Chapter 8

Question 1

Endogenous Circannual Rhythms

ANd

endogenous circadian rhythms

Answer 1

Some animals generate endogenous circannual
rhythms, internal mechanisms that operate on an
annual or yearly cycle
– Example: birds migratory patterns; animals storing food
for the winter

All animals produce endogenous circadian rhythms,
internal mechanisms that operate on an approximately
24-hour cycle
– Sleep cycle
– Frequency of eating and drinking
– Body temperature
– Secretion of hormones
– Urination
– Sensitivity to drugs

notes from lecture:
effected by external cues
environmental change can have major impact on animals migratory patterns

book: your urge to sleep depends partly on the time of day , not just how many hours you’ve been awake.

Question 2

The Daily Activity of a Squirrel Kept in Total Darkness

Answer 2

Book:
Represents the activity of a flying squirrel kept in total darkness for 25 days
Each horizontal line represent one 24-hour day
A thickening of the line represent a period of activity by the animal
Even in this unchanging environment , the animal produce a regular rhthym of activity and sleep.

Waking period starts earlier each day than the last
Sleep period starts earlier each day than the last
check diagram 5

Question 3

Daily Pattern of Body Temperature

Answer 3

slide 6
human body temp at 37 degrees normally
it will fluctuate over the course of the day from a low of 36.7 at night to almost 37.2 in the afternoon

Question 4

Daily Pattern of Positive Moods

Answer 4

slide 7

Question 5

Setting and Resetting the Biological Clock
Purpose of it ?
How long is the clock ?

Answer 5

The purpose of the circadian rhythm is to keep our
internal workings in phase with the outside world
• The human circadian clock generates a rhythm slightly
longer than 24 hours when it has no external cue to set
it
• Resetting our circadian rhythms is sometimes
necessary

Question 6

Zeitgeber:

means what in german ?

Answer 6

German meaning “time giver”; refers to the
stimulus that resets the circadian rhythm
– Examples: sunlight, tides, exercise, meals, arousal of
any kind, meals, temperature of environment, and so on. – Depression, irritability, and impaired job performance are
effects of using something other than sunlight as a
zeitgeber

Question 7

Difference in Sun Time Between East and West Germany

Answer 7

half an hour difference between the east and west
so, the sun in the east rise 30 min before the west
everyone in germany are on the same clock time
People at the eastern edge has a sleep midpoint about 30 min earlier than those at the west .
This correspond to the rising of the sun

Question 8

Jet Lag

Answer 8

Refers to the disruption of the circadian rhythms due to
crossing time zones
– Stems from a mismatch of the internal circadian clock
and external time – Sleepiness during the day, sleeplessness at night, and
impaired concentration
• Traveling west “phase-delays” our circadian rhythms
• Traveling east “phase-advances” our circadian rhythms

Question 9

Is it more difficult to fly east or west ?

why ?

Answer 9

More Difficult Flying East
Book:
Going west, we stayed awake later at night and then awaken late the next morning , already partly adjusted to the new schedule. Called phase delay our circadian rythms .

East : phase advance , to sleep earlier and to wake up earlier.

Question 10

Shift Work

Answer 10

Sleep duration depends on when one goes to sleep
• Working at night does not reliably change the circadian
rhythm
– Even after long periods of working at night, people can
still feel groggy, sleep poorly during the day, and body temperature peaks while sleeping instead of while working
• People adjust best to night work if they sleep in a very
dark room during the day and work under very bright
lights at night

Question 11

Morning People and Evening People

Answer 11

Cycles can differ between people and lead to different
patterns of wakefulness and alertness • Change as a function of age
– Young children are morning people
– Adolescents are often night people • As an adult, it partially depends upon genetics

book:
circadian rhythm differs among ppl
morning ppl: awaken early, quickly become productive and become less alert as the day progresses

night owl: warm up slowly, reaching their peak in the afternoon , or evening. They tolerate staying up all night better than morning ppl .5

Question 12

Age and Gender Differences in Circadian Rhythms

Answer 12

slide 15
Notes from ppw:
Midpoint is lower for women than it is for men
This is the case until the 60s
13 hours for men , which they would normally sleep for

Question 13

Mechanisms of the Biological Clock

Answer 13

Mechanisms of the circadian rhythms
– The suprachiasmatic nucleus (SCN)
– Genes that produce certain proteins
– Melatonin levels

Question 14

the Suprachiasmatic Nucleus (SCN)

Answer 14

The main control center of the circadian rhythms of
sleep and temperature
– Located above the optic chiasm and part of the
hypothalamus
• Damage to the SCN results in less consistent body
rhythms that are no longer synchronized to
environmental patterns of light and dark

Supra = above the optic chiasm

Question 15

The Suprachiasmatic Nucleus (SCN) and the Circadian Rhythm

Answer 15

Generates circadian rhythms in a genetically controlled,
unlearned manner • Single cell extracted from the SCN and raised in tissue
culture continues to produce action potential in a
rhythmic pattern • Various cells communicate with each other to sharpen
the circadian rhythm

Question 16

The Suprachiasmatic Nucleus (SCN) and the Retinohypothalamic Path

Answer 16

Light resets the SCN via a small branch of the optic
nerve called the retinohypothalamic path
– Travels directly from the retina to the SCN
• The retinohypothalamic path comes from a special
population of ganglion cells that have their own
photopigment called melanopsin
– The cells respond directly to light and do not require any
input from the rods or cones

Notes from class:
If you keep your eyes away from light, you can trick your brain
blind ppl have medications that we give to them in order to reset your SCN

Question 17

The Biochemistry of the Circadian Rhythm

what are the 2 genes for generating the circadian rythm

Answer 17

Two types of genes are responsible for generating the
circadian rhythm
– Period: produce proteins called PER
– Timeless: produce proteins called TIM
• PER and TIM proteins increase the activity of certain
kinds of neurons in the SCN that regulate sleep and
waking
– Mutations in the PER gene result in odd circadian
rhythms or decreased alertness if deprived of a good night’s sleep

Question 18

Interaction of MRNA with PER and TIM Proteins

Answer 18

check diagram on slide 23

Question 19

Melatonin

Answer 19

The SCN regulates waking and sleeping by controlling
activity levels in other areas of the brain
• The SCN regulates the pineal gland, an endocrine
gland located posterior to the thalamus
• The pineal gland secretes melatonin, a hormone that
increases sleepiness

Melatonin secretion usually begins two to three hours
before bedtime
• Melatonin feeds back to reset the biological clock
through its effects on receptors in the SCN
• Melatonin taken in the afternoon can phase-advance
the internal clock and can be used as a sleep aid

Question 20

Sleep

Answer 20

Sleep is a state that the brain actively produces
– Characterized by a moderate decrease in brain activity
and decreased response to stimuli
• Sleep differs from the following states:
– Coma, vegetative state, minimally conscious state, and
brain death

Question 21

Relaxation and Stage 1 Sleep

Answer 21

Alpha waves are present when one begins a state of
relaxation
• Stage 1 sleep is when sleep has just begun
– The EEG is dominated by irregular, jagged, and low
voltage waves – Brain activity begins to decline

Question 22

Stage 2 Sl eep

Answer 22

Stage 2 sleep is characterized by the presence of:
– Sleep spindles: 12- to 14-Hz waves during a burst that
lasts at least half a second – K-complex: a sharp wave associated with temporary
inhibition of neuronal firing

Question 23

Slow Wave Sleep—Stage 3 and Stage 4

Answer 23

Stage 3 and stage 4 together constitute slow wave
sleep (SWS) and is characterized by:
– EEG recording of slow, large amplitude wave
– Slowing of heart rate, breathing rate, and brain activity
– Highly synchronized neuronal activity

Question 24

Paradoxical or REM Sleep

Answer 24

Rapid eye movement sleep (REM) describes periods characterized by rapid eye movements during sleep – Also know as paradoxical sleep: deep sleep in some
ways, but light sleep in other ways
• EEG waves are irregular, low-voltage, and fast • Postural muscles of the body are more relaxed than
other stages

Question 25

Polysomnograph Records

Answer 25

check slide 36

Question 26

NREM and REM Cycles

Answer 26

Stages other than REM are referred to as non-REM sleep (NREM) • When people fall asleep, they progress through stages 1, 2, 3, and 4 in sequential order – After about an hour, the person begins to cycle back through the stages from stage 4 to stages 3 and 2 and then REM – The sequence repeats with each cycle lasting approximately 90 minutes Stages 3 and 4 sleep predominate early in the night – Length of stage decreases as the night progresses • REM sleep is predominant later at night – Length increases as the night progresses • REM is strongly associated with dreaming, but people also report dreaming in other stages of sleep

Question 27

Typical Sequences of Sleep Stages

Answer 27

check slide 39

Question 28

Brain Mechanisms of Wakefulness and Arousal—The Reticular Formation

Answer 28

Various brain mechanisms are associated with wakefulness and arousal • The reticular formation is a part of the midbrain that extends from the medulla to the forebrain and is responsible for arousal

Question 29

The Pontomesencephalon

Answer 29

The pontomesencephalon, a part of the reticular formation in the midbrain, contributes to cortical arousal – Axons extend to the hypothalamus, thalamus, and basal forebrain, which release acetylcholine, glutamate, or dopamine – Produce excitatory effects to widespread areas of the cortex – Stimulation of the pontomesencephalon awakens sleeping individuals and increases alertness in those already awake

Question 30

The Locus Coeruleus

Answer 30

The locus coeruleus is a small structure in the pons whose axons release norepinephrine to arouse various areas of the cortex and increase wakefulness – Usually dormant while asleep

Question 31

The Hypothalamus

Answer 31

The hypothalamus contains neurons that release “histamine” to produce widespread excitatory effects throughout the brain – Antihistamines produce sleepiness

Question 32

Orexin

Answer 32

The lateral and posterior nuclei of the hypothalamus releases orexin – Orexin is a peptide neurotransmitter and is sometimes also called hypocretin – Needed to stay awake rather than wake up – Orexin is released by cells into the basal forebrain to stimulate neurons responsible for wakefulness and arousal – The basal forebrain is an area just anterior and dorsal to the hypothalamus

Question 33

GABA and Acetylcholine

Answer 33

Cells of the basal forebrain release the inhibitory neurotransmitter GABA – Inhibition provided by GABA is essential for sleep • Other axons from the basal forebrain release acetylcholine, which is excitatory and increases arousal

Question 34

Brain Mechanisms of Sleeping and Waking

Answer 34

slide 46

Question 35

Functions of the inhibitory neurotransmitter GABA are | also important for:

Answer 35

Decreasing the temperature and metabolic rate | – Decreasing the stimulation of neurons

Question 36

Sleep as a Local Phenomenon | Sleepwalker, lucid dreams

Answer 36

Sleep can be localized within the brain – Sleepwalkers: awake in one part of the brain and asleep in others – Lucid dreaming: dreaming but aware of being asleep and dreaming – The pons remaining in REM while other brain areas wake up: causes the inability to move

Question 37

During REM sleep:

Answer 37

Activity increases in the pons and the limbic system – Activity decreases in the primary visual cortex, the motor cortex, and the dorsolateral prefrontal cortex REM sleep is also associated with a distinctive pattern of high-amplitude electrical potentials known as PGO waves – Waves of neural activity are detected first in the pons, then in the lateral geniculate of the hypothalamus, and then the occipital cortex • REM deprivation results in a high density of PGO waves during uninterrupted sleep

Question 38

How does it inhibit movement during REM sleep ?

Answer 38

• Cells in the pons send messages to the spinal cord, which inhibits motor neurons that control the body’s large muscles – Prevents motor movement during REM sleep

Question 39

REM is regulated by which NT

Answer 39

REM is also regulated by serotonin and acetylcholine – Drugs that stimulate acetylcholine receptors quickly move people to REM – Serotonin interrupts REM

Question 40

PGO Waves and REM Sleep

Answer 40

sldie 53

Question 41

Insomnia:

Answer 41

A sleep disorder associated with inadequate sleep – Caused by a number of factors, including noise, stress, pain, diet, and medication – Can also be the result of disorders such as epilepsy, Parkinson’s disease, depression, anxiety or other conditions – Dependence on sleeping pills or alcohol and shifts in the circadian rhythms can also result in insomnia

Question 42

Sleep Disorders as a Result of Phase Delay

Answer 42

slide 55

Question 43

Sl eep Apnea

Answer 43

A sleep disorder characterized by the inability to breathe while sleeping for a prolonged period of time – Consequences: sleepiness during the day, impaired attention, depression, and sometimes heart problems – Causes: genetics, hormones, old age, obesity and deterioration of the brain mechanisms that control breathing – Effects: cognitive impairment may result

Question 44

Narcolepsy (

Answer 44

A sleep disorder characterized by frequent periods of sleepiness – Attacks of sleepiness during the day – Gradual or sudden attack of sleepiness – Occasional cataplexy: muscle weakness triggered by strong emotions – Sleep paralysis: inability to move while falling asleep or waking up – Hypnagogic hallucinations: dreamlike experiences Seems to run in families, although no gene has been identified • Caused by lack of hypothalamic cells that produce and release orexin • Primary treatment is with stimulant drugs (i.e., Ritalin), which increase wakefulness by enhancing dopamine and norepinephrine activity

Question 45

Periodic Limb Movement Disorder

Answer 45

The repeated involuntary movement of the legs and sometimes the arms while sleeping – Legs kick once every 20–30 seconds for periods of minutes to hours – Usually occurs during NREM sleep

Question 46

REM Behavior Disorder

Answer 46

Associated with vigorous movement during REM sleep – Usually associated with acting out dreams • Research suggest that inadequate GABA and other inhibitory neurotransmitters may be responsible

Question 47

Night Terrors and Sleepwalking

Answer 47

Night terrors are experiences of intense anxiety from which a person awakens screaming in terror – Usually occurs in NREM sleep • “Sleepwalking” runs in families, mostly occurs in young children, and occurs mostly in stage 3 or 4 sleep – Not associated with dreaming It is not dangerous to wake a sleepwalker • A condition similar to sleepwalking is sexsomnia: engaging in sexual behavior while asleep • Can pose a threat to romances and marriages

Question 48

Why Sleep? Why REM? Why Dreams?

Answer 48

We’ve evolved mechanisms to force us to sleep • Inhibitory processes in our brains force us to become less aroused and less alert, and thus to sleep

Question 49

Functions of Sleep

Answer 49

Some of the many functions of sleep include: – Resting muscles – Decreasing metabolism – Performing cellular maintenance in neurons – Reorganizing synapses – Strengthening memories

Question 50

Sleep and Energy Conservation

Answer 50

The original function of sleep was probably to conserve energy • Conservation of energy is accomplished via: – Decrease in body temperature of about 1–2 Celsius degrees in mammals – Decrease in muscle activity

Question 51

Hibernation is Analogous to Sleep

Answer 51

Decrease in body temperature to only slightly above that of the environment • Heart rate and brain activity drop to almost nothing • Neuron cell bodies shrink, and dendrites lose almost a fourth of their branches – Replaced later when body temperature increases

Question 52

Some Facts About Hibernation

Answer 52

Bear “hibernation” is not as extreme as that of smaller hibernators such as bats and ground squirrels • Hibernating animals come out of hibernation for a few hours every few days • Hibernation retards the aging process • Hibernation is also a period of relative invulnerability to infection and trauma

Question 53

Species Differences in Sleep

Answer 53

Animals sleep habits and are influenced by particular aspects of their life, including: – Whether they are predator or prey – How many hours they spend each day devoted to looking for food – Safety from predators while they sleep § Examples: sleep patterns of dolphins, migratory birds, and swifts check slide 70

Question 54

Sleep and Memory

Answer 54

Sleep also plays an important role in enhancing learning and strengthening memory – Performance on a newly learned task is often better the next day if adequate sleep is achieved during the night • Increased brain activity occurs in the area of the brain activated by a newly learned task while one is asleep Patterns of activity in the hippocampus during learning were similar to those shown during sleep – Suggests that the brain replays its daily experiences during sleep • The brain strengthens some synapses and weakens others during sleep • Sleep spindles increase in number after new learning: correlated with nonverbal IQ

Question 55

Amounts of REM Sleep human cat

Answer 55

Humans spend one-third of their life asleep; about one- fifth is spent in REM • Species vary in amount of sleep time spent in REM – Cats spend up to 16 hours a day sleeping with lots of that time in REM sleep – Percentage of REM sleep is positively correlated with the total amount of sleep in most animals – Among humans, those who get the most sleep have the highest percentage of REM

Question 56

Functions of REM Sleep

Answer 56

Research is inconclusive regarding the exact functions of REM • During REM: – The brain may discard useless connections – Learned motor skills may be consolidated • Maurice (1998) suggests the function of REM is simply to shake the eyeballs back and forth to provide sufficient oxygen to the corneas slide 75 - diagram

Question 57

blind ppl

Answer 57

Book : Some do their circadian rhythm by noise , temp, meals and activity, Some ppl are not too sensitive to these stimuli so, produce free running circadian rhythm (no stimulation reset or alerts it) that are a little longer than 24 hours