Unit 4 - Biological Psychology

2.1 Interaction of Heredity

and Environment

Evolutionary Psychology

2.2 Endocrine System

2.3 Nervous System

2.3 Neurons

2.4 Neural Firing

2.5 Neurotransmitters

2.6 The Brain

2.7 Imaging

2.8 Drugs and Addiction

2.9 Sleep and Dreams

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2.1 Interaction of Heredity and Environment

Monozygotic Twins*

Dizygotic Twins*

Twin Studies*

Adoption Studies*

Heritability*

Gene Environment Interaction*

Evolutionary Psychology

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Genes: Our Codes for Life

Chromosomes containing DNA (deoxyribonucleic acid) are situated in the nucleus of a cell.

Genes: Our Codes for Life

Segments within DNA consist of genes that make proteins to determine our development.

Genome

Genome is the set of complete instructions for making an organism, containing all the genes in that organism. Thus, the human genome makes us human, and the genome for drosophila makes it a common house fly.

Genes 101

• Dominant Gene – Member of a gene pair that controls the appearance of a certain trait.
• Recessive Gene - Member of a gene pair that controls the appearance of a certain trait only if it is with another recessive gene.

Genes 101 cont’d

• Polygenic Inheritance – Process by which several genes interact to produce a certain trait; responsible for our most important traits.

Twin Biology

Studying the effects of heredity and environment on two sets of twins, identical and fraternal, has come in handy.

Mz vs. Dz Twins

The odds of having identical twins is about 3 in 1,000, whereas the birthrate for all twins is about 32.2 in 1,000.

Most (60–70%) monozygotic twins share a placenta but have separate amniotic sacs.

A small number (1-2%) of monozygotic twins share a placenta and amniotic sac.

Fraternal twins each have their own placenta and own amniotic sac.

How do psychologists use twins to study the causes of human behavior?

• If MZ twin sets share more similarity in a trait than DZ twins, then the trait has a genetic component. (Just normal siblings will show even less similarity.)

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How do MZ and DZ twin studies help �us understand nature and nurture?

A person whose identical twin has autism spectrum disorder has about a 3 in 4 risk of being similarly diagnosed. If the affected twin is fraternal, the

co-twin has about a 1 in 3 risk.

(Ronald & Hoekstra, 2011).

Identical twins are much more alike in extraversion (outgoingness) and neuroticism (emotional instability)

than are fraternal twins.

(Kandler, 2011; Laceulle et al., 2011; Loehlin, 2012).

Drinking and driving convictions are 12 times greater

among those who have an identical twin than

those with a fraternal twin with such a conviction.

(Beaver & Barnes, 2012).

How do psychologists use twins to study the causes of human behavior?

• If MZ twin sets, who are raised apart (so they don’t have the same environment growing up), still show those similarities then we can say that genetics have a role in that trait.

What do twins reared apart tell us about heredity and environment?

Thomas Bouchard and his colleagues located and

studied 74 pairs of identical twins raised apart. They found similarities of tastes and physical attributes, personality, abilities, attitudes, interests, and even fears.

Jim Lewis

• Middle Class
• Wife named Betty – left her love notes
• Son named James Alan
• Dog named Toy
• Woodworking hobby
• Circular white bench around a tree in his yard.
• Chain Smoker
• Bit his fingernails
• Drove a Chevy, watched stock car racing, and drank Miller-Lite
• Suffered from High Blood Pressure and Migraines

Jim Springer

• Calls his 37 year separated twin in February 1980
• Everything down to the dog’s name is the same (except sons James Allan vs. James Alan)
• When played their voices, they would mistake themselves for their twin
• They are the first in Thomas Bouchard’s twin study
• Bouchard studied 80 pairs of identical twins reared apart
• Statistical issues…

Separated Twins

Critics of separated twin studies note that such similarities can be found between strangers.

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Researchers point out that differences between DZ twins are greater than MZ twins.

Adoption Studies

For some traits, Adoption suggest that adoptees (who are biologically unrelated to their adopted family) tend to be more similar to their biological parents than their adoptive parents and adopted siblings.

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Those traits have a genetic component

How do adoption studies help us �understand nature and nurture?

The stunning finding from studies of hundreds of adoptive families is that, apart from identical twins, people who grow up together, whether biologically related or not, do not much resemble one another in personality.

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Two adopted children raised in the same home are no more likely to share personality traits with each other than with the child down the block.

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The environment shared by a family’s children has virtually no discernible impact on their personalities

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(McGue & Bouchard, 1998; Plomin, 2011; Rowe, 1990).

Parenting

Parenting does have an effect on biologically related and unrelated children.

“Mom may be holding a full house while Dad has a straight flush, yet when junior gets a random half of each of their cards his poker hand may be a loser.” David Lykken (2001)

Heritability

Measure of how much the differences in people's traits can be attributed to differences in genes

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15 inch difference - how much of that is due to differences in genes?

Heritability

• Because heritability is a proportion, its numerical value will range from 0.0 (genes do not contribute at all to phenotypic individual differences) to 1.0 (genes are the only reason for individual differences).
• For human behavior, almost all estimates of heritability are in the moderate range of .30 to .60.

Heritability

Heritability estimates range from zero to one.

A heritability close to 0 indicates that almost all of the variability in a trait among people is due to environmental factors, with very little influence from genetic differences.

Characteristics such as language spoken or political preference have heritability of zero because they are not under genetic control.

A heritability close to 1.0 indicates that almost all of the variability in a trait comes from genetic differences, very little contribution from environment.

Many disorders that are caused by mutations in single genes, such as phenylketonuria (PKU), have high heritability.

Heritability

Most complex human traits such as intelligence and multifactorial diseases, have a heritability somewhere in the middle, suggesting that their variability is due to a combination of genetic and environmental factors.

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How do behavior geneticists �estimate the heritability of a trait?

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Many personality traits are ~40% heritable.

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Intelligence is ~60% heritable.

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Height is ~90% heritable.

What does “intelligence is about 60% heritable” mean…and NOT mean?

What

it means.

Genetic influence explains

about 60% of the observed differences in intelligence among people.

What it doesn’t mean.

Your intelligence is 60% genetic.

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How do similar environments �impact heritability?

If all schools were of uniform quality,

all families equally loving, and

all neighborhoods equally healthy,

then

heritability would increase

(because differences due to environment

would decrease).

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So any difference we noticed between two students would be due more to their genes than their environment.

Environmentability is rather the opposite

• It is the extent to which the differences among people are attributable to the environment.
• If the heritability of most human behaviors is in the range of .30 to .60, then the environmentability of most human behaviors will be in the range of .40 to .70.

What can you say?

• Heritability and environmentability are population concepts. They tell us nothing about an individual.
• A heritability of .40 informs us that, on average, about 40% of the individual differences that we observe in, say, shyness may in some way be attributable to genetic individual difference.
• It does NOT mean that 40% of any person's shyness is due to his/her genes and the other 60% is due to his/her environment.

Gene-Environment Interaction

Genes can influence traits which affect responses, and environment can affect gene activity.

A genetic predisposition that makes a child restless and hyperactive evokes an angry response from his parents. A stressful environment can trigger genes to manufacture neurotransmitters leading to depression.

Gene-Environment Interaction

Genes and environment affect our traits individually, but more important are their interactive effects.

People respond differently to

Rowan Atkinson (Mr. Bean) than Chris Hemsworth

Not Nature vs. Nurture

• Gene-Environment Interaction is Nature AND Nurture

What is epigenetics?

The study of environmental influences

on gene expression that occur

without a DNA change.

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When we break down the word,

“epi” means above or in addition to.

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So (epi) genetics studies how an individual’s lifestyle, environment, choices, etc. can directly interact with the genome.

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How does epigenetics influence gene expression?

Beginning in the womb,

life experiences lay down

epigenetic marks—often

organic methyl molecules—that can affect the expression of any gene in the DNA segment

they affect.

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(Research from Champagne, 2010.)

What are some examples of epigenetics research?

Researchers have found the effects of childhood trauma, poverty, or malnutrition may last a lifetime.

Nugent et al., 2016; Peter et al., 2016; Swartz et al., 2016)

Conceivably, your health and well-being could be affected by stresses or pollutants that your parent or even grandparent experienced.

(McCarrey, 2015; Skinner, 2014; Yehuda et al., 2016)

Researchers question why only one member of an identical twin pair may develop a genetically influenced mental disorder.

(Spector, 2012)

Evolutionary Psychology

Natural Selection

• Natural selection is an evolutionary process through which adaptive traits are passed on to ongoing generations because these traits help animals survive and reproduce.
• According to natural selection, those organisms that are best adapted to their environment are most likely to survive and reproduce.
• Thus their genes are more likely to get passed along.

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Evolutionary Psychology

• According to evolutionary psychologists, all organisms, including humans, are "gene-producing machines" with the basic motivation of perpetuating their own genetic pool. In short, our genes predispose us to act in ways that enhance their chances of surviving and spreading. This fundamental motive underlies all our behavior.
• Evolutionary Psychology attempts to explain common behavior BY LOOKING AT WHAT WAS HELPFUL reproduce or survive

Problems Faced by Ancestral Humans

• Problems of Survival: Getting the organism to a point where it is capable of reproducing.
• Problems of Mating: Selecting, attracting and retaining a mate long enough to reproduce.
• Problems of Parenting: Helping offspring survive long enough that they are capable of reproducing.
• Problems of aiding genetic relatives: Tasks relevant to assisting non-descendent kin.

Human Survival Problems

• Food selection: The most general problem in food selection is how to obtain adequate amounts of calories and essential vitamins.
• However, we must also avoid poisoning ourselves.
• Plants have adapted toxins that help reduce the odds that the plant will be eaten.
• Hypothesis: humans have evolved taste preferences to avoid toxic materials.
• How do we test this?

Taste Aversions

• Evidence suggests that the materials that smell and taste bad to humans are also the materials that are potentially harmful to us.
• Broccoli and brussel sprouts contain allylisothiocynate which can be toxic in children (Nesse & Williams 1994)
• We have adaptive mechanisms for removing harmful materials from our body.
• Vomiting.

Morning Sickness

• The percentage of women who experience morning sickness has been reported to be anywhere from 75 – 89%. However, estimates suggest that the actual % is near 100.
• Hypothesis: Morning sickness is an adaptation to avoid consuming teratogens during the critical period in the development of the fetus.
• Evidence: The foods that pregnant women report to be most nauseating are correlated with high levels of toxins.
• Evidence: Morning sickness occurs at the same time that the fetus is most vulnerable to toxins.
• Evidence: Morning sickness decrease around the same time that the period critical for fetal development has passed.

Morning Sickness

• Remember, an adaptation must confer an increase in fitness.
• Hypothesis: Women who do not experience morning sickness will be more likely to have problems during their pregnancy.
• Evidence: Women who do not experience M.S. are 3 times more likely to experience a spontaneous miscarriage (Profet, 1992)

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Human Fears

• Fear can be viewed as an adaptive response to avoid situations that may lead to injury or death.
• Have humans evolved adaptive fear responses to specific stimuli? Or do humans learn fear responses through conditioning?

Common Fears and Phobias

• The majority of reported fears and phobias involve:
• Spatial stimuli: heights, confined spaces
• Specific animals: snakes, bats, spiders
• The dark
• Public speaking
• There have been very few reported phobias of electricity, cars, busses, power tools, wood stoves, lawn mowers, mountain bikes, X-ray machines, etc…

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Prepared Fears

• Mineka (1983) observed that rhesus monkeys raised in captivity did not show a fear response when confronted with a snake.
• If these monkeys were shown videos of other monkeys displaying fear in the presence of a snake the subject monkeys quickly acquired the same fear response. (same for crocodile)
• If captive raised monkeys were shown a video of monkeys displaying fear in the presence of a pot of flowers the subject monkeys did not acquire a fear response to flower pots. (same for rabbit)

Prepared Fears in Humans

• Human subjects more quickly form associations between images of snakes or spiders and a mild electric shock than between images of electrical cords or mushrooms and a mild electric shock.
• They also report that the shocks that occur after images of snakes and spiders are more painful!

Problems of Survival

• Language goes the longest way to solve this.
• All children acquire language without specific instruction
• This happens in all cultures at about the same age and in the same stages
• The nature of all human languages is the same (nouns, verbs, subjects, questions etc.)
• Conclusion: Our brains are hardwired for language. Even identified a gene (FOXP2) believed to be linked to this.

Problems of Parenting

A number of human traits have been identified as a result of pressures afforded by natural selection.

Stranger Anxiety:

Why do infants fear strangers when they become mobile?

Parental Love

Why are most parents so passionately devoted to their children?

What follows is based on reproduction

• It is going to inherently be about creating a child and not sex for pleasure or finding companionship
• It will be heteronormative and since much of the research is still done with a binary bias, it will be very cisgendered
• This is specifically about evolutionary psychology.

Cross-Cultural Surveys.

• In a survey of 37 cultures involving more than 10,000 participants, Buss (1989) tested predictions concerning sex differences in mate preferences.
• Participants were asked to rate the importance of each of 18 characteristics in a potential mate using a 4-point scale.
• 'good companion', 'considerate', 'honest', 'affectionate', 'dependable‘. 'fond of children', ‘good earning capacity', ‘industrious' , ‘intelligent’, ‘good sense of humour’ 'physically attractive', 'good looking', 'good cook', and 'frugal'.

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“I have been noticing you around campus and I find you to be very attractive. Would you go to bed with me tonight?

• Russell Clark and Elaine Hatfield (1978)
• Confederates “Average-looking student research assistants”
• Women = 0% affirmative responses
• Men = 75% affirmative responses
• Some men replied “Why do we have to wait until tonight?”
• Repeated in 1982 and in the late 1980s with similar results. (50-75% of the men said yes.)

Operational definitions? Confounding Variables? Replication?

Sex Differences in Mating Preferences

Males and females, to a large extent, behave and think similarly. Differences in sexual behavior may arise in regards to reproductive behaviors.

• Due to the reproductive reality, it would seem most adaptive for women to find a mate that gives the best genes, resources, and long-term parental care.
• Males can pass on as many genes as they can find willing partners.

Have these genetically motivated ‘mating preferences’ played a role in the formation of harmful gender roles in our society?

2.2 The Endocrine System

Hormones

Pituitary Gland

Pineal Gland

Adrenal Gland

Gonads

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What is the endocrine system?

the body’s “slow”

chemical communication system;

a set of glands that secrete

hormones into the bloodstream

What is the difference between the nervous system and the endocrine system?

nervous system

• Neurons release neurotransmitters

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• Neurotransmitters move across synapses

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• Neural transmission is nano-fast

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• “text message”

endocrine system

• Glands secrete hormones

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• Hormones move through the bloodstream

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• Hormonal secretion is slower

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• “email”

Hormones are _____ released into the bloodstream.

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1. Neurons
2. Myelin
3. action potentials
4. electrical messengers
5. chemical messengers

3. What Would You Answer?

What are the glands of the endocrine system?

The Endocrine System

• Controlled by the Hypothalamus (write down 4Fs for later)
• Helps coordinate and integrate complex psychological reactions
• Endocrine glands secrete hormones into the bloodstream. It is much slower than the nervous system.
• Hormones are chemical substances (similar in function to neurotransmitters) that help regulate bodily activities.

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What is the pituitary gland?

The pituitary gland is the endocrine system’s most influential gland.

The hypothalamus directs the pituitary gland to regulate growth and control other endocrine glands.

The hypothalamus is part of both the CNS and the endocrine system.

Pituitary gland

• The pituitary gland is the “master gland” of the endocrine system.
• It is controlled through the nervous system by the nearby brain area--the hypothalamus.
• The pituitary gland produces hormones that regulate other glands such as the thyroid.

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Pituitary Gland

• Influences blood pressure, thirst, contractions of the uterus during childbirth, sexual behavior and interest, body growth etc.
• It also produces human growth hormone (hGH) (especially during sleep) and oxytocin, the “bonding” hormone.

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Pineal gland

• Secretes melatonin which regulates the sleep-wake cycle
• Disturbances in melatonin are responsible for “jet lag”

Thyroid gland

• Secretes hormones (primarily thyroxin) that control metabolism
• How alert and energetic and how much weight you carry
• Overactive Thyroid can mean insomnia, reduced attention span, agitation
• Too little thyroxin can mean feeling constantly tired

What are the adrenal glands?

When the sympathetic nervous system is activated (during a fight, flight, or freeze event), the adrenal glands release epinephrine and norepinephrine (adrenaline and noradrenaline) to energize the body.

Adrenal Glands

• Amygdala warns the hypothalamus of a threat which then triggers the adrenal glands to release epinephrine (adrenaline) to energize the body during a fight or flight response.
• Causes increased blood glucose, fatty acids and energy production within the body's cells.
• increased heart rate, contracted blood vessels and dilated air passages.

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Ultimately, these changes allow more blood to get to the muscles and get more oxygen to the lungs quickly—so your physical performance improves and you're primed to either flee from danger or defend yourself.

Fun fact! Norepinephrine (noradrenaline) is both a hormone and a neurotransmitter.

Epinephrine (adrenaline) energizes the body, but norepinephrine (noradrenaline) is released in the PNS to calm the body.

Pancreas

• Regulates blood-sugar levels
• Secretes insulin and glucagon
• Husbands and wives reported being most unhappy with their spouses when their blood-sugar levels were lowest, usually at night, according to research released today in the Proceedings of the National Academy of Sciences. Missing a meal, dieting or just being hungry may be the reason, researchers said.

Gonads

• Ovaries and testes secrete estrogens and androgens (testosterone)
• These hormones play a role in development, aggression, sexual drive and brain growth during prenatal development
• Testosterone - testosterone levels are higher in individuals with aggressive behavior
• Testosterone activates the subcortical areas of the brain to produce aggression, while cortisol and serotonin act antagonistically with testosterone to reduce its effects.

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2.3 Part 1 - Overview of the Nervous System

Central nervous system

Peripheral nervous system

Somatic nervous system

Autonomic nervous system

Sympathetic nervous system

Parasympathetic nervous system

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Types of Neurons

Sensory/Afferent Neurons

Motor/Efferent Neurons

Interneurons

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What is the nervous system?

the body’s

speedy, electrochemical

communication network, consisting

of all the nerve cells of the peripheral

and central nervous systems

What are nerves?

bundled axons of many neurons that

form neural cables connecting

the central nervous system with

muscles, glands, and sense organs.

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For example, the optic nerve bundles a million axons into a single cable carrying the messages from the eye to the brain

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What are the three types of neurons?

There are three types of neurons: sensory (afferent), motor(efferent) and interneurons.

How are sensory and motor neurons different?

sensory neurons

contain afferent nerve fibers

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carry information from the sense organs to the CNS

motor neurons

contain efferent neurons

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carry messages from the CNS to the muscles and glands

Interneurons

• any neuron that acts as an intermediary in passing signals between two other neurons.
• Interneurons do not have motor or sensory functions; they just act to pass on information.
• About 20-30% of brain
• Also located in the spinal column

What is the Central Nervous System (CNS) and what does it do?

The CNS is made up of the brain and spinal cord.

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The CNS is the decision maker… it is responsible for coordinating incoming sensory messages and outgoing motor messages.

What is the Peripheral Nervous System (PNS) and what does it do?

The PNS is made up of sensory and motor neurons.

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The PNS connects the body to the CNS by gathering information from the senses and transmitting messages from the CNS.

What are the two parts of the �peripheral nervous system?

somatic

controls the body’s

skeletal muscles

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also called the skeletal nervous system

autonomic

controls the glands

and the muscles of the internal organs

(such as the heart)

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operates automatically

How is the autonomic division �further broken down?

sympathetic nervous system

arouses the body, mobilizing its energy

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fight, flight or freeze

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The gas pedal of a car.

parasympathetic nervous system

calms the body,

conserving its energy

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rest or digest

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The brake pedal of a car.

The sympathetic nervous system…

accelerates heartbeat,

raise blood pressure,

slows digestion, raises blood sugar, and

cools the body

SNS = Evolutionary Byproduct

How Stuff Works - SNS

The amygdala (fear center of the brain) sends a distress signal

The hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands.

These glands respond by pumping the hormone adrenaline (also known as epinephrine) into the bloodstream.

As adrenaline circulates through the body, it brings on a number of physiological changes.

• The heart beats faster than normal, pushing blood to the muscles, heart, and other vital organs.
• Pulse rate and blood pressure go up.
• The person undergoing these changes also starts to breathe more rapidly. Small airways in the lungs open wide. This way, the lungs can take in as much oxygen as possible with each breath. Extra oxygen is sent to the brain, increasing alertness.
• Sight becomes shaper as the pupils dialate
• Meanwhile, adrenaline triggers the release of blood sugar (glucose) and fats from temporary storage sites in the body. These nutrients flood into the bloodstream, supplying energy to all parts of the body.

All of these changes happen so quickly that people aren't aware of them. In fact, the wiring is so efficient that the amygdala and hypothalamus start this cascade even before the brain's visual centers have had a chance to fully process what is happening. That's why people are able to jump out of the path of an oncoming car even before they think about what they are doing.

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How Stuff Works - SNS

As the initial surge of epinephrine subsides, the hypothalamus activates the second component of the stress response system — known as the HPA axis. This network consists of the Hypothalamus, the Pituitary gland, and the Adrenal glands.

The HPA axis relies on a series of hormonal signals to keep the sympathetic nervous system — the "gas pedal" — pressed down. If the brain continues to perceive something as dangerous, the hypothalamus releases corticotropin-releasing hormone (CRH), which travels to the pituitary gland, triggering the release of adrenocorticotropic hormone (ACTH). This hormone travels to the adrenal glands, prompting them to release cortisol. The body thus stays revved up and on high alert. When the threat passes, cortisol levels fall. The parasympathetic nervous system — the "brake" — then dampens the stress response.

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The parasympathetic nervous system…

decelerates heartbeat,

lowers blood pressure,

stimulates digestion, processes waste, and

calms the body

How do the two parts of the �central nervous system function?

brain

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Comprised of the cortex and subcortical structures carrying out various functions

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Nerves arranged into neural networks

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Like people grouping in cities

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spinal cord

2-way connection between PNS and brain

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Oversees the sensory and motor pathways of reflexes.

How does a reflex occur?

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Sense receptors in the skin send signals up through the spinal cord via sensory (afferent) neurons.

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Interneurons in the spinal cord receive the information from the sensory neurons and send signals back through motor neurons.

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Motor (efferent) neurons connect to muscles in the body and direct movement.

How does a simple reflex occur?

A simple reflex ... like that to pain… occurs only in the spinal cord before information reaches the brain.

2.3 Part 2 - Overview of the Neuron

Parts of the Neuron

Receptor Sites

Dendrites

Soma (Cell Body)

Axon

Myelin Sheath

Terminal Buttons

Vesicles

Synapse

Glial Cells

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What is a neuron?

A neuron is a nerve cell that is the basic building block of the nervous system.

What are the parts of a neuron?

What is the cell body (soma)?

the part of the neuron that contains the nucleus, the cell’s life-support center

What are the dendrites?

bushy, branching extensions that

RECEIVE

messages from other neurons

What is the axon?

Attached to the soma, this

passes ELECTRIC messages from the cell body to the axon terminals.

What is the myelin sheath?

the

fatty tissue layer segmentally

encasing the axons of some

neurons; increases transmission speed and provides insulation

What is myelin and why is it important?

• At birth, babies have not yet myelinated the axons of their neurons.

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• The development of the myelin sheath, not complete until around age 25, is crucial to behavior, movement and thought.

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• Deterioration of the myelin sheath can lead to motor impairments, such as multiple sclerosis.

What are the terminal branches?

The ends of the axon containing terminal buttons which hold synaptic vesicles that store neurotransmitters.

What are glial cells?

cells that support,

nourish, and protect neurons;

they also play a role in learning,

thinking, and memory

Neurons are like queen bees;

on their own they cannot feed or sheathe themselves.

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Glial cells are

worker bees;

they provide nutrients and insulating myelin, guide neural connections, and

mop up ions and neurotransmitters.

What is a synapse?

the junction

between the axon tip of the sending

neuron and the dendrite or cell

body of the receiving neuron

The tiny gap at this junction is called the synaptic gap or synaptic cleft.

What is a neurotransmitter?

chemical

messengers

that travel

across the

synapse and bind to receptor sites

on the receiving neuron

2.4 Neural Firing

Resting Potential(Polarization)

Threshold of Excitation

All-or-none Law

Action Potential (Depolarization)

Repolarization

Absolute and Relative Refractory Periods

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Before a neuron fires it is at Resting Potential

• Resting Potential
• Nothing is happening. The gates of the axon are closed.
• Positive ions are on the outside with the negative ions on the inside of the cell.
• “Negative Ions inside the Neuron is Natural”

What is the resting state of an axon?

Prior to beginning the action potential, the outside of an axon’s membrane has mostly positively charged sodium (Na⁺) ions and the interior contains negatively charged proteins and a small amount of positively charged potassium (K⁺) ions.

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This creates a slightly negative charge and at this point, the neuron is said to be in the

resting state, or polarized.

How is a neural impulse generated?

If the combined received chemical signals exceed a minimum threshold, the neuron fires, transmitting an

electrical impulse (the action potential)

down its axon by means of a

chemistry-to-electricity process.

What is a threshold?

The level of stimulation

required to trigger a neural impulse.

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Neurotransmitters received by the dendrites build up to initiate the action potential.

What is the all-or-none response?

More stimulation does not produce a more intense neural transmission.

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The neuron’s reaction is an all-or-none response. Neural firing happens at full response or not at all.

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Like guns, neurons either fire or they don’t. Squeezing a trigger harder won’t make a bullet go faster.

The Neural Impulse

• All-or-None Law
• A neuron either fires or it does not
• When it does fire, it will always produce an impulse of the same strength
• Intensity of a stimulus is seen by the frequency of action potentials

frequency

frequency

frequency

Incoming neurotransmitters can be �excitatory or inhibitory.

excitatory signal

Like the gas pedal

on the car.

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Excitatory neurotransmitter signals trigger action.

inhibitory signal

Like the brake pedal

on the car.

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Inhibitory neurotransmitter signals depress action.

When the excitatory impulses outnumber the inhibitory impulses, the threshold has been reached and an action potential occurs.

What does it mean that an axon membrane is selectively permeable?

The membrane contains voltage gated ion channels that either open to

allow ion exchange (depolarization) or

close to prevent ion exchange (polarization).

Neural Firing!

• Action Potential
• a brief electrical charge that travels down an axon
• Also called neural impulse or nerve firing or depolarization
• generated by the movement of positively charged ions into the axon.
• This process starts due to stimulation of the receptor sites for the neuron that is firing

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Neural Firing!

• Polarization
• When the inside of the Neuron is negatively charged relative to the outside
• Resting potential
• Depolarization
• When the electrical charge of a cell moves toward zero
• Action potential

What are the steps in an action potential?

Step 1:

The semipermeable axon opens its gates once the threshold is met.

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Na⁺ ions flood in through the channels.

Why do Na⁺ ions rush in?

Since the inside of the membrane is slightly more negative, the Na⁺ ions try to balance the charge.

This causes a slight depolarization.

What is the next step in an action potential?

Step 2

The depolarization changes the electrical charge of the next part

of the axon.

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Gates in this second area now open, allowing even more Na+ ions to flow in.

How do K⁺ ions move out?

At the same time, gates open in the first part of the axon allowing K⁺ ions to flow out.

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This repolarizes that section of the axon.

What happens next?

The sodium/potassium pump continues to depolarize new sections of the axon and repolarize the previous sections.

How does the impulse move?

The influx of the positive ions is the neural impulse.

​

The impulse moves down the axon like dominos falling one after the other.

What happens after the action potential moves to the end of the neuron??

​

Neurons need short breaks.

​

During a resting pause called

the refractory period,

subsequent action potentials cannot occur

until the axon returns to

its resting state.

​

Then the neuron can fire again.

​

Let’s review three key terms in the process…

Polarization: the resting state of the neuron, charge is more positive outside the membrane and more negative inside.

Depolarization: the action potential; the rushing in and out of positively charged ions.

Repolarization: the refractory period; the closing of the membrane and reestablishing a more negative charge inside

When can it fire again?

• Refractory Period
• The time it takes for enough of the positive ions to be pumped out.

1. Absolute Refractory period - Period immediately after an action potential when another action potential CANNOT occur. (1/1000^th of a second)

2. Relative refractory period - Period following absolute refractory period when a neuron will only respond to a stronger than normal impulse

​

​

Refractory Period

Thank your glial cells

400 ft per second (Myelinated)

vs 3 ft per second unmyelinated

2.5 Influence of Drugs on Neural Firing

Neurotransmitters

Excitatory vs Inhibitory

Reuptake

Agonist

Antagonist

Acetylcholine

Serotonin

Dopamine

Norepinephrine

Epinephrine

GABA

Glutamate

​

​

How do neurons communicate �with each other?

The sending neuron releases neurotransmitters across

a synapse to the receiving neuron.

The synapse has 4 key components.

1. Terminal button - Enlarged area at the axon terminal
2. Synaptic vesicles - Sacs in the terminal button that release chemicals called neurotransmitters into the synaptic space
3. Synaptic gap (synaptic cleft) - Tiny gap between neurons
4. Receptor sites - Location on receptor neuron where neurotransmitters can bind.

Chemical Communication

Terminal button - Enlarged area at the axon terminal

Synaptic vesicles - Sacs in the terminal button that release chemicals called neurotransmitters into the synaptic space

Synaptic gap (synaptic cleft) - Tiny gap between neurons

Receptor sites - Location on receptor neuron where neurotransmitters can bind.

Chemical Communication

Neurotransmitters

• Neurotransmitters (chemicals) released from the sending neuron that travel across the synaptic cleft and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential.

​

(b) In this pseudo-colored image from a scanning electron microscope, a terminal button (green) has been opened to reveal the synaptic vesicles (orange and blue) inside. Each vesicle contains about 10,000 neurotransmitter molecules.

What is a neurotransmitter?

chemical

messengers

that travel

across the

synapse and bind to receptor sites

on the receiving neuron

How does the process work?

When an action potential

reaches an axon’s terminal branch, it stimulates the

release of neurotransmitter

molecules.

​

These molecules

cross the synaptic gap and bind to receptor sites on the

receiving neuron.

This will either excite or inhibit a new action potential.

What is �reuptake?

a neurotransmitter’s

reabsorption by the sending

neuron

Selective Serotonin Reuptake Inhibitors

​

Citalopram (Celexa)

Escitalopram (Lexapro)

Fluoxetine (Prozac)

Paroxetine (Paxil, Pexeva)

Sertraline (Zoloft)

​

Incoming neurotransmitters can be �excitatory or inhibitory.

excitatory signal

Like the gas pedal

on the car.

​

Excitatory neurotransmitter signals trigger action.

inhibitory signal

Like the brake pedal

on the car.

​

Inhibitory neurotransmitter signals depress action.

When the excitatory impulses outnumber the inhibitory impulses, the threshold has been reached and an action potential occurs.

Neurotransmitters fit like chemical keys in chemical locks.

2 Categories of neurotransmitters:� Excitatory and Inhibitory

Excitatory

• The key fits and ‘opens’ the receiving neuron.
• Activation of the receptor causes depolarization of the membrane and promotes an action potential in the receiving neuron.

Inhibitory

• The key fits in but only stops any other keys.
• Activation of the receptor causes hyperpolarization and depresses action potential generation. ��

How do drugs alter �neurotransmission ?

​

Drugs and chemicals from outside the body alter our brain chemistry.

​

Drugs act as agonists (exciting neuron firing) or as antagonists(inhibiting neuron firing).

​

How does an agonist work?

An agonist is a drug molecule that acts to create an excitatory signal

Example: morphine mimics the actions of endorphins at μ-opioid receptors throughout the central nervous system

Drugs that excite a neuron are called Agonists

Agonist excites!!!

How does an antagonist work?

An antagonist is a drug molecule that inhibits or blocks a neurotransmitter’s action.

​

Antagonists can also work by blocking reuptake.

​

Curare is a plant poison extract. It occupies the same position on the receptor as ACh (muscle movement) but elicits no response, making it a competitive antagonist.

Drugs that inhibit a neuron are called antagonists

Antagonist stops!!!

Neurotransmitters

Serotonin

Norepinephrine

Acetylcholine (ACh)

GABA

Glutamate

Endorphins

Dopamine

​

​

Serotonin

• Functions: Mood, sleep and hunger
• Too much: Anxiety and possibly Autism
• Too little: Depression and to a lesser degree OCD and eating disorders.
• Mnemonic: Serotonin sets the emotional TONE

​

Norepinephrine

• Functions:
• alertness and arousal (vigilance).
• Active along with epinephrine (adrenaline) during SNS response.
• Too much - Anxiety and panic attacks
• Too little - Depression
• Mnemonic- EPI pen makes you alert

Acetylcholine (ACh)

• Functions: Muscle Actions and Attention
• Too much: --
• Too little: Alzheimer’s Disease: deterioration of ACh-producing neurons (Alzheimer's disease is a progressive disorder that causes brain cells to waste away (degenerate) and die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that disrupts a person's ability to function independently.)
• Mnemonic: AAA (Actions, Attention and Alzheimer's)

GABA

• Functions:
• Sleep
• Major inhibitory neurotransmitter
• Too much:
• Too little: Insomnia, Anxiety, Epilepsy (seizure disorder) and Huntington’s Disease (Huntington's disease (HD) is a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain. It deteriorates a person's physical and mental abilities usually during their prime working years and has no cure.)
• Mnemonic: ABBA puts you to sleep.

GABA Examples:

Undersupply of GABA: Insomnia

Undersupply of GABA: Seizures

• Corresponding neurons become hyperactive and susceptible to seizures

Glutamate

• Functions:
• Involved in learning and memory
• Serves as a widely distributed excitatory neurotransmitter
• Too much: Seizures and migraines (avoid MSG)
• Too little
• Mnemonic: Learn and remember not to eat MSG or you get a migraine due to all the glutamate.

Endorphins

• Functions: reduce pain
• Too much: -
• Too little: -
• Mnemonic: ENDURE Pain

Dopamine

• Functions:
• reward pathway
• voluntary movement
• Influences learning
• Too much - Schizophrenia (mental illness characterized by hallucinations and delusions)
• Too little - Parkinson's (brain disorder that leads to shaking, stiffness, and difficulty with walking, balance, and coordination)
• Mnemonic: Dopey on Dopamine

How do neurotransmitters influence behavior?

2.6 The Brain

Brainstem

Medulla

Pons

Reticular Formation

Cerebellum

Thalamus

​

Limbic System

Hypothalamus

Amygdala

Hippocampus

​

​

​

Cerebral Cortex

Frontal lobes

Parietal lobes

Occipital lobes

Temporal lobes

Motor Cortex

Somatosensory Cortex

Broca’s Area

Wernicke’s Area

Split Brain

Corpus Callosum

​

Brain Stem

Medulla

Pons

Reticular Formation

Cerebellum

Thalamus

What are the functions of the medulla?

• Breathing and beating heart (also blood pressure, barfing and blinking)
• Life support center
• Base of the brainstem

Mnemonic - Medal hanging over heart and lungs.

What are the functions of the pons?

• just above the medulla
• controls sleep �‘Puts you into REM’
• Regulates sleep wake cycle

PONS puts you into REM

What are the functions of the reticular formation?

nerve network that travels through the brainstem into the thalamus

​

helps control arousal (wakes you up) and filters incoming sensory stimuli (selective attention)

Re-TICKLE-ular Formation- tickles you awake.

What are the functions of the thalamus?

at the top of the brainstem

​

relay station for incoming and outgoing sensory information (with the exception of smell). Sends sensory signals to the correct part of the brain.

Two traffic cops named Hal and Amos routing the sensory traffic.

What are the functions of the cerebellum?

at the rear of the brainstem

​

processing sensory

input, coordinating movement

and balance, (nonverbal learning and memory)

Gymnast SaraBalance Cerebellum

Limbic System

Hypothalamus

Amygdala

Hippocampus

​

These are your rewards system.

Which structures make up �the limbic system?

What are the functions of the amygdala?

two

lima-bean-sized neural clusters

​

linked to

emotion, fear, and aggression. Starts the Fight of Flight response in the SNS.

https://thedailytexan.com/2016/07/30/experts-still-disagree-on-role-of-tower-shooters-brain-tumor/

8/1/66

What does research suggest about the functions of the amygdala?

One study showed math anxiety is associated with hyperactivity in the right

amygdala (Young et al., 2012).

Another study linked criminal behavior with amygdala dysfunction

(Boccardi et al.,2011; Ermer et al., 2012).

Researchers found when people view angry and happy faces, only the angry ones increase activity in the amygdala.

(Mende-Siedlecki et al., 2013).

What are the functions of the hypothalamus?

below (hypo) the thalamus;

​

Primary Drives: Hunger, thirst and sex�(body temperature ) The 4 Fs.

​

(helps govern the

endocrine system via the pituitary gland, linked to emotion and reward)

What does research suggest about the functions of the hypothalamus?

Stimulating the reward centers of the hypothalamus will motivate a rat to cross an electrified grid, receiving painful electric shocks, to reach a bar that will give additional stimulation.

What are the functions of the hippocampus?

Small structure with two “arms” that wrap around the thalamus

​

Helps turn your short term memories into long term memories.

What does research suggest about the functions of the hippocampus?

Humans who lose their hippocampus to surgery or injury also lose their ability to form new memories of facts and events (Clark & Maguire, 2016).

Those who survive a hippocampal brain tumor in childhood struggle to remember new information in adulthood. (Jayakar et al., 2015)

NFL players who experience one or more loss-of-consciousness concussions may later have a shrunken hippocampus and poor memory

(Strain et al., 2015).

Cerebral Cortex

Frontal lobes

Parietal lobes

Occipital lobes

Temporal lobes

Motor Cortex

Somatosensory Cortex

Broca’s Area

Wernicke’s Area

Split Brain

Corpus Callosum

What is the cerebral cortex?

The intricate fabric of

interconnected neural cells

covering the cerebral hemispheres;

the body’s ultimate control and

information-processing center.

​

It is divided into four regions called lobes.

What four lobes make up �the cerebral cortex?

frontal lobe, parietal lobe, temporal lobe and occipital lobe

• located in both right and left hemispheres

What are the functions of the �frontal and parietal lobes?

frontal lobes

Decision making and analysis.

parietal lobes

Spatial reasoning

What is spatial reasoning?

Spatial reasoning is a category of reasoning skills that refers to the capacity to think about objects in three dimensions and to draw conclusions about those objects from limited information. Someone with good spatial abilities might also be good at thinking about how an object will look when rotated, good at parallel parking, putting away leftovers in the right container, designing a floor plan etc.

What are the functions of the �temporal and occipital lobes?

temporal lobes

Hearing �(facial recognition)

occipital lobes

Processing vision

What are the functions of the �motor and somatosensory cortex?

motor cortex

somatosensory cortex

controls voluntary movements

registers information from the skin senses and body movement

What are the association areas?

Most of the brain’s cortex which integrates information involved in learning, remembering, thinking, and other higher-level functions.

​

Attention is shifted, planning occurs.

​

Not specifically devoted to motor or sensory cortex functions.

Let’s look at the research on association areas…

The prefrontal cortex in the forward part of

the frontal lobes enables judgment, planning, and processing of new memories

(de la Vega et al., 2016).

People with damaged frontal lobes may have high intelligence test scores and great cake-baking skills. Yet they would not be able to plan ahead to begin baking a cake for a birthday party

(Huey et al., 2006).

And if they did begin to bake, they might forget the recipe.

(MacPherson et al., 2016).

The case of Phineas Gage

A tamping iron accident damaged neural tracks in his frontal lobe.

His frontal lobes could no longer filter emotional reactions from the limbic system.

What are Broca’s and Wernicke’s areas?

Broca’s area

language center located in the left frontal lobe

involved in expressive language - speaking + writing

Wernicke’s area

language center located in the left temporal lobe

involved in receptive language - hearing and reading

What are Broca’s and Wernicke’s areas?

Broca’s aphasia

language center located in the left frontal lobe

involved in expressive language - speaking + writing

Wernicke’s aphasia

language center located in the left temporal lobe

involved in receptive language - hearing and reading

Corpus Callosum

Connective

superhighway

Neuroplasticity

The Brain’s ability to adapt as necessary, mostly takes place pre-synaptic pruning in adolescence.

​

​

Split Brain Patients

• Due to a seizure disorder they require an operation where their corpus callosum must be cut.
• Their Left and Right Hemispheres can no longer talk to each other.
• Sperry and Gazzaniga did experiments to see what impact this surgery has and what it tells us about the hemispheres. What they found is fascinating.

​

​

This demonstrates Lateralization.

​

Left side goes to right hemisphere

Right side goes to Left hemisphere

What will happen when the patient is asked what they saw?

What will happen when the patient is asked to find the object on the table?

What will happen when the patient is asked what they saw?

LATERALIZATION:

What will happen when the patient is asked to find the object on the table?

Split Brain Research

2.7 Tools for Examining Brain Structure and Function

Electroencephalogram (EEG)

CAT Scan

MRI (magnetic resonance imaging)

PET (positron emission tomography) scan

fMRI (functional MRI)

​

​

Case Studies: Phineas Gage

EEG (Electroencephalogram)

• Macroelectrode Techniques (old)
• Used to get a picture of overall activity in the brain
• An example is an which uses electrodes placed on a person’s scalp to measure an amplified recording of the electrical waves sweeping across the brain’s surface.

​

Sleep Research

Brain Imaging

Structural Imaging

Functional Imaging

CAT Scan

MRI

PET Scan

fMRI

CAT Scans

Computerized Axial Tomography (CAT-scan)

• Uses X-rays to create a 3-dimensional image of the brain
• CT scans can often show the size and locations of brain abnormalities caused by tumors, blood vessel defects, blood clots, strokes and other problems.

​

More CAT Scans

Not CAT Scans

MRI – Magnetic Resonance Imaging

• Magnetic Resonance Imaging (MRI)
• Uses a magnetic field and radio waves to produce computer-generated images
• They distinguish among different types of brain tissue.

​

CAT scan vs. MRI

CAT scan

MRI

• Less expensive than MRI

• Less sensitive to patient movement

• CT can be performed if you have an implanted medical device of any kind

• MRI contrast materials used for image enhancement have very low incidence of side effects

• More sensitive to patient movement

Give you the structure of the brain

PET Scans

• Positron Emission Tomography (PET)
• Use (lightly) radioactive glucose to determine location of greatest brain activity

​

PET Scan of brain exhibiting Alzheimer's Disease

PET Scan of neurotypically functioning Brain

fMRIs

Functional Magnetic Resonance Imaging (fMRI)

Shows function and structure by measuring movement of blood molecules within the brain

​

Anticipation of doing math causes pain in some people.

posterior insula -- a fold of tissue located deep inside the brain just above the ear that is associated with registering direct threats to the body as well as the experience of pain.

UChicago researchers have found that the higher a person’s anxiety about math, the more anticipating math activated areas of the brain related to experiencing pain.

How do scientists study the brain?

lesion

brain tissue is destroyed and researchers study the impact on functioning

​

stimulation

Brain regions are stimulated electrically, chemically, or magnetically and researchers study the impact on functioning

How do EEG, MEG and CT scans �image the brain?

EEG

A recording of the waves of electrical activity

across the brain’s surface measured by electrodes placed on the scalp.

MEG

A brain imaging technique that

measures magnetic fields from the

brain’s natural electrical activity.

CT

CAT

X-ray photographs taken from different angles and combined by computer to show

a slice of the brain’s structure; shows structural damage.

How do PET, MRI and fMRI scans �image the brain?

PET

A visual display of brain activity that detects where a radioactive glucose goes while the brain performs a given task. Shows activity.

MRI

A technique that uses magnetic fields and radio waves to produce computer-generated images of brain anatomy.

More detailed than CT scan.

fMRI

A measure of blood flow and brain activity by comparing successive MRI scans to show brain function or as well as structure.

Shows damage.

Which imaging techniques show structure and which indicate function?

These show the structures of the brain.

CT (CAT), MRI, and fMRI

These indicate brain functioning.

EEG, MEG, PET and fMRI

How do the various imaging �techniques compare?

AP^® Exam Tip

Knowing which brain imaging technique would be used to show activity or structure is often tested on the AP^® Exam.

Pay close attention to the chart on the previous slide and check your understanding of the various methods and results of brain imaging techniques.

2.8 The Adaptable Brain

Neuroplasticity

Neurogenesis

Psychoactive drugs

Tolerance

Addiction

Withdrawal

Physical dependence

Psychological dependence

Categories of Psychoactive Drugs: include examples of each

Depressants

Stimulants

Hallucinogens

Consciousness

​

​

​

Let’s consider London taxi drivers…

Taxi driver trainees spend 2-4 years memorizing all of the routes through London.

​

Eleanor Maguire, an Irish neuroscientist, with her peers, showed increased size in portions of the hippocampus in this population.

​

The brain changes in response to experience.

​

​

(Maguire et al., 2000, 2006)

Plasticity

• the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

​

​

How does plasticity work?

In this image, most

of the right hemisphere of a young girl’s brain has been removed

due to chronic seizures that threatened her life.

How does plasticity work? Cont.

Due to the cross-wiring of the brain, she should not have been able to move the left side of her body. Yet, her left hemisphere compensated

by putting other areas to work.

2. What Would You Answer?

The ability of our brain to adapt to damage, where one area may take over the function of the damaged area, is due to

​

• lesioning.

B. positron emission training.

C. Broca’s area.

D. Wernicke’s area.

5. Plasticity.

What is neurogenesis?

Although the brain often attempts self-repair by reorganizing existing tissue, it sometimes

attempts to mend itself through neurogenesis—producing new neurons.

Psychoactive Drugs

• chemical substances that change a person's mental state by affecting the way the brain and nervous system work.
• The changes in brain function experienced by people who use psychoactive substances affect their perceptions, moods, and/or consciousness.

Substance Use vs. Abuse

• Substance Use
• Using a substance but it does not yet interfere with a person’s life
• Substance Abuse
• Pattern of drug use that diminishes one’s ability to fulfill responsibilities
• May result in repeated use in dangerous situations
• May lead to legal difficulties related to drug use

Characteristics of Dependence

• Tolerance
• More substance is required to obtain the original effect
• Withdrawal
• After addiction, physical discomfort when the substance is stopped

​

Types of Dependence

• Psychological addiction is a psychological need to use a drug, particularly for relieving mental stress and negative emotions.
• Physical addiction is the need for a drug to alleviate physical pain. When the drug is discontinued, there are several withdrawal symptoms.

Dependence (4 of the following 7 symptoms)

• Developing a tolerance
• Experiencing withdrawal
• Using substance for a longer period or in greater quantities than intended
• Presence of a desire or repeated attempts to cut back on use

• Spending a lot of time using/obtaining the substance
• Reduction or cessation of usual activities
• Continued use despite awareness of drug’s harmful effects

Drugs

• Depressants - Slow down a part of the nervous system
• Alcohol, Barbiturates and Opiates
• Stimulants - Increase activity in a part of the nervous system
• Caffeine, Nicotine, Cocaine, and Ecstasy
• Hallucinogens - Changes the way nerve cells in your brain communicate.
• LSD, Peyote and Ketamine

Depressants

• Depressant drugs reduce neural activity and slow body functions. They include:

​

Alcohol

Barbiturates

Opiates (sometimes their own category)

Alcohol

• Second most used psychoactive drug in Western societies
• Although most often used in moderation, about 14 million Americans have problems with alcohol
• Men are three times more likely to be problem drinkers
• Around 9 percent of full-time college students ages 18 to 22 meet the criteria for past-year AUD, according to a 2019 national survey.

Alcohol

• Highly addictive
• Even moderate amounts can affect
• Perception
• Motor processes
• Memory
• Judgment
• Visual acuity
• Depth perception
• Cognitive functioning

How does alcohol work?

• It first acts as a depressant on the Frontal Lobe reducing inhibitions and slurred speech (Broca’s area)
• Then it activates on cerebellum slowing balance and coordination

Just an FYI

• Binge drinking corresponds to consuming 5 or more drinks (male), or 4 or more drinks (female), in about 2 hours. (AMA)
• CDC estimates that 16% high school students and 37% of college students meet this criteria in the past 30 days.
• The neurotoxicity causes neurons in the brain to overreact to neurotransmitters and eventually burn out causing neural loss through the reduction of gray matter and white matter for people with AUD.
• Alcohol is a contributing factor for 30% of all dementia cases and is especially harmful when a frontal lobe is still forming up to age 25

​

​

Alcohol Use Disorder - DSM 5

• Had times when you ended up drinking more, or longer, than you intended?
• More than once wanted to cut down or stop drinking, or tried to, but couldn’t?
• Spent a lot of time drinking? Or being sick or getting over other after effects?
• Wanted a drink so badly you couldn’t think of anything else?
• Found that drinking—or being sick from drinking—often interfered with taking care of your home or family? Or caused job troubles? Or school problems?
• Continued to drink even though it was causing trouble with your family or friends?
• Given up or cut back on activities that were important or interesting to you, or gave you pleasure, in order to drink?
• More than once gotten into situations while or after drinking that increased your chances of getting hurt (such as driving, swimming, using machinery, walking in a dangerous area, or having unsafe sex)?
• Continued to drink even though it was making you feel depressed or anxious or adding to another health problem? Or after having had a memory blackout?
• Had to drink much more than you once did to get the effect you want? Or found that your usual number of drinks had much less effect than before?
• Found that when the effects of alcohol were wearing off, you had withdrawal symptoms, such as trouble sleeping, shakiness, restlessness, nausea, sweating, a racing heart, or a seizure? Or sensed things that were not there?

The presence of at least 2 of these symptoms indicates Alcohol Use Disorder (AUD).

​

The severity of the AUD is defined as:

Mild: The presence of 2 to 3 symptoms

Moderate: The presence of 4 to 5 symptoms

Severe: The presence of 6 or more symptoms

Barbiturates

• “Downers”
• Often Used to treat insomnia
• Can interfere with sleep patterns and cause dependence
• Effects are similar to alcohol

Opiates

• Derived from the opium poppy
• Includes opium, morphine, and heroin
• Opiates resemble endorphins, the body’s natural painkillers
• Causes euphoria followed by clouded mental functioning

Stimulants

• Substances that excite the central nervous system

​

Caffeine

Nicotine

Cocaine

Ecstasy

Amphetamines

​

Caffeine

• Naturally occurring substance found in coffee, tea, cocoa, and chocolate
• Also added to soft drinks and pain medications
• Increases alertness
• In high doses, caffeine can cause anxiety, headaches, heart palpitations, insomnia, and diarrhea

Nicotine

• Found in tobacco
• Considered by many to be the most addictive stimulant in use today
• Affects levels of several neurotransmitters
• Depending on amount and time smoked, can have either sedative or stimulating effects
• Can lead to numerous withdrawal symptoms, including nervousness, headaches, and irritability

Amphetamines

• Amphetamines stimulate neural activity, causing accelerated body functions and associated energy and mood changes, with devastating effects.

Amphetamines

• Chemically similar to epinepherine, a hormone that activates the sympathetic nervous system
• Increase alertness as well as feelings of well-being
• Can cause euphoria followed by a crash, including severe depression
• Leads to cycle of addiction

Amphetamines

• Forms can include methamphetamine and ecstasy (MDMA)
• Ecstasy acts as both a stimulant and hallucinogen
• Even short-term use of ecstasy may have long-term consequences

Ecstasy

• Ecstasy or Methylenedioxymethamphetamine (MDMA) is a stimulant and mild hallucinogen.
• It produces a euphoric high and can damage serotonin-producing neurons, which results in a permanent deflation of mood and impairment of memory.

Cocaine

• Blocks reabsorption of dopamine
• Produces increased alertness, motivation, and euphoria
• Crash leads to anxiety, depression, and strong cravings

Hallucinogens

• Substances that distort visual and auditory perception

​

LSD

• Produces hallucinations and delusions similar to a psychotic state
• Can result in psychosis, memory loss, paranoia, panic attacks, nightmares and aggression
• Popularized by Harvard psychologist Timothy Leary

​

Marijuana

• THC, the active ingredient in marijuana, produces symptoms such as
• Mild hallucinations
• Euphoria
• Enhanced sense of well-being
• Relaxation
• Distortion of time
• Some users may experience anxiety and paranoia

2.9 Sleeping

Circadian rhythms

Sleep cycles

NREM Stages 1-3

(include wave patterns in each)

REM cycle

Sleep spindles

​

​

Sleep disorders:

Insomnia

Narcolepsy

Sleep apnea

Night terrors

​

​

​

​

Circadian Rhythm

• Our bodies’ 24-hour cycle that governs
• our sleep-wake patterns - like when you release melatonin to make yourself sleepy
• body temperature -
• hormonal cycle - like the release of cortisol
• digestive cycle - like when you excrete solid waste

How does the circadian rhythm affect �our daily functioning?

Body temperature rises as dawn nears, peaks during the day, dips in the afternoon then drops again in the evening.

Thinking and memory improve as we approach our daily peak in circadian arousal.

Age and experience may alter our circadian rhythm.

Awake

Hypnagogic

Stage 1

Stage 2

Stage 3

Stage 2

Stage 1

REM

REM = Jazz hands!

​

​

How does the SCN react during the day?

Light striking the retina signals the

suprachiasmatic nucleus (SCN)

to suppress the pineal gland’s

production of the sleep hormone

melatonin.

How does the SCN react at night?

At night, the SCN

quiets down, allowing the pineal

gland to release melatonin into the

bloodstream.

What are the two divisions of sleep stages?

NREM sleep

non-rapid eye

movement sleep; encompasses all

sleep stages except for REM sleep

REM sleep

rapid eye movement

sleep; a recurring sleep stage during which vivid dreams

commonly occur

What does the suprachiasmatic nucleus (SCN) do for Circadian Rythms?

• a pair of cell clusters in the hypothalamus that controls circadian rhythm
• In response to light, the SCN causes the brain’s pineal gland to decrease its production of the sleep-inducing hormone melatonin in the morning and to increase it in the evening thus modifying our feelings of sleepiness.
• This is why blue light is so important because the SCN thinks blue light is the same as the blue light you see from the sun during th day.

.

1. What Would You Answer?

Which of the following represents a circadian rhythm?

​

1. A burst of growth occurs during puberty.
2. The sleep cycle is roughly 90 minutes long.
3. Our bodies sleep and wake on a roughly 24-hour schedule.
4. Our bodies become paralyzed when we enter REM sleep.
5. Pulse rate increases when we exercise.

What is sleep?

a periodic, natural loss

of consciousness — as distinct

from unconsciousness resulting

from a coma, general anesthesia,

or hibernation

​

(Adapted from Dement, 1999.)

How do psychologists research biological rhythms that occur during sleep?

EEG records brain wave activity while sleeping.

Varying wave patterns occur during sleep.

Sleep Stages

About every 90 minutes, we pass through a cycle of five distinct sleep stages stages.

Awake & Alert

During strong mental engagement, the brain exhibits low amplitude and fast, irregular beta waves (15-30 cps). An awake person involved in a conversation shows beta activity.

Beta Waves – It’s BETA to be awake!

What are alpha waves?

When you are in bed with your eyes closed, the researcher in the next room sees on the

EEG the relatively slow alpha waves of your awake but relaxed state. Then you slowly enter sleep.

Twilight - Awake but Relaxed

When an individual closes his eyes but remains awake, his brain activity slows down to a large amplitude and slow, regular alpha waves (9-14 cps). A meditating person exhibits an alpha brain activity.

Moving into sleep.

We seem unaware of the moment we fall into sleep, but someone watching our brain waves could tell.

(Dement, 1999)

What is Stage 1?

During this brief NREM-1 sleep you may experience fantastic images resembling hallucinations. THETA WAVES

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You may have a sensation of falling or floating weightlessly. Sometimes a leg or arm may jerk.

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These hypnagogic sensations may later be incorporated into your

memories.

What is Stage 2?

You then relax more deeply and begin about 20 minutes of NREM-2 sleep, with its periodic

sleep spindles — bursts of rapid, rhythmic brain-wave activity, due to thalamic activity and K-complexes - memory consolidation

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Although you could still

be awakened without too much difficulty, you are now clearly asleep.

What is Stage 3?

During this slow-wave sleep, which

lasts for about 30 minutes, your brain emits large, slow delta waves and you are hard to

awaken.

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Have you ever said, “That thunder was so loud last night!” only to have a friend respond, “What thunder?” Those who missed the storm may have been in delta sleep.

Sleep Stages 3-4 used to be seen as distinct….but science!!!

During deepest sleep (stages 3), brain activity slows down. There are large-amplitude, slow delta waves (1.5-4 cps).

Awake

Twilight

Stage 1

Stage 2

Stage 3

Stage 2

Stage 1

REM

90-Min

Cycles

With each 90-minute cycle, stage 3 sleep decreases and the duration of REM sleep increases.

AP^® Exam Tip

Study this cycle of sleep carefully.

One common mistake that students make is to believe that REM sleep comes directly after Stage 4.

As you can see, it does not. You have to cycle back up to REM

What is REM sleep?

rapid eye movement

sleep; a recurring sleep stage during which vivid dreams commonly occur

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REM is known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.

What physiological events occur during REM?

Heart rate rises; breathing becomes

rapid and irregular.

Genitals become aroused, men may have an erection, women may experience vaginal lubrication.

Muscle paralysis occurs, except for an

occasional twitch.

2. What Would You Answer?

Shortly after falling asleep, James experiences the hypnagogic sensations of falling. It is most likely that he is in which stage of sleep?

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1. sleep spindles

B. NREM-1

C. NREM-2

D. NREM-3

5. REM

How does sleep change as we age?

As people age, sleep becomes

more fragile, with awakenings

common among older adults.

How do biology and environment interact in our sleep patterns?

Sleep patterns are genetically influenced, but they are also culturally influenced.

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In Britain, Canada, Germany, Japan, and the United States, adults average 7 hours of sleep a night on work days, 7-8 hours on other days.

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(NSF, 2013)

Why do American students get less sleep than their Australian counterparts?

earlier school start times

increased extracurricular activities

lack of parent-set (and enforced) bedtimes

What three environmental factors play a role in our biological ability to sleep?

modern electric lighting

shift work

social-media diversions

What are sleep’s functions?

protection

At the end of the day’s hunting, gathering, and travel, our ancestors were better off asleep in a cave, out of harm’s way.

Those who didn’t wander around dark cliffs were more likely to leave descendants; natural selection!

recuperation

Sleep helps restore the immune system and repair brain tissue.

Sleep gives resting neurons time to repair themselves, while pruning or weakening

unused connections

What are more of sleep’s functions?

Solidifies memories

Sleep consolidates our memories by replaying recent learning

and strengthening neural connections.

feeds creative thinking

Dreams can inspire noteworthy artistic and scientific achievements.

A complete night’s sleep gives a boost to

our thinking and learning.

What are sleep’s other functions?

supports growth

During slow-wave sleep, which occurs mostly in the first half of a night’s sleep, the pituitary gland releases human growth hormone, which is necessary for muscle development.

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3. What Would You Answer?

Which of the following sleep theories would best explain why athletes perform better after a full night’s sleep?

1. memory

B. protection

C. growth

D. recuperation

5. creativity

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REM Rebound

• When you are sleep deprived you lose out on two types of sleep, REM and NREM (non-REM). Typically when you have a chance to fall asleep after sleep deprivation you have a tendency to get more REM sleep than you would normally get.
• This is your body's way of trying to catch up on its REM sleep.

Sleep Disorders

• Insomnia
• Difficulty falling asleep (+25 mins) or remaining asleep
• Affects about 35 million Americans
• May be related to stress, depression, medication
• Can also be caused by noise, temperature, or trying to sleep in a new environment

Sleep Disorders

• Sleeptalking and sleepwalking
• Usually occurs during Stage 4 sleep
• More common in children
• Sleepwalking more common in boys
• Night terrors
• Episodes of fright that occur during stages 3 or 4 of NREM sleep
• Person may sit up or scream, but likely will not recall the episode in the morning

Sleep Disorders

• Apnea
• Person stops breathing momentarily during sleep
• Obstructive vs central
• Affects about 10 to 12 million Americans
• REM Behavior Disorder
• Body fails to paralyze during REM sleep.
• Sleepwalk with me
• Sleep Paralysis
• Body fails to undo the paralysis briefly upon walking.

Sleep Disorders

• Narcolepsy
• Suddenly falling asleep without warning during waking hours
• Narcoleptics often experience loss of muscle tone as well
• May also drop into REM sleep immediately, causing hallucinations
• Likely caused by a central nervous system defect

2.9 Dreaming

Dreams

Wish Fulfillment

Manifest Content

Latent Content

Activation Synthesis

Information Processing

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Dream Findings

1. Negative Emotional Content: 8 out of 10 dreams have negative emotional content.
2. Failure Dreams: People commonly dream about failure, being attacked, pursued, rejected, or struck with misfortune.
3. Sexual Dreams: Contrary to our thinking, sexual dreams are sparse. Sexual dreams in men are 1 in 10; and in women 1 in 30.
4. Dreams of Gender: Women dream of men and women equally; men dream more about men than women.

Dream Theories

• Activation Synthesis

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• Information Processing

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• Cognitive Theory

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• Psychodynamic Theory

Dreams mean very little

Dreams mean quite a bit.

Activation-Synthesis Theory - Hobson

• Dreams result from random activation of the brain stem responsible for eye movement, muscle movement, balance, and vision.
• The brain then synthesizes (combines) this activity with existing knowledge and memories as if the signals came from the environment.
• How we interpret the random images and sensations is the dream’s meaning.

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Information Processing – Cartwright

• Dreams help us sort the days events and consolidate our memories
• Dreams may help sift, sort, understand, and fix a day’s experiences in our memories.
• They may also help us work out unsolved problems. We go to bed with a problem, and when we wake up the problem is solved (or forgotten, which may be a solution in itself).
• When we are under stress or depressed, we sleep longer, and the amount of time spent in REM increases. This fact strongly suggests that we are working on the things that are worrying us while we dream.

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Cognitive Theory – G. Stanley Hall

• Dreams reflect emotional preoccupations of waking life—relationships, sex, work, health.
• Images in a dream are sometimes symbols for things in everyday life.
• This theory agrees with Freud that dreams contain symbols, but there is no “latent” (unconscious) meaning. The meaning is at the surface level—”manifest” content.

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Psychodynamic Theory - Freud

• Wish-fulfillment
• Your personality is made up of three parts (Id, Ego and Super Ego)
• Dreams provide a psychic safety valve to discharge unacceptable feelings from the Id.
• Libido (sex drive) and Thanatos (aggression)
• The manifest content is the actual literal subject matter of the dream
• The latent content is the underlying meaning of these symbols.

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Dream Theories