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What is Biopsychology? Chapter 1

The origins of biopsychology Nature and nurture. What is Biopsychology? Chapter 1. The Origins of Biopsychology. What is neuroscience ? The study of the nervous system and behavior What is biopsychology ? The study of the body/behavior relationships by psychologists

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What is Biopsychology? Chapter 1

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  1. The origins of biopsychology Nature and nurture What is Biopsychology?Chapter 1

  2. The Origins of Biopsychology • What is neuroscience? • The study of the nervous system and behavior • What is biopsychology? • The study of the body/behavior relationships by psychologists • Sometimes called psychobiology or physiological psychology • What kinds of questions do neuroscientists study? • How do we recognize the face of a friend? • What role does the brain play in depression or anxiety? • And, the hardest question of all: How does the brain’s activity result in consciousness?

  3. The Origins of Biopsychology • The mind-body or mind-brain problem • Does one control the other? • Are they one and the same? • Monism • Mind and body are composed of the same substance. • Most neuroscientists believe in materialistic (physical) monism. • Dualism • For most, the body is material but the mind is nonphysical. • Most dualists believe the mind influences behavior through the brain. ◊

  4. The Origins of Biopsychology • Descartes used a hydraulic model to explain the brain’s activity. • Animal spirits were pumped through the brain by the pineal gland, the “seat of the soul.” • The model was not supported by empiricism, which employs observation and experimentation. • Descartes’ contribution was advancing a physical explanation of behavior. ◊

  5. The Origins of Biopsychology • The Electrical Brain • Galvani (late 1700s) showed that electrical stimulation of muscle made frog’s leg move. • Fritsch & Hitzig (1870) produced movement by electrically stimulating dog’s brain. • Helmholtz measured speed of conduction in nerve. • These researchers helped establish that: • Neural conduction is biological in nature. • Neural functioning is open to scientific study. ◊

  6. The Origins of Biopsychology • Localization is the idea that specific areas of the brain carry out specific functions • Phineas Gage’s case located important behavioral controls in the frontal lobes. • Broca’s study of a brain-damaged patient with inability to speak located Broca’s area in left hemisphere • Phrenology • Gall’s extreme theory of localization • Located 35 different “faculties” of emotion and intellect • Their strength was assessed from the size of bumps on a person’s skull.

  7. PhrenologyFigure 1.6

  8. The Origins of Biopsychology • Equipotentiality • Karl Lashley proposed this extreme view. • Equipotentiality is the opposite of localization. • The brain functions as an undifferentiated whole. • The extent of damage, not the location, determines how much function is lost. • What we know today • Functions are both distributed and localized. • Behavior results from the interaction of many widespread areas of the brain. ◊

  9. The Origins of Biopsychology • The brain-mind problem is still being debated. • The Discovery Institute promotes intelligent design and a nonmaterial view. • The institute funds non-material neuroscientists. • Nonmaterialists interpret the finding that psychotherapy changes brain activity as evidence of mind changing the brain. • The materialist neuroscientists’ response: • This research can also be interpreted as the brain changing the brain. ◊

  10. Nature and Nurture • How important is nature or heredity in shaping behavior? • How important are environmental influences (nurture) in shaping behavior? • Arguments are often based on emotion, not evidence. • An increasing number of behaviors are turning out to have some degree of hereditary influence (nature). • Therefore, it is necessary to understand what nature and heredity are. ◊

  11. Nature and Nurture • The gene is the biological unit that directs cellular processes and transmits inherited characteristics. • Most located on chromosomes within the cell’s nucleus • Some are found within mitochondria • Chromosomes • Body cells have 46 chromosomes arranged in 23 pairs. • Sex cells (sperm and ova) contain 23 chromosomes. • Sex chromosomes are designated either X or Y. • XX produces female • XY produces male ◊

  12. Human ChromosomesFigure 1.8

  13. Nature and Nurture • The zygote is a fertilized egg. • Receives 23 chromosomes from the male parent’s sperm. • Receives 23 chromosomes from the female parent’s ovum. • Hence, the zygote contains 46 chromosomes. • Embryo • First 8 weeks of life • Fetus • From 8 weeks to birth ◊

  14. Nature and Nurture • Genes are made of DNA. • DNA is deoxyribonucleic acid. • DNA is a double-stranded chain of chemical molecules that looks like a twisted ladder. • DNA is often referred to as the “double helix”. • Nucleotides • Two nucleotides form each rung of the ladder. • Adenine and Thymine, and Guanine and Cytosine (A, T, G, C) • Order of these nucleotides determines genetic code. • Genes provide the directions for making proteins for use in constructing the body and to act as enzymes.

  15. DNAFigure 1.9

  16. Nature and Nurture • Because chromosomes are paired, most genes are as well. • Sometimes a single pair of genes determines a characteristic (blood type) or disease (Huntington’s disease). • Different versions of a gene are called alleles. • A dominant gene will produce its effect regardless of which gene it is paired with. • A recessive gene will have an effect when paired with the same recessive gene on the other chromosome. • X-linked traits are produced by a gene on the X chromosome that is not paired with a gene on Y.

  17. Nature and Nurture • Dominance and recessiveness are illustrated in hand clasping preference. • The allele for left thumb over right thumb preference is dominant, whereas the allele for right-over-left is recessive. • If Sue is homozygousfor the dominant allele she will show left preference. • If Bill is heterozygousfor hand clasping, he will also show left preference. • Sue and Bill have the samephenotype, but differentgenotypes. • What combination of alleles would be required for someone to show right preference?

  18. Hand ClaspingFigure 1.10

  19. Nature and Nurture • Example 1: In the previous slide, both Sue and Bill show left-over-right preference, but Sue is homozygous and Bill is heterozygous for the trait. • What preference will their children show? • All will likely show left-over-right preference. • Why? • Example 2: Kelly and Jason are both heterozygous for the trait of hand clasping preference. • What preference will their children show? • Three out of four (75%) are likely to show left-over-right preference. • Why will one out of four (25%) show right-over-left preference?

  20. Nature and Nurture • Some traits are determined by a single pair of genes. • This is rare. • Most characteristics are determined by several genes and hence are referred to as polygenic traits. • Examples of polygenic characteristics: • Height • Intelligence • Psychological disorders • Genes do not provide a script for behavior. • Genes control the production of proteins. ◊

  21. Nature and Nurture • Human Genome Project • Goal was to map the location of all the genes of the human chromosomes and to determine their codes. • This was an international effort. • In 2000—after just 10 years—“rough drafts” of the human genome were available. • Three years later the project was 99% complete. • What has the map revealed? • We have only 20,000 to 25,000 functioning genes. • About 97% of our DNA does not encode for proteins and is referred to as “junk” DNA, but it must play some role. • Noncoding DNA most likely controls gene expression.

  22. Nature and Nurture • How many different genetic combinations can be passed on from two parents to their offspring? • 60-70 trillion! • Hence, sexual reproduction increases individuality as well as adaptability. • This variability is an essential component of Darwin’s principle of natural selection. • Individuals whose genes provide them with a greater ability to adapt are more likely to survive and transmit their genes to more offspring. ◊

  23. Nature and Nurture • Heritability is the percentage of the variation in a characteristic that can be attributed to genetic factors. • Heritability can be calculated by comparing concordance rate for types of twins • Identical twins share 100% of their genes. • Fraternaltwins share about 50% of their genes. • Some estimated heritability rates are • Intelligence: 50% • Schizophrenia: 60-90% • Height: 90% ◊

  24. Twin Studies: Behavioral vs. Medical DisordersFigure 1.13

  25. Nature and Nurture • About half of the variability in behavioral characteristics is due to heredity; the other half is due to environmental influences. • The vulnerability model points out that the influence of genes is only partial. • Genes contribute a predisposition for the disorder. • The combination of genes and environmental factors determines whether the individual develops the disorder. • Most scientists reject the nature-versus-nurture concept; they conclude that heredity and environment interact to influence behavior. ◊

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