Week 9 Flashcards
What is the innate phenomenon that tells birds to fly north in the spring?
Endogenous circannual rhythm
What evidence indicates that humans have an internal biological clock?
Studies of humans that live in light controlled environments demonstrate alertness when they would usually be waking up.
What is circadian rhythm?
Daily body rhythm
What is a zeitgebers?
Stimulus that resets circadian rhythm.
Most obvious one is light.
Why do people at the eastern edge of a time zone awaken earlier than those at the western edge on their weekends and holidays?
The sun rises earlier at the eastern edge than at the western edge. Evidently, the sun controls waking–sleeping schedules even when people follow the same clock time for their work schedule.
How does stress cause damage to the hippocampus?
Stress elevates blood levels of the adrenal hormone cortisol; prolonged elevations of cortisol damage neurons in the hippocampus, a brain area important for memory.
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Is the tendency to stay up later during adolescence culture specific?
No, has been observed in every culture that has been studied.
The same trend occurs in rats, monkeys, and other species.
How might being a morning person or an evening person affect morality?
Morning people are more honest in the morning, evening people are more honest in the even.
How might being an evening person affect schooling?
Evening people do worse at their morning classes, even if they are above average intelligence.
What is the suprachiasmatic nucleus (SCN)?
A part of the hypothalamus.
Provides main control of circadian rhythms.
- How does light reset the biological clock?
- A branch of the optic nerve, the retinohypothalamic path, conveys information about light to the SCN. The
axons comprising that path originate from special ganglion cells that respond to light by themselves, even if they do not receive input from rods or cones.
- People who are blind because of cortical damage can still synchronize
their circadian rhythm to the local pattern of day and
night. Why?
- If the retina is intact, melanopsin-containing ganglion cells can still send
messages to the SCN, resetting its rhythm.
What are the two genes responsible for circadian rhythm?
Period (PER)
Timeless (TIM)
How do people with PER mutations differ from normal?
They have shorter circadian rhythm
- How do the proteins TIM and PER relate to sleepiness in Drosophila?
- The proteins TIM and PER remain low during most of the day and begin to increase toward evening. They reach
high levels at night, promoting sleep. They also feed back to inhibit the genes that produce them, so that their level declines toward morning.
How is the pineal gland related to sleep?
Releases the hormone melatonin. Melatonin is usually released at night about 2-3 hours before sleep and causes drowsiness.
- Workers on certain submarines work 6 hours, relax 6 hours, and then sleep 6 hours. After weeks on this schedule, what happens to their circadian rhythm?
A. It adjusts to produce an 18-hour rhythm.
B. It continues producing the usual 24-hour rhythm.
C. It produces a rhythm intermediate between 18 and 24 hours.
D. It stops producing any rhythm at all.
B. It continues producing the usual 24-hour rhythm.
- Why do people in Antarctica during the winter often find it difficult to work together?
A. Their work schedules keep them so busy that they cannot sleep enough.
B. Their circadian rhythms drift out of phase with one another.
C. After living together in close quarters for so long, they start to irritate one another.
D. They get homesick.
B. Their circadian rhythms drift out of phase with one another.
- For most young adults, what happens to mood as a function of time of day?
A. Mood tends to be most pleasant early in the morning.
B. Mood tends to be most pleasant around noon.
C. Mood tends to be most pleasant in late afternoon or early evening.
D. Mood fluctuates, but on average is about the same for one time as for another.
C. Mood tends to be most pleasant in late afternoon or early evening.
- Why do people in eastern Germany awaken earlier, on average, than those in western Germany?
A. The sun rises earlier in eastern Germany.
B. Eastern Germany is in a different time zone.
C. A gene that inactivates melatonin is more common in eastern Germany.
D. A gene that inactivates melatonin is more common in western Germany.
A. The sun rises earlier in eastern Germany.
- Why do many high school students get worse test grades in the morning than in the afternoon?
A. Most schools schedule the math and science courses mainly in the morning.
B. Teenagers tend to stay up late and awaken late.
C. Many teenagers do not eat a healthy breakfast.
D. Many high schools are not adequately heated during the morning.
B. Teenagers tend to stay up late and awaken late.
- What evidence most strongly indicates that the SCN produces the circadian rhythm itself?
A. Damage to the SCN disrupts the circadian rhythm.
B. SCN cells isolated from the body continue to produce a circadian rhythm.
C. Animals with a faster circadian rhythm have a larger SCN.
D. The SCN increases its activity during wakeful periods and decreases it during sleep.
B. SCN cells isolated from the body continue to produce a circadian rhythm.
- Light can reset the SCN’s rhythm even after damage to all rods and cones. Why?
A. The SCN itself responds to light.
B. The SCN receives input from the pineal gland.
C. The SCN receives input from skin cells that respond to light.
D. The SCN receives input from ganglion cells that respond to light.
D. The SCN receives input from ganglion cells that respond to light.
- If you want to get to sleep on time, what should you avoid?
A. Long-wavelength light late in the evening
B. Short-wavelength light late in the evening
C. Long-wavelength light early in the morning
D. Short-wavelength light early in the morning
B. Short-wavelength light late in the evening
- After the proteins TIM and PER reach a high level during the day, what causes their level to decrease at night?
A. High levels of the proteins inhibit the genes that produce these proteins.
B. The genes that produce these proteins become less active when temperature drops.
C. Rapid production of the proteins depleted the supply of the amino acids needed to make them.
D. Decreased light stimulation decreases excitatory transmission throughout the nervous system.
A. High levels of the proteins inhibit the genes that produce these proteins.
- When is melatonin mostly released?
A. At night, for all species
B. During the day, for all species
C. At night for species active at night; during the day for species active during the day
D. At night for species active during the day; during the day for species active at night
A. At night, for all species
What’s the difference between sleep, coma, vegetative state, minimally conscious state, and brain death?
Sleep
Actively produced by the brain.
Decreased brain activity and response to stimuli
Coma
Extended period of unconsciousness caused by head trauma, stroke, or disease.
Vegetative state
Alternates between periods of sleep and moderate arousal, but even during more aroused state the person shows no awareness of surroundings or purposeful behaviour.
Breathing is regular, and painful stimulus shows autonomic responses.
Minimally conscious state
One stage higher than vegetative; brief periods of purposeful actions and limited amount of speech recognition.
Brain death
No sign of brain activity and no response to any stimulus
How does an electroencephalograph (EEG) work?
Records an average of the electrical potentials of the cells and fibres in the brain areas nearest to each electrode on the scalp.
What is a polysomnograph?
Combination of EEG and eye-movement records
What are alpha waves characteristic of?
Relaxation, not of all wakefulness
What name is given to a sharp wave associated with temporary inhibition of neuronal firing?
K-complex
What name is given to a burst of 12-14 Hz waves for at least half a second?
Sleep spindle
What causes sleep spindles?
Oscilating interactions between cells in the thalamus and the cortex.
They increase in number after new learning. The number of sleep spindles correlates positively with improvement in types of memory.
What happens during slow-wave sleep?
What do they indicate?
Heart rate, breathing rate, and brain activity decrease. Slow, large-amplitude waves become more common.
Neuronal activity is highly syncronised.
What does an EEG show during REM sleep?
Irregular, low-voltage fast waves that indicate increased neuronal activity.
How is REM both light and deep sleep?
Irregular, low-voltage fast waves indicate light sleep.
Postural muscles of the body, including those that support the head, are more relaxed, indicating deep sleep.
What does the sleep cycle look like?
- Stage 1
- Stage 2
- Slow-wave
- After an hour, cycle from slow-wave to Stage 2
- REM
When is REM more likely to occur?
Later in the night
How does sleep differ between age groups?
Why?
Older adults have less slow-wave sleep and more awakenings during the night.
Awakenings correlate with loss of cells in the hypothalamus and a tendency towards cognitive decline.
Is REM the same thing as dreaming?
No. REM dreams are more likely than NREM to include visual imagery and complicated plots, and people woken during REM are more like to remember their dreams. However dreaming is reported in other stages of sleep as well.
- How can an investigator determine whether a sleeper is in REM sleep?
- Examine EEG pattern and eye movements.
- During which part of a night’s sleep is REM most common?
- REM becomes most common toward the end of the night’s sleep.
How does a cut through the midbrain decrease arousal?
Damages the reticular formation, a structure that extends from the medulla into the forebrain.
What function does GABA play in sleep?
Inhibits or interrupts behaviour and promotes slow-wave sleep
How do acetylcholine, glutamate, or dopamine affect sleep?
Produce arousal in the hypothalamus, thalamus, and basal forebrain, producing wakefulness by regulating the levels of potassium and other ions that produce a state of arousal.
Why is waking up generally faster than falling asleep?
After ions are in a state that supports arousal, they tend to remain at a stable concentration.
What small structure in the pons emits burst impulses in response to meaningful events, especially those that produce emotional arousal? Axons from this area release norepinephrine widely throughout the cortex.
Locus coeruleus
What does histamine do?
How do anti-histamines work?
A pathway from the hypothalamus uses histamine as its neurotransmitter to increase arousal. Antihistamines
that cross the blood–brain barrier block those synapses.
Often used for allergies, counteract histamines and produce drowsiness unless they do not cross the blood-brain barrier.
What neurotransmitter has no effect on waking up, but is critical for staying awake? It has two names.
Orexin or hypocretin
What would happen to the sleep-wake schedule of someone who lacked orexin?
- Someone without orexin would alternate between brief periods of waking and sleeping, even during activities that would usually promote arousal.
Why do we remain asleep even though spontaneously active neurons continue firing at only slightly less than their usual rate?
Axons that release the inhibitory transmitter GABA increase their activity, interfering with the spread of information from one neuron to another. Connections from one brain area to another become wekaer. When stimulation doesn’t spread through the brain, you don’t become conscious of it.
Usually all brain areas wake up or go to sleep at nearly the same time. When might this not occur?
Sleep walking (somnambulism) Sleep walkers are asleep in most of the brain but awake in the motor cortex and a few other areas
What area of the brain is still asleep when you wake up but can’t move your limbs?
Pons
- What would happen to sleeping and waking if you took a drug that blocked GABA?
- You would remain awake, or at least somewhat conscious. (Tranquilizers put people to sleep by facilitating GABA.)
- Someone who has just awakened sometimes speaks in a loose, unconnected, illogical way. How could you explain this finding?
- People often awaken from a REM period, because REM is abundant toward morning when people usually awaken. Different brain areas don’t wake up all
at once. Shortly after awakening, certain brain areas may still be in a REM-like state, and thinking may have an illogical, dreamlike quality.
What areas of the brain see increased activity during REM sleep?
- Pons - triggers onset of REM
- Limbic system - important for emotional responses
- Parietal cortex
- Temporal cortex
What areas of the brain see decreased activity during REM sleep?
Primary visual cortex
Motor cortex
Dorselateral prefrontal cortex
What are some negative effects of sleep deprivation?
Impaired memory, cognition and attention
Magnifies unpleasant emotional reactions
Increases risk of depression
How do people with a phase delay and phase advance differ?
Phase delay - difficulty getting to sleep
Phase advance - difficulty staying asleep
What are negative effects are associated with sleep apnea?
Impaired ability to breathe while sleeping
Increased risk of stroke, heart problems
Multiple brain areas that appear to have lost neurons; deficiencies in learning, reasoning, attention, impulse control
What kinds of people are most likely to develop sleep apnea?
- Sleep apnea is most common among people with a genetic predisposition, old people, and overweight middle-aged men.
What are four main symptoms of narcolepsy? May not be visible in all patients.
- Attacks of sleepiness during the day
- Occasional cataplexy - muscle weakness while the person remains awake. Often triggered by strong emotions or great excitement.
- Sleep paralysis
- Hypnagogic hallucinations - dreamlike experiences that the person has trouble distinguishing from reality
What causes narcolepsy?
Lack of hypothalamic cells that produce and release the neurotransmitter orexin
Why do people with Huntington’s disease have trouble staying awake during the day and staying asleep at night?
Widespread damage to basal ganglia and loss of neurons in the hypothalamus, including the neurons that make orexin
Why is it not feasible to administer orexin directly?
What is used instead?
It does not readily cross the blood-brain barrier.
Stimulant drugs like Ritalin, which enhance dopamine and norepinephrine activity.
- What is the relationship between orexin and narcolepsy?
- Orexin is important for staying awake. Therefore, people or animals lacking either orexin or the receptors for orexin develop narcolepsy, characterized by bouts of sleepiness during the day.
What sleep disorder is characterised by repeated involuntary movement of the legs and sometimes arms?
Periodic limb movement disorder
What sleep disorder is characterised by vigorous movement during sleep?
REM behaviour disorder
People dream about defending themselves against attack
What are night terrors?
When do they occur?
Intense anxiety from which a person awakes screaming in terror - worse than nightmares.
During NREM sleep
1. Of the following, which shows the LEAST brain activity? A. Slow-wave sleep B. Coma C. Vegetative state D. Minimally conscious state
B. Coma
2. Sleep spindles in stage 2 sleep appear to be important for which of the following? A. Consolidation of memory B. Inhibition of impulses C. Defense mechanisms against anxiety D. Control of body temperature
A. Consolidation of memory
3. What do the high-amplitude slow waves of slow-wave sleep indicate? A. An increased level of brain activity B. Synchrony among neurons C. Muscle contractions D. Responses to sensory stimulation
B. Synchrony among neurons
- Why is REM sleep also known as paradoxical sleep?
A. Activity in the left hemisphere does not match the
activity in the right hemisphere.
B. We did not know it existed until its discovery in the 1950s.
C. It is deep sleep in some ways and light in others.
D. Because a pair of docs discovered it.
C. It is deep sleep in some ways and light in others.
- At which time, if any, is slow-wave sleep most common?
A. Immediately after falling asleep
B. Not immediately, but during the early part of the night’s sleep
C. Near the end of the night’s sleep
D. During all parts equally
B. Not immediately, but during the early part of the night’s sleep
6. What tends to activate the locus coeruleus? A. Stomach contractions B. Conflict between emotions C. Meaningful information D. Sexual desire
C. Meaningful information
- What is the role of orexin with regard to wakefulness and sleep?
A. It stimulates REM sleep.
B. It inhibits the spread of brain activity while someone is asleep.
C. It helps someone stay awake.
D. It is active during switches back and forth between wakefulness and sleep.
C. It helps someone stay awake.
- Why are people unconscious during slow-wave sleep?
A. Inhibitory transmitters block the spread of activity in the cortex.
B. The sensory receptors become unresponsive to nearly all input.
C. Spontaneous activity ceases in the neurons of the cortex.
D. Circulating hormones block the sodium gates in axon membranes.
A. Inhibitory transmitters block the spread of activity in the cortex.
- If you awaken but find you temporarily cannot move your arms or legs, what is happening?
A. You are probably developing a severe neurological disease.
B. You are probably just being lazy.
C. You need more time to get the blood flowing to your muscles.
D. Most of your brain is awake, but part of your pons and medulla remain in REM sleep.
D. Most of your brain is awake, but part of your pons and medulla remain in REM sleep.
10. Of the following, which one is not associated with an increased probability of sleep apnea? A. Having a relative with sleep apnea B. Being female C. Being overweight D. Being middle-aged
B. Being female
11. Narcolepsy is linked to a deficit of which neurotransmitter? A. Dopamine B. GABA C. Orexin D. Acetylcholine
C. Orexin
- What might one predict about the sleep of fish that live deep in the ocean?
- The deep ocean, like a cave, has no light and no difference between day and night. These fish might not need to sleep because they are equally efficient at all times of day and have no reason to conserve energy at one time more than another.
- What kind of animal tends to get more than the average amount of sleep?
- Predators get much sleep, and
so do species that are unlikely to be attacked during their sleep (such as armadillos).
Why do we need sleep?
Energy conservation in times when we aren’t using it.
Improved memory function.
- How does weakening synapses during sleep improve memory?
- Weakening the less active synapses enables the strengthened ones to stand out by contrast.
What is the biological function of REM sleep?
Possible:
- Consolidates memory
- Shakes eyeballs to get oxygen to corneas
What animals experience the most REM?
What animals experience less?
Young people get more REM than old people
Animals that sleep more generally.
E.g. Cats
Animals that sleep less.
E.g. Rabbits, sheep
How does newborns and adults differ in REM sleep?
Newborns spend 8 hours a day in REM.
Adults spend less than 2 hours.
However sleep of infants and adults is different the criteria for identifying REM sleep are different.
What hypothesis states that a dream represents the brain’s effort to make sense of sparse and distorted information?
Activation-synthesis hypothesis
What hypothesis regards dreams as thinking that takes place under unusual circumstances, emphasizing that dreams begin with spontaneous brain activity related to recent memories?
Neurocognitive hypothesis
So the idea is that either internal or external stimulation activates parts of the parietal, occipital, and temporal cortex. The arousal develops into a hallucinatory perception, with no sensory input from area V1 to override it. This idea, like the activationsynthesis hypothesis, is hard to test because it does not make specific predictions about who will have what dream and when.
Why do we forget most dreams when we wake up, and lose track of what’s happening in dreams resulting in sudden scene changes?
Activity is suppressed in the pre-frontal cortex, which is important for working memory.
- According to the neurocognitive hypothesis, why do we have visual imagery during dreams?
Why do dreams sometimes make an incoherent or illogical story?
- We have visual imagery because areas of the visual cortex other than the primary visual cortex become active, without any input from the eyes.
Dreams are sometimes incoherent or illogical because low activity in the prefrontal cortex means poor memory for what has just happened.
- Certain animal species have evolved to sleep very little under which of these circumstances?
A. The animals can easily find an abundance of food.
B. The environment is about the same 24 hours a day.
C. The weather often changes drastically from one day to the next.
D. Several closely related species live in the same geographical area.
B. The environment is about the same 24 hours a day.
- How do whales and dolphins get oxygen at night?
A. They absorb oxygen from the water.
B. They sleep in just one hemisphere at a time.
C. They lower their metabolism so that they need to breathe only a few times per night.
D. They store oxygen in their digestive system.
B. They sleep in just one hemisphere at a time.
- When frigate birds spend weeks at sea, what do they do about sleep?
A. They sleep while floating on the water.
B. They sleep only in brief episodes, and not much overall.
C. They go without sleep altogether.
D. They sleep as much as usual, but while gliding.
B. They sleep only in brief episodes, and not much overall.
- If we want to predict how many hours a day some species sleeps, which of these questions would be most helpful in making
that prediction?
A. What color is the animal?
B. Does the animal live north or south of the equator?
C. What does the animal eat?
D. How intelligent is the animal?
C. What does the animal eat?
- Sleep often improves memory. How?
A. Synapses increase their supply of serotonin and norepinephrine.
B. Certain synapses become weakened, enabling others to stand out by contrast.
C. Overall brain activity increases.
D. The brain increases
B. Certain synapses become weakened, enabling others to stand out by contrast.
- Of the following groups, which one tends to spend the highest percentage of sleep in the REM stage?
A. Infants
B. Those who sleep only a few hours per night
C. Prey animals, such as sheep and horses
D. Teenagers
A. Infants
- According to the neurocognitive hypothesis, what are dreams?
A. Dreams are disguised representations of unconscious wishes.
B. Dreams are reactions to whatever sensory stimuli are present at the time.
C. Dreams are memories of the experiences of our ancestors.
D. Dreams are thinking that occurs under unusual conditions.
D. Dreams are thinking that occurs under unusual conditions.
When does the pineal gland start to release melatonin?
About 2 hours before sleep
How do we actively go to sleep?
???
How do we passively go to sleep?
Build up of ‘sleep pressure’
- Adenosine accumulates during the day, produces sleepiness
- Declines during sleep
- Inhibited by caffeine
Prostaglandins
- Accumulate during the day, promotes sleep
- Declines during sleep
- Inhibits hypothalamic cells that raise arousal
Which part of the brain may be responsible for REM sleep?
Dorsal raphe
Inhibition from dorsal raphe provides excitation - not enough to wake us up, but to stimulate parts of the hypothalamus.
What determines the amplitude of an EEG?
Number of neurons contributing to it.
When more neurons are active at the same time, the EEG amplitude will tend to be larger.
Why do we see greater amplitudes in EEG during sleep than when awake even though the brain is more active when we are awake?
Populations of neurons are active at the same time during sleep doing the same things - synchrony - therefore we get larger amplitudes during sleep.
Why might we tune an EEG to pick up specific frequencies?
E.g.
- To detect when someone moves into a different sleep stage.
- To detect when someone is not paying attention.
How does EEG amplitude AND frequency change when moving from light sleep to deep sleep?
Amplitude increases
Frequency decreases
What’s a real world application for EEG?
Waking pilots during Stage 1 or 2 of their sleep instead of 3 or 4 so they aren’t as groggy.
What’s an event related potential (ERP)?
Brain waves that occur in response to a stimulus
