Chapter 13

Question 1

What are biorhythms?

Answer 1

cyclical changes in behavior or bodily functions

Question 2

What is a period?

Answer 2

the time required to complete one cycle of activity.

Question 3

What are circannual rhythms?

Answer 3

Circannual rhythms have a period of about a year.

Question 4

What are infradian rhythms?

Answer 4

have monthly or seasonal periods greater than a day but less than a year.

Question 5

What are circadian rhythms?

Answer 5

daily period

Question 6

What are ultradian rhythms?

Answer 6

Rhythms that have a period that’s less than a day

Question 7

Why are circadian rhythms important?

Answer 7

A circadian biorhythm allows an organism to make adjustments to day and night changes and to the relative lengthening and shortening of day and night at the latitude at which it lives. A circannual biorhythm helps an animal adapt to the environmental changes that occur over a year, especially if it lives in northern and southern climates.

Question 8

What functions have circadian rhythms?

Answer 8

Just as human waking and sleep behavior have a circadian rhythm, so also do pulse rate, blood pressure, body temperature, rate of cell division, blood cell count, alertness, urine composition, metabolic rate, sexual drive, feeding behavior, responsiveness to medications, cognitive ability, and emotions.

Question 9

What produces circadian rhythms?

Answer 9

Circadian rhythms are produced by an endogenous (internal) mechanism referred to as a biological clock.

Question 10

What is the importance of the biological clock?

Answer 10

A circadian clock signals that if daylight lasts for a given time today, it will last for about the same time tomorrow. A circadian clock allows us to anticipate events and prepare for them both physiologically and cognitively. And unless external factors get in the way, a circadian clock regulates feeding times, sleeping times, and metabolic activity as appropriate to day–night cycles. Circadian clocks also produce epigenetic effects: they influence gene expression in every cell in the body (Gaucher et al., 2018).

Question 11

What does behavioural analysis need?

Answer 11

Behavioral analysis requires a method for counting behavioral events, as well as a method for displaying those events in a meaningful way.

Question 12

How are circadian rhythms measured?

Answer 12

A computer records each turn of the wheel and displays the result (Figure 13-2B). Because rats are nocturnal, sleeping during light hours and becoming active during dark hours, their wheel running takes place in the dark. If each day’s activity is plotted under the preceding day’s activity in a column, we observe a pattern—a cycle of activity over time. A glance at the pattern reveals when and how active the animal is (Figure 13-2C). Electronic innovations that place movement sensors in smart watches and smartphones are now used to measure the circadian activity of human participants.

Question 13

How do we determine whether a rhythm is produced by a biological clock?

Answer 13

researchers can conduct one of a number of tests in which they manipulate conditions. A test may be given (1) in continuous light, (2) in light of varying brightness, (3) in continuous darkness, (4) by light choice of the participant, or (5) with eating, activity, and sleep times all regulated. Each treatment yields a slightly different insight into the period of the biological clock.

Question 14

What is a free running rhythm?

Answer 14

one that has a period of the body’s own devising.

Question 15

How does the light related biology of a species influence the period of free-running periods?

Answer 15

When hamsters, a nocturnal species, are tested in constant darkness, their free-running periods are a little shorter than 24 hours; when they are tested in constant light, their free-running periods are a little longer than 24 hours. In the constant darkness test with two closely related species, rats have a cycle that expands slightly, and mice have a cycle that contracts slightly.

Question 16

What is a Zeitgeber?

Answer 16

A clock setting cue

Question 17

What does entrained mean?

Answer 17

When a Zeitgeber resets a biorhythm, the rhythm is said to be entrained.

Question 18

What happens when a clock is entrained?

Answer 18

When its biological clock is entrained, an animal is able to organize its daily schedule, including when to eat, exercise, and sleep. For some animals that live in polar regions, the constant light of summer and the constant dark of winter exceed their clock’s capacity to adjust; for those animals, the clock turns off. The light Zeitgeber is most effective for humans at both sunrise and sunset. There are many nonphotic Zeitgebers, however, including ambient temperature, activity, mealtimes, work, and social events that can in some circumstances entrain the circadian rhythm if the event occurs at the same time each day.

Question 19

What role does light’s importance play in entraining clocks in the case of SAD?

Answer 19

One explanation of seasonal affective disorder (SAD), a form of depression displayed by as many as 10 percent of people who live in northern latitudes, is that low levels of sunlight in winter do not entrain the circadian rhythm.
Because people vary in the duration of their free-running rhythms, lack of entrainment affects individuals differently. Some people are phase-retarded, with desired sleep time coming earlier each day; some are phase-advanced, with desired sleep time coming later each day. Zhang and colleagues (2016) have described variants in the Period gene, one of the genes that is involved in timing the circadian cycle, which may be related to the susceptibility to display SAD and the phase-advanced feature of the circadian rhythm. By preparing mice with the Period gene knocked out, these researchers produced mice with a depressive phenotype. Such findings support an association between altered circadian rhythms and depression.

Question 20

How does phototherapy work?

Answer 20

Because a class of retinal ganglion cells that express a photosensitive pigment called melanopsin are responsive to blue light (see Section 13-2), it has been proposed that exposure to bright white light that contains this blue frequency can reset the circadian clock and ameliorate depression. In this treatment, called phototherapy, the idea is to increase the short winter photoperiod by exposing someone to artificial bright light.

Question 21

What is light pollution?

Answer 21

When we stay up late in artificial light, sleep late some days, and get up early by using an alarm clock on other days, we disrupt our circadian rhythm. Light pollution, the extent to which artificial lighting floods our workplaces, homes, and environment, also disrupts the circadian rhythm.
- Increase w/ LEDs (don’t filter blue light)

Question 22

What can occur as a result of circadian rhythm disruption?

Answer 22

Disruptions of the circadian rhythm account for inconsistent behavior associated with accidents, daytime fatigue, alterations in emotional states, obesity, diabetes, and other disorders characteristic of metabolic syndrome

Question 23

What is jet lag?

Answer 23

The difference between a person’s circadian rhythm and the daylight cycle in a new environment can produce the disorientation and fatigue of jet lag.

Question 24

What is the superchiasmatic biological clock?

Answer 24

the suprachiasmatic nucleus (SCN), acts as the master biological clock

Question 25

What is the evidence showing that the SCN is the CNS’ biological clock?

Answer 25

including the loss of rhythmical eating, drinking, and exercise after brain damage; the activity of SCN cells during light phases of the cycle; and the presence of a pathway from the eye to the SCN.

Question 26

How does the SCN receive information?

Answer 26

through the retinohypothalamic tract, a pathway from the retina to the SCN

Question 27

What is a dimer?

Answer 27

The combined protein, called a dimer (for two proteins), then inhibits the genes that made its original constituent proteins.

Question 28

What are the steps of the clockwork feedback loop?

Answer 28

STEP 1: TRANSCRIPTION In the cell nucleus, one of three Period genes (Per1,*Per2, Per3) and one of two Cryptochrome genes (Cry1, Cry2) are transcribed into the appropriate Per or Cry mRNA.

STEP 2: TRANSLATION Ribosomes in the endoplasmic reticulum translate these mRNAs into the appropriate PER† and CRY proteins. In the extranuclear fluid, the two proteins come together to form a dimer, or two-protein combination of PERCRY.

STEP 3: INHIBITION The PERCRY dimer enters the cell nucleus, where it binds to and inhibits the Enhancer box (Ebox), a part of the DNA that activates transcription of the Period and Cryptochrome genes. The result of this inhibition is that Per and Cry are no longer produced.

STEP 4: DECAY After it plays its inhibitory role, the PERCRY dimer decays. When this occurs, the Per and Cry genes resume expression, and the 24-hour cycle begins anew.

Question 29

What is the process of pacemaking circadian rhythms?

Answer 29

Light entrains the SCN, and the SCN in turn drives a number of slave oscillators. Each slave oscillator is responsible for the rhythmic occurrence of one activity. In other words, drinking, eating, body temperature, and sleeping are each produced by a separate slave oscillator.

Question 30

What pathways does the clock use to entrain slave oscillators?

Answer 30

SCN neurons send axonal connections to nuclei close by in the hypothalamus and thalamus. The SCN connects with pituitary endocrine neurons. The SCN also sends indirect messages to autonomic neurons in the spinal cord to inhibit the pineal gland from producing the hormone melatonin, which influences daily and seasonal biorhythms. SCN cells themselves release hormones. Thus, through multiple pathways, the SCN exerts its control on the entire body.

Question 31

What is the best example for displaying the SCN’s effects?

Answer 31

1. Glucocorticoids

2. Melatonin

Question 32

What does melatonin do?

Answer 32

Melatonin promotes sleep and activates the parasympathetic rest-and-digest system, as well as other physiological events in the body.

Question 33

What do glucocorticoids do?

Answer 33

Glucocorticoids mobilize glucose for cellular activity to support arousal responses in the sympathetic system

Question 34

When are these hormones active?

Answer 34

Thus, melatonin promotes rest activities during the dark portion of the circadian cycle, and glucocorticoids promote arousal activities during the light portions of the circadian cycle.

Question 35

How does melatonin production affect hamsters?

Answer 35

During the long daylight period of the circadian cycle, the SCN inhibits melatonin secretion by the pineal gland. As the days become shorter, the melatonin release increases. When the daylight period is shorter than 12 hours, melatonin release time becomes sufficient to inhibit the hamster’s gonads, and they shrink. Melatonin also influences the testes of short-day breeders, such as sheep and deer, that mate in the fall and early winter. Melatonin’s effect on reproductive behavior in these species is the reverse of that in the hamster: reproductive activities begin as melatonin release increases

Question 36

What are chronotypes?

Answer 36

variation in circadian activities among individuals

Question 37

What causes the lark and owl chronotypes?

Answer 37

These “lark” and “owl” chronotypes are likely produced by differences in SCN neurons and the genes that influence the clock in those neurons. A large number of genes contribute to the function of the mammalian biological clock, and alleles of these genes are associated with chronotypes.

Question 38

What can circadian rhythms also influence?

Answer 38

emotional experience, learning and retention, decision making, and motivation.

Question 39

What is the relationship between time of day and performance?

Answer 39

First, synchrony between time of day and chronotype is a dominant effect: morning people do better in the morning, and evening people do better in the evening. Second, highly practiced behaviors are not influenced much by time-of-day effects. Third, some large differences between young and old people related to performance and time of day are likely related to chronotype. Finally, a weakness in studies of time-of-day effects is that they depend on self-reports of chronotype. More rigorous studies will depend on determining chronogenotype—that is, which chronotype allele people have.

Question 40

Define time stamping

Answer 40

the idea that memory for learned items is better when test–retest is given at the same time of the circadian cycle

Question 41

How does the circadian rhythm influence decision making?

Answer 41

Anticipatory activity might also include recalling events related to the timing of feeding and food location. Many cognitive activities can occur in the absence of the SCN, but it is adaptive for them to occur at the right time and place. SCN activity enables this. As animals age, their ability to associate appropriate activity with appropriate time declines, impairing their daily schedule, an effect that might in part account for poor scheduling and sleep in some older humans (Mulder et al., 2015). In athletics, there is a strong home advantage for many sports, and it is likely that the advantage stems from a time-of-day effect in which competition fits into a home daily schedule better than an away schedule

Question 42

How do circadian rhythms influence emotional behaviour?

Answer 42

Studies also find that the circadian period influences emotional behavior. A time-of-day effect may account for some of our emotional responses to daily events, independent of the events themselves. An interesting example is fear. Nighttime fear is common, but is it the dark or the nighttime circadian rhythm that accounts for heightened emotion? By independently varying lighting conditions and test times during the circadian cycle, Li and colleagues (2015) found heightened emotional responses to stimuli at night, independent of ambient lighting. Thus, the cycle, not just darkness, contributes to emotional responding. Apparently, at least two factors explain why horror movies watched at night are scary: the movie’s content and the time-of-day effect.

Question 43

Define self report

Answer 43

One measure of sleeping and waking behavior is self-report: people record in a diary when they wake and when they retire to sleep.

Question 44

What is the recommended sleep duration by age?

Answer 44

Age	                                Sleep time (hours)
Newborn up to 3 months	14–17
Infant under 1 year.     	12–15
Toddler up to 3 years	11–14
Preschool	10–13
Elementary-school age	  9–11
Adolescent:	  8–10
Adult: 7–9
Adult 65 years and older: 7–8

Question 45

What 3 electrical body signals are needed for measuring sleep?

Answer 45

brain activity, muscle activity, and eye movement.

Question 46

What is the difference between an EEG, EMG and EOG?

Answer 46

Electrodes pasted onto standard locations on the skull’s surface yield an electroencephalogram (EEG), a record of brain-wave activity. Electrodes placed on neck muscles provide an electromyogram (EMG), a record of muscle activity. Electrodes located near the eyes provide an electrooculogram (EOG), a record of eye movements. Body temperature, circulating hormones, and blood glucose levels provide additional measures of sleep.

Question 47

What does the EEG record show?

Answer 47

EEG recording shows distinct patterns of brain-wave activity for states categorized as awake, relaxed, drowsy, sleep, deep sleep, and dreaming

Question 48

Compare REM and non-REM sleep

Answer 48

this twitching is periodic and is also associated with rapid eye movements (REMs) and an awake pattern in the EEG record. Since their report, the conventional classification has been to refer to this state of sleep as REM sleep (R-sleep) and to refer to other sleep states as non-REM (NREM) sleep (N-sleep).

Question 49

Describe the waking state

Answer 49

The W state represents behavior varying from alert wakefulness to drowsiness. When a person is awake, the EEG pattern consists of small-amplitude (height) waves with a fast frequency (repetition period). This pattern, the beta rhythm, is defined by a frequency of 15 to 30 Hz (times per second). The pattern is also called fast-wave activity-activated EEG, or waking EEG. Associated with waking, the EMG is active, and the EOG indicates that the eyes move.

Question 50

What is alpha rhythm?

Answer 50

These are large, extremely regular brain waves with a frequency ranging from 7 to 11 Hz. Humans generate alpha rhythms in the region of the visual cortex at the back of the brain, and the rhythms abruptly stop if a relaxed person is disturbed or opens his or her eyes. Not everyone displays alpha rhythms, and some people display them much more strongly than others.

Question 51

Describe N1 sleep

Answer 51

• Sleep onset
• EEG indicates beta wave activity —> low amplitude, mixed frequency activity which includes 4 to 7 Hz theta wave activity
• the EMG remains somewhat active, as the muscles have tone, and the EOG typically indicates that the eyes can be rolling.

Question 52

Describe N2 sleep

Answer 52

In this behavioral state, a person continues to produce theta waves but also produces periodic sleep spindles (brief runs of 11- to 16-Hz rhythmic waves) and K-complexes, well-defined sharp waves followed by slow waves, all lasting for about a half-second.

Question 53

Describe N3 sleep

Answer 53

A person in this behavioral state is difficult to arouse, groggy when aroused, and quick to go back to sleep when undisturbed. The EEG is characterized by larger-amplitude, slow EEG waves called delta rhythms. Still, the EMG indicates muscle activity, signifying that the muscles retain tone, although the EOG indicates that the eyes do not move.

Question 54

Describe R sleep

Answer 54

R-sleep consists of periods when a sleeper is relatively still and periods when the eyes display REMs, as indicated by the EOG, and the mouth, fingers, and toes twitch. Other than these movements, the EMG indicates that muscles are inactive, a condition termed atonia (Greek via Latin, meaning “without tone”). The EEG displays a beta rhythm similar to that displayed in the W stage and N1 stage.

Question 55

What is a hypnogram?

Answer 55

• Sleep graph, also called a somnogram

Question 56

Interpret Fig 13.14

Answer 56

Notice that the depth of sleep, as indicated by a progression from N1 through N3, changes several times through the night and that each of these progressions is followed by an R-sleep stage. This N–R sequence lasts approximately 90 minutes and occurs five times in the course of the participant’s sleep period. The labels indicating R-sleep in Figure 13-14 tell us that the sleep stage durations roughly divide sleep into two parts: the first is dominated by N-sleep and the second dominated by R-sleep.

Question 57

What physiological stages are associated with N-sleep?

Answer 57

body temperature declines, heart rate and blood flow decrease, body weight decreases from water loss in perspiration, and growth hormone levels increase. N-sleep is also the time when we toss and turn in bed, pull on the covers, and engage in other movements.

Question 58

Describe RLS

Answer 58

Restless legs syndrome (RLS) is a disorder in which people experience unpleasant sensations in the legs, described as creeping, crawling, tingling, pulling, or painful, often accompanied by periodic leg movements. One or both legs may be affected, and sometimes the arms may also be affected. RLS affects around 5 percent of the population, more commonly women than men. In mild cases, massage, exercise, stretching, and hot baths may be helpful. For more severe cases, patients can restrict their intake of caffeine and take benzodiazepines to help them get to sleep.

L-Dopa, a drug used to treat Parkinson disease, is frequently used as a treatment. RLS has been associated with poor iron uptake, especially in the substantia nigra, and some people have been helped by iron supplements. One focus of research into RLS is to improve iron absorption by the brain.

Question 59

What physiological changes occur during R sleep?

Answer 59

During R-sleep, mechanisms that regulate body temperature stop working, and body temperature moves toward room temperature. You may wake up from R-sleep feeling cold or hot (or because you are cold or hot), depending on the temperature of the room, because your body has drifted toward room temperature during an R-sleep period. During portions of R-sleep, eyes move; toes, fingers, and mouths twitch; and males have penile erections. Still, we are paralyzed, as indicated by atonia. This absence of muscle tone is the result of inhibitory signals sent from the brainstem to motor neurons in the spinal cord that command movement. In the sleep lab, atonia is recorded on an electromyogram as the absence

Question 60

Why do our eyes twitch in R sleep?

Answer 60

• such movements help to maintain blood flow in those parts of the body
• the brain is developing coordinated movements and tuning the neural circuits that support those movements—an activity especially important to infants, who have not yet developed full motor control

Question 61

How often do we dream?

Answer 61

Waking participants during R-sleep periods shows that everyone dreams, that we dream several times each night, and that dreams last longer as a sleep session progresses.

Question 62

Explain Freud’s dream theory?

Answer 62

Freud suggested that the function of dreams is the symbolic fulfillment of unconscious wishes—specifically sexual wishes. He further proposed that dreams have two levels of meaning. The manifest content of a dream is a series of often bizarre, loosely connected images and actions. The latent content of the dream contains its true meaning. Certain images, called phallic symbols, reflect sexual events.

Question 63

How did Freud interpret manifest symbols and latent content?

Answer 63

Freud provided a method for interpreting manifest symbols and reconstructing the latent content of dreams. For example, he pointed out that a dream usually begins with an incident from the previous day, incorporates childhood experiences, and includes ongoing unfulfilled wishes. He also identified several types of dreams, such as those that deal with childhood events, anxiety, and wish fulfillment. The latent content of the dream was important to Freud and other psychoanalysts in clinical practice because interpretation of dreams was proposed to offer insight into a patient’s problems.

Question 64

What did Jung believe?

Answer 64

Jung proposed that dreams allow the dreamer to relive the history of the human race—our “collective unconscious.”

Question 65

Describe activation synthesis theory

Answer 65

During a dream, the cortex is bombarded by signals from the brainstem, and these signals produce the pattern of waking EEG. In response to this excitation, some parts of the cortex generate images, actions, and emotions from personal memory stores. In the absence of external verification, these dream events are fragmented and bizarre and reveal nothing more than that the cortex is activated.

Hobson proposes, on the basis of PET imaging, that part of the frontal cortex is less active in dreaming than in waking. The frontal cortex controls working memory for recent events and attention. The dreamer thus cannot remember and link dream events as they take place because monitoring by the frontal cortex is required for these functions. On waking, the dreamer may attempt to come up with a story line for these fragmented meaningless images. In Hobson’s theory, dreams are personal in that memories and experiences are activated, but they have no intrinsic meaning.

Question 66

Describe coping theory

Answer 66

coping theory, is that enhanced performance is especially important for people whose environment typically includes dangerous events that constitute extreme threats to reproductive success. Dreams provide the dreamer with strategies for dealing with problems, even without the dreamer having to remember the dream. Revonsuo notes people seldom dream about reading, writing, and calculating, even if these behaviors occupy much of their day.