Chapter 3: Physiological Mechanisms of Arousal

PSY 338: Motivation

Arousal Theory

Behavior will change as we get more arousedContinuum of behavioral activation

very low ------------------ ---------------------- very high

coma sleep alert stressed rage

Arousal Theory

Yerkes-Dodson Law (1908)The law dictates that performance increases with physiological or mental arousal, but only up to a point

Task difficulty and type of task seem to be involved as illustrated by an Inverted-U functionThis Inverted-U hypothesis, often applied to sport, states that performance improves as arousal levels increase up to an optimum point, beyond which it deteriorates

See next slide

INVERTED-U HYPOTHESIS

LEVEL OF AROUSAL

PERFORMANCE

LEVEL

OPTIMUM LEVEL

Reticular Activating System (RAS)

Closely associated with the onset of arousal

Complex set of neurons and nuclei that extends throughout the brain stem and on up to the posterior hypothalamusHebb’s Theory (1955)

Sensory information serves two functions; cue function, arousal functioning

Mediated by RAS

Psychophysiological Measures

It appears we have several types of arousalBehavioral

Indicated by a responding organismAutonomic

Indicated by bodily functionsCortical

Evidenced by desynchronized, fast brain waves

Lacey (1967)Are independent but can occur together

Arousal Theory: Limitations

1. Lack of a strong relationship between measures of behavioral, cortical, and autonomic arousal

2. Lacey’s theory assumes different patterns of bodily responses, but studies have not found clear differences

3. Questions concerning the assumption that cortical arousal indicates a motivated or emotional state

4. Not clear if this cortical arousal is even effective in directing behavior

5. Questionable assumption that understanding of arousal is based only on physiological mechanisms

Environmental factors; history of the specific organism may also be necessary

SleepCircadian Rhythms

Our bodies are synchronized with the 24-hour cycle of day and night through this biological clock

This biological rhythym can be disrupted by things such as:Jet lag Radically altering your sleeping schedule from weekdays to weekends

The Stages of Sleep

Stages of sleep are distinguished by attaching electrodes to a person’s scalp and recording brain waves from an EEG (electroencephalograph) EEG measures patterns of activity in the brainNREM (Stages 1-4)REM (Stage 5)

Stage 1Very light sleep for about 10-15 minutesBreathing rate slows

Brain waves display theta waves (these are slower and more irregular)

Hypnagogic StateYou may experience fantastic images which are similar to

hallucinationsFor example, you may have a sensation of falling at which

moment your body may suddenly jerk, or of floating weightlessly, or you may have a vivid visual image

Myoclonus Jerk Short convulsion of the body which may be brought on when

your brain noticing your heart rate and breathing rate decreasing more rapidly than normal sends out a burst of electrical activity to your muscles

Stage 2

For the next 20 minutes we relax more deeply…Although, we can still be awakened without too much difficulty during this stage, you are now clearly asleep

Brain activity is characterized by sleep spindlesThese are periodic bursts of rapid, rhythmic brain activity

Stages 3 & 4Stage 3Very short phase – just a few minutes Gets us ready for deep sleep Large, slow delta waves are emitted approximately 20-50% of the timeOnce these waves are present more than 50% of the time we are considered to be in Stage 4 (deep sleep) Stage 4Occurs about 30-45 minutes after falling asleep; this deep sleep lasts for about 30 minutesTough to be awakened during this stage

Back down the ladder…About an hour after we fall asleep another strange phenomenon occurs…

Rather than continuing in deep slumber, we go back down the sleep ladder

We return to stage 3, then to stage 2 and then we enter the most intriguing sleep phase of all…

Aerinsky & Kleitman (1955)Discovered Rapid Eye Movement sleepCommonly referred to as REM sleep

Stage 5: REM sleep

For about 10:00, brain activity resembles Stage 1: Theta waves are seen (also beta and alpha waves)

But unlike Stage 1:HR increasesBreathing becomes more rapid and irregularLess snoring than in NREM stagesGenitals show signs of arousalErection in malesVaginal lubrication is possible in womenEvery 30 seconds or so your eyes dart around in a momentary burst of activity under your closed lids

Its called the “paradoxical sleep”

REM is often referred to as paradoxical because the increased eye movements, HR, respiration, and genital activity suggest arousal – yet the muscles are deeply relaxed and the sleeper is not easily awakened

Its our dream stage as well…

Aerinsky & Kleitman (1955) Correlated with reports of dreaming

Dement (1972) 80% of dreaming occurs in this stage Despite senselessness, dreams often contain some logic Very emotional and storylike Not like the fleeting images of stage 1

As the night wears on…

The sleep cycle repeats itself about every 90:00 with deep stage 4 sleep becoming briefer and then eventually disappearing and REM sleep getting progressively longer

Stages in a Typical Night’s Sleep

Hours of sleep

Minutesof Stage 4 and REM

1 2 3 4 5 6 7 80

10

15

20

25

5Decreasing Stage 4

Increasing REM

Why the rapid eye movements?Aerinsky & Kleitman (1955)Originally were not sure why this occurred except that it correlated with dreaming

Goodenough (1991)Reported that a consensus of several research studies provides evidence that the rapid eye movements are related to:

Amount of activity in dreams Dream bizarreness Intensity (emotionality) of dreams

DreamsTheoriesNeurocognitive Theory (Domhoff, 2001)

Based on research on brain injuries and sleep lab research this theory posits that dreaming is the result of the maturation and maintenance of a specific network of forebrain structures

Continuity principle: personal concerns during the day appear in one’s dreams Repetition principle: same characters and setting show up over and over again

(sometimes across decades)

Threat Simulation Theory (Revonsuo, 2000) Posits that the function of dreaming is to provide a virtual reality that simulates

threatening events in order to allow for the rehearsal of threat avoidance behaviors

There is an adaptive advantage to simulating real-life threatening confrontations; such simulations could improve the ability to perceive and avoid threats during wakefulness

DreamsTheoriesFranklin & Zaphur (2005)

Extended Revonsuo’s theoryVirtual rehearsal mechanism – helps human cognition

Sleep Deprivation

Problems:Chronically fatiguedDiminished immunity to diseaseSlight hand tremorIrritabilityOccasional moments of inattention or misperceptions on monotonous tasks

Example: Cross-country drivingNote: on highly motivated tasks, sleep deprivation has little effect

Dream (REM) Deprivation

REM ReboundWhen dream-deprived participants are finally allowed to sleep without interruption, they dream much more than normalREM periods are rebounding from their imposed low level

Dream (REM) Deprivation

Drug MisuseSome drugs if taken beyond recommended levels can suppress REM sleepWithdrawal symptoms lead to increased dreaming with vivid nightmares

Randy Gardner 1965 - 17 year-old who

made it into Guinness Book of World Records by staying awake for 11 days (264 hours)

During the final night, he beat one of the researchers 100 straight times in a pinball game

Dement (1965)

Stanford University researchers reported that Gardner had few ill effects during the experimentSome STM problems to go along with moodinessGood health afterwards

Sleep Deprivation

“no more all-nighters”

Randy Gardner today

Note: In 2010, interview he said he was in overall good health; however, suffers from bouts of insomnia

Gardner’s record finally broken in 2007?

Tony Wright, a 42-year-old horticulturalist

Apparently, the effects were more severe for this guy…

In 1959, a New York disc jockey, Peter Tripp, attempted a publicity stunt by staying awake for 201 hours

After three days, he began to hallucinate and turned paranoid

It was almost as though his sleep-deprivation was allowing dream images to break into his waking consciousness

Physiology of Sleep

Brainstem regions that promote NREM sleepVentrolateral preoptic area appears to be crucial for delta wave sleep

Brainstem regions that promote REM sleepSeveral areas located in the upper portion of the pons appears to be crucial for REM sleep; complex interaction of several cells within this area

Neurotransmitters that promote sleepGABA

Inhibits the activity of several areas of the brain linked to arousalActivity in these areas limits REM sleep

Neurotransmitters that promote arousal

AcetylcholineIncreases arousal; blockers decrease arousal

NorepinephrineHigh during wakefulness; low during sleep Important for vigilance

SerotoninMost active when awake; decrease during sleep Facilitates maintaining ongoing activities; suppresses sensory information that may interrupt these activities

HistamineConnections of histamine-producing neurons to the cortex increase arousal directly; high during waking and lower during sleep

OrexinCells that produce this neurotransmitter respond primarily when rats are alert and engaged in activity

Brainstem Neural Flip-Flops

Two “flip-flop” mechanisms (switch) seem to be involved with our sleep:

1.When one system of cells is active it inhibits cells of the other system; depending on which system is active causes us to be awake or asleep

2.A second switch seems to control transitions from NREM to REM

Possible functions of sleep

Restorative FunctionNREM sleep appears to help restore body and brain for the next day’s activitiesREM sleep may help with attention and emotion; coping with stress

Organization of the brainREM sleep can begin three months before birth; could be an internal source of stimulation that organizes our brains properly

Possible functions of sleep

Programming DeviceNew material learned during waking is seen as being incorporated into and changing the existing organization of the brainREM sleep: “self-programming computer”

Consolidation of MemoriesSTM LTM

Storage of Complex Associative InformationREM helps us with recall of this information

Stress

Selye (1973)Nonspecific response to demandMovement away from optimal body functioning (homeostasis)

Systemic StressInvolves a challenge related to our body; endocrine system activity is activated

Psychological StressWorry, anxiety, etc.

Types of Psychological Stressors

CatastrophesSignificant Life ChangesDaily Hassles

Scarring Effects of Natural Disasters

Krug et al. (1998)These researchers analyzed counties that had experienced disasters Before/after research revealed some alarming numbers

0

10

20

30

40

50

60

70

Increase in

Suicide Rate

Floods Hurricances Earthquakes

Type of Natural Disaster

Significant Life Changes

Change itself may cause stress by forcing us to adapt to new circumstancesIs change, positive or negative, necessarily harmful?No support that positive “stressors” are as harmful as negative stressors

Impact of change depends on person and how change is interpreted

The Hassles of Everyday Life

Most common source of stress arises from the daily hassles that irritate usEx: Environmental factors

“Microstressors” place a constant strain on usThe accumulation of daily hassles contributes more to illness than do major life events

Dormitory LifeBaum & Valins (1977)

These researchers compared two layouts of dormitory in university residences

Traditional dorms appear to be more stressful than newer suite style

They demolished this traditional residence hall

In one case, a 26 floor, 1,300 student residence, Sander Hall, was demolished at the University of Cincinnati in 1991 because of persistent problems of violence and vandalism

Sander Hall

This is usually not a good idea…

Karlin et al. (1979)Students who are accommodated 3 to a room intended for 2 suffer less contentment and lower grades

Is noise stressful?

Research indicates that living in a busy city, near a highway, airport, etc. can have detrimental effects

Shea Stadium (Queens, NYC)Right in the flight path to LaGuardia Airport

Click on picture for article

General Adaptation Syndrome (GAS)Selye (1976)GAS model illustrates the effects of stressSelye felt that the body’s adaptive response to stress was very general – like a burglar alarm that would sound off no matter what intrudedHis model has three overlapping stages - alarm, resistance, and exhaustion

Design of Studies on StressRetrospective StudiesIndividuals are asked to indicate when illnesses and life changes had occurred in their life

Prospective StudiesIndividuals supply information about recent life changes Health is then monitored by individualFollow-up interview about changes in healthAttempt to see if changes in ones life can predict their health

Buffering the effects of stressors

Hardiness Personality Individuals exhibit three characteristics:

CommitmentChallengeControl

Criticisms of Hardiness ConceptValidity of these measuring tools has been questioned

Other buffers of stress

Social Support TheoryThe helpful coping resources provided by friends and other peopleHas therapeutic effects on both our psychological and physical healthSocial support and contact related to longevityF > M

House et al. (1988)Some indications social support might help men more than women

Other buffers of stress

Explanatory styleOptimistic explanatory style is a generalized tendency to expect positive outcomes; appears related to better outcomes

These individuals more likely to attribute bad events as: unstable, specific, and external

Pessimistic explanatory style is a generalized tendency to expect negative outcomes; appears related to poor outcomes

These individuals more likely to attribute bad events as: stable, global, and internal

Other buffers of stress

Expressive styleHumor is good; weeping not so goodMight be an interaction with explanatory style

Health Psychology

The application of psychology to the promotion of physical health and the prevention and treatment of illnessModification of one’s lifestyle, outlook, and behavior can lessen risk of such things as heart disease, cancer, strokes, accidents, AIDS, etc.

Health Psychology

Behavior can influence health in several way:Biological Changes

As a result of one’s behaviors; emotionsBehavioral Risk

Enhancing our chances of staying healthy or not; diet, exercise, smoking, drinking, etc.

Illness Behaviors Seeking medical care or not; compliance with doctor’s orders Females are better at this

See next slide

Why men don’t live as long…Williams (2003)

Work conditionsDangerous jobs F < MJob-related stressors F < M

Personal health practicesSmoking: F < MDrinking: F < MFeel high-risk activities will not affect them: F < M

Social supportF > M

Use of health care servicesF > M

Adherence to medical regimensF > M

Psychoneuroimmunology

Bidirectional communication between the brain and the immune system and that the immune system influences both the endocrine system and behavior Conditioning of immune responses

Changes in the immune system as a result of learning can influence the body’s reactions

Conditioning of immune responses

Ader & Cohen (1975); Ader (2001)Rats drank a saccharin solution immediately before the injection of cyclophosphamide, an immunosuppressive drug that also has aversive gastrointestinal side effects

Following this pairing, rats avoided drinking the saccharin solution

Results related to immune functioningThe saccharin CS also developed capacity to suppress immune functioning as a CR

Psychosocial factors & the immune system

Strong evidence that psychological changes can modify various aspects of the reaction of the immune systemStrong correlation between stress and immunity

Segerstrom & Miller (2004)Acute stress can have adaptive or maladaptive effect on immune systemChronic stress always leads to maladaptive functioning; immunosuppression

Placebo EffectsPlacebo is an inert substance that people report has an effect

on themPrice et al. (2008)

Social interactions such as verbal suggestions can influence a placebo response

Prior experiences to a placebo has been a factor in participants’ future placebo response

For example, if pain was lessened by first administration to a placebo

Scott et al. (2007)Researchers have also found that the fake pain-killing

chemicals actually caused the brain to dispense real pain-killing opiates in some participants, thus relieving the pain that was initially felt

Sexual ArousalMasters & Johnson (1966)William Howell Masters was a gynecologist, and Virginia Johnson was a psychology researcherThey teamed up to study human sexualityThey observed sexual activity in a laboratory settingThey developed tools and techniques for accurately measuring the physical responses of 700 men and women during masturbation and intercourseThey determined that humans have four specific stages of sexual response See next slide

Sexual Response Cycle EXCITEMENT PHASE

Genital areas become engorgedHR, BP, breathing rates increasePLATEAU PHASEHR, BP, breathing rates increase furtherORGASMIC PHASEMuscle contractions all over the bodyHR, BP, breathing rates increase even furtherFeelings of pleasure apparently the same for both sexesRESOLUTION PHASEBody gradually returns to unaroused stateMales enter a refractory period in which he is incapable of another orgasm (this varies in time depending on the individual from a few minutes to over a day)Females refractory period is not long (if at all) as often they can reach orgasm again if restimulated

Masters & Johnson

CreditsSome slides prepared with the help of the following websites:

• ftp://ftp.amberton.edu/_.../Lectures/Motivation%20Lecture%2...

• www.southalabama.edu/psychology/docs/.../310-8-student.ppt