorous movement during _____ (dreaming about defending themselves) and may be due to ___ (NT) deficiency.

REM; REM; GABA

____ _____ are intense anxiety from which a person wakes from NREM screaming.

night terror

Sleepwalking runs in _____, and usually occurs during ___. Sleep deprivation and ____ are commonly reported by sleepwalkers.

family; SWS; stress

Functions of sleep include ___ balance, ____ immunity, rest ____, perform ____ maintenance, reorganize ____ to strengthen memories.

hormonal, strengthen, muscles, cellular (neuron, muscle, etc.), synapses

The primary reason for sleep is to conserve ___ by ___ the body temp, ___ muscle activity.

energy; lowering; reducing

During hibernation, neurons loose _____ which enables near invulnerability. The smaller an animal is, the ___ it hibernates.

dendrites deeper

How much do animals in caves sleep? How are animals near the poles similar? How might sleep differ for some animals who are predators or have excellent defense mechanisms (armadillo)?

Almost not at all. During summer when the sun almost never sets, animals like reindeer and penguins barely sleep (or don't). Predators sleep more, defensive sleep more, prey animals sleep less.

Recall is _____ for sounds heard during sleep.

improved

Patterns in the ____ resemble those during learning, but the patterns are more ______ during sleep. Additionally, the amount of _____ activity during sleep correlated highly with improved performance on learned tasks. This is evidence that as the brain replays events, it forms new _____ branches and weeds out weaker connections.

hippocampus; rapid. hippocampal. dendritic

The longer an organism sleeps, the more time is spent in ___. For humans, the most time spent in ___ is during ____ (everything is new).

REM; infancy

One hypothesis about REM sleep is that it helps to _____ memory, but this doesn't explain why SARI's enhance memory. Another hypothesis is that rapid eye movement helps...?

strengthen; oxygenate the corneas.

What evidence indicates that people have an internal clock?

People who live in an atypical 24 hr environment fail to follow that schedule; instead they become wakeful and sleepy based on a normal 24 hr cycle.

Why do people on the eastern edge of a time zone wake earlier than the west side during holidays?

The sun rises earlier and provides evidence that sunshine plays a role in sleep-wake schedules.

Name 2 pieces of evidence that show the SCN maintains its own rhythm.

(1) SCN cells in culture keep their own rhythm; (2) Hamsters w/ transplanted SCNs keep the rhythm of the donor cells.

Blindness due to cortical damage doesn't disrupt circadian rhythms associated with light - how?

As long as the retina is ok, melanopsin-containing ganglions will still transmit to the SCN

Large, slow waves on an EEG indicate what two things?

(1)Low level activity and (2) neural synchronization

During a sleep study, what 2 things can be evaluated to determine if the person's in REM?

(1) eye movement; (2) EEG pattern

Someone who just woke may not make sense, why? 2 reasons.

(1) Not all of the areas of the brain wake at the same time, (2) REM is more prevalent in the hours before waking, and some brain areas may still be in a REM/dream-like state.

How might weakening synapses during sleep help to improve memory?

Weakening synapses that aren't active help the strengthened synapses stand out.