Chapter 1 The Major Issues

1. Chapter 1The Major Issues

2. The Mind-Brain Relationship • Biological Psychology is the study of the physiological and genetic basis of behavior. • Emphasis is placed upon physiological, evolutionary and developmental mechanisms of behavior. • A strong emphasis is placed upon brain functioning.

3. Fig. 1-1, p. 2

4. The Mind-Brain Relationship • Brain functioning can be explained at a more microscopic level in terms of neuron and glia activity.

5. Fig. 1-2, p. 3

6. The Mind-Brain Relationship • Biological explanations of behavior fall into four categories: • Physiological- emphasis on brain and other vital organs. • Ontogenetic- describes the development of a structure or behavior. • Evolutionary- focuses upon the evolutionary history of a behavior. • Functional- describes why a structure or behavior evolved as it did.

7. The Mind-Brain Relationship • Deep understanding of a particular behavior is tied to being able to explain the behavior from each of these perspectives.

8. The Genetics of Behavior • Both genes and environment interact to shape human behavior. • The fundamental issue is how much a role genetics do play in shaping human behaviors. • Examples: psychological disorders, weight gain, personality, sexual orientation?

9. The Genetics of Behavior • Genes are basic units of heredity that maintain their structural identity from one generation to another. • Genes are aligned along chromosomes (strands of genes) and come in pairs.

10. The Genetics of Behavior • A gene is a portion of a chromosome and is composed of deoxyribonucleic acid (DNA). • DNA serves as a model for the synthesis of ribonucleic acid (RNA).

11. Fig. 1-7, p. 12

12. The Genetics of Behavior • RNA is a single strand chemical that can serve as a model for the synthesis of proteins. • Proteins determine the development of the body by: • forming part of the structure of the body. • serving as enzymes that serve as biological catalysts and regulate chemical reaction in the body.

13. The Genetics of Behavior • Homozygous for a gene means that a person has an identical pair of genes on the two chromosomes. • Heterozygous for a gene means that a person has an unmatched pair of genes on the two chromosomes.

14. The Genetics of Behavior • Some genes can be either dominant or recessive. • Examples: eye color, breast cancer genes, ability to taste PTC, curly hair • A dominant gene shows a strong effect in either the homozygous or heterozygous condition (DD, Dd, or dD). • A recessive gene shows its effect only in the homozygous condition (dd).

15. Fig. 1-8, p. 13

16. The Genetics of Behavior • Each chromosome participates in reproduction independently of the others. • Each species has a certain number of chromosomes. • Crossing over occurs when a pair of chromosomes break apart during reproduction and reconnects and attaches to the second chromosome. • BC & bc  Bc & bC

17. The Genetics of Behavior • Types of genes include: • Autosomal genes - all genes except for sex- linked genes. • Sex-linked genes -genes located on the sex chromosomes. • In mammals, the sex chromosomes are designated X & Y. • Females have two X chromosomes (XX). • Males have an X and a Y chromosome (XY).

18. The Genetics of Behavior • During reproduction: • Females contribute an X chromosome. • Males contribute either an X or a Y chromosome that determines the sex of the child. • If an X chromosome is contributed by the male, the off-spring is female. • If a Y chromosome is contributed by the male, the off-spring will be male.

19. The Genetics of Behavior • The human Y chromosome has genes for 27 proteins • The human X chromosome has genes for approximately 1500 proteins. • Thus, sex-linked genes usually refer to X-linked genes. (Example: Red-green color deficiency, Hemophilia) • Sex-limited genes are genes that are present in both sexes but mainly have an effect on one sex (Chest hair, breast size, etc.)

20. The Genetics of Behavior • Sources of variation in a species that allows for evolution to occur include: • Recombination refers to a new combination of genes in the off-spring that yield characteristics not found in either parent. • Mutation refers to a change in a single gene that is rare, random and often independent of the needs of the organism.

21. The Genetics of Behavior • Almost all behaviors have both a genetic component and an environmental component. • Researchers study monozygotic and fraternal twins to infer how much of a genetic component exists for a particular behavior. • Researchers also study adopted children and their resemblance to their biological parents to infer the influence of heredity.

22. The Genetics of Behavior • Heritability • Estimates of hereditary influences are often difficult to infer and are prone to error. • Sources of error include the following: • The inability to distinguish between the effects of genes and prenatal influences. • Environmental factors can inactivate genes.

23. The Genetics of Behavior • Sources of error (con’t) • Multiplier effect – genetic tendencies that guide behavior will result in a change in the environment that magnifies the original tendency. • Traits with a strong hereditary influence can by modified by environmental intervention. • e.g. PKU---phenylketonuria

24. The Genetics of Behavior • Genes do not directly produce behaviors. • Genes produce proteins that increase the probability that a behavior will develop under certain circumstances. • Genes can also have an indirect affect. • Genes can alter your environment by producing behaviors or traits that alter how people in your environment react to you.

25. The Genetics of Behavior • Evolution refers to a change in the frequency of various genes in a population over generations • Evolution attempts to answer two questions: • How did some species evolve? • How do species evolve?

26. The Genetics of Behavior • How species did evolve involves the tentative construction of “evolutionary trees”. • How species do evolve rests upon two assumptions: • Offspring generally resemble their parents for genetic reasons. • Mutations and recombination of genes introduce new heritable variations that help or harm the chance of survival and reproduction.

27. The Genetic of Behavior • Common misconceptions about evolution include the following: • Lamarckian evolution - “The use or disuse of some structure or behavior causes an increase or decrease in that behavior.” • “Humans have stopped evolving.” • “Evolution means improvement.” • “Evolution acts to benefit the individual or the species.”

28. The Genetics of Behavior • Evolutionary psychology (sociobiology) focuses upon functional explanations of how behaviors evolved. • Assumes that behaviors characteristic of a species have arisen through natural selection and provide a survival advantage. • Examples: differences in peripheral/color vision, sleep mechanisms in the brain, eating habits, temperature regulation.

29. The Genetics of Behavior • Some behaviors are more debatable regarding the influence of natural selection. • Examples include: • Life span length • Gender differences in sexual promiscuity • Altruistic behavior

30. The Use of Animals in Research • Animal research is an important source of information for biological psychology but remains a highly controversial topic. • Animal research varies on the amount of stress and/ or pain that is caused to the animal itself.

31. The Use of Animals in Research • Reasons for studying animals include: • The underlying mechanisms of behavior are similar across species and often easier to study in nonhuman species. • We are interested in animals for their own sake. • What we learn about animals sheds light on human evolution. • Some experiments cannot use humans because of legal or ethical reasons.

32. Fig. 1-12, p. 23

33. The Use of Animals in Research • Justification for research considers the amount of benefit gained compared to the amount of distress caused to the animal. • No clear dividing line exists. • Colleges and research institutions in the United States are required to have an Institutional Animal Care and Use Committee. • Oversees and determine acceptable procedures.