Chapter 2

Biology and Psychology

LECTURE OUTLINE

I. The Nervous System: On Being Wired.

A. Phineas Gage story: The brain’s influence on personality; the nervous system serves as the base for behaviors, emotions, and cognitions.

B. Neurons: Into the Fabulous Forest.

1. Neurons: the nerve cells of the body; the metaphoric tree.

a. Cell Body: contains the nucleus which generates energy

b. Dendrites: receive incoming messages from adjourning cells (roots).

c. Axon: carry messages away from the cell body (trunk).

d. Terminals (terminal buttons): bulb shaped structure at the end of the axon.

e. Myelin: fatty substance around axons that facilitate conduction.

f. Glial cells: remove dead neurons and waste products from the nervous system.

g. Afferent neurons: sensory input.

h. Efferent neurons: motor output.

i. SAME: Sensory = Afferent, and Motor = Efferent.

C. The Neural Impulse: Let Us “Sing the Body Electric”.

1. Neural Impulse: message traveling along the neuron; between 2 and 225 miles an hour.

2. An Electrochemical Voyage.

a. Neuron resting potential: -70 millivolts (negative charge).

b. Depolarized: action of the cell while it becomes positively charged.

c. Action potential: positively charged neuron returning to the resting state of being negatively charged. The “message” is sent.

3. Firing: How Messages Voyage from Neuron to Neuron.

a. Neuron Firing: neurons attempt to transmit messages to other neurons, muscles or glands.

b. Threshold: Each neuron has a threshold; the cell will not fire until the threshold is reached.

c. All or None Principle: When the threshold is reached the neuron fires an impulse of the same strength.

d. Refractory Period: a period of time when the neuron will not fire; period of recovery during which positive sodium is not allowed to pass through the neural membrane.

4. The Synapse: On Being Well Connected.

5. Synapse: junction (fluid filled gap) between neurons.

D. Neurotransmitters: The Chemical Keys to Communication.

1. Synaptic Vesicles: sacs in the axon terminals, which contain neurotransmitters.

2. Neurotransmitters: the chemical keys to communication; spilled into the synaptic cleft (synapse) and influence the receiving neuron

3. Receptor Site: specifically tailored site on the receiving neuron where the chemical key (neurotransmitter) fits.

4. Reuptake: reabsorption of neurotransmitters by the sending neuron.

5. Excitatory: neurotransmitter influence on the receiving cell causing it to fire.

6. Inhibitory: neurotransmitter influence on the receiving cell preventing it from firing.

7. Some Key Chemical Keys.

a. Acetylcholine (ACh): controls muscle contractions; can be both excitatory and inhibitory.

i. Example of Curare and Botulism both leading to paralysis

ii. Hippocampus: ACh is also found in the hippocampus and facilitates memory; decreases with Alzheimer’s disease leading to memory problems.

b. Dopamine: affects voluntary movements, learning, memory and arousal.

i. Deficiencies are linked to Parkinson’s Disease in which people progressively lose control over their muscles; Muhammad Ali and Michael J. Fox.

ii. Schizophrenia: people with schizophrenia may have more receptor sites for dopamine leading to confusion and false perceptions.

c. Norepinephrine: produced largely in the brain stem; acts as a neurotransmitter and as a hormone; involved in general arousal, learning and memory, and eating; linked to mood disorders.

i. Example of cocaine, which creates an excess of norepinephrine leading to persistent arousal.

d. Serotonin: involved in emotional arousal and sleep. Deficiencies have been linked to eating disorders, alcoholism, depression, aggression, and insomnia.

i. Example: LSD which inhibits this inhibitory neurotransmitter leading to increased brain activity including hallucinations

e. Gamma-aminobutyric acid (GABA): inhibitory neurotransmitter that may help calm anxiety reactions. Tranquilizers and alcohol may quell anxiety by binding with GABA receptors.

f. Endorphins: inhibitory neurotransmitter; endogenous morphine. Natural painkiller.

i. Experienced by runners as the runner’s high.

g. Billions and billions of vesicles pouring neurotransmitters into synaptic clefts at any given time; several hundred times every second.

E. The Parts of the Nervous System.

1. Nerve: a bundle of axons.

2. Central Nervous System: brain and spinal cord.

3. Peripheral Nervous System: afferent and efferent neurons, which transmit messages from the brain or spinal cord to muscles and glands.

4. The Peripheral Nervous System: The Body’s Peripheral Devices.

a. Somatic Nervous System: afferent and efferent neurons that transmit sights, sounds, smells, temperature, body positions, etc.

i. Purposeful body movements.

b. Autonomic Nervous System: “Automatic” regulates the glands and internal organ muscles; heartbeat, respiration, digestion, dilation of the pupils, etc.

i. Sympathetic Division: active during processes that involve spending body energy; fight or flight.

ii. Parasympathetic Division: active during processes that replenish reserves of energy.

5. The Central Nervous System: The Body’s Central Processing Unit.

a. Spinal Cord: column of nerves transmits messages from sensory

receptors to the brain and from the brain to muscles and glands throughout the body

i. Spinal Reflexes: unlearned response to a stimulus that may involve only two neurons: afferent and efferent.

ii. Interneuron: a third neuron that transmits the neural impulse from the sensory neuron through the spinal cord to the motor neuron.

iii. Gray Matter: non-myelinated neurons; found in brain and spinal cord.

iv. White Matter: myelinated neurons; found in brain and spinal cord.

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II. The Brain: Wider Than the Sky

A. Gender differences: Men brains are 15% larger than women’s brains; Women’s brains run hotter (metabolize more glucose).

B. Seeing the Brain Through the Eyes of the Psychologist.

1. Paul Broca: hobby of craniometry or measurement of the skull.

a. Patient named Leborgne who could understand language but could utter only meaningless sounds. After his death Broca performed an autopsy and found a part of his brain had deteriorated.

b. Broca tied this into speech, now called Broca’s area.

2. Accidents.

a. Accidents provide unplanned, uncontrolled opportunities of studying the brain (see Phineas Gage).

3. Experimenting with the Brain.

a. Lesioning: damaging part of the brain.

4. The Electroencephalograph (EEG).

a. EEG detects minute amounts of electrical activity in the brain.

5. Brain Imaging Techniques.

a. CAT (computerized axial tomograph): a scan which passes a narrow X-ray beam through the head and measures brain structures, generating a three dimensional image of the brain.

i. Reveals deformities in shape and structure that are connected with blood clots, tumors, and other health problems.

b. PET (positron emission tomography): computer-generated image of the activity of parts of the brain by tracing the amount of glucose used. A harmless amount of radioactive compound (tracer) is mixed with glucose and injected into the blood stream.

i. Used to see which parts of the brain are most active when we are engaged in various activities (listening to music, working out math problems, etc.)

c. MRI (magnetic reasoning imaging): the person lies in a powerful magnetic field and is exposed to radio waves that cause parts of the brain to emit signals; relies on subtle shifts in blood flow.

i. MRI has shown people with schizophrenia have smaller prefrontal regions but larger ventricles.

ii. fMRI Functional MRI enables researchers to observe the brain while it is working.

C. A Voyage Through the Brain.

1. Hindbrain: where the spinal cord meets the brain. Contains three structures, the medulla, pons, and cerebellum.

a. Medulla: regulates vital functions such as heart rate, blood pressure, and respiration.

b. Pons: transmits information about body movements and is involved in functions related to attention, sleep/alertness and respiration.

c. Cerebellum: involved in maintaining balance and controlling motor behavior.

2. Reticular Activating System (RAS): vital in the functions of attention, sleep and arousal.

3. Forebrain: forward most part of the brain containing the thalamus, hypothalamus, limbic system and the cerebrum.

a. Thalamus: relay station for sensory stimulation.

b. Hypothalamus: vital for the regulation of body temperature, concentration of fluids, storage of nutrients, and various aspects of motivation and emotion.

i. Also involved in hunger, thirst and sexual behavior. (Pleasure center of the brain see the rat experiment).

c. Limbic System: made up of several structures including the amygdala, hippocampus, and parts of the hypothalamus.

i. Involved in memory, emotion and in the drives of hunger, sex and aggression.

ii. Amygdala: connected with aggression, fear response, and vigilance.

d. Cerebrum: responsible for thinking and language.

4. Corpus Callosum: a bundle of some 200 million nerve fibers connecting the two hemispheres.

D. The Cerebral Cortex: The “Bark” That Reasons.

1. Cerebral Cortex: outer layer of the cerebrum; about 1/8 of an inch thick.

2. Involved in almost every bodily activity, including most sensations, and most responses.

3. Frontal Lobe: in front of the central fissure, contains the motor cortex, which causes our body to move.

4. Parietal Lobe: behind central fissure, contains the somatosensory cortex, which receives messages from skin senses all over the body.

5. Temporal Lobe: lies below the lateral fissure, contains the auditory area (hearing).

6. Occipital Lobe: lies behind the temporal lobe and is involved with vision.

7. Association Areas: areas of the cerebral cortex that are not primarily involved in sensation or motor activity.

a. Make possible the breadth and depth of human learning, thought, memory and language.

8. Language Functions.

a. Aphasia: disruption in the ability to understand or produce language.

b. Wernicke’s Area: in the temporal lobe responds mainly to auditory information.

c. Broca’s area: processes information and sends it to the motor cortex.

d. Wernicke’s aphasia: impaired ability to comprehend speech and to think of the proper words to express.

e. Broca’s aphasia: Damage to this area results; people can understand language but will speak slowly in simple sentences.

E. Left Brain, Right Brain.

1. Left-brain: primarily logical and intellectual.

2. Right brain: primarily intuitive, creative, and emotional.

a. At best this is exaggerated. The hemispheres do not act independently as they are connected by the corpus callosum.

F. Handedness: Is Being Right-Handed Right?

1. Lefties: 8-10% of people are left handed; more common in males.

a. Has been connected with language problems, dyslexia, stuttering, migraine headaches, allergies, and schizophrenia.

b. On the other side being left handed is associated with artists, musicians, and mathematicians.

2. Handedness runs in families.

G. Split Brain Experiments: How Many Brains Do You Have?

1. Split brain: some people with epilepsy have split brain operations in which much of their corpus callosum is severed.

a. Characteristics of split brain: each hemisphere has a mind of it’s own.

i. One patient described a situation he encountered, as one hemisphere liking reading and other not. If he shifted the book from his right hand to his left, his left hand would put the book down.

III.The Endocrine System: Chemicals in the Blood.

A. Glands: secrete hormones. Two types:

1. With ducts (saliva, sweat, tears).

2. Without ducts (released into the blood stream).

B. The Pituitary and the Hypothalamus: Master and Commander

1. The hypothalamus secretes hormones that influence the pituitary.

C. Pituitary Gland: implicated in growth, sometimes referred to as the Master Gland as it influences other glands in the endocrine system.

1. Growth Hormone: regulates growth of muscles, bones and glands.

2. Prolactin: regulates maternal behavior in lower animals such as rats, also produces milk in women.

3. Antidiuretic Hormone (ADH): inhibits production of urine when fluid levels in the body are low.

4. Oxytocin: stimulates labor in pregnant women.

D. The Pineal Gland: secretes melatonin.

1. Melatonin: secreted by the Pineal gland and helps regulate the sleep-wake cycle.

E. The Thyroid Gland: The Body’s Accelerator.

1. Thyroxin: secreted by the thyroid and affects the body’s metabolism.

a. Hypothyroidism is too little thyroxin and results in being overweight.

b. Hyperthyroidism is too much thyroxin and is characterized by excitability, insomnia, and weight loss.

c. Cretinism is a conditioned caused by a deficiency in thyroxin in children, which leads to stunted growth and mental retardation.

2. The Adrenal Glands: Coping With Stress.

a. Adrenal glands: release hormones to increase resistance to stress called corticosteroids.

b. Promote muscle development and the release of sugar in the liver making more energy available.

c. Epinephrine: is also known as adrenaline; produced by the adrenal glands.

3. Life Connections: Steroids, Behavior, and Mental Processes

a. Increase muscle mass, heighten resistance to stress, increase body’s energy

b. Use to enhance athletic performance

c. Ethics: athletes should play fair

i. Linked to liver damage and other health problems

4. The Testes and the Ovaries.

a. Testosterone: produced by the testes and in small amounts by the ovaries.

b. Considered to be the male sex hormone as it aids in the development of male sex organs.

c. During puberty the release of testosterone promotes the development of primary and secondary sex characteristics.

i. Primary sex characteristics: those characteristics involved in reproduction: increased penis size, sperm producing ability of the testes.

ii. Secondary sex characteristics: Not directly related to reproduction: presence of a beard, deeper voice.

d. Estrogen and Progesterone: produced by the ovaries and in small amounts by the testes.

i. Fosters female reproductive capacity and secondary sex characteristics. The levels of estrogen and progesterone vary and regulate the woman’s menstrual cycle.

5. Coping with Premenstrual Syndrome (PMS)

a. Premenstrual Syndrome (PMS): three out of four women report having some psychological and physical problems such as depression, anxiety, and headaches during the four to six days that precede menstruation.

b. However only one in ten has symptoms severe enough to impair academic, occupational, or social functioning.

c. PMS may be a complex interaction between ovarian hormones and neurotransmitters. Once seen as something a woman must tolerate, today there are many treatment options (diet, exercise, hormone treatments).

d. How to Handle Menstrual Discomfort.

i. Don’t blame yourself.

ii. Keep track of your menstrual symptoms to help you and your doctor identify patterns.

iii. Develop strategies for dealing with days on which you experience the most distress.

iv. Ask yourself whether you harbor self-defeating attitudes that might be compounding distress.

v. See a doctor about your symptoms.

vi. Develop nutritious eating habits.

vii. If you feel bloated, eat smaller meals.

viii.Vigorous exercise.

ix. Check with your doctor about herbal, vitamin and mineral supplements.

x. Ibuprofen and other medications available over the counter may be helpful for cramping.

e. Menstruation is triggered by a sharp drop off in sex hormones. Some gynecologists prescribe estrogen replacement though this is not hazard free.

f. Remind yourself that menstrual problems are time limited.

6. Menopause: When the Decline in Sex Hormones Becomes Permanent.

a. Menopause: when the drop off in female sex hormones becomes permanent.

i. Characterized by the cessation of menstruation. Climacteric caused by the falling off in the secretion of estrogen and progesterone. Loss of reproductive ability.

Ø Other characteristics: hot flashes, perspiration, loss of sleep, feelings of anxiety and depression.

Ø The majority of women get through the menopause transition with little or no problems.

Ø Some women do experience physical and emotional problems.

b. Hormone Replacement Therapy (HRT).

i. HRT: consists of synthetic estrogen and progesterone used to offset the effects of declining of naturally occurring hormones.

Ø Positives: May help reduce hot flashes, lower the risk of osteoporosis, colon cancer, and age related cognitive declines. Possibly raises the levels of “good” cholesterol and lowers the levels of “bad” cholesterol.

Ø Negatives: Increases in some kinds of cancers including breast and endometrial cancer. No cardiac benefits, possible increased risk of stroke and heart attacks.

c. Andropause (Viropause or Manopause).

i. Andropause: suggests a fall off of levels of the male sex hormone androgens.

Ø The decline is typically more gradual in men than in women.

Ø Characteristics include loss of fertility, problems in achieving and maintaining an erection, loss of bone mass loss of muscle, loss of height, body fat percent nearly doubles and loss of some hearing and vision.

Ø To help alleviate the symptoms try:

§ Exercise.

§ Diet rich in calcium and vitamin D.

§ Hormone replacement therapy.

ii. Irritable Male Syndrome.

Ø Characteristics: the drop off of testosterone may lead to anxiety, depression, or irritability in men.

iii. Hormone Replacement Therapy (HRT) in Men.

Ø Each year 1 million prescriptions are written for testosterone.

§ Positives: May boost strength, energy, and the sex drive.

§ Negatives: connected with risk of prostrate cancer and cardiovascular disease.

IV. Evolution and Heredity: The Nature of Nature.

A. Theory of Evolution.

1. Published “The Descent of Man” in 1871.

2. Natural Selection: Survival of the fittest.

3. Biology serves as the material base for our behaviors, emotions and cognitions.

B. Evolutionary Psychology: “Doing What Comes Naturally”.

1. Mutations: differences in individual traits and/or adaptations for survival?

2. Evolutionary Psychology: Applying adaptation and natural selection to mental processes and behavior.

3. Instincts: stereotyped pattern of behavior that is triggered in specific situations

a. Examples of instincts: The Egg Zone; Stickleback Fish; Song of the Sparrow.

C. Heredity, Genetics, and Behavioral Genetics

1. Heredity: one’s biological structures and processes transmitted from generation to generation.

2. Genetics and Behavioral Genetics.

a. Behavioral Genetics: Bridges the sciences of psychology and biology. Concerned with the genetic transmission of traits that give rise to patterns of behaviors.

b. Molecular Genetics: attempts to identify specific genes that are connected with behavior and mental processes.

i. Examples of this include: sociability, shyness, aggressiveness, thrill seeking, anxiety, depression, schizophrenia, bipolar disorder, alcoholism, and criminal behavior.

3. Genes and Chromosomes: The Building Blocks of Heredity”.

a. Genes: basic building blocks of heredity. 30,000 - 40,000 genes within every cell of a person’s body.

b. Chromosomes: strings of genes. Each cell contains 46 arranged in 23 pairs.

c. DNA: Chromosomes are large complex molecules of deoxyribonucleic acid (DNA).

i. Human Genome Project: has learned that the sequencing of your DNA consists of about 3 billion DNA sequences.

ii. Genetic Code: The DNA sequences that “define” each person (genotype).

Ø Sperm and Egg: 23 chromosomes from the father’s sperm and 23 chromosomes from the mother’s egg. When the egg is fertilized by the sperm they form 23 pairs.

Ø Sex Chromosomes: The 23^rd pair of chromosomes, which determine a person’s sex, male or female. X female; Y male.

Ø Determined by father.

d. Down Syndrome.

i. Down Syndrome: an extra chromosome on the 21^st pair. Usually contributed by mother.

ii. Characteristics: downward sloping fold of skin at the inner corner of the eyes, a round face, a protruding tongue, broad flat nose, mental retardation, and physical problems that can result in death by middle age.

4. Kinship Studies: Is the Behavior of Relatives Related?

a. Parents and Children: 50% of their genes in common. Aunts and Uncles have a 25% overlap with nieces and nephews. 12.5% overlap with cousins.

b. Kinship Studies: Studies which attempt to compare the presence of traits and behavior patterns in people who are biologically related or unrelated to help determine the role of genetic factors.

c. Twin Studies: Looking Into the Genetic Mirror.

i. Monozygotic Twins (MZ): Identical twins from the same fertilized egg.

ii. Dizygotic Twins (DZ): Fraternal twins, two separate fertilized eggs.

iii. Twin studies compare the presence of traits in MZ twins, DZ twins and others to help determine the role of genetic factors.

Ø If MZ twins show greater similarity on a trait than DZ twins a genetic basis for the trait has been suggested.

Ø The case of the Jims.... MZ twins raised apart, both named Jim, both were married and divorced, both trained to be policemen, first sons named James Allen, drove same kind of car, vacationed at the same beach, enjoyed carpentry as a hobby.

d. Adoption Studies.

i. Adoption studies: look for similarities between children and their natural and adoptive parents.

Ø When children reared by adoptive parents are more similar to their natural parents in a particular trait, strong evidence exists for a genetic role.

5. Selective Breeding: The Nurture of Nature.

a. Selective breeding: selective breeding to enhance desired physical and behavioral traits.

i. Examples: cattle, chicken, dogs.

b. Tryon rat studies: Bred rats to become “maze dull” and “maze bright”.

Ø By the seventh generation maze bright rats are making only one error per trial, maze dull are making 9-10 errors per trial.

V. A Closer Look: Of Spiderman, Dr. Octopus, and Brain-Machine Interfaces

A. Brain-Machine Interface (BMI)

1. Straddles the world of fact and fiction.

2. Current approach is based on the idea that a human user could enact voluntary motor intentions through a direct interface between his brain and an artificial effector.

3. Humans can control computer cursors and nonhuman primates control the movement of cursors and robots to perform different kinds of reaching and grasping tasks.

VI. A Closer Look: Of Mice and Men: On Hormones, Attachment, and Fatherhood.

A. Increasing vasopressin levels in mice turned indifferent males into caring monogamous and protective mates and fathers.

B. Vasopressin is normally secreted by the pituitary gland and in involved in reproduction and nurturing of young.

C. Vasopressin seems to have an impact on voles but has not yet been shown to be connected with the formation of bonds between men and women, and men and children.

VII. A Closer Look: Are You a Human or a Mouse (or a Chimp or a Carrot)?: Some Fascinating Facts About Genes.

A. Human genetic code overlaps about 25% with that of a carrot.

B. The genetic codes of other life forms have the similar four chemical makeups as humans.

1. This is what makes mice excellent stand-ins for humans in medical research.

C. Chimpanzees are humans’ closest relatives.

1. Only 1.58% of the genetic code of the chimp differs from our own.

D. Recent DNA analysis suggests that humans may have interbred with other humanoids rather than simply replacing them.

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